To provide a heat-sensitive recording material which produces images with excellent resistance to water, while producing background with resistance to heat. A heat-sensitive recording material which is characterized by containing at least one compound represented by general formula (1) as a color-developing compound:

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wherein, R1-R5 each independently represents a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group or an arylamino group.

The content of compound(s) having a molecular weight of 650-670, typically a molecular weight of 660, as measured by mass spectrometry, is reduced to 0.5 mass % or less in a heat-sensitive recording material comprising 3,3-diallyl-4,4-dihydroxy diphenylsulfone, or in a diphenylsulfone or a color-developing agent. Provided is, thereby, a heat-sensitive recording material, a color-developing agent, or a diphenylsulfone which cause less background fogging under moisture and heat conditions and which has excellent preservation stability of a colored image.

A thermosensitive recording material including a support and a thermosensitive coloring layer provided on the support, in which the thermosensitive coloring layer contains (A) a coloring substance, (B) a kraft lignin in which a content of dimethyl disulfide is 2.5 ppm or less and (C) a specific developer.

The objective of the present invention is to provide a thermosensitive recording medium excellent in color developing property, especially excellent in bar code readability, under severe environment. Provided is a thermosensitive recording medium having a thermosensitive recording layer comprising a colorless or pale colored electron donating leuco dye and an electron accepting color developing agent on a substrate, wherein the thermosensitive recording layer contains a specific sulfone compound and a specific urea-urethane-based compound in a specific ratio.

A thermosensitive recording body has at least a thermosensitive recording layer and a topcoat layer formed on a substrate. The substrate consists of a transparent film. At least the thermosensitive recording layer and the topcoat layer includes a diffuse reflection suppressor component that suppresses diffuse reflection of light from particles constituting the thermosensitive recording layer and the topcoat layer.

A laser markable composition includes (a) an aqueous medium; (b) capsules composed of a polymeric shell surrounding a core; (c) a colour developing agent or colour developing agent precursor; and (d) an optothermal converting agent; characterized in that the core of the capsule contains a leuco dye.

Aqueous composition comprising a color former, a developer, and a binder, wherein (a) the weight ratio between the developer and the color former is in the range of from 1 to 5; (b) the binder comprises an acrylate binder, comprising acrylic acid and styrene, and at least one additional monomer selected from the group consisting of -methyl styrene, ethyl acrylate and 2-ethylhexyl acrylate; and (c) the color former and/or the developer are present in an un-encapsulated form; a process for the preparation of these compositions, substrates coated with this composition and a process for its preparation, and a process for preparing a marked substrate using this composition.

A main object of the present invention is to provide a thermosensitive recording material having excellent recording color developability and recording image quality, having no inhibition of a color-developing reaction due to the adhesive component after being processed into a thermosensitive recording label (glue desensitization), and being able to withstand long-term storage while retaining excellent recording performance. The present invention is a thermosensitive recording material (1) having at least an anchor layer (1) containing a sizing agent on a support, an undercoat layer containing at least one member selected from the group consisting of plastic hollow particles and sizing agents on the anchor layer (1), and a thermosensitive recording layer containing a leuco dye and a coloring agent on the undercoat layer; and is a thermosensitive recording material (2a) having an anchor layer (2) containing specific amounts of a pigment and a specific sizing agent on a support, and a thermosensitive recording layer containing a leuco dye and a coloring agent on the anchor layer (2); a thermosensitive recording material (2b) having an anchor layer (2) containing a pigment and a specific sizing agent on a support, and a thermosensitive recording layer containing a leuco dye and a specific coloring agent on the anchor layer (2); or a thermosensitive recording material (2c) having an anchor layer (2) containing a sizing agent and a water resistance-imparting agent on a support, and a thermosensitive recording layer containing a leuco dye and a coloring agent on the anchor layer.

An object of the invention is to provide a recording material and recording sheet having excellent color-developing performance, storage stability, etc. A recording material having good color-developing performance and storage stability may be obtained by using a specific compound having a benzhydrol skeleton as an additive in a recording material employing color development through a reaction between a color former and a color-developing agent.

Disclosed is a heat-sensitive recording material containing at least an undercoat layer and a heat-sensitive recording layer in this order on a support, the undercoat layer containing hollow particles, a binder, and an inorganic pigment I, the heat-sensitive recording layer containing a leuco dye and a developer, wherein (A) the heat-sensitive recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N,N-bis-(3-methylphenyl)-isophthalic acid diamide as a stability improver, or (B) the heat-sensitive recording layer contains 5-(N-3-methylphenyl-sulfonamide)-N,N-bis-(3-methylphenyl)-isophthalic acid diamide as the developer and contains a pigment with an oil absorption of 130 ml/100 g or less as an inorganic pigment II.