JPS6255191A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance a titled material in shelf stability in a raw state, i.e. before being printed, and in thermal color developing properties, by a method wherein a micro-capsule contains a diazo compound along with a polymerizable compound having ethylene unsaturated bonds. CONSTITUTION:On a substrate, a recording layer containing a diazo compound and a coupling ingredient is formed. A micro-capsule contains the diazo compound along with a polymerizable compound having ethylene unsaturated bonds. The diazo compound can create a coupling reaction with the coupling ingredient to develop color and can be dissolved by light irradiation. the aforesaid polymerizable compound included in the micro-capsule has ethylene unsaturated bonds in its chemical structure and exists in the chemical form of monomer, prepolymer, mixture or copolymer of the monomer and prepolymer. The diazo compound used as a coupler can be fixed by fully exposing the thermal recorded material. In this case, the polymerizable compound having ethylene unsaturated bonds prevents scummings.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat-sensitive recording material, and particularly to a fixable diazo compound-based heat-sensitive recording material.

(Prior Art) As a recording material used in a heat-sensitive recording method, a leuco color-forming heat-sensitive recording material is usually used. However, this heat-sensitive recording material has the disadvantage that color develops in unexpected places due to harsh handling, heating, or adhesion of solvents after recording, which stains the recorded image. In recent years, research has been actively conducted on diazo color-forming heat-sensitive recording materials as heat-sensitive recording materials that do not have these drawbacks. For example, Japanese Patent Application Laid-open No. 57-123086, Journal of the Institute of Image Electronics Engineers, 11°290
(1982), etc., thermal recording is performed on a recording material using a diazo compound, a coupling component, and a basic component (including substances that become basic when heated), and then light irradiation is performed to record the raw material. It decomposes the diazo compound in the reaction and stops color development.

It is true that this method can stop color development in areas that do not require recording (hereinafter referred to as fixation), but this recording material also undergoes pre-coupling gradually during storage, resulting in undesirable coloring (fogging). may occur. To this end, it has been attempted to prevent contact between the components and prevent pre-coupling by making one of the coloring components exist in the form of discontinuous particles (solid dispersion). However, the storage stability (hereinafter referred to as "raw storage stability") is still insufficient, and the thermochromic color development property is also deteriorated. On the other hand, in order to minimize contact between the components, it is known to separate the diazo compound and the camping component as separate layers (for example, as described in the above-mentioned Japanese Patent Application Laid-Open No. 123086/1986).
Although this method improves raw storage stability, the thermochromic property is greatly reduced, and it cannot respond to short high-speed recording during pulses, making it impractical. Furthermore, as a method to satisfy both raw storage stability and thermochromic properties, either the power/knobling component or the basic substance is replaced with a non-polar waxy substance (Japanese Patent Application Laid-open No. 57-4
It is known to isolate it from other components by encapsulating it with a hydrophobic polymer substance (Japanese Patent Application Laid-open No. 57-192944). However, these encapsulation methods involve dissolving wax or polymeric substances in their solvents, and dissolving or dispersing coloring components in these solutions to form capsules. This differs from the concept of a normal capsule that is surrounded by a shell, so when a capsule is formed by dissolving a coloring component, the coloring component does not become the core material of the capsule and mixes uniformly with the encapsulating material. . For this reason, pre-coupling gradually progresses at the wall interface of the capsule during storage, and the raw storage stability is not fully satisfied. In addition, when a color-forming component is dispersed and formed, the color-forming reaction does not occur unless the walls of the capsule are thermally melted, resulting in a decrease in thermal color-forming properties. Furthermore, there was a manufacturing problem in that the wax or the solvent used to dissolve the polymer substance had to be removed after the capsules were formed, and the material was not fully satisfactory as a heat-sensitive recording material.

In order to solve these problems, at least one of the components involved in the color reaction is contained in a core material, and a wall is formed around this core material by polymerization to form a microcapsule (Japanese Patent Application Laid-Open No. 59-1999-1). 190886) was disclosed.

(The problem that the invention is trying to solve) However,
Even in the heat-sensitive recording material using the above-mentioned microencapsulation, it was not possible to avoid the drawback that the background portion (portion other than the recorded image) becomes slightly yellowish when thermally recorded and then photofixed.

Therefore, the first object of the present invention is to provide a heat-sensitive recording material which has a white background tone, has excellent shelf life, and has high thermochromic properties.

A second object of the present invention is to provide a heat-sensitive recording material that can be fixed by photodecomposing unreacted diazo compounds after heat recording.

A third object of the present invention is to provide a heat-sensitive recording material with excellent manufacturing suitability.

(Means for Solving the Problems) The above aspects of the present invention are such that in a heat-sensitive recording material provided with a recording layer containing at least a diazo compound and a coupling component on a support, the diazo compound is This was achieved by a heat-sensitive recording material characterized in that it is contained in microcapsules together with a polymerizable compound having an unsaturated bond.

After the heat-sensitive recording material of the present invention is thermally colored, it can be uniformly irradiated with light to stop the thermal coloring property of the uncolored diazo compound. Further, after imagewise exposure, the diazo compound in the unexposed area can be thermally colored by uniformly heating.

The diazo compound used in the heat-sensitive recording material of the present invention is a diazonium salt represented by the general formula ArN2+X-,
It is a compound that can develop color by causing a cambling reaction with a coupling component, and can be decomposed by light irradiation.

(In the formula, Ar represents a substituted or unsubstituted aromatic moiety, and N
2+ represents a diazonium group, and X- represents an acid anion. ) The aromatic moiety is represented by the following general formula.

In the formula, Y represents a substituted amino group, an alkoxy group, an arylthio group, an alkylthio group, or an acylamino group, and R represents an alkyl group, an alkoxy group, an arylamino group, or a halogen (H, Br, CI, F).

Preferred examples of the substituted amino group for Y include a monoalkylamino group, dialkylamino group, arylamino group, morpholino group, piperidino group, and pyrrolidino group.

Specific examples of diazonium that forms salts include 4-diazo-1-dimethylaminobenzene, 4-diazo-1-diethylaminobenzene, 4-diazo-1-dipropylaminobenzene, and 4-diazo-1-methylbenzylamino. Benzene, 4-diazo-1-dibenzylaminobenzene, 4-diazo-1-ethylhydroxyethylaminobenzene, 4-diazo-1-diethylamino-3-methoxybenzene, 4-diazo-1-dimethylamino-2-methyl Benzene, 4-diazo-1-benzoylamino-2,
5-jethoxybenzene, 4-diazo-1-morpholinobenzene, 4-diazo-1-morpholino-2,5-jethoxybenzene, 4-diazo-1-morpholino-2,5
-dibutoxybenzene, 4-diazo-1-anilinobenzene, 4-diazo-1-tolylmercapto-2,5-
Examples include jetoxybenzene, 4-diazo-1,4-methoxybenzoylamino-2,5-jethoxybenzene, and the like.

Specific examples of acid anions include CnF2n+1coo-
<n is an integer from 3 to 9), CmF2m+ISO, -(m
is an integer from 2 to 8), (CIIF2J!+1302)2'
c) (-(ffi is an integer from 1 to 18), and 151 (3t
, 1798C11H23CO * /Amount φ = - (n is an integer of 3 to 3) (n is an integer of 3 to 3) BF4, PF6-, etc. are mentioned.

In particular, acid anions include those containing a perfluoroalkyl group or a fluoroalganyl group, and PF.
6- shows less increase in fog during raw storage (preferable).

Specific examples of the diazo compound (diazonium salt) include the following examples.

0C4H9 C4H9 C4H9 C4H9 C2H5 C2H5 0C2H5C(CH3)3 C4H9 0C4H0 OC4H3 C4H9 The coupling component used in the present invention has a component that promotes the formation of a dye by coupling with a diazo compound (diazonium salt) in a basic atmosphere. In some cases, camplination occurs even in the absence of a basic substance as a coloring aid.

Specific examples of camping components in which a basic substance is preferably present include resorcinol, phloroglucin, 2.3-
Sodium dihydroxynaphthalene-6-sulfonate,
1.5-dihydroxynaphthalene, 2.3-dihydroxynaphthalene, 2゜3-dihydroxy-6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid anilide, 2-hydroxy-3-naphthoic acid-2''-methylanilide , 2-hydroxy-3-naphthoic acid ethanolamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid-N-dodecyl-oxy-propylamide, 2-hydroxy-3-naphthoic acid tetra Examples include decylamide.

Examples of coupling components that do not require the presence of a basic substance include compounds having active methylene in the molecule, aromatic amine compounds, aromatic hydroxy compounds having a basic group in the molecule, and the like.

Examples of active methylene compounds include β-ketocarboxylic acid amides (e.g., benzoylacetanilide, pivaloylacetanilide, L,3-bis(benzoylacetamino)toluene, 1,3-bis(pivaloylacetaminomethyl)benzene , etc.], pyrazolones [e.g. 3
-methyl-1-phenylpyrazolone, 3-hexylcarbamoyl-1-phenylpyrazolone, 3-myristoylamino-1-(2,4,6-)lichlorophenyl)pyrazolone, etc.], barbylic acids [e.g. 3-didodecylbarbylic acid, 1,3-dicyclohexylbarbylic acid, ■-octyl-3-stearylbarbylic acid, etc.), 1,3-cyclohexanediones [e.g.
．． 5-dimethyl-1゜3-cyclohexanedione, 5,
5-dimethyl-4-phenyl-1,3-cyclohexanedione, etc.).

As aromatic amine compounds, α-naphthylamine,
β-naphthylamine, l-anilino-naphthalene, 2-
Anilino-naphthalene, 3-amino-diphenylamine, 4,4'-diaminodiphenylmethane, N,N-dicyclohexylaniline, 2-aminocarbazole, 2
- Organic and inorganic acid salts of aromatic amines such as phenylindole, 1-phenyl-2-methylindole and P-)luenesulfonate of N,N-dimethylaniline, α-naphthylamine hydrochloride, etc. be.

Examples of aromatic hydroxy compounds having a basic group in the molecule include 2-hydroxy-3-naphthoic acid-3'-morpholinopropylamide, 2-hydroxy-3-naphthoic acid-2'-diethylaminoethylamide, and 2-hydroxy-3-naphthoic acid-2'-diethylaminoethylamide. -3-naphthoic acid-3-piperidinopropylamide,
2-Hydroxy-3-naphthoic acid-3°-piperidinopropylamide, 2-hydroxy-3-naphthoic acid-P
-(3''-N'-cyanoguanidinopropyl)oxyanilide, salicylic acid-P-(3'-morpholinopropyl)oxyanilide, l-naphthol-4-sulfonic acid-3''-diethylaminopropylamide, 8-
Aromatic hydroxy compounds having residues such as hydroxyquinoline-4-sulfonic acid-2''-diethylaminoethylamide and organic carboxylic acid salts of amines that generate basicity upon heating (e.g. 2-hydroxy-3-naphthoate@ -3゛-Trichloroacetate of morpholinopropylamide, 1-naphthol-4-sulfone!l-3''-
phenylthioacetate ring of diethylaminopropylamide], etc.

In the present invention, an image of any color tone can be obtained by using two or more of the above-mentioned coupling components in combination.

In the present invention, water-releasable or water-insoluble basic substances, substances that generate alkali upon heating (hereinafter referred to as basic substances), and the like can be used as color development aids. The basic substances used as such coloring aids are:
inorganic and organic ammonium salts, organic amines and amides,
Urea and thiourea and their derivatives, thiazoles, viroles, torimishins, piperazines, guanidines, indoles, imidazoles, imidacillins, triazoles, morpholines, piperidines, amidines,
Nitrogen-containing compounds such as formazines and pyridines, and specific examples thereof include ammonium acetate, tricyclohexylamine, tribenzylamine, octadecylbenzylamine, stearylamine, allyl urea, thiourea, methylthiourea, Allylthiourea, ethylenethiourea, 2-benzylimidazole, 4-phenylimidazole, 2-phenyl-4-methyl-imidazole, 2-undecyl-imidacillin, 2.4.5-
) Lift-true 2-imidacillin, 1゜2-diphenyl-
4,4-dimethyl-2-imidacyline, 2-phenyl-
2-Imidacillin, 1゜2.3-)riphenylguanidine, 1,2-ditolylguanidine, 1,2-dicyclohexylguanidine, 1,2.3-1lycyclohexylguanidine, guanidine trichloroacetate, N , N”
-dibenzylpiperazine, 4.4°-dithiomorpholine, morpholinium trichloroacetate, 2-amino-benzothiazole, 2-benzoylhydrazino-benzothiazole, and the like. Two or more of these basic substances can also be used in combination.

The coupling agent and/or the basic substance can be contained in a separate microcapsule from the diazo compound or simply added to the layer of the microcapsule containing the diazo compound. When not included in microcapsules,
It is preferable to finely disperse it in the form of particles. In addition, in the case of a coupling agent that can couple with a diazo compound only in a basic atmosphere, it is natural that the diazo compound and the coupling agent can be contained in the same microcapsule.

In the present invention, the coating amount of the diazo compound is 0°05~
It is preferable that the amount is 5.0 g/rrl, and it is preferable to use the camping agent in a proportion of 0.01 to 10 parts by weight and the basic substance in a proportion of 0 to 20 parts by weight per 1 part by weight of the diazo compound.

In the present invention, a polymerizable compound having an ethylenically unsaturated bond (referred to as a lower vinyl hexamer) to be encapsulated in a microcapsule together with a diazo compound is a compound having at least one ethylenically unsaturated bond in its chemical structure. Saturated bond (
A compound having a vinyl group, vinylidene group, etc.),
It has chemical forms such as monomers, prepolymers, dimers, trimers and other oligomers, mixtures thereof and copolymers thereof. Examples thereof include unsaturated carboxylic acids and their salts, esters with aliphatic polyhydric alcohol compounds, amides with aliphatic polyhydric amine compounds, and the like.

Specific examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid,
Maleic acid, etc.

Examples of the salts of unsaturated carboxylic acids include sodium salts and potassium salts of the aforementioned acids.

Specific examples of esters of aliphatic polyhydric alcohol compounds and unsaturated carboxylic acids include acrylic esters such as ethylene glycol diacrylate, triethylene glycol triacrylate, 1°3-butanediol diacrylate, tetramethylene glycol diacrylate,
Propylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, 1,4-cyclohexanediol diacrylate, tetraethylene glycol diacrylate,
Pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol diacrylate, dipentaerythritol triacrylate,
Examples include dipentaerythritol tetraacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, and polyester acrylate oligomers. Examples of methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol triacrylate, trimethylolpropane trimethacrylate, trimethylolethane triacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, pentaerythritol dimethacrylate, and pentaerythritol dimethacrylate. Erythritol trimethacrylate, dipentaerythritol dimethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis-[p-(3-methacryloxy-
Examples include 2-hydroxypropoxy)phenyl]dimethylmethane, bis-[p-acryloxyethoxy)phenyl]dimethylmethane, and the like. As itaconic acid, ethylene glycol shiitaconate, propylene glycol shiitaconate, 1,4-butanediol shiitaconate,
Examples include tetramethylene glycol shiitaconate, pentaerythritol shiitaconate, sorbitol tetrataconate, and the like. Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaeryloritol dicrotonate, and sorbitol tetracrotonate. Isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, sorbitol tetraisocrotonate, and the like. Examples of maleic esters include ethylene glycol malate, triethylene glycol simarate, pentaerythritol simarate, and sorbitol tetramaleate. Furthermore, mixtures of the aforementioned esters may also be mentioned.

Specific examples of amides of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylenebis-acrylamide, methylenebis-methacrylamide, 1゜6-hexamethylenebis-acrylamide, 1゜6-hexamethylenebis-
Examples include methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide, and the like.

Another example is 211! Examples include vinyl urethane compounds containing two or more polymerizable vinyl groups in one molecule, which are obtained by adding a vinyl monomer containing a hydroxyl group represented by the following general formula to a polyisocyanate compound having the above isocyanate groups. .

CH2=C(R)COOCH2CH(R')OH (However, R and R'' represent H or CH3.) Preferred vinyl monomers used in the present invention are monofunctional or polyfunctional methacrylates and polyvalent acrylates. .

(Function) When a diazo compound is used as a color former as in the present invention, fixation can be achieved by exposing the entire surface of the recording material after thermal recording to light. In this case, the skin becomes stained brown due to decomposition of the diazo compound, but the polymerizable compound having an ethylenically unsaturated bond used in the present invention prevents the above-mentioned skin stain, although the details of its action are not clear. I can do it.

The amount of vinyl monomer used in the present invention is 0.2 to 20 parts by weight, preferably 1 to 10 parts by weight, per 1 part by weight of the diazo compound.

The above-mentioned vinyl monomer not only prevents background staining during photofixing, but also maintains good thermochromic properties by incorporating it into the core of microcapsules together with a diazo compound, while also allowing the coloring reaction to occur at room temperature. It also contributes to preventing contact between the substances involved and improving shelf life. In this case, by substituting a part of the vinyl monomer with a water-insoluble organic solvent, the reactivity during heating recording can be increased and the color density of the recording material can be improved. As the organic solvent that can be used for this purpose, it is preferable to use one with a boiling point of 180° C. or higher, since the loss of fujigas during raw storage is small. Organic solvents that can be preferably used in the present invention are:
These include phosphoric acid esters, phthalic acid esters, other carboxylic acid esters, fatty acid amides, alkylated biphenyls, alkylated terphenyls, chlorinated paraffins, alkylated naphthalenes, diarylethanes, etc. Specific examples include tricresyl phosphate, phosphorus, etc. trioctyl phosphate, octyldiphenyl phosphate, tricyclohexyl phosphate, dibutyl phthalate, dioctyl phthalate, dilaurate phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol dibenzoate, dioctyl sebacate, dibutyl sebacate, dioctyl adipate, Trioctyl mellitate, acetyltriethyl citrate, octyl maleate, dibutyl maleate, isopropylbiphenyl, isoamyl biphenyl, chlorinated paraffin, diisopropylnaphthalene, 1.1゛-ditolylethane, 2.4-di-tert-aminophenol, N,N -dibutyl-2-butoxy-5-tert-
Examples include octylaniline. Among these, diethyl phthalate, dibutyl phthalate, tricresyl phosphate,
Ester solvents such as dibutyl maleate are particularly preferred. The organic solvent is used as a core material in the emulsified droplets (consisting of a diazo compound, a vinyl monomer, an organic solvent, a capsule wall forming substance, etc.) in an amount of 10 to 70% by weight, especially 20 to 55% by weight.
Preferably, the content is % by weight.

Next, the microcapsules used in the present invention will be explained in detail.

Microcapsules that can be used in the present invention can be appropriately selected from known microcapsules, but
In particular, it is preferable to select a material that is difficult to be destroyed by heat or pressure, from the viewpoint of the storage stability of the recording material and its ease of handling.

Such preferable microcapsules are those in which reactive substances present in the core and outside of the microcapsules are heated so that they permeate through the microcapsule walls and react.

Therefore, the capsule walls of the microcapsules used in the present invention do not necessarily need to be melted by heat, and it is preferable that the walls have a higher melting point because they have better shelf life.

Furthermore, as the size of the microcapsules increases, the thermal contact between the core substance of the microcapsules and other substances decreases with short heating, resulting in a decrease in color density.
The average particle size is preferably 20μ or less, particularly preferably 8μ or less.

Next, a method for manufacturing the microcapsules used in the present invention will be described in detail.

The microcapsules used in the present invention are preferably made by emulsifying a core material containing a diazo compound and then forming a wall of a polymer material around the oil droplets. In this case, the reactant forming the polymeric substance is added to the interior of the oil droplet and/or to the exterior of the oil droplet. Specific examples of such polymeric substances include polyurethane, polyurea, polyamide, polyester, polycarbonate urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl Examples include alcohol.

Two or more of these polymeric substances can also be used in combination.

Among the above-mentioned polymeric substances, polyurethane, polyurea, polyamide, polyester, and polycarbonate are preferred in the present invention, and polyurethane and polyurea are particularly preferred.

The microcapsule wall using the above-mentioned polymeric substance is particularly effective when using a microencapsulation method by polymerizing a reactant from inside the oil droplet. However, by using this method, capsules having a uniform particle size and excellent storage stability can be obtained in a short period of time and are suitable as recording materials.

Such techniques and specific examples of compounds are described in U.S. Pat. Nos. 3,726,804 and 3,796.669.

For example, when polyurethane is used as the capsule wall material, a polyvalent isocyanate and a second substance (e.g. polyol, polyamine) that reacts with it to form the capsule wall are used.
is mixed into an oily liquid to be encapsulated, emulsified and dispersed in water, and then the temperature is raised to cause a polymer formation reaction at the oil droplet interface to form microcapsule walls.

At this time, an auxiliary solvent with a low boiling point and strong dissolving power can be used in the oily liquid.

In this case, regarding the polyisocyanate used and the polyol and polyamine that react with it, US Pat. No. 3,
No. 793.268, Special Publication No. 48-40347, No. 49
-24159, JP-A-48-80191, JP-A-48-
No. 84086, and they can also be used.

Furthermore, a tin salt or the like can also be used in combination to promote the urethanization reaction. Note that polyvalent isocyanate can react with water to form a polymer film.

Furthermore, by combining polyvalent isocyanate, which is the first wall-forming substance, and polyol, which is the second wall-forming substance, the thermal permeability of the reactive substance can be changed arbitrarily.

In the present invention, examples of the polyvalent isocyanate as the first wall film-forming substance include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1 , 4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3°
-dimethoxy to 4.4'-biphenyl diisocyanate, 3,3'-dimethyldiphenylmethane-4'4'-diisocyanate, xylylene-1,4-diisocyanate, 4. 4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1°2-diisocyanate,
Diisocyanates such as cyclohexylene-1°2-diisocyanate and cyclohexylene-1°4-diisocyanate; triisocyanates such as 4°4°, 4”-triphenylmethane triisocyanate and toluene-2,4,6-triisocyanate; 4.4-) Tetraisocyanates such as dimethyldiphenylmethane-2,2°,5,5”-tetraisocyanate, adducts of hexamethylene diisocyanate and trimethylolpropane, 2.4-) adducts of lylene diisocyanate and trimethylolpropane , an adduct of xylylene diisocyanate and trimethylolpropane, an adduct of tolylene diisocyanate and hexanetriol, and the like can be used.

On the other hand, the polyol that is the second wall film-forming substance is
Examples include aliphatic and aromatic polyhydric alcohols, hydroxy polyesters, and hydroxy polyalkylene ethers. Preferred polyols include 2
The molecular structure has the following group (1), (II), (III) or (IV) between the hydroxyl groups, and the molecular weight is 500.
0 or less polyhydroxy compounds.

(I) C2-8 aliphatic hydrocarbon group (n)-tongue-0
-Ar-0-<1> Here, Ar in (II), (III), and (IV) represents a substituted or unsubstituted aromatic moiety, and the aliphatic hydrocarbon group in (I) is -CnH2n- has a basic skeleton, and hydrogen atoms may be substituted with other elements.

Examples of (I) include ethylene glycol, 1.3-propanediol, 1.4-butanediol, 5-bentanediol, 1.6-hexanediol, 1.7-
Hebutanediol, 1,8-octanediol, propylene glycol, 2,3-dihydroxybutane-1,2
-dihydroxybutane, 1,3-dihydroxybutane,
2.2-dimethyl-1,3-propanediol, 2.4
-bentanediol, 2,5-hexanediol, 3-
Methyl-1,5-bentanediol, 1,4-cyclohexane dimetatool, dihydroxycyclohexane, diethylene glycol, 1.2.6-trihydroxyhexane, phenylethylene glycol, 1,1.1-1-
Examples include limethylolpropane, hexanetriol, pentaerythritol, glycerin, and the like.

Examples of (n) include condensation products of aromatic polyhydric alcohols and alkylene oxides such as 1,4-di(2-hydroxyethoxy)benzene and resorcinol dihydroxyethyl ether.

Examples of (I[) include p-xylylene glycol, m
-xylylene glycol, α, α“ -dihydroxy-
Examples include p-diisopropylbenzene.

Examples of (IV) include 4.4''-dihydroxy-diphenylmethane, 2-(p,p'-dihydroxydiphenylmethyl)benzyl alcohol, adduct of bisphenol A and ethylene oxide, via, addition of phenol 8 and propylene oxide. Examples include things.

The polyol is preferably used in a ratio of 0.02 to 2 moles of hydroxyl groups per mole of isocyanate groups.

When producing microcapsules as described above, water-soluble polymers can be used. Here, water-soluble polymers include water-soluble anionic polymers, nonionic polymers, and amphoteric polymers. As anionic polymers, both natural and synthetic polymers can be used. For example, −
Examples include those having a coo-1-s03- group.

Specific anionic natural polymers include gum arabic and alginic acid, while semi-synthetic products include carboxymethyl cellulose, phthalated gelatin, sulfated starch, sulfated cellulose, and lignin sulfonic acid.

Synthetic products include maleic anhydride-based (including hydrolyzed) copolymers, acrylic acid-based (including methacrylic acid-based) polymers and copolymers, vinylbenzenesulfonic acid-based polymers and copolymers, Examples include carboxy-modified polyvinyl alcohol.

Examples of nonionic polymers include polyvinyl alcohol, hydroxyethyl cellulose, and methyl cellulose.

Examples of amphoteric compounds include gelatin.

These water-soluble polymers are used as a 0.01 to 10% by weight water-soluble liquid.

When making microcapsules, they can be made from an emulsion containing 0.2% by weight or more of the component to be microencapsulated.

As mentioned above, the microcapsules produced as described above are destroyed by heat and pressure, such as those used in conventional recording materials, and react with the reactive substance contained in the core of the microcapsules and the outside of the microcapsules. This method does not cause a coloring reaction by bringing a reactive substance into contact with the reactive substance (it mainly permeates the microcapsule wall and causes a reaction by heating the reactive substance present in the core and outside of the microcapsule). In this case, if a compound that lowers the glass transition point of the wall material is contained in the recording layer in order to promote softening of the wall of the microcapsule during heating and make it easier for the reactant to pass through, the color development temperature may be lowered. can be substantially reduced.

Such a glass transition point regulating agent is preferably one that lowers the glass transition point of the wall material of the microcapsules to 80 to 150°C, particularly one that lowers it to 100 to 130°C.
Specific examples include hydroxy compounds, carbamate ester compounds, aromatic methoxy compounds, and the like.

Some of these compounds not only lower the glass transition point of the microcapsule wall material, but also lower the melting points of coupling components and basic substances. This is particularly effective as the temperature is further reduced.

These compounds are introduced into the recording layer in the same way as basic substances.

The heat-sensitive recording material of the present invention contains silica, barium sulfate, titanium oxide, aluminum hydroxide, zinc oxide,
Pigments such as calcium carbonate, fine powders such as styrene beads and urea-melamine resin can be added.

Similarly, metal stones m can also be added to prevent sticking. The amount used is 0.2-7g
/rrf.

Furthermore, a heat-melting substance can be added to the heat-sensitive recording material of the present invention in order to increase the heat recording speed. Such thermofusible substances are solid at room temperature, but melt when heated with a thermal head, and have a melting point of 50°C to 150°C.
It is a substance that dissolves diazo compounds, coupling agents, or basic substances. 0.1 for thermofusible substances
Dispersed in ~10μ particles, solid content 0.2~7g/r
used in the amount of rl. Specific examples of heat-melting substances include fatty acid amides, N-substituted fatty acid amides, ketone compounds,
Examples include N-substituted carbamate compounds, urea compounds, and esters.

Substances not contained in microcapsules are preferably used after being dispersed in solid form using a sand mill or the like. In this case, they are each dispersed separately or simultaneously in an aqueous polymer solution.

Preferred water-soluble polymers include water-soluble polymers used when making microcapsules. In this case, the concentration of the water-soluble polymer is 2 to 30% by weight, and the amount of the substance dispersed in this water-soluble polymer solution is 5 to 40% by weight.
It is invested so that it becomes. The dispersed particle size is 10
It is preferably less than μ.

The heat-sensitive recording material of the present invention can be coated using a light-transmitting binder.

Binders include polyvinyl alcohol, methylcellulose, carboxymethylcellulose, hydroxypropylcellulose, gum arabic, gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic acid ester, ethylene-vinyl acetate, etc. Various emulsions such as polymers can be used. The amount used is 0.5-5 g/cd as solid content.

In the present invention, in addition to the above materials, citric acid is used as an acid stabilizer.
Tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid, etc. can be added.

The heat-sensitive recording material of the present invention is prepared by preparing a coating liquid by dispersing microcapsules containing a diazo compound and an organic solvent and other components in a solid state (which can also be microcapsulated) or by melting them as an aqueous solution and then mixing them. , coated on a support such as paper or synthetic resin film by a coating method such as bar coating, blade coating, air knife coating, gravure coating, roll coating, spray coating, dip coating, etc., and dried to a solid content of 2.5. Produced by providing a heat sensitive layer of ~15 g/rrf.

The paper used for the support is a thermally extracted paper sized with a neutral sizing agent such as an alkyl ketene dimer.
The use of neutral paper No. 6 to No. 9 (described in JP-A-55-14281) is advantageous in terms of storage stability over time.

In addition, in order to prevent the coating liquid from penetrating the paper and improve the contact between the recording heat head and the heat-sensitive recording layer, Japanese Patent Application Laid-Open No. 57-1166
The paper described in No. 87 and having a Bekk smoothness of 90 seconds or more is advantageous.

Also, paper with an optical surface roughness of 8μ or less as described in JP-A No. 58-136492, and paper with a density of 9.9 g/cm3 or less and an optical contact ratio of 15% or more as described in JP-A-58-69091. , a paper made from pulp beaten to 400 cc or more with a Canadian standard freeness (JIS P812 L) described in JP-A-58-69097, which prevents the penetration of coating liquid, JP-A-58-65695 JP-A-59-35, which improves the color density and resolution by using the glossy side of base paper made by a Yankee machine as the coating surface, as described in No.
Papers described in No. 985, in which base paper is subjected to corona discharge treatment to improve coating suitability, can also be used in the present invention and give good results. In addition to these, any support commonly used in the field of heat-sensitive recording paper can be used as the support of the present invention.

The heat-sensitive recording material of the present invention can be used as printer paper for facsimile machines and electronic computers that require high-speed recording, and can be fixed by exposing it to light after printing by heating to decompose unreacted color formers. . In addition, it can also be used as a heat-developable copying paper.

(Effects of the Invention) Since the heat-sensitive recording material of the present invention has at least a diazo compound microencapsulated, the recording material has good shelf life, and a polymerizable compound having an ethylenically unsaturated bond can be added to the diazo compound. Because of this, there is no background staining when photofixing is performed, and the recorded image can be stored in good condition after recording.

It goes without saying that these effects of the present invention can be similarly obtained in multicolor thermosensitive recording materials using one or more color formers.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Note that "part j" indicating the amount added represents "part by weight."

Example 1 4 parts of the following diazo compound and 18 parts of a (3:1) adduct of xylylene diisocyanate and trimethylolpropane were added to a mixed solvent of 6 parts of tricresyl phosphate, 18 parts of trimethylolpropane trimethacrylate, and 6 parts of dichloromethane. and dissolved.

This diazo compound solution was mixed with polyvinyl alcohol 5.
2 parts dissolved in 58 parts water;
The mixture was emulsified and dispersed at ℃ to obtain an emulsion having an average particle size of 2.5μ. 100 parts of water was added to the obtained emulsion and heated to 60° C. with stirring, and after 2 hours, a capsule liquid containing a diazo compound in the core material was obtained.

(Diazo compound) C4H9 C4H9 Next, 10 parts of 2-hydroxy-3-naphthoic acid 3°-morpholinopropylamide and 15 parts of p-benzyloxyphenol were added to 100 parts of a 5% polyvinyl alcohol aqueous solution, and dispersed in a sand mill for about 24 hours. and average particle size 2μ
A dispersion of the coupling component and p-hensyloxyphenol was obtained.

Capsule liquid of diazo compound obtained as above 5
36 parts of a dispersion of a coupling component and p-benzyloxyphenol were added to 0 parts to prepare a coating liquid. This coating solution was coated on smooth high-quality paper (50 g/rrr) using coach-in-blonde to give a dry weight of 10 g/rrr, and dried at 40° C. for 30 minutes to obtain a heat-sensitive recording material.

Gm mode (Hifax 7) was applied to the obtained heat-sensitive recording material.
00; Hitachi, Ltd. side layer), and then the entire surface was exposed to light using Ricoh Super Dry 100 (manufactured by Ricoh @) and fixed. The blue density of the obtained recorded image was measured using a Macbeth reflection densitometer. Similarly, the yellow density of the background was measured. The results are shown in Table 1.

On the other hand, when thermal recording was performed again on the fixed portions, no image was recorded on any of them, and it was confirmed that they were fixed.

Next, in order to examine raw storage stability, we examined the skin density (capri) of the heat-sensitive recording material and the heat-sensitive recording material at 40°C and relative humidity of 9.
Capri was stored in a dark place under 0%RH conditions for 24 hours and subjected to a forced deterioration test, then measured using a Macbeth reflection densitometer.
I saw the changes in Capri.

The results are shown in Table 1.

Example 2. ~6° Except that the vinyl monomer shown in the table below was used instead of trimethylolpropane trimethacrylate in Example 1,
Heat-sensitive recording materials 2 to 6 were prepared in the same manner as in Example 1, and tested in the same manner as in Example 1. The results are shown in Table 1.

Example 7 In Example 1, the following co-dispersion was used instead of the co-dispersion of the coupling component and p-benzyloxyphenol.
Made by I.

10 parts of 2-hydroxy-3-naphthoic acid anilide, 10 parts of triphenylguanidine, and 20 parts of p-benzyloxyphenol were added to 120 parts of 5% polyvinyl alcohol, and the same operation as in the example was carried out to obtain a dispersion.

A coating solution was prepared by adding 80 parts of a dispersion of a coupling component to 50 parts of a capsule of a diazo compound, and coating the solution using coach-in-blonde to give a dry weight of 11 g/nf to obtain a heat-sensitive recording material. Ta.

Comparative Example 1 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that trimethylolpropane trimethacrylate was omitted and 24 parts of tricresyl phosphate was used instead.

The test results are shown in Table 1.

Comparative Example 2 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that trimethylolpropane trimethacrylate and tricresyl phosphate were omitted and 24 parts of dibutyl phthalate was used instead. The test results are shown in Table 1.

As is clear from Table 1, the yellow density of the background part of Comparative Examples 1 and 2 is quite high, whereas the yellow density of Examples 1 to 7 of the present invention is low, and the heat-sensitive material manufactured by the present invention Proven to be excellent.

Claims (1)

[Claims] In a heat-sensitive recording material provided with a recording layer containing at least a diazo compound and a coupling component on a support,
A heat-sensitive recording material characterized in that the diazo compound is contained in microcapsules together with a polymerizable compound having an ethylenically unsaturated bond.