Method for manufacturing liquid crystal polymer microparticles

Abstract

To provide a method for producing liquid crystal polymer particulates with a smooth surface texture, which are spherical and small in particle size.SOLUTION: A method for producing liquid crystal polymer particulates with an average particle size of 0.01-100 μm includes the steps of: mixing a resin composition, including 100 pts.mass of a polyamide resin and 0.1-150 pts.mass of a liquid crystal polymer, with a solvent, dissolving the polyamide resin included in the resin composition, to obtain the liquid crystal polymer particulate dispersion in the polyamide resin solution; and removing the polyamide resin solution from the dispersion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing liquid crystal polymer fine particles. [Background Art]

[0002] Resin fine particles and powders are used in various applications such as powder materials for coating, powder materials for molded article production, and additives. Liquid crystal polymers have high rigidity and high elasticity, and are excellent in heat resistance, impact resistance, chemical resistance, gas barrier property and the like. Therefore, the fine particles and powders thereof 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.

[0003] Liquid crystal polymer particles are generally produced by pulverizing a solid liquid crystal polymer. For example, Patent Document 1 proposes a micropowder obtained by pulverizing a liquid crystal polyester having a flow initiation temperature of 200°C or higher and 270°C or lower, and having an average particle diameter of 0.5 to 50 µm. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2003-268121 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, since liquid crystal polymers have the characteristic that molecules are highly oriented along the long axis direction, when mechanically pulverized with a pulverizer, the liquid crystal polymer tends to become fibril-shaped or fibrous, and spherical particles cannot be obtained.

[0006] An object of the present invention is to provide a method for producing liquid crystal polymer fine particles that have a smooth surface, are spherical, and have a small particle size. Another object of the present invention is to provide a method for producing liquid crystal polymer fine particles with improved productivity. [Means for solving the problem]

[0007] In view of the above problems, the present inventors conducted diligent studies and found that by dissolving the polyamide resin in a resin composition containing 100 parts by mass of polyamide resin and 0.1 to 150 parts by mass of liquid crystal polymer with a polyamide resin-soluble solvent, it is possible to efficiently obtain spherical liquid crystal polymer fine particles with small particle sizes, thus completing the present invention.

[0008] In other words, the present invention encompasses the following preferred embodiments. [1] A step of mixing a resin composition containing 100 parts by mass of polyamide resin and 0.1 to 150 parts by mass of liquid crystal polymer with a solvent to dissolve the polyamide resin contained in the resin composition, in order to obtain a dispersion of liquid crystal polymer fine particles in a polyamide resin solution, and A step of removing the polyamide resin solution from the dispersion, A method for producing liquid crystal polymer fine particles having an average particle size of 0.01 to 100 μm, including [the specified element]. [2] The method according to [1], wherein the polyamide resin comprises one or more selected from the group consisting of polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 6T, polyamide 6I, polyamide 9T, polyamide 46, polyamide MXD6, and polymerized fatty acid polyamide. [3] Liquid crystal polymers are derived from formulas [I] and [II] [ka] The method according to [1] or [2], wherein the polymer is a fully aromatic liquid crystal polymer containing repeating units represented by . [4] Liquid crystal polymers are given by formulas [I] to [IV] [ka] [In the formula, Ar1 and Ar2 each represent one or more divalent aromatic groups, and p, q, r, and s are the composition ratios (mol%) of each repeating unit in the liquid crystal polymer, satisfying the following conditions: 0.5 ≤ p / q, 5≦r≦35, and [5≦s≦35] The method according to any one of [1] to [3], wherein the fully aromatic liquid crystal polymer contains repeating units represented by . [5] Equations [III] and / or [IV] show that Ar1 and Ar2 are independent of each other, as shown in equations (1) to (4) [ka] The method according to [4], which is a fully aromatic liquid crystal polymer comprising one or more repeating units that are aromatic groups selected from the group consisting of the above. [6] The method according to any one of [1] to [5], wherein the crystal melting temperature of the liquid crystal polymer is 170 to 250°C. [7] The method according to any one of [1] to [6], wherein the resin composition is a molten kneaded product containing a polyamide resin and a liquid crystal polymer. [8] The method according to any one of [1] to [7], wherein the solvent comprises one or more selected from the group consisting of p-cresol, o-cresol, m-cresol, phenol, water, methanol, ethanol, n-propanol, isopropanol, toluene, xylene, cyclohexane, methylcyclohexane, and methyl ethyl ketone. [9] The method according to any one of [1] to [8], wherein the amount of solvent to be mixed with the resin composition is 100 to 5000 parts by mass per 100 parts by mass of polyamide resin.

[10] Liquid crystal polymer fine particles having an average particle diameter of 0.01 to 100 μm and an average sphericity of 1.8 or less.

[11] A dispersion of liquid crystal polymer microparticles, wherein liquid crystal polymer microparticles having an average particle diameter of 0.01 to 100 μm and an average sphericity of 1.8 or less are dispersed in a solvent.

[12] A liquid crystal polymer fine particle dispersion comprising 100 parts by mass of a polyamide resin and 0.1 to 150 parts by mass of a liquid crystal polymer, wherein the polyamide resin is dissolved in a solvent, and liquid crystal polymer fine particles having an average particle diameter of 0.01 to 100 µm and an average sphericity of 1.8 or less are dispersed in the polyamide resin solution.

[13] The dispersion according to

[11] or

[12] , wherein the solvent comprises one or more selected from the group consisting of p-cresol, o-cresol, m-cresol, phenol, water, methanol, ethanol, n-propanol, isopropanol, toluene, xylene, cyclohexane, methylcyclohexane, and methyl ethyl ketone. Effects of the Invention

[0009] According to the present invention, spherical liquid crystal polymer fine particles having a small particle diameter can be efficiently obtained. Brief Description of the Drawings

[0010] [Figure 1] It is a scanning electron microscope (SEM) photograph of the liquid crystal polymer fine particles obtained in Example 1. [Figure 2] It is a microscope photograph of a ground product of liquid crystal polymer pellets ground in Comparative Example 2. Mode for Carrying Out the Invention

[0011] The resin composition used in the method for producing liquid crystal polymer fine particles of the present invention comprises a polyamide resin and a liquid crystal polymer.

[0012] The polyamide resin used in the present invention is a polymer having amide bonds in its molecule, and examples include polymers obtained by polymerizing α-pyrrolidone, α-piperidone, ε-caprolactam, 6-aminocaproic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, ω-laurolactam, etc.; and polymers obtained by condensation polymerization of diamines such as hexamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, metaxylylenediamine, and 1,4-bis(aminomethyl)cyclohexane with dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid.

[0013] The polyamide resin used in the present invention has an amide bond content of more than 50 mol% of the total monomer units, preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more. If the amide bond content of the molecule is 50 mol% or less of the total monomer units, the resulting fine particles tend to be irregular in shape rather than spherical.

[0014] Specific examples of polyamide resins used in the present invention include polyamide 6 obtained by polymerizing ε-caprolactam, polyamide 66 obtained by condensation polymerization of hexamethylenediamine and adipic acid, polyamide 610 obtained by condensation polymerization of hexamethylenediamine and sebaic acid, polyamide 6T obtained by condensation polymerization of hexamethylenediamine and terephthalic acid, polyamide 6I obtained by condensation polymerization of hexamethylenediamine and isophthalic acid, polyamide 46 obtained by condensation polymerization of diaminobutane and adipic acid, polyamide MXD6 obtained by condensation polymerization of metaxylylenediamine and adipic acid, polyamide 9T obtained by condensation polymerization of nonanediamine and terephthalic acid, polyamide 11 obtained by polymerizing 11-aminoundecanoic acid, and polyamide 12 obtained by polymerizing 12-aminododecanoic acid or ω-laurolactam.

[0015] In addition, ternary (6-66-610) copolymerized polyamides, quaternary (6-66-610-12) copolymerized polyamides, N-alkoxymethylated polyamides, polymerized fatty acid polyamides, polymerized fatty acid polyamide block copolymers, etc., may also be used. A "polymerized fatty acid polyamide" refers to a condensate of polymerized fatty acids (polymers of unsaturated fatty acids) and diamines. Examples of unsaturated fatty acids include linoleic acid, oleic acid, ricinoleic acid, unsaturated fatty acids contained in castor oil, soybean oil, flaxseed oil, etc.

[0016] Of these, polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 6T, polyamide 6I, polyamide 9T, polyamide 46, polyamide MXD6, and polymerized fatty acid polyamides are preferred as polyamide resins used in the present invention. In particular, polyamide 6, polyamide 66, polyamide 46, and polyamide MXD6 are preferred because they undergo little change in physical properties or dimensions due to moisture absorption, and polymerized fatty acid polyamides are preferred because they have high solubility in alcohol. These polyamide resins can be used individually or in mixtures of two or more types.

[0017] The liquid crystal polymer used in this invention is a liquid crystal polyester or liquid crystal polyesteramide that forms an anisotropic molten phase, which is known to those skilled in the art as a thermotropic liquid crystal polymer.

[0018] The properties of the anisotropic molten phase of a liquid crystal polymer can be confirmed using a standard deflection inspection method with orthogonal deflectors, that is, by observing a sample placed on a hot stage under a nitrogen atmosphere.

[0019] Examples of repeating units that constitute the liquid crystal polymer used in the present invention include aromatic oxycarbonyl repeating units, aromatic dicarbonyl repeating units, aromatic dioxy repeating units, aromatic aminooxy repeating units, aromatic diamino repeating units, aromatic aminocarbonyl repeating units, and combinations thereof.

[0020] Specific examples of monomers that give aromatic oxycarbonyl repeating units include, for example, aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 2-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 5-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 4'-hydroxyphenyl-4-benzoic acid, 3'-hydroxyphenyl-4-benzoic acid, 4'-hydroxyphenyl-3-benzoic acid, and alkyl, alkoxy, or halogen-substituted derivatives thereof, as well as ester-forming derivatives such as acylids, ester derivatives, and acid halides thereof. Among these, 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid are preferred because they make it easy to adjust the mechanical properties, heat resistance, crystal melting temperature, and moldability of the resulting liquid crystal polymer to appropriate levels.

[0021] Specific examples of monomers that give aromatic dicarbonyl repeating units include, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and 4,4'-dicarboxybiphenyl, as well as alkyl, alkoxy, or halogen-substituted derivatives thereof, and ester-forming derivatives such as ester derivatives and acid halides thereof. Among these, terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are preferred because they make it easy to adjust the mechanical properties, heat resistance, crystal melting temperature, and moldability of the resulting liquid crystal polymer to appropriate levels.

[0022] Specific examples of monomers that give aromatic dioxy repeating units include, for example, aromatic diols such as hydroquinone, resorcinol, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, and 4,4'-dihydroxybiphenyl ether, as well as alkyl, alkoxy, or halogen-substituted derivatives thereof, and ester-forming derivatives such as acylated derivatives thereof. Among these, hydroquinone and 4,4'-dihydroxybiphenyl are preferred because their reactivity during polymerization, mechanical properties, heat resistance, crystal melting temperature, and moldability of the resulting liquid crystal polymer can be easily adjusted to appropriate levels.

[0023] Monomers that yield aromatic aminooxy repeating units, aromatic diamino repeating units, and aromatic aminocarbonyl repeating units include aromatic hydroxyamines, aromatic diamines, and aromatic aminocarboxylic acids.

[0024] The liquid crystal polymer used in the present invention may contain aromatic oxydicarbonyl repeating units or thioester bonds, to the extent that it does not impair the objectives of the present invention. Examples of monomers that give thioester bonds include mercaptoaromatic carboxylic acids, aromatic dithiols, and hydroxyaromatic thiols. The amount of these monomers used is preferably 10 mol% or less of the total amount including monomers that give aromatic oxycarbonyl repeating units, aromatic dicarbonyl repeating units, aromatic dioxy repeating units, aromatic aminooxy repeating units, aromatic diamino repeating units, and aromatic aminocarbonyl repeating units.

[0025] While some copolymers combining these repeating units may form an anisotropic molten phase and others may not, depending on the monomer composition, composition ratio, and sequence distribution of each repeating unit within the copolymer, the liquid crystal polymers used in this invention are limited to copolymers that form an anisotropic molten phase.

[0026] The liquid crystal polymer used in this invention may be a blend of two or more liquid crystal polymers.

[0027] The crystal melting temperature of the liquid crystal polymer used in the present invention, as measured by a differential scanning calorimeter, is preferably 380°C or lower, more preferably 350°C or lower, even more preferably 150 to 300°C, and particularly preferably 170 to 250°C.

[0028] Because the crystal melting temperature of the liquid crystal polymer is within the above temperature range, the liquid crystal polymer can be easily dispersed uniformly in the polyamide resin, which is suitably present as a matrix in the resin composition to be mixed with the solvent, resulting in liquid crystal polymer fine particles that are small in size and uniform in shape.

[0029] In the present invention, the difference between the crystal melting temperatures of the polyamide resin and the liquid crystal polymer contained in the resin composition is preferably 100°C or less, more preferably 80°C or less, and even more preferably 50°C or less, from the viewpoint of uniform dispersion of the liquid crystal polymer in the resin composition.

[0030] In this specification and in the claims, "crystal melting temperature" refers to the crystal melting peak temperature measured using a Differential Scanning Calorimeter (DSC) at a heating rate of 20°C / min. More specifically, after observing the endothermic peak temperature (Tm1) observed when measuring a liquid crystal polymer sample from room temperature under a heating condition of 20°C / min, the sample is held at a temperature 20 to 50°C higher than Tm1 for 10 minutes, then the sample is cooled to room temperature under a cooling condition of 20°C / min, and the endothermic peak is observed again under a heating condition of 20°C / min. The temperature at which the peak top is shown is defined as the crystal melting temperature of the liquid crystal polymer. For example, an Exstar 6000 manufactured by Seiko Instruments Inc. can be used as the measuring instrument.

[0031] The melt viscosity of the liquid crystal polymer used in this invention (measured with a capillary rheometer, crystal melting temperature + 40°C, 1000 s) -1 The pressure is preferably 1 to 1000 Pa·s, and more preferably 5 to 500 Pa·s.

[0032] When the melt viscosity is less than 1 Pa·s, the liquid crystal polymer tends to disperse less uniformly in the resin composition, and when it exceeds 1000 Pa·s, it also tends to disperse less uniformly.

[0033] As the liquid crystal polymer used in the present invention, a fully aromatic liquid crystal polymer is preferably used, and formulas [I] and [II] [ka] A fully aromatic liquid crystal polymer containing repeating units represented by is more preferably used.

[0034] The liquid crystal polymer used in this invention is from formulas [I] to [IV]. [ka] [In the formula, Ar1 and Ar2 each represent one or more divalent aromatic groups, and p, q, r, and s are the composition ratios (mol%) of each repeating unit in the liquid crystal polymer, satisfying the following conditions: 0.5 ≤ p / q, 5≦r≦35, and [5≦s≦35] A fully aromatic liquid crystal polymer containing repeating units represented by is even more preferably used.

[0035] In one embodiment of the present invention, the molar ratio (p / q) of the composition ratio p (mol%) related to formula [I] and the composition ratio q (mol%) related to formula [II] is more preferably 0.6 to 12, and even more preferably 0.8 to 10.

[0036] For the above-mentioned preferred all-aromatic liquid crystal polymers, the total composition ratio of p and q is preferably 30 to 90 mol%, more preferably 35 to 85 mol%, and even more preferably 40 to 80 mol%.

[0037] For the all-aromatic liquid crystal polymers preferred for use above, the composition ratio p of formula [I] and the composition ratio q of formula [II] are preferably 2 to 60 mol%, and more preferably 5 to 55 mol%, respectively.

[0038] In the all-aromatic liquid crystal polymer suitably used in the present invention, by including repeating units represented by formulas [I] and [II] in at least the above-mentioned molar ratio (p / q), and optionally the sum of the above-mentioned composition ratio of p and q and / or the respective composition ratios (mol%) of p and q, an all-aromatic liquid crystal polymer with appropriately adjusted mechanical properties, heat resistance, and moldability can be suitably obtained.

[0039] In a particularly preferred embodiment of the present invention, the molar ratio (p / q) of the composition ratio p (mol%) related to formula [I] and the composition ratio q (mol%) related to formula [II] is more preferably 0.6 to 1.8, and even more preferably 0.8 to 1.6.

[0040] For the above-mentioned preferred all-aromatic liquid crystal polymers, the total composition ratio of p and q is preferably 50 to 90 mol%, more preferably 60 to 85 mol%, and even more preferably 70 to 82 mol%.

[0041] For the all-aromatic liquid crystal polymers preferred for use above, the composition ratio p of formula [I] and the composition ratio q of formula [II] are preferably 20 to 60 mol%, and more preferably 30 to 55 mol%, respectively.

[0042] In the all-aromatic liquid crystal polymer suitably used in the present invention, by including repeating units represented by formulas [I] and [II] in at least the above-mentioned molar ratio (p / q), and optionally the sum of the above-mentioned composition ratio of p and q and / or the respective composition ratios (mol%) of p and q, an all-aromatic liquid crystal polymer exhibiting the above-mentioned crystal melting temperature can be suitably obtained.

[0043] Furthermore, for the all-aromatic liquid crystal polymer suitably used in the present invention, the composition ratio r in formula [III] and the composition ratio s in formula [IV] are preferably 5 to 35 mol%, more preferably 7 to 33 mol%, and even more preferably 10 to 30 mol%, respectively. It is preferable that r and s are in equimolar amounts.

[0044] In the repeating units described above, for example, Ar1 (or Ar2) represents two or more divalent aromatic groups, which means that two or more repeating units represented by formula [III] (or [IV]) are included in the entire aromatic liquid crystal polymer, depending on the type of divalent aromatic group. In this case, the composition ratio r related to formula [III] (or the composition ratio s related to formula [IV]) represents the total composition ratio of the two or more repeating units.

[0045] Specific examples of monomers that give repeating units represented by formula [I] include, for example, 4-hydroxybenzoic acid and its acylated products, ester derivatives, and ester-forming derivatives such as acid halides.

[0046] Specific examples of monomers that give repeating units represented by formula [II] include, for example, 6-hydroxy-2-naphthoic acid and its acylids, ester derivatives, acid halides, and other ester-forming derivatives.

[0047] Specific examples of monomers that give repeating units represented by formula [III] include, for example, the aromatic diols hydroquinone, resorcinol, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl ether, and their alkyl, alkoxy or halogen-substituted derivatives, as well as ester-forming derivatives such as their acylated derivatives.

[0048] Specific examples of monomers that give repeating units represented by formula [IV] include, for example, the aromatic dicarboxylic acids terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 4,4'-dicarboxybiphenyl, and their alkyl, alkoxy, or halogen-substituted derivatives, as well as ester-forming derivatives such as ester derivatives and acid halides thereof.

[0049] Furthermore, among the all-aromatic liquid crystal polymers suitably used in the present invention, Ar1 and Ar2 relating to the repeating units represented by formulas [III] and [IV] are independent of each other, as shown in formulas (1) to (4). [ka] A fully aromatic liquid crystal polymer containing one or more aromatic groups selected from the group consisting of the aromatic groups represented by is even more preferably used.

[0050] Among these, the repeating units represented by formula [III] are particularly preferably those represented by aromatic groups (1) and (3), that is, those monomers that give rise to these repeating units, which are hydroquinone and 4,4'-dihydroxybiphenyl and their ester-forming derivatives, because the reactivity during polymerization and the mechanical properties, heat resistance, crystal melting temperature, and moldability of the resulting all-aromatic liquid crystal polymer can be easily adjusted to an appropriate level.

[0051] Furthermore, as the repeating units represented by formula [IV], it is particularly preferable to use aromatic groups represented by formulas (1), (2), and (4), that is, terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid and their ester-forming derivatives, as monomers that give rise to these repeating units, because it is easy to adjust the mechanical properties, heat resistance, crystal melting temperature, and moldability of the resulting all-aromatic liquid crystal polymer to appropriate levels.

[0052] In the repeating units described above, for example, if Ar1 (or Ar2) contains two or more aromatic groups, it means that the repeating units represented by formula [III] (or [IV]) are present in the total aromatic liquid crystal polymer in two or more types, depending on the type of divalent aromatic group. That is, formulas [III] and / or [IV] are preferred for total aromatic liquid crystal polymers in which Ar1 and Ar2 are, independently of each other, one or more repeating units in which aromatic groups are selected from the group consisting of formulas (1) to (4). In this case, the composition ratio r related to formula [III] (or the composition ratio s related to formula [IV]) represents the total composition ratio of the two or more repeating units.

[0053] In one preferred embodiment, p / q is 0.5 to 2.0, s and r are 5 to 15, and the repeating units represented by formulas [III] and [IV] are such that Ar1 in formula [III] and Ar2 in formula [IV] are aromatic groups represented by formula (1).

[0054] In another preferred embodiment, p / q is 0.5 to 2.0, s and r are 5 to 15, and the repeating units represented by formulas [III] and [IV] are such that Ar1 in formula [III] is the aromatic group represented by formula (3), and Ar2 in formula [IV] is the aromatic group represented by formulas (2) and (4).

[0055] Furthermore, in another preferred embodiment, p / q is 6 to 10, s and r are 25 to 35, and the repeating units represented by formulas [III] and [IV] are such that Ar1 in formula [III] is the aromatic group represented by formulas (1) and (3), and Ar2 in formula [IV] is the aromatic group represented by formula (1).

[0056] In the all-aromatic liquid crystal polymer suitably used in the present invention, the total composition ratio of repeating units [p+q+r+s] is preferably 100 mol%, but other repeating units may be further contained as long as the objective of the present invention is not impaired.

[0057] Monomers that provide other repeating units constituting the all-aromatic liquid crystal polymer suitably used in the present invention include other aromatic hydroxycarboxylic acids, aromatic hydroxyamines, aromatic diamines, aromatic aminocarboxylic acids, aromatic hydroxydicarboxylic acids, aromatic mercaptocarboxylic acids, aromatic dithiols, aromatic mercaptophenols, and combinations thereof.

[0058] Other specific examples of aromatic hydroxycarboxylic acids include, for example, 3-hydroxybenzoic acid, 2-hydroxybenzoic acid, 5-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 4'-hydroxyphenyl-4-benzoic acid, 3'-hydroxyphenyl-4-benzoic acid, 4'-hydroxyphenyl-3-benzoic acid and their alkyl, alkoxy, or halogen-substituted derivatives, as well as ester-forming derivatives such as acylids, ester derivatives, and acid halides.

[0059] The sum of the compositional ratios of the repeating units derived from these other monomer components is preferably 10 mol% or less in the total repeating units.

[0060] The method for producing the liquid crystal polymer used in this invention will be described below.

[0061] There are no particular limitations on the method for producing the liquid crystal polymer used in the present invention, and known polycondensation methods for forming ester bonds, amide bonds, etc., consisting of the above-mentioned combination of monomers, such as the molten acidolysis method, can be used.

[0062] The molten acidolysis method is a preferred method for producing the liquid crystal polymer used in the present invention. In this method, monomers are first heated to form a molten liquid of the reactants, and then the reaction is continued to obtain a molten polymer. Vacuum may be applied to facilitate the removal of volatile by-products (e.g., acetic acid, water, etc.) produced in the final stage of condensation.

[0063] In the melt acidolysis method, the polymerizable monomer component used to produce liquid crystal polymers can also be used in the reaction as a modified form in which the hydroxyl group and / or amino group are acylated at room temperature, i.e., as a lower acyled. The lower acyl group is preferably one having 2 to 5 carbon atoms, and more preferably one having 2 or 3 carbon atoms. Particularly preferred is a method in which the acetylated monomer is used in the reaction.

[0064] The monomer acylated product may be one that has been synthesized beforehand by acylation, or it may be generated in the reaction system by adding an acylation agent such as acetic anhydride to the monomer during the production of the liquid crystal polymer.

[0065] Furthermore, a catalyst may be used during the reaction as needed.

[0066] Specific examples of catalysts include organotin compounds (dialkyltin oxides such as dibutyltin oxide, diaryltin oxides, etc.), titanium dioxide, antimony trioxide, organotitanium compounds (alkoxytitanium silicate, titanium alkoxide, etc.), alkali and alkaline earth metal salts of carboxylic acids (potassium acetate, sodium acetate, etc.), Lewis acids (BF3, etc.), and gaseous acid catalysts such as hydrogen halides (HCl, etc.).

[0067] The amount of catalyst used is typically 1 to 1000 ppm, preferably 2 to 100 ppm, relative to the total amount of monomers.

[0068] The liquid crystal polymer obtained by this polycondensation reaction is removed from the polymerization reactor in a molten state and then processed into pellets, flakes, or powder.

[0069] The liquid crystal polymer content in the resin composition used in the present invention is 0.1 to 150 parts by mass per 100 parts by mass of polyamide resin, preferably 1 to 100 parts by mass, more preferably 5 to 90 parts by mass, even more preferably 10 to 85 parts by mass, particularly preferably 20 to 80 parts by mass, and most preferably 25 to 75 parts by mass.

[0070] If the liquid crystal polymer content is less than 0.1 parts by mass, the amount of liquid crystal polymer fine particles obtained will be small, and if it exceeds 150 parts by mass, no liquid crystal polymer fine particles will be obtained.

[0071] A compatibilizer may be added to improve the compatibility between the polyamide resin and the liquid crystal polymer and to control the particle size of the resulting liquid crystal polymer powder. When a compatibilizer is added, the amount added is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by weight of the polyamide resin.

[0072] The resin composition used in the present invention preferably does not contain any additives other than inorganic and / or organic fillers and compatibilizers, or other resin components.

[0073] The resin composition used in the present invention can be obtained by mixing a polyamide resin and a liquid crystal polymer, and optionally a compatibilizer, and melt-kneading them using a Banbury mixer, kneader, single-screw or twin-screw extruder, etc., at a temperature ranging from near the crystal melting temperature of the liquid crystal polymer to the crystal melting temperature + 40°C.

[0074] The present invention provides a method for producing liquid crystal polymer fine particles, which first involves a dissolution step in which a resin composition containing 100 parts by mass of the polyamide resin and 0.1 to 150 parts by mass of the liquid crystal polymer is mixed with a solvent to dissolve the polyamide resin contained in the resin composition (dissolution step). By dissolving the polyamide resin in the solvent within the resin composition, a dispersion of liquid crystal polymer fine particles is obtained using the polyamide resin solution as the dispersion medium.

[0075] The solvent used in the dissolution process can be any solvent that dissolves the polyamide resin but does not dissolve the liquid crystal polymer. For example, one or more solvents selected from the group consisting of p-cresol, o-cresol, m-cresol, phenol, tetrahydrofuran, dimethylformamide, water, methanol, ethanol, n-propanol, isopropanol, toluene, xylene, cyclohexane, methylcyclohexane, cyclohexanone, and methyl ethyl ketone can be used. Among these, it is preferable to include one or more solvents selected from the group consisting of p-cresol, o-cresol, m-cresol, phenol, water, methanol, ethanol, n-propanol, isopropanol, toluene, xylene, cyclohexane, methylcyclohexane, and methyl ethyl ketone, due to their high solubility in the polyamide resin, and it is more preferable to include one or more solvents selected from the group consisting of p-cresol, o-cresol, m-cresol, toluene, xylene, and methanol.

[0076] The amount of solvent used is not particularly limited as it varies depending on the type of solvent used, but the amount of solvent that dissolves the polyamide resin should be appropriately selected. For example, 100 to 5000 parts by mass of solvent per 100 parts by mass of polyamide resin.

[0077] The temperature in the dissolution process is not particularly limited as it varies depending on the type and amount of solvent used, but it should be carried out at a temperature at which the polyamide resin dissolves, for example, 20 to 200°C.

[0078] In the present invention, the liquid crystal polymer fine particle dispersion in the polyamide resin solution is then subjected to a dispersion medium removal step to remove the solution in which the polyamide resin is dissolved in the solvent.

[0079] The removal process is preferably carried out by solid-liquid separation of the dispersion of liquid crystal polymer fine particles by filtration or centrifugation. During solid-liquid separation, it is preferable to wash the liquid crystal polymer fine particles by adding a solvent as appropriate. The solvent used during solid-liquid separation is preferably the same as the solvent used to dissolve the polyamide resin.

[0080] High-purity liquid crystal polymer nanoparticles can be obtained by, for example, heating and drying them at a temperature above the boiling point of the solvent under normal pressure, or by drying them under reduced pressure and distilling off the solvent.

[0081] In the present invention, liquid crystal polymer fine particles mean that the liquid crystal polymer exists with an average particle size of 0.01 to 100 μm, preferably 0.05 to 50 μm, more preferably 0.1 to 10 μm, and even more preferably 0.1 to 5 μm. Having an average particle size of the liquid crystal polymer within the above range makes it suitable for various applications such as coating materials, powder materials for molded articles, and additives.

[0082] The average particle diameter refers to the median diameter (D50) obtained from the particle size distribution diagram using a laser diffraction / scattering particle size distribution analyzer.

[0083] The average sphericity (ratio of the longest axis to the shortest axis of the particle) of the liquid crystal polymer fine particles of the present invention is preferably 1.8 or less, more preferably 1.5 or less, even more preferably 1.3 or less, particularly preferably 1.2 or less, and most preferably 1 to 1.1.

[0084] In a preferred embodiment, the present invention also relates to liquid crystal polymer fine particles having an average particle diameter of 0.01 to 100 μm and an average sphericity of 1.8 or less.

[0085] The liquid crystal polymer fine particles of the present invention preferably contain 90% or more of particles with an average sphericity of 1.8 or less, more preferably 95% or more, and even more preferably 98% or more.

[0086] The average sphericity is calculated by observing SEM images of liquid crystal polymer microparticles taken with a scanning electron microscope (SEM), and using the average value of the longest axis / shortest axis values ​​for 100 or more arbitrarily selected liquid crystal polymer microparticles.

[0087] In the present invention, the obtained liquid crystal polymer fine particles may be dispersed again in a solvent to form a liquid crystal polymer fine particle dispersion (a dispersion using a solvent as a dispersion medium). That is, in a preferred embodiment, the present invention also relates to a liquid crystal polymer fine particle dispersion in which liquid crystal polymer fine particles having an average particle diameter of 0.01 to 100 μm and an average sphericity of 1.8 or less are dispersed in a solvent.

[0088] Furthermore, in another preferred embodiment of the present invention, the liquid crystal polymer fine particle dispersion (a dispersion using a polyamide resin solution as a dispersion medium) obtained in the dissolution step may be used as is. That is, the present invention also relates to a liquid crystal polymer fine particle dispersion containing 100 parts by mass of polyamide resin and 0.1 to 150 parts by mass of liquid crystal polymer, wherein the polyamide resin is dissolved in the solvent, and liquid crystal polymer fine particles having an average particle diameter of 0.01 to 100 μm and an average sphericity of 1.8 or less are dispersed in the polyamide resin solution.

[0089] Liquid crystal polyester fine particles or liquid crystal polymer fine particle dispersions obtained by the manufacturing method described above can be applied to a variety of uses. Examples include powder coatings for electrostatic painting, coating materials, insulating organic fillers, raw materials for sliding materials, powder materials for molded articles, and additives.

[0090] The solvent for the liquid crystal polymer fine particle dispersion can be any solvent that dissolves the polyamide resin but does not dissolve the liquid crystal polymer. For example, one or more solvents selected from the group consisting of p-cresol, o-cresol, m-cresol, phenol, tetrahydrofuran, dimethylformamide, water, methanol, ethanol, n-propanol, isopropanol, toluene, xylene, cyclohexane, methylcyclohexane, cyclohexanone, and methyl ethyl ketone can be used. Among these, it is preferable to include one or more solvents selected from the group consisting of p-cresol, o-cresol, m-cresol, phenol, water, methanol, ethanol, n-propanol, isopropanol, toluene, xylene, cyclohexane, methylcyclohexane, and methyl ethyl ketone, due to their high solubility in the polyamide resin, and more preferably to include one or more solvents selected from the group consisting of p-cresol, o-cresol, m-cresol, toluene, xylene, and methanol.

[0091] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. [Examples]

[0092] Each physical property value in the examples was measured by the following method.

[0093] <Crystal melting temperature> Measurements were performed using a differential scanning calorimeter (DSC) Exstar6000 manufactured by Seiko Instruments Inc. A liquid crystal polymer sample was measured under a heating condition of 20°C / min from room temperature. After observing the endothermic peak temperature (Tm1), the sample was held at a temperature 20-50°C higher than Tm1 for 10 minutes. Next, the sample was cooled to room temperature under a cooling condition of 20°C / min. The endothermic peak was then observed again under the heating condition of 20°C / min, and the temperature at which the peak top was observed was defined as the crystal melting temperature of the liquid crystal polymer.

[0094] <Average particle size> The median diameter (D50) was measured using the Microtrac MT3000 laser diffraction / scattering particle size distribution analyzer manufactured by Microtrac-Bell, Inc.

[0095] <IR> This was confirmed using a Fourier transform infrared spectrophotometer FT / IR-4600 manufactured by JASCO Corporation.

[0096] <SEM> SEM images were acquired using a Hitachi High-Tech S-4300 scanning electron microscope.

[0097] <Average sphericity> The values ​​were calculated by observing SEM images of liquid crystal polymer microparticles and using the average of the longest axis / shortest axis values ​​for 100 or more arbitrarily selected liquid crystal polymer microparticles.

[0098] In the examples, the following abbreviations represent the following compounds. LCP: Liquid Crystal Polymer POB: 4-Hydroxybenzoic acid BON6: 6-hydroxy-2-naphthoic acid HQ: Hydroquinone BP:4,4 ’ -Dihydroxybi TPA: Terephthalic acid IPA: Isophthalic Acid NDA: 2,6-Naphthalenedicarboxylic acid

[0099] (Polyamide resin) The following polyamide resins were used: Polyamide 6 (PA1): Unitika Nylon 6 "A1030BRL" manufactured by Unitika Ltd. (crystal melting temperature 220℃) Polyamide 66 (PA2): Unitika Nylon 66 "E2000" manufactured by Unitika Ltd. (crystal melting temperature 260℃) Polymerized fatty acid polyamide (PA3): "PA-100A-S" manufactured by T&K TOKA Corporation (crystal melting temperature 136℃)

[0100] (Synthesis of liquid crystal polymer 1) In a reaction vessel equipped with a torque meter-equipped stirrer and distillation tube, POB, BON6, HQ, and TPA were charged to a total volume of 6.5 moles. Acetic anhydride was then added at a concentration of 1.025 moles relative to the total amount of hydroxyl groups of the monomers, and deacetic acid polymerization was carried out under the following conditions: The mixture was heated from room temperature to 150°C over 1 hour under a nitrogen gas atmosphere and held at this temperature for 30 minutes. Next, the temperature was rapidly increased to 210°C while distilling off the by-product acetic acid, and held at this temperature for 30 minutes. Afterward, the temperature was increased to 335°C over 3 hours, and then the pressure was reduced to 20 mmHg over 30 minutes. The polymerization reaction was terminated when the predetermined torque was reached, the contents were removed from the reaction vessel, and pellets of liquid crystal polymer 1 were obtained using a pulverizer. The amount of acetic acid distilled during polymerization was approximately as per the theoretical value. The crystal melting temperature of the obtained liquid crystal polymer 1 (LCP1) was 218°C. POB: 359.5 g (40 moles) BON6: 489.8 g (40 moles) HQ: 71.7 g (10 moles) TPA: 108.0 g (10 moles)

[0101] (Synthesis of liquid crystal polymer 2) In a reaction vessel equipped with a torque meter-equipped stirrer and distillation tube, POB, BON6, BP, NDA, and IPA were charged in the composition ratios shown below to a total volume of 6.5 moles. Acetic anhydride was then added at a concentration of 1.03 moles relative to the total amount of hydroxyl groups of the monomers, and deacetic acid polymerization was carried out under the following conditions: The mixture was heated from room temperature to 150°C in 1 hour under a nitrogen gas atmosphere and held at that temperature for 30 minutes. Next, the temperature was rapidly increased to 210°C while distilling off the by-product acetic acid and held at that temperature for 30 minutes. Afterward, the temperature was increased to 340°C over 4 hours, and then the pressure was reduced to 10 mmHg over 80 minutes. The polymerization reaction was terminated when the predetermined torque was reached, the contents of the reaction vessel were removed, and pellets of liquid crystal polymer 2 were obtained using a pulverizer. The amount of acetic acid distilled during polymerization was approximately as per the theoretical value. The crystal melting temperature of the obtained liquid crystal polymer 2 (LCP2) was 183°C. POB: 386.0g (43 moles) BON6: 403.6g (33 moles) BP: 145.2g (12 moles) NDA: 126.0g (9 moles) IPA: 32.4g (3 moles)

[0102] (Synthesis of liquid crystal polymer 3) In a reaction vessel equipped with a torque meter-equipped stirrer and distillation tube, POB, BON6, BP, HQ, and TPA were charged in the composition ratios shown below, totaling 6.5 moles. Acetic anhydride was then added at a concentration of 1.03 moles relative to the total amount of hydroxyl groups (moles) of the monomers. Deacetic acid polymerization was carried out under the following conditions: The mixture was heated from room temperature to 150°C in 1 hour under a nitrogen gas atmosphere and held at that temperature for 30 minutes. Next, the mixture was heated to 350°C over 7 hours while distilling off the by-product acetic acid, and then the pressure was reduced to 5 mmHg over 80 minutes. The polymerization reaction was terminated when the predetermined torque was reached, the contents of the reaction vessel were removed, and pellets of liquid crystal polymer 3 were obtained using a pulverizer. The amount of acetic acid distilled during polymerization was approximately as per the theoretical value. The crystal melting temperature of the obtained liquid crystal polymer 3 (LCP3) was 335°C. POB: 314.2g (35 moles) BON6: 61.2g (5 moles) HQ: 114.5g (16 moles) BP: 169.4g (14 moles) TPA: 323.9g (30 moles)

[0103] (Preparation of resin composition) Polyamide resin and LCP were blended in the quantities shown in Table 1, and the mixture was melt-kneaded using a twin-screw extruder (TEX-30, manufactured by Japan Steel Works Ltd.) at the cylinder temperatures shown in Table 1 to obtain resin composition pellets.

[0104] [Table 1]

[0105] [Example 1] 5.0 g of resin composition 1 pellets and 100.0 g of p-cresol were added to a 500 mL four-necked flask and heated to approximately 200°C with stirring, then refluxed to obtain a white suspension (liquid crystal polymer microparticle dispersion). The white suspension was placed in a centrifuge tube and centrifuged at 25°C and 20000 G for 1 hour. The supernatant became almost transparent, so it was removed by decantation, and the precipitate was vacuum-dried at 70°C for 6 hours to obtain 1.3 g of liquid crystal polymer microparticles. The obtained liquid crystal polymer microparticles were confirmed to be liquid crystal polymers by IR (infrared spectroscopy). The average particle size of the obtained liquid crystal polymer microparticles was measured using a particle size distribution analyzer. In addition, the average sphericity was measured from SEM images. The results are shown in Table 2, and the SEM images are shown in Figure 1.

[0106] [Example 2] The procedure was carried out in the same manner as in Example 1, except that resin composition 1 was replaced with resin composition 2, to obtain 0.6 g of liquid crystal polymer fine particles. The average particle size and average sphericity of the obtained liquid crystal polymer fine particles were measured. The results are shown in Table 2.

[0107] [Example 3] The procedure was carried out in the same manner as in Example 1, except that resin composition 1 was replaced with resin composition 3, and 0.8 g of liquid crystal polymer fine particles were obtained. The average particle size and average sphericity of the obtained liquid crystal polymer fine particles were measured. The results are shown in Table 2.

[0108] [Example 4] (Reference example) The procedure was carried out in the same manner as in Example 1, except that resin composition 1 was replaced with resin composition 4, to obtain 0.8 g of liquid crystal polymer fine particles. The average particle size and average sphericity of the obtained liquid crystal polymer fine particles were measured. The results are shown in Table 2.

[0109] [Example 5] 5.0 g of resin composition 5 pellets, 22.5 g of methanol, and 22.5 g of toluene were added to a 300 mL four-necked flask and heated to approximately 65°C with stirring, then refluxed to obtain a white suspension (liquid crystal polymer microparticle dispersion). The white suspension was placed in a centrifuge tube and centrifuged at 25°C and 20000 G for 1 hour. The supernatant became almost transparent, so it was removed by decantation, and the precipitate was vacuum-dried at 70°C for 6 hours to obtain 1.1 g of liquid crystal polymer microparticles. The obtained liquid crystal polymer microparticles were confirmed to be liquid crystal polymers by IR (infrared spectroscopy). The average particle size of the obtained liquid crystal polymer microparticles was measured using a particle size distribution analyzer. In addition, the average sphericity was measured from SEM images.

[0110] [Comparative Example 1] 5.0 g of pellets from resin composition 6 and 100.0 g of p-cresol were added to a 500 mL four-necked flask and heated to approximately 200°C while stirring, then refluxed for 1 hour. However, the pellets remained in their original shape, and no spherical particles were obtained.

[0111] [Comparative Example 2] 10.0g of liquid crystal polymer 1 pellets were rotated at 8000 x 8000 min⁻¹ using a Sugino Machine Co., Ltd. dry strut DB-180W. -1 Although the material was ground down, it resulted in fibrous material, and spherical fine particles were not obtained. A microscope image is shown in Figure 2.

[0112] [Table 2]

[0113] As is clear from Table 2, the liquid crystal polymer fine particles obtained in Examples 1 to 5 all have a sphericity of 1.8 or less, indicating that they are spherical fine particles.

Claims

1. A resin composition comprising 100 parts by mass of polyamide resin and 0.1 to 150 parts by mass of liquid crystal polymer having a crystal melting temperature of 150 to 250°C is mixed with a solvent to dissolve the polyamide resin contained in the resin composition, thereby obtaining a dispersion of liquid crystal polymer fine particles in a polyamide resin solution, and A step of removing the polyamide resin solution from the dispersion, Includes, Here, the difference between the crystal melting temperatures of the polyamide resin and the liquid crystal polymer contained in the resin composition is 100°C or less. A method for producing liquid crystal polymer fine particles with an average particle size of 0.01 to 1.98 μm.

2. The method according to claim 1, wherein the polyamide resin comprises one or more selected from the group consisting of polyamide 6, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 6T, polyamide 6I, polyamide 9T, polyamide 46, polyamide MXD6, and polymerized fatty acid polyamide.

3. Liquid crystal polymers are given by formulas [I] and [II] 【Chemistry 1】 The method according to claim 1, wherein the polymer is a fully aromatic liquid crystal polymer containing repeating units represented by .

4. Liquid crystal polymers are given by formulas [I] to [IV] 【Chemistry 2】 [In the formula, Ar １ and Ar ２ Each represents one or more divalent aromatic groups, and p, q, r, and s are the composition ratios (mol%) of each repeating unit in the liquid crystal polymer, satisfying the following conditions: 0.5 ≤ p / q, 5 ≤ r ≤ 35, and [5 ≤ s ≤ 35] The method according to claim 1, wherein the polymer is a fully aromatic liquid crystal polymer containing repeating units represented by .

5. Formula [III] and / or formula [IV] are Ar １ and Ar ２ However, they are independent of each other, as shown in equations (1) to (4). 【Transformation 3】 The method according to claim 4, which is a fully aromatic liquid crystal polymer comprising one or more repeating units that are aromatic groups selected from the group consisting of the above.

6. The method according to claim 1, wherein the crystal melting temperature of the liquid crystal polymer is 170 to 250°C.

7. The method according to claim 1, wherein the resin composition is a molten kneaded product containing a polyamide resin and a liquid crystal polymer.

8. The method according to claim 1, wherein the solvent comprises one or more selected from the group consisting of p-cresol, o-cresol, m-cresol, phenol, water, methanol, ethanol, n-propanol, isopropanol, toluene, xylene, cyclohexane, methylcyclohexane, and methyl ethyl ketone.

9. The method according to claim 1, wherein the amount of solvent to be mixed with the resin composition is 100 to 5000 parts by mass per 100 parts by mass of polyamide resin.

10. Liquid crystal polymer fine particles having an average particle diameter of 0.01 to 1.98 μm, an average sphericity of 1.8 or less, and a crystal melting temperature of 150 to 250°C.

11. A dispersion of liquid crystal polymer microparticles, wherein liquid crystal polymer microparticles having an average particle diameter of 0.01 to 1.98 μm, an average sphericity of 1.8 or less, and a crystal melting temperature of 150 to 250°C are dispersed in a solvent.

12. A dispersion of liquid crystal polymer fine particles comprising 100 parts by mass of polyamide resin and 0.1 to 150 parts by mass of liquid crystal polymer having a crystal melting temperature of 150 to 250°C, wherein the difference between the crystal melting temperatures of the polyamide resin and liquid crystal polymer contained in the resin composition is 100°C or less, the polyamide resin is dissolved in the solvent, and liquid crystal polymer fine particles having an average particle diameter of 0.01 to 1.98 μm and an average sphericity of 1.8 or less are dispersed in the polyamide resin solution.

13. The dispersion according to claim 11 or 12, wherein the solvent comprises one or more selected from the group consisting of p-cresol, o-cresol, m-cresol, phenol, water, methanol, ethanol, n-propanol, isopropanol, toluene, xylene, cyclohexane, methylcyclohexane, and methyl ethyl ketone.

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