JPS63137888A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a ferro-chelate series thermal recording material having high coloring performance and excellent long term preservation performance, by using microcapsules containing hydrophobic base and/or hydrophobic base having melting point of 70 deg.C or higher selectively as a decomposition catalyst. CONSTITUTION:A thermal recording layer containing (a) at least one selected from phenyl urethane for producing a phenol compound through thermal decomposition, silicon derivative of phenol or phospholic derivative group of phenol, (b) ferro-organic (III) compound and (c) microcapsules containing hydrophobic base and/or hydrophobic base having melting point of 70 deg.C or higher is provided onto a supporting material. Preferably, an organic phosphorus ferro compound having P-O...Fe<3+> and/or P-S...Fe<3+> bond is employed as said ferro-organic (III) compound because of its faint color when compared with other ferrate. Hydrophobic base having melting point higher than 90 deg.C is especially preferable, because a thermal recording material having excellent long term preservation performance can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an iron chelate thermosensitive recording material that has excellent color development and long-term storage stability.

``Prior art'' Heat-sensitive recording materials are inexpensive, can be recorded with relatively simple equipment, and are easy to maintain.
Because it has advantages such as no noise generation, it has been put to practical use in computer output, medical measurement recorders, facsimiles, printers, POS labels, tickets for vending machines, etc.

The thermosensitive recording material used in such a system generally utilizes a color reaction between two kinds of compounds, and a colored image is obtained by bringing the two substances into contact with each other using heat.

The coloring component used in this method is
A chelate type consisting of a combination of a long-chain fatty acid metal salt and a ligand compound as in No. 8787, a leuco type consisting of a combination of a leuco dye such as crystal violet lactone and a phenolic acidic substance as in Japanese Patent Publication No. 14039/1983, etc. has become publicly known.

However, in the case of leuco-based heat-sensitive recording materials, although clear colored images can be obtained on white substrates, when the colored images come into contact with plastics such as polyvinyl chloride, plasticizers and additives contained in the plastics may be removed. Disadvantages include poor stability of recorded images, such as fading easily due to aging, or easily fading when exposed to chemicals contained in food or cosmetics, or even fading when exposed to direct sunlight for a short period of time. have. Because of this drawback, the use of such leuco-based heat-sensitive recording materials is subject to certain restrictions, and improvement thereof is strongly desired.

On the other hand, in the case of conventional chelate-based heat-sensitive recording materials, although they are significantly superior to leuco-based materials in terms of the chemical resistance and light resistance of color-developed images, generally speaking, both color development and long-term storage stability of the recording materials are poor. It is inferior.

In addition, Japanese Patent Publication No. 56-25392 proposes a combination of linear fatty acid iron salt and phenyl urethane as a heat-sensitive recording material, but a combination of only these two components does not produce a product with good color development. . The same publication also states that ammonia, alkali metal hydroxides, aliphatic amines,
It has also been proposed to add low melting point or hydrophilic bases such as cycloaliphatic tertiary polyamines, hydroxyamines, organic or inorganic ammonium salts, morpholine derivatives, etc. as decomposition catalysts. However, although the addition of these bases greatly improves color development, the recording medium gradually develops color during long-term storage, resulting in new drawbacks such as a decrease in whiteness, making it impractical. .

"Problems to be Solved by the Invention" In view of the current situation, the present inventors have taken advantage of the characteristics of the chelate system, which has excellent recording image stability such as chemical resistance and light resistance, to achieve high color development and recordable images. We conducted intensive research to develop a chelate-based heat-sensitive recording medium that has excellent long-term storage properties.

As a result, by selectively using microcapsules encapsulating a hydrophobic base and/or a hydrophobic base with a melting point of 70°C or higher as a decomposition catalyst, we have succeeded in producing iron that has high color development and excellent long-term storage properties. It was discovered that a chelate-based recorder of angry heat could be obtained, and the present invention was completed.

"Means for Solving the Problem" The present invention provides (a) at least one member selected from the group of phenyl urethane, a silicon derivative of phenol, and a phosphorus derivative of phenol capable of producing a phenol compound by thermal decomposition; ) A heat-sensitive recording material comprising, on a support, a heat-sensitive recording layer containing an organic iron (III) compound and a microcapsule containing an fcl hydrophobic base and/or a hydrophobic base having a melting point of 70° C. or higher. It is.

"Function" The phenyl urethane used in the present invention, which can produce a phenol compound by thermal decomposition, has at least one of the following bonds in its molecule.

(However, Ar represents an aryl group which may have a substituent.) Such phenyl urethane is synthesized by a known method, for example, by reacting a phenol compound with an isocyanate compound.

Although the phenol compound used when synthesizing phenyl urethane is not limited to this, specific examples include the following.

Phenol, catechol, resorcinol, pyrogallol, phloroglucinol, p-phenylphenol, t
ert-butylcatechol, 4,6-tert-butylpyrogallol, 4,6-di-α-methylbenzylpyrogallol, 2,3-dihydroxynaphthalene, 4,4
'-Isopropylidenediphenol, 3.3', 4.4
'-Tetrahydroxyphenylsulfone, salicylic acid,
4-oxybenzoic acid, ethyl salicylate, benzyl 4-oxybenzoate, 3,5-di(α-methylhensyl)salicylic acid, hydroxynaphthoic acid, dihydroxybenzenesulfonic acid, gallic acid, ethyl gallate, propyl gallate, gallic acid Isoamyl, octyl gallate, lauryl gallate, stearyl gallate, hensyl gallate, tannic acid, pyrogallol tannic acid, protocatechuic acid, ethyl protocatechuate, pyrogallol-4-carboxylic acid, 8-hydroxyquinoline, dichloro-8-hydroxy Quinoline, dibromo-8-hydroxyquinoline, chlorobromo-8-hydroxyquinoline, methyl-8
-Hydroxyquinoline, butyl-8-hydroxyquinoline, lauryl-8-hydroxyquinoline, methylenebis(8-hydroxyquinoline), etc.

In addition, the isocyanate compound to be reacted with the above phenol compound is not limited to these, but
For example, phenyl isocyanate, p-chlorophenylisocyanate, hexamethylene-1,6-diisocyanate, tolylene diisocyanate, 2,4-1-lylene-diisocyanate, 3,3'-dimethyl-diphenyl-4,4'-diisocyanate, diphenylmethane-
4,4'-diisocyanate, naphthalene-1,5-diisocyato, dicyclohexylmethane diisocyanate, diphenyl ether-4,4'-diisocyanate, 3,3'-dimethyl-diphenylmethane-4,4'
-diisocyanate, triphenylmethane-triisocyanate, polymethylene phenyl isocyanate, and the like.

A silicon derivative of phenol that can produce a phenol compound by thermal decomposition has at least one of the following bonds in its molecule.

Ar-0-3t- (However, Ar represents an aryl group which may have a substituent.) Although the silicon derivative of such phenol is not limited to this, specifically naphthalene- Dioxo-2,3-dimethylsilane, naphthalene-dioxo-2
, 2'-diphenylsilane, dihydroxy-2,3-naphthalene-trimethylsilyl-diether, naphthalene-dioxy-2°3-bis(dimethylsilyl)-1,2
- Ethane etc. are exemplified.

Furthermore, phosphorus derivatives of phenol that can generate phenolic compounds by thermal decomposition have at least one of the following bonds in the molecule.

(However, Ar represents an aryl group which may have a substituent.) Examples of such phosphorus derivatives of phenol include, but are not limited to, hydrogen phosphate 2.3-
Examples include naphthyl, di(2-isopropyl-5-methylphenyl) phosphate, and the like.

The organic iron (1) compounds used in the present invention include: ■ organic phosphorus compounds having P -OH and/or P-3H bonds, ■ carboxylic acids, thio acids, dithio acids, ■
Examples include single or complex salts or mixed salts of organic sulfur compounds having an S-OH bond, and siloxane compounds such as polyferrophenylmethylsiloxane.

Among them, P-0...Fe3+ and/or p-s...
・An organophosphorus iron compound having a "Fe" bond is preferable because it is lighter in color than other iron salts, and in particular, it is a combination of at least one of the above organophosphorus compounds, a carboxylic acid, a thio acid,
A composite iron(II[) salt with at least one type of dithioic acid and an organic sulfur compound having a 5-OH bond is preferable because it is light in color and exhibits good color development.

P-0...Fe" and/or used in the present invention
.

Examples of organic phosphorous compounds having p-s...Fe'' bonds include iron(III) salts of compounds represented by the following general formulas (1) to (X■).

R.

R2-P-XIH (1) R,Xl-P-XZH(n) X, R5 RbXt　P　X3H([1) X, HX.

IIR? P
X2H(IV)R11P H(V) 2H X + H Rq X 2- P X :+ H(Vl)X+
X+ R1゜X2-P-H (■) Rz P X3H (■)
X 3 HX 2 H R, □X2 P XnH(IX) 3H X.

R, 1X2-P-X4H(X) ■ X 3 R+ 4 R,, -P -X3H(X I ) X zRlh R,? -P-X211 (X 11)I
II X + Xz RI9X3 P XS P X7R21 (
XT[I)□ X a R2゜ X, H X = Xz RzzXz P Xs P XTR23
(Xs)X , HX 61-1 l ]l RZ 4 COOP X s Rz s
(X~′) 2H X+ l( Rz h COOP X 3 H(X Yr )2
H×1 I RzqXz P N HR211(X■)3H 3H [In the formula, XxXz, Xz, Xa, and X each represent an oxygen atom or a sulfur atom, and R5 to RZ9 represent an alkyl group and an aryl group, respectively. ] The alkyl group represented by R1-R29 includes saturated and unsaturated substituted and unsubstituted alkyl groups, and may be any of a straight-chain alkyl group, a branched alkyl group, and a cycloalkyl group. These alkyl groups preferably have 1 to 20 carbon atoms, excluding carbon atoms in the substituent portion. Further, the aryl group represented by R1 to R2'l includes both an unsubstituted aryl group and a substituted aryl group, and the number of carbon atoms excluding the carbon atoms in the substituent part is 6.
-14 are preferred, and specific examples thereof include phenyl, naphthyl, anthryl and the like.

In addition, RI11! :R2, R3 and Ra, R5 and R6, R
Alkyl or aryl groups attached to the same phosphorus atom directly or through an oxygen or sulfur atom, such as 1ff and R, RIS and R16, R17 and R11+, and R19 and R2゜, are bonded to each other to form a 5-membered ring or A 6-membered ring may be formed, and when the group is an aryl group, they may be bonded at different positions of the same aromatic ring to form a 5- or 6-membered ring.

The carboxylic acid, thioic acid, and dithioic acid used in the present invention have the following general formula (XIX), and I R-C-Y-H (X I ru group, X.

Y represents an oxygen atom or a sulfur atom. ] Specific examples of the alkyl group or aryl group represented by R include:
R of the organic phosphorus compound.

- Saturated and unsaturated substituted and unsubstituted alkyl groups and substituted and unsubstituted aryl groups similar to those exemplified in R29 can be mentioned.

Examples of organic sulfur compounds having a 5-OH bond include sulfonic acids, sulfinic acids, sulfuric esters, and specific examples include benzenesulfonic acid, alkylhenzenesulfonic acids, naphthalenesulfonic acids, and alkylnaphthalenesulfonic acids. , polystyrene sulfonic acid, dialkyl sulfosuccinic acid, alkylbenzenesulfinic acid,
Examples include alkyl sulfate esters.

The hydrophobic base having a melting point of 70"C or more used in the present invention is not particularly limited, but the following may be exemplified.

N,N'-dicyclohexylguanidine, N,N'-dicyclohexyl-N"-(0-chloro)phenylguanidine, N,N'-synchrohexyl-N"-(p-ricolo)phenylguanidine, N.

N″-dicyclohexyl-N”-(2,4-dichloro)
Phenylguanidine, N,N'-dichlorohexyl-N''
-(3,4-dichloro)phenylguanidine, N, N'
- diphenylguanidine, N.

Guanidine derivatives such as N″-di-0-tolylguanidine; imidazole derivatives such as benzimidazole, 2-n-undecylimidazole, 2-heptadecyl imidazole, N,N′-diphenylformamidine, N-methyl-N,N '-Diphenylformamidine, N, N'-
Bis-(m-chlorophenyl)formamidine, N, N
'-Z-m-)lylformamidine, N,N'-diphenylacetamidine, N,N'-bis(p-bromophenyl)acetamidine, N,N'-diphenylbenzamidine, N,N'-bis( Amidine derivatives such as P-chlorophenyl)benzamidine, N,N'-di-p-tolylbenzamidine; N.

N', N'', N''-tetraphenyl-hexanecyamidine, N, N''-dicyclohexyludecanediamidine,
Cyamidine-derived tertiary, 1,2,3-triphenyl, such as N,N',N",N"-tetraphenyl-hebutanecyamidine, N,N",N',N"-tetraphenyl-decanecyamidine, etc. Isourea: 1,3-diphenyl-2-(p-tolyl)-isourea, 1,3-diphenyl-2-(p-chlorophenyl)-isohydride, 1,2.3) lycyclohexyl isourea, l , 3-diphenyl-2-(p-t
Isourea derivatives such as ert-butylphenyl)-isourea; 1,2.3-)liphenylthiourea, 1.3-
Isothiourea derivatives such as diphenyl-2-(p-nitrophenyl)-isothiourea and 1,3-di-m-tolyl-2-methylisothiourea; pyridine such as 2,6-diphenylpyridine and diphenyl-4-pyridylmethane Derivative; 4,4-dioctadecyl-2,2'-bipyridyl, 4
Dipyridine derivatives such as ゜4'-didodecyl-2,2-dipyridyl; trihensylamine, 1-naphthaleneacetic acid-
Pyrrolidinoethylamide, ■-Naphthaleneacetic acid-N-diisopropylaminoethylamide, TerephthalyW-N
-Tertiary amines such as diisopropylaminoethylamide, etc. can be mentioned. Among these compounds, the melting point is 9
Those with a temperature of 0'C or higher are particularly preferable because a heat-sensitive recording material with extremely excellent long-term storage stability can be obtained.

Furthermore, the hydrophobic base used in microcapsules can be either liquid or solid at room temperature, and can be mixed or dissolved in other hydrophobic media as needed. can.

Examples of such hydrophobic bases include, in addition to the above-mentioned hydrophobic bases having a melting point of 70'c or more, 3"-(4-pyrrolidino)-1,5-diphenylpenkune, 4-phenylpropylpyridine, 4-benzyl Pyridine, 4-(1-propenylbutene)pyridine, 4-octadecylpyridine,
Examples include, but are not limited to, 4-hexadecylpyridine.

Hydrophobic media used when preparing microcapsules encapsulating hydrophobic bases include, for example, vegetable oils such as cottonseed oil, mineral oils such as kerosene, paraffin, naphthenic oil, and chlorinated paraffin, and alkylated biphenyls. , aromatic hydrocarbons such as alkylated cuphenyl, alkylated naphthalene, diarylethane, triarylmethane, and diphenylalkane; alcohols such as oleyl alcohol, tridecyl alcohol, benzyl alcohol, 1-phenylethyl alcohol, and glycerin; Esters such as dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, dioctyl phthalate, diethyl adipate, propyl adipate, di-n-butyl adipate, dioctyl adipate, tricresyl phosphate, tributyl phosphate , organic phosphorus compounds such as tributyl phosphite and tributylphosphine oxide, ethers such as phenyl cellosolve, henzyl carbitol, polypropylene glycol, propylene glycol monophenyl ether, N, N
- Amides such as dimethyl lauramide, N, N-dimethyl stearamide, N, N-dihexyl octylamide,
Examples include ketones such as diisobutyl ketone and methylhexyl ketone, and alkylene carbonates such as ethylene carbonate and propylene carbonate.

In addition, any of the conventionally known methods such as coacervation method, interfacial polymerization method, and 1 n situ method can be used for microcapsulation, and preferable membrane materials include urethane resin, urea resin, and urea resin. −
Examples include formaldehyde resins.

As mentioned above, the heat-sensitive recording material of the present invention comprises (a) at least one member selected from the group of phenyl urethane, a silicon derivative of phenol, and a phosphorus derivative of phenol that can produce a phenol compound by risa decomposition; It has an extremely important feature in that it uses three components as essential components: (1) a compound, and (c) a microcapsule containing a hydrophobic base and/or a hydrophobic base with a melting point of 70°C or higher.

The blending ratio of these three components should be selected appropriately depending on the combination of materials used, but (al component [hereinafter referred to as
Blocked phenol compound]: (b) component [
Organic iron (III) compound): component (c) [hydrophobic base]
The weight ratio is 1:0.02~50:0.05~
20, especially 1:O,I
-10: It is more preferable to use it so that it may become 0.2-5.

In addition to the above-mentioned three components, the recording layer of the heat-sensitive recording material of the present invention may contain fillers, binders, dispersants, color development inhibitors, enhancers, anti-sticking agents, ultraviolet absorbers, Coloring agents, fluorescent dyes, preservatives, antifoaming agents, inorganic acids, leuco dyes, color developers, diazonium compounds, couplers, and the like can also be added.

Examples of fillers include oxides, hydroxides, carbonates, and sulfates of aluminum, zinc, magnesium, calcium, and titanium, or halogen compounds, silica, acid clay,
Examples include activated clay, acpargite zeolite, hentonite, kaolin, calcined kaolin, talc, alumina, pigments as described in JP-A-55-103994, fine melamine resin particles, fine urea resin particles, fine styrene resin particles, and the like.

Binders include proteins such as gelatin, albumin, and casein; HBs such as grain starch, pregelatinized starch, oxidized starch, etherified starch, and esterified starch; celluloses such as carboxymethyl cellulose and hydroxyethyl cellulose; agar; and sodium alginate. , water-soluble natural polymer compounds such as sucrose such as gum arabic; water-soluble synthetic polymer compounds such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, maleic acid copolymer, etc.; styrene-butadiene latex, acrylonitrile Latex necks such as pukudiene latex, acrylic acid ester latex, vinyl acetate latex, methyl methacrylate-butadiene latex, and their carboxy-modified (e.g. acrylic acid) latex; polyester, polystyrene, chlorinated rubber, polyvinyl acetate, polyester. Vinyl chloride, polybutadiene, acrylic ester, vinyl chloride
Vinyl acetate copolymer, polybutadiene, styrene-butadiene-acrylic copolymer, polyethylene, ethylene-
Examples include oil-cooling polymer compounds such as vinyl acetate copolymer, styrene-acrylic copolymer, polyvinylidene chloride, vinylidene chloride-acrylic copolymer, phenol resin, urea-formalin resin, and melamine resin.

Examples of dispersants include sodium alkyl sulfate, sodium alkyl hanzene sulfonate, sodium alkylnaphthalene sulfonate, sodium polystyrene sulfonate, sodium oleamide sulfonate, sodium dialkyl sulfosuccinate, sulfated castor oil, and the like. Ion activator; Cation activator such as halogenated trimethylaminoethyl alkylamide, alkylpyridinium sulfate, halogenated alkyltrimethylammonium; polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, polyoxyethylene alkylphenyl ether, polyhydric Nonionic surfactants such as alcohol fatty acid ester, polyoxyethylene polyhydric alcohol fatty acid ester, sucrose fatty acid ester; surfactants such as amphoteric surfactants such as alkyltrimethylaminoacetic acid and alkyldiethylenetriaminoacetic acid, starch, phosphorylated starch, Polyvinyl alcohol, carboxymethyl cellulose, sodium alginate, sodium polyacrylate, sodium salt of vinyl acetate-maleic anhydride copolymer, ammonium salt of styrene-maleic anhydride copolymer, sodium salt of butadiene-methacrylic acid copolymer, etc. Low-molecular or high-molecular dispersants and surfactants such as water-soluble high-molecular compounds are used.

As the color development inhibitor, P -OH and/or P -
Organophosphorous compounds represented by the above general formulas (I) to (X) having S H bonds, ethylenediaminetetraacetic acid (ED
Examples include compounds having an aminocarboxylic acid group such as TA), trans-1,2-cyclohexanediaminetetraacetic acid (CyDTA), and inorganic phosphoric acids such as phosphoric acid and polyphosphoric acid.

Examples of the sensitizer include neutral or acidic thermofusible substances having a melting point in the range of 50°C to 250°C, such as diphenyl carbonate, di-4-methylphenyl carbonate, charcoal M,';-
Examples include 3-chlorophenyl, 1,2-bis(3-methylphenoxy)ethane, and the like.

In addition, anti-sticking agents include waxes such as paraffin wax, carnauba wax, microcrystalline wax, polyethylene wax, stearamide, laurylamide, myristylamide, palmitic acid amide; zinc stearate, aluminum stearate, calcium stearate, etc. Examples include metal soaps.

In the present invention, the three components fn), (b) and (C) are water, benzene, toluene, xylene, n
- Dissolve or disperse in a non-polar organic solvent such as hexane, n-hebutane, cyclohexane, kerosene, etc., or a polar organic solvent such as methyl isobutyl ketone, methyl cellosolve, acetone, methyl ethyl ketone, dimethyl ether, etc., and use a ball mill or sand cline as necessary. It is prepared as a coating liquid by pulverizing it using a grinder or the like.

The snow solution containing these three components is then applied to -C as a layer or a mixed layer on a support to form a heat-sensitive recording layer. The coating solution containing the remaining components is coated on a separate support to form a transfer type heat-sensitive recording material, or other heat-sensitive recording material such as leuco or diazo is applied above or below the recording layer containing the three components. It can also be used in forms known in the art, such as forming layers to form a multicolor thermosensitive recording material, or providing a nitrogen barcode layer on the recording layer.

The coating solution prepared as described above is coated on a suitable support such as paper, plastic film, synthetic paper, metal film, etc., but the coating method is not particularly limited, and can be coated according to a conventional method, for example. A dry weight of 3 to 1
It is applied so that it is about 5 g/d.

"Example" The present invention will be described in more detail with reference to Examples below, but it is of course not limited to these. In addition, unless otherwise specified, parts and percentages in examples are parts and percentages by weight.
shows.

Example 1 ■ Preparation of Blocked Isoamyl Gallate - In a three-piece detachable flask equipped with a stirrer, reflux, and dropping funnel, 12 parts of isoamyl gallate, 100 parts of anhydrous methyl ethyl ketone (MEK) and a few drops of triethylamine was added thereto, and while stirring, 18 parts of phenyl isocyanate was added dropwise from the dropping funnel to obtain a white precipitate. This precipitate was filtered, washed with MEK, and then dried to obtain blocked isoamyl gallate.

■ Blocked isoamyl gallate mentioned above 30 parts Polyvinyl alcohol 10% aqueous solution 10 parts Sodium dodecylhenzensulfonate 0.2 parts Water
100 parts of this composition was ground with a sand grinder until the average particle size was 3 μm.

■ Solution B: ferric diphenyl phosphate salt 25 parts polyvinyl alcohol 10% aqueous solution 10 parts water
100 parts of this composition was ground with a sand grinder until the average particle size was 3 μm.

■ N, N'-diphenylhenzamidine manufactured by Colored Glass 30 parts Methylcellulose 5% aqueous solution 20 parts water
100 parts of this composition was ground with a sand grinder until the average particle size was 3 μm.

■ Formation of 1i=140.2 parts of solution A, 135 parts of solution B, 150 parts of solution C, 5 parts of silicon oxide pigment, 50 parts of 20% oxidized starch aqueous solution, and 0.3 part of phenylphosphonic acid were mixed and stirred. 50% of coating liquid
A thermal recording paper was obtained by coating and drying the mixture on a base paper of g/rd so that the dry weight became Log/ffl.

Example 2 Thermosensitive recording paper was obtained in the same manner as in Example 1 except that 25 parts of ferric p-tert-butylbenzoate was used instead of 25 parts of ferric diphenyl phosphate in the preparation of liquid B. Ta.

Example 3 Same as Example 1 except that in the preparation of Solution B, 25 parts of a 1:1 composite salt of p-tert-butylbenzoic acid and diphenyl phosphate was used instead of 25 parts of ferric diphenyl phosphate. A thermosensitive recording paper was obtained in the same manner.

Example 4 Solution C 11 Same as above except that in A, 30 parts of N,N'-dicyclohexyl-N"-(0-chloro)phenylguanidine was used instead of 30 parts of N,N'-diphenylhenzamidine. A thermosensitive recording paper was obtained in the same manner as in Example 1.

Example 5 c In Liquid 5FFA m, 1,3-diphenyl-2 was used instead of 30 parts of N,N'-diphenylhenzamidine.
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 30 parts of -(p-)lyl)isourea was used.

Example 6 C? A thermosensitive recording paper was obtained in the same manner as in Example 1, except that 30 parts of diphenyl-4-pyridylmethane was used in place of 30 parts of N,N'-diphenylhenzamidine.

Example 7 730 parts of 3-(4-pyridyl)-i5-diphenylpeta and polyvalent isocyanate (trade name: Takenate I)-11
A solution containing 15 parts of ON) was added to 100 parts of a 6% polyvinyl alcohol aqueous solution, emulsified, and the average particle size was 2.0.
After μ, 1. This system was reacted at 60° C. for 2 hours to obtain a capsule dispersion containing a hydrophobic base.

A thermosensitive recording paper was obtained in the same manner as in Example 1 except that the above capsule dispersion liquid was used instead of liquid C.

Example 8 In preparing solution A, blocked isoamyl gallate 30
A thermosensitive recording paper was obtained in the same manner as in Example 1, except that 30 parts of naphthalene-dioxo-2°3-diphenylsilane was used instead of 30 parts of naphthalene-dioxo-2°3-diphenylsilane.

Example 9 In preparing solution A, blocked isoamyl gallate 30
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 30 parts of 2.3-naphthyl hydrogen phosphate was used instead of 30 parts of 2.3-naphthyl hydrogen phosphate.

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

Comparative Example 2 The same procedure as in Example 1 was carried out, except that instead of using carbon, 30 parts of tri-n-octylamine was emulsified in 120 parts of 3% polyvinyl alcohol to prepare an emulsion with an average particle size of 3 μm. A thermosensitive recording paper was obtained.

Comparative Example 3 A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 30 parts of triethanolamine was used instead of liquid C.

The 12 types of heat-sensitive recording paper thus obtained were pressed against a hot plate at 140°C for 3 seconds to develop color, and the color density was measured using a Macbeth densitometer (model RD-100R, using Amber Fill Coup). The results are shown in Table 1. Next, after storing the recording paper for one month, the whiteness of the background portion was measured using a Hunter whiteness meter, and the results are also listed in Table 1.

7 Effects in Table 1 As is clear from the results in Table 1, all of the heat-sensitive recording materials of the present invention were excellent in color development and long-term storage stability.

Claims (3)

[Claims] (1) (a) at least one member selected from the group of phenyl urethane, silicon derivatives of phenol, and phosphorus derivatives of phenol that can produce phenolic compounds by thermal decomposition; (b) an organic iron (III) compound; c.
) A thermosensitive recording material comprising a microcapsule containing a hydrophobic base and/or a thermosensitive recording layer containing a hydrophobic base having a melting point of 70° C. or higher on a support. (2) The heat-sensitive recording material according to claim (1), wherein the hydrophobic base has a melting point of 90° C. or higher. (3) Organic iron (III) compound is P-O^-...Fe^3^
The heat-sensitive recording material according to claims (1) and (2), which is an organophosphorous iron compound having + and/or P-S^-...Fe^3^+ bonds.