TWI797317B - Liquid crystalline polyester composition and molded article - Google Patents

Abstract

Provided is a liquid crystalline polyester composition including a liquid crystalline polyester, first carbon black, and optionally, second carbon black, wherein the first carbon black satisfies the following conditions (A) and (B), the second carbon black does not satisfy at least one of the following condition (A) and (B), the content W₁ of the first carbon black is 1 to 10 parts by mass with respect to 100 parts by mass of the liquid crystal polyester, the content of the second carbon black is 0 to 9 parts by mass with respect to 100 parts by mass of the liquid crystal polyester, and the total content of the first carbon black and the second carbon black is 1 to 10 parts by mass with respect to 100 parts by mass of the liquid crystal polyester.

(A): primary particle diameter is 10 to 50 nm

(B): DBP oil absorption amount is 300 to 550 cm³/100 g or less

Description

Liquid crystal polyester composition and molded product

The present invention relates to liquid crystal polyester compositions and molded articles thereof.

The present invention claims priority based on Japanese Patent Application No. 2018-087696 filed on April 27, 2018, so the content thereof is quoted here.

Image forming apparatuses using electrophotography, such as laser printers and photocopiers, are well known. Generally, the electrophotographic method has five steps of charging, exposure, development, transfer and fixation (also known as fixing). Specifically, first, a uniform charge is applied to the surface of the photoreceptor by corona discharge (charging step).

Next, an electrostatic image is formed by light irradiation (exposure step). The resulting electrostatic image is colored using a toner (development step). The developed electrostatic image is transferred to copy paper (transfer step). The transferred electrostatic image is fixed by heat/pressure or solvent vapor or the like (fixing step).

It is known that such image forming apparatuses and housing internal parts in electric and electronic machines can be manufactured using thermoplastic resin compositions (see, for example, Patent Document 1). The internal parts of the housing in this way are insulated.

However, static electricity may be generated when the internal parts of the housing in this manner rub against copy paper. From the transfer step to the fixation step, the toner adheres to the copy paper by electrostatic. Therefore, if the charge amount of the internal parts of the housing contacting the copy paper increases from the exposing step to the fixing step, the position of the transferred electrostatic image may be shifted. Then in a subsequent fixing step, the electrostatic image is fixed in a shifted state, thereby disturbing the resulting image.

In order to suppress an increase in the charge amount of the internal parts of the case, it is conceivable to add an additive having conductivity to the thermoplastic resin composition used to impart conductivity to the internal parts of the case.

Carbon black is known as an additive material having conductivity. Patent Document 2 discloses a liquid crystal polyester composition containing carbon black with a DBP (dibutyl phthalate) absorption of 60 to 200 cm ³ /100 g.

[Prior Technical Document] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2002-244402

[Patent Document 2] Japanese Unexamined Patent Publication No. 2001-279066

However, the liquid crystal polyester composition according to the method of Patent Document 2 cannot necessarily sufficiently suppress an increase in charge amount.

In recent years, along with the increase in speed of image formation, the conveyance speed of copy paper has gradually increased.

As the speed of conveying the copy paper increases, the charge amount of the internal parts of the casing further increases, and the noise of the image tends to increase.

Further, defects due to an increase in charge amount, in addition to occurring in image forming apparatuses, have also been confirmed in housing internal parts of electric and electronic apparatuses.

Therefore, a molded article capable of suppressing an increase in charge amount and a liquid crystalline polyester composition capable of producing such a molded article are sought.

The present invention was made in view of such circumstances, and an object of the present invention is to provide a molded article capable of suppressing an increase in charge amount, and to provide a liquid crystal polyester composition capable of producing such a molded article.

The present inventors found that, in order to suppress the increase in the charge amount, the increase in the charge amount can be suppressed as a result of adding the first carbon black satisfying the following conditions (A) and (B) to the liquid crystal polyester.

However, as a result of in-depth studies by the inventors, it was found that if the absolute value of the charge amount of the internal parts of the housing between the exposure step and the fixing step is too low, even the static electricity required for image formation on the copy paper is removed, making the transfer Static images are blurred.

The inventors set the upper limit of the content of the first carbon black and the upper limit of the content of carbon black containing the first carbon black in order to control the absolute value of the charge, and found that the absolute value of the charge can be adjusted, and then The present invention has been accomplished.

One aspect of the present invention provides a liquid crystal polyester composition, which contains liquid crystal polyester and carbon black, wherein the carbon black is the first carbon black that satisfies the following conditions (A) and (B), and is not The second carbon black that satisfies at least one of the conditions (A) and (B) constitutes, relative to 100 parts by mass of the liquid crystal polyester, the content of the carbon black is not less than 1 mass part and not more than 10 mass parts; relative to the liquid crystal polyester For 100 parts by mass, the content _W1 of the first carbon black is not less than 1 part by mass and not more than 10 parts by mass; for 100 parts by mass of the liquid crystal polyester, the content of the second carbon black is not less than 0 parts by mass and not more than 9 parts by mass.

(A): The primary particle diameter is not less than 10 nm and not more than 50 nm.

(B): The DBP oil absorption is not less than 300 cm ³ /100 g and not more than 550 cm ³ /100 g.

The BET specific surface area of the first carbon black can be configured to be not less than 500 m ² /g and not more than 1500 m ² /g.

In one aspect of the present invention, a filler may be included. The filler may be a fibrous filler, and the content _W2 of the fibrous filler is not less than 10 parts by mass and not more than 130 parts by mass relative to 100 parts by mass of liquid crystal polyester.

In one aspect of the present invention, the ratio R ₁₂ represented by the following formula (S1) may be more than 1×10 ⁵ and less than 1×10 ¹¹ .

_ρ1 represents the volume resistivity of the first carbon black. _ρ2 represents the volume resistivity of the fibrous filler.

In one aspect of the present invention, a filler is included. The filler may be a platy filler, and the content _W3 of the platy filler may be 5 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of liquid crystal polyester.

In one aspect of the present invention, the ratio R ₁₃ represented by the following formula (S2) may be more than 1×10 ⁵ and less than 1×10 ¹¹ .

_ρ1 represents the volume resistivity of the first carbon black. _ρ3 represents the volume resistivity of the platy filler.

In one aspect of the present invention, it may be configured to include a filler, and the filler may be a fibrous filler or a platy filler. The content _W2 of the fibrous filler is 10 parts by mass or more and 130 parts by mass relative to 100 parts by mass of the liquid crystal polyester; the content _W3 of the platy filler is 5 parts by mass or more and 80 parts by mass relative to 100 parts by mass of the liquid crystal polyester the following.

In one aspect of the present invention, the ratio R ₁₂₃ represented by the following formula (S3) may be more than 1×10 ⁵ and less than 1×10 ¹¹ .

_ρ1 represents the volume resistivity of the first carbon black. _ρ2 represents the volume resistivity of the fibrous filler. _ρ3 represents the volume resistivity of the platy filler.

In one aspect of the present invention, the volume resistivity ρ ₂ of the fibrous filler can be constituted as 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. below m.

In one aspect of the present invention, the volume resistivity ρ ₃ of the platy filler can be constituted as 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. below m.

In one aspect of the present invention, the volume resistivity ρ ₁ of the first carbon black can be constituted as 1×10 ² Ω. 1×10 ⁷ Ω above m. below m.

In one aspect of the present invention, the flow initiation temperature of the liquid crystal polyester may be not less than 280°C and not more than 420°C.

In one aspect of the present invention, the liquid crystal polyester composition can also be composed of structural units (I) derived from aromatic hydroxycarboxylic acids, structural units (II) derived from aromatic diols, and structural units derived from aromatic diols. The structural unit (III) of carboxylic acid, relative to the total amount of all structural units of liquid crystal polyester, the content rate of structural unit (I) is 30 mole% to 80 mole%; relative to the total structure of liquid crystal polyester The total amount of units, the content of the structural unit (II) is 10 mol % to 35 mol %; the content of the structural unit (III) is 10 mol % relative to the total amount of all structural units of the liquid crystal polyester More than 35 mol% below.

In one aspect of the present invention, it can be constituted as at least one of aromatic hydroxycarboxylic acid-based p-hydroxybenzoic acid; aromatic diol-based hydroquinone and 4,4'-dihydroxybiphenyl; aromatic The dicarboxylic acid is at least one selected from the group consisting of terephthalic acid and isophthalic acid.

One aspect of the present invention provides a molded article using the above-mentioned liquid crystal polyester composition as a molding material.

In one aspect of the present invention, it can be configured as an internal part of a housing in an electric/electronic device.

In addition, the "casing internal parts" in this specification means the parts installed inside the casing.

That is, the present invention includes the following aspects.

[1] A liquid crystal polyester composition comprising a liquid crystal polyester, a first carbon black, and a second carbon black as required, the first carbon black is a carbon black that satisfies the following conditions (A) and (B) , the aforementioned second carbon black is a carbon black that does not satisfy at least one of the aforementioned condition (A) and the aforementioned condition (B).

With respect to 100 parts by mass of the liquid crystal polyester, the content _W1 of the first carbon black is not less than 1 part by mass and not more than 10 parts by mass; with respect to 100 parts by mass of the liquid crystal polyester, the content of the second carbon black is 0 parts by mass The above is 9 parts by mass or less; and the total content of the first carbon black and the second carbon black is 1 to 10 parts by mass relative to 100 parts by mass of the liquid crystal polyester.

(A): The primary particle diameter is not less than 10 nm and not more than 50 nm.

(B): The DBP oil absorption is not less than 300 cm ³ /100 g and not more than 550 cm ³ /100 g.

[2] The liquid crystal polyester composition according to [1], wherein the first carbon black has a BET specific surface area of not less than 500 m ² /g and not more than 1500 m ² /g.

[3] The liquid crystal polyester composition as described in [1] or [2], which additionally contains a filler, the filler is a fibrous filler, and relative to 100 parts by mass of the liquid crystal polyester, the amount of the fibrous filler Content _W2 is 10 mass parts or more and 130 mass parts or less.

[4] The liquid crystal polyester composition as described in [3], wherein the relationship between the volume resistivity and content of the first carbon black and the volume resistivity and content of the fibrous filler is represented by the following formula (S1): When the ratio R ₁₂ is expressed, the ratio R ₁₂ exceeds 1×10 ⁵ and is less than 1×10 ¹¹ .

(ρ₁表示前述第一碳黑之體積電阻率。ρ₂表示前述纖維狀填料之體積電阻率。W₁表示相對於前述液晶聚酯100質量份之前述第一碳黑的含量。W₂表示相對於前述液晶聚酯100質量份之前述纖維狀填料的含量。)

(ρ ₁ represents the volume resistivity of the aforementioned first carbon black. ρ ₂ represents the volume resistivity of the aforementioned fibrous filler. W ₁ represents the content of the aforementioned first carbon black relative to 100 parts by mass of the aforementioned liquid crystal polyester. _{W 2} represents Content of the aforementioned fibrous filler relative to 100 parts by mass of the aforementioned liquid crystal polyester.)

[5] The liquid crystal polyester composition as described in [1] or [2], further comprising a filler, the filler is a platy filler, and the content of the platy filler is W relative to 100 parts by mass of the liquid crystal polyester. ₃ is not less than 5 parts by mass and not more than 80 parts by mass.

[6] The liquid crystal polyester composition as described in [5], wherein the relationship between the volume resistivity and content of the aforementioned first carbon black and the volume resistivity and content of the aforementioned platy filler is expressed by the following formula (S2): When expressed as the ratio R ₁₃ , the ratio R ₁₃ exceeds 1×10 ⁵ and is less than 1×10 ¹¹ .

(ρ₁表示前述第一碳黑之體積電阻率。ρ₃表示所述板狀填料之體積電阻率。W₁表示相對於前述液晶聚酯100質量份之前述第一碳黑的含量。W₃表示相對於前述液晶聚酯100質量份之前述板狀填料的含量。)

(ρ ₁ represents the volume resistivity of the aforementioned first carbon black. ρ ₃ represents the volume resistivity of the plate-shaped filler. W ₁ represents the content of the aforementioned first carbon black relative to 100 parts by mass of the aforementioned liquid crystal polyester. _{W 3} Indicates the content of the platy filler relative to 100 parts by mass of the liquid crystal polyester.)

[7] The liquid crystal polyester composition as described in [1] or [2], further comprising a filler, and the filler is a fibrous filler or a platy filler.

The content _W2 of the fibrous filler is not less than 10 parts by mass and not more than 130 parts by mass relative to 100 parts by mass of the liquid crystal polyester, and the content _W3 of the platy filler is 5 parts by mass relative to 100 parts by mass of the liquid crystal polyester. More than 80 mass parts or less.

[8] The liquid crystal polyester composition as described in [7], wherein the relationship between the volume resistivity and content of the aforementioned first carbon black and the volume resistivity and content of the aforementioned fibrous filler is expressed by the following formula (S3): When the ratio R ₁₂₃ is expressed, the ratio R ₁₂₃ exceeds 1×10 ⁵ and is less than 1×10 ¹¹ .

(ρ₁表示前述第一碳黑之體積電阻率。ρ₂表示前述纖維狀填料之體積電阻率。ρ₃表示所述板狀填料的體積電阻率。W₁表示相對於100質量份之前述液晶聚酯100質量份之前述第一碳黑的含量。W₂表示相對於前述的液晶聚酯100質量份之前述纖維狀填料的含量。W₃表示相對於前述液晶聚酯100質量份之前述板狀填料的含量。)

(ρ ₁ represents the volume resistivity of the aforementioned first carbon black. ρ ₂ represents the volume resistivity of the aforementioned fibrous filler. ρ ₃ represents the volume resistivity of the plate-shaped filler. _{W 1} represents the aforementioned liquid crystal relative to 100 parts by mass Content of the aforementioned first carbon black in 100 parts by mass of polyester. W ₂ represents the content of the aforementioned fibrous filler relative to 100 parts by mass of the aforementioned liquid crystal polyester. W ₃ represents the aforementioned plate relative to 100 parts by mass of the aforementioned liquid crystal polyester content of fillers.)

[9] The liquid crystal polyester composition as described in [4] or [8], wherein the volume resistivity ρ ₂ of the fibrous filler is 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. below m.

[10] The liquid crystal polyester composition as described in [6] or [8], wherein the volume resistivity ρ ₃ of the platy filler is 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. below m.

[11] The liquid crystal polyester composition as described in [4], [6] or [8], wherein the volume resistivity ρ ₁ of the first carbon black is 1×10 ² Ω. 1×10 ⁷ Ω above m. below m.

[12] The liquid crystal polyester composition according to any one of [1] to [11], wherein the flow initiation temperature of the liquid crystal polyester is not less than 280°C and not more than 420°C.

[13] The liquid crystal polyester composition according to any one of [1] to [12], wherein the liquid crystal polyester contains a structural unit (I) derived from an aromatic hydroxycarboxylic acid, The structural unit (II) derived from alcohol and the structural unit (III) derived from aromatic dicarboxylic acid have a content rate of 30% of the structural unit (I) relative to the total molar amount of all structural units constituting the liquid crystal polyester. Mole% to 80 mole%, relative to the total mole amount of all structural units constituting the liquid crystal polyester, the content of the structural unit (II) is from 10 mole% to 35 mole%, relative to The total molar amount of all structural units constituting the liquid crystalline polyester is such that the content of the structural unit (III) is 10 mol % or more and 35 mol % or less.

[14] The liquid crystal polyester composition according to [13], wherein the aromatic hydroxycarboxylic acid-based p-hydroxybenzoic acid, the aromatic diol-based hydroquinone, and 4,4'-dihydroxybiphenyl at least one of the . The aforementioned aromatic dicarboxylic acid is at least one selected from the group consisting of terephthalic acid and isophthalic acid.

[15] A molded article comprising the liquid crystal polyester composition described in any one of [1] to [14].

[16] is a molded product as described in [15] for the internal parts of the housing in the electrical/electronic machine.

According to one aspect of the present invention, there are provided a molded article capable of suppressing an increase in charge amount, and a liquid crystalline polyester composition capable of producing the molded article in this manner.

<Liquid Crystal Polyester Composition>

The liquid crystal polyester composition of this embodiment contains liquid crystal polyester and carbon black. In addition, the term "carbon black" here refers to carbon black consisting only of the first carbon black described later, or carbon black consisting only of the first carbon black and the second carbon black described later.

In addition, in this specification, the mixture obtained by mixing liquid crystal polyester and at least carbon black is called a "composition." In addition, what molded the obtained mixture into pellets is also called a "composition" similarly.

[liquid crystal polyester]

One of the liquid crystal polyester thermotropic liquid crystal polymers of this embodiment. The liquid crystal polyester of this embodiment is a resin obtained by forming a melt exhibiting optical anisotropy at a temperature of 200°C to 450°C.

Specifically, examples of liquid crystal polyesters include (1) resins obtained by polymerizing aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, and aromatic diols, (2) resins obtained by polymerizing multiple types of aromatic hydroxycarboxylic acids Resin, (3) Resin obtained by polymerizing aromatic dicarboxylic acid and aromatic diol, (4) Resin obtained by reacting crystalline polyester such as polyethylene terephthalate with aromatic hydroxycarboxylic acid wait.

In addition, in the production of liquid crystal polyester, some or all of the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid and aromatic diol used as raw material monomers may be polymerized as ester-forming derivatives in advance. There is an advantage that liquid crystal polyester can be produced more easily by using the ester-forming derivative of this aspect.

As ester-forming derivatives, the following forms can be exemplified: As examples of ester-forming derivatives of aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids having a carboxyl group in the molecule, the above-mentioned carboxyl group is converted into a haloformyl group ( That is, acid halides), acyloxycarbonyl (ie acid anhydride) and other highly reactive groups; the aforementioned carboxyl group is formed by ester exchange reaction with polyols such as monohydric alcohols and ethylene glycol, Phenols, etc. are formed into esters.

As examples of polymerizable derivatives of compounds having phenolic hydroxyl groups such as aromatic hydroxycarboxylic acids and aromatic diols, the aforementioned phenolic hydroxyl groups can be exemplified by transesterification with lower carboxylic acids in such a manner that polyesters are formed by transesterification. Those who form esters.

In addition, the aromatic ring of the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, or aromatic diol may have a halogen atom such as chlorine atom, fluorine atom, methyl group, Alkyl groups with 1 to 10 carbons such as ethyl and butyl; aryl groups with 6 to 20 carbons such as phenyl as substituents.

Examples of the aromatic hydroxycarboxylic acid include p-hydroxybenzoic acid (derived from the aromatic hydroxycarboxylic acid (A ₁ ) described later), m-hydroxybenzoic acid, and 6-hydroxy-2-naphthoic acid (derived from the (A ₂ ) described later. aromatic hydroxycarboxylic acid), 3-hydroxy-2-naphthoic acid, 5-hydroxy-1-naphthoic acid, 4-hydroxy-4'-carboxydiphenyl ether, or the aromatic ring of these aromatic hydroxycarboxylic acids An aromatic hydroxycarboxylic acid formed by substituting a part of the hydrogen atoms with at least one substituent selected from the group consisting of an alkyl group, an aryl group or a halogen atom. The aforementioned aromatic hydroxycarboxylic acids may be used alone or in combination of two or more in the production of liquid crystal polyester.

As a structural unit of the aromatic hydroxycarboxylic acid derived from this aspect, what is shown below is mentioned. In addition, a part of the hydrogen atoms in the aromatic ring of the structural unit derived from an aromatic hydroxycarboxylic acid may be substituted with at least one substituent selected from the group consisting of a halogen atom, an alkyl group, and an aryl group.

In addition, the term "derived from" in this specification means that the chemical structure is changed for the purpose of polymerizing the raw material monomers, and that no other structural changes occur.

Examples of the aromatic dicarboxylic acid include terephthalic acid (an aromatic dicarboxylic acid derived from (B ₁ ) described later), isophthalic acid (an aromatic dicarboxylic acid derived from (B ₂ ) described later), biphenyl -4,4'-dicarboxylic acid, 2,6-naphthalene dicarboxylic acid (aromatic dicarboxylic acid derived from (B ₃ ) described later), diphenyl ether-4,4'-dicarboxylic acid, diphenyl sulfide- 4,4'-dicarboxylic acid, or a part of the hydrogen atoms of the aromatic ring of these aromatic dicarboxylic acids is substituted with at least one substituent selected from the group consisting of alkyl, aryl or halogen atoms Aromatic dicarboxylic acids. The aforementioned aromatic dicarboxylic acids may be used alone or in combination of two or more kinds in the production of liquid crystal polyester.

As a structural unit derived from the aromatic dicarboxylic acid of this aspect, for example, what is shown below is mentioned, for example. In addition, a part of hydrogen atoms in the aromatic ring of the structural unit derived from an aromatic dicarboxylic acid may be substituted with at least one substituent selected from the group consisting of a halogen atom, an alkyl group, and an aryl group.

Examples of the aromatic diol include 4,4'-dihydroxybiphenyl (an aromatic diol derived from (C ₁ ) described later), hydroquinone (an aromatic diol derived from (C ₂ ) described later), Resorcinol (derived from aromatic diols (C ₃ ) described later), 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenyl ether, bis(4-hydroxyphenyl ) methane, 1,2-bis(4-hydroxyphenyl)ethane, 4,4'-dihydroxydiphenylsulfide, 4,4'-dihydroxydiphenylsulfide, 2,6-dihydroxynaphthalene , 1,5-dihydroxynaphthalene, or some hydrogen atoms of the aromatic rings of these aromatic diols are replaced by at least one substituent selected from the group consisting of alkyl, aryl and halogen atoms of aromatic diols. The aforementioned aromatic diols may be used alone or in combination of two or more kinds in the production of liquid crystal polyester.

As a structural unit derived from the aromatic diol of this aspect, for example, what is shown below is mentioned. In addition, in the structural unit derived from an aromatic diol, a part of hydrogen atoms in the aromatic ring may be substituted with at least one substituent selected from the group consisting of a halogen atom, an alkyl group, and an aryl group.

Among the substituents that the aforementioned structural units (structural units derived from aromatic hydroxycarboxylic acids, structural units derived from aromatic dicarboxylic acids, and structural units derived from aromatic diols) may optionally have, examples of halogen atoms , can cite fluorine atom, chlorine atom, bromine atom; As an example of an alkyl group, preferably a lower alkyl group with a carbon number of about 1 to 4, for example, methyl, ethyl and butyl can be cited; as an example of an aryl group can be List phenyl.

Regarding particularly preferable liquid crystal polyesters, the following explanations will be made.

In terms of the structural unit (I) derived from an aromatic hydroxycarboxylic acid, the liquid crystal polyester preferably has a structural unit (A ₁ ) derived from p-hydroxybenzoic acid or one derived from 6-hydroxy-2-naphthoic acid. At least one of the structural units (A ₂ ). The liquid crystal polyester preferably has a structural unit (B 1 ) derived from terephthalic acid, a structural unit (B ₁ ) derived from isophthalic acid, and a structural unit (II) derived from an aromatic dicarboxylic acid. ₂ ) and a structural unit selected from the group of structural units (B ₃ ) derived from 2,6-naphthalene dicarboxylic acid. The liquid crystal polyester preferably has a structural unit (C ₂ ) derived from hydroquinone or a structure derived from 4,4'-dihydroxybiphenyl as the structural unit (III) derived from aromatic diol at least one of the units (C ₁ ).

And, as these combinations, those represented by the following (a) to (h) are preferable.

(a): A combination including (A ₁ ), (B ₁ ) and (C ₁ ), or a combination including (A ₁ ), (B ₁ ), (B ₂ ) and (C ₁ ).

(b): A combination comprising (A ₂ ), (B ₃ ) and (C ₂ ), or a combination comprising (A ₂ ), (B ₁ ), (B ₃ ) and (C ₂ ).

(c): A combination including (A ₁ ) and (A ₂ ).

(d): In the combination of the structural units of (a), a part or all of (A ₁ ) is replaced by (A ₂ ).

(e): In the combination of the structural units of (a), a part or all of (B ₁ ) is replaced by (B ₃ ).

(f): In the combination of the structural units of (a), part or all of (C ₁ ) is replaced by (C ₃ ).

(g): In the combination of structural units of (b), a part or all of (A ₂ ) is replaced by (A ₁ ).

(h): Add (B ₁ ) and (C ₂ ) to the combination of structural units in (c).

The content of the structural unit (I) derived from an aromatic hydroxycarboxylic acid is preferably from 30 mol% to 80 mol% relative to the total molar amount of all structural units constituting the liquid crystal polyester. In addition, the content of the aromatic diol-derived structural unit (II) is preferably from 10 mol % to 35 mol % relative to the total molar amount of all structural units constituting the liquid crystal polyester. In addition, the content of the structural unit (III) derived from the aromatic dicarboxylic acid is preferably from 10 mol % to 35 mol % relative to the total molar amount of all structural units constituting the liquid crystal polyester. As the liquid crystal polyester, resins satisfying all of the above are preferable.

The content of the p-hydroxybenzoic acid-derived structural unit (A1) is preferably from 30 mol% to 80 mol% relative to the total molar amount of all structural units constituting the liquid crystal polyester. In addition, the content rate of at least one of the structural unit (C ₂ ) derived from hydroquinone and the structural unit (C ₁ ) derived from 4,4'-dihydroxybiphenyl, with respect to the total structure constituting the liquid crystal polyester The total molar amount of the unit is preferably not less than 10 mol % and not more than 35 mol %. In addition, the content of at least one selected from the group consisting of terephthalic acid-derived structural units (B ₁ ) and isophthalic acid-derived structural units (B ₂ ) relative to the constituents of the liquid crystal polyester The total molar amount of all structural units is preferably not less than 10 mol% and not more than 35 mol%. As the liquid crystal polyester, resins satisfying all of the above are preferable.

As a method for producing the liquid crystal polyester, for example, a known method such as the method described in JP-A-2002-146003 can be applied. That is, it may be mentioned that the above-mentioned raw material monomers (aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, or derivatives thereof for ester formation) are melt-polymerized (polycondensed) to obtain relatively low-molecular-weight Aromatic polyester (hereinafter abbreviated as "prepolymer"), followed by powdering the prepolymer and performing solid phase polymerization by heating. By carrying out solid-state polymerization in this way, the polymerization is further promoted, and a higher molecular weight liquid crystal polyester can be obtained.

In addition, the production method of liquid crystal polyester having the combination of the structural units of (a) and (b) which is the most basic structure has been described in Japanese Patent Publication No. 47-47870 and Japanese Patent Publication No. 63-3888. Bulletin etc.

Melt polymerization can also be carried out in the presence of a catalyst. As examples of the catalyst in this case, metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide can be enumerated; As nitrogen-containing heterocyclic compounds such as 4-(dimethylamino)pyridine and 1-methylimidazole, nitrogen-containing heterocyclic compounds are preferably used.

As the liquid crystal polyester used in the molded article of this embodiment, liquid crystal polyester having a flow initiation temperature of 280° C. or higher obtained by the method described below is preferable. As described above, when solid phase polymerization is used in the production of liquid crystalline polyester, the flow initiation temperature of the liquid crystalline polyester can be set to 280° C. or higher in a relatively short time. And, by using the liquid crystal polyester having the flow initiation temperature in this way as the thermoplastic resin of this embodiment, the obtained molded article has high heat resistance.

On the other hand, the flow initiation temperature of the liquid crystal polyester used in the molded article of this embodiment is preferably 420°C or lower, more preferably 390°C or lower, for molding the molded article in a practical temperature range.

On the other hand, the flow initiation temperature of the liquid crystal polyester used in the liquid crystal polyester composition of this embodiment is preferably not less than 280°C and not more than 420°C, and more preferably not less than 280°C and not more than 390°C.

Here, as for the flow start temperature, a capillary rheometer equipped with a mold with an inner diameter of 1 mm and a length of 10 mm was used to heat the liquid crystal polymer under a load of 9.8 MPa (100 kg/cm ² ) at a heating rate of 4°C/min. When the ester is extruded from the nozzle, it shows the temperature at which the melt viscosity is 4800 Pa.s (48000 poise). The flow initiation temperature is an index indicating the molecular weight of a liquid crystal polyester known in the art. (See Edited by Naoyuki Koide, "Synthesis, Forming, and Application of Liquid Crystalline Polymers-", pages 95-105, CMC, published on June 5, 1987). As a device for measuring the flow start temperature, for example, a flow characteristic evaluation device "Flow Tester CFT-500D" manufactured by Shimadzu Corporation can be used.

The liquid crystal polyester of this form is excellent in heat resistance and fluidity at the time of melting. Therefore, it is preferably used as a forming material of molded articles described later.

Liquid crystal polyesters may be used alone or in combination of two or more.

On the other hand, the content of the liquid crystal polyester in the liquid crystal polyester composition of this embodiment is preferably 30 to 90% by mass relative to the total mass of the liquid crystal polyester composition.

[carbon black]

The carbon black in the liquid crystal polyester composition of this embodiment has the effect of imparting conductivity to the liquid crystal polyester.

(first carbon black)

The carbon black used in the liquid crystal polyester composition of this embodiment contains the first carbon black that satisfies the following conditions (A) and (B).

On the other hand, the carbon black of the liquid crystal polyester composition of this embodiment only contains the first carbon black that satisfies the following conditions (A) and (B).

On the other hand, the carbon black of the liquid crystal polyester composition of the present embodiment includes only the first carbon black satisfying the following condition (A) and condition (B) and the second carbon black described later.

(A): The primary particle diameter is not less than 10 nm and not more than 50 nm.

(B): The DBP oil absorption is not less than 300 cm ³ /100 g and not more than 550 cm ³ /100 g.

In the present embodiment, the primary particle size of carbon black is a value measured by a transmission electron microscope.

In the present embodiment, the DBP oil absorption of carbon black is a value measured via dibutyl phthalate using an absorbance meter according to JIS K6221.

When the primary particle diameter of the first carbon black is 10 nm or more, the surface resistance value of the molded article molded from the liquid crystal polyester composition can be sufficiently reduced. As a result, an increase in the charge amount of the molded article can be suppressed.

When the primary particle diameter of the first carbon black is 50 nm or less, it is easy to disperse the first carbon black in the liquid crystal polyester when producing a liquid crystal polyester composition or molded article. In the molded article thus obtained, it is easy to make the surface resistance value of the inner surface of the molded article uniform. As a result, an increase in the amount of charge can be suppressed at any position on the inner surface of the molded product.

The primary particle diameter of the first carbon black is preferably not less than 20 nm and not more than 45 nm, and more preferably not less than 30 nm and not more than 40 nm.

A higher DBP oil absorption of the first carbon black means more voids near the surface of the first carbon black. When there are many voids in the vicinity of the surface of the first carbon black, the first carbon blacks in the liquid crystalline polyester are easily drawn to each other and are easily connected.

When the DBP oil absorption of the first carbon black is 300 cm ³ /100 g or more, the molded article molded from the liquid crystalline polyester composition can easily and sufficiently conduct electricity to the connecting portion of the first carbon black. As a result, the surface resistance value of the molded product can be sufficiently reduced. Therefore, an increase in the charge amount in the molded article can be sufficiently suppressed.

However, when the DBP oil absorption of the first carbon black is too high, there are too many voids near the surface of the first carbon black, and the first carbon blacks in the liquid crystal polyester are likely to strongly pull each other. When liquid crystal polyester, carbon black, and additives added as needed are melt-kneaded, the viscosity of the mixture becomes high. As a result, it is difficult to granulate the mixture, and it is difficult to produce a liquid crystal polyester composition.

The DBP oil absorption of the first carbon black is less than 550cm ³ /100g, and when the liquid crystal polyester, carbon black, and additives added according to requirements are melt-kneaded, the viscosity of the mixture will not become too high. As a result, the mixture becomes easy to granulate, and a liquid crystal polyester composition can be easily produced.

The DBP oil absorption of the first carbon black is preferably from 325 cm ³ /100 g to 550 cm ³ /100 g, more preferably from 350 cm ³ /100 g to 525 cm ³ /100 g.

The BET specific surface area of the first carbon black is preferably from 500 m ² /g to 1500 m ² /g, more preferably from 700 m ² /g to 1350 m ² /g, more preferably from 750 m ² /g to 1300 m ² /g.

In this embodiment, the BET specific surface area of carbon black is measured using a BET specific surface area measuring device (for example, AccuSorb 2100E manufactured by McMeritick Instruments Co., Ltd.) to make it adsorb nitrogen at the temperature of liquid nitrogen, and measure its adsorption. amount, and use the value calculated by the BET method.

Generally, the BET specific surface area of a particle is affected by the particle size. However, in the first carbon black of this embodiment, the amount of voids formed in the first carbon black is more dominant. Therefore, it means that the larger the BET specific surface area of the first carbon black, the larger the amount of voids formed in the first carbon black.

As described above, when the amount of voids formed in the first carbon black is large, the first carbon blacks in the liquid crystal polyester are easily connected to each other.

When the BET specific surface area of the first carbon black is 500 m ² /g or more, the molded article formed of the liquid crystalline polyester composition can easily and sufficiently conduct electricity at the connecting portion of the first carbon black. As a result, the surface resistance value of the molded product can be sufficiently reduced. Therefore, an increase in the charge amount of the molded article can be sufficiently suppressed.

However, when the BET specific surface area of the first carbon black is too high, it can be said that the amount of voids formed in the first carbon black is too large. As described above, when the amount of voids formed by the first carbon black is too large, the viscosity of the mixture becomes high when the liquid crystal polyester, carbon black, and optionally added additives are melt-kneaded. As a result, it becomes difficult to granulate the mixture, and it becomes difficult to manufacture a liquid crystal polyester composition.

When the BET specific surface area of the first carbon black is 1500 m ² /g or less, when the liquid crystal polyester composition or molded article is produced, when the liquid crystal polyester, carbon black, and additives added as required are melt-kneaded, the mixture of these The viscosity will not become too high.

As a result, the mixture becomes easy to granulate, and the liquid crystal polyester composition becomes easy to manufacture.

The volume resistivity ρ ₁ of the first carbon black is preferably 1×10 ² Ω. 1×10 ⁷ Ω above m. m or less, preferably 1×10 ³ Ω. 1×10 ⁶ Ω above m. below m.

When the volume resistivity _ρ1 of the first carbon black is within the above-mentioned range, the surface resistance value of the molded article molded from the liquid crystalline polyester composition can be sufficiently reduced. Therefore, an increase in the charge amount of the molded article can be suppressed.

In this embodiment, the volume resistivity of the first carbon black is measured with an insulation resistance tester R8340A at a temperature of 23°C and a humidity of 50% after the first carbon black has been left to stand in a silica gel drier for 24 hours. Value measured by an ultra-high resistance meter (manufactured by ADC Co., Ltd.).

(second carbon black)

The carbon black related to the liquid crystal polyester composition of this embodiment may contain the second carbon black within the range that does not impair the effect of the present invention. The second carbon black does not satisfy at least one of the condition (A) and the condition (B).

(A): The primary particle diameter is not less than 10 nm and not more than 50 nm.

(B): The DBP oil absorption is not less than 300 cm ³ /100 g and not more than 550 cm ³ /100 g.

Although the second carbon black is not as effective as the first carbon black described above, the second carbon black has the effect of imparting conductivity to the liquid crystal polyester. In addition, compared with the above-mentioned first carbon black, the second carbon black can suppress the viscosity increase of the liquid crystal polyester mixture when it is blended with the liquid crystal polyester. Therefore, in this embodiment, by using the first carbon black and the second carbon black in combination, the liquid crystal polyester composition can be provided that can suppress the increase in the viscosity of the liquid crystal polyester mixture and can suppress the increase in the charge amount when used as a molded product. .

[Carbon black content]

In the liquid crystal polyester composition of the present embodiment, the content _W1 of the first carbon black is not less than 1 part by mass and not more than 10 parts by mass relative to 100 parts by mass of the liquid crystal polyester.

When the content W ₁ of the first carbon black is 1 part by mass or more, the surface resistance value of the molded article molded from the liquid crystalline polyester composition can be sufficiently reduced. As a result, an increase in the charge amount in the molded article can be suppressed.

Compared with the second carbon black, when the liquid crystal polyester, carbon black, and additives added as needed are melt-kneaded, the viscosity of the mixture of the first carbon black tends to become higher.

If the content W ₁ of the first carbon black is 10 parts by mass or less, the viscosity of the above mixture will not become too high. As a result, the mixture becomes easy to granulate, and it becomes easy to produce a liquid crystal polyester composition.

In addition, when the content W ₁ of the first carbon black is 10 parts by mass or less, the absolute value of the charge amount does not become excessively lowered. Therefore, by making content _W1 of the 1st carbon black into the range of 1 mass part or more and 10 mass parts or less, the absolute value of charge amount can be controlled.

In the liquid crystal polyester composition of this embodiment, the content _W1 of the first carbon black is preferably not less than 2 parts by mass and not more than 9 parts by mass relative to 100 parts by mass of the liquid crystal polyester.

As mentioned above, the carbon black in the liquid crystal polyester composition of this embodiment may further contain the second carbon black within the range that does not impair the effect of the present invention. In the liquid crystal polyester composition of the present embodiment, the content of the second carbon black is not less than 0 parts by mass and not more than 9 parts by mass relative to 100 parts by mass of the liquid crystal polyester. On the other hand, the content of the second carbon black may be not less than 0 parts by mass and not more than 3 parts by mass, or may be not less than 2 parts by mass and not more than 3 parts by mass with respect to 100 parts by mass of the liquid crystal polyester.

In the liquid crystal polyester composition of this embodiment, the total content of the first carbon black and the second carbon black (hereinafter, sometimes referred to as the content of carbon black) is 1 mass part with respect to 100 parts by mass of the liquid crystal polyester. More than 10 parts by mass.

When the content of the carbon black is 1 part by mass or more, the content of the first carbon black in the carbon black can be sufficiently increased. As a result, the surface resistance value of the molded article molded from the liquid crystalline polyester composition can be sufficiently reduced. Therefore, an increase in the charge amount of the molded article can be suppressed.

When the content of the aforementioned carbon black is 10 parts by mass or less, the first carbon black and the second carbon black added as necessary in the liquid crystal polyester are easily dispersed in the liquid crystal polyester composition or molded article. In this way, in the obtained molded product, the surface resistance value of the inner surface of the molded product tends to be uniform. As a result, an increase in the amount of charge can be suppressed even at any position on the inner surface of the molded product.

In addition, when the content of the aforementioned carbon black is 10 parts by mass or less, the absolute value of the charge amount does not decrease excessively. Therefore, by setting the content of the carbon black within the range of 1 part by mass to 10 parts by mass, the absolute value of the charge amount can be controlled.

In the liquid crystal polyester composition of this embodiment, the content of the carbon black is preferably not less than 3 parts by mass and not more than 9 parts by mass relative to 100 parts by mass of the liquid crystal polyester.

[Filler]

The liquid crystal polyester composition of this embodiment preferably further contains a filler in addition to the liquid crystal polyester and the first carbon black. Thereby, the strength and dimensional stability of the molded article molded from the liquid crystal polyester composition are improved upward.

On the one hand, the liquid crystal polyester composition of this embodiment contains liquid crystal polyester, first carbon black and filler.

On the other hand, the liquid crystal polyester composition of this embodiment contains liquid crystal polyester, first carbon black, second carbon black and filler.

The filler in the liquid crystal polyester composition of this embodiment is a fibrous filler or a platy filler. In addition, the liquid crystal polyester composition of this embodiment preferably contains both fibrous fillers and platy fillers.

(fibrous filler)

Examples of the fibrous filler include glass fibers; ceramic fibers such as silica fibers, alumina fibers, and silica-alumina fibers; and metal fibers such as stainless steel fibers. In addition, whiskers such as potassium titanate whiskers, barium titanate whiskers, wollastonite whiskers, aluminum borate whiskers, silicon nitride whiskers, and silicon nitride whiskers are also exemplified.

On the one hand, the number average fiber length of the fibrous filler is preferably 30 μm to 3 mm, and the number average fiber diameter is preferably 6 to 13 μm.

In the liquid crystal polyester composition of this embodiment, the content _W2 of the fibrous filler is preferably at least 10 parts by mass and not more than 130 parts by mass, more preferably at least 10 parts by mass and not less than 80 parts by mass, relative to 100 parts by mass of the liquid crystal polyester. It is not more than 10 parts by mass, more preferably not less than 10 parts by mass and not more than 50 parts by mass, particularly preferably not less than 10 parts by mass and not more than 45 parts by mass. On the other hand, content _W2 of a fibrous filler may be 23 mass parts or more and 45 mass parts or less.

When the content _W2 of the fibrous filler is 10 parts by mass or more, the strength of the molded article after molding the liquid crystalline polyester composition becomes sufficiently high.

When the content _W2 of the fibrous filler is 130 parts by mass or less, when the liquid crystal polyester, carbon black, and fibrous filler are melt-kneaded, the viscosity of the mixture does not become too high. As a result, the first carbon black in the liquid crystal polyester is easily dispersed.

As described above, in the molded article molded from the liquid crystal polyester composition in which the first carbon black is sufficiently dispersed, the surface resistance value of the inner surface of the molded article tends to be uniform. As a result, an increase in the amount of charge can be suppressed even at any position on the inner surface of the molded product.

(plate packing)

Examples of platy fillers include talc, mica, graphite, wollastonite, barium sulfate, and calcium carbonate. Among them, the mica may also be muscovite, phlogopite, fluorophlogopite or tetrasilica.

In the liquid crystal polyester composition of this embodiment, the content _W3 of the platy filler is preferably not less than 5 parts by mass and not more than 80 parts by mass, more preferably not less than 5 parts by mass and not more than 50 parts by mass, relative to 100 parts by mass of the liquid crystal polyester. It is less than 5 parts by mass, more preferably not less than 5 parts by mass and not more than 30 parts by mass, particularly preferably not less than 10 parts by mass and not more than 25 parts by mass. On the other hand, the content W ₃ of the platy filler may be not less than 17 parts by mass and not more than 23 parts by mass.

When the content _W3 of the platy filler is 5 parts by mass or more, the dimensional stability and strength of the molded article molded from the liquid crystalline polyester composition become sufficiently high.

When the content W ₃ of the platy filler is 80 parts by mass or less, when the liquid crystal polyester, carbon black, and platy filler are melt-kneaded, the viscosity of the mixture does not become too high. As a result, the first carbon black in the liquid crystal polyester is easily dispersed.

As described above, in the molded article molded from the liquid crystal polyester composition in which the first carbon black is sufficiently dispersed, the surface resistance value of the inner surface of the molded article tends to be uniform. As a result, an increase in the amount of charge can be suppressed even at any position on the inner surface of the molded product.

[Volume resistivity of filler]

The volume resistivity ρ ₂ of the fibrous filler is preferably 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. m or less, more preferably 1×10 ¹⁰ Ω. 1×10 ¹³ Ω above m. below m.

When the volume resistivity _ρ2 of the fibrous filler is within the above-mentioned range, the surface resistance value of the molded article molded from the liquid crystal polyester composition can be sufficiently reduced. Therefore, an increase in the charge amount of the molded article can be suppressed.

The volume resistivity ρ ₃ of the platy filler is preferably 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. m or less, more preferably 1×10 ¹⁰ Ω. 1×10 ¹³ Ω above m. below m.

When the volume resistivity _ρ3 of the platy filler is within the above range, the surface resistance value of the molded article molded from the liquid crystalline polyester composition can be sufficiently reduced. Therefore, an increase in the charge amount of the molded article can be suppressed.

In addition, the method of measuring the volume resistivity of the fibrous filler and the platy filler is the same as the method of measuring the volume resistivity of the first carbon black.

When the liquid crystal polyester composition of this embodiment contains only fibrous fillers as fillers, the ratio R ₁₂ represented by the following formula (S1) is preferably more than 1×10 ⁵ and less than 1×10 ¹¹ , and then It is preferably from 1×10 ⁶ to 1×10 ¹⁰ , more preferably from 1×10 ⁷ to 1×10 ⁹ .

As described above, _ρ1 represents the volume resistivity of the first carbon black. _ρ2 represents the volume resistivity of the fibrous filler. W ₁ represents the content (parts by mass) of the first carbon black with respect to 100 parts by mass of the liquid crystal polyester. W ₂ represents the content (parts by mass) of the fibrous filler relative to 100 parts by mass of the liquid crystal polyester.

When the liquid crystal polyester composition of this embodiment contains only a platy filler as a filler, the ratio R ₁₃ represented by the following formula (S2) is preferably more than 1×10 ⁵ and less than 1×10 ¹¹ , and then It is preferably from 1×10 ⁵ to 1×10 ⁹ , more preferably from 5×10 ⁵ to 1×10 ⁸ .

As mentioned above, _ρ3 represents the volume resistivity of the platy filler. W ₃ represents the content (parts by mass) of the platy filler relative to 100 parts by mass of the liquid crystal polyester.

When the liquid crystal polyester composition of this embodiment contains fibrous fillers and platy fillers as fillers, the ratio R ₁₂₃ represented by the following formula (S3) is preferably more than 1×10 ⁵ and less than 1×10 ¹¹ , more preferably from 1×10 ⁶ to 1×10 ¹⁰ , more preferably from 1.1×10 ⁷ to 1×10 ⁹ .

In this embodiment, in order to control the absolute value of the charge amount of the molded product, it is important not only to specify the volume resistivity but also the content of all components that can affect the charge amount. The ratios R ₁₂ , R ₁₃ and R ₁₂₃ specified in this embodiment represent the volume resistivity (ρ ₁ , ρ ₂ and ρ ₃ ) and content (W ₁ , W ₂ and W ₃ ) parameters of both. When the ratios R ₁₂ , R ₁₃ , and R ₁₂₃ satisfy desired ranges, the balance between volume resistivity and content can be regulated, and the absolute value of charge amount can be regulated.

[other ingredients]

The liquid crystal polyester composition of this embodiment may further contain components other than the above-mentioned fillers within the range that does not impair the effects of the present invention.

Examples of the above-mentioned components include mold release modifiers such as fluororesins and metal soaps; colorants such as dyes and pigments; antioxidants; heat stabilizers; ultraviolet absorbers; antistatic agents; Additives for forming materials of products.

In addition, examples of the above-mentioned components include components having an external lubricating effect such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, and fluorocarbon-based surfactants.

In addition, thermosetting resins such as phenolic resins, epoxy resins, and polyimide resins are mentioned as examples of the above-mentioned components.

If a liquid crystal polyester composition having the above-mentioned composition is used, a molded product in which the absolute value of the charge amount can be controlled can be obtained.

On the other hand, relative to the total mass of the liquid crystal polyester composition, the content of the above components is preferably 0 to 10% by mass.

<Molded product>

The molded article of this embodiment contains the above-mentioned liquid crystal polyester composition as a forming material.

The molded product of this embodiment is a molded product used for housing internal parts of electric and electronic equipment. Examples of electrical and electronic equipment include cameras, personal computers, mobile phones, smartphones, tablet computers, printers, projectors, and the like. As the housing internal parts of such electric and electronic equipment, fixing parts for connectors, camera modules, fans, printers, and the like can be cited.

The thickness of the molded product of this embodiment is at least 0.1 mm, preferably at least 0.2 mm, further preferably at least 0.5 mm, and more preferably at least 1 mm. In addition, the thickness of the molded product is preferably 20 mm or less.

On the other hand, the thickness of the molded product of this embodiment is 0.1 mm to 20 mm, preferably 0.2 mm to 20 mm, more preferably 0.5 mm to 20 mm, more preferably 1 mm to 20 mm.

The thickness of the molded product in this specification means the thickness (shortest distance) from one side of the molded product to the other side.

When the molded product has uneven thickness such as a fan machine, the thickness of the thinnest part may be 0.1 mm, preferably 0.2 mm or more, further preferably 0.5 mm or more, more preferably 1 mm or more. In addition, the thickness of the thickest portion is preferably 20 mm or less. The thickness of the molded product is the average value of the measured values when the thickness of the molded product is randomly measured at three positions using a micrometer or a non-contact three-dimensional measuring device (QuickVisionPRO, trade name, manufactured by Mitutoyo Instruments Co., Ltd.). In addition, when any one of the micrometer and the above-mentioned non-contact three-dimensional measuring device is selected, the thickness of the molded product can also be quantitatively obtained.

Hereinafter, the case of a fixed part for a printer will be taken as an example to explain the internal parts of a housing of an electric/electronic machine, but the present embodiment is not limited thereto.

Usually, the surface of the fixed parts used in the printer is flat, so that the copy paper can be fed smoothly and smoothly. However, static electricity is generated when the above-mentioned fixing parts rub against copy paper. Due to static electricity between the transfer step and the fixing step in the image forming process, the toner adheres to the copy paper, so when the charge amount of the above-mentioned fixing portion increases, the position of the transferred electrostatic image may be deviated. shift.

In addition, as a result of intensive research by the present inventors, it was found that if the absolute value of the charge amount of the internal parts of the housing is too low between the exposure process and the fixing process, even the static electricity required for image formation on copy paper is removed, making the transfer electrostatic image becomes blurred.

Then, in the subsequent fixing process, the electrostatic image is fixed in a shifted state, which may eventually disturb the resulting image.

In the fixed part of the molded product of this embodiment, the surface resistance value of the surface of the contact side with the copy paper on which the toner is attached is 10 ¹² Ω or less and less than 10 ¹⁵ Ω, preferably 10 ¹³ Ω or more 10 ¹⁵ Ω is not reached. When the surface resistance value of the fixing part is 10 ¹² Ω or more, the charge amount after the molded article contacts the copy paper does not become too low, and problems such as peeling of toner adhering to the copy paper hardly occur. On the other hand, when the surface resistance value of the fixing part is less than 10 ¹⁵ Ω, the charge amount after the contact between the molded article and the copy paper does not become too high, and the toner adhered to the copy paper hardly occurs. issues such as stripping.

In addition, the surface resistance value of a molded product is the value measured using the known measuring apparatus based on "ASTM D257". The surface resistance value of the molded product can be determined according to the resistance measurement conditions based on "ASTM D257" (using a digital super insulation/microammeter "DSM-8104", manufactured by DKK-Toa Co., Ltd., at a measurement temperature of 23°C), for example. Determination.

<Manufacturing method of molded product>

As a method of manufacturing the molded article of this embodiment, melt molding is preferred, and examples thereof include extrusion molding, compression molding, blow molding, injection molding, T-shape molding, and inflation. Vacuum forming and compression forming. Among them, the injection molding method is preferable. Hereinafter, as one example of the manufacturing method of the molded article of this embodiment, the case of using the injection molding method will be described.

The injection molding method in this embodiment can use an injection molding machine (for example, manufactured by Nissei Plastic Industry Co., Ltd., "hydraulic horizontal molding machine PS40E5ASE type") to melt the liquid crystal polyester composition, and the molten liquid crystal polyester composition The material is heated to an appropriate temperature and injected into the mold.

The temperature at which the liquid crystal polyester composition is heated and melted for injection is set based on the flow initiation temperature Tp°C of the liquid crystal polyester composition, among which, it is preferably [Tp+10]°C or higher and [Tp+50] below ℃.

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

If a molded article having the above-mentioned composition is used, the absolute value of the charge amount can be controlled.

Therefore, for example, when the molded product is used as a stationary part of a printer, displacement of the position of the transferred electrostatic image can be suppressed, and image noise caused thereby can be suppressed.

In addition, for example, when the molded product is a camera module, it is possible to suppress the adhesion of dust in the air due to static electricity to the camera module, and it is possible to reduce the occurrence of defects due to dust.

In terms of one aspect of the present invention, one embodiment of the liquid crystal polyester composition contains liquid crystal polyester, first carbon black, and second carbon black according to requirements, and a filler; the aforementioned liquid crystal polyester, Contains only structural units derived from p-hydroxybenzoic acid (30 mol% to 80 mol% relative to the total molar amount of all structural units constituting liquid crystal polyester), derived from 4,4'-dihydroxy Structural units of biphenyl (10 mol% to 35 mol% relative to the total molar amount of all structural units constituting liquid crystalline polyester), structural units derived from terephthalic acid (relative to the total molar amount constituting liquid crystalline polyester The total molar amount of the total structural units of the liquid crystal polyester is 10 mol% to 35 mol%), and the structural unit derived from isophthalic acid (relative to the total molar amount of the total structural units constituting the liquid crystal polyester is 10 mol% to 35 mol%) liquid crystal polyester; the aforementioned first carbon black has a primary particle diameter of 30 nm to 40 nm, and the DBP oil absorption is 350 cm ³ /100 g to 525 cm ³ /100 g; the aforementioned The second carbon black is that the DBP oil absorption does not satisfy the condition of 300cm ³ /100g or more and 550cm ³ /100g or less.

The aforementioned filler is a fibrous filler (preferably glass fiber) and a platy filler (preferably talc); relative to the total mass of the aforementioned liquid crystal polyester composition, the content of the aforementioned liquid crystal polyester is 30 to 90% by mass; The content _W1 of the first carbon black is not less than 2 parts by mass and not more than 9 parts by mass with respect to 100 parts by mass of the liquid crystal polyester, and the content W1 of the second carbon black is 0 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. The above is not more than 3 parts by mass, and the total content of the first carbon black and the second carbon black is not less than 3 parts by mass and not more than 9 parts by mass with respect to 100 parts by mass of the aforementioned liquid crystal polyester; with respect to 100 parts by mass of the aforementioned liquid crystal polyester, the aforementioned The content _W2 of the fibrous filler is not less than 23 parts by mass and not more than 45 parts by mass; the content _W3 of the platy filler is not less than 17 parts by mass and not more than 23 parts by mass relative to 100 parts by mass of the liquid crystal polyester; the first carbon black The relationship between the volume resistivity ρ ₁ and content W ₁ of the aforementioned fibrous filler, the volume resistivity ρ ₂ and the content W ₂ of the aforementioned fibrous filler, and the volume resistivity ρ ₃ and the content W ₃ of the aforementioned platy filler are given by the formula ( When represented by the ratio R ₁₂₃ described in S3), the ratio R ₁₂₃ exceeds 4×10 ⁷ and is less than 5.8×10 ⁸ .

In addition, the liquid crystal polyester may have a BET specific surface area of the first carbon black of not less than 750 m ² /g and not more than 1300 m ² /g.

The volume resistivity ρ ₁ of the aforementioned first carbon black may be 1×10 ² Ω. 1×10 ⁷ Ω above m. m or less, the volume resistivity ρ ₂ of the aforementioned fibrous filler can be 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. m or less, the volume resistivity ρ ₃ of the aforementioned platy filler can be 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. below m.

According to another aspect of the present invention, a method for controlling the charge amount of internal parts of a casing, the aforementioned method includes: manufacturing the internal parts of the casing from a liquid crystal polyester composition, and providing the internal parts of the casing on the casing In the body; the aforementioned liquid crystal polyester composition system contains: liquid crystal polyester, and the first carbon black, and the second carbon black according to demand; the aforementioned first carbon black is a carbon that satisfies the following conditions (A) and conditions (B) Black, the aforementioned second carbon black is carbon black that does not satisfy at least one of condition (A) and condition (B), relative to 100 mass parts of the aforementioned liquid crystal polyester, the content W of the aforementioned first carbon black is ₁ mass Parts to 10 parts by mass, with respect to 100 parts by mass of the liquid crystal polyester, the content of the second carbon black is from 0 parts by mass to 9 parts by mass, and, with respect to 100 parts by mass of the liquid crystal polyester, the content of the first carbon black is The total content of black and the aforementioned second carbon black is not less than 1 part by mass and not more than 10 parts by mass.

(A): The primary particle diameter is not less than 10 nm and not more than 50 nm.

(B): The DBP oil absorption is not less than 300 cm ³ /100 g and not more than 550 cm ³ /100 g.

[Example]]

Hereinafter, the present invention will be illustrated by examples, but the present invention is not limited to these examples. In addition, in this example, although the fixed part for printers was assumed as the use of a molded product, evaluation was performed, but the use of a molded product is not limited to this.

Each molded article was evaluated by the following method.

<Measurement of Surface Resistance>

The surface resistance value of molded products. Using resistance measurement conditions based on "ASTM D257" (using a digital super insulation/microammeter "DSM-8104", manufactured by DKK Toa Co., Ltd.), the measurement was performed at a measurement temperature of 23°C.

<Determination of the absolute value of charge>

The test pieces (molded articles) of Examples and Comparative Examples were stacked on fixed copy paper, and the test pieces were reciprocated in one direction under the following conditions to perform a test. The absolute value of the charge amount of the test piece and copy paper after the test was measured using a digital low potential measuring instrument "KSD-300" manufactured by Kasuga Electric Co., Ltd.

[condition]

Device: Surface property measuring machine "HEIDON-14DR" (manufactured by Shinto Scientific Co., Ltd.)

Weight: 5 grams

Reciprocating distance: 60mm

Moving speed: 4000mm/min

Reciprocating times: 50 times

Evaluation environment: temperature 23°C, humidity 50%

<Measurement of Volume Resistivity>

The volume resistivity of the first carbon black, fibrous filler, talc-like filler, etc., is measured at a measurement temperature of 23°C after placing the first carbon black, fibrous filler, and talc-like filler in a silica gel desiccator for 24 hours. Humidity (relative humidity) 50% humidity was measured using an insulation resistance tester R8340A ultra-high resistance meter (manufactured by ADC Co., Ltd.).

<Manufacture Example 1 (Manufacture of Liquid Crystal Polyester (1))>

In a reactor equipped with a stirrer, torque meter, nitrogen inlet tube, thermometer and reflux condenser, put 994.5 g (7.2 moles) of p-hydroxybenzoic acid, 446.9 g (2.4 moles) of 4,4'-dihydroxybiphenyl mol), terephthalic acid 299.0g (1.8 mol), isophthalic acid 99.7g (0.6 mol), acetic anhydride 1347.6g (13.2 mol), etc., then replace the gas in the reactor with nitrogen, and then 0.18 g of 1-methylimidazole was added, the temperature was raised from room temperature (23° C.) to 150° C. over 30 minutes while stirring in a nitrogen stream, and the mixture was refluxed at 150° C. for 30 minutes.

Then, 2.4 g of 1-methylimidazole was added, and the temperature was raised from 150° C. to 320° C. in 2 hours and 50 minutes, while distilling out acetic acid and unreacted acetic anhydride as by-products. When the torque was observed to rise, the The prepolymer was obtained as a solid after the contents were removed from the reactor and cooled to room temperature.

Next, the prepolymer was pulverized using a pulverizer, and the obtained pulverized product was placed in a nitrogen atmosphere, heated from room temperature to 250° C. within 1 hour, and heated from 250° C. to 295° C. over the next 5 hours, and then Solid phase polymerization was carried out by maintaining 295° C. for 3 hours. The obtained solid-phase polymer was cooled to room temperature to obtain a powdery liquid crystal polyester (1). The flow initiation temperature of the obtained liquid crystal polyester (1) was 327°C.

<Manufacture Example 2 (Manufacture of Liquid Crystal Polyester (2))>

In a reactor equipped with a stirrer, torque meter, nitrogen inlet tube, thermometer and reflux condenser, put 994.5 g (7.2 moles) of p-hydroxybenzoic acid, 446.9 g (2.4 moles) of 4,4'-dihydroxybiphenyl mol), terephthalic acid 239.2g (1.44 mol), isophthalic acid 159.5g (0.96 mol), acetic anhydride 1347.6g (13.2 mol), etc., then replace the gas in the reactor with nitrogen, and then 0.18 g of 1-methylimidazole was added, the temperature was raised from room temperature (23° C.) to 150° C. over 30 minutes while stirring in a nitrogen stream, and the mixture was refluxed at 150° C. for 30 minutes.

Next, 2.4 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 acetic acid and unreacted acetic anhydride as a by-product. When a torque rise was observed, the contents were removed from the reactor and cooled to room temperature to yield a solid prepolymer.

Next, the prepolymer was pulverized using a pulverizer, and the obtained pulverized product was placed in a nitrogen atmosphere, heated from room temperature to 220° C. within 1 hour, and heated from 220° C. to 240° C. over the next 30 minutes, and then Solid phase polymerization was performed by maintaining at 240° C. for 10 hours. The obtained solid-phase polymer was cooled to room temperature to obtain a powdery liquid crystal polyester (2). The flow initiation temperature of the obtained liquid crystal polyester (2) was 286°C.

In addition, the following materials were used as carbon black and filler. Physical properties of carbon black and fillers are specified by the manufacturer.

[carbon black]

First carbon black: KETJENBLACK EC300J (manufactured by Lion Specialty Chemicals Co., primary particle size 39.5 nm, DBP oil absorption 360 cm ³ /100 g, BET specific surface area 800 m ² /g, volume resistivity 2.51×10 ⁴ Ω·m).

Second carbon black: CB # 960

(manufactured by Mitsubishi Chemical Corporation, primary particle size 16nm, DBP oil absorption 69cm ³ /100g, BET specific surface area 260m ² /g, volume resistivity 4.96×10 ⁵ Ω·m).

[fibrous filler]

Glass fiber (1): CS3J260S (manufactured by Nitto Bosho Co., Ltd., number average fiber length 3 mm, number average fiber diameter 11 μm, volume resistivity 5.14×10 ¹¹ Ω·m).

Glass fiber (2): EFH 75-01 (manufactured by Central Glass Co., Ltd., number average fiber length 30 μm, number average fiber diameter 11 μm, volume resistivity 3.43×10 ¹¹ Ω·m).

[Plate packing]

Talc: X-50 (manufactured by Japan Talc Co., Ltd., permeability 3.92×10 ¹⁰ Ω·m).

The ratio R ₁₂₃ of the used filler represented by the following formula (S3) is listed in Table 1 and Table 2 in detail.

<Examples 1 to 6, Comparative Examples 1 to 4>

Using a twin-screw extruder ("PCM-30", manufactured by Ikegai Iron Works Co., Ltd.), melt liquid crystal polyester, carbon black, and optionally add ingredients. The mixture was kneaded to obtain a granular liquid crystal polyester composition. In addition, the unit of the ratio shown in Table 1 and Table 2 is a mass part.

The liquid crystal polyester composition was molded at a molding temperature of 350°C, a mold temperature of 130°C, and an injection speed of 100 mm/sec by using an injection molding machine ("PNX40-5A", manufactured by Nissei Plastic Industries Co., Ltd.). Then, a flat test piece having a thickness of 1 mm was formed.

The comprehensive evaluation of embodiment and comparative example is shown in table 3 and table 4. The comprehensive evaluation of Examples and Comparative Examples was performed according to the following criteria using the absolute value of the granulation property and the charge amount of the test piece and the copy paper after the test. Also, in Table 3 and Table 4, the case where the liquid crystal polyester composition can be granulated is evaluated as "A", and the case where the granulation is not possible is evaluated as "B".

A: The granulation is "A", and the absolute value of the charge amount of the test piece is not less than 30V and not more than 200V, and the absolute value of the charge amount of the copy paper is not less than 0V and not more than 5V.

B: Other.

As shown in Table 3 and Table 4, the test pieces of Examples 1 to 6 applicable to the present invention have lower surface resistance. Also, in Examples 1 to 6 to which the present invention is applied, compared with Comparative Examples 1 and 2 to which the present invention is not applied, the absolute values of the charge amounts of both the test piece and the copy paper after the test are smaller.

On the other hand, the test piece of Example 1 to Example 6 to which the present invention was applied had a surface resistance value compared with the test piece of Comparative Example 3. In addition, in Examples 1 to 6 to which the present invention was applied, compared with Comparative Example 3, the absolute value of the charge amount of the test piece after the test was larger.

It can be seen that in the present invention, the surface resistance value of the test piece can be adjusted to 10 ¹² Ω or more by setting the content of the first carbon black and the total content of the first carbon black and the second carbon black as a specific range. In the range of 10 ¹⁵ Ω, the charge increase of both the test piece and the copy paper after the test can be moderately suppressed.

From the above results, it can be confirmed that the present invention has its utility.

[industrial availability]

The present invention is industrially very useful because it is possible to provide a molded article capable of suppressing an increase in charge amount and a liquid crystalline polyester composition capable of obtaining such a molded article.

Claims (13)

A liquid crystal polyester composition, containing liquid crystal polyester, a first carbon black, a second carbon black according to requirements, and a filler, the first carbon black is a carbon black that satisfies the following conditions (A) and (B) , the aforementioned second carbon black is carbon black that does not satisfy at least one of the aforementioned condition (A) and the aforementioned condition (B), relative to 100 mass parts of the aforementioned liquid crystal polyester, the content W of the aforementioned first carbon black is ₁ mass more than 10 parts by mass; relative to 100 parts by mass of the aforementioned liquid crystal polyester, the content of the aforementioned second carbon black is not less than 0 parts by mass and less than 9 parts by mass; relative to 100 parts by mass of the aforementioned liquid crystal polyester, the content of the aforementioned first carbon black and The total content of the second carbon black is not less than 1 part by mass and not more than 10 parts by mass. The filler is a fibrous filler and a platy filler, and the content W of the fibrous filler _is 10 parts by mass relative to 100 parts by mass of the liquid crystal polyester. Parts to 50 parts by mass, relative to 100 parts by mass of the liquid crystal polyester, the content _W3 of the platy filler is 5 parts by mass to 30 parts by mass, (A): the primary particle diameter is 10 nm to 50 nm, (B ): DBP oil absorption is not less than 300cm ³ /100g and not more than 550cm ³ /100g. The liquid crystal polyester composition described in claim 1, wherein the BET specific surface area of the first carbon black is not less than 500m ² /g and not more than 1500m ² /g. The liquid crystal polyester composition as described in item 1 of the scope of the patent application, wherein the volume resistivity and content of the first carbon black, the volume resistivity and content of the aforementioned fibrous filler, and the volume resistivity of the aforementioned platy filler When the relationship with the content is represented by the ratio R ₁₂₃ represented by the following formula (S3), the ratio R ₁₂₃ is 1.1×10 ⁷ or more and 1×10 ⁹ or less,

ρ ₁ represents the volume resistivity of the aforementioned first carbon black, ρ ₂ represents the volume resistivity of the aforementioned fibrous filler, ρ ₃ represents the volume resistivity of the aforementioned platy filler, and W ₁ represents the volume resistivity relative to 100 parts by mass of the aforementioned liquid crystal polyester. For the content of the first carbon black, _W2 represents the content of the fibrous filler relative to 100 parts by mass of the liquid crystal polyester, and _W3 represents the content of the platy filler relative to 100 parts by mass of the liquid crystal polyester. The liquid crystal polyester composition as described in claim 3, wherein the volume resistivity ρ ₂ of the aforementioned fibrous filler is 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. below m. The liquid crystal polyester composition as described in claim 3 of the patent application, wherein the volume resistivity ρ ₃ of the plate-shaped filler is 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. below m. The liquid crystal polyester composition as described in claim 3, wherein the volume resistivity ρ ₁ of the first carbon black is 1×10 ² Ω. 1×10 ⁷ Ω above m. below m. The liquid crystal polyester composition according to any one of claims 1 to 6, wherein the flow initiation temperature of the liquid crystal polyester is not less than 280°C and not more than 420°C. The liquid crystal polyester composition as described in any one of items 1 to 6 of the scope of application, wherein the aforementioned liquid crystal polyester contains structural units (I) derived from aromatic hydroxycarboxylic acids, and structural units derived from aromatic diols. Structural unit (II) and structural unit (III) derived from aromatic dicarboxylic acid, relative to the total molar amount of all structural units constituting the aforementioned liquid crystal polyester, the content rate of the aforementioned structural unit (I) is 30 moles % to 80 mol%, relative to the total molar amount of all structural units constituting the aforementioned liquid crystal polyester, the content rate of the aforementioned structural unit (II) is 10 mol % to 35 mol %, relative to the total molar amount of the structural units constituting the aforementioned The total molar amount of all structural units of the liquid crystal polyester has a content rate of the aforementioned structural unit (III) of not less than 10 mol % and not more than 35 mol %. The liquid crystal polyester composition as described in item 7 of the scope of the patent application, wherein the aforementioned liquid crystal polyester contains a structural unit (I) derived from an aromatic hydroxycarboxylic acid, a structural unit (II) derived from an aromatic diol, and The structural unit (III) derived from an aromatic dicarboxylic acid has a content rate of 30 mol% or more and 80 mol% of the structural unit (I) relative to the total molar amount of all structural units constituting the liquid crystal polyester Hereinafter, with respect to the total molar amount of all structural units constituting the aforementioned liquid crystalline polyester, the content rate of the aforementioned structural unit (II) is not less than 10 mol% and not more than 35 mol%. The total molar amount of the unit is that the content rate of the structural unit (III) is not less than 10 mol % and not more than 35 mol %. The liquid crystal polyester composition as described in item 8 of the scope of the patent application, wherein the aforementioned aromatic hydroxycarboxylic acid-based p-hydroxybenzoic acid, the aforementioned aromatic diol-based hydroquinone and 4,4'-dihydroxybiphenyl at least one of the The aforementioned aromatic dicarboxylic acid is at least one selected from the group consisting of terephthalic acid and isophthalic acid. The liquid crystal polyester composition as described in item 9 of the scope of the patent application, wherein the aforementioned aromatic hydroxycarboxylic acid-based p-hydroxybenzoic acid, the aforementioned aromatic diol-based hydroquinone and 4,4'-dihydroxybiphenyl At least one of the aromatic dicarboxylic acids is at least one selected from the group consisting of terephthalic acid and isophthalic acid. A molded article containing the liquid crystal polyester composition described in any one of claims 1 to 11 of the patent application. The molded product as described in claim 12 of the patent application, which is used for the internal parts of the housing of electric/electronic equipment.