Reuse Value Of Leather Waste Resources

Leather waste, generally refers to the main component of the waste collagen structure. There are many kinds of leather waste, which can be divided into tannery waste, leather waste and waste leather products.

1. Chromium free. Leatherwear waste

For example, fur waste, gray leather waste and leather waste, because of the relatively simple composition, it is easier to use.

2. Chrome containing leather waste

For example, shaving, leather and rim waste of wet blue leather are difficult to use because of the presence of chromium salts.

3. Leather waste containing dyestuff

For example, dry cutting and rim waste, leather cutting and other materials, as well as other materials, such as dyes, fatliquors and retanning agents, are the most difficult to make use of.

The utilization of leather waste is an old topic. In 1928, Italians first used chrome containing leather waste as raw material for artificial leather. However, due to the harm of chromium, applications are subject to certain restrictions. At present, the main application area is the production of non-woven fabrics, artificial leather and other composite materials based on its fiber characteristics, or the manufacture of composite materials with other fibers. Chromium is not used rationally, the added value of products is not high, and some of them are used as fertilizers and feedstuff. Another part of it has to be buried because it can not be used rationally. Seek The rational and effective way of utilizing and developing high value-added products has become an important topic in the utilization of leather waste.

1, raw feed development

Through the technology of high pressure, cooking and sterilization, the raw leather can produce a brown yellow meat bone meal. Compared with the previous feed, the pet feed prepared from this meat bone meal has not only high nutritional value, but also great economic benefits.

2. Organic fertilizer

Leather waste contains a large amount of "nitrogen", which can be produced by calcination to produce agricultural fertilizers, so as to meet the production of crops and increase the yield of wheat and rice.

3. Hair utilization

In tannery production, the wool that can be recovered and utilized mainly includes sheep wool and goat hair. Besides the direct recovery, the development and utilization of wool also include: degradation of wool, isolation and purification of degradation products, etc. it can be used in the following aspects: biological fermentation and soil conditioner, and chemical degradation of protein polypeptides.

4, meat residue utilization

The residue from raw material after soaking and removing meat is a raw material that can not be neglected for oil recovery. After the meat is washed and boiled, the oil is floating on the liquid surface, and the oil can be collected from the liquid surface. The saponification value of these recovered oils is generally 190-210, which can be used for the production of high-grade oils and fats, glycerin and so on. In the tanning industry, these oils are often sulfated or sulfated and used for leather fatliquoring.

Without chrome containing leather waste, because it does not contain harmful substances such as chromium salts, it is easy to obtain high purity collagen products through pretreatment and hydrolysis, such as eating gelatin, edible collagen, regenerated collagen skin, collagen for medical and cosmetic products, etc. With the increasing number of pet dogs, the market demand for dog chewing gum is increasing. The leather waste can be regenerated into a regenerated collagen skin with controllable area and thickness without adding adhesives and other harmful substances. Moreover, the cutting waste produced in the production of dog bites can also be reused to prepare regenerated dog skin, which not only expands the range of raw materials for dog bites, but also greatly reduces production costs.

1. The hydrolysis mechanism and recycling method of chrome containing leather waste to extract collagen.

Under the condition of strong hydrolysis, chrome containing leather wastes are partly broken by the amide bonds on collagen polypeptide chains, resulting in the formation of water-soluble collagen. There are two main applications of the hydrolytic mechanism of chrome containing leather waste, which is to increase the gelatin extraction rate and reduce the chromium content in the collagen obtained from chrome containing leather waste.

2. Recycling of chromium. Leatherwear Collagen in waste materials

Chromium containing leather waste is hydrolyzed to obtain chromium mud. After two times hydrolysis, the chromium mud is obtained with 1 filtrate and chromium cake. After washing the chromium cake, 2 of the filtrate is obtained, and the filtrate is 1 and 2. The collagen hydrolysate is obtained, and the hydrolysate is used instead of the water to recycle the chromium containing leather waste, so that a high concentration of collagen solution can be obtained.

3, series of collagen based leather chemicals

(1) preparation of retanning agent from collagen modified by acrylic acid monomer graft

The application of this kind of Retanning Agent on leather making can obviously improve the effect and elasticity of leather products. Moreover, the handle is soft and plump, leather thickening reaches 20%, and the area shrinkage is less than 10%.

(2) amino resin modified collagen filler.

Collagen filler should be used in leather making process with obvious selective filling effect. Moreover, because the filler has the amphoteric structure of collagen, retanning will not cause the phenomenon of "fading color" of the green leather. At the same time, the handle is natural, comfortable, soft and plastic free.

(3) acrylic resin modified collagen finishing agent

Compared with pure acrylic resin finishing agent, the modified collagen finishing agent has good covering effect, comfortable feeling, no plastic feeling, and good solvent resistance.

(4) polyurethane modified collagen finishing agent

The application of the coating shows that the polyurethane structure can greatly improve the film formation performance of collagen, and the handle feels comfortable and no plastic.

(5) preparation of chrome tanning agent from chromium residue

The experimental results show that when the amount of dichromate is more than 4 times of chromium content in chromium residue, the chrome tanning agent obtained is not significantly different from the chrome tanning agent purified from pure dichromate.

4, collagen composite fiber

Protein fiber is made of natural protein as the main raw material, through modification and blending with other materials, making a certain concentration and viscosity of the solution, and then extruded from the spinning hole to enter the solidified liquid to form filaments. After subsequent drying and stretching treatment, it can get the fibers that can be used for spinning. The protein fiber has glossy silk, soft and comfortable handle, good moisture absorption and excellent dyeing property.

1. Leather dyeing filler

Dyeing leather waste is used to make leather dyeing filler. It has good filling effect. The amino resin modified in the dyeing filler, the retanning agent dissolved in the waste material, and the collagens combined with the retanning agent have good filling effect. The dye contained in dyeing filler can play the role of dyeing, and reduce the 10-30% of dyestuff consumption in tannery production process, thus saving production costs.

2. Superfine grinding and application of dyed leather waste

Leather waste is a tough material. After crushing and embrittlement, it can improve its comminution performance. The superfine leather powder can be obtained by ultrafine grinding. The ultra-fine leather powder mixed with polyurethane slurry is applied in wet film transfer between synthetic leather and two layer leather. Leather components can be introduced into synthetic leather to improve moisture absorption and moisture permeability and feel of synthetic leather and two layer leather wet film.

China's leather industry produces a large number of waste collagen materials every year. As a high input and low output traditional industry, 30% of the raw materials in the tanning industry eventually become waste materials. In recent years, about 1 million 400 thousand tons of leather waste has been produced in China in recent years. The pollution of the environment has also resulted in a great loss of collagen and chromium oxide, resulting in a huge waste of biomass resources. Most of the leather waste is leftover leftover materials. More than 80% of them are collagen, which is not only a rich source of protein and amino acids, but also an excellent functional biopolymer. Because of its unique biological characteristics, tannery wastes have broad application prospects in many fields, such as medicine, food, functional health products, 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.