ASTM_F_2029_-_08.pdf

Designation:F202908Standard Practices forMaking Heatseals for Determination of Heatsealability ofFlexible Webs as Measured by Seal Strength1This standard is issued under the fixed designation F2029;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 These practices cover laboratory preparation of heat-seals and the treatment and evaluation of heatseal strength datafor the purpose of determining heatsealability of flexiblebarrier materials.It does not cover the required validationprocedure for the materials and production equipment.1.2 Testing strength or other properties of the heatsealsformed by these practices is not included in this standard.Referto Test Method F88 for testing heatseal strength.1.3 The practices of this standard are restricted to sealingwith a machine employing hot-bar jaw(s).Impulse,high-frequency,and ultrasonic heating methods are not included.1.4 These practices apply primarily to webs intended to beused on commercial machines employing reciprocating sealingjaws,such as most form-fill-seal packaging machines,platenheatsealers,and so forth.Conditions of dwell time and sealingpressure on machines of this type typically are different fromthose on rotary machines.1.5 The procedure of this practice with respect to choice ofheatsealing conditions apply to ultimate seal strength or hottack measurement.1.6 Seals may be made between webs of the same ordissimilar materials.The individual webs may be homoge-neous in structure or multilayered(coextruded,coated,laminated,and so forth).1.7 Strength of the heatseal as measured by Test MethodF88 is the criterion for judging heatsealability employed inthese practices.1.8 Determination of heatsealability as judged by sealcontinuity,typically measured by air-leak,dye penetration,visual examination,microorganism penetration,or othertechniques,are not covered by these practices.1.9 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.10 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility 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 Documents2.1 ASTM Standards:2F88 Test Method for Seal Strength of Flexible BarrierMaterialsF1921 Test Methods for Hot Seal Strength(Hot Tack)ofThermoplastic Polymers and Blends Comprising the Seal-ing Surfaces of Flexible WebsD4332 Practice for Conditioning Containers,Packages,orPackaging Components for Testing3.Terminology3.1 Definitions:3.1.1 dwell time,nthe time interval when the sealing jawsare in contact with,and exerting pressure on,the material beingsealed.3.1.2 heatseal curve,na plot of measured seal strengthversus sealing temperature when dwell and pressure are fixed.3.1.2.1 DiscussionThis is the basic curve for comparingsealability of materials.It plots the force required to extend asealed test strip to failure,as a function of sealing temperaturewhen dwell and pressure are fixed.The portion of the curve athigher sealing temperatures may be affected by failure of thesubstrate and may not be an accurate representation of sealstrength.3.1.3 heatseal strength,nforce required to peel the sealapart,per unit width of seal.3.1.3.1 DiscussionIn many tests of seal strength,it is notthe seal that fails,it is the substrate or a layer.In those tests,the1These practices are under the jurisdiction ofASTM Committee F02 on FlexibleBarrier Packaging and are the direct responsibility of Subcommittee F02.20 onPhysical Properties.Current edition approved April 1,2008.Published May 2008.Originallyapproved in 2000.Last previous edition approved in 2000 as F2029 00.DOI:10.1520/F2029-08.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 true heatseal strength may be somewhat higher than themeasured force that caused the specimen to fail.Some mate-rials are intentionally designed to fail in a layer not at the sealinterface in order to gain other attributes such as transferappearance.In this case,this failure is the desired outcome.Homogeneous materials with fusion seals,for example,com-monly break along a line immediately adjacent to the seal,while the seal itself remains intact.3.1.4 heatsealability,nthe property of thermoplastic poly-mers and blends,when comprising a surface of a flexible web,that defines how well the material bonds to itself or a diss