Coating processes – With post-treatment of coating or coating material – Heating or drying
Reexamination Certificate
1998-11-09
2001-03-13
Wilson, Donald R. (Department: 1713)
Coating processes
With post-treatment of coating or coating material
Heating or drying
C428S433000, C252S008570, C008S094330, C008S094260, C008S09410R, C008S094110, C008S094210, C524S549000, C524S555000, C524S556000, C525S327800, C526S318500
Reexamination Certificate
active
06200640
ABSTRACT:
The present invention relates to the use of aqueous solutions or dispersions of copolymers based on ethylenically unsaturated dicarboxylic acids or dicarboxylic anhydrides, lower olefins and hydrophobic comonomers for retanning, fat-liquoring or hydrophobicizing leather and fur skins, and to some of the copolymers used, process for their preparation and leather treatment composition comprising these copolymers.
DE-C 2 629 748 discloses the use of copolymers of linear C
10
- to C
30
-olefins and maleic anhydride which have been hydrolyzed by means of alkali metal bases or amines for filling and fat-liquoring leather and fur skins.
EP-A-0 412 389 discloses the use of aqueous solutions or dispersions of partially neutralized copolymers of maleic anhydride with C
8
- to C
40
-olefins and their polymer-analogous reaction products for hydrophobicizing leather and fur skins. Examples of olefin components which are mentioned are 1-octene, diisobutene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene and cyclooctene. Polymerization is carried our in substance.
EP-B-0 486 608 discloses the use of copolymers based on maleic anhydride, octadecyl vinyl ether and, if appropriate, n-1-octadecene for hydrophobicizing leather and fur skins.
EP-A-0 579 267, EP-A-0 581 327, EP-A-0 372 746 and EP-A-0 498 634 describe amphiphilic copolymers comprising a greater proportion by weight of a hydrophobic comonomer and a lesser proportion by weight of a hydrophilic comonomer, and their use for treating leather.
The copolymers used in accordance with EP-A-0 581 327 and EP-A-0 498 634 as retanning fat-liquoring agents for the production of leather having improved fogging properties for use in automobiles are preferably prepared by emulsion polymerization. However, dispersions prepared in this way contain certain amounts of surfactants. This is disadvantageous in the treatment of leather with these agents, since they increase the water wettability, making production of water-repellent leather more difficult.
DE-A-4 334 796 discloses products of the esterification of terpolymers of maleic anhydride, diisobutene and styrene, certain styrene derivatives, vinyl acetate, allyl acetate, isobutyl vinyl ether, allyl alcohol or methallyl alcohol with fatty alcohols as retanning materials for leather.
The German Patent Application having the file reference 196 08 044.4 having the title “Use of hydrophobicized copolymers of monoethylenically unsaturated dicarboxylic acids and olefins having 2 to 8 carbon atoms in detergents and cleaning materials”, which has an earlier priority date, but was not published before the priority date of the present application, describes terpolymers of isobutene, maleic anhydride and a C
20-24
-olefin which have been neutralized using sodium hydroxide solution. The C
20-24
-olefin can also be replaced by 1-octadecene. The polymers are used as an additive to detergents and cleaning materials. Reference is made in general form to copolymers comprising monoethylenically unsaturated dicarboxylic acids, their anhydrides or alkali metal and/or ammonium salts, olefins having 3 to 8 carbon atoms, olefins having 10 to 150 carbon atoms and other comonomers.
The polymers known for retanning, fat-liquoring and in particular hydrophobicizing leather frequentiy have the disadvantage of only penetrating into superficial layers of the flesh or hair side of the leather, so that hydrophobicization of the entire leather cross section is not achieved. In addition, the dyeability and hand of the leather are frequently impaired.
Furthermore, the known dispersions developed for retanning, fat-liquoring or hydrophobicizing frequently tend to coagulate or thicken on storage. These changes as a consequence of storage further impair the penetration behavior of these productions.
Commercially available polymeric retanning materials are often hydrophilic and are little suited to the hydrophobicization of leather. On the other hand, polymeric hydrophobicizing agents likewise have retanning, filling properties, but are not always distributed well over the leather cross section. Different results are achieved depending on the previous history of the wet-blue (=intermediate in the production of leather which is traded worldwide and comes between the skin and the finished leather during processing) employed. Since wet-blues are nowadays in many cases purchased from various sources and therefore have different pious histories, the tanner does not achieve uniform results in his production.
It is an object of the present invention to provide suitable hydrophobic, polymer-based retanning materials which enable good penetration through the leather cross section and support the hydrophobicization and/or fat-liquoring. They are intended to overcome disadvantages of the known retanning materials.
We have found that this object is achieved by using aqueous solutions or dispersions of copolymers obtainable by free-radical copolymerization of
(a) from 20 to 90% by weight of at least one monoethylenically unsated C
4-6
-dicarboxylic acid or the anhydride thereof, as component A,
(b) from 5 to 50% by weight of at least one olefin having 2 to 6 carbon atoms, as component B,
(c) from 5 to 50% by weight of at least one hydrophobic comonomer from the group consisting of long-chain olefins, esters of long-chain alcohols with acrylic acid or methacrylic acid, long-chain amides of acrylic acid or methacrylic acid, and long-chain alkyl vinyl ethers, as component C,
(d) from 0 to 40% by weight of further comonomers which can be copolymerized with the above monomers, as component D,
where the sum of the amounts of components A, B, C and, if used, D is 100% by weight,
followed by at least partial esterification or hydrolysis and neutralization and/or reaction of the carboxyl groups formed during the hydrolysis with bases, for treating leather and/or fur skins.
The object is also achieved by the provision of a copolymer obtainable by free-radical copolymerization of
(a) from 20 to 89% by weight of at least one monoethylenically unsaturated C
4-6
-dicarboxylic acid or the anhydride thereof, as component A.
(b) from 5 to 50% by weight of at least one olefin having 2 to 6 carbon atoms, as component B,
(c) from 5 to 50% by weight of at least one hydrophobic comonomer from the group consisting of long-chain olefins, esters of long-chain alcohols with acrylic acid or methacrylic acid, long-chain amides of acrylic acid or methacrylic acid, and long-chain alkyl vinyl ethers, as component C,
(d) from 1 to 15% by weight of further comonomers which can be copolymerized with the above monomers, as component D,
where the sum of the amounts of components A, B, C and D is 100% by weight, followed, if desired, by at least partial esterification or hydrolysis and neutralization and/or reaction of the carboxyl groups formed during the hydrolysis with bases.
It has been found that the polymers used in accordance with the invention satisfy both requirement: good product distribution over the leather cross section and an action which is not disadvantageous, but instead is supportive of the hydrophobicization of the leather.
The present invention provides, in particular, the use of aqueous solutions or dispersions of these copolymers as agents for retanning, fat-liquoring or these hydrophobicizing leather and/or fur skins.
However, the anhydride groups present in the copolymer can also be partially or fully solvolyzed using hydroxyl-functional compounds or amines. Examples thereof are mono-, di- or triethanolamine, morpholine and sarcosine. Any anhydride groups remaining are subjected to aqueous hydrolysis. The carboxyl groups remaining are preferably at least partially neutralized using bases. Examples of bases which can be employed are alkali and alkaline earth metal hydroxides, alkali and alkaline earth metal carbonates, ammonia and amines.
The copolymers described are used as retanning materials which provide the leather with good filling, dye penetration and a pleasant hand. In addition, they improve the distribution of the hydrophobicizing agent or fat-
Danisch Peter
Kistenmacher Axel
Kneip Michael
Wolf Gerhard
BASF - Aktiengesellschaft
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Wilson Donald R.
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