阅读说明：本技术 液晶聚酯树脂组合物和成型体 (Liquid crystal polyester resin composition and molded article ) 是由 原节幸 于 2018-06-27 设计创作，主要内容包括：本发明的液晶聚酯树脂组合物,包含：液晶聚酯树脂；及填料,由纤维状填料和板状填料构成,相对于液晶聚酯树脂100质量份,所述填料的含量为15质量份以上且55质量份以下,纤维状填料的数均纤维长度为450μm以上且700μm以下。(The liquid crystal polyester resin composition of the present invention comprises: a liquid crystal polyester resin; and a filler composed of a fibrous filler and a plate-like filler, wherein the filler is contained in an amount of 15 to 55 parts by mass per 100 parts by mass of the liquid crystal polyester resin, and the number-average fiber length of the fibrous filler is 450 to 700 [ mu ] m.)

1. A liquid crystal polyester resin composition, wherein,

comprises the following steps: a liquid crystal polyester resin; and a filler composed of a fibrous filler and a plate-like filler,

the content of the filler is 15 parts by mass or more and 55 parts by mass or less with respect to 100 parts by mass of the liquid-crystalline polyester resin,

the number-average fiber length of the fibrous filler is 450 to 700 [ mu ] m.

2. The liquid-crystalline polyester resin composition according to claim 1,

the deflection temperature under load measured under a load of 1.82MPa is 260 ℃ or more and less than 285 ℃ for a test piece molded from the liquid crystal polyester resin composition according to ASTM D648.

3. The liquid-crystalline polyester resin composition according to claim 1 or 2,

the rockwell hardness of a test piece molded from the liquid crystal polyester resin composition is 108 or more and 115 or less as measured using an R scale according to ASTM D785.

4. A liquid-crystalline polyester resin composition according to any one of claims 1 to 3,

the content of the filler is 24 parts by mass or more and 45 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester resin.

5. The liquid-crystalline polyester resin composition according to any one of claims 1 to 4,

the ratio W1/W2 of the mass W1 contained in the fibrous filler to the mass W2 contained in the plate-like filler is 0.5 to 2.0.

6. The liquid-crystalline polyester resin composition according to any one of claims 1 to 5,

the plate-like filler has a volume average particle diameter of 5 to 50 [ mu ] m.

7. The liquid-crystalline polyester resin composition according to any one of claims 1 to 6,

the liquid crystal polyester resin is a mixture of a plurality of liquid crystal polyester resins having different flow initiation temperatures,

among the plurality of liquid crystal polyester resins, the first liquid crystal polyester resin having the highest flow initiation temperature has a flow initiation temperature of 300 ℃ to 400 ℃ inclusive, and the second liquid crystal polyester resin having the lowest flow initiation temperature has a flow initiation temperature of 260 ℃ to 350 ℃ inclusive.

8. A molded article, wherein,

a liquid-crystalline polyester resin composition according to any one of claims 1 to 7.

Technical Field

The present invention relates to a liquid crystal polyester resin composition and a molded article.

The present application claims priority based on japanese patent application No. 2017-131309, filed on japanese application at 7/4/2017, and the contents thereof are incorporated in the present application.

Background

The liquid crystal polyester resin has excellent moldability and high heat resistance. The liquid crystal polyester resin is mainly used for electronic parts such as connectors, relays, and bobbins by utilizing these characteristics. In recent years, electronic components have been advanced to high integration, miniaturization, thinning, and among them, the trend of miniaturization and thinning is remarkable in connector components.

Typical examples of such a thinned connector include a Board-to-Board (Board-to-Board) connector for bonding printed circuit boards to each other, and an FPC connector for connecting a flexible printed circuit Board (FPC) or a Flexible Flat Cable (FFC) to a printed circuit Board.

With the miniaturization of electronic devices using printed circuit boards, Board-to-Board (Board to Board) connectors and FPC connectors are required to be miniaturized. For example, a narrow pitch connector is provided in which the pitch between metal terminals of the connector is set to 0.35mm to 0.4 mm. Further, a thin connector having a height (so-called stacking height) of 0.6mm to 1.0mm in a state where the connector is fitted is provided.

However, if the connector is required to be compact and thin, insufficient filling due to insufficient resin fluidity may occur during molding of the connector. Therefore, further improvement in the fluidity of the resin in the sheet portion of the molded article (sheet fluidity) is required.

Further, if the connector is required to be compact and thin, the strength of the connector may be weakened by the thin thickness, and the practical strength may not be maintained. Specifically, the possibility that the connector is deformed by an impact at the time of transportation and use of the connector becomes high.

Similarly, the reduction in the rigidity of the connector due to the thinning may cause breakage when the connector is used. As an example of the breakage generated when the connector is used, crushing of the connector due to positional displacement when the connector is fitted is cited. Therefore, improvement in the rigidity of the connector is required.

Further, if the connector is intended to be downsized and thinned, the following phenomenon may occur even with a small warpage. For example, if warpage occurs in the connector, a gap is generated between the metal terminal and a circuit formed on the substrate. Therefore, the solder melted at the time of soldering may not remain in a sufficient amount in the gap between the metal terminal and the substrate, and the solder may solidify in a state where the metal terminal is separated from the circuit. As a result, the metal terminal and the circuit cannot be electrically connected, and a bonding failure may occur.

Therefore, a material for forming a sheet connector, such as a Board-to-Board (Board-to-Board) connector and a connector for FPC, is required to be capable of producing a molded product having excellent sheet fluidity, high strength, high hardness and low warpage. In the present embodiment, "low warpage" means that the warpage of the molded article obtained based on the least square plane of the molded article is small.

In response to such a demand, patent document 1 discloses a liquid crystal polyester resin composition having excellent fluidity and high weld strength. The liquid crystal polyester resin composition disclosed in patent document 1 comprises 98 to 20 mass% of a liquid crystal polyester, 1 to 79 mass% of a plate-like or granular filler, and 1 to 79 mass% of a glass fiber. The liquid crystal polyester used has a heat distortion temperature of 190 to 280 ℃, a liquid crystal onset temperature of 330 ℃ or lower, and a melt viscosity of 10000 poises or lower, and forms an anisotropic melt phase.

Disclosure of Invention

Problems to be solved by the invention

In the prior art described in patent document 1, studies have been made for the purpose of improving the mechanical strength, particularly the weld strength, of a liquid crystal polyester resin composition, but no studies have been made focusing on hardness. In patent document 1, the amount of filler to be blended is generally reduced in order to obtain excellent fluidity, and if this is taken into consideration, the hardness of the molded article is not necessarily sufficient.

As described above, various studies have been made on liquid crystal polyester resin compositions used for small and thin connectors, but the conventionally known techniques are insufficient, and further improvement is required.

In addition, it is expected that the same problem occurs not only in a compact molded body.

The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid crystal polyester resin composition capable of producing a molded article having excellent sheet fluidity, small warpage and high hardness. Further, it is an object of the present invention to provide a molded article having a small warpage and a high hardness, which is molded from the liquid crystal polyester resin composition.

Technical scheme for solving problems

In order to solve the above problems, one aspect of the present invention provides a liquid crystal polyester resin composition comprising 15 parts by mass or more and 55 parts by mass or less of a filler composed of a fibrous filler and a plate-like filler, based on 100 parts by mass of a liquid crystal polyester resin, wherein the number average fiber length of the fibrous filler is 450 μm or more and 700 μm or less.

In one embodiment of the present invention, the deflection temperature under load measured under a load of 1.82MPa may be 260 ℃ or more and less than 285 ℃ for a test piece molded from the liquid crystal polyester resin composition according to ASTM D648.

In one embodiment of the present invention, the rockwell hardness of a test piece molded from the liquid crystal polyester resin composition may be 108 or more and 115 or less as measured using an R scale in accordance with ASTM D785.

In one embodiment of the present invention, the liquid crystal polyester resin composition contains 24 parts by mass or more and 45 parts by mass or less of a filler per 100 parts by mass of the liquid crystal polyester resin, and the ratio (W1/W2) of the content (W1) of the fibrous filler to the content (W2) of the plate-like filler may be 0.5 or more and 2.0 or less.

In one embodiment of the present invention, the volume average particle diameter of the plate-like filler may be 5 μm or more and 50 μm or less.

In one embodiment of the present invention, the liquid crystal polyester resin is a mixture of a plurality of liquid crystal polyester resins having different flow starting temperatures, and among the plurality of liquid crystal polyester resins, the flow starting temperature of the first liquid crystal polyester resin having the highest flow starting temperature may be 300 ℃ to 400 ℃ inclusive, and the flow starting temperature of the second liquid crystal polyester resin having the lowest flow starting temperature may be 260 ℃ to 350 ℃ inclusive.

An aspect of the present invention provides a molded article comprising the liquid crystal polyester resin composition as a molding material.

Other embodiments of the present invention include the following embodiments.

[1] A liquid crystal polyester resin composition, wherein,

comprises the following steps: a liquid crystal polyester resin; and a filler composed of a fibrous filler and a plate-like filler, wherein the filler is contained in an amount of 15 to 55 parts by mass per 100 parts by mass of the liquid crystal polyester resin, and the number-average fiber length of the fibrous filler is 450 to 700 [ mu ] m.

[2] The liquid-crystalline polyester resin composition according to [1], wherein,

the deflection temperature under load measured under a load of 1.82MPa is 260 ℃ or more and less than 285 ℃ for a test piece molded from the liquid crystal polyester resin composition according to ASTM D648.

[3] The liquid-crystalline polyester resin composition according to [1] or [2], wherein,

the rockwell hardness of a test piece molded from the liquid crystal polyester resin composition is 108 or more and 115 or less as measured using an R scale according to ASTM D785.

[4] The liquid-crystalline polyester resin composition according to any one of [1] to [3],

the content of the filler is 24 parts by mass or more and 45 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester resin.

[5] The liquid-crystalline polyester resin composition according to any one of [1] to [4],

the ratio (W1/W2) of the mass (W1) of the fibrous filler to the mass (W2) of the plate-like filler is 0.5 to 2.0.

[6] The liquid-crystalline polyester resin composition according to any one of [1] to [5],

the plate-like filler has a volume average particle diameter of 5 to 50 [ mu ] m.

[7] The liquid-crystalline polyester resin composition according to any one of [1] to [6],

the liquid crystal polyester resin is a mixture of a plurality of liquid crystal polyester resins having different flow starting temperatures, and among the plurality of liquid crystal polyester resins, the flow starting temperature of a first liquid crystal polyester resin having the highest flow starting temperature is 300 ℃ to 400 ℃, and the flow starting temperature of a second liquid crystal polyester resin having the lowest flow starting temperature is 260 ℃ to 350 ℃.

[8] A molded article, wherein,

the liquid-crystalline polyester resin composition according to any one of [1] to [7 ].

Effects of the invention

According to an aspect of the present invention, there is provided a liquid crystal polyester resin composition capable of producing a molded article having excellent sheet fluidity, small warpage and high hardness. Also disclosed is a molded article which is molded from such a liquid crystal polyester resin composition and has low warpage and high hardness.

Drawings

FIG. 1 is a schematic view showing a die for measuring a flow length of a sheet used in examples.

FIG. 2 is a plan view showing a cavity of a weld strength measuring mold used in examples.

Fig. 3A is a schematic top view of a connector 200 made by an embodiment.

Fig. 3B is a schematic cross-sectional view of connector 200 made by an embodiment at section C-C of fig. 3A.

Fig. 3C is a schematic side view of a connector 200 made by an embodiment.

Fig. 4 is a diagram showing a breakage test of the connector 200 according to the embodiment.

Fig. 5 is a diagram showing a measurement position of the warpage amount of the connector 200 according to the embodiment.

Detailed Description

< liquid crystal polyester resin composition >

The liquid crystal polyester resin composition of the present embodiment includes: a liquid crystal polyester resin; and a filler composed of a fibrous filler and a plate-like filler.

[ liquid-crystalline polyester resin ]

One embodiment of the liquid crystal polyester resin used in the present embodiment will be described.

The liquid crystal polyester resin used in the present embodiment is a polyester that exhibits liquid crystal in a molten state, and is preferably a polyester that melts at a temperature of 450 ℃. The liquid crystal polyester resin may be a liquid crystal polyester amide, a liquid crystal polyester ether, a liquid crystal polyester carbonate, or a liquid crystal polyester imide. The liquid crystal polyester resin is preferably a wholly aromatic liquid crystal polyester resin obtained by polymerizing only an aromatic compound as a raw material monomer.

Typical examples of the liquid crystal polyester resin used in the present embodiment include: a substance obtained by polycondensing an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxylamine, and an aromatic diamine; a substance obtained by polymerizing a plurality of aromatic hydroxycarboxylic acids; a substance obtained by polymerizing an aromatic dicarboxylic acid and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxylamine and an aromatic diamine; and a polyester such as polyethylene terephthalate and an aromatic hydroxycarboxylic acid.

Among these, preferred is one obtained by polycondensation of an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxylamine, and an aromatic diamine.

Here, the aromatic hydroxycarboxylic acid, the aromatic dicarboxylic acid, the aromatic diol, the aromatic hydroxylamine and the aromatic diamine may be polymerizable ester-forming derivatives to replace a part or all of them independently of each other.

As examples of polymerizable derivatives of compounds having a carboxyl group like aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids, esters, acid halides, and acid anhydrides can be mentioned. Examples of the ester include those obtained by converting a carboxyl group into an alkoxycarbonyl group or an aryloxycarbonyl group. Examples of the acidic halide include those obtained by converting a carboxyl group into a haloformyl group. Examples of the acid anhydride include those obtained by converting a carboxyl group into an acyloxycarbonyl group.

Examples of polymerizable derivatives of compounds having a hydroxyl group such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxylamines include compounds (acylates) obtained by acylating a hydroxyl group to convert the hydroxyl group into an acyloxy group.

Examples of polymerizable derivatives of compounds having an amino group, such as aromatic hydroxylamine and aromatic diamine, include compounds (acylates) obtained by acylating an amino group and converting the amino group into an acylamino group.

In an example of the polymerizable derivative, as a raw material monomer of the liquid crystal polyester resin, an acylate obtained by acylating an aromatic hydroxycarboxylic acid and an aromatic diol is preferable.

The liquid crystal polyester resin used in the present embodiment preferably has a repeating unit represented by the following formula (1) (hereinafter, sometimes referred to as "repeating unit (1)"). Further, the liquid crystal polyester resin more preferably has a repeating unit (1), a repeating unit represented by the following formula (2) (hereinafter, referred to as "repeating unit (2)"), and a repeating unit represented by the following formula (3) (hereinafter, referred to as "repeating unit (3)").

(1)-O-Ar¹-CO-

(2)-CO-Ar²-CO-

(3)-X-Ar³-Y-

[ formula (1) to formula (3) wherein Ar is¹Represents phenylene, naphthylene or biphenylene.

Ar²And Ar³And independently represents phenylene, naphthylene, biphenylene or a group represented by formula (4). X and Y, independently of each otherAnd represents an oxygen atom or an imino group (-NH-).

From Ar¹、Ar²Or Ar³One or more hydrogen atoms in the group may be independently substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.]

(4)-Ar⁴-Z-Ar⁵-

[ formula (4) wherein Ar is⁴And Ar⁵And, independently of one another, represents phenylene or naphthylene. Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group or an alkylene group having 1 to 10 carbon atoms.

From Ar⁴Or Ar⁵One or more hydrogen atoms in the group may be independently substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms.]

Examples of the halogen atom which can substitute for a hydrogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Examples of the alkyl group having 1 to 10 carbon atoms which may be substituted for a hydrogen atom include methyl, ethyl, 1-propyl, isopropyl, 1-butyl, isobutyl, sec-butyl, tert-butyl, 1-hexyl, 2-ethylhexyl, 1-octyl and 1-decyl groups.

Examples of the aryl group having 6 to 20 carbon atoms which may be substituted with a hydrogen atom include monocyclic aromatic groups such as a phenyl group, an o-tolyl group, an m-tolyl group, and a p-tolyl group; a fused ring aromatic group such as a 1-naphthyl group or a 2-naphthyl group.

From Ar¹、Ar²、Ar³、Ar⁴Or Ar⁵In the groups represented by (A), in the case where one or more hydrogen atoms are substituted with the above-mentioned substituent(s), the number of the substituent(s) is each represented by Ar¹、Ar²、Ar³、Ar⁴Or Ar⁵In the groups represented, independently of one another, one or two are preferred. In addition, the number of the substituents is each independently Ar¹、Ar²、Ar³、Ar⁴Or Ar⁵Among the groups represented, one is more preferable.

Examples of the alkylene group having 1 to 10 carbon atoms include a methylene group, an ethylene group, an isopropylene group, a 1-butylene group, and a 2-ethylhexyl group.

The repeating unit (1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid.

In the present specification, "derived from" means that a raw material monomer changes its chemical structure for polymerization and does not change its structure.

Examples of the aromatic hydroxycarboxylic acid include 4-hydroxybenzoic acid, m-hydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 2-hydroxy-3-naphthoic acid, 1-hydroxy-5-naphthoic acid, and 4-hydroxy-4' -carboxydiphenyl ether; these aromatic hydroxycarboxylic acids have a part of hydrogen atoms in the aromatic ring thereof substituted with a substituent selected from the group consisting of the alkyl group, the aryl group and a halogen atom.

The aromatic hydroxycarboxylic acid may be used alone or in combination of two or more in the production of the liquid crystal polyester resin.

As the repeating unit (1), Ar is preferred¹Repeating units of 1, 4-phenylene (repeating units derived from 4-hydroxybenzoic acid) and Ar¹Is a repeating unit of 2, 6-naphthylene group (repeating unit derived from 6-hydroxy-2-naphthoic acid).

The repeating unit (2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, biphenyl-4, 4 ' -dicarboxylic acid, 2, 6-naphthalenedicarboxylic acid, diphenyl ether-4, 4 ' -dicarboxylic acid, and diphenyl sulfide-4, 4 ' -dicarboxylic acid; these aromatic dicarboxylic acids have a part of hydrogen atoms in the aromatic ring thereof substituted with a substituent selected from the group consisting of an alkyl group, an aryl group and a halogen atom.

The aromatic dicarboxylic acid may be used alone or in combination of two or more kinds in the production of the liquid crystal polyester resin.

As the repeating unit (2), Ar is preferred²Repeating units (e.g. sources) being 1, 4-phenyleneRepeating units derived from terephthalic acid), Ar²Repeating units of 1, 3-phenylene (e.g., repeating units derived from isophthalic acid), Ar²Are repeating units of 2, 6-naphthylene (e.g., repeating units derived from 2, 6-naphthalenedicarboxylic acid) and Ar²Are diphenyl ether-4, 4 '-diyl repeating units (e.g., repeating units derived from diphenyl ether-4, 4' -dicarboxylic acid).

The repeating unit (3) is a repeating unit derived from a predetermined aromatic diol, aromatic hydroxylamine or aromatic diamine.

Examples of the aromatic diol, aromatic hydroxylamine or aromatic diamine include 4,4 ' -dihydroxybiphenyl, hydroquinone, resorcinol, 4 ' -dihydroxybenzophenone, 4 ' -dihydroxydiphenyl ether, bis (4-hydroxyphenyl) methane, 1, 2-bis (4-hydroxyphenyl) ethane, 4 ' -dihydroxydiphenyl sulfone, 4 ' -dihydroxydiphenyl sulfide, 2, 6-dihydroxynaphthalene, 1, 5-dihydroxynaphthalene, 4-aminophenol, 1, 4-phenylenediamine, 4-amino-4 ' -hydroxybiphenyl, and 4,4 ' -diaminobiphenyl.

The aromatic diol, the aromatic hydroxylamine or the aromatic diamine may be used alone or in combination of two or more kinds in the production of the liquid crystal polyester resin.

As the repeating unit (3), Ar is preferred³Repeating units which are 1, 4-phenylene (e.g., repeating units derived from hydroquinone, 4-aminophenol or 1, 4-phenylenediamine) and Ar³Is a repeating unit of 4,4 '-biphenylene (e.g., a repeating unit derived from 4, 4' -dihydroxybiphenyl, 4-amino-4 '-hydroxybiphenyl, or 4, 4' -diaminobiphenyl).

When a molded article obtained from the liquid crystal polyester resin composition of the present embodiment is particularly required to have good heat resistance and thermal stability, the number of substituents contained in the repeating units (1) to (3) is preferably small. In addition, when a molded article obtained from the liquid crystal polyester resin composition of the present embodiment is particularly required to have good heat resistance and thermal stability, it is preferable that the molded article does not have a substituent (e.g., an alkyl group) having poor heat resistance.

The heat resistance of the molded article in the present embodiment means a property that a resin forming the molded article is hardly softened by overheating. In the present embodiment, the heat resistance of the molded article can be determined by measuring the deflection temperature under load of a test piece molded from the resin composition of the present embodiment. The deflection temperature under load in the present embodiment was measured under a load of 1.82MPa in accordance with ASTM D648. Specifically, the resin composition of the present embodiment was molded into a test piece of 127mm × 12.7mm × 6.4 mmt. The test piece was heated with the heat transfer medium under a load of 1.82MPa at a heating rate of 4 ℃ per minute, and the temperature at which the deflection was 0.25mm was measured. The average value is taken as the deflection temperature under load in the present embodiment. It can be said that the higher the deflection temperature under load of the test piece measured in this way, the higher the heat resistance of the molded article of the present embodiment.

The thermal stability of the molded article in the present embodiment means that decomposition and deterioration of the resin are less likely to occur when the molded article is held at a temperature (melting temperature) at which the resin is molded and processed.

Next, the combination of the structural units of the liquid crystal polyester resin particularly suitable for the present embodiment will be described in detail together with the examples of the structural units.

Specific examples of preferred liquid crystal polyester resins used in the present embodiment include copolymers composed of monomer-derived constituent units, which are specifically exemplified below.

(a) 4-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid copolymer

(b) 4-hydroxybenzoic acid/terephthalic acid/4, 4' -dihydroxybiphenyl copolymer

(c) 4-hydroxybenzoic acid/terephthalic acid/isophthalic acid/4, 4' -dihydroxybiphenyl copolymer

(d) 4-hydroxybenzoic acid/terephthalic acid/isophthalic acid/4, 4' -dihydroxybiphenyl/hydroquinone copolymer

(e) 4-hydroxybenzoic acid/terephthalic acid/hydroquinone copolymer

(f) 2-hydroxy-6-naphthoic acid/terephthalic acid/hydroquinone copolymer

(g) 4-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid/terephthalic acid/4, 4' -dihydroxybiphenyl copolymer

(h) 2-hydroxy-6-naphthoic acid/terephthalic acid/4, 4' -dihydroxybiphenyl copolymer

(i) 4-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid/terephthalic acid/hydroquinone copolymer

(j) 4-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid/terephthalic acid/hydroquinone/4, 4' -dihydroxybiphenyl copolymer

(k) 4-hydroxybenzoic acid/2, 6-naphthalenedicarboxylic acid/4, 4' -dihydroxybiphenyl copolymer

(l) 4-hydroxybenzoic acid/terephthalic acid/2, 6-naphthalenedicarboxylic acid/hydroquinone copolymer

(m) 4-hydroxybenzoic acid/2, 6-naphthalenedicarboxylic acid/hydroquinone copolymer

(n) 4-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid/2, 6-naphthalenedicarboxylic acid/hydroquinone copolymer

(o) 4-hydroxybenzoic acid/terephthalic acid/2, 6-naphthalenedicarboxylic acid/hydroquinone/4, 4' -dihydroxybiphenyl copolymer

(p) 4-hydroxybenzoic acid/terephthalic acid/4-aminophenol copolymer

(q) 2-hydroxy-6-naphthoic acid/terephthalic acid/4-aminophenol copolymer

(r) 4-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid/terephthalic acid/4-aminophenol copolymer

(s) 4-hydroxybenzoic acid/terephthalic acid/4, 4' -dihydroxybiphenyl/4-aminophenol copolymer

(t) 4-hydroxybenzoic acid/terephthalic acid/ethylene glycol copolymer

(u) 4-hydroxybenzoic acid/terephthalic acid/4, 4' -dihydroxybiphenyl/ethylene glycol copolymer

(v) 4-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid/terephthalic acid/ethylene glycol copolymer

(w) 4-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid/terephthalic acid/4, 4' -dihydroxybiphenyl/ethylene glycol copolymer

(x) 4-hydroxybenzoic acid/terephthalic acid/2, 6-naphthalenedicarboxylic acid/4, 4' -dihydroxybiphenyl copolymer

Among the examples, preferred are (b) and (c), and more preferred is (c).

The content of the repeating unit (1) in the liquid crystal polyester resin is preferably 30 mol% or more, more preferably 30 mol% or more and 80 mol% or less, further preferably 30 mol% or more and 70 mol% or less, and particularly preferably 35 mol% or more and 65 mol% or less, based on the total molar amount of all the repeating units constituting the liquid crystal polyester resin. The total molar amount of all repeating units constituting the liquid crystal polyester resin is a value obtained by dividing the mass of each repeating unit constituting the liquid crystal polyester resin by the chemical formula weight of each repeating unit to determine the mass equivalent (mole) of each repeating unit and summing these.

When the content of the repeating unit (1) of the liquid crystal polyester resin is 30 mol% or more relative to the total molar amount of the total repeating units constituting the liquid crystal polyester resin, the heat resistance and hardness of a molded article molded from the liquid crystal polyester resin composition of the present embodiment are easily improved. In addition, when the content of the repeating unit (1) is 80 mol% or less with respect to the total molar amount of the total repeating units constituting the liquid crystal polyester resin, the melt viscosity can be reduced. Therefore, the temperature required for molding the liquid crystal polyester resin is easily lowered.

The content of the repeating unit (2) in the liquid crystal polyester resin is preferably 35 mol% or less, more preferably 10 mol% or more and 35 mol% or less, further preferably 15 mol% or more and 35 mol% or less, and particularly preferably 17.5 mol% or more and 32.5 mol% or less, based on the total molar amount of all the repeating units constituting the liquid crystal polyester resin.

The content of the repeating unit (3) in the liquid crystal polyester resin is preferably 35 mol% or less, more preferably 10 mol% or more and 35 mol% or less, further preferably 15 mol% or more and 35 mol% or less, and particularly preferably 17.5 mol% or more and 32.5 mol% or less, based on the total molar amount of all the repeating units constituting the liquid crystal polyester resin.

In the liquid crystal polyester resin, the ratio of the content of the repeating unit (2) to the content of the repeating unit (3) is preferably 0.9/1 to 1/0.9, more preferably 0.95/1 to 1/0.95, and further preferably 0.98/1 to 1/0.98, as represented by [ the content of the repeating unit (2) ]/[ the content of the repeating unit (3) ] (mol/mol).

The liquid crystal polyester resin may have only one kind of the repeating units (1) to (3), or two or more kinds of the repeating units, independently of each other. In addition, the total content of the repeating units (1) to (3) in the liquid crystal polyester resin does not exceed 100 mol% based on the total repeating units constituting the liquid crystal polyester resin. The liquid crystal polyester resin may further have one or more kinds of repeating units other than the repeating units (1) to (3), and the content thereof is preferably 10 mol% or less, more preferably 5 mol% or less, based on the total molar amount of all the repeating units constituting the liquid crystal polyester resin.

[ Process for producing liquid-crystalline polyester resin ]

Next, an example of a method for producing a liquid crystal polyester resin used in the present embodiment will be described.

The liquid crystal polyester resin of the present embodiment is preferably produced by the following acylation step and polymerization step.

The acylation step is a step of acylating a phenolic hydroxyl group of a raw material monomer with a fatty acid anhydride (e.g., acetic anhydride) to obtain an acylate.

In the polymerization step, the acyl group of the acylate obtained in the acylation step and the carboxyl group of the acylate of the aromatic dicarboxylic acid and the aromatic hydroxycarboxylic acid may be polymerized to initiate ester interchange to obtain a liquid-crystalline polyester resin.

The acylation step and the polymerization step may be carried out in the presence of a heterocyclic organic basic compound represented by the following formula (5).

[ solution 1]

In the above formula (5), R₁～R₄Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxymethyl group, a cyano group, or a carbon atom of an alkyl groupCyanoalkyl having 1 to 4 subunits, cyanoalkoxy having 1 to 4 carbon atoms as the alkoxy group, carboxyl, amino, aminoalkyl having 1 to 4 carbon atoms, aminoalkoxy having 1 to 4 carbon atoms, phenyl, benzyl, phenylpropyl or formyl.

Among the heterocyclic organic basic compounds of the above formula (5), R in the above formula (5) is preferable₁Is alkyl of 1-4 carbon atoms, R₂～R₄Imidazole derivatives each being a hydrogen atom. This can further improve the reactivity of the acylation reaction in the acylation step and the transesterification reaction in the polymerization step. In addition, the color tone of the molded article obtained using the liquid crystal polyester resin composition of the present embodiment can be further improved.

Among the heterocyclic organic basic compounds, from the viewpoint of easy availability, any one or both of 1-methylimidazole and 1-ethylimidazole are particularly preferable.

The amount of the heterocyclic organic basic compound used is preferably 0.005 to 1 part by mass, based on 100 parts by mass of the total amount of the raw material monomers (i.e., the aromatic dicarboxylic acid, the aromatic diol, and the aromatic hydroxycarboxylic acid) of the liquid crystal polyester resin.

From the viewpoint of color tone and productivity of the molded article, the amount is more preferably 0.05 to 0.5 parts by mass per 100 parts by mass of the raw material monomer.

The heterocyclic organic basic compound may be present at one stage during the acylation reaction and the ester exchange reaction, and the addition period may be immediately before the start of the acylation reaction, may be in the middle of the acylation reaction, or may be between the acylation reaction and the ester exchange reaction.

The liquid-crystalline polyester resin thus obtained has very high melt flowability and excellent thermal stability.

The amount of the fatty acid anhydride (e.g., acetic anhydride) to be used is determined in consideration of the amounts of the aromatic diol and the aromatic hydroxycarboxylic acid to be used as the raw material monomers. Specifically, the equivalent is preferably 1.0 to 1.2 times, more preferably 1.0 to 1.15 times, still more preferably 1.03 to 1.12 times, and particularly preferably 1.05 to 1.1 times the total of the phenolic hydroxyl groups contained in the raw material monomers.

When the amount of the fatty acid anhydride used is 1.0 equivalent or more to the total amount of the phenolic hydroxyl groups contained in the raw material monomers, the acylation reaction is easily performed, and it is difficult for unreacted raw material monomers to remain in the subsequent polymerization step, and as a result, the polymerization is efficiently performed. When the acylation reaction is sufficiently performed in this manner, the non-acylated raw material monomer is sublimated, and the fractionator used in the polymerization is less likely to be clogged. On the other hand, when the amount of the fatty acid anhydride used is 1.2 times equivalent or less, the obtained liquid crystal polyester resin is less likely to be colored.

The acylation reaction in the acylation step is preferably carried out at a temperature of 130 to 180 ℃ for 30 minutes to 20 hours, more preferably at 140 to 160 ℃ for 1 to 5 hours.

The aromatic dicarboxylic acid used in the polymerization step may be present in the reaction system during the acylation step. That is, in the acylation step, the aromatic diol, the aromatic hydroxycarboxylic acid, and the aromatic dicarboxylic acid may be present in the same reaction system.

This is because both the carboxyl group and the optionally substituted substituent in the aromatic dicarboxylic acid are not affected at all by the fatty acid anhydride.

Therefore, the method may be a method in which the acylation step and the polymerization step are sequentially performed after the aromatic diol, the aromatic hydroxycarboxylic acid, and the aromatic dicarboxylic acid are fed into the reactor, or a method in which the acylation step is performed after the aromatic diol and the aromatic dicarboxylic acid are fed into the reactor, and the polymerization step is further performed after the aromatic dicarboxylic acid is fed into the reactor. The former method is preferable from the viewpoint of simplifying the production process.

The transesterification reaction in the polymerization step is preferably carried out while raising the temperature from 130 ℃ to 400 ℃ at a rate of temperature rise of 0.1 to 50 ℃/min, and more preferably from 150 ℃ to 350 ℃ at a rate of temperature rise of 0.3 to 5 ℃/min.

In addition, in the transesterification reaction in the polymerization step, it is preferable to evaporate by-produced fatty acids (e.g., acetic acid) and unreacted fatty acid anhydrides (e.g., acetic anhydride) and distill them off the system in order to shift the equilibrium. At this time, by returning a part of the distilled fatty acid to the reactor by refluxing, the raw material monomer or the like evaporated or sublimed together with the fatty acid can be condensed or inversely sublimed and returned to the reactor.

In the acylation reaction in the acylation step and the ester exchange reaction in the polymerization step, a batch apparatus or a continuous apparatus may be used as the reactor. The liquid crystal polyester resin that can be used in the present embodiment can be obtained by using any reaction apparatus.

After the polymerization step, a step of increasing the molecular weight of the liquid crystal polyester resin obtained in the polymerization step may be performed. For example, a liquid crystal polyester resin obtained in the polymerization step is cooled and then pulverized to prepare a liquid crystal polyester resin in a powder form, and if this powder is heated, the liquid crystal polyester resin can be increased in molecular weight.

Further, it is also possible to increase the molecular weight of the liquid crystal polyester resin by granulating the powdery liquid crystal polyester resin obtained by cooling and pulverizing to prepare a granular liquid crystal polyester resin, and thereafter heating the granular liquid crystal polyester resin. The high molecular weight polymerization using these methods is referred to as solid-phase polymerization in the art.

Solid-phase polymerization is particularly effective as a method for increasing the molecular weight of a liquid crystal polyester resin.

By making the liquid crystal polyester resin have a high molecular weight, a liquid crystal polyester resin having an appropriate flow starting temperature described later can be easily obtained.

As the reaction conditions for the solid-phase polymerization, a method of heat-treating a liquid-crystalline polyester resin in a solid state in an inert gas atmosphere or under reduced pressure for 1 to 20 hours is generally employed. The polymerization conditions for carrying out the solid-phase polymerization can be appropriately optimized after the flow initiation temperature of the liquid-crystalline polyester resin obtained by the melt polymerization is determined.

Examples of the apparatus used for the heat treatment include a known dryer, a known reactor, a known inert oven, and a known electric furnace.

The flow initiation temperature of the liquid crystal polyester resin is preferably 270 ℃ or higher, more preferably 270 to 400 ℃, and still more preferably 280 to 380 ℃. When the liquid crystal polyester resin having the flow start temperature in such a range is used, it can be expected to improve the heat resistance and hardness of a molded article obtained by using the liquid crystal polyester resin composition of the present embodiment. In addition, in the melt molding when obtaining a molded article from the liquid crystal polyester resin composition, the thermal stability of the liquid crystal polyester resin can be improved and thermal degradation can be avoided.

The flow start temperature is also referred to as a viscous flow temperature or a flow temperature, and the liquid crystal polyester resin is melted by heating at a rate of 4 ℃/min under a load of 9.8MPa using a capillary rheometer, and the temperature at which the viscosity of 4800Pa · s (48000 poise) is exhibited when the liquid crystal polyester resin is extruded from a nozzle having an inner diameter of 1mm and a length of 10mm becomes a standard for the molecular weight of the liquid crystal polyester resin (for example, see xiao hou sho, published entitled "liquid crystal polymer-synthesis/molding/application- (liquid crystal ポリマー -synthesis/molding/application"), (pages 95 to 105, CMC (シーエムシー), issued 6/5/1987).

The above-mentioned liquid-crystalline polyester resin having a flow start temperature in an appropriate range can be easily obtained by appropriately optimizing the structural unit constituting the liquid-crystalline polyester resin. That is, when the linearity of the molecular chain of the liquid crystal polyester resin is improved, the flow starting temperature tends to be increased.

For example, among the structural units derived from the aromatic dicarboxylic acid, terephthalic acid improves the linearity of the molecular chain of the liquid crystal polyester resin, and isophthalic acid improves the bendability (reduces the linearity) of the molecular chain of the liquid crystal polyester resin. Therefore, by controlling the copolymerization ratio of terephthalic acid and isophthalic acid, a liquid crystal polyester resin having a desired flow initiation temperature can be obtained.

In the present embodiment, a liquid crystal polyester resin mixture (hereinafter, resin mixture) obtained by mixing a plurality of liquid crystal polyester resins may be used. In this case, the at least one liquid crystal polyester resin is preferably obtained by polymerizing a raw material monomer containing an aromatic hydroxycarboxylic acid in the presence of an imidazole derivative. The liquid-crystalline polyester resin thus obtained has extremely high melt flowability and excellent thermal stability (retention stability).

In the liquid crystal polyester resin used in the present embodiment, the copolymerization ratio of the structural units of terephthalic acid and isophthalic acid is preferably optimized. Thereby, the linearity of the molecular chain of the liquid crystal polyester resin can be controlled as described above. As a result, a plurality of liquid crystal polyester resins having different flow starting temperatures can be produced.

Here, as the resin mixture, a mixture of two liquid crystal polyester resins having mutually different flow starting temperatures is assumed. In this resin mixture, the liquid crystal polyester resin having a high flow start temperature is set as a first liquid crystal polyester resin, and the liquid crystal polyester resin having a low flow start temperature is set as a second liquid crystal polyester resin.

When the molar ratio of the first liquid crystal polyester resin (isophthalic acid/terephthalic acid) is α and the molar ratio of the second liquid crystal polyester resin (isophthalic acid/terephthalic acid) is β, the ratio of the molar ratio of the second liquid crystal polyester resin to the molar ratio of the first liquid crystal polyester resin (α/β) is preferably in the range of 0.1 to 0.6, and more preferably in the range of 0.3 to 0.6.

In the present embodiment, a resin mixture containing the first liquid crystal polyester resin and the second liquid crystal polyester resin is preferably used. As a result, the liquid crystal polyester resin composition of the present embodiment has better melt flowability, and the warpage of a molded article obtained from the liquid crystal polyester resin composition can be sufficiently suppressed.

The lower limit of the flow start temperature of the first liquid-crystalline polyester resin is preferably 300 ℃, more preferably 310 ℃, and still more preferably 315 ℃. The upper limit of the flow start temperature of the first liquid-crystalline polyester resin is preferably 400 ℃, more preferably 360 ℃, and still more preferably 345 ℃. The upper limit value and the lower limit value may be arbitrarily combined. For example, the flow starting temperature of the first liquid crystal polyester resin is preferably 300 ℃ or higher and 400 ℃ or lower, more preferably 310 ℃ or higher and 360 ℃ or lower, and still more preferably 315 ℃ or higher and 345 ℃ or lower.

When the flow starting temperature of the first liquid-crystalline polyester resin is within the above range, there is a tendency that the balance between the melt flowability of the mixed resin and the heat resistance of the obtained molded article becomes good.

On the other hand, the lower limit of the flow start temperature of the second liquid-crystalline polyester resin is preferably 260 ℃, more preferably 270 ℃, and still more preferably 285 ℃. The upper limit of the flow initiation temperature of the second liquid-crystalline polyester resin is preferably 350 ℃, more preferably 320 ℃, and still more preferably 315 ℃. The upper limit value and the lower limit value may be arbitrarily combined. For example, the flow starting temperature of the second liquid-crystalline polyester resin is preferably 260 ℃ to 350 ℃, more preferably 270 ℃ to 320 ℃, and still more preferably 285 ℃ to 315 ℃.

When the flow starting temperature of the second liquid-crystalline polyester resin is within the above range, the sheet fluidity tends to be good, and the load deflection temperature of a molded article obtained from the resin mixture tends to be sufficiently high.

In addition, in the resin mixture, the content of the second liquid crystal polyester resin is preferably 10 to 150 parts by mass, more preferably 30 to 120 parts by mass, and even more preferably 50 to 100 parts by mass, relative to 100 parts by mass of the first liquid crystal polyester resin.

The content of the second liquid crystal polyester resin relative to the first liquid crystal polyester resin is appropriately set by a balance between a deflection temperature under load of the resin mixture and a fluidity of a sheet.

The resin mixture may contain a liquid crystal polyester resin other than the first liquid crystal polyester resin and the second liquid crystal polyester resin. In this case, the liquid crystal polyester resin having the highest flow starting temperature in the resin mixture may be referred to as the first liquid crystal polyester resin, and the liquid crystal polyester resin having the lowest flow starting temperature may be referred to as the second liquid crystal polyester resin. A resin mixture substantially composed of only the first liquid-crystalline polyester resin and the second liquid-crystalline polyester resin is preferable.

[ Filler ]

The liquid crystal polyester resin composition of the present embodiment contains 15 parts by mass or more and 55 parts by mass or less of a filler composed of a fibrous filler and a plate-like filler, based on 100 parts by mass of the liquid crystal polyester resin.

When the content of the filler is 15 parts by mass or more, the strength and hardness of the obtained molded article become sufficiently high. On the other hand, when the content of the filler is less than 15 parts by mass, warpage is likely to occur in a molded article obtained while the heat resistance and mechanical properties of the liquid crystal polyester resin composition are insufficient.

When the content of the filler is 55 parts by mass or less, the sheet fluidity at the time of molding becomes sufficiently high. On the other hand, when the content of the filler exceeds 55 parts by weight, the melt flowability of the liquid crystal polyester resin composition is deteriorated and bubbles are likely to be generated.

The lower limit of the filler content used in the present embodiment is preferably 24 parts by mass, and more preferably 32 parts by mass, based on 100 parts by mass of the liquid crystal polyester resin. The upper limit of the filler content is preferably 45 parts by mass, and more preferably 42 parts by mass. The above upper limit value and lower limit value can be arbitrarily combined. For example, the content of the filler used in the present embodiment is preferably 24 parts by mass or more and 45 parts by mass or less, and more preferably 32 parts by mass or more and 42 parts by mass or less, with respect to 100 parts by mass of the liquid crystal polyester resin.

When the total amount of the plate-like filler and the fibrous filler is within the above range, warpage of the obtained molded article is less likely to occur while the heat resistance and the weld strength of the liquid crystal polyester resin composition become more excellent.

In the liquid crystal polyester resin composition of the present embodiment, the content of the fibrous filler is preferably 5 to 30 parts by mass, and more preferably 10 to 30 parts by mass, based on 100 parts by mass of the liquid crystal polyester resin. When the content of the fibrous filler is within the above range, the liquid crystal polyester resin composition is more excellent in heat resistance and mechanical properties.

In the liquid crystal polyester resin composition of the present embodiment, the content of the plate-like filler is preferably 5 to 30 parts by mass, and more preferably 10 to 30 parts by mass, based on 100 parts by mass of the liquid crystal polyester resin.

In the liquid crystal polyester resin composition of the present embodiment, the ratio (W1/W2) of the fibrous filler content mass (W1) to the plate-like filler content mass (W2) is preferably in the range of 0.5 to 2.0, more preferably in the range of 0.6 to 1.8, and particularly preferably in the range of 0.8 to 1.2.

(fibrous Filler)

The number average fiber length of the fibrous filler contained in the liquid crystal polyester resin composition of the present embodiment is 450 to 700 μm. When the number average fiber length of the fibrous filler is 450 μm or more, the mechanical strength and hardness of the obtained molded article become sufficiently high.

In the present embodiment, the hardness of the molded article is also referred to as "surface hardness" or "rockwell hardness". The hardness of the molded article was measured by molding a test piece having a thickness of 6.4mm and measuring the hardness with a test load of 588.4N using an R scale (steel ball having a diameter of 12.7 mm) according to ASTM D785 using a Rockwell hardness tester (FR-1E, manufactured by Toyo Seiki Seisaku-sho Co., Ltd.). This was performed three times, and the average value thereof was used as the hardness of the molded article of the present embodiment.

Here, it is important that the test piece has a thickness of 6mm or more and no pits (grooves) on the surface. If the thickness is thinner than 6mm, the bottom surface may be affected when the indenter is pressed in. Further, when there is a dent, a gap is generated in the holder surface of the molded product, and accurate measurement may not be performed when the indenter is pressed in.

The following factors may be considered as the factors for increasing the hardness of the molded article obtained. In general, a molded article made of a liquid crystal polyester resin composition as a molding material has a "skin layer" present on the surface of the molded article and a "core layer" present inside the molded article. In the case of using a liquid crystal polyester resin composition containing a fibrous filler, the fibrous filler is present in a large amount in the core layer of the molded article.

In contrast, in the liquid crystal polyester resin composition of the present embodiment, the number average fiber length of the fibrous filler is sufficiently long to be 450 μm or more. Therefore, when the liquid crystal polyester resin composition of the present embodiment is used, it is estimated that the fibrous filler is present from the core layer to the skin layer of the molded article.

Therefore, it is estimated that the molded article obtained using the liquid crystal polyester resin composition of the present embodiment has a larger amount of fibrous filler in the vicinity of the surface than the molded article obtained using the conventional liquid crystal polyester resin composition. In general, the fibrous filler is formed of a material having a higher mohs hardness than the liquid crystal polyester resin. Therefore, it is considered that the hardness of the molded article is increased as a result of the liquid crystal polyester resin composition of the present embodiment.

Here, the mohs hardness is an empirical scale for obtaining the hardness of a mineral by comparing it with ten kinds of reference minerals. The standard mineral is talc, gypsum, calcite, fluorite, apatite, orthoclase, quartz, topaz, corundum, and diamond in the order from a soft mineral (mohs hardness 1) to a hard mineral (mohs hardness 10), and the hardness is measured by scratching the standard mineral with a sample substance whose hardness is to be measured and determining the presence or absence of scratching. For example, when there is a scratch on fluorite and no scratch on apatite, the mohs hardness is 4.5 (between 4 and 5).

Further, when the number average fiber length of the fibrous filler is sufficiently long and 450 μm or more, the reinforcing effect on the obtained molded article is excellent. Therefore, the warpage of the molded article is considered to be reduced. The number average fiber length of the fibrous filler is sufficiently long at 450 μm or more, and the obtained molded article is excellent in dimensional stability.

The lower limit of the number average fiber length of the fibrous filler is preferably 470 μm, more preferably 500. mu.m, and still more preferably 520. mu.m.

On the other hand, when the number average fiber length of the fibrous filler of the present embodiment is 700 μm or less, the liquid crystal polyester resin composition can be stably obtained. In addition, when the number average fiber length of the fibrous filler is 700 μm or less, the flow inhibition of the liquid crystal polyester resin composition by the fibrous filler is less likely to occur. As a result, the liquid crystal polyester resin composition of the present embodiment can easily maintain the fluidity uniformly. Therefore, in the present embodiment, the liquid crystal polyester resin composition can be easily filled in the sheet portion or the narrow-pitch lattice portion of the molded article.

The upper limit of the number average fiber length of the fibrous filler is preferably 650 μm, more preferably 600. mu.m.

The lower limit and the upper limit of the number-average fiber length of the fibrous filler can be arbitrarily combined. For example, the number average fiber length of the fibrous filler is preferably 470 μm or more and 650 μm or less, more preferably 500 μm or more and 600 μm or less, and still more preferably 520 μm or more and 600 μm or less.

The number average fiber diameter of the fibrous filler of the present embodiment is preferably 5 μm or more and 20 μm or less. When the number average fiber diameter of the fibrous filler is 5 μm or more, the fibrous filler is not damaged more than necessary in the production of the liquid crystal polyester resin composition. As a result, the number average fiber length of the fibrous filler contained in the liquid crystal polyester resin composition can be controlled within the above range. In addition, when the number average fiber diameter of the fibrous filler is 20 μm or less, a decrease in hardness of the molded article due to a decrease in the fiber length-to-width ratio (ratio of fiber length/fiber diameter) can be avoided.

The number average fiber diameter of the fibrous filler of the present embodiment is more preferably 6 μm or more. The fiber diameter is more preferably 17 μm or less, and still more preferably 15 μm or less.

The number-average fiber length of the fibrous filler contained in the liquid crystal polyester resin composition can be adjusted by changing the melt-kneading conditions at the time of producing the liquid crystal polyester resin composition and the configuration of the extruder used for melt-kneading.

The number average fiber length of the fibrous filler contained in the liquid crystal polyester resin composition of the present embodiment was measured by the following method.

First, 5g of pellets of the liquid crystal polyester resin composition of the present embodiment was heated in a muffle furnace (for example, "FP 410" manufactured by ohyoku corporation) at 600 ℃ for 4 hours in an air atmosphere to remove the resin. The ashed residue containing the obtained fibrous filler was dispersed in an ethylene glycol solution, and ultrasonic waves were applied for 3 minutes.

Subsequently, a few drops of the dispersion were dropped onto the slide glass, and the fibrous fillers were disentangled on the slide glass so as not to overlap. The loosened fibrous filler is covered with a glass cover, and a focal length is adjusted by a video microscope (for example, "VHX-1000" manufactured by keyence corporation (キーエンス)) at a magnification of 100 times so that the focal point is on the contour of the fibrous filler. The length of 500 fibrous fillers was measured, and the number average fiber length was calculated.

The number average fiber diameter of the fibrous filler contained in the liquid crystal polyester resin composition of the present embodiment is measured as follows.

First, 5g of pellets of the liquid crystal polyester resin composition of the present embodiment was heated in a muffle furnace (for example, "FP 410" manufactured by ohyoku corporation) at 600 ℃ for 4 hours in an air atmosphere to remove the resin. The ashed residue containing the obtained fibrous filler was dispersed in an ethylene glycol solution, and ultrasonic waves were applied for 3 minutes.

Subsequently, a few drops of the dispersion were dropped onto the slide glass, and the fibrous fillers were disentangled on the slide glass so as not to overlap. The loosened fibrous filler is covered with a glass cover, and a focal length is adjusted at a magnification of 500 times by a video microscope (for example, "VHX-1000" manufactured by keyence corporation (キーエンス) to bring the focal point to the contour of the fibrous filler). The fiber diameters of 50 fibrous fillers were measured, and the number average fiber diameter was calculated.

The fibrous filler used in the present embodiment may be an inorganic filler or an organic filler. Further, the mohs hardness is preferably 4 or more.

Examples of the fibrous inorganic filler include glass fibers; carbon fibers such as PAN-based carbon fibers and pitch-based carbon fibers; ceramic fibers such as silica fibers, alumina fibers, silica alumina fibers, and the like; and metal fibers such as stainless steel fibers. Further, there may be mentioned whiskers such as potassium titanate whisker, barium titanate whisker, wollastonite whisker, aluminum borate whisker, silicon nitride whisker and silicon carbide whisker.

Examples of the fibrous organic filler include polyester fibers, aramid fibers, and cellulose fibers.

In the examples, glass fibers are preferable because they have excellent strength and are easily available.

(glass fiber)

In the present embodiment, the strength, heat resistance and surface hardness of the molded article can be improved by containing the glass fiber in the liquid crystal polyester resin composition.

Examples of the glass fiber include glass fibers produced by various methods, such as long-fiber type chopped glass fibers and short-fiber type milled glass fibers. Two or more of these can be used in combination.

Examples of the kind of the glass fiber include E-glass, A-glass, C-glass, D-glass, AR-glass, R-glass, S-glass, and mixtures thereof. Among them, E-glass is preferable because it is excellent in strength and easily available.

As the glass fiber, weakly basic glass fiber is excellent in mechanical strength (tensile strength and Izod impact strength), and can be preferably used. In particular, glass fibers having a silica content of 50 to 80 mass% based on the total mass of the glass fibers are preferably used, and glass fibers having a silica content of 65 to 77 mass% based on the total mass of the glass fibers are more preferably used.

The glass fiber may be one treated with a coupling agent such as a silane coupling agent or a titanium coupling agent as necessary.

The glass fiber may be coated with a thermoplastic resin such as a urethane resin, an acrylic resin, an ethylene/vinyl acetate copolymer, or a thermosetting resin such as an epoxy resin, or may be treated with a astringent.

The number average fiber length of the glass fibers as the raw materials to be supplied for melt kneading is preferably 500 to 6000 μm. When the number average fiber length of the glass fibers is 500 μm or more, the reinforcing effect on the obtained molded article is sufficiently high. In addition, when the number average fiber length of the glass fibers is 6000 μm or less, the number average fiber length of the glass fibers contained in the liquid crystal polyester resin composition after melt kneading can be easily adjusted to 700 μm or less.

The lower limit of the number average fiber length of the glass fibers as the raw materials to be supplied for melt kneading is more preferably 1000 μm, and still more preferably 2000 μm. The upper limit of the number average fiber length of the glass fibers is preferably 5000 μm, more preferably 4500 μm. The lower limit and the upper limit of the number average fiber length of the glass fibers can be arbitrarily combined. For example, the number average fiber length of the glass fibers is more preferably 1000 μm or more and 5000 μm or less, and still more preferably 2000 μm or more and 4500 μm or less.

The fiber diameter (filament diameter) of the glass fibers, which are the raw materials to be supplied to the melt kneading, is preferably 5 μm or more and 20 μm or less. When the fiber diameter of the glass fiber is 5 μm or more, the reinforcing effect on the obtained molded article is sufficiently high. When the fiber diameter of the glass fiber is 20 μm or less, the melt flowability of the liquid crystal polyester resin composition is sufficiently high.

The lower limit of the fiber diameter of the glass fiber, which is a raw material to be supplied for melt kneading, is more preferably 6 μm. The upper limit of the fiber diameter of the glass fiber is more preferably 17 μm, and still more preferably 15 μm. The lower limit and the upper limit of the average fiber diameter of the glass fiber can be arbitrarily combined. For example, the average fiber diameter of the glass fiber is more preferably 6 μm or more and 17 μm or less, and still more preferably 6 μm or more and 15 μm or less.

The diameter of the glass fiber was not substantially changed even after melt-kneading.

In the present specification, the "number average fiber length of glass fibers as a raw material" means a value measured by the method described in JIS R3420 "length of 7.8 chopped strands" unless otherwise specified. Specifically, 20 glass fibers were taken out of 10g or more of the glass fiber samples, measured with a length diameter having a minimum scale of 0.5mm or less, and an average value thereof was calculated, and a value rounded to one point below the decimal point was taken as the number average fiber length of the glass fibers as the raw material.

The "fiber diameter of the glass fiber as a raw material" means a value measured by the "a method" in the method described in JIS R3420 "7.6 single fiber diameter" unless otherwise specified. Specifically, the profile of glass fiber placed in a liquid having a refractive index different from that of glass was observed, and the diameter was measured.

(plate-like Filler)

Examples of the plate-like filler include talc, mica, graphite, wollastonite, glass flake, barium sulfate and calcium carbonate. The mica can be muscovite, phlogopite, fluorophlogopite or tetrasilicic mica.

The platy filler is preferably talc or mica, and more preferably talc, among others. The liquid crystal polyester resin composition of the present embodiment contains talc or mica, and thus can reduce warpage of a molded article and improve heat resistance and hardness of the molded article.

Talc

The talc used in the present embodiment is a mineral powder composed of magnesium hydroxide and a silicate mineral. The talc used in the present embodiment has an octahedral structure in which three magnesium (Mg) oxide/hydroxide particles are sandwiched between four tetrahedral structures forming a tetraatomic silicon (Si) oxide.

Examples of the method for producing talc used in the present embodiment include known production methods, and examples thereof include a grinding-type pulverization method such as a roll mill and a raymond mill, an impact-type pulverization method such as an atomizer, a hammer mill and a micron mill, and a dry-type pulverization method such as an impact-type pulverization method such as a jet mill and a ball mill.

Further, a wet pulverization method may be used in which the pulverized talc powder is dispersed in water to form a slurry of flowable viscosity and pulverized by using a ball mill, a bead mill, a wet jet mill, ディスコプレックス, or the like. Among the above production methods, the dry pulverization method is preferable in terms of low cost and easy availability.

The surface of talc may be treated with a coupling agent or the like for the purpose of improving the wettability of talc and a resin (liquid crystal polyester resin). Further, talc processed by heat treatment may be used for the purpose of removing impurities and hardening the talc. In addition, compressed talc may be used for the purpose of easy use.

(screenings)

The 45 μm sieve residue of talc is preferably 1.0 mass% or less based on the total amount of talc. When the content is 1.0% by mass or less, clogging of the sheet portion during molding can be suppressed, moldability can be improved, and sheet strength can be improved. The 45 μm mesh residue contained in talc is preferably 0.8 mass% or less, more preferably 0.6 mass% or less, relative to the total amount of talc.

In the present specification, 45 μm sieve residue of talc is measured according to JIS K5101-14-1 "pigment test method-part 14: screen reject-first section: wet method (manual method) "measured value. Specifically, for example, the measurement is performed as follows. A sample having a sufficient amount of screen residue was weighed in a beaker having an appropriate capacity in an amount of 0.1g and dispersed in an appropriate amount of water (about 300 to 600 ml). The dispersion was poured into a sieve with a 45 μm mesh. The beaker was washed completely using a wash flask containing the solution for dispersing the sample, and the entire washing solution was sieved. The sieved washing liquid was washed with the same solution until clear and without dispersed material. The residue was washed into a previously heated and weighed sintered glass crucible, dried in a desiccator at 105. + -. 2 ℃ for 1 hour, and cooled in the desiccator, and weighed with an accuracy of 1 mg. The residual mass is calculated.

(ignition weight loss)

The weight loss on ignition (ig. loss) of talc is preferably 7 mass% or less, more preferably 6 mass% or less, and particularly preferably 5 mass% or less. The lower the loss, the more the decomposition of the liquid-crystalline polyester can be suppressed and the more the generation of bubbles becomes difficult. In the present invention, ig.loss is a value measured according to JIS M8853. Specifically, the platinum crucible and the lid were heated together at 1025. + -. 25 ℃ for 30 minutes, cooled to room temperature in a desiccator, and then the mass was measured. Next, 1.00g of the sample was taken in a crucible with a lid, and the mass was measured. Next, the lid was half-opened, initially heated at low temperature, gradually warmed to 1025 ± 25 ℃, scorched for 60 minutes at this temperature, fully opened and left to cool to normal temperature in a desiccator, and then the quality was measured. The ratio of the difference between the mass of the sample before ignition and the mass of the sample after ignition to the total mass of the sample before ignition was calculated as the ignition loss.

Mica

Mica is a ground silicate mineral containing aluminum, potassium, magnesium, sodium, iron, and the like. Mica is a mineral having an octahedral sandwich structure formed by two or three metal oxides and hydroxides between four tetrahedral structures formed by triatomic silicon (Si) and one atomic aluminum (Al) oxide.

The mica used in the present embodiment may be any of muscovite, phlogopite, fluorophlogopite, tetrasilicic mica, and artificially produced synthetic mica. These may be contained in two or more kinds.

The mica used in the present embodiment is preferably substantially composed of only muscovite.

Examples of the method for producing mica used in the present embodiment include water jet milling, wet milling, dry ball mill milling, pressure roller mill milling, jet mill milling, and dry milling by an impact mill such as an atomizer. Mica produced by a wet grinding method is preferably used because mica can be finely and thinly ground.

In the case of wet pulverization, mica before pulverization is dispersed in water. In this case, in order to improve the dispersion efficiency of mica before pulverization, polyaluminium chloride, aluminium sulfate, ferrous sulfate, ferric sulfate, copperaschloride (salt formed at コッパラス), ferric polysulfate, ferric chloride, iron-silica inorganic polymer coagulant, ferric chloride-silica inorganic polymer coagulant, and slaked lime (Ca (OH))₂) Caustic soda (NaOH) and soda ash (Na)₂CO₃) And additives such as coagulation sedimentation agents and sedimentation aids. However, these additives sometimes cause decomposition of the liquid-crystalline polyester. Therefore, the mica used in the present embodiment is preferably not subjected to coagulation and sedimentation during wet grindingMica for reducing adjuvant.

(volume average particle diameter)

The lower limit of the volume average particle diameter of the plate-like filler contained in the liquid crystal polyester resin composition of the present embodiment is preferably 5 μm. Thereby, warpage of the obtained molded body is reduced.

The lower limit of the volume average particle diameter of the plate-like filler contained in the liquid crystal polyester resin composition of the present embodiment is more preferably 5.5 μm, and still more preferably 6 μm.

The upper limit of the volume average particle diameter of the plate-like filler is preferably 50 μm. When the volume average particle diameter of the plate-like filler is 50 μm or less, the mixing property of the plate-like filler with the liquid crystal polyester resin becomes good, and the flow of the liquid crystal polyester resin composition is less likely to be inhibited. As a result, the fluidity of the liquid crystal polyester resin composition is easily and uniformly maintained. Therefore, the liquid crystal polyester resin composition can be easily filled in the sheet portion or the narrow-pitch lattice portion of the molded article.

The upper limit of the volume average particle diameter of the plate-like filler contained in the liquid crystal polyester resin composition of the present embodiment is more preferably 24 μm, still more preferably 20 μm, and particularly preferably 15 μm.

The lower limit and the upper limit of the volume average particle diameter of the plate-like filler can be arbitrarily combined. For example, the volume average particle diameter of the plate-like filler is preferably 5 μm or more and 50 μm or less, more preferably 5.5 μm or more and 24 μm or less, and still more preferably 6 μm or more and 20 μm or less.

In the present embodiment, the volume average particle diameter of the plate-like filler can be measured by a laser diffraction method. As the measuring apparatus, a scattering particle size distribution measuring apparatus (for example, "LA-950V 2" manufactured by HORIBA) can be used to calculate the volume average particle size under the following measurement conditions in a state in which the plate-like filler is dispersed in water.

< Condition >

Refractive index of particle: 1.57-0.1i (talc), 1.59-0.1i (mica)

Dispersion medium: water (W)

Refractive index of dispersion medium: 1.33 (in the case of water)

(thickness)

The lower limit of the thickness of the plate-like filler contained in the liquid crystal polyester resin composition of the present embodiment is preferably 0.10. mu.m, more preferably 0.20. mu.m, and still more preferably 0.30. mu.m. Thereby, the warpage of the obtained molded body can be reduced.

The upper limit of the thickness of the plate-like filler contained in the liquid crystal polyester resin composition of the present embodiment is preferably 1.0. mu.m, more preferably 0.95. mu.m, and still more preferably 0.90. mu.m. This enables the plate-like filler to be uniformly dispersed in the liquid crystal polyester resin composition. As a result, the fluidity of the liquid crystal polyester resin composition is easily and uniformly maintained. Therefore, the liquid crystal polyester resin composition can be easily filled in the sheet portion or the narrow-pitch lattice portion of the molded article.

The lower limit and the upper limit of the thickness of the plate-like filler can be arbitrarily combined. For example, the thickness of the plate-like filler is preferably 0.10 μm or more and 1.0 μm or less, more preferably 0.20 μm or more and 0.95 μm or less, and still more preferably 0.30 μm or more and 0.90 μm or less.

The thickness of the plate-like filler in the present embodiment is measured at a magnification of 1000 times using an electron microscope. The thickness of the plate-like packing of the present embodiment is an average value of values obtained by measuring randomly selected 1 or more plate-like packings thinly peeled.

[ other ingredients ]

The liquid crystal polyester resin composition of the present embodiment may contain one or more of fillers other than fibrous fillers and plate-like fillers, additives, and other components such as resins other than liquid crystal polyester resins within the range in which the effects of the present invention are exhibited.

The liquid crystal polyester resin composition of the present embodiment may contain a particulate filler as a filler other than the fibrous filler and the plate-like filler. The particulate filler may be an inorganic filler or an organic filler. The content of the filler other than the fibrous filler and the plate-like filler is 0.1 to 30% by mass based on the total mass of the liquid crystal polyester resin composition.

Examples of the inorganic particulate filler include silica, alumina, titanium oxide, glass beads, glass balloons, boron nitride, silicon carbide, and calcium carbonate.

Examples of the additives include additives generally used in resin compositions, for example, stabilizers, ultraviolet absorbers, plasticizers, flame retardants, flame retardant aids, antistatic agents, surfactants, colorants, lubricants, and the like. The content of the additive is 0.01-10% by mass relative to the total mass of the liquid crystal polyester resin composition.

Examples of the stabilizer include hindered phenols, hydroquinones, phosphites, and substituted products thereof.

Examples of the ultraviolet absorber include resorcinol, salicylate, benzotriazole, and benzophenone.

Examples of the colorant include dyes such as ニトロシン and pigments such as cadmium sulfide, phthalocyanine and carbon black.

Examples of the lubricant include stearic acid, montanic acid, half esters of stearic acid and fatty acids which are esters of montanic acid and polyhydric alcohols, stearyl alcohol, stearamide, and polyethylene wax.

The liquid crystal polyester resin composition of the present embodiment can be improved in molding processability by further adding a release agent. Examples of the mold release agent include montanic acid, montanic acid salts, montanic acid esters, full or half esters (also referred to as partial esters) of montanic acid polyols, stearyl alcohol, stearamides, full or partial esters of stearic acid and a polyol, and polyethylene waxes, and the like, and fatty acid esters of pentaerythritol are preferred, and esters of stearic acid and pentaerythritol are more preferred.

The amount of the release agent is preferably 0.1 to 0.5 parts by mass, more preferably 0.2 to 0.4 parts by mass, per 100 parts by mass of the liquid crystalline polyester. The amount of the release agent is 0.05 to 0.5% by mass, more preferably 0.1 to 0.4% by mass, based on the total mass of the liquid crystal polyester resin composition. When the amount of the release agent is within the above range, there is a tendency that contamination of the mold, protrusion of the molded article, and the like are hardly caused, and further, a mold-releasing effect can be obtained.

Examples of the resin other than the liquid crystal polyester resin include thermoplastic resins other than the liquid crystal polyester resin, such as polypropylene, polyamide, polyesters other than the liquid crystal polyester resin, polysulfone, polyethersulfone, polyphenylene sulfide, polyetherketone, polycarbonate, polyphenylene ether, and polyetherimide; and thermosetting resins such as phenol resins, epoxy resins, polyimide resins, and cyanate resins. The content of the resin other than the liquid crystal polyester resin is usually 0 to 20 parts by mass with respect to 100 parts by mass of the liquid crystal polyester resin.

< method for producing liquid crystal polyester resin composition >

The liquid crystal polyester resin composition is preferably prepared by melt-kneading a liquid crystal polyester resin, a filler (fibrous filler and plate-like filler) and other components used as needed using an extruder and extruding the mixture in the form of pellets.

As the extruder, one having a cylinder, one or more screws disposed in the cylinder, and one or more supply ports provided at one point of the cylinder is preferably used, and more preferably, one further having one or more exhaust ports provided at one point of the cylinder is used.

As described above, the configuration of the extruder used for melt kneading and the conditions for melt kneading may be changed so as to control the number average fiber length of the fibrous filler contained in the liquid crystal polyester resin composition to be in the range of 450 to 700 μm. Hereinafter, an example in which glass fibers are used as the fibrous filler will be described.

As a method for controlling the number average fiber length of the glass fibers contained in the liquid crystal polyester resin composition to be in the range of 450 μm or more and 700 μm or less, for example, a method in which two or more kinds of glass fibers having different fiber lengths are mixed in advance and supplied to an extruder is exemplified. In addition, as another method, there is a method in which one kind of glass fiber is supplied from a supply port on the upstream side of the extruder together with the liquid crystal polyester resin, and the other kind of glass fiber is supplied from a supply port on the downstream side.

For example, when the number average fiber length of the glass fibers contained in the liquid crystal polyester resin composition is controlled to be long, a method of mixing long fibers with more glass fibers than short fibers can be employed. As another method, a method of supplying long glass fibers from a downstream side supply port in the extruder, which has a short kneading time, can be used.

As the two or more types of glass fibers having different fiber lengths, for example, a combination of milled glass fibers and chopped strand glass fibers may be considered. Specifically, the fiber length of the milled glass fibers is preferably 30 to 500. mu.m. The chopped glass fibers preferably have a fiber length of 3mm to 4 mm.

Further, as a method of using two or more types of glass fibers having different fiber lengths, there are a method of mixing pellets of a liquid crystal polyester resin composition containing milled glass fibers and pellets of a liquid crystal polyester resin composition containing glass fibers of chopped glass fibers in advance and then supplying the mixture to an extruder, and a method of supplying one type of pellets from a supply port on the upstream side of the extruder and supplying the other type of pellets from a supply port on the downstream side.

Further, there is a method of adjusting the degree of breakage of the glass fiber by adjusting the shearing force applied to the glass fiber. Examples of the method of adjusting the shearing force include a method of changing the screw configuration and a method of controlling the number of revolutions of the screw and the cylinder temperature. This also makes it possible to adjust the melt viscosity of the molten resin.

The liquid-crystalline polyester resin composition thus obtained preferably has the following characteristics: the liquid crystal polyester resin composition is molded into a test piece of 127mm × 12.7mm × 6.4mmt according to ASTM D648, and when the deflection temperature under load measured under a load of 1.82MPa is measured, the deflection temperature under load of 260 ℃ or more and less than 285 ℃ is imparted.

When the deflection temperature under load is less than 285 ℃, the processing temperature at the time of molding can be reduced, and the change in the characteristics of the liquid crystal polyester resin composition depending on the thermal process at the time of molding can be suppressed. As a result, stress is less likely to concentrate during molding of the molded article, and warpage of the molded article is suppressed.

When the deflection temperature under load is 260 ℃ or higher, the rigidity and strength of the molded article can be sufficiently improved even at high temperatures. In addition, since the polymerization degree of the liquid crystal polyester resin in the molded article can be sufficiently increased, a molded article having high hardness can be obtained by using the liquid crystal polyester resin composition according to the embodiment of the present invention.

The liquid crystal polyester resin composition of the present embodiment preferably has the following characteristics: when the rockwell hardness of a test piece molded from the liquid crystal polyester resin composition is measured using the R scale according to ASTM D785, the rockwell hardness is imparted to 108 or more and 115 or less.

The liquid crystal polyester resin composition of the present embodiment preferably has the following characteristics: in the connector molded by the method described in the examples, the warpage amount of 0.1mm or less was given when the warpage amount was measured by the method described in the examples. The lower limit of the warpage amount is preferably smaller, and more preferably 0mm, for example.

According to the liquid crystal polyester resin composition having the above-mentioned structure, a liquid crystal polyester resin composition capable of producing a molded article having excellent sheet fluidity, small warpage and high hardness can be obtained.

< shaped body >

The molded article of the present embodiment uses the liquid crystal polyester resin composition as a material for forming the molded article.

The molding method of the liquid crystal polyester resin composition of the present embodiment is preferably a melt molding method.

Examples of the method include extrusion molding such as injection molding, T-die molding and inflation molding, compression molding, blow molding, vacuum molding and press molding. Among them, the injection molding method is preferable.

Examples of products or parts which are molded articles of the liquid crystal polyester resin composition include electric parts, electronic parts, and optical parts. Specific examples thereof include semiconductor manufacturing process-related components such as IMM, DDR, CPU socket, S/O, DIMM, Board-to-Board (Board to Board) connector, FPC connector, card connector, and the like, connector such as socket, relay box, relay base, relay gate, relay armature, and the like, relay component such as optical pickup bobbin, transformer bobbin, and the like, oscillator, printed circuit Board, semiconductor package, computer-related component, camera lens barrel, optical sensor housing, compact camera module housing (package, lens barrel), projector optical engine component, IC tray, wafer carrier, and the like; VTRs, televisions, irons, air conditioners, stereos, vacuum cleaners, refrigerators, electric cookers, lighting devices, and other household appliance components; lighting equipment components such as a lamp reflector, an LED reflector, a lamp bracket and the like; audio product parts such as an optical disk, a laser disk (registered trademark), and a speaker; optical cable ferrules, telephone parts, facsimile parts, modem and other communication equipment parts.

In addition, as examples other than these, there are copying machines and printer-related parts such as a separation claw and a heater holder; mechanical parts such as an impeller, a fan gear, a bearing, a motor part, and a case; automobile and vehicle-related components such as automobile mechanical components, various pipelines such as fuel-related, exhaust, intake systems, etc., exhaust gas, cooling water, various sensors for oil temperature systems, thermostat bases for air conditioners, motor insulators for air conditioners, brush holders for radiator motors, wiper motor-related components, distributors, engine switches, engine relays, transmission harnesses, air conditioner panel switch boards, coils for fuel-related solenoid valves, connectors for fuses, ECU connectors, horn terminals, electrical component insulating plates, lamp sockets, lamp reflectors, lamp housings, brake pistons, solenoid spools, engine oil filters, ignition device cases, etc.; cooking devices such as microwave cooking pots and heat-resistant tableware; materials for heat insulation or sound insulation such as floor materials and wall materials, support materials such as beams and columns, building materials such as roof materials, and materials for civil engineering and construction; parts for aircraft, spacecraft, space equipment; radiation facility members such as nuclear reactors; a marine facility component; a jig for washing; an optical device component; valves; a pipeline class; nozzles; a filter class; a film; medical equipment members, medical materials; a sensor-like component; a sanitary article; sporting goods; and leisure articles, etc.

The liquid crystal polyester resin composition of the present embodiment has excellent sheet fluidity and high hardness of a molded article. By utilizing such characteristics, the molded article obtained using the liquid crystal polyester resin composition of the present embodiment can be preferably used for sensors, bobbins, connectors, slots, relays, switches, and the like, and particularly, a member having a sheet portion of 0.2mm or less is preferably used for a connector.

According to the molded article having the above-mentioned structure, since the above-mentioned liquid crystal polyester resin composition is used, a molded article having high hardness can be obtained.

Another aspect of the liquid crystal polyester resin composition of the present invention is a liquid crystal polyester resin composition comprising a liquid crystal polyester resin and a filler composed of a fibrous filler and a plate-like filler, wherein the content of the filler is 33 parts by mass or more and 47 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester resin, the number-average fiber length of the fibrous filler is 450 μm or more and 590 μm or less, and the ratio (W1/W2) of the contained mass (W1) of the fibrous filler to the contained mass (W2) of the plate-like filler is 0.5 or more and 1.7 or less.

In the liquid crystal polyester resin composition, the plate-like filler may have a volume average particle diameter of 6 to 20 μm.

In the polyester resin composition, the liquid crystal polyester resin may be obtained by copolymerizing 4-hydroxybenzoic acid, terephthalic acid, isophthalic acid and 4,4 '-dihydroxybiphenyl as monomers, wherein the 4-hydroxybenzoic acid is 55 to 65 mol% based on the total moles of the monomers, the terephthalic acid is 10 to 17 mol% based on the total moles of the monomers, the isophthalic acid is 3 to 10 mol% based on the total moles of the monomers, and the 4, 4' -dihydroxybiphenyl is 15 to 25 mol% based on the total moles of the monomers.