TW202003682A - 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 a liquid crystal polyester composition and its molded product.

The present invention claims priority based on Japanese Patent Application No. 2018-087696 filed on April 27, 2018, so the contents are cited here.

Image forming apparatuses such as laser printers or photocopiers that use an electrophotographic method are well known. Generally, the electrophotographic method has five steps of charging, exposing, developing, transferring and fixing (also called 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 developed using toner (developing step). Transfer the developed electrostatic image to copy paper (transfer step). The transferred electrostatic image is fixed by heating/pressure or solvent vapor (fixing step).

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

However, when the internal parts of the housing rub against the copy paper in this manner, static electricity may be generated. From the transfer step to the fixing step, the toner is electrostatically adhered to the copy paper. Therefore, if the charge amount of the internal parts of the casing that contacts the copy paper increases from the exposure step to the fixing step, the position of the transferred electrostatic image may shift. Then, in the subsequent fixing step, the electrostatic image is fixed in an offset state, thereby disturbing the obtained image.

In order to suppress the increase in the charge amount of the internal parts of the case, it is considered to add an additive material 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 electrical 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.

[Previous Technical Document] [Patent Literature]

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

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

However, the liquid crystal polyester composition of the method of Patent Document 2 may not sufficiently suppress the increase in the amount of charge.

In recent years, as the speed of image formation has increased, the transport speed of copy paper has gradually increased.

With the increase in the speed of conveying copy paper, the charge of the internal parts of the housing further increases, and the interference of the image also tends to become larger.

Further, the defects caused by the increase in the amount of charge are not only found in the image forming apparatus, but also in the internal parts of the casing of electric and electronic devices.

Therefore, there is a need for a molded product that can suppress an increase in the amount of charge and a liquid crystal polyester composition that can produce a molded product in this manner.

The present invention has been completed in view of such circumstances, and its object is to provide a molded product that can suppress an increase in the amount of charge and a liquid crystal polyester composition that can produce the molded product of this method.

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

However, as a result of in-depth discussion 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 to form an image on the copy paper is removed, making the transfer Electrostatic image is blurred.

The inventors set the upper limit value of the first carbon black content and the upper limit value of the carbon black content containing the first carbon black in order to adjust the absolute value of the charged amount, and found that the absolute value of the charged amount can be adjusted, and The present invention has been completed.

An aspect of the present invention provides a liquid crystal polyester composition containing a liquid crystal polyester and a carbon black, wherein the carbon black is composed of a first carbon black that satisfies the following conditions (A) and (B), and The second carbon black satisfying at least one of the conditions (A) and (B) is composed of 100 parts by mass of liquid crystal polyester, and the content of carbon black is 1 part by mass or more and 10 parts by mass or less; 100 parts by mass, the content W ₁ of the first carbon black is 1 part by mass or more and 10 parts by mass or less; the content of the second carbon black is 100 parts by mass or more and 9 parts by mass or less relative to 100 parts by mass of the liquid crystal polyester.

(A): The primary particle size is 10 nm or more and 50 nm or less.

(B): The DBP oil absorption is 300 cm ³ /100 g or more and 550 cm ³ /100 g or less.

The first carbon black can have a BET specific surface area of 500 m ² /g or more and 1500 m ² /g or less.

In one aspect of the present invention, it may be configured to contain a filler, and the filler may be a fibrous filler. The content W ₂ of the fibrous filler is 10 parts by mass or more and 130 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester.

In one aspect of the present invention, the ratio R ₁₂ represented by the following formula (S1) can be configured to exceed 1×10 ⁵ and not to reach 1×10 ¹¹ .

ρ ₁ represents the volume resistivity of the first carbon black. ρ ₂ represents the volume resistivity of the fibrous filler.

In one aspect of the present invention, a filler is contained. The filler may be a plate-shaped filler. The content W _{3 of the} plate-shaped filler may be 5 parts by mass or more and 80 parts by mass or less relative to 100 parts by mass of the liquid crystal polyester.

In one aspect of the present invention, the ratio R ₁₃ represented by the following formula (S2) may be configured to exceed 1×10 ⁵ and not to reach 1×10 ¹¹ .

ρ ₁ represents the volume resistivity of the first carbon black. ρ ₃ represents the volume resistivity of the plate-like filler.

In one aspect of the present invention, it may be configured to contain a filler, and the filler may be a fibrous filler and a plate-shaped filler. The content W ₂ of the fibrous filler is 10 parts by mass or more and 130 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester; the content W ₃ of the plate-like filler is 5 parts by mass or more and 80 parts by mass with respect 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 configured to exceed 1×10 ⁵ and not to reach 1×10 ¹¹ .

ρ ₁ represents the volume resistivity of the first carbon black. ρ ₂ represents the volume resistivity of the fibrous filler. ρ ₃ represents the volume resistivity of the plate-like 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. m or less.

In one aspect of the present invention, the volume resistivity ρ _{3 of the} plate-like filler may be constituted as 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. m or less.

In one aspect of the present invention, the volume resistivity ρ _{1 of the} first carbon black may be constituted as 1×10 ² Ω. 1×10 ⁷ Ω above m. m or less.

In one aspect of the present invention, the flow starting temperature of the liquid crystal polyester may be above 280°C and below 420°C.

In one aspect of the present invention, the liquid crystal polyester composition may also constitute a structural unit (I) derived from an aromatic hydroxycarboxylic acid, a structural unit (II) derived from an aromatic diol and an aromatic di The structural unit (III) of carboxylic acid, relative to the total structural unit of the liquid crystal polyester, the content rate of structural unit (I) is 30 mol% or more and 80 mol% or less; For the total unit, the content of structural unit (II) is 10 mol% or more and 35 mol% or less; relative to the total structural unit of liquid crystal polyester, the content of structural unit (III) is 10 mol% Above 35 mol% below.

In one aspect of the present invention, it may be constituted by 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.

An aspect of the present invention provides a molded product using the 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, "internal parts of the casing" in this specification means parts provided inside the casing.

That is, the present invention includes the following aspects.

[1] A liquid crystal polyester composition containing 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 second carbon black is a carbon black that does not satisfy at least one of the conditions (A) and (B).

The content W ₁ of the first carbon black is 1 part by mass or more and 10 parts by mass or less relative to 100 parts by mass of the liquid crystal polyester; the content of the second carbon black is 0 parts by mass relative to 100 parts by mass of the liquid crystal polyester. 9 parts by mass or less; and the total content of the first carbon black and the second carbon black is 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester.

(A): The primary particle size is 10 nm or more and 50 nm or less.

(B): The DBP oil absorption is 300 cm ³ /100 g or more and 550 cm ³ /100 g or less.

[2] The liquid crystal polyester composition according to [1], wherein the first carbon black has a BET specific surface area of 500 m ² /g or more and 1500 m ² /g or less.

[3] The liquid crystal polyester composition according to [1] or [2], further comprising a filler, the filler is a fibrous filler, and the fibrous filler is relative to 100 parts by mass of the liquid crystal polyester The content W ₂ is 10 parts by mass or more and 130 parts by mass or less.

[4] The liquid crystal polyester composition according to [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 does not reach 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 first carbon black. ρ ₂ represents the volume resistivity of the fibrous filler. W ₁ represents the content of the first carbon black relative to 100 parts by mass of the liquid crystal polyester. W ₂ represents The content of the fibrous filler relative to 100 parts by mass of the liquid crystal polyester.)

[5] The liquid crystal polyester composition according to [1] or [2], further comprising a filler, the filler being a plate-shaped filler, and the content W of the plate-shaped filler is 100 parts by mass of the liquid-crystalline polyester. ₃ is 5 parts by mass or more and 80 parts by mass or less.

[6] The liquid crystal polyester composition according to [5], wherein the relationship between the volume resistivity and content of the first carbon black and the volume resistivity and content of the plate-like filler is given by the following formula (S2) When the indicated ratio R _{13 is} expressed, the ratio R ₁₃ exceeds 1×10 ⁵ and does not reach 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 first carbon black. ρ ₃ represents the volume resistivity of the plate-like filler. W ₁ represents the content of the first carbon black relative to 100 parts by mass of the liquid crystal polyester. W ₃ It represents the content of the plate-like filler with respect to 100 parts by mass of the liquid crystal polyester.)

[7] The liquid crystal polyester composition described in [1] or [2] further contains a filler, and the filler is a fibrous filler and a plate-like filler.

The content W ₂ of the fibrous filler is 10 parts by mass or more and 130 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester, and the content W ₃ of the plate-like filler is 5 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. Above 80 parts by mass or less.

[8] The liquid crystal polyester composition according to [7], 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 given by the following formula (S3) When the expressed ratio R _{123 is} expressed, the ratio R ₁₂₃ exceeds 1×10 ⁵ and does not reach 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 first carbon black, the volume resistivity of the fibrous filler .ρ ₂ represents the volume resistivity of the plate-like filler .ρ ₃ represents a volume resistivity .W ₁ represented by mass with respect to 100 parts of the liquid crystal The content of the first carbon black in 100 parts by mass of polyester. W ₂ represents the content of the fibrous filler with respect to 100 parts by mass of the liquid crystal polyester. W ₃ represents the board with respect to 100 parts by mass of the liquid crystal polyester. The content of fillers.)

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

[10] The liquid crystal polyester composition according to [6] or [8], wherein the volume resistivity ρ ₃ of the plate-like filler is 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. m or less.

[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. m or less.

[12] The liquid crystal polyester composition according to any one of [1] to [11], wherein the flow starting temperature of the liquid crystal polyester is 280° C. or higher and 420° C. or lower.

[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 and is derived from an aromatic dicarboxylic acid The structural unit (II) of the alcohol and the structural unit (III) derived from the aromatic dicarboxylic acid have a content of 30 relative to the total molar amount of the entire structural unit constituting the liquid crystal polyester, and the structural unit (I) is 30 Molar% or more and 80 mol% or less, the content of the structural unit (II) is 10 mol% or more and 35 mol% or less with respect to the total molar amount of the entire structural units constituting the liquid crystal polyester The total molar amount of all structural units constituting the liquid crystal polyester, and the content rate 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 them.

The aforementioned aromatic dicarboxylic acid is at least one selected from the group consisting of terephthalic acid and isophthalic acid.

[15] A molded article containing the liquid crystal polyester composition according to any one of [1] to [14].

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

According to one aspect of the present invention, there is provided a molded product that can suppress an increase in the amount of charge, and a liquid crystal polyester composition that can produce the molded product in this manner.

<Liquid crystal polyester composition>

The liquid crystal polyester composition of this embodiment includes liquid crystal polyester and carbon black. In addition, the "carbon black" herein refers to a carbon black including only the first carbon black described later, or a carbon black including only 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, materials obtained by shaping the resulting mixture into pellets are also referred to as "compositions".

[Liquid Crystal Polyester]

The liquid crystal polyester of the present embodiment is one of thermotropic liquid crystal polymers. Regarding the liquid crystal polyester of this embodiment, a melt exhibiting optical anisotropy is formed at a temperature of 200°C or higher and 450°C or lower.

Specifically, examples of the liquid crystal polyester include: (1) a resin obtained by polymerizing aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, and aromatic diol, and (2) a polymer obtained by polymerizing plural kinds of aromatic hydroxycarboxylic acid 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.

Furthermore, in the production of liquid crystal polyesters, part or all of the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, and aromatic diol used as the raw material monomer may be prepared as an ester-forming derivative in advance and polymerized. By using the ester-forming derivative of this method, there is an advantage that the liquid crystal polyester can be manufactured more easily.

Examples of ester-forming derivatives include the following: As examples of ester-forming derivatives of aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids having a carboxyl group in the molecule, the aforementioned carboxyl group may be converted into a haloformyl group ( (I.e. acid halide), acetyloxycarbonyl (ie acid anhydride) and other highly reactive groups; the above-mentioned carboxyl group is produced by transesterification to form a polyester, and monohydric alcohols, glycols and other polyols, Phenols, etc. have formed esters.

Examples of polymerizable derivatives of compounds having phenolic hydroxyl groups such as aromatic hydroxycarboxylic acids and aromatic diols include the aforementioned phenolic hydroxyl groups, which are produced by transesterification to produce polyesters, and Those who form esters.

In addition, the aromatic ring of the above-mentioned aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, or aromatic diol may have a halogen atom such as a chlorine atom or a fluorine atom, methyl group, C1-C10 alkyl groups such as ethyl and butyl; C6-C20 aryl groups such as phenyl are used as substituents.

Examples of the aromatic hydroxycarboxylic acid include p-hydroxybenzoic acid (derived aromatic hydroxycarboxylic acid (A ₁ ) described later), m-hydroxybenzoic acid, and 6-hydroxy-2-naphthoic acid (derivative (A ₂ ) described later). Of aromatic hydroxycarboxylic acids), 3-hydroxy-2-naphthoic acid, 5-hydroxy-1-naphthoic acid, 4-hydroxy-4'-carboxydiphenyl ether, or the aromatic rings of these aromatic hydroxycarboxylic acids A part of the hydrogen atoms is substituted with at least one type of substituent selected from the group consisting of alkyl, aryl or halogen atoms to replace the aromatic hydroxycarboxylic acid formed. In the production of the liquid crystal polyester, the aforementioned aromatic hydroxycarboxylic acid may be used alone or in combination of two or more.

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

In addition, “derived from” in this specification means that the chemical structure is changed to polymerize the raw material monomer, and no other structural change occurs.

Examples of the aromatic dicarboxylic acid include terephthalic acid (derived (B ₁ ) aromatic dicarboxylic acid described later), isophthalic acid (derived (B ₂ ) aromatic dicarboxylic acid described later), and biphenyl -4,4'-dicarboxylic acid, 2,6-naphthalenedicarboxylic acid (derived aromatic dicarboxylic acid (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 the aromatic dicarboxylic acid, which is formed by selecting at least one kind of substituent to replace the group consisting of alkyl, aryl or halogen atoms Of aromatic dicarboxylic acids. In the production of the liquid crystal polyester, the aromatic dicarboxylic acid may be used alone or in combination of two or more.

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

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

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

Among the substituents that the aforementioned structural unit (structural unit derived from aromatic hydroxycarboxylic acid, structural unit derived from aromatic dicarboxylic acid, structural unit derived from aromatic diol) may be arbitrarily possessed, as an example of a halogen atom , A fluorine atom, a chlorine atom, a bromine atom can be cited; as examples of the alkyl group, a lower alkyl group having about 1 to 4 carbon atoms is preferred, and for example, a methyl group, an ethyl group, and a butyl group can be cited; as an example of the aryl group, List phenyl.

The following is a description of particularly preferred liquid crystal polyesters.

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

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

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

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

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

(d): combination (a) a structural unit in which (A ₁₎ a part or all of (A ₂₎ arthroplasty.

(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 ), a part or all of (C ₁ ) is replaced by (C ₃ ).

(g): combination (b) in the structural unit, (A ₂₎ a part or all of (A ₁₎ arthroplasty.

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

The content rate of the structural unit (I) derived from the aromatic hydroxycarboxylic acid is preferably 30 mol% or more and 80 mol% or less with respect to the total molar amount of all structural units constituting the liquid crystal polyester. In addition, the content rate of the structural unit (II) derived from the aromatic diol is preferably 10 mol% or more and 35 mol% or less with respect 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 10 mol% or more and 35 mol% or less with respect to the total molar amount of all structural units constituting the liquid crystal polyester. As the liquid crystal polyester, it is preferable to satisfy all such resins.

The content rate of the structural unit (A1) derived from p-hydroxybenzoic acid is preferably 30 mol% or more and 80 mol% or less with respect to the total molar amount of all structural units constituting the liquid crystal polyester. In addition, the content ratio of at least one of the structural unit derived from hydroquinone (C ₂ ) and the structural unit derived from 4,4′-dihydroxybiphenyl (C ₁ ) is relative to the entire structure constituting the liquid crystal polyester The total molar amount of units is preferably 10 mol% or more and 35 mol% or less. In addition, at least one kind of content ratio is selected from the group consisting of a structural unit derived from terephthalic acid (B ₁ ) and a structural unit derived from isophthalic acid (B ₂ ), with respect to the entire structure constituting the liquid crystal polyester The total molar amount of the unit is preferably 10 mol% or more and 35 mol% or less. As the liquid crystal polyester, it is preferable to satisfy all such resins.

As a method for producing the liquid crystal polyester, for example, a known method such as the method described in Japanese Patent Laid-Open No. 2002-146003 can be applied. That is, it may be mentioned that the above raw material monomers (aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol or ester-forming derivatives thereof) are melt polymerized (polycondensation) to obtain relatively low molecular weight Aromatic polyester (hereinafter simply referred to as "prepolymer"), a method of powdering the prepolymer and solid-phase polymerization by heating. By performing solid-phase polymerization in this way, the polymerization is further promoted, and a liquid crystal polyester of higher molecular weight can be obtained.

In addition, a method for manufacturing a liquid crystal polyester having a combination of the structural units (a) and (b) that belongs to 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. Examples of the catalyst in this case include metal compounds such as magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, and antimony trioxide; Nitrogen-containing heterocyclic compounds such as 4-(dimethylamino)pyridine and 1-methylimidazole are preferably nitrogen-containing heterocyclic compounds.

As the liquid crystal polyester used in the molded article of the present embodiment, a liquid crystal polyester having a flow starting temperature of 280° C. or higher produced by the following method is preferable. As described above, when solid-phase polymerization is used in the production of liquid crystal polyester, the flow starting temperature of the liquid crystal polyester can be set to 280° C. or higher in a relatively short time. In addition, by using the liquid crystal polyester having a flow initiation temperature of this method as the thermoplastic resin of the present embodiment, the resulting molded article has high heat resistance.

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

On the other hand, the flow starting temperature of the liquid crystal polyester used in the liquid crystal polyester composition of the present embodiment is preferably 280°C or higher and 420°C or lower, and more preferably 280°C or higher and 390°C or lower.

Here, for the flow starting temperature, a capillary rheometer equipped with a mold having an inner diameter of 1 mm and a length of 10 mm was used, and the liquid crystal polymer was heated at a heating rate of 4° C./min under a load of 9.8 MPa (100 kg/cm ² ). When the ester is extruded from the nozzle, it shows a melt viscosity of 4800 Pa.s (48000 poise). The flow initiation temperature is an indicator of the molecular weight of the liquid crystal polyester that is well known in the art. (Refer to the editor of Xiao Chuanzhi, "Synthesis, Forming, and Application of Liquid Crystalline Polymers," pages 95-105, CMC, published June 5, 1987). As a device for measuring the flow starting 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 method is excellent in heat resistance and fluidity during melting. Therefore, it is preferably used as a material for forming a molded product described later.

The liquid crystal polyester 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 the present 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 the present embodiment contains the first carbon black satisfying the following conditions (A) and (B).

On the other hand, the carbon black of the liquid crystal polyester composition of this embodiment includes only 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 conditions (A) and (B) and the second carbon black described later.

(A): The primary particle size is 10 nm or more and 50 nm or less.

(B): The DBP oil absorption is 300 cm ³ /100 g or more and 550 cm ³ /100 g or less.

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

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

When the primary particle size 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, it is possible to suppress an increase in the charged amount of the molded product.

When the primary particle size 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 manufacturing the liquid crystal polyester composition or molded product. In the molded product thus obtained, it is easy to make the surface resistance value of the inner surface of the molded product 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 size of the first carbon black is preferably 20 nm or more and 45 nm or less, and more preferably 30 nm or more and 40 nm or less.

The higher the DBP oil absorption of the first carbon black, the more voids near the surface of the first carbon black. When there are many voids near the surface of the first carbon black, the first carbon black in the liquid crystal polyester is easily pulled to each other and easily connected.

When the DBP oil absorption of the first carbon black is 300 cm ³ /100 g or more, the molded product formed of the liquid crystal polyester composition can be easily and sufficiently energized at the connection portion of the first carbon black. As a result, the surface resistance value of the molded product can be sufficiently reduced. Therefore, the increase in the amount of charge in the molded product can be sufficiently suppressed.

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

The DBP oil absorption of the first carbon black is 550cm ³ /100g or less. When the liquid crystal polyester, carbon black, and additives added as required are melt-kneaded, the viscosity of these mixtures will not become too high. As a result, the mixture becomes easy to granulate, and the liquid crystal polyester composition can be easily manufactured.

DBP oil absorption of the first carbon black is preferably 325cm ³ / 100g than 550cm ³ / 100g or less, and then the best of 350cm ³ / 100g than 525cm ³ / 100g or less.

BET specific surface area of the first carbon black is preferably 500m ² / g or more 1500m ² / g or less, and then the best of 700m ² / g or more 1350m ² / g or less, more preferably 750m ² / g or more 1300m ² / g or less.

In the present embodiment, the BET specific surface area of the carbon black is measured using a BET specific surface area measuring device (for example, AccuSorb 2100E manufactured by McMurraytic Instruments Co., Ltd.) at a temperature of liquid nitrogen, and the adsorption is measured. Volume and use the value calculated by the BET method.

Generally, the BET specific surface area of particles is affected by the particle size. However, in the first carbon black of the present 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 greater 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 product formed of the liquid crystal polyester composition can be easily and sufficiently energized at the connection portion of the first carbon black. As a result, the surface resistance value of the molded product can be sufficiently reduced. Therefore, it is possible to sufficiently suppress an increase in the charged amount of the molded product.

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 excessive. As described above, when the amount of voids formed by the first carbon black is excessive, when the liquid crystal polyester, carbon black, and additives added as required are melt-kneaded, the viscosity of the mixture becomes higher. As a result, the mixture becomes difficult to granulate, and it becomes difficult to produce 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 product is manufactured, when the liquid crystal polyester, carbon black, and additives added as needed are melt-kneaded, such mixture The viscosity will not become too high.

As a result, the mixture becomes easy to granulate, and the liquid crystal polyester composition can be easily produced.

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

When the volume resistivity ρ _{1 of the} first carbon black is within the above range, the surface resistance value of the molded article molded from the liquid crystal polyester composition can be sufficiently reduced. Therefore, it is possible to suppress an increase in the charged amount of the molded product.

In this embodiment, the volume resistivity of the first carbon black is after the first carbon black is left in a silicone dryer for 24 hours, at a measurement temperature of 23° C. and a humidity of 50%, using the insulation resistance tester R8340A Value measured by 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 mode may contain the second carbon black within a range that does not impair the effects of the present invention. The second carbon black does not satisfy at least one of condition (A) and condition (B).

(A): The primary particle size is 10 nm or more and 50 nm or less.

(B): The DBP oil absorption is 300 cm ³ /100 g or more and 550 cm ³ /100 g or less.

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 increase in viscosity of the liquid crystal polyester mixture when blended with the liquid crystal polyester. Therefore, in this embodiment, by using the first carbon black and the second carbon black together, a liquid crystal polyester composition that can suppress the increase in the viscosity of the liquid crystal polyester mixture and can suppress the increase in the amount of charge when used as a molded product is provided .

[Carbon Black Content]

In the liquid crystal polyester composition of the present embodiment, the content W ₁ of the first carbon black is 1 part by mass or more and 10 parts by mass or less with respect 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 crystal polyester composition can be sufficiently reduced. As a result, the increase in the amount of charge in the molded product can be suppressed.

Compared with the second carbon black, when the liquid crystal polyester, carbon black, and additives added as required 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 charged amount does not become excessively reduced. Therefore, by setting the content W _{1 of the} first carbon black within the range of 1 part by mass or more and 10 parts by mass or less, the absolute value of the amount of charge can be adjusted.

In the liquid crystal polyester composition of the present embodiment, the content W _{1 of the} first carbon black is preferably 2 parts by mass or more and 9 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester.

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

In the liquid crystal polyester composition of the present 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 relative to 100 parts by mass of the liquid crystal polyester. More than 10 parts by mass or less.

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 crystal polyester composition can be sufficiently reduced. Therefore, it is possible to suppress an increase in the charged amount of the molded product.

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

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

In the liquid crystal polyester composition of the present embodiment, the content of the carbon black is preferably 3 parts by mass or more and 9 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester.

[Filling material]

In addition to the liquid crystal polyester and the first carbon black, the liquid crystal polyester composition of the present embodiment preferably contains a filler. As a result, the strength or dimensional stability of the molded product molded from the liquid crystal polyester composition is improved.

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

On the other hand, the liquid crystal polyester composition of the present embodiment includes 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 plate-like filler. In addition, the liquid crystal polyester composition of the present embodiment preferably contains both the fibrous filler and the plate-like filler.

(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, silicon nitride whiskers and the like can also be cited.

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 the present embodiment, the content W _{2 of the} fibrous filler is preferably 10 parts by mass or more and 130 parts by mass or less, and more preferably 10 parts by mass or more and 80 parts by mass relative to 100 parts by mass of the liquid crystal polyester. It is preferably 10 parts by mass or more and 50 parts by mass or less, particularly preferably 10 parts by mass or more and 45 parts by mass or less. On the other hand, the content W _{2 of the} fibrous filler may be 23 parts by mass or more and 45 parts by mass or less.

When the content W ₂ of the fibrous filler is 10 parts by mass or more, the strength of the molded product after molding the liquid crystal polyester composition becomes very high.

When the content W ₂ 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 these mixtures 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 product 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 product tends to be uniform. As a result, even at any position on the inner surface of the molded product, an increase in the amount of charged electricity can be suppressed.

(Plate filler)

Examples of the plate-like filler include talc, mica, graphite, wollastonite, barium sulfate, calcium carbonate, and the like. Among them, the mica can also be muscovite, phlogopite, fluorophlogopite or tetrasilica.

In the liquid crystal polyester composition of the present embodiment, the content W _{3 of the} plate-like filler is preferably 5 parts by mass or more and 80 parts by mass or less, and more preferably 5 parts by mass or more and 50 parts by mass relative to 100 parts by mass of the liquid crystal polyester. It is preferably 5 parts by mass or more and 30 parts by mass or less, and particularly preferably 10 parts by mass or more and 25 parts by mass or less. On the other hand, the content W _{3 of the} plate-like filler may be 17 parts by mass or more and 23 parts by mass or less.

When the content W ₃ of the plate-like filler is 5 parts by mass or more, the dimensional stability or strength of the molded article molded from the liquid crystal polyester composition becomes very high.

When the content W ₃ of the plate-like filler is 80 parts by mass or less, when the liquid crystal polyester, carbon black, and plate-like filler are melt-kneaded, the viscosity of these mixtures 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 product 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 product tends to be uniform. As a result, even at any position on the inner surface of the molded product, an increase in the amount of charged electricity can be suppressed.

[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. Below m, more preferably 1×10 ¹⁰ Ω. 1×10 ¹³ Ω above m. m or less.

When the volume resistivity ρ _{2 of the} fibrous filler is within the above range, the surface resistance value of the molded article molded from the liquid crystal polyester composition can be sufficiently reduced. Therefore, it is possible to suppress an increase in the charged amount of the molded product.

The volume resistivity ρ _{3 of the} plate-like filler is preferably 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. Below m, more preferably 1×10 ¹⁰ Ω. 1×10 ¹³ Ω above m. m or less.

When the volume resistivity ρ _{3 of the} plate-like filler is within the above range, the surface resistance value of the molded article molded from the liquid crystal polyester composition can be sufficiently reduced. Therefore, it is possible to suppress an increase in the charged amount of the molded product.

In addition, the method of measuring the volume resistivity of the fibrous filler and the plate-like 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 a fibrous filler as a filler, the ratio R ₁₂ represented by the following formula (S1) is preferably more than 1×10 ⁵ and less than 1×10 ¹¹ , and It is preferably 1×10 ⁶ or more and 1×10 ¹⁰ or less, and more preferably 1×10 ⁷ or more and 1×10 ⁹ or less.

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

When the liquid crystal polyester composition of the present embodiment contains only a plate-like 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 . It is preferably 1×10 ⁵ or more and 1×10 ⁹ or less, and more preferably 5×10 ⁵ or more and 1×10 ⁸ or less.

As described above, ρ ₃ represents the volume resistivity of the plate-like filler. W ₃ represents the content (parts by mass) of the plate-like filler relative to 100 parts by mass of the liquid crystal polyester.

When the liquid crystal polyester composition of the present embodiment contains a fibrous filler and a plate-like filler as a filler, 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 1×10 ⁶ or more and 1×10 ¹⁰ or less, more preferably 1.1×10 ⁷ or more and 1×10 ⁹ or less.

In this embodiment, in order to control the absolute value of the amount of charge of the molded product, it is important not only to determine the volume resistivity of all components that can affect the amount of charge, but also to specify the content. 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 , of carbon black and fillers that can affect the charge W ₂ and W ₃ ) parameters of both. When the ratio R ₁₂ , the ratio R ₁₃ and the ratio R ₁₂₃ satisfy the desired range, the balance between the volume resistivity and the content can be adjusted, and the absolute value of the charged amount can be adjusted.

[Other ingredients]

The liquid crystal polyester composition of this embodiment mode may further contain components other than the fillers as long as the effects of the present invention are not impaired.

Examples of the above components include mold release modifiers such as fluororesins, metal soaps, etc.; colorants such as dyes and pigments; antioxidants; heat stabilizers; ultraviolet absorbers; antistatic agents; surfactants, etc., which are commonly used for molding Additives for the formation 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 surfactants.

In addition, examples of the above-mentioned components include thermosetting resins such as phenol resin, epoxy resin, and polyimide resin.

If the liquid crystal polyester composition having the above-mentioned components is used, a molded product with an adjustable absolute value of charge can be obtained.

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

<molded product>

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

The molded article of the present embodiment is a molded article used for the internal parts of the housing of electric and electronic equipment. Examples of electrical and electronic equipment include cameras, personal computers, mobile phones, smart phones, tablet computers, printers, and projectors. Examples of the internal parts of the housing of such electrical and electronic equipment include fixing parts for connectors, camera modules, fan machines, and printers.

The thickness of the molded product of the present embodiment is 0.1 mm or more, preferably 0.2 mm or more, more preferably 0.5 mm or more, and still more preferably 1 mm or more. 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 the present embodiment is 0.1 mm or more and 20 mm or less, preferably 0.2 mm or more and 20 mm or less, more preferably 0.5 mm or more and 20 mm or less, and still more preferably 1 mm or more and 20 mm or less.

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 is a fan or the like with uneven thickness, the thickness of the thinnest part may be 0.1 mm, preferably 0.2 mm or more, more preferably 0.5 mm or more, and still 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 non-contact three-dimensional measuring device is selected, the thickness of the molded product can be quantitatively obtained.

In the following, the case of fixing parts for a printer will be taken as an example for explaining the internal parts of the housing of an electric/electronic device, but the present embodiment is not limited to this.

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

In addition, as a result of intensive research, the inventors found that if the absolute value of the internal component charge between the exposure process and the fixing process is too low, even the static electricity required to form an image on the copy paper is removed, making the transfer Of the electrostatic image becomes blurred.

Then, in the subsequent fixing process, the electrostatic image is fixed in an offset state, which may eventually disturb the obtained image.

In the fixed part as the molded product of the present embodiment, the surface resistance value of the surface on the side in contact with the toner-coated copy paper is not more than 10 ¹² Ω and not more than 10 ¹⁵ Ω, preferably 10 ¹³ Ω or more Less than 10 ¹⁵ Ω. When the surface resistance value of the fixed part is 10 ¹² Ω or more, the charged amount of the molded product after contact with the copy paper does not become too low, and problems such as peeling of the toner adhering to the copy paper hardly occur. On the other hand, when the surface resistance value of the fixed part does not reach 10 ¹⁵ Ω, the charged amount of the molded product after contact with the copy paper does not become too high, and the toner adhering to the copy paper hardly occurs Problems such as stripping.

In addition, the surface resistance value of a molded product is the value measured using the well-known measuring apparatus based on "ASTM D257". The surface resistance value of the molded product, for example, can be based on the resistance measurement conditions based on "ASTM D257" (using a digital superinsulation/microampere meter "DSM-8104", manufactured by DKK-Toa Co., Ltd., measuring temperature 23C) Determination.

<Manufacturing method of molded product>

The method for manufacturing the molded product of the present embodiment is preferably a melt molding method, and examples thereof include injection molding, T-molding, inflation, and other extrusion molding methods, compression molding methods, blow molding methods, Vacuum forming method and press forming method. Among them, the injection molding method is preferred. In the following, as an example of the method of manufacturing a molded product of the present embodiment, the case of using the injection molding method will be described.

In the injection molding method in this embodiment mode, an injection molding machine (for example, Nissei Resin Industries Co., Ltd., "hydraulic horizontal molding machine PS40E5ASE type") may be used to melt the liquid crystal polyester composition and the molten liquid crystal polyester composition The object is heated to an appropriate temperature and injected into the mold to proceed.

The temperature at which the liquid crystal polyester composition is heated and melted for injection is set based on the flow starting temperature Tp°C of the liquid crystal polyester composition as a base point, and among them, preferably [Tp+10]°C or more and [Tp+50] Below ℃.

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

If a molded product having the above-mentioned composition is used, the absolute value of the charged amount can be adjusted.

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

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

According to one aspect of the present invention, one embodiment of the liquid crystal polyester composition includes a liquid crystal polyester, a first carbon black, and a second carbon black as required, and a filler; the aforementioned liquid crystal polyester, It contains only structural units derived from p-hydroxybenzoic acid (the total molar amount relative to the total structural units constituting the liquid crystal polyester is 30 mol% or more and 80 mol% or less), derived from 4,4'-dihydroxy Structural units of biphenyl (the total molar amount relative to the total structural units constituting the liquid crystal polyester is 10 mol% or more and 35 mol% or less), structural units derived from terephthalic acid (relative to the liquid crystal polyester The total molar amount of the total structural units is 10 mol% or more and 35 mol% or less), and the structural units of isophthalic acid (relative to the total structural units constituting the liquid crystal polyester are 10 mols % Or more and 35 mol% or less) liquid crystal polyester; the aforementioned first carbon black has a primary particle size of 30 nm or more and 40 nm or less, and the DBP oil absorption is 350 cm ³ /100 g or more and 525 cm ³ /100 g or less; the aforementioned first Two carbon blacks are DBP oil absorption not satisfying the conditions of 300cm ³ /100g or more and 550cm ³ /100g or less.

The filler material is a fibrous filler (preferably glass fiber) and a plate-shaped filler (preferably talc); the content of the liquid crystal polyester is 30 to 90% by mass relative to the total mass of the liquid crystal polyester composition; The content W ₁ of the first carbon black is 2 parts by mass or more and 9 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester, and the content of the second carbon black is 0 parts by mass with respect to 100 parts by mass of the liquid crystal polyester. 3 parts by mass or less, and the total content of the first carbon black and the second carbon black is 3 parts by mass or more and 9 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester; The content W ₂ of the fibrous filler is 23 parts by mass or more and 45 parts by mass or less; the content W ₃ of the plate-like filler is 17 parts by mass or more and 23 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester; the first carbon black The relationship between the volume resistivity ρ ₁ and the content W ₁ , the volume resistivity ρ ₂ and the content W _{2 of the} fibrous filler, and the volume resistivity ρ ₃ and the content W _{3 of the} plate-shaped filler are given by ( When the ratio R ₁₂₃ described in S3) is expressed, the ratio R ₁₂₃ exceeds 4×10 ⁷ and does not reach 5.8×10 ⁸ .

In addition, the liquid crystal polyester may have a BET specific surface area of the first carbon black of 750 m ² /g or more and 1300 m ² /g or less.

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 may be 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. m or less, the volume resistivity ρ _{3 of the} aforementioned plate-like filler may be 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. m or less.

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

(A): The primary particle size is 10 nm or more and 50 nm or less.

(B): The DBP oil absorption is 300 cm ³ /100 g or more and 550 cm ³ /100 g or less.

[Example]

Hereinafter, the present invention will be described by examples, but the present invention is not limited to these examples. In addition, in this embodiment, the fixed parts for printers are assumed to be evaluated before being used as molded products, but the use of molded products is not limited to this.

Each molded product was evaluated by the following method.

<Measurement of surface resistance value>

Surface resistance value of molded product. The resistance measurement conditions based on "ASTM D257" (using a digital superinsulation/microampere meter "DSM-8104", manufactured by DKK Co., Ltd., East Asia) were used to measure at a measurement temperature of 23°C.

<Measurement of the absolute value of the charged amount>

The test pieces (molded products) of the examples and comparative examples were stacked on fixed copy paper, and the test pieces were reciprocated in a single direction under the following conditions to perform the test. The absolute value of the charged 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 Xindong Science Co., Ltd.)

Weight: 5 grams

Reciprocating distance: 60mm

Moving speed: 4000mm/min

Reciprocating times: 50 times

Evaluation environment: temperature 23℃, humidity 50%

<Measurement of volume resistivity>

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

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

In a reactor equipped with a stirrer, torque meter, nitrogen inlet tube, thermometer and reflux condenser, put 994.5g (7.2 mol) of p-hydroxybenzoic acid and 446.9g (2.4,4'-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, then 0.18 g of 1-methylimidazole was added, and while stirring in a nitrogen stream, the temperature was raised from room temperature (23°C) to 150°C within 30 minutes, and 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 within 2 hours and 50 minutes, and by-product acetic acid and unreacted acetic anhydride were distilled off. When torque increase was observed, The content was taken out of the reactor and cooled to room temperature to obtain a prepolymer as a solid.

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

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

In a reactor equipped with a stirrer, torque meter, nitrogen inlet tube, thermometer and reflux condenser, put 994.5g (7.2 mol) of p-hydroxybenzoic acid and 446.9g (2.4,4'-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, then 0.18 g of 1-methylimidazole was added, and while stirring in a nitrogen stream, the temperature was raised from room temperature (23°C) to 150°C within 30 minutes, and 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 within 2 hours and 50 minutes, and by-product acetic acid and unreacted acetic anhydride were distilled off. When an increase in torque was observed, the contents were taken out of the reactor and cooled to room temperature to obtain a solid prepolymer.

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

In addition, the following materials were used as carbon black and filler. The physical properties of carbon black and fillers are the manufacturer's nominal values.

[Carbon Black]

The 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

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

[Fibrous filler]

Glass fiber (1): CS3J260S (manufactured by Nitto Textile 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 filler]

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

The fillers used, whose ratio R ₁₂₃ represented by the following formula (S3), are 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 Chibei Iron Works Co., Ltd.), liquid crystal polyester, carbon black, and optionally added at a cylinder temperature of 340°C at the ratios shown in Table 1 and Table 2 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 using an injection molding machine ("PNX40-5A", manufactured by Nissei Resin Co., Ltd.) at a molding temperature of 350°C, a mold temperature of 130°C, and an injection speed of 100 mm/sec. Then, a flat test piece with a thickness of 1 mm was formed.

The comprehensive evaluation of Examples and Comparative Examples is shown in Table 3 and Table 4. Using the absolute value of the granulation property and the charged amount of the test piece and the copy paper after the test, the comprehensive evaluation of Examples and Comparative Examples was performed according to the following criteria. In addition, 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 it cannot be granulated is evaluated as "B".

A: Granulation is "A", and the absolute value of the charged amount of the test piece is 30V or more and 200V or less, and the absolute value of the charged amount of the copy paper is 0V or more and 5V or less.

B: Other.

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

On the other hand, the test pieces of Examples 1 to 6 to which the present invention is applied have surface resistance values compared with the test pieces of Comparative Example 3. In addition, in Examples 1 to 6 to which the present invention is applied, compared with Comparative Example 3, the absolute value of the charged amount of the test piece after the test is larger.

From this, it can be seen that in the present invention, the surface resistance value of the test piece can be adjusted to not more than 10 ¹² Ω by taking the content of the first carbon black and the total content of the first carbon black and the second carbon black as specific ranges. Within the range of 10 ¹⁵ Ω, the increase in the amount of charge 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 use possibility]

The present invention is extremely useful in industry because it can provide a molded product that can suppress an increase in the amount of charge and a liquid crystal polyester composition that can obtain such a molded product.

Claims (16)

A liquid crystal polyester composition containing a liquid crystal polyester, a first carbon black, and a second carbon black according to demand. The first carbon black is a carbon black satisfying the following conditions (A) and (B). The two-carbon black-based carbon black does not satisfy at least one of the conditions (A) and (B), and the content W ₁ of the first carbon black is 1 part by mass or more relative to 100 parts by mass of the liquid crystal polyester. Less than 100 parts by mass; The content of the second carbon black is 0 parts by mass or more and 9 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester; The first carbon black and the second carbon are relative to 100 parts by mass of the liquid crystal polyester The total content of black is 1 part by mass or more and 10 parts by mass or less, (A): primary particle size is 10 nm or more and 50 nm or less, (B): DBP oil absorption is 300 cm ³ /100 g or more and 550 cm ³ /100 g or less. The liquid crystal polyester composition as described in item 1 of the patent application range, wherein the first carbon black has a BET specific surface area of 500 m ² /g or more and 1500 m ² /g or less. The liquid crystal polyester composition as described in item 1 or 2 of the patent application scope, which additionally contains a filler, the filler is a fibrous filler, and the content W of the fibrous filler is 100 parts by mass of the liquid crystal polyester ₂ is 10 parts by mass or more and 130 parts by mass or less. The liquid crystal polyester composition according to item 3 of the patent application scope, 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 given by the following formula (S1) When the represented ratio R ₁₂ represents, the ratio R ₁₂ is more than 1×10 ⁵ and less than 1×10 ¹¹ ,

ρ ₁ represents the volume resistivity of the first carbon black, ρ ₂ represents the volume resistivity of the fibrous filler, W ₁ represents the content of the first carbon black relative to 100 parts by mass of the liquid crystal polyester, and W ₂ represents the relative The content of the fibrous filler in 100 parts by mass of the liquid crystal polyester. The liquid crystal polyester composition as described in item 1 or 2 of the patent application scope further contains a filler, and the filler is a plate-like filler, and the content W ₃ of the plate-like filler is 100 parts by mass of the liquid crystal polyester, and 5 parts by mass or more and 80 parts by mass or less. The liquid crystal polyester composition as described in item 5 of the patent application scope, wherein the relationship between the volume resistivity and content of the first carbon black and the volume resistivity and content of the plate filler is given by the following formula (S2) When the represented ratio R ₁₃ represents, the ratio R ₁₃ is more than 1×10 ⁵ and less than 1×10 ¹¹ ,

ρ ₁ represents the volume resistivity of the first carbon black, ρ ₃ represents the volume resistivity of the plate filler, W ₁ represents the content of the first carbon black relative to 100 parts by mass of the liquid crystal polyester, and W ₃ represents the relative The content of the plate-like filler is 100 parts by mass of the liquid crystal polyester. The liquid crystal polyester composition as described in item 1 or 2 of the patent application scope further contains a filler, the filler is a fibrous filler and a plate-like filler, and the fibrous filler is relative to 100 parts by mass of the liquid crystal polyester The content W ₂ is 10 parts by mass or more and 130 parts by mass or less, and the content W ₃ of the plate-like filler is 5 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester. The liquid crystal polyester composition according to item 7 of the patent application scope, wherein the volume resistivity and content of the first carbon black, the volume resistivity and content of the fibrous filler and the volume resistivity of the plate filler And the relationship between the content, represented by the following formula (S3) represented by the ratio R ₁₂₃ , the ratio R ₁₂₃ is more than 1×10 ⁵ and less than 1×10 ¹¹ ,

ρ ₁ represents the volume resistivity of the first carbon black, ρ ₂ represents the volume resistivity of the fibrous filler, ρ ₃ represents the volume resistivity of the plate filler, and W ₁ represents 100 parts by mass relative to the liquid crystal polyester For the content of the first carbon black, W ₂ represents the content of the fibrous filler with respect to 100 parts by mass of the liquid crystal polyester, and W ₃ represents the content of the plate-like filler with respect to 100 parts by mass of the liquid crystal polyester. The liquid crystal polyester composition as described in item 4 or 8 of the patent application, wherein the volume resistivity ρ ₂ of the fibrous filler is 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. m or less. The liquid crystal polyester composition as described in item 6 or 8 of the patent application, wherein the volume resistivity ρ ₃ of the plate-like filler is 1×10 ⁹ Ω. 1×10 ¹⁵ Ω above m. m or less. The liquid crystal polyester composition according to item 4, 6 or 8 of the patent application range, wherein the volume resistivity ρ ₁ of the first carbon black is 1×10 ² Ω. 1×10 ⁷ Ω above m. m or less. The liquid crystal polyester composition according to any one of claims 1 to 11, wherein the liquid crystal polyester has a flow starting temperature of 280°C or higher and 420°C or lower. The liquid crystal polyester composition according to any one of claims 1 to 12, wherein the liquid crystal polyester contains a structural unit (I) derived from an aromatic hydroxycarboxylic acid and an aromatic diol derived from The structural unit (II) and the structural unit (III) derived from aromatic dicarboxylic acid have a content of 30 mol relative to the total molar amount of all structural units constituting the liquid crystal polyester, and the structural unit (I) % Or more and 80 mol% or less, with respect to the total mol amount of all structural units constituting the liquid crystal polyester, the content rate of the structural unit (II) is 10 mol% or more and 35 mol% or less, relative to the composition The total molar amount of all structural units of the liquid crystal polyester, the content rate of the structural unit (III) is 10 mol% or more and 35 mol% or less. The liquid crystal polyester composition according to item 13 of the patent application range, wherein the aromatic hydroxycarboxylic acid-based p-hydroxybenzoic acid, the aromatic diol-based hydroquinone and 4,4'-dihydroxybiphenyl At least one of the aromatic dicarboxylic acids is selected from the group consisting of terephthalic acid and isophthalic acid. A molded product containing the liquid crystal polyester composition according to any one of the patent application items 1 to 14. The molded product as described in item 15 of the patent application scope is used for the internal parts of the housing of electric/electronic equipment.