JPH08276665A - Thermosensible recording body - Google Patents

Abstract

PURPOSE: To improve an optical character reading property in a region of a specific wave length by making phthaladinone represented by the formula and black coloring fluoran represented by the formula contained in the recording layer as a basic dye so as to be a specific wt.%. CONSTITUTION: This thermosensible recording body contains 5-100wt.% phthaladinone compound represented by the formula I with respect to a black coloring fluoran compound represented by the formula II in the recording layer as a basis dye. Under these conditions, even when left in a high temerature and humidity environments and exposed in light for a long period of time, the property in an optical character reading operation undergoes no deterioration in a region of the wave length of 650-700nm. In the formula I, R1 -R4 respectively is a 1-6C alkyl group R5 is a hydrogen atom or a 1-6C alkyl group, R6 , R7 are each a hydrogen atom, a 1-6C alkyl group or alkoxy group, and A and B are each a carbon or nitrogen group. In the formula II, R8 , R9 respectively is 1-6C alkyl group, an ethoxypropyl group, R10 is a hydrogen atom or a methyl group, and R11 is a methyl group, chlorine atom, or trifluoromethyl group. Further, (n) is an integer of 0-2.

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 color developing agent, and particularly, it is suitable for optical character reading (OCR) in the wavelength region of 650 to 700 nm. The present invention relates to an excellent thermal recording material.

[0002]

2. Description of the Related Art A thermosensitive recording medium is known in which a color or color reaction between a colorless or pale basic dye and an organic or inorganic coloring agent is used to bring a color image into contact with each other to obtain a recorded image. Has been. Since such a thermal recording material is relatively inexpensive and the recording device is compact and its repair is relatively easy, it is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields.

With the recent diversification of needs, various performances are required for the thermal recording material. As one of them, there is a demand for a thermal recording material for OCR or OMR which has a black color tone and is readable in the wavelength region of 650 to 700 nm. As a method for obtaining such a heat-sensitive recording material, the coating amount of the black-coloring fluoran dye which has been conventionally used is simply increased, or 65 is applied at the time of coloring.
Examples of the dye having a strong absorption at 0 to 700 nm include 3,3-bis (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide or 3-di-n-butylamino-6,8,8-trimethyl-8. , 9-dihydro-
A method is used in which (3,2, e) pyridofluorane or the like is used in combination with a black coloring fluorane dye. However, although these methods have the OCR suitability immediately after color development, the OCR suitability is lost when the composition is left under high temperature and high humidity or exposed to light for a long time. Therefore, improvement thereof is strongly demanded.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a thermal recording material having excellent suitability for optical character reading (OCR) in the wavelength region of 650 to 700 nm.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have proposed a thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a color developing agent. As the dye, at least one phthalazinone compound represented by the following general formula (1) and at least one black coloring fluoran compound represented by the following general formula (2) are used, and the phthalazinone compound is 5-100 of the fluoran compound. weight%
It has been found that the above problem can be solved by containing such a substance as described below, and the present invention has been completed.

[0006]

[Chemical 4]

[Wherein R₁~ R_FourAre each C₁~ C₆
The alkyl group or benzyl group of R _FiveIs a hydrogen atom
Is C₁~ C₆The alkyl group of R₆, R₇Each is water
Elementary atom, C₁~ C₆Alkyl group or C₁~ C₆A
Indicates a lucoxy group. A and B are carbon atoms or nitrogen atoms
However, at least one is a nitrogen atom. ]

[0008]

Embedded image

[In the formula, R ₈ and R ₉ are each C _{1 to} C ₆
Is an alkyl group, an ethoxypropyl group or a p-tolyl group, R ₁₀ is a hydrogen atom or a methyl group, and R ₁₁ is a methyl group, a chlorine atom or a trifluoromethyl group. n shows the integer of 0-2. ]

[0010]

In the heat-sensitive recording material of the present invention, as a basic dye, a specific phthalazinone compound is contained in an amount of 5 to 100% by weight, preferably 10 to 5% by weight, based on the specific black coloring fluoran compound.
When used in an amount of 0% by weight, it is 650 to 70 even when left under high temperature and high humidity or exposed to light for a long time.
Optical character reading in the wavelength region of 0 nm (OC
R) It is possible to obtain a black color-developing heat-sensitive recording material which does not deteriorate in suitability.

When the amount of the basic dye in the recording layer is increased, the readability for optical characters is naturally improved, but the basic dye is taken into consideration in view of recording sensitivity, yellowing of unrecorded paper upon light exposure, and economy. The amount is preferably adjusted in the range of 0.2 to 1.0 g / m ² . If the amount of the phthalazine compound in the recording layer is less than 5% by weight with respect to the fluoran compound, the OCR suitability is lost, especially after long-term exposure to light, and if it exceeds 100% by weight, a black color appears. A colored image cannot be obtained and the OCR suitability immediately after coloring is also reduced.

The phthalazinone compound represented by the above general formula (1) used in the present invention is a dye having a green or blue color tone when used alone, and specific examples thereof include the following compounds. . 4,4-bis (4-dimethylaminophenyl) -5-aza-3,4-
Dihydrophthalazin-1-one, 4,4-bis (4-dimethylaminophenyl) -8-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-dimethylaminophenyl)- 5,8-diaza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-diethylaminophenyl) -5-aza-3,4-dihydrophthalazin-1-one, 4,4- Bis (4-diethylaminophenyl) -8-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-diethylaminophenyl)-
5,8-Diaza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-di-n-butylaminophenyl) -5-aza-3,4-dihydrophthalazin-1-one , 4,4-bis (4-di-n-butylaminophenyl) -8-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-di-n-butylaminophenyl) -5,8-Diaza-3,4-dihydrophthalazine-
1-one, 4,4-bis (4-N-methyl-N-n-propylaminophenyl) -5-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-N -Methyl-N-n-propylaminophenyl) -8-aza-3,
4-dihydrophthalazin-1-one, 4,4-bis (4
-N-methyl-N-n-propylaminophenyl)-
5,8-Diaza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-N-ethyl-N-isoamylaminophenyl) -5-aza-3,4-dihydrophthalazine-1 -On,

4,4-bis (4-N-ethyl-N-isoamylaminophenyl) -8-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-N-ethyl- N-isoamylaminophenyl) -5,8-diaza-
3,4-dihydrophthalazin-1-one, 4- (4-dimethylaminophenyl) -4- (4-diethylaminophenyl) -5-aza-3,4-dihydrophthalazine-1
-One, 4- (4-dimethylaminophenyl) -4-
(4-Diethylaminophenyl) -5,8-diaza-
3,4-Dihydrophthalazin-1-one, 4,4-bis (4-dimethylaminophenyl) -5-aza-2-methyl-3,4-dihydrophthalazin-1-one, 4,4-
Bis (4-dimethylaminophenyl) -5,8-diaza-2-methyl-3,4-dihydrophthalazin-1-one, 4,4-bis (4-diethylaminophenyl) -5
-Aza-2-methyl-3,4-dihydrophthalazine-1
-One, 4,4-bis (4-diethylaminophenyl)
-5,8-Diaza-2-methyl-3,4-dihydrophthalazin-1-one, 4,4-bis (4-dimethylaminophenyl) -5-aza-2-ethyl-3,4-dihydrophthal Razin-1-one, 4,4-bis (4-dimethylaminophenyl) -5,8-diaza-2-ethyl-3,4
-Dihydrophthalazin-1-one, 4,4-bis (4-
Diethylaminophenyl) -5-aza-2-ethyl-
3,4-dihydrophthalazin-1-one, 4,4-bis (4-diethylaminophenyl) -5,8-diaza-2
-Ethyl-3,4-dihydrophthalazin-1-one,
4,4-bis (4-dimethylamino-2-methylphenyl) -5-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-dimethylamino-2-methylphenyl)- 8-aza-3,4-dihydrophthalazine-1
-On,

4,4-bis (4-dimethylamino-2-)
Methylphenyl) -5,8-diaza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-diethylamino-2-methylphenyl) -5-aza-3,4-dihydrophthalazine- 1-one, 4,4-bis (4-diethylamino-2-methylphenyl) -8-aza-3,4-
Dihydrophthalazin-1-one, 4,4-bis (4-diethylamino-2-methylphenyl) -5,8-diaza-3,4-dihydrophthalazin-1-one, 4,4-bis (4- Di-n-butylamino-2-methylphenyl)
-5-aza-3,4-dihydrophthalazin-1-one,
4,4-bis (4-di-n-butylamino-2-methylphenyl) -8-aza-3,4-dihydrophthalazine-
1-one, 4,4-bis (4-di-n-butylamino-)
2-Methylphenyl) -5,8-diaza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-diethylamino-2-ethylphenyl) -5-aza-3,4-
Dihydrophthalazin-1-one, 4,4-bis (4-diethylamino-2-ethylphenyl) -8-aza-3,
4-dihydrophthalazin-1-one, 4,4-bis (4
-Diethylamino-2-ethylphenyl) -5,8-diaza-3,4-dihydrophthalazin-1-one, 4,4
-Bis (4-diethylamino-2-methoxyphenyl)
-5-aza-3,4-dihydrophthalazin-1-one,
4,4-bis (4-diethylamino-2-methoxyphenyl) -8-aza-3,4-dihydrophthalazine-1-
On, 4,4-bis (4-diethylamino-2-methoxyphenyl) -5,8-diaza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-dimethylamino-2-ethoxy) Phenyl) -5-aza-3,4-dihydrophthalazin-1-one,

4,4-bis (4-dimethylamino-2-)
Ethoxyphenyl) -8-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-dimethylamino-2-ethoxyphenyl) -5,8-diaza-3,4-
Dihydrophthalazin-1-one, 4,4-bis (4-diethylamino-2-ethoxyphenyl) -5-aza-
3,4-dihydrophthalazin-1-one, 4,4-bis (4-diethylamino-2-ethoxyphenyl) -8-
Aza-3,4-dihydrophthalazin-1-one, 4,4
-Bis (4-diethylamino-2-ethoxyphenyl)
-5,8-Diaza-3,4-dihydrophthalazine-1-
On, 4,4-bis (4-di-n-butylamino-2-
Ethoxyphenyl) -5-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-di-n-butylamino-2-ethoxyphenyl) -8-aza-3,4-
Dihydrophthalazin-1-one, 4,4-bis (4-di-n-butylamino-2-ethoxyphenyl) -5,8
-Diaza-3,4-dihydrophthalazin-1-one,
4,4-bis (4-diethylamino-2-isopropoxyphenyl) -5-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-diethylamino-2-)
Isopropoxyphenyl) -8-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-diethylamino-2-isopropoxyphenyl) -5,8-diaza-3,4-dihydrophthal Radin-1-one, 4,4-
Bis (4-diethylamino-2-n-hexyloxyphenyl) -5-aza-3,4-dihydrophthalazine-1
-One, 4,4-bis (4-diethylamino-2-n-
Hexyloxyphenyl) -8-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-diethylamino-2-n-hexyloxyphenyl) -5,8-
Diaza-3,4-dihydrophthalazin-1-one,

4,4-bis (4-diethylamino-2-)
Ethoxyphenyl) -5-aza-2-methyl-3,4-
Dihydrophthalazin-1-one, 4,4-bis (4-diethylamino-2-ethoxyphenyl) -8-aza-2
-Methyl-3,4-dihydrophthalazin-1-one,
4,4-bis (4-diethylamino-2-ethoxyphenyl) -5,8-diaza-2-methyl-3,4-dihydrophthalazin-1-one, 4,4-bis (4-diethylamino-2-) Ethoxyphenyl) -5-aza-2-ethyl-3,4-dihydrophthalazin-1-one, 4,4-
Bis (4-diethylamino-2-ethoxyphenyl)-
8-aza-2-ethyl-3,4-dihydrophthalazine-
1-one, 4,4-bis (4-diethylamino-2-ethoxyphenyl) -5,8-diaza-2-ethyl-3,
4-dihydrophthalazin-1-one, 4,4-bis (4
-Diethylamino-2-ethoxyphenyl) -5-aza-2-n-butyl-3,4-dihydrophthalazine-1-
On, 4,4-bis (4-diethylamino-2-ethoxyphenyl) -5-aza-2-n-hexyl-3,4-
Dihydrophthalazin-1-one, 4,4-bis (4-dibenzylaminophenyl) -5-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-dibenzylaminophenyl) ) -8-Aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-dibenzylaminophenyl) -5,8-diaza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-dibenzylamino-2-ethoxyphenyl) -5-aza-3,4-dihydrophthalazin-1-one, 4,4-bis (4-dibenzylamino-2-ethoxyphenyl) ) -8-aza-3,
4-dihydrophthalazin-1-one,

4,4-bis (4-dibenzylamino-2)
-Ethoxyphenyl) -5,8-diaza-3,4-dihydrophthalazin-1-one, 4- (4-dimethylaminophenyl) -4- (4-diethylamino-2-methylphenyl) -5-aza- 3,4-dihydrophthalazine-1
-One, 4- (4-dimethylaminophenyl) -4-
(4-Diethylamino-2-methylphenyl) -8-aza-3,4-dihydrophthalazin-1-one, 4- (4
-Dimethylaminophenyl) -4- (4-diethylamino-2-methylphenyl) -5,8-diaza-3,4-
Dihydrophthalazin-1-one, 4- (4-dimethylaminophenyl) -4- (4-diethylamino-2-ethoxyphenyl) -5-aza-3,4-dihydrophthalazin-1-one, 4- ( 4-dimethylaminophenyl)-
4- (4-diethylamino-2-ethoxyphenyl)-
8-aza-3,4-dihydrophthalazin-1-one, 4
-(4-Dimethylaminophenyl) -4- (4-diethylamino-2-ethoxyphenyl) -5,8-diaza-
3,4-dihydrophthalazin-1-one and the like. Of course, it is not limited to these, and two or more kinds may be used in combination as required.

In the present invention, specific examples of the black coloring fluoran compound represented by the general formula (2) include the followings. 3-diethylamino-6-methyl-7-anilinofluorane, 3-di-n-butylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (m-toluidino) Fluoran, 3-di-n-butylamino-6-methyl-7-
(M-toluidino) fluorane, 3-diethylamino-
6-methyl-7- (2,4-xylidino) fluorane,
3-diethylamino-6-methyl-7- (3,5-xylidino) fluorane, 3-diethylamino-6-methyl-7- (2,6-xylidino) fluorane, 3-di-n
-Butylamino-6-methyl-7- (2,4-xylidino) fluorane, 3-di-n-butylamino-6-methyl-7- (3,5-xylidino) fluorane, 3-di-
n-Butylamino-6-methyl-7- (2,6-xylidino) fluorane, 3-dimethylamino-6-methyl-
7-anilinofluorane, 3-di-n-propylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) -6-
Methyl-7- (p-toluidino) fluorane, 3-di-
n-Pentylamino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-propylamino) -6-
Methyl-7-anilinofluorane, 3- (N-ethyl-
N-isopentylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-Nn-hexylamino) -6-methyl-7-anilinofluorane, 3- (N
-Ethyl-N-isobutylamino) -6-methyl-7-
Anilinofluorane, 3-diethylamino-7- (o-
Chloroanilino) fluorane, 3-di-n-butylamino-7- (o-chloroanilino) fluorane, 3- (N
-Ethyl-N-n-hexylamino) -7- (o-chloroanilino) fluorane, 3- (N-ethyl-N-isopentylamino) -7- (o-chloroanilino) fluorane, 3-di-n-butyl Amino-7- (o-fluoroanilino) fluorane, 3-di-n-butylamino-6
-Methyl-7- (p-chloroanilino) fluorane, 3
-Diethylamino-7- (m-trifluoromethylanilino) fluorane, 3-di-n-butylamino-7-
(M-trifluoromethylanilino) fluorane, 3-
Diethylamino-6-methyl-7- (p-trifluoromethylanilino) fluorane, 3- (N-ethyl-N-
Ethoxypropyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-ethoxypropyl) amino-6-methyl-7-anilinofluorane and the like.
Among these, 3-di-n-butylamino-6-methyl-7-anilinofluorane is particularly preferably used because it exhibits excellent properties in terms of color developability and background fog. In the present invention, other known dyes may be used in combination as long as the desired effects are not impaired.

The colorant used in the present invention is not particularly limited, and various known compounds can be used, but a diphenyl sulfone derivative represented by the following general formula (3) is particularly selected. When used for a long time, it exerts a particularly excellent effect on OCR suitability after long-term storage, and is therefore preferably used.

[0020]

[Chemical 6]

[In the formula, R ₁₂ and R ₁₃ are each C _{1 to} C ₄
Alkyl group, an alkenyl group of C ₂ -C ₄ of, C ₁ -C ₄
Represents an alkoxyl group, a benzyloxy group or a halogen atom. r is an integer of 0 to 2, s is an integer of 1 to 3, t,
u shows the integer of 0-2, respectively. ]

Examples of the diphenyl sulfone derivative represented by the general formula (3) include the following compounds.
4,4'-dihydroxydiphenyl sulfone, 2,4 '
-Dihydroxydiphenyl sulfone, 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone, 3,
3 ', 5,5'-tetrabromo-4,4'-dihydroxydiphenyl sulfone, 3,3', 5,5'-tetrachloro-4,4'-dihydroxydiphenyl sulfone, 4
-Hydroxydiphenylsulfone, 4-hydroxy-
4'-methyldiphenyl sulfone, 4-hydroxy-
3 ', 4'-tetramethylene diphenyl sulfone, 4-
Hydroxy-4'-methoxydiphenyl sulfone, 4-
Hydroxy-4'-ethoxydiphenyl sulfone, 4-
Hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-n-butoxydiphenyl sulfone, 4-hydroxy-4'-benzyloxydiphenyl sulfone, 3,4-dihydroxydiphenyl sulfone, 3,4-dihydroxy-4. '-Methyldiphenyl sulfone, 3,4,4'-trihydroxydiphenyl sulfone, 3,4,3', 4'-tetrahydroxydiphenyl sulfone, 2,3,4-trihydroxydiphenyl sulfone 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 coloring agents, 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone,
2,4'-dihydroxydiphenyl sulfone and 4-
Hydroxy-4′-isopropoxydiphenyl sulfone is particularly preferably used because it exhibits particularly excellent performance in recording sensitivity and OCR suitability after long-term storage as well as background fog.

The ratio of the basic dye to the color former used in the recording layer is not particularly limited, but generally 100 to 1000 parts by weight, preferably 200 to 100 parts by weight of the dye.
500 parts by weight of color former are used.

In the heat-sensitive recording material of the present invention, various heat-fusible substances can be used as a recording sensitivity improver in the recording layer. Examples of such a heat-fusible substance include the following compounds. Caproic acid amide, capric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, erucic acid amide, linoleic acid amide, linolenic acid amide, N-methylstearic acid amide, stearic acid anilide, N-methyloleic acid amide, Benzanilide, linoleic acid anilide, N-ethylcapric acid amide, N-butyllauric acid amide, N-
Octadecylacetamide, N-oleinacetamide, N-oleylbenzamide, N-stearylcyclohexylamide, 1-benzyloxynaphthalene, 2-
Benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester, 1,2-diphenoxyethane, 1,
4-diphenoxybutane, 1,2-bis (3-methylphenoxy) ethane, 1,2-bis (4-methoxyphenoxy) ethane, 1-phenoxy-2- (4-chlorophenoxy) ethane, 1-phenoxy- 2- (4-methoxyphenoxy) ethane, 1- (2-methylphenoxy)-
2- (4-methoxyphenoxy) ethane, terephthalic acid dibenzyl ester, oxalic acid dibenzyl ester, oxalic acid di (4-methylbenzyl) ester, oxalic acid di (4-chlorobenzyl) ester, p-benzyloxybenzoic acid Benzyl ester, p-benzylbiphenyl,
1,5-bis (p-methoxyphenoxy) -3-oxa-pentane, 1,4-bis (2-vinyloxyethoxy) benzene, p-biphenyl-p-tolyl ether,
Benzyl-p-methylthiophenyl ether, 2-
(2'-hydroxy-5'-methylphenyl) benzotriazole, 2-hydroxy-4-benzyloxybenzophenone and the like.

The amount of the recording storage improver used is not particularly limited, but is generally 50 to 1000 parts by weight, preferably 10 parts by weight with respect to 100 parts by weight of the basic dye.
It is preferably used in the range of 0 to 500 parts by weight.

The recording layer may contain various known storability improvers in order to further improve the storability. Specific examples of the storage stability improver include the following compounds. 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-tert-butylphenol), 4,4'-butylidenebis (6-tert-butyl-m-cresol), 4-benzyloxyphenyl-
4 '-(2-methyl-2,3-epoxypropyloxy) phenyl sulfone, 1,3,5-trimethyl-2,
4,6-Tris (4,5-di-tert-butyl-4-
(Hydroxybenzyl) benzene, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, p-octylphenyl salicylate, 2- (2'-hydroxy-
5'-methylphenyl) benzotriazole, ethyl-
2-cyano-3,3'-diphenyl acrylate, tetra (2,2,6,6-tetramethyl-4-piperidyl)
-1,2,3,4-butane tetracarboate, 2,
Sodium salt or magnesium salt of 2'-methylenebis (4,6-di-tert-butylphenyl) phosphoric acid and the like. The coating liquid containing these is generally prepared by using water as a dispersion medium, and a dye, a color former, a heat-fusible substance, etc. together or separately by a stirring and crushing machine such as a ball mill, an attritor, a sand mill and a colloid mill. It is prepared by dispersing.

In such a coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, styrene / maleic anhydride copolymer salt, styrene / acrylic acid copolymer are usually used as binders. Combined salt, styrene-butadiene copolymer emulsion, etc. are 10 to 40% by weight of the total solid content, preferably 15 to 3%.
About 5% by weight is used.

Further, various auxiliary agents can be added to the coating liquid, for example, dispersants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate / sodium salt, and fatty acid metal salt. UV absorbers such as triazoles, antifoaming agents, fluorescent dyes, coloring dyes, and antioxidants. In order to prevent sticking of the thermosensitive recording medium due to contact with recording equipment or recording head, use a dispersion or emulsion of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, etc. in the paint. It can also be added. In addition, inorganic pigments such as kaolin, clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, fine anhydrous silica, and activated clay can be added to improve the adhesion of scum to the recording head.

The support may be paper (including neutral paper), plastic film, synthetic paper, or plastic film or synthetic paper laminated with coated paper or high-quality paper via an adhesive, or paper. A laminate of plastic is used. Specific examples of the plastic film include films of polyethylene, polyester, polypropylene, polyvinyl chloride, polystyrene, nylon and the like. Also, as synthetic paper,
For example, a synthetic paper produced by a film method or a fiber method is used. In the film method, a synthetic resin, a filler, and an additive are melt-kneaded and then extruded to form a film. There is a surface coating method, a surface treatment method, and the like, and the fiber synthetic paper includes synthetic pulp paper and spunbond paper.

The method of applying the recording layer is not particularly limited, and it can be formed according to a conventionally well-known and commonly used technique, for example, bar coating, air knife coating, rod blade coating, pure blade coating, short dwell coating. And the like. When a plastic film is used as the support, the coating efficiency can be increased by subjecting the surface to treatments such as corona discharge and electron beam irradiation. The coating amount of the coating liquid is also not particularly limited, but it is usually ^{2 to} 10 g / m ² , preferably 3 to 7 g in dry weight.
It is adjusted in the range of about / m ² .

Further, by providing a protective layer composed of an adhesive, a lubricant, a pigment and the like on the thermosensitive recording layer, a thermosensitive recording material having excellent chemical resistance against plasticizers, oils and the like can be obtained. Specific examples of the adhesive used in the protective layer include polyvinyl alcohols having various degrees of saponification, acetoacetyl group-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, acrylic resin, and polyurethane resin. Further, it is desirable that these adhesives are adjusted in the range of 10 to 95% by weight, preferably 30 to 90% by weight, based on the total solid content. The coating amount of the protective layer is 0.5 to 10 by dry weight.
It is adjusted in the range of g / m ² , preferably in the range of ¹ to 7 g / m ² .

In addition, a layer containing a water-soluble, water-dispersible, electron beam curable or ultraviolet curable resin may be provided on the protective layer for the purpose of imparting high gloss, or the back surface of the support may be protected. Various known techniques in the field of producing a thermal recording medium can be added, such as providing a layer, providing an undercoat layer on the support, and further subjecting the back surface of the support to an adhesive treatment.

[0034]

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, "parts" and "%" in the examples mean "parts by weight" and "% by weight", respectively.

Example 1 [Preparation of solution A] 3-di-n-butylamino-6-methyl-
7-anilinofluorane 10 parts, 5 of methylcellulose
% Aqueous solution 3 parts and water 27 parts were pulverized with a sand mill until the average particle size was 0.8 μm, to obtain a liquid A.

[Preparation of solution B] 4,4-bis (4-diethylamino-2-ethoxyphenyl) -5-aza-3,4-
A composition consisting of 10 parts of dihydrophthalazin-1-one, 3 parts of a 5% aqueous solution of methylcellulose, and 27 parts of water was ground in a sand mill until the average particle size became 0.8 μm,
Liquid B was obtained.

[Preparation of Solution C] 3,3′-diallyl-4,
A composition consisting of 20 parts of 4'-dihydroxydiphenyl sulfone, 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 was 1.2 μm, and a liquid C was obtained.

[Preparation of Solution D] A composition comprising 25 parts of 1,2-bis (3-methylphenoxy) ethane, 7 parts of a 5% aqueous solution of methylcellulose, and 48 parts of water was sand-milled to an average particle size of 1.2 μm. Was pulverized to obtain a liquid D.

[Formation of Recording Layer] Liquid A 32 parts, liquid B 8 parts,
Liquid C 80 parts, liquid D 80 parts, light calcium carbonate 10 parts,
50 g / m ^{2 of} a coating liquid obtained by mixing and stirring 20 parts of fine particle silicon oxide pigment (oil absorption 180 ml / 100 g), 15 parts of a 30% dispersion of zinc stearate, and 100 parts of a 15% aqueous solution of polyvinyl alcohol. 4g dry weight on high quality paper
After coating and drying so as to be / m ² , a super calender treatment was carried out to obtain a thermosensitive recording medium.

Examples 2 to 9 In the preparation of solution B, the following compounds were used instead of 4,4-bis (4-diethylamino-2-ethoxyphenyl) -5-aza-3,4-dihydrophthalazin-1-one. A thermosensitive recording medium was obtained in the same manner as in Example 1 except that was used. Example 2: 4,4-bis (4-dimethylamino-2-
Methoxyphenyl) -5-aza-3,4-dihydrophthalazin-1-one Example 3: 4,4-bis (4-diethylamino-2-)
Methylphenyl) -5-aza-3,4-dihydrophthalazin-1-one

Example 4: 4,4-bis (4-diethylamino-2-ethoxyphenyl) -4- (4-diethylamino-2-methylphenyl) -5,8-diaza-3,
4-Dihydrophthalazin-1-one Example 5: 4,4-bis (4-diethylamino-2-)
Methylphenyl) -5,8-diaza-3,4-dihydrophthalazin-1-one

Example 6: 4,4-bis (4-dimethylaminophenyl) -5-aza-3,4-dihydrophthalazin-1-one Example 7: 4,4-bis (4-di-n) -Butylaminophenyl) -5-aza-3,4-dihydrophthalazine-
1-on

Example 8: 4- (4-Dimethylaminophenyl) -4- (4-diethylamino-2-ethoxyphenyl) -5,8-aza-3,4-dihydrophthalazin-1-one Example 9 : 4,4-bis (4-diethylamino-2-
Ethoxyphenyl) -5-aza-2-methyl-3,4-
Dihydrophthalazine-1-one

Examples 10 to 12 A thermosensitive recording medium was prepared in the same manner as in Example 1 except that the following compounds were used in place of 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone in the preparation of liquid C. Got Example 10: 2,4'-dihydroxydiphenyl sulfone Example 11: 4-hydroxy-4'-isopropoxydiphenyl sulfone Example 12: 4,4'-isopropylidenediphenol

Example 13 In preparation of solution A, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane was used in place of 3-di-n-butylamino-6-methyl-7-anilinofluorane. A thermal recording material was obtained in the same manner as in Example 1 except that the thermal recording material was used.

Comparative Example 1 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that in the formation of the recording layer, A liquid of 32 parts and B liquid of 8 parts were used in place of A liquid of 40 parts.

Comparative Examples 2 to 3 In the preparation of solution B, the following compound was used instead of 4,4-bis (4-diethylamino-2-ethoxyphenyl) -5-aza-3,4-dihydrophthalazin-1-one. A thermosensitive recording medium was obtained in the same manner as in Example 1 except that was used. Comparative Example 2: 3,3-bis (4-diethylamino-2-)
Ethoxyphenyl) -4-azaphthalide Comparative Example 3: 3-di-n-butylamino-6,8,8-
Trimethyl-8,9-dihydro- (3,2, e) pyridfluorane

The heat-sensitive recording material thus obtained was evaluated by the following methods, and the results are shown in Table 1. [PCS value] The PCS value is an index indicating the degree of readability of OCR. The PCS value represents the relative density difference between the recorded portion and the unrecorded portion, and is calculated by the following equation. _{PCS = (R W -R P)} / R W R W represents the reflectivity of the unrecorded portion, R _P represents the reflectivity of the recording unit. Therefore, the higher the PCS value, the clearer the discrimination between the recorded portion and the unrecorded portion, and the higher the readability. Generally, a PCS value of 0.7 or more is required.

[Measurement of PCS value at 670 nm] Recording was carried out with a thermal recording evaluation machine [TM-PMD type, manufactured by Okura Electric Co., Ltd., applied voltage 16 V, pulse cycle 0.51 ms, applied pulse width 0.3 ms] and recorded. The reflectance of the unrecorded area at a wavelength of 670 nm was measured with a spectrophotometer [U-3300, manufactured by Hitachi, Ltd.], and the PCS value was calculated from the value. The color tones of the obtained recorded images were all black.

[Moisture resistance] After recording, after leaving for 72 hours at 50 ° C. and 90% RH, the PCS value was calculated in the same manner.

[Light resistance] After recording, after exposure to direct sunlight for 15 hours, the PCS value was calculated in the same manner.

[0052]

[Table 1]

[0053]

As is clear from the results shown in Table 1, the thermosensitive recording medium of the present invention had a sufficiently high PCS value at 670 nm even when exposed to high temperature and high humidity or light.

Claims (2)

[Claims] 1. A colorless or light-colored basic dye on a support.
Of a thermosensitive recording medium provided with a recording layer containing a colorant and a coloring agent
In the recording layer, a basic dye represented by the following general formula (1)
At least one of the phthalazinone compounds represented and one of the following
A small amount of black fluoran compound represented by general formula (2)
At least one phthalazinone compound is a fluoran compound
The content of 5 to 100% by weight
Thermosensitive recording material to be collected. [Chemical 1][In the formula, R₁~ R_FourAre each C₁~ C₆Alkyl group of
Or a benzyl group, R _FiveIs a hydrogen atom or C₁~ C₆
The alkyl group of R₆, R₇Are hydrogen atom and C respectively₁
~ C₆Alkyl group or C₁~ C₆The alkoxy group of
Show. A and B are carbon atoms or nitrogen atoms, but few
One is a nitrogen atom. ] [Chemical 2][In the formula, R₈, R₉Are each C₁~ C₆The alkyl
Group, ethoxypropyl group or p-tolyl group, R_TenIs
A hydrogen atom or a methyl group,₁₁Is a methyl group, chlorine atom
Alternatively, it represents a trifluoromethyl group. n is an integer from 0 to 2
Is shown. ] 2. The heat-sensitive recording material according to claim 1, wherein the color former is a diphenyl sulfone derivative represented by the following general formula (3). Embedded image [In the formula, R ₁₂ and R ₁₃ each represent a C _{1 to} C ₄ alkyl group, a C _{2 to} C ₄ alkenyl group, a C _{1 to} C ₄ alkoxyl group, a benzyloxy group or a halogen atom.
r is an integer of 0 to 2, s is an integer of 1 to 3, t and u are integers of 0 to 2, respectively. ]