阅读说明：本技术 可用于无水鞣制中的预处理的组合物及相应的鞣制方法 (Composition useful for pretreatment in waterless tanning and corresponding tanning process ) 是由 P·塔尼凯维兰 R·阿拉韦德汗 B·马丹 P·萨拉瓦南 J·R·拉奥 于 2018-05-30 设计创作，主要内容包括：铬或植物鞣制期间水的使用是不可避免的,因为其对于鞣剂在基质中的扩散和分布很重要。这导致产生了需要进行有效管理的含有污染物如铬的废水。本发明涉及用于更有效且容易地实施无水鞣制的新型组合物。所述组合物的制备涉及无水鞣制期间预处理所需的关键专用化学品的审慎组合。用于无水鞣制中的预处理的新型组合物的使用使得能够降低需水量、工艺持续时间以及成本。此外,还避免了使用盐和碱化过程。本发明致力于在皮革工业中实现可持续性。(The use of water during chrome or vegetable tanning is unavoidable because it is important for the diffusion and distribution of the tanning agent in the matrix. This results in wastewater containing contaminants such as chromium that need to be effectively managed. The present invention relates to a novel composition for more effectively and easily performing waterless tanning. The preparation of the composition involves a judicious combination of key specialty chemicals required for pretreatment during dry tanning. The use of the novel composition for pretreatment in waterless tanning enables reduction of water demand, process duration and cost. In addition, the use of salt and alkalization processes is avoided. The present invention is directed to achieving sustainability in the leather industry.)

1. A composition useful for pretreatment in waterless tanning, wherein the composition comprises:

a)90 to 95% (v/v) of an organic acid having a carbon chain length in the range of C1 to C3 with a transparent appearance;

b)3 to 8% (v/v) primary alcohols having a carbon chain length in the range of C1 to C3; and

c)2 to 5% (v/v) of a nonionic surfactant.

2. The composition as claimed in claim 1, wherein the organic acids used are selected from formic acid, acetic acid, propionic acid, individually or in different combinations.

3. A composition as claimed in claim 1, wherein the primary alcohols used are selected from methanol, ethanol, propan-2-ol, alone or in different combinations.

4. A composition as claimed in claim 1 wherein the non-ionic surfactant used is selected from 2- [4- (2,4, 4-trimethylpent-2-yl) phenoxy ] ethanol, polyoxyethylene (20) sorbitan monooleate, [2- [ (2R,3S,4R) -3, 4-dihydroxytetrahydrofuran-2-yl ] -2-hydroxyethyl ] stearate, alone or in different combinations.

5. A process for preparing a composition as claimed in claim 1, wherein the step comprises mixing 90 to 95% (v/v) of an organic acid having a carbon chain length in the range of C1 to C3, 3 to 8% (v/v) of a primary alcohol having a carbon chain length in the range of C1 to C3, and 2 to 5% (v/v) of a nonionic surfactant for a period of time in the range of 5 to 30 minutes to obtain the desired composition, wherein the composition is water soluble, exhibits a pH in the range of 1.8 to 2.6 as a 10% solution, and is characterized by a transparent appearance.

6. An improved tanning process using the composition claimed in claim 1, wherein the steps comprise:

a) treating a delime substrate to be tanned with 0.1 to 5% w/w of a composition as claimed in claim 1 in the presence of 10 to 60% water to adjust the pH in the range of 4.8 to 5.8, and then draining the float to obtain a pretreated substrate;

b) treating the pretreated substrate obtained in step [ a ] with 0.2 to 2.0% of a conventional fatliquor and 0.2 to 1.0% of an alkali metal salt of an organic acid having a carbon chain length of not more than 2 for a period of time in the range of 20 to 60 minutes;

c) treating the substrate obtained in step [ b ] with 3 to 50% of a conventional tanning agent added in one or more portions for a period of time ranging from 90 to 600 minutes while checking that the pH is in the range of 3.6 to 4.4, to obtain tanned leather.

7. A method as claimed in claim 6, wherein the conventional fatliquor used is selected from cationic fatliquors, acid-stabilized fatliquors, universal fatliquors, chromium-stabilized fatliquors, alone or in different combinations.

8. A process as claimed in claim 6, wherein the alkali metal salts of organic acids used are selected from sodium formate, sodium acetate, alone or in different combinations.

Technical Field

The present invention relates to a composition for pretreatment in waterless tanning. More particularly, the present invention relates to compositions that find use in tanning, wherein the compositions use intrinsic water present in the substrate to be tanned, thereby eliminating the need for added external water. The developed composition is used in the leather processing industry for the preparation of chrome or vegetable tanned leather in an environmentally friendly manner without increasing environmental pollution.

Background

Large amounts of water are used during leather processing, which results in the discharge of significant amounts of waste water (Rao et al, Journal of cleaner Production,11, 591-. Researchers around the world have participated in technology development to minimize the use of water in leather processing. Due to its versatility, chrome tanning is a widely used method for preparing leather. Vegetable tanning processes are also popular due to their environmental friendliness compared to chrome, although less than 20% of leather production worldwide uses this tanning process. Nevertheless, the partial pickling process and water are still used during vegetable tanning. The use of water during chrome tanning is extremely important to obtain uniform diffusion, distribution and hydrolysis of the chrome. The consumed chromium solution contains 1500-. Chromium emissions are a major problem, and a total of 2ppm of chromium is a regulated standard for tannery wastewater emissions in inland waters (Suresh et al, Journal of Cleaner Production,9,483-491, 2001). Therefore, alternative technologies to reduce chromium pollution or alternative tanning systems are needed to address the current situation. As there is no alternative tanning agent that is most suitable, it seems more appropriate to continue to use trivalent chromium as the main tanning material and manage it by reducing contamination at the source or end.

Although the use of chromium drainage aids, high drainage chromium tanning salts and chromium reduction techniques have been developed (WO 2014162059a1), they are lacking in commercial use. The method of chromium recovery and reuse is a very simple and effective method for solving chromium contamination, which is commercially practiced in many countries including India (Rao et al, Journal of Cleaner production,11,591-599, 2003). Pickling-basification free chrome tanning is another commercially viable development, where chrome tanning is carried out at elevated pH without the use of common salts. In addition, basification is not necessary in this process (Legesse et al, The Journal of The American Leather Chemists Association,97, 475-. Nevertheless, the disclosed process uses a large amount of aqueous medium and discharges waste water with a considerably lower pollution load than conventional pickling-based chrome tanning systems.

In addition, researchers have also considered alternative media for using water during chrome tanning. Silambarasan et al (RSC Advances,5,66815-66823,2015) have shown that as an alternative to water, chrome tanning can be carried out in ethanol and its derivatives. Similarly, The use of pressurized carbon dioxide as a vehicle for chrome tanning has been reported (Manfred et al, The Journal of Supercritical Fluids,66, 291-. Recent studies have shown that a minimum of 55-65% internal moisture content within the collagen matrix is required for the preparation of chrome tanned leathers of comparable quality (Silambarasan et al, Journal of Cleaner Production,87, 567-.

Dispersant compositions were developed for tanning without water or any other vehicle (WO 2017009867). The dispersant essentially comprises a polyalkylene polyol, an organic acid and a nonionic surfactant. The major component of the dispersant is a polyalkylene polyol, which will increase the cost of the composition and will limit commercial viability. Our co-pending indian patent application No. 201611009091 provides an anhydrous chrome tanning process that eliminates the use of water, salt, sulphuric acid and alkalising salts during the chrome tanning process. This process has gained more attention in the global leather industry and has been adopted by some tanners in india. However, the use of more water and expensive organic acids for pretreatment poses problems for implementation in a commercial environment. Therefore, the global leather industry has a slow absorption of these new anhydrous chrome tanning technologies, thus threatening the sustainability of the leather industry.

As can be seen in the prior art, current knowledge of cleaner chrome tanning and other chrome control options is well known. For vegetable tanning, many cleaner technologies have not been developed. The prior art has focused on technologies such as anhydrous chrome tanning, dispersants for anhydrous tanning, and the like. In short, it can be concluded that during the tanning process, water is used to favour the distribution and penetration of the tanning salts in the matrix, and that, according to the currently available literature, the following drawbacks are associated with the prior art:

the use of water and the production of chromium-containing waste water during chrome tanning;

reduced absorption of chrome tanning agent by the substrate;

release of large amounts of neutral salts due to pickling and basification processes;

use of partial pickling and water during plant tanning;

thus, continuing to focus on the disadvantages of the prior art reported so far and the problems associated with the available prior art, the inventors of the present invention have recognized that there is an urgent need to provide compositions and methods for pretreatment during anhydrous chrome tanning which help eliminate water during tanning and thereby reduce wastewater discharge. The elimination of mineral tanning salts and common salts would reduce the pollution load and chemical reagent costs of the tanning process, thereby benefiting the industry.

Objects of the invention

It is therefore a main object of the present invention to provide a composition useful in the pre-treatment in a waterless tanning process, which avoids the limitations as described above.

Another object of the invention is to avoid the use of water during chrome and vegetable tanning and to utilize the inherent water present in the substrate.

It is yet another object of the present invention to use chemical aids, such as acid stable cationic fatliquor, during the tanning process.

It is a further object of the invention to improve the absorption of chromium and vegetable tannins during the process.

It is yet another object of the present invention to reduce the pollution load and toxic chemicals in the effluent.

It is yet another object of the present invention to reduce the processing time, water and cost of pretreatment during waterless tanning as compared to conventional processing.

It is yet another object of the present invention to eliminate the use of salt, sulfuric acid and alkalization processes as compared to conventional treatments.

Disclosure of Invention

The present invention provides a composition useful in the pretreatment in a waterless tanning process, wherein the composition comprises:

90 to 95% (v/v) of an organic acid having a carbon chain length in the range of C1 to C3;

ii.3 to 8% (v/v) primary alcohols having a carbon chain length in the range of C1 to C3; and

iii.2 to 5% (v/v) of a nonionic surfactant.

The present invention provides a process for preparing a pretreatment composition useful in waterless tanning comprising mixing 90 to 95% (v/v) of an organic acid having a carbon chain length in the range of C1 to C3, 3 to 8% (v/v) of a primary alcohol having a carbon chain length in the range of C1 to C3, and 2 to 5% (v/v) of a nonionic surfactant for a period of time in the range of 5 to 30 minutes to obtain the composition. The composition is water soluble, exhibits a pH in the range of 1.8 to 2.6 as a 10% solution, and is characterized by a transparent appearance.

In one embodiment, the invention provides a waterless tanning process using the developed composition, wherein the steps comprise:

i. treating the delime substrate to be tanned with 0.1 to 5% w/w of the developed composition in the presence of 10 to 60% water to adjust the pH in the range of 4.8 to 5.8, then draining the float (float) to obtain a pretreated substrate,

treating the pretreated substrate obtained in step (i) with 0.2 to 2.0% of a conventional fatliquor (fattiquor) and 0.2 to 1.0% of an alkali metal salt of an organic acid having a carbon chain length not exceeding 2 for a period of time in the range of 20 to 60 minutes,

treating the substrate obtained in step (ii) with 3 to 50% of a conventional tanning agent added in one or more portions for a period of time ranging from 90 to 600 minutes while checking that the pH is in the range of 3.6 to 4.4 to obtain a tanned substrate.

In one embodiment of the present invention, the organic acids used may be selected from formic acid, acetic acid, propionic acid, alone or in different combinations.

In another embodiment of the present invention, the primary alcohols used may be selected from methanol, ethanol, propan-2-ol, alone or in different combinations.

In a further embodiment of the present invention, the nonionic surfactant used may be selected from 2- [4- (2,4, 4-trimethylpent-2-yl) phenoxy ] ethanol, polyoxyethylene (20) sorbitan monooleate, [2- [ (2R,3S,4R) -3, 4-dihydroxytetrahydrofuran-2-yl ] -2-hydroxyethyl ] stearate, alone or in different combinations.

In another embodiment of the present invention, the conventional fatliquor used may be selected from cationic fatliquors, acid-stabilized fatliquors, universal fatliquors, chromium-stabilized fatliquors, either alone or in different combinations.

In a further embodiment of the invention, the alkali metal salts of organic acids used may be selected from sodium formate, sodium acetate, alone or in different combinations.

Detailed Description

The present invention provides a process for preparing a composition comprising mixing together 90 to 95% (v/v) of an organic acid having a carbon chain length in the range of C1 to C3, 3 to 8% (v/v) of a primary alcohol having a carbon chain length in the range of C1 to C3, and 2 to 5% (v/v) of a non-ionic surfactant for a period of 5 to 30 minutes to obtain a pre-treated composition useful in an anhydrous tanning process.

The composition prepared had the following characteristics:

pH of 10% solution: 1.8 to 2.6

Color: is transparent

Solubility in water: height of

The composition is used in a waterless tanning process as described below.

Treating a deliming substrate with from 0.1 to 5% of the composition in the presence of 10-60% water. The pH of the skins was adjusted to be in the range of 4.8 to 5.8. After the pH is obtained, the float is drained and the substrate is treated with 0.2 to 2.0% of a conventional fatliquor and 0.2 to 1.0% of an alkali metal salt of an organic acid having a carbon chain length of not more than 2. After a period of time of 20 to 60 minutes, the substrate is treated with 3 to 50% of a conventional tanning agent added in one or more portions for a period of time in the range of 90 to 600 minutes. The pH was checked in the range of 3.6 to 4.4 to obtain a tanned substrate.

The inventive step of the present invention is to prepare the composition by judicious selection and combination of key chemicals so that the resulting composition can be easily used for pretreatment in waterless tanning, which will help to perform tanning more efficiently and to easily use the inherent moisture content of the raw materials to reduce effluent emissions. Furthermore, the elimination of common salts and the substantial reduction in water requirements, process duration and cost are achieved in the new invention.