JPS6394882A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance the coloring properties and the shelf stability of a coloring image, by incorporating a bissalicylic acid derivative or the metallic salt thereof as an electron accepting compound. CONSTITUTION:As an electron accepting compound coloring due to the contact of a colorless dye, a bissalicylic acid derivative or the metallic salt thereof is used. As the bissalicylic acid derivative, 2,2-bis(carboxy-4-hydroxyphenyl) propane, 1,1-bis(3-carboxy-4-hydroxyphenyl)-2-ethylhexane, 2,2-bis(3-carboxy-4- hydroxyphenyl)butane, the metallic salt thereof, and the like are used in single or mixed form. This recording material minimizes the possibility of fogging, decoloring in a coloring area, or the like due to chemicals.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a heat-sensitive recording material, and particularly to a recording material with improved color development and stability of color images.

(Prior Art) Recording materials using an electron-donating colorless dye and an electron-accepting compound are already well known as pressure-sensitive paper, thermal paper, light-sensitive pressure-sensitive paper, current-carrying thermal recording paper, thermal transfer paper, and the like. For example, British patent, 2/'AO1It≠ri, US patent t/Lt
alooj2, the same group≠36720. % Kimiaki/,,0-,
! 3.92.2, Japanese Patent Application Publication No. 37-779゜za 3 Otsu, 60
-/23. I am familiar with JJA, 1.0-/23.337, etc.

The performance that a recording material should have is (1) sufficient color density and color development sensitivity, (2) no fogging, (3) sufficient fastness of color body, and (4) color development. (5) the S/to ratio should be adequate; and (6) the coloring material should have sufficient chemical resistance.

In particular, heat-sensitive recording materials have the disadvantage that fogging occurs due to solvents and the like, and the color formers undergo discoloration and fading due to oils, fats, chemicals, and the like. Therefore, when it comes into contact with stationery and office supplies such as water-based ink, oil-based ink, light pen, ink, adhesive, glue, diazo developer, or cosmetics such as hand cream and emulsion, the white part may develop color. The coloring part caused discoloration and fading, which seriously impaired the commercial value. , pKa We have pursued the development of good recording materials and recording materials by focusing on characteristics such as the polarity of the substituent, the position of the substituent, and changes in crystalline solubility when mixed.

(Object of the Invention) Therefore, an object of the present invention is to provide a recording material using a material that has good color development properties and stability of color images, and also satisfies other requirements.

(Structure of the Invention) An object of the present invention is to provide a heat-sensitive recording material that utilizes the phenomenon in which a colorless dye is colored when it comes into contact with an electron-accepting compound, and which contains a bissalicylic acid derivative or a metal salt thereof as the electron-accepting compound. This achievement was achieved by using a heat-sensitive recording material that is characterized by its unique features.

Among the salicylic acid derivatives according to the present invention, those represented by the following general formula are preferred.

In the formula, R represents a divalent group, X represents a hydrogen atom, an alkyl group, a phenyl group, an alkoxy group, or a halogen atom, and M
represents a hydrogen atom or an n-valent metal atom, and n represents an integer.

Number of carbon atoms in the divalent group represented by R in the above formula /~/
A divalent group having 1 to 2 carbon atoms is preferred, and an alkylene group having 1 to 2 carbon atoms, a cycloalkylene group having 3 to 7 carbon atoms, and an aralkylene group having 7.2 to 7.2 carbon atoms are particularly preferred.

Among the substituents represented by X, hydrogen atoms, number of carbon atoms/
~/g of alkyl group, number of carbon atoms/~,! 0 alkoxy group, phenyl group, chlorine atom and fluorine atom are preferred, and among the groups represented by M, hydrogen atom, lead, aluminum, magnesium and calcium are preferred.

Next, specific examples of salicylic acid derivatives according to the present invention are shown,
The present invention is not limited to these (Ivl).

)1. ! -bis(3-carboxy-≠-hydroxyphenyl)furopane, /l/-bis(3-carboxy-≠-
Hydroxyphenyl)-noethylhexane 1.2. ．．
2-His(3-carboxy-4'-hydroxyphenyl)butane, /, ≠-bis(3-carpoquin-q-hydroxycumyl)benzene, /, 3-bis(3-carboxy-≠-hydroxycumyl)benzene , /, /-hiss (3
-Carphoky7-4'-hydroxyphenyl)cyclohexane, bis(,2-hydroxy-3-carboxyne-3-
chloro)methane, bis(,2-hydro-+y-3-carboxyj-octyl)methane, his(,2-hydroxy-3-carboxy-j~α-phenethyl)methane and their metal salts, etc. , these may be used alone or in combination.

These may form metal salts and then be used in finely dispersed form, or they may be used in finely dispersed form in the coexistence of metal compounds such as zinc oxide.

The salicylic acid derivative according to the present invention may be used in combination with well-known electron-accepting compounds other than the present invention, such as salicylic acid derivatives, phenol derivatives, phenol resins, and acid clay.

Some examples of these include ≠-ternary butylphenol, gouphenylphenol, ≠monohydroxydiphenoxide α-naphthol, β-naphthol, hexyl-guhydroxybenzoate 1.2. ．． 2'-dihydroxybiphenyl, 22.2-bis(terhydroxyphenyl)propane (hisphenol A), 4Z,
≠′-isopropyritenebinu(,2-methylphenol), /,/′-bis(3-chloro-≠-hydroxyphenyl)cyclohexane, /,/-bis(3-chloro-
≠-Hydroxyphenyl)-2-ethylbutane, ≠.

q'-Secondary-isooctylene diphenol,
Gutcrt-octylphenol, 71II'-5e
C-butylidene diphenol, μ-p-methylphenylphenol, ≠, 4”-isobentritine phenol, bis-3-T+) Roux II-hydroxyphenylsulfone, +, p′-methipanechlorhexylitine diphenol, ≠, ≠′-dihydroxydiphenyl sulfide, /, ≠-bis(μ′-hydroxycumyl) Hensen, /.

3-his-(j'-hydroxycumyl)be/cene, u,
4''-thiobis(ot-tert-butyl-3-ot-methylphenol), ≠, ≠'-dihydroxydiphenyl sulfone, hydroquinone monobenzyl ether,
≠-hydroxybenzophenone, 2゜≠-dihydroxybenzophenone, polyvinylbenzyloxyphenol, 2. ≠, v′-trihydroxybenzophenone %jl+2′#≠.

≠′-tetrahydroxybenzophenone, ≠-hydroxyphthalic acid, dimethyl-≠-methyl hydroxybenzoate, 2. ≠, v′-trihydroxydiphenylsulfone, /, j-bis-p-hydroxyphenylpentane, /
, Otsu-his-p-hydroxyphenoxyhexane, Hiro-
Tolyl hydroxybenzoate, Hiro-hydroxybenzoic acid α
-Phenylbenzyl ester, Hiro-phenylpropyl hydroxybenzoate, ≠- phenethyl hydroxybenzoate, ≠-p-chlorobenzyl hydroxybenzoate, ≠-
Hydroxybenzoic acid-p-methoxyhensyl, ≠-hydroxybenzoic acid henzyl ester, q-hydroxybenzoic acid-p-methoxyhensyl esfur, ≠-hydroxybenzoic acid-β-phenethyl ester, Hiro-hydroxy -2
′,≠′-dimethyldiphenylsulfone β-phenethyl orselinate, cinnamyl orselinate, orserinic acid-〇-chlorophenoxyethyl ester, 0-
Ethylphenoxyethyl orseinate, O-phenylphenoxyethyl orseinate, m-phenylphenoxyethyl orse+)ate, co,+-dihydroxybenzoic acid-β-3'-1-butyl-hiro'-hydroxyphenoxyethyl ester , /-t-butyl-≠-p-hydroxyphenylsulfonyloxybenzene, ≠-benzylsulfurylphenol, 2.4t-') hydroxybenzoic acid-β-phenoxyethyl ester, -1
≠-dihydroxy-6-methylbenzoic acid benzyl ester, bis-gu-hydroxyphenylacetate methyl, ditolylthiourea, ≠, j′~diacetyldiphenylthiourea, 3-phenylsalicylic acid, 3-7 chlorohexylsalicylic acid, 3. j-tert-butylsalicylic acid,
3-Methyl-3-benzylsalicylic acid,! -Phenyl-3-(α,α-dimethylbenzyl)salicylic acid, 3゜j
-di(α-methylbenzyl)salicylic acid, j-1-octylsalicylic acid, 3. J-di-t-butylsalicylic acid, 3-chloro-3-cumylsalicylic acid, 3-methyl-,
5-1-octylsalicylic acid, 3-methyl-j-α-methylbenzylsalicylic acid, 3-methyl-3-cumylsalicylic acid, 3. j-di-t-amylsalicylic acid, 3-phenyl-3-benzylsalicylic acid, 3-phenyl-J-1
-octylsalicylic acid, 3-phenyl-j-α-methylbenzylsalicylic acid, 3. ．． 3-di-t-octylsalicyl full, 3.3-bis(α-methylhensyl) salicyl/l/acid, 3. j-Dicumylsalicylic acid, Hiro-methyl-J-(α-methylbenzyl)salicylic acid, ≠-methyl-j-cumylsalicylic acid, 3-(α-methylbenzyl)
-6-methylsalicylic acid, 3-(α-methylbenzyl)
-6-phenylsalicylic acid, 3-toIJ phenylmethylsalicylic acid, 3-diphenylmethylsalicylic acid, 1l-
n-dodecylsalicylic acid, p-t-dodecylsalicylic acid, II-n-dodecylsalicylic acid, ≠-n-pentadecylsalicylic acid, 4<-n-heptadecylsalicylic acid, !
-(/,3-diphenylbutyl)-salicylic acid, j-n
-octadecylsalicylic acid, j-dodecylsulfonylsalicylic acid, j-dodecylsulfosalicylic acid, j-(p-
α-methylbenzyl) α-methylbenzylsalicylic acid,
Examples include 3-methyl-yo-dodecylsulfosalicylic acid.

The electron-accepting compound is the tO-J of the electron-donating dye precursor.
It is preferable to use '00% by weight, more preferably 700 to 100% by weight. The electron-accepting compound described above is preferably mixed with the salicylic acid derivative, which is the electron-accepting compound according to the present invention, in a ratio of 1.2000 to IO weight ratio.

Further, two or more of the above electron-accepting compounds may be used in combination.

-/O- Electron-donating colorless dyes according to the present invention include triphenylmethane phthalide compounds, fluoran compounds, phenothiazine compounds, indolyl phthalide compounds, leuco auramine compounds, rhodamine lactam compounds, and There are various compounds such as phenylmethane compounds, triazene compounds, and spiropyran compounds. Specific examples of phthalides are U.S. Patent Reissue No. 23.02≠, U.S. Pat. ≠ri／,／／No.2,
Same 3rd. ≠ri/, No. 111 and No. 3 of the same. jOri, /7
≠, specific examples of fluorans are given in U.S. Patent No. 3.62≠,
No. 707, same No. 3. t27, 7+7, same No. 3. t4A
/, 0// No. 3. ≠No. 62.121 and No. 3
．． All, 390, U.S. Patent No. 3. tt/, No. 320, U.S. Pat.
? Specific examples of spiropyrans are described in U.S. Pat. No. 3,771 and U.S. Pat. , IJt3, Za6ri, US Patent No. V211t3Ir, etc. Some examples of these are triarylmethane compounds,
3,3-bis(p-dimethylaminophenyl)-4-dimethylaminophthalide (i.e. crystal violet lactone), 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)- 3
-(/,3-dimethylindol-3-yl)phthalide, 3(p-')methylaminophenyl)-J-(s-methylindol-3-yl)phthalide, etc., diphenylmethane compounds include , Hiroshi, j'-bis-dimethylaminobenzhydrin benzyl ether/L, ,N
, lophenyleucoauramine, N-2+”
+ j -Trichlorophenylleucoolamine, etc., and xanthine compounds include rhodamine-B-anilinolactam, 3-diethylamino-7, Ir-benzofluorane, rhodamine (p-nitroanilino)lactam, rhodamine B ( p-chloroanilino)lactam,
λ-Dibenzylamino-t-diethylaminofluorane, 2-anilino-6-dinithylaminofluorane, no-anilino-3-methyl-6-ethylaminofluorane, 2-anilino-3-methyl-6-fuclohexylmethyl Aminofluorane 1,2-0-chloroanilino-6-
Diethylaminofluorane, 2-m-chloroanilino-
6-Dinityl minofluorane 1. ! -(3,II-'
) Chloro Ani! J/) -6-diethylaminofluorane, 2-octylamino-6-diethylaminofluorane, -1-dihexylminino-6-dinithylaminofluorane 1, l-m-trifluoromethylanilino-6-
Dinitylaminofluoran, -1-butylamino-3-chloro-6-diethylminofluoran, 2-ethoxyethylamino-3-chloro-2-diethylaminofluoran, 2-p-chloroanilino-3-methyl-6-dibutylaminofluoran , J-anilino-3-methy, etc., and indolyl phthalide compounds include 3.3-his(/
-ethyl-2-methylindol-3-yl) phthalide, 3,3-his(/-tcutyl, 2-methylindole-/, ,2-3-yl)phthalide, 3-(,2-ethoxy- t-diethylaminophenyl)-3-(/-ethyl-2-methylindol-3-yl)phthalide, 3-(,2-ethoxy-≠-dibutylaminophenyl)-3-(/-ethyl-J-methylindole -3-yl)phthalide, 3.-
(,2-amyloxy-goodiethylaminophenyl)
-3-(/-ethyl-2-methylindol-3-yl)phthalide, 3-(,2-ethoxy-goodiethylaminophenyl)-3-(/-octyl-2-methylindol-3-yl)phthalide, etc. Examples of pyridine compounds include 3-(,2-ethoxy-goodiethylaminophenyl)-3-(/-octyl-2-methylindol-3-yl, -μ or 7-azaphthalide, 3-( ，
2-ethoxy-goodiethylamine phenyl)-3-(
3-(,2-hexyloxy-
goodiethylaminophenyl)-3-(/-ethyl-2
-methylindol-3-yl)-≠ or 7-azaphthalide, 3-C2-ethoxy-≠-diethylaminophenyl)-j-(/-ethyl-2-phenylindole-3
-yl)-μ or 7-esterzaphthalide, 3-(,2-butoxy-≠-diethylaminophenyl)-3-(/-ethyl-cophenylintol-3-yl)-μ or 7
-Azaphthalide, 3-(-1ethoxy≠-diethylaminophenyl)-3-(/-tcutyl-2-phenylindol-3-yl)-≠, or 7-azaphthalide, and examples of fluorene compounds include 3', 6'-bisdiethylamino-j-diethylminospiro(inbensiffuran-7,9'-fluorene)-3'-one, 3J
, A /-bisdiethyl-7-diethyl-2-methylspiro (/, 3-benzoxazine, fluorene), 3'.

6'-bisdiethyl-7-dinithylaminosubilo(,2-hydro/,3-benzoxazine-≠,7'-
fluorene)-no-on, etc.

When these colorless dyes and electron-accepting compounds are applied to recording materials, they are used in the form of fine dispersions or fine droplets.

The recording material according to the present invention has extremely stable colored images, and this effect is remarkable in heat-sensitive recording materials.

For use with pressure sensitive paper, U.S. Patent No. 2. jO,5,1
A70, same, 2. , SOJ, ILL? / issue, same 2
゜J 03, No. III, December 3, No. 366,
Ibid., 2.7/, No. 2.307, Ibid., 2,730. ≠36
No. 2, 730, ≠37, 3703≠0
≠ No. 3. Hiro/Do,, No. 2.30, Dohiro 01003
As described in prior patents such as No. 1, the invention may take the form of a patent. Most commonly they consist 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.l137, same J, do00. ≠A method using the hydrophilic colloid glycocellation described in No. 31,
British Patent No. 8Pg7.797, 930. ≠≠3 issue, same 7g zo, 21y4 issue, same /.

Examples include the interfacial polymerization method described in US Pat. No. 0'i7/, No. 07A, 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 oils such as chlorinated paraffin; Vegetable oils such as cotton oil and castor oil; Animal oils; Mineral oils and mixtures thereof)
After dissolving it in microcapsules,
A color forming agent sheet is obtained by coating it on a support such as paper, high quality paper, plastic sheet, resin coated paper, etc.

Alternatively, an electron-accepting compound can be dispersed in a binder such as styrene-butadiene latex or polyhinyl alcohol by exposing or mixing it with other electron-accepting compounds, and can be applied to paper, plastic sheets, resin-coated materials together with the pigments described below. A developer sheet is obtained by coating a support such as paper.

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

When used in thermal paper, the electron-donating colorless dye electron-accepting compound is pulverized and dispersed in a dispersion medium to a particle size of 10 μm or less, preferably 3 μm or less.

As a dispersion medium, a water-soluble polymer aqueous solution with a concentration of about 0.3 to 70% is generally used, and dispersion is carried out using a ball mill,
This is done using a sand mill, horizontal sand mill, dryer, colloid mill, etc.

The ratio by weight of the electron-donating colorless dye to the electron-accepting compound used is preferably between /:10 and /:/, and particularly preferably between /:j and 2:3. At that time, fatty acid esteramide, acetoacetanilide, diphenylamine,
Nitrogen-containing organic compounds such as henzamide, stearamide, stearylurea, stearanilide, carbazole, etc. or 2,3-di-m-tricifthane,
O-fluorobenzoyldenylene, chlorobenzoyldenylene/
7-lumesitylene, ≠, tI'-dimethylbiphenyl, or dimethyl isophthalate, diphenyl phthalate,
Carboxylic acid esters or ether compounds such as dimethyl terephthalate, methacryloxybiphenyl, etc. 1 such as di-m-tolyloxyethane, no-benzyloxynaphthalene, /, 2-diphenoxyethane, /
, 2-his-m-tolyloxyethane, /-phenoxy-λ-p-chlorophenoxyethane, β-phenethyl-
r+fucy-p-t-phenyl, β-phenoxyeth-
t-silonisole, /-phenoxy-, 2-1)-ethylphenoxyethane, bis-β-(p-methoxyphenoxy)ethoxymethane, /-2'-methylphenoxy-
λ'-ethylphenoxyethane, /-tolyloxy-no-p-methylphenoxyethane, /, 2-diphenoxyethane, /, 4t-diphenoxybutane, binu β-(
p-ethoxyphenoxy)ethyl ether, /-phenoxy-x-p-chlorophenoxyethane, /-,2
'-Methylphenoxy-λ-q'-ethyloxyphenoxyethane, /-4''-methylphenoxy-λ-≠'-
Fluorophenoxyethane, etc. Melting point 7J'C~/30℃
You may use these compounds together. Among these, it is particularly preferable to use those having an amide bond in the molecule. These are used in finely dispersed form at the same time as a colorless dye or at the same time as an electron-accepting compound. In particular, it is preferable to disperse the colorless dye at the same time from the viewpoint of preventing fogging. The amount of these used is added at a weight ratio of 20% or more and 300% or less, particularly preferably ≠0% or more and 7.50% or less, based on the electron-accepting compound.

Additives are further added to the coating liquid thus obtained in order to satisfy various requirements.

As an example of a cooling strength agent, oil-absorbing substances such as inorganic pigments and polyurea fillers are completely dispersed in the binder to completely prevent stains on the recording head during recording. Fatty acids, metal stones, etc. are added to improve mold release properties to 16%. Therefore, in addition to colorless dyes and electron-accepting compounds that contribute to color development, pigments, waxes, antistatic agents, ultraviolet absorbers, antifoaming agents, tetraelectric agents, fluorescent dyes, surfactants such as hindered phenols, etc. Additives are applied onto the support to constitute the recording material.

Specifically, pigments such as kaolin, calcined kaolin, talc, zinc oxide, porcelain earth, calcium carbonate, aluminum hydroxide, magnesium hydroxide, calcined stone wax, silica, carbonated magfusiwaum, titanium oxide, alumina, and carbonic acid are used as pigments. Barium, sulfuric acid, mica, microballoon,
It is selected from those having a particle size of 0.7 to /jμ, such as urea-formalin filler, polyethylene/ζ□-ticle, and cellulose filler. Examples of waxes include chisel fine wax, carboxy-modified paraffin wax, cowna wax, microcrystalline wax, polyethylene wax, and higher fatty acid esters.

Examples of metal salts include polyvalent metal salts of crystalline fatty acids, such as zinc phosphate, aluminum stearate, calcium lx phosphate, and zinc oleate.

Hindered phenol (-) is preferably a phenol derivative in which at least 7 or more of the 2 or 4 positions are substituted with a branched alkyl group. Examples of preferred hindered phenols include / , / , 3-tris (2-methyl-4-hydroxy-3-tert-butylphenyl)
Butane, /, /, 3-tris(,!-ethyl≠-human-waxy-3-tert-butylphenyl)butane, /
, /, 3-tris(3゜J-di-tert-butyl-hydroxyphenyl)butane, /, /, 3-
1-Lis(2-methyl-≠-hydroxy-3-tert
-butylphenyl)bronomine, 2. ．． 2'-methylene-his (A-tert-butyl-≠-methylphenol), 2,2'-methylene/-his (4-tert-phthyl≠-ethylphenol) ≠, ≠'-butylidene-hine (,! , -tert-butyl-3-methylphenol) 4/-'-thiohis (3-menal-tert-butylphenol), β
-(≠-Hydroxy-3.!;-Di1--.2#- Butylphenyl)propionic acid ester, /
2.5-bis(β-(≠-hydroxy-3゜J-di-t
-7'tylphenyl)ethylcarbonyloxy)-3-
Examples include thiapentane. The amount of the hindered phenol compound used is preferably 7 to 200% by weight based on the electron-accepting compound, and the more preferable amount is J-! ; 0% by weight.

These are dispersed and applied in a binder.

Water-soluble binders are generally used, such as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, epichlorohydrin-modified polyamide, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, and imbutylene-maleic anhydride. Examples include acid copolymers, polyacrylic acid, polyacrylic acid amide, methylol-modified polyacrylamide, starch derivatives, casein, and gelatin. -Is there a water-resistant agent (gelling agent, cross-linking agent) used to impart water resistance to these binders? Alternatively, an emulsion of a hydrophobic polymer, specifically, a styrene-butadiene rubber latex, an acrylic resin emulsion, etc. can be added. The coating liquid is applied onto base paper, high quality paper, synthetic paper, plastic sheet or neutral paper at a rate of about 2 to 70 l/l.

Further, the coated surface layer is coated with 00.2~. It is also possible to provide a film retaining layer with a thickness of about 2 μm to increase the resistance.

When used for thermal paper, 01. S, 2. ! , 2dojza No. 7, same-iiogsda, Tokkosho, 5.2-. 20
/j, 2, etc. may be adopted.

Alternatively, operations such as preheating, humidification, or stretching of coated paper may be added prior to recording.

For example, the electrically conductive thermal paper is published in Japanese Patent Application Publication No. 1999-19-3≠≠, same!
; 0-II-DO930, etc. Generally, a coating liquid in which a conductive substance, a basic dye mainly consisting of the fluoran derivative of the present invention, 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. The electrically conductive thermal paper of the present invention is produced by forming a multilayer and applying thereon a coating liquid in which a colorless dye, an electron-accepting substance, and a binder are dispersed. Incidentally, 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-Sho, 57-/79g31°. In general, a photopolymerization initiator such as silver iodobromide, silver bromide, silver behenate, Michler's compound, benzoin derivative, benzophenone derivative, etc. and a polyfunctional polymer such as polyallyl, poly(meth)acrylate, poly(meth)acrylamide, etc. A synthetic resin wall such as polyether urethane or polyurethane is encapsulated in the capsule together with a crosslinking agent such as a colorless dye and optionally a solvent. After imagewise exposure, the colorless dye in the unexposed area is utilized and brought into contact with a color developer to be colored.

(Examples of the Invention) Examples are shown below, but the present invention is not limited thereto. Unless otherwise specified in the examples, 2≠- indicates weight %.

Thermal response is Fujitsu's high-speed facsimile FF-200.
Using 0" f, a copy of the image test chart 3 was made and the density was measured using a Macbenu R1)-ta/g type densitometer.

Electron-donating colorless dyes, noanilino-3-chloro-6-diethylminofluorane and 2-anilino-3-
An equal weight mixture of methyl-6-ethylheinamyl-aminofluora/salicylic acid as shown in Table 1.
20:! 5% polyvinyl alcohol (Kuraray PVA)
-10! ;) After being poured into an aqueous solution with stirring and sufficiently defoamed, it was fractionally processed in a sand mill (Dyno Mill Kl) to obtain an average particle size of 3 microns or more. On the other hand, a mixture of equal weights of calcium 7um carbonate and lead oxide goy
-2, sodium hexametaphosphate 0. It was used after being dispersed in a homogenizer with 10% bath g/l and 100 g/l. Each of the dispersions 1 to 1 was prepared as described above, electron-donating colorless dye dispersion, 3y1 salicylic acid conductor dispersion 102, -,! J
- Stearamide dispersion 3y1 pigment dispersion, mixed in a ratio of 22, and an emulsion of zinc stearate ≠ 1 and an aqueous solution of sodium di(2-ethylhexyl)sulfosuccinate in proportion 2! ; f/”k was added to obtain a coating liquid.

The coating solution thus obtained was applied with a wire bar to a dry coating amount of 7 y/m on high-quality paper with a basis weight of toyim, dried in a jOoC oven, calendered, and used for thermal recording. Obtain 1 material.

(Comparative Example) A heat-sensitive recording material was obtained in the same manner as in the example except that only the salicylic acid derivative was replaced with another compound.

The results are shown in Table 1. Chemical resistance is determined by impregnating two sheets of paper each with ethanol, castor oil, and diazo developer, and superimposing them on the colored side of the recording paper obtained by the above method to prevent fogging in the white area and decoloration (discoloration and fading) in the colored area. The degree of

,! 6 - From these results, it can be seen that the recording material according to the present invention exhibits extremely superior performance, with less fogging or decoloring of colored areas caused by chemicals.

Patent applicant: Fuji Photo Film Co., Ltd. -, 2 and -

Claims (1)

[Claims] A heat-sensitive recording material that utilizes color development due to contact between an electron-donating colorless dye and an electron-accepting compound, characterized in that it contains a bissalicylic acid derivative or a metal salt thereof as the electron-accepting compound.