Liquid crystal polyester composition and method for producing same

Abstract

A liquid crystal polyester composition containing a liquid crystal polyester and a fibrous filler (A), the proportion of a fibrous filler (A-1) having a fiber length of 50 [mu] m or less in the fibrous filler (A) being 0.5 mass% or less.

Description

Technical Field

[0001] This disclosure relates to liquid crystal polyester compositions and methods for manufacturing the same. Background Technology

[0002] Liquid crystal polyester is used in a variety of applications due to its high fluidity, heat resistance and dimensional accuracy.

[0003] Liquid crystal polyesters are typically used as liquid crystal polyester compositions containing fillers to meet the required properties for their respective applications. For example, Patent Document 1 describes a liquid crystal polyester composition containing glass fibers having a non-circular cross-sectional shape.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2008-013703 Summary of the Invention

[0005] The problem that the invention aims to solve However, conventional liquid crystal polyester compositions have the problem of generating trace amounts of gas from the surface of the molded product under high temperature conditions.

[0006] The purpose of this disclosure is to provide a liquid crystal polyester composition capable of forming molded articles that suppress the generation of gases (especially high-boiling-point components) under high-temperature environments. Another purpose of this disclosure is to provide a method for manufacturing the liquid crystal polyester composition.

[0007] Methods for solving problems This disclosure provides, for example, the following.

[0008] [1] A liquid crystal polyester composition, wherein, It contains liquid crystal polyester and fibrous filler (A). The proportion of fibrous filler (A-1) with a fiber length of less than 50 μm in the above fibrous filler (A) is less than 0.5% by mass.

[0009] [2] According to the liquid crystal polyester composition of [1], wherein, The proportion of fibrous filler (A-2) with a fiber length of 10 μm or more and 75 μm or less in the above-mentioned fibrous filler (A) is 0% or more and 1% or less by mass.

[0010] [3] The liquid crystal polyester composition according to [1] or [2], wherein, The fibrous filler (A) mentioned above contains glass fibers.

[0011] [4] The liquid crystal polyester composition according to any one of [1] to [3], wherein, The content of the above-mentioned fibrous filler (A) is 5% by mass or more and 35% by mass or less.

[0012] [5] The liquid crystal polyester composition according to any one of [1] to [4], wherein, The aforementioned liquid crystal polyester contains monomer units derived from aromatic hydroxycarboxylic acids.

[0013] [6] The liquid crystal polyester composition according to [5], wherein, The content of the aforementioned monomer units is 50 mol% or more relative to the total number of monomer units constituting the aforementioned liquid crystal polyester.

[0014] [7] A method for manufacturing a liquid crystal polyester composition, wherein, This includes a mixing step of mixing liquid crystal polyester with fibrous fillers to obtain a liquid crystal polyester composition. The above-mentioned mixing process is a process of mixing the liquid crystal polyester with the fibrous filler in such a way that the proportion of the fibrous filler (A-1) with a fiber length of 50 μm or less in the fibrous filler (A) is 0.5% by mass or less.

[0015] Invention Effects According to this disclosure, a liquid crystal polyester composition capable of forming molded articles that suppress the generation of gases (especially high-boiling-point components) under high-temperature environments can be provided. Furthermore, according to this disclosure, a method for manufacturing the liquid crystal polyester composition can be provided. Detailed Implementation

[0016] Hereinafter, a preferred embodiment of the present disclosure will be described in detail.

[0017] The liquid crystal polyester composition of this embodiment (hereinafter also simply referred to as "liquid crystal polyester composition") comprises liquid crystal polyester and fibrous filler (fibrous filler (A)). The proportion of fibrous filler (A-1) with a fiber length of 50 μm or less in fibrous filler (A) is 0.5% by mass or less.

[0018] If the liquid crystal polyester composition of this embodiment is used, it is possible to form a molded article that suppresses the generation of gases (especially high-boiling-point components) in a high-temperature environment.

[0019] The reasons for achieving this effect are as follows.

[0020] In the liquid crystal polyester composition of this embodiment, the amount of fibrous filler (A-1) with a fiber length of 50 μm or less is small, while the amount of fibrous filler (A') with a fiber length of more than 50 μm is large. In this embodiment, because there is a large amount of fibrous filler with a fiber length of more than 50 μm, the fibrous filler (A') is easily exposed to the surface during the molding of the liquid crystal polyester composition. With the fibrous filler (A') exposed to the surface, gaseous components (especially high-boiling-point components) inside the composition are easily volatilized and discharged outside the composition by heating during molding. That is, it is considered that in the molded article formed from the liquid crystal polyester composition of this embodiment, components that are the cause of gas generation are removed beforehand by heating during molding, resulting in a small amount of gas generated at high temperatures.

[0021] (1) Liquid crystal polyester Liquid crystal polyesters are any polyesters that exhibit liquid crystal properties in the molten state. A liquid crystal polyester composition may contain only one type of liquid crystal polyester, or it may contain two or more types.

[0022] The flow initiation temperature of liquid crystal polyester can be above 250°C or above 270°C. Furthermore, the flow initiation temperature of liquid crystal polyester can be below 400°C, below 360°C, or below 340°C.

[0023] That is, the flow start temperature of the liquid crystal polyester can be, for example, above 250°C and below 400°C, above 250°C and below 360°C, above 250°C and below 340°C, above 270°C and below 400°C, above 270°C and below 360°C, or above 270°C and below 340°C.

[0024] In this specification, the flow initiation temperature of the liquid crystal polyester is determined using a flow tester, wherein one side of the liquid crystal polyester is subjected to a flow tester at 9.8 MPa (100 kg / cm²). 2 Under a load of 4°C / min, the temperature was increased to melt the liquid crystal polyester, which was then extruded from a nozzle with an inner diameter of 1 mm and a length of 10 mm. The viscosity of the liquid crystal polyester was 4800 Pa·s (48000 poise).

[0025] Liquid crystal polyesters have constituent units derived from raw material monomers (also called monomer units). Liquid crystal polyesters may also have monomer units whose main monomer units (e.g., monomer units whose total percentage relative to all monomer units is 90 mol% or more, 95 mol% or more, or 99 mol% or more, preferably all monomer units) are derived from aromatic compounds. Liquid crystal polyesters in which all monomer units are derived from aromatic compounds are also called fully aromatic liquid crystal polyesters.

[0026] Typical examples of liquid crystal polyesters include polymers having monomer units derived from aromatic hydroxycarboxylic acids (preferably polymers having two or more monomer units derived from aromatic hydroxycarboxylic acids), polymers having monomer units derived from aromatic dicarboxylic acids and monomer units derived from aromatic diols, and polymers having monomer units derived from aromatic hydroxycarboxylic acids, monomer units derived from aromatic dicarboxylic acids, and monomer units derived from aromatic diols.

[0027] As monomeric units derived from aromatic hydroxycarboxylic acids, examples include monomeric units represented by formula (I) below. As monomeric units derived from aromatic dicarboxylic acids, examples include monomeric units represented by formula (II) below. As monomeric units derived from aromatic diols, examples include monomeric units represented by formula (III) below (where X and Y are oxygen atoms).

[0028] It should be noted that, in this specification, "source" refers to a change in the chemical structure of the functional groups that facilitate polymerization in the monomer units of the liquid crystal polyester formed by the polymerization of the raw material monomers, without any other structural changes. The term "source" here also includes cases where the source is a polymerizable derivative of the raw material monomer (e.g., a compound formed by converting the polymerizable functional groups of the raw material monomer into other polymerizable groups).

[0029] Liquid crystal polyesters may have monomer units represented by the following formula (I) (hereinafter also referred to as "monomer unit (I)"). It should be noted that in this specification, CO in the formula represents a carbonyl group.

[0030] -O-Ar 1 -CO- (I) [In the formula, Ar] 1 This indicates phenylene, naphthylene, or biphenylene. Ar 1 Some or all of the hydrogen atoms in the represented group may be replaced by halogen atoms, alkyl groups, or aryl groups. The liquid crystal polyester may further have monomer units represented by formula (II) below (hereinafter also referred to as "monomer unit (II)"). and / or monomer units represented by formula (III) below (hereinafter also referred to as "monomer unit (III)").

[0031] -CO-Ar 2 -CO- (II) -X-Ar 3 -Y- (III) [In the formula, Ar] 2 and Ar 3Each of these groups independently represents a phenylene, naphthylene, biphenylene, or a group represented by formula (IV) below. X and Y independently represent an oxygen atom or an imino group (-NH-). 2 The hydrogen atoms in the represented group may be partially or completely replaced by halogen atoms, alkyl groups, or aryl groups. 3 Some or all of the hydrogen atoms in the represented group may be replaced by halogen atoms, alkyl groups, or aryl groups. -Ar 4 -Z-Ar 5 - (IV) [In the formula, Ar] 4 and Ar 5 Each can be represented independently as either phenylene or naphthylene. Z represents an oxygen atom, sulfur atom, carbonyl group, sulfonyl group, or alkane dimethyl group. As can be compared with Ar 1 Ar 2 Or Ar 3 The halogen atoms that are replaced by hydrogen atoms can be listed as fluorine, chlorine, bromine and iodine atoms.

[0032] Can be used with Ar 1 Ar 2 Or Ar 3 The alkyl group substituted with hydrogen atoms can be straight-chain, branched, or cyclic. For example, the alkyl group can be an alkyl group having 1 to 10 carbon atoms. Examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-hexyl, 2-ethylhexyl, n-octyl, and n-decyl.

[0033] Can be used with Ar 1 Ar 2 Or Ar 3 The aryl group substituted with hydrogen atoms can be either monocyclic or condensed. For example, aryl groups can have 6 to 20 carbon atoms. Examples of aryl groups include phenyl, o-tolyl, m-tolyl, p-tolyl, 1-naphthyl, and 2-naphthyl. Aryl groups can also be groups obtained by substituting the hydrogen atoms of the aromatic ring with alkyl groups, such as tolyl.

[0034] In Ar 1 Ar 2 Or Ar 3 When the hydrogen atoms are replaced by the aforementioned groups, the number of substitutions can be one, two, or one.

[0035] The alkane dimethyl group in Z can be straight-chain or branched. The alkane dimethyl group can be an alkane dimethyl group with 1 to 10 carbon atoms. Examples of alkane dimethyl groups include methylene, ethane dimethyl, propane dimethyl (e.g., propane-2,2-dimethyl), butane dimethyl, octane dimethyl (e.g., octane-3,3-dimethyl), etc.

[0036] The single-unit (I) can be, for example, Ar. 1 The monomer unit of the phenylene group, Ar 1 The monomeric unit of naphthyl or Ar 1 It is a monomeric unit of biphenylene, and can also be Ar. 1 The monomer unit of the phenylene or Ar 1 It is a monomeric unit of naphthylene, or it can be Ar. 1 It is a monomeric unit of 1,4-phenylene or Ar 1 The monomer unit is 2,6-naphthylene. Liquid crystal polyesters may also have one or more monomer units (I).

[0037] Monomer unit (II) can be, for example, Ar 2 The monomer unit of the phenylene group, Ar 2 The monomer unit of naphthylene, Ar 2 It is a monomeric unit of biphenylene, or Ar 2 It is a monomeric unit of diphenyl ether-diyl, or it can be Ar. 2 The monomer unit of the phenylene group, Ar 2 It is a monomeric unit of naphthylene, or Ar 2 It is a monomeric unit of biphenylene, and can also be Ar. 2 It is a monomeric unit of phenylene, or Ar 2 The monomer unit is naphthylene. The phenylene group can be 1,4-phenylene or 1,3-phenylene. The naphthyl group can be 2,6-naphthylene or 2,7-naphthylene. The biphenylene group can be 4,4'-biphenylene. The diphenyl ether-diyl group can be diphenyl ether-4,4'-diyl. Liquid crystal polyesters may also have one or more monomer units (II).

[0038] Monomer unit (II) can be, for example, Ar 2 The monomer unit is 1,4-phenylene, Ar 2 The monomer unit is 1,3-phenylene, Ar 2 It is a 2,6-naphthyl monomer unit, Ar 2 It is a 2,7-naphthyl monomer unit, Ar 2 It is a monomeric unit of 4,4'-biphenylene, or Ar 2 It is a monomeric unit of diphenyl ether-4,4'-diyl, and can also be Ar. 2The monomer unit is 1,4-phenylene, Ar 2 It is a monomeric unit of 1,3-phenylene, or Ar 2 It is a 2,6-naphthyl monomer unit.

[0039] Monomer unit (III) can be, for example, Ar 3 The monomer unit of the phenylene group, Ar 3 It is a monomeric unit of naphthylene, or Ar 3 It is a monomeric unit of biphenylene, and can also be Ar. 3 It is a monomeric unit of phenylene, or Ar 3 It is a monomeric unit of biphenylene, and can also be Ar. 3 It is a monomeric unit of 1,4-phenylene, or Ar 3 The monomer unit is 4,4'-biphenylene. Liquid crystal polyesters may also have one or more monomer units (III).

[0040] Monomer unit (III) can also be a monomer unit (III) with X and Y being oxygen atoms respectively.

[0041] The single-unit element (I) can be the single-unit element represented by the following formula (Ia) (hereinafter also referred to as "single-unit element (Ia)"). The single-unit element (II) can be the single-unit element represented by the following formula (IIa) (hereinafter also referred to as "single-unit element (IIa)"). The single-unit element (III) can be the single-unit element represented by the following formula (IIIa) (hereinafter also referred to as "single-unit element (IIIa)").

[0042] -O-Ar 11 -CO- (Ia) -CO-Ar 12 -CO- (IIa) -O-Ar 13 -O- (IIIa) [In the formula, Ar] 11 It represents 1,4-phenylene or 2,6-naphthylene.

[0043] Ar 12 It represents 1,4-phenylene, 1,3-phenylene, 2,6-naphthylene, 2,7-naphthylene, 4,4'-biphenylene, or diphenyl ether-4,4'-diyl.

[0044] Ar 13 It represents 1,4-phenylene or 4,4'-biphenylene.

[0045] Ar 11 Ar 12 Or Ar 13Some or all of the hydrogen atoms in the represented group may be independently replaced by a halogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms. Liquid crystal polyesters can be polymers having monomer units (Ia), polymers having monomer units (Ia) and monomer units (IIa), or polymers having monomer units (Ia), monomer units (IIa) and monomer units (IIIa).

[0046] The liquid crystal polyester preferably has monomer units derived from aromatic hydroxycarboxylic acids (hereinafter also referred to as "monomer unit A"). The majority (e.g., more than 50 mol%) of the monomer units may be monomer unit A, or all of the monomer units may be monomer unit A.

[0047] The liquid crystal polyester may also have at least one monomer unit selected from the group consisting of monomer units derived from p-hydroxybenzoic acid and monomer units derived from 2-hydroxy-6-naphthoic acid as monomer unit A.

[0048] The number of monomer units A in the liquid crystal polyester having monomer unit A, relative to the total number of monomer units in the liquid crystal polyester, may be 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 55 mol% or more, or 60 mol% or more. Furthermore, the number of monomer units A in the liquid crystal polyester having monomer unit A, relative to the total number of monomer units in the liquid crystal polyester, may be 100 mol% or less, 95 mol% or less, 90 mol% or less, 85 mol% or less, or 80 mol% or less.

[0049] That is, the number of monomer units A in the liquid crystal polyester relative to the total number of monomer units in the liquid crystal polyester can be, for example, 20 mol% or more and 100 mol% or less, 20 mol% or more and 95 mol% or less, 20 mol% or more and 90 mol% or less, 20 mol% or more and 85 mol% or less, 20 mol% or more and 80 mol% or less, 30 mol% or more and 100 mol% or less, 30 mol% or more and 95 mol% or less, 30 mol% or more and 90 mol% or less, 30 mol% or more and 85 mol% or less, 30 mol% or more and 80 mol% or less, 40 mol% or more and 100 mol% or less, 40 mol% or more and 95 mol% or less, 40 mol% or more and 90 ... Below 85 mol%, above 40 mol% and below 80 mol%, above 50 mol% and below 100 mol%, above 50 mol% and below 95 mol%, above 50 mol% and below 90 mol%, above 50 mol% and below 85 mol%, above 50 mol% and below 80 mol%, above 55 mol% and below 100 mol%, above 55 mol% and below 95 mol%, above 55 mol% and below 90 mol%, above 55 mol% and below 85 mol%, above 55 mol% and below 80 mol%, above 60 mol% and below 100 mol%, above 60 mol% and below 95 mol%, above 60 mol% and below 90 mol%, above 60 mol% and below 85 mol%, or above 60 mol% and below 80 mol%.

[0050] When the liquid crystal polyester is a polymer having two or more monomer units (I), at least one of the monomer units (I) has an Ar 1 It can be naphthylene. When the liquid crystal polyester is a polymer having monomer units (I) and monomer units (II), the Ar of monomer unit (I) 1 and Ar of the monomer unit (II) 2 At least one of them can be naphthylene. When the liquid crystal polyester is a polymer having monomer units (I), monomer units (II), and monomer units (III), the Ar of monomer unit (I) 1 Ar of the single unit (II) 2 Ar of the single unit (III) 3 At least one of them can be a naphthyl group.

[0051] When the liquid crystal polyester has monomer units (I), monomer units (II), and monomer units (III), the number of monomer units (I) relative to the total number of monomer units in the liquid crystal polyester can be, for example, 30 mol% or more, 40 mol% or more, 45 mol% or more, 50 mol% or more, or 55 mol% or more. Furthermore, when the liquid crystal polyester has monomer units (I), monomer units (II), and monomer units (III), the number of monomer units (I) relative to the total number of monomer units in the liquid crystal polyester can be, for example, 80% or less, or 70% or less.

[0052] That is, when the liquid crystal polyester has monomer units (I), monomer units (II) and monomer units (III), the number of monomer units (I) relative to the total number of monomer units of the liquid crystal polyester can be, for example, 30 mol% or more and 80 mol% or less, 30 mol% or more and 70 mol% or less, 40 mol% or more and 80 mol% or less, 40 mol% or more and 70 mol% or less, 45 mol% or more and 80 mol% or less, 45 mol% or more and 70 mol% or less, 50 mol% or more and 80 mol% or less, 50 mol% or more and 70 mol% or less, 55 mol% or more and 80 mol% or less, or 55 mol% or more and 70 mol% or less.

[0053] When the liquid crystal polyester has monomer units (I), monomer units (II), and monomer units (III), the number of monomer units (II) relative to the total number of monomer units in the liquid crystal polyester can be, for example, 35 mol% or less, or 30 mol% or less. Furthermore, when the liquid crystal polyester has monomer units (I), monomer units (II), and monomer units (III), the number of monomer units (II) relative to the total number of monomer units in the liquid crystal polyester can be, for example, 5 mol% or more, 10 mol% or more, or 15 mol% or more.

[0054] That is, when the liquid crystal polyester has monomer units (I), monomer units (II) and monomer units (III), the number of monomer units (II) relative to the total number of monomer units of the liquid crystal polyester can be, for example, 5 mol% or more and 35 mol% or less, 5 mol% or more and 30 mol% or less, 10 mol% or more and 35 mol% or less, 10 mol% or more and 30 mol% or less, 15 mol% or more and 35 mol% or less, or 15 mol% or more and 30 mol% or less.

[0055] When the liquid crystal polyester has monomer units (I), monomer units (II), and monomer units (III), the number of monomer units (III) relative to the total number of monomer units in the liquid crystal polyester can be, for example, 35 mol% or less, or 30 mol% or less. Furthermore, when the liquid crystal polyester has monomer units (I), monomer units (II), and monomer units (III), the number of monomer units (III) relative to the total number of monomer units in the liquid crystal polyester can be, for example, 5 mol% or more, 10 mol% or more, or 15 mol% or more.

[0056] That is, when the liquid crystal polyester has monomer units (I), monomer units (II) and monomer units (III), the number of monomer units (III) relative to the total number of monomer units of the liquid crystal polyester can be, for example, 5 mol% or more and 35 mol% or less, 5 mol% or more and 30 mol% or less, 10 mol% or more and 35 mol% or less, 10 mol% or more and 30 mol% or less, 15 mol% or more and 35 mol% or less, or 15 mol% or more and 30 mol% or less.

[0057] When the liquid crystal polyester has monomer units (I), monomer units (II) and monomer units (III), the ratio of the number of monomer units (II) to the number of monomer units (III) ([number of monomer units (II)] / [number of monomer units (III)]) can be 0.9 / 1 to 1 / 0.9, 0.95 / 1 to 1 / 0.95, or 0.98 / 1 to 1 / 0.98.

[0058] The liquid crystal polyester may also have monomer units other than monomer units (I), monomer units (II) and monomer units (III), but the number of such monomer units relative to the total number of monomer units of the liquid crystal polyester is preferably 10% or less, more preferably 5% or less, even more preferably 2% or less, even more preferably 1% or less, and particularly preferably 0%.

[0059] In this specification, the number of each monomer unit in the liquid crystal polyester is determined using the analytical method described in Japanese Patent Application Publication No. 2000-19168. Specifically, by reacting the liquid crystal polyester with a lower alcohol in a supercritical state to depolymerize it, and by quantifying the depolymerization products (monomers from which each monomer unit is derived) using liquid chromatography, the number of each monomer unit relative to all monomer units can be calculated.

[0060] Liquid crystal polyesters can be manufactured by polymerizing raw material monomers corresponding to the monomer units constituting them. For example, they can be manufactured according to the method described in Japanese Patent No. 6439027.

[0061] The content of liquid crystal polyester, based on the total amount of the liquid crystal polyester composition, can be, for example, 60% or more by mass, 70% or more by mass, or 80% or more by mass. Furthermore, the content of liquid crystal polyester, based on the total amount of the liquid crystal polyester composition, can be, for example, 95% or less by mass, 90% or less by mass, or 88% or less by mass. That is, the content of liquid crystal polyester, based on the total amount of the liquid crystal polyester composition, can be, for example, 60% or more and 95% or less by mass, 60% or more and 90% or less by mass, 60% or more and 88% or less by mass, 70% or more and 95% or less by mass, 70% or more and 90% or less by mass, 70% or more and 88% or less by mass, 80% or more and 95% or less by mass, 80% or more and 90% or less by mass, or 80% or more and 88% or less by mass.

[0062] (2) Fibrous filler The liquid crystal polyester composition contains a fibrous filler (A).

[0063] Examples of fibrous fillers (A) include glass fibers and carbon fibers, among which glass fibers are preferred. The proportion of glass fibers in the fibrous filler (A) can be, for example, 90% by mass or more, 95% by mass or more, 99% by mass or more, or 100% by mass.

[0064] The proportion of fibrous filler (A-1) with a fiber length of less than 50 μm in the fibrous filler (A) is less than 0.5% by mass, or less than 0.3% by mass, less than 0.1% by mass, or less than 0.05% by mass.

[0065] The proportion of fibrous filler (A-1) with a fiber length of less than 50 μm in the fibrous filler (A) can also be 0% by mass. In addition, the fibrous filler (A) may contain a small amount of fibrous filler (A-1) with a fiber length of less than 50 μm. In this case, the proportion of fibrous filler (A-1) can be, for example, more than 0.001% by mass, more than 0.005% by mass, or more than 0.01% by mass.

[0066] The proportion of fibrous filler (A-2) with a fiber length of 10 μm or more and 75 μm or less in the fibrous filler (A) can be, for example, 0% or more by mass, 0.001% or more by mass, or 0.005% or more by mass. Therefore, there is a tendency for fibrous filler to exhibit a more effective reinforcing effect.

[0067] Furthermore, the proportion of fibrous filler (A-2) with a fiber length of 10 μm or more and 75 μm or less in the fibrous filler (A) can be, for example, 2.0% by mass or less, 1.0% by mass or less, 0.5% by mass or less, 0.3% by mass or less, or 0.1% by mass or less. As a result, there is a tendency for the mechanical strength of the molded article to become higher.

[0068] The number-average fiber length of the fibrous filler (A) can be, for example, 50 μm or more, 100 μm or more, or 200 μm or more. As a result, there is a tendency for the mechanical strength of the molded product to become higher.

[0069] Furthermore, the number-average fiber length of the fibrous filler (A) can be, for example, less than 1500 μm, less than 1000 μm, or more than 500 μm. There is a tendency for improved detail filling properties in the molded product.

[0070] The fiber length distribution of the fibrous packing (A) (the proportion of fibrous packing (A-1), the proportion of fibrous packing (A-2), and the number-average fiber length) was determined by the following methods.

[0071] <Determination of fiber length distribution> 4g of a liquid crystal polyester composition was heated at 600°C for 4 hours to obtain ash. The obtained ash was dispersed in ethylene glycol to prepare a microscopic specimen, which was observed using an optical microscope at a field of view of 500x. The fiber lengths of fibers with a length greater than the fiber diameter in the fibers contained within the field of view (i.e., fibers with both ends located within the field of view) were measured. The fiber lengths of more than 500 fibers were measured to determine the fiber length distribution.

[0072] The fiber diameter (single fiber diameter) of the fibrous packing (A) can be, for example, 5 μm or more, 6 μm or more, or 9 μm or more. Furthermore, the fiber diameter (single fiber diameter) of the fibrous packing (A) can be, for example, 17 μm or less, 15 μm or less, or 12 μm or less. That is, the fiber diameter (single fiber diameter) of the fibrous packing (A) can be, for example, 5 μm or more and 17 μm or less, 5 μm or more and 15 μm or less, 5 μm or more and 12 μm or less, 6 μm or more and 17 μm or less, 6 μm or more and 15 μm or less, 6 μm or more and 12 μm or less, 9 μm or more and 17 μm or less, 9 μm or more and 15 μm or less, or 9 μm or more and 12 μm or less.

[0073] The content of fibrous filler (A), based on the total amount of the liquid crystal polyester composition, can be, for example, 5% by mass or more, 10% by mass or more, or 12% by mass or more. Furthermore, the content of fibrous filler (A), based on the total amount of the liquid crystal polyester composition, can be, for example, 40% by mass or less, 30% by mass or less, or 20% by mass or less. That is, the content of fibrous filler (A), based on the total amount of the liquid crystal polyester composition, can be, for example, 5% by mass and less than 40% by mass, 5% by mass and less than 30% by mass, 5% by mass and less than 20% by mass, 10% by mass and less than 40% by mass, 10% by mass and less than 30% by mass, 10% by mass and less than 20% by mass, 12% by mass and less than 40% by mass, 12% by mass and less than 30% by mass, or 12% by mass and less than 20% by mass.

[0074] The liquid crystal polyester composition may contain one or more resins other than liquid crystal polyesters. Examples of such resins include polyolefins, cyclic polyolefins, polyvinyl chloride, polysulfone, (meth)acrylic resins, polyphenylene ether resins, polyacetal resins, polyamide resins, imide resins, polystyrene resins, cellulose resins, polyetheretherketone resins, fluoropolymers, polycarbonate resins, and thermosetting resins.

[0075] The liquid crystal polyester composition may contain one or more additives other than fibrous fillers. Examples of such additives include fillers, colorants, dispersants, plasticizers, antioxidants, curing agents, flame retardants, heat stabilizers, ultraviolet absorbers, antistatic agents, surfactants, lubricants, and release agents.

[0076] The liquid crystal polyester composition can be in the form of powder, granules (e.g., pellets, granules, etc.), film, sheet, plate, etc.

[0077] The liquid crystal polyester composition of this embodiment can be manufactured, for example, by the following method.

[0078] (Method for manufacturing liquid crystal polyester composition) The method for manufacturing the liquid crystal polyester composition of this embodiment may include a mixing step of mixing liquid crystal polyester with fibrous filler (hereinafter also referred to as fibrous filler (a)) to obtain a liquid crystal polyester composition.

[0079] In the mixing process, the liquid crystal polyester and the fibrous filler (a) are mixed in such a way that the proportion of the fibrous filler (A-1) with a fiber length of less than 50 μm in the liquid crystal polyester composition in the fibrous filler (A) is less than 0.5% by mass.

[0080] The fibrous filler (a) can be, for example, a fiber bundle obtained by bundling fibrous fillers with a bundling agent.

[0081] In the mixing process, the fibrous filler in the liquid crystal polyester is broken, forming short-fiber fibrous fillers. If the fibrous filler is not broken but broken, significantly shorter fibrous fillers (A-1) are easily formed. Therefore, by selecting a mixing method that minimizes the breakage of the fibrous filler in the mixing process, it is easy to obtain a liquid crystal polyester composition with a fibrous filler (A-1) proportion of 0.5% by mass or less.

[0082] As a mixing method in the mixing process, one example is the method of adding fibrous filler (a) to the melt of liquid crystal polyester and then mixing it. In such a method, for example, by extending the time from adding the fibrous filler (a) to the melt of liquid crystal polyester until mixing (e.g., extending the length from the inlet of the fibrous filler (a) to the kneading plate), there is a tendency to reduce the breakage of the fibrous filler. By extending the time from adding the fibrous filler (a) to mixing, the fibrous filler (a) disintegrates in the melt, and the formation of fibrous filler (A-1) caused by the breakage of the aggregates of fibrous filler (a) (e.g., fiber bundles bonded with a slugging agent) can be suppressed.

[0083] The mixing process can be implemented, for example, using a twin-screw extruder.

[0084] The liquid crystal polyester composition of this embodiment can be in the form of granules (e.g., particles, pellets, etc.), films, sheets, plates, etc. That is, the above-mentioned mixing process can also be a process of mixing liquid crystal polyester with fibrous filler (hereinafter also referred to as fibrous filler (a)) and molding it to obtain a molded article of liquid crystal polyester composition.

[0085] The liquid crystal polyester composition of this embodiment can be suitably applied to components in communication equipment, electrical equipment, electronic equipment, medical equipment, automobiles, home appliances, industrial machinery, and daily necessities. These components can be manufactured, for example, by molding the liquid crystal polyester composition using injection molding, compression molding, extrusion molding, blow molding, or other methods.

[0086] The above describes one embodiment of the invention disclosed herein, but the invention disclosed herein is not limited to the above embodiment.

[0087] Example The following examples illustrate the invention disclosed herein, but the invention disclosed herein is not limited to these examples. In the examples, unless otherwise specified, the percentages and parts representing the content or amount used are mass standards.

[0088] (Example 1) (1) Manufacturing of liquid crystal polyester 1118.8 g (8.10 mol) of p-hydroxybenzoic acid, 547.4 g (3.00 mol) of 2-hydroxy-6-naphthoic acid, 1235.3 g (12.1 mol) of acetic anhydride, and 0.17 g of 1-methylimidazole were added to a reactor equipped with a stirrer, torque meter, nitrogen inlet pipe, thermometer, and reflux cooler. After thoroughly purging the reactor with nitrogen, the temperature was raised to 140°C over a nitrogen flow for 15 minutes, maintained at 140°C, and refluxed for 1 hour. Then, while distilling off the distillate byproduct acetic acid, the temperature was raised to 280°C over 3 hours and 40 minutes. The reaction was considered complete when the torque increased, and the contents were removed. The flow initiation temperature of the obtained solid component was 235°C. The obtained solid component was cooled to room temperature, pulverized using a coarse pulverizer, and then heated from room temperature (25°C) to 235°C over 1 hour under a nitrogen atmosphere, followed by a further heating from 235°C to 240°C over 4 hours and 10 minutes. Solid-state polymerization was then carried out at 240°C for 5 hours. The resulting solid polymer was cooled to room temperature to obtain a powdered liquid crystal polyester (1). The flow initiation temperature of the obtained liquid crystal polyester (1) was 277°C.

[0089] (2) Manufacturing of liquid crystal polyester composition Using a twin-screw extruder (Shibaura Machinery, TEM48S), liquid crystal polyester (1) was compounded with glass fiber to produce granules of the liquid crystal polyester composition.

[0090] Specifically, liquid crystal polyester (1) is supplied from the main feed port of a twin-screw extruder, and glass fiber is supplied from the side feed port. The mixture is then compounded and extruded from the nozzle of the extruder to obtain filaments. It should be noted that, regarding the supply amount, the glass fiber is set to 15 parts by mass relative to 85 parts by mass of liquid crystal polyester (1).

[0091] The strands are cooled by spraying water to solidify them, then air is blown to remove the water and further cooled. The solidified strands are then cut using a granulator to obtain granules of the liquid crystal polyester composition.

[0092] (Comparative Example 1) The position of the side feed inlet is moved to the downstream side, and the length from the side feed inlet to the kneading disc is set to 0.9 times that of Example 1, and the length of the kneading disc is set to 0.5 times that of Example 1. Otherwise, the same operation is performed as in Example 1 to obtain granules of the liquid crystal polyester composition.

[0093] <Determination of fiber length distribution of glass fiber> For the granules of the liquid crystal polyester compositions obtained in Example 1 and Comparative Example 1, the fiber length distribution of the glass fibers was determined by the following method.

[0094] 4g of granules were heated at 600℃ for 4 hours to obtain ash. The obtained ash was dispersed in ethylene glycol to prepare a microscopic specimen, which was observed using an optical microscope at a field of view of 500x. The fiber lengths of fibers with a length greater than the fiber diameter within the field of view were measured. The fiber lengths of more than 500 fibers were measured to determine the fiber length distribution.

[0095] Based on the obtained fiber length distribution, the proportion of fibrous fillers with a fiber length of less than 50 μm (A-1), the proportion of fibrous fillers with a fiber length of more than 10 μm and less than 75 μm (A-2), and the number-average fiber length of the fibrous fillers were determined. The results are shown in Table 1.

[0096] <Evaluation of gas production> The amount of gas generated was evaluated for the granules of the liquid crystal polyester compositions obtained in Example 1 and Comparative Example 1 by the following method.

[0097] Using granules, dumbbell-shaped test pieces with a thickness of 0.8 mm were injection molded. The parallel portion of these test pieces was then cut into 5 mm squares to obtain test samples of 5 mm × 5 mm × 0.8 mm. 4 g of the test sample was sealed in a vial using a separatory membrane. After heating the sample in the vial at 120°C for 20 hours, the amount of gas produced was determined by headspace gas chromatography (GC-2030AF, Shimadzu Corporation) under the following conditions.

[0098] <Conditions> Column: Restek Rtx-1301 (inner diameter: 0.25 mm, length: 60 m, film thickness: 1.4 μm) Column temperature: Hold at 60°C for 5 minutes, then increase to 220°C at a rate of 10°C / min, and hold at 220°C for 15 minutes. Carrier gas: Helium Flow split ratio: 10 Carrier gas flow rate: 10 mL / min A standard curve was used to quantify acetone, acetic acid, phenol, and phenol acetate. For peaks from other sources, components with a retention time of less than 15.5 minutes were converted to acetone for quantification, and components with a retention time exceeding 15.5 minutes were converted to phenol for quantification. The measured quantities of low-boiling-point components with a retention time of less than 15.5 minutes and high-boiling-point components with a retention time exceeding 15.5 minutes are shown in Table 2.

[0099] As shown in Table 2, the liquid crystal polyester composition of Example 1, compared with the liquid crystal polyester composition of Comparative Example 1, suppressed the generation of gases (especially high-boiling-point components) under high-temperature conditions.

Claims

1. A liquid crystalline polyester composition comprising a liquid crystalline polyester and a fibrous filler (A), the proportion of fibrous filler (A-I) having a fiber length of 50 μm or less in the fibrous filler (A) is 0.5 mass% or less.

2. The liquid crystalline polyester composition according to claim 1, wherein, the proportion of fibrous filler (A-2) having a fiber length of 10 μm or more and 75 μm or less in the fibrous filler (A) is 2.0 mass% or less.

3. The liquid crystalline polyester composition of claim 1, wherein, the fibrous filler (A) comprises glass fibers.

4. The liquid crystalline polyester composition of claim 1, wherein, the content of the fibrous filler (A) is 5 mass% or more and 40 mass% or less.

5. The liquid crystalline polyester composition of claim 1, wherein, the liquid crystalline polyester contains a monomer unit derived from an aromatic hydroxy carboxylic acid.

6. The liquid crystalline polyester composition according to claim 5, wherein, the content of the monomer unit is 50 mol% or more relative to the total of all monomer units constituting the liquid crystalline polyester.

7. A production method of a liquid crystalline polyester composition, comprising a mixing step of mixing a liquid crystalline polyester and a fibrous filler to obtain a liquid crystalline polyester composition, the mixing step is a step of mixing the liquid crystalline polyester and the fibrous filler in such a manner that the proportion of fibrous filler (A-I) having a fiber length of 50 μm or less in the fibrous filler (A) in the liquid crystalline polyester composition becomes 0.5 mass% or less.

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