JPH0717138A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording layer forming an image excellent in light fastness by adding a hydrophobic guanidine derivative and a hydrophobic piperazine derivative to the thermal recording layer containing a coupler as a main component on a support. CONSTITUTION:A thermal recording material is formed by providing at least one thermal recording layer containing a diazo compd. and a coupler reacting with the diazo compd. to develop a color as main components on a support and adding at least one kind of a hydrophobic guanidine derivative and one kind of a hydrophobic piperazine derivative to the thermal recording material. The coupler among the color forming components is pref. present in the same emulsion as the hydrophobic guanidine derivative and the hydrophobic piperazine derivative and the diazo compd. can be allowed to be present in the same emulsion as both derivatives. In order to further improve light fastness, a protective layer can be provided on the thermal color forming layer.

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 heat-sensitive recording material excellent in light fastness of an image.

[0002]

2. Description of the Related Art A heat-sensitive recording method has made remarkable progress in recent years and has been applied to various purposes because it is highly reliable and requires no maintenance despite the fact that the recording apparatus used is simple. Reproduction of multicolor images is more difficult than electrophotographic recording methods and inkjet methods. A thermosensitive coloring layer containing an electron-donating dye precursor and an electron-accepting compound as a main component on a support and / or a diazo compound and the diazo compound when heated to reproduce a multicolor image by a heat-sensitive recording method. A multicolor thermosensitive recording material comprising one or more thermosensitive color developing layers containing a coupler which reacts to develop color is known.

However, the images of known multicolor heat-sensitive recording materials are significantly inferior in light fastness to the images obtained by other methods (electrophotographic recording method and ink jet method).
Therefore, it is required to improve the light fastness of the image of the multicolor thermosensitive recording material. In addition, hydrophobic guanidine derivatives and piperazine derivatives are known as basic compounds that promote diazo coupling. They are, for example, JP-A-57-123086 and JP-A-60-49991.
No. 2, Japanese Patent Publication No. 2-28479, Japanese Patent Publication No. 3-24915
No. 2, Japanese Patent Publication No. 24916/1990. However, there is no known example in which they are used in combination, and the effect of these compounds on the light fastness of the dye formed by coupling is not described.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material excellent in light fastness of an image using a heat-sensitive recording layer containing a diazo compound and a coupler which reacts with the diazo compound to develop a color. To do.

[0005]

The above objects of the present invention are as follows.
In a heat-sensitive recording material having at least one heat-sensitive recording layer containing as a main component a diazo compound and a coupler which reacts with the diazo compound to form a color on a support, the heat-sensitive recording layer contains a hydrophobic guanidine derivative and a piperazine derivative. This is achieved by a thermosensitive recording material characterized by containing at least one kind of each.

That is, in the present invention, the light fastness of the azo dye produced by the diazo coupling between the diazo compound and the coupler is improved by using the hydrophobic guanidine derivative and the piperazine derivative in combination. This is an unprecedented new finding. Furthermore, in the present invention, it is preferable that at least one of the color-forming components is encapsulated in microcapsules.

Further, in the present invention, it is preferable that the coupler among the color-forming components is in the same emulsion as the hydrophobic guanidine derivative and the piperazine derivative. Further, the diazo compound can be present in the same emulsion as the hydrophobic guanidine derivative and the piperidine derivative.

The hydrophobic guanidine derivative of the present invention can be represented by the following general formula [I].

[0009]

[Chemical 1]

Typical examples of the hydrophobic guanidine derivative of the present invention are shown below, but the compounds used in the present invention are not limited thereto.

[0011]

[Chemical 2]

[0012]

[Chemical 3]

[0013]

[Chemical 4]

[0014]

[Chemical 5]

[0015]

[Chemical 6]

[0016]

[Chemical 7]

[0017]

[Chemical 8]

[0018]

[Chemical 9]

[0019]

[Chemical 10]

The hydrophobic guanidine derivative of the present invention can be easily synthesized by a known method or a method similar thereto.

The piperazine derivative of the present invention will be described in detail. The piperazine derivative of the present invention may be any one as long as it has a piperazine ring, but a compound having a total carbon number of 8 or more is preferable, and a compound having 12 or more is particularly preferable. Preferred piperazine derivatives include those represented by the following general formula [B].

[0022]

[Chemical 11]

In the formula, R and R'may be the same or different and each represents a hydrogen atom, an alkyl group, an alkenyl group,
It represents an aryl group, a heterocyclic group, an acyl group or a sulfonyl group. R ₀ represents a substituent, and n represents an integer of 0-8. When n is 2 to 8, a plurality of R ₀ may be the same or different.

Among the compounds represented by the general formula [B],
When R and R'are an alkyl group and the alkyl group has a substituent, those having a substituent at the β-position and after of the alkyl group are preferable. It is preferable that R and R ′ are selected from a hydrogen atom, an alkyl group and an alkenyl group,
The case where it is selected from an alkyl group and an alkenyl group is particularly preferable.

R ₀ represents a substituent, for example, an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, an alkoxy group, an alkenyloxy group, an aryloxy group, a heterocyclic oxy group, an alkylthio group, an alkenylthio group, an arylthio group. , Heterocyclic thio group, amino group, acylamino group, sulfonamide group, alkylamino group, arylamino group, heterocyclic amino group, alkyloxycarbonyl group, aryloxycarbonyl group, halogen atom, acyl group, sulfonyl group, carbamoyl group , Sulfamoyl group, cyano group, nitro group, hydroxy group, sulfo group or carboxyl group. Of these, R ₀ is preferably an alkyl group. On the other hand, n is preferably 0 to 4, more preferably 0 to 2, and most preferably n is 0.

R, R'and R ₀ may further have a substituent, and examples of the substituent include the groups mentioned for R ₀ . However, when R and R ′ are alkyl groups, those having a substituent at the β-position or later of the alkyl group are preferable. More preferably, it is an unsubstituted alkyl group.

Representative examples of the piperazine derivative of the present invention are shown below, but the compounds used in the present invention are not limited thereto.

[0028]

[Chemical 12]

[0029]

[Chemical 13]

[0030]

[Chemical 14]

[0031]

[Chemical 15]

[0032]

[Chemical 16]

[0033]

[Chemical 17]

The piperazine derivative of the present invention can be easily synthesized by a known method or a method similar thereto.

The amounts of the hydrophobic guanidine derivative and the piperazine derivative added are each 10 to 1000 mol%, preferably 40 to 400 mol% based on the coupler used.
Is. Furthermore, they dissolve in high-boiling organic compounds,
It is preferably used as an emulsion with suitable protective colloids. More preferably, it is used by coemulsifying with a coupler.

The amount of the piperazine derivative added is 10 to 1000 mol%, more preferably 30 to 300 mol%, based on the hydrophobic guanidine derivative.

The other components used in the present invention will be described below. The heat-sensitive color forming layer of the present invention contains a diazo compound and a coupler that reacts with the diazo compound when heated to develop a color. As the diazo compound, a known photodegradable diazo compound is used, and further, there are a coupler capable of reacting with the diazo compound to form a dye, and a basic substance accelerating the reaction between the diazo compound and the coupler. The photodecomposable diazo compound referred to in the present invention mainly refers to an aromatic diazo compound, and more specifically, an aromatic diazonium salt,
It means a diazosulfonate compound, a diazoamino compound and the like. Among these, it is particularly preferable to use a diazonium salt from the viewpoint of thermal sensitivity.

The present invention in a preferred formula Ar-N ₂ ⁺ X The diazonium salt ^- (wherein Ar represents an aromatic moiety, X ^- represents an acid anion) is a compound represented by the. These have various maximum light absorption wavelengths depending on the position and type of the substituent of the Ar portion.

Specific examples of the diazo compound used in the present invention include 4- (N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzenediazonium, 4-dioctylaminobenzenediazonium,
4- (N- (2-ethylhexanoyl) piperazino) benzenediazonium, 4-dihexylamino-2-hexyloxybenzenediazonium, 4-N-ethyl-N
-Hexadecylamino-2-ethoxybenzodiazonium, 3-chloro-4-dioctylamino-2-octyloxybenzenediazonium, 2,5-dibutoxy-4
-Morpholinobenzenediazonium, 2,5-octoxy-4-morpholinobenzenediazonium, 2,5-dibutoxy-4- (N- (2-ethylhexanoyl) piperazino) benzenediazonium, 2,5-diethoxy-
4- (N- (2- (2,4-di-tert-amylphenoxy) butyryl) piperazino) benzenediazonium,
2,5-dibutoxy-4-tolylthiobenzenediazonium, 3- (2-octyloxyethoxy) -4-morpholinobenzenediazonium and the like can be mentioned.

In the present invention, these hexafluorophosphate salts, tetrafluoroborate salts,
1,5-naphthalene sulfonate salt has low water solubility,
It is useful because it is soluble in organic solvents.

Examples of couplers which develop color upon thermal reaction with the diazo compound used in the present invention include resorcin, phloroglucin, sodium 2,3-dihydroxynaphthalene-6-sulfonate and morpholinopropyl 1-hydroxy-2-naphthoate. Amide, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-dihydroxy-6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid anilide, 2-hydroxy-3-
Naphthoic acid ethanolamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid-N-dodecyloxypropylamide, 2-hydroxy-3-naphthoic acid tetradecylamide, acetanilide, acetoacetanilide, benzoyl Acetanilide, 2-chloro-5-octylacetoacetanilide,
1- (2-tetradecanooxyphenyl) -2-carboxymethylcyclohexane-3,5-dione, 1-phenyl-3-methyl-5-pyrazolone, 1- (2'-octylphenyl) -3-methyl- 5-pyrazolone, 1-
(2 ', 4', 6'-Trichlorophenyl) -3-benzamido-5-pyrazolone, 1- (2 ', 4', 6'-
Trichlorophenyl) -3-anilino-5-pyrazolone, 1-phenyl-3-phenylacetamido-5-pyrazolone and the like can be mentioned. Two or more of these couplers may be used in combination.

Further, the heat-sensitive recording material of the present invention comprises, in addition to the heat-sensitive recording layer containing the diazo compound of the present invention and a coupler and a hydrophobic guanidine derivative and a piperidine derivative, an electron-donating dye precursor and an electron-accepting layer. A heat-sensitive recording layer containing a photosensitive compound can be further provided. Further, by providing a plurality of thermosensitive recording layers in this way, a multicolor thermosensitive recording material can be obtained. As a known raw material used for a heat-sensitive recording layer containing an electron-donating dye precursor and an electron-accepting compound as main components, an electron-donating dye precursor and an electron-accepting compound react with each other when heated. There are low-melting-point organic compounds and the like that help.

Examples of the electron-donating dye precursor include triarylmethane compounds, diphenylmethane compounds, thiazine compounds, xanthene compounds, spiropyran compounds, and the like, but triarylmethane compounds and xanthene compounds are particularly preferable. It is useful because the color density is high.

Specific examples of these include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (that is, crystal violet lactone),
3,3-bis (p-dimethylamino) phthalide, 3-
(P-Dimethylaminophenyl) -3- (1,3-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindole-
3-yl) phthalide, 3- (o-methyl-p-dimethylaminophenyl) -3- (2-methylindole-3-
Yl) phthalide, 4,4′-bis (dimethylamino) benzhydrin benzyl ether, N-halophenyl leuco auramine, N-2,4,5-trichlorophenyl leuco auramine, rhodamine-B-anilinolactam,
Rhodamine (p-nitroanilino) lactam, Rhodamine-B- (p-chloroanilino) lactam, 2-benzylamino-6-diethylaminofluorane, 2-anilino-6-diethylaminofluorane, 2-anilino-3
-Methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-cyclohexylmethylaminofluorane, 2-anilino-3-methyl-6-isoamylethylaminofluorane, 2- (o-chloroanilino)-
6-diethylaminofluorane, 2-octylamino-
6-diethylaminofluorane, 2-ethoxyethylamino-3-chloro-2-diethylaminofluorane, 2
-Anilino-3-chloro-6-diethylaminofluorane, benzoylleuco methylene blue, p-nitrobenzyl leuco methylene blue, 3-methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran,
3,3'-dichloro-spiro-dinaphthopyran, 3-benzylspirodinaphthopyran, 3-propyl-spiro-
There are dibenzopyran and the like.

Examples of the electron accepting compound include phenol derivatives, salicylic acid derivatives, hydroxybenzoic acid esters and the like. Among these, bisphenols and hydroxybenzoic acid esters are particularly preferable. Examples of some of these include 2,2-bis (p-hydroxyphenyl) propane (ie, bisphenol A), 2,2
-Bis (p-hydroxyphenyl) pentane, 2,2-
Bis (p-hydroxyphenyl) ethane, 2,2-bis (p-hydroxyphenyl) butane, 2,2-bis (4'-hydroxy-3 ', 5'-dichlorophenyl)
Propane, 1,1- (p-hydroxyphenyl) cyclohexane, 1,1- (p-hydroxyphenyl) propane, 1,1- (p-hydroxyphenyl) pentane,
1,1- (p-hydroxyphenyl) -2-ethylhexane, 3,5-di (α-methylbenzyl) salicylic acid and its polyvalent metal salt, 3,5-di (tert-butyl) salicylic acid and its polyvalent Metal salts, 3-α, α-dimethylbenzyl salicylic acid and polyvalent metal salts thereof, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, 2-ethylhexyl p-hydroxybenzoate, p-phenylphenol, p- Examples include cumylphenol.

A sensitizer for promoting the reaction is preferably added to the heat-sensitive recording layer composed of the electron-donating dye precursor and the electron-accepting compound. As the sensitizer, a low melting point organic compound having an aromatic group and a polar group in the molecule is preferable, and specific examples thereof include benzyl p-benzyloxybenzoate, α-naphthylbenzyl ether, β-naphthylbenzyl ether, β-naphthoic acid phenyl ester, α-hydroxy-β-naphthoic acid phenyl ester, β-naphthol- (p-chlorobenzyl) ether, 1,4-butanediol phenyl ether, 1,4-butane Diol-p-methylphenyl ether, 1,4-butanediol-p-ethylphenyl ether, 1,4-butanediol-m-methylphenyl ether, 1-phenoxy-2- (p-tolyloxy)
Examples thereof include ethane, 1-phenoxy-2- (p-ethylphenoxy) ethane, 1-phenoxy-2- (p-chlorophenoxy) ethane and p-benzylbiphenyl.

In order to dissolve the coloring components or additives,
A high-boiling point organic solvent used as a dispersion solvent for a color material (coupler, dye-donor compound, etc.) of an ordinary color light-sensitive material can be used. Examples of the high boiling point organic solvent include alkyl phthalates (eg, dibutyl phthalate, dioctyl phthalate, etc.), phosphoric acid esters (eg, diphenyl phosphate, triphenyl phosphate, etc.), citric acid esters (eg, tributyl acetyl citrate), benzoic acid. Acid esters (eg, octyl benzoate), alkylamides (eg, diethyllaurylamide), aliphatic esters (eg, dibutoxyethyl succinate), trimesic acid esters (eg, tributyl trimesate), JP-A-63-85633. Carboxylic acids described in JP-A-59-83154 and 59-1.
78451-178455, 59-178457.
The compounds described in each publication.

In the present invention, a protective layer may be provided on the thermosensitive coloring layer in order to further improve light fastness. Further, in the multicolor thermosensitive material, an intermediate layer may be provided between the thermosensitive recording layers in order to further improve the heat fractionation property. The material of the layer used for these is preferably an emulsion or latex of a water-soluble polymer compound or a hydrophobic polymer compound.

Examples of the water-soluble polymer compound include polyvinyl alcohol, silanol-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, styrene-maleic anhydride copolymer and its ester, butadiene-maleic anhydride copolymer, ethylene-maleic anhydride. Copolymer, isobutylene-maleic anhydride copolymer, polyacrylamide, polystyrene sulfonic acid, polyvinylpyrrolidone, ethylene-acrylic acid copolymer, vinyl acetate-
Acrylic acid copolymer, oxidized starch, phosphorylated starch,
Examples thereof include gelatin, carboxymethyl cellulose, methyl cellulose, sodium alginate, sulfated cellulose, hydroxyethyl cellulose and the like.

Examples of the emulsion or latex of the hydrophobic polymer compound include styrene-butadiene copolymer, carboxy-modified styrene-butadiene copolymer, acrylonitrile-butadiene copolymer and the like.

Next, a method for producing the heat-sensitive recording material will be described.
In the heat-sensitive recording material of the present invention, a single layer using one of the heat-sensitive recording layers comprising a diazo compound and a coupler, and two or more of these layers or in addition to this layer, an electron donating dye precursor and an electron There are cases where one or more heat-sensitive recording layers composed of an acceptor compound are used to form a plurality of layers, and all of the heat-sensitive recording layers of one layer or a plurality of layers are colored components thereof, that is, an electron-donating dye precursor and an electron-accepting compound. Alternatively, the diazo compound and the coupler need to be uniformly dispersed in the binder and held in the recording layer so as not to come into contact with each other before heating.

Specific examples of the binder include polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin,
Examples thereof include styrene / acrylic acid copolymers.

As a specific method, each material is separately dispersed in an aqueous solution of a water-soluble polymer compound (for example, polyvinyl alcohol), and the water-soluble polymer compound is sufficiently adsorbed on the surface of each material and then mixed. A method, a method of microencapsulating at least one of the components,
There is a method of separating the reaction components layer by layer, and a method of microencapsulating one of the color-forming components is particularly preferable.

The electron-donating dye precursor and the electron-accepting compound are described below as examples, but the same applies to the case of the diazo compound and the coupler. In the above method, an electron-donating dye precursor (for example, crystal violet lactone) is put into an aqueous solution of a water-soluble polymer compound (for example, polyvinyl alcohol) and dispersed by means of a ball mill or the like. In this operation, the crystal of the electron-donating dye precursor is pulverized into fine particles, and at the same time, the water-soluble polymer compound is adsorbed on the surface of the crystal, and the electron-donating dye is protected by the adsorption layer of the water-soluble polymer compound. A fine particle dispersion of the precursor is obtained. Similarly, a fine particle dispersion of an electron accepting compound (for example, bisphenol A) can be obtained. Even if both dispersions thus obtained are mixed, no color-forming reaction occurs because each color-forming component is protected by the water-soluble polymer compound adsorption layer. Therefore, a recording material can be obtained by applying this mixed liquid onto a support. However, when heated for recording, at least one of the color-forming components melts, breaks the adsorption layer and diffuses, and as a result, both color-forming components come into contact with each other, so that a color-forming reaction occurs and a colored image is obtained.

As the water-soluble polymer compound used in the above-mentioned method, the water-soluble polymer compound used in the above-mentioned intermediate layer can be used, and especially polyvinyl alcohol and its derivatives, polyacrylamide and its copolymers. , Hydroxyethyl cellulose, starch derivatives and the like are preferable.

In the method of microencapsulating at least one of the components, the electron-donating colorless dye and / or the electron-accepting compound may be encapsulated by a conventional method.

The microcapsules used in the present invention are
It is a thermo-responsive microcapsule that has the property of strictly isolating the substance inside the capsule from the substance outside the capsule at room temperature, and at the same time can accelerate the reaction of the coloring component by increasing the permeability of the wall when heated. Need to be

As the wall material of the capsule, gelatin, polyurea, polyurethane, polyimide, polyester, polycarbonate, melamine and the like can be used, but polyurea or polyurethane is preferably used from the viewpoint of obtaining thermoresponsive microcapsules. Further, in order to impart thermal responsiveness to the capsule wall, the glass transition point of the capsule wall may be room temperature to 200 ° C., particularly 70 ° C.
It is preferably in the range of 150 ° C.

The glass transition temperature of the capsule wall can be controlled by selecting the polymer species of the capsule wall or adding an appropriate plasticizer. Examples of such a plasticizer include a phenol compound, an alcohol compound, an amide compound, a sulfonamide compound, and the like, which may be contained in the core material of the capsule or added as a dispersion outside the microcapsule. .

Specific examples of the microencapsulation method, materials and compounds to be used are described in, for example, US Pat. No. 37.
No. 26804 and No. 3796696. The method of microencapsulating the electron-donating dye precursor will be described below, but the same applies to the case of microencapsulating other materials.

For example, when polyurethane or polyurea is used as the capsule wall material, the polyisocyanate and the second substance (eg, polyol or polyamine) which reacts with the polyisocyanate to form the capsule wall are used as an aqueous phase or an oily substance to be encapsulated. After mixing in a liquid to form a core composition, the core composition is emulsified and dispersed in water, and then the temperature is raised to cause a polymer forming reaction at the oil drop interface to form a microcapsule wall. In this case, the glass transition point of the capsule wall can be significantly changed by appropriately selecting the polyvalent isocyanate as the first wall film forming substance and the polyol or polyamine as the second wall film forming substance.

Further, a low-boiling auxiliary solvent may be added in order to assist the dissolution of the electron-donating dye precursor. Specific examples of the auxiliary solvent include ethyl acetate, isopropyl acetate, butyl acetate, methylene chloride, cyclohexanone and the like. Further, a protective colloid or a surfactant can be added to the aqueous phase in order to stably produce emulsified oil droplets.

As the protective colloid, water-soluble polymer compounds can be generally used, and specific examples thereof include polyvinyl alcohol, modified polyvinyl alcohol, methyl cellulose, sodium polystyrene sulfonate,
Examples thereof include ethylene / maleic acid copolymers.

The size of the microcapsules is 0.2 μm in volume average, especially from the viewpoint of improving image resolution and handling.
m to 20 μm is preferable, and more preferably 0.4 μm to
It is 4 μm.

Since the separating action of the material by the microcapsule wall is generally more complete than the separating action of the material by the adsorption layer of the water-soluble polymer compound, it is sufficient to microencapsulate either one of the reaction components. The contact between each other can be suppressed. Therefore, for example, when the electron-donating dye precursor is microencapsulated, the electron-accepting compound can be mixed with the capsule liquid as a dispersion in which the electron-accepting compound is simply dispersed in fine particles. However, it is also possible to dissolve the electron-accepting compound in a high boiling point solvent, emulsify it in an aqueous solution of a water-soluble polymer, and then mix with the capsule liquid.

In the latter case, there is an advantage that a transparent thermosensitive recording layer can be obtained by applying a coating solution on a support and drying it. Therefore, in this case, a transparent thermosensitive recording material can be obtained by using a transparent support such as a plastic base as the support.

As the support used in the heat-sensitive recording material of the present invention, known materials such as paper, laminated paper in which polyethylene or the like is laminated on paper, synthetic paper, polyethylene terephthalate, polyimide, plastic film such as triacetyl cellulose are used. To be done. Further, these supports may be undercoated to improve the adhesion with the coating layer.

As a method for coating the support, an air knife coating method, a curtain coating method, a slide coating method,
Examples of the method include, but are not limited to, a roller coating method, a dip coating method, a wire bar coating method, a blade coating method, a gravure coating method, a spin coating method and an extrusion coating method. By these methods, the thermosensitive recording material of the present invention can be obtained by successively coating each thermosensitive recording layer on the support. If necessary, a protective layer may be provided on the heat sensitive layer as described above.

When recording on this recording material, first, heat is applied so that the thermosensitive recording layer develops color, and after the color is developed, the entire surface of the recording material is irradiated with light to decompose the diazonium salt contained in the thermosensitive layer. To do. Next, a recording method of the multicolor thermosensitive recording material will be described. First, the outermost heat-sensitive layer (first heat-sensitive recording layer) containing the diazo compound is colored by heat recording with low heat energy, and then light in the absorption wavelength range of the diazo compound contained in the heat-sensitive layer is emitted. The entire surface is irradiated with light using a light source to photolyze the diazo compound remaining in the uppermost heat-sensitive layer.

Then, the second heat-sensitive layer (the second layer) containing a diazo compound having a higher energy than the previous time and having a light absorption wavelength band different from the light of the absorption wavelength band of the diazo compound contained in the first layer (the first layer). (2) Thermosensitive recording layer), and then the whole surface is irradiated again with a light source that emits light in the absorption wavelength range of the diazo compound, whereby the diazo compound remaining in the second heating layer is exposed to light. Disassemble. Finally, with higher energy, the innermost layer (third heat-sensitive recording layer) of the layer containing the electron-donating dye precursor is colored to complete the image recording.

In the above case, it is preferable that the outermost layer and the second layer are transparent heat-sensitive layers because each color becomes vivid.

In the present invention, a multi-color image can be obtained by using a transparent support as the support and coating any one of the above three layers on the back surface of the transparent support. In this case, the uppermost heat-sensitive layer on the side opposite to the image viewing side does not need to be transparent.

An ultraviolet lamp is usually used as the light source used for the photolysis of the diazo compound. An ultraviolet lamp is a fluorescent tube in which mercury vapor is filled in the tube, and fluorescent tubes having various emission wavelengths can be obtained depending on the type of fluorescent material applied to the inner wall of the tube.

[0074]

EXAMPLES Examples will be shown below, but the present invention is not limited thereto. All "parts" in the examples indicate parts by weight.

(Examples 1 to 8 and Comparative Examples 1 to 4) Example 1 (1) Preparation of Coating Solution (KB-1) for Thermosensitive Recording Layer [Preparation of Capsule Solution (CB-1) of Diazo Compound] After adding 6 parts of the following (C-1) and 0.18 part of n-butanol as a wall agent to 19 parts of ethyl acetate and reacting at room temperature for 1 hour, 4.2 parts of the following (C-2) were dissolved, Below (C-3)
9.9 parts were added and mixed uniformly to obtain a liquid I.

Next, Kao Corporation's Demol MS 0.11
Parts were dissolved in 11.6 parts of water, and then 2% of the following (C-4)
5.5 parts of an aqueous solution and an 8 wt% aqueous solution of phthalated gelatin 3
Solution I was added while 8.5 parts were added and uniformly mixed at 40 ° C, and the mixture was homogenized at 40 ° C, 10000 r.p.
The emulsion was dispersed for 10 minutes at m. 20 parts of water was added to the obtained emulsion to homogenize it, and the mixture was allowed to undergo an encapsulation reaction at 40 ° C. for 3 hours with stirring to obtain a capsule liquid (CB-1). The capsule particle size was about 0.5 μm.

[0077]

[Chemical 18]

[Preparation of coupler emulsion (CN-1)] 4 parts of the following coupler (D-1) in 2 parts of ethyl acetate, 2 parts of the above-mentioned hydrophobic guanidine derivative (I-5) of the present invention, and (D)
-2) 2 parts, (D-3) 3 parts below, (D-4) 3 below
Part, the piperazine derivative (II-3) 3.1 of the present invention
Part, the following (D-5) 2 parts, tricresyl phosphate 0.64 parts, diethyl maleate 0.32 parts, and 70% methanol solution of calcium dodecylbenzenesulfonate 0.75 parts were dissolved to obtain solution II. It was

Next, 50 parts of a 15 wt% aqueous solution of lime-processed gelatin and 24.5 parts of water were uniformly mixed at 40 ° C., and then the solution II was added, and the mixture was mixed with a homogenizer at 40 ° C. for 10 minutes.
The emulsion was dispersed at 000 rpm for 10 minutes. The obtained emulsion was stirred at 40 ° C. for 2 hours to remove ethyl acetate, and then the weight of volatilized ethyl acetate and water was supplemented with water to obtain a coupler emulsion (CN-1).

[0080]

[Chemical 19]

[Preparation of coating liquid] 4 parts of (CB-1), 1.6 parts of water, 2.7 parts of a 4% aqueous solution of boric acid, and 2.5 parts of a 48% aqueous solution of styrene-butadiene latex at 40 ° C. After uniformly mixing, 14.7 parts of (CN-1) was added and uniformly mixed to obtain a heat-sensitive recording layer coating solution (KB-1).

(2) Preparation of coating solution for protective layer (PB-1) Polyvinyl alcohol (degree of polymerization 1700, degree of saponification 88)
%) 10% aqueous solution 32 parts, water 36 parts, the following (W-1) 2
% Aqueous solution 8.4 parts uniformly mixed to form a protective layer coating solution (PB
-1) was obtained.

[0083]

[Chemical 20]

(3) Application On a printing paper support prepared by laminating polyethylene on high-quality paper, coating (KB-1) and (PB-1) were carried out in this order with a wire bar and drying at 50 ° C. was carried out. A desired thermosensitive recording material was obtained. The coating amount as solid content is 7.9 g / each
It was m ² and 1.05 g / m ² .

(4) Thermal recording Using a thermal head (KST type) manufactured by Kyocera Corporation,
Recording energy per unit area is 0 to 25 mJ / mm
^The power applied to the thermal head and the pulse width are determined so as to be ² and thermal printing is performed on the thermosensitive recording layer to obtain a yellow image, and then a full-scale light is irradiated for 10 seconds using an ultraviolet lamp with a central emission wavelength of 420 nm and an output of 40 W. Irradiated.

(5) Fading test The above sample was subjected to 12,000 Lux fluorescent lamp fading tester.
Light irradiation was continuously performed for a week, and an image discoloration test was performed. For the density measurement, an X-Rite 310TR was used to examine the density change in which the initial reflection density was about 1.1.

Example 2 Instead of 3.1 parts of (II-3) used in Example 1,
A thermosensitive recording material was obtained in the same manner as in Example 1 except that 4 parts of (II-14) was used, and a fading test was conducted in the same manner as in Example 1.

Example 3 Instead of 3.1 parts of (II-3) used in Example 1,
A thermosensitive recording material was obtained in the same manner as in Example 1 except that 3.7 parts of (II-9) was used, and a fading test was conducted in the same manner as in Example 1.

Example 4 Instead of 3.1 parts of (II-3) used in Example 1,
A thermosensitive recording material was obtained in the same manner as in Example 1 except that 5.5 parts of (II-18) was used, and a fading test was conducted in the same manner as in Example 1.

Example 5 Instead of 3.1 parts of (II-3) used in Example 1,
A thermosensitive recording material was obtained in the same manner as in Example 1 except that 4.4 parts of (II-38) was used, and a fading test was conducted in the same manner as in Example 1.

Example 6 Instead of 3.1 parts of (II-3) used in Example 1,
A thermosensitive recording material was obtained in the same manner as in Example 1 except that 7.7 parts of (II-20) was used, and a fading test was conducted in the same manner as in Example 1.

Example 7 Instead of 2 parts of (I-5) used in Example 2, (I-
1) A thermosensitive recording material was obtained in exactly the same manner as in Example 2 except that 1.6 parts were used, and a fading test was conducted in the same manner as in Example 2.

Example 8 Instead of 2 parts of (I-5) used in Example 2, (I-3
7) A thermosensitive recording material was obtained in exactly the same manner as in Example 2 except that 3 parts were used, and a fading test was conducted in the same manner as in Example 2.

Comparative Example 1 A thermosensitive recording material was obtained in the same manner as in Example 1 except that (I-5) and (II-3) used in Example 1 were excluded, and a fading test was conducted in the same manner as in Example 1. I went.

Comparative Example 2 A thermosensitive recording material was obtained in the same manner as in Example 1 except that (II-3) used in Example 1 was excluded, and a fading test was conducted in the same manner as in Example 1.

Comparative Example 3 A thermosensitive recording material was obtained in the same manner as in Example 1 except that (I-5) used in Example 1 was excluded, and a fading test was conducted in the same manner as in Example 1.

Comparative Example 4 A thermosensitive recording material was obtained in the same manner as in Example 3 except that (I-5) used in Example 3 was excluded, and a fading test was conducted in the same manner as in Example 3. Table 1 shows the density ratios before and after the yellow fading test in Examples 1 to 8 and Comparative Examples 1 to 4.

As a result, by incorporating the hydrophobic guanidine derivative and the piperazine derivative into the heat-sensitive recording layer, fading was less likely to occur and the light fastness was improved.

[0099]

[Table 1]

(Examples 9 to 11 and Comparative Example 5) Example 9 (1) Preparation of coating liquid (KB-2) for heat-sensitive recording layer [Preparation of capsule liquid (CB-2) of diazo compound] Ethyl acetate 19 parts below (E-1) 2.8 parts, below (E-
2) After dissolving 0.56 part, 5.9 parts of tricresyl phosphate and 2.5 parts of (C-3) below were added and mixed uniformly. Next, the following (C-
1) 7.6 parts was added and mixed uniformly to obtain a solution I.

Next, solution I was added while uniformly mixing 46.1 parts of an 8 wt% aqueous solution of phthalated gelatin, 17.5 parts of water, and 2 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate at 40 ° C. Then, using a homogenizer, 40 ℃, 1
The emulsion was dispersed at 0000 rpm for 10 minutes. 20 parts of water was added to the obtained emulsion to homogenize it, and then 40 while stirring.
Capsule liquid (CB
-2) was obtained. The particle size of the capsule was 0.35 μm.

[0102]

[Chemical 21]

[Preparation of Coupler Emulsion (CN-2)] 10.6 parts of ethyl acetate, 3 parts of the following coupler (F-1), 3 parts of the above-mentioned hydrophobic guanidine derivative (I-5) of the present invention, and the following: (D-2) 3 parts, below (D-4) 6 parts, below (D-
5) 6 parts, the following (F-2) 3 parts, the above-mentioned piperazine derivative (II-3) 1.7 parts of the present invention, tricresyl phosphate 0.48 parts, diethyl maleate 0.24 parts, dodecylbenzene. 0.53 parts of a 70% methanol solution of calcium sulfonate was dissolved to obtain a liquid II.

Next, 41.7 parts of a 15% by weight aqueous solution of lime-processed gelatin and 33.9 parts of water were uniformly mixed at 40 ° C., and then the solution II was added, and a homogenizer was used at 40 ° C. at 10,000 rpm. And emulsified and dispersed for 10 minutes. After stirring the obtained emulsion at 40 ° C. for 2 hours to remove ethyl acetate,
The volatilized ethyl acetate and the weight of water were supplemented with water to obtain a coupler emulsion (CN-2).

[0105]

[Chemical formula 22]

[Preparation of coating solution] (CB-2) 3.6 parts,
2.8 parts of water, 15% by weight aqueous solution of lime-processed gelatin.
After uniformly mixing 5 parts and 1.4 parts of a 48% aqueous solution of styrene-butadiene latex at 40 ° C., (CN-2)
7.9 parts was added and uniformly mixed to obtain a heat-sensitive recording layer coating solution (KB-2).

(3) Application On a printing paper support prepared by laminating polyethylene on high-quality paper, coating (KB-2) and (PB-1) were carried out in this order with a wire bar, and drying was carried out at 50 ° C. A desired thermosensitive recording material was obtained. The coating amount as solid content is 6.1 g /
It was m ² and 1.05 g / m ² .

(4) Thermal recording Using a thermal head (KST type) manufactured by Kyocera Corporation,
Recording energy per unit area is 0-40 mJ / mm
^After setting the applied power and pulse width to the thermal head so that it becomes ² , thermal printing is performed on the thermosensitive recording layer to obtain a magenta image, and then the entire surface is illuminated for 15 seconds using an ultraviolet lamp with an emission center wavelength of 365 nm and an output of 40 W. Irradiated.

(5) Fading test The above sample was subjected to 3 times with a 12000 Lux fluorescent lamp fading tester.
Light irradiation was continuously performed for a day, and an image discoloration test was performed. For the density measurement, an X-Rite 310TR was used to examine the density change in the portion where the initial reflection density of magenta was about 1.1.

Example 10 Instead of 1.7 parts of (II-3) used in Example 9,
A thermosensitive recording material was obtained in the same manner as in Example 9 except that 2.2 parts of (II-14) was used, and a fading test was conducted in the same manner as in Example 1.

Example 11 Instead of 1.7 parts of (II-3) used in Example 9,
A thermosensitive recording material was obtained in the same manner as in Example 9 except that 2.5 parts of (II-38) was used, and a fading test was conducted in the same manner as in Example 1.

Comparative Example 5 A thermosensitive recording material was obtained in the same manner as in Example 1 except that 1.7 parts of (II-3) used in Example 9 was not used, and a fading test was conducted in the same manner as in Example 9. went. The density ratios before and after the fading test of magenta in Examples 9 to 11 and Comparative Example 5 are shown in Table 2.
Shown in.

As a result, the light fastness was improved by incorporating the hydrophobic guanidine derivative and the piperazine derivative into the heat-sensitive recording layer.

[0114]

[Table 2]

Examples 12 to 14 and Comparative Example 6 Example 12 In addition to the heat-sensitive recording layer coating solution of Example 1, the heat-sensitive recording layer coating solution and protective layer solution of Example 9, one type of heat-sensitive recording layer A coating liquid and one type of intermediate layer coating liquid were newly prepared.

(1) Preparation of third thermosensitive recording layer liquid [Preparation of capsule liquid of electron-donating dye precursor] Crystal violet lactone which is an electron-donating dye precursor
After dissolving 3.0 parts in 20 parts of ethyl acetate, 20 parts of alkylnaphthalene, which is a high boiling point solvent, was added and heated to uniformly mix. Then, as a capsule wall agent in this mixed solution,
20 parts of xylylene diisocyanate / trimethylolpropane adduct was added and stirred uniformly.

Next, a 6% by weight aqueous solution of separately prepared polyvinyl alcohol (polymerization degree 1700, saponification degree 88%) 5
The above electron-donating dye precursor solution was added to 4 parts, and the mixture was emulsified and dispersed using a homogenizer. 68 parts of water was added to the obtained emulsion for homogenization, the temperature was raised to 50 ° C. with stirring, and the encapsulation reaction was carried out for 3 hours to obtain a target capsule solution. The average particle size of the capsule was 1.6 μm.

[Preparation of Dispersion Liquid of Electron-Accepting Compound] 30 parts of bisphenol A, which is an electron-accepting compound, was added to 150 parts of a 4% by weight aqueous solution of polyvinyl alcohol, and dispersed for 24 hours using a ball mill to prepare a dispersion liquid. . The average particle size of the electron-accepting compound in the dispersion was 1.2 μm.

[Preparation of Coating Liquid] The above electron-donating dye precursor capsule liquid and the electron-accepting compound dispersion liquid were mixed so that the ratio of the electron-donating dye precursor / electron-accepting compound was 1/2. To prepare a coating solution.

(2) Preparation of intermediate layer liquid (MC-1) 50 parts by weight aqueous solution of 15% by weight lime-processed gelatin, water 11
Parts, 2 parts of a 2% aqueous solution of (C-4) were uniformly mixed at 42 ° C. to obtain an intermediate layer liquid (MC-1).

[0121]

[Chemical formula 23]

(3) Coating On a photographic paper support prepared by laminating polyethylene on high-quality paper, use a wire bar to apply a third heat-sensitive layer coating solution (MC-
1), the heat-sensitive layer (second heat-sensitive layer) coating liquid of Example 9, (MC
-1), the heat-sensitive layer (first heat-sensitive layer) coating solution of Example 1 and the protective layer solution were sequentially applied and dried at 50 ° C. to obtain the intended multicolor heat-sensitive recording material. The coating amount as a solid content is 5.2 g / m ² , 3.0 g / m ² , 6.4 g / m ² ,
The values were 3.0 g / m ² , 7.9 g / m ² and 1.05 g / m ² . (4) Thermal recording Using a Kyocera thermal head (KST type),
Recording energy per unit area is 0 to 25 mJ / mm
Determine the power applied to the thermal head and the pulse width so that it becomes ^2, and after thermally printing on the first thermosensitive recording layer to obtain a yellow image, the emission center wavelength is 420 nm and the output is 40 W.
The entire surface was irradiated with light using the ultraviolet lamp for 10 seconds.

Then, the power applied to the thermal head and the pulse width were determined so that the recording energy per unit area was 0 to 40 mJ / mm ^2, and the second heat sensitive recording layer was formed.
After thermal printing and obtaining a magenta image, the emission center wavelength was 3
The entire surface was irradiated with light for 15 seconds using an ultraviolet lamp of 65 nm and an output of 40 W.

Finally, the applied power to the thermal head and the pulse width were determined so that the recording energy per unit area was 0 to 60 mJ / mm ^2, and thermal printing was performed on the third thermosensitive recording layer to obtain a cyan image. . By this, magenta, yellow, cyan, cyan + magenta (blue),
Magenta + yellow (red), cyan + yellow (green) and cyan + magenta + yellow (black)
An image record of was obtained.

(5) Fading test The above sample was subjected to 12000 Lux with a fluorescent lamp fading tester.
Light irradiation was continuously performed for a week, and an image discoloration test was performed. For the density measurement, X-Rite 310TR was used to examine the density change in the portions where the initial reflection densities of magenta and yellow were about 1.1, respectively.

Example 13 Instead of the thermosensitive recording layer coating liquid of Example 1 and the thermosensitive recording layer coating liquid of Example 9 used in Example 12, the thermosensitive recording layer coating liquid of Example 2 and the thermosensitive recording layer of Example 10 were used. A thermosensitive recording material was obtained in exactly the same manner as in Example 12 except that the recording layer coating liquid was used, and a fading test was conducted in the same manner as in Example 12.

Example 14 Instead of the thermosensitive recording layer coating liquid of Example 1 and the thermosensitive recording layer coating liquid of Example 9 used in Example 12, the thermosensitive recording layer coating liquid of Example 5 and the thermosensitive recording layer of Example 11 were used. A thermosensitive recording material was obtained in exactly the same manner as in Example 12 except that the recording layer coating liquid was used, and a fading test was conducted in the same manner as in Example 12.

Comparative Example 6 Instead of the thermosensitive recording layer coating solution of Example 1 and the thermosensitive recording layer coating solution of Example 9 used in Example 12, the thermosensitive recording layer coating solution of Comparative Example 2 and the thermosensitive recording layer of Comparative Example 5 were used. A thermosensitive recording material was obtained in exactly the same manner as in Example 12 except that the recording layer coating liquid was used, and a fading test was conducted in the same manner as in Example 12.

Table 3 shows the density ratios before and after the fading test for yellow and the density ratios before and after the fading test for magenta in Examples 12 to 14 and Comparative Example 6, respectively. As a result, by incorporating the hydrophobic guanidine derivative and the piperazine derivative into the heat-sensitive recording layer, yellow and magenta were less likely to fade and the light fastness was improved.

[0130]

[Table 3]

[0131]

The heat-sensitive recording material of the present invention contains at least one hydrophobic guanidine derivative and at least one piperazine derivative in the heat-sensitive recording layer containing a diazo compound and a coupler which reacts with the diazo compound to develop a color. Excellent light fastness.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location 6956-2H B41M 5/18 112

Claims (3)

[Claims] 1. A thermosensitive recording material comprising at least one thermosensitive recording layer containing, as a main component, a diazo compound and a coupler which reacts with the diazo compound to form a color on a support, wherein the thermosensitive recording layer has a hydrophobic guanidine. A heat-sensitive recording material comprising at least one derivative and at least one piperazine derivative. 2. The heat-sensitive recording material according to claim 1, wherein at least one color-forming component of the diazo compound and the coupler which is a color-forming component is encapsulated in microcapsules. 3. The heat-sensitive recording material according to claim 1, wherein among the color-forming components, the coupler is in the same emulsion as the hydrophobic guanidine derivative and the piperazine derivative.