JP2007090828A - Developer for thermal recording material, its manufacturing method, and thermal recording material, thermal recording medium using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer for a thermal recording material excellent in color developing sensitivity, water resistance, oil resistance, and light resistance, a manufacturing method of the same, a thermal recording material containing the developer for the thermal recording material, and the thermal recording medium using the same. <P>SOLUTION: The thermal recording material contains a developer shown by a general formula [1] and a leuco dye. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developer for a thermal recording material, a method for producing the same, a thermal recording material containing the developer for the thermal recording material, and a thermal recording material using the thermal recording material.

  Thermal recording materials are mainly used in facsimiles, measuring devices, medical devices, and the like, and recently, they are used in bar code labels and register receipts used in POS systems and the like, and the amount of use is increasing. With the wide variety of applications, various properties such as water resistance, oil resistance, and light resistance are required for thermal recording materials.

  The heat-sensitive recording material is generally produced by applying a heat-sensitive recording material containing a leuco dye as a color forming precursor and a developer as an acidic compound as basic components on a support. As the developer, a phenol compound has been used for a long time, and a bisphenol compound represented by bisphenol A is most commonly used (for example, see Patent Documents 1 and 2). However, bisphenol A has recently been reported as an environmental hormone substance that adversely affects reproductive function, and the demand for an alternative compound has increased greatly.

  In order to solve this problem, acidic compounds having various phenol skeletons have been studied. However, a color developer in place of bisphenol A having excellent water resistance, oil resistance, and light resistance has not yet been obtained. Is the current situation.

JP-A-56-015394 JP-A-57-151394

  The present invention relates to a developer for a heat-sensitive recording material excellent in color development sensitivity, water resistance, oil resistance, and light resistance, equivalent to or better than that using bisphenol A as a raw material, and a method for producing the same, and the heat-sensitive recording material The present invention provides a heat-sensitive recording material containing a developer and a heat-sensitive recording material using the same.

前記一般式［１］中、Ｒ_１は水素、炭素数１〜４のアルキル基、炭素数５〜７のシクロアルキル基、置換又は無置換フェニル基、置換又は無置換アラルキル基、アルコキシ基、およびハロゲン原子から選ばれるものである。ｎは１〜４の整数を示し、ｎが２〜４のとき、１分子内に存在するＲ_１同士は同じであっても異なっていてもよい。Ｒ_２は水素、水酸基、炭素数１〜４のアルキル基、炭素数５〜７のシクロアルキル基、置換または無置換フェニル基、置換または無置換アラルキル基、アルコキシ基、およびハロゲン原子から選ばれるものである。ｍは１〜４の整数を示し、ｍが２〜４のとき、１分子内に存在するＲ_２同士は同じであっても異なっていてもよい。
Ｒ_３は、エトキシエチル基、フラニル基、ピラニル基、及び、ｔｅｒｔ-ブチルカルボニル基から選ばれるものであり、１種類であっても２種類以上であってもよい。
（２）前記一般式［１］で示される化合物において、Ｒ_１が水素、水酸基、およびメチル基から選ばれるものであり、ｎ＝１〜３である（１）に記載の感熱記録材料用顕色剤。
（３）前記一般式［１］で示される化合物において、Ｒ_２が水素、水酸基、およびメチル基から選ばれるものであり、ｍ＝１〜３である（１）又は（２）に記載の感熱記録材料用顕色剤。
（４）感熱記録材料用顕色剤の製造方法であって、
（ａ）テトラヒドロチオピラン化合物と、フェノール化合物とを、酸性触媒の存在下で反応させて、下記一般式［２］で示されるテトラヒドロチオピラニリデンビスフェノール化合物を合成する工程、及び、
（ｂ）前記テトラヒドロチオピラニリデンビスフェノール化合物と、エチルビニルエーテル、２，３−ジヒドロフラン、３，４−ジヒドロ−２Ｈ−ピラン、及び、ジ−ｔｅｒｔ−ブチルジカルボネイトから選ばれる化合物とを反応させて、下記一般式［１］で示される化合物を合成する工程、
を有することを特徴とする、感熱記録材料用顕色剤の製造方法。

（５）（１）ないし（３）のいずれかに記載の感熱記録材料用顕色剤と、ロイコ染料とを含有することを特徴とする感熱記録材料。
（６）（５）に記載の感熱記録材料を支持体に形成してなることを特徴とする感熱記録材。 (1) A developer for a heat-sensitive recording material comprising a compound represented by the following general formula [1].

In the general formula [1], R ₁ is hydrogen, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, an alkoxy group, and It is selected from halogen atoms. n represents an integer of 1 to 4, and when n is 2 to 4, R ₁ existing in one molecule may be the same or different. R ₂ is selected from hydrogen, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, an alkoxy group, and a halogen atom It is. m represents an integer of 1 to 4, and when m is 2 to 4, R ₂ existing in one molecule may be the same or different.
R ₃ is selected from an ethoxyethyl group, a furanyl group, a pyranyl group, and a tert-butylcarbonyl group, and may be one type or two or more types.
(2) In the compound represented by the general formula [1], R ₁ is selected from hydrogen, a hydroxyl group, and a methyl group, and n = 1 to 3; Coloring agent.
(3) In the compound represented by the general formula [1], R ₂ is selected from hydrogen, a hydroxyl group, and a methyl group, and m is 1 to 3, and heat sensitivity according to (1) or (2) Developer for recording materials.
(4) A method for producing a developer for a heat-sensitive recording material,
(A) a step of synthesizing a tetrahydrothiopyranylidene bisphenol compound represented by the following general formula [2] by reacting a tetrahydrothiopyran compound and a phenol compound in the presence of an acidic catalyst; and
(B) reacting the tetrahydrothiopyranylidene bisphenol compound with a compound selected from ethyl vinyl ether, 2,3-dihydrofuran, 3,4-dihydro-2H-pyran, and di-tert-butyl dicarbonate. A step of synthesizing a compound represented by the following general formula [1],
A method for producing a developer for a heat-sensitive recording material, comprising:

(5) A heat-sensitive recording material comprising the developer for a heat-sensitive recording material according to any one of (1) to (3) and a leuco dye.
(6) A heat-sensitive recording material comprising the heat-sensitive recording material according to (5) formed on a support.

  The present invention relates to a developer for a thermal recording material (hereinafter sometimes simply referred to as “developer”) comprising the compound represented by the above general formula [1], a production method thereof, and a developer for this thermal recording material. A heat-sensitive recording material containing a colorant and a heat-sensitive recording material using the same. According to the present invention, bisphenol A is used without using bisphenol A, which has been pointed out as an environmental problem, as a raw material. A heat-sensitive recording material having color development sensitivity, water resistance, oil resistance, and light resistance equal to or higher than that can be obtained.

Hereinafter, the developer for the heat-sensitive recording material of the present invention, the production method thereof, the heat-sensitive recording material containing the developer for the heat-sensitive recording material, and the heat-sensitive recording material using the same will be described.
First, the developer for the heat-sensitive recording material of the present invention will be described.

上記一般式［１］中、Ｒ_１は水素、炭素数１〜４のアルキル基、炭素数５〜７のシクロアルキル基、置換又は無置換フェニル基、置換又は無置換アラルキル基、アルコキシ基、およびハロゲン原子から選ばれるものである。
ここで、炭素数１〜４のアルキル基としては、例えば、メチル基、エチル基、ｎ−プロピル基、イソプロピル基、ｎ−ブチル基、イソブチル基、ｓｅｃ-ブチル基、ｔｅｒｔ−ブチル基などが挙げられる。
置換又は無置換フェニル基としては、例えば、フェニル基、トルイル基、キシリル基、トリメチルフェニル基などが挙げられる。
置換又は無置換アラルキル基としては、例えば、ベンジル基などが挙げられる。
アルコキシ基としては、例えば、メトキシ基、エトキシ基などが挙げられる。
また、ハロゲン原子としては、フッ素原子、塩素原子、臭素原子、ヨウ素原子が挙げられる。 The developer for a heat-sensitive recording material of the present invention comprises a compound represented by the following general formula [1].

In the general formula [1], R ₁ is hydrogen, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, an alkoxy group, and It is selected from halogen atoms.
Here, examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. It is done.
Examples of the substituted or unsubstituted phenyl group include a phenyl group, a toluyl group, a xylyl group, and a trimethylphenyl group.
Examples of the substituted or unsubstituted aralkyl group include a benzyl group.
Examples of the alkoxy group include a methoxy group and an ethoxy group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In the general formula [1], n represents an integer of 1 to 4, and when n is 2 to 4, R ₁ existing in one molecule may be the same or different. By adjusting the value of n, the melting point of the resulting compound can be controlled.

In the compound represented by the general formula [1], R ₁ is preferably selected from hydrogen, a hydroxyl group, and a methyl group. Thereby, the compound represented by the general formula [1] can have a high melting point.
N is preferably 1 to 3. By appropriately selecting the number of n from this range, it is possible to obtain a melting point suitable for use as a developer, and to further improve storage stability (water resistance and oil resistance).

In the general formula [1], R ₂ is hydrogen, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, or an alkoxy group. And a halogen atom.
Here, examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. It is done.
Examples of the substituted or unsubstituted phenyl group include a phenyl group, a toluyl group, a xylyl group, and a trimethylphenyl group.
Examples of the substituted or unsubstituted aralkyl group include a benzyl group.
Examples of the alkoxy group include a methoxy group and an ethoxy group.
Moreover, as a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned, for example.

In the general formula [1], m represents an integer of 1 to 4, and when m is 2 to 4, R ₂ existing in one molecule may be the same or different. By adjusting the value of m, the melting point of the resulting compound can be controlled.

In the compound represented by the general formula [1], R ₂ is preferably selected from hydrogen, a hydroxyl group, and a methyl group. Thereby, the compound represented by the general formula [1] can have a high melting point.
Moreover, it is preferable that m is 1-3. By appropriately selecting the number m from this range, it is possible to obtain a melting point suitable for use as a developer, and to improve the storage stability (water resistance and oil resistance).

In the compound represented by the general formula [1], R ₃ is selected from an ethoxyethyl group, a furanyl group, a pyranyl group, and a tert-butylcarbonyl group. It may be. Thereby, it can be set as a constitution suitable for using the compound represented by the general formula [1] as a developer, and storage stability (humidity resistance, light resistance) can be improved.

In normal use as a developer, it is desirable to include about 1 to 0.4 and 0.7 to about 0.3 to 0.6 when the total developer is 1. By doing so, it is possible to maintain a good balance between color developability and storage stability when used as a developer.
Alternatively, in particular, when a pyranyl group or t-butylcarbonyl group is used for R ₃ , the melting point can be maintained when used as a developer, and both color developability and storage stability can be achieved.

Next, a method for producing the developer for the heat-sensitive recording material of the present invention (hereinafter sometimes simply referred to as “manufacturing method”) will be described.
The production method of the present invention is a method for producing the above-described developer of the present invention, and has the following steps (a) and (b).
First, step (a) will be described.
In the step (a), a tetrahydrothiopyran compound represented by the following general formula [3] and a phenol compound represented by the following general formula [4] are reacted in the presence of an acidic catalyst to thereby react the general formula [2]. A tetrahydrothiopyranylidene bisphenol compound represented by the following formula is synthesized.

In the general formula [3], R ₁ is hydrogen, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, an alkoxy group, and Are selected from halogen atoms. Examples of these R ₁ may be the same as those described in the general formula [1], but are preferably selected from hydrogen, a methyl group, and an isopropyl group.
Further, n represents an integer of 1 to 4, when n is 2 to 4, R ₁ together present in one molecule may be different even in the same. n is preferably 1 to 3.
As tetrahydrothiopyrans represented by the general formula [3], for example, tetrahydrothiopyran-4-one can be preferably used.
In the general formula [4], R ₂ is hydrogen, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, or an alkoxy group. And a halogen atom. Examples of these R ₂ may be the same as those described in the general formula [1], but are preferably selected from hydrogen, a hydroxyl group, and a methyl group.
M represents an integer of 1 to 4, and when m is 2 to 4, R ₂ existing in one molecule may be the same or different. m is preferably 1 to 3.

  As phenols used for the phenol compound represented by the general formula [4], for example, phenol, cresol, xylenol, resorcin, pyrogallol and the like can be suitably used.

  In the step (a), a reaction solvent may be used as necessary. The reaction solvent is not particularly limited, and any tetrahydrothiopyran compound and phenol compound as raw materials can be dissolved, and any solvent that does not contribute to the present reaction can be used without particular limitation.

  In the step (a), the reaction molar ratio when the tetrahydrothiopyran compound (H) represented by the general formula [3] is reacted with the phenol compound (P) represented by the general formula [4] Although not particularly limited, the reaction molar ratio (H / P) is preferably 0.125 to 0.5. More preferably, it is 0.25-0.4. As a reaction procedure, a phenol compound and an acidic catalyst are charged and mixed. The tetrahydrothiopyran compound is sequentially added thereto. Although reaction temperature is not specifically limited, About room temperature-about 80 degreeC is preferable. The time for sequential addition is not particularly limited, but 0.5 to 3 hours are preferable from the viewpoint of reaction control, reaction rate, and purity of the target compound. The reaction is then carried out for 1-8 hours. As a result, the intended reaction can be performed efficiently and at the same time economic efficiency can be achieved.

Next, step (b) will be described.
In the step (b), the tetrahydrothiopyranylidene bisphenol compound obtained in the step (a), ethyl vinyl ether, 2,3-dihydrofuran, 3,4-dihydro-2H-pyran, and di-tert- A compound selected from butyl dicarbonate is reacted to synthesize a compound represented by the above general formula [1].

The step (b) can be usually performed in the presence of a catalyst.
Among these, when a tetrahydrothiopyranylidene bisphenol compound is reacted with one selected from ethyl vinyl ether, 2,3-dihydrofuran, and 3,4-dihydro-2H-pyran, an acidic catalyst is used. Can do.
Although it does not specifically limit as an acidic catalyst used here, For example, organic carboxylic acids, such as oxalic acid, an acetic acid, trifluoroacetic acid, inorganic acids, such as hydrochloric acid and a sulfuric acid, paratoluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, etc. Organic sulfonic acids, organic phosphonic acids, or heteropolyacids such as phosphomolybdic acid, silicomolybdic acid, phosphotungstic acid, and silicotungstic acid can be used. Among these, hydrochloric acid is preferably used because it is highly reactive and easily available.
Although the usage-amount of an acidic catalyst is not specifically limited, It is preferable to use 0.1 times equivalent or more with respect to the phenols used from the point of reaction control and reaction rate.

Moreover, when making a tetrahydrothio pyranilidene bisphenol compound react with di-tert-butyl dicarbonate, it can carry out using a basic catalyst.
Although it does not specifically limit as a basic catalyst used here, For example, organic bases, such as inorganic bases, such as sodium hydroxide, lithium hydroxide, and potassium hydroxide, ammonia, a triethylamine, a triethanolamine, etc. can be used.

In the step (b), the tetrahydrothiopyranylidene bisphenol compound is dissolved in a solvent, and a predetermined amount of catalyst is added.
When reacting a compound selected from ethyl vinyl ether, 2,3-dihydrofuran, 3,4-dihydro-2H-pyran, and di-tert-butyl dicarbonate, the reaction molar ratio of the two is not particularly limited. The above-mentioned compounds can be 0.3 to 1.0 times equivalent to 1 equivalent of hydroxyl group of the tetrahydrothiopyranylidene bisphenol compound.
The reaction temperature is not particularly limited, but some have a very low boiling point. Therefore, it is desirable that the reaction temperature is about room temperature to about 50 ° C. so as not to greatly exceed the boiling point. Thereafter, the reaction is carried out for 1 to 6 hours. The product obtained by the reaction is placed in a large amount of water together with the reaction solvent to precipitate the target compound. Furthermore, the target compound can be obtained by drying this.
As a result, the intended reaction can be efficiently performed and at the same time economic efficiency can be achieved.

  The thus-obtained compound represented by the general formula [1] can be appropriately subjected to various purification operations such as crystallization, filtration and recrystallization by a usual method. Thereby, a compound with few impurities can be obtained.

Next, the heat-sensitive recording material of the present invention will be described.
The heat-sensitive recording material of the present invention is characterized by containing the developer of the present invention and a leuco dye.

  The leuco dye used in the heat-sensitive recording material of the present invention is not particularly limited. For example, triphenylmethane, fluorane, phenothiazine, auramine, and spiro leuco dyes can be used.

  Examples of triphenylmethane-based leuco dyes include triphenylmethane.

  Examples of the fluorane leuco dye include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone, CVL), p, p'-benzylidenebis (N, N '-Dimethylaniline (leucomalachite green), 3-diethylamino-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3- (N-methyl-p-toluidino)- 6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (N-methylcyclohexyl-N -Methylamino) -6-methyl-7-anilinofluorane, 2-anilino-3-methyl-6-dibutylfluorane, 3 Diethylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-7- (m-trifluoromethylanilino) fluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-6-methylflurane Oran, 3-cyclohexylamino-6-chlorofluorane, 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluorane, and the like.

  Examples of phenothiazine-based leuco dyes include benzoyl leucomethylene blue and p-nitrobenzoyl leucomethylene blue.

  Examples of the olamine leuco dye include 4,4′-bis (dimethylaminophenyl) benzhydrylbenzyl ether, N-chlorophenyl leucoolamine, N-2,4,5-trichlorophenyl leucoolamine. Etc.

  Examples of spiro leuco dyes include 3-methylspirodinaphthopyrans, 3-ethylspirodinaphthopyrans, benzo-β-naphthopiropyrans, and the like.

  These leuco dyes can be appropriately selected depending on the hue and color developability, and can be used alone or as a mixture of two or more as required.

  In addition to the above-mentioned developer and leuco dye, various additives can be added to the heat-sensitive recording material of the present invention as necessary. Examples of the additive mainly include a binder, a pigment, and a sensitizer.

  The binder is not particularly limited. For example, polyvinyl alcohol, starch, starch derivatives, hydroxyethyl cellulose, methyl cellulose, sodium polyacrylate, polyvinyl pyrrolidone, styrene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, etc. An aqueous emulsion such as a water-soluble polymer, styrene-butadiene latex, styrene-acrylic ester emulsion, or polyvinyl acetate emulsion can be added, whereby the developer composition can be strongly adhered to the support.

  The pigment is not particularly limited, and examples thereof include calcium carbonate, talc, kaolin, calcined kaolin, and aluminum hydroxide.

  The sensitizer is not particularly limited, and examples thereof include stearic acid amide, palmitic acid amide, oleic acid amide, lauric acid amide, ethylene bisstearamide, methylol stearoamide, and the like.

  In addition, generally known waxes, wax-like substances, organic fillers, inorganic fillers, and the like can be added to improve head matching properties, writing properties, whitening of the background, and the like.

  In the heat-sensitive recording material of the present invention, the content of the developer of the present invention, the leuco dye, etc. is not particularly limited. Usually, the developer is 1 to 30 weights with respect to the entire solid content in the heat-sensitive recording material. %, Leuco dye 1 to 15% by weight, and binder 1 to 30% by weight.

The method for preparing the heat-sensitive recording material of the present invention is not particularly limited. For example, in addition to a developer containing a compound represented by the above general formula [1], a leuco dye, and an additive such as a binder, It can be prepared as a solution dissolved in or a mixed solution dispersed. When preparing in such a form, this can be normally apply | coated and used for a support body.
In addition, for example, a leuco dye can be mixed with a binder solution, and a developer can be mixed with the binder solution. When using in such a form, the method of applying each mixed solution to the support after mixing the mixed solutions, the method of applying each mixed solution to the same surface of the same support sequentially, or the same mixed solution There is a method of coating the front and back surfaces of the support separately, and the method is not particularly limited.

Next, the heat-sensitive recording material of the present invention will be described.
The heat-sensitive recording material of the present invention is obtained by forming the heat-sensitive recording material of the present invention on a support.
Although it does not specifically limit as a support body here, Generally paper, a synthetic paper, a synthetic resin film, a metal laminate film, etc. can be used. The support can be selected in a timely manner depending on the application and purpose for which the thermosensitive recording material is used. The heat-sensitive recording material of the present invention is obtained by applying the heat-sensitive recording material of the present invention to these supports by, for example, the above-mentioned method, performing a smoothing treatment or the like as necessary, and drying it. It is what

  Hereinafter, the present invention will be described in detail with reference to examples. Here, “parts” all represent “parts by weight”, and “%” all represent “% by weight”. ’

・ Preparation of developer for heat-sensitive recording materials (Synthesis of 4,4'-tetrahydrothiopyranylidene bisphenol compound)
<Example 1>
37.6 parts of phenol (P) and 33.1 parts of 35% hydrochloric acid were added to a reaction vessel equipped with a stirrer, a condenser, a heating device, and a thermometer, and heated to 60 ° C. Thereto, 11.6 parts of tetrahydrothiopyran-4-one (H) was slowly added and allowed to react for 12 hours while maintaining 60 ° C., whereby crystals were precipitated. The hydrochloric acid used for the reaction was neutralized by adding 50.8 parts of 25% aqueous sodium hydroxide solution, washed with hot water to remove as much unreacted monomer as possible, and then dried in a vacuum at 120 ° C. using a dryer. To give 24.3 parts of 4,4′-tetrahydrothiopyranylidenebisphenol.
The obtained crystal was white and had a melting point of 210 ° C. and a target tetrahydrothiopyranylidenephenol compound represented by the above general formula [2] by 98% by DSC measurement.

<Example 2>
100 parts of the 4,4′-tetrahydrothiopyranylidene bisphenol compound obtained in Example 1 was dissolved in 200 parts of acetone, 31.3 parts of 3,4 dihydro-2H-pyran (equivalent ratio 1.0) were added, Further, 0.1 part of paratoluenesulfonic acid was added and reacted at 50 ° C. for 3 hours. After the reaction, the reaction mixture was neutralized by adding triethylamine, and then washed with water.
As a result of analyzing the obtained tetrahydrothiopyranylidene bisphenol reaction product using reverse phase chromatography, 32% of the product obtained in Example 1 (unreacted product) was found in the compound obtained in Example 1. 51% reacted on only one side of the hydroxyl group and 17% reacted on both hydroxyl groups.
To this reaction solution, 100 parts of toluene and 100 parts of a 10% aqueous sodium hydroxide solution were added, and the compound reacted with both of the hydroxyl groups was extracted to the toluene side, and the extract was removed. Further, 100 parts of isopropyl ether was added, and the reaction product was extracted to the ether side to remove unreacted products. The ether content was removed from the ether extract to obtain 35 parts of a compound that reacted only with the target hydroxyl group on one side.

<Example 3>
In a reaction vessel equipped with a stirrer, a condenser, a heating device, and a thermometer, 100 parts of 4,4′-tetrahydrothiopyranylidene bisphenol obtained in Example 1 was dissolved in 200 parts of acetone, and di-tert-butyl was dissolved. Dicarbonate 81.1 parts (equivalent ratio 1.0) was added, and 41.5 parts of triethylamine was further added, and the mixture was reacted at 60 ° C. for 6 hours. After the reaction, 24.6 parts of acetic acid was added for neutralization, followed by washing with water.
As a result of analyzing the obtained tetrahydrothiopyranylidene bisphenol reaction product by using reverse phase chromatography, 50% of the product obtained in Example 1 (unreacted product) was obtained. 46% reacted on only one side of the hydroxyl group and 4% reacted on both hydroxyl groups.
To this reaction solution, 100 parts of toluene and 100 parts of a 10% aqueous sodium hydroxide solution were added, and the compound reacted with both of the hydroxyl groups was extracted to the toluene side, and the extract was removed. Further, 100 parts of isopropyl ether was added, and the reaction product was extracted to the ether side to remove unreacted products. The ether content was removed from the ether extract to obtain 39 parts of a compound that reacted only with the target hydroxyl group on one side.

2. Preparation of thermosensitive recording material <Example 11>
The following raw materials and blends were separately wet-ground with a ball mill for 24 hours to prepare dispersion liquid mixture A and liquid B.

(2.1) Liquid A, crystal violet lactone 10 parts, stearamide 20 parts, 10 wt% polyvinyl alcohol aqueous solution (“# 105” manufactured by Kuraray Co., Ltd.) 60 parts, calcium carbonate 50 parts, water 150 parts

(2.2) Liquid B: 10 parts of the compound obtained in Example 1 · 10% by weight aqueous polyvinyl alcohol solution (“# 105” manufactured by Kuraray Co., Ltd.) 20 parts · Calcium carbonate 20 parts · Water 50 parts

The liquid A and liquid B obtained above were mixed at the following ratio to prepare a heat-sensitive recording material.
(2.3) Thermosensitive recording material / A liquid 20 parts / B liquid 20 parts / 10 wt% polyvinyl alcohol aqueous solution (“# 105” manufactured by Kuraray) 15 parts

<Example 12>
In Example 11, a thermosensitive recording material was obtained in the same manner as in Example 11 except that the compound obtained in Example 2 was used instead of the compound obtained in Example 1.

<Example 13>
In Example 11, a thermosensitive recording material was obtained in the same manner as in Example 11 except that the compound obtained in Example 3 was used instead of the compound obtained in Example 1.

<Comparative example>
In Example 11, a heat-sensitive recording material was obtained in the same manner as in Example 11 except that bisphenol A was used in place of the compound obtained in Example 1.

3. Preparation of heat-sensitive recording material The heat-sensitive recording materials obtained in Examples 11 to 13 and the comparative example were coated on fine paper and dried so that the coating amount after drying was 7 to 9 g / m ^2. Was made.

4). Evaluation of characteristics of heat-sensitive recording materials The items described in Table 1 were evaluated for the heat-sensitive recording materials obtained above. Table 1 shows the evaluation results obtained in Examples 11 to 13 and the comparative example.

(Measurement and evaluation methods)
(1) Content (%) of the compound represented by the general formula [1]:
About the tetrahydrothiopyranylidene bisphenol compound obtained in Examples 2 and 3, the content of the compound represented by the general formula [1] was measured using reverse phase chromatography. Here, “content of the compound represented by the general formula [1]” is obtained by reverse phase chromatography, and both the unreacted product, the compound represented by the general formula [1], and the phenolic hydroxyl group reacted. It is the content calculated from the area ratio corresponding to each of the compounds.
The measurement conditions of reverse phase chromatography are as follows. When measured under these conditions, the retention time of the compound represented by the general formula [1] is about 8 to 9 minutes.
・ Column: manufactured by TOSOH ・ “TSK-GEL ODS-120T”
-Column temperature: 40 ° C
-Mobile phase: THF / water = 7/3 (volume ratio)
・ Flow rate: 0.5 ml / min,
・ Detection wavelength 280nm

(2) Color developability: Two glass plates with a thickness of 1.2 mm were placed on a 200 ° C. heating plate and heated to this temperature. Next, the heat-sensitive recording material obtained above was sandwiched between the glass plates and held for 3 seconds to develop color. This was observed with the naked eye, and the color that was the same color as in the comparative example was marked as ◯.

(3) Water resistance: A colored thermal recording material sample was prepared in the same manner as in the evaluation of color development. This was immersed in pure water at 25 ° C. for 2 hours and then air-dried, and changes in the color image were observed with the naked eye. A sample in which no decrease in density was observed was marked with ◎, and a sample in which a slight decrease in density was observed was marked with ○.

(4) Oil resistance: A colored thermal recording material sample was prepared in the same manner as in the evaluation of color development. This was sandwiched between PVC wrap films and allowed to stand at 40 ° C. for 24 hours under a load of 200 g / cm ² from the upper side of the color development surface, and the change in the color development image was observed with the naked eye. A sample in which no decrease in density was observed was marked with ◎, and a sample in which a slight decrease in density was observed was marked with ○.

(5) Light resistance: A heat-sensitive recording material sample was developed in the same manner as in the evaluation of color development. This was irradiated with ultraviolet rays for 24 hours with an ultraviolet fade meter (FAL-5 manufactured by Suga Test Instruments Co., Ltd.), and the change in the color image was observed with the naked eye. The case where almost no fading or discoloration was observed was marked with ◎, and the case where discoloration or fading was slightly recognized was marked with ◯.

Examples 1 and 2 are the developers for the heat-sensitive recording material of the present invention represented by the general formula [1]. Examples 11 and 12 are the heat-sensitive recording materials of the present invention using these, and in any of water resistance, oil resistance, and light resistance as compared with the comparative example in which the developer composed of bisphenol A is blended. Thus, a heat-sensitive recording material having equivalent or better characteristics could be obtained.

Claims (6)

A developer for heat-sensitive recording material, comprising a compound represented by the following general formula [1].

In the general formula [1], R ₁ is hydrogen, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, an alkoxy group, and It is selected from halogen atoms. n represents an integer of 1 to 4, and when n is 2 to 4, R ₁ existing in one molecule may be the same or different. R ₂ is selected from hydrogen, a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, an alkoxy group, and a halogen atom It is. m represents an integer of 1 to 4, and when m is 2 to 4, R ₂ existing in one molecule may be the same or different.
R ₃ is selected from an ethoxyethyl group, a furanyl group, a pyranyl group, and a tert-butylcarbonyl group, and may be one type or two or more types. 2. The developer for a heat-sensitive recording material according to claim 1, wherein in the compound represented by the general formula [1], R ₁ is selected from hydrogen, a hydroxyl group, and a methyl group, and n = 1-3. In the compound represented by the general formula [1], R ₂ is selected from hydrogen, a hydroxyl group, and a methyl group, and m is 1 to 3, and the developer for the heat-sensitive recording material according to claim 1 or 2. Agent. A method for producing a developer for a heat-sensitive recording material, comprising:
(A) a step of reacting a tetrahydrothiopyran compound and a phenol compound in the presence of an acidic catalyst to synthesize a tetrahydrothiopyranylidene bisphenol compound represented by the following general formula [2], and
(B) reacting the tetrahydrothiopyranylidenebisphenol compound with a compound selected from ethyl vinyl ether, 2,3-dihydrofuran, 3,4-dihydro-2H-pyran, and di-tert-butyl dicarbonate. A step of synthesizing a compound represented by the following general formula [1],
A method for producing a developer for a heat-sensitive recording material, comprising:

A thermosensitive recording material comprising the developer for a thermosensitive recording material according to any one of claims 1 to 3 and a leuco dye. A heat-sensitive recording material comprising the heat-sensitive recording material according to claim 5 formed on a support.