WO2021029272A1

WO2021029272A1 - Liquid crystal polyester resin pellet, method for producing liquid crystal polyester resin pellet, and liquid crystal polyester resin molded body

Info

Publication number: WO2021029272A1
Application number: PCT/JP2020/029769
Authority: WO
Inventors: 翼田村; 貴之杉山
Original assignee: 住友化学株式会社
Priority date: 2019-08-09
Filing date: 2020-08-04
Publication date: 2021-02-18
Also published as: JP2021028375A; JP6741835B1; TW202122453A

Abstract

The present invention pertains to a liquid crystal polyester resin pellet containing a liquid crystal polyester and a pitch-based carbon fiber, wherein the melt viscosity at a shearing speed of 1,000 s^-1 is less than 10 Pa∙s at a temperature higher than the flow-starting temperature of the liquid crystal polyester by 60ºC, and the length-weighted average fiber length of the pitch-based carbon fiber is at least 100 μm.

Description

Liquid crystal polyester resin pellets, manufacturing method of liquid crystal polyester resin pellets, and liquid crystal polyester resin molded article

The present invention relates to a liquid crystal polyester resin pellet, a method for producing the liquid crystal polyester resin pellet, and a liquid crystal polyester resin molded product.
The present application claims priority based on Japanese Patent Application No. 2019-148161 filed in Japan on August 9, 2019, the contents of which are incorporated herein by reference.

Liquid crystal polyester is known to have high fluidity, heat resistance and dimensional accuracy. Liquid crystal polyesters are rarely used alone, and are used as liquid crystal polyester resin compositions containing a filler in order to satisfy the required characteristics (for example, bending characteristics and impact resistance) in various applications. It is known that a molded product made from such a liquid crystal polyester resin composition is lightweight and has high strength.

In recent years, in the field of transportation equipment including automobiles and aircraft, weight reduction of parts has been promoted for the purpose of improving fuel efficiency. In order to reduce the weight of parts, it is being considered to use a resin material instead of the current metal material for the material of each part. For example, by using the liquid crystal polyester resin composition as a molding material for a frame-based member or a suspension-based member for an automobile, an automobile that is lighter than the current product can be obtained.

However, the molded product obtained from the above-mentioned liquid crystal polyester resin composition has a problem that the mechanical properties are lower than those of the molded product obtained from the metal material.

Conventionally, in order to improve mechanical strength, heat resistance, particle resistance, etc., a liquid crystal polyester resin composition containing a liquid crystal polyester and a fibrous filler and a molded product obtained by using the liquid crystal polyester resin composition have been proposed ( For example, see Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-193270

Further weight reduction is required in the formation of molded bodies having a large proportion of the body weight, such as frame-based members and suspension-based members for automobiles. However, as the weight of the molded product is further reduced, securing the rigidity of the molded product becomes a problem.
In response to such a problem, the conventional method of simply mixing fibers with liquid crystal polyester as a filler cannot obtain the required flexural modulus of the molded product.

The present invention has been made in view of the above circumstances, and a liquid crystal polyester resin pellet capable of producing a molded product having an excellent flexural modulus, a method for producing a liquid crystal polyester resin pellet, and a liquid crystal polyester. An object of the present invention is to provide a resin molded product.

The present invention has the following aspects.
[1] A liquid crystal polyester resin pellet containing liquid crystal polyester and pitch-based carbon fibers.
The melt viscosity of the liquid crystal polyester at a shear rate of 1000s- ¹ at a flow start temperature of + 60 ° C. is less than 10 Pa · s.
A liquid crystal polyester resin pellet having a length-weighted average fiber length of 100 μm or more of the pitch-based carbon fibers.
Here, the flow start temperature is a melt viscosity of 4800 Pa when the resin heated at a temperature rising rate of 4 ° C./min is extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under a load of 9.81 MPa. -The temperature indicating s.
[2] The liquid crystal polyester resin pellet according to the above [1], wherein the content ratio of the pitch-based carbon fibers is 10 parts by mass to 100 parts by mass with respect to 100 parts by mass of the liquid crystal polyester.

[3] The liquid crystal polyester contains a repeating unit represented by the following formulas (1), (2), (3) or (4).
The content of the repeating unit represented by the following formula (1) is 30 mol% or more and 100 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). Is below
The content of the repeating unit represented by the following formula (2) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). Is below
The content of the repeating unit represented by the following formula (3) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). Is below
The content of the repeating unit represented by the following formula (4) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). The liquid crystal polyester resin pellet according to the above [1] or [2], which is as follows.

(1) -O-Ar ^1- CO-
(2) -CO-Ar ^2- CO-
(3) -CO-Ar ^3- CO-
(4) -O-Ar ^4- O-
(In formulas (1) to (4), Ar ¹ represents a 1,4-phenylene group or a 2,6-naphthylene group. Ar ² represents a 1,3-phenylene group or a 2,6-naphthylene group. Ar ³ represents a phenylene group (excluding 1,3-phenylene group), a naphthylene group (excluding 2,6-naphthylene group), or a biphenylene group. Ar ⁴ represents a phenylene group. , Naphthalene group, or biphenylene group.)
[4] The liquid crystal polyester resin according to any one of [1] to [3] above, wherein the melt viscosity of the liquid crystal polyester at a shear rate of 10000 s ^-1 at a flow start temperature of + 60 ° C. is less than 5 Pa · s. pellet.

[5] The liquid crystal polyester resin pellet according to any one of [1] to [4] above, wherein the pitch-based carbon fiber has a density of 2.10 g / cm ³ or more.
[6] The method for producing a liquid crystal polyester resin pellet according to any one of [1] to [5] above, which comprises a step of melt-kneading the liquid crystal polyester and the pitch-based carbon fiber.
[7] A liquid crystal polyester resin molded product containing liquid crystal polyester and pitch-based carbon fibers.
The melt viscosity of the liquid crystal polyester at a shear rate of 1000s- ¹ at a flow start temperature of + 60 ° C. is less than 10 Pa · s.
A liquid crystal polyester resin molded product having a length-weighted average fiber length of 100 μm or more of the pitch-based carbon fibers.
Here, the flow start temperature is a melt viscosity of 4800 Pa when the resin heated at a temperature rising rate of 4 ° C./min is extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under a load of 9.81 MPa. -The temperature indicating s.

According to the present invention, it is possible to provide a liquid crystal polyester resin pellet capable of producing a molded product having an excellent flexural modulus, a method for producing the liquid crystal polyester resin pellet, and a liquid crystal polyester resin molded product.

(Liquid crystal polyester resin pellets)
The liquid crystal polyester resin pellet of the present embodiment contains liquid crystal polyester and pitch-based carbon fibers.

In the present specification, a composition containing a thermoplastic resin containing a liquid crystal polyester and a fibrous filler is referred to as a "liquid crystal polyester resin composition". The molding material for producing a molded product obtained by granulating the liquid crystal polyester resin composition is referred to as "liquid crystal polyester resin pellets". A molded product obtained from a liquid crystal polyester resin composition or a liquid crystal polyester resin pellet is referred to as a “liquid crystal polyester resin molded product”.

Examples of the shape of the liquid crystal polyester resin pellet include, and are not limited to, columnar, disk-shaped, elliptical columnar, elliptical, gostone, spherical, and indefinite. Cylindrical is more preferable from the viewpoint of productivity and handling at the time of molding.

The liquid crystal polyester resin pellet of the present embodiment has a melt viscosity of less than 10 Pa · s at a shear rate of 1000 s ^-1 at a flow start temperature of the liquid crystal polyester of + 60 ° C., and the length-weighted average fiber length of the pitch-based carbon fibers. Is 100 μm or more. By using such liquid crystal polyester and pitch-based carbon fiber, the flexural modulus of the molded product produced from the liquid crystal polyester resin pellet of the present embodiment can be made excellent.

The liquid crystal polyester resin pellet of this embodiment is suitably used as a molding material for a molded product described later.

<Liquid crystal polyester>
The liquid crystal polyester resin pellet of the present embodiment contains a liquid crystal polyester.

The liquid crystal polyester used in the liquid crystal polyester resin pellets of the present embodiment preferably exhibits liquid crystal properties in a molten state, and the thermoplastic resin containing the liquid crystal polyester also exhibits liquid crystal properties in a molten state, and melts at a temperature of 450 ° C. or lower. It is preferable that the liquid crystal is used.
The liquid crystal polyester used in the present embodiment 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 used in the present embodiment is preferably a fully aromatic liquid crystal polyester using only an aromatic compound as a raw material monomer.

The melt viscosity of the liquid crystal polyester in the liquid crystal polyester resin pellet of the present embodiment at a shear rate of 1000 s ^-1 at a flow start temperature of + 60 ° C. is less than 10 Pa · s, preferably 9 Pa · s or less, more preferably 8 Pa · s or less. preferable. Since the melt viscosity at a shear rate of 1000 s ^-1 at a flow start temperature of + 60 ° C. is small, it is possible to suppress damage to the pitch-based carbon fibers during the processing process when the liquid crystal polyester resin pellets of the present embodiment are injection-molded. , It can be made excellent in mechanical strength such as bending elastic modulus. The melt viscosity of the liquid crystal polyester in the liquid crystal polyester resin pellet at a shear rate of 1000 s ^-1 at a flow start temperature of + 60 ° C. is preferably 1 Pa · s or more. That is, the melt viscosity of the liquid crystal polyester in the liquid crystal polyester resin pellet at a shear rate of 1000 s ^-1 at a flow start temperature of + 60 ° C. is preferably 1 Pa · s or more and less than 10 Pa · s, and is 1 Pa · s or more and 9 Pa · s. The following is more preferable, and 1 Pa · s or more and 8 Pa · s or less is further preferable.

The melt viscosity of the liquid crystal polyester in the liquid crystal polyester resin pellet of the present embodiment at a shear rate of 10000s ^-1 at a flow start temperature of + 60 ° C. is less than 5 Pa · s, preferably 4 Pa · s or less. Since the melt viscosity at a shear rate of 10000s ^-1 at a flow start temperature of + 60 ° C. is small, it is possible to suppress damage to the pitch-based carbon fibers during the processing process when the liquid crystal polyester resin pellets of the present embodiment are injection-molded. , It can be made excellent in mechanical strength such as bending elastic modulus. The melt viscosity of the liquid crystal polyester in the liquid crystal polyester resin pellet at a shear rate of 10000s- ¹ at a flow start temperature of + 60 ° C. is preferably 1 Pa · s or more. That is, the melt viscosity of the liquid crystal polyester in the liquid crystal polyester resin pellet at a shear rate of 10000s- ¹ at a flow start temperature of + 60 ° C. is preferably 1 Pa · s or more and less than 5 Pa · s, and is 1 Pa · s or more and 4 Pa · s. The following is more preferable.

The melt viscosity of the liquid crystal polyester can be determined by the following procedure. Using a capillary rheometer with a 0.5 mm in diameter × 10 mm of the capillary, the liquid crystal polyester after drying was placed in the capillary was set to a temperature of flow temperature + 60 ° C., a melt viscosity at a shear rate of 1000 s ^-1, and 10000s ^-1 To measure.

The melt viscosity of the liquid crystal polyester in the resin pellets can be measured as follows.
By using a single-screw extruder or a twin-screw extruder, resin pellets are melted in a cylinder at a temperature of 360 ° C. and extruded at a high pressure of 10 MPa or more through a mesh with an outlet of 10 μm to 50 μm or a die with a hole diameter of 50 μm. The liquid crystal polyertel and the fibrous filler of the pitch-based carbon fiber are separated. Using the obtained liquid crystal polyester, the melt viscosity can be measured in the same manner as the above-mentioned method for measuring the melt viscosity of the liquid crystal polyester.

The breakage rate of the pitch-based carbon fiber during the processing process (hereinafter, may be referred to as the breakage rate during the processing process) can be represented by the following formula (A1).
Damage rate during the processing process (%) = (1-L ₂ / L ₁ ) x 100 ... (A1)
Here, L ₁ is the length-weighted average fiber length of the fibrous filler in the resin pellet, and L ₂ is the length-weighted average fiber length of the fibrous filler in the molded body.

When the liquid crystal polyester resin pellet is injection-molded, it is preferable that the damage rate during the processing process is small. The liquid crystal polyester resin pellet of the present embodiment has a melt viscosity of less than 10 Pa · s at a shear rate of 1000 s ^-1 at a flow start temperature of + 60 ° C. As a result, when the liquid crystal polyester resin pellet is injection-molded, the damage rate during the processing process can be easily set to 26% or less, 24% or less, and 23% or less. , 22% or less, and 20% or less.

A typical example of the liquid crystal polyester used in the present embodiment is at least one compound selected from the group consisting of aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, aromatic hydroxyamine and aromatic diamine. Is selected from the group consisting of those obtained by polymerizing (hypercondensation) with, those obtained by polymerizing multiple kinds of aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids and aromatic diols, aromatic hydroxyamines and aromatic diamines. Examples thereof include those obtained by polymerizing at least one compound, and those obtained by polymerizing a polyester such as polyethylene terephthalate and an aromatic hydroxycarboxylic acid. Here, the aromatic hydroxycarboxylic acid, the aromatic dicarboxylic acid, the aromatic diol, the aromatic hydroxyamine, and the aromatic diamine are independently used in place of a part or all of them, and a polymerizable derivative thereof is used. May be good.

Examples of polymerizable derivatives of compounds having a carboxyl group, such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids, are those obtained by converting a carboxyl group into an alkoxycarbonyl group or an aryloxycarbonyl group (ester), carboxyl. Examples thereof include those obtained by converting a group into a haloformyl group (acid halide) and those obtained by converting a carboxyl group into an acyloxycarbonyl group (acid anhydride). Examples of polymerizable derivatives of compounds having a hydroxyl group, such as aromatic hydroxycarboxylic acids, aromatic diols and aromatic hydroxyamines, are those obtained by acylating a hydroxyl group into an acyloxyl group (acylated product). ). Examples of polymerizable derivatives of compounds having an amino group, such as aromatic hydroxyamines and aromatic diamines, include those obtained by acylating an amino group and converting it into an acylamino group (acylated product).

The liquid crystal polyester used in the present embodiment has a repeating unit represented by the following formula (1) (hereinafter, may be referred to as a “repetition unit (1)”) and a repeating unit represented by the following formula (2) ( Hereinafter, it may be referred to as "repetition unit (2)"), a repetition unit represented by the following formula (3) (hereinafter, may be referred to as "repetition unit (3)"), or the following formula (4). ) Is included (hereinafter, may be referred to as “repetition unit (4)”).
The content of the repeating unit (1) with respect to the total amount of the repeating units (1), (2), (3) and (4) is 30 mol% or more and 100 mol% or less.
The content of the repeating unit (2) with respect to the total amount of the repeating units (1), (2), (3) and (4) is 0 mol% or more and 35 mol% or less.
The content of the repeating unit (3) with respect to the total amount of the repeating units (1), (2), (3) and (4) is 0 mol% or more and 35 mol% or less.
The content of the repeating unit (4) with respect to the total amount of the repeating units (1), (2), (3) and (4) is preferably 0 mol% or more and 35 mol% or less.

(1) -O-Ar ^1- CO-
(2) -CO-Ar ^2- CO-
(3) -CO-Ar ^3- CO-
(4) -O-Ar ^4- O-

(In formulas (1) to (4), Ar ¹ represents a 1,4-phenylene group or a 2,6-naphthylene group. Ar ² represents a 1,3-phenylene group or a 2,6-naphthylene group. Ar ³ represents a phenylene group (excluding 1,3-phenylene group), a naphthylene group (excluding 2,6-naphthylene group), or a biphenylene group. Ar ⁴ represents a phenylene group. , Naphthalene group, or biphenylene group.)

The repeating unit (1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid. As the repeating unit (1), Ar ¹ is a p-phenylene group (repeating unit derived from p-hydroxybenzoic acid), or Ar ¹ is a 2,6-naphthylene group (6-hydroxy-2). -A repeating unit derived from naphthoic acid) is preferable, and ^{one in} which Ar ¹ is a p-phenylene group (that is, a 1,4-phenylene group) is more preferable.
In the present specification, the term "origin" means that the chemical structure of the functional group that contributes to the polymerization changes due to the polymerization of the raw material monomer, and no other structural change occurs.

The repeating unit (2) and the repeating unit (3) are repeating units derived from a predetermined aromatic dicarboxylic acid. As the repeating unit (2), Ar ² is a 1,3-phenylene group (repeating unit derived from isophthalic acid), or Ar ² is a 2,6-naphthylene group (2,6-naphthalene). It is a repeating unit derived from dicarboxylic acid). As the repeating unit (3), Ar ³ is a phenylene group (excluding 1,3-phenylene group) (repeating unit derived from phthalic acid), and Ar ³ is a naphthylene group (however, 2, 6). -A naphthylene group is excluded (repetition unit derived from naphthalene dicarboxylic acid), or Ar ³ is a biphenylene group (repetition unit derived from dicarboxybiphenyl), and Ar ³ is 1,4. -A phenylene group (repetitive unit derived from terephthalic acid) or one in which Ar ³ is a 4,4'-biphenylene group (repetitive unit derived from 4,4'-biphenyldicarboxylic acid) is preferable.

The repeating unit (4) is a repeating unit derived from a predetermined aromatic diol. As the repeating unit (4), Ar ⁴ is a p-phenylene group (repeating unit derived from hydroquinone), or Ar ⁴ is a 4,4'-biphenylene group (4,4'-dihydroxybiphenyl). Derived repeating unit) is preferred.

The content of the repeating unit (1) is the total amount of all repeating units (by dividing the mass of each repeating unit constituting the liquid crystal polyester resin by the formula amount of each repeating unit, the amount equivalent to the amount of substance of each repeating unit ( Mol) is determined, and the total value thereof) is preferably 30 mol% or more and 100 mol% or less, more preferably 30 mol% or more and 90 mol% or less, and further preferably 40 mol% or more and 80 mol% or less. Especially preferably 50 mol% or more and 70 mol% or less.

The content of the repeating unit (2) is preferably 0 mol% or more and 35 mol% or less, more preferably 6 mol% or more and 30 mol% or less, and 7 mol% or more and 20 mol% with respect to the total amount of all repeating units. The following is more preferable, and 8 mol% or more and 17.5 mol% or less are particularly preferable.

The content of the repeating unit (3) is preferably 0 mol% or more and 35 mol% or less, more preferably 3 mol% or more and 30 mol% or less, and 4 mol% or more and 20 mol% with respect to the total amount of all repeating units. The following is more preferable, and 5 mol% or more and 12 mol% or less is particularly preferable.

The content of the repeating unit (4) is preferably 0 mol% or more and 35 mol% or less, more preferably 10 mol% or more and 35 mol% or less, and 15 mol% or more and 30 mol% with respect to the total amount of all repeating units. The following is more preferable, and 17.5 mol% or more and 27.5 mol% or less are particularly preferable. However, the total amount of the repeating units (1), (2), (3) and (4) does not exceed 100 mol%.

The higher the content of the repeating unit (1), the easier it is to improve the melt fluidity, heat resistance, strength and rigidity, but if it is too high, the melt temperature and melt viscosity tend to increase, and the temperature required for molding increases. easy.

The ratio of the total content of the repeating unit (2) and the repeating unit (3) to the content of the repeating unit (4) is [content of repeating unit (2) + content of repeating unit (3)] / [ The content of the repeating unit (4)] (mol / mol) is preferably 0.9 / 1 to 1 / 0.9, more preferably 0.95 / 1 to 1 / 0.95, and 0.98. It is more preferably 1/1 to 1 / 0.98.

The liquid crystal polyester used in the present embodiment may have two or more repeating units (1) to (4) independently of each other. Further, the liquid crystal polyester may have a repeating unit other than the repeating units (1) to (4), but the content thereof is preferably 10 mol% or less with respect to the total amount of all repeating units. More preferably, it is mol% or less.

The liquid crystal polyester used in the present embodiment is obtained by melt-polymerizing a raw material monomer corresponding to a repeating unit constituting the liquid crystal polyester, and solid-phase polymerizing the obtained polymer (hereinafter, may be referred to as “prepolymer”). It is preferable to manufacture the product. As a result, a high molecular weight liquid crystal polyester having high heat resistance, strength and rigidity can be produced with good operability. The melt polymerization may be carried out in the presence of a catalyst, and examples of this catalyst include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate and antimony trioxide. , 4- (Dimethylamino) pyridine, 1-methylimidazole and the like, and the nitrogen-containing heterocyclic compound is mentioned, and the nitrogen-containing heterocyclic compound is preferably used.

The flow start temperature of the liquid crystal polyester used in the present embodiment is preferably 280 ° C. or higher, more preferably 280 ° C. or higher and 400 ° C. or lower, and further preferably 280 ° C. or higher and 380 ° C. or lower.
The higher the flow start temperature of the liquid crystal polyester used in the present embodiment, the more the heat resistance, strength and rigidity of the liquid crystal polyester tend to improve. On the other hand, when the flow start temperature of the liquid crystal polyester exceeds 400 ° C., the melting temperature and the melting viscosity of the liquid crystal polyester tend to increase. Therefore, the temperature required for molding the liquid crystal polyester tends to increase.

In the present specification, the flow start temperature of the liquid crystal polyester is also referred to as a flow temperature or a flow temperature, and is a temperature that serves as a guideline for the molecular weight of the liquid crystal polyester (edited by Naoyuki Koide, "Liquid Crystal Polymer-Synthesis / Molding / Application-". , CMC Co., Ltd., June 5, 1987, p.95). The flow start temperature is such that the liquid crystal polyester is melted while raising the temperature at a rate of 4 ° C./min under a load of 9.81 MPa (100 kg / cm ² ) using a capillary rheometer, and is melted from a nozzle having an inner diameter of 1 mm and a length of 10 mm. It is a temperature showing a viscosity of 4800 Pa · s (48000 poisons) when extruded.

The content ratio of the liquid crystal polyester with respect to 100% by mass of the thermoplastic resin is preferably 80% by mass or more and 100% by mass or less, more preferably 85% by mass or more and 100% by mass or less, and 90% by mass or more and 100% by mass. It is particularly preferable that it is mass% or less.

The content ratio of the liquid crystal polyester is preferably 50 to 90.9% by mass, more preferably 50 to 87% by mass, still more preferably 50 to 85% by mass, and 50 by mass with respect to 100% by mass of the liquid crystal polyester resin pellets. It is more preferably -80% by mass, further preferably 50 to 72% by mass, still more preferably 50 to 63% by mass.

When the content ratio of the liquid crystal polyester is equal to or higher than the above lower limit value, the bending elastic modulus of the test piece produced by using the liquid crystal polyester resin pellet of the present embodiment can be improved.

<Pitch carbon fiber>
The liquid crystal polyester resin pellet of the present embodiment contains pitch-based carbon fibers.

The density of the pitch-based carbon fibers in the liquid crystal polyester resin pellet of the present embodiment is preferably 2.10 g / cm ³ or more. Preferably the density of the pitch-based carbon fiber is 2.11 g / cm ³ or more, more preferably 2.12 g / cm ³ or more, particularly preferably 2.13 g / cm ³ or more. Preferably the density of the pitch-based carbon fibers is less than 2.25 g / cm ^3, more preferably 2.22 g / cm ³ or less, particularly preferably 2.20 g / cm ³ or less. That is, the density of the pitch-based carbon fiber of the liquid crystal polyester resin pellets is preferably at most 2.10 g / cm ³ or more ^{2.25g / cm 3, 2.11g / cm} 3 or more 2.22 g / cm ³ or less more preferably, more preferably at most 2.12 g / cm ³ or more 2.20 g / cm ^3, even more preferably at most 2.13 g / cm ³ or more 2.20 g / cm ^3.

The density of the pitch-based carbon fibers in the liquid crystal polyester resin pellets is determined by dissolving the liquid crystal polyester in the liquid crystal polyester resin pellets with, for example, a mixed solution of triethylene glycol and monoethanolamine at a ratio of 4: 1. After collecting the sample of, it can be measured using a specific gravity bottle.

The pitch-based carbon fibers in the liquid crystal polyester resin pellet of the present embodiment have a length-weighted average fiber length of 100 μm or more. The length-weighted average fiber length of the pitch-based carbon fibers is preferably 120 μm or more, and more preferably 140 μm or more. Length of pitch-based carbon fibers in the liquid crystal polyester resin pellet of the present embodiment When the liquid crystal polyester resin pellet is injection-molded by setting the weighted average fiber length to the above lower limit value or more, the pitch in the liquid crystal polyester resin molded body. The length-weighted average fiber length of the system carbon fibers can be easily adjusted to 100 μm or more, and it becomes easy to mold a molded product having an excellent bending elasticity. The length-weighted average fiber length of the pitch-based carbon fibers is preferably less than 5 mm, more preferably 2 mm or less, further preferably 1 mm or less, and particularly preferably 500 μm or less. That is, the length-weighted average fiber length of the pitch-based carbon fibers in the liquid crystal polyester resin pellet is preferably 100 μm or more and less than 5 mm, more preferably 120 μm or more and 2 mm or less, and 140 μm or more and 1 mm or less. More preferably, it is 140 μm or more and 500 μm or less.

The length-weighted average fiber length of the fibrous filler in the liquid crystal polyester resin pellet can be obtained by the following procedure. First, the test sample of the liquid crystal polyester resin pellet is sintered to remove the resin component and leave only the fibrous filler. Next, the fibrous filler is dispersed in an aqueous solution containing a surfactant to prepare a fibrous filler dispersion. By observing the fibrous filler dispersion with a microscope and measuring the length of more than 500 fibers, the length of the fibrous filler in the liquid crystal polyester resin pellet is weighted average fiber length lm = (Σli ² × ni) / Find (Σli × ni).
li: Fiber length of fibrous filler ni: Number of fibrous fillers of fiber length li

The tensile strength of the pitch-based carbon fiber is preferably 2000 MPa or more, more preferably 2500 MPa or more, and further preferably 3000 MPa or more. Further, by using the pitch-based carbon fiber having high tensile strength, the fiber breakage during the processing process up to the production of the molded product is suppressed, and the fiber can be left for a long time, so that the effect of the invention can be easily obtained.
The tensile strength of the pitch-based carbon fiber means a value measured in accordance with JIS R 7606: 2000.

Pitch-based carbon fibers can be mainly classified into mesophase pitch-based carbon fibers using mesophase pitch as a starting material and isotropic pitch-based carbon fibers using isotropic pitch as a starting material. From the viewpoint of obtaining high mechanical properties, mesophase pitch carbon fibers are preferably used.

The tensile elastic modulus of the pitch-based carbon fiber is preferably 200 GPa or more, more preferably 250 GPa or more, further preferably 500 GPa or more, and particularly preferably 650 GPa or more. By using highly elastic pitch-based carbon fiber, the elastic modulus of the molded product can be improved. It becomes easy to obtain the effect of the invention. The tensile elastic modulus of pitch-based carbon fibers can be measured in accordance with JIS R 7606: 2000.

Examples of the form of pitch-based carbon fiber include roving, chopped fiber, and milled fiber. The forms of these pitch-based carbon fibers may be used alone or in combination of two or more. Chopped fibers are preferred because they are easy to handle and the length-weighted average fiber length can be easily controlled.

Examples of pitch-based carbon fibers include "Dialed (registered trademark)" manufactured by Mitsubishi Chemical Corporation, "GRANOC (registered trademark)" manufactured by Nippon Graphite Fiber Co., Ltd., and "Donna Carbo (registered trademark)" manufactured by Osaka Gas Chemical Corporation. , "Kureka (registered trademark)" manufactured by Kureha Co., Ltd., etc. Examples of the mesophase pitch carbon fiber include "Dialed (registered trademark)" manufactured by Mitsubishi Chemical Corporation and "GRANOC (registered trademark)" manufactured by Nippon Graphite Fiber Co., Ltd. It is preferable to use the mesophase pitch carbon fiber because the mechanical properties of the molded product can be improved.

The number average fiber diameter of the pitch-based carbon fibers in the liquid crystal polyester resin pellet of the present embodiment is not particularly limited, but is preferably 1 μm to 40 μm, preferably 3 μm to 35 μm, and 1 μm to 25 μm. Is more preferable, and it is more preferably 3 μm to 20 μm, and even more preferably 5 μm to 15 μm.

For the number average fiber diameter of the pitch-based carbon fibers, the number average value of the values obtained by observing the pitch-based carbon fibers with a microscope (500 times) and measuring the fiber diameters of 500 pitch-based carbon fibers is adopted.
When the number average fiber diameter of the pitch-based carbon fibers is at least the lower limit of the above-mentioned preferable range, the pitch-based carbon fibers are likely to be dispersed in the liquid crystal polyester resin pellets. In addition, it is easy to handle pitch-based carbon fibers when manufacturing liquid crystal polyester resin pellets. On the other hand, when it is not more than the upper limit value of the above preferable range, the liquid crystal polyester is efficiently strengthened by the pitch-based carbon fibers. Therefore, an excellent flexural modulus can be imparted to the molded product obtained by molding the liquid crystal polyester resin pellets of the present embodiment.

As the pitch-based carbon fiber, one treated with a sizing agent may be used.
Pitch-based carbon fibers that have not been treated with a sizing agent can be preferably used because of their interfacial adhesiveness and the fact that voids are less likely to occur in the produced molded product.

The sizing agent in the present invention is not particularly limited, and examples thereof include nylon-based polymers, polyether-based polymers, epoxy-based polymers, ester-based polymers, urethane-based polymers, mixed polymers thereof, and modified polymers thereof. Further, a so-called silane coupling agent such as aminosilane or epoxysilane, or a known coupling agent such as a titanium coupling agent can also be used.

When the pitch-based carbon fiber is chopped fiber, the number of single yarns is preferably 10,000 or more and 100,000 or less, more preferably 10,000 or more and 50,000 or less, and 10,000 or more and 30,000 or less from the viewpoint of economy and handleability at the time of production. Is even more preferable.

The content ratio of the pitch-based carbon fibers in the liquid crystal polyester resin pellet of the present embodiment is preferably 10 to 100 parts by mass, more preferably 15 to 100 parts by mass, and 18 to 100 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. 100 parts by mass is further preferable, 25 to 100 parts by mass is further preferable, 40 to 100 parts by mass is further preferable, and 60 to 100 parts by mass is further preferable.

The content ratio of the pitch-based carbon fibers is preferably 9.1 to 50% by mass, more preferably 13 to 50% by mass, still more preferably 15 to 50% by mass, based on 100% by mass of the liquid crystal polyester resin pellets. , 20 to 50% by mass, more preferably 28 to 50% by mass, still more preferably 37 to 50% by mass.

If the content ratio of the pitch-based carbon fibers is equal to or higher than the lower limit of the above-mentioned preferable range, the effect of improving the flexural modulus by the pitch-based carbon fibers can be easily enhanced. On the other hand, if it is not more than the upper limit of the above-mentioned preferable range, the pitch-based carbon fibers can be quantitatively supplied, and the productivity of the resin pellets is improved.

<Other ingredients>
The liquid crystal polyester resin pellet of the present embodiment contains, as a raw material, other components such as the above-mentioned liquid crystal polyester and pitch-based carbon fiber, and if necessary, a thermoplastic resin other than the liquid crystal polyester, a filler, and an additive. It may contain more than seeds.

Examples of resins other than liquid crystal polyester contained in liquid crystal polyester resin pellets include polyolefin resins such as polypropylene, polybutadiene, and polymethylpentene, vinyl resins such as vinyl chloride, vinylidene chloride acetate, and polyvinyl alcohol, polystyrene, and acrylonitrile-styrene. Polyamide resin such as resin (AS resin), acrylonitrile-butadiene-styrene resin (ABS resin), polyamide 6 (nylon 6), polyamide 66 (nylon 66), polyamide 11 (nylon 11), polyamide 12 (nylon 12), Polyamide 46 (Nylon 46), Polyamide 610 (Nylon 610), Polytetramethylene terephthalamide (Nylon 4T), Polyhexamethylene terephthalamide (Nylon 6T), Polymethaxylylene adipamide (Nylon MXD6), Polynonamethylene terephthalamide Polyamide resin such as (nylon 9T), polydecamethylene terephthalamide (nylon 10T), polyester resin other than liquid crystal polyester such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, modified polysulfone, polyether Polysulfone-based resins such as sulfone, polysulfone, and polyphenylsulfone, polyphenylene sulfide-based resins such as linear polyphenylene sulfide, crosslinked polyphenylene sulfide, and semi-crosslinked polyphenylene sulfide, polyetherketone, polyetheretherketone, polyetherketoneketone, etc. Examples thereof include polyimide resins such as polyetherketone resin, thermoplastic polyimide, polyamideimide and polyetherimide, and thermoplastic resins such as polycarbonate and polyphenylene ether.

The filler may be a plate-shaped filler, a spherical filler, or other granular filler. Further, the filler may be an inorganic filler or an organic filler.

Examples of plate-like inorganic fillers include talc, mica, graphite, wollastonite, glass flakes, barium sulfate, and calcium carbonate. The mica may be muscovite, phlogopite, fluorine phlogopite, or tetrasilicon mica.

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

Examples of additives include flame retardants, conductivity-imparting agents, crystal nucleating agents, UV absorbers, antioxidants, vibration damping agents, antibacterial agents, insect repellents, deodorants, anticoloring agents, heat stabilizers, and release agents. Examples include molds, antistatic agents, plasticizers, lubricants, colorants, pigments, dyes, foaming agents, antifoaming agents, viscosity modifiers and surfactants.

The melt viscosity of the liquid crystal polyester in the liquid crystal polyester resin pellet of the present embodiment at a flow start temperature of + 60 ° C. at a shear rate of 1000 s ^-1 is less than 10 Pa · s, and the length-weighted average fiber length of the pitch-based carbon fibers. Is 100 μm or more.
The melt viscosity at a shear rate of 1000 s ^-1 at a flow start temperature of + 60 ° C. of the liquid crystal polyester in the liquid crystal polyester resin pellet of the present embodiment is 1 Pa · s or more and less than 10 Pa · s, and the length of the pitch-based carbon fiber. The weighted average fiber length is preferably 120 μm or more and 2 mm or less.
The melt viscosity at a shear rate of 1000 s ^-1 at a flow start temperature of + 60 ° C. of the liquid crystal polyester in the liquid crystal polyester resin pellet of the present embodiment is 1 Pa · s or more and 9 Pa · s or less, and the length of the pitch-based carbon fiber. More preferably, the weighted average fiber length is 140 μm or more and 1 mm or less.
The melt viscosity at a shear rate of 1000 s ^-1 at a flow start temperature of + 60 ° C. of the liquid crystal polyester in the liquid crystal polyester resin pellet of the present embodiment is 1 Pa · s or more and 8 Pa · s or less, and the length of the pitch-based carbon fiber. The weighted average fiber length is 140 μm or more and 500 μm or less, which is particularly preferable.
The melt viscosity of the liquid crystal polyester in the liquid crystal polyester resin pellet of the present embodiment at a flow start temperature of + 60 ° C. at a shear rate of 1000 s ^-1 is 5 Pa · s or more and 8 Pa · s or less, and the length of the pitch-based carbon fiber. The weighted average fiber length may be 155 μm or more and 280 μm or less.

The liquid crystal polyester resin pellet of the present invention has the following aspects.
"1" A liquid crystal polyester resin pellet containing liquid crystal polyester and pitch-based carbon fibers.
The melt viscosity of the liquid crystal polyester at a shear rate of 1000s- ¹ at a flow start temperature of + 60 ° C. is less than 10 Pa · s.
A liquid crystal polyester resin pellet having a length-weighted average fiber length of 100 μm or more of the pitch-based carbon fibers.
Here, the flow start temperature is a melt viscosity of 4800 Pa when the resin heated at a temperature rising rate of 4 ° C./min is extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under a load of 9.81 MPa. -The temperature indicating s.
"2" The content ratio of the pitch-based carbon fiber is 10 parts by mass to 100 parts by mass, preferably 15 parts by mass to 100 parts by mass, and more preferably 18 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. It is 10 parts by mass to 100 parts by mass, more preferably 25 parts by mass to 100 parts by mass, further preferably 40 parts by mass to 100 parts by mass, and further preferably 60 parts by mass to 100 parts by mass. The liquid crystal polyester resin pellet described in the above.

"3" The liquid crystal polyester contains a repeating unit represented by the following formulas (1), (2), (3) or (4).
The content of the repeating unit represented by the following formula (1) is 30 mol% or more and 100 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). It is preferably 30 mol% or more and 90 mol% or less, more preferably 40 mol% or more and 80 mol% or less, and further preferably 50 mol% or more and 70 mol% or less.
The content of the repeating unit represented by the following formula (2) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). It is preferably 6 mol% or more and 30 mol% or less, more preferably 7 mol% or more and 20 mol% or less, and further preferably 8 mol% or more and 17.5 mol% or less.
The content of the repeating unit represented by the following formula (3) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). It is preferably 3 mol% or more and 30 mol% or less, more preferably 4 mol% or more and 20 mol% or less, and further preferably 5 mol% or more and 12 mol% or less.
The content of the repeating unit represented by the following formula (4) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). The above, preferably 10 mol% or more and 35 mol% or less, more preferably 15 mol% or more and 30 mol% or less, still more preferably 17.5 mol% or more and 27.5 mol% or less. The liquid crystal polyester resin pellet according to "1" or "2". However, the total amount of the repeating units represented by the formulas (1), (2), (3) and (4) does not exceed 100 mol%.

(1) -O-Ar ^1- CO-
(2) -CO-Ar ^2- CO-
(3) -CO-Ar ^3- CO-
(4) -O-Ar ^4- O-
(In formulas (1) to (4), Ar ¹ represents a 1,4-phenylene group or a 2,6-naphthylene group. Ar ² represents a 1,3-phenylene group or a 2,6-naphthylene group. Ar ³ represents a phenylene group (excluding 1,3-phenylene group), a naphthylene group (excluding 2,6-naphthylene group), or a biphenylene group. Ar ⁴ represents a phenylene group. , Naphthalene group, or biphenylene group.)

"4" The content of the repeating unit represented by the formula (1) is 30 mol% or more and 90 mol with respect to the total amount of the repeating unit represented by the formulas (1), (2), (3) and (4). % Or less
When the content of the repeating unit represented by the formula (2) is 6 mol% or more and 30 mol% or less with respect to the total amount of the repeating units represented by the formulas (1), (2), (3) and (4). Yes,
When the content of the repeating unit represented by the formula (3) is 3 mol% or more and 30 mol% or less with respect to the total amount of the repeating units represented by the formulas (1), (2), (3) and (4). Yes,
When the content of the repeating unit represented by the formula (4) is 10 mol% or more and 35 mol% or less with respect to the total amount of the repeating units represented by the formulas (1), (2), (3) and (4). The liquid crystal polyester resin pellet according to the above "3". However, the total amount of the repeating units represented by the formulas (1), (2), (3) and (4) does not exceed 100 mol%.
"5" The melt viscosity of the liquid crystal polyester at a shear rate of 10000s- ¹ at a flow start temperature of + 60 ° C. is 1 Pa · s or more and less than 5 Pa · s, preferably 1 Pa · s or more and 4 Pa · s or less. The liquid crystal polyester resin pellet according to any one of "1" to "4".

"6" density of the pitch-based carbon fiber is at 2.10 g / cm ³ or more 2.25 g / cm ³ or less, preferably not more than 2.11 g / cm ³ or more 2.22 g / cm ^3, more preferably 2.12 g / cm ³ or more 2.20 g / cm ³ or less, further preferably 2.13 g / cm ³ or more 2.20 g / cm ³ or less, any one of the "1" to "5" Liquid crystal polyester resin pellets described in.

"7" The flow start temperature of the liquid crystal polyester is 280 ° C. or higher, preferably 280 ° C. or higher and 400 ° C. or lower, and more preferably 280 ° C. or higher and 380 ° C. or lower, as described in "1" to "6". The liquid crystal polyester resin pellet according to any one item.

"8" The length-weighted average fiber length of the pitch-based carbon fiber is 100 μm or more and less than 5 mm, preferably 120 μm or more and 2 mm or less, more preferably 140 μm or more and 1 mm or less, and further preferably 140 μm or more and 500 μm or less. The liquid crystal polyester resin pellet according to any one of "1" to "7", which is particularly preferably 155 μm or more and 280 μm or less.

"9" The melt viscosity of the liquid crystal polyester at a flow start temperature of + 60 ° C. at a shear rate of 1000 s ^-1 is 1 Pa · s or more and less than 10 Pa · s, preferably 1 Pa · s or more and 9 Pa · s or less, more preferably. The liquid crystal polyester resin pellet according to any one of "1" to "8", wherein is 1 Pa · s or more and 8 Pa · s or less, and more preferably 5 Pa · s or more and 8 Pa · s or less.

"10" A liquid crystal polyester resin pellet containing a thermoplastic resin containing a liquid crystal polyester and a fibrous filler.
The content ratio of the liquid crystal polyester with respect to 100% by mass of the thermoplastic resin is 80% by mass or more and 100% by mass or less, preferably 85% by mass or more and 100% by mass or less, and more preferably 90% by mass or more and 100% by mass or less. The liquid crystal polyester resin pellet according to any one of "1" to "9" below.

(Manufacturing method of liquid crystal polyester resin pellets)
The method for producing the liquid crystal polyester resin pellet of the present embodiment includes a step of melt-kneading the liquid crystal polyester and the pitch-based carbon fiber.

The temperature of melt kneading is appropriately determined according to the type of liquid crystal polyester, and is preferably set to a temperature 60 ° C. higher than the flow start temperature of the liquid crystal polyester used. Above the above temperature, the liquid crystal polyester starts to decompose, and the strands are broken by the decomposition gas, so that the productivity is lowered. In addition, the entry of gas into the pellets deteriorates the mechanical properties of the molded product to be produced. On the other hand, if melt-kneaded at a temperature lower than 60 ° C., the pitch-based carbon fibers contained therein may be broken and the effects of the invention may not be obtained.

Pitch-based carbon fibers are preferably 10 parts by mass to 100 parts by mass, more preferably 15 parts by mass to 100 parts by mass, based on 100 parts by mass of liquid crystal polyester, depending on the characteristics required for the liquid crystal polyester resin pellets. More preferably, 18 parts by mass to 100 parts by mass, still more preferably 25 parts by mass to 100 parts by mass, still more preferably 40 parts by mass to 100 parts by mass, still more preferably 60 parts by mass to 100 parts by mass is melt-kneaded. When the blending amount of the pitch-based carbon fibers is at least the lower limit of the above-mentioned preferable range, the adhesion between the liquid crystal polyester and the pitch-based carbon fibers is likely to be enhanced. On the other hand, if it is not more than the upper limit of the above-mentioned preferable range, the pitch-based carbon fibers can be quantitatively supplied, and the productivity of the resin pellets is improved.

The method for producing the liquid crystal polyester resin pellet of the present embodiment includes a step of cooling the melt-kneaded liquid crystal polyester resin composition to obtain a strand-shaped resin structure and a step of cutting the strand-shaped resin structure. , Are preferably included.

The melt-kneaded liquid crystal polyester resin composition is taken up according to a conventional method, cooled to, for example, 50 to 150 ° C., and then a strand-shaped resin structure is cut to a desired length in the longitudinal direction thereof to obtain a liquid crystal polyester. Make resin pellets. The cooling time is not particularly limited, but is, for example, 3 to 30 seconds.

Liquid crystal polyester resin pellets are pitch-based carbon fibers hardened with a thermoplastic resin containing liquid crystal polyester. The length of the liquid crystal polyester resin pellet produced in the present embodiment is, for example, 1 mm or more and less than 50 mm, and may be 1.5 mm to 48 mm or 2 mm to 46 mm.

Examples of the method for producing the liquid crystal polyester resin pellets include a method in which the liquid crystal polyester and the pitch-based carbon fibers are dry-blended and then melt-kneaded; a method in which the pitch-based carbon fibers are supplied to the melted liquid crystal polyester resin.
In particular, since the dispersibility and length-weighted average fiber length of the pitch-based carbon fibers can be controlled and the effects of the present invention can be obtained, a method of supplying the pitch-based carbon fibers to the molten liquid crystal polyester resin is preferable. Specifically, the liquid crystal polyester resin may be supplied from the main raw material feeder installed upstream of the extruder, melt-kneaded, and then the pitch-based carbon fibers may be supplied from the side feeder installed downstream of the extruder.

An extruder may be used for melt kneading to produce the liquid crystal polyester resin pellets.
Examples of the extruder include a single-screw extruder and a twin-screw extruder, and a twin-screw extruder can be preferably used from the viewpoint of productivity.

In the case of a twin-screw extruder, the screw rotation speed of the extruder is preferably 50 rpm or more and less than 200 rpm. When the screw rotation speed of the extruder is 50 rpm or more, the dispersibility of the pitch-based carbon fibers is excellent. Further, when the screw rotation speed of the extruder is less than 200 rpm, breakage of the pitch-based carbon fibers can be suppressed.

When supplying pitch-based carbon fibers to molten liquid crystal polyester, the screw of the extruder is preferably provided with one or more kneading zones before the supply of pitch-based carbon fibers. By providing the kneading zone before feeding, the viscosity of the liquid crystal polyester is lowered due to the influence of shearing by the kneading element, and the dispersibility of the pitch-based carbon fibers and the length-weighted average fiber length can be controlled. If the kneading zone is provided after the supply, the pitch-based carbon fibers may be broken due to shearing in the kneading zone, and it may be difficult to control the length-weighted average fiber length.

The cut length of the pitch-based carbon fibers used in the production of the liquid crystal polyester resin pellets is preferably 2 mm or more and 25 mm or less, preferably 3 mm or more, from the viewpoint of easy quantitative supply and controllability of the length-weighted average fiber length in the pellets. 20 mm or less is more preferable, 4 mm or more and 15 mm or less is further preferable, and 5 mm or more and 10 mm or less is particularly preferable.

The method for producing a liquid crystal polyester resin pellet of the present invention has the following aspects.
"11" The method for producing a liquid crystal polyester resin pellet according to any one of "1" to "10", which comprises a step of melt-kneading the liquid crystal polyester and the pitch-based carbon fiber.
"12" The step according to "11", which includes a step of cooling the melt-kneaded liquid crystal polyester resin composition to obtain a strand-shaped resin structure and a step of cutting the strand-shaped resin structure. A method for producing liquid crystal polyester resin pellets.
"13" With respect to 100 parts by mass of the liquid crystal polyester, the blending amount of the pitch-based carbon fiber is preferably 10 parts by mass to 100 parts by mass, more preferably 15 parts by mass to 100 parts by mass, and further preferably. Is 18 parts by mass to 100 parts by mass, more preferably 25 parts by mass to 100 parts by mass, further preferably 40 parts by mass to 100 parts by mass, and further preferably 60 parts by mass to 100 parts by mass. The method for producing a liquid crystal polyester resin pellet according to the above "11" or "12".

(Liquid crystal polyester resin molded product)
The liquid crystal polyester resin molded body of the present embodiment is a liquid crystal polyester resin molded body containing liquid crystal polyester and pitch-based carbon fibers, and has a shear rate of 1000 s ^-1 at a flow start temperature of the liquid crystal polyester of + 60 ° C. The melt viscosity of the pitch-based carbon fiber is less than 10 Pa · s, and the length-weighted average fiber length of the pitch-based carbon fiber is 100 μm or more. The flexural modulus of the liquid crystal polyester at a flow start temperature of + 60 ° C. at a shear rate of 1000 s ^-1 is less than 10 Pa · s, and the length-weighted average fiber length of the pitch-based carbon fibers is 100 μm or more. The rate is excellent. The molded product of the present embodiment can be produced by using the liquid crystal polyester resin pellets.
Here, the flow start temperature is a melt viscosity of 4800 Pa when the resin heated at a temperature rising rate of 4 ° C./min is extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under a load of 9.81 MPa. -The temperature indicating s.

The density of the pitch-based carbon fibers in the liquid crystal polyester resin molded product of the present embodiment is preferably 2.10 g / cm ³ or more, and more specifically, the density of the pitch-based carbon fibers in the liquid crystal polyester resin pellets. Is similar to. The density of the pitch-based carbon fibers in the liquid crystal polyester resin molded body obtained through the step of molding using the liquid crystal polyester resin pellets shall not change from the density of the pitch-based carbon fibers in the liquid crystal polyester resin pellets. be able to.

The length-weighted average fiber length of the pitch-based carbon fibers in the liquid crystal polyester resin molded body obtained through the step of molding using the liquid crystal polyester resin pellets is the length weighted of the pitch-based carbon fibers in the liquid crystal polyester resin pellets. When the average fiber length is 100 μm or more, it can be 100 μm or more, and the mechanical strength such as flexural modulus can be excellent.

The length-weighted average fiber length of the pitch-based carbon fibers in the molded product is preferably 100 μm or more and 500 μm or less, more preferably 100 μm or more and 300 μm or less, and more preferably 140 μm or more and 300 μm or less. When the pitch-based carbon fibers in the molded body are 100 μm or more, the bending strength and flexural modulus of the molded body are excellent. It is preferable that the pitch-based carbon fibers in the molded product are 500 μm or less because the appearance of the molded product is good.

The length-weighted average fiber length of the fibrous filler in the molded body can be obtained by the same method as the length-weighted average fiber length of the fibrous filler in the liquid crystal polyester resin pellets.

By going through the step of molding using the liquid crystal polyester resin pellets, a liquid crystal polyester resin molded body having an excellent flexural modulus can be obtained. The flexural modulus of the liquid crystal polyester resin molded product is preferably 20 GPa or more, more preferably 30 GPa or more, and further preferably 34 GPa or more. The flexural modulus of the liquid crystal polyester resin molded product can be measured in accordance with JIS K 7171 (Plastic-How to determine bending characteristics) and ISO178.

By going through the step of molding using the liquid crystal polyester resin pellets, a liquid crystal polyester resin molded body having an excellent flexural modulus can be obtained. The bending strength of the liquid crystal polyester resin molded product is preferably 165 MPa or more, more preferably 170 MPa or more, and further preferably 175 MPa or more. The bending strength of the liquid crystal polyester resin molded product can be measured in accordance with JIS K 7171 (Plastic-How to determine bending characteristics) and ISO178.

The liquid crystal polyester resin molded product of the present invention has the following aspects.
"21" A liquid crystal polyester resin molded product containing liquid crystal polyester and pitch-based carbon fibers.
The melt viscosity of the liquid crystal polyester at a shear rate of 1000s- ¹ at a flow start temperature of + 60 ° C. is less than 10 Pa · s.
A liquid crystal polyester resin molded product having a length-weighted average fiber length of 100 μm or more of the pitch-based carbon fibers.
Here, the flow start temperature is a melt viscosity of 4800 Pa when the resin heated at a temperature rising rate of 4 ° C./min is extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under a load of 9.81 MPa. -The temperature indicating s.
"22" The content ratio of the pitch-based carbon fiber is 10 parts by mass to 100 parts by mass, preferably 15 parts by mass to 100 parts by mass, and more preferably 18 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. It is 10 parts to 100 parts by mass, more preferably 25 parts by mass to 100 parts by mass, further preferably 40 parts by mass to 100 parts by mass, and further preferably 60 parts by mass to 100 parts by mass. The liquid crystal polyester resin molded body according to the above.

"23" The liquid crystal polyester contains a repeating unit represented by the following formulas (1), (2), (3) or (4).
The content of the repeating unit represented by the following formula (1) is 30 mol% or more and 100 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). It is preferably 30 mol% or more and 90 mol% or less, more preferably 40 mol% or more and 80 mol% or less, and further preferably 50 mol% or more and 70 mol% or less.
The content of the repeating unit represented by the following formula (2) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). It is preferably 6 mol% or more and 30 mol% or less, more preferably 7 mol% or more and 20 mol% or less, and further preferably 8 mol% or more and 17.5 mol% or less.
The content of the repeating unit represented by the following formula (3) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). It is preferably 3 mol% or more and 30 mol% or less, more preferably 4 mol% or more and 20 mol% or less, and further preferably 5 mol% or more and 12 mol% or less.
The content of the repeating unit represented by the following formula (4) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). The above, preferably 10 mol% or more and 35 mol% or less, more preferably 15 mol% or more and 30 mol% or less, still more preferably 17.5 mol% or more and 27.5 mol% or less. The liquid crystal polyester resin molded product according to "21" or "22". However, the total amount of the repeating units represented by the formulas (1), (2), (3) and (4) does not exceed 100 mol%.

"24" The content of the repeating unit represented by the formula (1) is 30 mol% or more and 90 mol with respect to the total amount of the repeating unit represented by the formulas (1), (2), (3) and (4). % Or less
When the content of the repeating unit represented by the formula (2) is 6 mol% or more and 30 mol% or less with respect to the total amount of the repeating units represented by the formulas (1), (2), (3) and (4). Yes,
When the content of the repeating unit represented by the formula (3) is 3 mol% or more and 30 mol% or less with respect to the total amount of the repeating units represented by the formulas (1), (2), (3) and (4). Yes,
When the content of the repeating unit represented by the formula (4) is 10 mol% or more and 35 mol% or less with respect to the total amount of the repeating units represented by the formulas (1), (2), (3) and (4). The liquid crystal polyester resin molded product according to the above "23". However, the total amount of the repeating units represented by the formulas (1), (2), (3) and (4) does not exceed 100 mol%.

"25" The melt viscosity of the liquid crystal polyester at a shear rate of 10000s- ¹ at a flow start temperature of + 60 ° C. is 1 Pa · s or more and less than 5 Pa · s, preferably 1 Pa · s or more and 4 Pa · s or less. The liquid crystal polyester resin molded product according to any one of "21" to "24".

"26" Density of the pitch-based carbon fiber is at 2.10 g / cm ³ or more 2.25 g / cm ³ or less, preferably 2.11 g / cm ³ or more 2.22 g / cm ³ or less, more preferably 2.12 g / cm ³ or more 2.20 g / cm ³ or less, much more preferably 2.13 g / cm ³ or more 2.20 g / cm ³ or less, any one of the "21" - "25" The liquid crystal polyester resin molded body according to.

"27" Of the above "21" to "26", the flow start temperature of the liquid crystal polyester is 280 ° C. or higher, preferably 280 ° C. or higher and 400 ° C. or lower, and more preferably 280 ° C. or higher and 380 ° C. or lower. The liquid crystal polyester resin molded product according to any one item.

"28" The length-weighted average fiber length of the pitch-based carbon fibers is 100 μm or more and 500 μm or less, preferably 100 μm or more and 300 μm or less, and more preferably 140 μm or more and 300 μm or less. The liquid crystal polyester resin molded product according to any one of the above.
"29" The melt viscosity of the liquid crystal polyester at a shear rate of 1000 s ^-1 at a flow start temperature of + 60 ° C. is 1 Pa · s or more and less than 10 Pa · s, preferably 1 Pa · s or more and 9 Pa · s or less, more preferably. The liquid crystal polyester resin composition according to any one of "21" to "28", wherein is 1 Pa · s or more and 8 Pa · s or less, and more preferably 5 Pa · s or more and 8 Pa · s or less.

"30" A liquid crystal polyester resin molded product containing a thermoplastic resin containing a liquid crystal polyester and a fibrous filler.
The content ratio of the liquid crystal polyester with respect to 100% by mass of the thermoplastic resin is 80% by mass or more and 100% by mass or less, preferably 85% by mass or more and 100% by mass or less, and more preferably 90% by mass or more and 100% by mass or less. The liquid crystal polyester resin molded body according to any one of the following "21] to "29".

(Manufacturing method of liquid crystal polyester resin molded product)
The method for producing a liquid crystal polyester resin molded product of the present embodiment includes a step of molding using the liquid crystal polyester resin pellets. The liquid crystal polyester resin pellet can be molded by a known molding method. As a method for producing the liquid crystal polyester resin molded product of the present embodiment, a melt molding method is preferable, and examples thereof include an injection molding method, an extrusion molding method such as a T-die method and an inflation method, a compression molding method, and a blow molding method. Vacuum forming method and press molding can be mentioned. Of these, the injection molding method is preferable.

For example, when the above-mentioned liquid crystal polyester resin pellet is used as a molding material and molded by an injection molding method, the liquid crystal polyester resin pellet is melted by using a known injection molding machine, and the melted liquid crystal polyester resin composition is placed in a mold. It is molded by injecting into.
Examples of known injection molding machines include TR450EH3 manufactured by Sodick Co., Ltd. and PS40E5ASE type hydraulic horizontal molding machine manufactured by Nissei Resin Industry Co., Ltd. Examples of the type of injection molding machine include an in-line type in which the pellet plasticizing part and the injection part are integrated, and a pre-plastic type injection molding machine in which the pellet plasticizing part and the injection part are independent. A pre-plastic injection molding machine is preferable because there is no check valve and the injection pressure can be reduced. Examples of the pre-plastic injection molding machine include TR450EH3 manufactured by Sodick Co., Ltd.

The cylinder temperature of the injection molding machine is appropriately determined according to the type of liquid crystal polyester, and is preferably set to a temperature 10 to 80 ° C. higher than the flow start temperature of the liquid crystal polyester used, for example, 300 to 400 ° C.

The temperature of the mold is preferably set in the range of room temperature (for example, 23 ° C.) to 180 ° C. from the viewpoint of the cooling rate and productivity of the liquid crystal polyester resin composition.

Since the molded product obtained by the manufacturing method of the present embodiment uses the liquid crystal polyester resin pellets of the present embodiment described above, the molded product has increased rigidity, is hard to bend, and is hard to respond to external stress. Can be manufactured.

The molded product obtained by the manufacturing method of the present embodiment described above can be generally applied to all applications to which the liquid crystal polyester resin can be applied, and is particularly suitable for applications in the automobile field.

Applications in the automobile field include, for example, injection molded products for automobile interior materials, injection molded products for ceiling materials, injection molded products for wheel house covers, injection molded products for trunk room lining, injection molded products for instrument panel skin materials, and handles. Injection molded product for cover, injection molded product for armrest, injection molded product for headrest, injection molded product for seat belt cover, injection molded product for shift lever boot, injection molded product for console box, injection molded product for horn pad, for knob Injection molding, injection molding for airbag cover, injection molding for various trims, injection molding for various pillars, injection molding for door lock bezel, injection molding for grab box, injection molding for defroster nozzle, for scuff plate Examples thereof include an injection molded product, an injection molded product for a steering wheel, and an injection molded product for a steering column cover.

Further, as applications in the automobile field, for example, as an injection molded body for an automobile exterior material, an injection molded body for a bumper, an injection molded body for a spoiler, an injection molded body for a mudguard, an injection molded body for a side molding, and an injection molded body for a radiator grill. Body, injection molding for wheel cover, injection molding for wheel cap, injection molding for cowl belt grill, injection molding for air outlet louver, injection molding for air scoop, injection molding for hood bulge, for fender Examples thereof include injection molded products and injection molded products for back doors.

Injection moldings for cylinders and head covers, injection moldings for engine mounts, injection moldings for air intake manifolds, injection moldings for throttle bodies, injection moldings for air intake pipes, radiator tanks as parts in the engine room for automobiles. Injection moldings for radiator support, injection moldings for water pumps and inlets, injection moldings for water pumps and outlets, injection moldings for thermostat housings, injection moldings for cooling fans, injection moldings for fan shrouds Body, injection molded body for oil pan, injection molded body for oil filter housing, injection molded body for oil filler cap, injection molded body for oil level gauge, injection molded body for timing belt, injection for timing belt cover Examples include molded parts and injection molded parts for engine covers.

Automotive fuel components include fuel caps, fuel filler tubes, automotive fuel tanks, fuel sender modules, fuel cutoff valves, quick connectors, canisters, fuel delivery pipes, fuel filler necks and the like.
Examples of automobile drive system components include shift lever housings and propeller shafts.
Examples of chassis parts for automobiles include stabilizers and linkage rods.

Other injection molded products for automobile parts include injection molded products for automobile head lamps, injection molded products for glass run channels, injection molded products for weather strips, injection molded products for drain hoses, and injection molded products for window washer tubes. Examples thereof include injection molded products for tubes, injection molded products for tubes, injection molded products for rack and pinion boots, and injection molded products for gaskets.
Above all, it can be preferably used for members that require rigidity.

In addition to the above, the molded body of the present embodiment includes a sensor, an LED lamp, a connector, a socket, a resistor, a relay case, a switch, a coil bobbin, a capacitor, a variable condenser case, an optical pickup, an oscillator, various terminal boards, and a metamorphic device. , Plugs, printed circuit boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, semiconductors, liquid crystal displays, FDD carriages, FDD chassis, motor brush holders, parabolic antennas, computer-related parts, microwave parts, It can also be applied to applications such as audio / audio equipment parts, lighting parts, air conditioner parts, office computer-related parts, telephone / FAX-related parts, and copying machine-related parts.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples shown below.

[Fluid start temperature of liquid crystal polyester]
First, using a flow tester (“CFT-500 type” manufactured by Shimadzu Corporation), about 2 g of liquid crystal polyester was filled into a cylinder equipped with a die having a nozzle having an inner diameter of 1 mm and a length of 10 mm. Next, under a load of 9.81 MPa (100 kg / cm ² ), while raising the temperature at a rate of 4 ° C./min, the liquid crystal polyester was melted and extruded from a nozzle, and the temperature showed a viscosity of 4800 Pa · s (48,000 poise). (Flow start temperature) was measured and used as the flow start temperature of the liquid crystal polyester.

<Manufacturing of liquid crystal polyester 1>
(1) Melt polymerization In a reactor equipped with a stirrer, torque meter, nitrogen gas introduction tube, thermometer and reflux condenser, 994.5 g (7.2 mol) of p-hydroxybenzoic acid, 4,4'-dihydroxy Add 446.9 g (2.4 mol) of biphenyl, 239.2 g (1.44 mol) of terephthalic acid, 159.5 g (0.96 mol) of isophthalic acid and 1347.6 g (13.2 mol) of anhydrous acetic acid, and 1 -0.2 g of methylimidazole was added and the inside of the reactor was sufficiently replaced with nitrogen gas.
Then, the temperature was raised from room temperature to 150 ° C. over 30 minutes under a nitrogen gas stream, and the temperature was maintained at 150 ° C. and refluxed for 1 hour.
Next, 0.9 g of 1-methylimidazole was added, and the temperature was raised from 150 ° C. to 320 ° C. over 2 hours and 50 minutes while distilling off by-product acetic acid and unreacted acetic anhydride, and when an increase in torque was observed. Was completed to obtain a prepolymer.

(2) Solid-phase polymerization The contents of the prepolymer thus obtained were taken out and cooled to room temperature. The obtained solid material was pulverized with a pulverizer to a particle size of about 0.1 to 1 mm to obtain a prepolymer powder. The prepolymer powder is heated in a nitrogen atmosphere from room temperature to 220 ° C. over 1 hour, heated from 220 ° C. to 240 ° C. over 0.5 hours, and held at 240 ° C. for 11 hours. Solid phase polymerization was performed. After solid-phase polymerization, it was cooled to obtain a powdery liquid crystal polyester 1.

The obtained liquid crystal polyester 1 contains 60 mol% of the repeating unit (1) in which Ar ¹ is a 1,4-phenylene group and Ar ² is a 1,3-phenylene group, based on the total amount of all the repeating units. A repeating unit (2) is 8.0 mol%, Ar ³ is a 1,4-phenylene group, a repeating unit (3) is 12 mol%, and Ar ⁴ is a 4,4'-biphenylene group. 4) has 20 mol%. The flow temperature of the liquid crystalline polyester 1 is 300 ° C., in the flow temperature + 60 ° C., a melt viscosity of 5 Pa · s at a shear rate of 1000 s ^-1, met melt viscosity of 2 Pa · s at a shear rate of 10000s ^-1 It was.

<Manufacturing of liquid crystal polyester 2>
(1) Melt polymerization In a reactor equipped with a stirrer, torque meter, nitrogen gas introduction tube, thermometer and reflux condenser, 994.5 g (7.2 mol) of p-hydroxybenzoic acid, 4,4'-dihydroxy Biphenyl 446.9 g (2.4 mol), terephthalic acid 299.0 g (1.8 mol), isophthalic acid 99.7 g (0.6 mol), and anhydrous acetic acid 1347.6 g (13.2 mol) were charged. 0.2 g of 1-methylimidazole was added, and the inside of the reactor was sufficiently replaced with nitrogen gas. Then, the temperature was raised from room temperature to 150 ° C. over 30 minutes under a nitrogen gas stream, and the temperature was maintained at 150 ° C. and refluxed for 1 hour.

Next, 0.9 g of 1-methylimidazole was added, and the temperature was raised from 150 ° C. to 320 ° C. over 3 hours while distilling off by-product acetic acid and unreacted acetic anhydride, and the reaction was performed at the time when an increase in torque was observed. At the end, the contents were taken out and cooled to room temperature. The obtained solid material was pulverized with a pulverizer to a particle size of about 0.1 to 1 mm to obtain a prepolymer powder.

(2) Solid-Phase Polymerization The powder of this prepolymer is heated from room temperature to 250 ° C. over 1 hour in a nitrogen atmosphere, heated from 250 ° C. to 285 ° C. over 5 hours, and held at 285 ° C. for 3 hours. By doing so, solid-phase polymerization was carried out. After solid-phase polymerization, it was cooled to obtain a powdery liquid crystal polyester 2. The liquid crystal polyester 2 contains 60 mol% of the repeating unit (1) in which Ar ¹ is a 1,4-phenylene group and Ar ² is a repeating unit having a 1,3-phenylene group, based on the total amount of all the repeating units. (2) is 5.0 mol%, Ar ³ is a repeating unit (3) having a 1,4-phenylene group is 15 mol%, and Ar ⁴ is a repeating unit (4) having a 4,4'-biphenylene group. Has 20 mol%. Flow temperature of the liquid crystal polyester 2 is 320 ° C., in the flow temperature + 60 ° C., a melt viscosity of 15 Pa · s at a shear rate of 1000 s ^-1, met melt viscosity of 5 Pa · s at a shear rate of 10000s ^-1 It was.

<Manufacturing of liquid crystal polyester 3>
(1) Melt polymerization A reactor equipped with a stirrer, a torque meter, a nitrogen gas introduction tube, a thermometer and a reflux condenser, 6-hydroxy-2-naphthoic acid 1034.99 g (5.5 mol), 2,6 -Naphthalene dicarboxylic acid 378.33 g (1.75 mol), terephthalic acid 83.07 g (0.5 mol), hydroquinone 272.52 g (2.475 mol, 2,6-naphthalene dicarboxylic acid and terephthalic acid total amount On the other hand, 0.225 mol excess), 1226.87 g (12 mol) of anhydrous acetic acid, and 0.17 g of 1-methylimidazole as a catalyst were added, and the gas in the reactor was replaced with nitrogen gas, and then under a nitrogen gas stream, The temperature was raised from room temperature to 145 ° C. over 15 minutes with stirring, and the mixture was refluxed at 145 ° C. for 1 hour.

Then, while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 145 ° C. to 310 ° C. over 3.5 hours, held at 310 ° C. for 3 hours, and then the contents were taken out and brought to room temperature. Cooled down to. The obtained solid material was pulverized with a pulverizer to a particle size of about 0.1 to 1 mm to obtain a prepolymer powder.

(2) Solid-phase polymerization The powder of this prepolymer is heated from room temperature to 250 ° C. over 1 hour in a nitrogen atmosphere, heated from 250 ° C. to 295 ° C. over 8 hours, and held at 295 ° C. for 8 hours. By doing so, solid-phase polymerization was carried out. After solid-phase polymerization, it was cooled to obtain a powdery liquid crystal polyester 3. The liquid crystal polyester 3 contains 55 mol% of the repeating unit (1) in which Ar ¹ is a 2,6-naphthylene group and Ar ² is a repeating unit having a 2,6-naphthylene group, based on the total amount of all repeating units. (2) is 17.5 mol%, Ar ³ is a repeating unit (3) having a 1,4-phenylene group of 5 mol%, and Ar ⁴ is a repeating unit (4) having a 1,4-phenylene group. Has 5.5 mol%. The flow temperature of the liquid crystalline polyester 3 is 310 ° C., in the flow temperature + 60 ° C., a melt viscosity of 8 Pa · s at a shear rate of 1000 s ^-1, met melt viscosity of 4 Pa · s at a shear rate of 10000s ^-1 It was.

<Measurement method of length-weighted average fiber length>
The length-weighted average fiber length of the pitch-based carbon fibers in the resin pellets and the injection-molded test piece (that is, the molded product) was measured by the following measuring method.
(1) First, as a test sample, a width 10 mm × length 20 mm × thickness 4 mm is cut out from the central portion of a multipurpose test piece (type A1) conforming to JIS K 7139. Also, select about 5 g of resin pellets. These test samples are sintered in a muffle furnace to remove the resin component. However, the firing conditions are 500 ° C. and 3 hours.
(2) A pitch-based carbon fiber dispersion is prepared by dispersing only pitch-based carbon fibers in 500 mL of an aqueous solution containing 0.05% by volume of a surfactant (NICRO90 manufactured by INTERRNATIONAL PRODUCTS CORPORATION).
(3) Take out 50 mL from the 500 mL dispersion, filter under reduced pressure using a filter paper for Kiriyama funnel (No. 5C) with a diameter of 90 mm, and use a microscope (manufactured by Keyence Co., Ltd., VH) to filter the pitch-based carbon fibers dispersed in the filter paper. -ZST) is observed, and 5 images at a magnification of 100 times (in the case of a resin pellet sample and a molded product sample) are taken for each sample.
(4) All of the five captured images are binarized with image processing software (WinROOF2018 manufactured by Mitani Corporation), and the fiber length is measured.

(How to measure fiber length)
(a) Perform monochrome pixel conversion processing on the captured image.
(b) Perform a binarization process so that only the photographed fibers are colored.
(c) Measure the fiber length using the needle-shaped separation function of the image processing software.
(d) Measure the fiber lengths of fibers that could not be binarized in (c) or curved fibers by multipoint measurement.
However, in (c) and (d), fibers having a diameter of 10 μm or less are judged to be noise and should not be included in the measured number of fibers n. If n> 500 and the number of fibers to be measured n does not exceed 500, the process returns to (3), additional images are taken, and measurement is performed until n exceeds 500.

(5) From the fiber lengths of the pitch-based carbon fibers of the five images, the length-weighted average fiber length lm = (Σli ² × ni) / (Σli × ni) is obtained (Σni> 500).
li: Fiber length of pitch-based carbon fibers ni: Number of pitch-based carbon fibers with fiber length li

<Measurement method of melt viscosity of liquid crystal polyester>
A capillary rheometer (“Capillary Graph 1D” manufactured by Toyo Seiki Co., Ltd.) equipped with a capillary of 0.5 mmΦ × 10 mm was used for measuring the melt viscosity of the liquid crystal polyester which is a raw material of the resin pellets. The liquid crystal polyester 20g drying for 3 hours at 120 ° C. was placed in the capillary was set to a temperature of flow temperature + 60 ° C., the melt viscosity was measured at a shear rate of 1000 s ^-1, and 10000s ^-1.

The melt viscosity of the liquid crystal polyester in the resin pellets can be separated as follows, and the melt viscosity can be measured.
By using a single-screw extruder or a twin-screw extruder, resin pellets are melted in a cylinder at a temperature of 360 ° C. and extruded at a high pressure of 10 MPa or more through a mesh with an outlet of 10 μm to 50 μm or a die with a hole diameter of 50 μm. The liquid crystal polyertel and the fibrous filler of the pitch-based carbon fiber are separated. Using the obtained liquid crystal polyester, the melt viscosity was measured in the same manner as the method for measuring the melt viscosity of the liquid crystal polyester used as a raw material for the resin pellets described above.

<Manufacturing of liquid crystal polyester resin pellets>
(Example 1)
Liquid polyester 1 and pitch-based carbon fiber (Dialead (registered trademark) K223HE manufactured by Mitsubishi Chemical Co., Ltd., cut length 6 mm, tensile strength 3800 MPa, tensile elastic modulus 900 GPa, density 2. A twin-screw extruder (PCM30-HS manufactured by Ikekai Iron Works Co., Ltd.) that has a main raw material feeder in the upstream part and a side feeder in the downstream part at a ratio of 100 parts by mass to 82 parts by mass of 20 g / cm ³ ). , Cylinder temperature: 360 ° C., screw rotation speed 100 rpm), liquid polyester is supplied from the main raw material feeder, melt-kneaded, pitch-based carbon fibers are supplied from the side feeder, melt-kneaded, and then the liquid crystal polyester resin composition. The liquid crystal polyester resin pellet of Example 1 having a columnar shape (length 3 mm) made of the above was prepared. The length-weighted average fiber length of the pitch-based carbon fibers contained in the pellet was 210 μm. The flow start temperature of the liquid crystal polyester 1 separated from the obtained pellets is 300 ° C., the melt viscosity at a shear rate of 1000 s ^-1 at the flow start temperature of + 60 ° C. is 5 Pa · s, and the melt viscosity at a shear rate of 10000 s ^-1. Was 2 Pa · s.

(Examples 2 to 3)
Example 2 is the same as in Example 1 except that the blending ratio of 100 parts by mass to 82 parts by mass of the liquid crystal polyester 1 to pitch carbon fiber in Example 1 is changed to the blending ratio shown in Table 1. To 3 liquid crystal polyester resin pellets were obtained. The length-weighted average fiber lengths of the pitch-based carbon fibers in the pellets were 280 μm (Example 2) and 155 μm (Example 3). The liquid crystal polyester 1 separated from Examples 2 and 3 has a flow start temperature of 300 ° C., a melt viscosity of 5 Pa · s at a shear rate of 1000 s ^-1 and a shear rate of 10000 s ^-1 at a flow start temperature of + 60 ° C. The melt viscosity of was 2 Pa · s.

(Example 4)
The liquid crystal polyester 1 obtained in the <manufacturing of the liquid crystal polyester 1> in Example 1 was changed to the liquid crystal polyester 3 obtained in the <manufacturing of the liquid crystal polyester 3>, and the cylinder temperature was changed from 360 ° C. to 370 ° C. Liquid crystal polyester resin pellets of Example 4 were obtained in the same manner as in Example 1 except that they were changed. The length-weighted average fiber length of the pitch-based carbon fibers in the pellet was 212 μm. The flow start temperature of the liquid crystal polyester 3 separated from the obtained pellets is 310 ° C., the melt viscosity at a shear rate of 1000 s ^-1 at the flow start temperature + 60 ° C. is 8 Pa · s, and the melt viscosity at a shear rate of 10000 s ^-1. Was 4 Pa · s.

(Comparative Example 1)
The liquid crystal polyester 1 obtained in the <manufacturing of the liquid crystal polyester 1> in Example 1 was changed to the liquid crystal polyester 2 obtained in the above <manufacturing of the liquid crystal polyester 2>, and the liquid crystal polyester 1 pair pitch carbon fiber was obtained. Except for changing the blending ratio of 100 parts by mass to 82 parts by mass to the blending ratio of 100 parts by mass to 100 parts by mass of liquid crystal polyester 2 and pitch-based carbon fiber, and changing the cylinder temperature 360 ° C to 380 ° C. The liquid crystal polyester resin pellet of Comparative Example 1 was obtained in the same manner as in Example 1. The length-weighted average fiber length of the pitch-based carbon fibers in the pellet was 182 μm. The flow start temperature of the liquid crystal polyester 2 separated from the obtained pellets is 320 ° C., the melt viscosity at a shear rate of 1000 s ^-1 at the flow start temperature of + 60 ° C. is 15 Pa · s, and the melt viscosity at a shear rate of 10000 s ^-1. Was 5 Pa · s.

(Comparative Example 2)
The liquid crystal polyester 1 obtained in the <manufacturing of the liquid crystal polyester 1> in Example 1 was changed to the liquid crystal polyester 2 obtained in the above <manufacturing of the liquid crystal polyester 2>, and the liquid crystal polyester 1 pair pitch carbon fiber was obtained. Comparative Example 2 in the same manner as in Example 1 except that the blending ratio of 100 parts by mass to 82 parts by mass was changed to the blending ratio of 2 parts by mass of liquid crystal polyester to 82 parts by mass of pitch-based carbon fiber. Liquid polyester resin pellets were obtained. The length-weighted average fiber length of the pitch-based carbon fibers in the pellet was 260 μm. The flow start temperature of the liquid crystal polyester separated from the obtained pellets is 320 ° C., and the melt viscosity at a shear rate of 1000 s ^-1 and the melt viscosity at a shear rate of 10000 s ^-1 at a flow start temperature of + 60 ° C. It was 5 Pa · s.

(Comparative Example 3)
The liquid crystal polyester 1 obtained in the <manufacturing of the liquid crystal polyester 1> in Example 1 was changed to the liquid crystal polyester 2 obtained in the above <manufacturing of the liquid crystal polyester 2>, and the liquid crystal polyester 1 pair pitch carbon fiber was obtained. The liquid crystal of Comparative Example 3 was obtained in the same manner as in Example 1 except that the mixing ratio of 100 parts by mass to 82 parts by mass was changed to the mixing ratio of 2 parts by mass of liquid crystal polyester to 18 parts by mass of pitch-based carbon fiber. Polyester resin pellets were obtained. The length-weighted average fiber length of the pitch-based carbon fibers in the pellet was 323 μm. The flow start temperature of the liquid crystal polyester separated from the obtained pellets is 320 ° C., and the melt viscosity at a shear rate of 1000 s ^-1 and the melt viscosity at a shear rate of 10000 s ^-1 at a flow start temperature of + 60 ° C. It was 5 Pa · s.

(Comparative Example 4)
The liquid crystal polyester 1 and the pitch-based carbon fiber 1 are blended with a tumbler at a blending amount of 100 parts by mass to 82 parts by mass, and are collectively charged from the main raw material feeder of the twin-screw extruder described in Example 1. The liquid crystal polyester resin pellet of Comparative Example 4 having a cylindrical shape (length 3 mm) made of a liquid crystal polyester resin composition was produced by melt-kneading under the conditions of a cylinder temperature of 310 ° C. and a screw rotation speed of 200 rpm.
The length-weighted average fiber length of the pitch-based carbon fibers in the pellet was 95 μm. The flow start temperature of the liquid crystal polyester 1 separated from the obtained pellets is 300 ° C., the melt viscosity at a shear rate of 1000 s ^-1 at the flow start temperature of + 60 ° C. is 5 Pa · s, and the melt viscosity at a shear rate of 10000 s ^-1. Was 2 Pa · s.

(Comparative Example 5)
Liquid crystal polyester resin pellets were produced in the same manner as in Comparative Example 4 except that the ratio of the blending amounts of the liquid crystal polyester 1 and the pitch-based carbon fiber 1 in Comparative Example 4 was changed to 100 parts by mass to 18 parts by mass. The length-weighted average fiber length of the pitch-based carbon fibers in the pellet was 99 μm. The flow start temperature of the liquid crystal polyester separated from the obtained pellets is 300 ° C., and the melt viscosity at a shear rate of 1000 s ^-1 and the melt viscosity at a shear rate of 10000 s ^-1 at a flow start temperature of + 60 ° C. It was 2 Pa · s.

(Comparative Example 6)
The liquid crystal polyester 1 obtained in the above <Production of liquid crystal polyester 1> in Example 1 was changed to a PPS resin (manufactured by Toray Industries, Inc., polyphenylene sulfide resin, grade: A900, melting point 280 ° C.), and the melting temperature was changed. The resin pellets of Comparative Example 6 were obtained in the same manner as in Example 1 except that the temperature was changed to 340 ° C. The length-weighted average fiber length of the pitch-based carbon fibers 1 in the pellet was 182 μm.

<Manufacturing of injection molded test pieces>
The liquid crystal polyester resin pellets of Examples 1 to 3 were put into an injection molding machine TR450EH3 (manufactured by Sodick Co., Ltd.) having a cylinder temperature of 360 ° C., and into a mold having a mold temperature of 100 ° C., an injection speed of 20 mm / s and screw rotation. A multipurpose test piece (type A1) conforming to JIS K 7139 was produced by injecting at several 100 rpm, a holding pressure of 100 MPa, and a back pressure of 0 MPa.

The liquid crystal polyester resin pellet of Example 4 is put into an injection molding machine TR450EH3 (manufactured by Sodick Co., Ltd.) having a cylinder temperature of 370 ° C., and the injection speed is 20 mm / s and the screw rotation speed is 100 rpm into a mold having a mold temperature of 100 ° C. A multipurpose test piece (type A1) conforming to JIS K 7139 was produced by injecting at a holding pressure of 100 MPa and a back pressure of 0 MPa.

The liquid crystal polyester resin pellets of Comparative Examples 1 to 3 were put into an injection molding machine TR450EH3 (manufactured by Sodick Co., Ltd.) having a cylinder temperature of 380 ° C., and into a mold having a mold temperature of 100 ° C., an injection speed of 20 mm / s and screw rotation. A multipurpose test piece (type A1) conforming to JIS K 7139 was produced by injecting at several 100 rpm, a holding pressure of 100 MPa, and a back pressure of 0 MPa.

The liquid crystal polyester resin pellets of Comparative Examples 4 to 5 were put into an injection molding machine TR450EH3 (manufactured by Sodick Co., Ltd.) having a cylinder temperature of 360 ° C., and the injection speed was 20 mm / s and the screw was rotated into a mold having a mold temperature of 100 ° C. A multipurpose test piece (type A1) conforming to JIS K 7139 was produced by injecting at several 100 rpm, a holding pressure of 100 MPa, and a back pressure of 0 MPa.

The PPS resin pellet of Comparative Example 6 was put into an injection molding machine TR450EH3 (manufactured by Sodick Co., Ltd.) having a cylinder temperature of 340 ° C., and into a mold having a mold temperature of 100 ° C., an injection speed of 20 mm / s and a screw rotation speed of 100 rpm. A multipurpose test piece (type A1) conforming to JIS K 7139 was produced by injecting at a holding pressure of 100 MPa and a back pressure of 0 MPa.

<Bending test>
From the multipurpose test piece (type A1) conforming to JIS K 7171 (Plastic-How to determine bending characteristics) and ISO178, and JIS K 7139 of each example obtained, width 10 mm x thickness 4 mm x length 80 mm. A test piece was cut out.
This test piece was subjected to a 3-point bending test 5 times using a Tencilon universal material tester RTG-1250 (manufactured by A & D Co., Ltd.) at a test speed of 2 mm / min, a distance between fulcrums of 64 mm, and an indenter radius of 5 mm. The bending strength and the flexural modulus were obtained from the average value. The measurement results are shown in Tables 1 to 3.

From the results shown in Tables 1 to 3, the content ratio of the pitch-based carbon fibers in the liquid crystal polyester resin pellets of Examples 1 to 4 is 82 parts by mass to 100 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. The injection-molded test piece (that is, the molded product) produced by using the liquid crystal polyester resin pellets of Examples 1 and 3 to 4 is an injection-molded test piece (that is, a molded product) produced by using the resin pellets of Comparative Examples 1 to 6. It was confirmed that the bending elasticity was higher than that of the molded product.

The same applies to an injection molded test piece (that is, a molded product) produced by using the liquid crystal polyester resin pellets of Example 2 in which the content ratio of the pitch-based carbon fibers is 18 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. , The content ratio of the pitch-based carbon fiber is 18 parts by mass with respect to 100 parts by mass of the liquid crystal polyester, as compared with the injection molding test piece (that is, the molded product) produced by using the resin pellets of Comparative Examples 3 and 5. It was confirmed that the bending elasticity was remarkably high.

Claims

Liquid crystal polyester resin pellets containing liquid crystal polyester and pitch-based carbon fibers.
The melt viscosity of the liquid crystal polyester at a shear rate of 1000s- 1 at a flow start temperature of + 60 ° C. is less than 10 Pa · s.
A liquid crystal polyester resin pellet having a length-weighted average fiber length of 100 μm or more of the pitch-based carbon fibers.
Here, the flow start temperature is a melt viscosity of 4800 Pa when the resin heated at a temperature rising rate of 4 ° C./min is extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under a load of 9.81 MPa. -The temperature indicating s.
The liquid crystal polyester resin pellet according to claim 1, wherein the content ratio of the pitch-based carbon fibers is 10 parts by mass to 100 parts by mass with respect to 100 parts by mass of the liquid crystal polyester.
The liquid crystal polyester contains a repeating unit represented by the following formula (1), (2), (3) or (4).
The content of the repeating unit represented by the following formula (1) is 30 mol% or more and 100 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). Is below
The content of the repeating unit represented by the following formula (2) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). Is below
The content of the repeating unit represented by the following formula (3) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). Is below
The content of the repeating unit represented by the following formula (4) is 0 mol% or more and 35 mol% with respect to the total amount of the repeating units represented by the following formulas (1), (2), (3) and (4). The liquid crystal polyester resin pellet according to claim 1 or 2, which is as follows.
(1) -O-Ar 1- CO-
(2) -CO-Ar 2- CO-
(3) -CO-Ar 3- CO-
(4) -O-Ar 4- O-
(In formulas (1) to (4), Ar 1 represents a 1,4-phenylene group or a 2,6-naphthylene group. Ar 2 represents a 1,3-phenylene group or a 2,6-naphthylene group. Ar 3 represents a phenylene group (excluding 1,3-phenylene group), a naphthylene group (excluding 2,6-naphthylene group), or a biphenylene group. Ar 4 represents a phenylene group. , Naphthalene group, or biphenylene group.)
The liquid crystal polyester resin pellet according to any one of claims 1 to 3, wherein the melt viscosity of the liquid crystal polyester at a shear rate of 10000 s -1 at a flow start temperature of + 60 ° C. is less than 5 Pa · s.
The liquid crystal polyester resin pellet according to any one of claims 1 to 4, wherein the density of the pitch-based carbon fibers is 2.10 g / cm 3 or more.
The method for producing a liquid crystal polyester resin pellet according to any one of claims 1 to 5, which comprises a step of melt-kneading the liquid crystal polyester and the pitch-based carbon fiber.
A liquid crystal polyester resin molded product containing liquid crystal polyester and pitch-based carbon fibers.
The melt viscosity of the liquid crystal polyester at a shear rate of 1000s- 1 at a flow start temperature of + 60 ° C. is less than 10 Pa · s.
A liquid crystal polyester resin molded product having a length-weighted average fiber length of 100 μm or more of the pitch-based carbon fibers.
Here, the flow start temperature is a melt viscosity of 4800 Pa when the resin heated at a temperature rising rate of 4 ° C./min is extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm under a load of 9.81 MPa. -The temperature indicating s.