JPH11216957A - Thermal recording body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording body excellent in the resistance to heat and light. SOLUTION: In a thermal recording body wherein an undercoat layer, a thermal recording layer containing a colorless or light-colored dye precursor and a developer as main constituents and a protective layer are provided sequentially on a substrate, the developer includes a compound expressed by the formula, for instance, and an ultraviolet absorber is contained in the undercoat layer and/ or the thermal recording layer, an ultraviolet screener being contained in the thermal recording layer and/or the protective layer and a fluorescent dye being contained in the protective layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material using an aminobenzenesulfonamide derivative as a developer and having excellent heat resistance and light resistance.

[0002]

2. Description of the Related Art In general, a heat-sensitive recording sheet is usually prepared by grinding and dispersing a colorless or pale-colored dye precursor and a developer such as a phenolic compound into fine particles, and then mixing the two with a binder. Filler, sensitivity enhancer, a coating solution obtained by adding a lubricant and other auxiliaries, paper, synthetic paper, film, is applied to a support such as plastic,
A color is formed by an instantaneous chemical reaction caused by heating of a thermal head, a hot stamp, a hot pen, a laser beam or the like, and a recorded image is obtained.

[0003] These heat-sensitive recording materials include a measuring recorder, a computer terminal printer, a facsimile,
It has been applied to a wide range of fields, such as automatic ticket vending machines and bar code labels, but with the diversification and advancement of performance of these recording devices, the required quality of thermal recording sheets has become higher. I have. For example, with the increase in recording speed, it is required to obtain a high-density and vivid color image even with a small amount of thermal energy. On the other hand, excellent storage stability such as heat resistance, water resistance, oil resistance and plasticizer resistance is required. A thermal recording sheet is required.

[0004] In recent years, as systems for recording on plain paper such as the electrophotographic system and the ink jet system have become widespread, there have been more opportunities to compare thermal recording with those on plain paper. For example, the stability of the image is the same quality as toner recording,
It is required that the stability of the non-recording area (blank paper or ground color) before and after recording (hereinafter referred to as ground color stability) be close to the quality of plain paper recording. Due to the use of heat-sensitive recording paper as a food label to be performed and the use of heat laminating for use in cards such as lift tickets, there is an increasing demand for ground color stability against heat of 100 ° C. or more.

Accordingly, the present inventors have previously proposed a heat-sensitive recording medium having heat resistance even at a high temperature of 100 ° C. or higher as disclosed in
JP-A-304727, JP-A-8-25810, JP-A-8-53407, JP-A-8-59603, JP-A-8-132939, JP-A-8-290
671, JP-A-8-310134, JP-A-9-86049, and JP-A-8-58242.
JP-A-8-290672, JP-A-8-290672
No. 24127, an aminosulfonyl group (-
A thermal recording medium using an aminobenzenesulfonamide derivative having SO ₂ NH ₂ ) as a developer has been proposed.

When an aminobenzenesulfonamide derivative is used as a color developer, it has been confirmed that it has extremely high heat resistance even at a high temperature of 100 ° C. or more, and that the contrast between the ground color portion and the color-developed portion is high even when heat lamination is performed. Have been. Recently, however, these heat-sensitive recording media are required to have high light resistance that can maintain quality even when exposed to sunlight for a long time in outdoor use such as ski lift tickets and product tag paper. In the case of a heat-sensitive recording medium using a benzenesulfonamide derivative as a developer, there is a disadvantage that discoloration of the ground color or fading of an image portion occurs when exposed to sunlight.

[0007] On the other hand, various methods have hitherto been attempted for the purpose of improving light resistance. JP 63
Japanese Patent No. -307981 describes that an ultraviolet absorber is contained in a heat-sensitive recording layer. However, this method has a problem that heat resistance is poor because the melting point of the ultraviolet absorber is generally low. JP-A-61-193883 discloses that a benzotriazole-based hydrophobic ultraviolet absorber is contained in a protective layer. However, this method has a drawback that sticking and sticking occur during printing. The case where a water-soluble ultraviolet absorber is used is described in JP-A-7-17131. However, in this method, ions such as sodium salts are formed upon solubilization of the water-soluble ultraviolet absorber, so that there is a drawback that the thermal head is electrochemically worn. JP-A-62-176879 describes that a benzotriazole compound is contained in an undercoat layer and a protective layer for the purpose of absorbing also ultraviolet rays from the back surface. However, even with this method, the ultraviolet absorber in the protective layer causes sticking and sticking during printing, and a heat-sensitive recording material of sufficient quality could not be obtained.

Japanese Patent Application Laid-Open No. 62-18626 describes that a heat-sensitive recording layer contains zinc oxide which is an inorganic filler having an ultraviolet shielding effect. However, according to this method, in the case of an inorganic filler having an ultraviolet shielding effect, although the ultraviolet shielding effect is large, the transmittance in the visible light region is small, and the coloring portion is concealed and the printing density is lowered. Therefore, if the amount used is reduced to such an extent that a sufficient print density can be maintained, there is a problem that the effect of blocking ultraviolet rays is deteriorated and is not practical. JP-A-6-64324 discloses that a protective layer contains cerium oxide fine particles. However, in this method, cerium oxide itself may be colored, which is not suitable as a material for a thermal recording medium.

Further, Japanese Patent Application Laid-Open No. 7-25147 discloses that cerium oxide is coated on core particles made of an inorganic pigment,
It is described that a protective layer contains an ultraviolet ray blocking agent having a three-layer structure in which a cerium oxide-coated surface is coated with an inorganic pigment identical or different from the inorganic pigment. However, in this method, although the coloring of the cerium oxide is somewhat less noticeable,
The ultraviolet blocking effect of cerium oxide was blocked, and sufficient light resistance could not be obtained.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a heat-sensitive recording material which has heat resistance to a certain extent capable of being thermally laminated, and furthermore has light resistance in which a ground color portion and an image portion are stable to light. The challenge is to provide.

[0011]

The object of the present invention is to provide an undercoat layer, a heat-sensitive recording layer containing a colorless or pale-color dye precursor and a color developer as main components, and a protective layer on a support. In the heat-sensitive recording medium, the developer contains at least one compound represented by the following general formula (1), and contains an ultraviolet absorber in the undercoat layer and / or the heat-sensitive recording layer, This was achieved by including an ultraviolet ray blocking agent in the heat-sensitive recording layer and / or the protective layer and a fluorescent dye in the protective layer.

[0012]

Embedded image (Wherein, X represents an oxygen atom or a sulfur atom;
Represents an unsubstituted or substituted phenyl group, naphthyl group, aralkyl group, lower alkyl group having 1 to 6 carbon atoms, cycloalkyl group, or lower alkenyl group having 2 to 6 carbon atoms. Z represents a lower alkyl group having 1 to 6 carbon atoms or an electron-withdrawing group. n represents the integer of 0-4. )

Above all, the compound represented by the following general formula (2) is preferably used from the viewpoint of heat resistance effect, availability of synthesis raw materials, economy, reactivity (yield) and the like.

Embedded image (In the formula, Y represents a lower alkyl group having 1 to 6 carbon atoms or an electron-withdrawing group. M represents an integer of 0 to 3.)

A thermosensitive recording medium using the compound represented by the above general formula (1) or (2) as a developer can be recorded with a thermal head or the like.
Even in a thermal environment at about 20 ° C. to 140 ° C., it exhibits the characteristic that the ground color is less developed.

The aminobenzenesulfonamide derivative represented by the general formula (1) or (2) used in the present invention undergoes a structural change from the neutral structure represented by the above general formula (keto-type structure in the case of urea) upon heating. It is considered that the color developing ability is exhibited by causing a change to an acidic structure (enol type structure in the case of urea). In order to stabilize this acidic structure, an aminosulfonyl group (—SO ₂ NH ₂ ) is placed at the N-position (or 1-position) of the urea structure or thiourea structure of the general formula (1) or (2) of the present invention. It is sufficient that an aromatic ring having the formula (1) and an electron-withdrawing sulfonyl group are present.

Accordingly, R in the general formula (1) is not particularly limited as long as it does not impair the color developing ability and stability. And lower alkyl groups, cycloalkyl groups and lower alkenyl groups having 2-6 carbon atoms. Further, R in the general formula (1) may contain a substituent that does not impair the color development and heat resistance. Examples of the substituent include a lower alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group, a lower alkenyl group such as an isopropenyl group, and an electron-withdrawing group such as fluorine, chlorine, bromine, and a nitro group. . Further, Z in the general formula (1) may be any substituent that does not impair color development and heat resistance. Examples of such a substituent include a lower alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group, or fluorine, chlorine, bromine,
Examples thereof include an electron-withdrawing group such as a nitro group.

With respect to the aminobenzenesulfonamide derivative represented by the general formula (1) or (2) of the present invention,
As disclosed in detail in the above-mentioned JP-A-8-58242 and the like by the present inventors, for example, as a synthesis method, aminobenzenesulfonamides and isocyanates or isothiocyanates are used. It can be produced by a reaction. That is, in the reaction, the isocyanate ester or the isothiocyanate ester is added at a ratio of 1 to 2.5 mol per 1 mol of the aminobenzenesulfonamide. As a solvent to be used, any solvent may be used as long as it dissolves aminobenzenesulfonamides, isocyanates, or isothiocyanates, for example, benzene, toluene, aromatic hydrocarbons such as xylene, chloroform,
Dichloromethane, halogenated aromatic hydrocarbons such as chlorobenzene, diethyl ether, ethers such as tetrahydrofuran, acetonitrile, nitriles such as propionitrile, esters such as ethyl acetate, acetone, ketones such as methyl ethyl ketone, dimethylformamide, Non-proton donating polar solvents such as dimethyl sulfoxide; alcohols such as methanol and ethanol; and mixed solvents thereof. The reaction temperature ranges from 0 to 150C, preferably from 20 to 100C.

The reason why the heat-sensitive recording material using this material exhibits high heat resistance is that, since it functions as a color developer, the structure changes from a neutral type to an acidic type under a high temperature condition as shown in the following formula ( In the case where X is an oxygen atom, it is considered to be due to keto-enol tautomerism).

[0019]

Embedded image (In the formula, X represents an oxygen atom or a sulfur atom.)

In the case of a thermosensitive recording medium, the temperature of the thermal head for supplying heat instantaneously rises to 200 to 300 ° C. or higher, so that the compound represented by the general formula (1) or (2) causes tautomerism. Sufficient thermal conditions for developing the color developing function are provided. As a result, the lactone ring of the dye precursor is cleaved to form a color. Furthermore, the aminosulfonyl group is considered to contribute to the promotion of the color developing function and the stabilization of the acidic structure, and therefore, it is presumed that a strong recorded image density and thermal stability of the image and the ground color can be obtained. You.

The temperature at which the above-mentioned tautomerization occurs is considered to be higher than the temperature required for thermal lamination. Therefore, even in a high-temperature thermal environment such as a thermal lamination process, the development of the ground color does not occur. Similarly, even when the toner comes into contact with the heat fixing portion of the toner of the electrophotographic copying machine, the coloring does not occur on the ground. Thermal recording can be performed before or after toner recording by the electrophotographic copying machine.

On the other hand, for the purpose of imparting light resistance, a commonly used general ultraviolet absorber is added to a thermosensitive recording medium using these aminobenzenesulfonamide derivatives as a color developer until the light resistance is satisfied. As shown in the results of Comparative Example 10 to be described later, the high heat resistance of the compound represented by the general formula (1) or (2) is impaired. Can not be obtained. Although the reason for this is not clearly understood, it is considered that the ultraviolet absorber exerts some chemical action on the aminobenzenesulfonamide derivative, so that color formation is likely to occur even at a relatively low temperature. In addition, since the melting point of the ultraviolet absorber is generally 140 ° C. or less, it is considered that one of the causes is that the ultraviolet absorber melts at a relatively low temperature and provides an environment where the developer and the dye precursor are easily brought into contact with each other. .

Further, since the heat-sensitive recording material using the aminobenzenesulfonamide derivative has high heat resistance, it is immersed in hot water for several minutes, for example, for sterilization treatment, or in a heat environment of about 60 to 130 ° C., such as a car dashboard in summer. It has the advantage that no ground color develops even when left underneath, but when an ultraviolet absorber is added to the heat-sensitive recording layer or the protective layer in order to improve the light resistance, Comparative Examples 6 to 9 and Comparative Example 25 to be described later.
As shown in the results of Nos. To 27, a phenomenon occurs that an image fades during storage in a high-temperature environment. This is probably because the UV absorber exerts some chemical action on the aminobenzenesulfonamide derivative at a high temperature to dissociate the dye-aminobenzenesulfonamide derivative complex which is in a colored state.

The inventors of the present invention have conducted intensive studies with the aim of improving light resistance while maintaining high heat resistance, and as a result, have been shown that, together with the compound represented by the general formula (1) or (2), ultraviolet absorption It has been found that the above object can be achieved by using an agent, an ultraviolet ray blocking agent, and a fluorescent dye, and the present invention has been completed. Further, in the present invention, the blending number of the ultraviolet absorber, the ultraviolet ray blocking agent, and the fluorescent dye is used in a specific range, and when the ultraviolet absorber is contained in the heat-sensitive recording layer, the melting point is set to a specific temperature or higher. Thereby, a better effect can be obtained. In the present invention, it is not clear why the heat-resistant image storage stability of the aminobenzenesulfonamide derivative under a high-temperature environment is not impaired. It is presumed that the adverse effects of the absorbent may be suppressed.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to obtain a thermosensitive recording medium of the present invention,
For example, first, an undercoat layer coating solution is prepared by dispersing an ultraviolet absorber composed of a benzotriazole compound together with a binder and a filler, and then coated on a support and dried to form an undercoat layer.
Next, a dispersion in which the dye and the developer are respectively dispersed together with a binder is mixed, and a refractive index of 1.5 to
Sintering of specific particles having a three-layer structure in which the surface of the flaky pigment of 1.6 is coated with an insoluble cerium compound and amorphous silica, or firing of particles having a two-layer structure in which the insoluble cerium compound is coated with amorphous silica A heat-sensitive recording layer coating solution is prepared by adding a UV blocking agent, a UV absorber dispersion liquid, a filler, and other necessary additives such as materials, and then coating and drying on the undercoat layer to form a heat-sensitive recording layer. In addition, fluorescent dyes,
If necessary, a baked product of specific particles having a three-layer structure in which the surface of a flake pigment having a refractive index of 1.5 to 1.6 is coated with an insoluble cerium compound and amorphous silica, or an insoluble cerium compound is coated with amorphous silica. A protective layer coating solution containing an ultraviolet ray blocking agent such as a fired product of coated particles having a two-layer structure, a water-soluble polymer and an additive such as a filler is prepared, and the protective layer is coated and dried on the heat-sensitive recording layer. The thermosensitive recording medium of the present invention can be manufactured by forming

In the heat-sensitive recording material of the present invention, various known hydrophobic or water-soluble ones can be used as the ultraviolet absorber contained in the undercoat layer or the heat-sensitive coloring layer.
Examples of the hydrophobic ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, and 2,2 ′. -Dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4 '
Benzophenone ultraviolet absorbers such as -dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2- (2'-hydroxyphenyl)
Benzotriazole, 2- (2'-hydroxy-5'-
Methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-te
rt-butylphenyl) benzotriazole, 2- (2 ′
-Hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-
Hydroxy-3 ′, 5′-di-tert-butylphenyl)
-5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-aminophenyl) benzotriazole, 2- (2'-hydroxy-3', 5'-
Di-tert-butylphenyl) -5-tert-butylbenzotriazole, 2- (2'-hydroxy-3'-dodecyl-5'-methylphenyl) benzotriazole, 2-
[2′-hydroxy-4 ′-(2 ″ -ethylhexyl) oxyphenyl] benzotriazole, methyl-3
Condensation product with-[3-tert-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate-polyethylene glycol (molecular weight: about 300), 5-tert-butyl-3- (5-chloro-2H-
Benzotriazol-2-yl) -4-hydroxybenzene-octyl propionate, 2,2-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6
-(2H-benzotriazol-2-yl) phenol], 2- (2'-hydroxy-3'-sec-butyl-
Benzotriazole UV absorbers such as 5'-tert-butylphenyl) -5-tert-butylbenzotriazole, and salicylic acid UV absorbers such as phenyl salicylate, p-tert-butylphenyl salicylate and p-octylphenyl salicylate Agent, 2-ethylhexyl-2
A cyanoacrylate-based ultraviolet absorber such as -cyano-3,3'-diphenylacrylate, ethyl-2-cyano-3,3'-diphenylacrylate;
6,6, -tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, 2- (3,5-di-tert-ester)
Hindered amine-based ultraviolet absorbers such as -butyl) malonic acid-bis (1,2,2,6,6-pentamethyl-4-piperidyl) ester and the like.

As the water-soluble ultraviolet absorber, for example, 2
-Hydroxy-4-methoxybenzophenone-5-sulfonic acid, sodium 2-hydroxy-4-methoxybenzophenone-5-sulfonate, potassium 2-hydroxy-4-methoxybenzophenone-5-sulfonate, 2,
Sodium 2'-dihydroxy-4,4'-dimethoxybenzophenone-5-sulfonate, sodium 2,4-dihydroxybenzophenone-5-sulfonate,
Sodium 2'-dihydroxy-4,4'-dimethoxybenzophenone-5,5'-disulfonate, sodium 2,4-dihydroxybenzophenone-5'-sulfonate, 2,2 ', 4,4'-tetrahydroxybenzophenone- Benzophenone-based ultraviolet absorbers such as sodium 5,5'-disulfonate, 2- (2'-hydroxy-
4'-methoxy-5'-sulfophenyl) benzotriazole sodium salt, 2- (2'-hydroxy-4'-
Butoxy-5'-sulfophenyl) benzotriazole sodium salt and other benzotriazole ultraviolet absorbers.

The present invention is not limited to these, but among them, a benzotriazole-based ultraviolet absorber having the highest effect on light resistance is preferably used. Also, two or more kinds can be used in combination as needed. In particular, when it is contained in the heat-sensitive recording layer, it has a high light resistance and a high melting point.
Methylene bis [4- (1,1,3,3, -tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] is desirable because it causes less coloring and improves the heat resistance of the thermosensitive recording medium.

The UV absorber is used in an amount of 0.1% by weight to 15% by weight based on the dry weight of the undercoat layer, and 0.1% by weight to 8% by weight based on the dry weight of the thermosensitive coloring layer. Let it. More preferably, it is in the range of 1% by weight to 10% by weight based on the dry weight of the undercoat layer, and 2% by weight to 6% by weight based on the dry weight of the heat-sensitive recording layer. When the amount of the UV absorber used in the undercoat layer or the heat-sensitive recording layer is 0.1% by weight or less, the effect on light resistance is low, and 15% by weight or more of the undercoat layer or 8% by weight or more of the heat-sensitive recording layer. In this case, the heat resistance, color development sensitivity and image storability of the thermosensitive recording medium are reduced.

In the heat-sensitive recording medium of the present invention, it is desirable that the ultraviolet ray blocking agent contained in the heat-sensitive recording layer or the protective layer has high transparency and low hiding property from the viewpoint of color sensitivity.
Examples of such an ultraviolet blocking agent include a flaky pigment having a refractive index of 1.5 to 1.6 according to claim 3 of the present invention, which is coated with an insoluble cerium compound and further coated with amorphous silica. A fired product of particles having a layered structure or a fired product of particles having a two-layered structure in which the insoluble cerium compound according to claim 4 of the present invention is coated with amorphous silica can be given. In the present invention, these are preferably used. Used.

For such an ultraviolet ray blocking agent, a fired product of particles having a three-layer structure is disclosed in JP-A-6-145645 and is well known. A fired product of particles having a two-layer structure is described in JP-A-9-202048 and is well known. In order to produce this ultraviolet blocking agent having a three-layer structure, first, an aqueous cerium salt solution is added dropwise to an aqueous dispersion of a flake pigment under heating as 1-30% by weight as CeO2 with respect to the pigment, and the pH is adjusted to 7-9. Then, an insoluble cerium compound is deposited on the pigment surface to obtain a cerium-coated pigment. Next, a silicate solution is added to the aqueous dispersion of the cerium-coated pigment under heating to adjust the pH to 6 to 8, and the amorphous silica is deposited and coated on the surface of the pigment, and then calcined at a high temperature of 200 ° C. or more. It is obtained by doing. The amount of amorphous silica deposited is 2
-40% by weight.

The pigment serving as the nucleus is preferably in the form of a flake and has a refractive index of about 1.5 to 1.6. Such pigments include mica, talc, sericite, aluminum hydroxide, calcium carbonate, kaolin, calcium hydroxide, aluminum silicate, polyethylene powder,
Examples include polystyrene and latex. Among them, mica, talc, and sericite are preferable because a thermosensitive recording medium having a good color density can be obtained. Further, as the cerium compound, cerium chloride, cerium nitrate, cerium sulfate and the like can be used, and as the silicate,
Organic silicates can be used in addition to inorganic salts such as sodium silicate.

The baked product of the particles having a two-layer structure is prepared by adding a cerium hydroxide slurry produced by adding a cerium salt solution and an alkaline solution to water maintained at a liquid temperature of 60 ° C. or lower and a pH of 5 or higher. It is manufactured by a method in which a non-crystalline silica is formed by adding a sodium silicate solution and a mineral acid solution while heating to not less than 9 ° C. and keeping the pH at not less than 9, washing with water, filtering, and then drying or calcining.

The amount of the ultraviolet ray blocking agent used is from 10% by weight to 40% by weight based on the dry weight of the heat-sensitive recording layer.
It is preferred to contain. When the content is 10% by weight or less, the effect on light resistance is small, and when the content is 40% by weight or more, the coloring sensitivity is reduced. In the protective layer, the content is preferably 5% by weight to 40% by weight based on the dry weight. 5
When the content is less than 40% by weight, the effect on light resistance is small, and
When the content is more than 10% by weight, the barrier properties of the protective layer and the color sensitivity are reduced.

As the fluorescent dye, various known dyes can be used, and examples thereof include stilbene derivatives, coumarin derivatives, pyrazoline derivatives, bisstyrylbiphenyl derivatives, naphthalimide derivatives, bisbenzooxazolyl derivatives, and the like. However, diaminostilbene disulfone derivatives are particularly preferred because of their high effect on light resistance.

The amount of the fluorescent dye used is preferably 0.01 to 3% by weight based on the dry weight of the protective layer. More preferably, it is in the range of 0.1 to 2% by weight.
When the amount of the fluorescent dye in the protective layer is 0.01% by weight or less, the effect on light resistance is reduced, and when the amount is 3% by weight or more, coloring of the protective layer paint becomes intense, and the ground color of the recording medium is reduced. Connect.

The ultraviolet ray blocking agent preferably used in the present invention has a characteristic layer structure and can maintain a sufficient whiteness. In addition, since it is composed of a pigment generally used in a heat-sensitive recording medium, even if it is contained in the heat-sensitive recording layer, no adverse effects such as background fog and desensitization are observed. Further, the ultraviolet ray blocking agent may be contained in the undercoat layer.

However, the light resistance required by the present invention cannot be obtained even when the heat-sensitive recording medium contains only the ultraviolet ray blocking agent. This is probably because the cerium compound is covered with amorphous silica, and the ultraviolet blocking effect of the cerium compound is blocked. In particular, when the undercoat layer contains an ultraviolet absorber, the thermosensitive coloring layer contains an ultraviolet absorber or an ultraviolet ray blocking agent, and the protective layer further contains a fluorescent dye, a high light resistance is obtained. It is a target. When the heat-sensitive recording layer contains an ultraviolet absorber and an ultraviolet blocker, it is preferable to mix the ultraviolet absorber and the ultraviolet shield in a ratio of 1: 4 to 4: 1.

Further, in the present invention, an ultraviolet absorber is contained in the undercoat layer or the thermosensitive coloring layer,
It is considered that not only the ultraviolet ray from the rear surface of the thermosensitive recording medium is absorbed, but also the ultraviolet absorbing ability is increased due to a synergistic effect with the ultraviolet ray blocking agent in the thermosensitive recording layer.

As the binder in the undercoat layer of the present invention, a commonly used emulsion of a water-soluble polymer or a hydrophobic polymer can be appropriately used.
Specific examples include cellulose derivatives such as polyvinyl alcohol, polyvinyl acetal, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, starch and its derivatives, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylate copolymer, and acrylamide. Water-soluble polymers such as / acrylic acid ester / methacrylic acid copolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, etc. Vinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / bi-acetate Alcohol copolymer can be used styrene / butadiene / emulsion of a hydrophobic polymer such as an acrylic copolymer.

As the filler in the undercoat layer, known fillers conventionally used generally, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, magnesium hydroxide, calcined kaolin, In addition to inorganic fillers such as clay and talc, organic fillers such as styrene-methacrylic copolymer resin, urea-formalin resin, and polystyrene resin can be used.

In the protective layer of the present invention, various known fillers can be used. Specific examples of such fillers include kaolin, clay, calcium carbonate, calcined clay,
Inorganic pigments such as calcined kaolin, aluminum hydroxide, titanium oxide, diatomaceous earth, fine anhydrous silica, activated clay, and organic pigments such as styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, raw starch particles, and the like. Can be

As the binder in the protective layer, a binder composed of a polymer compound usually used in the field of thermal recording can be used. Specific examples of such a binder include, for example, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, polyvinyl acetate , Vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, acrylonitrile-butadiene-styrene copolymer, vinyl acetate-acrylic acid copolymer, ethylene-acrylic acid copolymer, styrene-acrylic acid copolymer Copolymer, acrylic ester resin, acrylic emulsion, diisobutylene / maleic anhydride copolymer, styrene / maleic anhydride copolymer, styrene / butadiene copolymer emulsion , Methyl methacrylate-butadiene copolymer, methyl methacrylate-styrene-butadiene copolymer, styrene polymer, isoprene polymer, butadiene polymer, vinyl chloride polymer, vinylidene chloride polymer, urea resin, melamine resin, amide Resin, polyurethane resin and the like can be exemplified.

Further, in the protective layer, if necessary, a lubricant such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax and the like, and a surfactant such as sodium dioctyl sulfosuccinate (dispersant, wetting agent) Agents), an antifoaming agent, and various auxiliaries such as water-soluble polyvalent metal salts such as potassium alum and aluminum acetate. Further, in order to further improve the water resistance, a curing agent such as glyoxal, boric acid, dialdehyde starch, or an epoxy compound can be used in combination.

As the dye precursor to be used in the heat-sensitive recording material of the present invention, any of those known in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used and is not particularly limited. Compounds, fluorane compounds, fluorene compounds, divinyl compounds and the like are preferred. Specific examples of typical dye precursors are shown below. These dye precursors may be used alone or in combination of two or more.

<Triphenylmethane leuco dye> 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide [also known as crystal violet lactone] 3,3-bis (p-dimethylaminophenyl) phthalide Malachite green lactone] <Fluoran leuco dye> 3-Diethylamino-6-methylfluoran 3-Diethylamino-6-methyl-7-anilinofluoran 3-Diethylamino-6-methyl-7- (o, p-dimethyl Anilino) fluoran 3-diethylamino-6-methyl-7-chlorofluoran 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-6-methyl-7- (o- Chloroanilino) fluoran 3-diethylamino-6-methyl Le-7- (p-chloroanilino) fluoran 3-diethylamino-6-methyl-7- (o-fluoroanilino) fluoran 3-diethylamino-6-methyl-7-n-octylanilinofluoran 3-diethylamino-6 -Methyl-7-n-octylaminofluoran 3-diethylamino-6-methyl-7-benzylanilinofluoran 3-diethylamino-6-methyl-7-dibenzylanilinofluoran 3-diethylamino-6-chloro- 7-methylfluoran 3-diethylamino-6-chloro-7-anilinofluoran 3-diethylamino-6-chloro-7-p-methylanilinofluoran 3-diethylamino-6-ethoxyethyl-7-anilinofur Oran 3-diethylamino-7-methylfluoran 3-diethylamino- -Chlorofluoran 3-diethylamino-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-7- (o-chloroanilino) fluoran 3-diethylamino-7- (p-chloroanilino) fluoran 3-diethylamino-7- (O-fluoroanilino) fluoran 3-diethylamino-benzo [a] fluoran 3-diethylamino-benzo [c] fluoran 3-dibutylamino-6-methyl-fluoran 3-dibutylamino-6-methyl-7-anilinofur Oran 3-Dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluoran 3-Dibutylamino-6-methyl-7- (o-chloroanilino) fluoran 3-Dibutylamino-6-methyl-7- (P-chloroanilino) fluoran 3-dibutyl Amino-6-methyl-7- (o-fluoroanilino) fluoran 3-dibutylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-dibutylamino-6-methyl-chlorofluoran 3 -Dibutylamino-6-ethoxyethyl-7-anilinofluoran 3-dibutylamino-6-chloro-7-anilinofluoran 3-dibutylamino-6-methyl-7-p-methylanilinofluoran 3- Dibutylamino-7- (o-chloroanilino) fluoran 3-dibutylamino-7- (o-fluoroanilino) fluoran 3-n-dipentylamino-6-methyl-7-anilinofluoran 3-n-dipentylamino- 6-methyl-7- (p-chloroanilino) fluoran 3-n-dipentylamino-6-chloro-7-ani Linofluoran 3-n-dipentylamino-7- (p-chloroanilino) fluoran 3-pyrrolidino-6-methyl-7-anilinofluoran 3-piperidino-6-methyl-7-anilinofluoran 3- (N-methyl -N-propylamino) -6-methyl-7-anilinofluoran 3- (N-methyl-N-cyclohexylamino) -6
Methyl-7-anilinofluoran 3- (N-ethyl-N-cyclohexylamino) -6
Methyl-7-anilinofluoran 3- (N-ethyl-N-xylamino) -6-methyl-
7- (p-chloroanilino) fluoran 3- (N-ethyl-p-toluidino) -6-methyl-
7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-chloro-7-anilino Fluoran 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran 3- (N-ethyl-N-isobutylamino) -6-methyl-7-anilinofluoran 3-cyclohexylamino-6-chlorofluoran 2- (4-oxahexyl) -3-dimethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-diethylamino-6
-Methyl-7-anilinofluoran 2- (4-oxahexyl) -3-dipropylamino-
6-methyl-7-anilinofluoran 2-methyl-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluoran 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2 -Chloro-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-nitro-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-amino-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2- Benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2-hydroxy-6-p- (p-phenylaminophenyl) aminoanilinofluoran 3-methyl-6-p- (p-dimethyl Aminophenyl)
Aminoanilinofluoran 3-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluoran <Fluorene leuco dye>3,6,6'-Tris (dimethylamino) spiro [fluorene-9,3'-phthalide] 3,6,6'-Tris (diethylamino) spiro [fluorene-9,3'-phthalide] <Divinyl leuco dye > 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5
6,7-tetrabromophthalide 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5
6,7-tetrachlorophthalide 3,3-bis- [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide 3,3- Bis- [1- (4-methoxyphenyl) -1-
(4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrachlorophthalide <Others> 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-ethyl-2-methylindol-3-yl)
-4-azaphthalide 3- (4-diethylamino-2-ethoxyphenyl)-
3- (1-octyl-2-methylindol-3-yl) -4-azaphthalide 3- (4-cyclohexylethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) ) -4-Azaphthalide 3,3-bis (1-ethyl-2-methylindole-3
-Yl) phthalide 3,6-bis (diethylamino) fluoran-γ- (3
'-Nitro) anilinolactam 3,6-bis (diethylamino) fluoran-γ- (4
'-Nitro) anilinolactam 1,1-bis- [2', 2 ', 2 ", 2" -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,
2-dinitrileethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2-
β-naphthoylethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,
2-Diacetylethane bis- [2,2,2 ', 2'-tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester

In the heat-sensitive recording medium of the present invention, the compound represented by formula (1) or (2) used as a color developer in the heat-sensitive coloring layer is specifically exemplified by the following (A-1). ~ (A-54) or (B-1) ~
(B-18), but not limited thereto. Particularly, the compounds represented by the general formula (2) include (A-1) to (A-8) and (A-10) to (A-1).
7), (A-19) to (A-25), or (A-2)
7) applies.

[0048]

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[0049]

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[0050]

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[0051]

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[0052]

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[0053]

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[0054]

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[0055]

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In the present invention, one or two or more types of conventionally known color developing agents which form a dye precursor are used as long as the desired effects on the above-mentioned objects are not inhibited. It can be used in combination with the compound represented by (2). When producing a thermosensitive recording medium having extremely excellent heat resistance, it is better to avoid using a conventionally known color developer, but depending on the heat resistance temperature characteristics for the intended thermal environment, a conventionally known color developer may be used. Can be added in an appropriate amount and used in combination. Examples of such a developer include, for example, JP-A-3-207688.
, 4-hydroxybenzoic acid esters, 4-hydroxyphthalic acid diesters, phthalic acid monoesters, bis- (hydroxyphenyl) sulfides,
Hydroxyphenylarylsulfones, 4-hydroxyphenylarylsulfonates, 1,3-di [2-
(Hydroxyphenyl) -2-propyl] -benzenes, 4-hydroxybenzoyloxybenzoic acid esters, and bisphenolsulfones. Specific examples of typical known color developers are shown below, but the present invention is not particularly limited thereto.

<Bisphenol A>4,4'-isopropylidene diphenol (also called bisphenol A) 4,4'-cyclohexylidene diphenol p, p '-(1-methyl-normalhexylidene) diphenol 1, 7-di (hydroxyphenylthio) -3,5-dioxaheptane <4-hydroxybenzoates> Benzyl 4-hydroxybenzoate Ethyl 4-hydroxybenzoate Propyl 4-hydroxybenzoate 4-Isopropyl benzoate 4 -Butyl hydroxybenzoate 4-Isobutyl 4-hydroxybenzoate Methylbenzyl 4-hydroxybenzoate <Dimethyl 4-hydroxyphthalates> Dimethyl 4-hydroxyphthalate 4-Diisopropyl 4-hydroxyphthalate 4-Dibenzyl 4-hydroxyphthalate 4-hydro Dihexyl phthalate <monoesters of phthalic acid> monobenzyl phthalate monocyclohexyl phthalate monophenyl phthalate monomethyl phenyl phthalate monoethyl phenyl phthalate monopropyl benzyl phthalate monohalogen benzyl phthalate phthalic acid Monoethoxybenzyl ester <Bis- (hydroxyphenyl) sulfides> Bis- (4-hydroxy-3-tert-butyl-6-
Methylphenyl) sulfide bis- (4-hydroxy-2,5-dimethylphenyl)
Sulfide bis- (4-hydroxy-2-methyl-5-ethylphenyl) sulfide bis- (4-hydroxy-2-methyl-5-isopropylphenyl) sulfide bis- (4-hydroxy-2,3-dimethylphenyl)
Sulfide bis- (4-hydroxy-2,5-dimethylphenyl)
Sulfide bis- (4-hydroxy-2,5-diisopropylphenyl) sulfide bis- (4-hydroxy-2,3,6-trimethylphenyl) sulfide bis- (2,4,5-trihydroxyphenyl) sulfide bis- ( 4-hydroxy-2-cyclohexyl-5-methylphenyl) sulfide bis- (2,3,4-trihydroxyphenyl) sulfide bis- (4,5-dihydroxy-2-tert-butylphenyl) sulfide bis- (4- Hydroxy-2,5-diphenylphenyl) sulfide bis- (4-hydroxy-2-tert-octyl-5)
-Methylphenyl) sulfide <4-hydroxyphenylarylsulfones>4-hydroxy-4'-isopropoxydiphenylsulfone4-hydroxy-4'-propoxydiphenylsulfone4-hydroxy-4'-n-butyloxydiphenylsulfone 4- Hydroxy-4'-n-propoxydiphenylsulfone <4-hydroxyphenylarylsulfonates> 4-hydroxyphenylbenzenesulfonate 4-hydroxyphenyl-p-tolylsulfonate 4-hydroxyphenylmethylenesulfonate 4-hydroxyphenyl-p -Chlorobenzenesulfonate 4-hydroxyphenyl-p-tert-butylbenzenesulfonate 4-hydroxyphenyl-p-isopropoxybenzenesulfonate 4-hydroxy Phenyl-1'-naphthalenesulfonate 4-hydroxyphenyl-2'-naphthalenesulfonate <1,3-di [2- (hydroxyphenyl) -2-propyl] benzenes> 1,3-di [2- (4 -Hydroxyphenyl) -2-propyl] benzene 1,3-di [2- (4-hydroxy-3-alkylphenyl) -2-propyl] benzene 1,3-di [2- (2,4-dihydroxyphenyl) −
2-propyl] benzene 1,3-di [2- (2-hydroxy-5-methylphenyl) -2-propyl] benzene <resorcinols> 1,3-dihydroxy-6 (α, α-dimethylbenzyl) -benzene <4-Hydroxybenzoyloxybenzoate> Benzyl 4-hydroxybenzoyloxybenzoate Methyl 4-hydroxybenzoyloxybenzoate Ethyl 4-hydroxybenzoyloxybenzoate Propyl 4-hydroxybenzoyloxybenzoate Butyl 4-hydroxybenzoyloxybenzoate Isopropyl 4-hydroxybenzoyloxybenzoate tert-butyl 4-hydroxybenzoyloxybenzoate hexyl 4-hydroxybenzoyloxybenzoate octyl 4-hydroxybenzoyloxybenzoate 4-h Nonyl roxybenzoyloxybenzoate Cyclohexyl 4-hydroxybenzoyloxybenzoate β-phenethyl 4-hydroxybenzoyloxybenzoate Phenyl 4-hydroxybenzoyloxybenzoate α-Naphthyl 4-hydroxybenzoyloxybenzoate β-Hydroxybenzoyloxybenzoate β -Naphthyl sec-butyl 4-hydroxybenzoyloxybenzoate <Bisphenolsulfones (I)> bis- (3-1-butyl-4-hydroxy-6-methylphenyl) sulfone bis- (3-ethyl-4-hydroxyphenyl) ) Sulfone bis- (3-propyl-4-hydroxyphenyl) sulfone bis- (3-methyl-4-hydroxyphenyl) sulfone bis- (2-isopropyl-4-hydroxyphenyl)
Sulfone bis- (2-ethyl-4-hydroxyphenyl) sulfone bis- (3-chloro-4-hydroxyphenyl) sulfone bis- (2,3-dimethyl-4-hydroxyphenyl)
Sulfone bis- (2,5-dimethyl-4-hydroxyphenyl)
Sulfone bis- (3-methoxy-4-hydroxyphenyl) sulfone 4-hydroxyphenyl-2'-ethyl-4'-hydroxyphenylsulfone 4-hydroxyphenyl-2'-isopropyl-4'-
Hydroxyphenylsulfone 4-hydroxyphenyl-3'-isopropyl-4'-
Hydroxyphenylsulfone 4-hydroxyphenyl-3'-secbutyl-4'-
Hydroxyphenylsulfone 3-chloro-4-hydroxyphenyl-3'-isopropyl-4'-hydroxyphenylsulfone 2-hydroxy-5-t-butylphenyl-4'-hydroxyphenylsulfone 2-hydroxy-5-t-aminophenyl -4'-hydroxyphenylsulfone 2-hydroxy-5-t-isopropylphenyl-4 '
-Hydroxyphenylsulfone 2-hydroxy-5-t-octylphenyl-4'-hydroxyphenylsulfone 2-hydroxy-5-t-butylphenyl-3'-chloro-4'-hydroxyphenylsulfone 2-hydroxy-5-t -Butylphenyl-3'-methyl-4'-hydroxyphenylsulfone 2-hydroxy-5-tert-butylphenyl-3'-isopropyl-4'-hydroxyphenylsulfone 2-hydroxy-5-tert-butylphenyl-2 '-Methyl-4'-hydroxyphenylsulfone<Bisphenolsulfones(II)>4,4'-Sulfonyldiphenol2,4'-Sulfonyldiphenol3,3'-Dichloro-4,4'-sulfonyldiphenol 3, 3'-dibromo-4,4'-sulfonyldiphenol 3,3 ', 5,5'-Tetrabromo-4,4'-sulfonyldiphenol 3,3'-diamino-4,4'-sulfonyldiphenol <Others> p-tert-butylphenol 2,4-dihydroxybenzophenone novolak-type phenol resin 4-hydroxyacetophenone p-phenylphenol benzyl-4-hydroxyphenylacetate p-benzylphenol

In the present invention, conventionally known sensitizers can be used as long as the desired effects on the above objects are not impaired. When manufacturing a heat-sensitive recording material having extremely excellent heat resistance, it is generally better not to use a sensitizer, but it is necessary to add an appropriate amount of the sensitizer according to the heat-resistant temperature characteristics of the target thermal environment. Can be. Examples of such a sensitizer include fatty acid amides such as stearic acid amide and palmitic acid amide, ethylene bisamide, montanic acid wax, polyethylene wax, 1,2-di- (3-methylphenoxy) ethane, p-benzylbiphenyl, β- Benzyloxynaphthalene, 4-biphenyl-p-tolyl ether, m-terphenyl, 1,2-diphenoxyethane, dibenzyl oxalate, di (p-chlorobenzyl) oxalate, di (p-methylbenzyl) oxalate, Dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 1,4-diethoxynaphthalene, 1
-Hydroxy-2-naphthoic acid phenyl ester, o-
Xylerin-bis- (phenyl ether), 4- (m-
Examples thereof include, but are not particularly limited to, methylphenoxymethyl) biphenyl. These sensitizers may be used alone or in combination of two or more.

As the binder used in the heat-sensitive recording layer of the present invention, completely saponified polyvinyl alcohol having a degree of polymerization of 200 to 1900, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol Alcohol, modified polyvinyl alcohol such as butyral modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, cellulose derivatives such as acetyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride, poly (vinyl chloride) Vinyl acetate, polyacrylamide, polyacrylate,
Examples thereof include polyvinyl butyral, polystyrene and copolymers thereof, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, and cumarone resin. These high-molecular substances can be used by dissolving them in solvents such as water, alcohols, ketones, esters, and hydrocarbons.Also, they can be used in emulsified or paste-like form in water or other media. You can also.

Also, in the present invention, metal salts of p-nitrobenzoic acid (Ca, Zn), which are known stabilizers exhibiting an oil resistance effect of a recorded image and the like, as long as the desired effects on the above-mentioned problems are not impaired, Alternatively, phthalic acid monobenzyl ester metal salt (Ca, Zn) can be added.

The fillers that can be used in the heat-sensitive recording layer of the present invention include silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide,
Examples include inorganic or organic fillers such as zinc oxide, aluminum hydroxide, polystyrene resin, urea-formalin resin, styrene-methacrylic acid copolymer, styrene-butadiene copolymer, and hollow plastic pigment.

In addition, release agents such as fatty acid metal salts, lubricants such as waxes, water-resistant agents such as glyoxal,
Dispersants, defoamers, antioxidants, fluorescent dyes and the like can be used.

The amounts of the developer and the dye precursor used in the heat-sensitive recording layer of the present invention and the types and amounts of other various components are determined according to the required performance and recording suitability, and are not particularly limited. Usually, with respect to 1 part of the dye precursor,
The developer of 1 to 8 parts of the present invention and the filler of 1 to 20 parts are used, and the binder is suitably used at 10 to 25% of the total solid content. When the heat-sensitive recording layer contains an ultraviolet absorber and an ultraviolet ray blocking agent, the ratio between the ultraviolet ray absorbing agent and the ultraviolet ray blocking agent is 1: 4 to
It is good to mix at a ratio of 4: 1.

The above-described developer, dye precursor, and optionally added materials are pulverized by a pulverizer such as a ball mill, an attritor, a sand grinder or an appropriate emulsifying device to a particle size of several microns or less. A coating liquid is prepared by adding a binder and various additives depending on the purpose.

As the support, paper, synthetic paper, plastic film, non-woven fabric, metal foil and the like can be used, or a composite sheet combining these can be used. The desired thermosensitive recording medium can be obtained by sequentially applying a coating solution for each layer having the above composition to any one of these supports.

[0066] The coating amount of the undercoat layer coating liquid for 2~12g / m ² by dry weight, 2 to preferably 3 to 10 g / m ² approximately, the coating amount of the heat-sensitive recording layer coating composition in a dry weight 12g /
m ^2, is preferably adjusted 3 to 10 g / m ² approximately, the coating amount of the protective layer coating composition is 0.1 to 20 g / m ² by dry weight, preferably 0.5 to 10 g / m ² range of about You.

[0067]

EXAMPLES <Production example 1 of ultraviolet blocking agent> Flake-like pigment 500 serving as a core material of the ultraviolet blocking agent used in the present invention
g was dispersed in 10 liters of water, and 264 g of an aqueous cerium nitrate solution was added dropwise while heating and stirring at 80 ° C. Subsequently, the solution was neutralized to pH 7 to 9 with a sodium hydroxide solution, cerium hydroxide was deposited on the surface of the pigment, and then dried and pulverized to obtain a cerium-coated pigment. Next, after dispersing the cerium-coated pigment in 10 liters of water, 348 g of No. 3 sodium silicate was added with heating and stirring at 80 ° C. or higher, and the pH was adjusted to 6 to 8 with sulfuric acid. A pigment was obtained. This was further fired at 500 ° C. for 2 hours to obtain an ultraviolet ray blocking agent having a three-layer structure.

<Production example 2 of ultraviolet blocking agent> 488 g of cerium chloride CeCl ₃ is dissolved in water to prepare 3.3 liter of cerium chloride solution. Also, sodium hydroxide Na
2. Dissolve 237 g of OH in water and add sodium hydroxide solution.
Prepare 3 liters. 7. Water heated to 30-40 ° C
The cerium chloride solution and the sodium hydroxide solution were added to 5 liters with stirring, and the pH after the reaction was 9 to 11 and the temperature was 5
Add dropwise simultaneously so that the temperature can be kept at 0 ° C or lower. After the dropping of both solutions is completed, stirring is continued for 30 minutes, and then the pH of the reaction solution is readjusted to 5 or more. The resulting cerium hydroxide slurry is decanted and washed with water 4 to 5 times to prepare a cerium hydroxide slurry. Sodium silicate solution 56
2 g (SiO ₂ content 28.5% by weight) is dissolved in water to prepare 2 liter of sodium silicate solution. 95% by weight
Is diluted with water to prepare 2 liter of dilute sulfuric acid solution. While heating and stirring the cerium hydroxide slurry at 80 ° C. or higher, a sodium silicate solution and a dilute sulfuric acid solution are simultaneously added dropwise so that the pH of the reaction solution can be maintained at 9 or higher. After the dropping of both solutions is completed, stirring is continued for 30 minutes, and then the reaction solution is prepared with dilute sulfuric acid so that the pH of the reaction solution becomes 7 to 8. This is filtered, washed with water, dried and pulverized to obtain S having a two-layer structure.
Cerium oxide / amorphous silica composite particles containing 32% by weight of iO ₂ were obtained.

<Manufacture of Thermosensitive Recording Material> Examples 1 to 15 and Comparative Examples 1 to 28 Hereinafter, the thermosensitive recording material of the present invention will be described with reference to Examples.
In the description, parts and% indicate parts by weight and% by weight, respectively.
The compounds used in the thermosensitive recording materials of the present example and the comparative example are compounds (A-1), (A-2),
(A-10), (A-12), (A-19), (A-2)
5), bisphenol A (BPA), 4-hydroxy-
Any of 4'-isopropoxydiphenyl sulfone (D-8), and 3-diethylamino-6 as a dye precursor
-Methyl-7-anilinofluoran (ODB).
The developer dispersion (solution A) and the dye precursor dispersion (solution B) having the following composition were separately wet-ground using a sand grinder until the average particle diameter became 1 μm. Solution A (Developer dispersion) Developer 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Solution B (Dye precursor dispersion) 3-Diethylamino-6-methyl-7-ani Linofluoran (ODB) 2.0 parts 10% aqueous solution of polyvinyl alcohol 4.6 parts Water 2.6 parts

A dispersion was prepared by wet grinding with a sand grinder until the average particle diameter became 1 μm with the following composition of an ultraviolet absorber. Liquid C (UV absorber dispersion liquid 1) 2- (2'-hydroxy-5'-methylphenyl) benzotriazole 5 parts 3% aqueous polyvinyl alcohol solution 1 part Water 20 parts Liquid D (UV absorber dispersion liquid 2) 2, 2-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] 1.0 part 10% aqueous solution of polyvinyl alcohol 2.0 parts Water 4 0.0 part E liquid (ultraviolet absorber dispersion liquid 2) 2,2-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] 3.0 parts 10% aqueous solution of polyvinyl alcohol 6.0 parts Water 12.0 parts Liquid F (UV absorber dispersion liquid 1) 2- (2'-hydroxy-5'-methylphenyl) benzotriazole 1.0 3% aqueous solution of polyvinyl alcohol 0.2 part Water 5.0 parts Liquid G (UV absorber dispersion liquid 3) 2,4-dihydroxybenzophenone 1.0 part 10% aqueous solution of polyvinyl alcohol 2.0 parts Water 4.0 parts H liquid (Ultraviolet absorber dispersion liquid 4) 2-hydroxy-4-octyloxybenzophenone 1.0 part 10% aqueous polyvinyl alcohol solution 2.0 parts Water 4.0 parts I liquid (ultraviolet absorber dispersion liquid 2) 2,2-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] 5.0 parts 10% aqueous solution of polyvinyl alcohol 10.0 parts Water 20.0 parts

[Example 1] (1) Formation of undercoat layer A dispersion was mixed at the following ratio to prepare an undercoat layer coating solution. Liquid C (UV absorber dispersion liquid 1) 26 parts 10% polyvinyl alcohol aqueous solution 150 parts Calcined kaolin (40% dispersion liquid) 250 parts The above coating liquid is applied 50 g / m ² on one side of a base paper 5.0 g.
/ M ² , and then dried to form an undercoat layer. (2) Formation of heat-sensitive recording layer A dispersion was mixed at the following ratio to prepare a heat-sensitive layer coating solution. Solution A (Developer Dispersion [A-1] Dispersion) 36.0 parts Solution B (Dye Precursor [ODB] Dispersion) 9.2 parts UV blocking agent of Production Example 1 (three-layer structure) (30 % Dispersion) (The flake pigment serving as a nucleus is silica) 10.0 parts D liquid (ultraviolet absorber dispersion 2) 7.0 parts Kaolin clay (50% dispersion) 12.0 parts The heat-sensitive recording layer was formed on the coating layer by applying and drying so that the coating amount was 6.0 g / m ² . (3) Preparation of protective layer A dispersion was mixed at the following ratio to obtain a coating liquid. 10% aqueous solution of polyvinyl alcohol 60.0 parts Aluminum hydroxide (50% dispersion) 30.0 parts Zinc stearate 10.0 parts Fluorescent dye (diaminostilbene disulfonic acid derivative; Tinopal ABPliq. Manufactured by Ciba Geigy) 0.5 part Water 70 0.0 part of the coating solution was applied onto the heat-sensitive recording layer so as to have a coating amount of 4.0 g / m ² , dried and then subjected to a super calender treatment to obtain a heat-sensitive recording material.

Example 2 A heat-sensitive recording medium was obtained in the same manner as in Example 1, except that the developer dispersion was changed from A-1 to A-10.

Example 3 A heat-sensitive recording medium was obtained in the same manner as in Example 1, except that the developer dispersion was changed from A-1 to A-19.

Example 4 In the heat-sensitive recording medium of Example 1, the ultraviolet blocking agent (three-layer structure) of Production Example 1 was used.
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the ultraviolet ray blocking agent (two-layer structure) was used.

Example 5 In the heat-sensitive recording medium of Example 2, the ultraviolet blocking agent (three-layer structure) of Production Example 1 was used.
A heat-sensitive recording material was obtained in the same manner as in Example 2, except that the ultraviolet ray blocking agent of (two-layer structure) was used.

Example 6 In the heat-sensitive recording medium of Example 3, the ultraviolet blocking agent of Production Example 1 (three-layer structure) was used.
A heat-sensitive recording material was obtained in the same manner as in Example 3 except that the ultraviolet ray blocking agent (two-layer structure) was used.

Example 7 A heat-sensitive recording medium was obtained in the same manner as in Example 2, except that the heat-sensitive recording layer was changed as follows. (2) Formation of heat-sensitive recording layer A dispersion was mixed at the following ratio to prepare a heat-sensitive layer coating solution. Solution A (Developer Dispersion [A-10] Dispersion) 36.0 parts Solution B (Dye Precursor [ODB] Dispersion) 9.2 parts UV blocking agent of Production Example 1 (three-layer structure) (30) % Dispersion) (The flake pigment serving as a nucleus is silica) 10.0 parts Kaolin clay (50% dispersion) 12.0 parts Each of the above coating solutions is applied to the undercoat layer in an amount of 6.0 g / m ² . To form a heat-sensitive recording layer.

Example 8 A heat-sensitive recording medium was obtained in the same manner as in Example 7, except that the developer in the heat-sensitive recording layer was changed from A-10 to A-12. Was.

Example 9 In the heat-sensitive layer of Example 1,
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the heat-sensitive recording layer and the protective layer were changed as follows. (2) Formation of heat-sensitive recording layer A dispersion was mixed at the following ratio to prepare a heat-sensitive layer coating solution. Liquid A (developer dispersion [A-1] dispersion) 36.0 parts Liquid B (dye precursor [ODB] dispersion) 9.2 parts Liquid D (ultraviolet absorber dispersion 2) 7.0 parts Kaolin clay (50% dispersion) 12.0 parts Each of the above coating solutions was applied on the undercoat layer so as to have a coating amount of 6.0 g / m ² and dried to form a heat-sensitive recording layer. (3) Formation of protective layer A dispersion was mixed at the following ratio to obtain a coating liquid. 10% aqueous solution of polyvinyl alcohol 60.0 parts Aluminum hydroxide (50% dispersion) 30.0 parts Zinc stearate 10.0 parts UV blocking agent of Production Example 1 (30% dispersion) (three-layer structure) Flake pigment is silica) 30.0 parts Fluorescent dye (diaminostilbene disulfonic acid derivative; Tinopal ABPliq. Manufactured by Ciba Geigy) 0.5 part Water 50.0 parts Coating amount of the above coating solution on heat-sensitive recording layer 4.0 g / After applying and drying to obtain m ² , a super calender treatment was performed to obtain a thermosensitive recording medium.

Example 10 A heat-sensitive recording material was obtained in the same manner as in Example 9, except that the developer in the heat-sensitive recording layer was changed from A-1 to A-12. Was.

Example 11 A heat-sensitive recording material was obtained in the same manner as in Example 9 except that the heat-sensitive recording layer of the heat-sensitive recording material of Example 9 was changed as follows. (2) Formation of heat-sensitive recording layer A dispersion was mixed at the following ratio to prepare a heat-sensitive layer coating solution. Solution A (Developer dispersion [A-2] dispersion) 36.0 parts Solution B (Dye precursor [ODB] dispersion) 9.2 parts Kaolin clay (50% dispersion) 12.0 parts Each of the above The coating solution was applied onto the undercoat layer so as to have a coating amount of 6.0 g / m ² and dried to form a heat-sensitive recording layer.

Example 12 A heat-sensitive recording material was obtained in the same manner as in Example 11, except that the developer in the heat-sensitive recording layer was changed from A-2 to A-19. Was.

Example 13 A thermosensitive recording medium was obtained in the same manner as in Example 2, except that the thermosensitive recording layer and the protective layer were changed as follows. (2) Formation of heat-sensitive recording layer A dispersion was mixed at the following ratio to prepare a heat-sensitive layer coating solution. Solution A (Developer dispersion [A-10] dispersion) 36.0 parts Solution B (Dye precursor [ODB] dispersion) 9.2 parts Kaolin clay (50% dispersion) 12.0 parts Each of the above The coating solution was applied onto the undercoat layer so as to have a coating amount of 6.0 g / m ² and dried to form a heat-sensitive recording layer. (3) Formation of protective layer A dispersion was mixed at the following ratio to obtain a coating liquid. 10% aqueous solution of polyvinyl alcohol 60.0 parts Aluminum hydroxide (50% dispersion) 30.0 parts Zinc stearate 10.0 parts UV blocking agent of Production Example 1 (30% dispersion) (three-layer structure) Flake pigment is silica) 30.0 parts Fluorescent dye (diaminostilbene disulfonic acid derivative; Tinopal ABPliq. Manufactured by Ciba Geigy) 0.5 part Water 50.0 parts Coating amount of the above coating solution on heat-sensitive recording layer 4.0 g / After applying and drying to obtain m ² , a super calender treatment was performed to obtain a thermosensitive recording medium.

Example 14 For the heat-sensitive recording material of Example 13, the color developer in the heat-sensitive recording layer was changed from A-10 to A-25.
A thermosensitive recording medium was obtained in the same manner as in Example 13 except that the temperature was changed.

Example 15 A heat-sensitive recording medium was obtained in the same manner as in Example 1, except that the solution D in the heat-sensitive recording layer was changed to the solution E.

Example 16 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that the solution D in the heat-sensitive recording layer was replaced with the solution F.

Comparative Example 1 (1) Formation of Undercoat Layer A dispersion was mixed at the following ratio to prepare an undercoat layer coating liquid. 10% aqueous solution of polyvinyl alcohol 150 parts Calcined kaolin (40% dispersion) 250 parts The above coating solution is applied on one side of 50 g / m ² base paper 5.0 g.
/ M ² , and then dried to form an undercoat layer. (2) Formation of heat-sensitive recording layer A dispersion was mixed at the following ratio to prepare a heat-sensitive layer coating solution. Solution A (Developer dispersion [A-1] dispersion) 36.0 parts Solution B (Dye precursor [ODB] dispersion) 9.2 parts Kaolin clay (50% dispersion) 12.0 parts Each of the above The coating solution was applied onto the undercoat layer so as to have a coating amount of 6.0 g / m ² and dried to form a heat-sensitive recording layer. (3) Preparation of protective layer A dispersion was mixed at the following ratio to obtain a coating liquid. 10% aqueous solution of polyvinyl alcohol 60.0 parts Aluminum hydroxide (50% dispersion) 30.0 parts Zinc stearate 10.0 parts Water 70.0 parts Coating amount of the above coating solution on heat-sensitive recording layer 4.0 g / m After coating and drying so as to obtain No. ² , a super calender treatment was performed to obtain a thermosensitive recording medium.

Comparative Example 2 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 1 except that the developer in the thermosensitive recording layer was changed from A-1 to A-10. Was.

Comparative Example 3 A heat-sensitive recording material was obtained in the same manner as in Comparative Example 1 except that the developer in the heat-sensitive recording layer was changed from A-1 to A-19. Was.

Comparative Example 4 A heat-sensitive recording medium was obtained in the same manner as in Comparative Example 2, except that the undercoat layer coating solution was changed as follows. (1) Formation of Undercoat Layer The dispersion liquid was mixed at the following ratio to prepare an undercoat layer coating liquid. Liquid C (UV absorber dispersion liquid 1) 26 parts 10% polyvinyl alcohol aqueous solution 150 parts Calcined kaolin (40% dispersion liquid) 250 parts The above coating liquid is applied 50 g / m ² on one side of a base paper 5.0 g.
/ M ² , and then dried to form an undercoat layer.

Comparative Example 5 A heat-sensitive recording material was obtained in the same manner as in Comparative Example 4, except that the developer in the heat-sensitive recording layer was changed from A-10 to A-12. Was.

Comparative Example 6 A heat-sensitive recording medium was obtained in the same manner as in Comparative Example 1, except that the heat-sensitive recording layer was changed as follows. (2) Formation of heat-sensitive recording layer A dispersion was mixed at the following ratio to prepare a heat-sensitive layer coating solution. Liquid A (developer dispersion [A-10] dispersion) 36.0 parts Liquid B (dye precursor [ODB] dispersion) 9.2 parts Liquid D (ultraviolet absorber dispersion 2) 7.0 parts Kaolin clay (50% dispersion) 12.0 parts Each of the above coating solutions was applied onto the undercoat layer so as to have a coating amount of 6.0 g / m ² and dried to form a heat-sensitive recording layer.

Comparative Example 7 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 6, except that the developer in the thermosensitive recording layer was changed from A-10 to A-25. Was.

Comparative Example 8 A heat-sensitive recording medium was obtained in the same manner as in Comparative Example 6, except that the UV absorbent in the heat-sensitive recording layer was changed from D-solution to G-solution.

Comparative Example 9 A heat-sensitive recording medium was obtained in the same manner as in Comparative Example 6, except that the UV absorber in the heat-sensitive recording layer was changed from the D solution to the H solution.

Comparative Example 10 A thermal recording medium was obtained in the same manner as in Comparative Example 6, except that the thermal recording layer of the thermal recording medium of Comparative Example 6 was changed as follows. (2) Formation of heat-sensitive recording medium Liquid A (developer dispersion [A-10] dispersion) 36.0 parts Liquid B (dye precursor [ODB] dispersion) 9.2 parts Liquid I (ultraviolet absorber) Dispersion liquid 2) 35.0 parts Kaolin clay (50% dispersion liquid) 12.0 parts Each of the above coating liquids was applied on the undercoat layer so as to have a coating amount of 6.0 g / m ² and dried to form a heat-sensitive recording layer. Formed.

Comparative Example 11 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 1, except that the heat-sensitive recording layer was changed as follows. (2) Formation of heat-sensitive recording layer A dispersion was mixed at the following ratio to prepare a heat-sensitive layer coating solution. Solution A (Developer Dispersion [A-10] Dispersion) 36.0 parts Solution B (Dye Precursor [ODB] Dispersion) 9.2 parts UV blocking agent of Production Example 1 (three-layer structure) (30) % Dispersion) (The flake pigment serving as a nucleus is silica) 10.0 parts Kaolin clay (50% dispersion) 12.0 parts Each of the above coating solutions is applied to the undercoat layer in an amount of 6.0 g / m ² . To form a heat-sensitive recording layer.

[Comparative Example 12] With respect to the heat-sensitive recording medium of Comparative Example 11, the developers in the heat-sensitive recording layer were A-10 to A-19.
A thermosensitive recording medium was obtained in the same manner as in Comparative Example 11 except that the temperature was changed.

Comparative Example 13 Comparative Example 11 was the same as Comparative Example 11, except that the UV-blocking agent of Production Example 1 (three-layer structure) in the heat-sensitive recording layer was replaced with the UV-blocking agent of Production Example 2 (two-layer structure). In the same manner as in No. 11, a thermal recording medium was obtained.

Comparative Example 14 Comparative Example 12 was the same as Comparative Example 12, except that the ultraviolet ray blocking agent of Production Example 1 (three-layer structure) in the heat-sensitive recording layer was replaced with the ultraviolet ray blocking agent of Production Example 2 (two-layer structure). In the same manner as in Example 12, a thermosensitive recording medium was obtained.

Comparative Example 15 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 1, except that the protective layer was changed as follows. (3) Preparation of protective layer A dispersion was mixed at the following ratio to obtain a coating liquid. 10% aqueous solution of polyvinyl alcohol 60.0 parts Aluminum hydroxide (50% dispersion) 30.0 parts Zinc stearate 10.0 parts Fluorescent dye (diaminostilbene disulfonic acid derivative; Tinopal ABPliq. Manufactured by Ciba Geigy) 0.5 part Water 70 0.0 part of the coating solution was applied onto the heat-sensitive recording layer so as to have a coating amount of 4.0 g / m ² , dried and then subjected to a super calender treatment to obtain a heat-sensitive recording material.

Comparative Example 16 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 15 except that the developer in the thermosensitive recording layer was changed from A-1 to A-10 in the thermosensitive recording medium of Comparative Example 15. Was.

[Comparative Example 17] In Comparative Example 1, the protective layer was changed as follows, and the developers in the heat-sensitive layer were changed from A-1 to A.
A thermosensitive recording medium was obtained in the same manner as in Comparative Example 1 except that the composition was changed to -2. (3) Formation of protective layer A dispersion was mixed at the following ratio to obtain a coating liquid. 10% aqueous solution of polyvinyl alcohol 60.0 parts Aluminum hydroxide (50% dispersion) 30.0 parts Zinc stearate 10.0 parts UV blocking agent of Production Example 1 (30% dispersion) (three-layer structure) 30.0 parts Water 50.0 parts The above coating solution was applied on the heat-sensitive recording layer so as to have a coating amount of 4.0 g / m ² , dried and then subjected to a super calender treatment to obtain a heat-sensitive recording material. Obtained.

Comparative Example 18 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 17 except that the developer in the thermosensitive recording layer was changed from A-2 to A-10 in the thermosensitive recording medium of Comparative Example 17. Was.

[Comparative Example 19] In Example 7, the protective layer was changed as follows, and the developer in the heat-sensitive recording layer was changed to A-10.
A thermosensitive recording medium was obtained in the same manner as in Example 7 except that the composition was changed to A-2. (3) Preparation of protective layer A dispersion was mixed at the following ratio to obtain a coating liquid. 10% aqueous solution of polyvinyl alcohol 60.0 parts Aluminum hydroxide (50% dispersion) 30.0 parts Zinc stearate 10.0 parts Water 70.0 parts Coating amount of the above coating solution on heat-sensitive recording layer 4.0 g / m After coating and drying so as to obtain No. ² , a super calender treatment was performed to obtain a thermosensitive recording medium.

Comparative Example 20 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 19, except that the developer in the thermosensitive recording layer was changed from A-2 to A-10 in the thermosensitive recording medium of Comparative Example 19. Was.

Comparative Example 21 A thermosensitive recording medium was obtained in the same manner as in Example 1, except that the heat-sensitive recording layer was changed as follows. (2) Formation of heat-sensitive recording layer A dispersion was mixed at the following ratio to prepare a heat-sensitive layer coating solution. Solution A (Developer dispersion [A-10] dispersion) 36.0 parts Solution B (Dye precursor [ODB] dispersion) 9.2 parts Kaolin clay (50% dispersion) 12.0 parts Each of the above The coating solution was applied onto the undercoat layer so as to have a coating amount of 6.0 g / m ² and dried to form a heat-sensitive recording layer.

Comparative Example 22 A heat-sensitive recording medium was obtained in the same manner as in Comparative Example 21, except that the developer in the heat-sensitive recording layer was changed from A-10 to A-25. .

Comparative Example 23 A heat-sensitive recording material was obtained in the same manner as in Example 7, except that the undercoat layer was changed as follows. (1) Formation of Undercoat Layer The dispersion liquid was mixed at the following ratio to prepare an undercoat layer coating liquid. 10% aqueous solution of polyvinyl alcohol 150 parts Calcined kaolin (40% dispersion) 250 parts The above coating solution is applied on one side of 50 g / m ² base paper 5.0 g.
/ M ² , and then dried to form an undercoat layer.

Comparative Example 24 A heat-sensitive recording medium was obtained in the same manner as in Comparative Example 23, except that the developer in the heat-sensitive recording layer was changed from A-10 to A-12. .

Comparative Example 25 A thermosensitive recording medium was prepared in the same manner as in Comparative Example 4 except that the developer in the heat-sensitive recording layer was changed from A-10 to A-1 and the protective layer was changed as follows. A recording was obtained. (3) Preparation of protective layer A dispersion was mixed at the following ratio to obtain a coating liquid. 10% aqueous solution of polyvinyl alcohol 60.0 parts Aluminum hydroxide (50% dispersion) 30.0 parts Zinc stearate 10.0 parts Liquid C (UV absorber dispersion 1) 26.0 parts Fluorescent dye (diaminostilbene disulfonic acid) Derivative; Ciba-Geigy Tinopal ABPliq.) 0.5 part Water 70.0 parts The above coating solution is applied and dried on the heat-sensitive recording layer so as to have a coating amount of 4.0 g / m ² , and then subjected to a super calendering treatment to be subjected to heat-sensitive recording. I got

Comparative Example 26 A thermosensitive recording medium was obtained in the same manner as in Comparative Example 25 except that the developer in the thermosensitive recording layer was changed from A-1 to A-10 in the thermosensitive recording medium of Comparative Example 25. Was.

[Comparative Example 27] A thermosensitive recording medium was obtained in the same manner as in Comparative Example 25 except that the developer in the thermosensitive recording layer was changed from A-1 to A-19 in the thermosensitive recording medium of Comparative Example 25. Was.

Comparative Example 28 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that the developer in the heat-sensitive recording layer was changed from A-1 to BPA: bisphenol A.

Comparative Example 29 Example 1 was repeated except that the developer in the heat-sensitive recording layer was changed from A-1 to D-8: 4-hydroxy-4'-isopropoxydiphenylsulfone. In the same manner as in the above, a thermosensitive recording medium was obtained.

<Evaluation of Thermosensitive Recording Materials; Examples 1 to 16, Comparative Examples 1 to 29> The thermosensitive recording materials of Examples 1 to 16 and Comparative Examples 1 to 29 were subjected to a thermal recording test and thermal stability of ground color. A test and a light fastness test were performed (see Tables 1 to 6). [Heat Sensitive Recording Test (Dynamic Coloring Density)] Using a printer of a personal word processor Rupo-90FII (manufactured by Toshiba Corporation) and applying the maximum applied energy, the above Examples 1 to 16 were used.
Thermal recording was performed on the thermal recording media of Comparative Examples 1 to 28 (the same conditions were used for the thermal recording described below). The recording density of the recording portion was measured by a Macbeth densitometer (RD-914, using an amber filter, the same conditions hereinafter). In the thermosensitive recording materials of Examples 1 to 16 using the compound of the present invention as a color developer, a sufficient recording density was obtained by the printer.

[Ground Thermal Stability Test] Using a gear type aging tester (Toyo Seiki Seisaku-sho, Ltd.), a test temperature of 10
The heat resistance tests at 0 ° C., 120 ° C., 30 minutes each, and 140 ° C. for 1 minute were conducted in Examples 1 to 16 and Comparative Examples 1 to 16.
28 heat-sensitive recording media. After the heat resistance test, the density of the ground color was measured with a Macbeth densitometer. In this case, the smaller the value of the Macbeth density, the less the ground color is developed, and the higher the thermal stability of the ground color. In the heat-sensitive recording materials of Examples 1 to 16 using the compound of the present invention as a color developer, the density of the ground color hardly exceeded 0.4 even after 1 minute at 140 ° C and 30 minutes at 120 ° C. In contrast, the thermal recording papers using the phenolic developers of Comparative Examples 28 and 29 already exceeded 0.5 at 100 ° C. for 30 minutes. Actual thermal lamination is usually 100 to 140 ° C and feed rate is 1 to 100 mm / sec.
Therefore, the thermal recording materials of Examples 1 to 16 show that the contrast between the recorded image and the ground color is sufficiently high even after the thermal lamination.

[Image Thermal Stability Test] Using a gear type aging tester (Toyo Seiki Seisakusho), test temperature 90
A heat resistance test at 5 ° C. for 5 minutes was performed on the thermosensitive recording media of Examples 1 to 16 and Comparative Examples 1 to 28. After the heat resistance test,
The image density was measured with a Macbeth densitometer. In this case, the larger the value of the Macbeth density, the higher the thermal stability of the image. The heat-sensitive recording materials of Examples 1 to 16 satisfying the requirements of the present invention had almost the same image density after 90 ° C. for 5 minutes as before the test, but contained an ultraviolet absorber in the heat-sensitive recording layer or the protective layer. Comparative Examples 6 to 10 and Comparative Examples 25 to
At 27, the image density is greatly reduced.

[Light Resistance Test] The heat-sensitive recording materials of Examples, Comparative Examples, and unprinted heat-sensitive recording materials which had already been subjected to the heat-recording under the conditions described above were subjected to a fade meter (BH, manufactured by Toyo Seiki) for 12 hours. The density was measured with a Macbeth densitometer, and the density of the unprinted portion was measured with a Macbeth densitometer yellow position. Examples 1 to 16 of the present invention have image storability by light,
Although the ground color stability is excellent, Comparative Examples 10 and 25 to 29 containing a large amount of an ultraviolet absorber in the heat-sensitive coloring layer.
In all of the comparative examples except for, it is shown that both the image storability by light and the ground color stability are inferior.

[0120]

Table 1 Table 1 Quality test of heat-sensitive recording materials of Examples 1 to 16

Table 2 Quality test results of the heat-sensitive recording materials of Examples 1 to 16

[0122]

Table 3 Quality test of heat-sensitive recording media of Comparative Examples 1 to 14

[0123]

[Table 3] Table 4 Quality test of thermal recording media of Comparative Examples 15 to 29

[0124]

Table 5 Quality test results of the heat-sensitive recording media of Comparative Examples 1 to 14

[0125]

Table 6 Table 6 Quality test results of heat-sensitive recording media of Comparative Examples 15 to 29

[0126]

As described above, the compound represented by the general formula (1) or (2) is used as a color developer, and the undercoat layer and / or the heat-sensitive recording layer contains an ultraviolet absorber. The heat-sensitive recording material of the present invention, which contains an ultraviolet ray blocking agent in the thermosensitive coloring layer and / or the protective layer and contains a fluorescent dye in the protective layer, has a ground color even under a high temperature environment of about 120 to 140 ° C. It has almost no fogging and excellent preservability of the image area, and can provide an image recording density sufficient for practical use with a thermal recording apparatus such as a thermal head. And,
The heat-sensitive recording medium of the present invention has high light resistance.

The effects of the present invention include the following. (1) A thermosensitive recording medium can be used under severe temperature conditions (for example, 90 to 140 ° C.). (2) Thermal lamination can be performed on a thermosensitive recording medium that has been recorded by a laminator. (3) Since the ground color is stable even after passing through a heat roll, it can be used as electrophotographic copying machine paper. (4) Even for use outdoors, it can be used without discoloration or fading.

Continued on the front page (72) Inventor Yutaka Wakita 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo Inside Japan Product Research Laboratory

Claims (10)

[Claims] 1. A heat-sensitive recording medium comprising a support and an undercoat layer, a heat-sensitive recording layer containing a colorless or light-colored dye precursor and a color developer as main components, and a protective layer, which are successively provided. The colorant contains at least one compound represented by the following general formula (1), and the undercoat layer and / or the heat-sensitive recording layer contains an ultraviolet absorber, and the heat-sensitive recording layer and / or A heat-sensitive recording material comprising an ultraviolet ray blocking agent in a protective layer and a fluorescent dye in the protective layer. Embedded image (Wherein, X represents an oxygen atom or a sulfur atom;
Represents an unsubstituted or substituted phenyl group, naphthyl group, aralkyl group, lower alkyl group having 1 to 6 carbon atoms, cycloalkyl group, or lower alkenyl group having 2 to 6 carbon atoms. Z represents a lower alkyl group having 1 to 6 carbon atoms or an electron-withdrawing group. n represents the integer of 0-4. ) 2. The heat-sensitive recording medium according to claim 1, wherein the developer contains at least one compound represented by the following general formula (2). Embedded image (In the formula, Y represents a lower alkyl group having 1 to 6 carbon atoms or an electron-withdrawing group. M represents an integer of 0 to 3.) 3. The ultraviolet blocking agent has a refractive index of 1.5 to 1.
3. The heat-sensitive recording material according to claim 1, comprising a baked product of particles having a three-layer structure in which the surface of the flake pigment is coated with an insoluble cerium compound and amorphous silica. 4. The heat-sensitive recording material according to claim 1, wherein the ultraviolet ray blocking agent comprises a fired product of particles having a two-layer structure in which an insoluble cerium compound is coated with amorphous silica. 5. The thermosensitive recording medium according to claim 1, wherein the ultraviolet absorber is a benzotriazole compound. 6. The amount of the ultraviolet absorber contained in the undercoat layer and / or the heat-sensitive recording layer is 0.1% by weight to 15% by weight based on the dry weight of the undercoat layer, and The heat-sensitive recording material according to any one of claims 1 to 5, wherein the content is 0.1% by weight to 8% by weight. 7. The thermosensitive recording medium according to claim 1, wherein the melting point of the ultraviolet absorbent contained in the thermosensitive recording layer is 180 ° C. or higher. 8. The content of the ultraviolet ray blocking agent contained in the heat-sensitive recording layer and / or the protective layer is 10% by weight to 40% by weight with respect to the dry weight of the heat-sensitive recording layer, and 5% by weight with respect to the dry weight of the protective layer. The heat-sensitive recording material according to any one of claims 1 to 7, wherein the content of the heat-sensitive recording material is from 10% to 40% by weight. 9. The heat-sensitive recording material according to claim 1, wherein the content of the fluorescent dye contained in the protective layer is 0.01 to 3% by weight based on the dry weight of the protective layer. 10. A thermosensitive recording medium according to claim 1, wherein the recording surface of the thermosensitive recording medium or the entire recording body is laminated with a plastic film.