Ciba Specialty Chemicals Corporation

Ciba-geigy Corporation

Daniel Thibaut

Benjamin Breitenstein

Andr&eacute; Geoffroy

Christoph Kleiner

Andr&eacute; Schmitter

Matthias Von Frieling

Martin Von B&uuml;ren

Sebastian Staubli

Hans Horisberger

Ariane Higel

Linda Kirchberger

The present invention relates to aqueous dispersions for solid phenolic antioxidants, wherein the antioxidants are dispersed in the aqueous phase with polyvinyl alcohol as dispersing agent. The invention also relates to a process, which comprises stabilising a polymer material against oxidative, thermal or light-induced degradation by adding to the polymer the aqueous dispersion.

Aqueous dispersions for antioxidants

A description is given of an extrusion process for the preparation of a low-dust stabiliser, using a subcooled melt as granulation liquid, as well as of novel amorphous modifications of different stabilisers, including 2,2&prime;-methylenebis(4-&lsqb;1,1,3,3-tetramethylbutyl&rsqb;-6-benzotriazol-2-yl-phenol), and of the &bgr;-crystalline modification of 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole and of the preparation thereof. The novel process affords products which are easy to handle and which are flowable, and the novel modifications have advantages as regards their preparation, processing and their use as stabiliser.

Preparation of low-dust stabilisers

A description is given of an extrusion process for the preparation of a low-dust stabilizer, using a subcooled melt as granulation liquid, as well as of novel amorphous modifications of different stabilizers, including 2,2&prime;-methylenebis(4-&lsqb;1,1,3,3-tetramethylbutyl&rsqb;-6-benzotriazol-2-yl-phenol), and of the &bgr;-crystalline modification of 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole and of the preparation thereof. The novel process affords products which are easy to handle and which are flowable, and the novel modifications have advantages as regards their preparation, processing and their use as stabilizer.

Preparation of low-dust stabilizers

Low-dust granules of plastic additives, comprising at least 10% by weight of calcium stearate, where the water content of the calcium stearate is less than 2%, having a particle size distribution, in accordance with ISO 3435, of from 1 mm to 10 mm, a loose bulk density of greater than 400 g/l and a flowability in accordance with DIN 53492 of less than 15 s (tR25), a process for their production, and the use of these granules for the stabilization of organic polymers.

Low-dust granules of plastic additives

There is disclosed a process in which a melt of a 2-aryl-2H-benzotriazole containing colored contaminants, or a solution thereof in an organic nonpolar solvent, is purified by treatment with a strongly acidic synthetic cationic exchange resin.

Growing community of inventors

Blotzheim, France

Daniel Thibaut