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Heat Sealable and Easy Peelable Films for food packaging
trays or containers
Nowa days plasticcontainershave been widely u...
The use of plasticcontainershasledtoa requirementforlidswhichcanbothseal the container,inorder
to preventleakage anddrying...
4) Melt-coatingor hot melt-coatingor slot-coating:
Anothertechnique thatallowspolymers,typicallyanEVA or modified-EVA melt...
Technology on heat sealing and peeling multilayer film preparation
MitsubishiTechnology:(Commercial grade is Hostaphan RPS...
Terphane Inc Technology:(commercial Grade is SEALPHANE)
Terphane isalsomaking3 layersealable/peelablefilm film
Composition...
Eastman Chemical Co.Technology:
Heat Man has developedco-extrusiontechnologyforheatsealingfilmforPETtrays by usingthe
foll...
Toray Technology:
Toray has developedhigh beneficial feature of liddingfilms(peelable films);The filmcontain4layers
Base L...
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Sealable and Peelable Technology for Packaging Industry.

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Technology on heat sealing and peeling multilayer film preparation.

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Sealable and Peelable Technology for Packaging Industry.

  1. 1. Heat Sealable and Easy Peelable Films for food packaging trays or containers Nowa days plasticcontainershave been widely usedinpackagingapplications forexample ready- preparedovenablemealswhichare warmedeitherinamicrowave ovenorina conventional oven. Polyesterfilmsare commonlyusedasliddingfilmsforovenable containers.Packagingsystems comprisingarigidheat-stable containerhavingathinflexible thermoplasticfilmsealedontoitare commonlyusedforthe packagingof so-called"ready-meals",thatisfoodproductswhichonlyrequire heatingtobe readyforconsumption.Heatingcanbe carriedout ina microwave or ina conventional oven.Due to the temperaturesinvolvedinthe heatingsteponlyfew materialscanbe usedforthe container,suchas aluminium, polyester-coatedcardboardorpoly(ethyleneterephthalate)(PET). Crystalline PET(CPET) containersare especiallysuitable forthisapplication.Toimprove the heat- sealabilityof these containerswiththe liddingfilmsoftenthe containercomprisesalayerof amorphous PET (APET) as the foodcontact layer. General heatresistantPlasticcontainerisa APET/CPETtray (acomposite material havinganamorphous polyethylene terephthalate layerontopof a crystalline polyethylene terephthalatelayer). To improve the heat-sealabilityof the PETliddingfilmtothe containeraheat-sealablelayerof alower meltingmaterial isusuallyprovidedonthe film.The heat-sealable layermaybe coextrudedwiththe PET base layer,thatis extrudedsimultaneouslythroughasingle die. Low melt Compositionsgenerallyusedforsealantsfor liddingappications Polypropylene Polyethylene Ethylene vinylacetate copolymers(EVA) Ethylene/(meth)acrylate copolymers Amorphouspolyester sealantcomposition canalsocontainfillersoradditivesforachievinganeasypeel characteristic.Many compositionscomprisingpolyolefinsare currentlyusedforpeelableheatsealsinpackagingapplications because of theirgoodprocessability,low cost,andadequate adhesionformanyapplications. PP,PE, EVA compositionsare notsufficientlyrobustforall applications.Forexample,manypackages are refrigeratedorfrozentohelppreservethe product therein,anditisdesirable toretainseal strength incold temperatures.Also,polyolefincompositions(forexample,thosethatcontainEVA) have limited heatresistance thatrestrictstheirabilitytobe processedathightemperatures.
  2. 2. The use of plasticcontainershasledtoa requirementforlidswhichcanbothseal the container,inorder to preventleakage anddryingoutof the packagedcontentsduringstorage,andalsobe easilypeeled fromthe containeronopening.The lidsshouldalsonotstick to the packagedcontentsandshouldbe able to withstandthe heatgeneratedinthe oven. Prior –art technologies forEasy peelable liddingfilms: 1) Off-line process In the filmindustryfirsttime peelablefilmwasdevelopedbyusingoff-line coatingmethod. Organicsolventwasusedinthe off-linecoatingfordissolvingthe polymerin orderto make polymer solution. Thispolymersolutionwasusedascoatinglayeron base filmatany stage of filmprocesssuch as before,duringorbetweenanystretchingprocesses. Remarks/Disadvantage:  Organicsolventscancause stickingor blockingof the filmduringthe windingprocess  Solventsmaybe harmful,hazardousinuse ortoxicto the environment  Filmmade inthisway oftencontainsaresidual amountof solventso maynotsuitable foruse in applicationswheretheycome intocontact withfoodproduct.  The off-line processiscostlyandtime consumed 2) In-line process Sealingfilmproducedbyin-line processwhichavoidsthe use of substantialamountof organic solvent. The filmcomprisesasubstrate andcoatinglayer. The coating layerisapplied asan aqueousdispersionorsolution,usuallywithminoramountof organic solvent. Remarks/Disadvantage:  Limitedtocertaintype of coatingcompositioni.e those that are soluble ordispersable inwater  In addition,thisprocessislimitedinrespectof the achievablelayerthicknessbecausestenter ovenscan remove onlyacertainamountof aqueoussolvent; 3) In line –extrusioncoating process. Example forInline –extrusioncoatingprocess Polyolefinicmaterialontoapolyolefinicsubstrate usinganextrusion-coatingtechnique betweenthe longitudinalandtransverse stretchingoperations("inter-draw"coating) Inter-drawextrusioncoatingof anethylene-vinyl acetate (EVA) copolymerontoa polypropylene substrate toprovide a heat-sealablepeelable film
  3. 3. 4) Melt-coatingor hot melt-coatingor slot-coating: Anothertechnique thatallowspolymers,typicallyanEVA or modified-EVA meltadhesive,tobe applied to a varietyof substratessuchas paperor polymericfilm. Thisprocessusedinthe manufacture of commercially-available pressure-sensitiveadhesivetape In the traditional melt-coatingprocess,the substrate webispressedupagainstthe die bya rollersuch that there isno air gap betweenthe die andsubstrate.The rollerisgenerallyarubber-backingroller whichprovidessufficientback-pressure tothe die toprovide anevencoatinglayer Remarks/disadvantages: The use of a melt-coatingtechnique isrestrictedtopolymerswhichhave asuitablylow viscosityatthe temperature of the coatingoperation.Ingeneral,melt-coatingprocesseshave previouslybeenusedfor applyingpolymericadhesivecompositions,andnotforpolymerswhichcanprovide the requiredheat- seal and peelingpropertiessuitableforfilmsforcontainerlids.Inaddition,melt-coatinghasgenerally onlybeenusedformaterialswhichmustbe coated"off-line"inordertoavoidstickingandhandling problemsduringsubsequentprocessingandwind-up. 5) RecentCo-ExtrusionTechnology Presentmanycompaniesare usingCo-extrusiontechnologytomake multi-layeredheatsealableand peelablefilmsforfoodpackaging applications
  4. 4. Technology on heat sealing and peeling multilayer film preparation MitsubishiTechnology:(Commercial grade is Hostaphan RPSE/RPSM) Mitsubishi ismaking3layeredco-extrudedfilmforsealingapplication(ABCType) CompositionusedinABCtri-layerfilm: Layer A composition a) 20 wt%of polyestercomprising22mol% IPA and 6 wt% Sylysia-430 (SiO2d50 3 micron) b) 80 wt%polyesterpreparedbyusing40mol% azealicacidand 10 mole%IPA (Tgisabout 0 Deg C) Layer B composition 100% homoPET Layer C composition a) 85 wt%homoPET b) 15 wt%of masterbatch of 99% homoPETand 1 wt%of Sylobloc44H d50 2.5 micron http://www.m-petfilm.com/Europe/peelable%20film.htm Sealingtemp:120 to 200 degC SealingPressure:4bar SealingTime:0.5seconds
  5. 5. Terphane Inc Technology:(commercial Grade is SEALPHANE) Terphane isalsomaking3 layersealable/peelablefilm film CompositionusedinABCtri-layerfilm: Layer A composition Blendingof 75 wt% of homoPETand 25 wt%of homoPETcontaining 5000 ppm of silica(2 micron) Layer B composition 65 wt%Virgin PET and35 wt%of filmregrindPET Layer C composition 100 wt%Low meltPET,1 wt%2 micronsilica,1%stearyl erucamideand1 wt%Behenamide SealingTemp:110 to 230 Sealingpressure: 25 Psi SealingTime:2seconds Terphane has developed SEALPHANEheatsealable PETforlidding(peelable/sealable) andpermanent seal applications
  6. 6. Eastman Chemical Co.Technology: Heat Man has developedco-extrusiontechnologyforheatsealingfilmforPETtrays by usingthe followingcomposition: Layer A composition 95 wt%copolyestercontaining31 mol% CHDMand 5 wt%of random ethylene/methyl acrylate/glycidyl methacrylateterpolymer(Lotader AX8900) Layer B composition 100% PET copolymercontaining3.5mol% CHDM SealingTemp:120 -140 degC SealingTime:2- 5 seconds Dupont Technology-1(off-line coating) Duponthas developdheatseal filmsforliddingapplication,Inthisprocessbase filmwascoatedwith polymerof 65 mole %methyl methacrylate,33mole % ethyl acrylate and2 mole % acrylic acidto interfacial layer(ADCOTEX5-183A.) and appliedheatseal layeroninterfacial layer; Base Layer 100 wt%of biaxiallyorientedpolyethyleneterephthalate interfacial layer 95wt% of polymerof 65 mole % methyl methacrylate,33mole % ethyl acrylate and 2 mole % acrylicacid 5 wt%of melamine formaldehyde Heat Seal Layer (control film) a) 50 wt% copolyestercontaining45mol% azealaicacid b) 50 wt% copolyestercontaining45mol% IPA Heat Seal filmpreparation throughin-line process: The Supportlayerwas solutioncoatedwiththe Interface Material inanamountof about0.1 to 0.5 grams Interface Material persquare meterof SupportLayer;thereafterthe interface coatingwas solutioncoatedwiththe copolyestermaterial usedinthe Control inanamountof 1 gram copolyester persquare meter. SealingTemp:120 deg C SealingTime:0.2minutes Peel strengthsinthe range of about50-100 g/inch.
  7. 7. Toray Technology: Toray has developedhigh beneficial feature of liddingfilms(peelable films);The filmcontain4layers Base Layer Polypropylene BarrierLayer Blendof ethylenevinyl alcohol andapolyvinyl alcohol aqueoussolution and crosslinkinganddefoamingagents, Adhesive Layer Polyethylene Heat Seal Layer Ethylene vinylacetate copolymer(EVA copolymer) andblendsof EVA copolymerwithpolyethylene Seal Temperature:140 degC Sealingpressure:30 Psi SealingTime:0.5seconds Presto Products,Incorporated: Thiscompanyhas developed2layersealable films Base Layer (B) PolyesterorcopolyesterLayer Sealinglayer(A) AmorphousCo-polyestercontainingCHDMand /or IPA SealingTemp:120 to 232 Sealingpressure:40 Psi SealingTime:0.5seconds Dupont Technology-2(co-extrusion) –Commercial Grade-Malor-OL Heat-sealable,coextrudedcomposite polymericfilm wdevelopedbyDupont Substrate copolyesterof azelaicacid/terephthalicacid/ethylene glycol (6/94/100) Heat-sealable layer copolyesterof azelaicacid/terephthalicacid/ethylene glycol (45/55/100) and1.5% by weight(relativetothe total compositionof the layer) of anN,N'-ethylene bis(oleamide) wax (EBO;obtainedasCrodamide EBOfromCroda),and3% by weight (relative tothe total compositionof the layer) of silicafillerparticleswithan average particle size of 1 .mu.m. SealingTemp:110 to 150 Sealingpressure:1N/mm2 Sealingtime: 0.5 sec

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