Use of N-(p-toluenesulfonyl)-N-(3-p-toluenesulfonyl-oxy-phenyl)urea with an X-ray diffraction pattern with Bragg angles (2?/CuK.sub.?) of 10.3, 11.0, 12.9, 13.2, 15.4, 17.1, 18.0, 18.2, 19.4, 20.0, 20.7, 21.2, 23.0, 24.9, 25.3, 26.5, 26.8, 27.5, 30.7, 32.7 as a colour developer in a heat-sensitive recording material comprising a carrier substrate, a heat-sensitive colour-forming layer which is applied to one face of the carrier substrate and which contains at least one non-phenolic colour developer and at least one colour former, and an adhesive layer and/or a coating in order to allow rear-face printing using conventional printing methods on the carrier substrate face facing away from the heat-sensitive colour-forming layer, so as to limit the loss of image density and/or the relative print contrast and/or the reduction of the area-based colour developer quantity, wherein, with a value of ?1.20 optical density units for the heat-sensitive recording material stored in accordance with the migration test defined in the description, the image density equals at least 35% of the value of the image density prior to storage and/or the relative print contrast of the heat-sensitive recording material stored in accordance with the migration test equals at least 70% of the value of the relative print contrast prior to storage and/or the area-based colour developer quantity of the heat-sensitive recording material stored in accordance with the migration test equals at least 30% of the area-based colour developer quantity prior to storage.

Use of N-(p-toluenesulfonyl)-N-(3-p-toluenesulfonyl-oxy-phenyl)urea with an X-ray diffraction pattern with Bragg angles (2?/CuK.sub.?) of 10.3, 11.0, 12.9, 13.2, 15.4, 17.1, 18.0, 18.2, 19.4, 20.0, 20.7, 21.2, 23.0, 24.9, 25.3, 26.5, 26.8, 27.5, 30.7, 32.7 as a colour developer in a heat-sensitive recording material comprising a carrier substrate, a heat-sensitive colour-forming layer which is applied to one face of the carrier substrate and which contains at least one non-phenolic colour developer and at least one colour former, and an adhesive layer and/or a coating in order to allow rear-face printing using conventional printing methods on the carrier substrate face facing away from the heat-sensitive colour-forming layer, so as to limit the loss of image density and/or the relative print contrast and/or the reduction of the area-based colour developer quantity, wherein, with a value of ?1.20 optical density units for the heat-sensitive recording material stored in accordance with the migration test defined in the description, the image density equals at least 35% of the value of the image density prior to storage and/or the relative print contrast of the heat-sensitive recording material stored in accordance with the migration test equals at least 70% of the value of the relative print contrast prior to storage and/or the area-based colour developer quantity of the heat-sensitive recording material stored in accordance with the migration test equals at least 30% of the area-based colour developer quantity prior to storage.

The present invention provides a heat-sensitive recording body that is excellent in high-speed recording properties, that makes it possible to perform high-quality image recording with a high sensitivity even at a low thermal energy, and that is excellent in printability and economy. A heat-sensitive recording body containing a support, an intermediate layer, and a heat-sensitive color forming layer comprising as main components a leuco dye and a developer, the intermediate layer and the heat-sensitive color forming layer stacked on the support in the order as mentioned, wherein the intermediate layer contains a hollow particle containing a hollow core portion formed by drying a solvent for an alkali-swellable aqueous gel comprising a (meth)acrylic-based copolymer having an acid value of 200 to 400 mgKOH/g, and a resin portion encapsulating the core portion and having a non-alkali-swellable outermost layer of the particle, the non-alkali-swellable outermost layer formed using a hydrophobic monomer, and the hollow particle has an average particle diameter of 1.5 to 3.5 m and a percentage of hollowness of 60 to 85%.

A fiber assembly according to one embodiment of the present disclosure includes a fiber. The fiber includes a core part that contains a coloring compound, a photothermal conversion material, and a color developer/reducer, and a sheath part that covers the core part and has a heat-insulating property.

A fiber assembly according to one embodiment of the present disclosure includes a fiber. The fiber includes a core part that contains a coloring compound, a photothermal conversion material, and a color developer/reducer, and a sheath part that covers the core part and has a heat-insulating property.

A method of imparting color to a plastic substrate comprising applying to the substrate, or incorporating within the substrate, a diacetylene compound of general formula (I) wherein n=1 to 20; R.sup.1=an optionally substituted C.sub.1-20 alkyl group which may contain heteroatoms; T=H, an optionally substituted C.sub.1-20 alkyl group which may contain heteroatoms or (CH.sub.2).sub.mC(O)-Q.sup.2R.sup.2; Q.sup.1=NH, CO, NHCONH, OCONH, COS, NHCSNH or NR.sup.3, wherein m, Q.sup.2 and R.sup.2 are independently selected from the same groups as n, Q.sup.1 and R.sup.1 respectively; R.sup.3 is an optionally substituted C.sub.1-20 alkyl group which may contain heteroatoms; and irradiating the substrate to impart color to the substrate is described.

A method of imparting color to a plastic substrate comprising applying to the substrate, or incorporating within the substrate, a diacetylene compound of general formula (I) wherein n=1 to 20; R.sup.1=an optionally substituted C.sub.1-20 alkyl group which may contain heteroatoms; T=H, an optionally substituted C.sub.1-20 alkyl group which may contain heteroatoms or (CH.sub.2).sub.mC(O)-Q.sup.2R.sup.2; Q.sup.1=NH, CO, NHCONH, OCONH, COS, NHCSNH or NR.sup.3, wherein m, Q.sup.2 and R.sup.2 are independently selected from the same groups as n, Q.sup.1 and R.sup.1 respectively; R.sup.3 is an optionally substituted C.sub.1-20 alkyl group which may contain heteroatoms; and irradiating the substrate to impart color to the substrate is described.

A method of producing a security document includes the steps of producing a first part of a color image by color laser marking a security document precursor; and producing a second part of the color image by a second imaging technique different from laser marking. The resulting security document is more difficult to falsify.

Disclosed and claimed herein is a thermosensitive recording medium, having a base sheet; a binder; and a thermosensitive material on at least one surface of the base sheet comprising: one or more oxidizing agents; and a dye precursor.

Disclosed and claimed herein is a thermosensitive recording medium, having a base sheet; a binder; and a thermosensitive material on at least one surface of the base sheet comprising: one or more oxidizing agents; and a dye precursor.