There is disclosed a heat-sensitive recording material including an undercoat layer formed on one surface of a support and a heat-sensitive recording layer formed on the undercoat layer. The heat-sensitive recording layer contains a leuco dye and a coloring agent. The undercoat layer contains hollow particles and a binding resin. A maximum particle diameter (D100) of the hollow particles is 10 to 30 μm. A particle diameter (D50) of the hollow particles at cumulative 50 volume % is 4.0 to 15 μm. A ratio D100/D50 of the maximum particle diameter (D100) of the hollow particles to the particle diameter (D50) of the hollow particles at cumulative 50 volume % is 1.8 to 3.0. A volume percentage of the hollow particles having particle diameters of 2.0 μm or less is 1% or less.

There is disclosed a heat-sensitive recording material including an undercoat layer formed on one surface of a support and a heat-sensitive recording layer formed on the undercoat layer. The heat-sensitive recording layer contains a leuco dye and a coloring agent. The undercoat layer contains hollow particles and a binding resin. A maximum particle diameter (D100) of the hollow particles is 10 to 30 μm. A particle diameter (D50) of the hollow particles at cumulative 50 volume % is 4.0 to 15 μm. A ratio D100/D50 of the maximum particle diameter (D100) of the hollow particles to the particle diameter (D50) of the hollow particles at cumulative 50 volume % is 1.8 to 3.0. A volume percentage of the hollow particles having particle diameters of 2.0 μm or less is 1% or less.

Hollow resin particles for thermosensitive recording media containing a thermoplastic resin shell and a hollow part surrounded by the shell. The hollow resin particles contain a thermally-vaporizable hydrocarbon in an encapsulation ratio of at least 0.2 wt %. The hollow resin particles preferably have a mean volume particle size ranging from 0.1 to 10 μm.

Color change compositions that transition from a first to second color state upon application of an applied stimulus are provided. Also provided are substrates having the compositions on a surface thereof, as well as methods of making and using the compositions.

Color change compositions that transition from a first to second color state upon application of an applied stimulus are provided. Also provided are substrates having the compositions on a surface thereof, as well as methods of making and using the compositions.

An erasing unit according to an embodiment of the present disclosure is a unit that performs erasing of information written on a reversible recording medium. This erasing unit includes: a light source section including one or a plurality of laser devices; and a controller that controls the light source section to cause the light source section to emit a smaller number of laser light beams having emission wavelengths than the number of the recording layers included in the reversible recording medium.

The present invention relates to an N,N′-diurea derivative represented by the following general formula (1) and a method for producing the same. In addition, the present invention relates to a thermosensitive recording material in which a thermosensitive recording layer including a basic dye which is colorless or lightly colored at room temperature and a developer capable of developing color upon contact with the basic dye by heating is provided on a base sheet, wherein the developer is the N,N′-diurea derivative represented by the following general formula (1):

##STR00001##

(wherein R2 is an alkyl group, an aralkyl group, or an aryl group; and A1 is a hydrogen atom or an alkyl group).

The present invention relates to an N,N′-diurea derivative represented by the following general formula (1) and a method for producing the same. In addition, the present invention relates to a thermosensitive recording material in which a thermosensitive recording layer including a basic dye which is colorless or lightly colored at room temperature and a developer capable of developing color upon contact with the basic dye by heating is provided on a base sheet, wherein the developer is the N,N′-diurea derivative represented by the following general formula (1):

##STR00001##

(wherein R2 is an alkyl group, an aralkyl group, or an aryl group; and A1 is a hydrogen atom or an alkyl group).

A heat-sensitive recording material including a substrate, a heat-sensitive recording layer which includes N-(4-methylphenylsulfonyl)-/V-(3-(4-methylphenylsulfonyloxy)pheny-purea and/or N42-(3-phenylureido)phenyl]benzol sulfonamide, and an intermediate layer which is arranged between the substrate and the heat-sensitive recording layer and which includes calcined aluminum silicate, and a method for producing a heat-sensitive recording material and to the use of calcined aluminum silicate in an intermediate layer of a heat-sensitive recording material.

An information medium according to an embodiment of the present disclosure includes two or more data layers provided on a support base. The two or more data layers have two or more pieces of visible information recorded on the two or more data layers. The two or more pieces of visible information are obtained by decomposing two-dimensional visible information and thereby allowing synthesis of the two or more pieces of visible information to result in the two-dimensional visible information.