CN113462824B - Method for improving performance of organic chrome-free tanned leather - Google Patents

Abstract

The invention belongs to the technical field of leather processing, and discloses a method for improving the performance of organic chrome-free tanning. The invention can effectively improve the color fastness, shrinkage temperature and physical sensory property of finished leather by the organic synergy of the tanning agent, the dyeing and finishing material and the working procedure, and manufacture high-performance leather. The invention does not use the leather chemical material containing formaldehyde and chromium in the whole production process. Therefore, compared with the prior leather production technology based on the chrome tanning method, the invention can thoroughly eliminate the chromium pollution, has higher degree of cleanness and is more environment-friendly; meanwhile, compared with the existing leather production method based on the organic tanning technology, the leather prepared by the method does not contain formaldehyde and chromium, and has obviously better physical properties, thereby having higher market application value.

Description

Method for improving performance of organic chrome-free tanned leather

Technical Field

The invention relates to the technical field of leather processing, in particular to a method for improving the performance of organic chrome-free tanning.

Background

The production and manufacturing of leather mainly comprises a preparation section, a tanning section and a finishing section. Wherein, the preparation section mainly aims at removing leather-making useless objects and loosening collagen fibers to lay a foundation for tanning; the tanning section is the most critical, converts the hide which is not resistant to microorganisms and chemical reagents into the leather which is resistant to the action of heat, chemical reagents and microorganisms, and endows the leather blank with certain mechanical processing performances of chipping, grinding and the like; the finishing section has a crucial influence on the quality, properties and style of the final leather product. At present, the chrome tanning method is still the most main method for tanning leather, but the chromium-containing wastewater and solid waste pollution generated by the chrome tanning method severely restrict the sustainable development of the leather industry. Therefore, a chrome-free tanning technology must be vigorously developed to produce chrome-free leather. Based on life cycle evaluation (LCA), the organic tanning technology based on bio-based tanning agent is more advantageous in terms of environmental impact and resource consumption compared with non-chrome metal tanning technology, and is a more sustainable tanning technology. However, conventional dyeing and finishing materials have been developed mainly based on the properties of chrome tanned leather blanks, and their binding to bio-based tanning agent tanned leather blanks is not ideal, and it is difficult to impart an organic chromium-free leather product with excellent overall properties similar to chrome tanned leather products. Therefore, from the organic synergy angle of the tanning section and the finishing section, the development of the high-performance leather manufacturing technology based on the bio-based tanning agent has important significance for promoting the chrome-free leather industry, and is a direction with great social benefit and economic value.

The bio-based aldehyde tanning agent is an important bio-based tanning agent, and the tanning mechanism is an aldehyde tanning mechanism, namely active aldehyde groups on the bio-based aldehyde and amino groups on collagen undergo Schiff base reaction under the alkaline condition to form covalent bond combination, so that the multi-point cross-linked tanning effect is generated. As can be seen from the tanning mechanism described above, the tanning reaction consumes the amino groups on the collagen, lowering the isoelectric point of the tanned leather blanks (generally below 5.0). In the whole dyeing and finishing process, due to the low isoelectric point of the tanned leather blank, the tanned leather blank has the defects of insufficient absorption and combination on the conventional anionic dyeing and finishing material, and simultaneously, the tanned leather blank can be subjected to retanning under the conventional dyeing and finishing condition, so that the problems of unsatisfactory dyeing fastness, poor physical and sensory properties of finished leather and the like can be caused. In addition, in the high-temperature greasing process, the fixation of final greasing is carried out under the high-temperature acidic condition, and the Schiff base structure can carry out reversible reaction under the acidic condition, so that the leather blank can be tanned to a certain degree, the shrinkage temperature of the final leather blank is reduced, the dispersion and fixation of collagen fibers are influenced, and the physical sensory properties of the finished leather can be negatively influenced.

Disclosure of Invention

The invention aims to: aiming at the problems that the absorption and combination of dyeing and finishing materials are not ideal, the shrinkage temperature of crust leather is reduced, and the color fastness and physical organoleptic are not good inevitably generated in the production of bio-based aldehyde tanning based on the conventional dyeing and finishing technology, a method for improving the performance of organic chrome-free tanning is provided. The invention can effectively improve the color fastness, shrinkage temperature and physical sensory property of finished leather through the organic synergy of dyeing and finishing materials and working procedures, and manufacture organic chrome-free tanning leather products with more excellent performance. The invention does not use the leather chemical material containing formaldehyde and chromium in the whole production process. Therefore, compared with the prior leather production technology based on the chrome tanning method, the invention can thoroughly eliminate the chromium pollution, has higher degree of cleanness and is more environment-friendly; meanwhile, compared with the existing leather production method based on the organic tanning technology, the leather prepared by the method does not contain formaldehyde and chromium, and has obviously better physical properties, thereby having higher market application value.

In order to achieve the purpose, the invention provides the following technical scheme:

a method of improving organic chrome-free tanning performance, the method comprising the steps of:

the method comprises the following steps of (1) taking bio-based aldehyde tanned leather as a raw material, after being evenly shaved and rewetted, retanning the bio-based aldehyde tanned leather by adopting a conventional retanning agent and a bio-based amino resin retanning agent, and adding a functional dye to react after the retanning is finished; after the reaction is finished, discharging liquid, and adding a fatting agent for reaction; adding a fixing agent into the reacted system;

the method comprises the following steps of mixing a conventional retanning agent, a bio-based amino resin retanning agent, a functional dye and a fatliquor, wherein the conventional retanning agent is added in an amount of 3-10%, the bio-based amino resin retanning agent is added in an amount of 1-3%, the functional dye is added in an amount of 2-30%, and the fatliquor is added in an amount of 6-10% by weight of the shaved bio-based aldehyde tanned leather.

Further, the bio-based aldehyde tannages include, but are not limited to, any one or more of dialdehyde sodium alginate tannages, dialdehyde sodium carboxymethyl cellulose tannages, dialdehyde xanthan tannages, dialdehyde methyl glucoside tannages and dialdehyde glycosyl derivative tannages.

Further, the conventional retanning agent comprises any one or more of, but not limited to, acrylic resin retanning agents, tannin extract, protein filler and the like.

Further, the bio-based amino resin retanning agent is any one or more of bio-based dicyandiamide resin and bio-based melamine resin.

Further, the functional dye comprises any one or more of a small molecule amino-containing reactive dye and a high molecule dye.

Further, the polymer dye includes any one or more of an amino-terminated polymer dye and a carboxyl-type polymer dye.

Further, the fixing agent is any one or more of aluminum sulfate octadecahydrate and a chromium-free complex tanning agent; the adding amount of the fixing agent is 0.5-4% of the weight of the shaved bio-based aldehyde tanned leather.

Further, the specific method for adding the conventional retanning agent, the bio-based amino resin retanning agent, the functional dye and the fatliquor to react comprises the following steps: adding water into the rewetted shaved leather, keeping the temperature at 35 ℃, adding a conventional retanning agent, a bio-based amino resin retanning agent and a functional dye, and keeping the total rotation time at 2.5-3.5 hours;

adjusting the pH value of the mixed solution to 4.0-4.2, and discharging liquid after continuously rotating for 0.5 hour; and

and (3) adjusting the temperature of the reaction system to 50 ℃, adding a fat liquor which accounts for 6-10% of the weight of the uniformly shaved bio-based aldehyde tanned leather, rotating for 1.5 hours, adjusting the pH value of the bath liquid to 3.6-3.8, continuously rotating for 0.5 hour, and discharging liquid.

Further, the specific method for adding the fixing agent into the reacted system comprises the following steps:

adding normal-temperature water and a fixing agent into the reacted system, rotating for 1.0-4.0 hours, regulating the pH value of the mixed solution to 3.8-4.6 a little by many times, heating to 35-50 ℃ after rotating for 0.5 hours, and continuing to rotate for 1-3 hours.

The invention can control the performance and style of leather products (such as shoe upper leather, clothing leather and the like) by controlling the types and the use amounts of the retanning agent and the dye according to the types and the corresponding requirements of leather raw materials (such as sheepskin, cowhide and the like) and leather products (such as shoe upper leather, clothing leather and the like), and has the functions of improving softness, improving fullness, reducing position difference, improving dyeing fastness, improving mechanical strength and the like.

The invention aims at the problems of low dyeing fastness and unsatisfactory physical and sensory properties of finished leather in a bio-based aldehyde tanning production method based on a conventional dyeing and finishing technology, and improves a leather production process through organic synergy of materials and the process. In the case of bio-based aldehyde tanned leather, the isoelectric point is often low (generally lower than 5.0), which causes insufficient binding force between the leather blank and the conventional dyeing and finishing materials, and causes unsatisfactory physical properties of the leather product, such as thin and flat leather body, poor fullness, and the like. However, it is considered that various reactive groups such as aldehyde group, carboxyl group, hydroxyl group, etc. are contained in the molecular structure of the bio-based aldehyde tanning agent, and the combination with the dye with amino group, the plant tannin extract and the metal ion can be generated. Through carrying out the interconnection combination with above-mentioned multiple material, not only can strengthen anionic dyeing and finishing material at crust leather surface and inside fixed, still can avoid biology base aldehyde tanning agent to take place to show the tanning of withdrawing in dyeing and finishing process simultaneously, therefore the comprehensive properties of leather product can finally promote.

Particularly, functional dyes matched with the molecular structure of the bio-based aldehyde tanning agent are introduced in a targeted manner, and comprise small-molecule amino-containing reactive dyes, amino-terminated high-molecular dyes and carboxyl high-molecular dyes, and the fixing strength of the dyes in the leather is improved by utilizing the characteristic that the amino groups on the dye molecules and the residual reactive aldehyde groups on the bio-based aldehyde tanned leather can perform a cross-linking reaction and the characteristic that the filling effect of the high-molecular dye molecules in the leather is strong; when the carboxyl-type macromolecular dye is introduced, the strong filling property of the macromolecular chain of the carboxyl-type macromolecular dye is utilized, and the use of a fixing agent is further combined, so that the dye molecules, the bio-based aldehyde tanning agent and the collagen fibers are crosslinked, and the bonding strength of the dye in leather is improved. In view of the above, the present invention provides a method for improving the performance of organic chrome-free tanning.

The leather product produced by adopting the technical scheme of the invention has the shrinkage temperature of 80-90 ℃, the overall physical sensory property close to the level of the conventional chrome tanned leather, and the mechanical strength is even higher. In addition, because the tanning property of the bio-based aldehyde tanning agent is mild, the bio-based aldehyde tanning agent has weak astringency on the leather surface, and the produced leather product has the characteristic of flat and fine grain surface. Importantly, the leather product does not contain free formaldehyde and chromium, completely meets the requirements of ecological leather, and is suitable for the production of leather products such as clothes, inclined planes, sofas, automobile cushions, bags and the like.

In summary, the technical scheme provided by the invention has the following advantages:

1) based on the deep knowledge of the molecular structure characteristics of the used bio-based aldehyde tanning agent and the charge property of the tanned leather blank, the invention uses functional dyes in a targeted manner, wherein the functional dyes comprise micromolecule amino-containing reactive dyes, amino-terminated high molecular dyes and carboxyl-containing high molecular dyes, so that the functional dyes have stronger bonding force with the leather blank and provide stronger covering power simultaneously, thereby improving the dyeing fastness and the uniformity; in addition, when the high molecular dye is used, the using amount of the conventional retanning agent can be reduced, so that the effect of killing two birds with one stone is achieved;

2) according to the invention, a small amount of fixing agent is used for fixing the dyeing and finishing material, so that the dyeing and finishing material can be efficiently combined in the bio-based aldehyde tanned leather, the dyeing fastness is improved, the phenomenon that the bio-based aldehyde tanned agent is subjected to retanning in the dyeing and finishing process is avoided, the shrinkage temperature of the final crust leather is improved, the final crust leather can reach 80-90 ℃, and the guarantee is provided for the leather to have good fullness;

3) the tanning leather blank is obtained by tanning with bio-based aldehyde as a tanning agent, the tanning agent is prepared by using renewable glycosyl biomass as a raw material, and has excellent sustainability, and the selected bio-based aldehyde tanning agent does not contain formaldehyde, so the tanning leather blank has good ecological environmental protection property, and the tanning leather blank can be used for manufacturing ecological leather by virtue of retorting of dyeing and finishing materials;

4) the bio-based amino resin used by the invention is synthesized by using the bio-based aldehyde without formaldehyde as a raw material, does not contain formaldehyde, has excellent permeability in tanning leather blanks by using the bio-based aldehyde tanning agent, has certain binding force with retanning agents such as tannin extract and the like, can strengthen the fixation of other retanning agents in leather, and plays a good filling role;

5) the invention does not introduce any chrome-containing tanning agent or chrome-containing retanning agent in the whole wet operation procedure, does not generate chrome-containing wastewater and chrome-containing solid waste at all, has high degree of cleanness, and can help tanning industry to realize chrome-free.

Detailed Description

The present invention is described in detail below with reference to specific embodiments, it should be noted that the embodiments are only used for further illustration of the present invention, and should not be construed as limiting the scope of the present invention, and those skilled in the art can make modifications and adaptations of the present invention based on the above-mentioned disclosure.

It is also worth mentioning that 1) the shrinkage temperature of the crust leather is measured using a shrinkage thermometer; 2) the mechanical strength of the crust leather is measured by a high-speed rail servo control tension tester; 3) the softness of crust leather is measured by a softness instrument; 4) the dyeing performance is graded by measuring the dry and wet rubbing resistance and the dyeing uniformity of the crust leather, the highest grade is 5, and the higher the score is, the better the dyeing performance is represented; 5) the plumpness of the crust leather is measured by a compression-rebound performance method, and then the excellent medium-poor leather is used for grading.

The dyeing and finishing materials used in the examples and comparative examples are all exemplified materials, and are not intended to limit the present invention, and the specific information is as follows: the acrylic resin retanning agents (A33, RF 15) and the fatting agents (HF, FS-95) are leather chemical materials produced by Sichuan Dawei science and technology Limited; commercial pickling-free chrome-free tanning agent (TWT), wattle bark tannin extract (TJ-R228), tara tannin extract (TJ-R231), protein filler (TJ-950), chrome tanning agent (TJ-T125) and chrome-free complex tanning agent (TWLZ) are leather chemical materials produced by Szechwan river new materials GmbH; the bio-based melamine resin is prepared by reacting bio-based aldehyde and melamine, the product is powder, the bio-based dicyandiamide resin is prepared by reacting bio-based aldehyde and dicyandiamide, and the product is powder, and the two types of bio-based amino resins have similar medium and high molecular weight and molecular structure characteristics, so that the two types of bio-based amino resins can be used for the invention to achieve the same effect; the amino-terminated polymer dye and the carboxyl-type polymer dye used in the examples are only polymer dyes synthesized based on aqueous polyurethane and polyacrylic acid polymers, and all of the amino-terminated polymer dye and the carboxyl-type polymer dye can be used in the present invention to achieve the same effect because both of the amino-terminated polymer dye and the carboxyl-type polymer dye have a macromolecule chain and have commonness with amino groups or carboxyl groups.

Example 1

This example illustrates the general steps of a method for producing high-performance leather, which specifically comprises:

after the bio-based aldehyde tanned leather is evenly shaved and rewetted, adding a conventional retanning agent, a bio-based amino resin retanning agent, a functional dye and a fatliquor for reaction; the method specifically comprises the following steps: squeezing water and shaving the bio-based aldehyde tanned leather to obtain shaved leather, and weighing the shaved leather as a material reference of a subsequent material; firstly, rewetting according to a conventional process, then putting the rewetted leather into a rotary drum, adding 100% of water by weight of the shaved leather, keeping the temperature in the drum at 35 ℃, adding 3-10% of conventional retanning agent by weight of the shaved leather, 1-3% of bio-based amino resin retanning agent and 2-30% of functional dye into the rotary drum step by step, wherein the total rotating time is 2.5-3.5 hours, then adding 1.0-1.5% of formic acid by weight of the shaved leather into the rotary drum, adding the formic acid by step, adjusting the pH value of bath liquid to 4.0-4.2, then continuing to rotate for 0.5 hours, and discharging liquid; and adding hot water accounting for 150% of the weight of the shaved leather into the rotary drum, keeping the temperature in the drum at 50 ℃, adding a fatting agent accounting for 6% -10% of the weight of the shaved leather, rotating for 1.5 hours, adding formic acid accounting for 1.0% -1.5% of the weight of the shaved leather, adjusting the pH value of the bath liquid to 3.6-3.8, continuously rotating for 0.5 hour, and discharging the liquid.

Adding a fixing agent into the reacted system; the method specifically comprises the following steps: and continuously adding normal-temperature water accounting for 100% of the weight of the shaved leather and 0.5-4% of a fixing agent into the rotary drum, rotating for 1.0-4.0 hours, then adding a small amount of alkali liquor for multiple times to adjust the pH value of the bath liquid to 3.8-4.6, heating to 35-50 ℃ after rotating for 0.5 hour, continuously rotating for 1-3 hours, washing with water, discharging to obtain chrome-free crust leather, and drying and finishing to obtain the high-performance leather.

The bio-based aldehyde tannage comprises any one or more of dialdehyde glycosyl derivative tannages such as dialdehyde sodium alginate tannage, dialdehyde sodium carboxymethyl cellulose tannage, dialdehyde xanthan gum tannage and dialdehyde methyl glucoside tannage; the conventional retanning agent comprises any one or more of, but is not limited to, acrylic resin retanning agent, tannin extract, protein filler and the like; the bio-based amino resin retanning agent is any one or more of bio-based dicyandiamide resin and bio-based melamine resin.

The functional dye comprises any one or more of small molecule amino-containing reactive dye and high molecule dye; the macromolecular dye comprises any one or more of amino-terminated macromolecular dye and carboxyl-type macromolecular dye; the fixing agent is any one or more of aluminum sulfate octadecahydrate and a chromium-free complex tanning agent; the adding amount of the fixing agent is 0.5-4% of the weight of the shaved bio-based aldehyde tanned leather.

Examples 2 to 9: for illustrating the specific manufacturing process of high performance leather:

example 2

A method for improving the performance of organic chrome-free tanning comprises the following steps:

(1) squeezing and shaving the dialdehyde methyl glucoside tanned leather to obtain shaved leather, and weighing the shaved leather as a material reference of a subsequent material; firstly, rewetting according to a conventional process, then putting the rewetted leather into a rotary drum, adding 100% of water by weight of the shaved leather, keeping the temperature in the drum at 35 ℃, adding 1% of macromolecular acrylic resin retanning agent A33, 2% of medium and small molecular acrylic resin retanning agent RF15, 3% of protein filler TJ-950, 1% of dialdehyde sodium alginate-melamine resin retanning agent, 4% of wattle bark tannin extract TJ-R228 and 2% of active red 180 into the rotary drum step by step, wherein the total rotation time is 2.5 hours, then adding 1.0-1.5% of formic acid by weight of the shaved leather into the rotary drum, adding the formic acid by step, adjusting the pH value of a bath solution to 4.0-4.2, continuing to rotate for 0.5 hours, and discharging liquid; adding hot water accounting for 150% of the weight of the shaved leather into the rotary drum, keeping the temperature in the drum at 50 ℃, adding a fatting agent HF accounting for 4% of the weight of the shaved leather and a fatting agent FS-95 accounting for 4%, rotating for 1.5 hours, adding formic acid accounting for 1.0-1.5% of the weight of the shaved leather, adjusting the pH value of bath liquid to 3.6-3.8, continuously rotating for 0.5 hours, and discharging liquid;

(2) and continuously adding normal-temperature water with the weight of 100 percent of the even leather and aluminum sulfate octadecahydrate with the weight of 2.5 percent of the even leather into the rotary drum, rotating for 2.0 hours, then adding a small amount of alkali liquor for multiple times to adjust the pH value of the bath solution to 4.2, rotating for 0.5 hour, heating to 40 ℃, continuously rotating for 3 hours, washing, discharging from the drum to obtain chromium-free crust leather, and drying and finishing to obtain the high-performance leather.

Example 3

A method for improving the performance of organic chrome-free tanning comprises the following steps:

(1) squeezing and shaving the dialdehyde sodium alginate tanned leather to obtain shaved leather, and weighing the shaved leather as a material reference of a subsequent material; firstly, rewetting according to a conventional process, then putting the rewetted leather into a rotary drum, adding 100% of water by weight of the shaved leather, keeping the temperature in the drum at 35 ℃, adding 1% of macromolecular acrylic resin retanning agent A33 by weight of the shaved leather, 0.5% of medium and small molecular acrylic resin retanning agent RF15, 1% of dialdehyde methyl glucoside-dicyandiamide resin retanning agent, 1% of dialdehyde sodium carboxymethyl cellulose-melamine resin retanning agent, 2% of wattle bark tannin extract TJ-R228, 1% of tara tannin extract TJ-R231, and 15% of amino-terminated aqueous polyurethane red dye synthesized by taking IPDI, PEG-400 and acid red 14 as main raw materials into the rotary drum step by step, adding formic acid with 1.0% -1.5% by weight of the shaved leather into the rotary drum for 3.0 hours in a plurality of times, adjusting the pH of bath liquid to 4.0-4.2, continuing to rotate for 0.5 hours, draining; adding hot water accounting for 150% of the weight of the shaved leather into the rotary drum, keeping the temperature in the drum at 50 ℃, adding a fatting agent HF accounting for 4% of the weight of the shaved leather and a fatting agent FS-95 accounting for 4%, rotating for 1.5 hours, adding formic acid accounting for 1.0-1.5% of the weight of the shaved leather, adjusting the pH value of bath liquid to 3.6-3.8, continuously rotating for 0.5 hours, and discharging liquid;

(2) and continuously adding normal-temperature water with the weight of the even leather being 100% and aluminum sulfate octadecahydrate with the weight of 3.5% into the rotary drum, rotating for 4.0 hours, then adding a small amount of alkali liquor for multiple times to adjust the pH value of the bath solution to 3.8, rotating for 0.5 hours, heating to 45 ℃, continuously rotating for 2 hours, washing with water, discharging out of the drum to obtain chromium-free crust leather, and drying and finishing to obtain the high-performance leather.

Example 4

A method for improving the performance of organic chrome-free tanning comprises the following steps:

(1) squeezing and shaving the dialdehyde sodium carboxymethyl cellulose tanned leather to obtain shaved leather, and weighing the shaved leather as a material reference of a subsequent material; firstly, rewetting according to a conventional process, then putting the rewetted leather into a rotary drum, adding 100% of water by weight of the shaved leather, keeping the temperature in the drum at 35 ℃, adding 0.5% of macromolecular acrylic resin retanning agent A33, 0.5% of medium and small molecular acrylic resin retanning agent RF15, 1% of protein filler TJ-950, 1% of dialdehyde sodium alginate-dicyandiamide resin retanning agent, 2% of dialdehyde methyl glucoside-melamine resin retanning agent, 1% of bark tannin extract TJ-R228, 30% of amino-terminated aqueous polyurethane red dye synthesized by taking IPDI, PPG-1000 and disperse red 91 as main raw materials into the rotary drum, wherein the total rotation time is 3.5 hours, then adding 1.0% -1.5% of formic acid by weight of the shaved leather into the rotary drum, adding the tanning agent in portions, adjusting the pH bath liquid to 4.0-4.2, continuing to rotate for 0.5 hours, draining; adding hot water accounting for 150% of the weight of the shaved leather into the rotary drum, keeping the temperature in the drum at 50 ℃, adding a fatting agent HF accounting for 3% of the weight of the shaved leather and a fatting agent FS-95 accounting for 3%, rotating for 1.5 hours, adding formic acid accounting for 1.0% -1.5% of the weight of the shaved leather, adjusting the pH value of bath liquid to 3.6-3.8, continuously rotating for 0.5 hours, and discharging liquid;

(2) and continuously adding normal-temperature water accounting for 100 percent of the weight of the even leather and a chrome-free complex tanning agent TWLZ accounting for 0.5 percent of the weight of the even leather into the rotary drum, rotating for 1.0 hour, adding a small amount of alkali liquor for multiple times to adjust the pH value of the bath solution to 4.0, rotating for 0.5 hour, raising the temperature to 35 ℃, continuously rotating for 1 hour, washing with water, discharging out of the drum to obtain chrome-free crust leather, and drying and finishing to obtain the high-performance leather.

Example 5

(1) Squeezing and shaving leather tanned by dialdehyde xanthan gum to obtain shaved leather, and weighing the shaved leather as a material reference of a subsequent material; firstly, rewetting according to a conventional process, then putting the rewetted and shaved leather into a rotary drum, adding 100% of water by weight of the shaved leather, keeping the temperature in the drum at 35 ℃, adding 2% of macromolecular acrylic resin retanning agent A33, 3% of dialdehyde xanthan gum-dicyandiamide resin retanning agent, 4% of tara tannin extract TJ-R231 and 10% of amino-terminated aqueous polyurethane red dye synthesized by taking IPDI, PTMG-1000 and disperse red 11 as main raw materials into the rotary drum step by step, wherein the total rotation time is 3.0 hours, then adding 1.0-1.5% of formic acid by weight of the shaved leather into the rotary drum, adding the formic acid in steps, adjusting the pH value of a bath solution to 4.0-4.2, continuing to rotate for 0.5 hours, and discharging liquid; adding hot water accounting for 150% of the weight of the shaved leather into the rotary drum, keeping the temperature in the drum at 50 ℃, adding a fat liquor HF accounting for 5% of the weight of the shaved leather and a fat liquor FS-95 accounting for 5% of the weight of the shaved leather, rotating for 1.5 hours, adding formic acid accounting for 1.0-1.5% of the weight of the shaved leather, adjusting the pH value of bath liquid to 3.6-3.8, continuously rotating for 0.5 hours, and discharging liquid;

(2) and continuously adding normal-temperature water with the weight of 100 percent of the even leather, aluminum sulfate octadecahydrate with the weight of 1.5 percent and the chrome-free complex tanning agent TWLZ with the weight of 1.0 percent into the rotary drum, rotating for 4.0 hours, then adding a small amount of alkali liquor for multiple times to adjust the pH value of the bath solution to 4.6, heating to 50 ℃ after rotating for 0.5 hour, continuously rotating for 2 hours, washing with water, discharging to obtain chrome-free crust leather, and drying and finishing to obtain the high-performance leather.

Example 6

A method for improving the performance of organic chrome-free tanning comprises the following steps:

(1) squeezing and shaving the dialdehyde methyl glucoside tanned leather to obtain shaved leather, and weighing the shaved leather as a material reference of a subsequent material; firstly, rewetting according to a conventional process, then putting the rewetted leather into a rotary drum, adding 100% of water by weight of the shaved leather, keeping the temperature in the drum at 35 ℃, adding 0.8% of macromolecular acrylic resin retanning agent A33, 0.5% of medium and small molecular acrylic resin retanning agent RF15, 1% of dialdehyde methyl glucoside-dicyandiamide resin retanning agent, 1% of dialdehyde sodium alginate-melamine resin retanning agent, 2% of wattle bark tannin extract TJ-R228, 1% of tara tannin extract TJ-R231, 1% of reactive blue K-GR and 5% of amino-terminated aqueous polyurethane blue dye synthesized by taking TDI, PPG-1000 and disperse blue 14 as main raw materials into the rotary drum step by step, wherein the total rotation time is 3.0 hours, then adding 1.0-1.5% of formic acid by weight of the shaved leather into the rotary drum, adding the bath foam into the rotary drum step by step, adjusting the pH value to 4.0-4.2, then continuously rotating for 0.5 hour to discharge liquid; adding hot water accounting for 150% of the weight of the shaved leather into the rotary drum, keeping the temperature in the drum at 50 ℃, adding a fatting agent HF accounting for 3% of the weight of the shaved leather and a fatting agent FS-95 accounting for 3%, rotating for 1.5 hours, adding formic acid accounting for 1.0% -1.5% of the weight of the shaved leather, adjusting the pH value of bath liquid to 3.6-3.8, continuously rotating for 0.5 hours, and discharging liquid;

(2) and continuously adding normal-temperature water with the weight of 100 percent of the even leather, 2.5 percent of aluminum sulfate octadecahydrate and 0.5 percent of chromium-free complex tanning agent TWLZ into the rotary drum, rotating for 4.0 hours, then adding a small amount of alkali liquor for multiple times to adjust the pH value of the bath solution to 3.8, heating to 45 ℃ after rotating for 0.5 hour, continuously rotating for 2 hours, washing with water, discharging to obtain chromium-free crust leather, and drying and finishing to obtain the high-performance leather.

Example 7

A method for improving the performance of organic chrome-free tanning comprises the following steps:

(1) squeezing and shaving leather by combining dialdehyde sodium alginate and dialdehyde methyl glucoside with tanned leather to obtain shaved leather, and weighing the shaved leather as a reference of the subsequent materials; firstly, rewetting according to a conventional process, then putting the rewetted leather into a rotary drum, adding water with the weight of 100% of the shaved leather, keeping the temperature in the drum at 35 ℃, adding a macromolecular acrylic resin retanning agent A33 with the weight of 0.5% of the shaved leather, a medium and small molecular acrylic resin retanning agent RF15 with the weight of 0.5% of the shaved leather, a dialdehyde methyl glucoside-melamine resin retanning agent with the weight of 3%, a wattle bark tannin extract TJ-R228 with the weight of 1%, a tara tannin extract TJ-R231 with the weight of 1% and a polyacrylic acid-acrylamide type macromolecular dye with the weight of 20% step by step into the rotary drum, wherein the total rotation time is 3.5 hours, then adding formic acid with the weight of 1.0-1.5% of the shaved leather into the rotary drum, adding the formic acid by step, adjusting the pH of a bath solution to 4.0-4.2, continuing to rotate for 0.5 hours, and discharging the liquid; adding hot water accounting for 150% of the weight of the shaved leather into the rotary drum, keeping the temperature in the drum at 50 ℃, adding a fat liquor HF accounting for 5% of the weight of the shaved leather and a fat liquor FS-95 accounting for 5% of the weight of the shaved leather, rotating for 1.5 hours, adding formic acid accounting for 1.0-1.5% of the weight of the shaved leather, adjusting the pH value of bath liquid to 3.6-3.8, continuously rotating for 0.5 hours, and discharging liquid;

(2) and continuously adding normal temperature water accounting for 100 percent of the weight of the even-shaved leather and a chromium-free complex tanning agent TWLZ accounting for 1.5 percent of the weight of the even-shaved leather into the rotary drum, rotating for 3.0 hours, adding a small amount of alkali liquor for multiple times to adjust the pH value of the bath solution to 4.0, rotating for 0.5 hour, heating to 40 ℃, continuously rotating for 3 hours, washing with water, discharging out of the drum to obtain chromium-free crust leather, and drying and finishing to obtain the high-performance leather.

Example 8

A method for improving the performance of organic chrome-free tanning comprises the following steps:

(1) the dialdehyde sodium carboxymethyl cellulose and the dialdehyde methyl glucoside are combined with tanned leather to be flushed and shaved evenly to obtain shaved leather, and the shaved leather is weighed to be used as the reference of the subsequent materials; firstly, rewetting according to a conventional process, then putting the rewetted leather into a rotary drum, adding 100% of water by weight of the shaved leather, keeping the temperature in the drum at 35 ℃, adding 3% of macromolecular acrylic resin retanning agent A33 by weight of the shaved leather, 1% of protein filler TJ-950, 0.5% of dialdehyde sodium alginate-dicyandiamide resin retanning agent, 0.5% of dialdehyde sodium alginate-melamine resin retanning agent, 4% of wattle bark tannin extract TJ-R228 and 2% of active brilliant blue K-GR into the rotary drum step by step, wherein the total rotation time is 2.5 hours, then adding 1.0-1.5% of formic acid by weight of the shaved leather into the rotary drum, adding the formic acid by step, adjusting the pH value of a bath liquid to 4.0-4.2, continuing to rotate for 0.5 hours, and discharging the liquid; adding hot water accounting for 150% of the weight of the shaved leather into the rotary drum, keeping the temperature in the drum at 50 ℃, adding a fatting agent HF accounting for 4% of the weight of the shaved leather and a fatting agent FS-95 accounting for 4%, rotating for 1.5 hours, adding formic acid accounting for 1.0-1.5% of the weight of the shaved leather, adjusting the pH value of bath liquid to 3.6-3.8, continuously rotating for 0.5 hours, and discharging liquid;

(2) and continuously adding normal-temperature water with the weight of the even leather being 100% and aluminum sulfate octadecahydrate with the weight of 2.5% into the rotary drum, rotating for 1.0 hour, then adding a small amount of alkali liquor for multiple times to adjust the pH value of the bath liquid to 3.8, rotating for 0.5 hour, heating to 50 ℃, continuously rotating for 2 hours, washing with water, discharging out of the drum to obtain chromium-free crust leather, and drying and finishing to obtain the high-performance leather.

Example 9

A method for improving the performance of organic chrome-free tanning comprises the following steps:

(1) squeezing and shaving the dialdehyde methyl glucoside tanned leather to obtain shaved leather, and weighing the shaved leather as a material reference of a subsequent material; firstly, rewetting according to a conventional process, then putting the rewetted leather into a rotary drum, adding 100% of water by weight of the shaved leather, keeping the temperature in the drum at 35 ℃, adding 0.5% of macromolecular acrylic resin retanning agent A33, 0.5% of medium and small molecular acrylic resin retanning agent RF15, 1.5% of dialdehyde sodium alginate-dicyandiamide resin retanning agent, 1.5% of dialdehyde xanthan gum-melamine resin retanning agent, 3.5% of wattle extract TJ-R228, 1% of active red 180, 5% of amino-terminated aqueous polyurethane red dye synthesized by taking IPDI, PEG-400 and disperse red 91 as main raw materials into the rotary drum step by step, adding formic acid with the weight of 1.0% -1.5% of the shaved leather into the rotary drum, adding the formic acid in step by step, adjusting the pH bath liquid to 4.0-4.2, continuing to rotate for 0.5 hours, and discharging liquid; adding hot water accounting for 150% of the weight of the shaved leather into the rotary drum, keeping the temperature in the drum at 50 ℃, adding a fatting agent HF accounting for 3% of the weight of the shaved leather and a fatting agent FS-95 accounting for 3%, rotating for 1.5 hours, adding formic acid accounting for 1.0% -1.5% of the weight of the shaved leather, adjusting the pH value of bath liquid to 3.6-3.8, continuously rotating for 0.5 hours, and discharging liquid;

(2) and continuously adding normal-temperature water accounting for 100 percent of the weight of the shaved leather and a chromium-free complex tanning agent TWLZ accounting for 1.0 percent of the weight of the shaved leather into the rotary drum, rotating for 2.0 hours, adding a small amount of alkali liquor for multiple times to adjust the pH value of the bath solution to 4.2, rotating for 0.5 hour, heating to 40 ℃, continuously rotating for 2 hours, washing, discharging to obtain chromium-free crust leather, and drying and finishing to obtain the high-performance leather.

It can be seen from the above examples 3-7 and 9 that the amount of conventional retanning agent when using high molecular dyes is significantly lower than in examples 2 and 8.

Example 10

This example illustrates the effect of the use and process of a representative bio-based aldehyde tanning, dye and fixative on the properties of the leather produced, the composition and process of the added acrylic resin retanning agent, bio-based amino resin retanning agent, tannin extract are the same as in example 2, and the specific composition, process and properties are shown in table 1, with only the amounts and processes of the bio-based aldehyde tanning agent, dye and fixative being changed.

TABLE 1

。

Comparative example

This comparative example is used to illustrate the effect of the use of representative dyes and fixatives and their matching process on the performance of non-bio-based aldehyde tannages, the ingredients and processes of adding the acrylic resin retanning agent, bio-based amino resin retanning agent, tannin extract are the same as in example 2, only the type of functional dyes and the type of tanned leather blanks are changed, and the specific ingredients, amounts, processes and performance are shown in table 2.

TABLE 2

。

As can be seen from table 1, the crust leathers provided by samples 1-4 have overall higher tensile strength, tear strength, softness, dyeability, fullness and shrinkage temperature under the key fixing process conditions of the present invention. The crust leathers of the comparative samples 1-3 have lower tensile strength, tearing strength, softness, dyeing property, fullness and shrinkage temperature on the whole besides the key fixed process condition parameters. As can be seen from table 2, when other tanned leather blanks are used as objects for dyeing and finishing, the dyeing and finishing technical scheme provided by the invention cannot endow the leather blanks with high tensile strength, tearing strength, softness and dyeing performance. Besides the excellent sensory properties of chrome tanned crust leather, the sensory properties of TWLZ and TWTZ tanned crust leather are lower.

Therefore, only by simultaneously using the protective bio-based aldehyde tanning, the dye and the fixing agent which are required by the invention and according to the process required by the invention, the prepared crust leather has higher tensile strength, tearing strength, softness, dyeing property, fullness and shrinkage temperature on the whole; the bio-based aldehyde tanning agent, the dye and the fixing agent, and the using amount and the process thereof are a technical whole, the performance of crust leather can be synergistically improved, and the effect of the bio-based aldehyde tanning agent cannot be achieved after any parameter (such as a comparison sample 1-3) is changed. This is mainly because: (1) the bio-based aldehyde tanning agent used in the invention has a plurality of active groups and can be combined with plant tannin extract and the like; (2) the functional dye used in the invention can be combined with a bio-based aldehyde tanning agent and a bio-based amino resin fixed in the leather blank besides being combined with the leather collagen fiber, thereby greatly improving the combining fastness of the functional dye and the leather blank; (3) in the last step, a small amount of fixing agent, namely tanning metal ions, is introduced, and the dyeing and finishing material absorbed and fixed by the leather blank at the early stage is fixed based on the coordination reaction principle, so that the bonding fastness of the dyeing and finishing material in the interior and on the surface of the leather blank is further remarkably improved; (4) besides the key fixing process condition parameters, the method can not ensure that the fixation can play a good cross-linking fixing role, and the excessive temperature and pH can cause the binding force of the dye and the leather blank to be reduced and released, thereby causing the reduction of the dyeing performance; (5) both chrome tanned leather and TWLZ tanned leather have higher isoelectric points, and in this case, when a high molecular dye is introduced into a dyeing and finishing system, the high molecular dye can be excessively combined on the surface of a leather blank, so that the permeation of other dye materials into the leather is influenced, and finally, the physical and sensory properties of the leather blank are negatively influenced to a certain degree; when the small-molecule amino-containing reactive dye is introduced into a dyeing and finishing system, the small-molecule amino-containing reactive dye cannot be well combined with a leather blank under the fixing process condition of a dyeing and finishing material, so that the dyeing performance is not ideal. In conclusion, the invention realizes the reinforcement of the collagen fiber network structure in the leather blank through the organic cooperation of various functional materials and processing technologies, so that the final leather blank shows excellent physical sensory properties macroscopically.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (6)

1. A method for improving the performance of organic chrome-free tanned leather, comprising the steps of:

the method comprises the following steps of (1) taking bio-based aldehyde tanned leather as a raw material, after being evenly shaved and rewetted, retanning the bio-based aldehyde tanned leather by adopting a conventional retanning agent and a bio-based amino resin retanning agent, and adding a functional dye to react after the retanning is finished; after the reaction is finished, discharging liquid, and adding a fatting agent for reaction; adding a fixing agent into the reacted system;

the method comprises the following steps of (1) grinding a bio-based aldehyde tanned leather, wherein the weight of a conventional retanning agent is 3% -10%, the adding amount of a bio-based amino resin retanning agent is 1% -3%, the adding amount of a functional dye is 2% -30%, and the adding amount of a fatliquor is 6% -10%;

the bio-based amino resin retanning agent is any one or more of bio-based dicyandiamide resin and bio-based melamine resin;

the functional dye comprises any one or more of small molecule amino-containing reactive dye and high molecule dye;

the macromolecular dye comprises any one or more of amino-terminated macromolecular dye and carboxyl-type macromolecular dye.

2. The method of claim 1, wherein the biobased aldehyde tannages comprise, but are not limited to, any one or more of dialdehyde sodium alginate tannage, dialdehyde sodium carboxymethyl cellulose tannage, dialdehyde xanthan tannage, dialdehyde methyl glucoside tannage.

3. A method according to claim 1 wherein the conventional retanning agent includes, but is not limited to, any one or more of an acrylic resin retanning agent, a tannin extract, a protein filler.

4. The method of claim 1, wherein the fixing agent is any one or more of aluminum sulfate octadecahydrate, a chrome-free complex tanning agent; the adding amount of the fixing agent is 0.5-4% of the weight of the shaved bio-based aldehyde tanned leather.

5. The method of claim 1, wherein adding a conventional retanning agent, a bio-based amino resin retanning agent, a functional dye, and a fatliquor agent comprises: adding water into the rewetted shaved leather, keeping the temperature at 35 ℃, adding a conventional retanning agent, a bio-based amino resin retanning agent and a functional dye, and keeping the total rotation time at 2.5-3.5 hours;

adjusting the pH value of the mixed solution to 4.0-4.2, and discharging liquid after continuously rotating for 0.5 hour; and

and (3) adjusting the temperature of the reaction system to 50 ℃, adding a fat liquor which accounts for 6-10% of the weight of the uniformly shaved bio-based aldehyde tanned leather, rotating for 1.5 hours, adjusting the pH value of the bath liquid to 3.6-3.8, continuously rotating for 0.5 hour, and discharging liquid.

6. The method of claim 1, wherein the step of adding a fixative to the reacted system comprises:

adding normal-temperature water and a fixing agent into the reacted system, rotating for 1.0-4.0 hours, regulating the pH value of the mixed solution to 3.8-4.6 a little by many times, heating to 35-50 ℃ after rotating for 0.5 hours, and continuing to rotate for 1-3 hours.