Use of carboxyamide-polysiloxanes for water proofing leather

Details Use of carboxyamide-polysiloxanes for water proofing leather Use of carboxyamide-polysiloxanes for water proofing leather

1999-07-16

2000-08-29

Einsmann, Margaret

Bleaching and dyeing; fluid treatment and chemical modification

Treatment of hides, skins, feathers and animal tissues

Fur

8 9418, 8 9423, 8 941R, C14C 900

Patent

active

06110230&

DESCRIPTION:

BRIEF SUMMARY
The invention relates to the use of carboxyamide-polysiloxanes of the formula IV ##STR3## in which R, R' and R", each independently, are selected from C.sub.1-6 -alkyl or phenyl, or carboxyamide-polysiloxanes of the formula IVa ##STR4## wherein R' and R", each independently, are selected from C.sub.1-6 -alkyl, C.sub.1-6 -alkoxy, OH or phenyl, and the number of types of structural units defined by ##STR5## is at least one and a is selected from the range 0.ltoreq.a.ltoreq.2 and b is selected from the range 1.ltoreq.b.ltoreq.3, and the number of repetitions of the types of structural units which is defined by the variables m, n and k is selected from the ranges ##STR6## in which p=0-10 and Y and Z, each independently, are a divalent hydrocarbon radical from the group of aliphatic hydrocarbons or are a divalent alkoxyalkyl radical, and where 2.ltoreq.y.ltoreq.6, C.sub.1-20 -alkyl or C.sub.2-20 -alkenyl --CH.dbd.CH--, cyclic or bicyclic, saturated or unsaturated hydrocarbons or the aromatic hydrocarbons, where optionally some of the substituents B are replaced by the substituents A of the following formula II ##STR7## in which Y, p and Z are as defined above, or by the substituents C of the following formula VII ##STR8## in which p'+p"=p and X, Y and Z are as defined above, the carboxyamide-polysiloxanes of the above formula IV or IVa having a carboxyl content of from 0.02 to 1.0 mmol/g and a molar mass in the range from 2.times.10.sup.3 to 60.times.10.sup.3 g/mol, fur skins.
In the hydrophobicizing of leather, use is generally made of silicone oils and functional siloxanes. In this context, carboxyl-containing polysiloxanes are preferably used. The term "carboxyl-containing" refers here and below both to undissociated COOH groups and to COO.sup.- groups afterdissociation. When these compounds are used, the leather can be treated in an aqueous liquor. Moreover, aftertreatment with metal salts, and the use of emulsifiers and solvents, are unnecessary. Such carboxyl-containing polysiloxanes are described in DE-A 35 29 869, DE-A 38 00 629 and WO-A 95/22627.
The service properties and performance results of such silicone oil emulsions, however, are still not optimal. Further improvements are desirable, in particular, in the stability of the emulsions during storage. Moreover, the strength of the hydrophobicizing effect and its durability when the known carboxyl-containing polysiloxanes are used is unsatisfactory. Furthermore, an improvement is desirable in the compatibility with paraffin oil emulsions as are used in the hydrophobicizing of leather. The carboxyl-containing polysiloxanes described in the abovementioned documents have the further disadvantage that they are of limited availability on the industrial scale and, in addition, are expensive.
Functional siloxanes which are more easily obtainable are aminoalkyl-functional siloxanes (also referred to below as aminosiloxanes). Moreover, they are in many cases economically more favorable than the carboxyl-containing polysiloxanes. When the aminosiloxanes are used for hydrophobicizing or impregnating leather, however, it has been found that their suitability for this application is limited. In particular, their hydrophobicizing effect is much poorer. Furthermore, the adhesion of the aminosiloxanes to chrome-tanned leather is very low, so that the durability of the hydrophobicizing effect also leaves much to be desired. Yet another disadvantage which has been found is that the use of aminosiloxanes causes unwanted yellowing.
DE-A 42 14 150 discloses a process for hydrophobicizing materials of fibrous structure using sulfosuccinic esters of reactive siloxanes.
EP-A 0 095 676 and polymer bulletin 32, pages 173-178 (1994) disclose the conversion of aminoalkylsiloxanes to carboxyamide-polysiloxanes. Such carboxyamide-polysiloxanes are also referred to as carboxy-functionalized aminoalkylsiloxanes. According to EP-A 0 095 676, such carboxyamide-polysiloxanes are used for textiles and woven fabrics. They impart to these materials a certain degree of softness and water

REFERENCES:
patent: 4931062 (1990-06-01), Bay et al.
patent: 5385999 (1995-01-01), D'Anvers et al.
patent: 5702490 (1997-12-01), Kneip et al.
Pinteala et al., Polymer Bulletin, 32, 1994, pp. 173-178.

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