JP2000103171A - Reversible thermal recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance high speed erasing characteristics, a coloring property, and preservation characteristics by the use of a compound having a secondary amide group expressed by specific formulas as a decoloring accelerator, and an alkyl chain of a specific carbon atom or more in a reversible thermal recording layer. SOLUTION: A compound of a structure having a secondary amide group expressed by formulas of I, II, III as a decoloring accelerator, and a 6C or more alkyl chain is used in a reversible thermal recording layer. In the formula, R1 R2, R3, R4 and R5 each show a saturated or unsaturated hydrocarbon group that can include a substitutional group, and R1 and R2 can form a ring; of which the ring can be formed via a nitrogen atom, an oxygen atom, or a sulfur atom. The recording medium is provided with a composition consisting of a coloring agent and developing agent, and a ratio between them is made roughly 0.1-20 parts of a developing agent to one of coloring agent at a mol ratio. The support body employs paper, resin, a film, synthetic paper, metallic foil, glass, and the like.

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. JP-A-1936991, JP-A-61-237684 using a compound such as phenolphthalein or thymolphthalein as a developer, and a recording layer containing a homogeneous compatibilizer of a color former, a developer and a carboxylic acid ester. JP-A-62-138556, JP-A-62-138568 and JP-A-62-1408.
No. 81, Japanese Unexamined Patent Publication No. 63-173684 using ascorbic acid dielectric as a developer, Japanese Unexamined Patent Publication (Kokai) No. 2 using bis (hydroxyphenyl) acetic acid or a salt of gallic acid and a higher aliphatic amine as a developer. JP-A-188293 and JP-A-2-188294 are 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).

Further, Japanese Patent Application Laid-Open Nos. Hei 7-52542, Hei 7-68933, Hei 8-132735, Hei 8-310128, Hei 9-272
262, JP-A-9-270563, JP-A-9-300817, and JP-A-9-300820 propose a high-speed erasing property by adding a specific decolorization accelerator. There are problems such as insufficient erasability and poor image storability.

Further, if printing and erasing are repeatedly performed under actual use conditions, problems such as a decrease in image density and bleeding (deformation of a printed portion) 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.

To cope with such a problem of the recording medium, Japanese Patent Application Laid-Open No. 6-340171 proposes improvement of the repetition durability by adding particles having an average particle diameter of 1.1 times or more of the recording layer thickness. Japanese Patent Application Laid-Open No. 8-156410 proposes to improve the head durability by providing a protective layer for the glossiness and the surface roughness of the characteristics to improve the 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. 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.

[0009]

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.

[0010]

Means for Solving the Problems The present inventors have found that high-speed erasing characteristics can be obtained by using a decolorizing accelerator having a structure having a second amide group and an alkyl chain having 6 or more carbon atoms. . That is, the reversible thermosensitive recording medium of the present invention uses an electron-donating color-forming compound and an electron-accepting compound on a support, and relatively develops a color due to 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 reversible thermochromic composition capable of forming a decolored state and a decolored state, a second amide is contained in the reversible thermosensitive recording layer as a decolorizing accelerator. By using a compound having a structure having a group and an alkyl chain having 6 or more carbon atoms, high-speed erasing characteristics are excellent. In this case, examples of the second amide group include groups represented by the following formulas (1) to (3).

[0011]

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[0012]

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[0013]

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, the formed ring is a nitrogen atom,
It may be via an oxygen atom or a sulfur atom. Further R
Examples of the hydrocarbon group which may have a substituent and is preferably used for ₁ , R ₂ , R ₃ , R ₄ and R ₅ include a straight-chain or branched group, -O-, -S -, -CO-, -CO
It may be via an O-group. Further, it may have an aromatic ring or an aliphatic ring. Further, these groups may be substituted with a hydroxyl group, a halogen atom or the like. Table 1 shows R ₁ , R ₂ ,
Preferred structures of R ₃ , R ₄ and R ₅ are shown below.
n, n ′, n ″, n ″ ″, n ″ ″ represent an integer of 0 to 22.

[0014]

[Table 1] When R ₁ and R ₂ form a cyclic structure, the structures shown in Table 2 are preferably used.

[0015]

[Table 2] The above groups may be further substituted by a hydroxyl group or a halogen atom.

Preferred examples of the decoloring accelerator used in the present invention are shown in Table 3 below. However, the decolorization accelerator compound used in the present invention is not limited to these.

[0017]

[Table 3] n, n ′, n ″, n ″ ″, and n ″ ″ represent an integer of 0 to 21. However, not all are less than 5.

Further, the decoloring accelerator used in the present invention includes:
Having an associative group results in excellent image storability. Examples of the associative group used in the present invention include the groups in Table 4.

[0019]

[Table 4]

The associative group may have at least one of the above groups. Examples of the associative group preferably used in the decolorization accelerator used in the present invention are as shown in Table 5. Is mentioned.

[0021]

[Table 5] Examples of the discoloration accelerator having these associative groups include those shown in Table 6. X represents the above associative group,
n, n ′, n ″, n ″ ″ represent an integer of 0 to 21,
Not all are less than 5.

Table 6 shows preferred examples of the decolorizing accelerator used in the present invention. However, the decoloring accelerator used in the present invention is not limited to these compounds.

[0023]

[Table 6]

Further, by having two or more associative groups, a reversible thermosensitive recording medium having further improved image stability can be obtained. As an example, the following formula (7) in Table 6 is used.
In the case of the structure of (1), a structure represented by the formula (8) can be given.
Similarly, in the case of other structures in Table 6, there is a structure having two or more associative groups.

[0025]

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[0026]

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In this case, X ′ represents an associative group as in the case of X, and n ″ ″ represents 0 to 22 as in the above. p is 1
X ′ represents an integer of 4 to 4, and is repeated when m is 2 or more.
And n ′ ″ ″ may be the same or different. Table 7 shows specific examples of the decoloring accelerator represented by formulas (7) and (8), but the present invention is not limited to these compounds. Similar specific examples are also given for the compounds having the structures shown in Tables 3 and 6.

[0028]

[Table 7-1]

[0029]

[Table 7-2]

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 and decoloring controlling agent, the coloring and decoloring characteristics can be further improved.

Further, by using a compound represented by the following general formula (9) 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 a structure represented by the following formula.

[0032]

Embedded image In the formula, X ₁ , X ₂ and X ₃ represent a group containing a hetero atom,
R ₆ , R ₇ and R ₈ represent a group having 1 to 22 carbon atoms. R, s, and k each independently represent 0 or 1, and t represents an integer of 0 to 4. Where r, s, t
And k cannot be 0 at the same time. Further, R ₈ and X ₂ repeated when t is 2 or more may be the same or different. R ₆ , R ₇ , R ₈ and R ₉ may contain a heterocyclic ring. More preferably, the sum of the carbon numbers of R ₆ , R ₇ and R ₈ is 8 or more. R ₆ , R ₇ and R ₈ each represent a hydrocarbon group which may have a substituent, and may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group; It may be a hydrogen group.
Further, the aliphatic hydrocarbon group may be linear or branched,
It may have an unsaturated bond. Examples of the substituent attached to the hydrocarbon group include a hydroxyl group, a halogen, and an alkoxy group. If the sum of the number of carbon atoms of R ₆ , R ₇ , R ₈ and R ₉ is 7 or less, the stability of color development and the decoloring property decrease, so that the number of carbon atoms is 8
The above is preferred, and more preferably 11 or more.
Preferred examples of R ₆ and R ₈ include those shown in Table 8.

[0033]

[Table 8]

Preferred examples of R ₇ , R ₈ and R ₉ include those shown in Table 9.

[0035]

[Table 9] In the formula, q, q ', q ", and q"' are respectively R ₇ ,
Represents an integer satisfying the carbon number of R ₈ and R ₉ .

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 10.

[0037]

[Table 10]

Examples thereof are shown in Table 11.

[0039]

[Table 11]

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 12.

[0041]

[Table 12]

Examples are shown in Table 13.

[0043]

[Table 13]

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

[0045]

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[0046]

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[0047]

Embedded image R ₆ , R ₇ , R ₈ , R ₉ , X ₁ , X ₂ and X ₃ each represent the same groups as described above. In addition, t is an integer of 0 to 4, and R ₈ and X ₂ repeated when t is 2 or more may be the same or different. Further, s is 0
Alternatively, 1 is indicated. However, t and s are not simultaneously 0. Further, particularly preferred structures include the following.

[0048]

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[0049]

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[0050]

Embedded image

[0051]

Embedded image

[0052]

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[0053]

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Specific examples of the coloring and decoloring control agents used in the present invention include, for example, those of the formula (17) shown in Table 14.
The compound of. In addition, the same compounds can be mentioned for the formula (18).

[0055]

[Table 14]

As a more specific example, for example,

[0057]

Embedded image and

[0058]

Embedded image Examples of the compound represented by are the compounds shown in Table 15.

[0059]

[Table 15]

Further, the deterioration due to repeated use of the recording medium, that is, the destruction of the coating film due to a large number of printing / erasing operations is greatest in the recording layer, and the heat resistance of the recording layer is improved, so that the durability of the recording medium is reduced. Found to improve. 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 resin in a cross-linked state is, for example, a combination of a cross-linking agent and a resin having an active group which reacts with the cross-linking agent, and is 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, Vinyl chloride
Examples thereof include a vinyl acetate-maleic anhydride copolymer.

Examples of the crosslinking agent for thermal crosslinking include isocyanates, amino resins, phenolic 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 ultraviolet light 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-added acrylate, trisacryloyloxyethyl phosphate, pentaerythritol acrylate, triacrylate of 3 moles of propylene oxide adduct 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.

In the case of crosslinking 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.

As the light source for the ultraviolet irradiation used in the present invention, there are a mercury lamp, a metal halide lamp, a gallium lamp, a mercury xenon lamp, a flash lamp, etc., and the ultraviolet absorption wavelength of the above-mentioned photopolymerization initiator and photopolymerization accelerator. 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, according to the present invention, the use of a phenolic compound represented by the following formula as a color developer provides a good image contrast.

[0071]

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
₁₀ represents a divalent hydrocarbon group, and R ₁₁ represents a group having 1 to 2 carbon atoms.
2 represents a hydrocarbon group. V represents an integer of 0 to 4, and R ₁₀ and X ₅ repeated when v is 2 to 4
May be the same or different. U is 1 to 3
Represents

Specifically, R ₁₀ and R ₁₁ each represent a hydrocarbon group which may have a substituent, and these 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 ₁₀
May be a direct bond. When the sum of the carbon numbers of R ₁₀ and R ₁₁ 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 ₁₀ include those shown in Table 16 in addition to the direct bond.

[0073]

[Table 16] Preferred examples of R ₁₁ include those in Table 17.

[0074]

[Table 17]

In the formula, q, q ', q ", q"' each represent an integer satisfying the carbon number of R ₁₀ and R ₁₁ . 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 18.

[0076]

[Table 18] Examples thereof include those shown in Table 19.

[0077]

[Table 19]

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

[0079]

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[0080]

Embedded image

[0081]

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[0082]

Embedded image

[0083]

Embedded image

[0084]

Embedded image

[0085]

Embedded image

[0086]

Embedded image W in the formula, w ', y is an integer satisfying the number of carbon atoms of R ₁₀ or R ₁₁ independently.

As more specific examples of the phenol compound in the present invention, for example, the compounds shown in Table 20 below as examples of the formula (23) can be mentioned. In addition, other compounds represented by the formulas (22) and (24) to (29) are also similar to these compounds as specific examples. However, the present invention is not limited to these.

[0088]

[Table 20-1]

[0089]

[Table 20-2]

[0090]

[Table 20-3]

Further, more specific phenol compounds include, for example, the following. Table 21 shows specific examples of the compound represented by the following formula (30) in Table 20. The same applies to the compounds represented by other formulas in Table 20. However, the present invention is not limited to these.

[0092]

Embedded image

[0093]

[Table 21]

Further, according to the present invention, a protective layer using a crosslinked resin may be provided on the recording layer, and the crosslinked resin may be the above-mentioned thermosetting resin, ultraviolet curing resin, or the like. 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.

As the aliphatic carboxylic compound, the following compounds can be exemplified. 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 used arbitrarily, and the following compounds are particularly preferably used alone or in combination.

[0100]

Embedded image (In the formula, R ₁₂ and R ₁₃ represent a lower alkyl group, an aryl group which may be substituted, or a hydrogen atom, and R ₁₂ and R ₁₃ may be bonded to each other to form a ring. R ₁₄ is a lower alkyl group, a halogen atom or a hydrogen atom, also, R ₁₅
Is a lower alkyl, a halogen atom, a hydrogen atom or a formula (3
It represents a substituted anilino group represented by 2). )

[0101]

Embedded image (Wherein, R ₁₆ represents a lower alkyl group or a hydrogen atom,
Y represents a lower alkyl group or a halogen atom. Z is 0
Represents an integer from to 3. )

[0102]

Embedded image (In the formula, R ₁₇ to R ₂₀ represent an alkyl group or a hydrogen atom, and R ₂₁ represents an alkyl group, an alkoxy group, or a hydrogen atom.)

[0103]

Embedded image (In the formula, R ₂₂ to R ₂₅ represent a lower alkyl group or a hydrogen atom. R ₂₆ and R ₂₇ 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 where they can react with each other in a molecule. 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 ratio of the color former to the color developer varies in an appropriate range depending on the combination of the compounds used, but the color developer is generally in the range of 0.1 to 20 with respect to the color developer 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 by 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.

There is no particular limitation on the coating method for forming the recording layer. 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. In this case, a part or the whole surface of the recording medium may be colored, for example, by 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.

Examples of the resin used for the protective layer include polyvinyl alcohol, styrene-maleic anhydride copolymer, carboxy-modified polyethylene, melamine-formaldehyde resin, and urea-formaldehyde resin 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 by volume.
It is 95%, more preferably 1 to 75%. The intermediate layer and the protective layer may contain an inorganic or organic ultraviolet absorber, and the content is preferably in the range of 0.5 to 10 parts by weight based on 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 ester 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.

[0138]

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 1) 2 parts of 2-anilino-3-methyl-6-dibutylaminofluoran 2) 8 parts of a developer having the following structure

[0139]

Embedded image 3) Decolorization accelerator having the following structure: 3 parts

[0140]

Embedded image 4) 70% of 15% tetrahydrofuran (THF) solution of acrylic polyol resin

The above composition was pulverized and dispersed using a ball mill to an average particle size of 0.1 to 3 μm. The resulting dispersion was treated with Coronate HL (Adduct-type hexamethylene diisocyanate 75% ethyl acetate solution) manufactured by Nippon Polyurethane Co., Ltd.
0 parts were added and 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 heated at 60 ° C. for 24 hours to obtain a film thickness of about 8.0.
A recording layer having a thickness of μm was provided, and a reversible thermosensitive recording medium of the present invention was produced.

Example 2 A reversible thermosensitive recording medium was produced in the same manner as in Example 1, except that the following decolorization accelerator was used in place of the decolorization accelerator in Example 1.

[0143]

Embedded image

Example 3 A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that the following developer and decolorizer were used in place of the developer and decolorizer in Example 1. Was prepared.

[0145]

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[0146]

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Example 4 A reversible thermosensitive recording medium was produced in the same manner as in Example 3, except that the following decolorization accelerator was used instead of the decolorization accelerator in Example 3.

[0148]

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Example 5 A reversible thermosensitive recording medium was produced in the same manner as in Example 3 except that the following decolorization accelerator was used instead of the decolorization accelerator in Example 3.

[0150]

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Example 6 Example 1 was repeated except that the dispersion of Example 1 was changed to the following composition.
A reversible thermosensitive recording medium was obtained in the same manner as described above. 1) 2-anilino-3-methyl-6-dibutylaminofluorane 2 parts 2) Color developer having the following structure 8 parts

[0152]

Embedded image 3) 1 part of decolorization accelerator having the following structure

[0153]

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

[0154]

Embedded image 5) 70% of 15% tetrahydrofuran (THF) solution of acrylic polyol resin

Example 7 A reversible thermosensitive recording medium was produced in the same manner as in Example 6, except that the following decolorization accelerator was used instead of the decolorization accelerator in Example 6.

[0156]

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Example 8 A reversible thermosensitive recording medium was produced in the same manner as in Example 6, except that the following decolorization accelerator was used instead of the decolorization accelerator in Example 6.

[0158]

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Example 9 A reversible thermosensitive recording medium was prepared in the same manner as in Example 6, except that the following decolorization accelerator was used in place of the decolorization accelerator in Example 6.

[0160]

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Example 10 A reversible thermosensitive recording medium was produced in the same manner as in Example 6, except that the following decolorization accelerator was used in place of the decolorization accelerator in Example 6.

[0162]

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Example 11 A reversible thermosensitive recording medium was produced in the same manner as in Example 6, except that the following decolorization accelerator was used instead of the decolorization accelerator in Example 6.

[0164]

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Example 12 A reversible thermosensitive recording medium was prepared in the same manner as in Example 6, except that the following decolorization accelerator was used in place of the decolorization accelerator in Example 6.

[0166]

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Example 13 A reversible thermosensitive recording medium was prepared in the same manner as in Example 6, except that the following decolorization accelerator was used instead of the decolorization accelerator in Example 6.

[0168]

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Example 14 A reversible thermosensitive recording medium was produced in the same manner as in Example 6, except that the following decolorization accelerator was used in place of the decolorization accelerator in Example 6.

[0170]

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Comparative Example 1 Example 1 was repeated except that the following color developing agent was used instead of the color developing agent and the color erasing accelerator in Example 1, and no color erasing accelerator was used.
In the same manner as in the above, a reversible thermosensitive recording medium was produced.

[0172]

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Comparative Example 2 A reversible thermosensitive recording medium was prepared in the same manner as in Example 1 except that the following decolorization accelerator was used instead of the decolorization accelerator in Example 1.

[0174]

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The reversible thermosensitive recording medium produced as described above was applied to 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. The color image was erased with a thermal gradient tester manufactured by Toyo Seiki Co., Ltd. under the conditions of 110 ° C. for 1 second, and the density of the image portion after the color was erased and the background density were measured. Next, the remaining density was calculated from the following equation.

## EQU1 ## Remaining erase density = (density of image portion after erasure)-
(Surface density)

Then, the densities of the obtained image portion and the background portion were measured, and the densities were measured as the image density before the test and the background density before the test, respectively. The sample was stored under a drying condition of 50 ° C. for 24 hours. The densities of the image portion and the background portion are measured, and the measured image density and the post-test background density are used, respectively. Next, the concentration retention was calculated from the following equation.

[0177]

(Equation 2) Table 22 shows the above results.

[0178]

[Table 22]

Example 15 A protective layer having the following composition was provided on the recording layer prepared in Example 10 to prepare a reversible thermosensitive recording medium. [Preparation of Protective Layer] 1) 15 parts of a urethane acrylate-based UV-curable resin (C7-157 manufactured by Dainippon Ink and Chemicals, Inc.) 2) 85 parts of ethyl acetate The above composition was thoroughly dissolved and stirred to prepare a protective layer coating solution. The protective layer coating solution having the above composition is coated on the recording layer using a wire bar, dried at 90 ° C. for 1 minute, and passed under an ultraviolet lamp having an irradiation energy of 80 W / cm at a transport speed of 9 m / min. Cured to provide a protective layer having a thickness of 3 μm,
A reversible thermosensitive recording medium of the present invention was produced.

Example 16 A protective layer having the following composition was provided on the recording layer prepared in Example 11 to prepare a reversible thermosensitive recording medium. [Preparation of Protective Layer] 1) 15 parts of a urethane acrylate-based UV-curable resin (C7-157 manufactured by Dainippon Ink and Chemicals, Inc.) 2) 85 parts of ethyl acetate The above composition was thoroughly dissolved and stirred to prepare a protective layer coating solution. The protective layer coating solution having the above composition is coated on the recording layer using a wire bar, dried at 90 ° C. for 1 minute, and passed under an ultraviolet lamp having an irradiation energy of 80 W / cm at a transport speed of 9 m / min. Cured to provide a protective layer having a thickness of 3 μm,
A reversible thermosensitive recording medium of the present invention was produced.

When the reversible thermosensitive recording medium produced as described above was repeated 50 times under the above-described color-forming conditions and decoloring conditions, the reversible thermosensitive recording media of Examples had no occurrence of dents and the like. The coloring and decoloring densities were maintained.

Comparative Example 3 In place of the acrylic polyol resin used in Example 10, 120 parts of a 15% MEK solution of polyvinyl chloride-vinyl acetate resin (VYHH manufactured by Union Carbide Co.) was used, and a recording layer was formed without using coronate HL. Then, instead of the protective layer used in Example 15, a MEK solution of polyvinyl chloride-vinyl acetate resin (VYHH manufactured by Union Carbide) was used, and dried at 100 ° C. for 3 minutes to provide a protective layer having a thickness of about 3 μm. Other than Example 15
In the same manner as in the above, a reversible thermosensitive recording medium was produced. When the reversible thermosensitive recording medium produced as described above was repeated 50 times under the above-described color forming conditions and decoloring conditions, the reversible thermosensitive recording media of the examples showed large, uniform image coloring and erasure such as occurrence of punching. Couldn't do it.

Example 17 On the recording layer prepared in Example 10, an intermediate layer having the following composition was provided. [Preparation of Intermediate Layer] 30 parts of 15% methyl ethyl ketone (MEK) solution of acrylic polyol resin Biosorb 130 (2-hydroxy-4-n-octoxy) benzophenone 4 parts manufactured by Kyodo Chemical Co. 4 parts of coronate HL 4 parts of the above liquid was used using a wire bar. And apply at 100 ℃
After drying for 60 minutes at 60 ° C for 24 hours,
m intermediate layers were provided. Next, a protective layer was provided in the same manner as in Example 15 to obtain a reversible thermosensitive recording medium of the present invention. After the reversible thermosensitive recording medium produced as described above is colored under the same coloring conditions as described above, it is irradiated with a fluorescent lamp at 5000lux for 100 hours, and then erased under the same erasing conditions as described above to examine deterioration by light. As a result, no change was observed in the image portion after light irradiation, and the image portion was in a good state without any erasure after erasure.

[0184]

As described above, the reversible thermosensitive recording medium of the present invention has excellent high-speed erasability, and further has excellent storage stability, durability and light resistance. is there.

[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 Tadafumi Tatewaki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Masafumi Torii 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Inside Ricoh Company (72) Inventor Fumio Kawamura 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Hiroaki Matsui 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company F Terms (reference) 2H026 AA07 AA09 BB02 BB25 CC10 DD43 DD45 DD46 DD48 DD53 DD55 FF11 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 class represented by the following formula (1), (2) or (3) as a decolorizing accelerator in the reversible thermosensitive recording layer. A reversible thermosensitive recording medium characterized by using a compound having an amide group and an alkyl chain having 6 or more carbon atoms. 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, the formed ring is a nitrogen atom,
It may be via an oxygen atom or a sulfur atom. 2. The reversible thermosensitive recording medium according to claim 1, wherein the decoloring accelerator has at least one associative group. 3. An associative group represented by the following formula (4) or (5):
The reversible thermosensitive recording medium according to claim 2, wherein the recording medium has one or more groups represented by the following formulae. Embedded image Embedded image Embedded image 4. The reversible thermosensitive recording medium according to claim 1, wherein the reversible thermosensitive recording layer contains a crosslinked resin. 5. The reversible thermosensitive recording medium according to claim 1, wherein a phenol compound having an alkyl chain having 8 or more carbon atoms is used as the electron accepting compound. 6. 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. 7. The reversible thermosensitive recording medium according to claim 1, wherein the crosslinked resin is crosslinked by an isocyanate compound. 8. The reversible thermosensitive recording medium according to claim 1, wherein a layer containing an inorganic or organic ultraviolet absorber is provided on the recording layer. 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 reversible thermosensitive recording medium according to claim 1, wherein a printing portion is provided on at least a part of the front surface and / or the back surface. 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. .