DE3639382A1 - HEAT SENSITIVE RECORDING MATERIAL - Google Patents

Description

The invention relates to a heat-sensitive recording material, especially a heat sensitive recording material of the diazo type.

Heretofore, generally, it has become a heat sensitive recording material of the leuco dye type used. But when this material type roughly treated after recording exposed to heat or with solvents becomes contaminated occurs on unexpected, unexposed Set up discoloration, causing the recorded Images become contaminated. To solve this problem, recently became a heat sensitive recording material proposed of the diazo dye type (see, for example Japanese OPI patent application 1 23 086 / 82 (the abbreviation "OPI" used here stands for a "unexamined published patent application"), and Gazo Denshi Gakkai Shi, 11, 290 (1982)).

In this case, heat recording is carried out using a recording material that a Diazo compound, a coupling component and a basic one Component (this also includes a substance that by means of heat), which then contains light is irradiated to the remaining unreacted diazo compound decompose to stop the discoloration. After this procedure, it is certainly possible to Discoloration of the parts on which no recording is required is to stop (hereinafter referred to as "fixing" designated). However, this recording material has the Disadvantage that gradually during its storage an early clutch occurs, the one unwanted discoloration (obfuscation). Around  to solve this problem, it has been ensured that a of the coloring components in the form of intermittent Particles (solid dispersion) is present to prevent that the components come into contact with each other, and um thereby preventing the premature clutch. But also in this case the shelf life or shelf life of the recording material (hereinafter referred to as "shelf life in the raw state "designated) unsatisfactory and its thermal color-forming ability decreases.

Another known method for solving the above The problem described is a diazo compound and to provide coupling components in separate layers, to minimize the contact between the components hold (such as in the above Japanese OPI patent application 1 23 086/82 described). At This process is the shelf life in the raw state greatly improved while the thermal color-forming ability decreases sharply. The material is therefore in the Practice unusable because it relies on high speed recording, where the pulse width is narrow, cannot respond.

For a satisfactory shelf life in the raw state and a satisfactory thermal color-forming ability to achieve at the same time, it has already been proposed either the coupling components or one basic substance in capsules from a non-polar wax-like substance (see, for example, the Japanese OPI patent application 1 42 636/82) or from a high molecular weight hydrophobic substance (cf. Japanese OPI patent application 1 92 944/82), thereby encapsulating the Component versus the other components is isolated. This encapsulation process makes a difference differs from the usual encapsulation process,  in which a core substance is surrounded by a shell, because in the process a wax or a highly polymeric Substance dissolved in its solvent and a staining Component in the resulting encapsulation solution is dissolved or dispersed. The coloring Component therefore does not become a core of a capsule, but mixes evenly with the encapsulating substance. When the material so produced is stored an early clutch gradually occurs around the wall of the capsules leading to deterioration the shelf life of the material. Because a color formation reaction only begins when the wall the capsules are melted by heat, over it in addition, the thermal color-forming ability is inevitable worse. A manufacturing problem also arises in this regard on as a solvent used to dissolve the Wax or a macromolecule is used after the Formation of the capsules must be removed again.

To solve the above problems, a heat-sensitive recording material with an improved Shelf life or shelf life suggested (see Japanese OPI patent application 1 90 886/84). This method uses at least one component, the is related to a color formation reaction as Core substance enclosed and a wall is around the Core created around by a polymerization reaction Formation of a microcapsule.

The heat-sensitive recording material described above, after the microencapsulation process has been produced has the disadvantage that the recorded image after fixation with light opposite Light and heat is not stable (real) enough and that the parts free of a recording turn yellow.  Extensive investigations have therefore been carried out to overcome these drawbacks.

The aim of the invention is to provide a heat-sensitive recording material to create with the help of it possible is to fix the recorded image appropriately and to get bright white parts without recording. The aim of the invention is also a heat-sensitive To create recording material that is a thermal recorded color image with an advantageous Resistance or authenticity to light and heat after fixing. The aim of the invention is also to a heat-sensitive recording material excellent shelf life or durability in its raw state, excellent image quality and one to create excellent image stability. target Finally, the invention is a heat sensitive To create recording material that is excellent Has reproductive power.

The above objectives can be achieved according to the invention with a heat-sensitive recording material, which has a heat-sensitive layer on a support, which contains a diazonium salt and a coupler, wherein the heat sensitive layer at least one compound contains, which is selected from the group of sterically hindered phenols and their derivatives.

With the heat-sensitive recording material according to the invention it is possible to have a high image density and at the same time an excellent shelf life in the Raw state and excellent image stability after to achieve the recording. The material is suitable particularly good for the storage or storage of recorded Images for a long period of time since the  Color density of the background after fixation with light is low.

The shelf life of the heat-sensitive recording material in the raw state and the durability or Shelf life of the recorded images can go even further be improved by using at least one of the compounds who participate in color formation, a microencapsulation submits.

The heat-sensitive recording material according to the invention can be used as printing or reproduction paper for a facsimile process and an electronic computer can be used with a high recording speed is required. If the thermal Printing or reproduction is carried out, the Copy or print fixed by exposure to light , which decomposes the unreacted color former becomes. In addition, the material can be used as copy paper be used in thermal development.

The sterically hindered phenols and their derivatives used according to the invention serve to stabilize the coloring materials and color images and to prevent yellowing of the background. Preferred examples of these compounds are those of the formulas (IV) given below: in which mean:
R ₁ , R ₂ and R ₃ , which may be the same or different, each represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group or a halogen atom; among these substituents, an alkyl group, an aryl group and an alkoxy group may have other substituents; and an alkylene group or an arylene group, of which the latter two groups may have further substituents;

Examples of the compounds represented by the formula (I) are 2,6-di-tert-butyl-p-cresol, 2,6-di-tert- butylphenol, 2,4-dimethyl-tert-butylphenol and 3-tert- Butyl-4-hydroxyanisole;

Examples of compounds of the formula (II) are 2,2'-methylene-bis (4-methyl-6-tert-butylphenol), 4,4'-butylidene-bis (3-methyl-6-tert-butylphenol), 4 , 4'-methylene-bis (2,6-di-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, n-octadecyl-3- ( 3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate, pentaerythrityl tetrakis (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, bis- [2- (2-hydroxy -5-methyl-3-tert-butylbenzyl) - 4-methyl-6-tert-butylphenyl] terephthalate, 4,4'-thiobis (3-methyl-6-tert-butylphenol), 4,4-thiobis ( 2-methyl-6-tert-butylphenol) and the like. in which mean:
R and R ′, which may be the same or different, each represent a hydrogen atom or an alkyl group,
R ₃₁ , R ₃₂ , R ₃₃ and R ₃₄ , which may be the same or different, each represents a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an alkylthio group, an acylamino group, a hydroxyl group or a halogen atom;
wherein at least one of OR and OR 'may be linked to any of R ₃₁ -R ₃₄ at its o-position to form a 5- or 6-membered ring and at least one pair of R ₃₁ -R ₃₄ which can be in the o-position to each other, can be connected to form a 5- or 6-membered ring.

Further detailed investigations of the compounds of formula (III) showed the following: R and R ′ can be the same or different and each represents a straight-chain, a branched-chain or a cyclic alkyl group with 1 to 20 carbon atoms (such as methyl -, ethyl, propyl, n-butyl, i-butyl, n-octyl, n-dodecyl, n-hexadecyl and cyclohexyl groups and the like), R ₃₁ , R ₃₂ , R ₃₃ and R ₃₄ can be identical or different from one another and each represents a hydrogen atom, a straight-chain, a branched-chain or a cyclic alkyl group having 1 to 20 carbon atoms (such as, for example, methyl, ethyl, t-butyl, t-hexyl, t-octyl, sec-docedyl, n-hexadecyl and cyclohexyl groups and the like), an aryl group having 6 to 20 carbon atoms (such as phenyl and naphthyl groups and the like), an alkoxy group having 1 to 20 carbon atoms ( such as methoxy, ethoxy, n-butoxy, i-butoxy, n-octyloxy and n-hexadecyloxy groups and the like), an alkylthio group having 1 to 20 carbon atoms (e.g. Methylthio, n-butylthio and n-octylthio groups and the like.) And an acylamino group having 1 to 20 carbon atoms (such as acetylamino and propionylamino groups and the like), a hydroxyl group and a halogen atom (such as A chlorine and bromine atom and the like).

At least one of the residues OR and OR 'can be connected to one of the residues R ₃₁ -R ₃₄ , which are in the o-position to one another, to form a 5- or 6-membered ring (e.g. a chroman, spirochroman, and Coumaran ring and the like). At least one pair of the radicals R ₃₁ -R ₃₄ , which are in the o-position to one another, can also be connected to one another to form a 5- or 6-membered ring (such as, for example, an aliphatic ring, a hetero ring, an aromatic ring) and a spiro ring and the like.).

Among the radicals R, R ', R ₃₁ , R ₃₂ , R ₃₃ and R ₃₄ , those which partially contain an alkyl group or an aryl group may be further substituted by substituents. Suitable substituents are alkyl, aryl, alkoxy, aryloxy, alkylthio, arylthio, acyl, acylamino, hydroxyl, cyano, alkoxycarbonyl, carbamoyl, sulfamoyl, acyloxy and nitro groups and a halogen atom and the like

Among the compounds of the formula (III), preference is also given to those in which OR ′ is in an o- or p-position, based on OR, and compounds of the formulas (IIIa), (IIIb), (IIIc), (IIId) and (IIIe) are particularly preferred:

R, R ', R ₃₁ , R ₃₃ and R _{34 of} the compounds of the formulas (IIIa) to (IIIe) have the same meanings as given in the formula (III). R ₃₅ , R ₃₆ , R ₃₇ , R ₃₈ , R ₃₉ and R ₄₀ may be the same or different and each represent a hydrogen atom, an alkyl group (a straight-chain, a branched-chain or a cyclic alkyl group having 1 to 20 carbon atoms, such as, for example, B. methyl, ethyl, n-butyl, n-octyl and cyclohexyl groups and the like), an aryl group (an aryl group having 6 to 20 carbon atoms such as phenyl and naphthyl groups and the like), an alkoxy group (an alkoxy group having 1 to 20 carbon atoms such as methoxy, n-butoxy and n-octyloxy groups and the like), a heterocyclic group (e.g. a morpholinyl group), an alkylamino group (an alkylamino group with 1 to 20 carbon atoms such as diethylamino, dibutylamino and n-octylamino groups and the like) and an alkoxycarbonyl group (an alkoxycarbonyl group having 1 to 20 carbon atoms such as ethoxycarbonyl and n-hexyloxycarbonyl groups).

In the practice of the invention the above compounds individually or in the form of a Combination of two or more of the same are used and they can also share with another known antifading agents can be used. Examples for known antifading agents are hydroquinones, phenols, Chromanols, coumarans, sterically hindered amines, Complexes and the like. They are, for example, in Japanese OPI patent applications 83 162/84, 24 141/83 and 1 52 225/77, in U.S. Patents 3,698,909 and 4,268,593 and in the GB-PS 20 69 162 (A) and 20 27 731 and the like. Described.  

The compounds of the formula used according to the invention (III) can be easily manufactured by a process as in US Pat. Nos. 4,360,589 and 4,273,864, in the Japanese OPI patent applications 50 244/80, 20 327/78, 77 526/78 and 10 539/84 and in the Japanese patent publication 37 856/82.

Detailed examples of the compounds of formula (III) are given below, but the invention is in no way limited to these compounds: in which mean:
R ₄₁ and R ₄₅ each represent a hydrogen atom, an alkyl group or a heterocyclic group,
R ₄₂ , R ₄₃ and R ₄₄ , which may be the same or different, each have a hydrogen atom, an alkyl, aryl, alkoxy, aryloxy, alkylthio, arylthio, acylamino, diacylamino, sulfonamide, alkylamino -, alkoxycarbonyl or acyloxy group or a halogen atom,
however, R ₄₁ and R ₄₅ cannot both be hydrogen atoms at the same time.

The compounds of formula (IV) are described in more detail below explained.

In formula (IV), R ₄₁ and R ₄₅ each represent a hydrogen atom, an alkyl group (preferably an alkyl group having not more than 20 carbon atoms, such as a straight chain or branched chain alkyl group, aralkyl group, alkenyl group, cycloalkyl group or cycloalkenyl group; such as e.g. methyl, ethyl, i-propyl, t-butyl, t-octyl, n-octyl, t-hexadecyl, benzyl, aryl, cyclopentyl and cyclohexenyl groups and the like), an aryl group (preferably an aryl group having not more than 20 carbon atoms such as phenyl, p-methylphenyl, p-methoxyphenyl, p-octanamidophenyl, o-chlorophenyl and a-naphthyl groups and the like), an alkoxy group (preferably an alkoxy group having not more than 20 carbon atoms such as methoxy, t-butoxy, cyclohexyloxy, n-dodecyloxy, n-octadecyloxy, benzyloxy and aryloxy groups and the like), an aryloxy group (preferably an aryloxy group having no more than 20 carbon atoms such as phenoxy, p-methylphenoxy, p-meth oxyphenoxy, m-chlorophenoxy and α-naphthoxy groups and the like.), an alkylthio group (preferably an alkylthio group having not more than 20 carbon atoms such as e.g. Methylthio, i-butylthio, n-hexylthio, cyclohexylthio and n-octadecylthio groups and the like.), An arylthio group (preferably an arylthio group having not more than 20 carbon atoms, such as phenylthio, p-methylphenylthio -, o-carboxyphenoxy, m-methylphenylthio, o-methoxycarbonylphenylthio and m-nitrophenylthio groups and the like), an acylamino group (preferably an acylamino group having not more than 20 carbon atoms, such as acetylamino, benzoylamino and caproamino groups and the like), a diacylamino group (preferably a diacylamino group having not more than 30 carbon atoms such as succinic acid imido and 3-hydantoinyl groups and the like), a sulfonamido group (preferably a sulfonamido group having no more than 20 carbon atoms such as e.g. Methanesulfonamido and benzenesulfonamido groups and the like.), An alkylamino group (preferably an alkylamino group having not more than 30 carbon atoms, such as ethylamino, t-butylamino, dioctylamino - and n-octadecylamino groups and the like.), an acyl group (preferably an acyl group having not more than 20 carbon atoms, such as. Acetyl, capryl and p-methoxybenzoyl groups and the like), an alkoxycarbonyl group (preferably an alkoxycarbonyl group having not more than 20 carbon atoms such as methoxycarbonyl, t-butoxycarbonyl and n-octadecyloxycarbonyl groups and the like), an acyloxy group (preferably an acyloxy group having not more than 20 carbon atoms such as acetoxy, caproxy, lauroxy and benzoyloxy groups and the like) or a halogen atom such as e.g. B. chlorine and bromine atoms and the like.). R ₃ and R ₄ are preferably both hydrogen atoms at the same time.

Among the above groups, those who contain an alkyl or aryl part, by substituents be further substituted. Examples of such substituents are partly in the above definition of Formula (IV) described and include, for example Alkyl, cycloalkyl, alkenyl, aryl, benzyl, nitro, Cyano, hydroxyl, alkyloxy, cycloalkyloxy, alkenyloxy Aryloxy, benzyloxy, alkylthio, arylthio, aminoalkylamino, Acylamino, sulfonamido, alkoxycarbonyl, silyl, Acyl, acyloxy, sulfamoyl and sulfonyl groups, halogen atoms and the like

Among the compounds of the formula (IV), those of the formulas (IVa) given below are particularly preferred in view of the effect of the present invention:

In the above formula, R ₄₆ and R ₄₇ each represent a hydrogen atom or an alkyl group, and they cannot both be hydrogen atoms at the same time.

Representative examples of compounds of formula (IV) are given below. However, the invention is in no way limited to the use of these compounds:

The compounds of formula (IV) can by the method be produced as it is in US Pat. No. 4,264,720) is described.

In practicing the invention, they can be used singly or in the form of a combination of two or more of them, as well as together with the above-mentioned antifading agents. in which mean:
R is a substituted or unsubstituted 4-piperidyl group, preferably a group of the formula wherein R ₅₁ represents a substituted or unsubstituted alkyl group (such as methyl, propyl, methoxyethyl, hydroxyethyl and the like), a substituted or unsubstituted alkenyl group (such as vinyl, aryl and the like), a substituted or an unsubstituted alkynyl group (such as ethynyl, propargyl and the like), a substituted or unsubstituted aralkyl group (such as benzyl, p-methoxybenzyl, phenethyl and the like) or a substituted or unsubstituted acyl group (such as e.g. Acetyl, chloroacetyl, acryloyl, methacryloyl, crotonoyl and the like.) And
R ₅₂ represents a hydrogen atom or more than one alkyl group (such as methyl, ethyl, chloromethyl and the like) which is a substituent on a piperidine ring; these alkyl groups can be the same or different and can be further substituted by substituents;
R _{53 represents} a hydrogen atom or more than an alkyl group (such as methyl, isopropyl, t-butyl, t-amyl, chloromethyl and the like) which is a substituent on a benzene ring; these alkyl groups can be further substituted by substituents;
Y represents a hydrogen atom or a substituted or unsubstituted alkyl group (such as butyl, dodecyl, β-methoxycarbonyl) m is the number 1 or 2 and
m + p = 2.

Among the compounds of the formula (V), those of the following formula (Va) give better effects according to the invention: wherein R ₅₁ , Y, m and p have the same meanings as in the formula (V).

Representative examples of compounds of formula (V) are given below, but the invention is by no means limited to these compounds:

The compounds of formula (V) are known compounds for example in DE-OS 24 56 364, 26 47 452, 26 54 058 and 26 56 769 and in the Japanese patent publication 20 617/82 are described, and they can by procedure are produced as described in these laid-open specifications and are explained in this patent publication.

In practicing the invention, the Connections individually or in the form of a combination of two or more of the same and also together with other known ones Antifading agents can be used.

Known antifading agents are hydroquinones, phenols, Chromanols, coumarans, sterically hindered amines, complexes and the like. For example, in Japanese OPI Patent applications 83 162/84, 24 141/83 and 1 52 225/77 and in the US-PS 36 98 909 and 42 68 593 and in the GB-PS 20 69 162 (A) and 20 27 731 and the like.

Sterically hindered phenolic compounds can take the form of fine Particles are added. If a diazonium salt or a Couplers contained in microcapsules can either can be inserted into the capsules or they can both be inside and outside the capsules. The preferred amount for that in the form of fine particles added compounds is about 0.05 to 20 parts by weight, in particular 0.2 to 5 parts by weight, per 1 part by weight of diazonium salt.

Diazo compounds are known to be diazonium salts of the general formula ArN ₂ ⁺X ^- . While they form colors (dyes) when developing a coupling reaction with a coupling component, they decompose by absorbing light (in the formula, Ar stands for an aromatic radical, N ₂ ⁺ for a diazonium group and X ^- for an acid anion). Any of these compounds can be selected in a suitable manner for the use according to the invention.

As an aromatic radical, as mentioned above, one with the following formula is advantageous: in which mean:
Y represents a hydrogen atom, a substituted amino group, an alkoxy group, an aryloxy group, an arylthio group, an alkylthio group or an acylamino group and
R represents a hydrogen atom, an alkyl group, an alkoxy group, an aryloxy group, an arylamino group or a halogen atom (such as J, Br, Cl, F).

As a substituted amino group represented by Y is a monoalkylamino, dialkylamino, arylamino, morpholino, Piperidino or pyrrolidino group and the like. Advantageously.

Examples of diazonium compounds that form salts are 4-diazo-1-dimethylaminobenzene, 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-morpholino- 2,5-diethoxybenzene, 4-diazo-1-morpholino-2,5-di- butoxybenzene, 4-diazo-1-anilinobenzene, 4-diazo-1-toluyl- mercapto-2,5-diethoxybenzene, 4-diazo-1,4-methoxybenzoylamino- 2,5-diethoxybenzene, 4-diazo-1-pyrrolidino-2-ethylbenzene and the like

Examples of an acid anion are C _n F _{2 n +1} COO ^- ( n is an integer from 3 to 9), C _m F _{2 m +1} SO ₃ ^- ( m is an integer from 2 to 8), (C _l F _{2 l +1} SO ₂ ) ₂ CH ^- ( l is an integer from 1 to 18).

Particularly preferred acid anions are those with a perfluoroalkyl group or a perfluoroalkenyl group with PF ₆ ^- , because less fogging occurs during storage (storage) in the raw state.

Detailed examples of suitable diazonium compounds (diazonium salts) are as follows:

For the coupling components that with the above Diazonium salts react to develop colors, are connections that when coupling with Diazonium salts form colors (dyes). examples for coupling components that can be used according to the invention Resorcinol, phloroglucin, 2,3-dihydronaphthalene-6-sodium sulfonate, 1-hydroxy-naphthoic acid-morpholinopropylamide, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-dihydroxy- 6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, 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- dodecyloxypropylamide, 2-hydroxy-3-naphthoic acid tetra- decylamide, acetoanilide, acetoacetoanilide, benzoylacetoanilide, 1-phenyl-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.)

By using two or more of these coupling components can get images of any color tones will. It is expedient to heat-sensitive the invention Recording material a basic substance add to accelerate the color formation. A such substance is a substance that is hardly soluble in water or is insoluble or one that occurs when heated Alkali supplies.

Examples of basic substances used in the invention are nitrogen-containing compounds, such as B. organic ammonium salts, an organic Amine, amide, urea or thiourea and its derivatives, Thiazoles, pyrroles, pyrimidines, piperazines, guanidines, indoles, Imidazoles, imidazolines, triazoles, morpholines, piperidines, Amidines, formamidines, pyridines and the like. Especially ammonium acetate, tricyclohexylamine, tribenzylamine, Octadecylbenzylamine, stearylamine, arylurea,  Thiourea, methylthiourea, arylthiourea, Ethylene thiourea, 2-benzylimidazole, 4-phenylimidazole, 2-phenyl-4-methyl-imidazole, 2-undecyl-imidazoline, 2,4,5-trifuryl imidazoline, 1,2-diphenyl-4,4-dimethyl-2-imidazoline, 2-phenyl-2-imidazoline, 1,2-ditolyl guanidine, 1,2-dicyclo- hexylguanidine, 1,2,3-tricyclohexyl guanidine, guanidine trichloroacetate, N, N′-dibenzylpiperazine, 4,4′-dithiomorpholine, Morpholinium trichloroacetate, 2-aminobenzothiazole, 2-benzoyl hydrazino-benzothiazole and the like. These basic substances can also be in the form of a combination of two or more the same can be used.

Microcapsules which can be used according to the invention, are not just those as used in common recording materials already used and by heat or pressure are destroyed, but also those that Show wall through which reactive substances inside and can penetrate outside the capsules to react with each other when heated. With regard on the color formation by heat are the latter Microcapsules preferred. The use of this Microcapsules are explained in more detail below.

Below are those which are preferably used in accordance with the invention Microcapsules described. According to the invention reactive substance that is the core substance in the Microcapsule is enclosed, dissolved or dispersed in water using an organic water-insoluble Solvent and emulsified. Then by polymerization a microcapsule wall is formed. When used organic solvents are involved in this Trap preferably around one with a boiling point of 180 ° C or higher. These include, for example, a phosphate, Phthalate, fatty acid amide, alkylated biphenyl, alkylated Terphenyl, chlorinated paraffin, alkylated naphthalene, Diarylethane and the like  

Tricresyl phosphate, diphenylcresyl phosphate, Tricyclohexyl phosphate, dibutyl phthalate, Dioctyl phthalate, dilauryl phthalate, dicyclohexyl phthalate, Butyl oleate, diethylene glycol dibenzoate, dioctyl sebacinate, Dibutyl sebacinate, dioctyl adipate, trioctyl trimellithate, Acetyl triethyl citrate, octyl maleate, dibutyl maleate, isopropyl biphenyl, Isoamylbiphenyl, chlorinated paraffin, diisopropylnaphthalene, 1,1-ditolylethane, 2,4-di-t-aminophenol, N, N-dibutyl-2-butoxy-5-t-octylaniline and the like.

Among these, the ester solvents such as. B. dibutyl phthalate, Diphenylcresyl phosphate, tricresyl phosphate, diethyl phthalate, Dibutyl maleate and the like, particularly preferred. If a wall is made from a macromolecular substance by emulsifying a Core substance that is a reactive substance, such as. B. contains a color former and the like. Oil droplets obtained is formed around, the reactant according to the invention becomes Formation of a macromolecular substance inside and / or added outside of the oil droplet. examples for suitable macromolecular substances are polycarbonate, Polyurea, polyamide, polyester, a Urea-formaldehyde resin, a melamine resin, polystyrene, a styrene / methacrylate copolymer, a styrene / acrylate copolymer, Gelatin, poly (vinyl pyrrolidone), poly (vinyl alcohol) and the like. These macromolecular substances can also be used in Form a combination of two or more of these compounds can be used according to the invention.

Among the above substances are polyurethane, polyurea, Polyamide, polyester, polycarbonate and the like. According to the invention prefers. Polyurethane is particularly preferred and polyurea.

The process of making a wall of a microcapsule by polymerizing the reactant from inside a Oil droplets out is advantageous according to the invention since it  so it is possible to capsules within a short period of time manufacture with a uniform diameter that is suitable are for the production of a recording material with an excellent durability or shelf life in fresh condition.

The method described above and the above Examples of compounds mentioned are as follows briefly described, described in U.S. Patents 37 26 804 and 37 96 669.

When using polyurethane as the material for a capsule wall will be a polyisocyanate and the second substance (for example, a polyol and a polyamine) that with the Polyisocyanate reacts to form the wall in one mixed in oily liquid to be encapsulated. The mixture is dispersed in water and emulsified and then the temperature of the resulting emulsion increases the reaction to form a macromolecule drain around the surface of the oil droplets to let. In this case it is possible to remove the oily liquid as an auxiliary solvent that has a high resolution and has a low boiling point.

The polyisocyanate used to form the capsules and the polyol and the polyamine and the like React polyisocyanate are in US Pat. No. 3,281,383, 37 73 695 and 37 93 268, in Japanese Patent Publications 4 03 473 and 2 41 594 and in Japanese OPI Patent applications 80 191/73 and 84 086/73 described. The examples given therein can also be according to the invention be used.

To accelerate the urethane formation reaction, a Catalyst such. B. a tin salt can be used.

A heat sensitive material with an excellent Shelf life or shelf life when fresh  is particularly available when the polyisocyanate as the first substance and the polyol as the second substance for the formation of the wall of the microcapsule is used.

By choosing a combination of the first substance and the second substance can be heat permeability controlled for the reactant in any way.

Examples of polyisocyanates used as the first substance Formation of a wall membrane can be used Diisocyanates, such as m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-trilene diisocyanate, 2,4-trilene diisocyanate, naphthalene 1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyldiphenylmethane 4,4'-diiosocyanate, 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 1,4-diisocyanate and the like; Triisocyanates such as 4,4 ′, 4 ″ - Triphenylmethane triisocyanate, toluene-2,4,6-triisocyanate and the like; Tetraisocyanates, such as. B. 4,4'-dimethylphenylmethane 2,2 ', 5,5'-tetraisocyanate and the like; Isocyanate prepolymers, such as B. an addition product of hexamethylene diisocyanate and trimethylolpropane; an addition product of 2,4-trilene diisocyanate and trimethylolpropane; an addition product of xylylene diisocyanate and trimethylol propane and an addition product of trilene diisocyanate and hexanetriol and the like

Examples of those that can be used to form a wall membrane second substance, d. H. for usable polyols are aliphatic and aromatic polyhydroxy alcohols, hydroxypolyesters and hydroxypolyalkylene ether. Preferred polyols are those between their two hydroxyl groups Molecular structures the group (1) given below,  (2), (3) or (4). This is for example to polyhydroxy compounds with a molecular weight of no more than 5,000.

(1) Aliphatic hydrocarbon groups having 2 to 8 carbon atoms
where Ar in (2), (3) and (4) stands for a substituted or unsubstituted aromatic radical. An aliphatic hydrocarbon group of the above radical (1) has a -C _n H _{2 n} basic structure and the hydrogen atom here can be replaced by others Elements can be substituted.

Examples of group (1) are ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, propylene glycol, 2,3-dihydroxybutane, 1,2-dihydroxybutane, 1,3-dihydroxybutane, 2,2- Dimethyl-1,3-propanediol, 2,4-pentanediol, 2,5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, di- hydroxycyclohexane, diethylene glycol, 1,2,6-trihydroxyhexane, Phenylethylene glycol, 1,1,1-trimethylolpropane, hexanetriol, Pentaerythritol, glycerin and the like

Examples of group (2) are condensation products of aromatic polyhydroxy alcohols, such as 1,4-di- (2-hydroxyethoxy) benzene, resorcinol dihydroxyethyl ether and the like. and alkylene oxide.  

Examples of group (3) are p-xylylene glycol, n-xylylene glycol, α, α′-dihydroxy-p-diisopropylbenzene and the like.

Examples of group (4) include 4,4'-dihydroxydiphenylmethane, 2- (p, p'-dihydroxy-diphenylmethyl) benzyl alcohol, an addition product of bisphenol A and ethylene oxide, an addition product of bisphenol A and propylene oxide and the like. It is desirable to use the polyol in such Amount to use that the proportion of the hydroxyl group 0.02 to 2 moles per mole of an isocyanate group is.

According to the invention, it is also possible to produce microcapsules using a water-soluble macromolecule. This macromolecule can be an anionic, non-ionic or amphoteric water-soluble macromolecule and can be natural or synthetic. Examples of such macromolecules are those having a -COO ^- or -SO ₃ ^- group and the like. Particularly advantageous examples of naturally occurring anion macromolecules are gum arabic, alginic acid and the like, and examples of a semisynthetic macromolecule are carboxymethyl cellulose, phthalated gelatin, sulphated starch, sulphated cellulose, lignin sulphonic acid and the like. including the hydrolyzed derivatives thereof), polymers and copolymers of an acrylic acid system (including those of the methacrylic acid system), polymers and modified polyvinyl alcohol and the like. Examples of amphoteric compounds are gelatin and the like.

Most among these water-soluble macromolecules preferably a polyvinyl alcohol with a degree of saponification of 75% or more and with a degree of polymerization of 300 to 2400. These macromolecules are in the form of a  0.01 to 20 wt .-% aqueous solution used.

The diameter of the microcapsules used according to the invention is set to 20 µm or less. General applies that if the diameter is more than 20 µm, the quality of imaging is deteriorating. Especially when heating with a thermal head performed on the side coated with the microcapsules , it is preferable to set the diameter to 8 µm or less to set one caused by pressure To avoid fogging.

In the manufacture of the heat-sensitive according to the invention Recording material becomes a representative of the component the heat sensitive layer, d. H. a diazo compound, a coupling component and, if necessary, a basic substance enclosed in microcapsules. Two or three representatives of the Components are encapsulated. If two representatives in Microcapsules are included, they can be in the same Microcapsule or enclosed in separate microcapsules be. In the case of microencapsulation, three representatives of the components, although not in the same microcapsule can be contained, different Combinations of the three components are available. The components, that should not be encapsulated outside the microcapsules in the heat sensitive Layer before.

The sterically hindered phenol compounds used in the invention can either be microencapsulated or they can be outside the microcapsules.

The microcapsules are made using a Emulsion containing 0.2% by weight or more of the component,  that should be included in it.

The desired proportion of the three components used according to the invention, ie the diazo compound, the coupling component and, if necessary, the basic substance, is 0.1 to 10 parts by weight of coupling component and 0.1 to 20 parts by weight of basic substance 1 part by weight of the diazo compound. This proportion does not vary, regardless of whether the component is microencapsulated or not. A diazo compound is also preferably used in an amount of 0.05 to 5.0 g / m ² .

If the color former, the developer and the basic substance are not enclosed in a microcapsule it preferred that they be used using a sand mill and Like. Together with a water-soluble macromolecule as Solid dispersed. In this case it is preferred water-soluble macromolecule one that is used to manufacture the microcapsules. His Concentration is 2 to 30% by weight and the color former, the developer and the basic substance are combined in one Amount of 4 to 40% by weight, based in each case on the macromolecule solution, used.

The particle size of the components is expediently 10 μm Or less.

To improve the thermal color-forming properties of the heat-sensitive recording material can be a hydroxy compound, a carbamic acid ester compound, an aromatic Methoxy compound or an organic sulfonamide compound be added.  

With these compounds it is possible to get the melting point the coupling component or the basic substance reduce or the thermal permeability of the microcapsule walls improve, which at the time of thermal recording the image density is increased.

Specific examples of hydroxy compounds are phenolic compounds, such as p-t-butylphenol, p-t-octylphenol, p-α- Cumylphenol, p-t-pentylphenol, m-xylenol, 2,5-dimethylphenol, 2,4,5-trimethylphenol, 3-methyl-4-isopropylphenol, p-benzylphenol, o-cyclohexyphenol, p- (diphenylmethyl) - phenol, p- (α, α-diphenylethyl) phenol), o-phenylphenol, p- Hydroxyethyl benzoate, p-hydroxybutyl benzoate, p-hydroxybenzyl benzoate, p-methoxyphenol, p-butoxyphenol, p-heptyloxyphenol, p-benzyloxyphenol, 3-hydroxydimethylphthalate, Vanillin, 1,1-bis (4-hydroxyphenyl) dodecane, 1,1-bis (4- hydroxyphenyl) -2-ethylhexane, 1,1-bis- (4-hydroxyphenyl) -2- methylpentane, 2-t-butyl-4-methoxyphenol, 2,2'-dihydroxy- 4-methoxybenzophenone and the like

Specific examples of alcoholic compounds are 2,5-dimethyl-2,5-hexanediol, resorcinol di (2-hydroxyethyl) - ether, resorcinol mono- (2-hydroxyethyl) ether, salicyl alcohol, 1,4-di- (hydroxyethoxy) benzene, p-xylene diol, 1-phenyl 1,2-ethanediol, diphenylmethanol, 1,1-diphenylethanol, 2-methyl-2-phenyl-1,3-propanediol, 2,6-dihydroxymethyl p-cresolbenzyl ether, 3- (o-methoxdyphenoxy) -1,2-propanediol and the like

Specific examples of carbamate compounds are N- Phenylethyl carbamate, N-phenyl-benzyl-carbamate, N-phenylphenethyl carbamate, Benzyl carbamate, butyl carbamate, isopropyl carbamate and the like

Examples of aromatic methoxy compounds are 2-methoxybenzoate, 3,5-dimethoxyphenylacetate, 2-methoxynaphthalene, 1,3,5-trimethoxybenzene, p-dimethoxybenzene, p-  Benzyloxymethoxybenzene and the like.

Specific examples of suitable sulfonamides are p-toluenesulfonamide, o-toluenesulfonamide, benzenesulfonamide, N- (p-methoxyphenyl) -p-toluenesulfonamide, N- (p-chlorophenyl) - p-toluenesulfonamide, N- (o-chlorophenyl) -p-toluene- sulfonamide, N- (p-tolyl) -p-toluenesulfonamide, N- (o-tolyl) - p-toluenesulfonamide, N- (o-hydroxyphenyl) -p-toluenesulfonamide, N-benzyl-p-toluenesulfonamide, N- (2-phenethyl) -p- toluenesulfonamide, N- (2-hydroxyethyl) -p-toluenesulfonamide, N- (3-methoxypropyl) -p-toluenesulfonamide, N- (p-tolyl) - sulfonamide, N- (o-tolyl) sulfonamide, N- (p-methoxyphenyl) - sulfonamide, N- (o-methoxy) sulfonamide, N- (p-chlorophenyl) - sulfonamide, N- (o-chlorophenyl) sulfonamide, N-benzylmethanesulfonamide, N- (2-phenoxyethyl) methanesulfonamide, 1,3-bis (methanesulfonylamino) benzene, 1,3-bis (p-toluenesulfonylamino) propane and the like

The above compounds can be used together with the Main components of the heat sensitive layer in microcapsules included or they can be a coating solution to manufacture the heat sensitive Recording material added outside the microcapsules will. The first of these two methods prefers. In both cases, however, the amount the compound to be added more appropriately Selected from the range of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, depending on the desired Color density.

To the yellowing of the background after fixing with Reducing light can be a polymerizable compound with an unsaturated ethylene bond (hereinafter referred to as Designated vinyl monomer) the heat-sensitive according to the invention Recording material can be incorporated.

The vinyl monomer is a compound  with at least one unsaturated ethylene bond (such as vinyl and vinylidene groups and the like) in its chemical structure and it can be in different chemical Forms, for example as a monomer or as a prepolymer, d. H. as dimeres, trimeres or other Oligomers, in the form of their mixtures and copolymers and The like. Examples of suitable vinyl monomers are an unsaturated carboxylic acid and its salt, a Esters of an unsaturated carboxylic acid and an aliphatic Polyhydroxy alcohol compound, an amide of an unsaturated Carboxylic acid and an aliphatic polyhydroxyamine compound and the like

The amount of the vinyl monomer used is 0.2 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 1 part by weight of the diazo compound. The monomer is combined with a diazo compound in Microcapsules included. In this case there can be one Part or all of the organic solvent (or a Dispersing medium) which is used for substances which by which vinyl monomers are to be encapsulated, replace. However, it is not necessary to use the vinyl monomer in such an amount to admit that these substances hardens.

When a diazo compound in the heat sensitive of the invention Recording material enclosed in microcapsules becomes a coupling reaction deactivator added outside the microcapsules so that the diazo compound, which is in the liquid phase, and the one those in imperfect capsules (i.e. the diazo compound, which are not sufficiently blocked by the microcapsule walls is) with which the deactivator reacts in order to Diazo compound its coupling reactivity (its Color formation ability), causing fogging can be prevented.  

Any coupling reaction deactivator can be used Substance can be used, which is the coloring or color formation of the solution in which a diazo compound has been dissolved. It can be selected by dissolving a diazo compound in water or in a organic solvent, adding another compound, dissolved in water or in an organic solvent, to the resulting solution and viewing the color change of the diazo compound.

Examples of suitable substances of this type are hydroquinone, Sodium bisulfite, potassium nitrite, hypophosphorous Acid, tin (II) chloride, formalin and the like. In addition, they are selected from those described in "The Aromatic Diazo Compounds and their Technical Applications " by K.H. Sawnders, M.C., M.A. (Cant ab.) B. Sc. (London), 1949, pages 105-306.

Preferred coupling reaction deactivators are those which are themselves not very colored, especially in water are soluble and result in fewer side reactions. they are used in an amount such that the thermal color formation reaction a diazo compound is not inhibited becomes. The preferred amount is usually 0.01 to 2 moles, in particular 0.02 to 1 mole, per mole of those used Diazo compound.

The coupling reaction deactivator used according to the invention is dissolved in a solvent and added to a solution in the microcapsules that is a diazo compound contained, have been dispersed into a solution, in which a coupler or a basic substance is dispersed or a mixture of the two Solutions. It is particularly preferred to use the deactivator to use in the form of its aqueous solution.

To prevent the heat sensitive from sticking  Recording material on a thermal head and for This can improve its playback properties heat-sensitive recording material according to the invention Pigments such as B. silicon dioxide, barium sulfate, Titanium oxide, aluminum hydroxide, zinc oxide, calcium carbonate and the like, or fine powder of styrene beads, urea Melamine resin and the like can be added.

Sticking can also be prevented by adding metal soaps. The amounts in which they are to be used are 0.2 to 7 g / m ² .

According to the invention, a heat-melting substance can be added to the heat-sensitive recording material in order to increase the thermal recording density. Such a heat-melting substance is a solid at normal temperature, which melts when heated with a heat head at 50 to 150 ° C. It can melt the diazo compound, the coupling component or the basic substance and it is usually used in an amount of 0.2 to 7 g / m ² in the form of a solid material, whereby it is in the form of particles with a size of 0.1 is dispersed up to 10 microns. Examples of such a heat-melting substance are a fatty acid amide, an N-substituted fatty acid amide, ketone compounds, urea compounds, esters and the like.

The heat-sensitive material according to the invention can be produced in the form of a layer using a suitable binder. Various emulsions of polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, gum arabic, gelatin, polyvinyl pyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic acid ester, ethylene / vinyl acetate copolymer and the like are used as binders. The amount in which it is used is 0.5 to 5 g / m ² as a solid material.

In addition, according to the invention, citric acid, Tartaric acid, oxalic acid, boric acid, phosphoric acid, Pyrophosphoric acid and the like are added.

The heat-sensitive recording material according to the invention is produced by preparing a coating solution, which main components, such as. B. a color former, a developer and the like., And contains other additives, by coating a support, for example of paper, synthetic resin films and the like., With the resulting solution using the rod coating, the blade coating, the air knife coating, the gravure coating, the roller coating , spray coating, dip coating and the like., and drying to form a heat-sensitive layer containing a solid material in an amount of 2.5 to 25 g / m ² . Another method makes it possible to manufacture a multi-layer type: the main components, such as. For example, a developer, a color-forming reaction aid or other additives are added as core substances to a microcapsule or dispersed as a solid, or they are dissolved to prepare an aqueous solution and then mixed to prepare a coating solution. The solution obtained is applied in the form of a layer on a support and dried to form a preliminary coating layer which contains a solid material in an amount of 2 to 10 g / m ² . In addition, a main component, such as. B. a color former and other additives, added as core substances to a microcapsule solution and then mixed to prepare a coating solution which is applied over the above-described pre-coat layer, and dried to prepare a coat layer containing a solid material in an amount of 1 to 15 g / m ² contains. The heat-sensitive recording material of this multilayer type can have a multilayer coating which has been produced by reversing the above-mentioned process measures. In any case, the layers can be applied sequentially or simultaneously. Such a heat-sensitive recording material of the multilayer type is advantageous because it has a particularly good long-term storage stability or shelf life in the fresh state.

The heat sensitive layer can also be on an intermediate layer be applied on a support has been applied as in the Japanese patent application 1 77 669/84.

The invention is illustrated by the following examples explained, but is not limited to this. The Unit of measure "parts" given therein refers to the weight (parts by weight).

example 1

100 g of compound A became 200 g of a 5% aqueous solution Solution of polyvinyl alcohol (PVA 205, trade name for a product from Kurare Co., Ltd.) added and dispersed using a ball mill for 24 hours for the preparation of solution A. 18 g of compound (B-1), 2 g of compound (B-2), 20 g of compound C and 60 g Compound (D-1) became 200 g of a 5% aqueous solution Solution of polyvinyl alcohol added and using a ball mill dispersed for 24 hours for manufacture the solution (B-D).

Then 400 g calcium carbonate was added to 600 g water and dispersed using a dissolver for the preparation of a pigment solution.

In addition, 30 g of the compound (E-1) became 170 g of one 5% aqueous solution of polyvinyl alcohol added and dispersed using a ball mill for one  24-hour period for the preparation of a solution E.

2 parts of the solution A, 10 parts of the solution (BD), 5 parts of the pigment solution and 3 parts of the solution E were mixed together to prepare a coating solution which was applied to a high quality paper by rod coating to obtain a coating amount of 8 g / m ² , based on the dry weight. The resulting paper was dried at room temperature to obtain a heat sensitive recording material (1).

Test procedure

Thermal recording was done using the as the heat-sensitive recording material prepared above in a GIII mode thermal printer (UF-2, manufactured by Matsushita Denso Co., Ltd.) carried out. The material provided with the recording was used for fixation using a Recopy Superdry 100 device (manufactured by Ricoh Co., Ltd.) fully exposed. The density of what is obtained recorded image was recorded using a McBeth Reflection densitometer measured. In addition, the Yellow density of the image background measured. The results are given in Table I below. Although also another heat record on the as indicated above fixed part was attempted, no picture recorded, thereby confirming that the fixation had taken place in a suitable manner.

Then the shelf life or durability examined in the raw state. The density (obfuscation) the background of a heat sensitive recording material and disguising the same Materials after a forced breakdown test, in which the Material in a dark place at a temperature of  40 ° C and a relative humidity of 90% (RH) Had been kept for 24 hours of a McBeth reflection densitometer to measure the Determine change in fog density. For testing the stability of the color image and the yellowing of the Image background after fixing it was after Fix obtained recorded image irradiated for 24 h using a xenon fadeometer (FAL-25 AX-HC type manufactured by Suga Shikenki Co., Ltd.) and the densities of the resulting recorded The image and the background of the image were measured. The results are shown in Table I.

The compounds used to prepare the samples were the following:

Compound A: diazonium salt Compound B-1: coupler Compound B-2: coupler Compound C: organic basic compound Compound D-1: color enhancer Compound E-1: hindered phenol compound

Table I

Comparative Example 1

A comparative sample (Comparative-1) was made on the same Prepared as indicated in Example 1, wherein this time no solution E was used. It became the same test as in Example 1 carried out. The results are given in Table I.

From Table I it appears that the invention heat-sensitive recording material in four points is improved, d. H. in terms of background density at the time of recording, in terms of image deterioration after the record, with respect to the Yellowing of the background after recording and with regard to the shelf life in the raw state before the Recording.

Examples 2 to 4

In the same manner as described in Example 1 heat-sensitive recording materials (2), (3) and (4), this time the compounds (E-2), (E-3) and (E-4) instead of the compound (E-1) for the Solution E were used. It was the same test as carried out in Example 1, the results of which in Table I are given. The connections (E-2), (E-3) and (E-4) are given below.  

Compound E-2: hindered phenol compound Compound E-3: hindered phenol compound Compound E-4: hindered phenol compound Example 5

In the same way as described in Example 1 a heat-sensitive recording material (5) prepared, but this time 30 g of the compound (III-29), which is an example of an invention color image stabilizer used, used instead of compound (E-1) for solution E. has been.

The same test as in Example 1 was carried out. The results are shown in Table II below.

Examples 6 to 8

Following the same procedure as in Example 5 heat-sensitive recording materials (6), (7) and (8), this time instead of that for the solution E compound (III-29) used the compounds (III-2), (III-12) and (III-18) were used. It the same test as in Example 1 was carried out, the results of which are given in Table II.

Compounds (III-2), (III-12) and (III-18) are compounds that are used as examples in the description are given.

Comparative Example 2

In the same way as in Example 5, a comparative sample was made (Comparison-2) made this time no solution E was used. It was the same test as in Example 1. The results are in given in Table II.

As can be seen from the results of Table II,  has been shown that the heat sensitive invention Recording material improved in four points is, d. H. with respect to the density of the background to Date of recording, in relation to the deterioration of the picture after recording, in relation to the Yellowing of the background after recording and in relation to the shelf life in the raw state the record.  

Table II

Example 9

In the same manner as in Example 1, a heat sensitive one Recording material (9) produced, wherein this time 30 g of compound (IV-1), which is an example of a given in the description Color image stabilizer acts instead of that for the solution E compound used (E-1) was used.

The same test as in Example 1 was carried out. The results are shown in Table III.

Example 10

In the same manner as in Example 9, a heat sensitive one Recording material (10) produced, wherein this time the compound (IV-3), which is one in the description given example of a color image stabilizer represents, instead of those used for the solution E. Compound (IV-1) was used.

The same test as in Example 1 was carried out. The results are shown in Table III.

Comparative Example 3

A comparative sample (Comparative-3) was made on the prepared in the same way as in Example 9, this time no solution E was used. It was the same Test carried out as in Example 1. The results are given in Table III.  

Table III

Example 11

In the same manner as in Example 1, a heat sensitive one Receiving recording material (11), wherein but this time 30 g of the compound (V-1) in which it is an example given in the description for a color image stabilizer instead of compound (E-1) used for solution E. has been.

The same test as in Example 1 was carried out. The results are shown in Table IV below.

Example 12

In the same manner as in Example 11, a heat sensitive one Recording material (12) produced, this time the connection (V-3), which is an example of a color image stabilizer mentioned in the description acts instead of those used for solution E. Compound (V-1) was used.

The same test as in Example 1 was carried out. The results are shown in Table IV.

Comparative Example 4

A comparative sample was made in the same manner as in Example 11 (Comparison-4), this time no solution E was used. It was the same test as in Example 1. The results are in given in Table IV.  

Table IV

Example 13

The following is an example of a microencapsulation compound A described.

150 g of methylene chloride were added to 50 g of compound A, 50 g tricresyl phosphate, 150 g trimethylolpropane trimethacrylate, 200 g of a 75% ethyl acetate solution Addition product of m-xylene diisocyanate and trimethylolpropane (3: 1) (TAKENET DIION: trade name for a product from Takeda Yakuhin Kogyo Co., Ltd.) and evenly mixed with it to produce an oil phase Solution.

On the other hand, 600 g of 7% polyvinyl alcohol (PVA 217E, degree of saponification 88 to 89%, degree of polymerization 1700, trade name for a product of KURARE Co., Ltd.) in an aqueous solution of a water-soluble macromolecular Connection transferred.

An aqueous solution of the protective colloid was poured into a 5 liter Stainless steel container with a heating bath and was equipped with a dissolver. Then the oil phase solution became the dissolver with stirring admitted. The emulsification / dispersion was continued until the average particle size was about 1.5 µm. As the dispersion completely was stirring was stopped while warm water from 42 ° C introduced into the heating bath (internal temperature 40 ° C) to perform an encapsulation reaction for 3 hours. The obtained solution (A-1) was as follows specified used after with an ion exchange resin the diazonium salt that had not been encapsulated had been removed.

A coating solution was prepared by mixing 5 parts of the solution (A-1) and 7 parts of the solution (BD), 3.5 parts of a pigment solution, 2.1 parts of the solution E as used in Example 1. then a high quality paper was coated with it in a coating amount of 10 g / m ² based on the dry weight. In this way, the heat-sensitive recording material (13) was obtained.

The same test as in Example 1 was carried out. The results are shown in Table V below.

Examples 14 to 16

In the same manner as in Example 13, heat-sensitive ones became Recording materials (14), (15) and (16), this time the one in Examples 2 to 4 solutions E used instead of those in Example 13 used Solution E were used.

The same test as in Example 1 was carried out. The results are shown in Table V.

Example 17

The following is an example of a microencapsulation compound A and a compound (E-1) described.

A solution (A-2) was made in the same manner as in Example 13 obtained, but this time 5 g of the compound (E-1) were added to the oil phase solution to make a Perform microencapsulation reaction.

A heat-sensitive recording material ( 17 ) was obtained in the same manner as in Example 13, except that solution (A-2) was used instead of solution (A-1).

The same test as in Example 1 was carried out.  

The results are shown in Table V.

Examples 18 to 20

In the same manner as in Example 17, heat-sensitive ones became Recording materials (18), (19) and (20) prepared, this time the compounds (E-2), (E-3) and (E-4) instead of the compound used for solution E. (E-1) were used. It was the same test as carried out in Example 1, the in Table V specified results were obtained.

Comparative Example 5

A comparative sample was made in the same manner as in Example 13 (Comparison-5), but none Solution E was used. It was the same test as in Example 1 performed. The results are in the table V. specified. The results of Table V show that that the effect of sterically hindered phenols readily is evident and through these results the Usability of the present invention confirmed.  

Table V

Example 21

A coating solution was prepared by mixing 5 parts of the solution (A-1) prepared in Example 13 and 7 parts of the solution (BD), 3.5 parts of a pigment solution, 2.1 parts of the solution E described in Example 5 was used, then a high quality paper was coated in a coating amount of 10 g / m ² based on the dry weight. There was thus obtained the heat-sensitive recording material (21) in which Compound A was microencapsulated in exactly the same manner as in Example 13.

The same test as in Example 1 was carried out. The results are in the table below VI specified.

Examples 22-24

In the same manner as in Example 21, heat-sensitive ones became Recording materials (22), (23) and (24) prepared, this time that in Examples 6 to 8 Solutions E used instead of those in Example 21 Solution E used were used.

The same test as in Example 1 was carried out, the results of which are given in Table VI.

Example 25

In the same manner as in Example 13, a solution was obtained (A-3), this time 5 g of compound (III-29), those in the description as an example of a color image stabilizer is indicated, the oil phase solution were added to carry out a microencapsulation reaction.

In the same manner as in Example 21, a heat sensitive one  Recording material (25) produced, this time the solution (A-3) instead of the solution (A-1) has been used.

The same test as in Example 1 was carried out. The results are shown in Table VI.

Examples 26 to 28

In the same manner as in Example 25, heat-sensitive ones became Recording materials (26), (27) and (28) prepared, this time instead of compound (III-29) the compounds (III-2), (III-12) and (III-18) are used were. The same test as in Example 1 was carried out, where the results given in Table VI were obtained. For the compounds (III-2), (III-12) and (III-18) are compounds as described in the Description are given as examples.

Comparative Example 6

A comparative sample was made in the same manner as in Example 21 (Comparison-6), but this time no solution E was used.

The same test as in Example 1 was carried out. The results are given in Table VI, which show that a color image stabilizer is still effective is when a diazo compound has been microencapsulated. The effectiveness of the compound of the formula (III) proven.  

Table VI

Example 29

A coating solution was prepared by mixing 5 parts of the solution (A-1) prepared in Example 13 and 7 parts of the solution (BD), 3.5 parts of the pigment solution, 2.1 parts of the solution E used in Example 9 then it was applied to a high quality paper in a coating amount of 10 g / m ² based on the dry weight. There was thus obtained a heat-sensitive recording material (29) in which Compound A was encapsulated in exactly the same manner as in Example 13.

The same test as in Example 1 was carried out. The results are shown in Table VII below.

Example 30

In the same manner as in Example 29, a heat sensitive one Receiving recording material (30), wherein this time the solution used in Example 10 instead of the solution used in Example 29 was used. It the same test as in Example 1 was carried out. The results are shown in Table VII.

Example 31

In the same manner as in Example 13, a solution was obtained (A-4) obtained, this time 5 g of compound (IV-1), which is a specified in the description Example of a color image stabilizer, the oil phase Solution were added to a microencapsulation reaction perform.

In the same manner as in Example 29, a heat sensitive one was obtained Recording material (31) obtained), wherein this time using solution (A-4) instead of solution (A-1)  has been.

The same test as in Example 1 was carried out. The results are shown in Table VII.

Example 32

In the same manner as in Example 31, a heat sensitive one Received recording material (32), wherein this time the compound (IV-3), which is an in Example of a color image stabilizer given in the description is used instead of the compound (IV-1) has been.

The same test as in Example 1 was carried out. The results are shown in Table VII.

Comparative Example 7

A comparative sample was made in the same manner as in Example 29 (Comparison-7), but this time no solution was used.

The same test as in Example 1 was carried out. The results are shown in Table VII.

From Table VII it appears that the invention heat-sensitive recording material in four points is improved, d. H. in terms of the density of the background at the time of recording, with respect to the Image deterioration after recording, in relation on the yellowing of the background after the recording and in terms of shelf life in the raw state before recording. These effects are preserved even when a diazo compound is microencapsulated. This example shows the effectiveness of the connection of formula (IV) demonstrated.  

Table VII

Example 33

A coating solution was prepared by mixing 5 parts of the solution prepared in Example 13 and 7 parts of the solution (BD), 3.5 parts of the pigment solution, 2.1 parts of the solution E used in Example 11, and then on a paper with a high quality in a coating amount of 10 g / m ² , based on the dry weight, applied in the form of a layer. There was thus obtained the heat-sensitive recording material (33) in which Compound A was encapsulated in exactly the same manner as in Example 13.

The same test as in Example 1 was carried out. The results are shown in Table VIII below.

Example 34

In the same manner as in Example 33, a heat sensitive one Receiving recording material (34), wherein this time the solution E used in Example 12 instead of Solution E used in Example 33 was used.

The same test as in Example 1 was carried out. The results are shown in Table VIII.

Example 35

A solution (A-5) was made in the same manner as in Example 13 obtained, this time 5 g of compound (V-1), which is one in the description as an example specified color image stabilizer, the oil phase Solution were added to a microencapsulation reaction perform.

One was obtained in the same manner as in Example 33  heat-sensitive recording material (35), this time a solution (A-5) is used instead of the solution (A-1) has been.

The same test as in Example 1 was carried out. The results are shown in Table VIII.

Example 36

In the same manner as in Example 35, a heat sensitive one Receiving recording material (36), wherein this time the connection (V-3), which is an in Example of a color image stabilizer given in the description is used instead of the compound (V-1) has been.

The same test as in Example 1 was carried out. The results are shown in Table VIII.

Comparative Example 8

A comparison sample (comparison-8) was made on the same Made as in Example 33, but this time none Solution E was used.

The same test as in Example 1 was carried out. The results are shown in Table VIII.

Table VIII shows that the invention heat-sensitive recording material in four points is improved, namely in terms of the density of the background at the time of recording, with respect to the Image deterioration after recording, in relation on the yellowing of the background after the recording and in terms of shelf life in the raw state before recording. The effect is preserved even when a diazo compound is microencapsulated. By  these examples will demonstrate the effectiveness of compound V proven.  

Table VIII

Example 37

In the same manner as in Example 1, a solution (BD) 'was prepared, except that a compound (D-2) was used instead of the compound (D-1) as an agent for improving the heat-coloring properties. Then, a coating solution was prepared in the same manner as in Example 5 using 5 parts of the solution (A-1), 7 parts of the solution (BD) ', 3.5 parts of a pigment solution and 2.1 parts of the Solution E of the compound (E-1), then was applied in the form of a layer on a high quality paper in a coating amount of 10 g / m ² based on the dry weight. In this way, a heat-sensitive recording material (37) was obtained.

The same test as in Example 1 was carried out. The results are shown in Table IX.

Connection (D-2) Examples 38 to 40

In the same manner as in Example 37, heat-sensitive ones became Recording materials (38), (39) and (40) prepared, this time that in Examples 2 to 4 Solution E used in each case instead of that in Example 37 Solution E used was used. It was the same Test performed as in Example 1, using the following Results given in Table IX were obtained.  

Comparative Example 9

A comparative sample was made in the same manner as in Example 37 (Comparison-9), but this time none Solution E was used.

The same test as in Example 1 was carried out.

As can be seen from the results in Table IX the heat-sensitive recording material according to the invention excellent properties. The effectiveness the invention is the same even if different Color enhancer is used, which shows that the Effect of the present invention in particular by the Addition of a sterically hindered phenol is achieved.  

Table IX

Examples 41 to 45

Below is an example of examining the influence varying amounts of a sterically hindered phenol compound described when using the compound (E-2), when the compound (A) is microencapsulated.

As in Example 13, a coating solution was prepared by adding the solution E (containing the compound (E-2)) in an amount of 0.085, 0.34, 1.7, 5.1 and 10.2 parts to mixtures which each contained 5 parts of the solution (A-1), 7 parts of the solution (BD) and 3.5 parts of a pigment solution. The resulting solution was applied in the form of a layer to a high quality paper in a coating amount of 10 g / m ² , in each case based on the dry layer thickness. In this way, heat-sensitive recording materials (41), (42), (43), (44) and (45) were obtained.

The same test as in Example 1 was carried out. The results are shown in Table X.

Comparative Example 10

A comparative sample was made in the same manner as in Example 41 (Comparison-10), this time no solution E was used.

The same test as in Example 1 was carried out. The results are shown in Table X.  

Table X

While the invention has been described above with reference to specific preferred embodiments explained in more detail, however, it is understood by those skilled in the art that it is by no means limited to this, but that changed and modified in many ways can, without thereby the framework of the present Invention is left.

Claims (17)

1. Heat-sensitive recording material with a heat-sensitive layer applied to a support, which contains at least one diazonium salt and / or a coupler, characterized in that the heat-sensitive layer contains at least one sterically hindered phenol compound and / or a derivative thereof. 2. A heat-sensitive recording material according to claim 1, characterized in that it is steric hindered phenols around o-tert-butylphenol or derivatives is about it. 3. Heat-sensitive recording material according to claim 1 and / or 2, characterized in that the o-tert-butylphenol derivatives are those of the general formula: wherein R ₁ , R ₂ and R ₃ , which may be the same or different, each represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom. 4. Heat-sensitive recording material according to claim 1 and / or 2, characterized in that the o-tert-butylphenol derivatives are those of the general formula: in which mean:
R ₁ and R ₂ , which may be the same or different, each represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group or a halogen atom and an alkyl group or an arylene group, it being possible for the latter two groups to have further substituents. 5. Heat-sensitive recording material according to claim 1, characterized in that the sterically hindered phenol derivatives are those of the general formula: in which mean:
R and R ', which may be the same or different, each have a hydrogen atom or an alkyl group and
R ₃₁ , R ₃₂ , R ₃₃ and R ₃₄ , which may be the same or different, each represent a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an alkylthio group, an acylamino group, a hydroxyl group or a halogen atom. 6. Heat-sensitive recording material according to claim 5, characterized in that the sterically hindered phenol derivatives are those of the general formula: wherein R, R ', R ₃₁ , R ₃₂ , R ₃₃ and R _{34 have} the meanings given in claim 5. 7. Heat-sensitive recording material according to claim 5, characterized in that the sterically hindered phenol derivatives are those of the general formula: wherein R, R ₃₁ , R ₃₃ and R _{34 have} the meanings given in claim 5 and R ₃₅ to R ₄₀ , which may be the same or different, each have a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, a heterocyclic group, represent an alkylamino group or an alkoxycarbonyl group. 8. Heat-sensitive recording material according to claim 5, characterized in that the sterically hindered phenol derivatives are those of the general formula: wherein R, R ', R ₃₁ , R ₃₃ and R _{34 have} the meanings given in claim 5. 9. Heat-sensitive recording material according to claim 5, characterized in that the sterically hindered phenol derivatives are those of the general formula: wherein R, R ', R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ , R ₃₅ and R _{36 have} the meanings given in claims 5 and 7. 10. Heat-sensitive recording material according to claim 5, characterized in that the sterically hindered phenol derivatives are those of the general formula: wherein R, R ', R ₃₁ , R ₃₂ , R ₃₃ , R ₃₄ , R ₃₅ , R ₃₆ , R ₃₇ and R _{38 have} the meanings given in claims 5 and 7. 11. Heat-sensitive recording material according to claim 1, characterized in that the sterically hindered phenol derivatives are those of the general formula: in which mean:
R ₄₁ and R ₄₅ each represent a hydrogen atom, an alkyl group or a heterocyclic group with the proviso that both cannot simultaneously be hydrogen atoms, and
R ₄₂ , R ₄₃ and R ₄₄ , which may be the same or different, each represents a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an acylamino group, a diazylamino group, a sulfonamido group, an alkylamino group , an alkoxycarbonyl group, an acyloxy group or a halogen atom. 12. Heat-sensitive recording material according to claim 11, characterized in that the sterically hindered phenol derivatives are those of the general formula: wherein R ₄₆ and R ₄₇ each represent a hydrogen atom or an alkyl group, with the proviso that R ₄₆ and R ₄₇ cannot both be hydrogen atoms at the same time. 13. Heat-sensitive recording material according to claim 1, characterized in that the sterically hindered phenol derivatives are those of the general formula: in which mean:
R is a substituted or unsubstituted 4-piperidino group,
R _{53 is} a hydrogen atom or a substituted or unsubstituted alkyl group which can be the same or different on each benzene ring,
Y is a hydrogen atom or a substituted or unsubstituted alkyl group,
m is the number 1 or 2 and
m + p the number 2. 14. Heat-sensitive recording material according to claim 13, characterized in that in the general formula (V) R denotes a group of the formula in which mean:
R _{51 represents} a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group or a substituted or unsubstituted acyl group and
R _{52 is} one or more unsubstituted or substituted alkyl groups which may be the same or different and may be substituted by a hydrogen atom or a piperidino ring. 15. Heat-sensitive recording material according to claim 13, characterized in that the sterically hindered phenol derivatives are those of the general formula: wherein Y, m and p have the meanings given in claim 13 and R ₅₁ denotes a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group or a substituted or unsubstituted acyl group. 16. Heat sensitive recording material after one of claims 1 to 15, characterized in that at least a diazonium salt and / or a coupler in the  heat-sensitive layer is contained in microcapsules (are). 17. The heat-sensitive recording material according to claim 16, characterized in that the diazonium salt is contained in microcapsules.