JP2005246703A - New zinc complex and new oxo zirconium complex and thermosensitive recording material including them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new zinc complex and a new oxo zirconium complex and to provide a thermosensitive recording material excellent in conserving characteristics by utilizing them. <P>SOLUTION: The thermosensitive recording material is obtained by utilizing a metal complex synthesized from a specifically structured carboxylic acid and a zinc (II) salt or an oxyzirconium (IV) salt. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a novel zinc complex and oxozirconium complex useful as a color developer for thermal recording.

  The heat-sensitive recording material is provided with a heat-sensitive recording layer mainly composed of an electron-donating colorless or light-colored dye precursor and an electron-accepting developer on a support, and includes a thermal head, a thermal pen, By heating with a laser beam or the like, the dye precursor and the developer react instantaneously to obtain a recorded image. (For example, see Patent Document 1 and Patent Document 2)

  Such a heat-sensitive recording material has advantages such as being able to record with a relatively simple device, being easy to maintain and generating less noise, measuring recorder, facsimile, printer, computer terminal, It is used in a wide range of fields, such as vending machines for labels and tickets. Conventional heat-sensitive recording materials using an electron-donating colorless dye precursor and an electron-accepting developer had characteristics such as a high color density, but on the other hand, when the recording image area was in contact with plastic There are disadvantages in that the storage characteristics of recorded images are inferior, such as plasticizers and additives contained in the plastic permeate and decolorize and contact with chemicals contained in food and cosmetics. Further, when writing on the uncolored portion with a writing tool, there is a drawback that the writing mark is discolored, and these improvements have been strongly desired.

  Means for improving the storage characteristics of the recorded image area and the non-image area include, as an electron-accepting developer, a salicylic acid derivative having a substituent such as an alkyl group, an aralkyl group, an alkyloxy group, an acyl group, or a metal salt thereof. Thermal recording materials to be used have been proposed. (For example, see Patent Document 3, Patent Document 4, and Patent Document 5)

However, the salicylic acid derivatives of known materials still have insufficient storage characteristics of the color image and the non-image area, and the color density is low, making it difficult to call a practical heat-sensitive recording material.
Japanese Patent Publication No.43-4160 Japanese Examined Patent Publication No. 45-14039 JP 62-169681 A JP 63-22683 A JP-A 63-95977

  An object of the present invention is to provide a novel zinc complex and an oxyzirconium complex, and to provide a heat-sensitive recording material excellent in thermal response and image storage stability using the same.

  As a result of researches to solve this problem, the present inventor has obtained a carboxylic acid represented by the following general formula [I] or the following general formula [II] and a divalent zinc salt or a tetravalent oxozirconium halide. By reacting, novel zinc complexes and oxyzirconium complexes useful as color developers for heat-sensitive recording materials were synthesized.

In general formula [I], R ₁ and R ₂ represent a hydrogen atom or an alkyl group, R ₃ and R ₄ represent an alkyl group, and Ar ₁ represents an aryl group having a phenolic hydroxyl group as a substituent. L represents an alkylene group having 1 to 12 carbon atoms.

一般式[II]中、Ａｒ₂はフェノール性水酸基を置換基として有するアリール基あるいはアラルキル基を表し、R₅、R₆は水素原子あるいはアルキル基を、R₇、R₈はアルキル基を表す。Ｑは二価の芳香族炭化水素残基を表す。

In the general formula [II], Ar ₂ represents an aryl group or aralkyl group having a phenolic hydroxyl group as a substituent, R ₅ and R ₆ represent a hydrogen atom or an alkyl group, and R ₇ and R ₈ represent an alkyl group. Q represents a divalent aromatic hydrocarbon residue.

  An electron accepting color of a metal complex synthesized from the carboxylic acid represented by the general formula [I] or the following general formula [II] and a divalent zinc salt or tetravalent oxozirconium halide shown in the present invention. By using as an agent, it is possible to provide a heat-sensitive recording material excellent in both thermal response and image storage stability.

  Specific examples of the compound represented by the general formula [I] include the following, but the present invention is not limited thereto.

  Specific examples of the compound represented by the general formula [II] include the following, for example, but the present invention is not limited thereto.

  The metal complex of the present invention can be synthesized by reacting these compounds with a divalent zinc salt or a tetravalent oxozirconium halide in an aqueous solution in the presence of a base. The resulting metal complex can be isolated as colorless crystals by general solvent removal such as filtration.

  When the metal complex of the present invention is used as an electron-accepting developer, it is possible to obtain a heat-sensitive recording material excellent in storage characteristics of color images, storage stability of non-image areas, and color sensitivity. The detailed reason why the color image is stable is completely unknown, but the following estimation can be made from the experimental facts. In the dye colored body of the recorded image, the metal complex of the present invention and the colored dye maintain a chemically very stable association state, so that when the chemical is contacted with an organic solvent, a plasticizer of plastic, etc. However, the color former is not decomposed, and high storage stability of the color image is achieved.

  Next, although the specific manufacturing method of the thermosensitive recording material using the metal complex of this invention is described, this invention is not limited to this.

  The electron donating dye precursor used in the heat-sensitive recording material of the present invention is not particularly limited as long as it is generally used for pressure-sensitive recording paper and heat-sensitive recording paper. A specific example is as follows.

  (1) Triarylmethane compounds: 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3 -(P-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3 -Bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylaminophthalide, 3,3 -Bis (9-ethitucarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5-dimethylaminophthalide, -p- dimethylaminophenyl-3- (1-methylpyrrole-2-yl) -6-dimethylaminophthalide and the like.

  (2) Diphenylmethane compounds: 4,4′-bis (dimethylaminophenyl) benzhydrylbenzyl ether, N-chlorophenyl leucooramine, N-2,4,5-trichlorophenyl leucooramine and the like.

  (3) Xanthene compounds: Rhodamine B anilinolactam, rhodamine Bp-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-7-octylaminofluorane, 3-diethylamino- 7-phenylfluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-chloro-7-methylfluorane, 3-diethylamino-7- (3,4-dichloroanilino) fluorane, 3-diethylamino -7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3-dipentylamino-6-methyl- 7-anilinofluorane, 3- (N-ethyl-N-tolyl) amino -6-methyl-7-anilinofluorane, 3-diethylamino-7- (4-nitroanilino) fluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3- (N-methyl-N- Propyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane, 3- (N-methyl-N-cyclohexyl) Amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfuryl) amino-6-methyl-7-anilinofluorane, and the like.

  (4) Thiadiazine compounds: benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue, and the like.

  (5) Spiro compounds: 3-methylspirodinaphthopyrans, 3-ethylspirodinaphthopyrans, 3,3′-dichlorospirodinaphthopyrans, 3-benzylspirodinaphthopyrans, 3-methylnaphthylpyrans (3-methoxy) Benzo) spirodinaphthopyran, 3-propylspirobenzopyran and the like.

  These can be used alone or in admixture of two or more.

  The electron-accepting developer contains at least one zinc complex or oxozirconium complex of the carboxylic acid represented by the general formula [I] or [II]. Other electron-accepting color developers can be used in combination as long as the desired effects are not impaired. The electron-accepting developer that can be used in combination is not particularly limited as long as it is an acidic substance that is generally used for heat-sensitive recording materials. For example, a phenol derivative, an aromatic carboxylic acid derivative N, N′-diarylthiourea derivative, a zinc salt of a salicylic acid derivative, or the like can be used.

  Specific examples of the binder used in the heat-sensitive recording material include the following. Starch, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, poval, modified poval, sodium polyacrylate, acrylate / acrylate copolymer, acrylate / acrylate / methacrylic acid terpolymer Polymers, water-soluble polymers such as alkali metal salts of styrene / maleic anhydride copolymers, alkali metal salts of ethylene / maleic anhydride copolymers, polyvinyl acetate, polyurethane, polyacrylates, styrene / butadiene Copolymer, Acrylonitrile / butadiene copolymer, Acrylate ester / Butadiene copolymer, Ethylene / vinyl acetate copolymer, Ethylene / vinyl chloride copolymer, Polyvinyl chloride, Ethylene / vinylidene chloride copolymer, Poly salt Vinylidene, polycarbonate, latex such as polyvinyl butyral, and the like, but not limited thereto.

  In order to enhance the strength of the recording layer, a crosslinking agent may be used in combination. Specific examples include isocyanates, amines, phenols, epoxies, boric acid derivatives and the like.

  As the support used in the thermal recording material of the present invention, paper, various nonwoven fabrics, woven fabric, synthetic resin film, synthetic resin laminated paper, synthetic paper, metal foil, glass, etc., or a composite sheet combining these, It can be arbitrarily used depending on the case, and may be transparent, translucent or opaque. Moreover, it is not limited to these.

  The layer structure of the heat-sensitive recording material of the present invention may be only the heat-sensitive recording layer. If necessary, a protective layer can be provided on the heat-sensitive recording layer. An intermediate layer can also be provided between the thermosensitive recording layer and the support. In this case, the protective layer and / or the intermediate layer may be composed of a plurality of layers of two layers or three or more layers. Further, a material in which information can be recorded electrically, magnetically, or optically may be included in the heat-sensitive recording layer and / or the surface on which the other layer and / or the heat-sensitive recording layer is provided and / or the opposite surface. good. In addition, a back coat layer can be provided on the surface opposite to the surface on which the heat-sensitive recording layer is provided for the purpose of preventing curling and antistatic.

  The heat-sensitive recording layer can be obtained by a method in which a dispersion obtained by finely pulverizing the metal complex of the present invention, an electron-donating dye precursor, and a binder component in water is coated on a support or printed and dried. it can. In this case, each component may be included in a single layer to form a multilayer structure.

The coating amount of the heat-sensitive recording layer is determined by the amount of the dye precursor that is the color forming component and the amount of the electron accepting developer. Usually, the coating amount of the dye precursor is 0.1 to 1.0 g / m ^2. . The amount of the electron-accepting developer is added in an amount of 5 to 400% by weight with respect to the dye precursor, with 20 to 300% by weight being particularly preferable.

  The heat-sensitive recording layer and / or the protective layer and / or the intermediate layer includes diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin. In addition to pigments such as resins, higher fatty acid metal salts such as zinc stearate and calcium stearate, waxes such as paraffin, polyethylene, stearamide, and castor wax, dispersants such as sodium dioctyl sulfosuccinate, and interfaces An activator, a fluorescent dye, and the like can also be included.

  When an image is formed using laser light, a photothermal conversion material may be contained in the recording layer. Further, a layer containing a photothermal conversion material may be provided adjacent to the heat-sensitive recording layer. Examples of the photothermal conversion material include cyanine dyes, phthalocyanine compounds, and metal dithiolate compounds.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples. In addition, the number of parts and percentage in an Example are based on a weight.

(Synthesis of Exemplified Compound A-3)
67 g of 4-hydroxybenzaldehyde and 56 g of γ-aminobutyric acid are dissolved in 200 ml of acetic acid and heated and stirred at 100 ° C. 92 g of methyl propiolate was dissolved in 50 ml of acetic acid and added dropwise to the reaction solution heated to 100 ° C. After completion of the dropwise addition, the mixture was further heated at 100 ° C. for 6 hours, and then cooled to room temperature to precipitate crystals. The crystals were collected by suction filtration, washed with 300 ml of diethyl ether and air-dried to obtain a crude product. This was recrystallized from 1500 ml of methanol to obtain 54 g of Compound A-3. Melting point: 208-215 ° C.

(Synthesis of Zinc / Metal Complex of Exemplified Compound A-3)
25 g of Exemplified Compound A-3 was placed in 600 ml of water and stirred. 70 ml of 1N sodium hydroxide aqueous solution was added to completely dissolve Exemplified Compound A-3, and then 4.5 g of zinc (II) chloride was dissolved in 300 ml of water and added dropwise. Precipitated yellowish crystals were collected by filtration, washed with 200 ml of water, and then dried in a vacuum dryer at 35 ° C. for 5 hours to obtain 24 g of zinc / exemplary compound A-3 metal complex. Melting point; gradually decomposes at 130-150 ° C.

(Synthesis of Exemplary Compound B-1)
66 g of terephthalaldehyde acid and 60 g of tyramine are dissolved in 200 ml of acetic acid and heated and stirred at 100 ° C. 74 g of methyl propiolate was dissolved in 50 ml of acetic acid and added dropwise to the reaction solution heated to 100 ° C. After completion of the dropwise addition, the mixture was further heated at 100 ° C. for 24 hours, and then acetic acid was distilled off from the reaction solution under reduced pressure. The residue was purified by silica gel column chromatography using a mixed solvent of chloroform / methanol = 30/1 as a developing solvent. The developing solvent was distilled off under reduced pressure, and 1000 ml of diethyl ether was added to the remaining oily substance, followed by stirring to precipitate crystals. The precipitated crystals were collected by filtration, washed with 500 ml of diethyl ether, and air-dried to obtain 80 g of Exemplified Compound B-1. Melting point: 208-209 ° C. (decomposition).

(Synthesis of Zinc / Exemplary Compound B-1 Metal Complex)
30 g of Exemplified Compound B-1 was placed in 1200 ml of water and stirred. 70 ml of 1N aqueous sodium hydroxide solution was added to completely dissolve the exemplified compound B-1, and 4.7 g of zinc (II) chloride was dissolved in 300 ml of water and added dropwise. Precipitated yellowish crystals were collected by filtration, washed with 600 ml of water, and then dried in a vacuum dryer at 35 ° C. for 5 hours to obtain 32 g of zinc / exemplary compound B-1 metal complex. Melting point: Crystalline type change around 140 ° C. Disassembly point is unclear.

(Synthesis of Exemplary Compound A-6)
67 g of 3-hydroxybenzaldehyde and 56 g of γ-aminobutyric acid are dissolved in 200 ml of acetic acid, and heated and stirred at 100 ° C. 92 g of methyl propiolate was dissolved in 50 ml of acetic acid and added dropwise to the reaction solution heated to 100 ° C. After completion of the dropwise addition, the mixture was further heated at 100 ° C. for 22 hours, and then cooled to room temperature to precipitate crystals. The crystals were collected by suction filtration, washed with 1000 ml of diethyl ether and air-dried to obtain a crude product. This was recrystallized from 7000 ml of 2-propanol to obtain 88 g of Exemplified Compound A-6. Melting point: 235-238 ° C. (decomposition).

(Synthesis of Metal Complex of Oxyzirconium / Exemplary Compound A-6)
30 g of Exemplified Compound A-6 was placed in 1900 ml of water and stirred. 80 ml of 1N aqueous sodium hydroxide solution was added to completely dissolve the exemplified compound A-6, and then 12.9 g of zirconium chloride (IV) octahydrate was dissolved in 200 ml of water and added dropwise. The precipitated yellowish crystals were collected by filtration, washed with 200 ml of water, and then dried in a vacuum dryer at 35 ° C. for 5 hours to obtain 33 g of a metal complex of oxyzirconium / Exemplary Compound A-6. Melting point: 220-227 ° C. (decomposition)

(A) Preparation of heat-sensitive coating liquid 35 parts of 3-dibutylamino-6-methyl-7-anilinofluorane, which is a dye precursor, is pulverized in a pole mill for 24 hours together with 80 parts of a 2.5% aqueous polyvinyl alcohol solution, and the dye is dispersed. A liquid was obtained. Next, 100 parts of the metal complex of zinc / exemplary compound A-3 was pulverized together with 300 parts of a 2.5% aqueous polyvinyl alcohol solution with Dynomill (a sand mill manufactured by WEB) to obtain an electron-accepting developer dispersion. A heat-sensitive coating solution was prepared according to the formulation in Table 1 using the two types of dispersions.

(B) Preparation of heat-sensitive coated paper A coating liquid having the following composition was applied to a base paper having a basis weight of 40 g / m ^{2 so} that the solid smear amount was 9 g / m ² and dried to obtain a heat-sensitive coated paper. Produced.

(C) Preparation of heat-sensitive recording material The heat-sensitive coating liquid prepared in (A) was applied onto the heat-sensitive coated paper prepared in (B) so as to have a solid smear of 4 g / m ² and dried. A heat-sensitive recording material was prepared.

  A thermosensitive recording material was produced in the same manner as in Example 4 except that instead of the metal complex of zinc / exemplary compound A-3 in Example 4, a metal complex of zinc / exemplary compound B-1 was used.

  A thermosensitive recording material was prepared in the same manner as in Example 4 except that the metal complex of oxyzirconium / Exemplary Compound A-6 was used instead of the metal complex of Zinc / Exemplary Compound A-3 in Example 4.

(Comparative Example 1)
A thermosensitive recording material was prepared in the same manner as in Example 4 except that zinc salt of 3,5-di (α-methylbenzyl) salicylic acid was used in place of the metal complex of zinc / Exemplary Compound A-3 in Example 4. did.

  A color development test was performed on the heat-sensitive recording materials prepared in Examples 4 to 6 and Comparative Example 1. A heat-resistant PET film having a thickness of 5 μm was stacked on the heat-sensitive layer, and then heated using a heat stamp evaluation apparatus (Toyo Seiki; HG-100) at 150 ° C. for 1 second and 180 ° C. for 3 seconds. After removing the heat-resistant PET film, visual evaluation was performed. The results are shown in Table 3. As is apparent from Table 3, the heat-sensitive recording material prepared using the metal complex of the present invention showed sufficient color developability even when heated at 150 ° C. for 1 second.

  For the sample that was heated and colored in Example 7, the storage characteristics of the image area and the storage characteristics of the non-image area were evaluated. Evaluation of the storage characteristics of the image portion was performed by a lap resistance test. The storage characteristics of the non-image area were evaluated by a heat resistance test.

[Image wrap resistance test]
A commercially available wrap was placed on the image portion of each color sample, and the state of decoloration of the image portion after being stored for 24 hours in an environment of 40 ° C. under a load of ² g / cm ² was visually determined. ○ indicates that the image portion remains almost unerased, and × indicates that the image density is considerably lowered.

[Heat resistance test]
In the heat resistance test, the whiteness of the non-image area after each sample was stored at 60 ° C. for 24 hours was visually determined. ○ indicates that whiteness equivalent to that before heat storage is maintained, and × indicates that color development is considerably caused by heat storage.

  Table 4 shows the results of the lap resistance test for the image area and the heat resistance test for the non-image area.

  As is apparent from the results in Table 4, it can be seen that the heat-sensitive recording material of the present invention is excellent in storage characteristics.

  As an application example of the present invention, a heat-sensitive recording material excellent in both storage characteristics of a color image portion and storage characteristics of a non-image portion can be mentioned.

Claims (2)

A metal complex synthesized from a carboxylic acid represented by the following general formula [I] or the following general formula [II] and a divalent zinc salt or a tetravalent oxozirconium halide.

(In the general formula [I], R ₁ and R ₂ represent a hydrogen atom or an alkyl group, R ₃ and R ₄ represent an alkyl group, and Ar ₁ represents an aryl group having a phenolic hydroxyl group as a substituent. L represents carbon. Represents an alkylene group having a number of 1 or more and 12 or less.)

(In the general formula [II], Ar ₂ represents an aryl group or aralkyl group having a phenolic hydroxyl group as a substituent, R ₅ and R ₆ represent a hydrogen atom or an alkyl group, and R ₇ and R ₈ represent an alkyl group. Q represents a divalent aromatic hydrocarbon residue.)   A thermosensitive recording material comprising a carboxylic acid represented by general formula [I] or general formula [II] and a metal complex synthesized from a divalent zinc salt or a tetravalent oxozirconium halide.