包装盒专业英语3.ppt

包装盒专业英语3.ppt

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UNITTWOPACKAGINGMATERIALSANDCONTAINER第二单元第二单元包装材料和容器包装材料和容器Lesson3PaperandPaperboard第第3课课纸与纸板纸与纸板IntroductionDefinitionofpaper:

Paperisdefinedasamattedorfeltedsheetusuallycomposedofplantfiber.Paperhasbeencommerciallymadefromsuchfibersourcesasrags（linen）,bagasse（sugarcane）,cotton,andstraw.Modernpaperismadealmostexclusivelyfromcellulosefiberderivedfromwood.Althoughtheword“paper”isderivedfromtheEgyptianterm,“papyrus”wasnotatruepaperinthemodernsense.-InventionofpaperTheinventionofpaperbyblendingcellulosefibersdidntoccuruntilthebeginningofthesecondcenturyA.D.IntroductionTsaiLun,amemberofthecourtofthelaterHanDynasty,isgenerallycreditedwithdevelopingthefirstrealpapermakingprocessin105A.D.The“Fourdriniermachine”wasthefirstonthemarketandproducedahomogenous（single-ply）sheetofboxboardinvariousthicknesses.Itwassoonjoinedbythe“Cylindermachine”whichformedamulti-layered（multi-ply）typeofpaperboard.ThesemachineswerefirstinstalledintheUnitedStatesaround1830.IntroductionPaperandpaperboardPaperboard,boxboard,cardboard,andcartonboardarealltermsusedtodescribeheavierpaperstock.TheInternationalOrganizationforStandardization（ISO）statesthatmaterialweighingmorethan250gramspersquaremetre（511bper1,000sq.ft.）shallbeknownaspaperboard.U.S.practicecallsmaterialthatismorethan300（0.012in.）thickpaperboard.RepresentativePapermakingMachinesFourdrinierMachinesFourdriniermachines（Figure3.1）pumpfurnishfromaheadboxdirectlyontoamovingwirescreenthroughwhichthewateriscontinuouslydrained.Fourdriniermachinesmayhaveasecondheadbox（Figure3.2）situateddownstreamofthefirstheadboxtoaddfurtherquantitiesoffurnishontothepartiallydewateredinitiallay-down.RepresentativePapermakingMachinesFigure3.1Furnishpoursoutoftheheadboxofafourdriniermachineandontoanendlesswireorscreenwhereexcesswatercanbedrained.ThefibersremaintrappedonthescreenRepresentativePapermakingMachinesFigure3.2PaperisdewateredatthewetendofafourdriniermachineRepresentativePapermakingMachinesCylinderMachinesAcylindermachine（Figure3.3）rotatesascreendruminavatoffurnish.（Thepaperissometimescalledvatpaper.）Asthewaterpoursthroughthescreen,fiberaccumulatesontheoutsideofthescreen.Thisthinlayerofmattedfiberistransferredontoamovingfeltbeltthatpassessequentiallyoverfurtherrotatingcylinders,eachofwhichdepositsanotherfiberlayer.RepresentativePapermakingMachinesFigure3.3Asinglecylinderstationonacylinder-typemachineRepresentativePapermakingMachinesCylindermachinesdewaterfurnishatthecylinderandpasteathinlayeroffiberagainstthefelt.（Figure3.4.）Figure3.4AcylindermachinewithsixcylindersatwhichapaperlayercanbeformedRepresentativePapermakingMachinesThefibersofsubsequentlayersdonotintermingle,andthereforethebondbetweenthelayersisweak.Thedryendissimilartothatofthefourdriniermachine.Cylindermachinesdonothavethefourdriniermachineslimitationonthenumberofstations,andsix-orseven-stationmachinesarecommon.Higher-caliperboardsforfoldingandsetupcartonsareusuallycylinderboards.Generally,papersaremadeonfourdrinierortwin-wireformers,whereasheavierpaperboardproductsaremadeoncylinder-typemachines.Extremelyheavyboardsaremadebylaminatingseveralthinnersheets.Atypicalcylinderboardconstruction（Figure3.5）:

RepresentativePapermakingMachinesFigure3.5Cylinderboardsaremultiplyboards.AnadvantageisthatthepliescanallbedifferentRepresentativePapermakingMachinesTwin-WireMachinesVertiformersandtwin-wireformers（Figure3.6）injectthefurnishbetweentwomovingwirescreens.Theadvantageisthatdewateringtakesplaceonbothsidesofthepaperandisthereforefast.Thesemachinescanproducesingleandmulti-plysheetswithidenticalformationatbothfaces.MachineDirectionandCrossDirectionDepositingafiber-and-waterslurryontoamovingwirebelttendstoalignfibersinthedirectionoftravel,knownasthemachinedirection（MD）.Thedirectionacrosstheapermakingmachineandacrossthefiberalignmentisthecrossdirection（CD）（Figure3.7）.Becauseofthisfiberalignment,paperisananisotropicmaterial;measuredpropertiesdifferdependingonthedirectioninwhichthepropertyismeasured.RepresentativePapermakingMachinesFigure3.6Watercanbesimultaneouslyremovedfrombothsidesofthepaperonatwin-wirepaperformerRepresentativePapermakingMachinesFigure3.7FibersinamanufacturedpapersheettendtoalignthemselvesinthemachinedirectionRepresentativePapermakingMachinesFigure3.8showstherelationshipoftear,stiffness,andfoldendurancetomachinedirection.Paperspecificationsheetsnormallyshowphysicalvaluesmeasuredin