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1、Jan10,2007>>AllarticlesFormulatingEthyleneVinylAcetateHotMeltAdhesivesEdwardM.Petrie,MemberofSpecialChemTechnicalExpertTeamIntroductionKeyMaterialPropertiesRequiredforHotMeltAdhesivesFormulationofEVAHotMeltSystemsAdvancesinEVAHotMeltAdhesivesIntroductionHotmeltadhesiv
2、esareincreasinglybecomingpopularbecauseoftheirfastsettingspeed,relativelylowcost(materialsandprocessing),andlowenvironmentalimpact.Hotmeltadhesivesystemsalsohavebroadformulationlatitudesothatamultiplicityofproductscanbeproducedforspecificend-usesandsubstrates.Primaryh
3、otmeltapplicationsarehigh-speedapplicationssuchaspackaging,attachinglabelsandwoodveneer,bookbinding,andtextiles.Hotmeltadhesivescanalsobemanufacturedinvariousformsincludingpellets,slugs,andblocksforbulkapplicationorstickandcontinuousropeformsforheatedgunapplicators.Fi
4、lmsarealsoavailableforhighareaassemblyandcontinuouslaminating.Hotmeltadhesivesareprimarilymadefromthermoplasticpolymersincludingethylenevinylacetate(EVA),blockcopolymerssuchasstyrenebutadienestyrene(SBS)orstyreneisoprenestyrene(SIS),polypropylene(atactic),polyethylene
5、,polyamide,polyester,andpolyurethane.Ofthese,EVAisthemostpopularduetotheirhighversatility.EVAresinsarehighlyflexibleproducts,compatiblewithmanyotherpolymersandadditives,andeasytoprocess.Theyhavehighcohesivestrengthandexcellentadhesiontoawiderangeofsubstrates.EVAcopoly
6、merscanbeusedinsoft,permanentlytackypressuresensitiveadhesivesorintoughrigidhotmeltcompositionsusedforsemi-structuralapplications.Table1identifiesthemajoradvantagesandlimitationsassociatedwithEVAbasedhotmeltadhesives.AdvantagesDisadvantagesBroadformulatinglatitudenece
7、ssaryformanydifferentColdflow(creep)applicationsandadhesiontoawidevarietyofsubstratesAttackedbysomegreases,oils,Quicksetting-nocureorfixturingrequiredandsolventsHighviscosityneededforRetentionofpropertiesatlowtemperaturesmaximumperformanceNowaterorsolventremovalLowequ
8、ipmentandoperatingcostsPressuresensitivesystemscanbeformulatedManyformulationshaveapprovalforfoodcontactRelativelylowcostTab