Patent · US Expired

Preparation of expandable thermoplastic polymers by post-impregnation

US5561170A · kind A · utility

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7Claims

0Family size

Assignee

BASF SE

Inventors

Michael Witt · Ludwigshafen, DE
Klaus Hahn · Lampertheim, DE
Maria Lorenz · Ludwigshafen, DE

Key dates

Filing date	Apr 20, 1995
Grant date	Oct 1, 1996
Priority date	—
Expiry date	Apr 20, 2015

Classification

Technology area (CPC C)Chemistry; Metallurgy
CPC primaryC08J9/18
WIPO fieldOther special machines
WIPO sectorMechanical engineering

Abstract

A process for the preparation of expandable thermoplastic polymers by post-impregnation with a blowing agent in aqueous suspension in the presence of a mixture of magnesium pyrophosphate and a sulfonate group-containing extender as suspension stabilizer, in a reactor comprises PA1 a) preparing the magnesium pyrophosphate in the same reactor at below 50.degree. C. by adding a solid magnesium salt in an amount corresponding to an at least 3% stoichiometric excess, based on pyrophosphate, to an aqueous solution of the pyrophosphate, PA1 b) heating the suspension medium to from 70.degree. to 140.degree. C. and PA1 c) adding the blowing agent in this temperature range.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.