JPH08310132A - Thermal recording material - Google Patents

Abstract

PURPOSE: To enhance recording sensitivity, recording image quality, the preservability of a recording image and recording running properties by adding an N-arylsulfonylurea compd. represented by a specific formula and amorphous silica specified in the average particle size and oil absorbance of secondary particles to the recording layer of a thermal recording material. CONSTITUTION: In a thermal recording material wherein a recording layer is provided on a support, an N-arylsulfonylurea compd. represented by formulae I, II and amorphous silica of which the secondary particles have an average particle size of 3-10μm and oil absorbancy of 120-300ml/100g are added to the recording layer. In the formulae I, II, R1 is a 1-4C alkyl group, a 1-4C alkoxyl group, a benzyloxy group, a halogen atom or a hydroxyl group, A is a divalent, trivalent or tetravalent group, n is an integer of 2-4, m is an integer of 0-5, R2 and R3 are a 1-4C alkyl group, a 1-4C alkoxyl group, a benzyloxy group, a halogen atom or a hydroxyl group and p and q are an integer of 0-5.

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 between a colorless or light-colored basic dye and a coloring agent, which is excellent in recording sensitivity, recording image quality, recording image storability and recording running property. The present invention relates to a thermosensitive recording medium.

[0002]

2. Description of the Related Art A heat-sensitive recording material which utilizes a color reaction between a colorless or light-colored basic dye and an organic or inorganic color-forming agent to bring both color-forming substances into contact with each other by heat to obtain a recorded image is often used. Are known. Since such a thermosensitive 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.

As one of the fields of use thereof, a heat-sensitive recording material for a handy terminal, which is used for meter reading and the like, has been attracting attention. The heat-sensitive recording material for a handy terminal is required to have a quality such that a recorded image does not fade even if it comes into contact with chemicals such as fingerprints, hand cream, oil, or a plasticizer used in resins such as vinyl chloride resin. For example, a heat-sensitive recording material using an N-arylsulfonylurea compound as a coloring agent for a basic dye that is less discolored even when contacted with chemicals is described in JP-A-5-32061 and JP-A-5-143753. However, there is a problem in recording runnability due to sticking and head residue during recording.

[0004]

Further, in order to improve sticking and head residue, the oil absorption amount in the recording layer is 80 m.
A heat-sensitive recording material containing a pigment of 1/100 g or more is described in JP-A-53-86229. However, when an N-arylsulfonylurea compound is used as a color-developing agent, sticking or head residue may occur during recording. Since it occurs a little, improvement is required. An object of the present invention is to provide a thermosensitive recording medium which uses an N-arylsulfonylurea compound as a color developing agent and is excellent in recording sensitivity, recording image quality, storability of recorded images and recording runnability.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have found that in a thermosensitive recording medium having a recording layer containing a colorless or pale basic dye and a color former on a support, The N-arylsulfonylurea compound represented by the general formula (1) or the general formula (2), and the secondary particles having an average particle size of 3 to 10 μm and an oil absorption of 120 to 300 ml /
By including 100 g of amorphous silica,
The inventors have found that the above problems can be solved and completed the present invention.

[0006]

Embedded image

[Wherein R ₁ is a C ₁ -C ₄ alkyl group,
C ₁ -C ₄ alkoxyl group, benzyloxy group, halogen atom or hydroxyl group, A is divalent, trivalent or tetravalent
Valence, n shows the integer of 2-4, m shows the integer of 0-5. ]

[0008]

[Chemical 4]

[In the formula, R ₂ and R ₃ are each C _{1 to} C ₄
Represents an alkyl group, a C ₁ -C ₄ alkoxyl group, a benzyloxy group, a halogen atom or a hydroxyl group, and p and q each represent an integer of 0 to 5. ]

[0010]

The present invention provides a thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, wherein the recording layer has the following general formula (1) or The N-arylsulfonylurea compound represented by (2) and the average particle size of secondary particles measured by the Coulter counter measurement method is 3 to 10 μm, and the oil absorption (based on JIS K 5101) is 120 to 300.
ml / 100 g of specific amorphous silica (or the specific amorphous silica having a primary particle diameter of 1 to 20 nm is used), and the average particle diameter of secondary particles. Is less than 3 μm, the effect of improving sticking is low, and if it exceeds 10 μm, the recording image quality is degraded. Further, when the oil absorption amount is less than 120 ml / 100 g, head dregs are often generated, and when it exceeds 300 ml / 100 g, the recorded image is whitened and the recording density is lowered. Therefore, the range of 150 to 250 ml / 100 g is more preferable. The content of the specific amorphous silica in the recording layer is preferably 2 to 15% by weight, more preferably 3 to 10% by weight based on the total solid content of the recording layer.

In the present invention, as the colorless or light-colored basic dye contained in the recording layer, there are various known dyes, and specific examples thereof include 3,3-bis (p-dimethylaminophenyl) -6. -Dimethylaminophthalide, 3
-(4-Diethylamino-2-methylphenyl) -3-
(4-Dimethylaminophenyl) -6-dimethylaminophthalide, 3- (N-ethyl-Np-tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7-anilinofluorane , 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3- (N-ethyl-
N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7 -Anilino Fluoran, 3
-Di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino-7
-(O-chlorophenylamino) fluorane, 3- (N
-Ethyl-N-isobutyl) amino-7- (p-trifluoromethylanilino) fluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3- (N-ethyl-N-isobutyl) Amino-7-
(O-trifluoromethylanilino) fluorane, 3-
(N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-
7-anilinofluorane, 3,3-bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide , 3-p- (p-anilinoanilino) anilino-6-methyl-7-chlorofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro [ Phthalide-3,9'-xanthene-2'-ylamino] phenyl} propane,
3,6, -bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide and the like can be mentioned. Of course, it is not limited to these, and two or more kinds may be used in combination as required. The amount of the basic dye used is not particularly limited, but is preferably in the range of 3 to 20% by weight based on the total solid amount of the recording layer.

Specific examples of the N-arylsulfonylurea compound represented by the above general formula (1) or general formula (2), which is used in combination with a basic dye as a color former, include the following. 1,2-bis (p-toluenesulfonylaminocarbonylamino) ethane, 1,
1,6,6-Tetra (p-toluenesulfonylaminocarbonylamino) hexane, 1,5-bis (p-toluenesulfonylaminocarbonylamino) -3-oxapentane, 1,3-bis (p-toluenesulfonylaminocarbonyl) Amino) -2-propanone, 1,3-bis (p-toluenesulfonylaminocarbonylamino) benzene, 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane, 4,4′-bis (o-toluene) Sulfonylaminocarbonylamino)
Diphenylmethane, 4,4'-bis (benzenesulfonylaminocarbonylamino) diphenylmethane, 2,2
-Bis [4,4 '-(p-toluenesulfonylaminocarbonylamino) phenyl] propane, 1,3-bis (p-toluenesulfonylaminocarbonylaminomethyl) benzene, 1,5-bis (p-toluenesulfonylaminocarbonyl) Aminomethyl) naphthalene, 4,4 '
-Bis (p-toluenesulfonylaminocarbonylamino) diphenyl ether, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylsulfone, 4,4'-bis (p-ethylphenylsulfonylaminocarbonylamino) diphenylmethane, 4 , 4 '
-Bis (p-benzyloxyphenylsulfonylaminocarbonylamino) diphenylmethane, 4,4'-bis (p-chlorophenylsulfonylaminocarbonylamino) diphenylmethane,

N- (p-toluenesulfonyl) -N'-
Phenylurea, N- (p-toluenesulfonyl)-
N '-(p-tolyl) urea, N- (p-toluenesulfonyl) -N'-(o-tolyl) urea, N- (p-toluenesulfonyl) -N '-(m-tolyl) urea, N
-(P-toluenesulfonyl) -N '-(pn-propylphenyl) urea, N- (p-toluenesulfonyl) -N'-(pn-butylphenyl) urea, N-
(P-Toluenesulfonyl) -N '-(p-methoxyphenyl) urea, N- (p-toluenesulfonyl)-
N '-(p-ethoxyphenyl) urea, N- (p-toluenesulfonyl) -N'-(p-chlorophenyl) urea, N- (p-toluenesulfonyl) -N '-(o-
Chlorophenyl) urea, N- (p-toluenesulfonyl) -N '-(m-chlorophenyl) urea, N- (p
-Toluenesulfonyl) -N '-(2,4-dichlorophenyl) urea, N- (p-toluenesulfonyl)-
N '-(2,4,6-trimethylphenyl) urea,

N- (p-toluenesulfonyl) -N'-
(M-Hydroxyphenyl) urea, N- (p-toluenesulfonyl) -N '-(p-hydroxyphenyl) urea, N-benzenesulfonyl-N'-phenylurea, N-benzenesulfonyl-N'-(p- Trily) urea, N-benzenesulfonyl-N '-(p-methoxyphenyl) urea, N-benzenesulfonyl-N'-
(P-Hydroxyphenyl) urea, N-benzenesulfonyl-N '-(o-hydroxyphenyl) urea, N
-(P-chlorophenylsulfonyl) -N'-phenylurea, N- (o-toluenesulfonyl) -N'-phenylurea, N- (p-ethylphenylsulfonyl)-
N'-phenylurea, N- (p-methoxyphenylsulfonyl) -N'-phenylurea, N- (o-methoxyphenylsulfonyl) -N'-phenylurea, N-
(P-Ethoxyphenylsulfonyl) -N'-phenylurea, N- (p-isopropoxyphenylsulfonyl) -N'-phenylurea, N- (p-benzyloxyphenylsulfonyl) -N'-phenylurea, N-
(2,4-dimethylphenylsulfonyl) -N'-phenylurea and the like. Of course, it is not limited to these, and two or more kinds may be used in combination as required.

Among these N-arylsulfonylurea compounds, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane and N-
(P-Toluenesulfonyl) -N′-phenylurea is more preferably used because it has less background fog.

The present invention uses the N-arylsulfonylurea compound represented by the above general formula (1) or general formula (2) as a color developing agent, but other various known color developing agents may be used in combination. it can. For example, 4,4'-dihydroxy-diphenylmethane, 4,4'-isopropylidene diphenol 4,4'-cyclohexylidene bisphenol, 4,4 '-(1,3-dimethylbutylidene) bisphenol, 2,2-bis (4-hydroxyphenyl)-
4-methyl-pentane, 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-methoxydiphenyl sulfone, 4-hydroxy- 4'-isopropoxydiphenyl sulfone, 4-hydroxy-3 ', 4'-trimethylene diphenyl sulfone, 4-hydroxy-3', 4'-tetramethylene diphenyl sulfone, 3,3'-diallyl-4,4'- Dihydroxydiphenyl sulfone, 1,3
-Di [2- (4-hydroxyphenyl) -2-propyl] benzene, hydroquinone monobenzyl ether, 4
-Benzyl hydroxybenzoate, zinc 4- [2- (p-methoxyphenoxy) ethyloxy] salicylate, 4-
Examples include [3- (p-tolylsulfonyl) propyloxy] salicylate zinc and the like. As for the amount of coloring agent used,
The amount is preferably 50 to 500% by weight based on the colorless to light-colored basic dye.

In the heat-sensitive recording material of the present invention, a sensitizer can be added to the recording layer in order to increase recording sensitivity. Specific examples of the sensitizer include stearic acid amide and methoxycarbonyl-N-. Stearic acid benzamide, ethylenebistearic acid amide, methylenebisstearic acid amide, N-methylolstearic acid amide, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, shu Acid-di-p-methylbenzyl, oxalic acid-di-p-chlorobenzyl, 2-naphthylbenzyl ether, m-terphenyl, p-benzylbiphenyl, tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether, 1 , 2-di (3-methylphenoxy) ethane, 1 2-di (4-methylphenoxy)
Ethane, 1,2-di (4-methoxyphenoxy) ethane, 1,2-di (4-chlorophenoxy) ethane, 1,
2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (2-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetotoluidide, p-acetophenene Examples include thizide, N-acetoacetyl-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, but it is generally desirable to adjust the amount of the sensitizer within the range of about 400% by weight or less with respect to the basic dye.

Further, a preservative improving agent may be used in combination depending on the purpose in order to further enhance the preservability of the recorded image as long as the effects of the present invention are not impaired. Specific examples of such a storage stability improver include, for example, 2,2'-methylenebis (4-
Ethyl-6-tert-butylphenol), 2,2'-methylenebis (6-tert-butylphenol), 4,4 '
-Thiobis (5-methyl-6-tert-butylphenol), 4,4'-thiobis (2-ethyl-6-tert-butylphenol), 4,4'-butylidenebis (6-te)
rt-butyl-m-cresol), 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4)
-Hydroxy-5-tert-butylphenyl) butane,
2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,
Hindered phenol compounds such as 5-dimethylphenyl) propane, 1,4-diglycidyloxybenzene,
Epoxy compounds such as 4,4′-diglycidyloxydiphenyl sulfone, diglycidyl terephthalate, and bisphenol A type epoxy resin, 1- [α-methyl-α-
(4'-Hydroxyphenyl) ethyl] -4- [α ',
α′-bis (4 ″ -hydroxyphenyl) ethyl] benzene, N, N′-di-2-naphthyl-p-phenylenediamine, 2,2′-methylenebis (4,6-di-tert-
Butylphenyl) sodium phosphate and the like.

In order to prepare a coating liquid for a recording layer containing these compounds, water is generally used as a dispersion medium, and a basic dye, a coloring agent, and further a basic dye, a coloring agent, and the like are required by a stirrer / pulverizer such as a ball mill, attritor or sand mill. A sensitizer or the like added according to the above is dispersed together or separately to prepare a coating liquid.

In the coating solution, starch, hydroxyethyl cellulose, methyl cellulose,
Carboxymethyl cellulose, gelatin, casein, arabic gum, 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, with these inorganic pigments 10 to 40% by weight of the composite emulsion based on the total solid content of the recording layer,
Preferably about 15 to 30% by weight is used.

Various auxiliaries can be added to the coating liquid, for example, dispersion of sodium dioctylsulfosuccinate, sodium dodecylbenzene sulfonate, sodium lauryl alcohol sulfate / sodium salt, alginate, fatty acid metal salt and the like. Agents, benzophenone-based, triazole-based and other UV absorbers, other defoamers, fluorescent dyes,
Examples include coloring dyes. Further, if necessary, a lubricant such as zinc stearate or calcium stearate, an inorganic pigment such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica, and activated clay can be added. Is.

In the present invention, the method for forming the recording layer is not particularly limited, and the recording layer can be formed according to a conventionally well-known and conventional technique, for example, air knife coating, varibar blade coating, pure blade coating, rod blade coating, The recording layer coating solution is applied on the support in a dry weight of ² to 12 g / m ² , preferably 3 by a suitable coating method such as short dwell coating, curtain coating or die coating.
It is formed by a method of applying and drying about 10 to 10 g / m ² . The support may be appropriately selected from paper, plastic film, synthetic paper, non-woven fabric, metal deposit, etc., and used.

If desired, a protective layer may be provided on the recording layer and the back side of the thermosensitive recording medium to further improve the storage stability. Furthermore, the undercoat layer may be provided on the support, smoothing treatment such as super calendering may be applied after each layer is coated, or the back surface of the recording material may be treated with an adhesive to form an adhesive label. Various publicly known techniques can be added as needed.

[0024]

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. Unless otherwise specified, "part" and "%" in the examples mean "part by weight" and "% by weight", respectively.

Example 1 Preparation of Solution A 30 parts of 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 5% aqueous solution of methylcellulose 1
A composition consisting of 0 part and 60 parts of water was pulverized with a sand mill until the average particle size became 0.8 μm or less.

Preparation of Solution B A composition comprising 30 parts of 1,2-di (3-methylphenoxy) ethane, 10 parts of a 5% aqueous solution of methylcellulose, and 60 parts of water has a mean particle size of 1.2 μm or less in a sand mill. Crushed until.

Preparation of Solution C 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane 20 parts, N- (p-toluenesulfonyl) -N′-phenylurea 10 parts, 5% aqueous solution of methylcellulose 10 parts, A composition comprising 60 parts of water and water was pulverized with a sand mill until the average particle size became 2 μm or less.

Formation of recording layer 50 parts of liquid A, 100 parts of liquid B, 100 parts of liquid C, 80 parts of 10% aqueous solution of polyvinyl alcohol, and amorphous silica (average particle diameter of secondary particles 5.4 μm, oil absorption 200 ml)
/ 100g) 5 parts, calcium carbonate 1 part, aluminum hydroxide 15 parts, zinc stearate emulsion (30% liquid) 5
Parts are mixed and stirred, and the resulting coating liquid is applied on one side of a high-quality paper of 60 g / m ² so that the coating amount after drying is 6 g / m ² to form a recording layer, and a super calender A thermal recording material was obtained by processing.

[Example 2] 4, 4'in liquid C preparation
-Bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane 20 parts and N- (p-toluenesulfonyl) -N'-phenylurea 10 parts instead of 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 30 parts were used.

Example 3 In the preparation of solution C, 4, 4 '
-Bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane 20 parts and N- (p-toluenesulfonyl) -N'-phenylurea 10 parts instead of 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane 10 parts and N-
(P-Toluenesulfonyl) -N′-phenylurea 2
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 0 part was used.

Example 4 In the formation of the recording layer of Example 1, amorphous silica (average particle size of secondary particles: 5.4 μm) was used.
m, oil absorption 200 ml / 100 g) 5 parts instead of amorphous silica (average particle size of secondary particles 3.5 μm, oil absorption 2
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 5 parts (00 ml / 100 g) was used.

Example 5 In the formation of the recording layer of Example 1, amorphous silica (average particle size of secondary particles: 5.4 μm) was used.
m, oil absorption 200 ml / 100 g) 5 parts instead of amorphous silica (secondary particles having an average particle size of 7.6 μm, oil absorption 1
Example 1 except that 10 parts of 50 ml / 100 g) were used.
A thermosensitive recording medium was obtained in the same manner as described above.

Comparative Example 1 In the formation of the recording layer of Example 1, amorphous silica (secondary particles having an average particle size of 5.4 μm) was used.
m, oil absorption amount 200 ml / 100 g) A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 25 parts of a rocoidal silica dispersion having a primary particle diameter of 20 nm (solid concentration 20%) was used instead of 5 parts. .

Comparative Example 2 Amorphous silica of Example 1 (average particle size of secondary particles: 5.4 μm, oil absorption: 200 ml / 1)
00g) is amorphous silica (average particle size of secondary particles is 1.5
μm, oil absorption 250 ml / 100 g)
A thermal recording material was obtained in the same manner as in Example 1.

Comparative Example 3 Amorphous silica of Example 1 (average particle size of secondary particles: 5.4 μm, oil absorption: 200 ml / 1)
00 g) as amorphous silica (average particle size of secondary particles: 3.6
μm, oil absorption 100 ml / 100 g)
A thermal recording material was obtained in the same manner as in Example 1.

Comparative Example 4 Amorphous silica of Example 1 (average particle size of secondary particles: 5.4 μm, oil absorption: 200 ml / 1)
Amorphous silica (average particle size of secondary particles 12μ
m, oil absorption 150 ml / 100 g) except that the thermal recording material was obtained in the same manner as in Example 1.

[Comparative Example 5] In the preparation of solution C, 4, 4 '
20 parts of bis (p-toluenesulfonylaminocarbonyl) and N- (p-toluenesulfonyl) -N '
4-hydroxy-4 'instead of 10 parts phenylurea
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that 30 parts of isopropoxydiphenyl sulfone was used.

The thermal recording material thus obtained was subjected to the following quality evaluation tests, and the results are shown in Table 1. [Evaluation] [Color density] The color density of the recorded image obtained by recording with a thermal recording evaluation machine (TH-PMD type, manufactured by Okura Electric Co., Ltd., applied energy 0.4 mJ / dot) was measured by a Macbeth densitometer (manufactured by Macbeth Co., RD-91
4R type) was measured in visual mode.

[Head meal] After recording for 30 m with a thermal recording evaluation machine (TH-PMD type, Okura Electric Co., Ltd., applied energy 0.4 mJ / dot), the degree of head meal was visually judged. Evaluation Criteria A: There is almost no head residue. ◯: The head meal adheres slightly. X: There are many head meals.

[Sticking] Recording was performed with a thermosensitive recording evaluation device (TH-PMD type, manufactured by Okura Electric Co., applied energy 0.3 mJ / dot, pulse width 3 ms), and recording sound was judged. Evaluation Criteria ◯: There is no recorded sound. Δ: Recording sound is slightly audible ×: Recording sound is large.

[Recording Image Quality] Recording was performed with a thermal recording evaluation machine (TH-PMD type, manufactured by Okura Electric Co., applied energy 0.3 mJ / dot, pulse width 3 ms), and the image quality of the obtained recorded image was visually judged. Evaluation Criteria ⊚: The recording image quality is very excellent. ◯: The recording image quality is excellent. ×: Inferior recording quality [Preservation of recorded image] Wrap film (trade name: KMA-W, manufactured by Mitsui Toatsu Kagaku Co., Ltd.) containing a plasticizer was wrapped around a polycarbonate pipe (40 mmφ pipe) in three layers The thermosensitive recording medium recorded at the time of measuring the above-mentioned color density was placed on the film, and a wrap film was further wound around it in three layers and allowed to stand at 40 ° C. for 24 hours, and then the color density was measured by a Macbeth densitometer (manufactured by Macbeth Co.,
RD-914R type) in visual mode.

[0042]

[Table 1]

[0043]

As is clear from the results shown in Table 1, the thermosensitive recording medium of the present invention has a recording sensitivity, a recording image quality, a storability of a recorded image,
The heat-sensitive recording material was excellent in recording runnability.

Claims (3)

[Claims] 1. A thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, wherein the recording layer contains the following general formula (1) or general formula (2). )
And an amorphous silica having an average particle diameter of secondary particles of 3 to 10 μm and an oil absorption of 120 to 300 ml / 100 g. . Embedded image [In the formula, R ₁ represents a C _{1 to} C ₄ alkyl group, a C _{1 to} C ₄ alkoxyl group, a benzyloxy group, a halogen atom or a hydroxyl group, A is divalent, trivalent or tetravalent, and n is Two
Is an integer of 4 and m is an integer of 0-5. ] [Chemical 2] [Wherein R ₂ and R ₃ are each a C _{1 to} C ₄ alkyl group, a C _{1 to} C ₄ alkoxyl group, a benzyloxy group,
Indicates a halogen atom or hydroxyl group, and p and q are 0
Represents an integer of from 5 to 5. ] 2. The N-arylsulfonylurea compound is 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane or N- (p-toluenesulfonyl) -N′-phenylurea.
The heat-sensitive recording material described. 3. The heat-sensitive recording material according to claim 1, wherein the amorphous silica is contained in an amount of 2 to 15% by weight based on the total solid content of the recording layer.