WO1994012563A1

WO1994012563A1 - Method of producing collagen-containing semi-finished product

Info

Publication number: WO1994012563A1
Application number: PCT/NZ1993/000117
Authority: WO
Inventors: Irina Markovna Ermakova
Original assignee: Miller, James, Kenneth
Priority date: 1992-11-23
Filing date: 1993-11-23
Publication date: 1994-06-09
Also published as: AU5579494A; RU2018540C1

Abstract

Methods for producing high-molecular products from materials containing collagen which may be used in light industry in the manufacture of leather-like material are described. A mass is produced from leather raw material by means for machining and chemical processing. This mass contains broken up collagen and partially separated collagen free proteins. It is frozen, and after thawing undergoes final processing to produce semi-finished product. To obtain a semi-finished product with a polymer structure with high physico-mechanical properties, untanned leather waste is used to prepare a collagen solution. A compound is also prepared from tanned leather waste with solid matter particles 0.2 to 0.6 mm in size. The solution and the compound are combined, filtered until the particles are 0.2-0.6 mm, cooled to 0-5 °C, and a cross-linking agent is added at the rate of 0.15-7.0 % by mass. The mixture is homogenised. It is then deep frozen at a temperature range of minus 14 °C to minus 75 °C for 0.1-2.0 hours and kept frozen at minus 2 °C to minus 20 °C. After thawing the polymer material obtained is left to lie at room temperature, wet for 6-12 hours, then heated to 85 - 105 °C, cooled to room temperature, treated with an al kali-saline solution with a pH of 9-10 for 10 to 20 minutes and wrung out until the residual moisture content is 30 - 40 %. Then the material is subjected to hot pressing and further exposed to air at no load for 12 - 24 hours. To give the semi-finished product a leather-like appearance it can be subjected to additional tanning processing.

Description

METHOD OF PRODUCING COLLAGEN-CONTAINING SEMI-FINISHED PRODUCT

Technical Field

The invention relates to methods for producing high- molecular products from materials containing collagen and may be used in the manufacture of leather-like material for producing leather fancy goods and footwear and for the manufacture of finishing material for use for construction_/ transportation and furniture manufacture purposes.

Background of the Invention

There are recognised methods for processing raw material containing collagen to make semi-finished product containing collagen from which product material containing collagen can be manufactured at a later stage. For example there is a recognised method for producing collagen-containing semi-finished product in the form of a collagen solution (see av. sv. No. 511062, 1974 class A 23Y 1/10). In this method the original leather raw material is subjected to machining and chemical processing from which a mass is produced which includes broken up collagen and partially separated collagen free proteins. This mass is frozen at a temperature of minus 10° to minus 30°C for one to two days and the frozen mass is allowed to stand for 1 to 2 days, to ensure compression of the fibres. After thawing the mass undergoes final processing, which ensures that the semi-finished product produced is in a ready state for subsequent use. Using this method collagen-containing semi-finished product can only be produced in the form of a solution, and this method cannot be used to produce film-like or leather-like materials.

Disclosure of the Invention

The aim of the proposed technical solution is production of collagen-containing semi-finished product with a polymer structure with high physico- mechanical properties. According to one aspect of the invention there is provided a method for producing a semi-finished collagen-containing material comprising the steps of

(i) preparing a collagen solution from untanned leather waste, (ϋ) combining the collagen solution with a composition comprising tanned leather waste, (iii) filtering the resulting homogeneous mass, (iv) cooling the homogeneous mass,

(v) adding a cross-linking agent to the resulting mass,

(vi) homogenising the resulting mixture,

(vii) freezing the resulting mixture,

(viii) thawing the frozen mixture, to obtain a polymer material, (ix) exposing the polymer material to air under no load, (x) heating then cooling to room temperature the resulting material, (xi) treating the resulting material with an alkali- saline solution,

(xii) reducing the moisture content by mechanical means, (xiii) hot pressing, and

(xiv) further exposing the material to air under no load, to produce the semi-finished collagen- containing material.

In one preferred form the invention involves a method for producing semi-finished product for the manufacture of collagen-containing materials, in which a mass, containing broken up collagen and partially separated collagen free proteins, is produced from leather raw material by means of machining and chemical processing, is frozen, and after thawing undergoes final processing to produce semi-finished product for future use, this method comprising:

- preparing a collagen solution from untanned leather waste,

- combining the collagen solution with a compound prepared from tanned leather waste with solid matter particles of 0.2 to 0.6 mm in size for 1 to 5 hours at a temperature no higher than 15°C to obtain a homogeneous mass containing 0.1 to 2% by mass untanned collagen and 0.3 to 10% by mass tanned collagen, and having a pH of 2.6 to 5.0,

- filtering the mass until its particles are 0.2 to 0.6 mm, - cooling the mass to 0 to 5°C,

- adding a cross-linking agent to the mass at a rate of 0.15 to 7.0% by mass, to produce a mixture,

- homogenising the mixture at a temperature no higher than 5°C, - freezing the homogenised mixture at minus 14°C to minus 75°C for 0.1-2.0 hours, and then at minus 2°C to minus 20°C for 4 to 24 hours, thawing the mixture to obtain a polymer material. processing the polymer material by exposing it to air at room temperature, wet, at no load, for 6 to 12 hours, heating it to 85°C to 105°C, cooling it to room temperature, treating it with an alkali- saline solution with a pH of 9 to 10 for 10 to 20 minutes and wringing it out until the residual moisture content is 30 to 40%, hot pressing the polymer material and further exposing it to air at no load for 12 to 24 hours, to produce a semi- finished product.

For the semi-finished product to have a leather-like appearance, additional tanning processing can be carried out which, taking the properties of the semi¬ finished product into account, comprises the following: the material, which has been exposed to air, is washed with water at 50-60°C until the pH of a section is 4.2-4.4, wrung out, treated with neutralising emulsion incorporating VNIIZh compound, acetate or sodium formate and NF dispersant at rates of 1-2, 0.5-1 and 0.4-1.2, respectively, according to the mass of the semi-finished product, wrung out, treated with a dye at 50°C at a rate of 1-5% of the mass of the semi-finished product, fat-liquored with emulsion solution with a fat content of 8-10% of the mass of semi-finished product (in terms of 100% fat), wrung out, subjected to final tanning with tanning solution containing 4-10% tanning resins, 1-5% electrolyte resistant synthetic fat, 4-10% synthetic tanning agent, 2-6% mimosa extract and 1-4% neutralising agent_/ wrung out until the moisture content is 30-40%_/ exposed to air for 12-24 hours, after which cyclic wringing out and wetting is carried out at a temperature of 50"C. The material produced by the method described above is subjected to finishing treatment. Best Mode for Carrying out the Invention

When carrying out the proposed method, at the stage when the solution made from untanned leather waste and the compound made from tanned leather waste are combined, only the particle size suggested for the compound (0.2-0.6mm) and the combining process parameters (temperature and time) suggested guarantee the uniformity required for further processing. Introduction of a cross-linking agent to the mixture makes it reactive. The range of the cross-linking agent content suggested is sufficiently wide to determine a broad range of characteristics and forms for the material produced. A very soft, delicate sponge is obtained using the lower limit quantity of cross-linking agent (0.15% by mass). The maximum amount of cross-linking agent suggested produces a denser material, from which a leather-like product can be produced later on. Selection of mixture particles (0.2-0.6 mm) is also linked to the quality of the product produced and to its external appearance.

Larger particles result in a coarse grainy material, as the homogenisation process can only be carried out for a very restricted period of time because a mass with large particles separates into layers. The mass obtained is spread on a support in a layer, the thickness of which depends on the qualities required of the end product. The following may be used as a support: a tray, endless tape, a mould. During the freezing process deep freezing is carried out to start with, during which a chemical reaction is practically nonexistent, and only ice crystals are formed. The size of the ice crystals depends on the rate at which freezing is carried out (faster freezing results in smaller crystals) . The ice crystals determine the presence of pores in the material. The size of the pores depend on the size of the crystals. The proposed freezing process was determined precisely for the mixture mentioned above. The process enables material with a wide range of porosity to be produced from the mixture. A wide range of final products can be produced from the material at a later stage. When kept in a frozen state for 4-24 hours at minus 2°C to minus 20°C a chemical reaction occurs. The speed of this reaction depends on the size of the water crystals, on the temperature, on the size of the particles of the frozen mass and on the concentration of reagents. The freezing process proposed, which was determined on the basis of the properties of the proposed mixture, ensures that the maximum possible polymerisation reaction will occur, which subsequently determines the quality of the end product.

The polymer material obtained after thawing is washed to remove the residue of unreacted matter and matter which has not penetrated the material's structure. Maintaining the material, wet, on an even surface at no load at room temperature ensures its relaxation. Subsequent heating, which removes protein which was not part of the reaction, renders the material produced capable of undergoing further tanning processing and improves the strength of the resulting material. The heating process chosen is the best one for processing using the proposed method. Washing with alkali-saline solution neutralises acetic acid remaining in the material as a result of the chemical reaction on the leather raw material at the initial processing stage. The proposed acidity limits of this solution were determined to ensure that the neutralisation process occurs at an optimal speed and to rule out a corrosive effect on the material's structure. The material undergoes hot moulding to thicken and strengthen its surface. This has an effect on the appearance and properties of the end product. After moulding the semi-finished product is exposed to air at no load for 12-24 hours. After this the material may be rolled, stored or subjected to further processing to give it a leather-like appearance. This processing uses methods which differ from conventional tanning methods in relation to the characteristics of the processable semi-finished product.

The proposed method is explained in the examples below.

Example 1

Cattle raw hide or cattle raw hide scrap obtained by contouring raw hide, is washed in running tap water for 0.5-1 hour. 20 Kg of cattle raw hide is ground with ice in a meat grinder with a grill aperture diameter of 0.16-2 mm. The ground raw material is treated at room temperature for 4 hours with a 5-10% common salt solution, washed with water, and treated with pepsin at 0.03-0.06 unit of activity/ml with a liquid coefficient of 3-4 and a temperature of 20-25°C for 2 to 3 days. The raw hide is then treated in a caustic soda solution 0.1-1.0 N for not less that 24 hours at 15-20°C, washed in running water and frozen at a temperature not less than minus 30° for not less than 1 day, and then thawed. After thawing the fibrous collagen particles are washed in running water at a temperature no higher than 20°C. The washed matter is dissolved in 100-180 litres of 0.5-1.0M acetic acid solution. The resulting solution has a pH of 2.5-4.0, an intrinsic viscosity of 10/20 dl/g, and a denaturation temperature of 35-40°C. 120Kg of tanning cuttings containing chrome are mixed with water and ground to a particle size no larger than 0.6 mm. The compound contains 1-10% dry matter.

The collagen solution and the compound are combined and homogenised at a temperature no higher than 15°C for 2-3 hours, filtered in filter presses with mesh

0.2-0.6 mm and cooled to 0-5^CC. A cross-linking agent such as glutaric aldehyde is added at a rate of 0.5- 0.75% by mass. Then the mixture is homogenised again, spread in a uniform layer 10-12 mm thick on a supporting surface and frozen at minus 60°C to minus 75^CC for 15-25 minutes. The frozen material is maintained at minus 14° to minus 16° for 6 to 8 hours. The material is thawed and exposed to air at no load for 12 hours, then heated to 85^o-105^o, cooled to room temperature, treated with an alkaline-saline solution with a pH of 9-10 for 10-20 minutes, wrung out until the residual moisture content is 30-40%, subjected to hot moulding and exposed to air at no load for 12 to 24 hours.

To give the semi-finished product a leather-like appearance, the material is placed, after is has been left to lie, on a supporting surface and subjected to dye/fat-liquoring operations in an irrigating unit, where the following operations are carried out:

^c first: treated with water 50-60°C in temperature until the pH of a section of the semi-finished product is 4.2-4.4, wrung out; ° second: treated with neutralising emulsion at a temperature of 50"C containing VNIIZh compound, acetate or sodium formate and NF dispersant, at the rate of 1-2, 0.5-1 and 0.4-1.2, respectively according to the mass of the semi-finished product, wrung out; ° third: treated with dye solution at a temperature of 50°C. Dye quantity: 1-5% of the mass of the semi-finished product; ^c fourth: treated with a fatty emulsion solution at a fat rate of 8-10% of the mass of the semi-finished product (in terms of 100% fat), wrung out; ° fifth: treated with a tanning solution, containing 4-10% tanning resins, 1-5% electrolyte resistant synthetic fat, 4-10% synthetic tanning agent, 2-6% mimosa extract, 1-4% neutralising agent, wrung out until the moisture content is 30-40%.

Then the material is left to lie for 12-24 hours and cyclic wringing out and wetting at a temperature of 50^βC and staking operations take place.

Finishing operations include impregnation, hot moulding, application of a colourless base coat, application of a coloured base coat, and application of a coating pigment and a fixing layer. After this the material is subjected to hot moulding, left to lie and stored. The material produced is 0.4-0.55 mm thick and suitable for use in the leather fancy goods industry for the manufacture of various items (bags, belts etc). It has high gas and water permeability, elasticity, and is suitable for the manufacture of various footwear elements. Example 2

Collagen solution is prepared as for example 1.

300 Kg of leather cuttings containing chrome are mixed with water and ground until the particles are 0.4-0.5 mm in size. The compound obtained has a dry matter content of 6-9%.

The collagen solution and the compound are combined and homogenised at a temperature no higher than 15°C for 3-5 hours, filtered, chilled to 0-5°C, glutaric aldehyde is added at a rate of 1.3-1.5% by mass. The mixture is homogenised, laid in an even layer, 25-28 mm thick, on a supporting surface and frozen at minus 14°C to minus 20°C for 1.7-2.0 hours. The frozen material is kept at a temperature of minus 2° to minus 7°C for 22-24 hours. Then the material is thawed, exposed to air at no load for 10-12 hours, heated to a temperature of 85-105°C, cooled to room temperature, treated with an alkaline-saline solution with a pH of 9-10 for 15-20 minutes, wrung out until the residual water content is 30-40%, subjected to hot moulding and exposed to air at no load for 22-24 hours. Then the material undergoes drying/fat-liquoring operations as in example 1. After being left to lie for 20-24 hours cyclic wringing out and wetting is carried out at a temperature of 50^βC and then final processing occurs, which comprises impregnation, hot moulding, application of a fixing layer, hot moulding and leaving the material to lie. The material produced is 3.5-5.5 mm thick, has high soundproofing properties and good heat insulation properties. Such material is suitable for domestic finishings, aeroplane cabins, car interiors and for the manufacture of footwear elements. Although this invention has been described by way of example it is to be understood that improvements and/ or modifications may be made thereto without departing from the scope of the invention as defined in the appended claims.

Industrial Applicability

The methods described above allow leather raw material waste to be used to produce leather-like material from the waste which can have a wide range of applications. The material is inexpensive to produce and does not have the basic defects found in synthetic leather-like materials, such as impermeability to air.

The methods are directly applicable to the tanning industry, but the products of the methods have a broad range of application including: in light industry in the manufacture of leather-like material for producing leather fancy foods and footwear, and for the manufacture of finishing material for use in the construction, transportation and furniture manufacturing industries.

The processes set out in the description and the invention formula, which characterise the proposed method, allow a wide range of variation in the properties of the material produced and in its appearance.

Claims

1. A method for producing a semi-finished collagen- containing material comprising the steps of

(xv) preparing a collagen solution from untanned leather waste,

(xvi) combining the collagen solution with a composition comprising tanned leather waste, (xvii) filtering the resulting homogeneous mass, (xviii) cooling the homogeneous mass, (^χi^χ) adding a cross-linking agent to the resulting mass, (xx) homogenising the resulting mixture, (xxi) freezing the resulting mixture, (xxii) thawing the frozen mixture, to obtain a polymer material,

(xxiii) exposing the polymer material to air under no load, (xxiv) heating then cooling to room temperature the resulting material, (xxv) treating the resulting material with an alkali-saline solution, (xxvi) reducing the moisture content by mechanical means, (xxvii) hot pressing, and (xxviii) further exposing the material to air under no load, to produce the semi-finished collagen-containing material.

2. A method of claim 1, in which the composition comprising tanned leather waste includes particles in the range from about 0.2 mm to about 0.6 mm in size.

3. A method of claim 1 or claim 2 in which step (ii) is carried out at a temperature of no higher than about 15°C for about 1 to about 5 hours.

4. A method of any one of claims 1-3, in which the homogeneous mass obtained in step (ii) has a pH of about 2.6 to about 5.0 and contains about 0.1 to about 2% by mass untanned collagen.

5. A method of any one of claims 1-4, in which the mass resulting from the filtering step (iii) has particles in the range from about 0.2 to about 0.6 mm in size.

6. A method of any one of claims 1-5, in which the mass is cooled in step (iv) to a temperature between about 0 and about 5°C.

7. A method of any one of claims 1-6 in which the crossing linking agent added in step (v) is added at a rate of 0.15 to 7.0% by mass.

8. A method of any one of claims 1-7, in which the homogenising step (vi) is carried out at a temperature no higher than about 5°C.

9. A method of any one of the preceding claims 1-8, in which the freezing step (vii) is carried out

a) at a temperature between about minus 14°C to about minus 75°C for up to about 2 hours, then b) at a temperature between about minus 2°C to about minus 20°C for about 4 hours to about 24 hours.

10. A method of any one of the preceding claims 1-9, in which the exposure step (ix) is carried out for about 6 to about 12 hours.

11. A method of any one of the preceding claims 1-10, in which the heating of step (x) is to a temperature of from about 85°C to about 105°C, for a period of up to about 1 hour.

12. A method of any one of the preceding claims 1-11, in which the alkali-saline solution used in treatment step (xi) has a pH in the range of from about 9 to about 10.

13. A method of any one of the preceding claims 1-12 in which the treatment step (xi) is carried out for about 10 to about 20 minutes.

14. A method of any one of the preceding claims 1-13, in which the moisture content is reduced in step (xii) to about 30% to about 40%.

15. A method of any one of the preceding claims 1-14 in which the exposure of step (xiv) is for about 12 to about 24 hours.

16. A method for producing semi-finished product for the manufacture of collagen-containing materials, in which a mass, containing broken up collagen and partially separated collagen free proteins, is produced from leather raw material by means of machining and chemical processing, is frozen, and after thawing undergoes final processing to produce semi-finished product for future use, this method comprising: preparing a collagen solution from untanned leather waste, combining the collagen solution with a compound prepared from tanned leather waste with solid matter particles of 0.2 to 0.6 mm in size for 1 to 5 hours at a temperature no higher than 15°C to obtain a homogeneous mass containing 0.1 to 2% by mass untanned collagen and 0.3 to 10% by mass tanned collagen, and having a pH of 2.6 to 5.0, - filtering the mass until its particles are 0.2 to 0.6 mm_/ cooling the mass to 0 to 5^βC, adding a cross-linking agent to the mass at a rate of 0.15 to 7.0% by mass, to produce a mixture, - homogenising the mixture at a temperature no higher than 5°C, - freezing the homogenised mixture at minus 14°C to minus 75°C for 0.1-2.0 hours, and then at minus 2°C to minus 20°C for 4 to 24 hours, - thawing the mixture to obtain a polymer material, processing the polymer material by exposing it to air at room temperature, wet, at no load, for 6 to 12 hours, heating it to 85^βC to 105°C, cooling it to room temperature, treating it with an alkali- saline solution with a pH of 9 to 10 for 10 to 20 minutes and wringing it out until the residual moisture content is 30 to 40%, hot pressing the polymer material and further exposing it to air at no load for 12 to 24 hours, to produce a semi- finished product.

17. The method of claim 1 further comprising the steps, after exposing the semi-finished product to air, of: washing the semi-finished product in water at a temperature of 50 to 60^CC until the pH of a section is 4.2 to 4.4, wringing the product out before treating it at a temperature of 50°C with neutralising emulsion containing VNIIZh compound, acetate or sodium formate and NF dispersant at the rates of 1-2%, 0.5-1.0% and 0.4-1.2% of the mass of the semi-finished product respectively,

- wringing the product out again before treating it at 50°C with dye at a rate of 1- 5% of the mass of the semi-finished product, fat-liquoring the product with an emulsion solution with a fat content of 8 to 10% of the mass of semi-finished product (in terms of 100% fat), wringing the product out again, tanning with tanning agent solution containing 4-10% tanning resins, 1-5% electrolyte resistant synthetic fat, 4-10% synthetic tanning agent, 2.0-6.0% mimosa extract and 1.0-4.0% neutralising agent,

- wringing out until the moisture content is 30-40%, exposing the material to air for 12 to 24 hours, and cyclic wringing out and wetting at a temperature of 50^βC.