The method of tanning leather

 

(57) Abstract:

The method can be used in the manufacture of leather mineral tanning. After pickling pickling takes place simultaneously tanning chrome tanning agent and neutralizing the alkaline agent in one step. As the alkaline agent, a mixture of sodium bicarbonate with urea resin in a ratio of 85 : 15 to 88 : 12%. From this mixture previously prepared tablets weight 1 - 2, Dried at a temperature of 50 - 70oWith and cover the nitrocellulose in the amount of 1.0 to 1.5% by weight of the dry tablet. Again dried at the same temperature. There is continuity and simplifying the process and saving tanning materials and improve the quality of the leather.

The invention relates to a method tanned natural leather and can be used in the manufacture of leather mineral tanning care.

There is a method of tanning leather, including pickling, tanning dry chrome tanning agent basicity 36-42% with a flow rate of 2.2 - 2.5% by weight of the hide (in terms of Cr2O3) and neutralization with sodium bicarbonate. Moreover, the catalyst is injected through 3 - 4 hours from start tanning (Progresa of the hide) 2-3 times with idinas neutralization is 10-12 hours (Handbook of Tanner. Technology./Ed. by N. A. Babirovoy.- M: Legprombytizdat 1986, S. 11, 12, 21-25].

The disadvantage of this method of tanning is the need for repeated adjustment and control of the basicity of the solution in the process of tanning, pause while mechanical devices, with which the process of tanning, which leads to increase the length and complication of the process of tanning.

The proposed method of tanning leather runs continuously and provides the simplification of this process through the use of samopodderzhaniya of tannins, savings tanning materials and quality leather.

This is achieved in that in the method of tanning leather, involving the processes of pickling pickling, tanning dry chrome tanning agent and neutralizing the alkaline agent, as the alkaline agent, a mixture of sodium bicarbonate with urea resin (ISF) in 85:15 ratio of 88: 12%. From the resulting homogeneous mixture is prepared tablets weighing 1 to 2 grams dried at a temperature of 50 - 70oC and covered with nitrocellulose in an amount of 1.0 to 1.5% (by weight of the dry tablet), again dried at the same temperature and injected simultaneously rija and urea resin is enveloping grains of sodium bicarbonate polymer film, which upon contact with an aqueous medium tanning solution swells and gradually dissolves, and protects for a while sodium bicarbonate from contact with the aqueous medium, providing a quick paint over of the hide slightly basic compounds of chromium (III). Coated tablets with nitrocellulose slows down the process of dissolution of the alkaline agent, as the dissolution of the film takes place gradually and unevenly distributed within the coverage area of the tablet, thereby reducing the active surface of the alkaline agent and, accordingly, the rate of dissolution and thereby provides a more gradual increase in the basicity of the tanning solution of chromium (III).

The use of alkaline agent in this form allows in one step to enter the tanning and neutralizing substances, eliminate the control and adjustment of the basicity of tanning solutions and thereby to simplify and accelerate the tanning process, to save the consumption of scarce tanning agent and to improve the quality of the skin due to the smooth flow of diffusion of the tanning agent into the dermis and to more evenly distribute it in the leather material.

The gradual increase of basicity tanning complexes of chromium (III) in the process of choreopathy with the introduction of the tanning agent and the school is further, deposited at the protein elements of the structure of collagen, providing high quality tanned skin, and eliminate technological marriage as "tadoba".

The essence of the proposed method of tanning leather is the hide, obtained by standard methods from raw materials of bovine animals, subjected to pickling. After pickling the drums enter at the same time the tanning agent and alkaline agent. As the alkaline agent, a mixture of sodium bicarbonate with urea resins, which are pre-mixed in the ratio of 85:15 to 88:12% and the resulting homogeneous mixture is prepared tablets weighing 1-2, the Tablets are dried to constant weight at a temperature of 50-70oC, covered with a layer of nitrocellulose in an amount of 1.0 to 1.5% (by weight of the dry tablet) and again dried at the same temperature. Tanning conduct dry chrome tanning agent for 6-8 hours when liquid ratio LCD 0,8-1 and a temperature of 20-25oC.

The effect of alkalizing means starts after 2.5-3 hours, dissolve after a specified time period of not less than 1.5 hours, which confirms quasirandomly the process of forming the sizes of tanning packages and certificates regulated and managed process control is injected into the drum at the same time 0,230 kg (2,3% by weight of the hide, counting on Cr2O3dry chrome tanning agent basicity 38% 0,070 kg (0,07% by weight of the hide) alkaline agent. The alkaline agent is a mixture of sodium bicarbonate and urea resin in a ratio of 85: 15%. From this mixture produced tablets weighing 1 g each, were dried at a temperature of 50oC, to constant weight, was coated with nitrocellulose as a protective layer -1% by weight of the dry tablet. The hide was treated for 7 hours with the LCD of 0.8 at a temperature of 23oC.

Temperature welding of leather prefabricated determined after aging, reached 111oC, the limit of its tensile strength was 31 MPa, the content of chromium oxide in the waste liquid - 1.8 g/DM3while the control sample made by the standard method, providing 12-hour tanning of the hide, had a temperature of welding 106oC and the tensile strength of the skin tensile - 22 MPa, the content of chromium oxide in the treated liquid - 7-8 g/DM3.

Example 2. The method was carried out analogously to example 1 with Golem bull. The alkaline agent is taken in the ratio of sodium bicarbonate and ISF 88:12%, a protective layer of nitrocellulose to 1.5% by weight of the dry tablet. Drying tablets separator welding leather semi-finished product in this case has reached 111oC, the tensile strength of leather prefabricated tensile amounted to 315 MPa, the content of chromium oxide in the waste liquid - 1.7 g/DM3.

Example 3. The method was carried out analogously to example 1 with Golem bull. The alkaline agent in the ratio of sodium bicarbonate and ISF 90:10%, a protective layer of nitrocellulose a-0.7% by weight of the dry tablet. Drying tablet neutralizer mass of 0.7 g was carried out at a temperature of 45oC. Tanning was carried out for 8 h

The temperature of the welding leather semi-finished product in this case has reached 92oC, the tensile strength of the skin under tension was 20 MPa, and the content of chromium oxide in the waste liquid to 5.8 g/DM3.

Example 4. The method was carried out analogously to example 1 from bull hide. The alkaline agent is taken in the ratio of 80:20% of sodium bicarbonate and ISF, a protective layer of nitrocellulose -1,8% by weight of the dry tablet. Tablet alkaline agent by weight of 2.5 g was dried at a temperature of 75oC. Tanning was carried out for 7 hours

The temperature of the welding leather semi-finished product in this case has reached 110oC, the tensile strength of the skin when stretching was 28 MPa, the content of chromium oxide in the waste liquid is 38 g/DM3.

So, by reducing the content of ISF and nitrocellulose in the tablet, as well as the mass of the tablet and its drying temperature below the permissible (protected) is the deterioration of the output parameters of leather belts. Weight reduction tablets at the same total quantity of alkaline agent leads to an increase in the surface of the tablets, which affects the speed of increasing the basicity of the solution. Lowering the temperature of the drying tablets compared to the protected temperature interval leads to insufficient film strength during formation of the protective layer tabletsevista process Progresa of the hide.

Excess content ISF and nitrocellulose in the tablet, as well as the increase of drying temperature and mass of the tablet alkaline agent above the protected values results in excessive tanning composition and deterioration of the output parameters by increasing the duration of the process choreopathy. In addition, high temperature drying contributes to the cracking of the surface protective film and the faster water penetration into the tablet and its rapid dissolution. When increasing the size of the tablets above the allowed value increases the mechanical tension in the mass of the tablet in contact with her goliam substance in the tanning drum, which leads to loss of strength tablets and more rapid dissolution. All this contributes to premature increase in the basicity of the tanning solution, slows down the process of Progresa hide tanning with chromium compounds (III) and, accordingly, the quality of the skin.

The method of tanning leather, including the processes of pickling pickling, tanning, chrome tanning agent, neutralizing the alkaline agent, wherein as the alkaline agent, a mixture of sodium bicarbonate with urea resin in a ratio of 8 is covered with nitrocellulose in an amount of 1.0 to 1.5% of the dry weight of the tablet, again dried at the same temperature and injected simultaneously with the tanning agent in one step.

 

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SUBSTANCE: method comprises pickling, tanning, and neutralizing the semifinished item. During pickling and subsequent tanning, the picking liquid is provided with acetate sodium in amount of 0.2-0.5 % and, then, chromic tanner in amount of 1.5-1.8%. The tanning is carried out until the pH of the solution reaches 4.2-4.4.

EFFECT: enhanced quality of tanning.

2 tbl

FIELD: leather industry.

SUBSTANCE: method involves pickling leather depilated hide with sodium chloride and sulfuric acid, addition of chrome tanning agent to the same bath in its consumption 0.5-0.6% of depilated hide mass as measured for chrome oxide, and chrome-plating is carried out for 2-4 h. Aliphatic dialdehyde is added to same bath in the concentration 3-6% of depilated hide mass, and treatment is carried out for 2-3 h wherein glyoxal or glutaraldehyde is used as dialdehyde. Invention provides enhancing thermal stability and strength properties of leather and can be used in tanning leathers for different designation and assortment.

EFFECT: improved tanning method.

2 cl, 1 tbl, 9 ex

FIELD: chemistry, hide tanning.

SUBSTANCE: method relates to tanning hides and can be used in the leather industry. Animal hides are treated with a solution of chrome tanning agent with addition of an activating organic agent in form of aminocapronic acid at concentration of 8-12 g/l.

EFFECT: improved strength properties of hides and environmentally safe method.

5 ex

FIELD: process engineering, leather industry.

SUBSTANCE: after hide pickling, skins are sent to ageing. Then fur leather layer is processed by priming solution comprising chrome tanning agent with concentration of 9-18 g/l per chrome oxide. Skins are aged to effect main paste-tanning-stuffing and ageing.

EFFECT: improved organoleptic properties of fur skins, ie broach, softness, elasticity and higher tensile strength.

2 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: method involves chrome tanning and post-tanning a semi-finished product through chrome tanning in the presence of a product of reaction of 3-aminopropyltriethoxysilane and glycidylmethacrylate in molar ratio of 1:2 and consumption of the chrome tanning agent and reaction product of 3-4% and 2-3% of the weight of the semi-finished product respectively. Neutralisation and hydrophobisation with a polymer tanning agent are then carried out for 30-40 minutes with consumption of the tanning agent equal to 8-10% of the weight of the semi-finished product. After that dyeing is carried out in the presence of a synthetic tanning agent in amount of 3-4% of the weight of the semi-finished product. Post-tanning is carried out with a plant-material tanning agent and the semi-finished product is also treated for 20-30 minutes with a product of reacting hexamethylenediamine with phosphoric acid and urea in the presence of glycerin in molar ratio of 1:3:3:0.5 respectively, in amount of 3-4% of the weight of the semi-finished product and for 20-30 minutes with organic acid in amount of 0.5-1.0% of the weight of the semi-finished product. Further, the semi-finished product undergoes greasing and re-treated for 40-50 minutes with a product of reacting hexamethylenediamine with phosphoric acid and urea in the presence of glycerin in molar ratio of 1:3:3:0.5 and consumption of 7-8% of the weight of the semi-finished product, volume ratio of 0.8-1.0 and temperature of 20-22°C. Hydrophobisation with a polymer tanning agent, dyeing in the presence of a synthetic tanning agent, post-tanning with a plant-material tanning agent, further treatment with a product of reacting hexamethylenediamine with phoshoric acid and urea in the presence of glycerin in the said molar ratio and with organic acid is carried out in one bath. Separation and drying are carried out after all operations.

EFFECT: higher water-, fungus- and heat-resistance of leather under high moisture and temperature conditions, and wide range of special types of leather.

2 cl, 3 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: invention refers to general chemical engineering and is applicable to measure a mass transfer rate of various materials into capillary-porous bodies of leather and fur industries, wood processing, construction materials manufacturing, textile industry, etc. The method consists in the fact that capillary-porous body samples, e.g. leather, are filled with chemicals; this process involves sectioning specimens to be analysed to a chemical penetration speed as shown by a penetration depth per a unit of time. The capillary-porous bodies, e.g. thickness leather specimens are fixed in a retainer of a contrast colour, placed on a surface of a contrast colour and recorded by means of a remote digital camera fixed on a Tripod. The digital camera is provided with extension rings for macrophotography and a ring flash; a sample image is uploaded into a software programme for digital processing of colour images to generate a chemical penetration histogram into the thickness of the capillary-porous body, which is used to measure an area of the stained specimen, whereas a speed is calculated by the area of the stained specimen per a unit of time.

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29 dwg, 6 tbl

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SUBSTANCE: weathered vitrinite brown coals from Baga-Nursk coal field having ash level 36-48% and moisture 20% are ground to granule size 0.5-0.9 mm. Resulting powder us sulfurized for 6-8 h with 98% sulfuric acid at 60-80°С and coal-to-acid weight ratio from 1:3 to 2:3. Sulfurized coal is neutralized and treated with 10-15% sodium hydroxide aqueous solution at weight ratio of alkali solution to initial coal (10-15):1 to form water-soluble sodium sulfohumate, after which water-soluble residual coal is separated by centrifugation. Centrifugate is mixed with 10-15% aqueous hydrochloric acid at volume ratio (10-15):6 to form precipitate, which is allowed to settle into compact form during 40-60 min. After decantation of liquid phase, solid residue is partially dried at 40-60°С until pasty mass is obtained.

EFFECT: increased content of tanning substances in humate-containing compounds and enabled utilization of oxidized brown coal in open-cut production of brown coals.

4 tbl, 5 ex

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