JP7761468B2 - Semi-aromatic polyamide resin composition and molded article using the same - Google Patents

Description

The present invention relates to a semi-aromatic polyamide resin composition that exhibits excellent mechanical strength, heat resistance, low abrasion, and extrusion processability, and to a molded article made from the same.

In recent years, semi-aromatic polyamides have been used as sliding components such as gears and bearings in automobiles and electrical and electronic equipment. In particular, sliding component applications such as various gears and bearings require low wear when sliding against mating materials, as 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 in harsh environments such as high temperatures and heavy loads, and these components require higher levels of mechanical strength, heat resistance, and low wear than ever before.

As an example of a semi-aromatic polyamide resin composition with sliding properties, Patent Document 1 discloses a resin composition in which polyamide 10T (a polyamide composed of terephthalic acid and 1,10-decanediamine) is mixed with a sliding property-imparting agent, but the resin composition lacks low wear properties under harsh environments such as high loads. Patent Document 2 discloses a resin composition in which MXD6 (a polyamide composed of adipic acid and meta-xylenediamine) is mixed with a sliding property-imparting agent and an aliphatic polyamide, but the low wear properties are insufficient and there is no suggestion that the inclusion of an aliphatic polyamide would improve mechanical strength or heat resistance.

Patent No. 5837377 Patent No. 6827815

The object of the present invention is to provide a semi-aromatic polyamide resin composition that exhibits excellent mechanical strength, heat resistance, low abrasion, and extrusion processability, and to provide a molded article made from the same.

As a result of extensive research into resolving the above-mentioned issues, the inventors discovered that the above objectives could be achieved by blending a semi-aromatic polyamide consisting of a dicarboxylic acid component primarily composed of terephthalic acid and a diamine component primarily composed of 1,10-decanediamine, an aliphatic polyamide, a polyethylene-based sliding property enhancer, and fully aromatic polyamide fibers in specific proportions, resulting in the present invention.

In other words, the above-mentioned object is achieved by a semi-aromatic polyamide resin composition characterized by containing 100 parts by weight of (A) a semi-aromatic polyamide resin (component A) consisting of a dicarboxylic acid component primarily composed of terephthalic acid and an aliphatic diamine component primarily composed of 1,10-decanediamine, 0.1 parts by weight or more but less than 3 parts by weight of (B) an aliphatic polyamide (component B), 1 to 20 parts by weight of (C) a polyethylene-based sliding property imparting material (component C), and 3 to 50 parts by weight of (D) wholly aromatic polyamide fiber (component D).

The details of the present invention are explained below.

(Component A: semi-aromatic polyamide)
Component A of the present invention contains a dicarboxylic acid component and a diamine component as constituent components, with the dicarboxylic acid component being primarily composed of terephthalic acid and the diamine component being primarily composed of 1,10-decanediamine. From the viewpoint of heat resistance, the content of terephthalic acid in the dicarboxylic acid component is preferably 80 mol% or more, and more preferably 100 mol%. From the viewpoint of improving mechanical properties, the content of 1,10-decanediamine in the diamine component is preferably 80 mol% or more, and more preferably 100 mol%. A specific example of Component A is PA10T.

The dicarboxylic acid component may contain a dicarboxylic acid other than terephthalic acid. Examples of dicarboxylic acids other than terephthalic acid include aromatic dicarboxylic acid components such as phthalic acid, isophthalic acid, and naphthalenedicarboxylic acid, aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. The amount of dicarboxylic acids other than terephthalic acid is preferably 20 mol % or less of the total number of moles of raw material monomers, and more preferably, they are substantially free of dicarboxylic acids other than terephthalic acid.

The diamine component may contain diamines other than 1,10-decanediamine. Examples of other diamines include aliphatic diamines such as 1,2-ethanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, and 1,15-pentadecanediamine; alicyclic diamines such as cyclohexanediamine; and aromatic diamines such as xylylenediamine and benzenediamine. The amount of other diamines other than the 1,10-decanediamine component is preferably 20 mol % or less of the total number of moles of the raw material monomers, and more preferably substantially none.

Component A in the present invention preferably has a melting point higher than 300°C, which may further improve heat resistance. When it has multiple melting points or when two or more types of semi-aromatic polyamides are used, it may have a melting point of 300°C or lower.

The melting point of component A in this invention refers to the temperature of the endothermic peak that appears when approximately 10 mg of semi-aromatic polyamide pellets are sampled and, using a differential scanning calorimeter, cooled from the molten state to 20°C at a rate of 20°C/min under a nitrogen atmosphere, held there for 5 minutes, and then heated again at a rate of 20°C/min. However, if two or more endothermic peaks are detected, the peak with the highest temperature is taken as the melting point.

Component A can be produced using conventionally known methods such as thermal polymerization and solution polymerization. Thermal polymerization is preferred due to its industrial advantages. Examples of thermal polymerization include a process comprising step (i) of obtaining a reaction product from a dicarboxylic acid component and a diamine component, and step (ii) of polymerizing the resulting reaction product.

Step (i) can be achieved, for example, by mixing a dicarboxylic acid powder with a monocarboxylic acid, heating the mixture to a temperature above the melting point of the diamine but below the melting point of the dicarboxylic acid, and then adding the diamine to the dicarboxylic acid powder and monocarboxylic acid at this temperature, substantially without adding water, so as to maintain the dicarboxylic acid in powder form. Alternatively, another method involves stirring and mixing a suspension of molten diamine and solid dicarboxylic acid to obtain a mixture, which is then subjected to a reaction between the dicarboxylic acid, diamine, and monocarboxylic acid to form a salt and a polymerization reaction of the resulting salt to form an oligomer at a temperature below the melting point of the resulting semi-aromatic polyamide, thereby obtaining a mixture of the salt and oligomer. In this case, crushing can be performed during the reaction, or the mixture can be removed after the reaction and crushed. The former method is preferred for step (i), as it allows for easier control of the shape of the reaction product.

Step (ii) can be achieved, for example, by solid-state polymerization of the reaction product obtained in step (i) at a temperature below the melting point of the final semi-aromatic polyamide, thereby increasing the molecular weight to a predetermined level and obtaining a semi-aromatic polyamide. Solid-state polymerization is preferably carried out in a stream of inert gas such as nitrogen at a polymerization temperature of 180 to 270°C for a reaction time of 0.5 to 10 hours.

The reaction apparatus for steps (i) and (ii) is not particularly limited, and any known apparatus may be used. Steps (i) and (ii) may be performed in the same apparatus or in different apparatuses.

In producing component A, a polymerization catalyst may be used to increase the efficiency of polymerization. Examples of polymerization catalysts include phosphoric acid, phosphorous acid, hypophosphorous acid, and salts thereof. It is generally preferable to add the polymerization catalyst in an amount of 2 mol% or less based on the total monomers constituting the semi-aromatic polyamide.

(Component B: Aliphatic polyamide)
Examples of aliphatic polyamides used as component B in the present invention include polyε-capramide (PA6), polytetramethylene adipamide (PA46), polyhexamethylene adipamide (PA66), polyhexamethylene sebacamide (PA610), polyhexamethylene dodecamide (PA612), polyundecamethylene adipamide (PA116), polyundecanamide (PA11), polydodecanamide (PA12), and polyamide copolymers containing at least two different polyamide components, or mixtures thereof. Among these, polyamides having a structural unit with 6 or fewer carbon atoms are preferred, with PA6 (nylon 6) and PA66 (nylon 66) being preferred from an economical standpoint. The use of aliphatic polyamides can improve the wear resistance, mechanical strength, and heat resistance of molded articles.

The relative viscosity of the aliphatic polyamide is not particularly limited and may be set appropriately depending on the purpose. For example, to obtain a thermoplastic resin composition that is easy to mold, the aliphatic polyamide preferably has a relative viscosity of 1.9 to 4.0, and more preferably 2.0 to 3.5. If the relative viscosity of the aliphatic polyamide is less than 1.9, some molded articles may lack toughness, resulting in reduced mechanical properties. Furthermore, if the relative viscosity of the aliphatic polyamide exceeds 4.0, the thermoplastic resin composition may be difficult to mold, and the resulting molded article may have poor appearance.

The content of Component B is 0.1 to 3 parts by weight, preferably 0.3 to 2.5 parts by weight, and more preferably 0.5 to 2 parts by weight, per 100 parts by weight of Component A. If the content is less than 0.1 part by weight, the amount of wear during sliding increases, and mechanical strength and heat resistance decrease. On the other hand, if the content is 3 parts by weight or more, the amount of wear during sliding increases.

(Component C: Polyethylene-based sliding property imparting material)
The polyethylene-based sliding property imparting agent used as component C in the present invention can be any known agent. The use of a polyethylene-based sliding property imparting agent can improve the low wear and mechanical strength of molded articles. Examples of polyethylenes used as starting materials in producing polyethylene-based sliding property imparting agents include high-density polyethylene, low-density polyethylene, and ultra-high-molecular-weight polyethylene each having a viscosity-average molecular weight of several tens of thousands or more, polyethylene wax having a viscosity-average molecular weight of several tens of thousands or less, and mixtures of one or more of these. Various conventionally known methods can be used to modify polyethylene, including, for example, 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. Use of these preferred modified polyethylene resins may further improve the mechanical strength and low wear properties of molded articles.

The viscosity average molecular weight (Mv) of component C is preferably in the range of 100,000 to 1,000,000, more preferably 200,000 to 900,000, and particularly preferably 300,000 to 800,000. By using a polyethylene resin in this range, the mechanical strength and low abrasion properties of the molded article may be further improved. The viscosity average molecular weight of component C is calculated from the following general formula (1) using the intrinsic viscosity [η] measured in decacarboxylic acid solvent at 135°C:
Mv=5.37×10 ⁴ [η] ^1.37 ...(1)

The content of Component C is 1 to 20 parts by weight, preferably 3 to 18 parts by weight, and more preferably 5 to 15 parts by weight, per 100 parts by weight of Component A. If the content is less than 1 part by weight, the amount of wear during sliding increases and the mechanical strength decreases. If the content exceeds 20 parts by weight, extrusion processability decreases.

(Component D: fully aromatic polyamide fiber)
The wholly aromatic polyamide fiber used as component D in the present invention may be any fiber that falls into the category of so-called wholly aromatic aramid fibers. By using wholly aromatic polyamide fibers, it is possible to ensure both the mechanical strength and heat resistance required for sliding members and to exhibit excellent low wear properties. Examples of wholly aromatic aramid fibers include meta-aramid fibers and para-aramid fibers, and among these, para-aramid fibers are preferred.

The wholly aromatic polyamide constituting the fibers 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, can also be added to the one or more aromatic diamines and one or more aromatic dicarboxylic acids. The wholly aromatic polyamide may be either para- or meta-type, with the para-type being 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. As the aromatic dicarboxylic acid halide, acid chlorides are particularly preferred, such as terephthalic acid chloride, 2,6-naphthalenedicarboxylic acid chloride, 4,4'- Examples include diphenyldicarboxylic acid chloride and 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. Furthermore, when using aromatic dicarboxylic acids, examples 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, and nitro groups. Furthermore, the structure of a wholly aromatic polyamide preferred in the present invention is one whose main skeleton is represented by the following formula:

(wherein Ar ₁ and Ar ₂ represent at least one aromatic residue selected from the group consisting of the following general formulae [I] to [IV]. Ar ₁ and Ar ₂ may be the same or different. In addition, these aromatic residues may have some of their hydrogen atoms substituted with halogen atoms or lower alkyl groups.)

Among these, when the sum of Ar ₁ and Ar ₂ is taken as 100 mol %, it is preferable that 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 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 %.

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 an inorganic salt may be added as a solubilizing agent to improve solubility. Examples of such inorganic salts include lithium chloride and calcium chloride.

The polymerization solvent or redissolution solvent is generally a known aprotic organic polar solvent, such as 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, or dimethyl sulfoxide. Furthermore, redissolution solvents include strong acids such as concentrated sulfuric acid and methanesulfonic acid.

There are no particular restrictions on the degree of polymerization of wholly aromatic polyamides, but a higher degree of polymerization is preferable if they are soluble in a solvent. When solution-polymerizing wholly aromatic polyamides, the acid component and diamine component are reacted in a substantially equimolar ratio, but either component can be used in excess to control the degree of polymerization. Furthermore, monofunctional acid components and amine components can be used as end-capping agents.

When forming wholly aromatic polyamide into fibers, a method of wet forming a wholly aromatic polyamide dope is typically used. This can be done 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, but a good solvent is usually added to adjust the coagulation rate so that the solvent in the wholly aromatic polyamide dope does not escape too quickly, causing defects in the wholly aromatic polyamide fiber. It is generally 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 to poor solvent is preferably 15/85 to 40/60, depending on the solubility and coagulation properties of the wholly aromatic polyamide.

Such wholly aromatic polyamide fibers are effective whether bundled or not, but bundled fibers are easier to handle and are therefore preferred. Examples of binders for bundling include polyester resins, polyurethane resins, and polyethersulfone resins, with polyester resins being preferred. In the present invention, such wholly aromatic polyamide fibers can be used alone or as a mixture of two or more types.

The form of such wholly aromatic polyamide fibers is not particularly limited, and any form can be used, but from the perspective of handleability during resin composition production, it is preferable that the fibers be twisted. Using a fiber bundle with a high twist number may stabilize the supply of wholly aromatic polyamide fibers to the extruder. The preferred twist number for 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.

The content of Component D is 3 to 50 parts by weight, preferably 10 to 40 parts by weight, more preferably 15 to 30 parts by weight, and even more preferably 18 to 27 parts by weight, per 100 parts by weight of Component A. If the content of Component D exceeds 50 parts by weight, extrusion processability decreases. On the other hand, if the content is less than 3 parts by weight, the amount of wear during sliding increases, and mechanical strength and heat resistance decrease.

(Regarding other additives)
Furthermore, 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 D, flame retardants, colorants, light stabilizers, heat stabilizers, antistatic agents, antiblocking agents, lubricants other than component C, dispersants, flow modifiers, and crystal nucleating agents, as needed, within the scope of the present invention.

(Production of 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 controlled stirring 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.

(Regarding molded products)
The resin composition of the present invention obtained as described above can be injection molded or extruded to produce various products. Furthermore, it is also possible to directly mold sheets, films, profile extrusions, and injection-molded products from the melt-kneaded resin in an extruder without first passing through pellets. 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 supercritical fluid injection), insert molding, in-mold coating molding, adiabatic mold molding, rapid heating and cooling mold molding, two-color molding, sandwich molding, and ultra-high-speed injection molding, depending on the purpose. The advantages of these molding methods are widely known. Molding can be performed using either a cold runner or hot runner system. The resin composition of the present invention can also be extruded to produce various profile extrusions and sheets. In extrusion molding, molded products can be obtained by extruding a round rod and then cutting it into a disk, or by extruding a thick sheet and then punching it into a desired shape.

The present invention provides a semi-aromatic polyamide resin composition and molded articles made therefrom that exhibit excellent mechanical strength, heat resistance, low abrasion, and extrusion processability. Molded articles made from the resin composition of the present invention can be suitably used for sliding components in the electrical and electronics, semiconductor, automotive, industrial machinery, office automation equipment, and construction fields, for example.

The embodiments for implementing the present invention summarize the preferred ranges of each of the above-mentioned requirements, and representative examples are described in the examples below. Of course, the present invention is not limited to these embodiments.

The following examples illustrate how the present invention can be implemented. Physical properties were evaluated using the following methods.

[Evaluation of Resin Composition]
The stability during extrusion was measured as an evaluation of extrusion processability, the specific wear rate as an evaluation of low wear, the tensile strength as an evaluation of mechanical strength, and the deflection temperature under load as an evaluation of heat resistance, all of which were measured by the methods described below.

(1) Extrusion Processability The stability during extrusion was evaluated according to the following criteria.
The strands are stable during extrusion: ◯ The strands are unstable during extrusion, making pelletization difficult: ×

(2) Specific Wear Rate The pellets obtained by the method described below were dried at 130 ° C. for 6 hours and then molded in accordance with JIS K7218A method using an injection molding machine (Toshiba Machine Co., Ltd., EC130SXII-4Y) at a cylinder temperature of 330 ° C. and a mold temperature of 130 ° C. to obtain a hollow cylindrical test piece having an outer diameter of 25.6 mm, an inner diameter of 20 mm, and a height of 15 mm. The test piece was slid against a test piece of similar shape made of carbon steel (S45C) in accordance with JIS K7218A method using a friction and wear tester (EFM-3-G, manufactured by Orientec Co., Ltd.) under conditions of 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 piece 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 method. The test was carried out three times, and the average value was taken as the specific wear rate of the composition. The specific wear rate must be 2.0×10 ⁻⁶ mm ³ /N·m or less.

(3) Tensile Break Strength Pellets obtained by the method described below were dried at 130°C for 6 hours, and then test pieces were prepared using an injection molding machine (EC130SXII-4Y, manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 330°C and a mold temperature of 130°C. Tensile tests were carried out in accordance with ISO 527-1 and 527-2 at a test temperature of 23°C and a test speed of 5 mm/min to measure the tensile break strength. The tensile break strength must be 70 MPa or more.

(4) Heat deflection temperature (HDT)
The pellets obtained by the method described below were dried at 130°C for 6 hours, and then test specimens were prepared using an injection molding machine (EC130SXII-4Y, manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 330°C and a mold temperature of 130°C, and the deflection temperature under load was measured in accordance with ISO 75-1 and 75-2. Heat resistance is required to be 120°C or higher under a load of 1.8 MPa.

[Examples 1-11, Comparative Examples 1-6]
According to the amounts shown in Tables 1 and 2, component A, component B, component C, and other components were separately fed into a twin-screw extruder through the first feed port. Here, the first feed port refers to the feed port at the base. Component D was separately fed through the second feed port using a side feeder. For extrusion, a vented twin-screw extruder with a diameter of 30 mm (TEX30α-31.5BW-3V, manufactured by The Japan Steel Works, Ltd.) was used, and pellets were obtained by melt-kneading at a screw rotation speed of 200 rpm, a discharge rate of 20 kg/h, and a vent vacuum of 3 kPa. The extrusion temperature was 330°C.

(Component A)
A-1: Semi-aromatic polyamide: PA10T (manufactured by Unitika Ltd.: Xecot XP500)
(B component)
B-1: Aliphatic polyamide: PA6 (manufactured by Ube Industries, Ltd.: UBE Nylon 1011FB)
B-2: Aliphatic polyamide: PA66 (manufactured by Ube Industries, Ltd.: UBE Nylon 2015B)

(C component)
C-1: Maleic anhydride-modified polyethylene resin obtained in Production Example 1 <Production Example 1>
100 parts by weight of a polyethylene resin mixture consisting of 15% by weight of ultra-high molecular weight polyethylene (Hi-Zex Million 630M manufactured by Mitsui Chemicals, Inc.) having an intrinsic viscosity of 31 dl/g measured in decaphosphoric acid solvent at 135 ° C. and 85% by weight of polyethylene (Hi-Zex 2200J manufactured by Prime Polymer Co., Ltd.) having an intrinsic viscosity of 2 dl/g measured in decaphosphoric acid solvent at 135 ° C., 1 part by weight of maleic anhydride and 0.07 parts by weight of organic peroxide (Perhexine-25B manufactured by NOF Corporation) were mixed in a Nauta mixer, and the resulting mixture was melt-kneaded in a single-screw extruder (EXT40 m/m extruder manufactured by Isuzu Chemical Engineering Co., Ltd.) set at 250 ° C. to obtain component C-1. The intrinsic viscosity [η] of the resulting modified polyethylene resin measured in decaphosphoric acid at 135 ° C. was 5.5 dl/g, and the viscosity average molecular weight Mv was 550,000.

C-2: Polyethylene resin obtained in Production Example 2 <Production Example 2>
100 parts by weight of a polyethylene resin mixture consisting of 15% by weight of ultra-high molecular weight polyethylene (Hi-Zex Million 630M manufactured by Mitsui Chemicals, Inc.) having an intrinsic viscosity of 31 dl/g measured in decaphosphoric acid solvent at 135 ° C. and 85% by weight of polyethylene (Hi-Zex 2200J manufactured by Prime Polymer Co., Ltd.) having an intrinsic viscosity of 2 dl/g measured in decaphosphoric acid solvent at 135 ° C. was mixed in a Nauta mixer, and the resulting mixture was melt-kneaded in a single-screw extruder (EXT40 m/m extruder manufactured by Isuzu Chemical Engineering Co., Ltd.) set at 250 ° C. to obtain component C-2. The intrinsic viscosity [η] of the resulting polyethylene resin measured in decaphosphoric acid at 135 ° C. was 5.5 dl/g, and the viscosity average molecular weight Mv was 550,000.

C-3: Oxidized polyethylene wax: Hiwax 310MP (product name) (Mitsui Chemicals, Inc., viscosity average molecular weight approximately 3,000)

(D component)
D-1: Wholly aromatic polyamide fiber: T322EH (product name) (manufactured by Teijin Limited, para-aramid fiber, major diameter 12 μm, average fiber length 3 mm, polyester resin sizing agent, twist number 245 times/m)
D-2: Wholly aromatic polyamide fiber: T322UR (product name) (manufactured by Teijin Limited, para-aramid fiber, major diameter 12 μm, average fiber length 3 mm, polyurethane resin sizing agent, twist number 60 times/m)

<Examples 1 to 11>
Since the resin composition was within the scope of the present invention, it was found to have excellent mechanical strength, heat resistance and low abrasion.

<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 and heat resistance were low.

<Comparative Example 2>
Since the content of component B exceeded the upper limit, the specific wear rate was large.

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

<Comparative Example 4>
Since the content of component C exceeded the upper limit, pelletization was not possible.

Comparative Example 5
Since the content of component D was below the lower limit, the specific wear rate was large, and the tensile strength at break and heat resistance were low.

<Comparative Example 6>
Since the content of component D exceeded the upper limit, pelletization was not possible.

Claims (3)

A semi-aromatic polyamide resin composition comprising 100 parts by weight of (A) a semi-aromatic polyamide (component A) comprising a dicarboxylic acid component having terephthalic acid as a main component and an aliphatic diamine component having 1,10-decanediamine as a main component, and containing 0.1 parts by weight or more but less than 3 parts by weight of (B) nylon 6 and/or nylon 66 (component B), 1 to 20 parts by weight of (C) a polyethylene-based sliding property imparting material (component C), and 3 to 50 parts by weight of (D) wholly aromatic polyamide fiber (component D). 2. The semi-aromatic polyamide resin composition according to claim 1, wherein component C 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. A molded article made from the semi-aromatic polyamide resin composition according to claim 1 or 2 .