US2318454A - Washing and deliming composition for limed hides - Google Patents

Description

Patented May 4, 1943 WASHING AND nELiMiNG COMPOSITION ron LIMED HIDES I No Drawing. Application July 13, 1940,

- Serial No. 345,414

4 Claims.

This invention relates to washing and deliming compositions for limed hides, furs and the like.

It is known that the pH value of the adhering liquids of hides, the amount of swelling, and the amount of hydrolysis of the collagen materially afiect treatment operations involving hides and hairs and to a great extent the quality of the resulting leather.

It is almost a universal practice to remove hairs from various skins by soaking them in a lime bath until the hairs are sufliciently loosened to be easily removed either by hand or by unhairing' machinery. When the hides have reached a state where the hairs are sufliciently loosened, they are removed and unhaired. Then it is necessary to delime the hides so as to bring them into a proper state of alkalinity and to prevent undue swelling and disintegration of the leather-forming portions of the hides. Numerous agents have been suggested for use in deliming baths but most of these agents have proven unsatisfactory due to the fact that they cause excessive swelling of the hides, are ineflicient in use or result in an insuflicient removal of lime.

It is an object of thepresent invention to provide improved deliming and alkalinity controlling compositions for use in deliming baths.

7 The compositions of the present invention contain primarily first run fatty acids of 4. to 6 carbon atoms derived from distilling the oxidation products of parafiin hydrocarbons in combination with a. small percentage of the ammonium salt of sulfonated oleyl alcohol, and an even smaller percentage of triethanol amine. constituent may be designated as mid-fraction fatty acids and contain more than 3 carbon atoms and less than 8 carbon atoms in the fatty acid radicals. Other water-soluble salts of the imsaturated higher molecular fatty alcohol sulfonates may be used in the compositions of the invention with somewhat less satisfactory results.

The fatty acid acids. Agitation is continued until a stable homogeneous mass is provided. This product is provided for the trade in an anhydrous condition and is very active when mixed with aqueous washing baths for deliming.

The compositions of the present invention do not contain any mineral acids or salts to react with the hides to produce swelling. Hence they produce a very mild effect upon the hides being treated and do not result in a deleterious swelling. On the other hand, these mildly active organic compounds form readily soluble-lime salts with the lime present in the unhaired hides. These salts are not adsorbed or absorbed in the struc-. ture of the hide and are easily washed out in the deliming bath or in subsequent rinsing baths.

It has been found that much smaller percentages of the compositions of the present invention are efiective for addition to the treatment baths in the deliming operations than has been necessary with prior deliming compositions. In fact, percentages which are one-third of those heretofore used with known deliming and washing agents have proven to be effective. Naturally the amount of deliming agent will depend somewhat upon the amount of lime present in the hide structure, the type of hide being treated and the kind of leather to be produced. However, de-

, liming baths incorporating less than 1% of the A typical composition of the nature of the ones The fatty acids used in the above example have an acid number of 516, a saponification number of 530, an iodine number of 7, a hydrogen number of 0 and an average molecular weight of 106.

The compositions are usually prepared by introducing the sulfonated alcohol and the triethanol amine into a vessel provided with an agitator which contains the lower molecular fatty deliming compositions of the present invention have proven to be amply satisfactory. In fact, less than .5% of these compositions are usually suflicient. In accordance with the preferred practice the deliming bath is gradually brought to the proper strength by small additions of the deliming agent. This is especially true -when treating sensitive hides. The deliming baths usually contain from 200% to 600% water based on the weight of the unhaired hides. The preferred temperature of the bath ranges from 28 to C. a

The following examples serve to indicate typical deliming treatment baths for the production of special leathers from various types of hides.

Percentage of deliming Kind of Type of Length of composition hide leather treatment CBIL B 1 (s rifle ox do .t. 1 do 'Chevnettes" K Do. do.. Case Do.

The compositions of the present invention are so effective in their deliming function that substantially all the lime can be removed from the hides. Bating agents, therefore, frequently are unnecessary. If the use or hating agents is felt 2,318,454 UNITED STATES PATENT "OFFICE desirable, they can be a ded to the deliming baths'per set without the necessity of providing separate baths. Hides treated with the deliming agents of the present invention are clear and clean and have a delicate grain. The resulting leathers have good fullness, a close solid grain,

sulfonated higher molecular unsaturated pri-' mary alcohol and triethanol amine.

2. A deliming composition consisting essentially of 95 parts or fatty acids of 4 to 6 carbon atoms, 4 parts of the ammonium salt of commercial oleyl alcohol sulfonate and 1 part of triethanol amine.

3. An aqueous treating bath for deliming hides containing less than .5% of a deliming agent containing a mid-fraction fatty acid of 4 to 6 carbon atoms, an ammonium salt of sulionated oleyl alcohol and triethanol amine.

4. A process for deliming hides which comprises subjecting a hide to the deliming action of an aqueous treating bath containing as a deliming and cleaning agent a composition consisting of a fatty acid of 4 to 6 carbon atoms, the ammonium salt of suifonated oleyl alcohol and triethanol. amine, said treatment taking place at a temperature of 28 to 35 C.

' HEINRICH BERTSCH.

FRIEDRICH SCHMI'I'I.