BE403029A - Process for improving the flexibility of leather - Google Patents

Description

       

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 EMI1.1
 oced for improving the suppleness of the leather. -0
It is known that animal skins must be subjected before tanning to a preparatory treatment for the separation of the epidermis and the underlying layer.



  After calcination and after removal of the top pile layer, the leather hide is generally in a highly swollen, full and "firm" state and has milk of lime residue inside. If the skin is tanned in this swelling state, it results in bad leather. By using maceration baths, such as bran baths, excrement baths etc. or also pure enz, ymes, the swelling of the skin is reduced, that is to say that the skin is brought to a softened and flabby state, so that the residual impurities, even those retained inside it can be mechanically removed without difficulty. At the same time, the surface of the skin acquires

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 the favorable condition necessary for tanning, which is recognized by the slippery erasure which it takes.

   The flexibility of the resulting leather after tanning is, apart from the specific action of the calcining agent, greatly dependent on the degree of subsequent removal of the calcining agent and impurities.



   Now, it has been found that the washing and emulsifying agents prepared according to French patent No. 620.120 by means of pyrophosphates and gum, gelatin, albumins, saponin, casein, etc. also render excellent services for the preparatory treatment of hides before tanning for the production of extremely flexible leathers. If the animal skin prepared as usual for tanning is treated with a bath containing a preparation established according to the said French patent, this treatment being able to precede or follow the maceration operation, after tanning is carried out , leathers which are much softer than those obtained by the usual maceration processes. It is even possible to replace the usual maceration process by the particular treatment indicated according to the invention.

   The duration of this advanced treatment depends on the desired effect; the same is true of the concentration of the baths.



   E x e m p l e.



   The skins prepared in the ordinary way by calcination and maceration are put on the oars or introduced into the drum together with the quantity of water required at a temperature of 35 to 40 C. and stirred or stirred in this bath for 1 to 3 / 2 hours adding 1 to 3/2 percent of a mixture of

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 2 parts of neutralized sodium pyrophosphate and 1 part of casein, then they are rinsed and subjected as usual to the tanning operation. The quantity added of the mixture of pyrophosphate and casein depends on the nature of the skins; the more fat they contain, the greater the amount of mixture to use.



   Summary.

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Claims (1)

The invention comprises: 1). A process for improving the flexibility of leathers, consisting in treating the skins, during their preparation for tanning, with a solution of the washing and emulsifying agents prepared according to the said French patent by means of pyrophosphates and gum , gelatin, albumins, saponin, casein etc .; 2). The new application of these agents in the processes of tanning hides; 3). Skins and leathers obtained according to the new process and exhibiting remarkable flexibility. ** CAUTION ** end of field CLMS may contain start of DESC **.