JP3487037B2 - Thermal recording medium - Google Patents

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 color image by heating, and more particularly to a heat-sensitive recording material which is free from loss of a once-colored image and is excellent in storage stability of recording. More specifically, the present invention has good long-term storage stability of the recording, and at the same time, has excellent moisture resistance of the recorded image, environment resistance such as heat resistance, oil resistance, plasticizer resistance, and whiteness. The present invention relates to a thermosensitive recording medium which is highly useful for image recording paper, facsimile paper, cash dispenser paper, boarding tickets, commuter passes, labels such as POS labels, cards such as prepaid cards and pass tickets.

[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 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, for example, Japanese Patent Publication No.
No. 4160, Japanese Patent Publication No. 45-14039, and Japanese Patent Laid-Open No.
It is disclosed in No. 8-27736 and is widely put into practical use.

The thermosensitive recording medium as described above has a compact and inexpensive recording device and is easy to maintain. Therefore, the output of a computer, a facsimile, an automatic ticket vending machine, a printer of a scientific measuring instrument, or a CRT medical measuring instrument is used. Widely used for printers and the like. 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 decoloring is accelerated under exposure to light, high humidity and high temperature, and further progresses rapidly due to contact with a plasticizer and oil, and the image is decolorized to an unreadable level.

A number of techniques have been disclosed in order to suppress the above-mentioned decoloring phenomenon with respect to a heat-sensitive recording material using a color-forming system using a dye precursor mainly composed of a colorless or light-colored lactone ring compound. For example, JP-A-60-78782
JP-A-59-167292, JP-A-59-114
No. 096 and a phenolic antioxidant as described in JP-A-59-93387 incorporated into a thermosensitive color developing layer, and a hydrophobic polymer compound as disclosed in JP-A-56-146796. An emulsion in which an emulsion or the like is used as a protective layer, or a water-soluble polymer compound or a hydrophobic polymer compound emulsion is provided as an intermediate layer on the thermosensitive coloring layer as seen in JP-A-58-199189. A surface layer formed of an oil-based paint containing a hydrophobic polymer compound as a resin component, and JP-A-62-16
There are known those containing an epoxy compound as disclosed in Japanese Patent No. 4579, and those using a metal salt of a specific salicylic acid derivative found in JP-A No. 62-169681 as a developer. Further, compounds having some chemical commonalities with the present invention are described in JP-A-62-19485, mainly as materials for pressure-sensitive recording paper.

In the heat-sensitive color-developing layer containing the above-mentioned phenolic antioxidant, compared with the image without it,
Although the environmental resistance is somewhat improved, oil resistance (for example, storage ratio of image density after a certain time when salad oil is brought into contact with the color development surface), plasticizer resistance (wrap film containing plasticizer, etc.) No improvement is observed in the storage ratio of the image density after a certain period of time when it is brought into contact with the coloring surface).

On the other hand, the thermal recording medium provided with a protective layer and a surface layer has a slightly improved environmental resistance, but decolorization is inevitable in a long-term test. Regarding oil resistance, the image storability immediately after contact with oil is improved, but the image disappears almost completely as the oil permeates, and it cannot be said to be an essential solution to the above problems. .

Further, in the case of containing an epoxy compound, a relatively long time is required from the heating color development operation to the stabilization of the color image, and for example, salad oil is applied to the color image immediately after color development. If it is exposed to light, or if it is brought into contact with a plasticizer, a considerable part of the color image is erased. Further, the one using a specific salicylic acid metal salt has improved oil resistance and plasticizer resistance, but a white paper part was found in a heat resistance test, and the effective chemical structure of a specific salicylic acid was complicated. It has the disadvantage of being expensive.

Further, with respect to the compounds described in JP-A No. 62-19485, which have some similarities in chemical structure with the present invention, the coloring ability is the same as that of the conventional phenolic materials or Below that, and the color-developed image of the thermal recording paper produced using these materials,
It has a drawback that it discolors quickly when it comes into contact with salad oil or a plasticizer (see Comparative Examples 1 and 2).

[0009]

SUMMARY OF THE INVENTION The present invention solves the above problems of the prior art and improves the oil resistance, plasticizer resistance, moisture resistance, heat resistance, etc. of the colored image, thereby preserving the colored image for a long period of time. The present invention is intended to provide a heat-sensitive recording material having excellent properties and high whiteness.

INDUSTRIAL APPLICABILITY 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 ticket for a number of tickets and a commuter ticket that require preservation, and can be used in contact with a plasticizer and oils and fats. Not only suitable as a label for a POS bar code system that is stuck to the packaging surface of foods that are inevitable polyvinyl chloride film, but also as facsimile paper or word processor paper for long-term storage, or as an image printer paper for CRT. It is intended to provide a thermosensitive recording medium that can be used.

[0011]

DISCLOSURE OF THE INVENTION The inventors of the present invention have developed a thermosensitive color development in which the storage stability-improving effects such as oil resistance and plasticizer resistance of a color image are developed within the shortest possible time after color image formation. A layer improving method was investigated, and as a result, by using at least one color-developing organic compound having at least one functional group having a specific chemical structure in the molecule as a color-developing agent, a high color-developing density was obtained. It was discovered that a heat-sensitive recording material having high whiteness can be obtained, and by using an organic compound containing two or more of the above functional groups in one molecule as a developer, a color image having high resistance to oil and plasticizer. The present invention has been completed by discovering that

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 heat-sensitive color-developing layer containing a color-developing agent that reacts with this dye precursor under heating to develop a color, and the color-developing agent has the following general formula (I):

[Chemical 4] (In the above formula (I), X represents an oxygen atom or a sulfur atom), and at least one type of color-developing organic compound having at least one functional group in the molecule. It is what

In the thermosensitive recording medium of the present invention, the color-developing organic compound is represented by the following general formulas (II) and (III):

[Chemical 5] (However, in the above formulas (II) and (III), R ₁ represents a member selected from a lower alkyl group, an aralkyl group, and an aryl group, and the aromatic ring group constituting the aralkyl group and the aryl group The aromatic ring group may be further substituted with at least one member selected from a lower alkyl group, an alkoxy group, an aryl group, a halogen atom and an acetyl group, and R ₂ is a carbonyl group derived from a monobasic acid or a monobasic group. A sulfonyl group derived from sulfonic acid, a heteroaromatic ring group having a substituted or unsubstituted aromatic ring portion, an alkyl group, an aralkyl group, and a member selected from an aryl group. The aromatic ring group in and the aromatic ring group in the aryl group further include a lower alkyl group, an alkoxy group, an aryl group, a halogen atom, and a hydroxyl group. Which may be substituted by at least one member selected from a group, an acetyl group and a carboxyl group, Y represents a divalent or higher valent organic or inorganic residue, and n represents an integer of 2 or more). It is preferably selected from compounds. In particular, the use of the color-developing organic compound represented by the above formula (III) can further improve the oil resistance and the plasticizer resistance of the color image.

In the heat-sensitive recording material of the present invention, the color-developing organic compound is represented by the following formulas (IV) and (V):

[Chemical 6] However, it is preferable to be selected from 1,3-bis (p-toluenesulfonylaminocarbonylhydrazinocarbonyl) benzene represented by [wherein m represents an integer of 1 or more] and its hydrate. Formulas (IV) and (V) above
The heat-sensitive recording material obtained by using the color-developing organic compound (1) has excellent color density and whiteness, and the color image has excellent oil resistance and plasticizer resistance.

[0015]

In the substituents in the above general formulas (II) and (III), R ₁ represents a member selected from a lower alkyl group, an aralkyl group and an aryl group, and the aromatic ring group in the aralkyl group is , And the aromatic ring group in the aryl group is further a lower alkyl group, an alkoxy group, an aryl group,
It may be substituted with at least one member selected from a halogen atom and an acetyl group. More specifically, R ₁ can be selected from, for example, a methyl group, an ethyl group, a benzyl group, a phenyl group, a p-tolyl group, an o-tolyl group, a p-chlorophenyl group and the like.

R ₂ in the formula (II) is an alkyl group, an aralkyl group, an aryl group [wherein the aromatic ring in the aralkyl group and the aromatic ring group in the aryl group are a lower alkyl group, an alkoxy group, Aryl group, halogen atom,
Hydroxyl group, acetyl group, may be substituted by at least one member selected from a carboxyl group], a heteroaromatic ring having a substituted or unsubstituted aromatic ring portion, a monobasic carboxylic acid residue and a monobasic Represents a member selected from the group of organic sulfonic acid residues. More specifically, R ₂ can represent a methyl group, a phenyl group, a benzyl group, a 2-benzothiazole group, a p-toluenesulfonyl group, an acetyl group, a phenylcarbonyl group, a stearoyl group, or the like.

Y in the formula (III) is not particularly limited as long as it is an organic or inorganic residue having a valence of 2 or more, but preferable examples include the following groups. a: divalent functional group such as carbonyl group, thiocarbonyl group, sulfonyl group, etc. b: polybasic containing two or more carbonyl groups derived from a dibasic carboxylic acid or a polybasic carboxylic acid having a valence higher than that Basic organic acid residue c: Polybasic organic acid residue containing two or more sulfonyl groups derived from a dibasic organic sulfonic acid or a polybasic organic sulfonic acid having a valence of at least 2

D: a divalent or higher valent hydrocarbon group derived from an aliphatic hydrocarbon or an aromatic hydrocarbon e: a carbonyl group, a thiocarbonyl group, an imide group, an imino group, a sulfonyl group, an ester bond in the main chain, Aliphatic hydrocarbon containing at least one selected from oxygen atom and sulfur atom, or selected from carbonyl group, thiocarbonyl group, imide group, imino group, sulfonyl group, ester bond, oxygen atom, and sulfur atom A divalent or higher valent hydrocarbon group derived from an aromatic hydrocarbon consisting of two or more aromatic hydrocarbon groups bonded by one or more.

Of these groups, the following groups are particularly preferable.

[Chemical 7]

Specific examples of the color-developing organic compound according to the present invention include the following. 1,
3-bis (p-toluenesulfonylaminocarbonylhydrazinocarbonyl) benzene (formula (IV)) and its hydrate (formula (V)), N- (p-toluenesulfonylaminocarbonyl) -N'-acetylhydrazine, N-
(P-toluenesulfonylaminocarbonyl) -N'-
Stearoylhydrazine, N- (p-toluenesulfonylaminocarbonyl) -N '-(2-benzothiazoyl) hydrazine, N- (p-toluenesulfonylaminothiocarbonyl) -N'-(phenylcarbonyl) hydrazine, N- ( p-toluenesulfonylaminocarbonyl) -N '-(phenylcarbonyl) hydrazine, N-
(P-toluenesulfonylaminocarbonyl) -N'-
(P-toluenesulfonyl) hydrazine, N- (p-toluenesulfonylaminocarbonyl) -N '-(p-hydroxyphenylcarbonyl) hydrazine, 4,4'-
Bis (p-toluenesulfonylaminocarbonylhydrazinosulfonyl) diphenyl ether, 4,4'-bis (p-toluenesulfonylaminocarbonylhydrazinosulfonyl) diphenylmethane, 4,4'-bis (p-
Toluenesulfonylaminocarbonylhydrazinocarbonyl) diphenyl ether, 1,3-bis (benzenesulfonylaminocarbonylhydrazinocarbonyl) benzene, 1,3-bis (benzenesulfonylaminothiocarbonylhydrazinocarbonyl) benzene, 1,3-bis (o -Toluenesulfonylaminocarbonylhydrazinocarbonyl) benzene, 1,3-bis (p-chlorobenzenesulfonylaminocarbonylhydrazinocarbonyl) benzene. These compounds may be used alone or as a mixture of two or more thereof.

The organic compound having one or more functional groups represented by the formula (I) in one molecule used in the present invention acts as a developer for the dye precursor in the thermosensitive color developing layer. To do. That is, the formula (I)
An organic compound having one or more functional groups in one molecule does not have an acidic functional group such as a phenolic hydroxyl group or a carboxyl group, but has a strong color developing ability with respect to a basic leuco dye. Is shown. Further, the color-developing organic compound of the present color can firmly hold the once-color-developed dye in the color-developed state, and suppress the decoloring reaction of the color-developed dye. Among these excellent properties, it is considered that the strong color developing ability is due to the strong interaction of the sulfonylsemicarbazide group represented by the formula (I) with the dye.

Further, the color-developing organic compound of the present invention has two or more functional groups represented by the formula (I) in one molecule, which is a necessary condition for strong preservation. This means that the compound having only one functional group represented by the formula (I) of the present invention in one molecule has sufficiently high color developing ability, but in the formula (I) of the present invention, It is clear from the fact that the resistance of the colored image to salad oil and plasticizer is considerably poorer than that of the compound having two or more functional groups shown in one molecule.

Almost all of the color-developing organic compounds having one or more functional groups represented by formula (I) in the molecule as described above are novel compounds which have not been reported so far, and their synthesis. Can be performed, for example, by the following reactions (1) and (2).

[Chemical 8] (However, in the above formula, R ₁ , R ₂ , X, Y, and n are the same as described above.) Some of the thus-obtained color-developing organic compounds according to the present invention are A hydrate may be formed during the long-term storage in a humid environment or in the process of dispersion in an aqueous medium, which is performed during the production of a thermosensitive recording medium. For example, the compound represented by the above formula (IV) is hydrated to form the hydrate represented by the above formula (V), in which the value of m is 1 or more, and particularly when the value of m is 4. , There are at least two different hydration states. These hydrated organic compounds are also useful as color developers for heat-sensitive recording materials.

The leuco dye used as the dye precursor in the present invention can be selected from conventionally known triphenylmethane type compounds, fluorane type compounds, diphenylmethane type compounds and the like. Examples of such leuco dyes include 3- (4
-Diethylamino-2-ethoxyphenyl) -3- (1
-Ethyl-2-methylindol-3-yl) -4-azaphthalide, crystal violet lactone, 3-
(N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-
Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluorane, 3- (N-ethyl-N-p-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-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6-methylfluorane,
3-cyclohexylamino-6-chlorofluorane, 3
-(N-ethyl-N-hexylamino) -6-methyl-
7- (p-chloroanilino) fluorane, and 2-chloro-3-methyl-6- (N, N-diethylaminoanilinofluorane, 3- (p-anilinoanilino) -6-
Methyl-7-anilinofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-
Dimethylaminophthalide), 3,3-bis (2- (p-
Dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl) -4,5,6,7-tetrachlorophthalide, bis (p-dimethylaminostyryl) -p-toluenesulfonylmethane, etc. The above can be used.

Further, in the thermosensitive coloring layer of the present invention, the N-structure shown by the following structure is provided within a range that does not inhibit the desired effect.
Arylsulfonylurea derivatives:

[Chemical 9] (In the above formula, R ₃ represents an unsubstituted phenyl group, and a phenyl group substituted with at least one member selected from a halogen atom, a lower alkyl group, an aryl group, an alkoxyl group, an acetyl group, and a nitro group, and R 3 ₄ is substituted with at least one member selected from an aralkyl group, a (unsubstituted) phenyl group, a (unsubstituted) naphthyl group, or an alkoxyl group, an acetyl group, a nitro group, a lower alkyl group, and a halogen atom. A phenyl group or a naphthyl group) or a phenol, or a conventionally known developer comprising an organic acid is used in combination with a color-developing organic compound having a functional group represented by the formula (I) of the present invention. You can

These conventional color developers include, for example, N- (p
-Toluenesulfonyl) -N'-phenylurea, N-
(P-Toluenesulfonyl) -N '-(p-methoxyphenyl) urea, N- (p-toluenesulfonyl) -N'
-(O-Tolyl) urea, N- (p-toluenesulfonyl) -N '-(m-tolyl) urea, N- (p-toluenesulfonyl) -N'-(p-tolyl) urea, N- (p −
Toluenesulfonyl) -N '-(o-chlorophenyl)
Urea, N- (benzenesulfonyl) -N'-phenylurea, N- (p-chlorobenzenesulfonyl) -N'-phenylurea, 4,4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane, 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, dihydroxydiphenyl 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),
It can be selected from 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone (JP-A-60-208286).

Further, it is preferable that a thermofusible substance (so-called sensitizer) is used in combination in the thermosensitive coloring layer of the present invention. As the sensitizer, a heat-fusible organic compound having a melting point of 50 to 150 ° C. is used, and examples thereof include 1-hydroxy-2-naphthoic acid phenyl ester (JP-A-57-19).
1089), p-benzylbiphenyl (JP-A-60-
82382), benzyl naphthyl ether (Japanese Patent Application Laid-open No. Sho 5)
8-87094), 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-60-5)
6588), 1,5-bis (p-methoxyphenoxy) -3-oxapentane (JP-A-62-181183).
No.), oxalic acid diesters (JP-A-64-1583).
And JP-B-5-62597), 1,4-bis (p-tolyloxy) benzene (JP-A-2-15378).
No. 3), diphenyl sulfone (melting point 124 ° C.), p-toluenesulfonic acid phenyl ester (melting point 96 ° C.), mesitylenesulfonic acid p-tolyl ester (melting point 100-
102 ° C.), 4,4′-diallyloxydiphenyl sulfone (melting point 145 ° C.), 4-ethoxyphenylmethyl sulfone (melting point 91 ° C.), 4,4′-diisopentyloxydiphenyl sulfone (melting point 100 ° C.), 4, 4'-dimethoxydiphenyl sulfone (melting point 130 ° C), 2,2
-Bis (4-benzenesulfonyloxyphenyl) propane (melting point 114 ° C), 2,2-bis (4-methanesulfonyloxyphenyl) propane (melting point 101 ° C), N
-Phenyl-4-methylphenylsulfonamide (melting point 102 ° C), o-chloroacetoacetanilide (melting point 1
03 ° C.), N-benzyl-o-sulfophthalimide and the like.

The thermosensitive coloring 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
It can be selected from the compounds described in JP-A-49385 and JP-A-2-266645.

The heat-sensitive color forming layer of the heat-sensitive recording material of the present invention mainly contains a dye precursor and one or more functional groups represented by the formula (I) of the present invention in the molecule. It contains an organic compound and a binder, and preferably contains a sensitizer. Further, the heat-sensitive color forming layer, if necessary, a conventionally known phenol-based or organic acid-based developer, antioxidant,
UV absorbers or waxes can be included.
Further, it preferably contains organic or inorganic pigments. The binder is used to fix these components to the support.

The content of the above-mentioned leuco dye in the thermosensitive coloring layer is generally preferably 5 to 20% by weight based on the total dry weight of the thermosensitive coloring layer, and the functional group represented by the formula (I) of the present invention is added to the molecule. In general, the content of the one or more color-developing aromatic organic compounds contained therein is preferably 10 to 50% by weight based on the total dry weight of the thermosensitive coloring layer. If this content is less than 10% by weight, the color developing ability may be insufficient, and if it exceeds 50% by weight, the color developing ability is saturated and no particular improvement is seen, which is economically disadvantageous. Sometimes.

When the thermosensitive coloring layer contains an antioxidant or an ultraviolet absorber, its content is preferably 1 to 10% by weight. When a conventionally known phenol-based or organic acid-based color developer or N-arylsulfonylurea derivative is contained, its content is preferably 5 to 40% by weight, and the content of the sensitizer is 10-40% by weight is preferred. When waxes and white pigments are contained in the thermosensitive coloring layer, their contents are 5 to 20% by weight and 10 to 50%, respectively.
It is preferably in% by weight, and the content of 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,
Examples thereof include organic fine powders such as polystyrene resin and the like. However, if a large amount of an alkaline earth metal salt such as calcium carbonate is used, the sensitivity may be lowered. 2 of dry weight
It is preferably 0% by weight or less.

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

Regarding the binder, polyvinyl alcohol having various molecular weights, starch and its derivatives, cellulose derivatives such as methoxycellulose, carboxymethylcellulose, methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester Polymers, acrylic acid amides / acrylic acid esters / methacrylic acid terpolymers, styrene / maleic anhydride copolymers alkaline salts, polyacrylamides, sodium alginates, gelatin, and water-soluble polymeric materials such as 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 thermosensitive recording medium of the present invention is paper (including acidic paper and neutral paper), coated paper having a surface coated with a pigment and / or latex, laminated paper, polyolefin resin. Synthetic paper, made from
You can choose from plastic films.

On at least one surface of such a sheet-like substrate, a coating solution containing a mixture of the above-mentioned required components is applied and dried to form a thermosensitive color forming layer to produce a thermosensitive recording material. The coating amount of the thermosensitive coloring layer is 1 to 1 when the coating liquid layer is dried.
It is preferably 5 g / m ² and particularly preferably ² to 10 g / m ² .

In the heat-sensitive recording material of the present invention, a coating layer such as a protective layer or a printing layer can be further formed on the heat-sensitive color forming layer.

[0038]

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

Synthesis Example 1 1,3-bis (p-toluene)
Rufonylaminocarbonylhydrazinocarbonyl) ben
Synthesis of Zen In a three-necked flask equipped with a thermometer, a reflux condenser, and a dropping funnel, 4.9 g of isophthalic acid dihydrazide and 15
0 ml of acetonitrile was added, and 10.4 g of p-toluenesulfonyl isocyanate was added dropwise from a dropping funnel at room temperature while stirring the mixture with a magnetic stirrer. An exothermic reaction occurred with the dropping. The reaction suspension was refluxed for 1 hour with stirring and cooled,
The reaction mixture was filtered and 14.0 g of 1,3-bis (p-
A white solid of toluenesulfonylaminocarbonylhydrazinocarbonyl) benzene was collected.

When this crystal was analyzed by a differential scanning calorimeter (DSC), an endothermic peak at 159 ° C. which was considered to be the melting point of the compound was observed. By NMR measurement, the obtained compound was identified as the target product. NMR measurement (heavy D
The results are shown below. δ = 2.40 (s, 6H), 7.42 (d, 4H),
7.60 (t, 1H), 7.82 (d, 4H), 7.9
8 (d, 2H), 8.28 (s, 1H), other NH
The peaks that are considered to be due to δ = 8.70 and 10.4
And around 11.2.

Synthesis Example 2 4,4'-bis (p-toluene)
Sulfonylaminocarbonylhydrazinosulfonyl) di
Synthesis of phenyl ether In a three-necked flask equipped with a thermometer, a reflux condenser and a dropping funnel, 7.2 g of 4,4'-oxybis (benzenesulfonylhydrazide) and 300 ml of acetonitrile were placed, and the mixture was magnetically stirred. While stirring, at room temperature, from the dropping funnel, 8.3 g of p
-Toluenesulfonyl isocyanate was added dropwise. An exothermic reaction occurred with the dropping. The reaction suspension was refluxed with stirring for 1 hour, cooled and then the reaction mixture was filtered to give 1
A white solid of 4.3 g of 4,4'-bis (p-toluenesulfonylaminocarbonylhydrazinosulfonyl) diphenyl ether was collected.

When this crystal was analyzed by DSC (Differential Scanning Calorimeter), an exothermic peak at 217 ° C. which was thought to be due to decomposition of the compound was observed. By NMR measurement, the obtained compound was identified as the target product. The results of NMR measurement (in heavy DMSO) are as follows. δ = 2.35 (s, 6H), 7.10 (d, 4H),
7.40 (d, 4H), 7.70 (d, 4H), 7.7
5 (d, 4H), and other peaks that are thought to be due to NH appear at δ = 8.83, 9.76 and 10.9.

Synthesis Example 3 N- (p-toluenesulfonyl)
Aminocarbonyl) -N '-(2-benzothiazoyl)
Synthesis of hydrazine In a three-necked flask equipped with a thermometer, a reflux condenser, and a dropping funnel, 8.3 g of 2-hydrazinobenzothiazole and 150 ml of acetonitrile were placed, and the mixture was stirred with a magnetic stirrer at room temperature. From the dropping funnel, 10.4 g of p-toluenesulfonyl isocyanate was added dropwise. An exothermic reaction occurred with the dropping. The reaction solution was refluxed for 1 hour with stirring, cooled and then the reaction mixture was filtered to give 10.0 g of N- (p-toluenesulfonylaminocarbonyl) -N '-(2-benzothiazoyl) hydrazine as white. The solid was collected.

When this crystal was analyzed by DSC (Differential Scanning Calorimeter), an endothermic peak at 175 ° C. which was considered to be the melting point of the compound was observed. By NMR measurement, the obtained compound was identified as the target product. NMR measurement (heavy D
The results are as follows. δ = 2.40 (s, 3H), 7.10 (t, 1H),
7.30 (t, 1H), 7.42 (d, 2H), 7.4
6 (d, 1H), 7.75 (d, 1H), 7.82
(D, 2H), and other peaks that are thought to be caused by NH appear at δ = 9.15, 9.75, and 11.4.

Synthesis Example 4 N- (p-toluenesulfonyl)
Aminocarbonyl) -N '-(phenylcarbonyl) hi
Synthesis of Drazine In a three-necked flask equipped with a thermometer, a reflux condenser, and a dropping funnel, 5.4 g of benzoylhydrazine and 150
ml of acetonitrile was added, and 8.3 g of p-toluenesulfonyl isocyanate was added dropwise from a dropping funnel at room temperature while stirring the solution with a magnetic stirrer. An exothermic reaction occurred with dropping, and a white solid was precipitated. The reaction solution was refluxed for 1 hour with stirring and cooled, then the reaction mixture was filtered and 12.0 g of N- (p
A white solid of -toluenesulfonylaminocarbonyl) -N '-(phenylcarbonyl) hydrazine was collected.

When this crystal was analyzed by DSC (Differential Scanning Calorimeter), an endothermic peak which appeared to be the melting point of the compound appeared at 199 ° C. By NMR measurement, the obtained compound was identified as the target product. NMR measurement (heavy D
The results are as follows. δ = 2.40 (s, 3H), 7.40 (d, 2H),
7.40-7.60 (m, 3H), 7.80 (d, 2
H), 7.80 (d, 2H), and other peaks that are considered to be caused by N-H are δ = 8.60, 10.26 and 11.
Appeared around 15.

[0047]Synthesis example 5  N- (p-toluenesulfonyl
Aminocarbonyl) -N '-(p-toluenesulfoni
Le) Synthesis of hydrazine A three-necked tube equipped with a thermometer, a reflux condenser, and a dropping funnel.
To the rusco, add 7.5 g of p-toluenesulfonyl hydrazide.
And 100 ml of acetonitrile, and mix
While stirring the liquid with a magnetic stirrer, bring it to room temperature.
Then, from the dropping funnel, 8.3 g of p-toluene sulfone was added.
Diisocyanate was added dropwise. Exothermic reaction starts with dropping
A white solid precipitated. 1 while stirring this reaction solution
After refluxing for hours and cooling, the reaction mixture was filtered,
0 g of N- (p-toluenesulfonylaminocarbonyl)
) -N '-(p-toluenesulfonyl) hydrazine
A white solid was collected.

When this crystal was analyzed by DSC (Differential Scanning Calorimeter), an exothermic peak which appeared to be due to decomposition of the compound appeared at 205 ° C. By NMR measurement, the obtained compound was identified as the target product. The results of NMR measurement (in heavy acetone) are as follows. δ = 2.40 (s, 3H), 2.50 (s, 3H),
7.30 (d, 2H), 7.45 (d, 2H), 7.6
8 (d, 2H), 7.85 (d, 2H), other NH
The peaks believed to be due to δ = 8.30 and 8.60.
And appeared around 9.70.

Example 1 A thermosensitive recording paper was prepared by the following procedure. (1) Dispersion A prepared INGREDIENT AMOUNT (parts) 3- (N-isopentyl -N- ethylamino) - Paint 6-methyl-7-anilinofluoran 20 polyvinyl alcohol 10% solution 10 Water 70 The composition Using a shaker, the powder was pulverized until the average particle size became 1 μm or less.

[0050] (2) Dispersion B prepared INGREDIENT AMOUNT (parts) N-(p-toluenesulfonyl aminocarbonyl) - N '- (phenylcarbonyl) hydrazine 10 diphenylsulfone 10 polyvinyl alcohol 10% solution 10 Water 70 The composition The average particle size is 1μ with a paint shaker
It was pulverized until it became m or less.

(3) Preparation of Pigmented Undercoat Paper 85 parts of calcined clay (trade name Ansilex) in 320 parts of water
40 parts of styrene-butadiene copolymer emulsion (solid content 50%) and 10 parts of
% 50% oxidized starch aqueous solution to prepare a coating solution,
This coating liquid was applied onto a base paper having a basis weight of 48 g / m ² so that the coating amount after drying was 7.0 g / m ² , to prepare a pigment-undercoated paper.

(4) Formation of Thermosensitive Coloring Layer 30 parts of HG clay pigment, 20 parts of 25% zinc stearate dispersion, 30 parts of the above solution A and 200 parts of solution B were added.
A 15% paraffin dispersion liquid and 15 parts of a 10% aqueous polyvinyl alcohol solution were mixed and stirred to prepare a coating liquid. 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.

(5) Super calender treatment The thermal recording paper obtained as described above was treated with a super calender and the surface smoothness was 1000 to 1
It was 400 seconds.

(6) Whiteness measurement and color development test The samples of the above thermal recording paper were measured for whiteness with a Hunter whiteness meter using a blue filter.
Also, for this sample, a color tester THP manufactured by Okura Electric
Using MD, printing voltage 21.7V, printing pulse 1.0ms
Printed under the conditions. The density of this printed color portion was measured with a Macbeth reflection densitometer RD-914 (this is called the original density). Table 1 shows the measured whiteness and the value of the original density.

Example 2 Thermal recording paper was manufactured and tested in the same manner as in Example 1. However, in the preparation of the dispersion liquid B, N- (p-toluenesulfonylaminocarbonyl) -N '-(p-toluene was used instead of N- (p-toluenesulfonylaminocarbonyl) -N'-(phenylcarbonyl) hydrazine. Sulfonyl) hydrazine was used. The test results are shown in Table 1.

Example 3 Thermal recording paper was manufactured and tested in the same manner as in Example 1. However, in preparing the dispersion liquid B, N- (p-toluenesulfonylaminocarbonyl) -N '-(2-benzo was used instead of N- (p-toluenesulfonylaminocarbonyl) -N'-(phenylcarbonyl) hydrazine. Thiazoyl) hydrazine was used. The test results are shown in Table 1.

Comparative Example 1 The same operation as in Example 1 was performed. However, in the preparation of the dispersion liquid B, N- (p-nitrobenzoyl) -p-toluenesulfonamide (melting point: 206 ° C.) was used instead of N- (p-toluenesulfonylaminocarbonyl) -N ′-(phenylcarbonyl) hydrazine. : JP-A-62-19
The compound described in No. 485) was used. The test results are shown in Table 1.

[0058]

[Table 1]

Example 4 Thermal recording paper was manufactured and tested in the same manner as in Example 1. However, in the preparation of the dispersion B, 1,3-bis (p- was used instead of N- (p-toluenesulfonylaminocarbonyl) -N '-(phenylcarbonyl) hydrazine.
Toluenesulfonylaminocarbonylhydrazinocarbonyl) benzene was used, and the following oil resistance and plasticizer resistance tests were conducted in addition to the color development test of Example 1 and (6).

(7) Oil resistance and plasticizer resistance test A predetermined test piece was prepared from the color-developed sample of the color development test (6), and the salad oil or plasticizer ( Dioctyl terephthalate) was applied and left at room temperature for 1 hour, the oil or plasticizer (dioctyl terephthalate) on the surface of the test piece was wiped off, and the residual image density was measured with a Macbeth reflection densitometer, and the image retention rate was calculated according to the following formula. Was calculated. Image preservation ratio (%) = (concentration after oil resistance and plasticizer resistance test) / (original concentration) × 100 Test results (including image preservation ratio value) are shown in Table 2.

Comparative Example 2 The same operation as in Example 4 was performed. However, in the preparation of the dispersion liquid B, N- (o-carboxybenzoyl) -p-toluenesulfonamide (melting point 161 ° C .: special temperature was used instead of 1,3-bis (p-toluenesulfonylaminocarbonylhydrazinocarbonyl) benzene in preparation of the dispersion liquid B. Kaisho 62-19
The compound described in No. 485) was used. The test results are shown in Table 2.

Comparative Example 3 The same operation as in Example 4 was performed. However, in preparing the dispersion liquid B, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) was used instead of 1,3-bis (p-toluenesulfonylaminocarbonylhydrazinocarbonyl) benzene. Table 2 shows the test results
Shown in.

[0063]

[Table 2]

As is clear from Table 1, the novel color developer of the present invention has a higher color developing ability and is superior to the compound (Comparative Example 1) having some similarity in chemical structure. It was confirmed to show whiteness. Further, as is clear from Table 2 above, in the novel developer of the present invention, 2
A color-developed image with a color-developing organic compound having one or more sulfonylsemicarbazide groups is represented by bisphenol A (Comparative Example 3), which is a representative of conventional color-developing agents, and a compound having some chemical structural similarity (Comparative Example 2). It was confirmed that the oil resistance of the image was significantly superior to that of the plasticizer resistance.

[0065]

INDUSTRIAL APPLICABILITY The heat-sensitive recording material of the present invention contains an aromatic compound having one or more functional groups represented by the formula (I) in one molecule as a developer in the heat-sensitive color forming layer. Because of its use, the resulting color image shows high color density and excellent oil and plasticizer resistance.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-2-302750 (JP, A) JP-A-7-25163 (JP, A) JP-A-7-9771 (JP, A) JP-A-6- 255262 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41M 5/28-5/34 CAPLUS (STN) REGISTRY (STN)

Claims (3)

(57) [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): (In the above formula (I), X represents an oxygen atom or a sulfur atom), and at least one type of color-developing organic compound having at least one functional group in the molecule. And a thermal recording medium. 2. The color-developing organic compound is represented by the following general formulas (II) and (III): (However, in the above formulas (II) and (III), R ₁ represents a member selected from a lower alkyl group, an aralkyl group, and an aryl group, and the aromatic ring group constituting the aralkyl group and the aryl group The aromatic ring group may be further substituted with at least one member selected from a lower alkyl group, an alkoxy group, an aryl group, a halogen atom and an acetyl group, and R ₂ is a monobasic carboxylic acid residue or a monobasic organic sulfonic acid. A residue, a heteroaromatic ring having a substituted or unsubstituted aromatic ring portion, an alkyl group, an aralkyl group, and shows a member selected from an aryl group, the aromatic ring group in the aralkyl group, and, The aromatic ring group in the aryl group is further selected from a lower alkyl group, an alkoxy group, an aryl group, a halogen atom, a hydroxyl group, an acetyl group and a carboxyl group. Optionally substituted by at least one member, Y represents a divalent or higher valent organic or inorganic residue, and n represents an integer of 2 or more.). The thermosensitive recording medium according to claim 1. 3. The color-developing organic compound is represented by the following formulas (IV) and (V): Wherein 1,3-bis (p-toluenesulfonylaminocarbonylhydrazinocarbonyl) benzene represented by the formula [m represents an integer of 1 or more] and hydrates thereof. 1. The heat-sensitive recording material according to 1.