JPH02123200A - Tanning process - Google Patents

Abstract

PURPOSE:To produce a tanned skin having excellent quality in a short time in high efficiency by immersing untanned hide in lime, defatting the treated hide, immersing in a phosphate buffer solution and tanning the hide by adding an aldehyde. CONSTITUTION:An untanned hide immersed in lime is divided, washed with water, defatted in a solution containing a phosphoric acid salt and a defatting agent and then immersed in a phosphoric acid salt solution to form a buffering region of pH6-7 by the reaction of the phosphoric acid salt and Ca ion in the untanned hide. The hide can be tanned by adding an aldehyde to the above liquid. The aldehyde content of the tanned skin is increased, the thermal shrinkage temperature in the liquid is raised and the total time necessary for the treatment can be shortened by the increased reactivity of the skin and the aldehyde owing to the formation of the buffering region.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for efficiently tanning limed bare skin with aldehyde.

(Prior Art) A conventional method of stamping using aldehyde will be explained below in sections.

■ Washing with water First, the skin is washed with water in a rotating drum to remove dirt from the surface of the skin, which has been limed for the purpose of hair removal.

■ Decalcification and fermentation In this process, in order to remove lime from the skin, degrease it, and soften the skin, the skin in the drum is filled with water, ammonium salts, degreasers, enzymes (softening The above treatment is performed while the drum is rotated.

■Washing with water Next, the skin is washed in a rotating drum.

■Acid soaking After water washing, the skin is soaked in a sulfuric acid solution to make it acidic before aging, but this time is very long (usually about 16 hours), so the skin may swell. be. Therefore, salt is added to the acid solution to prevent swelling.

■The skin, which has been processed beyond aging, is placed in a solution of water, aldehyde, and salt to prevent swelling. The higher the Pl+, the better the reactivity between the peel and aldehyde, but on the other hand, if it becomes alkaline, the black tea will become hard because the peel will only develop at the edges with the skin swollen, so the pH of the solution is preferably between 6 and 7. Therefore, in order to raise the pH of the skin soaked in a strong acidic solution to 6-7,
Baking soda is gradually added to the aldehyde solution. The rinsing is carried out for about 8 hours while the drum containing the skins is rotated, adjusting the pH of the solution in this manner. After that, about 16
For a period of time, the skin is immersed in a mixture of water, salt, aldehyde, and baking soda, thereby making the edge of the skin grow.

The leather made in this way is taken out of the drum,
Red leather products are obtained by aging indoors for 2 to 3 days.

(Problems to be Solved by the Invention) Good soft leather can be obtained by improving the reactivity between aldehyde and leather. As mentioned above, the pH at night is preferably between 6 and 7 in order to maintain the reactivity between aldehydes and skins and to obtain a good black tea with excellent appearance and texture. In the aging process, if you try to increase the pH of the skin by adding baking soda, the pH of the aldehyde solution in which the skin is soaked will rise quickly, but the pH of the skin that has been soaked in acid for a long time will not rise. First, even after being immersed for 16 hours in a baking soda-added aldehyde solution with a pH of 6 to 7, the pH inside the skin was only about 4 to 5. Therefore, the reactivity between aldehyde and skin was not very good. Therefore, the aldehyde content in the black tea obtained was low, and the heat shrinkage temperature in liquid was not very high.

In addition, the conventional method is inefficient because it takes a very long time to prepare the solution, and the manufacturing cost is also high.

In view of the above, an object of the present invention is to provide a method for efficiently producing black tea of excellent quality in a short time.

(Means for Solving the Problems) In order to solve the above problems, the company's method according to the present invention is to divide the lime-pickled skin into parts, wash them with water, and then soak them in a solution containing phosphate and a degreasing agent. After degreasing, the naked skin is immersed in a phosphate solution to form a buffer region of pH 6 to 7 through the reaction of calcium ions in the skin with phosphate;
A feature of this method is that it is cured by adding aldehyde to this liquid.

(Action) A buffer region of P116-7 is formed by the reaction of calcium ions in the limed naked skin with phosphate, so the reactivity between the skin and aldehyde is improved, and the aldehyde content of the bast is increased. In addition, the submerged heat shrinkage temperature can be increased, and the time required for the entire treatment can be shortened.

(Example) Example I and Example 2 of the company-manufactured method according to the present invention, and a comparative example according to the prior art will be explained below in the order of each step. Note that in the following, 100% refers to the total weight of the bare skin of the material.

1) Example I (Manufacture of white leather for gloves) ■ Lime-pickled leather and 30 il% water were added to it in a washing drum, and while rotating for about 5 minutes, the bare skin that had been depilated by liming was washed. Removed dirt, etc. from the surface. After washing with water, this waste water was discharged.

(2) Degreasing 200% water, 1% sodium phosphate and 1% degreaser were added to the skin in the drum, and the drum was rotated for about 30 minutes to degrease the skin. After degreasing, the solution was drained.

■Washing 300% water was added to the skin in the washing drum, and the skin was washed with water while rotating for about 5 minutes. After washing with water, this waste water was discharged.

(2) Phosphate treatment 50% water and 3% sodium phosphate were added to the skin in the drum, and phosphate treatment was performed while rotating for 3 hours. In the method according to the present invention, there is no decalcification step, and the water washing step prior to phosphate treatment is very short at 5 minutes, so the skin contains a lot of lime, and this lime and sodium phosphate A buffer region with a pH of 6 to 7 is formed.

Then, when we observed the cut surface of the skin one hour after the rotation started, we found that
Calcium phosphate (CaHPOa) was formed on the surface layer of the skin, which turned white and became soft, but an unreacted portion remained in the center of the skin. When the cut surface of the skin was observed 3 hours after the start of rotation, calcium phosphate (CaHPO4) was also formed in the center of the skin, and it was confirmed that the reaction was progressing throughout the skin. At this time, the pH of the liquid was 6.6, and the temperature of the liquid was 34°C.

(2) Polishing Furthermore, 2% formaldehyde (35% solution) was added to the above bath solution, and the shoes were rotated for 3 hours before shoe-shoeing. As a result, the temperature of the bath liquid rose to about 45°C, and the pH of the liquid rose to 6.
It became 5.

The black tea was removed from the drum and aged indoors for three days. The heat shrinkage temperature in liquid of the obtained leather was 85°C, and the formaldehyde content it (mg/1 g of leather) was 5.3. Also, the cost of chemicals used in this case (1,000 yen/100 kg of leather)
is 7.4, processing time is 7.1 hours, water amount (m3/leather 1
00kg) was 0.85.

2) Example ■ (Manufacture of white leather for military equipment) Work and process similar to Example ■ except that the amount of formaldehyde (35% solution) added was 1% in the toughening process in Example I above. The conditions were implemented.

The resulting vertical leather had a submerged heat shrinkage temperature of 83° C. and a formaldehyde content (mg/1 g of leather) of 3.6.

The kneading method of the present invention applied to Examples I and H can be applied to all animal skins.

3) Comparative Example (Prior Art) - Washed and limed naked skin was divided into parts, placed in a drum, added with 300% water, and rotated for about 30 minutes to remove dirt.

After washing with water, this waste water was discharged.

■ Add 300% water, 5% ammonium chloride, and 1% degreaser to the skin in the deashing/fermentation drum and rotate for about 30 minutes.Furthermore, add 0.025% enzyme agent to this bath solution and rotate for about 40 minutes. While rotating for a total of 70 minutes, decalcification, defatting, and softening were performed.

After treatment, the solution was drained.

■Washing 300% water was added to the skin in the washing drum, and the skin was washed with water while rotating for about 30 minutes. After washing with water, this waste water was discharged.

■ Add 50% water, 6% salt, and 0.8% sulfuric acid to the skin in the pickling drum, rotate for about 100 minutes, and then soak the skin in this solution for 16 minutes.
The sample was immersed in an acid for a certain period of time to prevent swelling.

After treatment, this liquid was drained.

■Pour 50% toughened water, 3% common salt, and 2% formaldehyde into a drum, and gradually add 1.1% baking soda to the drum while rotating the drum, adjusting the pH of the solution to 6-7. I made a time appointment.

After being left for 16 hours, the vertical leather was taken out from the drum and aged indoors for 3 days.

The submerged heat shrinkage temperature of the leather thus obtained is 5'C.
The formaldehyde content (mg/g of leather) was 3.1. Also, the cost of chemicals used (1,000 yen/leather IQOkg)
is 18. O1 treatment time was 43.8 hours, water 1 (m'/
100 kg of leather) was 1.00.

The following Tables 1 and 2 list the specification values of Examples I, ① and Comparative Examples described above.

Table 1 Heat Shrinkage Temperature in Liquid and Table 2 Manufacturing Cost (Effects of the Invention) As described above, the kneading method of the present invention provides the following effects.

■According to the present invention, a buffer region of pH 6 to 7 is formed by the reaction between weakly acidic sodium phosphate and calcium ions in naked skin, and the reactivity between the skin and formaldehyde is improved, so the blushing process In the present invention, the amount of formaldehyde added to the solution is 1% (Example ■) or 2% (Example I), which is less than or the same as that of the conventional method (Comparative example = 2%). First, the formaldehyde content in the soft leather obtained by the present invention is higher than that obtained by the conventional method.

■According to the present invention, the reactivity between the peel and formaldehyde is improved, so the temperature of black tea's submerged heat shrinkage is 83-85°C.
The heat resistance is nearly 10°C higher than that of bast grass produced by conventional methods.

(2) Processing time can be dramatically shortened to about 1/6 of the conventional method.

(2) The preparation time for the solution is short, and since phosphate is added, the pH of the solution is between 6 and 7, so the swelling of the skin does not progress and salt is not necessary. In addition, enzyme agents as softeners,
There is no need for ammonium chloride as a deashing agent, and no need for PI (baking soda for adjustment) of the toughening solution.Therefore, chemical costs can be significantly reduced.

Claims (1)

[Claims] After dividing the limed skin and washing it with water, it is degreased in a solution containing phosphate and a degreaser, and then the skin is soaked in a phosphate solution to remove calcium ions and phosphates in the skin. A tanning method in which a buffer region of pH 6 to 7 is formed by reaction with the liquid, and tanning is performed by adding aldehyde to this solution.