高分子材料与应用(英文版)-Chapter-7-Coatings-and-Adhesives课件

高分子材料与应用（英文版）Chapter7CoatingsandAdhesives高分子材料与应用（英文版）Chapter7Coatin1IntroductionWhatarecoatings?Anysubstancesusedtocoverasurfaceandformedanlayeronto.Morespecifically,coatingsmeanspolymerbasedmaterialsusedtocoverasurface.Fourbasicingredients:

film-formingvehicles,pigments,solvents,andadditives.IntroductionWhatarecoatings?2IntroductionWhyCoatings?

Fordecoration:

Color,Gloss,etc.

Forsomefunctions:

erosionresistance,abrasionresistance,slipcontrol,fungalresistance,etc.ApplicationfieldArchitectureandfurniture(paint,漆);

Originalequipmentsmanufacture(OEM,usedinfactory);

SpecialCoatings(usedoutoffactory,forship,equipmentrepair,roadsignsetc.)IntroductionWhyCoatings?3IntroductionClassification

Basedonresintype:

alkyd,polyurethane,polyester,epoxy,…..Basedonenvironmentimpact:

Traditionalsolventcoatings:VOC→pollution

Environment-friendly:Waterborne,HighSolid,Powder,UV-curing…Basedonfinish(漆；末道漆)system:One-coat,Multicoatprimers,Intermediatecoats,andTopcoatsIntroductionClassification4Introduction

CoatingFormingProcess

1.Surfacecleaningandpretreatment2.Coatingsareapplied

dipping,spraying,electroplating…3.Theyformfilmsandcure

solventevaporation,bakingorairdrying,free-radicalpolymerizationIntroductionCoatin52.CoatingResins

AlkydsSynthesis:

fattyAcid+Polyacid+PolyolAdvantages:

lowcost;interiorexposuresgenerallygood.Disadvantages:

exteriordurabilityonlyfairApplication

finishingmetalandwoodproducts.PolyesterSynthesis:

Polyacid+Polyol+(Styrene)Advantages:

goodinterior&exteriordurabilityDisadvantages:

costishigherApplication:

furniture,appliances,automobiles,magnetwire2components:glass-reinforcedplasticbathtubs,lavatories,boats,cars2.CoatingResinsAlkydsPo6CoatingResinsEpoxiesmedium-tohigh-priced,goodadhesion(primersforautomotive),heatresistance(electricalinsulation),excellenterosionandchemicalresistance.poorultraviolet-lightresistance:usedoutdoors,tendtochalkanddiscolor.Acrylicsoutstandingweatherresistance(architecturalcoatings);lacquersandenamels(thetopcoatsfortheautomotive);excellentexteriordurabilityCoatingResinsEpoxies7CoatingResinsPolyurethanesprice>alkydsbut<epoxies.availableasoil-modified,moisturecuring,blocked,two-component,andlacquers.

abrasion-resistant,flexible,resilient,tough,chemical-resistant,andweather-resistant.

veryimportantfinishesinthetransportationindustry,includesaircraft,automobiles,railroads,trucks,andships;militarylandvehicles,ships,andaircraft(chemical&radiologicalresistance)CoatingResinsPolyurethanes8CoatingResinsChlorinatedrubber

usedasswimmingpoolpaintsandtrafficpaints.Fluorocarbonsnonstickproperties(forcookware).Polyamidestough,wear-resistant,arelativelylowcoefficientoffriction(forofficefurniture)Polyolefinsmoistureproof(forchemical-processingandfood-handlingequipment)CoatingResinsChlorinatedrubb93.PigmentsDefinitioninsolubleparticlesdispersedintheliquidportionofthepaint.Functiongivedesiredcolorandgloss,plusprovide"hidingability"(proportionedtorefractiveIndex)andprotection.ClassificationOrganic,inorganic,metallic;White&Color.3.PigmentsDefinition10

PigmentsPigmentDispersionThreeStepsWetting;separatinglargemass;StabilizingthesmallparticlesStabilizingMechanismsForsolventcoating:Polymeradsorption(entropyexclusion):layer>4.5nmForwater-borncoating:needdispersants;ionicinteraction,hydrophobicandhydrophilicbalance.PigmentsPigmentDispersion11

PigmentsPigmentVolumeConcentration(PVC)CriticalPVC

WithPVC↑(upto>CPVC),thepolymerscannotfillthespacesbetweenpigmentparticles→Holesappears,strength↓,adhesion↓.FactorsthatcontrolCPVCparticlesize↓,CPVC↑;sizedistribution↑,CPVC↑PigmentsPigmentVolumeConcen124.AdditivesFunctionaffectvariousareassuchascolor,waterresistance,slipcontrol,foamcontrol,andgloss.Antioxidant

easilycleavage,formfreeradical;e.g.,Phenoliccompounds,naphthol,primaryandsecondaryamines4.AdditivesFunction13Additives

AssociativethickenersFunction:thickenwater-based(mainlylatex)paintsthroughtheirhydrophobicinteractionwithotherpaintcomponentsThreeproducts:hydrophobicallymodifiedethoxylatedurethanes,HEUR,associativeacrylicthickeners,associativecelluloseetherAdditivesAssociati14AdditivesThickeningMechanism聚氨酯类增稠剂的增稠机理之一在于其分子可以水合溶胀而使水相增稠，其二是具有表面活性剂分子的性质，其分子是线性亲水链两端接有亲油基的高分子化合物，即在结构中具有亲水和疏水基团。这样，在它的水溶液浓度超过一定值时就形成胶束。胶束能够与乳液的聚合物粒子、已吸附有分散剂的颜料颗粒相互缔合形成空间网状结构，互相连结缠绕而使体系粘度增加。因而，聚氨酯类增稠剂也称为缔合型增稠剂。AdditivesThickeningMechanism聚15AdditivesOtheradditivesAcceleratorCuringagentsLightstabilizersDefoamerDispersingagent(dispersant)WettingagentsSurfactantAdditivesOtheradditives165.Film-formingProcessSolventEvaporationwithsolventvolatilization,viscosity↑,Pigmentmovement↓,sotoplayerwithoutpigments→glossycoatingvolatilizetoofast→toplayerformfilmfirst→coatinglayershrinkageLatexcombinationDifficultytoformglossysurfaceFilmformingTtoolow→molecularmovement↓,latexparticlescannotcombine.Tg↑,Minimumfilmformationtemperature↑.5.Film-formingProcessSolvent17CoatingFilmDefectsLeveling(流平)drivenforce:surfacetension(σ).peakarea:coatinglayer↑→solventvolatilization↓→σ>valleyarea→flowfrompeaktovalley.controlfactors:viscosity,layerthickness.Sagging(流挂)controlfactors:viscosity,layerthicknessSurfaceshrinkage(表面起皱)Surfacevolatilization(cure)>bulk→surfaceformfilmfirst→Surfaceshrinkage

Controlfactors:layerthickness,

volatilization(cure)speed.CoatingFilmDefectsLeveling(186.EnvironmentfriendlycoatingsUV-curablecoatingsLowVOC,minimumthicknesschange6.Environmentfriendlycoatin19BasiccomponentsofUVcurablecoatings

BasiccomponentsofUVcurable20UV-curableCoatingsAdvantagesLowVOC,lowenergycost,lowequipmentinvestment.DisadvantagesThicknesslimit:pigment;polymerizationshrinkagePhotoinitiatorleftover:poorexteriordurability.Applications

printingsinks;papercoatings;photo-resistsforprintedcircuitsandmicroeletronicsUV-curableCoatingsAdvantages21WaterbornecoatingsWater-reduciblecoatingsWater+Solventasfilm-formingvehiclesCanusehighMwResinLownonvolatileweightWater-solublecoatingsWaterassolventLowwaterresistantLatexcoatings(乳胶漆)LowVOC,HighMw.DifficultytoformhighglossycoatingAdditivecomplication:dispersants,thickeners,etc.Usedinarchitecture.WaterbornecoatingsWater-reduc22ElectrocoatingOrganiccoatingsaredepositedonproductsfromanelectrolyticbathResinsmustcontainingchargesAdvantagesanddisadvantagesUniformfilmthicknesses,lowVOC,lesslabor-intensive;highcapitalequipmentcosts,highermaterialcosts,andmorethoroughpretreatment.Application:BottomcoatingforCars;metalproducts.ElectrocoatingOrganiccoatings23PowderCoatingsResintypeThermoplastic&ThermosettingFilmformationonpreheatedproductsCoatingMethodsFluidized-bedpowdercoating.Electrostaticfluidized-bedpowdercoatingElectrostatic-spraypowdercoatingAdvantages&disadvantagesLowVOC;thicknessupto500μm;lowenergycost.ExplosionRisk;cannotbeusedinthermosensitiveproducts.PowderCoatingsResintype24SummaryTraditionalcoatingshavefourbasicingredients.Environment-friendlycoatingshavebrightfuture.Coatingindustriesarereallytechnology-intensive.SummaryTraditionalcoatingsha25ADHESIVESADHESIVES26粘接是用粘合剂将被粘物表面连接在一起的过程。2surfacescanonlybejoinedwiththeestablishmentofbondsbetweenthem.Theexactnatureofthebonddependsontheadhesiveandthesurfacetobebonded.Itisimportantwhenjoiningmaterialswithtrue

adhesivesthatthesurfacestobecompletely

clean.Evenathincoatingofgreaseorsimilarmaterial

mayreduceconsiderablytheeffectivesurface

tensionofthesurface,impairingthebond.INTRODUCTION粘接是用粘合剂将被粘物表面连接在一起的过程。2surfa27TYPESOFADHESIVECanbedividedinto3types:a)Naturaladhesives

-canbemadefromanimal,vegetableormineralsources

b)Syntheticresinbasedadhesives

i)Thermosettingadhesives

ii)Thermoplasticsyntheticadhesivesc)inorganicadhesivesTYPESOFADHESIVECanbedivide28COMPONENTSOFADHESIVE(1)粘合物质(2)溶剂(3)增粘剂(4)消泡剂(5)增塑剂(6)填料(7)防腐剂(8)稀释剂COMPONENTSOFADHESIVE(1)粘合物质29NaturalAdhesivesANIMALGLUEShavebeenusedforcenturiesincarpentryandjoineryObtainedfromtheskin/bonesofcattleandsheepAnimalgluesusuallysoldinpowderandmeltedin

warmwatertogiveasolutionofsuitableviscosity.Coolingoftheliquidafterapplicationresultsinrapidgelling,producingsomestrengthanddryingfinallyproducesatoughandrigidproduct.Removalofthewaterfromglueduringcuringis

essential;thewoodassistinthisprocess,dueto

absorption.NaturalAdhesivesANIMALGLUES30

Gluedjointsinwoodshouldbeasstrongas

thewood.Dampconditionwillreducestrengthofglue.Animalglueisnotsuitableforexternaluse

unlessadequatelyprotectedfrommoisture.Thegluewillhardengraduallyinthepotbut

canbesoftenedbyreheatingwithwater.Ifafailureoccursinsuchitemsitiseasyto

carryoutrepairsbysofteningthegluewith

water.Gluedjointsinwoodshouldb31AnimalGluesAnimalGlues32CASEINGLUESItisderivedasaprecipitatefromskimmed

milkbytheactionofacids.Gluesareobtainedinpowderformthatalso

containalkalinesolvent,necessarytodissolve

theglueonadditionofwater.Mixingiscarriedoutincoldandsettingis

partlybyevaporationorabsorptionofwater

andpartlybyanaturalgelationprocess.ItsadhesiontoporousmaterialisgoodItsmoistureresistanceissuperiorthananimal

glueCASEINGLUES33CaseinGlue–ADryGlueDerivedFromMilkCaseinGlue–ADryGlueDeriv34VEGETABLEGLUEMadefromstarches(淀粉)ordextrin(糊精)lowcostlimitedstrengthandlimitedmoisture

resistanceGumArabicisawatersolublevegetable

adhesiveoftenusedonstampsandgummed

paperenvelopes.VEGETABLEGLUE35CellulosePowderATypeofVegetableAdhesiveCellulosePowderATypeofVeg36WheatPasteATypeofVegetableAdhesiveWheatPasteATypeofVegetabl37THERMOSETTINGADHESIVESUREAFORMALDEHYDEOneofthecommonestadhesivesinjoineryforgeneralpurposes,producingastrongrigidjointiftheglue-lineisthin.Itprovidesastrongadhesioninapermanentlydryenvironment,curesfast,andisrelativelycheap.THERMOSETTINGADHESIVESUREAFO38Tomaketheadhesive,formaldehydeandurea

inaqueoussolutionareallowedtoreacttogethertoacertainstageandthereactionisthenstoppedwhiletheresinisstillliquid.Theyarebestsuitedforjoiningporousmaterialsuchaswood.Itisusedforfabricationofflushcolours,laminatedtimberanddecorativelaminates.Ithasagoodwaterresistancebutifveryhot

waterorprolongedwettingitcouldbreaksthe

resindown.Tomaketheadhesive,formalde39MELAMINEFORMALDEHYDERESINADHESIVES

Suppliedinpowderform&mixedwithwater

togiveacolourlessresin.Setonheatingto100°CGivegoodweatherresistance&expensive

thanureaformaldehydeadhesiveMELAMINEFORMALDEHYDERESIN40PHENOLFORMALDEHYDEavailableasliquidsthatpolymeriseonheating

totemperatureover100°C.UsedforassemblyofplywoodsheetsTheresinisapplied,thesheetsformedandthe

laminatesisthensubjectedtoahotpressthat

causeshardeninginaperiodofabout5min.Cold-curingphenolicadhesivesarealso

available.CanbeappliedforPlywood,blockboards,

flushdoorsPHENOLFORMALDEHYDE41EPOXYRESINSItformagoodbondwithalmostanymaterial.Itiswidelyusedforstructuraljointsbetween

manytypesofmaterialincludingglass,metal,

thermosettingplasticsandconcrete.HaveexcellentmechanicalstrengthHaveexcellentcreepresistanceResistanttoweather,acids,alkalisandmost

hydrocarbon.EPOXYRESINS42EpoxyResinEpoxyResin43EpoxyResinEpoxyResin44AlkylCyanoacrylateAdhesivesHaveadvantageofpolymerisingveryrapidly

whenspreadinthinfilms.Thereactionbeingcatalysedbywaterintheverysmallquantitiesrequiredwhichispresent

onmostsurfaces.Expensivesousesareconfinedtobondingof

smallobjectshavingsurfacesthatclosely

conformtooneanother.TheyformthebasisofSuperglues.Mustbehandledwithcaretoavoidbondingof

skintissues.AlkylCyanoacrylateAdhesives45THERMOPLASTICADHESIVES

Settingactionofthesemayduetocooling,

solventevaporationoremulsioncoalescence.Thisadhesiveismoreflexiblebutweakerand

morepronetocreepthanthermosetting

adhesives.So,theyarenormallynotusedforstructural

purposes.THERMOPLASTICADHESIVESSettin46POLYVINYLACETATEMostimportantthermoplasticadhesivein

building.Chiefapplicationbeingasawoodadhesivefor

internaluseandasabondingagentforconcrete.MostcommonlyusedinemulsionformThispolymerisobtainedfromacetylene&aceticacid.Theadhesivesetswhenthesolidparticles,on

evaporationorabsorptionofthemoisture,

coheretoformatough,clearfilmwhichisno

longerwatersoluble.POLYVINYLACETATE47PolyvinylAcetateUsedForBookBindingPolyvinylAcetateUsedForBoo48BITUMINOUS(沥青)ADHESIVES

FormgoodbondswithanumberofmaterialsMoistureresistantFlexibleNaturalorSyntheticrubber&solventsmaybe

includedtogivethedesiredcombinationof

elasticityandstrength.Canbeobtainedin3formthatis

a)WaterBasedEmulsion

b)SolventTypesc)Hot-AppliedVarietiesBITUMINOUS(沥青)ADHESIVES49WaterBasedEmulsions

-Formaneffectivebondbetweenporous

materialsinsituationswherelongtermtensile

stressesarenotpresent.

-Alsousedforlayingwood-blockflooringand

PVCorthermoplastictilesHot-AppliedVarieties

-Usedforwood-blockflooringandin

built-upfeltroofing.

-Applicationtemperatureintheregionof

150°C–200°CWaterBasedEmulsions

-Form50SolventTypes

-UsedinlayinglinoleumandforPVCandthermoplastictilesthoughtestshouldbecarriedouttoensurethatstainingdoesn’toccur. -Bothsolventandemulsiontypesrelyonsomedegreeofabsorbencyinthesubstratetoallowabsorption/evaporationofthewaterorsolvent.SolventTypes

-Usedinlayin51RUBBERBASEDADHESIVESThemostimportantrubberbasedadhesivesintheconstructionindustryarecontactadhesivesTheadhesiveisappliedtobothsurfacesandaftersolventevaporation,thesurfacesarecarefullybroughttogether,givingimmediateauto-adhesion.Latexessuchasstyrenebutadienerubber(SBR)arewidelyusedforfloorcoverings.Latex-modifiedcementsareusedforbondingceramictilestoavarietyofbackgrounds,includingmetal.RUBBERBASEDADHESIVES52ThankYouThankYou53高分子材料与应用（英文版）Chapter7CoatingsandAdhesives高分子材料与应用（英文版）Chapter7Coatin54IntroductionWhatarecoatings?Anysubstancesusedtocoverasurfaceandformedanlayeronto.Morespecifically,coatingsmeanspolymerbasedmaterialsusedtocoverasurface.Fourbasicingredients:

film-formingvehicles,pigments,solvents,andadditives.IntroductionWhatarecoatings?55IntroductionWhyCoatings?

Fordecoration:

Color,Gloss,etc.

Forsomefunctions:

erosionresistance,abrasionresistance,slipcontrol,fungalresistance,etc.ApplicationfieldArchitectureandfurniture(paint,漆);

Originalequipmentsmanufacture(OEM,usedinfactory);

SpecialCoatings(usedoutoffactory,forship,equipmentrepair,roadsignsetc.)IntroductionWhyCoatings?56IntroductionClassification

Basedonresintype:

alkyd,polyurethane,polyester,epoxy,…..Basedonenvironmentimpact:

Traditionalsolventcoatings:VOC→pollution

Environment-friendly:Waterborne,HighSolid,Powder,UV-curing…Basedonfinish(漆；末道漆)system:One-coat,Multicoatprimers,Intermediatecoats,andTopcoatsIntroductionClassification57Introduction

CoatingFormingProcess

1.Surfacecleaningandpretreatment2.Coatingsareapplied

dipping,spraying,electroplating…3.Theyformfilmsandcure

solventevaporation,bakingorairdrying,free-radicalpolymerizationIntroductionCoatin582.CoatingResins

AlkydsSynthesis:

fattyAcid+Polyacid+PolyolAdvantages:

lowcost;interiorexposuresgenerallygood.Disadvantages:

exteriordurabilityonlyfairApplication

finishingmetalandwoodproducts.PolyesterSynthesis:

Polyacid+Polyol+(Styrene)Advantages:

goodinterior&exteriordurabilityDisadvantages:

costishigherApplication:

furniture,appliances,automobiles,magnetwire2components:glass-reinforcedplasticbathtubs,lavatories,boats,cars2.CoatingResinsAlkydsPo59CoatingResinsEpoxiesmedium-tohigh-priced,goodadhesion(primersforautomotive),heatresistance(electricalinsulation),excellenterosionandchemicalresistance.poorultraviolet-lightresistance:usedoutdoors,tendtochalkanddiscolor.Acrylicsoutstandingweatherresistance(architecturalcoatings);lacquersandenamels(thetopcoatsfortheautomotive);excellentexteriordurabilityCoatingResinsEpoxies60CoatingResinsPolyurethanesprice>alkydsbut<epoxies.availableasoil-modified,moisturecuring,blocked,two-component,andlacquers.

abrasion-resistant,flexible,resilient,tough,chemical-resistant,andweather-resistant.

veryimportantfinishesinthetransportationindustry,includesaircraft,automobiles,railroads,trucks,andships;militarylandvehicles,ships,andaircraft(chemical&radiologicalresistance)CoatingResinsPolyurethanes61CoatingResinsChlorinatedrubber

usedasswimmingpoolpaintsandtrafficpaints.Fluorocarbonsnonstickproperties(forcookware).Polyamidestough,wear-resistant,arelativelylowcoefficientoffriction(forofficefurniture)Polyolefinsmoistureproof(forchemical-processingandfood-handlingequipment)CoatingResinsChlorinatedrubb623.PigmentsDefinitioninsolubleparticlesdispersedintheliquidportionofthepaint.Functiongivedesiredcolorandgloss,plusprovide"hidingability"(proportionedtorefractiveIndex)andprotection.ClassificationOrganic,inorganic,metallic;White&Color.3.PigmentsDefinition63

PigmentsPigmentDispersionThreeStepsWetting;separatinglargemass;StabilizingthesmallparticlesStabilizingMechanismsForsolventcoating:Polymeradsorption(entropyexclusion):layer>4.5nmForwater-borncoating:needdispersants;ionicinteraction,hydrophobicandhydrophilicbalance.PigmentsPigmentDispersion64

PigmentsPigmentVolumeConcentration(PVC)CriticalPVC

WithPVC↑(upto>CPVC),thepolymerscannotfillthespacesbetweenpigmentparticles→Holesappears,strength↓,adhesion↓.FactorsthatcontrolCPVCparticlesize↓,CPVC↑;sizedistribution↑,CPVC↑PigmentsPigmentVolumeConcen654.AdditivesFunctionaffectvariousareassuchascolor,waterresistance,slipcontrol,foamcontrol,andgloss.Antioxidant

easilycleavage,formfreeradical;e.g.,Phenoliccompounds,naphthol,primaryandsecondaryamines4.AdditivesFunction66Additives

AssociativethickenersFunction:thickenwater-based(mainlylatex)paintsthroughtheirhydrophobicinteractionwithotherpaintcomponentsThreeproducts:hydrophobicallymodifiedethoxylatedurethanes,HEUR,associativeacrylicthickeners,associativecelluloseetherAdditivesAssociati67AdditivesThickeningMechanism聚氨酯类增稠剂的增稠机理之一在于其分子可以水合溶胀而使水相增稠，其二是具有表面活性剂分子的性质，其分子是线性亲水链两端接有亲油基的高分子化合物，即在结构中具有亲水和疏水基团。这样，在它的水溶液浓度超过一定值时就形成胶束。胶束能够与乳液的聚合物粒子、已吸附有分散剂的颜料颗粒相互缔合形成空间网状结构，互相连结缠绕而使体系粘度增加。因而，聚氨酯类增稠剂也称为缔合型增稠剂。AdditivesThickeningMechanism聚68AdditivesOtheradditivesAcceleratorCuringagentsLightstabilizersDefoamerDispersingagent(dispersant)WettingagentsSurfactantAdditivesOtheradditives695.Film-formingProcessSolventEvaporationwithsolventvolatilization,viscosity↑,Pigmentmovement↓,sotoplayerwithoutpigments→glossycoatingvolatilizetoofast→toplayerformfilmfirst→coatinglayershrinkageLatexcombinationDifficultytoformglossysurfaceFilmformingTtoolow→molecularmovement↓,latexparticlescannotcombine.Tg↑,Minimumfilmformationtemperature↑.5.Film-formingProcessSolvent70CoatingFilmDefectsLeveling(流平)drivenforce:surfacetension(σ).peakarea:coatinglayer↑→solventvolatilization↓→σ>valleyarea→flowfrompeaktovalley.controlfactors:viscosity,layerthickness.Sagging(流挂)controlfactors:viscosity,layerthicknessSurfaceshrinkage(表面起皱)Surfacevolatilization(cure)>bulk→surfaceformfilmfirst→Surfaceshrinkage

Controlfactors:layerthickness,

volatilization(cure)speed.CoatingFilmDefectsLeveling(716.EnvironmentfriendlycoatingsUV-curablecoatingsLowVOC,minimumthicknesschange6.Environmentfriendlycoatin72BasiccomponentsofUVcurablecoatings

BasiccomponentsofUVcurable73UV-curableCoatingsAdvantagesLowVOC,lowenergycost,lowequipmentinvestment.DisadvantagesThicknesslimit:pigment;polymerizationshrinkagePhotoinitiatorleftover:poorexteriordurability.Applications

printingsinks;papercoatings;photo-resistsforprintedcircuitsandmicroeletronicsUV-curableCoatingsAdvantages74WaterbornecoatingsWater-reduciblecoatingsWater+Solventasfilm-formingvehiclesCanusehighMwResinLownonvolatileweightWater-solublecoatingsWaterassolventLowwaterresistantLatexcoatings(乳胶漆)LowVOC,HighMw.DifficultytoformhighglossycoatingAdditivecomplication:dispersants,thickeners,etc.Usedinarchitecture.WaterbornecoatingsWater-reduc75ElectrocoatingOrganiccoatingsaredepositedonproductsfromanelectrolyticbathResinsmustcontainingchargesAdvantagesanddisadvantagesUniformfilmthicknesses,lowVOC,lesslabor-intensive;highcapitalequipmentcosts,highermaterialcosts,andmorethoroughpretreatment.Application:BottomcoatingforCars;metalproducts.ElectrocoatingOrganiccoatings76PowderCoatingsResintypeThermoplastic&ThermosettingFilmformationonpreheatedproductsCoatingMethodsFluidized-bedpowdercoating.Electrostaticfluidized-bedpowdercoatingElectrostatic-spraypowdercoatingAdvantages&disadvantagesLowVOC;thicknessupto500μm;lowenergycost.ExplosionRisk;cannotbeusedinthermosensitiveproducts.PowderCoatingsResintype77SummaryTraditionalcoatingshavefourbasicingredients.Environment-friendlycoatingshavebrightfuture.Coatingindustriesarereallytechnology-intensive.SummaryTraditionalcoatingsha78ADHESIVESADHESIVES79粘接是用粘合剂将被粘物表面连接在一起的过程。2surfacescanonlybejoinedwiththeestablishmentofbondsbetweenthem.Theexactnatureofthebonddependsontheadhesiveandthesurfacetobebonded.Itisimportantwhenjoiningmaterialswithtrue

adhesivesthatthesurfacestobecompletely

clean.Evenathincoatingofgreaseorsimilarmaterial

mayreduceconsiderablytheeffectivesurface

tensionofthesurface,impairingthebond.INTRODUCTION粘接是用粘合剂将被粘物表面连接在一起的过程。2surfa80TYPESOFADHESIVECanbedividedinto3types:a)Naturaladhesives

-canbemadefromanimal,vegetableormineralsources

b)Syntheticresinbasedadhesives

i)Thermosettingadhesives

ii)Thermoplasticsyntheticadhesivesc)inorganicadhesivesTYPESOFADHESIVECanbedivide81COMPONENTSOFADHESIVE(1)粘合物质(2)溶剂(3)增粘剂(4)消泡剂(5)增塑剂(6)填料(7)防腐剂(8)稀释剂COMPONENTSOFADHESIVE(1)粘合物质82NaturalAdhesivesANIMALGLUEShavebeenusedforcenturiesincarpentryandjoineryObtainedfromtheskin/bonesofcattleandsheepAnimalgluesusuallysoldinpowderandmeltedin

warmwatertogiveasolutionofsuitableviscosity.Coolingoftheliquidafterapplicationresultsinrapidgelling,producingsomestrengthanddryingfinallyproducesatoughandrigidproduct.Removalofthewaterfromglueduringcuringis

essential;thewoodassistinthisprocess,dueto

absorption.NaturalAdhesivesANIMALGLUES83

Gluedjointsinwoodshouldbeasstrongas

thewood.Dampconditionwillreducestrengthofglue.Animalglueisnotsuitableforexternaluse

unlessadequatelyprotectedfrommoisture.Thegluewillhardengraduallyinthepotbut

canbesoftenedbyreheatingwithwater.Ifafailureoccursinsuchitemsitiseasyto

carryoutrepairsbysofteningthegluewith

water.Gluedjointsinwoodshouldb84AnimalGluesAnimalGlues85CASEINGLUESItisderivedasaprecipitatefromskimmed

milkbytheactionofacids.Gluesareobtainedinpowderformthatalso

containalkalinesolvent,necessarytodissolve

theglueonadditionofwater.Mixingiscarriedoutincoldandsettingis

partlybyevaporationorabsorptionofwater

andpartlybyanaturalgelationprocess.ItsadhesiontoporousmaterialisgoodItsmoistureresistanceissuperiorthananimal

glueCASEINGLUES86CaseinGlue–ADryGlueDerivedFromMilkCaseinGlue–ADryGlueDeriv87VEGETABLEGLUEMadefromstarches(淀粉)ordextrin(糊精)lowcostlimitedstrengthandlimitedmoisture

resistanceGumArabicisawatersolublevegetable

adhesiveoftenusedonstampsandgummed

paperenvelopes.VEGETABLEGLUE88CellulosePowderATypeofVegetableAdhesiveCellulosePowderATypeofVeg89WheatPasteATypeofVegetableAdhesiveWheatPasteATypeofVegetabl90THERMOSETTINGADHESIVESUREAFORMALDEHYDEOneofthecommonestadhesivesinjoineryforgeneralpurpos