JPH04117384A - Crystal of fluoran compound, isolation of the crystal and recording material containing the crystal - Google Patents

Abstract

NEW MATERIAL:The crystal of a compound of formula I. By X-ray diffraction (Cu-Kalpha) the crystal exhibits strong peaks at 2theta=16,7 deg., 20.5 deg., and 21.9 deg. and relatively strong peaks at 15.7 deg., 19.4 deg., 20.2 deg., and 22.5 deg.; melting point: 162-164 deg.C. USE:A pressure-sensitive and heat-sensitive recording material. PREPARATION:A benzoic acid derivative of formula II is subjected to a dehydrative condensation reaction with a diphenyl amine derivative of formula III (R is lower alkyl) in the presence of a dehydration-condensing agent such as concentrated sulfuric acid or phosphorus pentaoxide at 0-50 deg.C for several hours to 100 hours, and the reaction product is treated with an alkali at pH of 9-12.

Description

Detailed Description of the Invention [Field of Industrial Application] 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. The present invention relates to a crystal, a method for isolating the crystal, and a recording material containing the crystal.

[Conventional technology]

Conventionally, color reaction between a colorless or light-colored electron-donating compound (color-forming compound) and an organic or inorganic electron-accepting substance (Ij1 coloring agent) is used, and the coloring reaction is mediated by external energy such as pressure, heat, or electricity. There are pressure-sensitive recordings, heat-sensitive recordings, electric current heat-sensitive recordings, etc. as methods for recording transmitted information.

In these recording methods, fluoran compounds are widely used as color-forming compounds.

The fluoran compound represented by formula (I) is disclosed in JP-A-60-4706
This compound is described as a color-forming compound in Publication No. 8, but the melting point described in the publication is 101 to 103.
It is ℃.

This product is used as a color-forming material for recording materials, such as heat-sensitive recording materials, and is used as an ointment agent, such as bisphenol A.
When mixed with, it colors itself black-gray, and when it is applied to paper, only paper colored black-gray (background stain) is obtained.
Furthermore, it has the disadvantage of poor storage stability (moisture and heat resistance).
It lacked practicality.

[Invention or problem to be solved]

The object of the present invention is to improve the lack of a fluoran compound represented by the above formula (I) as a coloring material for recording materials, and to have excellent properties for pressure-sensitive and heat-sensitive recording materials, especially as a heat-sensitive recording material. An object of the present invention is to provide a fluoran compound represented by formula (1).

[Means to solve the problem]

In order to improve the above-mentioned drawbacks, the present inventors have made extensive studies on the properties of recording materials, especially heat-sensitive recording materials, using the compound of formula (■). We have found that there is a stable crystal that has a melting point higher than that of the crystal, that this crystal has excellent performance as a coloring material for pressure-sensitive and heat-sensitive recording, and that we have found a method for isolating this crystal. completed.

That is, the present invention involves crystallization of a fluoran compound represented by formula (I), in which Cu- has α
In the X-ray diffraction method using rays, the diffraction angle (2θ) is 16.7
Strong peaks at 20.5° and 21.9°, 15.
It is characterized by an X-ray diffraction diagram showing relatively strong peaks at 7°, 19.4°, 20.2° and 22.5°, and is a crystal of a fluoran compound with a melting point of 162-164°C. be.

It is also a method for isolating crystals of this fluoran compound.

Furthermore, it is a recording material containing these crystals.

The fluoran compound of formula (1) is prepared by combining a benzoic acid derivative of formula (II) and a diphenylamine derivative of general formula (I[I), (in the formula, R represents a lower alkyl group), for example, concentrated sulfuric acid or fuming sulfuric acid. It is produced by reacting in concentrated sulfuric acid, particularly preferably in the presence of a dehydration condensing agent such as concentrated sulfuric acid, polyphosphoric acid, phosphorus pentoxide, or anhydrous aluminum chloride, and then making it alkaline.

The dehydration condensation reaction is usually carried out at a reaction temperature of 0 to +00°C for several hours to 100 hours.

The reaction temperature is between 0 and 5, especially when the reaction is carried out in concentrated sulfuric acid.
Particularly preferred is a temperature of 0°C. Since the reaction time depends on the reaction temperature, a sufficient amount of time is required for the reaction. Further, after the dehydration condensation, the alkaline treatment that is usually carried out is preferably carried out at a temperature range of 0 to 100° C. with the pH adjusted to 9 to 12 using potassium hydroxide, sodium hydroxide, or the like. At this time, the alkali treatment may be performed in the presence of an organic solvent other than water such as benzene or toluene.

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

Furthermore, among the above-mentioned solvents, alcoholic solvents or polar solvents are particularly 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, still more preferably 10% by weight or less.

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

The method often used to precipitate crystals is to completely dissolve the fluoran compound in a solvent and then cool and precipitate it.

At this time, if necessary, the fluoran compound may be completely dissolved by heating at a temperature above room temperature or above the boiling point of the solvent. After complete dissolution, crystals are precipitated by stirring or standing still.

Isolation of the precipitated crystals can be suitably carried out by any known method, such as filtration, without any special method.

After isolation, if necessary, it may be further washed or redissolved with an organic solvent having a water content of 50% by weight or less (for example, the above-mentioned organic solvent), and then precipitated as crystals.

After isolation, a crystalline fluoran compound can be obtained by drying by a conventional method.

The crystals of the fluoran compound represented by the formula (1) of the present invention isolated by the above method have a melting point of 162 to 164°C, and the melting point of the fluoran compound disclosed in JP-A-60-47068 is Although it is 101-103°C, it is more than 60°C higher than the average temperature.

As shown in Figure 1, the powder X-ray diffraction diagram shows strong peaks at diffraction angles (2θ) of 16.7°, 20.5° and 21.9°, and strong peaks at diffraction angles (2θ) of 15.7° and 19.4°. , 20.2° and 22.5° (note that an error of about ±0.2° is allowed in the display of diffraction angles).

The compound of formula (I) isolated by the isolation method disclosed in JP-A-60-47068 was prepared as a powder X as shown in FIG.
This is a line diffraction diagram, showing that the crystallinity is low and that it is substantially amorphous.

That is, the crystals of the fluoran compound of the present invention are disclosed in Japanese Unexamined Patent Publication No. 6
This is significantly different from that disclosed in Japanese Patent No. 0-47068.

The crystals of the fluoran compound represented by formula (I) of the present invention isolated as described above can be used as a color-forming compound in various recording materials. In this case, it may be used alone, or furthermore, other color-forming compounds such as triphenyl lactones, fluorans, spiropyrans, etc. may be used as desired to adjust the hue of the color. Depending on the situation, they may be mixed and used.

That is, when the crystal of the fluoran compound represented by formula (I) is used, for example, as a pressure-sensitive recording material, it is mixed with a solvent commonly used in this field, such as an alkylhenyne-based (n-dodenlebenzene). ), alkylhyphenyls (triethylhyphenyl, diisopropyldiphenyl, etc.), hydrogenated terphenyls, alkylnaphthalenes (diisopropylnaphthalene, etc.), diarylethanes (phenylxylylethane, styrenated ethylbenzene, etc.)
, or dissolved in a single or mixed solvent of various chlorinated paraffinic solvents, and the resulting solution is processed by a method such as a coacervation method or an interfacial polymerization method to produce ceratin, melamine-aldehyde, or urea-aldehyde resin, polyurethane, or polyurea. The aqueous dispersion of the resulting capsules is encapsulated in microcapsules having partition walls made of polyamide, etc., and mixed with a suitable binder (
For example, it can be coated on a suitable support (for example, paper, plastic sort, resin-coated paper, etc.) together with starch paste, latex, etc. to form a pressure-sensitive recording sheet and used.

Of course, it is possible to apply the so-called Cow Sheet H, in which one side of the support is coated with the above capsule dispersion liquid and the other side is coated with a color developer coating liquid mainly consisting of a color developer. A coating liquid that contains the capsules and color developer mixed together is applied, but instead of applying the developer coating liquid on top of the capsule dispersion, the capsules and color developer are coexisted on the same surface. It can also be used as a stand-alone copy sheet.

In this case, the color developer may be a copolymer of salicylic acid, a phenol, and an aldehyde (e.g., narumaldehyde resin), a substituted salicylic acid (alkyl-substituted, aryl-substituted or aralkyl-substituted product), etc. 3.5-) ~ α-methylpencil salicylic acid), cocondensation resins of substituted salicylic acid and styrene, alkylphenols (e.g., octylphenol), phenol-aldehyde resins (e.g., nophorac resin of p-phenylphenol), or These metal salts (for example, metal salts of zinc, magnesium, aluminum, calcium, tin, nickel, etc.) and activated clays may also be mentioned.

Furthermore, when used in a heat-sensitive recording material, crystals of the fluoran compound represented by formula (I) and a color developer (for example, bisphenol A or its halide or alkylated product,
dihydroxydiphenylsulfone or its halokenized or alkylated products, hydroxybenzoic acid esters, phenols such as hydroquinone monoethers, organic color developers such as salicylic acid derivatives, salicylic acid amide derivatives, urea derivatives, thiourea derivatives, etc. Alternatively, a fine aqueous dispersion of acid clay, Avadal guide, activated clay, inorganic color developer such as aluminum chloride, zinc bromide) and a binder (for example, polyhinyl alcohol or its modified products, methyl cellulose, hydroxyethyl cellulose,
Calhokit methyl cellulose, arabicum, styrene-maleic anhydride copolymer salt or isobutylene
acrylic acid-maleic anhydride copolymer, etc.), pigments (talc, kaolin, calcium carbonate, etc.), and if necessary, sensitizers (higher fatty acid amides, aromatic carboxylic acids,
or generally known sensitizers for heat-sensitive recording materials such as sulfonic acid esters, aromatic or aromatic group-substituted aliphatic ethers, or aromatic or aromatic group-substituted aliphatic hydrocarbons)
, other additives (e.g. ultraviolet absorbers, antifoaming agents, etc.)
is added to make a fine dispersion, and a suitable support (e.g. paper,
It can be coated onto plastic sheets, resin-coated paper, etc.) and used as a heat-sensitive recording material. Of course, it can also be used in a system using a solvent instead of an aqueous dispersion system without any problem. Furthermore, it can also be used in applications that use other color-forming compounds (for example, temperature-indicating materials).

[Effect]

When the crystal of the fluoran compound of the present invention is used in a pressure-sensitive recording material, it has high solubility in capsule oil and color development after color development, which are important properties that are strongly desired for color-forming compounds for pressure-sensitive recording materials. The weather resistance of the statue is excellent.

That is, the results of comparing the solubility of the crystal of the present invention in commercially available capsule oil with the fluoran compounds of formulas (A), (B) and (C) are shown in Table 1.

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

(Special Publication No. 48-43296) 61-264058) 60-47068) Table 1 In the table, ◯ indicates no crystal precipitation, and × indicates crystal precipitation.

In addition, 5AS-296 is manufactured by Nippon Petrochemical, KMC-113
is a capsule oil made by a prefectural chemical company.

As is clear from Table 1, the crystal of the present invention has the formula (A),
The solubility in each oil is higher than that of the fluoran compounds of formulas (B) and (C).

This means that when the pressure-sensitive recording material is produced, there will be no crystal precipitation during storage in capsule oil, and there is no fear of crystal precipitation in the microcapsules after microencapsulation. This is a major feature of crystals.

Further, when the crystal of the present invention is used in a heat-sensitive recording material, when a compound of formula (I) having a melting point of 101 to 103°C produced by the method described in JP-A-60-47068 is used, For example, thermal paper using bisphenol A as a color developer has excellent paper whiteness (whiteness) immediately after coating or storage stability (moisture heat resistance, etc.). The results are summarized in Table 2.

Judgment of the results in Table 2 was made visually. ○ represents thermal paper with high whiteness, × represents thermal paper colored black and gray, and XX represents thermal paper colored almost pitch black. The evaluation after the heat and humidity test was to check the stains on the paper after storage for 24 hours at 60° C. and 90% relative humidity.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples.

Example 1 2-(4′-N-isopropyl-N-2”-methquinethylamino-2-hytroquinhenzoyl)benzoic acid (compound mug of formula (■) was dissolved in 550 g of 96% sulfuric acid for 10 to
After dissolving at 15°C, 67 g of 4-methoxy-2-methyldiphenylamine (a compound in which R is a methyl group in the linear formula (III)) 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 30001+J of ice water, the precipitated solid was collected, and after washing with water, the solid was diluted with 10% N
Add to aOH water (1000 I) and add toluene 100
After adding 0-, the mixture was stirred at 60 to 70°C for 2 hours. After separating the toluene layer, wash it with warm water until it becomes neutral, separate the toluene layer, concentrate the toluene at 40°C under reduced pressure, add methanol (300-) to the residue, and filter the precipitated crystals. After further washing with methanol, drying was performed at 60° C. for 24 hours to obtain 127 g of a fluoran compound represented by formula (I) as colorless crystals.

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

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

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

Reference Example 1 (Formula according to the method described in JP-A No. 60-47068 (
(2) Preparation of the compound of (2)) 17.9 g of 2-(4'-N-isopropylamino-N-2-methoxyethylamino-2-hydroquinohenzoyl)benzoic acid was dissolved in 150 g of 96% sulfuric acid for 1'0 to 15%. After dissolving at °C, 4-methoxy-2-methyldiphenylamine 1
0.7 g was added at the same temperature and stirred at 10-15°C for 24 hours. After pouring the reaction mixture into 800 g of ice water, the precipitate was separated by filtration and washed with water. Put it inside and add 10%N
200 ml of aOH water was added, and the mixture was stirred at 60 to 70°C for 2 hours. The solid was filtered, further washed with water, and then dried. The obtained 24 g of dried product was mixed with 30 g of ethylene glycol and the solid precipitated from 500 g of 60% aqueous methanol was collected and dried at 30° C. to obtain 13.5 g of white solid.

Melting point 101~+03℃ The powder X-ray diffraction pattern is shown in FIG.

Example 2 (Preparation of thermal recording paper using crystals of the present invention) A mixture of 10 g of the crystals obtained in Example 1, 5 g of a 10% aqueous solution of borihinyl alcohol, and 37.5 g of water was made into fine particles with a Santomil particle size of 3 μm. It became.

On the other hand, hisphenol A was similarly dispersed to obtain a color developer dispersion of 3896. 65.8 g of this color developer dispersion, 50 g of the aqueous dispersion of the above crystals, 18.3 g of a 60% light carnoum carbonate aqueous dispersion, 88 g of a 10% aqueous polyhinyl alcohol solution, and 51.9 g of water were mixed.

This mixed solution was applied to white base paper using Wire Lot Nα1o, and then air-dried at room temperature to obtain a very white thermosensitive recording paper with no background stains. When heated, this thermosensitive recording paper very quickly developed a slightly reddish black color.

In addition, this thermal recording paper was heated at 60°C, 190% relative humidity for 2 hours.
Even after storage for 4 hours, there was no staining at all (Table 2).

Reference Example 2 (Formula showing a melting point of 101 to 103°C manufactured in Reference Example 1 (
Preparation of thermal paper using a fluoran compound represented by I) In Example 2, the same procedure as described in Example 2 was used except that the compound produced in Reference Example 1 was used instead of the crystal isolated in Example 1. When heat-sensitive recording paper was prepared according to the method described above, the paper was already stained black and gray immediately after coating. Also, heat this paper at 60℃.
, 909'6 When stored for 24 hours in a relative humidity, the color had turned completely black (Table 2).

Example 3 (Preparation of pressure-sensitive recording paper using the crystal of the present invention)
) paper and bottom (CF) paper were produced as follows.

That is, lO% of ethylene-maleic anhydride copolymer
100 g of aqueous solution and 240 g of water were mixed, the p) was adjusted to 14.0 with 10% aqueous sodium hydroxide solution, and 5% by weight of the crystals obtained in Example 1 were dissolved in phenylquinrylethane (5AS-296 manufactured by Nippon Petrochemical). After mixing 200 g and emulsifying with a homomixer, a methylolmelamine aqueous solution with a solid content of 50% (Neelamine T-3 manufactured by Mitsui Toatsu Chemical Co., Ltd.
0) was added and stored at 55° C. for 3 hours while stirring to obtain a microcapsule dispersion having an average particle size of 5.0 μm.

To 100 g of this microcapsule dispersion, 4.0 g of wheat flour starch granules, 20% oxidized starch paste QQg, and 116 g of water were added and dispersed, and the coating amount or solid content was 5 g/m2 on paper with a basis weight of 40 g/m2. CB paper was obtained.

On the other hand, CF paper uses a zinc salt of a co-condensed resin of substituted salicylic acid and styrene as a color developer, and is made fine by a Sandgeriding mill in water in the presence of a small amount of polymeric anionic surfactant. A 40% by weight aqueous dispersion was obtained.

Using this aqueous dispersion, a water-based paint with the following composition (solid content: 30
%) and dry coating amount 5 on high-quality paper with a basis weight of 40 g/m2.
．． It was coated to give a weight of 5 g/m2 to prepare CF paper.

Composition of water-based paint Solid weight (g) Light calcium carbonate 100 Color developer 20 Adhesive Oxidized starch 8 Synthetic latex 8 The microcapsule-coated surface of CB paper and the color developer-coated surface of CF paper were placed in a pile so that they faced each other. When they were combined, written, and pressed, a red and black colored image was obtained on the surface coated with the color developer. The light resistance, moisture resistance and NO3 resistance of this colored image had no practical problems.

[Effect] The crystalline fluoran compound of formula (1) of the present invention has a higher melting point and very good crystallinity than the conventionally known fluoran compound of formula (I), and is suitable for recording materials. It has excellent performance as

[Brief explanation of drawings]

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

Claims (5)

[Claims] (1) Formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) A crystal of a fluoran compound represented by (2) In the X-ray diffraction method using Cu-Kα rays, (2θ
) Strong peaks at 16.7°, 20.5° and 21.9°, 15.7°, 19.4°, 20.2° and 22.
The crystal of the fluoran compound represented by formula (I) according to claim (1), characterized by an X-ray diffraction diagram showing a relatively strong peak at 5°. (3) The crystal of the fluoran compound according to claim (1), which has a melting point of 162 to 164°C. (4) A claim characterized in that the fluoran compound represented by formula (I) according to claim (1) is precipitated as crystals from an organic solvent with a water content of 50% by weight or less, and then isolated. A method for isolating a crystal of a fluoran compound according to (2) or (3). (5) A recording material containing crystals of the fluoran compound according to claim (1), (2) or (3).