JP2003237229A - Reversible thermal recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reversible thermal recording material enabling stable and repeated formation and erasure of an image having a clear contrast, with high sensitivity and in many times of 1,000 times or more. <P>SOLUTION: The reversible thermal recording material contains a normally colorless or light-colored leuco dye, a reversible developer that develops the color of the leuco dye by heating and extinguishes the color thereof by reheating, and a photothermal conversion dyestuff. The rate of deterioration of the dyestuff by irradiation with a laser light having an oscillation wavelength of 830 nm is 20% or below. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermosensitive recording material whose color tone changes reversibly by controlling thermal energy.

[0002]

2. Description of the Related Art In recent years, reversible thermosensitive recording materials have been attracting attention because they can form temporary images and can erase the images when they are no longer needed. Typical examples thereof are Japanese Patent Laid-Open No. 6-210954 and Japanese Patent Laid-Open No. 6-210954.
No. 171225, JP-A-7-68933, JP-A-7-68934 and the like, which are usually colorless or light-colored leuco dye, and this leuco dye is colored by heating, and this is reheated. A reversible thermosensitive recording material using a reversible color developing agent for decoloring is known.

However, in such a conventional reversible thermosensitive recording material, when recording and erasing of an image by heating are repeated,
In particular, when a thermal head is used, the surface is rubbed while being heated, so that the surface of the recording layer is scratched, and if it becomes severe, a uniform image cannot be recorded. On the other hand, in JP-A-6-344673 and JP-A-8-156410, a protective layer is provided on the surface of such a reversible thermosensitive recording material to reduce scratches on the surface of the recording layer when a thermal head is used. Is proposed. However, if the conventional reversible thermosensitive recording material is provided with a protective layer, it may be difficult to say that the scratch resistance is sufficient when the number of recording and erasing increases. In addition, when recording and erasing are repeated by a method in which heat and pressure are applied to the reversible thermosensitive recording layer at the same time as in a thermal head, the reversible thermosensitive recording layer is subjected to temperature and pressure to elute the reversible thermochromic composition. However, there was a problem that the layer was destroyed and the recording density was lowered.

As a method for reducing the deterioration due to such a thermal head, Japanese Patent Laid-Open Nos. 57-82088 and 64-14077 disclose resin base materials such as vinyl chloride-vinyl acetate copolymer. In a reversible heat-sensitive recording material in which an organic low-molecular substance such as a higher fatty acid is dispersed, a method of incorporating carbon black or an infrared absorbing dye and recording with a laser beam is disclosed.
According to this method, non-contact printing is possible, but since the image is a so-called cloudy type formed by light scattering,
The contrast was low and the visibility was poor.

On the other hand, in JP-A-5-8537 and JP-A-11-151856, various photothermal conversion materials using a leuco dye and a reversible developer as a reversible thermosensitive recording material are disclosed. A system for recording with a near-infrared laser beam in combination with the above has been proposed. This system certainly gives a clear image contrast,
The formation and erasing of a highly sensitive image and the repeatability of 1000 times or more, which are important problems in practical use, have not been verified. In fact, according to an additional test by the present inventors, when a metal vapor deposition film such as Cr is used as a photothermal conversion material, it is not possible to selectively give a high absorbance in accordance with the wavelength of the near infrared laser light. Therefore, the recording sensitivity is low. In addition, JP-A-11-151
The layer structure disclosed in Japanese Patent No. 856 is not sufficient in terms of recording sensitivity. In the example of the publication, after the printing and the erasing are repeated 100 times, the recording surface is observed and there is no unevenness in the recording state and the erasing state. The above repeatability has not been verified or guaranteed at all. In the first place, the technology that uses a photothermal conversion dye to convert the energy of near-infrared laser light into heat for recording is the CD-R
Studies have been concentrated on write-once type recording materials such as those described above, and recordings for rewriting many times rely mainly on inorganic materials. Under the present circumstances, no technical guideline is given at all for enabling the photothermal conversion dye to be repeated a large number of times, such as 1000 times or more, by a near infrared laser beam.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to obtain an image having clear contrast with high sensitivity and 1000
An object of the present invention is to provide a reversible thermosensitive recording material which can be repeatedly formed and erased repeatedly over a number of times.

[0007]

Means for Solving the Problems As a result of studies to solve these problems, the present inventors have found that normally a colorless or light-colored leuco dye, which is colored by heating and then reheated to be erased. A reversible thermosensitive recording material containing a reversible developer and a photothermal conversion dye, wherein the deterioration rate of the dye upon irradiation with laser light having an oscillation wavelength of 830 nm is 20% or less. I found that the problem was solved.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, there is provided a reversible thermosensitive recording material capable of stably forming and erasing an image having a clear contrast with high sensitivity and over a large number of times of 1000 times or more. Provided.

A reversible heat-sensitive recording material which records and erases an image by repeating 1000 times or more with a near infrared laser beam using a photothermal conversion dye is required to have high heat resistance and laser light resistance. The present inventors have examined the heat resistance and laser light resistance characteristics of the constituent elements of the present recording material, and as a result, the laser light resistance characteristics of the photothermal conversion dye are the most important factors for recording and erasing many times. I found that. If the laser light resistance of the photothermal conversion dye is low, the dye deteriorates at a small number of repetitions, the efficiency of converting the laser light into heat decreases, and it becomes impossible to record or erase an image. Such properties of photothermal conversion dyes have never been measured previously. Light resistance to sunlight and fluorescent lamps involves the reaction of dyes in the excited state with triplet oxygen and the generation and reaction of singlet oxygen, so it is reasonable to use it as data to predict laser light resistance characteristics. Lack sex. Therefore, the present inventors have found that under the temperature condition of 25 ° C., 830
² J / cm ² with a laser having an oscillation wavelength of nm
The deterioration rate (hereinafter, simply referred to as the deterioration rate) when the above energy was repeatedly irradiated 1000 times was measured. As a result, it has been found that the deterioration rate varies depending on the type of the photothermal conversion dye, and the problem of the present invention can be solved by selecting a photothermal conversion dye having a deterioration rate of 20% or less.

Naturally, the lower the deterioration rate, the more advantageous it is. The deterioration rate is preferably 15% or less, more preferably 10% or less, further preferably 5% or less. When the deterioration rate exceeds 20%, as the recording and erasing are repeated, the color density is gradually lowered and the density of the erased portion is gradually increased, and the contrast is lowered. In order to make full use of such a photothermal conversion dye having a large deterioration rate, a countermeasure to add a large amount of dye in anticipation of deterioration is a problem such as coloring of the reversible thermosensitive recording material due to an increase in cost and an increase in absorption of the visible portion of the dye. In addition to the above points, there is a problem that the thermal energy used for recording and erasing becomes excessive in the initial state and the deterioration of the leuco dye and the binder is accelerated.

A specific method of measuring the deterioration rate includes preparation of a sample, measurement of absorbance, deterioration test, and calculation of deterioration rate. The details will be described below.

The sample used for measuring the deterioration rate is
A transparent support having no absorption in the near infrared region, such as a polyethylene terephthalate (PET) sheet, on which a film containing a photothermal conversion dye is formed is used. The film containing the photothermal conversion dye is formed by using as a binder a resin that does not absorb in the near infrared region and is stable against heat generated during measurement. The amount of the photothermal conversion dye is not limited as long as the absorbance can be measured, but it is preferably the same as the amount contained in the reversible thermosensitive recording material.

The absorbance is measured by the transmission method, and the absorbance at 830 nm is determined.

The laser used for the deterioration test has an oscillation wavelength of 8
A 30 nm semiconductor laser is used. The sample is placed under a temperature condition of 25 ° C. and repeatedly irradiated with laser light of ² J / cm ² 1000 times.

The deterioration rate is a value obtained by dividing the value obtained by subtracting the absorbance measured after the deterioration test from the absorbance measured before the deterioration test by the absorbance measured before the deterioration test by 100 times.

In the present invention, a preferable example of a near infrared laser used for recording and erasing an image is 740n.
a semiconductor laser having a light emitting region at m to 910 nm or 90
A YAG laser having an emission region of 0 nm to 1200 nm can be used, but the present invention is not limited thereto. Naturally, the photothermal conversion dye is selected so as to have a sufficient extinction coefficient at the wavelength of the light emitted from these light sources. In the present invention, recording of an image may be performed by using light from the above-mentioned light source, while erasing may be performed by using a heat roll or a heat stamp that causes less thermal or mechanical damage to the recording material.

Specific examples of the photothermal conversion dye used in the present invention include phthalocyanine compounds, metal complex compounds,
Examples thereof include polymethine compounds and naphthoquinone compounds, but are not limited thereto. Preferable photothermal conversion dyes include phthalocyanine compounds and metal complex compounds in terms of photothermal conversion efficiency, solubility in solvents, dispersibility in resins, and light resistance to ultraviolet light, and phthalocyanine compounds are particularly preferred.

Preferred examples of the phthalocyanine compound include naphthalocyanine compounds, metal-free phthalocyanine compounds, iron phthalocyanine compounds, copper phthalocyanine compounds, zinc phthalocyanine compounds, nickel phthalocyanine compounds, vanadyl phthalocyanine compounds, indium chloride phthalocyanine compounds, tin phthalocyanine compounds and the like. , And more preferably vanadyl phthalocyanine compounds, zinc phthalocyanine compounds, and tin phthalocyanine compounds. The phthalocyanine compound used in the present invention may have a substituent on the aromatic ring for the purpose of adjusting absorption wavelength, improving solubility in a solvent, improving light resistance and the like. Examples of the substituent include an alkyl ether group, an alkyl thioether group, an aryl ether group, an aryl thioether group, an amide group, an amino group, an alkyl ester group, an aryl ester group, a chlorine atom and a fluorine atom. When the aromatic ring has two or more substituents, they may be the same or different, and the substituents may be bonded to each other to form a ring.

The amount of the photothermal conversion dye used is preferably set so that the absorbance at the oscillation wavelength of the light source used is 0.2 or more. When the amount is less than this amount, sufficient heat cannot be obtained and the recording sensitivity is lowered. On the other hand, the photothermal conversion dye also has some absorption in the visible region, and if the amount used is too large, the contrast is lowered. 400 nm to 70
It is preferable to set the upper limit of the amount of the photothermal conversion dye used so that an average transmittance of 0 nm of 60% or more can be secured. Two or more kinds of photothermal conversion dyes can be mixed and used. In that case, the deterioration rate of at least one photothermal conversion dye is 20% or less.

The photothermal conversion dye is preferably contained in at least one of the same layer and an adjacent layer with respect to the layer containing the leuco dye and the reversible developer, and it is contained in the same layer. Is more preferable for obtaining good sensitivity.

Specific examples of the leuco dye used in the present invention include the following, but the present invention is not limited thereto.

3-diethylamino-7-o-chlorophenylaminofluorane, 3-diethylamino-7-m-
Chlorophenylaminofluorane, 3-diethylamino-7-p-chlorophenylaminofluorane, 3-diethylamino-7-o-fluorophenylaminofluorane, 3-diethylamino-7-m-fluorophenylaminofluorane, 3-diethylamino- 7-p-fluorophenylaminofluorane, 3-di-n-butylamino-7-m-chlorophenylaminofluorane, 3-di-n-butylamino-7-p-chlorophenylaminofluorane, 3-di- n-butylamino-7-o-fluorophenylaminofluorane, 3-di-n-butylamino-7-m-fluorophenylaminofluorane, 3-
Di-n-butylamino-7-p-fluorophenylaminofluorane,

3-diethylamino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-o-chlorophenylaminofluorane, 3-
Diethylamino-6-methyl-7-m-chlorophenylaminofluorane, 3-diethylamino-6-methyl-
7-p-chlorophenylaminofluorane, 3-diethylamino-6-methyl-7-o-fluorophenylaminofluorane, 3-diethylamino-6-methyl-7-
o-Tolylaminofluorane, 3-diethylamino-6
-Methyl-7-m-tolylaminofluorane, 3-diethylamino-6-methyl-7-p-tolylaminofluorane, 3-diethylamino-6-methyl-7-o-trifluoromethylphenylaminofluorane, 3 -Diethylamino-6-methyl-7-m-trifluoromethylphenylaminofluorane, 3-diethylamino-6-methyl-7-p-acetylphenylaminofluorane, 3
-Diethylamino-6-methoxy-7-phenylaminofluorane, 3-diethylamino-6-ethoxy-7-
Phenylaminofluorane,

3-di-n-butylamino-6-methyl-
7-phenylaminofluorane, 3-di-n-butylamino-6-methyl-7-o-tolylaminofluorane,
3-di-n-butylamino-6-methyl-7-m-tolylaminofluorane, 3-di-n-butylamino-6-
Methyl-7-p-tolylaminofluorane, 3-di-n
-Butylamino-6-methyl-7-o-chlorophenylaminofluorane, 3-di-n-butylamino-6-methyl-7-m-chlorophenylaminofluorane, 3-
Di-n-butylamino-6-methyl-7-p-chlorophenylaminofluorane, 3-di-n-butylamino-
6-methyl-7-o-fluorophenylaminofluorane, 3-di-n-butylamino-6-methyl-7-m-
Fluorophenylaminofluorane, 3-di-n-butylamino-6-methyl-7-p-fluorophenylaminofluorane, 3-di-n-butylamino-6-methyl-7-o-trifluoromethylphenyl Aminofluorane, 3-di-n-butylamino-6-methyl-7-m-
Trifluoromethylphenylaminofluorane, 3-di-n-butylamino-6-methyl-7-p-trifluoromethylphenylaminofluorane, 3-di-n-butylamino-6-methoxy-7-phenylamino Fluorane, 3-di-n-butylamino-6-ethoxy-7-phenylaminofluorane,

3-di-n-pentylamino-6-methyl-7-phenylaminofluorane, 3-di-n-pentylamino-6-methyl-7-m-trifluoromethylphenylaminofluorane, 3- Pyrrolidyl-6-methyl-7-phenylaminofluorane, 3-piperidyl-6
-Methyl-7-phenylaminofluorane, 3-N-methyl-N-isopentylamino-6-methyl-7-phenylaminofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7- Phenylaminofluorane, 3-N-methyl-N-n-butylamino-6-methyl-7-phenylaminofluorane, 3-N-methyl-N-n-propylamino-6-methyl-7-phenylamino Fluorane, 3-N-ethyl-N-isopentylamino-6-methyl-7-phenylaminofluorane,
3-N-ethyl-N-isopentylamino-6-methyl-7-o-chlorophenylaminofluorane, 3-N-
Ethyl-N-p-tolylamino-6-methyl-7-phenylaminofluorane, 3-N-ethyl-N- (4-ethoxybutyl) amino-6-methyl-7-phenylaminofluorane, 3-diethylamino- 7-dibenzylaminofluorane, 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7-phenylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methyl Fluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3-diethylamino-7- (2
-Chloroanilino) fluoran,

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) ) -3- (1,2-Dimethylindol-3-yl)
Phthalide, 3- (p-dimethylaminophenyl) -3-
(2-Methylindol-3-yl) phthalide, 3-
(P-Dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3-bis (1,
2-Dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,
3-bis (9-ethylcarbazol-3-yl) -5-
Dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6 -Dimethylaminophthalide,

3- (2-Ethoxy-4-aminophenyl) -3- (1-ethyl-2-methylindole-3-
Yl) -4-azaphthalide, 3- (2-ethoxy-4-)
Methylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3-
(2-Ethoxy-4-ethylaminophenyl) -3-
(1-Ethyl-2-methylindol-3-yl) -4
-Azaphthalide, 3- (2-ethoxy-4-propylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy-4-hexylaminophenyl) ) -3- (1-Ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy-4-dimethylaminophenyl) -3- (1-ethyl-2-methylindole-3) −
Yl) -4-azaphthalide, 3- (2-ethoxy-4-)
Diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3-
(2-Ethoxy-4-dipropylaminophenyl) -3
-(1-Ethyl-2-methylindol-3-yl)-
4-azaphthalide, 3- (2-ethoxy-4-dihexylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-
Ethoxy-4-phenylaminophenyl) -3- (1-
Ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy-4-pyridylphenyl) -3- (1-ethyl-2-methylindol-3-
Yl) -4-azaphthalide, 3- (3-ethoxy-4-)
Diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide,

3- (2-Methyl-4-diethylaminophenyl) -3- (1-ethyl-2-methylindole-
3-yl) -4-azaphthalide, 3- (2-ethyl-4)
-Diethylaminophenyl) -3- (1-ethyl-2-
Methylindol-3-yl) -4-azaphthalide, 3
-(2-propyl-4-diethylaminophenyl) -3
-(1-Ethyl-2-methylindol-3-yl)-
4-Azaphthalide, 3- (2-butyl-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-pentyl-4-diethylaminophenyl) -3- (1-Ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-hexyl-4-diethylaminophenyl) -3- (1-ethyl-2-methylindole-3-
Yl) -4-azaphthalide, 3- (2-cyclohexyl-4-diethylaminophenyl) -3- (1-ethyl-
2-Methylindol-3-yl) -4-azaphthalide, 3- (2-cyano-4-diethylaminophenyl)
-3- (1-Ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-nitro-4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) ) -4-Azaphthalide, 3- (2
-Chloro-4-diethylaminophenyl) -3- (1-
Ethyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-bromo-4-diethylaminophenyl) -3- (1-ethyl-2-methylindole-3
-Yl) -4-azaphthalide, 3- (2-methyl-4-)
Diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3-
(2-Ethoxy-4-diethylaminophenyl) -3-
(2-Methylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-methyl-2-methylindol-3-
Yl) -4-azaphthalide, 3- (2-ethoxy-4-)
Diethylaminophenyl) -3- (1-propyl-2-
Methylindol-3-yl) -4-azaphthalide, 3
-(2-Ethoxy-4-diethylaminophenyl) -3
-(1-Butyl-2-methylindol-3-yl)-
4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-pentyl-2-methylindol-3-yl) -4-azaphthalide,

3- (2-Ethoxy-4-diethylaminophenyl) -3- (1-hexyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl)- 3- (1-heptyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-octyl-2-methylindole-3
-Yl) -4-azaphthalide, 3- (2-ethoxy-4)
-Diethylaminophenyl) -3- (1-nonyl-2-
Methylindol-3-yl) -4-azaphthalide, 3
-(2-Ethoxy-4-diethylaminophenyl) -3
-(1-Isopropyl-2-methylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-isobutyl-2-
Methylindol-3-yl) -4-azaphthalide, 3
-(2-Ethoxy-4-diethylaminophenyl) -3
-(1-Isopentyl-2-methylindol-3-yl) -4-azaphthalide,

3- (2-Ethoxy-4-diethylaminophenyl) -3- (1-methyl-2-ethylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl)- 3- (1-ethyl-
2-Propylindol-3-yl) -4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-butylindol-3-
Yl) -4-azaphthalide, 3- (2-ethoxy-4-)
Diethylaminophenyl) -3- (1-ethyl-2-pentylindol-3-yl) -4-azaphthalide, 3
-(2-Ethoxy-4-diethylaminophenyl) -3
-(1-Ethyl-2-hexylindol-3-yl)
-4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-isopropylindol-3-yl) -4-azaphthalide, 3-
(2-Ethoxy-4-diethylaminophenyl) -3-
(1-Ethyl-2-isobutylindol-3-yl)
-4-azaphthalide, 3- (2-ethoxy-4-diethylaminophenyl) -3- (1-ethyl-2-phenylindol-3-yl) -4-azaphthalide,

4,4'-bis (dimethylaminophenyl) benzhydryl benzyl ether, N-chlorophenyl leuco auramine, N-2,4,5-trichlorophenyl leuco auramine, benzoyl leuco methylene blue, p-nitrobenzoyl leuco Methylene blue, 3
-Methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, 3-propylspiro Examples thereof include benzopyran.

The above leuco dyes may be used either individually or in combination of two or more. In addition, toning can be performed by mixing a leuco dye that develops another hue.

The reversible color developer used in the present invention is preferably a compound represented by the following general formula (1), but the present invention is not limited thereto.

[0034]

[Chemical 1]

In the compound represented by the general formula (1), X ¹ and X ² may be the same or different, and each does not contain an oxygen atom, a sulfur atom or a hydrocarbon atomic group at both ends. -Represents a divalent group having a bond as a minimum structural unit. R ¹ represents a single bond or a divalent hydrocarbon group having 1 to 12 carbon atoms. R ² represents a divalent hydrocarbon group having 1 to 18 carbon atoms. Preferred is a divalent hydrocarbon group having 1 to 4 carbon atoms. R ³ represents a monovalent hydrocarbon group having 1 to 24 carbon atoms, preferably a hydrocarbon group having 6 to 24 carbon atoms, and more preferably a hydrocarbon group having 8 to 24 carbon atoms. Furthermore, the sum of carbon numbers of R ¹ , R ² and R ³ is 11 or more and 3
The case of 5 or less is particularly preferable. R ¹ , R ² and R ³ mainly represent an alkylene group and an alkyl group, respectively. R
^In the case of ¹ , it may contain an aromatic ring. f is 0 to 4
R ² and X ^{2 which} are repeated when f is 2 or more may be the same or different.

X ¹ and X ² in the general formula (1) each include a divalent group having a minimum constitutional unit of a —CONH— bond, which does not contain a hydrocarbon atom group, at both ends. Diacylamine (-CONHCO-), diacylhydrazine (-CONHNHCO-), oxalic acid diamide (-NH
COCONH-), acyl urea (-CONHCONH
-, -NHCONHCO-), semicarbazide (-NH
CONHNH-, -NHNHCONH-), acyl semicarbazide (-CONHNHCONH-, -NHCON)
HNHCO-), diacylaminomethane (-CONHC
H ₂ NHCO -), 1- acylamino-1- Ureidometan (-CONHCH ₂ NHCONH -, - NHCON
HCH ₂ NHCO-), malonamide (-NHCOCH
₂ CONH-), 3-acylcarbazic acid ester (-
Examples thereof include groups such as CONHNHCOO- and -OCONHNHCO-, but diacylhydrazine, oxalic acid diamide, and acyl semicarbazide are preferable.

Specific examples of the reversible developer used in the present invention include the following structural formulas (1-1) to (1-).
16), but the present invention is not limited to this.

[0038]

[Chemical 2]

[0039]

[Chemical 3]

The reversible color developer used in the present invention may be used alone or in admixture of two or more. Usually, the amount of the reversible color developer used is 5 to 50 with respect to the colorless or pale leuco dye.
The amount is 00% by mass, preferably 10 to 3000% by mass.

Next, a specific method for producing the reversible thermosensitive recording material of the present invention will be described, but the present invention is not limited thereto.

As a specific example of the method for producing the reversible thermosensitive recording material of the present invention, a colorless or pale-colored leuco dye, a reversible developer, and a photothermal conversion dye are mainly contained, and these are coated on a support or Examples thereof include a method of printing to form a reversible thermosensitive recording layer.

Usually, a colorless or light-colored leuco dye, a reversible color developer, and a photothermal conversion dye are contained in the reversible thermosensitive recording layer. Each compound is dissolved in a solvent or dispersed in a dispersion medium. A method of mixing, a method of dissolving each compound in a solvent or dispersing in a dispersion medium, mixing each compound by heating to dissolve and homogenize, and then cooling.
A layer can be formed by preparing a mixed solution by a method of dissolving it in a solvent or dispersing it in a dispersion medium, and coating or printing it on a support and then drying it.

When the photothermal conversion dye is contained in a layer different from that of the leuco dye and the reversible developer, the photothermal conversion dye is dispersed alone or together with a binder in a layer adjacent to the layer containing the reversible developer. It is preferable to contain

It is also possible to add a binder to the reversible thermosensitive recording layer for the purpose of improving the strength of the reversible thermosensitive recording layer. Specific examples of the binder include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic. Acid ester / methacrylic acid terpolymer, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer, polyvinyl acetate, polyurethane, polyacrylic ester, styrene / butadiene copolymer Polymer, acrylonitrile / butadiene copolymer,
Methyl acrylate / butadiene copolymer, ethylene / vinyl acetate copolymer, ethylene / vinyl chloride copolymer, polyvinyl chloride, ethylene / vinylidene chloride copolymer, polyvinylidene chloride, polycarbonate, polyvinyl butyral and the like can be mentioned. The role of these binders is
The purpose is to keep each material of the composition uniformly dispersed by applying heat for printing and erasing without deviation. Therefore, it is preferable to use a resin having high heat resistance as the binder resin. Recently, high value-added reversible thermosensitive recording materials such as prepaid cards and stored cards are often used, and along with this, high durability products such as heat resistance, water resistance, and adhesiveness are required. Is becoming. Curable resins are particularly preferable for such requirements.

Examples of the curable resin include a thermosetting resin, an electron beam curable resin, an ultraviolet curable resin and the like.
As the thermosetting resin, for example, phenoxy resin, polyvinyl butyral resin, cellulose acetate propionate resin and the like, which are cured by reacting a hydroxyl group and a carboxyl group with a crosslinking agent, can be mentioned. Examples of the crosslinking agent at this time include isocyanates, amines, phenols, epoxies and the like.

Monomers used for electron beam and ultraviolet ray curable resins include monofunctional monomers represented by acrylics, bifunctional monomers, polyfunctional monomers and the like. In particular, in the case of ultraviolet crosslinking, initiation of photopolymerization Agents and photopolymerization accelerators are used.

For the purpose of preventing aging of the reversible thermosensitive recording material, an antioxidant used in rubber products and the like can be added. Further, an antioxidant may be contained in the upper layer or the lower layer of the reversible thermosensitive recording layer. For the purpose of preventing the deterioration of the photothermal conversion dye due to ultraviolet rays, an antiaging agent may be contained in the layer containing the photothermal conversion dye or the upper layer of the layer containing the photothermal conversion dye. Antiaging agents include p, p'-diaminodiphenylmethane, aldol-α-naphthylamine, N, N'-diphenyl-
Examples thereof include amine compounds such as p-phenylenediamine, hydroquinone monobenzyl ether, phenol compounds such as 1,1-bis (p-hydroxyphenyl) cyclohexane, benzotriazole compounds, triazine compounds, benzophenone compounds and benzoate compounds. Other examples include o-phenylene thiourea, zinc salt of 2-aminobenzimidazole, nickel dibutylthiocarbamate, zinc oxide, paraffin and the like. Further, a polymer containing such a monomer having an antioxidant structure as one component of polymerization, or a polymer having a polymer main chain grafted with an antioxidant structure can also be used. It is also possible to use two or more anti-aging agents in combination.

A heat-fusible substance may be contained in the reversible thermosensitive recording layer as an additive for controlling the color developing sensitivity and the decoloring temperature of the reversible thermosensitive recording layer. 60 ° C
Those having a melting point of ~ 200 ° C are preferable, and especially 80 ° C.
Those having a melting point of ˜180 ° C. are preferred. It is also possible to use a sensitizer which is used for general thermal recording paper. For example, waxes such as N-hydroxymethylstearic acid amide, stearic acid amide, and palmitic acid amide, naphthol derivatives such as 2-benzyloxynaphthalene, biphenyl derivatives such as p-benzylbiphenyl and 4-allyloxybiphenyl, 1,2, and the like. -Polyether compounds such as -bis (3-methylphenoxy) ethane, 2,2'-bis (4-methoxyphenoxy) diethyl ether, bis (4-methoxyphenyl) ether, diphenyl carbonate, dibenzyl oxalate, bis (oxalate) Carbonic acid such as p-methylbenzyl) ester or an oxalic acid diester derivative or the like can be added in combination.

As the support used in the reversible thermosensitive recording material of the present invention, paper, various non-woven fabrics, woven fabrics, synthetic resin films, synthetic resin laminated papers, synthetic papers, metal foils, glass and the like, or a combination thereof. The composite sheet can be arbitrarily used according to the purpose, and may be transparent, translucent or opaque. Moreover, it is not limited to these.

The layer structure of the reversible thermosensitive recording material of the present invention is as follows:
An intermediate layer may be provided between the reversible thermosensitive recording layer and the support. In this case, the protective layer and the intermediate layer may be composed of a plurality of layers of 2 layers or 3 layers or more. Further, in the reversible thermosensitive recording layer, a material capable of electrically, magnetically and optically recording information may be contained in another layer, a surface on which the reversible thermosensitive recording layer is provided or an opposite surface. . Also, curling is prevented on the surface opposite to the surface on which the reversible thermosensitive recording layer is provided,
A back coat layer may be provided for the purpose of antistatic.

For the reversible thermosensitive recording layer, protective layer and intermediate layer, diatomaceous earth, talc, kaolin, calcined kaolin,
Pigments such as calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, and urea-formalin resin, as well as higher fatty acid metal salts such as zinc stearate and calcium stearate, paraffin, paraffin oxide, polyethylene, Waxes such as oxidized polyethylene, stearic acid amide, and castor wax, dispersants such as sodium dioctylsulfosuccinate, surfactants, fluorescent dyes, and the like can be included.

[0053]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, the number of parts and percentages in the examples are based on mass.

Example 1 [Measurement of deterioration rate] Photothermal conversion dye (YKR5010 manufactured by Yamamoto Kasei)
3 parts, polyester polyol (Dainippon Ink and Chemicals
Co., Ltd., Burnock D-293-70) 80 parts, cured
Agent (Coronate HL, manufactured by Nippon Polyurethane Co., Ltd.) 11
0 parts, methyl ethyl ketone 300 parts, toluene 300 parts
Mix with glass beads for 2 hours on a paint shaker
And mix the solution with a polyethylene terephthalate sheet (transparent
2 g / m solid content in PET) ²So that it becomes
Then, a sample for measuring the deterioration rate was prepared. Transmission spectrum of this sample
Torr and measure the absorbance at 830 nm (A-1)
After obtaining the temperature conditions of 25 ℃ plus or minus 1 ℃
Using a semiconductor laser with a wavelength of 830 nm,
Irradiation energy 2 J / cm in a 4 cm square area²The leh
The light was irradiated. This laser light irradiation operation is 1000
After repeating the measurement, measure the transmission spectrum of the irradiated area.
Then, the absorbance (A-2) at 830 nm was determined.
The value obtained by subtracting A-2 from A-1 is divided by A-1 and multiplied by 100.
Then, the deterioration rates shown in Table 1 were obtained.

[Preparation of reversible thermosensitive recording material] 3-diethylamino-6-methyl-7-m-trifluoromethylphenylaminofluorane (manufactured by Yamada Chemical Co., Ltd., BLAC)
K 100) 20 parts, N- [3- (p-hydroxyphenyl) propiono] -N'-n-docosanohydrazide 1
00 parts, polyester polyol (Dainippon Ink and Chemicals, Inc., Vernock D-293-70) 50 parts, curing agent (Nippon Polyurethane Co., Ltd., Coronate HL) 5
To 0 parts, 300 parts of methyl ethyl ketone and 300 parts of toluene, 1 part of a photothermal conversion dye (YKR5010 manufactured by Yamamoto Kasei Co., Ltd.) was added, and the mixture was pulverized with glass beads for 5 hours on a paint shaker to obtain a dispersion liquid. A polyethylene terephthalate (PET) sheet was coated with the above dispersion so that the solid content was 7 g / m ^2, and dried to obtain a reversible thermosensitive recording material.

[Print erasure test] The reversible thermosensitive recording material thus obtained was subjected to a temperature condition of 25 ° C plus or minus 1 ° C.
Using a semiconductor laser having a wavelength of 830 nm, irradiation energy of ² J / cm ² was applied to develop color, and the density of the color-developed portion was determined by Macbeth RD918. Next, irradiation energy of 1 J / cm ² was applied to erase the color, and the density of the color-erased portion was determined by Macbeth RD918. The difference between the coloring density and the erasing density (referred to as the first contrast) was 0.65.
Coloring and erasing were repeated by the same operation, and the contrasts at the 200th time and the 1000th time were determined to be 0.64 and 0.63, respectively.

Examples 2 to 3 and Comparative Examples 1 to 3 Example 1 except that the photothermal conversion dyes were changed to those shown in Table 1.
Similarly, the deterioration rate, the first time, the 200th time, the 1000th time
The contrast of the second time was calculated. Regarding the contrast value, ◎ is 0.6 or more, ◯ is 0.4 or more and less than 0.6, and 0.
The results are shown in Table 1 together with Example 1 where Δ is 3 or more and less than 0.4 and x is less than 0.3.

[0058]

[Table 1]

As is clear from the results shown in Table 1, the deterioration rate is 2
The samples of the examples of 0% or less showed clear contrast even after printing was repeated 1000 times.

[0060]

INDUSTRIAL APPLICABILITY According to the present invention, a reversible thermosensitive recording material can be obtained which is capable of forming and erasing an image having a clear contrast stably and repeatedly over 1000 times or more. .

Claims (2)

[Claims] 1. A laser beam having an oscillation wavelength of 830 nm, which contains a normally colorless or pale-colored leuco dye, a reversible developer that develops the color of the leuco dye by heating and reheats it to decolorize it, and a photothermal conversion dye. A reversible thermosensitive recording material characterized in that the deterioration rate of the dye upon irradiation with is 20% or less. 2. The reversible thermosensitive recording material according to claim 1, wherein the leuco dye, the reversible developer and the photothermal conversion dye are in the same layer.