JPH04329182A - Thermosensitive recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermosensitive recording medium which demonstrates long preservative stability of a recorded image and the minimized. occurrence of a background fog by allowing a phosphoric acid derivative expressed by a specific formula or its alkali metal salt to be added to a thermosensitive recording medium using a color-development reaction between a colorless or pale basic dye and a color developer. CONSTITUTION:A phosphoric acid derivative expressed by formula I or at least, one type of its alkali metal salt is added to a thermosensitive recording medium using a color development reaction between a colorless or pale basic dye and a color development agent. In the formula, R1 to R10 show a hydrogen atom, an alkyl group, an aralkyl group, an aryl group an alkoxy group, an aralkyloxy group, an aryloxy group, a hydroxy group or a halogen atom. In addition, R1 and R2, R2 and R3, R6 and R7 and R7 and R8 can be bonded together respectively to form a ring. Then this phosphoric acid derivative or its alkali metal salt is added to a recording layer. Subsequently, a thermosensitive recording medium having the long preservation stability of a recorded image is obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording medium, and more particularly to a heat-sensitive recording medium that has excellent storage stability of recorded images and extremely little background fog.

0002

[Prior Art] Conventionally, heat-sensitive recording materials are well known, which utilize the reaction between a colorless or light-colored basic dye and a coloring agent, and obtain a recorded image by causing the two coloring substances to react with heat. . However, such heat-sensitive recording materials generally have the disadvantage that the storage stability of the recorded images is not sufficient and the colors fade over time. In particular, if a recorded heat-sensitive recording material is stored under high humidity or high temperature conditions, the recorded image will disappear within a relatively short period of time, so there is a strong demand for improvement.

[0003] For this reason, heat-sensitive recording materials to which various storage improvers are added have been proposed for the purpose of improving the storage stability of recorded images. Due to the drawbacks associated with this method, satisfactory results have not always been obtained.

0004

[Problems to be Solved by the Invention] In view of the current situation, the present inventor has conducted intensive studies on storage improvers and found that when a specific phosphoric acid derivative or its alkali metal salt is used, storage under high temperature or high humidity conditions is difficult. The present inventors have discovered that a heat-sensitive recording material with excellent storage stability of recorded images can be obtained without any new drawbacks such as the tendency to cause background fogging even when the recording material is heated, and has completed the present invention.

[0005]

[Means for Solving the Problems] The present invention provides a heat-sensitive recording material that utilizes a coloring reaction between a colorless or light-colored basic dye and a coloring agent. This is a heat-sensitive recording material characterized by containing at least one kind of a derivative or an alkali metal salt thereof.

[0006]

[Chemical formula 1]

[In the formula, R1 to R10 each represent a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, an alkoxyl group, an aralkyloxy group, an aryloxy group, a hydroxyl group, or a halogen atom. In addition, R1 and R2, R2 and R3, R6 and R7, R7 and R
8 may be bonded to each other to form a ring. ]

[0008]

[Function] The heat-sensitive recording material of the present invention uses a phosphoric acid derivative represented by the above general formula [Chemical formula 1] or an alkali metal salt thereof as a preservability improver. Specific examples of such phosphoric acid derivatives are as follows. For example, the following can be exemplified. diphenyl phosphate, bis(2-methylphenyl) phosphate, bis(3-methylphenyl) phosphate,
Bis(4-methylphenyl)phosphate, bis(4-
Ethylphenyl) phosphate, bis(4-isopropylphenyl) phosphate, bis(4-tert-butylphenyl) phosphate, bis(4-nonylphenyl) phosphate, bis(2,4-di-tert-butylphenyl) phosphate, bis (2,4,6-tri-t
ert-butylphenyl) phosphate, bis(4-α
, α-dimethylbenzylphenyl) phosphate, bis(2-α,α-dimethylbenzylphenyl) phosphate, bis(4-α-methylbenzylphenyl) phosphate, bis(2,4-di-α-methylbenzylphenyl) phosphate , bis(4-phenylphenyl) phosphate, bis(2-phenylphenyl) phosphate,
Bis(4-methoxyphenyl)phosphate, bis(3
-methoxyphenyl) phosphate, bis(2-methoxyphenyl) phosphate, bis(4-isopropyloxyphenyl) phosphate, bis[4-(2-ethylhexyloxy)phenyl]phosphate, bis(2,
4-dimethoxyphenyl) phosphate, bis(4-benzyloxyphenyl) phosphate, bis(4-phenoxyphenyl) phosphate, bis(4-hydroxyphenyl) phosphate, bis(4-chlorophenyl)
Phosphate, bis(2-chlorophenyl) phosphate, bis(3-chlorophenyl) phosphate, bis(
4-bromophenyl) phosphate, bis(2,4-dichlorophenyl) phosphate, bis(2,4,6-trichlorophenyl) phosphate, bis(3-methyl-
6-tert-butylphenyl) phosphate, bis(
4-Methyl-2-tert-butylphenyl) phosphate, bis(2-cyclohexylphenyl) phosphate, bis(4-α,α-dimethylbenzyl-2-cyclohexylphenyl) phosphate, bis(4-methyl-
2-α,α-dimethylbenzylphenyl) phosphate, phenyl-4-tert-butylphenyl phosphate, 4-tert-butylphenyl-2,4-di-te
rt-butylphenyl phosphate and the like. Of course, it is not limited to these, and it is also possible to use two or more types in combination as necessary.

[0009] Examples of alkali metals that form salts with the above phosphoric acid derivatives include sodium, potassium, rubidium, cesium, etc. If necessary, complex salts of two or more metals can be formed. . The amount of these phosphoric acid derivatives or their alkali metal salts to be used is not necessarily limited;
It is desirable to adjust the amount to about 5 to 500 parts by weight, preferably about 10 to 200 parts by weight.

In the present invention, the general formula [Formula 1]
By using in combination a polyvalent metal salt of a phosphoric acid derivative represented by, the desired effect can be further enhanced. Examples of metals constituting such polyvalent metal salts include zinc, magnesium, barium, calcium, aluminum, lead, titanium, nickel, cobalt, manganese, iron, etc. If necessary, composites of two or more metals may be used. It is also possible to use salt. As a method for preparing a polyvalent metal salt of a phosphoric acid derivative, for example, (1) reacting an alkali metal salt of a phosphoric acid derivative with a salt containing a polyvalent metal as described above in a polar solvent to completely or partially salt the phosphoric acid derivative; (2) Complete or partial salt exchange by subjecting a phosphoric acid derivative or its alkali metal salt to dry or wet pulverization treatment with a compound containing a polyvalent metal as described below. Examples of the compounds used in the above method (■) include oxides, hydroxides, and sulfides of metals selected from zinc, magnesium, barium, calcium, aluminum, lead, titanium, nickel, cobalt, manganese, iron, etc. Halides, carbonates, phosphates, silicates, sulfates, nitrates, aluminates, or halogen complex salts, etc. More specifically, for example, zinc oxide, zinc hydroxide, zinc sulfide, zinc chloride, zinc carbonate , zinc phosphate, zinc silicate, zinc sulfate, zinc nitrate, zinc aluminate, magnesium oxide, magnesium hydroxide, magnesium sulfide, magnesium chloride, magnesium carbonate, magnesium phosphate, magnesium silicate, magnesium sulfate, magnesium nitrate, aluminium. magnesium acid, barium chloride, barium carbonate, barium sulfate, calcium oxide, calcium hydroxide, calcium chloride, calcium carbonate, calcium silicate, aluminum oxide, aluminum hydroxide, aluminum phosphate,
Inorganic metal compounds such as aluminum silicate and titanium oxide;
Silica surface-treated with a substance containing polyvalent metal ions such as zinc, magnesium, barium, calcium, and aluminum; examples include organometallic compounds such as zinc stearate, magnesium stearate, barium stearate, calcium stearate, and aluminum stearate. can.

[0011] The amount used when a polyvalent metal salt of a phosphoric acid derivative is used in combination is not necessarily limited, but it is about 5 to 1000 parts by weight per 100 parts by weight of the phosphoric acid derivative or its alkali metal salt. , preferably 20~
It is desirable to use about 500 parts by weight of the polyvalent metal salt. In the heat-sensitive recording material of the present invention, the phosphoric acid derivative or its alkali metal salt, or its polyvalent metal salt, as described above, is present not only in the recording layer but also in the intermediate layer provided between the recording layer and the support. Although it can be added to the overcoat layer provided on the recording layer, it is preferable to include it in the recording layer from the viewpoint of effectiveness.

In the present invention, various known dyes can be used as the colorless or light-colored basic dye constituting the heat-sensitive recording layer, including the following. 3,3-bis(
p-dimethylaminophenyl)-6-dimethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)
Phthalide, 3-(4-dimethylaminophenyl)-3-
(4-diethylamino-2-methylphenyl)-6-dimethylaminophthalide, 3-(p-dimethylaminophenyl)-3-(1,2-dimethylindol-3-yl)phthalide, 3-(p-dimethyl aminophenyl)-3
-(2-methylindol-3-yl)phthalide, 3,
3-bis(1,2-dimethylindol-3-yl)-
5-dimethylaminophthalide, 3,3-bis(1,2-
dimethylindol-3-yl)-6-dimethylaminophthalide, 3,3-bis(9-ethylcarbazole-3
-yl)-6-dimethylaminophthalide, 3,3-bis(2-phenylindol-3-yl)-6-dimethylaminophthalide, 3-p-dimethylaminophenyl-3
-(1-methylpyrrol-3-yl)-6-dimethylaminophthalide and other triarylmethane dyes, 4,4'
-bis-dimethylaminobenzhydrylbenzyl ether, N-halophenyl-leucoolamine, N-2,4
, 5-trichlorophenylleucoauramine and other diphenylmethane dyes, 3,3-bis[1,1-bis(4-
pyrrolidinophenyl)ethylene-2-yl]-4,5,
6,7-tetrabromophthalide, 3,3-bis[1-(
4-methoxyphenyl)-1-(4-dimethylaminophenyl)ethylene-2-yl]-4,5,6,7-tetrachlorophthalide, 3,3-bis[1-(4-methoxyphenyl)- Divinyl phthalide dyes such as 1-(4-pyrrolidinophenyl)ethylene-2-yl]-4,5,6,7-tetrachlorophthalide, thiazine dyes such as benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, etc. Dye, 3-Methyl-spiro-dinaphthopyran, 3-ethyl-spiro-dinaphthopyran, 3-phenyl-spiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho(6'-methoxybenzo)spiropyran, 3- Spiro dyes such as propyl-spiro-dibenzopyran, lactam dyes such as rhodamine-B-anilinolactam, rhodamine (p-nitroanilino) lactam, rhodamine (o-chloroanilino) lactam, 3-dimethylamino-7-methoxyfluor orane, 3-diethylamino-6-methoxyfluorane, 3-diethylamino-7-methoxyfluorane, 3-
Diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6,7-dimethylfluorane, 3-(N-
Ethyl-p-toluidino)-7-methylfluorane, 3
-dimethylamino-7-(N-acetyl-N-methylamino)fluorane, 3-diethylamino-7-N-methylaminofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-( N
-Methyl-N-benzylamino)fluorane, 3-diethylamino-7-(N-chloroethyl-N-methylamino)fluorane, 3-diethylamino-7-diethylaminofluorane, 4-benzylamino-8-diethylamino-benzo[a ]Fluorane, 3-[4-(4-dimethylaminoanilino)anilino]-7-chloro-6-methylfluoran, 3-[4-(4-phenylanilino)
Anilino]-7-chloro-6-methylfluorane, 8-
[4-(4-dimethylaminoanilino)anilino]-benzo[a]fluorane, 3-(N-ethyl-p-toluidino)-6-methyl-7-phenylaminofluorane,
3-(N-ethyl-p-toluidino)-6-methyl-7
-(p-toluidino)fluorane, 3-diethylamino-6-methyl-7-phenylaminofluorane, 3-di-n-butylamino-6-methyl-7-phenylaminofluorane, 3-di-n-pentyl Amino-6-methyl-7-phenylaminofluorane, 3-diethylamino-7-(2-carbomethoxy-phenylamino)fluoran, 3-(N-ethyl-N-isoamylamino)-6
-Methyl-7-phenylaminofluorane, 3-(N-
cyclohexyl-N-methylamino)-6-methyl-7
-phenylaminofluorane, 3-pyrrolidino-6-methyl-7-phenylaminofluorane, 3-piperidino-6-methyl-7-phenylaminofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane , 3-diethylamino-7-(o-chlorophenylamino)fluoran, 3-di-n-butylamino-7-(o
-chlorophenylamino)fluorane, 3-(N-ethyl-N-tetrahydrofurfuryl)amino-6-methyl-7-phenylaminofluorane, 3-pyrrolidino-6
-methyl-7-p-butylphenylaminofluorane,
3-(N-Methyl-N-n-propylamino)-6-methyl-7-phenylaminofluorane, 3-(N-ethyl-N-n-propyl)amino-6-methyl-7-phenylaminofluoran Orane, 3-(N-ethyl-N-isobutylamino)-6-methyl-7-phenylaminofluorane, 3-(N-methyl-N-n-hexylamino)-
6-Methyl-7-phenylaminofluorane, 3-(N
-ethyl-N-n-hexylamino)-6-methyl-7
-phenylaminofluorane, 3-(N-ethyl-N-
cyclopentylamino)-6-methyl-7-phenylaminofluorane, 3-[N-(3-ethoxypropyl)
-N-methylamino]-6-methyl-7-phenylaminofluorane, 3-[N-ethyl-N-(3-ethoxypropyl)amino]-6-methyl-7-phenylaminofluorane, 3-diethylamino -7-[m-(trifluoromethyl)phenylamino]fluorane, 3-diethylamino-7-(o-fluorophenylamino)fluorane, 3-dibutylamino-7-(o-fluorophenylamino)fluorane, 3-diethylamino -6-chloro-7-phenylaminofluorane, 3-(N-ethyl-N-isoamylamino)-7-(o-chlorophenylamino)fluorane, 3-(N-ethyl-N-n-hexylamino)- Fluoran dyes such as 7-(o-chlorophenylamino)fluorane, 3,6-bis(dimethylamino)fluorene-9-spiro-3'-(6'-dimethylamino)phthalide, 3-diethylamino-6-(
N-allyl-N-methylamino)fluorene-9-spiro-3'-(6'-dimethylamino)phthalide, 3,6
-bis(dimethylamino)-spiro[fluorene-9,
6′-6′H-chromeno(4,3-b)indole],
3,6-bis(dimethylamino)-3'-methyl-spiro[fluorene-9,6'-6H-chromeno(4,3-
b) indole], 3,6-bis(diethylamino)-
3'-Methyl-spiro[fluorene-9,6'-6H-
Fluorene dyes such as chromeno(4,3-b)indole], etc. Of course, it is not limited to these dyes,
Furthermore, it is also possible to use two or more types of dyes in combination, if necessary.

[0013] As the coloring agent used in the present invention, various known compounds can be used, and specific examples include the following. 4-tert-butylphenol, α-
Naphthol, β-naphthol, 4-acetylphenol, 4-tert-octylphenol, 4,4'-se
c-butylidene diphenol, 4-phenylphenol, 4,4'-dihydroxy-diphenylmethane, 4,
4'-isopropylidene diphenol, hydroquinone, 4,4'-cyclohexylidene diphenol, 4,
4'-(1,3-dimethylbutylidene)bisphenol, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis(6-tert) -Butyl-
3-methylphenol), 4,4'-dihydroxyphenylsulfone, 4-hydroxy-4'-methyldiphenylsulfone, 4-hydroxy-4'-methoxyphenylsulfone, 4-hydroxy-4'-isopropoxydiphenylsulfone, 4 -Hydroxy-3',4'-trimethylene diphenyl sulfone, 4-hydroxy-3',4
'-tetramethylenediphenylsulfone, 3,4-dihydroxy-4'-methyldiphenylsulfone, bis(3
-allyl-4-hydroxyphenyl)sulfone, 1,3
-di[2-(4-hydroxyphenyl)-2-propyl]benzene, hydroquinone monobenzyl ether, bis(4-hydroxyphenyl)acetic acid butyl ester, bis(4-hydroxyphenyl)acetic acid-2-phenoxyethyl ester, 4 -Hydroxybenzophenone, 2,4-
Dihydroxybenzophenone, 2,4,4'-trihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, dimethyl 4-hydroxyphthalate, methyl 4-hydroxybenzoate, ethyl 4-hydroxybenzoate, 4 -propyl hydroxybenzoate, 4
-Hydroxybenzoic acid-sec -Butyl, Pentyl 4-hydroxybenzoate, Phenyl 4-hydroxybenzoate, Benzyl 4-hydroxybenzoate, Tolyl 4-hydroxybenzoate, Chlorophenyl 4-hydroxybenzoate, Phenylpropyl 4-hydroxybenzoate phenethyl 4-hydroxybenzoate, p-chlorobenzyl 4-hydroxybenzoate, p-4-hydroxybenzoate
Methoxybenzyl, p-hydroxy-N-(2-phenoxyethyl)benzenesulfonamide, dimethyl 4-hydroxyphthalate, 1,5-bis(4-hydroxyphenylthio)-3-oxa-pentane, 1,7-bis (4
-hydroxyphenitio)-3,5-dioxa-heptane, 1,8-bis(4-hydroxyphenitio)-3,
Phenolic compounds such as 6-dioxa-octane, (4-hydroxyphenylthio)acetic acid-2-(4-hydroxyphenylthio)ethyl ester, novolak type phenolic resin, phenol polymer, benzoic acid, p-tert
-Butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec -butyl-4-hydroxybenzoic acid, 3
-Cyclohexyl-4-hydroxybenzoic acid, 3,5-
Dimethyl-4-hydroxybenzoic acid, salicylic acid, 3-
Isopropylsalicylic acid, 3-tert-butylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3-
Benzylsalicylic acid, 3-(α-methylbenzyl)salicylic acid, 3-chloro-5-(α-methylbenzyl)salicylic acid, 3-phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3,5-di-α -Methylbenzylsalicylic acid, 4-(2-p-methoxyphenoxyethoxy)
Aromatic carboxylic acids such as salicylic acid, 4-(3-p-tolylsulfonylpropyloxy)salicylic acid, 5-[p-(2-p-methoxyphenoxyethoxy)cumyl]salicylic acid, and these phenolic compounds, aromatic carboxylic acids and organic acidic substances such as salts with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel, and metal complex compounds such as antipyrine complexes of zinc thiocyanate. Note that two or more of these coloring agents can be used in combination as necessary.

The ratio of the basic dye to the coloring agent is not particularly limited, but generally 10% of the basic dye is used.
100 to 700 parts by weight, preferably 1 part by weight
About 50 to 400 parts by weight of coloring agent is used. In the heat-sensitive recording material of the present invention, the following compounds, for example, can be contained in the recording layer as a recording sensitivity improving agent for the purpose of obtaining suitability for high-speed recording. caproic acid amide, capric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, linolenic acid amide, N-methylstearic acid amide,
Stearic acid anilide, N-methyloleic acid amide,
Benzanilide, linoleic acid anilide, N-ethyl capric acid amide, N-butyl lauric acid amide, N-octadecyl acetamide, N-oleacetamide, N
-oleylbenzamide, N-stearylcyclohexylamide, polyethylene glycol, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester, 1,2-diphenoxyethane, 1,4-diphenoxybutane, 1 ,2-
Bis(3-methylphenoxy)ethane, 1,2-bis(
4-methoxyphenoxy)ethane, 1-phenoxy-2
-(4-chlorophenoxy)ethane, 1-phenoxy-
2-(4-methoxyphenoxy)ethane, 1-(2-methylphenoxy)-2-(4-methoxyphenoxy)ethane, dibenzyl terephthalate, dibenzyl oxalate, di(4-methylbenzyl oxalate) ester, p-benzyloxybenzoic acid benzyl ester, p-benzylbiphenyl, 1,5-bis(p-methoxyphenoxy)-3-oxa-pentane, 1,4-bis(2-vinyloxyethoxy)benzene, p- Biphenyl-p-tolyl ether, benzyl-p-methylthiophenyl ether, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-hydroxy-4
-benzyloxybenzophenone, etc. Note that the amount of recording sensitivity improver used is not particularly limited;
Generally 50 to 1000 parts per 100 parts by weight of basic dye
It is desirable to use it in parts by weight, preferably in the range of 100 to 500 parts by weight.

Coating liquids containing these are generally prepared by using water as a dispersion medium and using a stirring/pulverizing machine such as a ball mill, attritor, or sand mill to prepare specific phosphoric acid derivatives or their alkali metal salts, basic dyes, coloring agents, etc. It is prepared by dispersing them together or separately. Such coating liquids usually contain starches, hydroxyethyl cellulose, methyl cellulose, carboxyethyl cellulose,
Gelatin, casein, gum arabic, polyvinyl alcohol, styrene/maleic anhydride copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulsion, etc. are preferably about 2 to 40% by weight of the total solid content. is blended in an amount of about 5 to 25% by weight.

Furthermore, various auxiliary agents can be added to the coating liquid, such as dispersants such as sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salts, Other examples include antifoaming agents, fluorescent dyes, and colored dyes. In addition, inorganic pigments such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, and activated clay can be added to improve the adhesion of residue to the recording head. A dispersion or emulsion of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, or the like may be added to prevent sticking from contact with equipment or recording heads.

As the support, paper, plastic film, synthetic paper, etc. are appropriately selected and used. The method of forming the heat-sensitive recording layer is not particularly limited, and can be formed according to conventionally well-known and commonly used techniques. It is formed by coating on a support using an appropriate coating device such as a curtain coater or the like. Furthermore, the amount of coating is not particularly limited, and is generally 1 to 12 by dry weight.
It is adjusted within a range of about g/m2, preferably about 2 to 10 g/m2.

[0018] It is also possible to provide an overcoat layer on the heat-sensitive recording layer for the purpose of protecting the recording layer, or to provide an undercoat layer between the support and the recording layer. Various known techniques in the field of heat-sensitive recording material manufacturing can be added, such as providing a protective layer on the surface or applying adhesive processing to the back surface.

[0019]

[Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is of course not limited to these. Note that parts and percentages in the examples indicate parts by weight and percentages by weight, respectively, unless otherwise specified.

Example 1 ■ Preparation of liquid A 3-di-n-butylamino-6-methyl-7-phenylaminofluorane


10 parts 1,2-di(3-methylphenoxy)ethane
25 parts 5% methylcellulose aqueous solution

Part 5 Water


50 parts This composition was sand milled until the average particle size was 1.
It was ground to 0 μm. ■ Preparation of B solution 4,4'-isopropylidenephenol
20
Part Methyl cellulose 5% aqueous solution

Part 5 Water

55
part This composition was sand milled to an average particle size of 1.5 μm.
It was ground to m.

■ Preparation of liquid C diphenyl phosphate

10 parts 5% methylcellulose aqueous solution

Part 5 Water


35 parts This composition was ground with a sand mill until the average particle size was 2.0 μm. ■ Formation of heat-sensitive recording layer 90 parts of liquid A, 80 parts of liquid B, 50 parts of liquid C, silicon oxide pigment (
Mix and stir 7 parts of light calcium carbonate (oil absorption: 180 ml/100 g), 8 parts of light calcium carbonate (oil absorption: 90 ml/100 ml), 50 parts of a 20% aqueous polyvinyl alcohol solution, 15 parts of a 30% aqueous dispersion of zinc stearate, and 10 parts of water. I got the liquid. The resulting coating material was coated on a base paper having a basis weight of 45 g/m<2> so that the coated amount after drying was 3 g/m<2> and dried to obtain heat-sensitive recording paper.

Examples 2 to 9 Eight types of thermosensitive recording paper were obtained in the same manner as in Example 1, except that the following compounds were used in place of diphenyl phosphate in the preparation of liquid C in Example 1. Example 2: Bis(4-tert-butylphenyl) phosphate Example 3: Bis(2,4-di-tert-butylphenyl) phosphate Example 4: Sodium salt of diphenyl phosphate Example 5: Bis(4-tert-butylphenyl) phosphate -butylphenyl) phosphate Example 6: Potassium salt of bis(4-chlorophenyl) phosphate Example 7: Sodium salt of bis(4-α,α-dimethylbenzylphenyl) phosphate Example 8: Bis(4- Sodium salt of phenylphenyl) phosphate Example 9: Sodium salt of bis(2-phenylphenyl) phosphate When Solution C was an aqueous solution, it was used as it was without sand milling.

Example 10 A thermosensitive recording paper was obtained in the same manner as in Example 5, except that 5 parts of light calcium carbonate and 30 parts of water were used instead of 35 parts of water in the preparation of liquid C in Example 5. The mixture after the pulverization treatment has a ratio of sodium salt of bis(4-tert-butylphenyl) phosphate to calcium salt of bis(4-tert-butylphenyl) phosphate of 30:
It was 70.

Example 11 A thermosensitive recording paper was obtained in the same manner as in Example 5, except that 5 parts of magnesium silicate and 30 parts of water were used instead of 35 parts of water in the preparation of liquid C in Example 5. The mixture after the pulverization treatment has a ratio of sodium salt of bis(4-tert-butylphenyl) phosphate to magnesium salt of bis(4-tert-butylphenyl) phosphate of 50.
:50.

Example 12 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 5 parts of zinc oxide and 30 parts of water were used instead of 35 parts of water in the preparation of liquid C in Example 1. The mixture after pulverization is
The ratio of diphenyl phosphate to zinc salt of diphenyl phosphate was 60:40.

Comparative Example 1 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that Liquid C was not used in the preparation of Liquid C in Example 1.

Comparative Example 2 In the preparation of Solution C in Example 1, 4,4'-thiobis(3-methyl-6-t) was used instead of diphenyl phosphate.
Example 1 except that ert-butylphenol) was used.
A thermosensitive recording paper was obtained in the same manner as above.

The 14 types of thermal recording paper thus obtained were recorded using a thermal facsimile (Hitachi HIFAX-400 model), and the density of the recorded image and blank area was measured using a Macbeth densitometer (RD).
-100R type, amber filter used)
The results are shown in Table 1. In addition, the thermal recording paper after recording was
℃, 90%RH high humidity conditions (humidity resistance test) and 6
After being left under high temperature dry conditions (heat resistance test) at 0°C for 24 hours, the density of the recorded image and blank area was measured again using a Macbeth densitometer to evaluate the moisture resistance and heat resistance of the recorded image and blank area. The results are also listed in Table 1.

[0029]

[Table 1]

[0030]

[Effects of the Invention] As is clear from the results in Table 1, the heat-sensitive recording material of the present invention has excellent storage stability of recorded images, and is also an excellent heat-sensitive recording material with less background fog in blank areas. Ta.

Claims (3)

[Claims] Claim 1: A thermosensitive recording material utilizing a coloring reaction between a colorless or light-colored basic dye and a coloring agent, comprising at least one of a phosphoric acid derivative represented by the following general formula [Chemical formula 1] or an alkali metal salt thereof. A heat-sensitive recording material characterized by containing one kind of heat-sensitive recording material. [Formula 1] [In the formula, R1 to R10 each represent a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, an alkoxyl group, an aralkyloxy group, an aryloxy group, a hydroxyl group, or a halogen atom. In addition, R1, R2, R2
and R3, R6 and R7, and R7 and R8 may be bonded to each other to form a ring. ] 2. The heat-sensitive recording material according to claim 1, wherein the phosphoric acid derivative represented by the general formula [Formula 1] or its alkali metal salt is contained in the recording layer. 3. The heat-sensitive recording material according to claim 1 or 2, further comprising a polyvalent metal salt of a phosphoric acid derivative represented by the general formula [Formula 1].