JPH08276654A - Indolylazaphthalide compound and recording material employing it - Google Patents

Abstract

PURPOSE: To provide cyan color images from blue with good density, and reduce optical stains in non-image forming parts by using a specific indolylazaphthalide compound as electron donating colorless dyes for a recording material. CONSTITUTION: The formula represents a 3-(4-di-n-propylamino-2- methylephenyl)-3-(1-alkyl-2-methylidol-3-yl)-4-azaphthalide compound. Also, the recording material includes a compound in the formula in the recording material employing electron donating colorless dyes and an electron accepting compound. Besides, R represents an alkyl group having a carbon number of 1-10. The alkyl group is preferably a 1-8C R. In addition, these are optionally replaced by a methoxy group, an ethoxy group, a phenoxy group, a phenyl group, a 2-methoxyethoxy group, a chlorine atom, and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an indolyl azaphthalide compound and a recording material using the indolyl azaphthalide compound. The indolyl azaphthalide compound of the present invention is useful as a recording material using an electron-donating colorless dye and an electron-accepting compound, particularly as an electron-donating colorless dye for recording materials such as pressure-sensitive recording materials and heat-sensitive recording materials. . The present invention also relates to a recording material which gives a blue to cyan image of good density and which has less light stain in the non-image areas.

[0002]

2. Description of the Related Art Recording materials using an electron-donating colorless dye and an electron-accepting compound are pressure-sensitive paper, thermal paper, photosensitive pressure-sensitive paper,
It is already well known as an electrically conductive recording paper and a thermal transfer paper. For example, British Patent 2140449 and US Patent 44
80052, 4436920, Japanese Patent Publication No. 60-2399.
2, JP-A-57-179836 and 60-12355.
6 and 60-123557. As a recording material, in recent years, researches have been earnestly conducted to improve characteristics such as image density, fastness of an image portion and fastness of a white background portion.
Various types of electron-donating colorless dyes that give blue to cyan images, such as triphenylmethanephthalide compounds, phenothiazine compounds, and indolylphthalide compounds, are known. Among the indolyl phthalide compounds, some examples of so-called indolyl azaphthalide compounds in which the carbon atom of the benzene ring of the phthalide part is substituted with a nitrogen atom are known. Specifically, Japanese Patent Publication No. 61-4856,
JP 61-168664, JP 61-29165
4, JP-A-62-270662 and the like. Although these give a blue to cyan image of good density, they have the problem that light stains in white areas are easily generated.

The inventors of the present invention have made extensive studies as to a compound satisfying the above-mentioned properties with an electron-donating colorless dye that gives a blue to cyan image, and as a result, have shown that the novel indolyl azaphthalide compound has the desired performance. I found something to meet.

[0004]

SUMMARY OF THE INVENTION The present invention provides an electron-donating colorless dye which gives a blue to cyan image of good density and has less light stain in the non-image area, and a recording material using the same. is there.

[0005]

Means for Solving the Problems The above-mentioned problems can be solved in a recording material using an indolyl azaphthalide compound represented by the following general formula (I) and an electron-donating colorless dye and an electron-accepting compound. It is achieved by a recording material containing at least one indolyl azaphthalide compound represented by (I). General formula (I)

[0006]

Embedded image

In the above formula, R represents an alkyl group having 1 to 10 carbon atoms.

In the above general formula (I), R is preferably an alkyl group having 1 to 8 carbon atoms. These are further methoxy group, ethoxy group, phenoxy group, phenyl group, 2-
It may be substituted with a methoxyethoxy group or a chlorine atom. Specific examples of R include methyl group, ethyl group, n-propyl group, n-butyl group, i-butyl group, n-pentyl group, i-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group. Group, benzyl group, 2-methoxyethyl group, 2- (2-methoxyethoxy) ethyl group, 2
-Phenoxyethyl group, 2-phenoxypropyl group, 3
-Phenoxypropyl group, 2-chloroethyl group and the like are preferable.

Specific examples of the indolyl azaphthalide compound according to the present invention are shown below, but the present invention is not limited thereto. (1) 3- (4-di-n-propylamino-2-methylphenyl) -3- (1-methyl-2-methylindol-3-yl) -4-azaphthalide (2) 3- (4-di -N-Propylamino-2-methylphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide (3) 3- (4-di-n-propylamino-2-methyl Phenyl) -3- (1-n-butyl-2-methylindol-3-yl) -4-azaphthalide (4) 3- (4-di-n-propylamino-2-methylphenyl) -3- (1 -N-pentyl-2-methylindol-3-yl) -4-azaphthalide (5) 3- (4-di-n-propylamino-2-methylphenyl) -3- (1-n-octyl-2- Methylindol-3-yl) -4-azaphthali De (6) 3- (4-di-n-propylamino-2-methylphenyl) -3- (1-β-methoxyethyl-2-methylindol-3-yl) -4-azaphthalide (7) 3- (4-Di-n-propylamino-2-methylphenyl) -3- [1- (2-methoxyethyl) -2-
Methylindol-3-yl] -4-azaphthalide

The indolyl azaphthalide compound according to the present invention may be used alone or in combination of two or more kinds. Further, it may be a mixture containing a 7-azaphthalide derivative produced as a by-product during production. When the 7-azaphthalide compound is contained, the 7-azaphthalide compound is preferably 10 mol% or less, more preferably 5 mol% or less of the 4-azaphthalide compound.

The indolyl azaphthalide compound according to the present invention is disclosed in JP-A-62-270662 and JP-B-3-16954.
It can be produced by a known method described in the above.

The indolyl azaphthalide compound according to the present invention is a conventionally known triphenylmethane phthalide compound, fluorane compound, phenothiazine compound, indolyl phthalide compound, leuco auramine compound, rhodamine lactam compound. It can be used in combination with various compounds such as compounds, triphenylmethane compounds, triazene compounds, spiropyran compounds and fluorene compounds. Specific examples of the phthalides include US Reissue Patent Specification No. 23,024 and US Patent Specification No. 3,491,1.
No. 11, No. 3,491, 112, No. 3,491,
116 and 3,509,174, specific examples of fluoranes are US Pat. No. 3,624,107,
No. 3,627,787, No. 3,641,011
No. 3,462,828, No. 3,681,39
No. 0, No. 3,920,510, No. 3,959,5
71, specific examples of spiro dipyrans are US Pat. No. 3,971,808, and pyridine compounds and pyrazine compounds are US Pat. Nos. 3,775,424 and 3,853,869; No. 4,246,318 and specific examples of fluorene compounds are described in JP-A-63-94878.

The coating amount of the electron-donating colorless dye according to the present invention is not particularly limited, but is preferably 0.1 to 2.0 g / m ² , particularly 0.2 to 1.5 g / m ² .

Examples of the electron-accepting compound used in the recording material of the present invention include phenol derivatives, salicylic acid derivatives, metal salts of aromatic carboxylic acids, acid clay, bentonite, novolac resins, metal-treated novolac resins, metal complexes and the like. To be Examples of these are Japanese Patent Publication No. 40-930.
9, JP-B-45-14039, JP-A-52-140.
483, JP-A-48-51510, JP-A-57-2.
10886, JP-A-58-87089, JP-A-59
-11286, JP-A-60-176795, JP-A-61-95988 and the like.

The weight ratio of the electron-donating colorless dye and the electron-accepting compound used is preferably 1:10 to 1: 1 and more preferably 1: 5 to 2: 3.

The indolyl azaphthalide compound according to the present invention may be used in combination with conventionally known ultraviolet absorbers, optical brighteners and antioxidants.

Preferred UV absorbers that can be used in combination are benzophenone UV absorbers, benzotriazole UV absorbers, salicylic acid UV absorbers, cyanoacrylate UV absorbers, oxalic acid anilide UV absorbers, and the like. Can be mentioned. Examples of these are JP-A-47-10537 and JP-A-58-111942.
No. 58, No. 58-212844, No. 59-19925,
59-46646, 59-109055, 6
3-53544, Japanese Patent Publication No. 36-10466, 42
No. 26187, No. 48-30492, No. 48-31
No. 255, No. 48-41572, No. 48-54965.
No. 50-10726, US Pat. No. 2,719,08
No. 6, No. 3,707,375, No. 3,754,919
No. 4,220,711 and the like.

Preferred examples of the fluorescent whitening agent that can be used in combination include coumarin type fluorescent whitening agents. Examples of these are described in JP-B-45-4699 and JP-A-54-5324.

Preferred antioxidants that can be used in combination include hindered amine antioxidants, hindered phenol antioxidants, aniline antioxidants, quinoline antioxidants and the like. Examples of these are JP-A-59
-155090, 60-107383, 60-
107384, 61-1377770, 61-13.
No. 9481, 61-160287 and the like.

The amount of the ultraviolet absorber, fluorescent whitening agent, and antioxidant that can be used in combination is 0.05 to 1.0 g / m ² ,
Particularly, 0.1 to 0.4 g / m ² is preferable.

When the recording material of the present invention is used for pressure sensitive paper, US Pat. Nos. 2,505,470 and 2,505,505 are applicable.
No. 471, No. 2,505,489, No. 2,548,3
No. 66, No. 2,712,507, No. 2,730,45
No. 6, No. 2,730,457, No. 3,103,404
Various forms can be adopted as described in the prior patents such as No. 3,418,250, and No. 4,010,038. Most commonly it consists of at least a pair of sheets containing separately an electron-donating colorless dye and an electron-accepting compound.

Regarding the method for producing capsules, a method utilizing coacervation of a hydrophilic colloid sol described in US Pat. Nos. 2,800,457 and 2,800,458, and US Pat. No. 3,287,154. British patent 8
67,797, 950,443, 989,26
No. 4, No. 990,443, No. 1,091,076,
Japanese Examined Patent Publication No. 38-19574, No. 42-446, No. 42
Interfacial polymerization method described in US Pat.
Methods by precipitation of polymers described in U.S. Pat. No. 4,418,250 and U.S. Pat. No. 3,418,2.
A method using the isocyanate polyol wall material described in US Pat. No. 50, a method using the isocyanate wall material described in US Pat. No. 3,914,511, US Pat.
01,140, 4,087,376, 4,08
Urea-formaldehyde system described in No. 9,802,
Urea-formaldehyde-resorcinol-based wall material, melamine-formaldehyde resin, hydroxypropyl-pill cellulose, and other wall-forming materials, JP-B-36-9168 and JP-A-51-9079. -Situ, British patent 9
52,807 and 965,074, the electrolytic dispersion cooling method, US Pat. No. 3,111,407, and British Patent 930,422 include the spray drying method. Although not limited thereto, it is preferable to form a polymer film as a microcapsule wall after emulsifying the core substance.

Generally, an electron-donating colorless dye is used as a solvent (synthetic oil such as alkylated naphthalene, alkylated diphenyl, alkylated diphenylmethane, alkylated terphenyl, and chlorinated paraffin): vegetable oil such as cotton oil and castor oil. : Animal oil: Mineral oil or mixtures thereof)
Dissolve in the microcapsules contained in paper,
A color former sheet is obtained by applying it to high-quality paper, plastic sheet, resin-coated paper, or the like. Further, the electron-accepting compound and, if necessary, additives are dispersed alone or in a mixture in a binder such as styrene-butadiene latex or polyvinyl alcohol to form a support such as paper, plastic sheet, resin coated paper together with a pigment. A developer sheet is obtained by applying.

As a binder, it is preferable to use a carboxy-modified styrene-butadiene latex in combination with a water-soluble polymer from the viewpoint of light resistance and water resistance. Further, as the pigment, it is preferable to use calcium carbonate having an average particle diameter of 5.0 μm or less in an amount of 60% by weight or more based on all pigments from the viewpoint of color developing ability.
The amount of the electron-donating colorless dye and the electron-accepting compound used depends on the desired coating thickness, the form of the pressure-sensitive recording paper, the capsule manufacturing method, and other conditions, and may be appropriately selected according to the conditions. A person skilled in the art can easily determine this usage amount.

When it is used for thermal paper, it is disclosed in JP-A-62-1.
44,989, JP-A-1-87291, and the like. Specifically, the electron-donating colorless dye and the electron-accepting compound are 10 μm in the dispersion medium.
Hereinafter, it is preferably used by pulverizing and dispersing to a particle size of 3 μm or less. As the dispersion medium, a water-soluble polymer aqueous solution having a concentration of about 0.5 to 10% is generally used, and dispersion is performed by a ball mill,
It is carried out by using a sand mill, a horizontal sand mill, an attritor, a colloidal mill or the like.

At that time, a thermofusible substance may be contained in the thermosensitive coloring layer in order to improve the thermal response. Typical examples of the heat-fusible substance include aromatic ethers, thioethers, esters and / or aliphatic amides or ureides. Examples of these are disclosed in JP-A-58-57989 and JP-A-5-57989.
8-87094, 61-58789, 62-1
09681, 62-2132674, 63-15
No. 1478, No. 63-235961, JP-A 2-18
No. 4489 and No. 2-215585.

These are used at the same time as the electron-donating colorless dye or at the same time as being finely dispersed at the same time as the electron-accepting compound. 20% or more and 30% of the amount of these used and the electron-accepting compound
It is added in a weight ratio of 0% or less, especially 40% or more and 150%
The following are preferred. Additives may be added to the thus obtained coating liquid as needed to further satisfy various requirements. As an example of the additive, in order to prevent the recording head from being soiled during recording, an oil-absorbing substance such as an inorganic pigment or polyurea filler is dispersed in the binder to further improve the releasability of the head. Therefore, fatty acids and metal soaps are added. So in general,
In addition to electron-donating colorless dyes and electron-accepting compounds that directly contribute to color development, heat-fusible substances, pigments, waxes, antistatic agents, ultraviolet absorbers, defoamers, conductive agents, fluorescent dyes, surfactants Additives such as are coated on the support to form the recording material. Further, if necessary, a protective layer may be provided on the surface of the heat-sensitive recording layer.

Usually, the electron-donating colorless dye and the electron-accepting compound are dispersed and applied in a binder. Water-soluble binders are generally used, and polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, epichlorohydrin-modified polyamide, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer, isobutylene-anhydrous. Examples thereof include maleic salicylic acid copolymer, polyacrylic acid, polyacrylic acid amide, methylol-modified polyacrylamide, starch derivative, casein, gelatin and the like. Further, a water-proofing agent may be added to these binders for the purpose of imparting water resistance, or an emulsion of a hydrophobic polymer, specifically, a styrene-butadiene rubber latex, an acrylic resin emulsion or the like may be added. The amount of these used is preferably 0.4 to 5 g / m ² , more preferably 0.8
˜1.6 g / m ² is preferred.

The obtained heat-sensitive coating liquid is applied to high-quality paper, high-quality paper having an undercoat layer, synthetic paper, plastic film and the like. At this time, it is particularly preferable from the viewpoint of dot reproducibility to use a support having a smoothness of 500 seconds or more, particularly 800 seconds or more as defined by JIS-8119.

In the recording material of the present invention, known wax, antistatic agent, defoaming agent, conductive agent, and
Various additives such as fluorescent dyes, surfactants, and ultraviolet absorber precursors can be used.

In the recording material of the present invention, a protective layer may be provided on the surface of the recording layer, if necessary. Two or more protective layers may be laminated if necessary. Materials used for the protective layer include polyvinyl alcohol, carboxy-modified polyvinyl alcohol, vinyl acetate-acrylamide copolymer, silicon-modified polyvinyl alcohol, starch, modified starch, methyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, gelatins, gum arabic, casein, Styrene-maleic acid copolymer hydrolyzate, styrene-maleic acid copolymer half ester hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyacrylamide derivative, polyvinylpyrrolidone, sodium polystyrene sulfonate, sodium alginate Water-soluble polymer compounds such as styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex,
Latexes such as methyl acrylate-butadiene rubber latex and vinyl acetate emulsion are used. The water-soluble polymer compound in the protective layer can be crosslinked to further improve the storage stability, and a known crosslinking agent can be used as the crosslinking agent. Specifically, water-soluble initial condensates such as N-methylol urea, N-methylol melamine, and urea-formalin, dialdehyde compounds such as glyoxal and glutaraldehyde, inorganic cross-linking agents such as boric acid and borax, polyamide epichlorohydrin, etc. Can be mentioned. Further, known pigments, metal soaps, waxes, surfactants and the like can be used in the protective layer. The coating amount of the protective layer is preferably 0.2 to 5 g / m ² , more preferably 0.
5 to ² g / m ² is preferable. The film thickness is 0.2 to 5
μm is preferable, and 0.5 to 2 μm is particularly preferable.

When a protective layer is used in the recording material of the present invention, the protective layer may contain a known UV absorber or its precursor.

As the support that can be used in the recording material of the present invention, acid paper, neutral paper, coated paper, plastic film laminated paper, synthetic paper, plastic film and the like can be used. Further, these supports may be provided with a known undercoat layer. This undercoat layer can be provided in the same manner as the protective layer.

A back coat layer may be provided for the purpose of correcting the curl balance of the support or improving the chemical resistance from the back side, and a label may be provided by combining a release paper on the back side with an adhesive layer. You may take the form of. This back coat layer can be provided in the same manner as the protective layer.

The indolyl azaphthalide compound of the present invention is prepared according to US Pat. Nos. 4,399,209 and 4,551,407.
Issue 4,440,846, Issue 4,536,463
JP-A-63-184738, JP-A-58-88739.
No. 62-143044, JP-A-2-188293.
No. 2, No. 2-188294, No. 3-72358, No. 3-
No. 87827, No. 4-226455, No. 4-2479.
It can be applied to various recording materials described in No. 85, No. 5-124360, No. 5-294063 and the like.

The indolyl azaphthalide compound of the present invention can be used in a multicolor heat-sensitive recording material. Regarding this multicolor heat-sensitive recording material (light-sensitive heat-sensitive recording material), Japanese Patent Laid-Open No. Hei.
No. 135787, No. 4-144784, No. 4-144785, No. 4-194842,
No. 4-247447, No. 4-247448, No. 4-340540 and No. 4-340541.
No. 5-34860 and the like. Specifically, it can be obtained by laminating thermosensitive recording layers that develop different hues. The layer structure is not particularly limited, but in particular, a thermosensitive recording layer 2 in which two types of diazonium salt compounds having different photosensitizing wavelengths are combined with respective diazonium salt compounds to combine with a coupler capable of developing a different hue A multicolor heat-sensitive recording material in which a layer and a heat-sensitive recording layer in which an electron-donating colorless dye and an electron-accepting compound are combined are laminated is preferable. That is, a first heat-sensitive recording layer containing an electron-donating colorless dye and an electron-accepting compound on a support,
A second heat-sensitive recording layer containing a diazonium salt compound having a maximum absorption wavelength of 360 nm ± 20 nm and a coupler that reacts with the diazonium salt compound to produce a color when heated, a diazonium salt compound having a maximum absorption wavelength of 400 ± 20 nm and the diazonium The third heat-sensitive recording layer contains a coupler that develops a color by reacting with a salt compound when heated. In this example, the coloring hue of each thermosensitive recording layer is set to 3 in the subtractive mixing.
Full-color image recording is possible by selecting primary colors, yellow, magenta, and cyan.

In the recording method of this multicolor heat-sensitive recording material, first, the third heat-sensitive recording layer is heated to cause the diazonium salt and the coupler contained in the layer to develop color. Next 400 ± 20 nm
Is irradiated to decompose the unreacted diazonium salt compound contained in the third thermosensitive recording layer, and then the second thermosensitive recording layer is provided with sufficient heat to develop a color. The colored diazonium salt compound and the coupler are colored.
At this time, the third thermosensitive recording layer is also heated at the same time, but since the diazonium salt compound has already been decomposed and the coloring ability has been lost, no coloring occurs. Further, light of 360 ± 20 nm is irradiated to decompose the diazonium salt compound contained in the second thermosensitive recording layer, and finally, sufficient heat for color development of the first thermosensitive recording layer is applied to cause color development. At this time, the third and second
The heat-sensitive recording layer is also heated strongly at the same time, but since the diazonium salt compound has already been decomposed and the coloring ability is lost, it does not develop color.

When the recording material of the present invention is a multicolor thermosensitive recording material, an intermediate layer may be provided in order to prevent color mixing between the thermosensitive recording layers. This intermediate layer is made of a water-soluble polymer compound such as gelatin, phthalated gelatin, polyvinyl alcohol and polyvinylpyrrolidone, and may contain various additives as appropriate. The coating amount is preferably from 2 to 10 g / m ^2, more preferably 4-5 g / m ^2. The film thickness is preferably 0.5 to 10 μm.

[0039]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto. In the examples, unless otherwise specified, weight% is expressed.

[0040]

[Example 1]

Synthesis of Inventive Compound Example 1 N, N-di-n-propyl-m-toluidine 19.1 g
And (1-ethyl-2-methylindol-3-yl)
(3-Carboxyridin-2-yl) ketone 30.8
g was stirred in 38 ml of acetic anhydride at 50 to 55 ° C. for 3 to 4 hours. The reaction solution was cooled to 10 ° C., and the precipitated crystal was filtered. The obtained crystals were recrystallized from ethyl acetate-isopropanol to obtain 37.8 g of Compound 1 of the present invention as pale yellow crystals. ¹ H-NMR (CDCl ₃ ) δ (TMS, ppm)
0.92. (6H, t), 1.29 (3H, t), 1.
59 (4H, qn), 2.17 (3H, s), 2.18
(3H, s), 3.22 (4H, t), 4.08 (2
H, qr), 6.33 (1H, dd), 6.47 (1
H, dd), 6.94 (1H, t), 7.05 (1H,
d), 7.08 (1H, t), 7.23 (1H, d),
7.29 (1H, d), 7.38 (1H, dd), 8.
18 (1H, dd), 8.84 (1H, dd)

Example 2 1) Preparation of Electron-Donating Dye Precursor Capsule Solution 3.0 parts of electron-donating colorless dye (Compound Example 2 of the present invention) was dissolved in 20 parts of ethyl acetate, and further dissolved in a high-boiling solvent. Alkylnaphthalene (KMC-210, manufactured by Kureha Chemical Industry Co., Ltd.)
20 parts were added and mixed uniformly. In the obtained mixed liquid,
As a capsule wall material, 20 parts of a 3/1 adduct of xylylene diisocyanate / trimethylolpropane (75 wt% ethyl acetate solution) (Takenate D-110N (manufactured by Takeda Pharmaceutical Co., Ltd.)) was added and stirred uniformly. .

Separately, polyvinyl alcohol (polymerization degree: 17
00, saponification degree 88%) 54% 6% aqueous solution was prepared, and the above-mentioned electron-donating dye precursor was added thereto, followed by emulsification and dispersion with a homogenizer. 68 parts of water was added to the obtained emulsion for homogenization, the temperature was raised to 50 ° C. with stirring, and the encapsulation reaction was carried out for 3 hours to obtain the target capsule solution.
The average particle size of the capsule was 1.6 μm.

2) Preparation of Electron Accepting Compound Dispersion After adding 30 parts of bisphenol A as an electron accepting compound to 150 parts of a 4% aqueous solution of polyvinyl alcohol,
A ball mill was used for dispersion for 24 hours to prepare a dispersion liquid. The average particle size of the electron-accepting compound in the obtained dispersion is 1.2.
μm. 3) Preparation of coated paper and image recording The above-mentioned electron-donating dye precursor capsule liquid and electron-accepting compound dispersion liquid were mixed so that the molar ratio of electron-donating dye precursor / electron-accepting compound was 1/15. Thus, the intended coating liquid was prepared. Apply the above coating solution with a Meyer bar on a polyethylene terephthalate support having a thickness of 75 μm.
It was dried to obtain the desired heat-sensitive recording material. The color density was printed with a Kyocera printing tester to obtain a cyan image.

4) Evaluation of Performance of Recording Paper (Coloring Density) The image density D ₀ of the coloring portion was measured with a Macbeth densitometer. The higher this value, the higher the sensitivity of the thermal recording paper. (Lightfastness test of image part) For the image part obtained by printing,
Xenon Fade Meter (FAL-25AX-HC
Image density D ₁ after 48 hours of light irradiation was measured with a Macbeth reflection densitometer. The light resistance of the image area is determined by the residual rate of the image after light irradiation = (D ₁ / D ₀ ) × 10.
0% is shown as a standard. The higher the residual rate, the better the light resistance of the image area. (Light resistance test of non-image area)
Xenon Fade Meter (FAL-25AX-HC
The mold, manufactured by Suga Test Instruments Co., Ltd.) was irradiated for 48 hours. The yellow density Y ₀ of the non-image area before light irradiation and the yellow density Y ₁ of the non-image area after light irradiation were measured with a Macbeth densitometer.
The light resistance of the non-image area is determined by the extension of yellow density (ΔOD _y ) =
The (Y ₁ -Y ₀₎ shown as a guide. It is shown that the smaller ΔOD _y is, the more excellent the light resistance of the non-image portion is.

[Examples 3 to 5] The electron-donating colorless dye of Example 2 (inventive compound example 2) was replaced with invented compound example 3 (example 3), invented compound example 4 (example 4), and A thermosensitive recording paper was obtained in the same manner as in Example 2 except that the invention compound example 5 (Example 5) was used. Image recording and recording paper performance evaluation were performed in the same manner as in Example 2.

Comparative Examples 1 to 5 The electron-donating colorless dye of Example 2 (Compound Example 1 of the present invention) was used as 3- (4-dimethylamino-2-methylphenyl) -3- (1-ethyl-2-). Methylindol-3-yl) -4-azaphthalide (Comparative Example 1), 3- (4-diethylamino-2-methylphenyl) -3- (1-ethyl-2-methylindol-3-
Yl) -4-azaphthalide (Comparative Example 2), 3- (4-di-N-β-methoxyethyl-N-ethylamino-2-methylphenyl) -3- (1-ethyl-2-methylindole-3) -Yl) -4-azaphthalide (Comparative Example 3), 3
-(4-Diethylamino-2-methylphenyl) -3-
(1-n-Pentyl-2-methylindol-3-yl) -4-azaphthalide (Comparative Example 4), 3- (4-diethylamino-2-methylphenyl) -3- (1-ethyl-2-phenylindole) A thermosensitive recording paper was obtained in the same manner as in Example 2 except that it was changed to -3-yl) -4-azaphthalide (Comparative Example 5). Image recording and recording paper performance evaluation were performed in the same manner as in Example 2.

[Examples 6 to 11] Bisphenol A, which is the electron-accepting compound of Example 2, was converted into 4,4'-cyclohexylidene diphenol (Example 6) and 4,4'-dihydroxydiphenyl sulfide (Example 7). ), 4, 4 '
-Dihydroxydiphenyl ether (Example 8), 4-
Hydroxyphenyl-4′-isopropoxyphenyl sulfone (Example 9), α, α′-bis (3,5-dihydroxyphenylcarbonyloxy) -p-xylene (Example 10), 1,3,3,5- A thermosensitive recording paper was obtained in the same manner as in Example 2 except that tetra (4-hydroxyphenyl) pentane (Example 11) was used. Image recording and recording paper performance evaluation were performed in the same manner as in Example 2.

Comparative Examples 6 to 11 The electron-donating colorless dye (Compound Example 1 of the present invention) used in Examples 6 to 11 was 3- (4-diethylamino-2-methylphenyl) -3, respectively.
-(1-Ethyl-2-methylindol-3-yl)-
Thermal recording papers were obtained in the same manner as in Examples 6 to 11 except that 4-azaphthalide was used. Image recording and recording paper performance evaluation were performed in the same manner as in Example 2.

The results of Examples 2-11 and Comparative Examples 1-11 are shown in Tables 1 and 2.

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

According to the present invention, it is possible to obtain a recording material which gives a blue to cyan image of good density, has good fastness to light and heat in the image area, and has little light stain in the white area.

Claims (2)

[Claims] 1. 3- (4-di-) represented by the general formula (I).
n-Propylamino-2-methylphenyl) -3- (1
-Alkyl-2-methylindol-3-yl) -4-
Azaphthalide compound. General formula (I) In the above formula, R represents an alkyl group having 1 to 10 carbon atoms. 2. A recording material using an electron-donating colorless dye and an electron-accepting compound, wherein 3- (4-di-n-propylamino-2-methylphenyl) -3 represented by the general formula (I) is used. -(1-Alkyl-2-methylindole-3
-Yl) -4-Azaphthalide compound-containing recording material. General formula (I) In the above formula, R represents an alkyl group having 1 to 10 carbon atoms.