Leather-treatment agents, process for their preparation, and the

Details Leather-treatment agents, process for their preparation, and the Leather-treatment agents, process for their preparation, and the

1999-03-09

2000-04-11

Green, Anthony

Compositions

Leather or fur treating

C14C 900, C14C 902

Patent

active

060484675

DESCRIPTION:

BRIEF SUMMARY
The invention relates to new leather dressing agents for the manufacture of leathers having low contents of volatiles, particularly for car upholstery high-quality leathers, a process for producing said agents, and their use in manufacturing low-fogging leathers. Car upholstery leathers must meet specific criteria. On the one hand, softness is essential, as is light-fastness and resistance to heat influence on the other hand, and finally, the so-called fogging behavior. In DIN 75201, fogging is defined as condensation of volatiles evaporated from the vehicle interior equipment on the glass panes, particularly the windshield. That same standard also describes a gravimetric and a reflectometric procedure for characterizing the fogging behavior of leather.
EP 498,634 A2 recommends specific polymers for the manufacture of low-fogging leather, where the dispersions are substantially free of organic solvents and contain an amphiphilic copolymer consisting of a predominant part of at least one hydrophobic monomer and a minor part of at least one hydrophilic monomer. In a gravimetric test according to DIN 75201, the treatment of leather using these dispersions provides good results. There is no disclosure of reflectometric examinations.
The amphiphilic copolymers are preferably produced in an aqueous emulsion polymerization. However, due to the different hydrophilicity of the copolymers employed, this inherently gives rise to problems with the copolymerization behavior which, in the extreme case, may result in the situation that each of the monomers undesirably forms separate homopolymers. Another consequence of the per se unfavorable solution conditions is an expensive subsequent processing in order to destroy residual monomers. To achieve good emulsion stability, it is also necessary to add a sufficient amount of an emulsifier (lauryl sulfate was used in the examples mentioned), which may give rise to waste water problems in leather processing.
Furthermore, it is well-known to produce fat chemical raw materials by polymer-analogous reaction with fatty alcohols. Fundamental principles are described in Fat Sci. Technol. 92, No. 10, pp. 397-400. Even though possible fields of use have been discussed, applications in the manufacture of leather have not been described.
DE 42 05 839 A1 describes the reaction of polymers of a) 30-100 mole-% of unsaturated dicarboxylic anhydrides, b) from 0 to 70 mole-% of one or more vinylaromatics, c) 0-70 mole-% of vinyl esters of C.sub.1 -C.sub.8 carboxylic acids, d) 0-50 mole-% of C.sub.2 -C.sub.6 olefins, e) 0-30 mole-% of unsaturated C.sub.3 -C.sub.5 carboxylic acids, and up to 10% of other copolymerizable monomers, with hydrophobic amines or alcohols. The resulting products impart particular softness to leathers treated therewith.
One drawback of this procedure is the high amount of poorly polymerizable dicarboxylic anhydrides, which is why severe conditions of polymerization must be chosen to obtain a low ratio of low molecular weight substances in the final product, which is required for good fogging behavior. This fact is confirmed by the data in the examples: polymerization temperature at the boiling point of the xylene solvent, about 136-140.degree. C., at least 3 hours.
EP 466,392 B1 describes a process for the production of polymers which contain both lateral hydrophobic groups and lateral alkoxylated groups and are obtained according to common methods by a derivatization of polymers subsequent to the actual polymerization process. Thus, it is preferred to produce polymers from simple monomers such as acrylamide and/or acrylic acid using conventional polymerization, followed by derivatization using a mixture of primary or secondary hydrophobic amines and primary or secondary alkoxylated amines. Such polymer derivatives are used as thickening agents and dirt-solving agents.
It was therefore the object of the invention to provide new leather dressing agents which are easy to produce, substantially auto-emulsifying and low in residual monomers, a process for their production

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