JP2010105928A - Diphenyl sulfone cross-link type compound, color-developing substance for heat-sensitive recording and heat-sensitive recording material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sensitive recording material which develops a color in high density, is excellent in the preservability, especially water resistance and plasticizer resistance, of image portions, and is also excellent in the preservability, especially heat resistance, of color-undeveloped portions. <P>SOLUTION: There is provided a heat-sensitive recording material characterized by disposing a heat-sensitive color-developing layer comprising the color-developing substance for the heat-sensitive recording, comprising a diphenylsulfone cross-link type compound represented by general formula (1) and a color-developing substance comprising a colorless or monochromatic leuco dye on a support. Therein, (a) is an integer of 1 to 6; at least one of X groups is a divalent cross-linking group such as 4,4'-bis(methylene)diphenylene; at least one of X groups is a divalent cross-linking group such as xylylene; R<SP>1</SP>to R<SP>6</SP>are each a halogen atom, 1 to 6C alkyl or alkenyl; (m), (n), (p), (q), (r) and (t) are each an integer of 0 to 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel diphenylsulfone cross-linking compound, a thermal recording developer and a thermal recording material. More specifically, the present invention relates to a novel diphenylsulfone crosslinkable compound useful as a developer capable of providing a heat-sensitive recording material excellent in storability of an image area and storability of an uncolored area, from the crosslinkable compound. The present invention relates to a heat-sensitive recording developer and a heat-sensitive recording material comprising the developer and having the above-described excellent properties.

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 color developing component is a lactone, lactam or sultone type non-colored dye base, an organic acid and a heat-fusible substance (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 comprises a support sheet material having a phenolic substance, which 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 (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 (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 (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 develops color at a high concentration, and is excellent in storage stability of an image area, particularly water resistance and plasticizer resistance, and also excellent in storage stability of an uncolored area, particularly heat resistance. It was made for the purpose of providing a heat-sensitive recording material.

［式中、ａは１〜６の整数を表し、Ｘのうちの少なくとも一つは、下記式（Ａ）で表される２価の架橋基であり、Ｘのうちの少なくとも一つは、下記式（Ｂ）若しくは式（Ｃ）で表される２価の基、あるいは炭素数１〜１２のエーテル結合を有してもよい飽和又は不飽和の直鎖状若しくは分岐鎖状の２価の炭化水素基から選ばれる架橋基を表す。ａが２以上の場合、残りのＸは、式（Ａ）、式（Ｂ）若しくは式（Ｃ）で表される２価の基、あるいは炭素数１〜１２のエーテル結合を有してもよい飽和又は不飽和の直鎖状若しくは分岐鎖状の２価の炭化水素基であってもよい。Ｒ¹〜Ｒ⁶はそれぞれに独立にハロゲン原子、炭素数１〜６のアルキル基又はアルケニル基を表し、ｍ、ｎ、ｐ、ｑ、ｒ及びｔはそれぞれ置換基Ｒ¹〜Ｒ⁶の置換基数であり、０〜４の整数を表す。置換基数が２以上の場合、各々の置換基は同一であっても、相異なっていてもよい。］

（式中、Ｒ⁷及びＲ⁸は互いに独立に、メチレン基又はエチレン基を表す。）

（式中、Ｔは水素原子、又は炭素数１〜４のアルキル基を表す。）
［２］一般式（１）において、Ｘが式（Ａ）と式（Ｂ）で表される２価の架橋基である、上記[１]項に記載のジフェニルスルホン架橋型化合物、
［３］式（Ｂ）で表される２価の架橋基におけるＲ⁷及びＲ⁸が共にメチレン基であり、かつ一般式（１）におけるｍ、ｎ、ｐ、ｑ、ｒ及びｔが、いずれも０である、上記[２]項に記載のジフェニルスルホン架橋型化合物、
［４］上記[１]〜[３]項のいずれか１項に記載のジフェニルスルホン架橋型化合物からなる感熱記録用顕色物質、及び
［５］上記[４]項に記載の感熱記録用顕色物質と、無色又は単色のロイコ染料からなる発色物質とを含有する感熱発色層を支持体上に設けてな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 using a diphenylsulfone cross-linking compound having a specific structure as a developer for thermal recording. Based on this finding, the present invention has been completed.
That is, the present invention
[1] A diphenylsulfone crosslinked compound represented by the following general formula (1):

[Wherein, a represents an integer of 1 to 6, at least one of X is a divalent bridging group represented by the following formula (A), and at least one of X represents A divalent group represented by the formula (B) or the formula (C), or a saturated or unsaturated linear or branched divalent carbon which may have an ether bond having 1 to 12 carbon atoms. Represents a crosslinking group selected from hydrogen groups. When a is 2 or more, the remaining X may have a divalent group represented by the formula (A), the formula (B) or the formula (C), or an ether bond having 1 to 12 carbon atoms. It may be a saturated or unsaturated linear or branched divalent hydrocarbon group. R ^{1 to} R ⁶ each independently represents a halogen atom, an alkyl group or an alkenyl group having 1 to 6 carbon atoms, and m, n, p, q, r, and t are the number of substituents of the substituents R ^{1 to} R ⁶ , respectively. And represents an integer of 0 to 4. When the number of substituents is 2 or more, each substituent may be the same or different. ]

(In the formula, R ⁷ and R ⁸ each independently represents a methylene group or an ethylene group.)

(In the formula, T represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)
[2] The diphenylsulfone cross-linking compound according to the above [1], wherein X is a divalent cross-linking group represented by the formula (A) and the formula (B) in the general formula (1),
[3] R ⁷ and R ⁸ in the divalent bridging group represented by the formula (B) are both methylene groups, and m, n, p, q, r and t in the general formula (1) are Diphenylsulfone cross-linking compound according to item [2], wherein 0 is also 0,
[4] A thermal recording developer comprising the diphenylsulfone cross-linking compound according to any one of [1] to [3] above, and [5] a thermal recording developer according to [4] above. A heat-sensitive recording material comprising a support and a heat-sensitive color-developing layer containing a color substance and a color-developing substance composed of a colorless or monochromatic leuco dye;
Is to provide.

  According to the present invention, by using a novel diphenylsulfone cross-linking compound as a color developing material for heat-sensitive recording, the image portion is excellent in storage stability, particularly water resistance and plasticizer resistance. It is possible to provide a heat-sensitive recording material that has excellent storage stability, particularly heat resistance, and can withstand and use severe conditions after printing.

本発明のジフェニルスルホン架橋型化合物は、ジヒドロキシジフェニルスルホンを、以下に示す特定の成分で架橋した構造を有している。
前記一般式（１）において、ａは１〜６の整数を表す。
また、Ｘのうちの少なくとも一つは、下記式（Ａ）で表される２価の架橋基であり、Ｘのうちの少なくとも一つは、下記式（Ｂ）若しくは式（Ｃ）で表される２価の基、あるいは炭素数１〜１２のエーテル結合を有してもよい飽和又は不飽和の直鎖状若しくは分岐鎖状の２価の炭化水素基から選ばれる架橋基を表す。ａが２以上の場合、残りのＸは、式（Ａ）、式（Ｂ）若しくは式（Ｃ）で表される２価の基、あるいは炭素数１〜１２のエーテル結合を有してもよい飽和又は不飽和の直鎖状若しくは分岐鎖状の２価の炭化水素基であってもよく、たがいに異なっていてもよい。
さらに、Ｒ¹〜Ｒ⁶はそれぞれに独立にハロゲン原子、炭素数１〜６のアルキル基又はアルケニル基を表し、ｍ、ｎ、ｐ、ｑ、ｒ及びｔはそれぞれ置換基Ｒ¹〜Ｒ⁶の置換基数であり、０〜４の整数を表す。置換基数が２以上の場合、各々の置換基は同一であっても、たがいに異なっていてもよい。 First, the diphenylsulfone crosslinked compound of the present invention will be described.
[Diphenylsulfone crosslinking compound]
The diphenylsulfone crosslinking compound of the present invention is a novel compound and has a structure represented by the following general formula (1).

The diphenylsulfone crosslinked compound of the present invention has a structure in which dihydroxydiphenylsulfone is crosslinked with the following specific components.
In the said General formula (1), a represents the integer of 1-6.
Further, at least one of X is a divalent bridging group represented by the following formula (A), and at least one of X is represented by the following formula (B) or formula (C). Or a bridging group selected from a saturated or unsaturated linear or branched divalent hydrocarbon group which may have an ether bond having 1 to 12 carbon atoms. When a is 2 or more, the remaining X may have a divalent group represented by the formula (A), the formula (B) or the formula (C), or an ether bond having 1 to 12 carbon atoms. It may be a saturated or unsaturated linear or branched divalent hydrocarbon group, and may be different.
R ^{1 to} R ⁶ each independently represent a halogen atom, an alkyl group having 1 to 6 carbon atoms or an alkenyl group, and m, n, p, q, r, and t are each a substituent of R ^{1 to} R ⁶ . It is the number of substituents and represents an integer of 0 to 4. When the number of substituents is 2 or more, each substituent may be the same or different.

（式中、Ｒ⁷及びＲ⁸は互いに独立に、メチレン基又はエチレン基を表す。）

（式中、Ｔは水素原子、又は炭素数１〜４のアルキル基を表す。）
前記一般式（１）で示される本発明のジフェニルスルホン架橋型化合物は、ジヒドロキシジフェニルスルホンと、特定の構造を有するジハロゲン化物との重縮合反応によって得ることができる。
本発明のジフェニルスルホン架橋型化合物において、式（Ａ）に示す２価の架橋基は本発明の必須構成成分であり、前記ジハロゲン化物としては４,４'−ビス(ハロメチル)ビフェニルを用いることがでる。
式（Ｂ）で示される２価の架橋基からなる構成成分において、Ｒ⁷及びＲ⁸はメチレン基、又はエチレン基である。式（Ｂ）に示す構成成分を有するジハロゲン化物として、キシリレンハライド、ジエチルベンゼンハライド、メチルエチルベンゼンハライドを挙げることができるが、末端ヒドロキシ基の含有率低下を最小限に留めるためには、Ｒ⁷及びＲ⁸が共にメチレン基であるキシリレンハライドを用いることが特に好ましい。
また、式（Ｃ）で示される２価の架橋基からなる構成成分において、Ｔは水素原子、又は炭素数１〜４のアルキル基を表す。式（Ｃ）に示す２価の構成成分を有するジハロゲン化物としてはジクロロヒドリン、ジクロロメチルプロパノールなどを例示できるが、末端ヒドロキシ基の含有率低下を最小限に留めるためには、Ｔが水素原子であるジクロロヒドリンを用いるのが好ましい。

(In the formula, R ⁷ and R ⁸ each independently represents a methylene group or an ethylene group.)

(In the formula, T represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)
The diphenylsulfone bridged compound of the present invention represented by the general formula (1) can be obtained by a polycondensation reaction between dihydroxydiphenylsulfone and a dihalide having a specific structure.
In the diphenylsulfone crosslinking type compound of the present invention, the divalent crosslinking group represented by the formula (A) is an essential component of the present invention, and 4,4′-bis (halomethyl) biphenyl is used as the dihalide. Out.
In the component composed of a divalent crosslinking group represented by the formula (B), R ⁷ and R ⁸ are a methylene group or an ethylene group. Examples of the dihalide having the component represented by the formula (B) include xylylene halide, diethylbenzene halide, and methylethylbenzene halide. In order to minimize the decrease in the content of terminal hydroxy groups, R ⁷ and It is particularly preferable to use a xylylene halide in which both R ⁸ are methylene groups.
Moreover, in the structural component which consists of a bivalent bridge | crosslinking group shown by Formula (C), T represents a hydrogen atom or a C1-C4 alkyl group. Examples of the dihalide having a divalent component represented by the formula (C) include dichlorohydrin and dichloromethylpropanol. In order to minimize the decrease in the content of the terminal hydroxy group, T is a hydrogen atom. It is preferable to use dichlorohydrin which is

The saturated or unsaturated linear or branched divalent hydrocarbon group which may have an ether bond having 1 to 12 carbon atoms is a saturated hydrocarbon having 1 to 12 carbon atoms having an ether bond. The group is preferably exemplified, and CH ₂ CH ₂ OCH ₂ CH ₂ that can be introduced when dichloroethyl ether is used as the dihalide is particularly preferable.
R ^{1 to} R ⁶ each independently represents a halogen atom, an alkyl group having 1 to 6 carbon atoms or an alkenyl group, and preferably an alkyl group having 1 to 3 carbon atoms. Also, m, n, p, q , r and t are each the number of substituents the substituents R ¹ to R ^6, represents an integer of 0-4. When the number of substituents is 2 or more, each substituent may be the same or different, but when m, n, p, q, r, and t are all 0, the terminal hydroxy group This is most preferable because the decrease in content can be minimized.

The diphenylsulfone cross-linking compound of the present invention has a rigid molecular skeleton because it is cross-linked with a 4,4′-bis (methylene) biphenylene group represented by the formula (A) in the molecular main chain as an essential component. The transition point is increased and the heat resistance is improved. Furthermore, by introducing the xylylene group represented by the formula (B) into the molecular chain, the oil resistance and plasticizer resistance of the diphenylsulfone crosslinked compound are improved. The xylylene group has isomers of o-, m-, and p-, among which o- and m-isomers are preferable.
The diphenylsulfone cross-linking compound of the present invention is particularly useful as a developer in a heat sensitive recording material.

(Synthesis of diphenylsulfone bridged compound of general formula (1))
The diphenylsulfone bridged compound represented by the general formula (1) of the present invention includes dihydroxydiphenylsulfone, a dihalide having a divalent group represented by the formula (A), and the formula (B) or the formula (C). Or a dihalide having a saturated or unsaturated linear or branched divalent hydrocarbon group which may have an ether bond having 1 to 12 carbon atoms. It is obtained by reacting a seed, and in each molecular chain, a divalent group represented by formula (A) and a divalent group represented by formula (B) or formula (C), or The saturated or unsaturated linear or branched divalent hydrocarbon group which may have an ether bond having 1 to 12 carbon atoms is reliably introduced with at least one divalent group. To achieve this, it is synthesized via a two-stage polycondensation reaction It is desirable.

In the first stage, dihydroxydiphenyl sulfone and a dihalide having a divalent group represented by the formula (A) [specifically, 4,4′-bis (halomethyl) biphenyl (halomethyl is preferably chloromethyl or bromomethyl)] ] Is dehydrohalogenated in the presence of a base and a solvent to produce a polycondensate represented by the following general formula (2). 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. Among these, 4,4′-dihydroxydiphenyl sulfone can provide a color developing material excellent in storage stability of an image area, particularly moisture and heat resistance and plasticizer resistance, and also excellent in heat resistance of an uncolored area. Therefore, it can be particularly preferably used. Regarding the molecular weight distribution of the polycondensate represented by the general formula (2), the sum of b = 1 and b = 2 is preferably 50% or more by mass ratio.

  In the second stage polycondensation reaction, first, the polycondensate represented by the general formula (2) obtained in the first stage and a divalent group represented by the formula (B) or the formula (C), Alternatively, at least one dihalide having a saturated or unsaturated linear or branched divalent hydrocarbon group which may have an ether bond having 1 to 12 carbon atoms is used as a basic substance and a solvent. Reacts in the presence. Thereby, the components of the dihalide added for the second-stage reaction between the polycondensates represented by the general formula (2) are cross-linked, and the diphenylsulfone cross-linked compound represented by the general formula (1) Can be obtained. The compound obtained here is a compound in which the components that crosslink diphenylsulfone at both ends are the crosslinking components used in the first-stage reaction. In addition, the polycondensate represented by the general formula (2) obtained in the first stage, the divalent group represented by the formula (B) or the formula (C), or the ether bond having 1 to 12 carbon atoms After reacting with at least one kind of dihalide having a saturated or unsaturated linear or branched divalent hydrocarbon group which may have a basic substance and a solvent, dihydroxydiphenyl By adding a sulfone, in addition to the above compound, the component that crosslinks diphenylsulfone at both ends is the crosslinking component used in the second stage, and has the first stage crosslinking component in the middle, The terminal polycondensate represented by the general formula (2), that is, the terminal diphenyl sulfone is cross-linked with the cross-linking component used in the first stage, and the other end uses diphenyl sulfone in the second stage. Cross-linking Compounds crosslinked min is produced. The reaction temperature is preferably 50 ° C. or higher and the solvent reflux temperature or lower.

Examples of the basic substance used in the first stage and the second stage 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.
Solvents used include 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; dialkyls of glycols 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; Examples thereof include sulfoxides such as dimethyl sulfoxide, aromatic hydrocarbons such as toluene, xylene, and mesitylene, and mixed solvents thereof. A mixed solvent can also be used. As the mixed solvent with water, alcohols and aromatic hydrocarbons are preferable.

The present invention also provides a color developer for thermal recording comprising the diphenylsulfone crosslinking type compound represented by the general formula (1).
Next, the heat-sensitive recording material of the present invention will be described.
[Thermal recording material]
The heat-sensitive recording material of the present invention comprises a heat-sensitive color developing layer comprising a heat-sensitive recording developer composed of a diphenylsulfone cross-linked compound represented by the general formula (1) and a color developing material composed of a colorless or light leuco dye. Is provided on a support.
(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 crosslinking compound represented by the general formula (1) can be used alone as a developer, but can also be used in combination with a conventionally known developer. By using the diphenylsulfone crosslinking type compound represented by the general formula (1) used in the present invention in combination with a conventionally known developer, an image can be obtained without impairing the color developability of the conventionally known developer. It is possible to further improve the storage stability of the part and the storage stability of the non-colored part. 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)
In the heat-sensitive recording material of the present invention, a sensitizer can be further contained in the heat-sensitive coloring layer. Examples of the sensitizer 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-methyl) Benzyl), 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'-diallyloxydiphenyl Examples include sulfone, benzyl p-benzyloxybenzoate, and benzyl terephthalate. These sensitizers may be used individually by 1 type, and may be used in combination of 2 or more type.

(Image stabilizer)
In the heat-sensitive recording material of the present invention, an image stabilizer can be further contained in the heat-sensitive coloring layer. The image stabilizer used is not particularly limited, and examples thereof include 4-benzyloxy-4 ′-(2-methylglycidyloxy) -diphenylsulfone, 4,4′-diglycidyloxydiphenylsulfone, 4,4′-butylidenebis ( 3-methyl-6-tert-butylphenol), 2,2′-di-tert-butyl-5,5′-dimethyl-4,4′-sulfonyldiphenol, 1,1,3-tris (2-methyl- 4-hydroxy-5-t-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane, compounds having a polyester structure such as polyhydroxybenzoic acid, urea urethane Examples thereof include a substance having a urethane structure such as a substance 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 used 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 include triazole-based ultraviolet absorbers such as -hydroxy-5'-methylphenyl) benzotriazole, water resistance agents such as glyoxal, dispersants, antifoaming agents, antioxidants, and fluorescent dyes.

(Manufacture of thermal recording materials)
There is no particular limitation on the method for producing the heat-sensitive recording material of the present invention, for example, a coloring substance, a developer, and a sensitizer, an image stabilizer, and other components to be 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. A dispersion containing a color former, a developer, and a sensitizer is prepared separately for each of a dispersion containing a color former, a dispersion containing a developer, and a dispersion containing a sensitizer. It is preferable to prepare by mixing these dispersions. In each dispersion liquid, it is desirable that the color developing substance, the color developing substance, and the sensitizer are dispersed in fine particles. Therefore, it is preferable to use a sand mill, a ball mill, or the like for the preparation of these dispersion liquids.

<Binder>
There are no particular limitations on the binder used, 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, silicone modified polyvinyl alcohol, amide modified Polyvinyl alcohols such as 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 / acrylic acid ester copolymer, polyacrylamide, acrylamide / 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-formaldehyde resin, polyurethane, polyamide resin, A petroleum resin, a terpene resin, etc. can be mentioned. 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 insulating 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 demonstrates this invention 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: manufactured by Tosoh Corporation, TSK gel G2000H × L + TSK gel G3000H × L
Column temperature: 40 ° C
Moving bed: Dimethylformamide Flow rate: 1.0 mL / min Detector: RI
<DSC measurement conditions>
DSC main unit: Shimadzu "DSC-50"
Temperature rise condition (first run): Room temperature to 300 ° C., 10 ° C./min Temperature drop condition (First run): 300 ° C. to room temperature, 30 ° C./min Temperature rise condition (second run): Room temperature to 300 ° C., 10 ° C./min <Measurement conditions of high performance liquid chromatography (HPLC)>
Column: ODS
Dissolving solution: 50% by mass acetonitrile water Column temperature: 40 ° C.
Flow rate: 1 mL / min Injection volume: 5 μL
Detector: UV (254 nm)

In the examples and comparative examples, the performance of the produced thermosensitive recording material was evaluated by the following method.
(1) Plasticizer 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 of the colored part (image part) The density is measured using a reflection densitometer [manufactured by Macbeth, “RD-918”]. Next, 3 sheets of PVC wrap and 10 sheets of general paper are stacked on the image area, and the weight is applied so that the density is about 1.96 N / cm ^2. Was measured.
(2) Water 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 is measured using a reflection densitometer [Macbeth, “RD-918”]. Next, it was immersed in distilled water at 20 ° C. for 24 hours and then air-dried for 3 hours to measure the color density.
(3) Heat resistance The color density of a non-colored portion (uncolored portion) of the produced heat-sensitive recording material is measured using a reflection densitometer [Macbeth, “RD-918”]. Next, after leaving at 80 ° C. or 100 ° C. for 24 hours, the color density was measured.

ａ＝０：ピーク面積比０.３％、ａ＝１：ピーク面積比８６.４％、ａ＝２：ピーク面積比５.４％、ａ＝３：ピーク面積比４.７％、ａ＝４：ピーク面積比３.２％であった。この化合物の平均分子量は７８１である。 Synthesis example 1
In a four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, 4,4′-dihydroxydiphenylsulfone [manufactured by Nikka Chemical Co., Ltd., trade name “BPS-P (T)”] 100 g (0.4 mol) And 500 g of an aqueous solution in which 24 g (0.6 mol) of sodium hydroxide was dissolved, and the mixture was dissolved by heating to 60 ° C. with stirring, and then 200 g of toluene and 4,4′-bis (chloromethyl) -1,1′- 51 g (0.2 mol) of biphenyl was added, and the mixture was stirred for 10 hours while heating under reflux (87 ° C.). Then, after cooling to 80 ° C., a dilute hydrochloric acid aqueous solution was added dropwise for neutralization, followed by filtration under reduced pressure. The crystals were washed with 100 g of hot water at 60 ° C. and dried. Subsequently, 250 g of the obtained crystal and methanol were added to a four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, and the mixture was heated to reflux for 3 hours, cooled to 40 ° C., and the crystal was isolated by vacuum filtration. . When dried, 72 g of a white reaction product was obtained. Tg (glass transition point) of the obtained reaction product was 105 ° C. (DSC measurement: second run). Further, this reaction composition was measured by gel permeation chromatography [manufactured by Tosoh Corporation] and confirmed to have the following composition.

a = 0: Peak area ratio 0.3%, a = 1: Peak area ratio 86.4%, a = 2: Peak area ratio 5.4%, a = 3: Peak area ratio 4.7%, a = 4: The peak area ratio was 3.2%. The average molecular weight of this compound is 781.

ａ＝０：５.３％、ａ＝１：５２.４％、ａ＝２：１９.５％、ａ＝３：１２.６％、ａ＝４：４.８％、ａ＝５：１.９％ Example 1
In a four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, 50 g (0.064 mol) of the reaction product obtained in Synthesis Example 1, 200 g of dimethylformamide, and 2.0 g (0.05) of sodium hydroxide were added. Mol) and heated to 90 ° C. to dissolve. Next, a solution prepared by dissolving 7.0 g (0.04 mol) of α, α′-dichloro-o-xylene in 50 g of dimethylformamide was added dropwise over 0.5 hours. After completion of dropping, the mixture was heated to 110 ° C. and 30 minutes later, disappearance of α, α′-dichloro-o-xylene was confirmed by gel permeation chromatography [manufactured by Tosoh Corporation]. Further, 15 g (0.06 mol) of 4,4′-dihydroxydiphenylsulfone [manufactured by Nikka Chemical Co., Ltd., trade name “BPS-P (T)”] and 4.0 g (0.10 mol) of sodium hydroxide were added to dimethylformamide. A solution dissolved in 100 g was added over 15 minutes and reacted at 120 ° C. for 5 hours. After completion of the reaction, the reaction product was gradually added to 2000 g of a 0.1% by mass hydrochloric acid aqueous solution at 30 ° C. over 0.5 hour, and further stirred for 2 hours. The precipitated crystals were separated by filtration and washed with water. Next, the crystals obtained in a reaction vessel and 500 g of a 50% by mass aqueous methanol solution were charged and stirred at 75 ° C. for 3 hours. The crystals were filtered off at 40 ° C., washed with water and dried to obtain 61 g of a reaction product. . The obtained reaction product had a Tg (glass transition point) of 114 ° C. (DSC measurement: second run). Analysis by gel permeation chromatography [manufactured by Tosoh Corporation] revealed the following composition in area%.

a = 0: 5.3%, a = 1: 52.4%, a = 2: 19.5%, a = 3: 12.6%, a = 4: 4.8%, a = 5: 1 .9%

Example 2
Examples were used except that 7.0 g (0.04 mol) of α, α′-dichloro-m-xylene was used instead of 7.0 g (0.04 mol) of α, α′-dichloro-o-xylene. In the same manner as in Example 1, 50 g of a reaction product was obtained. Tg (glass transition point) of the obtained reaction product was 112 ° C. (DSC measurement: second run). When analyzed by gel permeation chromatography [manufactured by Tosoh Corporation], the area% was as follows.
a = 0: 10.8%, a = 1: 40.3%, a = 2: 23.1%, a = 3: 14.3%, a = 4: 7.6%, a = 5: 2 .6%

Example 3
Example 1 was repeated except that 5.7 g (0.04 mol) of bis (2-chloroethyl) ether was used instead of 7.0 g (0.04 mol) of α, α'-dichloro-o-xylene. As a result, 48 g of a reaction product was obtained. The Tg (glass transition point) of the obtained reaction product was 86 ° C. (DSC measurement: second run). When analyzed by gel permeation chromatography [manufactured by Tosoh Corporation], the area% was as follows.
a = 0: 9.6%, a = 1: 39.2%, a = 2: 23.8%, a = 3: 15.2%, a = 4: 7.8%, a = 5: 3 .1%

Example 4
In a four-necked flask equipped with a stirrer, a reflux condenser, and a thermometer, 50 g (0.064 mol) of the reaction product obtained in Synthesis Example 1, 200 g of dimethylformamide, and 6.4 g of sodium hydroxide (0.16). Mol) and heated to 90 ° C. to dissolve. Next, a solution prepared by dissolving 3.5 g (0.02 mol) of α, α′-dichloro-o-xylene in 40 g of dimethylformamide was added dropwise over 0.5 hours. After completion of the dropwise addition, the mixture was heated to 110 ° C. and 30 minutes later, disappearance of α, α′-dichloro-o-xylene was confirmed by gel permeation chromatography [manufactured by Tosoh Corporation], and further reacted for 5 hours. After completion of the reaction, the reaction product was gradually added to 2000 g of a 0.1% by mass hydrochloric acid aqueous solution at 30 ° C. over 0.5 hour, and further stirred for 2 hours. The precipitated crystals were separated by filtration and washed with water. When dried, 48 g of reaction product was obtained. The obtained reaction product had a Tg (glass transition point) of 114 ° C. (DSC measurement: second run). Analysis by gel permeation chromatography [manufactured by Tosoh Corporation] revealed the following composition in area%.
a = 0: 34.9%, a = 1: 10.4%, a = 2: 38.7%, a = 3: 8.6%, a = 4: 4.2%, a = 5: 1 .8%

Example 5
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. A developer dispersion (B) was prepared by finely pulverizing and dispersing 10 parts by weight of the compound obtained in Example 1 and 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. Liquid). Silica gel dispersion 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 aqueous polyvinyl alcohol 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) LY438C ]] 10 parts by mass and 50 parts by mass of water were stirred and mixed using a disper to prepare a resin liquid (E liquid). 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 developing layer coating solution is applied so that the dry coating amount of the leuco paint is 5 g / m ² , dried and calendered at a pressure of 1 MPa to produce the heat-sensitive recording material of the present invention. And evaluated.

Example 6
Heat sensitive in the same manner as in Example 5 except that the developer dispersion (Liquid B) was prepared using the reaction product obtained in Example 2 instead of the reaction product obtained in Example 1. Recording paper was prepared and evaluated.

Example 7
Heat sensitive in the same manner as in Example 5 except that the developer dispersion (Liquid B) was prepared using the reaction product obtained in Example 3 instead of the reaction product obtained in Example 1. Recording paper was prepared and evaluated.

Example 8
Instead of 10 parts by mass of the reaction product obtained in Example 1, 7 parts by mass of the reaction product obtained in Example 1 and 4-allyloxy-4′-hydroxydiphenylsulfone [manufactured by Nikka Chemical Co., Ltd., “BPS-MAE”] A thermal recording paper was prepared and evaluated in the same manner as in Example 5 except that 3 parts by mass of the developer dispersion (B liquid) was prepared. The composition of the used BPS-MAE was confirmed by high performance liquid chromatography (HPLC). As a result, 4-allyloxy-4′-hydroxydiphenylsulfone was 97.3%, and 4,4′-dihydroxydiphenylsulfone was 0.8. %, 4,4'-diallyloxy-diphenylsulfone, 0.7%, 3-allyl-4-allyloxy-4'-hydroxydiphenylsulfone, 0.5%, 3-allyl-4-hydroxy-4'-allyloxy They were 0.3% diphenylsulfone and 0.3% 3-allyl-4,4′-dihydroxydiphenylsulfone.

Example 9
Instead of 10 parts by mass of the reaction product obtained in Example 1, 7 parts by mass of the reaction product obtained in Example 1, 4-allyloxy-4′-hydroxydiphenylsulfone [manufactured by Nikka Chemical Co., Ltd., The developer dispersion using 2.5 parts by mass of “BPS-MAE” and 0.5 part by mass of 4,4′-diallyloxydiphenylsulfone [manufactured by Nikka Chemical Co., Ltd., “BPS-DAE”] A thermal recording paper was prepared and evaluated in the same manner as in Example 5 except that (Liquid B) was prepared.

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 5 except that the developer dispersion (liquid B) was prepared.
The evaluation results of the heat-sensitive recording materials of Examples 5 to 9 and Comparative Example 1 are shown in Table 1.

  As can be seen in Table 1, the thermal recording materials of Examples 5 to 9 using the diphenylsulfone cross-linking compound of the present invention as a developer compared to the thermal recording material of Comparative Example 1 are resistant to the image area. It is clear that the plasticizer property, water resistance and heat resistance of the uncolored portion are excellent.

  The heat-sensitive recording material of the present invention is excellent in storage stability of the image area, particularly water resistance and plasticizer resistance by using the diphenylsulfone cross-linking compound of the present invention as a color developing material for heat-sensitive recording. In addition to excellent storage stability, particularly heat resistance of the color-developing part, it can withstand severe conditions after printing.

Claims (5)

A diphenylsulfone cross-linking compound represented by the following general formula (1):

[Wherein, a represents an integer of 1 to 6, at least one of X is a divalent bridging group represented by the following formula (A), and at least one of X represents A divalent group represented by the formula (B) or the formula (C), or a saturated or unsaturated linear or branched divalent carbon which may have an ether bond having 1 to 12 carbon atoms. Represents a crosslinking group selected from hydrogen groups. When a is 2 or more, the remaining X may have a divalent group represented by the formula (A), the formula (B) or the formula (C), or an ether bond having 1 to 12 carbon atoms. It may be a saturated or unsaturated linear or branched divalent hydrocarbon group. R ^{1 to} R ⁶ each independently represents a halogen atom, an alkyl group or an alkenyl group having 1 to 6 carbon atoms, and m, n, p, q, r, and t are the number of substituents of the substituents R ^{1 to} R ⁶ , respectively. And represents an integer of 0 to 4. When the number of substituents is 2 or more, each substituent may be the same or different. ]

(In the formula, R ⁷ and R ⁸ each independently represents a methylene group or an ethylene group.)

(In the formula, T represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)   The diphenyl sulfone cross-linking compound according to claim 1, wherein in general formula (1), X is a divalent cross-linking group represented by formula (A) and formula (B). R ⁷ and R ⁸ in the divalent bridging group represented by the formula (B) are both methylene groups, and m, n, p, q, r and t in the general formula (1) are all 0. The diphenylsulfone cross-linking compound according to claim 2, wherein   A developer for heat-sensitive recording, comprising the diphenylsulfone crosslinking compound according to any one of claims 1 to 3.   A heat-sensitive recording material, comprising a heat-sensitive color-developing material according to claim 4 and a color-developing material comprising a colorless or monochromatic leuco dye on a support.