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, and a protective layer on the thermosensitive recording layer, wherein the thermosensitive recording layer contains at least one kind of urea compound represented by the following general formula (Formula 1) as the electron accepting color developing agent, and wherein the protective layer contains an acrylic resin

##STR00001##

(wherein X represents O or NH, R.sup.1 represents a hydrogen atom or SO.sub.2R.sup.3, R.sup.3 represents a substituted or unsubstituted alkyl group, an aralkyl group or an aryl group, R.sup.2 represents a hydrogen atom or an alkyl group, m represents an integer of 0 to 2, and n represents 0 or 1).

The purpose of the present invention is to provide a heat-sensitive recording material having improved thermal responsiveness and improved storage stability of a printed area and background, compared to conventional heat-sensitive recording materials containing a non-phenolic compound as a color developer. The present invention pertains to a heat-sensitive recording composition containing a color former, a color developer, a sensitizer, and a stabilizer, wherein the color developer is [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate, N-[2-(3-phenylureido)phenyl]benzenesulfonamide, or N-(p-toluenesulfonyl)-N-(3-p-toluenesulfonyloxyphenyl)urea, the sensitizer is diphenylsulfone or 1,2-bis(3-methylphenoxy)ethane, and the stabilizer is 1,3-diphenylurea.

We disclose specialized direct thermal recording media that are both phenol-free and water-dispersible. The thermally responsive layer of such media includes a leuco dye and an acidic developer. To avoid image fade and image formation problems associated with certain demanding environmental storage conditions, the developer is not only phenol-free but also a derivative of N,N-diphenylurea. The thermal recording medium also includes a base coat between the substrate and the thermally responsive layer, the base coat containing a non-water-soluble binder, and a top coat carried by the substrate such that the thermally responsive layer is between the top coat and the substrate.

An aqueous inkjet ink for forming a colour upon heat treatment includes a) an immobilized leuco dye; b) a colour developing agent or colour developing agent precursor; and c) optionally an opthothermal converting agent; wherein the leuco dye is immobilized by being covalently bonded to polymeric particles or by being included in the core of capsules composed of a polymeric shell surrounding a core.

A heat-sensitive recording material includes a heat-sensitive recording layer containing a basic dye and a developer and provided on a supporting body, in which the developer is at least one type of an N-substituted amino acid derivative represented by the following General Formula:

(RX).sub.mY(Z).sub.m(1)

(In Formula (1), R represents an alkyl group or an aryl group which may have a substituent. X is a group bonded to the N-terminus of Y, and represents OCO, SO.sub.2NHCO, NHCO, NHCS, or SO.sub.2. Y represents an amino acid residue or a peptide residue. Z represents a group bonded to the C-terminus of Y and represents an OH group or an OR group. When Y is an amino acid residue other than a cystine residue or when Y is a peptide residue not having a cystine residue, m=1, and when Y is a peptide residue having n cystine residues, m=n+1 and n is 1 or 2.)

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 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.

A laser markable composition includes (a) an aqueous medium; (b) polymeric particles dispersed in the aqueous medium; (c) a colour developing agent or colour developing agent precursor; and (d) an optothermal converting agent; characterized in that a leuco dye is covalently bonded to the polymeric particles.

Heat sensitive recording material, recording sheets formed from heat sensitive recording material, and methods for forming images using heat sensitive recording material are provided. An exemplary heat sensitive recording material includes a color forming compound, a first non-phenolic color developer, and a second non-phenolic color developer.

Non-phenolic direct thermal recording media have a thermally responsive layer containing a leuco dye and a plurality of non-phenolic developers including 1,3-diphenyl urea (DPU) and urea urethane (UU). This chemistry enables multi-purpose recording materials capable of withstanding multiple different types of environmental conditions or agentssuch as a water soak, contact with polyvinyl chloride meat wrapping film, boiling water, dry and humid heat, sunlight, and contact with hand sanitizer. The unique non-phenolic chemistry allows the product's thermally responsive layer to have an ultra-low coat weight, less than 1.48 g/m.sup.2.