JPH1029377A - Thermosensitive recording material and thermal recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the infrared laser beam absorbing efficiency and reduce the degree of coloring of a texture by providing a thermally sensitive layer containing an infrared absorptive coloring matter consisting of organic silver salt, its developing agent and a specific merocyanine compound, and a water-soluble binder, on a support. SOLUTION: A thermally sensitive layer containing an infrared absorptive coloring matter consisting of organic silver salt, its developing agent and a specific merocyanine expressed by a formula, and a water-soluble binder, is formed on a support. In the formula, R is a 1-6C alkyl group or a 5-10C aryl group or a hataryl group; R<1> -R<4> are H, halogen, groups of alkyoxy, aryl or acyloxy, aryloxy or alkoxy carbonyl, alkyl or arylsulfonyl, carbamoyl, acyl, acylamide, alkyl or arylamino, alkyl, aryl, hetaryl groups; A is -COR, etc.; B is -NHR, etc.; Y is vinylene; Z is a 5-7 membered ring; and n is an integer of 3-5.

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 a heat recording method using the same, and more particularly to a non-contact heat-sensitive recording material for infrared laser recording using infrared laser light and a low-temperature recording material using the same. The present invention relates to a thermal recording method capable of performing high-sensitivity recording even with an energy laser.

[0002]

2. Description of the Related Art A thermal head is brought into close contact with a surface of a heat-sensitive recording material having a heat-sensitive recording layer (hereinafter referred to as a heat-sensitive layer) provided on a support, and heat energy is transferred to the heat-sensitive layer directly or through a protective layer. Thermal recording systems for recording images are widely known, and are applied to facsimile machines, 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 is worn or the components of the thermal recording material are scum on the surface of the thermal head. There are drawbacks that a recorded image cannot be obtained correctly due to the adhesion, and that the thermal head is destroyed. In addition, the thermal recording method using such a thermal head has limitations in high-speed control of heating / cooling of the heating elements and in increasing the density of the heating elements due to the structural characteristics of the thermal head. There is a drawback that there is a limit in achieving recording, high-density recording, and high-quality recording.

In order to solve the above-mentioned disadvantages of the thermal recording method using a thermal head, it has been proposed to perform thermal recording at high speed and high density without contact with a thermal recording material using a laser beam. (For example, Japanese Patent Application Laid-Open
No. 3617, JP-A-54-121140, JP-A-57
-11090, JP-A-58-56890, JP-A-5-5680
8-94494, JP-A-58-134791, JP-A-58-145493, JP-A-59-89192,
JP-A-60-205182, JP-A-62-56195
No.).

However, in such a recording method using a laser beam, the heat-sensitive layer generally does not easily absorb light in the visible and near-infrared regions. There is a drawback that energy is not obtained and it is extremely difficult to produce a small and inexpensive device. Japanese Patent Publication No. 50-774 proposes a method in which microcapsules containing ink are applied to a base paper, and a strong light is applied to eject the ink in the capsule to record on the base paper. Is so low that it has not yet been put to practical use.

Therefore, there have been many proposals for efficiently absorbing a laser beam in the heat-sensitive layer. In general, a light-absorbing substance suitable for the wavelength of the laser beam is added to the heat-sensitive layer. ing. In this case, if the light-absorbing substance to be added is not white, the background of the recording material is colored, and only low-quality recording with low contrast can be obtained. However, in general, white light-absorbing substances are many in inorganic compounds, but most of them have low light-absorbing efficiency. On the other hand, organic compounds suitable for absorbing laser light are generally colored to absorb light in the visible light region, and the darker the color, the higher the light absorption efficiency. When added to the heat-sensitive layer as an absorbing substance, the sensitivity can be increased, but it is difficult to reduce the background coloring of the recording paper.

[0007] Therefore, there has been a need for a light-absorbing substance that has a high efficiency of converting light energy to heat energy (light-to-heat conversion efficiency) even in a small amount.

Further, such a heat-sensitive recording material is configured not to develop color with low heat energy in order to maintain a stable storage state. Therefore, considerable heat energy is required to obtain a desired color state. As a result, the dynamic range is narrowed by the threshold value of the heat energy up to color development, and there is a disadvantage that it is difficult to obtain a high-gradation image. In addition, the burden on the apparatus for coloring is considerably increased.

On the other hand, a heat-sensitive recording material to which predetermined heat energy has been applied develops a color in accordance with the heat energy, and an image is visualized. In this case, it is known that the image density of the heat-sensitive recording material after the image is recorded increases with time in a state of storage at room temperature. Therefore, there is a problem that the image density is different between immediately after recording and after a predetermined time has elapsed.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and has high absorption efficiency of infrared laser light, less coloring of the background, and high quality recording. To provide a thermosensitive recording material for an infrared laser, and to stabilize the density of an image after recording using the thermosensitive recording material, and to increase the dynamic range of a laser beam for recording an image or the like. It is possible to obtain a high-gradation, high-precision image or the like with sufficient securing, and to reduce the burden on the heating beam generating means for generating the laser beam, thereby making the apparatus simple and inexpensive. It is an object to provide a thermal recording method.

[0011]

Means for Solving the Problems In the heat-sensitive layer, the absorption efficiency of the laser beam is high, but the light absorption of the wavelength in the visible light region is small, and the efficiency of converting the energy of the absorbed laser beam into thermal energy is high. By adding a light absorbing substance, it is possible to improve the sensitivity of thermal recording of the thermosensitive recording material, not only to enable thermal recording with a low output laser, but also to improve the whiteness of the recording material, The present inventors have found that a merocyanine compound having a specific structure is suitable as the light-absorbing substance, and furthermore, to obtain an excellent heat-sensitive recording material by combining an organic silver salt as a color-forming substance. When recording was performed using an infrared laser, it was found that extremely good results could be obtained.

That is, the heat-sensitive recording material of the present invention is an infrared laser comprising a support and a heat-sensitive layer containing at least an organic silver salt, a developer of an organic silver salt, an infrared absorbing dye, and a water-soluble binder. Heat-sensitive recording material, wherein the infrared absorbing dye is a merocyanine compound represented by the following general formula (I).

In the above invention, the organic silver salt may be contained in a solid dispersion state, or at least one of the organic silver salt and the organic silver salt developer may be microencapsulated and contained.

In the above invention, it is preferable that the organic silver salt contains a development accelerator.

In the heat-sensitive recording material for an infrared laser of the present invention, the heat-sensitive layer contains the merocyanine compound, and the merocyanine compound absorbs the irradiated laser light and converts the energy into heat energy. Therefore, the absorption efficiency of the laser beam is increased, and the reaction between the organic silver salt, which is a coloring component, and the developer of the organic silver salt is promoted. Furthermore, when the merocyanine compound is contained in any one or more of the inside of the microcapsule, the outside, and the inside of the wall, the energy of the laser light is converted into heat energy by the merocyanine compound, whereby the microcapsule is formed. As a result, the organic silver salt and the developer of the organic silver salt existing inside and outside the microcapsule penetrate through the microcapsule wall and develop color, as a result of being heated to become material-permeable and increasing the internal pressure.

In addition, the present inventors perform a preheating step, a heating step after thermal recording, or a preheating step and a heating step after thermal recording when performing thermal recording using the thermosensitive recording material. It has been found that the recording density can be improved, the image density after recording can be stabilized, and recording with excellent gradation can be performed.

That is, the thermal recording method according to claim 5 of the present invention provides a merocyanine represented by the following general formula (I) on a support at least as an organic silver salt, a developer of an organic silver salt, and an infrared absorbing dye. A thermosensitive layer containing a compound and a water-soluble binder is provided, and a thermosensitive recording material that develops a color at a concentration according to the applied thermal energy is irradiated with an infrared laser beam modulated according to recording information. A first step of imagewise heating the thermosensitive recording material to a predetermined coloring temperature, and uniformly heating the entire surface of the thermosensitive recording material heated imagewise at a predetermined temperature lower than the coloring temperature of the thermosensitive recording material. And a second step of uniformly preheating the entire surface of the heat-sensitive recording material to a predetermined temperature lower than the color development temperature. , The preheated feeling A second step of irradiating the recording material with an infrared laser beam modulated in accordance with the recording information and imagewise heating the thermosensitive recording material to a predetermined coloring temperature. .

The thermal recording method according to claim 7 of the present invention provides a merocyanine represented by the following general formula (I) on a support at least as an organic silver salt, a developer of an organic silver salt, and an infrared absorbing dye. A first step in which a heat-sensitive layer containing a compound and a water-soluble binder is provided, and the entire surface of the heat-sensitive recording material that develops color at a concentration corresponding to the applied thermal energy is uniformly preheated to a predetermined temperature lower than the color-forming temperature; Irradiating the preheated thermosensitive recording material with an infrared laser beam modulated in accordance with recording information, and heating the thermosensitive recording material to a predetermined coloring temperature in an imagewise manner; A third step of uniformly heating the entire surface of the heated thermosensitive recording material at a predetermined temperature lower than the coloring temperature of the thermosensitive recording material.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the thermosensitive recording material according to the present invention will be described in more detail.

The organic silver salt contained in the heat-sensitive layer of the heat-sensitive recording material for infrared laser of the present invention is a colorless or white silver salt which is stable to light, and when heated with a developer, Silver is produced by a redox reaction. Such an organic silver salt is a silver salt of an organic compound having an imino group, a mercapto group or a carboxyl group, and specific examples thereof include the following.

1) Silver salt of an organic compound having an imino group Silver saccharin, silver phthalazinone, silver benzotriazole, etc. 2) Silver salt of an organic compound having a mercapto group or a thione group 3- (2-carbonylethyl) -4-oxy Methyl-4
-Silver salt of thiazoline-2-thione, 3-mercapto-4
Silver salts of organic compounds having a carboxyl group, such as silver stearate and silver behenate.

Among these, from the viewpoints of being white and stable to light, being excellent in moisture resistance, being usable in combination with a mild developer, and being known for excellent color toning agents, Silver behenate is most preferred.

In the heat-sensitive recording material for infrared laser of the present invention, desalted and purified organic silver salt is preferably used from the viewpoint of recording a high-density image using a high-density organic silver salt. . Here, desalination purification means, for example, when preparing an organic silver salt by adding silver nitrate to a salt of an organic acid formed by adding an alkali to an organic acid, a nitrate salt by-produced by the addition of the silver nitrate Is to be removed from the system. Such desalting purification is preferably performed by an ultrafiltration method using a semipermeable membrane that allows the passage of nitrate but not the organic silver salt, or a centrifugation method.

In the recording layer of the thermosensitive recording material for infrared laser of the present invention, a latent image is formed when exposed to light, and a reduction reaction to an organic silver salt, that is, a photosensitivity capable of rapidly performing development. When a silver halide having the formula (1) is contained adjacent to the organic silver salt, the heat-sensitive recording material of the present invention also has a function as a photosensitive recording material for recording by a laser beam. The silver halide in this case is appropriately selected from known silver halides such as silver chloride, silver bromide, silver chlorobromide, silver iodide, silver iodobromide, silver chloroiodobromide and the like. be able to.

When the silver halide is contained adjacent to the organic silver salt, the silver halide is contained in a system in which the organic silver salt is present, but a part of the organic silver salt is halogenated by adding a silver halide forming agent. It is preferable to contain it by changing it to silver.

As the silver halide forming agent, CaB
inorganic halides such as r ₂ , KBr, KCl and HBr; onium halides such as NH ₄ Br and NH ₄ Cl;
Examples thereof include halogen-donating compounds such as halogenated carbon and N-halides such as N-bromosuccinimide.

When silver halide is used in combination, the content is preferably from 1 to 30 mol% based on the organic silver salt.

Next, the organic silver salt developer will be described.
The developer used in the heat-sensitive recording material of the present invention is a reducing agent having an action of reducing an organic silver salt to generate silver when heated. Characteristics such as not affecting the color tone.

Examples of such a developer include hydroxycoumarone or hydroxycoumarans, sulfamidophenols or sulfamidonaphthols, hydradones, hirooxamic acids, bis-β-naphthols, indane-1,3. -Diones, aminophenols or aminonaphthols, pyrazolin-5-ones, hydroxylamines, reductones, hydrazines, hydroquinones, bisphenol A, bisphenol B
Such as polyphenols, gallic acid, gallic acid ester,
Phenylenediamines, hydroxyindanes, 1,4
-Dihydroxypyridines, amide oximes, hydroxy-substituted aliphatic carboxylic acid aryl hydrazides, N-
Hydroxyureas, phosphonamidophenols, phosphonamidoanilines, α-cyanophenylacetic esters, sulfonamidoamilines and the like, among these, each compound represented by the following formula, octyl gallate, It is preferable to use propyl gallate, ethyl gallate or methyl gallate.

[0030]

Embedded image

The method for solid dispersion of the organic silver salt in the present invention includes, for example, a water-soluble polymer compound such as an organic silver salt and polyvinyl alcohol, and if necessary, a color tone agent, an antifoggant, a dispersant, and water. And disperse it to several microns or less by a ball mill, sand mill or the like. On the other hand, the reducing agent is similarly solid-dispersed or completely dissolved in an aqueous solution such as polyvinyl alcohol. The respective liquids thus obtained are blended to prepare a solid dispersion coating liquid, which is coated on a support to obtain a recording material.

Further, in the present invention, from the viewpoint of preventing the reduction reaction between the organic silver salt and the developer at room temperature to extend the shelf life of the thermosensitive recording material for infrared lasers and reduce the fogging with time, It is preferable that at least one of a salt and an organic silver salt developer is encapsulated in microcapsules. When only one of the organic silver salt and the developer of the organic silver salt is microencapsulated, the other is used by dispersing it in a solid, completely dissolved in an aqueous solution of polyvinyl alcohol or the like, or dissolved in an organic solvent. After being converted into an oil phase, the oil phase can be mixed with an aqueous phase containing a water-soluble polymer and used in the form of an emulsified dispersion. In the latter case, the heat-sensitive layer can be made transparent. When both the organic silver salt and the organic silver salt developer are microencapsulated, it is preferable that these are encapsulated in separate microcapsules, but the purpose is only to obtain an aqueous coating solution. Then, they may be included in the same microcapsule.

The microcapsules usable in the present invention are:
It is a thermo-responsive microcapsule that isolates a substance contained at room temperature, is not destroyed by pressure, heat, or the like at the time of heating, and makes the wall of the microcapsule material-permeable.

As a method for producing such microcapsules, known production methods such as an interfacial polymerization method, an internal polymerization method, and an external polymerization method can be employed. In particular, organic silver salts or organic silver salts can be used. An oil phase component obtained by adding a capsule wall material (polymer material) to a core material obtained by dissolving or dispersing a developer in an organic solvent is emulsified in an aqueous solution in which a water-soluble polymer is dissolved. It is preferable to adopt an interfacial polymerization method in which a wall made of the polymer of the capsule wall material is formed around the capsule wall.

As the organic solvent, it is preferable to use a non-aqueous solvent having a boiling point of 150 ° C. or less, such as a carboxylic acid ester such as ethyl acetate, butyl acetate and isoamyl acetate, toluene, xylene and phosphate ester.

The reactant forming the capsule wall material is added inside the oil droplet and / or outside the oil droplet.

Specific examples of the capsule wall material include polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, polyamic acid, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer and the like.
Preferred capsule wall materials are polyurethane, polyurea, polyamide, polyester, and polycarbonate, and polyurethane and polyurea are preferred because capsules that are hard to break are obtained. These polymer substances can be used in combination of two or more kinds.

Specific examples of the water-soluble polymer include gelatin, polyvinylpyrrolidone, and polyvinyl alcohol.

For example, when polyurea or polyurethane is used as the capsule wall material, (a) a polyvalent isocyanate such as diisocyanate, triisocyanate, tetraisocyanate, polyisocyanate prepolymer and (b) diamine , Triamine, tetraamine and other polyamines, prepolymers containing two or more amino groups, piperazine or its derivatives, polyhydric alcohols and the like, or water in an aqueous solvent by an interfacial polymerization method to easily form microcapsule walls. Can be formed. The microcapsules in this case are preferable because their walls are dense.

For the composite wall composed of polyurea and polyamide or the composite wall composed of polyurethane and polyamide, for example, the pH of an emulsifying medium as a reaction solution is adjusted by using polyisocyanate and acid chloride or polyamine and polyhydric alcohol. Thereafter, it can be prepared by heating. For details of the method for producing a composite wall composed of these polyurea and polyamide, see JP-A-58-1983.
-66948. The capsule made of polyamic acid is formed, for example, by an interfacial reaction between a polystyrene-maleic anhydride copolymer and a polyvalent amine.

The following isocyanate compounds are particularly preferred as the wall material of the microcapsules used in the thermosensitive recording material for infrared laser of the present invention.

The isocyanate-based compound used here includes known isocyanate monomers (1) urethane-modified, (2) allophanate-modified, (3) isocyanurate-modified, (4) buret-modified, and (5) ) Modified carbodiimides, (6) modified products such as blocked isocyanates, and (7) polymeric MDI,
Linear polymer of 4'-diphenylmethane diisocyanate (MDI).

As the isocyanate monomer forming the modified product, tolylene diisocyanate (TDI), 4,4
4'-diphenylmethane diisocyanate (MDI),
Xylylene diisocyanate (XDI), naphthylene diisocyanate (NDI), paraphenylene diisocyanate (PPDI), tetramethyl xylylene diisocyanate (TMXDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IP
DI), lysine diisocyanate (LDI), isopropylidene bis (4-cyclohexyl isocyanate)
(IPC), hydrogenated xylylene diisocyanate (hydrogenated X
DI), cyclohexyl diisocyanate (CHD
I) and tolidine diisocyanate (TODI). The structure of this isocyanate monomer is shown below, but the isocyanate monomer used in the present invention is not limited to these. These are described in detail, for example, in "Synthesis, blending, functionalization and application development of latest polyurethane" (Technical Information Association, 1989).

[0044]

Embedded image

[0045]

Embedded image

These isocyanate monomers are used after being modified into various isocyanate modified products as described above for the purpose of improving undesirable physical properties such as toxicity, controlling the reaction rate, and improving the mixing ratio. Can be Next, the modified form will be described. (1) The urethane-modified product is obtained by modifying an isocyanate monomer (or diisocyanate) with a shortage of polyol. (2) The modified allophanate is formed by adding an isocyanate group to a urethane group. (3) The modified isocyanurate has an isocyanurate ring in the molecule and tends to have improved heat resistance. (4) The modified buret is a compound in which an isocyanate group is added to a urea bond, and is a compound from which free isocyanate is removed. (5) In the modified carbodiimide, a carbodiimide bond is generated from a 2 mol isocyanate group by a decarbonation reaction. Furthermore, after uretonimine is formed when the isocyanate is added, carbodiimide and uretonimine coexist in equilibrium. (6) Blocked isocyanate is obtained by reacting various blocking agents to temporarily mask the activity of the isocyanate group.
Phenolic blocking agents such as xylenol, oximes,
Active hydrogen compounds such as lactams and alcohols are exemplified.

As the capsule wall material of the thermosensitive recording material for infrared laser of the present invention, specifically, from the viewpoint of safety and availability, isocyanate compounds represented by the following formulas (a) to (k) are mentioned. Can be

[0048]

Embedded image

[0049]

Embedded image

The reactant forming the capsule wall material is preferably heated after emulsification and dispersion. The heating conditions are preferably 30 to 80 ° C. for 30 minutes to 4 hours. If the temperature is lower than 30 ° C., the reaction requires a long time and the reaction proceeds only incompletely. When the temperature exceeds ℃, it becomes difficult to control the reaction, which is not preferable.

For example, when an isocyanate compound is used as a capsule wall material, an oil phase component obtained by further adding at least one isocyanate compound to a dispersion obtained by dispersing an organic silver salt in an organic solvent as described above. After being added to an aqueous solution containing a water-soluble binder such as gelatin,
Stirring is performed to obtain a dispersion in which the oil phase component is dispersed in an aqueous solution, and the entire dispersion is heated to, for example, about 40 to 90 ° C. to form a wall material of microcapsules.

At this time, the average particle size of the obtained microcapsules is preferably 0.1 to 3.0 μm,
More preferably, it is 0.2 to 1.2 μm. By controlling the particle diameter in the above range, the transparency of the heat-sensitive layer is improved, and there are advantages such that an image can be observed with transmitted light in a shark castene.

Next, the infrared absorbing dye used in the heat-sensitive recording material of the present invention will be described. The compound used as the infrared absorbing dye in the thermosensitive recording material for an infrared laser of the present invention is a merocyanine compound represented by the following general formula (I).

[0054]

Embedded image

In the above formula, R is a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms or a substituted or unsubstituted aryl group or hetaryl group having 5 to 10 carbon atoms (for example, cyclopentyl group, t-butyl). Group, 2-ethoxyethyl group,
n-hexyl group, benzyl group, 3-chlorophenyl group,
2-imidazolyl group, 2-naphthyl group, 4-pyridyl group, methyl group, ethyl group, phenyl group, m-tolyl group, etc.).

R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom; a halogen atom such as a chlorine atom, a bromine atom, a fluorine atom and an iodine atom; a cyano group; a methoxy group;
An alkoxy group such as an ethoxyethoxy group or a benzyloxy group; an aryloxy group such as a phenoxy group, a 3-pyridyloxy group, a 1-naphthoxy group, or a 3-phenyloxy group;
Acyloxy groups such as acetoxy group, benzoyloxy group and phenylacetoxy group; phenoxycarbonyl group, m
Aryloxycarbonyl groups such as -methoxyphenoxycarbonyl group; alkoxycarbonyl groups such as methoxycarbonyl group, butoxycarbonyl group and 2-cyanoethoxycarbonyl group; alkylsulfonyl groups such as methanesulfonyl group and cyclohexanesulfonyl group; β-toluenesulfonyl group Arylsulfonyl groups such as N-phenylcarbamoyl group, N-phenylcarbamoyl group, N-phenyl-N-ethylcarbamoyl group, N-isopropylcarbamoyl group and the like; and 6-quinolinesulfonyl group and 2-naphthalenesulfonyl group. An acyl group such as a benzoyl group, a phenylacetyl group, or an acetyl group; a p-toluenesulfonamide group, a benzamide group,
Acylamido group such as acetamide group; alkylamino group such as diethylamino group, ethylbenzylamino group, isopropylamino group; arylamino group such as anilino group, diphenylamino group, N-ethylanilino group; substituted or unsubstituted alkyl group, aryl Or a hetaryl group (for example, those exemplified above as R);
R, R ¹ , R ² , R ³ and R ⁴ are two of these.
The two may combine with each other to form a substituted or unsubstituted 5- to 7-membered aliphatic or heterocyclic ring (eg, tetrahydropyran, cyclopentene, 4,4-dimethylcyclohexene, etc.).

A is -COR, -CO_TwoR, -CONH
R, -CONR_Two, -SO_TwoR, -SO_TwoNHR, -S
O_TwoNR_Two, -SR or -CN, B is -NHR,
-NR _Two, -OR, -SR, or R; or
A and B are bonded to each other, or R^ThreeOr R^FourAnd join
And a substituted or unsubstituted 5- to 7-membered aliphatic or heterocyclic ring
(E.g., 2-furanone, thiohydantoin, rhodanine
Etc.) may be formed.

Y is a carbon atom substituted by a dialkyl group, vinylene (-CH = CH-), an oxygen atom, a sulfur atom, a selenium atom, a tellurium atom or -NR-. Z is an atomic group forming a 5- to 7-membered aliphatic or heterocyclic ring (for example, benzenethiazole, benzindole, quinoline, etc.).
Note that n in the formula is an integer of 3 to 5.

Among the merocyanine compounds used as the infrared absorbing dye in the present invention, those wherein Y is a sulfur atom or a dimethyl group-substituted carbon atom, those which directly bond to the carbon atom at the R ² position, and those wherein Z is a benzothiazole ring , An indole ring or a quinoline ring, and a compound in which B is bonded to R ³ to form a furanone ring.

The above merocyanine compounds are described in Journal of American Chemical Society (JA).
m. Chem. Soc. Vol. 73, p. 5326 (19
51) and U.S. Pat. No. 2,177,402.

The concentration of the above-mentioned merocyanine compound as an infrared absorbing dye in the heat-sensitive layer may be determined as appropriate, but is usually 0.05 to 0.5 g / m ² .

Preferred specific examples of the merocyanine compound represented by the general formula (I) include the following compounds, but the present invention is not limited thereto.

[0063]

Embedded image

[0064]

Embedded image

The merocyanine compound used in the present invention is
It has the function of increasing the whiteness of the background of the heat-sensitive recording material for infrared lasers and the absorption efficiency of infrared lasers, and may be contained in any of the heat-sensitive recording layers as a part to be contained. When at least one of the coloring components of the dye is microencapsulated, for example, it may be contained in the core material of the microcapsule, contained outside the microcapsule, or contained in the microcapsule wall. Further, the merocyanine compound may be contained in two or more places at the same time.

The water-soluble binder used in the present invention has a function of binding the developer and the microcapsules contained in the heat-sensitive layer and a function of adhering the heat-sensitive layer to the support. Examples of such a water-soluble binder include gelatin and / or a gelatin derivative (for example, phthalated gelatin), a water-soluble polymer such as polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, arabic gum, polyvinylpyrrolidone, casein, styrene- Examples include various emulsions such as butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylate, and ethylene-vinyl acetate copolymer.

The amount of the binder used is preferably 0.5 to 5 g / m ² in terms of solid content.

In the present invention, from the viewpoint of accelerating the reduction reaction between the organic silver salt and the developer at the time of heating, adjusting the color tone of the image and performing rapid development, a development accelerator (color tone agent)
Is preferably contained in the heat-sensitive layer.

This development accelerator is preferably used when the resulting image is desired to be a dark color image, especially a black image. The amount used ranges from about 0.0001 mol to about 2 mol, preferably from about 0.0005 mol to about 1 mol, per 1 mol of the organic silver salt.
Effective development accelerators vary with the organic silver salt and developer used, but the most common development accelerators are heterocyclic organic compounds containing at least two heteroatoms, wherein the heterocycle contains At least one nitrogen atom is present.

These are described, for example, in US Pat.
No. 0,254. Specific examples of such a development accelerator include, for example, phthalazone (phthalazinone), anhydrous phthalates, 2-acetylphthalazinone,
2-phthalylphthalazinone and others, JP-A-50-67
Examples include substituted phthalazinones described in JP-A-132, which are preferably used in the present invention.

Examples of other effective development accelerators include pyrazolin-5-ones, cyclic imides, and quinazolinones as described in JP-A-46-6077. Specific examples of these include phthalimide, N-hydroxyphthalimide, N-potassium phthalimide, and silver phthalimide. Alternatively, phthalazinones are also effective as development accelerators.

Other effective development accelerators are disclosed in
And mercapto compounds as described in JP-A Nos. 9-5019 and 49-5020. Other examples include oxazinediones described in JP-A-50-2542, phthalazinediones described in JP-A-50-67641, and 58-114217.
Uracils as described in U.S. Pat. No. 3,782,941 as described in U.S. Pat. No. 3,782,941.
Hydroxyhydroxyphthalimides, as described in West German Patent Application Publication Nos. 2,140,406, 2,141,063 and 2,220,597.
Substituted phthalimides, West German Patent Application Publication No. 2,22
Phthalazinone derivatives, such as those described in U.S. Pat. No. 0,618, can be used as well.

In the heat-sensitive recording material for infrared laser of the present invention, it is preferable to further take the following measures from the viewpoint of preventing heat fogging and stabilizing the background after image formation.

First, it is well known that mercury compounds have a remarkable effect on preventing heat fog and stabilizing the background after image formation. However, from the viewpoint of environmental pollution, it is difficult to use these compounds. Since it is not preferable, in the present invention, JP-A-49-10724, JP-A-48-2842,
N, as described in JP-A-48-8194,
It is preferred to use N-halogeno compounds such as -halogenosuccinimide, N-halogenoacetamide, N-halogenoxazolinone, N-halogenobenzotriazole, and N-halogenobenzimidazole.

Also, US Pat. No. 3,645,739, JP-A-49-125016 and JP-A-49-1307
No. 20, 50-57619, 50-39264, etc .; higher fatty acids; arylsulfonates such as tetrahalogenophthalic acid or anhydride, benzenesulfonic acid, p-toluenesulfonic acid; benzene Use of arylsulfinic acids such as sulfinic acid and p-toluenesulfinic acid or salts thereof; lithium salts of higher fatty acids such as lithium myristate, lithium stearate, lithium behenate, lithium palmitate and lithium laurate as acid stabilizers. be able to.

Other acid stabilizers include salicylic acid, p-
Alkyl-substituted benzoic acids such as hydroxybenzoic acid, tetrabromobenzoic acid, tetrachlorobenzoic acid, p-acetamidobenzoic acid, pt-butylbenzoic acid, phthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, dicitric acid, 5 '5'-Methylenebissalicylic acid, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid and the like are also effective. These acid stabilizers not only prevent thermal fogging, but also have the effect of preventing background discoloration upon exposure to white light after image formation and improving shelf life.

Other compounds effective for preventing thermal fogging and preventing photodiscoloration include benzotriazole and its derivatives, tetrazole and its derivatives, thiouracils,
Compounds such as -phenyl-5-mercaptotetrazole, azole thioethers or blocked azolethiones disclosed in JP-A-47-318, tetrazolylthio compounds disclosed in U.S. Pat. No. 3,700,457; 3,707,377 and 4,
No. 108,455, photosensitive halogeno organic oxidizing agents; polybrominated organic compounds such as 2,4-bis (tribromomethyl) -s-triazine and polybromoalkylsulfonyl compounds shown in 3,874,946. compounds, the 4,546,075 trihalomethyl tetrazole derivatives as shown in JP, trihalomethyl benzimidazole and benzoxazole counterparts, or benzothiazole counterparts, R ^a -CX disclosed in JP-a-59-57234 A compound represented by _2- ^Rb (X represents halogen: ^Ra , ^Rb represents a group such as acyl, oxycarbonyl, oxysulfonyl, alkylsulfonyl, allylsulfonyl, aralkylsulfonyl, carboxyl, sulfo, sulfamoyl, etc.), US Patent No. 4,465,761
No. 4,452,88.
2-trihalomethyl oxazole derivative shown in No. 5, a heterocyclic compound having a trihalomethyl group shown in 4,756,999, and a compound represented by the following formula disclosed in European Patent No. 622,666. Is valid.

[0078]

Embedded image

In the above formula, R ⁵ , R ⁶ and R ⁷ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, a thioalkyl group, a perhalogenated alkyl group,
Or a cycloalkyl group.

The effect of the present invention is particularly remarkable when the above-mentioned heat fogging photodiscoloration inhibitor is used in combination with a thermoresponsive capsule.

In order to increase the thermal sensitivity by adding a sensitizer in an emulsified state or a solid state in order to swell the microcapsule wall during infrared laser light heating for forming the wall material of the microcapsule. Can also. The sensitizer is selected from polymer plasticizers used as a capsule wall material and has a melting point of 50 ° C. or higher, preferably 15 ° C.
Those which are solid at 0 ° C. or lower and at room temperature can be selected and used. For example, when the capsule wall material is made of polyurea or polyurethane, a hydroxy compound, a carbamate compound, an aromatic alkoxy compound, an organic sulfonamide compound, an aliphatic amide compound, an arylamide compound and the like are preferably used.

Further, in the present invention, a coloring aid can be used. The color-forming auxiliary that can be used in the present invention is a substance that increases the color density during laser heating recording or lowers the minimum color-forming temperature. This is for creating a situation in which the developer and the developer easily react.

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

The support used in the present invention may be transparent or opaque. Opaque supports include paper,
Examples thereof include synthetic paper, paper obtained by laminating a polymer film on paper, aluminum vapor-deposited base, and polymer film coated with a white pigment. In this case, it is preferable to use a support having high laser light reflectivity in order to irradiate the laser light from the heat-sensitive layer side and efficiently absorb the laser light into the heat-sensitive layer.

On the other hand, as the transparent support, it is preferable to use a support that does not absorb the laser beam to be irradiated and has dimensional stability that does not deform due to heat generated during laser beam irradiation. In this case, recording can be performed by irradiating a laser beam through the transparent support. The thickness of the support is 10 μm to 200 μm.

Examples of such a transparent support include polyester films such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate film, and polyolefins such as polystyrene film, polypropylene film and polyethylene film. Examples thereof include a film, a polyimide film, a polyvinyl chloride film, a polyvinylidene chloride film, a polyacrylic acid copolymer film, and a polycarbonate film. These can be used alone or in combination. Films that can be used as the transparent support preferably have a haze (degree of cloudiness) of 3% or less.

As the support used in the present invention, a polyester film which has been subjected to heat treatment and antistatic treatment is particularly preferred.

The method for producing the film is not particularly limited as long as the above-mentioned object can be achieved. Specific examples include a method of producing a film by heating and melting, extruding, cooling, solidifying, stretching, and heat setting.

The support may contain inorganic fine particles, an antioxidant, an antistatic agent, a dye and the like as long as the object of the present invention is not hindered.

The inorganic fine particles that can be used here include I
Group A, IIA, IVA, VIA, VIIA, VIII, I
Group B, IIB, IIIB, IVB, oxides, hydroxides, sulfides, nitrides, halides, carbonates, acetates, phosphates, phosphites, organic carboxylate of each element, Silicates,
Examples include titanates, borates and their hydrated compounds, composite compounds centered on them, and natural mineral particles.
Specifically, Group IA element compounds such as lithium fluoride, borax (sodium borate hydrate), magnesium carbonate, magnesium phosphate, magnesium oxide (magnesia), magnesium chloride, magnesium acetate, magnesium fluoride, magnesium titanate, silicate Magnesium, magnesium silicate hydrate (talc), calcium carbonate, calcium phosphate, calcium phosphite, calcium sulfate (gypsum), calcium acetate, calcium terephthalate, calcium hydroxide, calcium silicate, calcium fluoride, calcium titanate, titanic acid Group IIA element compounds such as strontium, barium carbonate, barium phosphate, barium sulfate and barium phosphite, titanium dioxide (titania), titanium monoxide, titanium nitride, zirconium dioxide (zirconia), and zirconium oxide IVA Group element compound, molybdenum dioxide,
Group VIA element compounds such as molybdenum trioxide, molybdenum sulfide, manganese chloride, manganese acetate and the like; Group VIII element compounds such as cobalt chloride and cobalt acetate; Group IB element compounds such as cuprous iodide; Group IIB element compounds such as zinc oxide and zinc acetate; aluminum oxide (alumina); aluminum oxide; aluminum fluoride; group IIIB element compounds such as aluminosilicate (alumina silicate, kaolin, kaolinite); silicon oxide (silica, silica gel) ), Graphite, carbon, graphite, glass etc.
Particles of a group IVB element compound, natural minerals such as kernalite, kainite, mica (mica, kinmo), and virose ore. Above all, from the viewpoint of handleability,
Preferred are silica, talc, titania, alumina, calcium carbonate, calcium oxide, calcium chloride and the like, and mixtures thereof. Examples of the organic fine particles include fine particles such as cross-linked polystyrene and cross-linked polymethyl methacrylate. Antioxidants, antistatic agents, dyes, and the like can be blended with known additives for resins according to the purpose.

In the present invention, when a polymer film or a paper laminated with the polymer film is used as a support, or when a transparent support is used, in order to enhance the adhesiveness between the support and the heat-sensitive layer, these are used. It is preferable to provide an undercoat layer between the layers.

As a material for the undercoat layer, gelatin, synthetic polymer latex, nitrocellulose, acrylate copolymer, polyvinylidene chloride, styrene / butadiene rubber, aqueous polyester and the like are used. The coating amount of the undercoat layer is preferably in the range of ^{0.1g / m 2 ~2.0g / m 2} , preferably in the range particularly ^{0.2g / m 2 ~1.0g / m 2} .

The undercoat layer may be swelled by water contained in the heat-sensitive layer when the heat-sensitive layer is applied thereon, thereby deteriorating the image quality of the heat-sensitive layer. It is desirable.

As the hardener, for example, JP-A-2-141
No. 279 can be mentioned. The addition amount of these hardeners is in the range of 0.20% by weight to 3.0% by weight based on the weight of the undercoat layer, and an appropriate addition amount is selected according to the coating method and the desired degree of curing. be able to.

Depending on the hardener to be used, if necessary, caustic soda may be further added to make the pH of the solution alkaline, or the pH of the solution may be made acidic with citric acid or the like. Further, an antifoaming agent may be added to eliminate bubbles generated at the time of application, or an activator may be added to improve the leveling of the liquid and prevent the generation of coating streaks.

Further, before applying the undercoat layer, it is desirable to activate the surface of the support by a known method. As the method of the activation treatment, an etching treatment with an acid, a flame treatment with a gas burner, a corona discharge treatment, a glow discharge treatment, or the like is used. From the viewpoint of cost or simplicity, US Pat. No. 075,
Nos. 2,846,727 and 3,549,406
No. 3,590,107 and the like are most preferably used.

In the present invention, it is preferable to provide a protective layer containing a pigment on the heat-sensitive layer in order to protect the heat-sensitive layer from sticking and solvents.

Examples of such pigments include mica, talc,
Calcium carbonate, zinc oxide, titanium oxide, aluminum hydroxide, kaolin, talc, fluorite, synthetic silicate, amorphous silica, urea formalin resin powder and the like,
Among these, calcium carbonate, aluminum hydroxide, kaolin, silica, mica and talc are particularly preferred.

The protective layer in the present invention may contain aged polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silica-modified polyvinyl alcohol, etc. as a binder from the viewpoint of retaining the pigment and improving the transparency. preferable.

The coating solution for a protective layer (referred to as a protective layer solution) in the present invention is obtained by mixing a pigment with the above solution of the binder. Depending on the purpose, zinc stearate, calcium stearate, paraffin wax, polyethylene wax may be used. And various auxiliaries such as a fluorescent brightener, a crosslinking agent, a sulfosuccinic acid-based alkali metal salt and a fluorine-containing surfactant, and a polyoxyethylene surfactant.

The heat-sensitive recording material for infrared laser of the present invention comprises:
For example, an organic silver salt solid dispersion represented by the general formula RCOOAg or a microcapsule liquid containing the organic silver salt is prepared, and a developer of the organic silver salt, an infrared absorbing dye and other additives are added. Prepare a coating solution for the heat-sensitive layer, prepare a coating solution for the protective layer as described above, and apply a bar coating, blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating on the support. Coated and dried by a coating method such as that described above, a heat-sensitive layer having a solid content of 2.5 to 25 g / m ² and a solid content of 0.2 to
It is manufactured by providing a protective layer of 7 g / m ² .

The coating amount of the organic silver salt and the developer is preferably 0.5 to 3.0 g / m ² , more preferably 0.8 to 2.0 g / m ² , as the Ag component in the heat-sensitive layer. Is preferred. Further, it is desirable that the heat-sensitive layer is applied so that the thickness is 1 to 20 μm.

The coating liquid used in the present invention contains a pigment dispersant, a thickener, a flow modifier, and the like, as long as the properties of the present invention are not impaired.
An antifoaming agent, a defoaming agent, a release agent, a coloring agent, a wax, a hardener, and the like can be appropriately compounded as needed.

Further, if necessary, a back coat layer may be provided on the surface of the support of the thermosensitive recording material for infrared laser opposite to the color forming layer. As the back coat layer, any of those known as a back coat layer of a thermosensitive recording material for infrared laser can be used.

The laser beam used in the present invention has a wavelength in the near infrared region. Specific examples thereof include a helium-neon laser, an argon laser, a carbon dioxide laser, a YAG laser, and a semiconductor laser.

Next, the thermal recording method of the present invention will be described. When the infrared laser heat-sensitive recording material of the present invention is used, the absorption efficiency of the infrared laser light is high and the coloring of the background is small, so that an excellent image can be formed even with a low energy laser light, which will be described below. By applying the thermal recording method, an image having a more stable density can be formed.

The thermal recording method of the present invention is applicable to a thermosensitive recording material which develops a color at a density corresponding to the applied thermal energy.
After recording a visible image by modulating the laser beam from the heating beam generating means in accordance with the recording information and irradiating the same, the entire surface of the thermosensitive recording material is uniformly heated again at a temperature lower than the coloring temperature. The coloring reaction is promoted, and an image or the like having a stable density can be obtained. (Hereinafter, heating after recording of a visible image or the like by the laser beam is referred to as post-heat.) The post-heat temperature is set between 40 and 275 ° C. in accordance with the coloring properties of the heat-sensitive recording material. The preheating time is desirably set to 30 seconds or less from the viewpoint of throughput. More preferably, the eutectic point of the color-forming component or, when the color-forming component is microencapsulated, the temperature which is the glass transition temperature of the microcapsule wall material, etc.
The temperature is preferably set to about 0 to 150 ° C. For example, when a material having a color development temperature of 120 ° C. is used, 100 to 110 ° C.
It is preferable to heat at a temperature condition of about 0.5 to 25 seconds.

Prior to the recording of a visible image or the like (imagewise heating) by the laser beam, the entire surface of the heat-sensitive recording material is uniformly preheated at a temperature lower than the coloring temperature, and then the above-described thermal recording method is performed. For example, a sufficient dynamic range of the laser beam at the time of recording can be ensured, whereby a high gradation image or the like can be easily obtained.
(Hereinafter, preheating prior to recording of a visible image or the like by the laser beam is referred to as preheating.) As a condition of the preheating, the postheating temperature is the same as the preheating temperature (40 to 275 ° C, preferably 70 ° C).
To 150 ° C.) or less, and the heating time is likewise 30 seconds or less, preferably 10 seconds or less. Specifically, for example, when a material having a coloring temperature of 120 ° C. is used, about 0.05 to 2.5 under a temperature condition of 100 to 110 ° C.
Heating is preferably performed for about seconds, and more preferable heating time is about 0.1 second. Even if the preheating temperature does not reach the coloring temperature, long-time heating exceeding 10 seconds affects the coloring component, which is not preferable. Also,
When performing post-heating following pre-heating and visible image recording with a laser beam, the heating temperature of the post-heating is preferably equal to or lower than the temperature of the pre-heating, and the heating time of the post-heating is preferably longer than the pre-heating.

Specifically, the effect of preheating is as follows. For example, when a material having a coloring temperature of 120 ° C. is used and preheating is performed at a temperature of 110 ° C. for 0.1 second, the coloring by a laser beam is reduced by 40 mJ /. the energy of mm ² with respect to the heat-sensitive recording material was required, 4 mJ / mm ²
It was confirmed that recording could be performed with a laser beam having an energy of.

In order to perform thermal recording by adding such preheating and post-heating processes, it is preferable to use a thermal recording apparatus provided with a heating means adapted to the above method. Hereinafter, a thermal recording method to which preheating and postheating are added will be described with time using examples.

The heat-sensitive recording material is preheated (preheated) while being scanned and conveyed while being held between heat rollers. The preheating temperature just before coloring by heating of the heat roller is preheated to (hereinafter, referred to as the temperature T _1).

Next, the laser diode outputs a laser beam modulated in accordance with the gradation of the image recorded on the thermosensitive recording material, and a predetermined thermal energy is applied to the thermosensitive layer of the thermosensitive recording material by the laser beam. And a gradation image is recorded.

Here, since the heat-sensitive recording material is preheated by the heat energy given by the heat roller, the laser diode is heated from the room temperature at the place where the heat recording device is installed to the coloring temperature (hereinafter, referred to as temperature T ₂ ). need not be controlled in a wide range up referred), in this case, by controlling the laser diode at a range of temperatures T ₁ of the temperature T _2, and color at the beginning heating, a high-gradation image is formed. Further, since the laser diode does not require high output, the configuration of the entire thermal recording apparatus is simplified and the cost is low.

Next, the heat-sensitive recording material on which the gradation image is recorded is conveyed while being sandwiched between heat rollers, heated again, and subjected to post-heat treatment. That is, the thermal recording material has a temperature T just before coloring.
Heated to ₁ (same as preheat temperature). In this case, the heat-sensitive recording material which has already started developed by laser beam, color reaction is accelerated by heating to a temperature T ₁ of again, its concentration is increased to a desired value.

Therefore, for example, in order to obtain a desired density, the heat-sensitive recording material is heated by a laser beam to a predetermined temperature in consideration of the heat energy by post-heating.
What is necessary is just to perform control so that a desired density is obtained.

As described above, after the image is recorded by the laser beam, the color-forming reaction can be completed in a short time by performing the post-heat treatment for heating the thermosensitive recording material again to a temperature immediately before the color-forming. Thus, it is possible to obtain an image having a stable density over a long period without any subsequent change over time.

Further, a binder component contained in the heat-sensitive layer of the heat-sensitive recording material or a UV-curable material is selected as a wall material of the microcapsules, and an ultraviolet lamp is provided downstream of the post-heat heating section. After performing the above post heat treatment, by performing ultraviolet fixing,
The density of the image can be more reliably stabilized. That is, after the formation of a visible image necessary for color formation by the laser beam is completed, the heat-sensitive recording material is heated by the post-heat heating unit, and further, the heat-sensitive recording material is irradiated with ultraviolet light from an ultraviolet lamp to contain a coloring component. The heat-sensitive layer is cured, the subsequent reaction is suppressed, and an image having a long-term stable density without a change over time can be obtained.

As a heating means for these pre-heating and post-heating treatments, it is common to use a pair of heat rollers as described above. However, when a plurality of heat rollers are arranged in the scanning direction, The heating temperature after recording of the thermosensitive recording material can be set stably and with high accuracy. That is, by using a plurality of heat rollers, it is possible to prevent uneven heating temperature when a heat roller having a small heat capacity is used. Further, by providing a heating light source at the subsequent stage of the heat roller, and further heating the heat-sensitive recording material by the heating light source after heating by the heat roller, it is possible to prevent uneven heating temperature. Further, the same effect can be obtained by performing radiant heating with a heating light source prior to heating with a heat roller. In addition, by providing most of the energy required for heating by the post-recording heating means in the former stage, the load on the latter means can be reduced, and post-recording heating with higher precision can be performed. It should be noted that the preheating means can be similarly configured.

Examples of the heating means include radiant heating by a heating light source, heating by a heater via a thin belt, heating by absorbing infrared rays radiated from an infrared heater, and hot air heating by a hot air heater, in addition to a heat roller. Can be applied. Control of the heating time by these heating means,
It can be performed by adjusting the size of the heating means and the traveling speed of the heat-sensitive recording material.

The thermal recording apparatus used in this thermal recording method is not particularly limited, and a known recording apparatus capable of performing a desired heat treatment step can be used. For example, it is described in JP-A-6-198925. And the like can be suitably used.

Here, the heat-sensitive recording material has a characteristic that the color density increases as the preheating temperature or the heating temperature after recording increases. Therefore, the heating temperature and the heating time of the post-heat and the heating temperature and the heating time of the pre-heating performed as desired are controlled, and the output of the laser beam is considered in consideration of these conditions and the thermal energy applied to the thermosensitive recording material. And an image having desired density and gradation can be efficiently formed.

[0122]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. Unless otherwise specified in the text, "%" is "% by weight"
Means “parts” and “parts by weight”.

(Example 1) Preparation of silver behenate 25.59 g of behenic acid was added to 480 g of water, heated to 90 ° C, and an aqueous solution in which 3.0 g of NaOH was dissolved in 45 g of water was added, followed by thorough stirring. Then, it cooled to 50 degreeC.

Next, Ag was added to 75 g of water in the obtained solution.
After an aqueous solution to which 12.9 g of NO ₃ had been added was added dropwise over 5 minutes, stirring was continued for 30 minutes to cause a reaction.

The obtained reaction solution was filtered with a filter cloth, and water 800
After adding ml, stirring and washing, the mixture was filtered again. After such a washing operation was repeated three times, the obtained solid content was reduced to 5%.
It was dried for 3 days by a blow dryer at 0 ° C. to obtain a dried solid of silver behenate.

Preparation of silver behenate / phthalazone co-dispersion liquid 21.1 g was weighed from the prepared silver behenate dry solid,
To this, 3.26 g of phthalazone, 15% aqueous solution of polyvinyl alcohol (trade name: PVA205, manufactured by Kuraray Co., Ltd.)
52.8 g and 103 g of ion-exchanged water were added, and the mixture was dispersed with a paint shaker for 3 hours to obtain a behenic acid / phthalazone co-dispersion having an average particle diameter of 0.6 μm or less.

Preparation of Developer Aqueous Solution 22% polyvinyl alcohol (trade name: PVA203,
Methyl gallate 4.5 to 50.0 g (Kuraray Co., Ltd.)
g and ion-exchanged water (35.0 g) were added, and the mixture was stirred at 60 ° C. for 1 hour to prepare a developer aqueous solution.

Preparation of Coating Solution for Thermosensitive Layer 8.0 g of the above silver behenate / phthalazone co-dispersion, 4.0 g of the aqueous developer solution, 1.9 g of a 3% benzotriazole in methanol solution, and the formula (M-1) 0.12 g of the represented merocyanine compound was stirred and mixed to obtain a heat-sensitive layer coating solution.

Preparation of Coating Solution for Protective Layer 32 g of water and 10% of carboxy-modified polyvinyl alcohol (trade name: PVA-KL-318, manufactured by Kuraray Co., Ltd.)
32 g of an aqueous solution of epoxy modified polyamide (product name: F
L-71, manufactured by Toho Chemical Co., Ltd.) and a dispersion (8 g) of 30%, a 5% aqueous solution of 2% polyoxyethylene (surfactant), and a dispersion of 20% zinc stearate (trade name: Hydrin Z, 4 g of Chukyo Yushi Co., Ltd.) was added to obtain a coating liquid for a protective layer.

Preparation of Thermal Recording Material for Infrared Laser On a transparent polyethylene terephthalate support (130 μm / thickness) provided with an undercoat layer, the above-mentioned coating solution for the thermal layer was dried to a dry film thickness of 10 g / m ² using a wire bar. And dried at 50 ° C. for 20 minutes.

Next, a coating liquid for a protective layer was further applied on this coating film so that the solid content became 2.0 g / m ^2, and dried to obtain a thermosensitive recording material for infrared laser.

A 780 nm wavelength semiconductor infrared laser beam (GaAs junction laser) was irradiated imagewise from the heat-sensitive layer side of the heat-sensitive recording material for infrared laser produced as described above to obtain a black recorded image. . The output of the laser was adjusted so that an energy of 40 mJ / mm ² was obtained for 1 millisecond on the surface of the heat-sensitive layer.

The transmission density of the coloring portion of the obtained recorded image was measured using a Macbeth densitometer and found to be 2.55.

(Example 2) Preparation of capsule liquid containing silver behenate 27 g of the prepared silver behenate dry solid was weighed, and 1.10 g of polyvinyl butyral and isoamyl acetate 1 were weighed.
Add 10 g, disperse for 3 hours with a paint shaker,
Further, it is dispersed in a motor mill and has an average particle diameter of 0.4.
A μm silver behenate dispersion was obtained.

6 g of Takenate D-110N (trade name, manufactured by Takeda Pharmaceutical Co., Ltd .: isocyanate compound having the structure of the above formula (a)) as a capsule wall material in 10 g of the obtained dispersion.
Was added to obtain an oil phase component. This was added to a solution (aqueous phase) obtained by mixing 32 g of an aqueous solution of 10% polyvinyl alcohol (trade name: PVA217E, manufactured by Kuraray Co., Ltd.) and 80 g of water, and the mixture was treated with a homogenizer (Ace Homogenizer, manufactured by Nippon Seiki). The mixture was finely emulsified at 2,000 rpm for another 10 minutes.

The obtained fine emulsified dispersion was heated to 65 ° C. with stirring, and kept for 3 hours to carry out an encapsulation reaction. Here, the weight ratio of the solid content to the silver behenate of the capsule wall material was about 2.7. The obtained liquid is a microcapsule liquid containing silver behenate and having an average particle size of 0.8 μm.

Preparation of Coating Solution 4 g of water was added to 15 g of the capsule solution containing silver behenate.
A coating solution was obtained by mixing 0.6 g of a 3% benzotriazole methanol solution, 2.8 g of the developer aqueous solution, and 0.4 g of the merocyanine compound represented by the formula (M-3).

Preparation of Thermal Recording Material for Infrared Laser In the same manner as in Example 1, the coating liquid was dried in a film thickness of 20 g.
/ M ^2, and then a protective layer is applied on the coating film to a dry film thickness of 2.0 g / m ² and dried. I got

The infrared recording layer for infrared laser produced as described above was irradiated imagewise with a semiconductor infrared laser beam (GaAs junction laser) having a wavelength of 780 nm from the thermosensitive layer side to obtain a black recorded image. . The output of the laser was adjusted so that an energy of 40 mJ / mm ² was obtained for 1 millisecond on the surface of the heat-sensitive layer.

The transmission density of the coloring portion of the obtained recorded image was measured using a Macbeth densitometer, and was found to be 2.50. The thermal recording material for an infrared laser of Example 2
After storage at 40 ° C. 90% RH for 1 day, and at 60 ° C. 30
Observation of background fog after storage at 1% RH for 1 day confirmed that it was superior to that of Example 1.

Example 3 Instead of the merocyanine compound (M-1) used in Example 1, the compound of the formula (M-
A thermosensitive recording material for infrared laser was produced in exactly the same manner as in Example 1 except that the merocyanine compound represented by 7) was used.

The obtained thermosensitive recording material for infrared laser was
Semiconductor infrared laser light (GaAs junction laser) having a wavelength of 780 nm was imagewise irradiated from the heat-sensitive layer side to obtain a black recorded image. The output of the laser beam was 40 mJ per millisecond on the surface of the thermosensitive layer of the thermosensitive recording material for infrared laser.
/ Mm ² .

The transmission density of the obtained black recorded image was measured by a Macbeth densitometer and found to be 2.53.

Example 4 Instead of the merocyanine compound (M-1) used in Example 1, the compound of the formula (M-
A thermosensitive recording material for infrared laser was produced in exactly the same manner as in Example 1 except that the merocyanine compound represented by 5) was used.

The obtained heat-sensitive recording material for infrared laser was
Semiconductor infrared laser light (GaAs junction laser) having a wavelength of 780 nm was imagewise irradiated from the heat-sensitive layer side to obtain a black recorded image. The output of the laser beam was 40 mJ per millisecond on the surface of the thermosensitive layer of the thermosensitive recording material for infrared laser.
/ Mm ² .

The transmission density of the obtained black recorded image was 2.58 as measured by a Macbeth densitometer.

(Example 5) In the same manner as in Example 1, a semiconductor infrared laser light (G
aAs bonding laser) was irradiated imagewise from the heat-sensitive layer side. Thereafter, the heat-sensitive recording material for infrared laser was
C. and maintained at that temperature for 2.0 seconds to obtain a black recorded image.

The transmission density of the obtained black recorded image was 3.20 as measured by a Macbeth densitometer.

Example 6 The thermosensitive recording material for infrared laser prepared in Example 1 was heated to a temperature of 110 ° C.
After holding for 0.1 second, in the same manner as in Example 1, a semiconductor infrared laser beam (GaAs
(Bonding laser) was irradiated imagewise from the heat-sensitive layer side. The output of the laser beam was adjusted so that the energy of 4 mJ / mm ² was obtained for 1 millisecond on the surface of the heat-sensitive layer of the heat-sensitive recording material for infrared laser.

The transmission density of the obtained black recorded image was 3.64 as measured by a Macbeth densitometer.

(Example 7) The thermosensitive recording material for infrared laser prepared in Example 1 was heated to a temperature of 110 ° C.
After holding for 0.1 second, the semiconductor infrared laser light (GaAs
(Bonding laser) was irradiated imagewise from the heat-sensitive layer side. Thereafter, the thermosensitive recording material for an infrared laser was heated to 106 ° C. and kept at that temperature for 2.0 seconds to obtain a black recorded image. The output of the laser beam was adjusted so that the energy of 4 mJ / mm ² was obtained for 1 millisecond on the surface of the heat-sensitive layer of the heat-sensitive recording material for infrared laser.

The transmission density of the obtained black recorded image was measured by a Macbeth densitometer to be 3.30.

(Comparative Example 1) A thermosensitive recording material for infrared laser was prepared and an image was recorded in the same manner as in Example 1 except that the merocyanine compound used in Example 1 was not used, and an image was recorded. I couldn't.

Comparative Example 2 A heat-sensitive recording material for infrared laser was prepared in exactly the same manner as in Example 1 except that a carbon black dispersion was used as an infrared absorbing dye instead of the merocyanine compound used in Example 1. An image was recorded, and the transmission density was measured. The transmission density of the color-developed portion of the obtained recorded image was 1.24 (Macbeth densitometer). Further, it was visually observed that coloring of the background portion was large.

Comparative Example 3 A heat-sensitive recording material for infrared laser was prepared in exactly the same manner as in Example 2 except that an infrared absorbing dye represented by the following formula was used instead of the merocyanine compound used in Example 2. Then, the image was recorded. When the transmission density of the image was measured, the transmission density of the coloring portion of the obtained recorded image was 0.80 (Macbeth densitometer). Also,
It was visually observed that coloring of the background portion was large.

[0156]

Embedded image

Comparative Example 4 A thermosensitive recording material for infrared laser was produced in the same manner as in Example 2 except that an infrared absorbing dye represented by the following formula was used instead of the merocyanine compound used in Example 2. Then, an image was recorded and its transmission density was measured. As a result, the transmission density of the coloring portion of the obtained recorded image was 1.57 (Macbeth densitometer). Further, it was observed that the coloring of the background portion was slightly noticeable by visual observation.

[0158]

Embedded image

The transmission densities (by a Macbeth densitometer) of the colored portions of the recorded images obtained in Examples 1 to 7 and Comparative Examples 1 to 4, coloring of the background and heat-sensitive recording materials were measured at 40 ° C. 9
Table 1 shows the results of evaluating fog change and concentration change when stored at 0% RH for 3 days according to the following criteria. (Evaluation criteria) Image recording sensitivity （(extremely high sensitivity): transmission density of the recorded image is 3.0 or more 〇 (high sensitivity): transmission density of 2.0 or more and less than 3.0 Δ〜 (low sensitivity): transmission density 2 Coloring of background less than 0 Δ: Observed visually, little coloration and no practical problem Δ: Observed visually, slightly discolored ×: Observed visually, large raw preservability (fog) (Amount of change) The thermosensitive recording material was stored at 40 ° C. and 90% RH for 3 days before recording, and then the image was recorded. The fog of the thermosensitive recording material which had not been subjected to the storage test was recorded under the same conditions. The change in concentration was measured. Those having a variation of ± 0.02 or less were evaluated as acceptable levels.

After image recording , the image was recorded at 40 ° C. 9
It was stored at 0% RH for 3 days, and the density change of the background before and after storage was measured. Those having a variation of ± 0.05 or less were evaluated as acceptable levels.

[0161]

[Table 1]

As shown in Table 1, all the images obtained in Examples 1 to 7 have higher transmission densities than the images obtained in Comparative Examples 2 to 4, in other words, recording with good coloring. It can be seen that an image was obtained and the degree of coloring of the background was thinner and better than Comparative Examples 2 to 4. That is, it can be seen that in this embodiment, a recorded image with high contrast can be obtained. In addition, from a comparison between Example 2 and Comparative Example 3 and Comparative Example 4 that differ only in the used infrared absorbing dye, it can be seen that the above-mentioned effect is attributable to the use of the merocyanine compound as the infrared absorbing dye.

Further, from the comparison between Example 1 and Examples 5 to 7, it was found that the same heat-sensitive recording material was obtained by applying the heat recording method of the present invention in which post-heat treatment and / or pre-heat treatment was performed before and after image recording by laser. It can be seen that even with the use of, high-sensitivity image recording and good image recording using a laser with lower energy can be performed.

[0164]

The heat-sensitive recording material for infrared laser of the present invention has the effect of high absorption efficiency of infrared laser light, less coloring of the background, and high quality recording. Further, when at least one of the organic silver salt and the organic silver salt developer is microencapsulated, fogging over time can be further reduced.

Further, according to the thermal recording method of the present invention, it is possible to stabilize the density of an image after recording by using the above-mentioned thermosensitive recording material for an infrared laser, and to use a laser for recording an image or the like. A high-gradation, high-precision image or the like can be obtained by sufficiently securing the dynamic range of the beam, and the load on the heating beam generating means for generating the laser beam is reduced to make the apparatus simple and inexpensive. It can be.

Claims (7)

[Claims] 1. An organic silver salt, an organic silver salt,
Silver salt developer, infrared absorbing dye, and water-soluble binder
A heat-sensitive recording material provided with a heat-sensitive layer, comprising:
Infrared laser feeling characterized by being an anine compound
Thermal recording material. Embedded image(Wherein, R represents a substituted or unsubstituted alkyl having 1 to 6 carbon atoms)
A substituted or unsubstituted alkyl group having 5 to 10 carbon atoms.
Reel or hetaryl, R¹, R ^Two, R
^ThreeAnd R^FourAre each independently a hydrogen atom, a halogen atom,
Ano group, alkoxy group, aryloxy group, arylo
Xycarbonyl group, alkoxycarbonyl group, alkyl
Sulfonyl group, arylsulfonyl group, carbamoyl
Group, acyl group, acylamide group, alkylamino group,
Reelamino group, substituted or unsubstituted alkyl group, aryl
Or a hetaryl group, or R, R¹,
R^Two, R^ThreeAnd R^FourTwo of which are bonded to each other and
Forms an unsubstituted 5- to 7-membered aliphatic or heterocyclic ring
A is -COR, -CO_TwoR, -CONHR,-
CONR_Two, -SO_TwoR, -SO_TwoNHR, -SO_TwoN
R_Two, -SR or -CN, B is -NHR,-
NR_Two, -OR, -SR, or R, or A
And B are bonded to each other or R^ThreeOr R^FourCombined with
Forming a substituted or unsubstituted 5- to 7-membered aliphatic or heterocyclic ring;
You may. Y is a dialkyl group-substituted carbon atom, vinylene,
Oxygen atom, sulfur atom, selenium atom, tellurium atom or -N
R- and Z forms a 5- to 7-membered aliphatic or heterocyclic ring
N is an integer of 3 to 5. ) 2. The thermosensitive recording material for infrared laser according to claim 1, wherein the organic silver salt is contained in a solid dispersion state. 3. The thermosensitive recording material for an infrared laser according to claim 1, wherein at least one of the organic silver salt and a developer of the organic silver salt is microencapsulated. 4. The heat-sensitive recording material for infrared laser light according to claim 1, further comprising a development accelerator for the organic silver salt. 5. A method according to claim 1, wherein at least an organic silver salt, a developer of an organic silver salt, and an infrared-absorbing dye are represented by the general formula (I) on a support.
In the heat-sensitive recording material, which is provided with a heat-sensitive layer containing a merocyanine compound represented by the formula and a water-soluble binder, and develops a color at a concentration corresponding to the applied heat energy, an infrared light modulated according to the recording information. A first step of irradiating a laser beam to imagewise heat the thermosensitive recording material to a predetermined coloring temperature; and A second step of heating uniformly at a temperature; and a heat recording method. 6. On a support, at least an organic silver salt, a developer of an organic silver salt, and an infrared absorbing dye represented by the general formula (I)
Is provided with a heat-sensitive layer containing a merocyanine compound represented by the formula (1) and a water-soluble binder, and uniformly heats the entire surface of the heat-sensitive recording material that develops color at a concentration corresponding to the applied heat energy to a predetermined temperature lower than the coloration temperature. A first process, and irradiating the preheated thermosensitive recording material with an infrared laser beam modulated in accordance with recording information, and imagewise heating the thermosensitive recording material to a predetermined coloring temperature. And a thermal recording method comprising: 7. On a support, at least an organic silver salt, a developer of an organic silver salt, and an infrared absorbing dye represented by the general formula (I)
Is provided with a heat-sensitive layer containing a merocyanine compound represented by the formula (1) and a water-soluble binder, and uniformly heats the entire surface of the heat-sensitive recording material that develops color at a concentration corresponding to the applied heat energy to a predetermined temperature lower than the coloration temperature. A first process, and irradiating the preheated thermosensitive recording material with an infrared laser beam modulated in accordance with recording information, and imagewise heating the thermosensitive recording material to a predetermined coloring temperature. And a third step of uniformly heating the entire surface of the image-wise heated heat-sensitive recording material at a predetermined temperature lower than the coloring temperature of the heat-sensitive recording material.