CN111763782A - Preparation process of white super-soft environment-friendly leather - Google Patents

Abstract

The invention discloses a process for preparing white ultra-soft environment-friendly leather, which comprises the steps of carrying out acid washing, neutralizing, retanning neutralizing and dyeing on the leather subjected to fleshing, wringing, shaving and weighing in sequence, adjusting the pH value by formic acid and oxalic acid during acid washing, carrying out subsequent operation overnight after acid washing, carrying out subsequent operation on the next day, replacing a chrome tanning agent by a chrome-free tanning agent in the retanning process, properly adjusting the process sequence, adjusting the leather property by using the combination of different reagents, carrying out twice neutralizing in the neutralizing process and the retanning neutralizing process to carry out filling and fatliquoring for multiple times step by step, making the ultra-soft leather, and enabling the leather to obtain the performances of bending resistance, yellowing resistance and aging resistance. The invention can be used for preparing leather with better softness and elasticity, and has little pollution to the environment in the production process.

Description

Preparation process of white super-soft environment-friendly leather

Technical Field

The invention relates to the technical field of preparation of environment-friendly leather, in particular to a preparation process of white super-soft environment-friendly leather.

Background

The leather is used as a common basic material in clothes, home furnishings, ornaments and ornaments, is a denatured and non-rotten animal leather product obtained by physical and chemical processing such as unhairing, tanning and the like, and has better hand feeling, elasticity, comfort and air permeability.

In the field of leather for shoes, conventional vamp leather is mainly compact, stiff or medium-soft leather, and has few super-soft leather styles, and the traditional leather preparation process has no higher requirement on environmental protection performance, can generate a large amount of chromium and COD, and can generate certain pressure on the environment.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a preparation process of white super-soft environment-friendly leather, so as to solve the defects in the technical background.

The technical problem solved by the invention is realized by adopting the following technical scheme:

a preparation process of white super-soft environment-friendly leather comprises the following operation steps:

s1 acid washing: the method comprises the following steps of putting raw leather into an acid washing container after fleshing, wringing, shaving and weighing, adding acid washing solution for acid washing, keeping the pH value of the acid washing solution at 3.5-3.8 in the acid washing process, keeping the acid washing temperature at 40-45 ℃, keeping the acid washing time at 80-100 min, draining overnight after the acid washing is completed, and washing before entering the next process;

s2 neutralization: the method comprises two neutralization procedures:

the neutralization solution adopted in the first neutralization process comprises 0.5-0.8 wt% of sodium formate and 0.8-1.2 wt% of neutralized tannin, and the neutralization time is 15-40 min;

in the second neutralization step, 1-1.5 wt% of phenolic resin tannin and 0.5-0.8 wt% of fatliquor are added into the neutralized solution in the first neutralization step, and the neutralization time is 40-60 min;

washing after neutralization;

s3 retanning: adding the neutralized and washed leather material into a retanning container, adding water to submerge the leather material, recording the water addition amount as M, and sequentially treating according to the following sequence:

adding 0.5-0.8 wt% of fatting agent for treatment for 5-6 min;

adding 12-15 wt% of acrylic resin for treatment for 50-80 min;

adding 7-9 wt% of dicyandiamide, 5-6 wt% of animal protein and 12-15 wt% of leather filler for treatment for 60-90 min;

supplementing water for 2-2.5M, and keeping for 8-10 min;

adding formic acid, adjusting the pH value of the solution in the container to 3.5-3.7, and treating for 40-50 min;

adding 1-2 wt% of aldehyde tanning agent, 0.5-1 wt% of animal protein and 0.2-0.3 wt% of fatliquor for treatment for 60 min;

adding 0.3-1 wt% of sodium formate and 0.1-0.3 wt% of white paste for treatment for 25-40 min;

s4 retanning neutralization: the method comprises two times of neutralization treatment, wherein the neutralizing agents added in the two times of neutralization treatment are mixture neutralizing agents, the components and the use amounts are the same, and the mixture neutralizing agents comprise sodium formate, sodium bicarbonate and a leather neutralizing agent which are added according to the proportion of 5:7:18, the sodium bicarbonate and the leather neutralizing agent are directly added into a retanning container during neutralization, the neutralizing agent is added during the first neutralization to adjust the pH value of a solution in the retanning container to 4.5-4.7, the neutralizing agent is added again after 30min of treatment to adjust the pH value of the solution in the retanning container to 6.2-6.5, the neutralization is completed after 60min of reaction, and washing is performed after the neutralization is;

s5 staining: putting the leather which is retanned, neutralized and cleaned into a dyeing container, adding water to submerge the leather, recording the water adding amount as N, and sequentially treating according to the following sequence:

adding 5-7 wt% of a fatting agent and 0.8-1.6 wt% of an acrylic acid polymer tanning agent for treatment for 40-60 min;

adding 4-6 wt% of animal protein, 7-9 wt% of white tannin, 6-8 wt% of white tannin extract and 1-2 wt% of animal fat and oil for treatment for 40-60 min;

adding a dye for dyeing treatment;

supplementing water for 2-2.5M, and keeping for 8-20 min;

adding 0.8-1.2 wt% of animal protein for treatment for 10-20 min;

adding 1-1.2 wt% of a fatting agent for treatment for 30-50 min;

adding 0.8-1.2 wt% of acrylic acid for treatment for 25-35 min

And washing after dyeing is finished to finish the process.

As a further limitation, neutralization, retanning neutralization are all operated with a rotating drum as the vessel.

By way of further limitation, the acid washing solution is preferably a formic acid solution or an oxalic acid solution or a mixed acid solution of formic acid and oxalic acid.

Further, the washing operations in step S1, step S2, and step S4 are all performed with normal temperature water in an amount of three times the amount of 2 to 5 times the amount of the process solution used in the corresponding treatment process.

By way of further limitation, the dyeing process also comprises a color register process after the dyeing process is completed, and the color register process is carried out according to the following modes:

adding a dye which is twice of the dye added in the dyeing process into 250 parts by mass of water for treatment, keeping the water temperature at 55 ℃ for 15min during the treatment, then adding 1.6 parts by mass of formic acid twice, 0.8 part by mass of each time, and 30S between the two times, treating for 15min together, finally adding a stabilizer, keeping for 15min, draining, and washing with water at normal temperature.

Has the advantages that: the preparation process of the white super-soft environment-friendly leather is environment-friendly, the production amount of COD (chemical oxygen demand) in the dyeing waste liquid is reduced without changing the physical property of the leather by improving the process and replacing the chrome tanning agent, and the pollution to the environment in the production process is reduced because the waste liquid does not contain chromium. The prepared environment-friendly leather is soft in leather property, has excellent hand feeling of ultra-softness and high resilience, is resistant to bending and yellowing, excellent in aging resistance, soft and floating, has moderate elasticity and Q feeling, and can effectively meet the requirements of people on ultra-softness and high resilience leather.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

In the examples, the white super soft environment-friendly leather is prepared according to the following steps, the leather has different leather.

In this example, the skin species as the raw material is naepa embryo skin of american male castrate, which is prepared according to the process flow of acid washing → neutralization → retanning → dyeing → chromatography after conventional wringing, shaving and weighing processes, wherein:

in the acid washing process, 3 parts by mass of formic acid and 4 parts by mass of oxalic acid are added into 3000 parts by mass of water to prepare acid washing liquid, the pH value of the acid washing liquid is 3.67, the acid washing liquid is directly used for washing the leather, the acid washing temperature is 42 ℃, and the time duration is 90 min. And after the acid washing is finished, filtering and drying overnight, washing with normal temperature water in an amount which is 3 times that of the next day, and performing a neutralization process after the washing is finished.

The neutralization procedure is carried out in two times, 1 part by mass of sodium formate and 1.5 parts by mass of neutralized tannin are adopted for the first neutralization, 150 parts by mass of water is added for the first neutralization, and the neutralization time is 20 min; and (3) after the first neutralization is finished, adding 2 parts by mass of phenolic resin tannin and 1 part by mass of fatliquor into water for second neutralization, wherein the neutralization time is 50 min. After the neutralization is finished, the mixture is cleaned by 3 times of normal temperature water and then enters a retanning process.

During retanning, leather is added into 70 parts by mass of water, and reagents are added in the following sequence for treatment: adding 0.5 mass part of fatting agent for treatment for 5min → adding 10 mass parts of acrylic resin for treatment for 60min → adding 6 mass parts of dicyandiamide, 4 mass parts of animal protein PB, 10 mass parts of leather filler for treatment for 70min → supplementing 150 mass parts of water for 10min → adding 2.5 mass parts of formic acid for treatment for 45min, wherein the pH value of the solution in the container is 3.6 → adding 4 mass parts of aldehyde tanning agent, 2 mass parts of animal protein PB and 0.5 mass part of fatting agent for treatment for 60min → adding 1 mass part of sodium formate and 0.5 mass part of white paste for treatment for 30 min.

And when retanning is finished, adding a neutralizer into the retanning container for twice neutralization, wherein the neutralizer added during twice neutralization is a mixture neutralizer which has the same components and comprises 0.5 part by mass of sodium formate, 0.7 part by mass of baking soda and 1.8 parts by mass of neutralizer ZR23, after the first part of mixture neutralizer is added for the first time, the pH value of the solution in the retanning container is 4.6, adding a second part of mixture neutralizer again after 30min of treatment, finishing neutralization after the solution in the retanning container reacts for 60min, after neutralization, washing with clean water which is three times the volume of the final solution in the retanning container, washing for 10min, and washing and then performing dyeing.

When dyeing, putting the leather which is retanned, neutralized and cleaned into a dyeing container, adding 70 parts by mass of water, and then adding reagents according to the following sequence for treatment: adding 4 parts by mass of fatting agent, 7 parts by mass of acrylic polymer tanning agent for treatment for 50min → adding 4 parts by mass of animal protein PB, 6 parts by mass of white tannin WB, 5 parts by mass of white tannin extract and 1 part by mass of animal fat for treatment for 50min → adding dye, dyeing according to the corresponding dye dyeing requirement → adding 150 parts by mass of water for holding for 10min → adding 2 parts by mass of animal protein PB for treatment for 15min → adding 2.5 parts by mass of fatting agent SXL-5 for treatment for 40min → adding 2 parts by mass of acrylic acid for treatment for 30min, completing the dyeing process, and washing with clear water with three times of the volume of the final solution in the dyeing container after dyeing neutralization.

In the embodiment, in order to stabilize the dyeing effect, a color registering process is further provided, wherein the color registering process is arranged after the dyeing process, the dye which is twice added in the dyeing process is added into 250 parts by mass of water for treatment, the water temperature is kept at 55 ℃ for 15min during the treatment, then 1.6 parts by mass of formic acid is added twice, 0.8 part by mass of formic acid is added each time, the interval between the two times is 30S, the treatment is carried out for 15min, finally, a stabilizer is added, the treatment is carried out for 15min, water is drained, and the finished product of the ultra-soft environment-friendly leather is obtained by washing the leather with normal-temperature water.

The parameters of two batches of different raw material cowhides prepared by the method in the above embodiment are respectively used as embodiment 2, and the traditional leather tanning process is used as embodiment 1 for comparison, and the parameter results are as follows:

serial number	Content of test	Test method	Example 1	Example 2
					1	Chromium residues of retanning waste liquors	Titration of potassium ferricyanide	98mg/L	N.D
2	COD output of dyeing waste liquor	Titration method of potassium dichromate	16.3kg/T	6.3kg/T
					3	Softness	Softness tester	41（￠25）	60（￠25）
4	Flexing resistance	Bending-resistant detector	10W times of no crack	30W times of no crack
					5	Tensile strength	Strength tensile machine	1.8Kg/mm²	2.5Kg/mm²

From the above table, it can be seen that in the present embodiment, by improving the process, chrome tannin retanning is replaced by various chrome-free tanning agents such as aldehyde tanning agent, synthetic tannin and the like, so as to reduce heavy metal emission, and the leather can be endowed with a soft and compact leather body by the white tannin extract in combination with animal protein PB and fat liquor. Meanwhile, ammonia nitrogen-free materials are adopted in the retanning process. The neutralization tannin replaces ammonium bicarbonate for neutralization, the addition and the discharge of ammonia nitrogen are reduced, the neutralizing agent ZR23 is adopted for subsequent neutralization, sodium bicarbonate, sodium formate and grease are used together, the reagents are good in binding property with leather, the softness of the leather can be effectively improved by being connected in a proper process stage, the softness can be slowly and deeply neutralized and enhanced, and meanwhile, the biodegradation performance is good. The matching of the fatting agent and the grease can improve the absorption rate of the leather, so that the prepared leather is soft and full; the two neutralization processes in the retanning process can be used for filling and fatliquoring for multiple times respectively, so that the penetration and absorption of materials are facilitated, the ultra-soft leather is made, and the leather is endowed with good hand feeling and natural appearance.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (5)

1. A preparation process of white super-soft environment-friendly leather is characterized by comprising the following operation steps:

s1 acid washing: squeezing, shaving and weighing raw leather, putting the raw leather into an acid washing container, adding an acid washing solution for acid washing, keeping the pH value of the acid washing solution at 3.5-3.8 in the acid washing process, keeping the acid washing temperature at 40-45 ℃, keeping the acid washing time for 80-100 min, filtering the raw leather to be dry overnight after the acid washing is finished, and washing the raw leather before entering the next process;

s2 neutralization: the method comprises two neutralization procedures:

the neutralization solution adopted in the first neutralization process comprises 0.5-0.8 wt% of sodium formate and 0.8-1.2 wt% of neutralized tannin, and the neutralization time is 15-40 min;

in the second neutralization step, 1-1.5 wt% of phenolic resin tannin and 0.5-0.8 wt% of fatliquor are added into the neutralized solution in the first neutralization step, and the neutralization time is 40-60 min;

washing after neutralization;

s3 retanning: adding the neutralized and washed leather material into a retanning container, adding water to submerge the leather material, recording the water addition amount as M, and sequentially treating according to the following sequence:

adding 0.5-0.8 wt% of fatting agent for treatment for 5-6 min;

adding 12-15 wt% of acrylic resin for treatment for 50-80 min;

adding 7-9 wt% of dicyandiamide, 5-6 wt% of animal protein and 12-15 wt% of leather filler for treatment for 60-90 min;

supplementing water for 2-2.5M, and keeping for 8-10 min;

adding formic acid, adjusting the pH value of the solution in the container to 3.5-3.7, and treating for 40-50 min;

adding 1-2 wt% of aldehyde tanning agent, 0.5-1 wt% of animal protein and 0.2-0.3 wt% of fatliquor for treatment for 60 min;

adding 0.3-1 wt% of sodium formate and 0.1-0.3 wt% of white paste for treatment for 25-40 min;

s4 retanning neutralization: the method comprises two times of neutralization treatment, wherein the neutralizing agents added in the two times of neutralization treatment are mixture neutralizing agents, the components and the use amounts are the same, and the mixture neutralizing agents comprise sodium formate, sodium bicarbonate and a leather neutralizing agent which are added according to the proportion of 5:7:18, the sodium bicarbonate and the leather neutralizing agent are directly added into a retanning container during neutralization, the neutralizing agent is added during the first neutralization to adjust the pH value of a solution in the retanning container to 4.5-4.7, the neutralizing agent is added again after 30min of treatment to adjust the pH value of the solution in the retanning container to 6.2-6.5, the neutralization is completed after 60min of reaction, and washing is performed after the neutralization is;

s5 staining: putting the leather which is retanned, neutralized and cleaned into a dyeing container, adding water to submerge the leather, recording the water adding amount as N, and sequentially treating according to the following sequence:

adding 5-7 wt% of a fatting agent and 0.8-1.6 wt% of an acrylic acid polymer tanning agent for treatment for 40-60 min;

adding 4-6 wt% of animal protein, 7-9 wt% of white tannin, 6-8 wt% of white tannin extract and 1-2 wt% of animal fat and oil for treatment for 40-60 min;

adding a dye for dyeing treatment;

supplementing water for 2-2.5M, and keeping for 8-20 min;

adding 0.8-1.2 wt% of animal protein for treatment for 10-20 min;

adding 1-1.2 wt% of a fatting agent for treatment for 30-50 min;

adding 0.8-1.2 wt% of acrylic acid for treatment for 25-35 min

And washing after dyeing is finished to finish the process.

2. The process for preparing white super soft environment friendly leather according to claim 1, wherein neutralization, retanning neutralization are all operated with a rotary drum as a container.

3. The process for preparing white super-soft environment-friendly leather according to claim 1, wherein the acid washing solution is formic acid solution or oxalic acid solution or mixed acid solution of formic acid and oxalic acid.

4. The process for preparing white super-soft environment-friendly leather according to claim 1, wherein the washing operations in the steps S1, S2 and S4 are all washing with normal temperature water which is three times of 2-5 times of the process solution used in the corresponding treatment process.

5. The preparation process of the white super-soft environment-friendly leather according to claim 1, characterized by further comprising a color registering process after the dyeing process is completed, wherein the color registering process is carried out as follows:

adding a dye which is twice of the dye added in the dyeing process into 250 parts by mass of water for treatment, keeping the water temperature at 55 ℃ for 15min during the treatment, then adding 1.6 parts by mass of formic acid twice, 0.8 part by mass of each time, and 30S between the two times, treating for 15min together, finally adding a stabilizer, keeping for 15min, draining, and washing with water at normal temperature.