Indian Patents. 272914:A LEATHER RETANNING COMPOSITION AND PROCESS OF PRODUCTION THEREOF

Title of Invention	A LEATHER RETANNING COMPOSITION AND PROCESS OF PRODUCTION THEREOF
Abstract	This invention relates to an improved retanning composition for producing software and fuller leather. This composition consists of a pseudo emulsion obtained by polymerizing acrylic monomers in the presence of vegetable and/or mineral oils. The pseudo polymer obtained may be used to retan chrometanned hides and skins in the retanning and fat liquoring stage and/or at rechrome stage.

Full Text	FORM 2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION Section 10; rule 13 TITLE A leather retanning composition, a process for producing the same and a method of retanning leather therewith APPLICANT Balmer Lawrie & Co. Ltd. An Indian company of Leather Chemical Division Manali, Chennai 600 068 India The following specification particularly describes the nature of this invention and the manner in which it is to be performed This invention relates to improved and novel leather retanning composition, a process for producing the same and a method of retanning leather therewith. This composition is a pseudopolymeric emulsion containing acrylic polymers and vegetable oils and/or mineral oils and mixtures thereof. During processing, skins and hides are subjected to retanning steps to impart qualities of softness and fullness to processed leather. Softness and fullness of leather attribute such qualities to the final finished products. Various retanning processes are known in the art. Different retanning compositions are also used by the leather industry for imparting the desired qualities of softness and fullness to processed leather. As in the case of many industries researchers constantly try to improve upon the existing quality of their products preferably with cost effectiveness. With the object of developing leather from skins and hides with increased softness, fullness and suppleness, an improved retanning composition has been developed by us. This composition is a pseudo emulsion containing polymers and oils. Polymers of this composition have acrylic monomers such as methacrylate, methacrylic/acrylic acid, ethyl long chain acrylate and oils that form a part of the retanning composition may be vegetable oils, synthetic and natural hydrocarbon based oils such as lubricating oils, oil esters and mixtures of them. Copolymerization of the acrylic monomers are affected in the presence of one or more of the oils specified herein before. The reaction is carried out at a pH of 3±0.5 using appropriate polymerization catalyst known in the art. Polymerization is preferably carried out at 70 to 80°C. The resultant product may be neutralized before use as retanning agent. Retanning agent may be incorporated at retanning and fat liquoring stage. The pseudo emulsified retanning composition or agent of this invention is found to produce suppleness, fullness as well -2- as softness to the final product. Yet another advantage of using this retanning composition is that the retanning process may be carried out at a pH as low as 3 and produces a stable bath at the rechroming stage. Conventional process for retanning may be followed with the addition of the novel pseudo emulsion composition of this invention. The following flow chart is illustrative of the retanning process with the composition of this invention:- W/B cow (chrome-tanned) ¤ Washing ¤ Acidification to pH 3 to 3.2 ¤ Rechroming with basic chrome sulphate and chromium syntan ¤ Adding composition of this invention ¤ Barification to pH 4 with the addition of sodium formate and sodium bicarbonate ¤ Neutralizing ¤ Raising the pH to 5.2 with neutralizing syntan ¤ Addition of retanning composition of this invention, dye and fat liquor -3- ¤ Fixing by the addition of formic acid ¤ Drying in air ¤ Finished leather The leather retanning composition according to this invention comprises a polymeric emulsion obtained by polymerizing acrylic monomers in the presence of at least one vegetable or mineral oil or mixtures thereof. The process for producing a leather processing composition according to this invention comprises the step of catalytically polymerizing acrylic monomers in the presence of at least one vegetable or mineral oil or mixtures thereof and neutralizing the resultant pseudo emulsion containing said oil incorporated in the polymeric entity. The method of leather processing according to this invention comprises the step of adding a retanning composition containing a pseudo emulsion of acrylic polymers incorporated with vegetable or mineral oils or mixtures thereof at least at the rechrome stage, neutralizing thus treated leather and processing said treated leather in the convention manner. The following examples are only illustrative of this invention which may be carried out in modified and altered manner known to persons skilled in the art. -4- Example I: A process for preparing pseudo emulsion acrylic polymer incorporating vegetable and/or mineral oils therein. 85 - 100 parts by weight acrylic acidmonomer. 5-15 parts by weight of 2 ethyl hexyl acrylate. 20 - 40 parts by weight of any vegetable oil such as caster oil or mineral oil such as lubricating oil. This mixture is subjected to copolymerization at 70 to 80°C for three hours in the presence of any known polymerization catalyst. Sodium metabisulphite and potassium presulphate are used as polymer initiators. After three hours an emulsion containing 30% of active matter with a viscosity of 3500 to 4500 is obtained at a pH of 3 ± 0.5. The product is found to be fairly soluble in water. On a commercial scale, the pseudo emulsion may be prepared by the following method. Acrylic acid - 95 kg 2 ethyl hexyl acrylate - 5 kg Castor oil - 27 kg Sodium metabisulphite - 1 kg Potassium persulphate - 2 kg Process water from previous operations - 287 kg Caustic lye (48%) - 7 kg -5- A reactor is charged with 187 kg of process water followed by 27 kg of castor oil and 1 kg of sodium metabisulphite and this mixture is pumped into a monomer tank. 2 kg of potassium persulphate is dissolved in 100 kg of process water and pumped into an initiator tank. When the contents of the reactor attain a temperature of 70 to 75°C, 1% of the initiator solution is charged into the reactor followed by simultaneous addition of monomer and initiator solutions for about 3 hours while maintaining the temperature at 70 to 75°C. The improvement is that no external emulsifier is added to this reaction system and the water insoluble castor oil goes into the polymerized product with the presence of 2-ethyl hexyl acrylate or any such hydrophobic monomer which is used, thereby forming a pseudo emulsion. After completion of addition, the reaction is continued for about 1 hour while maintaining the temperature at 70 to 75°C. 75 kg of caustic lye is slowly added over a period of 30 minutes and the reactor is cooled to 50 - 55°C. The pH of the resultant mass is adjusted to 3 to 3.5. Retanning is carried out with this product as shown in the flowchart to produce leather with improved fullness and inner softness. Addition of the improved retanning composition reduces fat liquor consumption by 5 - 10%. The retanning process with this composition may be carried out at very low pH. These are added advantage of using the improved composition.

Full Text

FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
COMPLETE
SPECIFICATION
Section 10; rule 13
TITLE
A leather retanning composition, a process for producing the same
and a method of retanning leather therewith
APPLICANT
Balmer Lawrie & Co. Ltd.
An Indian company
of Leather Chemical Division
Manali, Chennai 600 068
India
The following specification particularly describes
the nature of this invention and the manner
in which it is to be performed

This invention relates to improved and novel leather retanning composition, a process for producing the same and a method of retanning leather therewith. This composition is a pseudopolymeric emulsion containing acrylic polymers and vegetable oils and/or mineral oils and mixtures thereof.
During processing, skins and hides are subjected to retanning steps to impart qualities of softness and fullness to processed leather. Softness and fullness of leather attribute such qualities to the final finished products. Various retanning processes are known in the art. Different retanning compositions are also used by the leather industry for imparting the desired qualities of softness and fullness to processed leather.
As in the case of many industries researchers constantly try to improve upon the existing quality of their products preferably with cost effectiveness. With the object of developing leather from skins and hides with increased softness, fullness and suppleness, an improved retanning composition has been developed by us. This composition is a pseudo emulsion containing polymers and oils. Polymers of this composition have acrylic monomers such as methacrylate, methacrylic/acrylic acid, ethyl long chain acrylate and oils that form a part of the retanning composition may be vegetable oils, synthetic and natural hydrocarbon based oils such as lubricating oils, oil esters and mixtures of them. Copolymerization of the acrylic monomers are affected in the presence of one or more of the oils specified herein before. The reaction is carried out at a pH of 3±0.5 using appropriate polymerization catalyst known in the art. Polymerization is preferably carried out at 70 to 80°C. The resultant product may be neutralized before use as retanning agent. Retanning agent may be incorporated at retanning and fat liquoring stage. The pseudo emulsified retanning composition or agent of this invention is found to produce suppleness, fullness as well
-2-

as softness to the final product. Yet another advantage of using this retanning composition is that the retanning process may be carried out at a pH as low as 3 and produces a stable bath at the rechroming stage. Conventional process for retanning may be followed with the addition of the novel pseudo emulsion composition of this invention.
The following flow chart is illustrative of the retanning process with the composition of this invention:-
W/B cow (chrome-tanned)
¤
Washing
¤
Acidification to pH 3 to 3.2
¤
Rechroming with basic chrome sulphate and chromium syntan
¤
Adding composition of this invention
¤
Barification to pH 4 with the addition of sodium formate and sodium bicarbonate
¤
Neutralizing
¤
Raising the pH to 5.2 with neutralizing syntan
¤
Addition of retanning composition of this invention, dye and fat liquor
-3-

¤
Fixing by the addition of formic acid
¤
Drying in air
¤
Finished leather
The leather retanning composition according to this invention comprises a polymeric emulsion obtained by polymerizing acrylic monomers in the presence of at least one vegetable or mineral oil or mixtures thereof.
The process for producing a leather processing composition according to this invention comprises the step of catalytically polymerizing acrylic monomers in the presence of at least one vegetable or mineral oil or mixtures thereof and neutralizing the resultant pseudo emulsion containing said oil incorporated in the polymeric entity.
The method of leather processing according to this invention comprises the step of adding a retanning composition containing a pseudo emulsion of acrylic polymers incorporated with vegetable or mineral oils or mixtures thereof at least at the rechrome stage, neutralizing thus treated leather and processing said treated leather in the convention manner.
The following examples are only illustrative of this invention which may be carried out in modified and altered manner known to persons skilled in the art.
-4-

Example I:
A process for preparing pseudo emulsion acrylic polymer incorporating vegetable and/or mineral oils therein.
85 - 100 parts by weight acrylic acidmonomer.
5-15 parts by weight of 2 ethyl hexyl acrylate.
20 - 40 parts by weight of any vegetable oil such as caster oil or mineral oil such as lubricating oil.
This mixture is subjected to copolymerization at 70 to 80°C for three hours in the presence of any known polymerization catalyst. Sodium metabisulphite and potassium presulphate are used as polymer initiators. After three hours an emulsion containing 30% of active matter with a viscosity of 3500 to 4500 is obtained at a pH of 3 ± 0.5. The product is found to be fairly soluble in water.
On a commercial scale, the pseudo emulsion may be prepared by the following method.
Acrylic acid - 95 kg
2 ethyl hexyl acrylate - 5 kg
Castor oil - 27 kg
Sodium metabisulphite - 1 kg
Potassium persulphate - 2 kg
Process water from previous operations - 287 kg
Caustic lye (48%) - 7 kg
-5-

A reactor is charged with 187 kg of process water followed by 27 kg of castor oil and 1 kg of sodium metabisulphite and this mixture is pumped into a monomer tank. 2 kg of potassium persulphate is dissolved in 100 kg of process water and pumped into an initiator tank.
When the contents of the reactor attain a temperature of 70 to 75°C, 1% of the initiator solution is charged into the reactor followed by simultaneous addition of monomer and initiator solutions for about 3 hours while maintaining the temperature at 70 to 75°C. The improvement is that no external emulsifier is added to this reaction system and the water insoluble castor oil goes into the polymerized product with the presence of 2-ethyl hexyl acrylate or any such hydrophobic monomer which is used, thereby forming a pseudo emulsion. After completion of addition, the reaction is continued for about 1 hour while maintaining the temperature at 70 to 75°C. 75 kg of caustic lye is slowly added over a period of 30 minutes and the reactor is cooled to 50 - 55°C. The pH of the resultant mass is adjusted to 3 to 3.5.
Retanning is carried out with this product as shown in the flowchart to produce leather with improved fullness and inner softness.
Addition of the improved retanning composition reduces fat liquor consumption by 5 - 10%. The retanning process with this composition may be carried out at very low pH. These are added advantage of using the improved composition.

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Patent Number

272914

Indian Patent Application Number

578/CHE/2006

PG Journal Number

19/2016

Publication Date

06-May-2016

Grant Date

03-May-2016

Date of Filing

29-Mar-2006

Name of Patentee

BALMER LAWRIE & CO LTD

Applicant Address

AN INDIAN COMPANY OF LEATHER CHEMICAL DIVISION,MANALI, CHENNAI 600 068, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	RAJADURAI RAJMOHAN	C/O BALMER LAWRIE & CO. LTD., LEATHER CHEM, DIVISION, MANALI, CHENNAI 600 068,
2	JAYANTA KUMAR BASU,	C/O BALMER LAWRIE & CO. LTD., LEATHER CHEM, DIVISION, MANALI, CHENNAI 600 068,
3	SUNDARARAMAN RAMAKRISHNA SUBRAMANIAN	C/O BALMER LAWRIE & CO. LTD., LEATHER CHEM, DIVISION, MANALI, CHENNAI 600 068,
4	ANIMESH CHATTOPADHYAH	C/O BALMER LAWRIE & CO. LTD., LEATHER CHEM, DIVISION, MANALI, CHENNAI 600 068,
5	SUBRAHMANYAM RAVIKUMAR	C/O BALMER LAWRIE & CO. LTD., LEATHER CHEM,DIVISION, MANALI, CHENNAI 600 068,

PCT International Classification Number

C14C 3/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA