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AssigneeKabushiki Kaisha Toshiba
InventorsSatoshi Takayama, Sawako Fujioka, Tetsuo Okuyama, Hideyuki Nishizawa, Hirohisa Miyamoto, Masami Sugiuchi
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A reversible thermal recording medium comprises a composition containing a color former, a developer, a reversible material capable of reversibly changing the state of the composition by supplying heat energies with two different values, and, as required, a phase separation controller which permits changing the phase separation speed of the developer at temperatures in the vicinity of the melting point of the phase separation controller, at least 80% by weight of the reversible material being a sterol compound in which the carbon-to-carbon bond between 2- and 3-positions of the stroid skeleton is a single bond, the carbon-to-carbon bond between 3- and 4-positions of the steroid skeleton is a single bond, a hydroxyl group is attached to the carbon atom in at least the 3-position of the steroid skeleton, and a specified chemical structure is bonded at 16- and 17-positions of the stroid skeleton, and the phase separation controller being provided by a low molecular organic material, the maximum carbon chain length there of being at least 10.
A reversible thermal recording medium, comprising a composition containing a color former, a developer, and a reversible material capable of reversibly changing the state of said composition by supplying heat energies with two different values or by providing two different heat histories, at least 80% by weight of said reversible material being a sterol compound in which the carbon-to-carbon bond between 2- and 3-positions of the steroid skeleton represented by structural formula (1) given below is a single bond, the carbon-to-carbon bond between 3- and 4-positions of said steroid skeleton is a single bond, a hydroxyl group is attached to the carbon atom in at least the 3-position of the steroid skeleton, and at least one of chemical structures (A) to (D) given below is bonded at 16- and 17-positions of the steroid skeleton:
A reversible thermal recording medium, comprising a composition consisting of a color former, a developer and a phase separation controller which permits changing the phase separation speed of said color former or said developer at temperatures in the vicinity of the melting point of said phase separation controller, said phase separation controller being highly crystallizable, having a low molecular weight and comprising a long-chained alkyl group having a minimum carbon chain length of 10 and at least one polar group.
A reversible thermal recording medium, comprising a composition containing a color former, a developer, and a reversible material, said reversible material being provided by a benzophenone compound represented by general formula (2) given below:
A reversible thermal recording medium, comprising a composition containing a color former, a developer provided by a benzophenone compound having a phenolic hydroxyl group, a reversible material provided by a steroid compound in which the carbon-to-carbon bond between 2- and 3-positions of the steroid skeleton is a single bond, the carbon-to-carbon bond between 3- and 4-positions of said steroid skeleton is a single bond, and both a hydroxyl group and a --OCOCH.sub.3 group are attached to the carbon atom in the 3-position of the steroid skeleton, and
A reversible thermal recording medium, comprising a composition consisting of a color former, a developer, a reversible material, and a phase separation controller, the difference between the melting point and the solidifying point of said phase separation controller being at least 10.degree. C.,
Dependencies are inferred from the claim text.