Improve The Quality Of Leather In Retanning And Dyeing

I.

Based on the reasons of economy, safety and environmental protection in modern leather making, many tanning workers suggest that they should use the same process as far as possible in the production section with the same style of leather production, but only when they are retanning do they start sorting processing to get different styles of leather.

It can be seen that retanning plays a decisive role in the final characteristics and final quality of leather.

Therefore, the retanning agent has higher requirements. The retanning agent should be permeable moderately and completely accumulate in the sensitive zone between the granular layer and the reticulate layer, so as to enhance the dense, meticulous and fullness of the granules.

Moreover, retanning agents need to entrust leather with solid grain and bone, because in the latter process, leather has to undergo mechanical operations such as pressing, polishing, soften, soften, stretching and so on. Leather is prone to mechanical loosening.

It is impossible to solve many problems mentioned above by simple one or several retanning agents. It is necessary to use a variety of good reagents with good properties to achieve the purpose.

These retanning agents can include acrylic, polyurethane, melamine, protein, aldehydes, naphthalene sulfonic acid synthetic tanning agent, phenol sulfonic acid synthetic tanning agent, tannin extract and so on.

Great changes have taken place in garment leather and furniture leather in recent years. These leather are different from the upper leather, which require the whole leather incision to be dyed. Even high quality shoe upper leather requires 121 of the whole leather cut.

It is more difficult to dye the suede leather surface and incisions with basically the same color, which poses great challenges to dyes, dyeing auxiliaries and dyeing technology.

Therefore, a more high-quality leather retanning agent can be developed in the chemical industry to meet the modern requirements.

Because this kind of synthetic tanning agent has good filling performance, the leather obtained is coarse and plastic.

Fortunately, we have found a new type of polymer tanning agent that can be applied in the leather industry. The tanning agent is different from the synthetic tanning agent in the structure. It is a long chain chain aliphatic or aromatic compound made up of hydroxyl, carboxyl, aldehyde or other functional groups.

Most of the synthetic tanning agents do not have tanning properties. They are made of good combination of leather with chromium salts.

In the application of synthetic tanning agent, the pH value of leather cut should be between 4.5 and 5.

The main tanning agent will make the grain rough, so there will be a lot to do in the design of the process.

Experienced tanning engineers will pre treat the raw leather with synthetic tanning agents or oils before tanning tanning agents.

According to the weight of half finished leather, the amount of material is calculated and the thickness of the finished leather is 1.6mill.

It is important to point out that neutralizing retanning agent Neu.triganP4 can neutralize leather easily and therefore is of great significance.

Similar neutralization and retanning agents have been produced by many foreign companies, but domestic leather companies have little input in this regard, and the market for neutralizing retanning agents is basically occupied by foreign companies.

However, the study of dyeing process is far less than that of dyeing auxiliaries.

The new dyeing auxiliaries form a firm complex with the dye, and then the dye binding speed decreases, the penetration rate increases, and the dyeing time is prolonged. Of course, the leather fatliquoring is promoted during this period.

The stronger the effect, the higher the concentration of dye in the solution. Therefore, the addition of auxiliaries and dyes into the solution can achieve good dyeing results.

The new auxiliaries are not only combined with dyes, but also combine with all anionic products, which are combined with synthetic tanning agents.

In order not to reduce the activity of auxiliaries that bind to dyes, it is recommended that the chrome tanned leather be dyed by the following methods:

The leather dyed by spraying should have good stability to the water, so that the dye will be firmly combined in the leather, so that the dye will not migrate under the action of water.

This method can be used to obtain leather that is completely different from pigment coated and completely maintained aniline leather.

Melamine varnish can be applied to leather to keep the dye's light fastness.

After the EU imposed strict laws and restricted the use of azo dyes with carcinogenic effect, many dyed leather in China could no longer enter the European market.

In addition, the domestic dye has advantages in terms of price, and there is a big gap between its performance and imported dyes. These two aspects are needed by domestic dyestuff companies.