The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 27, 1983
Filed:
Sep. 30, 1980
Wolfgang Sliwka, Weinheim, DE;
BASF Aktiengesellschaft, Rheinland-Pfalz, DE;
Abstract
In a process for the preparation of microcapsules based on a melamine-formaldehyde resin, in which the microcapsules are obtained by condensing a melamine-formaldehyde precondensate, its C.sub.1 -C.sub.4 -alkyl ethers, or mixtures thereof, in water in which the material forming the capsule core is dispersed, at a pH of from 3 to 6.5 and at from 20.degree. to 100.degree. C., the improvement that the water contains a homopolymer or copolymer which possesses sulfonic acid groups but is devoid of phenyl or sulfophenyl groups and has a K value of from 100 to 170 or a viscosity of from 200 to 5,000 mPa.s (shearing gradient 489 s.sup.-1 ; 20% strength solution at 25.degree. C.), and that the melamine-formaldehyde precondensate is added continuously, or in portions, in step with the rate of condensation. The process gives individual capsules which are highly impermeable. The capsules are exceptionally useful for the production of pressure-sensitive recording materials.