JPH06328859A - Heat-sensitive recording body - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the color development performance of a thermosensitive recording medium and to improve the oil resistance and plasticizer resistance of the color development image, thereby enhancing the long-term stability of the color development image. [Structure] In a thermosensitive coloring layer, a dye precursor and a compound of formula (I)
Group of: A developer compound having (R ¹ = lower alkyl group, lower alkoxy group and / or aromatic group substituted or not with a halogen) and a sensitizer compound of the formula (II): (R ^{2 to} R ⁹ = H, halogen, aryl, aryloxy, arylthio, aralkyl, alkyl, alkoxy, nitro, alkylamino, or amino group.
R ^{2 to} R ⁹ are not all H at the same time. ) Containing a thermal recording material.

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 which forms a colored image by heating, and more specifically, there is no loss of the once-colored image and excellent storage stability of the recorded image. The present invention also relates to a thermosensitive recording material having high recording sensitivity. Such a thermal recording material has good long-term storage stability of the recording, and at the same time has excellent water resistance, oil resistance, and plasticizer resistance of the recorded image, so that the image recording paper, cash dispenser paper, ticket, It is useful as a commuter pass, a label such as a POS label, a card such as a prepaid card, and a pass ticket.

[0002]

2. Description of the Related Art A thermal recording material is generally composed of a support such as paper, synthetic paper or plastic film on which a color-forming substance such as an electron-donating leuco dye and an organic acid substance such as an electron-accepting phenolic compound. A thermosensitive coloring layer containing a color-developing substance as described above as a main component is provided, and a recorded image can be obtained by reacting these coloring components with thermal energy. Such a thermal recording material is disclosed in Japanese Examined Patent Publication No. 43-40.
No. 60, Japanese Patent Publication No. 45-14039, and Japanese Patent Laid-Open No. 48-
It is disclosed in Japanese Patent No. 27736 and is widely put into practical use.

The thermosensitive recording medium having the above-mentioned structure is a printer of an electronic computer output, a facsimile machine, an automatic ticket vending machine, and a scientific measuring instrument because the recording device used is compact, inexpensive and easy to maintain. Alternatively, it is widely used in printers for CRT medical measurement. However, in a conventional so-called dye-type thermosensitive recording medium in which a thermosensitive coloring layer containing a color-developing dye substance, a color-developing substance and a binder as an active ingredient is coated on a support, the coloring reaction is reversible. For this reason, it is known that a colored image disappears over time. This decolorization is accelerated by exposure to light, high humidity, and high temperature atmosphere, and further significantly left by leaving it in water for a long time, contact with oil such as salad oil, and a plasticizer,
The image is erased to an unreadable level.

A number of techniques have been disclosed for suppressing the above-mentioned decoloring phenomenon when a coloring system using a dye precursor mainly composed of a colorless or light-colored lactone ring compound is used. For example, JP-A-60-78782 and JP-A-59-1
No. 67292, JP-A-59-114096, and JP-A-59-93387, a compound containing a phenolic antioxidant in a thermosensitive color-developing layer, JP-A-
As disclosed in JP-A-6-146794, a composition in which a hydrophobic polymer compound emulsion or the like is used for a protective layer, Japanese Patent Laid-Open No.
No. 8-199189, a water-soluble polymer compound or a hydrophobic polymer compound emulsion is provided as an intermediate layer on the heat-sensitive color-developing layer, and an oil-based paint containing the hydrophobic polymer compound as a resin component is formed thereon. Those provided with a surface layer, those using a phenol-based developer in combination with an epoxy compound as seen in JP-A-62-164579, and specific salicylic acids as seen in JP-A-62-169681. It is known that a metal salt of a derivative is used as a developer.

In the heat-sensitive color-developing layer containing the above-mentioned phenolic antioxidant, oil resistance (for example, image density after a certain period of time when salad oil is brought into contact with the color-developing surface) is higher than that of the image in the absence thereof. Storage ratio), plasticizer resistance (storage ratio of image density after a certain period of time when a plasticizer-containing wrap film or the like is brought into contact with the coloring surface), and the like are not observed.

Further, although the thermal recording medium provided with a protective layer and a surface layer suppresses the color fading of an image when it is contacted with oil or a plasticizer for a short time, it is erased by a contact for a long time. Color is inevitable and cannot be said to be an essential solution to the above problems.

Further, in the thermosensitive recording medium in which a phenol compound and an epoxy compound are used in combination, a relatively long time is required from the heating color development operation until the color image is stabilized. For example, the color image immediately after color development is formed. When salad oil is applied to or brought into contact with a plasticizer, a considerable part of the color image is erased.

Further, the thermal recording material using a specific salicylic acid metal salt has improved image storability, but a blank part was found in the heat resistance test, and the effective chemical structure of the specific salicylic acid was complicated. It has the disadvantage of being expensive.

Further, in general, a heat-sensitive recording material having a high storability often has a drawback that it has a relatively low sensitivity because it has no choice but to add an additive and to use a somewhat special coloring material.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and provides a thermosensitive recording medium which is excellent in long-term storage stability of a color image such as oil resistance and plasticizer resistance and has high sensitivity. It is what Further, the present invention can be used not only as a heat-sensitive recording type ticket for an automatic ticket vending machine, but also as a coupon ticket or a commuter ticket that requires preservation,
Not only is it suitable as a label for POS bar code system that is attached to the packaging surface of foods that are packaged with polyvinyl chloride film that cannot avoid contact with plasticizers and fats and oils,
An object of the present invention is to provide a thermal recording material that can be used as facsimile paper or word processing paper for long-term storage that requires high sensitivity, and also as image printer paper for CRT.

[0011]

DISCLOSURE OF THE INVENTION The present inventors have studied to develop a thermosensitive recording paper having high storage stability of a color image and having high sensitivity, and as a result, the arylsulfonylureido group has been developed. Using the contained compound as a developer,
Moreover, it was discovered that the above object can be achieved by using a specific benzophenone compound as a sensitizer together with this, and the present invention has been completed.

The heat-sensitive recording material of the present invention comprises a sheet-shaped substrate,
Formed on at least one surface of the sheet-like substrate, and
A colorless or light-colored dye precursor, and a thermosensitive coloring layer containing a color developing agent that reacts with the dye precursor under heating to develop a color, and the following general formula (I) as the color developing agent:

[Chemical 3] (Wherein R ¹ represents an aromatic group which is unsubstituted or substituted by at least one member selected from a lower alkyl group, a lower alkoxy group and a halogen atom) in at least one molecule. The thermosensitive coloring layer further comprises a compound of the following general formula (II):

[Chemical 4] (However, R ^{2 to} R ⁹ are each independently a hydrogen atom, an aryl group, an aryloxy group, an arylthio group,
Aralkyl group, alkyl group, alkoxy group, nitro group,
It represents a member selected from a halogen atom, an alkylamino group, and an amino group. However, not all of R ^{2 to} R ⁹ are hydrogen atoms at the same time. ) And at least one benzophenone compound represented by

[0013]

The part of the benzophenone compound represented by the general formula (II) is replaced with 2,2-bis (4-hydroxyphenyl)
The use as a heat-fusible substance of a phenolic developer represented by propane (that is, bisphenol A) is disclosed in JP-A-61-112689 and JP-A-61-11-1.
16584, JP 62-11677, JP 62
As disclosed in JP-A-28286, JP-A-64-40373, etc., when a phenolic developer and these heat-fusible substances are combined, the resulting thermosensitive coloring layer has a low whiteness and a long-term It has a drawback that it easily causes fog during storage. In addition, the obtained color image has poor storability and has a defect that the color image is erased in a short time due to contact with oil or a plasticizer. In the present invention, the above-mentioned drawbacks are solved by using the above specific arylsulfonylureido group-containing compound as a color developer.

The compound having at least one arylsulfonylureido group of the formula (I) used as a color developer in the present invention does not have an acidic functional group such as a phenolic hydroxyl group or a carboxyl group, but has a basic group. It exhibits a strong color development ability with respect to leuco dyes. This is because the urea group in the arylsulfonylureido group of formula (I) is
It is considered that it is activated by the sulfonyl group adjacent to it.

In the specific developer compound of the present invention, the group bonded to the arylsulfonylureido group of formula (I) is not particularly limited. Specific examples of the compound having at least one arylsulfonylureido group of the formula (I) are as follows. (1) Having one arylsulfonylureido group N- (p-toluenesulfonyl) -N'-phenylurea (melting point 165 ° C), N- (p-toluenesulfonyl)-
N '-(p-methoxyphenyl) urea (melting point 155
C), N- (p-toluenesulfonyl) -N '-(o-
Tolyl) urea (melting point 148 ° C.), N- (p-toluenesulfonyl) -N ′-(m-tolyl) urea (melting point 184
C), N- (p-toluenesulfonyl) -N '-(p-
Tolyl) urea (melting point 149 ° C.), N- (p-toluenesulfonyl) -N ′-(pn-butylphenyl) urea,
N- (p-toluenesulfonyl) -N ′, N′-diphenylurea (melting point 159 ° C.), N- (p-toluenesulfonyl) -N ′-(o-chlorophenyl) urea (melting point 18
0 ° C.), N- (p-toluenesulfonyl) -N ′-(m
-Chlorophenyl) urea (melting point 193 ° C), N- (p-
Toluenesulfonyl) -N '-(2,4-dichlorophenyl) urea, N- (p-toluenesulfonyl) -N'-
Methyl-N'-phenylurea (melting point 155 ° C), N-
(P-Toluenesulfonyl) -N′-benzylurea (melting point 177 ° C.), N- (p-toluenesulfonyl) -N ′
-(1-naphthyl) urea (melting point 124 ° C), N- (p-
Toluenesulfonyl) -N '-(1- (2-methylnaphthyl)) urea, N- (benzenesulfonyl) -N'-phenylurea (melting point 153 ° C), N- (p-chlorobenzenesulfonyl) -N'-phenyl Urea, N- (o-toluenesulfonyl) -N'-phenylurea, N- (p-toluenesulfonyl) -N'-methylurea (melting point 172
C.), N- (p-toluenesulfonyl) -N′-ethylurea (melting point 141 ° C.), N- (p-toluenesulfonyl) -N ′-(2-phenoxyethyl) urea (melting point 19
1 ° C.), N, N′-bis (p-toluenesulfonyl) urea (melting point 155 ° C.), N- (p-toluenesulfonyl)
-N '-(o-diphenyl) urea (melting point 148 ° C), N
-(P-toluenesulfonyl) -N '-(p-ethoxycarbonylphenyl) urea, N- (p-toluenesulfonyl) -N'-butylurea (melting point 126 ° C), N- (p
-Chlorobenzenesulfonyl) -N'-propylurea (melting point 127 ° C), N- (p-methoxybenzenesulfonyl) -N'-phenylurea (melting point 149 ° C) and the like.

(2) Having two or more arylsulfonylureido groups Bis {N '-(p-toluenesulfonyl) ureido} ketone, 1,2-bis {N'-(p-toluenesulfonyl) ureido} ethane , 1,1,6,6-tetra {N '
-(P-toluenesulfonyl) ureido} heptane,
1,5-bis {N '-(p-toluenesulfonyl) ureido} -3-oxapentane, 1,5-bis {N'-
(P-Toluenesulfonyl) ureido} -3-thiopentane, 1,3-bis {N '-(p-toluenesulfonyl) ureido} -2-propanone, 1,5-bis {N'
-(P-toluenesulfonyl) ureido} -3- [2 '
-{N '-(p-toluenesulfonyl) ureido} ethyl] -3-azapentane, 1,3-bis {N'-(p-
Toluenesulfonyl) ureido-N-methyl} -benzene, 1,4-bis {N '-(p-toluenesulfonyl)
Ureido-N-methyl} -benzene, 4,4'-bis {N '-(p-toluenesulfonyl) ureido} -diphenylmethane, 4,4'-bis {N'-(o-toluenesulfonyl) ureido} -diphenylmethane , 4, 4 '
-Bis (benzenesulfonylureido) -diphenylmethane, 4,4'-bis (1-naphthalenesulfonylureido) -diphenylmethane, 2,2-bis [4 ', 4 "
-{N '-(p-toluenesulfonyl) ureido} phenyl] propane, 1,2-bis [4'-{N '-(p-
Toluenesulfonyl) ureido} phenyloxy] ethane, 2,5-bis [{N '-(p-toluenesulfonyl) ureido} methyl] furan, 1,3-bis {N'-
(P-toluenesulfonyl) ureido} benzene, 1,
4-bis {N '-(p-toluenesulfonyl) ureido} benzene, 1,5-bis {N'-(p-toluenesulfonyl) ureido} naphthalene, 1,8-bis {N '
-(P-toluenesulfonyl) ureido} naphthalene,
4,4'-bis {N '-(p-toluenesulfonyl) ureido} diphenyl ether, 3,3'-bis {N'-
(P-Toluenesulfonyl) ureido} diphenylsulfone, 4,4'-bis {N '-(p-toluenesulfonyl) ureido} diphenylsulfone, 2,4-bis {N'-(p-toluenesulfonyl) ureido} toluene , 2,6-bis {N '-(p-toluenesulfonyl)
Ureido} toluene, 4,4′-bis {N ′-(p-toluenesulfonyl) ureido} diphenyl sulfide,
3,4'-bis {N '-(p-toluenesulfonyl) ureido} diphenyl ether and the like.

These compounds may be used alone or in combination of two or more.

The melting point of the heat-fusible compound represented by the formula (II) of the present invention is preferably 60 to 180 ° C.
When the melting point is less than 60 ° C., there may be a drawback that an undesired color reaction is induced during the production of the heat-sensitive recording material or the whiteness of the obtained heat-sensitive recording material is lowered. If the melting point exceeds 180 ° C., it becomes difficult to obtain a high-sensitivity thermal recording material.

Specific examples of the benzophenone compound represented by the formula (II) used in the present invention are as follows. 4-methylbenzophenone (melting point 59 ° C.), 4
-Methoxybenzophenone (melting point 60 ° C), 4-phenylbenzophenone (melting point 102 ° C), 4-chlorobenzophenone (melting point 76 ° C), 3-chlorobenzophenone (melting point 82 ° C), 3-bromobenzophenone (melting point 74)
℃), 4-bromobenzophenone (melting point 81 ℃), 4-
Nitrobenzophenone (melting point 136 ° C.), 3-nitrobenzophenone (melting point 93 ° C.), 4-aminobenzophenone (melting point 123 ° C.), 2-aminobenzophenone (melting point 108 ° C.), 4-benzoyl-4′-methyldiphenyl sulfide (melting point 83 ° C.), 4,4′-dichlorobenzophenone (melting point 147 ° C.), 3,4′-dichlorobenzophenone (melting point 112 ° C.), 2,5-dichlorobenzophenone (melting point 88 ° C.), 2,6-dichlorobenzophenone (melting point 86 ° C.), 3,4-dichlorobenzophenone (melting point 104 ° C.), 3,5-dichlorobenzophenone (melting point 65 ° C.), 3,3′-dichlorobenzophenone (melting point 123 ° C.), 4-chloro-4′-bromobenzophenone (Melting point 150 ° C.), 4-chloro-2′-nitrobenzophenone (melting point 15 C.), 4,4′-dibromobenzophenone (melting point 178 ° C.), 3,3′-diaminobenzophenone (melting point 153 ° C.), 4,4′-diethylaminobenzophenone (melting point 94 ° C.), 4,4′-dimethylaminobenzophenone , 4,4'-difluorobenzophenone (melting point 108 ° C), 4,4'-dimethoxybenzophenone (melting point 145 ° C), 4,4'-dimethylbenzophenone (melting point 95 ° C), 3,4'-dimethylbenzophenone (melting point 72 ° C.), 3,5-dimethylbenzophenone (melting point 70 ° C.), 3,3′-dinitrobenzophenone (melting point 156 ° C.), 2-chloro-4′-methylbenzophenone (melting point 100 ° C.), 3-chloro-4 ′. -Methylbenzophenone (melting point 97 ° C), 4-chloro-4'-methylbenzophenone (melting point 128 ° C), 2, , 4'-trichloro-benzophenone (melting point 64 ℃), 2,4,3 '
-Trichlorobenzophenone (melting point 145 ° C), 2,
2 ', 4,5'-Tetrachlorobenzophenone (melting point 1
76 ° C.), 3,3 ′, 4,4′-tetrachlorobenzophenone (melting point 144 ° C.), 2,3,4,5,6-pentachlorobenzophenone (melting point 154 ° C.), 2,5-dichloro-2 ′ -Methylbenzophenone (melting point 64 ° C),
2,4-dichloro-5-methylbenzophenone (melting point 7
8 ° C.), 2,4,4′-trichloro-2 ′, 5′-dimethylbenzophenone (melting point 84 ° C.), 2,2′-dichloro-5,5′-dimethylbenzophenone (melting point 70)
° C), 2-chloro-6,4'-dimethyl-3-nitrobenzophenone (melting point 105 ° C), 4-chloro-2 ',
4 ', 6'-trimethylbenzophenone (melting point 68
° C), 2-bromo-2 ', 4', 6'-trimethylbenzophenone (melting point 113 ° C), 3-bromo-2 ',
4 ', 6'-trimethylbenzophenone (melting point 86
C.), 4-bromo-2 ′, 4 ′, 6′-trimethylbenzophenone (melting point 72 ° C.), 2-nitro-2 ′, 4 ′,
6'-trimethylbenzophenone (melting point 146 ° C),
2,6,2'-Trimethylbenzophenone (melting point 69
C.), 4-chloro-4′-tertbutylbenzophenone (melting point 79 ° C.), 2,2 ′, 3,3′-tetramethylbenzophenone (melting point 80 ° C.), 2,3,5,6-tetramethylbenzophenone ( Melting point 119 ° C), 2, 2 ',
4,6, -Tetramethylbenzophenone (melting point 111
° C), 2,4,6,3'-tetramethylbenzophenone (melting point 67 ° C), 2,2 ', 6,6'-tetramethylbenzophenone (melting point 134 ° C), 3,3', 4,4'-
Tetramethylbenzophenone (melting point 140 ° C), 3,
3 ', 5,5'-tetramethylbenzophenone (melting point 1
10 ° C.), 2,3,4,5,6-pentamethylbenzophenone (melting point 135 ° C.), 2,2 ′, 3,5,6-pentamethylbenzophenone (melting point 112 ° C.), 2,3,3
3 ', 5,6-pentamethylbenzophenone (melting point 11
1 ° C.), 2,3,5,6,4′-pentamethylbenzophenone (melting point 144 ° C.), 3,3 ′, 4,4 ′, 6-pentamethylbenzophenone (melting point 77 ° C.), 2,2 ′,
6,6 ', 4-pentamethylbenzophenone (melting point 86
° C), 2,2 ', 4,4', 6,6'-hexamethylbenzophenone (melting point 135 ° C), 2,6-dimethyl-4
-Tert-butylbenzophenone (melting point 108 ° C),
4,4'-ditertbutylbenzophenone (melting point 13
8 ° C.), 4,4′-dibenzylbenzophenone, 4,
4'-diphenoxybenzophenone (melting point 138 ° C) and the like.

In the present invention, the leuco dye used as the dye precursor can be selected from conventionally known ones such as triphenylmethane type, fluorane type and diphenylmethane type compounds. As such a dye precursor,
For example, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindole-3
-Yl) -4-azaphthalide, crystal violet lactone, 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinoflu Oran, 3
-Diethylamino-6-methyl-7- (o, p-dimethylanilino) fluorane, 3- (N-ethyl-Np-
Toluidino) -6-methyl-7-anilinofluorane,
3-pyrrolidino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7- Anilinofluorane, 3-diethylamino-7- (o-chloroanilino) fluorane,
3-dibutylamino-7- (m-trifluoromethylanilino) fluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6-methylfluorane, and 3-cyclohexylamino-6.
-Chlorofluorane, 3- (N-ethyl-N-hexylamino) -6-methyl-7- (p-chloroanilino) fluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3- Dibutylamino-
One or more selected from 7- (o-chloroanilino) fluorane, 3-dipentylamino-6-methyl-7-anilinofluorane and the like can be used.

The thermosensitive coloring layer of the present invention may further contain an aromatic compound having at least one epoxy ring and / or an aromatic compound having at least one aziridinyl group. Examples of those compounds are:
JP-A-62-164579 and JP-A-2-220885
JP-A-2-255376, and specific examples thereof include the following compounds. 4,4'-bis (2 ", 3" -epoxypropyloxy) diphenyl sulfone, 2,2-bis (4 '
-(2 ", 3" -epoxypropyloxy) phenyl)
Propane, 1,4-bis (2 ', 3'-epoxypropyloxy) benzene, 4- (2'-methyl-2', 3 '
-Epoxypropyloxy) -4'-benzyloxy-
Diphenyl sulfone, 4- (2 ", 3" -epoxypropyloxy) -4 '-(p-methylbenzyloxy)-
Diphenyl sulfone, epoxidized ortho novolac cresol resin, 4,4'-bis (2 ", 3" -epoxypropyloxy) diphenylmethane, 4,4'-bis (2 ", 3" -epoxypropylamino) diphenylmethane, bis ( 2 ", 3" -epoxypropyl) -4,
4'-methylenedibenzoate, 4,4'-bis (2 ", 3" -epoxypropyloxy) biphenyl,
4,4'-bis (2 ", 3" -epoxypropyloxy), 3,3 ', 5,5'-tetramethylbiphenyl,
2,6-bis (2 ', 3'-epoxypropyloxy)
Naphthalene, bis (2,3-epoxypropyl) terephthalate, 2,4-bis (1-aziridinylcarbonylamino) toluene, bis (4- (1-aziridinylcarbonylamino) phenyl) methane, bis (3- Chloro-
4- (1-aziridinylcarbonylamino) phenyl)
Methane, 2,2-bis (4- (1-aziridinylcarbonyloxy) phenyl) propane, 1,4-bis (1-
Aziridinylcarbonyloxy) benzene, 1,4-bis (1-aziridinylcarbonyl) benzene.

Further, in the present invention, a conventionally known developer consisting of a phenol or an organic acid may be used in an amount of one or more arylsulfonylureido groups of the formula (I) of the present invention within a range that does not inhibit a desired effect. The compound can be used in combination. Examples of these conventional developers include 2,2-
Bis (4-hydroxyphenyl) propane (bisphenol A), 1,1-bis (4-hydroxyphenyl)-
1-phenylethane, 1,4-bis (1-methyl-1-)
(4'-hydroxyphenyl) ethyl) benzene, 1,
3-bis (1-methyl-1- (4'-hydroxyphenyl) ethyl) benzene, dihydroxyphenyl ether (JP-A-1-180382), benzyl p-hydroxybenzoate (JP-A-52-140483), bisphenol S, 4-hydroxy-4'-isopropyloxydiphenyl sulfone (JP-A-60-13852),
1,1-di (4-hydroxyphenyl) cyclohexane, 1,7-di (4-hydroxyphenylthio) -3,
5-dioxaheptane (JP-A-59-52694),
3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone (JP-A-60-208286) and the like are known.

Further, in the present invention, a heat-fusible substance (sensitizer) different from the benzophenone compound of the formula (II) of the present invention may be used in combination within a range that does not impair the desired effect. A typical example thereof is 1-hydroxy-
2-Naphthoic acid phenyl ester (JP-A-57-191
086), p-benzylbiphenyl (JP-A-60-8).
2382), benzylnaphthyl ether (JP-A-58)
-87094), dibenzyl terephthalate (JP-A-58-98285), benzyl p-benzyloxybenzoate (JP-A-57-201691), diphenyl carbonate, ditolyl carbonate (JP-A-58-136489), m
-Terphenyl (JP-A-57-89994), 1,2
-Bis (m-tolyloxy) ethane (JP-A-60-56)
588), 1,5-bis (p-methoxyphenoxy)
-3-Oxapentane (JP-A-62-181183)
No.), oxalic acid diesters (JP-A-64-1583).
No.), 1,4-bis (p-tolyloxy) benzene (Japanese Patent Laid-Open No. 2-153783) and the like.

The heat-sensitive color developing layer of the present invention may further contain a hindered phenol compound or an ultraviolet absorber. They are, for example, JP-A-57-151394, JP-A-58-160191, and JP-A-58-69096.
JP-A-59-2884, JP-A-59-95190
JP-A-60-22288 and JP-A-60-2554.
85, JP-A-61-44686, JP-A-62-16
9683, JP-A-63-17081, JP-A 1-2
49385, JP-A-4-144786, and the like. Specific examples include 1,1,3-
Tris (3'-cyclohexyl-4'-hydroxyphenyl) butane, 1,1,3-tris (2-methyl-4-)
Hydroxy-5-cyclohexylphenyl) butane,
1,1,3-tris (2-methyl-4-hydroxy-5)
-Tert-butylphenyl) butane, 4,4'-thiobis (3-methyl-6-tert-butylphenol), 1,3,5-trimethyl-2,4,6-tris (3,5-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 and the like.

The heat-sensitive color forming layer of the heat-sensitive recording material of the present invention mainly comprises a dye precursor, a compound having at least one arylsulfonylureido group of the above formula (I) as a developer, and a heat-fusible substance. It includes a benzophenone compound of the formula (II). The thermosensitive coloring layer further, if necessary,
A compound having an epoxy group and / or a compound having an aziridinyl group, a conventionally known phenol-based or organic acid-based color developer, antioxidant, ultraviolet absorber, or wax can be included. Further, it preferably contains organic or inorganic pigments. Further, the thermosensitive coloring layer contains a binder for fixing these components to the support.

The content of the above-mentioned dye precursor in the thermosensitive coloring layer is generally preferably 5 to 20% by weight based on the dry weight of the thermosensitive coloring layer, and the aryl of the formula (I) of the present invention in the thermosensitive coloring layer. The content of the color-developing compound having one or more sulfonylureido groups is generally 5 to 50% by weight.
Is preferred. If the content is less than 5% by weight, the color developing ability becomes insufficient, and even if it is used in a large amount exceeding 50% by weight, the color developing ability is saturated and no remarkable improvement is seen, which is economically disadvantageous. May be. The formula (I
The content of the compound of I) which is a heat-fusible benzophenone is preferably 5 to 50% by weight based on the weight of the thermosensitive coloring layer. If it is added less than 5%, the sensitizing effect is small, and if it is added in excess of 50%, the sensitizing effect is saturated and further increase in sensitivity cannot be expected.

The thermosensitive coloring layer contains an epoxy compound or /
When the aziridine compound is contained, the content thereof is preferably 1 to 30% by weight based on the weight of the thermosensitive coloring layer. When the antioxidant or the ultraviolet absorber is contained, its content is preferably 1 to 10% by weight. When a conventionally known phenol-based or organic acid-based color developer is used in combination, the content is preferably 5 to 40% by weight, and when a conventionally-known sensitizer is used in combination, the content is 10-40% by weight is preferred. When waxes and white pigments are contained in the thermosensitive coloring layer, their content is preferably 2 to 20% by weight and 2 to 50% by weight, respectively, and the content of the binder is generally 5 to 20% by weight. .

Examples of the above-mentioned organic or inorganic pigments include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, calcined clay, talc, and surface-treated calcium carbonate. Inorganic fine powder such as silica and silica, urea-formalin resin, styrene / methacrylic acid copolymer,
And organic fine powder such as polystyrene resin.

As the waxes, known waxes such as paraffin, amide wax, bisimide wax, and metal salt of higher fatty acid can be used.

Regarding the binder, polyvinyl alcohol, starch and derivatives thereof of various molecular weights,
Cellulose derivatives such as methoxycellulose, carboxymethylcellulose, methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, styrene / Water-soluble polymeric material such as alkali salt of maleic anhydride copolymer, polyacrylamide, sodium alginate, gelatin, and casein, and
Polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylic ester,
Each latex such as vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, and styrene / butadiene / acrylic copolymer can be used.

The sheet-like substrate used in the heat-sensitive recording material of the present invention is paper, coated paper whose surface is coated with a pigment, latex or the like, laminated paper, synthetic paper made from polyolefin resin, plastic film and the like. You can choose from. At least one surface of such a sheet-like substrate is coated with a coating solution containing a mixture of the above-mentioned required components and dried to produce a thermosensitive recording medium. The coating amount is preferably 1 to 15 g / m ² in the dried state of the coating liquid layer, and more preferably ² to 10 g / m ² .

In the thermosensitive recording medium of the present invention, a coating layer such as a protective layer or a printing layer can be further formed on the thermosensitive coloring layer.

[0033]

EXAMPLES The present invention will be specifically described with reference to the following examples. Unless otherwise specified, "parts" and "%" in the examples mean "parts by weight" and "% by weight", respectively.

Example 1 A thermosensitive recording paper was prepared by the following procedure . (1) Preparation of pigmented undercoat paper Baking clay (trademark: Ansilex, ENGELHAR
(D company) 85 parts in 320 parts of water to obtain a dispersion, 40 parts of styrene / butadiene copolymer emulsion (solid content 50%), and 10% aqueous solution of oxidized starch 5
A coating solution is prepared by mixing 0 parts of the coating solution,
^On a base paper of 8 g / m ² , the applied amount after drying is 7.0 g /
The pigment-coated paper was prepared by coating so as to be m ² .

[0035] (2) Preparation of Dispersion Liquid Ingredients Amount of A (parts) 3- (N-isopentyl -N- ethylamino) -6-methyl-7-anilinofluoran 20 polyvinyl alcohol 10% solution 10 Water 70 The above The composition was pulverized using a sand grinder until the average particle size became 1 μm or less.

[0036] (3) using a sand grinder to Dispersion Preparation Ingredients Amount of B (parts) N-(p-toluenesulfonyl)-N'-phenylurea 20 polyvinyl alcohol 10% solution 10 Water 70 The composition, average It was pulverized until the particle size became 1 μm or less.

[0037] (4) using a sand grinder to Dispersion Preparation Ingredients Amount of C (parts) 4,4'-dimethyl benzophenone 20 polyvinyl alcohol 10% solution 10 Water 70 The composition, average particle size is 1μm or less Crushed until.

(5) Formation of thermosensitive coloring layer In 60 parts of solution A, 120 parts of solution B, and 120 parts of solution C, 26 parts of calcium carbonate pigment, 12 parts of 25% zinc stearate dispersion solution, 30% paraffin dispersion solution. A coating solution was prepared by mixing 10 parts and 80 parts of a 10% polyvinyl alcohol aqueous solution and stirring. This coating solution was applied to one surface of the pigment-undercoated paper so as to have a coating amount after drying of 5.0 g / m ² and dried to form a thermosensitive color-developing layer to prepare a thermosensitive recording paper.

(6) Test For the sample thus obtained, THP manufactured by Okura Electric Co., Ltd.
Using a MD (a thermal recording paper printing tester, manufactured by Kyocera, equipped with a thermal head), a color development test was performed at a pulse width of 0.7 milliseconds with an applied voltage of 22 V and a line width of 4 milliseconds. The color density of the obtained color image was measured with a Macbeth reflection densitometer RD-914, and this was used to represent the recording sensitivity. Further, the sample was heated for 5 seconds at a temperature of 70 ° C. and a pressure of 0.5 kg / cm ² using a thermal gradient tester manufactured by Toyo Seiki Co., Ltd., and the color density at that time was measured by the densitometer. This measured value is called a static color development characteristic value, and indicates how much the white background density of the sample is maintained at a relatively high temperature.
The test results are shown in Table 1.

Example 2 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, in the preparation of Dispersion C, 4-phenylbenzophenone was used instead of 4,4′-dimethylbenzophenone. The test results are shown in Table 1.

Example 3 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, in the preparation of Dispersion C, 4-chloro-4′-methylbenzophenone was used instead of 4,4′-dimethylbenzophenone. The test results are shown in Table 1.

Example 4 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, in the preparation of Dispersion C, 4-chlorobenzophenone was used instead of 4,4′-dimethylbenzophenone. The test results are shown in Table 1.

Example 5 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, in the preparation of Dispersion A, 3- (N-ethyl-N-
3-Dibutylamino-6-methyl-7 instead of isopentylamino) -6-methyl-7-anilinofluorane
-Using anilinofluorane, and in the preparation of dispersion B, N- (p-toluenesulfonyl) instead of N- (p-toluenesulfonyl) -N'-phenylurea
-N '-(p-methoxyphenyl) urea was used. The test results are shown in Table 1.

Comparative Example 1 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, in the formation of the thermosensitive coloring layer, the dispersion C was not mixed in the coating liquid. The test results are shown in Table 1.

Comparative Example 2 A thermosensitive recording paper was prepared in the same manner as in Example 1. However, in the preparation of Dispersion C, p-benzylbiphenyl was used instead of 4,4′-dimethylbenzophenone. The test results are shown in Table 1.

Comparative Example 3 A thermal recording paper was prepared in the same manner as in Example 1. However, in preparing the dispersion liquid B, 2,2-bis (4-hydroxyphenyl) propane (that is, bisphenol A) was used instead of N- (p-toluenesulfonyl) -N′-phenylurea. The test results are shown in Table 1.

[0047]

[Table 1]

As is clear from Table 1, when a compound having an arylsulfonylaminoureido group is used as a color developing agent, a heat-sensitive color development obtained by using a heat-fusible substance represented by the general formula (II) in combination. The layer exhibits a high sensitizing effect, exhibits a coloring ability comparable to that of bisphenol A which is a representative of conventional color developing agents, and does not cause a problem of blank background fogging. Further, it exhibits a higher sensitizing effect on bisphenol A than p-benzylbiphenyl, which has an excellent sensitizing effect.

Example 6 A thermosensitive recording paper was prepared in the same manner as in Example 1.
However, in the preparation of the dispersion liquid B, 4,4 ′ was used instead of N- (p-toluenesulfonyl) -N′-phenylurea.
-Bis {N '-(p-toluenesulfonyl) ureido}
Diphenylmethane was used.

Test The prepared sample was used with a THPMD (a thermal recording paper printing tester, Kyocera, equipped with a thermal head) manufactured by Okura Electric Co., Ltd., with an applied voltage of 22 V and a line width of 4 milliseconds, and a pulse width of 0. The sample was developed at 7 ms and 1.0 ms. The color density was measured with a Macbeth reflection densitometer RD-914, and the color density at a pulse width of 0.7 milliseconds was used as a value representative of the recording sensitivity. In addition, salad oil or dioctyl phthalate (DOP: a representative plasticizer) was applied to a sample developed with a pulse width of 1.0 millisecond within 30 minutes after the color was developed, and the sample was allowed to stand at room temperature for 30 minutes, and then excess oil was applied. Alternatively, the plasticizer was wiped off, the residual image density was measured with a Macbeth reflection densitometer, and the image retention rate was calculated according to the following formula. Image preservation ratio (%) = (residual image density / color image density before coating) × 100 Test results are shown in Table 2.

Example 7 A thermosensitive recording paper was prepared in the same manner as in Example 6. However, in the preparation of Dispersion C, 4-phenylbenzophenone was used instead of 4,4′-dimethylbenzophenone. The test results are shown in Table 2.

Example 8 A thermosensitive recording paper was prepared in the same manner as in Example 6. However, in the preparation of Dispersion C, 4-chloro-4′-methylbenzophenone was used instead of 4,4′-dimethylbenzophenone. The test results are shown in Table 2.

Example 9 A thermosensitive recording paper was prepared in the same manner as in Example 6. However, in the preparation of Dispersion C, 4-chlorobenzophenone was used instead of 4,4′-dimethylbenzophenone.
The test results are shown in Table 2.

Example 10 A thermosensitive recording paper was prepared in the same manner as in Example 6. However, in the preparation of Dispersion C, 4,4′-dichlorobenzophenone was used instead of 4,4′-dimethylbenzophenone. The test results are shown in Table 2.

Example 11 A thermosensitive recording paper was prepared in the same manner as in Example 6. However, in the preparation of Dispersion C, 4-benzoyl-4′-methyldiphenyl sulfide was used instead of 4,4′-dimethylbenzophenone. The test results are shown in Table 2.

Example 12 A thermosensitive recording paper was prepared in the same manner as in Example 6. However, in the preparation of Dispersion A, 3- (N-isopentyl-N-
Ethylamino) -6-methyl-7-anilinofluorane was replaced with 3-dibutylamino-6-methyl-7-anilinofluorane, and 4,4′- Instead of bis {N '-(p-toluenesulfonyl) ureido} diphenylmethane, 4,4'
-Bis {N '-(p-toluenesulfonyl) ureido}
Diphenyl ether was used. The test results are shown in Table 2.

Example 13 A thermosensitive recording paper was prepared in the same manner as in Example 6 except that the dispersion B was replaced with the dispersion D having the following composition when the thermosensitive color developing layer was formed. Preparation Ingredients Amount of Dispersion D (parts) of 4,4'-bis {N '- (p- toluenesulfonyl) ureido} diphenylmethane 12 N-(p-toluenesulfonyl)-N'-phenyl urea 8 Polyvinyl alcohol 10% Liquid 10 Water 70 The above composition was pulverized using a sand grinder until the average particle size became 1 μm or less. The test results are shown in Table 2.

Example 14 A thermosensitive recording paper was prepared in the same manner as in Example 6. However, when forming the thermosensitive coloring layer, the dispersion liquid E having the following composition was used in place of the dispersion liquid B. Preparation Ingredients Amount of dispersion E (parts) of 4,4'-bis {N '- (p- toluenesulfonyl) ureido} diphenylmethane 12 N-(p-toluenesulfonyl)-N'-butyl urea 8 Polyvinyl alcohol 10% Liquid 10 Water 70 The above composition was pulverized using a sand grinder until the average particle size became 1 μm or less. The test results are shown in Table 2.

Comparative Example 4 A thermal recording paper was prepared in the same manner as in Example 6. However, Dispersion C was not mixed in the formation of the thermosensitive coloring layer. The test results are shown in Table 2.

Comparative Example 5 A thermosensitive recording paper was prepared in the same manner as in Example 6. However, in preparing the dispersion liquid B, 4,4′-bis {N′-
2,2-bis (4-hydroxyphenyl) instead of (p-toluenesulfonyl) ureido} diphenylmethane
Propane (bisphenol A) was used. The test results are shown in Table 2.

[0061]

[Table 2]

As is clear from Table 2, when BPA, which is a representative phenolic color developer, and the heat-fusible substance of the present invention are combined (Comparative Example 5), the oil resistance of the color image obtained and While the plasticizer resistance is remarkably low, when the compound having an arylsulfonylureido group of the present invention and the heat-fusible substance of the present invention are combined, the oil resistance of the resulting color image and the plasticizer resistance are extremely low. Was excellent.

[0063]

INDUSTRIAL APPLICABILITY The heat-sensitive recording material of the present invention contains a compound having one or more arylsulfonylureido groups in one molecule as a developer in the heat-sensitive color forming layer, and further contains a specific compound as a sensitizer. It contains at least one benzophenone compound. Therefore, the thermosensitive color developing layer of the present invention is clearly superior to the thermosensitive color developing layer containing the conventional color developer in the color developing performance. Further, the color image formed on the thermosensitive color developing layer of the present invention exhibits high oil resistance and plasticizer resistance immediately after color development. That is, the heat-sensitive recording material of the present invention has excellent practicability by using the specific developer compound and the sensitizer in combination.

Claims (1)

[Claims] 1. A sheet-like substrate, a colorless or light-colored dye precursor which is formed on at least one surface of the sheet-like substrate, and a developer which reacts with the dye precursor under heating to develop a color thereof. And a heat-sensitive color-developing layer containing, wherein the developer is represented by the following general formula (I): (Wherein R ¹ represents an unsubstituted or substituted aromatic group substituted by at least one member selected from a lower alkyl group, a lower alkoxy group, and a halogen atom) in one molecule. The thermosensitive coloring layer further comprises a compound represented by the following general formula (II): (However, R ^{2 to} R ⁹ are each independently a hydrogen atom, an aryl group, an aryloxy group, an arylthio group,
Aralkyl group, alkyl group, alkoxy group, nitro group,
It represents a member selected from a halogen atom, an alkylamino group, and an amino group. However, not all of R ^{2 to} R ⁹ are hydrogen atoms at the same time. ) A heat-sensitive recording material comprising at least one benzophenone compound represented by