EPA/454-R-93-007                                    February 1993
    DETERMINATION OF VOLATILE  ORGANIC  CONTENT IN ULTRAVIOLET
                    RADIATION-CURED COATINGS,
                       METHOD DEVELOPMENT
                           FINAL REPORT
                        Lourdes  L.  Morales
                           Lori  T.  Lay
                   Emissions Measurement Branch
           Office of Air Quality Planning and standards
                Research Triangle Park,  NC    27711

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                              NOTICE


     This report has been reviewed by the Emission Measurement
Branch, Technical Support Division of the Office of Air Quality
Planning and Standards, EPA and approved for publication.
Mention of trade names or commercial products is not intended to
constitute endorsement or recommendation for use.  Copies of this
report are available through the Emission Measurement Branch
(MD-19), Research Triangle Park, North Carolina, 27711.

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                             CONTENTS

Abstract	    iv
Figures 	    v
Tables  	    v
Abbreviations and Symbols .  . . .	    vi
Acknowledgments 	   vii
   1. Introduction    	     1
   2. Conclusions   r ........ 	     3
   3. Recommendations	     4
4. Experimental Procedures   	     5
       4.1 Experimental  Apparatus 	     5
          4.1.1 Sample  Curing System   ... 	     5
          4.1.2 Drawdown  Rod	     5
          4.1.3 Other Laboratory  Equipment    	     6
       4.2 Description  of  ASTM Methods  	     6
          4.2.1 Method  A	     6
          4.2.2 Method  B	     7
       4.3 Tests  Using  ASTM Methods    	     7
       4.4 Modifications to ASTM"Methods  	     7
          4.4.1 Method  A	     7
          4.4.2 Method  B	     7
       4.5 Development  of  EPA Draft  Method  	     8
          4.5.1 Inclusion of Cure Test    	     8
          4.5.2 Elimination of  50 °C Oven  	     8
          4.5.3 Evaluation  of Coating at  Twice  Manufacturer's
          Suggested Exposure 	     8
       4.6 Evaluation  of Samples Using EPA Draft Method    .     8
   5. Results and Discussion   	     9
      5.1 Results Using ASTM Methods    	     9
          5.1.1 Results Using Method A  	     9
          5.1.2 Results Using Method B  	     9
       5.2 Modifications to ASTM Methods  	    11
          5.2.1 Method  A	    11
          5.2.2 Method  B	    11
       5.3 Development  of  EPA Draft  Method  	    23
       5.4 Summary of  EPA Draft Method	    23
       5.5 Comparison  of Methods  	    24
       5.6 Tests  of Materials with EPA Draft Method  ....    26
          5.6.1 Acrylic Coatings  	 26
          5.6.2 Epoxy Coatings	    26

          5.6.3 Polyester/Styrene Coatings  	    26
          5.6.4 Thiol/Polyene Coatings  	    26
                                11

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References
Appendices
   A.    Laboratory Data
   B.    Initial Draft  ASTM  Method   - "Proposed Test Methods for
         Determining voc of  Radiation Curable Materials"
   C.    Initial  Draft  EPA  Method  - "Determination  of Volatile
         Organic Content for Ultraviolet Radiation-Cured Coatings"
   D.    Responses to Comments on EPA Draft Method.
   E.    Revised Draft.ASTM  Method   - "Proposed Test Methods for
         Determining VOC of  Radiation Curable Materials"
   F.    Revised  Draft  EPA  Method  - "Determination  of Volatile
         Organic Content for Ultraviolet Radiation-Cured Coatings"
                               111

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                             ABSTRACT


   .Volatile organic  compounds are important  contributors to the
formation  of  ozone  in  photochemical  smog.    To  reduce  the
concentration  of ozone  in  the  environment,  the  Environmental
Protection  Agency  (EPA)   currently  regulates  volatile  organic
emissions from surface coatings.  Current  regulations require the
measurement of volatile organic content of surface coatings.  The
current EPA measurement method  (EPA  Method 24)  is not suited for
use with  surface coatings that  are  cured with  ultraviolet  (uv)
radiation. To meet its regulatory needs, the Office of Air Quality
Planning and  Standards has implemented the development  of a new
method  for  measuring  the  volatile  organic  content  of  uv-cured
coatings.

   The  objective of  this  project was to develop  a  method for
measuring total volatile  emissions from uv-cured coatings.  An EPA
Draft  Method, based on  an  American Society for  Testing  and
Materials  (ASTM) .subcommittee's    proposed  revisions  to  ASTM
D-2369-87, "Standard Test Method for  Volatile Content of Coatings"
was developed to meet this objective.

   The  new  EPA   Draft  Method  showed good  precision.  Absolute
standard deviations of triplicate samples  ranged from 0.09 to 1.62
percent for laboratory tests  of  ten coatings. The  coatings used in
the evaluation  consisted of  two  acrylic, five epoxy,  and three
thiol/polyene-based coatings. This method is not  suitable for uv-
based coatings that  contain  styrene  as a  reactive monomer.   The
accuracy of this method could not be evaluated due to the lack of
a reference material.
                                IV

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                             FIGURES

Number                                                      Page

   5-1  Exposure  Dependence  of  Pigmented  Sample
       with Method A  	13
   5-2  Exposure  Dependence  of  Method B   	15
   5-3  Exposure  Dependence  of  Black Low-VOC Material
       by EPA Draft Method	17


                              TABLES

Number                                                      Page

   5-1   Tests of ASTM Method A  	10
   5-2   Tests of ASTM Method B  	10
   5-3   Exposure Dependence of ASTM Method A  	12
   5-4   Exposure Dependence of Clear Coating
        by  ASTM  Method B    	14
   5-5   Exposure Dependence of Pigmented Coating
        by  EPA Draft  Method	16
   5-6   Low-VOC  Sample by ASTM Methods A and B
        with Increased Exposure 	  19
   5-7   Low-VOC  Sample by Modified ASTM  Method B
        with Cooling  Between 50 °C Oven  and UV Exposure     .  20
   5-8   Modified ASTM Method B with Acetone
        Evaporation at Room Temperature  	  21
   5-9   Comparison of Modified ASTM Method A
        with Modified ASTM  Method  B	22
   5-10 Comparison of Methods	25
   5-11 Acrylic-Based Coatings by  EPA Draft Method  ....  28
   5-12 Epoxy-Based Coatings by EPA Draft Method  	  29
   5-13 Polyester/Styrene-Based Coating
        by  EPA Draft  Method	30
   5-14 Thiol/Polyene-Based Coatings
        by  EPA Draft  Method    	31

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                 LIST OF ABBREVIATIONS  AND SYMBOLS
ABBREVIATIONS

ASTM           —   American Society for Testing and Materials
EPA            —   U.S. Environmental Protection Agency
UV             —   Ultraviolet light
VOC            —   Volatile organic content


SYMBOLS

Le             —   Evaporative weight  loss,  the  loss  in sample
                    weight after the evaporation of acetone added
                    to disperse the sample but before exposure to
                    uv light
Luv            —   Weight loss associated  with uv exposure  (may
                    be due to heating during processing)
Vtot            —   Total volatile loss
                                VI

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                         ACKNOWLEDGMENTS


     This  work has  been  supported  by  the  U.S.  Environmental
Protection Agency  under EPA contract  68D90055,  work assignments
1-70 and  1-81, and  68D10009,  work assignment  1-132.   EPA work
assignment managers were Lourdes L. Morales arid Lori T. Lay.

     We  would  like  to thank  Dr.  Leland H.   Carlblom of  PPG
Industries and Chairman of  the ASTM RadTech Science and Technology
Committee  for  his  assistance   in method  development  and  for
supplying test samples. We  also  would  like to thank Union Carbide,
W R Grace,  Lilly,  Radcure, and Henkel  Corporation  for supplying
test coatings.
                               VII

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                            SECTION 1


                           INTRODUCTION


     Volatile organic compounds are important contributors to the
formation  of  ozone  in  photochemical  smog.    To  reduce  the
concentration  of  ozone  in  the  environment,  the  Environmental
Protection  Agency  (EPA)   currently  regulates  volatile  organic
emissions from surface coatings.  Current regulations require the
measurement of volatile organic content of surface coatings.  The
current EPA measurement method  (EPA Method 24)  is not suited for
use with coatings that are cured with ultraviolet (uv) radiation.
To meet its regulatory needs, the Office of Air Quality Planning
and Standards has implemented the development of a new method for
measuring the volatile organic content of uv-cured coatings.

     In a traditional solvent-based coating,  much of the polymer
present in the final  film  is produced  during coating manufacture
(i.e., before  application)  and dissolved  in  an  organic solvent.
This solvent evaporates after application, leaving the polymer film
as the coating.   By contrast,  in  a uv-cured coating, most of the
polymer  is  formed  by uv  exposure  (curing)  after  application.
Because the unexposed uv-cured  coating is a low molecular weight
liquid, the coating may frequently be applied without  thinning with
organic solvents.  The use  of uv-cured  coatings  is  increasing in
industry because  *4) they increase  production rates, reduce energy
costs, and require smaller  processing facilities.  In addition, if
solvents  are  not  added,   switching   to  uv-cured   coatings  can
substantially lower volatile organic emissions. The increasing use
of uv-cured coatings  emphasizes the importance  of  an acceptable
method for measurement of volatile organic content.

     The  current  method   for  determining  the  volatile  organic
content of surface coatings,  EPA Method 24  (1J, actually determines
the volatile matter content.  Other volatiles, such  as water, are
determined  separately and  subtracted   from  the  volatile  matter
content  to  obtain  the  volatile organic content.    Currently
available uv-cured coatings  do  not  appear  to  have water  as a
component, and thus the volatile matter content of these coatings
is composed of volatile organic compounds.

     EPA Method  24  is not suitable for use with radiation-cured
coatings. Determination of  the volatile matter content by Method 24
involves  measuring the  weight loss  of  a coating  sample  after
heating   it  in   a   110 °C  oven  for   1 hour.     Ultraviolet
radiation-cured  coatings  form polymer  films  by  the uv-initiated
polymerization of reactive monomers present in the coating.  When
heated at 110 °C without  uv curing during Method 24,  some of these
reactive  monomers may  be  volatilized.   For  this  reason,  the
volatile emission values obtained using Method   24  may be higher

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than those experienced in actual usage.

     Preliminary inquiries with industry contacts revealed that the
American   Society   for  Testing   and  Materials  (ASTM)   has   a
subcommittee revising Method D2369 to make it suitable for uv-cured
coatings.  A copy of the ASTM draft revisions was obtained from the
subcommittee chairman, Dr.  Leland  Carlblom  of  PPG Industries.   A
visit was made to PPG Industries Research Center in Allison Park,
PA, to examine facilities and procedures used for testing uv-cured
coatings. The new ASTM Method A  (see Section  4.2.1) for uv-curable
coatings was demonstrated,  including  the  method used  to coat the
panels.    Ultraviolet exposure  equipment  was  demonstrated  and
revisions to ASTM D2369 for uv-cured coatings were discussed.

     This report describes  the review of  the ASTM method and the
development of a new EPA Draft Method for determination of volatile
matter  content from  uv-cured coatings.   The draft ASTM and EPA
methods  are  included  as  Appendices B   and  C,   respectively.
Responses to comments on the EPA  Draft Method are also included as
Appendix D.  A revised Draft EPA  Method, incorporating some of the
comments and other changes,  is included as Appendix F.

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                            SECTION 2


                     SUMMARY AND CONCLUSIONS
     Two proposed ASTM methods  (ASTM Method A and ASTM Method B)
for determining the volatile organic content of uv-cured coatings
were evaluated.   Results of  tests on a  pigmented acrylic-based
coating by these methods showed higher than expected total volatile
levels.  Much of this was  later attributed to inadequate curing,
although curing was performed at the manufacturer's suggested light
intensity, conveyor-belt feed rate, and number of passes.

     Modifications were made  to improve  these  methods.  The most
important of these modifications was the development of a test for
extent of cure.  Comparison of the total volatile loss at different
lengths  of  exposure  provides an  easy and  inexpensive  means for
testing  the  extent of cure.   During  this study, the  length of
exposure of a sample was  increased by slowing down the conveyor-
belt feed rate or by increasing the number of passes through the uv
apparatus.  Other modifications included eliminating the 50 °C oven
(in ASTM Method B) for evaporation, of solvent and performing the
initial  evaluation of  the coating at  two and  four times  the
manufacturer's suggested number of passes.

     A  new  EPA Draft Method  for measuring  the volatile organic
content  of  uv-cured  coatings  was prepared  based  on  the modified
ASTM  Method B.    This   new  EPA   Draft  Method  includes  the
modifications  described  above.    The new method  showed  good
precision.  Absolute  standard  deviations  of triplicate  samples
ranged  from 0.09  to  1.62  percent for  laboratory tests of  ten
coatings.

     The coatings used in the precision evaluation consisted of two
acrylic, five epoxy,  and three thiol/polyene-based coatings.  The
test coatings had total volatile organic  content between -l.l and
29.8 percent, as determined by the EPA Draft Method.   This method
also should be suited for coatings with higher volatile contents.
Earlier  work,  using  essentially  the same  method, but  performed
before  the  EPA  Draft  Method  had  been  prepared,  showed  good
precision  (absolute  standard  deviation of  triplicate  samples of
0.2 percent)  for  an  acrylic-based  coating with  total  volatile
organic  content of 61.4 percent.    Presently,  this method is not
suitable for uv-based coatings that contain styrene as a reactive
monomer due to its evaporation at room temperature.

     The accuracy of  this  method could not be evaluated due to the
lack of  a reference material.

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                            SECTION 3

                         RECOMMENDATIONS
     The  EPA Draft  Method  for  volatile organic  content  from
uv-cured coatings has  shown good results  in  laboratory testing.
Polyester/styrene coatings require  additional  testing to resolve
problems.  An interlaboratory  test  of  the EPA  method  (using a
variety of different coatings) should be performed to determine  its
repeatability and reproducibility.

     Dr. Joseph Knoll with the Office of Research and Development
is  undertaking  this  initiative.    In addition  to  the  above
recommendations an assessment of the ultraviolet-cured inks will be
conducted.

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                            SECTION 4



                     EXPERIMENTAL PROCEDURES
4.1  EXPERIMENTAL APPARATUS

4.1.1  Sample Curing system

     All samples in this study were cured using a "Mini-Laboratory
Conveyor" system (model C1006A, American Ultraviolet Company, Murry
Hill, NJ) .  This system  consists  of  a 6-inch wide quartz mercury
arc lamp, which can be operated  at input power levels of 300, 200,
or 125 W/-in. (i.e., 1,800, 1,200,  or  750 W for the 6-inch tube).
The  lamp  output power was not  measured.   All exposures  in this
study were done at either 300 or 200 W/in. input power.  The lamp
is mounted  at  a  fixed   distance  over  a  Nomex-coated  fiberglass
conveyor  belt.   The belt speed (conveyor-belt feed  rate)  can be
varied from approximately 0 to 100 ft;/min.

     This apparatus provides considerable flexibility for adjusting
the sample exposure length.  The total exposure of a sample could
be increased by:

     •  Increasing  the lamp wattage,
     •  Decreasing  the conveyor  feed  rate (i.e.,  halving the feed
        rate would  double the  length  of  exposure),
     •  Increasing  the number  of passes  through the apparatus.

Each  method for  varying  the  length of  exposure  has different
advantages.   Varying the lamp wattage is very efficient; however,
there is no easy relationship between the input power  level (i.e.
lamp wattage)  and the uv light output at the specific wavelengths
that cause  the  coating  to cure.  Slowing  down the conveyor belt
feed rate increases the  length  of uv exposure but also increases
the thermal  exposure (and thus the final temperature)  of the sample
during curing.  Increasing the number of passes under  the lamp is
relatively straightforward and fairly rapid (each pass takes less
than 30 seconds at typical conveyor belt feed rates).


4.1.2  Drawdown Rod

     The ASTM Draft Method A, described in Section 4.2.2,  uses a
drawdown rod to place a  uniform  film  coating on the test panel.  A
drawdown  rod  is a metal rod  that has been tightly  wound  with a
single thickness of wire.  The grooves  formed by the wire provide
a  cavity of  uniform  thickness along  the  outer  surface  of  the
drawdown rod.   When the coating is pulled across the panel with the
drawdown  rod,   thin  stripes  of coating are left  on the surface
under the cavities in the outer surface of the drawdown rod.  The

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stripes quickly flow together, leaving a film of uniform thickness.
A considerable degree of skill is required to pull the rod across
the panel  at  the  correct  rate  and  with the correct  pressure.
Coating  test  panels  in this manner  is  common  in  many coating
research laboratories, but skilled personnel may not be available
in other  laboratories.   All  panels  were coated using  a Size 10
drawdown rod (Model AP-JR-10, Paul N.  Gardner Co.,  Pompano Beach,
FL) .


4.1.3  Other Laboratory Equipment

     Two balances were used in this study (Torbal model EA 160 and
Mettler model AT400).  Both are single-pan analytical  balances with
a resolution of ± 0.0001 g that have been calibrated with weights
traceable to the National Institute  of  Standards  and Technology
(NIST).   A Blue M model SW-17TA-1 natural convection drying oven
was used to  heat samples in the  study,  and a  Fisher vacuum oven
(used at atmospheric  pressure with forced  air flow)  was used to
remove acetone from the ASTM.Draft Method B samples at 50 °C.

     Standard  aluminum  coating test panels  (either 3 by 8 in. or
4 by  6  in.)  were  used  in  ASTM  Method  A.   Disposable  aluminum
weighing dishes  (58 mm  diameter)  were used  for ASTM Method B and
the EPA Draft Method.  Disposable polyethylene pipettes were used
for sample handling in  all  methods.   Acetone (ACS reagent grade)
was used to  disperse samples in  ASTM Method B and the EPA Draft
Method.
4.2  DESCRIPTION OP ASTM METHODS

     The proposed ASTM procedure for determining VOC of radiation
cured coatings, (Appendix B) is comprised of two methods: Method A
for  use with  materials  with  less  than  3  percent  volatiles  and
Method B for use with all materials.
4.2.1  Method A

     Method A  involves  placing a uniform coating thickness on  an
aluminum test  panel.   This is done by placing excess material  on
the top of the panel and pulling the coating across  the panel with
a drawdown rod to achieve a uniform film thickness.   Excess coating
on the sides or  bottom of the test panel is removed with a clean
wipe.  The coated panel  is weighed to determine the sample weight
and then exposed to uv radiation for curing.  The weight  loss, upon
curing is referred to as  the  "Processing VOC"  (%).  The  now-cured
sample is then placed in an oven at 110  ± 5  °C and reweighed after
cooling.   The weight  loss  due to  heating  is  referred  to  as
"Potential VOC"  (%) .  The total  volatiles (total VOC) is given  as
the sum of the "Processing" and  "Potential" VOC values.

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4.2.2  Method B
              «
     Method  B  (for  all  samples,  including  high VOC  samples)
involves  adding approximately .3 mL  of acetone  to  an  aluminum
weighing dish.  The sample is added  from a preweighed pipette, and
the sample  weight  is obtained as the difference  in  the pipette
weight before and after the sample is dispensed. The sample dish is
swirled to disperse the coating.  The sample is heated  at  50  °C for
30 minutes and then exposed to uv radiation for curing. The weight
loss  measured .after  curing  is  referred to  as  the  "Processing
VOC"(%).    This includes los"s of volatiles both  in handling and
during the uv-curing  process. The now-cured sample  is then placed
in an oven at 110 ± 5 °C and reweighed after cooling.  The weight
loss due  to heating  is referred to as  "Potential VOC"  (%) .  The
amount of total  volatiles  (total  VOC)  is given as the sum of the
"Processing" and "Potential" VOC values.


4.3  TESTS USING ASTM METHODS

     A series of representative acrylic-based samples were analyzed
by ASTM Methods A and B.   Results are discussed in  Sections 5.1.


4.4  MODIFICATIONS TO ASTM METHODS

4.4.1  Method A

     Initial tests of Method A suggested that  the  samples were not
adequately cured.  To ensure  adequate curing,  Method A  was modified
to  provide  a  longer uv exposure  than the  recommended by  the
manufacturer.    This was done by varying  the conveyor-belt feed
rate or by passing the sample through the exposure  apparatus more
than once (i.e., two  passes for twice the uv exposure, four passes
for  four times  the  uv  exposure,  etc.).   To  avoid  unnecessary
heating of the samples at low conveyor-belt feed rates, most  of the
high-exposure samples were exposed with multiple passes.  Results
are discussed in Section 5.2.1.
4.4.2 Method B

     Several  modifications to ASTM  Method B  were made.   These
include, increasing the length of uv exposure over the  specified by
the manufacturer,  cooling  between  the 50 °C oven and uv-exposure
steps,  and  finally  the  elimination  of  the  50 '°C  oven  for
evaporation of solvent.  Results are discussed in Section 5.2.2.

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4.5  DEVELOPMENT OF EPA DRAFT METHOD

     An EPA Draft Method was  prepared based on our experience with
the  ASTM Methods  and . our  modifications to  these  methods.  The
modified ASTM Method  B  was  chosen as the basis  of  the EPA Draft
Method.  Features of the EPA Draft Method include:

     •  Inclusion of cure test
     •  Elimination of 50 °c  oven for evaporation of solvent
     •_  Beginning the  evaluation of coating at two and four times
the manufacturer's suggested length of uv exposure.


4.5.1  Inclusion of Cure Test

     Based  on  results that showed total  volatile levels reduced
with increasing the length of uv exposure until adequate cure was
reached   (Section  5.2.2.1),   a   cure  test   was  developed  and
incorporated into  the EPA Draft Method.   This involved analyzing
the samples at an initial length of exposure and twice the initial
length  of  exposure   (keeping constant the  light  intensity  and
varying  either  the  conveyor-belt  feed  rate or  the  number  of
passes).    If  the total  volatile losses  disagree by  more than
1 percent  (absolute),  the sample is  not cured  and  the process
should be repeated at a  longer  exposure.


4.5.3   Elimination of 50 °c  oven

     The use of a 50  °C  oven was deleted from the EPA Draft Method.
Instead,  the  EPA Draft .Method  allows-  the acetone to vaporize at
room temperature in a fume hood  or other well-ventilated space for
30 minutes.


4.5.4   Evaluation  of Coating at  Twice  Manufacturer's Suggested
Exposure

     Because the uv-cured coatings appeared to be  insensitive to
overexposure,   the  EPA  Draft   Method  begins  with  twice  the
manufacturer's  suggested length of exposure.   This increases the
likelihood  of  obtaining  adequate  cure on the  sample  initial uv
curing  exposure.


4.6  EVALUATION OF SAMPLES USING  EPA DRAFT METHOD

     Acrylic,  epoxy,  polyester/styrene,  and thiol/polyene-based
coating samples were  tested  by  the EPA Draft Method.  The results
are  discussed  in Section 5.4.

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                            SECTION 5

                     RESULTS AND  DISCUSSION
5.1  RESULTS USING ASTM METHODS

     The draft revisions to ASTM D2369 (Section 4.2  and Appendix B)
consist of two methods: Method A for low-VOC materials (less than
3 percent volatiles) and Method B for all materials.  The results
from  each method  are discussed in  Sections  5.1.1 and  5.1.2,
respectively.


5.1.1  Results Using Method A

     Initial  tests  of ASTM  draft Method  A were  performed  with
acrylic samples 'supplied  by PPG  Industries.   These samples had
previously been tested by ASTM in an interlaboratory comparison.
Neither sample tested by  Method A  had added solvents and the
samples were regarded as low-VOC coatings.  Tests of  these samples
at the manufacturer's suggested curing conditions  (light intensity,
conveyor belt feed rate, and  number of passes), (Table 5-1)  showed
higher potential and total VOC  than expected, based on information
from the manufacturer.

     Some degree of skill and  practice  was required to develop a
uniform coating  by using the  drawdown  bar.   Although preparing
films  in  this  manner  is  commonly  done  in  industrial  coating
laboratories,   less  experienced  laboratories  may  experience
difficulties. Overly  thick  coatings may have  difficulty curing.
Pigmented coatings  are especially subject  to this  problem  due to
poor .uv penetration.


5.1.2  Results Usincr Method B

     Tests of  ASTM Draft  Method  B  were performed with  high VOC
clear  acrylic-based samples  supplied  by  PPG  Industries.    All
samples  were  exposed at  the manufacturer's  suggested  curing
conditions (light intensity,  conveyor belt feed rate,  and number of
passes).  These samples had  previously  been tested by ASTM in an
interlaboratory comparison.  Both samples  had added solvents and
would be regarded as high-VOC coatings.  Results for  test Method B
(Table 5-2)  showed good precision.

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TABLE 5-1 TESTS OF ASTM METHOD A
Sample
Color
Lamp power (Watts per inch)
Feed rate (feet per minute)
Number of passes
% Processing (average)
% Processing (standard deviation)
% Potential (average)
% Potential (standard deviation)
% Total (average)
% Total (standard deviation)
TABLE 5-2 TESTS OF ASTM
Sample
Color
Feed Rate (ft/min.)
Number of passes'
% Processing (average)
% Processing (standard deviation)
% Potential (average)
% Potential (standard deviation)
% Total (average)
% Total (standard deviation)
PS1A
clear
200
51
1
0;4%
0.3%
6.1%
1.0%
6.5%
1.2%
METHOD
PS4B
Clear
19.6
1
60.0%
0.2%
1.8%
0.2%
61.8%
0.3%
PS3A
black
200
24
1
0.9%
0.6%
11.2%
3.4%
12.0%
3.1%
B
PS5B
Clear
19.6
1
29.8%
0.3%
1.9%
0.4%
31.8%
0.4%
* Lamp power = 200 W/in.
               10

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5.2  MODIFICATIONS TO ASTM METHODS

     The initial  tests  of Method A showed  higher measured total
volatiles than those expected based on  manufacturer's data.  For
this reason,  attempts were  made to modify Method A  to provide
better results.   Samples tested by Method  B  showed higher total
volatiles than the  identical sample tested by Method A  (Section
5.2.2.2).   Thus,  attempts to modify  Method B  to provide better
results  were  also made.   These  modifications are  described in
Sections 5.2.1 arid 5.2.2.
5.2.1  Method A

     In the tests of Method A, the pigmented sample, PS3A, showed
much higher total VOC than  the  clear  sample,  PS1A.   In addition,
the PS3A sample showed poor  adhesion and softness, which are signs
of poor curing.   It was felt that the higher measured total VOC for
the PS3A  sample  might be also due to  undercuring resulting from
underexposure.   For  these  reasons,  the  exposure  dependence  of
Method A  was  investigated  by  repeating Method  A with  the PS3A
sample at different lengths  of exposure.  The results are shown in
Table 5-3 and Figure 5-1.  There  was a noticeable  increase in both
potential and total VOC  for  coatings that were inadequately cured.
More  important  was  that both  potential  and  total  VOC  became
constant at longer uv exposures.  This enabled the development of
an easy  test  for adequate cure  (Section 4.5.1).   All subsequent
work done  using  Method  A was done with uv-exposures  longer than
those recommended by the coating manufacturer.


5.2.2 Method B

     Several  modifications  to ASTM Method B  were made.   These
include, increased uv length of exposure, cooling between the 50 °C
oven and uv-exposure step, and finally the elimination  of the 50 °C
oven for evaporation of solvent.

5.2.2.1 Increased UV-Exposure—  Method B is not usually used for
pigmented  low-VOC  samples.   The only  available high-VOC samples
were  clear and  the  uv-exposure dependence  of a  clear  high-VOC
sample was tested first  (Table 5-4 and  Figure  5-2).  No uv-exposure
dependence was seen for  this sample.   This  is consistent both with
the thinner coat (because approximately 30 percent of the sample
was volatiles, less coating  material was left on the sample pan) as
well as the use of a clear material which is more easily cured. For
this  sample,  adequate  cure was obtained  even at the  shortest
exposure tested.

     Based on the results of the exposure dependence of ASTM Method
A, we immediately  increased the  length   of  exposure of  future
Method B  tests  of the pigmented PS3A sample to  those  needed to
                                                         •
                                11

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        TABLE 5-3 EXPOSURE DEPENDENCE OF ASTM METHOD A
Sample
Feed Rate (ft./min. )
Number of Passes1
Exposure Indexb
% Processing
% Potential
% Total
PS3A Black Acrvlic-Based Samole
25.0
1
0.04
0.7%
9.1%
9.8%
25.4
2
0.08
0.4%
5.9%
6.3%
12.3
1
0.08
0.2%
4.9%
5.1%
25.4
4
0.16
0.7%
3.6%
4.3%
25.4
8
0.32
0.4%
3.1%
3.5%
25.1
16
0.64
1.9%
2.3%
4.2%
1 Lamp Power = 200 W/in.
b Exposure Index = (number of passes) / (feed rate (ft./min.))
                                 12

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   10.00% -r
    9.00% -r
    8.00% --
    7.00% --
    6.00% --
I   5.00% -- '
o
    4.00% -r
    3.00% --
    2.00% --
    1.00% -r
                              PS1A Clear Acrylic-Based Sample
    0.00%
                                                          — a—  % Processing
                                                          —<:^— % Potential
                                                          ••«••% Total

          0.00       0.10
0.20
0.50       0.60
                  0.30      0.40
                  Exposure Index
Figure 5-1 Exposure Dependence of ASTM Method A
0.70
                                          13

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Table 5.4 EXPOSURE DEPENDENCE OF CLEAR COATING BY ASTM METHOD B
Sample
Feed Rate (ft/min)'
Number of Passes
Exposure Indexb
% Processing
% Potential
% Total
PS5B Clear Acrvlic-Based
25.2
1
0.04
29.8%
1.8%
31.5%
25.2
2
0.08
30.7%
1.5%
32.2%
12
1
0.08
29.8%
1.2%
31.0%
25
4
0.16
30.4%
1.4%
31.9%
Coating
25
8
0.32
30.0%
1.5%
31.5%

25
16
0.64
30.2%
0.9%
31.1%
    1 Lamp Power = 200
    b Exposure Index = Number of passes / feed rate
                                14

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 35.00%  -r
 30.00%  4-
                              PS5B Clear Acrylic Based Coating
 25.00%  4-
20.00%
o
=
«
15.00%
                                                      % Processing
                                                      % Potential
                                                    • % Total
10.00%  4-
 5.00%  4-
0.00%
       0.00       0.10
                             0.20      0.30      0.40      0.50      0.60      0.70
                                       Exposure Index

               Figure 5-2 Exposure Dependence of Clear Coating By ASTM Method B
                                       15

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TABLE 5-5  EXPOSURE DEPENDENCE OF PIGMENTED COATING BY EPA~
                       DRAFT METHOD
Sample
Date
Feed rate (ft/min)
Passes
Exposure Index*
Evaporation loss (LJ
Processing Loss (L.J
Total Volatiles (LJ
PS3A-
Black Acrylic
7/9/1992
25.0
2
0.08
0.3%
0.4%
13.0%
25.0
4
0.16
-0.7%
0.9%
9.2%
-Based Coating
7/10/1992
24.9 24.9
8 16
0.32 0.64
-1.4% -5.6%
1.3% 3.1%
6.0% 5.9%
      *  Exposure Index = Number of passes / Feed Rate.
                             16

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  14.00%  T
  12.00%  --
   10.00%  --
   8.00%  --
o
   6.00%  --
   4.00%  -r
   2.00%  --
   0.00%
                             PS3A Black Acrylic-Based Sample
                     •x- - Processing Loss (Luv)
                     -*- - Tolal Volatlles (Vtot)
                                         \
         0.00      0.10
0.20      0.30       0.40       0.50      0.60      0.70
          Exposure Index
      Figure 5-3 Exposure Dependence of Black Low-Voc Material by EPA Draft Method
                                         17

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obtain proper cure by ASTM Method A.  An exposure dependence study
of Method B with pigmented samples was not made.  However, the data
obtained during testing (Table 5-5 and Figure 5-3) of the pigmented
acrylic-based sample PS3A by the EPA Draft Method (which is based
on modified  ASTM  Method B)  shows  clear  dependence of  the total
volatile results on the length of uv-exposure.  This demonstrates
the need for a  cure  test  for samples  tested by  Method B.   Such a
test (Section 4.5.1) was incorporated into the EPA Draft Method.


5.2.2.2 Introduction of Cooling between 50 °C Oven and DV-exposure-
   Since both Method A and Method  B can  be used to measure total
volatiles, a comparison of the two methods was tried. The pigmented
acrylic-based  sample  PS3A  that  was  previously  tested   by  the
modified Method A was tested with the modified Method B (i.e.,
modified  by  using   longer  exposure  than  the  manufacturer's
recommended).  The pigmented sample PS3A  was chosen for test since
it would  be the most  affected  by the smaller  surface  area  (and
resultant thicker coating) in Method B.  The results are shown in
Table 5-6.   The  total  VOC obtained  by  modified Method B  are
noticeably higher than those by modified Method A.    In addition,
the precision of replicate analyses is poorer by  modified Method B.


     One possible cause of the  higher total volatile  levels by
modified Method B was excessive  heating during processing.  During
uv irradiation, the samples are also heated by energy produced by
the lamp.  Modified Method B does not specify cooling the  samples
between the 50  °C oven and uv-exposure step; it was felt that the
samples may have reached excessive temperatures due  to heating  from
both the oven and  uv-exposure. For this reason, the modified Method
B analyses were repeated allowing adequate time for  cooling to  room
temperature before uv-exposure  (in a sealed desiccator to  prevent
moisture accumulation).  The results  for  twp coatings are given in
Table 5-7.  Allowing the  samples to cool between removal from the
50 °C  oven and uv  exposure not  only improved the  precision of
modified Method B but  also provided lower total VOC measurements.
However, for sample PS3A,  the Total VOC values from modified Method
B with the cooling step were still approximately 40 to 50  percent
higher than those of the  modified Method A.


5.2.2.3  Elimination  of  50  °C  oven for  evaporation  of solvent—
  Visual observations  during Method B indicated that most, if not
all, of the acetone had evaporated within 10 minutes of dispensing
 (i.e., while the samples were dispersed).   This  indicated that the
heating  of samples to  50 °C might be unnecessary and  that  this
oven-heating  could  account  for  some of  the increase  in VOC  over
those determined  by  Method  A.   Sample testing was repeated using
modified Method B with acetone evaporated by setting the  samples in
a  fume-hood for 30 minutes instead  of using a 50 °C  oven.   The
modifications  to  Method  B also  incorporated longer exposure  than

                                18

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TABLE 5-6 LOW-VOC SAMPLE BY ASTM METHODS A AND B WITH
                   INCREASED EXPOSURE
Sample
Method
Feed Rate (ft/min )
Number of Passes*
Exposure Index1*
% Processing
% Processing (standard deviation)
% Potential
% Potential (standard deviation)
% Total
% Total (standard deviation)
PS3A
A
25.4
8
0.32
0.4%
0.1%
3.1%
0.9%
3.5%
0.9%
Black Acrvlic-Based Sample
A
25.1
16
0.64
1.9%
0.6%
2.3%
1.4%
4.2%
1.4% '
B
25.1
8
0.32
5.3%
2.7%
4.1%
0.9%
9.4%
3.3%
B
25.1
16
0.64
3.8%
0.5%
3.9%
1.0%
7.8%
1.5%
 1  Lamp Power = 200 W/in.

 b  Exposure Index = (number of passes) /[feed rate (ft/min)]
                            19

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TABLE 5-7 LOW-VOC SAMPLE BY MODIFIED ASTM METHOD B WITH
        COOLING BETWEEN 50 °C OVEN AND UV EXPOSURE
Sample
Color
Feed Rate (ft/min )
Number of Passes'
Exposure Index*1'
% loss in 50 °C oven
% loss in UV exposure*1
% Processing
% Processing (standard deviation)
% Potential
% Potential (standard deviation)
% Total
% Total (standard deviation)
PS3A
Black
25.1 25.2
8 16
0.32 0.64
2.6% 3.1%
0.2% 0.2%
2.8% 3.3%
0.2% 0.1%
3.0% 2.3%
0.6% 0.2%
5.8% 5.5%
0.8% 0.2%
RT1A
Clear
25.2
8
0.32
-0.2%
-0.1%
-0.3% •
0.5%
1.1%
0.6%
0.8%
1.0%
      * Lamp Power = 200 W/in.
      b Exposure Index = (number of passes) / [feed rate (ft/min)]
      c Samples exposed at greater than manufacturer's suggested
      exposure levels.
      d % Processing = % UV loss + % loss in 50 °C oven.
                                20

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TABLE 5-8  MODIFIED ASTM METHOD B WITH ACETONE EVAPORATION AT
                         ROOM TEMPERATURE
Sample
Color
Feed rate (ft/min )
Number of Passes'
Exposure Indexb
% Loss before UV Exposure
% Loss before UV Exposure (std. dev.)
% Loss during UV Exposure
% Loss during UV Exposure (std. dev.)
% Processing0
% Processing (standard deviation)
% Potential
% Potential (standard deviation)
% Total
% Total (standard deviation)
RT1A
Clear
25.2
16
0.64
-0.2%
0.1%
-0.2%
0.0%
0.0%
0.1%
0.8%
0.5%
0.8%
0.5%
PS4B
Clear
25.2
16
0.64
60.1%
0.2%
0.2%
0.0%
60.3%
0;2%
1.1%
0.0%
61.4%
0.2%
PS3A
Black
25.2
16
0.64
2.8%
0.3%
0.5%
0.1%
3.3% .
0.3%
2.9%
0.4%
6.2%
0.7%
25.2
16
0.64
3.1%
0.3%
0.2%
0.0%
3.3%
0.4%
2.6%
0.4%
6.0%
0.1%
      * Lamp Power = 200 W/in.
      b Exposure Index = (number of passes) / [feed rate (ft/min)]
      e % Processing includes losses both before and during UV-exposure
                                  21

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 TABLE 5-9  COMPARISON OF MODIFIED ASTM METHOD A WITH MODIFIED
                             ASTM METHOD B
Method11*
Feed Rate
(ft/min)
Number of
Passes
% Processing
%Potential
% Total
AO*
D
25.4
4
0.7%
3.6%
4.3%
25.4
8
0.4%
3.1%
3.5%
25.1
16
1.9%
2.3%
4.2%

Avg,
1.0%
3.0%
4.0%
25.2
16
3.3%
2.9%
6.2%
25.2
16
33%
2.6%
6.0%
T-
Test
Prob/
Avg,
3.3% 1.0%
2.8% 0.5%
6.1% 1.0%
Different
at 95%
Conf.?

Yes
No
Yes
*  Both methods were done with exposures greater than those recommended by the
manufacturer.
"  Sample is PS3A - Black Acrylic Coating
c Method B samples were performed without 50 8C heating
* T-Test is for means of method A and method B assuming unequal variances.
                                     22

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those recommended  by  the manufacturer. The results  are shown in
Table 5-8.  The values at room temperature are  essentially the same
as those with  the  50  °C  oven.  This  shows  that the use of a 50 °C
oven is not necessary to evaporate the acetone.

     Comparison  of results  for  modified  Method A  (modified by
longer exposure)  and modified Method B (modified by longer exposure
and  elimination  of  50  °C  oven)   using   the pigmented coating
(Table 5-9)  show that the loss on  heating  (potential  loss)  is
similar for the  two methods.   The processing  loss,  however, is
lower in modified Method A.  Since Method A has the sample pulled
to a thin  film before the  sample is weighed,  some volatiles that
may be present in the  coating may evaporate and not be included in
the initial sample weight.  This would cause  modified Method A to
show a lower measured processing loss compared  to modified Method B
under similar uv curing conditions exposure conditions.


5.3  DEVELOPMENT OP EPA DRAFT METHOD

     An EPA Draft Method was prepared based on our experience with
the ASTM  Methods  and  our  modifications  to  these  methods.  ASTM
Method B was chosen as the basis of the EPA Draft Method for the
following reasons:

     •  Because Method A  is only for low-VOC materials, a  screening
        test is  required to  determine  whether the  coatings are
        suitable  for use  with Method  A.  For this  reason, Method B
        would  have  to be  developed  if  only  to  provide  such  a
        screening test.

     •  The  trial  tests   of  a  pigmented  low-VOC  coating  with
        Method B  showed good  precision with only slightly higher
        total VOC than with Method  A.
5.4  SUMMARY OP EPA DRAFT METHOD

     The  EPA  Draft Method,  included  as  Appendix  C,  involves
triplicate  analyses  at each of two  (or  more)  uv-exposure levels
(initially  at twice and four times the manufacturer's recommended
length of exposure).  It is recommended that the length of exposure
be  increased  by  increasing  the  number of  passes  through the
exposure apparatus rather than by reducing the feed rate to  avoid
additional  heating of the sample(s) at low feed rates.

     Each   analysis  involves   dispensing  the  coating  from  a
preweighed pipette into a preweighed pan and determining the sample
weight as the  difference  in  the weight of the pipette before and
after  dispensing  the  sample.   The  sample is then dispersed in
acetone, which is  evaporated  at room temperature to leave a uniform
film in the weighing pan.  The sample is weighed to determine the

                                23

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loss resulting from handling at room temperature  (Le).  The sample
is then cured by exposure to uv light at twice the manufacturer's
recommended exposure  and weighed to determine  the uv-processing
loss (LUV) .   The cured sample  is heated  in  an oven at 110 ± 5 °c
for one hour.  .The  sample  is then  weighed to determine the total
volatile emission (Vtot) .

     If the average of the total volatile emissions  (Vtot) of the
samples exposed at twice the manufacturer's recommended number of
passes do not agree  to within ±1 percent of those at four times the
manufacturer's number of passes, the process is repeated at twice
the last exposure (i.e., eight times the manufacturer's number of
passes) until agreement of  ±1 percent  is reached.

     Differences between the  draft  ASTM  Method  and the EPA Draft
Method can be summarized as follows:

     •  Elimination  of Method A.
     •  Use  of room temperature rather than 50 °C for evaporation
•  •      of solvent.
     •  Exposure at  two and four times the manufacturer's suggested
        number of  passes.
     •  Incorporated cure test (i.e., doubling the  exposure should
        not   change  total   volatiles  by  more  than  1 percent,
        absolute).


5.5 COMPARISON OF METHODS

     Since  much of  the testing involved  analysis  of  the black
acrylic-based  sample  PS3A,  it is possible to compare all of the
methods tested in this project (Table 5.-10).  These methods are as
follows:
     1) ASTM  Method A  (at manufacturer's recommended  length of
        exposure).
     2) Modified ASTM Method  A (at  increased length  of exposure).
     3) ASTM  Method B  (at manufacturer's recommended  length of
        exposures).
     4) Modified ASTM Method  B (at  increased length  of exposure).
     5) Modified ASTM Method B (at increased length of exposure and
        with  cooling between 50  °C  oven).
     6) Modified ASTM Method B (at increased length of exposure and
        with  room temperature evaporation of acetone).
     7) EPA Draft Method (the same as 6 above, but with a cure  test
        to  ensure adequate curing).

     The unmodified ASTM Methods (1 and 3,  above)  show the poorest
precision   and the  highest  measured  total  volatiles.    The
modifications  to increase  uv-exposure decrease the measured total
volatiles and increase  the precision.   The modified Method A  (2,
above)  above shows lower  measured  total  volatiles than modified
Method  B  (6,  above) or  the  EPA Draft Method  (which is  based on

                                24

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             TABLE 5-10  COMPARISON OF METHODS
Sample
Method
PS3A Black Acrvlic-Based

Increased Exposure
Cooling
between
A*
No
NA«
Ab
Yes
NA
Be
Yes
No
B'
Yes
Yes
Coatine
fi-
Ves
Yes
EPA
Draft'
Yes
NA
50 °C Oven and UV-
exposure
Evaporation at Room
Temperature
NA
NA
No
No
Yes
Yes
% Processing
% Potential
% Total
0.9%
11.2%
12.0%
1.9%
2.3%
4.2%-
3.8%
3.9%
7.8%
3.3%
2.3%
5.5%
3.3%
2.8%
6.1%
3.1%
2.8%
5.9%
1 Table 5-1
k Table 5-3 (16 passes at 25.1 ft/min)
"Table 5-8 (16 passes at 25.2 ft/min)
4 Table 5-7 (16 passes at 25.2 ft/min)
* Average of two analyses (Table 5-9)
'Table 5-11, % Total = V^ , % Processing = L^, % Potential = Vw - L.
• NA a Not Applicable
                                 25

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Method B).  The lower measured total volatiles seen with modified
Method A  (2,  above)  may be  due  to losses  of  volatile compounds
before weighing the sample (i.e., while coating the panel).

     Comparison of  a clear  high volatile  acrylic-based coating
(PS5B) by  ASTM Method B  (Table  5-2 at  manufacturer's suggested
exposure and Table 5-4 at  increased exposures)  and the EPA Draft
Method  (Table 5-11)  show  that  the  ASTM Method  B (at  both  the
manufacturer's and higher exposure)  gives a  slightly higher result
(31.6%) than the EPA Draft Method (29.8%). This slight  increase in
the ASTM Method B results may be  due to volatilization  of reactive
species  during  the 50 °C oven before  uv-curing.   The EPA Draft
Method,  with  its  evaporation of  acetone  at  room temperature will
tend to minimize this volatilization.

     Due to the high measured total volatile levels and the poor
replicability,  the use  of   either  Method A or Method B without
modification  to  increase length of exposure is not recommended.
The use  of a  cure test  (Section  4.5.1)  is highly recommended and
has been incorporated into the EPA Draft Method.
5.6  TESTS OF MATERIALS WITH EPA DRAFT METHOD

5.6.1  Acrylic Coatings

     A  variety  of  acrylic  coatings  were  tested  during  the
development of the EPA Draft Method.  Of these, two coatings were
selected  for  analysis by  the current  version of the  EPA Draft
Method.   The  results  of  these analyses, presented in Table 5-11,
are  good,  with  standard   deviations   for  Vtot  below   l percent
(absolute).  The reason for negative evaporative losses  for sample
PS3A is not known.


5.6.2  Epoxy Coatings

     A total of five uv-cured epoxy-based samples obtained from two
different manufacturers (Lilly and Union Carbide)  were analyzed  by
the EPA Draft  Method.  The results are summarized in Table 5-12.
The  results are  good with standard  deviations of Vtot   below
2 percent  (absolute).  A noticeable  feature of  the epoxy coatings
is the occasional  negative value of Vtot.   This is due  to weight
gain from atmospheric water,  which results  in  negative  losses for
low-VOC coatings.

5.6.3  Polyester/Styrene coatings

     Only  one polyester/styrene based  coating  was available for
testing.   Results  are presented in Table 5.13.  Although several
attempts were  made, it was not possible to achieve two  runs that
met the cure  criteria  (i.e.,  agreement of Vtot  at one exposure  to

                                26

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within  1  percent   (absolute)  of  Vtot  when run  at  double that
exposure).  This sample was  also the most viscous sample tested,
which was difficult to dispense (due to high viscosity).  Although
it was difficult to dispense the sample,  once dispensed, the  sample
was  easily  dispersed .because  it  dissolved  well   in  acetone.
Problems  also  may  have been   due to evaporation  of the styrene
monomer at room temperature.  Differences in room temperatures on
different  dates may  have  led  to  differing  values  for  Vtot.
Additional  studies should  be  performed  on similar  coatings  to
determine the causes of the problems.


5.6.4  Thiol/Polyene Coatings

     Three  thiol/polyene-based coatings  were  tested by  the EPA
Draft Method.   The results,  given in Table 5-14,   are good with
standard deviations of Vtot  less than 1.5 percent  (absolute).
                                27

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 TABLE 5-11 ACRYLIC-BASED COATINGS BY EPA DRAFT METHOD
Manufacturer
Coating
Color
L.
Standard deviation of L(*
u
Standard deviation of Lw
vtt
Standard deviation of Vw
Max passes

PS3A
Black
-5.6%
3.0%
3.1%
1.1%
5.9%
0.4%
16
PPG
PS5B
Gear
27.2%
0.1%
0.2%
0.2%
29.8%
0.1%
4
'All standard deviations are absolute

* The maximum number of passes is the minimum number of passes to obtain Vk
to within 1% (absolute).  The minimum number of passes for the method is 4.
                              28

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         TABLE 5-12 EPOXY-BASED COATINGS BY EPA DRAFT METHOD    ^
Manufacturer
Coating*
Le
standard deviation
ofL/
Luv
standard deviation
of IV
Vtot
standard deviation
of VJ-
Max passes6
Union Carbide
17969-72-1
-0.4%
0.5%
-0.2%
0.1%
-0.6%
0.5%
4
17969-72-2
-2.5%
0.3%
0.0%
0.3%
-1.1%
1.4%
4
17969-72-3
-0.4%
0.2%
0.1%
0.1%
1.8%
0.3%
8
Lilly
42074 >5%
voc
8.0%
0.8%
0.5%
0.8%
11.1%
1.6%
8
42074 - 0%
VOC
0.7%
0.4%
-0.2%
0.1%
2.6%
0.2%
4
' All are clear epoxy based coatings.
b All standard deviations are absolute.
c The maximum number of passes is the minimum number of passes to obtain Vto, to within 1%
(absolute).  The minimum number of passes for the method is 4.
                                     29

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TABLE 5-13  POLYESTER/STYRENE-BASED COATING BY EPA DRAFT METHOD
       Manufacturer
       Coating
       Date
       Number of Passes
       Exposure Index"
       Standard deviation
       ofL."
                        Lilly
       10168 Clear Polyester/Styrene-Based Coating
    3/20/92          5/13/92        6/08/92    7/12/92
  24248         16
0.22     0.44     0.22     0.44     0.89       1.95
13.8%   12.5%    15.2%   13.4%    3.5%       17.3%
0.1%    1.0%    1.3%    1.8%     6.9%       3.3%
L.V
Standard deviation
ofLj*
vtot
Standard deviation
ofVj>
0.4%
0.0%
17.0%
0.0%
0.3%
0.0%
15.4%
1.2%
0.6%
0.1%
17.8%
1.2%
0.6%
0.2%
16.6%
1.8%
8.8%
6.5%
14.7%
0.1%
0.9%
0.1%
19.6%
3.1%
       * Exposure Index = (number of passes) / [feed rate (ft/min)]
       b All standard deviations are absolute.
                                       30

-------
TABLE 5-14 THIOL/POLYENE-BASED COATINGS BY EPA DRAFT METHOD.
Manufacturer -
Coating*
Le
Standard deviation of L,b
Luv
Standard deviation of Lwb
Vtot
Standard deviation of Vwb
Max Passes

15 D
-1.2%
0.1%
0.6%
0.1%
-0.2%
0.8%
16
WR Grace
40376
0.1%
0.4%
0.9%
0.4%
2.2%
1.0%
4

CF-103B
-0.2%
0.9%
0.9%
0.1%
2.0%
1.0%
4
       1 All are clear thiol/polyene based coatings.

       b All standard deviations are absolute.

       e The maximum number of passes is the minimum number of passes to
       obtain V,,,, to within 1% (absolute). The minimum number of passes
       for the method is 4.
                                    31

-------

-------
                           REFERENCES
1)         "Method 24 - Determination  of  Volatile Matter Content,
          Water Content,  Density, Volume  Solids,  and Weight Solids
          of Surface Coatings", US Environmental Protection Agency,
          40 CFR 60, Appendix A.

2)         "ASTM D2369-87, Standard Test Method for Volatile Content
          of Coatings", American Society  of Testing and Materials,
          Philadelphia PA,  1987.

3)         "Revised Test Methods for Determining  VOC  of Radiation
          Curable Materials" ASTM proposed test  method for UV/EB
          curable   materials,    (unpublished    communications)
          October 1991.

4)         Radiation-Curable Coatings, Control Technology Center, US
          Environmental Protection Agency, Research Triangle Park,
        .  NC, EPA-600/2-91-035,  July 1991.
                               32

-------

-------
   APPENDIX A
LABORATORY DATA

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-------
                        APPENDIX B
                 INITIAL DRAFT ASTM METHOD
PROPOSED TEST METHODS FOR DETERMINING VOC OF RADIATION CURABLE
                         MATERIALS

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     PROPOSED TEST METHODS FOR DETERMINING VOC  OF  RADIATION CURABLE  MATERIALS



Method A:

     Scope: Only  materials containing less than 3X non-reactive solvent.

           1.  Weigh  a preconditioned Al panel or appropriate size Al foil to
              0.1  mg (W,).  Panels or  foil pieces  are preconditioned by
              drying for  30 minutes at 110* C and storing  in a
              desiccator.   Size  of Al substrate must allow a minimum of
              0.2 gm of  total  material to be applied at the supplier's
              recommended film thickness.  Standard 4" x 12" Al panels
              may be used when appropriate.  Use rubber gloves and/or
              tongs  to handle  samples.

           2.  Apply  a minimum  of 0.2 gm of material to the Al substrate
              and reweigh to 0.1 mg (Wj).   (See Note  1)

           3.  Cure the material  by exposure to UV or EB as prescribed by
              the supplier of  the material.

           4.  Allow  the  sample to cool 5 minutes at room temperature and
              reweigh to 0.1 mg  (W3).

           5.  Heat sample in a forced draft oven for 60 minutes at
              110+5' C.

           6.  Allow  sample to  cool to room temperature in a desiccator
              and reweigh to 0.1 mg (W4).

     Calculations:

                    X Processing  VOC s 100 [(Wj  - Wj)/(W2  -W,)]

                    X Potential VOC = 100  ((Wj - W4)/(Wj -W,)]

                    x Total VOC = X Processing VOC + X Potential  VOC

                    VOC (Wt/Vol basis: = (X VOC/100) x Density


Method B:
                                                 •
     •Scope:  All materials including those containing more than  3X
             non-reactive solvent.

           1. Weigh a preconditioned (see step  1 of Method A) Al dish with
               a minimum  diameter of 2 inches to 0.1 mg (W,).  Use rubber
               gloves and/or tongs to handle samples.

           2.  Add 3i1 ml of acetone (see  note 2) to the Al  dish  and,
               using a 1  ml syringe or eye dropper, weigh, by  difference,

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         to 0,1 mg (Wj) 0.3+0.1  gm of  material into the dish.  Swirl
         the disK to disperse the material in the  acetone and
         uniformly cover the bottom of the dish.

     3.  Dry the sample for 30 minutes at 50' C  (See  Note 3).
         Be sure that oven shelves are level.

     4.  Cure the material by exposure to UV or  EB as prescribed by
         the supplier of the material.

     5.  Allow sample to cool for 5 minutes at room temperature and
         reweigh (Wj).

     6.  Heat the sample in a forced draft oven  for 60 minutes at
         110+5* C.

     7.  Allow sample to cool to room temperature  in  a desiccator
         and reweigh (Wt).
Calculations:
              X Processing VOC = 100 [(Wj - (Wj  -W,

              X Potential VOC = 100 t(Wj - wt)/W2)

              X Total VOC = X Processing  VOC  •»•  X  Potential VOC

              VOC (Wt/Vol basis) = (X VOC/100)  x  Density
Note 1 -
Note 2


Note 3
               If the material to be tested contains any  non-reactive
               solvent, the elapsed time between  application and
               weighing should be no greater  than 30 seconds.   If  the
               material to be tested contains any reactive diluent
               with a vapor pressure at room  temperature  greater than
               1 mm Hg (e.g. styrene), the elapsed time between
               material application and weighing  must  be  no more than
               15 seconds.
           If the material is not compatible with acetone,
           a blend of acetone and THF may be substituted.
                                                               THF  or
               If  the  material contains  only  very  fast  solvents,  a
               lower temperature/shorter time may  be  substituted  if
               it  can  be demonstrated  that. the conditions are
               adequate to  remove at least 90x of  the original
               solvent in the composition.  Any remaining solvent
               will be removed during  the subsequent  cure and/or
               bake steps.

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                        APPENDIX C
                 INITIAL DRAFT EPA METHOD
DETERMINATION OF  VOLATILE ORGANIC CONTENT FOR ULTRAVIOLET
                 RADIATION-CURED COATINGS

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    DETERMINATION OF VOLATILE ORGANIC CONTENT FOR
           ULTRAVIOLET RADIATION-CURED COATINGS
L   Applicability and Principle

    1.1 Applicability.  This method applies to the determination of the volatile
organic content of ultraviolet radiation-cured coatings (UV-cured coatings).
This method has been tested with commercial UV-cured coating formulations,
including acrylic-based  formulations,  cationic epoxies, polyester/styrene, and
thiol-poiyene based coatings.

    1.2 Principle.  UV-cured coatings are a class of coatings that contain
unreacted monomers that are polymerized by exposure to ultraviolet light.  This
method measures the weight loss from UV-cured coatings in each of three
steps:

    •   sitting at room temperature to simulate product handling,
    •   after UV exposure to produce a cured coating, and
    •   after 1 hour in a 110°C oven to simulate the final life of the product.

The procedure includes a test for cure, which involves comparison of total
weight loss of a sample cured at multiple exposures.
2.  Precision

    Based on studies performed on laboratory samples having 0 to 11% total
volatiles (Vto,, see Section 6.5), the intralaboratory absolute standard deviation
for total volatiles using this method averaged 0.9 percent.
3.  Apparatus

    3.1 UV-Exposure Apparatus.  A conveyor-fed ultraviolet curing apparatus.
The ultraviolet light shall be provided by one or more medium-pressure
mercury vapor lamps with quartz housings, capable of providing light with a
wavelength of between 200 and 400 nm. The lamp and conveyor system must
be capable of providing sufficient exposure for the materials being tested (see
Section 4). Other apparatus may be used if approved by the Administrator.

    3.2   Oven. A forced-draft oven capable of maintaining a temperature of
110 ± 2°C for 1 hour.

-------
    3.3 Thermometer.  A thermometer capable of measuring oven temperature:
to ± 1°C.

    3.4 Balance.  A balance capable of weighing to ± 0.0001 g.

    3.5 Sample Dishes. Circular flat-bottomed aluminum foil weighing
dishes, approximately 58 mm in diameter by 18 mm high.

    3.6 Desiccator.  An airtight container, with desiccant, large enough to
contain samples dishes.

    3.7 Desiccant. Calcium sulfate (e.g., indicating Drierite") or equivalent
desiccant.

    3.8 Disposable Pipettes. Disposable 5-ml polyethylene transfer pipettes.

    3.9 Acetone.  ACS reagent grade  or equivalent.

    NOTE: If acetone  is not an adequate solvent for the material being tested,
another solvent with a sufficiently low  boiling point (< 60°Q may be used.
Solvent must be tested to determine if  it evaporates completely from the
coating at room temperature; i.e., the evaporative loss (LJ should be greater
than or equal to zero (see Section 6.2).


4.  Procedure

    NOTE:. All items that are weighed (e.g., sample dish, pipettes) must be
handled with gloves or  sample tongs.

4.1 Initial Analysis

     4.1.1  Condition the aluminum sample dishes by heating them in a
forced-draft oven at 110 ± 2°C for at  least 1 hour.  Remove the dishes and
allow them to cool in a desiccator.  Store the conditioned dishes in a
desiccator.

     4.1.2  Weigh  an aluminum dish to ± 0.0001 g and record this weight as
Wj.  Mix the coating thoroughly and fill a disposable pipette with enough
coating to deliver  0.2 ± 0.1 g of coating.  Weigh the  coating-filled pipette to
± 0.0001 g and record this weight as W2.  Place 3 ± 1 mL qf acetone in the
aluminum dish and carefully add the coating into the dish. Gently swirl the
 " Mention of trade names or specific products does not constitute endorsement by
 the Environmental Protection Agency.

-------
dish to disperse the coating, talcing care not to spill any material. Weigh the
pipette after the sample has been dispensed to ± 0.0001 g and record this
weight as Wv
    NOTE:  It may be difficult to accurately dispense viscous samples from a
pipette.  In order to achieve more uniform amounts (i.e. ±0.1 g), it may be
helpful to add the sample to the dish while on a balance.  The acetone may
then be added to the sample and the dish swirled to disperse the sample
uniformly. Because of the possibility that volatiles might be lost during
weighing, the sample weight W7 should be calculated as described in
Section 6.2.  An alternative procedure for viscous samples would be to use a
syringe in place of the disposable Pipette.

    4.1.3 Place the sample dish on a level surface at room temperature in a
laboratory fume hood for 30 minutes to allow the acetone to evaporate, then
weigh the sample dish to ± 0.0001  g and record this weight as W4.

    4.1.4 Cure the coating by exposing it to UV light at twice the exposure
specified by  the manufacturer (i.e., double the number of passes through the
exposure apparatus  at the manufacturer's suggested rate and intensity).  Allow
the sample to cool to room temperature (approximately 30 seconds) between
passes.  After all the passes have been completed weigh the sample to
± 0.0001 g and record this weight as Ws.

    4.1.5 After UV exposure and weighing, place the sample dish in a
110 ± 2°C oven for 1 hour.  Remove  the sample dish and allow it to cool to
room temperature in a desiccator. Weigh the sample  dish to ± 0.0001 g and
record this weight as W6, then calculate Vw (percent)  as in Section 6.5.

    4.1.6_ Analyze  samples in triplicate and calculate an average total organic
content,  Vw (percent) as in Section 6.6.

4.2 Subsequent Analysis

    4.2.1 Using fresh samples of the material from the same lot as the sample
in Section 4.1, repeat Sections 4.1 using four times the manufacturer's
recommended exposure time (i.e., four times the number of passes at the
manufacturer's suggested curing conditions). Calculate Vm  as  in Section 6.5.

    4.2.2 ^Analyze  samples in triplicate and calculate an average total organic
content,   V,,,, (percent)  as in Section 6.6.

    4.3  If the average total volatile organic content,  V,,,, (percent) calculated in
Section 4.1 does not agree to ± 1 percent  (absolute) with the one calculated in
Section 4.2, repeat Section 4.2 doubling the last exposure. Compare to the

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prior exposure'results until the average total organic content, VM (percent) of -
two consecutive exposures tested at the same feed rate and intensity agree to
± 1 percent (absolute).

    NOTE:  If the criterion has not been met by the second time that
Section 4.2 is repeated, the tester may want to  consider changing curing
conditions (i.e.,  feed rate and intensity) and repeat Sections 4.1 through 4.3
beginning at twice the manufacturer's exposure with the modified curing
conditions.

    4.4  Perform analyses in triplicate for each coating until the criterion in
Section 4.3 is met. Record the V— values used to meet the criteria in
Section 4.3 with the corresponding curing conditions and exposure. Report the
higher of the two  values obtained as  VM from the sample being tested.

    NOTE:  Underexposed UV-cured coatings may show excessively high
levels of total volatile organic content, Vw (Section 6.5). This may be
corrected by adjusting the exposure level as described in Section 4.2.
Overexposed coatings may show charring, discoloration, and bubbling. This is
often due to thermal overexposure  rather than UV overexposure.  To reduce
thermal effects, lower intensity or increase the  feed rate and increase the
number of passes  through the apparatus.  Allow the samples to cool to room
temperature  (approximately 30 seconds) between passes.

5.  Calibration and Audits

    5.1  Analytical Balance.  Calibrate against standard weights.

    52 Thermometer.  Calibrate against a National Institute of Standards and
Technology (NIST)-traceable thermometer.

    5.4  Audit Procedure. Analyze the performance audit sample, if available.
The same analyst, analytical reagents, and analytical system shall be used both
for compliance samples and the EPA audit samples. If this condition is met,
auditing of subsequent compliance analyses for the same enforcement agency
within 30 days is  not required.  An audit sample set may not be used  to
validate different  sets of compliance samples under the jurisdiction  of different
enforcement agencies, unless prior arrangements  are made with both
enforcement agencies.

     5.5  Audit Samples. Audit samples will be supplied only to enforcement
agencies for compliance tests. The availability of audit samples may be
obtained by writing:  Source test Audit Coordinator (MD-778), Quality
Assurance Division, Atmospheric Research and Exposure Assessment
Laboratory, U.S.  Environmental Protection Agency,  Research Triangle Park,
 NC 27711  or by calling the Source Test Audit Coordinator (STAC) at

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(919) 541-7834. The request for the audit sample must be made at least
30 days prior to {he scheduled compliance sample analysis.

    5.6 Audit Results.  Calculate the audit  sample concentration according to
the calculation procedure described in the audit instructions included with the
audit sample. Fill in the audit sample concentration and the analyst's name on
the audit response form  included with the audit instructions. Send one copy to
the EPA Regional Office or the appropriate  enforcement agency and a second
copy to the STAC The EPA Regional  Office or the appropriate enforcement
agency will report the results of the audit to the laboratory being audited.
Include this response with the results of the  compliance samples in relevant
reports to the EPA Regional  Office or the appropriate enforcement agency.
6. Calculations

    6.1 Nomenclature.


   L,  « Evaporative loss, percent
  L^  » UV loss, percent.
  VM  • Total volatile organic content,
         Total volatile organic content of first sample, percent
   g.  • Total volatile organic content, of g^rH sample, percent
   f    - Total volatile organic content of third sample, percent
   UXj
  Vgg  • Average total volatile organic 
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    6.3  Evaporative Loss. The evaporative loss (LJ is calculated as:
                           (W. + W. - WJ
                      L  » V   l     7     y x 100
                                  W7
    6.4 UV Processing Loss. The UV processing loss (LO is calculated as
    6.5 Total Volatiles. The total volatile organic content is calculated as:

                     „     W  * w7 - w«)
                                   W7
                                              x 100
    6.6 Average Total Volatiles.  The average of the total volatiles Vw is
calculated for triplicate samples as:

                               V   + V   + V
                               T      Y      Y
Report the average of the triplicate analyses rounded to ±0.1 percent.
7,  Bibliography

     1.  U.S. Environmental Protection Agency, Method 24 - Determination of
Volatile Matter Content. Water Content. Density. Volume Solids, and Weight
Solids of Surface Coatings.  40 CFR 60, Appendix A.

     2.  American Society of Testing and Materials, ASTM D2369-87. Standard
Test Method For Volatile Content of Coatings. Philadelphia, PA, 1987.

     3.  American Society for Testing and Materials. Revised Test Methods for
Determining VOC of Radiation Curable Materials. ASTM proposed test method
for UV/EB curable materials (unpublished communications), October 1991.

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                APPENDIX 0
RESPONSES TO COMMENTS ON DRAFT EPA METHOD

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                                    APPENDIX D

             RESPONSES TO COMMENTS ON EPA DRAFT METHOD


Commenter: 1

       1.1  Comment:  The method may have difficulties with skin formation.

       Response:  The  current procedure is acceptable (even if some coatings have L. < 0)
for a regulation based on total voiatiles (i.e., V,Jt  since measurement for VM involves
heating at 110  °C, which will drive off any remaining solvent.
       Skin formation may affect Le and LW. since they have no heating step to drive off
solvent. If future regulations are to use LUV, then the method may  require  modification. This
could be done by allowing the solvent to evaporate at a higher temperature, such as the 50 °C
oven proposed by ASTM in revisions to D2369.   Unfortunately, the use of a higher
temperature to evaporate the solvent would increase the risk of evaporating reactive
monomers that would normally be incorporated in  the coating. This could lead to excessive
values of volatile loss as measured by the method (i.e., as compared to actual usage).  This
could be a problem for polyester/styrene based coatings due to the  volatility of styrene.
Laboratory tests with an acrylic based coating showed no difference between solvent
evaporation at 50 °C and at room temperature. Any method to measure the processing loss
will necessarily be a  compromise between driving  off the dispersing agent  and driving off
reactive monomers.
Commenter:  2

       2.1 Comment:  This method only measures the VOC content of a completely cured
coating.  It does not address facility emissions due to poor cure or overspray.

       Response: This comment was noted by several reviewers. This method measures
properties of a coating, rather than properties of a coating process or facility. A coating test
method should be capable of giving results that are identical (i.e., within a reproducibility
error) when a sample of coating is tested by different laboratories.  For a reproducible test, it
is necessary that the coating be fully cured and that no overspray be considered.
Commenter:  3

       3.1 Comment: Does the method work with materials with more than 11% VOC?

       Response:  It is felt that this method should work as well, if not better, with higher


                                          D 1

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VOC materials, since they will  form thinner films that will be more easily cured.  Additional
testing performed after the Draft Method was circulated showed good precision (i.e., less than
1% absolute statdard deviation within  triplicate samples) for a coating with 30% total
volatiles.
       3.2 Comment: The description of exposure apparatus does not include provisions for
use of inert atmospheres during exposure.

       Response:  In general, inert atmospheres are used only for electron-beam cured
coatings, which are not  specifically addressed in this method.
       3.3 Comment:  Why should the evaporative loss (LJ be greater than or equal to zero?
What would happen if it isn't?

       Response: For measurement of total volatile  loss CO, it makes little difference
whether the L. is positive, i.e., whether all the solvent has evaporated before curing, since any
remaining solvent will be evaporated either in the curing step or upon heating. (This assumes
that the solvent does not interfere with curing.)  The UV exposure loss (Luv) would be
affected (i.e., would be lower) if any solvent that remains after curing.
       3.4  Comment: The note under Section 4.1.2 does not clearly explain the purpose for
weighing the samples on a balance.  In particular, the word accurately is poorly chosen.

       Response: The word accurately should be dropped from the first sentence of the note
and the note revised for clarity.  The revised note would read as follows:

              NOTE:  It may be difficult to dispense viscous samples from a pipette.   To
       achieve uniform sample weights (i.e., ± 0.1 g), it may be helpful to place the sample
       dish on a balance and add the required amount of sample. The acetone (or other
       solvent) would then be added to the  sample and the dish swiried  to disperse the
       sample uniformly.  Because of the possibility that volatiles might be lost during
       weighing, the sample weight W? should still be calculated as described in Section 6.2.
       An alternate procedure for viscous samples would be to use a syringe in place of the
       disposable pipette.
        3.5  Comment:  The exposure is referred to in several different ways.  A standard
 wording should be used to reduce confusion.

        Response: This subject was also discussed by others who had seen the Draft Method.
 Confusion can easily arise when the word rate is used to indicate the total exposure, the lamp


                                           0  2

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intensity,  and the conveyor belt feed rate (which is inverse with exposure).  To reduce  ~~
confusion, the method should be modified so that the word rate is used only for the conveyor
belt feed rate. The phrase exposure should be used to indicate the total exposure and the
"manufacturer's suggested curing conditions" in Section 4.2.1 and the "manufacturer's
suggested rate and intensity" in Section 4.1.5 should be replaced with "manufacturer's
suggested lamp intensity and conveyor feed rate".
       3.6 Comment:  Why is the procedure done twice at two different exposures?

       Response: Due to different lamp and reflector designs, the actual emissions obtained
at a specified lamp intensity (given in watts  of input power per length of lamp) may vary
widely between exposure facilities.  Experimental work has shown that coatings may show
high total volatile emissions (V^) if adequate cure is not obtained. To obtain values of total
emissions (V^) that could be consistent between laboratories (note that interlaboratory testing
of the Method has not yet been performed) it is necessary to provide at test for adequate cure.
 Most commercial UV-cured coatings are somewhat resistant to ovcrexposure.  A simple test
for adequate cure is to repeat the method at double the original exposure.  If the results at
double the exposure agree with the results at the original exposure to within 1%, absolute,
then the cure is adequate.
       3.7 Comment:  Why is two passes at the manufacturer's suggested lamp intensity and
conveyor feed rate used for the first attempt?

       Response:  In laboratory studies, the manufacturer's suggested lamp intensities and
conveyor feed rates did not always provide adequate curing.  For this reason, the test method
is done at least two exposures • one at twice the manufacturer's suggested lamp intensity and
feed rate and again at four times the manufacturers suggested lamp intensity and feed rate.
Agreement at these two exposures indicates proper cure.
       3.8 Comment:  The requirements for auditing the method are unclear.

       Response:  At the current time, no audit materials for this method have been
developed. The need for and frequency of audits has not been determined.  Sections 5.4 and
5.5 were included in the Draft Method to permit auditing to be performed in the future (i.e.,
after development of suitable audit materials) without revising the Draft Method in the   '
Federal Register.
       3.9 Comment:  The UV processing loss (L^, equation 6.4) is not used.  It should be
removed from the method.
                                          D  3

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       Response: At the current time, it has not been decided whether future regulations
should consider the processing losses. If future regulations are to use only the total volatile
loss (Vyy)  then  ail  reference to L^y and Ws should be removed.
       3.10 Comment:  The method measures the volatiles per unit mass of coating.  The
value should be multiplied by the density of the coating to get the volatiles per unit volume
of coating, for example, pounds per gallon of coating.

       Response: The current method is for weight percent volatiles.  The  conversion to
mass of volatiles per unit volume could be easily incorporated, if needed.
Commenter 4

       4.1  Comment:  Use of the term "Volatile Organic Content" may be misleading since
the method actually measures total volatiles.

       Response:  The compounds tested did not have water present and, for these
compounds, the total volatiles are the Volatile Organic Content.  The method should be
revised to more clearly state that total volatiles (as opposed to volatile organics) are
measured.  We are not aware of any commercially available water-based UV curable coatings.
If it appears likely that such coatings are  to be available commercially, then the draft method
should be modified to include a correction for water content (as in EPA Method 24).
Commenter 5

       5.1 Comment: Repeatability and reproducability are not stated for the method.

       Response:  Estimation of reproducability would require an interlaboratory study of the
method, which has not been performed.
       5.2 Comment: Use of a transfer pipette may permit low-viscosity samples to drip out
of the pipette.  Disposable syringes should be used.

       Response:  The coatings tested during the development of this method did  not drip out
of the pipette.  If low-viscosity causes problems, then disposable syringes could be used.
       53 Comment: The disposable gloves should be free of talc.

       Response:  The method should be revised to specify talc-free gloves.


                                          D  4

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       5.4  Comment:  Weighing on a moving pan (see note in Section 4.1.2) presents a
moving target due to evaporation. Results will give lower VOC.

       Response: The weighing of the sample in the pan (note on Section 4.1.2) is only to
achieve a more uniform sample size (i.e. ±0.1 g).  This sample weight is not used in the VOC
calculations.  The calculated sample weight is the weight of the pipette before and after
dispensing the sample.


       5.5  Comment:  Triplicate samples add little to method precision (compared to
duplicates), but require  extra effort.  Duplicates should be used instead of triplicates.

       Response: The uncertainty associated with the sample mean should decrease with the
square root of the number of samples used to calculate the mean.  Thus going from 2
samples to 3 samples should decrease the uncertainty of the mean by:
                                   1 - ,/±  -  18 %
Commenter 6

       6.1  Comment:  Method will not accommodate materials containing solvent, pigment,
or styrene.

       Response: Solvent containing materials should work well with the EPA draft method,
as it does not weigh the sample on an open balance.  Pigmented materials may be a problem
due to excessive film thickness. The use of larger weighing dishes (for more surface area and
thus thinner films) may be useful if problems are seen with* heavily pigmented coatings.
Styrene is a problem that is likely to exist for all volatile methods.
                                          D 5

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                        APPENDIX E
                REVISED DRAFT ASTM METHOD
PROPOSED TEST METHODS FOR DETERMINING VOC OF RADIATION CURABLE
                        MATERIALS

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This document is  part of the                                        Draft No. 4
ASTM standards process  and is  for                              August  6, 1992
ASTM committee use only.  It shall
not be reproduced or circulated
or quoted, in whole or in part,
outside of ASTM committee
activities except with the
approval  of the chairman of the
committee having  jurisdiction or
the President of the Society.
                           ASTM Designation: D	

 Standard Test Methods for

 VOLATILE CONTENT OF RADIATION  CURABLE MATERIALS

 1.   -  Scope

       1§1          These test methods describe procedures for the  determination

 of weight percent volatile content  of coatings, inks, and adhesives designed to

 be cured by exposure to ultraviolet light or to a  beam of accelerated electrons.

       1,2          Test method A is applicable to radiation curable materials which

 are essentially 100X reactive but may contain traces  (no more than 3X) of volatile

 materials as impurities or introduced by the inclusion of various additives.

       1.3         Te8t method B is applicable  to  all radiation curable materials

 but must  be used for materials  which  contain  volatile solvents  intentionally

 introduced to control  application viscosity and which are  intended to be removed

 from the  material prior to cure.

        1,4          These test methods may not be  applicable to radiation  curable

  materials  wherein the volatile solvent  is water,  and other procedures may be

  substituted by mutual consent of the producer and user.

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      1.5          This standard may involve hazardous materials, operations, and



Equipment.  This standard does  nor purport tc address all of the safety problems



associated with its use.  It is the responsibility of  the user of this  practice to



establish appropriate safety and health practices and  determine the applicability



of regulatory  limitations prior  to use.  A specific hazard  statement is given  in



Note 8.



2.    Referenced Documents



      2.1          ASTM Standards



      D 2369      Test  Method  for  Volatile Content of Coatings1



      E 145       Specification for Gravity  Convection and Forced Ventilation



                    Ovens



      E 177       Practice for  Use of  the terms  Precision and Bias in ASTM



                    Methods



        E 691      Practice for Conducting an Intel-laboratory Study to  Determine



                    the  Precision of a  Test  Method*



 3.     Terminology



       3.1         Definitions



       3.1.1        pure - the condition of a coating after conversion to the final



 state of cure as measured by tests generally related to end  use performance and



 mutually agreeable to supplier and purchaser.



       3.1.2        yitraviolet (UV) Curing  - conversion of a coating from its



 application  state  to its final  use state  by means  of a mechanism  initiated by



 ultraviolet radiation generated by  equipment designed for  that purpose.



       3.1.3        Electron Beam (EB)  Curing - conversion  of a coating from ita



 application  state to its final use state by means of a mechanism initiated by



 electron beam radiation generated  by equipment designed  for  that purpose.

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       3.1.4          Processing Volatiles -  loss  in  specimen  weight under test



conditions which are  designed  to simulate actual  industrial  cure  processing



conditions.



       3.1.5        Potential Volatiles - loss in specimen weight upon  heating  at



110* C  for  60 minutes. This  is an estimation  of volatile loss which  may occur



during  aging or under extreme storage conditions.   Potential Volatiles may also



be  referred  to as  residual volatiles.



       3.1.6        Total Volatiles - sum of the Processing  Volatiles  and the



Potential  Volatiles.



4.    Summary of  Test Method



      4.1          A designated quantity of material is weighed  before and  after



a cure step  which simulates  normal industrial  processing.  The  test specimen  is



weighed again after heating  at 110±5*C for 60 minutes.  The  percent  volatile  is



calculated from the  losses in weight.



5.    Significance and  Use



      5.1          These  test  methods  are   the  procedures   of  choice  for



determining  volatile content of materials  designed to  be cured by  exposure to



ultraviolet light or electron  beam  irradiation.   These types of "materials contain



liquid reactants  which  react to become part of the film during cure, but, which



under the test conditions of Test  Method  D 2369, will be erroneously measured



as  volatiles.   The conditions  of these test methods are similar to Test Method



D 2369 with the inclusion of a step to  cure   the material prior to  weight loss



determination.   Volatile content is determined  as  two  separate  components  -



processing volatiles and potential volatiles. Processing volatiles is a measure of



volatile loss during  the actual cure process.  Potential  volatiles  is a measure of



volatile loss  which might occur during aging or under extreme storage conditions.

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These volatile content measurements are useful  to the producer and  user of a
material and to environmental interests for determining emissions.
6.    Interferences
      6,1          The degree to which the results of these procedures accurately
measure  the volatiles  emitted during actual use is absolutely dependent upon
proper cure during the test procedure.   Although overcure will have little or no
effect upon measured  volatiles, undercure  may lead to erroneously high values.
Since various  pieces  of cure  equipment may vary  widely in efficiency, it is
essential  that dialogue between material manufacturer and testing lab establish
a cure schedule  appropriate both  to  the material to  be tested and to the cure
equipment to be  used in the procedure.  See Note 2.
                               TEST METHOD A
7.    Scope
      T.I         This method is  applicable to  radiation  curable materials with
 solvent content less than or equal to 3X.
 8.     Apparatus
       8.1        Aluminum Substrate,  standard test panels (102mm x 305mm) or
 heavy gauge (0.05 mm min.) foil.   Test panels are most convenient and  may  be
 cut into  smaller  pieces for  ease of weighing.   Precondition the substrate for 30
 minutes at 11045*C and store in a desiccator prior to use.
       8.2        Forced Draft Oven. Type IIA or Type IIB as specified in
 Specification E 145.
        8.3        Ultraviolet Light or  Electron Beam Curing Equipment  - there
 are several commercial suppliers of laboratory scale  equipment which simulates
  industrial curing processes. A list of such suppliers may obtained by contacting
  RadTech International N.A., 60 Revere Drive,  Suite 500, Northbrook, IL 60062.

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9.     Procedure  •


      9.1         Mix  the  sample, if necessary, to  ensure  uniformity.   Hand


stirring  is recommended  to avoid  the entrapment of air bubbles.


      9.2         Weigh  the preconditioned Al substrate (8.1)  to 0.1 rag (A).  The


size of the Al substrate must allow a  minimum of 0.2 gm of material to be applied


at the supplier's recommended  film thickness.  Use rubber  gloves and/or tongs


to handle samples.






      9.3         Apply  a minimum of 0.2 gm of test specimen to the Al substrate


and reweigh to 0.1  mg (B).  Prepare a total of three test specimens


      Note 1 - The  elapsed time between application and weighing should be no


greater  than 30  seconds.   If  the sample  to be tested contains any reactive


diluent with a vapor pressure at room temperature  greater than 1.0 mm Hg (e.g.


styrene), the elapsed time between specimen application and  weighing must be no


greater  than 15  seconds.


      9.4         Cure the test specimen by exposure to UV or EB as prescribed


by the supplier  of  the material.               }
                                              i

      Note  2 - If there  is 'any doubt as to  the adequacy  of the exposure for


affecting proper cure (6.1), an  additional sample  can be  tested utilizing  SOX


additional exposure  and  the volatile  content  results compared.   If the original

                                               i

exposure was adequate,  there should be  no difference in the  results  within the
                                               i

 precision of the test method.  If the results are different, the supplier of the


 material must be contacted and a revised cure schedule established.


      ^9.5          Allow  the test specimen to cool 15 minutes at room temperature


 and reweigh to  0.1 mg (C).

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      9.6          Heat the test specimen in a forced draft oven  (8.2) for  60



minutes  at  110+5'C.



       Note 3 - Materials which can react with atmospheric moisture during  post



cure, i.e. UV cationic curable epoxy materials, may exhibit a weight gain during



step 9.6.  If this ocurs, the  sample should be  retested and allowed to post cure



at room  temperature  for 48  hours after step  9.5,  and then reweighed  prior  to



step 9.6.  The weight after  post cure should  then be used as  weight C in the



calculation of X  Potential  Volatiles  in  step 10.1.



      9.7          Allow the  test   specimen  to cool  to room temperature  in  a



desiccator and reweigh to 0.1  mg   (D).



10.   Calculations



      10.1         Calculate the weight  percent volatiles  as follows:



                   X Processing Volatiles =  100 [(B - C)/(B - A)]



                   X Potential Volatiles - 100 t(C - D)/(B - A)]



                   X Total volatiles = X Processing Volatiles +  X Potential Volatiles



where:



A = weight of Al substrate



B = weight of Al substrate plus test  specimen



C = weight of Al substrate plus test  specimen after  cure



D = weight of Al substrate plus cured test specimen after heating



11.          Precision and Bias



             11.1        Interlaboratory Test Prograq - An interlaboratory study*



of volatile content of radiation cured  materials (Test Method A) was conducted in



accordance with  Practice E  691  in nine laboratories with  three materials,  with



each laboratory obtaining three test  results for each material.
                                        6

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             11%2         Test Result - The precision information given below for


volatile content in weight percent is for the comparison of two test results,  each


of which is the average  of three test determinations


             11.3          Precision


Processing Volatiles


     95X repeatability  limit  (within laboratory)         0.9X


     95X reproducibility  limit (between laboratories)    1.6X


Potential Volatiles


     95X repeatability  limit  (within laboratory)         2.2X


     95X reproducibility  limit (between laboratories)   4.2X


Total Volatiles


     95 X repeatibility limit (within  laboratory)        2.3X


     95X reproducibility  limit (between laboratories)   3.9X


The terms  repeatability limit  and reproducibility  limit are  used as  specified in


Practice  E  177. The respective  standard deviations among test results may be


obtained by  dividing the above  limit values by 2.8.  The form of this precision


statement is in accordance with  Practice E 177, section 31.1.


             11.4         Bias  -  Since  there is  no accepted reference  material,


method, or laboratory suitable for determining the bias for the procedure in  this


test method  for measuring the volatile content of radiation  cured materials, no


statement of bias  is  being made.


                                TEST METHOD B
    •

12.          Scope


             12.1         This  method  is  applicable  to  all   radiation curable


materials which will cure properly  at the  designated specimen weight,  which


corresponds to a film thickness of 50 to 75  microns depending  upon  solvent

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content. Method B is the method'of choice for all radiation curable materials with
                 »


solvent content greater than 3X.


             12.2         This method  is not applicable  to materials containing



styrene  due to its volatility at 50 *C.



13.         Apparatus


            13.1        Aluminum Foil Dish. 58 mm in  diameter  by 18 mm height



with a  smooth  (planar) bottom surface.   Precondition  the dishes  for 30  minutes



in an oven at  110±5*C and store  in a desiccator prior to use.



            13.2        Forced Draft Oven. Type IIA or Type IIB  as  specified in



Specification E 145.


            Note  4 -  The shelves of the Oven must be level.



            13.3        Syringe.  1  ml,  capable  of  properly  dispensing  the



material under test at sufficient rate that the specimen can  be dissolved in  the



solvent.  Disposable  syringes  are  recommended.


             13.4        Ultraviolet Light or Electron Beam Curing Equipment -



there  are  several- commercial  suppliers  of  laboratory  scale  equipment which



simulates industrial curing processes. A list of such suppliers  may be obtained



by contacting  RadTech International N.A., 60 Revere Drive, Suite 500, Northbrook,



IL 60062.


14.          Reagents


             14.1         Purity of Reagents - Reagent grade  chemicals shall be


used in all tests.  Unless otherwise  indicated, it is intended that all reagents



shall conform  the specifications of the  Committee  on Analytical  Reagents of  the



American Chemical Society, where such specifications are available . Other grades



may be used,  provided it is first  ascertained that the reagent is  of  sufficiently



high purity to permit its use without lessening the accuracy of the determination.'




                                       8

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15.       "   Procedure

            15.1         Mix the sample, if necessary, to ensure uniformity.  Hand

stirring  is recommended to avoid the entrapment of air bubbles.



            15.2         Weigh a preconditioned Al dish (13.1) to 0.1 mg (A).
                                                                             •
Use rubber gloves and/or tongs to handle sample dishes.

            15.3         Using  the syringe   (13.3) weigh  to 0.1  mg  (B),  by

difference, 0.310.1 gm of test specimen into the foil dish to which has been added

3±1 ml of acetone.  Add the material  dropwise, swirling the dish to disperse  it

completely in the acetone.  If the material forms a lump that cannot be dispersed,

discard  the test specimen  and  prepare a new one.   Prepare a total  of three

samples.

            Note 5 - Be  sure to wipe the outer surface of the syringe clean after

obtaining the test specimen.  Pull the  syringe plunger up 1/4  of  an inch  to pull

the material away  from  the neck of the syringe.  Cap and weigh the syringe.

After dispensing the  test specimen, do not wipe the tip of the syringe.  Remove

the material from  the neck  of the  syringe  by pulling up  the  plunger.  Cap and

reweigh the syringe.  Note that sample weight (B)  = initial weight syringe - final

weight syringe.

            Note 6 - Use disposable rubber gloves or polyethylene to handle the

syringe.

            Note   7  -   If  the   material  is  not  compatible   with  acetone,

tetrahydrofuran (THF)  or a blend  of  acetone  and THF may  be substituted.

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            15.4         Heat the samples in the forced draft oven (13.2) for 30
                 *

minutes at 50±2*C.

            Note 8 - This step is critical since a large amount of solvent present


in the sample during cure will interfere with the cure process and an inadequate


degree of cure may result, which could produce erroneous volatile results (6.1).


If the material contains only very fast solvents, a lower temperature/shorter time
                                                                      •
may b« substituted if it can be  demonstrated that the conditions are  adequate


to remove at least 90% of the original solvent in the composition.   Any remaining


solvent will be removed during  the subsequent cure and  heating  st.eps.  In the

case  of  samples  which contain  volatile solvents  for  control  of  application

viscosityi this step also simulates  the industrial processing stage necessary to


 remove the solvent prior cure.

             15.5         Cure the  test specimen by  exposure to UV or EB  as


 prescribed by the supplier of the material.   See Note 2.

             15.6         Allow  test  specimen to cool for  5 minutes  at  room


 temperature and reweigh (C).

             15.7         Heat the test specimen in  the forced draft  oven (13.2)


 for 60 minutes at HOtS'C.

             Note  9 -  Precaution:   In addition  to  other precautions,  provide


 adequate ventilation, consistent with accepted laboratory  practice,  to  prevent


 solvent vapors from accumulating to a dangerous level.

             15.8        Allow test specimen  to cool to  room temperature in a


 desiccator and reweigh (D).
                                       10

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16.          Calculations



            16.1        Calculate the weight percent volatiles  as follows:



                        % Processing Volatiles  s  100 [B - (C - A)]/B



                        X Potential volatiles s  100 ((C  - DJ/BJ




                        % Total  Volatiles  =  X Processing Volatiles +




                                               X  Potential Volatiles








where:



A =  weight of Al dish



B =  weight of test specimen




C =  weight of Al dish plus  test  specimen after  initial heating and* cure



D =  weight of Al dish plus  cured test specimen after final heating



17.          Precision and Bias




                        17.1         Interlaboratory   Test   Program   -   An



interlaboratory  study  of volatile  content  of  radiation cured  materials  (Test




Method B)  was conducted in accordance with Practice E 691 in eleven laboratories



with three materials, with each laboratory obtaining three test results for  each



material.



             17.2        Test Result - The precision information given below for



volatile content in  weight percent is for the comparison of two test results,  each



of which is the average of three test determinations.



             17.3         Precision



Processing Volatiles



      95X repeatability  limit (within  laboratory)          2.0X



      95X reproducibility  limit (between laboratories)    3.4X
                                       11

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Potential Volatiles



     95X repeatability limit  (within  laboratory)          1.1X



     95X reproducibility  limit (between  laboratories)    4.7X



Total Volatiles



     95X repeatability limit (within laboratory)         2.OX



     95X reproducibility  limit (between  laboratories)    5.IX



The terms repeatability limit  and reproducibility limit are used as  specified in



Practice E 177.  The respective  standard deviations among test results may  be



obtained by  dividing the above  limit values  by 2.8.  The form of this precision



statement is in accordance with  Practice E  177, section 31.1.



             17.4         Bias  -  Since there  is  no accepted reference  material,



method, or  laboratory  for determining  the  bias for the procedure in this test



method for  measuring volatile content of radiation cured materials, no statement



on bias is being made.



18          Key Words



             18.1              Volatile   content;   radiation  curing;   ultraviolet



curing; electron beam curing; radiation curable material.
                                       12

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                                 FOOTNOTES








lThis test method is under the jurisdiction of ASTM Committee D-l on Paint and




Related  Coatings and Materials and is the direct responsibility of  Subcommittee



D01.55 on Factory Applied Coatings of Preformed Products.



Current edition approved	.  Published	.



 Annual  Book of  ASTM Standards. Vol. 06.01



 Annual  Book of  ASTM Standards. Vol. 10.01



^Annual  Book of  ASTM Standards. Vol. 06.03




 "Reagent Chemicals, American Chemical Society Specifications," Am. Chemical Soc.,




Washington, DC.   For  suggestions  on the testing of reagents not listed by the



American Chemical  Society, see "Reagent Chemicals and  Standards,"  by Joseph



Rosin, D. Van Nostrand., Inc.,  New York, and the "United States  Pharmacopeia."



 Supporting data are available  from ASTM headquarters.   Request RR: DOl-xxxx.
                                     13

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                        APPENDIX F
                 REVISED DRAFT EPA METHOD
DETERMINATION OF  VOLATILE ORGANIC CONTENT FOR ULTRAVIOLET
                 RADIATION-CURED COATINGS

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            REVISED .   . DRAFT
DETERMINATION OF VOLATILE ORGANIC CONTENT FOR
    ULTRAVIOLET RADIATION-CURED COATINGS
           EPA  Project No.  6SD10009
            Work Assignment 1-132
                February 1993
               Project Officer

              Lourdes  L.  Morales
         Emissions  Measurement  Branch
 Office  of Air Quality Planning and  Standards
      Research Triangle  Park,  NC  27711

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     DETERMINATION OP VOLATILE ORGANIC CONTENT FOR
         ULTRAVIOLET  RADIATION-CURED  COATINGS
1. Applicability and Principle

   1.1  Applicability.  This method applies to the
determination of the volatile organic content of
ultraviolet radiation-cured coatings (UV-cured
coatings).    This method has been tested with
commercial UV-cured coating formulations, including
acrylic-based formulations,  cationic epoxies, and
thiol-polyene based coatings. This method  has been
tested on UV-cured coatings with total volatiles
between 0 and 30 percent, as determined by the method.
The method is not applicable to coatings containing
styrene.

   1.2  Principle.  UV-cured coatings are a class of
coatings that contain unreacted monomers that are "
polymerized by exposure to ultraviolet light.  This
method measures the weight loss from UV-cured coatings
in each of three steps:

   •  sitting at room temperature to simulate product
      handling,

   •  after UV exposure to produce a cured coating,  and

   •  after 1 hour in a 110°C oven to simulate the
      final life of the product.

The procedure includes a test for cure, which involves
comparison of total weight loss of a sample cured at
different length of exposure.
2. Precision

   Based on studies performed on laboratory samples
having 0 to 30% total volatiles (Vtot  ," see
Section 6.5), the intralaboratory absolute standard
deviation for total volatiles using this method
averaged 0.7 percent.  The interlaboratory precision
has not been determined.
3. Apparatus

   3.1  UV-Exposure Apparatus.  A conveyor-fed
ultraviolet curing apparatus.  The ultraviolet light
shall be provided by one or more medium-pressure

                          F 1

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mercury vapor lamps with quartz housings, capable of
providing light with a wavelength of between 200 and
400 ran.  The lamp and conveyor system must be capable
of providing sufficient exposure for the materials
being tested (see Section 4).   Other apparatus may be
used if approved by the Administrator.

   3.2  Oven.  A forced-draft oven capable of
maintaining a temperature of 110 ± 5°C for 1 hour.

   3.3  Thermometer.  A thermometer capable of
measuring oven temperature to ± 1°C.

   3.4  Balance.  A balance capable of weighing to
± 0.0001 g.

   3.5  Sample Dishes.  Circular flat-bottomed aluminum
foil weighing dishes, approximately 58 mm in diameter
by 18 mm high.

   3.6  Desiccator.  An airtight container, with
desiccant, large enough to contain samples dishes.

   3.7  Desiccant.  Calcium sulfate (e.g., indicating
Drierite* ) or equivalent desiccant.

   3.8  Disposable Pipettes.  Disposable 5-ml
polyethylene transfer pipettes.

   3.9  Acetone.  ACS reagent grade or equivalent.

   NOTE:  If acetone is not an adequate solvent for the
material being tested, another solvent with a
sufficiently low boiling point (< 60°C) may be used.
Solvent must be tested to determine if it evaporates
completely from the coating at room temperature;  i.e.,
the evaporative loss  (L_) should be greater than or
equal to zero  (see Section 6.2).

   3.10 Gloves. Talc-free disposable gloves.
4.    Procedure

   NOTE:    1) All  items that are weighed  (e.g., sample
            dish, pipettes) must be handled with gloves
            or sample tongs.
  Mention of  trade names or specific products does not
constitute  endorsement  by the Environmental Protection
Agency.

                          F 2

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           2.) Although many coatings can be handled in
           room lighting, highly sensitive coatings may
           exhibit curing with normal laboratory
           lighting.  The manufacturer should be
           consulted on handling precautions for such
           coatings.

4.1 Initial Analysis

   4.1.1  Condition the aluminum sample dishes by
heating them in a forced-draft oven at 110  ± 5°C for
at least 1 hour.  Remove the dishes and allow them to
cool in a desiccator.  Store the conditioned dishes in
a desiccator.

   4.1.2  Weigh an aluminum dish to ± 0.0001 g and
record this weight as W,.  Mix the coating thoroughly
and fill a disposable pipette with enough coating to
deliver 0.2 ± 0.1 g of coating.  Weigh the coating-
filled pipette to ± 0.0001 g and record this weight as
W2.  Place 3 ± 1 mL of acetone in the aluminum dish and
carefully add the coating into the dish.  Gently swirl
the dish to disperse the coating, taking care not to
spill any material.  Weigh the pipette after the sample
has been dispensed to ± 0.0001 g and record this weight
as W3.

        NOTE:  It may be difficult to dispense viscous
   samples from a pipette.   To achieve uniform sample
   weights  (i.e., ± 0.1 g), it may be helpful to place
   the sample dish on a balance and add the required
   amount of sample.  The acetone (or other solvent)
   would then be added to the sample and the dish
   swirled to disperse the sample uniformly.  Because
   of the possibility that volatiles might be lost
   during weighing, the sample weight W7 should still
   be calculated as described in Section 6.2.   An
   alternate procedure for viscous samples would be to
   use a syringe in place of the disposable pipette.
   4.1.3  Place the sample dish on a level surface at
room temperature in a laboratory fume hood for
30 minutes to allow the acetone to evaporate, then
weigh the sample dish to ± 0.0001 g and record this
weight as W4.  The evaporative loss (Le ,  Section 6.3)
should be greater than or equal to zero.

   NOTE: Some coatings, notably certain epoxy coatings,
may pick-up moisture during standing at room
temperature and thus show weight gain  (i.e., negative
values of Le).

                          F 3

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                                                       >
                                                       S -, *•
                                                         '
   4.1.4  Cure the coating by exposing it to UV light
doubling the length of exposure specified by the
manufacturer (i.e., doubling the number of passes
through the exposure apparatus at the manufacturer's
suggested conveyor-belt feed rate and lamp intensity).
Allow the sample to cool to room temperature
(approximately 30 seconds) between passes.  After all
the passes have been completed weigh the sample to
± 0.0001 g and record this weight as W5.

   4.1.5  After UV exposure and weighing, place the
sample dish in a 110 ± 5°C oven for 1 hour.  Remove the
sample dish and allow it to cool to room temperature  in
a desiccator.  Weigh the sample dish to ± 0.0001 g and
record this weight as W6/ then calculate Vtot  (percent)
as in Section 6.5.

   4.1.6  Analyze samples in triplicate and calculate
an average total organic content, Vtot  (percent)  as in
Section 6.6.

4.2 Subsequent Analysis

   4.2.1  Using fresh samples of the material from the
same lot as the sample in Section 4.1, repeat Section
4.1 using four times the manufacturer's recommended
length of exposure  (i.e., four times the number of
passes at the manufacturer's suggested curing
conditions). Calculate  Vtot  as  in Section 6.5.

   4.2.2  Analyze samples in triplicate and calculate
an average total organic content,   Vt0t  (percent)  as
in Section 6.6.

_  4.3 If the average total volatile organic content,
Vtot  (percent)  calculated in Section 4.1  does  not agree
to ± 1 percent  (absolute) with the one calculated  in
Section 4.2, repeat Section 4.2 doubling the last
length of exposure.  Compare to the prior exposure
results until the average total organic content,
Vtot  (percent)  of two consecutive exposures tested at
the same conveyor belt feed rate and lamp intensity
agree to ± 1 percent  (absolute).

   NOTE:  If the criterion has not been met by the
second time that Section 4.2 is repeated, the tester
may want to consider changing curing conditions  (i.e.,
conveyor belt feed  rate and lamp intensity) and repeat
Sections 4.1 through 4.3 beginning at twice the
manufacturer's recommended length of exposure with the
modified curing conditions.
                          F 4

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   4.4  Perform analyses in triplicate for each coating
until the criterion in Section 4.3 is met.  Record the
Vtot  values  used to meet  the criteria  in  Section 4.3
with the corresponding light intensity, conveyor-belt
feed rate, and number of passes.  Report the higher of
the two values obtained as  Vtot from  the sample being
tested.

   NOTE:  Underexposed UV-cured coatings may show
excessively high levels of total volatile organic
content,  Vtot (Section 6.5).   This may be corrected  by
adjusting the exposure level as described in Section
4.2.   Overexposed coatings may show charring,
discoloration, and bubbling.  This is often due to
thermal overexposure rather than UV overexposure.  To
reduce thermal effects,  lower intensity or increase the
conveyor belt feed rate,  and increase the number of
passes through the apparatus.  Allow the samples to
cool to room temperature (approximately 30 seconds)
between passes.

5. Calibration and Audits

   5.1  Analytical Balance.  Calibrate against standard
weights.

   5.2  Thermometer.  Calibrate against a National
Institute of Standards and Technology  (NIST)-traceable
thermometer.

   5.4  Audit Procedure.   Analyze the performance audit
sample, if available.  The same analyst,  analytical
reagents, and analytical system shall be used both for
compliance samples and the EPA audit samples.  If this
condition is met, auditing of subsequent compliance
analyses for the same enforcement agency within 30 days
is not required.  An audit sample set may not be used
to validate different sets of compliance samples under
the jurisdiction of different enforcement agencies,
unless prior arrangements are made with both
enforcement agencies.

   5.5  Audit Samples.  Audit samples will be supplied
only to enforcement agencies for compliance tests.  The
availability of audit samples may be obtained by
writing:  Source test Audit Coordinator  (MD-778),
Quality Assurance Division, Atmospheric Research and
Exposure Assessment Laboratory, U.S.  Environmental
Protection Agency, Research Triangle Park, NC  27711 or
by calling the Source Test Audit Coordinator (STAC) at
(919) 541-7834.  The request for the audit sample must
                          F 5

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be made at least 30 days prior to the scheduled
compliance sample analysis."

   5.6  Audit Results.  Calculate the audit sample
concentration according to the calculation procedure
described in the audit instructions included with the
audit sample.  Fill in the audit sample concentration
and the analyst's name on the audit response form
included with the audit instructions.  Send one copy to
the EPA Regional Office or the appropriate enforcement
agency and a second copy to the STAC.  The EPA Regional

Office or the appropriate enforcement agency will
report the results of the audit to the laboratory being
audited.  Include this response with the results of the
compliance samples in relevant reports to the EPA
Regional Office or the appropriate enforcement agency^
6.  Calculations

   6.1  Nomenclature.
   Le    = Evaporative loss, percent.
   LyV   = UV loss, percent.
   Vtot  = Total volatile organic content, percent.
   Vtotl  = Total volatile organic content of first
           sample, g.
   Vtot2  = Total volatile organic content of second
           sample, g.
   Vtot3  = Total volatile organic content of third
   _       sample, g.
   Vtot  = Average total volatile organic content,
           percent.
   Wj^    = Weight of empty aluminum sample dish, g.
   W2    = Weight of pipette and sample, g.
   W3    = Weight of pipette after sample has been
           dispensed, g.
   W5    = Weight of sample dish and sample after
           acetone has evaporated, g.
   W6    = Weight of sample dish and sample after UV
           exposure.
   W7    = Sample weight, g.
                          F 6

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                                                      SL> a
   6.2  Sample Weight  (W7).  The sample weight  is
calculated as the difference in the weight  of the
pipette before and after the sample has been delivered,
i.e.:


                        w7 * wz - w,
   6.3  Evaporative Loss.  The evaporative  loss (Le)  is
calculated as:
                       (W, + W, - W,)
                    Le - 1J	2	r x 100
                     c     \\f
   6.4  UV Processing Loss.  The UV processing loss
(Luv)  is calculated as:
   6.5  Total Volatiles.  The total  volatile organic
content is calculated as:
   6.6  Average Total Volatiles.   The  average of the
total volatiles Vtot is calculated for triplicate
samples as:
Report the average of the triplicate  analyses rounded
to +0.1 percent.
                           F  7

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7.   Bibliography

   1.  U.S. Environmental "Protection Agency, Method 24
 Determination of Volatile Matter Content. Water
Content, Density. Volume Solids, and Weight Solids of
Surface Coatings.  40 CFR 60, Appendix A.

   2.  American Society of Testing and Materials, ASTM
D2369-87. Standard Test Method for Volatile Content of
Coatings. Philadelphia, PA, 1987.

   3.  American Society for Testing and Materials.
Revised Test Methods for Determining VOC of Radiation
Curable Materials. ASTM proposed test method for UV/EB
curable materials (unpublished communications),
October 1991.
                          F 8

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