US1827163A - Lustering leather - Google Patents

Description

Patented Oct. 13, 1931 UNITED STATES PATENT OFFICE GEORGE E. PENSEL AND SVEN H. FBIESTEDT, OF AMSTERDAM, NEW YORK, ASSIGNOBS T BITTER CHEMICAL COMPANY, OF AMSTERDAM, NEW YORK, A CORPORATION OF NEW YORK 1T0 Drawing.

' This invention relates to the manufacture of lustrous dyed or undyed leather having a nap, and especially to the treatment of formaldehyde or chrome tanned leather having 5 a nap, such for example as suede or mocha leather.

It is well known that if woolis treated with available chlorine it acquires a luster and feel very similar to silk, and it loses its felting properties, but it also ac uires a greater affinity for dyestuffs (see anual of Dyeing by Knecht, Rawson and Loewenthal, Griffin & Company, London, second edition, 1910, pages 56, 57 and 58).

We discovered that the raw skin might be treated with available chlorine, for example, before the chrome tannage, after it has passed through the usual beam shop process, for the removal of the hair, such as liming, puering or drenching. For example,'untanned skins,

say one or two such skins, are placed in a drum and enough sodium hypochlorite solu tion of 33 B. is added to conveniently cover the skins, whereupon the drum is rotated for if about forty-five minutes at room temperature.

With the ordinary drum about twenty pounds of the sodium hypochlorite solution will be used. The liquid is then drained off and 140 grams of sodium hydroxide dissolved in twenty 3 pounds of water are added, whereupon the drum is run for fifteen minutes more. The liquid is then drained and 450' grams of 80%' acetic acid dissolved in twenty pounds of Water are added, and the drum run until I 35 all the caustic soda present is completely neutralized, as determined by a test with phenolphthalein. The liquid is then again drained and the skins pickled and tanned in the usual manner. Such skins after being finished 4 show considerable luster but do not compare in sheen with skins lustered after the tanning process. There is also a serious objection to Application filed January 18, 1930. Serial No. 421,808.

. LUSTERI'NG LEATHER ed, and consequently it is desirable to luster after the tanning process has been completed.

Sodium hypochlorite may be used for lustering leather when used alone or with other reagents, but it does not result in the very desirable product obtained by the use of my preferred process hereinafter described. l/Vhen leather is treated with sodium hypochlorite solution containing monosodium phosphate in such an amount tha the solution is no longer alkaline to pheno phthalein indicator, for example, with a solution containing 20% of sodium hypochlorite having 6.5% available chlorine, and 10% of monosodium phosphate, for thirty minutes, and then dyed and dried out, or when leather is treated with a similar solution but containing 10% of ammonium chloride in place of the mono-sodium phosphate, and then dyed and dried out in the usual manner, a fairly good product results, but it is not of the same quality as when treated according to'the preferred process.

We have discovered that almost any chlorinating agent will cause some lustering of formaldehyde or chrome tanned leather having 'a nap, such as suede or mocha leather, al-

though som chlorinating agents have in addition to the lustering effect a more or less undesirable effect of one kind or another, and we therefore prefer not to use them.

We also discovered that said luster may be produced by treating chrome tanned leather with various stripping or detanning agents, such as ammonia, sodium diphosphate, sodium triphosphate, sodium tartrate,sodium citrate and the like, but the resulting luster is not sufficient for commercial success.

We have also discovered that available chlorine from substantially neutral reagents will give a good lustering effect on leather similarly to the lusterin efiect on wool as described above, and suc results are especially good with chrome tanned and formaldehyde tanned leathers having a'nap such as suede or mocha leather. Various substances may be used as the sourcefor obta ning the chlorine but of all those wehave tr ed we prefer to use the various organic chlorine compounds such as are described by Chattaway in the Chemical Society Journal (London), 1905, vol. 87, pages 145-171, and of these we prefer the sodium salt of paratoluenesulphochloramide, also known as Aktivin, since this works eficiently in theprocess and is easily obtainable in commerce. We will here describe the use of 'Aktivin only, of such compounds, for lustering leather since the process is essentially the same for all such compounds except the amounts to be used, which can be calculated.

Aktivin is ordinarily neutraland evolves chlorine in contact with other organic compounds which are oxidizable, such as wool, cotton and the like. We obtain some luster by using the Aktivin in amounts from to 5% of the dry weight of the leather, andthe luster is improved by the presence of an acid, such for example as formic acid, acetic acid, oxalic acid, hydrochloric acid, sulphuric acid and the like.

We have also discovered that a superior luster is obtained by combining the step of treating the leather with a detanning agent with the step of treating it with the chlorinating agent, for example:

l. A tanned shn is treated with a solution containing ammonia in an amount equal to about 5% of the dry weight of the leather,

and ivin in an amount equal to about of the dry weight of the leather, for about a half hour, whereupon it is washed and dyed in the usual manner.

2. .The process is the same as noted above under No. 11, except that the solution contains l0% of trisodium phosphate instead of the Men in an amount equal to about 10% of the dry weight of the leather.

3. The skin may be first treated without the Aktivin, that is, with the ammonia solution or trisodium phosphate solution or both of these together. After such treatment for one-halfhour the skin is washed, and then treated in a second bath with a solution containing 10 to of Aktivin and 5% of formic or other organic acid, or 2 to 3% of mineral acid, the percentages stated being likewise based on the dry weight of the leather.

Each of these three very beautiful luster.

We have also discovered that an excellent luster is obtained by using a mixture of Aktivin d a tanning material in place of the Alrtivin alone; and we prefer to use the synthetic tans-which as a rule are phenol sul phonic acids condensed with aldehydes, very good results being obtained as ageneral rule with the addition of about two parts of the added tanning material to t parts of the methods produces a memes Aktivin used. Our preferred method of procedure is to wet back the dry chrome or formaldehyde tanned suede or mocha leather with a wetting out agent, such as a solution of ammonia, sulphonated castor'oil, carbon tetrachloride, trichlorethylene, Nekal, the wetting out agent described in the patent to lPott No. 1,686,836, Uctober 9, 1928, or any other suitable wetting out agent, together with a detanning agent such as disodium phosphate, trisodium phosphate, sodium citrate, sodium tartrate, or ammonia for about twenty to thirty minutes at a temperature of about 110 to 120 16. As a specific example we may state that pounds of dry leather are placed in an ordinary wooden drum with enough water to cover the skins at a temperature of 120 F, three pounds of trisodium phosphate and three pounds of a mixture of about equal parts of saponified sulphonated castor oil and trichlorethylene being added'thereto, and the drum is then rotated for about thirty minutes, whereupon the skins are washed at to F. for about twenty to thirty minutes to remove the wetting out agents. At this stage, the leather is in a soft slimy condition. The skins are then treated with an aqueous solution of Aktivin containing 10 to 15% of Aktivin based on the weight of the dry skins,

enough water being used to cover the skins, and'the solution may not, but preferably does, contain acid as above described, this treat ment being preferably at a temperature of 100 to 18. After treating thus for about ten minutes 4%, that is, four pounds per one hundred pounds of dry skins, of tanning material is added to the solution, and this treatment is continued for about fortyfive minutes to one hour, preferably at a temperature of 100 to 140 F. The leather is then washed thoroughly preferably with warm water and dyed in any well known manner. ,After dyeing it has the desired luster as well as the desired color, the color being fast to light and washing. It is to be noted that better and quicker results are obtained the higher the temperature of treatment, but it is advisable not to let the temperature ever exceed 140 F, as this may cause the leather to deteriorate.

Elemental chlorine v and bromine, when used in place of the Aktivin, likewise produce a lustrous effect on the leather.

The lustering treatment not only produces a luster, but it also makes the leather more receptive to most dyes.

When it is desired to dye the treated leather, this is best done without again drying it, that is, after the last washing step described above.

' To one hundred pounds dry weight of wet leather in a drum we add about five pounds lllti of disodium phosphate, or three pounds of Y trisodium phosphate, or two pounds of disodium phosphate together with two pounds 1 of borax. These substances act to retard the,

aflinity of the dyestuif for the'leather whereby better penetration of, the dye into the drum, the addition of the formic acid re quiring about fifteen to twenty minutes, the formic acid acting to overcome the retarding efiect of the sodium phosphate, borax, and the like on the aflinity of the d e for the leather. After all the formic aci has been added, rotation of the drum is continued for another twenty minutes, whereupon the leather is washed very thoroughly and dried.

Having thus described the invention, what is claimed as new and desired to be securedby Letters Patent is: i

1. The process of lustering formaldehyde orchrome tanned suede or mocha leather, which comprises subjecting it to the action of a chlorinating agent.

2. The process of lustering formaldehyde or chrome tannedsuede or mocha leather, which comprises subjecting it to the action of an organic compound containing available chlorine.

3. The process of lustering formaldehyde or chrome tanned suede or mocha leather, which comprises subjecting it to the action of Aktivin.

4. The process of lustering formaldehyde or chrome tanned suede or mocha leather, which comprises treating it'with a wetting out agent containinga mild detanning agent to soften it and to detandt slightly, washing it, treating it with water containing a chlorinating agent, adding tanning material to said water to neutralize the partial detanning, and then washing.

5. The process of lustering formaldehyde or chrome tanned suede or mocha leather, which comprises treating it with a wetting out agent containing a mild detanning agent to soften it and to detan it slightly, washing it, treating it with water containing an or-. ganic compound containing available chlorine, adding tanning'material to said water to neutralize the partial detanning, and washing. 7 V

6. The process of lustering formaldehyde or chrome tanned suede or mocha leather, which comprises treatingv it with a wetting out agent containing a mild detanning agent to soften it and to detan it slightly, washing it, treating it'with water containing Aktivin,

adding tanning material to 'said'wateito neutralize the partial detanning, and washing.

1 7. The process of lustering formaldehyde or chrome tanned suede'or mocha leather,

which comprises treating it with a wetting out agent containing a mild detanning agent for about one-half hour at a temperature ofabout 110 to 120 F., to soften it and to detan it slightly, washing out said treatlng agents, treating it with water containing ns about '10 to 15% of Aktivin based on the weight of the dry leather for about ten mmutes, adding to the treating agent 4%, based on the weight of the dry leather, of'synthetic tanning material containing a sulphonic acid radical, treating the leather therewith for about forty-five minutes, and washing out the reagents. v I

8. .The process of lustering formaldehyde or chrome tanned suede or mocha leather, which comprises treating it with a wetting out agent containing a milddetanning agent for about one half hour at a temperature of about 110 to'120 F., to soften it and to detan it slightly, washing out said treatingagents, treating it with water containing about 10 to 15% of Aktivin based on the weight of the dry leather for about ten minutes, adding to the treating agent 4%, based on the weight of the dry leather, of synthetic tanning material containing a sulphonic acid radical, treating the leather therewith for about forty-five minutes, washing out the reagents, and dyeing the leather.

9. The process of treating chrome tanned or formaldehyde tanned leather having a nap, which comprises treating it with a chlorinating agent, washing, and dyeing it. 10. The process of treating chrome tanned or formaldehyde tanned leather having a nap, which comprises treating it with a wetting out agent and a detanning agent, washing it, treating it with alustering agent, adding a tanning agent to the lustering agent and continuing the treatment, and washing it.

11. The process of treating chrome tanned or formaldehyde tanned leather having a nap, which comprises treating it with awetting out agent and a detanning. agent, washing it, treating it with a chlorinating agent comprising acid, adding a tanning agent to the lustering agent and continuing the treatment, and washing it. ,4

12. The process of treating chrome tanned or formaldehyde tanned leather having a nap, which comprises treating it withia wetting out agent and a detanning agent, washing it, treating it with a lustering agent, adding a tanning agent to the chlorinating agent and continuing the treatment, washlng it, and. dyeing it,

. 13. The process of treating chrome tanned or formaldehyde tanned leather having a nap, which comprises treating it with a wetting out agent and a detanning agent, washing it,

. hwittlt treating itwith n ohloninaating agent com-- prising new, adding a tanning agent to the lustering agent and continuing the treatment 7 Washing it, nnol dyeing it.

v M. A lnstei'edl leather produced by pertielly oletanning the leather subjecting it to the action of & ohlorineting agent and Iceting it.

15. A lustrous leather protuced by sub- 10 jeoting chrome or formaldehyde tnnnedl leather to the notion of Aktivin.

In testimony whereof we hereunto afix our signatures,

GEQRGE R. PENSEL.

i5 SVEN H. lFRllESTED'l.