JP2597177B2 - Thermal recording material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat-sensitive recording material, and more particularly to a diazo-based heat-sensitive recording material.

"Prior art" A leuco coloring type thermosensitive recording material is usually used as a recording material used in a thermosensitive recording method. However,
This heat-sensitive recording material has a drawback that coloring occurs in unexpected places due to severe handling, heating or adhesion of a solvent after recording, and the recorded image is stained. In recent years, diazo-based heat-sensitive recording materials have been actively studied as heat-sensitive recording materials free from such defects. For example, JP-A-57-123086
No., Journal of the Institute of Image Electronics Engineers of Japan, 11, 290 (1982), etc., but the description of materials using a diazo compound, a coupling component, and a basic component (including a substance that becomes basic by heat) is also made. Recording is performed, and then light irradiation is performed to decompose unreacted diazo compounds to stop color development. Certainly, according to this method, it is possible to stop coloring (hereinafter, referred to as “fixing”) of a portion that does not require recording.

In order to prevent pre-coupling during storage, at least one of the components relating to the coloring reaction is contained in the core material of the diazo-based thermosensitive recording material, and a wall is formed around the core material by polymerization. A heat-sensitive recording material using the obtained microcapsules is described in JP-A-59-190886.

However, even in these diazo-based heat-sensitive recording materials, it is desired to impart higher color developability, improve raw storability, improve light fastness of recorded images, and the like. With the expansion of use of recording materials, it is necessary to maintain high quality of recorded images for a long period of time. For this reason, it is desired to further reduce the coloring of the background after fixing even in the fixing type.

"Problems to be Solved by the Invention" It is therefore an object of the present invention to provide a heat-sensitive recording material having high coloring properties, excellent raw storage properties and excellent image fastness, and having less coloring of the background after fixing.

"Means for Solving the Problems" An object of the present invention is to provide a diazo compound, a coupling component that couples with the diazo compound to form a color, and contains This was achieved by a heat-sensitive recording material characterized in that a heat-sensitive recording layer containing a basic substance having a partial structure represented by the formula (1) was coated on a support.

As the basic substance of the present invention, the melting point is 60 ° C or more and 200 ° C.
The following is preferable, and more preferably 80 ° C. or more
It has a melting point of 140 ° C or less.

In addition, the basic substance of the present invention is preferably hardly soluble in water in order to reduce pre-coupling during storage, and is preferably excellent in compatibility with the coupling component in order to improve color development.

As the basic substance of the present invention, those represented by the following general formula (II) are preferable.

In the formula, R ₃ and R ₄ represent a substituted or unsubstituted alkyl group, aryl group, or aralkyl group.

More preferably, they contain an ether bond or a thioether bond as shown in the following general formula (III).

In the formula, X represents O or S, and Ar ₁ and Ar _{2 each} represent a substituted or unsubstituted phenyl group or naphthyl group.

Further, among the basic substances of the present invention, those having a structure represented by the following general formula (IV) are also suitable.

In the formula, X is O or S, Ar ₃ is a substituted or unsubstituted phenyl group or naphthyl group, R ₅ and R ₆ are a substituted or unsubstituted alkyl group or an aralkyl group, and R ₅ and R ₆ are each other May be linked to form a ring. In that case, other hetero atoms may be included in the connecting ring. Specific examples of the preferred hetero ring include a morpholine ring and a piperazine ring.

Alkyl groups, aryl groups or aralkyl groups represented by R ₃ , R ₄ , R ₅ and R ₆ in the general formulas (II) to (IV), and Ar
Examples of substituents of a phenyl group or a naphthyl group represented by ₁ , Ar ₂ and Ar ₃ include an alkyl group, an alkoxy group, an alkylthio group, a halogen atom, an alkoxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an ureido group, and a cyano group. Group, acylamino group and the like.

 Preferred compounds are as follows.

1) N, N'-bis (3-phenoxy-2-hydroxypropyl) piperazine 2) N, N'-bis [3- (p-methylphenoxy) -2
-Hydroxypropyl] piperazine 3) N, N'-bis [3- (p-methoxyphenoxy)-
2-hydroxypropyl] piperazine 4) N, N'-bis (3-phenylthio-2-hydroxypropyl) piperazine 5) N, N'-bis [3- (β-naphthoxy) -2-hydroxypropyl] piperazine 6) N-3- (β-naphthoxy) -2-hydroxypropyl-N′-methylpiperazine 7) N- [3- (β-naphthoxy) -2-hydroxy]
Propylmorpholine 8) 1,4-bis [(3-morpholino-2-hydroxy)
Propyloxy] benzene 9) 1,3-bis [(3-morpholino-2-hydroxy)
Propyloxy] benzene 10) 1,4-bis {[(3- (N-methylpiperazino)-
2-Hydroxy] propyloxydibenzene It goes without saying that the invention is not limited to these examples. Two or more of these may be used in combination, or a known water-insoluble or water-insoluble basic substance or a substance that generates an alkali by heating may be used in combination. It is effective that the content of these known substances with respect to the basic substance of the present invention is 60% or less, particularly 10 to 50%.

Preferred compounds among these known basic substances include guanidines, imidazolines, amidines and the like.

The diazo compound used in the present invention has the general formula ArN ₂ ⁺ X ⁻
(Wherein, Ar represents an aromatic moiety, N ₂ ⁺ represents a diazonium group, and X ⁻ represents an acid anion). A compound that can form a color by causing a coupling reaction with a coupling component and can be decomposed by light.

Specifically, the aromatic moiety preferably has the following general formula.

In the formula, Y is a hydrogen atom, a substituted amino group, an alkoxy group,
R represents a hydrogen atom, an alkyl group, an alkoxy group, an aryloxy group, an arylamino group, or a halogen (I, Br, Cl, F), and represents an aryloxy group, an arylthio group, an alkylthio group, or an acylamino group. n represents 1 or 2.

As the substituted amino group for Y, a monoalkylamino group,
Dialkylamino, arylamino, morpholino, piperidino, pyrrolidino and the like are preferred.

Specific examples of the salt-forming diazonium include 4-diazo-1-dimethylaminobenzene and 4-diazo-1-
Diethylaminobenzene, 4-diazo-1-dipropylaminobenzene, 4-diazo-1-methylbenzylaminobenzene, 4-diazo-1-dibenzylaminobenzene, 4-diazo-1-ethylhydroxyethylaminobenzene, 4- Diazo-1-diethylamino-3-methoxybenzene, 4-diazo-1-dimethylamino-2-methylbenzene, 4-diazo-1-benzoylamino-2,
5-diethoxybenzene, 4-diazo-1-morpholinobenzene, 4-diazo-1-morpholino-2,5-diethoxybenzene, 4-diazo-1-morpholino-2,5-dibutoxybenzene, 4-diazo -1-anilinobenzene, 4-diazo-1-toluylmercapto-2,5-diethoxybenzene, 4-diazo-1,4-methoxybenzoylamino-2,5-diethoxybenzene, 4-diazo-1
-Pyrrolidino-2-ethylbenzene and the like.

Specific examples of the acid anion include CnF _{2n + 1} COO ⁻ (n is 3
To 9), CmF _{2m + 1} SO ₃ ⁻ (m is an integer of 2 to 8), (C
_{lF 2l + 1 SO 2) 2} CH - (l 1 to 18 integer), Other, ZnCl ₃ ^-, BF ₄ ^-, PF ₆ ^-, and the like.

In particular, as the acid anion, those containing a perfluoroalkyl group or a perfluoroalkenyl group or PF ₆ ^- are preferable since they do not increase fog during raw storage.

Specific examples of the diazo compound (diazonium group) include:
For example, the following examples are given.

The coupling component used in the present invention is one that couples with a diazo compound (diazonium salt) in a basic atmosphere to form a dye. Specific examples thereof include resorcinol, phloroglucin, 2,3-dihydroxynaphthalene-6-sulfonic acid. Sodium, 1-hydroxy-2-
Naphthoic acid morpholinopropylamide, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-
Dihydroxy-6-naphthalenesulfonic acid anilide-2
-Hydroxy-3-naphthoic acid morpholinopropylamide, 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 tetradecylamide, acetanilide, acetoacetanilide,
Benzoylacetanilide, 1-phenyl-3-methyl-5-pyrazolone, 1- (2 ', 4', 6'-trichlorophenyl) -3-benzamide-5-pyrazolone, 1-
(2 ', 4', 6'-Trichlorophenyl) -3-anilino-5-pyrazolone, 1-phenyl-3-phenylacetamido-5-pyrazolone and the like. Further, by using two or more of these coupling components, an image having an arbitrary color tone can be obtained.

In the present invention, if necessary, an aromatic ether or ester, an alcohol, a phenol, a sulfonamide, and an acid amide may be further contained in the color-forming layer to improve the raw preservability. ,
It is preferable from the viewpoint of improving the thermal coloring property and reducing the decrease in the optical density of the recorded image due to long-term storage after thermal recording.

The aromatic ether is represented by Ar-OR, and specific examples are 1) 2-benzyloxynaphthalene 2) 1-p-biphenyloxy-2-phenylethane 3) 2-p-chlorobenzyloxynaphthalene 4) 1, 2-diphenoxyethane 5) 1-phenoxy-2-p-chlorophenoxyethane 6) p-biphenyl-β-methoxyethyl ether 7) p-biphenyl-β-cyclohexyloxyethyl ether.

As ester compounds Or Represented by, R ₁ and R ₂ or R ₃ and R ₄ may be the same or different, a hydrogen atom, an alkyl group, an alkoxy group, an aryloxy group, an acyl group, a halogen atom, a cyano group, an aryl group, Represents an alkyloxycarbonyl group or an aryloxycarbonyl group. R ₁ and R ₂ or R ₃ and R ₄ may be linked to form a ring.

Among the substituents represented by R, an alkoxy group, an aryloxy group, an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom or an aryl group, or an alkyl group, an alkoxy group, a hydroxy group or a halogen atom An aryl group having 6 to 12 carbon atoms which may be substituted is particularly preferred.

To be specific, 1) 2-benzoyloxynaphthalene 2) 1,2-bis (β-phenoxyethoxycarbonyl)
Ethane 3) 1,4-bis (β-phenoxyethoxycarbonyl)
Butane 4) 1-p-methylbenzoyloxy-2-p-biphenyloxyethane 5) 1-hydroxy-2-phenoxycarbonylnaphthalene and the like.

 Examples of the alcohol include the following.

R-OH In the above formula, R is an alkyl group which may have a substituent, and may be linear, branched or cyclic or unsaturated, and may be a halogen atom, an acyl group, an alkoxy group,
It may be substituted with one or more of a hydroxy group, an aryl group, an aryloxy group, an alkoxycarbonyl group, an acylamino group, a cyano group, a nitro group and an acyloxy group.

Specific examples include 1) p-xylenol, 2) m-
Xylenol, 3) hydroxybenzyl alcohol,
4) hydroxyphenethyl alcohol, 5) p-methoxyphenoxyethanol, 6) perhydrobisphenol A, 7) naphthylene diol, 8) methyl xylylene diol, 9) methoxy xylylene diol.

The phenols are represented by Ar-OH, and specifically, 1) p-
t-butyl phenol, 2) pt-octyl phenol, 3) p-α-cumyl phenol, 4) pt-pentyl phenol, 5) 2,5-dimethylphenol, 6)
2,4,5-trimethylphenol, 7) 3-methyl-4-
Isopropylphenol, 8) p-benzylphenol, 9) o-cyclohexylphenol, 10) p- (diphenylmethyl) phenol, 11) p-benzyloxyphenol-1,2,6-bis (hydroxymethyl) -p-
Cresol and the like.

The amides include carboxylic amides and sulfonic amides, and particularly preferred are aryl carboxylic amides and aryl sulfonic amides.

Specific examples include 1) benzamide 2) ethylbenzamide 3) isopropylbenzamide 4) dimethylbenzamide 5) chlorobenzamide 6) methoxybenzamide and the like. ) Ethylbenzenesulfonamide 2) o-toluenesulfonamide 3) o-methoxybenzenesulfonamide 4) chlorobenzenesulfonamide 5) ethoxybenzenesulfonamide 6) p-toluenesulfonamide and the like. In the case of using a microencapsulation method, the core substance of the microcapsule is dissolved or dispersed in a water-insoluble organic solvent, and after emulsification, a microcapsule wall is formed around the core substance. Boiling point of 80 ° C or higher Preferred. Specifically, phosphoric acid esters, phthalic acid esters, other carboxylic acid esters, fatty acid amides, alkylated biphenyls, alkylated terphenyls, chlorinated paraffins, alkylated naphthalenes, diarylethanes and the like are used.
Specific examples include tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, tricyclohexyl phosphate, dibutyl phthalate, dioctyl phthalate, dilauryl phthalate, dicyclohexyl phthalate, butyl oleate, diethylene glycol dibenzoate, dioctyl sebacate , Dibutyl sebacate, dioctyl adipate, trioctyl trimellitate, acetyl triethyl citrate, octyl maleate, dibutyl maleate, isopropyl biphenyl, isoamyl biphenyl,
Chlorinated paraffin, diisopropyl naphthalene, 1,1 '
-Ditolylethane, 2,4-ditertiaryaminophenol, N, N-dibutyl-2-butoxy-5-tertiaryoctylaniline and the like.

Among these, dibutyl phthalate, tricresyl phosphate, diethyl phthalate, dibutyl maleate and the like can be mentioned.

Microcapsules are made by emulsifying a core material containing a reactive material and then forming a wall of a polymer material around the oil droplets. The reactant that forms the polymeric substance is added inside the oil droplet and / or outside the oil droplet. Specific examples of the polymer substance include polyurethane, polyurea, polyamide, polyester, polycarbonate, urea-formaldehyde resin, melamine resin, polystyrene, styrene methacrylate copolymer, styrene-acrylate copolymer, gelatin, polyvinylpyrrolidone, and polyvinyl alcohol. Is mentioned.

Two or more polymer substances can be used in combination. Preferred polymeric substances are polyurethanes, polyureas, polyamides, polyesters, polycarbonates, more preferably polyurethanes and polyureas.

As a method of forming the microcapsule wall, particularly when a microencapsulation method by polymerization of a reactant from inside the oil droplet is used, the effect is large. That is, within a short time,
Capsules having a uniform particle size and preferable as a recording material having excellent raw preservability can be obtained.

This technique and specific examples of compounds are described in U.S. Patent
Nos. 3,726,804 and 3,796,669.

For example, when polyurethane is used as a capsule wall material, a polyvalent isocyanate and a second substance (e.g., polyol) which reacts with the polyisocyanate to form a capsule wall are mixed in an oily liquid to be encapsulated, emulsified and dispersed in water, and then the temperature is lowered. By ascending, a polymer-forming reaction occurs at the oil droplet interface to form a microcapsule wall.

In this case, the polyisocyanate used and the polyol and polyamine to be reacted therewith are described in U.S. Pat. Nos. 3,281,383, 3,773,695, 3,793,268, Japanese Patent Publication Nos.
And JP-A-48-84086, which can also be used.

 Further, tin salt or the like can be used in combination.

In particular, a polyvalent isocyanate is used as the first wall film forming substance,
It is preferable to use a polyol as the second wall-film-forming substance because of good raw preservability. Further, by combining the two, the heat permeability of the reactive substance can be arbitrarily changed.

Examples of the polyvalent isocyanate that is the first wall film forming substance include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, and naphthalene-1,4. -Diisocyanate, diphenylmethane-4,4'-
Diisocyanate, 3,3'-dimethoxy-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, cyclohexylene-1,2-diisocyanate, cyclohexylene-1, Diisocyanates such as 4-diisocyanate, 4,
Triisocyanates such as 4 ', 4 "-triphenylmethane triisocyanate, toluene-2,4,6-triisocyanate, 4,4'-dimethyldiphenylmethane-2,
Tetraisocyanate such as 2 ', 5,5'-tetraisocyanate, adduct of hexamethylene diisocyanate and trimethylolpropane, adduct of 2,4-tolylenediisocyanate and trimethylolpropane, addition of xylylenediisocyanate and trimethylolpropane Stuff,
There are isocyanate prepolymers such as adducts of tolylene diisocyanate and hexanetriol.

Examples of the polyol as the second wall film forming substance include aliphatic and aromatic polyhydric alcohols, hydroxypolyesters, and hydroxypolyalkylene ethers. Examples of preferred polyols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,
1,7-heptanedinol, 1,8-octanediol, propylene glycol, 2,3-dihydroxybutane, 1,2-dihydroxybutane, 1,3-dihydroxybutane, 2,2-dimethyl-1,3-propane Diol, 2,4-pentanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, dihydroxycyclohexane, diethylene glycol, 1,2,
Aromatics such as 6-trihydroxyhexane, phenylethylene glycol, 1,1,1-trimethylolpropane, hexanetriol, pentaerythritol, glycerin, 1,4-di (2-hydroxyethoxy) benzene, resorcinol dihydroxyethyl ether Condensation product of polyhydric alcohol and alkylene oxide, p-xylylene glycol, m-xylylene glycol, α, α'-
Dihydroxy-p-diisopropylbenzene and the like.

Further, 4,4'-dihydroxy-diphenylmethane,
Examples thereof include 2- (p, p'-dihydroxydiphenylmethyl) benzyl alcohol, an adduct of ethylene oxide with bisphenol A, and an adduct of propylene oxide with bisphenol A. The polyol is preferably used in a ratio of hydroxyl group to isocyanate group / mol of 0.02 to 2 mol.

When making microcapsules, a water-soluble polymer can be used, but the water-soluble polymer may be any of a water-soluble anionic polymer, a nonionic polymer, and an amphoteric polymer. As the anionic polymer, either a natural polymer or a synthetic polymer can be used, and examples thereof include polymers having a —COO ⁻ , —SO ₃ ⁻¹ group, or the like. Specific anionic natural polymers include gum arabic and alginic acid, and semi-synthetic products include carboxymethyl cellulose, phthalated gelatin, sulfated starch, sulfated cellulose,
Lignin sulfonic acid and the like.

As synthetic products, maleic anhydride-based (including hydrolyzed) copolymers, acrylic acid-based (including methacrylic acid-based) polymers and copolymers, vinylbenzenesulfonic acid-based polymers and copolymers, Carboxy-modified polyvinyl alcohol and the like.

As the nonionic polymer, polyvinyl alcohol,
Examples include hydroxyethyl cellulose and methyl cellulose.

 Examples of the amphoteric compound include gelatin.

These water-soluble polymers are used as a 0.01 to 10% by weight aqueous solution. The particle size of the microcapsules is adjusted to 20 μ or less. Generally, when the particle size exceeds 20 μm, the print quality tends to be inferior.

In particular, when heating with a thermal head is performed from the coating layer side, the thickness is preferably 8 μm or less to avoid pressure fog.

As the diazo compound, coupling component or basic substance, which is the main component used in the present invention, one of them is used as the core substance of the microcapsule, or two or three kinds are used. Can be done.
When two kinds are contained in the core material of the microcapsule,
The same microcapsules or different microcapsules may be used. When three kinds are contained in the core material of the microcapsule, three kinds cannot be contained simultaneously in the same microcapsule, but there are various combinations. Other components not contained in the core material of the microcapsule are used in the heat-sensitive layer outside the microcapsule.

The compound of the present invention may be on or outside the core of the microcapsule.

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

The diazo compound, the coupling component, and / or the basic substance used in the present invention may be contained in the inside of the microcapsule or in the heat-sensitive layer outside the microcapsule, based on 1 part by weight of the diazo compound. It is preferable to use 0.1 to 10 parts by weight of the coupling component and 0.1 to 20 parts by weight of the basic substance. The diazo compound is preferably applied at 0.05 to 5.0 g / m ² .

When the diazo compound, the coupling component, and the basic substance used in the present invention are not microencapsulated, they are preferably used as a solid dispersion with a water-soluble polymer by a sand mill or the like. Preferred water-soluble polymers include water-soluble polymers used for making microcapsules. At this time, the concentration of the water-soluble polymer is 2 to 30 wt%,
The diazo compound, the coupling component, and the basic substance are added to the water-soluble polymer solution at 5 to 40% by weight, respectively.

 The size of the dispersed particles is preferably 10 μm or less.

Needless to say, the heat-sensitive recording layer of the present invention may be formed of a single layer, or may be formed of multiple layers such as a diazo layer and a coupling component layer.

To the heat-sensitive recording material of the present invention, a carbamyl acid ester compound or an aromatic methoxy compound can be further added for the purpose of further improving the thermal color development. These compounds are:
It is considered that the melting point of the coupling component or the basic substance is lowered, or the heat permeability of the microcapsule wall is improved, so that the practical concentration is increased.

Specific examples of the carbamate compound include N-
Examples thereof include ethyl phenylcarbamate, benzyl N-phenylcarbamate, phenethyl N-phenylcarbamate, benzylcarbamate, butylcarbamate and isopropylcarbamate. Specific examples of the aromatic methoxy compound include 2-methoxybenzoic acid, 3,5-dimethoxyphenylacetic acid, 2-methoxynaphthalene, 1,3,
5-trimethoxybenzene, p-benzyloxymethoxybenzene and the like can be mentioned.

In each case, the amount used is from 0.01 to 10 parts by weight, preferably from 0.1 to 5 parts by weight, based on 1 part by weight of the coupling component, but may be appropriately selected in order to adjust to a desired color density.

To the heat-sensitive recording material of the present invention, a free radical generator (a compound capable of generating free radicals by irradiation with light) used in a photopolymerizable composition or the like for the purpose of reducing yellowing of the background after light fixing is added. be able to. Examples of the free radical generator include aromatic ketones (for example, benzophenone, 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis (diethylamino) benzophenone, 4-methoxy-4 '(dimethylamino) benzophenone, 4,4'-dimethoxybenzophenone, 4-dimethylaminobenzophenone, 4-methoxy, 3,3'-dimethylbenzophenone, 1-hydroxycyclohexylphenylketone, 4-dimethylaminoacetophenone, 2- Methyl-1- [4- (methylthio) phenyl] -2-morpholino-propanone-1-acetophenone, benzyl), cyclic aromatic ketones (for example, fluorenone, anthrone, xanthone, thioxanthone, 2-chlorothioxanthone, 2,4 -Dimethylthioxanthone, 2,4-diethylthioxanthone, Emissions, N- ethyl acridone, benzanthrone), quinones (e.g., benzoquinone, 2,3,5-trimethyl -
6-bromobenzoquinone, 2,6-di-n-decylbenzoquinone, 1,4-naphthoquinone, 2-isopropoxy-1,4
-Naphthoquinone, 1,2-naphthoquinone, anthraquinone, 2-chloro-anthraquinone, 2-methylanthraquinone, 2-tert-butylanthraquinone, phenanthraquinone), benzoin, benzoin ethers (for example, benzoin methyl ether, benzoin ethyl ether, 2,2-dimethoxy-2-phenylacetophenone,
α-methylol benzoin methyl ether), aromatic polycyclic hydrocarbons (eg, naphthalene, anthracene, phenanthrene, pyrene), azo compounds (eg, azobisisobutyronitrile, α-azo-1-cyclohexanecarbonitrile, azo Bisvaleronitrile), organic disulfides (eg, thiuram disulfide), and acyl oxime esters (eg, benzyl- (o-ethoxycarbonyl) -α-monooxime).

The amount to be added is preferably 0.01 to 5 parts by weight of the free radical generator per 1 part by weight of the diazonium compound. More preferably, it is in the range of 0.1 to 1 part by weight.

By encapsulating the free radical generator together with the diazonium salt as a core material of the microcapsule, it is possible to reduce the yellowing of the background after the above-mentioned light fixing.

In the heat-sensitive recording material of the present invention, a polymerizable compound having an ethylenically unsaturated bond (hereinafter, referred to as a vinyl monomer) can be used for the purpose of reducing yellowing of the background after light fixing. A vinyl monomer is a compound having at least one ethylenically unsaturated bond (vinyl group, vinylidene group, etc.) in its chemical structure, and includes monomers, prepolymers, that is, dimers, trimers and other Oligomers have a chemical form such as mixtures thereof and copolymers thereof. Examples thereof include unsaturated carboxylic acids and salts thereof, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohol compounds, and amides of unsaturated carboxylic acids and aliphatic polyamine compounds.

The vinyl monomer is 0.2 parts per 1 part by weight of the diazo compound.
Used at a rate of の 20 parts by weight. Preferably, the proportion is 1 to 10 parts by weight.

The vinyl monomer is used together with the diazo compound in the core material of the microcapsule, and at this time, part or all of the organic solvent used as the solvent (or dispersion medium) of the core material can be replaced with the vinyl monomer.

When a diazo compound is contained as a core substance in the heat-sensitive recording material of the present invention, a diazo compound present in an aqueous phase and a diazo compound in an incomplete capsule are contained by adding a coupling reaction deactivator outside the microcapsules. The compound (ie, a diazo compound that is not completely blocked by the capsule wall) reacts with the coupling reaction quenching agent, and the diazo compound loses the coupling reaction (coloring reaction) ability to prevent fogging. it can.

The coupling reaction quenching agent may be any substance that reduces the coloring of the solution in which the diazo compound is dissolved, and the diazo compound is dissolved in water or an organic solvent, and the other is dissolved in water or an organic solvent. Selection can be made by adding the compound and looking at the color change of the diazo compound.

Specifically, hydroquinone, sodium bisulfite,
Examples include potassium nitrite, hypophosphorous acid, stannous chloride, formalin and the like. KHSaunders "The Aromatic
Diazo-Compounds and Their Technical Application
s ". (London) published in 1949, pages 105 to 306.

The coupling reaction quenching agent is preferably one in which the quenching agent itself is less colored and has less side effects.
More preferably, it is a water-soluble substance.

The coupling reaction quenching agent is used to such an extent that the thermal coloring reaction of the diazo compound is not hindered. Usually, the quenching agent is used in the range of 0.01 mol to 2 mol per 1 mol of the diazo compound. More preferably, it is used in the range of 0.02 mol to 1 mol.

The coupling reaction quenching agent of the present invention is dissolved in a solvent and then added to a liquid in which microcapsules containing a diazo compound are dispersed, a liquid in which a coupling component or a basic substance is dispersed, or a mixture thereof. Used. Preferably, the quenching agent is used in the form of an aqueous solution.

The heat-sensitive recording material of the present invention includes pigments such as silica, barium sulfate, titanium oxide, aluminum hydroxide, zinc oxide, and calcium carbonate, styrene beads, and urea for the purpose of preventing sticking to a heat head and improving writing properties. -Fine powders such as melamine resin can be used.

Similarly, metal soaps can be used to prevent sticking. The amount of these used is 0.2
It is a ~7g / m ^2.

Further, in the heat-sensitive recording material of the present invention, a heat-fusible substance can be used to increase the heat recording density. The heat-fusible substance is a substance having a melting point of 50 to 150 ° C. which is solid at room temperature and which is melted by heating with a thermal head, and which dissolves a diazo compound, a coupling component or a basic substance. The heat-fusible substance is used in an amount of 0.2 to 7 g / m ² as a solid content dispersed in particles of 0.1 to 10 μm. Specific examples of the heat-fusible substance include N-substituted fatty acid amides, ketone compounds, urea compounds, esters and the like.

The thermal recording material of the present invention can be coated using a suitable binder.

As a binder, polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, gum arabic,
Various types of vilatin, starch and derivatives thereof, polyvinylpyrrolidone, polystyrene, polyacrylamide, polyester, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylate, ethylene-vinyl acetate copolymer Emulsion can be used. The amount used is 0.5-5 g / m ² of solids.

In the present invention, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid as an acid stabilizer in addition to the above materials
Can be added.

The heat-sensitive recording material of the present invention is prepared by preparing a coating solution containing a diazo compound, a coupling component, a basic substance and other additives, and applying a bar coating, a blade coating, and an air knife on a support such as paper or a synthetic resin film. Coating, gravure coating, roll coating coating, spray coating, dip coating, etc. are applied and dried to obtain a solid content of 2.5 to 25 g / m ^2.
Is provided. As another method, a coating liquid is prepared by adding a coupling component, and a basic substance or other additives as a core substance of the microcapsules, or dispersing them in a solid form, or dissolving them as an aqueous solution and then mixing them. A precoat layer having a solid content of ² to 10 g / m2 is formed by coating and drying on top, and a diazo compound and other additives as main components are further added thereon as a core material of the microcapsules, or solid dispersion is performed. Alternatively, the coating solution prepared by mixing after dissolving as an aqueous solution may be coated and dried to form a laminated type provided with a coating layer having a solid content of 1 to 15 g / m ² . The lamination type thermosensitive recording material may have the lamination order reverse to the above lamination order, and the application method may be sequential application of the lamination or simultaneous application. This laminated type thermosensitive recording material can provide particularly excellent performance in long-term raw preservability.

Further, after providing an intermediate layer described in Japanese Patent Application No. 59-177669 or the like on a support, a heat-sensitive layer can be applied.

As the paper used for the support, hot extraction pH 6 sized with a neutral sizing agent such as alkyl ketene dimer
The use of neutral papers Nos. 9 to 9 (described in JP-A-55-14281) is advantageous from the viewpoint of storage stability over time.

In order to prevent the coating liquid from penetrating into the paper and to improve the contact between the recording heat head and the heat-sensitive recording layer, see JP-A-57-116687.
No. In addition, paper having a smoothness of 90 seconds or more is advantageous.

The optical surface roughness described in JP-A-58-136492 is 8
paper having a density of 0.9 g / cm ³ or less and an optical fusion rate of 15% or more described in JP-A-58-69091. Canadian Standard Water Level (J
Paper made from pulp beaten to 400 CC or more according to IS P8121) to prevent the penetration of the coating solution, JP-A-58-65695
The glossy surface of the base paper made by the Yankee machine described in No. 1 is used as the coated surface to improve the color density and resolution.
The paper described in JP-A-59-35985, in which the base paper is subjected to a corona discharge treatment to improve the coating suitability, is also used in the present invention and gives good results. Any of these other supports used in the field of ordinary thermosensitive 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 a printer paper for facsimile machines and electronic computers that require high-speed recording, and can be fixed by exposing and decomposing unreacted diazo compounds after heating and printing. .

Further, the heat-sensitive recording material of the present invention is a so-called heat-developing copy paper in which an unexposed image portion is colored by overlapping and exposing with a translucent support on which an image is recorded, and thereafter heating the entire surface. It is particularly preferred to be used. In such a heat-developable copying paper, the background portion is heated over the entire surface at the time of development. Therefore, when a known basic substance such as triphenylguanidine is used, the background portion is likely to be colored yellow. On the other hand, it has been found that the coloring is remarkably improved by using the basic substance of the present invention.

"Examples" Examples of the present invention will be described below, but it goes without saying that the present invention is not limited thereto.

Example 1 3.45 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 consisting of 6 parts of tricresyl phosphate and 5 parts of ethyl acetate, and dissolved by heating. . This diazo compound solution was mixed with an aqueous solution in which 5.2 parts of polyvinyl alcohol was dissolved in 58 parts of water, and emulsified and dispersed at 20 ° C. to obtain an average particle size.
2.5 μ of an emulsion was obtained. 100 parts of water was added to the obtained emulsion, and the mixture was heated to 60 ° C. with stirring, and after 2 hours, a capsule solution containing a diazo compound in the core substance was obtained.

Next, 10 parts of naphthol AS and 10 parts of N, N'-bis (3-phenoxy-2-hydroxypropyl) piperazine are added to 100 parts of a 5% aqueous solution of polyvinyl alcohol, and the mixture is dispersed by a sand mill for about 24 hours. I got something.

Further, 20 parts of p-benzyloxyphenol were added to 100 parts of a 4% aqueous solution of polyvinyl alcohol and 100 parts of water, and dispersed in a paint shaker for 2 hours to obtain a dispersion having an average particle size of 3 μm.

Capsule liquid of diazo compound obtained as described above
50 parts of a coupling component and 24 parts of a dispersion of a basic substance,
28 parts of a dispersion of p-benzyloxyphenol was added to prepare a coating solution. This coating solution was applied to a smooth high-quality paper (50 g / m) using a coating bar to a dry weight of 10 g / m ² and dried at 25 ° C. for 30 minutes to obtain a heat-sensitive material.

Comparative Example 1 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that N, N'-bis (3-phenoxy-2-hydroxypropyl) piperazine in Example 1 was changed to triphenylguanidine.

(Test Method) The obtained thermosensitive recording materials of Example 1 and Comparative Example 1 were used.
G III mode thermal printer (Hyfax 700;
Thermal recording was performed using Hitachi Ltd.), and the entire surface was exposed and fixed using Ricopy Super Dry 100 (Ricoh Co., Ltd.). The blue density of the obtained recorded image was measured by a Macbeth reflection densitometer. The yellow density of the background was also measured. On the other hand, when thermal recording was again performed on the fixed portion, it was confirmed that no image was recorded and the image was fixed.

Next, at 60 ° C and 30% relative humidity,
The background density (fog) of the heat-sensitive recording material when stored at 40 ° C and a relative humidity of 90% for 24 hours, and the heat-sensitive recording material was further converted to a Xenon Long Life Fade Meter (FAL-25AX / HC)
(Type: manufactured by Suga Test Instruments Co., Ltd.) for 24 hours, and after performing a forced deterioration test, the yellow density of the background was measured with a Macbeth reflection densitometer to check the change in the coloring of the background.

Next, in order to examine the decrease in the optical density of the colored portion due to long-term storage after thermal recording, the recorded image of
After storage in a dark place at 16 ° C. for 16 hours and a forced deterioration test, a case where the density of the recorded image was reduced was evaluated. The results are shown in Table 1.

Table 2 summarizes the measurement results of the coloring of the background portion.

Example 2 Next, an example of a heat-developable thermosensitive copying paper to which the present invention is particularly preferably used will be described in detail below.

3.45 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 consisting of 24 parts of tricresyl phosphate and 5 parts of ethyl acetate, and dissolved by heating. The diazo compound solution was mixed with an aqueous solution in which 5.2 parts of polyvinyl alcohol was dissolved in 58 parts of water, and emulsified and dispersed at 20 ° C. to obtain an emulsion having an average particle size of 1.5 μm. 100 parts of water was added to the obtained emulsion, and the mixture was heated to 60 ° C. with stirring, and after 2 hours, a capsule solution containing a diazo compound in the core substance was obtained.

Next, 20 parts of naphthol AS and 20 parts of N, N'-bis (3-phenoxy-2-hydroxypropyl) piperazine were added to 100 parts of a 5% aqueous solution of polyvinyl alcohol, and about 2 parts were added with a sand mill.
The mixture was dispersed for 4 hours to obtain a dispersion having an average particle size of 3 μm.

Capsule liquid of diazo compound obtained as described above
A coating solution was prepared by adding 50 parts of a coupling component and 6 parts of a dispersion of a basic substance. Apply this coating solution to smooth high quality paper (50g /
m) was applied using a coating bar to a dry weight of 6 g / m ² and dried at 25 ° C. for 30 minutes to obtain a heat-sensitive material.

Example 3 N, N'-bis (3-phenoxy-2-hydroxypropyl) piperazine of Example 2 was converted to N, N'-bis [3- (p
-Methylphenoxy) -2-hydroxypropyl] piperazine was used in the same manner as in Example 2 to obtain a heat-sensitive recording material.

Example 4 The N, N'-bis (3-phenoxy-2-hydroxypropyl) piperazine of Example 2 was converted to N, N'-bis [3- (p
-Methoxyphenoxy) -2-hydroxypropyl] piperazine was used in the same manner as in Example 2 to obtain a heat-sensitive recording material.

Example 5 The N, N'-bis (3-phenoxy-2-hydroxypropyl) piperazine of Example 2 was converted to N, N'-bis [3- (β
-Naphthoxy) -2-hydroxypropyl] piperazine was obtained in the same manner as in Example 2 to obtain a heat-sensitive recording material.

Example 6 Example 2 was repeated except that N, N'-bis (3-phenoxy-2-hydroxypropyl) piperazine of Example 2 was replaced with N, N'-bis (3-phenylthio-2-hydroxypropyl) piperazine. A heat-sensitive recording material was obtained in the same manner as described above.

Synthesis Example 1 N, N'-bis (3-phenoxy-2-hydroxypropyl) piperazine of Example 1 and Example 2 was synthesized as follows.

86 g (1 mol) of anhydrous piperazine in one three-necked flask
Was weighed, 500 ml of ethyl acetate was added, and the mixture was heated and stirred on a steam bath to dissolve anhydrous piperazine. After dropping 315 g (2.1 mol) of phenylglycidin ether in about 30 minutes, the mixture was reacted at 75 ° C. for 2 hours. After the completion of the reaction, the mixture was cooled to remove white crystals, which were washed twice with 50 ml of cooled ethyl acetate. After drying, 347 g (yield 90%) of the target compound was obtained. Melting point 91 [deg.] C.

In the above reaction, 2.1 mol (407 g) of low-cost piperazine hexahydrate was used widely instead of anhydrous piperazine, and the target compound was obtained in the same yield even when the reaction was carried out in exactly the same manner.

Synthesis Example 2 N, N'-bis [3- (p-methylphenoxy) -2-hydroxypropyl] piperazine of Example 3 was synthesized as follows.

86 g (1 mol) of anhydrous piperazine in one three-necked flask
Was weighed, and 500 ml of methanol was added to dissolve anhydrous piperazine. After 194 g (2.1 mol) of epichlorohydrin was added dropwise at room temperature for about 30 minutes, the mixture was further reacted at room temperature for 1 hour. Next, 270 g (2.5 mol) of p-cresol was added in about 30 minutes, and 100 g (2.5 mol) of sodium hydroxide was further added thereto.
The reaction was carried out at 6 ° C. for 6 hours. After completion of the reaction, the reaction mixture was cooled, and the generated white crystals were washed twice with 100 ml of a cooled mixed solvent of methanol / water (1/1). When dried, the target compound is 269
g (65% yield). 113 ° C.

Synthesis Example 3 N, N'-bis [3 of Example 4 was prepared in the same manner as in Synthesis Example 2 except that 270 g (2.5 mol) of p-cresol of Synthesis Example 2 was replaced with 310 g (2.5 mol) of p-methoxyphenol. − (P
-Methoxyphenoxy) -2-hydroxypropyl]
303 g (68% yield) of piperazine were obtained. Melting point 123
° C.

Synthesis Example 4 The procedure of Synthesis Example 2 was repeated, except that 270 g (2.5 mol) of p-cresol in Synthesis Example 2 was replaced with 360 g (2.5 mol) of β-naphthol, and the N, N′-bis [3- (Β-naphthoxy) -2-hydroxypropyl] piperazine is 292 g.
(60% yield). 176 ° C.

Synthesis Example 5 The procedure of Example 6 was repeated except that 270 g (2.5 mol) of p-cresol in Synthesis Example 2 was replaced by 275 g (2.5 mol) of thiophenol.
293 g of 2-hydroxypropyl) piperazine (yield 70
%). 85 ° C.

Comparative Example 2 A heat-sensitive recording material was obtained in the same manner as in Example 2 except that N, N'-bis (3-phenoxy-2-hydroxypropyl) piperazine of Example 2 was changed to triphenylguanidine.

(Test Method) After imagewise exposing the obtained heat-sensitive recording materials of Example 2 and Comparative Example 2 using Ricopy Super Dry 100 (manufactured by Ricoh Co., Ltd.), the entire surface was heated at 150 ° C. for 5 seconds using a hot plate. . The blue density of the obtained recorded image was measured by a Macbeth reflection densitometer. The yellow density of the background was also measured.

Next, at 60 ° C and 30% relative humidity,
The color density after storage at 40 ° C. and a relative humidity of 90% for 24 hours was measured in the same manner.

To check the light fastness of the image, the heat-sensitive recording material after recording was measured using a Xenon Long Life Fade Meter (FAL).
Light was irradiated for 24 hours with a -25AX / HC type (manufactured by Suga Test Instruments Co., Ltd.), and the image density after the forced deterioration test was measured with a Macbeth reflection densitometer. In order to check the robustness of the image against temperature and humidity, the thermosensitive recording material after recording was stored for 24 hours in a dark place at 50 ° C and 90% relative humidity, and the image density was measured after a forced deterioration test was performed. did.

Next, in order to check the coloring of the background, the xenon long life fade meter (FAL-25AX / HC type; Suga Test Instruments Co., Ltd.) was used for the heat-sensitive recording material after recording in the same way as when the light fastness of the image was examined. ) For 24 hours, and after performing a forced deterioration test, the yellow density of the ground was measured with a Magbeth recorder.

Furthermore, in order to check the coloring of the background due to the temperature and humidity after recording, the thermal recording material after recording was stored for 24 hours in a dark place at 50 ° C and 90% relative humidity, and the background after a forced deterioration test was performed. Was measured with a Macbeth reflection densitometer.

 The above results are shown in Tables 3 to 5.

From these results, the heat-sensitive recording material of the present invention has a coloring property,
It can be seen that the material is excellent in raw preservability and image fastness, and is an excellent heat-sensitive recording material with less coloring of the background.

Claims (1)

(57) [Claims] 1. A diazo compound, a coupling component which forms a color by coupling with the diazo compound, and A heat-sensitive recording material, characterized in that a heat-sensitive recording layer containing a basic substance having a partial structure represented by the formula is coated on a support.