JP2010143078A - Diphenylsulfone derivative and thermosensitive recording material containing diphenylsulfone derivative - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer and an image stabilizer that can provide a thermosensitive recording material excelling in preservability of an image part, particularly in oil resistance and plasticizer resistance, further excelling in preservability of a color undeveloped part, particularly in heat resistance, and to provide the thermosensitive recording material excelling in preservability using the developer and the image stabilizer. <P>SOLUTION: The thermosensitive recording material is formed by providing, on a support body, a thermosensitive color-developing layer containing the developer, leuco dye and a diphenylsulfone derivative of different structure as the image stabilizer, wherein the developer is a mixture of a diphenylsulfone-crosslinked compound and a diphenylsulfone derivative which is a reaction product of dihydroxydiphenylsulfone and 4,4'-bis(halo methyl)biphenyl, in which at least one of terminal groups is a halogenated methyl group. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a diphenylsulfone derivative having an effect as a developer, a developer, an image stabilizer for thermal recording, and a thermal recording material. More specifically, the diphenylsulfone derivative (a) useful as a developer capable of providing a heat-sensitive recording material excellent in storage stability of an image area and storage stability of an uncolored area, useful as an image stabilizer for thermal recording. The present invention relates to a heat-sensitive recording material having the above-mentioned excellent properties, comprising a diphenylsulfone derivative, a developer for heat-sensitive recording comprising the diphenylsulfone derivative (a) and a diphenylsulfone cross-linking compound.

  A heat-sensitive recording material generally comprises a support on which a heat-sensitive color-developing layer mainly comprising an electron-donating colorless or light-colored dye precursor and an electron-accepting developer is provided. By heating with laser light or the like, the dye precursor and the developer react instantaneously to obtain a recording material. Such heat-sensitive recording materials have been developed for a long time. For example, a heat-sensitive copying material made of a composition that is usually colorless by applying a special coating to the paper surface, but develops color by heating or infrared irradiation. As a sheet, there has been proposed a heat-sensitive copying sheet in which a reaction developing component comprises a lactone, lactam or sultone type non-colored dye base, an organic acid and a heat-fusible substance (see Patent Document 1). Further, as a heat-sensitive recording material having improved moisture resistance and print stability, and capable of preventing coloring during drying and production of the recording forming component applied by the improvement of moisture resistance, the recording forming unit has crystal violet lactone and It consists of a support sheet material having a phenolic substance. The phenolic substance is solid at room temperature, liquefied or vaporized at a thermographic temperature, reacts with a lactone to produce a record, and the lactone and the phenolic substance are contained in polyvinyl alcohol. A dispersed thermal recording material has been proposed (see Patent Document 2).

Such heat-sensitive recording materials have advantages such that recording can be obtained with a relatively simple device, maintenance is easy, noise generation is low, thermal printers such as various portable terminals, ultrasonic echoes, etc. It is used for medical image printers, thermopen recorders such as electrocardiograms and analytical instruments, air tickets, boarding tickets, and POS labels for products.
Thermosensitive recording materials are required to have various characteristics such as excellent color developability, high color density with low heat, excellent preservation of the resulting image, and whiteness of the uncolored areas. Is done. In particular, storage stability such as plasticizer resistance, moisture resistance, and heat resistance is required for microwave processed food labels, parking tickets, delivery labels, tickets, and the like because the reliability of recorded images is important. For this reason, various compounds have been studied as color developers for heat-sensitive recording materials.

For example, α, α′-bis [4- (p-) is a color developer that provides a heat-sensitive recording material with high sensitivity and little fogging of the background and excellent recording image storage stability, particularly water resistance and plasticizer resistance. Hydroxyphenylsulfonyl) phenoxy] -p-xylene, α, α′-bis [4- (p-hydroxyphenylsulfonyl) phenoxy] -m-xylene or α, α′-bis [4- (p-hydroxyphenylsulfonyl) A heat-sensitive recording material containing phenoxy] -o-xylene has been proposed (see Patent Document 3). In addition, as a developer for thermosensitive recording materials with excellent storage stability of color images, especially plasticizer resistance, oil resistance, light resistance, and heat and humidity resistance, dihydroxydiphenyl sulfone and alkylene dichloride, α, α'-dichloroxylene, etc. A diphenylsulfone cross-linking compound that is a reaction product with the above is exemplified (see Patent Document 4). However, these compounds have insufficient heat resistance of the uncolored portion, and it cannot be said that the requirement for high storage stability of the developer is sufficiently satisfied.
Japanese Patent Publication No.43-4160 Japanese Examined Patent Publication No. 45-14039 JP-A-7-149713 Japanese Patent Laid-Open No. 10-29969

  Under such circumstances, the present invention provides a heat-sensitive recording material that is excellent in storage stability of an image area, particularly oil resistance and plasticizer resistance, and further excellent in storage stability of an uncolored area, particularly heat resistance. It is an object of the present invention to provide a developer and an image stabilizer that can be used, and to provide a heat-sensitive recording material excellent in the above-described storage stability using the developer and the image stabilizer. It is a thing.

（式中、Ｘはハロゲン原子を表し、ｎは１以上の整数を表す。）

（式中、Ｙはハロゲン原子を表し、ｐは１以上の整数を表す。）
［２］上記[１]項に記載のジフェニルスルホン誘導体と、下記一般式（３）で表されるジフェニルスルホン架橋型化合物との混合物、

（式中、ｍは１以上の整数を表す。）
［３］無色又は淡色のロイコ染料からなる発色物質と顕色剤とを含有する感熱発色層を支持体上に設けてなる感熱記録材料であって、前記顕色剤として、前記一般式（１）で表されるジフェニルスルホン誘導体と前記一般式（３）で表されるジフェニルスルホン架橋型化合物との混合物を含有することを特徴とする感熱記録材料、
［４］無色又は淡色のロイコ染料からなる発色物質と顕色剤及び画像安定化剤とを含有する感熱発色層を支持体上に設けてなる感熱記録材料であって、上記画像安定化剤として、前記一般式（２）で表されるジフェニルスルホン誘導体を含有することを特徴とする感熱記録材料、及び
［５］無色又は淡色のロイコ染料からなる発色物質、顕色剤及び画像安定化剤とを含有する感熱発色層を支持体上に設けてなる感熱記録材料であって、上記顕色剤として、前記一般式（１）で表されるジフェニルスルホン誘導体と上記一般式（３）で表されるジフェニルスルホン架橋型化合物との混合体を用い、かつ画像安定化剤として、前記一般式（２）で表されるジフェニルスルホン誘導体を含有することを特徴とする感熱記録材料、
を提供するものである。 As a result of intensive studies to solve the above problems, the present inventors have found that the problem can be solved by a diphenylsulfone derivative having a specific structure, and based on this finding, the present invention is completed. It came.
That is, the present invention
[1] A reaction product of dihydroxydiphenylsulfone and 4,4′-bis (halomethyl) biphenyl, wherein at least one of the end groups is a halogenated methyl group, the following general formula (1) or general formula ( 2) a diphenylsulfone derivative represented by

(In the formula, X represents a halogen atom, and n represents an integer of 1 or more.)

(In the formula, Y represents a halogen atom, and p represents an integer of 1 or more.)
[2] A mixture of the diphenylsulfone derivative according to the above [1] and a diphenylsulfone cross-linked compound represented by the following general formula (3):

(In the formula, m represents an integer of 1 or more.)
[3] A heat-sensitive recording material in which a heat-sensitive color-developing layer containing a color-developing material composed of a colorless or light leuco dye and a developer is provided on a support, and the developer represented by the general formula (1) A heat-sensitive recording material comprising a mixture of a diphenylsulfone derivative represented by formula (3) and a diphenylsulfone cross-linking compound represented by the general formula (3),
[4] A heat-sensitive recording material comprising a heat-sensitive color-developing layer containing a color-developing substance comprising a colorless or light-colored leuco dye, a developer, and an image stabilizer on a support, and the image stabilizer A heat-sensitive recording material comprising a diphenylsulfone derivative represented by the general formula (2), and [5] a color developing material, a color developer and an image stabilizer comprising a colorless or light leuco dye, A heat-sensitive recording material comprising a heat-sensitive color-developing layer containing a diphenylsulfone derivative represented by the general formula (1) and the general formula (3) as the developer. A heat-sensitive recording material comprising a diphenylsulfone derivative represented by the general formula (2) as an image stabilizer, and a mixture with a diphenylsulfone cross-linking compound.
Is to provide.

  According to the diphenylsulfone derivative of the present invention, it is possible to obtain a heat-sensitive recording material that is excellent in storage stability of an image area, particularly oil resistance and plasticizer resistance, and further excellent in storage stability of an uncolored area, particularly heat resistance. .

（式中、Ｘはハロゲン原子を表し、ｎは１以上の整数を表す。）
この一般式（１）で表されるジフェニルスルホン誘導体（ａ）は、末端基の一方がフェノール性水酸基からなり、もう一方がハロゲン化メチル基からなるジフェニルスルホン系誘導体であり、後述の一般式（２）で表されるジフェニルスルホン誘導体（ｂ）又は４,４'−ビス(ハロメチル)ビフェニル、あるいはこれらの混合物と、ジヒドロキシジフェニルスルホン又は後述の一般式（３）で表されるジフェニルスルホン架橋型化合物（ｃ）、あるいはこれらの混合物との脱ハロゲン化水素反応により得ることができる。 [Diphenylsulfone derivative (a)]
The diphenylsulfone derivative (a) represented by the following general formula (1) of the present invention is a compound useful as a developer in a heat-sensitive recording material, and a diphenylsulfone cross-linked compound represented by the general formula (3): This mixture acts particularly effectively as a developer. By using this mixture in a heat-sensitive recording material together with a coloring material composed of a colorless or light leuco dye, the image storage stability can be remarkably improved.

(In the formula, X represents a halogen atom, and n represents an integer of 1 or more.)
The diphenylsulfone derivative (a) represented by the general formula (1) is a diphenylsulfone derivative in which one of the terminal groups is a phenolic hydroxyl group and the other is a halogenated methyl group. 2) diphenylsulfone derivative (b) or 4,4′-bis (halomethyl) biphenyl, or a mixture thereof, and dihydroxydiphenylsulfone or a diphenylsulfone bridged compound represented by the following general formula (3) (C), or a dehydrohalogenation reaction with a mixture thereof.

（式中、Ｙはハロゲン原子を表し、ｐは１以上の整数を表す。）
このジフェニルスルホン誘導体（ｂ）は、特に感熱記録材料における画像安定化剤として有用である。
前記一般式（２）で表されるジフェニルスルホン誘導体（ｂ）の製造方法に特に制限はなく、例えば、ジヒドロキシジフェニルスルホンと４,４'−ビス(ハロメチル)ビフェニル（ハロメチルとしては、クロロメチル又はブロモメチルが好ましい）とを、塩基性物質の存在下、溶媒を用いて脱ハロゲン化水素反応させることにより製造することができる。このとき副生成物として、前記一般式（１）で表されるジフェニルスルホン誘導体（ａ）を生じる場合がある。反応温度としては５０℃以上、溶媒の還流温度以下であることが好ましい。 用いるジヒドロキシジフェニルスルホンとしては、４,４'−ジヒドロキシジフェニルスルホン、２,４'−ジヒドロキシジフェニルスルホン、２,２'−ジヒドロキシジフェニルスルホン、これらの混合物を挙げることができる。 [Diphenylsulfone derivative (b)]
The diphenylsulfone derivative (b) of the present invention is a novel substance and has a structure in which all terminal groups are methyl halide groups as represented by the following general formula (2). It can be adjusted by adjusting the reaction ratio of diphenylsulfone, 4,4′-bis (halomethyl) biphenyl and a basic substance.

(In the formula, Y represents a halogen atom, and p represents an integer of 1 or more.)
This diphenylsulfone derivative (b) is particularly useful as an image stabilizer in heat-sensitive recording materials.
There is no restriction | limiting in particular in the manufacturing method of the diphenyl sulfone derivative (b) represented by the said General formula (2), For example, dihydroxy diphenyl sulfone and 4,4'-bis (halomethyl) biphenyl (Halomethyl is chloromethyl or bromomethyl. Can be produced by dehydrohalogenation using a solvent in the presence of a basic substance. At this time, the diphenyl sulfone derivative (a) represented by the general formula (1) may be produced as a by-product. The reaction temperature is preferably 50 ° C. or higher and the solvent reflux temperature or lower. Examples of the dihydroxydiphenyl sulfone used include 4,4′-dihydroxydiphenyl sulfone, 2,4′-dihydroxydiphenyl sulfone, 2,2′-dihydroxydiphenyl sulfone, and mixtures thereof.

Examples of the basic substance include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, pyridine and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.
On the other hand, as the solvent, ketones such as acetone; nitriles such as acetonitrile; ethers such as tetrahydrofuran; esters such as methyl acetate, dimethyl carbonate and propylene carbonate; N-methylformamide, N, N-dimethylformamide and the like Amides; Sulfoxides such as dimethyl sulfoxide; aromatic hydrocarbons such as toluene, xylene and mesitylene; and mixed solvents thereof.

In the production of the diphenylsulfone derivative (b) represented by the general formula (2), the molar ratio of dihydroxydiphenylsulfone to bis (halomethyl) biphenyl is preferably 1:10 to 8:10.
When the condensation reaction of dihydroxydiphenyl sulfone and 4,4′-bis (halomethyl) biphenyl is carried out in an excess of 4,4′-bis (halomethyl) biphenyl, the reaction mixture contains unreacted 4,4′-bis. (Halomethyl) biphenyl may be mixed, but the mixed unreacted 4,4′-bis (halomethyl) biphenyl can be easily separated and removed from the target diphenylsulfone derivative (b) by purification. .

（式中、ｍは１以上の整数を表す。）
この一般式（３）で表されるジフェニルスルホン架橋型化合物（ｃ）は、ジヒドロキシジフェニルスルホンと４,４'−ビス(ハロメチル)ビフェニル（ハロメチルとしては、クロロメチル又はブロモメチルが好ましい）とを塩基の存在下、溶媒を用いて脱ハロゲン化水素反応させることにより製造することができ、ｍはジヒドロキシジフェニルスルホン、４,４'−ビス(ハロメチル)ビフェニル及び塩基性物質の反応比率を調整することにより、調節することができる。このとき、副生成物として、前記一般式（１）で表されるジフェニルスルホン誘導体（ａ）を生じる場合がある。反応温度としては５０℃以上、溶媒の還流温度以下であることが好ましい。用いるジヒドロキシジフェニルスルホンとしては、４,４'−ジヒドロキシルジフェニルスルホン、２,４'−ジヒドロキシルジフェニルスルホン、２,２'−ジヒドロキシルジフェニルスルホン及びこれらの混合物を挙げることができる。これらの中で、４,４'−ジヒドロキシルジフェニルスルホンは、画像部の保存性、特に耐湿熱性、耐可塑剤性に優れ、さらに未発色部の耐熱性に優れた顕色物質を得ることができるので特に好適に用いることができる。 [Diphenylsulfone cross-linking compound (c)]

(In the formula, m represents an integer of 1 or more.)
The diphenylsulfone bridged compound (c) represented by the general formula (3) comprises dihydroxydiphenylsulfone and 4,4′-bis (halomethyl) biphenyl (halomethyl is preferably chloromethyl or bromomethyl) as a base. In the presence, m can be produced by dehydrohalogenation reaction using a solvent, m is adjusted by adjusting the reaction ratio of dihydroxydiphenylsulfone, 4,4′-bis (halomethyl) biphenyl and a basic substance, Can be adjusted. At this time, the diphenyl sulfone derivative (a) represented by the general formula (1) may be generated as a by-product. The reaction temperature is preferably 50 ° C. or higher and the solvent reflux temperature or lower. Examples of the dihydroxydiphenyl sulfone used include 4,4′-dihydroxyldiphenyl sulfone, 2,4′-dihydroxyldiphenyl sulfone, 2,2′-dihydroxyldiphenyl sulfone, and mixtures thereof. Among these, 4,4′-dihydroxyldiphenylsulfone is capable of obtaining a developer having excellent storage stability of an image area, in particular heat and heat resistance and plasticizer resistance, and excellent heat resistance of an uncolored area. Therefore, it can be used particularly preferably.

Examples of the basic substance include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, pyridine and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.
On the other hand, as solvents, alcohols such as methanol, ethanol, propanol, isopropanol, butanol and isobutanol; glycols such as ethylene glycol, propylene glycol, diethylene glycol and dipropylene glycol; monoalkyl ethers of glycols; glycols Dialkyl ethers; Ketones such as acetone; Nitriles such as acetonitrile; Ethers such as tetrahydrofuran; Esters such as methyl acetate, dimethyl carbonate and propylene carbonate; Amides such as N-methylformamide and N, N-dimethylformamide Sulphoxides such as dimethyl sulphoxide, aromatic hydrocarbons such as toluene, xylene, and mesitylene, and mixed solvents thereof, and the like. A mixed solvent can also be used. As the mixed solvent with water, alcohols and aromatic hydrocarbons are preferable. As the alcohol, isopropanol, ethanol, and methanol are preferable, and ethanol and isopropanol are particularly preferable.

  In the production of the diphenylsulfone bridged compound (c) represented by the general formula (3), the molar ratio of dihydroxydiphenylsulfone to bis (halomethyl) biphenyl is preferably 10: 3 to 10: 8. If the amount of bis (halomethyl) biphenyl with respect to 10 mol of dihydroxydiphenylsulfone is less than 3 mol, the degree of condensation of the resulting cross-linked compound is difficult to increase, and the amount of unreacted dihydroxydiphenylsulfone in the reaction mixture may increase. is there. If the amount of bis (halomethyl) biphenyl with respect to 10 moles of dihydroxydiphenylsulfone exceeds 8 moles, the concentration of terminal hydroxyl groups in the reaction product may decrease.

[Synthesis of Diphenylsulfone Derivative (a)]
As described above, the diphenylsulfone derivative (a) represented by the general formula (1) is a diphenylsulfone derivative in which one of the terminal groups is a phenolic hydroxyl group and the other is a halogenated methyl group. The diphenylsulfone derivative (a) includes the diphenylsulfone derivative (b) represented by the general formula (2) or 4,4′-bis (halomethyl) biphenyl, or a mixture thereof, and dihydroxydiphenylsulfone or the general formula (3). It can obtain by dehydrohalogenation reaction with the diphenyl sulfone bridge | crosslinking type compound represented by these, or a mixture thereof.

  Specifically, first, dihydroxydiphenylsulfone, diphenylsulfone bridged compound (c) or a mixture thereof (hereinafter collectively referred to as a dihydroxyphenyl compound) is dissolved in a solvent and added. Bis (halomethyl) biphenyl (halomethyl is preferably chloromethyl or bromomethyl) or diphenylsulfone derivative (b), or a mixture thereof (hereinafter collectively referred to as dihalomethyl compounds) It can be obtained by adding 0.5 to 0.7 equivalents of a basic substance and further adding a dihalomethyl compound. In this reaction, a part of the phenolic hydroxyl group of the dihydroxyphenyl compound is activated, the dehydrohalogenation reaction proceeds with the dihalomethyl compound, and dehalogenation occurs when the basic substance is consumed in the reaction. The hydrogen reaction is terminated, and the diphenylsulfone derivative (a) represented by the general formula (1) can be obtained.

  In the combination of a dihydroxyphenyl compound and a dihalomethyl compound, when dihydroxydiphenylsulfone is used as the dihydroxyphenyl compound, 4,4′-bis (halomethyl) biphenyl or 4,4′-bis is used as the dihalomethyl compound. It is preferable to use a mixture of (halomethyl) biphenyl and a diphenylsulfone derivative (b). When 4,4′-bis (halomethyl) biphenyl is used as the dihalomethyl compound, dihydroxydiphenylsulfone and diphenyl are used as the dihydroxyphenyl compound. It is preferable to use a mixture with the sulfone crosslinking compound (c). When diphenylsulfone crosslinkable compound (c) is used as the dihydroxyphenyl compound and diphenylsulfone derivative (b) is used as the dihalomethyl compound, the polymerization degree of diphenylsulfone derivative (a) becomes too high depending on the degree of polymerization. The content of phenolic hydroxyl groups in the reaction product may be reduced. Particularly preferred as the combination is a mixture of dihydroxydiphenylsulfone and diphenylsulfone bridged compound (c) as the dihydroxyphenyl compound, and a combination of 4,4′-bis (halomethyl) biphenyl as the dihalomethyl compound.

The reaction temperature for synthesizing the diphenylsulfone derivative (a) of the present invention is preferably 50 ° C. or higher and the reflux temperature of the solvent or lower. Examples of the dihydroxydiphenyl sulfone used include 4,4′-dihydroxyldiphenyl sulfone, 2,4′-dihydroxyldiphenyl sulfone, 2,2′-dihydroxyldiphenyl sulfone, and mixtures thereof. Examples of the basic substance include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, pyridine and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.
On the other hand, as solvents, alcohols such as methanol, ethanol, propanol, isopropanol, butanol and isobutanol; glycols such as ethylene glycol, propylene glycol, diethylene glycol and dipropylene glycol; monoalkyl ethers of glycols; glycols Dialkyl ethers; Ketones such as acetone; Nitriles such as acetonitrile; Ethers such as tetrahydrofuran; Esters such as methyl acetate, dimethyl carbonate and propylene carbonate; Amides such as N-methylformamide and N, N-dimethylformamide Sulphoxides such as dimethyl sulphoxide, aromatic hydrocarbons such as toluene, xylene and mesitylene, and mixed solvents thereof, and the like. Mixed solvent may also be used. As the mixed solvent with water, alcohols and aromatic hydrocarbons are preferable. As the alcohol, isopropanol, ethanol, and methanol are preferable, and ethanol and isopropanol are particularly preferable.

  In the production of the diphenylsulfone derivative (a) represented by the general formula (1), the reaction molar ratio between the dihydroxyphenyl compound and the dihalomethyl compound is preferably 20: 1 to 10: 8. If the reaction molar ratio of the dihalomethyl compound to the dihydroxy compound is lower than the above range, the content of the diphenylsulfone derivative (a) represented by the general formula (1) may be reduced, and the reaction molar ratio exceeds the above range. Then, since the degree of polymerization of the diphenylsulfone derivative (a) represented by the general formula (1) is increased, the content of the phenolic hydroxyl group in the reaction product may be reduced.

[Thermal recording material]
The heat-sensitive recording material of the present invention comprises a heat-sensitive recording developer comprising a diphenylsulfone derivative (a) represented by the general formula (1) and a diphenylsulfone cross-linking compound represented by the general formula (3), and colorless. Or a heat-sensitive color-developing layer containing a color-developing substance composed of a light-colored leuco dye, and a diphenylsulfone derivative represented by the general formula (2) (b) ) As an image stabilizer.

(Coloring substance)
In the present invention, there is no particular limitation on the colorless or light leuco dye used as the color developing material contained in the thermosensitive coloring layer, and examples thereof include fluorane derivatives, quinazoline derivatives, phthalide derivatives, triphenylmethane derivatives, phenothiazine derivatives, and the like. . Among these leuco dyes, fluorane derivatives are particularly suitable because they have good color developability. Examples of leuco dyes that are fluorane derivatives include 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7- (2 ′, 4′-dimethylanilino) fluorane, 3 -Diethylamino-6-methyl-7-chlorofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-diamilamino-6-methyl-7-anilinofluorane, 3- (N-methyl) -N-propyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-butyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N -Amyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-pro L) Amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-amyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isoamyl) Amino-6-methyl-7-anilinofluorane, 3- [N-ethyl-N- (4-methylphenyl)] amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N -Cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- (N-pentyl-N-cyclohexyl) amino-6-methyl-7-anilinofluorane, 3- (N-hexyl-N-isoamyl) Amino-6-methyl-7-anilinofluorane, 3-diethyl-N-butylamino-7- (2′-fluoroanilino) fluorane, 3- (N-methyl-N-cyclohexyl) amino-6 Chlorofluorane, 3-pyrodyryl 7-dibenzylaminofluorane, 3-bis (diphenylamino) fluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3-diethylamino-7- (2′-chloroanilino) fluorane, 3-dibutylamino -7- (2'-chloroanilino) fluorane, 3-diethylamino-7-chlorofluorane, 3-butylamino-7- (2'-chloroanilino) fluorane, 3-diethylamino-6-ethoxyethyl-7-anilinofluor Examples thereof include uranium and 3-diethylamino-7-dibenzylaminofluorane.
These leuco dyes may be used singly or in combination of two or more. The amount of the color developing substance to be contained in the thermosensitive color-developing layer is appropriately determined according to the characteristics of the target thermosensitive recording material. You can choose.

(Developer)
In the present invention, the diphenylsulfone derivative (a) represented by the general formula (1) or the diphenylsulfone derivative (a) and the diphenylsulfone crosslinked compound (c) represented by the general formula (3) The mixture can be used as a developer, and a conventionally known developer can also be used in combination. The diphenylsulfone derivative (a) represented by the general formula (1) used in the present invention, or a mixture of the diphenylsulfone derivative (a) and the diphenylsulfone bridged compound (c) represented by the general formula (3); By using together with a conventionally known developer, it is possible to further improve the storage stability of the image area and the storage stability of the non-color development area without impairing the color developability of the conventionally known developer. Although there is no restriction | limiting in particular in the conventionally well-known developer which can be used, For example, the following are mentioned.

  α-naphthol, β-naphthol, 4-octylphenol, pt-octylphenol, pt-butylphenol, p-phenylphenol, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1- Bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3-phenyl-4) -Hydroxyphenyl) propane, 2,2-bis (3,4-dihydroxyphenyl) propane, 2,2-bis (2,5-dibromo-4-hydroxyphenyl) propane, 2,2-bis (3-t- Butyl-4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) methylpentane, 1,1,3-tri (2-Methyl-4-hydroxy-5-t-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, 1,6-bis (4-hydroxy) Benzoyloxymethyl) hexane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, bis (2-hydroxy-4-chlorophenyl) methane, bis ( 4-hydroxyphenyl) methane, 1,3-bis (4-hydroxycumyl) benzene, 1,4-bis (4-hydroxycumyl) benzene, 1,4-bis (4′-hydroxybenzoyloxymethyl) benzene 1,4-bis (4-hydroxybenzoyloxymethyl) cyclohexane, 1,3-bis (3′-hydroxybenzoyloxymethyl) cyclohexane, 1,2-bis (2′-hydroxy) Droxybenzoyloxy) cyclohexane, α, α-bis (4-hydroxyphenyl) -α-methyltoluene, 4,4′-thiobisphenol, 4,4′-thiobis (2-methylphenol), 4,4′-thiobis (2-chlorophenol), 4,4′-thiobis (6-tert-butyl-2-methylphenol), 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, 1,5 -Bis (4-hydroxyphenylthio) -3-oxapentane, 1,3-bis (4-hydroxyphenylthio) -2-hydroxypropane, 4,4'-diphenol sulfoxide, 4,4'-dihydroxydiphenyl sulfone 2,4′-dihydroxydiphenylsulfone, 3,3′-diallyl-4,4′-dihydroxydiphenylsulfone, 4-allyloxy-4′-hydroxydiphenylsulfone, 4- N-dioxy-4′-hydroxydiphenyl sulfone, 4-isopropoxy-4′-hydroxydiphenyl sulfone, 4-ethoxy-4′-hydroxydiphenyl sulfone, 4-propoxy-4′-hydroxydiphenyl sulfone, 4-methyl-4′- Hydroxydiphenylsulfone, 4-methyl-3 ′, 4′-dihydroxydiphenylsulfone, bis-2,4 (phenylsulfonyl) phenol, 4,4′-dihydroxydiphenylsulfone diethyl ether condensate, 4,4′-bis [( 4-methyl-3-phenoxycarbonylaminophenyl) ureido] diphenylsulfone, N- (p-toluenesulfonyl) -N ′-(3-p-toluenesulfonyloxyphenyl) urea, N- (4′-hydroxyphenylthio) Acetyl-2-hydroxyaniline, N- (4′-hydroxyl Enylthio) acetyl-4-hydroxyaniline, methyl bis (4-hydroxyphenyl) acetate, butyl bis (4-hydroxyphenyl) acetate, benzyl bis (4-hydroxyphenyl) acetate, benzyl p-hydroxybenzoate, p-hydroxybenzoate Ethyl acetate, isopropyl p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, stearyl gallate, lauryl gallate, Octyl gallate, N, N′-diphenylthiourea, N, N′-di (m-chlorophenyl) thiourea, N- (p-toluenesulfonyl) -N ′-(3-p-butoxyphenyl) urea, N -(P-toluenesulfonyl) -N '-(p-butoxyphenyl) urea, N- (p-toluenesulfo Nyl) -N′-phenylurea, 2-hydroxy-3-naphthoic acid, 2-hydroxy-1-naphthoic acid, 1-hydroxy-2-naphthoic acid and the like.

(Sensitizer)
Examples of general sensitizers used in heat-sensitive recording materials include fatty acid amides such as stearamide and palmitic acid amide; 1,2-diphenoxyethane, 1,2-bis (4-methylphenoxy) ethane, 1, 2-bis (3-methylphenoxy) ethane, 1,2-bis (phenoxymethyl) benzene, 1,3-bis (phenoxymethyl) benzene, 1,4-bis (phenoxymethyl) benzene, 1,2-bis ( 3-methylphenoxymethyl) benzene, 1,3-bis (3-methylphenoxymethyl) benzene, 1,4-bis (3-methylphenoxymethyl) benzene, 1,2-bis (4-methylphenoxymethyl) benzene, 1,3-bis (4-methylphenoxymethyl) benzene, 1,4-bis (4-methylphenoxymethyl) benzene, 2-benzyloxynaphthalene, dibenzyl oxalate, Di (4-methylbenzyl) oxalate, di (4-chlorobenzyl) oxalate, 4-acetylbenzyl, N-phenyltoluenesulfonamide, toluenesulfonsannaphthyl, p-benzylbiphenyl, m-terphenyl, 4,4 '-Dipropoxydiphenylsulfone, 4,4'-diisopropoxydiphenylsulfone, 4,4'-diallyloxydiphenylsulfone, 2,4'-dipropoxydiphenylsulfone, 2,4'-diisopropoxydiphenylsulfone, 2 4,4'-diallyloxydiphenylsulfone, benzyl p-benzyloxybenzoate, benzyl terephthalate, and the like.

(Image stabilizer)
In the heat-sensitive recording material of the present invention, the heat-sensitive color developing layer can further contain a diphenylsulfone derivative (b) represented by the general formula (2) as an image stabilizer, and a conventional known image stabilizer can be used. It can also be used together. The image stabilizer that can be used in combination is not particularly limited, and examples thereof include 4-benzyloxy-4 ′-(2-methylglycidyloxy) -diphenylsulfone, 4,4′-diglycidyloxydiphenylsulfone, and 4,4′-. Butylidenebis (3-methyl-6-tert-butylphenol), 2,2′-di-tert-butyl-5,5′-dimethyl-4,4′-sulfonyldiphenol, 1,1,3-tris (2- Compounds having a polyester structure such as methyl-4-hydroxy-5-t-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, polyhydroxybenzoic acid, Examples thereof include substances having a urethane structure such as urea urethane and substances having a polyether structure such as poly (phenylsulfone) ether. These image stabilizers can be used alone or in combination of two or more.

(Fillers, other additives)
In the heat-sensitive recording material of the present invention, a filler can be contained in the heat-sensitive coloring layer as required. Examples of the filler include inorganic fillers such as silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, clay, talc, titanium oxide, aluminum hydroxide, zinc oxide, zinc hydroxide, barium sulfate, and surface-treated silica. And polystyrene microballs, nylon powder, urea-formalin resin filler, silicone resin particles, cellulose powder, styrene / methacrylic acid copolymer particles, vinylidene chloride resin particles, styrene / acrylic copolymer particles, plastic spherical hollow particles, etc. And organic fillers. These fillers can be used individually by 1 type, or can also be used in combination of 2 or more type.

  In the heat-sensitive recording material of the present invention, other additives can be contained in the heat-sensitive color developing layer as necessary. Examples of the additive to be contained include lubricants such as stearic acid ester wax, polyethylene wax and zinc stearate, benzophenone-based ultraviolet absorbers such as 2-hydroxy-4-benzyloxybenzophenone, benzotriazole, and 2- (2 ′ Examples thereof include triazole-based ultraviolet absorbers such as -hydroxy-5'-methylphenyl) benzotriazole, water-proofing agents such as glyoxal, dispersants, antifoaming agents, antioxidants, and fluorescent dyes.

[Manufacture of thermal recording materials]
The method for producing the heat-sensitive recording material of the present invention is not particularly limited. For example, a coloring substance, a developer, and a sensitizer, an image stabilizer, and other components added as necessary, together with an appropriate binder, It can be produced by dispersing in a medium such as an aqueous medium to prepare a coating solution for the thermosensitive coloring layer, coating the coating solution on a support, and drying. The dispersion containing the color former, developer, and sensitizer was prepared separately for each of the dispersion containing the color developer, the dispersion containing the developer, and the dispersion containing the sensitizer. It is preferable to prepare by mixing these dispersions. In each dispersion liquid, it is desirable that the color developing substance, the developer and the sensitizer are finely dispersed, and therefore, it is preferable to use a sand mill, a ball mill or the like for the preparation of these dispersion liquids.
(Binder)
The binder is not particularly limited, and examples thereof include cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, methoxy cellulose, ethyl cellulose, and carboxymethyl cellulose; polyvinyl alcohol, carboxy-modified polyvinyl alcohol, sulfone-modified polyvinyl alcohol, silicone-modified polyvinyl alcohol, and amide-modified polyvinyl. Polyvinyl alcohols such as alcohol; natural polymers such as gelatin, casein, starch and alginic acid; polyacrylic acid, polyacrylic acid ester, polyvinyl acetate, polymethacrylic acid ester, vinyl chloride / vinyl acetate copolymer, ethylene / Vinyl acetate copolymer, vinyl acetate / acrylate copolymer, polyacrylamide, acrylamide / acrylate copolymer, Kurylamide / acrylic acid ester / methacrylic acid terpolymer, isobutylene / maleic anhydride copolymer, styrene / acrylic acid ester copolymer, styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, styrene / Maleic anhydride copolymer, methyl vinyl ether / maleic anhydride copolymer, carboxy-modified polyethylene, polyvinyl alcohol / acrylamide block copolymer, polyvinylpyrrolidone, melamine-formaldehyde resin, urea-formaldehyde resin, polyurethane, polyamide resin, petroleum Examples thereof include resins and terpene resins. These binders can be used individually by 1 type, or can also be used in combination of 2 or more type.

(Support, undercoat layer, backcoat layer)
The support used for the heat-sensitive recording material of the present invention is not particularly limited, and examples thereof include paper such as neutral paper and acid paper, synthetic paper, recycled paper using waste paper pulp, film, nonwoven fabric, woven fabric, and the like. be able to.
In the heat-sensitive recording material of the present invention, on the support, silica, calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, clay, talc, titanium oxide, aluminum hydroxide, zinc oxide, zinc hydroxide, barium sulfate, Surface-treated inorganic fillers such as silica, polystyrene microballs, nylon powder, urea-formalin resin filler, silicone resin particles, cellulose powder, styrene / methacrylic acid copolymer particles, vinylidene chloride resin particles, styrene / acrylic copolymer It is preferable to provide an undercoat layer or a backcoat layer containing organic fillers such as polymer particles and plastic spherical hollow fine particles. By providing an undercoat layer or a backcoat layer, it can act as a heat insulating layer, and can improve sensitivity by efficiently using thermal energy from a thermal head or the like. In particular, an undercoat layer or a backcoat layer containing plastic spherical hollow fine particles can be suitably used because it can effectively improve thermal sensitivity.

In addition, the plastic spherical hollow fine particles are fine hollow particles having a thermoplastic resin as a shell, containing air or other gas inside and already foamed, and an average particle size of about 0.2 to 20 μm. belongs to. When the average particle diameter (particle outer diameter) is smaller than 0.2 μm, there are production problems such as difficult to obtain an arbitrary hollow ratio, which is difficult in terms of cost. Since the surface smoothness after coating and drying is lowered, the adhesion with the thermal head is lowered, and the effect of improving the thermal sensitivity is lowered. Therefore, it is preferable that the particles have a particle size in the above range and have little variation in particle size. Further, the spherical shape of the plastic spherical particles is preferably 40% or more, more preferably 90% or more, considering the heat insulation effect. Those having a low hollowness have insufficient heat insulation effect, so that heat energy from the thermal head is released to the outside of the heat-sensitive recording material through the support, resulting in poor heat sensitivity improvement effect. The “hollow ratio” referred to here is the ratio of the outer diameter to the inner diameter of the hollow fine particles, and is expressed below.
Hollow ratio (%) = [(inner diameter of hollow fine particles) / (outer diameter of hollow fine particles)] × 100
As described above, the plastic spherical hollow fine particles have a thermoplastic resin as a shell. Examples of the resin include polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyacrylate, polyacrylonitrile, and polybutadiene. Or those copolymer resins etc. are mentioned. Among these, a copolymer resin mainly composed of vinylidene chloride and acrylonitrile is particularly preferable.

  There are no particular limitations on the binder used for the undercoat layer and the backcoat layer, for example, cellulose derivatives such as hydroxyethyl cellulose, methyl cellulose, methoxy cellulose, ethyl cellulose, carboxymethyl cellulose; polyvinyl alcohol, carboxy-modified polyvinyl alcohol, sulfone-modified polyvinyl alcohol, Polyvinyl alcohols such as silicone-modified polyvinyl alcohol and amide-modified polyvinyl alcohol; natural polymers such as gelatin, casein, starch and alginic acid; polyacrylic acid, polyacrylic acid ester, polyvinyl acetate, polymethacrylic acid ester, vinyl chloride / Vinyl acetate copolymer, ethylene / vinyl acetate copolymer, vinyl acetate / acrylate copolymer, polyacrylamide, acrylic Mido / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer, isobutylene / maleic anhydride copolymer, styrene / acrylic acid ester copolymer, styrene / butadiene copolymer, styrene / Butadiene / acrylic copolymer, styrene / maleic anhydride copolymer, methyl vinyl ether / maleic anhydride copolymer, carboxy-modified polyethylene, polyvinyl alcohol / acrylamide block copolymer, polyvinyl pyrrolidone, melamine-formaldehyde resin, urea Examples include formaldehyde resin, polyurethane, polyamide resin, petroleum resin, and terpene resin.

In the heat-sensitive recording material of the present invention, if necessary, a water-soluble resin such as a cellulose derivative or polyvinyl alcohol, a water-soluble emulsion such as a styrene-butadiene copolymer or a terpene resin, An overcoat layer can be formed by adding monomers or oligomers such as fillers, isocyanates, unsaturated compounds, and crosslinking agents to water-insoluble resins and those resins.
The heat-sensitive recording material of the present invention can be a multi-color heat-sensitive recording material in which color-forming substances having different color tones are formed in multiple layers as heat-sensitive color forming layers.

EXAMPLES Next, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited at all by these examples.
In the examples, the reactant composition and the compound composition were measured under the following conditions.
(Measurement conditions of gel permeation chromatography (GPC))
Chromatograph: “HLC-8020” manufactured by Tosoh Corporation
Column: Tosoh Co., Ltd., TSK gel G2000H × L + TSK gel G3000H × L
Column temperature: 40 ° C
Moving bed: Dimethylformamide Flow rate: 1.0 ml / min Detector: RI
(Measurement conditions for ¹ H-NMR)
Nuclear magnetic resonance apparatus: “AL-300” manufactured by JEOL Ltd.
Solvent: Heavy dimethyl sulfoxide Internal standard: Tetramethylsilane (DSC measurement conditions)
DSC body: DSC-50 manufactured by Shimadzu Corporation
Temperature rise condition (first run): Room temperature to 250 ° C., 10 ° C./min Temperature drop condition (First run): 250 ° C. to room temperature, 30 ° C./min Temperature rise condition (second run): Room temperature to 250 ° C., 10 ° C./min

In the examples and comparative examples, the performance of the produced thermosensitive recording material was evaluated by the following method.
(1) Oil resistance Using the thermal printing device [manufactured by Okura Electric Co., Ltd.] on the produced thermal recording material, color was developed at a printing voltage of 20 V and a pulse width of 3 ms, and the color density of the colored part (image part) was determined. It was measured using a reflection densitometer [manufactured by Macbeth, “RD-918”]. Next, a drop of cottonseed oil was dropped on the image area and allowed to stand at 20 ° C. and 65% RH for 24 hours, and then the color density was measured.
(2) Plasticizer resistance Using the thermal printing device [manufactured by Okura Electric Co., Ltd.] on the produced thermal recording material, the color was developed at a printing voltage of 20 V and a pulse width of 3 ms, and the color of the colored part (image part) The density was measured using a reflection densitometer [manufactured by Macbeth, “RD-918”]. Next, 3 sheets of polyvinyl chloride wrap and 10 sheets of ordinary paper were stacked on the image area, and the weight was applied so that the density was about 1.96 N / cm ^2, and left at 20 ° C. and 65% RH for 24 hours. Thereafter, the color density was measured.
(3) Heat resistance The color density of an uncolored portion (uncolored portion) of the produced thermosensitive recording material was measured using a reflection densitometer [Macbeth Co., Ltd., “RD-918”]. Next, after standing at 80 ° C. or 100 ° C. for 24 hours, the color density was measured.

ｋ＝０：保持時間 １９.２分：面積％ ２.５
ｋ＝１：保持時間 １７.５分：面積％ ２９.５
ｋ＝２：保持時間 １６.５分：面積％ １９.３
ｋ＝３：保持時間 １５.８分：面積％ １２.７
ｋ≧４：保持時間 １５.３分：面積％ ３５.０ Synthesis Example 1 [Synthesis of diphenylsulfone bridged compound (c)]
In a four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, 100 g of 4,4′-dihydroxydiphenylsulfone [manufactured by Nikka Chemical Co., Ltd., trade name “BPS-P (T)”] and 200 g of isopropanol are placed. , Dissolved. Subsequently, 300 g of an aqueous solution in which 16 g of sodium hydroxide was dissolved was added and heated to 60 ° C., then 50 g of 4,4′-bis (chloromethyl) -1,1′-biphenyl was added, and the mixture was heated under reflux for 3 Stir for hours. Thereafter, 4 g of sodium hydroxide was added, and the mixture was further stirred for 2 hours. The mixture was cooled to 50 ° C., neutralized by adding a diluted hydrochloric acid aqueous solution dropwise, and then heated to distill off isopropanol. The crystals were filtered under reduced pressure at 60 ° C., and the crystals were washed with 100 g of hot water at 60 ° C. 60 g of methanol and 240 g of water were added to the obtained crystals, heated under reflux for 3 hours, cooled to 40 ° C., and the crystals were isolated by filtration under reduced pressure. When dried, 95 g of a white reaction product was obtained.
The second run of DSC measurement had a Tg of 118 ° C. Further, this was measured by gel permeation chromatography [manufactured by Tosoh Corporation] and confirmed to have the following composition.

k = 0: Retention time 19.2 minutes: Area% 2.5
k = 1: Retention time 17.5 minutes: Area% 29.5
k = 2: Retention time 16.5 minutes: Area% 19.3
k = 3: Retention time 15.8 minutes: Area% 12.7
k ≧ 4: Retention time 15.3 minutes: Area% 35.0

（式中、ｋは１以上の整数を表す。）
ｑ＝１ ：保持時間 １８.１分：面積％ １.２
ｑ＝２とｋ＝１の和：保持時間 １７.２分：面積％ ２７.１
ｑ＝３とｋ＝２の和：保持時間 １６.２分：面積％ ２１.８
ｑ＝４とｋ＝３の和：保持時間 １５.５分：面積％ １２.５
ｑ＝５とｋ＝４の和：保持時間 １５.１分：面積％ ９.９
また、¹Ｈ−ＮＭＲ（重ジメチルスルホキシド）での測定結果、５.２ｐｐｍにシングレットピーク（−ＣＨ₂Ｏ−）、４.８ｐｐｍにシングレットピーク（−ＣＨ₂−Ｃｌ）を確認した。それぞれの積分比(−ＣＨ₂Ｏ−)／(−ＣＨ₂−Ｃｌ)は、１０／１であった。 Example 1 [Synthesis of a mixture of a diphenylsulfone derivative (a) and a diphenylsulfone bridged compound (c)]
In a four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, 5 g of 4,4′-dihydroxydiphenylsulfone [manufactured by Nikka Chemical Co., Ltd., trade name “BPS-P (T)”] 100 g of an aqueous solution in which 45 g of the obtained diphenylsulfone cross-linking compound (c), 100 g of isopropanol and 1.6 g of sodium hydroxide were dissolved was added, and the mixture was stirred for 1 hour while heating under reflux. After cooling to 60 ° C., 7.5 g of 4,4′-bis (chloromethyl) -1,1′-biphenyl was added, and the mixture was stirred for 2 hours while heating under reflux. After confirming that the pH of the content liquid became neutral, the solution was filtered under reduced pressure and the crystals were washed with 200 g of hot water at 60 ° C. When dried, a mixture was obtained with a yield of 51 g.
The melting point was 154 ° C. in the first run of DSC measurement. Further, this was measured by gel permeation chromatography [manufactured by Tosoh Corporation] and confirmed to have the following composition.

(In the formula, k represents an integer of 1 or more.)
q = 1: Retention time 18.1 minutes: Area% 1.2
Sum of q = 2 and k = 1: retention time 17.2 minutes: area% 27.1
Sum of q = 3 and k = 2: Retention time 16.2 minutes: Area% 21.8
Sum of q = 4 and k = 3: retention time 15.5 minutes: area% 12.5
Sum of q = 5 and k = 4: retention time 15.1 minutes: area% 9.9
The measurement results of ¹ H-NMR (deuterated dimethyl sulfoxide), singlet peak at 5.2ppm (-CH ₂ O -), was confirmed singlet peaks (-CH ₂ -Cl) to 4.8 ppm. Each integration ratio (—CH ₂ O —) / (— CH ₂ —Cl) was 10/1.

ｒ＝１：保持時間 １７.１分：面積％ ３７.１
ｒ＝２：保持時間 １６.１分：面積％ ２４.０
ｒ＝３：保持時間 １５.５分：面積％ １６.１
ｒ＝４：保持時間 １４.６分：面積％ ９.５
ｒ＞５：保持時間 １５.０分：面積％ １２.８
また、¹Ｈ−ＮＭＲ（重ジメチルスルホキシド）での測定結果、５.２ｐｐｍにシングレットピーク(−ＣＨ₂Ｏ−）、４.８ｐｐｍにシングレットピーク（−ＣＨ₂−Ｃｌ）を確認した。それぞれの積分比(−ＣＨ₂Ｏ−)／(−ＣＨ₂−Ｃｌ)は、４／１であった。 Example 2 [Synthesis of diphenylsulfone derivative (b)]
In a four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, 50 g of 4,4′-dihydroxydiphenylsulfone [manufactured by Nikka Chemical Co., Ltd., trade name “BPS-P (T)”] and 100 g of isopropanol are placed. , Dissolved. Subsequently, 200 g of an aqueous solution in which 8.4 g of sodium hydroxide was dissolved was added and heated to 60 ° C., and then 100 g of 4,4′-bis (chloromethyl) -1,1′-biphenyl was added and heated to reflux. For 2 hours. After confirming that the reaction solution became neutral, the reaction solution was cooled, filtered at 60 ° C. under reduced pressure, and washed with 100 g of methanol. To the obtained crystals, 300 g of methyl ethyl ketone was added and heated under reflux for 1 hour. The crystals were filtered under reduced pressure at 25 ° C. and washed with 50 g of methyl ethyl ketone. Further, 300 g of an aqueous solution containing 50 g of methanol was added to the obtained crystals, heated and stirred at reflux for 1 hour, and then the crystals were filtered under reduced pressure at 50 ° C., washed with 100 g of hot water at 60 ° C. and dried. 85 g was obtained.
The melting point was 167 ° C. in the first run of DSC measurement. Moreover, as a result of measuring this thing by the gel permeation chromatography [made by Tosoh Corporation], it confirmed that it was the following compositions.

r = 1: Retention time 17.1 minutes: Area% 37.1
r = 2: Retention time 16.1 minutes: Area% 24.0
r = 3: retention time 15.5 minutes: area% 16.1
r = 4: retention time 14.6 minutes: area% 9.5
r> 5: retention time 15.0 minutes: area% 12.8
The measurement results of ¹ H-NMR (deuterated dimethyl sulfoxide), singlet peak at 5.2ppm (-CH ₂ O -), was confirmed singlet peaks (-CH ₂ -Cl) to 4.8 ppm. Each integration ratio (—CH ₂ O —) / (— CH ₂ —Cl) was 4/1.

Example 3
By dispersing 10 parts by weight of 3-dibutylamino-6-methyl-7-anilinofluorane, 10 parts by weight of a 10% by weight aqueous polyvinyl alcohol solution and 30 parts by weight of water using a sand mill for 4 hours, A coloring substance dispersion (liquid A) was prepared. The developer dispersion (B) was prepared by finely pulverizing and dispersing 10 parts by mass of the compound obtained in Example 1 and 10 parts by mass of a 10% by weight polyvinyl alcohol aqueous solution and 30 parts by mass of water using a sand mill for 3 hours. Liquid). Silica gel dispersion was achieved by finely pulverizing and dispersing 10 parts by mass of silica gel [manufactured by Mizusawa Chemical Co., Ltd., “P527”], 10 parts by mass of a 10% by weight polyvinyl alcohol aqueous solution and 30 parts by mass of water using a sand mill. A liquid (liquid C) was prepared. A zinc stearate dispersion (liquid D) was prepared by pulverizing and dispersing 10 parts by weight of zinc stearate, 10 parts by weight of a 10% by weight aqueous polyvinyl alcohol solution and 30 parts by weight of water using a sand mill for 3 hours. . Non-foaming plastic micro hollow particles (solid content 24% by mass, average particle size 3 μm, hollowness 90%) 40 parts by mass, styrene / butadiene copolymer latex [manufactured by Nippon Zeon Co., Ltd., “Nipol (registered trademark) LX438C ]] A resin liquid (E liquid) was prepared by stirring and mixing 10 parts by mass and 50 parts by mass of water using a disper.
Next, 5 parts by mass of A liquid, 20 parts by mass of B liquid, 20 parts by mass of C liquid, and 2.5 parts by mass of D liquid were stirred and mixed using a disper to prepare a coating solution for a coloring layer. Moreover, 5 mass parts of C liquid and 10 mass parts of E liquid were stirred and mixed using the disper, and the coating liquid of the undercoat layer was prepared.
The high-quality paper having a basis weight 60 g / m ^2, by coating a coating solution for undercoat layer so as to have a dry coating amount of the 3 g / m ^2, to obtain an undercoat coated paper and dried. On this undercoat layer, the color layer coating solution was applied so that the dry coating amount was 5 g / m ² , dried, and calendered at a pressure of 0.98 MPa to produce a thermal recording paper, and evaluated. went. The results are shown in Table 1.

Example 4
Instead of 10 parts by mass of the reaction product obtained in Example 1, 5 parts by mass of the reaction product obtained in Synthesis Example 1 and 5 parts by mass of the reaction product obtained in Example 1 were used as a developer. A heat-sensitive recording paper was prepared and evaluated in the same manner as in Example 3 except that the dispersion (liquid B) was prepared. The results are shown in Table 1.

Example 5
Instead of 10 parts by mass of the reaction product obtained in Example 1, 7 parts by mass of the reaction product obtained in Synthesis Example 1 and 3 parts by mass of the reaction product obtained in Example 2 were used as a developer. A heat-sensitive recording paper was prepared and evaluated in the same manner as in Example 3 except that the dispersion (liquid B) was prepared. The results are shown in Table 1.

Example 6
Instead of 10 parts by mass of the reaction product obtained in Example 1, 5 parts by mass of the reaction product obtained in Synthesis Example 1, 3 parts by mass of the reaction product obtained in Example 1, and obtained in Example 2 A thermosensitive recording paper was prepared and evaluated in the same manner as in Example 3 except that a developer dispersion (liquid B) was prepared using 2 parts by mass of the obtained reaction product. The results are shown in Table 1.

Comparative Example 1
Instead of the reaction product obtained in Example 1, a polycondensate of 4,4′-dihydroxydiphenylsulfone and bis (2-chloroethyl) ether [manufactured by Nippon Soda Co., Ltd., “D-90”] was used. Then, a thermal recording paper was prepared and evaluated in the same manner as in Example 3 except that the developer dispersion liquid (Liquid B) was prepared. The results are shown in Table 1.

  From the results in Table 1, it is clear that the heat-sensitive recording material using the compound of the present invention as a developer is excellent in image oil resistance, plasticizer resistance and background heat resistance.

  The diphenylsulfone derivative having a phenolic hydroxyl group and a halogenated methyl group as terminal groups of the present invention can be effectively used as a developer having good storage stability, and the diphenylsulfone cross-linking compound in which both terminal groups are phenolic hydroxyl groups It works particularly effectively when used together. In addition, diphenylsulfone derivatives in which both terminal groups are methyl halide groups can be effectively used as an image stabilizer having good storage stability. Since the heat-sensitive recording material using these compounds according to the present invention is excellent in heat-resistant storage stability and water resistance of the image area, for example, in a severe environment where dry heat or wet heat is applied after printing, for example, a microwave heated food label, parking ticket Even when used for a delivery label or the like, the recorded information can be stably held.

Claims (5)

A reaction product of dihydroxydiphenyl sulfone and 4,4′-bis (halomethyl) biphenyl, wherein at least one of the end groups is a halogenated methyl group, represented by the following general formula (1) or (2) Diphenylsulfone derivative represented.

(In the formula, X represents a halogen atom, and n represents an integer of 1 or more.)

(In the formula, Y represents a halogen atom, and p represents an integer of 1 or more.) A mixture of the diphenylsulfone derivative according to claim 1 and a diphenylsulfone cross-linked compound represented by the following general formula (3).

(In the formula, m represents an integer of 1 or more.)   A heat-sensitive recording material comprising a support and a heat-sensitive color-developing layer containing a color-developing substance comprising a colorless or light-colored leuco dye and a color developer, wherein the color developer is represented by the general formula (1). A heat-sensitive recording material comprising a mixture of a diphenylsulfone derivative and a diphenylsulfone cross-linking compound represented by the general formula (3).   A heat-sensitive recording material comprising a support and a heat-sensitive color-developing layer containing a color-developing material comprising a colorless or light-colored leuco dye, a developer and an image stabilizer, wherein A heat-sensitive recording material comprising a diphenylsulfone derivative represented by the formula (2).   A heat-sensitive recording material provided on a support with a heat-sensitive color-developing layer containing a color-developing material comprising a colorless or light-colored leuco dye, a developer and an image stabilizer, wherein the developer is represented by the general formula A mixture of the diphenylsulfone derivative represented by (1) and the diphenylsulfone bridged compound represented by the above general formula (3) is used, and the image stabilizer is represented by the above general formula (2). A heat-sensitive recording material comprising a diphenylsulfone derivative.