Distinction And Characteristics Of Leather Raw Materials For Leather Making

There are many kinds of raw materials for leather making and fur making, especially the varieties of fur raw materials.

Looking at the leather industry in the world, the main raw materials are cowhide, sheepskin and pigskin, as well as some other leather.

First, cowhide.

The total number of livestock in the world is around 1 billion 435 million in 1997. The annual slaughtering rate is about 15%~25%. The difference is very large among different countries. It has about 300 million head, and the annual output of cowhide is about 100 thousand tons, which has increased in recent years.

Cowhide includes cattle hide, buffalo hide and other cattle skin.

Cowhide covers about 2/3 (65%~70%) of the world's total leather output, of which 67% is used for leather shoes, 33% for processing clothing, leather goods and furniture. In recent years, the use of cowhide for processing automobile upholstery leather has increased trend.

Cowhide is the most important raw material resource for leather industry in the world.

Our country produces about 12 million pieces of cowhide annually.

(1) species

There are more kinds of cattle skin, such as cow skin, meat, cattle hide, cattle hide, cow hide, Bull Hide, Uncastrated Bull Hide and castrated bull skin.

There are also cattle hide, buffalo skin, yak skin and calf skin in China.

They can be made into almost all kinds of leather products according to the situation and needs of raw materials.

The type, origin, age, sex, feeding status and way, climate, size, thickness, weight level, fat content, sweat glands, blood vessels and thick consistency of the cowhide directly determine the texture of the cowhide, and thus affect the application value of the cowhide and the properties of the leather made.

The thickness of cattle skins slaughtered by cattle is different from that of cattle. It is generally about 3~12mm. The leather used in leather making is thicker than that of the loose nipple. The thickness of the leather is about 10%~20%, which is about 70%~80. The epidermis is about 0.5%~1%, and the subcutaneous tissue is about 5%~10% of the skin thickness. The latter two are all removed in the processing of leather making water.

The area is different from the place of origin and age and so on between 2.0~5.5 square meters.

Calf skin is similar to ordinary cowhide, but has more detailed fiber weaving and construction.

The total thickness of raw skins is about 1.5~3.5mm, of which the papillary layer is about 25%~30%, the reticular layer is about 50%~60%, the surface layer is about 1%, and the subcutaneous tissue layer is 10%~20%.

With the improvement of raising, that is, the raising of fat, the fat content in cattle hide is also increasing.

Because calf skin has very small pores and tight grain, it can be used to produce very fine grain leather.

The smaller the calf, the thinner the leather.

But calfskin processing is more difficult than cowhide, mainly trying to open the pattern, and the calf skin is limited.

Calf skin is mainly used for making bright, fine grain upper quality upper leather.

Buffalo skin mainly comes from Indonesia and most parts of South and central China.

Buffalo hide is thicker, thinly hairy and coarsely granular than the cowhide. The surface is thicker, but the local collagen fibers are loosely woven.

Generally, buffalo skin is made into industrial leather, such as leather and shoe upper leather. In recent years, it has been used for making furniture leather (such as sofa leather, upholstery leather, mat leather, etc.).

Two, sheep skin

The total number of sheep in the world is about 12 million, with an annual slaughter rate of 25%~45%.

In 1996, the number of sheep and goats in China was estimated to be 260 million.

Sheep leather accounts for about 10%~12% of the total leather output.

In addition to leather making, sheep skins are also used for making fur and fur leather.

(1) species

Sheep skins include sheep, crossbred sheep and fine wool sheep.

Generally, leather is used to breed sheep or crossbred sheep.

Native sheep skin is the best material for leather making.

Sheep skin can be made into garment leather, written wrapper leather, glove leather and lining leather. The sheep skin with firm structure can be made into shoe upper leather.

Most sheep and goats and fine wool sheepskin are used to make fur.

(two) the characteristics of organizational structure

The main purpose of raising sheep is to get hair and meat.

In general, the more finer the wool of the wool and the looser the plate structure, the lower the value of the leather.

Sheepskin is about 1~3mm thick, and there are a lot of sweat glands and deep follicles in the skin. The nipple layer takes up 40%~60% of the dermis, the net layer accounts for about 25%~40%, the sheep skin contains more fat cells, and has more developed subcutaneous tissue, which is rich in fat. Sheep's skin contains about 30% of the tare.

Because of its loose tissue structure, leather made of leather has a more comfortable handle, but its strength is relatively low.

The lamb skin has similar structure but has a more detailed and compact structure.

The average area of sheep skin is about 0.4~0.9 square meters, and the lambs skin is about 0.3~0.7 square meters.

Three, goat skin

The number of goats in the world is about 600 million, and the annual slaughter rate is about 20%~40%, accounting for 8%~10% of the total leather output.

China's goat skin is rich in resources, annual output of about 30 million, of which Sichuan road and Hankou road goat skin is the best quality.

Goatskin can be used to make various kinds of leather in leather making, including high-grade leather such as polishing shoe upper leather, and also can be made into durable clothing leather, written leather, garment leather and shoe lining leather.

Fine leather gloves can also be made from goat skin.

The quality of goat skin varies greatly with sheep species, producing areas, age and feeding conditions.

It has a higher fastness than sheep leather.

In the thickness of goat skin, the nipple is about 30%~40% and the net layer is about 40%~50%.

The two layers are more closely linked with soft sheepskin.

Because of the less fat glands and sweat glands in the skin, the sickle shaped pores of the skin form the unique appearance of the goat skin.

The sheepskin usually has a detailed fiber weaving state and fine grain.

Goats skin area is 0.5~0.9 square meters, and the goat skin is about 0.2~0.5 square meters.

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Four. Pigskin

The number of pigs in the world is about 800 million, and the annual slaughter rate is nearly 100%. Pigskin leather accounts for about 3%~5% of leather.

Artificial reared pigskin is used for making upper leather, garment leather, bag leather, shoe lining leather and bottom leather.

China has the largest output of pig skin in the world, and the quality of pig leather is also the highest proportion of leather products in the world.

Pig leather and its products are mainly exported to Europe and the United States and other countries and regions.

In addition to the pig skins that are raised by artificial pigs, there are also wild boar skins, the famous wild boar of South America, also known as PEKALI.

This boar skin has obvious pores and grain characteristics of pig skin. Because of its special collagen fiber structure, it can be made into very soft garment leather or glove leather, and the value is very high.

Pigskin has no reticular structure compared with other mammalian skins.

The papillary layer is 80%~90% of all skin thickness, about 10%~20% of subcutaneous tissue, and consists of adipose connective tissue and muscle.

In addition, pigskin contains high fat content, which accounts for about 20%-30% of tare.

The location difference is large, and the thickness difference is as high as 1: (3~5).

The pores are thick and shaped like "products", thus forming the unique characteristics of pig skin.

Because of the disadvantages of coarse and large parts of pig skin, pig species have been improved, such as lean pigs with smaller parts and smaller grain size.

Besides, the quality of pigskin in different areas and pig breeds in China is not only large in yield but also good in quality.

In other areas, especially the northern pig skin, the pores are thick, the positions are poor, the quality is poor, and the stripping rate is low.

The area of pigskin is generally 0.7~1.3 square meters.

Five. Horse hide

Horses feed around 66 million horses worldwide.

There are different kinds of domesticated horses and wild horses.

Compared with cattle skin, horse hide has a loose nipple.

The biggest feature of horse hide is its very tight and firm skin.

Leather is difficult to handle, and is usually made into solid base leather or special industrial leather.

Our country has studied and solved the problem of leather processing and applied for a patent.

Other parts of horse hide can be used to make garment leather, shoe upper leather, sofa leather, etc.

Six. Reptile skins

Reptiles are mainly distributed in the equatorial region of the earth.

The protection of wild animals should be considered in processing.

Reptile leather accounts for less than 0.2% of leather output.

There are crocodile skin, short nosed crocodile skin, lizard skin, snake skin, bullfrog skin and so on.

The surface of crocodile skin is composed of cuticles which are not particularly variable.

The longer the growth of crocodile skin, the harder and more prominent the cuticle on the surface.

The crocodile skin has only two dimensional fiber braid, so it becomes smaller in elasticity and is not easy to make leather with good handle.

But the advantage of this kind of leather is good shape and special appearance.

Therefore, crocodile leather is of high value.

Crocodile skin belly leather is mostly used for leather bags, leather shoes and so on.

A small number of crocodile skins with obvious horny "scales" are used for wall decoration.

In short, alligator skin is a rare and valuable leather.

Lizards and snakespeare have different grain and grain characteristics due to their variety.

Generally, they are attached with "scales" and are made of leather with beautiful three-dimensional grain pattern.

For lizard skin or snake skin, which has its own color and beautiful pattern, measures can be taken to preserve its beautiful grain color.

Snake skin is thinner and its strength is lower. It is generally used for bags, shoes decoration or advanced waistbands, and the surface of watchband.

The skin of bullfrog is unique because of its interesting dots.

Now more bullfrog is raised in some areas of China, which is also a kind of resource that can be used.

Seven. Fish skin

Fish leather is very small in the world, accounting for only 0.1% of the total.

Sea fish skin has shark skin, cod skin, fish skin, eel skin and so on. Freshwater fish skin has scaly skin like grass carp and carp skin.

Most fish skins have scales, and the scales are removed after leather processing, leaving a "scale nest" on the leather surface, so that the fish leather has a special three-dimensional appearance.

Fish skin is characterized by "layered" braided structure, and the links between layers are weak. Therefore, if the meat is overdone, it is easy to thin the netted layer of fish skin.

Many fish skin varieties are sensitive to high temperature and high concentration chemicals, which easily lead to excessive protein hydrolysis.

There are few resources of sea fish skin in China, but freshwater fish culture is large and widely distributed. It can make use of fresh fish skin (such as grass carp) to make leather with special appearance.

Fish skin can be used for decorating, decorating and decorating leather shoes.

Eight. Other kinds of leather

It accounts for less than 1% of the total leather, including deer skin, antelope skin, camel skin, kangaroo skin, ostrich skin, EMU skin and so on.

1. The structure of deer skin is similar to sheepskin. It is used to make soft garment leather, oil tanning wipe leather, aviation kerosene filter leather and so on.

2. Camel skin can be used to make shoe upper leather.

3. Kangaroo skin is mainly produced in Australia with fine grain and can be made into packaging leather and upper leather.

4, ostrich skin is mainly produced in Africa and other places. Now all over the world have been reared artificially, and the amount of raising is also large in China. It is estimated that there will be 100 thousand stripping and stripping each year, and the amount of breeding and stripping will gradually increase.

Ostrich has larger skin (about 0.8~1.2 square meters).

After the big feather is removed, the "pore cap" is left behind, which makes the ostrich skin a rare and rare variety.

Ostrich leather is mostly processed into high-grade packaging or used for decorative decoration of leather shoes.

The ostrich claw skin has a very beautiful appearance and can be used for making high-grade leather shoes or belts.

5, EMU skin is similar to ostrich skin, but the width is smaller (about 0.3~0.5 square meters), its pore characteristics are not as prominent as ostrich skin, and its effect is obvious. It can be processed into glove leather, garment leather and so on.

Other kinds of bark include dog skin and rabbit skin.

In short, the raw materials used for leather making are three kinds of leather, such as cattle, sheep and pig skins, while other rare species have a certain share in the leather market because of their unique appearance, but the quantity is generally less and the price is higher.

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Types and distinction of leather

Modern leather processing technology is more and more advanced and leather varieties are more and more. It is far from enough to distinguish the authenticity from the thickness and density of leather surface.

Knowledge of leather and knowledge of leather properties and strength will help greatly in the design and manufacture of leather products, the purchase and use of leather products for leather products.

The leather industry in the world includes leather, regenerated leather and artificial leather.

1. Genuine leather is raw material that is stripped from cattle, sheep, pigs, horses, deer or some other animals. After tanning and processing, leather is made of leather materials with various properties, strength, touch, color and pattern. It is a necessary material for modern leather products.

Among them, cowhide, sheepskin and pigskin are three kinds of leather materials used for leather making.

The dermis is divided into two types: head skin and two skin.

(1) the skin of the first layer is a cattle, sheep and pig skin with grain. There are natural scar and blood tendon marks on the surface. Occasionally, there are knife injuries in the processing process and very low belly parts.

The whole grain of the skin can be distinguished from the animal skins from the size and density of the pores.

There are more kinds of cattle skin, such as cow skin, meat, cattle hide, cattle hide, cow hide, Bull Hide, Uncastrated Bull Hide and castrated bull skin.

There are also cattle hide, buffalo skin, yak skin and calf skin in China.

Among them, the pores of the buffalo hide are thicker and thinner, while the yellow cattle hide is smaller and thicker than that of the buffalo hide.

The pores of sheep skin are thinner, denser and slightly skewness, mainly consisting of two main categories: sheep skin and goat skin.

Pigskin's rule of long hair is a small number of 3~5 roots, so it is easy to distinguish. It is easy to distinguish. Pigskin is commonly used for raising pigs, and wild boar skins. The famous wild boar is wild boar. The boar skin has obvious porcine skin pores and grain characteristics. Because of its special collagen fiber structure, it can be made into very soft garment leather or glove leather, and its value is very high.

In addition, ostrich skin, crocodile skin, short nosed crocodile skin, lizard skin, snake skin, bullfrog skin, sea fish skin (shark skin, cod skin, fish skin, eel skin, pearl fish skin, etc.), freshwater fish skin (with grass carp, carp skin and other scaly skin), fur fur fox fur (Yin Hu skin, blue fox skin, etc.), wolf skin, dog skin, rabbit skin and so on are easy to identify, and can not be made of two layers of skin.

The skin of the first layer is made directly from the raw skins of various animals, or the skins of cattle, pigs, horses and other animal skins with thicker cortex are sliced and cut into two layers.

(2) the two layer skin is the two layer of loosely woven fibrous tissue. It is processed by chemical material spraying or covered with PVC and PU film.

Therefore, the effective way to distinguish the skin of the head and the two layer skin is to observe the fiber density of the longitudinal section of the skin.

The skin of the first layer is composed of a dense thin fibrous layer and a slightly loose overlayer which is closely connected with it. It has good strength, elasticity and process plasticity.

The two layer of leather is only a loose fibrous tissue layer. It can only be used for making leather products only after spraying chemical raw materials or polishing. It maintains certain natural elasticity and process plasticity, but its strength is poor, and its thickness is the same as that of the head skin.

2, regenerated skin: after crushing all kinds of animal skins and leather waste, chemical raw materials are processed and made.

Its surface processing technology is the same as leather surface and embossed leather. It is characterized by its neat edge, high utilization rate and low price. However, the skin is generally thicker and its strength is poor. It is only suitable for making the products of price, such as price document box, pull rod bag, club sleeve and so on. The structure of its longitudinal section is uniform and uniform, and the solidification effect of liquid mixed fiber can be identified.

3, artificial leather: also known as imitation leather or rubber, is the general name of man-made materials such as PVC and PU.

It is made on the basis of textile fabric or non-woven fabric, and is made by foaming or laminating of various formulations such as PVC and PU. It can be made according to the requirements of different strength, wearability, cold resistance, color, luster, pattern and pattern. It has many characteristics, such as a wide variety of colors, good waterproofing, neat edges, high utilization rate and relatively low price, but most of the artificial leather can not reach the dermis effect with its elasticity and elasticity. Its longitudinal section can see tiny bubble holes, cloth or surface film and dry dry man-made fibers.

It is a very popular material from the early stage until now. It is widely used to produce various leather products or some of the genuine leather materials.

Its increasingly advanced manufacturing process is being widely used in the manufacture of two layers of leather.

Nowadays, the leather like leather with the characteristics of leather has been produced, and its surface technology is almost the same as that of domestic leather.