JP2002326464A - Heat-sensitive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive recording medium which has a high speed recording suitability, excellent preservability of a recording image without reducing the whiteness of a recording layer even when the layer is preserved under a high temperature condition and which has small yellowing of a skin part due to a light. SOLUTION: The heat-sensitive recording medium comprises a heat-sensitive recording layer which contains a colorless or pale basic dye, and a colorant which colors in contact with the dye in such a manner that as the colorant, a mixture of 3-(p-hydroxyphenyl)-1,1,3-trimethyl-5-indanol and a specific phenol compound is used, as the dye, a specific fluoran compound is used, further as a color developability improver, a compound selected from the group consisting of dibenzyl oxalate, di(p-methylbenxyl)oxalate, 2- benzyloxynaphthalene, m-terphenyl, p-benzylbiphenyl, 4-(p-methylphenoxy) biphenyl, 1,2-bis(phenoxy)ethane and 1,2-bis(3-methylphenoxy)ethane is contained in the heat-sensitive recording layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermosensitive recording medium,
The present invention relates to a thermosensitive recording medium having high sensitivity, excellent storage stability of a recorded image without a decrease in whiteness of a white paper portion, and little yellowing due to light in a background portion.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive recording material comprises a colorless or light-colored basic dye and an organic colorant such as a phenolic compound.
After dispersing into fine particles, they are mixed together, and a binder, a filler, a coloring agent, a lubricant and other auxiliaries are added, and the obtained coating liquid is used as a recording layer to support paper, synthetic paper, plastic film, etc. 2. Description of the Related Art A thermosensitive recording material which is applied to a body and which is used to obtain a recorded image by contacting both coloring materials by heating with a hot pen, a thermal head, a hot stamp or the like is well known. Recently, these thermal recording systems can be operated at high speeds, such as facsimile machines, automatic ticket vending machines, barcode labels,
It is applied to a wide range of fields such as measurement recorders. However, as recording devices become more diversified and have higher performance, the required quality of thermosensitive recording media is becoming higher. For example, it is required that high-density and clear recording images can be obtained even with a small amount of thermal energy without decreasing the whiteness of the recording paper before recording as the recording speed increases. May be left at about 40 ° C. for a long time, in which case the color reaction may proceed to cause color fogging.

[0003] The thermosensitive recording medium generally has a problem in the preservability of the recorded image, and particularly has a disadvantage that the recorded image fades in a relatively short time under a high temperature condition. For the purpose of improving the storage stability of the recorded image, methods using various storage stability have been proposed, but sufficient effects cannot be obtained,
Further, even those which are effective have new defects such as lowering of whiteness, and satisfactory results have not been obtained.

[0004] Further, a thermosensitive recording medium using a basic dye or an acidic substance as a colorant, which is generally used, has poor stability against light, and when used outside, there is a problem that the entire recording medium turns yellow, and improvement is desired. Was rare.

As a conventional example of a heat-sensitive recording material, a heat-sensitive recording material using an indanol derivative as a colorant is disclosed in JP-A-57-41991 and JP-A-60-260386, for example. In this case, the thermal response was low, and a sufficient color density could not be obtained during high-speed recording.
In addition, the background portion before recording tends to turn yellow by light, and when the recorded image is stored at a high temperature, the image density is remarkably reduced, and satisfactory results cannot be obtained.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides high-speed recording suitability, excellent storage stability of recorded images without lowering the whiteness of the recording layer even when stored under high-temperature conditions, and uses light. It is an object of the present invention to provide a thermosensitive recording medium with less yellowing of the background.

[0007]

Means for Solving the Problems The present inventors have proposed a thermosensitive recording medium in which a recording layer containing a specific colorless or light-colored basic dye and a coloring agent is provided on a support. 3- (p-hydroxyphenyl) -1,1,3-trimethyl-5-indanol as a coloring agent and the following general formulas [1] to
The present invention has been completed by using the compound [7] in combination with a specific basic dye and a specific color developing agent.

[0008]

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[0009]

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[0010]

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[0011]

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[0012]

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[0013]

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[0014]

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The 3- (p-hydroxyphenyl) -1,1,3-trimethyl-5-indanol used in the present invention can be produced by a known method. For example, 2,4-di (p-hydroxyphenyl) -4-methyl-pentene- which is a linear dimer of p-isopropenylphenol
Cyclization reaction of a mixture of phenol 1 and pentene-2 in the presence of an acid catalyst (JP-A-56-19333, JP-A-4-26644, etc.), decomposition and cyclization of bisphenol A with an acid catalyst (For example, JP-A-5-294879, U.S. Pat. No. 2,979,534) and the like. The obtained 3- (p-hydroxyphenyl) -1,1,3-trimethyl-5-indanol is
The type and amount of impurities contained in the raw materials and by-products vary depending on the production method and production conditions, but 95% by weight of 3- (p-hydroxyphenyl) -1,1,3-trimethyl-5-indanol is contained. Or more (preferably 97% by weight or more)
If it is contained, the effects of the present invention can be obtained. Among them, a high-purity compound having a melting point of 194 to 199 ° C. (preferably 195 to 199 ° C.) can reduce the whiteness of the background portion of the thermosensitive recording medium and the yellowing to light. On the other hand, it is preferable because it exhibits particularly excellent effects.

The amount of the colorant used is not particularly limited, but is generally 50 to 1 with respect to 100 basic dye receiving parts.
It is preferably used in an amount of about 000 parts by weight, particularly about 150 to 700 parts by weight.

The compound represented by the general formula [1] includes
p-Hydroxybenzoic acid benzyl ester, p-hydroxybenzoic acid-p-methylbenzyl ester, and compounds represented by the general formula [2] include 4,4′-thiobis (2-methylphenol) and 4,4′- Thiobis (2
3-dimethylphenol), the compound represented by the general formula [3] includes 2,2′-thiobis (4-t-octylphenol), and the compound represented by the general formula [4] includes 4,4 ′ -Dihydroxy-diphenyl sulfone,
2,4'-dihydroxy-diphenylsulfone, 4-hydroxy-4'-i-propoxy-diphenylsulfone, 3,3'-diallyl-4,4'-dihydroxy-diphenylsulfone, represented by the general formula [5] As the compound, 2,2-bis (4-hydroxyphenyl) -4-
Methylpentane, 2,2-bis (4-hydroxyphenyl) -n-heptane, 1,1-bis (4-hydroxyphenyl) acetic acid butyl ester, n-butyl-4,4-bis (4-hydroxyphenyl) Pentanoate, 1,1,
1-tris (p-hydroxyphenyl) ethane, 4,
4 '-{1- [4- (2- (4-hydroxyphenyl)
-2-propyl] phenyl] ethylidene-bisphenol, the compound represented by the general formula [6] includes 2,4-
Bis (4-hydroxyphenyl) -4-methylpentane, 4-methyl-2,4-bis (4-hydroxyphenyl) -pent-1-ene, 3,4-bis (4-hydroxyphenyl) hexane, general formula As the compound represented by [7], 2 ′, 4-dihydroxybenzophenone,
4,4'-dihydroxybenzophenone and the like, but are not limited thereto.

In such a color former composition, 3- (p-
(Hydroxyphenyl) -1,1,3-trimethyl-5-
If the amount of the compound of the general formulas [1] to [7] to indanol is too small, there is no effect, and if it is too large, new disadvantages such as lowering of the whiteness of the recording paper are caused. p-hydroxyphenyl) -1,1,3-
For 100 parts by weight of trimethyl-5-indanol,
At least one of the compounds of the general formulas [1] to [7]
It is good to use in the range of 100 to 100 parts by weight, preferably 10 to 80 parts by weight, more preferably 20 to 70 parts by weight.

Examples of basic dyes include 3-di-n-butylamino-6-methyl-7-anilifluoran and 3-di-
n-pentylamino-6-methyl-7-anilino-fluoran, 3- (Ni-pentyl) ethylamino-6-
By using at least one member selected from the group consisting of methyl-7-anilinofluoran and 3-diethylamino-6-methyl-7-anilinofluoran, the object of the present invention is achieved, but the desired effects are achieved. The other basic dyes applicable to this kind of heat-sensitive recording material may be used together as long as the above range can be maintained.

For example, fluoran compounds, triaryl methane phthalides, fluorene phthalides, divinyl phthalides, phenothiazines, auramines, spiropyrans, rhodamine lactams, etc.
3-N-ethyl-N-isopropylamino-6-methyl-7-anilinofluoran, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, 3-N-methyl- N-isobutylamino-6-methyl-7-anilinofluoran, 3-N-ethyl-Np
-Tolylamino-6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3-N-ethyl- N-tetrahydrofurfurylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-anilinofluoran,
3-N-ethyl-N- (2-ethoxypropyl) amino-6-methyl-7-anilinofluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-
Di-n-butylamino-7- (o-chloroanilino) fluoran, 3-diethylamino-7- (o-trifluoromethylanilino) fluoran, 3-diethylamino-
7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-N-ethyl-Np-tolylamino-7-methylfluoran, 3 -Diethylamino-7,8-benzofluoran, 3-diethylamino-
7-t-butylfluoran, 3-N-ethyl-Np-
Tolylamino-7-N-methyl-N-phenylaminofluoran, 3-diethylamino-7-dibenzylaminofluoran, 2-methyl-6-p- (p-dimethylaminophenyl) aminoanilinofluoran, 2- Chloro-
3-methyl-6-p- (p-dimethylaminophenyl)
Fluoran compounds such as aminoanilinofluoran, 3,
3-bis (p-dimethylaminophenyl) phthalide,
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3- (p -Dimethylaminophenyl)-
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-ethylcarbazol-3-yl) -6-dimethylaminophthalide,
3,3-bis (2-finylindol-3-yl)-
6-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-3-yl) -6
Triarylmethanephthalide compounds such as -dimethylaminophthalide, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, 3,6-bis (diethylamino) Fluorene-
Fluorenephthalide compounds such as 9-spiro-3 ′-(6′-dimethylamino) phthalide, 3,3-bis [2-
(P-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [2- (p-dimethylaminophenyl) -2- (P-methoxyphenyl) ethenyl]-
4,5,6,7-tetrabromophthalide, 3,3-bis [2- (p-pyrrolidinophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrachloro Divinylphthalide compounds such as phthalide, phenothiazine compounds such as benzoylleucomethylene blue, 4,
Auramine compounds such as 4'-bisdimethylaminobenzohydryl benzyl ether, No-chlorophenyl-leuco auramine, spiropyran compounds such as 3-methyl-spiro-dinaphthopyran, 3-ethyl-spirodinaphthopyran, rhodamine B- Lactam compounds such as anilinolactam and rhodamine (p-nitroanilino) lactam are exemplified.

Examples of color improvers include oxalic acid-dibedyl ester, oxalic acid-di (p-methylbenzyl) ester,
-Benzyloxynaphthalene, m-terphenyl, p-
Benzylbiphenyl, 4- (p-methylphenoxy) biphenyl, 1,2-bis (phenoxy) ethane and 1,
At least one selected from the group consisting of 2-bis (3-methylphenoxy) ethane may be used, but other color improvers may be used in combination as long as the desired effects of the present invention are not impaired. Examples of such a color developing agent include fatty acid amides such as stearic acid amide, methylene bisamide stearate, ethylene bisamide stearate, methylolamide stearate, oleic acid amide, palmitic acid amide and coconut fatty acid amide, dibenzyl terephthalate, 1-hydroxy- 2-naphthoic acid phenyl ester and the like.

The amount of these color formers is not particularly limited, but is generally 10 to 700 parts by weight, preferably 20 to 5 parts by weight, per 100 parts by weight of the basic dye.
It is preferable to adjust the amount in the range of 00 parts by weight.

In the present invention, by using a combination of the above-mentioned specific basic dye, a specific coloring agent and a specific coloring property improving agent, it can be handled for a long time in an environment under high temperature and high humidity. Can provide a heat-sensitive recording material having sufficient whiteness and record preservability. However, in the recording layer, a hindered phenolic compound represented by the following general formulas [8] to [12] and / or a general formula By incorporating a compound selected from the group consisting of the phosphates of the hindered phenolic compounds represented by the formula [13] and salts thereof, it is possible to obtain a thermosensitive recording material having further improved storage stability of recorded images.

[0024]

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[0025]

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[0026]

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[0027]

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[0028]

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[0029]

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The compound represented by the general formula [8] includes
4,4′-thiobis (6-t-butyl-m-cresol), 4,4′-thiobis (6-t-butyl-o-cresol), 4,4′-thiobis (2,6-di-t -Butylphenol), general formula

Examples of the compound represented by [9] include 2,2′-methylenebis (4-methyl-6-t-butylphenol), 2,2′-methylenebis (4-ethyl-6-t-butylphenol), 2,2 '-Ethylidenebis (4,6-di-t-butylphenol), 2-t
-Butyl-6- (3-t-butyl-2-hydroxy-5
-Methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate, general formula [ 10] include 4,4′-butylidene (6-t-butyl-
m-clay sol), 1,1,3-tris (2-methyl-
4-hydroxy-5-cyclohexylphenyl) butane, a compound represented by the general formula [11],
3,5-tris (4-t-butyl-3-hydroxy-
2,6-dimethylbenzyl) isocyanuric acid, 1,3
5-Tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanuric acid, a compound represented by the general formula [12], includes 1,3,5-tris (3,5-di-t
-Butyl-4-hydroxybenzyl) -2,4,6-trimethylbenzene, and the compound represented by the general formula [13] include 2,2′-methylenebis (4,6-di-t-butyl) phosphate and Metal salts of these potassium, sodium, zinc, calcium, magnesium, aluminum and the like can be mentioned.

The amount of the preservability improver is not particularly limited, but is generally 10 to 500 parts by weight, preferably 30 to 35 parts by weight, per 100 parts by weight of the specific basic dye.
It is preferable to adjust within the range of 0 parts by weight.

The coating liquid containing these is generally mixed with water as a dispersing medium, and a dye, a pigment, a stirrer or a pulverizer such as a ball mill, an attritor, a vertical or horizontal sand mill, or a colloid mill is used.
It is prepared by dispersing a color former, a color improver, a preservability improver and the like together or separately. In such a coating liquid, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy group-modified polyvinyl alcohol, various modified polyvinyl alcohols such as silicon-modified polyvinyl alcohol as a binder, Styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, etc. are 2 to 40% by weight of the total solid, preferably 5 to 5% by weight. About 25% by weight is blended. Of course, two or more of these binders can be used in combination.

Further, various auxiliaries can be added to the coating liquid. Examples of these auxiliaries include dispersants such as dioctyl sulfosuccinate sodium salt and fatty acid metal salt, benzophenone-based, cyano-based, and the like. Examples include acrylate-based and hydroxybenzoate-based ultraviolet absorbers, other antifoaming agents, fluorescent dyes, direct-color dyes, and the like.

Further, a stearic acid ester wax, polyethylene wax,
Dispersions and emulsions of carnauba wax, microcrystalline wax, modified carboxy paraffin wax, zinc stearate, calcium stearate and the like can also be added.

In addition, inorganic pigments such as kaolin, clay, talc, calcium carbonate, magnesium carbonate, calcined clay, titanium oxide, diatomaceous earth, finely divided anhydrous silica, activated clay, and the like, styrene Organic pigments such as balls, nylon powder, polyethylene powder, urea / formalin resin filler, and raw starch granules can also be added.

In the heat-sensitive recording medium of the present invention, the method for forming the recording layer is not particularly limited, and the recording layer can be formed according to a conventionally known technique. For example, a coating solution for a heat-sensitive recording layer is coated on a support with an appropriate coating device such as an air knife coater, a blade coater, a bar coater, a gravure coater, and a curtain coater.
Dry to form a recording layer.

The coating amount of the coating liquid is not particularly limited, and is generally 1.0 to 12 g / dry weight.
m ² , preferably in the range of 1.5 to 10 g / m ² . As the support, paper, plastic film, synthetic paper and the like are used, but paper is most preferably used in view of cost and applicability.

The heat-sensitive recording material of the present invention thus obtained is
Even when exposed to high-temperature conditions, it exhibits excellent characteristics such that the decrease in whiteness and recording density is extremely small, and the yellow discoloration due to light in the background is small. If necessary, a protective layer may be provided on the front and / or back surface of the thermosensitive recording medium, or an intermediate layer may be provided between the support and the thermosensitive recording layer. Various known techniques in the field of recording medium production can be added.

[0039]

The present invention will be described in more detail with reference to the following Examples, but it should be understood that the present invention is by no means restricted thereto. Unless otherwise specified, parts and% in the examples indicate parts by weight and% by weight, respectively. Example 1 Preparation of Solution A 3-Di-n-butylamino-6-methyl-7-anilinofluorane 10 parts 2-benzyloxynaphthalene 25 parts Methylcellulose 5% aqueous solution 15 parts Water 120 parts This composition was averaged with a sand mill. It was pulverized to a particle size of 1.5 μm. Solution B preparation 3- (p-hydroxyphenyl) -1,1,3-trimethyl-5-indanol (mp. 195-196 ° C.) 15 parts p-hydroxybenzoic acid benzyl ester 10 parts methylcellulose 5% aqueous solution 30 parts water 70 Part This composition was pulverized with a sand mill until the average particle size became 1.5 μm. Formation of recording layer 170 parts of liquid A, 125 parts of liquid B, silicon oxide pigment (oil absorption 1
80 ml / 100 g) 30 parts, 20% oxidized starch aqueous solution 15
0 parts and 55 parts of water were mixed and stirred to obtain a coating liquid. The obtained coating solution was applied to 50 g / m ² base paper so as to have a dry weight of 6 g / m ² and dried to obtain a thermosensitive recording medium.

Example 2 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that 4,4'-thiobis (2-methylphenol) was used instead of benzyl p-hydroxybenzoate in Preparation of Solution B. Was.

Example 3 A heat-sensitive recording material was prepared in the same manner as in Example 1 except that 2,2'-thiobis (4-t-octylphenol) was used instead of benzyl p-hydroxybenzoate in Preparation of Solution B. Obtained.

Example 4 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that 4,4'-dihydroxy-diphenylsulfone was used instead of benzyl p-hydroxybenzoate in the preparation of Solution B.

Example 5 In Preparation of Solution B, 4,4 '-{1- [4- [2- (4-hydroxyphenyl) -2-propyl] phenyl] ethylidene} bisphenol was used instead of benzyl p-hydroxybenzoate A thermosensitive recording medium was obtained in the same manner as in Example 1 except that

Example 6 Example 1 was repeated except that 4-methyl-2,4-bis (4-hydroxyphenyl) -pent-1-ene was used instead of benzyl p-hydroxybenzoate in the preparation of solution B. In the same manner as in the above, a thermosensitive recording medium was obtained.

Example 7 A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 4,4'-dihydroxybenzophenone was used instead of benzyl p-hydroxybenzoate in the preparation of Solution B.

Example 8 In the preparation of solution A, 3- (N-i-yl) was used instead of 3-di-n-butylamino-6-methyl-7-anilinofluoran.
Thermal recording was performed in the same manner as in Example 1 except that pentyl) ethylamino-6-methyl-7-anilinofluorane was replaced with oxalic acid-di (p-methylbenzyl) ester instead of 2-benzyloxynaphthalene. I got a body.

Example 9 In the preparation of Solution A, 3-diethylamino-6-methyl-7-anilinofluoran was replaced with 2-diethylamino-6-methyl-7-anilinofluoran instead of 3-di-n-butylamino-6-methyl-7-anilinofluoran. A heat-sensitive recording material was obtained in the same manner as in Example 1, except that oxalic acid-dibenzyl ester was used instead of benzyloxynaphthalene.

Example 10 In preparing solution A, 3-di-n-pentylamino-6-methyl-7-anilinofurane was used instead of 3-di-n-butylamino-6-methyl-7-anilinofluoran. A thermosensitive recording material was obtained in the same manner as in Example 1, except that p-benzylbiphenyl was used instead of 2-benzyloxynaphthalene as silane.

Example 11 In the preparation of solution A, 1,2-bis (phenoxy) ethane was used instead of 2-benzyloxynaphthalene, and in the preparation of solution B, 4-i-propoxy-4 was used instead of benzyl p-hydroxybenzoate. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that '-hydroxy-diphenylsulfone was used.

Example 12 In the preparation of solution A, 1,2-bis (3-methylphenoxy) ethane was used in place of 2-benzyloxynaphthalene,
In the preparation of solution B, 3- (p-hydroxyphenyl)-
Except for using 20 parts instead of 15 parts of 1,1,3-trimethyl-5-indanol and 5 parts of 4-i-propoxy-4-hydroxy-diphenylsulfone instead of 10 parts of benzyl p-hydroxybenzoate. Example 1
In the same manner as in the above, a thermosensitive recording medium was obtained.

Example 13 In the preparation of Solution B, 5 parts of p-hydroxybenzoic acid benzyl ester was used instead of 10 parts of 4,4'-thiobis (6-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 5 parts of (t-butylphenol-m-cresol) was used.

Example 14 In the preparation of Solution B, 5 parts and 2,2'-methylenebis (4-methyl-6-t-butylphenol) were used instead of 10 parts of benzyl p-hydroxybenzoate, except that A thermosensitive recording medium was obtained in the same manner as in Example 1.

Example 15 Preparation of Solution B, except that 10 parts of p-hydroxybenzoic acid benzyl ester and 5 parts of 4,4'-butylidenebis (6-tert-butylphenol-m-cresol) were used instead of 10 parts of benzyl p-hydroxybenzoate. A thermosensitive recording medium was obtained in the same manner as in Example 1.

Example 16 In the preparation of solution B, 5 parts of p-hydroxybenzoic acid benzyl ester and 5 parts of a magnesium salt of 2,2'-methylenebis (4,6-di-t-butylphenyl) phosphate were used instead of 10 parts of benzyl ester of p-hydroxybenzoic acid. A heat-sensitive recording material was obtained in the same manner as in Example 1 except for using the same.

Example 17 In the preparation of solution B, 5 parts of p-hydroxybenzoic acid benzyl ester was replaced with 5 parts of 1,3,5-tris (3,3
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 5 parts of 5-di-t-butyl-4-hydroxybenzyl) isocyanuric acid was used.

Example 18 In the preparation of Solution B, 5 parts of 1,3,5-tris (3,3) was used instead of 10 parts of benzyl p-hydroxybenzoate.
5-di-t-butyl-4-hydroxybenzyl) -2,
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 5 parts of 4,6-trimethylbenzene was used.

Example 19 In the preparation of solution B, the color former 3- (p-hydroxyphenyl) -1,1,3-trimethyl-5-indanol (m
p. (195-196 ° C) instead of 194-19
3- (p-hydroxyphenyl) -1,1,3-
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that trimethyl-5-indanol was used.

Example 20 In the preparation of solution B, the color former 3- (p-hydroxyphenyl) -1,1,3-trimethyl-5-indanol (m
p. (195-196 ° C) instead of 197.5-
3- (p-hydroxyphenyl) -1, 198.5 ° C.
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 1,3-trimethyl-5-indanol was used.

Comparative Example 1 In the preparation of solution A, 3 was used in place of the basic dye 3-di-n-butylamino-6-methyl-7-anilinofluoran.
-N-ethyl-Np-tolylamino-6-methyl-7
Anilinofluorane, stearic acid amide in place of 2-benzyloxynaphthalene as a color former, B
In the liquid preparation, the color formers 3- (p-hydroxyphenyl) -1,1,3-trimethyl-5-indanol and p
-Instead of benzyl hydroxybenzoate 3-
A heat-sensitive recording material was obtained in the same manner as in Example 1, except that 25 parts of (p-hydroxyphenyl) -1,1,3-trimethyl-5-indanol (mp. 195-196 ° C.) alone was used.

Comparative Example 2 In the preparation of solution A, 3 was used in place of the basic dye 3-di-n-butylamino-6-methyl-7-anilinofluoran.
-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran, stearic acid amide in place of 2-benzyloxynaphthalene as a color improver, and 3- Instead of (p-hydroxyphenyl) -1,1,3-trimethyl-5-indanol (mp. 195-196 ° C) and benzyl p-hydroxybenzoate, 3- (p-hydroxy A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 25 parts of (phenyl) -1,3,3-trimethyl-5-indanol was used. Evaluation of thermal recording medium

The 21 kinds of heat-sensitive recording media thus obtained were recorded by Matsushita Simulator MF-1 (applied voltage: 16 V, pulse width: 2 ms). For the obtained recorded image, the color density of the recorded image and the background density of the blank portion were measured with a Macbeth reflection densitometer (RD-914, manufactured by Macbeth), and the recording was performed after performing the following test method. The density of the image and the degree of discoloration of the background were evaluated, and the results are shown in Table 1.

[Heat Resistance Test] After the recording paper obtained in the color development test was allowed to stand at 60 ° C. for 16 hours, the density of the color image and the background density of the white paper were measured. [Light Resistance Test] Light was irradiated for 12 hours using a fade meter (manufactured by Suga Test Instruments Co., Ltd.) using an ultraviolet carbo-arc lamp as a light source, and the discoloration of the sheet was visually evaluated. ○: no yellowing, Δ: slight yellowing, ×: large yellowing

[0063]

[Table 1]

[0064]

As is clear from the results shown in Table 1, the heat-sensitive recording material obtained in the present invention was a heat-sensitive recording material having excellent color development sensitivity, storage stability of a recorded image, and light resistance of a background portion. .

Continued on the front page (72) Inventor Hiromi Kawachi 1-26-11 Hisamatsudai, Fukuyama City, Hiroshima Prefecture (72) Inventor Shuya Sekiyama 2-15-23 Higashiizumioka, Toyonaka City, Osaka Prefecture Maison de Archamp 402 (72) Inventor Uchida Tadashi 1049-115 F-term (reference) Fukuki, Heigun-cho, Ikoma-gun, Nara Prefecture 2H026 AA07 BB15 BB25 BB30 BB39 DD02 DD12 DD45 DD46 DD53

Claims (3)

[Claims] 1. A heat-sensitive recording medium provided with a heat-sensitive recording layer containing a colorless or light-colored basic dye and a colorant capable of forming a color upon contact with the dye, wherein 3- (p) is used as the colorant.
-Hydroxyphenyl) -1,1,3-trimethyl-5
Using a mixture of indanol and at least one phenolic compound represented by the general formulas [1] to [7], and using 3-di-n-butylamino-6-methyl-
7-anilinofluoran, 3-di-n-pentylamino-6-methyl-7-anilinofluoran, 3- (N-i
-Pentyl) ethylamino-6-methyl-7-anilinofluoran and 3-diethylamino-6-methyl-7-
Using at least one compound selected from the group consisting of anilinofluoran, and further using oxalic acid as a color improver
Dibedyl ester, oxalic acid-di (p-methylbenzyl) ester, 2-benzyloxynaphthalene, m-terphenyl, p-benzylbiphenyl, 4- (p-methylphenoxy) biphenyl, 1,2-bis (phenoxy) ethane And at least one compound selected from the group consisting of 1,2-bis (3-methylphenoxy) ethane and a thermosensitive recording layer. Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image 2. A preservative improver having a general formula [8] to [1]
2. The heat-sensitive recording material according to claim 1, wherein at least one compound selected from the group consisting of a hindered phenol compound of 2) and / or a hindered phenol phosphate compound of the general formula [13] is contained in the heat-sensitive recording layer. Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image 3. The color former having a melting point of 194 to 199 ° C.
The heat-sensitive recording material according to claim 1, wherein the thermosensitive recording material is-(p-hydroxyphenyl) -1,1,3-trimethyl-5-indanol.