JPH043756B2 - - Google Patents

Description

[Detailed description of the invention]

(A) Technical Field of the Invention The present invention relates to a fixable heat-sensitive recording material that develops color with high density during heat-sensitive recording and has excellent storage stability. (B) Prior art and its problems In recent years, high-speed printers, facsimile machines, etc. have made remarkable progress in response to society's demand for outputting large amounts of information as hard copies as quickly as possible. Electrophotography, electrostatic recording, discharge recording, inkjet recording, thermosensitive recording, and the like are known as methods for forming images on recording media according to electrical information, such as high-speed printers and facsimiles. Among these methods, the thermal recording method has been rapidly becoming popular in recent years because the apparatus is relatively simple and the recording paper is also relatively inexpensive. As one method of the heat-sensitive recording method, a heat-sensitive recording sheet made by combining a color-forming substance such as crystal violet lactone and a phenolic compound such as bisphenol A is described in, for example, Japanese Patent Publication No. 14039/1983. It is already known. These thermosensitive recording sheets are currently widely used as office copy paper, recording paper for various recorders, electrocardiographs, calculators, computer terminals, facsimiles, and the like. However, with the above conventional method, if the background is heated incorrectly after printing, the background may become colored and the print may become unreadable, or there is a possibility that it may be tampered with after printing.
Improvements are strongly desired. The present inventors conducted research with the intention of providing a fixable heat-sensitive recording medium that solved this problem, and first developed a guanidine derivative having a specific general formula as a basic substance that promotes the reaction between a diazonium salt and a coupler compound. We have already proposed that by using the method, it is possible to provide a fixable heat-sensitive recording medium with high sensitivity and excellent storage stability (Japanese Patent Application Laid-Open No. 57-45094,
Publication No. 57-125091). However, in recent years, there has been an increasing demand for higher color development sensitivity in thermal recording methods. This is widely recognized in type thermosensitive recording materials, and there has been a demand for fixing type thermosensitive recording materials that develop color with high density and have excellent storage stability. (C) Object of the Invention The object of the present invention is to provide a fixable heat-sensitive recording material that develops color with high density during heat-sensitive recording and has excellent storage stability. (D) Structure and operation of the invention That is, the fixable heat-sensitive recording material of the present invention contains a diazonium salt, a coupler compound, a coloring aid, and an organic base as a coloring agent and an organic base that exhibits a basic atmosphere when melted by heat as a coloring agent on a support. In a fixing heat-sensitive recording material in which a fine-particle dispersion of a sexual compound is provided in the same layer or as a light- and heat-sensitive layer consisting of two or more separate layers, a compound represented by the following general formula () is used as a coloring aid. It is characterized by General formula () (In the formula, R represents an alkyl group or an aralkyl group, and n represents an integer of 1 to 3.) The compound used in the present invention is a solid substance at room temperature with a melting point of 40 to 160°C, preferably 70 to 135°C, and It is preferable to use a material that is sparingly soluble or insoluble in water, and that can well dissolve the diazonium salt, coupler compound, and organic basic compound used as a color developer during hot melting. Specific examples of compounds used in the present invention are shown in Table 1, but the present invention is not limited thereto. Table-1 Ethylene glycol bis(P-benzyloxycarbonylphenyl) ether diethylene glycol bis(P-benzyloxycarbonylphenyl) ether ethylene glycol bis(P-isopropoxycarbonylphenyl) ether ethylene glycol bis(P-(P- chlorobenzyl)oxycarbonylphenyl) ether ethylene glycol bis(P-n-butoxycarbonylphenyl) ether ethylene glycol bis(P-(P-methylbenzyl)oxycarbonylphenyl) ether The above-mentioned substances used as coloring aids in the present invention The compound is
All of them are thermofusible and poorly soluble or insoluble in water, and are used in the form of fine particles with a particle size of 0.1 to 10 μm.
The ratio of the diazonium salt, the coupler compound, and the color development aid of the present invention is preferably in the range of 1:(0.1-10):(0.1-20) (by weight). In addition, the coloring aid is used alone,
Alternatively, two or more types can be used in combination if necessary. The effect of improving the color development sensitivity of a fixable heat-sensitive recording material by the color development aid of the present invention is observed not only when a hydrophobic guanidine derivative is used but also when a widely known organic basic compound is used as a color developer, but it is particularly preferable. Examples of organic basic compounds include the following guanidine derivatives. General formula () General formula () (In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are hydrogen, alkyl having 18 or less carbon atoms, cyclic alkyl, aryl,
Represents aralkyl, amino, alkylamino, acylamino, carbamoylamino, heterocyclic residue,
R ₆ is lower alkylene, phenylene, naphthylene,
or

[Formula] (in the formula, X represents lower alkylene, SO ₂ , S ₂ , S, O, -NH- or a single bond), and the aryl group in the formula is lower alkyl, alkoxy, nitro, acylamino, alkylamino Also included are those having substituents selected from groups and halogens. ) As the diazonium salt used in the present invention, any compound used in conventionally known diazo type copying materials can be used. For example, compounds represented by the following general formulas (), (), () can be used. It can be used particularly preferably. In the formula, R ₇ and R ₈ are alkyl having 1 to 5 carbon atoms,
or alkoxyl, oxyalkyl, benzyl, substituted benzyl, benzoyl, substituted benzoyl, phenyl group, hydrogen atom, etc., and Y and Z
represents a halogen atom, alkyl having 1 to 5 carbon atoms, carboxyl, alkoxyl having 1 to 5 carbon atoms, nitro, acetoxy group, etc., and m and n represent 0 or a positive integer of 4 or less. Also, X is Cl ^- , Br ^- ,
It represents anions such as SO ₄ ^- , NO ₃ ^- , PF ₆ ^- , ClO ₄ ^- , BF ₄ ^-, etc., as well as ions added to these anions, such as ZnCl ₂ , CaCl ₂ , or SnCl ₄ . Specific examples include 4-N,N-dimethylaminobenzenediazonium chloride, 3-chloro-4-
N,N-dimethylaminobenzenediazonium chloride, 4-N,N-diethylaminobenzenediazonium chloride, 2,5-diethoxy-4-
N,N-diethylaminobenzenediazonium chloride, 4-N-ethyl-N-hydroxyethylaminobenzenediazonium chloride, 4-N,
Examples include N-diethoxyaminobenzenediazonium chloride, 4-phenylaminobenzenediazonium chloride, and 4-N-(P-methoxyphenyl)-aminobenzenediazonium chloride. In the formula, R ₉ is −CH ₂ CH ₂ OCH ₂ CH ₂ − or −
CH ₂ OCH ₂ CH ₂ −, −CH ₂ CH ₂ CH ₂ CH ₂ −, etc. X, Y, Z, m and n have the same meanings as in the general formula (). Specific compound examples include 4-morpholinobenzenediazonium chloride, 2,5-diethoxy-4-morpholinobenzenediazonium chloride, 4-oxazolidinobenzenediazonium chloride, and 3-methyl-4-piperidinobenzene. Examples include diazonium chloride. In the formula, R ₁₀ represents an alkyl group or an aryl group.
Further, X, Y, Z, m and n have the same meanings as in the general formula (). Specific compound examples include 4-ethylmercapto-2,5-diethoxybenzenediazonium chloride, 4-tolylmercapto-2,5-diethoxybenzenediazonium chloride, and 4-benzylmercapto-2,5-dimethoxybenzenediazonium chloride. and so on. These diazonium salts can be dissolved in water or an organic solvent, or dispersed in the form of fine particles in a suitable solvent, and coated onto a support preferably in a range of 0.1 to 1.0 g/m ² . In addition, an acid compound can be used in the photosensitive and heat-sensitive layer to stabilize the diazonium salt and prevent precoupling, but this is possible by using any organic or inorganic acid compound used in conventionally known diazo type copying materials. Specific examples include tartaric acid,
Citric acid, boric acid, lactic acid, gluconic acid, phosphoric acid,
Trichloroacetic acid, dichloroacetic acid, cyanoacetic acid, oxalic acid, malonic acid, maleic acid, etc. are all preferably used. These acid compounds are preferably used in a weight ratio of 5.0 to 100%, more preferably 10 to 50%, based on the organic basic compound. Further, as the coupler compound which reacts with the diazonium salt to form an azo dye, any compound capable of coupling with the above-mentioned diazonium salt can be used. Examples of these coupler compounds include phenol derivatives, oxynaphthalene derivatives, compounds containing active methylene groups, heterocyclic compounds, and specific examples of these compounds include the following compounds. Phenol derivatives Pyrocatechol resorcin Phloroglycine Pyrogallol Meta-aminophenol Para-aminophenol Diethylaminophenol N-Lauryl-para-aminophenol N-Acyl-meta-aminophenol 3,3',5-Trihydroxydiphenyl 3,3',5,5'- Tetrahydroxydiphenyl α-resorcinic acid β-resorcinic acid γ-resorcinic acid Phloroglucinic acid Gallic acid Oxynaphthalene derivative 2,3-dihydroxynaphthalene β-naphthol α-naphthol 1,6-dihydroxynaphthalene 2,3-dihydroxy Naphthalene-6-sulfonic acid 2-naphthol-3,6-disulfonic acid 1,8-dihydroxynaphthalene-8-sulfonic acid 2-hydroxy-3-naphthoic acid-N-β-hydroxyethyl-amide 2-hydroxy-3- Naphthoic acid-N,N-bis-β-hydroxyethylamide 5-(paranitro)-benzamide-1-naphthol 1-naphthol-3-(N-β-hydroxyethyl)-sulfone-amide 2-hydroxy-3-propyl Morpholinonaphthoic acid 2-hydroxy-3-naphthoic acid-0-toluidide 2-hydroxy-3-naphthoic acid morpholinopropylamide 2-hydroxy-3-naphthoic acid-4'-chloroanilide 2-hydroxy-3-naphthoic acid-5'-chloro-2',4'-di-methoxyanilide 2-hydroxy-3-naphthoic acid-2',5'-dimethoxyanilide 2-hydroxy-3-naphthoic acid-2'-ethoxyanilide 2-hydroxy-3- Naphthoic acid-2'-methoxyanilide 2-hydroxy-3-naphthoic acid-phenyl ester 2-hydroxy-3-naphthoic acid-4'-phenoxyanilide 2-hydroxy-3-naphthoic acid-4'-benzyloxy Anilide 2-hydroxy-3-naphthoic acid-4'-phenethyloxyanilide 2-hydroxy-3-naphthoic acid-2'-benzyloxyanilide Compound containing an active methylene group 1-phenyl-3-methyl-pyrazone ( 5) Acetoacetyl acid anilide 1-phenyl-3-carboxypyrazolone acetacetyl cyclohexylamide acetyl amide benzylamide cyanoacetanilide cyanoacetomorpholin 4-carboxy-acetoacetanilide heterocyclic compound 1-(3) '-sulfoamide)-phenyl-3-methyl-pyrazolone-5 1-(4'-carboxyethyl phenyl)-3-
Dodecyl-pyrazolone-5 These coupler compounds are dissolved in water or an organic solvent, or incorporated into the light and heat sensitive layer as a fine particle dispersion with a particle size of 10 μm or less using a dispersion means such as a ball mill or a sand grinder attritor. I can do it. Further, two or more coupler compounds may be combined, if necessary, to produce a combination of dyes exhibiting desired spectral absorption characteristics. Further, during dispersion, the coupler compound may be dispersed alone, but it may also be co-dispersed with an organic basic compound, the color development aid of the present invention, or other additives if necessary. If the organic basic compound used as a color developer is soluble in the water or organic solvent used as a solvent for the coating solution when applied to the support, the pH of the coating solution will increase, causing fogging on the background and deterioration of storage stability. Therefore, it is desirable to exist as a discontinuous fine particle dispersion in the coating layer, and the solubility in water at 20°C is 1.0.
g/ or less, the humidity and heat storage stability is good, and heterocyclic compounds such as aliphatic amines, pyrrolidine derivatives, imidazole derivatives, imidazoline derivatives, piperidine derivatives, etc. can also be suitably used, but in particular, the following general formula () When the hydrophobic guanidine derivatives () and () are used as a color developer, it is possible to obtain a fixed heat-sensitive recording material which has excellent storage stability under high temperature and high humidity conditions and which develops color with high sensitivity.
Further, as the color developer, one having a melting point in the range of 100 to 170°C can be particularly preferably used. The color developer may be dispersed alone using a dispersion means such as a ball mill, a sand grinder, an attritor, or the like, but it may also be co-dispersed with a coupler compound, the color development aid of the present invention, or other additives as necessary. General formula () General formula () [In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are hydrogen, alkyl having 18 or less carbon atoms, cyclic alkyl, aryl,
Represents aralkyl, amino, alkylamino, acylamino, carbamoylamino, heterocyclic residue,
R ₆ is lower alkylene, phenylene, naphthylene,
or

[Formula] (in the formula, X represents lower alkylene, SO ₂ , S ₂ , S, O, -NH- or a single bond), and the aryl group in the formula is lower alkyl, alkoxy, nitro, acylamino, alkylamino It also includes those having substituents selected from groups and halogens.] Typical examples are shown in Table 2, but the invention is not limited thereto. In the table

[Formula] represents a cyclohexyl group.

【formula】

【formula】

【formula】

【formula】

These guanidine derivatives shown above can be easily synthesized by known methods or methods similar thereto. In addition, examples of binder materials for forming the photosensitive and thermosensitive layer of the present invention include cornstarch, gum arabic, glue, gelatin, casein, methylcellulose, ethylcellulose, and aqueous solvents.
Starch or its modified products and derivatives such as hydroxyethyl cellulose, carboxymethyl cellulose, polyacrylamide, carboxymethyl starch, dialdehyde starch, polyvinyl alcohol or its modified products and derivatives, polyvinylpyrrolidone, isobutylene-maleic anhydride copolymer, polyacrylic acid Salt, styrene-maleic anhydride copolymer, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene-butadiene rubber (=SBR), methacrylate-butadiene rubber (=
MBR), nitrile butadiene rubber (=NBR), polymethyl methacrylate, polypropylene, polyacrylonitrile, synthetic resin emulsion such as acrylic ester, etc., and these binder materials can be used alone or in combination. Furthermore, in the case of an organic solvent system, the above-mentioned synthetic resin can be used by dissolving it in an organic solvent without emulsifying it. Since the coupling reaction of diazonium salts is promoted in polar solvents such as water, the storage stability of fixed heat-sensitive recording materials using diazonium salts, especially under high temperature and high humidity conditions, is limited by the use of binder materials with a low equilibrium moisture content. It can also be greatly improved by selecting
In addition, when using an aqueous solvent, water-resistant agents such as formalin, glyoxal, chromium alum, glutaraldehyde, melamine/formalin resin, urea/formalin resin, etc., which are usually used in water-soluble polymer binders, may be used. However, it is possible to improve the storage stability. Specific examples of pigments used in the photosensitive and heat-sensitive layer of the present invention include kaolin, calcined kaolin, talc, waxite, diatomaceous earth, styrene resin particles, calcium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium carbonate, Examples include titanium oxide, barium carbonate, urea-formalin filler, cellulose filler, aluminum oxide, etc., but from the viewpoint of thermal head matching properties such as scum and statesking, JP-A No. 53-118059, 54-25845,
The oil absorption as described in 54-118846, 54-118847 is
80ml to 500 according to the measurement method specified in JIS K 5101
It is preferable to use oil-absorbing pigments of ml/100g.
Particularly in the layer that is in direct contact with the heat head, it is desirable to use an oil-absorbing pigment exhibiting the above-mentioned oil absorption amount, such as calcined kaolin or urea-formalin filler. Other auxiliary ingredients include zinc chloride, zinc sulfate, sodium citrate, etc. to suppress or assist color development.
Saccharides such as guanidine thiourea sulfate, calcium gluconate, sorbitol, and sugar rose are used, and if necessary, UV inhibitors are added, and waxes and metal soaps are added to improve staining and color sensitivity. It can be used. Specific examples of waxes include paraffin wax, carnauba wax, microcrystalline wax, polyethylene wax, and higher fatty acid amides such as stearic acid amide, laurylamide, myristylamide, hardened tallow acid amide, and palmitin. Examples include acid amide, oleic acid amide, acetamide, coconut fatty acid amide, methylolated products of these fatty acid amides, methylene bis stearamide, ethylene bis stearamide, and higher fatty acid esters. Metal soaps include higher fatty acid polyvalent metal salts, namely zinc stearate, aluminum stearate,
Examples include calcium stearate and zinc oleate. These can be used alone as dispersed, but they can also be used as co-dispersed with organic basic compounds, coupler compounds, etc., and the color development aid of the present invention. In addition to paper, synthetic resin film,
Laminated paper can also be used, and when paper is used as a support, if the photosensitive and heat-sensitive layer is applied directly onto the support, the diazonium salt will penetrate into the pores of the paper base and be impregnated into the inside, so a large amount of diazonium will be absorbed. Since salt is required, the sensitivity of light fixing due to exposure after thermal printing may be reduced. To prevent this drawback, if necessary, silica sol,
It may be precoated with a void filler such as alumina, titanium oxide, kaolin, etc., or a combination of these and a polymeric material such as starch, casein, polyvinyl alcohol, polyvinyl acetate emulsion, etc., and then a photosensitive/thermosensitive layer may be applied. (E) Examples Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Example 1 A coating solution for a photosensitive and thermosensitive layer is prepared according to the following formulation, and coated onto a support so that the coated amount after drying is 9.0 g/m ² and dried to prepare a fixable thermosensitive recording material. The unit is parts by weight. Water 200 Citric acid 3.0 2,5-diethoxy-4-morpholinobenzenediazonium tetrafluoroborate 2 Calcined kaolin 10 Solution A 5 Solution B 100 10% polyvinyl alcohol 200 For solutions A and B, mix the following compositions in a ball mill. The mixture was prepared by pulverization and dispersion for 48 hours. Solution A 2-hydroxy-3-naphthoic acid-2'-ethoxyanilide 10g Ethylene glycol bis(P-benzyloxycarbonylphenyl) ether 10g 10% polyvinyl alcohol 5g Water 15g Solution B

[Formula] 100g (Compound (10) in Table 2) 10% methylcellulose 50g Water 150g Example 2 In Example 1, instead of using ethylene glycol bis(P-benzyloxycarbonylphenyl) ether in solution A, diethylene glycol bis( A fixable heat-sensitive recording material was prepared in the same manner as in Example 1 except that P-benzyloxycarbonylphenyl) ether was used. Example 3 In Example 1, 2-hydroxy-3-
A fixable heat-sensitive recording material was prepared in the same manner as in Example 1 except that 2-hydroxynaphthoic acid-4'-phenoxyanilide was used instead of naphthoic acid-2'-ethoxyanilide. Comparative Example 1 A fixable heat-sensitive recording material was prepared in the same manner as in Example 1 except that the ethylene glycol bis(P-benzyloxycarbonylphenyl) ether of the present invention was removed from Liquid A in Example 1. The thus obtained fixable heat-sensitive recording material was thermally printed using a facsimile machine (Toshiba KB-4800), and then the diazonium salt was decomposed and fixed by exposing the entire surface to ultraviolet light. The print density obtained as described above was measured using a Macbeth densitometer (RD-514). Table the value -
Shown in 3. Table 3 also shows the results of the storage stability test. The storage stability test represents the results of a humidity and heat resistance test when a sample formed by preparing a coating solution, applying it and drying it was left in a dark place at 40℃ and 90% relative humidity for 24 hours. After fixation, the skin density measured with a Macbeth densitometer is shown in Table 3.

[Table] Example 4 A layer containing a diazonium salt is prepared according to the following formulation and coated on a support so that the coating weight after drying is 2.0 g/m ² . Citric acid 2g Thiourea 2g 2,5-diethoxy-4-morpholinobenzenediazonium tetrafluoroborate 2g Calcined kaolin 4g 10% polyvinyl alcohol 30g Water 100ml Contains a color developer prepared with the following formulation on the layer created above. The coating amount of the coating layer after drying is
A fixing type heat-sensitive recording material is prepared by applying it at a concentration of 8.0 g/m ² . Water 100g Calcined kaolin 20g Part A 5g Part B 100g 10% polyvinyl alcohol 120g 50% melamine formalin waterproofing agent 2g For parts A and B, the same formulation as in Example 1 was ground and dispersed in a ball mill for 48 hours. Prepared. Example 5 A fixable heat-sensitive recording material was prepared in the same manner as in Example 4, except that the formulations of liquid A and liquid B were the same as in Example 2. Example 6 A fixable heat-sensitive recording material was prepared in the same manner as in Example 4, except that the formulations of liquid A and liquid B were the same as in Example 3. Comparative Example 2 A fixable heat-sensitive recording material was prepared in the same manner as in Example 4, except that the formulations of liquid A and liquid B were the same as in comparative example 1. The thus obtained diazo-fixed heat-sensitive recording material was thermally printed using a facsimile (Toshiba KD-4800), and then the entire surface was exposed to ultraviolet light to decompose and fix the diazonium salt. The print density obtained as described above was measured using a Macbeth densitometer (RD-514), and the values are shown in Table 4.
Shown below. Table 4 also shows the results of the storage stability test. The storage stability test consists of a moisture and heat resistance test in which the sample is prepared by preparing the coating solution, applied and dried, and left in a dark place at 40℃ and 90% relative humidity for 24 hours.
Table 4 shows the results of a heat resistance test in which the samples were left in a dryer at ℃ for 24 hours. After each treatment, the entire surface was exposed to light and fixed, and the background density was measured using a Macbeth densitometer.

[Table] (F) Effects of the Invention As shown in Tables 3 and 4, by adding the compound represented by the general formula () of the present invention to a fixing type heat-sensitive recording material, color can be developed with high density, and It was possible to obtain a fixable heat-sensitive recording material with excellent storage stability.

Claims (1)

[Scope of Claims] 1. A fine particle dispersion of a diazonium salt, a coupler compound, a coloring aid, and an organic basic compound that melts with heat and exhibits a basic atmosphere as a color developer in the same layer or in two or more layers. A fixing heat-sensitive recording material provided on a support as a photosensitive heat-sensitive layer consisting of a separate layer, wherein the coloring aid is a compound represented by the following general formula (). General formula () (In the formula, R represents an alkyl group or an aralkyl group, and n represents an integer of 1 to 3). 2. Claim 1, in which at least one of the diazonium salt and the coupler compound is contained in the light and heat sensitive layer as a discontinuous fine particle dispersion.
The fixing type heat-sensitive recording material described in Section 1. 3. The fixable heat-sensitive recording material according to claim 2, wherein the organic basic compound is a hydrophobic guanidine derivative represented by the following general formula () or (). General formula () General formula () (In the formula, R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are hydrogen, alkyl having 18 or less carbon atoms, cyclic alkyl, aryl,
Represents aralkyl, amino, alkylamino, acylamino, carbamoylamino, heterocyclic residue,
R ₆ represents lower alkylene, phenylene, naphthylene, or [Formula] (wherein X represents lower alkylene, SO ₂ , S ₂ , S, O, -NH-, or a single bond), and the aryl group in the formula is lower Also included are those having substituents selected from alkyl, alkoxy, nitro, acylamino, alkylamino groups and halogen. ).