皮革入门英语.ppt

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1、2023/3/29,皮革英语入门,1,皮革入门-英语,2023/3/29,皮革英语入门,2,常见的不同动物的皮革,2023/3/29,皮革英语入门,3,皮革在生产各个阶段的名称,未加工前 脱毛前生皮raw hide/raw skin盐腌皮/盐湿皮wet salt hide脱毛后到鞣制前裸皮pelt灰皮limed pelt酸皮pickled pelt蓝湿皮wet blue皮坯crust成品皮finished leather,2023/3/29,皮革英语入门,4,不同鞣制的皮革,2023/3/29,皮革英语入门,5,不同涂饰的皮革,2023/3/29,皮革英语入门,6,皮革各部位名称,2023/3

2、/29,皮革英语入门,7,Wet End Operations水场,Wet End refers to the process from soaking until ready for drying after retaning,dyeing,fatliquoring etc.Normally including the following steps:Pre soak flesh main soakUnhair/lime lime flesh/split relimeDelime bate pickle tan conditionSam split shaving Wash/Wet Back

3、 rechrome neutralize retan dye fatliquor fix,2023/3/29,皮革英语入门,8,SoakingSoaking is to return the raw stock to as near as possible its original condition and remove dirt,blood,bacteria etcMost of the cases,soaking is carried out in drum or paddle,seldom still in pitsIncreased temperature and mechanica

4、l action increases the rate of rehydration,but more chance to get loose leatherThe raw hides are loaded in the drum or paddle,normally less running/more stop at the beginning,Wet End Operations水场,2023/3/29,皮革英语入门,9,SoakingNormally chemiclas used are:Wetting agents/Detergents,Neutral Salt(for Sun dri

5、ed),Bactericide,Alkali salts.Time can take from 4 hours to 2 days depending on the original form of preservation,Wet End Operations水场,2023/3/29,皮革英语入门,10,Wet End Operations水场,Unhairing/LimingUnhairing/Liming is to remove hair and the epidermis and break down and open up the fiber structure of the ra

6、w stock.Normally for hair burning process,unhairing is carried out first then directly followed by liming in the same bath;for hair saving process,hair roots are loosen by certain chemicals then hair was pulled out by mechanical action,then liming is carried out in new bath.For soft leathers,relime

7、is usually carried out after lime splitting or lime fleshing,Unhairing/Liming/Reliming all run with interval stops,2023/3/29,皮革英语入门,11,Wet End Operations水场,Unhairing/LimingChemicals used including:Sodium Sulfide and/or Sodium Hydrosulfide Amines or Anti wrinkle agent Lime AuxiliaryHydrated Lime powd

8、er/pasteDegreasing agentLiming should be gentle and even,uneven swelling occurs leading to wrinkles or drawn grain,lime auxiliary helps for more even swelling and less risk of lime blast.Unhairing/Liming can be carried out with no float,short float,then extended float or long float depending on the

9、raw stock,equipment,etc.,2023/3/29,皮革英语入门,12,Wet End Operations水场,DelimingDeliming is to remove the mechanically deposited and chemically bound lime and of capillary lime by conversion into readily soluble salts.Carried out in drum with continuous runningDeliming is carried out by using acid and/or

10、acid salts:Ammonium Chloride,ammonium Sulphate,Sodium bisulphite,Lactic Acid,boric acid,2023/3/29,皮革英语入门,13,Wet End Operations水场,BatingBating is to break down certain amount of fiber structure and further open up the collagen network.Temperature(30-36oC),pH(8.0-8.5),running time(10-60)and enzyme typ

11、e will decide the effect of bating,which is checked mainly by experience.Most common enzyme is pancreatic enzymes,with continuous running or running for some time then rest some time.The enzyme value(LVU)is the number of enzyme units in 1 g bating agent.One enzyme unit has the fermentative capacity

12、to digest 1.725 mg casein.,2023/3/29,皮革英语入门,14,Wet End Operations水场,PicklingPickling is to acidify the pelts to a certain pH before chrome tannage and thus to reduce the astringency of the chrome tanning agents.Pickling must put in enough salt first(min.6Beo)to prevent unexpected swelling which resu

13、lt in poor tensile strength.Depending on the final pH and the type of acids used,amount of the acid vary from 1%to 3%Usually weak acid prior to strong acid if there has.,2023/3/29,皮革英语入门,15,Wet End Operations水场,PicklingChemicals used:Common SaltWeak acid(Formic Acid,Acetic Acid,Lactic Acid)and/or St

14、rong Acid(Hydrochloric acid,Sulphuric acid)Pickling time can be 30 to over 12 hours(over night)depends on the type of leather etcPickling must be carried out cold to stop unwanted hydrolysis which reduces tensile strength.,2023/3/29,皮革英语入门,16,Wet End Operations水场,TanningTanning is to bring about irr

15、eversible stabilization of the skin substance that is prone to putrefaction.Tanning is carried out with Mineral Tanning agents(such as Chromium Sulphate,Aluminium,Iron or Zirconium etc),Aldehyde,vegtable tannin,synthetic tannin,etc.Chrome tanning known as Wet Blue is most popular as it is fast,effic

16、ient and cost effective.Low pH,Temperature and basicity is used to start with,to allow for penetration and then pH and basicity is raised to fix the Chrome to the fibres.The Leather can now withstand 100oC(TS,Temperature of Shrinking)rather than 40oC for the Raw hide or skin.,2023/3/29,皮革英语入门,17,Wet

17、 End Operations水场,TanningTanning is finished by raising the temperature and pH of the system,by adding sodium formate,sodium bicarbonate,sodium phthalate etc,now more and more tannery using Magnesium Oxide as it is safer,easier handle,better wet blue etc.The final is controlled by pH(3.6-4.0),temper

18、ature(around 40oC),TS(90-110oC)Wet blue need condition for better fixation of chrome.,2023/3/29,皮革英语入门,18,Wet End Operations水场,Sam/Split/ShavingThese mechanical operations are mainly for get the right thickness for final leather.Samming is to get rid of the excess water in the leather and ready for

19、splittingSplitting is to get close thickness of the final leather,separate the grain and split,ready for shavingShaving is to get as precise as possible thickness to the requirement of the final leather,2023/3/29,皮革英语入门,19,Wet End Operations水场,Washing/Wetting BackGet the wet blue ready for later pro

20、cess.Usually using wetting agent/emulsifier,and weak acid with the temperature of 30-40oC.Running time depends on the condition of the wet blue,vary from 20 to a few hours,2023/3/29,皮革英语入门,20,Wet End Operations水场,RechromingRechroming is to increase the chrome content of the wet blue,level up the var

21、iations of each hideRechroming usually carried out after wet back at a pH of 3.3-3.5,finished by increase pH with Sodium formate and/or sodium bicarbonate to a pH of 3.6-4.2Chemicals used here are:Chrome powder,chrome syntanGlutaraldehyde,polymer,amphoteric syntanCationic/stable anionic fatliquorFor

22、 certain wet blue/article,rechrome not always necessary,2023/3/29,皮革英语入门,21,Wet End Operations水场,NeutralizingNeutralizing is to Remove free acids present in mineral tanned leather or formed in the leather during storage.Neutralization is carried out according to the type of leather to be produced.In

23、tensive neutralization throughout the whole cross-section is necessary for penetration of latter chemicals used.Instead of using alkalis,the leathers are in some cases treated only with lightly neutralizing syntans.The mild action donot cause damage to the leather fibre.Overneutralizing should alway

24、s be avoided,as otherwise a coarse loose grain and an empty handle are obtained.,2023/3/29,皮革英语入门,22,Wet End Operations水场,NeutralizingNeutralizing is checked with BCG for the penetration,and pH paper/meter for the pH of the float.Neutralization time is decided by the neutralizing system and the fina

25、l article requirement,can vary from 30 to over night(more than 12 hours).Almost all the leather need certain degree of neutralizing.Chemicals used are:Neutralizing syntan both naphthalene/phenol basedWeak alkali salts sodium formate,acetate,Sodium sulphite，Sodium thiosulphateStrong alkali salts sodi

26、um bicarbonate,ammonium bicarbonate,2023/3/29,皮革英语入门,23,Wet End Operations水场,Retanning/DyeingRetanning/Dyeing is to give the final leather proper body/handle,physical property and expected color.Usually retaning and dyeing is carried out in the same float,started with short float of 30-50%ended with

27、 adding hot water which help fixation,and fixed with formic acid to a pH of 3.8-4.2The amount of retanning agents/dyestuffs is decided by the final leather requirement and the wet blue,2023/3/29,皮革英语入门,24,Wet End Operations水场,Retanning/DyeingThe time of retanning in most cases is less than 5 hours,d

28、epends on the chemicals and article requirement Retanning is a complex step and using quite a few kinds of different chemicals which they all have different functions and effect on wet blue.Chemicals used in this step are:Polymers,eg.Acrylic,styrene-maleic copolymer,Resins,eg.Urea formaldehyde,Dicya

29、ndiamide,melamine,Syntans,eg.Phenolic,naphthalene and sulphone based,Vegetable,eg.Quebrocho,mimosa,chestnut,gambier,taraOther retanning agents:aldehyde,oil,protein filler,2023/3/29,皮革英语入门,25,Wet End Operations水场,FatliquoringFatliquoring is to lubricate the leather fiber to give leathers the desirabl

30、e softness and handle.At the same time,influences the physical properties of the leather,such as extensibility,tensile strength,wetting properties,waterproofness and permeability to air and water vapour.Fatliquoring most of the time is carried out at a high temperature of 50-60oC,fatliquor is pre em

31、ulsified with hot water of 50-60oC before adding in the drum,running time between 30-90,finished by adding acid to precipitate the fatliquor in the emulsion.,2023/3/29,皮革英语入门,26,Wet End Operations水场,FatliquoringFatliquor can be made from:Natural oil/fat/wax:Vegetable oil/fat/wax:castor oil,nut oil,A

32、nimal oil/fat/wax:fish,lard,neatsfoot,wool greaseSynthetic oil/fat/waxParaffin waxes,mineral oils,olefins,processed hydrocarbons,synthetic fatty acid esters and waxes,fatty alcohols,alkyl benzenes.The chemistry of processing fatliquor can be roughly divided in the following:Sulphated,sulphited,phosp

33、hated,sulphonated,2023/3/29,皮革英语入门,27,Wet End Operations水场,FatliquoringMost of the cases,Fatliquoring is using a mixture of several different type of oils,this and the amount of fatliquor mainly depends on the property of the oils,final requirements and some personal preference.Retanning agents eg.P

34、rotein filler,polyacrylic,can be used in fatliquoring to improve the property of the leather such as tightness,fullness,Improper use of fatliquors can lead to loose leather,oil patches,spew,etc problems,2023/3/29,皮革英语入门,28,Wet End Operations水场,FixingFixation as the final step of wet end process,norm

35、ally carried out with formic acid.Cationic products like mineral salt(chrome,aluminium),amine salts,etc also used for fixing to improve color fastness,washable property,etc.After all the wet end process,a cold wash and minimum 4 hours rest(usually over night)is necessary to let the reaction and dist

36、ribution of the chemicals complete.,2023/3/29,皮革英语入门,29,Wet End Operations水场,Wet End MachineryDrum/paddleFleshing machineLime splitting machineSamming machineSplitting machineShaving machine,2023/3/29,皮革英语入门,30,Wet End Operations水场,Wet End MachineryDrum/paddle,2023/3/29,皮革英语入门,31,Wet End Operations水

37、场,Wet End MachineryFleshing machine,2023/3/29,皮革英语入门,32,Wet End Operations水场,Wet End MachinerySplitting machine,2023/3/29,皮革英语入门,33,Wet End Operations水场,Wet End MachinerySamming machine,2023/3/29,皮革英语入门,34,Wet End Operations水场,Wet End MachineryShaving machine,2023/3/29,皮革英语入门,35,Drying Process干燥,Dry

38、ing processDrying is to remove water from the retanned stock,and get ready to latter finishing processDifferent drying method have their own advantage and can be combined to get expected result:Hang dry gives softer leather with a raised grain and less yieldVacuum drying sets the grain flat,allows r

39、emoval of water at lower temperatures and minimal area lossPaste drying gives a high efficiency,minimal area loss,but paste has to be removed so useful only for Corrected grain types or Nubucks and SuedesToggle drying gives better yield but looser leather,Infrared/high frequency drying gives high yi

40、eld but a rather empty leather but popular in high labour cost countries like Italy.,2023/3/29,皮革英语入门,36,Drying Process干燥,Drying processAfter drying,the moisture content of the crust will be between 10-15%，condition is to adjust the moisture content to be around 20%by spray water on the fleshStaking

41、 to soften the leather,usually conditioning with water is necessary first for best results.Trimming after dry toggle is to get rid of the parts which is no more usableBuffing to remove damaged grain and defects or improve the nap on Nubucks and suedes.Airblast or dusting to remove unwanted dust,brus

42、hing builds up static electricity and retains dust,the use of air blows it away.,2023/3/29,皮革英语入门,37,Drying Process干燥,Drying MachinerySet out machineVacuum Drying tunnel/lineDry milling drumToggling machineBuffing machineAirblast,2023/3/29,皮革英语入门,38,Finishing Process涂饰,Finishing is more art than tec

43、hnique Finishing is to improve physicals,cover defects,improve aesthetics,add colour and shine etc.Good result depends on the crust,chemicals,equipment and the finisherCertain mistakes made in the wet end processing can be corrected in Finishing,Leather quality can be upgraded by careful finishing.I

44、n general,a finish is built up of several coats starting at the bottom being very soft and flexible,and at the top hard and scuff resistant.,2023/3/29,皮革英语入门,39,Finishing Process涂饰,Normal finishing process,Spray or Through feed dyeing with Dyes,water,solvent/penetrator,to correct or level color of c

45、rust.Impregnation With fine particle resin,water and penetrator to tighten the grain and give a smooth surface.Base coat consists of pigments,resins,fillers etc to ensure good adhesion and all round physicals of the finish.Pigment or colour coat is used to level out the colour,and improve further th

46、e all round physical properties.Top coat determines the final appearance,handle of the final leather,also the physical properties required,2023/3/29,皮革英语入门,40,Finishing Process涂饰,Method of application Padding,Brushing or SpongingSpraying(compressed air,airless,or air mix)Curtain coating(slot or over

47、flow curtain coating machine)Roller coating(application by roller machine)Printing(Gravure roller printing system)Laminating(bonding of films e.g Relca Coater system)Coating(film formation over moulds),2023/3/29,皮革英语入门,41,Finishing Process涂饰,Recent environmental pressure Reduction of Formaldehyde le

48、vels Reduction of Phthalates and Nonylphenol ethoxylates(plasticiser in NC lacquers)Reduction of heavy metals(Mainly pigments)Restriction on short chain chlorinated paraffinNMPIncreasingly higher physicals,2023/3/29,皮革英语入门,42,Finishing Process涂饰,Finishing ChemicalsColorantsPigmentCasein Free/CaseinC

49、ationic/Anionic/NonionicOrganic/InorganicSpray DyeWater soluble/Solvent Soluble/water&solvent solubleBinders Film formingThermoplasticButadiene,Polyacrylic,Polyurethane Non-thermoplasticCasein/protein/polyamide,NC/CAB Lacquer,2023/3/29,皮革英语入门,43,Finishing Process涂饰,Finishing Chemicals CarrierWater/S

50、olventAuxiliariesFillerOrganic Filler/Inorganic Filler/Wax FillerCrosslinkerAziridine/Polyisocyanate/epoxideDullerPenetratorModifierThickener/Leveler/Feeling agent,2023/3/29,皮革英语入门,44,Finishing Process涂饰,Developing FinishingOnce a type of Finish has been decided,the finish can be formulated.For a ba