Low-formaldehyde dispersion of microcapsules of melamine-formaldehyde resins

US6224795A · kind A · utility

Assignee

• BASF SE

Inventors

• Gabriele Frank · Mannheim, DE
• Ralf Biastoch · Speyer, DE

Key dates

• Filing date: Jul 26, 1999
• Grant date: May 1, 2001
• Expiry date: Jul 26, 2019

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/2985
• WIPO field: Chemical engineering
• WIPO sector: Chemistry

Abstract

A process for the preparation of microcapsules by the condensation of melamine-formaldehyde resins and/or the methyl ethers thereof in water, in which the substantially water-insoluble material forming the core of the capsule is dispersed, in the presence of an anionic protective colloid at pH's of from 3 to 6.5 by the formation of the microcapsules at temperatures of from 20.degree. to 50.degree. C. followed by curing of the shell of the capsules at from >50.degree. to 100.degree. C., in which, prior to curing, from 10 to 200 wt % of urea, whose amino groups are optionally linked to an ethylene or propylene bridge, based on the melamine-formaldehyde resin are added, the microcapsules produced by this process and also the use thereof in a pressure-sensitive recording system.