Related leather terms and basic concepts

Related leather terms and basic concepts

1. Leather and leather

The skin peeled from animal body is called "raw skin", which is the raw material of leather industry. After a series of physical and chemical processing, raw hide has changed its nature and appearance to meet people's different needs. This kind of raw leather without hair is called "leather" for short.

The raw leather of super fiber synthetic leather without tanning has the following properties:

(1) The skin peeled from an animal is wet; After drying, it becomes hard and loses its flexibility and flexibility. It is easy to break when bending.

(2) Wet state of the raw skin in hot and humid temperature conditions, will be very fast decay, hair loss, odor.

(3) The higher the temperature, the greater the degree of shrinkage.

(4) The air permeability and vapor permeability of raw hide are not good, that is, the hygiene is not good.

(5) Under the action of chemical drugs, the raw skin is easy to be destroyed.

Because of the above properties, raw skin can not be directly made into household products for people to use.

Leather after physical and chemical processing has different properties:

(1) Leather does not become hard and brittle material, it maintains the curvature and availability. According to the requirements of the application, the appropriate processing method can be selected to obtain the required degree of soft and hard and proper extension.

(2) Leather does not rot ≥ even after drying, it will not decay again.

(3) The temperature of leather shrinkage in hot water is above 65 ℃, and some leather does not shrink in boiling water.

(4) The permeability and permeability of leather are better than that of raw leather.

(5) Leather has stronger chemical resistance than raw leather.

Because of the above properties, leather can be made into products suitable for people's life and production.

2. tanning and tanning agent

Tannin refers to the pure substance which can be combined with the white matter of the raw skin and make it into leather. The industrial products of tanning are called "tanning agents". There are many kinds of tanning agents, which can be divided into two categories: inorganic tanning agent and organic tanning agent.

(1) The inorganic tanning agent is mainly trivalent alkaline chromium salt, followed by trivalent aluminum salt, trivalent alkaline iron salt, tetravalent alkali zirconium salt, tetravalent alkaline titanium salt, silicate, phosphate, etc.

(2) Organic tanning agents include plant tanning agent, synthetic tanning agent, resin tanning agent, aldehyde tanning agent, oil tanning agent, etc.

The process of processing and disposing raw skin with tanning agent is called tanning. The whole process of leather making is called leather making, which is based on the systematic chemical treatment of raw leather and proper machining. That is to say, tanning is only the process of transforming raw skin into leather. Besides tanning, the root making includes preparation before tanning and finishing after tanning, making it a commodity.