ASTM D4499-95(2000)
(Test Method)Standard Test Method for Heat Stability of Hot-Melt Adhesives
Standard Test Method for Heat Stability of Hot-Melt Adhesives
SCOPE
1.1 This test method covers the evaluation of hot-melt adhesives with respect to the change in properties that occurs while the adhesive is aged in the molten state during hot-melt application. Melt properties monitored are viscosity, color, skin formation, and phase separation.
1.2 The values stated in SI units are to be regarded as the 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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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation: D 4499 – 95 (Reapproved 2000)
Standard Test Method for
Heat Stability of Hot-Melt Adhesives
This standard is issued under the fixed designation D4499; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2.4 skin formation—appearanceofarelativelylooselayer
at the surface of a polymeric material.
1.1 This test method covers the evaluation of hot-melt
adhesives with respect to the change in properties that occurs
4. Summary of Test Method
while the adhesive is aged in the molten state during hot-melt
4.1 Samples of hot-melt adhesives are conditioned at the
application.Meltpropertiesmonitoredareviscosity,color,skin
adhesive manufacturer’s recommended application tempera-
formation, and phase separation.
ture for a conditioning cycle that corresponds to the expected
1.2 The values stated in SI units are to be regarded as the
residence time during which the adhesive will be held molten
standard.
in the storage and application equipment. If so specified by the
1.3 This standard does not purport to address all of the
adhesive manufacturer, the molten adhesive will be protected
safety concerns, if any, associated with its use. It is the
against exposure to air.The total residence time is divided into
responsibility of the user of this standard to establish appro-
two or three intervals at which points the aged adhesive color
priate safety and health practices and determine the applica-
and melt viscosity are measured and compared to the initial
bility of regulatory limitations prior to use.
adhesive color and viscosity. Prior to measuring the melt
2. Referenced Documents viscosity and color, the adhesive is subjectively evaluated for
evidence of phase separation and surface skinning. Separate
2.1 ASTM Standards:
adhesive samples are conditioned for each test period.
D907 Terminology of Adhesives
4.2 Thetestreportincludespercentchangeinmeltviscosity,
D1544 Test Method for Color of Transparent Liquids
3 ,4
percentofadhesivesurfaceskinned,percentchangeinGardner
(Gardner Color Scale)
color, and description of phase separation, if any.
D3236 Test Method for Apparent Viscosity of Hot-Melt
Adhesives and Coating Materials
5. Significance and Use
3. Terminology 5.1 Hot-melt adhesives must generally be applied at rela-
tively high temperatures in order that the adhesive viscosity is
3.1 Definitions—Several terms in this test method are de-
low enough that it can be readily handled in typical hot-melt
fined in accordance with Terminology D907.
equipment. Changes in the adhesive caused by exposure to the
3.2 Definitions of Terms Specific to This Standard:
severe environment required during hot-melt processing will
3.2.1 color—the aspect of the appearance of an object
disrupt the adhesive application process and may affect the
dependent upon the spectral composition of the incident light,
quality of the adhesive bond. Changes in adhesive viscosity
the spectral reflectance or transmittance of the object, and the
mayaffectthequantityofadhesivedispensedbytheapplicator.
spectral response of an observer.
Phase separation or changes in viscosity and color may be an
3.2.2 melt viscosity—measure of the ratio of shear stress to
indication of changes occurring in the adhesive which could
shear rate when the hot-melt is in its molten state.
affect the quality of the adhesive joint. A skin formed on the
3.2.3 phase separation—formation of a second liquid por-
adhesive may eventually clog the applicator nozzle or die.
tion from a previously homogenous liquid over time.
5.2 The data generated in this test procedure are compara-
tive in nature. Results can be useful in observing batch-to-
This test method is under the jurisdiction of ASTM Committee D-14 on batch variation or relative thermal stability of alternate adhe-
AdhesivesandisthedirectresponsibilityofSubcommitteeD14.50onHot-Meltand
sive formulations. Results can also be useful in selecting
Pressure-Sensitive Adhesives.
application equipment and establishing operating conditions
CurrenteditionapprovedMarch10,2000.PublishedNovember1995.Originally
for satisfactory handling of a particular hot-melt adhesive.
published as D4499–85. Last previous edition D4499–89.
Annual Book of ASTM Standards, Vol 15.06.
5.3 Round-robin testing showed that the reproducibility of
Annual Book of ASTM Standards, Vol 06.01.
this test method can depend strongly on the characteristics of
Visual color standards such as the Pantone Color System can be used in place
the adhesive being tested. Results showed that, for the particu-
of the Gardner Color System with pigmented adhesives.
Annual Book of ASTM Standards, Vol 05.02. lar adhesives tested in the round robin, the test method was
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
D 4499 – 95 (2000)
well suited for testing the heat stability of the adhesives based
Cycle I Cycle II
Initial (no preconditioning) Initial
on an EVA copolymer, a polyolefin, and a polyamide. How-
24 h 8 h
ever,becauseofpoorreproducibility,thetestmethodprovedto
48 h 18 h
be unsuitable for assessing the heat stability of the adhesive
96 h 24 h
48 h
based on a block copolymer. Precision of this test method is
discussed in Section 11.
8.3 Initial Data:
8.3.1 Melt Viscosity— Select a representative sample of
6. Apparatus
adhesive, as received from the manufacturer, and measure the
6.1 Glass Beakers, 300-mL, each approximately 6.6-cm
melt viscosity at the chosen conditioning temperature in
inside diameter by 11.7 cm high.
accordance with Test Method D3236. For some hot-melt
6.2 Mechanical Convection Oven, with specified tempera-
adhesives, the change in viscosity with aging can be affected
ture uniformity of 61°C (1.8°F).
bychangesinshearrate.Ifatallpossible,usethesamespindle
6.3 Viscometer, rotating-spindle type with leveling stand,
size and speed of rotation to measure the viscosity of the
stainless steel spindles, and sample chamber with precision
unaged and all of the heat-aged samples.
temperature controller which provides accuracy of 61.0°C or
8.3.2 Color:
better through the range from 100 to 200°C.
8.3.2.1 Nonpigmented Adhesives—FillaGardnercolortube
6.4 Eighteen Gardner Standards.
with slivers of the hot-melt adhesive in “as-received” condi-
6.5 Glass tubes, clear, 10.65-mm inside diameter, 114-mm
tion. Place the tube in an oven set at the minimum temperature
length.
necessary to produce a transparent melt. Remove the tube of
molten adhesive from the oven and immediately place into the
7. Sample Preparation
Gardner Color Comparator. Make the color determination, in
7.1 Large differences exist among hot-melt adhesives in accordance with Test Method D1544, before the adhesive
their hot-melt processing requirements. Many types of adhe- cools below the cloud point. Record the adhesive color to the
sives, such as those based on an unsaturated or a reactive nearest color unit.
polymer, can be held molten for only a short period of time. In 8.3.2.2 Pigmented Adhesives—Place about 150 g of adhe-
some cases, these adhesives must be protected against expo- sive in “as-received” condition into a 300-mL beaker. Heat in
sure of the hot adhesive to the atmosphere. Other types of an oven to the manufacturer’s recommended application tem-
adhesives, such as those based on a saturated polymer, can be perature, and stir the adhesive thoroughly to ensure uniform
heldmoltenandunprotectedfromtheatmosphereforextended pigment dispersion.Avoid aeration of the adhesive. Prepare an
periods of time. The adhesive manufacturer’s recommenda- adhesive film 0.25 mm (0.010 in.) thick on white paper. Select
tionsonexposuretimeandtemperatureandtheneedtoprotect appropriate visual color standards such as the Pantone Color-
the molten adhesive against exposure to air must be followed. Matching System. Identify the color chip that most closely
7.2 Repeated melting or extended storage of a hot-melt matches the initial adhesive color.
adhesive will adversely affect the product’s performance in a
NOTE 1—The adhesive supplier and adhesive user can jointly prepare
heat-stability test. Choose a representative sample material
custom-made color standard for individual adhesives to be tested.
from batches recently received from the manufacturer.
8.4 Sample Preparation—Weigh 150 g of adhesive into a
7.3 Avoid contamination of adhesive with water to prevent
300-mL beaker and place in the oven. Glass beakers are used
foaming problems during melting and possible reactivity with
instead of metal containers to allow the observation of phase
adhesive components.
separation. Prepare three samples for Test Cycle I or four
samples for Test Cycle II. Cover the samples with aluminum
8. Procedure
foil prior to placement in the oven. If the use of an inert gas
8.1 Test Temperature— Set oven and viscometer tempera-
atmosphere during molten processing is recommended by the
turecontrolleratadhesivemanufacturer’srecommendedappli-
adhesive manufacturer, provide a continuous inert gas pur
...
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