Classifications

• • C—CHEMISTRY; METALLURGY
  • C14—SKINS; HIDES; PELTS; LEATHER
  • C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
  • C14C3/00—Tanning; Compositions for tanning
  • C14C3/02—Chemical tanning
  • C14C3/08—Chemical tanning by organic agents

Definitions

• chrome tanning a relatively small proportion is vegetable tanned.
• Chrome-tanned leather shows a light blue to blue-green color, while vegetable-tanned leather is colored beige to brown.
• pure white, light-resistant leathers are mainly produced by tanning with synthetic white tanning agents, the tanning effect of which is based on phenolic hydrooxy groups, similar to the vegetable tanning agents. These white tanning agents are used as retanning agents for chrome tanning, so that such leathers are in principle chrome leathers.
• Other white tannins e.g. based on zircon and aluminum, are of little importance in practice.
• Aluminum tanning agents have recently been used for reversible pretanning, so that after leveling and trimming the rawhide, only the later finished leather substance has to be tanned chrome.
• Chrome-tanned leathers are known to have been discredited in terms of disposal recently.
• the heavy metal pollution of wastewater from chrome leather factories is also an ecological problem according to the current state of the art.
• US Pat. No. 2,992,879 describes a process for producing light leather by tanning with tetrakis (hydroxymethyl) phosphonium chloride and phenols. Leather produced in this way has a clear smell of phosphine and the phenols used, which indicates very unstable binding relationships.
• US Pat. No. 2,993,744 describes a tanning process for producing white leather, in which reaction products of tetrakis (hydroxymethyl) phosphonium chloride with amylamines, diethanolamine or melamine are used as tanning agents. These leathers also have considerable disadvantages. Even after repeated rinsing, amine smell is clearly noticeable. In addition, after multiple extraction with water, considerable amounts of tris (hydroxymethyl) phosphine oxide can be detected in it.
• the invention therefore relates to tanning processes for the production of light leather, and leather thus produced, characterized by a content of two types of ⁇ -aminoalkylphosphine groups which are obtained by the procedure described above.
• the phosphonium chloride (HOCH 2 ) 4 PCl forms a phosphine oxide structure
• impregnation is carried out according to the invention only at a low pH, so that the hydroxyalkylphosphonium compound can penetrate unchanged together with the amine salts into the skin.
• the pH increase then brings about the crosslinking between amino groups of the collagen and additionally introduced amino groups via the phosphorus compound.
• All salts such as the chlorides, sulfates, phosphates, formates, oxalates, and acetates, such as are obtained by reacting phosphine, methyl, ethyl, phenyl, tolylphosphine and diphosphino-methane, - ethane are suitable as phosphonium compounds , -methylethane, -propane, -butane, -pentane and -hexane in a known manner in the presence of the corresponding acids or from the respective phosphonium hydroxides with the desired acids and their mixtures.
• Aldehydes suitable for the production of the phosphonium compounds used are: formaldehyde, acetaldehyde, benzaldehyde, phthalodialdehydes, dialdehyde starches and preferably glyoxalal, methylglyoxal, succinic, glutaric and sebacic dialdehyde and mixtures thereof.
• Hydroxyalkylphosphonium compounds which are obtained in a conventional manner by reaction of dialdehydes or mixtures of dialdehydes and formaldehyde with the above-mentioned phosphanes in the presence of the respective acid are particularly suitable for producing the claimed leather.
• Suitable nitrogen compounds are urea, its methyl and methylol derivatives, dicyandiamide, methylol melamine and methylol guanamine, amino carboxylic acids and neutral salts of primary amines such as the chlorides, sulfates, phosphates, formates, acetates and oxalates of methylamine, Ethylamine, ethylene diamine, diethylene triamine, propylene diamine, ethanolamine, aniline, toluylamine and guanidine.
• the phosphonium compounds are used in amounts of 0.5-15%, preferably 1-6%, the nitrogen compounds in amounts of 0.1-2% based on the pimple size.
• the tanning process is carried out at normal temperatures. Since no bonds are made during the diffusion phase, the process temperature can be raised to accelerate the diffusion. Manageable liquor temperatures up to 35 ° C are useful. In view of the shrinking temperature of the native skin at approx. 50 ° C, the temperature of 35 ° C should not be exceeded.
• the liquor temperature can be reduced due to the formation of leather, i.e. with increasing the shrinking temperature, but should be checked for the usefulness of the agents used on a case by case basis.
• a reaction in the outer layers could hinder the penetration of the agents into the skin and thus the reaction; Temperature and reaction contain dependencies in this regard.
• Leather manufactured according to the application has shrinking temperatures above 90 ° C.
• the tanning process according to the invention is also suitable for the treatment of furs and skins, that is to say for skins which have not yet been subjected to a liming, the use of the process according to the invention preferably giving light hair and wool lightfast white without damage. So there is no yellowing of the wool, e.g. with glutardialdehyde tanning.
• the starting material for the tanning process described is bovine pickle bare, which was produced according to known technology documents. The amounts used are calculated on the mass of the drained pimples. Continuous processes relate the amount used to the bulk.
• the impregnation liquor is mixed from 100% pickle liquor and 100% water. 4.3% THP chloride or 4.8% THP sulfate, as 50% solutions, 10% sodium sulfate and 1% ammonium chloride, are dissolved in this liquor.
• the nakedness is processed in this fleet.
• the liquor temperature is raised to 26 ° C at the start of the process. After 90 minutes, the pH is determined, which should be around 4.7. At lower pH it is raised to 4.7 by adding sodium acetate.
• the impregnation of the nakedness with the phosphonium compound is followed by the conditioning. This is done by treating the nakedness in 10% of the weight of water, to which 1% of the weight of ammonia is added. This makes the pH of the fleet including the nakedness raised. It should then be 6.5, so it should still be acidic.
• the process temperature is kept at 26 ° C.
• the desired tanning is carried out again with 10% water and 1% ammonia. This raises the pH further and should be 7.7 after 90 minutes and 8.2 after another 120 minutes.
• After the total running time of 3.5 hours at 26 ° C a rest phase of up to 24 hours in the vascular system is possible without wrinkles becoming stuck.
• the wet dressing can be carried out in the manner customary in wet blue processes.
• the shrinkage temperature of the material thus obtained was 91 ° C.
• Example 2 The procedure was the same as in Example 1. However, the reaction product obtained from glutardialdehyde, formaldehyde and phosphane in a molar ratio of 1: 2: 1 and the presence of hydrochloric acid was used as the phosphonium compound in an amount of 2.5% together with 0.8% ammonium sulfate used.
• the leather obtained showed a shrinking temperature of 94 ° C.
• Example 2 The procedure was the same as in Example 2.
• the reaction product of glyoxal, formaldehyde and phosphane in a molar ratio of 1: 2: 1 was used as the phosphonium compound in the presence of hydrochloric acid.
• a solution of 2% glycine and 5% sodium sulfate was used as the nitrogen component.
• a 2% potassium carbonate solution was used to raise the pH.
• the impregnation liquor was prepared using 3.5% tris (hydroxymethyl) methylphosphonium chloride and 1% ammonium sulfate.
• the leather obtained showed a shrinking temperature of 91 ° C.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Treatment And Processing Of Natural Fur Or Leather (AREA)

Applications Claiming Priority (2)

Publications (1)

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Cited By (7)

Citations (4)

• 1996
  • 1996-05-25 DE DE1996121219 patent/DE19621219A1/de not_active Withdrawn
• 1997
  • 1997-05-22 EP EP97108292A patent/EP0808908A1/fr not_active Withdrawn

Patent Citations (4)

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