Abstract: There are disclosed three kinds of pressure sensitive recording papers obtained by combining a colored oil-soluble dye, a microcapsule containing organic liquid and a whitening agent. These pressure sensitive recording papers have advantages that a record image of sufficient color density can be obtained by using said dye in only a small quantity, they are resistant to light, heat, chemicals, etc., they are excellent in conservability, and so on.

Abstract: A transfer-onto-plain paper type pressure-sensitive copying paper which is excellent in transferability and coloring property could be obtained by coating in monolayer to one surface of a substrate a colorless electron-donating color former, a colorless electron-accepting color developer which reacts with said color former to give a colored product, and a wax mixture comprising an amide wax selected from the group consisting of saturated fatty acid amides having 14 or less carbon atoms and unsaturated fatty acid amides having one or more unsaturated bonds, and other wax.

Abstract: A transfer-onto-plain paper type pressure-sensitive copying paper having a colorless coating layer which forms a transferred colored image could be obtained by coating a substrate with double capsules and wax enclosing said double capsules, which double capsules have been prepared by previously forming primary microcapsules containing, as a core material, either colorless electron-donating color former or colorless electron-accepting color developer which reacts with said color former to give a colored product, enclosing the formed primary microcapsules in whichever of the color former or the color developer is not contained in the primary microcapsules, and then microencapsulating the enclosed primary microcapsules to form double capsules.

Abstract: A process is disclosed for producing microcapsules, which comprises gelating oil-containing capsules having capsule walls of coacervates, and using at least two kinds of chemical hardening agents in a hardening step;--the hardening agent to be added at first serving to act slowly upon the capsule walls and the hardening agent to be added later serving to act rapidly.