塑料在包装中的应用

1PlasticinPackagingLesson7第7课塑料在包装中的应用21.Whatelementsareinthemolecule?2.Whatsize(molecularweight)isthemolecule?3.Isthemoleculepolarornon-polar?4.Whatshapeisthemolecule?5.Whatisitsthermalhistory?6.Whatisitsmechanicalhistory?PolymerPropertiesDependOn:3DeformationandThermalHistoryRoomtemperaturedeformationispermanent.PlasticsstretchedataboutTgandcooledslowlyareheatstable.PlasticsstretchedataboutTgandcooledquicklyhave“memory”andwillshrinkifreheated.4PlasticatingExtruderExitportGearreducerVariablespeedmotorFeedthroatFeedhopperHopperthroatCoolingjacketScrewHeaterbandsFig.10.25AdjustableDieLipsExtrusionDieAdjustablePressure(Restrictor)BarExtruderCastFilmandSheetExtrusionFig.10.46Extruder#1Extruder#2Extruder#3Material#1Material#2Material#3Three-LayerCoextrusionFig.10.97ExtrusionCastFilmLineLayoutExtruderExtrusiondieChillrollEdgetrimmerMaterialrollFig.10.58MachineDirectionOrientationRotationx1x3x2X4FromextrudercastingrollsFig.10.89ExtruderCastingRollsAnnealingZoneExtrusionDieTenterClipsCrossDirectionOrientationFig.10.810BubbleBlow-upairinletCoolingairCoolingairPlasticfromextruderDielipadjustingboltsDieBodyDiecoreFrostlineBubbleconstantlypulledupBlown-filmDieCross-SectionFig.10.6Thedieisoftenrotatedtopreventgaugebands11Three-layerExtrusionBlowMoldCut-awayviewmaterial1material2material3filmbubble12ExtruderCirculardieAirringInternalbubblecoolingPlasticfilmbubbleCollapsingframeUpperniprollsSlitterDualrollwinderBlownFilmLineWithSlitterFig.10.713BlownFilmLineShowingDie&Bubble14InjectionMoldingExtrudersFig.10.1015InjectionMoldingMachineExtruderbarrelFeedhopperMoldlocationExtrudersaresizedbytheirclampingcapacity16Three-PlateInjectionMoldFig.10.1217Three-PlateInjectionMold18PartsWithAttachedRunners9Thedistancebetweenthesprueandthegatemustbeexactlythesameforeverycavity19PlasticShrinkageandSinkMarksFig.10.16MostcommonlycanbeseenoppositeclosurethreadsSinkmarksovercupflangesupportribscancausesealingproblemsIntendeddesignShrinkage=fxShrinkage=4fxActualpartproducedSinkmark3x4xX20MoldingUndercutsFig.10.15PedestalplugMainbodyringPedestalringhalvesBodyplugGate21InjectionMoldingUndercuts22Bottle-MakingTerminologyFinish:ThatpartofabottleorjarthatacceptstheclosureParison:AninitialshapethatwillbeexpandedintoabottleorjarinasecondstepPreform:Describestheparisonwhenusinginjectionblow-moldingMoyle:Thepinch-offtrimpiecefromanextrusionblow-moldedbottle23NeckringinsertPinch-offinsertFlashpocketMoldcavityMoldguidepinsCoolingchannelsExtrusionBlowMoldFig.10.2024ExtrusionBlowMoldR1.Neck-ringinsert2.Coolingwaterports3.Cut-offinsert12313225ExtrusionBlowMolding(EBM)Fig.10.1826Injection-BlowMoldingMachine27UntrimmedEBMPPBottleR3.Tailorpinch-offtrim1.Finishtrim2.Handleknock-out12328ParisonExpansion&WallThicknessInitialparisonexpansionisequalinalldirectionswallthicknessExpandingparisonfreezesthemomentittouchesthechilledmoldwallParisoncontinuesstretchingaftertheparisoncenterfreezesParisoncontinuesstretchingaftertheparisoncenterfreezesAsaresult,cornerwallthicknessissignificantlyreducedFigure10.2429Uniform-WalledParisonProgramedParisonFig.10.22ParisonsandBottleWallThickness30Variableopeningcontrolsparison-wallthicknessProgrammableParisonsFig.10.2331ExamplesofCoextrudedBottles1&2Reducedpigmentoninnerlayer3ThreelayerbottlewithU.V.barriercentrallayer123R32Injection-BlowMolding(IBM)Fig.10.23InjectionmoldBlowmoldopenclosedPreformexpandedtoblowmoldPreformcarriedoveroncorepinAir33Injection-BlowMoldingMachineFig.10.27BlowpositionStrippositionPreformsInjectionmoldBlowmoldStripperplateExtruderInjectionpositionrotatingtableCorerod34Injection-BlowMoldingMachine35IBMPreformsandContainerR36Injection-StretchBlowMolding(ISBM)Fig.10.28PreformandcorepinclampedinblowmoldCorepinmovesdown,stretchingpreformPreformblowntocontainershape37ISBMPreformsandSodaBottlesR38PropertiesImposedbyMoldingR39EBMandIBMComparedtoolingonemoldsettwomoldsetsmoldcavitiescommonly2or312andmorepossiblesecondaryoperationstrimandregrindnotrimorregrindfinishtolerancesacceptableprecisionuniquefinishdesignslimitedpossiblehandlewarecommoncomplexthin-wallcontainersyesnocomplexmulti-layersyesdifficultlargecontainersyes(e.g.drums)limitedbasedesignrequirespinch-offnopinch-offFeatureExtrusionB.M.InjectionB.M.Table10.2