JP2006110761A - Thermal recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal recording medium which has a white paper part with high whiteness degree/recording sensitivity, low texture tinting properties under a high temperature/high humidity atmosphere, and excellent environmental resistance. <P>SOLUTION: This thermal recording medium has a thermal color developing layer containing a sheet-like base, a colorless or pale-color dye precursor formed on at least the whole surface of the base and a developer which causes a color to develop through a chemical reaction with the dye precursor by heating. The developer is a chemical compound of a constitution that at least one fluorine atom is bonded with a carbon atom in the β position and/or the γ position of an alcoholic hydroxyl group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat-sensitive recording material that forms a color image by heating. More specifically, the present invention relates to a thermal recording material containing a novel developer, such as image recording paper such as fax paper, cash dispenser paper, boarding ticket, commuter pass, label such as POS label, card such as prepaid card, and the like. The present invention relates to a thermal recording medium useful for a pass ticket.

  In general, a thermal recording material is mainly composed of a coloring material such as an electron-donating leuco dye and an organic acidic substance (developer) such as an electron-accepting phenolic compound on a substrate such as paper, synthetic paper or plastic film. A thermosensitive coloring layer as a component is provided, and a recorded image can be obtained by reacting them with heat energy. Such a heat-sensitive recording material has already been disclosed (for example, see Patent Documents 1 to 3), and has been widely put into practical use.

  In general, the performance required for a thermal recording medium is that the whiteness of the unprinted area (blank area) is high, the whiteness does not decrease under various environments, and the color density of the printed area (recording area) is high. The image once developed is difficult to disappear under various environments, and it is required to satisfy these various requirements depending on the purpose and application. Usually, the main components constituting the heat-sensitive recording layer provided on the sheet-like substrate are leuco dyes, color developers and sensitizers. Among these, the dyes and color developers affect the performance for the above requirements. In particular, it largely depends on the developer. However, most of the compounds put into practical use as color developers are phenolic compounds, and therefore the performance is uniform.

  For example, bisphenol A [2,2′-bis (4-hydroxyphenyl) propane] is a raw material for polyester, and since it is produced in large quantities and is inexpensive, it has been very popular as a color developer for thermal recording materials. However, due to the suspicion of environmental hormone activity, it was hardly used in Japan. Bisphenol S, which is considered to be used as a substitute, has drawbacks such as a high melting point and low sensitivity. Further, 4-hydroxy-4′-isopropoxydiphenyl sulfone (commonly referred to as D-8) (for example, see Patent Document 4), which is widely used at present, is also a phenolic compound and cannot give special characteristics to thermal paper. It is. In addition, a polymolecular condensate of bisphenol S (see, for example, Patent Document 5) has also been proposed, but because of its low sensitivity, it can be used as an auxiliary agent, but it cannot withstand practical use alone.

  On the other hand, non-phenolic developers have hardly been put into practical use, and exceptionally, sulfonylurea compounds (see, for example, Patent Documents 6 and 7) have been put into practical use. With the use of these compounds, it is no exaggeration to say that the image storage stability of thermal paper has reached a level far surpassing conventional performance, and has become a catalyst for the advance of new thermal paper applications. By developing a new type of compound in this way, it becomes possible to give the thermal recording material unprecedented performance, and a wider market may be born.

  The developer of the present invention is a fluorocarbon compound (fluoroalcohol) having an alcoholic hydroxyl group as a color-forming functional group. As a material having a similar chemical structure, a relatively low molecular weight fluoroalcohol compound (for example, However, this is an application as a colorant in a temperature indicating material, and is a liquid at a normal temperature and a normal pressure, or a solid having a relatively low melting point. It is impossible to achieve the required performance.

Japanese Patent Publication No.43-4160 Japanese Examined Patent Publication No. 45-14039 Japanese Patent Publication No. 48-27736 JP 60-13852 A JP-A-8-333329 Japanese Patent Laid-Open No. 5-32061 JP-A-5-147357 JP-A-11-92759 (2nd page)

  It is an object of the present invention to provide a thermal recording medium having a high whiteness in the white portion of the thermal recording medium, excellent recording sensitivity, low white area coloring in a high temperature and high humidity atmosphere, and excellent environmental resistance. It is what.

The present invention includes the following aspects.
(1) Thermal color development comprising a sheet-like substrate, a colorless or light-colored dye precursor formed on at least one surface of the substrate, and a developer that reacts with the dye precursor under heating to develop color. In the heat-sensitive recording material having a layer, the color developer is a compound having a structure in which at least one fluorine atom is bonded to a carbon atom at the β-position and / or γ-position of an alcoholic hydroxyl group. Recorded body.

  (2) The developer has the following structural formula (I):

（ただし、Ｐｈはフェニル基を表す。）
により表される１価の基から選ばれた１員を含む化合物である（１）項に記載の感熱記録体。

(However, Ph represents a phenyl group.)
The thermosensitive recording material according to item (1), which is a compound containing one member selected from a monovalent group represented by formula (1).

  (3) The developer is represented by the following general formula (II):

（ただし、上記式において、Ｒ^１は前記構造式（Ｉ）により表される１価の基を表す。Ｒ^２は単結合、または炭素数１〜２０の２価の有機残基を表し、Ｒ^３は水素原子、ハロゲン原子、炭素数１〜３０の１価の有機残基から選ばれた一員を表す。また、Ｘ^１、Ｘ^２は互いに独立に単結合、または下記構造式（ＩＩＩ）：

(In the above formula, R ¹ represents a monovalent group represented by the structural formula (I). R ² represents a single bond or a divalent organic residue having 1 to 20 carbon atoms; ³ represents a member selected from a hydrogen atom, a halogen atom, and a monovalent organic residue having 1 to 30 carbon atoms, and X ¹ and X ² are each independently a single bond or the following structural formula (III):

により表される２価の基から選ばれた一員を表し、Ｘ^１、Ｘ^２が同時に単結合であるもの、およびフッ素原子が結合した炭素原子に炭素原子以外の原子が接続するものを含まない。さらに、ｐは０〜２の整数を表し、ｐが２の場合、２つのＲ^２、２つのＸ^１はそれぞれ同じであってもよく、また異なっていてもよい。）
により表される化合物である（１）項または（２）項に記載の感熱記録体。

Represents a member selected from a divalent group represented by X ¹ and X ² are simultaneously a single bond and do not include those in which atoms other than carbon atoms are connected to carbon atoms to which fluorine atoms are bonded. . Furthermore, p represents an integer of 0 to 2. When p is 2, two R ^{2 s} and two X ^{1 s} may be the same or different. )
The thermosensitive recording material according to item (1) or (2), which is a compound represented by the formula:

  (4) The developer is represented by the following general formula (IV):

（ただし、上記式において、Ｒ^４は前記構造式（Ｉ）により表される１価の基を表す。Ｒ^５は炭素数１〜２０の２価の有機残基を表し、Ｒ^６は水素原子、ハロゲン原子、炭素数１〜３０の１価の有機残基から選ばれた一員を表す。また、Ｘ^３、Ｘ^４は互いに独立に単結合、または下記構造式（ＩＩＩ）：

(In the above formula, R ⁴ represents a monovalent group represented by the structural formula (I). R ⁵ represents a divalent organic residue having 1 to 20 carbon atoms, and R ⁶ represents a hydrogen atom. Represents a member selected from a halogen atom and a monovalent organic residue having 1 to 30 carbon atoms, and X ³ and X ⁴ are each independently a single bond or the following structural formula (III):

により表される２価の基から選ばれた１員を表す。さらに、ｑは１〜５の整数を表し、ｑが２以上の場合、ベンゼン環上の複数の置換基は互いに同じであってもよく、また異なっていてもよい。）
により表される化合物である（１）項または（２）項に記載の感熱記録体。

1 represents a member selected from divalent groups represented by: Furthermore, q represents an integer of 1 to 5, and when q is 2 or more, a plurality of substituents on the benzene ring may be the same as or different from each other. )
The thermosensitive recording material according to item (1) or (2), which is a compound represented by the formula:

  (5) The developer is represented by the following general formula (V):

（ただし、上式において、Ｒ^７、Ｒ^９は互いに独立に前記構造式（Ｉ）により表される１価の基を表し、Ｒ^８は単結合、または炭素数１〜２０の２価の有機残基を表す。また、Ｘ^５、Ｘ^６は互いに独立に単結合、または下記構造式（ＩＩＩ）：

(In the above formula, R ⁷ and R ⁹ independently represent a monovalent group represented by the structural formula (I), and R ⁸ represents a single bond or a divalent organic group having 1 to 20 carbon atoms. X ⁵ and X ⁶ are each independently a single bond, or the following structural formula (III):

により表される２価の基から選ばれた１員を表し、Ｘ^５、Ｘ^６が同時に単結合であるもの、およびフッ素原子が結合した炭素原子に炭素原子以外の原子が接続するものを含まない。さらに、ｒは１または２を表し、ｒが２の場合、２つのＲ^８、２つのＸ^５はそれぞれ同じであってもよく、また異なっていてもよい。）
により表される化合物である（１）項または（２）項に記載の感熱記録体。

1 member selected from a divalent group represented by the formula, wherein X ⁵ and X ⁶ are simultaneously a single bond, and those in which atoms other than carbon atoms are connected to carbon atoms bonded to fluorine atoms Absent. Furthermore, r represents 1 or 2, and when r is 2, two R ^{8 s} and two X ^{5 s} may be the same or different. )
The heat-sensitive recording material according to item (1) or (2), which is a compound represented by:

  (6) The developer is represented by the following general formula (VI):

（ただし、上式において、Ｒ^１０、Ｒ^１２は互いに独立に前記構造式（Ｉ）により表される１価の基を表し、Ｒ^１１は単結合、または炭素数１〜２０の２価の有機残基を表す。また、Ｘ^７は単結合、または下記構造式（ＩＩＩ）：

(In the above formula, R ¹⁰ and R ¹² independently represent a monovalent group represented by the structural formula (I), and R ¹¹ represents a single bond or a divalent organic group having 1 to 20 carbon atoms. X ⁷ is a single bond or the following structural formula (III):

により表される２価の基から選ばれた１員を表す。さらに、ｓは１〜３の整数を表し、ｓが２以上の場合、複数のＲ^１１、Ｘ^７はそれぞれ同じであってもよく、また異なっていてもよい。）
により表される化合物である（１）項または（２）項に記載の感熱記録体。

1 represents a member selected from divalent groups represented by: Furthermore, s represents an integer of 1 to 3, and when s is 2 or more, the plurality of R ¹¹ and X ⁷ may be the same or different. )
The heat-sensitive recording material according to item (1) or (2), which is a compound represented by:

  The heat-sensitive recording material of the present invention has a high whiteness in the white paper portion, an excellent color density, and a low white paper color development in a high temperature and high humidity atmosphere.

  The heat-sensitive recording material of the present invention uses a compound having a structure in which at least one fluorine atom is bonded to a carbon atom at the β-position and / or γ-position of an alcoholic hydroxyl group as a developer. The heat-sensitive recording layer containing the colorant and the dye precursor is rapidly colored to a high density by heating with a thermal head or the like, and the developed state is maintained and has high image storage stability.

  In the heat-sensitive recording material of the present invention, compounds represented by the general formulas (II), (IV), (V), and (VI) are preferably used as the developer.

R ² in the general formula (II) represents a single bond or a divalent organic residue having 1 to 20 carbon atoms, such as a linear aliphatic group, a cyclic aliphatic group, an aromatic group, or an aliphatic aromatic group. Preferably, it is a linear aliphatic group, 1,4-phenylene group, or 1,3-phenylene group. R ³ represents a hydrogen atom, a halogen atom, or a monovalent organic residue having 1 to 30 carbon atoms, such as a linear aliphatic group, a cyclic aliphatic group, an aromatic group, or an aliphatic aromatic group. Yes, preferably methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, secondary butyl group, tertiary butyl group, isobutyl group, pentyl group, isopentyl group, neopentyl group, tertiary pentyl group, A cyclopentyl group, a hexyl group, a cyclohexyl group, a phenyl group, a benzyl group, a phenethyl group, and the like.

R ⁵ in the general formula (IV) represents a single bond or a divalent organic residue having 1 to 20 carbon atoms, for example, a linear aliphatic group, a cyclic aliphatic group, an aromatic group, or an aliphatic aromatic group. Preferably, it is a linear aliphatic group, 1,4-phenylene group, or 1,3-phenylene group. R ⁶ represents a hydrogen atom, a halogen atom, or a monovalent organic residue having 1 to 30 carbon atoms, such as a linear aliphatic group, a cyclic aliphatic group, an aromatic group, an aliphatic aromatic group, or the like. Yes, preferably methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, secondary butyl group, tertiary butyl group, isobutyl group, pentyl group, isopentyl group, neopentyl group, tertiary pentyl group, And cyclopentyl group, hexyl group, cyclohexyl group, phenyl group, benzyl group, and phenethyl group.

R ⁸ in the general formula (V) represents a single bond or a divalent organic residue having 1 to 20 carbon atoms, for example, a linear aliphatic group, a cyclic aliphatic group, an aromatic group, or an aliphatic aromatic group. Preferred are a linear aliphatic group, a 1,4-phenylene group, a 1,3-phenylene group, and a 4,4′-biphenyl group.

R ¹¹ in the general formula (VI) represents a single bond or a divalent organic residue having 1 to 20 carbon atoms, such as a linear aliphatic group, a cyclic aliphatic group, an aromatic group, or an aliphatic aromatic group. Preferred are a linear aliphatic group, a 1,4-phenylene group, a 1,3-phenylene group, and a 4,4′-biphenyl group.
Further, when R ² , R ³ , R ⁵ , R ⁶ , R ⁸ , R ^11, etc. are linear aliphatic groups, the number of carbons is preferably 1 to 7, and the number of carbons of 8 or more is high. The preservability of the color image under the environment may be inferior.

  As specific examples of the developer of the present invention, the following compounds No. Although (1)-(60) are shown, it is not limited to these. These compounds may be used alone or in combination of two or more thereof. Specific examples of the compounds represented by the general formulas (II), (IV), (V), and (VI) include compound Nos. (1) to (10), Compound No. (11) to (40), Compound No. (41)-(48) and Compound No. (49) to (60) correspond.

  Examples of the compound used as the dye precursor in the heat-sensitive recording layer of the reversible thermosensitive recording material of the present invention include triphenylmethane-based compounds, fluorane-based compounds, diphenylmethane-based compounds, and the like, which can be selected from conventionally known compounds. .

  These dye precursors are, for example, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, 3,3-bis (P-methylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-dibenzylaminobenzo [α] fluorane, 3- (1-ethyl-2-methylindol-3-yl) -3- ( 4-diethylamino-2-n-hexyloxyphenyl-4-azaphthalide, 3- (1-ethyl-2-methylindol-3-yl) -3- (4-diethylamino-2-methylphenyl-4-azaphthalide, 3 -(4-Diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, 3- (2-methyl-1-n-octylindole- 3-yl) -3- (4-diethylamino-2-ethoxyphenyl) -4-azaphthalide, 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluorane, 3-diethylamino -6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluorane, 3- (N-ethyl-Np-toluidino) -6-methyl -7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3- (N-cyclohexyl-N-methylamino) ) -6-methyl-7-anilinofluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7- (m-trifluoromethyla) Lino) fluorane, 3-di (n-pentyl) amino-6-methyl-7-anilinofluorane, 3- [N- (3-ethoxypropyl) -N-ethylamino] -6-methyl-7-ani Linofluorane, 3- (Nn-hexyl-N-ethylamino) -7- (o-chloroanilino) fluorane, 3- (N-ethyl-N-2-tetrahydrofurfurylamino) -6-methyl-7 -Anilinofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methylamino) -3'-methylspiro [phthalide-3,9'-xanthene] -2'-ylamino] phenyl } Propane and 3-dibutylamino-7- (o-chloroanilino) fluorane.

  3,6-dimethoxyfluorane, 3-pyrrolidino-6-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7,8 -Benzofluorane, 3-diethylamino-6,7-dimethylfluorane, 3- (N-methyl-p-toluidino) -7-methylfluorane, 3- (N-methyl-N-isoamylamino) -7, 8-benzofluorane, 3,3′-bis (1-n-amyl-2-methylindol-3-yl) phthalide, 3- (N-methyl-N-isoamylamino) -7-phenoxyfluorane, 3 , 3′-bis (1-n-butyl-2-methylindol-3-yl) phthalide, 3,3′-bis (1-ethyl-2-methylindol-3-yl) fur Lido, 3,3′-bis (p-dimethylaminophenyl) phthalide, 3- (N-ethyl-Np-tolylamino) -7- (N-phenyl-N-methylamino) fluorane, 3-diethylamino-7 -Anilinofluorane, 3-diethylamino-7-benzylaminofluorane, 3-pyrrolidino-7-dibenzylaminofluorane and the like can be selected, but the present invention is not limited thereto, Two or more types may be used in combination.

In the present invention, a phenol, a developer having a sulfonylurea group, or a conventionally known developer composed of an organic acid can be used in combination with the compound of the present invention as long as the desired effect is not inhibited.
Examples of these conventional developers include 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 1,1-bis (4-hydroxyphenyl) -1-phenylethane, and 1,4-bis. (1-Methyl-1- (4′-hydroxyphenyl) ethyl) benzene, 1,3-bis (1-methyl-1- (4′-hydroxyphenyl) ethyl) benzene, dihydroxydiphenyl ether (JP-A-1-180382) ), Benzyl p-hydroxybenzoate (Japanese Patent Laid-Open No. 52-144043), bisphenol S, 4-hydroxy-4′-isopropyloxydiphenyl sulfone (Japanese Patent Laid-Open No. 60-13852), 1,1-di ( 4-hydroxyphenyl) cyclohexane, 1,7-di (4-hydroxyphenylthio) -3,5-dioxahept (JP 59-52694 A), 3,3′-diallyl-4, 4′-dihydroxydiphenyl sulfone (JP 60-208286 A), 2,4-bis (phenylsulfonyl) phenol (special Kaihei 8-269000).

  Further, as a developer other than phenol, N- (p-toluenesulfonyl) -N′-phenylurea, N- (p-toluenesulfonyl) -N′-, which is disclosed in JP-A-5-32601. (P-methoxyphenyl) urea, N- (p-toluenesulfonyl) -N ′-(o-tolyl) urea, N- (p-toluenesulfonyl) -N ′-(m-tolyl) urea, N- (p -Toluenesulfonyl) -N '-(p-tolyl) urea, N- (p-toluenesulfonyl) -N'-(o-chlorophenyl) urea, N- (benzenesulfonyl) -N'-phenylurea, N- ( p-chlorobenzenesulfonyl) -N′-phenylurea or 4,4-bis (p-toluenesulfonylaminocarbonylamino) diphenylmethane disclosed in JP-A-5-147357 1,8 (3,6-di oxa octylene) bis (4-(p-toluenesulfonyl aminocarbonyl amino) compound having a sulfonylurea group such as benzoate and the like.

  Furthermore, in the present invention, a conventionally known heat-fusible substance (sensitizer) can be used in combination as long as the desired effect is not impaired. Typical examples thereof include 1-hydroxy-2-naphthoic acid phenyl ester (Japanese Patent Laid-Open No. 57-91089), p-benzylbiphenyl (Japanese Patent Laid-Open No. 60-82382), benzyl naphthyl ether (specialty). No. 58-87094), dibenzyl terephthalate (Japanese Patent Laid-Open No. 58-98285), benzyl p-benzyloxybenzoate (Japanese Patent Laid-Open No. 57-201691), diphenyl carbonate, ditolyl carbonate (Japanese Patent Laid-Open No. 58-136489), m-terphenyl (Japanese Patent Laid-Open No. 57-89994), 1,2-bis (m-tolyloxy) ethane (Japanese Patent Laid-Open No. 60-56588), 1,5-bis ( p-methoxyphenoxy) -3-oxapentane (Japanese Patent Laid-Open No. 62-181183), oxalic acid diesters (Japanese Patent Laid-Open No. Sho 64-64) 583 JP), 1,4-bis (p- tolyloxy) and the like benzene (JP-A-2-153783).

  The heat-sensitive coloring layer of the heat-sensitive recording material of the present invention can further contain waxes, and preferably contains organic or inorganic pigments. The thermosensitive coloring layer further contains a binder for fixing these components to the sheet-like substrate.

  In general, the content of the leuco dye in the thermosensitive coloring layer in the thermosensitive coloring layer is preferably 5 to 20% by mass of the dry mass of the thermosensitive coloring layer. In general, the content of the developer of the present invention is preferably 5 to 50% by mass. If the content is less than 5% by mass, the developing ability may be insufficient. If the content exceeds 50% by mass, the developing ability will be saturated and no particular improvement will be seen, which may be economically disadvantageous. There is. Further, when a sensitizer is contained, the addition of less than 5% by mass may reduce the sensitization effect. Even if the addition exceeds 50% by mass, the sensitization effect is saturated, and a further increase in sensitivity can be expected. Therefore, 5 to 50% by mass is preferable, and 10 to 40% by mass is more preferable.

  When the heat-sensitive color developing layer contains a conventionally known phenol-based, organic acid-based, or sulfonylurea-based developer, the content is preferably 5 to 40% by mass. When waxes and white pigments are contained in the thermosensitive coloring layer, the content is preferably 2 to 20% by mass and 2 to 50% by mass, respectively, and the content of the binder is generally 5 to 20% by mass. .

Examples of the organic or inorganic pigment include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, calcined clay, talc, and surface-treated calcium carbonate and silica. In addition to these inorganic fine powders, organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be used.
Examples of waxes that can be used include known paraffins, amide waxes, bisimide waxes, and higher fatty acid metal salts.

  The binder can be selected from water-soluble polymers, water-dispersible polymers, water-insoluble polymers, active energy ray-curable compounds, and the like.

  Examples of water-soluble polymers and water-dispersible polymers include polyvinyl alcohols of various molecular weights and derivatives thereof (for example, acetoacetyl group-modified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, sulfonyl group-modified polyvinyl alcohol, etc.), starch And derivatives thereof (for example, oxidized starch, vinyl acetate graft starch, aldehyde-modified starch, etc.), cellulose derivatives (methoxycellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, etc.), polyacrylic acid soda, polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester Polymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate Water-soluble polymer materials such as gelatin, gelatin, and casein, and polyvinyl acetate, polyurethane, styrene / butadiene copolymers, polyacrylic acid, polyacrylate esters, vinyl chloride / vinyl acetate copolymers, polybutyl methacrylate Latex such as ethylene / vinyl acetate copolymer and styrene / butadiene / acrylic copolymer can be used. These polymers may be used alone or in combination of two or more thereof, and are not limited to the examples listed here.

Examples of water-insoluble polymers include phenoxy resin, cellulose acetate butyrate resin, polyurethane resin, polyester resin, (meth) acrylic resin, styrene / (meth) acrylic copolymer, vinyl chloride / vinyl acetate copolymer Polycarbonate resins and the like, and these are usually used after being dissolved in a suitable organic solvent. These resins may be used alone or in combination of two or more thereof, and are not limited to the examples listed here.
In addition, by using resins modified to have hydroxyl groups in these polymers, and further adding a compound having a plurality of isocyanate groups in the molecule as a crosslinking agent to cure the resin, heat-sensitive recording with excellent durability The body is obtained. The addition amount of the crosslinking agent is appropriately determined depending on the amount of hydroxyl groups in the resin and the number of isocyanate groups in the crosslinking agent to be used.

  Examples of the compound used as the crosslinking agent include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,5-naphthalene. Diisocyanate, p-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 3,3′-dimethyl-4,4′-diphenylmethane diisocyanate, 4,4′-biphenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, Methylene bis (4-cyclohexyl isocyanate), hydrogenated diphenylmethane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, bis (2-isocyana) Ethyl) fumarate, 6-isopropyl-1,3-phenyl diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, etc. polymethylene polyphenyl isocyanate. These crosslinking agents may be used alone or in admixture of two or more thereof, and are not limited to the examples listed here.

Examples of the active energy ray-curable compounds can be selected from the following compounds, but these may be used alone or in combination of two or more thereof, and are limited to the examples listed here. It is not a thing.
(1) Alcohol and polyalkylene glycol acrylate (or methacrylate) compounds such as aliphatic, alicyclic, and aromatic. (2) Acrylate (or methacrylate) compounds obtained by adding an alkylene oxide to an alcohol such as aliphatic, alicyclic, and aromatic. (3) Polyacryloyl (or methacryloyl) alkyl phosphate esters. (4) A reaction product of a polybasic acid, a polyol, and acrylic (or methacrylic) acid. (5) Reaction product of isocyanate, polyol, and acrylic (or methacrylic) acid. (6) A reaction product of an epoxy compound and acrylic (or methacrylic) acid. (7) A reaction product of an epoxy compound, a polyol, and acrylic (or methacrylic) acid. (8) Amides composed of amines such as aliphatic, alicyclic and aromatic, or nitrogen-containing cyclic compounds and acrylic acid (or methacrylic acid).

When the active energy ray-curable compounds are cured by ultraviolet irradiation, an appropriate amount of a photoinitiator is added, and an ultraviolet irradiation device having a high-pressure mercury lamp, a xenon lamp, or a metal halide lamp is used as an irradiation light source. Is determined as necessary.
Examples of photoinitiators include acetophenone, benzophenone, benzoin ether, chloroacetophenone, diethoxyacetophenone, hydroxyacetophenone, α-aminoacetophenone, benzyl methyl ketal, thioxanthone, α-acyl oxime ester, acyl phosphine oxide, glyoxy ester, Examples include, but are not limited to, 3-ketocoumarin, 2-ethylanthraquinone, camphorquinone, benzyl, Michler's ketone, and the like.

  In addition, when the active energy ray-curable compounds are cured by electron beam irradiation, the electron beam accelerator to be used is not particularly limited, and for example, a bandegraft scanning method, a double scanning method, a curtain beam, etc. Although an electron beam irradiation apparatus such as a system can be used, a curtain beam system that is relatively inexpensive and can provide a large output is effectively used. The acceleration voltage during electron beam irradiation is preferably 100 to 300 kV, and the absorbed dose is preferably 0.1 to 9 Mrad. The oxygen concentration in the atmosphere during electron beam irradiation is preferably 500 ppm or less. If the oxygen concentration exceeds 500 ppm, oxygen may act as a retarder for the polymerization reaction, and the electron beam curable resin may be insufficiently cured.

The sheet-like substrate used in the heat-sensitive recording material of the present invention is made of paper (including acidic papermaking paper and neutral papermaking paper), coated paper coated with pigment, latex, etc. on the surface, laminated paper, and polyolefin resin. You can choose from synthetic paper, plastic film, etc. On at least one surface of such a sheet-like substrate, a coating solution containing the mixture of the required components is applied and dried to produce a heat-sensitive recording material. The coating amount is preferably from 1 to 15 g / ^{m 2} in a state where the coating liquid layer has dried, 2 to 10 g / ^{m 2} is particularly preferred.

In the thermosensitive recording material of the present invention, a coating layer such as a protective layer or a printing layer can be further formed on the thermosensitive coloring layer.
An undercoat layer containing a pigment (preferably an oil-absorbing pigment) and an adhesive can be provided between the sheet-like substrate and the thermosensitive coloring layer.

Hereinafter, the present invention will be specifically described with reference to examples. Unless otherwise specified, “parts” and “%” represent “parts by mass” and “% by mass”, respectively.
In the following synthesis examples, unless otherwise stated, all reaction vessels are flasks equipped with reflux condensers, all organic solvents are subjected to dehydration operations such as distillation, and water is distilled water. used. Unless otherwise specified, the reaction was carried out under an inert gas stream.

<Synthesis Example 1>
Synthesis method of 1- (p-benzoylamino) phenyl-2,2,2-trifluoroethanol (Compound No. 21):
4-Nitrobenzaldehyde (15.1 g) and triethylamine (2.0 g) are dissolved in dimethylformamide (100 mL), and trifluoromethyltrimethylsilane (14.2 g) is added dropwise. After stirring at room temperature for 17 hours, 3N hydrochloric acid (10 mL) is added, and the mixture is stirred at room temperature for 30 minutes. Water (200 mL) is further added, followed by extraction three times with ethyl acetate (150 mL) (using a total of 450 mL). The organic layer is collected, dried over anhydrous magnesium sulfate, filtered, and concentrated under reduced pressure until the volume is about 100 mL. To this solution, palladium on activated carbon (5.0 g) is stirred for 3 hours under pressure of 200 kPa of hydrogen gas in a pressure reactor. After filtering the reaction solution, the solution is concentrated under reduced pressure until the filtrate becomes about 50 mL, and n-hexane (100 mL) is added to the residue while stirring to precipitate crystals. The precipitated crystals are collected by filtration and dried under reduced pressure to give 1- (p-aminophenyl) -2,2,2-trifluoroethanol as an intermediate as a colorless powder (14.3 g). The yield based on p-nitrobenzaldehyde was 75%.

  The above intermediate 1- (p-aminophenyl) -2,2,2-trifluoroethanol (9.56 g) was dissolved in tetrahydrofuran (100 mL), pyridine (7.91 g) was further added, and this solution was ice-cooled. Then, benzoyl chloride (7.0 g) is added dropwise. After completion of dropping, the reaction solution is returned to room temperature and stirred for 24 hours. 3N hydrochloric acid (20 mL) is added dropwise to the reaction mixture, and the mixture is stirred for 1 hour, extracted with toluene (300 mL), the organic layer is washed with water, and dried over anhydrous magnesium sulfate (20 g). After the anhydrous magnesium sulfate was filtered off, the filtrate was concentrated under reduced pressure to give 1- (p-benzoylamino) phenyl-2,2,2-trifluoroethanol (Compound No. 21) as the white solid (14. 0 g). The yield based on 1- (p-aminophenyl) -2,2,2-trifluoroethanol was 95%.

The analytical values of this crystal are as follows.
Melting point: 164.5 ° C
Results of NMR measurement (in DMSO-d6) (numbers are in ppm);
δ 5.09 (m, 1H), 6.77 (s, 1H), 7.45 (d, 2H), 7.52 (m, 2H), 7.59 (m, 1H), 7.79 (d , 2H), 7.94 (d, 2H), 10.31 (s, 1H)

<Synthesis Example 2>
Synthesis method of N- {p- (1-hydroxy-2,2,2-trifluoroethyl) phenyl} -N′-cyclohexylurea (Compound No. 29):
1- (p-aminophenyl) -2,2,2-trifluoroethanol (9.56 g) synthesized according to Synthesis Example 1 above was dissolved in tetrahydrofuran (100 mL), and this solution was cooled with ice while cyclohexyl isocyanate ( 6.26 g) is added dropwise. After completion of dropping, the reaction solution is returned to room temperature and stirred for 24 hours. The precipitated crystals were collected by filtration to obtain N- {p- (1-hydroxy-2,2,2-trifluoroethyl) phenyl} -N′-cyclohexylurea (Compound No. 29) as a white solid (Compound No. 29). 15.5 g). The yield based on 1- (p-aminophenyl) -2,2,2-trifluoroethanol was 98%.

The analytical values of this crystal are as follows.
Melting point: 180.9 ° C
Results of NMR measurement (in DMSO-d6) (numbers are in ppm);
δ 1.16 (m, 3H), 1.28 (m, 2H), 1.51 (m, 1H), 1.64 (m, 2H), 1.79 (m, 2H), 3.43 (m , 1H), 5.00 (m, 1H), 6.09 (d, 1H), 6.64 (d, 1H), 7.30 (d, 2H), 7.37 (d, 2H), 8 .37 (s, 1H)

<Synthesis Example 3>
Synthesis method of p-benzoylamino-α, α-bistrifluoromethylbenzyl alcohol (Compound No. 31):
4- (Hexafluoro-2-hydroxyisopropyl) aniline (13.0 g) was dissolved in tetrahydrofuran (150 mL), pyridine (7.91 g) was further added, and this solution was cooled with ice while benzoic acid chloride (7.0 g) was added. ) Is dripped. After completion of dropping, the reaction solution is returned to room temperature and stirred for 24 hours. 3N hydrochloric acid (20 mL) is added dropwise to the reaction mixture, and the mixture is stirred for 1 hour, extracted with toluene (400 mL), and the organic layer is washed with water and dried over anhydrous magnesium sulfate (30 g). After filtering off anhydrous magnesium sulfate, the filtrate is concentrated under reduced pressure to obtain the target product p-benzoylamino-α, α-bistrifluoromethylbenzyl alcohol (Compound No. 31) as a white solid (17.6 g). . The yield based on 1- (p-aminophenyl) -2,2,2-trifluoroethanol was 97%.

The analytical values of this crystal are as follows.
Melting point: 173.8 ° C
Results of NMR measurement (in DMSO-d6) (numbers are in ppm);
δ 7.53 (t, 2H), 7.60 (t, 1H), 7.64 (d, 2H),
7.90 (d, 2H), 7.95 (d, 2H),
8.64 (s, 1H), 10.45 (s, 1H)

<Synthesis Example 4>
Synthesis method of N, N′-bis {p- (1-hydroxy-2,2,2-trifluoroethyl) phenyl} oxalic acid diamide (Compound No. 52):
1- (p-aminophenyl) -2,2,2-trifluoroethanol (9.56 g) synthesized according to Synthesis Example 1 was dissolved in tetrahydrofuran (100 mL), and pyridine (7.91 g) was further added. Oxalic acid dichloride (3.17 g) is added dropwise while the solution is ice-cooled. After completion of dropping, the reaction solution is returned to room temperature and stirred for 24 hours. 3N hydrochloric acid (20 mL) is added dropwise to the reaction mixture, and the mixture is stirred for 1 hour, extracted with toluene (300 mL), the organic layer is washed with water, and dried over anhydrous magnesium sulfate (20 g). After filtering off anhydrous magnesium sulfate, the filtrate was concentrated under reduced pressure, and the target N, N′-bis {p- (1-hydroxy-2,2,2-trifluoroethyl) phenyl} oxalic acid diamide (compound) No. 52) is obtained as a white solid (10.0 g). The yield based on oxalic acid dichloride was 92%.

The analytical values of this crystal are as follows.
Melting point: 253.6 ° C
Results of NMR measurement (in DMSO-d6) (numbers are in ppm);
δ 5.13 (m, 2H), 6.80 (d, 2H), 7.48 (d, 4H), 7.87 (d, 4H), 10.92 (s, 2H)

Example 1
A thermal recording paper was prepared by the following operation.
(1) Preparation of pigment undercoat paper To a dispersion obtained by dispersing 85 parts of calcined clay (trade name: Ansilex, Engel Hard Minerals) in 320 parts of water, a styrene-butadiene copolymer emulsion (solid min 50%) 40 parts, the coating liquid obtained by mixing 10% aqueous solution of oxidized starch 50 parts, as the coating amount after drying over the base paper 48 g / ^{m 2} is 7.0 g / ^{m 2} coating To obtain a pigment-primed paper.

(2) Preparation of dispersion A
Component amount (parts)
3- (Di-n-butylamino) -6-methyl-7-anilinofluorane 20
Polyvinyl alcohol 10% aqueous solution 10
Water 70
The composition was pulverized using a sand grinder until the average particle size became 1 μm or less.

(3) Preparation of dispersion B
Component amount (parts)
1- (p-benzoylamino) phenyl-2,2,2
-Trifluoroethanol (Compound No. 21) 20
Polyvinyl alcohol 10% aqueous solution 10
Water 70
The composition was pulverized using a sand grinder until the average particle size became 1 μm or less.

(4) Preparation of dispersion C
Component amount (parts)
Oxalic acid di p-methylbenzyl ester 20
Polyvinyl alcohol 10% aqueous solution 10
Water 70
The composition was pulverized using a sand grinder until the average particle size became 1 μm or less.

(5) Formation of coloring layer 60 parts A, 120 parts B, 120 parts C, 23 parts kaolinite pigment (trade name: HG clay, manufactured by Huber), 20 parts 25% zinc stearate dispersion, 15 parts of a 30% paraffin dispersion and 120 parts of a 10% polyvinyl alcohol aqueous solution were mixed and stirred to obtain a coating solution. This coating solution was applied and dried on the pigment-coated surface of the pigment undercoat paper so that the coating amount after drying was 5.0 g / m ² to form a thermosensitive coloring layer, and a thermosensitive recording paper was prepared.

(6) Supercalender treatment The thermal recording paper obtained as described above was treated with a supercalender, and the Beck smoothness of the surface was set to 800 to 1000 seconds.

(7) Various tests (a) Whiteness About the said thermosensitive recording paper sample, the whiteness was measured using the Hunter whiteness meter (made by Toyo Seiki Seisakusho).
(B) Color development test The thermal recording paper thus obtained was subjected to a sample using a dynamic thermal color development simulator (trade name: THPMD, manufactured by Okura Electric Co., Ltd.) under printing conditions of a printing voltage of 21.7 V and an applied pulse width of 1.0 ms. Was colored in a checkered pattern. The color density was measured with a Macbeth reflection densitometer (trade name: RD-914, manufactured by Gretag Macbeth), and this was used as a representative value of recording sensitivity.

(C) White paper portion wet-resistant color development test The above thermal recording paper sample is placed in a thermo-hygrostat adjusted to 40 ° C. and 90% RH for 24 hours, and the density of the white paper portion (white background density) is the same as in (b) above. It was measured.

(D) White paper part heat resistant ground color test The above-mentioned thermal recording paper sample was put in a thermostat at 60 ° C. for 24 hours, and the density of the white paper part was measured in the same manner as in the above (b).

Example 2
The same operation as in Example 1 was performed. However, in the preparation of dispersion B, N- {p- (1-hydroxy-2,2) was used instead of 1- (p-benzoylamino) phenyl-2,2,2-trifluoroethanol (Compound No. 21). 2,2-trifluoroethyl) phenyl} -N′-cyclohexylurea (Compound No. 29) was used. The test results are shown in Table 1.

Example 3
The same operation as in Example 1 was performed. However, in preparing the dispersion B, p-benzoylamino-α, α-bistrifluoromethyl was used instead of 1- (p-benzoylamino) phenyl-2,2,2-trifluoroethanol (Compound No. 21). Benzyl alcohol (Compound No. 31) was used. The test results are shown in Table 1.

Example 4
The same operation as in Example 1 was performed. However, in preparing the dispersion B, N, N′-bis {p- (1- (1-benzoylamino) phenyl-2,2,2-trifluoroethanol (compound No. 21)) was used instead of 1- (p-benzoylamino) phenyl-2,2,2-trifluoroethanol (compound No. 21). Hydroxy-2,2,2-trifluoroethyl) phenyl} oxalic acid diamide (Compound No. 52) was used. The test results are shown in Table 1.

Comparative Example 1
The same operation as in Example 1 was performed. However, in preparing dispersion B, 2,2-bis (4-hydroxyphenyl) propane was used instead of 1- (p-benzoylamino) phenyl-2,2,2-trifluoroethanol (compound No. 21). (Bisphenol A) was used. The test results are shown in Table 1.

前記表１から明らかなように、本発明の感熱記録体は、白紙部の白色度が高く、発色濃度が高く、かつ高温高湿雰囲気下での白紙部地発色が低い。

As is apparent from Table 1, the thermal recording material of the present invention has a high whiteness in the white paper portion, a high color density, and a low white paper color development in a high temperature and high humidity atmosphere.

The heat-sensitive recording material of the present invention has an excellent color density, low white paper color development in a high-temperature and high-humidity atmosphere, excellent environmental resistance, and extremely high practical value.

Claims (6)

  A sheet-like substrate, a colorless or light-colored dye precursor formed on at least one surface of the substrate, and a thermosensitive coloring layer containing a developer that reacts with the dye precursor to develop color by heating A heat-sensitive recording material according to claim 1, wherein the developer is a compound having a structure in which at least one fluorine atom is bonded to a carbon atom at the β-position and / or γ-position of an alcoholic hydroxyl group. The developer has the following structural formula (I) in the molecule:

(However, Ph represents a phenyl group.)
The heat-sensitive recording material according to claim 1, which is a compound containing one member selected from a monovalent group represented by: The developer is represented by the following general formula (II):

(In the above formula, R ¹ represents a monovalent group represented by the structural formula (I). R ² represents a single bond or a divalent organic residue having 1 to 20 carbon atoms; ³ represents a member selected from a hydrogen atom, a halogen atom, and a monovalent organic residue having 1 to 30 carbon atoms, and X ¹ and X ² are each independently a single bond or the following structural formula (III):

Represents a member selected from a divalent group represented by X ¹ and X ² are simultaneously a single bond and do not include those in which atoms other than carbon atoms are connected to carbon atoms to which fluorine atoms are bonded. . Furthermore, p represents an integer of 0 to 2. When p is 2, two R ^{2 s} and two X ^{1 s} may be the same or different. )
The heat-sensitive recording material according to claim 1, which is a compound represented by the formula: The developer is represented by the following general formula (IV):

(In the above formula, R ⁴ represents a monovalent group represented by the structural formula (I). R ⁵ represents a divalent organic residue having 1 to 20 carbon atoms, and R ⁶ represents a hydrogen atom. Represents a member selected from a halogen atom and a monovalent organic residue having 1 to 30 carbon atoms, and X ³ and X ⁴ are each independently a single bond or the following structural formula (III):

1 represents a member selected from divalent groups represented by: Furthermore, q represents an integer of 1 to 5, and when q is 2 or more, a plurality of substituents on the benzene ring may be the same as or different from each other. )
The heat-sensitive recording material according to claim 1, which is a compound represented by the formula: The developer is represented by the following general formula (V):

(In the above formula, R ⁷ and R ⁹ independently represent a monovalent group represented by the structural formula (I), and R ⁸ represents a single bond or a divalent organic group having 1 to 20 carbon atoms. X ⁵ and X ⁶ are each independently a single bond, or the following structural formula (III):

1 member selected from a divalent group represented by the formula, wherein X ⁵ and X ⁶ are simultaneously a single bond, and those in which atoms other than carbon atoms are connected to carbon atoms bonded to fluorine atoms Absent. Furthermore, r represents 1 or 2, and when r is 2, two R ^{8 s} and two X ^{5 s} may be the same or different. )
The heat-sensitive recording material according to claim 1, which is a compound represented by the formula: The developer is represented by the following general formula (VI):

(In the above formula, R ¹⁰ and R ¹² independently represent a monovalent group represented by the structural formula (I), and R ¹¹ represents a single bond or a divalent organic group having 1 to 20 carbon atoms. X ⁷ is a single bond or the following structural formula (III):

1 represents a member selected from divalent groups represented by: Furthermore, s represents an integer of 1 to 3, and when s is 2 or more, the plurality of R ¹¹ and X ⁷ may be the same or different. )
The heat-sensitive recording material according to claim 1, which is a compound represented by the formula: