CN112334516B

CN112334516B - Method for producing liquid crystalline resin fine particles

Info

Publication number: CN112334516B
Application number: CN201980039894.6A
Authority: CN
Inventors: 田口吉昭; 川崎达也
Original assignee: Polyplastics Co Ltd
Current assignee: Polyplastics Co Ltd
Priority date: 2018-06-14
Filing date: 2019-06-12
Publication date: 2021-12-21
Anticipated expiration: 2039-06-12
Also published as: JPWO2019240153A1; JP6697644B1; TW202000749A; WO2019240153A1; CN114249910B; TWI785251B; CN112334516A; CN114249910A

Abstract

Provided is a method for producing spherical liquid crystalline resin fine particles having high heat resistance and containing few impurities. A method for producing liquid crystalline resin fine particles, comprising the steps of: a melt-mixing step of melt-mixing 100 parts by mass of a liquid crystalline resin A having a melting point of 250 to 370 ℃ and 300 to 900 parts by mass of a thermoplastic resin B, which is incompatible with the liquid crystalline resin A and has a melting point or glass transition point of 80 to 400 ℃, at 280 to 400 ℃ to obtain a composition C; and a washing step of stirring the composition C in a solvent in which the solubility of the liquid crystalline resin A is 1 or less and the solubility of the thermoplastic resin B is 5 or more, the solubility being represented by the mass (g) of the resin dissolved in 100g of the solvent at 40 ℃, and the content of ester bonds and amide bonds in the thermoplastic resin B used in the melt-mixing step being 20 mol% or less in total of all monomer units.

Description

Method for producing liquid crystalline resin fine particles

Technical Field

The present invention relates to a method for producing liquid crystalline resin fine particles.

Background

Spherical resin fine particles are excellent in flowability and adhesion, and therefore are used in various applications such as powder materials for coating, powder materials for producing molded bodies, and additives. Since the liquid crystalline resin has high rigidity and high elasticity and is excellent in heat resistance, impact resistance, chemical resistance and the like, the spherical resin fine particles are expected to be applied to coating materials, powder materials for molded article production, additives and the like in fields where heat resistance, mechanical strength and the like are required.

As a method for producing spherical liquid crystalline resin fine particles (microspheres), a method is known in which a liquid crystalline resin and a matrix resin soluble in a solvent are melt-mixed, and then the matrix resin is dissolved and removed by the solvent. For example, patent document 1 discloses a method for producing microspheres of a liquid crystalline polymer, in which a liquid crystalline polymer and a non-liquid crystalline polymer soluble in a solvent are mixed at a predetermined ratio, heated at a predetermined temperature, extruded, and then dissolved and removed with the solvent. Patent document 2 describes a method for producing liquid crystal polyester microspheres, in which a thermoplastic resin composition containing a thermoplastic resin (a) as a continuous phase and a liquid crystal polyester (B) as a dispersed phase is melt-kneaded, extruded from a nozzle, drawn at a predetermined drawing speed, formed into a strand-like shape, cut into pellets, and the pellets are immersed in a solvent to dissolve and remove the thermoplastic resin.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. H07-003033

Patent document 2: japanese laid-open patent publication No. 2001-064399

Disclosure of Invention

Problems to be solved by the invention

In the conventional production methods, polyethylene terephthalate resins and polycarbonate resins are often used as matrix resins to be melt-mixed with liquid crystalline resins, because they can be melt-kneaded with liquid crystalline resins having high melting points and the liquid crystalline resins can be easily dispersed. However, when a matrix resin having an ester bond and/or an amide bond in its chemical structure is used, impurities generated by the transesterification reaction or the amide exchange reaction may be mixed into the liquid crystalline resin fine particles when melt-mixing is performed at a high temperature exceeding 280 ℃. In addition, it may be difficult to obtain spherical liquid crystalline resin fine particles or the ratio thereof may be small.

The invention provides a method for producing spherical liquid crystalline resin fine particles having high heat resistance and containing few impurities.

Means for solving the problems

The present invention relates to the following.

[1] A method for producing liquid crystalline resin fine particles, comprising the steps of:

a melt-mixing step of melt-mixing 100 parts by mass of a liquid crystalline resin A having a melting point of 250 to 370 ℃ and 300 to 900 parts by mass of a thermoplastic resin B, which is incompatible with the liquid crystalline resin A and has a melting point or glass transition point of 80 to 400 ℃, at 280 to 400 ℃ to obtain a composition C; and a washing step of stirring the composition C in a solvent in which the solubility of the liquid crystalline resin A is 1 or less and the solubility of the thermoplastic resin B is 5 or more, the solubility being represented by the mass (g) of the resin dissolved in 100g of the solvent at 40 ℃, and the content of ester bonds and amide bonds in the thermoplastic resin B used in the melt-mixing step being 20 mol% or less in total of all monomer units.

[2] The production method according to [1], which comprises an extrusion step of forming strands of the composition C using a nozzle-equipped extruder and obtaining pellets after the melt-mixing step and before the washing step,

the product nS (mm) of the number n of nozzle openings of the extruder and the area S of each opening²) The ratio (nS/Q) of the amount of extrusion of the resin per 1 hour to the amount of extrusion of the resin Q (kg/hr) is 20 to 80 inclusive.

[3] The production method according to [1] or [2], wherein the terminal functional group of the thermoplastic resin B is at least one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 or more and 10 or less carbon atoms which may be substituted, an aryl group having 6 or more and 12 or less carbon atoms which may be substituted, an alkoxy group having 1 or more and 10 or less carbon atoms which may be substituted, an aryloxy group having 6 or more and 12 or less carbon atoms which may be substituted, and a vinyl group.

[4] The production method according to any one of [1] to [3], wherein the repeating unit of the chemical structure of the thermoplastic resin B is bonded by any one selected from an ether bond, an alkylene bond, an imide bond, a urethane bond, a sulfide bond and a sulfone bond.

[5] The production method according to any one of [1] to [4], which produces liquid crystalline resin fine particles having an average particle diameter of 1 μm or more and 150 μm or less.

ADVANTAGEOUS EFFECTS OF INVENTION

The present invention can provide a method for producing spherical liquid crystalline resin fine particles having high heat resistance and containing few impurities.

Drawings

FIG. 1 is an electron micrograph of liquid crystalline resin fine particles of example 2.

Detailed Description

Hereinafter, one embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within a range not to impair the effects of the present invention.

The method for producing liquid crystalline resin fine particles (hereinafter also simply referred to as "resin fine particles") according to the present embodiment includes a step of melt-mixing a liquid crystalline resin a and a thermoplastic resin B to obtain a composition C (melt-mixing step), and a step of stirring the obtained composition C in a solvent that does not dissolve the liquid crystalline resin a and dissolves the thermoplastic resin B (cleaning step). After the composition C is obtained, a step of forming pellets of the composition C using an extruder (extrusion step) is optionally provided. In the case of the extrusion step, the pellets obtained in the extrusion step are subjected to a washing step. That is, in the case of the extrusion step, the melt mixing step, the extrusion step, and the washing step are performed in this order.

[ melting and mixing Process ]

In the melt-mixing step, the liquid crystalline resin a and the thermoplastic resin B incompatible with the liquid crystalline resin a are melt-mixed to obtain a composition C including the liquid crystalline resin a and the thermoplastic resin B.

(liquid Crystal resin A)

The liquid crystalline resin a is a thermoplastic resin exhibiting liquid crystallinity, and a known liquid crystalline resin having a melting point of 250 ℃ or higher and 370 ℃ or lower can be used. The melting point is described later. "liquid-crystalline" means having a property of forming an optically anisotropic melt phase. The properties of the anisotropic molten phase can be confirmed by a conventional polarization detection method using an orthogonal polarizer. More specifically, the anisotropic molten phase can be confirmed by observing a molten sample placed on a Leitz hot stage at a magnification of 40 times under a nitrogen atmosphere using a Leitz polarizing microscope. When the cross polarizers are inspected, the liquid crystal resin normally transmits polarized light even in a molten static state, and exhibits optical anisotropy.

The liquid crystalline resin a preferably contains at least 1 selected from a liquid crystalline polyester and a liquid crystalline polyester amide. The liquid crystalline polyester and the liquid crystalline polyester amide are not particularly limited, but preferably an aromatic polyester or an aromatic polyester amide, and more preferably contain at least one resin selected from the group consisting of a wholly aromatic polyester and a wholly aromatic polyester amide. In addition, a polyester partially containing an aromatic polyester or an aromatic polyester amide in the same molecular chain may also be used.

As the aromatic polyester or aromatic polyester amide, an aromatic polyester or aromatic polyester amide having an aromatic hydroxycarboxylic acid as a constituent is particularly preferable.

More specifically, the aromatic polyester or aromatic polyester amide includes:

(1) a polyester mainly comprising 1 or 2 or more species selected from the group consisting of structural units derived from an aromatic hydroxycarboxylic acid and a derivative thereof;

(2) a polyester mainly comprising (a) 1 or 2 or more species selected from the group consisting of constituent units derived from an aromatic hydroxycarboxylic acid and a derivative thereof, and (b) 1 or 2 or more species selected from the group consisting of constituent units derived from an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid, and a derivative thereof;

(3) a polyester mainly comprising (a) 1 or 2 or more species selected from the group consisting of constituent units derived from an aromatic hydroxycarboxylic acid and a derivative thereof, (b) 1 or 2 or more species selected from the group consisting of constituent units derived from an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid, and a derivative thereof, and (c) 1 or 2 or more species selected from the group consisting of constituent units derived from an aromatic diol, an alicyclic diol, an aliphatic diol, and a derivative thereof;

(4) a polyesteramide mainly comprising (a) 1 or 2 or more species selected from the group consisting of structural units derived from an aromatic hydroxycarboxylic acid and a derivative thereof, (b) 1 or 2 or more species selected from the group consisting of structural units derived from an aromatic hydroxylamine, an aromatic diamine, and a derivative thereof, and (c) 1 or 2 or more species selected from the group consisting of structural units derived from an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid, and a derivative thereof;

(5) mainly comprising (a) 1 or 2 or more species selected from the group consisting of structural units derived from aromatic hydroxycarboxylic acids and derivatives thereof, (b) 1 or 2 or more species selected from the group consisting of structural units derived from aromatic hydroxylamines, aromatic diamines, and derivatives thereof, (c) 1 or 2 or more species selected from the group consisting of structural units derived from aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and derivatives thereof, and (d) 1 or 2 or more species selected from the group consisting of structural units derived from aromatic diols, alicyclic diols, aliphatic diols, and derivatives thereof. The liquid crystalline resin a may be used alone or in combination of two or more. Further, a molecular weight modifier may be used in combination with the above-mentioned components as required.

Specific examples of the specific compound (monomer) constituting the liquid crystalline polyester and the liquid crystalline polyester amide include aromatic diols such as aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid (HBA) and 6-hydroxy-2-naphthoic acid (HNA), 2, 6-dihydroxynaphthalene, 1, 4-dihydroxynaphthalene, 4' -dihydroxybiphenyl, hydroquinone, resorcinol, a compound represented by the following general formula (I), and a compound represented by the following general formula (II); aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 4' -diphenyldicarboxylic acid, 2, 6-naphthalenedicarboxylic acid, and compounds represented by the following general formula (III); aromatic amines such as p-aminophenol and p-phenylenediamine.

(X: is selected from the group consisting of alkylene (C)₁～C₄) Alkylidene, O-, -SO-, -SO₂-、S-and-CO-. )

(Y is selected from the group consisting of- (CH)₂)_n- (n-1-4) and-O (CH)₂)_nAnd (1-4) O- (n). )

The method for producing the liquid crystalline polyester and the liquid crystalline polyester amide is not particularly limited, and the liquid crystalline polyester amide can be produced by a known method using the above-mentioned monomer compound (or a mixture of monomers), and usually a melt polymerization method, a solution polymerization method, a slurry polymerization method, a solid phase polymerization method, or the like, or a combination of 2 or more of these methods, and preferably a melt polymerization method or a combination of a melt polymerization method and a solid phase polymerization method. In the case of a compound having an ester-forming ability, it may be used in the polymerization in its original form, or it may be modified from a precursor to a derivative having the ester-forming ability by using an acylating agent or the like in the previous stage of the polymerization. Examples of the acylating agent include carboxylic anhydrides such as acetic anhydride.

In the polymerization, various catalysts can be used. Typical examples of the catalyst to be used include metal salt catalysts such as potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, antimony trioxide and cobalt (III) tris (2, 4-pentanedionate), and organic compound catalysts such as N-methylimidazole and 4-dimethylaminopyridine. The amount of the catalyst used is usually about 0.001 to 1% by mass, particularly preferably about 0.01 to 0.2% by mass, based on the total weight of the monomers.

In the production stage, various fibrous, powdery, plate-like, inorganic fillers and/or organic fillers may be blended in the liquid crystalline resin a. Examples of the fibrous filler include inorganic fibrous materials such as glass fibers, milled glass fibers, carbon fibers, asbestos fibers, silica-alumina fibers, zirconia fibers, boron nitride fibers, silicon nitride fibers, boron fibers, potassium titanate fibers, and wollastonite and other silicate fibers, magnesium sulfate fibers, aluminum borate fibers, and metallic fibrous materials such as stainless steel, aluminum, titanium, copper, and brass. A typical fibrous filler is glass fiber. High-melting organic fibrous materials such as polyamide, fluororesin, polyester resin, and acrylic resin may also be used.

Examples of the particulate filler include carbon black, graphite, silica, quartz powder, glass beads, glass spheres, glass powder, silicates such as calcium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, and wollastonite, oxides of metals such as iron, titanium, zinc, antimony trioxide, and aluminum, carbonates of metals such as calcium carbonate and magnesium carbonate, sulfates of metals such as calcium sulfate and barium sulfate, other ferrites, silicon carbide, silicon nitride, boron nitride, and various metal powders.

The plate-like filler includes mica, glass flake, talc, various metal foils, and the like.

These inorganic fillers and/or organic fillers may be used singly or in combination of two or more.

The content of the filler may be 0to 100 parts by mass with respect to 100 parts by mass of the liquid crystalline resin a.

The liquid crystalline resin a may further contain additives such as an antioxidant, a heat stabilizer, an ultraviolet absorber, a lubricant, a pigment, and a crystal nucleating agent as other components.

The melting point of the liquid crystalline resin a is 250 ℃ to 370 ℃, preferably 260 ℃ to 360 ℃, and more preferably 280 ℃ to 355 ℃. "melting point" means the melting point Tm2 as determined by differential scanning calorimetry. The melting point is 250 ℃ or higher and 370 ℃ or lower, and therefore the heat resistance of the liquid crystalline resin fine particles can be improved. The melting point Tm2 is set to the following temperature: after measuring the temperature of the peak top of the endothermic peak (melting point Tm1) observed when heating from room temperature (round 1) at a temperature rise rate of 20 ℃/min by the method based on JIS K-7121(1999), the temperature of the peak top of the endothermic peak of round 2 observed when heating from room temperature (round 2) at a temperature rise rate of 20 ℃/min was maintained at (melting point Tm1+40) ° C for 2 minutes, followed by cooling to room temperature at a temperature fall rate of 20 ℃/min and heating again from room temperature at a temperature rise rate of 20 ℃/min.

The melt viscosity of the liquid crystalline resin a is not particularly limited, and can be adjusted according to the application. For example, the cylinder temperature and shear rate are higher by 10to 30 ℃ than the melting point Tm2 measured by a differential scanning calorimeter, and 1000sec^-1The measured melt viscosity may be 1Pa · s or more and 300Pa · s or less, and may be 5Pa · s or more and 100Pa · s or less. The melt viscosity measured at a "cylinder temperature 10to 30 ℃ higher than the melting point Tm 2" means a melt viscosity measured at any temperature appropriately selected depending on the kind of liquid crystalline resin at a cylinder temperature 10to 30 ℃ higher than the melting point Tm2, and the melt viscosity measured at a temperature 10to 30 ℃ higher than the melting point Tm2 may not be all within the above range. The melt viscosity can be adjusted by adjusting the final polymerization temperature at the time of melt polymerization of the liquid crystalline resin.

(thermoplastic resin B)

The thermoplastic resin B is soluble in a solvent described later, and the content of ester bonds and amide bonds in the thermoplastic resin incompatible with the liquid crystalline resin a is 20 mol% or less in total of all monomer units. The term "incompatible property" as used herein means that when the liquid crystalline resin a and the thermoplastic resin B are mixed, the liquid crystalline resin a is dispersed in island-like form in the matrix resin formed of the thermoplastic resin B. The content of ester bonds and amide bonds in the thermoplastic resin B is preferably 10 mol% or less, more preferably 5 mol% or less, based on the total monomer units. The thermoplastic resin B is more preferably a thermoplastic resin having no ester bond or amide bond in its chemical structure.

In one embodiment, the thermoplastic resin B is preferably a thermoplastic resin that is soluble in a solvent described later and is incompatible with the liquid crystalline resin a, and the content of hydroxyl groups, carboxyl groups, amino groups, ester bonds, and amide bonds in the total monomer units is 20 mol% or less, more preferably 10 mol% or less, and still more preferably 5 mol% or less. In addition, as the thermoplastic resin B, a thermoplastic resin having no hydroxyl group, carboxyl group, and amino group, an ester bond, and an amide bond may be used.

Since the content of ester bonds and amide bonds in the thermoplastic resin B is 20 mol% or less in total of all monomer units, the transesterification reaction or the amide exchange reaction between the liquid crystalline resins a can be prevented even when melt-mixing is performed at a temperature exceeding 280 ℃. As a result, the liquid crystalline resin fine particles finally obtained can be prevented from being contaminated with impurities, and the generation of gas during melt mixing can be prevented. Since impurities in the liquid crystalline resin fine particles can be prevented, liquid crystalline resin fine particles having higher rigidity and excellent high elasticity, heat resistance, impact resistance, chemical resistance and the like can be obtained. In addition, by using the thermoplastic resin B as a matrix resin, spherical liquid crystalline resin fine particles can be easily obtained as shown in examples described later. Since spherical liquid crystalline resin fine particles can be easily obtained, a powder material having excellent powder flowability can be obtained at a lower cost. The contents of hydroxyl groups, carboxyl groups, amino groups, ester bonds and amide bonds in the thermoplastic resin B can be determined by FT-IR,¹H-NMR、¹³C-NMR measurement, etc.

The terminal functional group of the thermoplastic resin B is preferably selected from a hydrogen atom, a halogen atom, an alkyl group having 1 or more and 10 or less carbon atoms which may have a substituent, an aryl group having 6 or more and 12 or less carbon atoms which may have a substituent, and an alkoxy group having 1 or more and 10 or less carbon atoms which may have a substituent; at least one of an aryloxy group having 6 to 12 carbon atoms and a vinyl group, which may have a substituent.

In one embodiment, the terminal functional group of the thermoplastic resin B is preferably at least one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms and optionally having a substituent other than a hydroxyl group, a carboxyl group and an amino group, an aryl group having 6 to 12 carbon atoms and optionally having a substituent other than a hydroxyl group, a carboxyl group and an amino group, an alkoxy group having 1 to 10 carbon atoms and optionally having a substituent other than a hydroxyl group, a carboxyl group and an amino group, an aryloxy group having 6 to 12 carbon atoms and optionally having a substituent other than a hydroxyl group, a carboxyl group and an amino group, and a vinyl group.

Among them, the terminal functional group of the thermoplastic resin B is more preferably a methyl group from the viewpoint of suppressing transesterification. The "terminal functional group" may be used¹H-NMR、¹³C-NMR measurement, etc.

The repeating units in the chemical structure of the thermoplastic resin B are preferably bonded by any one selected from the group consisting of an ether bond, an alkylene bond, an imide bond, a urethane bond, a sulfide bond, and a sulfone bond. The bonding state of the repeating unit of the chemical structure of the thermoplastic resin B can be measured by FT-IR or the like.

Examples of such a thermoplastic resin B include polystyrene resin, olefin resin, cycloolefin resin, derivatives thereof, and copolymers of these components with each other or with other components.

Examples of the olefin resin include polyethylene, polypropylene, polybutene, and poly-4-methyl-1-pentene. Examples of the polyethylene include high-pressure polyethylene (LDPE), linear high-density polyethylene (HDPE), medium-density polyethylene (MDPE), linear low-density polyethylene (LLDPE), and very low-density polyethylene (VLDPE, ULDPE).

Examples of the cycloolefin resin include cycloolefin polymers and cycloolefin copolymers.

Examples of the derivative include derivatives having a functional group (preferably a functional group other than a hydroxyl group, a carboxyl group, and an amino group) introduced thereinto, and examples thereof include modified polystyrene resins, modified olefin resins, and modified cyclic olefin resins having maleic anhydride as a substituent.

Examples of the copolymer include an ethylene-styrene copolymer.

As the thermoplastic resin B, 1 or 2 or more thermoplastic resins selected from these can be used. Among them, at least one selected from the group consisting of polystyrene and derivatives thereof is preferable from the viewpoint of easy solubility in solvents and cost.

The melting point (crystalline resin) or glass transition point (amorphous resin) of the thermoplastic resin B is 80 ℃ or higher and 400 ℃ or lower, preferably 80 ℃ or higher and 350 ℃ or lower, and more preferably 100 ℃ or higher and 300 ℃ or lower. The melting point or glass transition point is 80 ℃ or higher and 400 ℃ or lower, and therefore, the melt-kneading can be carried out with a liquid crystalline resin having a high melting point. The "melting point" refers to a melting point Tm2 measured by a differential scanning calorimeter in the same manner as described above. Melting point Tm2 is as described above. In addition, the "glass transition point" (glass transition temperature) means a glass transition point Tg measured by a differential scanning calorimeter.

From the viewpoint of improving the dispersibility of the liquid crystalline resin A, the melt viscosity of the thermoplastic resin B was 1000sec at a cylinder temperature and a shear rate 15 ℃ higher than the melting point Tm2 of the liquid crystalline resin A^-1The measured melt viscosity is preferably 0.1 to 10 times, more preferably 0.5 to 5 times, and still more preferably 0.8 to 3 times the melt viscosity of the liquid crystalline resin a.

(melt mixing)

In the melt-mixing step, the liquid crystalline resin a and the thermoplastic resin B are melt-mixed at a cylinder temperature of 280 ℃ to 400 ℃, preferably 300 ℃ to 390 ℃, and more preferably 320 ℃ to 380 ℃ to obtain a composition C. By melt-mixing at 280 ℃ to 400 ℃, the liquid crystalline resin a can be mixed with good dispersibility in the thermoplastic resin B as a matrix resin. The melt-mixing method is not particularly limited, and may be carried out using a known melt-kneading machine such as a single-screw or twin-screw extruder. When the extrusion step described later is included, a melt-kneading machine with a nozzle is preferably used. In the melt-kneading, the respective components may be uniformly mixed in advance by using a device such as a tumble mixer or a henschel mixer, or the respective components may be quantitatively supplied to the melt-kneading device without mixing in advance.

The mixing ratio of the liquid crystalline resin a and the thermoplastic resin B is 300 parts by mass or more and 900 parts by mass or less, preferably 3 parts by mass or more and 40 parts by mass or less, and more preferably 5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the liquid crystalline resin a. By setting the mixing ratio as described above, the liquid crystalline resin a can be mixed with good dispersibility in the thermoplastic resin B as the matrix resin, and spherical liquid crystalline resin fine particles can be obtained in a cleaning step described later.

(composition C)

The composition C is a composition in which a particulate liquid crystalline resin a is dispersed in a thermoplastic resin B as a matrix resin. The shape of the composition C is not particularly limited, and may be in the form of pellets when an extrusion step described later is performed after the melt-mixing step, or in the form of blocks when no extrusion step is performed.

[ extrusion Process ]

The method for producing liquid crystalline resin fine particles according to the present embodiment may have, as required, the following extrusion step after the melt-mixing step and before the washing step: strands of composition C were formed using a nozzle-equipped extruder, followed by cutting to obtain pellets.

Product nS (mm) of the number n of nozzle openings of an extruder and the area S of each opening²) The ratio (nS/Q) to the resin extrusion amount Q (kg/hr) per 1 hour is preferably 20 or more and 80 or less, more preferably 25 or more and 60 or less, and still more preferably 30 or more and 50 or less. When the value of nS/Q is within the above range, the liquid crystalline resin a in the composition C can be prevented from being stretched and deformed when extruded from the extruder, and the ratio of spherical fine particles in the finally obtained liquid crystalline resin fine particles can be further increased.

[ cleaning Process ]

The washing step is a step of stirring the composition C obtained in the melt-mixing step or the composition C in the form of pellets after the extrusion step in a solvent that does not dissolve the liquid crystalline resin a and dissolves the thermoplastic resin B.

(solvent)

As the solvent which does not dissolve the liquid crystal resin a and dissolves the thermoplastic resin B, a solvent in which the solubility of the liquid crystal resin a is 1 or less and the solubility of the thermoplastic resin B is 5 or more, the solubilities being expressed by the mass (g) of the resin dissolved in 100g of the solvent at 40 ℃. By stirring the composition C in the solvent, the thermoplastic resin can be removed from the composition C to obtain liquid crystalline resin fine particles mainly containing the liquid crystalline resin a.

Examples of the solvent include organic solvents such as nitrobenzene, phenol, toluene, methylene chloride, carbon tetrachloride, methyl ethyl ketone, acetone, dimethylformamide, dimethyl sulfoxide, dimethyl sulfone, tetramethyl sulfone, and tetramethylene sulfoxide, and 1 or 2 or more kinds of organic solvents selected from these can be used. When polystyrene is used as the thermoplastic resin B, toluene is preferably used.

The stirring time and the stirring temperature are not particularly limited, and may be, for example, 30 to 100 ℃ for 40 to 80 minutes by using an electromagnetic stirrer or the like. Then, the solution is filtered using a filter or the like to recover insoluble components, and the insoluble components are further dried as necessary to obtain liquid crystalline resin fine particles.

(liquid Crystal resin Fine particles)

The liquid crystalline resin fine particles (powdery liquid crystalline resin) mainly contain a liquid crystalline resin and are substantially spherical. The term "mainly contains" means that the content of the liquid crystalline resin a in the liquid crystalline resin fine particles is 50% by mass or more, preferably 0% by mass or more, and more preferably 80% by mass or more. The content of other resin components as impurities other than the liquid crystalline resin a in the liquid crystalline resin fine particles is preferably 0.1 mass% or less, more preferably 0.05 mass% or less, and still more preferably 0.01 mass% or less. By setting the content to this range, fine resin particles containing little or substantially no other resin component as impurities can be produced, and a powder material having various excellent characteristics such as heat resistance, impact resistance, and chemical resistance of the liquid crystalline resin a can be produced. The "other resin component as impurities" includes a thermoplastic resin B as a matrix resin, a resin component obtained by subjecting a liquid crystalline resin a and the thermoplastic resin B to an ester exchange reaction or an amide exchange reaction, and the like. The content of the impurities can be determined by extracting the impurities from the liquid crystalline resin fine particles using a solvent capable of dissolving the impurities and utilizing¹H-NMR measurement. Further, when the 1% weight loss temperature measured by the differential thermal gravimetric simultaneous measurement apparatus is not less than (melting point Tm2+150) ° c, it can be judged that the impurities are small.

The term "fine particles" means particles having an average particle diameter of about 0.1 to 1000. mu.m. The average particle diameter of the liquid crystalline resin fine particles is preferably 1 μm or more and 150 μm or less, more preferably 1 μm or more and 100 μm or less, further preferably 5 μm or more and 80 μm or less, and particularly preferably 10 μm or more and 50 μm or less. The production method of the present embodiment can provide spherical liquid crystalline resin fine particles having an average particle diameter of 1 μm or more and 150 μm or less (for example, 1 μm or more and 100 μm or less), and can be suitably used for various applications such as coating materials, powder materials for molded articles, and additives. The "average particle diameter" refers to an arithmetic average particle diameter on a volume basis based on a laser diffraction/scattering type particle size distribution measurement method. The average particle diameter can be measured, for example, using a laser diffraction/scattering particle size distribution measuring device LA-920 manufactured by horiba, Ltd.

The melting point Tm2 of the liquid crystalline resin fine particles is preferably 250 ℃ to 370 ℃ inclusive, more preferably 260 ℃ to 360 ℃ inclusive, and further preferably 280 ℃ to 355 ℃ inclusive, as is the same as the melting point Tm2 of the liquid crystalline resin a. When the melting point Tm2 is within the above range, liquid crystal resin fine particles having high heat resistance can be obtained. "melting point Tm 2" is as described above.

The melt viscosity of the liquid crystalline resin fine particles can be adjusted depending on the application, and for example, the cylinder temperature and the shear rate are 10to 30 ℃ higher than the melting point Tm2 measured by a differential scanning calorimeter and 100sec is the shear rate^-1The measured melt viscosity may be 1Pa · s or more and 300Pa · s or less, and may be 5Pa · s or more and 100Pa · s or less. When the melt viscosity is within the above range, moldability can be improved when the composition is used as a powder material for a molded article, for example.

Examples

The present invention will be further specifically described with reference to the following examples, but the present invention is not to be construed as being limited thereto.

The liquid crystalline resins used in examples and comparative examples were produced in the following manner.

Production example 1 LCP 1: wholly aromatic polyester

After charging the following raw materials into a polymerization vessel, the temperature of the reaction system was raised to 140 ℃ and the reaction was carried out at 140 ℃ for 1 hour. Then, the temperature was raised to 330 ℃ over a further 3.5 hours, and then the pressure was reduced to 10Torr (1330 Pa) over a further 15 minutes, and polycondensation was carried out while distilling off acetic acid, excess acetic anhydride, and other low-boiling components. After the stirring torque reached a predetermined value, nitrogen gas was introduced, the pressure was increased from a reduced pressure state to a normal pressure state, and the polymer was discharged from the lower part of the polymerization vessel, and the strand was pelletized to obtain LCP1 pellets. The melting point Tm2 of the obtained LCP1 was 325 ℃ and the melt viscosity was 31 pas. The melting point Tm2 and the melt viscosity of LCP1 were measured by the methods described later.

(raw materials)

4-hydroxybenzoic acid; 2524g (79.3 mol%)

6-hydroxy-2-naphthoic acid; 867g (20 mol%)

Terephthalic Acid (TA); 27g (0.3 mol%)

Metal catalysts (potassium acetate catalysts); 150mg of

An acylating agent (acetic anhydride); 2336g

Production example 2 LCP 2: wholly aromatic polyester

After charging the following raw materials into a polymerization vessel, the temperature of the reaction system was raised to 140 ℃ and the reaction was carried out at 140 ℃ for 1 hour. Then, the temperature was raised to 360 ℃ over a further 5.5 hours, and then the pressure was reduced to 5Torr (667 Pa) over a further 30 minutes, and melt polymerization was carried out while distilling off acetic acid, excess acetic anhydride, and other low boiling components. After the stirring torque reached a predetermined value, nitrogen was introduced, the pressure was increased from a reduced pressure state to a normal pressure state, and the polymer was discharged from the lower part of the polymerization vessel, and the strand was pelletized to obtain pellets. The obtained pellets were heated from room temperature to 290 ℃ for 20 minutes under a nitrogen atmosphere, and after holding for 3 hours, they were allowed to cool to obtain pellets of LCP 2. The melting point Tm2 of the obtained pellets of LCP2 was 348 ℃ and the melt viscosity was 55 pas. The melting point Tm2 and the melt viscosity of LCP2 were measured by the methods described later.

(raw materials)

4-hydroxybenzoic acid; 37g (2 mol%)

6-hydroxy-2-naphthoic acid; 1218g (48 mol%)

Terephthalic acid; 560g (25 mol%)

4, 4' -dihydroxybiphenyl; 628g (25 mol%)

Metal catalysts (potassium acetate catalysts); 165mg

An acylating agent (acetic anhydride); 1432g

[ measurement of physical Properties ]

(melting Point Tm2)

The melting point Tm2 of the liquid crystalline resin was measured using a differential scanning calorimeter (manufactured by Hitachi High-Tech Science Corporation, DSC7000X) at the following peak top temperatures: after the temperature of the peak top of the endothermic peak (melting point Tm1) observed when heating was performed from room temperature (round 1) at a temperature rising rate of 20 ℃/min, the temperature was maintained at (melting point Tm1+40) ° c for 2 minutes, followed by cooling to room temperature at a temperature falling rate of 20 ℃/min, and the peak top temperature of the endothermic peak of round 2 observed when heating was performed again from room temperature at a temperature rising rate of 20 ℃/min.

(melt viscosity)

The apparent melt viscosity of the liquid crystalline resin was measured according to ISO 11443 using a capillary rheometer (Capillograph 1D: piston diameter 10mm, manufactured by Toyo Seiki Seisaku-Sho Ltd.) under the following conditions. For the measurement, an orifice having an inner diameter of 1mm and a length of 20mm was used.

Barrel temperature:

340℃(LCP1)

370℃(LCP2)

shearing speed: 1000sec^-1

(solubility)

0.1g of LCP1 was added to 100g of toluene kept at 40 ℃ while stirring with an electromagnetic stirrer, and after mixing, LCP1 was precipitated without dissolving. From the results, it was judged that the solubility of LCP1 in toluene was less than 0.1. Similarly, 0.1g of LCP2 was added and mixed, and the mixture was not dissolved but precipitated. Therefore, the solubility of LCP2 in toluene was also judged to be insufficient at 0.1.

Further, with respect to polystyrene 1,2, polyethylene terephthalate, polyethylene oxide and polycarbonate which are thermoplastic resins used in examples and comparative examples described later, 0.1g of each of them was added to toluene and mixed in the same manner as described above, and as a result, no thermoplastic resin was precipitated even at the stage of adding 20g of each of them. From the results, the solubility of the thermoplastic resin in toluene was judged to be 20 or more.

[ example 1]

Polystyrene 1 (manufactured by PS Japan, Inc. 'SGP 10', glass transition temperature Tg100 ℃ C., and melt viscosity 27 pas (cylinder temperature 340 ℃ C., shear rate 1000 sec.) as a thermoplastic resin was added to 100 parts by mass of LCP1 obtained in production example 1^-1) 900 parts by mass, using a twin-screw extruder "TEX-alpha" (the product of the number of nozzle openings and the area of each opening is 300 mm) made by Nippon Steel Co., Ltd²) The resulting mixture was melt-kneaded at a cylinder temperature of 340 ℃ and a screw rotation speed of 125rpm to obtain a composition. The composition was extruded from a circular nozzle at a resin extrusion rate of 10kg/hr to give an extruded strand, which was cut into pellets. At this time, the product nS (mm) of the number n of nozzle openings and the area S of each opening²) The ratio (nS/Q) to the resin extrusion amount Q (kg/hr) per 1 hour was 30.

In a 2L flask, 900g of toluene heated to 40 ℃ was charged, 100g of the obtained composition pellets were stirred for 30 minutes to dissolve polystyrene in toluene. The insoluble matter was recovered by suction filtration, and the residue was further washed with 90g of toluene at 40 ℃. Additional washing was performed 3 times. The insoluble matter after additional washing was collected by filtration with a1 μm filter and dried to obtain fine particles. The fine particles were observed with an electron microscope (ultra-deep multi-angle microscope, KEYENCE, "VHX-D510", 500-fold magnification), and spherical particles were observed. The content of ester bonds and amide bonds in polystyrene 1 was 0 mol% in total of all monomer units.

[ example 2]

Except that polystyrene 2 (manufactured by PS Japan, Inc. 'HF 77', glass transition point Tg100 ℃ C.) as a thermoplastic resin was used as the thermoplastic resin, and the melt viscosity was 16 pas (cylinder temperature 340 ℃ C., shear rate 1000 sec.)^-1) Fine particles were obtained in the same manner as in example 1. As a result of observation with an electron microscope in the same manner as in example 1, spherical particles were observed. An electron micrograph is shown in FIG. 1. In addition, the polyphenylene isThe content of ester bonds and amide bonds in ethylene 2 was 0 mol% in total of all monomer units.

[ example 3]

Microparticles were obtained in the same manner as in example 1, except that the amount of polystyrene 1 used was 300 parts by mass per 100 parts by mass of LCP. As a result of observation with an electron microscope in the same manner as in example 1, spherical particles were observed.

[ example 4]

Polystyrene 2 (manufactured by PS Japan, Inc. 'SGP 10', glass transition point Tg100 ℃ C., melt viscosity 8 pas (cylinder temperature 363 ℃ C., shear rate 1000 sec) as a thermoplastic resin was added to 100 parts by mass of the LCP2 obtained in production example 2^-1) For 900 parts by mass, a twin-screw extruder "TEX-alpha" (product of the number of nozzle openings and the area of each opening: 300 mm), manufactured by Nippon Steel Co., Ltd., was used²) Microparticles were obtained in the same manner as in example 1, except that the composition was obtained by melt-kneading at a cylinder temperature of 363 ℃ and a screw rotation speed of 125 rpm. As a result of observation with an electron microscope in the same manner as in example 1, spherical particles were observed.

Comparative example 1

Except that polyethylene terephthalate (manufactured by INDOLAMA, "BF 3067", melting point (Tm2)254 ℃ C., melt viscosity 28 pas (cylinder temperature 340 ℃ C., shear rate 1000 sec.) was used^-1) Fine particles were obtained in the same manner as in example 1, except that the thermoplastic resin was used. The fine particles were observed in the same manner as in example 1, and spherical particles were observed. The content of ester bonds and amide bonds in the polyethylene terephthalate is 100 mol% in total of all monomer units.

Comparative example 2

Except that polyethylene oxide (available from Ming chemical industries, Ltd., "ALCOX R-150", melting point 65 ℃ C., melt viscosity 1 pas (cylinder temperature 340 ℃ C., shear rate 1000 sec.) was used^-1) Fine particles were obtained in the same manner as in example 1, except that the thermoplastic resin was used. The fine particles were observed in the same manner as in example 1, and spherical particles were observed. It is noted that the polycyclic ringThe content of ester bonds and amide bonds in the ethylene oxide was 0 mol% in total of the monomer units.

Comparative example 3

Except that polycarbonate (manufactured by Diko K.K. 'PANLIGHT L-1225L', glass transition point 148 ℃ C., melt viscosity 63 pas (cylinder temperature 340 ℃ C., shear rate 1000 sec.) was used^-1) Fine particles were obtained in the same manner as in example 1, except that the thermoplastic resin was used. The fine particles were observed in the same manner as in example 1, and spherical particles were observed. The content of ester bonds and amide bonds in the polycarbonate is 100 mol% in total of all monomer units.

[ evaluation ]

The fine particles obtained in examples and comparative examples were evaluated for average particle size, melt viscosity, and 1% weight loss temperature by the following methods. The results are shown in Table 1.

(average particle diameter)

The average particle diameter was measured using a laser diffraction/scattering particle size distribution measuring apparatus (LA-920, manufactured by horiba, Ltd.). The average particle size is an arithmetic average particle size on a volume basis.

(melting Point Tm2)

(melt viscosity)

The apparent melt viscosity of the resin fine particles was measured according to ISO 11443 using a capillary rheometer (Capillograph 1D, manufactured by Toyo Seiki Seisaku-Sho Ltd.: piston diameter 10 mm). For the measurement, an orifice having an inner diameter of 1mm and a length of 20mm was used.

Barrel temperature:

340℃(LCP1)

370℃(LCP2)

shearing speed: 100sec^-1

(1% weight loss temperature)

The measurement was performed using a differential thermogravimetry simultaneous measurement apparatus (TG/DTA, manufactured by Seiko Instruments Inc.) with a 1% weight reduction temperature under a nitrogen gas flow as an index of the content of impurities. The results are shown in Table 1. When the 1% weight loss temperature is not less than (the melting point Tm2+160 of the fine resin particles) ° c, it is judged that the amount of impurities is small.

As shown in Table 1, the fine resin particles obtained in the examples were spherical, and had a 1% weight loss temperature of not less than (melting point Tm2+160 of the fine resin particles) and few impurities. On the other hand, as shown in Table 2, the fine resin particles obtained in the comparative example were spherical, but the 1% weight loss temperature was insufficient (melting point Tm2+160 of the fine resin particles) DEG C, and impurities were large.

[ Table 1]

[ Table 2]

Claims

1. A method for producing liquid crystalline resin fine particles, comprising the steps of:

a melt-mixing step of melt-mixing 100 parts by mass of a liquid crystalline resin A having a melting point of 250 to 370 ℃ and 300 to 900 parts by mass of a thermoplastic resin B, which is incompatible with the liquid crystalline resin A and has a melting point or glass transition point of 80 to 400 ℃, at 280 to 400 ℃ to obtain a composition C; and

a cleaning step of stirring the composition C in a solvent in which the solubility of the liquid crystalline resin A is 1 or less and the solubility of the thermoplastic resin B is 5 or more, the solubility being represented by the mass (g) of the resin dissolved in 100g of the solvent at 40 ℃,

the content of ester bonds and amide bonds in the thermoplastic resin B used in the melt-mixing step is 5 mol% or less in total of all monomer units,

the liquid crystalline resin A is a liquid crystalline polyester,

the thermoplastic resin B is at least one selected from polystyrene and derivatives thereof, and the solvent is toluene.

2. The production method according to claim 1, wherein an extrusion step of forming strands of the composition C using a nozzle-equipped extruder and obtaining pellets is provided after the melt-mixing step and before the washing step,

the product nS (mm) of the number n of nozzle openings and the area S of each opening of the extruder²) The ratio (nS/Q) of the amount of extrusion of the resin per 1 hour to the amount of extrusion of the resin Q (kg/hr) is 20 to 80 inclusive.

3. The production method according to claim 1 or 2, wherein the terminal functional group of the thermoplastic resin B is at least one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 or more and 10 or less carbon atoms which may be substituted, an aryl group having 6 or more and 12 or less carbon atoms which may be substituted, an alkoxy group having 1 or more and 10 or less carbon atoms which may be substituted, an aryloxy group having 6 or more and 12 or less carbon atoms which may be substituted, and a vinyl group.

4. The production method according to claim 1 or 2, wherein the repeating unit of the chemical structure of the thermoplastic resin B is bonded by any one selected from an ether bond, an alkylene bond, an imide bond, a urethane bond, a sulfide bond, and a sulfone bond.

5. The production method according to claim 1 or 2, wherein the liquid crystalline resin fine particles have an average particle diameter of 1 μm or more and 150 μm or less.

6. The production method according to claim 1 or 2, wherein the thermoplastic resin B used in the melt-mixing step does not contain an ester bond in its chemical structure.