ASTM D7767-11
(Test Method)Standard Test Method to Measure Volatiles from Radiation Curable Acrylate Monomers, Oligomers, and Blends and Thin Coatings Made from Them
Standard Test Method to Measure Volatiles from Radiation Curable Acrylate Monomers, Oligomers, and Blends and Thin Coatings Made from Them
SIGNIFICANCE AND USE
This test method is an extension of Test Method D5403. While Test Method D5403 specifies that a test specimen be cured by exposure to UV or EB as prescribed by the supplier of the material, most radiation curable monomers and oligomers provided as raw materials to formulators are not designed to be used alone but rather as blends of monomers and oligomers so that there are no “supplier prescribed” exposure conditions. Test Method D5403 is not appropriate for the measurement of volatiles from thin radiation-curable coatings because supplier prescribed cure conditions include both a thickness and an exposure specification which are difficult or impossible to achieve in a test lab. Furthermore, inks form a special class of thin radiation curable coatings because they are formulated with known interferences (for example, pigments). As a result, Test Method D5403 does not provide a method for measuring volatiles from monomers and oligomers used as raw materials in the formulation of radiation curable coatings nor does it provide a method for measuring volatiles from thin radiation curable coatings such as inks.
This test method provides a means to measure the volatile content of individual acrylate monomers, oligomers, and blends commonly used to formulate radiation curable coatings such as printing inks. Such coatings comprise liquid or solid reactants that cure by polymerizing, crosslinking, or a combination of both and are designed to be applied as thin coatings in the absence of water or solvent and to be cured by exposing to ultraviolet radiation. There is currently no direct method for measuring the volatiles from the individual materials used or thin coatings made from them.
This test method also provides a means to measure the volatiles from acrylate monomers, oligomers, and blends cured using ultraviolet radiation from which an estimate for the volatiles from a thin coating cured using ultraviolet radiation comprising these acrylate monomers, oligomers, and ...
SCOPE
1.1 This test method describes a means to determine the percentage of processing, potential, and total volatiles from radiation curable acrylate monomers, oligomers, and blends. The results can be used to estimate the volatiles from thin radiation curable coatings that cannot otherwise be measured with the restriction that those coatings are not subjected to a pre-exposure water or solvent drying step. It also provides a means to determine the volatiles of thin radiation curable coatings in the absence of known interferences such as pigments in inks.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D7767 − 11
Standard Test Method to
Measure Volatiles from Radiation Curable Acrylate
Monomers, Oligomers, and Blends and Thin Coatings Made
from Them
This standard is issued under the fixed designation D7767; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.2 Other Document:
EPA Method 24 Determination of Volatile Matter Content,
1.1 This test method describes a means to determine the
WaterContent,Density,VolumeSolids,andWeightSolids
percentage of processing, potential, and total volatiles from
of Surface Coatings
radiation curable acrylate monomers, oligomers, and blends.
The results can be used to estimate the volatiles from thin
3. Terminology
radiation curable coatings that cannot otherwise be measured
3.1 Definitions:
with the restriction that those coatings are not subjected to a
3.1.1 cure, n—conversion of a coating from its application
pre-exposure water or solvent drying step. It also provides a
state to its final use state measured by tests generally related to
means to determine the volatiles of thin radiation curable
end use performance and mutually agreeable to supplier and
coatings in the absence of known interferences such as
purchaser.
pigments in inks.
3.1.2 electron beam (EB) curing, n—conversionofacoating
1.2 The values stated in SI units are to be regarded as
from its application state to its final use state by means of a
standard. No other units of measurement are included in this
mechanism initiated by electron impingement generated by
standard.
equipment designed for that purpose.
1.3 This standard does not purport to address all of the
3.1.3 pigment, n—an insoluble substance added to a formu-
safety concerns, if any, associated with its use. It is the
lation to modify the visual appearance of a coating made from
responsibility of the user of this standard to establish appro-
the formulation.
priate safety and health practices and determine the applica-
3.1.4 potential volatiles, n—the percentage loss in specimen
bility of regulatory limitations prior to use.
weightuponheatingat110°Cfor60minafterradiationcuring.
3.1.5 processing volatiles, n—the percentage loss in speci-
2. Referenced Documents
men weight under process conditions that are designed to
2.1 ASTM Standards:
simulate actual industrial cure processing conditions.
D5403 Test Methods for Volatile Content of Radiation Cur-
3.1.6 retained weight, n—the mass of specimen remaining
able Materials
after exposing to the UV source, heating in an oven, or both.
E145 Specification for Gravity-Convection and Forced-
3.1.7 thin, adj—less than 15 micrometres in thickness.
Ventilation Ovens
E177 Practice for Use of the Terms Precision and Bias in
3.1.8 total volatiles, n—the percentage loss in specimen
ASTM Test Methods
weight under process conditions that are designed to simulate
E691 Practice for Conducting an Interlaboratory Study to
actualindustrialcureprocessingconditionsandafterheatingat
Determine the Precision of a Test Method
110°C for 60 min.
3.1.9 ultraviolet (UV) curing, n—conversion of a coating
from its application state to its final use state by means of a
This test method is under the jurisdiction of ASTM Committee D01 on Paint mechanism initiated by ultraviolet radiation in the range from
and Related Coatings, Materials, andApplications and is the direct responsibility of
200 to 400 nm generated by equipment designed for that
Subcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.
purpose.
Current edition approved Nov. 1, 2011. Published November 2011. DOI:
10.1520/D7767-11.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
Standards volume information, refer to the standard’s Document Summary page on 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
the ASTM website. www.access.gpo.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7767 − 11
3.1.10 UVA, n—the region of the electromagnetic spectrum common exposure step involving a specified amount of ultra-
comprising wavelengths falling in the range between 320 and violet radiation in a specific spectral range using a common
390 nm. photoinitiator is called for.
5.5 If desired, volatile content can be determined as two
4. Summary of Test Method
separate components: processing volatiles and potential vola-
4.1 Adesignated quantity of an acrylate-functional material
tiles. Processing volatiles are a measure of volatile loss during
(test specimen) is weighed in a container lid before and after a
the actual cure process. Potential (or residual) volatiles are a
UV exposure step sufficient to ensure a thorough cure of the
measure of volatile loss that might occur upon aging or under
test specimen to obtain the percent solids retained. The
extreme storage conditions. These volatile content measure-
calculated percentage weight loss is attributed to process
mentsmaybeusefultotheproducerofamaterial,aformulator
volatiles. The test specimen and container lid are weighed
using such materials, or to environmental interests for deter-
again after heating for 60 min at 110 6 5°C to obtain the
mining and reporting emissions.
percent solids retained.Any additional weight loss is attributed
5.6 The validity of this test method for non-acrylated
to potential volatiles.The total volatiles for a test specimen are
radiation-curable chemistries such as methacrylates, thiol-ene,
the difference between the initial sample mass and the retained
vinyl ethers, and epoxies cured using ultraviolet radiation has
mass after exposing and heating divided by the initial mass.
not been verified. Use of an electron beam to cure the acrylate
5. Significance and Use
monomers, oligomers, and blends or thin coatings made from
them, including inks, has not been verified using this method
5.1 This test method is an extension ofTest Method D5403.
While Test Method D5403 specifies that a test specimen be and cannot be assumed.
cured by exposure to UV or EB as prescribed by the supplier
of the material, most radiation curable monomers and oligom- 6. Interferences
ers provided as raw materials to formulators are not designed
6.1 The degree to which the results of this procedure
to be used alone but rather as blends of monomers and
accurately measure the volatiles emitted is absolutely depen-
oligomers so that there are no “supplier prescribed” exposure
dent upon proper cure during the test procedure. Although
conditions. Test Method D5403 is not appropriate for the
overcure will have little or no effect upon measured volatiles,
measurement of volatiles from thin radiation-curable coatings
undercure may lead to erroneously high values. To minimize
because supplier prescribed cure conditions include both a
variability in the cure conditions, an ultraviolet source provid-
thickness and an exposure specification which are difficult or
ing a given irradiance in a specific spectral region and an
impossible to achieve in a test lab. Furthermore, inks form a
exposure energy is specified as is a photoinitiator and concen-
specialclassofthinradiationcurablecoatingsbecausetheyare
tration.
formulated with known interferences (for example, pigments).
6.2 The presence of strong ultraviolet absorbing non-
As a result, Test Method D5403 does not provide a method for
acrylate species such as pigments and ultraviolet blockers can
measuringvolatilesfrommonomersandoligomersusedasraw
interfere with the ability of this test procedure to accurately
materials in the formulation of radiation curable coatings nor
measure volatiles. These additives are designed to absorb,
does it provide a method for measuring volatiles from thin
reflect, luminesce, or scatter visible or ultraviolet radiation.
radiation curable coatings such as inks.
Suchadditivesinterferewiththepropercureofmaterialstested
5.2 This test method provides a means to measure the
using this method and are to be avoided.
volatile content of individual acrylate monomers, oligomers,
6.3 Photoinitiators are strong ultraviolet absorbers but their
and blends commonly used to formulate radiation curable
presence is required for proper curing.
coatings such as printing inks. Such coatings comprise liquid
or solid reactants that cure by polymerizing, crosslinking, or a
7. Apparatus
combination of both and are designed to be applied as thin
coatings in the absence of water or solvent and to be cured by
7.1 Container Lids, metal can lids having an OD of 35 mm
exposing to ultraviolet radiation. There is currently no direct
and a height of 14 mm with a 25 mm diameter protrusion
method for measuring the volatiles from the individual mate-
which, when inverted, creates a 0.6 mm deep, 25 mm diameter
rials used or thin coatings made from them.
well.
5.3 This test method also provides a means to measure the
7.2 Forced Draft Oven, Type IIA or IIB as specified in
volatiles from acrylate monomers, oligomers, and blends cured
Specification E145.
using ultraviolet radiation from which an estimate for the
7.3 Ring Stand, a device designed to support items using
volatiles from a thin coating cured using ultraviolet radiation
various clamps.
comprising these acrylate monomers, oligomers, and blends
can be calculated. A common exposure step involving a
7.4 Versatile Clamp, a 3-pronged clamp with adjustable
specified amount of ultraviolet radiation in a specific spectral
closure for holding items.
range using a common photoinitiator is called for.
5.4 This test method further provides a means to measure
the volatiles from thin radiation-curable coatings such as inks
Metal can lids for this method can be obtained from SKS Bottle & Packaging
in the absence of known interferences such as pigments. A (Watervliet, NY).
D7767 − 11
FIG. 1 Photo of Fiber Alignment Relative to Metal Lid During Exposure
7.5 Ultraviolet Radiation Source, the focused output from a heighttoachieveaUVApeakirradianceof115 615mW/cm .
short-arc 200W Xe/Hg bulb delivered by a quartz fiber guide. Once positioned, the fiber should not be moved relative to the
mark (8.2).
7.6 Radiometer, a device able to measure irradiance and
energy in the UVA spectral region.
8.4 Position the radiometer window (7.6) on the mark (8.2)
and measure the UVA energy after an 80 s exposure. If
7.7 Balance, an instrument capable of weighing a mass to
necessary, adjust the exposure time to achieve a UVA target
the nearest 0.1 mg.
energy of 9.0 6 0.2 joules/cm . This determination should be
7.8 Gloves, personal protective wear for handling chemi-
repeated daily to verify proper exposure conditions.
cals.
7.9 Forceps or Tongs,ameanstohandleaspecimenwithout
9. Procedure
direct contact in order to minimize mass transfer.
9.1 Dissolve 2.0 % by weight of ethyl-2,4,6-
7.10 Spreading Tool, a small metal or PTFE spatula or a
trimethylbenzoyphenylphosphinate (TPO-L) photoinitiator in
wooden applicator stick for spreading resin.
the material to be tested. Mix thoroughly to ensure homoge-
neity. Store the test specimen in a dark container.
8. Preparation of Apparatus
9.2 Precondition the container lids for 30 min at 110 6 5°C
8.1 The tip of the quartz fiber guide shall be positioned
and store in a desiccator prior to use.
normal to the center of a container lid (7.1) at a height of
approximately 80 to 85 mm from the container lid to provide
9.3 Weigh a preconditioned container lid (7.1) to 0.1 mg
an illuminated circular area of approximately 40 to 45 mm in
(A). Use gloves, forceps, or tongs to handle the container lid.
diameter in the plane on which the container lid (7.1) sets in
9.4 Place the container lid upside down on the balance pan
order to approximate uniform irradiance of the test specimen.
and add 0.2 6 0.02 g of the test specimen (9.1) to the recessed
8.2 Identify the approximate center of the illuminated area
area. Spread the test specimen using a spreading tool to ensure
with a mark which will later assist in positioning of a container
uniform coverage of the recessed area. Do not allow the test
lid with a test specimen.A25 mm filter paper disk taped to the
specimen to contact any surface of the container lid outside of
work area surface works well for this.Aproper setup is shown
therecessedarea.Weighthecontainerlidwithtestspecimento
in Fig. 1.
0.1 mg (B).
NOTE 1—Placement of a mark is best accomplished with the shutter
NOTE 2—It is helpful to hold the container lid with one hand using
open. Wear appropriate eye protection before opening the shutter and
gloves, forceps, or tongs while spreading the test specimen with the
placing the mark.
spreading tool in the other. The elapsed time between spreading and
8.3 Centertheopticalwindowoftheradiometeronthemark
weighing should be no greater than 60 s. If the sample to be tested
contains any reactive diluent with a vapor pressure at room temperature
(8.2). Using the ultraviolet radiation source (7.5) set at 100 %
greaterthan1.0mmHg,theelapsedtimebetweenspreadingandweighing
power with the fiber (8.1) and radiometer optical window (7.6)
must be no greater than 30 s.
properly aligned, open the shutter and measure the UVA peak
NOTE 3—Low viscosity test specimens spread easily and a uniform
irradiance at the sample plane. If necessary, adjust the fiber
thicknesscanbeobtained.Highviscositytestspecimensaremoredifficult
to work with but it is important to spread as evenly as is practical. Air
bubbles shall be removed, if possible.
This test method was developed using an LC-8 SpotCure source from
9.5 Center the container lid with test specimen on the mark
Hamamatsu Corporation (Bridgewater, NJ).
Power Puck II from EIT (Sterling, VA). (8.2) using gloves, forceps, or tongs, being careful not to
D7767 − 11
TABLE 1 Calculation of Estimated Volatiles for a Coating using Method A
Total Percent Volatiles
Weight Percentage Total Percent Volatiles
for each Monomer,
Reactive Components of each Monomer, in Composition
Oligomer, or
in Composition Oligomer, or Blend based on
Blend in the
in the Composition Weight Percentages
Composition (10.2.1)
Acrylate 1 30.0 1.67 0.50
Acrylate 2 60.0 0.43 0.26
Acrylate 3 10.0 3.14 0.31
Totals 100.0 NA 1.07
TABLE 2 Determination of Volatiles from Blends and Fully Formulated Coatings using Method B
Weight Percentage Weight Percentage Total Pe
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