JP2003191647A - Heat sensitive recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat sensitive recording material excellent in ground whiteness, ground preservability, image preservability and the sealing fixing properties of stamps, seals or the like. <P>SOLUTION: In the heat sensitive recording material having a heat sensitive recording layer including an electron donative normally colorless or light-colored dye precursor and an electron acceptive compound, which develops color in the dye precursor through the reaction under heat therewith and at least one protective layer provided on the heat sensitive recording layer, a diphenylsulfone derivative represented by general formula 1 is included in the heat sensitive recording layer and a porous pigment, the specific surface area measured by the B. E. T. method of which is 100 m<SP>2</SP>/g or more, is included in the protective layer. Further, a porous pigment, the specific surface area measured by the B. E. T. method of which is 100 m<SP>2</SP>/g or more, is included in the heat sensitive recording layer. Furthermore, a diphenylsulfone derivative represented by general formula 2 is included in the heat sensitive recording layer. In addition, an amorphous silica is included in the protective layer and a calcium carbonate is included in the heat sensitive recording layer. <P>COPYRIGHT: (C)2003,JPO

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, and more particularly to a heat-sensitive recording material excellent in background whiteness, background storability, image storability and imprint fixing property such as stamps and stamps.

[0002]

2. Description of the Related Art A heat-sensitive recording material generally comprises a support and a heat-sensitive recording layer containing an electron-donating, usually colorless or pale-colored dye precursor and an electron-accepting developer as main components. By heating with a thermal head, a heating pen, a laser beam or the like, a dye precursor and a developer react instantaneously to obtain a recorded image. JP-B-43-4160 and JP-B-45-14039. It is disclosed in the gazette and the like.
Such a heat-sensitive recording material has the advantages that recording can be obtained with a relatively simple device, that maintenance is easy, and that noise is not generated.Measurement recorders, facsimiles, printers, computer terminals, It is used in a wide range of fields such as labels and ticket vending machines.

Particularly in recent years, such as receipts of gas, water, electricity bills, ATM usage statements of financial institutions, various receipts, financial-related recording sheets, heat-sensitive recording labels or heat-sensitive recording tags for POS systems, etc. Also, thermal recording materials have come to be used.

As the applications and demands of the heat-sensitive recording material are expanded in various ways, there is a possibility that they may come into contact with various chemicals. For example, water-based ink, oil-based ink, highlighter pen, red ink,
Chemical resistance to office supplies such as adhesives and diazo developers, or cosmetics such as hand creams, hair tonics, and emulsions, and resistance to plasticizers contained in vinylidene chloride films and synthetic leather are now required. ing. further,
Thermosensitive recording materials have a problem that discoloration of unprinted parts and discoloration of recorded image parts occur when exposed to sunlight, fluorescent light, etc. for a long time, and it is necessary to improve light resistance. There is.

As a heat-sensitive recording material having high heat response and excellent storage of the background / recorded image, Japanese Patent Publication No. 5-1
Japanese Patent No. 3071 describes that using a benzenesulfonamide derivative as an electron-accepting compound. However, it is difficult to say that this heat-sensitive recording material has practically sufficient thermal response and recorded image storability.

Further, in the heat-sensitive recording material, a protective layer having water resistance and chemical resistance for preventing permeation of water, oil, plasticizer, etc. is formed on the heat-sensitive recording layer for the purpose of improving the storability of recorded images. The method is described in JP-A-48-051644, JP-A-54-3549, and JP-A-54-128.
347, JP-A-58-53484, JP-A-60-31996, JP-A-61-229590, JP-A-62-278086, JP-A-62-
280073, JP-A-1-230681,
It is proposed in Japanese Patent Laid-Open No. 2-274589.

On the other hand, the above-mentioned meter-reading paper and various receipts are often printed with a seal and a stamp.
In addition to the fact that the printed image does not bleed, it is required for the heat-sensitive recording material that the image does not bleed and ink does not adhere to the finger even if the printing portion is rubbed with the finger immediately after the printing. However, when the protective layer is provided, the thermal recording layer is protected from water and chemicals from the outside, but on the other hand, the non-drying ink receptivity of red ink, water-based stamps, oil-based stamps, etc., as well as the absorbability, so-called imprint fixing property, deteriorates. It had the drawback of

In order to eliminate such drawbacks, a method of forming a protective layer in which the types of resin contained, the types of pigment, the oil absorption amount, the particle size and the component ratio thereof are controlled is disclosed in JP-A-61-24.
9789, JP 62-55189, JP 1-222177, JP 1-2221279, JP 1-255588, JP 3-17.
3679, JP-A-3-193387, JP-A-3-227294, JP-A-4-323080, and JP-A-1-301368.

[0009] Further, JP-A-3-190786, JP-A-3-190789, JP-A-3-190791.
Japanese Patent Laid-Open No. 3-190793, Japanese Patent Laid-Open No. 3-1
No. 93485, JP-A-3-193487 and JP-A-3-205181, a water-soluble polymer, silica having an average particle diameter of 2.0 to 5.0 μm, an average particle diameter of 0.5 to
A protective layer containing 2.0 μm of light calcium carbonate and 5.0 to 50.0 mass% of starch particles with respect to the total mass of the protective layer is disclosed in JP-A-3-190790 and JP-A-3-19.
The tear strength of the film formed in Japanese Patent No. 0792 is 20 ° C.
5.0 to 50.% relative to the total mass of the water-soluble polymer, pigment, and protective layer having a relative humidity of 60% and 1 kg / mm or more
A protective layer containing 0% by weight of starch particles has been proposed.

Recently, JP-A-6-166265 discloses a softening point of 150 ° C. or higher and an oil absorption of 150 ml /
The protective layer containing organic fine particles of 100 g or more is disclosed in JP-A-6-234275 and JP-A-6-262853.
And the glass transition temperature is 50.
A protective layer containing an inorganic pigment such as aluminum hydroxide, magnesium hydroxide or heavy magnesium carbonate in an emulsion of a hydrophobic resin having a temperature of not less than 0 ° C. is disclosed in JP-A-7-257029.
In JP-A-8-337059, a protective layer containing a spherical or spheroidal basic magnesium carbonate is stamped with a protective layer containing talc and amorphous silica having an oil absorption of 100 cc / 100 g or more. It has been proposed as a means for improving fixability. Also, JP-A-8-7239
No. 9, JP-A-8-25805, a method of using a water-absorbing urethane polymer for a protective layer, and further, JP-A No. 10-44603, amorphous on a protective layer provided on a heat-sensitive recording layer. A method of providing a stamp ink absorbing layer made of silica, a polyamine-based cationic resin, and polyvinyl alcohol is disclosed.

However, even if these methods are used,
The present situation is that a heat-sensitive recording material having seal imprint fixing property and good recording image storability such as chemical resistance has not yet been obtained.

[0012]

DISCLOSURE OF THE INVENTION The present invention relates to a heat-sensitive recording material, and provides a heat-sensitive recording material excellent in background whiteness, background storability, image storability and imprint fixing property such as stamps and stamps. Intended.

[0013]

DISCLOSURE OF THE INVENTION As a result of intensive studies, the present inventors have invented a heat-sensitive recording material of the present invention which can solve the problems.

That is, a heat-sensitive recording layer containing an electron-donating, usually colorless or light-colored dye precursor on a support, and an electron-accepting compound that reacts upon heating to develop a color of the dye precursor, and the heat-sensitive recording. A heat-sensitive recording material having at least one protective layer on the layer, wherein the heat-sensitive recording layer contains a diphenylsulfone derivative represented by the general formula 1, E. T. Specific surface area measured by the method is 100 m ²
/ G or more and a porous pigment and a water-soluble resin or a water-dispersible resin.

[Chemical 5] [In the formula, R ₇ and R ₈ may be the same or different. They are hydrocarbon radicals,

[Chemical 6] (R9 represents a methylene group or an ethylene group), or

[Chemical 7] (R ₁₀ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms). The hydrocarbon group for R ₇ and R ₈ has 1 to 12 carbon atoms and may contain an unsaturated bond or an ether bond. R _{1 to} R ₆ each independently represent a halogen atom, an alkyl group or an alkenyl group. Also, a, b,
c, d, e, and f each represent an integer of 0 to 4, and when 2 or more, R _{1 to} R ₆ may be the same or different. g is 0
Represents an integer of 10]

Further, the thermosensitive recording material is characterized in that the compounding ratio of the porous pigment is 40% by mass to 80% by mass with respect to the total solid content in the protective layer.

Further, in the thermosensitive recording layer, B. E. T. To the law
Therefore, the measured specific surface area is 100m ²/ G or more
A heat-sensitive recording material containing a porous pigment.
It

Further, the heat-sensitive recording material is characterized in that the heat-sensitive recording layer contains a diphenylsulfone derivative represented by the general formula 2.

[Chemical 8] (In the formula, R ₁₁ and R ₁₂ may be the same or different substituents, and each of them may be a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, an alkenyl group, an aralkyl group, an aryl group, an alkoxyl group. Group or a phenyl sulfone group, and h and i each represent an integer of 1 to 4.)

Further, the heat-sensitive recording material is characterized in that the protective layer contains amorphous silica and the heat-sensitive recording layer contains calcium carbonate.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The content of the present invention will be described more specifically. The heat-sensitive recording material of the present invention, a heat-sensitive recording layer containing an electron-donating usually colorless to light-colored dye precursor on an support and an electron-accepting compound that reacts when heated to develop the dye precursor, A heat-sensitive recording material having at least one protective layer on the heat-sensitive recording layer.

The protective layer of the heat-sensitive recording material of the present invention comprises B.I.
E. T. Specific surface area measured by the method is 100 m ² / g
It is composed of the above porous pigment and a water-soluble resin or a water-dispersible resin.

By including such a porous pigment in the protective layer, the non-drying ink acceptability and absorbability of red ink, water-based stamps, oil-based stamps, etc., that is, the so-called imprint fixing property, is significantly improved, and the stamping property of the stamp is improved. Immediately after imprinting, it is possible to solve the problem that the image bleeds or the stamp ink adheres to the finger when the imprinted portion is rubbed with a finger or the like.

The porous pigment used in the protective layer includes
Examples include porous amorphous silica, porous calcium carbonate, porous magnesium carbonate, and porous alumina (pseudo-boehmite, δ-alumina).

The water-soluble resin or water-dispersible resin used in the protective layer is appropriately selected from conventionally known water-soluble polymers or water-dispersible resins. That is, as the water-soluble resin, for example, polyvinyl alcohol, modified polyvinyl alcohol, starch or a derivative thereof, cellulose derivative such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, polyvinyl pyrrolidone, polyacrylamide, acrylamide / acrylic acid ester copolymer. , Acrylamide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer ,
Alkali salt of isobutylene / maleic anhydride copolymer,
Sodium alginate, gelatin, casein, acid-neutralized products of chitosan and the like can be used.

Examples of the water-dispersible resin include styrene / butadiene copolymers, acrylonitrile / butadiene copolymers, methyl acrylate / butadiene copolymers, acrylonitrile / butadiene / styrene terpolymers,
Polyvinyl acetate, vinyl acetate / acrylic acid ester copolymer, ethylene / vinyl acetate copolymer, polyacrylic acid ester, styrene / acrylic acid ester copolymer, polyurethane and the like can be used.

Among these resins, when a water-dispersible resin, which is a hydrophobic resin, is used, it becomes easy to impart appropriate water resistance to the protective layer, and as a result, immediately after imprinting with a stamp, stamp or the like. When the surface is rubbed, it is possible to avoid troubles such as damage to the protective layer and difficulty in reading the print. Therefore, a water-dispersible resin that is a hydrophobic resin is preferable.

The protective layer has a higher fatty acid metal salt such as zinc stearate and calcium stearate, a higher fatty acid amide such as stearic acid amide, and paraffin for the purpose of improving recording runnability such as prevention of head wear and sticking.
Lubricants such as polyethylene wax, polyethylene oxide and castor wax are added as necessary.

The coating amount of the protective layer in the present invention is 0.3.
It is preferably in the range of 10 to 10 g / m ² . 0.3 g
If it is less than / m ² , sufficient image storability, recorded image storability, and imprint fixing property cannot be obtained. On the other hand, when it exceeds 10 g / m ² , it becomes difficult to obtain good thermal response.

The content of the porous pigment used in the protective layer is preferably 40% by mass to 80% by mass based on the total solid content in the protective layer. When the content of the porous pigment is less than 40% by mass, it is difficult to obtain sufficient imprint fixing property.
On the contrary, if it exceeds 80% by mass, it becomes difficult to obtain a good thermal response.

When amorphous silica is selected as the porous pigment used in the protective layer of the heat-sensitive recording material of the present invention and calcium carbonate is selected as the pigment used in the heat-sensitive recording layer,
This is preferable because the background preservation property can be improved without deteriorating the thermal response and the imprint fixing property of the heat-sensitive recording material. Such amorphous silica is microporous and amorphous fine particles in which a three-dimensional structure of SiO ₂ is formed by gelling silicic acid, and has a pore size of about 10 to 2000 angstrom.

As such amorphous silica, commercially available products can be preferably used. For example, Mizukasil P-52 can be used.
6, Mizukasil P-801, Mizukasil NP-8, Mizukasil P-802, Mizukasil P-802Y, Mizukasil C-212, Mizukasil P-73, Mizukasil P-7
8A, Mizukasil P-78F, Mizukasil P-87, Mizukasil P-705, Mizukasil P-707, Mizukasil P-707D, Mizukasil P-709, Mizukasil C
-402, Mizukasil C-484 (all manufactured by Mizusawa Chemical Co., Ltd.),
Tokuseal U, Tokuseal UR, Tokuseal GU, Tokuseal AL-1, Tokuseal GU-N, Tokuseal N,
Tokuseal NR, Tokuseal PR, Fineseal E-
50, Fine seal T-32, Fine seal X-3
7, fine seal X-70, fine seal RX-7
0, Fine seal A, Fine seal B (above, made by Tokuyama), Carplex 80, Carplex 67
(Above, manufactured by Shionogi Pharmaceutical Co., Ltd.), Sylysia 250N, Sylysia 310, Sylysia 320, Sylysia 350, Sylysia 430, Sylysia 431, Sylysia 44.
0, Sylysia 450, Sylysia 470, Sylysia 530, Sylysia 540, Sylysia 550 (above,
Fuji Silysia Chemical) and the like.

The heat-sensitive recording layer of the heat-sensitive recording material of the present invention comprises
As pigments, diatomaceous earth, talc, kaolin, calcined kaolin, ground calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, titanium dioxide, barium sulfate, zinc sulfate, amorphous Inorganic pigments such as high quality silica, amorphous calcium silicate and colloidal silica, organic pigments such as melamine resin filler, urea-formalin resin filler, polyethylene powder and nylon powder can be used. E. T. It is preferable to select a porous pigment having a specific surface area of 100 m ² / g or more as measured by the method since the imprint fixing property can be improved without deteriorating the thermal response of the heat-sensitive recording layer.

The diphenyl sulfone derivative represented by the general formula 1 is used as the electron-accepting compound for coloring the dye precursor constituting the heat-sensitive recording layer of the heat-sensitive recording material of the present invention.

By using the diphenyl sulfone derivative represented by the general formula 1 as the electron-accepting compound, it is possible to obtain a heat-sensitive recording material having high background whiteness and background preservability, and further excellent image preservability.

The diphenyl sulfone derivative used in the present invention is disclosed in JP-A-10-862 and JP-A-10-2996.
It can be represented by the general formula 1 described in JP-A-9.

In the general formula 1, the alkyl group or alkenyl group of R _{1 to} R ₆ is a C _{1 to} C ₆ alkyl group or a C 2 to C 4 alkenyl group, specifically, a methyl group,
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-
Examples thereof include a butenyl group, a 3-butenyl group, a 1,3-butanedienyl group and a 2-methyl-2-propenyl group, and a halogen atom represents chlorine, bromine, fluorine or iodine.

Specific examples of the groups represented by R ₇ and R ₈ include the following. 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, 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, 2-hydroxy-2-butyltrimethylene group and the like can be mentioned.

In the general formula 1, when g is 0, the compounds described in JP-A No. 7-149713 can be exemplified by the following. (1-1) 1,1-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] methane (1-2) 1,2-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] ethane (1-3 ) 1,3-Bis [4- (4-hydroxyphenylsulfonyl) phenoxy] propane (1-4) 1,4-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] butane (1-5) 1,5 -Bis [4- (4-hydroxyphenylsulfonyl) phenoxy] pentane (1-6) 1,6-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] hexane (1-7) α, α'-bis [ 4- (4-hydroxyphenylsulfonyl) phenoxy] -o-xylene (1-8) α, α′-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] m-Xylene (1-9) α, α'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] -p-xylene (1-10) 1,3-bis [4- (4-hydroxyphenylsulfonyl)) Phenoxy] -2-hydroxypropane (1-11) 2,2'-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] diethyl ether (1-12) 4,4'-bis [4- (4-hydroxy) Phenylsulfonyl) phenoxy] dibutyl ether (1-13) 1,2-bis [4- (4-hydroxyphenylsulfonyl) phenoxy] ethylene (1-14) 1,4-bis [4- (4-hydroxyphenylsulfonyl)) Phenoxy] -2-butene

In the general formula 1, when g is not 0, the following compounds can be specifically exemplified.

(2-1) 4,4'-bis [4- {4-
(4-Hydroxyphenylsulfonyl) phenoxy}-
2-trans-butenyloxy] diphenylsulfone (2-2) 4,4'-bis [4- {4- (4-hydroxyphenylsulfonyl) phenoxy} butyloxy] diphenylsulfone (2-3) 4,4'-bis [ 3- {4- (4-hydroxyphenylsulfonyl) phenoxy} propyloxy]
Diphenylsulfone (2-4) 4,4'-bis [2- {4- (4-hydroxyphenylsulfonyl) phenoxy} ethyloxy] diphenylsulfone (2-5) 4- [4- {4- (4-hydroxyphenyl) Sulfonyl) phenoxy} butyloxy] -4 '-[3
-{4- (4-Hydroxyphenylsulfonyl) phenoxy} propyloxy] diphenylsulfone (2-6) 4- [4- {4- (4-hydroxyphenylsulfonyl) phenoxy} butyloxy] -4 '-[2
-{4- (4-Hydroxyphenylsulfonyl) phenoxy} ethyloxy] diphenylsulfone (2-7) 4- [3- {4- (4-hydroxyphenylsulfonyl) phenoxy} propyloxy] -4'-
[2- {4- (4-hydroxyphenylsulfonyl) phenoxy} ethyloxy] diphenylsulfone (2-8) 4,4'-bis [5- {4- (4-hydroxyphenylsulfonyl) phenoxy} pentyloxy]
Diphenyl sulfone (2-9) 4,4'-bis [6- {4- (4-hydroxyphenylsulfonyl) phenoxy} hexyloxy]
Diphenyl sulfone (2-10) 4- [4- {4- (4-hydroxyphenylsulfonyl) phenoxy} -2-trans-butenyloxy] -4 '-[4- {4- (4-hydroxyphenylsulfonyl) phenoxy} Butyloxy] diphenylsulfone (2-11) 4- [4- {4- (4-hydroxyphenylsulfonyl) phenoxy} -2-trans-butenyloxy] -4 '-[3- {4- (4-hydroxyphenylsulfonyl)] Phenoxy} propyloxy] diphenylsulfone (2-12) 4- [4- {4- (4-hydroxyphenylsulfonyl) phenoxy} -2-trans-butenyloxy] -4 '-[2- {4- (4-hydroxy (Phenylsulfonyl) phenoxy} ethyloxy] diphenylsulfone (2-13) 1,4-bi [4- [4- [4- {4-
(4-Hydroxyphenylsulfonyl) phenoxy}-
2-trans-butenyloxy] phenylsulfonyl]
Phenoxy] -cis-2-butene (2-14) 1,4-bis [4- [4- [4- {4-
(4-Hydroxyphenylsulfonyl) phenoxy}-
2-trans-butenyloxy] phenylsulfonyl]
Phenoxy] -trans-2-butene (2-15) 4,4'-bis [4- {4- (2-hydroxyphenylsulfonyl) phenoxy} butyloxy]
Diphenyl sulfone (2-16) 4,4'-bis [4- {2- (4-hydroxyphenylsulfonyl) phenoxy} butyloxy]
Diphenylsulfone (2-17) 4,4'-bis [2- [2- {4- (4-
Hydroxyphenylsulfonyl) phenoxy} ethyleneoxy] ethoxy] diphenylsulfone

(2-18) 4,4'-bis {4- (4-
Hydroxyphenylsulfonyl) phenyl-1,4-phenylenebismethyleneoxy} diphenylsulfone (2-19) 4,4′-bis {4- (4-hydroxyphenylsulfonyl) phenyl-1,3-phenylenebismethyleneoxy} diphenyl Sulfone (2-20) 4,4'-bis {4- (4-hydroxyphenylsulfonyl) phenyl-1,2-phenylene bismethyleneoxy} diphenyl sulfone

(2-21) 2,2'-bis [4- [4-
[2- [2- {4- (4-hydroxyphenylsulfonyl) phenoxy} ethyleneoxy] ethoxy] phenylsulfonyl] phenoxy] diethyl ether

(2-22) α, α'-bis [4- [4-
{4- (4-Hydroxyphenylsulfonyl) phenyl} -1,4-phenylenebismethyleneoxyphenylsulfonyl] phenoxy] -p-xylene (2-23) α, α'-bis [4- [4- {4- (4-
Hydroxyphenylsulfonyl) phenyl} -1,3-
Phenylene bismethyleneoxyphenylsulfonyl] phenoxy] -m-xylene (2-24) α, α′-bis [4- [4- {4- (4-
Hydroxyphenylsulfonyl) phenyl} -1,2-
Phenylene bismethyleneoxyphenylsulfonyl] phenoxy] -o-xylene

(2-25) 2,4'-bis [2- [2-
{2- (4-Hydroxyphenylsulfonyl) phenoxy} ethyleneoxy] ethoxy] diphenylsulfone (2-26) 2,4'-bis [2- [2- {4- (2-
Hydroxyphenylsulfonyl) phenoxy} ethyleneoxy] ethoxy] diphenylsulfone (2-27) 4,4'-bis [2- [2- {3,5-dimethyl-4- (3,5-dimethyl-4-hydroxyphenyl) (Sulfonyl) phenoxy} ethyleneoxy] ethoxy] diphenylsulfone (2-28) 4,4'-bis [2- [2- {3-allyl-4- (3-allyl-4-hydroxyphenylsulfonyl) phenoxy} ethyleneoxy ] Ethoxy] diphenyl sulfone

(2-29) 4,4'-bis {3,5-dimethyl-4- (3,5-dimethyl-4-hydroxyphenylsulfonyl) phenyl-1,4-phenylenebismethyleneoxy} diphenylsulfone ( 2-30) 4,4'-bis {3,5-dimethyl-4-
(3,5-Dimethyl-4-hydroxyphenylsulfonyl) phenyl-1,3-phenylenebismethyleneoxy} diphenylsulfone (2-31) 4,4'-bis {3,5-dimethyl-4-
(3,5-Dimethyl-4-hydroxyphenylsulfonyl) phenyl-1,2-phenylenebismethyleneoxy} diphenylsulfone (2-32) 4,4'-bis {3-allyl-4- (3-
Allyl-4-hydroxyphenylsulfonyl) -1,4
-Phenylenebismethyleneoxy} diphenylsulfone (2-33) 4,4'-bis {3-allyl-4- (3-
Allyl-4-hydroxyphenylsulfonyl) -1,3
-Phenylenebismethyleneoxy} diphenylsulfone (2-34) 4,4'-bis {3-allyl-4- (3-
Allyl-4-hydroxyphenylsulfonyl) -1,2
-Phenylene bismethyleneoxy} diphenyl sulfone

(2-35) 4,4'-bis [4- (4-
Hydroxyphenylsulfonyl) phenoxy} -2-hydroxypropyloxy] diphenylsulfone (2-36) 1,3-bis [4- [4- {4- (4-hydroxyphenylsulfonyl) phenoxy-2-hydroxypropyloxy} phenyl Sulfonyl] phenoxy] -2-hydroxypropane

The diphenyl sulfone derivative represented by the general formula 1 used in the heat-sensitive recording layer of the heat-sensitive recording material of the present invention is used in the system of the heat-sensitive recording material, and at least one diphenyl sulfone in the case of g of 0 in the general formula 1 is used. Derivatives may be added, and at least one derivative when g is 1 to 10 may be added, and at least one diphenylsulfone derivative and g when g is 0 may be added.
In the case of 1 to 10, at least one or more combined additives may be added.

The heat-sensitive recording material of the present invention is characterized by containing a diphenylsulfone derivative represented by the general formula 1 as an electron-accepting compound, but other electron-accepting compounds may be used as long as the desired effects of the present invention are not impaired. It is also possible to use one or more types of compound in combination. The electron-accepting compound that can be used in combination is typically represented by an acidic substance used in a pressure-sensitive recording material or a heat-sensitive recording material, but is not limited thereto. Examples thereof include phenol derivatives, aromatic carboxylic acid derivatives, N, N′-diarylthiourea derivatives, arylsulfonylurea derivatives, polyvalent metal salts such as zinc salts of organic compounds, and benzenesulfonamide derivatives.

Particularly, when the diphenylsulfone derivative represented by the general formula 1 and the diphenylsulfone derivative represented by the general formula 2 are used in combination as the electron-accepting compound, the whiteness of the background, the storability of the background, and the image storability are impaired. It is preferable because the thermal responsiveness can be improved.

Specific examples of the diphenyl sulfone derivative include 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-n-propoxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfone, 2, 4'-dihydroxydiphenyl sulfone, 4-hydroxydiphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxy-4'-methoxydiphenyl sulfone, 4-hydroxy-4'-ethoxydiphenyl sulfone, 4-hydroxy- 4'-n-butoxydiphenyl sulfone, 4-hydroxy-4'-benzyloxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, bis (3,5-dibromo-4-hydroxyphenyl) sulfone, bis (3,5-di Lolo-4-hydroxyphenyl) sulfone, 3,4-dihydroxydiphenylsulfone, 3,4-dihydroxy-4′-methyldiphenylsulfone, 3,4,4′-trihydroxydiphenylsulfone, 3,4,3 ′, 4 ′ -Tetrahydroxydiphenyl sulfone, 2,3,4-trihydroxydiphenyl sulfone, 3-phenylsulfonyl-4-hydroxydiphenyl sulfone, 2,4-bis (phenylsulfonyl)
Examples thereof include phenol, but the diphenyl sulfone derivative according to the present invention is not limited thereto. If necessary, they may be used alone or in combination of two or more.

The electron-donating, usually colorless or light-colored dye precursor that constitutes the heat-sensitive recording layer of the heat-sensitive recording material of the present invention is typified by pressure-sensitive recording materials and those generally used in heat-sensitive recording materials. However, it is not particularly limited.

Specific examples of dye precursors include (1)
Triarylmethane compound: 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-
Dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p- Dimethylaminophenyl)-
3- (2-phenylindol-3-yl) phthalide,
3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide,
3,3-bis (2-phenylindol-3-yl)-
5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6
-Dimethylaminophthalide, etc.

(2) Diphenylmethane compound: 4,
4'-bis (dimethylaminophenyl) benzhydryl benzyl ether, N-chlorophenyl leuco auramine, N-2,4,5-trichlorophenyl leuco auramine, etc.,

(3) Xanthene compound: Rhodamine B
Anilinolactam, Rhodamine B-p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7-phenylfluorane, 3-diethylamino -7-Chlorofluorane, 3
-Diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3-dibutylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-7-
(2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-
Dipentylamino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tolyl) amino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilino Fluoran, 3- (N-ethyl-N
-Tolyl) amino-6-methyl-7-phenethylfluorane, 3-diethylamino-7- (4-nitroanilino) fluorane, 3-dibutylamino-6-methyl-7.
-Anilinofluorane, 3- (N-methyl-N-propyl) amino-6-methyl-7-anilinofluorane, 3
-(N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- ( N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluorane, 3
-Diethylamino-6-methyl-7- (3-trifluoromethylanilino) fluorane and the like,

(4) Thiazine compounds: benzoyl leuco methylene blue, p-nitrobenzoyl leuco methylene blue, etc.

(5) Spiro compounds: 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran,
Examples thereof include 3,3′-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3-methoxybenzo) spiropyran, and 3-propylspirobenzopyran. Further, these dye precursors can be used alone or in combination of two or more, if necessary.

The heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention may contain a heat-fusible substance in order to improve its thermal response. In this case, 60 ℃ ~ 180
Those having a melting point of ℃ are preferred, especially 80 ℃ ~ 140 ℃
Those having a melting point of are more preferably used.

Specifically, stearic acid amide, N-hydroxymethylstearic acid amide, N-stearyl stearic acid amide, ethylenebisstearic acid amide,
N-stearyl urea, benzyl-2-naphthyl ether, m-terphenyl, 4-benzyl biphenyl, 2,
2′-bis (4-methoxyphenoxy) diethyl ether, α, α′-diphenoxyxylene, bis (4-methoxyphenyl) ether, diphenyl adipate, dibenzyl oxalate, di (4-methylbenzyl ester) oxalate,
Oxalic acid di (4-chlorobenzyl) ester, dimethyl terephthalate, dibenzyl terephthalate, benzenesulfonic acid phenyl ester, bis (4-allyloxyphenyl) sulfone, 1,2-di (3-methylphenoxy) ethane, 1,2 Examples include known heat-fusible substances such as -diphenoxyethane, 4-acetylacetophenone, acetoacetic acid anilides, and fatty acid anilides. These compounds may be used alone or in combination of two or more. Further, in order to obtain sufficient thermal response, it is preferable that the heat-fusible substance accounts for 5 to 50 mass% of the total solid content of the heat-sensitive recording layer.

The heat-sensitive recording layer constituting the heat-sensitive recording material of the present invention is prepared by mixing each aqueous dispersion obtained by finely pulverizing each color-forming component with a resin, coating the composition on a support, and drying. can get. The thermal recording layer may have a single layer structure or a multilayer structure.

As the resin used in the heat-sensitive recording layer, various resins used in ordinary coating can be used.

Specifically, starches, hydroxymethyl cellulose, methyl cellulose, ethyl cellulose,
Carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinylpyrrolidone, polyacrylamide, acrylamide / acrylic acid ester copolymer,
Acrylamide / acrylic acid ester / methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer , A water-soluble resin such as an alkali salt of isobutylene / maleic anhydride copolymer, and a styrene / butadiene copolymer, an acrylonitrile / butadiene copolymer,
Methyl acrylate / butadiene copolymer, acrylonitrile / butadiene / styrene terpolymer, polyvinyl acetate, vinyl acetate / acrylic ester copolymer, ethylene / vinyl acetate copolymer, polyacrylic ester,
Examples thereof include, but are not limited to, water-dispersible resins such as styrene / acrylic acid ester copolymer and polyurethane.

In the heat-sensitive recording layer, higher fatty acid metal salts such as zinc stearate and calcium stearate, higher fatty acid amides such as stearic acid amide, paraffin,
Includes lubricants such as polyethylene wax, polyethylene oxide, and castor wax, UV absorbers such as benzophenone-based and benzotriazole-based for the purpose of improving light resistance, and anionic and nonionic high-molecular weight agents as dispersing / wetting agents. Surfactants, fluorescent dyes, defoaming agents and the like are added as necessary.

The coating amount of the heat-sensitive recording layer is usually 0.1 to 2.0 g / m ^{2 in} terms of the coating amount of the dye precursor. 0.1
When the amount is less than g / m ² , sufficient recording density cannot be obtained, and when the amount is more than 2.0 g / m ² , the coloring sensitivity is not improved, which is disadvantageous in cost. Is.

Paper is mainly used as the support in the present invention. In addition to paper, various woven fabrics, non-woven fabrics, synthetic resin films, synthetic resin laminated papers, synthetic papers, metal sheets,
A vapor-deposited sheet or a composite sheet obtained by combining these by laminating or the like can be arbitrarily used according to the purpose.

In the heat-sensitive recording material of the present invention, one or more undercoat layers composed of a single layer or a plurality of layers of pigments or resins can be provided between the support and the heat-sensitive recording layer, if desired. When the thermal recording material of the present invention is provided with an undercoat layer, the coating amount of the undercoat layer is preferably 1 to 30 g / m ² , and 3 to 20 g.
/ M ² is more preferable.

As the pigment for the undercoat layer, calcined kaolin is generally used, but other than that, diatomaceous earth, talc, kaolin, ground calcium carbonate, precipitated calcium carbonate, magnesium carbonate, zinc oxide, aluminum oxide. , Aluminum hydroxide, magnesium hydroxide,
Use inorganic pigments such as titanium dioxide, barium sulfate, zinc sulfate, amorphous silica, amorphous calcium silicate, colloidal silica, organic pigments such as melamine resin filler, urea-formalin resin filler, polyethylene powder and nylon powder. You can

As the resin for the undercoat layer, various water-soluble resins or water-dispersible resins used in ordinary coating can be used. For example, starches, hydroxymethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium alginate, polyvinylpyrrolidone, polyacrylamide, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / Methacrylic acid terpolymer, alkali salt of polyacrylic acid, alkali salt of polymaleic acid, alkali salt of styrene / maleic anhydride copolymer, alkali salt of ethylene / maleic anhydride copolymer, isobutylene / maleic anhydride Water-soluble resin such as alkali salt of copolymer, and styrene /
Butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, acrylonitrile / butadiene / styrene terpolymer, polyvinyl acetate, vinyl acetate / acrylic acid ester copolymer, ethylene / vinyl acetate Examples thereof include copolymers, polyacrylic acid esters, styrene / acrylic acid ester copolymers, and water-dispersible resins such as polyurethane.

The method for forming the heat-sensitive recording layer, the protective layer or the undercoat layer is not particularly limited, and the heat-sensitive recording layer, the protective layer or the undercoat layer can be formed according to a conventionally known technique. As a specific example, the coating liquid is applied by a method such as air knife coating, rod blade coating, bar coating, blade coating, gravure coating, curtain coating, and E bar coating, and heat-sensitive by drying. A recording layer, a protective layer or an undercoat layer can be formed. Also, planographic, letterpress, flexo, gravure,
Each layer may be formed by various printing machines such as a screen and a hot melt method.

If necessary, after coating the undercoat layer,
After coating the heat-sensitive recording layer or after coating the protective layer, supercalendering treatment can be applied to improve the image quality.

[0069]

EXAMPLES Next, the present invention will be described in more detail by way of examples. However, it is not limited to these.
The parts and% shown below are based on mass, and the coating amount is an absolute dry coating amount.

Example 1 Preparation of coating liquid for undercoat layer Baked kaolin [trade name: Ansilex, oil absorption 90 ml
/ 100 g, manufactured by Engelhard Co., Ltd.] 100 parts, a composition comprising 24 parts of a styrene / butadiene-based latex having a solid content of 50% and 200 parts of water was mixed and stirred to obtain a coating liquid for the undercoat layer.

<Dispersion A> 200 g of 3-dibutylamino-6-methyl-7-anilinofluorane was added to 200 g of a 10% sulfo group-modified polyvinyl alcohol aqueous solution and 60 g of water.
Disperse in 0 g of the mixture and use a bead mill to obtain an average particle size of 1
The dispersion A was obtained by pulverizing to a size of μm.

<Dispersion B>2,2'-bis {4- (4-
Hydroxyphenylsulfonyl) phenoxy} diethyl ether 100 g and 4,4′-bis [2- [2- {4
-(4-Hydroxyphenylsulfonyl) phenoxy}
Ethyleneoxy] ethoxy] diphenyl sulfone 100
g was dispersed in a mixture of 200 g of a 10% sulfonic acid group-modified polyvinyl alcohol aqueous solution and 600 g of water, and pulverized with a bead mill until the average particle size became 0.7 μm to obtain a dispersion B.

<Dispersion C> 200 g of benzyl-2-naphthyl ether was dispersed in a mixture of 200 g of a 10% sulfo group-modified polyvinyl alcohol aqueous solution and 600 g of water,
Dispersion C was obtained by pulverizing with a bead mill until the average particle size became 1 μm.

<Dispersion D> 200 g of calcium carbonate was dispersed in 800 g of a 0.2% sodium polyacrylate aqueous solution and stirred for 10 minutes with a homomixer to obtain a dispersion E.

Preparation of coating liquid for heat-sensitive recording layer Using the above dispersion liquid, the respective materials were mixed in the proportions shown below, and added water was added so that the concentration of the heat-sensitive coating liquid was 17%, and the mixture was sufficiently stirred. To prepare a heat-sensitive recording layer coating liquid.

[0076] Dispersion A 30 parts Dispersion B 70 parts Dispersion C 70 parts Dispersion D 10 parts 40% zinc stearate dispersion 4 parts 30% paraffin wax dispersion 6 parts 10% silicon modified polyvinyl alcohol aqueous solution 15 parts 20% acrylic emulsion 20 parts

<Dispersion 1> 120 g of amorphous silica having a specific surface area of 350 m ² / g (trade name: Mizukasil P-78A, manufactured by Mizusawa Chemical Industry Co., Ltd.) was added to 880 g of a 0.2% sodium polyacrylate aqueous solution. Disperse and use a homomixer 1
The mixture was stirred for 0 minutes to obtain dispersion 1.

Preparation of Protective Layer Coating Liquid Using the above dispersion liquid, the respective materials were mixed in the proportions shown below, and added water was added so that the protective layer coating liquid concentration was 9% aqueous solution, and the mixture was thoroughly stirred. To prepare a protective layer coating liquid.

[0079] Dispersion 1 100 parts 20% acrylic emulsion 40 parts 40% zinc stearate dispersion 5 parts

[0080] on one side of the thermal recording quality neutral paper making basis weight of 70 g / m ² of material, solid coating amount is 9 g / m ² of the undercoat layer coating liquid, solid heat-sensitive recording layer coating composition min The amount of smear is 0.6g in terms of the amount of dye precursor applied.
/ M ² and the solid content of the protective layer coating solution is 1 g / m ² so that the undercoat layer, the heat-sensitive recording layer and the protective layer are formed and dried by calendering. The material was made.

Example 2 <Dispersion liquid 2> 120 g of amorphous silica having a specific surface area of 125 m ² / g (trade name: Mizukasil P-801, manufactured by Mizusawa Chemical Industry Co., Ltd.) is 0.2% aqueous solution of sodium polyacrylate salt. It was dispersed in 880 g and stirred with a homomixer for 10 minutes to obtain a dispersion liquid 2.

Preparation of Thermosensitive Recording Material A thermosensitive recording material was prepared in the same manner as in Example 1 except that Dispersion Liquid 2 was used instead of Dispersion Liquid 1 in the preparation of the protective layer coating liquid in Example 1.

Example 3 Preparation of Thermal Recording Material In the preparation of the coating liquid for protective layer of Example 1, 10 of the dispersion liquid 1 was prepared.
0 part to 50 parts, 40% of 20% acrylic emulsion
A thermosensitive recording material was prepared in the same manner as in Example 1 except that the parts were changed to 70 parts.

Example 4 Preparation of Thermal Recording Material In the preparation of the coating liquid for protective layer of Example 1, 10 of the dispersion liquid 1 was prepared.
0 part to 150 parts, 4% of 20% acrylic emulsion
A heat-sensitive recording material was produced in the same manner as in Example 1 except that 0 part was changed to 10 parts.

Example 5 <Dispersion E> ²⁰⁰ g of amorphous silica having a specific surface area of 125 m ² / g (trade name: Mizukasil P-526, manufactured by Mizusawa Chemical Industry Co., Ltd.) is 0.2% aqueous solution of sodium polyacrylate salt. Dispersion in 800 g and stirring with a homomixer for 10 minutes gave dispersion E.

Preparation of Thermosensitive Recording Material A thermosensitive recording material was prepared in the same manner as in Example 1 except that Dispersion E was used instead of Dispersion D in the preparation of the thermosensitive recording layer coating liquid of Example 1.

Example 6 <Dispersion F> 200 g of 2,4′-dihydroxydiphenyl sulfone was dispersed in a mixture of 200 g of a 10% sulfo group-modified polyvinyl alcohol aqueous solution and 600 g of water, and the average particle diameter was adjusted to 0.7 μm with a bead mill. It was pulverized until it became a dispersion H.

Preparation of Thermosensitive Recording Material Thermal recording was carried out in the same manner as in Example 1 except that in the preparation of the coating liquid for the thermosensitive recording layer of Example 1, 70 parts of Dispersion B was added to 50 parts and 20 parts of Dispersion F was added. The material was made.

Example 7 <Dispersion G> 200 g of aluminum hydroxide was dispersed in 800 g of a 0.5% sodium polyacrylate aqueous solution,
Dispersion liquid F was obtained by stirring with a homomixer for 10 minutes.

Preparation of Thermosensitive Recording Material A thermosensitive recording material was prepared in the same manner as in Example 1 except that Dispersion G was used instead of Dispersion D in the preparation of the thermosensitive recording layer coating liquid of Example 1.

Comparative Example 1 <Dispersion H> 200 g of N- (2-hydroxyphenyl) -p-toluenesulfonamide was dispersed in a mixture of 200 g of a 10% sulfo group-modified polyvinyl alcohol aqueous solution and 600 g of water, and the average particle size was measured using a bead mill. Diameter is 0.7 μm
It was pulverized until it became a dispersion liquid G.

Preparation of heat-sensitive recording material Dispersion B7 was used in the preparation of the heat-sensitive recording layer coating liquid of Example 7.
A thermal recording material was prepared in the same manner as in Example 7 except that 70 parts of Dispersion H was used instead of 0 part.

Comparative Example 2 Preparation of Thermosensitive Recording Material Dispersion B7 was used in the preparation of the coating liquid for the thermal recording layer of Example 7.
A thermosensitive recording material was prepared in the same manner as in Example 7, except that 70 parts of Dispersion F was used instead of 0 part.

Comparative Example 3 <Dispersion Liquid 3> Amorphous silica having a specific surface area of 55 m ² / g [trade name: Mizukasil P-527, manufactured by Mizusawa Chemical Industry]
120 g was dispersed in 880 g of a 0.2% sodium polyacrylic acid salt aqueous solution and stirred for 10 minutes with a homomixer,
Dispersion 3 was obtained.

Preparation of heat-sensitive recording material A heat-sensitive recording material was prepared in the same manner as in Example 7 except that Dispersion 3 was used in place of Dispersion 1 in the preparation of the protective layer coating liquid of Example 7.

Comparative Example 4 Preparation of Thermosensitive Recording Material A thermosensitive recording material was prepared in the same manner as Comparative Example 1 except that Dispersion 3 was used instead of Dispersion 1 in the preparation of the protective layer coating liquid of Comparative Example 1. .

Comparative Example 5 Preparation of Thermosensitive Recording Material A thermal recording material was prepared in the same manner as Comparative Example 2 except that Dispersion 3 was used instead of Dispersion 1 in the preparation of the protective layer coating liquid of Comparative Example 2. .

Examples 1 to 7 and Comparative Examples 1 to 5 were subjected to the following evaluations. The results are shown in Tables 1 and 2.

(1) Thermal response The obtained thermal recording material was printed using a facsimile tester TH-PMD manufactured by Okura Electric. Dot density 8 dots /
mm, using a thermal head with a head resistance of 1681Ω,
Power was supplied with a head voltage of 21 V and a print pulse width of 1.0 ms. The print density was measured with a Macbeth RD-918 type reflection densitometer.

(2) Imprint fixing property A stamp ink [trade name: on the surface of the obtained heat-sensitive recording material]
HG-1 Shachihata Industrial Co., Ltd.] was stamped with a rubber stamp, and immediately after stamping, the stamped portion was rubbed with a finger, and the degree of bleeding of the stamp ink was evaluated on a scale of five. The evaluation criteria are as follows. 1: Almost no ink bleeding is observed 2: Ink is slightly bleeding, but the marking part is completely readable 3: Some ink bleeding is recognized, but marking part is legible 4: Ink bleeding Many of them are unreadable on a part of the marking part. 5: Mark bleeding is remarkable and the marking part is completely unreadable.

(3) Imprinting Water resistance Stamp ink [Product name:
HG-1 Shachihata industry]
After 0 minute, one drop of water was dropped on the printing surface, and the surface was rubbed with a finger, and the degree of remaining stamp ink was evaluated on a scale of five. The evaluation criteria are as follows. 1: The ink remains almost completely 2: The ink is slightly detached, but the marking part is completely legible 3: Part of the ink is detached, but the marking part is legible 4: Ink A large amount of ink is detached and part of the imprinted part is unreadable 5: Marked detachment of ink makes the imprinted part completely unreadable

(4) Heat resistance A recorded image printed with a pulse width of 1.0 msec used in the evaluation of heat response and an unprinted background were exposed under a condition of 60 ° C. for 24 hours.
The density after storage for a period of time was measured with a Macbeth RD-918 type reflection densitometer. In addition, the residual rate of the image area% [(optical density of image area after heating / optical density of image area before heating) × 100] was determined from the optical density of the image area before and after heating. The higher the residual rate%, the better the heat-resistant image storability, and the lower the background density, the less the background fogging, and the better the heat-resistant background storability.

(5) Moisture and heat resistance A recorded image printed with a pulse width of 1.0 msec used in the evaluation of thermal response and an unprinted background were stored for 24 hours under the conditions of 40 ° C. and 90% RH, and the density was measured. Macbeth RD-9
It measured with the 18 type reflection densitometer. In addition, the residual rate of the image area% [(optical density of image area after application of wet heat / optical density of image area before application of heat) × 100] was determined from the optical density of the image area before and after applying wet heat. The larger the residual rate% is, the better the heat and humidity image storability is. The lower the background density is, the less the fog is on the background, and the better the heat and humidity resistant storability is.

(6) Plasticizer resistance A soft vinyl chloride sheet was brought into close contact with a printed image printed with a pulse width of 1.0 msec used for evaluation of thermal response and a non-printed background, and stored at room temperature for 72 hours. The subsequent density was measured with a Macbeth RD-918 type reflection densitometer. Further, the residual rate of the image area% [(optical density of image area after processing / optical density of image area before processing) × 100] was determined from the optical density of the image area before and after the treatment. The larger the residual rate%, the better the plasticizer image storability. The lower the background density, the less the background fogging and the better the plasticizer storability on the background.

(7) Lightfastness The recorded image used in the evaluation of thermal responsiveness, printed with a pulse width of 1.0 msec, and the density of an unprinted background after being exposed to direct sunlight for 5 days were Macbeth RD-918 type. It was measured with a reflection densitometer. Further, the residual rate of the image area% [(optical density of image area after processing / optical density of image area before processing) × 100] was determined from the optical density of the image area before and after the treatment. The larger the residual rate%, the better the light-resistant image storability, and the lower the background density, the less the background fog and the better the light-resistant background storability.

(8) After immersing the heat-sensitive recording material printed with a pulse width of 1.0 msec used for evaluation of water-resistant thermal response in tap water at 20 ° C. for 24 hours, the density of the printed image was Macbeth RD-918 type. It was measured with a reflection densitometer. Further, the residual rate of the image area% [(optical density of image area after processing / optical density of image area before processing) × 100] was determined from the optical density of the image area before and after the treatment. The larger the residual rate% is, the more excellent the water resistant image storability is.

[0107]

[Table 1]

[0108]

[Table 2]

As is clear from Tables 1 and 2, Examples 1 to 7 have higher background preservability than Comparative Examples 1 and 2 or Comparative Examples 4 and 5. This is because the heat-sensitive recording layer contains the diphenyl sulfone derivative represented by the general formula 1.

Examples 1 to 4 and 6 are higher in skin preservability than Examples 5 and 7. This is because the heat sensitive recording layer contains calcium carbonate and the protective layer contains amorphous silica.

Examples 1 to 7 have higher imprint fixing property and imprint water resistance than Comparative Examples 3 to 5. This has a specific surface area of 100
This is due to the fact that the protective layer contains a pigment having m ² / g or more.

In Examples 1 and 2 or Examples 4 to 7, the imprint fixing property and the imprint water resistance are higher than those of Example 3. this is,
The content of the porous pigment is 40 with respect to the total solid content in the protective layer.
This is because it is higher than the mass%.

Examples 1 to 3 or Examples 5 to 7 have higher thermal responsiveness than Example 4. This is because the content of the porous pigment is less than 80% by mass based on the total solid content in the protective layer.

[0114]

[Table 3]

As is clear from Tables 1 to 3, Example 5
In comparison with Examples 1 to 4 or Examples 6 to 7, the imprint fixing property and imprint water resistance are higher, and the background and the image storability are those of Example 1.
Is almost equivalent to This has a specific surface area of 100 m ² / g
This is because the above-described pigment is contained in the heat-sensitive recording layer.

Example 6 is higher in thermal response than Examples 1 to 5 or Example 7, and the background, image storability, imprint fixing property and imprint water resistance are almost the same as in Example 1. This is because the thermosensitive recording layer contains the diphenyl sulfone derivative represented by the general formula 2.

Examples 1 to 7 have higher image storability than Comparative Examples 1 to 2 or Comparative Examples 4 to 5. This is because the heat-sensitive recording layer contains the diphenyl sulfone derivative represented by the general formula 1.

[0118]

As is apparent from Tables 1 to 3, the support contains an electron-donating, usually colorless or light-colored dye precursor and an electron-accepting compound which reacts with heating to develop the dye precursor. A heat-sensitive recording material having a heat-sensitive recording layer and a protective layer of at least one layer on the heat-sensitive recording layer, wherein the heat-sensitive recording layer contains the diphenyl sulfone derivative represented by the general formula 1, E. T. A heat-sensitive recording material excellent in background whiteness, background storability, image storability, and imprint fixing property such as stamps and imprints by containing a porous pigment having a specific surface area of 100 m ² / g or more measured by a method It turns out that Further, it is understood that the compounding ratio of the porous pigment in the protective layer is preferably within the range of the present invention.

In the thermosensitive recording layer, B. E. T. It can be seen that, by containing the porous pigment having a specific surface area of 100 m ² / g or more measured by the method, a heat-sensitive recording material having more excellent imprint fixing property and imprint water resistance can be obtained.

It can be seen that by incorporating the diphenylsulfone derivative represented by the general formula 2 in the heat-sensitive recording layer, a heat-sensitive recording material having more excellent thermal responsiveness can be obtained.

By containing amorphous silica in the protective layer and calcium carbonate in the heat-sensitive recording layer,
It can be seen that a heat-sensitive recording material having more excellent background preservability can be obtained.

Claims (5)

[Claims] 1. A heat-sensitive recording layer comprising an electron-donating, usually colorless or light-colored dye precursor on a support, and an electron-accepting compound which reacts when heated to develop the dye precursor, and the heat-sensitive recording. A thermosensitive recording material having at least one protective layer on the layer, wherein the thermosensitive recording layer contains a diphenylsulfone derivative represented by the general formula 1,
E. T. Specific surface area measured by the method is 100 m ² / g
A heat-sensitive recording material comprising the above porous pigment and a water-soluble resin or a water-dispersible resin. [Chemical 1] [In the formula, R ₇ and R ₈ may be the same or different. They are hydrocarbon radicals, (R ₉ represents a methylene group or an ethylene group), or (R ₁₀ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms). The hydrocarbon group for R ₇ and R ₈ has 1 to 12 carbon atoms and may contain an unsaturated bond or an ether bond. R _{1 to} R ₆ each independently represent a halogen atom, an alkyl group or an alkenyl group. Also, a, b,
c, d, e, and f each represent an integer of 0 to 4, and when 2 or more, R _{1 to} R ₆ may be the same or different. g is 0
Represents an integer of 10] 2. The heat-sensitive recording material according to claim 1, wherein the content of the porous pigment is 40% by mass to 80% by mass based on the total solid content in the protective layer. 3. The thermosensitive recording layer comprising B. E. T. The heat-sensitive recording material according to claim 1 or 2, which contains a porous pigment having a specific surface area of 100 m ² / g or more measured by the method. 4. The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording layer contains a diphenylsulfone derivative represented by the general formula 2. [Chemical 4] (In the formula, R ₁₁ and R ₁₂ may be the same or different substituents, and each of them may be a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, an alkenyl group, an aralkyl group, an aryl group, an alkoxyl group. Group or a phenyl sulfone group, and h and i each represent an integer of 1 to 4.) 5. The heat-sensitive recording material according to claim 1, wherein the protective layer contains amorphous silica and the heat-sensitive recording layer contains calcium carbonate.