JPH05148268A - Crystal of fluoran compound, production of the same crystal and recording material containing the same crystal - Google Patents

Abstract

PURPOSE:To obtain a crystal of the subject compound capable of improving solubility in capsule oils and performance of heat-sensitive recording sheets such as preservation stability or coloring characteristics. CONSTITUTION:A crystal of a compound expressed by formula I [R<1> is i-C3H7, sec-C4H9), e.g. 3-N-isopropyl-N-propylamino-6-methyl-7-anilinofluoran. The crystal of the compound expressed by formula I is obtained by reacting, e.g. a compound expressed by formula II (R2 is same as R) with a compound expressed by formula III (R3 is 1-4C alkyl) in the presence of a dehydration condensing agent containing concentrated sulfuric acid or fuming sulfuric acid added thereto at 0-100 deg.C (preferably 0-50 deg.C), then regulating the resultant compound to pH 9-12 with potassium hydroxide, etc., treating the regulated compound with an alkali at 0-100 deg.C and subsequently separating and isolating the objective compound with an organic solvent having <=50wt.% moisture content.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluoran compound useful as a color-forming compound used in recording materials such as pressure-sensitive recording materials and heat-sensitive recording materials, and more specifically, crystals of the fluoran compound and a method for producing the crystals. And a recording material containing the crystal.

[0002]

2. Description of the Related Art Conventionally, a color reaction between a colorless or light-colored electron-donating compound (color-forming compound) and an organic or inorganic electron-accepting substance (developing agent) has been used to generate pressure, heat or electricity. As a method of recording information transmitted through the medium of external energy, there are pressure-sensitive recording, heat-sensitive recording, electric conduction heat-sensitive recording, and the like. A fluoran compound is widely used as a color-forming compound in these recording methods.

Conventionally, as the fluoran compound, for example, compounds of the formula (A), the formula (B) and the formula (C) are known.

[Chemical 6]

[Chemical 7]

[Chemical 8]

However, the compound of the formula (A) has a drawback that its solubility in capsule oil is extremely low when it is used as a pressure-sensitive recording material, and when it is used as a heat-sensitive recording material, for example, bisphenol A and the like. When it is mixed with the above-mentioned color developer, it is colored gray or black gray itself, and when it is applied to paper, there is a drawback that only paper colored gray (black background) is obtained. Also,
The compound of the formula (B) has a color development temperature that is too high for use as a heat-sensitive recording material, and thus cannot be said to have sufficient performance to meet the demand for higher-speed and higher-density recording at present. There is a strong demand for a color-forming compound that rapidly develops color at low temperatures.

Further, the compounds of the formulas (B) and (C) also have low solubility in capsule oil, and it cannot be said that they have sufficient performance for use in pressure-sensitive recording materials. General formula (1)

[Chemical 9] With respect to the fluoran compound represented by, for example, a compound in which R ₁ is i-C ₃ H ₇ group [compound of formula (1-a)] and a compound in which R ₁ is sec-C ₄ H ₉ group [formula ( 1-b)] is disclosed in JP-A-60-47068.

[Chemical 10]

[Chemical 11]

In the above-mentioned JP-A-60-47068, the fluoran compound represented by the formula (D) is described.

[Chemical 12] Although specifically described, the compound of formula (D) obtained by precipitating the fluorane compound of formula (D) from hydrous methanol as in the method described in this publication has a melting point of 114 to 117 ° C. And was substantially amorphous (amorphous). When the compounds of formula (1-a) and formula (1-b) are produced by a method similar to the above-mentioned method, the obtained product is amorphous (amorphous), and these compounds are used as the color-forming compound. , As a developer, for example,
When a thermal recording paper was prepared using bisphenol A, the whiteness of the uncolored part (background) was poor (background stain), which was a serious problem for practical use.

In the general formula (1), a compound in which R ₁ is i-C ₄ H ₉ group [compound of formula (1-c)] is

[Chemical 13] Although suggested in JP-A-60-141762, no specific description is given regarding the compound of formula (1-c). Furthermore, the compound obtained by precipitating the fluorane compound of the formula (1-c) from, for example, hydrous methanol is substantially amorphous (amorphous), and this amorphous is used as a color-forming compound to develop a color. When, for example, bisphenol A was used as an agent to prepare a thermal recording paper, the whiteness of the uncolored portion (background) was poor (background stain), which was a serious problem in practical use.

Formula (1-a), (1-b) or (1-
Regarding the heat-sensitive recording material using the fluoran compound of c), it is proposed in JP-A-61-74883 or JP-A-61-144387, but the fluoran compound used is amorphous (amorphous). It is not distinguished whether it is a crystal or a crystal, and it is not sufficiently disclosed. That is, the above formulas (1-a) and (1-b)
Alternatively, when a thermosensitive recording paper is prepared by using, for example, bisphenol A as a color-developing agent, using an amorphous form of the fluoran compound (1-c) as a color-developing compound, white color in the uncolored part (background) The degree was poor (ground stain), which was a serious problem for practical use.

[0009]

The object of the present invention is to improve the drawbacks of the fluoran compound represented by the general formula (1) as a color forming compound for recording materials, and to provide pressure-sensitive and heat-sensitive recording materials. To provide a crystal of a fluorane compound represented by the general formula (1) having excellent properties as a color-forming compound for a recording material such as a recording material, and a method for producing the crystal and a recording material containing the crystal. Is to provide.

[0010]

Means for Solving the Problems The inventors of the present invention have made diligent studies on the compound represented by the general formula (1) in order to improve the above-mentioned drawbacks. As a result, the compound represented by the general formula (1) is obtained. Completes the present invention by discovering the existence of a conventionally unknown crystal, finding that this crystal has excellent performance as a color-forming compound for pressure-sensitive and heat-sensitive recording materials, and a method for producing this crystal. Came to.

That is, the present invention has the general formula (1)

[Chemical 14] (In the formula, R ₁ is i-C ₃ H ₇ group, sec-C ₄ H ₉ group or i-C ₄ H _{9 group.}
A group of fluorane compounds represented by
A method for producing the crystal, and a recording material containing the crystal.

The fluoran compound represented by the general formula (1) of the present invention is specifically a compound represented by the formulas (1-a), (1-b) and (1-c).

[Chemical 15]

[Chemical 16]

[Chemical 17] The fluoran compound represented by formula (1-a), formula (1-b) or (1-c) has the general formula (2):

[Chemical 18] (In the formula, R ₂ is i-C ₃ H ₇ group, sec-C ₄ H ₉ group or i-C ₄ H _{9 group.}
A benzoic acid derivative represented by a group), more specifically, a compound represented by the formula (2-a), (2-b) or (2-c):

[Chemical 19]

[Chemical 20]

[Chemical 21] General formula (3)

[Chemical formula 22] (In the formula, R ₃ represents a lower alkyl group having 1 to 4 carbon atoms)
The diphenylamine derivative represented by, for example, is preferably reacted in concentrated sulfuric acid in the presence of a dehydrating condensing agent such as concentrated sulfuric acid, concentrated sulfuric acid added with fuming sulfuric acid, polyphosphoric acid, phosphorus pentoxide, and anhydrous aluminum chloride. And then made alkaline.

The dehydration condensation reaction is usually carried out at a reaction temperature of 0 to 100 ° C. for several hours to 100 hours. The reaction temperature is particularly preferably 0 to 50 ° C., particularly when the reaction is carried out in concentrated sulfuric acid. Since the reaction time depends on the reaction temperature, a sufficient time is spent for the reaction. Further, after dehydration condensation, the alkali treatment usually carried out is potassium hydroxide water,
Adjust the pH to 9-12 with sodium hydroxide water, etc.
It is preferably carried out in the temperature range of 00 ° C. At this time, the alkali treatment may be performed in the coexistence of an organic solvent other than water, such as benzene and toluene.

Crystals of the fluorane compound of the present invention are obtained by subjecting the product obtained by the above reaction to aromatic hydrocarbon solvents such as benzene, toluene and xylene, alcohol solvents such as methanol, ethanol, isopropanol and n-butanol. , Or a polar solvent such as acetonitrile or dimethylformamide, or a mixture thereof in the form of crystals, which can then be isolated as stable crystals. In addition, among the above solvents, an alcohol solvent or a polar solvent may be used as a mixed solvent with water. In this case, the water content is preferably 50% by weight or less, more preferably 30% by weight or less, and further preferably 10% by weight or less. If the water content exceeds 50% by weight, amorphous (amorphous) precipitates and it becomes difficult to isolate stable crystals.

As a method of precipitating crystals, a method of once completely dissolving a fluoran compound in a solvent and then cooling and precipitating is often used. At this time, if necessary, the fluoran compound may be completely dissolved by heating at room temperature or higher and within the boiling point range of the solvent.
After complete dissolution, crystals are precipitated by stirring or standing still. The precipitated crystal can be isolated by a known method, for example, a method by filtration, without any special method. After isolation, if necessary, an operation of washing or redissolving with an organic solvent having a water content of 50% by weight or less (for example, the above-mentioned organic solvent) and then precipitating it as crystals may be performed. After the isolation, the crystals of the fluoran compound can be obtained by drying by a usual method.

In producing the compound of the general formula (1), the compound of the general formula (2) and the compound of the general formula (3) are subjected to a dehydration condensation reaction in the presence of a dehydration condensation agent (for example, concentrated sulfuric acid). After that, when the alkali treatment with alkaline water is performed in the coexistence of a substantially water-insoluble organic solvent such as benzene and toluene, the generated fluorane compound of the general formula (1) is dissolved in the organic solvent. Therefore, when such an alkali treatment is performed, the crystals of the fluorane compound represented by the general formula (1) of the present invention have the following properties:
It can also be suitably isolated by precipitating it as crystals from an organic solvent solution containing this fluoran compound.

The crystal of the fluorane compound represented by the general formula (1) of the present invention, which is preferably produced by the above method, will be described in detail. In the general formula (1), R ₁ is i
The compound which is a —C ₃ H ₇ group, the crystal of the formula (1-a) is Cu—
Diffraction angle (2θ) 16.4 ° in X-ray diffraction method using Kα rays
It is a crystal characterized by an X-ray diffractogram showing strong peaks at 16.2 °, 19.6 ° and 22.4 °. The powder X-ray diffraction pattern is shown in FIG. General formula (1)
In the compound of formula (1-, wherein R ₁ is a sec-C ₄ H ₉ group,
The crystal of b) has a strong peak at a diffraction angle (2θ) of 21.9 ° in the X-ray diffraction method using Cu-Kα ray, 16.1 ° and 16.4 °.
It is a crystal characterized by an X-ray diffractogram showing a relatively strong peak at °. The powder X-ray diffraction pattern is shown in FIG.
Further, in the general formula (1), a compound in which R ₁ is an i-C ₄ H ₉ group, the crystal of the formula (1-c) has a diffraction angle (2θ) of 15.7 ° and an X-ray diffraction method of Cu-Kα ray. A crystal characterized by an X-ray diffractogram showing strong peaks at 22.1 ° and relatively strong peaks at 19.2 °, 19.7 ° and 20.1 °. The powder X-ray diffraction pattern is shown in FIG.

The compounds of formulas (1-a), (1-b) and (1-c) prepared by the method described in JP-A-60-47068 as a method for preparing a compound of formula (D). The powder X-ray diffraction patterns of the compound by Cu-Kα ray are shown in FIGS. 4 and 5.
And FIG. 6 respectively. As shown in the X-ray diffraction pattern, these compounds are substantially amorphous with low crystallinity.

Further, the crystal of the fluorane compound represented by the general formula (1) of the present invention can be suitably produced from the above-mentioned amorphous (amorphous) compound represented by the general formula (1). .. That is, amorphous (amorphous)
The water content of the compound of general formula (1) is 50% by weight
It can also be suitably produced by dissolving it in an organic solvent having a water content of preferably 10% by weight or less, then precipitating it as crystals and isolating it.

The crystal of the fluorane compound represented by the general formula (1) of the present invention produced as described above can be used as a color-forming compound in various recording materials. The recording material of the present invention is a pressure-sensitive recording material or a heat-sensitive recording material. The crystal of the fluorane compound represented by the general formula (1) of the present invention may be used alone or, for example, in order to adjust the hue of color development, another color-forming compound such as triphenylmethane may be used. Lactones, fluorans,
Color-forming compounds such as spiropyrans can be mixed and used as desired.

That is, when the crystal of the fluoran compound represented by the general formula (1) is used as, for example, a pressure-sensitive recording material, it is a solvent commonly used in this field, for example,
Alkylbenzene type (n-dodecylbenzene etc.), Alkylbiphenyl type (triethylbiphenyl, diisopropyldiphenyl etc.), Hydrogenated terphenyl type, Alkylnaphthalene type (Diisopropylnaphthalene etc.), Diarylethane type (Phenylxylylethane, Styrenated ethylbenzene etc.) ), Or a chlorinated paraffin-based solvent alone or in a mixed solvent, and the solution is subjected to gelatin, melamine-aldehyde, or urea-aldehyde resin, polyurethane, or poly (ether) by a method such as a coacervation method or an interfacial polymerization method. It is enclosed in microcapsules having a partition wall of urea, polyamide, etc., and the aqueous dispersion of the obtained capsules together with a suitable binder (eg starch paste, latex etc.) etc., a suitable support (eg paper, plastic). Sheet, resin-coated paper, etc.) Coated, as a sheet for the upper pressure-sensitive recording it can be used. Of course, the above-mentioned capsule dispersion liquid is applied to one surface of the support, and the developer coating liquid mainly containing the developer is applied to the opposite surface, so-called intermediate sheet,
Furthermore, a coating liquid in which the capsule and the color developer are mixed is applied to the same surface of the support, or a capsule dispersion liquid is applied.
It can also be used for so-called single copy sheets.

In this case, as the developer, a copolymer of salicylic acid, phenols and aldehydes (eg formaldehyde), substituted salicylic acid (alkyl substitution,
A very large number of aryl-substituted or aralkyl-substituted compounds are known, for example, 3,5-di-α-methylbenzylsalicylic acid), a co-condensation resin of substituted salicylic acid and styrene,
Alkylphenols (eg, octylphenol), phenol-aldehyde resins (eg, p-phenylphenol novolac resins) or metal salts thereof (eg, metal salts such as zinc, magnesium, aluminum, calcium, tin and nickel), and further Activated clay can be mentioned.

When the heat-sensitive recording material is used, crystals of the fluorane compound represented by the general formula (1) and a developer (for example, bisphenol A or a halide or alkyl compound thereof, dihydroxydiphenyl sulfone or a halide or alkyl compound thereof). Compounds, phenols such as hydroxybenzoic acid esters and hydroquinone monoethers, organic developers such as salicylic acid derivatives, salicylic acid amide derivatives, urea derivatives and thiourea derivatives, or acid clay, attapulgite, activated clay, chloride Inorganic developer such as aluminum and zinc bromide)
In a fine aqueous dispersion of a binder (for example, polyvinyl alcohol or a modified product thereof, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, gum arabic, a salt of styrene-maleic anhydride copolymer, or isobutylene-acrylic acid-maleic anhydride). Copolymers, etc.), pigments (talc, kaolin, calcium carbonate, etc.) and, if necessary, sensitizers (higher fatty acid amides, aromatic carboxylic acid or sulfonic acid esters, aromatic or aromatic compounds). Group-substituted aliphatic ethers, generally known sensitizers for heat-sensitive recording materials such as aromatic or aromatic group-substituted aliphatic hydrocarbons, and other additives (for example,
It can be used as a heat-sensitive recording material by adding a UV absorber, a defoaming agent, etc.) to form a fine dispersion and coating it on a suitable support (eg, paper, plastic sheet, resin-coated paper, etc.) .. Of course, it can be used without problems in a system using a solvent instead of an aqueous dispersion system. It can also be used for applications using other color forming compounds (for example, temperature indicating materials).

[0024]

When the crystal of the fluoran compound of the present invention is used in a pressure-sensitive recording material, it has a high solubility in capsule oil, which is an important property strongly desired for a color-forming compound for a pressure-sensitive recording material, and a color-developing property. The weatherability of the subsequent color image is excellent. That is, the results of comparing the solubility of the crystals of the present invention in commercially available capsule oils with the fluoran compounds of the formulas (A), (B) and (C) are as shown in Table 1. Solubility is 5% by weight of each compound in each oil.
The presence or absence of crystal precipitation after storage for 1 week was shown.

[Table 1] Incidentally, SAS-296 is manufactured by Nippon Petrochemical Co., Ltd., KMC-11.
3 is a capsule oil manufactured by Kureha Chemical. As is clear from Table 1, the crystals of the present invention have higher solubility in each oil than the fluoran compounds of the formulas (A), (B) and (C). This means that during the production of the pressure-sensitive recording material, there is no crystal precipitation during storage in capsule oil, and there is no risk of crystal precipitation in the microcapsules after microencapsulation. This is a great feature of crystals.

When crystals of the fluorane compound represented by the general formula (1) of the present invention are used in a heat-sensitive recording material, the amorphous formulas (1-a), (1-b) and (1) are used. As compared with the case of using the compound of -c), a thermal paper having high whiteness and free from background stain can be obtained. That is, crystals of the fluorane compound represented by the formulas (1-a), (1-b) and (1-c) of the present invention are used as the color forming compound, and bisphenol A is used as the color developing agent. A thermal recording paper was prepared. On the other hand, for comparison, the amorphous formulas (1-a), (1-b), and (1-
A thermal recording paper was prepared using the fluoran compound of c) and bisphenol A as a color developing agent.

Table 2 shows the results of comparing the whiteness of the background of the uncolored portions of these thermal recording papers.

[Table 2] The whiteness of the background of the uncolored part of the thermal paper is judged by visual observation, and ∘ indicates a non-colored (no background stain) high thermal paper. X indicates a thermal paper having a low whiteness that is colored black gray (ground stain). As is clear from Table 2, when the crystal of the fluorane compound represented by the general formula (1) of the present invention is used in a heat-sensitive recording material, it is possible to obtain an amorphous (amorphous) compound of the fluorane compound represented by the general formula (1). A thermal paper with a high degree of whiteness, which is free of background stains, can be obtained as compared with the above.

Further, when the crystal of the fluorane compound represented by the general formula (1) of the present invention is used in a heat-sensitive recording material,
Compared to the case of using the conventionally known compound of formula (A) or (B), the compound of the present invention is extremely excellent at the present time when a color is rapidly developed at a lower temperature and a high speed and high density recording material is desired. It can be said that it is a color forming compound having excellent performance.
That is, in the crystal of the compound represented by the general formula (1) of the present invention as the color forming compound, for example, the compound of the formula (1-a) in which R ₁ is i-C ₃ H ₇ group and R ₁ are The results of measuring the color density characteristics with respect to temperature of the thermosensitive recording paper prepared by using bisphenol A as a color developer by using each crystal of the compound of formula (1-c) having i-C ₄ H ₉ group are shown. 7 shows. The color density is Macbeth reflection densitometer (TR-5
24 type). The larger the value is, the darker the color is.

FIG. 7 shows the color-developing characteristics of the crystals of the fluorane compound of the present invention with respect to temperature, and the color-developing characteristics with respect to temperature of the compounds of formulas (A) and (B) as comparative examples. As is clear from FIG. 7, the crystal of the fluoran compound of the present invention has an excellent feature that it develops color rapidly at a lower temperature than the compounds of the formulas (A) and (B). The compound represented by the general formula (1) of the present invention is
Although it differs from the known fluorane compounds represented by the formulas (A), (B) and (C) only in the substituent on the amino group at the 3-position in the fluorane structure, as described above, The crystal of the fluoran compound represented by the general formula (1) has very excellent characteristics as a color-forming compound, such as solubility in capsule oils and color-forming property by heat, as compared with the above-mentioned known compounds. .. Further, the crystal of the fluorane compound represented by the general formula (1) of the present invention has a coloring property for a recording material, as compared with the amorphous form of the fluorane compound represented by the general formula (1). It has very excellent characteristics as a compound.

[0029]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Example 1 [Production of Crystal of Compound (1-a) in which R ₁ is i-C ₃ H ₇ Group in General Formula (1)] 2- (4′-N-isopropyl-Nn-propylamino-2 '-Hydroxybenzoyl) benzoic acid [compound of formula (2-a)] 10
After dissolving 8 g in 350 ml of 96% concentrated sulfuric acid at 10 ° C, 4-methoxy-2-
69 g of methyldiphenylamine [a compound in which R ₃ is a methyl group in the general formula (3)] was added at the same temperature, and the temperature was 10 to 15 ° C.
It was stirred for 24 hours. The reaction mixture was discharged into 3500 ml of ice water, the precipitated solid was collected, washed with water, and the solid was washed with 10% NaOH.
After adding in 1000 ml of water and further adding 700 ml of toluene,
The mixture was stirred at 60 to 70 ° C for 2 hours. After the toluene layer was separated, it was washed with warm water until it became neutral, the toluene layer was separated and taken out, and toluene was concentrated under reduced pressure at 40 ° C., and the precipitated crystals were filtered. After washing with a small amount of toluene, further washing with methanol and drying at 60 ° C. for 24 hours to give 3-N-isopropyl-Nn-propylamino-6-methyl-7-anilinofluorane [formula (1-a Compound of 1)] was obtained as almost colorless crystals. Melting point 192-194 [deg.] C. A toluene solution of crystals of this compound was colorless and transparent, and rapidly developed black on silica gel. The powder X-ray diffraction pattern is shown in FIG.

Example 2 [In the general formula (1), R ₁ is
Production of Crystals of Compound (1-b) Having sec-C ₄ H ₉ Group] In Example 1, instead of 2- (4′-N-isopropyl-Nn-propylamino-2′-hydroxybenzoyl) benzoic acid 2- (4'-N-sec-butyl-Nn-propylamino-2'-hydroxybenzoyl) benzoic acid [compound of formula (2-b)]
In accordance with the method described in Example 1 except that was used 3-N-sec-
Butyl-Nn-propylamino-6-methyl-7-anilinofluorane [compound of formula (1-b)] was obtained as almost colorless crystals. Melting point 190-191 [deg.] C. A toluene solution of crystals of this compound was colorless and transparent, and rapidly developed black on silica gel. The powder X-ray diffraction pattern is shown in FIG.

Example 3 [Production of Crystal of Compound (1-c) in which R ₁ is i-C ₄ H ₉ Group in General Formula (1)] In Example 1, 2- (4'-N- Instead of isopropyl-Nn-propylamino-2'-hydroxybenzoyl) benzoic acid, 2- (4'-N-isobutyl-Nn-propylamino-2'-hydroxybenzoyl) benzoic acid [of formula (2-c) Compound]
According to the method described in Example 1 except that was used, 3-N-isobutyl-Nn-propylamino-6-methyl-7-anilinofluorane [compound of formula (1-c)] was almost colorless crystals. Got as. Melting point 185-187 ° C. A toluene solution of crystals of this compound was colorless and transparent, and rapidly developed black on silica gel. The powder X-ray diffraction pattern is shown in FIG.

Comparative Example 1 [Production of compound of formula (1-a) by the method described in JP-A-60-47068] 2- (4'-N-isopropyl-Nn-propylamino-2'-hydroxybenzoyl ) Benzoic acid [compound of formula (2-a)] 1
Dissolve 6.4g in 150g of 96% concentrated sulfuric acid, then at 4-
Methoxy-2-methyldiphenylamine (10.2 g) was added and dissolved, and the mixture was stirred at the same temperature for 24 hours. The reaction mixture was poured into 800 g of ice water, the precipitate was filtered off, washed with water, and then 20m NaOH aqueous solution 150m
The mixture was added to the mixture to make it alkaline and then stirred at 60 to 70 ° C for 2 hours. The solid content is filtered, washed with water, dried, and then dissolved in ethylene glycol 30 g and 60% hydrous methanol 500 g,
The solid obtained by precipitation was collected and dried at 30 ° C. to obtain 12.0 g of 3-N-isopropyl-Nn-propylamino-6-methyl-7-anilinofluorane [compound of formula (1-a)]. Obtained as an almost colorless powder. Melting point 113-116 ° C. The obtained fluorane compound of the formula (1-a) was found to be amorphous (amorphous) by measurement of powder X-ray diffraction. The powder X-ray diffraction pattern is shown in FIG.

Comparative Example 2 [Production of compound of formula (1-b) by the method described in JP-A-60-47068] In Comparative Example 1, 2- (4'-N-isopropyl-Nn-propylamino- 2- (4'-N-sec-butyl-Nn-propylamino-2'-hydroxybenzoyl) benzoic acid [compound of formula (2-b)] was used instead of 2'-hydroxybenzoyl) benzoic acid. Otherwise, according to the method described in Comparative Example 1, 3-
N-sec-butyl-Nn-propylamino-6-methyl-7-anilinofluorane [compound of formula (1-b)] was obtained as an almost colorless powder. Melting point 114-117 ° C. The obtained fluoran compound of the formula (1-b) was found to be amorphous by powder X-ray diffraction measurement. The powder X-ray diffraction pattern is shown in FIG.

Comparative Example 3 [Production of compound of formula (1-c) by the method described in JP-A-60-47068] In Example 1, 2- (4'-N-isopropyl-Nn-propyl) Amino-2'-hydroxybenzoyl) benzoic acid was replaced with 2- (4'-N-isobutyl-Nn-propylamino-2'-hydroxybenzoyl) benzoic acid [compound of formula (2-c)] Otherwise, according to the method described in Comparative Example 1, 3-
N-isobutyl-Nn-propylamino-6-methyl-7-anilinofluorane [compound of formula (1-c)] was obtained as an almost colorless powder. Melting point 115-118 ° C. The obtained fluoran compound of the formula (1-c) was found to be amorphous by powder X-ray diffraction measurement. The powder X-ray diffraction pattern is shown in FIG.

Example 4 [Production of crystals of formula (1-a)] 10 g of the amorphous fluorane compound of formula (1-a) produced in Comparative Example 1 was added to 100 ml of isopropanol, and the mixture was heated to 60 ° C.
It was dissolved in. After cooling to room temperature, the precipitated crystals are filtered,
Drying gave 9 g of almost colorless crystals. Melting point 192-194 ° C. The powder X-ray diffraction pattern was the same as in FIG.

Example 5 [Production of Crystals of Formula (1-b)] 10 g of the amorphous fluorane compound of formula (1-b) produced in Comparative Example 2 was added to 80 ml of n-butanol, and the mixture was heated at 80 ° C. Dissolved. After cooling to room temperature, the precipitated crystals were filtered and dried to obtain 9 g of almost colorless crystals. Melting point 190-191 ° C. The powder X-ray diffraction pattern was the same as in FIG.

Example 6 [Production of crystals of formula (1-c)] 10 g of the amorphous fluorane compound of formula (1-c) produced in Comparative Example 3 was added to 100 ml of acetonitrile and dissolved at 70 ° C. .. After cooling to room temperature, the precipitated crystals were filtered and dried to obtain 9 g of almost colorless crystals. Melting point 185-187 ° C. The powder X-ray diffraction pattern was the same as in FIG.

Example 7 [Preparation of thermosensitive recording paper using crystals of fluoran compound of formula (1-a)] A mixture of 10 g of the crystals obtained in Example 1, 5 g of 10% aqueous polyvinyl alcohol solution and 37.5 g of water. Was pulverized to a particle size of 3 μ by a sand mill. On the other hand, bisphenol A was similarly dispersed to obtain a 38% developer dispersion. 65.8 g of this developer dispersion, 50 g of an aqueous dispersion of the above crystals, 18.3 g of 60% light calcium carbonate aqueous dispersion, 88 g of 10% polyvinyl alcohol aqueous solution and 51.9 g of water were mixed. This mixed solution was applied to a white base paper using a wire rod No. 10 and then air-dried at room temperature to obtain a very white thermosensitive recording paper free of background stain. Upon heating, the thermosensitive recording paper developed a slightly reddish black color very quickly. The whiteness of the background of the uncolored portion of this thermal recording paper was better than that of the thermal recording paper prepared using an amorphous type of the fluoran compound of formula (1-a) (Table 2). This thermosensitive recording paper was measured for color density characteristics with respect to temperature using a Rhodia setter. The results are shown in Fig. 7. The color density is Macbeth reflection densitometer (T
R-524 type). The larger the value, the darker the color.

Examples 8-9 Instead of using the crystal of the fluorane compound of formula (1-a) in Example 7, the crystal of the fluorane compound of formula (1-b) or the fluorane compound of formula (1-c) is used. The heat-sensitive recording paper was prepared in accordance with the method described in Example 7 except that each of the crystals was used. Upon heating, each thermal recording paper developed a slightly reddish black color very quickly. The whiteness of the background of the uncolored paper of these thermal recording papers was prepared by using the amorphous form of the fluoran compound of formula (1-b) and the amorphous form of the fluorane compound of formula (1-c), respectively. It was good as compared with the thermal recording paper (Table 2). FIG. 7 shows the results of examining the color density characteristics with respect to temperature of the thermal recording paper prepared using the crystal of the fluoran compound of formula (1-c).

Comparative Examples 4 to 6 Instead of using the crystals of the fluorane compound of the formula (1-a) in Example 7, the formula (1) prepared in Comparative Examples 1 to 3 was used.
-A), (1-b), and (1-c) were used, and a thermosensitive recording paper was prepared according to the method described in Example 7, except that the amorphous ones were used. .. In these thermal recording papers, as compared with the thermal recording papers prepared in Examples 7 to 9, the background of the paper of the uncolored part was markedly colored black gray (background stain).

Comparative Examples 7 to 8 In place of using the crystal of the fluorane compound of formula (1-a) in Example 7, 3-N, N-diethylamino-6-methyl-7-anilinofluorane [formula ( A) compounds] and 3
-N, N-di-n-butylamino-6-methyl-7-anilinofluorane [compound of formula (B)] was used in Example 7 respectively.
A thermal recording paper was prepared according to the method described in 1. The color density characteristics with respect to temperature were measured for these thermosensitive recording papers using a Rhodia setter. The results are shown in Fig. 7. The coated surface of the thermosensitive recording paper using the compound of formula (A) was slightly gray and background stain was observed.

Example 10 [Preparation of Pressure Sensitive Recording Paper Using Crystals of Fluoran Compound of Formula (1-a) of the Present Invention] Top (CB) paper and bottom (CF) paper are as follows. Manufactured. That is, 100 g of a 10% aqueous solution of ethylene-maleic anhydride copolymer and 240 g of water were mixed, and the pH was adjusted to 4.0 with a 10% aqueous sodium hydroxide solution, and the crystals obtained in Example 1 were dissolved in 5% by weight of phenyl ether. After mixing 200 g of silylethane (SAS-296 manufactured by Nippon Petrochemical Co., Ltd.) and emulsifying with a homomixer, 60 g of a methylol melamine aqueous solution (Euramine T-30 manufactured by Mitsui Toatsu Chemical Co., Ltd.) having a solid content of 50% was added and stirred to 55 The temperature was kept at 3 ° C for 3 hours to obtain a microcapsule dispersion having an average particle size of 5.0 µ. To 100 g of this microcapsule dispersion, 4.0 g of wheat starch granules, 20 g of 20% oxidized starch paste and 116 g of water were added and dispersed, and a dry coating amount of 5.5 g / m ² was applied to a quality paper of 40 g / m ^2. It was applied to obtain CB paper. on the other hand,
CF paper uses a zinc salt of a co-condensation resin of substituted salicylic acid and styrene as a developer, and in the presence of a small amount of a polymeric anionic surfactant, it is micronized in a sand gliding mill in water, and the solid content is 40% by weight. An aqueous dispersion of was obtained. Using this aqueous dispersion, make an aqueous paint (solid content 30%) with the following composition,
A CF paper was prepared by applying a dry weight of 5.5 g / m ² onto a high-quality paper weighing 40 g / m ² . When the microcapsule coated surface of the CB paper and the developer coated surface of the CF paper were superposed so as to face each other, and writing and pressing were performed, a red and black colored image was obtained on the developer coated surface. Light fastness of the color images, moisture resistance and NO _X resistance practically no problem.

Examples 11 to 12 In Example 10, the formula (1-a) obtained in Example 1 was used.
In place of the fluoran compound crystal of Formulas (1-b) and (1-c) prepared in Examples 2 and 3, respectively, except that the crystals of the formula (1-b) and (1-c) were used, respectively, according to the method described in Example 10, CB paper and CF paper were prepared, and red and black colored images were similarly obtained. The light resistance of the color image, moisture resistance, resistance to NO _X resistance was not practically problematic.

[Brief description of drawings]

FIG. 1 is an X-ray diffraction diagram of a crystal of a fluorane compound represented by the formula (1-a) produced in Example 1.

FIG. 2 is an X-ray diffraction diagram of a crystal of a fluorane compound represented by the formula (1-b) produced in Example 2.

FIG. 3 is an X-ray diffraction diagram of a crystal of a fluorane compound represented by the formula (1-c) produced in Example 3.

FIG. 4 is an X-ray diffraction diagram of an amorphous fluorane compound represented by the formula (1-a) produced in Comparative Example 1.

5 is an X-ray diffraction diagram of an amorphous fluorane compound represented by the formula (1-b) produced in Comparative Example 2. FIG.

FIG. 6 is an X-ray diffraction diagram of an amorphous fluorane compound represented by the formula (1-c) produced in Comparative Example 3. In each drawing, the horizontal axis represents the diffraction angle (2θ) and the vertical axis represents the diffraction intensity.

FIG. 7 shows crystals of the fluorane compound represented by the formulas (1-a) and (1-c) of the present invention and the formulas (A) and (B).
3 shows the color density characteristics with respect to temperature in the thermal recording paper prepared by using the known fluoran compounds represented by In the figure, curve (a) is a crystal of a compound of formula (1-a), curve (b) is a crystal of a compound of formula (1-c), curve (c) is a compound of formula (A), and curve (d). ) Indicates the color density characteristics when the compound of formula (B) is used.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI technical display location C09B 11/28 H 7375-4H (72) Inventor Kara Yoshikawa 1190, Kasama-cho, Sakae-ku, Yokohama, Kanagawa Prefecture Mitsui Toatsu Chemical Co., Ltd. (72) Inventor Akihiro Yamaguchi 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (8)

[Claims] 1. A compound represented by the general formula (1): (In the formula, R ₁ is i-C ₃ H ₇ group, sec-C ₄ H ₉ group or i-C ₄ H _{9 group.}
A group of the fluoran compound represented by the formula). 2. In the general formula (1), R ₁ is i-C ₃ H ₇
A strong peak at a diffraction angle (2θ) of 16.4 ° in the X-ray diffraction method using Cu-Kα rays, 16.2 °, 19.6 °, and
The crystal of the fluoran compound according to claim 1, characterized by an X-ray diffraction pattern showing a relatively strong peak at 22.4 °. 3. In the general formula (1), R ₁ is sec-C ₄ H ₉
The X-ray diffractogram according to claim 1, which is a base and is characterized by an X-ray diffraction diagram showing a strong peak at a diffraction angle (2θ) of 21.9 ° and a relatively strong peak at 16.1 ° and 16.4 ° in an X-ray diffraction method by Cu-Kα ray. Crystal of fluoran compound. 4. In the general formula (1), R ₁ is i-C ₄ H ₉
A strong peak at a diffraction angle (2θ) of 15.7 ° and 22.1 ° in an X-ray diffraction method using Cu-Kα ray, 19.2 °,
The crystal of the fluoran compound according to claim 1, characterized by an X-ray diffraction pattern showing relatively strong peaks at 19.7 ° and 20.1 °. 5. A compound represented by the general formula (1): (In the formula, R ₁ is i-C ₃ H ₇ group, sec-C ₄ H ₉ group or i-C ₄ H _{9 group.}
Group), which is characterized in that the compound is precipitated as a crystal from an organic solvent solution containing a fluorane compound having a water content of 50% by weight or less, and then isolated. A method for producing a crystal of the represented fluoran compound. 6. A compound represented by the general formula (1): (In the formula, R ₁ is i-C ₃ H ₇ group, sec-C ₄ H ₉ group or i-C ₄ H _{9 group.}
The amorphous fluorane compound represented by the formula (1) is dissolved in an organic solvent having a water content of 50% by weight or less, and then precipitated as crystals and isolated.
A method for producing a crystal of a fluoran compound represented by: 7. A water content ratio containing a fluoran compound
A solution of 50% by weight or less of an organic solvent contains a compound of the general formula (2) and a compound of the general formula (3): (In the formula, R ₂ is i-C ₃ H ₇ group, sec-C ₄ H ₉ group or i-C ₄ H _{9 group.}
Group) (In the formula, R ₃ represents a lower alkyl group having 1 to 4 carbon atoms) After the dehydration condensation reaction, alkali treatment is carried out in the presence of an organic solvent to obtain a fluorane compound represented by the general formula (1). The method for producing crystals of a fluorane compound according to claim 5, which is a solution of an organic solvent. 8. A recording material containing the crystal of the fluoran compound according to claim 1, 2, 3 or 4.