Liquid crystal polyester resin particles, dispersion, laminate, resin film, and method for producing the same

Abstract

To provide liquid crystal polyester resin particles having stable tensile characteristics and dielectric characteristics when formed into a film.SOLUTION: Liquid crystal polyester resin particles have a volume average particle diameter of 0.1-50 μm, and a purified linseed oil absorption amount calculated according to JIS K 5101 (2004) of 10-300 mL / 100 g.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to liquid crystal polyester resin particles, a dispersion, a laminate, and a resin film. More specifically, it relates to liquid crystal polyester resin particles, a dispersion, and a laminate and a resin film obtained using the same.

Background Art

[0002] With the increasing demand for mobile terminals and communication base stations in recent years, the demand for resins used in printed circuit boards such as rigid boards and flexible boards has been expanding. Furthermore, in recent years, the use of fifth-generation mobile communication "5G" has started, and for resins for these substrate applications, high performance such as low dielectric characteristics at high frequencies has been required, and liquid crystal polyester resins with excellent low dielectric characteristics have attracted attention.

[0003] On the other hand, liquid crystal polyester resin is a resin that forms an anisotropic molten phase and has the property of orienting in the resin flow direction during molding and cooling. Therefore, the resulting molded product often has different physical properties in the resin flow direction and the direction perpendicular to it. Therefore, as a technique for granulating liquid crystal polyester resin and processing it after eliminating anisotropy, it has been proposed to obtain a liquid crystal polyester resin film by applying a dispersion of powder of liquid crystal polyester resin dispersed in a medium, removing the dispersion, and performing heat treatment (for example, Patent Document 1).

[0004] Also, as an example of processing liquid crystal polyester resin particles, examples have been proposed in which the dielectric characteristics of other resins are improved by adding liquid crystal polyester resin particles to other resins such as epoxy resin and polyimide resin (for example, Patent Documents 2 and 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] In the method described in Patent Document 1, there are problems with the dispersibility in the medium, and there are problems that the tensile properties and dielectric properties of the obtained film are not stable. Also, in the methods described in Patent Documents 2 and 3, there are problems with the dispersibility in other resins or solvents in which other resins dissolve, and there are problems that the tensile properties and dielectric properties of molded products such as the obtained film are not stable.

[0007] An object of the present invention is to provide a liquid crystal polyester resin powder, a resin composition, a molded product obtained therefrom, and a manufacturing method that have stable tensile properties and dielectric properties when formed into a film. [Means for Solving the Problems]

[0008] As a result of intensive studies to solve the above problems, the present inventors have found that liquid crystal polyester resin particles having a volume average particle diameter and an oil absorption amount of purified linseed oil calculated according to JIS K 5101 (2004) within a specific range have stable tensile properties and dielectric properties when formed into a film, and have reached the present invention. That is, the present invention is as follows: (1) The number average molecular weight of the liquid crystal polyester resin constituting the liquid crystal polyester resin particles is 12,000 or more, Liquid crystal polyester resin particles having a volume average particle diameter of 0.1 to 50 μm and an oil absorption amount of purified linseed oil calculated according to JIS K 5101 (2004) of 10 to 300 mL / 100 g. (2) A dispersion in which the above liquid crystal polyester resin particles are dispersed in at least one medium (A) selected from a thermosetting resin, a thermoplastic resin, and a dispersion medium. (3) A method for manufacturing a laminate, in which the above dispersion is applied onto a support, and liquid removal and / or heat treatment is performed to obtain a laminate. A method for producing a resin film, comprising removing a support from the laminate obtained by the above method to obtain a resin film.

Advantages of the Invention

[0009] The liquid crystal polyester resin particles of the present invention have stable tensile properties and dielectric properties when formed into a film. A film obtained from such resin particles is suitable for laminates used in flexible printed wiring boards, semiconductor packages, etc. within electrical and electronic components and mechanical components.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described in detail.

[0011] <Liquid crystal polyester resin> A liquid crystal polyester resin is a polyester that forms an anisotropic molten phase. Examples of such polyester resins include polyesters composed of structural units selected to form an anisotropic molten phase from, for example, oxycarbonyl units, dioxy units, dicarbonyl units, etc. described later. Next, the structural units constituting the liquid crystal polyester resin will be described. Specific examples of oxycarbonyl units include structural units generated from aromatic hydroxycarboxylic acids such as p-hydroxybenzoic acid, m-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, etc. From the viewpoint of being able to control the oil absorption amount of purified linseed oil within a specific range and obtaining stable tensile properties and dielectric properties, structural units generated from 6-hydroxy-2-naphthoic acid are preferred.

[0012] The content of 6-hydroxy-2-naphthoic acid is preferably 30 mol% or more, more preferably 35 mol% or more, still more preferably 40 mol% or more, and particularly preferably 45 mol% or more with respect to 100 mol% of all structural units of the liquid crystal polyester resin, from the viewpoint that it can control the oil absorption amount of the refined waste oil to a specific range and provide stable tensile properties and dielectric properties. On the other hand, the content of 6-hydroxy-2-naphthoic acid is preferably 72 mol% or less, more preferably 70 mol% or less, from the viewpoint that polymerization can be easily controlled, and the oil absorption amount of the refined waste oil can be controlled within a suitable range to provide stable tensile properties and dielectric properties.

[0013] Specific examples of the dioxy unit include structural units formed from aromatic diols such as 4,4'-dihydroxybiphenyl, hydroquinone, resorcinol, t-butylhydroquinone, phenylhydroquinone, chloro-hydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 3,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxybenzophenone; structural units formed from aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol; and structural units formed from alicyclic diols such as 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol. From the viewpoint of easy expression of liquid crystallinity and stable tensile properties and dielectric properties, structural units formed from 4,4'-dihydroxybiphenyl, hydroquinone, and ethylene glycol are preferred.

[0014] Specific examples of the dicarbonyl unit include structural units formed from aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 3,3'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid, 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, etc., structural units formed from aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, hexahydroterephthalic acid, etc., and structural units formed from alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, etc. From the viewpoint of easy expression of liquid crystallinity and stable tensile properties and dielectric properties, structural units formed from aromatic dicarboxylic acids are preferred, and among them, structural units formed from terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are particularly preferred.

[0015] The liquid crystal polyester resin used in the present invention can control the oil absorption amount of the purified waste liquor to a specific range as described later. From the viewpoint of stable tensile properties and dielectric properties, it is preferably contained 30 mol% or more of the following structural unit (I) with respect to 100 mol% of all the structural units of the liquid crystal polyester resin, more preferably 35 mol% or more, still more preferably 40 mol% or more, and particularly preferably 45 mol% or more. On the other hand, the content of the structural unit (I) can control the oil absorption amount of the purified waste liquor to a suitable range as described later. From the viewpoint of stable tensile properties and dielectric properties, it is preferably 72 mol% or less, more preferably 70 mol% or less.

[0016]

Chemical formula

[0017] (X and Y each independently represent an oxygen atom or a carbonyl group.) Specific examples of the structural unit (I) include structural units formed from 6-hydroxy-2-naphthoic acid, 2,6-dihydroxynaphthalene, and 2,6-naphthalenedicarboxylic acid, and one or more of them can be used. However, it is preferable to contain 6-hydroxy-2-naphthoic acid as an essential component.

[0018] The liquid crystal polyester resin used in the present invention contains almost no highly polar amide groups, and from the viewpoint of controlling the oil absorption amount of the refined waste oil described later within a specific range and achieving stable tensile properties and dielectric properties, with respect to 100 mol% of all the structural units of the liquid crystal polyester resin, the following structural unit (II) is preferably 3 mol% or less, more preferably 2 mol% or less, and even more preferably 1 mol% or less. The structural unit (II) may be 0 mol%. -Z-Ar-NH- (II) (Ar represents a naphthalenediyl group or a phenylene group, and the hydrogen atoms in the naphthalenediyl group or the phenylene group may each independently be substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. Z represents O, C=O, or NH.)

[0019] The content of each structural unit of the liquid crystal polyester resin in the present invention can be determined by pulverizing the liquid crystal polyester resin pellets, adding tetramethylammonium hydroxide, and performing pyrolysis GC / MS measurement using Shimadzu GCMS-QP5050A. The content of the structural unit that was not detected or was below the detection limit is calculated as 0 mol%.

[0020] From the viewpoint of heat resistance, the melting point (Tm) of the liquid crystal polyester resin used in the present invention is preferably 200°C or higher, more preferably 250°C or higher, even more preferably 280°C or higher, and particularly preferably 300°C or higher. On the other hand, the upper limit of the melting point (Tm) of the liquid crystal polyester resin is not particularly limited and may be 400°C or higher.

[0021] The melting point (Tm) is measured by differential scanning calorimetry. Specifically, first, the polymer to be measured is heated from room temperature under a temperature increase condition of 20 °C / min to observe the endothermic peak temperature (Tm1). After observing the endothermic peak temperature (Tm1), the polymer is held at a temperature of the endothermic peak temperature (Tm1) + 20 °C for 5 minutes. Then, the polymer is cooled to room temperature under a temperature decrease condition of 20 °C / min. And then, the polymer is heated again under a temperature increase condition of 20 °C / min to observe the endothermic peak temperature (Tm2). The melting point (Tm) in the present invention refers to the endothermic peak temperature (Tm2) in the second heating process.

[0022] From the viewpoint of excellent strength, the melt viscosity of the liquid crystal polyester resin used in the present invention is preferably 20 Pa·s or more, more preferably 30 Pa·s or more, and even more preferably 40 Pa·s or more. On the other hand, the upper limit of the melt viscosity of the liquid crystal polyester resin is not particularly limited, but it may be a melt viscosity within a preferable range of the absolute number average molecular weight described later.

[0023] This melt viscosity is a value measured by a high-pressure type flow tester under the conditions of a temperature of the melting point (Tm) of the liquid crystal polyester resin + 10 °C, or 280 °C when Tm is less than 270 °C, and a shear rate of 1000 / second.

[0024] From the viewpoint that the oil absorption amount of the refined waste oil described later can be controlled within a specific range and stable tensile properties and dielectric properties can be obtained, the absolute number average molecular weight of the liquid crystal polyester resin used in the present invention is preferably 12,000 or more, more preferably 13,000 or more, even more preferably 14,000 or more, and particularly preferably 15,000 or more. On the other hand, from the viewpoint that the oil absorption amount of the refined waste oil described later can be controlled within a specific range and stable tensile properties and dielectric properties can be obtained, the absolute number average molecular weight is preferably 50,000 or less, more preferably 40,000 or less, and even more preferably 30,000 or less.

[0025] Note that the number-average molecular weight can be measured by the GPC / light scattering method (gel permeation chromatography / light scattering method) using a solvent in which the liquid crystal polyester resin is soluble as an eluent. Examples of the solvent in which the liquid crystal polyester is soluble include halogenated phenols and a mixed solvent of a halogenated phenol and a general organic solvent. Preferably, it is pentafluorophenol or a mixed solvent of pentafluorophenol and chloroform, and among them, a pentafluorophenol / chloroform mixed solvent is particularly preferable from the viewpoint of handleability.

[0026] <Method for producing liquid crystal polyester resin> The method for producing the liquid crystal polyester resin used in the present invention is not particularly limited and can be produced according to the known polycondensation method of polyester resins. Specifically, taking as an example a liquid crystal polyester resin composed of a structural unit derived from p-hydroxybenzoic acid, a structural unit derived from 6-hydroxy-2-naphthoic acid, a structural unit derived from 4,4'-dihydroxybiphenyl, a structural unit derived from terephthalic acid, a structural unit derived from isophthalic acid, and a structural unit derived from ethylene glycol, the following can be mentioned.

[0027] (1) A method for producing a liquid crystal polyester resin by a deacetylation polycondensation reaction from p-acetoxybenzoic acid, 6-acetoxy-2-naphthoic acid, and 4,4'-diacetoxybiphenyl, terephthalic acid, isophthalic acid, a polyester polymer or oligomer such as polyethylene terephthalate, or bis(β-hydroxyethyl) terephthalate.

[0028] (2) A method for producing a liquid crystal polyester resin by reacting p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4,4'-dihydroxybiphenyl, terephthalic acid, isophthalic acid, a polyester polymer or oligomer such as polyethylene terephthalate, or bis(β-hydroxyethyl) terephthalate with acetic anhydride to acetylate phenolic hydroxyl groups and then performing deacetylation polymerization.

[0029] Among others, a method for producing a liquid crystal polyester resin by reacting acetic anhydride with a polyester polymer, oligomer, or bis(β-hydroxyethyl) terephthalate such as (2) p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4,4'-dihydroxybiphenyl, terephthalic acid, isophthalic acid, polyethylene terephthalate, etc. to acetylate phenolic hydroxyl groups and then subjecting it to deacetylation polymerization is preferably used because it is industrially excellent in controlling the degree of polymerization of the liquid crystal polyester resin.

[0030] In the method for producing the liquid crystal polyester resin used in the present invention, the temperature of the reaction for acetylating phenolic hydroxyl groups (acetylation reaction) is usually in the range of 130 to 210°C, preferably in the range of 130 to 150°C. The acetylation reaction time is usually carried out for 30 minutes or more from the viewpoint of polymerization reactivity, but it is preferably longer than 2 hours, more preferably 2 hours and 30 minutes or more, from the viewpoint that the oil absorption amount of the purification residue described later can be controlled within a suitable range and stable tensile properties and dielectric properties can be obtained. On the other hand, the acetylation reaction time is usually carried out within 6 hours from the viewpoint of productivity, but it is preferably 4 hours or less, more preferably 3 hours and 30 minutes or less, from the viewpoint that the oil absorption amount of the purification residue described later can be controlled within a suitable range and stable tensile properties and dielectric properties can be obtained.

[0031] The amount of acetic anhydride used in the acetylation reaction is usually 1.00 equivalent or more of the total phenolic hydroxyl groups in the liquid crystal polyester raw material from the viewpoint of polymerization reactivity, but it is preferably 1.10 equivalent or more, more preferably 1.11 equivalent or more, from the viewpoint that the oil absorption amount of the purification residue described later can be controlled within a suitable range and stable tensile properties and dielectric properties can be obtained. On the other hand, the amount of acetic anhydride used is usually 1.20 equivalent or less from the viewpoint of suppressing foreign substances derived from the chain of aromatic hydroxycarboxylic acids, but it is preferably 1.14 equivalent or less, more preferably 1.13 equivalent or less, from the viewpoint that the oil absorption amount of the purification residue described later can be controlled within a suitable range and stable tensile properties and dielectric properties can be obtained.

[0032] As a method for producing the liquid crystal polyester resin used in the present invention, it is also possible to complete the polycondensation reaction by the solid-phase polymerization method. The solid-phase polymerization method is preferable from the viewpoint of easily controlling the molecular weight within the above-mentioned preferable range. Examples of the treatment by the solid-phase polymerization method include the following methods. First, the polymer or oligomer of the liquid crystal polyester resin is pulverized by a pulverizer. The pulverized polymer or oligomer is heated under a nitrogen stream or under reduced pressure and polycondensed to a desired degree of polymerization to complete the reaction. The above heating is preferably carried out for 1 to 50 hours in the range of the melting point of the liquid crystal polyester resin - 50°C to the melting point - 5°C.

[0033] The polycondensation reaction of the liquid crystal polyester resin proceeds even without a catalyst, but stannous acetate, tetrabutyl titanate, potassium acetate, sodium acetate, antimony trioxide, magnesium metal, etc. can also be used as a catalyst.

[0034] <Liquid crystal polyester resin particles> The liquid crystal polyester resin particles of the present invention contain the above liquid crystal polyester resin as a main component. Preferably, the above liquid crystal polyester resin is 80% by weight or more, more preferably 90% by weight or more, still more preferably 95% by weight or more of the mass of the liquid crystal polyester resin particles, and the upper limit is 100% by weight.

[0035] The shape of the liquid crystal polyester resin particles is not particularly limited, and examples include spherical (including substantially spherical), spindle-shaped, irregular particle-shaped, fibril-shaped, fibrous, and mixtures thereof, but are not limited thereto.

[0036] The liquid crystal polyester resin particles of the present invention are characterized in that the volume average particle diameter is 0.1 to 50 μm. When the volume average particle diameter is less than 0.1 μm, aggregation between particles is likely to occur, and stable tensile properties and dielectric properties cannot be obtained in the film produced from the particles. From the viewpoint of suppressing aggregation between particles and obtaining stable tensile properties and dielectric properties in the film produced from the particles, the volume average particle diameter is preferably 0.3 μm or more, more preferably 0.7 μm or more, and still more preferably 1 μm or more. On the other hand, when the volume average particle diameter is larger than 50 μm, the surface becomes inhomogeneous, and stable tensile properties and dielectric properties cannot be obtained in the film produced from the particles. From the viewpoint of making the surface homogeneous and obtaining stable tensile properties and dielectric properties, the volume average particle diameter is preferably 40 μm or less, more preferably 30 μm or less, and still more preferably 20 μm or less.

[0037] The volume average particle diameter of the liquid crystal polyester resin particles of the present invention can be measured, for example, by the wet laser diffraction / scattering method (manufactured by Nikkiso Co., Ltd., model: Microtrac MT3300EXII), using water as the dispersion medium for measurement, setting the refractive index of the substance to 1.53 and the refractive index of the dispersion medium to 1.333, and measuring with a liquid crystal polyester resin particle dispersion liquid in which the liquid crystal polyester resin particles are preliminarily dispersed in ion-exchanged water.

[0038] The purified linseed oil absorption amount (hereinafter, may be referred to as the purified linseed oil absorption amount) of the liquid crystal polyester resin particles of the present invention, calculated in accordance with JIS K 5101 (2004), is characterized by being 10 to 300 mL / 100 g. The purified linseed oil absorption amount within the above range means that it is relatively smaller than that of general liquid crystal polyester resin particles. When the purified linseed oil absorption amount is less than 10 mL / 100 g, aggregation of particles is likely to occur when dispersed in a dispersion medium, and stable tensile properties and dielectric properties cannot be obtained in a film made from the particles. From the viewpoint of suppressing aggregation of particles when dispersed in a dispersion medium and obtaining stable tensile properties and dielectric properties in a film made from the particles, the purified linseed oil absorption amount is preferably 15 mL / 100 g or more, more preferably 20 mL / 100 g or more, still more preferably 25 mL / 100 g or more, and particularly preferably 30 mL / 100 g or more. On the other hand, when the purified linseed oil absorption amount is greater than 300 mL / 100 g, good fluidity cannot be achieved when dispersed in a dispersion medium, and the surface becomes more heterogeneous, and stable tensile properties and dielectric properties cannot be obtained in a film made from the particles. From the viewpoint of showing good fluidity when dispersed in a dispersion medium and having a homogeneous surface, and thus obtaining stable tensile properties and dielectric properties in a film made from the particles, the purified linseed oil absorption amount is preferably 270 mL / 100 g or less, more preferably 240 mL / 100 g or less, still more preferably 200 mL / 100 g or less, and particularly preferably 150 mL / 100 g or less.

[0039] The purified linseed oil absorption amount of the liquid crystal polyester resin particles of the present invention can be measured in accordance with the Japanese Industrial Standard (JIS standard) JIS K 5101 (2004) "Pigment Test Method - Purified Linseed Oil Method". For example, approximately 100 mg of the liquid crystal polyester resin particles are precisely weighed on a watch glass, and purified linseed oil (manufactured by Kanto Chemical Co., Inc.) is gradually added drop by drop with a burette. After kneading with a palette knife, the dropping-kneading is repeated until a lump of the sample is formed, and the point at which the paste becomes smooth and hard is taken as the end point, and it can be measured from the amount of purified linseed oil used for dropping.

[0040] After setting the volume average particle diameter to 0.1 to 50 μm, in order to control the oil absorption amount of the purified liquid crystal polyester resin particles within the above range, a method of making the polarity of the liquid crystal polyester resin relatively small can be mentioned. For example, a method that satisfies any of the following (1) or (2) and also satisfies the conditions of (3) or (4) can be mentioned. It is more preferable if the following (5) is satisfied. By the methods of the following (1) to (5), polar end groups such as hydroxyl groups and carboxyl groups, or ester groups and amide groups in the liquid crystal polyester resin can be reduced, and the polarity of the liquid crystal polyester resin can be made relatively small. (1) During the production of the liquid crystal polyester resin, the acetylation reaction, which is usually carried out at 130 to 150 °C, is carried out for more than 2 hours and 4 hours or less, or within the aforementioned preferable range. (2) During the production of the liquid crystal polyester resin, the charged amount of acetic anhydride used for acetylation is more than 1.10 equivalents and 1.14 equivalents or less of the total phenolic hydroxyl groups, or within the aforementioned preferable range. (3) The number average molecular weight of the liquid crystal polyester resin is 12,000 or more, or within the aforementioned preferable range. (4) The liquid crystal polyester resin has 30 to 72 mol% of structural unit (I) with respect to 100 mol% of all the structural units of the liquid crystal polyester resin, or within the aforementioned preferable range. (5) The liquid crystal polyester resin has 3 mol% or less of structural unit (II) with respect to 100 mol% of all the structural units of the liquid crystal polyester resin, or within the aforementioned preferable range. Also, from the viewpoint of controlling the oil absorption amount of the purified excess within the above range, it is preferable to perform acetylation without a catalyst and satisfy (1) or (2).

[0041] The method for producing the liquid crystal polyester resin particles of the present invention is not particularly limited. However, during the production of the liquid crystal polyester resin, a method of pulverizing the liquid crystal polyester resin discharged at a die temperature below the end point on the high-temperature side of the endothermic peak indicating the melting temperature in a differential scanning calorimeter (DSC), a method of pulverizing the liquid crystal polyester resin obtained by melting at a melt processing temperature below the end point on the high-temperature side of the endothermic peak indicating the melting temperature in a differential scanning calorimeter (DSC), a method of pulverizing pellet-shaped liquid crystal polyester resin, a method of pulverizing an oligomer of the liquid crystal polyester resin and then performing solid-phase polymerization, a method of pulverizing sheet-shaped liquid crystal polyester resin, a method of producing a sheet composed of a liquid crystal polyester resin and a non-liquid-crystalline thermoplastic resin and then eluting and removing the non-liquid-crystalline thermoplastic resin with a solvent, etc. can be mentioned. In addition to obtaining particles in a high yield, from the viewpoint of being able to control the oil absorption amount of the purified product to a suitable range and achieving stable tensile properties and dielectric properties, during the production of the liquid crystal polyester resin, a method of pulverizing the liquid crystal polyester resin discharged at a die temperature below the end point on the high-temperature side of the endothermic peak indicating the melting temperature in a differential scanning calorimeter (DSC), and a method of pulverizing the liquid crystal polyester resin obtained by melting at a melt processing temperature below the end point on the high-temperature side of the endothermic peak indicating the melting temperature in a differential scanning calorimeter (DSC) are preferred.

[0042] As a method for pulverizing the liquid crystal polyester resin, methods such as using a counter jet mill (manufactured by Hosokawa Micron Corporation), a mesh mill type pulverizer (manufactured by Horai Co., Ltd.), a masu colloid mill (manufactured by Masu Kogyo Co., Ltd.), a ball mill type cryogenic pulverizer (manufactured by Nippon Kogaku Kogyo Co., Ltd.), a freezer mill (manufactured by SPEX), etc. can be mentioned. From the viewpoint of being able to control the oil absorption amount of the purified product to a suitable range, it is preferable to pulverize by a method that applies a strong impact, such as a counter jet mill or a freezer mill.

[0043] The liquid crystal polyester resin particles of the present invention can be processed into molded articles having excellent surface appearance (color tone), mechanical properties, and heat resistance by molding methods such as ordinary injection molding, extrusion molding, press molding, solution cast film formation, and spinning. Examples of the molded articles herein include injection molded articles, extrusion molded articles, press molded articles, sheets, pipes, unstretched films, uniaxially stretched films, biaxially stretched films, and other various films, unstretched yarns, super stretched yarns, and other various fibers. From the viewpoint of significantly obtaining the effects of the liquid crystal polyester resin particles of the present invention, which result in stable tensile properties and dielectric properties, a film is preferred. Among them, it is preferably a film formed by applying a dispersion in which the liquid crystal polyester resin particles are dispersed in a dispersion medium onto a support and removing the dispersion medium. The method for manufacturing the film will be described later.

[0044] <dispersion> The liquid crystal polyester resin particles of the present invention can also be dispersed in at least one medium (A) selected from a thermosetting resin, a thermoplastic resin, and a dispersion medium to form a dispersion. The thermoplastic resin and the thermosetting resin are not particularly limited, and may be a liquid crystal polyester resin.

[0045] The thermosetting resin is not particularly limited, and examples thereof include epoxy resins, phenolic resins, polyimide resins, bismaleimide triazine resins (BT resins), and the like. The precursor before the thermosetting resin cures may be dissolved in the dispersion medium described later. Among them, from the viewpoint that the liquid crystal polyester resin particles of the present invention have good dispersibility in the dispersion medium and the resulting film has stable tensile properties and dielectric properties, a polyimide resin capable of adding liquid crystal polyester resin particles to a polyamic acid solution, which is a precursor, is preferred.

[0046] The epoxy resin is not particularly limited. For example, bisphenol-type epoxy resins such as bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, and bisphenol AD-type epoxy resin, naphthalene-type epoxy resin, glycidylamine-type epoxy resin, alicyclic epoxy resin, polyether-modified epoxy resin, silicone-modified epoxy resin, glycidyl ester-type epoxy resin, and other bifunctional epoxy resins can be mentioned. In addition, polyfunctional epoxy resins such as phenol novolac-type epoxy resin, biphenyl-type epoxy resin, naphthalene-type epoxy resin, dicyclopentadiene-type epoxy resin, xylylene-type epoxy resin, cresol novolac-type epoxy resin, and tetrakisphenol ethane-type epoxy resin can also be used. The epoxy resin may be used alone or in combination of two or more.

[0047] Examples of the phenol resin include, but are not limited to, cresol novolac-type phenol resin, phenol novolac resin, alkylphenol novolac resin, bisphenol A-type novolac resin, dicyclopentadiene-type phenol resin, zyloc-type phenol resin, terpene-modified phenol resin, polyvinylphenols, naphthol aralkyl-type phenol resin, biphenyl aralkyl-type phenol resin, naphthalene-type phenol resin, aminotriazine novolac-type phenol resin, etc. The phenol resin may be used alone or in combination of two or more.

[0048] As the bismaleimide triazine resin (BT resin), various bismaleimide triazine resins obtained by crosslinking bismaleimide and aromatic cyanate ester can be used. The bismaleimide triazine resin may be used alone or in combination of two or more.

[0049] As the polyimide resin, various polyimide resins obtained by using an acid anhydride and a diamine can be used. The acid anhydride is preferably an aromatic tetracarboxylic acid. For example, 3,3',4,4'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, etc. are exemplified. The diamine is preferably an aromatic diamine, and p-phenylenediamine, 4,4'-diaminodiphenyl ether, etc. are exemplified, but not limited thereto. Also, an imidization catalyst such as an amine compound and a dehydrating agent such as a carboxylic anhydride can be used in combination. When using a polyimide resin as the resin component, it is preferable to use a polyamic acid obtained by polymerizing an acid anhydride and a diamine and imidize it during or after molding. The polyimide resin may be used alone or in combination of two or more.

[0050] As a method for producing a polyimide resin containing the liquid crystal polyester resin particles of the present invention, from the viewpoint that the dispersibility of the liquid crystal polyester resin particles in the dispersion medium is good and the obtained film has stable tensile properties and dielectric properties, a method of adding to the polyamic acid solution which is a precursor is preferable.

[0051] Examples of the thermoplastic resin include, but are not limited to, liquid crystal polyester resin, polyphenylene sulfide resin, polyphenylene ether resin, polyamide resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polybutylene naphthalate resin, etc.

[0052] The thermosetting resin and the thermoplastic resin may be used alone or in combination of two or more. From the viewpoint of exhibiting the excellent dielectric properties of the liquid crystal polyester resin and achieving stable dielectric properties, the content of the liquid crystal polyester resin particles with respect to the total amount of the thermosetting resin or the thermoplastic resin and the liquid crystal polyester resin particles is preferably 1% by mass or more, more preferably 3% by weight or more, and even more preferably 5% by weight or more. On the other hand, the upper limit of the content of the liquid crystal polyester resin particles is not particularly limited. For example, if it is 99 parts by weight or less, the properties of the thermosetting resin and the thermoplastic resin can be imparted. Preferably it is 95% by weight or less, more preferably 90% by weight or less.

[0053] When the dispersion contains a dispersion medium, the above range is determined based on the weight of the resin excluding the dispersion medium.

[0054] The dispersion medium referred to in the present invention is not particularly limited as long as the liquid crystal polyester resin particles are insoluble therein. The dispersion medium is preferably a fluid, and more preferably a liquid. There may be a non-uniform portion in the distribution of the liquid crystal polyester resin particles in the dispersion. The dispersion medium may be in a state where nothing is dissolved, or may be in a state where a precursor of a thermosetting resin or a thermoplastic resin other than the liquid crystal polyester resin particles of the present invention is dissolved. The state of the liquid crystal polyester resin particles in the dispersion may be such that the dispersion can be applied onto a support in the method for producing a resin film described later.

[0055] Examples of the dispersion medium include halogenated hydrocarbons such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, 1-chlorobutane, chlorobenzene, o-dichlorobenzene; halogenated alcohols such as hexafluoroisopropanol; halogenated phenols such as p-chlorophenol, pentachlorophenol, pentafluorophenol; ethers such as diethyl ether, tetrahydrofuran, 1,4-dioxane; ketones such as acetone, cyclohexanone; esters such as ethyl acetate, γ-butyrolactone; amide compounds such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and urea compounds such as tetramethylurea; nitro compounds such as nitromethane, nitrobenzene; sulfur compounds such as dimethyl sulfoxide, sulfolane; and phosphorus compounds such as hexamethylphosphoric triamide, tri-n-butyl phosphate. Two or more of them may be used.

[0056] From the viewpoint of the dispersibility of liquid crystal polyester resin particles, an aprotic compound, particularly an aprotic compound having no halogen atom, is preferable as the dispersion medium. As the aprotic compound, it is preferable to use an amide such as N,N-dimethylformamide, N,N-dimethylacetamide, tetramethylurea, N-methylpyrrolidone or an ester such as γ-butyrolactone, and N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone are more preferable.

[0057] From the viewpoint of removability, a compound having a boiling point of 220°C or lower is preferable as the dispersion medium. From the perspective of the film thickness of the film obtained from the dispersion, the proportion of the liquid crystal polyester resin particles contained in the dispersion medium is preferably 0.1% by weight or more, more preferably 1% by weight or more, still more preferably 3% by weight or more, and particularly preferably 5% by weight or more with respect to the total amount of the liquid crystal polyester resin particles and the liquid. On the other hand, from the perspective of the dispersibility of the liquid crystal polyester resin particles, 60% by weight or less is preferable, 50% by weight or less is more preferable, 40% by weight or less is still more preferable, and 30% by weight or less is particularly preferable. When the dispersion medium is a solution in which a precursor of a thermosetting resin or a thermoplastic resin is dissolved, the weight obtained by subtracting the weight of the thermosetting resin or the thermoplastic resin from the weight of the solution is taken as the weight of the liquid.

[0058] Also, within a range not impairing the effects of the present invention, known fillers, additives, etc. may be contained in the dispersion of the present invention.

[0059] <Resin Film and Laminate> The liquid crystal polyester resin particles and the dispersion of the present invention can be used as raw materials for producing resin films and laminates.

[0060] The laminate of the present invention can be produced, for example, by the following methods (I) to (III).

[0061] (I) A method of applying a dispersion in which the liquid crystal polyester resin particles of the present invention are dispersed in a dispersion medium onto a support and removing the dispersion medium.

[0062] (II) A method of applying a dispersion in which the liquid crystal polyester resin particles of the present invention are dispersed in a dispersion medium onto a support, removing the dispersion medium, and then performing a heat treatment.

[0063] (III) A method of applying a dispersion in which the liquid crystal polyester resin particles of the present invention are dispersed in a liquid thermosetting resin precursor onto a support and performing a heat treatment.

[0064] From the viewpoint that the liquid crystal polyester resin particles of the present invention have good dispersibility in a dispersion medium and the resulting film has stable tensile properties and dielectric properties, the method of (I) or (II) above is preferable. Further, the resin film of the present invention can be produced, for example, by the following method (IV) or (V).

[0065] (IV) A method of press-molding the liquid crystal polyester resin particles of the present invention.

[0066] (V) A method of removing a support from a laminate obtained by any of the methods (I) to (III) above.

[0067] From the viewpoint that the liquid crystal polyester resin particles of the present invention have good dispersibility in a dispersion medium and the resulting film has stable tensile properties and dielectric properties, the method of (V) above is preferable. The support used in the methods (I) to (III) above is not particularly limited and is selected from, for example, metal foils, glass substrates, polymer films, and the like. In the support used in the methods (I) to (III), it is important to be resistant to the dispersion medium to be used. The support may be a single substance such as a metal foil, a glass substrate, or a polymer film, or a composite material thereof. Examples of the polymer film include an insulating polyimide film, a liquid crystal polyester film, a cycloolefin polymer film, and a polypropylene film.

[0068] Examples of the metal used when the support is a metal layer include gold, silver, copper, nickel, aluminum, and the like. Copper is preferable for circuit board applications such as flexible printed wiring boards and rigid printed wiring boards in electric and electronic parts and mechanical parts.

[0069] Hereinafter, a method for producing a laminate by the methods (I) and (II) above will be described. As a method of applying the liquid crystal polyester resin particles of the present invention dispersed in a dispersion medium onto a support, for example, various means such as a roller coating method, a dip coating method, a spray coater method, a spinner coating method, a curtain coating method, a slot coating method, a screen printing method, etc. can be mentioned. By these means, the dispersion is cast flat and uniformly onto the support to form a coating film.

[0070] Subsequently, by removing the dispersion medium in the coating film, a resin layer is formed on the surface of the support. The method of removing the dispersion medium is preferably carried out by evaporation of the liquid. Examples of the method of evaporating the dispersion medium include methods such as heating, reduced pressure, and ventilation. From the viewpoint of suppressing the rapid evaporation of the dispersion medium and obtaining a film with a uniform film thickness, it is preferable to remove the dispersion medium by heating. The heating temperature is not particularly limited as long as it is a temperature at which the dispersion medium volatilizes, but from the viewpoint of suppressing the rapid evaporation of the dispersion medium and obtaining a film with a uniform film thickness, it is preferably a temperature lower than the boiling point of the dispersion medium. Therefore, it is preferable to heat at a temperature higher than room temperature and lower than the boiling point of the dispersion medium.

[0071] After forming the laminate in this way, from the viewpoint of improving the dielectric properties and tensile properties, as in the method of (II) above, heat treatment may be further carried out as necessary. The method of heat treatment is not particularly limited and can be carried out using devices such as a hot air oven, a reduced pressure oven, a hot plate, etc. Also, the heat treatment may be carried out under atmospheric pressure, or under pressure or reduced pressure within a range where the support and the liquid crystal polyester resin particles do not deteriorate. The liquid crystal polyester resin particles may or may not melt by heat treatment. Also, from the viewpoint of suppressing the deterioration of the liquid crystal polyester resin particles, it is preferable to carry out the heat treatment in an atmosphere of an inert gas. For example, it can be carried out by raising the temperature from the range of the melting point of the liquid crystal polyester resin - 50°C to the melting point - 5°C to the range of the melting point + 5°C to the melting point + 50°C over 1 to 50 hours under a nitrogen gas flow.

[0072] Examples of the structure of the laminate thus obtained include a two-layer structure of a film and a support, a three-layer structure in which supports are laminated on both sides of the film, a three-layer structure in which films are laminated on both sides of the support, and a multilayer structure in which films and supports are alternately laminated in four or more layers.

[0073] The laminate thus obtained may be used as a resin film by removing the support as necessary, as in the method (V) above. The method for removing the support is not particularly limited. However, when the support is a metal foil such as a copper foil, it can be removed using a ferric chloride solution.

[0074] The laminate and resin film obtained by the above method can be used, for example, in electric and electronic parts represented by various computers, office automation equipment, audio-visual equipment, etc., circuit boards such as flexible printed wiring boards and rigid printed wiring boards on which electric and electronic parts are mounted; semiconductor packages used for in-vehicle semiconductors, industrial semiconductors, etc.; substrates for transparent conductive films, substrates for polarizing films, packaging films for various processed foods and microwave heating, electromagnetic wave shielding films, antibacterial films, gas separation films, etc. Since a laminate having stable tensile properties and dielectric properties can be easily obtained, it is preferably used in circuit boards such as flexible printed wiring boards and rigid printed wiring boards in electric and electronic parts and mechanical parts, and semiconductor packages using the laminate.

Examples

[0075] Hereinafter, the present invention will be described using examples, but the present invention is not limited by the examples. In the production examples, the composition and property evaluation of the liquid crystal polyester resin were measured by the following methods.

[0076] (1) Composition analysis of liquid crystal polyester resin To 0.1 mg of pulverized liquid crystal polyester resin pellets, 2 μL of a 25% methanol solution of tetramethylammonium hydroxide was added, and pyrolysis GC / MS measurement was performed using Shimadzu GCMS-QP5050A to determine the composition ratio of each constituent component in the liquid crystal polyester resin.

[0077] (2) Measurement of the melting point (Tm) of liquid crystal polyester Using a differential scanning calorimeter DSC-7 (manufactured by PerkinElmer), after observing the endothermic peak temperature (Tm1) when heating the liquid crystal polyester resin from room temperature under a temperature increase condition of 20 °C / min, holding it at a temperature of Tm1 + 20 °C for 5 minutes, then once cooling it to room temperature under a temperature decrease condition of 20 °C / min, and heating it again under a temperature increase condition of 20 °C / min, the endothermic peak temperature observed was taken as the melting point (Tm).

[0078] (3) Melt viscosity of liquid crystal polyester resin Using a Koka type flow tester CFT-500D (orifice 0.5φ × 10 mm) (manufactured by Shimadzu Corporation), the melt viscosity of the liquid crystal polyester resin was measured at Tm + 10 °C, or at 280 °C when Tm is less than 270 °C, under the condition of a shear rate of 1000 / s.

[0079] (4) Measurement of the absolute number average molecular weight of liquid crystal polyester resin The absolute number average molecular weight of the liquid crystal polyester resin was measured and determined by the gel permeation chromatography (GPC) / LALLS method shown under the following conditions.

[0080] (GPC) GPC apparatus: Manufactured by Waters Detector: Differential refractive index detector RI2410 (manufactured by Waters) Columns: Shodex K-806M (2 pieces), K-802 (1 piece) (manufactured by Showa Denko) Eluent: Pentafluorophenol / chloroform (35 / 65 w / w%) Measurement temperature: 23 °C Flow rate: 0.8 mL / min Sample injection volume: 200 μL (concentration: 0.1%).

[0081] (LALLS) Apparatus: Low angle laser light scattering photometer KMX-6 (manufactured by Chromatix) Detector wavelength: 633 nm (He-Ne) Detector temperature: 23 °C.

[0082] <Production of Liquid Crystal Polyester Resin (A)> [Production Example 1] Into a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 25 parts by weight of p-hydroxybenzoic acid, 1355 parts by weight of 6-hydroxy-2-naphthoic acid, 184 parts by weight of 4,4'-dihydroxybiphenyl, 164 parts by weight of isophthalic acid, 121 parts by weight of polyethylene terephthalate having an intrinsic viscosity of about 0.6 dl / g, and 1070 parts by weight of acetic anhydride (1.12 equivalents in total of phenolic hydroxyl groups) were charged, and an acetylation reaction was carried out at 145°C for 180 minutes while stirring under a nitrogen gas atmosphere. Then, the temperature was raised from 145°C to 300°C over 4 hours. Thereafter, the polymerization temperature was maintained at 300°C, the pressure was reduced to 1.0 mmHg (133 Pa) over 1.0 hour, and the reaction was further continued. Polymerization was completed when the torque required for stirring reached 40 kg·cm. Next, the inside of the reaction vessel was pressurized to 2.0 kg / cm 2 (0.2 MPa), and the polymer was discharged in a strand form through a die (285°C) having one circular discharge port with a diameter of 10 mm and pelletized with a cutter to obtain a liquid crystal polyester resin (A-1).

[0083] When the composition analysis was performed on this liquid crystal polyester resin (A-1), the structural unit derived from p-hydroxybenzoic acid was 1.7 mol%, the structural unit derived from 6-hydroxy-2-naphthoic acid was 67.8 mol%, the structural unit derived from 4,4'-dihydroxybiphenyl was 9.3 mol%, the structural unit derived from terephthalic acid was 5.9 mol%, the structural unit derived from isophthalic acid was 9.3 mol%, and the structural unit derived from ethylene glycol was 5.9 mol%. Also, Tm was 285°C and the melt viscosity was 50 Pa·s.

[0084] [Production Example 2] Into a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 25 parts by weight of p-hydroxybenzoic acid, 1355 parts by weight of 6-hydroxy-2-naphthoic acid, 184 parts by weight of 4,4'-dihydroxybiphenyl, 164 parts by weight of isophthalic acid, 121 parts by weight of polyethylene terephthalate having an intrinsic viscosity of about 0.6 dl / g, and 1032 parts by weight of acetic anhydride (1.08 equivalents in total of phenolic hydroxyl groups) were charged, and the acetylation reaction was carried out at 145 °C for 120 minutes while stirring in a nitrogen gas atmosphere. Then, the temperature was raised from 145 °C to 300 °C over 4 hours. Thereafter, the polymerization temperature was maintained at 300 °C, the pressure was reduced to 1.0 mmHg (133 Pa) over 1.0 hour, and the reaction was further continued. Polymerization was completed when the torque required for stirring reached 10 kg·cm. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm 2 (0.1 MPa), and the polymer was discharged in a strand form through a die (280 °C) having one circular discharge port with a diameter of 10 mm and pelletized with a cutter to obtain a liquid crystal polyester resin (A-2).

[0085] When the composition analysis was performed on this liquid crystal polyester resin (A-2), the structural unit derived from p-hydroxybenzoic acid was 1.7 mol%, the structural unit derived from 6-hydroxy-2-naphthoic acid was 67.8 mol%, the structural unit derived from 4,4'-dihydroxybiphenyl was 9.3 mol%, the structural unit derived from terephthalic acid was 5.9 mol%, the structural unit derived from isophthalic acid was 9.3 mol%, and the structural unit derived from ethylene glycol was 5.9 mol%. Also, Tm was 280 °C and the melt viscosity was 10 Pa·s.

[0086] [Production Example 3] 870 parts by weight of p-hydroxybenzoic acid, 352 parts by weight of 4,4'-dihydroxybiphenyl, 89 parts by weight of hydroquinone, 292 parts by weight of terephthalic acid, 157 parts by weight of isophthalic acid and 1338 parts by weight of acetic anhydride (1.12 equivalents in total of phenolic hydroxyl groups) were charged into a 5 L reaction vessel equipped with a stirring blade and a bleed pipe, and the mixture was reacted at 145°C for 130 minutes while stirring in a nitrogen gas atmosphere. Then, the temperature was raised from 145°C to 330°C over 4 hours. Thereafter, the polymerization temperature was maintained at 330°C, the pressure was reduced to 1.0 mmHg (133 Pa) over 1.0 hour, and the reaction was further continued. Polymerization was completed when the torque required for stirring reached 20 kg·cm. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm 2 (0.1 MPa), and the polymer was discharged in a strand form through a die (310°C) having one circular discharge port with a diameter of 10 mm, and pelletized with a cutter to obtain a liquid crystal polyester resin (A-3).

[0087] When the liquid crystal polyester resin (A-3) was subjected to compositional analysis, the structural unit derived from p-hydroxybenzoic acid was 53.8 mol%, the structural unit derived from 4,4'-dihydroxybiphenyl was 16.2 mol%, the structural unit derived from hydroquinone was 6.9 mol%, the structural unit derived from terephthalic acid was 15.0 mol%, and the structural unit derived from isophthalic acid was 8.1 mol%. Also, Tm was 310°C and the melt viscosity was 30 Pa·s.

[0088] [Production Example 4] The pellets of the liquid crystal polyester resin (A-3) obtained in Production Example 3 were filled in a SUS tray and heat-treated at 265°C for 30 hours under a nitrogen stream to obtain a liquid crystal polyester resin (A-4).

[0089] [Production Example 5] Into a 5 L reaction vessel equipped with a stirring blade and a bleed pipe, 746 parts by weight of p-hydroxybenzoic acid, 85 parts by weight of 6-hydroxy-2-naphthoic acid, 206 parts by weight of 4,4'-dihydroxybiphenyl, 265 parts by weight of terephthalic acid, 49 parts by weight of p-aminophenol, and 956 parts by weight of acetic anhydride (1.10 equivalents based on the total phenolic hydroxyl groups) were charged, and the mixture was reacted at 145 °C for 120 minutes with stirring under a nitrogen gas atmosphere, and then the temperature was raised from 145 °C to 360 °C over 4 hours. Then, the polymerization temperature was maintained at 360 °C, the pressure was reduced to 1.0 mmHg (133 Pa) over 1.0 hour, and the reaction was further continued. Polymerization was completed when the torque required for stirring reached 20 kg·cm. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm 2 (0.1 MPa), and the polymer was discharged in a strand form through a die (337 °C) having one circular discharge port with a diameter of 10 mm and pelletized by a cutter to obtain a liquid crystal polyester resin (A-6).

[0090] When the composition analysis was performed on this liquid crystal polyester resin (A-6), the structural unit derived from p-hydroxybenzoic acid was 60.0 mol%, the structural unit derived from 6-hydroxy-2-naphthoic acid was 5.0 mol%, the structural unit derived from 4,4'-dihydroxybiphenyl was 12.3 mol%, the structural unit derived from terephthalic acid was 17.7 mol%, and the structural unit derived from p-aminophenol was 5.0 mol%. Also, Tm was 337 °C and the melt viscosity was 30 Pa·s. Table 1 shows the results of the evaluations (1) and (4) for the pellets obtained in Production Examples 1 to 5.

[0091]

Table 1

[0092] <Production of Thermoplastic Resin (B)> [Production Example 6] 5 L reaction vessel equipped with a stirring blade and a bleed pipe was charged with 528 parts by weight of p-hydroxybenzoic acid, 126 parts by weight of 4,4'-dihydroxybiphenyl, 112 parts by weight of terephthalic acid, 865 parts by weight of polyethylene terephthalate with an intrinsic viscosity of about 0.6 dl / g, and 581 parts by weight of acetic anhydride (1.10 equivalents in total of phenolic hydroxyl groups). The mixture was reacted at 145 °C for 90 minutes while stirring under a nitrogen gas atmosphere, and then the temperature was raised from 145 °C to 290 °C over 4 hours. Thereafter, the polymerization temperature was maintained at 290 °C, the pressure was reduced to 1.0 mmHg (133 Pa) in 1.0 hour, and the reaction was continued. Polymerization was completed when the torque required for stirring reached 20 kg·cm. Next, the inside of the reaction vessel was pressurized to 1.0 kg / cm 2 (0.1 MPa), and the polymer was discharged as a strand through a die having one circular discharge port with a diameter of 10 mm and pelletized by a cutter to obtain a thermoplastic resin (B-1). The thermoplastic resin (B-1) was a liquid crystal polyester resin that formed an anisotropic molten phase.

[0093] When the composition analysis was performed on this thermoplastic resin (B-1), the structural unit derived from p-hydroxybenzoic acid was 27.0 mol%, the structural unit derived from 4,4'-dihydroxybiphenyl was 4.8 mol%, the structural unit derived from terephthalic acid was 36.5 mol%, and the structural unit derived from ethylene glycol was 31.7 mol%. Also, Tm was 210 °C and the melt viscosity was 20 Pa·s.

[0094] <Production of thermoplastic resin solution (C)> [Production Example 7] 35 parts by weight of the thermoplastic resin (B-1) was added to 425 parts by weight of hexafluoroisopropanol and heated at 50 °C for 3 hours to obtain a brown transparent thermoplastic resin solution (C-1).

[0095] <Production of polyamic acid solution (C)> [Production Example 8] After purging a 1 L container equipped with a nitrogen inlet tube, a thermometer, and a stir bar with nitrogen, 25 parts by weight of 4,4'-diaminodiphenyl ether was charged. Next, 520 parts by weight of N-methyl-2-pyrrolidone was added and completely dissolved, then 27.2 parts by weight of pyromellitic dianhydride was added, and the mixture was stirred at a reaction temperature of 25 °C for 15 hours to obtain a brown, viscous polyamic acid solution (C-2) (polyamic acid concentration: 10 wt%).

[0096] <Examples 1 to 5, Comparative Examples 1 to 3> In the examples, the volume average particle diameter and the oil absorption of the purified tallow of the liquid crystal polyester resin particles were measured by the following methods.

[0097] (4) Volume average particle diameter The liquid crystal polyester resin particles dispersed in pure water were measured for the cumulative particle size distribution based on volume of the liquid crystal polyester resin particles using a particle size distribution analyzer Microtrac MT3300EXII (manufactured by Nikkiso Co., Ltd.) by the laser diffraction / light scattering method, assuming the refractive index of pure water to be 1.333, and the average particle diameter (D 50 ) was calculated.

[0098] (5) Oil absorption of purified tallow In accordance with Japanese Industrial Standard (JIS standard) JIS K 5101 (2004) "Pigment test method - Purified tallow method", approximately 100 mg of the liquid crystal polyester resin particles were precisely weighed on a watch glass, and purified tallow (manufactured by Kanto Chemical Co., Inc.) was gradually added drop by drop with a burette. After kneading with a palette knife, the dropping-kneading was repeated until a lump of the sample was formed, and the point at which the paste reached a smooth hardness was taken as the end point. The oil absorption (mL / 100 g) was calculated from the amount of purified tallow used for dropping.

[0099] [Example 1] Regarding the pellets of liquid crystal polyester resin (A-1), after coarsely pulverizing using an Oster blender, a freezer mill (manufactured by SPEX) was used. With a pulverization time of 1 minute and 30 seconds, a RATE of 15 CPS, and a cooling time of 1 minute as one cycle, cryogenic pulverization was performed 5 cycles under liquid nitrogen to obtain liquid crystal polyester resin particles with a volume average particle diameter of 8 μm and an oil absorption of 65 mL / 100 g for purified linseed oil. 8 parts by weight of the obtained liquid crystal polyester resin particles were added to 92 parts by weight of N-methyl-2-pyrrolidone (D-1), and stirred using a homogenizer (manufactured by IKA) to obtain a dispersion.

[0100] The dispersion was applied to the roughened surface of the copper foil using a film applicator and an automatic coating device (manufactured by BEVS) so that the thickness of the cast film was 500 μm, and dried at 40 °C for 4 hours to remove the dispersion medium. Then, a heat treatment was performed by holding in a hot air oven at 310 °C for 6 hours under a nitrogen atmosphere to obtain a liquid crystal polyester resin film with a copper foil having a length of 300 mm × a width of 210 mm.

[0101] [Example 2] Regarding the pellets of liquid crystal polyester resin (A-1), pulverization was performed in the same manner as in Example 1 to obtain liquid crystal polyester resin particles with a volume average particle diameter of 8 μm and an oil absorption of 65 mL / 100 g for purified linseed oil. 8 parts by weight of the obtained liquid crystal polyester resin particles were added to 92 parts by weight of the thermoplastic resin solution (C-1), and stirred using a homogenizer (manufactured by IKA) to obtain a dispersion. The dispersion was applied to the roughened surface of the copper foil using a film applicator and an automatic coating device (manufactured by BEVS) so that the thickness of the cast film was 500 μm, and dried at 25 °C for 1 hour to remove the dispersion medium. Then, a heat treatment was performed by holding in a hot air oven at 310 °C for 6 hours under a nitrogen atmosphere to obtain a resin film with a copper foil having a length of 300 mm × a width of 210 mm.

[0102] [Example 3] The pellets of liquid crystal polyester resin (A-1) were pulverized in the same manner as in Example 1 to obtain liquid crystal polyester resin particles having a volume average particle diameter of 8 μm and an oil absorption of 65 mL / 100 g of purified waste. 8 parts by weight of the obtained liquid crystal polyester resin particles were added to 92 parts by weight of a polyamic acid solution (C-2), and stirred using a homogenizer (manufactured by IKA) to obtain a dispersion. The dispersion was applied to the roughened surface of a copper foil using a film applicator and an automatic coating device (manufactured by BEVS) so that the thickness of the cast film was 500 μm, and dried at 40°C for 4 hours to remove the dispersion medium. Thereafter, a heat treatment was further performed by holding in a hot air oven at 350°C for 6 hours in a nitrogen atmosphere to advance the imidization reaction, and a resin film with a copper foil having a length of 300 mm × a width of 210 mm was obtained.

[0103] [Example 4] Pulverization was carried out in the same manner as in Example 1 except that pellets of liquid crystal polyester resin (A-4) were used, and liquid crystal polyester resin particles having a volume average particle diameter of 24 μm and an oil absorption of 275 mL / 100 g of purified waste were obtained. 8 parts by weight of the obtained liquid crystal polyester resin particles were added to 92 parts by weight of N-methyl-2-pyrrolidone (D-1), and stirred using a homogenizer (manufactured by IKA) to obtain a dispersion. The dispersion was applied to the roughened surface of a copper foil using a film applicator and an automatic coating device (manufactured by BEVS) so that the thickness of the cast film was 500 μm, and dried at 40°C for 4 hours to remove the dispersion medium. Thereafter, a heat treatment was further performed by holding in a hot air oven at 350°C for 6 hours in a nitrogen atmosphere to obtain a liquid crystal polyester resin film with a copper foil having a length of 300 mm × a width of 210 mm.

[0104] [Example 5] Pulverization of the pellets of liquid crystal polyester resin (A-1) was carried out in the same manner as in Example 1 except that the freeze pulverization was set as 1 cycle, and liquid crystal polyester resin particles having a volume average particle diameter of 36 μm and an oil absorption of 146 mL / 100 g of purified waste were obtained. 8 parts by weight of the obtained liquid crystal polyester resin particles were added to 92 parts by weight of N-methyl-2-pyrrolidone (D-1), and stirred using a homogenizer (manufactured by IKA) to obtain a dispersion. The dispersion was applied to the roughened surface of the copper foil using a film applicator and an automatic coating device (manufactured by BEVS) so that the thickness of the cast film was 500 μm, and after removing the dispersion medium by drying at 40 °C for 4 hours, a heat treatment was further performed by holding it in a hot air oven at 310 °C for 6 hours in a nitrogen atmosphere to obtain a liquid crystal polyester resin film with a copper foil having a length of 300 mm × a width of 210 mm.

[0105] [Comparative Example 1] The liquid crystal polyester resin (A-2) was used as pellets, and pulverization was carried out in the same manner as in Example 1 except that freeze pulverization was carried out for 4 cycles to obtain liquid crystal polyester resin particles having a volume average particle diameter of 10 μm and an oil absorption of 313 mL / 100 g for purified linseed oil. 8 parts by weight of the obtained liquid crystal polyester resin particles were added to 92 parts by weight of N-methyl-2-pyrrolidone (D-1), and stirred using a homogenizer (manufactured by IKA) to obtain a dispersion. The dispersion was applied to the roughened surface of the copper foil using a film applicator and an automatic coating device (manufactured by BEVS) so that the thickness of the cast film was 500 μm, and after removing the dispersion medium by drying at 40 °C for 4 hours, a heat treatment was further performed by holding it in a hot air oven at 310 °C for 6 hours in a nitrogen atmosphere to obtain a liquid crystal polyester resin film with a copper foil having a length of 300 mm × a width of 210 mm.

[0106] [Comparative Example 2] Pulverization was carried out in the same manner as in Example 1 except that the liquid crystal polyester resin (A-3) was used as pellets, and liquid crystal polyester resin particles having a volume average particle diameter of 15 μm and an oil absorption of 355 mL / 100 g for purified linseed oil were obtained. 8 parts by weight of the obtained liquid crystal polyester resin particles were added to 92 parts by weight of N-methyl-2-pyrrolidone (D-1), and stirred using a homogenizer (manufactured by IKA) to obtain a dispersion.

[0107] The dispersion was applied to the roughened surface of the copper foil using a film applicator and an automatic coating device (manufactured by BEVS) so that the thickness of the cast film was 500 μm, and after drying at 40°C for 4 hours to remove the dispersion medium, a heat treatment was further performed by holding it in a hot air oven at 350°C for 6 hours under a nitrogen atmosphere to obtain a liquid crystal polyester resin film with a copper foil of 300 mm in length × 210 mm in width.

[0108] [Comparative Example 3] The pellets of the liquid crystal polyester resin (A-1) were roughly pulverized using an Oster blender, then sieved through a sieve with an opening of 100 μm to obtain liquid crystal polyester resin particles with a volume average particle diameter of 60 μm passing through the sieve and an oil absorption of 303 mL / 100 g of purified linseed oil. 8 parts by weight of the obtained liquid crystal polyester resin particles were added to 92 parts by weight of N-methyl-2-pyrrolidone (D-1), and stirred using a homogenizer (manufactured by IKA) to obtain a dispersion. The dispersion was applied to the roughened surface of the copper foil using a film applicator and an automatic coating device (manufactured by BEVS) so that the thickness of the cast film was 500 μm, and after drying at 40°C for 4 hours to remove the dispersion medium, a heat treatment was further performed by holding it in a hot air oven at 310°C for 6 hours under a nitrogen atmosphere to obtain a liquid crystal polyester resin film with a copper foil of 300 mm in length × 210 mm in width.

[0109] [Comparative Example 4] Pulverization was performed in the same manner as in Example 1 except that the pellets of the liquid crystal polyester resin (A-5) were used, and liquid crystal polyester resin particles with a volume average particle diameter of 17 μm and an oil absorption of 318 mL / 100 g of purified linseed oil were obtained. 8 parts by weight of the obtained liquid crystal polyester resin particles were added to 92 parts by weight of N-methyl-2-pyrrolidone (D-1), and stirred using a homogenizer (manufactured by IKA) to obtain a dispersion.

[0110] The dispersion was applied to the roughened surface of the copper foil using a film applicator and an automatic coating device (manufactured by BEVS) so that the thickness of the cast film would be 500 μm, and after drying at 40°C for 4 hours to remove the dispersion medium, a heat treatment was further performed by holding it in a hot air oven at 360°C for 6 hours under a nitrogen atmosphere, obtaining a liquid crystal polyester resin film with a copper foil having a length of 300 mm × a width of 210 mm.

[0111] Regarding the liquid crystal polyester resin films or resin films with copper foils obtained in Examples 1 to 5 and Comparative Examples 1 to 4, the copper foils were removed using a ferric chloride solution to obtain liquid crystal polyester resin films or resin films. Table 2 shows the results of the evaluations in the following (6) to (8).

[0112]

Table 2

[0113] (6) Film thickness For each liquid crystal polyester resin film or resin film, 15 locations were arbitrarily selected, and the thicknesses at these 15 locations were measured with a micrometer, and the average was calculated and taken as the film thickness.

[0114] (7) Dielectric property stability For each liquid crystal polyester resin film or resin film, 30 evaluation samples with a length of 45 mm × a width of 2.7 mm were produced. Then, the dielectric tangent at 23°C and 10 GHz was obtained by the cavity resonator perturbation method using a network analyzer N5230A manufactured by Agilent Technologies, Inc. and a cavity resonator CP531 manufactured by Kanto Electronics Co., Ltd., and the standard deviation of the dielectric tangents measured for 30 samples was calculated. The lower the standard deviation of the dielectric tangent, the smaller the variation and the better the dielectric property stability.

[0115] (8) Tensile property stability For each liquid crystal polyester resin film or resin film, 30 specimens of No. 3 dumbbell for tensile test with a parallel part width of 5 mm and a length of 20 mm were cut out based on JIS K6251 (2010), and a tensile test was conducted at a tensile speed of 5 mm / min in accordance with JIS K7161 (2014) to obtain the tensile strength (MPa). The standard deviation of the tensile strength measured for 30 specimens was calculated. The lower the standard deviation of the tensile strength, the smaller the variation and the better the stability of the tensile properties.

[0116] From the results in Table 2, by using liquid crystal polyester resin particles with a volume average particle diameter and an oil absorption amount of purified linseed oil within a predetermined range, a film having stable tensile properties and dielectric properties can be obtained.

Industrial Applicability

[0117] The liquid crystal polyester resin particles of the present invention have stable tensile properties and dielectric properties when formed into a film. The resin film and laminate obtained by using the liquid crystal polyester resin particles of the present invention are suitable for use in circuit boards such as flexible printed wiring boards and rigid printed wiring boards using a laminate characterized by laminating a plurality of sheets, and semiconductor packages.

Claims

1. Liquid crystal polyester resin particles, wherein the number average molecular weight of the liquid crystal polyester resin constituting the liquid crystal polyester resin particles is 12,000 or more, the volume average particle diameter is 0.1 to 50 μm, and the oil absorption amount of the purified waste oil calculated according to JIS K 5101 (2004) is 10 to 300 mL / 100 g.

2. The liquid crystal polyester resin particles according to claim 1, wherein the liquid crystal polyester resin constituting the liquid crystal polyester resin particles is a liquid crystal polyester resin containing 30 to 72 mol% of the following structural unit (I) with respect to 100 mol% of all the structural units of the liquid crystal polyester resin. 【Chemical 1】 (X and Y each independently represent an oxygen atom or a carbonyl group.)

3. The liquid crystal polyester resin particles according to claim 1 or 2, wherein the liquid crystal polyester resin constituting the liquid crystal polyester resin particles is a liquid crystal polyester resin containing 3 mol% or less of the following structural unit (II) with respect to 100 mol% of all the structural units of the liquid crystal polyester resin. -Z-Ar-NH- (II) (Ar represents a naphthalenediyl group or a phenylene group, and the hydrogen atoms in the naphthalenediyl group or phenylene group may each independently be substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. Z represents O, C=O, or NH.)

4. A dispersion in which the liquid crystal polyester resin particles according to any one of claims 1 to 3 are dispersed in at least one medium (A) selected from a thermosetting resin, a thermoplastic resin, and a dispersion medium.

5. The dispersion according to claim 4, wherein the medium (A) is a solvent in which a precursor of a thermosetting resin or a thermoplastic resin is dissolved.

6. A method for producing a laminate, comprising applying the dispersion according to claim 4 or 5 onto a support, and performing liquid removal and / or heat treatment to obtain a laminate.

7. A method for producing a resin film, comprising removing the support from the laminate obtained by the production method according to claim 6 to obtain a resin film.

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