JPH05124339A - Thrmal recording material for infrared laser - Google Patents

Abstract

PURPOSE:To increase thermal sensitivity and enable data to be thermally recorded even using a low-output laser by adding to a thermal sensitive layer an infrared absorption color with high infrared laser absorption efficiency and also high laser beam energy/thermal energy conversion efficiency. CONSTITUTION:A thermal sensitive layer formed consists of a colorless coloring component A, a colorless coloring component B which becomes tinted through a chemical reaction with the component A and an infrared absorption color on a base. At least, one of the coloring components is microcapsulated, and at the same time, the infrared absorption color used is such as expressed by the formula. (Z<1> and Z<2> are an atomic group required for forming a heterocycle containing nitrogen and these can be mutually the same as or different from the other; Z<3> is a divalent hydrogen group required for forming a 5- or 6-membered ring; R<1> and R<2> are H and an alkyl group and can be mutually the same as or different from the other; A is O, S, an imino group and a divalent organic residual group; l, m, n are an integer of 0 or 1; and p, q are an integer of 0 to 2).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to a non-contact heat-sensitive recording material for recording using an infrared laser beam.

[0002]

2. Description of the Related Art A thermal recording system in which a thermal image is recorded on a surface of a thermosensitive recording material having a thermosensitive coloring layer provided on a support by scanning a thermal head in close contact therewith and transmitting thermal energy to the thermosensitive recording layer directly or through a protective layer. Is widely known and is applied to facsimiles, printers and the like. However, in such a thermal recording method, since the thermal head is brought into close contact with the thermal recording material for scanning, the thermal head may be worn or components of the thermal recording material may adhere to the surface of the thermal head as dust. Due to this, there are problems that a recorded image may not be obtained correctly and the thermal head may be destroyed.

A thermal recording system using such a thermal head has the following structural characteristics of the thermal head.
Since there is a limit to the high-speed control of heating and cooling of the heating element and to increase the density of the heating element, there is a drawback that there is a limit to high-speed recording, high density recording and high image quality recording.

In order to solve the above-mentioned drawbacks of the thermal recording method using a thermal head, it has been proposed to perform thermal recording at high speed and high density with a laser beam without contacting the thermal recording material. (For example, JP-A-5
0-23617, JP-A-54-121140, JP-A-57-11090, JP-A-58-56890, JP-A-58-94494, and JP-A-58-134791.
JP-A-58-145493 and JP-A-59-891.
92, JP-A-60-205182, JP-A-62-5.
6195).

However, in such a recording method using a laser beam, the thermosensitive coloring layer generally does not easily absorb light in the visible and near-infrared regions, so that it is necessary for coloring unless the laser output is considerably increased. However, there is a drawback in that it is extremely difficult to produce a small-sized and inexpensive device because it cannot obtain sufficient heat energy. In addition, Japanese Examined Japanese Patent Publication 50-774
No. 1 proposes a method in which microcapsules containing ink are applied to base paper, and intense light is emitted to eject the ink in the capsules to record on the base paper, but the sensitivity is still very low and it has not been realized yet. Has not reached the end.

[0006]

Therefore, many proposals have been made for efficiently absorbing the laser beam in the heat-sensitive recording layer, and generally, the light-absorbing layer according to the wavelength of the laser beam is absorbed in the heat-sensitive recording layer. Substances are being added. In this case, if the light absorbing substance to be added is not white,
The background of the recording material is colored, resulting in poor contrast and poor quality recording.

Generally, white light-absorbing substances are mostly inorganic compounds, but most of them have low light-absorbing efficiency, and therefore it has been desired to develop an organic compound having high light-absorbing efficiency and less coloring. However, in general, organic compounds that absorb light in the visible light region are colored, and the darker the color, the higher the light absorption efficiency. Therefore, it is added to the heat-sensitive recording layer (hereinafter referred to as heat-sensitive layer) as a light-absorbing substance. While it is possible to increase the sensitivity, it is difficult to improve the whiteness of the recording paper.

On the other hand, when an organic compound which does not absorb light having a wavelength in the visible light region and absorbs a laser beam having a wavelength other than the visible light region is used, since the organic compound is not colored, the thermosensitive layer is formed. Even if added, the background of the recording material can be made white.

In the case of using microcapsules, a light absorbing substance that absorbs a laser beam is generally added to the inside or outside of the microcapsules or inside the walls of the microcapsules (called inside or outside of the microcapsules). The light-absorbing substance absorbs the laser beam irradiated imagewise to convert the energy of the laser beam into heat energy, and the microcapsule wall becomes substance-permeable by heating the microcapsules by the heat, An image is recorded on the heat-sensitive recording material by bringing the color-forming components inside and outside the microcapsule into contact with each other.

Therefore, a light-absorbing substance which has a high laser beam absorption efficiency but does not absorb light having a wavelength in the visible light region and which has a high efficiency of converting the energy of the absorbed laser beam into heat energy is added to the heat-sensitive layer. By doing so, the sensitivity of thermal recording of the thermal recording material (hereinafter referred to as thermal sensitivity) can be improved, so that not only thermal recording can be performed by a laser having a low output, but also the whiteness of the recording material can be improved. Is.

Therefore, the inventors of the present invention used an infrared laser to isolate the two color-forming components contained in the heat-sensitive layer with microcapsules and to contain a specific infrared absorbing dye inside and outside the microcapsules. It was found that extremely good results can be obtained when recording is performed by using the above method, and the present invention has been completed. Therefore, an object of the present invention is to provide a heat-sensitive recording material for infrared laser, which enables thermal recording with a high-sensitivity and low-output laser, has less coloring of the upper surface skin, and enables high-quality recording.

[0012]

The above objects of the present invention are as follows.
A color-forming component A which is at least substantially colorless on a support;
A heat-sensitive recording material provided with a heat-sensitive layer containing a substantially colorless color-forming component B, which reacts with the color-forming component A to form a color, and an infrared absorbing dye, wherein at least one of the color-forming components is microencapsulated. In addition, the infrared absorbing dye is

[Chemical 2] It was achieved by an infrared laser heat-sensitive recording material characterized by

In the above Chemical Formula 2, Z ¹ and Z ² are atomic groups necessary for forming a nitrogen-containing heterocycle, and these may be the same or different from each other. Z ³ is a divalent hydrocarbon group necessary for forming a 5- or 6-membered ring, R ¹ and R ² are hydrogen atoms or alkyl groups, and these may be the same or different. A is an oxygen atom, a sulfur atom, an imino group or a divalent organic residue, l, m and n are integers of 0 or 1, and p and q are integers of 0, 1 or 2.

The color-forming component used in the present invention is a component which produces a color-forming reaction upon contact with a substance, specifically, a combination of a photodecomposable diazo compound and a coupler or a combination of an electron-donating dye precursor and an acidic substance. Is preferred. The photodecomposable diazo compound used in the present invention is a compound that reacts with a developer called a coupling component described below to develop a desired hue, and decomposes when receiving light of a specific wavelength before the reaction. However, it is a diazo compound that has no color-forming ability even when the coupling component acts. The hue in this coloring system is mainly determined by the diazo dye produced by the reaction of the diazo compound and the coupling component. Therefore, as is well known, the coloring hue can be easily changed by changing the chemical structure of the diazo compound or the chemical structure of the coupling component, and almost any coloring hue can be obtained depending on the combination. it can.

The photodecomposable diazo compound in the present invention mainly refers to an aromatic diazo compound, and more specifically, a compound such as an aromatic diazonium salt, a diazosulfonate compound or a diazoamino compound. The diazonium salt is
A compound represented by the general formula ArN ₂ ⁺ X ⁻ (wherein
Ar represents a substituted or unsubstituted aromatic moiety,
N ₂ ⁺ represents a diazonium group, and X ⁻ represents an acid anion. ).

It is generally said that the photolysis wavelength of a diazonium salt is its absorption maximum wavelength. It is known that the absorption maximum wavelength of diazonium salt changes from about 200 nm to about 700 nm depending on its chemical structure (“Photolysis and chemical structure of photosensitive diazonium salt” by Takahiro Tsunoda and Ao Yamaoka, Japan photo Academic Journal 29 (4) 197-205 (1965)). That is, when a diazonium salt is used as a photodecomposable compound, it decomposes with light of a specific wavelength according to its chemical structure, and if the chemical structure of the diazonium salt is changed, the same coupling component and The hue of the dye also changes.

Many diazosulfonate compounds that can be used in the present invention are known, and they can be obtained by treating each diazonium salt with a sulfite.
The diazoamino compound that can be used in the present invention is a compound in which the diazo group is coupled with dicyandiamide, sarcosine, methyltaurine, N-ethylanthranic acid-5-sulphonic acid, monoethanolamine, diethanolamine, guanidine or the like. Is. Details of these diazo compounds are described in, for example, JP-A-2-136286.

As a light source for photolysis of diazo compounds,
Various light sources that emit light of a desired wavelength can be used, for example, various light sources such as various fluorescent lamps, xenon lamps, xenon flash lamps, mercury lamps of various pressures, photographic flashes, and strobes. or,
In order to make the light fixing zone compact, the light source unit and the exposure unit may be separated by using an optical fiber.

Coupling components for forming a dye by coupling with the diazo compound used in the present invention include, for example, 2-hydroxy-3-naphthoic acid anilide and resorcin as well as JP-A-62-146678. The ones mentioned can be mentioned. Further, by using two or more of these coupling components in combination, an image with any color tone can be obtained. Therefore, the present invention is not limited to a monochromatic heat-sensitive recording material.

Since the coupling reaction between these diazo compounds and the coupling component easily occurs in a basic atmosphere, a basic substance may be added in the heat sensitive layer. As the basic substance, a poorly water-soluble or water-insoluble basic substance or a substance that generates an alkali when heated is used. Examples thereof are inorganic and organic ammonium salts, organic amines, amides, urea and thiourea and their derivatives, thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidazolines, triazoles. And nitrogen-containing compounds such as morpholines, piperidines, amidines, formazines and pyridines. Specific examples of these are, for example,
It is described in JP-A-61-291183. Two or more basic substances may be used in combination.

The electron-donating dye precursor used in the present invention is not particularly limited, but it has a property of developing a color by donating an electron or accepting a proton such as an acid, A compound which is substantially colorless and has a partial skeleton such as lactone, lactam, sultone, spiropyran, ester, amide, etc., and these partial skeletons are ring-opened or cleaved upon contact with a developer is used. In particular,
Examples include crystal violet lactone, benzoyl leuco methylene blue, malachite green lactone, rhodamine B lactam, 1,3,3-trimethyl-6′-ethyl-8′-butoxyindolinobenzospiropyran.

As a developer for these color formers,
An acidic substance such as a phenol compound, an organic acid or a metal salt thereof, or an oxybenzoic acid ester is used, and specific examples thereof are described in JP-A-61-291183. The color-forming component used in the present invention is from the viewpoint of improving the transparency of the heat-sensitive layer, from the viewpoint of raw storability such as preventing contact of the color-forming component at room temperature (prevention of fog), and color-sensitivity such that color is developed with desired laser energy. From the viewpoint of controlling, etc., the color-forming components of A and B are used by being encapsulated in different microcapsules, or one of A and B is microencapsulated and used.

Next, the infrared absorbing dye represented by Chemical Formula 2 used in the present invention will be described in detail. In the chemical formula 2, Z ¹ and Z ² are atomic groups necessary for forming a nitrogen-containing heterocycle (which may have a substituent). Examples of such atomic groups include thiazole series nuclei (for example, thiazole, 4-methylthiazole, 4-phenylthiazole, 5-methylthiazole, 5-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenyl). Thiazole and 4- (2-thienyl) -thiazole etc.);

Benzothiazole series nuclei (eg benzothiazole, 5-chlorobenzothiazole, 5-methylbenzothiazole, 6-methylbenzothiazole, 5,
6-dimethylbenzothiazole, 5-bromobenzothiazole, 5-phenylbenzothiazole, 5-methoxybenzothiazole, 6-methoxybenzothiazole,
5,6-dimethoxybenzothiazole, 5,6-dioxymethylenebenzothiazole, 5-hydroxybenzothiazole, 6-hydroxybenzothiazole and 4,
5,6,7-tetrachlorobenzothiazole etc.);

A core of the naphthothiazole series (for example, naphtho [2,1-d] thiazole, naphtho [1,2-d] thiazole, 5-methoxynaphtho [1,2-d] thiazole, 5-ethoxynaphtho [1, 2-d] thiazole, 3
-Methoxynaphtho [2,1-d] thiazole and 7-methoxynaphtho [2,1-d] thiazole, etc.); thionaphthene [7,6-d] thiazole series nuclei (for example, 7-methoxythionaphthene [7,6] -D] thiazole);

Nuclei of the oxazole series (eg 4-methyloxazole, 5-methyloxazole, 4-phenyloxazole, 4,5-diphenyloxazole, 4-
Ethyloxazole, 4,5-dimethyloxazole, 5-phenyloxazole and the like); benzoxazole series nuclei (for example, benzoxazole, 5-chlorobenzoxazole, 5-methylbenzoxazole, 5-
Phenylbenzoxazole, 6-methylbenzoxazole, 5,6-dimethylbenzoxazole, 5-methoxybenzoxazole, 6-methoxybenzoxazole, 5-hydroxybenzoxazole, 6-hydroxybenzoxazole and the like);

Nucleotides of the naphthoxazole series (eg naphtho [2,1-d] oxazole and naphtho [1,2-
d] Oxazole etc.); selenazole series nuclei (eg 4-methylselenazole and 4-phenylselenazole etc.); benzoselenazole series nuclei (eg benzoselenazole, 5-chlorobenzoselenazole, 5-methylbenzoselena) Sol, 5,6-dimethylbenzoselenazole, 5-methoxybenzoselenazole, 5-methyl-
6-methoxybenzoselenazole, 5,6-dioxymethylenebenzoselenazole, 5-hydroxybenzoselenazole, 4,5,6,7-tetrahydrobenzoselenazole and the like);

Naphthoselenazole series nuclei (eg naphtho [2,1-d] selenazole and naphtho [1,2-
d] selenazole etc.); thiazoline series nuclei (eg thiazoline, 4-methylthiazoline, 4-hydroxymethyl-4-methylthiazoline and 4,4-bis-hydroxymethylthiazoline etc.); oxazoline series nuclei (eg oxazoline etc.) , Nuclei of the serenazoline series (eg, serenazoline etc.);

2-quinoline series nuclei (eg quinoline,
6-methylquinoline, 6-chloroquinoline, 6-methoxyquinoline, 6-ethoxyquinoline, 6-hydroxyquinoline and the like); 4-quinoline series nuclei (eg quinoline, 6-methoxyquinoline, 7-methylquinoline and 8)
-Methylquinoline etc.); 1-isoquinoline series nuclei (eg isoquinoline and 3,4-dihydroisoquinoline etc.);

3-isoquinoline series nuclei (eg isoquinoline etc.); 3,3-dialkylindolenine series nuclei (eg 3,3-dimethylindolenine, 3,3-dimethyl-5-chloroindolenine and 3,3). , 5-indolenine, etc.); pyridine series nuclei (eg pyridine and 5
-Methylpyridine etc.);

Benzimidazole series nuclei (eg 1-
Ethyl-5,6-dichlorobenzimidazole, 1-hydroxyethyl-5,6-dichlorobenzimidazole, 1-ethyl-5-chlorobenzimidazole, 1-
Ethyl-5,6-dibromobenzimidazole, 1-ethyl-5-phenylbenzimidazole, 1-ethyl-
5-fluorobenzimidazole, 1-ethyl-5-cyanobenzimidazole, 1- (β-acetoxyethyl) -5-cyanobenzimidazole, 1-ethyl-5
-Chloro-6-cyanobenzimidazole, 1-ethyl-5-fluoro-6-cyanobenzimidazole, 1-
Ethyl-5-acetylbenzimidazole, 1-ethyl-5-carboxybenzimidazole, 1-ethyl-5
-Ethoxycarbonylbenzimidazole, 1-ethyl-5-sulfamylbenzimidazole, 1-ethyl-
5-N-ethylsulfamylbenzimidazole, 1-
Ethyl-5,6-difluorobenzimidazole, 1-
Ethyl-5,6-dicyanobenzimidazole, 1-ethyl-5-ethylsulfonylbenzimidazole, 1-
Ethyl-5-methylsulfonylbenzimidazole, 1
-Ethyl-5-trifluoromethylbenzimidazole, 1-ethyl-5-trifluoromethylsulfonylbenzimidazole, 1-ethyl-5-trifluoromethylsulfinylbenzimidazole, etc.);

And a core of the imidazo [4,5-b] quinoxaline series (eg 1,3-diisobutylimidazo [4,
An atomic group necessary for completing 5-b] quinoxaline and 1,3-bis (2-ethoxyethyl) imidazo [4,5-b] quinoxaline) can be mentioned.

Z ³ is a divalent hydrocarbon group necessary for forming a 5- or 6-membered ring (for example, —CH ₂ —CH ₂ —,
_{-CH 2 -CH 2 -CH 2 -,} - CH = CH- and -C
H = CH-CH ₂ -) a and, these 5-membered or 6-membered ring, benzene ring, may be condensed with naphthalene ring.

[0034] R ¹ and R ² are a hydrogen atom or an alkyl group, and the alkyl group may have a substituent. Examples of the substituent in the alkyl group include, for example, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, iso-butyl group, t-butyl group, n-amyl group, t-amyl group, n-
Hexyl group, n-octyl group, t-octyl group, 2-hydroxyethyl group, 3-ethoxypropyl group, 4-hydroxybutyl group, 2-acetoxyethyl group, carboxymethyl group, 2-ethoxyethyl group, 3-carboxy Propyl group, 2-sulfoethyl group, 3-sulfopropyl group,
4-sulfobutyl group, 3-sulfatepropyl group, 4
-Sulfate butyl group, N- (methylsulfonyl)-
Examples thereof include a carbamylmethyl group, a 3- (acetylsulfamyl) propyl group, and a 4- (acetylsulfamyl) butyl group.

In the present invention, "alkyl group" means cyclic alkyl group (eg cyclohexyl group), allyl group (CH ₂ ═CH—CH ₂ —), aralkyl group (eg benzyl group, phenethyl group, α). -Naphthylmethyl group, β
-Nartylmethyl group, etc.), a substituted aralkyl group (eg, carboxybenzyl group, sulfobenzyl group, hydroxybenzyl group, etc.) and the like. Therefore, R ¹ and R ² may be the above alkyl groups.

A is an oxygen atom, a sulfur atom, an imino group (which may have a substituent, for example, ═NH, a methylimino group, an ethylimino group, a propylimino group, a butylimino group, a benzylimino group and the like are included. .) Or a divalent organic residue. As such a divalent organic residue,
For example, the groups represented by the following chemical formulas 3, 4 and 5 can be mentioned.

[Chemical 3]

[Chemical 4]

[Chemical 5]

R ³ , R ⁴ and R ⁵ in the formulas ³ , ⁴ and ⁵ are hydrogen atoms or alkyl groups (the same as R ¹ and R ² in the formula ² ). In Formula 2,
It is preferable that l, m and n are either 0 or 1, and p and q are 0, 1 or 2.

Specific examples of the infrared absorbing dye represented by the chemical formula 2 include the compounds represented by the following chemical formulas 6 to 26, but the present invention is not limited thereto. ..

[Chemical 6]

[Chemical 7]

[Chemical 8]

[Chemical 9]

[Chemical 10]

[Chemical 11]

[Chemical 12]

[Chemical 13]

[Chemical 14]

[Chemical 15]

[Chemical 16]

[Chemical 17]

[Chemical 18]

[Chemical 19]

[Chemical 20]

[Chemical 21]

[Chemical formula 22]

[Chemical formula 23]

[Chemical formula 24]

[Chemical 25]

[Chemical formula 26]

The compounds represented by Chemical Formulas 6 to 26 (referred to as cyanine compounds) are indan-2-one, cyclohexanone, cyclopentanone, cyclohexen-3-one, cyclopentadiene-5-one or 1,2,2. Three
A compound obtained by subjecting a cyclic ketone compound such as 4-tetrahydronaphthalen-2-one and a dehydration condensation reaction of dicyanomethane, barbituric acid or a derivative thereof, or rhodanine or a derivative thereof to a cyclic ketone compound is used in a general field of cyanine chemistry. It can be easily obtained by reacting with a benzothiazolium salt, a benzoxazolium salt, a quinolium salt or a naphthothiazolium salt.

In the present invention, the use amount of the above infrared absorbing dye is not particularly limited, but it is 0.04 to
It is preferable to include an amount of 0.5 g / m ^{2 in} the heat sensitive layer. Further, the addition is carried out at any one or more locations inside, outside or inside the wall of the microcapsule.

Any of an interfacial polymerization method, an internal polymerization method and an external polymerization method can be adopted for producing the microcapsules used in the present invention. In particular, a core substance containing a color forming component is water-soluble. It is preferable to employ a method of emulsifying the polymer in an aqueous solution in which the polymer is dissolved and then forming a wall of the polymer substance around the oil droplets.

The reactant forming the polymer substance is added inside the oil droplet and / or outside the oil droplet. Specific examples of the polymer substance include polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, and styrene-acrylate copolymer. Preferred polymeric substances are polyurethanes, polyureas, polyamides, polyesters and polycarbonates, particularly preferably polyurethanes and polyureas. Two or more polymer substances can be used in combination. Specific examples of the water-soluble polymer include gelatin, polyvinylpyrrolidone, polyvinyl alcohol and the like.

For example, when polyurea is used as the capsule wall material, polyisocyanates such as diisocyanate, triisocyanate, tetraisocyanate and polyisocyanate prepolymer, and polyamines such as diamine, triamine and tetraamine, and amino groups are used. The microcapsule wall can be easily formed by reacting a prepolymer containing two or more of the above, piperazine or a derivative thereof, a polyol and the like by an interfacial polymerization method in an aqueous solvent.

Further, for example, the composite wall made of polyurea and polyamide or the composite wall made of polyurethane and polyamide is added, for example, by using polyisocyanate and acid chloride or polyamine and polyol, after adjusting the pH of the emulsifying medium as the reaction liquid. It can be prepared by warming. Details of the method for producing a composite wall composed of these polyurea and polyamide are described in JP-A-58-6.
6948.

The core material of the microcapsule used in the present invention can contain the infrared absorbing dye as described above, but may be contained outside the microcapsule or in the microcapsule wall. .. It may be contained in two or more places at the same time.

Further, a solid sensitizer may be added to swell the microcapsule wall at the time of heating with a laser beam to increase the thermal sensitivity. The solid sensitizer may be selected from those referred to as plasticizers for polymers used as microcapsule walls, and those having a melting point of 50 ° C. or higher, preferably 120 ° C. or lower, and solid at room temperature can be selected and used. For example, when the wall material is made of polyurea or polyurethane, a hydroxy compound, a carbamic acid ester compound, an aromatic alkoxy compound, an organic sulfonamide compound, an aliphatic amide compound, an arylamide compound or the like is preferably used.

In the present invention, it is also possible to use a color forming aid. The coloring aid that can be used in the present invention is a substance that increases the coloring density at the time of laser heating recording or lowers the minimum coloring temperature, lowers the melting point of the coloring component or the basic substance, or capsules. This is to create a situation in which the color-forming component A and the color-forming component B are likely to react with each other by the action of lowering the softening point of the wall.

Examples of the color-forming assistant include phenol compounds, alcoholic compounds, amide compounds, sulfonamide compounds, and the like. Specific examples are p-tert-octylphenol, p-benzyloxyphenol, phenyl p-oxybenzoate, and the like. Examples thereof include benzyl carbanylate, phenethyl carbanylate, hydroquinone dihydroxyethyl ether, xylylenediol, N-hydroxyethyl-methanesulfonic acid amide, N-phenyl-methanesulfonic acid amide. These may be contained in the core substance or may be added to the outside of the microcapsules as an emulsified dispersion.

In the present invention, when only one of the color forming components is microencapsulated, it is preferable to microencapsulate the diazo compound or the electron donating dye precursor. In this case, the coupler or the developer or the infrared absorbing dye may be used by being dispersed in a solid state, or after the coupler or the developer or the infrared absorbing dye is dissolved in an organic solvent that is sparingly soluble or insoluble in water. It is also possible to mix this with an aqueous phase having a water-soluble polymer containing a surfactant as a protective colloid, and to use it in the form of an emulsion-dispersed dispersion. In the latter case, the heat sensitive layer can be transparent.

The organic solvent used in preparing the emulsified dispersion can be appropriately selected from high boiling point oils. Among them, preferable oils include dimethylnaphthalene, diethylnaphthalene, diisopropylnaphthalene, dimethylbiphenyl, diethylbiphenyl, diisopropylbiphenyl, diisobutylbiphenyl, 1-methyl-1-dimethylphenyl-1-phenylmethane, 1-ethyl-, in addition to esters. 1-dimethylphenyl-1
-Phenylmethane, 1-propyl-1-dimethylphenyl-1-phenylmethane, triallylmethane (for example,
Tritolyl methane, toluyl diphenyl methane), terphenyl compounds (eg terphenyl), alkyl compounds (eg terphenyl), alkylated diphenyl ethers (eg propyl diphenyl ether),
Examples include hydrogenated terphenyl (eg, hexahydroterphenyl), diphenyl ether and the like.

Among these, it is particularly preferable to use the esters from the viewpoint of the emulsion stability of the emulsion dispersion. Examples of the esters include phosphates (eg, triphenyl phosphate, tricresyl phosphate, butyl phosphate, octyl phosphate, cresyl diphenyl phosphate), phthalates (dibutyl phthalate, 2-ethylhexyl phthalate, ethyl phthalate, phthalate). Octyl acid, butylbenzyl phthalate), dioctyl tetrahydrophthalate, benzoic acid ester (ethyl benzoate, propyl benzoate, butyl benzoate, isopentyl benzoate, benzyl benzoate), abietic acid ester (ethyl abietic acid, benzyl abietic acid) ), Dioctyl adipate, isodecyl succinate, dioctyl azelate, oxalate ester (dibutyl oxalate, dipentyl oxalate), diethyl malonate, maleate ester (dimethyl maleate, diethyl maleate) Dibutyl maleate), tributyl citrate, sorbate (methyl sorbate, ethyl sorbate, butyl sorbate), sebacate (dibutyl sebacate, dioctyl sebacate), ethylene glycol esters (formic acid monoester and diester, Butyric acid monoester and diester, lauric acid monoester and diester, palmitic acid monoester and diester, stearic acid monoester and diester, oleic acid monoester and diester),
Examples thereof include triacetin, diethyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate, borate esters (tributyl borate, tripentyl borate) and the like. Among these, the use of tricresyl phosphate alone or in combination is preferable because the emulsion dispersion stability of the developer is particularly good.

It is possible to use the above oils in combination, or to use in combination with other oils. In the present invention, an auxiliary solvent may be added to the above organic solvent as a low boiling point dissolution aid. As such an auxiliary solvent, for example, ethyl acetate, isopropyl acetate, butyl acetate, methylene chloride and the like can be mentioned as particularly preferable ones.

The water-soluble polymer to be contained as a protective colloid in the aqueous phase mixed with the oil phase containing these components is appropriately selected from known anionic polymers, nonionic polymers and amphoteric polymers. However, polyvinyl alcohol, gelatin, cellulose derivatives and the like are preferable.

The surfactant contained in the aqueous phase may be appropriately selected from anionic or nonionic surfactants that do not cause precipitation or aggregation by acting on the protective colloid. it can. Preferred surfactants include sodium alkylbenzene sulfonate, sodium alkylsulfate, dioctyl sodium sulfosuccinate, polyalkylene glycol (for example, polyoxyethylene nonylphenyl ether), and the like.

In the emulsified dispersion of the present invention, an oil phase containing the above components and an aqueous phase containing a protective colloid and a surfactant are used by a means commonly used for fine particle emulsification such as high speed stirring and ultrasonic dispersion. Then, they can be mixed and dispersed to obtain easily. The ratio of the oil phase to the water phase (weight of oil phase / weight of water phase) is preferably 0.02 to 0.6, particularly 0.1.
It is preferably ˜0.4. If it is 0.02 or less, the amount of the aqueous phase is too large to be diluted and sufficient color development cannot be obtained.
On the other hand, when it is 6 or more, the viscosity of the liquid becomes high, which causes inconvenience in handling and a decrease in coating liquid stability.

If desired, pigments, waxes, hardeners, etc. may be added to the heat-sensitive layer. When the heat-sensitive layer solution prepared as described above is applied onto a support, a blade is used. A known water-based or organic solvent-based coating solution such as a coating method, an air knife coating method, a gravure coating method, a roll coating method, a spray coating method, a dip coating method, and a bar coating method is used.

In this case, in order to apply the heat-sensitive layer liquid safely and uniformly and to maintain the strength of the coating film, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, starches, gelatin, polyvinyl alcohol are used as the binder in the present invention. , Carboxy-modified polyvinyl alcohol, polyacrylamide, polystyrene and its copolymers, polyester and its copolymers, polyethylene and its copolymers, epoxy resins, acrylate and methacrylate resins and their copolymers, polyurethane resins and polyamide resins Etc. can also be used in combination with microcapsules. In the heat-sensitive layer, the total amount of the color-forming component and the infrared absorbing dye is 0.
It is desirable that the coating be applied so as to be 1 to 10 g / m ² and that the thickness of the layer be 1 to 10 μm.

The support used in the present invention may be transparent or opaque. As the transparent support, it is preferable to use a support which does not absorb a laser beam to be irradiated and has dimensional stability that does not deform with respect to heat generated during laser irradiation. When a transparent support is used, a laser beam may be irradiated through the transparent support for recording. The thickness of the support is 10 μm to 200 μm
m is used.

As such a transparent support, for example,
Polyester film such as polyethylene terephthalate or polybutylene terephthalate, cellulose derivative film such as cellulose triacetate film, polystyrene film, polypropylene film, polyolefin film such as polyethylene film, polyimide film, polyvinyl chloride film, polyvinylidene chloride film,
Examples thereof include polyacrylic films and polycarbonate films, which can be used alone or in combination.

On the other hand, examples of the opaque support of the recording material include paper, synthetic paper, aluminum vapor deposition base, and the above-mentioned transparent support coated with a pigment or the like. In this case,
In order to irradiate the laser beam from the heat-sensitive layer side so that the heat-sensitive layer can be efficiently absorbed, it is preferable to use an opaque support of the recording material having a high laser-beam reflectivity. As the support used in the present invention,
In particular, a polyester film that has been subjected to heat treatment and antistatic treatment is preferable.

In the present invention, in order to prevent the entire heat-sensitive layer from peeling off from the support, it is desirable to provide an undercoat layer on the support before applying the heat-sensitive layer liquid containing microcapsules and the like. As the undercoat layer, an acrylic acid ester copolymer, polyvinylidene chloride, SBR, aqueous polyester or the like can be used, and the film thickness is
0.1 to 0.5 μm is desirable.

The undercoat layer made of these compositions is applied by the same application method as that for applying the heat-sensitive layer liquid.
The coating amount is preferably set to from 1 to 20 g / m ^2, particularly preferably a 3 to 10 g / m ^2. The laser beam used in the present invention has a wavelength in the infrared region. Specific examples thereof include helium-neon laser, argon laser, carbon dioxide laser, Y
Examples thereof include AG laser and semiconductor laser.

Since the heat-sensitive layer of the recording material of the present invention contains the infrared absorbing dye at one or more locations inside, outside or inside the wall of the microcapsule, the infrared absorbing dye absorbs the laser beam irradiated. To convert that energy into heat energy. As a result, the microcapsules are heated to become substance permeable and the internal pressure is increased. As a result, the reactive substances inside and outside the microcapsules permeate the microcapsule walls to develop color.

[0064]

INDUSTRIAL APPLICABILITY The heat-sensitive recording material for infrared laser of the present invention has high absorption efficiency of infrared laser and high efficiency of converting energy of laser beam into heat energy even though it has little absorption of visible light. Since the heat-sensitive layer contains an absorbing dye, it is excellent in heat sensitivity, can be heat-recorded by a small-sized and low-power laser, and can record with good quality with little background coloring.

[0065]

EXAMPLES The present invention will be described in more detail with reference to Examples below.
The present invention is not limited to this. In addition, "part" which shows an addition amount shows a "weight part."

Example 1. Preparation of capsule liquid Crystal violet lactone (leuco dye) 14
g, 75 wt% ethyl acetate solution of xylylene diisocyanate and trimethylolpropane (3: 1) adduct (Takenate D-110N: trade name of capsule wall material manufactured by Takeda Pharmaceutical Co., Ltd.) 60 g, and ultraviolet absorber (Sumithorpe) 200: trade name of Sumitomo Chemical Co., Ltd.) 2 g, 1-
It was added and dissolved in a mixed solvent of 55 g of phenyl-1-xylylethane and 55 g of methylene chloride.

100 g of an aqueous solution of 8% by weight of polyvinyl alcohol, 40 g of water and 2% by weight of a sodium salt of dioctyl sulfosuccinate (dispersing agent) 1.4 were obtained.
After mixing with an aqueous solution of g, emulsification was performed for 5 minutes at 10,000 rpm using an ace homogenizer (manufactured by Nippon Seiki Co., Ltd.). After further adding 150 g of water to the obtained emulsion, an encapsulation reaction was performed at 40 ° C. for 3 hours to prepare a capsule solution having an average particle size of 0.7 μm.

Preparation of color developer emulsion dispersion 8 g of the developer represented by the following formula 27, 4 g of the developer represented by the formula 28 below, 30 g of the developer represented by the formula 29 below, and the following formula 4 g of the infrared absorbing dye represented by 30 was used, 8.0 g of 1-phenyl-1-xylylethane and 30 g of ethyl acetate
It was dissolved in a mixed solution of g. The obtained solution was mixed with 100 g of an aqueous 8% by weight polyvinyl alcohol solution, 150 g of water and an aqueous solution of 0.5 g of sodium dodecylbenzenesulfonate, and then ace homogenizer (manufactured by Nippon Seiki Co., Ltd.).
With an average particle size of 0.5 at 10,000 rpm at room temperature
The emulsion was emulsified for 5 minutes to obtain an emulsified dispersion.

[Chemical 27]

[Chemical 28]

[Chemical 29]

[Chemical 30]

Preparation of heat-sensitive recording material 5.0 g of the above capsule liquid, the above-mentioned developer emulsion dispersion 10.
A liquid obtained by stirring and mixing 0 g and 5.0 g of water with a thickness of 70 μm
m transparent polyethylene terephthalate (PET) support was coated to a solid content of 15 g / m ² and dried. On the heat-sensitive layer formed as described above, the protective layer liquid having the composition shown in Table 1 below was dried to a thickness of 2
The transparent heat-sensitive recording material according to the present invention was prepared by coating and drying so that the thickness became μm.

[0070]

[Table 1] ──────────────────────────────────── Composition of the protective layer liquid 10% by weight polyvinyl alcohol 20 g Water 30 g 2% by weight Sodium salt of sulfosuccindiooctyl 0.3 g Polyvinyl alcohol 3 g, Kaolin dispersion prepared by dispersing 100 g of water and 35 g of kaolin in a ball mill 3 g Hydrin Z-7 (Chukyo Yushi Co., Ltd.) 0.5 g ─── ──────────────────────────────────

From the heat-sensitive layer side of the heat-sensitive recording material produced as described above, a semiconductor laser beam having a wavelength of 780 nm (GaAs junction laser) was imagewise irradiated to obtain a blue recorded image. The laser output is 1 on the surface of the heat sensitive layer.
The energy was adjusted to 40 mJ / mm ^{2 in} milliseconds. The reflection density of the colored portion of the obtained image was measured using a Macbeth densitometer and was 1.45.

Example 2. Instead of the crystal violet lactone used in Example 1 and the infrared absorbing dye represented by Chemical formula 8, 2-anilino-3-methyl-6-N was used, respectively.
-Ethyl-N-butylaminofluorane and the following compound 31

[Chemical 31] A heat-sensitive recording material was prepared and an image was recorded in the same manner as in Example 1 except that the infrared absorbing dye represented by the above was used, and a transparent black image was obtained. The transmission density of the colored portion of the obtained image was measured using a Macbeth densitometer and found to be 1.63.
Met.

Example 3. Preparation of capsule liquid

[Chemical 32] 50 parts of the compound represented by
g, 50 parts tricresyl phosphate, 150 parts trimethylolpropane trimethacrylate and 75% by weight ethyl acetate solution of trimethylolpropane 3: 1 adduct of m-xylylene diisocyanate (Takenate D110).
N: Trade name of capsule wall material manufactured by Takeda Pharmaceutical Co., Ltd.)
200 parts were uniformly mixed to obtain an oil phase solution.

On the other hand, 7% by weight of polyvinyl alcohol (PVA217E: saponification degree 88 to 89%, polymerization degree 1,
700: 600 parts of Kuraray Co., Ltd.) was prepared as a water-soluble polymer aqueous solution. Then 5 with hot bath
The dissolver was attached to a liter stainless steel pot, the polymer aqueous solution was added, and then the oil phase solution was added while stirring the dissolver. While observing with a microscope, the emulsion was emulsified and dispersed so that the average particle size of the emulsion was about 1.5 μm. After emulsifying and dispersing, loosen the stirring and put in a warm bath.
The encapsulation reaction was completed in 3 hours while keeping the temperature in the pot at 40 ° C by passing warm water of 2 ° C. 25 ml of an ion exchange resin (MB-3: trade name of Organo Co., Ltd.) was added to the obtained liquid, stirred, and then filtered to obtain a capsule liquid.

Preparation of Dispersion A The substances shown in Table 1 below were mixed and dispersed in a dissolver in advance, and then Dynomill (Willie A. Bacofen.
Dispersion A was obtained by emulsifying and dispersing with A.G. (manufactured by WILLY A. BACHOFEN AG) so that the average particle size was 2 μm.

[0076]

[Table 1] ──────────────────────────────────── 15% by weight polyvinyl alcohol aqueous solution 30 parts (PVA -205 Kuraray Co., Ltd. product name) coupler 33 of chemical formula 4.3

[Chemical 33] 0.6 part of coupler of chemical formula 34

[Chemical 34] 5.0 parts of the organic basic compound of Chemical formula 35

[Chemical 35] Color development improving agent of Chemical formula 36 3.0 parts

[Chemical 36] Infrared absorbing dye of Chemical formula 37 0.5 parts

[Chemical 37] ────────────────────────────────────

Preparation of Dispersion B The substances shown in Table 2 below were mixed and stirred to obtain Dispersion B.

[Table 2] ──────────────────────────────────── Univer 70 (a product manufactured by Shiraishi Industry Co., Ltd. Name) 20 parts Caobright (trade name of Thiele Kaolin Company) 40% by weight sodium hexametaphosphate aqueous solution 0.5 parts water 30 parts ──────────────── ─────────────────────

Preparation of thermosensitive recording material 20 parts by weight of the above-mentioned capsule liquid, 20 parts by weight of dispersion liquid A, 7 parts by weight of dispersion liquid B and a surfactant (Nissan Rapizol 13-90: trade name of NOF CORPORATION) 2% by weight aqueous solution 1. 5 parts were stirred and mixed, and coated on a polyethylene terephthalate (PET) support having a thickness of 70 μm so that the solid content was 15 g / m ^2, and dried to form a heat-sensitive layer. Further, a mixture having the composition shown in Table 3 below was applied on the heat-sensitive layer so that the thickness after drying was 2 μm to form a protective layer, and the heat-sensitive recording material of the present invention (hereinafter referred to as recording material) Was produced.

[0079]

[Table 3] Composition of protective layer ─────────────────────────────────── 10% by weight polyvinyl alcohol 20 g water 30 g 2 wt% sodium salt of dioctyl sulfosuccinate 0.3 g Polyvinyl alcohol 3 g, water 100 g and kaolin 35 g dispersed in a ball mill Kaolin dispersion 3 g Hydrin Z-7 (trade name of Chukyo Yushi Co., Ltd.) 0.5 g ── ───────────────────────────────────

The obtained recording material was imagewise irradiated with a semiconductor infrared laser beam (GaAs junction laser) having a wavelength of 780 nm from the heat sensitive layer side to obtain a blue image. The laser beam output is 1 at the surface of the heat-sensitive layer of the recording material.
The energy was adjusted to 40 mJ / mm ^{2 in} milliseconds. Then, the entire surface of the recording material was exposed and optically fixed using Ricopy Super Dry 100 (manufactured by Ricoh Co., Ltd.). The reflection density of the obtained blue recorded image was measured by a Macbeth reflection densitometer and found to be 1.12.

Comparative Example 1. When a recording material was prepared and an image was recorded in exactly the same manner as in Example 1 except that the infrared absorbing dye used in Example 1 was not used, no image could be recorded.

Comparative Example 2. Instead of the infrared absorbing dye used in Example 1,

[Chemical 38] When a recording material was prepared and an image was recorded in the same manner as in Example 1 except that the compound represented by the formula (1) was used, the reflection density of the obtained image was 0.24.

Claims (3)

[Claims] 1. A heat-sensitive layer containing, on a support, at least a substantially colorless color-forming component A, a substantially colorless color-forming component B that reacts with the color-forming component A to form a color, and an infrared absorbing dye. A heat-sensitive recording material provided, wherein at least one of the color-forming components is microencapsulated,
The infrared absorbing dye is the following chemical formula 1 (In the formula, Z ¹ and Z ² are a group of atoms necessary for forming a nitrogen-containing heterocycle, which may be the same or different from each other. Z ³ forms a 5-membered or 6-membered ring. And R ¹ and R ² are hydrogen atoms or alkyl groups which may be the same or different from each other, A is an oxygen atom, a sulfur atom, an imino group or a divalent organic residue. Groups, l, m and n are integers of 0 or 1, p and q are 0,
It is an integer of 1 or 2. ) The thermosensitive recording material for infrared lasers, characterized in that 2. The heat-sensitive recording material according to claim 1, wherein the color-forming component A is a photodecomposable diazo compound and the color-forming component B is a coupler. 3. The heat-sensitive recording material according to claim 1, wherein the color-forming component A is an electron-donating dye precursor and the color-forming component B is a color developer.