JP2001162951A - Multicolor heat sensitive recording body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multicolor heat sensitive recording body, by which a recorded image having a high recording density and a clear color tone is obtained and, at the same time, which has a clear color separability under high temperature atmosphere and a preservability of high temperature color developed image. SOLUTION: A high temperature color developing layer including a dye precursor and an organic developer, which develops color through the reaction with the dye precursor under heat, and a low temperature color developing layer, which develops color, the color tone of which is different from that of the high temperature color developing layer and which develops color at a temperature, which is lower than the temperature, at which color develops in the high temperature color developing layer, are provided in the order named on a support. Further, the organic developer in the high temperature color developing layer includes a diphenylsulfone cross-linking type compound represented by general formula, wherein X and Y represent 1 to 12C hydrocarbon groups, which may well be different from each other and may well be straight-chained or branched-chained groups, R1 to R6 represent halogen atoms, 1 to 6C alkyl groups and alkenyl groups, m, n, p, q, r and t represent integers from 0 through 4 and a represents an integer from 0 through 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor heat-sensitive recording material, and more particularly to a multicolor heat-sensitive recording material having a plurality of color-forming layers that develop different colors depending on the heating conditions from a thermal head. is there.

[0002]

2. Description of the Related Art In general, a heat-sensitive recording layer mainly comprising a colorless or light-colored electron-donating dye precursor (hereinafter referred to as a dye precursor) and a developer which reacts with the dye precursor when heated to form a color is provided. The heat-sensitive recording medium has
No. pp. 139, and widely used. In order to perform recording on this thermosensitive recording medium, a thermal printer or the like having a built-in thermal head is used.However, such a thermosensitive recording method has less noise at the time of recording as compared with other recording methods that have been practically used conventionally. With no development and fixing, maintenance-free, relatively inexpensive and compact equipment, and very clear color development, the facsimile and computer fields Widely used for various measuring instruments and labels. The quality required for the heat-sensitive recording medium has been diversified with the expansion of its use, and examples thereof include high sensitivity, image stabilization, and multicolor recording images. In particular, multi-color recording images have the advantage that characters or graphics to be emphasized can be clearly displayed because they can be recorded in a color tone different from other portions.

As a multicolor heat-sensitive recording material, for example, it is known that a plurality of color-forming layers, each of which develops a different color tone, are provided on a support, and a recording image is formed by utilizing a difference in heating temperature or heat energy. Oil. These have a configuration in which a high-temperature coloring layer and a low-temperature coloring layer that develops a color at a lower temperature or thermal energy than the high-temperature coloring layer are sequentially laminated,
It can be broadly divided into two methods, a decoloring type and an adding color type.

[0004] The color development mechanism in the decolorable type thermosensitive recording medium is described in, for example, Japanese Patent Publication No. 50-17865 and Japanese Patent Publication No. 57-14.
As disclosed in JP-A-320-320 and JP-A-2-80287, only the low-temperature coloring layer develops color by heating at low temperature, and has a decoloring effect on the coloring system of the low-temperature coloring layer upon heating at high temperature. The decoloring agent acts and only the high-temperature coloring layer develops color. This method has an advantage that the color tone can be freely selected, but it is necessary to add a large amount of the decoloring agent in order to obtain a sufficient decoloring effect on the low-temperature coloring layer. Such a large amount of the decoloring agent causes problems such as a decrease in the preservability of the recorded image and a reduction in the recording sensitivity because a large amount of heat energy is consumed for melting the decoloring agent.

On the other hand, examples of a color-added thermal recording medium are disclosed in JP-B-49-27708 and JP-B-51-19989.
And JP-A-51-146239 disclose a method of stacking two color-forming layers that develop colors with different colors and applying different amounts of heat to obtain distinguishable two-color images. In these methods, the upper low-temperature coloring layer develops color by heating at low temperature, and the lower high-temperature coloring layer also develops color by heating at high temperature to form both upper and lower coloring layers. In order to obtain the following, it was essential that the lower layer be substantially black. In addition, since the lower black image is obtained by mixing colors with the upper color developing system, the color of the upper color developing layer is slightly overlaid on the black image, and the difference between the two color tones is unclear, or on the dashboard of the car. When exposed to such a high-temperature atmosphere, there is a problem that the high-temperature coloring layer develops a color and the low-temperature coloring tone becomes fogged or becomes black. Also, Japanese Patent Application Laid-Open No. 4-3
Japanese Patent No. 29186 describes that a specific coloring agent is contained in a high-temperature coloring layer to solve the problem that the high-temperature coloring layer develops color at the time of low-temperature heating to cause color turbidity. The clarity of the low-temperature color tone and the stability of the ground color were still insufficient. More recently, thermal recording paper has often been used for receipts, etc., in which case it is necessary to preserve the recorded image.However, it has not yet been obtained that has sufficient image preservation. It is the current situation.

[0006]

Therefore, according to the present invention, clear color-formed images can be obtained in the low-temperature color-forming layer and the high-temperature color-forming layer, respectively, and the low-temperature color-formed image is fogged (color mixture) even in a high-temperature atmosphere by the color tone of the high-temperature color-forming layer. An object of the present invention is to provide a multicolor heat-sensitive recording medium which is excellent in color separation property without any trouble and excellent in image storability.

[0007]

According to the present invention, in order to achieve the above object, the present invention comprises, on a support, a dye precursor and an organic developer which reacts with the dye precursor under heating to form a color. A high-temperature coloring layer, and a low-temperature coloring layer that exhibits a color tone different from that of the high-temperature coloring layer and that develops a color at a temperature lower than the temperature at which the high-temperature coloring layer develops. A multicolor heat-sensitive recording material characterized by containing a diphenylsulfone cross-linkable compound represented by the following general formula (1).

[0008]

Embedded image [In the formula, X and Y each represent a hydrocarbon group which may be different from each other and may have a linear or branched saturated or unsaturated carbon atom having 1 to 12 carbon atoms, or may have an ether bond. Or

Embedded image Or

Embedded image (R represents a methylene group or an ethylene group, T represents a hydrogen atom or a C ₁ -C ₄ alkyl group). R _{1 to} R ₆ are each independently a halogen atom, a C _{1 to} C ₆ alkyl group,
Shows an alkenyl group. Also, m, n, p, q, r, and t are 0
Represents an integer of up to 4, and when it is 2 or more, R _{1 to} R ₆ may be different from each other. a represents an integer of 0 to 10. ]

Further, according to the present invention, the low-temperature coloring layer which exhibits a color tone different from that of the high-temperature coloring layer and which develops at a temperature lower than the temperature at which the high-temperature coloring layer develops is not limited to a single layer. No, coloring layer that develops color at lower temperature,
By sequentially laminating the color images, it is possible to obtain a color image having a plurality of color tones.

A multicolor heat-sensitive recording medium that develops a color tone of two or more colors is much more susceptible to a change in temperature environment than an ordinary heat-sensitive recording medium because of its color-forming mechanism utilizing a difference in heating temperature or heat energy. It can be said that. In the case of a low-temperature color tone formed by low-temperature heating (low-energy printing), it is important to minimize the influence of color development of the high-temperature color-forming layer in order to maintain the sharpness of the color tone. To do this,
It is considered effective to increase the melting point of the color developer used in the high-temperature coloring layer to suppress the coloring of a part of the high-temperature coloring layer during heating at a low temperature.

However, even if a developer having a high melting point is simply used, when the high-temperature coloring layer and the low-temperature coloring layer are laminated, mixing occurs between the two layers and the melting point is lowered. As compared with the case where the layers are separately provided on a support, the ground color stability against heat is remarkably deteriorated and the whiteness is reduced. For example, when 2,4'-dihydroxydiphenylsulfone or 4,4'-dihydroxydiphenylsulfone, which is conventionally known as a developer having a relatively high melting point, is used, the color development at an environment of about 60.degree. And the ground color stability is not sufficient.

On the other hand, the present inventors have found that by containing the diphenylsulfone cross-linkable compound represented by the general formula (1) in the high-temperature coloring layer, ground coloring in a high-temperature environment is prevented and low-temperature coloring is achieved. The present inventors have found that fogging of an image by a high-temperature coloring layer can be improved and that the storage stability of a high-temperature coloring image is significantly improved, and the present invention has been completed. Although the reason why the excellent action and effect are obtained in the present invention is not clear, the diphenylsulfone cross-linked compound represented by the general formula (1) is specifically capable of responding to heat as compared with a general phenol-based developer. Because of high stability,
Since the fogging by the high-temperature coloring layer on the low-temperature coloring image is small, and it does not develop color even when placed in a high-temperature environment,
It is considered that the color tone of the low-temperature coloring image can be kept clear.

When the diphenylsulfone cross-linkable compound represented by the general formula (1) is used, the stability of the recorded image to solvents such as oil and plasticizer is very high as compared with a general phenol type developer. Although the reason is not clear, the bond with the leuco dye is strong due to the presence of a plurality of sulfone groups in the molecule, or a kind of complex formed when reacted with the leuco dye is soluble in these solvents. Is low.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the multicolor thermosensitive recording medium of the present invention, the color tone of each color forming layer is adjusted by selecting a leuco dye as a dye precursor. In the case of a two-color thermosensitive recording medium, for example, the low-temperature coloring layer is a single-color system (for example, blue, red, yellow, etc.) having a single absorption peak when coloring, and the high-temperature coloring layer is different. It is preferable to use a multicolor system (for example, green, black, etc.) having a plurality of absorption peaks when the color is developed in a mixed color tone because a clear color tone can be easily obtained and the color separation property is good.

When a black leuco dye is used in the high-temperature coloring layer of the present invention, among others, 3-diethylamino-7- (o
-Chloroanilino) fluoran, 3-diethylamino-
6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran,
3-di-n-pentylamino-6-methyl-7-anilinofluoran, 3- (N-ethyl-p-toluidino)
-6-Methyl-7-anilinofluoran and 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran are 3-{[(phenylamino) When used in combination with [carbonyl] amino} benzenesulfonamide, it is preferable because it does not develop color at the time of heating at low temperature, does not cause fogging to the low-temperature coloring image, and can obtain an extremely clear black color image even at the time of heating at high temperature. . Further, among these, 3-diethylamino-7
-(O-chloroanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino) fluoran, and 3
-(N-ethyl-p-toluidino) -6-methyl-7
-The use of anilinofluorane is particularly preferred, since a thermosensitive recording material having very little ground color when stored under high-temperature conditions can be obtained.

In addition to the above, as the leuco dye used in the heat-sensitive recording medium of the present invention, any of those known in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used, and there is no particular limitation. Preferred are a triphenylmethane-based compound, a fluoran-based compound, a fluorene-based compound, a divinyl-based compound, and the like. Specific examples of typical basic colorless dyes 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) fluorane 3-diethylamino-6-methyl-7-chlorofluoran 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-diethylamino-6-methyl-7- (m- Methylanilino) fluoran 3-diethylamino-6-meth Le-7- (o-chloroanilino) fluoran 3-diethylamino-6-methyl-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-methylanilino Fluoran 3-diethylamino-6-ethoxyethyl-7-anilinov Oran 3-diethylamino-7-methylfluorane 3-diethylamino-7-dibenzylaminofluoran 3-diethylamino-6,8-dimethylfluoran 3-diethylamino-7-chlorofluorane 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-anilinofluoran 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-dibutylamino-6-methyl-7- (o-fluoroanilino ) Fluorane 3-dibutylamino-6-methyl-7- (m-trifluoromethylanilino) fluoran 3-Dibutylamino-6-methyl-chlorofluorane 3-Dibutylamino-6-methyl-7-bromofluoran 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-fluoroani Rino) fluorane 3-di-n-pentylamino-6-methyl-7-anilinofluoran 3-di-n-pentylamino-6-methyl-7- (p-
Chloroanilino) fluorane 3-di-n-pentylamino-7- (m-trifluoromethylanilino) fluoran 3-di-n-pentylamino-6-chloro-7-anilinofluoran 3-di-n-pentyl Amino-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- (Np-tolyl-N-ethylamino) -7- (N-phenylmethyl-N-methyl) fluoran 3- (N-ethyl-N-ethoxypropylamino) -6
-Methyl-7-anilinofluoran 3-N-ethyl-N-isoamylamino-benzo [a]
Fluoran 3-N-ethyl-Np-methylphenylamino-7-
Methylfluoran 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 2,4-dimethyl- 6-[(4-dimethylamino) anilino] -fluoran

<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 3,3-bis (1-n-butyl-2-methylindol-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 present invention, at least one of the diphenylsulfone cross-linkable compounds represented by the general formula (1) is used as a color developer contained in the high-temperature coloring layer. The diphenylsulfone bridged compound of the general formula (1) is described in JP-A-10-29969.

In the general formula (1), the groups represented by X and Y are as follows. Methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group, methylmethylene group, dimethylmethylene Group, methylethylene group, methyleneethylene group, ethylethylene group, 1,2-
Dimethylethylene group, 1-methyltrimethylene group, 1-
Methyltetramethylene group, 1,3-dimethyltrimethylene group, 1-ethyl-4-methyl-tetramethylene group, vinylene group, propenylene group, 2-butenylene group, ethynylene group, 2-butynylene group, 1-vinylethylene group , Ethyleneoxyethylene group, tetramethyleneoxytetramethylene group, ethyleneoxyethyleneoxyethylene group, ethyleneoxymethyleneoxyethylene group, 1,3
-Dioxane-5,5-bismethylene group, 1,2-xylyl group, 1,3-xylyl group, 1,4-xylyl group, 2
-Hydroxytrimethylene group, 2-hydroxy-2-methyltrimethylene group, 2-hydroxy-2-ethyltrimethylene group, 2-hydroxy-2-propyltrimethylene group, 2-hydroxy-2-isopropyltrimethylene group, A 2-hydroxy-2-butyltrimethylene group and the like.

The alkyl group or alkenyl group of R ₁ to R ₆ is a C _{1 to} C ₆ alkyl group or a C _{1 to} C ₆ alkenyl group, and specific examples include a methyl group and an ethyl group. , N-propyl group, isopropyl group, n-butyl group,
sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, n-hexyl group, isohexyl group, 1-methylpentyl group, 2-methylpentyl group, vinyl group Allyl group, isopropenyl group, 1-propenyl group, 2-butenyl group, 3-butenyl group, 1,3-butanedienyl group, 2
-Methyl-2-propenyl group and the like. Examples of the halogen atom include chlorine, bromine, fluorine and iodine.

In the present invention, the diphenylsulfone cross-linked compound represented by the general formula (1) may have a substituent and / or a
Can be used in combination, and the content ratio thereof is arbitrary. Also, the method of mixing,
There is no particular limitation on the method of mixing powders, mixing in the state of a dispersion dispersed in water or the like, and simultaneously producing and containing a plurality of types of diphenylsulfone cross-linked compounds depending on production conditions.

In the case of using a mixture of several kinds of diphenylsulfone cross-linked compounds represented by the general formula (1), a particularly preferred composition is a compound represented by the general formula (4):
Contains two or more kinds that differ only in the value of. With such a compound, the production method is also simple, and compounds having different values of a can be synthesized at once with an arbitrary content ratio by changing the reaction ratio of the raw materials.

[0026]

Embedded image (Wherein, X, Y, R1, m and a are the same as described above)

The compound represented by the general formula (1) includes
Specific examples are as follows. (1-1) 4,4'-bis [4- [4- (4-hydroxyphenylsulfonyl) phenoxy] -2-trans-
Butenyloxy] diphenylsulfone (1-2) 4,4'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy-4-butyloxy] diphenylsulfone (1-3) 4,4'-bis [4- (4- (Hydroxyphenylsulfonyl) phenoxy-3-propyloxy] diphenylsulfone (1-4) 4,4'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy-2-ethyloxy] diphenylsulfone (1-5) 4- [ 4- (4-hydroxyphenylsulfonyl) phenoxy-4-butyloxy] -4 '-[4-
(4-hydroxyphenylsulfonyl) phenoxy-
3-propyloxy] diphenylsulfone (1-6) 4- [4- (4-hydroxyphenylsulfonyl) phenoxy-4-butyloxy] -4 '-[4-
(4-hydroxyphenylsulfonyl) phenoxy-
2-ethyloxy] diphenylsulfone (1-7) 4- [4- (4-hydroxyphenylsulfonyl) phenoxy-3-propyloxy] -4 '-[4
-(4-hydroxyphenylsulfonyl) phenoxy-2-ethyloxy] diphenylsulfone (1-8) 4,4'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy-5-pentyloxy] diphenylsulfone (1-9 ) 4,4'-Bis [4- (4-hydroxyphenylsulfonyl) phenoxy-6-hexyloxy] diphenylsulfone (1-10) 4- [4- [4- (4-hydroxyphenylsulfonyl) phenoxy] -2 -Trans-butenyloxy] -4 '-[4- (4-hydroxyphenylsulfonyl) phenoxy-4-butyloxy] diphenylsulfone (1-11) 4- [4- (4-hydroxyphenylsulfonyl) phenoxy-2-trans- Butenyloxy)
-4 '-[4- (4-hydroxyphenylsulfonyl)
Phenoxy-3-propyloxy] diphenylsulfone (1-12) 4- [4- [4- (4-hydroxyphenylsulfonyl) phenoxy] -2-trans-butenyloxy] -4 '-[4- (4-hydroxyphenyl Sulfonyl) phenoxy-2-ethyloxy] diphenylsulfone

(1-13) 1,4-bis [4- [4-
[4- (4-hydroxyphenylsulfonyl) phenoxy-2-trans-butenyloxy] phenylsulfonyl] phenoxy] -cis-2-butene (1-14) 1,4-bis [4- [4- [4- (4 -Hydroxyphenylsulfonyl) phenoxy-2-trans-butenyloxy] phenylsulfonyl] phenoxy] -trans-2-butene (1-15) 4,4'-bis [4- [4- (2-hydroxyphenylsulfonyl) phenoxy] Butyloxy)
Diphenyl sulfone (1-16) 4,4'-bis [4- [2- (4-hydroxyphenylsulfonyl) phenoxy] butyloxy]
Diphenylsulfone (1-17) 4,4'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy-2-ethyleneoxyethoxy] diphenylsulfone (1-18) 4,4'-bis [4- (4- (Hydroxyphenylsulfonyl) phenyl-1,4-phenylenebismethyleneoxy] diphenylsulfone (1-19) 4,4'-bis [4- (4-hydroxyphenylsulfonyl) phenyl-1,3-phenylenebismethyleneoxy] diphenyl Sulfone (1-20) 4,4'-bis [4- (4-hydroxyphenylsulfonyl) phenyl-1,2-phenylenebismethyleneoxy] diphenylsulfone (1-21) 2,2'-bis [4- [ 4- [4- (4-
(Hydroxyphenylsulfonyl) phenoxy-2-ethyleneoxyethoxy] phenylsulfonyl] phenoxy] diethyl ether (1-22) α, α'-bis [4- [4- [4- (4-
(Hydroxyphenylsulfonyl) phenyl-1,4-phenylenebismethyleneoxy] phenylsulfonyl] phenoxy] -p-xylene (1-23) α, α'-bis [4- [4- [4- (4-
(Hydroxyphenylsulfonyl) phenyl-1,3-phenylenebismethyleneoxy] phenylsulfonyl] phenoxy] -m-xylene (1-24) α, α'-bis [4- [4- [4- (4-
(Hydroxyphenylsulfonyl) phenyl-1,2-phenylenebismethyleneoxy] phenylsulfonyl] phenoxy] -o-xylene

(1-25) 2,4'-bis [2- (4-
(Hydroxyphenylsulfonyl) phenoxy-2-ethyleneoxyethoxy] diphenylsulfone (1-26) 2,4'-bis [4- (2-hydroxyphenylsulfonyl) phenoxy-2-ethyleneoxyethoxy] diphenylsulfone (1-27) 4,4'-bis [3,5-dimethyl-4
-(3,5-Dimethyl-4-hydroxyphenylsulfonyl) phenoxy-2-ethyleneoxyethoxy] diphenylsulfone (1-28) 4,4'-bis [3-allyl-4- (3-
Allyl-4-hydroxyphenylsulfonyl) phenoxy-2-ethyleneoxyethoxy] diphenylsulfone (1-29) 4,4'-bis [3,5-dimethyl-4-
(3,5-dimethyl-4-hydroxyphenylsulfonyl) phenyl-1,4-phenylenebismethyleneoxy] diphenylsulfone (1-30) 4,4'-bis [3,5-dimethyl-4-
(3,5-dimethyl-4-hydroxyphenylsulfonyl) phenyl-1,3-phenylenebismethyleneoxy] diphenylsulfone (1-31) 4,4'-bis [3,5-dimethyl-4-
(3,5-dimethyl-4-hydroxyphenylsulfonyl) phenyl-1,2-phenylenebismethyleneoxy] diphenylsulfone (1-32) 4,4'-bis [3-allyl-4- (3-
Allyl-4-hydroxyphenylsulfonyl) 1,4-
Phenylenebismethyleneoxy] diphenylsulfone (1-33) 4,4'-bis [3-allyl-4- (3-
Allyl-4-hydroxyphenylsulfonyl) 1,3-
Phenylenebismethyleneoxy] diphenylsulfone (1-34) 4,4'-bis [3-allyl-4- (3-
Allyl-4-hydroxyphenylsulfonyl) 1,2-
Phenylenebismethyleneoxy] diphenylsulfone (1-35) 4,4'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy-2-hydroxypropyloxy] diphenylsulfone (1-36) 1,3-bis [4 -[4- [4- (4-hydroxyphenylsulfonyl) phenoxy-2-hydroxypropyloxy] phenylsulfonyl] phenoxy] -2-hydroxypropane

Among the compounds represented by the general formula (4) used in the present invention, particularly those having a = 0 are described in JP-A-7-14.
No. 9713, International Publication WO93 / 06074, WO95
/ 33714, and typically, 1,3-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] -2-hydroxypropane 1,1-bis [4- (4-hydroxyphenyl) Sulfonyl) phenoxy] methane 1,2-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] ethane 1,3-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] propane 1,4-bis [4- ( 4-hydroxyphenylsulfonyl) phenoxy] butane 1,5-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] pentane 1,6-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] hexane α, α'- Bis [4- (4-hydroxyphenylsulfonyl) phenoxy] -p-xylene α, '-Bis [4- (4-hydroxyphenylsulfonyl) phenoxy] -m-xylene α, α'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] -o-xylene 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether 4,4'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] dibutyl ether 1,2-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] ethylene 1 , 4-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] -2-butene.

The compound represented by the general formula (1) can be obtained by converting a 4,4'-dihydroxydiphenylsulfone derivative or a 2,4'-dihydroxydiphenylsulfone derivative to a basic substance according to the method described in International Publication WO / 16420. It is obtained by reacting below. The color developer used in the present invention contains one or two or more kinds of diphenylsulfone cross-linked compounds synthesized by the above-mentioned means. Among them, a composition obtained by the following synthesis example is preferable.

Synthesis Example 1 16.0 g (0.4 mol) of sodium hydroxide was added to 21.2 g of water, and after dissolution, 4,4'-dihydroxydiphenyl sulfone (hereinafter referred to as BPS) was added.
50.0 g (0.2 mol) was added. Then 1
At 05 ° C, bis (2-chloroethyl) ether 1
4.3 g (0.10 mol) was added, and 110 ° C. to 115 ° C.
For 5 hours. After the reaction is completed, add 375 of water to the reaction solution.
Then, the mixture was stirred at 90 ° C. for 1 hour. After cooling to room temperature, the mixture was neutralized with 20% sulfuric acid, and the precipitated crystals were separated by filtration.
9.3 g were obtained. The yield from bis (2-chloroethyl) ether was 88%. The composition was as follows by high performance liquid chromatography. However, the column is Mi
gtysil RP-18 (manufactured by Kanto Kagaku), and the mobile phase is CH ₃ CN: H ₂ O: 1% H ₃ PO ₄ = 700: 300:
5. The UV wavelength is 260 nm.

[0033]

Embedded image a = 0; retention time: 1.9 minutes, area%: 32.9 a = 1; retention time: 2.3 minutes, area%: 21.7 a = 2; retention time: 2.7 minutes, area% : 12.8 a = 3; retention time: 3.4 minutes, area%: 8.8 a = 4; retention time: 4.2 minutes, area%: 5.8 a = 5; retention time: 5.4 Min, area%: 3.5 a = 6; retention time: 7.0 minutes, area%: 2.2 a = 7; retention time: 9.0 minutes, area%: 1.7 a = 8; retention time : 11.8 min, area%: 1.3 a = 9; retention time: 15.4 min, area%: 1.3

(Synthesis Examples 2 to 4) Assuming that the molar ratio of BPS and bis (2-chloroethyl) ether reacted in Synthesis Example 1 is 1.5: 1.0, 2.5: 1.0, 3.0: 1.0, the following composition is obtained. Could be obtained. When 1.5: 1.0, a = 0; Area%: 20.8, a = 1; Same: 33.0, a = 2; Same: 14.2, a = 3; Same: 7.9, a = 4 The same: 3.9 2.5: 1.0, a = 0; the same: 49.6, a = 1; the same: 25.9, a = 2; the same: 11.4, a = 3; the same: 5. 3, a = 4; same as 2.4 3.0: 1.0, a = 0; same as 56.9, a = 1; same as 24.9, a = 2; same as 9.6, a = 3 The same: 3.7, a = 4; the same: 1.3

Synthesis Example 5 10.0 g of 48% aqueous sodium hydroxide solution and N, N'-dimethylacetamide
In 155 g of the mixed solution, 30.0 g of BPS (0.1
2 mol) was added. After melting at 80 ° C, xylene 1
Α, α'-dichloro-p-xylene dissolved in 5 g
10.5 g (0.06 mol) was slowly added dropwise. After completion of the dropwise addition, a thermal aging reaction was performed at the same temperature for 2 hours. After aging,
The crystals were poured into 900 ml of water and the precipitated crystals were separated by filtration.
The crude crystals were washed with methanol, filtered and dried to obtain 19.7 g of white crystals. When the purity was measured by high performance liquid chromatography, the main composition was as follows. α, α'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] -p-xylene 59.1% 4,4'-bis [4- (4-hydroxyphenylsulfonyl) phenyl-1,4-phenylenebis Methyleneoxy] diphenylsulfone 23.1% α, α'-bis [4- [4- [4- (4-hydroxyphenylsulfonyl) phenyl-1,4-phenylenebismethyleneoxy] phenylsulfonyl] phenoxy]-
p-xylene 11.1%

In the present invention, examples of the color developer contained in the low-temperature coloring layer include, for example, JP-A-3-207688,
Bisphenol A, 4-hydroxybenzoic acid ester, 4-hydroxyphthalic acid diester, phthalic acid monoester described in JP-A-5-24366, etc.
Bis- (hydroxyphenyl) sulfides, 4-hydroxyphenylarylsulfones, 4-hydroxyphenylarylsulfonates, 1,3-di [2- (hydroxyphenyl) -2-propyl] -benzenes,
-Hydroxybenzoyloxybenzoic acid esters, bisphenolsulfones, aminobenzenesulfonamide derivatives described in JP-A-8-59603, International Publication WO97
/ 16420 is exemplified. These developers are appropriately selected depending on desired recording sensitivity and other characteristics. Specific examples of typical known color developers are shown below, but the present invention is not particularly limited thereto.

<Bisphenol A>4,4'-isopropylidenediphenol (also known as bisphenol A) 4,4'-cyclohexylidenediphenol 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 <Diesters of 4-hydroxyphthalic acid> 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 phthalate Monoethyl 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'-n-propoxydiphenylsulfone4-hydroxy-4'-n-butyloxydiphenylsulfone<4-hydroxyphenylarylsulfonates> 4-hydroxyphenylbenzenesulfonate 4-hydroxyphenyl-p-tolylsulfonate 4-hydroxyphenylmethylenesulfonate 4-hydroxyphenyl-p-chlorobenzenesulfonate 4-hydroxyphenyl- p-tert-butylbenzenesulfonate 4-hydroxyphenyl-p-isopropoxybenzenesulfonate 4-hydroxyphenyl-1'-naphthalenesulfonate 4-hydroxy Cyphenyl-2'-naphthalene sulfonate

<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 Roxybenzoyloxy nonyl 4-hydroxybenzoyloxybenzoate cyclohexyl 4-hydroxybenzoyloxybenzoate β-phenethyl 4-hydroxybenzoyloxybenzoate phenyl 4-hydroxybenzoyloxybenzoate α-naphthyl 4-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'-sulfonyldiphenol3,3'-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 4,4′-bis (p-tolylsulfonylaminocarbonylamino) diphenylmethane 4,4′- Bis (phenylaminothioca Boniruamino) diphenyl sulfide

In addition to the above, metal chelate-type coloring components such as higher fatty acid metal double salts and polyvalent hydroxy aromatic compounds described in JP-A-10-258577 can also be used as image forming materials. These chelate coloring components are used alone or in combination with the above-mentioned leuco dye and developer.

In the present invention, the recording sensitivity can be adjusted by adding a conventionally known sensitizer to each color-forming layer as long as the desired effect on the above-mentioned object is not impaired. Examples of such a sensitizer include stearic acid amide, palmitic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoylstearic acid amide, N-eicosanoic acid amide, ethylenebisstearic acid amide, behenic acid amide, and methylenebis Stearamide, methylolamide, N-methylol stearamide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, dibenzyl oxalate, oxalic acid -Di-p-methylbenzyl, oxalic acid-di-p-chlorobenzyl, 2-naphthylbenzyl ether, m-terphenyl, p-benzylbiphenyl, 4-biphenylparatolyl ether, di (p-methoxypheno) 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-
Acetophenetizide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane, 1,2-bis (phenoxy Methyl) benzene, p-toluenesulfonamide,
Examples thereof include o-toluenesulfonamide, di-p-tolyl carbonate, and phenyl-α-naphthyl carbonate, but are not particularly limited thereto. These sensitizers may be used alone or in combination of two or more.

As the binder used in 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, butyral-modified polyvinyl alcohol Modified polyvinyl alcohol such as alcohol, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, cellulose derivatives such as acetyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer, polyvinyl chloride, polyvinyl acetate, polyacrylamide , Polyacrylate, polyvinyl butyral, polystyrene and copolymers thereof, polyamide resin, silicone Butter, petroleum resins, terpene resins, ketone resins, and coumarone resins. These polymeric substances include water, alcohol, ketones, esters,
In addition to being used by dissolving in a solvent such as a hydrocarbon, it can be used in a state of being emulsified or dispersed in water or another medium in the form of a paste, and used in combination depending on required quality.

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

In order to more clearly obtain the color tone of the high-temperature coloring layer, it is effective to reduce the amount of the filler in the high-temperature coloring layer or not to mix it. This is because, in the case of an additive type, a color forming composition (a reaction product of a leuco dye and a color developer, that is, a color image) formed in a high-temperature color-forming layer during high-temperature heating is not limited to a high-temperature color-forming layer. This is presumably because the mixture is easily absorbed by the filler in the layer and is efficiently mixed with the low-temperature coloring composition to obtain a high-temperature coloring tone that is a mixed color.

In addition, releasing agents such as fatty acid metal salts, lubricants such as waxes, benzophenone-based and triazole-based ultraviolet absorbers, waterproofing agents such as glyoxal, dispersants, defoamers, antioxidants, fluorescent Dyes and the like can be used.

As the support, paper, recycled paper, synthetic paper, plastic film, foamed plastic film, nonwoven fabric, metal foil and the like can be used, or a composite sheet combining these can be used.

Further, for the purpose of enhancing the abrasion resistance, an overcoat layer of a polymer substance or the like can be provided on the thermosensitive coloring layer. Further, for the purpose of increasing the color-forming sensitivity, an undercoat layer containing an organic filler or an inorganic filler can be provided between the color-forming layer and the support.

The amounts of the color developer and leuco dye and the types and amounts of other various components in each color forming layer of the multicolor thermosensitive recording material of the present invention are determined according to the required performance and recording suitability, and are particularly limited. However, usually, 0 to 4 parts of a filler and 1 to 2 parts of a binder are contained in the total solid content with respect to 1 part of a developer.
5% is appropriate. The leuco dye is preferably contained in an amount of 0.1 to 2 parts with respect to 1 part of the developer.

When a leuco dye which develops a multicolor system is used as the high-temperature coloring layer and the color tone of the high-temperature coloring layer (multicolor coloring) is obtained by heating at a high temperature, the dye 1 in the low-temperature coloring layer may be used.
It is effective that the amount of the dye in the high-temperature coloring layer is 1 to 3 parts, preferably about 1.5 to 2.8 parts per part. When a dye that develops a monochromatic color is used as the high-temperature coloring layer and the low-temperature coloring layer, and the color tone at the time of high-temperature heating is a multicolor coloring, the ratio of each monochromatic dye in the high-temperature coloring layer and the low-temperature coloring layer is as follows. , Can be arbitrarily adjusted according to a desired color tone.

In the present invention, the coating amount of each color-forming layer is not particularly limited, but is generally 1.5 to 1 in terms of dry weight.
It is adjusted within a range of about 2 g / m ² . Further, in the present invention, an intermediate layer can be provided between the high-temperature coloring layer and the low-temperature coloring layer. The binder, filler, sensitizer, defoamer, ultraviolet absorber, fluorescent dye, and the like described above can be appropriately blended into the coating liquid for forming the intermediate layer. Further, the coating amount of the intermediate layer may be adjusted in a range of about 1 to 10 g / m ² .

These developers, dyes and materials to be added as required are pulverized by a pulverizer such as a ball mill, an attritor, a sand grinder or an appropriate emulsifier to a particle diameter of several microns or less, and a binder and Various coating materials are added according to the purpose to form a coating liquid. Examples of the coating method include hand coating, size press coater method, roll coater method, air knife coater method, blend coater method, flow coater method, comma direct method, gravure direct method, gravure reverse method, reverse roll coater method and the like. . After spraying, spraying or dipping, drying may be performed.

[0054]

EXAMPLES <Manufacture of thermosensitive recording medium> The thermosensitive recording medium of the present invention will be described below by way of examples. In addition, parts and% in the description
Represents parts by weight and% by weight, respectively, unless otherwise specified. Example 1 Example 1 relates to a two-color heat-sensitive recording material, and in a low-temperature color-forming layer, 4-hydroxy-4'-isopropoxydiphenylsulfone as a color developer and 3,3-bis (p-dimethylamino) as a leuco dye. Phenyl) -6-dimethylaminophthalide (blue-colored leuco dye), compound (1-1) as a color developer and 3-dibutyl-7- (o-chloroanilino) fluoran (black-colored) as a leuco dye in a high-temperature color-forming layer. (Leuco dye).

A developer dispersion (liquid) for a low-temperature coloring layer having the following composition and a leuco dye dispersion (blue)
Liquid), and a developer dispersion (liquid) for a high-temperature color-forming layer and a leuco dye dispersion (liquid) that develops a black color are separately wet-ground with a sand grinder until the average particle diameter is 1 micron. went. Liquid (developer dispersion liquid) 4-hydroxy-4'-isopropoxydiphenyl sulfone 6.0 parts 10% polyvinyl alcohol 18.8 parts Water 11.2 parts Liquid (blue leuco dye dispersion) 3,3-bis (P-dimethylaminophenyl) -6-dimethylaminophthalic 1.0 part 10% polyvinyl alcohol 2.3 parts water 1.3 parts Liquid (developer dispersion liquid) Compound (1-1) 6.0 parts 10% polyvinyl Alcohol 18.8 parts Water 11.2 parts Liquid (black leuco dye dispersion) 3-dibutyl-7- (o-chloroanilino) fluoran 1.0 part 10% polyvinyl alcohol 2.3 parts Water 1.3 parts Then Was mixed and stirred to prepare a dispersion. [Preparation of low-temperature coloring layer coating liquid] Liquid (developer dispersion liquid) 36.0 parts Liquid (blue leuco dye dispersion liquid) 13.8 parts Silicon oxide pigment (25% dispersion liquid; Mizukasil P-527 (Mizusawa Chemical) )) 40 parts Polyvinyl alcohol (10%) 20 parts [Preparation of high-temperature coloring layer coating liquid] Liquid (developer dispersion liquid) 36.0 parts Liquid (black leuco dye dispersion liquid) 13.8 parts Silicon oxide pigment (25% dispersion; Mizukasil P-527 (manufactured by Mizusawa Chemical)) 20 parts Polyvinyl alcohol (10%) 20 parts The adjusted coating solution of the high-temperature coloring layer was applied 5.0 g on one side of a 50 g / m ² base paper. / M ² , followed by drying, and then 4.0 g of a low-temperature coloring layer coating solution.
/ M ^2, and the sheet was treated with a super calendar so that the smoothness was 500 to 600 seconds to obtain a two-color heat-sensitive recording material.

Example 2 A two-color thermosensitive recording medium was produced in the same manner as in Example 1. However, in preparing the coating solution for the high-temperature coloring layer, no silicon oxide pigment was added.

Examples 3 to 10 Two-color thermosensitive recording media were produced in the same manner as in Example 2. However, in preparing the solution, compound (1-2) (Example 3) and compound (1-1)
3) (Example 4), compound (1-17) (Example 5),
The compounds of Synthesis Examples 1 to 5 (Examples 6 to 10) were used.

Example 11 A two-color thermosensitive recording medium was produced in the same manner as in Example 6. However, when preparing the solution,
2,4'-Sulfonyldiphenol was used instead of -hydroxy-4'-isopropoxydiphenylsulfone.

[Examples 12 and 13] In the same manner as in Example 6, a thermosensitive recording medium was produced. However, in preparing the solution,
Instead of 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-
2-methylindol-3-yl) -4-azaphthalide (blue-colored leuco dye; Example 12), 3,3-bis (1
-N-butyl-2-methylindol-3-yl) phthalide (red coloring leuco dye; Example 13) was used.

[Examples 14 to 16] In the same manner as in Example 6, a thermosensitive recording medium was produced. However, in preparing the solution,
Instead of 3-dibutyl-7- (o-chloroanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran (black leuco dye; Example 1)
4), 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluoran (black developing leuco dye; Example 15) and 3-dibutylamino-6-methyl-7-
Anilino fluoran (black leuco dye; Example 16)
Was used.

Comparative Example 1 A thermosensitive recording medium was produced in the same manner as in Example 6. However, in preparing the solution, Synthesis Example 1
4,4′-sulfonyldiphenol (bisphenol S) was used in place of the compound of formula (1).

<Evaluation Method> Using a thermal printer manufactured by MARKPOINT (with a thermal head manufactured by ROHN, equipped with KM2004-A3), the applied energy of 0.076 mj / dot as low-temperature coloring and high-temperature Printing was performed at 0.219 mj / dot as color development, and the obtained image and background were measured using a Macbeth densitometer (RD-914). In the measurement, the Macbeth densitometer filter used a red filter when evaluating a blue color image, a green filter when evaluating a red color image, and an amber filter when evaluating a black color image and background. .

Next, as a heat resistance test, the obtained low-temperature coloring sample was allowed to stand at 60 ° C. in a dry high-temperature atmosphere for 24 hours to obtain a low-energy printing portion (0.076 mj / do).
The color tone of t) was evaluated with a Macbeth densitometer and visually, and the degree of ground color development was evaluated with a Macbeth densitometer.

The plasticizer resistance test was conducted by winding PVC wrap (Mitsui Toatsu High Wrap KMA) in a single layer around a paper tube.
A high-temperature coloring sample (printed at 0.219 mj / dot) was adhered on the recording medium with the recording surface facing up, and a layer of PVC wrapped three times was further left at 20 ° C. for 24 hours. By measuring the Macbeth concentration of The obtained results are shown in Tables 1 and 2.

[0065]

[Table 1]

[0066]

[Table 2]

(Note) In the table, the symbols in parentheses indicate the filters of the Macbeth densitometer used. R: Red filter,
G: Green filter, A: Amber filter

<Evaluation Results> In Examples 1 to 16 of the present invention,
At a low applied energy (0.076 mj / dot) and a high applied energy (0.219 mj / dot), a sufficient recording density and a clear color tone were obtained. In addition, even after the heat resistance test, the fog of the low energy printing part (black fog)
The color separation was clearly maintained, and the high-temperature coloring image showed excellent preservability. On the other hand, in Comparative Example 1 in which a developing agent other than the one specified in the present invention was used in the high-temperature coloring layer, although the recording density and color separation during recording were satisfactory, the low-energy The image cannot maintain the original color tone and is discolored to black, and the ground color is larger than that of the present invention, the heat resistance is inferior, and the plasticizer resistance of the high-temperature color image is inferior. Was.

[0069]

The multicolor heat-sensitive recording material of the present invention has a high recording density in each color tone, provides clear color development, and shows clear color separation even when exposed to high temperatures. It is extremely useful. Furthermore, since there is little background color development at high temperatures and the preservability of high-temperature color-developed images is high, it is suitable for applications requiring heat resistance and image preservability, and has a high practical value.

Continued on the front page (72) Inventor Yoshimi Midorikawa 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo Japan Paper Manufacturing Co., Ltd. (72) Inventor Yoshihide Kimura 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo Japan Paper Machinery F-term in Product Development Laboratory Co., Ltd. (reference) 2H026 AA07 AA14 AA28 BB30 FF07

Claims (1)

[Claims] 1. A high-temperature coloring layer containing a dye precursor and an organic developer which reacts with the dye precursor under heating to form a color on a support, and forms a color tone different from that of the high-temperature coloring layer. At least one low-temperature coloring layer which exhibits a color at a temperature lower than the temperature at which the high-temperature coloring layer develops is sequentially provided, and a diphenylsulfone cross-linked type represented by the following general formula (1) is used as an organic developer of the high-temperature coloring layer. A multicolor heat-sensitive recording material comprising a compound. Embedded image [In the formula, X and Y each represent a hydrocarbon group which may be different from each other and may have a linear or branched saturated or unsaturated carbon atom having 1 to 12 carbon atoms, or may have an ether bond. Or Or (R represents a methylene group or an ethylene group, T represents a hydrogen atom or a C ₁ -C ₄ alkyl group). R _{1 to} R ₆ are each independently a halogen atom, a C _{1 to} C ₆ alkyl group,
Shows an alkenyl group. Also, m, n, p, q, r, and t are 0
Represents an integer of up to 4, and when it is 2 or more, R _{1 to} R ₆ may be different from each other. a represents an integer of 0 to 10. ]