JP2012056184A - Heat-sensitive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-sensitive recording medium which has sufficient color developing sensitivity, and has sufficient printing runnability (sticking resistance and head-dreg adhesion resistance).SOLUTION: Regarding the heat-sensitive recording medium in which the surface of a support is provided with a heat-sensitive recording layer containing an colorless or light-colored electron-donating leuco dye and an electron-accepting developer, the outermost surface layer contains a phosphoric ester compound. Excellent water resistance and water blocking resistance are specifically manifested when the outermost surface layer is a protective layer, and further, the protective layer has a specified constitution.

Description

The present invention relates to a heat-sensitive recording material excellent in printing runability (stick resistance, head residue resistance) and color development sensitivity.

In general, a heat-sensitive recording material is usually a colorless or light-colored electron-donating leuco dye and an electron-accepting developer such as a phenolic compound, each of which is ground and dispersed into fine particles, and then mixed together to form a binder, a pigment, A coating solution obtained by adding a sensitivity improver (sensitizer), a lubricant and other auxiliary agents is applied to a support such as paper, synthetic paper, film, plastic, etc. Color is generated by an instantaneous chemical reaction by heating with a hot stamp, a thermal pen, laser light or the like, and a recorded image is obtained.
Thermal recording media are widely used in facsimiles, computer terminal printers, automatic ticket vending machines, measuring recorders, etc., and as their uses diversify, high levels of image stability and blank section stability are required. It has been. However, since the electron-donating leuco dye and the electron-accepting developer contained in the heat-sensitive recording layer are easily dissolved in various solvents, this heat-sensitive recording material can be used for inks such as water-based ink pens and oil-based ink pens, adhesives, and the like. When touched, there is a problem that the white paper portion easily develops color or fades when a chemical such as a plasticizer adheres to the recorded image. In order to eliminate such drawbacks, Patent Documents 1 and 2 disclose a technique in which a protective layer mainly composed of a pigment and a resin is provided on a heat-sensitive recording layer.
In recent years, applications such as handy terminal paper for outdoor measurement and delivery slips have rapidly expanded due to the advantages of no noise during recording, relatively inexpensive equipment, compactness, and easy maintenance. Running properties (stick resistance (stick: print defect due to fusion of thermal printer head and paper), head residue resistance) are required. For the purpose of imparting such a quality to a heat-sensitive recording material, Patent Document 3 discloses a technique for blending a surface layer with a lubricant having an average particle diameter of 1 to 20 μm typified by a fatty acid metal salt.

Patent Document 1: JP-A-48-30437 Patent Document 2: JP-A-48-31958 Patent Document 3: JP-A-2005-288850

However, in recent years, environmentally friendly printers have been energy-saving and printers have been improved to improve printing performance, and higher color development sensitivity and printing runnability (stick resistance, head residue resistance) are required. . Accordingly, an object of the present invention is to provide a thermal recording material having sufficient color development sensitivity and printing runnability.

As a result of intensive studies, the present inventors have solved the above problem by including a phosphoric ester compound in the outermost layer of the thermal recording body provided with a thermal recording layer containing a dye and a developer on the support. As a result, the present invention has been completed.
That is, the present invention is a heat-sensitive recording material provided with a heat-sensitive recording layer containing a colorless or light-colored electron-donating leuco dye and an electron-accepting developer on a support, and a phosphoric acid ester compound on the outermost layer. Is a heat-sensitive recording material.

The heat-sensitive recording material of the present invention has good printing runnability (stick resistance, head residue resistance) and sufficient color development sensitivity.

The reason why the heat-sensitive recording material of the present invention has sufficient print running properties (stick resistance, head residue resistance) and color development sensitivity is not clear, but is presumed as follows. When the phosphate ester compound is dissolved by application of heat, it is arranged on the surface and develops peelability. The phosphoric acid ester compound blended in the outermost layer of the heat-sensitive recording material is arranged on the surface of the recording material by the heat of the printer head, and good printing runnability is obtained. In addition, unlike the lubricants typified by fatty acid metal salts, specifically zinc stearate and calcium stearate, phosphate ester compounds do not reduce the smoothness of the surface. Will improve.
Examples of the phosphate ester compound used in the present invention include monocaproyl phosphate, monooctyl phosphate, monocapryl phosphate, monolauryl phosphate, monomyristyl phosphate, monocetyl phosphate, mono Stearyl phosphate ester, tetraethylene glycol mononeopentyl ether monophosphate ester, triethylene glycol monotridecyl ether monophosphate ester, tetraethylene glycol monolauryl ether monophosphate ester, diethylene glycol monostearyl ether monophosphate ester, dicaproyl phosphorus Acid ester, dioctyl phosphate ester, dicapryl phosphate ester, dilauryl phosphate ester, dimyristyl phosphate ester, dicetyl phosphate ester Tellurium, distearyl phosphate, diphosphate of tetraethylene glycol mononeopentyl ether, diphosphate of triethylene glycol monotridecyl ether, diphosphate of tetraethylene glycol monolauryl ether, diphosphate of diethylene glycol monostearyl ether Examples include esters such as “Separ 328”, “Separ 365”, “Separ 380”, “Separ 440”, “Separ 441”, “Separ 517”, “Separ 521”, “ It is available as “Separ M835” (above, trade name).

As a compounding quantity of the phosphoric acid ester compound used by this invention, Preferably it is 0.2-20 weight part (henceforth, a weight part is solid content conversion) with respect to 100 weight part of coating layer total solid content of the outermost layer. And more preferably 0.2 to 15 parts by weight. When the amount of the phosphate ester compound is less than 0.2 parts by weight, good stick resistance cannot be obtained, and when it exceeds 15 parts by weight, the color development sensitivity and the head residue adhesion may be deteriorated.

In the present invention, a protective layer can be provided on the thermosensitive recording layer. As a protective layer in this invention, the structure of the protective layer 1 shown below or the protective layer 2 is preferable.

[Protective layer 1]
The protective layer contains epichlorohydrin resin and polyamine / amide resin together with carboxy-modified polyvinyl alcohol. When the protective layer of the present invention has a constitution of the protective layer 1, that is, a constitution containing an epichlorohydrin resin and a polyamine / amide resin together with carboxy-modified polyvinyl alcohol, excellent water resistance and water blocking resistance are specific. Expressed in When epichlorohydrin resin or polyamine / amide resin is used alone together with carboxy-modified polyvinyl alcohol, or epichlorohydrin resin or polyamine / amide resin with carboxy-modified polyvinyl alcohol and other general crosslinking agents. For example, when the epichlorohydrin-based resin or polyamine / amide-based resin and glyoxal are used in combination, the above effect is exhibited, but the configuration of the protective layer 1 is preferable because the above effect is remarkably exhibited.

The carboxy-modified polyvinyl alcohol used in the constitution of the protective layer 1 is obtained by introducing a carboxyl group for the purpose of enhancing the reactivity to polyvinyl alcohol, which is a water-soluble polymer. Polyvinyl alcohol and fumaric acid, phthalic anhydride, melitto anhydride Reaction products with polycarboxylic acids such as acid and itaconic anhydride, or esterification products of these reaction products, and ethylene such as vinyl acetate and maleic acid, fumaric acid, itaconic acid, crotonic acid, acrylic acid, and methacrylic acid It is obtained as a saponified product of a copolymer with an unsaturated dicarboxylic acid. Specific examples of the production method include the method exemplified in JP-A-53-91995.

The epichlorohydrin resin used in the configuration of the protective layer 1 is a resin characterized by containing an epoxy group in the molecule. For example, a polyamide epichlorohydrin resin, a polyamine epichlorohydrin resin, etc. can be mentioned, These can be used alone or in combination. Moreover, as an amine which exists in the principal chain of an epichlorohydrin-type resin, the thing from primary to quaternary can be used, and there is no restriction | limiting in particular. Furthermore, since the water resistance is good, the degree of cationization and the molecular weight are preferably a cationization degree of 5 meq / g · Solid (measured value at pH 7) and a molecular weight of 500,000 or more. Specific examples of epichlorohydrin resins include Sumire Resin 650 (30) (manufactured by Sumitomo Chemical), Sumire Resin 675A (manufactured by Sumitomo Chemical), Sumire Resin 6615 (manufactured by Sumitomo Chemical), WS4002 ( Starlight PMC), WS4020 (Starlight PMC), WS4024 (Starlight PMC), WS4030 (Starlight PMC), WS4046 (Starlight PMC), WS4010 (Starlight PMC), CP8970 (Starlight PMC) Etc.).

The polyamine / amide resin used in the constitution of the protective layer 1 is a resin characterized by having no epoxy group in the molecule. Examples include polyamide urea resins, polyalkylene polyamine resins, polyalkylene polyamide resins, polyamine polyurea resins, modified polyamine resins, modified polyamide resins, polyalkylene polyamine urea formalin resins, polyalkylene polyamine polyamide polyurea resins, and the like. These can be used alone or in combination. Specific examples of the polyamine / amide resin include Sumire Resin 302 (manufactured by Sumitomo Chemical: polyamine polyurea resin), Sumire Resin 712 (manufactured by Sumitomo Chemical: polyamine polyurea resin), Sumire Resin 703 (Sumitomo Chemical). Company: Polyamine polyurea resin), Sumire Resin 636 (Sumitomo Chemical: polyamine polyurea resin), Sumire Resin SPI-100 (Sumitomo Chemical: modified polyamine resin), Sumire Resin SPI-102A (Sumitomo Chemical Co., Ltd .: modified polyamine resin), Sumire Resin SPI-106N (Sumitomo Chemical Co., Ltd .: modified polyamide resin), Sumire Resin SPI-203 (50) (Sumitomo Chemical Co., Ltd.), Sumire Resin SPI-198 (Manufactured by Sumitomo Chemical), printable A-700 (manufactured by Asahi Kasei), printable A 600 (manufactured by Asahi Kasei Co., Ltd.), PA6500, PA6504, PA6664, PA6638, PA6640, PA6664, PA6664, PA6654, PA6702, PA6704 (manufactured by Starlight PMC: polyalkylene polyamine polyamide polyurea resin), CP8994 (manufactured by Starlight PMC: Polyethyleneimine resin). Although there is no particular limitation, polyamine resin (polyalkylene polyamine resin, polyamine polyurea resin, modified polyamine resin, polyalkylene polyamine urea formalin resin, polyalkylene polyamine polyamide polyurea resin) is used because the printing density is good. It is preferable to do.

The content of epichlorohydrin resin and polyamine / amide resin used in the constitution of the protective layer 1 is preferably 1 to 100 parts by weight with respect to 100 parts by weight of carboxy-modified polyvinyl alcohol, and 5 to 50, respectively. More preferred are parts by weight. When the content is 1 part by weight or more, more preferably 5 parts by weight or more, respectively, good water resistance and water blocking resistance can be obtained. Further, when the content is 100 parts by weight or less, more preferably 50 parts by weight or less, respectively, increase in viscosity of the coating liquid and gelation hardly occur, and the operability is good.

[Protective layer 2]
A non-core shell type acrylic resin having a glass transition point (Tg) higher than 50 ° C. is contained in the protective layer. When the protective layer of the present invention is a constitution of the protective layer 2, that is, a constitution in which a non-core shell type acrylic resin having a glass transition point (Tg) higher than 50 ° C. is contained, excellent water resistance and water blocking resistance are specifically exhibited. To express. The acrylic resin used in the present invention contains (meth) acrylic acid and a monomer component copolymerizable with (meth) acrylic acid. (Meth) acrylic acid is preferably blended in an amount of 1 to 10 parts per 100 parts of the acrylic resin. (Meth) acrylic acid is alkali-soluble and has the property of making an acrylic resin a water-soluble resin by the addition of a neutralizing agent. By changing the acrylic resin to a water-soluble resin, particularly when a pigment is contained in the protective layer, the binding property to the pigment is remarkably improved, and a protective layer having excellent strength even when containing a large amount of pigment is formed. be able to. Examples of components copolymerizable with (meth) acrylic acid include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, By alkyl acrylate resins such as pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, and epoxy resins, silicone resins, styrene or derivatives thereof Modified alkyl acrylate resins such as the above-mentioned alkyl acrylate resins, (meth) acrylonitrile, acrylate esters, and hydroxyalkyl acrylate esters can be exemplified, but in particular, (meth) acrylonitrile and / or methyl methacrylate is blended. Is preferred. (Meth) acrylonitrile is preferably blended in an amount of 15 to 70 parts per 100 parts of the acrylic resin. Moreover, it is preferable that methyl methacrylate contains 20-80 parts in 100 parts of acrylic resins. When (meth) acrylonitrile and methyl methacrylate are included, it is preferable to blend 15 to 18 parts of (meth) acrylonitrile in 100 parts of acrylic resin and 20 to 80 parts of methyl methacrylate in 100 parts of acrylic resin.
The glass transition point (Tg) of the acrylic resin used in the present invention is higher than 50 ° C. When Tg is 50 ° C. or lower, the water resistance is improved, but sufficient heat resistance cannot be obtained, so that sticking tends to occur. On the other hand, when Tg is high, the stick resistance and scratch resistance tend to improve, but the protective layer becomes brittle, and the desired effects such as insufficient water resistance, plasticizer resistance and solvent resistance are obtained. Therefore, Tg is preferably 95 ° C. or lower. Tg of acrylic resin is measured by differential scanning calorimetry (DSC).

The acrylic resin used in the present invention is a non-core shell type acrylic resin. In general, the core-shell type acrylic resin is frequently used because it has better heat resistance than the non-core-shell type acrylic resin, and has excellent stick resistance when used in a coating layer. However, since the shell portion of the core-shell type acrylic resin usually has a low thermal conductivity, it also has the disadvantage of poor color development sensitivity. On the other hand, the ordinary non-core shell type acrylic resin has low heat resistance and has the disadvantage that sticks and head debris are easily generated. However, the non-core shell type acrylic resin used in the present invention has a glass transition point (Tg). Is higher than 50 ° C. and excellent in heat resistance, and therefore, there is an advantage that the color development sensitivity is good, and the stick resistance and head residue resistance are good.

When the protective layer of the present invention has the structure of the protective layer 1 or the structure of the protective layer 2, the protective layer may be completely saponified polyvinyl alcohol or partially saponified polyvinyl alcohol as long as the desired effect is not hindered. Acetoacetylated polyvinyl alcohol, carboxy modified polyvinyl alcohol, amide modified polyvinyl alcohol, sulfonic acid modified polyvinyl alcohol, butyral modified polyvinyl alcohol, olefin modified polyvinyl alcohol, nitrile modified polyvinyl alcohol, pyrrolidone modified polyvinyl alcohol, silicone modified polyvinyl alcohol, other Modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, acetyl cellulose, styrene-anhydrous Inic acid copolymer, styrene-butadiene copolymer, casein, arabic rubber, oxidized starch, etherified starch, dialdehyde starch, esterified starch, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylic acid ester, polyvinyl butyral Further, it is possible to contain a binder such as polystyrose and copolymers thereof, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, and coumaro resin. These polymer substances are used by dissolving them in solvents such as water, alcohol, ketones, esters, hydrocarbons, etc., and are used in the state of being emulsified or pasted in water or other media to achieve the required quality. It can also be used in combination.

Next, other various materials used in the present invention are exemplified, but these are necessary in addition to the heat-sensitive recording layer, the protective layer, and the heat-sensitive recording layer and the protective layer as long as the desired effects on the above problems are not impaired. It can be used for each coating layer provided according to.

As the electron-accepting developer used in the heat-sensitive recording material of the present invention (hereinafter, also referred to as “developer”), all known ones in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used, Although not particularly limited, for example, 4,4′-isopropylidenediphenol, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane 4,4′-dihydroxydiphenyl sulfide, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate, 4,4′-dihydroxydiphenylsulfone, 2,4′-dihydroxydiphenylsulfone, 4-hydroxy-4′-isopropoxydiphenyl Sulfone, 4-hydroxy-4′-n-propoxydiphenyl sulfone, bis (3-allyl-4- Droxyphenyl) sulfone, 4-hydroxy-4′-allyloxydiphenylsulfone, 4-hydroxy-4′-methyldiphenylsulfone, 4-hydroxyphenyl-4′-benzyloxyphenylsulfone, 3,4-dihydroxyphenyl-4 '-Methylphenylsulfone, aminobenzenesulfonamide derivatives described in JP-A-8-59603, bis (4-hydroxyphenylthioethoxy) methane, 1,5-di (4-hydroxyphenylthio) -3-oxapentane, Butyl bis (p-hydroxyphenyl) acetate, methyl bis (p-hydroxyphenyl) acetate, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,4-bis [α-methyl-α- ( 4′-hydroxyphenyl) ethyl] benzene, 1,3-bis [α-methyl Ru-α- (4′-hydroxyphenyl) ethyl] benzene, di (4-hydroxy-3-methylphenyl) sulfide, 2,2′-thiobis (3-tert-octylphenol), 2,2′-thiobis (4 -Tert-octylphenol), phenolic compounds such as diphenylsulfone cross-linked compounds described in International Publication No. WO 97/16420, developer compositions described in International Publication No. WO 02/098674, International Publication No. WO 02/081229 or JP Compounds described in 2002-301873, 4,4′-bis-3- (phenoxycarbonylamino) methylphenylureido) diphenylsulfone (trade name: UU manufactured by Asahi Kasei Co., Ltd.), N, N′-di-m-chlorophenylthiourea, etc. Thiourea compounds, p-chlorobenzoic acid, stearyl gallate, bis [ 4- (n-octyloxycarbonylamino) salicylic acid zinc] dihydrate, 4- [2- (p-methoxyphenoxy) ethyloxy] salicylic acid, 4- [3- (p-tolylsulfonyl) propyloxy] salicylic acid, 5 -[P- (2-p-methoxyphenoxyethoxy) cumyl] aromatic carboxylic acids of salicylic acid and polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel of these aromatic carboxylic acids Examples thereof include salts with salts, antipyrine complexes of zinc thiocyanate, and complex zinc salts of terephthalaldehyde acid with other aromatic carboxylic acids. A phenolic compound such as the diphenylsulfone cross-linking compound described in International Publication No. WO 97/16420 is available as a trade name D-90 manufactured by Nippon Soda Co., Ltd. The compounds described in International Publication No. WO02 / 081229 or JP-A-2002-301873 are available as trade names D-102 and D-100 manufactured by Nippon Soda Co., Ltd. These developers can be used alone or in combination of two or more. Among these, 4-hydroxy-4′-isopropoxydiphenyl sulfone is particularly preferable because of excellent color development sensitivity. In addition, a metal chelate color-developing component such as a higher fatty acid metal double salt and a polyvalent hydroxyaromatic compound described in JP-A-10-258577 can also be contained.

As the electron-donating leuco dye (hereinafter, also referred to as “leuco dye”) used in the present invention, any known one in the field of conventional pressure-sensitive or thermal recording paper can be used, and is not particularly limited. However, triphenylmethane compounds, fluorane compounds, fluorene compounds, divinyl compounds and the like are preferable. Specific examples of typical colorless or light-colored dyes (dye precursors) are shown below. These dye precursors may be used alone or in combination of two or more.
<Triphenylmethane leuco dye>
3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone); 3,3-bis (p-dimethylaminophenyl) phthalide (also known as malachite green lactone)

<Fluoran leuco dye>
3-diethylamino-6-methylfluorane; 3-diethylamino-6-methyl-7-anilinofluorane; 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluorane; 3-diethylamino- 6-methyl-7-chlorofluorane; 3-diethylamino-6-methyl-7- (m-trifluoromethylanilino) fluorane; 3-diethylamino-6-methyl-7- (o-chloroanilino) fluorane; Diethylamino-6-methyl-7- (p-chloroanilino) fluorane; 3-diethylamino-6-methyl-7- (o-fluoroanilino) fluorane; 3-diethylamino-6-methyl-7- (m-methylanilino) fluorane 3-diethylamino-6-methyl-7-n-octylanilinofluorane; 3-diethylamino-6-methyl-7-n-octylaminofluorane; 3-diethylamino-6-methyl-7-benzylaminofluorane; 3-diethylamino-6-methyl-7-dibenzylaminofluorane; 3-diethylamino-6-chloro-7-anilinofluorane; 3-diethylamino-6-chloro-7-p-methylanilinofluorane; 3-diethylamino-6 3-Ethoxyethyl-7-anilinofluorane; 3-diethylamino-7-methylfluorane; 3-diethylamino-7-chlorofluorane; 3-diethylamino-7- (m-trifluoromethylanilino) fluorane; Diethylamino-7- (o-chloroanilino) fluorane; 3-diethyla 3-diethylamino-7- (o-fluoroanilino) fluorane; 3-diethylamino-benzo [a] fluorane; 3-diethylamino-benzo [c] fluorane; 3-dibutylamino -6-methyl-fluorane; 3-dibutylamino-6-methyl-7-anilinofluorane; 3-dibutylamino-6-methyl-7- (o, p-dimethylanilino) fluorane; 3-dibutylamino- 6-methyl-7- (o-chloroanilino) fluorane; 3-dibutylamino-6-methyl-7- (p-chloroanilino) fluorane; 3-dibutylamino-6-methyl-7- (o-fluoroanilino) fluorane 3-dibutylamino-6-methyl-7- (m-trifluoromethylanilino) fluorane 3-dibutylamino-6-methyl-chlorofluorane; 3-dibutylamino-6-ethoxyethyl-7-anilinofluorane; 3-dibutylamino-6-chloro-7-anilinofluorane; 3-dibutylamino -6-methyl-7-p-methylanilinofluorane; 3-dibutylamino-7- (o-chloroanilino) fluorane; 3-dibutylamino-7- (o-fluoroanilino) fluorane; 3-di-n -Pentylamino-6-methyl-7-anilinofluorane; 3-di-n-pentylamino-6-methyl-7- (p-chloroanilino) luolane; 3-di-n-pentylamino-7- (m -Trifluoromethylanilino) fluoran; 3-di-n-pentylamino-6-chloro-7-anilinofluoran; 3-di-n-pentyla 3-pyrrolidino-6-methyl-7-anilinofluorane; 3-piperidino-6-methyl-7-anilinofluorane; 3- (N-methyl-N- Propylamino) -6-methyl-7-anilinofluorane; 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane; 3- (N-ethyl-N-cyclohexylamino) ) -6-Methyl-7-anilinofluorane; 3- (N-ethyl-N-xylamino) -6-methyl-7- (p-chloroanilino) fluorane; 3- (N-ethyl-p-toludino)- 6-methyl-7-anilinofluorane; 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane; 3- (N-ethyl-N-isoamyl) Mino) -6-chloro-7-anilinofluorane; 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane; 3- (N-ethyl-N-isobutyl) Amino) -6-methyl-7-anilinofluorane; 3- (N-ethyl-N-ethoxypropylamino) -6-methyl-7-anilinofluorane; 3-cyclohexylamino-6-chlorofluorane; 2- (4-oxahexyl) -3-dimethylamino-6-methyl-7-anilinofluorane; 2- (4-oxahexyl) -3-diethylamino-6-methyl-7-anilinofluorane; 2 -(4-oxahexyl) -3-dipropylamino-6-methyl-7-anilinofluorane; 2-methyl-6-p- (p-dimethylaminophenyl) aminoanily 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluorane; 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane; Chloro-6-p- (p-dimethylaminophenyl) aminoanilinofluorane; 2-nitro-6-p- (p-diethylaminophenyl) aminoanilinofluorane; 2-amino-6-p- (p- 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluorane; 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) aminoani Linofluorane; 2-benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane; 3-hydroxy-6-p- (p-phenylaminophenyl) aminoanilinofluorane; 3-methyl-6-p- (p-dimethylaminophenyl) aminoanilinofluorane; 3-diethylamino-6-p- ( p-diethylaminophenyl) aminoanilinofluorane; 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluorane; 2,4-dimethyl-6-[(4-dimethylamino) anilino]- Fluoran

<Fluorene leuco dye>
3,6,6′-tris (dimethylamino) spiro [fluorene-9,3′-phthalide]; 3,6,6′-tris (diethylamino) spiro [fluorene-9,3′-phthalide]

<Divinyl leuco dye>
3,3-bis- [2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrabromophthalide; 3,3-bis- [2- (P-dimethylaminophenyl) -2- (p-methoxyphenyl) ethenyl] -4,5,6,7-tetrachlorophthalide; 3,3-bis- [1,1-bis (4-pyrrolidinophenyl) ) Ethylene-2-yl] -4,5,6,7-tetrabromophthalide; 3,3-bis- [1- (4-methoxyphenyl) -1- (4-pyrrolidinophenyl) ethylene-2- Yl] -4,5,6,7-tetrachlorophthalide

<Others>
3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide; 3- (4-diethylamino-2-ethoxyphenyl) -3- ( 1-octyl-2-methylindol-3-yl) -4-azaphthalide; 3- (4-cyclohexylethylamino-2-methoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl)- 4-Azaphthalide; 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide; 3,6-bis (diethylamino) fluorane-γ- (3′-nitro) anilinolactam; -Bis (diethylamino) fluorane-γ- (4'-nitro) anilinolactam; 1,1-bis- [2 ', 2', 2 ", 2" -tetrakis- (p-dimethyla Nophenyl) -ethenyl] -2,2-dinitrileethane; 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2- β-naphthoylethane; 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,2-diacetylethane; bis- [2, 2,2 ′, 2′-tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester and the like.

In the present invention, conventionally known sensitizers can be used. Such sensitizers include ethylene bisamide, montanic acid wax, polyethylene wax, 1,2-di- (3-methylphenoxy) ethane, p-benzylbiphenyl, β-benzyloxynaphthalene, 4-biphenyl-p-tolyl ether. , M-terphenyl, 1,2-diphenoxyethane, 4,4′-ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxymethane, 1,2-di (3-methylphenoxy) ethylene, 1 , 2-diphenoxyethylene, bis [2- (4-methoxy-phenoxy) ethyl] ether, methyl p-nitrobenzoate, dibenzyl oxalate, di (p-chlorobenzyl) oxalate, di (p-methyl oxalate) Benzyl), dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p-tri Examples include carbonate, phenyl-α-naphthyl carbonate, 1,4-diethoxynaphthalene, 1-hydroxy-2-naphthoic acid phenyl ester, 4- (m-methylphenoxymethyl) biphenyl, orthotoluenesulfonamide, and paratoluenesulfonamide. However, the present invention is not limited to these. These sensitizers may be used alone or in combination of two or more.

As the binder used in the present invention, generally known binders are used, and specifically, fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, Polyvinyl alcohol binders such as butyral modified polyvinyl alcohol, other modified polyvinyl alcohols, cellulose binders such as hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, ethyl cellulose, acetyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer Polymer, polyvinyl chloride, polyvinyl acetate, polyacrylamide, polyacrylic acid ester, polyvinyl butyllar, polystyrene And their copolymers, polyamide resins, silicone resins, petroleum resins, terpene resins, ketone resins, coumarone resins, and polyvinyl alcohol grafted onto hydrophobic resins such as styrene-butadiene resins and acrylic resins. Polymerized binders and hydrophobic resin emulsion binders such as styrene-butadiene resins and acrylic resins using polyvinyl alcohol as an emulsifier can be mentioned. Among these, as the binder having a hydroxyl group, a polyvinyl alcohol-based binder or a cellulose-based binder is preferable, and a saponification degree of 90 mol% or less and / or unmodified polyvinyl alcohol is more preferable in terms of color development sensitivity, water resistance, and surface strength. . These binders are used by being dissolved in a solvent such as water, alcohol, ketone, ester, hydrocarbon, etc., and are used in a state of being emulsified or dispersed in water or other media, depending on the required quality. It can also be used in combination.
As a compounding quantity of a binder, 2.0-15.0 weight part is preferable with respect to the heat-sensitive recording layer total solid, and 4.0-10.0 weight part is more preferable. That is, when the blending amount of the binder is 4.0 parts by weight or less, the surface strength is low, and when it is 15.0 parts by weight or more, high color development sensitivity and water resistance are difficult to obtain.

As the pigment used in the present invention, generally known pigments are used, and inorganic pigments such as silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, aluminum hydroxide, colloidal silica, and organic pigments are used. These may be used alone or in combination of two or more. In addition, lubricants such as waxes and metal soaps, benzophenone and triazole UV absorbers, water-resistant agents such as glyoxal, dispersants, antifoaming agents, antioxidants, fluorescent dyes, etc. can be used. .

In the present invention, 4,4′-butylidene (6-tert-butyl-3-methylphenol), 2, and the like are used as stabilizers for imparting oil resistance and the like of recorded images within a range that does not impair the desired effect. 2′-di-t-butyl-5,5′-dimethyl-4,4′-sulfonyldiphenol, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1, Add 1,3-tris (2-methyl-4-hydroxy-5-t-butylphenylbutane, 4-benzyloxy-4 '-(2,3-epoxy-2-methylpropoxy) diphenylsulfone, epoxy resin, etc. You can also
The types and amounts of the leuco dye, developer, and other various components used in the heat-sensitive recording material of the present invention are determined according to the required performance and recording suitability, and are not particularly limited. About 0.5 to 10 parts of developer, 0.5 to 10 parts of sensitizer, and 0.5 to 10 parts of pigment are used.

The leuco dye, color developer, and materials to be added as necessary are finely pulverized to a particle size of several microns or less with a pulverizer such as a ball mill, attritor or sand glider or an appropriate emulsifier, and depending on the binder and purpose. Add various additive materials to make a coating solution.

By applying the coating liquid having the above composition to any support such as paper, recycled paper, synthetic paper, film, plastic film, foamed plastic film, non-woven fabric, etc., the desired thermal recording material can be obtained. Moreover, you may use the composite sheet which combined these as a support body.

The means for applying the coating liquid to the support is not particularly limited, and can be applied in accordance with a well-known conventional technique. For example, the off coater equipped with various coaters such as an air knife coater, a rod blade coater, a bill blade coater, and a roll coater. A machine coater or an on-machine coater is appropriately selected and used. The coating amount of the heat-sensitive recording layer is not particularly limited and is usually in the range of ² to 12 g / m ^{2 by} dry weight. The coating amount of the protective layer provided on the heat-sensitive recording layer is not particularly limited, but a solid content in the range of 0.5 to 3 g / m ² is preferable because particularly good print density and image quality can be obtained.

In the heat-sensitive recording material of the present invention, an undercoat layer such as a polymer material containing a filler can be provided under the heat-sensitive recording layer for the purpose of further enhancing the color development sensitivity. It is also possible to correct the curl by providing a backcoat layer on the opposite side of the support from the thermosensitive recording layer. Also, various known techniques in the heat-sensitive recording material field can be added as appropriate, such as applying a smoothing process such as supercalendering after coating each layer.

The following examples illustrate the invention but are not intended to limit the invention. In each example, “part” means “part by weight” unless otherwise specified.
[Example 1]
A composition comprising the following composition was stirred and dispersed to prepare an undercoat layer coating solution.
<Undercoat layer coating solution>
Baked kaolin (manufactured by Engelhard, Ansilex 90) 100 parts Styrene-butadiene copolymer latex (solid content 48%) 40 parts Completely saponified polyvinyl alcohol (manufactured by Kuraray, PVA117) 10% aqueous solution 30 parts Water 160 parts The undercoat layer coating solution was applied to one side of a support (high-quality paper having a basis weight of 50 g / m ² ) so that the coating amount was 8.0 g / m ^2, and then dried to obtain an undercoat layer coated paper. .

Each of the dye, developer, and sensitizer materials was prepared in advance as a dispersion having the following composition, and wet grinding was performed with a sand grinder until the average particle size became 0.5 μm.
<Developer dispersion>
4-hydroxy-4'-isopropoxydiphenyl sulfone (manufactured by API Corporation) 6.0 parts polyvinyl alcohol 10% aqueous solution (manufactured by Nippon Synthetic Chemical Co., Ltd., GL-03, polymerization degree: 300, saponification degree: 88 mol%) 18.8 parts Water 11.2 parts
<Dye dispersion>
3-di-n-butylamino-6-methyl-7-anilinofluorane (manufactured by Yamada Chemical Co., ODB-2) 3.0 parts Polyvinyl alcohol 10% aqueous solution (GL-03) 6.9 parts water 9 copies
<Sensitizer dispersion>
1,2-di- (3-methylphenoxy) ethane (manufactured by Sanko Co., Ltd., KS232) 6.0 parts Polyvinyl alcohol 10% aqueous solution (GL-03) 18.8 parts Water 11.2 parts

The above dispersions were mixed at the ratio shown below to obtain a thermal recording layer coating solution.
<Thermosensitive recording layer coating solution>
Developer dispersion 36.0 parts Dye dispersion 13.8 parts Sensitizer dispersion 36.0 parts Silica (Degussa Japan, Carplex 101) 50% dispersion 13.0 parts Calcium carbonate (Shiraishi Calcium Co., Ltd.) Manufactured, Tunex E) 50% dispersion 13.0 parts fully saponified polyvinyl alcohol (manufactured by Kuraray Co., Ltd., PVA117) 10% aqueous solution 20.0 parts Phosphate ester compound (manufactured by Chukyo Yushi Co., Separ M835, solid content 20%) 4 Next, 0.0 parts of the heat-sensitive recording layer coating liquid was applied onto the undercoat layer of the undercoat layer-coated paper so that the coating amount was 3.0 g / m ² , followed by drying to obtain a heat-sensitive recording material.

[Example 2]
A heat-sensitive recording material was produced in the same manner as in Example 1 except that no phosphoric acid ester compound was added to the heat-sensitive recording layer. Subsequently, the mixture which consists of the following ratio was mixed and it was set as the protective layer coating liquid.
<Protective layer coating solution>
Aluminum hydroxide (manufactured by Martinsberg, Martinfin) 50% dispersion 12.0 parts Completely saponified polyvinyl alcohol (manufactured by Kuraray Co., PVA117) 10% aqueous solution 25.0 parts Glyoxal (manufactured by Nippon Gosei Co., Ltd.) 40% aqueous solution 5 0.0 part phosphoric acid ester compound (manufactured by Chukyo Yushi Co., Separ M835, solid content 20%) 7.6 parts The coating amount of the above protective layer coating solution on the heat-sensitive recording layer of the heat-sensitive recording material is 2.0 g / m. After coating so as to be ² , drying was performed to obtain a heat-sensitive recording material.
[Example 3]
A heat-sensitive recording material was obtained in the same manner as in Example 2 except that the formulation of the protective layer coating solution was changed to the following protective layer coating solution 2.
<Protective layer coating solution 2>
Aluminum hydroxide (Martinsberg, Martinfin) 50% dispersion 12.0 parts Carboxy-modified polyvinyl alcohol (Kuraray, KL118) 12% aqueous solution 26.7 parts Polyamide epichlorohydrin resin (Seiko PMC) , WS4030, solid content 25%) 3.8 parts modified polyamide resin (manufactured by Sumitomo Chemical Co., Ltd., Sumirez Resin SPI102, solid content 45%) 2.1 parts phosphoric acid ester compound (manufactured by Chukyo Yushi Co., Separ M835, solid content) 20%) 7.6 parts [Example 4]
A heat-sensitive recording material was obtained in the same manner as in Example 2 except that the formulation of the protective layer coating solution was changed to the following protective layer coating solution 3.
<Protective layer coating solution 3>
Aluminum hydroxide (Martinsberg, Martin Fin) 50% dispersion 12.0 parts Non-core shell acrylic resin (Mitsui Chemicals, ASN1004K, Tg 55 ° C., solid content 18%) 30.0 parts phosphate ester Compound (Chukyo Yushi Co., Separ M835, solid content 20%) 7.6 parts

[Comparative Example 1]
In Example 1, a heat-sensitive recording material was obtained in the same manner as in Example 1 except that no phosphate ester compound was blended in the heat-sensitive recording layer.
[Comparative Example 2]
In Example 2, a heat-sensitive recording material was obtained in the same manner as in Example 2 except that no phosphate ester compound was blended in the protective layer.
[Comparative Example 3]
In Example 1, a heat-sensitive recording material was obtained in the same manner as in Example 1 except that 2.1 parts of calcium stearate was blended in the heat-sensitive recording layer without blending the phosphate ester compound.
[Comparative Example 4]
In Example 2, a heat-sensitive recording material was obtained in the same manner as in Example 2 except that 1.5 parts of calcium stearate was blended in the protective layer without blending the phosphate ester compound.

The following evaluation was performed on the heat-sensitive recording materials obtained in the above Examples and Comparative Examples.
[Color development sensitivity]
Using TH-PMD manufactured by Okura Electric Co., Ltd., printing was performed on the created thermal recording medium with an applied energy of 0.34 mJ / dot. The image density after printing and after the quality test was measured with a Macbeth densitometer (RD-914, using an amber filter).
[Stick resistance]
When using a TH-PMD manufactured by Okura Electric Co., Ltd. and printing on a thermal recording medium in an environment with an applied energy of 0.34 mJ / dot, a printing speed of 50 mm / sec, and a temperature of −10 ° C. The noise was evaluated according to the following criteria.
○: No whiteout and almost no noise △: Some whiteout but almost no noise ×: Whiteout occurs frequently and noise is high [Adhesion to head residue]
30 cm long grid printing was performed with a label printer (printer name: Respre R-8) manufactured by SATO, and the head residue and print samples adhering to the thermal head after printing were visually observed.
○: No head debris is attached to the thermal head. Δ: Head debris is adhered to the thermal head, but the printed part is not faint. X: Head debris is adhered to the thermal head, and the printed part is faint.

The evaluation results are shown in Table 1.

Claims (4)

A heat-sensitive recording material provided with a heat-sensitive recording layer containing a colorless or light-colored electron-donating leuco dye and an electron-accepting developer on a support, wherein the outermost layer contains a phosphate compound. Thermal recording material. The heat-sensitive recording material according to claim 1, wherein the outermost layer is a protective layer. The heat-sensitive recording material according to claim 2, wherein the protective layer contains an epichlorohydrin resin and a polyamine / amide resin together with carboxy-modified polyvinyl alcohol. The heat-sensitive recording material according to claim 2, wherein the protective layer contains a non-core shell acrylic resin having a glass transition point (Tg) higher than 50C.