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The Key Technology Of Producing Sheepskin Half Shoe Upper Leather

2008/8/8 15:48:00 41785

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In recent years, a sheep leather with a style between garment leather and shoe upper leather has been popular in the market. We call it "half shoe upper leather" for a time. This leather is mainly used for making boots and bags, with a little thickness, and also a top quality fabric for making skin suits.

The general requirements of "half upper leather" are: thickness 0.gmm - 1.omm (single layer); the softness is the same as that of general garment leather; the compactness is the same as that of ordinary soft upper leather; the grain surface is thin, soft and not loose, and the handle is good.

In order to meet the needs of the market, we have jointly researched and produced sheep half shoe upper leather, and the products have been well received by users.

Some key technical points in the production process are described later for reference by the general leather manufacturers.

1. Selection of raw materials

The production of sheep semi shoe upper leather should be made of high quality soil sheep skin or genuine high-quality North Xinjiang leather, so as to ensure that the finished leather has sufficient tear strength and fine grain surface, and in the process of processing, it does not cause unnecessary trouble, such as reconditioning, rotten lining, etc.

二、溫工段加強脫脂

The key to ensure the quality of sheep semi shoe upper leather is to strengthen degreasing and remove grease from wet sheep.

As we all know, the fat content of sheep skin is large, generally around 30%.

If the degreasing of sheep skin is not enough during leather making, the quality of finished leather will be seriously affected.

For example, the phenomenon of frothing, light extinction, oil penetration, peculiar smell and so on during the storage of finished leather is related to defatting and unclean. Besides, if the oil is not removed, it will also affect the tanning effect, the uniformity of leather dyeing and the fastness of the coating, so we must pay attention to the degreasing situation of sheep skins.

The degreasing of sheep skin should run through the whole wet operation section.

Generally, a series of operations, such as soaking, removing meat, spreading alkali, pushing hair and boiling alkali, can remove the fat on the skin surface (such as fat glands or free fat cells on the surface), but the grease between the nipple layer and the reticular layer is not easy to be removed. Therefore, a multi-stage degreasing process must be carried out to remove it before dyeing and filling.

Different degreasing agents can be used for degreasing before deashing, deashing, softening, pickling, retanning, and even neutralization.

During the leather making process, when the grease is not deactivated, it can also be used to recycle the green leather again and replenish the degreasing to restore the quality.

However, after the painting, the "white frost" and "oil stain" defects appear again. It is very difficult to deal with them and can only be cured.

Three. Before tanning treatment

The general principles for the treatment of sheep semi shoe upper leather before tanning are: to protect the grain surface, to prevent loose noodles, to handle gently, and to avoid being hurried.

To sum up, the main points of each process before tanning are:

1. fast soaking to reduce bacterial production and excessive loss of collagen.

2. before using alkali, pay attention to water control.

3. rolling alkali should not be too strong.

4. ammonium salt deashing.

5. mild enzyme softening.

It is better to use imported enzyme preparation, and at the same time, it should not be too long to soften.

6. it is advisable to control pH at 2.5.

Four. Tannage

The cut of wet blue leather is relatively simple, but it is not easy to do.

In order to ensure the quality of finished leather, so as to avoid the uneven force of the whole skin during ironing and finishing, problems should be strictly controlled, such as uniform thickness of the whole skin, no location difference, no jumping tool, etc.

Five. Retanning

The importance of Retanning is well known.

According to the actual production and product quality requirements, retanning is usually carried out in two stages: the first stage is chrome retanning, and some aliphatic tannins are added to improve the fineness and the fullness of the leather. First, add the chromium powder and add the chrome tannin to improve the firmness and softness of the grain. After adjusting the pH value, stay overnight. The second stage is carried out after neutralization. At the same time, acrylic resin retanning agent, nitrogen containing resin tanning agent, tannin replacement, plant deficiency agent and synthetic tanning agent can be effectively absorbed to achieve better fullness and compactness.

Six. Dyeing and Fatliquoring

Sheep half shoe upper leather is mostly black. It requires that the leather is full and dark. It usually needs two to three times dyeing.

In order to achieve the softness needed for the formation of leather, it is necessary to use high quality fatliquoring agent to grease the semi shoe upper leather of sheep, and the amount of oil should be sufficient. The general amount of mixed and fatliquoring agents should be controlled in 12% to 15%.

Seven, finishing

In order to achieve pleasant appearance and good handle, finishing should also be done. The general process of finishing is:

Spray the water and let it down. One piece of a piece of leather is cut or dried. A crescent cover is pressed. One layer is pressed. One layer is pressed. One layer is pressed and the other is sprayed. The upper layer is sprayed with varnish.

The above introduces some technical keys in the process of producing sheep half shoe upper leather. No specific leather chemicals are listed in the article. We can choose according to our actual situation.

After China's accession to the WTO, the price of most imported leather materials has been accepted by tanneries. Therefore, imported leather chemicals, especially retanning agents, fatliquors and auxiliaries, have been widely used in tanneries. Of course, there are also excellent products such as fatliquoring agents, film-forming resins, etc., because the selection of materials is not difficult, and the key is application and compatibility.

With high quality raw materials and accessories, the quality of sheep semi shoe upper leather can be produced by controlling the degree of attention in production.