Method for preparing leather through hair-saving unhairing

Abstract

The invention discloses a method for preparing leather through hair-saving unhairing, which mainly comprises the following steps of: (1) soaking in water; (2) protecting hair and unhairing; (3) liming; and (4) washing with water. The method for preparing the leather has the advantages of excellent unhairing effect, short processing time, obvious reduction of wastewater pollutants, recyclable liming solution, and the like.

Description

technical field [0001] The invention belongs to the field of leather processing, and in particular relates to a leather-making method for hair preservation and depilation. Background technique [0002] Liming is an extremely important process in the preparation stage of tanning. The quality of the liming process directly affects the progress of the subsequent process and the quality and performance of the finished leather. According to the research on the degree of pollution in the tanning process, it is found that in the tanning preparation stage, taking cowhide as an example, the BOD value (biological oxygen consumption) is 80% of the entire production stage, and the COD value (chemical oxygen consumption) is 80% of the entire production stage. 70%, the amount of salt is 85%, and the suspended solids are 60%. [0003] Cleaner production is an important strategy for the sustainable development of my country's industry, the direction of industrial production in the 21st cen...

AI Technical Summary

Problems solved by technology

[0004] The traditional liming process mainly uses soda sulfide and lime treatment. This method has many shortcomings, mainly as follows: (1) the use of inorganic sulfur destroys the hair structure, making the hair that comes off bend, agglomerate or become paste, Liming waste liquid is difficult to deal with, and a large amount of fur organic matter is discharged together with chemical materials, resulting in an increase in COD value; (2) Inorganic sulfur can also damage the leather surface, making the leather surface not smooth enough after liming, and affecting the finished leather. (3) the use of inorganic sulfur makes the waste liquid contain S 2- , so it is very easy to produce H2S harmful gas, which will cause harm to the human body. At the same time, the liming waste liquid contains a large amount of sulfide, which is difficult to oxidize and biodegrade. It is usually necessary to add an oxidation process before the waste liquid treatment; The solubility in water is small. In the traditional liming process, in order to maintain the stable alkalinity of the liming liquid, a large amount of lime needs to be used. Due to the poor permeability of the liming liquid, a long liming time is required, the liming efficiency is low, and the lime is easy to settle. , resulting in uneven lime emulsion, resulting in uneven expansion of the gray skin, and some even excessive expansion, resulting in loose leather and obvious gray wrinkles (growth marks); (5) in the liming waste liquid, agglomerated or pasty fur The shedding matter forms a suspend emulsion with a large amount of lime and other additives, which is difficult to settle and separate, and can only be discharged directly. The liming solution cannot be recycled, and it also causes serious damage to the environment while wasting a large amount of water resources and chemicals. pollution