JPH0361071A - Recording material - Google Patents

Abstract

PURPOSE:To provide a recording material having a color forming part having absorption in a near infrared region and enhanced in color forming properties, raw preservability and the stability of a developed color image by using a specific compound as an electron donating leuco dye. CONSTITUTION:As an electron donating leuco dye, a compound represented by formula I is used. In the formula I, Ar1 and Ar2 are an aryl group, R1-R4 are a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an alkylthio group, an arylthio group, a cyano group, an alkoxycarbonyl group, or an aryloxycarbonyl group, R5 is a substituted sulfonyl group, a substituted phosphonyl group, a substituted amino group, an acyloxy group, an alkylthio group, an arylthio group, an alkoxycarbonyl group or an aryloxycarbonyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a recording material, and particularly to a recording material in which a color-developing portion has absorption in the near-infrared region.

(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.

In recent years, optical character reading devices and barcode reading devices have become rapidly popular, and along with this, 700nm
There has been a strong demand for recording materials that have absorption in the near-infrared region of m or more.

Several proposals have been made for electron-donating colorless dyes that absorb in the near-infrared region, such as Japanese Patent Application Laid-Open No.
No. 199757, No. 61-284485, No. 59-1
No. 48695, No. 51-121035, No. 51-12
No. 1037, No. 60230890, etc. are disclosed. However, no material has yet been obtained that has absorption in the near-infrared region and satisfies color development, shelf life, and stability of colored images.

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

(Objective of the Invention) Therefore, the object of the present invention is to have a color-forming part that has absorption in the near-infrared region, and which has good color-forming properties, shelf life, and stability of colored images, and which also satisfies other necessary conditions. The objective is to provide satisfactory recording materials.

(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 represented by the following general formula (I). This was achieved using a recording material characterized by the use of a compound that

In the above formula, A r l and A r 2 represent an aryl group, and R1
-R4 is a hydrogen atom, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an alkylthio group, an arylthio group, a cyano group, an alkoxycarbonyl group, an aryloxycarbonyl group, and R5 is a substituted sulfonyl group, a substituted phosphonyl group, a substituted amino group, acyloxy group, alkylthio group, arylthio group, alkoxycarbonyl group, and aryloxycarbonyl group.

In addition, an alkyl group represents a saturated, unsaturated or cycloalkyl group, and these are substituents such as an aryl group, an alkoxy group, an aryloxy group, an acyloxy group, a /'%rogen atom, an acylamino group, an aminocarbonyl group, or a cyano group. It may have.

In addition, the aryl group represents a phenyl group, a naphthyl group, or a heterocyclic group, and these include an alkyl group, an alkoxy group,
Substituents such as aryloxy group, halogen atom, nitro group, cyan group, substituted carbamoyl group, substituted sulfamoyl group, substituted amino group, substituted oxycarbonyl group, substituted oxysulfonyl group, alkylthio group, arylsulfonyl group, or phenyl group It may have. .

Ar1, Ar2, R1-R5 substituents have 20 carbon atoms
Below, 15 or less is particularly preferable.

Among A r l and A r 2, phenyl groups and naphthyl groups which may have substituents are preferable from the viewpoint of synthetic handling, and in particular, para-position and/or naphthyl groups are preferred from the viewpoint of coloring wavelength.
or phenyl substituted with a dialkylamino group, alkylamino group, amine group, acylamino group, diarylamino group, arylalkylamino group, arylamino group, alkyl group, alkoxy group, or halogen atom at the ortho position, more preferably at the para position and naphthyl groups are preferred.

A more preferable compound of the present invention is shown in general formula (n).

In the above formula, R1 to R5 have the above-mentioned meanings, R6 to R0 are hydrogen atoms, alkyl groups, and aryl groups, and R1° and R1 are hydrogen atoms, alkyl groups, aryl groups, alkoxy groups, aryloxy groups, and cyan groups. , a nitro group, a substituted amino group, a halogen atom, and m and n represent integers from 1 to 4.

Among the substituents represented by R1-R9, hydrogen atoms, alkyl groups having 1 to 18 carbon atoms, alkoxy groups, alkylthio groups, alkoxycarbonyl groups, and 6 to 1 carbon atoms;
2 aryl group, aryloxy group, arylthio group,
An aryloxycarbonyl group or a cyan group is preferred.

More specifically regarding R1-R4, hydrogen atoms, methyl groups,
Ethyl group, propyl group, butyl group, amyl group, hexyl group, octyl group, octadecyl group, methoxypropyl group, ethoxypropyl group, phenoxyethyl group, cyclopentyl group, cyclohexyl group, allyl group, benzyl group,
Examples include phenethyl group, phenyl group, cyano group, methoxycarbonyl group, ethoxycarbonyl group, methylthio group, and the like.

Among the substituents represented by R5, substituted sulfonyl groups having 1 to 18 carbon atoms, substituted phosphonyl groups, substituted amino groups,
An acyloxy group, an alkylthio group, an arylthio group, an alkoxycarbonyl group, and an aryloxycarbonyl group are preferred, and a substituted sulfonyl group having 1 to 18 carbon atoms, a substituted phosphonyl group, an alkylthio group, and an arylthio group are particularly preferred.

Preferred substituted sulfonyl groups and substituted phosphonyl groups are shown in the following general formulas (III) and (IV).

5O2R(III) In the above formula, R represents an alkyl group or an aryl group.

More details regarding R5 include methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, octylsulfonyl group, benzylsulfonyl group, phenethylsulfonyl group, phenylsulfonyl group, 4-tolylsulfonyl group, 4
-methoxyphenylsulfonyl group, 4-chlorophenylsulfonyl group, 4-nitrophenylsulfonyl group, 4-
Dodecylphenylsulfonyl group, 4-benzyloxyphenylsulfonyl group, 2,4-dichlorophenylsulfonyl group, naphthalen-1-ylsulfonyl group, 2-naphthylsulfonyl group, 3,4-dichlorophenylsulfonyl group, 2,5-dichlorophenylsulfonyl group , 4-N
, N-dimethylaminophenylsulfonyl group, diethylphosphonyl group, dibutylphosphonyl group, diphenylphosphonyl group, di(4-1lyl)phosphonyl group, di(4-chlorophenyl)phosphonyl group, di(4-methoxyphenyl) Phosphonyl group, di(4-nitrophenyl)phosphonyl group, di(4-cyanophenyl)phosphonyl group, di(naphthalen-1-yl)phosphonyl group, di(naphthalene-1-yl)
2-yl)phosphonyl group, di(2,4-dichlorophenyl)phosphonyl group, di(4-chloro-3-methylphenyl)phosphonyl group, anilino group, 2-chloroanilino group, benzoyloxy group, acetyloxy group, methoxycarbonyl group group, ethoxycarbonyl group, methylthio group, ethylthio group, phenylthio group, tolylthio group, benzylthio group, etc.

The R6-R11 substituents have 18 or less carbon atoms, especially 12
The following are preferred.

Among the substituents represented by R6-R8, a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, and an aryl group having 6 to 12 carbon atoms are preferred.

More specifically about R6-R9, hydrogen atom, methyl group,
Ethyl group, 1so-propyl group, n-propyl group, n-
Butyl group, 1so-butyl group, n-amyl group, 1so-
Amyl group, hexyl group, n-octyl group, 2-ethylhexyl group, octadecyl group, methoxypropyl group, ethoxypropyl group, phenoxyethyl group, cyclopentyl group, cyclohexyl group, allyl group, benzyl group, phenethyl group, tetrahydrofurfuryl group , phenyl group, tolyl group, etc.

R10% Among the substituents represented by R11, hydrogen atoms,
Alkyl group having 1 to 12 carbon atoms, aryl group having 6 to 12 carbon atoms, alkoxy group having 1 to 12 carbon atoms, allyloxy group having 6 to 12 carbon atoms, chlorine atom, bromine atom, fluorine atom, nitro A cyano group, an amino group, a mono- or dialkylamino group having 1 to 12 carbon atoms, a mono- or diarylamino group having 6 to 12 carbon atoms, and an acylamino group having 1 to 12 carbon atoms are preferred.

More details about RI Oz Rl l include 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, phenoxyethoxy group, phenoxy group, Examples include chlorine atom, bromine atom, fluorine atom, nitro group, cyano group, amine group, dimethylamino group, diethylamino group, and acetylamino group.

RIO,, R11 is -NR6R,, - from the point of coloring wavelength
The meta position relative to NR, R, is preferred.

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

(1) (2) (3) (4) (5) (7) (8) (9) (10) (11) (12) (13) (14) (15) (16) (17) (18 ) In addition, these colorless dyes are already 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; specific examples of fluorans are U.S. Pat. Nos. 3,624.107 and 3,627,78.
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 spirodipyrans 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 No. 3,775.424, Japanese Patent No. 3,853,869, Japanese Patent No. 4゜246.318, and Japanese Patent Application No. 61-240989.

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-591128'6, JP-A-60-176795, JP-A-61-9598
No. 8, U.S. Patent No. 3,767°449, U.S. Patent No. 4,219,
No. 219, No. 4,269.893, No. 4,374,6
No. 71, No. 4゜687.869, etc.

Particularly preferred are combinations with salicylic acid derivatives, phenol derivatives, metal salts of aromatic carboxylic acids, metal complexes, and acid clay. 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 2,505°470
No. 2,505,471, No. 2,505.489, No. 2,548,366, No. 2゜712.507,
2,730,456, 2,730,457, 3,103,404, 3,418,250, 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
There are interfacial polymerization methods 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: cotton, vegetable oils such as castor oil, animal oils, mineral oils, or mixtures thereof, etc.) are dissolved and dissolved in microcapsules.
A coloring agent sheet is obtained by coating paper, high-quality paper, plastic sheet, resin-coated chit 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, a quinoline antioxidant, etc.

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 pigment 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. 61-244,883, etc. Specifically, the electron-donating colorless dye and the electron-accepting compound are 10μ 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:l, particularly preferably between 1:5 and 2:3, by weight. 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 the releasability of 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 1, isobutylene-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. Coating liquid can be used on base paper, high quality paper, synthetic paper,
Plastic sheets are coated on 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-benzyloxynaphthalene, 4-
Benzyl biphenyl, di-m-)lyloxyethane, 1,
2-diphenoxyethane, ■, 4-diphenoxybutane, bis[β-(p-methoxyphenoxy)ethyl]ether, 1-phenoxy-2-p-ethylphenoxyethane, 1-p-methoxyphenoxy-2-phenoxy Propane, 1-phenoxy-2-p-methoxyphenoxypropane, 1,2-bis(p-methoxyphenoxy)propane, 1,3-bis(p-methoxyphenoxy)propane, 1-p-methoxyphenoxy-2-〇- Chlorophenoxyethane, 4-(p-methoxybenzylthio)anisole, 1-phenoxy-2-p-methoxyphenylthioethane, 1,2-bis(p-methoxyphenylthio)ethane, 1-p-methylphenoxy2- Examples include ether compounds such as p-methoxyphenylthioethane, stearamide, methylene bisstearamide, stearanilide, behenic acid amide, stearic acid aniside, and stearyl urea.

Pigments include kaolin, calcined kaolin, talc, diatomaceous earth, calcium carbonate, aluminum 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 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 1,1.3-1-
Lis(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1°1,:3-tris(2-ethyl-
4-hydroxy 5-t-butylphenyl)butane, 1.
1,3 tris(3,5-di-t-butyl-4-hydroxyphenyl)butane, 1,1.3-hlis(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(6t-butyl-4-ethylphenol), octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 1,3. 5 trimethyl-2
, 4,6-hlis(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis[methylene-3-
(3,5-di-butyl-4-hydroxyphenyl)propinate comethane, 2,2,6,6-tetramethyl-
Examples include 4-piperidinyl sebacate.

The amount of the hindered phenol compound to be used is preferably 1 to 200% by weight, more preferably 5 to 100% 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, 0-benzotriazolyl-p-chlorophenol, O-benzotriazolyl-2,4-di-t-butylphenol, 0-benzotriazolyl-2,4-di-t -Butylphenol, etc.

Water-resistant agents include water-soluble initial condensates of N-methylol urea, N-methylol melamine, urea-formalin, etc.
Examples include 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, gelatins, 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, polyvinylpyrrolidone, 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. The nine surfactants include sulfosuccinic acid alkali metal salts,
A fluorine-containing surfactant or the like is used. Specifically, sodium salts such as di(n-hexyl)sulfosuccinic acid and di(2-ethylhexyl)sulfosuccinic acid, or ammonium salts are preferred, but 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 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, and benzophenone derivatives and crosslinking agents such as polyfunctional monomers such as polyallyl compounds, poly(meth)acrylates, and poly(meth)acrylamides 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.

The electron-donating colorless dye according to the present invention has the following general formula (V
), (VI) as a raw material, known methods such as British Patent No. 2,101,648, Japanese Patent Publication No. 60-6794,
It can be easily obtained by referring to the methods of JP-A-48-729, JP-A-63-208558, JP-A-60-231766, and the like.

In the above formula, Rl, R2, A r l
etc. can be mentioned.

(Synthesis example) The compound of specific example (2) was added to a three-bottle flask equipped with a stirrer, and bis(p-N,
N-dimethylaminostyryl) carbeniram perchlorate 10 mmol, acetic acid 4TI! , take 100% of methanol and add 5% of sodium p-toluenesulfinate at room temperature.
A 100g methanol solution was added dropwise, and after the addition was complete, the mixture was stirred for an additional hour while refluxing. The reaction mixture was poured into water to obtain the desired product as pale yellow crystals. The structure is H-
Confirmed by NMR.

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

(Example 1) 20 g of each of the compound of Example (2), bisphenol A which is an electron-accepting compound, and 1,2-bis(4-methoxyphenoxy)propane which is a thermofusible substance was mixed with 100 g of 5% polyvinyl Each dispersion was obtained by dispersing it in a ball mill with an alcohol (Kuraray PVA105) aqueous solution overnight to make the volume average particle size 1.5 μm or less. In addition, 80g of calcium carbonate was added to 0.5% of sodium hexametaphosphate.
The mixture was dispersed with 160 g of the 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 a coating bar so that the dry weight of the coating layer was 5 g/m2, and
After drying at C for 1 minute, apply a super calender,
A thermosensitive recording paper was obtained.

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-
216-8MPD 1) and 100kg just before the head
When printing was carried out with a pulse width of 1.0 while using a pressure roll with a head voltage of 24 V and a pulse cycle of 10 ms using a thermal printing experimental device having a pressure roll of /cm, a green-blue image was obtained. . This colored image had absorption in the near-infrared region. Moreover, the obtained colored image showed good resistance to chemicals, sunlight, etc.

(Examples 2 to 4) In place of the electron-donating colorless dye and electron-accepting compound of Example 1, the following were used, respectively. A coated paper was obtained in the same manner as in Example 1 in other respects.

Example 2 Electron-donating colorless dye: Compound 10g12 of specific example (1)
-anilino-3-methyl-6-N,N' dibutylaminofluorane 10g Electron-accepting compound: bis(4-hydroxyphenyl)sulfone 5g 10 Danzinc benzimidazole complex 15
g Example 3 Electron-donating colorless dye: 10 g of the compound of specific example (4), 2
-Methyl-6-(4-(N-(4-N.

N-dimethylaminophenyl)amino)anilino)fluorane 10g Electron-accepting compound: 1,1-bis(4-hydroxyphenyl)cyclohexane 8g 14-β-p methoxyphenoxyethoxysalicylate zinc zinc 8g Danzinc 1-phenyl-2, 4 g of 3-dimethyl-3-pyrazolin-5-one complex Example 4 Electron-donating colorless dye: Compound Log of specific example (13),
2-anilino 3-methyl-6-N-ethyl-N-isoamylaminofluorane 6 g 13' 6°-bisdiethylamino-5-die, thylaminospiro(isobenzofuran-1,9'-fluorene)-3-one 4 g Electron-accepting compound: 10 g of bisphenol AI Og, acetylacetone complex of molybdic acid In all cases of Examples 2 to 4, the obtained colored images have absorption in the near-infrared region and are well resistant to chemicals, sunlight, etc. It showed great resistance.

(Example 5) (1) Preparation of capsule sheet containing electron-donating colorless dye 5 parts of a partial sodium salt of polyvinylbenzenesulfonic acid (manufactured by National Starch, VER3A, TL500) is dissolved in 95 parts of hot water and then cooled. . 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 3.5% of the compound of Example (9) was dissolved was emulsified and dispersed in 100 parts of a 5% aqueous solution of a partial sodium salt of the polyvinylbenzenesulfonic acid to form particles with a diameter of 4.0μ. 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. to obtain a 30% transparent aqueous solution of a melamine formaldehyde prepolymer.

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 liquid temperature was raised to 65°C, and stirring was continued for 6 hours. The 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 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 parts to 1-isopropylphenyl-2-phenyl ethane 2
0 parts 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 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 100 parts of a lO% PVA aqueous solution and carboxylic acid were added as a binder. 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 sandcliner 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 1:1 in terms of electron-accepting compound, and 5.0 g/m2 was applied to base paper of 50 g/m2.
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/crl was applied, each sheet quickly developed a green-blue color. This colored image had absorption in the near-infrared region. Moreover, the obtained colored image showed good resistance to chemicals, sunlight, etc.

(Example 6) In place of the electron-accepting compound sheet of Example 5, the following was used.

(2') Preparation of electron-accepting compound sheet Acidic clay 100
were dispersed in 400 parts of a 0.5% aqueous sodium hydroxide solution, and then 20 parts of styrene-butadiene copolymer latex (solid content) and 40 parts of a 10% starch aqueous solution were added, thoroughly stirred and mixed, and the electron accepting A compound coating solution was obtained.

5. Apply the coating solution prepared in this way to 50 g/m2 base paper.
The mixture was coated using an air knife coater so that the solid content was 0 g/m 2 and dried to obtain an electron-accepting compound sheet.

The surface of the electron-donating colorless dye-containing microcapsule sheet of Example 5 was layered on this electron-accepting compound sheet for 600 minutes.
When a load of kg/ciJ was applied, all of them quickly developed a green-blue color. This colored image had absorption in the near-infrared region. Moreover, the obtained colored image showed good resistance to chemicals, sunlight, etc.

Claims (1)

[Scope of Claims] In a recording material that utilizes color development due to contact between an electron-donating colorless dye and an electron-accepting compound, a compound represented by the following general formula (I) is used as the electron-donating colorless dye. Recording materials featuring ▲ Contains mathematical formulas, chemical formulas, tables, etc. ▼ (I) In the above formula, Ar_1 and Ar_2 represent aryl groups, and R_1 to R
_4 is a hydrogen atom, alkyl group, alkoxy group, aryl group, aryloxy group, alkylthio group, arylthio group, cyano group, alkoxycarbonyl group, aryloxycarbonyl group, R_5 is a substituted sulfonyl group, substituted phosphonyl group, substituted amino group , represents an acyloxy group, an alkylthio group, an arylthio group, an alkoxycarbonyl group, or an aryloxycarbonyl group.