Ciba Specialty Chemicals Corporation

Ciba-geigy Corporation

Basf Se Corporation

Benjamin Breitenstein

Daniel Thibaut

Martin Von Büren

Christoph Kleiner

Andr&eacute; Schmitter

Andr&eacute; Geoffroy

Matthias Von Frieling

Martin Von B&uuml;ren

Thomas Georg Gfrörer

Rolf Waldner

Pierre Lutz

Linda Kirchberger

André Geoffroy

André Schmitter

The invention relates to a technically advantageous method of producing low-dust granules of polymer additives or polymer additive mixtures. The granule-forming polymer additives are mixed together, the mixture is converted into a workable mass and pressed through an orifice. The pre-shaped strand-like extruded mass is cooled and, while still in a workable state, formed into granules by rolling, impressing, cooling and comminuting.

Method of producing low-dust granules from polymer additives

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

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Rheinfelden, Switzerland

Benjamin Breitenstein