Bleaching and dyeing; fluid treatment and chemical modification – Treatment of hides – skins – feathers and animal tissues – Tanning
Patent
1994-06-27
1995-06-20
Willis, Jr., Prince
Bleaching and dyeing; fluid treatment and chemical modification
Treatment of hides, skins, feathers and animal tissues
Tanning
8 9421, 8 9422, 8 9418, 252 857, C14C 322
Patent
active
054257840
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EP93/00061 filed Jan. 14, 1993.
The present invention relates to the use of water-soluble graft polymers which are obtainable by polymerizing acrylic acid or methacrylic acid, if required with further monomers, in the presence of monosaccharides, oligosaccharides, polysaccharides or derivatives thereof, as tanning agents in leather and skin production.
In leather production, the main tanning is usually carried out using mineral tanning agents, such as basic chromium, aluminum and/or zirconium salts alone or in combination with synthetic tanning agents. Subsequent retanning with natural or synthetic tanning agents serves to improve the leather properties, such as handle, softness, grain characteristics and body. For example, syntans, ie. water-soluble condensates of, for example, naphthalenesulfonic acid and formaldehyde or of phenolsulfonic acid, formaldehyde and urea, as well as ligninsulfonic acids and polymers and copolymers based on acrylic acid and other unsaturated polymerizable carboxylic acids, as a rule in combination with the above-mentioned syntans, are used as tanning agents for retanning.
For example, U.S. Pat. No. 2,205,882 (1) and U.S. Pat. No. 2,205,883 (2) describe the use of polyacrylic acid, of copolymers of acrylic and methacrylic acid, of styrene/maleic anhydride copolymers, of polymethacrylic acid, partially hydrolyzed polymethyl methacrylate and of copolymers of methacrylic acid with styrene or methyl methacrylate for tanning leather. The disadvantages of these products are that they generally considerably lighten the color and, when too large an amount is used, lead to a rubber-like handle of the leather.
For the production of leather and skins having a fine grain and uniform color, GB-A 2 074 173 (3) and GB-A 2 137 654 (4) describe terpolymers consisting of nitrogen-containing (meth)acrylates, (meth)acrylates and small amounts of (meth)acrylic acid as tanning agents. In order to reduce the tack, it may also be grafted onto water-soluble proteins or polysaccharides.
EP-A 441 197 (5) discloses graft copolymers of monosaccharides, oligosaccharides, polysaccharides and modified polysaccharides with monomer mixtures of monoethylenically unsaturated carboxylic acids or their anhydrides and, if appropriate, further ethylenically unsaturated monomers. These graft copolymers are recommended as additives for detergents.
Chem. Abstr. 94 (1981) (6), 192926s describes water-absorbing graft copolymers of polysaccharides and acrylic acid or acrylic acid derivatives.
Journal of the American Leather Chemists Association 85 (1990) (7), 425-430 recommends a novel acrylic acid syntan as a retanning agent for chrome leather. This syntan is prepared by graft polymerization of acrylic acid and methacrylic acid onto a mixture of sulfated fish oil and alginic acid.
The stated prior art agents have a number of disadvantages. In particular, they lighten the color of the leathers and skins thus produced to an excessive extent. Moreover, they lead to poor lightfastness and heat resistance. They may also impart an undesirable rubber-like handle to the leather.
It is an object of the present invention to provide the leather industry with tanning agents for leather and skin production which no longer have the stated disadvantages.
We have found that this object is achieved by the use of water-soluble graft polymers of monosaccharides, oligosaccharides, polysaccharides and derivatives thereof, obtainable by free radical polymerization of mixture thereof or of the alkali metal, alkaline earth metal or ammonium salts thereof, which are copolymerizable with the monomers (a) and unsaturated, nonconjugated double bonds in the molecule, hydrolyrically or enzymatically degraded polysaccharides, oxidized hydrolyrically degraded or oxidized enzymatically degraded polysaccharides, chemically modified mono-, oligo- or polysaccharides or mixtures of the stated compounds in a weight ratio A:B of from 95:5 to 20:80, as tanning agents for the self-taming, pretanning and simultaneous tanning of pe
REFERENCES:
patent: 5227446 (1993-07-01), Denzinger et al.
Denzinger Walter
Hartmann Heinrich
Wegner Brigitte
BASF - Aktiengesellschaft
Diamond Alan D.
Willis Jr. Prince
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