JPH02179788A - Recording material - Google Patents

Abstract

PURPOSE:To enhance the light fastness of a developed color image by using a specific fluorane derivative as an electron donating leuco dye. CONSTITUTION:A fluorane derivative represented by formula wherein a 6-position is substituted with an amino group which may be substituted, a 3-position is substituted with a halogen atom and a 2-position is substituted with an arylamino group having amino groups at least at the 2- and 6-positions thereof is used as an electron donating leuco dye. For example, the recording material thus constituted is formed as follows. That is, a microcapsule dispersion of 2-(2,6-diethylanilino)-3-chloro-6-diethylaminofluorane is prepared and this coating solution is applied to base paper by an air knife coater and dried to obtain an electron donating leuco dye-containing capsule sheet which is, in turn, superposed on an electron acceptive compound sheet. Load is applied to this recording material to develop a desired color.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a recording material, and more particularly to a recording material with improved light resistance of a colored image.

(Prior Art) Recording materials using electron-donating colorless dyes and electron-accepting compounds are already well known as pressure-sensitive paper, thermal paper, light-sensitive pressure-sensitive paper, electrically conductive thermal recording paper, thermal transfer paper, and the like. For example, British Patent No. 2140449, U.S. Patent No. 4480052, U.S. Patent No. 4436920, Japanese Patent Publication No. 60-23992, Japanese Unexamined Patent Publication No. 57
-179836, 60-123556, 60-12
I am familiar with 3557 etc.

As a recording material, in recent years (1) color density and color sensitivity (2)
) In particular, regarding (2), 2-(2,6-dimethylanilino)-3-methyl-6-sibutylaminofluorane has been extensively researched to improve properties such as fastness of color formers after irradiation with light. It is known that there is little red discoloration in the color image of
The effect was still insufficient.

The present inventors have discovered that specific compounds are effective in improving these properties.

(Object of the Invention) Accordingly, an object of the present invention is to provide a recording material that provides a colored image with good light resistance and also satisfies other requirements.

(Structure of the Invention) An object of the present invention is to provide a recording material that utilizes color development due to contact between an electron-donating colorless dye and an electron-accepting compound, even if the electron-donating colorless dye is substituted at the 6-position. This was achieved by a recording material characterized by using a fluoran derivative substituted with a good amino group, a halogen atom at the 3-position, and an arylamino group having an alkyl group at the 2- and 6-positions at the 2-position.

Preferred compounds of the present invention are shown in general formula (I).

In the above formula, R1 to R1 are hydrogen atoms, alkyl groups, aryl groups, R,, R, are alkyl groups, X is 710 gen atoms, and R6 is hydrogen atoms, alkyl groups, aryl groups, alkoxy groups, halogen atoms. , represents a nitro group or a substituted amine 7 group.

In addition, an alkyl group represents a saturated, unsaturated or cycloalkyl group, and these have a substituent such as an aryl group, an alkoxy group, an aryloxy group, an acyloxy group, a halogen atom, an acylamino group, an aminocarbonyl group, or a cyano group. You can leave it there.

In addition, the aryl group is a phenyl group, a naphthyl group, or a double Il! These represent an alkyl group, an alkoxy group, an aryloxy group, a halogen atom, a nitro group, a cyano group, a substituted carbamoyl group, a substituted sulfamoyl group, a substituted amino group, a substituted oxycarbonyl group, a substituted oxysulfonyl group, It may have a substituent such as an alkylthio group, an arylsulfonyl group, or a phenyl group.

It is preferable that R2 and R2 are not hydrogen atoms at the same time.

The R2-R1 substituent preferably has 18 or less carbon atoms, particularly 8 or less carbon atoms.

More specifically regarding R1 and R2, hydrogen atom, methyl group,
Ethyl group, n-propyl group, ISO-propyl group, n-
Butyl group, 15O-butyl group, n-amyl group, 1so-
amyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group, n-dodecyl group, n-
Octadecyl group, metquinpropyl group, ethoxypropyl group, fenoquinethyl group, cyclopentyl group, cyclohexyl group, tetrahydrofurfuryl group, phenyl group,
Examples include tolyl group, benzyl group, and phenethyl group.

R, , R, are bonded to each other to form a ring which may contain a 5- to 8-membered heteroatom, such as piperidine, morpholine, piperazine, hexamethyleneimine, pentamethyleneimine, caprolactam, isoquinoline, etc. You may.

R, R2N- refers to dimethylamino group, diethylamino group, dibutylamino group, N-ethyl-N-iso-
amylamino group, N-ethyl-N-iso-butylamino group, N-ethyl-N-hexylamino group, N-methyl-N-propylamino group, N-ethyl-N-tetrahydrofurfurylamino group, N- Ethyl-N-cyclopentylamino group, pentamethyleneimino group, N-ethyl-N
-methoxypropylamino group, N-ethyl-N-ethoxypropylamino group, N-ethyl-N-)lylamine 7 group, etc. are preferred.

Among the substituents represented by R1, hydrogen atom, carbon atom number 1
to 18 alkyl groups and aryl groups having 6 to 12 carbon atoms are preferred.

R1 is particularly preferably a hydrogen atom or a methyl group.

Among the substituents represented by R4 and R5, an alkyl group having 1 to 5 carbon atoms is preferred.

Rs is particularly preferably a methyl group, an ethyl group, or a propyl group.

Among the substituents represented by X, chlorine atom, fluorine atom, and bromine atom are preferred.

Among the substituents represented by R6, hydrogen atom, carbon atom number 1
to 12 alkyl groups, aryl groups having 6 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms, chlorine atoms, bromine atoms, nitro groups, 7 mono- or dialkyl groups having 1 to 12 carbon atoms, carbon An acylamino group having 1 to 12 atoms is preferred.

Next, specific examples of the colorless dye of the present invention will be shown, but the present invention is not limited thereto.

(1) 2-(2,6-dimethylanilino)-3-
Chloro-6-dinithylaminofluorane (2) 2- (2,6-dimethylanilino)-3-
Chloro-6-sibutylaminofluorane (3) 2- (2,6-dinitylanilino)-3-
Rilowa-6-diethylaminofluorane (4) 2- (2,6-dimethylanilino)-3-
ri o o -5-N-tetrahydrofurfuryl-N ethylaminofluorane (5) 2- (2,6-dimethylanilino)-3-
Chloro-6-N-iso-amyl-N-ethylaminofluorane (6) 2- (2,6-dimethylanilino)-3-
Chloro-6-N-)dyl-N-dithylaminofluorane (7) 2-(2,4,6-)limethylanilino)
-3-chloro-6-dinithylaminofluorane (8)
2-(2,6-dimethylanilino)-3-bromo-
6-Dinithylaminofluorane (9) 2- (2,6-dimethylanilino)-3-
Chloro-6-N-ethquinpropyl-N-ethylaminofluorane α, [)2-(2,6-dimethylanili/)-3-fluoro-6-ethylaminofluorane These colorless dyes have already been Well-known triphenylmethane phthalide compounds, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, leucoolamine compounds, rhodamine lactam compounds, triphenylmethane compounds, triazene compounds, spiropyran It is also possible to assemble recording materials by using it in combination with various compounds such as fluorene-based compounds and fluorene-based compounds.

In this case, it is preferable to use the above-mentioned colorless dye in an amount of 40% or more from the viewpoint of improving properties.

Regarding these, for example, specific examples of phthalides are U.S. Patent Reissue No. 23,024 and U.S. Patent Specification No. 3.
, 491,111, 3,491.112, 3,491.116, and 3.509,174, and specific examples of fluorans are U.S. Patent Specification No. 3.624.
, No. 107, No. 3,627,787, No. 3,64
No. 1,011, No. 3,462.828, No. 3.6
No. 81.390, No. 3,920.510, No. 13.
No. 959,571, specific examples of spiropyrans are given in U.S. Patent No. 3.9.71,808, and pyridine and pyrazine compounds are given in U.S. Patent No. 3,775,42.
No. 4, No. 3,853゜869, No. 4,246.3
No. 18, specific examples of fluorene compounds are given in Japanese Patent Application No. 61-2
No. 40989, etc.

Examples of electron-accepting compounds that impart color upon contact with colorless dyes include common compounds such as phenol derivatives, salicylic acid derivatives, metal salts of aromatic carboxylic acids, acid clay, bentonite, novolac resins, metal-treated novolac resins, and metal complexes. are used, and these may be used in combination. Examples of these are Tokuko No. 9309, No. 40-9309, and Tokuko No. 4
5-14039, JP 52-140483, JP 48-51510, JP 57-210886,
JP-A-58-87089, JP-A-59-11286, JP-A-60-176795, JP-A-61-9598
No. 8, U.S. Patent Application No. 3゜767.449, U.S. Patent No. 4
, No. 219,219, No. 4,269,893, No. 4.374.671, No. 4.687,869, etc. In particular, combinations with salicylic acid derivatives and phenol derivatives are preferred.

When these are applied to recording materials, they are used in the form of fine dispersions or fine droplets, or in the form of films.

Furthermore, in this case, various additives well known in the fields of recording materials and polymer resins, such as pigments, waxes, antistatic agents, ultraviolet absorbers, antifoaming agents, conductive agents, and fluorescent agents, are used. Additives such as dyes and surfactants are used.

For use with pressure sensitive paper, U.S. Patent No. 2,505.47
No. 0, No. 2,505,471, No. 2505.489, No. 2,548,366, No. 2,712,507,
No. 2,730,456, No. 2,730.457, No. 3,103,404, No. 3,418,250, No. 4
It may take a variety of forms, as described in prior patents such as No. 010,038. It most commonly consists of at least one pair of sheets containing separately an electron-donating colorless dye and an electron-accepting compound.

A method of manufacturing capsules is described in U.S. Pat. No. 2.800.
457, a method using coacervation of a hydrophilic colloid sol described in British Patent Nos. 2,800,458, British Patent No. 867.797, British Patent No. 950,443, British Patent No. 98
Examples include the interfacial polymerization method described in US Pat. No. 9.264 and US Pat. No. 1.091.076, and the method described in US Pat.

The capsule wall material is preferably a synthetic resin-based wall material, for example, a polyurethane and/or polyurea-based material, or a melamine resin-based material.

In general, electron-donating colorless dyes are used alone or in combination as solvents (alkylated naphthalene, alkylated diphenyl, alkylated diphenylmethane, alkylated terphenyl, alkylated terphenyl, etc.).
Synthetic oils such as chlorinated paraffin; vegetable oils such as cotton oil and castor oil; animal oils; mineral oils, or mixtures thereof, etc.) and contain them in microcapsules to produce paper, high-quality paper, plastic sheets, and resin coats. A coloring agent sheet is obtained by applying it to ted paper, etc.

In addition to the electron-donating colorless dye, ultraviolet absorbers, antioxidants, and the like may be added as additives to the microcapsules. In particular, from the viewpoint of improving the stability of the electron-donating colorless dye in the capsule before use and the coloring of the capsule, benzo) IJ azole-based external radiation absorbers, hindered amino-based antioxidants, hindered phenol-based antioxidants It is preferable to add agents, aniline antioxidants, quinoline antioxidants, and the like.

In addition, an electron-accepting compound and optionally additives may be dispersed in a binder such as styrene-butadiene latex or polyvinyl alcohol, and used together with the pigments described below to produce paper, plastic sheets, resin-coated paper, etc. A developer sheet is obtained by coating the support.

The amounts of the electron-donating colorless dye and the electron-accepting compound to be used depend on the desired coating thickness, the form of the pressure-sensitive recording paper, the capsule manufacturing method, and other conditions, and may be appropriately selected depending on the conditions. It is easy for one skilled in the art to determine this amount to use.

When used for thermal paper, JP-A-62-144゜989
No. 62-244,883, etc. Specifically, the electron-donating colorless dye and the electron-accepting compound are 1Oμ or less in the dispersion medium.
It is preferably used after being pulverized and dispersed to a particle size of 3 μm or less. As the dispersion medium, an aqueous polymer solution having a concentration of about 0.5 to 10% is generally used, and dispersion is carried out using a ball mill, sand mill, horizontal sand mill, attritor, colloidal mill, or the like.

The ratio of the electron-donating colorless dye to the electron-accepting compound used is preferably between 1=10 and 1:1 by weight, and particularly preferably between 1:5 and 2:3. At that time, it is preferable to use a thermofusible substance in combination. These are used in finely dispersed form at the same time as the electron-donating colorless dye or simultaneously with the electron-accepting compound. These are added at a weight ratio of 20% or more and 300% or less, particularly preferably 40% or more and 150% or less, based on the electron-accepting compound.

Additives may be added to the thus obtained coating liquid as necessary to meet various requirements. Examples of additives include dispersing oil-absorbing substances such as inorganic pigments and polyurea fillers in the binder in order to prevent the recording head from becoming dirty during recording, and also to improve releasability from the head. For this reason, fatty acids, metal soaps, etc. are added. Therefore, in addition to electron-donating colorless dyes and electron-accepting compounds that directly contribute to color development, thermofusible substances, pigments, waxes, antistatic agents, ultraviolet absorbers,
Additives such as antifoaming agents, conductive agents, fluorescent dyes, and surfactants are coated onto the support to form the recording material.

Furthermore, a protective layer may be provided on the surface of the heat-sensitive recording layer, if necessary. Two or more protective layers may be laminated as necessary. Further, a coating liquid similar to that of a protective layer may be applied to the back surface in order to correct the curl balance of the support or to improve chemical resistance from the back surface. An adhesive may be applied to the back side and a release paper may be further added to form a label.

Usually, the electron-donating colorless dye and the electron-accepting compound are dispersed in a binder and applied. Water-soluble binders are generally used, such as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, epichlorohydrin-modified polyamide, and ethylene-
Examples include maleic anhydride copolymer, styrene-maleic anhydride copolymer, inbutylene-maleic anhydride copolymer, polyacrylic acid, polyacrylic acid amide, methylol-modified polyacrylamide, starch derivatives, casein, gelatin, etc. . Further, for the purpose of imparting water resistance to these binders, a water resistance agent may be added, or an emulsion of a hydrophobic polymer, specifically, styrene-butadiene rubber latex, acrylic resin emulsion, etc. may be added. The coating solution is applied onto base paper, wood-free paper, synthetic paper, plastic paper, sheet, resin-coated paper, or neutral paper.

Examples of thermofusible substances are disclosed in JP-A-58-57989 and JP-A-58-87094. Examples of such compounds include 2-benzyloxynaphthalene, 4
-benzylbiphenyl, di-m-)lyloxyethane,
1,2-diphenoxyethane, 1,4-diphenoxybutane, bis-[β-(p-methoxyphenoxy)ethyl ether, 1-phenoxy-2-p-ethylphenoxyethane, 1-p-methoxyphenoxy- 2-phenoxypropane, 1-phenoxy-2-p-methoxyphenoxypropane, 1.2-bis(p-methoxyphenoxy)propane, 1.3-bis(p-methoxyphenoxy)
Propane, 1-p-methoxyphenoxy-2-o-chlorophenoxyethane, 4-(p-methoxybenzylthio)anisole, 1-phenoxy-2-p-methoxyphenylthioethane, l,2-bis(p-methoxy Ether compounds such as phenylthio)ethane, 1-p-methylphenoxy-2-p-methoxyphenylthioethane, stearic acid amide, methylene bisstearamide, stearic acid anilide, behenic acid amide, stearic acid anilide, stearyl urea, etc. can be given.

Pigments include kaolin, calcined kaolin, talc, diatomaceous earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, zinc oxide, lithopone, amorphous silica, colloidal silica, calcined stone wax, silica, magnesium carbonate, titanium oxide, alumina. , barium carbonate, barium sulfate, mica, microballoons, urea-formalin fillers, polyester particles, cellulose fillers, etc. are used.

Examples of metal soaps include polyvalent metal salts of higher fatty acids, such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate.

Examples of waxes include paraffin wax, carboxy-modified paraffin wax, carnauba wax, microcrystalline wax, polyethylene wax, polystyrene wax, higher fatty acid esters, amides, and the like.

As the hindered phenol compound, a phenol derivative in which at least one of the 2nd and 6th positions is substituted with a branched alkyl group is preferred. For example, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1°1.3-)lis(2-ethyl-4-
Hydroxy-5-t-butylphenyl)butane, l, l
, 3-tris(3,5-di-t-butyl-4-hydroxyphenyl)butane, 1,1.3-)lis(2-methyl-4-hydroxy-5-t-butylphenyl)propane, 4. 4-Butylidenebis(6-phthyl-3-methylphenol, 4,4-thiobis(3-methyl-6-t)
-butylphenol), 2,2-methylenebis(6-t
-butyl-4-methylphenol), 2,2-methylenebis(6-t-butyl-4-ethylphenol), octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 1 ,3,5-trimethyl-2,4,6-tris(3,5-dit-)f-4-
hydroxybenzyl)benzene, tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propinate comethane, 2,2,6,6-tetramethyl-4-piperidinyl sebacate, etc. can be given.

The amount of the hindered phenol compound used is preferably 1 to 200% by weight, and more preferably 5 to IOQ% by weight, based on the electron accepting compound.

As ultraviolet absorbers, cinnamic acid derivatives, benzophenone derivatives, benzotriazolylphenol derivatives, etc.
For example, butyl α-cyano-β-phenylcinnamate, O
-benzotriazolylphenol, O-benzotriazolyl-p-chlorophenol, 0-benzotriazolyl-2,4-di-t-butylphenol, O-benzotriazolyl-2,4-di-t -Octylphenol etc.

Water-resistant agents include water-soluble initial condensates such as N-methylol urea, N-methylol melamine, and urea-formalin;
Blend heat treatment of dialdehyde compounds such as glyoxal and glutaraldehyde, inorganic crosslinking agents such as boric acid and sensa, polyacrylic acid, methyl vinyl ether-maleic acid copolymer, inbutylene-maleic anhydride copolymer, etc. can give.

Materials used for the protective layer include polyvinyl alcohol,
Carboxy-modified polyvinyl alcohol, vinyl acetate-acrylamide copolymer, silicon-modified polyvinyl alcohol, starch, modified starch, methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, gelatin, gum arabic, casein, styrene-maleic acid copolymer hydrolyzate, Water-soluble polymers such as styrene-maleic acid copolymer half ester hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyacrylamide derivatives, polyvinyl vicritone, polystyrene sodium sulfonate, sodium alginate, and styrene-
Water-insoluble polymers such as butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion are used.

In addition, pigments, metal soaps, waxes, waterproofing agents, etc. may be added to the protective layer for the purpose of improving matching properties with the thermal head.

Further, when coating the protective layer on the thermosensitive coloring layer, a surfactant may be added in order to obtain a uniform protective layer. As the surfactant, a sulfosuccinic acid-based alkali metal salt, a fluorine-containing surfactant, etc. are used. Specifically, G (
Sodium salts or ammonium salts such as n-hexyl)sulfosuccinic acid and di(2-ethylhexyl)sulfosuccinic acid are preferred, but anionic surfactants are effective.

Electric thermal paper is manufactured by the method described in, for example, JP-A-49-11344 and JP-A-5 (1-48930).Generally, a conductive substance, an electron-donating colorless dye, and an electron-accepting compound are combined with a binder. A dispersed coating liquid is applied to a support such as paper, or a conductive material is applied to the support to form a conductive layer, and then an electron-donating colorless dye, an electron-accepting compound, and a binder are dispersed thereon. The electrically conductive thermal paper is manufactured by applying a liquid. Note that the above-mentioned thermofusible substance can also be used in combination to improve the sensitivity.

The photosensitive pressure sensitive paper is manufactured by the method described in, for example, Japanese Patent Application Laid-open No. 179836/1983. In general, photopolymerization initiators such as silver bromide, silver bromide, silver behenate, Michler's ketone, benzoin derivatives, benzophenone derivatives, etc. and crosslinking agents such as polyallyl compounds, poly(meth)acrylates, poly(meth)acrylamides, etc. is encapsulated in a synthetic resin capsule such as polyethyl urethane or polyurea together with an electron-donating colorless dye and, if necessary, a solvent. After being imagewise exposed, it is colored by contacting with an electron-accepting compound using an electron-donating colorless dye.

The electron-donating colorless dye according to the present invention can be easily obtained, for example, by reacting a compound of general formula (I[) with a corresponding substituted phenyl halide.

Acid palladium and the like are preferred.

Bromine or iodine is particularly preferred as the aforementioned halide.

Alternatively, the colorless dye of the present invention can be prepared by combining a compound of general formula (III) and a compound of general formula (IV) (R represents a hydrogen atom or a lower alkyl group) with an acid catalyst such as concentrated sulfuric acid, fuming sulfuric acid, or phosphoric acid. It can also be easily obtained by condensation using

The reaction is carried out at a temperature of 60° C. to 270° C. for about 30 minutes to 24 hours in the presence of a base and a catalyst. In this case, phase transfer catalysts may be used.

As the base, oxides, hydroxides, and carbonates of Na, Mg are preferable.

As a catalyst, copper, copper halide, copper oxide, vinegar synthesis example 2- (2,6-dimethylanilino)-3-chloro-6
-Dinithylaminofluorane In a three-necked flask equipped with a stirrer, 2-amino-3
-Chloro-6-dinithylaminofluorane Qmmo
1,2,6-dimethyliodobenze 711 mmol,
1 mmol of copper, 12 mmol of potassium carbonate, 1 mm of 18-crown-6-x-fle.

1. Weigh out 5 ml of o-dichlorobenzene,
Stir at 50 for 6 hours. The reaction mixture is filtered, water is poured into the filtrate, and the mixture is further extracted with ethyl acetate and purified with a silica gel column to obtain the desired product with a melting point of 167-9°C.

(Examples of the Invention) Examples are shown below, but the present invention is not limited thereto. % represents weight % unless otherwise specified.

(Examples 1 to 4) (1) Preparation of capsule sheet containing electron-donating colorless dye 5 parts of a partial sodium salt of polyvinylbenzenesulfonic acid (manufactured by Nanyonal Starch Co., Ltd., VER3A, Tl2O3) was dissolved in 95 parts of hot water. Cool afterwards. A sodium hydroxide aqueous solution was added to this to adjust the pH to 4.0. 100 parts of diisopropylnaphthalene in which 3.5% of the electron-donating colorless dye shown in the first method was dissolved was emulsified and dispersed in 100 parts of a 5% aqueous solution of IJum salt (100 parts of the polyvinylbenzenesulfonic acid) to a diameter of 4.0 μm. An emulsion with a particle size of . Separately, 11 parts of a 61.37% by weight formaldehyde aqueous solution of melamine and 30 parts of water were heated and stirred at 60°C, and after 30 minutes, a transparent aqueous solution of melamine formaldehyde prepolymer was obtained.

This aqueous solution was mixed with the above emulsion. While stirring, the pH was adjusted to 6.0 with a 2M phosphoric acid solution, the temperature of the solution was raised to 65°C, and stirring was continued for 6 hours. This capsule liquid is cooled to room temperature and hydroxylated with IJum aqueous solution. l], adjusted to 0.

To this dispersion, 200 parts of a 10% by weight polyvinyl alcohol aqueous solution and 50 parts of starch particles were added and water was added to prepare a solution of the microcapsule fraction with a solid content concentration of 20%.

This coating liquid was coated on a 50 g/m2 base paper using an air knife coater so that the solid content was 5 g/m2, and dried to obtain a capsule sheet containing an electron-donating colorless dye.

(2) Preparation of electron-accepting compound sheet 3.5-bis-α-methylbenzylsalicylic acid zinc salt 1
0 part was added to 20 parts of 1-isopropylphenyl-2-phenylethane and dissolved. This was mixed with 50 parts of a 2% polyvinyl alcohol aqueous solution and 0.1 part of a 10% dodecylbenzenesulfonic acid trienol amino salt aqueous solution and emulsified so that the average particle size was 3 μm.

Next, a dispersion consisting of 80 parts of calcium carbonate, 20 parts of zinc oxide, 1 part of sodium hexametaphosphate, and 200 parts of water was mixed with the above emulsion and added as a binder to 1001 m of a 10% PVA aqueous solution and carboxy-modified SB.
10 parts of R latex (as solid content) was added and water was added so that the solid content concentration was 20% to obtain a coating liquid (A).

Next, 10 parts of the electron-accepting compound, 20 parts of Jilton clay
A dispersion liquid consisting of 200 parts of water, 60 parts of calcium carbonate, 20 parts of zinc oxide, 1 part of sodium hexametaphosphate, and 200 parts of water was dispersed using a sand grinder so that the average particle size was 3 μm.

Add 116 parts of 10% PVA aqueous solution and 10% PVA to this dispersion.
100 parts of an aqueous solution and 10 parts of carboxy-modified SBR latex (as solid content) were added, and water was added so that the solid content concentration was 20% to obtain a coating liquid (B).

Coating liquid (A) and coating liquid (B) were mixed 1:1 in terms of electron-accepting compound, and applied to 50 g/m2 base paper.
The mixture was coated using an air knife coater so that a solid content of 100% was coated, and dried to obtain an electron-accepting compound sheet.

The surface of the microcapsule sheet containing an electron-donating colorless dye is
When the electron-accepting compound sheets were stacked and a load of 600 kg/m' was applied, each sheet quickly developed a dark line black color. The color image obtained is
(FAL 2SAX HC type)" (manufactured by Suga Test Instruments) for 8 hours, no red change was observed.

The colorless dyes used are as follows.

Example 1 Compound Example 2 of Specific Example (1) Compound Example 3 of Specific Example (2) Compound Example 4 of Specific Example (5) Compound of Specific Example (9) and 2-anilino-3-methyl-6
- 1/1 (weight ratio) mixture of dinithylaminofluorane (Example 5) Compound of Example (1), bisphenol A which is an electron accepting compound, 1,2-bis(4) which is a thermofusible substance -Methoxyphenoxy)propane, 20 g of each was dispersed with 100 g of a 5% polyvinyl alcohol (Kuraray PVA 105) aqueous solution in a ball mill overnight to give a volume average particle diameter of 1.5 μm or less to obtain each dispersion. In addition, 80g of calcium carbonate was added to 0.5g of sodium hexametaphosphate.
% solution using a homogenizer to obtain a pigment dispersion.

Each of the dispersions prepared as described above was mixed in a ratio of 5 g of an electron-donating colorless dye dispersion, 10 g of an electron-accepting compound dispersion, 10 g of a thermofusible substance dispersion, and 15 g of a pigment dispersion,
Further, 3 g of a 21% zinc stearate emulsion was added to obtain a heat-sensitive coating liquid.

This coating liquid was applied to high-quality paper using Coating-E so that the dry weight of the coating layer was 5 g/m'.
After drying at 0° C. for 1 minute, a super calender was applied to obtain thermal recording paper.

The obtained thermal recording paper was free from fog during raw storage and had excellent stability over time.

Thermal recording paper was heated using a thermal head manufactured by Kyocera Corporation (KLT-
216-8MPD1) and 100kg/just before the head.
Printing was carried out with a pulse width of 1.0 using a thermal printing experimental device with a pressure roll of ci under conditions of a head voltage of 24 V and a pulse cycle of 1 Qms, and the print density was measured using a Macbeth reflection densitometer RD- Measured at 918. The concentration was 1.3. The color image obtained is “
Even after 8 hours of light irradiation using a xenon fade meter (model FAL-25AX-HC) (manufactured by Suga Test Instruments), no red change was observed.

(Comparative Example 1.2) 2-anilino-3-chloro-6-dinithylaminofluoran [Example 1: l, 2-(2,6-
A colored image was obtained in the same manner as in Example 1 using Comparative Example 2 using (dimethylanilino)-3-methyl-6-sibutylaminofluorane. When this colored image was irradiated with light for 4 hours using a ``xenon fade meter (model FAL-25AX-HC)'' (Suga Test Instruments), a red change was observed.

Claims (1)

[Claims] In a recording material that utilizes color development due to contact between an electron-donating colorless dye and an electron-accepting compound, the electron-donating colorless dye includes an optionally substituted amino group at the 6-position, a halogen atom at the 3-position, and a halogen atom at the 3-position. A recording material characterized by using a fluoran derivative substituted with an arylamino group having an alkyl group at at least the 2nd and 6th positions.