Ciba Specialty Chemicals Corporation

Gill Jennings & Every Llp

Basf Se Corporation

Ann Hunt

Robert M O'Neil

Howard Roger Dungworth

Jonathan Campbell

John Whitworth

Alan Platt

John Mark Plonka

Karen O'Donoghue

William Walker

Robert Montgomery O'NEIL

The present invention provides a composition, which comprises an aqueous solvent and forms a transparent colorless coating, which yields markings of high contrast on exposure to energy. It also provides a process for the preparation of these compositions, substrates coated with these compositions and a process for their preparation, a process for preparing marked substrates using these compositions and marked substrates obtainable by the latter process.

Aqueous and transparent coatings for marking substrates

An improved process for the preparation of microcapsules consisting essentially of a wall material and a core material in condensing a melamine-formaldehyde precondensate and/or methyl ethers thereof in an aqueous dispersion of a water-insoluble core material and in the presence of an acrylic acid/acrylamide copolymer at acidic pH and at a temperature in the range of from 20&#xb0; to 100&#xb0; C., and hardening thereafter the melamine-formaldehyde precondensate to form the walls of the microcapsules at an elevated temperature, wherein the core material is dispersed in the precondensate/copolymer solution without initial partial condensation of the precondensate and copolymer and wherein the hydrophobe point of the precondensate and/or its methyl esters is less than 90&#xb0; C., as well as microcapsules, paper and pressure-sensitive recording material comprising such microcapsules.

Process for the preparation of microcapsules

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Stockport, United Kingdom

Ann Hunt