JPH09176627A - Reversible thermochromic recording material and reversible thermochromic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible thermochromic recording material which is not degraded even when the color developing and fading are repeated and hence can be repeatedly used as recording paper and to provide a recording medium using the same. SOLUTION: This reversible thermochromic recording material, capable of repeating color developing and fading when heated repeatedly to the color developing and fading temps., at least contains 1 pt.wt. electron-accepting phenol compd. 0.1-0.6 pt.wt. electron-donating color-developing compd. and 0.01-0.09 pt.wt. polymer for controlling the color developing and fading which is always compatible with the color-developing compd. is compatible with the phenol compd. in some temp. range and incompatible in another some temp. range, and has a glass transition temperature equal or lower than that of the phenol compd. The color fading temp. range is at the lower side than the color developing temp. range. A recording medium using the material is also provided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a reversible thermochromic recording material and a reversible thermochromic recording medium.
More specifically, it is a reversible thermochromic recording material comprising at least a color development / erasing control polymer, an electron-accepting phenol compound, and an electron-donating color-forming compound, and a reversible thermochromic recording medium using this recording material. Heating to temperature range,
By heating to the erasing temperature range lower than the coloring temperature range,
The present invention relates to a reversible thermochromic recording material which can reversibly and repeatedly obtain a colored state and a decolored state, and a reversible thermochromic recording medium having a support made of a layer comprising the recording material.

[0002]

2. Description of the Related Art It is well known that a colorless or light-colored electron-donating color-forming compound reacts with an electron-donating compound to irreversibly develop a color. There are pressure-sensitive papers and thermal papers as recording papers to which this principle is applied.As pressure-sensitive papers, a leuco dye solution, which is an electron-donating color-developing compound, is encapsulated in microcapsules and coated with a binder. , A pre-accepting compound such as bisphenol A is used in combination with a base paper coated with a binder or the like, the microcapsules are destroyed by an external pressure, and the electron-donating compound and the electron-accepting compound are melt-reacted, There are things that utilize coloring. As the thermal paper, fine powder of leuco dye, bisphenol A, sensitizer, storage stabilizer, etc. is applied together with a binder, and it is used that is colored by the heat supplied from the head of the thermal printer. is there. For example, there is Japanese Examined Patent Publication No. 43-7600. However, with pressure-sensitive paper and thermal paper having the above-mentioned configuration,
The used recording paper is not erased and reused as recording paper. In recent years, from the viewpoint of resource saving,
Alternatively, from the viewpoint of convenience, technical development for thermally and reversibly performing color development and color erasure has been energetically carried out. For example,
A thermochromic composition using a leuco dye which is an electron-donating color developing compound and a phenol which is an electron-accepting compound is described in, for example, US Pat. No. 3,560,229.

In addition, it comprises (a) an electron-donating color-forming compound, (b) an electron-accepting compound and (c) a reaction temperature adjusting solvent. The color is selected by the component (a) and the color is selected by the component (b). A reversible thermochromic composition in which the color density is selected and the coloration temperature is determined by the component (c) and a composition in which this composition is contained in microcapsules are disclosed in, for example, JP-B-51-44706. -44707, Japanese Patent Publication No. 51-44708, and the like. Also, JP-A-58-1911
90, JP-A-60-257289, JP-B-4-30355, and JP-B-4-30916, electron-donating color-forming compounds, electron-accepting compounds such as gallic acid or phloroglucinol. There is disclosed a reversible recording medium in which a recording layer made of a binder such as cellulose acetate is provided on a substrate, an image is formed by heat, and an image can be erased by water or steam. However, since these recording media erase the image with water or water vapor, the formed image is easily affected by moisture or water, and there is a problem in image stability. Japanese Patent Application Laid-Open No. 63-315287 discloses that
A compound having a lactone ring as an electron-donating color-forming compound and a compatibilizer consisting of an alkylphenol that is liquid at room temperature as an electron-accepting compound are used by encapsulating them in glass or microcapsules without using a binder and heating. And a material that reversibly develops decoloration and color development by cooling. Contrary to the reversible thermochromic recording material of the present invention, this material is colorless and transparent when heated and loses fluidity when cooled to develop color. However, since it has no hysteresis property, it cannot hold a record and is not suitable as a recording medium. Further, a proposal of a reversible thermosensitive recording material comprising a leuco dye, an amphoteric compound having a functional group capable of coloring or erasing by reacting with the dye, and a polymer binder is disclosed in JP-A-5-254244, Japanese Patent Laid-Open No. 5-262032, Japanese Patent Laid-Open No. 6-48028, Japanese Patent Laid-Open No. 2-188293, Japanese Patent Laid-Open No. 2-18
8294, International Publication No. WO90 / 11898,
JP-A-4-46986, JP-A-4-303680
JP-A-4-50289, JP-A-4-50
It is disclosed in Japanese Patent Application Publication No. 290, Japanese Patent Application Laid-Open No. 5-177931 and the like. More specifically, JP-A-5-254
Japanese Patent No. 244 discloses a heat-sensitive recording material composed of a complex of gallic acid and 3-methoxypropylamine, which is an amphoteric compound having a functional group relating to color development or decolorization, and crystal violet lactone and a polyvinyl alcohol binder. . International publication number WO90 / 11898
Discloses a thermosensitive recording material comprising a compound having at least one of a phenolic hydroxyl group or a carboxyl group and having an amino group as a functional group, and crystal violet lactone and a methacrylic resin binder. Further, JP-A-6-210954 discloses a leuco dye and a phenolic electron-accepting compound that reversibly changes the leuco dye between a colored state and a decolorized state, for example, 4'-hydroxy-n-heptaneanilide. A reversible thermosensitive material consisting of is disclosed. However, these reversible thermosensitive recording materials are difficult to control the temperature of coloring and decoloring because the coloring and decoloring actions occur competitively.
In addition, there are problems that the image contrast is poor, and that the material is deteriorated because the color is erased at a high temperature, and the number of times of repeated use is reduced. JP-A-5-124360 discloses a combination of an electron-donating color-forming compound and an electron-accepting compound selected from organic phosphoric acid compounds having a long-chain alkyl group, aliphatic carboxylic acid compounds, and phenol compounds. Discloses a means for selecting a reversible thermochromic composition. It is said that when the composition is heated to a color development temperature range, both compounds melt and react to cause ring-opening of the color-forming compound to develop color, and by rapidly cooling the compound, the color development state can be maintained even at room temperature. There is. Then, when the colored composition is heated to a decoloring temperature range lower than the coloring temperature range, the long-chain alkyl group of the electron-accepting compound agglomerates, and the electron-accepting compound becomes a single crystal, and from the color-forming material. It is presumed that they will separate and as a result will disappear. That is, in the relationship between the electron-donating color-forming compound and the electron-accepting compound, the two compounds are maintained in a reacted state and are solidified to maintain a color-developed state. It is said that it separates and crystallizes under the conditions to form a single crystal and maintains the decolored state. But,
In the reversible thermochromic recording material using this principle, the electron-accepting compound that can be used is limited to those having a long-chain alkyl group. When such a color-forming composition is used as a recording medium or a display medium, a recording layer composed of the composition and a polymer binder is formed on a support in many cases. Since the decoloring property is greatly influenced by the polymer binder, a practical product cannot be obtained without the limitation of the polymer binder. Further, there is a drawback that the decoloring property is not good.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a thermosensitive recording capable of reversibly developing and erasing color by using an electron-donating color-forming compound and an electron-accepting compound and heating at a color-forming temperature and a color-erasing temperature. By using a special coloring and decoloring control polymer in the material and specifying the ratio of each component, the above problems are solved, and a coloring state of a practical concentration can be obtained by heating to the coloring temperature range, and at room temperature. When cooled, the color development state can be maintained for a long period of time or for a desired period, and it can be decolored by heating to a decolorization temperature range lower than the color development temperature range. The object is to obtain a reversible thermochromic recording material capable of maintaining a decolored state and a reversible thermochromic recording medium using the same.

[0005]

As a result of various studies, the inventors of the present invention have found that, in order to obtain the reversible thermochromic recording material, an electron-donating color-forming compound and an electron-accepting compound are contained in a polymer matrix. If this polymer is held and the color-forming compound and the electron-accepting compound are controlled to be in a compatible state or an incompatible state according to thermal conditions, a desired reversible thermochromic recording material can be obtained. I got the knowledge. That is, it was clarified that the problem could be solved by developing a matrix polymer that holds an electron-donating color-forming compound and an electron-accepting compound and controls the compatible state of both. As a result of earnest research on many combinations of an electron-donating color-developing compound, an electron-accepting compound and a color development / erasing control polymer, the present inventors have used a phenol compound as the electron-accepting compound, and have developed a color development / erasing control polymer: The compounding ratio of the electron-accepting phenol compound and the electron-donating compound is 1: 0.1 by weight.
.About.0.6: 0.01 to 0.09, the electron-accepting phenol compound is compatible with the polymer when heated to a coloring temperature range, for example, 90.degree. C. or higher, and is particularly related to the temperature range. Reacts with an electron-donating color-forming compound that is in a compatible state to exhibit a color-developed state, and can maintain that color-developed state even when cooled to room temperature. For example, when heated to 40 ℃ ~ 70 ℃,
The electron-accepting phenol compound becomes incompatible with the above-mentioned polymer, the bond with the electron-donating color-developing compound in the reaction state is broken accordingly, and a decolored state is obtained, which is cooled to room temperature. The present invention has been completed by finding that the decolored state can be maintained.

The present invention provides "1. A reversible thermochromic recording material capable of repeating coloring and decoloring by heating to a coloring temperature and a decoloring temperature, at least a. The electron-donating color-forming compound and the electron-donating color-forming compound have a temperature range in which they are always compatible with each other and an electron-accepting phenol compound is in a temperature range in which they are incompatible with each other. It is composed of a color development / decoloration control polymer having a glass transition temperature lower than the melting point of the phenol compound, and the compounding ratio of the color development / decoloration control polymer: electron-accepting phenol compound: electron-donating coloration compound is 1: 0 by weight. .1 to 0.6: 0.0
A reversible thermochromic recording material having a decoloring temperature range of 1 to 0.09 and a decoloring temperature range lower than a coloring temperature range. 2. The reversible thermochromic recording material as described in 1 above, wherein the color development / erasing control polymer has a glass transition temperature of 60 ° C. or lower. 3. The reversible thermochromic recording material according to item 1 or 2, wherein the color development / erasing control polymer is one or more polymers selected from styrene polymers and diene polymers. 4. The styrene-based polymer is polystyrene, styrene-butadiene copolymer, styrene-isoprene-
Styrene copolymer, styrene-epoxy modified styrene copolymer, styrene-acrylic ester copolymer,
Styrene-methacrylic ester copolymer, styrene-
Ethylene-butadiene-styrene copolymer, styrene-ethylene-propylene-styrene copolymer, styrene-polymethylmethacrylate graft polymer, epoxy-modified polystyrene-polymethylmethacrylate graft polymer, acid-modified acrylic-polystyrene graft polymer, epoxy-modified polystyrene-polystyrene graft The reversible thermochromic recording material according to item 3, which is one or more polymers selected from the group consisting of polymers and polybutylene terephthalate-polystyrene graft polymers. 5. The reversible thermochromic recording material according to item 3, wherein the diene polymer is one or more polymers selected from butadiene polymers and isoprene polymers. 6. The reversible thermochromic recording material according to any one of items 1 to 5, wherein the electron-accepting phenol compound is a gallic acid ester. 7. The electron-accepting phenol compound has the general formula

[0007]

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1 to 6 which is a gallic acid ester represented by the formula (wherein R is a C ₃ or higher alkyl group).
The reversible thermochromic recording material according to any one of items. 8. A reversible thermochromic recording medium comprising a reversible thermochromic recording layer comprising the reversible thermochromic recording material according to any one of items 1 to 7 on a support. 9. Item 9. The reversible thermochromic recording medium according to item 8, wherein an undercoat layer for improving adhesion is provided between the reversible thermochromic recording layer and the support. 10. A protective layer is provided on the reversible thermochromic recording layer,
The reversible thermochromic recording medium according to item 8 or 9. 11. Item 10. The reversible thermochromic recording medium according to Item 10, wherein the protective layer is made of a transparent polymer. 12. Item 12. The reversible thermochromic recording medium according to any one of items 8 to 11, which comprises a colorant in the reversible thermochromic recording medium. 13. 13. The reversible thermochromic recording layer of a single color or a plurality of colors, which is composed of the reversible thermochromic recording material, is formed on a support in a predetermined character, figure or pattern, and any one of items 8 to 12 above. The reversible thermochromic recording medium described in 1. 14． A reversible thermochromic recording layer of a single color or a plurality of colors composed of a reversible thermochromic recording material is formed by being laminated on all or part of a support on which predetermined characters, figures or patterns have been formed in advance. Item 12. The reversible thermochromic recording medium according to any one of items 1 to 12. ".

The reversible thermochromic recording material of the present invention is characterized by having a hysteresis property. When the recording material of the present invention is heated from the initial colorless state, the temperature rises in the colorless state, and when it reaches the coloring temperature range, it develops color. Then, when the temperature is lowered, it is cooled in the colored state, and even when the temperature reaches an initial colorless state, for example, room temperature, the colored state is maintained and the color is not immediately erased. To erase the color, it is necessary to heat it to the color removal temperature and return it to the initial color development path. That is, in order to bring the color-developed state into the color-erased state, the initial color-erased state can be obtained by heating in a color-erasing temperature range lower than the color-developing temperature and cooling. In other words, the path from colorless to colored and the path from colored to colorless are different, and have a hysteresis property. Since there is such a hysteresis property, it is possible to save the recorded color. Of course, depending on the compound and composition, there are differences in the decoloring temperature and the coloring temperature, and the temperature range of the coloring start temperature and the coloring saturation temperature in the color change path, etc., but the recording materials of the present invention are all characterized by having a hysteresis property, which is clear. You can get a good record.

The electron-donating color-developing compound used in the present invention is a colorless or light-colored dye used as a pressure-sensitive / heat-sensitive dye, and includes triphenylmethanephthalide dye, fluorane dye, indolylphthalide dye, There are spiropyran dyes, rhodamine lactam dyes, triphenylmethane dyes, azaphthalide dyes and azomethine dyes. Specific examples are shown below, but the compounds are not limited to these as long as they are always compatible with the color development / erasing control polymer. 3-diethylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7- (2-chlorophenyl) aminofluorane, 3
-Diethylamino-7- (2-bromophenyl) aminofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6-methyl-7
-(3-Trifluoromethylphenyl) aminofluorane, 3-diethylamino-7-chlorofluorane, 3-
Diethylamino-7-bromofluorane, 3-diethylamino-7-piperidinofluorane, 3-diethylamino-7- (N-ethyl-N-phenyl) aminofluorane, 3-diethylamino-7,8-benzofluorane ,
3-diethylamino-6-chloro-7- (2,3-dicyclohexylphenyl) aminofluorane, 3-diethylamino-6-chloro-7-phenylaminofluorane, 3-diethylamino-6-methyl-7- (2. 4-
Dimethylphenyl) aminofluorane, 3-diethylamino-6-chloro-7- (3-trifluoromethylphenyl) aminofluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7- (3-trifluoromethylphenyl) aminofluorane, 3-dipropylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7- (3-trichloromethylphenyl) aminofluorane, 3-diethylamino-7 -(2-Methoxycarbonylphenyl)
Aminofluorane, 3-diallylamino-7,8-benzofluorane, 3-diethylamino-5-chloro-7-
(N-α-phenylethyl) aminofluorane, 3-diethylamino-5-methyl-7- (N-phenylethyl) aminofluorane, 3-diethylamino-5-methyl-7-dibenzylaminofluorane, 3- Diethylamino-7-medoxyfluorane, 3-diethylamino-
6-diethylaminofluorane, 3-diethylamino-
7- (p-toluidino) fluorane, 3-diethylamino-5-chloro-7- {N-benzyl-N- (trifluoromethylphenyl)} aminofluorane, 3-dibutylamino-7- (2-chlorophenyl) amino Fluorane, 3-diethylamino-7-acetaminofluorane, 3-dibutylamino-6-chloro-7-ethoxyethylaminofluorane, 3-dibutylamino-7- (2
-Fluorophenyl) aminofluorane, 3-dibutylamino-7,8-benzofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-dibutylamino-6-methyl-7-phenylaminofluorane, 3- Dimethylamino-5,7-dimethylfluorane, 3-cyclohexylamino-6-chlorofluorane, 3-cyclohexylamino-6-bromofluorane, 3-cyclohexylamino-6-chloro-7- (2-chlorophenyl) amino Fluorane, 3- (N-methyl-N-cyclohexyl) amino-7,8-benzofluorane, 3-
(N-Ethyl-Nn-octyl) amino-7,8-benzofluorane, 3- (N-ethyl-N-i-amyl)
Amino-7,8-benzofluorane, 3- (N-ethyl-N-i-amyl) amino-7-chlorofluorane, 3
-(N-methyl-N-cyclohexyl) amino-6-methyl-7- (3-trifluoromethylphenyl) aminofluorane, 3- (N-methyl-N-i-propyl) amino-6-methyl-7 -Phenylaminofluorane, 3
-(N-benzyl-N-cyclohexyl) amino-5
6-benzo-7- (4-bromonaphthyl) aminofluorane, 3- (N-i-butyl-N-methyl) amino-6
-Methyl-7-phenylaminofluoran, 3- (N-
Ethyl-N-i-amyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-hexyl) amino-7-phenylaminofluorane, 3-
(Nn-amyl-N-methyl) amino-6-methyl-
7-phenylaminofluoran, 3- (N-methyl-N
-Cyclohexyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-methyl-Nn-propyl) amino-6-methyl-7-phenylaminofluorane, 3- (Nn-propyl) -N-i-propyl) amino-6-methyl-7-phenylaminofluorane, 3-
(N-ethyl-N-Sec-butyl) amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-Nn-amyl) amino-6-methyl-7-phenylmethylfluorane, 3-di-n-octylamino-7-
(4-Chlorophenyl) aminofluorane, 3-n-octylamino-7- (4-chlorophenyl) aminofluorane, 3- (Nn-butyl-Nn-amyl) amino-7- (4-acetyl -Phenyl) aminofluorane, 3-n-octylamino-7- (4-chlorophenyl) aminofluorane, 3-n-cetylamino-7-
(4-chlorophenyl) aminofluorane, 3-pyrrolidino-6-methyl-7-phenylaminofluorane, 3
-Pyrrolidino-7- {bis (4-chlorophenyl) methyl} aminofluorane, 3-morpholino-7- {N-propyl-N- (4-trifluoromethylphenyl)} aminofluorane, 3-pyrrolidino-6- Chloro-7-phenylaminofluorane, 3-pyrrolidino-6-methyl-7- (3-trifluoromethylphenyl) aminofluorane, 3-morpholino-7- {N-propyl-N-
(3-trifluorophenyl)} aminofluorane, 3
-(N-ethyl-N-ethoxyethyl) amino-7,8
-Benzofluorane, 3- {N-ethyl-N- (2-ethoxypropyl)} amino-6-methyl-7-phenylaminofluorane, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6 -Methyl-7-phenylaminofluorane, 3- (N-methyl-N-phenyl) amino-7-aminofluorane, 3- (N-methyl-N-phenyl) amino-7-N-methylaminofluorane Three
-(N-methyl-N-phenyl) amino-7-dimethylaminofluorane, 3- (N-methyl-N-phenyl)
Amino-7-dipropylaminofluorane, 3- (N-
Ethyl-N-phenyl) -6-methyl-7- {N-ethyl-N- (4-methylphenyl)} aminofluorane,
3- (N-ethyl-N-phenyl) amino-7-dimethylaminofluorane, 3- (N-ethyl-N-phenyl) amino-7-dipropylaminofluorane, 3-
(N-Ethyl-N-phenyl) amino-7-aminofluorane, 3- (N-phenyl-N-propyl) amino-
7-aminofluorane, 3- (N-ethyl-N-phenyl) amino-7-N-methylaminofluorane, 3-
(N-propyl-N-phenyl) amino-7-N-methylaminofluorane, 3- {N-methyl-N- (4-methylphenyl)} amino-5-methoxy-7-dibenzylaminofluorane, 3- {N-methyl-N- (4-methylphenyl)} amino-6-t-butyl-7- (4-
Methylphenyl) aminofluorane, 3- {N-methyl-N- (4-methylphenyl)} amino-7- (2-methoxybenzoyl) aminofluorane, 3- {N-methyl-N- (4-methyl) Phenyl)} amino-7-acetylaminofluorane, 3- {N-methyl-N- (4-methylphenyl)} amino-7-dibenzylaminofluorane, 3- {N-methyl-N- (4- Methylphenyl)} amino-7-diethylaminofluorane, 3-
{N-methyl-N- (4-methylphenyl)} amino-
7-ethylaminofluorane, 3- {N-methyl-N-
(4-Methylphenyl)} amino-7-aminofluorane, 3- (N-methyl-N-phenyl) amino-6-methyl-7-phenylaminofluorane, 3- (3-trifluoromethylphenyl) amino -6-Diethylaminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-6-methyl-7-phenylaminofluorane, 3- {N-ethyl-N- (4-methylphenyl) )} Amino-7- (N-methyl-N-phenyl) aminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7- (α-phenylethyl) aminofluorane, 3 -{N-ethyl-N- (4-methylphenyl)} amino-7-aminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7-butylaminofluorane 3- {N-ethyl-N- (4-methylphenyl)} amino-7-dibenzylaminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7- {bis- (4 -Methylbenzyl)}
Aminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7-benzoylaminofluorane, 3- {N-ethyl-N- (4-methylphenyl)}
Amino-5-methyl-7-dibenzylaminofluorane, 3- {N-ethyl-N- (4-methylphenyl)}
Amino-5-chloro-7-dibenzylaminofluorane, 3- {N-ethyl-N- (4-methylphenyl)}
Amino-6-methylfluorane, 3- {N-ethyl-N
-(4-Methylphenyl)} amino-5-methoxyfluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7,8-benzofluorane, 3- {N-
Propyl-N- (4-methylphenyl)} amino-6-
Methyl-7- {N-emer-N- (4-methylphenyl)} aminofluorane, 3- {N-propyl-N-
(4-Methylphenyl)} amino-7-aminofluorane, 3- {N-ethyl-N- (4-ethylphenyl)}
Amino-7-aminofluorane, 3- {N-methyl-N
-(4-Ethylphenyl)} amino-7-aminofluorane, 3- {N-ethyl-N- (4-methylphenyl)} amino-7-diethylaminofluorane, 3-
{N-ethyl-N- (4-ethylphenyl)} amino-
7-aminofluorane, 3- {N-propyl-N- (4
-Ethylphenyl)} amino-7-aminofluorane,
3- {N-methyl-N- (2,4-dimethylphenyl)} amino-7-benzylaminofluorane, 3-
{N-ethyl-N- (2,4-dimethylphenyl)}-
7-aminofluorane, 3- {N-methyl-N- (2,
4-dimethylphenyl)} amino-7-methylaminofluorane, 3- {N-ethyl-N- (2,4-dimethylphenyl)} amino-7-ethylaminofluorane, 3
-{N-ethyl-N- (2,4-dimethylphenyl)}
Amino-7-benzylaminofluorane, 3- {N-propyl-N- (2,4-dimethylphenyl)} amino-
7-aminofluorane, 3- {N-methyl-N- (4-
Chlorophenyl)} amino-aminofluorane, 3-
{N-ethyl-N- (4-chlorophenyl)} amino-
7-aminofluorane, 3- {N-propyl-N- (4
-Chlorophenyl)} amino-7-aminofluorane,
3-cyclohexylamino-7-bromoaminofluorane, 2,7-dichloro-3-n-butylamino-6-methylfluorane, 3-di-n-butylamino-6,7-
Butylenefluorane, 3-amino-5-methylfluorane, 2-methyl-3-amino-6-methyl-7-methylfluorane, 1,3,3-trimethylindolino-6 '
-Nitrobenzopyrrillospirane, 1,3,3-trimethylindolino-6'-nitro-8'-methoxybenzopyrrolospiran, 1,3,3-trimethylindolino-
6'-Bromobenzopyrrolispirane, 1,3,3-trimethylindolino-8'-methoxybenzopyrrilospirane, 1,3,3-trimethylindolino-benzopyrrilospirane, 1,3,3-trimethyl Indolino β-naphthopyrilospirane, tris (4-dimethylaminophenyl) methane-2-carboxylate (CVL), bis (4-dimethylaminophenyl) phenylmethane-2-
Carboxylate (MGL), Bis (4-dimethylaminophenyl)-(4-chloro) phenylmethane-2-carboxylate, Bis (4-dimethylaminophenyl)
-(4-Diethylamino) phenylmethane-2-carboxylate, bis (4-dibutylaminophenyl) phenylmethane-2-carboxylate, {2-hydroxy- (4-diethylamino) phenyl}-(2-methoxy-5- Methylphenyl) phenylmethane-2-carboxylate, {2-hydroxy- (4-dimethoxyamino) phenyl}-(2-hydroxy-5-chlorophenyl) phenylmethane-2-carboxylate, (4-dimethylaminophenyl)- (2-Hydroxy-4-chloro-5-methoxyphenyl) phenylmethane-2-carboxylate, 3- {2-ethoxy- (4-diethylamino) phenyl} -3- (2-methyl-1-ethylindole-3 -Yl) -4-azaphthalide, 3- {2-ethoxy- (4-die Arylamino) phenyl} -3- (2
-Methyl-1-n-octylindol-3-yl)-
4-azaphthalide, 3,3-bis (2-methyl-1-ethylindol-3-yl) phthalide, 3- {2-methoxy- (4-diethylamino) phenyl} -3- (2-
Methyl-1-ethylindol-3-yl) -phthalide, 3- {2-methyl- (4-diethylamino) phenyl} -3- (1,2-dimethylindol-3-yl)
-Phthalide, 3,3-bis (2-methyl-1-octylindol-3-yl) phthalide, rhodamine anilinolactam, rhodamine-2-chloroanilinolactam,
Rhodamine-4-chloroanilinolactam, bis {2-
Methyl- (4-dimethylamino) phenyl}-{(2,
5-dimethylamino) phenyl} methane.

A preferred example of the electron-accepting phenol compound used in the present invention has a melting point of 70 ° C. or higher. When an electron-accepting phenol compound having a melting point of 70 ° C. or less and a color development / erasing control polymer having a glass transition temperature of about 60 ° C. are used, melting of the electron-accepting phenol compound begins to occur when heated to the decolorization temperature range. As a result, there is a tendency that decolorization is less likely to occur. Therefore, it is preferable to use an electron-accepting phenol compound having a temperature of 70 ° C. or higher. As a specific example of the electron-accepting phenol compound, an ester of gallic acid is preferable, and more specifically, n-propyl gallate, n-butyl gallate, i-amyl gallate, lauryl gallate, cetyl gallate. , Myristyl gallate, stearyl gallate, behenyl gallate and the like. However, it is not limited to these.
The color development / erasing control polymer used in the present invention is always compatible with the electron-donating color developable compound from the viewpoint of color development / decoloration control, and is compatible or incompatible with the electron-accepting phenol compound. Must be a polymer capable of causing Further, the glass transition temperature of the polymer is involved in color development and decoloring in relation to the electron-accepting phenol compound.
When the glass transition temperature of the color development / decoloration control polymer is high, decolorization is unlikely to occur, and when it is low, the decolorization is easily controlled. From this result, the glass transition temperature of the color development / erasing control polymer is preferably 60 ° C. or lower. That is, when the glass transition temperature is higher than 60 ° C., it becomes difficult to maintain the incompatibility with the electron-accepting phenol compound at the time of decoloring. That is, since the polymer for controlling color development and erasing is in a hard state, phase separation is less likely to occur, which makes it difficult to perform color erasing, or it takes time for color erasing. Regarding color formation, it is relatively unaffected by the glass transition temperature of the color development / erasing control polymer, but when the glass transition temperature exceeds 60 ° C., the color development response and contrast tend to deteriorate. From this, it is preferable to use a polymer having a glass transition temperature of 60 ° C. or lower.

Further, the color development / decoloration control polymer used in the present invention is clearly compatible with or incompatible with the electron-accepting phenol compound under specific conditions, that is, from the viewpoint of excellent color development / decoloration control, it is a styrene polymer. And diene polymers are preferred. From the above, when the color development / erasing control polymer used in the present invention is exemplified, a styrene polymer and a diene polymer are preferable, and specifically, polystyrene, styrene-butadiene copolymer, styrene-isoprene-styrene copolymer, styrene-epoxy modified styrene. Copolymer,
Styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, styrene-ethylene-propylene-styrene copolymer, styrene-ethylene-
Examples include, but are not limited to, butadiene-styrene copolymers, butadiene polymers, isoprene polymers, and the like.

In the present invention, the compounding ratio of the color development / erasing control polymer: electron accepting phenol compound: electron donating color developing compound is 1: 0.1 to 0.6: 0.01 to 0.
09 is preferable. When the ratio of the electron-accepting phenol compound exceeds this range, it becomes difficult to control the compatibility and incompatibility required for color development / erasing, and the color development state cannot be maintained even when the recording material in the heat color development state is cooled. There is a tendency. That is, the three components of the color development / erasing control polymer, the electron-accepting phenol compound and the electron-donating color developing compound are not completely compatible with each other, and most of them are non-compatible due to the incompatible electron-accepting phenol compound. They are compatible with each other, and as a result, the color density upon cooling decreases, which is not preferable. On the other hand, if the ratio is less than this range, a sufficient color density for practical use cannot be obtained, resulting in poor contrast and unsuitable for use as a recording material, which is not preferable. Further, if the ratio of the electron-donating color-forming compound exceeds this range, some electron-donating color-forming compounds may not always be in a compatible state, and as a result, the electron-accepting property may be lost. Even if the phenol compound and the color development controlling polymer undergo compatible or incompatible changes, they can always react with the electron-donating color-forming compound, so that decolorization is less likely to occur. This is not preferable because the base density becomes high, resulting in poor contrast. On the other hand, if it is less than this range, sufficient color density cannot be obtained as in the case where the ratio of the electron-accepting phenol compound decreases, which is not preferable. The compounding ratio of the electron-accepting phenol compound to the electron-donating color developing compound is particularly preferably in the range of 1: 0.1 to 0.9 by weight. When the proportion of the electron-accepting phenol compound is high, the color density at cooling tends to be low, and when the proportion of the electron-accepting phenol compound is low, the color density is not obtained or the contrast is deteriorated. It is not preferable because it is present. Based on the results of examining these compounding ratios, the respective relationships are as follows. That is, the compounding ratio of the color development / erasing control polymer and the electron-accepting phenol compound influences the color density and the color erasing speed. The blending ratio of the color development / erasing control polymer and the electron-donating color developing compound affects the color density and the base density. It was revealed that the compounding ratio of the electron-accepting phenol compound and the electron-donating color-forming compound affects the color density and the contrast. Therefore, as described above, a practical recording material cannot be obtained without limitation of the compounding ratio,
Limiting the compounding ratio is necessary for producing a desired recording material. The mechanism of coloring and erasing in the present invention is
Since it occurs due to the compatibility and incompatibility of the color development / erasing control polymer and the electron-accepting phenol compound, it is important to limit the compounding ratio of the color development / decoloration controlling polymer and the electron-accepting phenol compound.

The reversible thermochromic recording medium of the present invention comprises the above recording materials arranged in layers on a support, and the support may be a transparent, translucent or opaque polymer film or sheet, synthetic paper and processed paper. , A glass plate, a metal plate, or the like is used, and a recording layer is provided directly on the support, or an undercoat layer is once provided on the support to improve the adhesion between the support and the recording layer, and then the recording layer is formed thereon. May be provided.
Such an undercoat layer has an effect of imparting heat insulating property and the like in addition to improving the adhesiveness. Further, prevention of fusion between the surface of the recording medium and the thermal head, improvement of scratch resistance of the recording layer,
A transparent protective layer may be provided on the surface of the recording medium in order to prevent the recording layer from being oxidized and to prevent the recording layer from being contaminated by harmful gas or the like. The protective layer can be formed by vapor deposition of an inorganic material, coating with a polymer solution, or by stacking polymer films. In order to laminate the polymer film, an adhesive layer or an adhesive layer may be provided between the polymer film and the recording layer.

The reversible thermochromic recording medium using the reversible thermochromic recording material of the present invention contains a coloring agent in the recording layer or in a layer other than the recording layer, such as a support, an undercoat layer, a protective layer, an adhesive layer or an adhesive layer. The color of the coloring agent, which is present in the adhesive layer,
It is possible to change the color of the colorant and the color in which the electron-donating color-forming compound in the colored state is mixed from colored to colored.
When used in the recording layer, the type and amount of the coloring agent that can be used here do not hinder the color-forming reaction between the electron-accepting phenol compound and the electron-donating color-forming compound, and eliminate the color-erasing effect. It is necessary that the color control polymer and the electron-accepting phenol compound do not inhibit the change in compatibility and incompatibility, and any compound satisfying such requirements can be used. Also, when including when it exists in other than the recording layer,
Addition that causes a remarkable decrease in contrast is not preferable. Similarly, an additive such as an ultraviolet absorber may be added to protect the recording material. The reversible thermochromic recording material of the present invention can be used as a reversible thermochromic recording medium by forming predetermined characters, figures or patterns on a support. That is, when the recording layer is heated to a coloring temperature range, part or all of the recording layer develops or changes color,
It can be recorded or displayed. At this time, in the recording layer, in addition to the development of a single color, a reversible thermochromic recording material that develops a different color is formed by coating it in various patterns such as a stripe shape and a matrix shape, thereby forming a plurality of colors. It will be possible.
Furthermore, the reversible thermochromic recording material of the present invention has the ability to hide the underlayer in the color-developed state. Therefore, a predetermined character, figure or pattern is previously formed on the support,
It is also possible to use the recording layer laminated thereon. By heating the recording layer to a coloring temperature range or an erasing temperature range, a part or all of the recording layer is colored, erased or discolored, and a part of characters, figures or patterns on the support. Alternatively, all of them can be hidden or seen through to be reversibly recorded or displayed. Further, predetermined characters, figures, and patterns may be formed on both the recording layer and the support and used in combination. Further, the recording material in the present invention is a term including a display material.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described together with its operation, as to how the present invention is implemented. The reversible thermochromic recording material of the present invention comprises a color development / erasing control polymer: an electron-accepting phenol compound: an electron-donating color developing compound in a weight ratio of 1: 0.1 to 0.6: 0.01 to 0. It can be manufactured by dissolving it in a volatile organic solvent at a ratio of 09 to form a mixed solution. It is also possible to disperse an electron-accepting phenol compound and an electron-donating color-forming compound in a color development / erasing control polymer emulsion formed by emulsion polymerization. A reversible thermochromic recording medium can be manufactured by coating this support on a support and drying it.

In the reversible thermochromic recording material of the present invention, the time for maintaining the color-developed state can be controlled arbitrarily. That is, it is possible to maintain the color-developed state for a long period of one month or more, or to erase the color in tens of minutes. It is possible to control the maintenance time of the color-developed state by selecting the combination of the electron-accepting phenol compound and the color-developing / decoloring controlling polymer and the compounding ratio thereof. For example, gallic acid ester (n-
Propyl, n-butyl, i-amyl, stearyl, cetyl, lauryl, etc.) and a styrene-butadiene copolymer or a styrene- (meth) acrylic ester copolymer are used in combination, the colored reversible thermochromic recording material is at room temperature. It is possible to maintain the color-developed state for 1 month or longer. When a gallic acid ester and a styrene-isoprene-styrene copolymer are used in combination, the color-developed reversible thermochromic recording material can be erased by leaving it at room temperature for several tens of minutes.

Since the reversible thermochromic recording material of the present invention can be used as a recording medium arranged in layers on a support, the organic solvent used when forming a mixed solution as a solution is used for color development and decolorization reaction. A solvent that does not participate is suitable, and if a solvent that participates in the reaction is used, it must be one that is volatilized and removed from the system during the color development reaction. The recording material layer provided on the support is preferably a dry film having a thickness of 1 μm to 30 μm, more preferably 2 μm to 6 μm. The recording medium of the present invention can be recorded by displaying a color with a thermal transfer printer or the like, and can be erased by blowing hot air having a decoloring temperature.

Next, an embodiment will be described in terms of the operation of the present invention. The reversible thermochromic recording material of the present invention exhibits hysteresis and does not disappear even when the composition in the decolored state is heated at room temperature to develop color and cooled to room temperature. FIG. 1 shows the phenomena of coloring and decoloring of the thermal recording material of the present invention obtained by evaporating and removing an organic solvent from an organic solvent solution of an electron-donating color-forming compound, an electron-accepting phenol compound and a coloring / decoloring control polymer. Shown in. In FIG. 1, the decolored state A is heated, and after passing through B and C, D (a temperature near D or higher is called a coloring temperature range)
When the temperature reaches, the electron-donating color developable compound, the electron-accepting phenol compound and the color development / decoloration control polymer in the thermal recording material become compatible with each other to develop color, and when cooled to room temperature The route from D to E, which is a route different from the route to the coloring state D, is followed, and the coloring state is maintained. Then E
When the heat recording material in the state is heated to a temperature between B and C (the temperature range in the vicinity is called the decoloring temperature range) to change from the E state to the B and C states, the electron-accepting phenol compound is a coloring and decoloring control polymer. Becomes a non-compatible state, and the bond with the electron-donating color-developing compound, which had reacted and developed a color, is broken and the thermal recording material becomes a decolored state. When this is cooled to room temperature, it does not return to the E state but becomes the A state and the decolored state is maintained, and it is stable over time. A major feature is that the reaction exhibits a reversible hysteresis through different paths. This phenomenon is produced by evaporating and removing the solvent from a homogeneous solution of crystal violet lactone (hereinafter CVL) as an electron-donating color-forming compound, stearyl gallate as an electron-accepting phenolic compound, and styrene-butadiene copolymer as a color development control polymer. The reversible thermochromic recording material of the present invention [X], the material [Y] obtained by evaporating the solvent from the homogeneous solution of CVL and styrene-butadiene copolymer, and the solvent of the homogeneous solution of stearyl gallate and styrene-butadiene copolymer. Differential scanning calorimetry (hereinafter DSC) for each of the materials [Z] produced by evaporation
Will be explained in more detail based on the thermally analyzed data. DSC measurement is made by Seiko Electronics Co., Ltd. D
SC-SSC580 type was used and the heating rate was 5 ° C./min.

The line a in FIG. 2 shows the thermal recording material [X] heated to 120 ° C. which is the coloring temperature range and then cooled to room temperature. The results are obtained by heating the recording material [X] to 60 ° C., which is the decoloring temperature range, and then cooling it to room temperature, and performing DSC measurement using samples in the decoloring state. Endothermic peak 2-
1 and endothermic peak 2-11 are associated with the change of the polymer to the amorphous state, and endothermic peaks 2-2, 2-3 and 2-
No. 4 is associated with the thermal recording material in which the color-developed states having slightly different energies are mixed, and the endothermic peak 2-1
Nos. 2 and 2-14 are also associated with the thermal recording material in which the same states of color-developed states having slightly different energies are mixed. Endothermic peak 2-15 is associated with the melting of stearyl gallate, which is not yet involved in the reaction with CVL during the temperature rising process. That is, the endothermic peak 2- of the line b in FIG.
No. 15 shows that in the decolored state, stearyl gallate is incompatible and exists independently. On the other hand, in FIG. 2 line a, there is no endothermic peak corresponding to 2-15. If stearyl gallate in an incompatible state is present in the sample, an endothermic peak corresponding to 2-15 is likely to occur near 100 ° C. near the melting point, but there is no endothermic peak at that point. The color-developed sample [X] used for the measurement shows that the three components of CVL, stearyl gallate and styrene-butadiene copolymer are in a compatible state.

FIG. 3 shows the results of DSC measurement of a sample in which the material [Y] was heated to 60 ° C. in the decoloring temperature range and then cooled to room temperature. 120
The results of the DSC measurement of heating to ℃ and cooling to room temperature are shown. Endothermic peak 3 seen in Figures 3 and 4
-1 and 4-1 are endotherms when the polymer is in an amorphous state, and there is almost no difference between the two. This suggests that the donor color-forming compound is homogeneously dissolved.

FIG. 5 shows the results of DSC measurement using a sample obtained by heating the material [Z] to 70 ° C. in the decoloring temperature range and then cooling it to room temperature. The endothermic peak 5-1 is due to the discoloration-controlling polymer being in an amorphous state, which is a broader endothermic peak as compared with FIGS. What is happening is due to the effect of the electron-accepting phenolic compound, that is, it exists in an incompatible state. Further, the endothermic peak 5-2 is associated with the dissolution of the electron-accepting phenol compound existing in an incompatible state. The temperature at which the endothermic peak appears is affected by coexisting substances,
There may be some deviation.

Summarizing the results of the above DSC measurements, the mixture of the color development / erasing control polymer and the electron-donating color developing compound is always in a compatible state from room temperature to the color erasing temperature range to the color development temperature range. . Therefore, also in the present invention, it is necessary to select an electron-donating color-developing compound that is always compatible with the color development / erasing control polymer, and it is necessary to make a preferable combination. Further, the electron-accepting phenol compound is dissolved in the color development temperature range and is compatible with the color development / erasing control polymer, so that it reacts with the color-forming compound which is always in a compatible state to form a color. When this is cooled to room temperature, the compatible state is maintained and the colored state can be maintained. The electron-accepting phenol compound involved in the reaction becomes incompatible with the color-developing control polymer when heated from room temperature to the color-erasing temperature range, and the bond with the color-developing compound is broken to erase the color. To do. Since the incompatible state is maintained even when this is returned to room temperature, stable decolorization can be maintained.

Next, in the decolored state, X-ray diffraction measurement was performed to clarify the crystalline state of the electron-accepting phenol compound and the color development / decoloration controlling polymer. FIG. 6 shows the X-ray diffraction measurement result of the reversible thermochromic recording material [X] in the decolored state. The X-ray diffraction measurement result of the styrene-butadiene copolymer is shown in FIG. 7, and the X-ray diffraction measurement result of stearyl gallate is shown in FIG. In FIG. 8, stearyl gallate is 2θ / deg. 2 to 25, some crystallization peaks are recognized, and in particular 2θ / deg. There is a large crystallization peak between 2 and 7. In FIG. 7, the styrene-butadiene copolymer is 2θ / deg. A relatively small crystallization peak 7-2 is recognized around 23. On the other hand, in FIG. 6, the reversible thermochromic recording material [X] in the decolored state is
Although there are small peaks shown as 6-1 and 6-2, 6-
2 is based on crystallization of a styrene-butadiene copolymer. 6-1 is a product based on stearyl gallate, and it can be presumed that stearyl gallate is hardly crystallized. As described above, the present invention relates to the relationship between the color-developing control polymer, the electron-accepting phenol compound, and the electron-donating color-forming compound, and particularly, the compatibility between the color-developing control polymer and the electron-accepting phenol compound. The reversible change in compatibility causes reversible color development and decolorization. The state of incompatibility with the polymer of the electron-accepting phenol compound may be a crystalline state or an amorphous state of the phenol compound,
It is not bound to separate from the polymer in a particular state. That is, no exothermic peak due to crystallization of the phenol compound is observed in FIG. Also,
From the X-ray diffraction measurement results of FIG. 6, no clear crystallization peak of the phenol compound was observed, which is clearly different from the discoloration due to the aggregation crystallization of the long-chain alkyl group of the phenol compound. .

[0025]

Embodiments will be described below with reference to embodiments.

Example 1 20 parts by weight of styrene-butadiene copolymer (trade name "Asmer", manufactured by Asahi Kasei Corporation, Tg = -60 ° C) Stearyl gallate 10 parts by weight Crystal violet lactone (CVL) 1 part by weight The above composition The product was dissolved in 170 parts by weight of tetrahydrofuran (hereinafter THF) to prepare a solution of a reversible thermochromic recording material. This solution was applied to a polypropylene synthetic paper having a thickness of 110 μm (trade name “YUPO FBD # 110”, manufactured by Oji Yuka Co., Ltd.) using a wire bar, and then 100
By heating to dryness at ℃, a blue-violet color develops to a thickness of 4
A recording layer made of a reversible thermochromic recording material having a thickness of μm was provided to prepare a recording medium. When this recording medium was heated to 60 ° C. and cooled to room temperature (20 ° C.), the blue-violet color disappeared and the color became white, which was close to the color-developed state of the base synthetic paper. The medium is heated to 120 ° C., cooled to room temperature, then
When the operation of heating to 60 ° C. and then cooling to room temperature was repeated, color development and color erasing could be performed reversibly. At this time, the optical density of the color-developed state and the color-erased state was measured by Macbeth densitometer RD
When measured using -915, it was 1.5 in the colored state.
2, an OD value of 0.14 was shown in the decolored state, and an excellent recording medium was obtained. Hereinafter, the same machine was used for OD value measurement.

Example 2 Styrene-butadiene copolymer 20 parts by weight Stearyl gallate 10 parts by weight CVL 1 part by weight The above composition was dissolved in 170 parts by weight of a mixed solvent of methyl ethyl ketone (abbreviated as MEK) and toluene 1: 1 and reversible. A solution of thermochromic recording material was prepared. 110 μm of this solution
Was applied to a polypropylene synthetic paper having a thickness of 1. By heating and drying this at 120 ° C., a recording layer made of a reversible thermochromic recording material having a thickness of 4 μm, which developed a blue-violet color, was provided. A 5% aqueous solution of methyl cellulose (trade name "Metroze SM-25", manufactured by Shin-Etsu Chemical Co., Ltd.) was applied onto the recording layer using a wire bar, and then dried by heating to form an intermediate layer having a thickness of 2 µm. . After applying a UV curable epoxy resin (trade name "Adeka Optomer KR510", manufactured by Asahi Denka Co., Ltd.) on this intermediate layer using a wire bar, 400 W
A cured film having a thickness of 2 μm was formed using a mercury lamp to prepare a recording medium with a protective layer. An image is formed on this recording medium using a thermal transfer printer (trade name "PC-PR150n", manufactured by NEC Corporation), and then the recording medium is passed between rubber heat rolls set at 65 ° C. The image was erased. When the optical densities in the colored state and the decolored state at that time were measured, the OD values were 1.50 in the colored state and 0.16 in the decolored state. Further, the same coloring and erasing operations as those described above were repeated for 30 cycles, but the thermal head of the printer and the surface of the protective layer of the recording medium were not fused and the OD value did not significantly change. It was

Example 3 Polyethylene terephthalate (PE having a thickness of 100 μm)
A 5% aqueous solution of methyl cellulose was applied to a T sheet) using a wire bar and dried by heating to form an undercoat layer having a thickness of 2 μm. Next, styrene-butadiene copolymer 20 parts by weight stearyl gallate 10 parts by weight CVL 1 part by weight The above composition is mixed solvent 170 of MEK and toluene 1: 1.
It was dissolved in parts by weight to prepare a reversible thermochromic recording material solution (solution A). Next, 20 parts by weight of styrene-butadiene copolymer, 10 parts by weight of stearyl gallate, 1 part by weight of rhodamine B lactam were dissolved in 170 parts by weight of a mixed solvent of MEK and toluene 1: 1 to prepare a solution of the reversible thermochromic recording material (solution B). ) Is made. On the PET sheet provided with the undercoat layer,
Use a gravure plate to form an 8 mm wide stripe A
The solution and the solution B were separately applied and heated and dried to prepare a recording medium having a recording layer capable of developing blue-violet and red colors in a stripe pattern made of a reversible thermochromic recording material having a thickness of 4 μm. A 5% aqueous solution of methylcellulose was applied onto the recording medium using a wire bar and dried to a thickness of 2 μm.
40 is formed on the intermediate layer by applying a UV curable epoxy resin on the intermediate layer using a wire bar.
A 2 μm-thick cured film was formed using a 0 W mercury lamp to prepare a recording medium with a protective layer. It was possible to develop two colors on the recording medium using the thermal transfer printer. Also,
It was possible to erase the color using hot air from a dryer at about 80 ° C.

Examples 4 to 22 The compositions of Formulation Examples 4 to 22 in Table 1 were each dissolved in 170 parts by weight of THF to prepare a solution of a reversible thermochromic recording material,
The composition was applied to polypropylene synthetic paper with a wire bar and then dried by heating to form a recording layer made of a reversible thermochromic recording material on the synthetic paper. Further, a 5% aqueous solution of methyl cellulose was applied onto the recording layer using a wire bar, and then dried by heating to form an intermediate layer having a thickness of 2 μm. Further, a UV curable epoxy resin was applied onto the intermediate layer with a wire bar. And then apply a thickness of 2 using a 400W mercury lamp.
A cured film having a thickness of μm was formed to prepare a recording medium with a protective layer. In any of the examples, an image could be formed using the thermal transfer printer. Also, the image could be erased by passing it through a rubber heat roll set at 75 ° C. Further, this coloring and decoloring could be repeated. Table 2 shows the measured optical density values in the color-developed state and the decolored state of each example.

[0030]

[Table 1]

(Note) CVL: Yamada Chemical Co., Ltd., Crystal Violet Lactone (Blue Purple) NC-BK: Hodogaya Chemical Co., Ltd., Fluoran Leuco Dye (Black) APT: Yamada Chemical Co., Fluoran Leuco Dye (Green) OR-55: Yamada Chemical Co., Ltd., Fluoran-based leuco dye (orange) NBP-1: Yamamoto Kasei Co., Ltd., Azaphthalide-based leuco dye (blue) NCY-2 [1]: Hodogaya Chemical Co., Ltd. , Azomethine-based leuco dyeing department (yellow) TH-107: Hodogaya Chemical Co., Ltd., Fluoran-based leuco dye (black) Styrene-butadiene copolymer: Trade name "Asmer", Asahi Kasei Co., Ltd., Tg = -60 ° C Styrene -Acrylic ester copolymer: trade name "Heimer TB-1000F", manufactured by Sanyo Chemical Industries, Ltd.,
g = 58 ° C. Butadiene polymer: trade name “RB-820”, manufactured by Japan Synthetic Rubber Co., Ltd., Tg = −12 ° C. styrene-isoprene-styrene copolymer; trade name “SIS-5000”, manufactured by Japan Synthetic Rubber Industry Co., Ltd. ,
Tg = -70 ° C Styrene-ethylene-butadiene-styrene copolymer: trade name "Clayton G-1650", Shell Japan Co., Tg = -42 ° C Vinyl chloride-vinyl acetate copolymer: trade name "Denka vinyl 1000A", electrochemical Kogyo Co., Ltd., Tg = 6
5 ° C. Poly (p-vinylphenol): trade name “Marca Linker MB”, manufactured by Maruzen Petrochemical Co., Ltd., Tg = 147 ° C. Polymethylmethacrylate: trade name “Dianal BR”
-77 ", manufactured by Mitsubishi Rayon Co., Ltd., Tg = 80 ° C

[0032]

[Table 2]

Comparative Examples 1 to 10 The compositions of Formulation Examples 23 to 32 in Table 3 were each dissolved in 170 parts by weight of THF, and this solution was applied to polypropylene synthetic paper having a thickness of 110 μm using a wire bar. This was heated and dried at 120 ° C. to form a recording layer having a thickness of 4 μm. A 5% aqueous solution of methyl cellulose was applied to the recording layer using a wire bar and then dried by heating to form an intermediate layer having a thickness of 2 μm. On top of this middle layer,
A UV curable epoxy resin was applied using a wire bar, and then a cured film having a thickness of 2 μm was formed using a 400 W mercury lamp to prepare a recording medium with a protective layer. Using this recording medium, the color density and decolorization density obtained in the same manner as in Example 2 were measured and are shown in Table 4.

Comparative Example 11 Epoxy resin 18.6 parts by weight (trade name "Adeka Resin EP-4000", manufactured by Asahi Denka Co., Ltd.) Triethylene tetramine 1.4 parts by weight Stearyl gallate 10 parts by weight CVL 1 part by weight The above composition The product was dissolved in 180 parts by weight of toluene, and this solution was applied to polypropylene synthetic paper having a thickness of 110 μm using a wire bar. Then, this is heated and dried at 80 ° C. to remove the solvent, and then heat cured at 80 ° C. for 24 hours,
A recording layer having a thickness of 4 μm was provided. Thereafter, a protective layer was prepared by the same method as in Comparative Examples 1-10. Using this recording medium, the color density and decolorization density obtained in the same manner as in Example 2 were measured and are shown in Table 4.

Comparative Example 12 Polyol 6.4 parts by weight (Brand name "Takelac U-25" 75% butyl acetate solution, manufactured by Takeda Chemical Industries, Ltd.) Polyisocyanate 13.6 parts by weight (Brand name "Takenate D-110N") 75% ethyl acetate solution, manufactured by Takeda Pharmaceutical Co., Ltd.) Stearyl gallate 10 parts by weight CVL 1 part by weight The above composition is dissolved in MEK145 parts by weight, and this solution is coated with a wire bar on polypropylene synthetic paper having a thickness of 110 μm. Applied. Then, this was heated and dried at 80 ° C. to remove the solvent, and then heat-cured at 80 ° C. for 24 hours to form a recording layer having a thickness of 4 μm. Thereafter, a recording medium with a protective layer was produced by the same method as in Comparative Examples 1-10. Using this recording medium, the color density and decolorization density obtained in the same manner as in Example 2 were measured and are shown in Table 4. Comparative Example 1
The recording materials obtained in Nos. 1 and 12 were printed using a thermal transfer printer, but no color was developed.

[0036]

[Table 3]

(Note) The abbreviations in the table are the same as in Table 1.

[0038]

[Table 4]

From the results of the comparison between Example 11 and Comparative Examples 1, 4 and 6, it is found that the critical point of the compounding ratio of the color development / erasing control polymer and the electron-accepting phenol compound is appropriate. In addition, Examples 1, 4 and 9 and Comparative Example 2,
From the results of comparison of 3, 5 and 8, it is found that the critical point of the compounding ratio of the color development / erasing control polymer and the electron donative color developing compound is appropriate. In Example 22, since the glass transition temperature of the color development / erasing control polymer exceeds 60 ° C., incompatibility change for decoloring the polymer and the electron-accepting phenol compound is less likely to occur, and thus the color-erasing-time It slightly affects the concentration. The recording media obtained in Comparative Examples 7 and 10 showed almost no color. The recording media obtained in Comparative Examples 8 and 9 had a sufficient color density, but the density at the time of decolorization was large and was not suitable for practical use. The reason why unsatisfactory results were obtained except for the compounding ratio was that in Comparative Example 7, the long-chain saturated carboxylic acid was incompatible with the electron-donating color-forming compound and could not react. 1
This is because in 1 and 12, the functional group of the polymer that was supposed to be the color development / erasing control polymer causes color development inhibition. This is because in Comparative Example 9, the functional group in the color development / erasing control polymer and the electron donative color developing compound are always in a state of being capable of reacting.

[0040]

The present invention has the advantages that the material can be used without deterioration even if the coloring and erasing are repeated, the image contrast is good, and desired recording can be retained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the relationship between temperature and color density of a reversible thermochromic recording material.

FIG. 2 is a DSC chart of reversible thermochromic recording materials in a colored state and a decolored state.

FIG. 3: CVL heated to 60 ° C. and then cooled to room temperature
And DSC of homogeneous material of styrene-butadiene copolymer
It is a chart.

FIG. 4 CV heated to 120 ° C. and then cooled to room temperature
DS of homogeneous material of L and styrene-butadiene copolymer
It is a C chart.

FIG. 5 is a DSC chart of a homogeneous material of stearyl gallate and styrene-butadiene copolymer that has been heated to 70 ° C. and then cooled to room temperature.

FIG. 6 is an X-ray diffraction chart in the decolored state of the reversible thermochromic recording material.

FIG. 7 is an X-ray diffraction chart of stearyl gallate.

FIG. 8 is an X-ray diffraction chart of a styrene-butadiene copolymer.

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Claims (14)

[Claims] 1. A reversible thermochromic recording material capable of repeating coloring and erasing by heating to a coloring and erasing temperature, comprising at least a. An electron-accepting phenolic compound and b. An electron-donating color-forming compound and c. It has a temperature range that is always compatible with the electron-donating color-forming compound, is compatible with the electron-accepting phenolic compound, and is not compatible with it, and has a glass transition temperature below the melting point of the electron-accepting phenolic compound. A color development / decoloration control polymer, wherein the compounding ratio of the color development / decoloration control polymer: electron-accepting phenol compound: electron-donating color developing compound is 1: 0.1 to 0.6: weight ratio.
A reversible thermochromic recording material having a color erasing temperature range of 0.01 to 0.09 and a decoloring temperature range lower than a color development temperature range. 2. The reversible thermochromic recording material according to claim 1, wherein the color development / erasing control polymer has a glass transition temperature of 60 ° C. or lower. 3. The reversible thermochromic recording material according to claim 1, wherein the color development / erasing control polymer is one or more polymers selected from styrene polymers and diene polymers. 4. The styrene-based polymer is polystyrene, styrene-butadiene copolymer, styrene-isoprene-styrene copolymer, styrene-epoxy modified styrene copolymer, styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, styrene-ethylene-butadiene-styrene. Copolymer, styrene-ethylene-propylene-styrene copolymer, styrene-
1 to 2 or more selected from polymethyl methacrylate graft polymer, epoxy-modified polystyrene-polymethyl methacrylate graft polymer, acid-modified acrylic-polystyrene graft polymer, epoxy-modified polystyrene-polystyrene graft polymer, polybutylene terephthalate-polystyrene graft polymer The reversible thermochromic recording material according to claim 3, which is a polymer of 5. The reversible thermochromic recording material according to claim 3, wherein the diene polymer is one or more polymers selected from butadiene polymers and isoprene polymers. 6. The reversible thermochromic recording material according to claim 1, wherein the electron-accepting phenol compound is a gallic acid ester. 7. The electron-accepting phenol compound has the general formula: The reversible thermochromic recording material according to any one of claims 1 to 6, which is a gallic acid ester represented by the formula (wherein R is an alkyl group of C ₃ or more). 8. A reversible thermochromic recording medium comprising a reversible thermochromic recording layer comprising the reversible thermochromic recording material according to any one of claims 1 to 7 on a support. 9. An undercoat layer for improving adhesion is provided between the reversible thermochromic recording layer and the support.
The reversible thermochromic recording medium according to claim 8. 10. The reversible thermochromic recording medium according to claim 8, wherein a protective layer is provided on the reversible thermochromic recording layer. 11. The reversible thermochromic recording medium according to claim 10, wherein the protective layer is made of a transparent polymer. 12. The reversible thermochromic recording medium according to claim 8, wherein a colorant is contained in the reversible thermochromic recording medium. 13. A single-color or multi-color reversible thermochromic recording layer comprising a reversible thermochromic recording material is formed on a support in a predetermined character, figure or pattern.
The reversible thermochromic recording medium according to any one of claims 8 to 12. 14. A reversible thermochromic recording layer of a single color or a plurality of colors composed of a reversible thermochromic recording material is formed by laminating on a whole or a part of a support on which predetermined characters, figures or patterns are formed in advance. The reversible thermochromic recording medium according to any one of claims 8 to 12, wherein