JPH08229303A - Production of solid fine particle and device therefor - Google Patents

Abstract

PURPOSE: To obtain the solid fine particle for a silver halide photographic sensi tive material enhanced in light absorptivity in the method for dissolving a compd. in solvent and depositing a solid fine particle of the compd. By dissolv ing the compound in solvent under the high temperature/pressurizing conditions to eliminate the contaminant due to the wear of media. CONSTITUTION: A compd. is dissolved in solvent, and a solid fine particle is deposited and produced. In this case, a compd., especially a compd. sparingly soluble in solvent, is dissolved in solvent preferably along with a surfactant at high temp. and under pressure (the solvent is pressurized to a temp. above the atmospheric b.p.). The solid fine particle is deposited by mixing the compd. soln. with another solvent, or the soln. is cooled or the solvent of the soln. is vaporized to deposit the fine particle. The solid fine particle thus obtained has >=10m<2> /g specific surface (BET).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing solid fine particles, and more particularly to a method for producing solid fine particles used in a silver halide photographic light-sensitive material.

[0002]

2. Description of the Related Art Conventionally, as a method for producing solid fine particles, a mechanical pulverization method using a fine disperser such as a ball mill, a vibration mill, a planetary mill, a sand mill or a roller mill using a surfactant is known. -92716,
No. 55-155350, No. 55-155351, No. 63-197943, Japanese Patent Laid-Open No. 3-182743, and World Patent No. WO88 / 04794. Furthermore, the compound is dissolved by adjusting the pH and the solid fine particles are precipitated by changing the pH, the compound is dissolved in a solvent and mixed with a new solvent, or the solution is cooled or the solvent of the solution is evaporated. There is known a chemical condensation method or the like in which solid fine particles are deposited by doing so.

However, each of these conventional techniques has problems. For example, in the mechanical pulverization method performed using various mills, contamination due to abrasion of media is included. Further, the method of dissolving the compound in a solvent to precipitate solid fine particles requires a huge amount of the solvent when the compound is poorly soluble in the solvent, or cannot be carried out when the compound is insoluble.

As a method for dissolving a poorly soluble compound, JP-A-2-15251 and JP-A-2-15251 using a surfactant are used.
No. 252, No. 2-23330, No. 2-23331,
No. 2-23332, No. 2-120848, No. 2-1
Nos. 35438 and 6-79168 are disclosed. Among them, some have proposed a method in which the amount of solvent used is reduced by adding a surfactant.

However, in the case of a compound which is substantially insoluble in a solvent, the fact that the effect of improving the solubility by adding a surfactant cannot be expected cannot be expected. Further, in the method of precipitating solid fine particles by adjusting the pH, the generated salt is liable to agglomerate the particles, and it is difficult to obtain a stable dispersion liquid. Further, in order to remove salt, a new operation such as ultrafiltration or Nudell water washing is required, which is a disadvantage in terms of cost.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for producing solid fine particles which does not have the above-mentioned drawbacks. Specifically, there is no contamination due to abrasion of media and high absorption of light. It is an object of the present invention to provide a production method which has performance and is capable of obtaining fine particle solids.

[0007]

The above objects of the present invention have been solved by the following.

(1) A method for producing solid fine particles, which comprises dissolving the compound in a solvent to precipitate solid fine particles of the compound, wherein the compound is dissolved in the solvent under conditions of high temperature and pressure.

(2) The method for producing solid fine particles according to item (1), wherein the compound is a compound which is hardly soluble in a solvent.

(3) The method for producing solid fine particles according to item (1), wherein the compound is dissolved in a solvent together with a surfactant.

(4) The method for producing solid fine particles according to item (1), wherein the solid fine particles are precipitated by mixing the compound solution and a new solvent.

(5) The method for producing solid fine particles according to item (1), wherein the solid fine particles are deposited by cooling the compound solution.

(6) The solid fine particles are deposited by evaporating the solvent of the compound solution (1)
Item 7. A method for producing solid fine particles according to item.

(7) The specific surface area (BET) of solid fine particles is 1
The method for producing solid fine particles according to item (1), which is 0 m ² / g or more.

The present invention will be described in detail below.

In the present invention, high temperature pressurization means a state in which the solvent is heated to a temperature above the atmospheric pressure boiling point under pressurization. This high-temperature pressurization condition is not uniform depending on the target compound type, amount, apparatus and other conditions, but high temperature means 50 ° C-
Refers to the range of 200 ° C. The pressurizing time may be in the range of 0.5 hours to 2 hours.

In the present invention, the compound which is sparingly soluble in the solvent means that the amount of the compound dissolved in the solvent is 10 at the boiling point of the solvent.
Refers to those in wt% or less. The solvent used for dissolving the compound is not particularly limited, but a low boiling point solvent is preferable from the viewpoint of solvent removal. A surfactant may be added when the compound is dissolved.

In order to dissolve the compound in the solvent under the high temperature and pressure conditions as described above and precipitate the solid fine particles from the solution, it is necessary to prevent the crystal from growing as much as possible.

For that purpose, without precipitating crystals,
A method is conceivable in which the solution is brought to an extremely high degree of supersaturation within a short time, and solid fine particles are precipitated from that state by spontaneous nucleation. Instantaneous maximum supersaturation in this case = [amount of dye dissolved in solvent before crystal precipitation] / [amount of dye dissolved in solvent after crystal precipitation] is 10 or more, preferably 10
It is desirable that the condition is 0 or more, and more preferably 1000 or more.

In the present invention, as a precipitation method for precipitating solid fine particles of a compound, a method of mixing a compound solution and a new solvent to precipitate solid fine particles will be described.

The new solvent is not particularly limited as long as it does not substantially dissolve the compound at the liquid temperature when mixed with the solution. Specific solvents include, for example, hydrocarbon solvents such as n-hexane, benzene and toluene, halogenated hydrocarbon solvents such as chloroform and carbon tetrachloride, alcohol solvents such as methanol, ethanol, propanol and butanol, ethyl ether. An ether solvent such as isopropyl ether, a ketone solvent such as acetone or methyl ethyl ketone, an ester solvent such as methyl acetate or ethyl acetate, or water can be used.

For mixing the solution, either a static mixing device having no moving parts in the mixing part or a dynamic mixing device having moving parts can be used, but with a lower power energy, a large stirring effect, that is, A static mixing device that can achieve a reduction in mixing time is preferred. Specific examples of the mixing device include an ejector and a static mixer.

As a method of precipitating solid fine particles by cooling the compound solution, not only the cooling by the melting vessel jacket for instantaneous cooling, but also a cooling coil is provided in the melting vessel to provide a large cooling area. It is particularly preferable to ensure the efficiency in order to increase the precipitation efficiency.

As a method for evaporating the solvent of the compound solution to deposit solid fine particles, a known method such as spray drying can be applied. At this time, it is preferable to make the diameter of the droplet to be sprayed as small as possible. Further, it is efficient and preferable to spray under reduced pressure or to spray under hot air to rapidly evaporate the solvent.

The method of depositing the solid fine particles in the present invention includes the above-mentioned methods. From the viewpoint of easy control of the particle size of the solid fine particles, a method of mixing a compound solution with a new solvent or a compound is used. The method of cooling the solution is particularly preferable.

It is preferable that the solution to be fed to the mixing device is fed by a high pressure gas. In addition, the liquid feeding device for the new solvent is not particularly limited. In the method of precipitating solid fine particles by mixing the solution with a new solvent, it is advisable to add a new surfactant to the dispersion after crystal precipitation for long-term storage and maintenance of dispersion stability against increase in liquid temperature.

In the present invention, a small amount of a similar structural compound different from the target compound in the substituents is added and dissolved to suppress the crystal growth when the compound precipitates, or to stop in the middle of the solid compound. A method of further reducing the particle size of the fine particles can be used.

The present invention is characterized in that the solid fine particles have a specific surface area (BET) of 10 m ² / g or more. Preferably 20 m ² / g or more, more preferably 30 m ²
/ G or more is preferably used.

The solid fine particles obtained in the present invention are used in a silver halide photographic light-sensitive material. Many compounds are used as additives in silver halide photographic light-sensitive materials. A photographic dye will be described as an example.

The silver halide photographic light-sensitive material is provided with a dye layer which absorbs and cuts light in a specific wavelength range in order to prevent image blurring caused by light scattered after passing through or passing through the emulsion layer. There are quite a few

In the X-ray light-sensitive material, in order to increase the sensitivity, a silver halide emulsion layer is coated on both sides of a film support, and an intensifying screen is sandwiched between the both sides, and light emitted from the intensifying screen is used. Designed to be sensitive to. As a problem of the X-ray sensitive material, not only the light emitted from the intensifying screen sensitizes the adjacent silver halide emulsion layer, but also sensitizes the emulsion layer on the opposite side through the film support. That is. The light that crosses the film support is cross-over light (hereinafter referred to as "cross light") that also diffuses laterally while crossing the film support, which causes deterioration of image sharpness.

It is known to dye the emulsion layer or other layers with dyes or pigments for the purpose of absorbing and reducing such transverse light. However, the dye used has problems such as desensitization due to diffusion and migration to the photosensitive emulsion layer, and staining and staining.

On the other hand, with the recent rapid spread of silver halide light-sensitive materials, there is a strong demand for a thinner coating layer to further improve the developability and the drying property.

With respect to the above-mentioned photographic dyes as well, it is required that a small amount of them can exhibit high performance in the constituent layer of the silver halide photographic light-sensitive material, and there is no contamination with others, and they are fine particles and have excellent absorbance. A solid fine particle dye compound was desired.

The method for producing solid fine particles of a dye used in a silver halide photographic light-sensitive material will be described below. The dye used is not particularly limited, but examples thereof include dye compounds represented by the following general formulas (I) to (VI).

[0036]

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In the formula, A and A ′, which may be the same or different, each represents an acidic nucleus, B represents a basic nucleus, Q represents an aryl group or a heterocyclic group, and Q ′ represents a heterocyclic group. And X and Y, which may be the same or different, each represents an electron-withdrawing group, and L ₁ , L ₂ and L ₃
Each represents a methine group. m represents 0 or 1, and n
Represents 0, 1 or 2, and p represents 0 or 1. However, the dyes represented by the general formulas (I) to (VI) have at least one group selected from a carboxy group, a sulfonamide group and a sulfamoyl group in the molecule.

A of the general formulas (I), (II) and (III)
The acidic nucleus represented by A and A ′ is preferably 5-pyrazolone, barbituric acid, thiobarbituric acid, rhodanine, hydantoin, thiohydantoin, oxazolone, isoxazolone, indandione, pyrazolidinedione, oxazolidinedione, Hydroxypyridone,
Examples include pyrazolopyridone.

The basic nucleus represented by B in the general formulas (III) and (V) is preferably pyridine, quinoline,
Examples include oxazole, benzoxazole, naphthoxazole, thiazole, benzthiazole, naphthothiazole, indolenine, pyrrole and indole.

Examples of the aryl group represented by Q in the general formulas (I) and (IV) include phenyl group, naphthyl group,
Examples thereof include a julolidyl group. In addition, the general formula (I),
Examples of the heterocyclic group represented by Q and Q'of (IV) and (VI) include a pyridyl group, a quinolyl group, an isoquinolyl group, a pyrrolyl group, a pyrazolyl group, an imidazolyl group, an indolyl group, a furyl group and a thienyl group. Is mentioned. The aryl group and the heterocyclic group include those having a substituent, and examples of the substituent include an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, a halogen atom, an alkoxycarbonyl group, an aryloxycarbonyl group, and a carboxy group. Group, cyano group, hydroxy group, mercapto group,
Examples thereof include an amino group, an alkoxy group, an aryloxy group, an acyl group, a carbamoyl group, an acylamino group, a ureido group, a sulfonamide group, and a sulfamoyl group, and these substituents may have two or more kinds in combination. As a preferable substituent, an alkyl group having 1 to 8 carbon atoms (for example, methyl group, ethyl group, t-butyl group, octyl group, 2-hydroxyethyl group, 2-methoxyethyl group, etc.), hydroxy group, cyano group, Halogen atom (eg, fluorine atom, chlorine atom, etc.), C1-C6 alkoxy group (eg, methoxy group, ethoxy group, 2-hydroxyethoxy group, methylenedioxy group, butoxy group, etc.), substituted amino group (eg, dimethyl group) Amino group, diethylamino group, di (n-butyl) amino group, N-ethyl-N-hydroxyethylamino group, N-ethyl-N-methanesulfonamidoethylamino group, morpholino group, piperidino group, pyrrolidino group, etc.), Carboxy group, sulfonamide group (eg, methanesulfonamide group, benzenesulfonamide group, etc.), sulfamoyl group (eg, sulfamoyl group) Group, methylsulfamoyl group,
Phenylsulfamoyl group), and these substituents may be combined.

The electron-withdrawing groups represented by X and Y in the general formulas (IV) and (V) may be the same or different, and the σp value of the substituent constant Hammett (edited by Toshio Fujita, “Chemical Domain”). Special Issue No. 122, Structure-Activity Relationship of Drugs, pp. 96-103 (1
979) It is described in Nankodo and other places. ) Is 0.3 or more, for example, a cyano group, an alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group, butoxycarbonyl group, octyloxycarbonyl group, etc.), an aryloxycarbonyl group (eg, phenoxycarbonyl group, 4-hydroxy group). Phenoxycarbonyl group), carbamoyl group (eg carbamoyl group, methylcarbamoyl group, ethylcarbamoyl group, butylcarbamoyl group, dimethylcarbamoyl group, phenylcarbamoyl group, 4-carboxyphenylcarbamoyl group, etc.), acyl group (eg methylcarbonyl group, ethyl Carbonyl group, butylcarbonyl group, phenylcarbonyl group, 4-ethylsulfonamidophenylcarbonyl group, etc.), alkylsulfonyl group (eg, methylsulfonyl group, ethylsulfonyl group) , Butylsulfonyl group, an octyl sulfonyl group, etc.), an arylsulfonyl group (e.g., phenylsulfonyl group, 4-chlorosulfonyl group, etc.).

The methine groups represented by L ₁ , L ₂ and L ₃ in the general formulas (I) to (V) include those having a substituent, and the substituent has, for example, 1 to 6 carbon atoms. Alkyl group (eg methyl group, ethyl group, hexyl group etc.), aryl group (eg phenyl group, tolyl group, 4-hydroxyphenyl group etc.), aralkyl group (eg benzyl group, phenethyl group etc.), heterocyclic group (eg Pyridyl group, furyl group, thienyl group, etc.), substituted amino group (eg, dimethylamino group, diethylamino group, anilino group, etc.), alkylthio group (eg, methylthio group, etc.) can be mentioned.

In the present invention, among the dyes represented by the general formulas (I) to (VI), a dye having at least one carboxy group in the molecule is preferably used, and more preferably the general formula (I). A dye represented by the formula, and particularly preferably a dye in which Q is a furyl group in the general formula (I).

Next, specific examples of the dye used in the present invention will be given.

[0045]

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[0046]

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[0047]

[Chemical 4]

[0048]

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[0049]

[Chemical 6]

[0050]

[Chemical 7]

[0051]

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[0052]

[Chemical 9]

[0053]

[Chemical 10]

[0054]

[Chemical 11]

[0055]

[Chemical 12]

[0056]

[Chemical 13]

Specific examples of the dyes used in the present invention include, in addition to the above, JP-A Nos. 52-92716 and 55-1.
20030, 55-155350, 55-15
5351, 56-12639, 63-1979.
No. 43, JP-A Nos. 2-18838 and 2-1839, World Patent 88/04794, U.S. Patent 4,861,70.
0, 4,950,586, European Patent 489,97
Those described in No. 3 and the like can also be used. The synthetic method can also be carried out according to the methods described in these patents. A specific synthesis example is shown below.

Synthesis Example 1 (Exemplified Dye I-4) 1- (4-carboxyphenyl) -3-cyano-5-pyrazolone 11.5
7.5 g of g, 4-dimethylaminobenzaldehyde and 6.0 g of pyridine were placed in a mixed solvent of 200 ml of methanol and 20 ml of dimethylformaldehyde and reacted at room temperature for 3 days.
The precipitate was collected by filtration and washed well with methanol. The crude crystals were dissolved in 240 ml of methanol, 100 ml of distilled water and 7.0 g of triethylamine, and then 20.0 g of acetic acid was added to cause precipitation. The precipitate was collected by filtration, washed thoroughly with methanol, and dried to obtain 9.2 g of dye (I-4). NMR, I
Confirmed by R and MASS spectra.

Synthesis Example 2 (Exemplary Dye I-15) 1- (4-Carboxyphenyl) -3-cyano-5-pyrazolone 45.8
27.8 g of g, 5-dimethylaminofurfural and 23.7 g of pyridine were placed in a mixed solvent of 800 ml of methanol and 80 ml of dimethylformaldehyde and reacted at room temperature for 4 days. The precipitate was collected by filtration and washed well with methanol. The crude crystals were dissolved in 1000 ml of methanol, 250 ml of distilled water and 16.0 g of triethylamine, and then 40.0 g of acetic acid dissolved in 100 ml of methanol was added for precipitation. The precipitate was collected by filtration, washed thoroughly with methanol and dried to give 42.0 g of dye (I-15).
I got The structure of the compound was confirmed by NMR, IR and MASS spectra.

The solvent used for dissolving the dyes represented by the general formulas (I) to (VI) is not particularly limited, but examples thereof include hydrocarbon solvents such as n-hexane, benzene and toluene, Chloroform, halogenated hydrocarbon solvents such as carbon tetrachloride, alcohol solvents such as methanol, ethanol, propanol and butanol, ether solvents such as ethyl ether and isopropyl ether, ketone solvents such as acetone and methyl ethyl ketone, methyl acetate, An ester solvent such as ethyl acetate is preferable. Among these, use of a low boiling point solvent is desirable from the viewpoint of solvent removal. However, the present invention is not limited to these low boiling point solvents.

In the present invention, a surfactant can be used in dissolving the dye. The surfactant used in the present invention is not particularly limited, and conventionally known nonionic, anionic, cationic or betaine type surfactants can be used alone or in combination. .

Specific examples of the surfactant preferably used in the present invention will be given below, but the present invention is not limited thereto.

[0063]

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[0064]

[Chemical 15]

[0065]

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[0066]

[Chemical 17]

[0067]

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[0068]

[Chemical 19]

The above-mentioned surfactants are known compounds and can be synthesized by referring to the method described in, for example, "Synthesis of surfactants and their applications" by Ryohei Oda et al. (Maki Shoten).

The amount of the above-mentioned surfactant to be used varies depending on the kind of the surfactant, the kind and amount of the target fine particle compound, etc., but usually, the surfactant is 0.
It may be 1 to 20000 mg, preferably 0.5 to 1000 mg, and particularly preferably 1 to 500 mg. The compound is used in a concentration of 0.01 to 10% by weight in a dispersion liquid, preferably 0.1 to 5% by weight.

The crystal precipitation method is not particularly limited, but a method of mixing the dye solution with a new solvent, rapidly cooling the dye solution, or evaporating the solvent of the dye solution is preferable. The conditions for depositing the dye are as follows: the instantaneous maximum supersaturation degree of the dye solution (10) is 10
Or more, preferably 100 or more, more preferably 100
It is desirable to set the condition to be 0 or more.

The above-mentioned examples can be given as the method for precipitating crystals, but a method of mixing the dye solution with a new solvent or quenching the dye solution is preferable from the viewpoint of easy control of the particle size.

By adding a small amount of a compound having a similar structure to the dye and having only some of the substituents and dissolving it, crystal growth is suppressed when crystals of the dye are precipitated, or the dye crystal is stopped midway, and the particle size is smaller. Fine dye particles can be obtained.

It is preferable that the dye solution is sent to the mixing device by high pressure gas. A new solvent feeding device is not particularly limited.

In the method of precipitating crystals by mixing the solution with a new solvent, it is advisable to add a new surfactant to the dispersion after crystal precipitation for long-term storage and maintaining dispersion stability against increase in liquid temperature. .

The BET (specific surface area) of the dye solid fine particles of the silver halide photographic light-sensitive material is 10 m ² / g or more, preferably 20 m ² / g or more, more preferably 30 m ² / g.
It is desirable to use the above.

[0077]

EXAMPLES The method for producing dye solid fine particles will be described below as examples of the present invention, but the present invention is not limited thereto.

Example 1 The results of the experiments carried out using a sparingly soluble organic dye having a solubility in acetone at the boiling point of 8 × 10 ⁻⁵ g / ml are shown below.

(Preparation of Sample) Liquid A completely dissolved at 130 ° C. in a nitrogen gas-purged pressure vessel was pressurized to 4 atm of high-pressure gas, and liquid B described below was pressurized to 3 atm of nitrogen gas to a static mixer. And mixed instantaneously at a mixing flow rate of 6 m / sec to deposit solid fine particles of the dye.

Further, 0.1 g of an anionic surfactant was added to the fine dye particle dispersion for long-term storage and improvement of thermal stability.

Liquid A Organic dye 0.5 g Nonionic surfactant 0.1 g Acetone 50 ml Liquid B Pure water (5 ° C.) 1300 ml The above liquid A was completely dissolved at 130 ° C. in a pressure vessel purged with nitrogen gas. The solution was rapidly cooled by pouring cold water into the jacket of the melting tank and the cooling coil inside the tank under high speed stirring of 1000 rpm, and by rapidly leaking the high-pressure gas in the melting tank, solid fine particles of the dye were deposited.

130 ° C. in a pressure vessel purged with nitrogen gas
The above solution A was completely dissolved, and the solution was sprayed and dried with a high-pressure gas in a kettle depressurized by an aspirator to deposit solid fine particles of the dye. Then, acetone was evaporated and removed under reduced pressure.

130 ° C. in a pressure vessel purged with nitrogen gas
The following solution C completely dissolved in 4 atm of high pressure gas and the following solution D of 3 atm of nitrogen gas were sent to a static mixer under pressure and mixed instantaneously at a mixing flow rate of 6 m / sec to precipitate fine particles of dye. It was Further, 0.1 g of an anionic surfactant activator was added to the dye fine particle dispersion for long-term storage and improvement of thermal stability.

Liquid C Organic dye 0.5 g Nonionic surfactant 0.1 g Acetone 50 ml Organic dye similar structure compound 0.01 g Liquid D Pure water (5 ° C.) 1300 ml Organic dye and surfactant, pure water, diameter 2 mm glass beads Was placed in a container and stirred at 2000 rpm for 5 hours.

Organic dye 6.4 g Nonionic surfactant 1.36 g Pure water 72.24 ml (Preparation of coating liquid) Preparation of dispersion liquid (invention) The solution is heated to 50 ° C. and magnetic stirrer for 1 hr.
The gelatin was completely dissolved by stirring to prepare a coating solution having a dye concentration of 0.14 wt%.

Acetone was removed from the dispersion liquid by vacuum distillation. Dispersion liquid (dye 0.15 wt%) 121.9 ml Gelatin 4.54 g Citric acid aqueous solution (citric acid 5 wt%) 0.11 ml Dispersion liquid ) Organic dye solid fine particles 0.18 g Gelatin 4.54 g Aqueous citric acid solution (citric acid 5 wt%) 0.11 ml Pure water 119.8 ml Preparation of dispersion liquid (comparative) The solution was heated to 50 ° C. for 1 h with a magnetic stirrer.
r Stir to completely dissolve gelatin, and dye concentration 0.14wt%
Was prepared.

Dye dispersion liquid 8 wt%) 2.25 ml Gelatin 4.54 g Citric acid aqueous solution (citric acid 5 wt%) 0.11 ml Pure water 117.6 ml Polyethylene terephthalate base prepared by the above method A coated sample was prepared by coating the above with a wire bar and allowing to stand and dry at room temperature. The following evaluations were performed on the obtained dispersion and the coated sample.

(Evaluation Method) <BET (Specific Surface Area) Measuring Method> The dispersion liquid was repeatedly filtered under reduced pressure with a membrane filter (0.1 μ) manufactured by Advantech Co., Ltd., and a filter layer retaining pore diameter was obtained by a cake layer formed on the membrane filter. The following fine particles were also collected without leakage. The fine particles collected by filtration were dried together with the filter at about 70 ° C. for 8 hours.

The completely dried sample was measured with a BET measuring instrument (Shimadzu Flowsorb 2300) using nitrogen / helium (3: 7 vo).
The mixed gas of l) was used to perform degassing treatment at 110 ° C. for 15 minutes, and then the BET one-point method was used for measurement.

<Measurement method of particle size> Particle size distribution measuring device by dynamic light scattering method (Malvern Autonizer 4700)
At, the particle size of the dispersion was measured.

<Measurement of Contamination> Impurities in the dispersion were measured by XMA. In this example, the comparative sample was markedly contaminated with Si by the glass beads.

<Measurement Method of Coating Sample Absorption Performance> The absorption spectrum of the coating sample at 700 to 250 nm was measured with a transmission spectrophotometer, and the absorbance at 545 nm was evaluated as the absorption performance.

<Measurement of Dye Adhesion Amount of Coated Sample> In order to confirm whether there is a difference in the amount of dye adhering to the sample after coating,
The dye was dissolved from the coated sample using a weakly basic solvent, and the absorbance of the solution was measured with a spectrophotometer. The above measurement results are summarized in Table 1 below.

[0094]

[Table 1]

As is clear from the table, according to the present invention, fine particles equivalent to or more than those of mechanically pulverized products such as a mill were obtained.
Further, it can be seen that, unlike the obtained fine particle milling method, there is no contamination and the light absorption performance is higher than that of the milled product.

[0096]

As demonstrated by the examples, according to the present invention, it is possible to provide a method for producing solid fine particles free from contamination, excellent in purity and equivalent to or better than mechanically pulverized products such as a mill.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01D 9/02 603 9344-4D B01D 9/02 603B 9344-4D 603H G03C 1/06 502 G03C 1 / 06 502 1/83 1/83

Claims (7)

[Claims] 1. A method for producing solid fine particles, which comprises dissolving the compound in a solvent to precipitate solid fine particles of the compound, wherein the compound is dissolved in the solvent under conditions of high temperature and pressure. 2. The method for producing solid fine particles according to claim 1, wherein the compound is a poorly soluble compound in a solvent. 3. The method for producing solid fine particles according to claim 1, wherein the compound is dissolved in a solvent together with a surfactant. 4. The method for producing solid fine particles according to claim 1, wherein the solid fine particles are precipitated by mixing the compound solution and a new solvent. 5. The method for producing solid fine particles according to claim 1, wherein the solid fine particles are precipitated by cooling the compound solution. 6. The method for producing solid fine particles according to claim 1, wherein the solid fine particles are precipitated by evaporating the solvent of the compound solution. 7. The specific surface area (BET) of the solid fine particles is 10 m ^2.
It is / g or more, The manufacturing method of the solid fine particles of Claim 1 characterized by the above-mentioned.