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:
Oct. 23, 1990
Filed:
Mar. 18, 1988
Gunter Pietsch, Isernhagen, DE;
Karl-Heinz Schrader, Hanover, DE;
Abstract
A description is given of a process for microencapsulating hydrophobic oils with color reactants of color reaction sytems dissolved therein, a cationized melamine/formaldehyde precondensate being precipitated in ultra-fine suspension from its acid aqueous solution, accompanied by vigorous stirring and by modifying the solubility conditions, said suspension is mixed under vigorous stirring with a hydrophobic oil containing the color reactants in dissolved form, the oil-in-water dispersion obtained is adjusted acid and an aqueous solution of a water-soluble, nonionic melamine/formaldehyde precondensate is added, accompanied by stirring, for forming the microcapsule envelope. For stabilizing the oil-in-water dispersion, the pH-value of the acid, aqueous solution of a cationized melamine/formaldehyde precondensate which, in the weak acid, neutral and alkaline, aqueous use range is present in insoluble, cationizable form, is raised in the absence of water-soluble, organic polymers by the addition of Bronsted bases and accompanied by vigorous stirring to such an extent that the cationizable melamine/formaldehyde precondensate is precipitated in ultra-fine suspension as a result of the modified solubility conditions. The possible elimination of the water-soluble, organic polymers is economically advantageous.