Bleaching and dyeing; fluid treatment and chemical modification – Treatment of hides – skins – feathers and animal tissues – Tanning
Patent
1996-08-15
1997-12-30
Diamond, Alan
Bleaching and dyeing; fluid treatment and chemical modification
Treatment of hides, skins, feathers and animal tissues
Tanning
8 9421, 8 9422, 8 9418, 8 9433, 252 857, 528 41, 528 26, 524837, C14C 900, C08L 8306
Patent
active
057024901
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/EP95/00418 filed Feb. 6, 1995.
The present invention relates to an improved process for the water repellent treatment of leather and skins with carboxyl-containing polysiloxanes in an aqueous emulsion in the presence of emulsifiers. The present invention furthermore relates to an agent for the water repellent treatment of leather and skins in the form of an aqueous emulsion.
EP-B-213 480 discloses a process for the water repellent treatment of leather and skins using an aqueous emulsion of from 15 to 90% by weight of silicone oil, from 5 to 30% by weight of an N-(C.sub.9 -C.sub.20 -acyl)amino acid as an emulsifier and from at least 5 to the remainder to make 100% by weight of water, which has a pH of from 5 to 12. For example, dimethyl polysiloxanes having on average from 2 to 10 carboxyl groups per molecule may be used as the silicone oil.
However, the performance characteristics and the results obtained during the use are not optimum in the case of such silicone oil emulsions. The stability of the emulsions, in particular during storage, and the compatibility with paraffin emulsions are unsatisfactory. The water repellent effect can also be further improved. Slight impairment of the finishing of the leathers during the water repellent treatment with these agents can also be observed in some cases. It is also intended further to reduce the amount of silicone oil used.
The water repellent effect of the existing systems is often insufficient for the requirements of the market, in particular of the US market. In the Maeser test usually employed there, flex values of >15000 are required. This cannot be achieved in a reproducible manner with the conventional products, so that in practice it is often necessary to carry out aftertreatment with solvent-containing silicones (application by spraying or by means of rollers). The solvent-containing products pollute the air. In addition, the silicone treatment of the surface complicates the finishing of the leathers, especially through adhesion problems. A further difficulty is that, when excessively large amounts of silicone are used, the resulting leather becomes too soft, for example as upper leather for shoes.
It is an object of the present invention to provide leather water repellents having correspondingly improved performance characteristics and giving improved results during use.
We have found that this object is achieved by a process for the water repellent treatment of leather and skins with carboxyl-containing polysiloxanes in an aqueous emulsion in the presence of emulsifiers, which comprises using polysiloxanes which are functionalized with carboxyl groups in a comb-like manner and in which the carboxyl groups are bonded to the polymer main chain via spacer groups in the form of linear or branched C.sub.2 -C.sub.40 -alkylene groups which may be interrupted by up to 8 non-neighboring oxygen atoms or groups of the formula --NR.sup.1 --, --CO-- or --CO--NR.sup.1 -- and in addition may carry up to 5 carboxyl groups or carboxamido groups of the formula --CO--NR.sup.1 R.sup.2, where R.sup.1 and R.sup.2 are each hydrogen or C.sub.1 -C.sub.4 -alkyl, the spacer groups being bonded to the polymer main chain via a direct bond or via an oxygen atom or a group of the formula --NR.sup.1 --, --CO--, --CO--NR.sup.1 -- or --CO--O--.
The essential function of the spacer group is to provide a certain distance between the silicone polymer main chain and the reactive carboxyl groups. The side chains composed of spacer groups and carboxyl groups are equivalent to the teeth of the comb molecule.
Linear polymethylene groups of the formula --(CH.sub.2).sub.m --, where m is from 2 to 40, in particular 5 to 25, especially from 8 to 18, and C.sub.2 -C.sub.40 -alkylene, in particular C.sub.5 -C.sub.20 -alkylene, especially C.sub.8 -C.sub.18 -alkylene, groups which are branched, in particular only slightly branched, ie. have on average not more than one methyl or ethyl group per 3 carbon atoms in the linear part of the chain, are preferred for such
REFERENCES:
patent: 4701269 (1987-10-01), Bay et al.
Danisch Peter
Kneip Michael
BASF - Aktiengesellschaft
Diamond Alan
LandOfFree
Water repellent treatment of leather and skins with polysiloxane does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Water repellent treatment of leather and skins with polysiloxane, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Water repellent treatment of leather and skins with polysiloxane will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-198279