Abstract: In a process for producing oil-containing microcapsules by coacervation comprisingA. introducing a fine powder or hydrophobic liquid into a high molecular weight electrolytic wall-forming colloid;B. coacervating the resulting dispersion or emulsion;C. cooling the resulting coacervate to gel it and form the wall of said microcapsules; andD. hardening said wall of said microcapsules; the improvement which comprises adding a phenolic compound to the system.

Abstract: In a process for hardening microcapsules produced by microencapsulating hydrophobic oil droplets using a complex coacervation process with gelatin as one of the hydrophilic colloids: including the steps of1. emulsifying a water-immiscible oil in an aqueous solution of at least one first hydrophilic colloid ionizable in water and admixing an aqueous solution of at least one second hydrophilic colloid having an electric charge opposite to that of said first colloid,2. causing coacervation of said colloids to occur by adding water thereto or adjusting the pH thereof to form coacervates,3. cooling said coacervates to cause gelling thereof,4. adjusting the pH to alkalinity and adding a hardening agent sequentially or simultaneously,5. increasing the temperature so as to cause hardening, the improvement wherein glyoxal or glutaraldehyde in combination with formaldehyde is present during step (4).

Abstract: A pressure-sensitive recording sheet which comprises a support having thereon a color former-containing microcapsule coating, the microcapsule coating comprising at least two microcapsule layers with the mean particle size of the microcapsules in the microcapsule layer closest to the support being larger than the mean particle size of the microcapsules in the microcapsule layer farther away from the support.

Abstract: A pressure-sensitive recording sheet which comprises a support having thereon a color former-containing microcapsule coating, the microcapsule coating comprising at least two microcapsule layers with the color former concentration in the microcapsules in the microcapsule layer closest to the support being higher than the color former concentration in the microcapsules in the microcapsule layer farther away from the support.

Abstract: In a process for producing microcapsules containing hydrophobic oil drops by complex coacervation including a conventional prehardening treatment in which an aldehyde and an alkali material are added to the system, the improvement which comprises adding gelatin having an isoelectric point lower than that of the gelatin employed for forming the walls of the coacervates to the system at a temperature lower than the gelling point of the gelatin employed for forming the walls of the coacervates, but prior to the simultaneous presence in the system of said aldehyde and alkali material, in an amount sufficient to prevent an increase in viscosity due to the reaction of gelatin and aldehyde during said prehardening step.

Abstract: A pressure-sensitive copying paper comprising an adsorbent solid acid and a microencapsulated color former capable of forming a distinct color when reacted with the adsorbent acid coated on the same or a different surface of a support or supports, the microencapsulated color former being at least one lactone compound of a pyridine-carboxylic acid represented by the formula ##SPC1##Or a mixture thereof, wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and A are as defined hereinafter, is disclosed.

Abstract: A pressure-sensitive copying paper comprising an adsorbent solid acid and a microencapsulated color former capable of forming a distinct color when reacted with the adsorbent acid coated on the same or a different surface of a support or supports, the microencapsulated color former being at least one lactone compound derived from a pyridine-carboxylic acid represented by the formula ##SPC1##Or a mixture thereof, wherein R.sub.1, R.sub.2, R.sub.3 and the partial structure ##SPC2##Are as defined hereinafter, is disclosed.

Abstract: A 1,3-dihydro-1-oxo-benzo[b]thieno[2,3-C]furan derivative represented by the following General Formula I ##SPC1##or a 1,3-dihydro-3-oxo-benzo[b]thieno[2,3-C]furan derivative represented by the following General Formula II: ##SPC2##wherein ring A represents a benzene ring or a naphthalene ring, R.sub.1 and R.sub.2 each represents an amino group, and X, Y and Z each represents a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkoxy group, an aralkoxy group, an acyloxy group, a nitro group or an amino group, useful as a color former, e.g., in a pressure sensitive copying paper.