JP3014426B2 - Crystal of fluoran compound, method for isolating the crystal, and recording material containing the crystal - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a fluoran compound useful as a coloring compound used in recording materials such as pressure-sensitive recording materials and heat-sensitive recording materials. The present invention relates to a crystal, a method for isolating the crystal, and a recording material containing the crystal.

[Conventional technology]

Conventionally, a colorless or light-colored electron-donating compound (color-forming compound) and an organic or inorganic electron-accepting substance (color developer)
There are pressure-sensitive recording, heat-sensitive recording, energized heat-sensitive recording, and the like as methods for recording information transmitted through the use of a color reaction with an external energy such as pressure, heat, or electricity.

In these recording systems, a fluoran compound is widely used as a coloring compound.

Formula (I) Is a compound described as a color-forming compound in JP-A-60-47068, and the melting point described in the publication is 101 to 103 ° C.

This is used as a coloring material for a recording material, for example, a thermosensitive recording material, and when mixed with a color developer, for example, bisphenol A, it is colored black-gray itself, and when it is applied to paper, it is colored black-gray. (Smeared paper) was obtained, and storage stability (moisture and heat resistance) was poor.

[Problems to be solved by the invention]

An object of the present invention is to improve the disadvantage of a fluoran compound represented by the above formula (I) as a coloring material for a recording material, and to provide a formula (I) having excellent properties for a pressure- and heat-sensitive recording material, particularly as a heat-sensitive recording material. An object of the present invention is to provide a fluoran compound represented by I).

[Means for solving the problem]

The present inventors have intensively studied the properties of a recording material using the compound of the formula (I), in particular, a heat-sensitive recording material in order to improve the above-mentioned disadvantages. The presence of stable crystals that exhibit a higher melting point than
The present inventors have found that this crystal has excellent performance as a color-forming material for pressure- and heat-sensitive recording, and have found a method of isolating this crystal, thereby completing the present invention.

That is, the present invention provides a compound of the formula (I) Which is a crystal of a fluoran compound represented by the following formula: which has a diffraction angle (2θ) of 16.7 °, 2
Strong peaks at 0.5 ゜ and 21.9 ゜, 15.7 ゜, 19.4 ゜, 20.
It is characterized by an X-ray diffraction pattern showing relatively strong peaks at 2 ° and 22.5 °, and is a crystal of a fluoran compound having a melting point of 162 to 164 ° C.

In addition, this is a method of isolating the crystals of the fluoran compound.

 Further, it is a recording material containing these crystals.

The fluoran compound of the formula (I) comprises a benzoic acid derivative of the formula (II) and a diphenylamine derivative of the general formula (III): (In the formula, R represents a lower alkyl group.) For example, concentrated sulfuric acid, concentrated sulfuric acid to which fuming sulfuric acid is added, polyphosphoric acid, phosphorus pentoxide, anhydrous aluminum chloride and the like, particularly preferably concentrated sulfuric acid It is produced by making it alkaline after the reaction in it.

The dehydration condensation reaction is usually performed at a reaction temperature of 0 to 100 ° C for several hours to 100 hours.

The reaction temperature may be from 0 to 0, particularly when the reaction is carried out in concentrated sulfuric acid.
A temperature of 50 ° C. is particularly preferred. Since the reaction time depends on the reaction temperature, the reaction is carried out for a sufficient time. After the dehydration condensation, the alkali treatment usually carried out is to adjust the pH to 9 to 12 with potassium hydroxide, sodium hydroxide aqueous solution, etc.
It is preferable to carry out in a temperature range of 100 ° C. At this time, the alkali treatment may be performed in the presence of an organic solvent other than water, such as benzene or toluene.

Crystals of the fluoran compound of the present invention, the product obtained by the above reaction is benzene, toluene, aromatic hydrocarbon solvents such as xylene, methanol, ethanol, isopropanol, alcohol solvents such as n-butanol, or acetonitrile, It can be precipitated as a crystal from a polar solvent such as dimethylformamide or a mixture thereof, and then isolated as a stable crystal.

In particular, among the above solvents, an alcohol solvent or a polar solvent is preferably 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 still more preferably 10% by weight or less.

If the water content exceeds 50% by weight, it becomes difficult to isolate stable crystals.

As a method for precipitating crystals, a method is often used in which a fluoran compound is once completely dissolved in a solvent and then precipitated by cooling. At this time, if necessary, the fluoran compound may be completely dissolved by heating at room temperature or higher in the range of the boiling point of the solvent. After complete dissolution, crystals are precipitated with stirring or standing.

Isolation of the precipitated crystals can be suitably performed by a known method, for example, a filtration method, without any special method.

After the isolation, if necessary, an operation of washing or re-dissolving with an organic solvent having a water content of 50% by weight or less (for example, the above-mentioned organic solvent) and then precipitating as crystals may be performed.

After isolation, it is dried by a usual method to obtain a crystalline fluoran compound.

The crystals of the fluoran compound represented by the formula (I) of the present invention isolated by the above method have a melting point of 162 to 164 ° C,
The melting point of the fluoran compound disclosed in JP-A-60-47068 is higher by 60 ° C. or more than the melting point of 101 to 103 ° C.

Further, as shown in FIG. 1, the powder X-ray diffraction pattern shows strong peaks at diffraction angles (2θ) of 16.7 °, 20.5 ° and 21.9 °, and relatively strong peaks at 15.7 °, 19.4 °, 20.2 ° and 22.5 °. The peaks are shown (± 0.
An error of about 2 mm is acceptable).

The compound of formula (I) isolated by the isolation method disclosed in JP-A-60-47068 is a powder X-ray diffraction pattern as shown in FIG. It indicates that it is amorphous (amorphous).

That is, the crystals of the fluoran compound of the present invention are disclosed in
This is significantly different from that disclosed in Japanese Patent Application Laid-Open No. 60-47068.

The crystals of the fluoran compound represented by the formula (I) of the present invention isolated as described above can be used as a coloring compound in various recording materials. In this case, it may be used alone or, for example, in order to adjust the color hue or the like, other color-forming compounds such as triphenyllactones, fluorans, and spiropyrans may be used as desired. Can be mixed and used.

That is, when the fluoran compound crystal represented by the formula (I) is used, for example, as a pressure-sensitive recording material, it is used in a solvent commonly used in this field, for example, an alkylbenzene (such as n-dodecylbenzene), Alkyl biphenyl (triethyl biphenyl, diisopropyl diphenyl, etc.), hydrogenated terphenyl, alkyl naphthalene (diisopropyl naphthalene, etc.), diaryl ethane (phenyl xylyl ethane, styrenated ethyl benzene, etc.), or various chlorinated paraffin solvents Dissolved in a single or mixed solvent of the following, coacervation method, interfacial polymerization method and the like, gelatin, melamine-aldehyde or urea-aldehyde resin, polyurethane,
A microcapsule having a partition wall made of polyurea, polyamide, or the like is encapsulated in a microcapsule, and the aqueous dispersion of the obtained capsule is mixed with a suitable binder (eg, starch paste, latex, etc.) and a suitable support (eg, paper, (A plastic sheet, resin-coated paper, etc.), and used as a pressure-sensitive recording sheet.

Of course, the above-mentioned capsule dispersion liquid is applied to one surface of the support, and a developer coating solution mainly containing a color developer is applied to the opposite surface. By applying a coating solution in which a capsule and a developer are mixed, or by applying a developer coating solution after applying a capsule dispersion, the capsule and the developer coexist on the same surface, so-called It can also be used for single copy sheets.

In this case, as the color developer, a very large number of copolymers of salicylic acid, phenols and aldehydes (for example, formaldehyde resin), and substituted salicylic acids (alkyl-substituted, aryl-substituted or aralkyl-substituted) are known,
For example, there is 3,5-di-α-methylbenzyl salicylic acid), a co-condensation resin of substituted salicylic acid and styrene, an alkylphenol (for example, octylphenol), and a phenol-aldehyde resin (for example, a novolak resin of p-phenylphenol). Or a metal salt thereof (for example, zinc, magnesium, aluminum, calcium,
Metal salts such as tin and nickel), and activated clay.

When used for a heat-sensitive recording material, crystals of the fluoran compound represented by the formula (I) and a developer (for example, bisphenol A or a halide or alkylated product thereof, dihydroxydiphenyl sulfone or a halide or alkylated product thereof, hydroxybenzoic acid) Acid esters, phenols such as hydroquinone monoethers, salicylic acid derivatives, salicylic acid amide derivatives,
A binder (for example, an organic developer such as a urea derivative or a thiourea derivative, or an inorganic developer such as acid clay, apadalite, activated clay, aluminum chloride, or zinc bromide) Polyvinyl alcohol or a modified product thereof, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, gum arabic, a salt of a styrene-maleic anhydride copolymer or a copolymer of isobutylene-acrylic acid-maleic anhydride, etc.), pigments (talc, kaolin , Calcium carbonate, etc.) and, if necessary, a sensitizer (ester of higher fatty acid amide, aromatic carboxylic acid, or sulfonic acid, aromatic or aromatic group-substituted aliphatic ether, or aromatic or aromatic) Sensitizers for generally known thermosensitive recording materials such as aliphatic hydrocarbons substituted with an aromatic group), and other additives. Agents (e.g., ultraviolet absorbers, antifoaming agents, etc.) was added and a fine dispersion, a suitable support (e.g.,
Paper, plastic sheet, resin-coated paper, etc.) and used as a heat-sensitive recording material. Of course, it can be used without problem 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).

[Action]

When the crystals of the fluoran compound of the present invention are used in a pressure-sensitive recording material, the solubility in capsule oil, which is an important property strongly desired for a color-forming compound for a pressure-sensitive recording material, is high, and the color is formed after the color is formed. The weather resistance of the 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.

The solubility indicated the presence or absence of crystal precipitation after 5% by weight of each compound in each oil was once heated and dissolved and stored at 5 ° C for one week.

In the table, ○ indicates no crystal precipitation, and × indicates the presence of crystal precipitation.

Incidentally, SAS-296 is a capsule oil manufactured by Nippon Petrochemical, and KMC-113 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 when producing a pressure-sensitive recording material, there is no crystal precipitation during storage in capsule oil, and further, there is no danger of crystal precipitation in microcapsules after microencapsulation. This is a great feature of the crystal.

Further, when the crystal of the present invention is used for a heat-sensitive recording material, it has a melting point of 1 produced by the method described in JP-A-60-47068.
For example, whiteness (whiteness) of paper immediately after application of thermal paper using bisphenol A as a color developer or storage stability of the paper as compared with the case of using a compound of formula (I) showing 01 to 103 ° C. (Moisture heat resistance, etc.) are very excellent. The results are summarized in Table 2.

The determination of the results was made by visual observation. ○ indicates a thermal paper with high whiteness, X indicates a thermal paper colored in black gray, and XX indicates a thermal paper almost colored in black. The evaluation after the moist heat test was carried out by examining paper stains after storage at 60 ° C. and 90% relative humidity for 24 hours.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

Example 1 110 g of 2- (4'-N-isopropyl-N-2 "-methoxyethylamino-2'-hydroxybenzoyl) benzoic acid (compound of formula (II)) is added to 550 g of 96% sulfuric acid at 10 to 15 ° C.
After dissolution in 4-methoxy-2-methyldiphenylamine (compound of the general formula (III) wherein R is a methyl group) 6
7 g was added at the same temperature, and the mixture was stirred at 10 to 15 ° C. for 24 hours. The reaction mixture was discharged into 3000 ml of ice water, the precipitated solid was collected, washed with water, added to a 10% aqueous NaOH solution (1000 ml), further added with 1000 ml of toluene, and then stirred at 60 to 70 ° C. for 2 hours. . After the toluene layer was separated and washed with warm water until neutral, the toluene layer was separated, the toluene was concentrated under reduced pressure at 40 ° C, methanol (300 ml) was added to the residue, and the precipitate was filtered. After further washing at 60 ° C., drying was carried out at 60 ° C. for 24 hours to obtain 127 g of a fluoran compound represented by the formula (I) as colorless crystals.

Melting point: 162-164 ° C. A toluene solution of this compound is colorless and transparent, and quickly develops a reddish black color on silica gel.

In a 95% acetic acid aqueous solution, the absorption maximum was observed at 455 nm and 594 mn.

 The powder X-ray diffraction pattern is shown in FIG.

Reference Example 1 (Production of compound of formula (I) by the method described in JP-A-60-47068) 2- (4'-N-isopropylamino-N-2 "-methoxyethylamino-2'-hydroxybenzoyl ) After dissolving 17.9g of benzoic acid in 150g of 96% sulfuric acid at 10 ~ 15 ° C,
10.7 g of -methoxy-2-methyldiphenylamine was added at the same temperature, and the mixture was stirred at 10 to 15 ° C for 24 hours. After the reaction mixture was poured into 800 g of ice water, the precipitate was separated by filtration, washed with water, and then 800 ml of water.
Then, 200 ml of 10% aqueous NaOH was added, and the mixture was stirred at 60 to 70 ° C. for 2 hours. The solid was filtered, washed with water and dried.
24 g of the obtained dried product is 30 g of ethylene glycol, and further,
The solid precipitated from 500 g with 60% aqueous methanol was collected and 30
Drying at 0 ° C. yielded 13.5 g of a white solid.

 Melting point: 101-103 ° C. The powder X-ray diffraction pattern is shown in FIG.

Example 2 (Preparation of thermal recording paper using the crystal of the present invention) A mixture of 10 g of the crystal obtained in Example 1, 5 g of a 10% aqueous solution of polyvinyl alcohol, and 37.5 g of water was pulverized to a sand mill particle size of 3 µm.

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, 60% light calcium carbonate aqueous dispersion salt 18.
3 g, 88 g of 10% polyvinyl alcohol aqueous solution and water 51.
9 g were mixed.

This mixture was applied to 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. The heat-sensitive recording paper developed a very reddish black color very quickly upon heating.

Further, even when this heat-sensitive recording paper was stored at 60 ° C. and 90% relative humidity for 24 hours, there was no staining at all (Table 2).

Reference Example 2 (Preparation of a thermal paper using the fluoran compound represented by the formula (I) having a melting point of 101 to 103 ° C. produced in Reference Example 1) In Example 2, instead of the crystals isolated in Example 1, When a thermosensitive recording paper was prepared according to the method described in Example 2 except that the compound prepared in Reference Example 1 was used, the paper immediately after coating was already stained black-gray. Also add this paper to 60
When stored at 90 ° C. and 90% relative humidity for 24 hours, the color almost changed to black (Table 2).

Example 3 (Preparation of pressure-sensitive recording paper using the crystal of the present invention) Preparation of upper (CB) paper and lower (CF) paper was produced as follows.

That is, 10% of the ethylene-maleic anhydride copolymer
An aqueous solution (100 g) and water (240 g) were mixed, the pH was adjusted to 4.0 with a 10% aqueous sodium hydroxide solution, and 5% by weight of the crystals obtained in Example 1 was dissolved in phenylxylylethane (Nippon Petrochemical Co., Ltd.).
SAS-296) After mixing 200 g and emulsifying with a homomixer,
A methylol melamine aqueous solution having a solid content of 50% (Euramine T-30 manufactured by Mitsui Toatsu Chemicals, Inc.) (60 g) was added, and the mixture was stored at 55 ° C. for 3 hours with stirring to obtain a microcapsule dispersion having an average particle size of 5.0 μm.

In 100 g of this microcapsule dispersion, wheat flour starch granules 4.
0 g and 20 g of oxidized starch paste 20 g and water 116 g are added and dispersed,
It was applied to a paper having a basis weight of 40 g / m ^{2 so} that the coating amount was 5 g / m ² in terms of solid content, 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 color developing agent, is pulverized in a sand grinding mill in water in the presence of a small amount of a polymer anionic surfactant, and has a solid content of 40%. A weight% aqueous dispersion was obtained. Using this aqueous dispersion, an aqueous paint of the following composition (solid content 30%)
Was applied to a high-quality paper having a basis weight of 40 g / m ^{2 so} as to have a dry coating amount of 5.5 g / m ² , thereby producing CF paper.

Composition of water-based paint Solid weight (g) Light calcium carbonate 100 Developer 20 Adhesive Oxidized starch 8 Synthetic latex 8 Weight so that the microcapsule application surface of CB paper and the developer application surface of CF paper face each other. When combined, written, and pressed, a red-black color image was obtained on the developer-coated surface. Light fastness of the color images, moisture resistance and NO _X resistance practically no problem.

〔effect〕

The crystalline fluoran compound of the formula (I) of the present invention has a higher melting point and very good crystallinity than the conventionally known fluoran compound of the formula (I), and is excellent as a recording material. Has performance.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction diagram of the crystalline fluoran compound represented by the formula (I) of the present invention. FIG. 2 is an X-ray diffraction diagram of a fluoran compound represented by the formula (I) having a melting point of 101 to 103 ° C. produced and isolated in Reference Example 1. In each drawing, the horizontal axis represents the diffraction angle (2θ), and the vertical axis represents the diffraction intensity.

Continuation of front page (56) References JP-A-60-47068 (JP, A) JP-A-60-202155 (JP, A) JP-A-60-217267 (JP, A) JP-A-62-167086 (JP) (A) JP-A-1-299081 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07D 493/10 C09B 11/28 B41M 5/16, 5/18 CA (STN) REGISTRY (STN)

Claims (4)

(57) [Claims] (1) Formula (I) In the X-ray diffraction method using Cu-Kα ray,
(2θ) Strong peak at 16.7 ゜, 20.5 ゜ and 21.9 ゜, 1
Crystals of fluoran compounds characterized by X-ray diffraction patterns showing relatively strong peaks at 5.7 °, 19.4 °, 20.2 ° and 22.5 °. 2. The fluoran compound crystal according to claim 1, which has a melting point of 162 to 164 ° C. 3. The method according to claim 1, wherein the fluoran compound represented by the formula (I) is precipitated as crystals from an organic solvent having a water content of 50% by weight or less and then isolated. The method for isolating a crystal of a fluoran compound according to item (1) or (2). 4. A recording material containing a crystal of the fluoran compound according to claim 1 or 2.