Thermosensitive recording layer forming liquid, thermosensitive recording medium, method for producing the same, and image recording method

Abstract

A heat-sensitive recording medium is provided, which includes a support and a heat-sensitive recording layer provided on or over the support. The heat-sensitive recording layer includes a compound represented by general formula (1) and a styrene-acrylic acid resin, wherein, in general formula (1), R2 is a C1-12 straight chain, branched chain or alicyclic alkyl group, a C7-12 aralkyl group substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group or a halogen atom, or a C6-12 aryl group which is unsubstituted or substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group or a halogen atom, wherein two or more R2 can be the same as or different from each other; and A1 is a hydrogen atom or a C1-4 alkyl group, wherein two or more A1 can be the same as or different from each other.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a heat-sensitive recording layer forming liquid, a heat-sensitive recording medium, a production method thereof, and an image recording method. BACKGROUND

[0002] Compared with other recording methods, the heat-sensitive recording method using a heat-sensitive recording medium has the advantage that recording can be performed in a short time using a relatively simple apparatus without performing processes such as developing and fixing, and it is low in cost. Therefore, the heat-sensitive recording method has been rapidly spread in the field of foods such as packaged foods and instant foods in which image reliability is important.

[0003] In the field of foods, a heat-sensitive recording medium has been used as a label for a PET bottle or a label for fresh foods. Therefore, it is expected that the heat-sensitive recording medium will be exposed to water or hot water during use. When the image area of the heat-sensitive recording medium is in contact with water or hot water, the image area in contact with the water or hot water can be discolored or faded. In particular, at a hot beverage temperature sold at a bending machine (for example, the temperature is maintained at 60°C for several hours), a hot water temperature tapped from a faucet (for example, the temperature is maintained at 60°C for several minutes), or a temperature of a hot wash mode of a washing machine (for example, the temperature is maintained at 40°C to 60°C for several hours), discoloration or fading is expected to occur.

[0004] In addition, packaging films for various containers such as a PET bottle for soft drinks, a can for coffee and the like, a bottle for energy drinks or medical products, and a beer bottle and the like, and packaging labels for the field of POS systems for fresh foods, bento, prepared meals, and the like, are expected to have all of ethanol resistance, temperature resistance and moisture resistance, wet rub resistance and heat resistance, and the above-mentioned hot water resistance and water resistance.

[0005] Therefore, in order to improve the water resistance of the image area, it has been suggested, for example, to add polyvinyl alcohol and a polyamide epichlorohydrin resin to the heat-sensitive recording layer; to use a hydrophobic resin emulsion such as a vinyl acetate emulsion, an acrylic emulsion, and an SBR latex as a binder for the heat-sensitive recording layer; or to use a non-phenolic color developer not including a phenolic compound as a color developer for the heat-sensitive recording layer (for example, see PTL 1).

[0006] LIST OF CITATIONS

[0007] PATENT LITERATURE

[0008] PTL 1: Japanese Patent No. 6,751,479 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] The present disclosure aims to provide a heat-sensitive recording medium that is capable of forming a high concentration image and has hot water resistance, water resistance, ethanol resistance, temperature and humidity resistance, humidity and heat resistance, and heat resistance.

[0011] Technical Solution

[0012] According to one aspect of the present disclosure, a heat-sensitive recording medium includes a support and a heat-sensitive recording layer disposed on or over the support. The heat-sensitive recording layer includes a compound represented by general formula (1) and a styrene-acrylic resin.

[0013] [Chemical Formula 1]

[0014]

[0015] In general formula (1), R2 is a C1-12 linear, branched, or alicyclic alkyl group, a C1-12 alkoxy group that is unsubstituted or substituted with a C1-12 alkyl group, a C7-12 aralkyl group that is substituted with a C6-12 aryl group or a halogen atom, or a C6-12 aryl group that is unsubstituted or substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom, wherein two or more R2 can be the same as or different from each other; and A1 is a hydrogen atom or a C1-4 alkyl group, wherein two or more A1 can be the same as or different from each other.

[0016] Advantages of the Invention

[0017] The present disclosure can provide a heat-sensitive recording medium that is capable of forming a high concentration image while having hot water resistance, water resistance, ethanol resistance, temperature and humidity resistance, humidity and heat resistance, and heat resistance. BRIEF DESCRIPTION OF DRAWINGS

[0018] [ Figure 1 ] Figure 1 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to a first embodiment.

[0019] [ Figure 2 ] Figure 2 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to a second embodiment.

[0020] [ Figure 3 ] Figure 3 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to a third embodiment.

[0021] [ Figure 4 ] Figure 4 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to a fourth embodiment.

[0022] [ Figure 5 ]Figure 5 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to the fifth embodiment.

[0023] [ Figure 6 ] Figure 6 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to the sixth embodiment.

[0024] [ Figure 7 ] Figure 7 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to the seventh embodiment.

[0025] [ Figure 8 ] Figure 8 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to the eighth embodiment.

[0026] [ Figure 9 ] Figure 9 is a schematic view illustrating an example of an image recording apparatus for the image recording method of the present disclosure.

[0027] [ Figure 10 ] Figure 10 is a schematic view illustrating another example of an image recording apparatus for the image recording method of the present disclosure.

[0028] [ Figure 11 ] Figure 11 is a view illustrating an arrangement state of a laser array of an image recording apparatus for the image recording method of the present disclosure. DETAILED DESCRIPTION

[0029] (Heat-sensitive recording medium)

[0030] The heat-sensitive recording medium of the present disclosure is a heat-sensitive recording medium including a support and a heat-sensitive recording layer provided on or over the support. The heat-sensitive recording layer includes a compound represented by general formula (1) and a styrene-acrylic acid resin. As needed, the heat-sensitive recording medium can further include other layers.

[0031] [Chemical Formula 2]

[0032]

[0033] In General Formula (1), R2is a C1-12 linear, branched, or alicyclic alkyl group, a C1-12 alkoxy group which is unsubstituted or substituted with a C1-12 alkyl group, a C7-12 aralkyl group which is substituted with a C6-12 aryl group or a halogen atom, or a C6-12 aryl group which is unsubstituted or substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom, and two or more R2may be the same as or different from each other; and A1is a hydrogen atom or a C1-4 alkyl group, and two or more A1may be the same as or different from each other.

[0034] In the related art, by using a certain non-phenolic color developer, it is possible to ensure water resistance of the heat-sensitive recording medium against water at ordinary temperature (25°C), but there is a problem that the image area of the heat-sensitive recording medium is discolored or faded when the heat-sensitive recording medium is exposed to hot water (60°C or higher).

[0035] In the present disclosure, the heat-sensitive recording medium includes a support and a heat-sensitive recording layer on or over the support, and the heat-sensitive recording layer includes a compound represented by General Formula (1) and a styrene-acrylic acid resin. Thus, the heat-sensitive recording medium of the present disclosure can form a high-density image, and achieve all of hot water resistance, water resistance, ethanol resistance, temperature resistance, and humidity resistance, humidity and heat resistance, and heat resistance.

[0036] <Heat-sensitive recording layer>

[0037] The heat-sensitive recording layer includes a compound represented by General Formula (1) and a styrene-acrylic acid resin, and preferably further includes a leuco dye and a light-heat conversion material. The heat-sensitive recording layer can further include other components.

[0038] <<Compound represented by General Formula (1)>>

[0039] The compound represented by General Formula (1) is a non-phenolic color developer. The term "non-phenolic" means that the compound does not have a phenol skeleton. Since the heat-sensitive recording layer includes a non-phenolic color developer, the heat-sensitive recording layer does not need to include a phenolic color developer which can be determined as an endocrine disruptor, and thus the resulting heat-sensitive recording medium is excellent in view of the influence on the environment.

[0040] In General Formulae (1) and (2), R2is a C1-12 linear, branched, or alicyclic alkyl group, or a C7-12 aralkyl group or a C6-12 aryl group which is unsubstituted or substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom, and two or more R2may be the same as or different from each other; and A1is a hydrogen atom or a C1-4 alkyl group, and two or more A1may be the same as or different from each other.

[0041] In General Formula (3), R is an alkyl group, and n is an integer of 0 to 3. The number of carbon atoms of the alkyl group of R can be 1 to 12, 1 to 8, or 1 to 4.

[0042] In General Formula (1), the substitution position of the plurality of R2-SO3- can be the same as or different from each other. The substitution position thereof is preferably the 3-position, the 4-position, or the 5-position, more preferably the 3-position.

[0043] Examples of the C1-12 linear, branched, or alicyclic alkyl group of R2include C1-12 linear, branched, or alicyclic alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, cyclopentyl, hexyl, cyclohexyl, 2-ethylhexyl, and lauroyl.

[0044] Examples of the aralkyl group include aralkyl groups which are unsubstituted or substituted with an alkyl group, an alkoxy group, an aralkyl group, an aryl group, or a halogen atom, such as benzyl, 1-phenylethyl, 2-phenylethyl, 3-phenylpropyl, p-methylbenzyl, m-methylbenzyl, o-methylbenzyl, p-ethylbenzyl, p-isopropylbenzyl, p-t-butylbenzyl, p-methoxybenzyl, m-methoxybenzyl, o-methoxybenzyl, m,p-dimethoxybenzyl, p-ethoxy-m-methoxybenzyl, p-phenylmethylbenzyl, p-cumylbenzyl, p-phenylbenzyl, o-phenylbenzyl, m-phenylbenzyl, p-tolylbenzyl, m-tolylbenzyl, o-tolylbenzyl, or p-chlorobenzyl.

[0045] Examples of the aryl group include aryl groups which are unsubstituted or substituted with an alkyl group, an alkoxy group, an aralkyl group, an aryl group, or a halogen atom, such as phenyl, p-tolyl, m-tolyl, o-tolyl, 2,5-dimethylphenyl, 2,4-dimethylphenyl, 3,5-dimethylphenyl, 2,3-dimethylphenyl, 3,4-dimethylphenyl, a mesitylene group, p-ethylphenyl, p-isopropylphenyl, p-t-butylphenyl, p-methoxyphenyl, 3,4-dimethoxyphenyl, p-ethoxyphenyl, p-chlorophenyl, 1-naphthyl, 2-naphthyl, and t-butylated naphthyl.

[0046] The substitution position of the plurality of A1may be the same substitution site, or different substitution sites. The substitution position thereof is preferably the 3-position, the 4-position, or the 5-position.

[0047] A1is a hydrogen atom or an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group.

[0048] Specific examples of the compounds represented by General Formulas (1) to (3) include, but are not limited to, the following compounds. Two or more compounds can be used in combination as a color developer.

[0049] Further, the use of a combination of known color developers, such as a combination of known non-phenolic color developers (e.g., N-3-[(p-tolylsulfonyl)oxy]phenyl-N'-(p-tolylsulfonyl)-urea and N-[2-(3-phenylureido)phenyl]- benzenesulfonamide) and known color developers (e.g., 4,4'-isopropylidene diphenol (BPA), 4,4'-dihydroxydiphenyl sulfone (BPS), 4-allyloxy-4'-hydroxydiphenyl sulfone, 4-allyloxy-4'-hydroxy-diphenyl sulfone, 4-hydroxy-4'-isopropoxy sulfone, N-(m-tolylaminocarbonyl)-methionine, N-(m-tolylaminocarbonyl)-phenylalanine, and N-(phenylaminocarbonyl)-phenylalanine) can further improve the preservation problems that exist with known color developers.

[0050] Examples of the compounds represented by general formulas (1) to (3) include N,N'-di-[3-(phenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(phenylsulfonyloxy)-4-methyl-phenyl]urea, N,N'-di-[3-(phenylsulfonyloxy)-4-ethyl-phenyl]urea, N,N'-di-[3-(phenylsulfonyloxy)-5-methyl-phenyl]urea, N,N'-di-[3-(phenylsulfonyloxy)-4-propyl-phenyl]urea,

[0051] N,N'-di-[3-(p-tolylsulfonyloxy)phenyl]urea, N,N'-di-[3-(m-tolylsulfonyloxy)phenyl]urea, N,N'-di-[3-(o-tolylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-xylylsulfonyloxy)-4-methyl-phenyl]urea, N,N'-di-[3-(mesitylsulfonyloxy)phenyl]urea, N,N'-di-[3-(1-naphthylsulfonyloxy)phenyl]urea, N,N'-di-[3-(2-naphthylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-ethylphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-propylphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-isopropylphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-tert-butylphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-methoxyphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(m-methoxyphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(o-methoxyphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(m,p-dimethoxyphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-ethoxyphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-propoxyphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-butoxyphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-cumylbenzylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-cumylphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(o-phenylphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-phenylphenylsulfonyloxy)phenyl]urea, N,N'-di-[3-(p-chlorophenylsulfonyloxy)phenyl]urea,

[0052] N-[3-(phenylsulfonyloxy)phenyl]-N'-[3-(p-tolylsulfonyloxy)phenyl]urea, N-[3-(phenylsulfonyloxy)phenyl]-N'-[3-(m-tolylsulfonyloxy)phenyl]urea, N-[3-(phenylsulfonyloxy)phenyl]-N'-[3-(o-tolylsulfonyloxy)phenyl]urea, N-[3-(phenylsulfonyloxy)phenyl]-N'-[3-(p-xylidylsulfonyloxy)phenyl]urea, N-[3-(phenylsulfonyloxy)phenyl]-N'-[3-(1-naphthalenylsulfonyloxy)phenyl]urea, N-[3-(phenylsulfonyloxy)phenyl]-N'-[3-(2-naphthalenylsulfonyloxy)phenyl]urea, N-[3-(phenylsulfonyloxy)phenyl]-N'-[3-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[3-(phenylsulfonyloxy)phenyl]-N'-[3-(p-methoxyphenylsulfonyloxy)phenyl]urea, N-[3-(phenylsulfonyloxy)phenyl]-N'-[3-(benzylsulfonyloxy)phenyl]urea, N-[3-(phenylsulfonyloxy)phenyl]-N'-[3-(ethanesulfonyloxy)phenyl]urea, N-[3-(phenylsulfonyloxy)phenyl]-N'-[3-(phenylsulfonyloxy)-4-methylphenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(m-tolylsulfonyloxy)phenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(o-tolylsulfonyloxy)phenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(p-tolylsulfonyloxy)-4-methylphenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(p-methoxyphenylsulfonyloxy)phenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(2-naphthalenylsulfonyloxy)phenyl]urea,

[0053] N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(benzylsulfonyloxy)phenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(p-methylbenzylsulfonyloxy)phenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(p-methoxybenzylsulfonyloxy)phenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(methanesulfonyloxy)phenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(propanesulfonyloxy)phenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[3-(butanesulfonyloxy)phenyl]urea,

[0054] N,N'-Bis-[3-(benzylsulfonyloxy)phenyl]urea, N,N'-Bis-[3-(benzylsulfonyloxy)-4-methyl-phenyl]urea, N,N'-Bis-[3-(phenylethane-sulfonyloxy)phenyl]urea, N,N'-Bis-[3-(phenylpropane-sulfonyloxy)phenyl]urea, N,N'-Bis-[3-(p-methoxybenzylsulfonyloxy)phenyl]urea,

[0055] N-[3-(Benzylsulfonyloxy)phenyl]-N'-[3-(p-methoxybenzylsulfonyloxy)phenyl]urea, N-[3-(Benzylsulfonyloxy)phenyl]-N'-[3-(ethanesulfonyloxy)phenyl]urea, N-[3-(Benzylsulfonyloxy)phenyl]-N'-[3-(butanesulfonyloxy)phenyl]urea,

[0056] N,N'-Bis-[3-(methanesulfonyloxy)phenyl]urea, N,N'-Bis-[3-(methanesulfonyloxy)-4-methyl-phenyl]urea, N,N'-Bis-[3-(methanesulfonyloxy)-4-ethyl-phenyl]urea, N,N'-Bis-[3-(methanesulfonyloxy)-5-methyl-phenyl]urea, N,N'-Bis-[3-(methanesulfonyloxy)-4,5-dimethyl-phenyl]urea, N,N'-Bis-[3-(ethanesulfonyloxy)phenyl]urea, N,N'-Bis-[3-(ethanesulfonyloxy)-4-methyl-phenyl]urea, N,N'-Bis-[3-(1-propanesulfonyloxy)phenyl]urea, N,N'-Bis-[3-(2-propanesulfonyloxy)phenyl]urea, N,N'-Bis-[3-(butanesulfonyloxy)phenyl]urea, N,N'-Bis-[3-(pentanesulfonyloxy)phenyl]urea, N,N'-Bis-[3-(hexanesulfonyloxy)phenyl]urea, N,N'-Bis-[3-(cyclohexanesulfonyloxy)phenyl]urea, N,N'-Bis-[3-(dodecanesulfonyloxy)phenyl]urea,

[0057] N-[3-(Methanesulfonyloxy)phenyl]-N'-[3-(ethanesulfonyloxy)phenyl]urea, N-[3-(Ethanesulfonyloxy)phenyl]-N'-[3-(propanesulfonyloxy)phenyl]urea, N-[3-(Methanesulfonyloxy)phenyl]-N'-[3-(butanesulfonyloxy)phenyl]urea, N-[3-(Ethanesulfonyloxy)phenyl]-N'-[3-(cyclohexanesulfonyloxy)phenyl]urea,

[0058] N,N'-Bis-[4-(phenylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(phenylsulfonyloxy)-3-methyl-phenyl]urea, N,N'-Bis-[4-(phenylsulfonyloxy)-3-ethyl-phenyl]urea, N,N'-Bis-[4-(phenylsulfonyloxy)-3-propyl-phenyl]urea, N,N'-Bis-[4-(phenylsulfonyloxy)-3-tert-butyl-phenyl]urea,

[0059] N,N'-Bis-[4-(p-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(m-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(o-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(p-tolylsulfonyloxy)-3-methyl-phenyl]urea,

[0060] N,N'-Bis-[4-(p-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(m-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(o-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(p-tolylsulfonyloxy)-3-methyl-phenyl]urea,

[0061] N,N'-Bis-[4-(p-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(m-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(o-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(p-tolylsulfonyloxy)-3-methyl-phenyl]urea,

[0062] N,N'-Bis-[4-(p-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(m-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(o-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(p-tolylsulfonyloxy)-3-methyl-phenyl]urea,

[0063] N,N'-Bis-[4-(p-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(m-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(o-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(p-tolylsulfonyloxy)-3-methyl-phenyl]urea,

[0064] N,N'-Bis-[4-(p-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(m-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(o-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(p-tolylsulfonyloxy)-3-methyl-phenyl]urea,

[0065] N,N'-Bis-[4-(p-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(m-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(o-tolylsulfonyloxy)phenyl]urea, N,N'-Bis-[4-(p-tolylsulfonyloxy)-3-methyl-phenyl]urea,

[0066] N-[4-(phenylsulfonyloxy)phenyl]-N'-[4-(p-tolylsulfonyloxy)phenyl]urea, N-[4-(phenylsulfonyloxy)phenyl]-N'-[4-(m-tolylsulfonyloxy)phenyl]urea, N-[4-(phenylsulfonyloxy)phenyl]-N'-[4-(o-tolylsulfonyloxy)phenyl]urea, N-[4-(phenylsulfonyloxy)phenyl]-N'-[4-(p-xylidylsulfonyloxy)phenyl]urea, N-[4-(phenylsulfonyloxy)phenyl]-N'-[4-(mesitylenesulfonyloxy)phenyl]urea, N-[4-(phenylsulfonyloxy)phenyl]-N'-[4-(1-naphthalenesulfonyloxy)phenyl]urea, N-[4-(phenylsulfonyloxy)phenyl]-N'-[4-(2-naphthalenesulfonyloxy)phenyl]urea, N-[4-(phenylsulfonyloxy)phenyl]-N'-[4-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[4-(phenylsulfonyloxy)phenyl]-N'-[4-(p-methoxyphenylsulfonyloxy)phenyl]urea, N-[4-(phenylsulfonyloxy)phenyl]-N'-[4-(benzylsulfonyloxy)phenyl]urea, N-[4-(phenylsulfonyloxy)phenyl]-N'-[4-(ethanesulfonyloxy)phenyl]urea, N-[4-(p-tolylsulfonyloxy)phenyl]-N'-[4-(m-tolylsulfonyloxy)phenyl]urea, N-[4-(p-tolylsulfonyloxy)phenyl]-N'-[4-(o-tolylsulfonyloxy)phenyl]urea, N-[4-(p-tolylsulfonyloxy)phenyl]-N'-[4-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[4-(p-tolylsulfonyloxy)phenyl]-N'-[4-(p-methoxyphenylsulfonyloxy)phenyl]urea, N-[4-(p-tolylsulfonyloxy)phenyl]-N'-[4-(2-naphthalenesulfonyloxy)phenyl]urea,

[0067] N-[4-(p-tolylsulfonyloxy)phenyl]-N'-[4-(benzylsulfonyloxy)phenyl]urea, N-[4-(p-tolylsulfonyloxy)phenyl]-N'-[4-(p-methylbenzylsulfonyloxy)phenyl]urea, N-[4-(p-tolylsulfonyloxy)phenyl]-N'-[4-(p-methoxybenzylsulfonyloxy)phenyl]urea, N-[4-(p-tolylsulfonyloxy)phenyl]-N'-[4-(methanesulfonyloxy)phenyl]urea, N-[4-(p-tolylsulfonyloxy)phenyl]-N'-[4-(propanesulfonyloxy)phenyl]urea, N-[4-(p-tolylsulfonyloxy)phenyl]-N'-[4-(butanesulfonyloxy)phenyl]urea,

[0068] N,N'-di-[4-(benzylsulfonyloxy)phenyl]urea, N,N'-di-[4-(benzylsulfonyloxy)-3-methyl-phenyl]urea, N,N'-di-[4-(phenyl ethane sulfonyloxy)phenyl]urea, N,N'-di-[4-(phenylpropane sulfonyloxy)phenyl]urea, N,N'-di-[4-(p-methoxybenzylsulfonyloxy)phenyl]urea,

[0069] N-[4-(benzylsulfonyloxy)phenyl]-N'-[4-(methane- sulfonyloxy)phenyl]urea, N-[4-(benzylsulfonyloxy)phenyl]-N'-[4-(ethane- sulfonyloxy)phenyl]urea,

[0070] N,N'-di-[4-(methane-sulfonyloxy)-3-methyl-phenyl]urea, N,N'-di-[4-(methane- sulfonyloxy)-3-methyl-phenyl]urea, N,N'-di-[4-(methane-sulfonyloxy)-3,5- dimethyl-phenyl]urea, N,N'-di-[4-(ethane-sulfonyloxy)phenyl]urea, N,N'-di-[4- (ethane-sulfonyloxy)-3-methyl-phenyl]urea, N,N'-di-[4-(1-propane- sulfonyloxy)phenyl]urea, N,N'-di-[4-(2-propane-sulfonyloxy)phenyl]urea, N,N'- di-[4-(butane-sulfonyloxy)phenyl]urea, N,N'-di-[4-(pentane-sulfonyloxy)phenyl] urea, N,N'-di-[4-(hexane-sulfonyloxy)phenyl]urea, N,N'-di-[4-(cyclohexane- sulfonyloxy)phenyl]urea, N,N'-di-[4-(dodecane-sulfonyloxy)phenyl]urea,

[0071] N-[4-(benzylsulfonyloxy)phenyl]-N'-[4-(methane- sulfonyloxy)phenyl]urea, N-[4-(benzylsulfonyloxy)phenyl]-N'-[4-(ethane- sulfonyloxy)phenyl]urea,

[0072] N,N'-di-[2-(phenylsulfonyloxy)-4-ethyl-phenyl]urea, N,N'-di-[2-(phenylsulfonyloxy)-5-methyl-phenyl]urea, N,N'-di-[2-(phenylsulfonyloxy)-4- propyl-phenyl]urea,

[0073] N,N'-di-[2-(p-tolylsulfonyloxy)-4-methyl-phenyl]urea, N,N'-di-[2-(p-tolylsulfonyloxy)phenyl]urea, N,N'-di-[2-(p-tolylsulfonyloxy)-4- methyl-phenyl]urea,

[0074] N,N'-di-[2-(p-tolylsulfonyloxy)-4-methyl-phenyl]urea, N,N'-di-[2-(p-tolylsulfonyloxy)phenyl]urea, N,N'-di-[2-(p-tolylsulfonyloxy)-4- methyl-phenyl]urea,

[0075] N,N'-bis-[2-(2-naphthalenesulfonyloxy)phenyl]urea,

[0076] N,N'-bis-[2-(p-tert-butylbenzenesulfonyloxy)phenyl]urea,

[0077] N,N'-bis-[2-(p-tert-butylbenzenesulfonyloxy)phenyl]urea,

[0078] N,N'-bis-[2-(p-tert-butylbenzenesulfonyloxy)phenyl]urea,

[0079] N,N'-bis-[2-(p-tert-butylbenzenesulfonyloxy)phenyl]urea,

[0080] N-[2-(phenylsulfonyloxy)phenyl]-N'-[2-(p-tolylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[2-(m-tolylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[2-(o-tolylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[2-(p-xylidylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[2-(mesitylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[2-(1-naphthalenesulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[2-(2-naphthalenesulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[2-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[2-(p-methoxyphenylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[2-(benzylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[2-(ethanesulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[2-(m-tolylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[2-(o-tolylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[2-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[2-(p-methoxyphenylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[2-(2-naphthalenesulfonyloxy)phenyl]urea,

[0081] N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[2-(benzylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[2-(p-methylbenzylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[2-(p-methoxybenzylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[2-(methanesulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[2-(propanesulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[2-(butanesulfonyloxy)phenyl]urea,

[0082] N,N'-di-[2-(benzylsulfonyloxy)phenyl]urea, N,N'-di-[2-(benzylsulfonyloxy)-4-methyl-phenyl]urea, N,N'-di-[2-(phenylethanolsulfonyloxy)phenyl]urea, N,N'-di-[2-(phenylpropanolsulfonyloxy)phenyl]urea, N,N'-di-[2-(p-methoxybenzylsulfonyloxy)phenyl]urea,

[0083] N-[2-(benzylsulfonyloxy)phenyl]-N'-[2-(propane- sulfonyloxy)phenyl]urea, N-[2-(benzylsulfonyloxy)phenyl]-N'-[2-(p- methoxybenzylsulfonyloxy)phenyl]urea,

[0084] N,N'-di-[2-(methane-sulfonyloxy)phenyl]urea, N,N'-di-[2-(methane- sulfonyloxy)-4-methyl-phenyl]urea, N,N'-di-[2-(methane-sulfonyloxy)-4- ethyl-phenyl]urea, N,N'-di-[2-(methane-sulfonyloxy)-5-methyl-phenyl]urea, N,N'-di-[2-(methane-sulfonyloxy)-4,5-dimethyl-phenyl]urea, N,N'-di-[2- (ethane-sulfonyloxy)phenyl]urea, N,N'-di-[2-(ethane-sulfonyloxy)-4-methyl- phenyl]urea, N,N'-di-[2-(1-propane-sulfonyloxy)phenyl]urea, N,N'-di-[2-(2- propane-sulfonyloxy)phenyl]urea, N,N'-di-[2-(butane-sulfonyloxy)phenyl]urea, N,N'-di-[2-(pentane-sulfonyloxy)phenyl]urea, N,N'-di-[2-(hexane- sulfonyloxy)phenyl]urea, N,N'-di-[2-(cyclohexane-sulfonyloxy)phenyl]urea, N,N'-di-[2-(dodecane-sulfonyloxy)phenyl]urea,

[0085] N-[2-(ethane-sulfonyloxy)phenyl]-N'-[2-(propane-sulfonyloxy)phenyl]urea, N-[2-(ethane-sulfonyloxy)phenyl]-N'-[2-(hexane-sulfonyloxy)phenyl]urea,

[0086] N-[3-(phenylsulfonyloxy)phenyl]-N'-[4-(phenylsulfonyloxy)phenyl]urea, N-[3-(p-tolylsulfonyloxy)phenyl]-N'-[4'-(p-tolylsulfonyloxy)phenyl]urea, N-[3-(m-tolylsulfonyloxy)phenyl]-N'-[4-(m-tolylsulfonyloxy)phenyl]urea, N-[3-(o-tolylsulfonyloxy)phenyl]-N'-[3-(o-tolylsulfonyloxy)phenyl]urea,

[0087] N-[3-(p-xylene-sulfonyloxy)phenyl]-N'-[4-(p-xylene-sulfonyloxy)phenyl]urea, N-[3-(m-xylene-sulfonyloxy)phenyl]-N'-[4-(m-xylene-sulfonyloxy)phenyl]urea, N-[3-(mesitylene-sulfonyloxy)phenyl]-N'-[4-(mesitylene-sulfonyloxy)phenyl]urea,

[0088] N-[3-(2-naphthalenesulfonyloxy)phenyl]-N'-[3-(2-naphthalenesulfonyloxy)phenyl]urea,

[0089] N-[3-(p-ethylphenylsulfonyloxy)phenyl]-N'-[4-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[3-(p-propylphenylsulfonyloxy)phenyl]-N'-[4-(p-propylphenylsulfonyloxy)phenyl]urea, N-[3-(p-isopropylphenylsulfonyloxy)phenyl]-N'-[4-(p-isopropylphenylsulfonyloxy)phenyl]urea, N-[3-(p-tert-butylphenylsulfonyloxy)phenyl]-N'-[4-(p-tert-butylphenylsulfonyloxy)phenyl]urea,

[0090] N-[3-(p-methoxyphenylsulfonyloxy)phenyl]-N'-[4-(p-methoxyphenylsulfonyloxy)phenyl]urea, N-[3-(m-methoxyphenylsulfonyloxy)phenyl]-N'-[4-(m-methoxyphenylsulfonyloxy)phenyl]urea, N-[3-(o-methoxyphenylsulfonyloxy)phenyl]-N'-[4-(o-methoxyphenylsulfonyloxy)phenyl]urea, N-[3-(m,p-dimethoxyphenylsulfonyloxy)phenyl]-N'-[4-(m,p-dimethoxyphenylsulfonyloxy)phenyl]urea, N-[3-(p-ethoxyphenylsulfonyloxy)phenyl]-N'-[4-(p-ethoxyphenylsulfonyloxy)phenyl]urea, N-[3-(p-propoxyphenylsulfonyloxy)phenyl]-N'-[4-(p-propoxyphenylsulfonyloxy)phenyl]urea, N-[3-(p-butoxyphenylsulfonyloxy)phenyl]-N'-[4-(p-butoxyphenylsulfonyloxy)phenyl]urea,

[0091] N-[3-(p-cumylbenzylsulfonyloxy)phenyl]-N'-[4-(p-cumylbenzylsulfonyloxy)phenyl]urea, N-[3-(p-cumylphenylsulfonyloxy)phenyl]-N'-[4-(p-cumylphenylsulfonyloxy)phenyl]urea, N-[3-(o-phenylphenylsulfonyloxy)phenyl]-N'-[4-(o-phenylphenylsulfonyloxy)phenyl]urea, N-[3-(p-phenylphenylsulfonyloxy)phenyl]-N'-[4-(p-phenylphenylsulfonyloxy)phenyl]urea,

[0092] N-[3-(p-chlorophenylsulfonyloxy)phenyl]-N'-[4-(p-chlorophenylsulfonyloxy)phenyl]urea,

[0093] N-[3-(benzenesulfonyloxy)phenyl]-N'-[4-(p-toluenesulfonyloxy)phenyl]urea, N-[3-(p-toluenesulfonyloxy)phenyl]-N'-[4-(o-toluenesulfonyloxy)phenyl]urea, N-[3-(p-toluenesulfonyloxy)phenyl]-N'-[4-(benzenesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[4-(ethanesulfonyloxy)phenyl]urea, N-[3-(p-toluenesulfonyloxy)phenyl]-N'-[4-(benzylsulfonyloxy)phenyl]urea,

[0094] N-[3-(benzenesulfonyloxy)phenyl]-N'-[4-(benzenesulfonyloxy)phenyl]urea, N-[3-(phenylethanolsulfonyloxy)phenyl]-N'-[4-(phenylethanolsulfonyloxy)phenyl]urea, N-[3-(phenylpropanesulfonyloxy)phenyl]-N'-[4-(phenylpropanesulfonyloxy)phenyl]urea, N-[3-(p-methoxybenzylsulfonyloxy)phenyl]-N'-[4-(p-methoxybenzylsulfonyloxy)phenyl]urea,

[0095] N-[3-(benzenesulfonyloxy)phenyl]-N'-[4-(butanesulfonyloxy)phenyl]urea, N-[3-(benzenesulfonyloxy)phenyl]-N'-[4-(p-methylbenzylsulfonyloxy)phenyl]urea,

[0096] N-[3-(benzenesulfonyloxy)phenyl]-N'-[4-(benzenesulfonyloxy)phenyl]urea, N-[3-(phenylethanolsulfonyloxy)phenyl]-N'-[4-(phenylethanolsulfonyloxy)phenyl]urea, N-[3-(phenylpropanesulfonyloxy)phenyl]-N'-[4-(phenylpropanesulfonyloxy)phenyl]urea, N-[3-(p-methoxybenzylsulfonyloxy)phenyl]-N'-[4-(p-methoxybenzylsulfonyloxy)phenyl]urea,

[0097] N-[3-(benzenesulfonyloxy)phenyl]-N'-[4-(benzenesulfonyloxy)phenyl]urea, N-[3-(phenylethanolsulfonyloxy)phenyl]-N'-[4-(phenylethanolsulfonyloxy)phenyl]urea, N-[3-(phenylpropanesulfonyloxy)phenyl]-N'-[4-(phenylpropanesulfonyloxy)phenyl]urea, N-[3-(p-methoxybenzylsulfonyloxy)phenyl]-N'-[4-(p-methoxybenzylsulfonyloxy)phenyl]urea,

[0098] N-[2-(p-ethylphenylsulfonyloxy)phenyl]-N'-[4-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[2-(p-propylphenylsulfonyloxy)phenyl]-N'-[4-(p-propylphenylsulfonyloxy)phenyl]urea, N-[2-(p-isopropylphenylsulfonyloxy)phenyl]-N'-[4-(p-isopropylphenylsulfonyloxy)phenyl]urea, N-[2-(p-tert-butylphenylsulfonyloxy)phenyl]-N'-[4-(p-tert-butylphenylsulfonyloxy)phenyl]urea,

[0099] N-[2-(p-ethylphenylsulfonyloxy)phenyl]-N'-[4-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[2-(p-propylphenylsulfonyloxy)phenyl]-N'-[4-(p-propylphenylsulfonyloxy)phenyl]urea, N-[2-(p-isopropylphenylsulfonyloxy)phenyl]-N'-[4-(p-isopropylphenylsulfonyloxy)phenyl]urea, N-[2-(p-tert-butylphenylsulfonyloxy)phenyl]-N'-[4-(p-tert-butylphenylsulfonyloxy)phenyl]urea,

[0100] N-[2-(p-ethylphenylsulfonyloxy)phenyl]-N'-[4-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[2-(p-propylphenylsulfonyloxy)phenyl]-N'-[4-(p-propylphenylsulfonyloxy)phenyl]urea, N-[2-(p-isopropylphenylsulfonyloxy)phenyl]-N'-[4-(p-isopropylphenylsulfonyloxy)phenyl]urea, N-[2-(p-tert-butylphenylsulfonyloxy)phenyl]-N'-[4-(p-tert-butylphenylsulfonyloxy)phenyl]urea,

[0101] N-[2-(p-ethylphenylsulfonyloxy)phenyl]-N'-[4-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[2-(p-propylphenylsulfonyloxy)phenyl]-N'-[4-(p-propylphenylsulfonyloxy)phenyl]urea, N-[2-(p-isopropylphenylsulfonyloxy)phenyl]-N'-[4-(p-isopropylphenylsulfonyloxy)phenyl]urea, N-[2-(p-tert-butylphenylsulfonyloxy)phenyl]-N'-[4-(p-tert-butylphenylsulfonyloxy)phenyl]urea,

[0102] N-[2-(p-ethylphenylsulfonyloxy)phenyl]-N'-[4-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[2-(p-propylphenylsulfonyloxy)phenyl]-N'-[4-(p-propylphenylsulfonyloxy)phenyl]urea, N-[2-(p-isopropylphenylsulfonyloxy)phenyl]-N'-[4-(p-isopropylphenylsulfonyloxy)phenyl]urea, N-[2-(p-tert-butylphenylsulfonyloxy)phenyl]-N'-[4-(p-tert-butylphenylsulfonyloxy)phenyl]urea,

[0103] N-[2-(p-cumylbenzylsulfonyloxy)phenyl]-N'-[4-(p-cumylbenzylsulfonyloxy)phenyl]urea, N-[2-(p-cumylphenylsulfonyloxy)phenyl]-N'-[4-(p-cumylphenylsulfonyloxy)phenyl]urea, N-[2-(o-phenylphenylsulfonyloxy)phenyl]-N'-[4-(o-phenyl)phenylsulfonyloxyphenyl]urea, N-[2-(p-phenylphenylsulfonyloxy)phenyl]-N'-[4-(p-phenylphenylsulfonyloxy)phenyl]urea,

[0104] N-[2-(p-chlorophenylsulfonyloxy)phenyl]-N'-[4-(p-chlorophenylsulfonyloxy)phenyl]urea,

[0105] N-[2-(ethylsulfonyloxy)phenyl]-N'-[4-(phenylsulfonyloxy)phenyl]urea, N-[2-(ethylsulfonyloxy)phenyl]-N'-[4-(p-tolylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[4-(ethylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[4-(benzylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[4-(p-tolylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[4-(o-tolylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[4-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[4-(p-methoxyphenylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[4-[phenylsulfonyloxy]phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[4-(mesitylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[4-(1-naphthalenesulfonyloxy)phenyl]urea,

[0106] N-[2-(benzylsulfonyloxy)phenyl]-N'-[4-(benzylsulfonyloxy)phenyl]urea, N-[2-(phenylethanolsulfonyloxy)phenyl]-N'-[4-(phenylethanolsulfonyloxy)phenyl]urea, N-[2-(phenylpropanolsulfonyloxy)phenyl]-N'-[4-(phenylpropanolsulfonyloxy)phenyl]urea, N-[2-(p-methoxybenzylsulfonyloxy)phenyl]-N'-[4-(p-methoxybenzylsulfonyloxy)phenyl]urea,

[0107] N-[2-(ethylsulfonyloxy)phenyl]-N'-[4-(benzylsulfonyloxy)phenyl]urea, N-[2-(benzylsulfonyloxy)phenyl]-N'-[4-(methanesulfonyloxy)phenyl]urea, N-[2-(benzylsulfonyloxy)phenyl]-N'-[4-(butanesulfonyloxy)phenyl]urea,

[0108] N-[2-(methanesulfonyloxy)phenyl]-N'-[4-(methanesulfonyloxy)phenyl]urea, N-[2-(ethanesulfonyloxy)phenyl]-N'-[4-(ethanesulfonyloxy)phenyl]urea, N-[2-(1-propanesulfonyloxy)phenyl]-N'-[4-(1-propanesulfonyloxy)phenyl]urea, N-[2-(2-propanesulfonyloxy)phenyl]-N'-[4-(2-propanesulfonyloxy)phenyl]urea, N-[2-(butanesulfonyloxy)phenyl]-N'-[4-(butanesulfonyloxy)phenyl]urea, N-[2-(pentanesulfonyloxy)phenyl]-N'-[4-(pentanesulfonyloxy)phenyl]urea, N-[2-(hexanesulfonyloxy)phenyl]-N'-[4-(hexanesulfonyloxy)phenyl]urea, N-[2-(cyclohexanesulfonyloxy)phenyl]-N'-[4-(cyclohexanesulfonyloxy)phenyl]urea, N-[2-(dodecanesulfonyloxy)phenyl]-N'-[4-(dodecanesulfonyloxy)phenyl]urea,

[0109] N-[2-(methanesulfonyloxy)phenyl]-N'-[4-(propanesulfonyloxy)phenyl]urea, N-[2-(ethanesulfonyloxy)phenyl]-N'-[4-(propanesulfonyloxy)phenyl]urea, N-[2-(ethanesulfonyloxy)phenyl]-N'-[4-(butanesulfonyloxy)phenyl]urea,

[0110] N-[2-(phenylsulfonyloxy)phenyl]-N'-[3-(phenylsulfonyloxy)phenyl]urea, N-[2-(p-toluenesulfonyloxy)phenyl]-N'-[3-(p-toluenesulfonyloxy)phenyl]urea, N-[2-(m-toluenesulfonyloxy)phenyl]-N'-[3-(m-toluenesulfonyloxy)phenyl]urea, N-[2-(o-toluenesulfonyloxy)phenyl]-N'-[3-(o-toluenesulfonyloxy)phenyl]urea,

[0111] N-[2-(p-xenylsulfonyloxy)phenyl]-N'-[3-(p-xenylsulfonyloxy)phenyl]urea, N-[2-(m-xenylsulfonyloxy)phenyl]-N'-[3-(m-xenylsulfonyloxy)phenyl]urea, N-[2-(mesitylenesulfonyloxy)phenyl]-N'-[3-(phenylstyrenesulfonyloxy)phenyl]urea,

[0112] N-[2-(1-naphthalenesulfonyloxy)phenyl]-N'-[3-(1-naphthalenesulfonyloxy)phenyl]urea, N-[2-(2-naphthalenesulfonyloxy)phenyl]-N'-[3-(2-naphthalenesulfonyloxy)phenyl]urea,

[0113] N-[2-(p-ethylbenzenesulfonyloxy)phenyl]-N′-[3-(p-ethylbenzenesulfonyloxy)phenyl]urea, N-[2-(p-propylbenzenesulfonyloxy)phenyl]-N′-[3-(p-propylbenzenesulfonyloxy)phenyl]urea, N-[2-(p-isopropylbenzenesulfonyloxy)phenyl]-N′-[3-(p-isopropylbenzenesulfonyloxy)phenyl]urea, N-[2-(p-tert-butylbenzenesulfonyloxy)phenyl]-N′-[3-(p-tert-butylbenzenesulfonyloxy)phenyl]urea

[0114] N-[2-(p-methoxybenzenesulfonyloxy)phenyl]-N′-[3-(p-methoxybenzenesulfonyloxy)phenyl]urea, N-[2-(m-methoxybenzenesulfonyloxy)phenyl]-N′-[3-(m-methoxybenzenesulfonyloxy)phenyl]urea, N-[2-(o-methoxybenzenesulfonyloxy)phenyl]-N′-[3-(o-methoxybenzenesulfonyloxy)phenyl]urea, N-[2-(m,p-dimethoxybenzenesulfonyloxy)phenyl]-N N′-[3-(m, p-dimethoxybenzenesulfonyloxy)phenyl]urea, N-[2-(p-ethoxybenzenesulfonyloxy)phenyl)-N′-[3-(p-ethoxybenzenesulfonyloxy)phenyl]urea, N-[2-(p-propoxybenzenesulfonyloxy)phenyl]-N′-[3-(p-propoxybenzenesulfonyloxy)phenyl]urea, N-[2-(p-butoxybenzenesulfonyloxy)phenyl]-N′-[3-(p-butoxybenzenesulfonyloxy)phenyl]urea,

[0115] N-[2-(p-cumylbenzylsulfonyloxy)phenyl]-N′-[3-(p-cumylbenzylsulfonyloxy)phenyl]urea, N-[2-(p-cumylbenzylsulfonyloxy)phenyl]-N′-[3-(p-cumylbenzylsulfonyloxy)phenyl]urea, N-[2-(o-phenylbenzylsulfonyloxy)phenyl]-N′-[3-(o-phenylbenzylsulfonyloxy)phenyl]urea, N-[2-(p-phenylbenzylsulfonyloxy)phenyl]-N′-[3-(p-phenylbenzylsulfonyloxy)phenyl]urea

[0116] N-[2-(p-chlorobenzenesulfonyloxy)phenyl]-N′-[3-(p-chlorobenzenesulfonyloxy)phenyl]urea,

[0117] N-[2-(ethylsulfonyloxy)phenyl]-N'-[3-(p-tolylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[3-(ethylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[3-(benzylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[3-(p-tolylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[3-(o-tolylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[3-(p-ethylphenylsulfonyloxy)phenyl]urea, N-[2-(phenylsulfonyloxy)phenyl]-N'-[3-(p-methoxyphenylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[3-(phenylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[3-(mesitylsulfonyloxy)phenyl]urea, N-[2-(p-tolylsulfonyloxy)phenyl]-N'-[3-(1-naphthylsulfonyloxy)phenyl]urea,

[0118] N-[2-(benzylsulfonyloxy)phenyl]-N'-[3-(benzylsulfonyloxy)phenyl]urea, N-[2-(phenethylsulfonyloxy)phenyl]-N'-[3-(phenethylsulfonyloxy)phenyl]urea, N-[2-(phenylpropanesulfonyloxy)phenyl]-N'-[3-(phenylpropanesulfonyloxy)phenyl]urea, N-[2-(p-methoxybenzylsulfonyloxy)phenyl]-N'-[3-(p-methoxybenzylsulfonyloxy)phenyl]urea,

[0119] N-[2-(benzylsulfonyloxy)phenyl]-N'-[3-(methylsulfonyloxy)phenyl]urea, N-[2-(benzylsulfonyloxy)phenyl]-N'-[3-(butanesulfonyloxy)phenyl]urea,

[0120] N-[2-(methanesulfonyloxy)phenyl]-N'-[3-(methanesulfonyloxy)phenyl]urea, N-[2-(ethanesulfonyloxy)phenyl]-N'-[3-(ethanesulfonyloxy)phenyl]urea, N-[2-(1-propanesulfonyloxy)phenyl]-N'-[3-(1-propanesulfonyloxy)phenyl]urea, N-[2-(2-propanesulfonyloxy)phenyl]-N'-[3-(2-propanesulfonyloxy)phenyl]urea, N-[2-(butanesulfonyloxy)phenyl]-N'-[3-(butanesulfonyloxy)phenyl]urea, N-[2-(pentanesulfonyloxy)phenyl]-N'-[3-(pentanesulfonyloxy)phenyl]urea, N-[2-(hexanesulfonyloxy)phenyl]-N'-[3-(hexanesulfonyloxy)phenyl]urea, N-[2-(cyclohexanesulfonyloxy)phenyl]-N'-[3-(cyclohexanesulfonyloxy)phenyl]urea, N-[2-(dodecanesulfonyloxy)phenyl]-N'-[3-(dodecanesulfonyloxy)phenyl]urea,

[0121] N-[2-(methanesulfonyloxy)phenyl]-N'-[3-(propanesulfonyloxy)phenyl]urea, N-[2-(ethanesulfonyloxy)phenyl]-N'-[3-(propanesulfonyloxy)phenyl]urea, and N-[2-(ethanesulfonyloxy)phenyl]-N'-[3-(butanesulfonyloxy)phenyl]urea.

[0122] <Production method of compound represented by general formula (1)>

[0123] The compound represented by general formula (1) can be synthesized by a reaction between a compound represented by general formula (4) and an aromatic amine compound represented by general formula (5).

[0124] In addition, the compound represented by general formula (1) can be synthesized by a reaction between a compound represented by general formula (6) and an aromatic amine compound represented by general formula (7).

[0125] [Chemical Formula 3]

[0126] [Chemical Formula 4]

[0127] In general formulae (4) and (5), R1is an alkyl group or an aryl group; A1is a hydrogen atom or a C1-4alkyl group, in which two or more A1may be the same as or different from each other; and R2is a C1-12straight chain, branched chain, or alicyclic alkyl group, or a C7-12aralkyl group or a C6-12aryl group which is unsubstituted or substituted with a C1-12alkyl group, a C1-12alkoxy group, a C6-12aryl group, or a halogen atom.

[0128] [Chemical Formula 5]

[0129]

[0130] [Chemical Formula 6]

[0131]

[0132] In General Formulas (6) and (7), R1is an alkyl group or an aryl group; R is an alkyl group; and n is an integer of 0 to 3.

[0133] For example, the compound represented by General Formula (1) can be synthesized by the following method.

[0134] (Step 1)

[0135] 3-[(R) n -PhSO3]-Ph-NH2 / deoxidizing agent + XCOOR1→

[0136] 3-[(R) n -PhSO3]-Ph-NHCOOR1+ HX· deoxidizing agent

[0137] (Step 2)

[0138] 3-[(R) n -PhSO3]-Ph-NHCOOR1+ 3-[(R) n -PhSO3]-Ph-NH2 / base

[0139] → 3-{[(R) n -PhSO3]-Ph-NH}2=CO + R1OH

[0140] In the above formulae, R1is an alkyl group or an aryl group, R is an alkyl group, Ph is a phenyl group, and n is an integer of 0 to 3.

[0141] XCOOR1used in Step 1 of the above synthesis method is a halogenated carboxylate or a carboxylic acid diester, in which X is chloro-, bromo-, OMe, OEt, OPro, or OPh, and R1is an Me group, an Et group, a Pro group, or a Ph group. The Me group is a methyl group, the Et group is an ethyl group, the Pro group is a propyl group, and the Ph group is a phenyl group. XCOOR1is particularly preferably monochloromethyl carbonate, mono-chloroethyl carbonate, mono-chlorophenyl carbonate, diethyl carbonate, or diphenyl carbonate.

[0142] Examples of the alkyl group of R1and the alkyl group of R are the same as the examples of the alkyl group of R described above.

[0143] For this reaction, a deoxidizing agent and a base, such as an organic base and an inorganic base, can be used.

[0144] Examples of the inorganic base include LiOH, NaOH, KOH, NaHCO3, KHCO3, Na2CO3, K2CO3, MeONa, and EtONa.

[0145] Examples of the organic base include organic bases such as trimethylamine, triethylamine, tributylamine, pyridine, N,N-dimethylpyridine, and 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU). The base is preferably K2CO3, triethylamine, pyridine, N,N-dimethylpyridine, or 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU).

[0146] 3-[(R) n -PhSO3]-Ph-NH2may also be synthesized by direct O-sulfonation of 3-hydroxyaniline. Alternatively, 3-[(R) n -PhSO3]-Ph-NH2may be readily obtained by O-sulfonation of a p-nitrophenol compound followed by reduction of the nitro group.

[0147] 3-[(R) n Examples of 3-[(R) n -PhSO3]-Ph-NH2include 3-phenylsulfonyloxyaniline, 3-(p-tolyl)sulfonyloxyaniline, 3-(m-tolyl)sulfonyloxyaniline, 3-(o-tolyl)sulfonyloxyaniline, 3-(p-xyl) sulfonyloxyaniline, and 3-mesitylsulfonyloxyaniline. Of 3-[(R) n -PhSO3]-Ph-NH2, 3-phenylsulfonyloxyaniline or 3-(p-tolyl)sulfonyloxyaniline is preferred.

[0148] Typically, an aprotic solvent can be used as the reaction solvent, and the reaction can be performed at a reaction temperature of 0°C to 180°C. In the present disclosure, the reaction temperature is in the range of, for example, 0°C to 180°C, preferably 10°C to 100°C. The reaction solvent and the reaction temperature are appropriately selected depending on the boiling point of the solvent and the stability of the reaction product.

[0149] Examples of the aprotic solvent include aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene; halogenated hydrocarbons such as dichloromethane, chloroform, dichloroethane, and chlorobenzene; acetate esters such as ethyl acetate, propyl acetate, butyl acetate, phenyl acetate, and benzyl acetate; ether compounds such as diethyl ether, dimethoxyethane, diethoxyethane, diglyme, dioxane, tetrahydrofuran, and anisole; ketone compounds such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; acetonitrile; dimethyl sulfoamide, dimethyl sulfoxide; and dimethylimidazolidine.

[0150] Step 2 is performed by reacting 3-[(R) n -PhSO3]-Ph-NHCOOR obtained in Step 1 with 3-[(R) n -PhSO3]-Ph-NH2in the presence of a base.

[0151] The base, reaction solvent, and reaction temperature used in Step 2 are the same as the reaction conditions used in Step 1.

[0152] In order to simplify the reaction process, Step 1 and Step 2 can be simultaneously performed by using 2 equivalents or more of 3-[(R) n -PhSO3]-Ph-NH2.

[0153] In order to introduce a urea group, various methods of introducing a urea group have been proposed. For example, a method of introducing a urea group by using a metal catalyst (e.g., palladium and molybdenum) or carbonyl bisimidazole to introduce carbon monoxide has been proposed, but the proposed method is not necessarily suitable for industry due to the high price of the catalyst or reagent or the complexity of the process.

[0154] The N,N'-diphenylurea derivative represented by general formulae (1) to (3) can also be synthesized by reacting a dihydroxydiphenylurea represented by general formula (8) below with a sulfonating agent represented by general formula (9) below in the presence of aprotic solvent. In particular, in the case of synthesizing a symmetrical compound, the above production method, which includes synthesizing dihydroxydiphenylurea and then performing O-sulfonation, is the most versatile and also the most economical.

[0155] [Chemical Formula 7]

[0156]

[0157] In general formula (8), A1 is a hydrogen atom or a C1-4 alkyl group, in which two or more A1 can be the same as or different from each other.

[0158] [Chemical Formula 8]

[0159]

[0160] In general formula (9), R2 is a C1-12 straight chain, branched chain, or alicyclic alkyl group, or a C7-12 aralkyl group or a C6-12 aryl group which is unsubstituted or substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom; and X is a halogen atom.

[0161] In addition, the above production method can perform the production process of dihydroxydiphenylurea by reacting in a smooth slurry state by selecting a reaction solvent, and can continuously perform the reaction of the subsequent step without isolating the dihydroxydiphenylurea. Therefore, the above production method has an industrial advantage.

[0162] The N,N'-diphenylurea derivative represented by General Formulas (1) to (3) can also be synthesized by reacting an aminophenol compound represented by General Formula (8-1) with urea in the presence of an aprotic solvent, and then reacting with a sulfonating agent represented by General Formula (9). By the step of reacting the aminophenol compound represented by General Formula (8-1) with urea in the presence of an aprotic solvent, and the reaction is carried out in a slurry state, the production step of dihydroxydiphenylurea is smoothly carried out. Further, when the step of reacting dihydroxydiphenylurea with a sulfonating agent represented by General Formula (9) is carried out, it is not necessary to isolate dihydroxydiphenylurea.

[0163] [Chemical Formula 9]

[0164]

[0165] In General Formula (8-1), A1is a hydrogen atom or a C1-4alkyl group.

[0166] The reaction for synthesizing dihydroxydiphenylurea from an aminophenol and urea is carried out in an aprotic solvent at a reaction temperature of 80°C to 200°C, preferably 125°C to 180°C.

[0167] Examples of the aminophenol include 2-aminophenol, 3-aminophenol, 4-aminophenol, 2-amino-5-methylphenol, 2-amino-4-methylphenol, 2-amino-6-methylphenol, 2-amino-4,5-dimethylphenol, 2-methyl-5-aminophenol, 3-methyl-5-aminophenol, 2,3-dimethyl-5-aminophenol, 2,4-dimethyl-5-aminophenol, 2,6-dimethyl-5-aminophenol, 3,4-dimethyl-5-aminophenol, 2-methyl-4-aminophenol, 3-methyl-4-aminophenol, and 2,6-dimethyl-4-aminophenol.

[0168] Examples of the aprotic solvent include: hydrocarbons such as tetrahydronaphthalene, benzene, toluene, xylene, and mesitylene; halogenated hydrocarbons such as trichloroethylene, chlorobenzene, and dichlorobenzene; acetate esters such as ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, isoamyl acetate, amyl acetate, hexyl acetate, phenyl acetate, and benzyl acetate; ether compounds such as diethoxyethane, diglyme, triglyme, dioxane, tetrahydrofuran, and anisole; ketone compounds such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, phenyl ethyl ketone, and benzophenone; tertiary amines such as tributylamine, pyridine, dimethylpyridine, and diazabicycloundecene; and aprotic polar solvents such as acetonitrile, benzonitrile, dimethylformamide, dimethyl sulfoxide, dimethylimidazolidine, and dimethylacetamide. The above-listed solvents can be used alone or in combination.

[0169] The solvent is preferably an aprotic aqueous solvent having a boiling point of 110°C or higher, and particularly preferably an acetate ester having a higher boiling point than butyl acetate, or an aromatic hydrocarbon such as toluene and xylene.

[0170] Examples of the method of treatment after completion of the reaction include: (1) a method of cooling and filtering the reaction solution to separate the dihydroxydiphenylurea, and supplying the separated dihydroxydiphenylurea to a subsequent reaction; and (2) a method of cooling the reaction solution to the temperature of a subsequent reaction, and supplying the cooled reaction solution to the subsequent reaction without separating the dihydroxydiphenylurea.

[0171] Next, the O-sulfonation reaction of the dihydroxydiphenylurea can be performed by dropping a sulfonating agent into a reaction solution including the dihydroxydiphenylurea, a deoxidizing agent, and an aprotic solvent. Alternatively, the O-sulfonation reaction of the dihydroxydiphenylurea can be performed by dropping a deoxidizing agent into a reaction solution including the dihydroxydiphenylurea, a sulfonating agent, and an aprotic solvent.

[0172] As the reaction temperature of the O-sulfonation reaction, the O-sulfonation reaction is performed at a temperature of 0 to 200°C in the presence of the deoxidizing agent, and preferably at a temperature of 10°C to 150°C.

[0173] The O-sulfonation is performed using a halogenated sulfonyl compound or the like, and the halogenated sulfonyl compound is preferably a sulfonyl chloride compound. Examples thereof include ethanesulfonyl chloride, ethanesulfonyl chloride, n-propanesulfonyl chloride, isopropanesulfonyl chloride, butanesulfonyl chloride, benzylsulfonyl chloride, phenylsulfonyl chloride, p-toluenesulfonyl chloride, o-toluenesulfonyl chloride, p-xylene sulfonyl chloride, mesitylenesulfonyl chloride, p-ethylphenylsulfonyl chloride, p-methoxyphenylsulfonyl chloride, p-chlorophenylsulfonyl chloride, 1-naphthalenesulfonyl chloride, and 2-naphthalenesulfonyl chloride.

[0174] Examples of the deoxidizing agent include: organic bases such as trimethylamine, triethylamine, tributylamine, pyridine, and dimethylaminopyridine; inorganic bases such as lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, potassium hydrogen carbonate, sodium hydrogen carbonate, sodium carbonate, potassium carbonate, and calcium carbonate; and bases such as sodium hydride, sodium methoxide, and sodium ethoxide.

[0175] The solvent used in the O-sulfonation step of the dihydroxydiphenylurea is an aprotic solvent. The solvent is particularly preferably an acetate ester such as butyl acetate, isoamyl acetate, pentyl acetate, and hexyl acetate, or an aromatic hydrocarbon such as toluene, xylene, and mesitylene. As the reaction solvent, the solvent used in the previous step can be used alone, or a solvent mixture of two or more solvents, or a two-phase solvent system including water and an aprotic solvent that is not soluble in water can be used.

[0176] When the reaction is performed, the solvent and the reaction temperature can be appropriately selected in consideration of the boiling point of the solvent, the physical properties of the sulfonating agent, and the stability of the reaction product, depending on the reaction method.

[0177] The reaction solution after the reaction is completed can be washed with water to wash and remove the deoxidizing agent.

[0178] In a case where high purity is desired as the quality of the reaction product, crystal washing or recrystallization can be performed using an aromatic hydrocarbon (for example, benzene and toluene), an acetate (for example, ethyl acetate and isoamyl acetate), or an alcohol (for example, methanol, ethanol, and isopropanol).

[0179] The amount of the color developer is not particularly limited, and can be appropriately selected depending on the intended purpose. The amount of the color developer is preferably 1 part or more, but 20 parts or less by mass, with respect to 1 part by mass of the leuco dye, and more preferably 2 parts or more, but 10 parts or less by mass.

[0180] <<Leuco Dye>>

[0181] The leuco dye is not particularly limited, and can be appropriately selected from leuco dyes for a heat-sensitive recording medium depending on the intended purpose. Examples of the leuco dye include leuco compounds such as triphenylmethane-based dyes, fluoran-based dyes, phenothiazine-based dyes, gallein-based dyes, spiropyran-based dyes, and indolinophthalide-based dyes.

[0182] There are no particular restrictions on colorless dyes, and they can be appropriately selected according to the intended purpose. Examples include 3,3-bis(p-dimethylaminophenyl)phthalide, 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis(p-dimethylaminophenyl)-6-diethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3,3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluorane, 3-dimethylamino-5,7-dimethylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ethylamino)-6-methyl-7-aniline fluorane, 2- {N-(3′-trifluoromethylphenyl)amino}-6-diethylaminofluorane, 2-{3,6-bis(diethylamino)-9-(o-chloroanilino)xanthonyllactam benzoate}, 3-diethylamino-6-methyl-7-(m-trichloromethylanilino)fluorane, 3-diethylamino-7-(o-chloroanilino)fluorane, 3-pyrrolidinyl-6-methyl-7-anilinofluorane, 3-di-n-butylamino-7-o-chloroanilino)fluorane, 3-N-methyl-N,n-pentylamino-6-methyl-7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N,N-diethylamino)-5-methyl-7-(N,N-benzyl)amino)fluoran, benzoyl leuco methylene blue, 6'-chloro-8'-methoxy- benzindolyl-spiropyran, 6'-bromo-3'-methoxy-benzindolyl-spiropyran, 3-(2'-hydroxy- 4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide, 3-(2'-hydroxy- 4'-dimethylaminophenyl)-3-(2'-methoxy-5'-nitrophenyl)phthalide, 3-(2'-hydroxy- 4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide, 3-(2'-methoxy- 4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'-methylphenyl)phthalide, 3-(N- ethyl-N-tetrahydrofurfuryl)amino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-(2- ethoxypropyl)amino-6-methyl-7-anilinofluoran, 3-N-methyl-N-isobutyl-6-methyl-7- anilinofluoran, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluoran, 3- pyrrolidino-7-trifluoromethylanilino)fluoran, 3-diethylamino-5-chloro-7-(N- benzyl-trifluoromethylanilino)fluoran, 3-pyrrolidino-7-(di-p-chlorophenyl)methyl- fluoran, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-p- tolylamino)-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-(o-methoxycarbonyl- phenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3- diethylamino-7-piperidinofluoran, 2-chloro-3-(N-methyltolylamino)-7-(p-n- butylphenylamino)fluoran, 3-di-n-butylamino-6-methyl-7-anilinofluoran, 3,6- bis(dimethylamino)fluorene spiro(9,3')-6'-dimethylaminophthalide, 3-(N-benzyl-N- cyclohexylamino)-5,6-benz-7-α-naphthylamino-4'-bromofluoran, 3-diethylamino-6- chloro-7-anilinofluoran, 3-diethylamino-6-methyl-7-mesitidino-4',5'-benzofluoran, 3-N-methyl-N-isopropyl-6-methyl-7-anilinofluoran, 3-N-ethyl-N-isoamyl-6-methyl- 7-anilinofluoran, 3-diethylamino-6-methyl-7-(2',4'-dimethylanilino)fluorane, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilino fluorane, 3-diethylamino-5-chloro-7-(N-benzyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-(di-p-chlorophenyl)methylamino fluorane, 3-diethylamino-5-chloro-(α-phenylethylamino)fluorane, 3-(N-ethyl-p-toluidino)-7-(α-phenylethylamino)fluorane, 3-diethylamino-7-(o-methoxycarbonylphenylamino)fluorane, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluorane, 3-diethylamino-7-piperidinofluorane, 2-chloro-3-(N-methyl-toluidino)-7-(p-N-butylanilino)fluorane, 3,6-bis(diethylamino)fluorene spiro(9,3')-6'-dimethylaminophthaloperine, 3-(N-benzyl-N-cyclohexylamino)-5,6-benzo-7-α-naphthylamino-4'-bromo fluorane, 3-diethylamino-6-chloro-7-anilino fluorane, 3-N-ethyl-N-(-2-ethoxypropyl)amino-6-methyl-7-anilino fluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilino fluorane, 3-diethylamino-6-methyl-7-m-tritolyamino-4',5'-benzofluorane, 3-(p-dimethylaminophenyl)-3-{1,1-bis(p-dimethylaminophenyl)ethene-2-yl}phthaloperine, 3-(p-dimethylaminophenyl)-3-{1,1-bis(p-dimethylaminophenyl)ethene-2-yl}-6-dimethylaminophthaloperine, 3-(p-dimethylaminophenyl)-3-(1-p-dimethylaminophenyl-1-styryl-2-yl)phthaloperine, 2-o-chloroanilino-6-diethylaminofluorane, 2-anilino-3-methyl-6-diethylaminofluorane, 2-anilino-3-methyl-6-(N-ethyl-N-p-tolyl)aminofluorane, 3-N-cyclohexyl-N-methylamino-6-methyl-7-anilino fluorane, 3-(p-dimethylaminophenyl)-3-(1-p-dimethylaminophenyl-1-p-chlorostyryl-2-yl)-6-dimethylaminophthaloperine, 3-(4'-dimethylamino-2'-methoxy)-3-(1"-p-dimethylaminophenyl-1"-p-chlorophenyl-1",3"-butadiene-4"-yl)benzophthaloperine, 3-(4'-dimethylamino-2'-benzyloxy)-3-(1"-p-dimethylaminophenyl-1"-phenyl-1",3"-butadiene-4"-yl)benzophthaloperine, 3-dimethylamino-6-dimethylamino-fluorene-9-spiro-3'-(6'-dimethylamino)phthaloperine, 3,3-bis(2-(p-dimethylaminophenyl)-2-p-methoxyphenyl)ethenyl)-4,5,6,7-tetrachlorophthaloperine, 3-bis{1,1-bis(4-pyrrolidinophenyl)ethene-2-yl}-5,6-dichloro-4,7-dibromophthalide, bis(p-dimethylaminostyryl)-1-naphthalenesulfonylmethane, bis(p-dimethylaminostyryl)-1-p-tolylsulfonylmethane, and 6'-(diethylamino)-2'-(2-fluoroanilino)spiro[phthalan-3,9'-xanthene]. The above-listed examples can be used alone or in combination.

[0183] The amount of the electron-donating compound is not particularly limited, and can be appropriately selected depending on the intended purpose. The amount of the electron-donating compound is preferably 5% or more by mass but 40% or less by mass, and more preferably 10% or more by mass but 30% or less by mass, with respect to the total amount of the heat-sensitive recording layer.

[0184] <Styrene-acrylic resin>

[0185] The styrene-acrylic resin can be appropriately synthesized for use, or can be selected from commercial products. As a method of synthesis, for example, the styrene-acrylic resin can be produced by performing emulsion polymerization, dispersion polymerization, suspension polymerization, pulverization, or solution / bulk polymerization, followed by emulsification.

[0186] Examples of commercial products of the styrene-acrylic resin include: product names PDX-7357, PDX-7616A, PDX-7732, PDX-7741, PDX-7787, PDX-7734, PDX-7777, PDX-7615, HPD-71, and HPD-196 (all available from BASF SE); product names EK-15 and EK-61 (both available from SAIDEN CHEMICAL INDUSTRY CO., LTD.); and product names A-2092 and XK-110 (both available from DSM Coating Resins Ltd.).

[0187] The styrene-acrylic resin is preferably a resin emulsion. The resin emulsion refers to a state in which resin particles are dispersed in an aqueous medium, in which the resin particles can be in a solid or fluid state. The aqueous medium refers to a medium including water or a hydrophilic solvent as a component.

[0188] Examples of a method of dispersing the resin particles in the aqueous medium include: a forced emulsification method using a dispersant, and a self-emulsification method using a resin having an anionic group. In the case of forced emulsification, the dispersant can remain in an image formed with the ink, and thus the remaining dispersant can reduce the fastness of the image. Therefore, it is preferable to use the self-emulsification method.

[0189] The amount of the styrene-acrylic acid resin is not particularly limited, and can be appropriately selected depending on the intended purpose. The amount of the styrene-acrylic acid resin is preferably 1.0% or more by mass but 50.0% or less by mass, more preferably 10.0% or more by mass but 50.0% or less by mass, and even more preferably 20.0% or more by mass but 40.0% or less by mass, with respect to the total amount of the heat-sensitive recording layer.

[0190] In addition to the styrene-acrylic acid resin, other resins can be added as needed. Examples of the other resins that can be added include: polyvinyl alcohol resins; starch or derivatives of starch; cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose; water-soluble polymers such as sodium polyacrylate, polyvinylpyrrolidone, acrylamide-acrylate copolymer, styrene-acryl copolymer, acrylamide-acrylate-methacrylate terpolymer, styrene-maleic anhydride copolymer alkali metal salt, isobutylene-maleic anhydride copolymer alkali metal salt, polyacrylamide, sodium alginate, gelatin, and casein; emulsions of, for example, polyvinyl acetate resins, polyurethane resins, polyacrylic acid, polyacrylate, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, and ethylene-vinyl acetate copolymer; and latexes of, for example, styrene-butadiene copolymer and styrene-butadiene-acrylic acid copolymer. The above-listed examples can be used alone or in combination.

[0191] When the above other resins are added, the amount of the above other resins is preferably 100 parts or less by mass, more preferably 50 parts or less by mass, with respect to 100 parts by mass of the styrene-acrylic acid resin, in view of heat water resistance.

[0192] <Photo-thermal conversion material>

[0193] A photo-thermal conversion material is a material that absorbs laser light to convert the absorbed light into heat. Photo-thermal conversion materials are roughly classified into inorganic materials and organic materials.

[0194] Examples of the inorganic material include carbon black, metal borides, and particles of metal oxides of Ge, Bi, In, Te, Se, Cr, and the like. Among the above-listed examples, metal borides and metal oxides are preferred because they have large light absorption in the near-infrared wavelength range and small light absorption in the visible light wavelength range. For example, the metal borides and the metal oxides are preferably at least one selected from hexaboride, tungsten oxide compounds, antimony tin oxide (ATO), indium tin oxide (ITO), and zinc antimonite.

[0195] Examples of hexaborides include LaB6, CeB6, PrB6, NdB6, GdB6, TbB6, DyB6, HoB6, YB6, SmB6, EuB6, ErB6, TmB6, YbB6, LuB6, SrB6, CaB6, and (La, Ce)B6.

[0196] Examples of tungsten oxide compounds include tungsten oxide particles represented by the general formula: WyOz (with the proviso that W is tungsten, O is oxygen, and 2.2 ≦ z / y ≦ 2.999), and composite tungsten oxide particles represented by the general formula: MxWyOz (with the proviso that M is at least one element selected from the group consisting of H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I, W is tungsten, O is oxygen, 0.001 ≦ x / y ≦ 1, and 2.2 ≦ z / y ≦ 3.0) (see International Publication No. WO2005 / 037932 and Unexamined Japanese Patent Application Publication No. 2005-187323). Among the above-listed examples, a cesium-containing tungsten oxide is particularly preferred because it has a large absorption in the near-infrared wavelength range and a small absorption in the visible wavelength range.

[0197] Further, among antimony tin oxide (ATO), indium tin oxide (ITO), and zinc antimonate, ITO is preferred because it has a large absorption in the near-infrared wavelength range and a small absorption in the visible wavelength range.

[0198] The above-listed materials can be formed into a layer by vacuum vapor deposition or by adhering a particulate material with a resin, etc.

[0199] Various dyes can be used as the organic material as appropriate depending on the wavelength of light to be absorbed. In the case where a semiconductor laser is used as the light source, a near-infrared absorbing dye having an absorption peak at about 600 nm to about 1200 nm can be used. Specific examples of the near-infrared absorbing dye include cyanine dyes, quinone dyes, quinolone derivatives of indolynaphthol, phenylenediamine-based nickel complexes, and phthalocyanine dyes.

[0200] The above-listed light-to-heat conversion materials can be used alone or in combination.

[0201] The light-to-heat conversion material can be included in the heat-sensitive recording layer or in another layer of the non-heat-sensitive recording layer. In the case where the light-to-heat conversion material is included in a layer of the non-heat-sensitive recording layer, the layer including the light-to-heat conversion material is preferably disposed next to the heat-sensitive recording layer.

[0202] The amount of the photo-thermal conversion material relative to the heat-sensitive recording layer is preferably 0.1% or more but 10% or less by mass, and more preferably 0.3% or more but 5% or less by mass.

[0203] <<Other Components>>

[0204] Examples of the above-mentioned other components include auxiliary additives, hot-melt materials, lubricants, fillers, ultraviolet absorbers, antioxidants, sensitizers, light stabilizers, and crosslinking agents.

[0205] For example, as the auxiliary additive, various hindered phenol compounds or hindered amine compounds having electron-accepting properties but relatively low coloring ability can be added.

[0206] Examples of the auxiliary additives include 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-butylidenebis(6-tert-butyl-2-methylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 4,4'-thiobis(6-tert-butyl-2-methylphenol), tetrabromobisphenol A, tetrabromobisphenol S, 4,4-thiobis(2-methylphenol), 4,4'-thiobis(2-chlorophenol), tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate, and tetrakis(1,2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate. The above-listed examples can be used alone or in combination.

[0207] -Hot-Melt Materials-

[0208] Examples of the hot-melt material include fatty acids (e.g., stearic acid and behenic acid), fatty acid amides (e.g., stearic acid amide and palmitic acid amide), fatty acid metal salts (e.g., zinc stearate, aluminum stearate, calcium stearate, zinc palmitate, and zinc behenate), p-benzylbiphenyl, triphenylmethane, p-benzyloxybenzoic acid benzyl ester, β-benzyloxy naphthalene, β-naphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid phenyl ester, 1-hydroxy-2-naphthoic acid methyl ester, diphenyl carbonate, ethylene glycol carbonate, p-xylylene dibenzoate, p-xylylene dimethylate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzoxynaphthalene, 1,2-diphenoxyethane, 1,2-bis(3-methylphenoxy)ethane, 1,2-bis(4-methylphenoxy)ethane, 1,4-diphenoxy-2-butene, 1,2-bis(4-methoxyphenylthio)ethane, dibenzoylmethane, 1,4-diphenylthiobutane, 1,4-diphenylthio-2-butene, 1,3-bis(2-vinyloxyethoxy)benzene, 1,4-bis(2-vinyloxyethoxy)benzene, p-(2-vinyloxyethoxy)biphenyl, p-aryloxybiphenyl, p-propynoxybiphenyl, dibenzoyloxy methane, dibenzoyloxy propane, dibenzyl disulfide, 1,1-diphenylethanol, 1,1-diphenylpropanol, p-benzyloxybenzyl alcohol, 1,3-phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-octadecylcarbamoylbenzene, 1,2-bis(4-methoxyphenoxy)propane, 1,5-bis(4-methoxyphenoxy)-3-oxapentane, dibenzyl oxalate, bis(4-methylbenzyl)oxalate, and bis(4-chlorobenzyl)oxalate. The above-listed examples can be used alone or in combination.

[0209] - Lubricant -

[0210] Examples of the lubricant include higher fatty acids or metal salts of higher fatty acids, higher fatty acid amides, higher fatty acid esters, animal waxes, vegetable waxes, mineral waxes, petroleum waxes, and synthetic waxes. The above-listed examples can be used alone or in combination.

[0211] - Filler -

[0212] Examples of the filler include: inorganic powders such as calcium carbonate, silica, silica, zinc oxide, titanium oxide, zirconium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, kaolin, talc, surface-treated calcium, and surface-treated silica; and organic powders such as urea-formaldehyde resin, styrene-methyl methacrylate copolymer, polystyrene resin, and vinylidene chloride resin. The above-listed examples can be used alone or in combination.

[0213] The amount of the filler is not particularly limited, and can be appropriately selected depending on the intended purpose. The amount of the filler is preferably 0.4 parts or less by mass, and more preferably 0.2 parts or less by mass, relative to 1 part by mass of the binder resin.

[0214] -Crosslinking agent-

[0215] The crosslinking agent is not particularly limited, and can be appropriately selected depending on the intended purpose. Examples of the crosslinking agent include glyoxal derivatives, methylol derivatives, epichlorohydrin, polyamide epichlorohydrin, epoxy resins, aziridine compounds, hydrazine, hydrazine derivatives, oxazoline derivatives, and carbodiimide derivatives. The above-listed examples can be used alone or in combination.

[0216] -Ultraviolet absorber-

[0217] The ultraviolet absorber is not particularly limited, and can be appropriately selected depending on the intended purpose. Examples of the ultraviolet absorber include salicylic acid-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and benzotriazole-based ultraviolet absorbers.

[0218] Examples of the ultraviolet absorber include phenyl salicylate, p-tert-butylphenyl salicylate, p-octylphenyl salicylate, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, bis(2-methoxy-4-hydroxy-5-benzoylphenyl)methane, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-amylphenyl)benzotriazole, 2-{2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthalimidomethyl)-5'-methylphenyl}benzotriazole, 2,2'-methylenebis{4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol}, 2-(2'-hydroxy-5'-methylacryloyloxyphenyl)-2H-benzotriazole, 2-(3,5-di-tert-amyl-2-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, and 2-(5-methyl-2-hydroxyphenyl)benzotriazole. The above-listed examples can be used alone or in combination.

[0219] <Support>

[0220] The shape, structure, size, material, etc. of the support are not particularly limited and can be appropriately selected according to the intended purpose. Examples of the shape of the support include a flat plate and a sheet. The structure of the support can be a single-layer structure, or a multi-layer structure. The size of the support can be appropriately selected according to the size of the heat-sensitive recording medium, etc.

[0221] As the support, for example, in addition to typical paper, synthetic paper or a plastic film (such as polyethylene, transparent polyethylene terephthalate, polypropylene, and chlorovinyl) can be used. When a plastic film is used as the support, the support can be subjected to surface treatment such as matte treatment and corona treatment to improve the fixability of the coating liquid. Among the above-listed examples, a polyethylene terephthalate sheet formed by biaxial stretching is preferred due to its excellent strength, heat resistance, and dimensional stability. In addition, a white opaque film formed by adding a white raw material or a filler to a film, or a foamed sheet formed by foaming can also be used. In addition, a laminated material of the above-listed materials can also be used. Typical examples thereof include a laminated material of cellulose fiber and synthetic paper, a laminated material of cellulose fiber and a plastic film, and a laminated material of a plastic film and synthetic paper.

[0222] The support is preferably a transparent film in the field of POS systems for fresh foods, packaged meals, and prepared meals, because the contents can be visually recognized. In the present disclosure, the transparency is not particularly limited as long as the haze (turbidity), which is an index indicating the transparency of the film, is about 10% or less. In order to achieve the purpose of the present disclosure, the haze of the support is more preferably 5% or less.

[0223] The average thickness of the support can be appropriately adjusted as needed. In consideration of the transparency or processability, the average thickness of the support is preferably 3 micrometers or more but 500 micrometers or less, and more preferably 10 micrometers or more but 100 micrometers or less. When the average thickness of the support is less than 3 micrometers, the strength of the support can be insufficient. When the average thickness of the support is greater than 500 micrometers, the transparency of the support can be reduced, and the processability can also be reduced due to the excessively high rigidity of the support.

[0224] <Protective Layer>

[0225] The protective layer includes an adhesive resin and a crosslinking agent. The protective layer can further include other components as needed. The protective layer is preferably provided on or above the heat-sensitive layer.

[0226] The binder resin is not particularly limited, and can be appropriately selected depending on the intended purpose. Examples of the binder resin include: acrylic resins; polyvinyl alcohol resins; starch or derivatives of starch; cellulose derivatives such as hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose; water-soluble polymers such as sodium polyacrylate, polyvinylpyrrolidone, acrylamide-acrylate copolymer, styrene-acryl copolymer, acrylamide-acrylate-methacrylate terpolymer, styrene-maleic anhydride copolymer alkali metal salt, isobutylene-maleic anhydride copolymer alkali metal salt, polyacrylamide, sodium alginate, gelatin, and casein; emulsions of, for example, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate, and ethylene-vinyl acetate copolymer; and latexes (water-based emulsions) of, for example, styrene-butadiene copolymer and styrene-butadiene-acrylic acid copolymer. The above-listed examples can be used alone or in combination.

[0227] The cross-linking agent is not particularly limited, and can be appropriately selected depending on the intended purpose. Examples of the cross-linking agent include glyoxal derivatives, methylol derivatives, epichlorohydrin, polyamide epichlorohydrin, epoxy compounds, aziridine compounds, hydrazine, hydrazine derivatives, oxazoline derivatives, and carbodiimide derivatives. The above-listed examples can be used alone or in combination.

[0228] Further, the protective layer preferably includes a pigment (filler) as needed. Examples of the pigment used in the protective layer include: inorganic pigments such as zinc oxide, calcium carbonate, barium sulfate, titanium oxide, lithopone, talc, agalmatolite, kaolin, aluminum hydroxide, and calcined kaolin; and organic pigments such as cross-linked polystyrene resin, urea resin, silicone resin, cross-linked polymethyl methacrylate resin, and melamine-formaldehyde resin.

[0229] In addition to the above-described resin, water-proofing additive, and pigment, the protective layer can also include, in combination, an auxiliary additive component known in the art such as a surfactant, a hot-melt material, a lubricant, a pressure coloration inhibitor.

[0230] The protective layer is not particularly limited, and can be formed by any typical method known in the art.

[0231] The average thickness of the protective layer is not particularly limited, and can be appropriately selected depending on the intended purpose. The average thickness is preferably 0.5 micrometers or more but 5 micrometers or less, and more preferably 1 micrometer or more but 3 micrometers or less.

[0232] <Printed layer>

[0233] The print layer is formed by printing ink or the like. The print layer is formed in various colors, formed of any of various materials, and formed in any thickness. The print layer constitutes a background of an image printed on the heat-sensitive recording layer. Before the product is packaged, the product name, manufacturer name, ingredient label, or the like can be marked by providing the print layer. In addition, the print layer can provide an excellent design for the product.

[0234] The print layer is preferably provided on the heat-sensitive recording layer, or between the support and the heat-sensitive recording layer, or on the surface of the support opposite to the surface on which the heat-sensitive recording layer is provided.

[0235] The print layer includes a colorant, a binder resin, and a solvent, and can further include other components as necessary.

[0236] The colorant is not particularly limited, and can be appropriately selected depending on the intended purpose. As the colorant, a pigment or a dye can be used.

[0237] As the binder resin and the other components, those used in the heat-sensitive recording layer can be used.

[0238] The print layer can be formed by gravure printing, flexographic printing, offset printing, UV printing, or inkjet printing.

[0239] The average thickness of the print layer is not particularly limited, and can be appropriately selected depending on the intended purpose. The average thickness of the print layer is preferably 0.05 micrometers or more but 4 micrometers or less, and more preferably 0.1 micrometers or more but 2 micrometers or less.

[0240] <Other Layer>

[0241] The above other layer is not particularly limited, and can be appropriately selected depending on the intended purpose. Examples thereof include a back layer, a base layer, and a heat-seal layer.

[0242] -Back Layer-

[0243] The back layer can be optionally provided on the surface of the support opposite to the surface on which the heat-sensitive recording layer is provided.

[0244] The back layer includes a filler and a binder resin, and can further include other components such as a lubricant and a pigment as necessary.

[0245] As the filler, an inorganic filler or an organic filler can be used.

[0246] Examples of the inorganic filler include carbonates, silicates, metal oxides, and sulfuric acid compounds.

[0247] Examples of the organic filler include silicone resins, cellulose, epoxy resins, nylon resins, phenol resins, polyurethane resins, urea resins, melamine resins, polyester resins, polycarbonate resins, styrene resins, acrylic resins, polyethylene resins, formaldehyde resins, and polymethyl methacrylate resins.

[0248] The binder resin is not particularly limited, and can be appropriately selected depending on the intended purpose. For example, the binder resin used for the heat-sensitive recording layer can be used as the binder resin of the back layer.

[0249] The average thickness of the back layer is not particularly limited, and can be appropriately selected depending on the intended purpose. The average thickness of the back layer is preferably 0.1 micrometers or more but 20 micrometers or less, and more preferably 0.3 micrometers or more but 10 micrometers or less.

[0250] - bottom layer -

[0251] The bottom layer is not particularly limited, and can be appropriately selected depending on the intended purpose. The bottom layer includes a binder resin and hollow thermoplastic resin particles. The bottom layer preferably further includes other components as needed.

[0252] The hollow thermoplastic resin particles are micro-hollow particles in a foamed state. Each of the hollow thermoplastic resin particles includes a shell of a thermoplastic resin, and air or another gas inside the shell.

[0253] The average particle diameter (particle outer diameter) of the hollow thermoplastic resin particles is not particularly limited, and can be appropriately selected depending on the intended purpose. The average particle diameter of the hollow thermoplastic resin particles is preferably 0.2 micrometers or more but 20 micrometers or less, and more preferably 2 micrometers or more but 5 micrometers or less.

[0254] When the average particle diameter is less than 0.2 micrometers, it is technically difficult to make the particles hollow, and thus the function of the primer layer cannot be sufficiently exhibited. When the average particle diameter is more than 20 micrometers, the smoothness of the surface of the bottom layer after coating and drying is reduced, which leads to uneven coating of the heat-sensitive recording layer, and thus more than the required amount of heat-sensitive recording layer forming liquid is applied to make the coating uniform.

[0255] The void fraction of the hollow thermoplastic resin particles is not particularly limited, and can be appropriately selected depending on the intended purpose. The void fraction of the hollow thermoplastic resin particles is preferably 50% to 95%, and more preferably 80% to 95%.

[0256] When the void fraction is less than 30%, the heat-insulating performance of the bottom layer is insufficient, and thus the heat energy applied by the thermal head is released to the outside of the heat-sensitive recording medium via the carrier, which leads to insufficient effect of improving the sensitivity. The void fraction is the ratio of the outer diameter to the inner diameter (void diameter) of the hollow particles, and is represented by the following formula.

[0257] Void ratio (%) = (inner diameter of hollow particle / outer diameter of hollow particle) x 100

[0258] As described above, each of the hollow thermoplastic resin particles includes a shell of a thermoplastic resin. The thermoplastic resin is not particularly limited, and can be appropriately selected depending on the intended purpose. Examples of the thermoplastic resin include styrene-acrylic resin, polystyrene resin, acrylic resin, polyethylene resin, polypropylene resin, polyacetal resin, chlorinated polyether resin, polyvinyl chloride resin, and copolymer resin including vinylidene chloride and acrylonitrile as main components. Among the above-listed examples, styrene-acrylic resin and copolymer resin including vinylidene chloride and acrylonitrile as main components are preferred because the void ratio can be increased, the variation in particle diameter can be minimized, and the doctor blade coating can be appropriately applied at the time of coating.

[0259] The application amount of the hollow plastic particles is not particularly limited, and can be appropriately selected depending on the intended purpose. In order to maintain the sensitivity and uniformity of the coating layer, the amount thereof is preferably 1 g to 3 g with respect to 1 m 2 of the carrier. When the amount thereof is less than 1 g / m 2 , then sufficient sensitivity cannot be obtained. When the amount thereof is more than 3 g / m 2 , the cohesion of the base layer can be reduced.

[0260] - Heat-seal layer -

[0261] The heat-seal layer is formed by laminating a low-density polyethylene (LDPE) film serving as a sealing agent. Thus, the heat-seal layer can be melted by heating in a state where the heat-seal films are in close contact with each other. With the above-described property, the packaging sheet formed on the bag is sealed, that is, heat-sealed, by heating in the above-described state. Thus, the material for forming the heat-seal layer is not limited to LDPE, as long as the material is a heat-sealable material, that is, a heat-seal material.

[0262] As the heat-seal material, for example, a film of high-density polyethylene (HDPE), cast polypropylene (CPP), stretched polypropylene (OPP), and ethylene-vinyl acetate copolymer (EVA), or the like is appropriately used. In addition, a polyolefin resin (for example, polyethylene and polypropylene), a vinyl acetate-based resin (for example, an olefin-vinyl acetate copolymer such as ethylene-vinyl acetate copolymer), or an acrylic resin (for example, an olefin-(meth)acrylic acid copolymer such as ethylene-(meth)acrylic acid copolymer and ionomer and a metal crosslinked product thereof) can be used. In addition, any known heat-seal adhesive can also be used. In order to make the packaging product visible, a member that becomes transparent after molding is preferably used.

[0263] The average thickness of the heat-seal layer is preferably 5 micrometers or more but 50 micrometers or less, and more preferably 10 micrometers or more but 30 micrometers or less, in terms of transparency and seal strength.

[0264] (Heat-sensitive recording layer forming liquid)

[0265] The heat-sensitive recording layer forming liquid of the present disclosure includes a compound represented by any one of general formulae (1) to (3), a styrene-acrylic acid resin, and a solvent. The heat-sensitive recording layer forming liquid preferably further includes a leuco dye, and can further include other components as necessary.

[0266] As the leuco dye, the compound represented by any one of general formulae (1) to (3), the styrene-acrylic acid resin, and the other components, the above-described materials usable for the heat-sensitive recording layer can be used.

[0267] Examples of the solvent include water, an aromatic solvent, an ester solvent, a ketone solvent, an alcohol solvent, an aliphatic hydrocarbon, an ethylene glycol solvent, and a petroleum solvent including a paraffin or a naphthene as a main component and including 1% or less of an aromatic component. The above-described examples listed can be used alone or in combination.

[0268] Examples of the aromatic solvent include benzene, toluene, and xylene.

[0269] Examples of the ester solvent include methyl acetate, ethyl acetate, and isopropyl acetate.

[0270] Examples of the ketone solvent include acetone and methyl ethyl ketone.

[0271] Examples of the alcohol solvent include methanol, ethanol, isopropyl alcohol, and n-propanol.

[0272] Examples of the aliphatic hydrocarbon include n-hexane, n-heptane, and cyclohexane.

[0273] Examples of the ethylene glycol solvent include ethylene glycol and diethylene glycol.

[0274] The heat-sensitive recording layer forming liquid of the present disclosure can be produced by pulverizing and dispersing a leuco dye, a compound represented by any one of general formulae (1) to (3), a styrene-acrylic acid resin, and other components together by a dispersing machine such as a ball mill, a mill, and a sand mill until the particle diameter of the dispersed particles is 0.1 micrometers or more but 3 micrometers or less, optionally followed by compounding with other components.

[0275] (Method for producing heat-sensitive recording medium)

[0276] The method for producing the heat-sensitive recording medium of the present disclosure includes a heat-sensitive recording layer forming step. The heat-sensitive recording layer forming step includes applying the heat-sensitive recording layer forming liquid of the present disclosure to a support to form a heat-sensitive recording layer. The method can further include other steps as necessary.

[0277] The application method is not particularly limited, and can be appropriately selected according to the intended purpose. Examples of the application method include blade coating, gravure coating, gravure offset coating, bar coating, roll coating, knife coating, air knife coating, comma coating, U-comma coating, AKKU coating, smooth coating, microgravure coating, reverse roll coating, 4- or 5-roll coating, dip coating, curtain coating, slide coating, and die coating.

[0278] The amount of the heat-sensitive recording layer forming liquid after drying is not particularly limited, and can be appropriately selected according to the intended purpose. The amount thereof is preferably 1 g / m 2 or more but 20 g / m 2 or less, and more preferably 2 g / m 2 or more but 10 g / m 2 or less (dry basis).

[0279] The embodiment of the heat-sensitive recording medium of the present disclosure is not particularly limited, and can be appropriately selected according to the intended purpose. For example, the heat-sensitive recording medium can be used as a label as it is, or a layer of printed letters, marks, images, bar codes, or QR codes (registered trademark) can be provided on or above the protective layer or the support. In addition, an adhesive layer can be provided on the side of the support opposite to the side on which the heat-sensitive recording layer is present.

[0280] In addition, the shape of the heat-sensitive recording medium of the present disclosure is not particularly limited, and can be appropriately selected according to the intended purpose. Examples thereof include labels, sheets, and rolls.

[0281] <Use>

[0282] The heat-sensitive recording medium of the present disclosure can be used in various fields. The heat-sensitive recording medium can be used as a packaging film for various containers such as PET bottles for soft drinks, metal cans for coffee, bottles for energy drinks and medical products, and beer bottles, or a packaging label for the POS system field of fresh foods, packaged meals, and prepared meals.

[0283] Embodiments of the heat-sensitive recording medium of the present disclosure will be described with reference to the accompanying drawings. In the drawings, the same numbers represent the same constituent components, and overlapping description can be omitted. In addition, the number of the provided constituent components, the position at which the constituent components are provided, and the shape of the constituent components are not limited to the following embodiments, and any number, position, shape, etc. that are suitable for implementing the present disclosure can be selected.

[0284] <First Embodiment>

[0285] Figure 1 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to the first embodiment. The heat-sensitive recording medium of the first embodiment includes a support 1 and a heat-sensitive recording layer 2 provided on the support 1.

[0286] <Second Embodiment>

[0287] Figure 2 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to the second embodiment. The heat-sensitive recording medium of the second embodiment includes a support 1, and a heat-sensitive recording layer 2 and a protective layer 3 provided on the support 1 in this order.

[0288] <Third Embodiment>

[0289] Figure 3 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to the third embodiment. The heat-sensitive recording medium of the third embodiment includes a support 1, and a print layer 4 and a heat-sensitive recording layer 2 provided on the support 1 in this order.

[0290] <Fourth Embodiment>

[0291] Figure 4 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to the fourth embodiment. The heat-sensitive recording medium of the fourth embodiment includes a support 1, and a print layer 4, a heat-sensitive recording layer 2 and a protective layer 3 provided on the support 1 in this order.

[0292] <Fifth Embodiment>

[0293] Figure 5 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to the fifth embodiment. The heat-sensitive recording medium of the fifth embodiment includes a support 1, a heat-sensitive recording layer 2 provided on the support 1, and a print layer 4 provided on a surface of the support 1 on which the heat-sensitive recording layer is not provided.

[0294] <Sixth Embodiment>

[0295] Figure 6 is a schematic cross-sectional view illustrating an example of a heat-sensitive recording medium according to the sixth embodiment. The heat-sensitive recording medium of the sixth embodiment includes a support 1, a heat-sensitive recording layer 2 and a protective layer 3 provided on the support 1 in this order, and a print layer 4 provided on a surface of the support 1 on which the heat-sensitive recording layer is not provided.

[0296] <Seventh Embodiment>

[0297] Figure 7is a schematic cross-sectional view illustrating an example of a thermal recording medium according to the seventh embodiment. The thermal recording medium of the seventh embodiment includes a support 1, and a thermal recording layer 2 and a print layer 4 disposed in this order on the support 1.

[0298] <eighth embodiment>

[0299] Figure 8 is a schematic cross-sectional view illustrating an example of a thermal recording medium according to the eighth embodiment. The thermal recording medium of the eighth embodiment includes a support 1, and a thermal recording layer 2, a protective layer 3, and a print layer 4 disposed in this order on the support 1.

[0300] (image recording method)

[0301] The image recording method of the present disclosure includes heating the thermal recording medium of the present disclosure with a thermal head to record an image.

[0302] The shape, structure, size, and the like of the thermal head are not particularly limited, and can be appropriately selected according to the intended purpose.

[0303] In this case, in consideration of the preservability of the thermal recording layer and the conformity with the thermal head, it is preferable that a protective layer be provided on the thermal recording layer. If a color developer having high image and background preservability is used, it is not necessarily required to provide a protective layer, and the conformity with the thermal head can be imparted to the thermal recording layer directly by a filler, a lubricant, or the like.

[0304] When a filler is added in the protective layer or the thermal recording layer to achieve the conformity with the thermal head, if the 50% cumulative volume particle diameter (D 50 ) of the filler measured with a laser diffraction / scattering particle size analyzer (device name: LA-960, available from Horiba, Ltd.) is too small, the thermal head cannot be brought into close contact with the protective layer or the thermal recording layer, which is originally intended. When the particle diameter of the filler is too large, the thermal head is easily abraded, and it is not easy to secure the transparency. Therefore, the particle diameter of the filler is preferably in the approximate range of 0.25 micrometers to 0.75 micrometers, but is not limited thereto.

[0305] The image recording method of the present disclosure includes irradiating the thermal recording medium of the present disclosure with a laser to record an image.

[0306] Various units can be used as the heating unit using a laser, but it is preferable to use a laser capable of heating the thermal recording medium without contact.

[0307] The laser is not particularly limited, and can be appropriately selected depending on the intended purpose. For example, various laser devices generally known in the art, such as gas lasers using a gas (e.g., CO2), solid-state lasers using a solid (e.g., YAG and YVO4), and semiconductor lasers using a Group III-V semiconductor or a Group IV-VI semiconductor, can be used. The laser device used can be appropriately selected depending on the intended use and method.

[0308] In the above-mentioned example, the CO2 laser emits light having a wavelength of 10,000 nm, which is absorbed by general materials, and can be actively used in a method in which thermal recording is performed without any specific absorption material.

[0309] Further, when a light-to-heat conversion material, which is a material that absorbs laser light having a wavelength of 800 nm to 1,100 nm emitted from a semiconductor laser, a YAG solid layer, or a fiber layer to convert into heat, is added, laser light can be applied from the transparent film side in addition to directly applying laser light to the thermal recording layer, because transparent plastic films such as PET and OPP do not absorb laser light having a wavelength of 800 nm to 1,100 nm. Thus, laser light can be applied from the transparent film side to record a thermal recording layer provided on the opposite side of the film, which leads to thermal recording media having versatility in terms of use.

[0310] In the image forming step, the output of laser light emitted from the image forming apparatus is not particularly limited, and can be appropriately selected depending on the intended purpose. The output thereof is preferably 1 W or more, more preferably 3 W or more, and particularly preferably 5 W or more. When the output is less than 1 W, it can take a long time to form an image, and if the image formation time is shortened, the output becomes insufficient.

[0311] Further, the upper limit of the laser output is not particularly limited, and can be appropriately selected depending on the intended purpose. The upper limit thereof is preferably 200 W or less, more preferably 150 W or less, and particularly preferably 100 W or less. When the upper limit thereof is greater than 200 W, the size of the laser device used can be large.

[0312] Further, in the case of high-speed image recording on a thermal recording medium, it is preferable to use an image forming apparatus including a laser array in which laser emission elements are arranged in an array.

[0313] Next, as an example, a laser recording apparatus that records an image on a long thermal recording medium will be described.

[0314] Figure 9 is a schematic perspective view illustrating an image recording system 100 as a laser recording apparatus.

[0315] In the following description, the conveyance direction (traveling direction) of the thermal recording medium is described as the X-axis direction, the up-and-down direction is described as the Z-axis direction, and the direction orthogonal to the traveling direction and the up-and-down direction is described as the Y-axis direction.

[0316] As described below, the image recording system 100 irradiates the thermal recording medium 101 as a recording target with laser light to perform a surface processing treatment or an image recording process.

[0317] As Figure 9 As illustrated in FIG. 1, the image recording system 100 includes a conveyance device 10, a recording device 20, a main body 30, an optical fiber 42, and an encoder 60.

[0318] The recording device 20 is configured to irradiate a recording target with laser light to perform a processing treatment on the surface of the recording target or record an image as a visible image on the recording target. The recording device 20 corresponds to a laser irradiation device. The recording device 20 is disposed on the Y-axis direction side with respect to the conveyance device 10, specifically, in the Y direction along the conveyance path.

[0319] For example, the conveyance device 10 is configured to transport the thermal recording medium 101 as a recording target using a plurality of rotating rollers.

[0320] The main body 30 is connected to the conveyance device 10 and the recording device 20 and is configured to control the entire image recording system 100.

[0321] The encoder 60 is configured to acquire the traveling speed of the thermal recording medium 101.

[0322] Figure 10 is a schematic perspective view illustrating the structure of the image recording system 100.

[0323] The image recording system 100 includes a laser processing device 30 as a laser light source. The laser processing device 30 includes a laser irradiation device 14 and an optical unit 43. The laser irradiation device 14 includes a laser array unit 14a and a fiber array unit 14b. A fiber array recording device is used as the laser irradiation device 14. The fiber array recording device is configured to perform a surface treatment or image recording using a fiber array in which a plurality of optical fiber laser emitters are arrayed in a main scanning direction (Z-axis direction) orthogonal to a sub-scanning direction (X-axis direction) of the traveling direction of the thermal recording medium 101 serving as a recording target. The laser processing device 30 is configured to apply laser light emitted from a laser emitting element 41 to the thermal recording medium via the fiber array to record an image (visible image) formed by a drawing unit.

[0324] The laser array unit 14a includes a plurality of laser emission elements 41 arranged in an array, a cooling unit 50 configured to cool the laser emission elements 41, a plurality of driving drivers 45 configured to correspond to the laser emission elements 41 and configured to drive the corresponding laser emission elements 41, and a controller 46 configured to control the driving drivers 45. The controller 46 is connected to a power supply 48 configured to supply power to the laser emission elements 41 and an image information output unit 47, such as a personal computer, for outputting image information.

[0325] In the laser emission elements 41, energy that is not converted into laser light is converted into heat, and thus the laser emission elements 41 generate heat. Therefore, the laser emission elements 41 are cooled by the cooling unit 50 as a cooling device. Further, because the laser irradiation device 14 uses the fiber array unit 14b, the laser emission elements 41 can be provided separately from each other. Therefore, the heat influence of adjacent laser emission elements 41 can be minimized, and the laser emission elements 41 can be efficiently cooled. Thus, the temperature increase of each laser emission element 41 and the temperature variation of the laser emission elements 41 can be avoided, the variation in laser output can be minimized, and the density unevenness can be improved. The output of laser light is an average output measured by a power meter. There are two methods of controlling the output of laser light, which are a peak power control method and a pulse light emission ratio (duty ratio: laser emission time / period) control method.

[0326] The cooling unit 50 employs a liquid cooling system in which a coolant is circulated to cool the laser emission elements 41. The cooling unit 50 includes a heat receiving unit 51 in which the coolant receives heat from each of the laser emission elements 41 and a heat releasing unit 52 in which the heat of the coolant is released. The heat receiving unit 51 and the heat releasing unit 52 are connected to each other via cooling pipes 53a and 53b. The heat receiving unit 51 includes a housing formed of a high thermal conductive member and a cooling pipe formed of a high thermal conductive member, in which the cooling pipe is provided inside the housing and the coolant is circulated through the cooling pipe. The laser emission elements 41 are arranged in an array on the heat receiving unit 51.

[0327] The heat releasing unit 52 includes a heat sink and a pump for circulating the coolant. The coolant pumped out by the pump of the heat releasing unit 52 flows into the heat receiving unit 51 via the cooling pipe 53a. As the coolant travels through the cooling pipe inside the heat receiving unit 51, the coolant takes away the heat of the laser emission elements 41 arranged on the heat receiving unit 51 to cool the laser emission elements 41. The coolant, which is temperature-increased by absorbing the heat of the laser emission elements 41, flows out from the heat receiving unit 41 and travels inside the cooling pipe 53b to the heat sink of the heat releasing unit 52. The coolant is then cooled by the heat sink. The coolant cooled by the heat sink is pumped out to the heat receiving unit 51 by the pump.

[0328] The fiber array unit 14b includes optical fibers 42 and an array head 44. The optical fibers 42 are configured to correspond to the laser emitting element 41, and the array head 44 is configured to constrain the optical fibers 42 arranged in an array along the vertical direction (Z-axis direction) around the laser emitting section 42a of the optical fibers 42. The laser receiving section of each optical fiber 42 is disposed on the laser emitting surface of the corresponding laser emitting element 41.

[0329] When all the optical fibers 42 are constrained by a single array head 44, the array head 44 becomes elongated and easily deformed. Therefore, it is difficult to maintain a straight, linear beam alignment and uniform beam spacing using only one array head 44. Thus, each array head 44 can constrain 100 to 200 optical fibers 42. The laser irradiation device 14 preferably includes multiple array heads 44, each constraining 100 to 200 optical fibers 42, wherein the array heads 44 are arranged and positioned along the Z-axis direction, which is orthogonal to the direction of travel of the thermal recording medium 101.

[0330] Figure 11 This is a view illustrating the arrangement of a laser array. For example... Figure 11 The diagram in the middle, Figure 10 The optical fibers 42 of the central array head 44 are arranged to continuously link points of diameter R1 formed by the emitted laser at the focal point formed by the focusing of the optical unit 43, so as to color the thermal recording medium.

[0331] As the scanning direction of the laser, there are a main scanning direction and a sub-scanning direction, and the main scanning direction and the sub-scanning direction are orthogonal to each other. The main scanning direction is the direction in which the multiple optical fibers 42 are arranged. The sub-scanning direction is the direction of travel of the thermal recording medium.

[0332] Since the image is recorded on the thermal recording medium by moving the array head 44 relative to the thermal recording medium, the array head 44 can move relative to the thermal recording medium, or the thermal recording medium can move relative to the array head 44. Even when the array head 44 moves relative to the thermal recording medium, the phrase "the speed of travel of the thermal recording medium" is used with the array head 44 as the point of observation.

[0333] In addition, such as Figure 10 As illustrated, optical unit 43 (an example of an optical system) includes a collimating lens 43a and a condenser lens 43b. Collimating lens 43a is configured to convert the diffused flux of the laser emitted from optical fiber 42 into a parallel optical flux, and condenser lens 43b is configured to focus the laser to irradiate the surface of the thermal recording medium, which serves as the laser irradiation surface. Whether or not optical unit 43 is provided can be appropriately determined according to the intended purpose.

[0334] The image information output unit 47 (such as a personal computer) is configured to input image information to the controller 46. The controller 46 is configured to generate a drive signal (control pulse) for driving each driver 45 based on the input image information. The controller 46 is configured to transmit the generated drive signal (control pulse) to each driver 45. Specifically, the controller 46 includes a clock generator. When the clock frequency at which the clock generator oscillates reaches a predetermined clock frequency, the controller 46 transmits the drive signal (control pulse) of each driver 45 to the driver 45.

[0335] Once each driver 45 receives the drive signal (control pulse), the driver 45 sends a current pulse to drive the corresponding laser emission element 41. Under the drive of the driver 45, the laser emission element 41 outputs a light emission pulse to emit laser light. The laser light emitted from the laser emission element 41 enters the corresponding optical fiber 42 to be emitted from the laser emission portion 42a of the optical fiber 42. The laser light emitted from the laser emission portion 42a of the optical fiber 42 passes through the collimator lens 43a and the condenser lens 43b of the optical unit 43, and then is applied to the heat-sensitive recording medium as a recording target. The heat-sensitive recording medium is heated by the applied laser light to record an image on the heat-sensitive recording medium.

[0336] When using an apparatus configured to deflect laser light with a galvanometer mirror to record an image on a recording target, by rotating the galvanometer mirror, the laser light is applied to record an image, such as a letter, in one stroke. Therefore, in the case where a certain amount of information is recorded in the recording target, the recording speed does not catch up with the traveling speed of the recording target unless the transmission of the recording target is stopped.

[0337] Meanwhile, the laser irradiation apparatus 14 uses a laser array in which a plurality of laser emission elements 41 are arranged in an array, and thus can record an image on a heat-sensitive recording medium by controlling the on and off of the laser emission elements of each pixel. Therefore, even if the amount of information to be recorded is large, an image can be recorded on a heat-sensitive recording medium without stopping the transmission of the heat-sensitive recording medium. Therefore, even when a large amount of information is recorded in a recording target, using the laser irradiation apparatus 14 enables image recording without reducing productivity.

[0338] The laser irradiation device 14 is configured to apply laser light to the heat-sensitive recording medium to heat the heat-sensitive recording medium, thereby recording an image on the heat-sensitive recording medium. Therefore, it is desirable that the laser irradiation device 14 has a laser emission element 41 with a relatively high output. For this reason, the laser emission element 41 generates a large amount of heat. In a conventional laser array recording device without the fiber array unit 14b, it is desirable that the laser emission elements 41 are arranged in an array with a pitch corresponding to the resolution. Therefore, in order to achieve a resolution of 200 dpi, in the conventional laser array recording device, the laser emission elements 41 are arranged with a very narrow pitch. Therefore, the heat generated by the laser emission elements 41 is not easily released within the conventional laser array recording device, and the laser emission elements 41 are easily heated at a high temperature. As the temperature of the laser emission elements 41 in the conventional laser array recording device increases, the wavelength of light emitted by the laser emission elements 41 or the light output of the laser emission elements 41 fluctuates, and therefore the laser array recording device cannot heat a recording target to a predetermined temperature. Therefore, an excellent image cannot be obtained. In order to suppress such a temperature rise of the laser emission elements 41 of the conventional laser array recording device, it is important to ensure that there is a sufficient gap between emissions of the laser emission elements 41 by reducing the conveyance speed of the recording target, and therefore it is not possible to sufficiently improve the productivity.

[0339] Typically, the cooling unit 50 generally employs a chiller system. In the chiller system, only cooling is performed without heating. Therefore, the temperature of the light source does not exceed the set temperature of the chiller, but the temperature of the cooling unit 50 and the temperature of the laser emission elements 41 in contact with the cooling unit 50 fluctuate depending on the ambient temperature. Meanwhile, when a semiconductor laser is used as the laser emission element 41, the laser output varies depending on the temperature of the laser emission element 41 (the laser output is high when the temperature of the laser emission element 41 is low). Therefore, in order to control the laser output, it is preferable to measure the temperature of the laser emission element 41 or the temperature of the cooling unit 50, and based on the measured temperature, control the input signal of the driver 45 for controlling the laser output to make the laser output constant, thereby performing regular image formation.

[0340] On the other hand, the laser irradiation device 14 is a fiber array recording device using a fiber array unit 14b. Since the fiber array recording device is used, the laser emission portions 42a of the fiber array unit are arranged at a pitch corresponding to the resolution, and it is not necessary to arrange the laser emission elements of the laser array unit 14a at a pitch corresponding to the image resolution. Therefore, the heat of the laser emission elements 41 of the laser irradiation device 14 is sufficiently released, and it is possible to make the pitch of the laser emission elements 41 sufficiently wide. According to the laser irradiation device 14, it is possible to prevent the laser emission elements 41 from being heated to a high temperature, and it is possible to prevent the variation of the wavelength or the output of the laser emission elements 41. Therefore, the laser irradiation device 14 can record an excellent image on the thermosensitive recording medium. Even when the emission pitch of the laser emission elements 41 is shortened, it is possible to prevent the temperature of the laser emission elements 41 from rising, and thus the running speed of the thermosensitive recording medium is improved, and thus the productivity is improved.

[0341] Since the cooling unit 50 is provided in the laser irradiation device 14 to cool the laser emission elements 41 with a liquid, it is possible to further prevent the temperature of the laser emission elements 41 from rising. Therefore, the laser irradiation device 14 can further shorten the emission pitch of the laser emission elements 41, and it is possible to improve the running speed of the thermosensitive recording medium, and thus the productivity is improved. In the laser irradiation device 14, the laser emission elements 41 are cooled with a liquid, but it is also possible to cool the laser emission elements 41 with air by a cooling fan or the like. However, the liquid cooling has an advantage that the liquid cooling has a higher cooling efficiency than the air cooling, and it is possible to cool the laser emission elements 41 well. On the other hand, the air cooling has an advantage that although the air cooling has a lower cooling efficiency than the liquid cooling, it is possible to cool the laser emission elements 41 at a low cost.

[0342] Embodiment

[0343] The present disclosure will be described more specifically by way of examples below. The present disclosure should not be construed as being limited to only these examples.

[0344] The compounds of Nos. 1 to 5 used in the following examples were synthesized in the same manner as the synthesis example disclosed in Japanese Patent No. 6751479.

[0345] (Example 1)

[0346] <Production of thermosensitive recording medium>

[0347] -Preparation of dye dispersion-

[0348] A No. 1 compound represented by the following structural formula (36 parts by mass), an aqueous solution of a carboxyl group-containing acrylic resin (styrene-acrylic resin, product name: HPD-196, solid content: 36% by mass, available from BASF SE) (10 parts by mass), a surfactant (product name: PD-001, solid content: 10% by mass, available from Nissin Chemical Co., Ltd.) (3.6 parts by mass), and ion exchange water (50.4 parts by mass) were admixed and dispersed by a sand mill until the 50% cumulative volume particle diameter (D 50 ) of the dispersed components, measured by a laser diffraction / scattering particle size analyzer (device name: LA-960, available from Horiba, Ltd.), was 0.2 micrometers or less, thereby obtaining a dye dispersion liquid.

[0349] -Preparation of a color developer dispersion liquid-

[0350] A No. 1 compound represented by the following structural formula (36 parts by mass), an aqueous solution of a carboxyl group-containing acrylic resin (styrene-acrylic resin, product name: HPD-196, solid content: 36% by mass, available from BASF SE) (10 parts by mass), a surfactant (product name: PD-001, solid content: 10% by mass, available from Nissin Chemical Co., Ltd.) (3.6 parts by mass), and ion exchange water (50.4 parts by mass) were admixed and dispersed by a sand mill until the 50% cumulative volume particle diameter (D 50 ) of the dispersed components, measured by a laser diffraction / scattering particle size analyzer (device name: LA-960, available from Horiba, Ltd.), was 0.2 micrometers, thereby obtaining a color developer dispersion liquid.

[0351] <1st Compound>

[0352] [Chemical Formula 10]

[0353]

[0354] -Preparation of a thermosensitive recording layer forming liquid-

[0355] Next, 12.4 parts by mass of the obtained dye dispersion liquid, 37.3 parts by mass of the color developer dispersion liquid, 21.8 parts by mass of an acrylic emulsion (styrene-acrylic resin, product name: EK-61, solid content: 41% by mass, available from SAIDEN CHEMICAL INDUSTRY CO., LTD.), and 28.5 parts by mass of ion exchange water were admixed and stirred, thereby obtaining a thermosensitive recording layer forming liquid.

[0356] - Formation of a heat-sensitive recording layer -

[0357] Next, a heat-sensitive recording layer forming liquid was applied to one side of a polyethylene terephthalate film (product name: E5100, average thickness: 50 micrometers, available from TOYOBO CO., LTD., haze: 4.5) by a bar coater so that the deposition amount thereof was 4.0 g / m 2 (dry basis), followed by drying, thereby producing a heat-sensitive recording medium 1.

[0358] The haze of the polyethylene terephthalate film was a value measured by a haze meter (device name: HZ-V3, available from Suga Test Instruments Co., Ltd.).

[0359] (Example 2)

[0360] A color developer dispersion liquid was prepared in the same manner as in Example 1, except that the No. 1 compound was replaced with a No. 2 compound represented by the following structural formula in the preparation of the color developer dispersion liquid of Example 1.

[0361] Next, a heat-sensitive recording medium 2 was produced in the same manner as in Example 1, except that the above-prepared color developer dispersion liquid was used for forming a heat-sensitive recording layer.

[0362] <2nd Compound>

[0363] [Chemical Formula 11]

[0364]

[0365] (Example 3)

[0366] A color developer dispersion liquid was prepared in the same manner as in Example 1, except that the No. 1 compound was replaced with a No. 3 compound represented by the following structural formula in the preparation of the color developer dispersion liquid of Example 1.

[0367] Next, a heat-sensitive recording medium 3 was produced in the same manner as in Example 1, except that the above-prepared color developer dispersion liquid was used for forming a heat-sensitive recording layer.

[0368] <3rd Compound>

[0369] [Chemical Formula 12]

[0370]

[0371] (Example 4)

[0372] A color former dispersion liquid was produced in the same manner as in Example 1, except that in the production of the color former dispersion liquid of Example 1, the No. 1 compound was replaced with a No. 4 compound represented by the following structural formula.

[0373] Next, a heat-sensitive recording medium 4 was produced in the same manner as in Example 1, except that the above-prepared color former dispersion liquid was used to form the heat-sensitive recording layer.

[0374] <4th Compound>

[0375] [Chemical Formula 13]

[0376]

[0377] (Example 5)

[0378] A color former dispersion liquid was produced in the same manner as in Example 1, except that in the production of the color former dispersion liquid of Example 1, the No. 1 compound was replaced with a No. 5 compound represented by the following structural formula.

[0379] Next, a heat-sensitive recording medium 5 was produced in the same manner as in Example 1, except that the above-prepared color former dispersion liquid was used to form the heat-sensitive recording layer.

[0380] <5th Compound>

[0381] [Chemical Formula 14]

[0382]

[0383] (Example 6)

[0384] A heat-sensitive recording medium 6 was produced in the same manner as in Example 1, except that a protective layer was formed by applying a protective layer coating liquid described below to the heat-sensitive recording layer by a bar coater so that the deposition amount thereof was 2.0 g / m 2 (dry basis).

[0385] <Production of Protective Layer Coating Liquid>

[0386] Calcium carbonate (40.7 parts by mass), an aqueous solution of a carboxyl group-containing acrylic resin (styrene-acrylic resin, product name: HPD-196, solid content: 36% by mass, available from BASF SE) (11.3 parts by mass), a surfactant (product name: PD-001, solid content: 10% by mass, available from Nissin Chemical Co., Ltd.) (2 parts by mass), and ion exchange water (46 parts by mass) were admixed and dispersed by a sand mill until the 50% cumulative volume particle diameter (D50) of the dispersed components, measured by a laser diffraction / scattering particle size analyzer (device name: LA-960, available from Horiba, Ltd.), was 0.2 micrometers or less, thereby obtaining a dispersion liquid. 50 ) for 0.2 micrometers or less, thereby obtaining a dispersion liquid.

[0387] Next, 19.9 parts by mass of the obtained dispersion liquid, 21.9 parts by mass of an acrylic emulsion (styrene-acrylic resin, product name: EK-61, solid content: 41% by mass, available from SAIDEN CHEMICAL INDUSTRY CO., LTD.), 9.2 parts by mass of an oxazoline group-containing polymer emulsion (product name: WS-500, solid content: 39% by mass, available from NIPPON SHOKUBAI CO., LTD.), 4.5 parts by mass of an oxidized polyethylene wax dispersion liquid (solid content: 30% by mass), and 44.5 parts by mass of ion exchange water were admixed and stirred, thereby obtaining a protective layer coating liquid.

[0388] (Example 7)

[0389] A dye dispersion liquid was prepared in the same manner as in Example 1, except that 3-di-n-butylamino-6-methyl-7-anilinofluorane was replaced with 6'-(diethylamino)-2'-(2-fluoroanilino)spiro[phthalophiran-3,9'-xanthene] in the preparation of the dye dispersion liquid of Example 1.

[0390] Next, a heat-sensitive recording medium 7 was produced in the same manner as in Example 1, except that the above-prepared color developer dispersion liquid was used to form the heat-sensitive recording layer.

[0391] (Example 8)

[0392] A heat-sensitive recording medium 8 was produced in the same manner as in Example 1, except that the heat-sensitive recording layer was formed by using the following heat-sensitive recording layer-forming liquid.

[0393] <Heat-sensitive recording layer-forming liquid>

[0394] The dye dispersion liquid prepared in Example 1 (6.7 parts by mass), 20 parts by mass of the color developer dispersion liquid prepared in Example 1, 5.9 parts by mass of an acrylic emulsion (styrene-acrylic resin, product name: EK-61, solid content: 41% by mass, available from SAIDEN CHEMICAL INDUSTRY CO., LTD.), 24.1 parts by mass of an itaconic acid-modified polyvinyl alcohol aqueous solution (product name: KURARAY POVAL 25-88KL, solid content: 10% by mass, available from KURARAY CO., LTD.), and 43.4 parts by mass of ion exchange water were admixed and stirred, thereby preparing a thermosensitive recording layer-forming liquid.

[0395] (Example 9)

[0396] A thermosensitive recording medium 9 was produced in the same manner as in Example 1, except that a thermosensitive recording layer was formed by using the following thermosensitive recording layer-forming liquid.

[0397] <Thermosensitive recording layer-forming liquid>

[0398] The dye dispersion liquid prepared in Example 1 (12 parts by mass), 36.2 parts by mass of the color developer dispersion liquid prepared in Example 1, 21.2 parts by mass of an acrylic emulsion (styrene-acrylic resin, product name: EK-61, solid content: 41% by mass, available from SAIDEN CHEMICAL INDUSTRY CO., LTD.), 3 parts by mass of a cesium tungsten oxide dispersion liquid (product name: YMW-D20, solid content: 28.5% by mass, available from Sumitomo Metal Mining Co., Ltd.) used as a light-heat conversion material, and 27.6 parts by mass of ion exchange water were admixed and stirred, thereby preparing a thermosensitive recording layer-forming liquid.

[0399] (Example 10)

[0400] A thermosensitive recording medium 10 was produced in the same manner as in Example 1, except that a printing ink (product name: FINART R794 White G8, solid content: 42% by mass, available from DIC Graphics Corporation) was applied to the surface of the support by a rod coater so that the deposited amount of the ink was 1.0 g / m 2 (dry basis), thereby forming a printing layer.

[0401] (Comparative Example 1)

[0402] A color developer dispersion liquid was prepared in the same manner as in Example 1, except that in the preparation of the color developer dispersion liquid of Example 1, Compound No. 1 was replaced with N-[2-[[(phenylamino)carbonyl]amino]phenyl]phenylsulfonamide (product name: NKK-1304, available from Nippon Soda Co., Ltd.).

[0403] Next, a heat-sensitive recording medium 11 was produced in the same manner as in Example 1, except that the above-prepared color developer dispersion liquid was used for forming the heat-sensitive recording layer.

[0404] (Comparative Example 2)

[0405] A color developer dispersion liquid was prepared in the same manner as in Example 1, except that in the preparation of the color developer dispersion liquid of Example 1, Compound No. 1 was replaced with 4-methyl-N-[[[3-[[(4-methylphenyl)sulfonyl]oxy]phenyl]amino]carbonyl]benzenesulfonamide (product name: P-201, available from BASF SE).

[0406] Next, a heat-sensitive recording medium 12 was produced in the same manner as in Example 1, except that the above-prepared color developer dispersion liquid was used for forming the heat-sensitive recording layer.

[0407] (Comparative Example 3)

[0408] A color developer dispersion liquid was prepared in the same manner as in Example 1, except that in the preparation of the color developer dispersion liquid of Example 1, Compound No. 1 was replaced with 4-hydroxy-4'-isopropoxydiphenylsulfone (product name: D-8, available from Nippon Soda Co., Ltd.).

[0409] Next, a heat-sensitive recording medium 13 was produced in the same manner as in Example 1, except that the above-prepared color developer dispersion liquid was used for forming the heat-sensitive recording layer.

[0410] (Comparative Example 4)

[0411] A color developer dispersion liquid was prepared in the same manner as in Example 1, except that in the preparation of the color developer dispersion liquid of Example 1, Compound No. 1 was replaced with bis(4-hydroxyphenyl)sulfone mono-methallyl ether (product name: BPS-MAE, available from NICCA CHEMICAL CO., LTD.).

[0412] Next, a heat-sensitive recording medium 14 was produced in the same manner as in Example 1, except that the above-prepared color developer dispersion liquid was used for forming the heat-sensitive recording layer.

[0413] (Comparative Example 5)

[0414] A dye dispersion liquid and a color developer dispersion liquid were prepared in the same manner as in Example 1, except that in the preparation of the dye dispersion liquid and the color developer dispersion liquid, 10 parts by mass of the carboxyl group-containing acrylic resin aqueous solution (styrene-acrylic resin, product name: HPD-196, solid content: 36% by mass, available from BASF SE) was replaced with 18 parts by mass of a polyvinyl alcohol aqueous solution (product name: GOSENX L-3266, solid content: 30% by mass, available from Nippon Synthetic Chemical Industry Co., Ltd.), and the amount of ion exchange water was changed from 50.4 parts by mass to 42.3 parts by mass.

[0415] Next, 8.7 parts by mass of the obtained dye dispersion liquid, 25.9 parts by mass of the obtained color developer dispersion liquid, 31.2 parts by mass of an itaconic acid-modified polyvinyl alcohol aqueous solution (product name: KURARAY POVAL 25-88KL, solid content: 10% by mass, available from KURARAY CO., LTD.), 5 parts by mass of a polyamide epichlorohydrin resin aqueous solution (product name: WS-525, solid content: 25% by mass, available from SEIKO PMC CORPORATION), and 29.3 parts by mass of ion exchange water were admixed and stirred, thereby preparing a thermosensitive recording layer-forming liquid.

[0416] Next, a thermosensitive recording medium 15 was produced in the same manner as in Example 1, except that a thermosensitive recording layer was formed by using the above-prepared thermosensitive recording layer-forming liquid.

[0417] (Comparative Example 6)

[0418] A dye dispersion liquid and a color developer dispersion liquid were prepared in the same manner as in Example 1, except that in the preparation of the dye dispersion liquid and the color developer dispersion liquid, 10 parts by mass of the carboxyl group-containing acrylic resin aqueous solution (styrene-acrylic resin, product name: HPD-196, solid content: 36% by mass, available from BASF SE) was replaced with 7.2 parts by mass of a polyurethane resin aqueous solution (product name: Gen 0851, solid content: 50% by mass, available from Borchers Inc.), and the amount of ion exchange water was changed from 50.4 parts by mass to 53.2 parts by mass.

[0419] Next, 14.7 parts by mass of the obtained dye dispersion liquid, 44.1 parts by mass of the obtained color developer dispersion liquid, 15.1 parts by mass of a polyurethane resin dispersion liquid (product name: WLS-201, solid content: 35% by mass, available from DIC Corporation), and 26 parts by mass of ion exchange water were admixed and stirred, thereby preparing a thermosensitive recording layer forming liquid.

[0420] Next, the thermosensitive recording medium 16 was produced in the same manner as in Example 1, except that the thermosensitive recording layer was formed by using the above-prepared thermosensitive recording layer forming liquid.

[0421] Next, the thermosensitive recording media produced in Examples 1 to 10 and Comparative Examples 1 to 6 were subjected to evaluation of “hot water resistance (60°C),” “hot water resistance (40°C),” “water resistance,” “ethanol resistance,” “temperature and humidity resistance,” “humidity rubbing resistance,” “heat resistance (110°C),” “heat resistance (90°C),” and “LD laser printing suitability.”

[0422] The results of “hot water resistance (60°C),” “hot water resistance (40°C),” “water resistance,” “ethanol resistance,” “temperature and humidity resistance,” “humidity rubbing resistance,” “heat resistance (110°C),” and “heat resistance (90°C)” are presented in Tables 1 and 2.

[0423] <Hot water resistance (60°C)>

[0424] Each thermosensitive recording medium was provided to be printed using a CO2 laser marking machine (device name: LP-435TU, available from Panasonic Industrial Devices SUNX Co., Ltd.) under the following printing conditions, thereby producing a pre-test image sample.

[0425] The produced pre-test image sample was immersed in tap water at 60°C, and the water temperature was maintained at 60°C using a constant-temperature bath, and the sample was stored for 96 hours. The image density of the sample before and after storage for 96 hours was measured by a reflection densitometer (X-Rite eXact, available from X-Rite Inc.). The image survival rate was determined according to the following formula, and the results were evaluated based on the following criteria.

[0426] Image survival rate (%) = [(image density after test) / (image density before test)] x 100

[0427] (Printing conditions)

[0428] Working distance: 275 mm

[0429] Scanning speed: 900 mm / s

[0430] Laser wavelength: 10.6 microns

[0431] Laser power: 10%

[0432] (Evaluation Criteria)

[0433] A: Image survivability is 90% or more.

[0434] B: Image survivability is 80% or more but 89% or less.

[0435] C: Image survivability is 79% or less.

[0436] <Hot Water Resistance (40°C)>

[0437] Each produced test-before image sample was immersed in 40°C tap water, and the water temperature was maintained at 40°C using a constant temperature bath, and the sample was stored for 96 hours. The image density of the sample was measured before and after 96 hours of storage by a reflectance densitometer (X-Rite eXact, available from X-Rite Inc.). The image survivability was determined according to the following formula, and the results were evaluated based on the following criteria.

[0438] Image survivability (%) = [(image density after test) / (image density before test)] x 100

[0439] (Evaluation Criteria)

[0440] A: Image survivability is 90% or more.

[0441] B: Image survivability is 80% or more but 89% or less.

[0442] C: Image survivability is 79% or less.

[0443] <Water Resistance>

[0444] Each produced image sample was immersed in 23°C tap water for 96 hours. The image density of the sample was measured before and after 96 hours of immersion in water by a reflectance densitometer (X-Rite eXact, available from X-Rite Inc.). The image survivability was determined according to the following formula, and the results were evaluated based on the following criteria.

[0445] Image survivability (%) = [(image density after test) / (image density before test)] x 100

[0446] (Evaluation Criteria)

[0447] A: Image survivability is 90% or more.

[0448] B: Image survivability is 80% or more but 89% or less.

[0449] C: Image survivability is 79% or less.

[0450] <Ethanol resistance>

[0451] Each produced image sample was immersed in an 80% by mass aqueous ethanol solution for 30 seconds. The image density of the sample before and after immersion in the aqueous solution for 30 seconds was measured by a reflection densitometer (X-Rite eXact, available from X-Rite Inc.). The image survivability was determined according to the following formula, and the results were evaluated based on the following criteria.

[0452] Image survivability (%) = [(image density after test) / (image density before test)] x 100

[0453] (Evaluation criteria)

[0454] A: Image survivability is 90% or more.

[0455] B: Image survivability is 80% or more but 89% or less.

[0456] C: Image survivability is 79% or less.

[0457] <Temperature resistance and humidity resistance>

[0458] Each produced image sample was stored in an environment of 40°C and 90% RH for 72 hours. The image density of the sample before and after storage was measured by a reflection densitometer (X-Rite eXact, available from X-Rite Inc.). The image survivability was determined according to the following formula, and the results were evaluated based on the following criteria.

[0459] Image survivability (%) = [(image density after test) / (image density before test)] x 100

[0460] (Evaluation criteria)

[0461] A: Image survivability is 90% or more.

[0462] B: Image survivability is 80% or more but 89% or less.

[0463] C: Image survivability is 79% or less.

[0464] <Humidity abrasion resistance>

[0465] A drop of water was dropped on each produced image sample. After rubbing with a finger 100 times, whether or not peeling, dissolving, and blurring of each layer appeared was visually observed, and the results were evaluated based on the following criteria.

[0466] (Evaluation Criteria)

[0467] I: No peeling, dissolving, and blurring.

[0468] II: Peeling, dissolving, or blurring.

[0469] <Heat Resistance>

[0470] Each of the produced image samples was stored in an environment of 110°C and in an environment of 90°C for 1 hour. After the storage, the density of the background of the sample was measured by a reflection densitometer (X-Rite eXact, available from X-Rite Inc.). The results were evaluated based on the following criteria.

[0471] (Evaluation Criteria)

[0472] I: The background density was 0.29 or less.

[0473] II: The background density was 0.30 or more.

[0474] <LD Laser Printing Fitness>

[0475] Each of the heat-sensitive recording media produced in Examples 1 to 10 and Comparative Examples 1 to 6 was provided to be printed under the following printing conditions using an LD laser marker (Device name: Ricoh Rewritable Laser Marker LDM200, available from Ricoh Company Limited), thereby producing an image sample.

[0476] (Printing Conditions)

[0477] Working distance: 150 mm

[0478] Scanning speed: 3,000 mm / s

[0479] Laser wavelength: 980 nm

[0480] Laser power: 70%

[0481] (Evaluation Criteria)

[0482] I: Printable

[0483] II: Not printable

[0484] (Evaluation Results)

[0485] The heat-sensitive recording medium of Example 9, in which a photothermal conversion material is included in the heat-sensitive recording layer, was printable (I), but the heat-sensitive recording media of Examples 1 to 8 and 10 and Comparative Examples 1 to 6, in which a photothermal conversion material was not included in the heat-sensitive recording layer, were not printable (II).

[0486] [Table 1]

[0487]

[0488] [Table 2]

[0489]

[0490] For example, embodiments of the present disclosure are as follows.

[0491] <1> A heat-sensitive recording medium comprising:

[0492] a support; and

[0493] a heat-sensitive recording layer disposed on or over the support,

[0494] wherein the heat-sensitive recording layer includes a compound represented by general formula (1) and a styrene-acrylic acid resin,

[0495] [Chemical Formula 15]

[0496]

[0497] wherein, in general formula (1), R2is a C1-12linear, branched, or alicyclic alkyl group, a C7-12aralkyl group substituted with a C1-12alkyl group, a C1-12alkoxy group, a C6-12aryl group, or a halogen atom, or a C6-12aryl group which is unsubstituted or substituted with a C1-12alkyl group, a C1-12alkoxy group, a C6-12aryl group, or a halogen atom, wherein two or more R2may be the same as or different from each other; and A1is a hydrogen atom or a C1-4alkyl group, wherein two or more A1may be the same as or different from each other.

[0498] <2> The heat-sensitive recording medium according to <1>,

[0499] wherein the compound represented by general formula (1) is a compound represented by general formula (2),

[0500] [Chemical Formula 16]

[0501]

[0502] wherein, in General Formula (2), R2is a C1-12linear, branched, or alicyclic alkyl group, a C7-12aralkyl group which is unsubstituted or substituted with a C1-12alkyl group, a C1-12alkoxy group, a C6-12aryl group, or a halogen atom, or a C6-12aryl group which is unsubstituted or substituted with a C1-12alkyl group, a C1-12alkoxy group, a C6-12aryl group, or a halogen atom, and two or more R2may be the same as or different from each other.

[0503] <3> The heat-sensitive recording medium according to <2>,

[0504] wherein the compound represented by General Formula (2) is a compound represented by General Formula (3),

[0505] [Chemical Formula 17]

[0506]

[0507] wherein, in General Formula (3), R is an alkyl group; and n is an integer of 0 to 3.

[0508] <4> The heat-sensitive recording medium according to any one of <1> to <3>,

[0509] wherein the heat-sensitive recording layer further comprises a light-to-heat conversion material.

[0510] <5> The heat-sensitive recording medium according to any one of <1> to <4>,

[0511] wherein the support is a plastic film.

[0512] <6> The heat-sensitive recording medium according to any one of <1> to <5>,

[0513] wherein the support is a transparent film.

[0514] <7> The heat-sensitive recording medium according to any one of <1> to <6>, further comprising

[0515] a protective layer disposed on or over the heat-sensitive recording layer.

[0516] <8> The heat-sensitive recording medium according to any one of <1> to <6>, further comprising

[0517] a print layer disposed between the support and the heat-sensitive recording layer, or on a surface of the support opposite to a surface of the support on which the heat-sensitive recording layer is disposed, or on or over the support and the heat-sensitive recording layer.

[0518] <9> A heat-sensitive recording layer forming liquid, comprising:

[0519] a compound represented by General Formula (1);

[0520] Styrene-acrylic resin, and

[0521] solvent,

[0522] [Chemical Formula 18]

[0523]

[0524] In general formula (1), R2 is a C1-12 straight-chain, branched, or alicyclic alkyl group, a C7-12 aralkyl group substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom, or a C6-12 aryl group that is unsubstituted or substituted with a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom, wherein two or more R2s may be the same as or different from each other; and A1 is a hydrogen atom or a C1-4 alkyl group, wherein two or more A1s may be the same as or different from each other.

[0525] <10> according to <9> The thermal recording layer forming liquid,

[0526] The compound represented by general formula (1) is a compound represented by general formula (2).

[0527] [Chemical Formula 19]

[0528]

[0529] In general formula (2), R2 is a C1-12 straight-chain, branched, or alicyclic alkyl group, a C7-12 aralkyl group that is not substituted or is substituted by a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom, or a C6-12 aryl group that is not substituted or is substituted by a C1-12 alkyl group, a C1-12 alkoxy group, a C6-12 aryl group, or a halogen atom, wherein two or more R2s may be the same as or different from each other.

[0530] <11> according to <10> The thermal recording layer forming liquid,

[0531] The compound represented by general formula (2) is a compound represented by general formula (3).

[0532] [Chemical Formula 20]

[0533]

[0534] In general formula (3), R is an alkyl group; and n is an integer from 0 to 3.

[0535] <12> A method for producing a thermal recording medium, the method comprising:

[0536] The heat-sensitive recording layer forming liquid according to any one of <9> to <11> is applied to a support to form a heat-sensitive recording layer.

[0537] <13> An image recording method comprising

[0538] irradiating the heat-sensitive recording medium according to any one of <1> to <8> with a laser to record an image.

[0539] <14> An image recording method comprising

[0540] heating the heat-sensitive recording medium according to any one of claims 1 to 8 with a thermal head to record an image.

[0541] The heat-sensitive recording medium according to any one of <1> to <8>, the heat-sensitive recording layer forming liquid according to any one of <9> to <11>, the method of producing a heat-sensitive recording medium according to <12>, and the image recording method according to <13> to <14> are capable of solving the various problems existing in the art described above, and capable of achieving the objects of the present disclosure.

[0542] List of Reference Numerals

[0543] 1: Support

[0544] 2: Heat-sensitive recording layer

[0545] 3: Protective layer

[0546] 4: Printed layer

Claims

1. A thermal recording medium, comprising: carrier; and A thermal recording layer disposed on or above the carrier. The thermal recording layer comprises a compound represented by general formula (1) and a styrene-acrylic resin. [Chemical Formula 1] In general formula (1), R2 is one of the following conditions (1) to (3): (1): C1-12 straight-chain, branched, or alicyclic alkyl groups, (2): C7-12 aryl groups that are unsubstituted or substituted with C1-12 alkyl, C1-12 alkoxy, C6-12 aryl, or halogen atoms, and (3): C6-12 aryl groups that are unsubstituted or substituted with C1-12 alkyl, C1-12 alkoxy, C6-12 aryl, or halogen atoms; and Two or more of these R2 values ​​can be the same as or different from each other; and A1 is a hydrogen atom or a C1-4 alkyl group, wherein two or more A1 atoms may be the same as or different from each other.

2. The thermal recording medium according to claim 1, The compound represented by general formula (1) is a compound represented by general formula (2). [Chemical Formula 2] in, In general formula (2), R2 is one of the following conditions (1) to (3): (1): C1-12 straight-chain, branched, or alicyclic alkyl groups, (2): C7-12 aryl groups that are unsubstituted or substituted with C1-12 alkyl, C1-12 alkoxy, C6-12 aryl, or halogen atoms, and (3): C6-12 aryl groups that are unsubstituted or substituted with C1-12 alkyl, C1-12 alkoxy, C6-12 aryl, or halogen atoms; and Two or more of these R2 values ​​can be the same as or different from each other.

3. The thermal recording medium according to claim 2, The compound represented by general formula (2) is a compound represented by general formula (3). [Chemical Formula 3] in, In general formula (3), R is an alkyl group; and n is an integer from 0 to 3.

4. The thermal recording medium according to any one of claims 1 to 3, The thermal recording layer further includes a photothermal conversion material.

5. The thermal recording medium according to any one of claims 1 to 4, The carrier is a plastic film.

6. The thermal recording medium according to any one of claims 1 to 5, The carrier is a transparent film.

7. The thermal recording medium according to any one of claims 1 to 6, further comprising: A protective layer disposed on or above the thermal recording layer.

8. The thermal recording medium according to any one of claims 1 to 6, further comprising: A printing layer is disposed between the carrier and the thermal recording layer, or on the carrier surface opposite to the carrier surface on which the thermal recording layer is disposed, or on or above the carrier and the thermal recording layer.

9. A thermal recording layer forming solution, comprising: Compounds represented by general formula (1); Styrene-acrylic resin, and Solvent, [Chemical Formula 4] In general formula (1), R2 is one of the following conditions (1) to (3): (1): C1-12 straight-chain, branched, or alicyclic alkyl groups, (2): C7-12 aryl groups that are unsubstituted or substituted with C1-12 alkyl, C1-12 alkoxy, C6-12 aryl, or halogen atoms, and (3): C6-12 aryl groups that are unsubstituted or substituted with C1-12 alkyl, C1-12 alkoxy, C6-12 aryl, or halogen atoms; and Two or more of these R2 values ​​can be the same as or different from each other; and A1 is a hydrogen atom or a C1-4 alkyl group, wherein two or more A1 atoms may be the same as or different from each other.

10. The thermal recording layer forming solution according to claim 9, The compound represented by general formula (1) is a compound represented by general formula (2). [Chemical Formula 5] in, In general formula (2), R2 is one of the following conditions (1) to (3): (1): C1-12 straight-chain, branched, or alicyclic alkyl groups, (2): C7-12 aryl groups that are unsubstituted or substituted with C1-12 alkyl, C1-12 alkoxy, C6-12 aryl, or halogen atoms, and (3): C6-12 aryl groups that are unsubstituted or substituted with C1-12 alkyl, C1-12 alkoxy, C6-12 aryl, or halogen atoms; and Two or more of these R2 values ​​can be the same as or different from each other.

11. The thermal recording layer forming solution according to claim 10, The compound represented by general formula (2) is a compound represented by general formula (3). [Chemical Formula 6] in, In general formula (3), R is an alkyl group; and n is an integer from 0 to 3.

12. A method for producing a thermal recording medium, the method comprising: The thermal recording layer forming liquid according to any one of claims 9 to 11 is applied to the carrier to form a thermal recording layer.

13. An image recording method, comprising: An image is recorded by irradiating a thermal recording medium according to any one of claims 1 to 8 with a laser.

14. An image recording method, comprising: A thermal recording medium according to any one of claims 1 to 8 is heated by a thermal head to record an image.

Images