JPH04187484A - Recording material - Google Patents

Abstract

PURPOSE:To improve color forming density, resistance to light, and the like to stabilize color-forming properties by a method wherein in a recording material using a color forming reaction caused by the contact of an electron donative colorless dye and an electron accepting compound, a specific compound is used as the electron donative colorless dye. CONSTITUTION:In a recording material using a color forming reaction caused by the contact of an electron donative colorless dye and an electron accepting compound, a triphenyl methaphthalide derivative having alkyl group substituted by a group having anti-oxidizing properties is used as the electron donative colorless dye. As the group having anti-oxidizing properties, a hindered phenol derivative or a diaryl amine derivarive is preferably used. In this manner, an obtained color forming part can be enhanced in density and superior in light resistance.

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 stability of color-developing areas.

(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. Pat.
For details, see No. 60-123557.

As a recording material, in recent years (1) color density and color sensitivity (2)
) Research is being carried out to improve the properties before use and the fastness of the colored part.

Among these, regarding the color recording materials for fruits and vegetables, especially (2)
There is a strong demand for

For example, the blue coloring agent 3.3-his(p-tsumethylaminophenyl)-6-tumethylaminophthalide (i.e., crystal violet lactone) develops a deep blue color quickly, or the light resistance of the coloring part is poor. It is extremely poor.

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

(Object of the Invention) Accordingly, an object of the present invention is to provide a recording material using a material that has good stability of the coloring part and satisfies other requirements.

(Structure of the Invention) An object of the present invention is to provide a recording material that utilizes color development through contact between an electron-donating colorless dye and an electron-accepting compound, in which the electron-donating colorless dye is substituted with a group having antioxidant ability. This was achieved by a recording material characterized by using a triphenylmethane phthalide derivative having an alkyl group.

Examples of the above-mentioned group having antioxidant ability include hindered phenol derivatives, diarylamine derivatives, quinoline derivatives, hindered amine derivatives, and particularly preferred are hindered phenol derivatives and diarylamine derivatives.

As the hindered phenol derivative and diarylamine derivative, those represented by the following general formulas (I) and (II) are preferred.

j K3nop Among the substituents represented by R+ and 'R2 in the above formula, hydrogen atoms, alkyl groups, aryl groups, and haloken atoms are preferred, and alkyl groups are particularly preferred.

In addition, an alkyl group and an aryl group further include an alkyl group, an alkoxy group, an aryl 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, and a substituted oxy group. It may have a substituent such as a sulfonyl group, an alkylthio group, or an arylsulfonyl group.

R1 and R2 are a hydrogen atom, a methyl group, an ethyl group,
n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, n-amyl group, isoamyl group, n-hexyl group, n-hebutyl group, n-octyl group, 2-ethylhexyl group, Cyclopentyl group, cyclohexyl group, phenyl group, tolyl group, chlorophenyl group,
Examples include methoxyphenyl group, hensyl group, phenethyl group, methyl hensyl group, chlorohensyl group, methoxypencyl group, chlorine atom, bromine atom, and fluorine atom.

Among the substituents represented by R3, hydrogen atoms, alkyl groups,
Preferred are an aryl group, an alkoxy group, an aryloxy group, a cyano group, a nitro group, a substituted amino group, a hydroxy group, a halogen atom, an alkoxycarbonyl group, an aryloxycarbonyl group, and an acyloxy group.

R3 is a hydrogen atom, methyl group, ethyl group, propyl group, butyl group, octyl group, phenyl group, tolyl group, benzyl group, phenethyl group, methoxy group, ethoxy group, propoxy group, butoxy group, octyloxy group, benzyl Oxy group, phenoxyethoxy group, phenoxy group, chlorine atom, bromine atom, fluorine atom, nitro group, cyano group, dimethylamino group, diethylamino group, dipropylamino group, dibutylamino group, cypentylamino group, dihekynylamino group , dioctylamino group, diphenylamino group,
ditolylamino group, dibenzylamino group, N-methyl-
N-ethylamino group, N-methyl-N-butylamino group, N-ethyl-N-butylamino group, N-ethyl-N-
β-methoxyethylamino group, N~ethyl-N-β-ethoxyethylamino group, N-ethyl-N-β-phenoxoethylamino group, N-methyl-N-β-cyanoethylamino group, N-methyl- N-β-chloroethylamino group, N-ethyl-N-cyclohexylamino group, N-ethyl-N-pentylamino group, N-ethyl-N-tetrahydrofurfurylamino group, N-ethyl-N-)lylamino group group, N-ethyl-N-methoxyphenylamino group, N
-ethyl-N-benzylamino group, N-ethyl-N-chlorobenzylamino group, pyrrolidino group, piperidino group,
Morpholino group, piperazino group, acetylamino group, acetyloxy group, methoxycarbonyl group is anilino group, 4
-methylphenylamino group, 4-chlorophenylamino group, 4-methoxyphenylamino group, 3-methylphenylamino group, and methylamino group.

p represents an integer of l or 2;

Among the substituents represented by R6 in the above formula, a hydrogen atom, an alkyl group, and an aryl group are preferred.

As R, hydrogen atom, methyl group, ethyl group, propyl group, butyl group, octyl group, phenyl group, tolyl group,
Chlorophenyl group, methoxyphenyl group, benzyl group,
phenethyl group, methylbenzyl group, chlorobenzyl group,
A methoxybenzyl group is mentioned, a hydrogen atom is particularly preferred, and -NR4- is preferably a para-substituted group.

Among the substituents represented by R1 to R1° in the above formula, the above-mentioned R
A group similar to 2 is preferable, and q is preferably an integer from I to 4.

Further, the alkylene moiety of the alkyl group substituted with a group having antioxidant ability preferably has 1 to 20 carbon atoms, and the alkylene moiety is preferably one represented by the following general formula (I).

-(Lo)a-(Ll)i(LX)c-(R3), 1-
(R4)e-(R5), -(R6), (I) In the above formula, ,R2,L,,L, is -〇-1-NR,-1-N
R,C0-1-CONR,-1-NR,5o2-1-8
O2NR,-1-COO-1-OCO-2-NR,C0
NR, -1-0CONR, -1-NR,COO-1-C
HOH-1-8-1-SO-1S O2-1-CO-(
R represents a hydrogen atom, an alkyl group, an aryl group, or an acyl group); L, , R2, and Ls represent alkylene, aralkylene, or alkenylene; and a-g represent an integer of 0 or I.

L+, Li, and Ls are preferably alkylene, aralkylene, or alkenylene having 1 to 20 carbon atoms.

L,,L,,L, is -(CH,)-,-(CH
2) 2-1-(CL)□-1-(C)1. ), -1-(
CH2)a-1-(CH2)$-1-(CH2)7-1
to (CH2)s-5-(CI(2) 5-1-(CL)
1. -1. -(CH2CHCH2)-1, -CH2-C
Examples include H=CH-CH2-.

Ra is preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, or a heterocyclic group;
Examples include a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, an octyl group, a phenyl group, a tolyl group, a chlorophenyl group-methoxyphenyl group, and a benzyl group.

Particularly preferred compounds of the present invention are shown in the following general formula (■).

In the above formula, RII to R1, represent a hydrogen atom, an alkyl group, or an aryl group, and RI7 to R1, represent a group similar to the above-mentioned R3.
-t preferably represents an integer from 1 to 4.

However, at least one of R11 to R16 represents an alkyl group substituted with a group having antioxidant ability.

Specifically, R11 to R16 are preferably a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or an aryl group having 6 to 12 carbon atoms, and further R11 and RI2, R13 and R34, R
IS and RIG are bonded to each other to form a ring which may contain a 5- to 8-membered heteroatom including the nitrogen atom to which they are bonded, such as pyrrolidine, piperidine, morpholine, thiomorpholine, piperazine, caprolactam. N RIIRr t, N RIffR+4, N which may form a ring, and may further include a benzene ring to form an indoline or julolidine ring
R, s R, * are dimethylamino group, diethylamino group, dipropylamino group, dibutylamino group, diethylamino group, diethylamino group, dioctylamino group, diphenylamino group, ditolylamino group, dibenzylamino group, N-methyl- N-ethylamino group, N-methyl-N-butylamino group, N-ethyl-N-butylamino group, N-ethyl-N-β-methoxyethylamino group, N-ethyl-N-β-ethoxyethylamino group group, N-
Ethyl-N-β-phenoxyethyl ryomino group, N-methyl-N-β-cyanoethylamino group, N-methyl-N-
β-chloroethylamino group, N-ethyl-N-cyclohexylamino group, N-ethyl-N-pentylamino group,
N-ethyl-N-tetrahydrofurfurylamino group, N
-Ethyl-N-tolylamino group, N-ethyl-N-methoxyphenylamino group, N-ethyl-N-benzylamino group, N-ethyl-N-chlorobenzylamino group, pyrrolidino group, piperidino group, morpholino group, piperazino group The basics are given.

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

LL'i3'cH3 013'-O(3 In addition, these colorless dyes include well-known triphenylmethane phthalide compounds, fluoran compounds,
Recording materials can be produced in combination with various compounds such as phenothiazine compounds, indolylphthalide compounds, leucoauramine compounds, rhodamine lactam compounds, triphenylmethane compounds, triazene compounds, spiropyran compounds, and fluorene compounds. It can also be assembled.

In this case, it is preferable to use the above-mentioned colorless dye in an amount of 30% or more from the viewpoint of improving properties.

Regarding these, for example, specific examples of phthalides are U.S. Reissue Patent No. 23.024 and U.S. Patent No. 3゜491.111.
No. 3,491,112, No. 3,491,116 and No. 3,509,174, and specific examples of fluorans are U.S. Pat.
No. 7, No. 3゜641.011, No. 3,462,828
No. 3,681,390, No. 3,920,510, No. 3,959,571, specific examples of subirodipyrans are U.S. Pat. No. 3,971,808, and pyridine and pyrazine compounds are U.S. Pat. Specific examples of fluorene compounds are described in Japanese Patent Nos. 3,775,424, 3,853,869, and 4,246,318, and Japanese Patent Application No. 61-240989.

Electron-accepting metal compounds that impart color upon contact with colorless dyes include common compounds such as phenol derivatives, salicylic acid derivatives, metal salts of aromatic carbonic acids, acid clay, bentonite, novolac resins, metal-treated novolac resins, and metal complexes. , benzoquinone derivatives, etc. are used, and these may be used in combination. These examples are
No. 9309, Japanese Patent Publication No. 14039, 1973, Japanese Patent Publication No. 1972-
No. 140483, Japanese Patent Application Publication No. 1973-51510, Japanese Patent Application Publication No. 1973
7-210886, JP 58-87089, JP 59-11286, JP 60-176795,
JP 61-95988, U.S. Patent No. 3,767.44
No. 9, No. 4,219゜219, No. 4,269.893
No. 4,374.671, No. 4,687,869, European Patent No. 55,847, etc. Particularly preferred are combinations with salicylic acid derivatives, phenol derivatives, and metal complexes. 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.

In addition, 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 also added. Additives such as dyes and surfactants are used.

For use with pressure sensitive paper, U.S. Patent 2,505.470
No. 2,505,471, No. 2,505.489, 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 can 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 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, No. 091,076, and the method described in US Pat.

The capsule wall material is preferably a synthetic resin wall material, such as a polyurethane and/or polyurea material, or a melamine resin 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).
and contain it in microcapsules, paper,
A coloring agent sheet is obtained by applying it to high-quality paper, plastic sheet, resin-coated 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, benzotriazole-based ultraviolet absorbers, hindered amine-based antioxidants, hindered phenol-based antioxidants, aniline-based oxidants, etc. It is preferable to add an inhibitor, p-phenylenediamine type antioxidant, quinoline type antioxidant, etc.

In addition, an electron-accepting compound and optionally additives may be dispersed alone or in combination in a no-inner such as styrene-butadiene latex or polyvinyl alcohol, and used together with the pigments described below to produce paper, plastic sheets, resin-coated chit paper, etc. A developer sheet is obtained by applying the colorant to a 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. -144.98
No. 9, Japanese Patent Application No. 62-244.883, etc. Specifically, the electron-donating colorless dye and the electron-accepting compound are used after being pulverized and dispersed in a dispersion medium to a particle size of 10 μm or less, preferably 3 μm or less.

As the dispersion medium, an aqueous polymer solution having a concentration of approximately 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% to 300%, particularly preferably 40% to 150%, based on the electron-accepting compound.

Additives may be added to the coating liquid thus obtained 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 and metal soaps 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 increase the resistance to chemicals 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. As a binder,
Water-soluble or common, polyvinyl alcohol,
Hydroquine ethyl cellulose, hydroxypropyl cellulose, epichlorohydrin-modified polyamide, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, polyacrylic acid, polyacrylic acid amide, methylol modification Examples include polyacrylamide, starch derivatives, casein, and gelatin. 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. Coating liquid can be used on base paper, high quality paper, synthetic paper,
Coated onto plastic sheets, resin-coated paper, or acid-free paper.

Examples of thermofusible substances are disclosed in JP-A-58-57989 and JP-A-58-87094. Examples of such compounds include 2-hensyloxynaphthalene, 4-
Benzyl biphenyl, l.

2-di-m-tolyloxyethane, 1,2-diphenoxyethane, 1,4-diphenoxybutane, bis-[β-
(p-methoxyphenoxy)ethylfer, 1-phenoxy-2-p-ethylphenoquinoethane, I-p-methoxyphenoxy-2-phenoxypropane, l-phenoxy-2-p-methquinphenoquinepropane, 1 .2
-bis(p-methoxyphenoxy)propane, 1.3-
Bis(p-methoxyphenoxy)propane, 1-p-methquinphenoxo 2-0-chlorophenoxyethane,
4-(p-methoxypencylthio)anisole, l-phenoxy-2-p-methoxyphenylthioethane, 1,
2-bis(p-methoxyphenylthio)ethane, 1-p
- Ether compounds such as methylphenoxy-2-p-methoxyphenylthioethane, 4-(4-chloropencyloxy)ethoxybenzene, stearamide, methylene bisstearamide, stearanilide, behenic acid amide, stearic acid aniside , stearyl urea, etc.

Pigments include kaolin, calcined kaolin, talc, diatomaceous earth, calcium carbonate, alumina hydroxide, magnesium hydroxide, zinc oxide, lithopone, amorphous silica, colloidal silica, calcined gypsum, 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 higher fatty acid polyvalent metal salts, 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 substituted with a branched alkyl group at at least one of the 2nd and 6th positions is preferred. For example l, 1.3-)lis(2-methyl-4-hydroxy-5-t-butylphenyl)butane, l.

1.3-tris(2-ethyl-4-hydroxy-5-t
-butylphenyl)butane, 1. l,3-tris(3,
5-t-butyl-4-hydroxyphenyl)butane, 1.1.3-tris(2-methyl-4-hydroxy-
5-t-butylphenyl)propane, 4,4-butylidenebis(6-t-butyl-3-methylphenol, 4,
4-thiobis(3-methyl-6-t-butylphenol), 2,2-methylenebis(6-t-butyl-4-methylphenol), 2,2-methylenebis(6-1-butyl-4-ethylphenol) , octadecyl-3-(3
, 5-di-t-butyl-4-hydroxyphenyl)propionate, 1.3.5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis [Methylene-3-(3,5-
Examples include di-t-butyl-4-hydroxyphenyl)propinate comethane and 2,2.6.6-titramethyl-□4-piperidinyl sebacate.

The amount of the hindered phenol compound used is preferably 1 to 2001% by weight, more preferably 5 to 100% by weight, based on the electron accepting compound.

As ultraviolet absorbers, cinnamic acid derivatives, benzophenone derivatives, benzotriarylphenol derivatives, etc.
For example, butyl α-cyano-β-phenylcinnamate, 0
-benzotriazolylphenol, 0-benzotriazolyl-p-chlorophenol, 0-benzotriazolyl-p-methylphenol, 0-benzotriazolyl-2
, 4-di-t-butylphenol, 0-benzotriazolyl-2,4-di-t-octylphenol, and the like.

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 borax, polyacrylic acid, methyl vinyl ether-maleic acid copolymer, isobutylene-maleic anhydride copolymer, etc. .

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, seratins, gum arabic, casein, styrene-maleic acid copolymer hydrolyzate, Styrene-maleic acid copolymer＼
-Fester hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyacrylamide derivative, polyvinylpyrrolidone, polystyrene sodium sulfonate,
Water-soluble polymers such as sodium alginate, and water-insoluble polymers such as styrene-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, sulfosuccinic acid-based alkali metal salts, fluorine-containing surfactants, etc. are used. Specifically, G (
Sodium salts or ammonium salts such as n-hexyl)sulfosuccinic acid and di(2-ethylhexyl)sulfosuccinic acid are preferred, or anionic surfactants are effective.

The electrically conductive thermal paper is manufactured by the method described in, for example, Japanese Patent Application Laid-open No. 49-11344 and Japanese Patent Application Laid-Open No. 50-48930. Generally, a coating liquid in which a conductive substance, an electron-donating colorless dye, and an electron-accepting compound are dispersed together with a binder is applied to a support such as paper, or a conductive substance is applied to the support to form a conductive layer, and then a conductive layer is formed on the support. The electrically conductive thermal paper is manufactured by applying a coating liquid in which an electron-donating colorless dye, an electron-accepting compound, and a binder are dispersed. Note that the sensitivity can also be improved by using the thermofusible substance described above in combination.

The photosensitive pressure sensitive paper is manufactured, for example, by the method described in JP-A-57-179836. Generally, crosslinking of photopolymerization initiators such as silver bromide, silver bromide, silver behenate, Michler's ketone, benzoin derivatives, and hensifhenone derivatives with polyfunctional monomers such as polyallyl compounds, poly(meth)acrylates, poly(meth)acrylamides, etc. The agent is encapsulated in a synthetic resin capsule such as polyether urethane or polyurea together with an electron-donating colorless dye and, if necessary, a solvent. After imagewise exposure, the unexposed area is colored by contacting with an electron-accepting compound using an electron-donating colorless dye.

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

(Examples 1 to 4) Preparation of capsule sheet containing child-donating colorless dye (1) Dissolve 5 parts of a partial sodium salt of polyvinylbenzenesulfonic acid (manufactured by Nano Yonal Starch Co., Ltd., VER3A, Tl2O3) in 95 parts of hot water. After that, cool it down. A sodium hydroxide aqueous solution was added to this to adjust the pH to 4.0. On the other hand, 100 parts of diisopropylnaphthalene in which 35% of the electron-donating colorless dye shown in Table 1 was dissolved was emulsified and dispersed in 100 parts of a 5% aqueous solution of the partial sodium salt of polyvinylbenzenesulfonic acid to form particles with a diameter of 40 μm. An emulsion was obtained. Separately, 6 parts of melamine, 11 parts of a 37% by weight formaldehyde aqueous solution, and 30 parts of water were heated and stirred at 60°C, and after 30 minutes, a transparent aqueous solution of a 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 was cooled to room temperature and adjusted to pH 9.0 with an aqueous sodium hydroxide solution.

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 a microcapsule dispersion with a solid content concentration of 20%.

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

(2) Preparation of electron-accepting compound sheet 3.5-bis-α-methylpencilsalicylic 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 triethanolamine salt aqueous solution, and emulsified to give an average particle size of 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 100 parts of a 10% PVA aqueous solution and carboxylic acid. Modified SBR
10 parts of 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 16 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 at a ratio of 1:1 in terms of electron-accepting compound, and 5.0 g/m2 was applied to 50 g/m' 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 300 kg/d was applied, all of them quickly developed a blue color.

The coloring area obtained had a high density and the coloring material had excellent light resistance as shown in Table 1.

(Comparative Example) Crystal violet lactone was used as a colorless dye to obtain an electron-donating colorless dye-containing capsule sheet in the same manner as in the Examples, and a colored portion was obtained in the same manner as in the Examples.

(Lightfastness test for colored parts) The colored parts of Examples and Comparative Examples were tested with a Weather-O-meter (5
After irradiating with light for 8 hours using a kW xenon lamp, the spectral absorption of the chromophore was measured in the wavelength range of 380 to 780 nm (using Hitachi Color Analyzer Model 307), and the density at the absorption maximum was measured.

Separately, the density Do of the colored parts of Examples and Comparative Examples which were not irradiated was measured.

Table 1 shows the light resistance values determined using the following formula.

Lightfastness value=D/DO The larger the lightfastness value, the better the lightfastness of the color former.

Claims (2)

[Claims] (1) 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 is triphenyl having an alkyl group substituted with a group having antioxidant ability. Recording material characterized by using a methanophthalide derivative (2) A recording material using the compound according to claim (1), wherein the group having antioxidant ability is a hindered phenol derivative or a diarylamine derivative.