JP7286054B1 - Thermal recording composition - Google Patents

Abstract

Provided is a thermal recording material which is improved in thermal responsiveness and storage stability of the printed part and background compared to conventional thermal recording materials containing a non-phenolic compound as a color developer. [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate, N-[2 -(3-phenylureido)phenyl]benzenesulfonamide, or N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea with diphenylsulfone or 1,2 as a sensitizer - A thermal recording composition containing bis(3-methylphenoxy)ethane and 1,3-diphenylurea as a stabilizer.

Description

The present invention is a heat-sensitive recording composition comprising a color former, a developer containing a specific color-developing compound, a stabilizer (storage-improving agent) containing a specific compound, and a sensitizer containing a specific compound. and a heat-sensitive recording material having a heat-sensitive recording layer comprising the composition on a support.

A heat-sensitive recording material is generally prepared by dispersing a color-forming compound and a color-developing compound in fine particles in a dispersing medium and then mixing the two. Additives are added to prepare a coating solution, and this coating solution is applied to paper, film, synthetic paper, or the like. When the obtained heat-sensitive recording material is heated using a thermal printer or the like with a built-in thermal head, one or both of the color-developing compound and the color-developing compound are melted, and a chemical reaction occurs when the two come into contact with each other to develop color. A printed portion is obtained.
Compared to other recording methods, the thermal recording method has the following advantages: (1) no noise during recording, (2) no need for development and fixing, (3) maintenance-free, and (4) relatively inexpensive machines. It is widely used in the field of facsimiles, computer output, printers such as calculators, recorders for medical measurement, automatic ticket vending machines, thermal recording labels, etc.

In recent years, the use of thermal recording materials has increased in the fields of labels, train tickets, coupons, etc. associated with the POS systemization of retail stores, supermarkets, etc. and the automation systemization of transportation facilities. In these applications, resistance of the printed portion to water, heat, oil, plasticizer, alcohol, hand cream, etc., and storage stability of the unprinted portion (background) before color development are required. In addition, the demand for high-speed recording is increasing, and there is a strong demand for the development of a heat-sensitive recording material that satisfies this demand and has excellent thermal responsiveness. In order to improve the thermal responsiveness, a color-developing compound with a low melting point and a small heat of fusion is generally required. A phenomenon called background fogging, in which the non-printed portion (background) of the thermosensitive recording material darkens, tends to occur. Therefore, there is a demand for a heat-sensitive recording material that has improved thermal responsiveness and improved texture stability.

In general, color-developing compounds having a phenolic hydroxyl group have high color-developing ability. Among them, many reports have been made on bisphenol-based compounds due to their high color-developing density. Bisphenol A) (Patent Document 1) and 4,4′-dihydroxydiphenylsulfone (Bisphenol S) (Patent Document 2) have been proposed. However, since these compounds have a high melting point, they are inferior in thermal responsiveness and also have the drawback that the printed portion is inferior in water resistance. In addition, the use of phenolic compounds such as bisphenol A is regarded as a problem due to endocrine problems. Therefore, there is a need for non-phenolic color-developing compounds that do not contain phenolic structures.

In response to such demands, [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate (Patent Document 3), N-[2-(3-phenyl A thermal recording material has been proposed comprising ureido)phenyl]benzenesulfonamide (Patent Document 4) and N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea (Patent Document 5). ing. A heat-sensitive recording material containing [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate and 1,3-diphenylurea as a storage stability improver has also been proposed (Patent Document 6).

A heat-sensitive recording material containing [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate or N-[2-(3-phenylureido)phenyl]benzenesulfonamide as a developing compound has excellent heat resistance. It is excellent, and it is difficult for the background to fog, and the stability of the background is very good. However, these thermosensitive recording materials are unsatisfactory in terms of thermal responsiveness and storage stability of the printed area. In particular, there is a demand for improved resistance of the printed area to oil, hand cream, alcohol, and plasticizers. .
In addition, the heat-sensitive recording material containing [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate and 1,3-diphenylurea as a storage stability improver has excellent oil resistance and hand cream resistance in the printed area. , alcohol resistance, and plasticizer resistance are not always satisfactory. Therefore, there is a demand for further improvement in these performances.

In addition, a heat-sensitive recording material containing N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea is not necessarily sufficient in terms of hand cream resistance of the printed area and stability of the background. Further improvement of these performances is desired.

U.S. Pat. No. 3,539,375 JP-A-57-11088 Patent No. 6529197 WO2014/080615 Patent No. 4601174 JP 2019-130879 A JP 2006-247611 A

The present invention aims to improve the problems of conventional thermal recording materials containing non-phenolic compounds as color developers, more specifically, thermally responsive recording materials containing non-phenolic compounds as color developers. , and to provide a heat-sensitive recording material with improved storage stability of the printed portion and background.

As a result of intensive studies, the present inventors have found that 1,3-diphenylurea as a stabilizer (preservability improver) in a heat-sensitive recording composition containing a specific non-phenolic color-developing compound together with a color former. The present inventors have newly found that the above problems can be solved by incorporating diphenylsulfone or 1,2-bis(3-methylphenoxy)ethane as a sensitizer, and have completed the present invention.

That is, the present invention
[1] A thermal recording composition containing a color former, a developer, a sensitizer and a stabilizer, wherein the developer is [3-(3-phenylureido)phenyl]=4-methylbenzene sulfonate, N-[2-(3-phenylureido)phenyl]benzenesulfonamide, or N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea, said sensitizing a thermal recording composition containing diphenylsulfone or 1,2-bis(3-methylphenoxy)ethane as the agent and 1,3-diphenylurea as the stabilizing agent;
[2] The thermal recording composition according to [1], wherein the coloring agent contains at least one compound selected from the group consisting of triarylmethane compounds, fluoran compounds, azaphthalide compounds and fluorene compounds.
[3] As the color former, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N-ethyl-p-toluidino)-6-methyl-7-anilinofluorane, 3-(N -ethyl-N-isoamylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-(o,p-dimethylanilino)fluorane, 3-pyrrolidino-6-methyl-7 -anilinofluorane, 3-(cyclohexyl-N-methylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-7-(m-trifluoromethylanilino)fluorane, 3-Nn -dibutylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-(m-methylanilino)fluorane, 3-Nn-dibutylamino-7-(o-chloroanilino)fluorane, 3-(N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-ethoxypropylamino)-6-methyl-7-anilinofluorane , 3-(N-ethyl-N-isobutylamino)-6-methyl-7-anilinofluorane and 3-dipentylamino-6-methyl-7-anilinofluorane at least one selected from the group consisting of The thermal recording composition according to [2], which contains the fluoran compound of
[4] The content of the color developer is 1:1 to 5:1 in mass ratio (color developer: color former) to the content of the color former, [1] to [3] ] The thermal recording composition according to any one of
[5] The content of the 1,3-diphenylurea is 1:10 to 2.5:1 in mass ratio (1,3-diphenylurea:developer) to the content of the developer. The thermal recording composition according to any one of [1] to [4],
[6] The content of the sensitizer is 1:5 to 3:1 in mass ratio (sensitizer:developer) to the content of the developer. The thermal recording composition according to any one of [5],
[7] A heat-sensitive recording material having, on a support, a heat-sensitive recording layer comprising the heat-sensitive recording composition according to any one of [1] to [6] above,
[8] The heat-sensitive recording material of [7], wherein the support is fine paper, synthetic paper or plastic film;
[9] The heat-sensitive recording material according to [7] or [8], wherein the heat-sensitive recording layer has a mass per unit area of 1 to 20 g/m ² .
[10] The heat-sensitive recording material according to any one of [7] to [9], further comprising an undercoat layer containing an organic pigment and/or an inorganic pigment between the support and the heat-sensitive recording layer.
[11] The thermal recording material of [10], wherein the inorganic pigment is an oil-absorbing inorganic pigment having an oil absorption of 70 to 150 ml/100 g.
[12] The thermal recording material according to [11], wherein the inorganic pigment is calcined kaolin, and [13] The organic pigment is plastic hollow particles having an average inner diameter/average outer diameter of 0.50 to 0.99. The thermal recording material according to [10],
Regarding.

The heat-sensitive recording material according to the present invention contains [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate or N-[2-(3-phenylureido)phenyl]benzenesulfonamide as a color-developing compound. It has improved properties in terms of thermal response, oil resistance, hand cream resistance, alcohol resistance, and plasticizer resistance of the printed area, compared to conventional thermosensitive recording materials.
In addition, the heat-sensitive recording material according to the present invention is different from conventional heat-sensitive recording materials containing [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate and 1,3-diphenylurea as a storage-improving agent. However, it has improved properties in terms of oil resistance, hand cream resistance, alcohol resistance, and plasticizer resistance of the printed area.
Furthermore, the heat-sensitive recording material according to the present invention is resistant to hand cream in the printed area, compared to conventional heat-sensitive recording materials containing N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea. It has improved properties in terms of durability and storage stability of the skin.

Although the present invention will be described in detail below based on embodiments, the present invention is not limited to these embodiments.

Thermal Recording Composition The thermal recording composition of the present invention comprises a color former, a developer containing a specific color-developing compound, a sensitizer containing a specific compound, and a stabilizer containing a specific compound. (storage improver).
In the heat-sensitive recording composition of the present invention, the coloring agent is not particularly limited as long as it is a coloring compound generally used for pressure-sensitive recording paper or heat-sensitive recording paper.
Specific examples of color formers (color-forming compounds) include fluorane compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds, fluorene compounds and vinylphthalide compounds, and triarylmethane compounds and fluoran compounds. , an azaphthalide compound or a fluorene compound, and more preferably a fluorane compound. These color-developing compounds can be used alone or in combination.

The fluoran compound is a compound having a fluoran skeleton, and in the present invention, it may be any fluoran compound that is generally used as a coloring agent for thermal recording paper, and is not particularly limited.
Specific examples of fluoran compounds include 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-(N-methyl-N-cyclohexylamino )-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-isobutylamino) -6-methyl-7-anilinofluorane, 3-[N-ethyl-N-(3-ethoxypropyl)amino]-6-methyl-7-anilinofluorane, 3-(N-ethyl-N- hexylamino)-6-methyl-7-anilinofluorane, 3-dipentylamino-6-methyl-7-anilinofluorane, 3-(N-methyl-N-propylamino)-6-methyl-7- Anilinofluorane, 3-(N-ethyl-N-tetrahydrofurylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-(p-chloroanilino)fluorane, 3-diethylamino -6-methyl-7-(p-fluoroanilino)fluorane, 3-[N-ethyl-N-(p-tolyl)amino]-6-methyl-7-anilinofluorane, 3-diethylamino-6- methyl-7-(p-toluidino)fluorane, 3-diethylamino-7-(o-chloroanilino)fluorane, 3-dibutylamino-7-(o-chloroanilino)fluorane, 3-diethylamino-7-(o-fluoroanilino ) fluoran, 3-dibutylamino-7-(o-fluoroanilino)fluorane, 3-diethylamino-7-(3,4-dichloroanilino)fluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane , 3-diethylamino-6-chloro-7-ethoxyethylaminofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane Olan, 3-diethylamino-7-octylfluorane, 3-[N-ethyl-N-(p-tolyl)amino]-6-methyl-7-phenethylfluorane, 2-methyl-6-(Np- tolyl-N-ethylamino)fluorane (RED520), 9-(N-ethyl-N-isopentylamino)spiro[benzo[a]xanthene-12,3′-phthalide] (RED500), 2′-anilino-6 '-(N-ethyl-N-isopentylamino)-3'-methylspiro[phthalido-3,9'-xanthene] (S-205), 2'-anilino-6'-(N,N-dipentane-1 -ylamino)-3′-methyl-3H-spiro[isobenzofuran-1,9′-xanthene]-3-one (Black305), 2′-anilino-6′-(dibutylamino)-3′-methylspiro[phthalide -3,9′-xanthene] (Black400), 2′-anilino-6′-[N-ethyl-N-(4-tolyl)amino]-3′-methyl-3H-spiro[isobenzofuran-1,9 '-xanthene]-3-one (ETAC), 6-(diethylamino)-2-[(3-trifluoromethyl)anilino]xanthene-9-spiro-3'-phthalide (Black100), 1-ethyl-8- [N-ethyl-N-(4-methylphenyl)amino]-2,2,4-trimethyl-1,2-dihydrospiro[11H-chromeno[2,3-g]quinoline-11,3′-phthalide] (H-1046), 3-dibutylamino-6-methyl-7-bromofluorane and 3-[4-(diethylamino)phenyl]-3-(1-ethyl-2-methyl-1H-indol-3-yl )-1(3H)-isobenzofuranone (Blue 502), and 3-dibutylamino-6-methyl-7-anilinofluorane is preferred.

The triarylmethane compound is a compound having a triarylmethane skeleton, and is not particularly limited as long as it is a triarylmethane compound generally used as a coloring agent for thermal recording paper.
Specific examples of triarylmethane compounds include 3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone or CVL), 3,3-bis(p-dimethylaminophenyl ) phthalide, 3-(p-dimethylaminophenyl)-3-(1,2-dimethylaminoindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindole-3- yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-phenylindol-3-yl)phthalide, 3,3-bis(1,2-dimethylindol-3-yl)-5-dimethylamino phthalide, 3,3-bis(1,2-dimethylindol-3-yl)-6-dimethylaminophthalide, 3,3-bis(9-ethylcarbazol-3-yl)-5-dimethylaminophthalide , 3,3-(2-phenylindol-3-yl)-5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3-(1-methylpyrrol-2-yl)-6-dimethylaminophthalide , 3-(4-diethylamino-2-methylphenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide (Blue 200), 3-[4-(diethylamino)-2-hexyl Oxyphenyl]-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide (Blue203), 3-(4-diethylamino-2-methylphenyl)-3-(1-ethyl 2-methyl -1H-indol-3-yl)-4-azaphthalide (Blue 220) and 7-(4-diethylamino-2-ethoxyphenyl)-7-(1-ethyl-2-methyl-1H-indol-3-yl)furo [3,4-b]pyridin-5(7H)-one (Blue63) and the like.

The spiro compound is a compound having a spiro skeleton. In the present invention, the spiro compound is not particularly limited as long as it is generally used as a coloring agent for thermal recording paper.
Specific examples of spiro compounds include 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-propylspirobenzopyran, 3-methylnaphtho-(3-methoxybenzo)spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro(indoline-2,2'-benzopyran) and the like.

The diphenylmethane compound is a compound having a diphenylmethane skeleton, and in the present invention, it may be any diphenylmethane compound that is generally used as a coloring agent for thermal recording paper, and is not particularly limited.
Specific examples of diphenylmethane compounds include N-halophenyl-leucoauramine, 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether and N-2,4,5-trichlorophenylleucoauramine.

The thiazine compound is a compound having a thiazine skeleton, and in the present invention, it may be a thiazine compound generally used as a color former for thermal recording paper, and is not particularly limited.
Specific examples of thiazine compounds include benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue.

The lactam compound is a compound having a lactam skeleton, and in the present invention, it may be any lactam compound that is generally used as a color former for thermal recording paper, and is not particularly limited.
Specific examples of lactam compounds include rhodamine B anilinolactam and rhodamine Bp-chloroanilinolactam.

The fluorene compound is a compound having a fluorene skeleton, and in the present invention, it may be any fluorene compound that is generally used as a coloring agent for thermal recording paper, and is not particularly limited.
Specific examples of fluorene compounds include 3,6-bis(dimethylamino)fluorenespiro(9,3')-6'-dimethylaminophthalide, 3,6-bis(dimethylamino)fluorenespiro(9,3' )-6′-pyrrolidinophthalide and 3-dimethylamino-6-diethylaminofluorene spiro(9,3′)-6′-pyrrolidinophthalide.

The vinyl phthalide compound is a compound having a vinyl phthalide skeleton, and in the present invention, any vinyl phthalide compound generally used as a coloring agent for thermal recording paper can be used without particular limitation.
Specific examples of vinylphthalide compounds include 3-[2,2-bis(4-diethylaminophenyl)vinyl]-6-dimethylaminophthalide (H-3035) and 3,3-bis[2-(4-dimethylamino phenyl)-2-(4-methoxyphenyl)vinyl]-4,5,6,7-tetrachlorophthalide (NIR Black78) and the like.

The heat-sensitive recording composition of the present invention comprises [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate, N-[2-(3-phenylureido)phenyl]benzenesulfone, and the above-described color former. amide, or N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea as a developer, 1,3-diphenylurea as a stabilizer, diphenylsulfone or 1 , 2-bis(3-methylphenoxy)ethane as a sensitizer.
Due to such a specific combination, the thermosensitive recording composition according to the present invention is superior to conventional thermosensitive recording materials containing non-phenolic color-developing compounds in terms of both thermal responsiveness and stability of the printed area and background. It is possible to provide a heat-sensitive recording material that is improved in one of these respects.

In one embodiment of the present invention, the thermal recording composition contains [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate, N-[ Developers other than 2-(3-phenylureido)phenyl]benzenesulfonamide and N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea may also be included. Such a developer is not particularly limited. saccharin derivatives, sulfonamide derivatives, malonamide derivatives, thiourea derivatives, sulfonylurea derivatives, aromatic carboxylic acid derivatives and the like.

Specific examples of benzotriazole derivatives include benzotriazole, 5-methyl-1H-benzotriazole, 4-methyl-1H-benzotriazole, phenyl-6benzotriazole, phenyl-5benzotriazole, chloro-5benzotriazole, chloro- 5-methylbenzotriazole, chloro-5-isopropyl-7-methyl-4-benzotriazole, bromo-5-benzotriazole and the like.

Specific examples of saccharin derivatives include saccharin, 1-bromosaccharin, 1-nitrosaccharin and 1-aminosaccharin.

Specific examples of sulfonamide derivatives include methanylanilide, N-phenyl-4-aminobenzenesulfonamide, neourilone, N-phenyl-3-nitrobenzenesulfonamide, N-(4-methyl-2-nitrophenyl)benzenesulfonamide, N-(2-methoxyphenyl)-p-toluenesulfonamide, N-(4-thoxyphenyl)-p-toluenesulfonamide, N-(2-chlorophenyl)-p-toluenesulfonamide, N-(4-methyl Phenyl)-4-methylbenzenesulfonamide, N-(2-methylphenyl)-p-toluenesulfonamide, N-phenylbenzenesulfonamide, 4-bromo-4'-methylbenzenesulfonanilide, N-(4-bromo phenyl)benzenesulfonamide, N-(3-nitrophenyl)benzenesulfonamide, N-(4-nitrophenyl)-4-methylbenzenesulfonamide, N-(4-methylphenyl)benzenesulfonamide, N-phenyl- Examples include p-toluenesulfonamide and N-phenylbenzenesulfonamide.

Specific examples of malonamide derivatives include N,N'-bis(2-hydroxy-5-phenyl)phenyl-malonamide, N,N'-diphenylmalonamide, N,N'-bis(2,4,6-tri Bromophenyl)malonamide, N,N'-bis(2-aminophenyl)malonamide, N,N'-bis(m-trifluoromethylphenyl)malonamide, N,N'-bis(m-trifluoromethylphenyl)α , α-dichloromalonamide and diethylmalondianilide.

Specific examples of thiourea derivatives include 1,3-bis(4-methylphenyl)thiourea, 1,3-bisphenylthiourea, 1,3-bis(4-chlorophenyl)thiourea, 1,3-bis (4-Methoxyphenyl)thiourea, N,N'-bis(3-chlorophenyl)thiourea, 1,3-bis(3-methoxyphenyl)thiourea, 1,3-bis(3-methylphenyl)thiourea , 1,3-bis(4-benzylphenyl)thiourea, 1,3-bis(4-bromophenyl)thiourea, 1-phenyl-3-butylthiourea and 1-phenyl-3-ethylthiourea. .

Specific examples of sulfonylurea derivatives include N-(p-toluenesulfonyl)-N'-(3-n-butylaminosulfonylphenyl)urea, N-(p-toluenesulfonyl)-N'-(4-trimethylacetophenyl ) urea, N-(benzenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea, N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonylphenyl)urea, N- (p-toluenesulfonyl)-N'-(3-phenylsulfonyloxyphenyl)urea, tolbutamide, chlorpropamide and the like.

Specific examples of aromatic carboxylic acid derivatives include benzyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5- di-t-butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids or polyvalent metal salts thereof, and the like.

From the viewpoint of thermal responsiveness and storage stability of the background, the content of the developer in the thermosensitive recording composition is usually 1 in mass ratio (color developer:color former) to the content of the color former. : 10 to 10:1, preferably 1:2 to 7:1, more preferably 1:1 to 5:1, still more preferably 1.5:1 to 4:1, especially It is preferably 2:1 to 3:1.
[3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate, N-[2-(3-phenylureido)phenyl]benzenesulfonamide, and and N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea may be used in combination as a developer.

In addition, the content of 1,3-diphenylurea in the heat-sensitive recording composition is usually 1:20 to the content of the developer in terms of mass ratio (1,3-diphenylurea:developer). 8:1, preferably 7:100 to 5:1, more preferably 1:10 to 2.5:1, particularly preferably 1:2 to 1:1. By setting the content ratio of the color developer and 1,3-diphenyl urea within the above range, excellent characteristics can be exhibited in terms of printing density (thermal response) and resistance to plasticizers or oils in the printed area. be able to.

In addition, the content of diphenylsulfone or 1,2-bis(3-methylphenoxy)ethane in the heat-sensitive recording composition is a mass ratio (diphenylsulfone and/or 1,2- bis(3-methylphenoxy)ethane:color developer), usually 1:20 to 8:1, preferably 1:10 to 5:1, more preferably 1:5 to 3:1, Especially preferred is 2:1 to 1:1. By setting the content ratio of the color developer and diphenyl sulfone or 1,2-bis(3-methylphenoxy)ethane within the above range, the printing density (thermal response) and the plasticizer or oil content of the printed part can be improved. Excellent properties can be exhibited in terms of resistance.

The heat-sensitive recording composition may optionally contain a sensitizer other than diphenylsulfone and 1,2-bis(3-methylphenoxy)ethane and a stabilizer other than 1,3-diphenylurea (storability improver). , binders, fillers and other additives. In addition, when the heat-sensitive recording layer has a multilayer structure, these optional components may be contained in layers other than the layer comprising the heat-sensitive recording composition of the present invention. In the case of a heat-sensitive recording material having an undercoat layer or an overcoat layer provided above and/or below the heat-sensitive recording layer, it can be contained in these layers.

Specific examples of sensitizers (heat-fusible compounds) other than diphenylsulfone and 1,2-bis(3-methylphenoxy)ethane include waxes such as animal and plant waxes and synthetic waxes, higher fatty acids, and higher fatty acid amides. , higher fatty acid anilides, naphthalene derivatives, aromatic ethers, aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, carbonic acid or oxalic acid diester derivatives, biphenyl derivatives, terphenyl derivatives, sulfone derivatives, aromatic ketone derivatives and aromatic carbonization A hydrogen compound etc. are mentioned.

Specific examples of waxes include Japan wax, carnauba wax, shellac, paraffin, montan wax, paraffin oxide, polyethylene wax and polyethylene oxide, and specific examples of higher fatty acids include stearic acid and behenic acid. be done. Specific examples of higher fatty acid amides include stearamide, oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolbehenic acid amide, methylenebisstearic acid amide and ethylenebisstearic acid amide. Specific examples of fatty acid anilide include stearic acid anilide and linoleic acid anilide, and specific examples of naphthalene derivatives include 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-hydroxynaphthoic acid phenyl ester and 2, and 6-diisopropylnaphthalene. Specific examples of aromatic ethers include 1,2-diphenoxyethane, 1,4-diphenoxybutane, 1,2-bis(4-methylphenoxy)ethane, 1,2-bis(4-methoxyphenoxy)ethane , 1,2-bis(3,4-dimethylphenyl)ethane, 1-phenoxy-2-(4-chlorophenoxy)ethane, 1-phenoxy-2-(4-methoxyphenoxy)ethane, 1,2-diphenoxy Examples include methylbenzene and diphenyl glycol, and specific examples of aromatic carboxylic acid derivatives include benzyl p-hydroxybenzoate, benzyl p-benzyloxybenzoate, and dibenzyl terephthalate. Specific examples of aromatic sulfonate derivatives include phenyl p-toluenesulfonate, phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate and 4-tolylmesitylenesulfonate, and carbonic acid or oxalate diester derivatives. Specific examples include diphenyl carbonate, dibenzyl oxalate, di(4-chlorobenzyl) oxalate and di(4-methylbenzyl) oxalate. Specific examples of biphenyl derivatives include Examples include p-benzylbiphenyl and p-allyloxybiphenyl. Specific examples of the terphenyl derivative include m-terphenyl and the like, and specific examples of the sulfone derivative include p-toluenesulfonamide, benzenesulfonanilide, p-toluenesulfonanilide and the like. Specific examples of aromatic ketone derivatives include 4,4'-dimethylbenzophenone and dibenzoylmethane, and specific examples of aromatic hydrocarbon compounds include p-acetotoluidine.

Specific examples of stabilizers (storage improvers) other than 1,3-diphenylurea include 2,2′-methylenebis(4-methyl-6-t-butylphenol), 2,2′-methylenebis(4- ethyl-6-t-butylphenol), 2,2′-ethylidenebis(4,6-di-t-butylphenol), 4,4′-thiobis(2-methyl-6-t-butylphenol), 4,4′ -butylidenebis(6-t-butyl-m-cresol), 1-[α-methyl-α-(4'-hydroxyphenyl)ethyl]-4-[α',α'-bis(4'-hydroxyphenyl) ethyl]benzene, 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl) butane, tris(2,6-dimethyl-4-tert-butyl-3-hydroxybenzyl)isocyanurate, 4,4'-thiobis(3-methylphenol), 4,4'-dihydroxy-3,3',5 ,5′-tetrabromodiphenylsulfone, 4,4′-dihydroxy-3,3′,5,5′-tetramethyldiphenylsulfone, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, Hindered phenol compounds such as 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane and 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,4-diglycidyloxy Benzene, 4,4'-diglycidyloxydiphenylsulfone, 4-benzyloxy-4'-(2-methylglycidyloxy)diphenylsulfone, diglycidyl terephthalate, cresol novolak type epoxy resin, phenol novolac type epoxy resin, bisphenol A type epoxy compounds such as epoxy resins, N,N'-di-2-naphthyl-p-phenylenediamine, sodium or polyvalent metal salts of 2,2'-methylenebis(4,6-di-t-butylphenyl)phosphate, Bis(4-ethyleneiminocarbonylaminophenyl)methane, a ureaurethane compound (such as color-developing compound UU manufactured by Chemipro Kasei Co., Ltd.), and a diphenylsulfone crosslinked compound represented by the following formula (1) or a mixture thereof, etc. mentioned.

式（１）中のａは０乃至６の整数である。

a in Formula (1) is an integer of 0 to 6;

Specific examples of binders include
Cellulose derivatives such as methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose; polyvinyl alcohol (PVA), carboxy-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, silyl-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, acetoacetyl Polyvinyl alcohols with various degrees of saponification and polymerization such as modified polyvinyl alcohol; polyvinylpyrrolidone, polyacrylamide, sodium polyacrylate, starch and derivatives thereof (e.g., oxidized starch); sulfosuccinates such as sodium dioctyl sulfosuccinate; dodecyl Sodium benzenesulfonate, sodium salt of lauryl alcohol sulfate, fatty acid salt, casein, gelatin, water-soluble isoprene rubber, alkali salt of styrene/maleic anhydride copolymer, iso(or diiso)butylene/maleic anhydride copolymer Aqueous solutions or emulsions of water-soluble polymers such as alkali salts of; or (meth)acrylate copolymers, styrene/(meth)acrylate copolymers, polyurethanes, polyester-based polyurethanes, polyether-based polyurethanes, polyacetic acid Vinyl, ethylene/vinyl acetate copolymer, starch-vinyl acetate graft copolymer, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, polyvinylidene chloride, polystyrene, styrene/butadiene (SB) copolymer, carboxylation Styrene/butadiene (SB) copolymer, styrene/butadiene/acrylic acid copolymer, acrylonitrile/butadiene (NB) copolymer, carboxylated acrylonitrile/butadiene (NB) copolymer, colloidal silica and (meth)acrylic Emulsions of hydrophobic polymers such as composite particles of resins and the like can be mentioned.

Specific examples of fillers include:
Calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, kaolin, calcined kaolin, lithopone, talc, clay, magnesium hydroxide, aluminum hydroxide, titanium oxide, zinc oxide, aluminum oxide, barium sulfate, diatomaceous earth, clay oxide, Inorganic pigments such as bentonite, synthetic aluminum silicate, surface-treated calcium carbonate and silica; or organic pigments such as urea-formalin resin, styrene-methacrylic acid copolymer resin, polystyrene resin, and raw starch particles.

Other additives include, for example, higher fatty acid metal salts such as zinc stearate and calcium stearate, which are used together for the purpose of preventing wear and sticking of the thermal head; and used together for the purpose of imparting antioxidant or anti-aging effects. UV absorbers such as phenol derivatives, benzophenone compounds, benzotriazole compounds, various cross-linking agents, surfactants, antifoaming agents, and the like. These antioxidants or UV absorbers may be microencapsulated, if desired.

The content of optional components in the heat-sensitive recording composition is not particularly limited as long as it does not impair the effects of the present invention. (methylphenoxy)ethane and other optional sensitizers in a total amount of 80% by mass or less, and the stabilizer is 1,3-diphenylurea and an optional stabilizer other than 1,3-diphenylurea in a total amount of 30%. 90% by mass or less for binders, 80% by mass or less for fillers, and 30% by mass or less for other additives such as lubricants, surfactants, defoaming agents, and ultraviolet absorbers. is a tentative guideline (% by mass is the solid content conversion value of each component).

Heat-Sensitive Recording Material In one embodiment of the present invention, a heat-sensitive recording material comprises a support and a heat-sensitive recording layer formed of the above-described heat-sensitive recording composition provided on the support.
The material and shape of the support are not particularly limited. films and non-woven fabrics.
The method of providing the thermosensitive recording layer on the support is also not particularly limited. , Attritor, sand mill, or high-pressure jet mill, etc., to obtain a dispersion by pulverizing and dispersing, and mixing each obtained dispersion and, if necessary, other optional components to make a thermal recording composition. A thermal recording layer can be produced by obtaining a dispersion, coating it on a support, and drying it.
The amount of the dispersion liquid of the thermal recording composition to be applied is not particularly limited, but it is preferably an amount such that the mass per unit area of the thermal recording layer after drying is 1 to 20 g/m ² .

If necessary, an undercoat layer may be provided between the support and the heat-sensitive recording layer, and an overcoat layer may be provided on the heat-sensitive recording layer. For the undercoat layer and the overcoat layer, constituent components other than the color developer and color former of the thermal recording composition (for example, binders and other additives) are appropriately selected according to the purpose, A dispersion may be prepared by pulverizing and dispersing in the same manner as in the method for preparing a dispersion of a heat-sensitive recording composition, and the dispersion may be coated on a support or a prescribed layer and dried to form a film. The coating amount of the dispersion for the undercoat layer and overcoat layer is not particularly limited, but the amount is such that the mass per unit area of the undercoat layer and overcoat layer after drying is 0.1 to 10 g/m ² . is preferably applied.

The undercoat layer preferably contains at least one of an organic pigment and an inorganic pigment in order to further improve recording sensitivity and recording runnability.

As the inorganic pigment used in the undercoat layer, an oil-absorbing inorganic pigment is preferable from the viewpoint of suppressing adhesion and sticking of dregs to the thermal head. The oil-absorbing inorganic pigment is not particularly limited, but an oil-absorbing inorganic pigment having an oil absorption of 70 ml/100 g or more is preferable, and an oil-absorbing inorganic pigment having an oil absorption of 70 to 150 ml/100 g is more preferable. The oil absorption as referred to herein can be obtained according to the method of JIS K 5101.
Various types of oil-absorbing inorganic pigments can be used, and examples thereof include calcined kaolin, aluminum oxide, magnesium carbonate, amorphous silica, light calcium carbonate, and talc. The average particle size of primary particles of these oil-absorbing inorganic pigments is preferably 0.01 to 5 μm, more preferably 0.02 to 3 μm.
The content of the oil-absorbing inorganic pigment is not particularly limited and can be selected from a wide range.

The organic pigment used in the undercoat layer is not particularly limited, but plastic hollow particles are preferred. Plastic hollow particles can improve recording sensitivity, and improve barrier properties by staying on the support and forming a uniform undercoat layer, so color formers are included in plasticizers and neutral paper. Prevents contact with alkali fillers and suppresses deterioration of coloring ability. The plastic hollow particles are not particularly limited, but for example, hollow non-expandable plastic particles containing a thermoplastic resin as a shell and containing a gas inside, or a foaming agent containing a low boiling point solvent inside. Examples include particles that are expanded by heating to form hollows.
The plastic hollow particles are not particularly limited, but examples include hollow particles whose film material is made of an acrylic resin, a styrene resin, a vinylidene chloride resin, or the like. Further, the hollowness of plastic hollow particles is usually 50 to 99%. Here, the hollow ratio is a value obtained by (d/D)×100, where d indicates the average inner diameter of the plastic hollow particles and D indicates the average outer diameter of the plastic hollow particles. The average particle size of the plastic hollow particles is preferably 0.5 to 10 μm, more preferably 1 to 4 μm, and even more preferably 1 to 3 μm. By setting the average particle size to 10 μm or less, troubles such as streaks and scratches do not occur when the undercoat layer coating liquid is applied by a blade coating method, and good coating suitability can be obtained. Here, the average inner diameter (d) and the average outer diameter (D) of the plastic hollow particles described in the present specification are determined using an electron micrograph obtained by photographing the plastic hollow particles with a scanning electron microscope. (the diameter of the hollow portion of the hollow particle) and the outer diameter, respectively, and the inner diameter and the outer diameter are determined by selecting the longest diameter of each individual particle. Also, the average particle size refers to the median particle size (D50 value) measured by a laser diffraction/scattering particle size distribution analyzer.
The content of the plastic hollow particles is not particularly limited and can be selected from a wide range, but is generally preferably 2 to 90% by mass of the total solid content of the undercoat layer.

The lower limit is more preferably 5% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of improving the effect of color development and enhancing barrier properties. On the other hand, the upper limit is more preferably 80% by mass or less, more preferably 70% by mass or less, particularly preferably 60% by mass or less, and most preferably 50% by mass or less, from the viewpoint of suppressing scum adhesion to the thermal head.

When the oil-absorbing inorganic pigment is used in combination with the plastic hollow particles, the contents of the oil-absorbing inorganic pigment and the plastic should be within the respective ranges described above, and the total amount of the oil-absorbing inorganic pigment and the plastic hollow particles should be within the entirety of the undercoat layer. It is preferably 5 to 90% by mass, more preferably 10 to 90% by mass, even more preferably 10 to 80% by mass of the solid content.

The undercoat layer is generally prepared by mixing and dispersing hollow plastic particles, pigments such as oil-absorbing pigments, binders, auxiliaries, etc. in water as a medium to prepare a coating solution for the undercoat layer. can be formed by coating and drying on a support. The coating amount of the undercoat layer coating liquid is not particularly limited, but the amount is preferably such that the mass per unit area of the undercoat layer after drying is 3 to 20 g/m ² , and 5 to 12 g/m ^{2 .} is more preferable.

The binder contained in the undercoat layer can be appropriately selected from the water-soluble polymers and hydrophobic polymers mentioned as binders contained in the thermal recording composition. In particular, oxidized starch, starch-vinyl acetate graft copolymer, polyvinyl alcohol, styrene-butadiene copolymer and the like are preferable from the viewpoint of improving coating film strength. The content of the binder is not particularly limited and can be selected in a wide range.

The heat-sensitive recording material may optionally be provided with a back layer containing a pigment and an adhesive as main components on the opposite side of the support to the heat-sensitive recording layer. This makes it possible to further improve storage stability, curl aptitude and printer runnability. In addition, various applications in the field of thermosensitive recording material manufacturing, such as applying adhesive treatment to the back surface to process it into an adhesive label, providing a magnetic recording layer, a coating layer for printing, a thermal transfer recording layer, an inkjet recording layer, etc. A known technique can be added as necessary.

The method of applying the dispersion or coating liquid for forming each layer on the support is not particularly limited. , curtain coating, die coating and the like. Further, each dispersion or coating liquid may be coated and dried one by one to form each layer, or the same dispersion or coating liquid may be separately coated and dried to form two or more layers of the same composition. may be formed. Furthermore, two or more layers may be formed by simultaneous multi-layer coating in which two or more dispersion liquids or coating liquids are coated simultaneously.

From the viewpoint of improving the surface properties of the undercoat layer, the coating method for the undercoat layer coating liquid is preferably a blade coating method. As a result, unevenness of the support can be eliminated to form a thermosensitive recording layer having a uniform thickness, and recording sensitivity can be enhanced. In terms of quality, since the surface smoothness of the undercoat layer is further enhanced, curtain coating can be performed with improved coating uniformity of the coating liquid for the thermosensitive recording layer, improving the barrier properties of the overcoat layer provided as necessary. can. The blade coating method is not limited to the coating method using a blade represented by a bevel type or bent type, but also includes pure blade coating, rod blade method, bill blade method, and the like.

The thermosensitive recording layer and the overcoat layer are preferably formed by simultaneous multi-layer coating by curtain coating or the like. Thereby, a uniform coating layer can be formed, the barrier property of the overcoat layer can be improved, and productivity can be enhanced. Curtain coating is a method in which a coating solution is allowed to fall freely and is applied to a support in a non-contact manner. It is not limited. Further, as described in Japanese Patent Application Laid-Open No. 2006-247611 (Patent Document 7), a coating liquid is jetted downward from a curtain head to form a coating liquid layer on an inclined surface, and a downward curtain guide at the end of the inclined surface is formed. It is also possible to form a curtain of coating fluid from the part to transfer the coating fluid layer onto the web surface. In simultaneous multi-layer coating, each layer may be formed by coating after laminating each coating liquid and then drying to form each layer, or after coating the coating liquid for forming the lower layer, the lower layer coated surface is wetted without drying. A coating liquid for forming the upper layer may be applied on the surface coated with the lower layer while the coating is still in place, and then dried to form each layer.

From the viewpoint of increasing the recording sensitivity and improving the image uniformity, a known method such as super calendering or soft calendering is performed after the formation of each layer or after the formation of all layers. may be used for smoothing.

A method for recording information on the heat-sensitive recording material of the present invention may be appropriately selected depending on the purpose, and examples thereof include a thermal head printer, _CO2 laser, semiconductor laser and the like.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited by the following examples. In the examples, "parts" means parts by mass, and "%" means % by mass.
The median particle size of the dispersion liquid in the examples was measured with a laser diffraction/scattering particle size distribution analyzer Microtrac MT3300EXII (manufactured by Microtrac Bell).

尚、［３－（３－フェニルウレイド）フェニル］＝４－メチルベンゼンスルホナートは、特許文献３の記載を参照して合成した。 1. Preparation of thermal recording composition dispersion and production of thermal recording material [Example 1]
(Step 1) Preparation of color developer dispersion liquid [A] A mixture having the following composition was pulverized and dispersed using a bead mill (Labo Star Mini LMZ015) manufactured by Ashizawa Finetech Co., Ltd. to develop a color with a median particle size of 0.7 μm. A dispersion liquid [A] of the agent was prepared.

Incidentally, [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate was synthesized with reference to the description of Patent Document 3.

(Step 2) Preparation of color former dispersion liquid [B] A mixture having the following composition was pulverized and dispersed using a bead mill (Labo Star Mini LMZ015) manufactured by Ashizawa Finetech Co., Ltd. to obtain a color former with a median particle size of 1.0 μm. A dispersion [B] was prepared.

(Step 3) Preparation of Dispersion [C] of Preservability Improver A mixture having the following composition is pulverized and dispersed using a bead mill (Labo Star Mini LMZ015) manufactured by Ashizawa Finetech Co., Ltd., and preserved to a median particle size of 1.0 μm. A dispersion liquid [C] of a property improver was prepared.

(Step 4) Preparation of sensitizer dispersion liquid [D] A mixture having the following composition was pulverized and dispersed using a bead mill (Labo Star Mini LMZ015) manufactured by Ashizawa Finetech Co., Ltd. to obtain a sensitization with a median particle size of 1.0 μm. A dispersion liquid [D] of the agent was prepared.

(Step 5) Preparation of Thermal Recording Composition Dispersions Each of the dispersions [A] to [D] obtained above, calcium carbonate aqueous dispersion, polyvinyl alcohol aqueous solution and zinc stearate aqueous dispersion were mixed with the following compositions. were mixed to prepare a dispersion of the composition for thermal recording.

(Step 6) Preparation of heat-sensitive recording material Dispersion of the heat-sensitive recording composition obtained in Step 5 on high-quality paper having a basis weight of 50 g/m ² so that the mass of the color former when dried is 0.5 g/m ² . After the liquid was applied and dried, calendering was performed to prepare a heat-sensitive recording material.

[Example 2]
A thermosensitive recording composition and a thermosensitive recording material were prepared in the same manner as in Example 1, except that in step 4, diphenylsulfone was changed to 1,2-bis(3-methylphenoxy)ethane (KS-232, Sanko Co., Ltd.). got

[Examples 3 and 4]
Except for changing [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate in step 1 of Examples 1 and 2 to N-[2-(3-phenylureido)phenyl]benzenesulfonamide A thermal recording composition dispersion was prepared in the same manner as in Examples 1 and 2 to prepare a thermal recording material. N-[2-(3-phenylureido)phenyl]benzenesulfonamide was synthesized with reference to the description of Patent Document 4.

[Examples 5 and 6]
[3-(3-Phenylureido)phenyl]4-methylbenzenesulfonate in step 1 of each of Examples 1 and 2 was converted to N-(p-toluenesulfonyl)-N′-(3-p-toluenesulfonyloxyphenyl ) A thermal recording material was prepared by preparing a dispersion of the thermal recording composition in the same manner as in Examples 1 and 2, except that urea was used. Incidentally, N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea was synthesized with reference to the description of Patent Document 5.

[Comparative Example 1]
Example 1 except that the amount of the 67% aqueous calcium carbonate dispersion was changed to 8.2 parts and the amount of the 12% polyvinyl alcohol aqueous solution was changed to 21.9 parts in step 5 without using the [D] solution. A heat-sensitive recording composition and a heat-sensitive recording material for comparison were obtained in the same manner as above.

[Comparative Example 2]
In step 5, without using liquid [C] and liquid [D], the content of 67% calcium carbonate aqueous dispersion was changed to 6.0 parts, and the content of 12% polyvinyl alcohol aqueous solution was changed to 15.9 parts. A thermal recording material was prepared by preparing a dispersion of the thermal recording composition in the same manner as in Example 1 except for the above.

[Comparative Examples 3 and 4]
Except that [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate in step 1 of each of Comparative Examples 1 and 2 was changed to N-[2-(3-phenylureido)phenyl]benzenesulfonamide In the same manner as in Comparative Examples 1 and 2, a thermal recording composition dispersion was prepared to prepare a thermal recording material.

[Comparative Examples 5 and 6]
[3-(3-phenylureido)phenyl] 4-methylbenzenesulfonate in step 1 of each of Comparative Examples 1 and 2 was converted to N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxy A thermal recording material was prepared by preparing a thermal recording composition dispersion in the same manner as in Comparative Examples 1 and 2, except that phenyl)urea was used.

2. Evaluation of thermal responsiveness of each thermosensitive recording material, and durability of printed area and background [color development by dynamic color development sensitivity tester]
The thermal recording materials prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were printed with an applied energy of 0.39 mJ/dot using a thermal printer (TH-M2/PP) manufactured by Okura Engineering Co., Ltd. The optical density (OD value) of the printed portion was measured using a reflection densitometer (trade name: FD-7, manufactured by Konica Minolta, Inc.) under the following conditions. It means that the higher the printing density, the higher the printing density and the better the thermal responsiveness. The results are shown in Tables 1 and 2.
・Measurement conditions Measurement method: Reflection measurement Lighting conditions: C
Observation field of view: 2°
Density white reference: absolute value

[Printed part and background resistance test]
Each thermal recording material obtained in Examples 1 to 6 and Comparative Examples 1 to 6 was printed with an applied energy of 0.39 mJ/dot using a thermal printer (TH-M2/PP) manufactured by Okura Engineering Co., Ltd. , The optical density (OD value) of the printed area and the whiteness of the background were measured using a reflection densitometer (trade name: FD-7, manufactured by Konica Minolta, Inc.) before and after the treatment under each of the conditions shown below. The measurement conditions for the optical density and whiteness are the same as the measurement conditions for the above-mentioned "Print Color Development by Dynamic Color Development Sensitivity Tester".
(1) Processing Conditions for Humidity and Heat Resistance Test Each printed thermosensitive recording material was treated at 40° C. and 90% R.I. H. for 24 hours.
(2) Processing Conditions for Heat Resistance Test Each printed thermosensitive recording material was held at 60° C. for 24 hours using a blower constant temperature thermostat (trade name: DKM-600) manufactured by Yamato Scientific Co., Ltd.
(3) Processing conditions for oil resistance test Two drops of cottonseed oil were dropped on the printed portion of each printed thermosensitive recording material, and the material was allowed to stand at 25°C for 2 hours.
(4) Processing Conditions for Hand Cream Resistance Test A hand cream (containing mineral oil and glycerin) was applied to the printed portion of each printed thermosensitive recording material and left at 25° C. for 4 hours.
(5) Processing conditions for alcohol resistance test Two drops of 70% aqueous ethanol solution were dropped on each printed thermal recording material and wiped off after 30 seconds.
(6) Processing conditions for plasticizer resistance test A vinyl chloride wrap film (containing a plasticizer) was wrapped in one layer on each printed thermosensitive recording material and held at 25°C for 24 hours.

As for the printed part, the residual ratio of the printed part after the test was calculated by the following formula.
Residual rate (%) = (optical density of printed area after test)/(optical density of printed area before test) x 100
The test results are summarized in Tables 1 and 2. In general, if the optical density of the printed portion after processing is 0.80 OD or more, it is easy to visually distinguish, and the whiteness of the background after processing is required to be 80 or more. ing.

From the results in Tables 1 and 2, all of the thermosensitive recording materials of Examples 1 to 6 show excellent thermal responsiveness, oil resistance of the printed area, hand cream resistance, alcohol resistance and plasticizer resistance, and moist heat resistance of the background. , and has excellent heat resistance and alcohol resistance.

According to the present invention, it is possible to provide a thermosensitive recording material which is excellent in thermal responsiveness and storage stability of the printed portion and background.

Claims (13)

A thermal recording composition comprising a color former, a developer, a sensitizer and a stabilizer, wherein the developer is [3-(3-phenylureido)phenyl]=4-methylbenzenesulfonate, N-[2-(3-phenylureido)phenyl]benzenesulfonamide or N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea, as the sensitizer, A thermal recording composition containing diphenylsulfone or 1,2-bis(3-methylphenoxy)ethane and containing 1,3-diphenylurea as the stabilizer. 2. The thermal recording composition according to claim 1, wherein said color former comprises one or more compounds selected from the group consisting of triarylmethane compounds, fluoran compounds, azaphthalide compounds and fluorene compounds. As the color former, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N-ethyl-p-toluidino)-6-methyl-7-anilinofluorane, 3-(N-ethyl- N-isoamylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-(o,p-dimethylanilino)fluorane, 3-pyrrolidino-6-methyl-7-anilino Fluorane, 3-(cyclohexyl-N-methylamino)-6-methyl-7-anilinofluorane, 3-diethylamino-7-(m-trifluoromethylanilino)fluorane, 3-Nn-dibutylamino -6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-(m-methylanilino)fluorane, 3-Nn-dibutylamino-7-(o-chloroanilino)fluorane, 3-( N-ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinofluorane, 3-(N-ethyl-N-ethoxypropylamino)-6-methyl-7-anilinofluorane, 3- one or more fluoran compounds selected from the group consisting of (N-ethyl-N-isobutylamino)-6-methyl-7-anilinofluorane and 3-dipentylamino-6-methyl-7-anilinofluorane The thermal recording composition according to claim 2, comprising 4. The content of the color developer is 1:1 to 5:1 in mass ratio (color developer: color former) to the content of the color former. The composition for heat-sensitive recording according to the above item. The content of the 1,3-diphenylurea is 1:10 to 2.5:1 in mass ratio (1,3-diphenylurea:developer) to the content of the developer. 4. The composition for thermal recording according to claim 1 . 4. Any one of claims 1 to 3 , wherein the content of the sensitizer is 1:5 to 3:1 in mass ratio (sensitizer:developer) to the content of the color developer. The heat-sensitive recording composition according to any one of items. A heat-sensitive recording material having a heat-sensitive recording layer comprising the heat-sensitive recording composition according to claim 1 on a support. 8. The heat-sensitive recording material according to claim 7, wherein said support is fine paper, synthetic paper or plastic film. 9. The heat-sensitive recording material according to claim 7, wherein the heat-sensitive recording layer has a mass per unit area of 1 to 20 g/m ² . 8. The heat-sensitive recording material according to claim 7 , further comprising an undercoat layer containing an organic pigment and/or an inorganic pigment between the support and the heat-sensitive recording layer. 11. The heat-sensitive recording material according to claim 10, wherein said inorganic pigment is an oil-absorbing inorganic pigment having an oil absorption of 70 to 150 ml/100 g. 12. The thermal recording material according to claim 11, wherein said inorganic pigment is calcined kaolin. 11. The heat-sensitive recording material according to claim 10, wherein the organic pigment is plastic hollow particles having an average inner diameter/average outer diameter of 0.5 to 0.99.