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）Chapter7CoatingsandAdhesivesIntroductionWhatarecoatings?Anysubstancesusedtocoverasurfaceandformedanlayeronto.Morespecifically,coatingsmeanspolymerbasedmaterialsusedtocoverasurface.Fourbasicingredients:

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

Fordecoration:

Color,Gloss,etc.

Forsomefunctions:

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

Originalequipmentsmanufacture(OEM,usedinfactory);

SpecialCoatings(usedoutoffactory,forship,equipmentrepair,roadsignsetc.)IntroductionClassification

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,andTopcoatsIntroduction

CoatingFormingProcess

1.Surfacecleaningandpretreatment2.Coatingsareapplied

dipping,spraying,electroplating…3.Theyformfilmsandcure

solventevaporation,bakingorairdrying,free-radicalpolymerization2.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,carsCoatingResinsEpoxiesmedium-tohigh-priced,goodadhesion(primersforautomotive),heatresistance(electricalinsulation),excellenterosionandchemicalresistance.poorultraviolet-lightresistance:usedoutdoors,tendtochalkanddiscolor.Acrylicsoutstandingweatherresistance(architecturalcoatings);lacquersandenamels(thetopcoatsfortheautomotive);excellentexteriordurabilityCoatingResinsPolyurethanesprice>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)CoatingResinsChlorinatedrubber

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

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

PigmentsPigmentVolumeConcentration(PVC)CriticalPVC

WithPVC↑(upto>CPVC),thepolymerscannotfillthespacesbetweenpigmentparticles→Holesappears,strength↓,adhesion↓.FactorsthatcontrolCPVCparticlesize↓,CPVC↑;sizedistribution↑,CPVC↑4.AdditivesFunctionaffectvariousareassuchascolor,waterresistance,slipcontrol,foamcontrol,andgloss.Antioxidant

easilycleavage,formfreeradical;e.g.,Phenoliccompounds,naphthol,primaryandsecondaryaminesAdditives

AssociativethickenersFunction:thickenwater-based(mainlylatex)paintsthroughtheirhydrophobicinteractionwithotherpaintcomponentsThreeproducts:hydrophobicallymodifiedethoxylatedurethanes,HEUR,associativeacrylicthickeners,associativecelluloseetherAdditivesThickeningMechanism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。AdditivesOtheradditivesAcceleratorCuringagentsLightstabilizersDefoamerDispersingagent(dispersant)WettingagentsSurfactant5.Film-formingProcessSolventEvaporationwithsolventvolatilization,viscosity↑,Pigmentmovement↓,sotoplayerwithoutpigments→glossycoatingvolatilizetoofast→toplayerformfilmfirst→coatinglayershrinkageLatexcombinationDifficultytoformglossysurfaceFilmformingTtoolow→molecularmovement↓,latexparticlescannotcombine.Tg↑,Minimumfilmformationtemperature↑.CoatingFilmDefectsLeveling(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.6.EnvironmentfriendlycoatingsUV-curablecoatingsLowVOC,minimumthicknesschangeBasiccomponentsofUVcurablecoatings

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

printingsinks;papercoatings;photo-resistsforprintedcircuitsandmicroeletronicsWaterbornecoatingsWater-reduciblecoatingsWater+Solventasfilm-formingvehiclesCanusehighMwResinLownonvolatileweightWater-solublecoatingsWaterassolventLowwaterresistantLatexcoatings(乳胶漆)LowVOC,HighMw.DifficultytoformhighglossycoatingAdditivecomplication:dispersants,thickeners,etc.Usedinarchitecture.ElectrocoatingOrganiccoatingsaredepositedonproductsfromanelectrolyticbathResinsmustcontainingchargesAdvantagesanddisadvantagesUniformfilmthicknesses,lowVOC,lesslabor-intensive;highcapitalequipmentcosts,highermaterialcosts,andmorethoroughpretreatment.Application:BottomcoatingforCars;metalproducts.PowderCoatingsResintypeThermoplastic&ThermosettingFilmformationonpreheatedproductsCoatingMethodsFluidized-bedpowdercoating.Electrostaticfluidized-bedpowdercoatingElectrostatic-spraypowdercoatingAdvantages&disadvantagesLowVOC;thicknessupto500μm;lowenergycost.ExplosionRisk;cannotbeusedinthermosensitiveproducts.SummaryTraditionalcoatingshavefourbasicingredients.Environment-friendlycoatingshavebrightfuture.Coatingindustriesarereallytechnology-intensive.ADHESIVES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.INTRODUCTIONTYPESOFADHESIVECanbedividedinto3types:a)Naturaladhesives

-canbemadefromanimal,vegetableormineralsources

b)Syntheticresinbasedadhesives

i)Thermosettingadhesives

ii)Thermoplasticsyntheticadhesivesc)inorganicadhesivesCOMPONENTSOFADHESIVE(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NaturalAdhesivesANIMALGLUEShavebeenusedforcenturiesincarpentryandjoineryObtainedfromtheskin/bonesofcattleandsheepAnimalgluesusuallysoldinpowderandmeltedin

warmwatertogiveasolutionofsuitableviscosity.Coolingoftheliquidafterapplicationresultsinrapidgelling,producingsomestrengthanddryingfinallyproducesatoughandrigidproduct.Removalofthewaterfromglueduringcuringis

essential;thewoodassistinthisprocess,dueto

absorption.

Gluedjointsinwoodshouldbeasstrongas

thewood.Dampconditionwillreducestrengthofglue.Animalglueisnotsuitableforexternaluse

unlessadequatelyprotectedfrommoisture.Thegluewillhardengraduallyinthepotbut

canbesoftenedbyreheatingwithwater.Ifafailureoccursinsuchitemsitiseasyto

carryoutrepairsbysofteningthegluewith

water.AnimalGluesCASEINGLUESItisderivedasaprecipitatefromskimmed

milkbytheactionofacids.Gluesareobtainedinpowderformthatalso

containalkalinesolvent,necessarytodissolve

theglueonadditionofwater.Mixingiscarriedoutincoldandsettingis

partlybyevaporationorabsorptionofwater

andpartlybyanaturalgelationprocess.ItsadhesiontoporousmaterialisgoodItsmoistureresistanceissuperiorthananimal

glueCaseinGlue–ADryGlueDerivedFromMilkVEGETABLEGLUEMadefromstarches(淀粉)ordextrin(糊精)lowcostlimitedstrengthandlimitedmoisture

resistanceGumArabicisawatersolublevegetable

adhesiveoftenusedonstampsandgummed

paperenvelopes.CellulosePowderATypeofVegetableAdhesiveWheatPasteATypeofVegetableAdhesiveTHERMOSETTINGADHESIVESUREAFORMALDEHYDEOneofthecommonestadhesivesinjoineryforgeneralpurposes,producingastrongrigidjointiftheglue-lineisthin.Itprovidesastrongadhesioninapermanentlydryenvironment,curesfast,andisrelativelycheap.Tomaketheadhesive,formaldehydeandurea

inaqueoussolutionareallowedtoreacttogethertoacertainstageandthereactionisthenstoppedwhiletheresinisstillliquid.Theyarebestsuitedforjoiningporousmaterialsuchaswood.Itisusedforfabricationofflushcolours,laminatedtimberanddecorativelaminates.Ithasagoodwaterresistancebutifveryhot

waterorprolongedwettingitcouldbreaksthe

resindown.MELAMINEFORMALDEHYDERESINADHESIVES

Suppliedinpowderform&mixedwithwater

togiveacolourlessresin.Setonheatingto100°CGivegoodweatherresistance&expensive

thanureaformaldehydeadhesivePHENOLFORMALDEHYDEavailableasliquidsthatpolymeriseonheating

totemperatureover100°C.UsedforassemblyofplywoodsheetsTheresinisapplied,thesheetsformedandthe

laminatesisthensubjectedtoahotpressthat

causeshardeninginaperiodofabout5min.Cold-curingphenolicadhesivesarealso

available.CanbeappliedforPlywood,blockboards,

flushdoorsEPOXYRESINSItformagoodbondwithalmostanymaterial.Itiswidelyusedforstructuraljointsbetween

manytypesofmaterialincludingglass,metal,

thermosettingplasticsandconcrete.HaveexcellentmechanicalstrengthHaveexcellentcreepresistanceResistanttoweather,acids,alkalisandmost

hydrocarbon.EpoxyResinEpoxyResinAlkylCyanoacrylateAdhesivesHaveadvantageofpolymerisingveryrapidly

whenspreadinthinfilms.Thereactionbeingcatalysedbywaterintheverysmallquantitiesrequiredwhichispresent

onmostsurfaces.Expensivesousesareconfinedtobondingof

smallobjectshavingsurfacesthatclosely

conformtooneanother.TheyformthebasisofSuperglues.Mustbehandledwithcaretoavoidbondingof

skintissues.THERMOPLASTICADHESIVES

Settingactionofthesemayduetocooling,

solventevaporationoremulsioncoalescence.Thisadhesiveismoreflexiblebutweakerand

morepronetocreepthanthermosetting

adhesives.So,theyarenormallynotusedforstructural

purposes.POLYVINYLACETATEMostimportantthermoplasticadhesivein

building.Chiefapplicationbeingasawoodadhesivefor

internaluseandasabondingagentforconcrete.MostcommonlyusedinemulsionformThispolymerisobtainedfromacetylene&aceticacid.Theadhesivesetswhenthesolidparticles,on

evaporationorabsorptionofthemoisture,

coheretoformatough,clearfilmwhichisno

longerwatersoluble.PolyvinylAcetateUsedForBookBindingBITUMINOUS(沥青)ADHESIVES

Formgoo