高分子材料與應(yīng)用(英文版)-Chapter-7-Coatings-and-Adhesives課件

高分子材料與應(yīng)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聚氨酯類增稠劑的增稠機(jī)理之一在于其分子可以水合溶脹而使水相增稠，其二是具有表面活性劑分子的性質(zhì)，其分子是線性親水鏈兩端接有親油基的高分子化合物，即在結(jié)構(gòu)中具有親水和疏水基團(tuán)。這樣，在它的水溶液濃度超過一定值時就形成膠束。膠束能夠與乳液的聚合物粒子、已吸附有分散劑的顏料顆粒相互締合形成空間網(wǎng)狀結(jié)構(gòu)，互相連結(jié)纏繞而使體系粘度增加。因而，聚氨酯類增稠劑也稱為締合型增稠劑。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(流掛)controlfactors:viscosity,layerthicknessSurfaceshrinkage(表面起皺)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(乳膠漆)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粘接是用粘合劑將被粘物表面連接在一起的過程。2surfacescanonlybejoinedwiththeestablishmentofbondsbetweenthem.Theexactnatureofthebonddependsontheadhesiveandthesurfacetobebonded.Itisimportantwhenjoiningmaterialswithtrue

adhesivesthatthesurfacestobecompletely

clean.Evenathincoatingofgreaseorsimilarmaterial

mayreduceconsiderablytheeffectivesurface

tensionofthesurface,impairingthebond.INTRODUCTIONTYPESOFADHESIVECanbedividedinto3types:a)Naturaladhesives

-canbemadefromanimal,vegetableormineralsources

b)Syntheticresinbasedadhesives

i)Thermosettingadhesives

ii)Thermoplasticsyntheticadhesivesc)inorganicadhesivesCOMPONENTSOFADHESIVE(1)粘合物質(zhì)(2)溶劑(3)增粘劑(4)消泡劑(5)增塑劑(6)填料(7)防腐劑(8)稀釋劑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(瀝青)ADHESIVES

Formgoo