CN115595387B

CN115595387B - Efficient leather production method based on aldehyde tanning agent

Info

Publication number: CN115595387B
Application number: CN202211301958.5A
Authority: CN
Inventors: 丁伟; 庞晓燕; 丁志文
Original assignee: China Leather and Footwear Research Institute Co Ltd; China Leather and Footwear Research Institute Co Ltd Wenzhou Branch
Current assignee: China Leather and Footwear Research Institute Co Ltd; China Leather and Footwear Research Institute Co Ltd Wenzhou Branch
Priority date: 2022-10-24
Filing date: 2022-10-24
Publication date: 2023-10-13
Anticipated expiration: 2042-10-24
Also published as: CN115595387A

Abstract

The invention belongs to the field of leather manufacturing, and discloses a high-efficiency leather production method based on an aldehyde tanning agent. The method comprises the following steps: the crust leather is obtained by using gray leather or pickling leather as a raw material, tanning the gray leather or pickling leather by using an aldehyde tanning agent, and then adding dyeing and finishing materials into the raw material in a same bath for wet finishing and drying. The invention designs a tanning-wet finishing integrated one-pot chromium-free leather production technology based on the unique permeability and reactivity of the screened aldehyde tanning agent, and can simultaneously endow leather with high wet heat stability and excellent physical sensory properties through the organic collocation of wet finishing materials and the cooperative control of process conditions; the tanning-wet finishing one-pot leather high-efficiency production technology provided by the invention can save the use amount of leather materials to a certain extent, and more importantly, greatly shortens the production and processing period of leather, remarkably reduces the discharge amount of waste water and is beneficial to boosting the carbon emission reduction of the leather industry.

Description

Efficient leather production method based on aldehyde tanning agent

Technical Field

The invention belongs to the field of leather manufacturing, and particularly relates to a high-efficiency leather production method based on an aldehyde tanning agent.

Background

Leather production mainly comprises three major stages of preparation, tanning and finishing. The tanning section is the most critical, and the tanning section converts the hide which is not resistant to microorganisms and chemical agents into leather which is resistant to heat, chemical agents and microorganisms, and simultaneously endows leather crust with certain mechanical processing performances such as slicing, leather grinding and the like; finishing stations have a critical impact on the quality, performance and style of the final leather product. Currently, the most dominant method for tanning leather is still a chrome tanning method, but the sustainable development of the leather industry is severely restricted by pollution of chromium-containing wastewater and solid wastes generated by the chrome tanning method. Against this background, the development of chrome-free tanning technology to produce chrome-free leather has become a recognized primary task in the worldwide leather industry. In addition, the production of leather has the problems of long period and large water consumption because of the total number of working procedures. This undoubtedly reduces the production efficiency of the leather and increases the pollution load of the leather production to the environment. Therefore, from the perspective of organic cooperation of the tanning section and the finishing section, the development of a tanning-wet finishing integrated one-pot method chromium-free leather production technology has important significance for promoting the chromium-free leather industry and is also a direction with great social benefit, environmental benefit and economic value.

However, based on the leather tanning agents currently used, the tanning process is slow first, it is difficult to complete the tanning in a short time and it is ensured that the leather grain has an excellent fineness due to the mass transfer between the leather collagen fibers and the reactivity of the tanning agent. Secondly, tanned crust leather usually needs to be retanned, dyed and fatliquored after operations of setting up, rinsing, neutralization and the like, and crust leather is produced. The process can involve multiple bath changing operations, so that a large amount of wastewater is generated and discharged, and most of the wastewater contains high-concentration organic matters and heavy metal ions, so that the treatment difficulty is high, the sewage treatment cost of leather enterprises is increased, and potential management risks are brought.

Disclosure of Invention

The invention aims at: aiming at the problems of chromium pollution, complicated production process, time consumption and water consumption of the conventional leather production method, the efficient leather production method based on the aldehyde tanning agent is provided. The invention can produce chrome-free tanning leather products with excellent shrinkage temperature and physical and organoleptic properties in a short time by the organic cooperation of tanning agent, wet finishing material and working procedure. The invention does not use the leather chemical material containing chromium in the whole production process. Therefore, compared with the existing leather production technology, the invention can thoroughly eliminate chromium pollution, has higher cleaning degree, and simultaneously has short time consumption and low sewage discharge.

In order to achieve the above purpose, the present invention proposes the following technical solutions:

the efficient leather production method based on the aldehyde tanning agent comprises the following steps:

the crust leather is obtained by using gray leather or pickling leather as a raw material, tanning the gray leather or pickling leather by using an aldehyde tanning agent, and then adding dyeing and finishing materials into the raw material in a same bath for wet finishing and drying.

Preferably, when the raw material is gray skin, 50% -80% of water and 2% -8% of aldehyde tanning agent are added according to the weight of the gray skin for tanning, and after finishing wet finishing in the same bath, 200% -400% of water is added for washing, liquid control and drying;

when the raw materials are pickling leather, 50% -80% of pickling solution and 2% -8% of aldehyde tanning agent are added according to the weight of 2 times of the pickling leather for tanning, and after one-bath wet finishing is finished, 200% -400% of water is added for washing, and the solution is controlled and dried.

Preferably, the aldehyde tanning agent comprises any one or more of a synthetic aldehyde tanning agent and a bio-based aldehyde tanning agent;

preferably, the synthetic aldehyde tanning agent includes, but is not limited to, TWT and/or TWS aldehyde tanning agent;

preferably, the bio-based aldehyde tanning agent comprises, but is not limited to, any one or more of dialdehyde starch, dialdehyde sodium alginate, dialdehyde carboxymethylcellulose sodium, dialdehyde xanthan gum, dialdehyde cyclodextrin, dialdehyde polysaccharide such as dialdehyde methyl glucoside, dialdehyde oligosaccharide and dialdehyde small molecule saccharide.

Preferably, after the aldehyde tanning agent is added, the tanning agent is rotated for 0-2 h, the temperature is raised to 35-45 ℃, meanwhile, the pH of the bath liquid is controlled to be 7.5-8.5, and the tanning is completed after 2-4 h.

Preferably, the wet finishing is that a conventional retanning agent, a dye and a fatliquoring agent are sequentially added into the tanning bath liquid for one-bath wet finishing, and the total rotation time is 5-6 hours.

Preferably, the wet finishing is that a fatliquoring agent, a conventional retanning agent and a dye are sequentially added into the tanning bath liquid for one-bath wet finishing, and the total rotation time is 5-6 hours.

Preferably, the conventional retanning agent includes, but is not limited to, any one or more of an acrylic retanning agent, an amino resin retanning agent, a plant tannin extract, a synthetic tanning agent.

Preferably, the dosage of the conventional retanning agent is 5% -15%, the dosage of the dye is 2% -4%, and the dosage of the fatliquoring agent is 6% -15%.

Preferably, the specific method of wet finishing is as follows: directly adding an acrylic resin retanning agent into the tanning bath, rotating for 1 h, adding an amino resin retanning agent, continuing rotating for 1 h, adjusting the pH of the bath to 5.5-6.5, and rotating for 0.5 h; adding vegetable tannin extract, synthetic tanning agent and dye, and rotating for 1-2 h; then adding a fatting agent, controlling the temperature to be 50 ℃, rotating for 1 h, adjusting the pH of the bath liquid to be 3.6-3.8, and rotating for 0.5 h; or (b)

Directly adding a fatliquor into tanning bath, controlling the temperature to be 50 ℃, rotating 1 h, controlling the bath temperature to be 35-45 ℃, then adding an acrylic resin retanning agent, rotating 1 h, adding an amino resin retanning agent, continuously rotating 1 h, adjusting the pH of the bath to be 5.5-6.5, and rotating 0.5 h; adding vegetable tannin extract, synthetic tanning agent and dye, and rotating for 1-2 h; then adjusting the pH of the bath liquid to 3.6-3.8, and rotating 0.5-h.

Preferably, a fixing agent is added into the bath after the wet finishing is finished, and after the bath is rotated for 1 to 2 hours, the crust leather is obtained after liquid control, water washing, liquid control again and drying.

Preferably, the fixing agent is any one or more of aluminum sulfate octadecanoate and chromium-free complex tanning agents; the addition amount of the fixing agent is 0.5% -2% based on the weight of ash skin or 2 times of pickled skin.

The invention can control the types and the amounts of retanning agents, dyes and fatliquoring agents according to the types and the corresponding requirements of leather raw materials (such as sheepskin, cowhide and the like) and leather products (such as vamp leather, clothing leather and the like), and can play roles in regulating and controlling the performances and styles of leather products, such as improving softness, increasing fullness, reducing position difference, improving dyeing fastness, mechanical strength and the like.

The technical scheme provided by the invention has the following advantages:

(1) The invention designs a tanning-wet finishing integrated one-pot chromium-free leather production technology based on the unique permeability and reactivity of the screened aldehyde tanning agent, and can simultaneously endow leather with high wet heat stability and excellent physical sensory properties through the organic collocation of wet finishing materials and the cooperative control of process conditions;

(2) The tanning-wet finishing one-pot leather high-efficiency production technology provided by the invention can save the use amount of leather materials to a certain extent, and more importantly, greatly shortens the production and processing period of leather, remarkably reduces the discharge amount of waste water and is beneficial to boosting the carbon emission reduction of the leather industry;

(3) The bio-based aldehyde tanning agent adopted by the invention is prepared by taking renewable glycosyl biomass as a raw material, has excellent sustainability, and can produce a chromium-free leather product through the synergistic collocation of wet finishing materials, so that the technical scheme provided by the invention can be used for manufacturing ecological leather.

Drawings

FIG. 1 (a) is a graph comparing the time consumption (tanning and wet finishing process) of processing 1 ton of pelt (in terms of ash weight) using the technique provided in example 1 of the present invention, the water consumption, and the time consumption (tanning and wet finishing process) of processing 1 ton of pelt (in terms of ash weight) using the conventional leather production method provided in comparative example 1;

FIG. 1 (b) is a photograph of grain of a crust leather processed using the technique provided in example 1;

FIG. 1 (c) is a photograph of grain of a crust leather processed using the technique provided in comparative example 3.

Detailed Description

The present invention will now be described in detail with reference to specific examples, which are given herein for further illustration only and are not to be construed as limiting the scope of the invention, since numerous insubstantial modifications and adaptations thereof will now occur to those skilled in the art in light of the foregoing disclosure.

The first embodiment provided by the invention is a high-efficiency leather production method based on aldehyde tanning agent, comprising the following steps:

Specifically, when the raw material is gray skin, 50% -80% of water and 2% -8% of aldehyde tanning agent are added according to the weight of the gray skin for tanning, and after finishing wet finishing in the same bath, 200% -400% of water is added for washing, liquid control and drying;

when the raw material is pickling leather, 50% -80% of pickling solution and 2% -8% of aldehyde tanning agent are added by 2 times of the weight of the pickling leather for tanning, and after finishing wet finishing in the same bath, 200% -400% of water is added for washing, and the solution is controlled and dried.

The step of using the gray skin as a raw material refers to using the gray skin after the sheet skin as a raw material, and performing one-pot tanning and wet finishing after the treatment by a softening process.

Aiming at the problems of chromium pollution, complicated production process, time consumption and water consumption in the conventional leather production method, the leather production process is improved through the organic synergy of materials and processes, firstly, the unique permeability (the molecular weight of the tanning agent is low or the molecular weight distribution of the tanning agent is wide) of the retorted synthetic aldehyde tanning agent and the biological aldehyde tanning leather in the leather is utilized, the rapid permeation can be carried out among the multi-stage structures of the leather collagen fibers, the structure of part of macromolecular biological aldehyde tanning agent can be changed under the condition of high tanning pH, the molecular size is reduced, the permeability and the reactivity (the reaction rate is controlled by the temperature and the pH are increased), meanwhile, the convergence of the tanning agent molecules to the leather collagen fibers is mild, the problem of rough leather surface is not caused), the softened gray leather or the pickled pelt is subjected to rapid tanning, the shrinkage temperature of the leather blank can be raised to 78-85 ℃ within 2-6 h, and the flat grain surface of the leather is ensured. Then, based on the structural characteristics of the synthetic aldehyde tanning agent and the bio-based aldehyde tanning and the advantage of good compatibility of the tanning agent and common wet finishing materials, the wet finishing is carried out pertinently. Through the interconnection and combination of the materials, the fixation of the conventional wet finishing material on the surface and the inside of crust leather is enhanced, and meanwhile, the remarkable retanning of the aldehyde tanning agent in the wet finishing process is avoided, so that the finally obtained leather product has excellent comprehensive performance.

The wet finishing process provided by the invention is different from the conventional multiple bath exchanging process, and is characterized in that wet finishing materials are directly added into tanning bath liquid, one-bath filling, dyeing, fatliquoring and/or fixing are carried out, so that 'one-pot' preparation from gray leather or acid leather to crust leather is realized, and then a final clean crust leather product is obtained through water washing. In addition, the tanning and wet finishing water consumption of the present invention is only up to 1.8 times the tare weight, plus the water consumption of the water-washed crust leather, which amounts to up to 5.8 times the tare weight.

As some preferred embodiments, the aldehyde tanning agent comprises any one or more of a synthetic aldehyde tanning agent and a bio-based aldehyde tanning agent; more preferably, the synthetic aldehyde tanning agent includes, but is not limited to, a TWT and/or TWS aldehyde tanning agent; the bio-based aldehyde tanning agent comprises any one or more of dialdehyde starch, dialdehyde sodium alginate, dialdehyde carboxymethyl cellulose sodium, dialdehyde xanthan gum, dialdehyde cyclodextrin, dialdehyde methyl glucoside and other dialdehyde polysaccharide, dialdehyde oligosaccharide and dialdehyde micromolecular saccharide.

The specific tanning method after adding aldehyde tanning agent comprises the following steps: and rotating for 0-2 h, heating to 35-45 ℃, controlling the pH of the bath liquid to 7.5-8.5, and rotating for 2-4 h to finish tanning.

For wet finishing, the wet finishing is directly carried out in the same bath after the tanning is finished, and the wet finishing can be carried out by sequentially adding a conventional retanning agent, a dye and a fatliquoring agent into a rotary drum for retanning, dyeing and fatliquoring, wherein the total rotation time is 5-6 h; or adding a conventional fatliquoring agent, a retanning agent and a dye into the rotary drum in sequence to carry out fatliquoring, retanning and dyeing, wherein the total rotation time is 5-6 h.

In the wet finishing process, the dosage of the conventional retanning agent is 5% -15%, the dosage of the dye is 2% -4%, and the dosage of the fatliquoring agent is 6% -15%. These amounts are measured on a raw material basis, based on the weight of the ash when the raw material is ash, and on a weight 2 times the weight of the pickled skin when the raw material is pickled skin.

After the wet finishing, a certain amount of fixing agent can be added into the bath after the wet finishing treatment as required, the bath is rotated for 1-2 hours, and then the subsequent liquid control, water washing and liquid control again are carried out, so that crust leather is obtained after drying. As a preferred embodiment, the fixing agent is any one or more of aluminum sulfate octadecanoate and chromium-free complex tanning agents; the addition amount of the fixing agent is 0.5% -2% based on the initial ash weight.

As some embodiments, the method of wet finishing may be: adding a certain amount of acrylic resin retanning agent dissolved by 50% water into a rotary drum, rotating for 1 h, adding amino resin retanning agent, continuously rotating for 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 5.5-6.5, and rotating for 0.5 h; adding a certain amount of plant tannin extract, synthetic tanning agent and dye, and rotating for 1-2 h; then adding a certain amount of a fatting agent which is heated and hydrated by 50%, controlling the temperature to be 50 ℃, rotating 1 to h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6 to 3.8, and rotating 0.5 to h.

As other embodiments, the wet finishing method may also be: adding a certain amount of a fatliquor which is heated and hydrated by 50% into a rotary drum, controlling the temperature to be 50 ℃, rotating 1 h, controlling the bath temperature to be 35-45 ℃, then adding an acrylic resin retanning agent which is dissolved by 50% of water, rotating 1 h, adding an amino resin retanning agent, continuing rotating 1 h, adding a certain amount of formic acid, adjusting the pH of the bath to be 5.5-6.5, and rotating 0.5 h; adding a certain amount of plant tannin extract, synthetic tanning agent and dye, and rotating for 1-2 h; and then adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6-3.8, and rotating by 0.5-h.

In order to make the invention clearer, the following specific examples are used for describing the efficient leather production method and effect based on the aldehyde tanning agent.

It should be noted that, in the following specific examples: 1) The shrinkage temperature of crust leather is measured by adopting a shrinkage temperature meter; 2) The mechanical strength of crust leather is measured by a high-speed rail servo control tensile testing machine; 3) The softness of crust leather is measured by a softness meter; 4) The fullness of crust leather was measured by compression-rebound energy method, and then rated with good medium difference.

The wet finishing materials used in the examples and comparative examples are all exemplified materials, and are not limiting of the present invention, and specific information thereof is as follows: acrylic resin retanning agents (A33, RF-15), amino resin retanning agents (DD 42, DD 43) and fatliquoring agents (HF, FS-95) are leather chemical materials produced by Sichuan Daway science and technology Co., ltd; the wattle extract (TJ-R228), the Tara extract (TJ-R231), the chrome tanning agent (TJ-T125), the chromium-free complex tanning agent (TWLZ) and the synthetic aldehyde tanning agent (TWT, TWS) are leather chemical materials produced by Sichuan Tingjiang new materials Co., ltd. The synthetic tanning agents (JLE and JAN) are leather chemical materials produced by Zhejiang chemical industry Co., ltd. The leather dyes (leather palm E5G, leather palm S-EDK, leather red AM and leather yellow MR) are leather chemical materials produced by Jiangsu sandisk corporation.

Example 1

The sheep gray skin after the sheet skin is used as a raw material, 50% of water and 4% of dialdehyde methyl glucoside are added into a rotary drum according to the weight of the gray skin after being treated by a softening process, the temperature is raised to 45 ℃, the pH of bath liquid is controlled to be 7.5, and the rotary drum is rotated by 2 h; adding 2% of A33 and 4% of RF-15 into a rotary drum, dissolving the two materials with 50% of water, adding the two materials, rotating for 1 h, adding 2% of DD42 and 2% of DD43, continuing rotating for 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 5.5, and rotating for 0.5 h; adding 4% of TJ-R228, 1% of JLE and 4% of leather palm E5G, and rotating for 2 h; then adding 5% of HF and 5% of FS-95, dissolving the two materials with 50% of hot water, adding the two materials, controlling the temperature to be 50 ℃, rotating 1 to h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6 to 3.8, rotating 0.5 to h, and controlling the liquid; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Example 2

The pickling sheep skin is taken as a raw material, 80% of pickling solution and 8% of dialdehyde sodium alginate are added into a rotary drum according to the weight of 2 times of the pickling sheep skin, the temperature is raised to 40 ℃, the pH of the bath solution is controlled to be 8.0, and the rotary drum is rotated for 3 h; adding 1% of A33 and 2% of RF-15 into a rotary drum, dissolving the two materials with 50% of water, adding the two materials, rotating 1 h, adding 1% of DD42 and 1% of JLE, continuously rotating 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 6.0, and rotating 0.5 h; adding 2% of leather palm S-EDK, and rotating for 1 h; then adding 3% of HF and 3% of FS-95, dissolving the two materials with 50% of hot water, adding the two materials, controlling the temperature to be 50 ℃, rotating 1 to h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6 to 3.8, and rotating 0.5 to h; adding 1% of aluminum sulfate octadecanoate into the bath after the wet finishing treatment, and controlling the bath after rotating 1 h; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Example 3

Taking the cowhide ash skin after the sheet skin as a raw material, adding 50% of water and 8% of dialdehyde starch into a rotary drum according to the weight of the ash skin after the cowhide ash skin is treated by a softening process, heating to 40 ℃, controlling the pH of bath liquid to be 8.5, and rotating for 4 h; adding 5% of HF and 5% of FS-95 into a rotary drum, dissolving the HF and the FS-95 in 50% of hot water, controlling the temperature to be 50 ℃, and controlling the bath temperature to be 35 ℃ after rotating 1 h; then adding 1% of A33 and 2% of RF-15, dissolving the two with 50% of water, adding the two, rotating 1 h, adding 1% of DD42 and 1% of DD43, continuing to rotate 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 6.5, and rotating 0.5 h; adding 2% of TJ-R228, 1% of JLE and 4% of leather yellow MR, and rotating by 1.5 h; then adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6-3.8, rotating 0.5-h, and controlling the liquid; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Example 4

The method comprises the steps of taking pickling sheep skin as a raw material, adding 50% of pickling solution and 6% of dialdehyde carboxymethyl cellulose sodium into a rotary drum according to the weight of 2 times of the pickling sheep skin, heating to 45 ℃, controlling the pH of the bath solution to be 8.5, and rotating for 4 h; adding 5% of HF and 10% of FS-95 into a rotary drum, dissolving the HF and the FS-95 in 50% of hot water, controlling the temperature to be 50 ℃, and controlling the bath temperature to be 40 ℃ after rotating 1 h; then adding 1% of A33 and 2% of RF-15, dissolving the two with 50% of water, adding the two, rotating 1 h, adding 1% of DD42 and 1% of JAN, continuing to rotate 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 5.5, and rotating 0.5 h; adding 1% of TJ-R231 and 3% of leather red AM, and rotating 2 h; then adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6-3.8, and rotating by 0.5-h; adding 2% TWLZ into the bath after the wet finishing treatment, and controlling the bath after rotating 2 h; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Example 5

Taking the cowhide ash skin after the sheet skin as a raw material, adding 60% of water and 2% of TWS into a rotary drum according to the weight of the ash skin after the cowhide ash skin is treated by a softening process, rotating 2 h, heating to 35 ℃, controlling the pH of bath liquid to be 8.5, and rotating 4 h; adding 5% of HF and 5% of FS-95 into a rotary drum, dissolving the HF and the FS-95 in 50% of hot water, controlling the temperature to be 50 ℃, and controlling the bath liquid temperature to be 45 ℃ after rotating 1 h; then adding 2% of A33 and 2% of RF-15, dissolving the two with 50% of water, adding the two, rotating 1 h, adding 1% of DD42 and 1% of DD43, continuing to rotate 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 6.0, and rotating 0.5 h; adding 4% of TJ-R228, 2% of JLE and 2% of leather yellow S-EDK, and rotating 2 h; then adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6-3.8, rotating 0.5-h, and controlling the liquid; adding 300% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Example 6

The pickling sheep skin is taken as a raw material, 60% of pickling liquid and 4% of dialdehyde cyclodextrin are added into a rotary drum according to the weight of 2 times of the pickling sheep skin, the temperature is raised to 40 ℃, the pH of the bath liquid is controlled to be 8.0, and the rotary drum is rotated for 4 h; adding 2% of A33 and 2% of RF-15 into a rotary drum, dissolving the two materials with 50% of water, adding the two materials, rotating for 1 h, adding 1% of DD42 and 1% of DD43, continuing to rotate for 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 6.0, and rotating for 0.5 h; adding 4% of TJ-R228 and 2% of leather red E5G, and rotating 1 h; then adding 10% of HF and 5% of FS-95, dissolving the two materials with 50% of hot water, adding the two materials, controlling the temperature to be 50 ℃, rotating 1 to h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6 to 3.8, and rotating 0.5 to h; adding 0.5% aluminum sulfate octadecanoate into the bath after the wet finishing treatment, and controlling the bath after rotating for 1 h; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Example 7

Taking the cowhide ash skin after the sheet skin as a raw material, adding 50% of water and 8% of dialdehyde xanthan gum into a rotary drum according to the weight of the ash skin after the cowhide ash skin is treated by a softening process, heating to 40 ℃, controlling the pH of bath liquid to be 8.5, and rotating for 4 h; adding 3% of HF and 3% of FS-95 into a rotary drum, dissolving the HF and the FS-95 in 50% of hot water, controlling the temperature to be 50 ℃, and controlling the bath temperature to be 35 ℃ after rotating 1 h; then adding 1% of A33 and 2% of RF-15, dissolving the two with 50% of water, adding the two, rotating 1 h, adding 1% of DD42 and 1% of DD43, continuing to rotate 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 6.0, and rotating 0.5 h; adding 4% of TJ-R228, 2% of TJ-R231, 1% of JLE and 3% of leather yellow MR, and rotating for 2 h; then adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6-3.8, and rotating by 0.5-h; adding 1.5% TWLZ into the bath after the wet finishing treatment, and controlling the bath after rotating 1.5 h; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Example 8

After the goat ash skin after the sheet skin is treated by a softening process, 80% of water and 6% of dialdehyde methyl glucoside are added into a rotary drum according to the weight of the ash skin, the temperature is raised to 45 ℃, and meanwhile, the pH of bath liquid is controlled to be 8.0, and the rotary drum is rotated for 3 h; adding 2% of A33 and 2% of RF-15 into a rotary drum, dissolving the two materials with 50% of water, adding the two materials, rotating for 1 h, adding 1% of DD42 and 1% of DD43, continuing to rotate for 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 5.5, and rotating for 0.5 h; adding 4% of TJ-R228 and 2% of leather palm S-EDK, and rotating for 1.5 h; then adding 4% of HF and 4% of FS-95, dissolving the two materials with 50% of hot water, adding the two materials, controlling the temperature to be 50 ℃, rotating 1 to h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6 to 3.8, rotating 0.5 to h, and controlling the liquid; adding 200% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Example 9

The method comprises the steps of taking pickled goat skin as a raw material, adding 50% of pickling solution, 6% of dialdehyde sodium alginate and 2% of dialdehyde methyl glucoside into a rotary drum according to the weight of 2 times of the pickling goat skin, heating to 35 ℃, controlling the pH of the bath solution to be 8.5, and rotating for 4 h; adding 3% of A33 into the rotary drum, dissolving with 50% of water, adding, rotating for 1 h, adding 1% of DD42 and 2% of JLE, continuing to rotate for 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 6.0, and rotating for 0.5 h; adding 4% of TJ-R228, 2% of TJ-R231 and 2% of leather red AM, and rotating by 1 h; then adding 5% of HF and 5% of FS-95, dissolving the two materials with 50% of hot water, adding the two materials, controlling the temperature to be 50 ℃, rotating 1 to h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6 to 3.8, and rotating 0.5 to h; adding 1% of aluminum sulfate octadecanoate into the bath after the wet finishing treatment, and controlling the bath after rotating 2 h; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Example 10

Taking the cowhide ash skin after the sheet skin as a raw material, adding 50% of water, 4% of dialdehyde methyl glucoside and 1% of TWS into a rotary drum according to the weight of the ash skin after being treated by a softening process, rotating 1 h, heating to 40 ℃, controlling the pH of bath liquid to be 8.0, and rotating 4 h; adding 15% of HF into a rotary drum, heating to 50% for hydration, controlling the temperature to 50 ℃, and controlling the bath liquid temperature to 35 ℃ after rotating 1 h; then adding 4% of RF-15, dissolving with 50% of water, adding, rotating for 1 h, adding 1% of DD42 and 1% of DD43, continuing to rotate for 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 6.0, and rotating for 0.5 h; adding 4% of TJ-R228, 4% of JLE and 2% of leather palm S-EDK, and rotating for 2 h; then adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6-3.8, rotating 0.5-h, and controlling the liquid; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Example 11

Taking the cowhide ash skin after the sheet skin as a raw material, adding 50% of water, 2% of TWT and 2% of TWS into a rotary drum according to the weight of the ash skin after being treated by a softening process, rotating 2 h, heating to 40 ℃, controlling the pH of bath liquid to be 8.0, and rotating 4 h; adding 5% of HF and 5% of FS-95 into a rotary drum, dissolving the HF and the FS-95 in 50% of hot water, controlling the temperature to be 50 ℃, and controlling the bath temperature to be 35 ℃ after rotating 1 h; then adding 1% of A33 and 2% of RF-15, dissolving the two with 50% of water, adding the two, rotating 1 h, adding 1% of DD42 and 1% of DD43, continuing to rotate 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 6.0, and rotating 0.5 h; adding 4% of TJ-R228, 2% of JLE and 2% of leather palm S-EDK, and rotating 2 h; then adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6-3.8, rotating 0.5-h, and controlling the liquid; adding 300% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Example 12

Adding 50% of pickling solution and 4% of TWS into a rotary drum by taking pickling goat skin as a raw material and 2 times of the pickling solution, heating to 35 ℃, controlling the pH of the bath solution to be 8.5, and rotating for 4 h; adding 2% of A33 and 2% of RF-15 into a rotary drum, dissolving the two materials with 50% of water, adding the two materials, rotating for 1 h, adding 2% of DD42 and 2% of JAN, continuing to rotate for 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 6.0, and rotating for 0.5 h; adding 4% of TJ-R228, 1% of TJ-R231 and 2% of leather red AM, and rotating for 2 h; then adding 4% of HF and 4% of FS-95, dissolving the two materials with 50% of hot water, adding the two materials, controlling the temperature to be 50 ℃, rotating 1 to h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6 to 3.8, and rotating 0.5 to h; adding 1.5% of aluminum sulfate octadecanoate into the bath after the wet finishing treatment, and controlling the bath after rotating for 2 h; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Comparative example 1 existing conventional tanning process

Adding 100% of pickling solution and 8% of chrome tanning agent TJ-T125 into a rotary drum by 2 times of the pickling sheep skin serving as a raw material, rotating at normal temperature for 4 h, slowly adding sodium bicarbonate (10 times of hydration), adjusting the pH of the bath solution to 4.0, rotating for 0.5 h, heating to 40 ℃, continuously rotating for 4 h, and stopping the drum overnight; after turning 0.5 to h the next day, controlling the liquid, discharging the liquid out of the drum, and carrying out bonding 24 to h to obtain tanned leather crust; the tanned leather is cut evenly, weighed, then added into a rotary drum, 400 percent of water and 1 percent of formic acid are added, and the rotary drum is rotated for 1 h at 40 ℃ and controlled; 400% of water, 1% of sodium formate and 1% of sodium bicarbonate are added into a rotary drum, the rotary drum is rotated for 1 h at 40 ℃, then 1% of sodium bicarbonate is added, the rotary drum is continuously rotated for 1 h, and then liquid control is performed; adding 100% of water, 1% of A33 and 2% of RF-15 into a rotary drum, rotating at 35 ℃ for 1 h, adding 1% of DD42 and 1% of DD43, rotating for 1 h, adding 4% of TJ-R228 and 2% of leather palm S-EDK, rotating for 2 h, then adding a certain amount of formic acid, adjusting the pH of bath liquid to 4.0-4.2, rotating for 0.5 h, and controlling the liquid; 400% water is added into the rotary drum, the water is washed by 0.5 to h, and the liquid is controlled; adding 100% of water, 5% of HF and 5% of FS-95 into a rotary drum, dissolving the two materials by 50% of hot water, controlling the temperature to be 50 ℃, rotating 1 to h, adding a certain amount of formic acid, adjusting the pH of bath liquid to 3.6 to 3.8, rotating 0.5 to h, and controlling the liquid; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Comparative example 2 existing conventional tanning process

The sheep gray skin after the sheet skin is used as a raw material, 100 percent of water and 2 percent of organic phosphine salt tanning agent are added into a rotary drum according to the weight of the gray skin after the sheep gray skin is treated by a conventional softening process, sodium bicarbonate (10 times of hydration) is slowly added in steps after the rotary drum rotates for 4 h at normal temperature, the pH of bath liquid is regulated to 6.5, after the rotary drum rotates for 0.5 h, the temperature is raised to 40 ℃, the rotary drum continues to rotate for 4 h, and the rotary drum is stopped overnight; the next day, after 0.5 h is turned, 0.6 percent sodium perborate is added, after 1 h is turned at normal temperature, liquid is controlled, 400 percent water is added, after 0.5 h is washed, liquid is controlled, drum is taken out, and the leather is taken out of 24 h, thus obtaining tanned leather crust; the tanned leather is cut evenly, weighed, then added into a rotary drum, 400 percent of water and 0.5 percent of formic acid are added, and the rotary drum is rotated for 1 h at 40 ℃ and controlled; adding 100% of water, 1% of A33 and 2% of RF-15 into a rotary drum, rotating at 35 ℃ for 1 h, adding 1% of DD42 and 1% of DD43, rotating for 1 h, adding 4% of TJ-R228 and 2% of leather palm S-EDK, rotating for 2 h, then adding a certain amount of formic acid, adjusting the pH of bath liquid to 4.0-4.2, rotating for 0.5 h, and controlling the liquid; 400% water is added into the rotary drum, the water is washed by 0.5 to h, and the liquid is controlled; adding 100% of water, 5% of HF and 5% of FS-95 into a rotary drum, dissolving the two materials by 50% of hot water, controlling the temperature to be 50 ℃, rotating 1 to h, adding a certain amount of formic acid, adjusting the pH of bath liquid to 3.6 to 3.8, rotating 0.5 to h, and controlling the liquid; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Comparative example 3

Compared with example 1, the tanning agent is different, and the rest of the process conditions are the same as those of example 1, and the specific method is as follows:

the sheep gray skin after the sheet skin is used as a raw material, 50% of water and 4% of glutaraldehyde are added into a rotary drum according to the weight of the gray skin after the sheep gray skin is treated by a conventional softening process, the temperature is raised to 45 ℃, the pH of bath liquid is controlled to be 7.5, and the rotary drum is rotated by 2 h; adding 2% of A33 and 4% of RF-15 into a rotary drum, dissolving the two materials with 50% of water, adding the two materials, rotating for 1 h, adding 2% of DD42 and 2% of DD43, continuing rotating for 1 h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 5.5, and rotating for 0.5 h; adding 4% of TJ-R228, 1% of JLE and 4% of leather palm E5G, and rotating for 2 h; then adding 5% of HF and 5% of FS-95, dissolving the two materials with 50% of hot water, adding the two materials, controlling the temperature to be 50 ℃, rotating 1 to h, adding a certain amount of formic acid, adjusting the pH of the bath liquid to 3.6 to 3.8, rotating 0.5 to h, and controlling the liquid; adding 400% water, washing with water to 0.5. 0.5 h, controlling liquid, and drying to obtain crust leather.

Experimental example

Taking the processing of 1 ton pelt (calculated as ash weight) as an example, the length of time required from tanning to wet finishing is compared with the new water consumption, and the properties of crust leather under different processing systems are shown in table 1 and figure 1.

TABLE 1

。

As can be seen from table 1, the processing techniques provided in examples 1 and 4 significantly reduced the production time period (shortened from 3 days to 1 day in span) and the wastewater discharge compared to the processing techniques provided in comparative examples 1-2. Meanwhile, the crust leather produced by the processing technology provided by the embodiment has higher mechanical strength, equivalent softness, plumpness and excellent grain flatness fineness although the shrinkage temperature is slightly lower than that of chrome tannage crust leather. Although the production time period and the wastewater discharge amount were greatly reduced as compared with the processing technique provided in comparative example 3, each property of crust leather was poor except for the shrinkage temperature, and it was not commercially valuable. The results show that the technical scheme provided by the invention can be used for producing crust leather products with physical and organoleptic properties equivalent to those of conventional crust leather, and has commercial value.

The invention is based on the intensive study and the profound knowledge of the molecular structure and the performance of the synthetic aldehyde tanning agent and the bio-based aldehyde tanning agent by the applicant, and is innovated in leather manufacture. The aldehyde tanning agent used in the invention is a nonionic, anionic or amphoteric material, has good compatibility with common wet finishing materials, and can be used in the same bath, so that the gray leather or pickling leather can be converted into crust leather in a short time by adopting a one-pot method, besides the crust leather is washed, only one-time wastewater discharge is realized, and the water consumption of tanning and the wastewater discharge are greatly reduced. In comparison, other commonly used organic tanning agents (such as glutaraldehyde, organic phosphine salts and the like) and metal salt tanning agents have high reaction activity, poor permeability in the skin, and slightly improper tanning pH and temperature control can cause the problems of rough leather surface, non-penetration and the like. The waste liquid after tanning of the metal salt tanning agent contains a large amount of metal ions, and cannot be compatible with common wet finishing materials, so that wet finishing processing can be performed only after the working procedures of liquid exchange, water washing, rinsing, neutralization and the like are required. Therefore, only by using the aldehyde tanning agent and the process, the leather production efficiency can be effectively achieved, and the time cost and the wastewater discharge can be greatly saved. Meanwhile, the prepared crust leather has good wet heat stability, tensile strength, tearing strength, softness, fullness and grain fineness on the whole. The aldehyde tanning agent and the process are the whole technology, can synergistically improve the production efficiency of leather and the performance of crust leather, and cannot achieve the effect of the invention at present by using other tanning agents.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. A process for the production of leather based on aldehyde tanning agents, characterized in that it comprises the following steps:

taking gray skin or pickling skin as a raw material, adding an aldehyde tanning agent, finishing tanning at 35-45 ℃ and pH of bath liquid of 7.5-8.5, and adding dyeing and finishing materials in the same bath for wet finishing and drying to obtain crust leather;

the aldehyde tanning agent comprises any one or more of a synthetic aldehyde tanning agent and a biological aldehyde tanning agent;

the synthetic aldehyde tanning agent comprises TWT and/or TWS aldehyde tanning agent;

the bio-based aldehyde tanning agent comprises any one or more of dialdehyde starch, dialdehyde sodium alginate, dialdehyde sodium carboxymethyl cellulose, dialdehyde xanthan gum, dialdehyde cyclodextrin and dialdehyde methyl glucoside;

the specific method for wet finishing comprises the following steps: adding an acrylic resin retanning agent into the tanning bath, rotating for 1 h, adding an amino resin retanning agent, continuing rotating for 1 h, adjusting the pH of the bath to 5.5-6.5, and rotating for 0.5 h; adding vegetable tannin extract, synthetic tanning agent and dye, and rotating for 1-2 h; then adding a fatting agent, controlling the temperature to be 50 ℃, rotating for 1 h, adjusting the pH of the bath liquid to be 3.6-3.8, and rotating for 0.5 h; or (b)

Adding a fatliquor into tanning bath, controlling the temperature to be 50 ℃, rotating 1 h, controlling the bath temperature to be 35-45 ℃, then adding an acrylic resin retanning agent, rotating 1 h, adding an amino resin retanning agent, continuously rotating 1 h, adjusting the pH of the bath to be 5.5-6.5, and rotating 0.5 h; adding vegetable tannin extract, synthetic tanning agent and dye, and rotating for 1-2 h; then adjusting the pH of the bath liquid to 3.6-3.8, and rotating 0.5-h.

2. The leather production method based on the aldehyde tanning agent according to claim 1, wherein when the raw material is gray leather, 50% -80% of water and 2% -8% of the aldehyde tanning agent are added according to the weight of the gray leather for tanning, and after finishing one bath wet finishing, 200% -400% of water is added for washing, liquid control and drying;

3. The leather production method based on the aldehyde tanning agent according to claim 1, wherein after the aldehyde tanning agent is added, the leather is rotated for 0-2 h, the temperature is raised to 35-45 ℃, the pH of the bath liquid is controlled to be 7.5-8.5, and the leather is rotated for 2-4 h, so that the tanning is completed.

4. The method for producing leather based on aldehyde tanning agent according to claim 1, wherein when the raw material is ash skin, the total amount of the acrylic resin retanning agent, the amino resin retanning agent, the plant tanning agent and the synthetic tanning agent is 5% -15%, the dye amount is 2% -4% and the fatliquoring agent amount is 6% -15% based on the weight of the acid-soaked skin when the raw material is acid-soaked skin and based on the weight of 2 times of the acid-soaked skin.

5. The leather production method based on the aldehyde tanning agent according to claim 1, wherein a fixing agent is added into the bath after the wet finishing is finished, and after the bath is rotated for 1 to 2 hours, the crust leather is obtained after liquid control, water washing, liquid control again and drying;

the fixing agent is any one or more of aluminum sulfate octadecanoate and chromium-free complex tanning agents;

the addition amount of the fixing agent is 0.5% -2% based on the weight of ash skin or 2 times of pickled skin.