ASTM F1921-12

Standard Test Methods for Hot Seal Strength (Hot Tack) of Thermoplastic Polymers and Blends Comprising the Sealing Surfaces of Flexible Webs

SIGNIFICANCE AND USE
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 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 of regulatory limitations prior to use. The operator of the equipment is to be aware of pinch points as the seal jaws come together to make a seal, hot surfaces of the jaws, and sharp instruments used to cut specimens. It is recommended that the operator review safety precautions from the equipment supplier.

General Information

• Status: Historical
• Publication Date: 30-Jun-2012
• ICS: 83.120 - Reinforced plastics
• Technical Committee: F02 - Primary Barrier Packaging
• Drafting Committee: F02.20 - Physical Properties

Relations

• Replaces: ASTM F1921-98(2004) - Standard Test Method for Hot Seal Strength (Hot Tack) of Thermoplastic Polymers and Blends Comprising the Sealing Surfaces of Flexible Webs
• Effective Date: 01-Jul-2012
• Referred By: ASTM F2029-16(2021) - Standard Practices for Making Laboratory Heat Seals for Determination of Heat Sealability of Flexible Barrier Materials as Measured by Seal Strength
• Effective Date: 01-Jul-2012
• Referred By: ASTM F2097-20 - Standard Guide for Design and Evaluation of Primary Flexible Packaging for Medical Products
• Effective Date: 01-Jul-2012

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: F1921 − 12
StandardTest Methods for
Hot Seal Strength (Hot Tack) of Thermoplastic Polymers and
1
Blends Comprising the Sealing Surfaces of Flexible Webs
This standard is issued under the fixed designation F1921; 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 priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. The operator of the
1.1 These two test methods cover laboratory measurement
equipment is to be aware of pinch points as the seal jaws come
of the strength of heatseals formed between thermoplastic
together to make a seal, hot surfaces of the jaws, and sharp
surfaces of flexible webs, immediately after a seal has been
instruments used to cut specimens. It is recommended that the
made and before it cools to ambient temperature (hot tack
operator review safety precautions from the equipment sup-
strength).
plier.
1.2 These test methods are restricted to instrumented hot
tack testing, requiring a testing machine that automatically
2. Referenced Documents
heatseals a specimen and immediately determines strength of
2
2.1 ASTM Standards:
thehotsealatapreciselymeasuredtimeafterconclusionofthe
D882 Test Method for Tensile Properties of Thin Plastic
sealing cycle. An additional prerequisite is that the operator
Sheeting
shall have no influence on the test after the sealing sequence
E171 Practice for Conditioning and Testing Flexible Barrier
has begun. These test methods do not cover non-instrumented
Packaging
manual procedures employing springs, levers, pulleys and
E691 Practice for Conducting an Interlaboratory Study to
weights, where test results can be influenced by operator
Determine the Precision of a Test Method
technique.
F88 Test Method for Seal Strength of Flexible Barrier
1.3 Two variations of the instrumented hot tack test are
Materials
described in these test methods, differing primarily in two
F2029 Practices for Making Heatseals for Determination of
respects: (a) rate of grip separation during testing of the sealed
Heatsealability of Flexible Webs as Measured by Seal
specimen, and (b) whether the testing machine generates the
Strength
cooling curve of the material under test, or instead makes a
measurement of the maximum force observed following a set
3. Terminology
delay time. Both test methods may be used to test all materials
3.1 Definitions:
withinthescopeofthesetestmethodsandwithintherangeand
3.1.1 adhesive failure, n—a failure mode in which the seal
capacity of the machine employed. They are described in
failsattheoriginalinterfacebetweenthesurfacesbeingsealed.
Section 4.
3.1.2 breadth, n—temperature range over which peel force
1.4 SI units are preferred and shall be used in referee
of a seal is (relatively) constant.
decisions. Values stated herein in inch-pound units are to be
3.1.3 burnthrough, n—a state or condition of a heatseal
regarded separately and may not be exact equivalents to SI
characterized by melted holes and thermal distortion.
units. Therefore, each system shall be used independently of
3.1.3.1 Discussion—Burnthrough indicates that the sealing
the other. Combining values from the two systems may result
conditions (time or temperature, or both) were too high to
in non-conformance with the standard.
produce an acceptable seal.
1.5 This standard does not purport to address all of the
3.1.4 cohesive failure, n—a failure mode where either or
safety concerns, if any, associated with its use. It is the
bothofthesealedwebsfailsbysplittingapproximatelyparallel
responsibility of the user of this standard to establish appro-
to the seal, and the seal itself remains intact.
1
These test methods are under the jurisdiction of ASTM Committee F02 on
Flexible Barrier Packaging and are the direct responsibility of subcommittee F02.20
2
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 [e-mail]. 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/F1921-12. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
F1921 − 12
3.1.4.1 Discussion—Refer to Fig. 1. The term may be 3.1.13 seal initiation temperature, n—sealingtemperatureat
defined somewhat differently when applied to sealin
...

This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:F1921–98(Reapproved2004) Designation:F1921–12
Standard Test Methods for
Hot Seal Strength (Hot Tack) of Thermoplastic Polymers and
1
Blends Comprising the Sealing Surfaces of Flexible Webs
This standard is issued under the fixed designation F1921; 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
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 Twovariationsoftheinstrumentedhottacktestaredescribedinthesetestmethods,differingprimarilyintworespects:((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.
1.4SI units are preferred and shall be used in referee decisions.
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 of regulatory
limitations prior to use. The operator of the equipment is to be aware of pinch points as the seal jaws come together to make a
seal, hot surfaces of the jaws, and sharp instruments used to cut specimens. It is recommended that the operator review safety
precautions from the equipment supplier.
2. Referenced Documents
2
2.1 ASTM Standards:
D882 Test Method for Tensile Properties of Thin Plastic Sheeting
E171 Practice for Conditioning and Testing Flexible Barrier Packaging Practice for Conditioning and Testing Flexible Barrier
Packaging
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
F88 Test Method for Seal Strength of Flexible Barrier Materials
F2029 Practices for Making Heatseals for Determination of Heatsealability of Flexible Webs as Measured by Seal Strength
3. Terminology
3.1 Definitions:
3.1.1 adhesive failure, n—a failure mode in which the seal fails at the original interface between the surfaces being sealed.
3.1.2 breadth, n—temperature range over which peel force of a seal is (relatively) constant.
3.1.3 burnthrough, n—a state or condition of a heatseal characterized by melted holes and thermal distortion.
3.1.2.1
1
These test methods are under the jurisdiction ofASTM Committee F02 on Flexible Barrier MaterialsPackaging and are the direct responsibility of subcommittee F02.20
on Physical Properties.
Current edition approved Oct. 10, 1998. Published February 1999. DOI: 10.1520/F1921-98R04.
Current edition approved July 1, 2012. Published August 2012. Originally approved in 1998. Last previous edition approved in 2004 as F1921-98(2004). DOI:
10.1520/F1921-12.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-295
...