JPH03138190A - Recording material - Google Patents

Abstract

PURPOSE:To enhance color forming properties and the light fastness of a leuco dye and an image by containing a specific fluorane derivative as an electron donating leuco dye. CONSTITUTION:In a recording material using an electron donating leuco dye and an electron acceptive compound, a fluorane derivative wherein the second position is substituted with a dialkylamino group and the third position is substituted with a halogen atom, an alkyl group or an alkoxy group and the sixth position is substituted with an amino residue is contained as the electron donating leuco dye. By this method, the material for the recording material improved in developed color density, color forming sensitivity, the fastness of a developed color image and the fastness of the leuco dye and having good characteristics such as oil solubility, water solubility, a distribution coefficient, pKa, the polarity and position of a substituent, crystallinity in mixed use, a change of solubility or the like is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a recording material, and particularly to a recording material with improved color development, leuco bodies, and light resistance of images.

(Prior art) Recording materials using electron-donating colorless dyes and electron-accepting compounds include pressure-sensitive paper, thermal paper, and photosensitive pressure-sensitive paper.

It is already well known as electrically conductive thermal recording paper, thermal transfer paper, etc. For example, UK patent 2140449, US patent 44
80052, 4436920, Special Publication Showa 60-2399
2. JP-A-57-179836, JP-A No. 60-123556
, 60-123557 etc. for details.

As a recording material, research has been conducted in recent years to improve properties such as (1) color density and color sensitivity, (2) fastness of color bodies, and (3) fastness of leuco bodies.

The present inventors have investigated the oil solubility, solubility in water, partition coefficient, pKa, polarity of substituent, position of substituent, crystallinity when mixed, for each of the electron donating colorless dye and the electron accepting compound. Focusing on characteristics such as changes in solubility, we have pursued the development of good materials for recording materials and recording materials.

(Object of the Invention) Therefore, the object of the present invention is to provide a recording material using a material that has good color development, leuco bodies, and light fastness of images, and also satisfies other necessary conditions.

(Structure of the Invention) The object of the present invention is to provide an electron-donating colorless dye in which the 2nd position is a dialkylamino group, the 3rd position is a halogen atom, and an alkyl group.
Alternatively, this was achieved using a recording material characterized by containing a fluoran derivative in which the alkoxy group and the 6th position were substituted with an amine residue.

Among the fluoran derivatives according to the present invention, in order to obtain a black hue, it is preferable that the alkyl groups of the dialkylamino group at the 2-position bond to each other to have a cyclic structure; Otherwise, it is difficult to obtain a black color with the dialkylamino group at the 2-position.

Further, in order to improve the light resistance of the leuco body and color former, it is preferable that the 3-position is a lower alkyl group such as a methyl group.

That is, the 2nd position is a cyclic amino group, the 3rd position is a lower alkyl group,
Fluorane derivatives in which the 6-position is substituted with an amine residue are preferred.

Among these, those represented by the following general formula (1) are preferred.

(In the formula, R1 and R2 may be the same or different and may be a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group,
A represents an aralkyl group or an aryl group, A represents a cyclic amino group which may contain a hetero atom and an unsaturated bond, and X represents a halogen atom, an alkyl group or an alkoxy group. ) In the above general formula (I), the groups represented by RI and R2 further include an alkyl group, an alkenyl group, an alkynyl group,
It may be substituted with an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, a halogen atom, a substituted amino group, a cyano group, a nitro group, an acyl group, a trihalomethyl group, a sulfamoyl group, a heterocyclic residue, or the like. These substituents may further have a substituent.

R1 and R1 may be bonded to each other to have a cyclic structure that may contain a heteroatom and an unsaturated bond,
The ring may have a substituent.

RI and R1 are an alkyl group having 1 to 20 carbon atoms, an alkoxyalkyl group having 2 to 20 carbon atoms,
Aryloxyalkyl group having 7 to 20 carbon atoms, aryl group having 6 to 20 carbon atoms, 7 to 2 carbon atoms
Preferred are aralkyl group, tetrahydrofurfuryl group, and tetrahydro(2H)pyranyl group. In particular, alkyl groups having 1 to 10 carbon atoms, alkoxyalkyl groups having 2 to 10 carbon atoms, aryloxyalkyl groups having 7 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, 7 carbon atoms to 10 aralkyl groups and tetrahydrofurfuryl groups are preferred.

-NSN-diethylamino group, N5N-dibutylamino group, N,N-dialkylamino group, N-ethyl-N-isopentylamino group, N-ethyl-N-p-tolylamino group, N-ethyl-N-tetrahydrofur furylamino group, N-ethyl-N-cyclohexyruamino group, N-
Ethyl-N-(3-ethoxypropyl)amino group, N-
Ethyl-N-(3-phenoxyprobyl)amino group and the like are preferred.

In the above formula, the group represented by A is preferably a cyclic amino group which may contain a hetero atom having 2 to 10 carbon atoms and an unsaturated bond, and particularly a pyrrolidinyl group, a piperidino group,
Morpholino group and hexamethyleneimino group are preferred. These may be further substituted with an alkyl group. In the above formula, the group represented by X is a fluorine atom, a chlorine atom, a bromine atom,
An alkyl group having 1 to 10 carbon atoms and an alkoxy group having 1 to 10 carbon atoms are preferred, particularly an alkyl group having 1 to 10 carbon atoms, and particularly an alkyl group having 1 to 10 carbon atoms.
-4 alkyl groups are preferred.

As a combination of A and X, it is particularly preferable that A is a cyclic amino group and X is a methyl group.

The xanthine ring and the 9-position phthalide ring thereof may have a nuclear substituent, and the substituent in this case is preferably an alkyl group, an alkoxy group, an alkylthio group, a halogen atom, or the like.

Next, specific examples of fluoran derivatives according to the present invention will be shown, but the present invention is not limited thereto.

(1) 2-pyrrolidinyl-3-methyl-6-N,N-diethylaminofluorane (2) 2-pyrrolidinyl-3-methyl-6-N,N-dimethylaminofluorane (3) 2-pyrrolidinyl-3- Methyl-6-N,N-dibrobylaminofluorane (4) 2-pyrrolidinyl-3-methyl-6-N,N-dibutylaminofluorane (5) 2-pyrrolidinyl-3-methyl-6-N, N-dibutylaminofluorane (6) 2-pyrrolidinyl-3-methyl-6-N-ethyl-N-(3-ethoxypropyl)aminofluorane (7) 2-piperidino-3-methyl-6-NSN-diethylamino Fluoran (8) 2-piperidino-3-methyl-6-N-ethyl-
N-isopentylaminofluorane (9) 2-morpholino-3-methyl-6-N,N-dipentylaminofluoran 0ω 2-pyrrolidinyl-3-methyl-6-N-ethyl-N-p-)lylamino Fluoran 01) 2-pyrrolidinyl-3-methyl-6-N-ethyl-N-tetrahydrofurfurylaminofluorane (1) 2-pyrrolidinyl-3-methoxy-6-N1N
-dibutylaminofluorane (13) 2-pyrrolidinyl-3-fluoro-6-N
1N-dibutylaminofluorane +14) 2-pyrrolidinyl-3-methyl-6-N-
Ethyl-N-(3-(4-methoxyphenoxy)propylcoaminofluorane 05) 2-hexamethyleneimino-3-methyl-6
-N1N-diethylaminofluorane and the like.

Electron-donating colorless dyes according to the present invention include conventionally known triphenylmethane phthalide compounds, fluoran compounds, phenothiazine compounds, indolyl phthalide compounds, leuco auramine compounds, rhodamine lactam compounds, triphenyl It can be used in combination with various compounds such as methane compounds, triazene compounds, spiropyran compounds, and fluorene compounds.

Specific examples of phthalides are given in U.S. Reissue Patent Specification No. 23.0.
No. 24, U.S. Patent Nos. 3,491,111, 3,491,112, 3,491.116 and 3,509,174.

Specific examples of fluorans are given in U.S. Pat. No. 3,624.
No. 107, No. 3,627,787, No. 3,641
．． C111, No. 3,462,828, No. 3.6
No. 81.390, No. 3,920.510, No. 3,
No. 959,571, specific examples of spiropyrans are given in U.S. Patent No. 3,971.808, and pyridine and pyrazine compounds are given in U.S. Patent No. 3,775,424.
issue.

No. 3,853,869, No. 4,246,318, and specific examples of fluorene compounds are given in Japanese Patent Application No. 61-2409.
It is described in No. 89 etc.

As the electron-accepting compound used in the recording material of the present invention, phenol derivatives, salicylic acid derivatives, metal salts of aromatic carboxylic acids, organic complexes of rhodan zinc, and the like are preferable.

If acid clay is used, the hue may be reddish and black cannot be obtained.

Examples of preferred electron-accepting compounds are disclosed in Japanese Patent Publication No. 40-9309.
No. 45-14039, Japanese Patent Publication No. 52-1404
No. 83, JP-A-48-51510, JP-A-57-21
No. 0886, JP-A-58-87089, JP-A-59-
No. 11286, JP-A-60-176795, JP-A-6
No. 1-95988, etc.

Examples of electron-accepting compounds include bisphenol A, 2
．． 2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)hebutane, 1. l-bis(4-hydroxyphenyl)butane, 1. l-bis(4-hydroxyphenyl)-2-ethylhexane.

1.1-bis(3-10-4-hydroxyphenyl)
-2-ethylbutane, bis(3-allyl-4-hydroxyphenyl)sulfone, 1,7-bis(4-hydroxyphenylthio)-3,5-dioxahebutane, (4-hydroxyphenyl)-(4-propyl) quinphenyl) sulfone, 4-hydroxybenzoic acid benzyl ester, 2,
4-dihydroxybenzoic acid-β-phenoxyethyl ester.

2.4 Dihydroxybenzoic acid-α-methyl-β-(3-
Methoxyphenoxy)ethyl ester l t.

3-bis(4-hydroxyphenyl)propane.

Examples include 2-(2,4 dihydroxyphenyl)-2-phenylpropane and zinc 3,5-bis(α-methylbenzyl)salicylate.

When the recording material of the present invention is used for thermal paper.

Japanese Unexamined Patent Publication No. 62-144,989, patent application No. 62-244.
It takes the form as described in the specification of No. 883, etc.

Specifically, the electron-donating colorless dye and the electron-accepting compound are 1Oμ or less in the dispersion medium.

The dispersion medium that is preferably ground and dispersed to a particle size of 3 μ or less is generally an aqueous polymer solution with a concentration of about 0.5 to 10%. etc. is used.

The ratio of the electron-donating colorless dye to the electron-accepting compound used is preferably between 1=10 and 1=1, and particularly preferably between 1:5 and 2:3.

At that time, a thermofusible substance can be included in the thermosensitive coloring layer in order to improve thermal responsiveness. Representative thermofusible substances include aromatic ethers, thioethers, esters, and/or aliphatic amides or ureides.

Examples of these are JP-A-58-57989 and JP-A-58-87.
No. 094, No. 61-58789, No. 62-10968
No. 1, No. 62-132674, No. 63-151478
No. 63-235961, patent application No. 1-4447,
It is described in No. 1-37070.

Examples of thermofusible substances include phenethyl biphenyl ether, benzyloxynaphthalene, benzylbiphenyl, 1,2-diphenoxyethane, 1,2-di-m-)zyloxyethane, 1-phenoxy-2-p-methoxy Phenoxyethane, 1-p-methoxyphenoxy-2-〇-chlorophenoxyethane, l,2-di-p-fluorophenoxyethane, l,3-di-p-methoxyphenoxypropane, 1,2-di-p- Methoxyphenoxypropane, l-phenoxy-2-p-methoxyphenoxypropane, 1-p-methoxyphenoxyethoxy-2-p
-methoxyphenoxyethane, 1,2-di-p-methoxyphenylthioethane, p-methoxybenzyloxytolylmethane, (4-methoxybenzyloxy)-(3-
Methyl-4-chlorophenyl)methane, p-chlorobenzyloxy-p-ethoxyphenylmethane, and the like.

These are used in finely dispersed form at the same time as the electron-donating colorless dye or simultaneously with the electron-accepting compound. The amount used is 20% or more and 300% or less by weight relative to the electron-accepting compound, and preferably 40% or more and 15°0% or less.

Additives may be added to the thus obtained coating liquid as necessary to meet various requirements. An example of an additive is an inorganic pigment in the binder to prevent staining of the recording head during recording.

Oil-absorbing substances such as polyurea fillers are dispersed, and fatty acids, metal soaps, and the like are added to improve mold release properties from the head. Therefore, in general, in addition to electron-donating colorless dyes and electron-accepting compounds that directly contribute to color development, thermofusible substances, pigments, waxes,
Additives such as antistatic agents, ultraviolet absorbers, antifoaming agents, conductive agents, fluorescent dyes, and surfactants are coated on the support to form a recording material.

Furthermore, if necessary, a protective layer 11 may be provided on the surface of the heat-sensitive recording layer, two or more protective layers may be laminated as necessary, and a protective layer 11 may be provided on the back surface to correct the curl balance of the support. A coating liquid similar to that of a protective layer may be applied to the back side for the purpose of improving the chemical resistance against chemicals, or 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 and hydroxyethyl cellulose.

Hydroxypropylcellulose, epichlorohydrin-modified polyamide, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer.

Isobutylene-maleic anhydride copolymer.

Polyacrylic acid, polyacrylic acid amide, methylol-modified polyacrylamide, starch derivatives.

Examples include casein and gelatin. In addition, water-resistant agents are added to these binders for the purpose of imparting water resistance.
Emulsions of hydrophobic polymers, specifically styrene-butadiene rubber latex.

Acrylic resin emulsion etc. can also be added.

The obtained heat-sensitive coating liquid is applied to high-quality paper, high-quality paper with an undercoat layer, synthetic paper, plastic film, etc. In this case, it is particularly preferable to use a support having a smoothness defined by JIS-8119 of 500 seconds or more, particularly 800 seconds or more, from the viewpoint of dot reproducibility.

When providing an undercoat layer mainly composed of pigments on a support, all general organic or inorganic pigments can be used, but in particular those with an oil absorption of 40 cc/100 g or more as specified in JIS-5101. Preferably, calcium carbonate, barium sulfate, titanium oxide,
Examples include talc, waxite, kaolin, calcined kaolin, aluminum hydroxide, amorphous silica, urea-formalin resin powder, polyethylene resin powder, and the like.

When applying these pigments to a support, the amount of pigment is 2
g/m" or more, preferably 4 g/m2 or more.

Binders used in the undercoat layer include water-soluble polymers and water-insoluble binders, and the binders may be used alone or in combination of two or more.

Examples of water-soluble polymers include methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, ethylene-maleic anhydride copolymer hydrolyzate, and isobutylene. -Maleic anhydride copolymer hydrolyzate, polyvinyl alcohol,
- Ruboxy-modified polyvinyl alcohol, polyacrylamide, and the like.

As the water-insoluble binder, synthetic rubber latex or synthetic resin emulsion is generally used, and examples include styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion. .

The amount of the binder used is 3 to 100% by weight, preferably 5 to 50% by weight, based on the pigment. Wax, anti-fading agent, surfactant, etc. may be added to the undercoat layer.

Pigments used as additives in the present invention include kaolin, calcined kaolin, talc, waxite, diatomaceous earth, calcium carbonate, and aluminum hydroxide.

Magnesium hydroxide, zinc oxide, lithopone, amorphous silica, colloidal silica, calcined gypsum, silica, magnesium carbonate, titanium oxide, alumina.

Examples of metal soaps include barium carbonate, barium sulfate, mica, microballoons, urea-formalin fillers, polyester particles, cellulose fillers, and higher fatty acid polyvalent metal salts 2, such as zinc stearate and aluminum stearate.

Examples include calcium stearate and zinc oleate.

Further, in the present invention, it is preferable to use a wax having a melting point of 40 DEG to 120 DEG C. in view of head matching properties for facsimiles.

The wax has a melting point of 40 to 120°C, and includes paraffin wax, polyethylene wax, carnauba wax, microcrystalline wax, camphoria wax, montan wax, fatty acid amide wax, and the like.

Among these, paraffin wax, microcrystalline wax, montan wax, and fatty acid amide wax are preferred, and paraffin wax, montan wax, and methylolstearamide having a melting point of 50 to too'c are particularly preferred.

The amount of wax used is 5 to 200% of the electron-donating colorless dye.
% by weight, preferably 20-150% by weight.

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.

Examples of the radiation absorber include cinnamic acid derivatives, benzophenone derivatives, benzotriazolylphenol derivatives, etc., such as α-cyano-β-phenylbutyl cinnamate, 0-benzotriazolylphenol, 0-benzotriazolyl-p -chlorophenol, 0-benzotriazolyl-2
, 4-di, monobutylphenol, 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;
Examples include blend heat treatment of nodialdehyde compounds such as glyoxal and glutaraldehyde, inorganic crosslinking agents such as boric acid and borax, polyacrylic acid, methyl vinyl ether-maleinthane copolymer, isobutylene-maleic anhydride copolymer, and the like.

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 glossy carboxymethylcellulose, hydroxymethylcellulose, gelatins, gum arabic, casein, styrene-maleic acid copolymer hydrolyzate, styrene-maleic acid copolymer Water-soluble polymers such as polymer half ester hydrolysates, isobutylene-maleic anhydride copolymer hydrolysates, polyacrylamide derivatives, polyvinylpyrrolidone, polystyrene sodium sulfonate, and sodium alginate, and styrene-butadiene rubber latex, Water-insoluble polymers such as acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion are used.

In addition, pigments, metal soap, and wax are added to the protective layer to improve mating performance with the thermal head.

A waterproofing agent or the like may be added.

Also, when applying a protective layer onto a thermosensitive coloring layer.

In order to obtain a uniform protective layer, a surfactant may be added. Examples of the surfactant include sulfosuccinic acid-based alkali metal salts, fluorine-containing surfactants, and the like. Specifically, sodium salts or ammonium salts such as di(n-hexyl)sulfosuccinic acid and di(2-ethylhexyl)sulfosuccinic acid are preferred, but anionic surfactants are effective.

For use with pressure sensitive paper, U.S. Patent No. 2,505.47
No. 0, No. 2,505,471, No. 2゜505.489
No. 2,548,366, No. 2,712,507, No. 2,730,456, No. 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 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.

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 acid 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, resins, etc. A coloring agent sheet is obtained by applying it to coated paper, etc.

In addition, an electron-accepting compound and, if necessary, additives, alone or in combination, are dispersed in a binder such as styrene-butadiene latex or polyvinyl alcohol, and the pigment is used together with a support such as paper, plastic sheet, or resin-coated paper. A developer sheet is obtained.

As a binder, the combination of carboxy-modified styrene-butadiene latex and water-soluble polymer improves light resistance,
It is preferable from the point of view of water resistance, and the average particle size of the pigment is 5.
．． From the viewpoint of color developing ability, it is preferable to use calcium carbonate with a particle size of 0 μ or less in an amount of 60% by weight or more of the total pigment.

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.

(Examples of the invention) Examples are shown below, but the present invention is not limited thereto.2% by weight unless otherwise specified in the examples.
represents.

Example-1 1) Preparation of capsule sheet containing electron-donating colorless dye 5 parts of a partial sodium salt of polyvinylbenzenesulfonic acid (manufactured by National Starch Co., Ltd., VERSA, Tl2O3) are dissolved in 95 parts of water. A sodium hydroxide aqueous solution was added to this to adjust the pH to 4.0.

On the other hand, 4.5% of 2-pyrrolidinyl-3-methyl-6-N,N-dibutylaminofluorane, an electron-donating colorless dye,
100 parts of dissolved diisopropylnaphthalene was emulsified and dispersed in 100 parts of a 5% aqueous solution of the partial sodium salt of polyvinylbenzenesulfonic acid to obtain an emulsion having a particle size of 4.0 μm in diameter. Separately, 6 parts of melamine, 11 parts of a 37% by weight aqueous formaldehyde solution, and 30 parts of water were heated and stirred at 60'C to obtain a transparent aqueous solution of a melamine-formaldehyde initial polymer. This aqueous solution was mixed with the above emulsion.

While stirring, the pH was adjusted to 6.0 with an aqueous 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 with an aqueous sodium hydroxide solution.
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 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 the solid content was 5 g/m'', and dried to obtain a capsule sheet containing an electron-donating colorless dye.

2) Preparation of electron-accepting compound sheet 3. Zinc 5-bis(α-methylbenzyl)salicylate 1
A dispersion liquid consisting of 4 parts of calcium carbonate, 80 parts of calcium carbonate, 20 parts of zinc oxide, 1 part of sodium hexametaphosphate and 200 parts of water was dispersed using a sand glider so that the average particle size was 3 microns. To this dispersion were added 100 parts of a 10% PVA aqueous solution and 10 parts of carboxy-modified SBR latex (as solid content), and water was added so that the solid content concentration was 20%.

A coating liquid was obtained. Apply 5゜0g of this coating liquid to 50g/m" base paper.
The mixture was coated using an air knife coater so that a solid content of 1/m'' was coated, and dried to obtain an electron-accepting compound sheet.

The sheet side of the microcapsules containing an electron-donating colorless dye was layered on an electron-accepting compound sheet and colored under a load of 400 kg/cm' to obtain a dark black color image. Both the light fastness of this black color image and the light fastness of the uncolored area were excellent.

Example-2 2-pyrrolidinyl-3-methyl-6-N,N-diethylaminofluorane, which is an electron-donating colorless dye, bisphenol A, which is an electron-accepting compound, and 1-phenoxy-, which is a thermofusible compound. 20g of each 2(4-methoxyphenoxy)propane was dispersed with 100g of a 5% polyvinyl alcohol (Kuraray PVA105) aqueous solution in a Pall mill overnight to give a volume average particle size of 3μ. On the other hand, 80 g of calcined kaolin (Anisilex-93) was dispersed with 160 g of a 0.5% solution of sodium hexametaphosphate using a homogenizer.

After dispersing as described above, each dispersion was mixed in a ratio of 5 g of the electron-donating colorless dye dispersion, log of the electron-accepting compound dispersion, 10 g of the diaryloxyalkane compound dispersion, and 22 g of the calcined kaolin dispersion.

Additionally, 4 g of zinc stearate emulsion and 2% (
A coating liquid was obtained by adding 5 g of an aqueous solution of sodium 2-ethylhexyl sulfosuccinate. 9 tsubo weight 50 of this coating liquid
g/m" high-quality paper with a wire bar to a dry coating amount of 6 g/m", and subjected to calender mite treatment to obtain a coated paper.

The coated paper obtained in the above manner was coated with a thermal printing experimental device having a Kyocera ■ thermal head (KLT-216-8MPDI) and a pressure roll of 1OG kg/ci just before the head, with a head voltage of 24v1 and a pulse cycle of 10.
While using the pressure roll under the conditions of m5, the pulse width was set to 1.
．． When printed with 0 and allowed to develop color, the developed color hue was deep black. Both the light fastness of this black color image and the light fastness of the uncolored area were excellent.

Example-3 2-pyrrolidinyl-3-methyl-6-N of Example-2,
N-diethylaminofluorane, 2-pyrrolidinyl-
A coated paper was obtained in the same manner as in Example 2, except that 3-methyl-6-N-ethyl-N isopentylaminofluorane was used. When the color was developed in the same manner as in Example 2, the color hue was deep black. Both the light fastness of this black color image and the light fastness of the uncolored area were excellent.

Claims (1)

[Claims] In a recording material using an electron-donating colorless dye and an electron-accepting compound, the electron-donating colorless dye has a dialkylamino group at the 2nd position, a halogen atom, alkyl group or an alkoxy group at the 3rd position, and an amine residue at the 6th position. A recording material characterized by containing a substituted fluorane derivative.