JPH0533000A - Production of organic composition for chrome tanning - Google Patents

Abstract

PURPOSE:To obtain an organic composition capable of enhancing effects on adsorption and reaction of a chrome tanning agent on hides by treating cattle hair with an alkali, partially hydrolyzing hard proteinaceous keratin which is a main constituent ingredient and regulating the pH of the resultant substance. CONSTITUTION:Cattle hair produced in an unhairing step of cattle hides is treated with an alkali using calcium hydroxide, etc., and hard proteinaceous keratin which is a main constituent ingredient of the aforementioned cattle hair is then subjected to partial protein hydrolysis by alkaline hydrolysis, acid hydrolysis, enzymic hydrolysis, etc., to prepare a water-soluble keratin protein having the average molecular weight within the range of about 1000 to 36000. An organic acid such as formic acid or succinic acid or its salts are subsequently added to the resultant water-soluble protein to regulate pH between 3.0 and 4.5. Thereby, the objective composition is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an organic composition for treating leather in the production of chrome tanned leather before adding a chrome tanning agent. More specifically,
The present invention relates to a method for producing an organic composition which is useful for treating a chrome tanning agent, using as a raw material body hair, which is a by-product, in the hair removal process of cowhide.

[0002]

2. Description of the Related Art In the hair removal process of cowhide, which has been widely used in the past, first, a reducing agent, an enzyme, etc. are added to the hair to break the disulfide bond of the hair, and then calcium hydroxide is added to completely dissolve the cowhide. Then, it is placed in a waste liquid treatment tank together with the lime pickling waste liquid and treated by a precipitation method or an activated sludge method.
At this time, the BOD of the lime pickling waste liquid is 20,000 to 24,000 pp.
m.

In the solubilization of the keratin protein used in the leather tanning process, a conventional disulfide bond is cleaved and then a peptide bond in the main chain is cleaved by treatment with an enzyme or the like to prepare a water-soluble keratin solution. However, this treatment decomposes keratin to the amino acid stage. Therefore, when this keratin hydrolyzate is used for the adsorption reaction of the chrome tanning agent on the skin, the chrome tanning agent is first adsorbed on the decomposed amino acid, and the tanning agent penetrates into the skin and collagen fibers May block the reaction of.
Also, it takes several days to prepare the keratin hydrolyzate,
Moreover, the extracted keratin hydrolyzate (pH about 6.0-7.0)
Since chrome tanning agents are added to the leather first, the keratin hydrolyzate is added in place of the conventional basicity increasing agents, since precipitation tends to occur at pH 4.5 and below.

Furthermore, the pH of the keratin hydrolyzate itself
Therefore, the keratin hydrolyzate is mainly used for the adsorption reaction of the chromium tanning agent used in the retanning process.

However, in any of the above cases, no efforts have been made to improve the problem of treating industrial waste liquid having a high BOD and containing heavy metals.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to the effective use of body hair, which is a pollution waste, which is generated in the hair removal process of cowhide, which has been conventionally used in the field of leather production, and the BOD contained in factory waste liquor. The current 20,000 to 24,000 to 1
The purpose is to reduce the number to 0,000.

Further, by improving the adsorption reaction of the chrome tanning agent on the skin, the amount of the chrome tanning agent used is reduced, and at the same time, the concentration of the chrome waste liquid discharged from the tanned leather is significantly reduced as compared with the conventional one.
The purpose is to contribute to the reduction of chromium tanning agents used in the tanning factory and improvement of wastewater treatment process.

[0008]

According to the present invention, BOD of lime waste liquid discharged from a factory is recovered because cow hair, which has been mixed and discarded in a factory waste liquid in the past, is separated from the skin surface and is not dissolved in a liquid medium. Decrease. Collect this cow hair in a short time,
The recovered hair is partially decomposed into proteins to obtain water-soluble keratin,
It is intended to provide a method for producing an organic composition in which an organic acid or a salt thereof is added to improve the adsorption reaction of a chrome tanning agent on the leather in the leather tanning step.

[0009] A main aspect of the present invention lies in that the target organic composition is produced by collecting and preparing cow hair as it is. That is, hair roots are relaxed with calcium hydroxide in the hair removal process of cow hair, and then a reducing agent (sodium hydrosulfide, sodium sulfide, mercaptans, amines, etc.) is added to remove hair. To take this cow hair out of the reaction system, a drum equipped with a liquid circulation device and a pipe is used. Liquid circulation device A rotary centrifugal separation type filtration device (cement mixer type) was installed in the middle of the pipe to push cow hair out of the system and at the same time,
The alkaline treatment liquid is returned to the drum again through the circulation pipe.

Another aspect of the present invention is that a composition having a uniform molecular weight can be prepared by controlling the molecular weight of the target composition. That is, the cattle hair taken out of the system was partially converted from the disulfide bond (S-S) in the keratin molecule into a thioether bond (-S-) by the alkali treatment with calcium hydroxide. A feature of the present invention is that, unlike the conventional method of cleaving a disulfide bond to form a thiol group (SH-), a cysteine residue having a disulfide bond is changed to a lanthionine residue having a thioether bond ( (See JP-A-2-51533). The thioether bond produced by this reaction is so strong that it remains in the keratin protein without being cleaved in the partial decomposition step of the protein after the alkali treatment. Therefore, it is possible to control the molecular weight of the final product, the water-soluble keratin protein, by controlling the production of lanthionine residues during the alkaline treatment (see Japanese Patent Laid-Open No. 2-51533).

The control of the production of lanthionine residue can be changed depending on the conditions such as the concentration of the alkaline salt solution, the alkaline treatment time and the temperature. In a preferred embodiment, when the cowhide is treated in a calcium hydroxide saturated solution at a temperature of 20 ° C to 30 ° C and a pH of 11 to 13 in the alkaline treatment hair removal step of the cow's hair, if the alkali treatment time is long, It is well known that the degree of conversion of the cysteine residue to the lanthionine residue is increased, an immune action occurs, and the hair removal treatment is not completely performed. If the alkaline treatment conditions are determined in advance and combined with the conditions for the subsequent partial decomposition of the protein, the molecular weight of the final water-soluble keratin protein can be adjusted more accurately.

As used herein, the term "immunity" refers to the use of calcium hydroxide alone in the hair removal process to cleave the disulfide bond (S-S) of keratin to give a thiol group (-SH). , Its thiol group binds to various reactive groups in keratin to cause a secondary bond between the polypeptide chains, and again produces an amino acid group of a thioether bond, for example, a lanthionine bond, so that the hair removal effect is rather returned. This is a phenomenon that is prevented (see Makoto Kamiya, Shufu no Tomo Shuppan Service Center Edition, Leather Processing Science, page 64). As the alkaline treatment conditions, when calcium hydroxide is used as the alkaline salt, the concentration is 0.1% by weight.
It is preferable that the saturated solution (3 to 4% by weight), pH 11 to 13, temperature of 40 ° C. or less, and immersion treatment time be within 24 hours. In the case of sodium hydroxide or potassium hydroxide, the concentration is 0.001
It can be used under the same conditions as calcium hydroxide at ~ 0.1N.

It is also well known that the above alkali treatment does not substantially change amino acid residues other than cysteine residue and lanthionine residue (Japanese Patent Laid-Open No. 2-5153).
No. 3 bulletin).

Actually, the cow hair taken out of the system after alkaline treatment of cow hair is subjected to partial protein decomposition.
For this partial decomposition, ordinary methods such as alkali hydrolysis, acid hydrolysis, enzymatic decomposition, oxidative decomposition or reductive decomposition can be used as they are. In the conventional method, hydrolysis proceeds to the amino acid level in this partial decomposition, but in the present invention, due to the presence of the above-mentioned lanthionine group, the decomposition proceeds only to a polypeptide having a molecular weight of 1,000 to 36,000 (JP-A-2-51).
No. 533). In the partial decomposition of proteins by alkaline hydrolysis, 0.1-10% sodium hydroxide aqueous solution 4-
Add 1 to 2 Kg of hair to 8 Kg, 70 to 100 ℃,
Degradation is performed for 1 to 24 hours to obtain a water-soluble keratin protein. Conditions for partial degradation of other proteins can be experimentally determined by those skilled in the art. After the partial decomposition is completed, the solution is filtered and decolorized, and the solution is added with an organic acid or its salts (formic acid, oxalic acid, lactic acid, succinic acid,
Citric acid, malonic acid, maleic acid, phthalic acid, adipic acid,
Or its salts) to adjust the pH of the solution to around 3.0-4.5. During the soaking process in the tanning process, the above-mentioned organic composition is injected into the drum before the addition of the chrome tanning agent to penetrate the leather, and then the chrome tanning agent is added to carry out tanning by a conventional method.

In a further aspect of the present invention, the amount of chromium tanning agent used in the factory is reduced, the frequency of exposure of the human body to heavy metal compounds of high concentration is reduced, and the amount of chromium oxide in the factory effluent is reduced. The solution is to solve one of the problems associated with the treatment of wastewater from plants. That is, by the addition of this organic composition, the amount of residual chromium oxide in the waste liquid after tanning (Cr ₂ O ₃ amount) is 90 to 200 ppm, the amount of residual chromium oxide after tanning (Cr ₂ O ₃ amount) Is 4,000 to 8,000 ppm, which is significantly improved. As a result, the amount of chrome tanning agent used in the factory has been reduced compared to before,
It is considered that the amount of residual chromium in the factory effluent after the water squeezing process for tanned leather and leather is significantly reduced, which will contribute greatly to the improvement of the factory effluent treatment. Furthermore, when a highly adsorbent for leather of a chrome tanning agent, which is commercially available recently, is used as a substitute for the organic composition of the present invention, even the most likely commercial product is the residual chromium oxide in the waste liquid after chrome tanning. The amount was 480 ppm.

There is also an example in which the keratin hydrolyzate is used for the adsorption reaction of the chrome tanning agent on the leather as described above, but the keratin hydrolyzate has a wide molecular weight distribution of 2,000 to 20,000, and the hydrolysis Even if the pH of the product is lowered with hydrochloric acid, the pH is 6.5-7.0.
The pH range is less than 4.5 and precipitation tends to occur at pH 4.5 or below. Generally, the pH of a chrome tanning agent solution is about 2.6 to 3.5, so if this keratin hydrolyzate is added before adding the chrome tanning agent, this keratin hydrolyzing agent will react with the chrome tanning agent before it reacts with the leather. It is highly possible that the substance reacts with the chrome tanning agent to cause precipitation. Therefore, a chrome tanning agent is added to the leather and the chrome tanning agent is allowed to penetrate before the keratin hydrolyzate is added. The addition method of this keratin hydrolyzate is the addition of alkali salts, which are generally widely used as a basicity increasing agent in the conventional chrome tanning method (sodium formate, sodium bicarbonate, sodium acetate, sodium polyphosphate, sodium carbonate, etc.). Similarly,
Chromium tanning agents tend to be unevenly adsorbed on the leather surface, and the leather cannot be tanned uniformly. Further, the wide molecular weight distribution of the partially decomposed protein also hinders the uniform penetration of the alkaline hydrolyzate that reacts with the chrome tanning agent into the leather.

The present invention will be further described with reference to the following examples, but the scope of the present invention is not limited to the examples.

[0018]

Example 1 Cow's hair was made of American Steer Fresh and Trimmed raw leather having a weight of 61/63 pounds.

The drum used was a liquid circulation type and a cow hair recovery device was attached during circulation.

Preliminary soaking was carried out, and the weight of the bark having a water content of about 45% was defined as 100%, and the following chemical amounts were calculated based on this as a basis of weighing. twenty five
After adding 0.2% polyoxyethylene alkylphenyl ether as an activator to 200% water by weight at ℃, and using a drum (hereinafter the same) and rotating at a peripheral speed of 30 m / min (the same below) for 5 minutes, Stop for 60 minutes, Rotate for 30 minutes, Stop for 60 minutes, 3
After rotating for 0 minutes, it was drained. 6 with running water of about 400 l / min
After washing with water for 0 minutes and draining, it was subjected to freshening (an operation of removing fat and tightening tissue attached to the surface of the skin).

Preliminary water rinsing The rawhide that had been prewashed with water was immersed in the following aqueous solution, and the following operation was performed.

25%, 200% by weight of water 0.1% Busan 30L (manufactured by Bookman Laboratories Inc .: Buckman Labratories Inc.) 0.1% polyoxyethylene alkylphenyl ether 0.1% sodium hydroxide After rotating for 180 minutes, the above aqueous solution was again used. It was soaked in, and rotated for 10 minutes and stopped for 90 minutes was repeated 7 times. The next morning, it was rotated for 10 minutes and drained. Next, it was rotated and drained with 200% by weight of water at 25 ° C. for 10 minutes, and further drained by rotating with 200% by weight of water at 27 ° C. for 10 minutes.

Alkali treatment (depilation) The weight of the bark having a water content of about 45% after salting was set to 100%, and the following chemical amount was calculated based on this as the basis of weighing.

[0024] The above-prepared raw hide is heated at 27 ° C and 150% by weight.
Was soaked in water and an aqueous solution of 0.1% polyoxyethylene alkyl phenyl ether, rotated for 20 minutes, and stopped for 10 minutes. Then add 3.0% calcium hydroxide and spin for 5 minutes 2
The stop for 0 minutes was repeated twice, and the rotation was continued for another 5 minutes. Then 2.
Add 5% sodium hydrosulfide, rotate for 10 minutes, stop for 20 minutes 2
Repeated times. Further, 0.8% sodium carbonate was added, and rotation for 10 minutes and stop for 20 minutes were repeated twice, and then rotation for 10 minutes was stopped. Finally, water at 27 ° C and 150% by weight was added, and the mixture was rotated for 20 minutes to collect cow hair and then drain it.

The cowhide obtained here was recalcified, rehydrated, soaked and tanned by a conventional method.

[0026]

Example 2 Method for Producing Organic Composition from Cow Hair The cow hair collected in Example 1 was placed in a reactor and rinsed with running water (100 l / min) at 30 ° C. for 60 minutes, and after draining under the same conditions again. Wash with water. The alkali-treated cow hair was used to produce the organic composition of the present invention. That is, first, 1 kg of alkali-treated cow hair was placed in a reactor, 8 liters of 1N sodium hydroxide aqueous solution was further added, and the mixture was heated at 80 ° C. for 24 hours with stirring to obtain an aqueous keratin protein solution. The molecular weight of this protein was about 9,000 by gel filtration.

The reaction solution was cooled and allowed to stand for 1 day. The next day, the reaction solution was heated to 40 ° C., filtered, and the filtrate was decolorized. Then, 2.8 kg of lactic acid was added with stirring to adjust the pH to 3.0 to 3.5.

[0028]

Example 3 Kip skin (American) 17 pounds was used as the chrome-tanned raw hide using the organic composition of the present invention . The amount of the chemicals below was calculated with the weight of the skin thinned to a thickness of 3.0 mm as 100% and the basis of the weight. Pickled,
The steps of lime dipping, plow (3.0 mm) and returning were carried out in the conventional manner.

Immersion of acid In a 25 ° C., 50% by weight water, 8% saline solution, rotation was carried out for 10 minutes. 5% by weight of water containing 0.5% formic acid was further added and the mixture was rotated for 15 minutes. 10% weight water containing 1.0% sulfuric acid was added every 20 minutes in four portions, 2.0% by weight of the organic composition of the present invention was added, and the mixture was rotated for 60 minutes. Finally at 35 ℃
After adding 20% by weight of water and rotating for 7 hours, rotation was repeated every 60 minutes for 10 minutes. The next morning, after rotating for 10 minutes, a mildew proofing agent was added, and after rotating for another 10 minutes, the leather was taken out and spread flat.

The pH of the finally obtained leather is 4.5, the adsorption amount of chromium oxide is 3.8% (the weight when the skin moisture is 14% is 100%), the heat shrink temperature is 98-102 ° C., and the leather is made after tanning. The amount of residual chromium oxide in the waste liquid was 97 ppm, and the color of the waste liquid was almost colorless.
(The waste liquid from the conventional method is dark green blue). This leather is finished by dyeing, greasing, water squeezing, vacuum drying, aging, taste picking, staking, toggling and trimming according to the conventional method, and in the sensory finish inspection of the leather, it is grainy compared with the conventional method. The same in silver standing, the elasticity of the leather is 4 in the 5-point evaluation in the conventional method, whereas the leather treated with the composition of the present invention is 4.
It showed 5 to 5.0.

Claims (1)

Claim: What is claimed is: 1. A method for producing an organic composition that enhances the effect of a chrome tanning agent adsorbing to leather in the chrome tanning step; (a) Cow hair produced in the hair removal step of cowhide. (B) The average molecular weight of the hard protein keratin, which is the main constituent of the treated cow's hair, is about 1 by partially decomposing the protein.
Producing a water-soluble keratin protein in the range of 000 to 36,000; and (c) adding an organic acid or a salt thereof to the water-soluble keratin protein and adjusting the pH to 3.0 to 4.5. Method for producing organic composition.