JP2531960B2 - Colorable phthalide compound and thermosensitive recording material using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel color-forming phthalide compound, and more specifically, to a novel color-forming phthalide compound having absorption in the near infrared region and the compound as a color-forming component. The present invention relates to a near infrared absorption heat-sensitive recording material.

[Prior art]

BACKGROUND OF THE INVENTION Thermosensitive recording materials that utilize the coloring reaction between a leuco dye and a color developer are currently widely used in facsimiles, printers, bar code labels, ticket papers and the like. Typical leuco dyes used in heat-sensitive recording materials are:
Examples include blue-coloring dyes of crystal violet lactone and black-coloring dyes of 3-amino-6-methyl-7-anilinofluorane derivatives. These dyes have high density and high contrast, and also as a thermosensitive recording material. Performance, that is, image stability and storage stability are also generally good. In recent years, optical character readers and label bar code readers have been developed and their usage rate is increasing. In these devices, the light wavelength using a light emitting diode or semiconductor radar is 700 nm or more as the light source. These light sources are also commonly used. However, the above-mentioned blue-coloring dye and black-coloring dye have almost no light absorption in the near infrared region of 700 nm or more, and therefore the above-mentioned reading device cannot read the color. Therefore, there has been a strong demand for new development of a leuco dye having a light-absorbing wavelength of 700 nm or more in a color former.

As a leuco dye having absorption in the near-infrared region, for example, there is a proposal in Japanese Patent Publication No. 58-27825, but the compounds disclosed therein are suitable for use in pressure-sensitive recording materials. It is a chromatic compound, and there are many problems when this compound is used as a heat-sensitive recording material, and it is very difficult to apply it in practice. For example, 3- (4-dimethylaminophenyl) -3- [bis-1,1- (p-dimethylaminophenyl) -ethyleno-2] -6-dimethylaminophthalide disclosed in this publication is near infrared. Absorption characteristics are relatively excellent, but when used as a thermal recording material,
The background fogging is remarkably large and the storage stability such as heat resistance and moisture resistance is remarkably inferior. In addition, 3 disclosed in the publication
-(4-Diethylaminophenyl-1-yl) -3-
[Bis-1,1- (p-diethylaminophenyl) -ethyleno-2] phthalide and 3- (4-diethylamino-2)
-Methoxy-1-yl) -3-([bis-1,1- (p-
Compounds such as diethylaminophenyl) -ethyleno-2] phthalide have a relatively small background fog, but have a drawback that they have a low melting point, are poor in heat-resistant storage stability, have poor light resistance, and have a marked yellowing of the background. -(N, 4'-Dimethyl-2-methoxydiphenylamine-1-yl) -3-
[2-Carboethoxy-bis-1,1- (p-dimethylaminophenyl) -ethyleno-2] phthalide has a problem in that it is inferior in practical use due to its poor absorption property of near infrared light.

The main physical properties required for a leuco dye as a heat-sensitive recording material are (i) the leuco body is colorless or light-colored, (ii) the melting point is not too low, that is, 100 to 250 ° C, preferably 140 to 200 ℃ and (iii) moderate speed of color development during heating (dye that develops easily gives a strong image, but has the drawback of easily causing background fog or background fog during high temperature storage, Conversely, dyes with slow color development have the drawback of low density). On the other hand, it is preferable that the leuco dye as a pressure-sensitive recording material is a leuco body which is colorless or light-colored, but the melting point is not a particularly required physical property, and rather it is most important that it has a high solubility in oil. It is preferable that the color development speed is as fast as possible.

That is, the physical properties required for a leuco dye for a heat-sensitive recording material and the physical properties required for a leuco dye for a pressure-sensitive recording material are significantly different. Therefore, a new leuco dye having material properties required for a heat-sensitive recording material is desired. Has been done.

〔Purpose〕

An object of the present invention is to provide a novel leuco dye having near-infrared light absorbing physical properties suitable for a heat-sensitive recording material,
Specifically, it has a melting point necessary for a leuco dye for a heat-sensitive recording material, is excellent in background whiteness, heat resistance and moisture-resistant storage property, and is also excellent in absorption characteristics of near infrared light. The purpose is to provide a recording material.

[Structure] According to the present invention, as a first invention, a color-producing phthalide compound represented by the following general formula (I) is provided, (In the formula, R ₁ represents a methyl group, an ethyl group or a methoxy group,
R ₂ is a methyl group or an ethyl group, R ₃ is a hydrogen atom, a methyl group or a methoxyl group, and R ₄ , R ₅ , R ₆ , R ₇ , R ₈ and R ₉
Each independently represent a methyl group or an ethyl group. Further, as a second invention, there is provided a heat-sensitive recording material characterized by using the color-producing phthalide compound represented by the general formula (I) as a color-forming component.

The color-forming phthalide compound represented by the general formula (I) in the present invention is usually a white or slightly yellow powder,
It shows strong absorption in the near-infrared region of 750 nm and above, and exhibits a deep blue color when it comes in contact with a color developer.

Typical examples of the compound represented by the general formula (I) include (1) 3- (N, 4′-dimethyldiphenylamine-4-
Yl) -3- {bis-1,1- (p-dimethylaminophenyl) -ethyleno-2} -6-dimethylaminophthalide (2) 3- (N-methyl-4′-methoxydiphenylamine-4-yl) ) -3- {bis-1,1- (p-dimethylaminophenyl) -ethyleno-2} -6-dimethylaminophthalide, but other specific examples include those shown in Table 1. To be

The compound represented by the general formula (I) of the present invention is, for example, dehydration condensation of a keto acid compound represented by the following general formula (II) and an ethylene compound represented by the following general formula (III) using various condensing agents. It can be produced by reacting.

(In the formula, R _{1 to} R ₉ are as described above) In this case, a Friedel-Crafts type catalyst can be generally used as the condensing agent, and typical examples thereof include acetic anhydride, propionic anhydride, phosphorus oxychloride, and trisulfate. Phosphorus chloride,
Examples thereof include various complexes of sulfuric acid, polyphosphoric acid and boron trifluoride. Further, if necessary, a solvent can be appropriately selected and used in this reaction. Typical examples thereof include benzene, toluene, xylene, chlorobenzene, 0-dichlorobenzene, nitrobenzene, ethyl ether, petroleum ether, tetrahydrofuran, tetrahydrofurfuryl alcohol and the like.

The color-developing phthalide compound represented by the general formula (I) of the present invention is very useful as a color-developing agent in a heat-sensitive recording material. That is, the heat-sensitive recording material using the color-developing phthalide compound of the present invention as a color-developing agent has high background whiteness and image density, is excellent in absorption in the near-infrared region, and is also excellent in heat resistance and moisture resistance storage stability. .

The color-forming phthalide compound of the present invention can be used alone or in combination of two or more kinds. Although the color tone of the compound of the present invention is dark blue, a general-purpose leuco dye other than the general formula (I) may be used in combination for the purpose of adjusting the color tone. Specific examples in this case include the following.

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-diethylaminophenyl) -6-diethylaminophthalide, 3,3-bis ( p-diethylaminophenyl) phthalide, 3,3-bis (p-dimethylaminophenyl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-diethylaminophthalide, 3-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3- (N-isobutyl-N-ethylamino) -6-methyl-7-chlorofluorane, 3- (N-cyclohexyl-N-methylamino)- 6
-Methyl-7-chlorofluorane, 3- (Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl-7-anilinofluorane, 3- (N-isoamyl-N-ethylamino) -6-methyl-7-anilinofluorane, 3- (N-furfuryl-N-amino) ) -6-Methyl-
7-anilinofluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-dibutylamino-7- (o-chloroanilino) fluorane, 3-diethylamino-6-methyl-7-dibenzylaminofluorane, 3- (N-methyl-N-isopropylamino) -6-
Methyl-7-anilinofluorane, 1,5-bis (p-dimethylaminophenyl) -3-
(P-Methylphenylsulfonyl) pentadiene (1,
4), 1,5-bis (p-dimethylaminophenyl) -3-phenylsulfinyloxypentadiene (1,4), 3,6-bis (dimethylamino) fluorene spiro (9,
3 ')-6'-Dimethylaminophthalide.

Further, in the present invention, the developer that develops the color-forming phthalide compound includes an inorganic or organic acidic substance. Examples of the inorganic acidic substance include clay, activated clay, activated silica, zinc chloride, aluminum chloride, zinc thiocyanate, acid-treated silica, zinc oxide and the like. Examples of the organic acidic substance include compounds having a carboxyl group, a phenol group, a sulfonic acid group, a urea group, a thiourea group or a phosphoric acid group, as well as polyvalent metal salts of carboxylic acids, organic metal compounds, and complex compounds of inorganic acids. Etc.,
Specific examples thereof include the following.

4,4'-isopropylidene bisphenol 4,4'-cyclohexylidene bisphenol, 4,4'-isopropylidene bis (2-chlorophenol), 4,4'-isopropylidene bis (2-tert-butylphenol), 4 4,4'-thiobis (2-tert-butyl-5-methylphenol), 4,4'-thiobis (2-methylphenol), 4,4'-thiobis (2-isopropyl-5-methylphenol), 4, 4'-diphenol sulfone, 4,2'-diphenol sulfone, 4-hydroxy-4'-isopropyldiphenyl sulfone, 4-hydroxydiphenyl sulfone, 4-hydroxy-4'-chlorodiphenyl sulfone, 4-hydroxy-4 ' -Isopropoxydiphenyl sulfone, 4-hydroxy-4'-benzyloxydiphenyl sulfone, 4-hydroxy-4'-tert-butyloxydiphenyl sulfone, 4-hydroxy-4'-allyloxydiphenyl sulfone, 2,2'-diallyl-4,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-secondary Butyloxydiphenyl sulfone, 4-hydroxy-4'-isobutyloxydiphenyl sulfone, benzyl-p-hydroxybenzoate, isopropyl-p-hydroxybenzoate, benzyl- (4-hydroxy-3-chlorobenzoate), isobutyl-p-hydroxybenzoate , Secondary butyl-p-hydroxybenzoate, 5-hydroxydimethyl phthalate, benzyl-2-hydroxy-6-naphthoate, isopropyl-2-hydroxynaphthoate, salicyl salicylate , Salicylanilide, 5-chlorosalicylanilide, salicyl- (m-chloroanilide), salicyl- (m-trifluoromethylanilide), diphenylthiourea, bis (m-chlorophenyl) thiourea, bis (m-methylphenyl) thiourea , 1,5-bis (p-hydroxyphenylthio) pentane, bis (p-hydroxyphenylthioethyl) ether, methylenebis (oxyethylenethio) phenol, zinc salicylate, zink-3,5-ditertiary butyl salicyt Tinc, Tinc-3-benzyl salicylate, Tinc-3,5-dibenzyl salicylate, Tinc-2-oxy-3-naphthoate, Tinc-1-oxy-2-naphthoate, Tinc chloride antipyrine complex, Tinc thiocyanate Anate antipyrine complex, twink m-nitrobenzoate, 4-hydroxybenzophenone and the like.

In the present invention, various conventional binders can be appropriately used for binding and supporting the leuco dye and the developer on a support. Specific examples of such a binder include the following.

Polyvinyl alcohol, starch and its derivatives, hydroxymethyl cellulose, hydroxyethyl cellulose,
Cellulose derivatives such as carboxymethyl cellulose, methyl cellulose, ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide / acrylic acid ester copolymer, acrylamide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer In addition to water-soluble polymers such as alkali salts, isobutylene / maleic anhydride copolymer alkali salts, polyacrylamide, sodium alginate, gelatin, casein, polyvinyl acetate, polyurethane, polyacrylic acid,
Emulsion of polyacrylic acid ester, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene / vinyl acetate copolymer, etc., latex of styrene / butadiene copolymer, styrene / butadiene / acrylic copolymer, etc.

Further, in the present invention, if necessary, an auxiliary additive component commonly used in this kind of heat-sensitive and pressure-sensitive recording materials, for example,
Fillers, surfactants, heat-fusible substances (or lubricants) and the like can be used in combination. In this case, as the filler, for example,
Calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay,
Inorganic fine powders such as talc and surface-treated calcium and silica, as well as organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be mentioned. Examples of the functional substance include stearic acid amide, behenic acid amide, ethylenebisstearylamide, methylenebisstearylamide, p-benzyl-biphenyl, m-terphenyl, p-methoxycarbonyloctadecylcarbamoylbenzene, 1-hydroxy-2-. Phenyl naphthoate,
Examples thereof include ethylene bis (m-methylphenyl) ether and β-naphthylbenzyl ether, which generally have a melting point of 50 to 50.
A white substance with a low water solubility of about 150 ° C is used.

In order to prepare the heat-sensitive recording material of the present invention, fine paper, thin paper, coated paper, art paper, paper such as mirror-coated paper, synthetic paper, polyester film, cellulose triacetate film, etc. Apply a thin coating of a liquid in which a color developer, binder, etc. is dispersed or dissolved with a wire bar, etc., dry at a temperature of from room temperature to about 80 ° C for several minutes to several hours, and calender the resulting coated paper. Can be created by. A protective layer such as a resin may be further provided on the heat sensitive layer, or an intermediate layer may be provided between the heat sensitive layers of the support. The amount of dye attached to the support is usually 0.1 to 1.0 g /
About m ² is preferable, and the dry adhesion amount of the color developer is preferably 0.5 to 10 times the dye weight.

〔effect〕

The color-forming phthalide compound represented by the above general formula (I) of the present invention has a strong absorption ability in the near infrared region and, moreover, has a melting point required as a leuco dye for a heat-sensitive recording material. Further, the heat-sensitive recording material using the phthalide compound of the present invention as a color former is not only excellent in near-infrared light absorption characteristics, but also has high background whiteness and image density, and furthermore, heat resistance and moisture resistance storage stability of dye images. Is excellent.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 3- (N, 4'-Dimethylphenylamine-4-yl)-
3- {bis-1,1- (p-dimethylaminophenyl)-
Synthesis of ethyleno-2} -6-dimethylaminophthalide [compound specific example (1)] 4- (4-dimethylamino-2-carboxybenzoyl) -4 ', N-dimethyldiphenylamine 2.10 g and 1,1-
Bis- (p-dimethylaminophenyl) ethylene 1.35g
And 10 ml of acetic anhydride are mixed, heated and stirred at 60 ° C. for 1 hour, and then poured into diluted ammonia water to adjust the pH to 8. The formed precipitate was collected by filtration, stirred with toluene-caustic soda water for 1 hour at 70 ° C., and the solid obtained by evaporating toluene was recrystallized from methanol to obtain 3.05 g of amorphous yellow powder. It was The obtained powder does not have a melting peak with a differential calorimeter, but the melting point is 132 to 141 ° C. visually on a hot plate,
The powder also showed a deep blue color on silica gel.

Example 2 3- (N-methyl-4′-methoxydiphenylamine-
Synthesis of 4-yl) -3- {bis-1,1- (p-dimethylaminophenyl) -ethyleno-2} -6-dimethylaminophthalide [Compound Specific Example (2)] 4- (4-dimethylamino) -2-carboxybenzoyl) -4'-methoxy-N-methyldiphenylamine 2.
By performing the same treatment as in Example 1 except that 15 g was used in place of 2,10 g of 4- (4-dimethylamino-2-carboxybenzoyl) -4 ', N-dimethyldiphenylamine, an amorphous fine powder was obtained. 3.10 g of a yellow powder was obtained. The powder had no absorption peak with a differential thermometer, but the melting point visually observed on a hot plate was 110 to 115 ° C., and the powder showed a deep blue color on silica gel.

Examples 3 to 8 and Comparative Examples 1 to 4 A mixture having the following composition was used, and the average particle size (measured by Coulter Electronics Model TA-II manufactured by Coulter Electronics Co., Ltd.) was 1 μm or less and 5 μm using a disperser.
[Dispersion A] was prepared by pulverizing and dispersing until the following content was 95% or more. In addition, all the parts and% shown below are based on weight.

[Dispersion A]

Compound [A] in Table-2 20 parts Polyvinyl alcohol 10% aqueous solution 20 parts Dispersion aid 1 part Water 60 parts Also, using a disperser, until the average particle diameter becomes 2 μm or less. [Dispersion liquid B] was prepared by pulverizing and dispersing.

[Dispersion B]

[Group B] compound in Table-2 10 parts p-Methoxycarbonyloctadecylcarbamoylbenzene 5 parts Polyvinyl alcohol 10% aqueous solution 20 parts Calcium carbonate fine particles 10 parts Zinc stearate 40% dispersion 5 parts Water 130 parts To 10 parts of the resulting [dispersion A] and 60 parts of [dispersion B], 10 parts of water and 5 parts of a 40% dispersion of styrene / butadiene / acrylic copolymer were mixed and stirred to obtain a heat-sensitive coating solution. .

This is applied to a commercially available high-quality paper having a basis weight of about 50 g / m ² using a lab coating rod so that the dry solid content of the dye is 0.5 g / m ² and dried to provide a heat-sensitive layer, and then the surface thereof. A thermal recording material was prepared by calendering the layer surface so that the smoothness was about 300 seconds.

The resulting heat-sensitive recording material was subjected to solid black printing with a thermal printing simulator [Matsushita Electronics Co., Ltd.], and the density was measured with a Macbeth densitometer RD-914. Table 2 shows the measurement results.

The PCS value was calculated by measuring the reflection absorption spectrum with a reflection spectrophotometer (Hitachi 330) and using the following conversion formula.

However, A ₀ in the above formula is the absorbance at 780 nm of the bare skin,
A ₁ is the absorbance at 780 nm in the image area.

Further, the above samples were tested for heat resistance and humidity resistance. The results are also shown in Table-2. The test was conducted as follows.

(1) Heat resistance: The density of the background part was measured after storing for 24 hours under a dry condition of 60 ° C.

(2) Moisture resistance: The density of the background part was measured after storage for 24 hours at 40 ° C and 90% humidity.

As is clear from Table-2, the heat-sensitive recording material using the phthalide compound of the present invention has not only a white background and a high image density as compared with Comparative Examples, but also excellent absorption in the near infrared region, High PCS value. Further, since it is excellent in heat-resistant storage property and moisture-resistant storage property, it can be seen that it is remarkably excellent as a dye for a heat-sensitive recording material which requires various functional physical properties. In particular, it is understood that the whitenesses of the background portion at the initial stage and after storage are superior to those of Comparative Examples 1 and 2, and the image density and PCS value are significantly superior to those of Comparative Examples 3 and 4.

Claims (2)

(57) [Claims] 1. A color-forming phthalide compound represented by the following general formula. (In the formula, R ₁ represents a methyl group, an ethyl group or a methoxy group,
R ₂ is a methyl group or an ethyl group, R ₃ is a hydrogen atom, a methyl group or a methoxyl group, and R ₄ , R ₅ , R ₆ , R ₇ , R ₈ and R ₉
Each independently represent a methyl group or an ethyl group. ) 2. A heat-sensitive recording material comprising a color-forming phthalide compound represented by the following general formula as a color-forming component. (In the formula, R ₁ represents a methyl group, an ethyl group or a methoxy group,
R ₂ is a methyl group or an ethyl group, R ₃ is a hydrogen atom, a methyl group or a methoxyl group, and R ₄ , R ₅ , R ₆ , R ₇ , R ₈ and R ₉
Each independently represent a methyl group or an ethyl group. )