JP3441032B2 - Reversible thermosensitive coloring composition and reversible recording medium using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to an electron-donating colorant
Utilizing the color reaction between the compound and the electron-accepting compound
The present invention relates to a reversible thermosensitive coloring composition. The present invention also provides
Control thermal energy by using reversible thermosensitive coloring composition
Reversible thermal recording that can form and erase colored images
Regarding recording media. [0002] 2. Description of the Related Art Conventionally, an electron-donating color-forming compound (hereinafter referred to as an electron-donating color-forming compound) has been proposed.
A color former or a leuco dye) and an electron-accepting compound.
(Hereinafter, also referred to as a color developer)
Thermal recording media are widely known, such as facsimile,
Used for printers such as microprocessors and chemical measuring instruments.
Have been. However, these conventional commercialized
All recording media have irreversible color and have been recorded once
Images cannot be deleted and used repeatedly. [0003] On the other hand, those which reversibly perform color development and decoloration
Are also proposed in patent gazettes and the like, for example,
Gallic acid and phloroglucinol combined
Using the thing (Japanese Patent Laid-Open No. 60-193691)
Report), phenolphthalene and thymolphthale as color developers
Using compounds such as in (JP-A-61-23768)
No. 4), a color former, a developer and a carboxylic acid ester
A recording layer containing a homogeneous solution (Japanese Patent Laid-Open No. 62-13 / 1987)
No. 8556, Japanese Patent Application Laid-Open No. 62-138568 and
JP-A-62-140881) and Asco as a developer
Using a rubic acid derivative (JP-A-63-17368)
No. 4), bis (hydroxyphenyl) vinegar as a developer
Using salts of acid or gallic acid with higher fatty acid amines
(JP-A-2-188293 and JP-A-2-188)
No. 294) is disclosed. However,
The conventional reversible thermosensitive recording medium shown above has stable color development.
And the decolorization, or the color density and repetition
Problems remain in terms of stability in
It is not a satisfactory recording medium. [0004] We first developed long-chain aliphatic groups as color developers.
Organic phosphoric acid, carboxyl compounds, and phenol compounds
Product, hydroxyphosphonic acid, etc.
By combining with leuco dye as a coloring agent,
The coloring and decoloring can be easily performed by heating and cooling conditions.
And its coloring and decoloring states at room temperature
And maintain stable color, and at the same time,
Reversible thermochromic compositions that can be defined and repeated, and
And a reversible thermosensitive recording medium using this as the recording layer
(JP-A-5-124360). This is stable color development
Practical level of performance in terms of balance between color and decolorability and color density
Although it has a function, it can be used in a wider range of usage environments.
There is room for improvement in the application range of
Was. Then, phenol with long-chain aliphatic hydrocarbon group
Although the use of specific structures for compounds has been proposed
(Japanese Patent Application Laid-Open No. 6-210954).
had. [0005] SUMMARY OF THE INVENTION The object of the present invention is to
Stable color development and color erasure, improving problems in the prior art
And maintain a wide range of operating and environmental conditions
Provide a reversible color-forming composition and a reversible thermosensitive recording medium
It is in. [0006] Means for Solving the Problems The present inventors have proposed such a method.
Reversible color-decoloration phenomenon of the composition of
In addition, a color developer of a developer having a long-chain aliphatic group is colored.
It is important to balance the ability of
Furthermore, compounds having various structures have been studied. As a result,
Uses a carboxylic acid compound with a defined structure as a developer
That the above issues can be solved
Was. Of electron-donating color-forming compound by electron-accepting compound
In a reversible thermosensitive coloring composition utilizing a coloring reaction,
In the invention, the compound represented by the following general formula (1) is used as the electron accepting compound.
The carboxylic acid compound described above is used. [0007] Embedded image In the general formula (1), A is R ₁ -X-R ₂ − And represents a long-chain group having 8 or more carbon atoms (here, R ₁
And R ₂ Are both aliphatic hydrocarbon groups.
Is a long-chain aliphatic hydrocarbon group having 8 or more carbon atoms, or
R ₁ And R ₂ At least one of them has a carbon number of 8 or more
The other is an aromatic hydrocarbon group in a chain aliphatic hydrocarbon group,
And these R ₁ And R ₂ Is a hydroxyl group, a halogen atom,
Substitution with an alkoxy group (provided that the hydroxyl group is directly
May be substituted), and X is directly
A direct bond, or -NH-, -CO-, -O-, -S
-, -SO ₂ -, -N = CH-, -CH = N-
X represents a divalent group containing a hetero atom,
When it is present, a divalent short chain having 6 or less carbon atoms is in the middle of the chain.
They may be linked via an aliphatic group or an arylene group.
I), B is a direct bond, or a hydroxyl group, a halogen atom,
Fatty acids having 6 or less carbon atoms which may be substituted with an alkoxy group
Represents a group. Examples include the following:
You. [0008] [0009] Embedded image In addition, further via a hydrocarbon group such as alkylene
A divalent group having one or more of the above groups may be used. That is,
Examples include compounds having the structures shown below. R₁-(X-R_Two)_m− Where R_TwoRepresents a bond other than the above group, and m represents
Represents an integer of 1 to 4. repeated if m is 2 or more
X and R_TwoMay be the same or different
No. As more specific examples of the color developer in the present invention,
The compounds shown in Table 1 are mentioned, but are not limited to these
It is not done. [0010] [Table 1-1][0011] [Table 1-2][0012] [Table 1-3][0013] [Table 1-4][0014] [Table 1-5][0015] [Table 1-6][0016] [Table 1-7][0017] [Table 1-8][0018] [Table 1-9][0019] [Table 1-10][0020] [Table 1-11][0021] [Table 1-12][0022] [Table 1-13][0023] [Table 1-14][0024] [Table 1-15][0025] [Table 1-16][0026] [Table 1-17][0027] [Table 1-18][0028] [Table 1-19][0029] [Table 1-20][0030] [Table 1-21][0031] [Table 1-22][0032] [Table 1-23][0033] [Table 1-24][0034] [Table 1-25][0035] [Table 1-26][0036] [Table 1-27][0037] [Table 1-28][0038] [Table 1-29][0039] [Table 1-30][0040] [Table 1-31][0041] [Table 1-32][0042] [Table 1-33][0043] [Table 1-34][0044] [Table 1-35][0045] [Table 1-36][0046] [Table 1-37][0047] [Table 1-38][0048] [Table 1-39][0049] [Table 1-40][0050] [Table 1-41][0051] [Table 1-42][0052] [Table 1-43][0053] [Table 1-44][0054] [Table 1-45][0055] [Table 1-46][0056] [Table 1-47]The reversible thermosensitive coloring composition of the present invention comprises a basic
By combining the developer and the color former.
It is something that is done. The color former used in the present invention is an electron donor
A colorless or light-colored dye
It is a precursor (leuco dye) and is not particularly limited.
A known compound such as a triphenylmethanephthalide compound
Compounds, fluoran compounds, phenothiazine compounds,
Ico auramine-based compounds, indoliphthalide-based compounds
You can choose from The coloring agent is shown below. As a preferred color former used in the present invention,
There is a compound represented by the following general formula (2) or (3). [0059] Embedded image [0060] Embedded image(However, R_ThreeIs hydrogen or an alkyl group having 1 to 4 carbon atoms, R_Four
Is an alkyl group having 1 to 6 carbon atoms, a cyclohexyl group or
And a phenyl group which may be substituted. For phenyl group
Substituents include alkyl such as methyl and ethyl.
Group, methoxy group, ethoxy group or other alkoxy group or halo
And the like. R_FiveIs hydrogen, alkyl having 1 to 2 carbon atoms
Represents a halogen group, an alkoxy group or a halogen. R₆Is water
, A methyl group, a halogen or an optionally substituted
A group represented by As a substituent for an amino group, for example,
An alkyl group, an optionally substituted aryl group,
Alkyl group, halo group, etc.
Or an alkoxy group) Specific examples of such a color former include, for example, the following compounds
Is mentioned. 2-anilino-3-methyl-6-diethyl
Aminofluoran, 2-anilino-3-methyl-6
(Di-n-butylamino) fluoran, 2-anilino-
3-methyl-6- (Nn-propyl-N-methylamido
G) fluorane, 2-anilino-3-methyl-6- (N
-Isopropyl-N-methylamino) fluoran, 2-
Anilino-3-methyl-6- (N-isobutyl-N-meth
Tylamino) fluoran, 2-anilino-3-methyl-
6- (Nn-amyl-N-methylamino) fluora
2-anilino-3-methyl-6- (N-sec-
Tyl-N-ethylamino) fluoran, 2-anilino-
3-methyl-6- (Nn-amyl-N-ethylamido
G) fluorane, 2-anilino-3-methyl-6- (N
-Isoamyl-N-ethylamino) fluoran, 2-a
Nilino-3-methyl-6- (Nn-propyl-N-i
Sopropylamino) fluoran, 2-anilino-3-meth
Tyl-6- (N-cyclohexyl-N-methylamino)
Fluoran, 2-anilino-3-methyl-6- (N-E
Chill-p-toluidino) fluoran, 2-anilino-3
-Methyl-6- (N-methyl-p-toluidino) fluoro
Orchid, 2- (m-trichloromethylanilino) -3-me
Tyl-6-diethylaminofluoran, 2- (m-tri
Fluoromethylanilino) -3-methyl-6-diethyla
Minofluoran, 2- (m-trifluoromethylanili)
(No) -3-methyl-6- (N-cyclohexyl-N-meth
Tylamino) fluoran, 2- (2,4-dimethylani
Rhino) -3-methyl-6-diethylaminofluoran,
2- (N-ethyl-p-toluidino) -3-methyl-6
-(N-ethylanilino) fluoran, 2- (N-methyl
Ru-p-toluidino) -3-methyl-6- (N-propyl
Le-p-toluizino) fluoran, 2-anilino-6- (Nn-hexyl-
N-ethylamino) fluoran, 2- (o-chloroani
Reno) -6-diethylaminofluoran, 2- (o
Lomoanilino) -6-diethylaminofluoran, 2-
(O-chloroanilino) -6-dibutylaminofluora
, 2- (o-fluoroanilino) -6-dibutylamino
Fluoran, 2- (m-trifluoromethylanilino)-
6-diethylaminofluoran, 2- (p-acetyla
Nilino) -6- (Nn-amyl-Nn-butylamido)
G) fluoran, 2-benzylamino-6- (N-ethyl
Ru-p-toluidino) fluoran, 2-benzylamino
-6- (N-methyl-2,4-dimethylanilino) fur
Oran, 2-benzylamino-6- (N-ethyl-2,
4-dimethylanilino) fluoran, 2-dibenzyla
Mino-6- (N-methyl-p-toluidino) fluora
2-dibenzylamino-6- (N-ethyl-port
Luizino) fluoran, 2- (di-p-methylbenzyl)
Amino) -6- (N-ethyl-p-toluidino) fluor
Run, 2- (α-phenylethylamino) -6- (N-
Ethyl-p-toluidino) fluoran, 2-methylamido
No-6- (N-methylanilino) fluoran, 2-methyl
Ruamino-6- (N-ethylanilino) fluoran, 2
-Methylamino-6- (N-propylanilino) fluoro
Run, 2-ethylamino-6- (N-methyl-propyl
Izino) fluoran, 2-ethylamino-6- (N-E
Chill-p-toluidino) fluoran, 2-methylamino
-6- (N-methyl-2,4-dimethylanilino) fur
Oran, 2-ethylamino-6- (N-ethyl-2,4
-Dimethylanilino) fluoran, 2-dimethylamino
-6- (N-methylanilino) fluoran, 2-dimethyl
Ruamino-6- (N-ethylanilino) fluoran, 2
-Diethylamino-6- (N-methyl-p-toluidine
G) Fluoran, 2-diethylamino-6- (N-ethyl
Ru-p-toluidino) fluoran, 2-dipropylamido
No-6- (N-methyl-anilino) fluoran, 2-di
Propylamino-6- (N-ethyl-anilino) fluoro
Orchid, 2-amino-6- (N-methylanilino) fluoro
Orchid, 2-amino-6- (N-ethylanilino) fluoro
Orchid, 2-amino-6- (N-propylanilino) fur
Oran, 2-amino-6- (N-methyl-p-toluidine
G) fluoran, 2-amino-6- (N-ethyl-p-
Toluidino) fluoran, 2-amino-6- (N-pro
Pill-p-toluidino) fluoran, 2-amino-6-
(N-methyl-p-ethylanilino) fluoran, 2-
Amino-6- (N-ethyl-p-ethylanilino) fur
Oran, 2-amino-6- (N-propyl-p-ethyl
Anilino) fluoran, 2-amino-6- (N-methyl)
-2,4-dimethylanilino) fluoran, 2-amino
-6- (N-ethyl-2,4-dimethylanilino) fur
Oran, 2-amino-6- (N-propyl-2,4-di
Methylanilino) fluoran, 2-amino-6- (N-
Methyl-p-chloroanilino) fluoran, 2-amino
-6- (N-ethyl-p-chloroanilino) fluora
2-amino-6- (N-propyl-p-chloroani
Reno) Fluoran, 2,3-dimethyl-6-dimethylaminop
Luoran, 3-methyl-6- (N-ethyl-p-toluene
Dino) fluorane, 2-chloro-6-diethylaminop
Luoran, 2-bromo-6-diethylaminofluora
2-chloro-6-dipropylaminofluoran, 3
-Chloro-6-cyclohexylaminofluoran, 3-
Bromo-6-cyclohexylaminofluoran, 2-
Rollo-6- (N-ethyl-N-isoamylamino) fur
Oran, 2-chloro-3-methyl-6-diethylamino
Fluoran, 2-anilino-3-chloro-6-diethyl
Aminofluorane, 2- (o-chloroanilino) -3-
Chlor-6-cyclohexylaminofluoran, 2-
(M-fluoromethylanilino) -3-chloro-6-
Diethylaminofluoran, 2- (2,3-dichloroa
Nilino) -3-chloro-6-diethylaminofluora
1,2-benzo-6-diethylaminofluoran,
1,2-benzo-6- (N-ethyl-N-isoamylua
Mino) fluoran, 1,2-benzo-6-dibutylamido
Nofluoran, 1,2-benzo-6- (N-methyl-N
-Cyclohexylamino) fluoran, 1,2-benzo
-6- (N-ethyl-p-toluidino) fluoran,
Other. Other sources preferably used in the present invention
Specific examples of the coloring agent are as follows. 2-anili
No-3-methyl-6- (N-2-ethoxypropyl-N
-Ethylamino) fluoran, 2- (p-chloroanili)
No) -6- (Nn-octylamino) fluoran, 2
-(P-chloroanilino) -6- (Nn-palmityl
Amino) fluoran, 2- (p-chloroanilino) -6
-(Di-n-octylamino) fluoran, 2-benzo
Ilamino-6- (N-ethyl-p-toluidino) fur
Oran, 2- (o-methoxybenzoylamino) -6
(N-methyl-p-toluidino) fluoran, 2-dibe
Ndylamino-4-methyl-6-diethylaminofluor
Orchid, 2-dibenzylamino-4-methoxy-6- (N
-Methyl-p-toluidino) fluoran, 2-benzyl
Amino-4-methyl-6- (N-ethyl-p-toluidine
D) Fluoran, 2- (α-phenylethylamino)-
4-methyl-6-diethylaminofluoran, 2- (p
Toluidino) -3- (t-butyl) -6- (N-methyl
Le-p-toluidino) fluoran, 2- (o-methoxy)
Carbonylanilino) -6-diethylaminofluora
2-acetylamino-6- (N-methyl-propyl)
Izino) fluoran, 3-diethylamino-6- (m-
Trifluoromethylanilino) fluoran, 4-methoxy
-6- (N-ethyl-p-toluidino) fluoran, 2
-Ethoxyethylamino-3-chloro-6-dibutyla
Minofluoran, 2-dibenzylamino-4-chloro-
6- (N-ethyl-p-toluidino) fluoran, 2-
(Α-phenylethylamino) -4-chloro-6-die
Tylaminofluoran, 2- (N-benzyl-p-tol
Fluoromethylanilino) -4-chloro-6-diethyla
Minofluoran, 2-anilino-3-methyl-6-pyro
Lysinofluoran, 2-anilino-3-chloro-6-py
Loridinofluoran, 2-anilino-3-methyl-6-
(N-ethyl-N-tetrahydrofurfurylamino)
Luoran, 2-mesitidino-4 ', 5'-benzo-6-
Diethylaminofluoran, 2- (m-trifluoromethy
Luanilino) -3-methyl-6-pyrrolidinofluora
2- (α-naphthylamino) -3,4-benzo-
4'-bromo-6- (N-benzyl-N-cyclohexyl
Ruamino) fluoran, 2-piperidino-6-diethyl
Aminofluorane, 2- (N-n-propyl-p-tri)
Fluoromethylanilino) -6-morpholinofluora
2- (di-N-p-chlorophenyl-methylamido)
No) -6-pyrrolidinofluoran, 2- (Nn-pro
Pill-m-trifluoromethylanilino) -6-morpho
Linofluoran, 1,2-benzo-6- (N-ethyl-
Nn-octylamino) fluoran, 1,2-benzo
-6-diallylaminofluoran, 1,2-benzo-6
-(N-ethoxyethyl-N-ethylamino) fluora
, Benzoleucomethylene blue 2- ｛3,6
-Bis (diethylamino)}-6- (o-chloroanili
No.) Lactam xanthylbenzoate, 2- {3,6-bis
(Diethylamino)｝-9- (o-chloroanilino) ki
Lactam santyl benzoate, 3,3-bis (p-dimethy
Luanilino) -phthalide, 3,3-bis (p-dimethyl)
Anilino) -6-dimethylaminophthalide (also known as Chris)
Tal violet lactone), 3,3-bis (p
Tylaminophenyl) -6-diethylaminophthalide,
3,3-bis (p-dimethylaminophenyl) -6-c
Lorphthalide, 3,3-bis (p-butylaminophen
Nyl) -phthalide, 3- (2-methoxy-4-dimethyl)
Aminophenyl) -3- (2-hydroxy-4,5-di
Chlorophenyl) phthalide, 3- (2-hydroxy-4)
-Dimethylaminophenyl) -3- (2-methoxy-5
-Chlorophenyl) phthalide, 3- (2-hydroxy-
4-dimethoxyaminophenyl) -3- (2-methoxy
-5-chlorophenyl) phthalide, 3- (2-hydroxy
C-4-dimethylaminophenyl) -3- (2-methoxy)
Ci-5-nitrophenyl) phthalide, 3- (2-hydro
Xy-4-diethylaminophenyl) -3- (2-metho
Xy-5-methylphenyl) phthalide, 3- (2-metho
Xy-4-dimethylaminophenyl) -3- (2-hydrido
Roxy-4-chloro-5-methoxyphenyl) phthaly
, 3,6-bis (dimethylamino) fluorenespiro
(9,3 ')-6'-dimethylaminophthalide, 6'-
Chloro-8'-methoxy-benzoindolino-spiropi
Orchid, 6'-bromo-2'-methoxy-benzoindori
No-spiropyran and others. The reversible thermosensitive coloring composition of the present invention can be heated and
And / or the color developed relatively depending on the cooling rate after heating
And a state in which the color is erased. This basic
The color development / decoloration phenomenon will be described. Figure 1 shows the color development of this composition
It shows the relationship between concentration and temperature. First decolored
When the composition in the state (A) is heated, it begins to melt
Temperature T₁, And a molten color developing state (B) is obtained. Dissolution
When quenched from the melted color development state (B), the color development state is maintained at room temperature
The color can be lowered and a solid color development state (C) is obtained. This
Whether or not a colored state can be obtained depends on the temperature drop from the molten state
In slow cooling, discoloration occurs during the cooling process.
The same decolored state (A) or quenched color development state
A state in which the density is relatively lower than that of (C) is formed. one
On the other hand, when the temperature is raised again in the quenching color development state (C), the color develops
Temperature T lower than temperature_TwoDecoloring occurs (from D to E), here
When the temperature is lowered from, the color returns to the same decolored state (A) as at the beginning. Real
The color development temperature and decolorization temperature are determined by the combination of the color developer and color developer used.
It can be selected according to the purpose because it changes depending on the combination. Ma
The color density in the molten state and the color density after rapid cooling are required.
They are not the same and may be different. In the composition of the present invention, quenching is performed from a molten state.
The color development state (C) obtained in this way is that the developer and the color former are molecules
It is a mixed state in which it can react in contact,
Often forms body condition. In this state, the developer
This is a state in which the color former is aggregated and retains color development.
It is considered that the color formation is stabilized by the formation of the structure.
On the other hand, the decolored state is a state where both are phase-separated. This state
The state is that at least one compound molecule is assembled into a domain
Formed or crystallized, aggregated or crystallized
The color former and developer were separated and stabilized by
It is considered to be a state. In the present invention, in many cases, both
Is more complete due to phase separation and crystallization of the developer
Decoloring occurs. Disappearing from the molten state shown in FIG. 1 by slow cooling
Both color and decoloring by raising the temperature from the colored state
The aggregation structure changes with temperature, causing phase separation and crystallization of the developer.
coming. The composition of the present invention is used as a reversible thermosensitive recording medium.
When using color printing, the formation of color recording
Once heated to the temperature for melting and mixing and then quenched
No. Decoloring is performed by gradually cooling from the heated state and the color development temperature.
Two methods of heating to a slightly lower temperature. Only
These are phase separated from each other or at least one of them
Is the same in that it temporarily holds
You. It is this phase separation or quenching that
This is to prevent the crystallization temperature from being maintained. here
Quenching and slow cooling are relative to one composition.
The boundary varies depending on the combination of the color former and the developer.
Become The ratio between the color former and the developer in the composition is determined by
The appropriate range varies depending on the combination of
Approximately a molar ratio of color developer to developer of 0.1 to 20
And preferably in the range of 0.2 to 10.
You. Color development state with less or more color developer than this range
Is a problem. The reversible thermosensitive recording medium of the present invention is formed on a support.
Provided with a recording layer containing the above composition as a main component
It is. Paper, resin film, synthetic paper, gold
Metal foil, glass or a composite of these, and the recording layer
What is necessary is just a thing which can hold | maintain. The recording layer is formed if the composition of the present invention is present.
Any material may be used, but generally a binder resin
The state in which the color former and the developer are finely and uniformly dispersed is used.
Have been. The color former and the developer form individual particles.
But more preferably dispersed as composite particles
The state is formed. This included a color former and a developer
It can be achieved by melting or melting. This
Such a recording layer is formed by dispersing and dissolving each material in a solvent.
After dissolving and mixing, or mixing each material and solvent
Apply the liquid dispersed or dissolved in the support on the support and dry
This is done by: The color former and developer are microcaps
It can be included in a cell and used. The reversible thermosensitive recording medium of the present invention has
The coating properties and coloring / decoloring properties of the recording layer can be improved or
Controlling additives can be used. These appendages
Additives include, for example, dispersants, surfactant conductive agents, fillers,
Lubricants, antioxidants, light stabilizers, UV absorbers, coloring agents
There are a stabilizing agent and a decoloring accelerator. Binder resin used for forming recording layer
As, for example, polyvinyl chloride, polyvinyl acetate, salt
Vinyl acetate copolymer, ethyl cellulose, poly
Styrene, styrene copolymer, phenoxy resin, poly
Ester, aromatic polyester, polyurethane, polycarbonate
-Carbonate, polyacrylate, polymethacryl
Acid ester, acrylic acid copolymer, maleic acid copolymer
Body, polyvinyl alcohol, modified polyvinyl alcohol
, Hydroxyethylcellulose, carboxymethylcellulose
There are lulose and starches. These binders
The role of the resin is that each material of the composition
To maintain a uniformly dispersed state without
You. Therefore, a resin with high heat resistance is used as the binder resin.
It is preferable to use For example, heat, ultraviolet rays, electron beams
The binder resin may be crosslinked at any point. The reversible thermosensitive recording medium of the present invention basically comprises
Although the above recording layer was provided on a support,
To improve the characteristics as a recording medium, a protective layer, an adhesive layer,
Provide intermediate layer, undercoat layer, backcoat layer, etc.
Can be In printing using a thermal head, heat and pressure
When the surface of the recording layer is deformed due to
There is a case. To prevent this, provide a protective layer on the surface.
Is preferred. For the protective layer, polyvinyl alcohol,
Tylene maleic anhydride copolymer, carboxy-modified polyether
Tylene, melamine-formaldehyde resin, urea-form
In addition to mualdehyde resin, UV curable resin, and electron beam
A cured resin can be used. In addition, ultraviolet rays are contained in the protective layer.
Additives such as absorbents can be included. Improvement of adhesion between recording layer and protective layer, coating of protective layer
Prevention of deterioration of recording layer by cloth, recording layer of additive in protective layer
An intermediate layer between the two to prevent migration to
It is also preferred. Also, protection installed on the recording layer
It is preferable to use a resin with low oxygen permeability for the layer and the intermediate layer.
Good. Prevents oxidation of the color former and developer in the recording layer or
It becomes possible to reduce. Further, in order to make effective use of the applied heat,
Insulating undercoat layer between carrier and recording layer
be able to. Thermal insulation layer is made of organic or inorganic fine hollow particles
Can be formed by coating with a binder resin.
You. Improvement of adhesion between support and recording layer and recording layer on support
Providing an undercoat layer to prevent material penetration
You can also. The intermediate layer and the undercoat layer are formed as described above.
The same resin as the resin for the recording layer can be used. Ma
The protective layer, intermediate layer, recording layer and undercoat layer
Calcium carbonate, magnesium carbonate, titanium oxide, oxidation
Silicon, aluminum hydroxide, kaolin, talc, etc.
A filler can be included. Other, lubricant, circle
A surfactant dispersant or the like may be contained. Color development using the reversible thermosensitive recording material of the present invention
In order to form an image, heat once to the color development temperature
Then, it may be cooled rapidly. Specifically, an example
For example, if you heat for a short time with a thermal head or laser light,
Because the recording layer is locally heated, the heat diffuses immediately and suddenly
Cooling occurs, and the coloring state can be fixed. Meanwhile, decolored
Heating for a relatively long time using an appropriate heat source
Or temporarily heat to a temperature slightly lower than the coloring temperature.
Just do it. Heating for a long time raises the temperature of a wide range of recording media
After that, the cooling is slowed down, and in that process, the discoloration occurs.
Wear. The heating method in this case includes a heat roller and a heat
Or hot air, or use a thermal head
For a long time. [0080] The present invention will be described in more detail with reference to the following examples.
As will be described, the present invention is limited by this embodiment.
is not. All parts and percentages below are by weight.
It is a standard. Embodiment 1 2-anilino-3-methyl-6-diethyl as a color former
The compound shown in Table 1 was used as a developer using
Object No. Carboxylic oxidation compounds represented by 1, 4, 7 and 16
Each of the compositions of the present invention was prepared as follows.
Done. First, the color former and the developer were mixed at a mixing ratio of 1: 3 (mol
) And crushed and mixed in a mortar. thickness
A 1.2 mm glass plate is placed on a hot plate at a temperature of 190.
Heated to ° C. Place a small amount of the above mixture on this glass plate
And melted. All mixtures are colored simultaneously with melting
It became black. Next, cover the molten mixture from above.
Cover with a lath and spread the melt to a uniform thickness.
The whole plate was immersed in the prepared ice water and quenched.
Immediately after cooling, remove from ice water and remove adhering water.
As a result, a thin film-shaped composition of the present invention was obtained. Then, on
The composition in the colored state described above was applied to Yanagimoto Seisakusho's trace melting point analyzer.
Observation while raising the temperature from room temperature at a rate of 4 ° C./min.
As a result, it was found that each of the compositions was approximately 60 ° C. to 140 ° C.
It was confirmed that there was a decolored area up to ° C. In addition,
Hot-heated to 120 ° C.
Discolored instantly when placed on plate. This decolored again
When the composition sample was heated to 190 ° C., it turned black. This
Therefore, the composition of the present invention has a repetitive property of coloring and decoloring.
It was confirmed to have. Embodiment 2 Powder the following composition to a particle size of 1 to 4 μm using a ball mill.
The coating solution for the recording layer was prepared by crushing and dispersing. 2 parts of leuco dye shown in Table 2 8 parts of the developer shown in Table 2 Vinyl chloride-vinyl acetate copolymer 10 parts (VYHH, manufactured by Union Carbide) Methyl ethyl ketone 45 parts 45 parts of toluene A recording layer coating solution having the above composition was coated with a 100 μm thick polyester
Apply using a wire bar on the terfilm and dry
The reversible thermosensitive material of the present invention having a recording layer having a thickness of about 6.0 μm.
A recording medium was manufactured. These recording media are 8 dots / mm
The applied voltage is 13.3 V and the applied
Printing was performed under the condition of a loose width of 1.2 milliseconds to obtain a colored image. This
The optical density of the color image was measured using a Macbeth densitometer RD-918.
Used and measured. Table 2 shows the measurement results. Next,
For about 20 seconds in a thermostat at 100 ° C.
The sample was placed and erased, and the erased density was measured. Erasing each recording medium
Table 2 shows the color density. In addition, the above-mentioned coloring operation and decoloring operation
Was repeated 10 times to check the reversibility of color development.
Of course, it can be confirmed that repetition of coloring and decoloring is possible.
Was. [0083] [Table 2] [0084] As described above in detail and specifically,
The reversible thermosensitive recording composition of the present invention has a stable
It can be formed by repeating a good decolored state.
Reversible thermosensitive recording medium forms high contrast images
And erasure are made possible by an easy operation. The color image is
It is stable under normal use conditions and can be used for repeated recording and erasing.
Rewritable recording media with high durability and high practicality
can get.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the color development / decoloration characteristics of the reversible thermosensitive coloring composition of the present invention. [Description of Signs] A Decoloring state B Melting color developing state C Solid color developing state D Color erasing process E

Continued on the front page (72) Inventor Masaru Shimada 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Kyoji Tsutsui 1-3-6 Nakamagome, Ota-ku, Tokyo Co., Ltd. In Ricoh (56) References JP-A-7-68934 (JP, A) JP-A-9-123617 (JP, A) JP-A-9-176186 (JP, A) JP-A-9-165363 (JP, A) JP-A-9-157242 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/30

Claims (1)

(57) Claims 1. An electron-donating color-forming compound and an electron-accepting compound are used on a support, and are relatively determined by the difference in heating temperature and / or cooling rate after heating. Provide a recording layer containing a color forming composition capable of forming a colored state and a decolored state
A reversible thermosensitive recording medium, wherein a carboxylic acid compound represented by the following general formula (1) is used as the electron-accepting compound . Embedded image In the general formula (1), A is represented by R ₁ —X—R ₂ — and represents a long chain group having 8 or more carbon atoms (here, R ₁
And R ₂ are both aliphatic hydrocarbon groups.
Is a long-chain aliphatic hydrocarbon group having 8 or more carbon atoms, or
At least one of R ₁ and R ₂ has a carbon number of 8 or more.
The other is an aromatic hydrocarbon group in a chain aliphatic hydrocarbon group,
And R ₁ and R ₂ represent a hydroxyl group, a halogen atom,
Substitution with an alkoxy group (provided that the hydroxyl group is directly
May be substituted), and X is directly
A direct bond, or -NH-, -CO-, -O-, -S
_{-, - SO 2 -, -} N = CH -, - CH = consists N-
X represents a divalent group containing a hetero atom,
When it is present, a divalent short chain having 6 or less carbon atoms is in the middle of the chain.
They may be linked via an aliphatic group or an arylene group.
B ) is a direct bond, or a hydroxyl group, a halogen atom,
Fatty acids having 6 or less carbon atoms which may be substituted with an alkoxy group
Represents a group.