JP2006130931A - Manufacturing method for heat-sensitive recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method which enables the stable manufacture of a heat-sensitive recording material which is excellent in chemical resistance and water resistance, and at the same time, has favorable surface characteristics, prevents the sticking of a thermal head or the like from occurring at the time of printing, and can form an image of a high picture quality. <P>SOLUTION: This manufacturing method for the heat-sensitive recording material comprises three processes. In the first process (1), a water-soluble resin and a component represented by general formula (C), are stirred while being heated in water, and a water-soluble resin solution is prepared. In the second process (2), a solid component or a liquid component is additionally added to the water-soluble resin solution, and an application liquid is prepared. In the third process (3), the application liquid is applied on a supporting body, and is dried to form a layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a heat-sensitive recording material, and more specifically, a heat-sensitive recording material having a uniform coating surface, excellent chemical resistance and the like, little sticking and covering with a thermal head, and good image quality. It relates to a manufacturing method.

  Thermosensitive recording materials are inexpensive and their recording devices are compact and easy to maintain, such as facsimile machines and various printers, and thus have been used in a wide range of fields. By the way, since the heat-sensitive recording material is generally inferior in water resistance, chemical resistance, plasticizer resistance, etc., for example, when the color image is brought into contact with water, oil, a plasticizer contained in plastic, the image density May be significantly reduced. Further, since the surface properties are not uniform, sticking may occur and the image may be deteriorated.

  In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. 59-106995 discloses a polyvinyl alcohol resin having an acetoacetylated polyvinyl alcohol resin and / or at least acrylonitrile as a copolymer component on the heat-sensitive recording layer. There has been proposed a technique for improving the water resistance of a heat-sensitive recording material by providing a protective layer containing as a main component. Japanese Patent Application Laid-Open No. 5-262020 proposes a technique for improving the storability of an image by containing polyvinyl alcohol having a specific structure in a heat-sensitive recording layer.

However, the coating solution containing the water-soluble resin has a problem that it cannot be stably applied because the viscosity rapidly increases. In addition, there is a drawback that the water-soluble resin gels in the solution and the life of the coating solution is short. Furthermore, when a protective layer or the like is actually produced using these coating liquids, a part of the binder in the coating liquid may be insolubilized. As a result, the surface of the protective layer or the like may be uneven, and the heat-sensitive recording material The surface properties may be deteriorated. Deterioration of the surface property causes a surface defect or the like due to sticking of a thermal head or the like during printing, leading to a decrease in image quality.
Japanese Patent Publication No. 1-17479 proposes a method for adjusting the surface tension by adding alkylsulfosuccinate to the protective layer in order to improve sticking caused by remarkable cissing marks on the coated surface. Yes. However, in such a method, when a water-soluble resin having high crystallinity such as PVA having a high saponification degree is used, a part of PVA is deposited in the coating solution over time, so that a uniform surface property layer is formed. I can't.

  The present invention stably produces a heat-sensitive recording material that is excellent in chemical resistance and water resistance, has good surface properties, does not cause sticking such as a thermal head during printing, and can form a high-quality image. An object is to provide a production method.

In order to solve the above-described problems, the method for producing a thermosensitive recording material of the present invention has the following configuration.
(1) a step of preparing a water-soluble resin solution by stirring a water-soluble resin and a compound represented by the following general formula (C) while heating in water;
(2) adding a solid or liquid component to the water-soluble resin solution to prepare a coating solution;
(3) A method for producing a heat-sensitive recording material, comprising: applying the coating liquid onto a support and drying to form a layer.

In the general formula (C), R ³ represents an alkyl group having 8 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 6 to 20 carbon atoms. R ⁴ represents H or — (CH ₂ ) _m —OSO ₃ X. X represents an alkali metal, ammonium, or alkanol ammonium. n represents an integer of 3 to 20, and m represents an integer of 0 to 6.

  According to the present invention, it is possible to stably produce a heat-sensitive recording material that has good surface properties, does not cause sticking of a thermal head or the like during printing, and can form a high-quality image.

<< 1. Thermal recording material >>
The heat-sensitive recording material of the present invention is a heat-sensitive recording material in which one or more layers are provided on a support, and at least one layer contains a water-soluble resin and a stabilizer. As a stabilizer, the following (I) is used as an essential component, and the following (II) is used as an optional component.
(I) Compound represented by general formula (C) (II) Compound represented by general formula (A) and compound represented by general formula (B) These stabilizers stabilize a water-soluble resin in a dissolved state. And has a function of preventing the water-soluble resin from aggregating and precipitating. Therefore, the protective layer and the recording layer containing the stabilizer do not cause aggregation of the water-soluble resin, and the layer surface is a heat-sensitive recording material having high smoothness.

The stabilizers (I) and (II) will be described below.
<(I) Compound Represented by General Formula (C)>

In the general formula (C), R ³ represents an alkyl group having 8 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 6 to 20 carbon atoms. When the number of carbon atoms is 7 or less, the stability of the coating solution decreases, and when the number is 21 or more, the water solubility of the stabilizer decreases, which is not preferable. The alkyl group may be linear or branched. Examples of the alkyl group, aryl group, and aralkyl group include octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, nonylphenyl group, dodecylphenyl group, octylnaphthyl group, and the like. The alkyl group, aryl group, and aralkyl group may have a substituent, and examples of the substituent include lower alkyl groups such as a methyl group and an ethyl group.
R ⁴ represents H or — (CH ₂ ) _m —OSO ₃ X. X represents a monovalent alkali metal, ammonium or alkanol ammonium, and is the same as M in formula (A). n shows the integer of 3-20, Preferably it is 7-18. m shows the integer of 0-6, Preferably, it is 2-4.

<(II). Compound Represented by General Formula (A) and Compound Represented by General Formula (B)>

In the general formula (A), R ⁰ and R ¹ represent an alkyl group having 6 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 6 to 20 carbon atoms. When the number of carbon atoms is 5 or less, the stability is lowered, and when the number of carbon atoms is 21 or more, the water solubility of the stabilizer is lowered. The alkyl group may be linear or branched. Examples of the alkyl group, aryl group, and aralkyl group include hexyl group, octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, nonylphenyl group, dodecylphenyl group, and octylnaphthyl group. . The alkyl group, aryl group, and aralkyl group may have a substituent, and examples of the substituent include lower alkyl groups such as a methyl group and an ethyl group.

M is any of an alkali metal (Na, K, Li, etc.), an ammonium group (NH ₄ —), an alkyl ammonium group (R ¹⁰ —NH ₃ —), or an alkanol ammonium group (—R ¹¹ (OH) NH ₃ —). Represents. Examples of the alkyl group (R ¹⁰ ) of the alkylammonium group include a methyl group, an ethyl group, and a propyl group. Further, the alkylene group of alkanol ammonium group (R ^11), include alkylene groups having a structure obtained by removing one hydrogen atom from exemplified alkyl group with an alkyl ammonium group.

In General Formula (B), R ² represents an alkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 6 to 20 carbon atoms. The alkyl group may be linear or branched. Examples of alkyl groups, aryl groups, and aralkyl groups include propyl group, hexyl group, octyl group, 2-ethylhexyl group, decyl group, dodecyl group, octadecyl group, nonylphenyl group, dodecylphenyl group, octylnaphthyl group, etc. Can be mentioned. The alkyl group, aryl group, and aralkyl group may have a substituent, and examples of the substituent include lower alkyl groups such as a methyl group and an ethyl group.

  The solid content of the stabilizer is preferably from 0.01% by weight to 10% by weight, particularly preferably from 0.1% by weight to 5% by weight, based on the water-soluble resin. When a stabilizer is added at this ratio, the water-soluble resin can be stabilized efficiently. When the compound represented by the general formula (A) and the compound represented by the general formula (B) are used in combination as an optional component of the stabilizer, the ratio is 97/3 to 20/80 by weight. It is preferable that it is 96/4-30/70. When the weight ratio of the compound represented by the general formula (B) is lower than this range, the stability of the coating solution is lowered, and when it is larger than this range, the wettability is lowered. This can be improved by increasing the solids content of the total stabilizer, but will result in increased manufacturing costs.

  Conventionally known materials can be widely used as the water-soluble resin. For example, polyvinyl alcohol, ethylene-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, vinyl acetate-acrylamide copolymer, silicon-modified polyvinyl alcohol, starch, modified starch, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, gelatins, gum arabic, casein , Styrene-maleic acid copolymer hydrolyzate, styrene-maleic acid copolymer half ester hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyacrylamide derivative, polyvinyl pyrrolidone, polystyrene sulfonate soda, alginic acid Examples include soda. As the coating solution for the heat-sensitive recording material, a polyvinyl alcohol-based resin is preferable, and ethylene-modified polyvinyl alcohol is particularly preferable.

  When a coating solution is prepared using a water-soluble resin having high crystallinity, the water resistance and chemical resistance of a layer produced using the coating solution are improved. Accordingly, when the water-sensitive recording material is required to have high water resistance, it is preferable to use a water-soluble resin having high crystallinity. Since the crystallinity of the water-soluble resin varies depending on the degree of polymerization or saponification of the resin, the crystallinity of the resin may be adjusted by setting these values to appropriate values. For example, in the case of polyvinyl alcohol, the crystallinity changes depending on the degree of saponification and the degree of ethylene modification. When ethylene-modified polyvinyl alcohol is used as the water-soluble resin, those having a saponification degree of 80% mol or more are preferable because the crystallinity becomes high. Particularly preferably, it is 88% mol or more and 99.8% mol or less.

  When ethylene-modified polyvinyl alcohol is used as the water-soluble resin, the degree of ethylene modification is preferably 1 mol% to 20 mol%, particularly preferably 4 mol% to 12 mol%. When the degree of ethylene modification is less than this range, the water resistance decreases, and when it exceeds this range, the water solubility decreases. The ethylene-modified polyvinyl alcohol may be further modified with other functional groups as long as it does not adversely affect the properties and coating solution stability. Specific examples of the other functional group include a carboxyl group, a terminal alkyl group, an amino group, a sulfonic acid group, a terminal thiol group, a silanol group, and an amide group. Among these, carboxyl group-modified, amino group-modified sulfonic acid groups and the like are effective from the viewpoint of imparting solubility to the ethylene-modified polyvinyl alcohol.

  The heat-sensitive recording material of the present invention has a single-layer structure in which only a heat-sensitive recording layer is formed on a support, a two-layer structure in which a protective layer is further provided thereon, and a multicolor multilayer having a plurality of heat-sensitive recording layers. Any of the heat-sensitive recording materials having a structure and a multilayer structure in which an intermediate layer is provided between two or more heat-sensitive recording layers may be used. When the heat-sensitive recording material has a single-layer structure, the layer contains the water-soluble resin and the stabilizer, and when the heat-sensitive recording material has a multilayer structure having two or more layers, the water-soluble recording material has one or more layers. A heat-sensitive recording material containing a resin and the stabilizer. It is only necessary that at least one of the layers constituting the heat-sensitive recording material (which may be any of a protective layer, a heat-sensitive recording layer, and an intermediate layer) contains the water-soluble resin and the stabilizer. Among these, it is preferable that the protective layer, which is the outermost surface layer, contains the water-soluble resin and the stabilizer because the sticking of the thermal head can be most effectively prevented.

The water-soluble resin is a binder for forming a layer. Depending on the purpose of each layer, other components are mixed into the water-soluble resin.
Hereinafter, the thermal recording layer, the protective layer, and the intermediate layer will be described.
<Thermal recording layer>
The heat-sensitive recording layer contains at least a coloring component that develops color when heated. Examples of the coloring component include the following.
(A) A combination of an electron donating dye precursor and an electron accepting compound.
(B) A combination of a diazo compound and a coupler.
(C) A combination of an organic metal salt such as silver behenate or silver stearate and a reducing agent such as protocatechinic acid, spiroindane or hydroquinone.
(D) A combination of a long-chain aliphatic salt such as ferric stearate or ferric myristate and a phenol such as gallic acid or ammonium salicylate.

(E) Organic acid heavy metal salts such as nickel, cobalt, lead, copper, iron, mercury and silver salts such as acetic acid, stearic acid and palmitic acid, and alkaline earth metals such as calcium sulfide, strontium sulfide and potassium sulfide A combination of a sulfide or a combination of the organic acid heavy metal salt and an organic chelating agent such as s-diphenylcarbazide or diphenylcarbazone.
(F) Combinations of heavy metals such as silver, lead and mercury, sulfates of alkali metals such as sodium, and sulfur compounds such as Na-tetrathionate, sodium thiosulfate and thiourea.

(G) A combination of an aliphatic ferric salt such as ferric stearin and an aromatic polyhydroxy compound such as 3,4-hydroxytetraphenylmethane.
(H) A combination of an organic noble metal salt such as oxalate or mercury oxalate and an organic polyhydroxy compound such as polyhydroxy alcohol, glycerin or glycol.
(I) A combination of an aliphatic ferric salt such as ferric pelargonate or ferric laurate and a thiocesylcarbamide or isothiocecilcarbamide derivative.

(Nu) A combination of an organic acid lead salt such as lead caproate, lead pelargonate or lead behenate and a thiourea derivative such as ethylenethiourea or N-dodecylthiourea.
(L) A combination of a higher fatty acid heavy metal salt such as ferric stearate and copper stearate and zinc dialkyldithiocarbamate.
(V) Those that form an oxazine dye such as a combination of resorcin and a nitroso compound.
(W) A combination of a formazan compound and a reducing agent and / or a metal salt.

Among these, in the present invention, (i) a combination of an electron donating dye precursor and an electron accepting compound, (b) a combination of a diazo compound and a coupler, and (c) an organometallic salt and a reducing agent. A combination is preferable, and the case of (A) and (B) is particularly preferable. The hue exhibited by these color developing components is mainly due to the structure of the dye produced by the reaction of each of the combined compounds (for example, in the case of (b), a diazo dye produced by a coupling reaction between a diazo compound and a coupler). To be determined. Accordingly, the chemical structure of the compound to be combined may be appropriately selected so as to generate a dye that develops a desired hue.
Hereinafter, each of (A) to (C) will be described with reference to exemplified compounds.

((A) Combination of electron-donating dye precursor and electron-accepting compound)
-Electron-donating dye precursor-
The electron donating dye precursor has a property of coloring by donating electrons or accepting protons such as acids, and has a partial skeleton such as lactone, lactam, sultone, spiropyran, ester and amide. And a compound in which these partial skeletons are ring-opened or cleaved upon contact with an electron-accepting compound which is a developer. For example, phthalide compounds such as triphenylmethane phthalide and indolyl phthalide, fluoran compounds, phenothiazine compounds, leucooramine compounds, rhodamine lactam compounds, triphenylmethane compounds, triazene compounds, spirodipyran compounds And various electron donating colorless dye compounds such as pyridine compounds, pyrazine compounds and fluorene compounds.

Specific examples of the phthalide-based compound include U.S. Reissue Patent No. 23,024, U.S. Pat. Nos. 3,491,111, 3,491,112, and 3,491,116. No. 3,509,174 and the like.
Specific examples of the fluorane compound include, for example, U.S. Pat. Nos. 3,624,107, 3,627,787, 3,641,011, and 3,462,828. No. 3,681,390, No. 3,920,510, No. 3,959,571 and the like.
Specific examples of the spirodipyran compound include those described in US Pat. No. 3,971,808.
Specific examples of the pyridine-based compound and the pyrazine-based compound include those described in, for example, US Pat. Nos. 3,775,424, 3,853,869, and 4,246,318. Is mentioned.
Specific examples of the fluorene compound include those described in JP-A-63-94878.

-Electron acceptor-
Examples of the electron-accepting substance include conventionally known compounds such as phenol derivatives, salicylic acid derivatives, metal salts of aromatic carboxylic acids, acidic clay, bentonite, novolac resins, metal-treated novolac resins, and metal complexes. Examples of these are Japanese Patent Publication Nos. 40-9309, 45-14039, Japanese Patent Application Laid-Open Nos. 562-140483, 48-51510, 57-210886, and 58-87089. , 59-11286, 60-76795, 61-95988, and the like.

Specific examples thereof include 4-t-butylphenol, 4-phenylphenol, 2,2'-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 4,4'-sec- Butylidenediphenol, 4,4′-cyclohexylidenediphenol, 4-hydroxyphenyl-3 ′, 4′dimethylphenylsulfone, 4- (4-isopropoxyphenylsulfonyl) phenol, 4,4′-dihydroxydiphenyl Sulfide, 1,4-bis- (4′-hydroxycumyl) benzene, 1,3-bis- (4′-hydroxycumyl) benzene, 4,4′-thiobis (6-tert-butyl-3-methyl) Phenol), 4-hydroxybenzoic acid benzyl ester, 3,5-di-t-butylsalicylic acid, 3-phenyl-5- ( , Α-dimethylbenzyl) salicylic acid, 3-cumyl-5-t-octylsalicylic acid, 3,5-di-t-butylsalicylic acid, 3-phenyl-5-t-octylsalicylic acid, 3-methyl-5-α-methyl Benzylsalicylic acid, 3-methyl-5-cumylsalicylic acid, 3,5-di-t-octylsalicylic acid, 3,5-bis (α-methylbenzyl) salicylic acid, 3-cumyl-5-phenylsalicylic acid, 5-n- Octadecylsalicylic acid, 4-pentadecylsalicylic acid, 3,5-bis (α, α-dimethylbenzyl) salicylic acid, 3,5-bis-t-octylsalicylic acid, 4-β-dodecyloxyethoxysalicylic acid, 4-methoxy-6 Dodecyloxysalicylic acid, 4-β-phenoxyethoxysalicylic acid, 4-β-p-ethylphenoxyethoxysalicylic acid 4-beta-p-methoxyphenoxy, etc. ethoxy salicylic acid and the like metal salts thereof.
These may be used individually by 1 type and may use 2 or more types together.

The amount of the electron accepting substance used is preferably 50 to 800% by weight, more preferably 100 to 500% by weight, based on the electron donating dye precursor. Even if the amount used exceeds 800% by weight, an effect commensurate with the addition of a large amount of the electron-accepting substance cannot be obtained, and if it is less than 50% by weight, color development may be insufficient. .
When mixing an electron-accepting substance and an electron-donating dye precursor in a water-soluble resin aqueous solution as a coloring component, mix the electron-accepting substance and the electron-donating dye precursor in the same water-soluble resin aqueous solution. Alternatively, each of them may be mixed with an aqueous solution of a water-soluble resin, and the obtained two mixed solutions may be further mixed. In addition, you may mix components, such as coloring aid.

((B) Combination of diazo compound and coupler)
-Diazo compounds-
As diazo compounds, those that react with couplers to develop color can be widely used, but when applied to heat-sensitive recording materials for photofixing, photodegradable diazo compounds that decompose when receiving light of a specific wavelength Is preferred. Examples of such diazo compounds include aromatic diazonium salts, diazosulfonate compounds, and diazoamino compounds. Specific examples of the diazo compound include JP-A-60-184880, JP-A-61-217289, JP-A-2-147285, JP-A-5-297024, JP-A-5-122865, and JP-A-5-122865. -278608 etc. and the compound described in the example etc. are mentioned suitably.

  For example, 1-diazo-4-dimethylaminobenzene, 1-diazo-4-N-methyl-Nn-dodecylaminobenzene, 1-diazo-4-N-ethyl-Nn-dodecylaminobenzene, 1- Diazo-4-morpholinobenzene, 1-diazo-4-methylbenzylaminobenzene, 1-diazo-4-N-ethyl-N- (2-hydroxyethyl) aminobenzene, 1-diazo-2-methoxy-4-diethylamino Benzene, 1-diazo-2-n-butoxy-4-di-n-butylaminobenzene, 1-diazo-2-n-hexyloxy-4-di-n-hexylaminobenzene, 1-diazo-2-n -Octyloxy-4-di-n-octylaminobenzene, 1-diazo-2-n-hexyloxy-4-bis (2-cyanoethylamino) benzene, 1 Diazo-2-n-hexyloxy-4-Nn-hexyl-N- (1-methyl-2-p-methoxyphenoxyethylamino) benzene, 1-diazo-5-butoxy-2-chloro-4 -Dimethylaminobenzene, 1-diazo-5-methoxy-2-chloro-4-piperazinobenzene, 1-diazo-4-morpholino-2,5-dibutoxybenzene, 1-diazo-4-pyrrolidino-3- Methoxybenzene, 1-diazo-4- (2-ethylhexanoylpiperidino) -2,5-dibutoxybenzene, 1-diazo-4- [α- (2,4-ditert-amylphenoxy) butyrylpi Peridino] benzene, 1-diazo-2-N, N-diethylcarbamoyl-5-ethoxy-4-diethylaminobenzene, 1-diazo-2-p-tolylthio-5-phenoxy- 4-diethylaminobenzene, 4-diazo-4'-methoxystilbene, 1-diazo-4-p-tolylthio-2,5-diethoxybenzene, 1-diazo-4-p-tolylthio-2,5-di-n -Butoxybenzene, 1-diazo-4- (p-chlorophenylthio) -2,5-di-n-butoxybenzene, 1-diazo-4- (p-chlorophenylthio) -2,5-di-n -Butoxybenzene, 1-diazo-4- (p-chlorophenylthio) -2,5-di-n-pentyloxybenzene, 1-diazo-4- (4-methoxyphenylthio) -2,5-diethoxy Benzene, 1-diazo-4- (N, N-dioctylaminocarbonyl) benzene, 1-diazo-4- (4-t-octylphenoxy) benzene, 1-diazo-4- (4-methoxybenzamido) ) Such as 2,5-diethoxy benzene.

  The diazo compound is preferably contained in the coating liquid in the form of a diazonium salt with an acid anion. Examples of the counter anion include polyfluoroalkylcarboxylic acids having 1 to 9 carbon atoms, and those having 1 to 9 carbon atoms. Examples thereof include polyfluoroalkyl sulfonic acid, boron tetrafluoride, tetraphenyl boron, hexafluorophosphoric acid, aromatic carboxylic acid, and aromatic sulfonic acid anion. A diazo compound may be used individually by 1 type, and may use 2 or more types together.

-Coupler-
The coupler is not particularly limited as long as it forms a dye by coupling with a diazo compound in a basic atmosphere, and any compound can be used. For example, those described in JP-A-1-67379, 2-54250, 4-53794, Japanese Patent Application No. 6-18669, 6-18670 and the like are preferable. Specifically, resorcin, phloroglucin, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, 1,5-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 2,3-dihydroxy-6-sulfonylnaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid anilide, 5,5-dimethyl- 1,3-cyclohexanedione, 1,3-cyclopentanedione, 5- (2-n-tetradecyloxyphenyl) -1,3-cyclohexanedione, 5-phenyl-4-methoxycarbonyl-1,3-cyclohexane Dione, 5- (2,5-di-n-octyloxyf Nyl) -1,3-cyclohexanedione, 1,3-dicyclohexylbarbituric acid, 1,3-di-n-dodecylbarbituric acid, 1-n-octyl-3-n-octadecylbarbituric acid, 1-phenyl -3- (2,5-di-n-octyloxyphenyl) barbituric acid, 1-phenyl-3-methyl-5-pyrazolone, 1- (2,4,6-trichlorophenyl) -3-anilino- 5-pyrazolone, 6-hydroxy-4-methyl-3-cyano-1- (2-ethylhexyl) 2-pyridone, 2- [3- [α- (2,4-di-t-amylphenoxy) butanamide] benzamide ] Phenol, 2,4-bis- (benzoylacetamino) toluene, 1,3-bis- (pivaloylacetaminomethyl) benzene, benzoylacetonitrile, te Noylacetonitrile, acetoacetanilide, benzoylacetanilide, pivaloylacetanilide, 2,5-di-n-heptyloxy-1-acetoacetamidebenzene, 2,5-di-n-butoxy-1-pivaloylacetamidebenzene, 2 -Chloro-5- (Nn-butylsulfamoyl) -1-pivaloylacetamidobenzene, 2 ', 5'-di-n-heptyloxybenzamide, 1- (4-n-octyloxyphenyl) -3-t-butyl-5-aminopyrazole and the like.

For the purpose of promoting the coupling reaction between the diazo compound and the coupler, an organic basic substance may be used in combination. Examples of basic substances are described in Japanese Patent Application No. 63-23490, Japanese Patent Application Laid-Open No. 1-63187, and the like. Examples of the basic substance include nitrogen-containing compounds such as tertiary amines, piperidines, piperazines, amidines, formamidines, pyridines, guanidines and morpholines. Specifically, N, N ^'- bis (3-phenoxy-2-hydroxypropyl) piperazine, N, ^N' - bis [3- (p-methylphenoxy) -2-hydroxypropyl] piperazine, N, N ^' - bis [3- (p-methoxyphenoxy) -2-hydroxypropyl] piperazine, N, N ^'- bis (3-phenylthio-2-hydroxypropyl) piperazine, N, ^N' - bis [3- (beta Nafutokishi) -2-hydroxypropyl] piperazine, N-3- (beta Nafutokishi) -2-hydroxypropyl -N ^'- methylpiperazine, 1,4-bis {[3- (N- methylpiperazino) -2-hydroxy] propyloxy} Piperazines such as benzene, N- [3- (β-naphthoxy) -2-hydroxy] propylmorpholine, 1,4-bis [(3-morpholine -2-Hydroxy) propyloxy] benzene, 1,3-bis [(3-morpholino-2-hydroxy) propyloxy] benzene and other morpholines, N- (3-phenoxy-2-hydroxypropyl) piperidine, N- Preferred examples include piperidines such as dodecylpiperidine, and guanidines such as triphenylguanidine, tricyclohexylguanidine and dicyclohexylphenylguanidine. These may be used individually by 1 type and may use 2 or more types together.

When a diazo compound and a coupler are mixed in an aqueous solution of a water-soluble resin as a coloring component, the diazo compound is microencapsulated so that the diazo compound and the coupler do not react at room temperature to form a color. It is preferable to add to the aqueous solution of the resin. For example, a diazo compound is microencapsulated, and the obtained microcapsule (including a diazo compound) is mixed with an aqueous solution of a water-soluble resin. Separately, a coupler and a basic compound are mixed in an aqueous solution of a water-soluble resin and emulsified with an appropriate emulsification aid. Then, two types of liquid mixture can be mixed and a coating liquid can be manufactured. As a microencapsulation method, a generally used method can be widely used. For example, a method described in JP-A-2-141279 is preferably used.
The blending ratio of the coupler and the diazo compound is preferably 0.1 to 30 parts by weight of the coupler with respect to 1 part by weight of the diazo compound, and further 0.1 to 0.1 parts by weight of the basic substance with respect to 1 part by weight of the diazo compound. It is preferably 30 parts by weight.

((C) Combination of organometallic salt and reducing agent)
Specific examples of the organometallic salt in the combination of the organometallic salt and the reducing agent include long chain aliphatics such as silver laurate, myristic acetate, silver palmitate, silver stearate, silver arachin vinegar and silver behen vinegar. Silver salt of carboxylic acid, silver salt of benzotriazole, silver salt of benzimidazole, silver salt of carbazole and silver of organic compound having imino group such as silver salt of phthalazinone, silver of sulfur-containing compound such as s-alkylthioglycolate Salt, silver salt of aromatic carboxylic acid such as silver benzoate and silver phthalate, silver salt of sulfonic acid such as silver ethanesulfonate, silver salt of sulfinic acid such as silver o-toluenesulfinate, phenyl phosphorus There are silver salts of phosphoric acid such as silver acid, silver barbiturate, silver saccharinate, silver salt of salicylaldoxime and any mixtures thereof. Among these compounds, long-chain aliphatic carboxylic acid silver salts are preferable, and silver behenate is particularly preferable. Further, behenic acid may be used together with silver behenate.

The reducing agent can be suitably used based on the description in JP-A-53-1020, page 227, lower left column, line 14 to page 229, upper right column, line 11; Tris or tetrakisphenols, mono or bisnaphthols, di or polyhydroxynaphthalenes, di or polyhydroxybenzenes, hydroxy monoethers, ascorbic acids, 3-pyrazolidones, pyrazolines, pyrazolones, reducing sugars, Preference is given to using phenylenediamines, hydroxylamines, reductones, hydrooxamines, hydrazides, amide oximes, N-hydroxyureas and the like.
Among these compounds, particularly preferred are aromatic organic reducing agents such as polyphenols, sulfonamidephenols and naphthols.

  In addition, the heat-sensitive recording layer has a heat-fusible substance, an ultraviolet absorber, a pigment, a sensitizer, a wax, an antistatic agent, an antifoaming agent, a conductive agent, a fluorescent dye, an interface depending on the use of the heat-sensitive recording material. An activator, a UV absorber precursor or the like can also be added.

<Protective layer>
The protective layer can contain pigments, lubricants, surfactants, dispersants, fluorescent brighteners, metal soaps, ultraviolet absorbers, ultraviolet absorber precursors, and the like depending on the application of the heat-sensitive recording material.
Examples of the pigment include known organic or inorganic pigments. Specific examples include calcium carbonate, aluminum hydroxide, barium sulfate, titanium oxide, talc, wax, kaolin, calcined kaolin, amorphous silica, urea formalin resin powder, polyethylene resin powder, and benzoguanamine resin powder. These may be used individually by 1 type and may use 2 or more types together.
Preferred examples of the lubricant include zinc stearate, calcium stearate, paraffin wax, polyethylene wax and the like.
Preferred examples of the surfactant include a fluorine-based surfactant.

<Intermediate layer>
In the intermediate layer, depending on the use of the heat-sensitive recording material, etc., as in the case of the coating liquid for the protective layer, a pigment, a lubricant, a surfactant, a dispersant, a fluorescent brightener, a metal soap, an ultraviolet absorber, An ultraviolet absorber precursor or the like can be contained.

<Support>
As the support, acid paper, neutral paper, coated paper, plastic film laminated paper, synthetic paper, plastic film, or the like is used. An undercoat layer may be provided on the support. In this case, the undercoat layer may be a layer containing the water-soluble resin and the stabilizer.

<Multicolor thermal recording material>
Details of the multicolor heat-sensitive recording materials are described in, for example, JP-A-4-135787, JP-A-4-144784, JP-A-4-144785, JP-A-4-194842, and JP-A-4-247447. 4-247448, 4-340540, 4-340541, 5-34860, and the like. These multicolor thermosensitive recording materials have a multilayer structure, and are laminated with thermosensitive recording layers that develop colors in different hues. If the color hue of each heat-sensitive recording layer is selected to be the three primary colors in subtractive color mixing, that is, yellow, magenta and cyan, full-color image recording is possible. The heat-sensitive recording layer and intermediate layer may contain the stabilizer together with the water-soluble resin, but it is particularly preferable that the protective layer contains the water-soluble resin and the stabilizer.

≪2. Method for producing thermal recording material >>
The heat-sensitive recording material of the present invention can be produced by preparing a coating solution, applying the coating solution on a support, and drying to form a layer. Depending on the order of application and the number of times of application, heat-sensitive recording materials having various configurations of a single layer structure to a multilayer structure can be produced. Preparation of the coating liquid containing the water-soluble resin and the stabilizer is carried out by using a water-soluble resin, a stabilizer and other components (for example, a coloring component when preparing a coating liquid for a heat-sensitive recording layer). Although it may be carried out by stirring in water at the same time, it is preferable to prepare by the following steps because the stability of the coating solution and the surface properties of the layer to be produced are improved.

First, (1) a water-soluble resin and a stabilizer are heated and stirred in water to prepare a water-soluble resin solution, and then (2) a solid or liquid component is further added to the water-soluble resin solution. Prepare the coating solution.
In the step (1), after the stabilizer and the water-soluble resin are mixed, water is added to the mixture, or the stabilizer and the water-soluble resin are separately added to water. After the addition, the mixture is stirred so that the stabilizer and the water-soluble resin are sufficiently dispersed in water, and further stirred while heating to obtain an aqueous solution of the water-soluble resin. Heating may be performed simultaneously with the start of stirring, or stirring may be performed at room temperature to uniformly disperse the water-soluble resin, and then heating may be started. The latter is preferable because the water-soluble resin can be stirred without being aggregated and precipitated in water. The higher the heating temperature, the better the efficiency of adjusting the coating liquid, but it is preferable. However, if the heating temperature is too high, saponification of the water-soluble resin proceeds and the water-soluble resin may precipitate. Heating is preferably performed at 80 ° C. or higher and 100 ° C. or lower.

  By heating and mixing in this way, the liquid life of the aqueous solution of the water-soluble resin is prolonged. Therefore, even when it is necessary to store the water-soluble resin solution by the step (2), the water-soluble resin or the like is not precipitated, and a coating liquid having good liquid properties can be obtained. Furthermore, the storage stability of the coating solution produced through the step (2) is also improved.

  In the step (2), a solid or liquid component is mixed with the aqueous solution of the water-soluble resin. The solid or liquid component is selected according to the application of the coating solution. For example, in the case of a thermal recording layer coating solution, a coloring component and other additives such as a sensitizer, surfactant, antifoggant, slip agent, etc., for a protective layer and intermediate layer coating solution. Include pigments, ultraviolet absorbers, and the above additives. The solid component may be in the solid state of powder or crystal. The liquid component may be in any liquid state such as a uniform liquid, a dispersion liquid, and an emulsion liquid. In order to mix the solid or liquid components in the aqueous solution of the water-soluble resin, it can be uniformly mixed using a known mixing device such as a mixer, a dissolver, an attritor, and a sand mill.

  Each layer is formed by applying the coating solution for each layer obtained by the above method onto the support (both when applied directly and when applied via another layer) and drying. be able to. The coating liquid can be applied according to a method such as a bar coater method, an air knife coater method, a blade coater method, a gravure coater method, a spray coater method, a dip coater method, or a curtain coater method. Among these, a curtain coater method is preferable, and a free-fall curtain coating method in which a free-fall curtain film is formed and collides with a traveling support is particularly preferable. This free-fall curtain coating method is preferable because uniform and good coated surface properties can be obtained without bubbles on the coated surface.

The coating amount is not particularly limited and may be determined according to the use of the heat-sensitive recording material, but when the heat-sensitive recording layer coating solution contains an electron donating dye as a color forming component, the amount of the dye applied is Usually, it is about 0.1-2.0 g / m < ² >, Preferably, it is 0.2-1.5 g / m < ² >. When the thermal recording layer coating liquid contains a diazo compound as a color forming component, the coating amount of the diazo compound is usually 0.05 to 5.0 g / m ² . The coating amount of the water-soluble resin contained in each layer coating solution is preferably from ^{0.4~5g / m 2, 0.8~1.6g / m} 2 is more preferable.

  The heat-sensitive recording material of the present invention is suitably used as monochromatic and multicolor recording paper for facsimiles and various printers.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this. “Part” and “%” described below represent “part by weight” and “% by weight”, respectively, unless otherwise specified.
[Reference Example 1]
7.0 g of ethylene-modified polyvinyl alcohol (ethylene modification degree 10 mol%, saponification degree 98.5 mol%, polymerization degree 550, hereinafter referred to as “PVA-1”) and stabilizer-1 (general formula (A) 80 mg of a compound in which R ⁰ and R ¹ are 2-ethylhexyl groups and M is sodium), 40 mg of stabilizer-2 (a compound in which R ² of general formula (B) is a 2-ethylhexyl group), and 92 of water After 0.0 g was added and sufficiently dispersed, the mixture was stirred at 95 ° C. for 2 hours to dissolve. Then, it cooled to room temperature, the density | concentration was adjusted, and 7.0% PVA-1 solution was prepared.

  2-anilino-3-methyl-6-N-ethyl-N-tetrahydrofurfurylaminofluorane (electron-donating colorless dye-1) and 4-β-p-methoxyphenoxyethoxysalicylic acid zinc (electron-accepting compound- 1), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane (hindered phenol-1), oxalic acid dibenzyl ester (sensitizer-1), Were separately mixed with 100 g of the 7% PVA-1 aqueous solution. Dispersion was performed with a ball mill all day and night to obtain dispersions having an average particle size of 1.5 μm or less. Further, 80 g of calcium carbonate (Pigment-1) was dispersed with a homogenizer together with 160 g of a sodium hexametaphosphate 0.5% solution to obtain a dispersion of Pigment-1.

Each dispersion prepared as described above was dispersed in 5 g of electron donating colorless dye-1, 10 g of electron accepting compound-1, 3 g of hindered phenol-1, and sensitizer-1. 10 g of dispersion, 5 g of pigment-1 dispersion, and 3 g of 21% zinc stearate emulsion were mixed to obtain a thermal recording layer coating solution.
This thermal recording layer coating solution was applied on high-quality paper weighing 50 g / m ³ using a Mayer bar so that the dry weight of the coating layer was 5 g / m ³ , dried at 50 ° C. for 1 minute, and thermal recording. A layer was prepared to obtain a thermal recording paper comprising a support and a thermal recording layer.

[Example 1]
In the preparation of the PVA solution of Reference Example 1, instead of Stabilizer-1 and Stabilizer-2, Stabilizer-3 (R ^{3 in the} general formula (C) is a nonylphenyl group, n = 3, and R ⁴ is A thermal recording paper was prepared in the same manner as in Reference Example 1 except that 120 mg of the compound (—CH ₂ ) ₄ OSO ₃ Na) was used.

[Example 2]
In the preparation of the PVA solution of Reference Example 1, instead of Stabilizer-1 and Stabilizer-2, Stabilizer-4 (R ^{3 in the} general formula (C) is a nonylphenyl group, n = 10, R ⁴ is A thermal recording paper was prepared in the same manner as in Reference Example 1 except that 120 mg of the compound (H) was used.
Example 3
In the preparation of the PVA solution of Reference Example 1, instead of Stabilizer-1 and Stabilizer-2, Stabilizer-5 (R ^{3 in the} general formula (C) is a nonylphenyl group, n = 15, R ⁴ A thermal recording paper was prepared in the same manner as in Reference Example 1 except that 120 mg of a compound in which H is H) was used.
Example 4
In the preparation of the PVA solution of Reference Example 1, instead of Stabilizer-1 and Stabilizer-2, Stabilizer-6 (R ^{3 in the} general formula (C) is a nonylphenyl group, n = 10, R ⁴ A thermal recording paper was prepared in the same manner as in Reference Example 1 except that 120 mg of a compound in which — (CH ₂ ) ₄ OSO ₃ Na was used.

[Comparative Example 1]
A thermal recording paper was prepared in the same manner as in Example 1 except that Stabilizer-3 was not used in the preparation of the PVA solution of Example 1.

<Evaluation>
(Evaluation of liquid life)
The PVA solutions of Examples 1 to 4 and Comparative Example 1 and the thermal recording layer coating solution were each allowed to stand for 3 days, and the presence or absence of precipitates and the increase in viscosity of the solutions were examined. Thereafter, the PVA solution was filtered using an 8 mmφ 1 micron filter, and the thermal recording layer coating solution was filtered using an 8 mmφ 30 micron filter, and the filterability of the PVA solution and the thermal recording layer coating solution was respectively determined. Examined. If the viscosity of the liquid does not increase even after being left, the liquid life of the liquid will be long. Moreover, the liquid life is longer as the filtration pressure does not increase during liquid filtration. Each liquid life was evaluated according to the following criteria.
A: No increase in viscosity was observed, filtration was not required, and the liquid life was extremely good.
B: Although the viscosity slightly increases, even when 200 ml is filtered, the filtration pressure does not increase and the liquid life is good.
C: Although the viscosity increased, 200 ml could be filtered and the liquid life was normal.
D: The viscosity was considerably increased, 200 ml could not be filtered, and the liquid life was slightly bad.
E: Crystalline precipitates were observed in the liquid, and filtration was not possible, and the liquid life was poor.

(Image quality evaluation)
The same image pattern with a density of 0.8 to 1.0 was printed on the thermal recording paper prepared in Examples 1 to 4 and Comparative Example 1 with a thermal head, and the images were visually observed to obtain a sheet shape. The degree of deterioration in image quality due to the occurrence of defects (unevenness with a major axis of 0.1 mm to 1.5 mm) was evaluated. The image quality of the obtained image was evaluated according to the following criteria. C or higher is a practical level.
A: There were no planar defects and the image quality was extremely good.
B: Although some surface defects are observed, the image quality is good.
C: Although some surface defects are observed, the image quality is normal.
D: Planar defects were observed, and the image quality was slightly poor.
E: Planar defects were considerably observed and the image quality was poor.

  The evaluation results of Examples 1 to 4 and Comparative Example 1 are shown in Table 1.

  From the results in Table 1, it is demonstrated that when the compound represented by the general formula (C) is contained as a stabilizer in the heat-sensitive recording layer, a high-quality image can be formed without generating planar defects in the image. It was done. It has also been demonstrated that the addition of these stabilizers to the coating solution improves the storage stability of the coating solution.

[Reference Example 2]
<Preparation of Coating Solution MC-4 for Thermosensitive Recording Layer>
(Preparation of capsule liquid (MC-1) encapsulating electron-donating colorless dye)
10.9 g of each of the compounds represented by the following structural formulas (I-1), (E-2), (E-3), (I-3), (E-5), and (E-6), 1.4 g, 2.1 g, 2.6 g, 0.4 g, and 0.4 g were dissolved by heating in 18 g of ethyl acetate. Then, after cooling to 40 ° C., 3.4 g of capsule wall agent (“Takenate D110N”, Takeda Pharmaceutical Company Limited), 10.2 g of capsule wall agent (“Takenate D127N”, Takeda Pharmaceutical Company Limited), and n-butanol 0.4g was added and it stirred at 40 degreeC for 40 minutes.

7% PVA-2 solution (PVA solution prepared by using “PVA217C” (PVA manufactured by Kuraray) instead of PVA-1 in the 7% PVA-1 solution prepared in Reference Example 1) After adding 46 g and 7 g of water to the mixed aqueous phase, an ace homogenizer (manufactured by Nippon Seiki Co., Ltd.) was used and emulsified and dispersed at 10,000 rpm for 5 minutes. After adding 66 g of water and 0.6 g of tetraethylenepentamine to the obtained emulsion, an encapsulation reaction was performed at 60 ° C. for 4 hours to obtain a capsule liquid MC-1 having an average particle size of 0.6 μm. Obtained.
The average particle diameter is a 50% volume average particle diameter measured using a laser diffraction particle size distribution analyzer (“LA700”, manufactured by Horiba, Ltd.). Also in the following, unless otherwise specified, the average particle diameter indicates the 50% volume average particle diameter measured in the same manner.

(Preparation of capsule liquid (MC-2) encapsulating electron-donating colorless dye)
10.5 g of each of the compounds represented by the following structural formulas (I-1), (E-2), (E-3), (I-3), (E-6), and (E-7), 1.4 g, 2.0 g, 4.2 g, 0.4 g, and 0.3 g were dissolved by heating in 20 g of ethyl acetate. Then, after cooling to 60 ° C., 3.7 g of capsule wall agent (“Takenate D110N”, Takeda Pharmaceutical Co., Ltd.) and 8.7 g of capsule wall agent (“Takenate D140N”, Takeda Pharmaceutical Co., Ltd.) are added and stirred. did.

  The obtained solution was added to an aqueous phase obtained by mixing 46 g of 7% PVA-2 solution prepared with MC-1 and 7 g of water, and then emulsified and dispersed at 10,000 rpm for 5 minutes using an ace homogenizer (manufactured by Nippon Seiki Co., Ltd.). Went. After adding 70 g of water and 0.8 g of tetraethylenepentamine to the obtained emulsion, an encapsulation reaction was performed at 60 ° C. for 3 hours to obtain a capsule liquid MC-2 having an average particle size of 0.6 μm. Obtained.

(Preparation of electron-accepting compound (developer) emulsion dispersion (MC-3))
The following structural formulas (F-1), (F-2), (F-3), (F-4), (F-5), (F-6), (F-7), and (F-8) ), 1.7 g, 5.5 g, 3.5 g, 3.4 g, 3.5 g, 4.6 g, 21.6 g, and 4.5 g, “TCP” (manufactured by Daihachi Chemical Co., Ltd.) Oil) 1.1 g, “DEM” (Daihachi Chemical Co., Ltd.) 0.6 g, and ethyl acetate 17.7 g were dissolved in a mixed solution.

  7% PVA-3 solution (PVA solution prepared by using “PVA205C” (PVA manufactured by Kuraray) instead of PVA-1 in the PVA-1 solution prepared in Reference Example 1) 46 7 g, 70.2 g of 7% PVA-2 solution used for the preparation of MC-1, 0.5 g of sodium dodecyl sulfonate, and 33.7 g of water were added to an aqueous phase, and then ACE homogenizer (Nippon Seiki The product was emulsified and dispersed at 10,000 rpm for 3 minutes to obtain an electron-accepting compound (developer) emulsion dispersion (MC-3) having an average particle size of 0.6 μm.

  5.4 g of the capsule liquid MC-1, 11.5 g of the capsule liquid MC-2, 70 g of the developer emulsified dispersion MC-3, and 26 g of water were mixed together to prepare a thermal recording layer coating liquid MC-4. Prepared.

<Preparation of coating solution for undercoat>
200 g of gelatin 5% aqueous solution (“# 810”, manufactured by Nitta Gelatin Co., Ltd.), 0.5 g of gelatin in which 5% of polymethyl methacrylate resin particles having a particle diameter of 2 μm are dispersed, and 1,2-benzothiazolin-3-one 3% aqueous solution 1.0 g and 10 g of a 2% aqueous solution of di (2-ethyl) hexyl sulfonate were mixed to obtain an undercoat layer coating solution.

<Preparation of thermal recording paper>
After coating SBR latex with a solid content weight of 0.3 g / m ² on one surface of polyethylene terephthalate with a thickness of 175 μm colored in blue, the coating solution for undercoat layer was applied to the solid content per side. A transparent support was obtained by coating so that the weight was 0.1 g / m ² . Next, on one surface of this transparent support (a surface different from the surface on which the undercoat layer was applied), the thermal recording layer coating solution MC-4 was applied so that the solid content weight was 14 g / m ^2. The dried thermal recording material of Reference Example 2 was produced.

Example 5
Instead of the stabilizer (stabilizer-1 and stabilizer-2) of the PVA solution used in Reference Example 2, stabilizer-4 (R ^{3 in the} general formula (C) is a nonylphenyl group, n = 10 and a compound in which R ⁴ is H) was used in the same manner as in Reference Example 2 to prepare a thermal recording paper.

[Reference Example 3]
A protective layer was provided on the thermal recording paper produced in Reference Example 2 using the protective layer coating solution prepared as described below, to produce a thermal recording paper having a two-layer structure comprising the thermal recording layer and the protective layer.
<Preparation of coating solution for protective layer>
27.1 g of water, 7% PVA-4 solution (in preparation of 7% PVA-1 solution used in Reference Example 1, instead of PVA-1, PVA 124C (Kuraray Co., Ltd. PVA) was used. Solution) 17.1 g, 0.3 g of dioctyl sulfosuccinate sodium salt solution 0.3 g, aluminum hydroxide dispersion (in the preparation of 7% PVA-1 solution of Reference Example 1, “PVA105” (Kuraray 15.0 g of a solution obtained by dispersing 28.6 g of a 7% PVA solution prepared using PVA) and 71.4 g of water in a ball mill) (15.0 g), and zinc stearate ( 0.5 g of “Hydrin Z” (manufactured by Chukyo Yushi Co., Ltd.) was mixed to obtain a protective layer coating solution.

Example 6
A protective layer was provided on the thermal recording paper produced in Example 5 using the coating liquid for protective layer, and a thermal recording paper having a two-layer structure comprising a thermal recording layer and a protective layer was produced.

Example 7
In the preparation of the protective layer coating solution of Reference Example 3, instead of the stabilizers (stabilizer-1 and stabilizer-2) contained in the 7% PVA-4 solution, stabilizer-4 (general A thermosensitive recording having a two-layer structure comprising a thermosensitive recording layer and a protective layer in the same manner as in Reference Example 3 except that R ^{3 in the} formula (C) is a nonylphenyl group, n = 10, and R ⁴ is H. Paper was made.
Example 8
In the preparation of the coating solution for protective layer of Example 6, stabilizer-4 (general) was used instead of stabilizers (stabilizer-1 and stabilizer-2) contained in the 7% PVA-4 solution. Except for using a compound in which R ^{3 in the} formula (C) is a nonylphenyl group, n = 10, and R ⁴ is H), a thermosensitive recording having a two-layer structure composed of a thermosensitive recording layer and a protective layer, as in Example 6. Paper was made.

[Comparative Example 2]
A thermosensitive recording paper having a single-layer structure was obtained in the same manner as in Example 5 except that a PVA solution containing no stabilizer was used as the PVA solution in the preparation of the thermal recording layer coating solution of Example 5.
[Comparative Example 3]
In the preparation of the thermal recording layer coating liquid and the protective layer coating liquid of Example 6, the thermal recording layer and the protective layer were protected in the same manner as in Example 6 except that a PVA solution containing no stabilizer was used as the PVA solution. A heat-sensitive recording paper having a two-layer structure consisting of layers was prepared.

  Examples 5 to 8, Comparative Example 2 and Comparative Example 3 were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

Claims (9)

(1) a step of preparing a water-soluble resin solution by stirring a water-soluble resin and a compound represented by the following general formula (C) while heating in water;
(2) adding a solid or liquid component to the water-soluble resin solution to prepare a coating solution;
(3) A method for producing a heat-sensitive recording material, comprising: applying the coating solution onto a support and drying to form a layer.

[In General Formula (C), R ³ represents an alkyl group having 8 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 6 to 20 carbon atoms. R ⁴ represents H or — (CH ₂ ) _m —OSO ₃ X. X represents an alkali metal, ammonium, or alkanol ammonium. n represents an integer of 3 to 20, and m represents an integer of 0 to 6. ]   2. The method for producing a heat-sensitive recording material according to claim 1, wherein in the step (1), the heating temperature is 80 ° C. or higher and 100 ° C. or lower. The method for producing a heat-sensitive recording material according to claim 1, wherein R ³ is an aryl group having 6 to 20 carbon atoms. The method for producing a heat-sensitive recording material according to claim 3, wherein R ⁴ is — (CH ₂ ) ₄ —OSO ₃ Na.   The method for producing a heat-sensitive recording material according to claim 4, wherein n is 3.   The method for producing a heat-sensitive recording material according to claim 4, wherein n is 10. The method for producing a heat-sensitive recording material according to claim 3, wherein R ⁴ is H.   The method for producing a thermosensitive recording material according to claim 7, wherein n is 10.   The method for producing a heat-sensitive recording material according to claim 7, wherein n is 15.