JPH09286180A - Thermal recording body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording body in which light resistance and chemical resistance of a recording part and an unrecorded part are excellent and also recording traveling properties are excellent. SOLUTION: This thermal recording body is constituted so as to successively provide both a thermal recording layer which contains a colorless or light- colored basic dye and a colorant and protective layer containing an ultraviolet absorbent on a supporting body. In this case, at least one kind selected from among 3-di-n-buthylamino-7-(o-chloroanilino) fluoran, 3-diethylamino-7-(m- trifluoromethyl) anilinofluoran and 3-di-n-butylamino-6-methyl-7-anilinofluoran is used as the basic dye in the thermal recording layer. 2,2'-Methylenebis[4-tert- butyl-6-(2H-benzotriazole-2-yl)phenol] is used as the ultraviolet absorbent 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 utilizing a color reaction of a colorless or light-colored basic dye and a coloring agent, which is excellent in light resistance of a recorded portion and an unrecorded portion. It is a thing.

[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.

One of the fields of use thereof is, for example, POS.
(Point of sales) Thermal recording labels for systems can be mentioned. With the expansion of the system, labels attached to products for a long period of time are different from the conventional food labels whose mission is completed in a short period of time. The usage as tag paper used or handy terminal paper for collection and delivery that 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 having excellent light resistance, which does not cause fading of a recorded image or yellowing of a background portion even when exposed to room light or sunlight for a long time.

Then, for the purpose of improving the light resistance, a method of adding an ultraviolet absorber into the protective layer is disclosed in JP-A-60-8493.
No. 8, JP-A-60-107388, JP-A-60-
No. 112487, 61-193883, etc. However, since the ultraviolet absorber used in such a protective layer generally has a low melting point (200 ° C. or less), it is melted during recording to cause sticking and head residue between the thermal head and the protective layer, resulting in a uniform recorded image. However, because of high solubility in organic solvents, contact with chemicals such as plasticizers and oils causes problems such as background fog and fading of recorded images.

Further, JP-A-7-47764 describes a heat-sensitive recording material containing a bistriazole compound in the heat-sensitive recording layer, but it is not possible to obtain a sufficient light resistance effect.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording medium which is excellent in light resistance and chemical resistance of a recorded portion and an unrecorded portion and is excellent in recording running property.

[0007]

A heat-sensitive recording material comprising a support and a heat-sensitive recording layer containing a colorless or light-colored basic dye and a coloring agent, and a protective layer containing an ultraviolet absorber, which are provided in this order. The present invention provides, as one means for solving the above problems, 3-di-n-butylamino-7- (o-chloroanilino) fluorane as a basic dye in a thermosensitive recording layer,
3-diethylamino-7- (m-trifluoromethyl)
Anilinofluoran, 3-di-n-butylamino-6-
Methyl-7-anilinofluorane, 2,4-dimethyl-
At least one selected from 6-[(4-dimethylamino) anilino] fluorane is used, and 2,2′-methylenebis [4-tert-butyl-6- (2H-benzotriazole-) is used as an ultraviolet absorber in the protective layer. 2-yl) phenol] is used. Further, as another means, in the above means, the average particle diameter of the ultraviolet absorber is further adjusted to 2 μm or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention comprises at least 3-di-n-butylamino-7-as a basic dye in a heat-sensitive recording layer.
From (o-chloroanilicyl) anilinofluorane, 3-diethylamino-7- (m-trifluoromethyl) anilinofluorane, 3-di-n-butylamino-6-methyl-7-anilinofluorane As a UV absorber in the protective layer, using one of the specific basic dyes selected,
2'-methylenebis [4-tert-butyl-6- (2H-
Benzotriazol-2-yl) phenol] is used, and the average particle size of the specific ultraviolet absorber is preferably 2 μm or less. 2μ
If it exceeds m, the ultraviolet absorption efficiency may decrease. In particular, when the thickness is 0.5 μm or less, not only the ultraviolet absorption efficiency is remarkably improved, but also the protective layer hardly hides the recorded image, so that a clear recorded image is formed. Further, since the specific ultraviolet absorber is hardly dissolved in a solvent such as a plasticizer, an edible oil and an organic solvent, background fog may occur even if the surface of the protective layer is immersed in the solvent, or the recorded image may be discolored. It also has an excellent effect on chemical resistance.

The content of the specific ultraviolet absorber is about 1 to 50% by weight, particularly 10 to 10% by weight based on the total solid content of the protective layer.
About 40% by weight is preferable. When the content of such a specific ultraviolet absorber is less than 1% by weight based on the total solid content of the protective layer, the light resistance of the recorded image is remarkably lowered, and when it exceeds 50% by weight, the film forming property of the protective layer is lowered and the recorded image is lowered. The chemical resistance of is significantly reduced. In addition, as long as the desired effects of the present invention are not impaired, p-tert-butylphenyl salicylate, 2-
(2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) benzotriazole, 2
Other known UV absorbers such as-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole can also be used in combination.

Regarding the amount of the above-mentioned specific ultraviolet absorber used
Cannot be unconditionally determined in relation to the coating amount of the protective layer
Is generally 0.05 to 2.0 g / m in the protective layer.^Two, Preferred
0.2 to 1.0 g / m^TwoIs desirable. Purple in the protective layer
Outside line absorbent is 0.05g / m ^TwoIf less than, thermal recording
The effect of preventing yellowing of unrecorded areas of the body is significantly reduced.
You. Also, 2.0 g / m^TwoIf it exceeds, the protective layer will inevitably
Since the thickness increases, the recording sensitivity decreases.

The average particle diameter of the specific ultraviolet absorber is 2 μm
As a method of refining below, water is generally used as a dispersion medium, and additives such as a dispersant and an antifoaming agent are added as necessary, and the mixture is stirred by a ball mill, attritor, sand mill, or the like.
There are a method using a pulverizer, a method in which an ultraviolet absorber is dissolved in a low boiling point solvent, then emulsified, and the low boiling point solvent is evaporated and removed.
Above all, a sand mill type crusher is desirable, and the average particle diameter of the dispersion medium is preferably 1 mm or less, more preferably 0.5 mm or less.

In addition to a specific ultraviolet absorber, the protective layer may be used as an adhesive such as starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy modified polyvinyl alcohol, aceto. Acetyl group-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, At least one of urea resin, melamine resin, amide resin, polyester urethane resin and the like is used in an amount of about 15 to 80% by weight based on the total solid amount of the protective layer.

Of these, 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 mainly composed of polyvinyl alcohol that has been converted into acetoacetic acid ester. The acetoacetic acid esterification of polyvinyl alcohol is produced by a method of adding diketene to a polyvinyl alcohol resin or transesterifying acetoacetic acid ester. The degree of polymerization of this polymer is 200 to 200.
About 0 is desirable.

If necessary, a pigment may be added to the protective layer in order to improve printability and sticking. Specific examples of the pigment include calcium carbonate, zinc oxide, aluminum oxide, titanium dioxide, silicon dioxide, aluminum hydroxide, barium sulfate, talc, kaolin,
Examples thereof include inorganic pigments such as clay, calcined kaolin and colloidal silica, organic pigments such as styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, and raw starch particles.

Further, in the protective layer, if necessary, a lubricant such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, etc., and a surfactant (dispersion, wetting agent, etc.) such as sodium dioctylsulfosuccinate. ), Antifoaming agents, and various auxiliaries such as water-soluble polyvalent metal salts such as potassium alum and aluminum acetate can be appropriately added. Also, in order to further improve water resistance, glyoxal, boric acid,
A curing agent such as dialdehyde starch or an epoxy compound can be used, and a microencapsulated UV absorber or the like can be used in combination, if necessary.

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 in addition to a specific ultraviolet absorber and an adhesive, a pigment, a lubricant, etc. which are added as necessary. Is prepared by mixing and stirring.

In the heat-sensitive recording layer, 3-di-n-butylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7- (m-trifluoromethyl) anilinofluorane, and 3 are used as basic dyes. By using at least one selected from -di-n-butylamino-6-methyl-7-anilinofluorane and 2,4-dimethyl-6-[(4-dimethylamino) anilino] fluorane, the recording portion and It has excellent light resistance in the unrecorded area, and also has excellent effects on storage characteristics and recording runnability.
Of these, 2,4-dimethyl-6-[(4-dimethylamino) anilino] fluorane is particularly preferable because it is excellent in light resistance.

Further, as long as the desired effects of the present invention are not impaired, 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane, 3- (N
-Cyclohexyl-N-methylamino) -6-methyl-
7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3-
It is also possible to use together with other known basic dyes such as diethylamino-6-methyl-7-anilinofluorane.

Various known coloring agents can be used in combination with the specific basic dye, for example, 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-hydroxyphenylthio) Ethoxy) 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-chlorophenylthiourea, zinc p-chlorobenzoate,
Zinc 4- [2-p-methoxyphenoxyethoxy] salicylate, zinc 4- [3- (p-tolylsulfonyl) propyloxy] salicylate, zinc 5- [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylate, etc. Examples thereof include zinc salts of aromatic carboxylic acids. Of these, 4-hydroxy-4′-isopropoxydiphenyl sulfone and bis (3-allyl-4-hydroxyphenyl) sulfone are particularly preferably used because they are particularly excellent in the preservation of recorded images.

The use ratio of the specific basic dye and the color developing agent is appropriately selected according to the type of the specific basic dye or color developing agent, and is not particularly limited, but generally a base is used. About 1 to 10 parts by weight, preferably about 2 to 5 parts by weight, of a coloring agent is used with respect to 1 part by weight of the functional dye. The amount of the specific basic dye used is about 5 to 40% by weight based on the total solid amount of the heat-sensitive recording layer.

Further, in the heat-sensitive recording layer, a sensitizer for increasing recording sensitivity and a preservative improving agent for improving preservability of a recorded image with time can be used in combination. Specific examples of the sensitizer include, for example, stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, ethylenebisstearic acid, methylenebisstearic acid amide, N-
Methylol stearate amide, dibenzyl terephthalate, p-benzyloxybenzoate benzyl, 2-naphthylbenzyl ether, m-terphenyl, dibenzyl oxalate, oxalate-di-p-methylbenzyl, oxalate-di-p-chloro. Benzyl, p-benzylbiphenyl,
Di (p-methoxyphenoxyethyl) ether, 1,2
-Di (3-methylphenoxy) ethane, 1,2-di (4
-Methylphenoxy) ethane, 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-
Examples thereof include p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane and the like. The amount of these sensitizers used is not particularly limited,
Generally, it is desirable to adjust the amount of the coloring agent in the range of about 4 parts by weight or less relative to 1 part by weight.

Specific examples of the storability improver include the following. 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'-tetramethyldiphenyl sulfone, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-
Hindered phenol compounds such as bis (4-hydroxy-3,5-dimethylphenyl) propane, 1,4-diglycidyloxybenzene, 4,4′-diglycidyloxydiphenyl sulfone, 4-benzyloxy-4′-
(2-methylglycidyloxy) diphenyl sulfone,
Epoxy compounds such as diglycidyl terephthalate, cresol novolac type epoxy resin, phenol novolac type epoxy resin, and bisphenol A type epoxy resin,
N, N'-di-2-naphthyl-p-phenyldiamine,
Sodium or polyvalent metal salt of 2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate,
Bis (4-ethyleneiminocarbonylaminophenyl)
Such as methane. Among them, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane is preferably used because it has an excellent water resistance effect and does not easily cause background fog.

A coating solution for a heat-sensitive recording layer, which contains a specific basic dye, a color former, and optionally a sensitizer and a storability improver, generally uses water as a dispersion medium and is used in a ball mill, an attritor, a sand mill or the like. Basic dye,
A colorant, a sensitizer, a storability improver, etc. are finely dispersed together or separately, and an adhesive and, if necessary, a pigment, a lubricant, a surfactant, an antifoaming agent, a colored dye, etc. are added. Is prepared.

Specific examples of the adhesive include 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, diisobutylene / maleic anhydride copolymer salt, styrene / maleic anhydride copolymer salt , Ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene / butadiene copolymer emulsion, urea resin, melamine resin, amide resin, polyurethane resin and the like.
Such an adhesive is used in an amount of 5 to 30 relative to the total solid amount of the heat sensitive recording layer.
It is blended in the range of about wt%.

Specific examples of pigments, lubricants and surfactants include inorganic pigments such as kaolin, clay, calcium carbonate, calcined clay, calcined kaolin, titanium dioxide, diatomaceous earth, fine particulate anhydrous silica, activated clay and styrene microballs. , Nylon powder, polyethylene powder, urea / formalin resin filler, organic pigments such as raw starch particles, zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax, lubricants, sodium dioctyl sulfosuccinate, dodecylbenzene sulfonic acid Examples include surfactants such as sodium, sodium lauryl alcohol sulfate, and fatty acid metal salts.

Regarding the method for forming the heat-sensitive recording layer and the protective layer,
Is not particularly limited, and for example, air knife coating
Coating, varibar coating, pure blade coating
Ring, rod blade coating, short dwell
Coating, curtain coating, die coating
Coating solution for the heat-sensitive recording layer and its retention by an appropriate coating method such as coating.
Coating liquid for protective layer on paper, plastic film, synthetic paper, non-woven
Heat-sensitive by sequentially coating and drying on a cloth or other support
A recording layer and a protective layer are formed. For thermal recording layer
The coating amount of the coating liquid is 2 to 12 g / m as a dry weight.^Two, Preferably
Is 3 to 10 g / m ^TwoDegree, the coating amount of the protective layer coating liquid is dry
0.5-15g / m by weight^Two, Preferably 1 to 7 g / m
^TwoIt is a degree.

If desired, a protective layer may be provided on the back side of the support to further improve the storability. Furthermore, an undercoat layer may be provided between the support and the thermosensitive recording layer,
After each layer is formed, it is subjected to smoothing treatment such as super calendering, or the back side of the support is treated with an adhesive to process it into an adhesive label, magnetic recording layer or coating layer for printing, and thermal transfer recording. Various well-known techniques in the field of heat-sensitive recording material production, such as provision of layers, can be added as necessary.

[0028]

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 respectively show "weight part" and "weight%" unless there is particular notice.

Preparation of Solution A A composition consisting of 10 parts of 3-di-n-butylamino-6-methyl-7-anilinofluorane, 5 parts of a 5% aqueous solution of methylcellulose and 40 parts of water was used in a sand mill to give an average particle size of It was pulverized to 0.8 μm.

Preparation of Solution B A composition consisting of 30 parts of 4,4′-isopropylidenediphenol, 5 parts of a 5% aqueous solution of methylcellulose, and 80 parts of water was pulverized with a sand mill until the average particle size became 1.2 μm.

Preparation of Solution C A composition consisting of 20 parts of 1,2-di (3-methylphenoxy) ethane, 5 parts of a 5% aqueous solution of methylcellulose and 55 parts of water was pulverized with a sand mill until the average particle size became 0.8 μm. did.

Preparation of Solution D 2,2′-methylenebis [4-tert-butyl-6- (2
H-benzotriazol-2-yl) phenol] 10
Parts, 5 parts of a 5% aqueous solution of methyl cellulose, and 40 parts of water were pulverized with a sand mill until the average particle size became 0.4 μm.

Example 1 [Formation of thermosensitive recording layer] 55 parts of solution A, 115 parts of solution B, 80 parts of solution C, 80 parts of 10% aqueous solution of polyvinyl alcohol and 35 parts of calcium carbonate were mixed and stirred to obtain a heat-sensitive material. The thermosensitive recording layer was formed by coating and drying the coating liquid for a recording layer on one surface of a high-quality paper of 60 g / m ² so that the coating amount after drying was 5 g / m ² .

[Formation of protective layer] 55 parts of D liquid, 150% 10% aqueous solution of acetoacetyl group-modified polyvinyl alcohol
Part, Kaolin [trade name: UW-90, manufactured by EMC] 30
Part, 3 parts of a 10% aqueous solution of glyoxal, 6 parts of a 30% dispersion of zinc stearate, and 30 parts of water were mixed and stirred to obtain a coating solution for a protective layer, which was dried on the thermosensitive recording layer. Was coated and dried so as to have a coating amount of 4 g / m ² to form a protective layer, and then supercalendering was performed to obtain a heat-sensitive recording material.

Examples 2 to 3 Example 1 was repeated except that the following compounds were used in place of 4,4'-isopropylidenediphenol in the preparation of solution B.
A thermosensitive recording medium was obtained in the same manner as described above. Example 2: 4-Hydroxy-4'-isopropoxydiphenyl sulfone Example 3: Bis (3-allyl-4-hydroxyphenyl) sulfone

Examples 4 to 6 In the same manner as in Example 2 except that the following compounds were used in place of 3-di-n-butylamino-6-methyl-7-anilinofluorane in the preparation of solution A. A thermosensitive recording medium was obtained. Example 4: 3-Di-n-butylamino-7- (o-chloroanilino) fluorane Example 5: 3-Diethylamino-7- (m-trifluoromethyl) anilinofluorane Example 6: 2,4- Dimethyl-6-[(4-dimethylamino) anilino] fluorane

Example 7 A thermosensitive recording medium was prepared in the same manner as in Example 1 except that, in the preparation of the D liquid, instead of pulverizing until the average particle size became 0.4 μm, it was pulverized until the average particle size became 1.8 μm. Got

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

Comparative Example 2 In preparation of solution A, 3- (N-cyclohexyl-N-methylamino) -6-methyl- was used instead of 3-di-n-butylamino-6-methyl-7-anilinofluorane. 7-
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that anilinofluoran was used.

Comparative Example 3 In preparation of solution A, 3- (N-ethyl-N-isoamylamino) -6-methyl- was used 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 7-anilinofluorane was used.

Comparative Examples 4 to 5 In the preparation of solution D, 2,2'-methylenebis [4-tert]
-Butyl-6- (2H-benzotriazol-2-yl) phenol] was obtained in the same manner as in Example 1 except that the following compound was used. Comparative Example 4: 2- (2'-hydroxy-5'-methylphenyl) benzotriazole Comparative Example 5: 2,2'-bis [4-tert-octyl-6
-(2H-benzotriazol-2-yl) phenol]

The thermal recording material thus obtained was evaluated as follows, and the obtained results are shown in Table 1.

[Coloring property] Thermosensitive evaluation machine [Product name: TH-P
MD, manufactured by Okura Electric Co., Ltd., and applied energy 0.45
Each thermosensitive recording medium was color-developed at mJ / dot, and the color density of the obtained recorded image was measured by a Macbeth densitometer [RD-914 type, manufactured by Macbeth Co.] in a visual mode.

[Lightfastness] The heat-sensitive recording material recorded in the above-described evaluation of color development was processed by Sunshine Super Long Life Xenon Weather Meter (W.
M. ) For 24 hours, the unrecorded area and the recorded area were measured with a Macbeth densitometer (using a blue filter).

[Plasticizer resistance] Wrap film [Product name: KMA on polycarbonate pulp (40 mmφ tube)]
-W, manufactured by Mitsui Toatsu Kagaku Co., Ltd.) is wound in three layers, the thermal recording material recorded in the above evaluation of the color developability is placed thereon, and a wrap film is further wound in three layers on the thermal recording material, and the film is wrapped at 24 ° C. at The color 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 color develop density after standing at room temperature for 8 hours was measured with a Macbeth densitometer (visual mode), The oil resistance was evaluated.

[Head Matching Property] The stain condition (head residue) of the thermal head after continuous recording for 100 m in the above-mentioned evaluation of color forming property was visually evaluated as follows. Evaluation Criteria ○: No head residue. X: There are many head debris.

[0048]

[Table 1]

[0049]

As is apparent from the results of [Table 1], the thermosensitive recording medium of the present invention is excellent in light resistance and chemical resistance of the recorded portion and the unrecorded portion, and is also excellent in head matching. It was something that had.

Claims (3)

[Claims] 1. A thermosensitive recording medium in which a thermosensitive recording layer containing a colorless or light-colored basic dye and a coloring agent and a protective layer containing an ultraviolet absorber are sequentially provided on a support. Is 3-di-n-butylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7-
(M-Trifluoromethyl) anilinofluorane, 3-
At least one selected from di-n-butylamino-6-methyl-7-anilinofluorane and 2,4-dimethyl-6-[(4-dimethylamino) anilino] fluorane, wherein the ultraviolet absorber is 2 , 2'-methylenebis [4
-Tert-butyl-6- (2H-benzotriazole-2
-Yl) phenol]. 2. The basic dye is 2,4-dimethyl-6-
The thermosensitive recording medium according to claim 1, which is [(4-dimethylamino) anilino] fluorane. 3. The heat-sensitive recording material according to claim 1, wherein the ultraviolet absorbent has an average particle diameter of 2 μm or less.