US2523486A - Dehairing of hides - Google Patents

Description

Sept. 26, 1950 R. A. WHITMORE DEHAIRING OF HIDES Filed April 5, 1946 Inventor Faber? A. W/z/fmore By his Attorney Patented Sept. 26, 1950 DEHAIRING or HIDES Robert A. Whitmore, Beverly, Mass, assignor to United Shoe Machinery Corporation, Flemington, N.;J., a corporation of New Jersey Application April 5, 1946, Serial N0. 659,699

5 Claims.

This invention pertains to improvements in methods for dehairing hides and skins by the use of liquid chemical agents.

For the purpose of eliminating verbiage in the present application, the term wet untanned hides" is used and is intended to refer to both hides and skins secured from the fiaying operation without any substantial alteration and also to salted untanned hides or skins which have been wet back to such an extent that the electrolytic content has been reduced and approximates that of fresh hides or skins.

It is one of the objects of the present invention to increase the speed with which the dehairing operation may be carried out. Another object is to provide a method which is not only rapid but which leaves no appreciable harmful efiects as to the quality of the hide and the removed hair.

With these ends in view, the invention contemplates the limited use of a dehairing solution of an electrolytic nature, not as a bath for submerging the hide but merely as an agent for wetting the hair to be removed. An electric current is then passed through the hide, the hair of which is thus treated, and this passage is preferably from the flesh side to the hair side, i. e., the cathode is preferably on the hair side and the anode on the flesh side. As a consequence, the hair is loosened and may be easily scraped or slipped from the hide without appreciable injury to either the hide or the hair.

These and other important features of the invention will be described in detail in the specification and pointed out in the appended claims.

In the drawing, the figure is a diagrammatic and perspective iew of one form of the apparatus suitable for carrying out the method, part of the apparatus being broken away to show the hide being treated.

The apparatus for carrying out the method may be simple in nature and as disclosed includes a plate In of such size as to exceed the size of any work piece to be treated. As shown, a hide l2 to be dehaired is supported for treatment with its flesh-side against the plate 50. The hair I4 of the hide I2 is moistened with an electrolytic solution and a screen [6 is placed thereupon. Two cross-bars l8 and 20 are preferably soldered to the screen [6 and the bar I8 at a medial point is provided with an electrical connection 22 to the line 24 leading to the negative side of a battery or source of current 26. The positive side ofthe source of current is provided with a line 28 connected to the plate ill at plate in pl e of plat It. It is to be understood that the plate In is free of the electrolytic solution as applied to the hair l4. Under such conditions it is clear that the flesh side of the work piece will be free of the applied electrolyte dur-- ing the treatment. In place of the screen IS, a. perforated plate, spaced bars or some other form. of contact means may be utilized although it is; essential that whatever form electrode is used upon the hair side of the work piece, such electrode should be vented to permit gases to emanate.

The preferred material for the electrodes is aluminum as no stains are produced upon the hides when it is used. It should be understood,

3 however, that other materials may be used for the electrodes. This is seen to be so, particularly when it is understood that stains are often unobjectionable for certain uses of the leather ultimately produced from the dehaired hide.

It has been determined that either direct or alternating current may be used although direct current is preferable and has less tendency to heat the hide unduly. Direct current in reverse (using the plate [0 as the cathode instead of as the anode) will serve to unhair hides but not as rapidly as occurs when the hair side is against the negative electrode. The voltage should not be higher than 24 volts if shrinkage of the hides is to be avoided. Amperage will, of course, vary with the size of the work piece and depending uponthe concentration of the electrolyte. It is preferable, however, to use suflicient amperage to avoid prolonged contact of the hair with the electrolytic solution as such contact may soften the hair excessively. j

A number of electrolytic solutions have been used with varying degrees of success and such solutions have varied in concentration from very Weak solutions up to 50% and have been alkaline or approximately neutral, i. e., their pH value has been above approximately 7. Simple experimentation with various solutions and difierent types of skins quickly determines the proper concentration to use. Sodium hydroxide, for example, has been used up to a concentration of 20% at which concentration dehairing has satisfactorily taken place but the hair sufiered damage. The quality of both hair and hide was retained when the concentration of sodium hydroxide was reduced to .5 or 1%. I

' Excessive care need not be used in applying the solution selected to the hair as the hair appears to absorb it by capillary attraction and the hide is quite resistant against penetration by the solution.

The tests have been carried on successfully at difierent temperatures varying from approximately room temperature up to approximately body temperature,

It is preferable to wash the products immediately subsequent to the unhairing step in order that any deleterious action by the unhairing solution be prevented.

It has also been found preferable although not essential to add a diluting agent such as methanol or phenol to the solution. Such addition makes possible a more uniform and satisfactory dehairing operation probably because any tendency for short-circuiting is appreciably overcome.

The following specific examples are merely illustrative of the methods which may be used in carrying out the principles of this invention, the work piece in each instance being a fresh piece of calfskin:

Example 1 Example 2 Dehairing solution: 1% KOH, no alcohol.

Current: Direct, 6 volts, 3 amperes at first for each 3" x unit of skin area reduced to .8 ampere in 3 minutes.

Time of treatment: 7 minutes.

Results: Both hair and skin of satisfactory quality. Hair easily removed.

Example 3 Dehairing solution: 3% LiOl-I, no alcohol.

Current: Direct, 6 volts, 3 amperes reducing to about .8 ampere (for each 3" x 5" unit of skin area).

Time of treatment: 5 minutes.

Results: Both hair and skin of good quality.

Hair easily removed.

Example 4 Dehairing solution: 3% NaCl, no alcohol. Current: Direct, 6 volts, 3 amperes reducing to .5 ampere (for each 3 x 5" unit of skin area).

Time of treatment: 5 minutes.

Results: Products good but hair slightly overheated. Hair did not slip as well as with the use of alkaline substances.

Example 5 Dehairing solution: 5% NaCeI-IaO (sodium phenolate) no alcohol.

Current: Direct, 6 volts, 1.5 amperes down to .5 ampere (for each 3 x 5" unit of skin area).

Time of treatment: minutes.

Results: Products good and hair was removed easily although not so easily as in Examples 1, 2 and 3.

Example 6 Dehairing solution: 5% Na2SzO3.5HzO (sodium thiosulfate) Current: Direct, 24 volts, 3 amperes (for each 3 x 5" unit of skin area).

Time of treatment: About 3 minutes.

Results: Ease of unhairing and quality of products both satisfactory.

Example 7 V I .Dehairing solution: 2.4% NaOH and 2% C'sHsO (phenol).

Current: Direct, 6 volts, 1.5 amperes at first reducing to 1 ampere (3" x 5").

Results: Unhairing easily done and products of good quality although skins were horsed up for 30 minutes without Washing.

Having described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of dehairing a wet untanned hide having an electrolytic content approximately that of a fresh hide which comprises the application of an electrolytic solution having a pH value above approximately seven to the hair side only of such a hide, spreading out and pressing the hide between two electrodes, and passing an electric current through the thickness dimension of the hide while one of said electrodes is free of said electrolytic solution.

2. The method of dehairing a wet untanned hide having an electrolytic content approximately that of a fresh hide which comprises application of a dilute electrolytic alkaline solution to the hair side only of such a hide, spreading out and pressing the hide between two aluminum electrodes, and passing a direct current through the thickness dimension of the hide from one aluminum electrode to the other while said other electrode is free of said applied solution.

3. The method of dehairing untanned wet hides each having an electrolytic content not in excess of that in a fresh hide which comprises the application of an alkaline electrolytic solution to the hair side only of such a hide, spreading out and pressing the hide between two electrodes, passing an electric current through the hide for sufficient time to loosen the hair while one of said electrodes is free of said solution, and subsequently removing the loosened hair from the hide.

4. The method of dehairing \vet untanned hides each having an electrolytic content approximately that of a fresh hide which comprises the application of an electrolytic solution having a pH value above approximately seven to the hair side only of such a hide, and passing a direct current through the hide from the flesh side to loosen the hair while the flesh side is free of the applied solution.

5. The method of dehairing wet untanned hides each having an electrolytic content approximately that of a fresh hide which comprises the spreading out of such a hide, aplying an electrolytic solution having a pH value above approximately seven to the hair side only, passing an electric current through the hide from the flesh side to the-hair side while the fiesh'side is free of said applied solution, the said current being of suflicient intensity to loosen the hair, and subsequently removing the loosened hair from the hide.

ROBERT A. 'WHITMORE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 653,716 Van Gestel July 1'7, 1900 683,836 Berget Oct. 1, 1901 737,882 Strecker Sept. 1, '1903 976,036 Burton Nov. 15, 1910 FOREIGN PATENTS Number Country Date 4,488 Great Britain 1- Sept. 16, 1909 Certificate of Correction Patent No. 2,523,486 September 26, 1950 ROBERT A. WHITMORE It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 4, between lines 2 and 3, insert Time of treatment: 10 minutes;

and that the said LettersPatent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 3rd day of April, A. D. 1951.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

Claims (1)

1. THE METHOD OF DEHAIRING A WET UNTANNED HIDE HAVING AN ELECTROLYTIC CONTENT APPROXIMATELY THAT OF A FRESH HIDE WHICH COMPRISES THE APPLICATION OF AN ELECTROLYTIC SOLUTION HAVING A PH VALUE ABOVE APPROXIMATELY SEVEN TO THE HAIR SIDE ONLY OF SUCH A HIDE, SPREADING OUT AND PRESSING THE HIDE BETWEEN TWO ELECTRODES, AND PASSING AN ELEC-

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