Method for producing liquid crystalline resin microparticles

Abstract

Provided is a new method for producing liquid crystalline resin microparticles.　A method for producing liquid crystalline resin microparticles according to the present invention includes subjecting a raw material compound containing one or more selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof to a polycondensation reaction in an organic solvent in the presence of a vinylpyrrolidone copolymer. The blending amount of the raw material compound is 0.5-40 mass% of the total amount (100 mass%) of the raw material compound, the organic solvent, and the vinylpyrrolidone copolymer.

Description

Method for producing liquid crystalline resin particles

[0001] The present disclosure relates to a method for producing liquid crystalline resin particles.

[0002] Liquid crystalline resins have high rigidity and elasticity, as well as excellent heat resistance, impact resistance, and chemical resistance. Therefore, liquid crystalline resin microparticles are expected to be used as coating materials, powder materials for producing molded bodies, and additives in fields requiring heat resistance and mechanical strength. Spherical, small-diameter liquid crystalline resin microparticles are particularly sought after. Pulverization and polymer blending are known methods for producing liquid crystalline resin microparticles. Pulverization involves physical pulverization, resulting in fibrous (fibril) microparticles, making it difficult to obtain spherical microparticles. Polymer blending is a method for producing liquid crystalline resin microparticles by melt-mixing a liquid crystalline resin with a solvent-soluble matrix resin, followed by dissolving and removing the matrix resin with the solvent. Polymer blending requires the use of a large amount of matrix resin and numerous steps, such as mixing with and separating the matrix resin. Patent Document 1 describes a method for producing spherical liquid crystalline resin microparticles by melt-mixing a liquid crystalline resin with a specific matrix resin.

[0003] International Publication No. 2019 / 240153

[0004] An object of the present disclosure is to provide a novel method for producing liquid crystalline resin particles.

[0005] The production method according to the present embodiment is a method for producing liquid crystalline resin microparticles, which comprises polycondensation reaction of raw material compounds containing one or more selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof in an organic solvent and in the presence of a vinylpyrrolidone copolymer, and the blending amount of the raw material compounds is 0.5 to 40% by mass based on the total amount (100% by mass) of the raw material compounds, the organic solvent, and the vinylpyrrolidone copolymer.

[0006] According to the present disclosure, a novel method for producing liquid crystalline resin fine particles can be provided.

[0007] 1 is an electron microscope photograph of liquid crystalline resin particles obtained in Example 7.

[0008] An embodiment of the present disclosure will be described in detail below. However, the scope of the present disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present disclosure. Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. Furthermore, when multiple upper and lower limit values ​​are described for a specific parameter, any of these upper and lower limit values ​​can be combined to form a suitable numerical range. Furthermore, the lower and / or upper limit values ​​of a numerical range described in this disclosure are numerical values ​​within that numerical range and may be replaced with numerical values ​​shown in the examples. The expression "X to Y" indicating a numerical range means "X or more and Y or less." If a specific description described for one embodiment also applies to other embodiments, that description may be omitted in other embodiments.

[0009] [Method for producing liquid crystalline resin microparticles] An embodiment of the present disclosure relates to a method for producing liquid crystalline resin microparticles. The method for producing liquid crystalline resin microparticles according to this embodiment comprises subjecting raw material compounds, including one or more selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof, to a polycondensation reaction in an organic solvent in the presence of a vinylpyrrolidone copolymer, wherein the amount of the raw material compounds is 0.5 to 40% by mass based on the total amount (100% by mass) of the raw material compounds, the organic solvent, and the vinylpyrrolidone copolymer.

[0010] The present inventors have conducted extensive research and discovered a novel, simplified method for producing liquid crystalline resin microparticles. More specifically, they have discovered that liquid crystalline resin microparticles can be produced by polycondensation of raw material compounds containing at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids and their polymerizable derivatives in an organic solvent in the presence of a vinylpyrrolidone copolymer, and that small, spherical liquid crystalline resin microparticles can be synthesized, leading to the completion of the present disclosure. The method for producing liquid crystalline resin microparticles of this embodiment eliminates the need to use large amounts of resins other than the liquid crystalline resin, and eliminates the need for numerous steps such as mixing and separation, making it possible to produce small, spherical liquid crystalline resin microparticles.

[0011] As used herein, "liquid crystalline" means having the property of being able to form an optically anisotropic melt phase. The properties of the anisotropic melt phase can be confirmed by a conventional polarization examination method using crossed polarizers. The anisotropic melt phase can be confirmed, for example, by using a Leitz polarizing microscope to observe a molten sample placed on a Leitz hot stage at 40x magnification under a nitrogen atmosphere. When a resin having liquid crystallinity is examined between crossed polarizers, polarized light usually passes through, even in a molten, stationary state, and the resin exhibits optical anisotropy.

[0012] <Raw Material Compound> In this embodiment, the raw material compound includes one or more compounds selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof. In this disclosure, "polymerizable derivative" refers to a compound whose molecular structure has been partially changed and that can be polymerized by melt polymerization. Examples include acylated compounds in which a phenolic hydroxyl group and / or an amino group is acylated with an acylating agent, halides in which one or more hydrogen atoms of an aromatic hydrocarbon group are substituted with a halogen atom, acid halides in which a carboxyl group is halogenated with a halogenating agent, acid anhydrides, and alkyl esters (having approximately 1 to 4 carbon atoms).

[0013] The aromatic hydroxycarboxylic acid and its polymerizable derivative are not particularly limited, and examples thereof include 4-hydroxybenzoic acid (HBA), 6-hydroxy-2-naphthoic acid (HNA), 3-hydroxybenzoic acid, 6-hydroxy-3-naphthoic acid, 6-hydroxy-4-naphthoic acid, 4-hydroxy-4'-carboxydiphenyl ether, 2,6-dichloro-p-hydroxybenzoic acid, 2-chloro-p-hydroxybenzoic acid, 2,6-dimethyl-p-hydroxybenzoic acid, 2,6-difluoro-p-hydroxybenzoic acid, 4-hydroxy-4'-biphenylcarboxylic acid, and vanillic acid. At least one compound selected from these can be used. Among these, it is preferable to use at least one compound selected from 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid because of their ease of availability.

[0014] The amount of the aromatic hydroxycarboxylic acid and its polymerizable derivative is preferably 40 to 100 mol %, more preferably 45 to 100 mol %, even more preferably 50 to 100 mol %, and particularly preferably 55 to 100 mol %, based on the total amount of the raw material compounds.

[0015] In one embodiment, one or more of the raw material compounds may be an acylated product in which a phenolic hydroxyl group and / or an amino group is acylated with an acylating agent. The acylation reaction will be described later. Examples of aromatic hydroxycarboxylic acids in which a phenolic hydroxyl group is acylated include 4-acetoxybenzoic acid (ABA), 6-acetoxy-2-naphthoic acid (ANA), 3-acetoxybenzoic acid, 6-acetoxy-3-naphthoic acid, and 6-acetoxy-4-naphthoic acid. Among these, in terms of ease of availability, it is preferable to use at least one selected from 4-acetoxybenzoic acid (ABA) and 6-acetoxy-2-naphthoic acid (ANA).

[0016] In one embodiment, the raw material compound is preferably at least one selected from 4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4-acetoxybenzoic acid (ABA), and 6-acetoxy-2-naphthoic acid (ANA). The raw material compound preferably further satisfies the following (1) or (2): (1) it contains at least one compound selected from the group consisting of aromatic or alicyclic dicarboxylic acids and polymerizable derivatives thereof, or (2) it contains at least one compound selected from the group consisting of aromatic or alicyclic dicarboxylic acids and polymerizable derivatives thereof, and at least one compound selected from the group consisting of aromatic or alicyclic diols, aromatic or alicyclic hydroxyamines, aromatic or alicyclic diamines, and polymerizable derivatives thereof.

[0017] The aromatic dicarboxylic acid is not particularly limited, and examples thereof include terephthalic acid (TA), isophthalic acid, 4,4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and compounds represented by the following general formula (I): (Y:-(CH ２) ｎ -(n=1 to 4) and -O(CH ２ ) ｎ O- (n = 1 to 4).

[0018] The alicyclic dicarboxylic acid is not particularly limited, and examples thereof include 1,4-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, etc. The polymerizable derivative is not particularly limited, and examples thereof include alkyl esters (having about 1 to 4 carbon atoms) and halides of the above compounds.

[0019] The total amount of at least one compound selected from the group consisting of aromatic or alicyclic dicarboxylic acids and polymerizable derivatives thereof is preferably 0 to 30 mol %, more preferably 0 to 25 mol %, based on the total amount of raw material compounds.

[0020] The aromatic diol is not particularly limited, and examples thereof include 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4′-dihydroxybiphenyl (BP), hydroquinone, resorcinol, a compound represented by the following general formula (II), and a compound represented by the following general formula (III).

[0021] General formula (II): (X: alkylene (C １ ~C ４ ), alkylidene, —O—, —SO—, —SO ２ is a group selected from —, —S—, and —CO—.

[0022] General formula (III):

[0023] The alicyclic diol is not particularly limited, and examples thereof include 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, etc. The polymerizable derivative is not particularly limited, and examples thereof include alkyl esters (having about 1 to 4 carbon atoms) and halides of the above compounds.

[0024] The aromatic hydroxyamine is not particularly limited, and examples thereof include N-acetyl-p-aminophenol (APAP), 4-aminophenol, 3-aminophenol, etc. The alicyclic hydroxyamine is not particularly limited, and examples thereof include 4-aminocyclohexanol, 3-aminocyclopentanol, etc. The polymerizable derivative is not particularly limited, and examples thereof include alkyl esters (having about 1 to 4 carbon atoms) and halides of the above compounds.

[0025] Examples of aromatic diamines include 1,4-phenylenediamine. Examples of alicyclic diamines include, but are not limited to, 1,4-cyclohexanediamine, 1,3-cyclopentanediamine, etc. Examples of polymerizable derivatives include, but are not limited to, alkyl esters (having about 1 to 4 carbon atoms) and halides of the above compounds.

[0026] The total amount of at least one compound selected from the group consisting of aromatic or alicyclic diols, aromatic or alicyclic hydroxyamines, aromatic or alicyclic diamines, and polymerizable derivatives thereof is preferably 0 to 30 mol %, more preferably 0 to 25 mol %, based on the total amount of raw material compounds.

[0027] Specific combinations of raw material compounds can be selected from the following: (I) (Ia) at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof (preferably consisting of at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof); (II) (IIa) at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof, (IIb) at least one compound selected from the group consisting of aromatic or alicyclic dicarboxylic acids and polymerizable derivatives thereof, and (IIc) at least one compound selected from the group consisting of aromatic or alicyclic diols, aromatic hydroxyamines, aromatic diamines, and polymerizable derivatives thereof (preferably consisting of the above compound (IIa), compound (IIb), and compound (IIc)); Furthermore, a molecular weight modifier may be used in combination with the above components, if necessary.

[0028] Various catalysts can be used in the polymerization. Typical usable catalysts include metal salt catalysts such as potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, antimony trioxide, and tris(2,4-pentanedionato)cobalt(III); organic compound catalysts such as N-methylimidazole and 4-dimethylaminopyridine; and onium salt catalysts such as tetraphenylphosphonium bromide. The amount of catalyst used is generally preferably 0.001 to 1 mass%, and more preferably 0.01 to 0.2 mass%, of the total mass (100 mass%) of the raw material compounds.

[0029] <Amount of Raw Material Compounds> In this embodiment, the amount of raw material compounds is 0.5 to 40% by mass based on the total amount (100% by mass) of the raw material compounds, organic solvent, and vinylpyrrolidone copolymer. In the present disclosure, the "amount of raw material compounds" is defined as follows: Amount of raw material compounds (% by mass) = (mass of raw material compounds) / (mass of raw material compounds + mass of organic solvent + mass of vinylpyrrolidone copolymer) × 100. By setting the amount of raw material compounds to 0.5 to 40% by mass based on the total amount (100% by mass) of the raw material compounds, organic solvent, and vinylpyrrolidone copolymer, it is possible to produce liquid crystalline resin microparticles using a more simplified method. In addition, liquid crystalline resin microparticles with a smaller particle size are more likely to be obtained. Furthermore, liquid crystalline resin microparticles are more likely to be obtained in a high yield. From the perspective of particle size, the smaller the amount of raw material compounds, the more likely liquid crystalline resin microparticles with a smaller particle size are to be obtained. It is presumed that the reduction in primary particle size and the reduction in particle number reduces the frequency of particle collisions, thereby suppressing particle collision-induced particle growth and making it easier to obtain liquid crystalline resin microparticles with a smaller particle size. In one embodiment, the blending amount of the raw material compound is preferably 0.5 to 35% by mass, more preferably 0.5 to 30% by mass, even more preferably 0.5 to 25% by mass, and particularly preferably 1 to 20% by mass, based on the total amount (100% by mass) of the raw material compound, organic solvent, and vinylpyrrolidone copolymer. In one embodiment, the blending amount of the raw material compound may be 0.5 to 10% by mass, or may be more than 10% by mass and not more than 22% by mass, based on the total amount (100% by mass) of the raw material compound, organic solvent, and vinylpyrrolidone copolymer.

[0030] <Vinylpyrrolidone Copolymer> In this embodiment, the incorporation of a vinylpyrrolidone copolymer facilitates the polycondensation reaction, enabling the production of liquid crystalline resin microparticles by a simplified method. Furthermore, polymer aggregation in the reaction system is easily suppressed, making it easier to obtain liquid crystalline resin microparticles with a high yield. In this embodiment, the "vinylpyrrolidone copolymer" is a copolymer of vinylpyrrolidone and a compound copolymerizable with vinylpyrrolidone. The compound (monomer) copolymerizable with vinylpyrrolidone is not particularly limited, but examples include α-olefins and styrene. In one embodiment, the vinylpyrrolidone copolymer preferably contains one or more selected from the group consisting of α-olefin-vinylpyrrolidone copolymers and styrene-vinylpyrrolidone copolymers. The α-olefin constituting the α-olefin-vinylpyrrolidone copolymer preferably has 12 to 40 carbon atoms, such as hexadecene, eicosene, and triacontene. Commercially available eicosene-vinylpyrrolidone copolymers include ANTARON V-220 and GANEX V-220 (both manufactured by ISP), and UNIMER U-15 (manufactured by INDUCHEM). An example of a commercially available hexadecene-vinylpyrrolidone copolymer is ANTARON V-216 (manufactured by ISP), and an example of a commercially available triacontanyl-vinylpyrrolidone copolymer is ANTARON WP-600 (manufactured by ISP). Examples of styrene-vinylpyrrolidone copolymers include Antara 430 (manufactured by ISP) and Polectron 430 (manufactured by ISP). In one embodiment, the vinylpyrrolidone copolymer preferably contains an α-olefin-vinylpyrrolidone copolymer.

[0031] In one embodiment, the blending amount of the vinylpyrrolidone copolymer is preferably 0.05 to 10% by mass, more preferably 0.05 to 8% by mass, even more preferably 0.05 to 6% by mass, and particularly preferably 0.05 to 5% by mass, based on the total amount (100% by mass) of the raw material compounds, organic solvent, and vinylpyrrolidone copolymer. In the above embodiment, the blending amount of the vinylpyrrolidone copolymer is defined as follows: Blending amount of vinylpyrrolidone copolymer (% by mass) = (mass of vinylpyrrolidone copolymer) / (mass of raw material compounds + mass of organic solvent + mass of vinylpyrrolidone copolymer) × 100. When the blending amount of the vinylpyrrolidone copolymer is within the above range, the polycondensation reaction proceeds more easily, enabling the production of liquid crystalline resin microparticles by a more simplified method. Furthermore, polymer aggregation in the reaction system is further suppressed, making it easier to obtain liquid crystalline resin microparticles in a high yield.

[0032] <Organic Solvent> In this embodiment, the organic solvent is not limited as long as it does not dissolve the polymer produced by the polycondensation reaction. In one embodiment, the organic solvent is preferably an organic solvent with a high boiling point or high decomposition temperature. In one embodiment, the boiling point or decomposition temperature of the organic solvent is preferably 250°C or higher, more preferably 260°C or higher, even more preferably 270°C or higher, and particularly preferably 280°C or higher. When the organic solvent has the above-mentioned high boiling point, the polycondensation reaction can be carried out at a high temperature, making it easier to obtain spherical liquid crystalline resin microparticles. In one embodiment, the organic solvent is preferably one or more organic solvents selected from the following: hydrocarbon solvents: liquid paraffin, hydrogenated triphenyl, dibenzyltoluene, diethylbiphenyl, triethylbiphenyl, cyclohexylbiphenyl, diisopropylnaphthalene, diethylnaphthalene, ethyl-isopropylnaphthalene, dialkylbenzene, alkylnaphthalene; ether solvents: diphenyl ether, dibenzyl ether; polar solvent: diphenyl sulfone; and liquid salts (ionic liquids) composed of cations and anions that melt at the temperature of use: phosphonium salts such as tributylmethylphosphonium bis(trifluoromethanesulfonyl)imide, sulfonium salts such as triethylsulfonium bis(trifluoromethanesulfonyl)imide, ammonium salts such as tributylmethylammonium bis(trifluoromethanesulfonyl)imide, and imidazolium salts such as 1,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide.

[0033] <Polycondensation Reaction> In this embodiment, the method includes subjecting a raw material compound containing one or more selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof to a polycondensation reaction in an organic solvent in the presence of a vinylpyrrolidone copolymer.

[0034] The polycondensation temperature is preferably 200 to 400°C, more preferably 240 to 380°C, even more preferably 280 to 380°C, and particularly preferably 300 to 360°C. The polycondensation reaction time is preferably 2 to 12 hours, more preferably 3 to 10 hours, and even more preferably 4 to 8 hours. The temperature rise rate is not particularly limited, but from the perspective of particle size, a faster temperature rise rate is more likely to produce liquid crystalline resin microparticles with smaller particle sizes. This shortens the time required to reach the molecular weight at which the liquid-to-solid phase transition occurs, making it less likely that particles will become giant due to collisions in the liquid state, and thus making it easier to obtain liquid crystalline resin microparticles with smaller particle sizes. After the polycondensation reaction is completed, the suspension is filtered using a filter or the like to recover the insoluble matter, and the insoluble matter is further dried as necessary to obtain liquid crystalline resin microparticles. In one embodiment, the polycondensation reaction may be carried out with stirring.

[0035] (Acylation Step) In one embodiment of the production method, acylation of the raw material compounds may be included before the polycondensation reaction. Examples of the acylating agent include, but are not limited to, acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, pivalic anhydride, 2-ethylhexanoic anhydride, monochloroacetic anhydride, dichloroacetic anhydride, trichloroacetic anhydride, monobromoacetic anhydride, dibromoacetic anhydride, tribromoacetic anhydride, monofluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, glutaric anhydride, maleic anhydride, succinic anhydride, and β-bromopropionic anhydride. At least one selected from these can be used. Preferred examples from the standpoint of cost and handleability include carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and isobutyric anhydride. Among these, acetic anhydride is preferred from the standpoint of ease of availability. The amount of the acylating agent used is preferably 1.0 to 1.1 equivalents, more preferably 1.01 to 1.1 equivalents, based on the total amount of hydroxyl groups in the substances used in the reaction, from the viewpoint of ease of reaction control. Acylation can be carried out by known methods. For example, the raw material compound is mixed with the acylating agent and heated at a temperature range of 120 to 160°C for about 0.5 to 5 hours to carry out the acylation reaction, thereby obtaining a reaction product containing an acylated product.

[0036] In one embodiment, the polycondensation reaction may be carried out under a predetermined reduced pressure by initiating decompression after the reaction system has reached a predetermined temperature. In one embodiment, it is preferable to start decompression after the reaction system has reached the final polymerization temperature and to carry out the reaction at a predetermined reduced pressure. In one embodiment, the polycondensation reaction is preferably carried out under a reduced pressure of 100 to 400 Torr, more preferably under a reduced pressure of 150 to 350 Torr, and even more preferably under a reduced pressure of 150 to 300 Torr. By starting decompression after the reaction system has reached a predetermined temperature and carrying out the polycondensation reaction under a predetermined reduced pressure, the particle size of the resulting liquid crystalline resin microparticles becomes smaller.

[0037] <Liquid Crystalline Resin Particles> The liquid crystalline resin particles mainly contain a liquid crystalline resin and are substantially spherical. In the present disclosure, "mainly contain" means that the liquid crystalline resin content in the liquid crystalline resin particles is 60% by mass or more, and the liquid crystalline resin content in the liquid crystalline resin particles is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 98% by mass or more. By being in the above range, it is possible to obtain resin particles with a low content of other resin components as impurities or substantially no resin components, and to obtain a powder material having various excellent properties possessed by the liquid crystalline resin, such as heat resistance, impact resistance, and chemical resistance.

[0038] In the present disclosure, "fine particles" refers to particles having an average particle diameter of approximately 0.1 μm to 100 μm. In the present disclosure, "average particle diameter" refers to the arithmetic average particle diameter on a volume basis measured by a laser diffraction / scattering particle size distribution measurement method. The average particle diameter can be measured using a laser diffraction / scattering particle size distribution measurement device. In one embodiment, the average particle diameter of the liquid crystalline resin fine particles is preferably 0.5 μm to 100 μm, more preferably 0.5 μm to 60 μm, even more preferably 0.5 μm to 40 μm, and particularly preferably 0.5 μm to 20 μm. According to the production method of this embodiment, liquid crystalline resin fine particles having an average particle diameter of 0.5 μm to 100 μm can be obtained, and the fine particles can be suitably used in various applications such as coating materials, powder materials for producing molded bodies, and additives. Furthermore, according to the production method of this embodiment, spherical liquid crystalline resin microparticles can be obtained, and therefore liquid crystalline resin microparticles with excellent powder fluidity can be obtained, and can be suitably used for various applications such as coating materials, powder materials for producing molded bodies, and additives.

[0039] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure is disclosed below. [1] A method for producing liquid crystalline resin microparticles, comprising: carrying out a polycondensation reaction of raw material compounds containing one or more selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof in an organic solvent and in the presence of a vinylpyrrolidone copolymer while stirring, wherein the amount of the raw material compounds is 0.5 to 40% by mass (preferably 0.5 to 35% by mass, more preferably 0.5 to 30% by mass, even more preferably 0.5 to 25% by mass, and particularly preferably 1 to 20% by mass) based on the total amount (100% by mass) of the raw material compounds, the organic solvent, and the vinylpyrrolidone copolymer. [2] The production method according to [1], wherein the vinylpyrrolidone copolymer contains one or more selected from the group consisting of an α-olefin-vinylpyrrolidone copolymer and a styrene-vinylpyrrolidone copolymer. [3] The manufacturing method according to [1] or [2], wherein the blending amount of the vinylpyrrolidone copolymer is 0.05 to 10% by mass (preferably 0.05 to 8% by mass, more preferably 0.05 to 6% by mass, and even more preferably 0.05 to 5% by mass) based on the total amount (100% by mass) of the raw material compounds, the organic solvent, and the vinylpyrrolidone copolymer. [4] The manufacturing method according to any one of [1] to [3], wherein the boiling point or decomposition temperature of the organic solvent is 250°C or higher. [5] The manufacturing method according to any one of [1] to [4], wherein the liquid crystalline resin microparticles have a volume-based 50% average particle size of 0.5 μm to 100 μm as measured by a laser diffraction / scattering method. [6] The manufacturing method according to any one of [1] to [5], wherein the liquid crystalline resin microparticles have a volume-based 50% average particle size of 0.5 μm to 20 μm as measured by a laser diffraction / scattering method. [7] The manufacturing method according to any one of [1] to [6], wherein the raw material compounds are acylated before the polycondensation reaction. [8] The method according to any one of [1] to [7], wherein the polycondensation reaction is carried out under a reduced pressure of 100 to 400 Torr.

[0040] The present disclosure will be explained in more detail below by showing examples, but interpretation of the present disclosure is not limited to these examples.

[0041] Example 1 The following raw material compounds, organic solvent, and vinylpyrrolidone copolymer were charged into a polymerization vessel equipped with a stirrer, and the temperature of the reaction system was then raised from room temperature (23°C) to 140°C over 30 minutes. The temperature of the reaction system was then further raised to 320°C (final polymerization temperature) over 3.0 hours, and polymerization was carried out at 320°C (final polymerization temperature) for 30 minutes (polycondensation reaction). The reaction system was cooled to room temperature, and the suspension was recovered, washed with toluene and hexane, and filtered to obtain liquid crystalline resin microparticles. When these microparticles were observed with an electron microscope (ultra-deep multi-angle microscope, KEYENCE Corporation, "VHX-D510"), spherical microparticles were observed. Furthermore, liquid crystallinity was confirmed by observation with a polarizing microscope. Raw material compounds: 9% by mass; 4-acetoxybenzoic acid (ABA): 20.5 g (73 mol%); 6-acetoxy-2-naphthoic acid (ANA): 9.7 g (27 mol%); Organic solvent; Dialkylbenzene (A): 300 g; Vinylpyrrolidone copolymer: 0.5% by mass; (VP / eicosene) copolymer (VP / E): 1.7 g

[0042] [Examples 2-7, Comparative Examples 1 and 2] Liquid crystalline resin particles were obtained in the same manner as in Example 1, except that the types and proportions of raw material compounds, organic solvents, and vinylpyrrolidone copolymers, and whether or not a decompression step was performed, were as shown in Table 1, and the final polymerization temperature was as follows.

[0043] [Examples 8-10] Liquid crystalline resin particles were obtained in the same manner as in Example 1, except that the types and proportions of raw material compounds, organic solvents, and vinylpyrrolidone copolymers, and whether or not a pressure reduction step was performed, were as shown in Table 1, the final polymerization temperature was as shown below, and the temperature increase time from 140°C to the final polymerization temperature was 4 hours.

[0044] [Example 12] The following raw material compounds, organic solvent, vinylpyrrolidone copolymer, and acylating agent were charged into a polymerization vessel equipped with a stirrer, and the temperature of the reaction system was raised from room temperature (23°C) to 140°C over 30 minutes, and the reaction was carried out at 140°C for 1 hour (acylation reaction). The temperature was then further raised to 325°C (final polymerization temperature) over 3.0 hours, and polymerization was carried out at 325°C (final polymerization temperature) for 30 minutes (polycondensation reaction). The reaction system was cooled to room temperature, and the suspension was recovered, washed with toluene and hexane, and filtered to obtain liquid crystalline resin microparticles. Raw materials: 9% by mass; 4-hydroxybenzoic acid (HBA): 20.0 g (73 mol%); 6-hydroxy-2-naphthoic acid (HNA): 10.1 g (27 mol%); Organic solvent: Alkylnaphthalene (C): 300 g; Vinylpyrrolidone copolymer: 0.5% by mass; (VP / eicosene) copolymer (VP / E): 1.7 g; Acylating agent: Acetic anhydride (AA): 22.3 g (1.1 times the total hydroxyl group equivalent of HBA and HNA)

[0045] [Examples 13-14] Liquid crystalline resin particles were obtained in the same manner as in Example 12, except that the types and proportions of raw material compounds, organic solvents, and vinylpyrrolidone copolymers, and whether or not a pressure reduction step was performed, were as shown in Table 2, the final polymerization temperature was as shown below, the heating time from 140°C to the final polymerization temperature was 3.0 hours, and polymerization was carried out at the final polymerization temperature for 180 minutes.

[0046] Example 15 Liquid crystalline resin particles were obtained in the same manner as in Example 14, except that the temperature rise time from 140° C. to the final polymerization temperature was changed to 2.0 hours.

[0047] In Table 1, the "amount of raw material compounds" and the "amount of vinylpyrrolidone copolymer" are defined as follows: Amount of raw material compounds (% by mass) = (mass of raw material compounds) / (mass of raw material compounds + mass of organic solvent + mass of vinylpyrrolidone copolymer) x 100 Amount of vinylpyrrolidone copolymer (% by mass) = (mass of vinylpyrrolidone copolymer) / (mass of raw material compounds + mass of organic solvent + mass of vinylpyrrolidone copolymer) x 100 In Table 1, the presence or absence of a "pressure reduction step" refers to the presence or absence of a step in which, after the final polymerization temperature is reached, the reaction system is reduced in pressure to 300 Torr while maintaining the temperature, and the reaction is carried out under reduced pressure for 30 minutes. In Table 1, the "yield of liquid crystalline resin microparticles" refers to the yield relative to the theoretical yield of the polymer obtained from the raw material compounds.

[0048] (Raw material compounds) ABA: 4-acetoxybenzoic acid HBA: 4-hydroxybenzoic acid ANA: 6-acetoxy-2-naphthoic acid HNA: 6-hydroxy-2-naphthoic acid TA: terephthalic acid (Organic solvents) A: Dialkylbenzene (boiling point: 385°C) B: Liquid paraffin (boiling point: 300°C or higher) C: Alkylnaphthalene (boiling point: 430°C) (Vinylpyrrolidone copolymer) VP / E: (VP / eicosene) copolymer (Acylating agent) AA: Acetic anhydride (Final polymerization temperature) Examples 1-3, 11, Comparative Example 2: 320°C Examples 4-7, 12, Comparative Example 1: 325°C Examples 8-10: 350°C Examples 13-15: 300°C

[0049] (Average particle size) 50 mg of each liquid crystalline resin fine particle was placed in 1 mL of acetone and dispersed for about 3 minutes using an ultrasonic disperser to obtain a dispersion. For each dispersion, the particle size distribution was measured using a laser diffraction / scattering particle size distribution analyzer (manufactured by Horiba, Ltd., "LA-960") to determine the average particle size of the liquid crystalline resin fine particles in the dispersion.

[0050]

[0051]

[0052] Liquid crystalline resin microparticles were obtained by the manufacturing method of the Examples satisfying the configuration of this embodiment. That is, it can be seen that the manufacturing method of the Examples satisfying the configuration of this embodiment enables the production of liquid crystalline resin microparticles by a novel, simplified method. This means that liquid crystalline resin microparticles can be produced by a method that does not require the use of large amounts of matrix resin, mixing with the matrix resin, melting and removing the matrix resin, and other processes that were previously required in polymer blending. FIG. 1 is an electron microscope photograph of the liquid crystalline resin microparticles of Example 7, which is an example of liquid crystalline resin microparticles obtained by the manufacturing method of the Examples satisfying the configuration of this embodiment. As shown in FIG. 1, it can be seen that spherical liquid crystalline resin microparticles with a very narrow particle size distribution and high sphericity were certainly obtained. This means that the manufacturing method of the Examples allows the production of higher quality spherical liquid crystalline resin microparticles by a simplified method. As shown in Table 1, liquid crystalline resin microparticles were obtained in a high yield in the Examples satisfying the configuration of this embodiment. On the other hand, in Comparative Example 1, which does not satisfy the configuration of this embodiment, no liquid crystalline resin microparticles were obtained, and in Comparative Example 2, only a very small yield of 8% liquid crystalline resin microparticles was obtained. This means that the methods of the examples satisfying the configuration of this embodiment allow for the production of liquid crystalline resin particles with a higher yield using a more simplified and novel production method. Furthermore, surprisingly, the liquid crystalline resin particles obtained by the examples satisfying the configuration of this embodiment have an average particle size of less than 20 μm (the liquid crystalline resin particles obtained in Examples 1-3 and 5-15 have an average particle size of less than 10 μm). It was found that the methods of the examples satisfying the configuration of this embodiment allow for the production of liquid crystalline resin particles with a small average particle size.

[0053] The novel method for producing liquid crystalline resin microparticles of the present embodiment is a simpler method than conventionally known methods and can produce liquid crystalline resin microparticles more efficiently, and therefore can be suitably used in methods for producing liquid crystalline resin microparticles, etc., and has industrial applicability.

Claims

1. A method for producing liquid crystalline resin particles, comprising polycondensing a raw material compound containing one or more compounds selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof in an organic solvent and in the presence of a vinylpyrrolidone copolymer, wherein the blending amount of the raw material compound is 0.5 to 40% by mass based on the total amount (100% by mass) of the raw material compound, the organic solvent, and the vinylpyrrolidone copolymer.

2. The method of claim 1, wherein the vinylpyrrolidone copolymer comprises at least one selected from the group consisting of an α-olefin-vinylpyrrolidone copolymer and a styrene-vinylpyrrolidone copolymer.

3. The method of claim 1 or 2, wherein the blending amount of the vinylpyrrolidone copolymer is 0.05 to 10% by mass based on the total amount (100% by mass) of the raw material compounds, the organic solvent, and the vinylpyrrolidone copolymer.

4. The method according to claim 1 or 2, wherein the boiling point or decomposition temperature of the organic solvent is 250°C or higher.

5. The method according to claim 1 or 2, wherein the liquid crystalline resin particles have a volume-based 50% average particle size of 0.5 μm or more and 100 μm or less as measured by a laser diffraction / scattering method.

6. The method according to claim 1 or 2, wherein the liquid crystalline resin particles have a volume-based 50% average particle size of 0.5 μm or more and 20 μm or less as measured by a laser diffraction / scattering method.

7. The method according to claim 1 or 2, further comprising acylating the starting compound before the polycondensation reaction.

8. The method according to claim 1 or 2, wherein the polycondensation reaction comprises carrying out the reaction under a reduced pressure of 100 to 400 Torr.