Leather Waste &Nbsp: New Materials Obtained By Functional Materials

China's leather industry produces a large number of waste collagen materials every year as a high input and low output.

Significance of skin collagen waste utilization

According to academician Shi Bi, a National Engineering Laboratory of leather cleaning technology, Sichuan University, leather industry has been facing severe challenges of sustainable development since the 90s of last century. The utilization of leather waste has gradually become an important research topic of common concern at home and abroad. The economic and social significance of recycling and utilization of leather waste is becoming increasingly prominent.

Most of tannery wastes are leftover materials, and more than 80% of them are collagen. They are not only rich sources of protein and amino acids, but also excellent functional biopolymers.

Because of its unique biological characteristics, tannery wastes have broad application prospects in many fields, such as medicine, food, functional health products, cosmetics, agriculture and so on.

Recycling and making full use of these solid wastes and waste leather products can not only provide a large number of new industrial materials, reduce the damage to the ecological environment, but also facilitate the long-term development of leather industry.

Great potential for developing functional materials

A large number of waste dandruff produced during tanning process has great potential in the preparation of new functional materials. It is a valuable two resource.

Academician Shi Bi said that hundreds of collagen molecules were connected and assembled laterally, forming a collagen fiber, a water-soluble natural polymer material.

This material is rich in peptide, carboxyl, hydroxyl, amino and other active groups, which lays the foundation for the preparation of various functional materials.

The research group led by academician Shi Bi has done a lot of research in this field.

They found that plant tannins, which are widely distributed in many traditional Chinese medicine and plant drinks, may have negative effects on human health. The effect of skin collagen material on plant tannin adsorption is obvious. It is difficult to remove or recover heavy metals from water bodies. The tannin material that can remove or recover heavy metals can be obtained by tannin aldehyde tanning reaction. With the flexible "tanning" principle in leather making, the metal ions materials can be prepared by using waste collagen as the carrier. The collagen fibers are highly ordered assembled from collagen molecules and are ideal raw materials for preparing inorganic functional materials. The conductive fiber materials made from waste collagen have strong absorption properties for radar waves.

The rich and colorful scientific principles of leather making provide abundant imagination for the use of waste collagen to create new functional materials.

The key technology project of solid waste recycling and utilization, completed by Shandong Light Industries College, has developed new leather tanning agents, multifunctional leather tanning agents, amphoteric calcium carbonate fillers, collagen mask paper and filamentous leather products for the treatment of chromium containing and non chromium containing wastes, collagen and non fibrosis utilization. It has expanded the application scope of collagen fibers, is conducive to the implementation of leather cleaning technology, and promotes the sustainable development of leather and paper industry.

Improving the added value by modifying technology

Ding Zhiwen, Professor of China leather and footwear industry research institute, said that the collagen extracted from leather waste is difficult to be used as raw material for food and cosmetics with high added value because of its hygienic properties. There is also a problem of low added value as raw material for feedstuffs. However, as industrial raw materials, there is basically no such problem. It can also give full play to the hydrophilic and moisturizing properties of collagen structure, and increase the added value of leather waste.

However, collagen has unique advantages, but it can not be widely used as industrial raw material.

For example, although it has the advantages of good hand feel and moisture permeability, it has poor water resistance. It has good affinity for leather retanning filling material, but its binding property is not good.

Therefore, it is necessary to modify the collagen specifically, effectively avoiding the shortcomings of collagen, so as to meet the requirements of various industrial uses for collagen.

At present, the modification of collagen can be summarized into three categories: cross-linking modification, modification of active groups and introduction of polymer modification. Modified products are used as leather tanning agents, filling agents, chrome tanning AIDS, finishing agents, retanning agents and so on. For example, polyurethane has good mechanical properties, corrosion resistance, flexility, flexibility and elasticity, and its modification of collagen can improve the weakness of collagen material's hardness and water resistance. At the same time, the moisture absorption property of collagen material can also improve the poor moisture permeability of polyurethane.