包装技术基础(双语教学)3

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1、UNITTWOPACKAGINGMATERIALSANDCONTAINER第二单元包装材料和容器Lesson3PaperandPaperboard第3课纸与纸板IntroductionDefinitionofpaper:·Paperisdefinedasamattedorfeltedsheetusuallycomposedofplantfiber.Paperhasbeencommerciallymadefromsuchfibersourcesasrags(linen),bagasse(sugarcane),cotton,andstraw.Modern

2、paperismadealmostexclusivelyfromcellulosefiberderivedfromwood.·Althoughtheword“paper”isderivedfromtheEgyptianterm,“papyrus”wasnotatruepaperinthemodernsense.-Inventionofpaper·Theinventionofpaperbyblendingcellulosefibersdidn’toccuruntilthebeginningofthesecondcenturyA.D.Introducti

3、onTs’aiLun,amemberofthecourtofthelaterHanDynasty,isgenerallycreditedwithdevelopingthefirstrealpapermakingprocessin105A.D.·The“Fourdriniermachine”wasthefirstonthemarketandproducedahomogenous(single-ply)sheetofboxboardinvariousthicknesses.Itwassoonjoinedbythe“Cylindermachine”whic

4、hformedamulti-layered(multi-ply)typeofpaperboard.ThesemachineswerefirstinstalledintheUnitedStatesaround1830.IntroductionPaperandpaperboard·Paperboard,boxboard,cardboard,andcartonboardarealltermsusedtodescribeheavierpaperstock.·TheInternationalOrganizationforStandardization(ISO)

5、statesthatmaterialweighingmorethan250gramspersquaremetre(511bper1,000sq.ft.)shallbeknownaspaperboard.U.S.practicecallsmaterialthatismorethan300(0.012in.)thickpaperboard.RepresentativePapermakingMachinesFourdrinierMachinesFourdriniermachines(Figure3.1)pumpfurnishfromaheadboxdire

6、ctlyontoamovingwirescreenthroughwhichthewateriscontinuouslydrained.Fourdriniermachinesmayhaveasecondheadbox(Figure3.2)situateddownstreamofthefirstheadboxtoaddfurtherquantitiesoffurnishontothepartiallydewateredinitiallay-down.RepresentativePapermakingMachinesFigure3.1Furnishpour

7、soutoftheheadboxofafourdriniermachineandontoanendlesswireorscreenwhereexcesswatercanbedrained.ThefibersremaintrappedonthescreenRepresentativePapermakingMachinesFigure3.2PaperisdewateredatthewetendofafourdriniermachineRepresentativePapermakingMachinesCylinderMachinesAcylindermac

8、hine(Figure3.3)rotatesascreendruminavatoffurnish.(Thep