JP2015003403A - Thermosensitive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosensitive recording medium which has high recording density, which is excellent in oil resistance and plasticizer resistance of the recording part and excellently resisting surface coloring due to heat in high temperature environment, and further excellently resisting sticking and adhesion of dregs to the head.SOLUTION: In a thermosensitive recording medium which has a thermosensitive recording layer containing at least a leuco dye and a coloring agent on a substrate, the thermosensitive recording medium contains a predetermined diphenyl sulfone cross-linking compound, a predetermined urea-urethane compound and N-[2-(3-phenylureido)phenyl] benzenesulfonamide as the coloring agent. The predetermined urea-urethane compound is preferably contained with a rate of 0.2-5 pts.mass based on 1 pt.mass of the predetermined diphenyl sulfone cross-linking compound.

Description

  The present invention relates to a heat-sensitive recording material utilizing a color development reaction between a leuco dye and a colorant.

  A heat-sensitive recording material is known in which a recording image is obtained by reacting a colorless or light-colored leuco dye and a color former capable of acting as an electron acceptor of the leuco dye with heat to cause color development.

  The fields of use include, for example, cash register sheets and ticket sheets for POS (Point of Sales) systems. With the expansion of the system, the use environment and use methods are diversified, and use under severe conditions is also possible. It is increasing. Furthermore, since it is also used as a receipt in the same application, it is necessary to have good storage stability and sealability for various chemicals such as oil in the recording section, plasticizer, office supplies, and hand cream.

  It is known that in a heat-sensitive recording material provided with a heat-sensitive recording layer mainly composed of a leuco dye and a colorant on a support, the color-development reaction is reversible, so that the color-development image disappears with time. It has been. This decolorization reaction is accelerated in a high temperature and high humidity environment, and further proceeds rapidly by contact with oil, plasticizer, etc., and the recorded image may be decolored until it cannot be read. On the other hand, in order to improve the storability of the recording part, it has been proposed to add an epoxy compound in the heat-sensitive recording layer (see Patent Document 1). However, it has a sufficient effect on oil and plasticizer. Is not obtained.

  In order to solve this problem, it has been proposed to use at least one diphenylsulfone crosslinking compound and at least one specific hydroxydiphenylsulfone derivative in combination as a colorant (see Patent Document 2). However, in the heat-sensitive recording material described in Patent Document 2, the storage stability of the recording portion with respect to oil or plasticizer is improved, but the stability (heat resistant background fogging) of the non-printing portion is insufficient, and sticking. There is a problem that wrinkles are likely to adhere to the thermal head.

  Further, urea urethane compounds such as 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone have been proposed as colorants (see Patent Document 3). However, while the compound described in Patent Document 3 has excellent image storage stability, it is insufficient in sensitivity in applications where high sensitivity is required. Further, the compound described in Patent Document 3 has a remarkable decrease in whiteness (liquid fog) due to the coloration of the coating liquid containing the compound over time, and the background portion of the thermal recording material produced by applying the coating liquid. The coloring (background fogging) becomes remarkable. Furthermore, the coloring of the background portion of the thermal recording material (wet-resistant background fogging) that occurs when the thermal recording material is stored in a high-humidity environment is remarkable. There is a problem that it becomes even more prominent.

  In order to improve the moisture resistance of the thermal recording material using 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, in the presence of a coloring inhibitor such as silicate. It has been proposed to use the dispersion liquid co-dispersed in (1) by heat treatment (see Patent Document 4). However, since the thermal recording material described in Patent Document 4 has low recording sensitivity, the storage of the recording unit with respect to oil and plasticizer in a high-speed printer or a battery-driven handy terminal printer is insufficient.

JP-A-4-286855 Japanese Patent No. 3664840 International Publication WO00 / 14058 Pamphlet International Publication WO2005 / 042263 Pamphlet

  The present invention provides a heat-sensitive recording medium having a high recording density, excellent oil resistance, plasticizer resistance and heat-resistant background fogging in a high temperature environment, and excellent sticking resistance and head resistance. Main purpose.

  As a result of intensive studies in view of the above-described conventional technology, the present inventors have solved the above-described problems. That is, the present invention relates to the following thermal recording material.

  Item 1: In a heat-sensitive recording body having a heat-sensitive recording layer containing at least a leuco dye and a colorant on a support, the diphenylsulfone cross-linking compound represented by the following general formula (1) as the colorant: A heat-sensitive recording material comprising a urea urethane compound represented by the following general formula (2) and N- [2- (3-phenylureido) phenyl] benzenesulfonamide.

（式中、ｎは１〜６の整数を表す。）

(In the formula, n represents an integer of 1 to 6.)

  Item 2: The thermal recording material according to Item 1, wherein the urea urethane compound is contained at a ratio of 0.2 to 5 parts by mass with respect to 1 part by mass of the diphenylsulfone cross-linking compound.

  Item 3: The total content of the diphenylsulfone cross-linking compound and the urea urethane compound is 0.2 to 3 parts by mass with respect to 1 part by mass of the N- [2- (3-phenylureido) phenyl] benzenesulfonamide. Item 3. The thermal recording material according to Item 1 or 2, wherein

  Item 4: The total amount of the colorant contains the diphenylsulfone cross-linking compound and the urea urethane compound in a proportion of 2.5% by mass or more, respectively, and N- [2- (3-phenylureido) Item 4. The heat-sensitive recording material according to any one of Items 1 to 3, comprising phenyl] benzenesulfonamide at a ratio of 15 to 90% by mass.

  Item 5: The thermosensitive recording layer is a stearic acid amide, 2-naphthylbenzyl ether, oxalic acid di-p-chlorobenzyl ester, oxalic acid di-p-methylbenzyl ester, 1,2-di (3- Item 5. The thermal recording material according to any one of Items 1 to 4, comprising at least one selected from the group consisting of (methylphenoxy) ethane, 1,2-diphenoxyethane, and diphenylsulfone.

  Item 6: The heat-sensitive recording material according to any one of Items 1 to 5, wherein the colorant contains a heat-treated urea urea compound in the presence of a basic inorganic pigment.

  Item 7: The heat-sensitive recording material according to Item 6, wherein the basic inorganic pigment is at least one selected from the group consisting of a magnesium compound, an aluminum compound, a calcium compound, a titanium compound, magnesium silicate, magnesium phosphate and talc.

  Item 8: The thermal recording material according to any one of Items 1 to 7, wherein the urea urethane compound is 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone. .

  Item 9: The heat-sensitive recording material according to any one of Items 1 to 8, further comprising an undercoat layer containing plastic hollow particles between the support and the heat-sensitive recording layer.

  Item 10: The heat-sensitive recording material according to any one of Items 1 to 9, further comprising an undercoat layer formed by a blade coating method between the support and the heat-sensitive recording layer.

  Item 11: The heat-sensitive recording material according to any one of Items 1 to 10, wherein at least one layer formed on the support is formed by a curtain coating method.

  Item 12: The heat-sensitive recording material according to any one of Items 1 to 11, wherein the heat-sensitive recording layer is an outermost layer.

  The heat-sensitive recording material of the present invention is a heat-sensitive recording material having a high recording density, excellent oil resistance, plasticizer resistance and heat-resistant background fogging in a high temperature environment, and excellent sticking resistance and head resistance. The main purpose is to provide.

  Although it does not specifically limit as a support body in this invention, For example, neutral or acidic quality paper (neutral paper, acidic paper), a synthetic paper, a transparent or translucent plastic film, a white plastic film etc. are mentioned. . Although the thickness of a support body is not specifically limited, Usually, it is about 20-200 micrometers.

  The support in the present invention is more preferably a neutral paper or acidic paper paper support obtained by making a pulp slurry containing pulp fibers, a filler and a sizing agent. In general, in the case of acidic paper, there is a problem that the color forming material constituting the heat-sensitive recording material reacts with acidic ions on the surface of the paper and easily causes background fogging during a long-term storage period. On the other hand, in the case of neutral paper, while the thermal recording medium is being stored, for example, less than one year, the coloring ability decreases before recording, and after recording, fading occurs and printing occurs. There are problems such as fading, blurring, and in some cases, it is almost invisible. Conventionally, the components to be included in the heat-sensitive recording layer have been properly used depending on the type of paper support, but in the present invention, both neutral paper and acid paper exhibit excellent effects on plasticizer resistance after storage of white paper. In addition, it is possible to obtain a heat-sensitive recording material excellent in storage stability of a blank paper having a latently high recording density while having heat resistance on the background. Although the reason for this is not clear, the performance of the colorant is reduced by forming a salt with the alkali filler contained in the neutral paper while the thermal recording material is stored. On the other hand, it is estimated that N- [2- (3-phenylureido) phenyl] benzenesulfonamide does not cause morphological changes regardless of whether it is neutral paper or acidic paper.

  The type of neutral paper and production method are not particularly limited, but pulp fibers and generally fillers such as calcium carbonate, sizing agents such as alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), etc., and polyamides as fixing agents, A pulp slurry containing acrylic amide, cationic starch and the like can be obtained by paper making. As such neutral paper, the hot water extraction pH (based on JIS P 8133) is preferably in the range of 6.5 to 10, and more preferably in the range of 7.5 to 10. By setting the pH of the neutral paper to 6.5 or more, background fogging during storage of white paper can be effectively suppressed. On the other hand, aggregation of pulp slurry itself can be suppressed by setting pH to 10 or less. Moreover, as long as pH does not become smaller than 6.5, a pH can be adjusted using a sulfuric acid band as needed, and papermaking property can also be improved.

  Kinds of acid paper and production method are not particularly limited, but pulp fibers and fillers such as kaolin, talc, chlorite, rosin soaps such as reinforced rosin soap and reinforced rosin emulsion, alkenyl succinic acid soap, etc. A so-called synthetic sizing agent, etc., and a pulp slurry containing a sulfuric acid band and the like can be obtained by papermaking. Such acidic paper has a hot water extraction pH (based on JIS P 8133) in the range of about 2-6.

  Kinds of pulp fibers used in the present invention, production method and the like are not particularly limited. For example, various high-yield pulps in addition to chemical pulp and SCP such as softwood pulp and hardwood pulp obtained by KP, SP, AP method, and the like, Or a waste paper pulp etc. are mentioned.

  It should be noted that internal additives for papermaking such as dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents can be added to the pulp slurry as appropriate depending on the use of the paper. . Moreover, starch etc. can also be apply | coated in a size press. As the paper machine, a long net paper machine, a twin wire type paper machine, a circular net paper machine, a Yankee dryer paper machine and the like can be used as appropriate.

  The heat-sensitive recording layer in the present invention can contain various known leuco dyes of colorless or light color. Specific examples of such leuco dyes include, for example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl) -3- (4-dimethylamino) Phenyl) -6-dimethylaminophthalide, blue coloring dyes such as fluoran, 3- (N-ethyl-Np-tolyl) amino-7-N-methylanilinofluorane, 3-diethylamino-7-ani Green chromogenic dyes such as linofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3,6-bis (diethylamino) fluorane-γ-anilinolactam, 3-cyclohexylamino-6-chlorofluorane, 3 -Red coloring dyes such as diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3 (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3-diethylamino- 6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-pentyl) amino-6-methyl-7-anilino Fluorane, 3-diethylamino-7- (o-chlorophenylamino) fluorane, 3- (N-ethyl-p-toluidino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-p-toluidino) ) -6-methyl-7- (p-toluidino) fluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino No-6-chloro-7-anilinofluorane, 3-dimethylamino-6-methyl-7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-6 Methyl-7-anilinofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthen-2'-ylamino] ] Black} color developing dye such as phenyl} propane, 3-diethylamino-7- (3′-trifluoromethylphenyl) aminofluorane, 3,3-bis [1- (4-methoxyphenyl) -1- (4- Dimethylaminophenyl) ethylene-2-yl] -4,5,6,7-tetrachlorophthalide, 3,3-bis [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) e Len-2-yl] -4,5,6,7-tetrachlorophthalide, 3-p- (p-dimethylaminoanilino) anilino-6-methyl-7-chlorofluorane, 3-p- (p -Chloroanilino) anilino-6-methyl-7-chlorofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3 '-(6'-dimethylamino) phthalide, etc. And the like. Of course, it is not limited to these, Moreover, 2 or more types can also be used together as needed. Among them, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane, 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, and 3- (N -Ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane is preferably used because of its excellent recording sensitivity and print storage stability. The content ratio of the leuco dye is about 5 to 25% by mass, preferably 7 to 20% by mass, of the total solid content of the heat-sensitive recording layer. By setting the content to 5% by mass or more, the coloring ability can be improved and the printing density can be improved. Heat resistance can be improved by setting it as 25 mass% or less.

  The heat-sensitive recording layer in the present invention is at least one selected from diphenylsulfone cross-linked compounds represented by the general formula (1) as a colorant (hereinafter also referred to as a specific diphenyl sulfone cross-linked compound), the general formula It contains at least one urea urethane compound represented by (2) (hereinafter also referred to as a specific urea urethane compound) and N- [2- (3-phenylureido) phenyl] benzenesulfonamide. As a result, the recording density is high, the oil resistance and plasticizer resistance of the recording area are good, and the heat-resistant background fogging property is excellent in a high-temperature environment. To do. Moreover, the plasticizer resistance after storage of white paper can be improved. The diphenylsulfone cross-linking compound represented by the general formula (1) may be used as a mixture of compounds in which n represents an integer of 1 to 6, and may be used alone or in combination of two or more. May be used.

  Specific examples of the specific urea urethane compound include, for example, 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, 4,4′-bis [(2-methyl-5 -Phenoxycarbonylaminophenyl) ureido] diphenylsulfone, 4- (2-methyl-3-phenoxycarbonylaminophenyl) ureido-4 '-(4-methyl-5-phenoxycarbonylaminophenyl) ureidodiphenylsulfone, and the like. These specific urea urethane compounds can be used singly or in combination of two or more.

  In this invention, it is preferable to contain what heat-processed the specific urea urethane compound represented by the said General formula (2) in presence of a basic inorganic pigment as a colorant. For example, when the heat-sensitive recording layer is formed using a heat-sensitive recording layer coating liquid containing 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, 4,4′- -Bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone was previously heat-treated in the same liquid as the basic inorganic pigment in the temperature range of 50 to 90 ° C., preferably 60 to 80 ° C. It can be blended in the thermal recording layer coating liquid as a dispersion. Thereby, after the thermal recording layer coating liquid is applied and dried to form the thermal recording layer, it is possible to suppress the occurrence of extra color development (background fogging) as the thermal recording body. The treatment time is appropriately adjusted depending on the heating temperature, but it is generally preferable to perform the heat treatment for 2 to 24 hours. The dispersion prior to the heat treatment is prepared by dispersing 4,4′-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone to a predetermined particle size and then mixing a basic inorganic pigment. It can also be obtained by mixing them and then dispersing them to a predetermined particle size.

  The basic inorganic pigment is preferably at least one selected from the group consisting of magnesium compounds, aluminum compounds, calcium compounds, titanium compounds, magnesium oxide, magnesium phosphate, and talc. Of these, magnesium silicate, magnesium phosphate, and talc are preferably used from the viewpoint of the stability of the coating liquid and the coating suitability.

  Although the usage-amount of a basic inorganic pigment is not specifically limited, It is about 0.5-20 mass parts with respect to 100 mass parts of specific urea urethane compounds, Preferably it is about 1-10 mass parts.

  N- [2- (3-phenylureido) phenyl] benzenesulfonamide has a high recording density and a low background fogging property in a high temperature environment, but has a problem that the plasticizer resistance of the recording portion is inferior. When used in combination with a specific diphenylsulfone crosslinking type compound, excellent recording density, oil resistance of the recording area, and plasticizer resistance can be ensured, but there is a problem that sticking resistance and head resistance are lowered. In addition, when used in combination with a specific urea urethane compound, low-energy printing assuming high-speed printers and battery-powered handy terminal printers in recent years has low oil-coloring sensitivity of urea urethane compounds, so that it has sufficient oil resistance and plastic resistance. If the compounding amount is increased in order to improve the color development sensitivity because the agent properties cannot be obtained, there is a problem that the sticking resistance and the head resistance are lowered. On the other hand, by using a specific diphenylsulfone compound and a specific urea urethane compound in combination, the viscosity of the molten component can be reduced, and head wrinkling and sticking can be improved. Furthermore, the specific diphenylsulfone compound and the specific urea urethane compound exhibit a sensitizing effect with each other, so that it is possible to obtain practically sufficient color development sensitivity, and exhibit excellent oil resistance and plasticizer resistance. Is possible. Moreover, in general, when several kinds of colorants are used in combination, the background fog is remarkably deteriorated, whereas the specific diphenylsulfone crosslinking compound, urea urethane compound, and N- [2- (3-phenylureido) phenyl] in the present invention are used. The synergistic effect by the combination of benzenesulfonamide is not only worsening the background fog, but also excellent in that no background fog is generated even under a high temperature environment of 80 ° C.

  The content of the specific urea urethane compound in the thermosensitive recording layer is preferably about 0.2 to 5 parts by mass, more preferably about 0.3 to 3 parts by mass with respect to 1 part by mass of the specific diphenylsulfone crosslinked compound. Preferably, 0.5 to 2 parts by mass is more preferable, and 0.5 to 1.5 parts by mass is particularly preferable. The said effect | action can be effectively expressed by setting it as the range of 0.2-5 mass parts.

  The total content of the specific diphenylsulfone cross-linking compound and the specific urea urethane compound in the heat-sensitive recording layer is 0.2 to 1 part by mass with respect to 1 part by mass of N- [2- (3-phenylureido) phenyl] benzenesulfonamide. About 3 parts by mass is preferable, about 0.3 to 2.5 parts by mass is more preferable, about 0.4 to 2.5 parts by mass is further preferable, about 0.5 to 2 parts by mass is particularly preferable, and 0.9 About ~ 1.5 parts by mass is most preferable. By setting it to 0.2 parts by mass or more, sufficient oil resistance and plasticizer resistance in the recording part can be obtained. On the other hand, when the content is 3 parts by mass or less, the recording density can be improved and the occurrence of background fogging in a high temperature environment can be suppressed.

  In the present invention, of the total amount of the colorant, the diphenylsulfone cross-linking compound and the urea urethane compound are each preferably 2.5% by mass or more, more preferably 4.5% by mass or more, and still more preferably 9%. The N- [2- (3-phenylureido) phenyl] benzenesulfonamide is preferably contained in an amount of 15 to 90% by mass, more preferably 25 to 75% by mass. Moreover, it is preferable to contain the said diphenyl sulfone bridge | crosslinking type compound and the said urea urethane compound in less than 50 mass%, respectively. The total content of these specific colorants is 100% by mass, and adjusting the content within the above range is preferable because the effects of the present invention can be exhibited without regret.

  The total content of the specific diphenylsulfone crosslinking compound and the specific urea urethane compound in the heat-sensitive recording layer is preferably 0.2 to 3.5 parts by mass, and 0.5 to 3 parts by mass with respect to 1 part by mass of the leuco dye. Part is more preferable, 0.7 to 2.5 parts by mass is further preferable, 0.9 to 2.3 parts by mass is particularly preferable, and 1 to 2.2 parts by mass is most preferable. Oil resistance and plasticizer resistance can be improved by setting it as 0.2 mass part or more. When the content is 3.5 parts by mass or less, the recording density and the heat-resistant background fogging property can be improved. The total content of the specific diphenylsulfone cross-linking compound and the specific urea urethane compound is adjusted within the range of the content relative to the N- [2- (3-phenylureido) phenyl] benzenesulfonamide. be able to.

  The content of N- [2- (3-phenylureido) phenyl] benzenesulfonamide in the thermosensitive recording layer is 0.5% with respect to 1 part by mass of leuco dye from the viewpoint of improving the recording density and plasticizer resistance. To 5 parts by mass, preferably 0.8 to 3 parts by mass, more preferably 0.9 to 2.5 parts by mass, particularly preferably 1.0 to 2.3 parts by mass, and 1.0 to 2 parts. .1 part is most preferred. By setting the content to 0.5 parts by mass or more, the recording density and heat-resistant background fogging property can be improved. Oil resistance and plasticizer resistance can be improved by setting it as 5 mass parts or less.

The colorant in the present invention is at least one selected from diphenylsulfone cross-linked compounds represented by the general formula (1), at least one urea urethane compound represented by the general formula (2), and N Although it is-[2- (3-phenylureido) phenyl] benzenesulfonamide, various known materials can be used in combination as long as there is no problem. Specific examples include inorganic acidic substances such as activated clay, attapulgite, colloidal silica, aluminum silicate, 4,4′-isopropylidenediphenol, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1 , 1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 2,4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxydiphenyl sulfide, hydroquinone monobenzyl Ether, 4-hydroxy-4′-benzyloxydiphenylsulfone, benzyl 4-hydroxybenzoate, 4,4′-dihydroxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenylsulfone, bis (3-allyl-4- Hydroxyphenyl) sulfone, Phenolic compounds such as -hydroxy-4'-methyldiphenylsulfone, 4-allyloxy-4'-hydroxydiphenylsulfone, 3,4-dihydroxyphenyl-4'-methylphenylsulfone, N, N'-di-m-chlorophenyl Thiourea compounds such as thiourea, N- (p-toluenesulfonyl) carbamoyl acid p-cumylphenyl ester, N- (p-toluenesulfonyl) carbamoyl acid p-benzyloxyphenyl ester, N- (o-toluoyl) -p - an organic compound having an _-SO 2 NH- bond in the molecule such as toluene sulfonamide, p- chlorobenzoic acid, 4- [2-(p-methoxyphenoxy) ethyloxy] salicylic acid, 4- [3- (p-tolyl Sulfonyl) propyloxy] salicylic acid, 5- [p- (2-p-methoxyphenyl) Noxyethoxy) cumyl] aromatic carboxylic acids such as salicylic acid, and salts of these aromatic carboxylic acids with polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, and further antipyrine of zinc thiocyanate Complex, organic acidic substance such as complex zinc salt of terephthalaldehyde acid and other aromatic carboxylic acid, 4,4′-bis (3-tosylureido) diphenylmethane, 1,5- (3-oxapentylene) -bis ( 3- (3 ′-(p-toluenesulfonyl) ureido) benzoate, 1- (4-butoxycarbonylphenyl) -3-tosylurea, Np-toluenesulfonyl-N′-3- (p-toluenesulfonyloxy) phenyl Urea, N- (p-toluenesulfonyl) -N′-phenylurea, N- (p-tolue Sulfonyl)-N'-p-Toriruurea, 4,4'-bis (3- (tosyl) ureido) diphenylether, 4,4'-bis (3-Toshiruureido) sulfonylurea compounds such as diphenyl sulfone.

  In the heat-sensitive recording material of the present invention, the heat-sensitive recording layer may further contain a preservability improver, a sensitizer, and other various auxiliary agents in addition to the specific colorant and leuco dye.

  In the heat-sensitive recording layer of the present invention, a storability improving agent can be contained. Thereby, the preservability of a recording part can be improved. Examples of the preservability improver include 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 2,2′-ethylidene. Bis (4,6-di-tert-butylphenol), 4,4′-thiobis (2-methyl-6-tert-butylphenol), 4,4′-butylidenebis (6-tert-butyl-m-cresol), 1 -[Α-methyl-α- (4'-hydroxyphenyl) ethyl] -4- [α ', α'-bis (4 "-hydroxyphenyl) ethyl] benzene, 1,1,3-tris (2-methyl -4-hydroxy-5-cyclohexylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, (2,6-dimethyl-4-tertiarybutyl-3-hydroxybenzyl) isocyanurate, 4,4'-thiobis (3-methylphenol), 4,4'-dihydroxy-3,3 ', 5,5 '-Tetrabromodiphenylsulfone, 4,4'-dihydroxy-3,3', 5,5'-tetramethyldiphenylsulfone, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2, Hindered phenol compounds such as 2-bis (4-hydroxy-3,5-dichlorophenyl) propane and 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane; 1,4-diglycidyloxybenzene; 4,4′-diglycidyloxydiphenylsulfone, 4-benzyloxy-4 ′-(2-methylglycidyloxy) diphenylsulfur Hong, diglycidyl terephthalate, cresol novolac epoxy resin, phenol novolac epoxy resin, epoxy compound such as bisphenol A epoxy resin, N, N′-di-2-naphthyl-p-phenylenediamine, 2,2′-methylenebis Examples include sodium salt or polyvalent metal salt of (4,6-di-tert-butylphenyl) phosphate, bis (4-ethyleneiminocarbonylaminophenyl) methane, etc. The content ratio of the preservability improver is improved preservability. In general, the amount is preferably about 1 to 30% by mass, and more preferably about 5 to 20% by mass in the total solid content of the heat-sensitive recording layer.

  The heat-sensitive recording layer in the present invention may contain a sensitizer. Thereby, the recording sensitivity can be increased. Examples of the sensitizer include stearamide, methoxycarbonyl-N-stearic acid benzamyl, N-benzoyl stearamide, N-eicosanoic acid amide, ethylene bis stearic acid amide, behenic acid amide, methylene bis stearic acid amide, N -Methylol stearamide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, 2-naphthylbenzyl ether, m-terphenyl, p-benzyl Biphenyl, oxalic acid di-p-chlorobenzyl ester, oxalic acid di-p-methylbenzyl ester, oxalic acid dibenzyl ester, p-tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether, , 2-di (3-methylphenoxy) ethane, 1,2-di (4-methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ethane, 1,2-di (4-chlorophenoxy) ethane 1,2-diphenoxyethane, 1- (4-methoxyphenoxy) -2- (3-methylphenoxy) ethane, p-methylthiophenylbenzyl ether, 1,4-di (phenylthio) butane, p-acetoluidide, p -Acetophenetide, N-acetoacetyl-p-toluidine, di (β-biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2-phenylethane, diphenylsulfone, etc. . These can be used in combination as long as there is no hindrance.

  In the present invention, stearamide, 2-naphthylbenzyl ether, oxalic acid di-p-chlorobenzyl ester, oxalic acid di-p-methylbenzyl ester, 1,2-di (3-methylphenoxy) ethane is used as a sensitizer. It is preferable to contain at least one selected from the group consisting of 1,2-diphenoxyethane and diphenylsulfone. Since these are excellent in the sensitizing effect of N- [2- (3-phenylureido) phenyl] benzenesulfonamide without impairing the background fogging resistance, they are preferably used. In addition, these sensitizers tend to cause head wrinkling and sticking. However, in the present invention, by using a specific diphenylsulfone compound and a specific urea urethane compound together, the viscosity of the molten component is reduced to reduce head wrinkling and sticking. Therefore, the sensitizing effect can be exhibited without regret.

  The content of the sensitizer is from 1.0 part by mass of N- [2- (3-phenylureido) phenyl] benzenesulfonamide from the viewpoint of effectively increasing recording sensitivity and suppressing background fog resistance. Thus, about 0.6 to 2.5 parts by mass is preferable, and about 0.6 to 1.5 parts by mass is more preferable. Although it may be an amount effective for sensitization, it is usually preferably about 1 to 40% by mass, more preferably about 5 to 25% by mass, and still more preferably of the total solid content of the heat-sensitive recording layer. Is about 8 to 20% by mass.

The heat-sensitive recording layer can be formed by coating and drying on a support using a heat-sensitive recording layer coating solution. The leuco dye, specific colorant, if necessary, sensitizer, preservability improver, etc., either together or separately, for example, with water as a dispersion medium, the average particle size by a stirring / pulverizing machine such as a ball mill, attritor, sand mill, etc. Is finely dispersed so as to be 2 μm or less. The thermal recording layer coating liquid is prepared by mixing and stirring the obtained dispersion liquid with a pigment, a binder, an auxiliary agent and the like. The coating amount of the heat-sensitive recording layer is preferably about 2~12g / ^{m 2} by dry weight, about 3 to 10 g / ^{m 2} is more preferable.

  In the present invention, in order to improve the whiteness of the heat-sensitive recording layer and improve the uniformity of the image, a fine particle pigment having a high whiteness and an average particle size of 10 μm or less can be contained in the heat-sensitive recording layer. Specific examples include, for example, calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcined kaolin, amorphous silica, diatomaceous earth, synthetic aluminum silicate, zinc oxide, titanium oxide, aluminum hydroxide, barium sulfate, surface-treated carbonate. Inorganic pigments such as calcium and silica, and organic pigments such as urea-formalin resin, styrene-methacrylic acid copolymer resin, polystyrene resin and raw starch particles can be used. The content of the pigment is preferably 50% by mass or less, more preferably 30% by mass or less, of an amount that does not decrease the color density, that is, the total solid content of the thermosensitive recording layer.

  Various resins are usually used as binders in the thermal recording layer coating solution. Examples of such binders include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol, and carboxy-modified. Polyvinyl alcohol, diisobutylene-maleic anhydride copolymer salt, styrene-maleic anhydride copolymer salt, ethylene-acrylic acid copolymer salt, styrene-acrylic acid copolymer salt, styrene-butadiene copolymer, urea Examples thereof include resins, melamine resins, amide resins, polyurethane resins and the like. At least one of these is preferably blended in the range of about 5 to 50% by mass, more preferably about 10 to 40% by mass, of the total solid content of the thermosensitive recording layer. When the medium for the thermal recording layer coating liquid is water, the hydrophobic resin may be used in a latex state.

  Examples of the auxiliary agent include sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, fatty acid metal salt and the like, zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, ester wax and the like. Examples include waxes, hydrazide compounds such as adipic acid dihydrazide, water resistant agents such as glyoxal, boric acid, dialdehyde starch, methylol urea, glyoxylate, and epoxy compounds, antifoaming agents, coloring dyes, and fluorescent dyes.

  In the present invention, it is preferable to have an undercoat layer containing plastic hollow particles between the support and the thermosensitive recording layer. Thereby, the recording sensitivity can be further increased. Further, the plastic hollow particles stay on the support to form a uniform undercoat layer, whereby the thickness of the coating layer provided on the undercoat layer can be made uniform, and the barrier property can be improved.

  Examples of the plastic hollow particles include conventionally known particles, for example, particles having a hollow ratio of about 50 to 99% in which the film material is made of an acrylic resin, a styrene resin, a vinylidene chloride resin, or the like. Here, the hollowness is a value obtained by the following formula (d / D) × 100. In the formula, d represents the inner diameter of the organic hollow particles, and D represents the outer diameter of the organic hollow particles. The average particle size of the plastic hollow particles is preferably about 0.5 to 10 μm, more preferably about 1 to 3 μm. By setting the average particle size to 10 μm or less, when the undercoat layer coating solution is applied by a blade coating method, troubles such as streaks and scratches are not caused, and good coating suitability can be obtained.

  The content ratio of the plastic hollow particles can be selected from a wide range, but is generally preferably about 2 to 90% by mass in the total solid content of the undercoat layer. From the viewpoint of improving the color development effect and enhancing the barrier property, the lower limit is more preferably 5% by mass or more, and further preferably 10% by mass or more. On the other hand, from the viewpoint of suppressing wrinkle adhesion to the thermal head, the upper limit is more preferably 80% by mass or less, further preferably 70% by mass or less, particularly preferably 60% by mass or less, and most preferably 50% by mass or less.

  From the viewpoint of improving the effect of suppressing wrinkle adhesion to the thermal head, the undercoat layer preferably contains an oil-absorbing pigment having an oil absorption amount of 70 ml / 100 g or more, particularly about 80 to 150 ml / 100 g. Moreover, a thermally expansible particle can also be contained. Here, the oil absorption is a value determined according to the method described in JIS K 5101.

  Various oil-absorbing pigments can be used, and specific examples include inorganic pigments such as calcined kaolin, amorphous silica, light calcium carbonate, and talc. The average particle diameter of the primary particles of these oil-absorbing pigments is preferably about 0.01 to 5 μm, particularly about 0.02 to 3 μm. The content of the oil-absorbing pigment can be selected from a wide range, but is generally preferably about 2 to 95% by mass and more preferably about 5 to 90% by mass in the total solid content of the undercoat layer.

  When the oil-absorbing inorganic pigment is used in combination with the plastic hollow particles, the oil-absorbing inorganic pigment and the plastic hollow particles are used within the above-mentioned content ratio, and the total amount of the oil-absorbing inorganic pigment and the plastic hollow particles is Of the total solid amount, it is preferably about 5 to 90% by mass, more preferably about 10 to 90% by mass, and still more preferably about 10 to 80% by mass.

The undercoat layer is generally obtained by applying and drying a coating solution for an undercoat layer prepared by mixing and stirring plastic hollow particles, an oil-absorbing pigment, a binder, an auxiliary agent, and the like on a support using water as a medium. It is formed. The coating amount of the undercoat layer is not particularly limited, but is preferably about 3 to 20 g / m ² , more preferably about 5 to 12 g / m ² in terms of dry weight.

  The binder can be appropriately selected from those usable in the heat-sensitive recording layer. In particular, from the viewpoint of improving the coating film strength, oxidized starch, starch-vinyl acetate graft copolymer, polyvinyl alcohol, styrene-butadiene latex and the like are preferable. Although the content rate of a binder can be selected in a wide range, generally about 5-30 mass% is preferable among the total solid content of an undercoat layer, and about 10-20 mass% is more preferable.

  The heat-sensitive recording material of the present invention may be provided with a protective layer on the heat-sensitive recording layer for the purpose of improving the storability of the recorded image with respect to chemicals such as plasticizers and oils, or recording suitability.

The protective layer is, for example, a coating solution for the protective layer prepared by mixing and stirring a binder, a water resistant agent, a pigment, an auxiliary agent, etc., using water as a dispersion medium, and the coating amount is preferably 0.5 wt%. to 15 g / ^{m 2,} more preferably about so that 1.0~8g / ^{m 2} approximately, it is formed by applying and drying a heat-sensitive recording layer.

  Specific examples of the binder include, for example, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy modified polyvinyl alcohol, acetoacetyl modified polyvinyl alcohol, diacetone modified polyvinyl alcohol, silicon modified polyvinyl alcohol, Examples include ionomer type urethane resin latex.

  Examples of the pigment contained in the protective layer include pigments such as kaolin, aluminum hydroxide, light calcium carbonate, and fine particle silica. Of these, kaolin and aluminum hydroxide are preferably used because they have a small decrease in barrier properties against chemicals such as plasticizers and oils and a small decrease in recording density.

  The protective layer may be formed using one or more of a binder and various auxiliary agents without using a pigment, or may be formed using a binder and a pigment in combination. When used in combination, the content ratio of the binder is not particularly limited and can be appropriately selected from a wide range, but in general, about 1 to 95% by mass is preferable in the total solid content of the protective layer, and about 2 to 80% by mass. More preferred. Further, the content ratio of the pigment is not particularly limited and can be appropriately selected from a wide range. Generally, about 1 to 95% by mass is preferable and about 2 to 90% by mass is more preferable in the total solid content of the protective layer. .

  Examples of the auxiliary agent to be included in the protective layer coating liquid include lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax and ester wax, and surfactants such as sodium dioctylsulfosuccinate (dispersant, Humectants), antifoaming agents, water-soluble polyvalent metal salts such as potassium alum and aluminum acetate. In order to further improve the water resistance, water-proofing agents such as glyoxal, boric acid, glyoxylate, dialdehyde starch, hydrazide compound, epoxy compound and the like can be mentioned.

  In the protective layer, microcapsules encapsulating an ultraviolet absorber that is liquid at room temperature, such as 2- (2′-hydroxy-3′-dodecyl-5′-methylphenyl) benzotriazole, are included in the total solid content of the protective layer. When the UV absorber is used in an amount of preferably about 2 to 40% by mass, more preferably about 2 to 35% by mass, and still more preferably about 3 to 30% by mass, the yellow color of the background portion is exposed to light exposure. Discoloration and fading of recorded images can be remarkably suppressed.

  In the present invention, a back layer comprising a pigment and a binder as main components can be provided on the surface of the support opposite to the thermosensitive recording layer, if necessary. As a result, the storage stability can be further improved, and the curl aptitude and the printer runnability can be improved. In addition, various processes in the field of thermal recording material production such as processing the pressure-sensitive adhesive label on the back surface, forming a magnetic recording layer, a coating layer for printing, and further providing a thermal transfer recording layer and an inkjet recording layer, etc. Known techniques can be added as necessary.

  There are no particular limitations on the method of forming the heat-sensitive recording layer and, if necessary, the undercoat layer, the protective layer and the back layer. For example, bar coating, air knife coating, varivar blade coating, pure blade coating, rod blade coating, short dwell coating After coating and drying the undercoat layer coating liquid on the support as necessary by appropriate coating methods such as curtain coating and die coating, apply the thermal recording layer coating liquid and further the protective layer coating liquid on the undercoat layer. And a method such as drying.

  The undercoat layer is preferably a layer formed by a blade coating method. As a result, the heat-sensitive recording layer having a uniform thickness can be formed without the unevenness of the support, and the recording sensitivity can be increased, and the barrier property of the protective layer provided can be improved if necessary. The blade coating method is not limited to a coating method using a blade represented by a bevel type or a vent type, and includes a rod blade method, a bill blade method, and the like.

  In the present invention, it is preferable that at least one layer formed on the support is a layer formed by a curtain coating method. Thereby, a layer having a uniform thickness can be formed, and the recording sensitivity can be increased, and the barrier property against oil, plasticizer, alcohol, etc. can be increased. The curtain coating method is a method in which the coating liquid is allowed to flow and fall freely, and is applied to the support in a non-contact manner, and known methods such as a slide curtain method, a couple curtain method, and a twin curtain method can be employed. There is no particular limitation. In the curtain coating method, a layer having a more uniform thickness can be formed by simultaneous multilayer coating. In simultaneous multi-layer coating, each coating solution is laminated and then applied, and then dried to form each layer. After applying a coating solution that forms the lower layer, the lower surface coating surface is wet without drying. In a state, you may apply | coat the coating liquid which forms an upper layer on a lower layer coating surface, and it may be made to dry after that, and may form each layer. In the present invention, an embodiment in which a heat-sensitive recording layer and a protective layer are simultaneously applied in multiple layers is preferable from the viewpoint of improving barrier properties.

  In the present invention, from the viewpoint of improving the recording sensitivity and improving the image uniformity, after completing the formation of each layer or after completing the formation of all the layers, a super calendar, a soft calendar, etc. It is preferable to perform a smoothing process using a known method.

  In the present invention, in order to further increase the added value of the product, a multicolor thermosensitive recording material can be used. In general, multicolor thermal recording materials are an attempt to utilize the difference in heating temperature or thermal energy, and are generally constructed by sequentially laminating a high-temperature coloring layer and a low-temperature coloring layer that develop colors in different colors on a support. There are two types of erasable type and additive type. These are the methods using microcapsules and multi-color thermal recording media using composite particles composed of organic polymer and leuco dye. There is a manufacturing method.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, “part” and “%” indicate “part by mass” and “% by mass”, respectively.

Example 1
-Preparation of coating solution for undercoat layer Plastic hollow particle dispersion (trade name: Ropaque SN-1055, hollow ratio: 55%, average particle size: 1.0 μm, manufactured by Dow Chemical Co., Ltd., solid content concentration 26.5% by mass) 120 parts, 110 parts of a 50% aqueous dispersion (average particle size: 0.6 μm) of calcined kaolin (trade name: Ansilex, manufactured by BASF), styrene-butadiene latex (trade name: L-1571, Asahi Kasei Chemicals) A composition comprising 20 parts by weight, 50 parts by weight of a solid content, 50 parts of a 10% aqueous solution of oxidized starch, and 20 parts of water was mixed to obtain a coating solution for an undercoat layer.

-Preparation of liquid A (leuco dye dispersion) 3-di (n-butyl) amino-6-methyl-7-anilinofluorane 100 parts, sulfone-modified polyvinyl alcohol (trade name: Goceran L-3266, Nippon Synthetic Chemical A composition comprising 50 parts of a 20% aqueous solution of a 20% aqueous solution of a natural fat and oil, 10 parts of a 5% emulsion of a natural fat-based antifoaming agent (trade name: Nopco 1407H, manufactured by San Nopco), and 90 parts of water is obtained by a laser diffraction particle size using a sand mill A liquid A was obtained by pulverizing until the median diameter was 0.5 μm using a distribution measuring apparatus SALD2200 (manufactured by Shimadzu Corporation).

-Preparation of liquid B (coloring agent dispersion) N- [2- (3-phenylureido) phenyl] benzenesulfonamide 100 parts, sulfone-modified polyvinyl alcohol (trade name: Gocelan L-3266, supra) 20% A composition comprising 50 parts of an aqueous solution, 10 parts of a 5% emulsion of a natural fat and oil-based antifoaming agent (trade name: Nopco 1407H, supra), and 90 parts of water was mixed with a laser diffraction particle size distribution analyzer SALD2200 (Shimadzu Corporation) The liquid B was obtained by pulverizing until the median diameter was 1.0 μm.

-Preparation of liquid C (coloring agent dispersion) 100 parts of the compound represented by the general formula (1) (trade name: D-90, manufactured by Nippon Soda Co., Ltd.), sulfone-modified polyvinyl alcohol (trade name: gold) A composition comprising 50 parts of a 20% aqueous solution of Celan L-3266, supra), 10 parts of a 5% emulsion of a natural fat and oil-based antifoaming agent (trade name: Nopco 1407H, supra), and 90 parts of water was obtained by a sand mill. C liquid was obtained by pulverizing until the median diameter was 1.0 μm using a laser diffraction particle size distribution analyzer SALD2200 (manufactured by Shimadzu Corporation).

-Preparation of liquid D (colorant dispersion) 100 parts of the compound represented by the general formula (2) (trade name: UU, manufactured by Chemipro Kasei Co., Ltd.), sulfone-modified polyvinyl alcohol (trade name: Gocelan L-3266, front A composition comprising 50 parts of a 20% aqueous solution of No. 1), 2 parts of a 5% emulsion of a natural fat and oil-based antifoaming agent (trade name: Nopco 1407H, supra), and 98 parts of water using a sand mill. The liquid D was obtained by pulverizing until the median diameter was 1.0 μm using an apparatus SALD2200 (manufactured by Shimadzu Corporation).

Preparation of liquid E (sensitizer dispersion) 1,2-di (3-methylphenoxy) ethane 100 parts, sulfone-modified polyvinyl alcohol (trade name: Gocelan L-3266, supra) 50 parts aqueous solution, A composition consisting of 2 parts of a 5% emulsion of a natural fat and oil-based antifoaming agent (trade name: Nopco 1407H, supra) and 98 parts of water was subjected to a laser diffraction particle size distribution analyzer SALD2200 (manufactured by Shimadzu Corporation) using a sand mill. The liquid E was obtained by pulverizing until the median diameter became 1.0 μm.

-Preparation of coating solution for heat-sensitive recording layer A part 20 parts, B part 28 parts, C part 18 parts, D part 18 parts, E part 25 parts, aluminum hydroxide (trade name: Hygielite H-42, average particle size 1.0 μm, Showa Denko Co., Ltd.) 15 parts, fine powder amorphous silica (trade name: Mizukasil P-605, average particle diameter 3.0 μm, Mizusawa Chemical Co., Ltd.) 18 parts, starch-vinyl acetate graft copolymer ( 120 parts of 10% aqueous solution of trade name: Petrocoat C-8, manufactured by Nissho Chemical Co., Ltd., 20 parts of 10% aqueous solution of fully saponified polyvinyl alcohol (trade name: GOHSENOL NМ-11, manufactured by Nippon Synthetic Chemical Co., Ltd.), stearin A composition comprising 15 parts of zinc acid dispersion (trade name: Hydrin Z-8-36, solid content concentration 36%, manufactured by Chukyo Yushi Co., Ltd.) and 20 parts of water was mixed to obtain a thermal recording layer coating solution. .

-Preparation of thermosensitive recording material On one side of a high-quality paper (basic paper with hot water extraction pH 5.3) having a basis weight of 53 g / m ² as a support, the weight after drying the coating liquid for the undercoat layer was 5.5 g / The undercoat layer is formed by applying and drying by a blade coating method using a blade coater so as to be m ^2, and the weight after drying the thermal recording layer coating liquid on the undercoat layer is 3.5 g / m ^2. Thus, after applying and drying by a curtain coating method using a slide hopper type curtain coating apparatus, a super calendar process was performed to obtain a heat-sensitive recording material.

Example 2
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, the same as Example 1 except that the amount of liquid C was 6 parts instead of 18 parts and the amount of liquid D was 30 parts instead of 18 parts. A heat-sensitive recording material was obtained.

Example 3
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, the same as Example 1 except that the amount of liquid C was 30 parts instead of 18 parts and the amount of liquid D was 6 parts instead of 18 parts A heat-sensitive recording material was obtained.

Example 4
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, the amount of solution B was changed to 45 parts instead of 28 parts, the amount of solution C was changed to 9 parts instead of 18 parts, and the amount of solution D was changed to 18 parts. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that 9 parts were used instead.

Example 5
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, the amount of B solution was 19 parts instead of 28 parts, the amount of C liquid was 23 parts instead of 18 parts, and the amount of D liquid was 18 parts. A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the content was 23 parts.

-Preparation of liquid F (colorant dispersion) 100 parts of the compound represented by the general formula (2) (trade name: UU, supra), 5 parts of magnesium silicate, sulfone-modified polyvinyl alcohol (trade name: gold) -A composition comprising 50 parts of a 20% aqueous solution of Celan L-3266, supra), 10 parts of a 5% emulsion of a natural fat-based antifoaming agent (trade name: Nopco 1407H, supra), and 90 parts of water by a sand mill. A dispersion was obtained by pulverizing until the median diameter was 1.0 μm using a laser diffraction particle size distribution analyzer SALD2200 (manufactured by Shimadzu Corporation). Further, the dispersion was subjected to a heat treatment at 70 ° C. for 4 hours to obtain a liquid F.

Example 6
A thermosensitive recording material was obtained in the same manner as in Example 1, except that the F solution was used in place of the D solution in the preparation of the thermosensitive recording layer coating solution of Example 1.

Comparative Example 1
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, the liquid B was not used, the amount of the liquid C was 32 parts instead of 18 parts, and the amount of the liquid D was 32 parts instead of 18 parts. Obtained a heat-sensitive recording material in the same manner as in Example 1.

Comparative Example 2
In the preparation of the thermal recording layer coating liquid of Example 1, the thermal recording was performed in the same manner as in Example 1 except that the amount of B liquid was changed to 28 parts instead of 28 parts, and C liquid and D liquid were not used. Got the body.

Comparative Example 3
In the preparation of the heat-sensitive recording layer coating liquid of Example 1, the amount of liquid C was changed to 18 parts instead of 18 parts, and the liquid D was not used. It was.

Comparative Example 4
A thermosensitive recording material was obtained in the same manner as in Example 1 except that in the preparation of the heat-sensitive recording layer coating liquid of Example 1, liquid C was not used and the amount of liquid D was 36 parts instead of 18 parts. It was.

Comparative Example 5
The same procedure as in Example 1 was used except that 4,4′-dihydroxydiphenylsulfone was used instead of N- [2- (3-phenylureido) phenyl] benzenesulfonamide in the preparation of Liquid B of Example 1. A heat-sensitive recording material was obtained.

  The thermosensitive recording material thus obtained was evaluated as follows. The results were as shown in Table 1.

(Recording density)
Using a thermal recording evaluation machine (trade name: TH-PMH, manufactured by Okura Electric Co., Ltd.), each thermal recording body is printed with an applied energy of 0.25 mJ / dot, and the optical properties of the recorded and unrecorded areas (background areas) The density was measured in a visual mode of a reflection densitometer (trade name: Macbeth densitometer RD-918, manufactured by Gretag Macbeth). The larger the numerical value, the higher the density of printing, and the recording portion is preferably 1.20 or more practically. On the other hand, it is preferable that the numerical value of the background portion is smaller. When the value exceeds 0.2, background fogging becomes a problem.

(Heat-resistant)
The optical density of the unrecorded part (background part) after leaving each thermosensitive recording medium before recording for 2 hours in a high temperature environment of 80 ° C. is measured by a reflection densitometer (trade name: Macbeth densitometer RD-918, Gredagg Macbeth Co., Ltd.) ) And the visual mode. The smaller the value, the more preferable.

(Oil resistance)
Salad oil was applied to the surface of the recording part of each thermal recording material developed for recording density measurement, left in an environment of 23 ° C. and 50% RH for 24 hours, and then the surface of the recording part after wiping the surface with gauze was processed. The optical density was measured in the visual mode of a reflection densitometer (trade name: Macbeth densitometer RD-918, manufactured by Gretag Macbeth). Further, the storage ratio of the recording part was obtained by the following formula. After processing, the recording density is preferably 1.0 or more and the storage rate is 60% or more.
Storage rate (%) = (recording density after processing / recording density before processing) × 100

(Plasticizer resistance)
A wrap film (trade name: HiES Soft, manufactured by Nippon Carbide Industries Co., Ltd.) is wrapped on a polycarbonate pipe (40 mmΦ) in a triple layer, and each thermosensitive recording medium colored for recording density measurement is placed on it. Wrapping film is wrapped in three layers, and the optical density of the recording part after being left for 24 hours in an environment of 23 ° C. and 50% RH is measured by a reflection densitometer (trade name: Macbeth densitometer RD-918, Gretag Macbeth Measured in visual mode. Further, the storage ratio of the recording part was obtained by the following formula. After processing, the recording density is preferably 1.0 or more and the storage rate is 60% or more.
Storage rate (%) = (recording density after processing / recording density before processing) × 100

(Sticking resistance)
Using a thermal printer (trade name: Resupli T8, manufactured by SATO), each thermal recording medium is colored with an arbitrary print pattern at 2 inches / sec (density 5A), and the print length and print quality from the start of printing to the end of printing. Were visually observed and evaluated according to the following criteria.
○: No problem in printing length and printing quality.
Δ: There is no problem in the printing length, but the printing quality is slightly inferior due to whiteout printing, but there is no practical problem.
X: There is a practical problem in print quality such that the print length is shorter or longer than the normal length, or there is whitening of the print.

(Head resistance)
Using a thermal printer (trade name: Resupli T8, manufactured by SATO), each thermal recording medium was colored 90 cm at 4 inches / sec (concentration 3A), and the wrinkle adhesion state of the thermal head was visually observed and evaluated according to the following criteria. did.
○: No wrinkle adhesion is observed.
(Triangle | delta): Although wrinkle adhesion is seen slightly, it is a level which does not have a problem practically.
X: Wrinkle adhesion is observed and is a practically problematic level.

  The heat-sensitive recording material of the present invention has a high recording density, good oil resistance and plasticizer resistance of the recording area, and excellent heat-resistant background fogging in a high-temperature environment, and further has anti-sticking and head resistance. Because it is excellent, it is suitable for receipts and ticket forms.

Claims (12)

In a heat-sensitive recording material having a heat-sensitive recording layer containing at least a leuco dye and a colorant on the support, the diphenylsulfone cross-linking compound represented by the following general formula (1), the following general formula, as the colorant A thermosensitive recording material comprising a urea urethane compound represented by (2) and N- [2- (3-phenylureido) phenyl] benzenesulfonamide.

(In the formula, n represents an integer of 1 to 6.)

  The heat-sensitive recording material according to claim 1, wherein the urea urethane compound is contained at a ratio of 0.2 to 5 parts by mass with respect to 1 part by mass of the diphenylsulfone cross-linking compound.   The total content of the diphenylsulfone cross-linking compound and the urea urethane compound is 0.2 to 3 parts by mass with respect to 1 part by mass of the N- [2- (3-phenylureido) phenyl] benzenesulfonamide. The heat-sensitive recording material according to claim 1 or 2.   Of the total amount of the colorant, the diphenylsulfone cross-linking compound and the urea urethane compound are each contained in a proportion of 2.5% by mass or more, and N- [2- (3-phenylureido) phenyl] benzene The heat-sensitive recording material according to any one of claims 1 to 3, comprising a sulfonamide at a ratio of 15 to 90% by mass.   As the sensitizer, the thermosensitive recording layer is stearamide, 2-naphthylbenzyl ether, oxalic acid di-p-chlorobenzyl ester, oxalic acid di-p-methylbenzyl ester, 1,2-di (3-methylphenoxy). The heat-sensitive recording material according to claim 1, comprising at least one selected from the group consisting of ethane, 1,2-diphenoxyethane, and diphenylsulfone.   The heat-sensitive recording material according to claim 1, wherein the colorant contains a heat-treated urea urethane compound in the presence of a basic inorganic pigment.   The heat-sensitive recording material according to claim 6, wherein the basic inorganic pigment is at least one selected from the group consisting of a magnesium compound, an aluminum compound, a calcium compound, a titanium compound, magnesium silicate, magnesium phosphate, and talc.   The thermosensitive recording material according to any one of claims 1 to 7, wherein the urea urethane compound is 4,4'-bis [(4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone.   The thermal recording body according to any one of claims 1 to 8, further comprising an undercoat layer containing hollow plastic particles between the support and the thermal recording layer.   The heat-sensitive recording material according to claim 1, further comprising an undercoat layer formed by a blade coating method between the support and the heat-sensitive recording layer.   The heat-sensitive recording material according to claim 1, wherein at least one layer formed on the support is formed by a curtain coating method.   The heat-sensitive recording material according to claim 1, wherein the heat-sensitive recording layer is an outermost layer.