CN110914460A

CN110914460A - Dispersant composition for tanning and preparation process thereof

Info

Publication number: CN110914460A
Application number: CN201880044716.8A
Authority: CN
Inventors: C·穆拉利达拉恩
Original assignee: Council for Scientific and Industrial Research CSIR
Current assignee: Council of Scientific and Industrial Research CSIR; Council for Scientific and Industrial Research CSIR
Priority date: 2017-05-25
Filing date: 2018-04-17
Publication date: 2020-03-24
Also published as: EP3635141A1; BR112019024702A2; WO2018216029A1; ZA201907934B; EP3635141A4

Abstract

Disclosed herein are dispersant compositions consisting essentially of an alkali metal salt of an organic acid, a diatomaceous earth derivative, and a suitably modified sensitizer. The composition finds application in the leather processing industry for tanning without adding any water or any other medium. It was found to have great application potential in the tanning industry ensuring eco-friendly leather processing which does not increase environmental pollution due to no effluent production. It is therefore envisaged that the present invention plays a key role in enhancing the economic and environmental benefits associated with the tanning industry. The present disclosure also relates to a process for preparing the composition and an eco-friendly tanning process using the composition.

Description

Dispersant composition for tanning and preparation process thereof

Subject matter of the invention

Improved dispersant compositions for use in tanning and processes for their preparation.

Technical Field

The present invention relates to an improved dispersant composition for use in tanning. More particularly, the present invention relates to a dispersant composition to promote the tanning of hide/skin (skin) without the addition of extraneous water. The invention also provides a preparation process of the dispersant composition. The composition of the present invention finds wide application in the leather processing industry as an important adjuvant for the purpose of tanning hides and skins without adding extraneous water to the tanning tank (tanning bath). Thus, the composition provides an eco-friendly solution for leather tanning that does not produce effluent.

Background

Leather manufacturing involves the use of large quantities of water in order to convert raw hides and skins into finished leather. Typically, in leather processing, the preserved hides and skins are initially treated with water to rehydrate the skins. Subsequently, they are treated with lime and sulfide or enzymes to facilitate the removal of hair and meat that adhere to the skin layer. At this stage the material is called liminate (limedpile). These pelts (pelts) were then processed in a wooden drum using water as the processing medium. Pelts are treated with acid salts to remove residual lime and short hairs present in an operation known as deliming and bating. This procedure uses about 2-3L of water per kg of pelts. The medium is then discharged as an effluent. Sometimes, degreasing for removing excess fat is also performed together with deliming and softening. The pelts are subsequently treated with 1-2L of water per kg of pelts, together with salt and acid, to adjust from a pH of about 8.0 of the pelts to a pH of 2.5-2.8. This operation is called pickling. The used medium is discharged again as a salt-rich effluent. The pickled pelts are then treated with about 2-3L of water per kg of material, together with a mixture of 8% chromium-based tanning agent and alkali (alkalies), in a process known as chrome tanning. The material obtained at the end of chrome tanning is called "Wet blue leather" (Wet leather). The pH of the leather will be in the range of 3.8-4.0.

Sometimes, the pelts are treated with vegetable tannins instead of chromium. The leathers obtained by this process are known as vegetable tanned leathers.

Essentially all of these operations use water as the medium in the drum to produce leather of defined quality. Worldwide, this is still a practice in leather manufacture, and in order to convert pelts into tanned leathers, almost 5-6L of water is employed, which involves intermittent washing of the leather between various operations.

However, on the one hand the demand for water poses serious usability problems and since most of the water is discharged as effluent, the treatment of large amounts of effluent containing all residual chemicals is another major environmental challenge. Worldwide, nearly 30,000 metric tons of hides and skins are processed per day, resulting in the use of about 750 million liters of water per day. The same amount of water with high salinity, chromium residues and other unused chemicals per day needs to be treated as effluent. This practice has threatened the sustainability of leather manufacture.

Efforts are being made to avoid the use of water in leather processing. Our co-pending patent application (85/Del/2014) has provided dispersants involving basic chromium sulfate as one of the components of the composition. The composition finds wide application in waterless, acid-free tanning. However, a major limitation associated with this composition is that the presence of basic chromium sulphate limits its use only in chrome tanning, thereby limiting its broader application in other fields such as vegetable tanning.

This has prompted further research whereby our other co-pending patent application 2104/del/2015 has provided a chromium-free dispersant composition comprising a polyalkylene polyol, a carbonyl and/or hydroxyl compound and a non-ionic surfactant. The dispersant composition finds application as an adjuvant in any type of tanning, without the addition of extraneous water. However, the main limitation associated with such compositions is that as a liquid product, when solid tanning agents are employed in large quantities, they give rise to problems of homogeneity and consistency in tanning.

Object of the Invention

The main object of the present invention is to provide an improved dispersant composition for use in tanning which obviates the limitations as set forth above.

Another object is to provide a dispersant composition to promote any tanning without the addition of extraneous water.

Still another object of the present invention is to provide a solution for producing effluent (effluent) in leather tanning.

Summary of The Invention

Accordingly, the present invention provides a dispersant composition for use in tanning, wherein the composition comprises:

alkali metal salts of organic acids having 1 to 6 carbon atoms;

diatomaceous earth or its derivatives and

(ii) a size optionally pre-treated with 50-100% w/w reducing sugar,

wherein the ratio of (a) to (b) to (c) is in the range of 5:3:9 to 40:1:1 and a 10% aqueous solution of the composition exhibits a pH in the range of 1.0 to 4.0.

In an embodiment of the invention, the alkali metal salt is selected from the group consisting of sodium formate, sodium acetate and sodium citrate.

In another embodiment of the invention, the acid used for pH adjustment is selected from the group consisting of sulfamic acid, citric acid, oxalic acid, alone or in any combination.

In yet another embodiment of the present invention, the sensate used is selected from calcium chloride or urea.

In another embodiment of the invention, the derivative of diatomaceous earth is silica.

In another embodiment of the present invention, the reducing sugar used is selected from the group consisting of glucose, galactose and fructose.

Further, the present invention provides a process for preparing a dispersant composition comprising:

optionally treating the size agent with 50% -100% w/w reducing sugar under stirring conditions to obtain a sugar-pretreated size agent,

(ii) treating a susceptor such as obtained in step (i) at 2% to 9% w/w or sugar-pretreated susceptor with an alkali metal salt of an organic acid in the presence of 1% to 3% w/w of diatomaceous earth or a derivative thereof added simultaneously or in a different succession (in differential treatment) under continuous stirring for a period of not less than 30 minutes, and

the pH of the dispersant composition is adjusted so that the pH of a 10% aqueous solution of the composition is in the range of 1-4.

In an embodiment of the invention, the alkali metal salt used in the process is selected from the group consisting of sodium formate, sodium acetate and sodium citrate.

In another embodiment of the invention, the sensate used in the process is selected from calcium chloride or urea.

Further, the present invention provides a tanning process using the dispersant as claimed in claim 1, comprising treating delimed pelts with the dispersant and the tanning agent in a ratio of 1:1 to 1:20 for a period of not less than 3 hours to obtain tanned leathers.

Detailed Description

The process of the present invention is described in detail below.

Optionally, the size is treated with 50% to 100% w/w reducing sugar under stirring. 2% to 9% w/w of the resulting sugar-pretreated gum-sensing agent is added to the alkali metal salt of an organic acid. The process includes the option of adding the amount of size without pre-treating it with reducing sugars. Also added to the mixture is 1% to 3% w/w of diatomaceous earth or derivatives thereof. The addition is carried out simultaneously or in different succession under stirring. After treatment for a period of not less than 30 minutes, the pH of a 10% aqueous solution of the resulting substrate is adjusted to a range of 1-4 to obtain an improved dispersant composition.

The improved dispersant composition of the present invention exhibits the following composition

I

a) Alkali metal salts of organic acids having carbon chain lengths in the range of one to three

b) Diatomaceous earth or derivatives thereof

c) (ii) a susceptor optionally pretreated with 50-100% w/w reducing sugar, wherein (a): (b): c) is in the range of 5:3:9 to 40:1: 1.

pH of 10% solution of composition: 1 to 4

The improved dispersants are used for tanning in the following manner

Delimed pelts are treated with the improved dispersant and tanning agent in a ratio of 1:1 to 1:20 for a period of not less than 3 hours to obtain tanned leathers.

The inventive step of the present invention consists in incorporating the size-sensing agent and diatomaceous earth into the alkali metal salt of an organic acid to ensure that the tanning agent is uniformly dispersed, thereby providing a solution to the lack of consistency in tanning as encountered in the prior art.

The following examples are given by way of illustration only and therefore should not be construed to limit the scope of the present invention.

Example 1

150 grams of calcium chloride was mixed with 45 grams of silica for 15 minutes. The product obtained is added to 270 g of sodium formate with stirring. After a period of 20 minutes, 270 grams of citric acid was added to the above mixture with continuous stirring and the pH was adjusted to 2.8 to obtain the improved dispersant composition of the present invention.

The dispersant was then analyzed and the composition was found to be as follows:

a) sodium formate

b) Silicon dioxide

c) Calcium chloride

Wherein (a), (b), (c) are 6:1:3.3

pH of 10% solution of composition: 2.8

The improved dispersant composition was then used for chrome tanning in the following manner:

ten goat delimed pelts weighing 10kg were treated with 300 g of the above dispersant and 300 g of basic chromium sulfate for a period of 3 hours to obtain wet blue leather.

Example 2

2 kg of calcium chloride was mixed with 4 kg of silica for 30 minutes. The resulting product was added to 34 kg of sodium formate with stirring. After a period of 30 minutes, 32 kg of sulfamic acid and 8 kg of citric acid were added to the above mixture with continuous stirring and the pH was adjusted to 2.5 to obtain the improved dispersant composition of the present invention.

I

a) sodium formate

b) Silicon dioxide

c) Calcium chloride

Wherein (a), (b), (c) are 17:2:1

pH of 10% solution of composition: 2.5

Five cows weighing 50kg delimed pelts were treated with 1250 g of the above dispersant and 3250 g of basic chromium sulphate for 8 hours to obtain wet blue leather, saving 200L of water conventionally used.

Example 3

15 grams of urea was mixed with 10 grams of glucose to obtain glucose treated urea, which was mixed with 5 grams of silica for 20 minutes. The resulting product was added to 200 grams of sodium acetate with stirring. After a period of 20 minutes, 20 grams of oxalic acid was added to the mixture with continuous stirring and the pH was adjusted to 4.0 to obtain the improved dispersant composition of the present invention.

I

a) sodium acetate

b) Silicon dioxide

c) Urea

Wherein (a), (b), (c) are 40:1:3

pH of 10% solution of composition: 4.0

Ten delimed sheep pelts weighing 10kg were treated with 200 g of the above dispersant and 1500 g of acacia bark (wattle) extract for 5 hours to obtain vegetable tanned leathers.

Example 4

5 grams of urea was mixed with 2.5 grams of fructose for 15 minutes fructose treated urea which was then mixed with 5 grams of silica for 20 minutes. The resulting product was added to 50 grams of sodium citrate with stirring. After a period of 20 minutes, 30 grams of citric acid was added to the above mixture with continuous stirring and the pH was adjusted to 1.0 to obtain the improved dispersant composition of the present invention.

I

a) citric acid sodium salt

b) Silicon dioxide

c) Urea

Wherein (a), (b), (c) are 10:1

pH of 10% solution of composition: 1.0

Ten goat delimed pelts weighing 10kg were treated with 500 g of the above dispersant and 600 g of modified glutaraldehyde for 3 hours to obtain aldehyde-tanned leathers.

The biological resource used in the present invention is delimed pelts obtained from: suppliers, Abdul kareem, Tanners, trains of quality finishes, Semi Finished Leathers and Hides & Skins, Chemicals and Tanning Materials (trade companies for high quality Finished goods, Semi Finished leather and hide and skin, Chemicals and Tanning Materials), 57, narayan Street, pudipet, Chennai-600002.

Advantages of the invention

The following are the advantages of the invention:

the dispersant composition is suitable for any type of tanning.

The preparation process of the composition is very simple and cost effective.

The use of the composition of the invention for leather tanning is suitable for all kinds of raw materials.

The use of the composition of the invention for leather tanning ensures the complete elimination of the use of water and common salts for tanning, avoiding the production of tanning effluents.

The composition of the present invention ensures a uniform and consistent result when used for leather tanning.

Claims

1. A dispersant composition for use in tanning, wherein the composition comprises:

a) alkali metal salts of organic acids having 1 to 6 carbon atoms;

b) diatomaceous earth or a derivative thereof; and

c) (ii) a size optionally pre-treated with 50-100% w/w reducing sugar,

2. The dispersant composition of claim 1, wherein the alkali metal salt is selected from the group consisting of sodium formate, sodium acetate, and sodium citrate.

3. The dispersant composition of claim 1, wherein the acid for pH adjustment is selected from the group consisting of sulfamic acid, citric acid, oxalic acid, alone or in any combination.

4. The dispersant composition of claim 1, wherein the size-sensing agent used is selected from calcium chloride or urea.

5. The dispersant composition of claim 1, wherein the derivative of diatomaceous earth is silica.

6. A dispersant composition according to claim 1, wherein the reducing sugar used is selected from the group consisting of glucose, galactose and fructose.

7. A process for preparing a dispersant composition, comprising:

i. optionally treating the size agent with 50% -100% w/w reducing sugar under stirring conditions to obtain a sugar-pretreated size agent;

treating a susceptor such as obtained in step (i) at 2% to 9% w/w or a sugar-pretreated susceptor with an alkali metal salt of an organic acid in the presence of 1% to 3% w/w of diatomaceous earth or a derivative thereof added simultaneously or in a different succession with continuous stirring for a period of not less than 30 minutes, and

adjusting the pH of the dispersant composition such that the pH of a 10% aqueous solution of the composition is in the range of 1-4.

8. The process of claim 7, wherein the alkali metal salt is selected from the group consisting of sodium formate, sodium acetate, and sodium citrate.

9. The process of claim 7, wherein the gum-sensing agent is selected from calcium chloride or urea.

10. A tanning process using the dispersant of claim 1, comprising treating delimed pelts with the dispersant and tanning agent in a ratio of 1:1 to 1:20 for a period of not less than 3 hours to obtain tanned leathers.