JPS63170081A - Thermal recording material - Google Patents

Abstract

PURPOSE:To improve water-proofness, solvent-resistance, and a matching property with a thermal printing head by adding a dye subjected to a surface modification to a protective layer provided on a thermal color developing layer containing an electron acceptive compound which develops a color in reaction with a precursor of electron donative dye. CONSTITUTION:A dye with a surface modified by a silane coupling agent, a titanate coupling agent, and an aluminium coupling agent is contained in at least one out of one or more protective layers provided on a thermal color developing layer as a filler. In addition, said dye may be contained in a thermal color developing layer. As such dyes, silica, kaolin, talc and titanium oxide, each having a grain diameter of at most 10mum, should preferably be used. As a binder, water-soluble or organic solvent-soluble or moisture dispersing materials such as polyvinyl alcohol and melamine resin are used. Further, for improvement of matching property with a thermal printing head, metallic soap or wax which corresponds to 1-10% of the total weight of the protective layer may be added to the protective layer. A surfactant or an agent for imparting watergroup properties may be added to the protective layer at the time of application.

Description

Detailed Description of the Invention (Field of Application of the Invention) The present invention relates to a heat-sensitive recording material that utilizes a color reaction between a colorless or light-colored electron-donating dye precursor and an electron-accepting compound. The present invention relates to a heat-sensitive recording material that has excellent properties and solvent resistance, and has improved hendomasotting properties.

(Prior art) So-called two-component heat-sensitive recording materials that utilize a color reaction between a colorless or light-colored electron-donating dye precursor and an electron-accepting compound are disclosed in Japanese Patent Publication Nos. 45-14039 and 43-416.
It is disclosed in No. 0, etc. Two-component color-forming heat-sensitive recording materials are produced by dispersing a colorless or light-colored electron-donating dye precursor and an electron-accepting compound in the form of fine particles, and then mixing these with a binder, etc. to bind these two types of heat-reactive compounds. coated on the support in such a way that it is isolated by, while
Alternatively, records can be obtained by utilizing the coloring reaction that occurs when both are melted and brought into contact with each other by heating. These two-component color-forming heat-sensitive recording materials are: (1) - secondary color development and does not require development; (0) paper quality is similar to ordinary paper; (2) easy handling; (2) high color density; (2) heat-sensitive with various color hues; It has the advantage that recording materials can be easily made and has great utility value. For this reason,
Most commonly used as a heat-sensitive recording material. In recent years, the use of heat-sensitive recording feed has been particularly remarkable in the fields of facsimiles, recorders, and printers.

On the other hand, since these heat-sensitive recording materials are primary color-forming, they have the disadvantage that the electron-donating dye precursor and the electron-accepting compound react not only with heat but also with solvents and the like.

This is because all of these heat-sensitive recording materials are organic substances.
This is because it has high solubility in solvents, and therefore a reaction occurs in the solvent. Therefore, if it comes into contact with stationery containing solvents, such as water-based ink pens, oil-based ink pens, fluorescent pens, diazu developer, adhesives, or glues, the white background of the heat-sensitive recording material may develop color or the printed area may fade. This caused a significant loss in product value.

On the other hand, conventionally, on the heat-sensitive coloring layer,
No. 7880, JP-A-48-30437, JP-A-48-
Efforts have been made to provide a solvent-resistant protective layer, as disclosed in Japanese Patent No. 31958, but the provision of the protective layer lowers coloring sensitivity and causes problems with matching with the thermal head of a thermal recording device. The inkjet paper had insufficient properties, causing problems such as sticking and noise during recording, and the writing properties of stationery were poor, causing problems such as ink smearing.

Furthermore, since the surface strength of the coating layer is insufficient, there is a drawback that when immersed in water, the coating surface peels off, making it difficult to read and distinguish the printed portion.

(Object of the Invention) The object of the present invention is to improve the above-mentioned drawbacks of heat-sensitive recording materials, to provide excellent water resistance and solvent resistance, excellent matching properties with thermal heads, and excellent writing properties on stationery, etc. The objective is to obtain a heat-sensitive recording material.

(Structure of the Invention) The object of the present invention is to provide a heat-sensitive recording material having a heat-sensitive coloring layer containing a colorless or light-colored electron-donating dye precursor and an electron-accepting compound that reacts with the electron-donating dye precursor to develop a color. This was achieved by a heat-sensitive recording material characterized by containing a surface-modified pigment in the protective layer provided on the heat-sensitive coloring layer.

The above-mentioned surface-modified pigments are those treated with ordinary surface modifiers, but in particular, silane coupling agents,
Preferably, the surface is modified with a titanate coupling agent or an aluminum-based camping agent.

Examples of the silane coupling agent include vinyltrichlorosilane, vinyl 1-lis(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane,
Vinyl silane compounds such as γ-methacryloxypropyl 1-rimethoxysilane, β(3,4 epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyljethoxysilane Epoxysilane compounds such as N
In addition to aminosilane compounds such as -β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-phenyl-T-aminopropyltrimethoxysilane, T- Mercaptopropyltrimethoxysilane, γ-
Examples include reactive silane compounds such as chloropropyltrimethoxysilane.

Examples of anti-knobbling agents include isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophophe-1) titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, and tetraoctyl tris (dioctyl pyrophore-1) titanate. Decyl phosphene 1-) titanate, Te 1-(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl)phosphate titanate 1-,bis(dioctylpyrophosphate)oxyacetate titanate,bis(dioctylpyrophosphate) phosphate) ethylene titanate, etc.

Examples of aluminum-based camping agents include acetalkoxyaluminum diisopropylate.

Surface modification of the pigment with these surface treatment agents is carried out by spraying the stirred pigment with a coupling agent solution of an optimum concentration prepared by dissolving the surface treatment agent in a suitable solvent. It is also fully possible to use a commercially available coupling agent solution. The treatment can also be carried out by adding a camping agent directly to the pigment dispersion.

The amount of the silane coupling agent, thicnate coupling agent, and aluminum coupling agent used is 0.00% relative to the pigment.
It is preferably 1 to 10 wt%, particularly preferably 0.1 to 54%. Outside this range, the effect of modification will not be apparent, which is not preferable. It is also possible to use commercially available pigments that have been subjected to silane coupling treatment as they are.

The pigment whose surface is modified by these surface treatment agents is contained as a filler in at least one of the protective layers provided on the thermosensitive coloring layer, and is also contained in the thermosensitive coloring layer in addition to this. It's okay if it's done. Examples of such pigments include zinc oxide, titanium oxide, magnesium oxide, alumina, calcium carbonate, aluminum hydroxide, magnesium hydroxide, barium sulfate, lithopone, talc, waxite, kaolin, silica, and amorphous pigments. In addition to inorganic pigments such as silica and colloidal silica, organic pigments such as urea-formalin resin and styrene-maleic acid resin copolymer are included, and silica, kaolin, talc, and titanium oxide are particularly preferred.

These pigments are used in the form of fine powder, preferably having a particle size of 10 μm or less. Further, a combination of a surface-modified pigment and an unmodified pigment may be used.

In this case, the proportion of surface-modified pigment in the total pigment is 104
% or more.

In the present invention, a pigment treated with a silane coupling agent, a thicnate coupling agent, an aluminum coupling agent, etc. is used by adding it to the following binder. Binders used include polyvinyl alcohol, modified polyvinyl alcohol, starch, modified starch, gelatin, cellulose derivatives, casein, alginic acid, polyacrylamide, polymethacrylamide, polyhinylpyrrolidone, polyvinyl methyl ether, polyester, polystyrene, Hinyl acetate, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, styrene/butadiene copolymer, styrene/butadiene/acrylic copolymer, styrene/maleic anhydride copolymer, isobutylene/maleic anhydride copolymer, A water-soluble, organic solvent-soluble or water-dispersible binder such as urea-formalin resin, phenol resin, or melamine resin is used.

In the present invention, the total weight of pigments that have been surface-modified with a silane coupling agent, thicnate coupling agent, aluminum coupling agent, etc. and unmodified pigments is 0.5 to 5% of the total weight of the binder. The amount added is preferably twice as much, particularly preferably 0.5 to 3.5 times.

In addition, metal soap or wax may be added to the protective layer in order to improve the matching property with the thermal head.

As the metal soap, higher fatty acid metal salts are used, and emulsions of zinc stearate, calcium stearate, aluminum stearate, etc. are used, and zinc stearate is particularly preferred. The amount added is 0.0% of the total weight of the protective layer.
5 to 20% is preferred, particularly 1 to 10%. Waxes include paraffin wax, microcrystalline wax, carnahawasox, methylol aeroamide, stearic acid amide, polyethylene wax,
Emulsions such as polystyrene wax are used, and the amount added is preferably 1 to 20%, particularly preferably 1 to 10%, based on the total weight of the protective layer.

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 surfactants, sulfosuccinic acid alkali metal salts,
A fluorine-containing surfactant or the like is used. Specifically, di(2-ethylhexyl)sulfosuccinic acid, di(n-
Examples include sodium salts such as hexyl) sulfosuccinic acid, ammonia J salts, etc., but most anionic surfactants are effective.

In the present invention, in order to improve the water resistance of the protective layer, an agent commonly used as a water resistance agent for a binder may be added. Specific examples include water-soluble initial condensation resins such as N-methylol urea, N-methylol melamine, urea-formalin, melamine-polmarin, -. dialdehyde compound,
Inorganic crosslinking agents such as boric acid and borax, polyacrylic acid, methyl vinyl ether-maleic acid copolymer, isobutylene
Examples include heat-treated blends such as maleic anhydride copolymers, metal oxides, polyvalent metal carboxylic acids, chromium alum, isocyanates, colloidal silica, epoxy resins, methylol urea, urethane compounds, and polymers thereof. The amount of these waterproofing agents used is preferably 0.5 to 30 wt% based on the total weight of the binder used in the protective layer of the present invention.

Examples of the colorless or light-colored electron-donating dye precursor used in the present invention include triphenylmethanemethanetuclide compounds, fluoran compounds, phenothiazine compounds, indolylphthalide compounds, leucoauramine compounds, and rhodamine lactams. Examples include triphenylmethane-based compounds, triazene-based compounds, spiropyran-based compounds, and the like.

Specific examples of phthalide compounds are given in U.S. Patent Reissue No. 23024, U.S. Patent Specifications No. 3491111, U.S. Patent No. 3491112, U.S. Patent No. 3491116, and U.S. Patent No. 3509174, and specific examples of fluorane compounds are as follows: US Pat. No. 3,624,107, US Pat. No. 3,627,787,
Same No. 3641011, Same No. 3462828, Same No. 3
No. 681390, No. 3920510, and No. 39
No. 59571, specific examples of spiropyran compounds are given in U.S. Patent No. 3971808, and specific examples of pyridine and pyrazine compounds are given in U.S. Patent No. 3775.
No. 424, US Pat. No. 3,853,869, and US Pat. No. 4,246,318.

Some examples of these include 3,3-bis(p-dimethylaminophenyl) as a triallylmethane compound.
-6-dimethylaminophthalide (i.e. crystal violet lactone), 3゜3-bis(p-dimethylaminophenyl)phthalide, 3-(p-dimethylaminophenyl)-3-(l,3-dimethylindole-3 −il)
Phthalide, 3-(p-dimethylaminophenyl)-3-
(2-methylindol-3-yl) phthalide, etc. Diphenylmethane compounds include 4,4'-bis-
Dimethylaminobenzhydrin henzyl ether, N-
There are halophenyl-leucoolamine, N-2,4,54-lichlorophenylleucoolamine, etc., and xanthine compounds include rhodamine-B-anilinolactam, rhodamine (p-nitrino)lactam,
-diethylamino-7,8-benzofluorane, rhodamine (p-nitroanilino)lactam, rhodamine B
(p-chloroanilinolactam), 2-anilino-3-
Methyl-6-dimethylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-ethylaminofluorane, 2-anilino-3-methyl-6-N-methyl-
N-(iso-propyl)aminofluorane, 2-anilino-3-methyl-6-N-methyl-N-pentylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-cyclohexylamino Fluoran, 2-anilino-3-methyl-6-dinithylaminofluoran, 2
-anilino-3-chloro-6-dimethylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N-
Isoamylaminofluorane, 2-anilino-3-methyl-6-N-methyl-N-isoamylaminofluorane, 2-anilino-3-chloro-6-dinithylaminofluorane, 2-anilino-3-chloro- 6-N-methyl-
N-ethylaminofluorane, 2-anilino-3-chloro-6-N-methyl-N-(iso-propyl)aminofluorane, 2-anilino-3-chloro-6-N-methyl-N-pentylamino Fluorane, 2-anilino-3
-chloro-6-N-methyl-N-cyclohexylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N-pentylaminofluorane, 2-anilino-3
-chloro-6-N-ethyl-N=pentylaminofluorane, 2-(p-methylanilino)-3-methyl-6-
Dimethylaminofluorane, 2-(p-methylanilino)-3-methyl-6-dinithylaminofluorane, 2
-(p-methylanilino)-3-methyl-6-N-methyl-N-ethylaminofluorane, 2-(p-methylanilino)-3-methyl-6-N-methyl-N-(is
o-propyl)aminofluorane, 2-(p-methylanilino)-3-methyl-6-N-methyl-N-pentylaminofluorane, 2-(p-methylanilino)-3-
Methyl-6-N-methyl-N-cyclohexylaminofluorane, 2-(p-methylanilino)-3-methyl-
6-N-ethyl-N-pentylaminofluorane, 2-
(p-methylanilino)-3-chloro-6-dimethylaminofluorane, 2-(p-methylanilino)-3-chloro-6-dinithylaminofluorane, 2-(p-methylanilino)-3-chloro- 6-N-methyl-N-ethylaminofluorane, 2-(p-methylanilino)-3
-chloro-6-N-methyl-N-(iso-propyl)
Aminofluorane, 2-(p-methylanilino)-3-
Chloro-6-N-methyl-N-cyclohexylaminofluorane, 2-(p-methylanilino)-3-chloro-
6-N-methyl-N-pentylaminofluorane, 2-
(p-methylanilino)-3-chloro-6-N-ethyl-N-pentylaminofluorane, 2-anilino-3-
Methyl-6-N-methyl-N-furylmethylaminofluorane, 2-anilito-3-ethyl-6-N-methyl-
N-furylmethylaminofluorane, etc., and indolylphthalide compounds include 3,3-bis(1-ethyl-2-methylindol-3-yl)phthalide, 3,
3-bis(l-octyl-2-methylindole-3-
yl)phthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3-(2-ethoxy-4-yl)
dibutylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3-(2-amyloxy-4-diethylaminophenyl)-3-(L-
ethyl-2-methylindol-3-yl)phthalide,
3-(2-ethoxy-4-diethylaminophenyl)-
Examples of pyridine compounds include 3-(1-octyl-2-methylindol-3-yl)phthalide, and 3-(2-ethoxy-4-yl).
diethylaminophenyl)-:1-(1-octyl-2
-methylindol-3-yl, -4 or 7-azaphthalide, 3-(2-ethoxy-4-diethylaminophenyl)-,3-(1-ethyl-2-methylindole-3
-yl)-4 or 7-azaphthalide, 3-(2-hexyloxy-4-diethylaminophenyl)-3-(
1-ethyl-2-methylindol-3-yl)-4 or 7-azaphthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-phenylindol-3-yl)- 4 or 7-azaphthalide, 3
-(2-butoxy-4-diethylaminophenyl)-3
-(1-ethyl-2-phenylindol-3-yl)
-4 or 7-azaphthalide, 3-(2-ethoxy-4-
diethylaminophenyl) -3-(1-octyl-2
-phenylindol-3-yl)-4 or 7-azaphthalide, and examples of fluorene compounds include 3'',6'-bisdiethylamino-5-diethylaminospiro(isobencyfufuran-1,9'-fluorene). -3'-on, 3', 6
'-bisdiethylamino-7-diethylamino-2-methylspiro (1゜3-benzoxazine-4,9'-fluorene), 3',6'-bisdiethylamino-7-diethylaminospiro (2-hydro-1,3- Benzoxazine-4,9'-fluorene)-2-one, etc.
These may be used alone, but two or more may be used in combination for tone adjustment and prevention of fading of colored images.

The electron-accepting compound used in the present invention has the general formula (1
) A salicylic acid derivative or a metal salt thereof having a substituent group is preferred.

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

In addition, an alkyl group and an alkoxy group represent a saturated or unsaturated alkyloxy group, an alkyl group, or a cycloalkyl group, and these include an aryl group, an alkoxy group, an aryloxy group, a halogen atom, an acylamino group, an aminocarbonyl group, or a cyano group. Aryl groups may have substituents such as phenyl groups, naphthyl groups, or heteroaromatic ring groups, and these include alkyl groups, alkoxy groups, aryloxy groups, halogen atoms, nitro groups, and cyano groups. , substituted carbamoyl group, substituted sulfamoyl group, substituted amino group, substituted oxycarbonyl group, substituted oxysulfonyl group, thioalkoxy group, arylsulfonyl group,
Alternatively, it may have a substituent such as a phenyl group.

Among the substituents represented by R in the above formula, carbon atoms 1 to 2
2 is preferably an alkyl group or an alkoxy group, and among the substituents represented by X, a hydrogen atom and a carbon atom number of 1 to 22
An alkyl group, an alkoxy group having 1 to 20 carbon atoms, a chlorine atom, and a fluorine atom are preferred, and among the metal atoms represented by M, zinc, aluminum, magnesium, and calcium are preferred.

Among the alkoxy groups represented by R, the number of carbon atoms is 6 to 2
Particularly preferred are an unsubstituted alkoxy group having 0, an aryl-substituted alkoxy group having 7 to 20 carbon atoms, an aryloxy-substituted alkoxy group having 7 to 20 carbon atoms, and an alkoxy-substituted alkoxy group having 6 to 20 carbon atoms vi.

From the viewpoint of water insolubility, the salicylic acid derivative according to the present invention preferably has a total number of carbon atoms of 13 or more, particularly preferably 16 or more. Further, from the viewpoint of chemical resistance, a compound having a solubility in ethanol of 10 or less is preferable.

Next, specific examples of the electron-accepting compound represented by formula (1) used in the present invention will be shown.

4-pentadecylsalicylic acid, 3,5-bis(α-methylhensyl)salicylic acid, 3,5-bis-t-octylsalicylic acid, 5-octadecylsalicylic acid 71/acid, 5-α
-(p-α-methylhensylphenyl)ethylsalicylic acid, 3-α-methylbenzyl-5-t-octylsalicylic acid, 5-tetradecylsalicylic acid, 4-hexyloxysalicylic acid, 4-cyclohexyloxysalicylic acid,
4-octyloxysalicylic acid, 4-decyloxysalicylic acid, 4-F decyloxysalicylic acid, 4-tetradecyl 1xsalicylic acid, 4-pentadecyloxysalicylic acid, 4-hexadecyloxysalicylic acid, 4-octadecyloxysalicylic acid, 4- Icosyloxysalicylic acid, 4-triacontyloxysalicylic acid, 4-oleyloxysalicylic acid, 4-β-phenethyloxysalicylic acid, 4-β-dodecyloxyethoxysalicylic acid, 4
-(12-chlorododecyl)oxysalicylic acid, 4-β
-N-stearoylaminoethoxysalicylic acid, 4-β
-N-mylinutoylaminoethoxysalicylic acid, 4-β
-Perfluorohexylethoxysalicylic acid, 4-dodecyloxy-5-chlorosalicylic acid, 4-dodecyloxy-5-methylsalicylic acid, 4-dodecyloxy-6-
Methylsalicylic acid, 4-dodecyloxy-6-phenylsalicylic acid, 4-methoxy-6-Fdecyloxysalicylic acid, 6-octadecyloxysalicylic acid, 4-pt
-octylphenyloxysalicylic acid, 4-p-dodecyloxyphenyloxysalicylic acid, 4-p-chlorophenoxy-6-methylsalicylic acid, 4-p-phenylphenoxysalicylic acid, 4-p-N-myristoylcarbamoylphenyloxysalicylic acid, 4-hensyloxy-6-dozosyloxysalicylic acid, 4-β-phenoxyethoxysalicylic acid, 4-(4-phenoxybutoxy)
Salicylic acid, 4-(6-phethoxyhexyloxy) salicylic acid, 4-(5-phenoxyamyloxy) salicylic acid, 4-(8-phenoxyoctyloxy) salicylic acid, 4-(10-phenoxydecyloxy) salicylic acid, 4- β-p-)lyloxyethoxysalicylic acid, 4-
β-m~tolyloxyethoxysalicylic acid, 4-β-p
-ethylphenoxyethoxysalicylic acid, 4-β-p-
Isoprobylphenoxyethoxysalicylic acid, 4-β-
pt-butylphenoxyethoxysalicylic acid, 4-β
-p-cyclohexylphenoxyethoxysalicylic acid,
4-β-p-octylphenoxyethoxysalicylic acid, 4-β-p-nonylphenoxyethoxysalicylic acid, 4-β-p-dodecylphenoxyethoxysalicylic acid, 4-β-p-hensylphenoxyethoxysalicylic acid , 4-(2-p-α-phenethylphenoxyethoxy)
Salicylic acid, 4-β-0-methoxyphenoxyethoxysalicylic acid, 4-β-p-cumyloxyethoxysalicylic acid, 4-β-(2,4-dimethylphenoxy)ethoxysalicylic acid, 4-β-(3,4-dimethyl phenoxy)ethoxysalicylic acid, 4-β(3,5-dimethylphenoxy)ethoxysalicylic acid, 4-β-(2,4-bis-α-phenethylphenoxy)ethoxysalicylic acid, 4
-β-p-methoxyphenoxyel-1-xysalicylic acid,
4-β-p-ethoxyphenoxyethoxysalicylic acid,
4-β-p-hensyloxyphenoxyethoxysalicylic acid, 4-β-p-1'decyloxyphenoxyethoxysalicylic acid, 4-β-p-chlorophenoxyethoxysalicylic acid, 4-β-p-phenylphenoxyethoxysalicylic acid , 4-β-p-cyclohexylphenoxyethoxysalicylic acid, 4-β-p-penzyloxylponylphenoxyethoxysalicylic acid, 4-β-p-dodecyloxycarbonylphenoxyethoxysalicylic acid, 4-β- naphthyl (2) oxyethoxysalicylic acid,
5-β-p-ethylphenoxyethoxysalicylic acid, 4
-β-phenoxyethoxy-6-methylsalicylic acid, 4
-β-phenoxyethoxy-6-chlorosalicylic acid, 4
-β-phenoxyisoprobyl ogicisalicylic acid, 4-
These include ω-p-methoxyphenoxy-3-oxa-n-pentyloxysalicylic acid, 4-ω-p-mel-=1'-diphenoxy 3-oxa-n-pentyloxysalicylic acid, and their metal salts. j1i is used alone or in combination.

The metal salt according to the present invention is preferably a salt with a divalent or trivalent metal, such as a metal selected from zinc, magnesium, barium, calcium, aluminum, tin, titanium, nickel, cobalt, manganese, iron, etc. Zinc is particularly preferred.

According to the present invention, the dispersion particle size of the salicylic acid derivative or its metal salt after atomization using a sand mill or the like is preferably 3 μm or less, preferably 2 μm or less in order to obtain color development sensitivity.

In addition to the salicylic acid derivative represented by general formula (I),
Electron-accepting compounds such as salicylic acid derivatives, phenol derivatives, phenol resins, and acid clay other than the well-known general formula (1) may be used alone, or electron-accepting compounds of the general formula (1) may be used alone.
It may be used in combination with the salicylic acid derivative shown in 1).

Some examples of these include 4-tert-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide-α-naphthol, β-naphthol, hexyl-4-hydroxybenzoate, 2,2'-dihydroxybiphenyl, 2 .2-bis(4-hydroxyphenyl)propane (bisphenol A), 4.4'-isopropylidene bis(2-methylphenol), 1.1
'-Bis(3-chloro-4-hydroxyphenyl)
cyclohexane,
t-octylphenol, 4.4'-5ec-butylidene diphenol, 4-p-methylphenylphenol,
4.4'-isopentylidenephenol, 4.4'-methylcyclohexylidene diphenol, 4,4'-dihydroxydiphenyl sulfide, 1,4-bis-(4
'-Hydroxycumyl) Hensen, 1,3-bis-(4
'-Hydroxycumyl) Hensen, 4.4'-thiobis(6-tert-butyl-3-methylphenol), 4
．． 4'-dihydroxydiphenylsulfone, hydroquinone monohensyl ether, 4-hydroquinonehensiphenone, 2.4-dihydroxyhensiphenon, polyvinylhenzylic carbonylphenol 1.2. 4.
4′-1-dihydroxyhensiphenone, 2.2′
, 4.4'-tetrahydroxyhenzophenone, 4-hy[-ro:tosifucuric acid, dimethyl-4-hydroxybenzoic acid methyl, 2. 4. 4'-)lihydroxydiphenylsulfone, ■, 5-bis-p-hydroxyphenylpenkune, 1,6-bis-p-hydroxyphenoxyhexane, tolyl 4-hydroxybenzoate, 4-hydroxybenzoic acid α-phenylbenzyl ester , phenylpropyl 4-hydroxybenzoate, phenethyl 4-hydroxybenzoate, p-chlorobenzyl 4-hydroxybenzoate, p-methoxyhensyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, 4-
Hydroxybenzoin fl! -m-chlorobenzyl ester, 4-hydroxybenzoic acid-β-phenethyl ester,
4-Hydroxy-2',4'-dimethyldiphenylsulfone, β-phenethylorseinate, cinnamylorseinate, orselic acid-〇-chlorophenoxyethyl ester, 〇-ethylphenoxyethylorseinate, 0-phenylphenoxy ethyl orcelinate,
m-Phenylphenoxyethyl orcelinate, 2.4
-dihydroxybenzoic acid-β-3'-t-butyl-4'
-Hydroxyphenoxyethyl ester, 1-t-butyl-4-p-hydroxyphenylsulfonyloxybenzene, 4-N-benzylsulfamoylphenol, 2
, 4-dihydroxybenzoic acid-β-phenoxyethyl ester, 2,4-dihydroxy-6-methylbenzoic acid hensyl ester, methyl bis-4-hydroxyphenylacetate, ditolylthiourea, 4,4゛-diacetyldiphenylthiourea, 3-phenylsalicylic acid, 3-cyclohexylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3-methyl-5-benzylsalicylic acid, 2
-Phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3.5-di(α-methylbenzyl)salicylic acid, 5-t-octylsalicylic acid, 3.5-di-t-butylsalicylic acid, 3-chloro- 5-cumylsalicylic acid, 3
-Methyl-5-t-octylsalicylic acid, 3-methyl-
5-α-methylbenzylsalicylic acid, 3-methyl-5-
Cumylsalicylic acid, 3.5-di-t-amylsalicylic acid, 3-phenyl-5-benzylsalicylic acid, 3-phenyl-5-t-octylsalicylic acid, 3-phenyl-5-
α-Methylbenzylsalicylic acid, 3,5-di-t-octylsalicylic acid, 3,5-bis(α-methylbenzyl)
Salicylic acid, 3.5-dicumylsalicylic acid, 4-methyl-5-(α-methylbenzyl)salicylic acid, 4-methyl-5-cumylsalicylic acid, 3-(α-methylhensyl)
-6-methylsalicylic acid, 3-(α-methylhensyl)
-6-phenylsalicylic acid, 3-triphenylmethylsalicylic acid, 3-diphenylmethylsalicylic acid, 4-n-
Dodecylsalicylic acid, 4-t-dodecylsalicylic acid, 4
-n-dodecylsalicylic acid, 4-n-pentadecylsalicylic acid, 4-n-heptadecylsalicylic acid, 5-(1,
3-diphenylbutyl)-salicylic acid, 5-n-octadecylsalicylic acid, 5-dodecylsulfonylsalicylic acid, 5°-dodecylsulfosalicylic acid, 3-methyl-5-
Examples include dodecylsulfosalicylic acid.

The electron-accepting compound is 50 to 8 of the electron-donating dye precursor.
It is preferable to use 00% by weight, more preferably 100 to 500% by weight.

The above electron-accepting compounds may be used alone or in combination of two or more.

When the present invention is used in a heat-sensitive recording material, a heat-fusible substance can be contained in the heat-sensitive coloring layer in order to improve the heat responsiveness of the material.

As an example of a preferable thermofusible substance, the following general formula (II)
Examples include compounds represented by (VI).

Rs N HCON Hz (V)
Rb CON HR, (■) In the formula, R1 to R4 are respectively a phenyl group, a Henzyl group,
and a lower alkyl or halogen substituted product thereof, R5 and R6 each represent an alkyl group having 12 to 24 carbon atoms, and R7 represents hydrogen or a phenyl group.

In addition, when the phenyl group or benzyl group represented by R3-R4 in general formulas (II) to (VI) is substituted with a lower alkyl group, the number of carbon atoms is 1 or more and 8 or less, preferably 1 or more and 3 or less. be. When substituted with a halogen atom, fluorine is preferred. Also, the formula (I
In V), R4' represents hydrogen or a hydroxyl group.

(■) In the formula, R8 represents a divalent group, preferably an alkylene group, an alkylene group having a carbonyl group, an alkylene group having a halogen atom, an alkylene group having an unsaturated bond, more preferably an alkylene group, an ether bond. Indicates an alkylene group with

In addition, x, y, z, x', Y', and Z' may be the same or different and represent a hydrogen atom, a halogen atom, an alkyloxycarbonyl group, an aralkyloxycarbonyl group,
A represents O or S.

The compounds of the general formulas (II) to (■) have a melting point of 7°C.
The melting point is preferably 80°C or higher and 130°C or lower, and more preferably 80°C or higher and 130°C or lower. Specifically, benzyl p-benzyloxybenzoate, β-naphthylbenzyl ether, stearic acid amide, palmitic acid amide, N-phenylniaric acid amide, N-stearylurea, β-naphthoic acid phenyl ester, 1- Hydroxy-2-naphthoic acid phenyl ester, β-naphthol ether, β-naphthol (p-methylbenzyl) ether, α-naphthylbenzyl ether, 1,4-
Butanediol-p-methylphenyl ether, 1.4
-Propanediol-p-methylphenyl ether, L
4-butanediol-p-isopropylphenyl ether, 1,4-butanediol-p-t-octylphenyl ether, 2-phenoxy 1-p-)lyluoxyene, 1-phenoxy-2-(4-ethylphenoxy ) ethane, -phenoxy 2-(4-chlorophenoxy)ethane, 1,4-butanediol phenyl ether, diethylene glycol-bis(4-methoxy-phenyl) ether, and the like.

The thermofusible substance may be used alone or in combination, and in order to obtain sufficient thermal responsiveness, it is preferably used in an amount of 10 to 200% by weight, more preferably from 10 to 200% by weight, based on the electron accepting compound. The amount used is 20-150% by weight.

A water-soluble binder is added to the recording layer of the recording material of the present invention. These binders are preferably compounds that dissolve 5% by weight or more in water at 25°C, and specific examples include polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, starch i (including i starch), gelatin, Gum arabic casein, styrene-maleic anhydride copolymer hydrolyzate, ethylene-maleic anhydride copolymer hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, carboxy-modified polyvinyl alcohol, polyacrylamide, vinyl acetate and saponified copolymers of polyacrylic acid and polyacrylic acid. These binders may be used as electron-donating dye precursors, electron-accepting compounds, thermofusible substances, and dispersants for finely dispersing compounds of formula (1) according to the invention.

Furthermore, if necessary, the recording layer of the heat-sensitive recording material of the present invention may contain pigments, water-insoluble binders, metal soaps, waxes, surfactants, antistatic agents, ultraviolet inhibitors, antifoaming agents, conductive agents, fluorescent Add dye etc.

As the pigment, calcium carbonate, barium sulfate, lithopone, talc, waxite, kaolin, silica, amorphous silica, etc. are used, but light calcium carbonate, kaolin, surface-treated amorphous silica, and aluminum hydroxide are preferable. .

As the water-insoluble binder, synthetic rubber latex or synthetic resin emulsion is generally used, such as styrene-butadiene rubber latex, acryloni-F lylubutadiene rubber latex, methyl acrylate-butadiene rubber latex, vinyl acetate emulsion, etc. . In order to prevent fogging of the heat-sensitive recording material, the amount of surfactant used in the rubber latex or emulsion should be as small as possible, and so-called soap-free rubber latex or emulsion is preferred.

As the metal soap, higher fatty acid metal salts are used, such as emulsions of zinc stearate, calcium stearate, and aluminum stearate.

As the wax, emulsions such as paraffin wax, microcrystalline wax, carnauba wax, methylolstearamide, polyethylene wax, and polystyrene wax are used.

As the surfactant, sulfosuccinic acid-based alkali metal salts, fluorine-containing surfactants, etc. are used.

In the heat-sensitive recording material according to the present invention, it is preferable that the heat-sensitive coloring layer contains a compound that prevents color fading in order to prevent the printed image from fading and to harden the generated image.

As the anti-fading agent, phenol derivatives, especially hindered phenol compounds, are effective, and at least 2 or 6
Phenol derivatives in which one or more of the positions are substituted with a branched alkyl group are preferred.

Examples of preferable anti-fading agents include the following general formulas (■) to (
Examples include compounds represented by XI).

(In the formula, R5 is a branched alkyl group having 3 to 8 carbon atoms, R2 is hydrogen or a branched alkyl group having 3 to 8 carbon atoms, R3 is hydrogen or an alkyl group having 1 to 3 carbon atoms, and R4 is a branched alkyl group having 3 to 8 carbon atoms. Hydrogen or an alkyl group having 1 to 8 carbon atoms, R9, Rb, and R7 are hydrogen or an alkyl group having 1 to 3 carbon atoms, and R8 is hydrogen or an alkyl group having 1 to 8 carbon atoms. represents a branched alkyl group having 3 to 8 carbon atoms, R2 and R6 represent an alkyl group having 1 to 8 carbon atoms, and X represents s, s, so2, S2, ÷C+T, pentylene group or cyclohexylene group represents, n
is an integer of O to 3, and R5 and R6 represent hydrogen or an alkyl group having 1 to 8 carbon atoms. ) (In the formula, R1 and R4 are branched alkyl groups having 3 to 8 carbon atoms, and R2, R3, R6, and R6 are hydrogen or an alkyl group having 1 to 8 carbon atoms.

Y is represented by S, O, SO2, S2, ÷C-)--1,
m is an integer of θ to 3; R7 and R8 represent hydrogen, an alkyl group having 1 to 8 carbon atoms, or a cyclic pentamethylene group formed by bonding R7 and R8; ) (In the formula, R4 and R2 are branched alkyl groups having 3 to 8 carbon atoms, Z is -NH-2O(CHz)T (where n represents an integer of 1 to 5), and i is 1 represents an integer of ~4.However, when i=1, W represents an alkyl group having 1 to 18 carbon atoms, and when i-2, W represents S, 0l-r-c → , R4 represents hydrogen or an alkyl group having 1 to 8 carbon atoms, and j represents an integer of 0 to 8. represents an alkyl group), and when i-4, representative examples of phenol derivatives represented by the above general formulas (■) to OG) are shown.

(A> As a phenol derivative represented by the general formula (■), 1.1.3-1-lis(2-methyl-4-hydroxy-
5-tert-butylphenyl)butane, ■.

1.3-tris(2-ethyl-4-hydroxy-5-t
ert-butylphenyl)butane, 1. 1. 3-tris(3,5-di-tert-butyl-4-hydroxyphenyl)butane, 1,1.31lis(2-methyl-4
-hydroxy-5-tert-butylphenyl)propane and the like.

(B) As the phenol derivative represented by the general formula (IX), 2,2'-methylene-bis(6-tert-butyl-4
-methylphenol), 2,2'-methylene-bis(6
-tert-butyl-4-ethylphenol).

(C) As the phenol derivative represented by the general formula (X), 4,4'-butylidene-bis(5-tert-butyl-
3-methylphenol) 4,4'-thio-bis(3-methyl-5-tert-butylphenol).

(D) Examples of the phenol derivative represented by the general formula (Kari) include the following.

The usage amount of the phenol compound represented by the general formulas (■) to (XI) is preferably 1 to 200% by weight based on the electron-accepting compound, and the more preferred usage amount is 5% by weight.
~50% by weight.

In the present invention, a heat-sensitive coloring layer made of a combination of the above-mentioned compounds is formed on a support, and a protective layer containing a pigment surface-treated with a silane coupling agent, a thicnate coupling agent, or an aluminum-based camping agent. The protective layer may have two or more layers. In addition, a pigment surface-modified with a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, etc. may also be added to the heat-sensitive coloring layer.

The product of the present invention improves the surface strength of the coating film by providing a protective layer containing a pigment surface-treated with a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, etc. on the heat-sensitive coloring layer, and improves the surface strength of the coating film. Not only does it exhibit excellent durability against solvents and solvents, it also has significantly improved hendomasotching properties.

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

(Examples 1 to 10) Electron-donating dye precursor 2-anilino-3-methyl-6-
20 g of each of N-methyl-N-microhexylaminofluorane, the electron-accepting compound 4-β-p-methoxyphenoxyethoxysalicylic acid, and the heat-fusible substance stearic acid amide were mixed with 100 g of a 5% polyvinyl alcohol aqueous solution in a ball mill overnight. The particles were dispersed to have a volume average particle size of 3 μm or less. The pigment was used by dispersing 80 g of calcium carbonate with 160 g of a 0.5% solution of sodium hexametaphosphate using a homogenizer.

Each of the dispersions prepared as described above was mixed in a ratio of 5 g of the electron-donating dye precursor dispersion, the electron-accepting compound dispersion Log, 5 g of the thermofusible substance dispersion, and 22 g of the pigment dispersion, and then 21% Zinc Stearate Emulsion 3
g and 5 g of a 2% aqueous solution of sodium di(2-ethylhexyl)-sulfosuccinate.
It was coated on a 0 g/m high-quality paper with a wire bar to a dry coating weight of 7 g/m, and dried in an oven at 50° C. to obtain a heat-sensitive coloring layer.

100g of binder solution on the thermosensitive coloring layer obtained by the above method,
A dispersion consisting of 15 g of a pigment dispersion, 20 g of a 5% glyoxal solution, 4 g of a 21% zinc stearate emulsion, and 2 g of a 2% solution of sodium di(2-ethylhexyl)sulfosuccinate was coated with a wire bar so that the dry coating amount was 2 g/m'. After drying in an oven at 50° C., the material was treated with a super calender so that the Bekk smoothness of the surface was 800 seconds or more to obtain a heat-sensitive recording material according to the present invention. The binder, pigment and surface modifier in the above dispersion are
Shown in the table. The modified pigment was dispersed using the same method as the dispersion of the pigment contained in the heat-sensitive coloring layer.

(Examples 11 to 20) Thermosensitive coloring layers were obtained in the same manner as Examples 1 to 10, except that phenoxyacetobenzylamine was used instead of stearamide as the thermofusible substance contained in the thermosensitive coloring layer. .

100g of binder solution on the thermosensitive coloring layer obtained by the above method,
A dispersion consisting of 15 g of pigment dispersion, 20 g of 5% glyoxal solution, 4 g of 21% zinc stearate emulsion, 2 g of 21% sodium di(2-ethylhexyl)sulfosuccinate solution was mixed with a wire bar so that the dry coating amount was 2 g/m. After coating and drying in the open at 50° C., the material was treated with a super calender so that the Bekk smoothness of the surface was 800 seconds or more to obtain a heat-sensitive recording material according to the present invention.

The binder, pigment and surface modifier in the above dispersion are shown in Table 2. The modified pigment was dispersed using the same method as the dispersion of the pigment contained in the heat-sensitive coloring layer.

(Comparative Example) A thermosensitive coloring layer was obtained in the same manner as in Examples (1 to 10). The composition of the protective layer is the same as in Example (1-10) except for the combination of binder and pigment. Table 3 shows the combinations of binders and pigments in comparative examples.

Table 3 The dry weight of the protective layer dispersion thus obtained was 2 g.
/ m with a wire bar and dried in the open at 50'C, treated with a super calender so that the surface smoothness was 80 (1 second or less) and compared with the comparative example (
Thermosensitive recording materials 1 to 4) were obtained.

The coloring temperature was measured using a Matsushita Electric Transmission 0 Kiku high-speed facsimile model UF-2, by copying the Image Electronics Engineers Test Chart No. 3, and measuring its density with a Macbeth Co., Ltd. RD-918 model densitometer.

On the other hand, to evaluate the scab resistance (chemical resistance), a filter paper was impregnated with ethanol, toluene, and methyl cellosolve, and the resulting paper was superimposed on the colored surface of the heat-sensitive recording material to evaluate the degree of fog. The facsimile runnability was evaluated by using a Matsushita Electric Transmission High Speed Facsimile Model UF-2 and continuously copying over 100 copies of the Institute of Image Electronics Engineers Test Charts 111o and 2.

Suitability for stationery was evaluated by evaluating ink stains and drying of water-based ink pens and oil-based ink pens in printed areas and white background areas of the coloring surface of the heat-sensitive recording material. In addition, the storage stability of the printed image was visually evaluated.

Regarding water resistance, the heat-sensitive recording material was immersed in distilled water for 24 hours, then taken out, the coated surface was rubbed with a finger, and peeling of the coated layer was visually evaluated on a five-point scale.

Claims (2)

[Claims] (1) A thermosensitive recording material having on a support a thermosensitive coloring layer containing a colorless or light-colored electron-donating dye precursor and an electron-accepting compound that reacts with the electron-donating dye precursor to develop color. A heat-sensitive recording material characterized by containing a surface-modified pigment in a protective layer provided on the layer. (2) The heat-sensitive recording material according to claim 1, wherein the pigment is a pigment treated with a silane coupling agent, a titanate coupling agent, or an aluminum coupling agent.