Printing ink for heat-sensitive recording medium

Abstract

The present disclosure is a printing ink for a heat-sensitive recording medium, which is the following (A) or (B): (A) a heat-sensitive color-developing printing ink that contains a leuco dye, a color developing agent, a vinyl pyrrolidone-vinyl acetate copolymer, and a solvent, in which the color developing agent is at least one selected from the group consisting of: an N, N '-diarylurea compound represented by general formula (1) (in the formula, R1 represents a hydrogen atom or a methyl group); and R0 represents a C1-12 alkyl group, a C7-12 aralkyl group, or a C6-12 aryl group. The aralkyl group and the aryl group may be substituted by a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom. The plurality of R0 may be the same or different. A1 represents a hydrogen atom or a C1-4 alkyl group. The plurality of A1 may be the same or different. ), a compound represented by general formula (2) (in the formula, R1 to R5 may be the same or different and each represents a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group. The catalyst is 5-(N-3-methylphenyl-sulfamoyl)-N ', N' '-bis-(3-methylphenyl)-isophthalic acid diamide; and (B) a protective layer printing ink for a heat-sensitive recording medium, the protective layer printing ink containing an adhesive, a sliding property imparting agent, and a solvent, the adhesive being a polyvinyl acetal resin, and the sliding property imparting agent being an alkyl phosphate ester and / or a salt thereof.

Description

TECHNICAL FIELD

[0001] The present application relates to a printing ink for a heat-sensitive recording body, a heat-sensitive recording body, and an image recording method. BACKGROUND

[0002] Heat-sensitive recording bodies using a color development reaction between a leuco dye and a color developer are relatively inexpensive, and their recording devices are compact and easy to maintain. Therefore, these heat-sensitive recording bodies are widely used not only as recording media for faxes, various calculators, and CAD plotters, but also as label solutions for food products (including fresh foods, boxed lunches, and prepared dishes), medical items (including labels for drug management), and process control.

[0003] For labels, top seal materials, or tapes on transparent containers of food products such as salads or prepared meals, a high transparency medium is often essential to clearly show the contents. In these applications, a transparent heat film is often used, including a transparent PET film as a base material.

[0004] Patent Document 1 reports a heat-sensitive recording medium that has all of the following properties: hot water resistance, water resistance, ethanol resistance, warm humidity resistance, wet abrasion resistance, and heat resistance, while also producing a high concentration image. The heat-sensitive recording medium includes a support body and a heat-sensitive recording layer on the support body, in which the heat-sensitive recording layer contains a specific N,N'-diaryl urea-based compound and a styrene-acrylic-based resin. In addition, the examples of Patent Document 1 disclose using a PET film as the support body, forming a protective layer containing a styrene-acrylic-based resin, an oxidized polyethylene wax, and calcium carbonate.

[0005] Patent Document 2 reports a heat-sensitive recording layer forming liquid that is capable of forming a heat-sensitive recording layer having excellent surface uniformity without tailing and coating unevenness, and having minimal thickness variation, and discloses that the heat-sensitive recording layer forming liquid contains an electron-donating compound, an electron-accepting compound having a solubility of 5 mass% or less in 100% ethanol at 20°C, and a solvent.

[0006] Patent Document 3 reports obtaining a heat-developing film by applying a heat-developing ink to a support base material to form a heat-developing ink layer, then forming a protective layer composed of a resin coating layer containing magnesium oxide on the upper surface of the heat-developing ink layer, and the heat-developing film has both heat resistance and water resistance.

[0007] PRIOR ART DOCUMENTS

[0008] PATENT DOCUMENT

[0009] Patent Document 1: JP 2022-146283 A

[0010] Patent Document 2: JP 2022-151636 A

[0011] Patent Literature 3: Japanese Patent No. 3382728 SUMMARY

[0012] PROBLEMS TO BE SOLVED BY THE INVENTION

[0013] An object of the present application is to provide a heat-sensitive color developing printing ink; a heat-sensitive recording body using the heat-sensitive color developing printing ink, which is high in sensitivity and exhibits excellent resistance to background fogging and plasticizer resistance; and an image recording method using the heat-sensitive color developing printing ink.

[0014] In another embodiment, an object of the present application is to provide a protective layer printing ink for a heat-sensitive recording body, and a heat-sensitive recording body using the protective layer printing ink, which exhibits excellent print preservation and thermal head matching.

[0015] SOLUTION TO PROBLEM

[0016] In view of the prior art, the present inventors have conducted extensive studies and have successfully achieved the objects. Specifically, the present application relates to the following heat-sensitive recording body printing ink, heat-sensitive recording body, and image recording method.

[0017] Item 1.

[0018] A printing ink for a heat-sensitive recording body, which is the following (A) or (B):

[0019] (A) a heat-sensitive color developing printing ink comprising a leuco dye, a color developer, a vinylpyrrolidone-vinyl acetate copolymer, and a solvent,

[0020] wherein the heat-sensitive color developing printing ink comprises at least one selected from the group consisting of the following compounds as the color developer:

[0021] an N,N'-diaryl urea-based compound represented by the following formula (1):

[0022]

[0023] wherein

[0024] R 0 represents a C 1-12 alkyl group, a C 7-12 aralkyl group, or a C 6-12 aryl group, wherein the aralkyl group and the aryl group can be substituted with a C 1-12 alkyl group, a C 1-12 alkoxy group, a C 6-12 aryl group, or a halogen atom, and a plurality of R 0 may be the same or different, and

[0025] A 1 represents a hydrogen atom or a C 1-4 alkyl group, and a plurality of A1 may be the same or different;

[0026] a compound represented by the following formula (2):

[0027]

[0028] wherein

[0029] R 1 to R 5 are the same or different, and represent a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group; and

[0030] 5-(N-3-methylphenyl-sulfamoyl)-N',N''-bis-(3-methylphenyl)-isophthalic acid diamide, and

[0031] (B) a protective layer printing ink for a heat-sensitive recording material, comprising a binder, a sliding property-imparting agent, and a solvent, wherein the protective layer printing ink comprises a polyvinyl acetal resin as the binder and an alkyl phosphate ester and / or a salt thereof as the sliding property-imparting agent.

[0032] Item 2.

[0033] The printing ink according to Item 1, wherein the printing ink is a heat-sensitive color-developing printing ink (A).

[0034] Item 3.

[0035] The printing ink according to Item 2, wherein the content of the leuco dye is 15 mass% to 40 mass%, the content of the color developer is 20 mass% to 70 mass%, and the content of the vinylpyrrolidone-vinyl acetate copolymer is 5 mass% to 35 mass%, based on the total solid content of the heat-sensitive color-developing printing ink.

[0036] Item 4.

[0037] The printing ink according to Item 2 or 3, wherein the molar ratio of vinylpyrrolidone to vinyl acetate in the vinylpyrrolidone-vinyl acetate copolymer is 50 / 50 to 30 / 70.

[0038] Item 5.

[0039] The printing ink according to any one of Items 2 to 4, further comprising colloidal silica having an average particle diameter of 45 nm or less, wherein the content of the colloidal silica is 5 mass% to 30 mass%, based on the total solid content of the heat-sensitive color-developing printing ink.

[0040] Item 6.

[0041] The printing ink according to any one of items 2 to 5, which comprises water and an alcohol as a solvent.

[0042] Item 7.

[0043] The printing ink according to item 1, wherein the printing ink is a (B) protective layer printing ink for a heat-sensitive recording body.

[0044] Item 8.

[0045] The printing ink according to item 7, wherein the content of the polyvinyl acetal resin is 75 mass% to 99 mass% and the content of the alkyl phosphate and / or salt thereof is 1 mass% to 25 mass%, based on the total solid content of the protective layer printing ink.

[0046] Item 9.

[0047] The printing ink according to item 7 or 8, wherein the number average molecular weight of the polyvinyl acetal resin is 17,000 to 40,000.

[0048] Item 10.

[0049] The printing ink according to any one of items 7 to 9, wherein the alkyl phosphate salt is in a Na-neutralized or Ca-neutralized form thereof, and the first acid value of the alkyl phosphate is 135 mgKOH / g or less.

[0050] Item 11.

[0051] The printing ink according to any one of items 7 to 10, which further comprises a calcined kaolin having an average particle diameter of 2.0 μm or less, wherein the content of the calcined kaolin is 0.5 mass% to 10 mass%, based on the total solid content of the protective layer printing ink.

[0052] Item 12.

[0053] The printing ink according to any one of items 7 to 11, which comprises an alcohol and a naphthene as a solvent.

[0054] Item 13.

[0055] The printing ink according to any one of items 1 to 12, wherein the printing ink is an ink for gravure printing.

[0056] Item 14.

[0057] A heat-sensitive recording body, which comprises

[0058] a support body, and

[0059] a heat-sensitive recording layer formed of the printing ink according to any one of items 1 to 6 and item 13 on one surface or at least a part of both surfaces of the support body and / or a protective layer formed of the printing ink according to item 1 and any one of items 7 to 13.

[0060] Item 15.

[0061] The heat-sensitive recording body according to item 14, wherein the support is a semi-transparent or transparent support made of glassine paper or laminated resin paper, or a transparent film made of cellophane or a synthetic resin film.

[0062] Item 16.

[0063] The heat-sensitive recording body according to item 14 or 15, which includes a print layer on at least a portion of a surface of the support opposite to a surface on which the heat-sensitive recording layer is present.

[0064] Item 17.

[0065] The heat-sensitive recording body according to any one of items 14 to 16, which includes a heat-seal layer on at least a portion of one surface or both surfaces of the support.

[0066] Item 18.

[0067] The heat-sensitive recording body according to any one of items 14 to 17, which includes a primer layer between the support and the heat-sensitive recording layer.

[0068] Item 19.

[0069] The heat-sensitive recording body according to item 18, wherein the primer layer contains a chlorinated polyolefin resin as a binder.

[0070] Item 20.

[0071] The heat-sensitive recording body according to any one of items 17 to 19, which is used as a lid material for top sealing.

[0072] Item 21.

[0073] An image recording method, which includes recording an image on the heat-sensitive recording body according to any one of items 14 to 20 by using a laser or a thermal head.

[0074] Advantages of the Invention

[0075] A heat-sensitive recording body including a heat-sensitive recording layer formed using a heat-sensitive color developing print ink of the present invention exhibits high sensitivity and excellent resistance to background fogging and resistance to plasticizer. The heat-sensitive recording body also exhibits excellent transparency.

[0076] A heat-sensitive recording body including a protective layer formed using a protective layer print ink of the present invention exhibits excellent print preservation and thermal head matching. The heat-sensitive recording body also exhibits excellent transparency. DETAILED DESCRIPTION

[0077] In the present specification, the expression "comprise" or "contain" includes the concepts of "comprising", "consisting essentially of", and "consisting of".

[0078] In the present specification, a numerical range indicated by "to" means a range including the lower limit and upper limit values given before and after "to" as the lower limit and upper limit.

[0079] As used herein, "latex" includes latex in the form of a gel or a dry film formed by drying a dispersion medium.

[0080] The printing ink for a heat-sensitive recording body of the present application is the following (A) or (B):

[0081] (A) a heat-sensitive color developing printing ink comprising a leuco dye, a color developer, a vinylpyrrolidone-vinyl acetate copolymer, and a solvent,

[0082] wherein the heat-sensitive color developing printing ink comprises at least one selected from the group consisting of the following as the color developer:

[0083] an N,N'-diaryl urea-based compound represented by the following formula (1):

[0084]

[0085] wherein

[0086] R 0 represents a hydrogen atom or a C 1-12 alkyl group, and a plurality of R 7-12 may be the same or different, and 6-12 aryl group, wherein the aralkyl group and the aryl group can be substituted with a C 1-12 alkyl group, a C 1-12 alkoxy group, a C 6-12 aryl group, or a halogen atom, and a plurality of R 0 may be the same or different, and

[0087] A 1 represents a hydrogen atom or a C 1-4 alkyl group, and a plurality of A 1 may be the same or different;

[0088] a compound represented by the following formula (2):

[0089]

[0090] wherein

[0091] R 1 to R 5the same or different, and represent a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group, or an arylamino group; and

[0092] 5-(N-3-methylphenyl-sulfamoyl)-N',N''-bis-(3-methylphenyl)-isophthalamide, and

[0093] (B) a protective layer printing ink for a heat-sensitive recording body, which comprises a binder, a sliding property-imparting agent, and a solvent, wherein the protective layer printing ink comprises a polyvinyl acetal resin as the binder and an alkyl phosphate ester and / or a salt thereof as the sliding property-imparting agent.

[0094] The heat-sensitive recording body of the present application also includes a heat-sensitive recording layer formed from the heat-sensitive color-developing printing ink of the present application and / or a protective layer formed from the protective layer printing ink of the present application on at least a part of one surface or both surfaces of the support.

[0095] Thermosensitive color developing printing ink

[0096] Leuco dye

[0097] The heat-sensitive color-developing printing ink of the present application can contain any of various known colorless or light-colored leuco dyes. Specific examples of such leuco dyes are described below.

[0098] Specific examples of leuco dyes include dyes capable of developing blue color, such as 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylamino-2- methylphenyl)-3-(4-dimethylaminophenyl)-6-dimethylaminophthalide, and fluoran; dyes capable of developing green color, such as 3-(N-ethyl-N-p-tolyl)amino-7-N- methylaminofluoran, 3-diethylamino-7-anilinofluoran, 3-diethylamino-7- dibenzylaminofluoran, and rhodamine B-anilinolactam; dyes capable of developing red color, such as 3,6-bis(diethylamino)fluoran-gamma-anilinolactam, 3-cyclohexylamino-6- chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, and 3-diethylamino-7- chlorofluoran;dyes capable of developing a black colour, such as 3-(N-ethyl-N-isopentyl)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-anilinofluorane, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-7-(m-trifluoromethylanilino)fluorane, 3-(N-isopentyl-N-ethylamino)-7-(o-chloroanilino)fluorane, 3-(N-ethyl-N-2-tetrahydrofurylamino)-6-methyl-7-anilinofluorane, 3-(N-n-hexyl-N-ethylamino)-6-methyl-7-anilinofluorane, 3-[N-(3-ethoxypropyl)-N-ethylamino]-6-methyl-7-anilinofluorane, 3-[N-(3-ethoxypropyl)-N-methylamino]-6-methyl-7-anilinofluorane, 3-diethylamino-7-(2-chloroanilino)fluorane, 3-di(n-butylamino)-7-(2-chloroanilino)fluorane, 4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-2,4,5-trichlorophenylleucoauramine, 3-diethylamino-7-butylaminofluorane, 3-ethyl-tolylamino-6-methyl-7-anilinofluorane, 3-cyclohexyl-methylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-(β-ethoxyethyl)aminofluorane, 3-diethylamino-6-chloro-7-(γ-chloropropyl)aminofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N-isopentyl-N-ethylamino)-6-methyl-7-anilinofluorane, 3-dibutylamino-7-chloroanilinofluorane, 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-tetrahydrofurylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-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[phenol-3,9'-xanthen-2'-ylamino]phenyl}propane and 3-diethylamino-7-(3'-trifluoromethylphenyl)aminofluorane;Dyes with absorption wavelengths in the near-infrared region include, for example, 3,3-bis[1-(4-methoxyphenyl)-1-(4-dimethylaminophenyl)vinyl-2-yl]-4,5,6,7-tetrachlorophthalide, 3,3-bis[1-(4-methoxyphenyl)-1-(4-pyrrolidinylphenyl)vinyl-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, and 3,6-bis(dimethylamino)fluorene-9-spiro-3'-(6'-dimethylamino)phthalide. Of course, the available leuco dyes are not limited to these compounds, and two or more such compounds can be used in combination as needed.

[0099] There is no particular limitation on the content of the leuco dye, and based on the total solids content of the thermal color-developing printing ink, it is preferably about 15% to 40% by mass, more preferably about 18% to 38% by mass, and even more preferably about 20% to 35% by mass. A leuco dye content of 15% or more by mass can enhance color development ability, thus improving print density, while a leuco dye content of less than 40% by mass can enhance heat resistance.

[0100] Color developing agent

[0101] In this invention, the color developer is selected from at least one of the following groups: N,N'-diarylurea compounds represented by formula (1), compounds represented by formula (2), and 5-(N-3-methylphenyl-aminosulfonyl)-N',N''-bis-(3-methylphenyl)-isophthalic acid diamide. Even when an alcohol is used as a solvent, this improves print density while also achieving excellent transparency, resistance to background fogging, and resistance to plasticizers. Because an alcohol can be used as a solvent, the thermal color-developing printing ink of this invention is suitable for use in gravure printing.

[0102] In formula (1) for N,N'-diarylurea compounds, R 0 C represents 1-12 Alkyl groups can be straight-chain, branched, or alicyclic, and are preferably C12- ... 1-6 Alkyl, and more preferably C 1-3 Alkyl group. C 1-12 Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopentyl, hexyl, cyclohexyl, 2-ethylhexyl, and lauryl. As used herein, "alkyl" also includes C. 1-12 The alkyl moiety of alkoxy groups.

[0103] "Arylalkyl" refers to arylalkyl groups. C 7-12 Examples of aralkyl groups include benzyl, 1-phenylethyl, 2-phenylethyl, and 3-phenylpropyl.

[0104] "Aryl" means a monocyclic or polycyclic ring system radical consisting of a 5- or 6-membered aromatic hydrocarbon ring. C 6-12 Examples of aryl groups include phenyl, 1-naphthyl, and 2-naphthyl. "Aryl" as used herein also includes the aryl portion of aralkyl groups.

[0105] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0106] In formula (1), the plurality of R 0 The substitution position of the -SO3- group can be the same or different. Preferred substitution positions are the 3-position, 4-position, or 5-position, with the 3-position being more preferred. When R 0 C 7-12 The aralkyl group and C 6-12 When the aryl group is substituted, the number of substituents is not particularly limited, and can be, for example, 1 to 4.

[0107] C 1 The C 1-4 The alkyl group can be linear or branched, and examples include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, and tert-butyl.

[0108] The substitution position of the plurality of A 1 The substitution position of the plurality of A

[0109] The N,N'-diaryl urea compound represented by formula (1) is preferably, but not particularly limited to, at least one compound selected from the group consisting of N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(o-toluenesulfonyloxy)phenyl]urea, N,N'-di-[3-(phenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(mesitylenesulfonyloxy)phenyl]urea, N,N'-di-[3-(4-ethylphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(2-naphthalenesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-methoxyphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(benzylsulfonyloxy)phenyl]urea, N,N'-di-[3-(ethanesulfonyloxy)phenyl]urea, N,N'-di-[3-(p-toluenesulfonyloxy)-4-methyl-phenyl]urea, N,N'-di-[4-(p-toluenesulfonyloxy)phenyl]urea, N,N'-di-[4-(phenylsulfonyloxy)phenyl]urea, N,N'-di-[4-(ethanesulfonyloxy)phenyl]urea, and N,N'-di-[2-(p-toluenesulfonyloxy)]phenylurea. Of these, N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea is preferred.

[0110] R 1to R 5 The halogen atom represented can be a fluorine atom, a chlorine atom or a bromine atom, of which a fluorine atom and a chlorine atom are preferred.

[0111] The alkyl group can be linear, branched or cyclic, and is preferably a linear or branched alkyl group, and more preferably a linear alkyl group. Typically, the alkyl group is C 1-12 alkyl, preferably C 1-8 alkyl, more preferably C 1-6 alkyl, and even more preferably C 1-4 alkyl.

[0112] The alkoxy group can be linear, branched or cyclic, and is preferably a linear or branched alkoxy group, and more preferably a linear alkoxy group. Typically, the alkoxy group is C 1-12 alkoxy, preferably C 2-8 alkoxy, more preferably C 2-6 alkoxy, and even more preferably C 2-4 alkoxy.

[0113] The alkylcarbonyloxy group can be linear, branched or cyclic, and is preferably a linear or branched alkylcarbonyloxy group, and more preferably a linear alkylcarbonyloxy group. The alkylcarbonyloxy group is also preferably C 1-10 alkylcarbonyloxy.

[0114] The alkylcarbonylamino group can be linear, branched or cyclic, and is preferably a linear or branched alkylcarbonylamino group, and more preferably a linear alkylcarbonylamino group. The alkylcarbonylamino group is also preferably C 1-10 alkylcarbonylamino.

[0115] The alkylsulfonylamino group can be linear, branched or cyclic, and is preferably a linear or branched alkylsulfonylamino group, and more preferably a linear alkylsulfonylamino group. The alkylsulfonylamino group is also preferably C 1-10 alkylsulfonylamino.

[0116] "Aryl" means a monocyclic or polycyclic ring system group formed from one or more 5- or 6-membered aromatic hydrocarbon rings. Examples of aryl groups include phenyl, naphthyl and biphenyl.

[0117] The aryloxy group is preferably C 6-12 aryloxy. The arylcarbonyloxy group is preferably C 6-12 arylcarbonyloxy. The arylcarbonylamino group is preferably C 6-12 arylcarbonylamino. The arylsulfonylamino group is preferably C 6-12 arylsulfonylamino.

[0118] The monoalkylamino group can be linear, branched or cyclic, and is preferably a linear or branched monoalkylamino group, and more preferably a linear monoalkylamino group. A monoalkylamino group in which the number of carbon atoms of the alkyl group is 1 to 10 is also preferred.

[0119] The dialkylamino group can be linear, branched or cyclic, and is preferably a linear or branched dialkylamino group, and more preferably a linear dialkylamino group. A dialkylamino group in which the number of carbon atoms of the alkyl group is 1 to 10 is also preferred.

[0120] The arylamino group can be a monoarylaminogroup or a diarylaminogroup, and is preferably a C 6-12 monoarylaminogroup.

[0121] Specific examples of the compound represented by formula (2) include those in which R 1 to R 5 each is an alkyl group or a hydrogen atom, preferably R 1 to R 5 each is a C 1-8 linear alkyl group or a hydrogen atom, more preferably R 1 to R 5 each is a C 1-4 linear alkyl group or a hydrogen atom, and even more preferably R 1 to R 5 each is a methyl group or a hydrogen atom.

[0122] Other specific examples of the compound represented by formula (2) include those in which R 1 , R 2 , R 4 and R 5 each is a hydrogen atom, and R 3 is a hydrogen atom, a halogen atom, a nitro group, an amino group, an alkyl group, an alkoxy group, an aryloxy group, an alkylcarbonyloxy group, an alkylcarbonylamino group, an arylcarbonylamino group, an alkylsulfonylamino group, an arylsulfonylamino group, a monoalkylamino group, a dialkylamino group or an arylamino group (preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom or a C 1-8 alkyl group, even more preferably a hydrogen atom or a C 1-4 alkyl group, and particularly preferably a methyl group).

[0123] The position of the substituent bonded to one of the benzene rings in the diphenylurea structure in formula (2) with respect to the aminocarbonyl group on the benzene ring can be ortho, meta or para, preferably ortho or meta, and more preferably meta.

[0124] The compound represented by formula (2) is not particularly limited, and is preferably at least one selected from the group consisting of 3-[(phenylcarbamoyl)amino]phenyl-4-methylbenzenesulfonate, 2-[(phenylcarbamoyl)amino]phenyl-4-methylbenzenesulfonate, and 4-[(phenylcarbamoyl)amino]phenyl-4-methylbenzenesulfonate. Of these, 3-[(phenylcarbamoyl)amino]phenyl-4-methylbenzenesulfonate is preferred.

[0125] The content of the color developer is not particularly limited, and is preferably about 20 to 70 mass%, more preferably about 25 to 62 mass%, and even more preferably about 28 to 55 mass%, based on the total solid content of the heat-sensitive color developing printing ink. A content of the color developer of 20 mass% or more can enhance recording properties and print preservability. A content of the color developer of 70 mass% or less can reduce background fogging.

[0126] Generally, the content of the color developer is preferably 0.5 mass part or more, more preferably 0.8 mass part or more, even more preferably 1 mass part or more, still even more preferably 1.2 mass parts or more, and particularly preferably 1.4 mass parts or more, with respect to 1 mass part of the leuco dye. The content of the color developer is also preferably 10 mass parts or less, more preferably 5 mass parts or less, even more preferably 4 mass parts or less, and particularly preferably 3.5 mass parts or less, with respect to 1 mass part of the leuco dye. A content of the color developer of 0.5 mass part or more can improve recording properties. A content of the color developer of 10 mass parts or less can effectively reduce background fogging in a high-temperature environment.

[0127] Other color-developing agents can be contained as long as the effects of the present application are not impaired. Specific examples of the other color-developing agents include phenol compounds such as 4-tert-butylphenol, 4-acetylphenol, 4-tert-octylphenol, 4,4'-sec-butylidene diphenol, 4-phenylphenol, 4,4'-dihydroxydiphenylmethane, 4,4'-isopropylidene diphenol, 4,4'-cyclohexylidene diphenol, 1,1-bis(4-hydroxyphenyl)-ethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 4,4'-bis(p-tolylsulfonylaminocarbonylamino)diphenylmethane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2'-bis[4-(4-hydroxyphenyl)phenoxy]diethyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-thiobis(3-methyl-6-tert-butylphenol), 4,4'-dihydroxydiphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, 4-hydroxy-4'-n-propoxydiphenyl sulfone, 4-hydroxy-4'-allyloxydiphenyl sulfone, 4-hydroxy-4'-benzyloxydiphenyl sulfone, 3,3'-diallyl-4,4'-dihydroxydiphenyl sulfone, butyl bis(p-hydroxyphenyl)acetate, methyl bis(p-hydroxyphenyl)acetate, hydroquinone monobenzyl ether, bis(3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-allyloxy-4'-hydroxydiphenyl sulfone, 3,4-dihydroxyphenyl-4'-methylphenyl sulfone, 4-hydroxybenzophenone, 4-hydroxydimethyl phthalate, methyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate, sec-butyl 4-hydroxybenzoate, phenyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, benzyl 4-hydroxybenzoate, cresyl 4-hydroxybenzoate, chlorophenyl 4-hydroxybenzoate, and 4,4'-dihydroxydiphenyl ether; aromatic carboxylic acids such as benzoic acid, p-chlorobenzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, salicylic acid, 3-tert-butylsalicylic acid, 3-isopropylsalicylic acid, 3-benzylsalicylic acid, 3-(α-methylbenzyl) salicylic acid, 3,5-di-tert-butylsalicylic acid, 4-[2-(p-methoxyphenoxy)ethoxy]salicylic acid, 4-[3-(p-tolylsulfonyl)propoxy]salicylic acid, 5-[p-(2-p-methoxyphenoxyethoxy)cumyl]salicylic acid, and zinc 4-[3-(p-tolylsulfonyl)propoxy]salicylate; salts of these phenol compounds or aromatic carboxylic acids with, for example, polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel; an antimonyl complex of zinc thiocyanate; complex zinc salts of organic acidic substances such as p-phenylenediaminetricarboxylic acid and other aromatic carboxylic acids;urea compounds such as N-p-tolylsulfonyl-N'-3-(p-tolylsulfonyloxy)phenylurea, N-p-tolylsulfonyl-N'-p-butyloxy carbonylphenylurea, N-p-tolylsulfonyl-N'-phenylurea, 4,4'-bis(p-tolylsulfonylaminocarbonylamino)diphenylmethane, and 4,4'-bis[(4-methyl-3-phenoxy carbonylaminophenyl)ureido]diphenylsulfone; thiourea compounds such as N,N'-di-m-chlorophenylthiourea; organic compounds having -SO2NH- bond in the molecule such as p-cumylphenyl N-(p-tolylsulfonyl)carbamate, p-benzyloxyphenyl N-(p-tolylsulfonyl)carbamate, N-[2-(3-phenylureido)phenyl]benzenesulfonamide, and N-(o-toluoyl)-p-toluenesulfonamide; and inorganic acidic substances such as active clay, attapulgite, colloidal silica, and aluminum silicate; and the like.

[0128] Further, examples include urea carbamate derivatives represented by the following formula (3) such as 4,4'-bis[(4-methyl-3-phenoxy carbonylaminophenyl)ureido]diphenylsulfone, 4,4'-bis[(2-methyl-5-phenoxy carbonylaminophenyl)ureido]diphenylsulfone, and 4-(2-methyl-3-phenoxy carbonylaminophenyl)ureido-4'-(4-methyl-5-phenoxy carbonylaminophenyl)ureidodiphenylsulfone; and diphenylsulfone derivatives represented by the following formula (4); and the like. Of course, the color developer usable is not limited to these compounds, and two or more such compounds can be used in combination as needed.

[0129]

[0130]

[0131] (In the formula, n represents an integer of 1 to 6.)

[0132] Binder

[0133] The heat-sensitive color developing printing ink of the present application contains a vinylpyrrolidone-vinyl acetate copolymer as a binder. This enhances the color developing ability, improves the print density, and increases the plasticizer resistance.

[0134] The molar ratio of vinylpyrrolidone to vinyl acetate (vinylpyrrolidone / vinyl acetate) in the vinylpyrrolidone-vinyl acetate copolymer is not particularly limited, and is preferably 50 / 50 to 30 / 70, and more preferably 40 / 60 to 30 / 70. The molar ratio of vinylpyrrolidone to vinyl acetate of 50 / 50 to 30 / 70 can improve the print density.

[0135] The content of the vinylpyrrolidone-vinyl acetate copolymer is not particularly limited, and is preferably about 5 to 35 mass%, more preferably about 9 to 33 mass%, and even more preferably about 12 to 28 mass%, based on the total solid content of the thermally sensitive color developing printing ink. A content of the vinylpyrrolidone-vinyl acetate copolymer of 5 mass% or more can improve adhesion to a substrate. A content of the vinylpyrrolidone-vinyl acetate copolymer of 35 mass% or less can enhance recording properties.

[0136] The thermally sensitive color developing printing ink of the present application can contain other binders as long as they do not impair the effects of the present application. Such other binders used can be, for example, water-based binders as water-soluble binders or water-dispersible binders. Examples of the water-soluble binders include polyvinyl alcohol; modified polyvinyl alcohol such as carboxyl-modified polyvinyl alcohol, acetyl acetyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, and silicon-modified polyvinyl alcohol; starch and its derivatives; cellulose derivatives such as methoxycellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, methylcellulose, and ethylcellulose; sodium polyacrylate, polyvinylpyrrolidone, polyamide, diisobutylene-maleic anhydride copolymer salt, styrene-acrylic acid copolymer salt, styrene-maleic anhydride copolymer salt, ethylene-maleic anhydride copolymer salt, acrylamide-acrylate copolymer, acrylamide-acrylate-methacrylic acid copolymer, polyacrylamide, sodium alginate, gelatin, casein, and gum arabic. Examples of the water-dispersible binders include emulsions of polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-vinyl acetate copolymer, and the like; and latexes of water-insoluble polymers such as styrene-butadiene copolymer or styrene-butadiene-acrylic acid-based copolymer. Furthermore, for example, an organic solvent-soluble type binder can be used as the binder. Examples of the organic solvent-soluble type binder include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, polyurethane, saturated polyester, polyester polyurethane, epoxy resin, phenoxy resin, nitrocellulose, melamine resin, chlorinated polyethylene, and chlorinated polypropylene. These binders can be used alone or in combination of two or more types.

[0137] Colloidal silica

[0138] In the present application, the thermosensitive color developing printing ink can further contain colloidal silica having an average particle diameter of 45 nm or less. This can enhance the color developing ability without impairing the transparency, thereby improving the print density. The average particle diameter of the colloidal silica is preferably 60 nm or less, and more preferably 45 nm or less. However, an average particle diameter of 5 nm or more is preferable from the viewpoint of heat resistance. As used herein, the "average particle diameter" means the median diameter based on volume measured by the BET method, the Sears method, or laser diffraction. More simply, the individual particle diameters can be measured from a particle image (SEM image) using an electron microscope, and the average value of 10 particles can be used as the average particle diameter.

[0139] The content of the colloidal silica having an average particle diameter of 45 nm or less is not particularly limited, and is preferably about 5 to 30 mass%, more preferably about 7 to 28 mass%, and even more preferably about 10 to 25 mass%, based on the total solid content of the thermosensitive color developing printing ink. A content of 5 mass% or more of the colloidal silica can improve the strength of the coating film. A content of 30 mass% or less of the colloidal silica can maintain the transparency.

[0140] Solvent

[0141] The thermosensitive color developing printing ink of the present application can contain a solvent. Examples of such a solvent include water, alcohol, toluene, cyclohexane, and methylcyclohexane, of which a solvent containing water and alcohol is preferable. As the alcohol, an alcohol having 5 or less carbon atoms is desirable, and examples of such an alcohol having 5 or less carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, t-butanol, and n-pentanol. The use of alcohol in the solvent makes the ink usable for gravure printing.

[0142] Stabilizer

[0143] In the present application, the heat-sensitive color developing printing ink can further contain a stabilizer, mainly to further improve the preservability of the developed image. The stabilizer used can be at least one compound selected from the group consisting of phenol compounds such as 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,1-bis(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisphenol, and 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisphenol; epoxy compounds such as 4-benzyloxyphenyl-4'-(2-methyl-2,3-epoxypropyloxy)phenylsulfone, 4-(2-methyl-1,2-epoxyethyl)diphenylsulfone, and 4-(2-ethyl-1,2-epoxyethyl)diphenylsulfone; and isocyanuric acid compounds such as 1,3,5-tris(2,6-dimethylbenzyl-3-hydroxy-4-tert-butyl)isocyanuric acid. Of course, the stabilizer usable is not limited to these compounds, and two or more such compounds can also be used in combination as needed.

[0144] When a stabilizer is used, the amount thereof can be an effective amount for improving the image preservability. The stabilizer is generally preferably used in an amount of about 1 to 30 mass%, and more preferably about 5 to 20 mass%, based on the total solid content of the heat-sensitive color developing printing ink.

[0145] Sensitizer

[0146] The heat-sensitive color developing printing ink in the present application can also contain a sensitizer. The use of a sensitizer enhances recording sensitivity. Examples of usable sensitizers include stearic acid amide, methoxycarbonyl-N-stearic acid benzamide, N-benzoyl stearic acid amide, N-eicosanoic acid amide, ethylene bis-stearic acid amide, behenic acid amide, methylene bis-stearic acid amide, N-hydroxymethyl stearic acid amide, dibenzyl terephthalate, dimethyl terephthalate, dioctyl terephthalate, diphenyl sulfone, benzyl p-benzyloxybenzoate, benzyl 1-hydroxy-2-naphthoate, 2-naphthyl benzyl ether, m-terphenyl, p-benzyl biphenyl, di-p-chlorobenzyl oxalate, di-p-methylbenzyl oxalate, dibenzyl oxalate, p-tolyl biphenyl ether, di(p-methoxyphenoxyethyl) ether, 1,2-di(3-methoxyphenoxy)ethane, 1,2-di(4-methoxyphenoxy)ethane, 1,2-di(4-methoxyphenoxy)ethane, 1,2-di(4-chlorophenoxy)ethane, 1,2-diphenoxyethane, 1-(4-methoxyphenoxy)-2-(3-methylphenoxy)ethane, p-methylthiophenyl benzyl ether, 1,4-di(phenylthio)butane, p-methylacetanilide, p-ethoxyacetanilide, N-acetylacetophenyl-p-toluidine, 1,2-diphenoxy methylbenzene, di(β-biphenylylethoxy)benzene, p-bis(vinyloxyethoxy)benzene, 1-isopropylphenyl-2-phenylethane, di-o-chlorobenzyl adipate, 1,2-di(3,4-dimethylphenyl)ethane, 1,3-di(2-naphthoxy)propane, biphenyl, and benzophenone, and the like. These sensitizers can be used in combination, provided that the combination does not impair the effects of the present application. The content of the sensitizer can be an effective amount for sensitization, and is generally preferably about 2 to 40 mass%, and more preferably about 5 to 25 mass%, based on the total solid content of the heat-sensitive color developing printing ink.

[0147] For other components constituting the heat-sensitive color developing printing ink, for example, the following can be optionally used: a crosslinking agent, a wax, a metal soap, a water resistance agent, a pigment, a dispersing agent, a colored dye, and a fluorescent dye.

[0148] Crosslinking agent

[0149] The heat-sensitive color developing printing ink can contain a crosslinking agent for curing the binder in the heat-sensitive recording layer or other layer. This can improve the water resistance of the heat-sensitive recording layer. Examples of the crosslinking agent include aldehyde-based compounds such as glyoxal, polyamine-based compounds such as polyethyleneimine, epoxy compounds, polyamide resins, melamine resins, glyoxalate, dimethylol urea compounds, aziridine compounds, blocked isocyanate compounds; inorganic compounds such as ammonium persulfate, ferric chloride, magnesium chloride, sodium tetraborate, and potassium tetraborate; boric acid, boric acid triester, boron-based polymers, hydrazide compounds, and glyoxalate. These can be used alone or in combination of two or more types. The preferable amount of the crosslinking agent per 100 parts by mass of the total solid content of the heat-sensitive color developing printing ink is about 1 part by mass to 10 parts by mass. This can improve the water resistance of the heat-sensitive recording layer.

[0150] Wax

[0151] Examples of the wax include waxes such as paraffin wax, carnauba wax, microcrystalline wax, polyolefin wax, and polyethylene wax; higher fatty acid amides such as stearamide and ethylene bis-stearamide; higher fatty acid esters; and derivatives thereof.

[0152] Metal soap

[0153] Examples of the metal soap include higher fatty acid polyvalent metal salts such as zinc stearate, aluminum stearate, calcium stearate, and zinc oleate. In addition, the heat-sensitive color developing printing ink can optionally contain various auxiliary agents such as oil repellents, defoaming agents, and viscosity modifiers to the extent that the effects of the present application are not impaired.

[0154] The heat-sensitive color developing printing ink of the present application is generally prepared using water and alcohol as solvents by dispersing the leuco dye and the color developer, optionally together with the binder, the sensitizer, and the stabilizer, or separately, by using stirring and a wet-type grinder such as a ball mill, a CoBall mill, a mortar, or a vertical and horizontal sand mill to form a dispersion liquid, and then optionally mixing the thus-prepared dispersion liquid with the binder and the auxiliary agent to have an average particle diameter of 2 μm or less.

[0155] The heat-sensitive color developing printing ink of the present application can be used for forming a heat-sensitive recording layer of a heat-sensitive recording body on at least a part of one surface or both surfaces of a support. The method of forming the heat-sensitive recording layer is preferably but not particularly limited to a printing method such as gravure printing.

[0156] Protective layer printing ink for thermosensitive recording body

[0157] Binder

[0158] The protective layer printing ink of the present application contains a polyvinyl acetal resin as a binder. This can improve print preservability (particularly plasticizer resistance) and thermal head matching (particularly head residue suitability), while also enhancing transparency.

[0159] The polyvinyl acetal resin can be produced according to, for example, a method in which polyvinyl alcohol is reacted with an aldehyde to acetalize it. Examples of the aldehyde include, but are not particularly limited to, formaldehyde (including paraformaldehyde), acetaldehyde (including triacetaldehyde), propionaldehyde, butyraldehyde, valeraldehyde, hexaldehyde, heptaldehyde, 2-ethylhexaldehyde, cyclohexaldehyde, furfural, glyoxal, glutaraldehyde, benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, and β-phenylpropionaldehyde.

[0160] Examples of the polyvinyl acetal resin include a polyvinyl butyral resin in which the acetal group is a butyl acetal group, and a polyvinyl acetyl acetal resin in which the acetal group is an acetyl acetal group.

[0161] The number average molecular weight of such a polyvinyl acetal resin is preferably 17,000 to 40,000, more preferably 17,000 to 32,000, and even more preferably 17,000 to 27,000. A polyvinyl acetal resin having a number average molecular weight of 17,000 can improve print preservability (particularly plasticizer resistance) and thermal head matching (particularly head residue suitability). A polyvinyl acetal resin having a number average molecular weight of 40,000 or less can increase the concentration of the protective layer ink. The "number average molecular weight" in the present application refers to the number average molecular weight analyzed by gel permeation chromatography (GPC).

[0162] The content of such a polyvinyl acetal resin is not particularly limited, and is preferably about 75 mass% to 99 mass%, more preferably about 75 mass% to 90 mass%, and even more preferably about 80 mass% to 85 mass%, based on the total solid content of the protective layer printing ink. A content of 75 mass% or more of the polyvinyl acetal resin can improve print preservability (particularly plasticizer resistance). A content of 99 mass% or less of the polyvinyl acetal resin can improve thermal head matching (particularly adhesion).

[0163] The protective layer printing ink of the present application can contain other binders as long as they do not impair the effects of the present application. Such other binders used can be, for example, water-based binders as water-soluble binders or water-dispersible binders. Examples of the water-soluble binders include polyvinyl alcohol; modified polyvinyl alcohol such as carboxyl-modified polyvinyl alcohol, acetylacetone-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, and silicon-modified polyvinyl alcohol; starch and its derivatives; cellulose derivatives such as methoxycellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, methylcellulose, and ethylcellulose; polyvinylpyrrolidone; polyamide; diisobutylene-maleic anhydride copolymer salt; styrene-maleic anhydride copolymer salt; sodium alginate; gelatin; casein; and gum arabic. Examples of the water-dispersible binders include emulsions of polyvinyl acetate, polyurethane, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, ethylene-vinyl acetate copolymer, and the like; and latexes of water-insoluble polymers such as styrene-butadiene copolymer. In addition, for example, an organic solvent-soluble type binder can be used as the additional binder. Examples of the organic solvent-soluble type binder include vinyl acetate resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer resin, vinylpyrrolidone-vinyl acetate copolymer resin, butyral resin, polyester resin, nitrocellulose resin, and styrene resin. These binders can be used alone or in combination of two or more types.

[0164] Slip property imparting agent

[0165] The protective layer printing ink of the present application contains an alkyl phosphate ester and / or a salt thereof as a slip imparting agent. This can improve the thermal head matching property (particularly, head residue applicability) as well as enhance the transparency.

[0166] The alkyl phosphate ester is a compound in which at least one hydrogen atom of the three hydroxyl groups of phosphoric acid is substituted with an alkyl group. In particular, a mixture of monoester (monoalkyl phosphate ester) and diester forms is preferable. The number of carbon atoms in the alkyl group of the ester moiety in the alkyl phosphate ester is preferably 12 to 36, more preferably 12 to 30, and even more preferably 12 to 22. The alkyl group can be linear or branched.

[0167] Examples of the alkyl phosphate ester salt include inorganic salts, organic amine salts, and basic amino acid salts. Examples of the inorganic salts include alkali metal salts such as sodium salts and potassium salts; alkaline earth metal salts such as magnesium salts and calcium salts; ammonium salts; aluminum salts; and zinc salts. Examples of the organic amine salts include monoethanolamine salts, diethanolamine salts, and triethanolamine salts. Examples of the basic amino acid salts include arginine salts and lysine salts. The alkyl phosphate ester salt is preferably in the Na-neutralized or Ca-neutralized form.

[0168] The first acid value of the alkyl phosphate ester is not particularly limited, and is preferably 135 mgKOH / g or less, more preferably 120 mgKOH / g or less, and even more preferably 100 mgKOH / g or less. The alkyl phosphate ester having a first acid value of 135 mgKOH / g or less can improve the background fog resistance. The first acid value is measured according to the neutralization titration method or the potentiometric method.

[0169] The content of such alkyl phosphate ester and / or salt thereof is not particularly limited, and is preferably about 1 to 25 mass%, more preferably about 1 to 20 mass%, and even more preferably about 3 to 10 mass%, based on the total solid content of the overcoat printing ink. The content of the alkyl phosphate ester and / or salt thereof of 1 mass% or more can improve the hot head matching property (sliding property, reduction of printing noise). The content of the alkyl phosphate ester and / or salt thereof of 25 mass% or less can enhance the printing storage property (plasticizer resistance).

[0170] The overcoat printing ink of the present application can contain other sliding property-imparting agents, as long as they do not impair the effects of the present application. Examples of the other sliding property-imparting agents include metal salts of higher fatty acids, such as zinc stearate and calcium stearate, and waxes, such as paraffin wax, oxidized paraffin wax, polyethylene, oxidized polyethylene, and castor wax. These sliding property-imparting agents can be used alone or in combination of two or more types.

[0171] Calcined kaolin

[0172] In the present application, the overcoat printing ink can further contain calcined kaolin having an average particle diameter of 2.0 μm or less. This can improve the hot head matching property (particularly, head residue applicability). The average particle diameter of the calcined kaolin is preferably 1.5 μm or less, and more preferably 1.3 μm or less. From the viewpoint of the hot head cleaning performance, the average particle diameter of the calcined kaolin is preferably 0.1 μm or more. As used herein, the "average particle diameter" means the median diameter based on volume as measured according to the BET method, the Sears method, or laser diffraction. More simply, the individual particle diameters can be measured from a particle image (SEM image) using an electron microscope, and the average of 10 particles can be used as the average particle diameter.

[0173] The content of the calcined kaolin having an average particle diameter of 2.0 μm or less is not particularly limited, and is preferably about 0.5 to 10 mass%, more preferably about 0.5 to 7.0 mass%, and even more preferably about 1.0 to 5.0 mass%, based on the total solid content of the overcoat printing ink. The content of such calcined kaolin of 0.5 mass% or more can improve the hot head matching property (particularly, head residue applicability). The content of such calcined kaolin of 10 mass% or less can reduce the abrasion property of the hot head protective film.

[0174] Solvent

[0175] The protective layer printing ink of the present application can contain a solvent. Examples of such solvents include water, alcohols, cycloalkanes, toluene, and methylcyclohexane, of which solvents containing alcohols and cycloalkanes are preferred. The alcohol is preferably an alcohol having 5 or less carbon atoms. Examples of such alcohols having 5 or less carbon atoms include methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, t-butanol, and n-pentanol. Examples of cycloalkanes include cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane, cyclodecane, methylcyclohexane, methylcyclooctane, dimethylcyclohexane, and ethylcyclohexane. The use of an alcohol in the solvent makes the ink usable for gravure printing.

[0176] Other optional component materials for the protective layer printing ink used include cross-linking agents and pigments.

[0177] Crosslinking agent

[0178] The protective layer printing ink can contain a cross-linking agent for curing the binder in the protective layer or other layer. This can improve the water resistance of the protective layer. Examples of cross-linking agents include aldehyde-based compounds such as glyoxal, polyamine-based compounds such as polyethyleneimine, epoxy compounds, polyamide resins, melamine resins, glyoxalate salts, dimethylol urea compounds, aziridine compounds, blocked isocyanate compounds; inorganic compounds such as ammonium persulfate, ferric chloride, magnesium chloride, sodium tetraborate, and potassium tetraborate; boric acid, boric acid triesters, boron-based polymers, hydrazide compounds, and glyoxalate salts. These can be used alone or in combination of two or more types. The preferred amount of cross-linking agent per 100 parts by mass of the total solid content of the protective layer printing ink is about 1 to 10 parts by mass. This can improve the water resistance of the protective layer.

[0179] Pigment

[0180] Examples of pigments contained in the protective layer include, but are not limited to, inorganic pigments such as amorphous silica, kaolin, clay, light calcium carbonate, heavy calcium carbonate, titanium oxide, magnesium carbonate, aluminum hydroxide, colloidal silica, and synthetic stratified mica, and plastic pigments such as urea-formalin resin fillers. The content of the pigment is preferably about 1 to 20 mass% and more preferably about 1 to 10 mass% based on the total solid content in the protective layer.

[0181] The protective layer printing ink of the present application is generally prepared by using an alcohol and a cycloalkane as a solvent, and by mixing a binder and a slip imparting agent, optionally with an auxiliary.

[0182] The protective layer printing ink of the present application can be used to form a protective layer of a heat-sensitive recording body on at least a part of one surface or both surfaces of a support. The method of forming the protective layer is preferably, but not particularly limited to, a printing method such as gravure printing.

[0183] Support

[0184] The support in the present application is not particularly limited in type, shape, size, etc., and can be appropriately selected and used from, for example, high-grade paper (acid paper and neutral paper), medium-grade paper, coated paper, art paper, cast-coated paper, glassine paper, resin-laminated paper, polyolefin-based synthetic paper, synthetic fiber paper, nonwoven fabric, cellophane, synthetic resin film, and various other transparent supports. Among them, a translucent or transparent support made of glassine paper or laminated resin paper, or a transparent film made of cellophane or synthetic resin film is preferred. This ensures the enhancement of transparency in the non-printing area of the heat-sensitive recording body. Examples of the resin used for the laminated resin paper or synthetic resin film include polyester-based resins such as polyethylene terephthalate (PET), and polyolefin-based resins such as polypropylene (PP) and polyethylene (PE). The thickness of the support is not particularly limited, and is generally about 5 μm to 200 μm. The density of the support is also not particularly limited, and is preferably about 0.60 g / cm 3 to 2.00 g / cm 3 .

[0185] Thermosensitive recording layer

[0186] The heat-sensitive recording body can optionally include a heat-sensitive recording layer on the support. The heat-sensitive recording layer is generally formed on the support by printing using a heat-sensitive color developing printing ink. In the present application, it is preferred that the heat-sensitive recording layer is provided on at least a part of one surface or both surfaces of the support, and is a layer formed by using the heat-sensitive color developing printing ink of the present application. When the heat-sensitive color developing printing ink of the present application is not used, the heat-sensitive color developing ink described in the section of "heat-sensitive color developing printing ink" can be used, and there is no limitation on the color developer and the binder. The coating amount of the heat-sensitive recording layer is not particularly limited, and is preferably about 1 g / m 2 to 12 g / m 2 , more preferably about 2 g / m 2 to 10 g / m 2 , even more preferably about 2.5 g / m 2 to 8 g / m 2 , and particularly preferably about 3 g / m 2 to 5.5 g / m 2 . Furthermore, the heat-sensitive recording layer can be formed into two or more layers as needed, and the composition and the coating amount of each layer can be the same or different.

[0187] Protective layer

[0188] The heat-sensitive recording body can optionally include a protective layer on the support or the heat-sensitive recording layer. The protective layer is usually formed on the support or the heat-sensitive recording layer by printing using the protective layer printing ink for heat-sensitive recording body of the present application. In the present application, it is preferred that the protective layer is provided on at least a part of one surface or both surfaces of the support, and is a layer formed using the protective layer printing ink for heat-sensitive recording body of the present application. When the protective layer printing ink for heat-sensitive recording body of the present application is not used, the protective layer printing ink for heat-sensitive recording body described in the section of "Protective layer printing ink for heat-sensitive recording body" can be used without limitation to the binder and the slip imparting agent. The coating amount of the protective layer is not particularly limited, and is preferably about 0.3 g / m2to 15 g / m2, more preferably about 0.3 g / m2to 10 g / m2, still more preferably about 0.3 g / m2to 8 g / m2, even more preferably about 0.5 g / m2to 8 g / m2, particularly preferably about 0.5 g / m2to 5 g / m2, and still more preferably about 0.5 g / m2to 3 g / m2, in terms of dry mass. Furthermore, the protective layer can be formed into two or more layers as needed, and the composition and the coating amount of each layer can be the same or different. 2 to 15 g / m 2 , more preferably about 0.3 g / m 2 to 10 g / m 2 , even more preferably about 0.3 g / m 2 to 8 g / m 2 , particularly preferably about 0.5 g / m 2 to 8 g / m 2 , and still more preferably about 0.5 g / m 2 to 5 g / m 2 Furthermore, the protective layer can be formed into two or more layers as needed, and the composition and the coating amount of each layer can be the same or different.

[0189] Undercoat layer

[0190] The heat-sensitive recording body of the present application can also optionally include a primer layer between the support and the heat-sensitive recording layer. The primer layer preferably contains a binder.

[0191] Binder

[0192] The binder contained in the undercoat layer is not particularly limited, and can be an aqueous binder as a water-soluble binder or a water-dispersible binder, or a solvent-based binder. Examples of the binder include water-soluble polymeric materials such as polyvinyl alcohol, derivatives thereof, starch, derivatives thereof, cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, and ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide-acrylate copolymer, acrylamide-acrylate-methacrylate copolymer, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, casein, gelatin, and derivatives thereof; emulsions such as polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, chlorovinyl-vinyl acetate copolymer, polybutyl methacrylate, and ethylene-vinyl acetate copolymer; and water-insoluble polymers such as latex of styrene-butadiene copolymer and styrene-butadiene-acryl copolymer. These can be appropriately used on a support such as a polyester-based film (e.g., a PET film) and a polyester-based laminated resin paper. Among them, a binder containing latex is preferably used. In addition, examples of the aqueous binder or the solvent-based binder include chlorinated polyolefin resin. The chlorinated polyolefin resin can be preferably used on a support such as a polyolefin-based film such as a PP film, a paper such as a polyolefin-based synthetic paper, a polyolefin-based resin laminated paper, and glassine, and cellophane. The content of the binder can be selected from a wide range; generally, the content of the binder is preferably about 10 to 100 mass% and more preferably about 15 to 60 mass% based on the total solid content in the undercoat layer.

[0193] It is preferable that the binder contain a binder resin having a glass transition temperature (Tg) of -10°C or lower. The binder resin having a glass transition temperature of -10°C or lower can improve the image quality even in a low energy region. The glass transition temperature is preferably -30°C or lower because the image quality can be further improved in a low energy region. However, since undesirable adhesion occurs at a temperature of -50°C or lower, the glass transition temperature is preferably -40°C or higher.

[0194] The undercoat layer can contain at least one pigment selected from the group consisting of an oil absorption pigment having an oil absorption amount of 70 ml / 100 g or more, and particularly about 80 to 150 ml / 100 g, an organic hollow particle, and a thermally expandable particle. The "oil absorption amount" refers to a value determined according to the method described in JIS K 5101.

[0195] The oil-absorbing pigments used can be selected from various types. Specific examples include inorganic pigments such as calcined kaolin, amorphous silica, light calcium carbonate, and talc. The average particle size of the primary particles of the oil-absorbing pigment is preferably from about 0.01 μm to 5 μm, and particularly preferably from about 0.02 μm to 3 μm. The amount of oil-absorbing pigment used can be selected from a wide range; generally, the amount of oil-absorbing pigment based on the total solids content in the base coat is preferably from about 20% to 80% by mass, and more preferably from about 25% to 75% by mass.

[0196] For example, a primer coating liquid is prepared by mixing an adhesive, hollow particles, pigments, and additives with water as a medium. This primer coating liquid is then applied to a support, and the liquid is allowed to dry to form a primer coating on the support. The primer coating can also be formed in the same manner as a thermal recording layer, using a printing method such as gravure printing. The coating amount of the primer coating liquid, on a dry weight basis, is preferably, but not particularly limited to, about 2 g / m³. 2 Up to 20g / m 2 And more preferably about 2g / m 2 Up to 12g / m 2 .

[0197] Examples of additives included in the coating liquid for the primer layer include dispersants such as sodium dioctyl sulfosuccinate, sodium dodecylbenzene sulfonate, sodium lauryl sulfate, and metal salts of fatty acids; waxes such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester waxes; hydration resistant agents such as hydrazide compounds, boric acid, dialdehyde starch, glyoxylate, and epoxy compounds; defoamers; coloring dyes; and fluorescent dyes.

[0198] Heat-seal layer

[0199] The thermal recording device of the present invention may optionally include a heat-sealing layer on at least a portion of one or both surfaces of the support. Preferably, the heat-sealing layer is located on the surface of the support opposite to the surface on which the thermal recording layer is located.

[0200] The heat-sealing layer of this invention includes a single-layer film composed of a single resin and a single-layer or laminated film using multiple resins. Preferred examples of resins constituting the heat-sealing layer include polyolefin resins (especially polyethylene and polypropylene), polystyrene resins, polyester resins (especially polyethylene terephthalate resins), polyamide resins (especially nylon), and biodegradable resins.

[0201] Polyethylene can be low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), or high-density polyethylene (HDPE).

[0202] The heat-seal layer can be non-oriented, or uniaxially or biaxially oriented.

[0203] The thickness of the heat-seal layer is not particularly limited; the thickness is preferably about 10 μm to 70 μm, more preferably about 20 μm to 60 μm, and even more preferably about 30 μm to 50 μm.

[0204] The heat-seal layer can contain additives such as fillers, anti-blocking agents, antistatic agents, plasticizers, and oxidizing agents. These additives can be used alone or in combination of two or more.

[0205] The heat-seal layer can be formed by extruding the resin onto the support to laminate it, or by adhering the support and the heat-seal layer using an adhesive.

[0206] The adhesive used for the adhesion is not particularly limited; the adhesive can be any solventless type, organic solvent type, or water-based type adhesive.

[0207] Examples of the main component constituting the adhesive include (meth)acrylate copolymer, α-olefin copolymer, ethylene-vinyl acetate copolymer, polyvinyl alcohol, polyurethane, styrene-butadiene copolymer, polyvinyl chloride, epoxy resin, melamine resin, silicone resin, natural rubber, casein, and starch.

[0208] After the adhesive is applied to the heat-seal layer, the heat-seal layer and the support can be laminated. Alternatively, after the adhesive is applied to the support, the support and the heat-seal layer can be laminated. Alternatively, after the adhesive is applied to both the heat-seal layer and the support, the heat-seal layer and the support can be laminated. There is no particular limitation in this regard.

[0209] The method of applying the adhesive can be appropriately selected from known methods without particular limitation. Examples include roll coating, die coating, and spray coating.

[0210] The application amount of the adhesive is not particularly limited. The application amount (coating amount) after drying is preferably 0.5 g / m 2 or more, more preferably 1.0 g / m 2 or more, and even more preferably 1.5 g / m 2 or more, and preferably 10.0 g / m 2 or more, more preferably 7.0 g / m 2 or more, and even more preferably 5.0 g / m 2 or more.

[0211] Printing layer

[0212] In the present application, a print layer can be provided on at least one of the following: on the protective layer, between the heat-sensitive recording layer and the protective layer, on the heat-sensitive recording layer, between the support and the heat-seal layer, and on the surface of the support opposite to the surface on which the heat-sensitive recording layer is present. The print ink for forming the print layer, based on classification by print plate type, includes inks for letterpress printing, lithographic printing, gravure printing, and hole plate printing. The print ink for forming the print layer, based on classification by drying form, includes inks for permeation drying, evaporation drying, oxidative polymerization drying, and photopolymerization drying (UV-curing type). In order to form the print layer, various printing methods such as flexographic printing, offset printing, gravure printing, and screen printing can be used. Non-plate digital printing methods such as on-demand printing and direct printing can also be used. The color tone of the print ink is not particularly limited; however, in particular when heat-sensitive recording is performed on a portion corresponding to the print layer, it is preferable that the optical density of the print layer be lower than the optical density of the recording portion of the heat-sensitive recording layer. The print pattern can be partial printing or full-surface solid printing. It preferably has a watermarked background print having an optical density of about 0.1 to 0.6, or fixed information that does not interfere with heat-sensitive recording. For example, when the heat-sensitive recording body is used as a top-seal cover material on which variable information such as product name, expiration date, and bar code is recorded by heat-sensitive recording, it is preferable that the area on the back surface of the heat-sensitive recording corresponding to these be partially printed with white ink on the surface of the support opposite to the surface on which the heat-sensitive recording layer is present. This results in improved readability of the bar code or the like.

[0213] Thermosensitive recording body

[0214] The heat-sensitive recording body can be produced by forming the layers on the support. The method of forming the layers on the support can be any printing method such as gravure printing, and known coating methods such as air knife method, blade method, gravure method, roll coater method, spray method, dip method, bar method, curtain method, slot die method, slide die method, or extrusion method. The method is preferably gravure printing or other printing method, and more preferably gravure printing. The respective coating materials can be applied and dried to form the respective layers, or the same coating material can be applied in two or more separate layers. Furthermore, simultaneous multilayer coating in which two or more layers are simultaneously applied can also be performed. After the respective layers are formed or after all of the layers are formed, a smoothing treatment can be performed at any stage using a known method such as supercalendering or soft calendering.

[0215] The method of recording an image on the heat-sensitive recording body of the present application is not particularly limited, and can be appropriately selected depending on the intended use. Examples of the available method of recording an image include thermal head printers and lasers (e.g., carbon dioxide lasers, UV lasers, semiconductor lasers, YAG lasers, fiber lasers, solid-state lasers, and dye lasers). The wavelength of the laser used is not particularly limited, and can be appropriately selected depending on the intended use.

[0216] The heat-sensitive recording body of the present application has high transparency, and exhibits excellent resistance to background fogging and resistance to plasticizers, and is thus suitable for use in food applications, such as labels for transparent containers of salads and prepared foods, and lid materials for top sealing. In the lid materials for top sealing, although the opacity can increase due to the heat-sensitive color-developing printing ink on the printed surface and the white ink printed on the back surface, the heat-sensitive recording body of the present application can provide increased surface transparency, thereby allowing the contents to be observed through the lid material while confirming information such as the raw materials of the contents, and the like. Furthermore, the use of the heat-sensitive recording body as the lid material for top sealing eliminates the need to attach a heat label, improving the packaging efficiency while reducing plastic consumption.

[0217] Examples

[0218] The present application is described in more detail below with reference to Examples. However, the present application is not limited to these. Unless otherwise specified, "parts" and "%" refer to "mass parts" and "mass%", respectively. The particle diameter, including the average particle diameter, is a value measured using an LB500 laser diffraction particle size distribution analyzer (manufactured by Horiba, Ltd.). The "average particle diameter" refers to the median diameter (D50).

[0219] A. Thermosensitive recording body (A)

[0220] Example A1

[0221] (1) Preparation of a dye dispersion liquid (A liquid)

[0222] A mixture of 3-di(n-butyl)amino-6-methyl-7-anilinofluoran 30 parts, a 50% isopropyl alcohol solution of a vinylpyrrolidone-vinyl acetate copolymer having a molar ratio of vinylpyrrolidone / vinyl acetate of 30 / 70 13 parts, water 44.5 parts, and isopropyl alcohol 12.5 parts was ground using a sand mill (Sand Grinder, manufactured by Aimex Co., Ltd.) until an average particle diameter of 0.15 μm was achieved, thereby obtaining a dye dispersion liquid (A liquid).

[0223] (2) Preparation of a color developer dispersion liquid (B liquid)

[0224] N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea 30 parts, a 50% isopropyl alcohol solution of a vinylpyrrolidone-vinyl acetate copolymer having a molar ratio of vinylpyrrolidone / vinyl acetate of 30 / 70 13 parts, water 44.5 parts, and isopropyl alcohol 12.5 parts were mixed, and ground using a sand grinder (manufactured by Aimex Co., Ltd.) until an average particle diameter of 0.15 μm was achieved, thereby obtaining a color developer dispersion liquid (B liquid).

[0225] (3) Preparation of a thermosensitive color developing printing ink

[0226] 10 parts of the A liquid, 20 parts of the B liquid, 3.5 parts of water, and 3 parts of isopropyl alcohol were mixed and stirred, thereby obtaining a thermosensitive color developing printing ink.

[0227] (4) Preparation of a thermosensitive recording body

[0228] A five-color gravure printing machine was used to print on one surface of a transparent PET film having a thickness of 12 μm with the thermosensitive color developing printing ink so that the coated amount of the thermosensitive color developing printing ink after drying was 3.5 g / m 2 , and the film was wound to form a thermosensitive recording layer. Further, an ester-based adhesive was applied in an amount of 3 g / m 2 on a surface opposite to the surface on which printing was performed with the thermosensitive color developing printing ink by a dry lamination method, and a low-density polyethylene film having a thickness of 30 μm was adhered to obtain a thermosensitive recording body having a heat-seal layer. The obtained thermosensitive recording body was wound into a small roll using a slitting machine, and further cut into a predetermined shape to prepare a lid material for top sealing, which was then subjected to a sealing process and used for sealing a food packaging container.

[0229] Example A2

[0230] A thermosensitive recording body was obtained in the same manner as in Example Al except that in the preparation of the A liquid and the B liquid in Example Al, the amount of the 50% isopropyl alcohol solution of a vinylpyrrolidone-vinyl acetate copolymer was changed from 13 parts to 6 parts.

[0231] Example A3

[0232] A thermosensitive recording body was obtained in the same manner as in Example Al except that in the preparation of the A liquid and the B liquid in Example Al, the amount of the 50% isopropyl alcohol solution of a vinylpyrrolidone-vinyl acetate copolymer was changed from 13 parts to 25 parts, and in the preparation of the thermosensitive color developing printing ink, the amount of the B liquid was changed from 20 parts to 40 parts.

[0233] Example A4

[0234] A heat-sensitive recording material was obtained in the same manner as in Example Al except that, in the preparation of the A liquid and the B liquid in Example Al, a vinylpyrrolidone-vinyl acetate copolymer having a molar ratio of vinylpyrrolidone to vinyl acetate of 70 / 30 was used instead of a vinylpyrrolidone-vinyl acetate copolymer having a molar ratio of vinylpyrrolidone to vinyl acetate of 30 / 70.

[0235] Example A5

[0236] A heat-sensitive recording material was obtained in the same manner as in Example Al except that, in the preparation of the A liquid and the B liquid in Example Al, a vinylpyrrolidone-vinyl acetate copolymer having a molar ratio of vinylpyrrolidone to vinyl acetate of 70 / 30 was used instead of a vinylpyrrolidone-vinyl acetate copolymer having a molar ratio of vinylpyrrolidone to vinyl acetate of 30 / 70.

[0237] Example A6

[0238] A heat-sensitive recording material was obtained in the same manner as in Example Al except that, in the preparation of the heat-sensitive recording material in Example Al, the following (5) heat-sensitive color-developing printing ink was used instead of (3) heat-sensitive color-developing printing ink.

[0239] Preparation of (5) heat-sensitive color-developing printing ink

[0240] The A liquid 10 parts, the B liquid 20 parts, a 20% aqueous dispersion liquid of colloidal silica having an average particle diameter of 12 nm 8 parts, water 1.9 parts, and isopropyl alcohol 1.9 parts were mixed and stirred, thereby obtaining a heat-sensitive color-developing printing ink.

[0241] Example A7

[0242] A heat-sensitive recording material was obtained in the same manner as in Example Al except that, in the preparation of the B liquid in Example Al, 30 parts of 3-[(phenylcarbamoyl)amino]phenyl-4-methylbenzenesulfonate was used instead of 30 parts of N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea.

[0243] Example A8

[0244] A heat-sensitive recording material was obtained in the same manner as in Example Al except that, in the preparation of the B liquid in Example Al, 30 parts of 5-(N-3-methylphenyl-sulfamoyl)-N',N''-bis-(3-methylphenyl)-isophthalic acid diamide was used instead of 30 parts of N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea.

[0245] Example A9

[0246] In addition to the preparation of the thermal recorder in Example A1, after applying and drying the thermal color printing ink, the thermal recording layer is further printed with the following (6) protective layer ink to form a protective layer, such that the coating weight after drying is 1.0 g / m². 2 In addition, the thermal recorder is obtained in the same manner as in Example A1.

[0247] (6) Preparation of protective ink layer

[0248] 100 parts of acetal resin, 3 parts of zinc stearate, 5 parts of kaolin, 450 parts of isopropanol and 450 parts of methylcyclohexane are mixed and stirred to obtain a protective ink layer.

[0249] Example A10

[0250] Except that in the preparation of the thermal recorder in Example A1, a 23 μm thick celluloid was used instead of a 12 μm thick transparent PET, and a 20 μm thick polyethylene film was laminated on the surface opposite to the surface on which thermal color printing ink was printed, the thermal recorder was obtained in the same manner as in Example A1.

[0251] Example A11

[0252] In addition to the printing process in Example A10, where a 25% toluene solution of chlorinated polypropylene resin (product name: S1306 PPHP adhesive varnish, manufactured by Toyo Ink Co., Ltd.) was used to achieve a dryness of 0.5 g / m², this process was also performed in the preparation of the thermal recorder. 2 The amount of coating is adjusted, and the solution is dried to form a base layer. Then, thermal color printing ink is used to print on the base layer to form a thermal recording layer, in the same manner as in Example A10, to obtain a thermal recorder.

[0253] Comparative Example A1

[0254] Except that in the preparation of solution B in Example A1, 30 parts of 4-hydroxy-4'-isopropoxydiphenyl sulfone were used instead of 30 parts of N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea, the thermal recorder was obtained in the same manner as in Example A1.

[0255] Comparative Example A2

[0256] Except that in the preparation of solution B in Example A1, 30 parts of N-[2-(3-phenylureo)phenyl]benzenesulfonamide were used instead of 30 parts of N,N'-bis-[3-(p-toluenesulfonyloxy)phenyl]urea, the thermal recorder was obtained in the same manner as in Example A1.

[0257] Comparative Example A3

[0258] A thermal sensitive recording body was obtained in the same manner as in Example Al except that, in the preparation of the A liquid and the B liquid in Example Al, polyvinylpyrrolidone resin was used instead of vinylpyrrolidone-vinyl acetate copolymer.

[0259] Comparative Example A4

[0260] A thermal sensitive recording body was obtained in the same manner as in Example Al except that, in the preparation of the A liquid and the B liquid in Example Al, polyvinyl alcohol having a saponification degree of 80 mol% and a polymerization degree of 250 was used instead of vinylpyrrolidone-vinyl acetate copolymer.

[0261] The above examples and comparative examples were evaluated according to the following method. Table 1 shows the results.

[0262] Recording density

[0263] Thermosensitive printer printing

[0264] Recording was performed on each thermal sensitive recording body using a thermal recording tester (product name: TH-PMD, manufactured by Ohkura Electric Co., Ltd.) at an applied energy of 0.24 mJ / dot. The printed portion was placed on PPC paper (JIS P 8148) having a whiteness of 85%, and measurement was performed using a spectrodensitometer (X-Rite 504, manufactured by X-Rite).

[0265] Evaluation

[0266] 1.40 or more: excellent

[0267] 1.25 or more and less than 1.40: good

[0268] 1.10 or more and less than 1.25: practically acceptable

[0269] Less than 1.10: not acceptable

[0270] Laser printing

[0271] Each thermal sensitive recording body was irradiated with laser light using a UV laser marker (product name: UV laser marker, MD-U1000C, manufactured by Keyence Corporation) at a wavelength of 355 nm, an output of 1.2 W, a scanning speed of 3,000 mm / sec, and a laser spot diameter of 14 μm to perform solid printing of 10 mm square. The obtained printed portion was placed on PPC paper (JIS P 8148) having a whiteness of 85%, and measurement was performed using a spectrodensitometer (X-Rite 504, manufactured by X-Rite).

[0272] Evaluation

[0273] 1.40 or more: excellent

[0274] 1.25 or more and less than 1.40: good

[0275] 1.10 or more and less than 1.25: practically acceptable

[0276] less than 1.10: unusable

[0277] Background fogging

[0278] Each of the thermal recording bodies was placed on a PPC paper (JIS P 8148) having a whiteness of 85%, and the background fogging in the non-printed portion was measured with a spectrodensitometer (X-Rite 504, manufactured by X-Rite).

[0279] Evaluation

[0280] less than 0.10: good

[0281] 0.10 or more and less than 0.20: practically acceptable

[0282] 0.20 or more: unusable

[0283] Transparency evaluation

[0284] The transparency of the non-printed portion of each of the thermal recording bodies was measured with a haze meter (NDH-7000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0285] Evaluation

[0286] A: less than 20%

[0287] B: 20% or more and less than 30%

[0288] C: 30% or more and less than 40%

[0289] D: 40% or more

[0290] Plasticizer resistance

[0291] A polycarbonate tube (diameter: 40 mm) was wrapped with three layers of plastic wrap (product name: Hi-S Soft, manufactured by Nippon Carbide Industries Co., Inc.). A sample of each thermosensitive recording body, which was developed with a label printer (product name: L-2000, manufactured by Ishida Co., Ltd.), was placed on top of the wrapped polycarbonate tube, and further wrapped with three layers of plastic wrap. The sample was then left to stand at 40°C for 24 hours. Before and after this treatment, the recording portion was placed on PPC paper (JIS P 8148) having a whiteness of 85%, and the reflection density was measured with a spectrodensitometer (X-Rite 504, manufactured by X-Rite). In addition, the residual rate of the recording portion was calculated using the following formula.

[0292] Residual rate (%) = (recorded density after treatment / recorded density before treatment) x 100

[0293] Evaluation

[0294] 90% or more: excellent

[0295] 70% or more and less than 90%: good

[0296] 50% or more and less than 70%: practically acceptable

[0297] less than 50%: not usable

[0298] Table 1

[0299]

[0300] B. Thermosensitive recording body (B)

[0301] Example B1

[0302] (1) Preparation of dye dispersion liquid (A liquid)

[0303] A mixture of 3-di(n-butyl)amino-6-methyl-7-anilinofluoran 30 parts, a 50% isopropanol solution of a vinylpyrrolidone-vinyl acetate copolymer having a molar ratio of vinylpyrrolidone / vinyl acetate of 30 / 70 13 parts, water 44.5 parts, and isopropanol 12.5 parts was ground using a sand grinder (manufactured by Aimex Co., Ltd.) until an average particle diameter of 0.15 μm was achieved, thereby obtaining a dye dispersion liquid (A liquid).

[0304] (2) Preparation of color developer dispersion liquid (B liquid)

[0305] N,N'-di-[3-(p-toluenesulfonyloxy)phenyl]urea 30 parts, a 50% isopropyl alcohol solution of a vinylpyrrolidone-vinyl acetate copolymer having a molar ratio of vinylpyrrolidone / vinyl acetate of 30 / 70 13 parts, water 44.5 parts, and isopropyl alcohol 12.5 parts were mixed, and ground using a sand grinder (manufactured by Aimex Co., Ltd.) until an average particle diameter of 0.15 μm was achieved, thereby obtaining a color developer dispersion liquid (B liquid).

[0306] (3) Preparation of a thermosensitive color developing printing ink

[0307] A liquid 10 parts, B liquid 20 parts, a 20% water dispersion liquid of colloidal silica having a particle diameter of 12 nm 8 parts, water 1.9 parts, and isopropyl alcohol 1.9 parts were mixed and stirred, thereby obtaining a thermosensitive color developing printing ink.

[0308] (4) Preparation of a protective layer printing ink

[0309] A polyvinyl acetal resin (product name: S-LEC KS-1, number average molecular weight: 27,000, manufactured by Sekisui Chemical Co., Ltd.) 90 parts, an alkyl phosphate ester compound (product name: Phosphanol RD720, Na neutralized salt type, manufactured by Toho Chemical Industry Co., Ltd.) 10 parts, isopropyl alcohol 450 parts, and methylcyclohexane 450 parts were mixed and stirred, thereby obtaining a protective layer printing ink.

[0310] (5) Preparation of a thermosensitive recording body

[0311] A five-color gravure printing machine was used to print on one surface of a transparent PET film having a thickness of 12 μm with the thermosensitive color developing printing ink so that the coated amount after drying was 3.5 g / m 2 , thereby forming a thermosensitive recording layer. In addition, the protective layer printing ink was printed on the thermosensitive recording layer so that the coated amount after drying was 1.0 g / m 2 , and the film was then wound, thereby forming a protective layer. In addition, an ester-based adhesive was applied in an amount of 3 g / m 2 on a surface opposite to the surface on which printing was performed with the thermosensitive color developing printing ink by a dry lamination method, and a low-density polyethylene film having a thickness of 30 μm was adhered to obtain a thermosensitive recording body having a heat-seal layer. The obtained thermosensitive recording body was wound into a small roll using a slitting machine, and further cut into a predetermined shape to prepare a lid material for top sealing, which was then subjected to a sealing process and used for sealing a food packaging container.

[0312] Example B2

[0313] A heat-sensitive recording body was obtained in the same manner as in Example B1 except that, in the preparation of the protective layer ink in Example B1, a polyvinyl acetal resin (trade name: S-LEC KS-10, number average molecular weight: 17,000, manufactured by Sekisui Chemical Co., Ltd.) was used instead of a polyvinyl acetal resin (trade name: S-LEC KS-1, number average molecular weight: 27,000, manufactured by Sekisui Chemical Industries Co., Ltd.).

[0314] Example B3

[0315] A heat-sensitive recording body was obtained in the same manner as in Example B1 except that, in the preparation of the protective layer ink in Example B1, a polyvinyl acetal resin (trade name: S-LEC KS-10, number average molecular weight: 17,000, manufactured by Sekisui Chemical Co., Ltd.) was used instead of a polyvinyl acetal resin (trade name: S-LEC KS-1, number average molecular weight: 27,000, manufactured by Sekisui Chemical Industries Co., Ltd.).

[0316] Example B4

[0317] A heat-sensitive recording body was obtained in the same manner as in Example B1 except that, in the preparation of the protective layer ink in Example B1, an alkyl phosphate ester compound (trade name: Phosphanol SC6103L, Ca neutral salt type, manufactured by Toho Chemical Industry Co., Ltd.) was used instead of an alkyl phosphate ester compound (trade name: Phosphanol RD720, Na neutral salt type, manufactured by Toho Chemical Industry Co., Ltd.).

[0318] Example B5

[0319] A heat-sensitive recording body was obtained in the same manner as in Example B1 except that, in the preparation of the protective layer ink in Example B1, an alkyl phosphate ester compound (trade name: Phosphanol RL-210, first acid value: 90 mgKOH / g to 100 mgKOH / g, manufactured by Toho Chemical Industry Co., Ltd.) was used instead of an alkyl phosphate ester compound (trade name: Phosphanol RD720, Na neutral salt type, manufactured by Toho Chemical Industry Co., Ltd.).

[0320] Example B6

[0321] A heat-sensitive recording body was obtained in the same manner as in Example Bl except that the following (6) protective layer printing ink was used instead of the (4) protective layer printing ink of Example Bl.

[0322] Preparation of (6) protective layer printing ink

[0323] A protective layer printing ink was obtained by mixing and stirring 90 parts of a polyvinyl acetal resin (product name: S-LEC KS-1, number average molecular weight: 27,000, manufactured by Sekisui Chemical Co., Ltd.), 10 parts of an alkyl phosphate ester compound (product name: Phosphanol RD720, Na neutral salt type, manufactured by Toho Chemical Industry Co., Ltd.), 5 parts of a 20% isopropyl alcohol dispersion liquid of calcined kaolin having an average particle diameter of 1.2 μm, 450 parts of isopropyl alcohol, and 450 parts of methylcyclohexane.

[0324] Example B7

[0325] A heat-sensitive recording body was obtained in the same manner as in Example Bl except that, in the preparation of the heat-sensitive recording body in Example Bl, 23 μm-thick cellophane was used instead of 12 μm-thick transparent PET, and a 20 μm-thick polyethylene film was adhered to the surface opposite to the surface on which the heat-sensitive color developing printing ink was printed by an extrusion lamination method.

[0326] Reference Example Bl

[0327] A heat-sensitive recording body was obtained in the same manner as in Example Bl except that, in the preparation of the protective layer printing ink in Example Bl, 100 parts of an acrylic resin (trade name: BR101, number average molecular weight: 160,000, manufactured by Mitsubishi Chemical Corporation) was used instead of 90 parts of a polyvinyl acetal resin (trade name: S-LEC KS-1, number average molecular weight: 27,000, manufactured by Sekisui Chemical Co., Ltd.).

[0328] Reference Example B2

[0329] A heat-sensitive recording body was obtained in the same manner as in Example Bl except that, in the preparation of the protective layer printing ink in Example Bl, 100 parts of an acrylic resin (trade name: BR115, number average molecular weight: 50,000, manufactured by Mitsubishi Chemical Corporation) was used instead of 90 parts of a polyvinyl acetal resin (trade name: S-LEC KS-1, number average molecular weight: 27,000, manufactured by Sekisui Chemical Co., Ltd.).

[0330] Reference Example B3

[0331] A heat-sensitive recording body was obtained in the same manner as in Example B1 except that, in the preparation of the protective layer printing ink in Example B1, 100 parts of a styrene-acrylic resin (trade name: UC-3080, number average molecular weight: 14,000, manufactured by Toagosei Co., Ltd.) was used instead of 90 parts of a polyvinyl acetal resin (trade name: S-LEC KS-1, number average molecular weight: 27,000, manufactured by Sekisui Chemical Co., Ltd.).

[0332] Reference Example B4

[0333] A heat-sensitive recording body was obtained in the same manner as in Example B1 except that, in the preparation of the protective layer printing ink in Example B1, 10 parts of zinc stearate (average particle diameter: 1.2 μm) was used instead of 10 parts of an alkyl phosphate compound (trade name: Phosphanol RD720, Na neutralized salt type, manufactured by Toho Chemical Industry Co., Ltd.).

[0334] The above examples and reference examples were evaluated according to the following methods. Table 2 shows the results.

[0335] Transparency evaluation

[0336] The transparency of the non-printed portion of each heat-sensitive recording body was measured using a haze meter (NDH-7000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0337] Evaluation

[0338] A: Less than 20%: Good

[0339] B: 20% or more and less than 30%: Acceptable for practical use

[0340] C: 30% or more: Not usable

[0341] Background heat resistance

[0342] Each heat-sensitive recording body was placed on PPC paper (JIS P 8148) having a whiteness of 85%, and the background fogging in the non-printed portion was measured with a spectrodensitometer (X-Rite 504, manufactured by X-Rite).

[0343] Evaluation

[0344] Less than 0.15: Good

[0345] 0.15 or more and less than 0.25: practically acceptable for use

[0346] 0.25 or more: not usable

[0347] Plasticizer resistance

[0348] A polycarbonate tube (diameter: 40 mm) was wrapped with a three-layer plastic wrap (product name: Hi-S Soft, manufactured by Nippon Carbide Industries Co., Inc.). A sample of each thermal recording body, which was visualized with a label printer (product name: L-2000, manufactured by Ishida Co., Ltd.), was placed on top of the wrapped polycarbonate tube, and further wrapped with a three-layer plastic wrap. Then, the sample was left to stand at 40°C for 24 hours. Before and after this treatment, the recording portion was placed on PPC paper (JIS P 8148) having a whiteness of 85%, and the reflection density was measured with a spectrodensitometer (X-Rite 504, manufactured by X-Rite). In addition, the residual rate of the recording portion was calculated using the following formula.

[0349] Residual rate (%) = (recording density after treatment / recording density before treatment) x 100

[0350] Printing sound

[0351] Using a thermal recording tester (product name: TH-PMD, manufactured by Ohkura Electric Co., Ltd.), recording was performed on each thermal recording body at an applied energy of 0.243 mJ / dot, during which the printing sound was measured by sensory evaluation.

[0352] Evaluation

[0353] A: quiet printing sound

[0354] B: weak printing noise (practically acceptable for use)

[0355] C: large printing sound

[0356] Head residue applicability

[0357] Using a label printer (L'esprit V-ex, manufactured by Sato Corporation), printing was performed at 50 cm at 100% black solid coverage, and using a stereomicroscope (VH-Z100UR, manufactured by Keyence Corporation), the heating elements of the thermal head were observed and sensory evaluation was performed.

[0358] Evaluation

[0359] A: No adhesion of head residue

[0360] B: Slight presence of head residue

[0361] C: Light adhesion of head residue (acceptable for practical use)

[0362] D: Significant amount of head residue

[0363] Table 2

[0364]

Claims

1. A printing ink for thermal recording media, comprising either (A) or (B): (A) A thermal color-developing printing ink, comprising a leuco dye, a color developer, a vinylpyrrolidone-vinyl acetate copolymer, and a solvent. The thermal color-developing printing ink contains at least one selected from the group consisting of: N,N'-diarylurea compounds represented by the following formula (1): in R 0 Indicate C 1-12 Alkyl, C 7-12 Aryl or C 6-12 Aryl, wherein the aralkyl group and the aryl group can be C 1-12 Alkyl, C 1-12 Alkoxy, C 6-12 Aryl or halogen atoms are substituted, and multiple R atoms are present. 0 They can be the same or different, and A 1 Represents a hydrogen atom or C 1-4 Alkyl groups, and multiple A groups 1 They can be the same or different; Compounds represented by the following formula (2): in R 1 To R 5 Same or different, and representing hydrogen atom, halogen atom, nitro, amino, alkyl, alkoxy, aryloxy, alkylcarbonyloxy, arylcarbonyloxy, alkylcarbonylamino, arylcarbonylamino, alkylsulfonylamino, arylsulfonylamino, monoalkylamino, dialkylamino, or arylamino; and 5-(N-3-methylphenyl-aminosulfonyl)-N',N''-bis-(3-methylphenyl)-isophthalic acid diamide, and (B) A protective layer printing ink for thermal recorders, comprising a binder, a lubrication agent, and a solvent, wherein the protective layer printing ink comprises a polyvinyl acetal resin as the binder and an alkyl phosphate ester and / or its salt as the lubrication agent.

2. The printing ink according to claim 1, wherein the printing ink is the (A) thermosensitive color-developing printing ink.

3. The printing ink according to claim 2, wherein, based on the total solids content of the thermochromic printing ink, the content of the leuco dye is 15% to 40% by mass, the content of the developer is 20% to 70% by mass, and the content of the vinylpyrrolidone-vinyl acetate copolymer is 5% to 35% by mass.

4. The printing ink according to claim 2 or 3, wherein the molar ratio of vinylpyrrolidone to vinyl acetate in the vinylpyrrolidone-vinyl acetate copolymer is from 50 / 50 to 30 / 70.

5. The printing ink according to claim 2 or 3, further comprising colloidal silica with an average particle size of less than 45 nm, wherein the content of the colloidal silica is from 5% to 30% by mass based on the total solids content of the thermosensitive color-developing printing ink.

6. The printing ink according to claim 2 or 3, comprising water and alcohol as the solvent.

7. The printing ink according to claim 1, wherein the printing ink is the protective layer printing ink for the (B) thermal recorder.

8. The printing ink according to claim 7, wherein, based on the total solids content of the protective layer printing ink, the content of the polyvinyl acetal resin is from 75% to 99% by mass, and the content of the alkyl phosphate ester and / or its salt is from 1% to 25% by mass.

9. The printing ink according to claim 7 or 8, wherein the number average molecular weight of the polyvinyl acetal resin is from 17,000 to 40,000.

10. The printing ink according to claim 7 or 8, wherein the alkyl phosphate salt is in its Na-neutralized or Ca-neutralized form, and the first acid value of the alkyl phosphate is less than 135 mg KOH / g.

11. The printing ink according to claim 7 or 8, further comprising calcined kaolin with an average particle size of less than 2.0 μm, wherein the content of the calcined kaolin is from 0.5% by mass to 10% by mass based on the total solids content of the protective layer printing ink.

12. The printing ink according to claim 7 or 8, comprising an alcohol and a cycloalkanes as the solvent.

13. The printing ink according to any one of claims 1 to 3, 7 and 8, wherein the printing ink is an ink for gravure printing.

14. A thermal recording medium comprising: Support body, and A thermal recording layer formed of the printing ink according to claim 2 or 3 and / or a protective layer formed of the printing ink according to claim 7 or 8 on at least a portion of one or both surfaces of the support.

15. The thermal recorder according to claim 14, wherein the support is a translucent or transparent support made of cellophane or laminated resin paper, or a transparent film made of celluloid or synthetic resin film.

16. The thermal recording device of claim 14, comprising a printed layer on at least a portion of the surface of the support opposite to the surface on which the thermal recording layer exists.

17. The thermal recorder of claim 14, comprising a heat-sealing layer on at least a portion of one or both surfaces of the support.

18. The thermal recording device of claim 14, comprising an undercoating layer between the support and the thermal recording layer.

19. The thermal recorder of claim 18, wherein the undercoat comprises a chlorinated polyolefin resin as a binder.

20. The thermal recorder according to claim 17, used as a top sealing cap material.

21. An image recording method comprising recording an image on a thermal recorder as claimed in claim 14 by using a laser or a thermal head.

Images