Abstract: An improved pressure sensitive recording sheet capable of causing an improved color development which comprises a substrate and a layer containing microcapsules each containing an electron-donative chromogenic material and a hydrophobic medium containing benzyl toluene being formed on the substrate.The pressure sensitive recording sheet exhibits an excellent color-developing property and provides clear color images of high density.

Abstract: A microcapsule-containing ink composition for flexographic printing containing microcapsules, an adhesive and an ink medium, the composition being characterized in that the adhesive includes a polymer composed of a methacrylate or acrylate singly or as its main component and having an average molecular weight of 3000 to 50,000.

Abstract: A non-aqueous printing ink composition containing a microcapsule and a microencapsulated ink composition characterized in that the microcapsule has a capsule wall comprising melamine-formaldehyde resin and has an average particle size of 1.8 to 3.5.mu..

Abstract: In a microencapsulation process which comprises polycondensating a hydrophilic melamine-formaldehyde resin type precondensate in water or in a hydrophilic medium containing an emulsifier to form capsule wall film around a hydrophobic core material to obtain microcapsules, the process which is characterized in that the emulsifier is a copolymer of (1) an unsaturated monobasic acid monomer of at least 80 mole %, (2) a hydrophobic monomer and (3) a hydrophilic monomer other than a carboxylic acid.

Abstract: A pressure sensitive manifold sheet characterized in that a chelate record material comprising an iron (III) compound and/or a vanadium compound, and an aromatic compound having at least one of hydroxyl group and mercapto group on the aromatic ring in combination therewith is used further in combination with an infrared absorbing organic compound.

Abstract: A process for producing a powder of microcapsules characterized by adding an aldehyde resin precondensate to a microcapsule dispersion prepared in water or a hydrophilic medium with use of a water-soluble high molecular compound as an emulsifier, maintaining the resulting mixture in a condition for promoting polycondensation of the precondensate, and removing the dispersing medium from the reaction mixture, and a process for producing a powder of microcapsules characterized by emulsifying a hydrophobic core material containing a specific oil-soluble melamine-formaldehyde resin precondensate in water or a hydrophilic medium, subjecting the emulsion to a condition for promoting polycondensation to form capsule wall films and obtain a microcapsule dispersion, and thereafter removing the dispersing medium from the dispersion are disclosed.Further, processes for producing a non-aqueous microcapsule composition are also disclosed.

Abstract: In a microencapsulation process which causes hydrophobic core material containing an oil-soluble melamine-formaldehyde precondensate to emulsified in water or in a hydrophilic medium, and to form capsule wall film under conditions for promoting polycondensation, the process which is characterized in that said oil-soluble melamine-formaldehyde precondensate is 40 to 100% in a degree of formaldehyde substitution, 80 to 100% in alkylation degree, and 4 to 11 in hydrophobic degree.

Abstract: This invention concerns with an improved microcapsule dispersion prepared by adding the following components to a known microcapsule dispersion containing PVA; a pulp having a specific weighted average fiber length, another type of pulp, carboxymethyl cellulose and/or a specified periodic acid type compound, and is characterized by overcoming the drawbacks of known microcapsule dispersions attended by use of PVA.

Abstract: The method of making oil-containing microcapsules comprises the steps of (1) preparing an aqueous system comprising an aqueous solution of at least two kinds of hydrophilic colloid materials with opposite electric charges and oil droplets dispersed in said solution (2) causing coacervation in said aqueous system at a temperature above the gelation points of said hydrophilic colloid materials to form a coacervate suspension in which each of said oil droplets is surrounded by a coacervate and (3) cooling said coacervate suspension to a temperature below the gelation points of said hydrophilic colloid materials to form multi-nucleus capsules. During the step of cooling the coacervate suspension, aggregation of particles of oil droplets each having a coacervate therearound is controlled by an agitation flow so as to allow formation of multi-nucleus microcapsules having an average diameter within the range of 3 to 20 microns.

Abstract: In a process for producing microcapsules of complex hydrophilic colloid material enclosing fine particles of a hydrophobic substance, the improvement characterized in that:An acid-treated gelatin and at least one of carboxy-modified cellulose derivatives are used as the hydrophilic colloid materials, the amount of the cellulose derivative being 1/7 to 1/40 the amount of the gelatin by weight, the cellulose derivative having an average polymerization degree of 50 to 1,000 and a carboxyl substitution degree of 0.4 to 1.5, andThe coacervation of the colloid material solution is effected at a pH of 4.8 to 6.0.