Resin composition and molded article

Abstract

To provide a resin composition for further enhancing slidability, and a molding manufactured using the resin composition.SOLUTION: A resin composition contains a liquid crystal polyester resin, and a fluorine resin, wherein the fluorine resin has an average particle diameter determined by image analysis of an SEM image of the fluorine resin of 20 μm or less, and the fluorine resin exhibits a first endothermic peak temperature of 328°C or higher and a second endothermic peak temperature of 325°C or lower when an endothermic peak when the temperature is raised at a rate of 1°C / min is measured using a differential scanning calorimeter.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition and a molded article produced using the resin composition. [Background technology]

[0002] Liquid crystal polyester resins are known to have high fluidity, heat resistance, and dimensional accuracy, and are used in a variety of fields, including electrical, electronic, mechanical, optical equipment, automobiles, aircraft, and medical fields. It is also known that a resin composition in which a fluororesin such as polytetrafluoroethylene is added to a liquid crystal polyester resin has improved mold releasability during molding and improved friction and wear resistance. For example, Patent Document 1 discloses a liquid crystal polyester resin composition containing 0.2 to 50 parts by weight of a low-molecular-weight fluorocarbon polymer having a flow initiation temperature of 350° C. or less, per 100 parts by weight of the liquid crystal polyester resin. It is disclosed that this liquid crystal polyester resin composition has excellent dispersibility, particularly the dispersibility of the fluororesin component, and that resin molded articles using the resin composition have good appearance, mechanical strength, and sliding properties. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-26699 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, the use of molded articles using liquid crystal polyester resins has been increasing in the field of transportation equipment, including automobiles and aircraft. For application in such fields, liquid crystal polyester resin compositions with higher slidability are required. The conventional liquid crystal polyester resin composition described in Patent Document 1 is not sufficient for the required level of sliding properties.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resin composition that can further improve sliding properties and a molded article produced using the resin composition. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention employs the following configuration. [1] A resin composition comprising a liquid crystalline polyester resin and a fluororesin, wherein the fluororesin has an average particle size of 20 μm or less as determined by image analysis of an SEM image of the fluororesin, and the fluororesin exhibits a first endothermic peak temperature of 328°C or higher and a second endothermic peak temperature of 325°C or lower when measuring endothermic peaks at a temperature increase rate of 1°C / min using a differential scanning calorimeter. [2] The resin composition according to [1], wherein the first endothermic peak temperature is 328°C or higher and 333°C or lower, and the second endothermic peak temperature is 320°C or higher and 325°C or lower. [3] The resin composition according to [1] or [2], wherein the fluororesin comprises a first fluororesin exhibiting the first endothermic peak temperature and a second fluororesin exhibiting the second endothermic peak temperature. [4] The resin composition according to any one of [1] to [3], wherein the liquid crystal polyester resin contains a repeating unit having a 2,6-naphthylene group. [5] The resin composition according to any one of [1] to [4], further comprising a filler. [6] The resin composition according to any one of [1] to [5], wherein the content of the liquid crystal polyester resin is 70 to 98 mass% based on the total amount of the resin composition, and the content of the fluororesin is 2 to 30 mass% based on the total amount of the resin composition. [7] A molded article produced using the resin composition according to any one of [1] to [6]. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a resin composition that can further improve slidability and a molded article produced using the resin composition. [Brief explanation of the drawings]

[0008] [Figure 1] 1 shows the measurement results of the endothermic peak of the fluororesin in the pellet-shaped resin composition of Example 1. [Figure 2] 1 is an SEM image of a cross section of the pellet-shaped resin composition of Example 1. [Figure 3] 1 is an SEM image of a cross section of the pellet-shaped resin composition of Comparative Example 1. [Figure 4] 1 is an SEM image of a cross section of a pellet-shaped resin composition of Comparative Example 2. [Figure 5] 10 is an SEM image of a cross section of the pellet-shaped resin composition of Comparative Example 5. [Figure 6] 1 is an SEM image of a cross section of a pellet-shaped resin composition of Comparative Example 6. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Resin composition) The resin composition of the present embodiment contains a liquid crystal polyester resin and a fluororesin, and the fluororesin has an average particle size of 20 μm or less as determined by image analysis of an SEM image of the fluororesin. When the endothermic peaks of the fluororesin are measured using a differential scanning calorimeter while being heated at a rate of 1°C / min, the fluororesin exhibits a first endothermic peak temperature of 328°C or higher and a second endothermic peak temperature of 325°C or lower.

[0010] In this specification, the term "resin composition" refers to a powder mixture obtained by mixing a liquid crystal polyester resin, a fluororesin, and, if necessary, other components, or a melt obtained by melt-kneading the powder mixture. Typically, it is a melt, and a specific shape thereof is, for example, pellets.

[0011] [Average particle size of fluororesin in resin composition] The average particle size of the fluororesin in the resin composition of this embodiment can be determined by image analysis of an SEM image. For example, when the resin composition of this embodiment is in the form of pellets, the pellets are subjected to cross-section processing of the pellet-shaped resin composition using a cross-section specimen preparation device (manufactured by JEOL Ltd., "Cross Section Polisher SM-09010") at an acceleration voltage of 4.5 kV for 20 hours. Next, a cross-sectional image of the pellet-shaped resin composition is taken using a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, "S-4800") at an acceleration voltage of 10 kV. The cross-sectional image is taken using an attached YAG backscattered electron detector at an observation magnification of 500x. Next, the average particle size of the fluororesin in the resin composition is determined using image analysis software (manufactured by Mitani Shoji Co., Ltd., "WinROOF" Ver. 3.54) by the following analysis method.

[0012] ≪Analysis method≫ The obtained cross-sectional image is subjected to median processing with a filter size of 5 × 5, and then binarized into regions containing liquid crystal polyester resin and regions containing fluororesin. The threshold value for the binarization process is set to a value that allows visual inspection of the image and distinguishes between the fluororesin and other components. For example, the threshold value for the binarization process is set to 100 to 130. After removing noise and regions cut off at the image edge using the processed image, the circle-equivalent diameters of 150 fluororesin regions are measured. The average of the obtained measurements is calculated and used as the average particle diameter of the fluororesin in the resin composition.

[0013] The average particle size of the fluororesin in the resin composition of this embodiment is 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less, and even more preferably 8 μm or less.

[0014] When the average particle size of the fluororesin in the resin composition of this embodiment is 20 μm or less, the fluororesin is well dispersed in the resin composition, and therefore the sliding properties of a molded article produced using the resin composition are good. Furthermore, when the average particle size of the fluororesin in the resin composition is not more than the above-mentioned preferable upper limit, the sliding properties are further improved.

[0015] The lower limit of the average particle size of the fluororesin in the resin composition of this embodiment is not particularly limited, and is, for example, 0.1 μm or more.

[0016] The average particle size of the fluororesin in the resin composition of this embodiment can be adjusted, for example, by the type of liquid crystal polyester resin used in combination, the type of fluororesin, the content ratio of the liquid crystal polyester resin and the fluororesin, etc. It can also be adjusted by adding a filler described below to improve shear during melt-kneading. It can also be adjusted by the production conditions for producing pellets and molded articles.

[0017] [Endothermic peak temperature of fluororesin in resin composition] When the fluororesin in the resin composition of this embodiment is measured for endothermic peaks using a differential scanning calorimeter (for example, manufactured by Shimadzu Corporation, product name "DSC-50") while heating at a rate of 1°C / min, the fluororesin shows a first endothermic peak temperature of 328°C or higher and a second endothermic peak temperature of 325°C or lower.

[0018] Here, the endothermic peak measured by a differential scanning calorimeter indicates the endothermic heat (melting point) due to the melting of the fluororesin. Since the melting point is greatly affected by the molecular weight, it is understood that when the resin composition of the present embodiment contains the same type of fluororesin, fluororesins with different molecular weights are contained.

[0019] The fluororesin in the resin composition of the present embodiment is a fluororesin that exhibits the first endothermic peak temperature, i.e., a fluororesin with a higher molecular weight, which can further improve the durability of a molded article produced using the resin composition. Furthermore, by using a fluororesin that exhibits the second endothermic peak temperature, i.e., a fluororesin with a lower molecular weight, the dispersibility of the fluororesin in a molded article produced using the resin composition can be further improved.

[0020] The endothermic peak of the fluororesin in the resin composition can be measured by decomposing resins other than the fluororesin and extracting only the fluororesin. For example, when the resin composition of the present embodiment is a resin composition comprising a liquid crystal polyester resin and a fluororesin, the endothermic peak can be measured by decomposing the liquid crystal polyester resin with an amine and extracting only the fluororesin.

[0021] The first endothermic peak temperature of the fluororesin in the resin composition of this embodiment is preferably 328°C or higher and 350°C or lower, more preferably 328°C or higher and 340°C or lower, and even more preferably 328°C or higher and 333°C or lower.

[0022] The second endothermic peak temperature of the fluororesin in the resin composition of this embodiment is preferably 300°C or higher and 325°C or lower, more preferably 310°C or higher and 325°C or lower, and even more preferably 320°C or higher and 325°C or lower.

[0023] When the first endothermic peak temperature and the second endothermic peak temperature of the fluororesin in the resin composition of the present embodiment are within the above-mentioned preferred ranges, a synergistic effect (improvement of sliding properties by achieving both dispersibility and durability) can be more easily obtained by using in combination a fluororesin showing the first endothermic peak temperature and a fluororesin showing the second endothermic peak temperature.

[0024] The first endothermic peak temperature and the second endothermic peak temperature of the fluororesin in the resin composition of the present embodiment can be adjusted, for example, by the type and structure of the fluororesin, typically by including a plurality of fluororesins having different specific molecular weights.

[0025] The fluororesin in the resin composition of this embodiment is sufficient as long as it exhibits at least a first endothermic peak temperature of 328°C or higher and a second endothermic peak temperature of 325°C or lower, and may also exhibit other endothermic peak temperatures.

[0026] <Liquid Crystal Polyester Resin> The liquid crystal polyester resin of the present embodiment is not particularly limited as long as it is a polyester resin that exhibits liquid crystallinity in a molten state. The liquid crystal polyester resin of the present embodiment may be a liquid crystal polyester amide, a liquid crystal polyester ether, a liquid crystal polyester carbonate, a liquid crystal polyester imide, or the like.

[0027] The flow initiation temperature of the liquid crystal polyester resin of the present embodiment is preferably 250°C or higher, more preferably 270°C or higher, and even more preferably 290°C or higher. The flow starting temperature of the liquid crystal polyester resin of the present embodiment is preferably 400° C. or lower, more preferably 360° C. or lower, and even more preferably 330° C. or lower.

[0028] For example, the flow starting temperature of the liquid crystal polyester resin of this embodiment is preferably 250°C or higher and 400°C or lower, more preferably 270°C or higher and 360°C or lower, and even more preferably 290°C or higher and 330°C or lower.

[0029] When the flow starting temperature of the liquid crystal polyester resin of the present embodiment is within the above-mentioned preferred range, the dispersibility of the fluororesin used in combination is further improved.

[0030] In this specification, the flow initiation temperature is also called the flow temperature or the flow temperature, and is a temperature that is an indicator of the molecular weight of a liquid crystal polyester resin (see "Liquid Crystal Polymer - Synthesis, Molding, and Applications" edited by Naoyuki Koide, CMC Co., Ltd., June 5, 1987, p. 95).

[0031] Specifically, the flow initiation temperature was measured by using a capillary rheometer to measure the liquid crystal polyester resin at 9.8 MPa (100 kg / cm 2 ) while heating at a rate of 4°C / min under a load of 1000 kJ / s and extruding from a nozzle with an inner diameter of 1 mm and a length of 10 mm, this is the temperature at which the viscosity is 4800 Pa·s (48,000 poise).

[0032] The liquid crystal polyester resin of the present embodiment is preferably a wholly aromatic liquid crystal polyester obtained by using only aromatic compounds as raw material monomers.

[0033] Typical examples of the liquid crystal polyester resin of this embodiment include those obtained by polymerizing (polycondensing) an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid, and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine; those obtained by polymerizing multiple types of aromatic hydroxycarboxylic acids; those obtained by polymerizing an aromatic dicarboxylic acid and at least one compound selected from the group consisting of an aromatic diol, an aromatic hydroxyamine, and an aromatic diamine; and those obtained by polymerizing a polyester such as polyethylene terephthalate and an aromatic hydroxycarboxylic acid. Here, the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, aromatic diol, aromatic hydroxyamine and aromatic diamine may each independently be replaced in part or in whole by a polymerizable derivative thereof.

[0034] Examples of polymerizable derivatives of compounds having a carboxyl group, such as aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids, include those obtained by converting a carboxyl group to an alkoxycarbonyl group or an aryloxycarbonyl group (esters); those obtained by converting a carboxyl group to a haloformyl group (acid halides); and those obtained by converting a carboxyl group to an acyloxycarbonyl group (acid anhydrides).

[0035] Examples of polymerizable derivatives of compounds having a hydroxyl group, such as aromatic hydroxycarboxylic acids, aromatic diols, and aromatic hydroxyamines, include those obtained by acylation of the hydroxyl group to convert it into an acyloxyl group (acylated products). Examples of polymerizable derivatives of compounds having an amino group, such as aromatic hydroxyamines and aromatic diamines, include those obtained by acylation of the amino group to convert it into an acylamino group (acylated product).

[0036] Of the above, the liquid crystal polyester resin used in this embodiment preferably contains a repeating unit having a 2,6-naphthylene group, from the viewpoint of further improving the dispersibility of the fluororesin. When the liquid crystal polyester resin used in this embodiment contains a repeating unit having a 2,6-naphthylene group, the content of the repeating unit having a 2,6-naphthylene group is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more, based on the total amount of all repeating units in the liquid crystal polyester resin. The content of repeating units having a 2,6-naphthylene group is preferably 90 mol % or less, more preferably 85 mol % or less, and even more preferably 80 mol % or less, based on the total amount of all repeating units in the liquid crystal polyester resin.

[0037] For example, the content of repeating units having a 2,6-naphthylene group is preferably 40 mol% or more and 90 mol% or less, more preferably 50 mol% or more and 85 mol% or less, and even more preferably 60 mol% or more and 80 mol% or less, relative to the total amount of all repeating units in the liquid crystal polyester resin.

[0038] The liquid crystal polyester resin of this embodiment preferably has a repeating unit represented by the following formula (1) (hereinafter also referred to as "repeating unit (1)"), and more preferably has a repeating unit (1), a repeating unit represented by the following formula (2) (hereinafter also referred to as "repeating unit (2)"), and a repeating unit represented by the following formula (3) (hereinafter also referred to as "repeating unit (3)").

[0039] (1)-O-Ar 1 -CO- (2)-CO-Ar 2 -CO- (3)-X-Ar 3 -Y- [In the formula, Ar 1 represents a phenylene group, a naphthylene group, or a biphenylylene group. 2 and Ar 3each independently represents a phenylene group, a naphthylene group, a biphenylylene group, or a group represented by the following formula (4): X and Y each independently represent an oxygen atom or an imino group (—NH—). Ar 1 , Ar 2 or Ar 3 Each hydrogen atom in the group represented by the formula (I) may be independently substituted with a halogen atom, an alkyl group, or an aryl group.

[0040] (4)-Ar 4 -Z-Ar 5 - [In the formula, Ar 4 and Ar 5 each independently represents a phenylene group or a naphthylene group; Z represents an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, or an alkylidene group.

[0041] Ar 1 , Ar 2 or Ar 3 Examples of halogen atoms that can substitute for one or more hydrogen atoms in the group represented by the formula include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0042] Ar 1 , Ar 2 or Ar 3 Examples of the alkyl group that can substitute one or more hydrogen atoms in the group represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, a t-butyl group, an n-hexyl group, a 2-ethylhexyl group, an n-octyl group, and an n-decyl group, and the number of carbon atoms is preferably 1 to 10.

[0043] Ar 1 , Ar 2 or Ar 3 Examples of the aryl group that can substitute one or more hydrogen atoms in the group represented by the formula (I) include a phenyl group, an o-tolyl group, an m-tolyl group, a p-tolyl group, a 1-naphthyl group, and a 2-naphthyl group, and the number of carbon atoms therein is preferably 6 to 20.

[0044] Ar 1 , Ar 2 or Ar 3 When a hydrogen atom in the group represented by the formula (I) is substituted with the above-mentioned group, the number of substitutions is preferably one or two, and more preferably one.

[0045] Examples of the alkylidene group for Z in formula (4) include a methylene group, an ethylidene group, an isopropylidene group, an n-butylidene group, and a 2-ethylhexylidene group, and the number of carbon atoms is preferably 1 to 10.

[0046] The repeating unit (1) is a repeating unit derived from a specific aromatic hydroxycarboxylic acid. 1 is a 1,4-phenylene group (a repeating unit derived from p-hydroxybenzoic acid), and Ar 1 is a 2,6-naphthylene group (a repeating unit derived from 6-hydroxy-2-naphthoic acid) is preferred.

[0047] In this specification, the term "derived from" means that the chemical structure of the functional group that contributes to the polymerization changes as the raw material monomer is polymerized, and no other structural changes occur.

[0048] The repeating unit (2) is a repeating unit derived from a specific aromatic dicarboxylic acid. 2 is a 1,4-phenylene group (a repeating unit derived from terephthalic acid), Ar 2 is a 1,3-phenylene group (a repeating unit derived from isophthalic acid), Ar 2 is a 2,6-naphthylene group (a repeating unit derived from 2,6-naphthalenedicarboxylic acid), and Ar 2 is preferably a diphenylether-4,4'-diyl group (a repeating unit derived from diphenylether-4,4'-dicarboxylic acid), and Ar 2 is a 1,4-phenylene group, Ar 2 is a 1,3-phenylene group, and Ar 2is more preferably a 2,6-naphthylene group.

[0049] The repeating unit (3) is a repeating unit derived from a specific aromatic diol, aromatic hydroxylamine, or aromatic diamine. 3 is a 1,4-phenylene group (repeating units derived from hydroquinone, p-aminophenol or p-phenylenediamine), and Ar 3 is a 4,4'-biphenylylene group (a repeating unit derived from 4,4'-dihydroxybiphenyl, 4-amino-4'-hydroxybiphenyl or 4,4'-diaminobiphenyl).

[0050] The content of the repeating unit (1) is preferably 30 mol% or more and 80 mol% or less, more preferably 40 mol% or more and 70 mol% or less, and even more preferably 45 mol% or more and 70 mol% or less, of the total amount of all repeating units (the value obtained by dividing the mass of each repeating unit constituting the liquid crystal polyester resin by the formula weight of each repeating unit to determine the substance equivalent (mol) of each repeating unit, and then adding these values ​​up).

[0051] The content of repeating unit (2) is preferably 35 mol % or less, more preferably 10 mol % to 35 mol %, and even more preferably 15 mol % to 30 mol %, based on the total amount of all repeating units.

[0052] The content of repeating unit (3) is preferably 35 mol % or less, more preferably 10 mol % to 35 mol %, and even more preferably 15 mol % to 30 mol %, based on the total amount of all repeating units.

[0053] The ratio of the content of repeating unit (2) to the content of repeating unit (3), expressed as [content of repeating unit (2)] / [content of repeating unit (3)] (mol / mol), is preferably 0.9 / 1 to 1 / 0.9, more preferably 0.95 / 1 to 1 / 0.95, and even more preferably 0.98 / 1 to 1 / 0.98.

[0054] The liquid crystal polyester resin of this embodiment may have two or more types of each of the repeating units (1) to (3). The liquid crystal polyester resin may also have a repeating unit other than the repeating units (1) to (3), and the content thereof is preferably 10 mol % or less, more preferably 5 mol % or less, based on the total amount of all repeating units.

[0055] The liquid crystal polyester resin of the present embodiment preferably has a repeating unit (3) in which X and Y are each an oxygen atom, i.e., a repeating unit derived from a specific aromatic diol, because this tends to reduce the melt viscosity. It is more preferable that the liquid crystal polyester resin of the present embodiment has only repeating units (3) in which X and Y are each an oxygen atom.

[0056] The liquid crystal polyester resin of the present embodiment may be used alone or in combination of two or more kinds, but is preferably used in combination of two or more kinds. Specifically, it is preferable to use a liquid crystal polyester resin A (hereinafter referred to as "LCPA") containing a repeating unit having a 2,6-naphthylene group in combination with a liquid crystal polyester resin B (hereinafter referred to as "LCPB") not containing a repeating unit having a 2,6-naphthylene group. Among these, the LCPA is more preferably a liquid crystal polyester resin having the repeating unit (1), repeating unit (2), and repeating unit (3), in which any one of the repeating units (1) to (3) has a 2,6-naphthylene group. Furthermore, the LCPB is more preferably a liquid crystal polyester resin having the repeating unit (1), repeating unit (2), and repeating unit (3), in which none of the repeating units (1) to (3) has a 2,6-naphthylene group.

[0057] When the liquid crystal polyester resin of this embodiment contains LCPA and LCPB, the mass ratio of the LCPA content to the LCPB content (LCPA content:LCPB content) is preferably 1:99 to 99:1, and more preferably 5:95 to 30:70.

[0058] The liquid crystal polyester resin of this embodiment is preferably produced by melt-polymerizing raw material monomers corresponding to the repeating units constituting the resin, and then solid-phase polymerizing the resulting polymer, which allows for the easy production of a high-molecular-weight liquid crystal polyester resin having high heat resistance, strength, and rigidity. The melt polymerization may be carried out in the presence of a catalyst, such as a metal compound, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, or antimony trioxide, or a nitrogen-containing heterocyclic compound, such as 4-(dimethylamino)pyridine or 1-methylimidazole, with the nitrogen-containing heterocyclic compound being preferred.

[0059] The content of the liquid crystal polyester resin in the resin composition of this embodiment is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, based on the total amount of the resin composition. On the other hand, the content of the liquid crystal polyester resin is preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less, based on the total amount of the resin composition. For example, the content of the liquid crystal polyester resin is preferably 30% by mass or more and 95% by mass or less, more preferably 40% by mass or more and 90% by mass or less, and even more preferably 50% by mass or more and 85% by mass or less, based on the total amount of the resin composition.

[0060] <Fluoropolymer> Specific examples of the fluororesin of the resin composition of this embodiment include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, polyvinylidene fluoride (PVDF), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (perfluoroalkoxyalkane, PFA).

[0061] Of the above, PTFE is preferred as the fluororesin for the resin composition of this embodiment, from the viewpoint of further improving the sliding properties of a molded article produced using the resin composition.

[0062] As described above, the fluororesin of the resin composition of the present embodiment contains a first fluororesin exhibiting a first endothermic peak temperature and a second fluororesin exhibiting a second endothermic peak temperature, and typically contains a first fluororesin exhibiting the first endothermic peak temperature and a second fluororesin exhibiting the second endothermic peak temperature that have different molecular weights.

[0063] More specifically, the resin composition of this embodiment preferably contains a first fluororesin having a number average molecular weight (Mn) of 30,000 to 50,000 and a second fluororesin having a number average molecular weight (Mn) of 10,000 to 25,000.

[0064] ·Method for measuring number average molecular weight In this specification, the number average molecular weight (Mn) is the number average molecular weight (Mn) determined by the method described in J. Appl. Polym. Sci. 1973, 17, 3253. Specifically, it refers to the value calculated from the heat of crystallization (ΔHc: cal / g) determined using a differential scanning calorimeter (product name: DSC-60 Plus, manufactured by Shimadzu Corporation) using the following formula (m-1). Here, the heat of crystallization (ΔHc) is the heat determined from the area of ​​the crystallization peak in the DSC curve. Number average molecular weight (Mn)=2.1×10 10 ΔHc -5.16 (m-1)

[0065] The first fluororesin and the second fluororesin contained in the resin composition of this embodiment are both preferably PTFE.

[0066] The content of the fluororesin in the resin composition of this embodiment is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the total amount of the resin composition. On the other hand, the content of the fluororesin is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, based on the total amount of the resin composition. For example, the content of the fluororesin is preferably 1% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 35% by mass or less, and even more preferably 15% by mass or more and 30% by mass or less, relative to the total amount of the resin composition.

[0067] When the content of the fluororesin in the resin composition of the present embodiment relative to the total amount of the resin composition is within the above-mentioned preferred range, the sliding properties of a molded article produced using the resin composition are further improved.

[0068] The content of the fluororesin in the resin composition of this embodiment is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more, per 100 parts by mass of the liquid crystal polyester resin. On the other hand, the content of the fluororesin is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, relative to 100 parts by mass of the liquid crystal polyester resin. For example, the content of the fluororesin is preferably 10 parts by mass or more and 50 parts by mass or less, more preferably 15 parts by mass or more and 45 parts by mass or less, and even more preferably 20 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the liquid crystal polyester resin.

[0069] When the content of the fluororesin in the resin composition of the present embodiment relative to 100 parts by mass of the liquid crystal polyester resin is within the above-mentioned preferred range, the sliding properties of a molded article produced using the resin composition are further improved.

[0070] <Optional ingredients> The resin composition of this embodiment may contain optional components other than the liquid crystal polyester resin and fluororesin described above, such as fillers, resins other than the liquid crystal polyester resin and fluororesin described above, flame retardants, conductivity imparting agents, crystal nucleating agents, ultraviolet absorbers, antioxidants, vibration dampers, antibacterial agents, insect repellents, deodorizing agents, color inhibitors, heat stabilizers, release agents, antistatic agents, plasticizers, lubricants, dyes, foaming agents, foam control agents, viscosity modifiers, surfactants, etc.

[0071] <Filler> Examples of the filler include fibrous fillers, plate-like fillers, spherical fillers, powdery fillers, irregularly shaped fillers, and the like.

[0072] Examples of fibrous fillers include glass fiber, PAN-based carbon fiber, pitch-based carbon fiber, silica-alumina fiber, silica fiber, alumina fiber, other ceramic fibers, liquid crystal polymer (LCP) fiber, aramid fiber, polyethylene fiber, etc. Also included are whiskers such as wollastonite and potassium titanate fiber.

[0073] Examples of the plate-like filler include talc, mica, graphite, and wollastonite. The flake-like filler may be surface-treated or untreated. Examples of mica include natural micas such as muscovite, phlogopite, fluorphlogopite, and tetrasilicic mica, and artificially produced synthetic micas.

[0074] Examples of spherical fillers include glass beads and glass balloons.

[0075] Examples of powder fillers include calcium carbonate, dolomite, clay barium sulfate, titanium oxide, carbon black, conductive carbon, and fine silica.

[0076] Examples of irregularly shaped fillers include glass flakes and irregular cross-section glass fibers.

[0077] Of the above, the filler for the resin composition of this embodiment is preferably a plate-like filler or a powdery filler, more preferably a plate-like filler or titanium oxide, and even more preferably mica or titanium oxide.

[0078] The filler content of the resin composition of this embodiment is preferably 1% by mass or more and 40% by mass or less, more preferably 10% by mass or more and 35% by mass or less, and even more preferably 15% by mass or more and 30% by mass or less, relative to the total amount of the resin composition.

[0079] When the content of the filler in the resin composition of the present embodiment relative to the total amount of the resin composition is within the above-mentioned preferred range, the sliding properties of a molded article produced using the resin composition are further improved.

[0080] The content of the filler in the resin composition of this embodiment is preferably 10 parts by mass or more and 50 parts by mass or less, more preferably 20 parts by mass or more and 45 parts by mass or less, and even more preferably 30 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the liquid crystal polyester resin.

[0081] When the content of the filler in the resin composition of the present embodiment relative to 100 parts by mass of the liquid crystal polyester resin is within the above-mentioned preferred range, the sliding properties of a molded article produced using the resin composition are further improved.

[0082] <Resins other than liquid crystal polyester resin and fluororesin> Resins other than liquid crystal polyester resins and fluororesins include polyolefin resins such as polyethylene, polypropylene, polybutadiene, and polymethylpentene; vinyl resins such as vinyl chloride, vinylidene chloride vinyl acetate, and polyvinyl alcohol; polystyrene, acrylonitrile-styrene resin (AS resin), and acrylonitrile-butadiene-styrene resin (ABS resin); polyamide 6 (nylon 6), polyamide 66 (nylon 66), polyamide 11 (nylon 11), polyamide 12 (nylon 12), polyamide 46 (nylon 46), polyamide 610 (nylon 610), polytetramethylene terephthalamide (nylon 4T), polyhexamethylene terephthalamide (nylon 6T), polymetaxylylene adipamide (nylon MXD ...11 (nylon 11), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 (nylon 12), polyamide 12 ( Examples of suitable resins include polyamide resins such as poly(amethylene terephthalamide) (nylon 9T) and poly(decamethylene terephthalamide) (nylon 10T); polyester resins such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polytrimethylene terephthalate; polysulfone resins such as modified polysulfone, polyethersulfone, polysulfone, and polyphenylsulfone; polyphenylene sulfides such as linear polyphenylene sulfide, crosslinked polyphenylene sulfide, and semi-crosslinked polyphenylene sulfide; polyether ketones such as polyether ketone, polyether ether ketone, and polyether ketone ketone; polycarbonate; polyphenylene ether; and polyimide resins such as thermoplastic polyimide, polyamide imide, and polyether imide.

[0083] The resin composition of the present embodiment may contain a resin other than the liquid crystal polyester resin and the fluororesin, as long as the effects of the present invention are not impaired. The content of resins other than the liquid crystal polyester resin and the fluororesin is preferably 10 mass% or less, more preferably 5 mass% or less, and even more preferably 1 mass% or less, relative to the total amount of the resin composition. It is particularly preferable that the resin composition of this embodiment does not contain any resins other than the liquid crystal polyester resin and the fluororesin.

[0084] The resin composition of the present embodiment described above contains a liquid crystal polyester resin and a fluororesin having an average particle size of 20 μm or less, a first endothermic peak temperature of 328°C or more, and a second endothermic peak temperature of 325°C or less. Conventional resin compositions containing low-molecular-weight fluororesins generally have the problem that the low-molecular-weight fluororesins have lower durability than high-molecular-weight fluororesins, and when a molded article is produced from a resin composition containing a low-molecular-weight fluororesin, the fluororesin tends to fall off from the molded article. Furthermore, although high-molecular-weight fluororesin has high durability, when a molded article is produced from a resin composition containing a high-molecular-weight fluororesin, it is difficult to improve the dispersibility of the fluororesin in the molded article, and therefore fracture progresses from the interface between the fluororesin and the resin other than the fluororesin contained in the resin composition, making it difficult to improve the durability of the molded article. On the other hand, the fluororesin of the resin composition of this embodiment contains a plurality of fluororesins having different specific endothermic peak temperatures, typically different specific molecular weights, and the average particle size of the fluororesins is controlled to be 20 μm or less, thereby improving durability and dispersibility. In addition, the resin composition of the present embodiment contains a liquid crystal polyester resin that has high heat resistance and mechanical strength. Therefore, according to the resin composition of this embodiment, a molded article having good sliding properties can be produced.

[0085] The resin composition of the present embodiment has the following aspects. "1" A resin composition comprising a liquid crystal polyester resin and a fluororesin, wherein the fluororesin has an average particle size of 20 μm or less as determined by image analysis of an SEM image of the fluororesin, and the fluororesin includes a first fluororesin having an endothermic peak temperature of 328°C or more and a second fluororesin having an endothermic peak temperature of 325°C or less when measuring the endothermic peaks at a temperature increase rate of 1°C / min using a differential scanning calorimeter.

[0086] "2" The endothermic peak temperature of the first fluororesin is preferably 328°C or higher and 350°C or lower, more preferably 328°C or higher and 340°C or lower, and even more preferably 328°C or higher and 333°C or lower, The resin composition according to "1", wherein the endothermic peak temperature of the second fluororesin is preferably 300°C or higher and 325°C or lower, more preferably 310°C or higher and 325°C or lower, and even more preferably 320°C or higher and 325°C or lower.

[0087] [3] The resin composition according to [1] or [2], wherein the first fluororesin and the second fluororesin are both PTFE.

[0088] "4" The resin composition according to any one of "1" to "3", wherein the liquid crystal polyester resin contains a liquid crystal polyester resin containing a repeating unit having a 2,6-naphthylene group and a liquid crystal polyester resin not containing a repeating unit having a 2,6-naphthylene group.

[0089] "5" The liquid crystal polyester resin has the repeating unit (1), the repeating unit (2), and the repeating unit (3) described above, and any one of the repeating units (1) to (3) has a 2,6-naphthylene group; The resin composition according to any one of "1" to "4", which contains a liquid crystal polyester resin having the repeating unit (1), the repeating unit (2), and the repeating unit (3), wherein none of the repeating units (1) to (3) has a 2,6-naphthylene group.

[0090] [6] The resin composition according to any one of [1] to [5], further containing a filler.

[0091] A resin composition having the property that, when a molded article is produced under the following conditions using the resin composition according to any one of "7", "1" to "6", and the limiting PV value of the molded article is determined using a Suzuki friction and wear tester, the limiting PV value is preferably 85 MPa m / min or more, more preferably 90 MPa m / min or more, and even more preferably 150 MPa m / min or more. [Production conditions for molded products] The mixture is placed in an injection molding machine UH1000 (manufactured by Nissei Plastic Industrial Co., Ltd.) with a cylinder temperature of 340°C, and injected into a mold with a mold temperature of 120°C at an injection speed of 20 mm / s, a screw rotation speed of 100 rpm, a holding pressure of 50 MPa, and a back pressure of 3 MPa to produce a molded body measuring 64 mm x 64 mm x 3 mm. [Method for measuring limit PV value] A metal ring coated with silicone oil having a kinematic viscosity of 450 to 600 Pa s at 25°C is placed on the molded body, and a load is applied while the metal ring is rotated. A load (stress) of -20 N is determined below the load at which scraping occurs on the surface of the molded body, and the limiting PV value (MPa m / min) is calculated using the following formula. Limit PV value (MPa·m / min) = stress·test speed (40m / min) <Measurement conditions> Mating material: SUS304 (Ra: 0.02mm or less). Measurement temperature: 25℃. Test speed: 40m / min. Load profile: 50N for 5 minutes, 100N for 3 minutes, and for loads above 100N, the load was increased by 20N increments, with each load increasing for 1 minute. Contact area between ring and molded body: 2.0 cm 2

[0092] (Method of producing resin composition) One aspect of the method for producing the resin composition of this embodiment includes the steps of preparing raw material powder containing a first liquid crystal polyester having a flow initiation temperature of 320 to 340°C, a second liquid crystal polyester having a flow initiation temperature of 310 to 330°C, which is lower than the flow initiation temperature of the first liquid crystal polyester, a first fluororesin having a number average molecular weight (Mn) of 30,000 to 50,000, and a second fluororesin having a number average molecular weight (Mn) of 10,000 to 25,000, and melt-kneading the raw material powder to obtain a resin composition (molten material).

[0093] <First liquid crystal polyester> The first liquid crystal polyester preferably has a flow starting temperature of 280°C or higher, more preferably 280°C or higher and 400°C or lower, and even more preferably 320°C or higher and 340°C or lower. A specific example of the first liquid crystal polyester is LCPA.

[0094] <Second liquid crystal polyester> The second liquid crystal polyester is a liquid crystal polyester having a flow initiation temperature lower than that of the first liquid crystal polyester. The second liquid crystal polyester preferably has a flow initiation temperature of 280°C or higher, more preferably 280°C or higher and 400°C or lower, and even more preferably 310°C or higher and 330°C or lower. A specific example of the second liquid crystal polyester is LCPB.

[0095] The first and second fluororesins are the same as the first and second fluororesins described above.

[0096] The step of melt-kneading the raw material powder can be carried out using, for example, an extruder. Examples of the extruder include a single-screw extruder and a twin-screw extruder.

[0097] When the resin composition of this embodiment is in the form of pellets, the resulting melt is extruded in the form of strands through a circular nozzle (discharge port), and then cut with a strand cutter to obtain a pellet-shaped resin composition.

[0098] (Molded body) The molded article of this embodiment is a molded article produced using the above-described resin composition. The molded article of this embodiment can be obtained by a known molding method using the resin composition. As a molding method for the resin composition of this embodiment, a melt molding method is preferred, and examples thereof include injection molding, extrusion molding such as a T-die method or an inflation method, compression molding, blow molding, vacuum molding, and press molding. Among these, injection molding is preferred.

[0099] For example, when the above-mentioned resin composition is used as a molding material and molded by injection molding, the resin composition is melted using a known injection molding machine, and the molten resin composition is injected into a mold to mold it. Here, when the resin composition is fed into the injection molding machine, each component may be fed separately into the injection molding machine, or some or all of the components may be mixed in advance and the mixture may be fed into the injection molding machine, or the resin composition may be molded into pellets and then fed into the injection molding machine. Examples of known injection molding machines include the TR450EH3 manufactured by Sodick Co., Ltd. and the PS40E5ASE hydraulic horizontal molding machine manufactured by Nissei Plastic Industrial Co., Ltd.

[0100] The temperature conditions for injection molding are determined appropriately depending on the type of resin composition, and it is preferable to set the cylinder temperature of the injection molding machine to a temperature 10 to 80° C. higher than the flow initiation temperature of the resin composition used.

[0101] The temperature of the mold is preferably set in the range of room temperature (25°C) to 180°C in terms of the cooling rate of the resin composition and productivity. Other injection conditions such as the screw rotation speed, back pressure, injection speed, pressure holding, and pressure holding time may be adjusted as appropriate.

[0102] The molded article of this embodiment can be generally used in any application to which a resin composition can be applied. The molded article of this embodiment can be used for, for example, electrical and electronic components such as connectors, sockets, relay parts, coil bobbins, optical pickups, oscillators, printed wiring boards, circuit boards, semiconductor packages, and computer-related parts; semiconductor manufacturing process-related parts such as IC trays and wafer carriers; household electrical appliance parts such as VTRs, televisions, irons, air conditioners, stereos, vacuum cleaners, refrigerators, rice cookers, and lighting fixtures; lighting fixture parts such as lamp reflectors and lamp holders; audio product parts such as compact discs, laser discs (registered trademark), and speakers; communication equipment parts such as ferrules for optical cables, telephone parts, facsimile parts, and modems; separation claws, heater holders, copier and printer related parts; mechanical parts such as impellers, fan gears, gears, bearings, motor parts and cases; automotive parts such as automotive mechanism parts, engine parts, engine room parts, electrical parts, and interior parts; cooking utensils such as microwave cooking pots and heat-resistant tableware; heat insulation and soundproofing materials such as flooring and wall materials, support materials such as beams and pillars, building materials such as roofing materials, or civil engineering and construction materials; aircraft, spacecraft, and space equipment parts; radiation facility components such as nuclear reactors, marine facility components, cleaning jigs, optical equipment parts, valves, pipes, nozzles, filters, membranes, medical equipment parts and medical materials, sensor parts, sanitary fixtures, sporting goods, and leisure goods.

[0103] The molded article of the present embodiment described above has good sliding properties because the above-mentioned resin composition is used. The molded article of this embodiment is particularly useful as an automobile part due to its high mechanical strength, heat resistance, and sliding properties. Among automobile parts, it is particularly useful as a damper ring. [Example]

[0104] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0105] [Flow temperature of liquid crystal polyester resin] First, using a flow tester (Shimadzu Corporation, CFT-500 type), about 2 g of liquid crystal polyester resin was filled into a cylinder equipped with a die having a nozzle with an inner diameter of 1 mm and a length of 10 mm. Next, 9.8 MPa (100 kg / cm 2 The liquid crystalline polyester resin was melted and extruded from the nozzle while being heated at a rate of 4°C / min under a load of 1000 kJ / s (1000 kcal / min), and the temperature at which the resin showed a viscosity of 4800 Pa·s (48,000 poise) (flow initiation temperature) was measured and used as the flow initiation temperature of the liquid crystalline polyester resin.

[0106] [Production Example 1: Production of Liquid Crystal Polyester Resin (LCP1)] A reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer, and a reflux condenser was charged with 994.5 g (7.2 mol) of p-hydroxybenzoic acid, 299.0 g (1.8 mol) of terephthalic acid, 99.7 g (0.6 mol) of isophthalic acid, 446.9 g (2.4 mol) of 4,4'-dihydroxybiphenyl, and 1347.6 g (13.2 mol) of acetic anhydride. The gas in the reactor was replaced with nitrogen gas, and then 0.18 g of 1-methylimidazole was added. The mixture was heated from room temperature to 150°C over 30 minutes while stirring under a nitrogen gas stream, 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 over 2 hours and 50 minutes while distilling off the by-produced acetic acid and unreacted acetic anhydride. When an increase in torque was observed, the contents were removed from the reactor and cooled to room temperature, yielding a solid prepolymer. Next, this prepolymer was pulverized using a pulverizer, and the resulting pulverized material was heated in a nitrogen atmosphere from room temperature to 250°C over 1 hour, then from 250°C to 295°C over 5 hours, and held at 295°C for 3 hours, thereby carrying out solid-state polymerization. The obtained solid-phase polymer was cooled to room temperature to obtain a powdered liquid crystal polyester resin (LCP1), which had a flow-initiation temperature of 327°C.

[0107] The liquid crystal polyester resin (LCP1) has the following ratio of Ar to the total amount of all repeating units.1 60 mol % of repeating units (1) in which R is a 1,4-phenylene group, Ar 2 15 mol % of repeating units (2) in which R is a 1,4-phenylene group, Ar 2 5 mol % of repeating units (2) in which is a 1,3-phenylene group, and Ar 3 is a 4,4'-biphenylylene group, and has 20 mol % of repeating units (3) in which X and Y are oxygen atoms.

[0108] [Production Example 2: Production of Liquid Crystal Polyester Resin (LCP2)] A reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer, and a reflux condenser was charged with 1,034.99 g (5.5 mol) of 6-hydroxy-2-naphthoic acid, 378.33 g (1.75 mol) of 2,6-naphthalenedicarboxylic acid, 83.07 g (0.5 mol) of terephthalic acid, 272.52 g of hydroquinone (2.475 mol: a 0.225 molar excess relative to the total amount of 2,6-naphthalenedicarboxylic acid and terephthalic acid), 1,226.87 g (12 mol) of acetic anhydride, and 0.17 g of 1-methylimidazole as a catalyst. The gas in the reactor was then replaced with nitrogen gas, and the mixture was heated from room temperature to 145°C over 15 minutes with stirring under a nitrogen gas stream, and refluxed at 145°C for 1 hour. Next, while distilling off by-product acetic acid and unreacted acetic anhydride, the temperature was increased from 145°C to 310°C over 3 hours and 30 minutes. After holding at 310°C for 3 hours, the contents were removed and cooled to room temperature. The resulting solid was crushed to a particle size of approximately 0.1-1 mm using a crusher. Then, in a nitrogen atmosphere, the temperature was increased from room temperature to 250°C over 1 hour, then from 250°C to 310°C over 10 hours, and held at 310°C for 5 hours, thereby carrying out solid-state polymerization. After solid-state polymerization, the contents were cooled to obtain a powdered liquid crystal polyester resin (LCP2). The flow initiation temperature of the resulting liquid crystal polyester resin (LCP2) was 324°C.

[0109] Liquid crystal polyester resin (LCP2) has Ar 1 55 mol % of repeating units (1) in which Ar is a 2,6-naphthylene group, 2 17.5 mol % of repeating unit (2) in which is a 2,6-naphthylene group, Ar2 5 mol % of repeating units (2) in which is a 1,4-phenylene group, and Ar 3 is a 1,4-phenylene group, and X and Y are oxygen atoms, and the repeating unit (3) is present in 22.5 mol %.

[0110] [Production Example 3: Production of Liquid Crystal Polyester (LCP3)] A reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer, and a reflux condenser was charged with 994.5 g (7.2 mol) of p-hydroxybenzoic acid, 239.2 g (1.44 mol) of terephthalic acid, 159.5 g (0.96 mol) of isophthalic acid, 446.9 g (2.4 mol) of 4,4'-dihydroxybiphenyl, and 1347.6 g (13.2 mol) of acetic anhydride. The gas in the reactor was replaced with nitrogen gas, and then 0.18 g of 1-methylimidazole was added. The mixture was heated from room temperature to 150°C over 30 minutes while stirring under a nitrogen gas stream, 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 over 2 hours and 50 minutes while distilling off by-product acetic acid and unreacted acetic anhydride. When an increase in torque was observed, the contents were removed from the reactor and cooled to room temperature. The resulting solid was pulverized in a grinder and, under a nitrogen atmosphere, the temperature was raised from room temperature to 220°C over 1 hour, then from 220°C to 240°C over 30 minutes, and held at 240°C for 10 hours to undergo solid-state polymerization. The resulting liquid crystal polyester resin (LCP3) was then cooled to obtain a powdered liquid crystal polyester resin (LCP3). The flow initiation temperature of the resulting liquid crystal polyester resin (LCP3) was 286°C.

[0111] Liquid crystal polyester resin (LCP3) has Ar 1 60 mol % of repeating units (1) in which R is a 1,4-phenylene group, Ar 2 12 mol % of repeating units (2) in which R is a 1,4-phenylene group, Ar 2 8 mol % of repeating units (2) in which is a 1,3-phenylene group, and Ar 3 is a 4,4'-biphenylylene group, and has 20 mol % of repeating units (3) in which X and Y are oxygen atoms.

[0112] [Production Example 4: Production of Liquid Crystal Polyester (LCP4)] A reactor equipped with a stirrer, torque meter, nitrogen gas inlet tube, thermometer, and reflux condenser was charged with 994.5 g (7.2 mol) of p-hydroxybenzoic acid, 365.4 g (2.2 mol) of terephthalic acid, 33.2 g (0.2 mol) of isophthalic acid, 446.9 g (2.4 mol) of 4,4'-dihydroxybiphenyl, 1347.6 g (13.2 mol) of acetic anhydride, and 0.194 g of 1-methylimidazole as a catalyst. The mixture was stirred at room temperature for 15 minutes to thoroughly flush the reactor with nitrogen gas, and then heated with stirring. When the internal temperature reached 145°C, the mixture was stirred for 1 hour while maintaining the same temperature. The resulting prepolymer was then cooled to room temperature while distilling off the by-product acetic acid and unreacted acetic anhydride. The resulting prepolymer was then pulverized in a mill to obtain a liquid crystalline polyester powder (particle size: approximately 0.1 mm to approximately 1 mm). The liquid crystal polyester powder was then heated from room temperature to 300°C over 5 hours in a nitrogen atmosphere to allow the solid-state polymerization reaction to proceed, and then cooled to obtain a powdered liquid crystal polyester resin (LCP4). The flow initiation temperature of the liquid crystal polyester resin (LCP4) was 361°C.

[0113] Liquid crystal polyester resin (LCP4) has the following characteristics: Ar 1 60 mol % of repeating units (1) in which R is a 1,4-phenylene group, Ar 2 18 mol % of repeating units (2) in which R is a 1,4-phenylene group, Ar 2 2 mol % of repeating units (2) in which is a 1,3-phenylene group, and Ar 3 is a 4,4'-biphenylylene group, and has 20 mol % of repeating units (3) in which X and Y are oxygen atoms.

[0114] [Preparation of fluororesin] As the first fluororesin, high molecular weight PTFE (product name "Fluon (registered trademark) L169J", manufactured by AGC) was prepared. Furthermore, a low molecular weight PTFE (product name "Dyneon TF9205", manufactured by 3M) was prepared as the second fluororesin.

[0115] [Measurement of endothermic peaks of fluororesin 1] The first and second fluororesins were measured for their endothermic peaks when heated at a rate of 1° C. / min using a differential scanning calorimeter (manufactured by Shimadzu Corporation, trade name "DSC-50"). As a result, the endothermic peak of the first fluororesin was 330°C, and the endothermic peak of the second fluororesin was 324°C.

[0116] <Production of Molded Product> Example 1 The pelletized resin composition was placed in an injection molding machine UH1000 (manufactured by Nissei Plastic Industrial Co., Ltd.) with a cylinder temperature of 340°C, and injected into a mold with a mold temperature of 120°C at an injection speed of 20 mm / s, a screw rotation speed of 100 rpm, a holding pressure of 50 MPa, and a back pressure of 3 MPa to produce an injection-molded test piece (surface roughness Ra = 3 μm) measuring 64 mm × 64 mm × 3 mm.

[0117] [Measurement of endothermic peaks of fluororesin 2] The pellet-shaped resin composition of Example 1 was subjected to aminolysis to extract only the fluororesin, and the endothermic peak of the fluororesin in the pellet-shaped resin composition of Example 1 was measured in the same manner as in [Measurement of the endothermic peak of the fluororesin 1] above. The results are shown in Figure 1. As shown in FIG. 1, an endothermic peak at 330°C attributed to the first fluororesin and an endothermic peak at 324°C attributed to the second fluororesin were confirmed. From this, it is presumed that the fluororesins in the pellet-shaped resin compositions of Examples 2 to 6 also show an endothermic peak at 330°C derived from the first fluororesin and an endothermic peak at 324°C derived from the second fluororesin.

[0118] [Evaluation of average particle size of fluororesin] The average particle size of the fluororesin in the resin composition of each example was determined by image analysis of the SEM image. Specifically, for each example of the resin composition in pellet form, a cross-section processing was performed using a cross-section specimen preparation device (manufactured by JEOL Ltd., "Cross Section Polisher SM-09010") at an acceleration voltage of 4.5 kV for 20 hours. Next, a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, "S-4800") was used to capture a cross-sectional image of each example of the resin composition in pellet form at an acceleration voltage of 10 kV. The cross-sectional images were captured using an attached YAG backscattered electron detector at an observation magnification of 500x. Next, the average particle size of the fluororesin in the resin composition was determined using image analysis software (manufactured by Mitani Shoji Co., Ltd., "WinROOF" Ver. 3.54) by the following analysis method.

[0119] ≪Analysis method≫ The obtained cross-sectional image was subjected to median processing with a filter size of 5 × 5, and then the region containing the liquid crystal polyester resin and the region containing the fluororesin were binarized (the threshold value during binarization was set to 100). After using the processed image, noise and regions cut off in the middle of the image edge were removed, and the circle-equivalent diameters of 150 fluororesin regions were measured. The average of the obtained measurements was calculated and used as the average particle diameter of the fluororesin in the resin composition. The results are shown in Tables 1 and 2 as "average particle size (μm) of fluororesin."

[0120] [Evaluation of limit PV value] The limiting PV value of each molded body was determined using a Suzuki-type friction and wear tester (ring-on-disc). Specifically, a metal ring coated with silicone oil having a kinematic viscosity of 450 to 600 Pa·s at 25°C was placed on the molded body of each example, and a load was applied while the metal ring was rotated. The load (stress) of -20 N below the load at which scraping occurred on the surface of each molded body was determined, and the limiting PV value (MPa·m / min) was calculated using the following formula. Limit PV value (MPa·m / min) = stress·test speed (40m / min)

[0121] The specific measurement conditions are as follows: Mating material: SUS304 (Ra: 0.02mm or less). Measurement temperature: 25℃. Test speed: 40m / min. Load profile: 50N for 5 minutes, 100N for 3 minutes, and for loads above 100N, the load was increased by 20N increments, with each load increasing for 1 minute. Contact area between ring and molded body: 2.0 cm 2 The results are shown in Tables 1 and 2 as "limiting PV value (MPa m / min)." The "limiting PV value (MPa m / min)" indicates the limit at which the sliding surface of the material deforms or melts due to frictional heat, and is a value that serves as an index of sliding properties. The higher the value, the better the sliding properties.

[0122] [Table 1]

[0123] [Table 2]

[0124] In Tables 1 and 2, the abbreviations have the following meanings: The numerical values ​​in the tables are the contents (% by mass) when the resin composition is taken as 100% by mass. LCP1 to LCP4: The above-mentioned liquid crystal polyester resins LCP1 to LCP4 PTFE1: Low molecular weight PTFE (trade name "Dyneon (registered trademark) TF9205", manufactured by 3M) PTFE2: High molecular weight PTFE (product name "Fluon (registered trademark) L169J", manufactured by AGC) PES1: Polyethersulfone (product name "Sumikaexcel (registered trademark) PES 5003P", manufactured by Sumitomo Chemical Co., Ltd.) M1: Mica (product name "YM-25S", manufactured by Yamaguchi Mica Co., Ltd.) M2: Titanium oxide (product name "CR60", manufactured by Ishihara Sangyo Kaisha)

[0125] As shown in Tables 1 and 2, it was confirmed that the molded bodies produced using the resin compositions of the Examples had higher limiting PV values ​​and higher sliding properties than the molded bodies produced using the resin compositions of the Comparative Examples.

[0126] 2 to 6 are SEM images of the cross section of each example of the resin composition in the form of pellets, in which the continuous phase is the liquid crystal polyester resin and the dispersed phase is the fluororesin. Fig. 2 is an SEM image of the resin composition of Example 1. It can be seen that the fluororesin is uniformly dispersed in the resin composition of Example 1. From this, it is presumed that the molded article produced using the resin composition of Example 1 had a high limit PV value. 3 and 4 are SEM images of the resin compositions of Comparative Examples 1 and 2, respectively. It can be seen that the fluororesin aggregates in the resin compositions of Comparative Examples 1 and 2. From this, it is presumed that the molded articles produced using the resin compositions of Comparative Examples 1 and 2 had low limiting PV values. 5 is an SEM image of the resin composition of Comparative Example 5. Since the resin composition of Comparative Example 5 contains only a low-molecular-weight fluororesin, the fluororesin was uniformly dispersed. However, low-molecular-weight fluororesin itself does not have high durability and tends to fall off from the molded article, so it is presumed that the molded article produced using the resin composition of Comparative Example 5 had a low limiting PV value. Fig. 6 is an SEM image of the resin composition of Comparative Example 6. Since the resin composition of Comparative Example 6 contains only a high molecular weight fluororesin, it can be seen that the fluororesin aggregates. From this, it is presumed that the molded article produced using the resin composition of Comparative Example 6 had a low limiting PV value.

Claims

1. Contains a liquid crystal polyester resin and a fluororesin, The liquid crystal polyester resin includes a first liquid crystal polyester having a flow initiation temperature of 320 to 340°C and a second liquid crystal polyester having a flow initiation temperature of 310 to 330°C and a lower flow initiation temperature than the first liquid crystal polyester, the fluororesin includes a first fluororesin having a number average molecular weight (Mn) of 30,000 to 50,000 and a second fluororesin having a number average molecular weight (Mn) of 10,000 to 25,000; the fluororesin has an average particle size of 20 μm or less, as determined by image analysis of an SEM image of the fluororesin; The fluororesin is a resin composition that, when the endothermic peaks are measured using a differential scanning calorimeter while heating at a rate of 1°C / min, exhibits a first endothermic peak temperature of 328°C or higher and a second endothermic peak temperature of 325°C or lower.

2. The resin composition according to claim 1, wherein the first endothermic peak temperature is 328°C or higher and 333°C or lower, and the second endothermic peak temperature is 320°C or higher and 325°C or lower.

3. 3. The resin composition according to claim 1, wherein the liquid crystal polyester resin contains a repeating unit having a 2,6-naphthylene group.

4. The resin composition according to any one of claims 1 to 3, further comprising a filler.

5. The resin composition according to any one of claims 1 to 4, wherein the content of the fluororesin is 20 to 40 parts by mass with respect to 100 parts by mass of the liquid crystal polyester resin.

6. A molded article produced using the resin composition according to any one of claims 1 to 5.

Images