Reversible heat-sensitive recording medium

• US 5,679,615 A
• Filed: 09/13/1995
• Issued: 10/21/1997
• Est. Priority Date: 09/13/1994
• Status: Expired due to Fees

• Current Assignee: Tomoegawa Paper Company Limited
• Original Assignee: Tomoegawa Paper Company Limited
• Inventors: Tanaka, Kenichi, Matsumoto, Tatsuru
• Primary Examiner(s): Hess, Bruce H.
• Application Number:
  US08/527,516
• Time in Patent Office: 769 Days
• Field of Search: 503/201, 503/216, 503/217, 503/226, 503/200, 503/209, 503/214, 427/150-152
• US Class Current: 503/217
• CPC Class Codes: B41M 5/3333 Non-macromolecular compounds

Abstract

A reversible heat-sensitive recording medium which includes at least a support and formed thereon a heat-sensitive recording layer including at least the following components: an electron-donating color-forming compound having a lactone ring, (b) an electron-accepting compound having a phenolic hydroxyl group, (c) at least one organic compound selected from compounds represented by formulae (I) to (V), and (d) a thermoplastic resin having an erasing action. The content of the thermoplastic resin having an erasing action is being from 15 to 70% by weight based on the total amount of components (a) to (d) Formulae (I) to (V) are as follows:

R.sub.1 --CO--N(R.sub.2)R.sub.3                            (I)

R.sub.1 --CO--NH--R.sub.4 --NH--CO--R.sub.2                (II)

R.sub.1 --CO--O--R.sub.2                                   (III)

R.sub.1 --NH--CO--NH--R.sub.2                              (IV)

R.sub.1 --CO--R.sub.2                                      (V)

wherein R₁ represents an alkyl group, an aryl group, an alkenyl group, or a hydroxyalkyl group; R₂ and R₃ each represents a hydrogen atom, an alkyl group, an aryl group, a hydroxyalkyl group, or an alkenyl group; and R₄ represents an alkylene group. This reversible heat-sensitive recording medium can be easily colored and erased by means of heat energy control.

Claims

1. A reversible heat-sensitive recording medium which comprises:

a support;

a heat-sensitive recording layer formed on the support and comprising components (a) an electron-donating color-forming compound having a lactone ring, (b) an electron-accepting compound having a phenolic hydroxyl group, (c) at least one organic compound selected from compounds represented by formulae (I) to (V), and (d) a thermoplastic resin having an erasing action, the content of the thermoplastic resin having an erasing action being from 15 to 70% by weight based on the total amount of the components (a) to (d);

a protective layer formulated from an ultraviolet-curing or electron beam-curing resin; and

an interlayer disposed between the protective layer and the heat-sensitive recording layer, the interlayer comprising at least one resin selected from the group consisting of an acrylic-silicone copolymer, an ester-silicone copolymer, and an acrylic-modified silicone resin,

wherein the formulae (I) to (V) are as follows;

space="preserve" listing-type="equation">R.sub.1 -CO--N(R.sub.2)R.sub.3 (I)

space="preserve" listing-type="equation">R.sub.1 --CO--NH--R.sub.4 ----NH--CO--R.sub.2 (II)

space="preserve" listing-type="equation">R.sub.1 --CO--O--R.sub.2 (III)

space="preserve" listing-type="equation">R.sub.1 --NH--CO--NH--R.sub.2 (IV)

space="preserve" listing-type="equation">R.sub.1 --CO--R.sub.2 (V)

wherein R₁ represents an alkyl group, an aryl group, an alkenyl group, or a hydroxyalkyl group;

R₂ and R₃ each represents a hydrogen atom, an alkyl group, an aryl group, a hydroxyalkyl group, or an alkenyl group; and

R₄ represents an alkylene group.

2. The reversible heat-sensitive recording medium of claim 1, wherein the thermoplastic resin having an erasing action is capable of coming into a compatibilized state with the at least one organic compound selected from compounds represented by formulae (I) to (V), at a temperature in the range of from the melting point of the organic compound to 200°

C.

3. The reversible heat-sensitive recording medium of claim 1, wherein the thermoplastic resin having an erasing action is a hydrophobic resin having a glass transition temperature of from 30°

to 110°

C. and having a rubber-like elasticity region at temperatures not lower than the glass transition temperature.

4. The reversible heat-sensitive recording medium of claim 1, wherein the at least one organic compound is selected from the compounds of formulae (I) to (V) where R₁ contains from 8 to 30 carbon atoms, has a melting point higher than 58°

C., and is added in an amount of 20% by weight or higher based on the total amount of components (a) to (d).

5. A reversible heat-sensitive recording medium which comprises:

a support;

a heat-sensitive recording layer formed on the support and comprising components (a) an electron-donating color-forming compound having a lactone ring, (b) an electron-accepting compound having a phenolic hydroxyl group, (c) at least one organic compound selected from compounds represented by formulae (I) to (V), and (d) a thermoplastic resin having an erasing action, the content of the thermoplastic resin having an erasing action being from 15 to 70% by weight based on the total amount of the components (a) to (d);

a protective layer formulated from an ultraviolet-curing or electron beam-curing resin; and

an interlayer disposed between the protective layer and the heat-sensitive recording layer, the interlayer comprising at least one resin selected from the group consisting of an acrylic-silicone copolymer, an ester-silicone copolymer, and an acrylic-modified silicone resin,

wherein the formulae (I) to (V) are as follows;

space="preserve" listing-type="equation">R.sub.1 --CO--N(R.sub.2)R.sub.3 (I)

space="preserve" listing-type="equation">R.sub.1 --CO--NH--R.sub.4 ----NH--CO--R.sub.2 (II)

space="preserve" listing-type="equation">R.sub.1 --CO--O--R.sub.2 (III)

space="preserve" listing-type="equation">R.sub.1 --NH--CO--NH--R.sub.2 (IV)

space="preserve" listing-type="equation">R.sub.1 --CO--R.sub.2 (V)

wherein R₁ represents an alkyl group, an aryl group, an alkenyl group, or a hydroxyalkyl group;

R₂ and R₃ each represents a hydrogen atom, an alkyl group, an aryl group, a hydroxyalkyl group, or an alkenyl group; and

R₄ represents an alkylene group,

and further wherein the heat-sensitive recording layer has a color-developing temperature at which a color is developed upon heating and has two erasing temperatures at which the color is removed upon heating, one of the erasing temperatures being lower than the color-developing temperature and the other being higher than the color-developing temperature.

6. A reversible heat-sensitive recording medium which comprises:

a support;

a heat-sensitive recording layer formed on the support and comprising components (a) an electron-donating color-forming compound having a lactone ring, (b) an electron-accepting compound having a phenolic hydroxyl group, (c) at least one organic compound selected from compounds represented by formulae (I) to (V), and (d) a thermoplastic resin having an erasing action, the content of the thermoplastic resin having an erasing action being from 15 to 70% by weight based on the total amount of the components (a) to (d),

wherein the formulae (I) to (V) are as follows;

space="preserve" listing-type="equation">R.sub.1 --CO--N(R.sub.2)R.sub.3 (I)

space="preserve" listing-type="equation">R.sub.1 --CO--NH--R.sub.4 ----NH--CO--R.sub.2 (II)

space="preserve" listing-type="equation">R.sub.1 --CO--O--R.sub.2 (III)

space="preserve" listing-type="equation">R.sub.1 --NH--CO--NH--R.sub.2 (IV)

space="preserve" listing-type="equation">R.sub.1 --CO--R.sub.2 (V)

wherein R₁ represents an alkyl group, an aryl group, an alkenyl group, or a hydroxyalkyl group;

R₂ and R₃ each represents a hydrogen atom, an alkyl group, an aryl group, a hydroxyalkyl group, or an alkenyl group; and

R₄ represents an alkylene group, and

wherein the heat-sensitive recording layer is capable of exhibiting an erased state at room temperature and a colored state at room temperature and is reversibly convertible between the erased state and the colored state by thermal treatment, the heat-sensitive recording layer being adapted to undergo a first transition from the colored state to the erased state by heating the heat-sensitive recording layer from room temperature to a first temperature range that is higher than room temperature and thereafter cooling the heat-sensitive recording layer to below the first temperature range, the heat-sensitive recording layer being adapted to undergo a second transition from the erased state to the colored state by heating the heat-sensitive recording layer from room temperature to a second temperature range that is higher than the first temperature range and thereafter cooling the heat-sensitive recording layer to below the first temperature range, and the heat sensitive recording layer being adapted to undergo a third transition from the colored state to the erased state by heating the heat-sensitive recording layer from room temperature to a third temperature range that is higher than the second temperature range and thereafter cooling the heat-sensitive recording layer to below the first temperature range.

7. The reversible heat-sensitive recording medium of claim 6, wherein the thermoplastic resin having an erasing action is capable of coming into a compatibilized state with the at least one organic compound selected from the compounds represented by formulae (I) to (V), at a temperature in the range of from the melting point of the organic compound to 200°

C.

8. The reversible heat-sensitive recording medium of claim 6, wherein the thermoplastic resin having an erasing action is a hydrophobic resin having a glass transition temperature of from 30°

to 110°

C. and having a rubber-like plasticity region at temperatures not lower than the glass transition temperature.

9. The reversible heat-sensitive recording medium of claim 6, wherein the at least one organic compound is selected from the compounds of formulae (I) to (V) where R₁ contains from 8 to 30 carbon atoms, has a melting point higher than 58°

C., and is added in an amount of 20% by weight or higher based on the total amount of components (a) to (d).

10. The reversible heat-sensitive recording medium of claim 6, further comprising:

a protective layer formulated from an ultraviolet-curing or electron beam-curing resin; and

an interlayer disposed between the protective layer and the heat-sensitive recording layer, the interlayer comprising at least one resin selected from the group consisting of an acrylic-silicone copolymer, an ester-silicone copolymer, and an acrylic-modified silicone resin.