制革概论第二章(英文版)课件

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Chapter 2,Modern Beamhouse Procedures -,soaking,unhairing,and,Liming,2.1,Soaking,1.The purposes of soaking,2.Soaking process:salted hides,fresh hides and dried hides,3.Checking the end of soaking,Chapter 2Modern Beamhouse Pro,1,2.2,Unhairing,1.Unhairing,(,1),HAIR-SAVING,-unhairing system,1-1 Sodium sulfide painting system,1-2 Enzymatic unhairing system,a.Enzymatic painting system,b.Enzymatic drum system,(2),HAIR-BURNING,-,unhairing system,制革概论第二章(英文版)课件,2,2.3,Liming,The purposes of liming,Liming operations,Checking the end of Liming process,2.3 Liming,3,The history of beamhouse,Beam:,The term dates back to the time when the hair was removed from the skins by means of a hand beam using a two-handled knife.Some hand work on the beam is needed occasionally for quality improvement.Such as scud.,The history of beamhouse,4,Beam,Beam,5,Beamhouse,Refers to the process in the tannery between the removal of the skins or hides from storage and their preparation for tanning.,In the opinion of most practical tanners:,Leather is made in the beamhouse,Beamhouse,6,beamhouse,beamhouse,7,制革概论第二章(英文版)课件,8,2.1 SoakingThe first and the most important steps,1.The purpose of soaking,Rehydration,of the hide,Hides and skins,when received by the tannery,are in a condition of preservation based on dehydration.The skins must be wet back and brought to a flaccid condition for subsequent operations.,2.1 SoakingThe first and the,9,Removal,of:,a.,preserving salts,b.dirt and blood,c.unstructured proteins and proteoglycans,Loosen,of,:,a.epidermal structures,b.subcutis,Opening up,the fibres,Preparation,of the hide for the subsequent process,Removal of:,10,2.Conditions of soaking,Disinfectants,The bacteria on hides may be dangerous to man,and bacterial damage to the hides may occur.Chlorinated aromatic compounds may usually be used.,制革概论第二章(英文版)课件,11,Infectious animal diseases:,Anthrax,Hoof and mouth disease,Infectious animal diseases:,12,(2),Temperature,Common,usually 25-28.,The temperature of soaking is different from the different seasons,the areas(Such as in winter,in summer,the southern,the northern and so on).,(2)Temperature,13,Additives,To accelerate the soaking process,Sodium sulfide or sodium tetrasulfide,Add a small quantity of sodium sulfide or sodium tetrasulfide to the soak may result in chemical action on keratin in the follicle,removal of soft globular proteins,.,14,Salt or appropriate alkali,Salt in the soak:aids in the removal of globular proteins and in disinfecting the soak solution,.,Bactericide,Limiting the growth of organisms or killing the bacteria,.,Salt or appropriate alkali,15,Enzymatic soaking/degreasing agent,Surfactant/emulsifier,Enzymatic soaking agents:will further accelerate soaking by use of specific proteolytic preparations to safely digest the non-structured proteins and proteoglycans.For a very fatty raw skin,such as pig,and sheep,choice of degreasing agents(emulsifiers)to remove fat.Deposits of fat will lead to poor penetration of liming agents,and subsequent areas of scud and drawn grain.,Enzymatic soaking/degreasing,16,(4).,Water,Salted hides:,The liquor ratio is such that the quantity of water is low,the salt washed out from the cured hide is generally sufficient to maintain salt concentrations at a proper level for effective,removal of some of the soluble protein.,Dry hides:,Addition of salt will be used to decrease probability of bacterial damage.The goods are fully covered with water.,(4).Water,17,3.Soaking process,The detailed process options,will be introduce in Technology of Leather Making.,Surfactant/emulsifier and suitable enzymatic,soaking agent.,soaking agent and bactericide,will be added to the soaking liquor.,3.Soaking process,18,Wet salted or brined hides,Common temperature 25-28.To remove surface salt,dirt,blood,and manure etc.by washing of 30 minutes.The time of soaking will depend on the type of hide or skin being processing,usually 24-48hours,.,Fresh hides(unsalted),To weaken and remove the non-structured protein(detailed in protein chemistry and Histology)T:25-28.Time:6hours,.,Wet salted or brined hides,19,Dried hides,The fibers of dried hides are too stiff,and mechanical flexing will result in breaking of the fibers.When soaking heavy dried,it may still be necessary to pre-soak the goods overnight in static condition,if they are flexed too early before soak back,extensive damage to the skins can result.Such as loose grain,empty handle,and breaking of the grains.,.,Dried hides,20,Conditions of soaking dried hides,Soaking time,24-48hours.pH:9.5-10,Temperature,25-28.(Depending on using or,not enzymatic soaking agent),Water float,the goods are fully covered.,Vessels,pit,paddle,Drum,Additives,Wetting agents,bactericide,salt,sodium carbonate,and enzymatic,soaking agents.,Operations,Static soaking for 12-24hours,changing the float,the vessel may be turned or revolution each hour.,Conditions of soaking dried hi,21,4.Precautions,To ensure that suffic