包装材料专业英语

1、第5、6讲Unit3PackagingMaterialsandContainers(第三单元包装材料和容器)Lesson1PaperandPaperboard(第1课纸与纸板)(概述，典型造纸机，纸板的加工方向与横向，表面处理与涂覆，纸特性，纸/纸板等级，纸盒)Introduction(概述)Definitionofpaper:paperisdefinedasamattedorfeltedsheetusuallycomposedofplantfiber.Paperhasbeencommerciallymadefromsuchfibersourcesasrags(linen),bagasse(s

2、ugarcane),cotton,andstraw.Modernpaperismadealmostexclusivelyfromcellulosefiberderivedfromwood.Althoughtheword“paper”isderivedfromtheEgyptianterm,“papyrus”wasnotatruepaperinthemodernsense.Inventionofpaper:theinventionofpaperbyblendingcellulosefibersdidntoccuruntilthebeginningofthesecondcenturyA.D.Tsa

3、iLun,amemberofthecourtofthelaterHanDynasty,isgenerallycreditedwithdevelopingthefirstrealpapermakingprocessin105A.D.The“Fourdriniermachine”wasthefirstonthemarketandproducedahomogenous(single-ply)sheetofboxboardinvariousthicknesses.Itwassoonjoinedbythe“Cylindermachine”whichformedamulti-layered(multi-p

4、ly)typeofpaperboard.ThesemachineswerefirstinstalledintheUnitedStatesaround1830.Paperboard,boxboard,cardboard,andcartonboardarealltermsusedtodescribeheavierpaperstock.TheInternationalOrganizationforStandardization(ISO)statesthatmaterialweighingmorethan250gramspersquaremetre(511bper1,000sq.ft.)shallbe

5、knownaspaperboard.U.S.practicecallsmaterialthatismorethan0.3mm(0.012in.)thickpaperboard.RepresentativePapermakingMachines(典型造纸机)(1)FourdrinierMachinesFourdriniermachines(Figure3.1)pumpfurnishfromaheadboxdirectlyontoamovingwirescreenthroughwhichthewateriscontinuouslydrained.Fourdriniermachinesmayhave

6、asecondheadbox(Figure3.2)situateddownstreamofthefirstheadboxtoaddfurtherquantitiesoffurnishontothepartiallydewateredinitiallay-down.Slice19IHeadrollTablerolfsWirejrnishsadboxPufplayerFigure3.1Furnishpoursoutoftheheadboxofafourdriniermachineandontoanendlesswireorscreenwhereexcesswatercanbedrained.The

7、fibersremaintrappedonthescreenFigure3.2Paperisdewateredatthewetendofafourdriniermachine(2)CylinderMachinesAcylindermachine(Figure3.3)rotatesascreendruminavatoffurnish(Thepaperissometimescalledvatpaper).Asthewaterpoursthroughthescreen,fiberaccumulatesontheoutsideofthescreen.Thisthinlayerofmattedfiber

8、istransferredontoamovingfeltbeltthatpassessequentiallyoverfurtherrotatingcylinders,eachofwhichdepositsanotherfiberlayer.Figure3.3Asinglecylinderstationonacylinder-typemachineCylindermachinesdewaterfurnishatthecylinderandpasteathinlayeroffiberagainstthefelt(Figure3.4).Thefibersofsubsequentlayersdonot

9、intermingle,andthereforethebondbetweenthelayersisweak.Thedryendissimilartothatofthefourdriniermachine.FeltCylinderstations0Couchrollsq_j9o0swszersFigure3.4AcylindermachinewithsixcylindersatwhichapaperlayercanbeformedCylindermachinesdonothavethefourdriniermachineslimitationonthenumberofstations,andsi

10、x-orseven-stationmachinesarecommon.Higher-caliperboardsforfoldingandsetupcartonsareusuallycylinderboards.Anadvantageofcylindermachinesisthatlow-qualityfibercanbeusedtofillorbulkthemiddleofaboard,whilehigherqualitybleachedfiberscanbeusedononeorbothliners.Cylinderboardhasdefinitelayers,orplies,andindi

11、vidualpliescanoftenbeeasilyseparated.Generally,papersaremadeonfourdrinierortwin-wireformers,whereasheavierpaperboardproductsaremadeoncylinder-typemachines.Extremelyheavyboardsaremadebylaminatingseveralthinnersheets.Atypicalcylinderboardconstruction(Figure3.5)mayhaveatoplinercomposedofgood-qualityble

12、achedpulpwithsomeshortfibers,possiblysizedandclaycoatedtoproduceasmooth,attractiveprintingsurface.Theunderlinermayalsobecomposedtoagood-qualitystock,possiblybleachedtoprovideasmooth,opaquebaseforthetopliner.Fillerpliesusethemosteconomicalrecycledpulps,sincetheyhavelittleimpactonpropertiessuchasstiff

13、ness.Thebottomlinerisabetterqualitypulptoaddstiffness.Ifappearanceisnotafactor,thelinermaybegood-qualityrecyclepulp.Ifappearanceiscriticalorifthepaperboardwillbeprintedonbothsides,thebottomlinerwillalsobebleachedstock.13*ToplinerUnderliner2二IFillerBottomunderlinerBottomlinerFigure3.5Cylinderboardsar

14、emultiplyboards.AnadvantageisthatthepliescanallbedifferentTwin-WireMachinesVertiformersandtwin-wireformers(Figure3.6)injectthefurnishbetweentwomovingwirescreens.Theadvantageisthatdewateringtakesplaceonbothsidesofthepaperandisthereforefast.Thesemachinescanproducesingleandmulti-plysheetswithidenticalf

15、ormationatbothfaces.WireFurnishSliceWireTodryerWetpaperlayerWalerdeflectorsFigure3.6Watercanbesimultaneouslyremovedfrombothsidesofthepaperonatwin-wirepaperformerMachineDirectionandCrossDirection(纸板的加工方向与横向)Depositingafiber-and-waterslurryontoamovingwirebelttendstoalignfibersinthedirectionoftravel,kn

16、ownasthemachinedirection(MD).Thedirectionacrossthepapermakingmachineandacrossthefiberalignmentisthecrossdirection(CD)(Figure3.7).Becauseofthisfiberalignment,paperisananisotropicmaterial;measuredpropertiesdifferdependingonthedirectioninwhichthepropertyismeasured.Figure3.7Fibersinamanufacturedpapershe

17、ettendtoalignthemselvesinthemachinedirectionFigure3.8showstherelationshipoftear,stiffness,andfoldendurancetomachinedirection.Paperspecificationsheetsnormallyshowphysicalvaluesmeasuredinbothdirections.Packagedesignersneedtobeawareofpapersdirectionality.aMD/FoldendjrancsIsgreateracrossMDthanalongmd.Te

18、afsesierafongMDthanacrossMD,StlffrSSSiS0reaterWhenpaperis圖吨諾呃畑thanwheniiisbentalongWD.Figure3.8TherelationshipbetweenMDandtear,stiffness,andfoldendurancepropertiesCylindermachinestendtoalignfibersmorethanfourdriniermachines.TensilestrengthratiosinMDandCDforatypicalfourdrinierboardareabout2:1,whereas

19、foracylinderboardtheratiomightbe4:1orhigher,meaningthattheMDtensilestrengthisfourtimesgreaterthantheCDtensilestrength.Thegreaterthedegreeoffiberalignment,thegreaterthedifferenceinagivenpropertywhenmeasuredinMDandCD.Theratioofapropertyinthetwodirectionsisoftenusedasagaugeoffiberalignment.SurfaceorDry

20、-End,TreatmentsandCoatings(表面处理与涂覆)Afterthepaperisformedanddried,itisusuallypassedbetweenmultiplesetsofheavyrolls(Figure3.9).Thiscalenderingoperationhasmanyvariations,buttheprimeobjectiveistoironandsmoothoutthesurfaceofthepaperstocktomakeitmoresuitableforprinting.Calenderingalsocompressesthepapershe

21、et,givingadenserproductandaglossiersurface.Starchisatypicalsurfacesizingusedtofillsurfacevoidsandreduceliquidpenetrationrate.Thepapersurfacemaybedampenedtohelpinsmoothingit.Tomeetthehighestopacity,gloss,brightness,andprinting-detailrequirements,papersarecoatedwithpigmentssuchasclay,calciumcarbonate,

22、andtitaniumdioxide.Coatedpapersareusuallycalledclay-coatedregardlessoftheactualformulation.Coatedpapersarecalenderedtomaintainahigh-quality,smoothsurface.Inaddition,highlysizedandclay-coatedboardscanbedifficulttobondwithwater-basedadhesivebecauseofpoorliquidpenetrationandtheinabilityoftheadhesivetob

23、ondtotheunderlyingfibers.Wherenecessary,coatedboardsshouldhaveperforationsintheadhesive-bondareassothatadhesivecanpenetratetothebodyofthepaper.PaperCharacterization(纸特性)CaliperandWeightIninch/poundunits:Caliperisexpressedinthousandthsofaninchorinpoints.Onethousandthofaninchis1point.(Forexample,a0.02

24、0-in.boardwouldbe20points.)Containerboardforthecorrugatedboardindustryandmostpaperboardsarespecifiedbytheweightinpoundsper1,000sq.ft.,thebasisweight.Finepaperscanbespecifiedbytheweightinpoundsperream.Areamis500sheets,buttheactualsheetsizecanvarydependingontheproduct.Inmostinstancesareamistakentobe3,

25、000sq.ft.Inmetricunits:Caliperisexpressedinmormicrometres(|Jm).Papermass/unitarearelationshipisreportedasgrammage,definedasbeingthemass(weight)ofpaperin1squaremetre(m2).Themetricconversionfactorsarelbs./l,000sq.ft.=4.88grams/m20.001inch=25.4(usuallyroundedto25pm)1mm=1,000pmBrightnessBrightnessisamea

26、sureofthetotalreflectanceofwhitelight.Valuesareexpressedonascaleof1to100,with100beingthebrightnessofpuremagnesiumoxide.Mostqualitygradeshavereflectancevaluesinthemid-80s.Thebrightertheboard,themorebrilliantthegraphicpossibilities.PaperandMoistureContentPaperishygroscopicandabsorbsandlosesmoistureacc

27、ordingtotheambientrelativehumidity(R.H.)andtemperature.Paperat20%R.H.willcontainabout4%moisture,whileat80%R.H.,itwillcontainabout15%moisture.Thephysicalpropertiesofpapervarydramaticallywithmoisturecontent,andinsomeapplicationsthemoisturecontentofthepaperduringprocessingmustbecontrolled.Becausephysic

28、alcharacterizationvaluesdependonmoisturecontent,allpapertestingmustbedoneatapreciselycontrolledtemperatureandhumidity.Internationally,thestandardconditionsarespecifiedas23Cand50%R.H.Paperishygroexpansive:whenitabsorbsmoisture,itexpands;whenitdriesout,itshrinks.Between0and90%R.H.,thedimensionscanchan

29、ge0.8%intheMDand1.6%intheCD.Wheneverapapersheetislaminatedtoorcoatedwithamaterialthatisnotaffectedbymoisture(forexample,plasticfilm,aluminumfoil,orheavyprintorvarnish),thereisthepotentialforcurlingwhenthehumiditychanges.Ifthepapergainsmoistureandexpandswhilethesurfacinglaminateorcoatingremainsthesam

30、e,thepaperwillcurltowardthesurfacingmaterial.Whenthepaperlosesmoisture,itwillshrinkandcurlawayfromthesurfacingmaterial(Figure3.10).at40%R.H.at20%R.H.at80%R.H.Figure3.10PapershygroexpansivenaturecancauseunwantedcurlingwhenpaperisbondedtoanenvironmentallystablesurfaceViscoelasticityPaperismoreorlessvi

31、scoelastic,dependingontherateatwhichloadisapplied.Simplyput,thefasteraloadisapplied,thegreatertheapparentstrength.Overlongloadingperiods,paperfibersmoveanddistortorcreep.PaperTypes(纸类型)NewsprintandRelatedGradesBookPapersCommercialPapersGreaseproofPapersNaturalKraftPaperBleachedKraftsandSulfitesTissu

32、ePaperLabelPaperPouchPapersContainerboards(linerboardandmedium)PaperboardGrades(纸板类型)Chipboard,Cardboard,NewsboardBendingChipboardLinedChipboardSingleWhite-Lined(SWL)PaperboardClay-CoatedNewsback(CCNB)DoubleWhite-Lined(DWL)PaperboardSolidBleachedSulfate(SBS)FoodBoardSolidUnbleachedSulfate(SUS)Paperb

33、oardCartons(纸盒)Paperboardprovidesaversatileandeconomicalmaterialnotreadilymatchedbyotherpackagingmediums.Onesignificantadvantageisthelowtoolingcostcomparedwiththatformaterialssuchasplastics.Effectivepaperboardpackagedesignisbasedpartlyonknowledgeofpaperandproductpropertiesandpartlyoncraftsmanshipand

34、art.Paperboardpackagingcanbeconsideredinanumberofcategories.FoldingCartonsFoldingcartonsarebyfarthelargestandmostimportantgroupinpaperboardpackaging.Foldingcartonsaremadeasflatblanksoraspregluedformsthatcanbeflattenedforshipping.Theycanbemadeeconomicallyonhigh-speedproductionmachinery.Themajorityoff

35、oldingcartondesignscanbeclassifiedasfallingintoeitherthetube-style(Figure3.11)orthetray-styledesignfamilies(Figure3.12).Figure3.11Agable-topcartonblankandanerectedgable-topcartonMD匚FrontpanelooFrontcoverpanelRearpanelBottompanelCoverpanelFigure3.12Asix-corneredBrightwoodtray,flatandassembledThegable

36、-topcontainer(Figure3.11)isbasicallyatube-stylecartonthathasfoundmanyapplications,particularlyfordairyproductsandfruitjuices.Theheavilysizedandpolyethylene-coatedboardiserectedandheat-sealedatthepointoffill.CombiblocandTetraPakaresimilar-appearingproprietarycartonsmadefromcomplexpaper/foil/polylaminates.Aprincipalapplicationisforasepticbever