Toppan Moore Co., Ltd.

Kei Etoh

Akira Hirasawa

Makoto Kawamura

Hisano Higurashi

Masafumi Moriwaki

Hiroyuki Sekihara

A microcapsule-containing oil-based coating liquid wherein the coating liquid comprises a hydrophobic core material-containing microcapsule particles dispersed individually in a state of primary particle in an oil varnish for ink use or a resin for coating use, and a solvent having an affinity for both the varnish or the resin and the surface of the microcapsule wall material in a state of having been attracted with the affinity to both the varnish or the resin and the surface layer of the microcapsule wall material. The preferred solvent is a lower divalent or multivalent alcohol. A preparative method of the foregoing coating liquid by utilizing vacuum distillation is also proposed. A sheet, like a duplicating sheet of paper coated with the foregoing oil-based coating liquid is further provided. According to the present invention, a water-based microcapsules system can be advantageously converted into an oil-based one without coagulating the primary microcapsule particles. There is no hardening and breakdown of the wall material during the process, and the original strength and the flexibility of the microcapsule wall material can be retained intact. Conventional pressure transferring-type printing machine may be employed to printing a selected area of the sheet.

Microcapsule-containing oil-based coating liquid, ink, coated sheet, and

Microcapsules are prepared by adding a methylolated melamine or methylolated urea to an aqueous emulsion of the core material dispersed in an aqueous solution of a styrene/maleic anhydride copolymer partially hydrolyzed in an alkaline condition and heating the mixture at 40.degree. to 90.degree. C. in an acidic condition so that a reaction product forming the capsule walls is produced by the esterification reaction between the carboxyl groups in the partial hydrolysis product and the methylol groups in the methylolated melamine or urea and the amidation reaction between the carboxylic anhydride groups in the former and the amino groups in the latter. By virtue of the three dimensional network structure, the capsule walls are very dense and highly resistant against heat, water and solvents.

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Tokyo, Japan

Kei Etoh