ASTM D5179-98
(Test Method)Standard Test Method for Measuring Adhesion of Organic Coatings to Plastic Substrates by Direct Tensile Testing
Standard Test Method for Measuring Adhesion of Organic Coatings to Plastic Substrates by Direct Tensile Testing
SCOPE
1.1 This test method covers the laboratory determination of organic coating adhesion to plastic substrates by mounting and removing an aluminum stud from the surface of the coating and measuring the force required to break the coating/substrate bond with a tensile tester.
1.2 This test method requires that the aluminum stud be glued directly to the surface of a coated, cured panel (Fig. 1).
1.3 This test method is used to compare the adhesion of coatings to various plastic substrates, thus allowing for a quantitative comparison of various coating/substrate combinations.
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Standards Content (Sample)
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Designation: D 5179 – 98
Standard Test Method for
Measuring Adhesion of Organic Coatings to Plastic
Substrates by Direct Tensile Testing
This standard is issued under the fixed designation D 5179; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the laboratory determination of
organic coating adhesion to plastic substrates by mounting and
removing an aluminum stud from the surface of the coating and
measuring the force required to break the coating/substrate
bond with a tensile tester.
1.2 This test method requires that the aluminum stud be
adhered directly to the surface of a coated, cured panel (Fig. 1).
1.3 This test method is used to compare the adhesion of
coatings to various plastic substrates, thus allowing for a
FIG. 1 Direct Tensile Model
quantitative comparison of various coating/substrate combina-
tions.
1.4 Other tensile test methods are Test Method D 4541 and
tester equipped with an upper coupling adapter (Fig. 2), and a
ISO 4624 (but are not technically equivalent).
1.5 The values stated in inch-pound units are to be regarded
as the standard. The values given in parentheses are for
information only.
1.6 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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D 4541 Test Method for Pull-Off Strength of Coatings
Using Portable Adhesion Testers
2.2 Other Standard:
ISO 4624 Paints and Varnishes—Pull-off test for adhesion
3. Summary of Test Method
FIG. 2 Upper Coupling Adaptor
3.1 An aluminum stud is bonded directly to a coated cured
panel. The adhesive is allowed to cure for 2 h at room
temperature. The specimen is then subjected to test on a tensile
restraining device (Fig. 3).
3.2 If a coating is to fulfill its function of protecting or
decorating a substrate, it must adhere to it for the expected
This test method is under the jurisdiction of ASTM Committee D-1 on Paint
service life. Because the substrate and its surface preparation
and Related Coatings, Materials, and Applications and is the direct responsibility of
(or lack of it) has a drastic effect on the adhesion of coatings,
Subcommittee D01.23 on Physical Properties of Applied Paint Films.
Current edition approved June 10, 1998. Published September 1998. Originally
a method of evaluation adhesion of a coating to different
published as D 5179 – 91. Last previous edition D 5179 – 97a.
substrates or surface treatments, or of different coating to the
Annual Book of ASTM Standards, Vol 06.02.
same substrate and treatment, is of considerable usefulness in
Available from American National Standards Institute, 11 W. 42nd St., 13th
Floor, New York, NY 10036. the industry.
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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D5179–98
FIG. 3 Direct Tensile Restraining Device
4. Significance and Use 5.6 Adhesive, cyanoacrylate adhesive . Since cyanoacrylate
adhesives lose adhesive bond strength with time, do not use
4.1 The pull-off strength (commonly referred to as adhe-
previously opened containers or lots of adhesive known to be
sion) of a coating is an important performance property that has
old.
been used in specifications. This test method serves as a means
5.7 Two-Kilogram Weight, approximately 2 in. (50 mm) in
for uniformly preparing and testing organic coatings on plastic
diameter and 5 in. (130 mm) in height.
substrates. Further information may be found in Appendix X1.
6. Preparation and Conditioning of Specimen
5. Apparatus and Materials
5 6.1 Sanding Procedure—Sand the large face of stud with
5.1 Tensile Tester, commercially available.
80-grit sandpaper, making certain that the surface is uniformly
5.2 Aluminum Stud—The shape and dimensions of the stud
roughened. When sanding studs, sand straight up and down;
are shown in Fig. 1.
rotate stud one quarter of a turn and continue sanding. Make
5.3 Upper Coupling Adaptor—The apparatus is shown in
certain the surface of the stud is flat but rough. While sanding,
3 1
Fig. 2. The adaptor is 3 ⁄4 in. (94 mm) long, 1 ⁄4 in. (31 mm)
keep the stud face parallel to the sandpaper. Nonplanar surfaces
in diameter at the top, and 1 in. (25 mm) in diameter at the
cannot be used in testing because they lead to nonuniform
bottom. The hole, indicated by “B,” is used to attach the
bonding of the stud to the coated surface. Only flat (planar)
adaptor to the tensile tester load cell. The hole has a ⁄2-in.
studs should be used in testing. Planarity may be assessed by
(13-mm) diameter. The machined opening indicated by “A,” is
placing a stud on a flat surface and checking to see if the stud
to receive the head of the aluminum stud.
wobbles. Careful preparation of studs is essential for good
5.4 Restraining Device—The apparatus is shown in Fig. 3A
adhesive adhesion.
and 3B. The ⁄2-in. (13-mm) diameter hole, marked “A,” in the
6.2 Cleaning Procedure—Place sanded studs in a large
1 1
2 ⁄2-in. (63.5-mm) long, 1 ⁄4-in. (31-mm) diameter lower
beaker. Pour technical grade acetone over the studs and swirl
coupling adapter, is used to mount the device in the tensile
the beaker to completely wash the studs. Pour out acetone and
tester. The top portion is 4 in. (100 mm) in diameter, ⁄4 in. (19
repeat the cleaning procedure. Soak the stud for at least 15 min,
mm) high, and is fitted with a hole slightly larger than ⁄4 in. (19
pour out the acetone, and allow the studs to dry.
mm) in diameter to allow stud clearance. The bottom screw
6.3 Place washed and dried studs and beaker in an oven at
portion is machined to fit with the top portion and is ⁄2 in. (13
120°C and allow to heat for 1 h. Remove the beaker and studs
mm) thick. Fig. 3C illustrates the final appearance of the test
from the oven and allow to cool. DO NOT TOUCH FACE OF
assembly before it is tested.
STUDS.
5.5 Wooden Applicators, used to clean the adhesive from
around the aluminum stud.
Elmer’sy Wonder Bond Plusy Super Glue, a cyanoacrylate adhesive sold by
Elmer’s Products, Inc., 180 E. Broad St., Columbus, OH 43215, was found
Gray, K. N., Buckley, S. E., and Nelson, G. L., “Accessing Measurement acceptable in the round-robin study upon which this test method is based. Other
Standards for Coating Adhesion to Plastics,” Modern Paint and Coatings Journal, adhesives may be used if they provide adequate adhesion between the aluminum
Vol 75, No. 10, October 1985, p. 160. stud and the coating being tested; the results reported in the Precision and Bias
The sole source of supply of the wooden puritan applicators, in sizes 6 in. (150 Section, however, may not apply. From other work it is noted that some
mm) in length and 0.007 in. (2 mm) in diameter, known to the committee at this time cyanoacrylate adhesives may penetrate certain coatings and soften the coating or the
is Hardwood Products Co., Guilford, ME 04443. If you are aware of alternative plastic substrate. The same is true for other adhesives. Care in observation of
suppliers, please provide this information to ASTM Headquarters. Your comments unusual results is necessary to ensure against the possibility of error. This latter is
will receive careful consideration at a meeting of the responsible technical to be suspected if an adhesive gives an unexpectedly low result. Adhesives that yield
committee, which you may attend. a brittle adhesive layer should not be used.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D5179–98
6.4 Spread four drops of cyanoacrylate adhesive on the 7.5.2 Cohesive failure in the coating, C,
large face of an aluminum stud. Next, quickly press the stud 7.5.3 Combination of adhesive failure at the coating/
onto the coated test substrate. Place a 2-kg weight on the stud substrate interface and cohesive failure in the coating, AC,
to ensure good contact between the stud, adhesive, and surface 7.5.4 Adhesive failure at the stud, S, and
of the coating. Clean the excess adhesive from the edge of the 7.5.5 Combination of adhesive failure at the stud and
stud with a wooden applicator. Carefully remove the weight cohesive failure in the coating, CS.
after 2 min. 7.6 For multilayer coatings, note if the failure is between the
layers. If so, label as CM.
NOTE 1—Substrate panels may be cut to any size that fits the restraining
7.7 Number and retain all test specimens for adhesion
device.
failure calculations. Test five specimens of each coated sub-
NOTE 2—When the stud is pressed, excess adhesive should escape from
under the stud. Excess adhesive buildup at the edge of the stud is a major strate one day and five on a second day. If one specimen differs
source of error if allowed to dry. This excess must be removed from
significantly from the other four at the same time, fails because
around the stud. The adhesive may be removed using a wooden applicator
of an uneven (nonplanar) stud, or for any other reason performs
and an absorbent, creped, low-lint material. Some workers have found
unlike the other four, test a replacement specimen.
cotton swabs also work well when removing the excessive adhesive.
NOTE 6—Examine the stud and specimen carefully. Adhesive should
6.5 Allow the sample to cure for2hat room temperature
have been applied uniformly to the entire stud surface. Coating should
(see Note 3).
have pulled off uniformly over the entire stud surface either with adhesive
failure from the substrate (A) or cohesive failure in the coating (C). If
NOTE 3—The time specified led to the results reported in the Precision
failure is less than 90 % A or C or (or CM), if the adhesive has failed at
and Bias Section. If other than the recommended adhesive is used, the user
the stud, retest exercising particular care in the specimen and stud
should be guided by the cure time recommended by the adhesive
preparation.
manufacturer. A series of preliminary tests at several cure times may be
NOTE 7—The percentage of adhesive failure at the coating/substrate
necessary in the selection of a time that ensures cure of the adhesive used.
interface is determined by inspecting the tested area on the substrate. This
NOTE 4—When reusing aluminum studs, the studs must be soaked in
may be assessed by overlaying a transparent sheet grid marked in 0.10-in.
acetone to remove the coating and resanded. It has been found that
(2.54-mm) squares and estimating the percentage of adhesive failure in
soaking the studs in two separate acetone baths thoroughly removes the
each square that lies over the tested area. These percentages may then be
adhesive and coating. The first acetone bath is used to dissolve the
averaged to obtain failure for each specimen.
cyanoacrylate adhesive, and the second is used to further clean and
NOTE 8—Sample conditioning, if any, and humidity and temperature of
dissolve any coating or adhesive left on the stud. Before the studs are used,
test room may affect results. Notation of these conditions should be made
they should be resanded and cleaned with acetone as specified in 6.2, 6.3,
on the test report.
and 6.4.
6.6 Conditioning—Condition the coated substrates for at
8. Report
least 24 h at 23 6 2°C (73.5 6 3.5°F) and 50 6 5 % relative
8.1 Report the number of tests, the maximum stress ob-
humidity, and test in the same environment or immediately on
tained in each test, and the type of failure. Test data sheet is
removal therefrom, unless otherwise specified by the purchaser
shown in Fig. 4. Fill in data sheet with results obtained from
and the seller.
each test. Attach tensile test traces to the data sheets. Calculate
and report mean and standard deviation for tensile strength for
7. Procedure
each coating/substrate combination tested.
7.1 Install the restraining device and upper adaptor in the
tensile tester.
9. Precision and Bias
7.2 Calibrate the tensile tester. Make sure that the chart
9.1 The precision and bias are primarily dependent upon the
speed is set at 8 to 20 in./min (20 to 50 cm/min). Make sure that
accuracy of the force measurements, the alignment of the
the crosshead speed is set at 2 in./min (5 cm/min). Make sure
device, the care exercised in stud and specimen preparation,
that the chart full scale is set at 100 kg.
and the care in testing.
7.3 Place the specimen to be tested in the restraining device
9.2 A round robin involving five different types of coatings
(Fig. 3A and 3B). Pre-position the crosshead and then slowly
and seven different plastic substrates, and ten different labora-
lower it so the upper coupling adaptor can be attached to the
tories yielded interlaboratory reproducibility data as shown in
test specimen. Take care to prevent the crosshead from
Table 1. Within laboratory repeatability data is shown in Table
impacting into the top of the specimen. Carefully attach the
2 and Table 3.
upper coupling adaptor to the stud (Fig. 3C).
10. Keywords
NOTE 5—When testing thin substrates, a piece of plastic may be placed
in the restraining device behind the test specimen to prevent the substrate
10.1 adhesion; bond strength; cyanoacrylate adhesive; plas-
from flexing when the stud is pulled from it.
tic substrate; pull-off strength; pull testing; tensile tester
7.4 Turn on the chart recorder and pen. Start the tensile test.
Stop the test when the stress returns to zero on the chart.
A complete report with additional data is available. See Nelson, G. L., “Testing
7.5 Examine the test area on each specimen to determine the
of EMI/RFI Coating Adhesion to Plastics by a Tensile Test Method,” Final Report
type of coating failure, rating it according to the following:
for Computer and Business Manufacturers Association and Society of the Plastics
7.5.1 Adhesive failure of the coating at the substrate, A, Industry, University of Southern Mississippi, June, 1989.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D5179–98
FIG. 4 C
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