JP2000118141A - Reversible heat sensitive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve high-speed eliminating characteristics as well as durability against repeated use by a method wherein a color elimination promoter, having a structure provided with two pieces or more of specified second amide group, is employed in a reversible heat sensitive recording medium having at least a reversible heat sensitive recording layer. SOLUTION: A compound, shown by formulae I, II, III and having two pieces or more of binary amide group, is employed as a color elimination promoter. In respective formulae, R1, R2, R3, R4, and R5 show a saturated or unsaturated hydrocarbon group, which can have a substituent group, while R1 and R2 can form a ring which can be formed through a nitrogen atom or oxygen atom. According to this method, high-speed eliminating property is improved and the heat resistant strength of a recording layer is increased whereby the repeating durability of the recording medium is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermosensitive coloring composition utilizing a coloring reaction between an electron-donating color-forming compound and an electron-accepting compound. The present invention relates to a reversible thermosensitive recording medium capable of forming and erasing.

[0002]

2. Description of the Related Art Conventionally, an electron-donating color-forming compound (hereinafter, referred to as an electron-donating color-forming compound)
Thermal recording media utilizing a color development reaction between a color former or a leuco dye and an electron-accepting compound (hereinafter also referred to as a developer) are widely known, such as facsimile machines, word processors, and scientific measuring instruments. Used in printers. However, these conventional recording media that have been put into practical use all have irreversible color development, and once recorded images cannot be erased and used repeatedly.

On the other hand, according to the patent publication, a recording medium capable of reversibly developing and erasing colors has been proposed. For example, Japanese Patent Application Laid-Open No. Sho 60-1985 uses a combination of gallic acid and phloroglucinol as a color developer. And JP-A-61-237684 using a compound such as phenolphthalein or thymolphthalein as a developer.
JP-A-62-138, in which a recording layer contains a homogeneous solution of a color former, a developer and a carboxylic acid ester.
No. 556, JP-A-62-138568 and JP-A-62-140881, and JP-A-63-17368 using an ascorbic acid dielectric as a developer.
And JP-A-2-188293 and JP-A-2-2-1 using a salt of bis (hydroxyphenyl) acetic acid or gallic acid and a higher aliphatic amine as a color developer.
No. 88294 is disclosed.

Further, the present inventors have disclosed in Japanese Patent Laid-Open No.
No. 4360, an organic phosphoric acid compound, an aliphatic carboxylic acid compound or a phenol compound having a long-chain aliphatic hydrocarbon group is used as a color developer, and the color is developed and decolored by combining this with a leuco dye as a color former. Reversible thermosensitive coloring composition that can easily maintain the color-developed state and the decolored state at room temperature, and can repeat the coloration and decoloration. And a reversible thermosensitive recording medium using the same in the recording layer were proposed. Thereafter, it has been proposed to use a phenol compound having a long-chain aliphatic hydrocarbon group having a specific structure (JP-A-6-210954).

However, if printing and erasing are repeatedly performed under actual use conditions, problems such as a decrease in image density and dents (deformation of a printed portion) may occur, and the color development and development of the developer and leuco dye composition may occur. A reversible thermosensitive recording medium capable of sufficiently exhibiting the decoloring characteristics has not been obtained. This is because printing by the thermal head is performed while applying mechanical force to the recording medium simultaneously with heating to a high temperature, so the structure of the layers that make up the recording medium, such as the recording layer and protective layer, changes, and It is due to being destroyed.

In order to solve such a problem of the recording medium, Japanese Patent Application Laid-Open No. Hei 6-340171 proposes improvement of the repetition durability by adding particles having an average particle diameter of 1.1 times or more the thickness of the recording layer. Further, Japanese Patent Application Laid-Open No. 8-156410 proposes that a protective layer having a specific glossiness and surface roughness is provided to improve head matching, thereby improving repetition durability.

However, even if these recording layers and protective layers are used, it is not possible to completely prevent the destruction of the coating layer during repeated printing / erasing, and dents may occur on the surface of the recording medium due to the multiple use. This causes a printing defect or the like, and has a problem that the number of times of repeated use is substantially limited to a small number.

Further, in actual use, since the ink is often stored under light irradiation, it must have high light resistance and must not deteriorate the coloring and decoloring characteristics due to light.
However, in practical use, when light such as fluorescent light or sunlight shines on the printed image portion and the background portion for a long time, the printed image portion and the background portion are discolored. In particular, the printed image portion is completely erased even if the image is erased. However, there is a problem that an afterimage occurs.

Further, JP-A-9-310128, JP-A-9-272262, and JP-A-9-270563
JP, JP-A-9-300817, JP-A-9-3
No. 00820, etc., it is proposed to provide a high-speed erasing property by adding a specific decoloring accelerator, but the electron-accepting compound and the binder which cause a reversible color tone change are changed. Accordingly, there is a problem that the image density at the time of erasing is practically high, and the erasing start temperature and the erasing temperature range are improved.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reversible thermosensitive recording medium having good high-speed erasing characteristics, and further have good coloring and storage characteristics, and can be used even when repeatedly used. An object of the present invention is to provide a reversible thermosensitive recording medium having good durability without occurrence of dents.

[0011]

Hereinafter, the reversible thermosensitive recording medium of the present invention will be described in detail. The inventors of the present invention used an electron-donating color-forming compound and an electron-accepting compound on a support, and were able to form a relatively colored state by a difference in heating temperature and / or cooling rate after heating. In a reversible thermosensitive recording medium having at least a reversible thermosensitive recording layer containing a thermosensitive composition, the above formulas (1), (2),
It has been found that high-speed erasing characteristics can be obtained by using a decoloring accelerator having a structure having two or more second amide groups represented by (3). As a characteristic, the decoloring accelerator has an effect of further promoting the erasure of the density remaining after the addition of the coloring and decoloring control agent. Further, the present invention is characterized in that a compound represented by the above formula (4), (5) or (6) is used as a decoloring accelerator in the reversible thermosensitive recording layer. It is excellent in high-speed erasability.
Also, deterioration due to repeated use of the recording medium, that is,
It was found that the destruction of the coating film due to multiple printing / erasing was the largest in the recording layer, and that the repetition durability of the recording medium was improved by improving the heat resistance of the recording layer by the decoloring accelerator of the present invention. .

Also, the present invention provides excellent high-speed erasing characteristics by using a compound having two or more secondary amide groups represented by the following formulas (1), (2) or (3) as a decoloring accelerator. It will be. That is, examples of the decoloring accelerator include:
The following structure is mentioned.

[0013]

Embedded image

[0014]

Embedded image

[0015]

Embedded image In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ represent a saturated or unsaturated hydrocarbon group which may have a substituent, and R ₁ and R ₂
May form a ring, and the formed ring may be via a nitrogen atom or an oxygen atom.

More preferably, by using at least one of the compounds represented by the following formulas (4), (5) and (6) as the decoloring accelerator, excellent high-speed erasing characteristics can be obtained. That is, examples of the decolorization accelerator include those having the following structure.

[0017]

Embedded image

[0018]

Embedded image

[0019]

Embedded image Wherein R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ ,
R ₁₄ , R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ represent a saturated or unsaturated hydrocarbon group which may have a substituent, and R ₇ and R ₈ and R ₉ and R ₁₀ form a ring. And the formed ring may be via a nitrogen atom or an oxygen atom. R ₆ , R
Preferred examples of ₁₁ and R ₁₆ include the following.

[0020]

[Table 1] Here, q in the formula represents an integer. R ₇ , R ₈ , R ₉ ,
Preferred examples of R ₁₀ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₅ , R ₁₇ , and R ₁₈ include the following.

[0021]

[Table 2] In the formula, q, q ', q ", and q'" each represent an integer. Hereinafter, preferable structures of the decolorization accelerator used in the present invention will be exemplified, but the present invention is not limited to these compounds. Specific examples include the following compounds as examples of the formula (1).

[0022]

[Table 3] Specific examples of the formula (2) include the following compounds.

[0023]

[Table 4] Specific examples of the formula (3) include the following compounds.

[0024]

[Table 5]

Further, by using a compound having a divalent group containing a hetero atom and an alkyl chain having 6 or more carbon atoms as a coloring / decoloring controlling agent, the coloring / decoloring characteristics can be further improved. Furthermore, in the reversible thermosensitive recording medium of the present invention, the reversible thermosensitive recording layer contains a resin in a cross-linked state, whereby the heat resistance of the recording layer is improved and the repetition durability is improved. In addition, by providing a protective layer mainly composed of the crosslinked resin on the recording layer containing the crosslinked resin, the durability can be further enhanced. The “crosslinked resin” in the present invention means both a resin that has already been crosslinked and a resin that is in a crosslinkable state.

That is, examples of the resin in a cross-linked state include a combination of a cross-linking agent and a resin having an active group which reacts with the cross-linking agent, for example, a resin which can be cross-linked and cured by heat. The resins used herein include, for example, phenoxy resins, polyvinyl butyral resins, cellulose acetate propionate, cellulose acetate butyrate, etc. There is a resin in which a monomer is copolymerized with another monomer.
Copolymer resins include, for example, PVC-based, acrylic-based, styrene-based resins, and specifically, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-hydroxypropyl acrylate copolymer, Examples thereof include a vinyl chloride-vinyl acetate-maleic anhydride copolymer.

Examples of the crosslinking agent for thermal crosslinking include isocyanates, amino resins, phenol resins, amines, epoxy compounds and the like. For example, isocyanates are polyisocyanate compounds having a plurality of isocyanate groups, specifically, hexamethylene diisocyanate (HDI), toluene diisocyanate (TD
I), xylylene diisocyanate (XDI) and the like, and adduct types, burette types, isocyanurate types and blocked isocyanates thereof with trimethylolpropane and the like. The amount of the crosslinking agent to be added to the resin is preferably such that the ratio of the functional group of the crosslinking agent to the number of active groups contained in the resin is 0.01 to 1, and below this, the thermal strength is insufficient, and more than this. When added, it has an adverse effect on the color development / decoloration characteristics. Still further, a catalyst used in this type of reaction may be used as a crosslinking accelerator. Examples of the crosslinking accelerator include tertiary amines such as 1,4-diaza-bicyclo [2,2,2] octane and metal compounds such as organic tin compounds.

Next, examples of monomers used for curing with an electron beam and an ultraviolet ray include the following. Examples of monofunctional monomers Methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, Cyclohexyl methacrylate, benzyl methacrylate, methacrylic acid, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminoethyl methyl methacrylate methyl chloride, diethylaminoethyl methacrylate, glycidyl methacrylate, methacrylic acid Acid tetrahydrofurfuryl, allyl methacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene dimethacrylate Glycol, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane trimethacrylate, methacrylic acid 2-
Ethoxyethyl, 2-ethylhexyl acrylate, 2
-Ethoxyethyl acrylate, 2-ethoxyethoxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, dicyclopentenylethyl acrylate, N-vinylpyrrolidone,
Vinyl acetate and the like.

Examples of difunctional monomers 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol diacrylate, tripropylene Glycol diacrylate, polypropylene glycol diacrylate, bisphenol A ethylene oxide adduct diacrylate, glycerin methacrylate acrylate, diacrylate of neopentyl glycol 2 mol propylene oxide adduct, diethylene glycol diacrylate, polyethylene glycol (400) diacrylate, hydroxypivalin Diacrylate of ester of acid and neopentyl glycol,
2,2-bis (4-acryloxydiethoxyphenyl)
Propane, diacrylate of neopentyl glycol diadipate, diacrylate of ε-caprolactone adduct of neopentyl glycol hydroxypivalate, 2
-(2-hydroxy-1,1-dimethylethyl) -5-
Hydroxymethyl-5-ethyl-1,3-dioxane diacrylate, tricyclodecane dimethylol diacrylate, ε-caprolactone adduct of tricyclodecane dimethylol diacrylate, diacrylate of glycidyl ether of 1,6-hexanediol, etc. .

Examples of polyfunctional monomers Trimethylolpropane triacrylate, glycerin propylene oxide addition acrylate, trisacryloyloxyethyl phosphate, pentaerythritol acrylate, triacrylate of a 3 mole addition of propylene oxide of trimethylolpropane, dipentaerythritol. Polyacrylate, polyacrylate of caprolactone adduct of dipentaerythritol,
Dipentaerythritol triacrylate propionate, hydroxypivalaldehyde-modified dimethylolpropyne triacrylate, tetraacrylate dipentaerythritol propionate, ditrimethylolpropane tetraacrylate, pentaacrylate dipentaerythritol propionate, pentaacrylate dipentaerythritol hexaacrylate, Ε-caprolactone adduct of dipentaerythritol hexaacrylate and the like.

Examples of oligomers Bisphenol A-diepoxyacrylic acid adducts and the like.

When crosslinking is carried out using ultraviolet rays, the following photopolymerization initiator and photopolymerization accelerator are used. Examples include isobutyl benzoin ether, isopropyl benzoin ether, benzoin ethyl ether,
Benzoin ethers such as benzoin methyl ether.
Α-acyloxime esters such as 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime. Benzyl ketals such as 2,2-dimethoxy-2-phenylacetophenone, benzyl and hydroxycyclohexyl phenol ketone. Acetophenone dielectrics such as diethoxyacetophenone and 2-hydroxy-2-methyl-1-phenylpropan-1-one; Ketones such as benzophenone, 1-chlorothioxanthone, 2-chlorothioxanthone, isopropylthioxanthone, 2-methylthioxanthone, 2-methylthioxanthone and 2-chlorobenzophenone are exemplified. These photopolymerization initiators are used alone or in combination of two or more. The addition amount is 0.005 to 1 part by weight of the crosslinking agent.
To 1.0 parts by weight, more preferably 0.01 to
0.5 parts by weight.

As the photopolymerization accelerator, there are aromatic tertiary amines and aliphatic amines. Specific examples include p-dimethylaminobenzoic acid isoamyl ester and p-dimethylaminobenzoic acid ethyl ester. These photopolymerization accelerators are used alone or in combination of two or more. The amount of addition is 0.1 to 1 part by weight of the photopolymerization initiator.
It is preferably 1 to 5 parts by weight, more preferably 0.3 to 3 parts by weight.

The light source for the ultraviolet irradiation used in the present invention includes a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, a flash lamp, and the like. A light source having an emission spectrum corresponding to the above may be used. As the UV irradiation conditions, the lamp output and the transport speed may be determined according to the irradiation energy required for crosslinking the resin. In addition, as the electron beam irradiation device, it is only necessary to select a scanning type or a non-scanning type according to the purpose such as an irradiation area, an irradiation dose, and the like, and as irradiation conditions, according to a dose necessary for crosslinking a resin, The electron flow, irradiation width, and transport speed may be determined.

Further, by using a compound represented by the following formula (7) as a coloring and decoloring controlling agent used in the present invention, excellent storage characteristics and high-speed erasing characteristics can be obtained. Examples of the coloring / decoloring controlling agent include those having the following structure.

[0036]

Embedded image In the formula, X ₁ , X ₂ and X ₃ represent a group containing a hetero atom,
R ₂₁ , R ₂₂ and R ₂₃ represent a group having 1 to 22 carbon atoms. Further, l, m and o each independently represent 0 or 1, and n represents an integer of 0 to 4. Where l, m, n
And o are never 0 at the same time. Further, R ₃ and X ₂ repeated when n is 2 or more may be the same or different. R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄
May contain a heterocyclic ring. More preferably, R ₂₁ ,
And the sum of the carbon atoms in R ₂₂ and R ₂₃ is 8 or more. R ₂₁ , R ₂₂
And R ₂₃ represent a hydrocarbon group which may have a substituent, which may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, or a hydrocarbon group composed of both of them. Further, the aliphatic hydrocarbon group may be linear or branched, and may have an unsaturated bond. Examples of the substituent attached to the hydrocarbon group include a hydroxyl group, a halogen, and an alkoxy group. Further, when the sum of the number of carbon atoms of R ₂₁ , R ₂₂ , R ₂₃ and R ₂₄ is 7 or less, the stability of color development and the decoloring property decrease, so the number of carbon atoms is preferably 8 or more, more preferably 11 or more. preferable. Preferred examples of R ₂₁ and R ₂₃ include those shown in Table 6.

[0037]

[Table 6]

Preferred examples of R ₂₂ , R ₂₃ and R ₂₄ include those shown in Table 7.

[0039]

[Table 7] In the formula, q, q ', q ", and q"' are each R ₂₁ ,
Represents an integer that satisfies the carbon number of R ₂₂ and R ₂₃ .

When X ₁ and X ₃ are at the terminal position of the structural formula, they preferably represent a group having at least one of the groups shown in Table 8.

[0041]

[Table 8]

Examples thereof are shown in Table 9.

[0043]

[Table 9]

X ₁ and X ₂ each represent a divalent group containing a hetero atom, preferably a divalent group having at least one of the groups shown in Table 10.

[0045]

[Table 10]

Examples thereof are shown in Table 11.

[0047]

[Table 11]

The preferred structures of the coloring and decoloring controlling agents used in the present invention are illustrated below, but the present invention is not limited to these compounds.

[0049]

Embedded image

[0050]

Embedded image

[0051]

Embedded image R ₂₁ , R ₂₂ , R ₂₃ , R ₂₄ , X ₁ , X ₂ and X ₃ each represent the same groups as described above. N is 0 to 4
R ₂₃ , which is repeated when n is 2 or more,
X ₂ may be the same or different. further,
m represents 0 or 1. However, n and m are not 0 at the same time. Further, particularly preferred structures include the following.

[0052]

Embedded image

[0053]

Embedded image

[0054]

Embedded image

[0055]

Embedded image

[0056]

Embedded image

[0057]

Embedded image

Specific examples of the coloring and decoloring controlling agents used in the present invention include, for example, those of the formula (15) shown in Table 12.
The compound of. Further, the same compounds can be mentioned for the formula (16).

[0059]

[Table 12]

As a more specific example, for example, in Table 12,

[0061]

Embedded image and

[0062]

Embedded image Examples of the compound represented by are the compounds shown in Table 13.

[0063]

[Table 13]

Further, according to the present invention, the use of a phenolic compound represented by the following formula as a color developer can provide a good image contrast.

[0065]

Embedded image In the formula, X ₄ represents a divalent group containing a hetero atom or a direct bond, and X ₅ represents a divalent group containing a hetero atom. R
₂₈ represents a divalent hydrocarbon group, and R ₂₉ represents a group having 1 to 2 carbon atoms.
2 represents a hydrocarbon group. P represents an integer of 0 to 4 and R ₂₈ and X ₅ repeated when p is 2 to 4
May be the same or different. Q ₁ represents an integer of 1 to 3.

Specifically, R ₂₈ and R ₂₉ each represent a hydrocarbon group which may have a substituent, which may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. Or a hydrocarbon group composed of Further, the aliphatic hydrocarbon group may be linear or branched, and may have an unsaturated bond. As a substituent attached to the hydrocarbon group,
There are a hydroxyl group, a halogen, an alkoxy group and the like. Note that R ₂₈
May be a direct bond. If the sum of the carbon numbers of R ₂₈ and R ₂₉ is 7 or less, the stability of color development and the decoloring property decrease, so that
The number of carbon atoms is preferably 8 or more, more preferably 11 or more. Preferred examples of R ₂₈ include those shown in Table 14 in addition to the direct bond.

[0067]

[Table 14] Preferred examples of R ₂₉ include those shown in Table 15.

[0068]

[Table 15]

In the formula, q, q ', q "and q"' each represent an integer satisfying the carbon number of R ₂₈ and R ₂₉ described above. X ₄ and X ₅ each represent a divalent group containing a hetero atom, preferably a divalent group having at least one group shown in Table 16.

[0070]

[Table 16] An example is shown in Table 17.

[0071]

[Table 17]

Particularly preferred examples of the phenol compound used in the present invention include a compound represented by the following formula.

[0073]

Embedded image

[0074]

Embedded image

[0075]

Embedded image

[0076]

Embedded image

[0077]

Embedded image

[0078]

Embedded image

[0079]

Embedded image

[0080]

Embedded image R, r ', and s in the formula each independently represent an integer that satisfies the carbon number of R ₂₈ or R ₂₉ .

More specific examples of the phenol compound in the present invention include, for example, compounds shown in Table 18 below as examples of the formula (19). Further, other compounds represented by the formulas (18) and (20) to (25) are also similar to these and specific examples. However, the present invention is not limited to these.

[0082]

[Table 18-1]

[0083]

[Table 18-2]

[0084]

[Table 18-3]

[0085]

[Table 18-4]

Further, more specific phenol compounds include, for example, the following. Specific examples of the compound represented by the following formula in Table 18 are shown in Table 1 as examples.
No. 9 The same applies to compounds represented by other formulas in Table 18. However, the present invention is not limited to these.

[0087]

Embedded image

[0088]

[Table 19]

Further, according to the present invention, a protective layer using a cross-linked resin may be provided on the recording layer, and the cross-linked resin may be the aforementioned thermosetting resin, ultraviolet curable resin, An electronic curable resin or the like is used. Thereby, the head matching property at the time of printing is improved, and the repetition durability is further improved. The protective layer may contain additives such as an ultraviolet absorber, an inorganic or / and organic filler, and a lubricant.

In the present invention, another developer can be used in combination with the phenolic compound. As a color developing agent to be used in combination, as disclosed in Japanese Patent Application Laid-Open No. 5-124360 together with typical examples of a phosphoric acid compound having a long-chain hydrocarbon group and a fatty acid compound phenol compound, a coloring agent is present in the molecule. A compound having both a structure capable of developing color and a structure controlling the cohesion between molecules can be used in combination.

Hereinafter, the color developer used in the present invention will be specifically exemplified. Examples of the organic phosphoric acid developer include the following compounds. Dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, docosylphosphonic acid, tetracosylphosphonic acid, ditetradecyl phosphate, dihexadecyl phosphate, phosphoric acid Dioctadecyl ester, dieicosyl phosphate, dibehenyl phosphate, and the like.

Examples of the aliphatic carboxylic compound include the following compounds. 2-hydroxytetradecanoic acid, 2-hydroxyhexadecanoic acid, 2-hydroxyoctadecanoic acid, 2-hydroxyeicosanoic acid, 2-hydroxydocosanoic acid, 2-bromohexadecanoic acid, 2-bromooctadecanoic acid, 2-bromoeicosanoic acid 2-bromodocosanoic acid, 3-bromooctadecanoic acid, 3-bromodocosanoic acid, 2,3-dibromooctadecanoic acid,
Fluorododecanoic acid, 2-fluorotetradecanoic acid, 2
-Fluorohexadecanoic acid, 2-fluorooctadecanoic acid, 2-fluoroeicosanoic acid, 2-fluorodocosanoic acid, 2-iodohexadecanoic acid, 2-iodooctadecanoic acid, 3-iodohexadecanoic acid, 3-iodooctadecanoic acid, par Fluorooctadecanoic acid and the like.

As the aliphatic dicarboxylic acid and tricarboxylic acid compounds, the following compounds can be exemplified. 2-
Dodecyloxysuccinic acid, 2-tetradecyloxysuccinic acid, 2-hexadecyloxysuccinic acid, 2-octadecyloxysuccinic acid, 2-eicosyloxysuccinic acid,
2-dodecylthiosuccinic acid, 2-tetradecylthiosuccinic acid, 2-hexadecylthiosuccinic acid, 2-octadecylthiosuccinic acid, 2-eicosylthiosuccinic acid, 2-docosylthiosuccinic acid, 2-tetracosylthiosuccinic acid,
2-hexadecyldithiosuccinic acid, 2-octadecyldithiosuccinic acid, 2-eicosyldithiosuccinic acid, dodecylsuccinic acid, tetradecylsuccinic acid, pentadecylsuccinic acid, hexadecylsuccinic acid, octadecylsuccinic acid,
Eicosyl succinic acid, docosyl succinic acid, 2,3-dihexadecyl succinic acid, 2,3-dioctadecyl succinic acid, 2-methyl-3-hexadecyl succinic acid, 2-methyl-3-octadecyl succinic acid, 2-octadecyl-3
-Hexadecylsuccinic acid, hexadecylmalonic acid, octadecylmalonic acid, eicosylmalonic acid, docosylmalonic acid, dihexadecylmalonic acid, dioctadecylmalonic acid, didocosylmalonic acid, methyloctadecylmalonic acid, 2-hexadecylglutaric acid, 2- Octadecyl glutaric acid, 2-eicosyl glutaric acid, docosyl glutaric acid, 2-pentadecyl adipic acid, 2-octadecyl adipic acid, 2-eicosyl adipic acid, 2-docosyl adipic acid, 2-hexadecanoyloxypropane −
1,2,3-tricarboxylic acid, 2-octadecanoyloxypropane-1,2,3-tricarboxylic acid and the like.

As the leuco dye, conventionally known leuco dyes can be arbitrarily used, and the following compounds are particularly preferably used alone or in combination.

[0095]

Embedded image (Wherein, R ₃₃ and R ₃₄ represent a lower alkyl group, an aryl group which may be substituted, or a hydrogen atom, and R ₃₃ and R ₃₄ may combine with each other to form a ring. R ₃₅ is a lower alkyl group) group, a halogen atom or a hydrogen atom, also, R ₃₆
Is a lower alkyl, a halogen atom, a hydrogen atom or a formula (2
The substituted anilino group represented by 7) is shown. )

[0096]

Embedded image (Wherein, R ₃₇ represents a lower alkyl group or a hydrogen atom,
X ₁₃ represents a lower alkyl group or a halogen atom. n represents an integer of 0 to 3. )

[0097]

Embedded image (In the formula, R ₃₈ , R ₃₉ , R ₄₀ , and R ₄₁ represent an alkyl group or a hydrogen atom, and R ₄₂ represents an alkyl group, an alkoxy group, or a hydrogen atom.)

[0098]

Embedded image (In the formula, R ₄₃ , R ₄₄ , R ₄₅ and R ₄₆ represent a lower alkyl group or a hydrogen atom. R ₄₇ and R ₄₈ represent an alkyl group, an alkoxy group or a hydrogen atom.)

The following are examples of leuco dyes used in the present invention, but the present invention is not limited thereto. 2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-di (n-butylamino) fluoran, 2-anilino-3-methyl-
6- (Nn-propyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N-isopropyl-N-methylamino) fluoran, 2-anilino-3
-Methyl-6- (N-isobutyl-N-methylamino)
Fluoran, 2-anilino-3-methyl-6- (Nn
-Amyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N-sec-butyl-N-methylamino) fluoran, 2-anilino-3-methyl-6
-(Nn-amyl-N-ethylamino) fluoran,
2-anilino-3-methyl-6- (N-iso-amyl-N-ethylamino) fluoran, 2-anilino-3-
Methyl-6- (NN-propyl-N-isopropylamino) fluoran, 2-anilino-3-methyl-6
(N-cyclohexyl-N-methylamino) fluoran, 2-anilino-3-methyl-6- (N-ethyl-p
-Toluidino) fluoran, 2-anilino-3-methyl-6- (N-methyl-p-toluidino) fluoran,

2- (m-trichloromethylanilino)-
3-methyl-6-diethylaminofluoran, 2- (m
-Trifluoromethylanilino) -3-methyl-6-diethylaminofluoran, 2- (m-trichloromethylanilino) -3-methyl-6- (N-cyclohexyl-
N-methylamino) fluoran, 2- (2,4-dimethylanilino) -3-methyl-6-diethylaminofluoran, 2- (N-ethyl-p-toluidino) -3-methyl-6- (N- Ethylanilino) fluoran, 2- (N
-Ethyl-p-toluidino) -3-methyl-6- (N-
Propyl-p-toluidino) fluoran, 2-anilino-6- (Nn-hexyl-N-ethylamino) fluoran, 2- (o-chloroanilino) -6-diethylaminofluoran, 2- (o-chloroanilino)- 6-dibutylaminofluoran, 2- (m-trifluoromethylanilino) -6-diethylaminofluoran, 2,3-
Dimethyl-6-dimethylaminofluoran, 3-methyl-6- (N-ethyl-p-toluidino) fluoran, 2
-Chloro-6-diethylaminofluoran, 2-bromo-6-diethylaminofluoran, 2-chloro-6-dipropylaminofluoran, 3-chloro-6-cyclohexylaminofluoran, 3-bromo-6-cyclohexylamino Fluoran, 2-chloro-6- (N-ethyl-N-isoamylamino) fluoran, 2-chloro-3
-Methyl-6-diethylaminofluoran, 2-anilino-3-chloro-6-diethylaminofluoran, 2-
(O-chloroanilino) -3-chloro-6-cyclohexylaminofluoran, 2- (m-trifluoromethylanilino) -3-chloro-6-diethylaminofluoran, 2- (2,3-dichloroanilino) -3-chloro-
6-diethylaminofluoran,

1,2-benzo-6-diethylaminofluoran, 3-diethylamino-6- (m-trifluoromethylanilino) fluoran, 3- (1-ethyl-2-
Methylindol-3-yl) -3- (2-ethoxy-
4-diethylaminophenyl) -4-azaphthalide, 3
-(1-ethyl-2-methylindol-3-yl)-
3- (2-ethoxy-4-diethylaminophenyl)-
7-azaphthalide, 3- (1-octyl-2-methylindol-3-yl) -3- (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3- (1-
Ethyl-2-methylindol-3-yl) -3- (2
-Methyl-4-diethylaminophenyl) -4-azaphthalide, 3- (1-ethyl-2-methylindole-3)
-Yl) -3- (2-methyl-4-diethylaminophenyl) -7-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylaminophenyl) -4-azaphthalide , 3- (1-ethyl-
2-methylindol-3-yl) -3- (4-N-n
-Amyl-N-methylaminophenyl) -4-azaphthalide, 3- (1-methyl-2-methylindole-3-
Yl) -3- (2-hexyloxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis (2-
Ethoxy-4-diethylaminophenyl) -4-azaphthalide, 3,3-bis (2-ethoxy-4-diethylaminophenyl) -7-azaphthalide and the like.

As the color former used in the present invention, in addition to the above-mentioned fluoran compounds and azaphthalide compounds, conventionally known leuco dyes can be used alone or in combination. The coloring agent is shown below. 2- (p-acetylanilino) -6- (Nn-amyl-Nn-butylamino) fluoran, 2-benzylamino-6- (N-ethyl-p-toluidino) fluoran, 2-benzylamino -6- (N-methyl-2,4-dimethylanilino) fluoran, 2-benzylamino-6- (N-ethyl-2,
4-dimethylanilino) fluoran, 2-benzylamino-6- (N-methyl-p-toluidino) fluoran,
2-benzylamino-6- (N-ethyl-p-toluidino) fluoran, 2- (di-p-methylbenzylamino) -6- (N-ethyl-p-toluidino) fluoran, 2- (α-phenylethyl) Amino) -6- (N-ethyl-p-toluidino) fluoran,

2-methylamino-6- (N-methylanilino) fluoran, 2-methylamino-6- (N-ethylanilino) fluoran, 2-methylamino-6- (N
-Propylanilino) fluoran, 2-ethylamino-
6- (N-methyl-p-toluidino) fluoran, 2-
Methylamino-6- (N-methyl-2,4-dimethylanilino) fluoran, 2-ethylamino-6- (N-ethyl-2,4-dimethylanilino) fluoran, 2-dimethylamino-6- ( (N-methylanilino) fluoran, 2-dimethylamino-6- (N-ethylanilino)
Fluoran, 2-diethylamino-6- (N-methyl-
p-Toluidino) fluoran, 2-diethylamino-6
-(N-ethyl-p-toluidino) fluoran, 2-dipropylamino-6- (N-methylanilino) fluoran, 2-dipropylamino-6- (N-ethylanilino) fluoran,

2-amino-6- (N-methylanilino)
Fluoran, 2-amino-6- (N-ethylanilino)
Fluoran, 2-amino-6- (N-propylanilino) fluoran, 2-amino-6- (N-methyl-p-
Toluidino) fluoran, 2-amino-6- (N-ethyl-p-toluidino) fluoran, 2-amino-6
(N-propyl-p-toluidino) fluoran, 2-amino-6- (N-methyl-p-ethylanilino) fluoran, 2-amino-6- (N-ethyl-p-ethylanilino) fluoran, 2-amino-6 -(N-propyl-
p-ethylanilino) fluoran, 2-amino-6-
(N-methyl-2,4-dimethylanilino) fluoran, 2-amino-6- (N-ethyl-2,4-dimethylanilino) fluoran, 2-amino-6- (N-propyl-2,4 -Dimethylanilino) fluoran, 2-amino-6- (N-methyl-p-chloroanilino) fluoran, 2-amino-6- (N-ethyl-p-chloroanilino) fluoran, 2-amino-6- (N- Propyl-p
-Chloroanilino) fluorane, 1,2-benzo-6-
(N-ethyl-N-isoamylamino) fluoran,
1,2-benzo-6-dibutylaminofluoran,
2-benzo-6- (N-methyl-N-cyclohexylamino) fluoran, 1,2-benzo-6- (N-ethyl-N-toluidino) fluoran and the like.

Specific examples of other color formers preferably used in the present invention are as follows. 2-anilino-3-methyl-6- (N-2-ethoxypropyl-N-
Ethylamino) fluoran, 2- (p-chloroanilino) -6- (Nn-octylamino) fluoran, 2
-(P-chloroanilino) -6- (Nn-palmitylamino) fluoran, 2- (p-chloroanilino) -6
-(Di-n-octylamino) fluoran, 2-benzoylamino-6- (N-ethyl-p-toluidino) fluoran, 2- (o-methoxybenzoylamino) -6
(N-methyl-p-toluidino) fluoran, 2-dibenzylamino-4-methyl-6-diethylaminofluoran, 2-dibenzylamino-4-methoxy-6- (N
-Methyl-p-toluidino) fluoran, 2-dibenzylamino-4-methyl-6- (N-ethyl-p-toluidino) fluoran,

2- (α-phenylethylamino) -4-
Methyl-6-diethylaminofluoran, 2- (p-toluidino) -3- (t-butyl) -6- (N-methyl-
p-Toluidino) fluoran, 2- (o-methoxycarbonylamino) -6-diethylaminofluoran, 2-
Acetylamino-6- (N-methyl-p-toluidino)
Fluoran, 4-methoxy-6- (N-ethyl-p-toluidino) fluoran, 2-ethoxyethylamino-3
-Chloro-6-dibutylaminofluoran, 2-dibenzylamino-4-chloro-6- (N-ethyl-p-toluidino) fluoran, 2- (α-phenylethylamino) -4-chloro-6-diethylamino Fluoran, 2
-(N-benzyl-p-trifluoromethylanilino)
-4-chloro-6-diethylaminofluoran, 2-anilino-3-methyl-6-pyrrolidinofluoran, 2-
Anilino-3-chloro-6-pyrrolidinofluoran, 2
-Anilino-3-methyl-6- (N-ethyl-N-tetrahydrofurfurylamino) fluoran,

2-mesidino-4 ', 5'-benzo-6-
Diethylaminofluoran, 2- (m-trifluoromethylanilino) -3-methyl-6-pyrrolidinofluoran, 2- (α-naphthylamino) -3,4benzo-4 ′
-Bromo-6- (N-benzyl-N-cyclohexylamino) fluoran, 2-piperidino-6-diethylaminofluoran, 2- (Nn-propyl-p-trifluoromethylanilino) -6-morpholinofur Oran,
2- (di-N-p-chlorophenyl-methylamino)-
6-pyrrolidinofluoran, 2- (Nn-propyl-
m-trifluoromethylanilino) -6-morpholinofluoran, 1,2-benzo-6- (N-ethyl-N-
n-octylamino) fluoran, 1,2-benzo-6
-Diallylaminofluoran, 1,2-benzo-6-
(N-ethoxyethyl-N-ethylamino) fluoran,

Benzoleucomethylene blue 2- [3,6-bis (diethylamino) -7- (o-chloroanilino) xanthyl] lactam benzoate, 2-
[3,6-Diethylamino-9- (o-chloroanilino) xanthyl] lactam benzoate, 3,3-bis (p
-Dimethylaminophenyl) -phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone),
3,3-bis- (p-dimethylaminophenyl) -6
Diethylaminophthalide, 3,3-bis- (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis- (p-dibutylaminophenyl) phthalide, 3-
(2-methoxy-4-dimethylaminophenyl) -3-
(2-hydroxy-4,5-dichlorophenyl) phthalide, 3- (2-hydroxy-4-dimethylaminophenyl) -3- (2-methoxy-5-chlorophenyl) phthalide, 3- (2-hydroxy-4-dimethoxy) Aminophenyl) -3- (2-methoxy-5-chlorophenyl)
Phthalide, 3- (2-hydroxy-4-dimethylaminophenyl) -3- (2-methoxy-5-nitrophenyl) phthalide, 3- (2-hydroxy-4-diethylaminophenyl) -3- (2-methoxy- 5-methylphenyl) phthalide, 3- (2-methoxy-4-dimethylaminophenyl) -3- (2-hydroxy-4-chloro-
5-methoxyphenyl) phthalide, 3,6-bis (dimethylamino) fluorenespiro (9,3 ')-6'-dimethylaminophthalide, 6'-chloro-8'-methoxy-benzoindolino-spiropyran, 6 '-Bromo-
2'-methoxy-benzoindolino-spiropyran and the like.

The reversible thermosensitive recording medium of the present invention can form a relatively colored state and a decolored state depending on the heating temperature and / or the cooling rate after heating. The basic coloring / decoloring phenomenon of the composition comprising the color former and the developer used in the present invention will be described. FIG. 1 shows the relationship between the color density and the temperature of the recording medium. Introduction gradually heated the recording medium in the decolored state (A), a molten colored state occurs coloration at temperatures T ₁ begins to melt (B).
When the color is rapidly cooled from the melted color development state (B), the temperature can be lowered to room temperature while maintaining the color development state, and a solid color development state (C) is obtained.
Whether or not this color-developed state is obtained depends on the rate of temperature decrease from the molten state. In the case of slow cooling, decoloration occurs in the process of temperature decrease, and the same decolored state (A) or quenched color state (C) as at the beginning. A) is formed with a relatively lower concentration. On the other hand, rapidly cooled colored state (C) is again raised gradually and discoloring occurs at a lower temperature T ₂ than the coloring temperature (E from D), returns the beginning when the temperature decreases from here to the same decolored state (A). The actual color forming temperature and color erasing temperature can be selected according to the purpose because they vary depending on the combination of the color developer and the color developing agent used. In addition, the density in the molten color development state and the color development density after quenching do not always match, and may differ.

In the recording medium of the present invention, the color-developed state (C) obtained by quenching from the molten state is a state in which the developer and the color-developing agent are mixed in a state in which molecules can contact and react with each other. It often forms a state. This state is a state in which the color developer and the color forming agent aggregate to maintain the color development, and it is considered that the color formation is stabilized by the formation of the aggregate structure. On the other hand, the decolored state is a state where both are phase-separated. This state is a state in which molecules of at least one compound are aggregated to form a domain or crystallized, and it is considered that the color former and the developer are separated and stabilized by aggregation or crystallization. Can be In the present invention, in many cases,
More complete decoloring occurs due to phase separation of the two and crystallization of the developer. In the decoloring by slow cooling from the molten state and the decoloring by raising the temperature from the colored state shown in FIG. 1, the cohesive structure changes at this temperature, and phase separation and crystallization of the developer occur.

The formation of color recording on the reversible thermosensitive recording medium of the present invention may be performed by heating the mixture to a temperature at which it is melted and mixed by a thermal head or the like, and then rapidly cooling the mixture. The decoloring is performed by two methods: a method of gradually cooling from a heating state and a method of heating to a temperature slightly lower than a coloring temperature. However, they are the same in the sense that they both phase-separate or temporarily hold at a temperature at which at least one crystallizes. The rapid cooling in the formation of a color-developed state is for preventing the phase separation temperature or the crystallization temperature from being maintained. Here, the rapid cooling and the slow cooling are relative to one composition, and the boundary varies depending on the combination of the color former and the developer.

The appropriate range of the ratio of the color former to the color developer varies depending on the combination of the compounds used, but the developer is generally in the range of 0.1 to 20 with respect to the color former 1 in a molar ratio. Preferably it is in the range of 0.2 to 10. If the amount of the developer is smaller or larger than this range, the density of the color-developed state is reduced, which is problematic. Further, the ratio of the decoloring accelerator and the coloring / decoloring control agent is preferably from 0.1% by weight to 300% by weight, more preferably from 3% by weight to 100% by weight, based on the developer. Further, the color former and the developer can be used by being encapsulated in microcapsules.

The ratio of the color-forming component and the resin in the recording layer is preferably from 0.1 to 10 with respect to the color-forming component 1. If the ratio is less than this, the strength of the recording layer is insufficient. It will be a problem. For the formation of the recording layer, a coating solution prepared by uniformly mixing a mixture of the above-described developer, color former, color erasure accelerator, color erasure controller and resin in a crosslinked state and a coating solution solvent is used. Used. Specific examples of the solvent used for preparing the coating liquid include water; alcohols such as methanol, ethanol, isopropanol, n-butanol, and methyl isocarbinol; acetone, 2-butanone, ethyl amyl ketone, diacetone alcohol;
Ketones such as isophorone and cyclohexanone; N, N
Amides such as -dimethylformamide, N, N-dimethylacetamide; diethyl ether, isopropyl ether, tetrahydrofuran, 1,4-dioxane,
Ethers such as 3,4-dihydro-2H-pyran; 2
-Methoxyethanol, 2-ethoxyethanol, 2-
Glycol ethers such as butoxyethanol and ethylene glycol dimethyl ether; glycol ether acetates such as 2-methoxyethyl acetate, 2-ethoxyethyl acetate and 2-butoxyethyl acetate; methyl acetate, ethyl acetate, isobutyl acetate, amyl acetate and ethyl lactate , Esters such as ethylene carbonate; aromatic hydrocarbons such as benzene, toluene and xylene; hexane, heptane, iso-octane,
Aliphatic hydrocarbons such as cyclohexane; halogenated hydrocarbons such as methylene chloride, 1,2-dichloroethane, dichloropropane and chlorobenzene; sulfoxides such as dimethylsulfoxide; N-methyl-2-pyrrolidone, N-octyl- Examples thereof include pyrrolidones such as 2-pyrrolidone.

The coating liquid can be prepared using a known coating liquid dispersing apparatus such as a paint shaker, a ball mill, an attritor, a three-roll mill, a Keddy mill, a sand mill, a dyno mill, and a colloid mill. In addition, each material may be dispersed in a solvent using the above-described coating liquid dispersion device, or each material may be dispersed alone in the solvent and mixed. Further, it may be dissolved by heating and precipitated by rapid cooling or slow cooling.

The coating method for providing the recording layer is not particularly limited, and may be blade coating, wire bar coating, spray coating, air knife coating, bead coating, curtain coating, gravure coating, kiss coating, Known methods such as reverse roll coating, dip coating, and die coating can be used.

The method for drying and curing the recording layer is as follows:
A hardening treatment is performed if necessary. As long as it can be crosslinked by heat, it may be performed at a relatively high temperature for a short time using a high-temperature bath or the like, or may be heat-treated at a relatively low temperature for a long time. Also,
Known curing devices may be used for ultraviolet curing and electron beam curing. For example, as a light source at the time of ultraviolet irradiation, there are a water source lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, a flash lamp, and the like. A light source having the same may be used. As the UV irradiation conditions, the lamp output and the transport speed may be determined according to the irradiation energy required for crosslinking the resin. Further, as the electron beam irradiation device, any of a scanning type and a non-scanning type may be selected according to the purpose such as an irradiation area and an irradiation dose, and the irradiation condition may be selected according to a dose required for crosslinking the resin. The flow, irradiation width, and transport speed may be determined. The thickness of the recording layer is 1 to 20
The range of μm is preferred, and more preferably 3 to 10 μm.

The support of the reversible thermosensitive recording medium of the present invention is paper, resin film, synthetic paper, metal foil, glass or a composite thereof, and may be any as long as it can hold the recording layer.

In the reversible thermosensitive recording medium of the present invention, an additive for improving or controlling the coating characteristics and the coloring and decoloring characteristics of the recording layer can be used, if necessary. These additives include, for example, surfactants, conductive agents, fillers, antioxidants, light stabilizers, color stabilizers, and the like.

The reversible thermosensitive recording medium of the present invention basically comprises a support provided with a recording layer containing the above-mentioned crosslinked resin and, if necessary, a protective layer containing the crosslinked resin. However, in order to improve the characteristics as a recording medium, an adhesive layer, an intermediate layer, an undercoat layer, a back coat layer, and the like can be provided. Further, a magnetic recording layer may be provided. Further, each of the above-mentioned layers and the support may be colored with a coloring agent. That is, the recording medium may be partially or entirely colored by, for example, printing. Further, a colorless or light-colored print protection layer containing a resin as a main component may be provided on the colored print layer provided on the medium surface.

Examples of the resin used for the protective layer include polyvinyl alcohol, styrene-maleic anhydride copolymer, carboxy-modified polyethylene, melamine-formaldehyde resin, urea-formaldehyde resin and the like in addition to the above-mentioned crosslinked resin. The thickness of the protective layer is 0.1
The range is preferably from 20 to 20 μm, more preferably from 0.3 to
10 μm. It is also preferable to provide an intermediate layer between the recording layer and the protective layer for the purpose of improving the adhesion between the recording layer and the protective layer, preventing deterioration of the recording layer due to application of the protective layer, and preventing migration of additives in the protective layer to the recording layer. .

Further, a heat insulating undercoat layer can be provided between the support and the recording layer in order to effectively utilize the applied heat. The heat insulating layer can be formed by applying organic or inorganic fine hollow particles using a binder resin. An undercoat layer may be provided for the purpose of improving the adhesion between the support and the recording layer and preventing the penetration of the recording layer material into the support. The same resin as the above-mentioned resin for the recording layer can be used for the intermediate layer and the undercoat layer.

A filler may be added to the undercoat layer, the recording layer, the intermediate layer, and the protective layer. The filler can be divided into an inorganic filler and an organic filler. Examples of the inorganic filler include carbonates such as calcium carbonate and magnesium carbonate; silicates such as silicic anhydride, hydrous silicic acid, hydrous aluminum silicate, and hydrous calcium silicate;
Hydroxides such as alumina and iron oxide; zinc oxide, indium oxide, alumina, silica, zirconia oxide, tin oxide, cerium oxide, iron oxide, antimony oxide, barium oxide, calcium oxide, barium oxide, bismuth oxide,
Metal oxides such as nickel oxide, magnesium oxide, chromium oxide, manganese oxide, tantalum oxide, niobium oxide, thorium oxide, hafnium oxide, molybdenum oxide, iron ferrite, nickel ferrite, cobalt ferrite, barium titanate, potassium titanate; Zinc sulfide,
Metal sulfides such as barium sulfate or sulfate compounds;
Metal carbides such as titanium carbide, silicon carbide, molybdenum carbide, tungsten carbide, tantalum carbide; aluminum nitride, silicon nitride,
Examples include metal nitrides such as boron nitride, zirconium nitride, vanadium nitride, titanium nitride, niobium nitride, and gallium nitride. Organic fillers include silicone resin, cellulose resin, epoxy resin, nylon resin, phenolic resin, polyurethane resin, urea resin,
Melamine resin, polyester resin, polycarbonate resin, styrene resin such as styrene, polystyrene, polystyrene / isoprene, styrene vinylbenzene, acrylic resin such as vinylidene chloride acrylic, acrylic urethane, ethylene acrylic, polyethylene resin, benzoguanamine formaldehyde, melamine formaldehyde, etc. Formaldehyde resin, polymethyl methacrylate resin, vinyl chloride resin and the like. In the present invention, the organic filler may be used alone, but may be contained in two or more types, or may be a composite particle. Examples of the shape include a spherical shape, a granular shape, a plate shape, and a needle shape.

The content of the filler in the layer is 1 to 95% by volume, more preferably 5 to 75%.

A lubricant may be added to the undercoat layer, the recording layer, the intermediate layer, and the protective layer. Specific examples of the lubricant include synthetic waxes such as ester wax, paraffin wax and polyethylene wax: hardened castor oil and the like. Vegetable waxes: animal waxes such as hardened tallow oil:
Higher alcohols such as stearyl alcohol and behenyl alcohol: higher fatty acids such as margaric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenin chain, and furomenic acid: higher fatty acid esters such as sorbitan fatty acid esters: stearamide And amides such as oleic acid amide, lauric acid amide, ethylenebisstearic acid amide, methylenebisstearic acid amide, and methylolstearic acid amide.

The content of the lubricant in the layer is from 0.1 to 0.1 in volume fraction.
It is 95%, more preferably 1 to 75%. Further, an inorganic or organic ultraviolet absorber may be contained in the intermediate layer and the protective layer together with the resin (binder), and the content is preferably in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight of the binder.

As the organic ultraviolet absorber, 2- (2′-
(Hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-
3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-
5′-methylphenyl) benzotriazole, 2-
(2'-hydroxy-5'-octoxyphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'
-Di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-t-butyl-
Benzotriazole-based ultraviolet absorbers such as 5′-methylphenyl) -5-chlorobenzotriazole and 2- (2′-hydroxy-5′-ethoxyphenyl) benzotriazole;

2,4-dihydroxybenzophenone, 2
-Hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2 ′
-Dihydroxy-4-methoxybenzophenone, 2,
2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-oxybenzylbenzophenone , 2-hydroxy-4-chlorobenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, sodium 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2,2 ′
Benzophenone-based ultraviolet absorbers such as -dihydroxy-4,4'-dimethoxybenzophenone-sodium sulfonate;

Salicylate-based ultraviolet absorbers such as phenyl salicylate, p-octylphenyl salicylate, pt-butylphenyl salicylate, carboxyphenyl salicylate, methylphenyl salicylate, dodecylphenyl salicylate, 2-ethylhexylphenyl salicylate, homomenthylphenyl salicylate, etc. ,

2-ethylhexyl-2-cyano-3,
3'-diphenyl acrylate, ethyl-2-cyano-
Cyanoacrylate ultraviolet absorbers such as 3,3'-diphenylacrylate; p-aminobenzoic acid, glyceryl p-aminobenzoate, amyl p-dimethylaminobenzoate, and p- such as ethyl p-dihydroxypropylbenzoate.
Aminobenzoic acid-based ultraviolet absorbers; cinnamic acid-based ultraviolet absorbers such as p-methoxycinnamic acid-2-ethylhexyl and p-methoxycinnamic acid-2-ethoxyethyl; 4-t-butyl-4'-methoxy -Dibenzoylmethane, urocanic acid, ethyl urocanate and the like.

Solvents used for coating liquids for the intermediate layer and the protective layer,
Known methods used for the recording layer can be used for the coating liquid dispersing apparatus, coating method, drying / curing method, and the like.

In order to form a color image using the reversible thermosensitive recording medium of the present invention, the color image may be heated once to a color development temperature and then rapidly cooled. In particular,
For example, if the recording layer is heated for a short time with a thermal head or laser light, the recording layer is locally heated, so that the heat is immediately diffused and rapid cooling occurs, so that the coloring state can be fixed. On the other hand, in order to erase the color, heating may be performed by using an appropriate heat source for a relatively long time to cool, or heating may be temporarily performed to a temperature slightly lower than the coloring temperature. If the recording medium is heated for a long time, the temperature of a wide area of the recording medium rises, and the subsequent cooling is slowed down. As a heating method in this case, a heat roller, a heat stamp, hot air, or the like may be used, or heating may be performed for a long time using a thermal head. In order to heat the recording layer to the decoloring temperature range, the applied energy may be slightly reduced from that at the time of recording, for example, by adjusting the applied voltage and the pulse width to the thermal head. With this method, recording and erasing can be performed only with the thermal head, and so-called overwriting can be performed. Of course, it can be erased by heating to a decoloring temperature range by a heat roller or a heat stamp.

The reversible thermosensitive recording medium of the present invention is formed by holding the recording layer on the support exemplified above.
The support used at this time may have a thickness as required, and may be used alone or by laminating. That is, a support having an arbitrary thickness from about several μm to about several mm is used. Further, these supports may have a magnetic recording layer on the same side and / or the opposite side as the reversible thermosensitive recording layer. The reversible thermosensitive recording medium of the present invention may be attached to another medium via an adhesive layer or the like. The reversible thermosensitive recording medium of the present invention may be processed into a sheet shape or a card shape, the shape can be processed into any shape, and the surface of the medium can be printed. The reversible thermosensitive recording medium of the present invention may use an irreversible thermosensitive recording layer in combination. At this time, the color tone of each recording layer may be the same or different.

[0133]

The present invention will be described in more detail with reference to the following examples. In the examples, “parts” and “%” are based on weight. Example 1 Preparation of Recording Layer 1) 2-anilino-3-methyl-6-dibutylaminofluorane 2 parts 2) Developer having the following structure 8 parts

[0134]

Embedded image 3) 4 parts of a coloring / decoloring control agent having the following structure

[0135]

Embedded image CH ₃ (CH ₂ ) ₁₇ —NHCONH— (CH ₂ ) ₂ —COOH 4) 4 parts of a decolorization accelerator having the following structure

[0136]

Embedded image 5) 150 parts of a 15% tetrahydrofuran (THF) solution of phenoxy resin (PKHH manufactured by Union Carbide Co.) The average particle diameter of the above composition was 0.1 to 3 μm using a ball mill.
m. To the resulting dispersion, 20 parts of Coronate HL (a 75% solution of adduct-type hexamethylene diisocyanate in ethyl acetate) manufactured by Nippon Polyurethane Co., Ltd. was added.
The mixture was stirred well to prepare a recording layer coating solution. The recording layer coating solution having the above composition was applied onto a 188 μm-thick polyester film using a wire bar, dried at 100 ° C. for 2 minutes, and then dried at 60 ° C. for 24 hours to obtain a film thickness of about 8.0 μm. Was provided.

Preparation of protective layer 1) Urethane acrylate-based UV-curable resin 15 parts (C7-157, manufactured by Dainippon Ink and Chemicals) 2) Ethyl acetate 85 parts The above composition was thoroughly dissolved and stirred, and a protective layer coating solution was applied. Was prepared. The protective layer coating solution having the above composition was coated on the recording layer using a wire bar, dried at 90 ° C. for 1 minute, and then transferred under an ultraviolet lamp having an irradiation energy of 80 W / cm at a transport speed of 9 m / min. The protective layer having a thickness of 3 μm was provided by curing the recording medium to form a reversible thermosensitive recording medium of the present invention.

Example 2 Preparation of Recording Layer 1) 2-anilino-3-methyl-6-N-ethyl-Np-tolylaminofluoran 2 parts 2) Developer having the following structure 8 parts

[0139]

Embedded image 3) 4 parts of a coloring / decoloring control agent having the following structure

[0140]

Embedded image CH ₃ (CH ₂ ) ₁₇ —NHCONH— (CH ₂ ) ₅ —COOH 4) 4 parts of a decolorization accelerator having the following structure

[0141]

Embedded image 5) 150 parts of a 15% solution of acrylic polyol resin in tetrahydrofuran (THF) 150 parts of the above composition was averaged in a ball mill using a ball mill of 0.1 to 3 μm.
m. To the resulting dispersion, 20 parts of Coronate HL (a 75% solution of adduct-type hexamethylene diisocyanate in ethyl acetate) manufactured by Nippon Polyurethane Co., Ltd. was added.
The mixture was stirred well to prepare a recording layer coating solution. A recording layer was prepared in the same manner as in Example 1 using the recording layer coating solution having the above composition.

Preparation of protective layer 1) 15 parts of phenoxy resin (PKHH manufactured by Union Carbide) 2) 85 parts of tetrahydrofuran (THF) The above composition was pulverized and dispersed using a ball mill for 8 hours.
Coronate HL manufactured by Nippon Polyurethane Co., Ltd.
(75% of adduct type hexamethylene diisocyanate
(Ethyl acetate solution) (15 parts) was added and stirred well to prepare a protective layer coating solution. A protective layer coating solution having the above composition was applied on the recording layer using a wire bar, dried at 100 ° C. for 2 minutes, and then heated at 60 ° C. for 24 hours to form a protective layer having a thickness of about 3 μm. The reversible thermosensitive recording medium of the present invention was produced.

Example 3 Preparation of Recording Layer 1) 3- (4-Diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide 2 parts 2) 8 parts of the following developer

[0144]

Embedded image 3) 4 parts of a coloring / decoloring control agent having the following structure

[0145]

Embedded image CH ₃ (CH ₂ ) ₁₇ —NHCONH— (CH ₂ ) ₁₇ CH ₃ 4) 4 parts of decolorization accelerator having the following structure

[0146]

Embedded image 5) 150 parts of a 15% solution of acrylic polyol resin in tetrahydrofuran (THF) 150 parts of the above composition was averaged in a ball mill using a ball mill of 0.1 to 3 μm.
m. To the resulting dispersion, 20 parts of Coronate HL (a 75% solution of adduct-type hexamethylene diisocyanate in ethyl acetate) manufactured by Nippon Polyurethane Co., Ltd. was added.
The mixture was stirred well to prepare a recording layer coating solution. A recording layer was prepared in the same manner as in Example 1 using the recording layer coating solution having the above composition. -Preparation of protective layer 1) Acrylic polyol resin 15 parts 2) Methyl ethyl ketone (MEK) 85 parts A protective layer coating solution having the above composition was prepared in the same manner as in Example 2 to prepare a protective layer.

Example 4 Preparation of Recording Layer 1) 3,3'-bis (2-ethoxy-4-diethylaminophenyl) -4-azaphthalide 2 parts 2) Developer having the following structure 8 parts

[0148]

Embedded image 3) 4 parts of a coloring / decoloring control agent having the following structure

[0149]

Embedded image CH ₃ (CH ₂ ) ₁₇ —NHCONH— (CH ₂ ) ₁₀ CH ₃ 4) 4 parts of decolorization accelerator having the following structure

[0150]

Embedded image 5) 150 parts of a 15% tetrahydrofuran (THF) solution of a phenoxy resin (PKHH manufactured by Union Carbide Co.) The average particle diameter of the above composition was 0.1 to 3 μm using a ball mill.
m. To the resulting dispersion, 20 parts of Coronate HL (a 75% solution of adduct-type hexamethylene diisocyanate in ethyl acetate) manufactured by Nippon Polyurethane Co., Ltd. was added.
The mixture was stirred well to prepare a recording layer coating solution. A recording layer was prepared in the same manner as in Example 1 using the recording layer coating solution having the above composition. -Preparation of protective layer A protective layer was prepared in the same manner as in Example 1.

Comparative Example 1 The recording layer in Example 1 was removed from the coloring and decoloring control agent and the decolorizing accelerator, and the resin of the protective layer was made of vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide Co.). A reversible thermosensitive recording medium was produced in the same manner as in Example 1, except that the protective layer was produced by drying in a bath.

Comparative Example 2 The resin for the recording layer and the protective layer was replaced with a vinyl chloride-vinyl acetate copolymer (VYHH manufactured by Union Carbide Co.) except that the coloring and decoloring control agent and the decoloring accelerator were removed from the recording layer in Example 2. Example 2 except that the addition of coronate HL (crosslinking agent) was eliminated and the recording layer and the protective layer were prepared by drying in a thermostat.
In the same manner as in the above, a reversible thermosensitive recording medium was produced.

Comparative Example 3 A reversible thermosensitive recording medium was produced in the same manner as in Example 3 except that the decolorizing accelerator was omitted from the recording layer in Example 3.

Coloring Density Test The produced recording medium was printed with a thermal printing apparatus manufactured by Okura Electric Co., Ltd. at a voltage of 13.3 V and a pulse width of 1.2 msec, and the obtained image was measured with a Macbeth densitometer RD-914.

Remaining erase density test The color image obtained in the color density test was erased with a thermal gradient tester manufactured by Toyo Seiki Co., Ltd. at 110 ° C. for 1 second, and the density and background of the image portion after the erase were erased. The partial density was measured in the same manner as in the color density test. Next, the remaining density was calculated from the following equation. High-speed erasability can be evaluated from the remaining erase density. Remaining erase density = (density of image area after erasure)-(background density)

Storage characteristic test The densities of the image portion and the background portion obtained by the color development density test are measured, and they are defined as the image density before the test and the background density before the test, respectively.
This sample is stored under a drying condition of 50 ° C. for 24 hours, and the densities of the image portion and the background portion are measured in the same manner, and the image density is determined as the post-test image density and the post-test image background density, respectively. Next, the density retention rate is calculated from the following equation.

[0157]

(Equation 1)

Durability test Printing under the conditions of the color density test and erasing under the conditions of the remaining erase density test were repeated 50 times, and the state of the image density and the state of the recording medium surface were visually observed and evaluated according to the following ranks. . Rank 1: The image portion was in a good color development state, and no dent was observed. Rank 2: There is no image portion, but slight dents were observed. Rank 3: The coloring of the image area was uneven, and dents were also formed. Rank 4: The coloring state of the image area was extremely poor, and severe dents occurred. The results are shown in Table 20.

[0159]

[Table 20]

[0160]

As is apparent from the detailed and concrete description, the reversible thermosensitive recording medium of the present invention is excellent in high-speed erasability, and furthermore has good color developability, storability and printability even when used repeatedly. There is no scar and excellent durability.

[Brief description of the drawings]

FIG. 1 is a diagram showing color development / decoloration characteristics of a reversible thermosensitive recording medium of the present invention.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Fumio Kawamura 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2C065 AB01 AD07 AE01 AF01 DZ09 DZ12 2H026 AA07 AA09 BB02 BB25 CC10 DD43 DD45 DD48 DD53 DD55 FF25

Claims (14)

[Claims] 1. A reversible heat-sensitive material capable of forming a relatively colored state by using an electron-donating color-forming compound and an electron-accepting compound on a support and changing the heating temperature and / or the cooling rate after heating. In a reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing a composition, a secondary represented by the following formula (1), (2) or (3) as a decolorizing accelerator in the reversible thermosensitive recording layer. A reversible thermosensitive recording medium comprising a compound having two or more amide groups. Embedded image Embedded image Embedded image In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ represent a saturated or unsaturated hydrocarbon group which may have a substituent, and R ₁ and R ₂
May form a ring, and the formed ring may be via a nitrogen atom or an oxygen atom. 2. The reversible thermosensitive recording medium according to claim 1, wherein the decolorization accelerator uses at least one of the compounds represented by the following formulas (4), (5) and (6). Embedded image Embedded image Embedded image Wherein R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ ,
R ₁₄ , R ₁₅ , R ₁₆ , R ₁₇ and R ₁₈ represent a saturated or unsaturated hydrocarbon group which may have a substituent, and R ₇ and R ₈ and R ₉ and R ₁₀ form a ring. And the formed ring may be via a nitrogen atom or an oxygen atom. 3. The reversible thermosensitive recording medium according to claim 1, wherein a coloring / erasing control agent is used in the reversible thermosensitive recording layer. 4. The compound according to claim 1, wherein a compound having a divalent group containing a hetero atom and an alkyl chain having 6 or more carbon atoms is used as the coloring / decoloring controlling agent.
4. The reversible thermosensitive recording medium according to item 1. 5. The reversible thermosensitive recording medium according to claim 1, wherein a phenol compound having an alkyl chain having 6 or more carbon atoms is used as the electron accepting compound. 6. The reversible thermosensitive recording medium according to claim 1, wherein the reversible thermosensitive recording layer contains a crosslinked resin. 7. The reversible thermosensitive recording medium according to claim 1, wherein the crosslinked resin is crosslinked by an isocyanate compound. 8. The recording layer according to claim 1, wherein a layer containing an inorganic or organic ultraviolet absorber is provided on the recording layer.
The reversible thermosensitive recording medium according to any one of the above. 9. The reversible thermosensitive recording medium according to claim 1, wherein a layer using a crosslinked resin is provided as a protective layer on the recording layer. 10. The reversible thermosensitive recording medium according to claim 1, further comprising a magnetic recording layer. 11. The reversible thermosensitive recording medium according to claim 1, wherein the medium is processed into a card shape or a sheet shape. 12. The printing apparatus according to claim 1, wherein at least a part of the front surface and / or the back surface has a printed portion.
2. The reversible thermosensitive recording medium according to any one of 1. 13. The method for erasing an image on a reversible thermosensitive recording medium according to claim 1, wherein the color is erased by heating to a temperature lower than the color development start temperature. 14. An image erasing apparatus according to claim 13, wherein the heating portion for erasing the image is a heater selected from a ceramic heater, a sheet heater, and a heat roller. .