Thermoplastic polyester resin composition and molded article using the same

Abstract

To provide a thermoplastic polyester resin composition that has excellent mechanical strength, toughness and low wear resistance, whose pellets can be reliably supplied to a molding machine during injection molding, and a molding including the same.SOLUTION: A resin composition comprises, relative to (A) thermoplastic polyester resin (A component) 100 pts.wt., (B) modified polyethylene resin (B component) 4-25 pts.wt., (C) wholly aromatic polyamide fiber (C component) 10-35 pts.wt. and (D) epoxy resin represented by the general formula (1) (D component) 0.5-8 pts.wt.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermoplastic polyester resin composition having excellent mechanical strength, toughness, and low abrasion properties, and also having excellent feedability into a molding machine during injection molding of pellets of the resin composition, and to a molded article using the same. [Background technology]

[0002] Thermoplastic polyester resins and polyarylene sulfide resins have traditionally been widely used in electrical and electronic components, home appliances, and automotive parts because their excellent low water absorption means minimal mechanical properties and dimensional change due to environmental changes, allowing them to exhibit stable performance. Among these, sliding component applications such as various gears and bearings require not only the above-mentioned dimensional stability but also excellent mechanical strength and toughness as components, as well as low wear when sliding against mating materials, because they are exposed to continuous or intermittent frictional forces. In recent years, there has been a demand for components that can achieve long life even under harsh environments such as high temperatures and high loads, and this has led to a need for higher levels of low wear than before.

[0003] Patent Document 1 proposes a sliding component for conveyor chains molded from a resin composition comprising a thermoplastic resin, a fibrous filler, and a solid lubricant. However, the low wear properties are insufficient even under low loads, and further improvement is needed. Patent Document 2 proposes a resin composition comprising an aromatic polyester resin, a polyolefin polymer, and a fibrous reinforcing material as a resin composition with excellent low wear and impact resistance. However, the toughness and low wear properties are insufficient for use in current sliding component applications. Patent Document 3 proposes a resin composition comprising a polyarylene sulfide resin, a wholly aromatic polyamide fiber, a fluororesin, and a specific epoxy resin as a resin composition with excellent impact strength, tensile strength at break, and tensile elongation at break. However, there is no mention of low wear properties, and the tensile strength at break is not sufficient for use as a sliding component. In addition, pellets of a resin composition containing aramid fibers may have a problem in that the aramid fibers on the surface interfere with each other, causing the pellets to accumulate in the hopper of an injection molding machine and not be fed. However, no method has been proposed to address this problem, which can be applied to systems containing a wider range of solid lubricants. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-124056 [Patent Document 2] Japanese Patent Application Publication No. 5-222278 [Patent Document 3] Japanese Patent Application Publication No. 2020-41019 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a thermoplastic polyester resin composition which has excellent mechanical strength, toughness, and low abrasion properties and is easy to feed into a molding machine during injection molding of pellets of the resin composition, and a molded article using the same. [Means for solving the problem]

[0006] As a result of extensive research into solving the above-mentioned problems, the present inventors discovered that the above-mentioned object can be achieved by blending a thermoplastic polyester resin with a modified polyethylene resin, a wholly aromatic polyamide fiber, and a specific epoxy resin in specific proportions, thereby arriving at the present invention.

[0007] That is, the above-mentioned object is achieved by a resin composition characterized by containing 100 parts by weight of (A) thermoplastic polyester resin (component A), 4 to 25 parts by weight of (B) modified polyethylene resin (component B), 10 to 35 parts by weight of (C) wholly aromatic polyamide fiber (component C), and 0.5 to 8 parts by weight of (D) epoxy resin (component D) represented by the following general formula (1):

[0008] [ka]

[0009] (In formula (1), m is an average value and is an integer of 1 or greater. R1 and R2 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a trifluoromethyl group. X each independently represents a hydrogen atom or a glycidyl group, and at least one of the multiple Xs is a glycidyl group.) [Effects of the Invention]

[0010] According to the present invention, there can be provided a thermoplastic polyester resin composition which has excellent mechanical strength, toughness, and low abrasion, and which also has excellent feedability to a molding machine during injection molding of pellets of the resin composition. Molded articles obtained from the resin composition of the present invention can be suitably used as sliding members for use in the fields of, for example, electrical and electronic equipment, semiconductors, automobiles, industrial machinery, office automation equipment, and construction. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in further detail below.

[0012] <Regarding Component A> The thermoplastic polyester resin, which is Component A of the present invention, can be produced using a dicarboxylic acid component mainly composed of a dicarboxylic acid and / or an ester-forming derivative of a dicarboxylic acid, and a glycol component mainly composed of a diol.

[0013] Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, diphenylether-4,4'-dicarboxylic acid; aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid, oxalic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, etc. One or more of these may be used, and they can be arbitrarily selected according to the purpose. When using two or more dicarboxylic acids, the usage amount of the main dicarboxylic acid is preferably 70 mol% or more, more preferably 80 mol% or more, based on the total acid component. Examples of the ester-forming derivative of the dicarboxylic acid include lower dialkyl esters of aromatic dicarboxylic acids such as 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, terephthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, diphenylether-4,4'-dicarboxylic acid; lower dialkyl esters of alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; lower dialkyl esters of aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid, oxalic acid, etc. One or more of these may be used, and they can be arbitrarily selected according to the purpose. When using two or more ester-forming derivatives of the dicarboxylic acid, the usage amount of the main ester-forming derivative of the dicarboxylic acid is preferably 70 mol% or more, more preferably 80 mol% or more, based on the total ester-forming derivative component of the dicarboxylic acid.

[0014] A small amount of a tri- or higher functional dicarboxylic acid component such as trimellitic acid, an acid anhydride such as trimellitic anhydride, or a small amount of a hydroxycarboxylic acid or an alkyl ester thereof such as lactic acid or glycolic acid may also be used, and these can be selected arbitrarily depending on the purpose.

[0015] The glycol component may be, for example, one or more alkylene glycols such as ethylene glycol, 1,4-butanediol, 1,3-propylene glycol, 1,2-propylene glycol, neopentylene glycol, hexamethylene glycol, decamethylene glycol, cyclohexanedimethanol, diethylene glycol, triethylene glycol, poly(oxy)ethylene glycol, poly(oxy)tetramethylene glycol, and poly(oxy)methylene glycol, and can be selected arbitrarily depending on the purpose. A small amount of a polyhydric alcohol component such as glycerin may also be used. The amount of the glycol component that serves as the main component is preferably 70 mol% or more, more preferably 80 mol% or more, based on the total glycol components.

[0016] The amount of the glycol component used is preferably 1.1 to 1.4 times by mole relative to the dicarboxylic acid or ester-forming derivative of the dicarboxylic acid. If the amount of the glycol component used is less than 1.1 times by mole, the esterification or transesterification reaction may not proceed sufficiently, which is not preferred. If the amount of the glycol component used is more than 1.4 times by mole, the reaction rate may slow down, although the reason is unclear, and the excess glycol component may produce a large amount of by-products such as tetrahydrofuran, which is also not preferred.

[0017] In the production of thermoplastic polyester resins, known polymerization catalysts can be used, such as titanium compounds, antimony compounds, germanium compounds, manganese compounds, and aluminum compounds, with titanium compounds being preferred. The titanium compounds used as polymerization catalysts are preferably tetraalkyl titanates, specifically tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-sec-butyl titanate, tetra-t-butyl titanate, tetra-n-hexyl titanate, tetracyclohexyl titanate, tetraphenyl titanate, and tetrabenzyl titanate, and may also be used as mixed titanates. Among these titanium compounds, tetra-n-propyl titanate, tetraisopropyl titanate, and tetra-n-butyl titanate are particularly preferred, with tetra-n-butyl titanate being most preferred. The amount of titanium compound added is preferably 10 ppm to 60 ppm, more preferably 15 ppm to 30 ppm, in terms of the titanium atom content in the resulting thermoplastic polyester resin. A titanium atom content of more than 60 ppm in the resulting thermoplastic polyester resin is undesirable because it may result in a decrease in the color tone and thermal stability of the resin composition of the present invention. On the other hand, a titanium atom content of less than 10 ppm is undesirable because it may not be possible to obtain a thermoplastic polyester resin with a sufficiently high intrinsic viscosity due to poor polymerization activity. The thermoplastic polyester resin of the present invention is preferably produced via an esterification or transesterification reaction step between a dicarboxylic acid component, primarily a dicarboxylic acid and / or its ester-forming derivative, and a glycol component in the presence of a polymerization catalyst, followed by a polycondensation reaction step. The temperature at the end of the esterification or transesterification reaction is preferably in the range of 180°C to 230°C, more preferably 180°C to 220°C. A temperature above 230°C at the end of the esterification or transesterification reaction increases the reaction rate, but may result in an increase in the production of by-products such as tetrahydrofuran, which is undesirable. If the temperature is lower than 180°C, the reaction may not proceed.The reaction product (bis glycol ether and / or its low polymer) obtained by esterification or transesterification reaction is preferably polycondensed under reduced pressure of 0.4 kPa (3 Torr) or less at a temperature not lower than the melting point of the thermoplastic polyester resin and not higher than 290 °C. When the polycondensation reaction temperature exceeds 290 °C, the reaction rate rather decreases and coloring may increase, which is not preferable.

[0018] One or more thermoplastic polyester resins may be used and can be arbitrarily selected according to the purpose. When two or more kinds are used, the supply method is not particularly limited. For example, there are a method of previously mixing pelletized or powdered thermoplastic polyester resins well with a blender and then supplying them to an extruder, and a method of supplying each alone. By using a thermoplastic polyester resin, the low wear resistance, mechanical strength, toughness of the molded body and the supply property to the molding machine during injection molding of the pellets of the resin composition can be improved. Representative thermoplastic polyester resins include, for example, polybutylene naphthalate, polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate and their copolymers. As the copolymerization component, the above-mentioned dicarboxylic acid component and glycol component can be used, but particularly polybutylene naphthalate resin, copolymer of polybutylene naphthalate resin, and a mixture of polybutylene naphthalate resin and other thermoplastic polyester resins are preferable, and polybutylene naphthalate resin is more preferable. By using these preferable thermoplastic polyester resins, the low wear resistance of the molded body may be further improved.

[0019] <Regarding Component B> The modified polyethylene resin, component B of the present invention, can be any known polyethylene resin. The use of modified polyethylene resins can improve the wear resistance and mechanical strength of molded articles. Examples of polyethylenes used as starting materials in producing modified polyethylene resins include high-density polyethylene, low-density polyethylene, and ultra-high-molecular-weight polyethylene, each with a viscosity-average molecular weight of several tens of thousands or more; polyethylene wax with a viscosity-average molecular weight of several tens of thousands or less; and mixtures of one or more of these. Various known methods can be used to modify polyethylene, including a method in which air is introduced into the polyethylene in a molten state at 140 to 180°C to introduce functional groups through an oxidation reaction; a method in which the polyethylene is suspended or dissolved in a solvent, and then a modifying monomer and a radical polymerization initiator are added and mixed at a temperature typically between 80 and 200°C to effect graft copolymerization; and a method in which the modifying monomer and a radical polymerization initiator are brought into contact with each other while melt-kneading at a temperature above the melting point, e.g., between 180 and 300°C. Examples of modifying monomers include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, and nadic acid (endo-cis-bicyclo[2.2]hept-5-ene-2,3-dicarboxylic acid). Derivatives thereof include acid halides, esters, amides, imides, and anhydrides, such as malenyl chloride, maleimide, acrylic acid amide, methacrylic acid amide, glycidyl methacrylate, maleic anhydride, citraconic acid anhydride, monomethyl maleate, dimethyl maleate, and glycidyl maleate. Among these, modified polyethylene resins modified with maleic acid, maleic anhydride, or a mixture thereof are preferred, and modified polyethylene resins modified with maleic anhydride are particularly preferred. The use of these preferred modified polyethylene resins may further improve the mechanical strength and low wear properties of molded articles.

[0020] The preferred range of the viscosity average molecular weight (Mv) of Component B is 100,000 to 1,000,000, more preferably 200,000 to 900,000, and particularly preferably 300,000 to 800,000. By using the modified polyethylene resin within this range, the mechanical strength and low wear properties of the molded body may be further improved. The viscosity average molecular weight of Component B is determined from the following formula (1) using the intrinsic viscosity [η] measured in a decalin solvent at 135°C. Mv = 5.37×10 4 [η] 1.37 ···(1)

[0021] The content of Component B is 4 to 25 parts by weight, preferably 7 to 22 parts by weight, and more preferably 10 to 20 parts by weight with respect to 100 parts by weight of Component A. When the content is less than 4 parts by weight, the wear amount during sliding increases and the mechanical strength decreases. When it exceeds 25 parts by weight, the dispersibility in the resin composition of Component B becomes insufficient and a uniform molded body cannot be obtained.

[0022] <Regarding Component C> As the wholly aromatic polyamide fiber used as Component C of the present invention, any fiber belonging to the category called wholly aromatic aramid fiber may be used. By using the wholly aromatic polyamide fiber, it is possible to achieve both ensuring the mechanical strength and toughness required for the sliding member and exhibiting excellent low wear properties. Examples of the wholly aromatic aramid fiber include meta-aramid fiber, para-aramid fiber, etc., and among them, para-aramid fiber is preferred.

[0023] The wholly aromatic polyamide constituting the fiber of the present invention is essentially obtained from one or more aromatic diamines and one or more aromatic dicarboxylic acid halides. However, a condensing agent, such as a triphenyl phosphite and pyridine system, may be added to the one or more aromatic diamines and one or more aromatic dicarboxylic acids. The wholly aromatic polyamide may be para-type or meta-type, but the para-type is more preferred. Preferred aromatic diamines include p-phenylenediamine, benzidine, 4,4"-diamino-p-terphenyl, 2,7-diaminofluorene, 3,4-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 1,4-bis-(4-aminophenoxy)benzene, 4,4'-bis-(4-aminophenoxy)biphenyl, and 9,10-bis-(4-aminophenyl)anthracene. Particularly preferred aromatic dicarboxylic acid halides are acid chlorides, such as terephthalic acid chloride, 2,6-naphthalenedicarboxylic acid chloride, and 4,4'-diphenyldicarboxylic acid chloride, as well as those containing one or more non-reactive functional groups on the aromatic ring, such as lower alkyl groups, lower alkoxy groups, halogeno groups, and nitro groups.

[0024] Furthermore, when an aromatic dicarboxylic acid is used, examples thereof include terephthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, and those containing one or more non-reactive functional groups on the aromatic ring, such as lower alkyl groups, lower alkoxy groups, halogeno groups, nitro groups, etc. Furthermore, the structure of a wholly aromatic polyamide preferred in the present invention is one whose main skeleton is represented by the following formula:

[0025] [ka]

[0026] (Here, Ar1 and Ar2 represent at least one aromatic residue selected from the group consisting of the following general formulas [I] to [IV]. Ar1 and Ar2 may be the same or different. In addition, some of the hydrogen atoms of these aromatic residues may be substituted with halogen atoms or lower alkyl groups.)

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] [ka]

[0031] In particular, when the sum of Ar1 and Ar2 is taken as 100 mol%, the sum of general formula [I] and general formula [II], the sum of general formula [I] and general formula [III], the sum of general formula [I] and general formula [IV], or general formula [I] is preferably 80 mol% or more. More preferably, the sum of general formula [I] and general formula [II], or the sum of general formula [I] and general formula [III] is 80 mol% or more. Even more preferably, the sum of general formula [I] and general formula [II], or the sum of general formula [I] and general formula [III] is 80 mol% or more, and general formula [II] or general formula [III] is 1 to 20 mol%.

[0032] The aromatic polyamide dope used as the spinning solution may be obtained by solution polymerization or by dissolving a separately obtained wholly aromatic polyamide in a solvent, but solution polymerization is preferred. A small amount of inorganic salt may be added as a solubilizer to improve solubility. Examples of such inorganic salts include lithium chloride and calcium chloride.

[0033] As the polymerization solvent or re-dissolving solvent, a generally known aprotic organic polar solvent is used, examples of which include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylpropionamide, N,N-butylamide, N,N-dimethylisobutyramide, N-methylcaprolactam, N,N-dimethylmethoxyacetamide, N-acetylpyrrolidine, N-acetylpiperidine, N-methylpiperidone-2,N,N'-dimethylethyleneurea, N,N'-dimethylpropyleneurea, N,N,N',N'-tetramethylmalonamide, N-acetylpyrrolidone, N,N,N',N'-tetramethylurea, and dimethyl sulfoxide. Further, as the re-dissolving solvent, a strong acid such as concentrated sulfuric acid or methanesulfonic acid can be used.

[0034] Although there is no particular limitation on the degree of polymerization of the wholly aromatic polyamide, a higher degree of polymerization is preferable if it dissolves in a solvent. When the wholly aromatic polyamide is solution-polymerized, the acid component and the diamine component are reacted in a substantially equimolar ratio, but either component can be used in excess to control the degree of polymerization. Furthermore, a monofunctional acid component or an amine component can be used as an end-capping agent.

[0035] When forming a wholly aromatic polyamide into a fiber, a method of wet forming a wholly aromatic polyamide dope is usually used, either by directly discharging the dope into a coagulation bath or by discharging the dope into the coagulation bath via an air gap. A poor solvent for the wholly aromatic polyamide is used in the coagulation bath, and a good solvent is usually added to adjust the coagulation rate so that the solvent of the wholly aromatic polyamide dope does not escape too quickly and cause defects in the wholly aromatic polyamide fiber. In general, it is preferable to use water as the poor solvent and the solvent of the wholly aromatic polyamide dope as the good solvent. The ratio of good solvent / poor solvent is preferably 15 / 85 to 40 / 60, depending on the solubility and coagulation properties of the wholly aromatic polyamide.

[0036] Although such wholly aromatic polyamide fibers are effective regardless of whether they are bundled or not, bundled fibers are preferred because they are easier to handle. Examples of binders for bundling include polyester resins, polyurethane resins, and polyethersulfone resins. Among these, polyester resins and polyurethane resins are preferred, and polyester resins are even more preferred. In the present invention, such wholly aromatic polyamide fibers can be used alone or as a mixture of two or more types.

[0037] Furthermore, the fiber length of such wholly aromatic polyamide fibers before being added to component A is preferably 0.5 mm to 4.0 mm, more preferably 0.8 mm to 4.0 mm, and particularly preferably 2.0 mm to 4.0 mm. If the fiber length is less than 0.5 mm, the reinforcing effect may be insufficient and the improvement in mechanical strength may be insufficient, while if it exceeds 4.0 mm, handling during production may be difficult, the fluidity of the composition may be poor, and moldability may be poor. The fiber length can be measured, for example, by taking any single fiber from a fiber bundle, measuring the fiber lengths of 50 fibers under magnification with a microscope, and taking the average of the measured fiber lengths as the fiber length.

[0038] Moreover, the form of such wholly aromatic polyamide fibers is not particularly limited, and any form can be used, but it is preferably twisted from the viewpoint of handling properties during the production of the resin composition. By using a fiber bundle with a high twist number, the supply of the wholly aromatic polyamide fibers to the extruder may be stabilized. The preferred twist number of the wholly aromatic polyamide fibers is 10 to 500 turns / m, more preferably 50 to 450 turns / m, and even more preferably 100 to 400 turns / m.

[0039] The content of the C component is 10 to 35 parts by weight, preferably 13 to 32 parts by weight, more preferably 15 to 30 parts by weight, and particularly preferably 18 to 27 parts by weight with respect to 100 parts by weight of the A component. When the content of the C component exceeds 35 parts by weight, handling during production becomes difficult, the supplyability to the molding machine during injection molding of the resin composition pellets is impaired, and continuous molding becomes difficult. On the other hand, when the content is less than 10 parts by weight, the wear amount during sliding increases and the mechanical strength also decreases.

[0040] <Regarding the D component> The resin composition of the present invention contains an epoxy resin represented by the following formula (1) as the D component.

[0041] [Chemical formula]

[0042] (In formula (1), m is an average value and is an integer of 1 or more. R1 and R2 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a trifluoromethyl group. X each independently represents a hydrogen atom or a glycidyl group, and at least one of the plurality of Xs is a glycidyl group.)

[0043] In addition, although the upper limit of m in the above formula is not particularly limited, it is preferably 300 or less, and more preferably 200 or less. When an epoxy resin other than the above epoxy resin is used, the supplyability to the molding machine during injection molding of the resin composition pellets is impaired, and the molding pressure during injection molding becomes high and molding becomes difficult.

[0044] Specific examples of the epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, and bisphenol AD ​​epoxy resin, with bisphenol A epoxy resin and bisphenol F epoxy resin being preferred. The use of these epoxy resins can efficiently improve low abrasion and mechanical strength, and may also ensure the ease of feeding pellets of the resin composition to a molding machine during injection molding. Component D can be used alone or in combination with two or more compounds. The epoxy resins are readily available, commercially available as jER1001, jER1007, jER1010, jER1256, jER4004P, and jER4010P from Mitsubishi Chemical Corporation, and as YD-011, YD-013, and YD-014 from Nippon Steel & Sumikin Chemical Co., Ltd.

[0045] The epoxy equivalent of component D is preferably 1,000 to 10,000 g / eq, more preferably 2,000 to 9,500 g / eq, and even more preferably 5,000 to 9,000 g / eq. If the epoxy equivalent is less than 1,000 g / eq, thickening during kneading and extrusion is likely to occur, increasing the molding pressure during injection molding and resulting in poor moldability. If it exceeds 10,000 g / eq, sufficient low abrasion and mechanical strength may not be achieved. The epoxy equivalent of component D is measured in accordance with JIS K 7236.

[0046] The content of component D is 0.5 to 8 parts by weight, preferably 1 to 6 parts by weight, more preferably 1 to 5 parts by weight, and particularly preferably 2 to 5 parts by weight, per 100 parts by weight of component A. If the content of component D exceeds 8 parts by weight, the molding pressure during injection molding increases, making molding difficult. On the other hand, if the content is less than 0.5 parts by weight, the amount of wear during sliding increases, and the ability to feed pellets of the resin composition into the molding machine during injection molding is impaired, making continuous molding difficult.

[0047] The resin composition of the present invention may contain other thermoplastic resins, and may contain additives such as antioxidants, impact modifiers, plasticizers, organic and inorganic fillers other than component C, flame retardants, colorants, light stabilizers, heat stabilizers, antistatic agents, antiblocking agents, lubricants other than component B, dispersants, flow modifiers, and crystal nucleating agents, as needed, within the scope of the present invention.

[0048] <Method of manufacturing resin composition> Any method can be used to produce the resin composition of the present invention. For example, the components and optionally other components can be premixed, followed by melt-kneading and pelletizing. Examples of premixing methods include a Nauta mixer, a V-blender, a Henschel mixer, a mechanochemical device, and an extrusion mixer. Premixing can also be performed using an extrusion granulator or briquetting machine. After premixing, the components are melt-kneaded in a melt mixer, typically a vented twin-screw extruder, and pelletized using a pelletizer or other device. Other examples of melt mixers include a Banbury mixer, a kneading roll, and a thermostatically stirred vessel. A vented twin-screw extruder is preferred. Alternatively, the components and optionally other components can be fed independently to a melt mixer, typically a twin-screw extruder, without premixing.

[0049] <About the molded body> Molded articles made from the resin composition of the present invention can be obtained by molding pellets produced as described above. Preferably, they are obtained by injection molding or extrusion molding. Injection molding can be performed using not only conventional molding methods but also injection compression molding, injection press molding, gas-assisted injection molding, foam molding (including methods involving the injection of supercritical fluids), insert molding, in-mold coating molding, heat-insulating mold molding, rapid heating and cooling mold molding, two-color molding, multi-color molding, sandwich molding, and ultra-high-speed injection molding. Molding can be performed using either a cold runner system or a hot runner system. In extrusion molding, molded articles can be obtained by extruding a round bar and then cutting it into a disk, or by extruding a thick sheet and then punching it into a desired shape. [Example]

[0050] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Physical properties were evaluated by the following methods. [Evaluation of Resin Composition] The specific wear rate was measured as an evaluation of low wear, the tensile strength at break as an evaluation of mechanical strength, and the tensile elongation at break as an evaluation of toughness, all by the methods described below.

[0051] (1) Specific wear rate The pellets obtained by the method described below were dried at 120°C for 7 hours and then molded in an injection molding machine (Toshiba Machine Co., Ltd., EC130SXII-4Y) at a cylinder temperature of 280°C and a mold temperature of 120°C to obtain hollow cylindrical test pieces with an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a height of 15 mm according to JIS K7218A. The test pieces were then subjected to friction and wear testing under the same conditions as a test piece made of carbon steel (S45C) using a friction and wear tester (EFM-3-G, Orientec Co., Ltd.) under a surface pressure of 0.75 MPa, a sliding speed of 500 mm / s, and a sliding distance of 3000 m. The weight loss of the test pieces after sliding was measured to the nearest 0.1 mg using an electronic balance, and the specific wear rate was calculated using the formula described in JIS K7218A. The test was performed three times, and the average value was used as the specific wear rate of the composition. The specific wear rate was 2.0 x 10 -6 mm 3 / N·m or less.

[0052] (2) Tensile breaking strength The tensile strength at break was measured using a method conforming to ISO 527. The tensile strength at break must be 85 MPa or more.

[0053] (3) Tensile elongation at break The tensile elongation at break was measured using a method in accordance with ISO 527. The tensile elongation at break must be 5% or more.

[0054] (4) Pellets supply When molding test pieces for the tensile tests described in (2) and (3) using an injection molding machine EC130SXII-4Y manufactured by Toshiba Machine Co., Ltd., the pellets in the hopper were fed into the molding machine while molding 10 test pieces continuously, and continuous molding was possible. This was marked as "○". However, when resin could not be fed into the molding machine due to interference between pellets during molding, making continuous molding difficult, this was marked as "×".

[0055] [Examples 1-12, Comparative Examples 1-10] According to the amounts shown in Table 1, components A, B, D, and other components were fed separately into a twin-screw extruder through the first feed port. Here, the first feed port refers to the feed port at the base. Component C was fed separately through the second feed port using a side feeder. For extrusion, a 30 mm diameter vented twin-screw extruder (TEX30α-31.5BW-2V, manufactured by The Japan Steel Works, Ltd.) was used. The extrusion was performed at a screw rotation speed of 200 rpm, a discharge rate of 20 kg / h, and a vent vacuum of 3 kPa to obtain pellets by melt-kneading. The extrusion temperature was 290°C.

[0056] (Component A) AI: Polybutylene naphthalate resin obtained in Production Example I <Manufacturing example I> 315.0 parts of 2,6-naphthalenedicarboxylic acid dimethyl ester, 200.0 parts of 1,4-butanediol, and 0.062 parts of tetra-n-butyl titanate were placed in an ester exchange reaction vessel, and the ester exchange reaction was carried out for 150 minutes while the temperature of the ester exchange reaction vessel was raised to 210°C. The resulting reaction product was then transferred to a polycondensation reaction vessel to initiate the polycondensation reaction. The polycondensation reaction was carried out by gradually reducing the pressure in the polycondensation reaction vessel from atmospheric pressure to 0.13 kPa (1 torr) or less over 40 minutes, while simultaneously raising the temperature to the predetermined reaction temperature of 260°C. Thereafter, the polycondensation reaction was carried out for 140 minutes while maintaining the polycondensation reaction temperature at 260°C and the pressure at 0.13 kPa (1 torr). After 140 minutes had elapsed, the polycondensation reaction was terminated, and the polybutylene naphthalate resin was extracted in the form of strands and cut into chips using a cutter while cooling with water. Next, the obtained polybutylene naphthalate resin was subjected to solid-state polymerization for 8 hours under conditions of a temperature of 213° C. and a pressure of 0.13 kPa (1 Torr) or less to obtain a polybutylene naphthalate resin.

[0057] A-II: Polyphenylene sulfide resin obtained in Production Example II <Manufacturing example II> A reactant containing 400g of para-diiodobenzene, 34g of sulfur, and 1.0g of 1,3-diiodo-4-nitrobenzene was melt-mixed at 180°C. The resulting mixture was heated from 180°C to 340°C and polymerized while reducing the pressure from ambient to 10 torr. Four hours after the start of polymerization, 0.5g of sulfur was added, and after 5 hours of polymerization, an additional 0.5g of sulfur was added and the polymerization continued for 1 hour to obtain a polymer. The polymer produced had a number-average molecular weight (Mn) of 7,630 and a polydispersity (Mw / Mn) of 4.7. The total chlorine content was below 20ppm (below the detection limit), and the total sodium content was 7ppm.

[0058] (B component) BI: Maleic anhydride modified polyethylene resin obtained in Production Example III <Production example III> A polyethylene resin blend (100 parts by weight) consisting of 15% by weight of ultra-high molecular weight polyethylene (Hi-Zex Million 630M, manufactured by Mitsui Chemicals, Inc.) with an intrinsic viscosity of 31 dL / g measured in decalic acid at 135 °C and 85% by weight of polyethylene (Hi-Zex 2200J, manufactured by Prime Polymer Co., Ltd.) with an intrinsic viscosity of 2 dL / g measured in decalic acid at 135 °C, 1 part by weight of maleic anhydride, and 0.07 parts by weight of organic peroxide (Perhexine-25B, manufactured by Nippon Oil & Fats Co., Ltd.) was mixed in a Nauta mixer. The resulting mixture was melt-kneaded in a single-screw extruder (EXT40 mm extruder, manufactured by Isuzu Chemical Engineering Co., Ltd.) set at 250 °C to obtain a BI component. The intrinsic viscosity [η] of the resulting modified polyethylene resin measured in decalic acid at 135 °C was 5.5 dL / g, and the viscosity-average molecular weight Mv was 550,000. B-II: Oxidized polyethylene wax: Hiwax 310MP (product name) (Mitsui Chemicals, Inc., viscosity average molecular weight approximately 3,000) B-III (Comparative Example): Polytetrafluoroethylene: KT-600M (product name) (manufactured by Kitamura Co., Ltd., melting point 325 to 335°C, 50% particle size 14 μm)

[0059] (C component) CI: Fully aromatic polyamide fiber: T322EH (product name) (Teijin Limited, para-aramid fiber, major diameter 12 μm, average fiber length 3 mm, polyester resin sizing agent, twist count 245 times / m) C-II: Fully aromatic polyamide fiber: T322UR (product name) (Teijin Limited, para-aramid fiber, major diameter 12 μm, average fiber length 3 mm, polyurethane resin sizing agent, twist count 60 times / m) C-III: Fully aromatic polyamide fiber: T322EH (product name) (Teijin Limited, para-aramid fiber, major diameter 12 μm, average fiber length 1 mm, polyester resin sizing agent, twist count 60 times / m) C-IV (Comparative Example): Carbon fiber: PAN-based carbon fiber HT P722 (trade name) (manufactured by Teijin Limited, fiber length 3 mm, major diameter 7 μm, polyimide-based sizing agent)

[0060] (D component) DI: Bisphenol A epoxy resin: jER1256 (product name) (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight 7,500-8,500 g / eq) D-II: Bisphenol A epoxy resin: jER1010 (product name) (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight 3,000-5,000 g / eq) D-III (Comparative Example): Trisphenolmethane type epoxy resin: EPPN-501H (product name) (manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent weight 162 to 172 g / eq)

[0061] (Other ingredients) EI: Talc: Upn HS-T0.8 (product name) (Hayashi Kasei Co., Ltd., average particle size 5 μm) E-II: Resin composition containing polycarbonate resin and carbon black in a ratio of 60% by weight to 40% by weight

[0062] [Table 1]

[0063] <Examples 1 to 12> Because the resin composition is within the scope of the present invention, it exhibits excellent mechanical strength, toughness, and low abrasion, and also has excellent feedability to a molding machine during injection molding of pellets of the resin composition.

[0064] <Comparative Example 1> Since the content of component B was below the lower limit, the specific wear rate was large and the tensile strength at break was low.

[0065] <Comparative Example 2> Since the content of component B exceeded the upper limit, the components in the resin composition separated, and a uniform molded product could not be obtained.

[0066] <Comparative Example 3> Since the content of C component was below the lower limit, the specific wear rate was large and the tensile strength at break was low.

[0067] <Comparative Example 4> Since the content of component C exceeded the upper limit, pellet feeding was poor, making continuous molding difficult.

[0068] <Comparative Example 5> Because the content of component D exceeded the upper limit, the molding pressure during injection molding increased, and test pieces of the specified shape could not be obtained.

[0069] <Comparative Example 6> Since the content of component D was below the lower limit, the specific wear rate was large, pellet supply was poor, and continuous molding was difficult.

[0070] <Comparative Example 7> Because component D was different from the epoxy resin represented by formula (1), the molding pressure during injection molding increased, and test pieces of the desired shape could not be obtained.

[0071] <Comparative Example 8> Because component B was not a modified polyethylene resin, the specific wear rate was large and the tensile strength at break was low.

[0072] <Comparative Example 9> Because component C was not a fully aromatic polyamide fiber, the specific wear rate was high and the tensile elongation at break was low.

[0073] <Comparative Example 10> Since component A is not a thermoplastic polyester resin, the tensile strength and elongation at break are low, and pellet feeding is poor, making continuous molding difficult.

Claims

1. A resin composition containing 100 parts by weight of (A) thermoplastic polyester resin (component A), 4 to 25 parts by weight of (B) modified polyethylene resin (component B), 10 to 35 parts by weight of (C) wholly aromatic polyamide fiber (component C), and 0.5 to 8 parts by weight of (D) epoxy resin (component D) represented by the following general formula (1): 【Chemical 1】 (In formula (1), m is an average value and is an integer of 1 or more. R １ and R ２ each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a trifluoromethyl group; each X independently represents a hydrogen atom or a glycidyl group, and at least one of the multiple Xs is a glycidyl group.

2. 2. The resin composition according to claim 1, wherein component B is a modified polyethylene resin having a viscosity average molecular weight of 100,000 to 1,000,000 and modified with at least one compound selected from the group consisting of maleic acid and maleic anhydride.

3. 3. The resin composition according to claim 1, wherein component D is a bisphenol A type epoxy resin or a bisphenol F type epoxy resin having an epoxy equivalent of 1,000 to 10,000 g / eq.

4. 4. The resin composition according to claim 1, wherein component A is a polybutylene naphthalate resin.

5. 5. The resin composition according to claim 1, wherein component C is a wholly aromatic polyamide fiber bundled with at least one sizing agent selected from the group consisting of polyester resins and polyurethane resins.

6. 6. The resin composition according to claim 1, wherein component C is a wholly aromatic polyamide fiber having an average fiber length of 0.5 to 4.0 mm before being added to component A.

7. 7. The resin composition according to claim 1, wherein component C is a para-type wholly aromatic polyamide fiber.

8. A molded article made of the resin composition according to any one of claims 1 to 7.

Images