PaperPaper andand BoardBoard ManufactureManufacture andand PropertiesProperties WorkshopWorkshop CharlesCharles P.P. KlassKlass KlassKlass AssociatesAssociates Inc.Inc. RedingtonRedington Beach,Beach, FLFL SummarySummary ofof WorkshopWorkshop z OverviewOverview andand terminologyterminology ofof paperpaper andand boardboard gradesgrades thatthat areare extrusionextrusion coatedcoated z PropertiesProperties ofof paperpaper andand boardboard usedused forfor extrusionextrusion coatingcoating z PaperPaper andand boardboard manufacturingmanufacturing variablesvariables thatthat impactimpact extrusionextrusion coatingcoating z TrendsTrends andand developmentsdevelopments z GeneralGeneral groupgroup discussiondiscussion ExtrusionExtrusion CoatedCoated GradesGrades z ExtrusionExtrusion coatingcoating isis appliedapplied toto aa widewide varietyvariety ofof paperpaper andand boardboard gradesgrades dependingdepending onon thethe propertiesproperties soughtsought z ExtrusionExtrusion coating/laminationcoating/lamination cancan bebe usedused toto bondbond foilfoil toto paperpaper oror paperboardpaperboard forfor enhancedenhanced barrierbarrier propertiesproperties ExtrusionExtrusion CoatedCoated GradesGrades Substrate Property Sought End Uses Bag and wrapping MVTR, OGR, QSR, bakery, paper liquid resistance carry-out, multiwall sacks Bleached board Liquid resistance Cups, milk cartons Linerboard MVTR, OGR, Frozen food & liquid resistance, other packaging release VariabilityVariability ofof PaperPaper z PaperPaper isis notnot aa homogeneoushomogeneous material.material. z VariesVaries inin thethe machinemachine directiondirection (MD),(MD), crosscross-- directiondirection (CD),(CD), ZZ--direction,direction, andand overover time.time. z ItIt isis alsoalso reactivereactive toto changeschanges inin itsits environment.environment. ShrinksShrinks andand expandsexpands andand usuallyusually notnot uniformly.uniformly. z ItsIts structurestructure dependsdepends onon thethe processprocess thatthat producedproduced itit andand eveneven thethe locationlocation acrossacross thethe widthwidth ofof thethe paperpaper machine.machine. VariabilityVariability ofof PaperPaper ComponentsComponents ofof WoodWood z CelluloseCellulose –– 45%45% Wood Tissue z LigninLignin –– 25%25% z HemicellulosesHemicelluloses –– 25%25% z ExtractivesExtractives –– 5%5% Cambium Inner Bark CelluloseCellulose (C(C66HH1010OO55))nn FiberFiber StructureStructure PAPRICAN FiberFiber StructureStructure Lumen S3 Layer Lignin Lignin S2 Layer Primary wall S1 Layer Middle lamella FiberFiber StructureStructure z LikeLike aa drinkingdrinking strawstraw z 1/321/32”” (0.75mm)(0.75mm) toto 1/41/4”” (6mm)(6mm) longlong z LengthLength toto widthwidth ratioratio ofof 5050 toto 140140 FiberFiber StructureStructure FiberFiber StructureStructure Pine sheet Eucalyptus sheet FiberFiber StructureStructure z SoftwoodsSoftwoods forfor strengthstrength andand runnabilityrunnability z HardwoodsHardwoods forfor uniformity,uniformity, smoothness,smoothness, formation,formation, andand printabilityprintability z InherentInherent strengthstrength requirementrequirement ofof thethe convertingconverting processprocess dictatesdictates thethe amountamount ofof softwoodsoftwood thatthat isis includedincluded inin thethe furnishfurnish PulpingPulping andand BleachingBleaching z 65%65% ofof thethe pulppulp producedproduced inin thethe worldworld isis mademade byby thethe kraftkraft process.process. z ChemicalChemical pulpingpulping removesremoves mostmost ofof thethe ligninlignin andand hemicelluloseshemicelluloses andand allall ofof thethe extractives.extractives. z However,However, chemicalchemical pulpingpulping resultsresults inin darkdark brownbrown pulppulp thatthat mustmust bebe bleached.bleached. z NearlyNearly allall extrusionextrusion coatedcoated paperpaper andand boardboard isis mademade fromfrom kraftkraft pulp.pulp. PaperPaper StructureStructure z CelluloseCellulose moleculemolecule isis alignedaligned moremore oror lessless parallelparallel toto thethe longlong axisaxis ofof thethe fiber.fiber. z FibersFibers areare hydrophilic.hydrophilic. z FibersFibers expandexpand andand shrinkshrink basedbased onon thethe waterwater contentcontent inin thethe fiberfiber walls.walls. z FibersFibers cancan swellswell upup toto 25%25% inin widthwidth butbut onlyonly slightlyslightly inin length.length. z HydrolysisHydrolysis resultsresults inin fiberfiber swelling,swelling, greatergreater fiberfiber flexibility,flexibility, andand fiberfiber collapse.collapse. PaperPaper StructureStructure Page PaperPaper StructureStructure Side view Top view More fiber collapse Less fiber collapse PaperPaper StructureStructure FiberFiber collapsecollapse dependsdepends on:on: z ThicknessThickness ofof thethe cellcell wallswalls z RatioRatio betweenbetween fiberfiber wallwall thicknessthickness andand fiberfiber widthwidth z AmountAmount ofof ligninlignin leftleft inin thethe fiberfiber wallwall z AmountAmount ofof mechanicalmechanical actionaction z PressurePressure onon thethe paperpaper machinemachine PaperPaper StructureStructure PaperPaper StructureStructure PaperPaper StructureStructure Fiber orientation means that paper is stronger in the machine direction than in the cross machine direction. PaperPaper StructureStructure PaperPaper StructureStructure z MoreMore fiberfiber alignmentalignment inin thethe MDMD isis calledcalled anisotropy.anisotropy. z SonicSonic modulusmodulus relatesrelates toto tensiletensile stiffnessstiffness indexindex (TSI).(TSI). z TSITSI relatesrelates toto fiberfiber orientation.orientation. PaperPaper StructureStructure z TSOTSO isis thethe angleangle ofof maxmax TSO TSI.TSI. z MightMight notnot bebe inin thethe exactexact MD.MD. z VariesVaries acrossacross thethe sheet.sheet. z CalledCalled asymmetricalasymmetrical anisotropy.anisotropy. PaperPaper StructureStructure z FibersFibers swellswell inin width,width, butbut notnot inin length.length. z HumidityHumidity changeschanges affectaffect thethe CDCD moremore thanthan thethe MD.MD. z SameSame problemproblem ifif toptop andand bottombottom ofof thethe sheetsheet isis different.different. z PaperPaper curls.curls. SummarySummary ofof PapermakingPapermaking z PaperPaper isis aa recordrecord ofof allall thethe processesprocesses thatthat havehave occurredoccurred inin itsits production,production, andand thosethose processesprocesses areare inherentlyinherently unstable.unstable. z TheThe physicalphysical propertiesproperties ofof paperpaper areare basedbased onon thethe structurestructure ofof thethe cellulosecellulose molecule,molecule, thethe typetype ofof fiber,fiber, andand howhow thatthat fiberfiber waswas separatedseparated fromfrom thethe otherother componentscomponents ofof thethe wood.wood. z TheThe wayway thethe fibersfibers areare reassembledreassembled stronglystrongly affectsaffects howhow thethe paperpaper reactsreacts toto furtherfurther convertingconverting operationsoperations andand otherother changeschanges inin itsits environment.environment. BaseBase StockStock QuestionsQuestions zzEndEnd useuse requirements?requirements? zzIsIs thethe basebase stockstock mademade toto bebe coated?coated? zzAreAre youyou makingmaking oror buying?buying? zzCanCan youyou specifyspecify oror mustmust youyou adapt?adapt? RollRoll QualityQuality forfor OffOff--MachineMachine CoatingCoating zz CleanClean slitslit edgesedges zz NoNo edgeedge crackscracks zz UniformUniform tensiontension -- nono wrinkleswrinkles zz NoNo holesholes zz SplicesSplices zzMinimalMinimal numbernumber zzProperlyProperly mademade andand markedmarked SpecifyingSpecifying BaseBase StockStock PhysicalPhysical PropertiesProperties z Basis weight z Moisture z Caliper z Strength z Tensile z Tear z Internal bond z Folding endurance z Porosity z Smoothness/roughness z Coefficient of Friction (COF) z Scoring and bending properties SpecifyingSpecifying BaseBase StockStock OpticalOptical PropertiesProperties z BrightnessBrightness z ShadeShade z GlossGloss PaperPaper andand BoardBoard TestingTesting StrengthStrength PropertiesProperties z FoldingFolding EnduranceEndurance z ScottScott BondBond (Internal(Internal Bond)Bond) z StiffnessStiffness z BendingBending ResistanceResistance ofof PaperPaper –– GurleyGurley MethodMethod z StiffnessStiffness ofof PaperboardPaperboard –– TaberTaber MethodMethod z TearingTearing ResistanceResistance z TensileTensile StrengthStrength FoldingFolding EnduranceEndurance z Folding endurance is tested using the MIT tester z A strip of paper is mounted under tension in the tester z The tester rotates back and forth through 270° z The number of double folds is reported – either as raw data or log10 z ISO 5626 and TAPPI T 511 are the folding endurance test methods ScottScott InternalInternal BondBond z MeasuresMeasures thethe internalinternal bondbond strengthstrength z VeryVery criticalcritical forfor offsetoffset printingprinting –– especiallyespecially sheetsheet fedfed offsetoffset withwith highhigh tacktack inksinks z ResistanceResistance toto fiberfiber pickingpicking z TAPPITAPPI TT 569569 GurleyGurley StiffnessStiffness forfor PaperPaper z BendingBending resistanceresistance isis importantimportant forfor sheetsheet fedfed offsetoffset z SampleSample isis clampedclamped andand usedused toto deflectdeflect aa pendulumpendulum withwith weightweight z DataData isis reportedreported inin GurleyGurley stiffnessstiffness unitunit z TAPPITAPPI TT 543543 TaberTaber StiffnessStiffness forfor PaperboardPaperboard z DeterminesDetermines thethe bendingbending