US2312998A - Process for hardening fibrous protein material - Google Patents

Description

Patented Mar. 2, 1943 PROCESS FOR HARDENING FIBROUS PROTEIN MATERIAL George Stephan de Kadt, Leeuwarden, Netherlands; vested in the Alien Property Custodian No Drawing. Application February 17, 1939, Se-

rial No. 257,028. In the Netherlands March 1,

8 Claims.

My invention relates to a process for hardening fibrous protein material, such as fibres, filaments, threads, films and the like.

It is generally known in order to render products from proteins, for example casein, unsoluble, to harden these products in baths, containing as hardening reagent methanal. The hardening is then effected by introducing products into a methanal containing bath in which they are kept for a long time, depending on the conditions, to obtain a sufiicient hardening. It is also known to make use of various baths of increasing concentrations of methanal or of baths in which besides methanal salts or acids are dissolved.

This process takes up much time and therefore requires much place for being operated. Moreover this process cannot be relied upon. In fact the drawback is encountered that repeatedly fibres treated in this way are only suficiently hardened in appearance but not in reality, which among others maybe demonstrated by boiling these fibres in water. By this simple operation the fibres are commonly attacked in such manner that they even may lose the fibre structure. It is evident that faultless boilingproofness is a requirement of primary importance in the manufacture of synthetic fibrous materials. After elaborate experiments I succeeded in finding a process which not only results with absolute reliability in a boiling proof product, but'which is moreover very economical from a view point of time and operation space.

According to my invention the fibrous protein materials are treated with a methanal containing medium of elevated temperature, 1. e. at least above 70 C. for a short time. Excellent results are obtained by boiling the fibres, threads and the like for some time in an aqueous bath containing methanal. It is preferred to introduce the product gradually into the bath at this high temperature. Other substances may be added to the methanal bath such as for instance sodium chloride, magnesium sulfate, glycerol, glucose, etc. Particularly such substances may be added which form artificial resinous products with methanal and the incorporation of which into the protein fibres may be of importance for the properties of these fibres. Examples of such substances are urea, thiourea, phenol, and the like. When adding such substances as a rule a higher methanal concentration is necessary.

According to the invention it appears that the addition of alkali or alkaline salts in such quantity that the methanal bath gives a weak alkaline (Cl. 1H8) reaction has a favorable influence on the hardening process and on the quality of the fibres. This is surprising, because it could not be expected from an alkaline bath.

With regard to the volatility of methanal and of volatile bases if present, the treatment may be effected in closed vessels andhereby application of temperatures above the normal boiling point is possible.

It must be emphasized that the effect of the invented process is not simply the result of an acceleration of the reaction by increasing the temperature. It appears that even by treatment at lower temperature continued for a very long period the same result cannot be obtained as effected by boiling for a short time.

Moreover the agitation caused by the vapour bubbles developed during boiling seems to be of importance. According to my invention this agitation may also be obtained by agitating the bath in other way, preferably by blowing in vapours or gases, such as for instance methanal containing steam.

Though in general treatment in a methanal containing bath of higher temperature is preferred it is also possible to harden in a methanal containing atmosphere of high temperature and if desired this atmosphere may have a weak alkaline reaction by admixture of volatile bases, such as for instance ammonia. For instance the protein materials may be treated in a weakly ammoniacal atmosphere of steam and methanal at approximately 100 C. By a methanal containing medium (bath or atmosphere) I also mean a bath or atmosphere of substances yielding or splitting of methanal, such as paraldehyde, hexamethylenetetramine and the like. An example of a very suitable combination according to my invention is the following;

Casein fibres freed of acid by washing are led into a bath containing 4% of methanal, 5% of sodium sulfate, 2% of sodium acetate in a proportion of 100 kg. of fibrous material to 1700 kg. of bath liquid. The temperature is raised to C. in 45 minutes. The fibrous mass is then maintained in the boiling bath for 15 minutes.

Obviously my invention is not at all restricted to this example. Often it may be advantageous to subject the fibrous materials to a prehardening for instance in a methanal bath which per se 1 does not result in a sufiiciently resistant product.

The process of my invention is not only applicable to the casein mentioned but also to any protein of animal or vegetable origin suitable or rendered suitable for being spun and also to mixtures of one or more proteins with viscose;

What I claim is:

1. Ina process for the treatment of fibrous pro- I tein material, which is hardenable by the action 01' methanal, the step which consists in hardening the said material by contacting the same with a methanal-containing medium by immersing the material in a methanal-containingbath at a boiling temperature above 70 C. for a maximum or about one hour, and agitating the bath during such immersion.

2. Ina process for the treatment of fibrous protein material, which is hardenable by the action of methanal, the step which consists in hardening the said material by contacting the a same with a methanal-containing medium by immersing the material in a methanal-containing bath at a temperature above 70 C. for a maximum of about one hour, and agitating the bath by blowing gas thereinto during such immersion.

3. .A process for hardening fibrous protein material which consists in contacting the said material with a methanal-containing medium by immersing the material in a methanal-cont'aining bath at a temperature above 70 C. tor a maximum oi. aboutone hour, and agitating the bath by blowing methanal-containing steam thereinto during such immersion. I

4. A process for hardening fibrous protein material which consists in contacting the said mamethanal and at least one alkaline salt at a temperature above 70 C. tor a maximum or about one hour.

5. In a' process for the treatment of fibrous protein material, which is hardenable by the action of *methanal; the step which consists in hardening the said material by contacting the same with a methanal-containing medium by immersing the material in, a bath containing methanal and at least one substance which is capable of forming asynthetic resin with methanal,

at a temperature above 70 C. for a' maximum 01' about'one hour.

6. A process for harden-lng fibrous protein material which consists in contacting the said ma- ."terial with a-methanal-containing medium having a weak alkaline reaction, at a temperature ening the said material by boiling the same in a terial with a methanal-containing medium by immersing the material in a bath containing methanal-co'ntaining medium for a maximum of about one hour.

GEORGE STEPHAN 1m K'ADT.