ASTM F1921/F1921M-12e1
(Test Method)Standard Test Methods for Hot Seal Strength (Hot Tack) of Thermoplastic Polymers and Blends Comprising the Sealing Surfaces of Flexible Webs
Standard Test Methods for Hot Seal Strength (Hot Tack) of Thermoplastic Polymers and Blends Comprising the Sealing Surfaces of Flexible Webs
SIGNIFICANCE AND USE
5.1 In form-fill operations, sealed areas of packages are frequently subject to disruptive forces while still hot. If the hot seals have inadequate resistance to these forces, breakage can occur during the packaging process. These test methods measure hot seal strength and can be used to characterize and rank materials in their ability to perform in commercial applications where this quality is critical. ^SCOPE:
1.1 These two test methods cover laboratory measurement of the strength of heatseals formed between thermoplastic surfaces of flexible webs, immediately after a seal has been made and before it cools to ambient temperature (hot tack strength).
1.2 These test methods are restricted to instrumented hot tack testing, requiring a testing machine that automatically heatseals a specimen and immediately determines strength of the hot seal at a precisely measured time after conclusion of the sealing cycle. An additional prerequisite is that the operator shall have no influence on the test after the sealing sequence has begun. These test methods do not cover non-instrumented manual procedures employing springs, levers, pulleys and weights, where test results can be influenced by operator technique.
1.3 Two variations of the instrumented hot tack test are described in these test methods, differing primarily in two respects: (a) rate of grip separation during testing of the sealed specimen, and (b) whether the testing machine generates the cooling curve of the material under test, or instead makes a measurement of the maximum force observed following a set delay time. Both test methods may be used to test all materials within the scope of these test methods and within the range and capacity of the machine employed. They are described in Section 4.
1.4 SI units are preferred and shall be used in referee decisions. Values stated herein in inch-pound units are to be regarded separately and may not be exact equivalents to SI units. Therefore, each system shall ...
SCOPE
1.1 These two test methods cover laboratory measurement of the strength of heatseals formed between thermoplastic surfaces of flexible webs, immediately after a seal has been made and before it cools to ambient temperature (hot tack strength).
1.2 These test methods are restricted to instrumented hot tack testing, requiring a testing machine that automatically heatseals a specimen and immediately determines strength of the hot seal at a precisely measured time after conclusion of the sealing cycle. An additional prerequisite is that the operator shall have no influence on the test after the sealing sequence has begun. These test methods do not cover non-instrumented manual procedures employing springs, levers, pulleys and weights, where test results can be influenced by operator technique.
1.3 Two variations of the instrumented hot tack test are described in these test methods, differing primarily in two respects: (a) rate of grip separation during testing of the sealed specimen, and (b) whether the testing machine generates the cooling curve of the material under test, or instead makes a measurement of the maximum force observed following a set delay time. Both test methods may be used to test all materials within the scope of these test methods and within the range and capacity of the machine employed. They are described in Section 4.
1.4 SI units are preferred and shall be used in referee decisions. Values stated herein in inch-pound units are to be regarded separately and may not be exact equivalents to SI units. Therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.5 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 o...
General Information
Standards Content (Sample)
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Designation: F1921/F1921M − 12
Standard Test Methods for
Hot Seal Strength (Hot Tack) of Thermoplastic Polymers and
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Blends Comprising the Sealing Surfaces of Flexible Webs
ThisstandardisissuedunderthefixeddesignationF1921/F1921M;thenumberimmediatelyfollowingthedesignationindicatestheyear
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.
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ε NOTE—Designation was corrected editorially in October 2013.
1. Scope 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 These two test methods cover laboratory measurement
responsibility of the user of this standard to establish appro-
of the strength of heatseals formed between thermoplastic
priate safety and health practices and determine the applica-
surfaces of flexible webs, immediately after a seal has been
bility of regulatory limitations prior to use. The operator of the
made and before it cools to ambient temperature (hot tack
equipment is to be aware of pinch points as the seal jaws come
strength).
together to make a seal, hot surfaces of the jaws, and sharp
1.2 These test methods are restricted to instrumented hot instruments used to cut specimens. It is recommended that the
tack testing, requiring a testing machine that automatically
operator review safety precautions from the equipment sup-
heatseals a specimen and immediately determines strength of plier.
thehotsealatapreciselymeasuredtimeafterconclusionofthe
2. Referenced Documents
sealing cycle. An additional prerequisite is that the operator
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shall have no influence on the test after the sealing sequence
2.1 ASTM Standards:
has begun. These test methods do not cover non-instrumented
D882 Test Method for Tensile Properties of Thin Plastic
manual procedures employing springs, levers, pulleys and
Sheeting
weights, where test results can be influenced by operator
E171 Practice for Conditioning and Testing Flexible Barrier
technique.
Packaging
E691 Practice for Conducting an Interlaboratory Study to
1.3 Two variations of the instrumented hot tack test are
Determine the Precision of a Test Method
described in these test methods, differing primarily in two
F88 Test Method for Seal Strength of Flexible Barrier
respects: (a) rate of grip separation during testing of the sealed
Materials
specimen, and (b) whether the testing machine generates the
F2029 Practices for Making Heatseals for Determination of
cooling curve of the material under test, or instead makes a
Heatsealability of Flexible Webs as Measured by Seal
measurement of the maximum force observed following a set
Strength
delay time. Both test methods may be used to test all materials
withinthescopeofthesetestmethodsandwithintherangeand
3. Terminology
capacity of the machine employed. They are described in
3.1 Definitions:
Section 4.
3.1.1 adhesive failure, n—a failure mode in which the seal
1.4 SI units are preferred and shall be used in referee
failsattheoriginalinterfacebetweenthesurfacesbeingsealed.
decisions. Values stated herein in inch-pound units are to be
3.1.2 breadth, n—temperature range over which peel force
regarded separately and may not be exact equivalents to SI
of a seal is (relatively) constant.
units. Therefore, each system shall be used independently of
3.1.3 burnthrough, n—a state or condition of a heatseal
the other. Combining values from the two systems may result
characterized by melted holes and thermal distortion.
in non-conformance with the standard.
3.1.3.1 Discussion—Burnthrough indicates that the sealing
conditions (time or temperature, or both) were too high to
produce an acceptable seal.
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These test methods are under the jurisdiction of ASTM Committee F02 on
Flexible Barrier Packaging and are the direct responsibility of subcommittee F02.20
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on Physical Properties. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 1, 2012. Published August 2012. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1998. Last previous edition approved in 2004 as F1921-98(2004). DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/F1921-12E01. the ASTM website.
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F1921/F1921M − 12
3.1.4 cohesive failure, n—a failure mode where either or of hot tack. The portion of the curve at higher sealing
bothofthesealedwebsfailsbysplittingapproximatelyparallel temperatures may be affected by failure of the substrate rather
to the seal,
...
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