Abstract: A heat-sensitive recording material comprising a support having provided thereon a heat-sensitive color-forming layer which contains a colorless or slightly colored electron-donating dye precursor and an electron-accepting compound capable of reacting with the electron-donating dye precursor to form color, wherein the heat-sensitive color-forming layer further contains at least one of the compounds represented by the general formulae (I) to (VI) shown in the specification and at least one of the compounds represented by the general formulae (VIII) to (XII) shown in the specification, or wherein the heat-sensitive color-forming layer further contains about 0.5 wt % to less than about 20 wt %, based on the electron-accepting compound, of the compound represented by the general formula (XIII) shown in the specification. The heat-sensitive recording material obtained provides a high density color image and does not undergo a decrease in heat responsibility and an increase in background fog formation.

Abstract: A recording material containing an electron donating leuco dye and an electron accepting compound, wherein said electron accepting compound is a salicyclic acid derivative having an alkyl group, an alkoxy group or an aryloxy group as a substituent or a metal salt thereof. The recording material has satisfactory color developability, working preservability and stability.

Abstract: A novel heat-sensitive recording material comprising a support having coated thereon a heat-sensitive coloring layer containing a colorless or light-colored electron donor dye precursor and an electron acceptor compound which colors upon reaction with said electron donor dye precursor and a protective alyer coated on the heat-sensitive coloring layer comprising a saponified product of a vinyl acetate-acrylamide copolymer or vinyl acetate-methacrylamide copolymer having an acrylamide or methacrylamide content of about 0.5 to about 80% by weight.

Abstract: A heat-sensitive recording sheet comprises a colorless or pale-colored electron donating colorless dye precursor, an electron accepting compound which forms color when reacted upon heating with the colorless dye precursor and a heat-fusible substance. The electron accepting compound is 1,4-bis(p-hydroxycumyl) benzene and the heat-fusible substance is 1-p-ethylphenoxy-2-phenoxyethane.

Abstract: A heat-sensitive recording material is described, comprising a heat-sensitive color forming layer containing a colorless or pale colored electron donating dye precursor and an electron accepting compound that reacts with said dye precursor to develop color, wherein said electron accepting compound is a bishydroxycumylbenzene or bishydroxy-.alpha.-methylbenzylbenzene compound.

Abstract: A heat-sensitive recording paper is described, comprising a support having formed thereon a heat-sensitive recording layer containing a colorless or pale-colored electron donating dye precursor and an electron accepting substance that reacts with said electron donating dye precursor to develop color, and an overlying protective layer containing a water-soluble polymeric binder and a pigment, wherein the back side of the support is provided with a backcoat layer containing an alkali salt of a styrene-maleic acid copolymer.

Abstract: A recording material is disclosed which contains an electron donating colorless dye and an electron accepting compound. The electron accepting compound is an aromatic compound having a substituted or unsubstituted sulfamoyl group and a hydroxyl group as substituents. The recording material can provide high density images which provide sufficient fastness during storage.

Abstract: A heat-sensitive recording paper is disclosed, comprising a base having thereon (a) a heat-sensitive color forming layer containing a substantially colorless electron donating dye and an acid substance capable of forming a coloration by coming into contact with said dye upon heating, wherein a coating layer containing a binder comprising modified polyvinyl alcohol containing silicon atoms in the molecule and at least one of colloidal silica and amorphous silica is provided on said color forming layer.

Abstract: A process for producing a heat-sensitive recording paper is disclosed. The process involves pretreating base paper by a high-frequency corona discharge. The base paper treated in this manner can be utilized in producing a heat-sensitive recording material by providing a heat-sensitive layer thereon. By subjecting the base paper to the high-frequency corona discharge treatment the base paper can be uniformly coated with a heat-sensitive recording material without leaving any blank spaces thereon.

Abstract: A heat-sensitive recording sheet comprised of a support base having a heat-sensitive color forming layer thereon is disclosed. The layer is comprised of an electron donating dye, an electron accepting compound which reacts with the dye to form a color and a surface active agent. The surface active agent has a structure of ##STR1## as a hydrophobic atomic group, wherein R.sub.1 and R.sub.2 independently represent an alkyl group having 3 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, an aralkyl group having 7 to 18 carbon atoms, or a cycloalkyl group having 5 to 10 carbon atoms. The heat-sensitive recording sheet has high sensitivity, produces high density color images and results a reduced amount of background fog.

Abstract: A heat-sensitive recording material is disclosed. The material is comprised of an electron donating dye, electron accepting compound and a sensitivity improving agent thereon. The sensitivity improving agent is a compound represented by the general formula (I) ##STR1## wherein R.sub.1 and R.sub.2 independently represent an alkyl group, an aralkyl group, an aryl group, an alkoxy group having 12 or less carbon atoms or a halogen atom, and m and n independently represent 0 or an integer of 5 or less. By including the sensitivity improving agent, it is possible to obtain a heat-sensitive recording material which produces an image of high color density.

Abstract: A heat-sensitive recording paper which is comprised of a support base having a heat-sensitive color forming layer thereon is disclosed. The layer contains a colorless or faint color electron donating dye, a bisphenol and a straight chain fatty acid amide. The recording sensitivity of the paper is greatly increased by incorporating a phenol derivative having the general formula ##STR1## wherein R is an alkyl group or an aralkyl group and Y represents a phenyl group, an alkyl group, a cycloalkyl group or a halogen atom.