JP2020164738A - Liquid crystal polyester molded body and connector - Google Patents

Abstract

A liquid crystal polyester molded article in which the bending strength of an ultra-thin portion of a member constituting a product is further enhanced, and a connector using the same are provided. A liquid crystal polyester molded body, wherein the crystallite size at the center of the molded body calculated from the crystallite size obtained by [Method for measuring crystallite size] is 120×10 −10 m or more. Polyester molding. [Method for measuring crystallite size] The crystallite size of the liquid crystalline polyester molded product is determined by the diffraction peak of the 110 plane in the X-ray diffraction spectrum measured by the wide-angle X-ray diffraction method using X-rays with a wavelength of 1 × 10 -10 m. based on the Scherrer formula represented by formula (1). where D is the crystallite size, λ is the measured X-ray wavelength, β is the half-width in radians, θ is the diffraction angle, and K is the Scherrer constant (0.94). D=K・λ/βcosθ (1) [Selection diagram] None

Description

The present invention relates to a liquid crystal polyester molded product and a connector.

Liquid crystal polyester is used as an injection molding material for manufacturing electrical and electronic parts because it has excellent melt fluidity, heat resistance, strength, and rigidity. Taking advantage of these characteristics, liquid crystal polyester has been adopted for electrical / electronic parts, mechanical parts, etc., and its applications are expanding. Above all, it is suitably used for electric / electronic parts such as connectors, relays, and bobbins that require high fluidity.

On the other hand, since the molecular chain of the liquid crystal polyester is easily oriented in the flow direction during molding, there is a problem that the molded body is likely to shrink or expand, or anisotropy of mechanical properties is likely to occur.
To solve such a problem, a liquid crystal resin composition in which two kinds of liquid crystal polyesters having different crystal structures and the like are mixed has been proposed (see Patent Document 1). By using this liquid crystal resin composition, the anisotropy of the molded product and the weld strength can be improved.

JP-A-2010-174114

By the way, in recent years, the miniaturization and lightening of electrical and electronic products have been progressing more and more, and the electrical and electronic parts such as connectors used for them are required to further improve the mechanical properties such as bending strength.
However, in the molded product using the conventional liquid crystal resin composition as described above, the strength of the members constituting the product, particularly the thin ultra-thin portion (here, the product thickness of 0.10 mm or less). ) There is a requirement for bending strength.

The present invention has been made in view of the above circumstances, and provides a liquid crystal polyester molded body in which the bending strength of an ultra-thin portion of a member constituting a product is further enhanced, and a connector using the same. The purpose is.

As a result of diligent studies, the present inventors have adopted a method for obtaining information on a local region in the thickness direction with high resolution in a liquid crystal polyester molded product, that is, an X-ray scattering method using a large-scale radiation facility. By doing so, it was newly found that the crystallite size at the center of the molded body and the bending strength of the molded body are strongly correlated, and the present invention has been completed.
In order to solve the above problems, the present invention adopts the following configuration.

One aspect of the present invention is a liquid crystal polyester molded body, and the crystallite size at the center of the molded body calculated from the crystallite size obtained by the following [method for measuring crystallite size] is 120 × 10 ⁻¹⁰ m. It is a liquid crystal polyester molded body characterized by the above.
[Measurement method of crystallite size]
The crystallite size of the liquid crystal polyester molded product is determined by the following equation (1) based on the diffraction peak of 110 planes in the X-ray diffraction spectrum measured by the wide-angle X-ray diffraction method using X-rays having a wavelength of 1 × 10 ⁻¹⁰ m. ) Is obtained from the Scherrer equation.
D = K · λ / βcosθ ・ ・ ・ (1)
In the equation, D is the crystallite size, λ is the measured X-ray wavelength, β is the full width at half maximum (radian), θ is the diffraction angle, and K is the Scherrer constant (0.94).

In the liquid crystal polyester molded product according to one aspect of the present invention, the average crystallite size of the entire molded product calculated from the crystallite size obtained by the above [method for measuring crystallite size] is 100 × 10 ⁻¹⁰ m or more. It may be.

In the liquid crystal polyester molded product of one aspect of the present invention, the liquid crystal polyester has a repeating unit (u1) represented by the following formula (2), a repeating unit (u2) represented by the following formula (3), and the like. It has a repeating unit (u3) represented by the following formula (4), and the ratio of the repeating unit containing a 2,6-naphthylene group among the repeating units (u1) to (u3) is the liquid crystal polyester. It may be 40 mol% or more with respect to the ratio of the total of all the repeating units constituting.
-O-Ar ^1- CO- (2)
-CO-Ar ^2- CO- ... (3)
-X-Ar ^3- Y- (4)
In the formula, Ar ¹ , Ar ² and Ar ³ independently represent a phenylene group, a naphthylene group or a biphenylylene group, respectively. However, the hydrogen atom contained in these phenylene group, naphthylene group or biphenylylene group may be substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. X and Y each independently represent an oxygen atom or an imino group (-NH-).

In the liquid crystal polyester molded product according to one aspect of the present invention, the liquid crystal polyester molded product having at least one side length of 0.1 mmt or less, which is 5 mm × 10 mm × 0.1 mmt, is 0. In the direction of 1 mmt, the crystallite size at the center of the molded product calculated from the crystallite size obtained by the above [method for measuring crystallite size] is 120 × 10 ^-10 m or more and 180 × 10 ^-10 m or less. May be.

Further, one aspect of the present invention is a connector characterized by being made of the liquid crystal polyester molded product.

According to one aspect of the present invention, it is possible to provide a liquid crystal polyester molded product in which the bending strength of an ultra-thin portion of a member constituting a product is further enhanced, and a connector using the same.

It is a perspective view which shows the mold (the mold for measuring the thin-walled flow length) used when manufacturing the liquid crystal polyester molded body. It is a figure which shows the relationship between the distance from the outermost surface of each liquid crystal polyester molded article of Test Example 3, Test Example 5 and Test Example 6 and the crystallite size. It is a figure which shows the relationship between the distance from the outermost surface of each liquid crystal polyester molded article of Test Example 3 and Test Example 4, and the crystallite size. It is a figure which shows the relationship between the distance from the outermost surface of each liquid crystal polyester molded article of Test Example 1 and Test Example 5, and the crystallite size.

(Liquid crystal polyester molded product)
In the liquid crystal polyester molded product of the present embodiment, the crystallite size at the center of the molded product calculated from the crystallite size obtained by the [method for measuring crystallite size] described later is 120 × 10 ⁻¹⁰ m or more.

Regarding the liquid crystal polyester molded product of the present embodiment, the crystallite size at the center of the molded product is 120 × 10 ^-10 m or more, preferably 130 × 10 ^-10 m or more, and more preferably 140 × 10 ^-10 m or more. ..
The crystallite size at the center of the molded product is preferably 220 × 10 ^-10 m or less, more preferably 200 × 10 ^-10 m or less, and further preferably 180 × 10 ^-10 m or less as an upper limit value. It is particularly preferably 160 × 10 ^-10 m or less. The lower limit value and the upper limit value of the crystallite size at the center of the molded product can be arbitrarily combined.
When the crystallite size at the center of the molded product is equal to or greater than the lower limit of the above range, a liquid crystal polyester molded product having a higher bending strength at the ultra-thin portion of the member can be obtained. On the other hand, when the crystallite size at the center of the molded product is not more than the upper limit of the above-mentioned preferable range, it becomes easy to obtain a liquid crystal polyester molded product having higher impact strength.

For the liquid crystal polyester molded product of the present embodiment, the average crystallite size of the entire molded product calculated from the crystallite size obtained by the above [method for measuring crystallite size] is 100 × 10 ⁻¹⁰ m or more. It is preferable, 110 × 10 ^-10 m or more is more preferable, and 120 × 10 ^-10 m or more is further preferable.
Further, the average crystallite size of the entire molded product is preferably 220 × 10 ^-10 m or less, more preferably 200 × 10 ^-10 m or less, and further preferably 180 × 10 ^-10 m or less as an upper limit value. It is particularly preferably 160 × 10 ^-10 m or less. The lower limit value and the upper limit value of the average crystallite size of the entire molded product can be arbitrarily combined.
When the average crystallite size of the entire molded product is at least the lower limit of the above-mentioned preferable range, it becomes easy to obtain a liquid crystal polyester molded product in which the bending strength of the ultra-thin portion of the member is further increased. On the other hand, when the average crystallite size of the entire molded product is not more than the upper limit of the above-mentioned preferable range, it becomes easy to obtain a liquid crystal polyester molded product having higher impact strength.

[Measurement method of crystallite size]
The crystallite size of the liquid crystal polyester molded product is determined by the following equation (1) based on the diffraction peak of 110 planes in the X-ray diffraction spectrum measured by the wide-angle X-ray diffraction method using X-rays having a wavelength of 1 × 10 ⁻¹⁰ m. ) Is obtained from the Scherrer equation.
D = K · λ / βcosθ ・ ・ ・ (1)
In the equation, D is the crystallite size, λ is the measured X-ray wavelength, β is the full width at half maximum (radian), θ is the diffraction angle, and K is the Scherrer constant (0.94).

It should be noted that determining the crystallite size by the above equation (1) is a conventionally used method (for example, "X-ray structure analysis-determining the arrangement of atoms-", April 30, 2002, 3rd edition. Published by Yoshio Waseda and Eiichiro Matsubara, see).

In the present embodiment, the following procedure (1) is performed using a wide-angle X-ray diffraction method, preferably an X-ray scattering method using a beamline (beam size of about 1 μm) of a large-scale radiation facility (SPring-8). The crystallite size is obtained by performing ~ (5).

Procedure (1): First, X-ray diffraction measurement is performed by continuously irradiating the sample molded body with X-rays having a wavelength of 1 × 10 ^-10 m at intervals of 2 μm in the thickness direction of the molded body. .. The start point and end point, which are the ends where X-rays are incident on the molded body, are defined as the point where the diffraction peak of 110 planes derived from the liquid crystal polyester appears (start point) and the point where it disappears (end point), respectively. The central part of the molded body is defined as the position of the midpoint between the start point and the end point.

Step (2): Determine the diffraction peak of 110 planes derived from liquid crystal polyester.
Procedure (3): The full width at half maximum (β) of the determined diffraction peak of the 110 plane is obtained.
Step (4): Determine the crystallite size using Scherrer's equation.
Procedure (5): The crystallite size is calculated by the procedure (3) and the procedure (4) for all the measurement data from the start point to the end point when the X-ray is incident on the molded product.

The "crystallite size at the center of the molded product" in the liquid crystal polyester is the value of the crystallite size at the center in the thickness direction of the molded product obtained by the above procedure.
The "average crystallite size of the entire molded product" in the liquid crystal polyester is the average value of the crystallite size of the entire molded product in the thickness direction obtained by the above procedure.
In the above [method for measuring crystallite size], the shape of the molded product may be arbitrary, and the position for irradiating X-rays may be appropriately selected in the direction in which the thickness of the molded product is the thinnest.

In the liquid crystal polyester molded body of the present embodiment, for example, the crystallite size at the center of the molded body and the average crystallite size of the entire molded body are controlled by selecting the type of liquid crystal polyester and the manufacturing method of the molded body. Can be done.
As for the control by the type of the liquid crystal polyester, the type of the repeating unit constituting the liquid crystal polyester or the ratio thereof may be appropriately selected.

<Liquid crystal polyester>
The liquid crystal polyester used in the molded product of the present embodiment is a polyester that exhibits liquid crystallinity in a molten state, and is preferably one that melts at a temperature of 450 ° C. or lower.
The liquid crystal polyester 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. As the liquid crystal polyester in the present embodiment, a fully aromatic liquid crystal polyester in which only an aromatic compound is polymerized as a raw material monomer is preferable.

The liquid crystal polyester used in the molded product of the present embodiment is, for example, at least one selected from the group consisting of aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, aromatic hydroxyamine and aromatic diamine. Polymer obtained by polycondensing (polycondensing) the compound of the above; polymer obtained by polymerizing a plurality of kinds of aromatic hydroxycarboxylic acids; aromatic dicarboxylic acid and aromatic diol, aromatic hydroxyamine and aromatic diamine. A polymer obtained by polymerizing at least one compound selected from the group consisting of; a polymer obtained by polymerizing a polyester such as polyethylene terephthalate and an aromatic hydroxycarboxylic acid.

Among them, aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, and at least one compound selected from the group consisting of aromatic diols, aromatic hydroxyamines and aromatic diamines are polycondensed. Polymers are preferred.

Here, aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic hydroxyamines and aromatic diamines are polymerizable ester-forming derivatives thereof, independently of each other and in place of some or all of them. You may.

Examples of polymerizable ester-forming derivatives of compounds having a carboxy group, such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids, include esters, acid halides and acid anhydrides.
Examples of the ester-forming derivative include those obtained by converting a carboxy group into an alkoxycarbonyl group or an aryloxycarbonyl group.
Examples of the acid halide include those obtained by converting a carboxy group into a haloformyl group.
Examples of the acid anhydride include those obtained by converting a carboxy group into an acyloxycarbonyl group.

Examples of polymerizable derivatives of compounds having a hydroxy group, such as aromatic hydroxycarboxylic acids, aromatic diols and aromatic hydroxyamines, are those obtained by acylating a hydroxy group into an acyloxy 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).

Among the polymerizable ester-forming derivatives exemplified, as the raw material monomer of the liquid crystal polyester, an acylated product obtained by acylating an aromatic hydroxycarboxylic acid or an aromatic diol is preferable.

The liquid crystal polyester used in this embodiment is represented by the repeating unit (u1) represented by the following formula (2), the repeating unit (u2) represented by the following formula (3), and the following formula (4). A resin having a repeating unit (u3) is preferable.

-O-Ar ^1- CO- (2)
-CO-Ar ^2- CO- ... (3)
-X-Ar ^3- Y- (4)
In the formula, Ar ¹ , Ar ² and Ar ³ independently represent a phenylene group, a naphthylene group or a biphenylylene group, respectively. However, the hydrogen atom contained in these phenylene group, naphthylene group or biphenylylene group may be substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. X and Y each independently represent an oxygen atom or an imino group (-NH-).

Examples of the halogen atom that can be replaced with a hydrogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of the alkyl group having 1 to 10 carbon atoms that can be replaced with a hydrogen atom include a methyl group, an ethyl group, a 1-propyl group, an isopropyl group, a 1-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Examples thereof include 1-hexyl group, 2-ethylhexyl group, 1-octyl group and 1-decyl group.

Examples of the aryl group having 6 to 20 carbon atoms that can be substituted with a hydrogen atom include a monocyclic aromatic group such as a phenyl group, an orthotolyl group, a methatril group, and a paratril group; Examples thereof include fused ring aromatic groups such as.

When one or more hydrogen atoms are substituted with the above-mentioned substituents in the phenylene group, naphthylene group or biphenylylene group represented by Ar ¹ , Ar ² or Ar ³ , the number of the substituents is Ar ^1. , Ar ² or Ar ³ is preferably one or two independently of each other. Further, the number of the substituents is more preferably 1 for each group represented by Ar ¹ , Ar ² or Ar ³ .

The repeating unit (u1) is a repeating unit derived from a predetermined aromatic hydroxycarboxylic acid.

In addition, in this specification, "origin" means that the chemical structure is changed due to the polymerization of the raw material monomer, and no other structural change occurs.

Examples of the aromatic hydroxycarboxylic acid include 4-hydroxybenzoic acid, metahydroxybenzoic acid, 2-hydroxy-6-naphthoic acid, 2-hydroxy-3-naphthoic acid, 1-hydroxy-5-naphthoic acid, 4 -Hydroxy-4'-carboxydiphenyl ether, or a part of the hydrogen atom in the aromatic ring of these aromatic hydroxycarboxylic acids, is substituted with a substituent selected from the group consisting of an alkyl group, an aryl group and a halogen atom. Aromatic hydroxycarboxylic acid can be mentioned.

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

As the repeating unit (u1), Ar ¹ is a 1,4-phenylene group (repeating unit derived from 4-hydroxybenzoic acid), and Ar ¹ is a 2,6-naphthylene group (2-hydroxy-). A repeating unit derived from 6-naphthoic acid) is preferred. Among these, the repeating unit (u1) is a repeating unit in which Ar ¹ is a 2,6-naphthylene group (2-hydroxy-6-naphthoic acid) from the viewpoint of facilitating the growth of crystallites. ) Is more preferable.

The repeating unit (u2) is a repeating unit derived from a predetermined aromatic dicarboxylic acid.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, biphenyl-4,4'-dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, and diphenylthioether-4,4. '-Dicarboxylic acid, or an aromatic dicarboxylic acid in which a part of hydrogen atoms in the aromatic ring of these aromatic dicarboxylic acids is substituted with a substituent selected from the group consisting of an alkyl group, an aryl group and a halogen atom. Can be mentioned.

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

As the repeating unit (u2), Ar ² is a 1,4-phenylene group (for example, a repeating unit derived from terephthalic acid), and Ar ² is a 1,3-phenylene group (for example, isophthalic acid). Derived repeating unit), Ar ² having a 2,6-naphthylene group (eg, a repeating unit derived from 2,6-naphthalenedicarboxylic acid), Ar ² having a diphenyl ether-4,4'-diyl group. (For example, a repeating unit derived from a diphenyl ether-4,4'-dicarboxylic acid) is preferred. Among these, as the repeating unit (u2), from the viewpoint of facilitating the growth of crystallites, Ar ² is a 2,6-naphthylene group (for example, a repeating unit derived from 2,6-naphthalenedicarboxylic acid). Unit) is more preferable.

The repeating unit (u3) is a repeating unit derived from a predetermined aromatic diol, aromatic hydroxyamine or aromatic diamine.

Examples of the aromatic diol, aromatic hydroxyamine or aromatic diamine include 4,4'-dihydroxybiphenyl, hydroquinone, resorcin, 4,4'-dihydroxydiphenylketone, 4,4'-dihydroxydiphenyl ether and bis (4-). Hydroxyphenyl) methane, 1,2-bis (4-hydroxyphenyl) ethane, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylthioether, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, Examples thereof include 1,5-dihydroxynaphthalene, 4-aminophenol, 1,4-phenylenediamine, 4-amino-4'-hydroxybiphenyl and 4,4'-diaminobiphenyl.

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

As the repeating unit (u3), Ar ³ is a 1,4-phenylene group (for example, a repeating unit derived from hydroquinone, 4-aminophenol or 1,4-phenylenediamine), and Ar ³ is 4,4'. Those having a −biphenylylene group (for example, a repeating unit derived from 4,4'-dihydroxybiphenyl, 4-amino-4'-hydroxybiphenyl or 4,4'-diaminobiphenyl) are preferable.

When the molded product obtained from the liquid crystal polyester of the present embodiment is particularly required to have good heat resistance and thermal stability, the repeating units (u1) to (u3) have a smaller number of substituents. Is preferable. Further, when the molded product obtained from the liquid crystal polyester of the present embodiment is particularly required to have good heat resistance and thermal stability, it is preferable that the molded product does not have a heat-sensitive substituent (for example, an alkyl group).

In the present embodiment, the heat resistance of the molded product means the property that the resin, which is the material for forming the molded product, does not easily soften. In the present embodiment, the heat resistance of the molded product can be clarified by measuring the deflection temperature under load of the resin. The deflection temperature under load in this embodiment is measured under a load of 1.82 MPa according to ASTM D648. It can be said that the higher the deflection temperature under load of the resin measured in this way, the higher the heat resistance of the molded product.

Further, in the present embodiment, the thermal stability of the molded product means a property that the resin is less likely to be decomposed or deteriorated when the molded product is held at the temperature at which the resin is molded (melting temperature).

Specific examples of the preferable liquid crystal polyester used in the present embodiment include a polymer composed of a combination of the following monomer constituent units.
(A) 2-Hydroxy-6-naphthoic acid / hydroquinone / 2,6-naphthalenedicarboxylic acid / terephthalic acid copolymer (b) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / 4,4'- Dihydroxybiphenyl / terephthalic acid copolymer (c) 4-hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid copolymer (d) 2-hydroxy-6-naphthoic acid / terephthalic acid / hydroquinone copolymer (e) 2-Hydroxy-6-naphthoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl copolymer (f) 4-hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / terephthalic acid / hydroquinone copolymer (g) 4-Hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / terephthalic acid / hydroquinone / 4,4'-dihydroxybiphenyl copolymer (h) 4-hydroxybenzoic acid / 2,6-naphthalenedicarboxylic acid / 4,4 '-Dihydroxybiphenyl copolymer (i) 4-hydroxybenzoic acid / terephthalic acid / 2,6-naphthalenedicarboxylic acid / hydroquinone copolymer (j) 4-hydroxybenzoic acid / 2,6-naphthalenedicarboxylic acid / hydroquinone Polymer (k) 4-hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / 2,6-naphthalenedicarboxylic acid / hydroquinone copolymer (l) 4-hydroxybenzoic acid / terephthalic acid / 2,6-naphthalenedicarboxylic acid Acid / Hydroquinone / 4,4'-dihydroxybiphenyl copolymer (m) 2-hydroxy-6-naphthoic acid / terephthalic acid / 4-aminophenol copolymer (n) 4-hydroxybenzoic acid / 2-hydroxy-6 -Naphthalic acid / terephthalic acid / 4-aminophenol copolymer (o) 4-hydroxybenzoic acid / 2-hydroxy-6-naphthoic acid / terephthalic acid / ethylene glycol copolymer (p) 4-hydroxybenzoic acid / 2 -Hydroxy-6-naphthoic acid / terephthalic acid / 4,4'-dihydroxybiphenyl / ethylene glycol copolymer (q) 4-hydroxybenzoic acid / terephthalic acid / 2,6-naphthalenedicarboxylic acid / 4,4'-dihydroxy Biphenyl copolymer

Among the above examples, (a), (b), (c) and (e) are preferable, and (a) and (b) are more preferable.

The content of the repeating unit (u1) in the liquid crystal polyester is preferably 30 mol% or more, more preferably 30 mol% or more and 80 mol, based on the total amount (100 mol%) of all the repeating units constituting the liquid crystal polyester. % Or less, more preferably 35 mol% or more and 70 mol% or less, and particularly preferably 40 mol% or more and 65 mol% or less.

For the total amount of all repeating units constituting the liquid crystal polyester, the amount of substance (mol) of each repeating unit is obtained by dividing the mass of each repeating unit constituting the liquid crystal polyester by the formula amount of each repeating unit. It is the total value of them.

When the content of the repeating unit (u1) in the liquid crystal polyester is at least the lower limit of the above-mentioned preferable range, the bending strength of the liquid crystal polyester molded product of the present embodiment can be easily increased. On the other hand, when the content of the repeating unit (u1) is not more than the upper limit of the above-mentioned preferable range, the melt viscosity can be easily lowered. Therefore, the temperature required for molding the liquid crystal polyester tends to be low.

The content of the repeating unit (u2) in the liquid crystal polyester is preferably 35 mol% or less, more preferably 10 mol% or more and 35 mol, based on the total amount (100 mol%) of all the repeating units constituting the liquid crystal polyester. % Or less, more preferably 15 mol% or more and 35 mol% or less, and particularly preferably 17.5 mol% or more and 30 mol% or less.
When the content of the repeating unit (u2) in the liquid crystal polyester is at least the lower limit of the above-mentioned preferable range, the bending strength of the liquid crystal polyester molded product of the present embodiment can be easily increased. On the other hand, when the content of the repeating unit (u2) is not more than the upper limit of the above-mentioned preferable range, the melt viscosity can be easily lowered. Therefore, the temperature required for molding the liquid crystal polyester tends to be low.

The content of the repeating unit (u3) in the liquid crystal polyester is preferably 35 mol% or less, more preferably 10 mol% or more and 35 mol, based on the total amount (100 mol%) of all the repeating units constituting the liquid crystal polyester. % Or less, more preferably 15 mol% or more and 35 mol% or less, and particularly preferably 17.5 mol% or more and 30 mol% or less.

In the liquid crystal polyester, the ratio (molar ratio) of the content of the repeating unit (u2) to the content of the repeating unit (u3) is [content of the repeating unit (u2)] / [containing of the repeating unit (u3)]. Rate], preferably 0.9 / 1-1 / 0.9, more preferably 0.95 / 1-1 / 0.95, still more preferably 0.98 / 1-1 / 0.98. is there.

In the liquid crystal polyester, the ratio of the repeating units containing the 2,6-naphthylene group among the repeating units (u1) to (u3) is the ratio of the total of all the repeating units constituting the liquid crystal polyester. It is preferably 40 mol% or more, more preferably 40 mol% or more and 80 mol% or less, and further preferably 45 mol% or more and 75 mol% or less.
When the ratio of the repeating unit containing the 2,6-naphthylene group in the liquid crystal polyester is not more than the lower limit of the above-mentioned preferable range, the bending strength of the liquid crystal polyester molded product of the present embodiment can be easily increased. On the other hand, when the ratio of the repeating unit containing the 2,6-naphthylene group is not more than the upper limit of the above-mentioned preferable range, the melt viscosity can be easily lowered.

The liquid crystal polyester may have only one type of repeating units (u1) to (u3) independently of each other, or may have two or more types of repeating units (u1) to (u3).
Further, the liquid crystal polyester may have one or more repeating units other than the repeating units (u1) to (u3), but the content thereof is preferably 10 with respect to the total amount of all the repeating units. It is mol% or less, more preferably 5 mol% or less.

Factors (I), factors (II), and factors (III) illustrated below are presumed as factors that affect the crystallite size of the liquid crystal polyester molded product.

Factor (I): From the viewpoint of stacking property between aromatic rings, the repeating unit having a main skeleton of 2,6-naphthylene group is more crystalline than the repeating unit having a main skeleton of 1,4-phenylene group. Growth is easy to promote.

Factor (II): When the repeating unit [-O- (2,6-naphthylene group) -CO-] and the repeating unit [-CO- (2,6-naphthylene group) -CO-] are combined, the latter Stacking between the former is likely to be partially hindered by the presence of.
Factor (III): When the repeating unit [-O- (2,6-naphthylene group) -CO-] and the repeating unit [-CO- (2,6-naphthylene group) -CO-] are combined, heating By performing the treatment (annealing), the stacking inhibition between the former by the latter is alleviated, and it is easy to take the most stable state (that is, the crystallite size tends to increase).

The flow start temperature of the liquid crystal polyester is preferably 270 ° C. or higher, more preferably 270 to 400 ° C., and even more preferably 280 to 380 ° C. When a liquid crystal polyester having a flow start temperature in the above range is used, improvement in heat resistance and hardness of the liquid crystal polyester molded product of the present embodiment can be expected. Further, in melt molding when obtaining a liquid crystal polyester molded product, the thermal stability of the liquid crystal polyester is improved, and thermal deterioration is easily suppressed.

The flow start temperature is when the liquid crystal polyester is melted while raising the temperature at a rate of 4 ° C./min under a load of 9.8 MPa using a capillary rheometer and extruded from a nozzle having an inner diameter of 1 mm and a length of 10 mm. It is a temperature at the time of showing the viscosity of 4800 Pa · s (48000 poise).
The flow start temperature, also called the flow temperature or the flow temperature, is a measure of the molecular weight of the liquid crystal polyester (for example, edited by Naoyuki Koide, "Liquid Crystal Polymer-Synthesis / Molding / Application-", pp. 95-105, See CMC, published June 5, 1987).

The liquid crystal polyester can be produced, for example, by melt-polymerizing a raw material monomer corresponding to a repeating unit constituting the same, and solid-phase polymerizing the obtained polymer (prepolymer).

Liquid crystal polyester manufacturing method:
Next, an example of the method for producing the liquid crystal polyester in the present embodiment will be described.

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

The acylation step is a step of obtaining an acylated product by acylating a phenolic hydroxy group contained in a raw material monomer with a fatty acid anhydride (for example, acetic anhydride).

In the polymerization step, the acyl group of the acylated product obtained in the acylation step and the carboxy group of the acylated product of the aromatic dicarboxylic acid and the aromatic hydroxycarboxylic acid are polymerized so as to cause ester exchange, thereby causing liquid crystal polyester. It is good to get.

The acylation step and the polymerization step may be carried out in the presence of a complex cyclic organic base compound as represented by the following general formula (b1).

In the above formula (b1), R _{1 to} R ₄ are independently each of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxymethyl group, a cyano group, and a cyanoalkyl group having 1 to 4 carbon atoms. Group, cyanoalkoxy group having 1 to 4 carbon atoms, carboxy group, amino group, aminoalkyl group having 1 to 4 carbon atoms, aminoalkoxy group having 1 to 4 carbon atoms, phenyl group, benzyl group, phenylpropi Represents a le group or a formyl group.

The complex cyclic organic base compound represented by the above formula (b1) is preferably an imidazole derivative in which R ₁ is an alkyl group having 1 to 4 carbon atoms and R _{2 to} R ₄ are hydrogen atoms, respectively. Thereby, the reactivity of the acylation reaction in the acylation step and the transesterification reaction in the polymerization step can be further improved. In addition, the color tone of the molded product obtained by using the liquid crystal polyester composition of the present embodiment can be further improved.

Among such complex cyclic organic base compounds, one or both of 1-methylimidazole and 1-ethylimidazole are particularly preferable because they are easily available.

The amount of the heterocyclic organic base compound used is 0.005 when the total amount of the raw material monomer of the liquid crystal polyester (that is, aromatic dicarboxylic acid, aromatic diol and aromatic hydroxycarboxylic acid) is 100 parts by mass. It is preferable that the amount is ~ 1 part by mass. Further, from the viewpoint of color tone and productivity of the molded product, it is more preferable to use 0.05 to 0.5 parts by mass with respect to 100 parts by mass of the raw material monomer.

The heterocyclic organic base compound may be present at one time during the acylation reaction and the transesterification reaction, and the addition time may be immediately before the start of the acylation reaction or during the acylation reaction. It may be between the acylation reaction and the transesterification reaction. The liquid crystal polyester obtained in this manner has extremely high melt fluidity and excellent thermal stability.

The amount of fatty acid anhydride (for example, acetic anhydride) used can be determined in consideration of the amount of aromatic diol and aromatic hydroxycarboxylic acid used as raw material monomers. Specifically, the total equivalent of the phenolic hydroxy groups contained in these raw material monomers is preferably 1.0 times or more and 1.2 times or less, and 1.0 times or more and 1.15 times or less. It is more preferably 1.03 times or more, 1.12 times or less, and particularly preferably 1.05 times or more and 1.1 times or less.

When the amount of fatty acid anhydride used is 1.0 times or more the total amount of the phenolic hydroxy groups contained in the raw material monomer, the acylation reaction is likely to proceed, and the unreacted raw material monomer is likely to proceed in the subsequent polymerization step. Is unlikely to remain, and as a result, polymerization proceeds efficiently. Further, when the acylation reaction proceeds sufficiently in this way, there is little possibility that the unacylated raw material monomer sublimates and the fractionator used at the time of polymerization is clogged. On the other hand, when the amount of the fatty acid anhydride used is 1.2 times equivalent or less, the obtained liquid crystal polyester is difficult to be colored.

The acylation reaction in the above-mentioned acylation step is preferably carried out in a temperature range of 130 to 180 ° C. for 30 minutes to 20 hours, and more preferably carried out at 140 to 160 ° C. for 1 to 5 hours.

The aromatic dicarboxylic acid used in the above-mentioned polymerization step may be present in the reaction system during the acylation step. That is, in the acylation step, the aromatic diol, the aromatic hydroxycarboxylic acid and the aromatic dicarboxylic acid may be present in the same reaction system. This is because neither the carboxy group in the aromatic dicarboxylic acid and the optionally substituted substituent is affected by the fatty acid anhydride.

Therefore, a method in which the acylation step and the polymerization step are sequentially performed after charging the aromatic diol, the aromatic hydroxycarboxylic acid and the aromatic dicarboxylic acid into the reactor may be used, or the aromatic diol and the aromatic dicarboxylic acid may be used in the reactor. It is also possible to carry out a polymerization step by further charging an aromatic dicarboxylic acid into a reactor after charging and performing an acylation step. The former method is preferable from the viewpoint of simplifying the manufacturing process.

The transesterification reaction in the above-mentioned polymerization step is preferably carried out while raising the temperature from 130 ° C. to 400 ° C. at a heating rate of 0.1 to 50 ° C./min, and 150 at a heating rate of 0.3 to 5 ° C./min. It is more preferable to carry out the process while raising the temperature from ° C. to 350 ° C.

In addition, when the transesterification reaction in the polymerization step is carried out, in order to shift the equilibrium, by-produced fatty acids (such as acetic acid) and unreacted fatty acid anhydrides (such as acetic anhydride) are evaporated to the outside of the system. It is preferable to distill off. At this time, by refluxing a part of the distilled fatty acid and returning it to the reactor, the raw material monomer or the like that evaporates or sublimates with the fatty acid can be condensed or reverse sublimated and returned to the reactor.

In the acylation reaction in the acylation step and the transesterification reaction in the polymerization step, a batch device may be used as the reactor, or a continuous device may be used. A liquid crystal polyester that can be used in the present embodiment can be obtained by using any of the reaction devices.

After the above-mentioned polymerization step, a step for increasing the molecular weight of the liquid crystal polyester obtained in this polymerization step may be performed. For example, if the liquid crystal polyester obtained in the polymerization step is cooled and then pulverized to produce a powdery liquid crystal polyester, and the powder is further heated, the liquid crystal polyester can be made higher in molecular weight. Is.

Further, a pellet-shaped liquid crystal polyester is produced by granulating the powdered liquid crystal polyester obtained by cooling and crushing, and then the pellet-shaped liquid crystal polyester is heated to increase the molecular weight of the liquid crystal polyester. May be good. Higher molecular weights using these methods are referred to in the art as solid phase polymerization.

Solid phase polymerization is particularly effective as a method for increasing the molecular weight of liquid crystal polyester. By increasing the molecular weight of the liquid crystal polyester, it becomes easy to obtain a liquid crystal polyester having a suitable flow start temperature as described later.

As the reaction conditions for solid phase polymerization, it is preferable to heat-treat the resin in a solid state under an inert gas atmosphere or under reduced pressure at a reaction temperature of 265 to 325 ° C., preferably 270 to 320 ° C. for 1 to 20 hours.
The temperature from room temperature to the reaction temperature is preferably raised over 3 to 20 hours, and the temperature may be raised in multiple steps. Examples of the device used for the heat treatment include known dryers, reactors, inert ovens, and electric furnaces.

In addition to the liquid crystal polyester, the liquid crystal polyester molded product of the present embodiment may be further blended with other components such as a filler, a resin other than the liquid crystal polyester, and other additives to form a composition. Examples of this additive include components usually used in resin compositions, such as stabilizers, ultraviolet absorbers, plasticizers, flame retardants, flame retardants, antistatic agents, surfactants, colorants, and lubricants. And so on. The other components may be one kind or two or more kinds.

As a method for producing the liquid crystal polyester molded product of the present embodiment, for example, a melt molding method is preferably mentioned. Examples of this melt molding method include an injection molding method, a T-die method, an extrusion molding method such as an inflation method; a compression molding method, a blow molding method, a vacuum forming method, and a press molding, and among these, an injection molding method. Is preferable.

In the case of the injection molding method, it is preferable to carry out the method for the purpose of growing crystallites of the liquid crystal polyester, for example, under the conditions illustrated below.

The preferable temperature condition at the time of molding is that the temperature difference between the nozzle side (C1) and the rear part of the cylinder (C5) is, for example, 40 to 80 ° C, preferably 50 to 75 ° C.
When the temperature difference of each part during molding is within the above range, the crystallites that can be crystal nuclei are held in the cylinder of the molding machine without melting, which is preferable from the viewpoint of crystal growth.

The preferable injection speed condition at the time of molding is preferably 150 mm / sec or more, preferably 200 mm / sec or more. When the injection speed is in the above range, it is preferable from the viewpoint of the filling property of the member constituting the product into the ultra-thin portion and the orientation of the crystallites of the liquid crystal polyester.

The temperature of the mold is preferably 100 ° C. or higher in order to promote crystal growth in the cooling step from the molten state.

Further, as described above, for the purpose of growing crystallites of the liquid crystal polyester, a molding material may be filled in a mold, molded, and then heat-treated.

For the heat treatment, a commonly known method can be adopted. For example, a method of heating the molded product by applying hot air and a method of heating by irradiating far infrared rays can be mentioned, and a method of irradiating far infrared rays is preferable. When the heat treatment of the molded product is performed by irradiation with far infrared rays, the far infrared rays reach the inside of the molded product. In this case, since the heat treatment can be performed not only from the surface of the molded body but also from the inside, the molded body is heat-treated to the same extent on the surface and the inside. In addition, in the case of heat treatment using far infrared rays, the molded product can be heated to a desired heat treatment temperature in a short time. In this case, since the heat treatment can be completed in a short treatment time, high productivity can be realized.

The heat treatment temperature is preferably in a temperature range of 20 ° C. lower (Tm-20 ° C.) or higher than the melting point (Tm) of the molded product and lower than the melting point of the molded product. By heat-treating under such temperature conditions, a molded product in which the growth of the crystallite size of the molded product is enhanced can be obtained even though the heat treatment is performed at a temperature lower than the melting point of the temporary molded product.
The heat treatment temperature may be constant or changed during the heat treatment as long as it is within the temperature range of Tm-20 ° C. or higher and lower than the melting point of the molded product.

Examples of the product or component which is the liquid crystal polyester molded product of the present embodiment include electrical / electronic components and optical components. Specific examples thereof include IMM, DDR, CPU sockets, S / O, DIMMs, Board to Board connectors, FPC connectors, card connectors and other connectors, sockets, relay cases, relay bases, rerace proofs, relay armatures and other relays. Parts, coil bobbins such as optical pickup bobbins and trans bobbins, oscillators, printed wiring boards, circuit boards, semiconductor packages, computer-related parts, camera barrels, optical sensor housings, compact camera module housings (packages, lens barrels), Semiconductor manufacturing process-related parts such as projector optical engine components, IC trays, wafer carriers; household electrical product parts such as VTRs, TVs, irons, air conditioners, stereos, vacuum cleaners, refrigerators, rice cookers, lighting fixtures; lamp reflectors, LEDs Lighting equipment parts such as reflectors and lamp holders; acoustic product parts such as compact disks, laser disks (registered trademarks), and speakers; communication equipment parts such as ferrules for optical cables, telephone parts, facsimile parts, and modems.

The liquid crystal polyester molded product of the present embodiment has higher bending strength. Taking advantage of this characteristic, the liquid crystal polyester molded product of the present embodiment can be preferably used for a part having an ultra-thin portion having a particularly thin thickness. Among them, the liquid crystal polyester molded product of the present embodiment can be preferably used for a connector.

As described above, in the liquid crystal polyester molded product of the present embodiment, the crystallite size at the center of the molded product is larger than the conventional one, and is 120 × 10 ^-10 m or more. According to such a liquid crystal polyester molded body, the bending strength of the ultra-thin portion of the member constituting the product is further enhanced, and the mechanical properties of the member such as the connector can be further improved.

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.

<Manufacturing of liquid crystal polyester molded product>
The liquid crystal polyester (1), the liquid crystal polyester (2), and the liquid crystal polyester (3) shown below were used, respectively.

Manufacture of liquid crystal polyester (1):
A reactor equipped with a stirrer, torque meter, nitrogen gas introduction tube, thermometer and reflux cooler, 6-hydroxy-2-naphthoic acid (1034.99 g, 5.5 mol) and 2,6-naphthalenedicarboxylic acid. Total of acid (378.33 g, 1.75 mol), terephthalic acid (83.07 g, 0.5 mol), hydroquinone (272.52 g, 2.475 mol, 2,6-naphthalenedicarboxylic acid and terephthalic acid) 0.225 mol excess with respect to the amount) and anhydrous acetic acid (1226.87 g, 12 mol) were charged. After replacing the gas in the reactor with nitrogen gas, 0.17 g of 1-methylimidazole was added, and the temperature was raised from room temperature to 145 ° C. over 15 minutes with stirring under a nitrogen gas stream, and 1 at 145 ° C. It was refluxed for hours.
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, then the contents were taken out and cooled to room temperature. did. The obtained solid material is pulverized with a pulverizer to a particle size of about 0.1 to 1 mm, heated in a nitrogen atmosphere from room temperature to 250 ° C. over 1 hour, and then raised from 250 ° C. to 310 ° C. over 10 hours. Solid phase polymerization was carried out by warming and holding at 310 ° C. for 5 hours. The obtained solid phase polymer was cooled to room temperature to obtain a liquid crystal polyester (1).
The liquid crystal polyester (1) has a repeating unit (u11) in which Ar ¹ is a 2,6-naphthylene group, a repeating unit (u21) in which Ar ² is a 2,6-naphthylene group, and Ar ^{2 in the} molecule. It had a repeating unit (u22) which was a 4-phenylene group and a repeating unit (u31) in which Ar ³ was a 1,4-phenylene group, and the flow start temperature thereof was 324 ° C.

After drying the liquid crystal polyester (1) at 120 ° C. for 5 hours, a water-sealed vacuum pump Shinko Seiki Co., Ltd. is used with a twin-screw extruder with a vacuum vent (“PCM-30” manufactured by Ikekai Iron Works Co., Ltd.). Using the company's "SW-25S", while degassing with a vacuum vent, melt and knead under the conditions of a cylinder temperature of 340 ° C and a screw rotation speed of 150 rpm, and strands are passed through a circular nozzle (discharge port) with a diameter of 3 mm. It was discharged in a shape. Next, the discharged kneaded product was passed through a water bath at a water temperature of 30 ° C. for 1.5 seconds, and then pelletized with a strand cutter (manufactured by Tanabe Plastic Machinery Co., Ltd.) to pelletize the liquid crystal polyester (1). I got it in.

Manufacture of liquid crystal polyester (2):
P-Hydroxybenzoic acid (994.5 g, 7.20 mol) and terephthalic acid (272.1 g, 1.20 mol) in a reactor equipped with a stirrer, torque meter, nitrogen gas introduction tube, thermometer and reflux condenser. 64 mol), isophthalic acid (126.6 g, 0.76 mol), 4,4'-dihydroxybiphenyl (446.9 g, 2.40 mol), and 1347.6 g (13.20 mol) anhydrous acetic acid. Was prepared. After replacing the gas in the reactor with nitrogen gas, 0.18 g of 1-methylimidazole was added, and the temperature was raised from room temperature to 150 ° C. over 30 minutes while stirring under a nitrogen gas stream, and the temperature was raised to 30 at 150 ° C. Refluxed for minutes.
Then, after adding 2.40 g of 1-methylimidazole, the temperature was raised from 150 ° C. to 320 ° C. over 2 hours and 50 minutes while distilling off by-produced acetic acid and unreacted acetic anhydride, and the torque increased. When it was observed, the reaction was terminated, the contents were taken out from the reactor, and the mixture was cooled to room temperature. Next, this prepolymer is pulverized using a pulverizer, and the obtained pulverized product is heated from room temperature to 250 ° C. over 1 hour in a nitrogen gas atmosphere, and then heated from 250 ° C. to 280 ° C. over 5 hours. Then, solid phase polymerization was carried out by holding at 280 ° C. for 3 hours. The obtained solid phase polymer was cooled to room temperature to obtain a liquid crystal polyester (2).
The liquid crystal polyester (2) has a repeating unit (u12) in which Ar ¹ is a 1,4-phenylene group, a repeating unit (u22) in which Ar ² is a 1,4-phenylene group, and Ar ² is 1. It has a repeating unit (u23) which is a 3-phenylene group and a repeating unit (u32) in which Ar ³ is a 4,4'-biphenylylene group, and the flow start temperature thereof is 312 ° C.

After drying the liquid crystal polyester (2) at 120 ° C. for 5 hours, a water-sealed vacuum pump Shinko Seiki Co., Ltd. is used with a twin-screw extruder with a vacuum vent (“PCM-30” manufactured by Ikekai Iron Works Co., Ltd.). Using the company's "SW-25S", while degassing with a vacuum vent, melt and knead under the conditions of a cylinder temperature of 340 ° C and a screw rotation speed of 150 rpm, and strands are passed through a circular nozzle (discharge port) with a diameter of 3 mm. It was discharged in a shape. Next, the discharged kneaded product was passed through a water bath at a water temperature of 30 ° C. for 1.5 seconds, and then pelletized with a strand cutter (manufactured by Tanabe Plastic Machinery Co., Ltd.) to pelletize the liquid crystal polyester (2). I got it in.

Manufacture of liquid crystal polyester (3):
P-Hydroxybenzoic acid (33.15 g, 0.24 mol) and 6-hydroxy-2-naphthoic acid (33.15 g, 0.24 mol) in a reactor equipped with a stirrer, torque meter, nitrogen gas introduction tube, thermometer and reflux condenser. 1083.92 g, 5.76 mol), terephthalic acid (498.39 g, 3.00 mol), 4,4'-dihydroxybiphenyl (558.63 g, 3.00 mol), and acetic anhydride (1347.59 g). , 13.20 mol) and was charged. After replacing the gas in the reactor with nitrogen gas, 0.22 g of 1-methylimidazole was added, and the temperature was raised from room temperature to 150 ° C. over 30 minutes with stirring under a nitrogen gas stream, and 1 at 150 ° C. It was refluxed for hours.
Next, while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was raised from 150 ° C. to 335 ° C. over 4.5 hours, and when an increase in torque was observed, the reaction was terminated and the contents were removed from the reactor. The material was taken out and cooled to room temperature. The obtained solid material is pulverized with a pulverizer to a particle size of about 0.1 to 1 mm, heated from room temperature to 250 ° C. over 1 hour under a nitrogen atmosphere, and then raised from 250 ° C. to 300 ° C. over 5 hours. Solid phase polymerization was carried out by warming and holding at 300 ° C. for 3 hours. The obtained solid phase polymer was cooled to room temperature to obtain a liquid crystal polyester (3).
The liquid crystal polyester (3) has a repeating unit (u12) in which Ar ¹ is a 1,4-phenylene group, a repeating unit (u11) in which Ar ¹ is a 2,6-naphthylene group, and Ar ^{2 in the} molecule. It has a repeating unit (u22) which is a 4-phenylene group and a repeating unit (u32) in which Ar ³ is a 4,4'-biphenylylene group, and the flow start temperature thereof is 338 ° C.

After drying the liquid crystal polyester (3) at 120 ° C. for 5 hours, a water-sealed vacuum pump Shinko Seiki Co., Ltd. is used with a twin-screw extruder with a vacuum vent (“PCM-30” manufactured by Ikekai Iron Works Co., Ltd.). Using the company's "SW-25S", while degassing with a vacuum vent, melt and knead under the conditions of a cylinder temperature of 350 ° C. and a screw rotation speed of 150 rpm, and strands are passed through a circular nozzle (discharge port) with a diameter of 3 mm. It was discharged in a shape. Next, the discharged kneaded product was passed through a water bath at a water temperature of 30 ° C. for 1.5 seconds, and then pelletized with a strand cutter (manufactured by Tanabe Plastic Machinery Co., Ltd.) to pelletize the liquid crystal polyester (3). I got it in.

FIG. 1 is a perspective view showing a mold (a mold for measuring a thin-walled flow length) used when manufacturing a liquid crystal polyester molded product. The unit of the numerical value in FIG. 1 is mm.
When producing the liquid crystal polyester molded product, a mold having a thickness of X mm (X = 0.08, 0.10), which has the same form as the mold shown in FIG. 1, was used.

Further, as a molding machine, an injection molding machine (Robot S2000i-30B manufactured by FANUC Corporation) was used. The injection molding conditions for producing the liquid crystal polyester molded product were set as follows.
[Injection molding conditions]
The temperature on the nozzle side is referred to as C1, and the cylinder temperature from the nozzle side to the bottom of the hopper is referred to as C1 / C2 / C3 / C4 / C5 / HP.
Cylinder temperature: C1 / C2 / C3 / C4 / C5 / HP = 350/350/330/310/280/80 ° C (in the case of liquid crystal polyester (1), liquid crystal polyester (2))
Cylinder temperature: C1 / C2 / C3 / C4 / C5 / HP = 370/370/350/330/310/80 ° C (in the case of liquid crystal polyester (3))
Mold temperature: 120 ° C
Weighing value: 20 mm
Injection speed: 200 mm / sec (Test Examples 1, 2, 4-9), 300 mm / sec (Test Example 3)
VP switching: Pressure switching at 150 MPa Holding pressure: 20 MPa

(Test Example 1)
Under the above [injection molding conditions], the molten liquid crystal polyester (1) was supplied from the injection molding machine into the mold through the gate of the mold having the same form as that shown in FIG.
Next, the liquid crystal polyester (1) solidified in the mold is taken out, and in a non-oxidizing atmosphere incubator (Incubator IPHH-201 (ESPEC)) under a nitrogen atmosphere, it takes 1 hour from room temperature to 250 ° C. The temperature was raised from 250 ° C. to 310 ° C. over 6 hours, and heat treatment was performed at 310 ° C. for 5 hours to obtain a liquid crystal polyester molded product (1) having a thickness of 0.08 mmt.

(Test Example 2)
A liquid crystal polyester molded product (2) having a thickness of 0.10 mmt was obtained in the same manner as in Test Example 1 except that the thickness of the mold was changed.

(Test Example 3)
Under the above [injection molding conditions], the molten liquid crystal polyester (3) is supplied into the mold from the gate of the mold having the same form as that shown in FIG. 1 from the injection molding machine and solidified to obtain a thickness. A 0.08 mmt liquid crystal polyester molded product (3) was obtained.

(Test Example 4)
A liquid crystal polyester molded product (4) having a thickness of 0.10 mmt was obtained in the same manner as in Test Example 3 except that the thickness of the mold was changed.

(Test Example 5)
A liquid crystal polyester molded product (5) having a thickness of 0.08 mmt was obtained in the same manner as in Test Example 3 except that the liquid crystal polyester (3) was changed to the liquid crystal polyester (1).

(Test Example 6)
A liquid crystal polyester molded product (6) having a thickness of 0.08 mmt was obtained in the same manner as in Test Example 5 except that the liquid crystal polyester (1) was changed to the liquid crystal polyester (2).

(Test Example 7)
A liquid crystal polyester molded product (7) having a thickness of 0.08 mmt was obtained in the same manner as in Test Example 1 except that the liquid crystal polyester (1) was changed to the liquid crystal polyester (2).

(Test Example 8)
A liquid crystal polyester molded product (8) having a thickness of 0.10 mmt was obtained in the same manner as in Test Example 4 except that the liquid crystal polyester (3) was changed to the liquid crystal polyester (2).

(Test Example 9)
A liquid crystal polyester molded product (9) having a thickness of 0.10 mmt was obtained in the same manner as in Test Example 2 except that the liquid crystal polyester (1) was changed to the liquid crystal polyester (2).

Of Test Examples 1 to 9, the liquid crystal polyester molded body (1) of Test Example 1, the liquid crystal polyester molded body (2) of Test Example 2, the liquid crystal polyester molded body (3) of Test Example 3, and Test Example 4 The liquid crystal polyester molded body (4) corresponds to an example to which the present invention is applied.

<Evaluation>
For the liquid crystal polyester molded bodies (1) to (9) of each example, the crystallite size at the center of the molded body is measured, the average crystallite size of the entire molded body is measured, the bending strength is evaluated, and the solder is used by the methods shown below. The heat resistance was evaluated respectively.

[Measurement of crystallite size at the center of the molded product and average crystallite size of the entire molded product]
X-ray diffraction measurements on the liquid crystal polyester moldings of each example were performed using the beamline BL03XU (FSBL second hatch, beam size 1 μm, detector Pilatus) of the large synchrotron radiation facility SPring-8.
A test piece having a thickness of 80 μm and a test piece having a thickness of 100 μm were cut out from the obtained liquid crystal polyester molded articles of each example, and a sample for measurement was prepared.

Step (1): to the sample at a test strip, the X-ray wavelength 1 × ^{10 -10} m, the thickness direction of the test piece (distance from the outermost surface of the molded body 0～80Myuemu, distance 0～100Myuemu) Was continuously irradiated at 2 μm intervals.
Procedure (2): The diffraction peak of 110 planes derived from the liquid crystal polyester was determined.
Procedure (3): The full width at half maximum (β) of the determined diffraction peak of the 110 plane was determined.
Procedure (4): Next, the crystallite size was determined from Scherrer's equation represented by the following equation (1). D = K · λ / βcosθ ・ ・ ・ (1) In the equation, D is the crystallite size, λ is the measured X-ray wavelength, β is the half width (radian), and θ is the diffraction angle. K is a Scherrer constant (0.94).

Procedure (5): Next, the crystallite size distribution in the thickness direction of the test piece was calculated. The value of the crystallite size at the center of the test piece in the thickness direction was defined as the "crystallite size at the center of the molded product". The average value of the crystallite size of the entire test piece in the thickness direction was calculated to obtain the "average crystallite size of the entire molded product". These results are shown in Table 1.

FIG. 2 shows the relationship between the distance from the outermost surface of the molded product and the crystallite size (type of liquid crystal polyester) for each liquid crystal polyester molded product (thickness 0.08 mmt) of Test Example 3, Test Example 5, and Test Example 6. It is a figure which shows the difference).

FIG. 3 shows the distance from the outermost surface and the crystallite size of the liquid crystal polyester molded product (thickness 0.08 mmt) of Test Example 3 and the liquid crystal polyester molded product (thickness 0.10 mmt) of Test Example 4. It is a figure which shows the relationship (the difference in the thickness of a molded body). It can be confirmed that there is almost no difference depending on the thickness of the molded product.

FIG. 4 shows the relationship between the distance from the outermost surface of the molded product and the crystallite size (difference in the presence or absence of heat treatment) for each liquid crystal polyester molded product (thickness 0.08 mmt) of Test Example 1 and Test Example 5. It is a figure which shows.

[Evaluation of bending strength]
A test piece having a width of 5 mm and a length of 10 mm was cut out from the obtained liquid crystal polyester molded product of each example.
For this test piece, a precision load measuring instrument (MODEL-1605 II VL manufactured by Aiko Engineering Co., Ltd.) was used, the test speed was 10 mm / min, and the distance between fulcrums was "16 times the thickness of the test piece (thickness 0. A three-point bending test was performed five times with an indenter width of 1 mm and 1.3 mm in the case of 08 mmt and 1.6 mm in the case of a thickness of 0.10 mmt, and the average value was taken as the bending strength. The results are shown in Table 1.

[Evaluation of solder heat resistance]
A test piece having a width of 5 mm and a length of 5 mm was cut out from the obtained liquid crystal polyester molded product of each example. This test piece was immersed in a solder bath heated to 280 ° C. for 10 seconds. Then, the test piece after such immersion was taken out from the solder bath, and the presence or absence of deformation in the test piece was confirmed to evaluate the solder heat resistance.
Those in which deformation was not confirmed in the test piece were marked with "○", and those in which deformation was confirmed in the test piece were marked with "x". The results are shown in Table 1.

When the thickness of the molded product is 0.08 mmt:
From the comparison between Test Example 3 and Test Example 5 and the comparison between Test Example 3 and Test Example 6, the molded product using the liquid crystal polyester (3) was molded using the liquid crystal polyesters (1) and (2). It can be confirmed that the crystallite size at the center of the molded body is larger and the bending strength is higher than that of the body (see FIG. 2).
Further, from the comparison between Test Example 1 and Test Example 5 and the comparison between Test Example 6 and Test Example 7, by using the liquid crystal polyester (1), crystals grow by heat treatment and the bending strength is further increased. It can be confirmed that this is possible (see FIG. 4).

When the thickness of the molded product is 0.10 mmt:
From the comparison between Test Example 4 and Test Example 8, the molded product using the liquid crystal polyester (3) has a larger crystallite size at the center of the molded product than the molded product using the liquid crystal polyester (2). , It can be confirmed that the bending strength is high.

Claims (5)

It is a molded product of liquid crystal polyester.
A liquid crystal polyester molded product in which the crystallite size at the center of the molded product calculated from the crystallite size obtained by the following [method for measuring crystallite size] is 120 × 10 ⁻¹⁰ m or more.
[Measurement method of crystallite size]
The crystallite size of the liquid crystal polyester molded product is determined by the following equation (1) based on the diffraction peak of 110 planes in the X-ray diffraction spectrum measured by the wide-angle X-ray diffraction method using X-rays having a wavelength of 1 × 10 ⁻¹⁰ m. ) Is obtained from the Scherrer equation.
D = K · λ / βcosθ ・ ・ ・ (1)
In the equation, D is the crystallite size, λ is the measured X-ray wavelength, β is the full width at half maximum (radian), θ is the diffraction angle, and K is the Scherrer constant (0.94). Further, the liquid crystal polyester molded product according to claim 1, wherein the average crystallite size of the entire molded body calculated from the crystallite size obtained by the above [method for measuring crystallite size] is 100 × 10 ⁻¹⁰ m or more. .. The liquid crystal polyester has a repeating unit (u1) represented by the following formula (2), a repeating unit (u2) represented by the following formula (3), and a repeating unit (u3) represented by the following formula (4). ) And
Among the repeating units (u1) to (u3), the proportion of the repeating unit containing a 2,6-naphthylene group is 40 mol% or more with respect to the total proportion of all the repeating units constituting the liquid crystal polyester. The liquid crystal polyester molded product according to claim 1 or 2.
-O-Ar ^1- CO- (2)
-CO-Ar ^2- CO- ... (3)
-X-Ar ^3- Y- (4)
In the formula, Ar ¹ , Ar ² and Ar ³ independently represent a phenylene group, a naphthylene group or a biphenylylene group, respectively. However, the hydrogen atom contained in these phenylene group, naphthylene group or biphenylylene group may be substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. X and Y each independently represent an oxygen atom or an imino group (-NH-). A liquid crystal polyester molded product having at least one side length of 0.1 mmt or less.
In the direction of 0.1 mmt of a molded product of 5 mm × 10 mm × 0.1 mmt, the crystallite size at the center of the molded product calculated from the crystallite size obtained by the above [method for measuring crystallite size] is 120 × 10 ^−. The liquid crystal polyester molded product according to any one of claims 1 to 3, which is ¹⁰ m or more and 180 × 10 ^-10 m or less. The connector made of the liquid crystal polyester molded product according to any one of claims 1 to 4.

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