阅读说明：本技术 一种皮革不浸酸鞣制方法 (Non-pickling tanning method for leather ) 是由 杨军子 杨世超 丁吉东 靳龙涛 赵东辉 石贵强 刘兰肖 刘伟 郭玉峰 崔孟超 李 于 2020-11-26 设计创作，主要内容包括：本发明提供一种皮革不浸酸鞣制方法,该方法包括以下步骤：准备：将灰皮称重入鼓,水洗两次后,进行脱灰、脱脂、软化；水洗：鼓中加入冷水降温到20℃,进行水洗；铬鞣：加入铬鞣剂转动4h；加酸：加入甲酸转动30min；分次加酸：分4次加入硫酸,每次加入硫酸后转动30min,之后调节浴液PH值为2.3后,再转90min；加入硫代硫酸钠；分次提碱：分5次加入小苏打,每次加入小苏打后转动30min,之后调节PH值为3.8后,升温到36℃,转动4h,排液、出鼓,出鼓后的半成品经削匀、中和、染色、加油、整饰后形成最终成品,本发明具有减少环境污染,省去浸酸工序且能够保证成品质量指标不降低的特点。(The invention provides a leather pickling-free tanning method, which comprises the following steps: preparing: weighing the ash bark, putting the ash bark into a drum, washing the ash bark with water twice, and then deliming, degreasing and softening the ash bark; washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water; chrome tanning: adding a chrome tanning agent and rotating for 4 hours; adding acid: adding formic acid, and rotating for 30 min; acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, adjusting the pH value of the bath liquid to 2.3, and rotating for 90 min; adding sodium thiosulfate; fractional alkali extraction: adding the baking soda 5 times, rotating for 30min after adding the baking soda each time, then adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid, discharging the liquid, and forming a drum, wherein the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.)

1. A leather pickling-free tanning method is characterized by comprising the following steps:

(1) preparing: weighing the ash bark, putting the ash bark into a drum, washing the ash bark with water twice, and then deliming, degreasing and softening the ash bark;

(2) washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;

(3) chrome tanning: adding chromium salt and rotating for 4 hours, wherein the dosage of the chromium salt is 3-5% of the weight of the ash skin;

(4) adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.4-0.5% of the weight of the ash bark;

(5) acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, adjusting the pH value of bath liquid to 2.3, and rotating for 90min, wherein the dosage of the sulfuric acid added each time is respectively as follows according to the weight percentage of the ash bark: 0.3%, 0.5%;

(6) adding sodium thiosulfate: adding sodium thiosulfate, and rotating for 40min, wherein the use amount of the sodium thiosulfate is 0.8-1% of the weight of the ash bark;

(7) fractional alkali extraction: adding baking soda 5 times, rotating for 30min after adding baking soda each time, adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging, wherein the usage amount of the baking soda added each time is as follows according to the weight percentage of the ash bark: 0.5%, 0.5%.

2. The leather pickling-free tanning method as claimed in claim 1, wherein in the step 7, the semi-finished product after being out of the drum is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.

3. The leather pickling-free tanning method as claimed in claim 1, wherein in the step 3, the bath temperature is 20-25 ℃.

4. The leather pickling-free tanning method as claimed in claim 1, wherein in the step 3, the chromium salt is basic chromium salt.

Technical Field

The invention relates to the technical field of leather clean production, in particular to a leather non-pickling tanning method.

Background

The finished leather needs a complicated and tedious process flow from a leather blank to a finished leather fabric, and twenty or more processes are needed to obtain a final finished product, wherein a blue-leather working section comprises the following key processes of converting an original leather blank into leather: soaking, unhairing, liming, fleshing, softening, washing, pickling, chrome tanning and the like, wherein the pickling process is mainly used for reducing the pH value of the naked skin to be close to the pH value of chrome tanning liquid, preventing the surface from being over tanned, further dispersing collagen fibers, increasing the reactive groups of collagen, further removing non-fibrous protein in the skin, dehydrating the collagen part, enlarging the gaps among the collagen fibers and facilitating the permeation and combination of tanning agent molecules.

The existing tanning pickling and tanning process has some non-negligible environmental problems, mainly including that (1) 8-10% NaCl (salt) is required to be added in the pickling process, if salt is not added, crust leather is acid and swollen, collagen is damaged, and leather can not be made any more, but a large amount of salt is used, so that on one hand, naked leather is dehydrated, and finished leather is flat and not full; on the other hand, the salt in the wastewater is polluted; (2) acid soluble protein and salt soluble protein in the pelts enter the water body in the pickling process, so that the pollution load of COD and BOD in the wastewater is increased; (3) the utilization rate of the chrome tanning agent in the tanning process is low, and the like. The application of the process method makes the subsequent sewage treatment difficult. The emission standard of water pollutants for the leather and fur processing industry (GB 30486-2013) issued by the national environmental protection ministry in 2013 has strict limit values on chloride ions in wastewater directly and indirectly discharged by leather and fur enterprises. Therefore, the tanning process needs to be improved, a non-pickling tanning process is adopted, a pickling process is omitted on the premise that the quality index of a finished product is not lower than that of a conventional process, the environmental pollution (sodium chloride) of the working section is removed, and the cost of raw materials is reduced.

Disclosure of Invention

The invention aims to solve the technical problem of providing a pickling-free tanning process which reduces environmental pollution, omits a pickling process and can ensure that the quality index of a finished product is not reduced.

In order to solve the technical problems, the invention adopts the technical scheme that:

a leather pickling-free tanning method, which comprises the following steps:

(1) preparing: weighing the ash bark, putting the ash bark into a drum, washing the ash bark with water twice, and then deliming, degreasing and softening the ash bark;

(2) washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;

(3) chrome tanning: adding a chrome tanning agent for rotating for 4 hours, wherein the using amount of the chrome tanning agent is 3-5% of the weight of the grey leather;

(4) adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.4-0.5% of the weight of the ash bark;

(5) acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, adjusting the pH value of bath liquid to 2.3, and rotating for 90min, wherein the dosage of the sulfuric acid added each time is respectively as follows according to the weight percentage of the ash bark: 0.3%, 0.5%;

(6) adding sodium thiosulfate: adding sodium thiosulfate, and rotating for 40min, wherein the use amount of the sodium thiosulfate is 0.8-1% of the weight of the ash bark;

(7) fractional alkali extraction: adding baking soda 5 times, rotating for 30min after adding baking soda each time, adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging, wherein the usage amount of the baking soda added each time is as follows according to the weight percentage of the ash bark: 0.5%, 0.5%.

Further, in the step 7, the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.

Further, in the step 3, the temperature of the bath liquid is 20-25 ℃.

Further, in the step 3, the chrome tanning agent is basic chromium salt.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:

the tanning process is improved, the non-pickling tanning process is adopted, the penetration and combination of tanning agent molecules are promoted on the premise of no acid swelling, the pickling process is omitted on the premise of ensuring that the quality index of finished products is not lower than that of the conventional process, the environmental pollution caused by sodium chloride at the working section of the pickling process is removed, and the raw material cost is reduced.

The product obtained by the invention has light blue and smooth grain surface, can resist the temperature of 95-100 ℃, has the leather yield of 100-102 percent, fine grain surface, obvious filling and thickening effects and no change after being stored for one month.

The method omits the pickling process, and after the chrome tanning agent is added, formic acid is added and sulfuric acid is added in several times, so that the formic acid has small molecules and fast permeation, has a masking effect on chrome tanning liquid, can reduce the binding performance of the tanning agent and collagen fibers, can slow down the tanning effect and improve the uniformity of chrome tanning, and can slowly reduce and adjust the pH value through adding the sulfuric acid in several times and rotating, so that the chrome tanning process is carried out, the action time of a strong acid environment is short, and acid swelling can not occur.

According to the invention, sodium thiosulfate is added and used as a reducing agent, dichromate can be reduced into effective trivalent chromium salt, and sodium bicarbonate is added in several times to carry out alkali extraction in several times, so that the pH values of bath solution and a product are improved, and the combination between a tanning agent and collagen fibers is promoted.

Detailed Description

The following detailed description will be provided for the embodiments of the present invention with reference to specific embodiments, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented. Unless otherwise indicated, the techniques employed in the examples are conventional and well known to those skilled in the art, and the reagents and products employed are also commercially available. Various procedures and methods not described in detail are conventional methods well known in the art, and the source, trade name, and if necessary, the constituents of the reagents used are indicated at the first appearance.

Example 1

A leather pickling-free tanning method, which comprises the following steps:

(1) preparing: weighing the ash bark, putting the ash bark into a drum, washing the ash bark with water twice, and then deliming, degreasing and softening the ash bark;

(2) washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;

(3) chrome tanning: adding a chrome tanning agent for rotating for 4 hours, wherein the using amount of the chrome tanning agent is 3 percent of the weight of the grey leather, the chrome tanning agent is basic chromium salt, and the bath temperature is 20 ℃;

(4) adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.4% of the weight of the ash bark;

(5) acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, adjusting the pH value of bath liquid to 2.3, and rotating for 90min, wherein the dosage of the sulfuric acid added each time is respectively as follows according to the weight percentage of the ash bark: 0.3%, 0.5%;

(6) adding sodium thiosulfate: adding sodium thiosulfate, and rotating for 40min, wherein the use amount of the sodium thiosulfate is 0.8% of the weight of the ash bark;

(7) fractional alkali extraction: adding baking soda 5 times, rotating for 30min after adding baking soda each time, adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging, wherein the usage amount of the baking soda added each time is as follows according to the weight percentage of the ash bark: 0.5 percent, 0.5 percent and 0.5 percent, and the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.

Example 2

A leather pickling-free tanning method, which comprises the following steps:

(1) preparing: weighing the ash bark, putting the ash bark into a drum, washing the ash bark with water twice, and then deliming, degreasing and softening the ash bark;

(2) washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;

(3) chrome tanning: adding a chrome tanning agent for rotating for 4 hours, wherein the using amount of the chrome tanning agent is 5 percent of the weight of the grey leather, the chrome tanning agent is basic chromium salt, and the bath temperature is 25 ℃;

(4) adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.5% of the weight of the ash bark;

(5) acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, adjusting the pH value of bath liquid to 2.3, and rotating for 90min, wherein the dosage of the sulfuric acid added each time is respectively as follows according to the weight percentage of the ash bark: 0.3%, 0.5%;

(6) adding sodium thiosulfate: adding sodium thiosulfate, and rotating for 40min, wherein the use amount of the sodium thiosulfate is 1% of the weight of the ash bark;

(7) fractional alkali extraction: adding baking soda 5 times, rotating for 30min after adding baking soda each time, adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging, wherein the usage amount of the baking soda added each time is as follows according to the weight percentage of the ash bark: 0.5 percent, 0.5 percent and 0.5 percent, and the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.

Example 3

A leather pickling-free tanning method, which comprises the following steps:

(1) preparing: weighing the ash bark, putting the ash bark into a drum, washing the ash bark with water twice, and then deliming, degreasing and softening the ash bark;

(2) washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;

(3) chrome tanning: adding a chrome tanning agent for rotating for 4 hours, wherein the using amount of the chrome tanning agent is 4 percent of the weight of the grey leather, the chrome tanning agent is basic chromium salt, and the bath temperature is 23 ℃;

(4) adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.5% of the weight of the ash bark;

(5) acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, adjusting the pH value of bath liquid to 2.3, and rotating for 90min, wherein the dosage of the sulfuric acid added each time is respectively as follows according to the weight percentage of the ash bark: 0.3%, 0.5%;

(6) adding sodium thiosulfate: adding sodium thiosulfate, and rotating for 40min, wherein the use amount of the sodium thiosulfate is 0.9% of the weight of the ash bark;

(7) fractional alkali extraction: adding baking soda 5 times, rotating for 30min after adding baking soda each time, adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging, wherein the usage amount of the baking soda added each time is as follows according to the weight percentage of the ash bark: 0.5 percent, 0.5 percent and 0.5 percent, and the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.

Comparative example 1

A method for pickling and tanning leather, which comprises the following steps:

(1) preparing: weighing the ash bark, putting the ash bark into a drum, washing the ash bark with water twice, and then deliming, degreasing and softening the ash bark;

(2) washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;

(3) pickling: adding sulfuric acid, adjusting the pH value of the bath liquid to 2.3, and rotating for 4 h;

(4) chrome tanning: and adding a chrome tanning agent for rotating for 4 hours, wherein the using amount of the chrome tanning agent is 3-5% of the weight of the grey leather, and the chrome tanning agent is basic chromium salt. The temperature of the bath liquid is 20-25 ℃;

(5) and (3) finished product: and shaving, neutralizing, dyeing, oiling and finishing the semi-finished product after the drum is discharged to form a final finished product.

The main difference between comparative example 1 and examples 1 to 3 is that pickling work is required in advance before chrome tanning, but it is different from the conventional process in that sodium chloride is not added during pickling.

Comparative example 2

A method for pickling and tanning leather, which comprises the following steps:

(1) preparing: weighing the ash bark, putting the ash bark into a drum, washing the ash bark with water twice, and then deliming, degreasing and softening the ash bark;

(2) washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;

(3) pickling: adding sulfuric acid, adding sodium chloride with the amount of 10% of the weight of the ash bark, adjusting the pH value of the bath liquid to 2.3, and rotating for 4 hours;

(4) chrome tanning: and adding a chrome tanning agent for rotating for 4 hours, wherein the using amount of the chrome tanning agent is 3-5% of the weight of the grey leather, and the chrome tanning agent is basic chromium salt. The temperature of the bath liquid is 20-25 ℃;

(5) and (3) finished product: and shaving, neutralizing, dyeing, oiling and finishing the semi-finished product after the drum is discharged to form a final finished product.

Comparative example 2 is a currently common tanning process, and the main difference from examples 1-3 is that a pickling operation is required in advance before chrome tanning, and sodium chloride is added during pickling.

The results of the tests on the content of contaminants in the effluents obtained from the tanning process of examples 1-3 and comparative examples 1-2 and the results of the tests on the properties of the leathers obtained are shown below in table 1:

item	Cl-/（mg/L）	Appearance of the product	High temperature resistance	Rate of leather formation	Storage of
						Example 1	Not detected out	Fine, light blue and smooth grain surface	100℃	100%	Has no change for one month
Example 2	Not detected out	Fine, light blue and smooth grain surface	95℃	100%	Has no change for one month
						Example 3	Not detected out	Fine, light blue and smooth grain surface	98℃	100%	Has no change for one month
Comparative example 1	Not detected out	Surface damage and uneven color	/	Leather without quality requirement	Has no change for one month
						Comparative example 2	18423	Fine, deep blue and smooth grain surface	100℃	100%	Has no change for one month

TABLE 1 comparison of test results

As can be seen from the test results in Table 1, leather meeting the product quality requirements can be obtained by adopting the processes in examples 1-3 and comparative example 2, the crust leather can be rotten and collagen is damaged by adopting the process in comparative example 1, namely sodium chloride is not added in the pickling process, and the leather can not be made, and an ideal product can not be obtained, and in comparative example 2, a large amount of Cl & lt- & gt residues are detected in the waste liquid obtained by the tanning process because sodium chloride is added in the pickling process with the dosage of 10% of the weight of the ash leather.

In conclusion, the tanning process is improved, the pickling-free tanning process is adopted, the penetration and combination of tanning agent molecules are promoted on the premise of no acid swelling, the pickling process is omitted on the premise of ensuring that the quality index of a finished product is not lower than that of a conventional process, the environmental pollution caused by sodium chloride in the workshop section of the pickling process is removed, and the raw material cost is reduced.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.