JPH09268183A - Benzotriazole compound and heat-sensitive recording material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new benzotriazole compound useful as an ultraviolet light absorber. SOLUTION: This compound is shown by formula I (R is a 1-8C alkyl) such as 1,4-bis [2-hydroxy-3-(2H-benzotriazol-2-yl)-5-methylphenylsulfonyl]piperazine. The compound of formula I is obtained by reacting an acid chloride of formula II with piperazine in the presence of a base (e.g. triethylamine) in an inert solvent (e.g. chloroform) under cooling with ice or at a room temperature. The compound of formula I is added to at least one of a heat-sensitive recording layer or a protecting layer to give a heat-sensitive recording material improved in light resistance of a recording part and a nonrecording part without damaging basic characteristics of the recording material. A heat-sensitive material excellent in light resistance of a recordable part and an unrecordable part, chemical resistance such as plasticizer resistance, oil resistance and solvent resistance and recording and traveling properties is obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel benzotriazole compound, and a heat-sensitive recording which uses the same as an ultraviolet absorber to improve the light resistance of a recorded portion and an unrecorded portion without deteriorating the characteristics of the heat-sensitive recording material. It is about the body.

[0002]

2. Description of the Related Art A heat-sensitive recording material in which a plurality of color-forming substances are brought into contact with each other by heat to obtain a recorded image is well known. Since such a thermal recording medium is relatively inexpensive, the recording device is compact, and its maintenance is easy, it is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields.

Generally, a thermosensitive recording medium has a drawback that when exposed to sunlight or room light for a long period of time, the background portion gradually turns yellow and the recorded image is discolored. As part of expanding the fields of use of thermal recording media, for example, POS (point
There is a thermal recording label for the system, but with the expansion of the system, it has been used for a long time in addition to the label for food, which has completed its mission in a short period as before. The use as tag paper or handy terminal paper for collection and delivery, which is often handled outdoors, is increasing. However, in such applications, it is often exposed to indoor light or sunlight for a long period of time, and the effect of this is that the recorded image on the thermosensitive recording material may fade or the background part may turn yellow, resulting in a product image. Will be significantly damaged.

For this reason, there is a strong demand for a heat-sensitive recording material which is excellent in light resistance with little fading of recorded images and yellowing of the background even when exposed to room light or sunlight for a long time. Further, the heat-sensitive recording material for tag paper or handy terminal paper as described above is also required to have resistance to a recorded image against chemicals such as plasticizers, oils or solvents as in the case of heat-sensitive labels for foods.

Conventionally, a method of adding a benzotriazole compound to a heat-sensitive recording layer for the purpose of improving the light resistance of the heat-sensitive recording material is disclosed in JP-B-53-23205 and JP-A-55-205.
55891, JP-A-63-307981, JP-A-3.
No. 23986, JP-A-5-8545, and the like. Further, for the purpose of improving the chemical resistance of the heat-sensitive recording material, a method of adding a benzotriazole compound to the heat-sensitive recording layer is disclosed in JP-A-58-87093 and JP-A-63-1.
It is proposed in Japanese Patent No. 5783.

Further, a method of providing a protective layer on the heat-sensitive recording layer for the purpose of improving the chemical resistance of the heat-sensitive recording material is disclosed in JP-A-54.
-128347, Jikken Sho 59-9909, Jikkou 6
No. 2-26216 and many others have been proposed. Further, for the purpose of improving the light resistance of the thermosensitive recording medium, a method of adding a finely pulverized benzotriazole compound to a protective layer formed on the recording layer is disclosed in JP-A-60-107388.
JP-A-60-112487 and JP-A-61-193.
It is proposed in Japanese Patent No. 883.

However, the previously proposed 2-
If a benzotriazole compound such as (2'-hydroxy-5'-methylphenyl) benzotriazole is contained in the thermosensitive recording layer to obtain sufficient light resistance, the absorption efficiency of ultraviolet rays, in other words, the shielding of ultraviolet rays. In terms of efficiency, it is necessary to add a relatively large amount of these compounds, and therefore, there is a drawback that the basic characteristics as a thermal recording medium are impaired, such as the occurrence of background fog when placed in a high temperature environment.
Further, the effect of improving the chemical resistance obtained by adding such a benzotriazole compound to the heat-sensitive recording layer is not as great as the effect obtained by forming the protective layer and is not satisfactory.

On the other hand, a method of adding a benzotriazole compound to the protective layer formed on the heat-sensitive recording layer is also possible.
When a conventionally proposed compound such as 2- (2'-hydroxy-5'-methylphenyl) benzotriazole is used, it may melt at the time of recording due to the relatively low melting point of the compound, resulting in a thermal head. Sticking occurs with the protective layer and a uniform recorded image cannot be obtained,
Further, there is a problem that these compounds are eluted by chemicals and impair the original barrier function of the protective layer, resulting in deterioration of chemical resistance of the recorded image.

[0009]

In view of such circumstances, the object of the present invention is to provide a novel compound which can be used as an ultraviolet absorber, and a basic compound of the above-mentioned thermosensitive recording medium using the compound as an ultraviolet absorber. To provide a heat-sensitive recording material in which the light resistance of the recorded part and the unrecorded part is improved without damaging, and the light resistance of the recorded part and the unrecorded part is excellent, and the plasticizer resistance, oil resistance, solvent resistance, etc. It is to provide a thermal recording material having excellent chemical resistance and recording runnability.

[0010]

The present invention provides a benzotriazole compound represented by the general formula (1) and a support,
In a thermosensitive recording layer comprising an electron-donating compound and an electron-accepting compound, and a protective layer if necessary, a benzoate represented by the general formula (1) in at least one of the thermal recording layer and the protective layer. The present invention relates to a thermosensitive recording medium containing at least one triazole compound.

[0011]

Embedded image [Wherein, R represents an alkyl group of C ₁ -C _8. ]

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The benzotriazole compound of the present invention represented by the general formula (1) can be easily synthesized, for example, by the following typical methods. That is, the acid chloride represented by the general formula (2) and piperazine are prepared in the presence of a base such as triethylamine or pyridine as a neutralizing agent for hydrogen chloride produced, in an inert solvent such as ether, chloroform or dichloromethane. It can be obtained by reacting with ice-cooling at room temperature.

[0013]

Embedded image [Wherein, R represents an alkyl group of C ₁ -C _8. ]

The compound represented by the general formula (2) is preferably used in an amount of 2 mol or more per 1 mol of piperazine. Of the alkyl groups represented by R, an alkyl group of C _{1 to 4} are particularly preferred.

The present invention provides a thermosensitive recording layer containing an electron-donating compound and an electron-accepting compound on a support, and a protective layer if necessary, in which at least the thermosensitive recording layer and the protective layer are provided. By containing at least one of the specific benzotriazole compounds represented by the general formula (1) on the other hand, the light resistance of the recorded area and the unrecorded area becomes remarkable as compared with the conventionally proposed benzotriazole compounds. It will be improved. Further, even when the above-mentioned specific benzotriazole compound is blended in the recording layer, the background fog in a high temperature environment is extremely small. Moreover, since such a specific benzotriazole compound is hardly dissolved in solvents such as plasticizers, oils and organic solvents, when it is used in the protective layer, even if the protective layer surface comes into contact with these solvents, the elution of the ultraviolet absorber The barrier function is not deteriorated due to, and the chemical resistance is also improved. In addition, sticking and head residue due to melting do not occur at the time of recording with the thermal head, and an improved effect of excellent recording running performance can be obtained.

In the present invention, if the specific benzotriazole compound is contained in either the heat-sensitive recording layer or the protective layer, a desired effect can be obtained. Of course, both the recording layer and the protective layer are obtained. Can be included in
It is also possible to contain the protective layer only in the recording layer of the thermosensitive recording medium. In addition, in terms of the efficiency of blocking ultraviolet rays, it is better to mix the protective layer than the recording layer.

Specific examples of the benzotriazole compound represented by the general formula (1) include 1,4-bis [2-hydroxy-3- (2H-benzotriazol-2-yl) -5-methylphenylsulfonyl. ] Piperazine,
1,4-bis [2-hydroxy-3- (2H-benzotriazol-2-yl) -5-ethylphenylsulfonyl] piperazine, 1,4-bis [2-hydroxy-3-
(2H-benzotriazol-2-yl) -5-isopropylphenylsulfonyl] piperazine, 1,4-bis [2-hydroxy-3- (2H-benzotriazol-
2-yl) -5-sec-butylphenylsulfonyl]
Piperazine, 1,4-bis [2-hydroxy-3- (2
H-benzotriazol-2-yl) -5-tert-
Butylphenylsulfonyl] piperazine, 1,4-bis [2-hydroxy-3- (2H-benzotriazole-
2-yl) -5-tert-amylphenylsulfonyl] piperazine, 1,4-bis [2-hydroxy-3-
(2H-benzotriazol-2-yl) -5- (1,
1,3,3-Tetramethylbutyl) phenylsulfonyl]
Examples thereof include piperazine. Of course, it is not limited to these, and two or more kinds may be used in combination as required.

The benzotriazole compound is preferably finely pulverized and added to the heat-sensitive recording layer or the protective layer. As a method of fine pulverization, generally water is used as a dispersion medium and a dispersant, an antifoaming agent or the like is added. Examples of the method include adding an agent as needed and dispersing with a stirring / crushing machine such as a ball mill, attritor, or sand mill. The finely pulverized benzotriazole compound preferably has an average particle size of 2.0 μm or less, and in particular, by setting it to 0.5 μm or less, not only the absorption efficiency of ultraviolet rays is significantly improved, but also that having this particle size is used as a protective layer. When added, the recorded image is hardly concealed, so that a clear recorded image can be obtained, and in addition, since the film forming property of the protective layer is improved, an excellent effect of improving chemical resistance can be obtained.

The heat-sensitive recording method utilizing the color reaction between the electron-donating compound and the electron-accepting compound to which the present invention is applied includes, for example, a combination of a leuco dye and a color former, a combination of a diazonium salt and a coupler. The combination of an organic acid salt of a transition element such as iron and a chelating agent, the combination of an aromatic isocyanate compound and an imino compound, and the like. Since the recording sensitivity is also excellent, the heat-sensitive recording material utilizing the color reaction between the leuco dye and the color-developing agent will be described in detail below.

As the leuco dye, various known leuco dyes can be used, and specific examples thereof include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide and 3-cyclohexylamino-6. -Chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, rhodamine (o-chloroanilino) lactam, 3- (N-ethyl-p-toluidino) -7-methylfluorane, 3-diethylamino-6. , 8-Dimethylfluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-
Methyl-N-cyclohexyl) amino-6-methyl-7
-Anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-di-n-butylamino-6-methyl-7-anilinofluorane, 3-di-n
-Pentylamino-6-methyl-7-anilinofluorane, 3-di-n-butylamino-7- (o-chlorophenylamino) fluorane, 3- (N-ethyl-p-toluidino) -6-methyl- 7-anilinofluoran, 3-
Diethylamino-7- (m-trifluoromethylanilino) fluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7 -Anilinofluorane, 3-dimethylamino-6-methyl-7-anilinofluorane, 3-di-n-butylamino-6-methyl-7-m-toluidinofluorane, 3- (N- Ethyl-N-ethoxypropyl) amino-6-methyl-7-
Anilinofluoran, 3- (N-methyl-NNn-propyl) amino-6-methyl-7-anilinofluoran,
3,3-bis [1- (4-methoxyphenyl) -1-
(4-Dimethylaminophenyl) ethylene-2-yl]
-4,5,6,7-tetrachlorophthalide, 3- (4-dimethylaminophenyl) amino-5,7-dimethylfluorane, 3- (4-dibutylaminophenyl) amino-
6-methyl-7-chlorofluorane, 3,3-bis (4
-Diethylamino-2-ethoxyphenyl) -4-azaphthalide and the like. Of course, it is not limited to these, and two or more kinds may be used in combination as required. The amount of the leuco dye used is not particularly limited, but is 5 to 40% by weight based on the total solid content of the heat-sensitive recording layer.
The degree is preferred.

Various known coloring agents can be used in combination with the leuco dye, and specific examples thereof include 4,4 '.
-Isopropylidenediphenol, 1,1-bis (4-
Hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane,
4,4'-dihydroxydiphenyl sulfide, benzyl 4-hydroxybenzoate, 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, bis (3- Allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4′-methyldiphenylsulfone, 4-hydroxyphenyl-4′-benzyloxyphenylsulfone, 3,4-dihydroxyphenyl-4′-methylphenylsulfone, bis (4 -Hydroxyphenylthioethoxy) methane, 1,4-bis [α
-Methyl-α- (4'-hydroxyphenyl) ethyl]
Phenolic compounds such as benzene, 1,3-bis [α-methyl-α- (4′-hydroxyphenyl) ethyl] benzene, di (4-hydroxy-3-methylphenyl) sulfide, N, N′-di- Thiourea compounds such as m-chlorophenyl thiourea, zinc p-chlorobenzoate, 4
Aroma such as zinc- (2-p-methoxyphenoxyethoxy) salicylate, zinc 4- [3- (p-tolylsulfonyl) propoxy] salicylate, and zinc 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylate. Zinc salt of group carboxylic acid, 4,4'-bis (p-
Organic acid substances such as tolylsulfonylurea) diphenylmethane and the like can be mentioned. Among them, 4-hydroxy-4 '
-Isopropoxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone or 2,4'-
When dihydroxydiphenyl sulfone is used, a thermosensitive recording medium having particularly excellent storability of recorded images can be obtained, and therefore it is preferably used.

The use ratio of the leuco dye and the color developing agent is appropriately selected according to the type of the leuco dye or the color developing agent to be used and is not particularly limited, but generally 100 parts by weight of the leuco dye. 50 to 500 parts by weight, and preferably about 100 to 300 parts by weight of the coloring agent is used. Further, the use ratio of the specific benzotriazole compound in the heat-sensitive recording layer is not particularly limited, but generally 10 to 500 parts by weight, preferably 20 to 200 parts by weight based on 100 parts by weight of the leuco dye. It is about part by weight.

Further, the heat-sensitive recording layer may contain a sensitizer for increasing the recording sensitivity and a storability improving agent for improving the storability of the recorded image with time. Specific examples of the sensitizer include stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, ethylenebisstearic acid amide, methylenebisstearic acid amide, and N.
-Methylol stearamide, dibenzyl terephthalate, p-benzyloxybenzoate benzyl, 2-naphthylbenzyl ether, m-terphenyl, dibenzyl oxalate, oxalate-di-p-methylbenzyl, oxalate-di-p- Chlorobenzyl, p-benzylbiphenyl, di (p-methoxyphenoxyethyl) ether,
1,2-di (3-methylphenoxy) ethane, 1,2-di (4-methylphenoxyethane), 1,2-di (4-methoxyphenoxy) ethane, 1,2-diphenoxyethane, 1- ( 4-methoxyphenoxy) -2- (3-methoxyphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p
-Biphenyl-p-tolyl ether, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1
-Isopropylphenyl-2-phenylethane and the like.

Specific examples of the storability improver include 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol),
1,1,3-tris (2-methyl-4-hydroxy-5-
Cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,4′-thiobis (3-methyl-6)
-Tert-butylphenol), 4,4'-dihydroxy-3,3 ', 5,5'-tetramethyldiphenylsulfone, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2- Bis (4-hydroxy-3,
Hindered phenol compounds such as 5-dimethylphenyl) propane, 1,4-diglycidyloxybenzene,
4,4'-diglycidyloxydiphenyl sulfone, 4-
Benzyloxy-4 ′-(2-methylglycidyloxy) diphenyl sulfone, diglycidyl terephthalate,
Epoxy compounds such as cresol novolac type epoxy resin, phenol novolac type epoxy resin and bisphenol A type epoxy resin, and other N, N'-di-2-naphthyl-p-phenylenediamine, 2,2'-methylenebis (4,6- Sodium or polyvalent metal salt of di-tert-butylphenyl) phosphate, bis (4-ethyleneiminocarbonylaminophenyl) methane and the like can be mentioned. Among them, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane is preferably used because it has an excellent effect of improving water resistance and is less likely to cause background fog. The amount of the sensitizer and the storability improver used is not particularly limited, but it is generally desirable to adjust the amount within the range of 400 parts by weight or less relative to 100 parts by weight of the color developing agent.

The coating liquid for heat-sensitive recording layer containing these substances is
Generally, water is used as a dispersion medium, additives such as a dispersant and an antifoaming agent are added if necessary, and these substances are dispersed together or separately by a stirring / grinding machine such as a ball mill, attritor, or sand mill. It is prepared by mixing and stirring the materials.

In the coating liquid for the heat-sensitive recording layer, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, etc. are usually used as a binder.
Carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / At least one kind of acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, urea resin, melamine resin, amide resin, polyurethane resin, etc. is used in an amount of about 10 to 40% by weight based on the total solid amount of the heat-sensitive recording layer. It is preferably blended in the range of 15 to 30% by weight. Further, various auxiliary agents can be added to the coating liquid as needed, and examples thereof include surfactants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate / sodium salt, and fatty acid metal salt. , Waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, inorganic pigments such as kaolin, clay, talc, calcium carbonate, aluminum hydroxide, calcined kaolin, titanium dioxide, and amorphous silica. Styrene microballs, nylon powder, polyethylene powder,
A urea / formalin resin filler, an organic pigment such as raw starch particles, an antifoaming agent, a fluorescent dye, a coloring dye, and the like are appropriately added.

The method for forming the heat-sensitive recording layer is not particularly limited, and may be any suitable coating method such as air knife coating, varibar coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, die coating and the like. Apply the heat sensitive recording layer coating liquid on the support.
It is formed by a method such as drying. The coating amount of the coating liquid is not particularly limited, usually 2~12g / m ² by dry weight, it is preferably adjusted in the range of about 3 to 10 g / m ^2. The support is appropriately selected from paper (acidic paper, neutral paper), plastic film, synthetic paper, non-woven fabric, metal vapor deposition sheet and the like.

When a specific benzotriazole compound is contained in the protective layer, its content is not particularly limited, but it is 1 to 5 relative to the total solid content of the protective layer.
The range of 0% by weight is preferable, and more preferably 10 to 40.
% By weight. When the content of such a specific benzotriazole compound is less than 1% by weight based on the total solid content of the protective layer, the light resistance of the recorded image is deteriorated, and when it exceeds 50% by weight, the film forming property of the protective layer is deteriorated. The chemical resistance of the image may be reduced.

The protective layer further contains a water-soluble or water-dispersible binder, and as the binder, various binders used in the above-mentioned heat-sensitive recording layer are used. Among them, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol and silicon-modified polyvinyl alcohol are
It is preferably used because it has an excellent effect as a protective layer. Among them, acetoacetyl group-modified polyvinyl alcohol is preferable because it can easily enhance the chemical resistance and the water resistance of the protective layer. The acetoacetyl group-modified polyvinyl alcohol is an acetoacetic acid ester of polyvinyl alcohol having a polymerization degree of about 200 to 2000. The acetoacetic acid esterification of polyvinyl alcohol may be carried out by adding diketene to the polyvinyl alcohol resin or transesterifying the acetoacetic acid ester. The content of the binder is preferably about 15 to 80% by weight based on the total solid content of the protective layer.

In the protective layer, in order to improve printability and sticking, for example, calcium carbonate, zinc oxide,
Inorganic pigments such as aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, talc, kaolin, clay, colloidal silica and organic pigments such as styrene microballs, nylon fillers, urea / formalin resin fillers, raw starch particles, etc. Can be blended as needed. It should be noted that it is desirable to adjust the amount of such a pigment to be blended in the range of 5 to 500 parts by weight with respect to 100 parts by weight of the binder. Furthermore, zinc stearate, calcium stearate, polyethylene wax, carnauba wax,
Paraffin wax, ester wax, and other lubricants, dioctyl sodium sulfosuccinate and other surfactants (dispersants, wetting agents), defoamers, and various auxiliaries such as water-soluble polyvalent metal salts such as potassium alum and aluminum acetate It can also be added. Further, a curing agent such as glyoxal, boric acid, dialdehyde starch, or an epoxy compound can be used to further improve water resistance.

The method for preparing the coating liquid for the protective layer is not particularly limited, and generally, water is used as a dispersion medium, and an aqueous binder, the above-mentioned specific benzotriazole compound, and pigments and lubricants which are added as necessary. Are prepared by mixing. The method for forming the protective layer is not particularly limited, and for example, the protective layer coating liquid is applied onto the heat-sensitive recording layer by various appropriate coating methods as described above and dried. Further, if the coating amount of the protective layer coating liquid exceeds 15 g / m ² on a dry weight basis, the recording sensitivity of the thermal recording material may decrease, so it is generally 0.5 to 15 g / m ² , preferably 1 to It is adjusted within the range of about 7 g / m ² . If necessary, a protective layer may be provided on the back side of the thermosensitive recording medium to further improve the storability. Further, an undercoat layer may be provided between the support and the heat-sensitive recording layer, smoothing treatment such as super calendering may be applied after coating each layer, or an adhesive label may be applied to the back surface of the recording material to form an adhesive label. Various known techniques in the field of producing a heat-sensitive recording material can be added as necessary, such as providing a magnetic recording layer, a pigment coating layer for printing, and a thermal transfer recording layer.

[0032]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, "part" and "%" in an example show "weight part" and "weight%", respectively, unless there is particular notice.

Synthesis Example 1 1,4-bis [2-hydroxy-3- (2H-benzoto)
Lyazol-2-yl) -5-methylphenylsulfoni
Le] piperazine 2-hydroxy-3-(2H-benzotriazol -2
-Yl) -5-methylphenylsulfonyl chloride 5
A suspension of 0 g and 200 ml of chloroform was added to a suspension of 6.6 g of piperazine in chloroform (50
ml) solution was added dropwise over 1 hour, and the mixture was stirred at the same temperature for 1 hour. Then, with stirring, at the same temperature, triethylamine 1 was added.
A solution of 4.0 g of chloroform (50 ml) was added dropwise over about 30 minutes, and the mixture was further stirred at the same temperature for 1 hour. The white precipitate formed was collected by filtration, washed with chloroform under reflux, and dried to obtain 43.8 g of white powder having a decomposition temperature of 382 to 384 ° C. IR
By measurement (KBr tablet method), 3448 cm ^-1 (derived from hydroxyl group), 2879 cm ^-1 and 2926 cm ^-1 (derived from methylene group), and 1352 cm ^-1 , 1339 cm ^-1 and 1158 cm ^-1 (derived from sulfonyl group) ) Characteristic absorption of 1,4-bis [2-hydroxy-3-
It was confirmed to be (2H-benzotriazol-2-yl) -5-methylphenylsulfonyl] piperazine. The yield was 86.6%.

Example 1 Preparation of Solution A 3-di-n-butylamino-6-methyl-7-anilinofluorane 10 parts, 1,2-bis (3-methylphenoxy) ethane 20 parts, methylcellulose 5 % Aqueous solution 10
Parts and 50 parts of water were pulverized with a sand mill until the average particle size reached 1.2 μm.

Preparation of solution B A composition consisting of 20 parts of 4-hydroxy-4'-isopropoxydiphenyl sulfone, 10 parts of a 5% aqueous solution of methylcellulose, and 30 parts of water was sand-milled until the average particle size reached 1.2 μm. Crushed.

Preparation of solution C 1,4-bis [2-hydroxy-3- (2H-benzotriazol-2-yl) -5-methylphenylsulfonyl] piperazine 10 parts, 5% aqueous solution of methylcellulose 5 parts, and water A composition consisting of 15 parts was pulverized with a sand mill until the average particle size became 0.4 μm.

Formation of thermosensitive recording layer 90 parts of solution A, 60 parts of solution B, 10 parts of polyvinyl alcohol
% 80% aqueous solution and 35 parts calcium carbonate are mixed and stirred, and the coating solution is applied to one side of a high-quality paper of 60 g / m ² such that the coating amount after drying is 6 g / m ² and dried to obtain heat. A recording layer was formed.

Formation of protective layer 30 parts of C liquid, 125 parts of 10% aqueous solution of polyvinyl alcohol modified with acetoacetyl group [trade name: Gocefimer Z-200, manufactured by Nippon Synthetic Chemical Industry], kaolin [trade name:
UW-90, manufactured by EMC] 29 parts, a coating solution obtained by mixing and stirring a composition consisting of 6 parts of a 30% aqueous zinc stearate dispersion and 30 parts of water is dried on the thermosensitive recording layer. Was coated and dried to a coating amount of 5 g / m ^2, and then supercalendered to obtain a heat-sensitive recording material.

Example 2 In the preparation of the liquid C of Example 1, 1,4-bis [2-hydroxy-3- (2H-benzotriazol-2-yl)-
Examples except that 1,4-bis [2-hydroxy-3- (2H-benzotriazol-2-yl) -5-tert-butylphenylsulfonyl] piperazine was used instead of 5-methylphenylsulfonyl] piperazine. 1
A thermosensitive recording medium was obtained in the same manner as described above.

Example 3 In the preparation of solution A of Example 1, instead of 3-di-n-butylamino-6-methyl-7-anilinofluorane,
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 3-diethylamino-7- (m-trifluoromethylanilino) fluorane was used.

Example 4 In the preparation of solution B of Example 1, 4-hydroxy-4'-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that bis (3-allyl-4-hydroxyphenyl) sulfone was used instead of isopropoxydiphenylsulfone.

Example 5 In the preparation of solution B of Example 1, 4-hydroxy-4'-
2,4 'instead of isopropoxydiphenyl sulfone
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that dihydroxydiphenyl sulfone was used.

Example 6 In the preparation of solution B of Example 1, 4-hydroxy-4'-
4,4 'instead of isopropoxydiphenyl sulfone
A thermal recording material was obtained in the same manner as in Example 1 except that isopropylidenediphenol was used.

Example 7 In the same manner as in Example 1 except that the liquid C was prepared in the same manner as in Example 1, except that the average particle size was adjusted to 1.5 μm instead of the average particle size was 0.4 μm. A thermosensitive recording material was obtained.

Example 8 In the formation of the thermosensitive recording layer of Example 1, 60 parts of C liquid was further added to the thermosensitive recording layer coating liquid to form the thermosensitive recording layer,
On the other hand, a thermosensitive recording medium was obtained in the same manner as in Example 1 except that the protective layer was formed without using the liquid C in the formation of the protective layer.

Comparative Example 1 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that the liquid C was not used in the formation of the protective layer in Example 1.

Comparative Example 2 In the preparation of the liquid C of Example 1, 1,4-bis [2-hydroxy-3- (2H-benzotriazol-2-yl) was used.
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 2- (2'-hydroxy-5'-methylphenyl) benzotriazole was used instead of -5-methylphenylsulfonyl] piperazine.

The thermal recording material thus obtained was subjected to the following evaluation tests, and the results are shown in Table 1. [Coloring property] Using a heat-sensitive evaluation machine [trade name: TH-PMD, manufactured by Okura Electric Co., Ltd.], applied energy 0.45 mj / dot
Each thermosensitive recording medium is made to develop color by using a Macbeth densitometer [RD-914
Type, manufactured by Macbeth Co., Ltd.] in visual mode.

[Sharpness of Recorded Image] The sharpness (image quality) of the recorded image obtained by the evaluation of the color developability was visually determined. Evaluation Criteria A: The recorded image is very clear. ◯: The recorded image is clear. X: The recorded image is slightly unclear.

[Lightfastness] The thermosensitive recording material recorded in the above evaluation of color development was set under the conditions of light source: xenon, 63 ° C., 50% RH (trade name: SUNSHIN).
EX ENONLONG LIFE WEATHER
METER (manufactured by Suga Test Instruments Co., Ltd.) for 24 hours, and then the density of the unrecorded portion and the recorded image is measured using a Macbeth densitometer, the unrecorded portion is in the blue filter mode and the recorded image is in the visual mode. It was measured.

[Plasticizer resistance] Wrap film [Product name: KMA-on a polycarbonate pipe (40 mmφ pipe)]
W, manufactured by Mitsui Toatsu Kagaku Co., Ltd.] is wound in three layers, the thermosensitive recording medium recorded in the above evaluation of color development is placed thereon, and a wrap film is further wound in three layers thereon, and the wrap film is placed at 40 ° C. for 24 hours.
The recorded image density after standing for a period of time was measured with a Macbeth densitometer (visual mode) to evaluate the plasticizer resistance.

[Oil resistance] Edible oil was applied onto the thermosensitive recording medium recorded in the above evaluation of color developability, and the recorded image density after standing at room temperature for 8 hours was measured with a Macbeth densitometer (visual mode), The oil resistance was evaluated.

[Solvent resistance] The surface of the heat-sensitive recording material before recording was wiped with a gauze soaked with ethanol, and the fog density was measured with a Macbeth densitometer (visual mode) to evaluate the solvent resistance.

[Head Matching Property] The soiling condition (head residue) of the thermal head after continuous recording of 200 mm in the evaluation of the color developing property was visually evaluated as follows. Evaluation criteria ⊚: No head shavings at all. ◯: There is some head shavings, but there is no practical problem. X: Some amount of head shavings.

[0055]

[Table 1]

Example 9 A coating liquid was prepared in the same manner as in Example 1 except that 60 parts of C liquid was further added to the coating liquid for the thermal recording layer in the formation of the thermal recording layer of Example 1. The coating solution was applied and dried on one surface of a high-quality paper of 60 g / m ² so that the coating amount after drying was 6 g / m ^2, and then supercalendering was performed to obtain a heat-sensitive recording material having no protective layer.

Comparative Example 3 In the liquid C of Example 9, 1,4-bis [2-hydroxy-3- (2H-benzotriazol-2-yl) -5 was used.
-Methylphenylsulfonyl] piperazine,
A thermosensitive recording medium having no protective layer was obtained in the same manner as in Example 9 except that 2- (2'-hydroxy-5'-methylphenyl) benzotriazole was used.

The following two evaluation tests were conducted on the thus obtained two types of thermal recording materials, and the results are shown in Table 2. [Coloring property] Evaluation was performed in the same manner as in the above method. [Light resistance] Evaluation was performed in the same manner as in the above method except that the processing time of the weather meter was 16 hours. [Heat resistance of unrecorded area] The thermosensitive recording medium before recording was left in a dryer at 80 ° C. for 24 hours, and then the density was measured with a Macbeth densitometer (visual mode).

[0059]

[Table 2]

[0060]

As is clear from the results shown in Table 1, the thermosensitive recording medium of the present invention is excellent not only in light resistance of recorded areas and unrecorded areas but also in plasticizer resistance, oil resistance and solvent resistance. It was a thermal recording material that also had excellent head matching properties. Further, as is clear from the results in Table 2, the heat-sensitive recording material of the present invention was a heat-sensitive recording material which did not cause fog even when exposed to a high temperature environment and was excellent in light resistance.

Claims (3)

[Claims] 1. A benzotriazole compound represented by the general formula (1). Embedded image [Wherein, R represents an alkyl group of C ₁ -C _8. ] 2. A thermosensitive recording layer comprising an electron-donating compound and an electron-accepting compound on a support, and a protective layer if necessary, which is provided on at least one of the thermal recording layer and the protective layer. A thermosensitive recording medium comprising at least one benzotriazole compound represented by the general formula (1). 3. An electron-accepting compound is 4-hydroxy-
4'-isopropoxydiphenyl sulfone, bis (3-
Allyl-4-hydroxyphenyl) sulfone or 2,4 '
-The thermosensitive recording medium according to claim 2, which is dihydroxydiphenyl sulfone.