2.2.1IsocyanatesAsarule,isocyanatesareobtainedbythephosgenationofthecorrespondingprimaryamines(Fig.2-1).Fig.2-1ManufactureofisocyanatesbyphosgenationofprimaryaminesAlternatively,phosgene-freemanufacturingprocesseshavebeendeveloped.Onesuchprocessinvolvesre......
6.1.1Thepurpose,principleandvarietiesofembossing6.1.1.1ThepurposeofembossingEmbossingisanimportantpost-processingtoolforsyntheticleatheranditismainlyusedinthemodificationofthesurfacetextureofsyntheticleatherwithcoatingobtainedbywetprocess.Bymechanicalembo......
3.3.1Preparationforwebforming3.3.1.1ProceduresbeforewebformingThefiberswithcertainlengthandlineardensitycanbeformedwebbycarding.Butinordertoachievefavorablecardingeffect,therawmaterialsmustbetreatedbyaseriesofprocessingbeforecarding.Theprocessbeforewebfor......
Therearemanydyeingmethodstomicrofiber.Itcanbedividedintojigdyeing,overflowdyeingandairflowdyeingaccordingtotheequipments.Basingontheprocessitisdividedintohigh-temperatureandhigh-pressuremethod,andlow-temperatureandnormal-pressuremethod.Everymethodhasitsow......
Theterm“finishing”referstothefurtherprocessingoftheleatherafterdrying.Theaimistoadapttheleathertothefashiondemandsoftheconsumerwithregardtocolor,surfaceeffect,etc.bycoatingitwithmixtureofpigment,filmformingmaterial,etc.Itisusuallycarriedoutonfinishingmach......
Afterretanning,dyeingandfatliquoring,theleathersarehorsedupovernighttoallowexcessliquortodrainoff.Thentheleathersaresammedandsetouttoreducethewatercontentfurther.Atthisstage,theleatherstillcontainsabout50%-60%water.Thisremainingwaterwillhavetobereducedtoa......
Chromeleathersaredyedeitherdiscontinuouslyindrumsorcontinuouslyonthemachines(through-feeddyeing,spraydyeingordyeingbyrollercoating).Whentheyaredyedindrums,itisusuallycarriedoutduringtheprocessesofretanningandfatliquroingafterneutralizing.However,whentheya......
Afterchrometanningitiscommontoallowexcesschromeliquortodrainoffthewet-blue,andtostandtheminadampconditionforadayormore.Furtherfixationofchromeandsettingofthewet-bluefibersoccur.Whereaflatleatherisrequired,thewet-bluesaredrainedflattoavoidanytendencyforthe......
Practicalunhairingsystemsaremainlybasedontheuseofsulfideorenzymeassharpeningagents.Thesulphideunhairingmethodsandenzymeunhairingmethodsareusedinalmostalltheprocessesofleathermanufacture.2.1SulphideUnhairingLime-sulphideunhairingcanbesub-classifiedaspaintu......
Theobjectivesofflue-curingtobaccoaretomaintainandenhancethepotentialqualityembodiedintheharvestedleafandtoprovideanenvironmentconducivetothetransformationofthatleafintoahighqualitycuredtobaccoproduct.Thisisachievedthroughcontrolofthechemicalandbiochemical......
Approximate99%ofalltherawhidesandskinsisfrommammals.Afterslaughtermostmammals,suchasoxen,calves,horses,sheep,goatsandpigs,areflayedbymakingrippingcutsinthebellyandlegs.Theyareoftenhungup,andtheskinsarepeeledoffstartingatthebellyrip,thenthelegsandback.This......
ParticleremovalTwophysicalparametersmustbeconsideredinparticleremoval.Pressuredrop,sometimesreferredtoasresistancetodraw,istheamountofsuctionthatmustbeusedbythesmokertopullsmokethroughthefilter.Thefilter′sresistancetodrawisadditivetothatofthetobaccocolumn......
Inchrometannage,pickledpeltistreatedwithbasicchromesulphate.Eachchromecomplexmoleculereactswithseveralcarboxylgroupsofcollagentoproducecrosslinkingbetweendifferentmoleculechainsofthecollagen.Thiswillstrengthenthefibernetworkofthepickledpeltandconvertthepe......
7.2.1Themanufacturingprincipleofsea-islandfiberThespinningprincipleofunfiguredsea-islandfiberisasfollows.Undercertainconditionstwo(ormore)thermodynamicallyincompatiblepolymerblendtogether,inwhichoneofpolymers(dispersedphase)isdispersedinanotherpolymer(con......
Freshhidesorskinsconsistofwater,proteins,fattymaterials,mineralsaltsandsomeothersubstances.Inalltheseconstituents,theproteinsareimportantforleathermaking.Theseproteinsarecollagen,keratin,aswellaselastin,albumen,globulin,mucins,mucoids,etc.Collagenisthemos......
8.1ConventionalPicklingMethodPicklingreferstothetreatmentofthehidewithsaltandacidtobringtheskintothedesiredpHforeitherpreservationortanning.Attheendofthepicklingoperationtheskinistheoreticallyapurifiednetworkofhideprotein.Thepreviousoperationsofcuring,soa......
Oneextensivestudyoftheeffectoffilterventilationonsmokecomponentdeliverieshasbeenpublished.Thetipsusedrangedinlevelofventilationfrom20%to70%.Itwasshownthatthelevelofventilationremainedessentiallyconstantthroughthesmokingofthecigarettes.Thisfindingcanbeexpl......
6.1TheConceptofWetWhiteProcessThewetwhiteprocesswasfirstrecommendedaslongagoastheearly1980’s.Sinceitsinitialintroductiontotheleatherindustryanumberofchemicalcompanieshavedevelopedmaterialsforuseaswetwhitepretanningagents.Thesematerialshaveallhadthesamegoa......
Wet-blueisacidanddevelopsacidityonstanding.Underacidconditionstheleatherproteiniscationicandthisisfurtheraccentuatedbythemineralretannage.Consequentlynegativelychargedcolloids,suchasvegetabletans,amino-resins,dystuffs,fatliquors,etc.willreadilyprecipitate......
Therearenumerousrawhidedefects(Fig.3)thatmayreducethevalueofthehideandconsequentlyreducethevalueoftheleathermadefromit.Thesedefectsmaybecausedeitherbydiseaseorexternaldamagebeforetheanimalisslaughtered,orbyincorrectflayingoperationafterslaughtering.Inaddi......
