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页数:36页
时间:2018-10-21
《包装技术基础(双语教学)3》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
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
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