Polyamide resin composition, molded body made from the same, and vehicle-mounted camera parts

Abstract

A polyamide resin composition which contains 100 parts by mass of (A) a semiaromatic polyamide and from 70 parts by mass to 250 parts by mass of (B) a filler, and which is characterized in that the linear expansion coefficient of an injection molded body thereof is 70 × 10-6 (1 / °C) or less at 80°C in a direction that is perpendicular to the flowing direction of the resin during the injection molding.

Description

[Technical Field]

[0001] The present invention relates to a polyamide resin composition, a molded article made thereof, and an in-vehicle camera part. [Background technology]

[0002] In recent years, vehicles have increasingly been equipped with on-board cameras to enhance driving safety. Of the components of on-board cameras, the camera housing and camera barrel are primarily made of resin materials. The camera housing is a case that houses the structural components of the camera equipment. The camera barrel is a holder that is located inside the camera housing and holds the camera lens. Both components are required to have excellent mechanical properties to protect and hold the camera and lens. Furthermore, both components are required to have excellent dimensional stability to prevent the assembled lens from warping, even when exposed to high temperatures.

[0003] Patent Document 1 discloses that by adding 0.002 to 0.5 mass % of a plate-like filler to a polyamide resin based on the entire polyamide resin composition, the linear expansion coefficient of the resulting molded article in the flow direction (MD) of the resin during molding is reduced. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-210544 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the polyamide resin composition described in Patent Document 1 uses polyamide 66, the resulting molded article has insufficient improvement in dimensional stability, and in particular has a problem in that the linear expansion coefficient in the direction (TD) perpendicular to the flow direction (MD) of the resin during molding is large. Molded articles used in car-mounted camera parts and the like are required to have a small coefficient of linear expansion not only in the direction of flow (MD) of the resin during molding, but also in the transverse direction (TD).

[0006] The present invention aims to provide a polyamide resin composition that can give a molded article having excellent dimensional stability in both the flow direction (MD) and the transverse direction (TD) while also having excellent mechanical properties. [Means for solving the problem]

[0007] As a result of extensive research to solve the above problems, the inventors discovered that the above object can be achieved by blending a specific amount of filler with a semi-aromatic polyamide, and thus arrived at the present invention.

[0008] The polyamide resin composition of the present invention containing 100 parts by mass of a semi-aromatic polyamide (A) and 70 to 250 parts by mass of a filler (B) is The linear expansion coefficient of the injection-molded body at 80°C in the direction perpendicular to the direction of resin flow during injection molding is 70 x 10 -6 (1 / °C) or less. According to the polyamide resin composition of the present invention, it is preferred that the length of burrs generated in the injection molded article at positions corresponding to the gas vent portions of the mold during injection molding is 150 μm or less. According to the polyamide resin composition of the present invention, the filler (B) preferably comprises a plate-like filler and a fibrous filler. According to the polyamide resin composition of the present invention, the mass ratio of the plate-like filler to the fibrous filler (plate-like filler / fibrous filler) is preferably 50 / 50 to 90 / 10. According to the polyamide resin composition of the present invention, it is preferred that the plate-like filler is glass flakes and the fibrous filler is glass fiber. According to the polyamide resin composition of the present invention, it is preferred that the plate-like filler is glass flakes and the fibrous filler is carbon fiber. The polyamide resin composition of the present invention preferably further contains 20 to 110 parts by mass of a polyphenylene ether (C). The molded article of the present invention is obtained by molding the above polyamide resin composition. The vehicle-mounted camera part of the present invention is made of the above-mentioned molded article. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a polyamide resin composition that can give a molded article that has excellent mechanical properties and dimensional stability in both the flow direction (MD) and the transverse direction (TD). [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an explanatory diagram of a method for evaluating water vapor permeation rate. DETAILED DESCRIPTION OF THE INVENTION

[0011] The polyamide resin composition of the present invention contains a semi-aromatic polyamide (A) and a filler (B).

[0012] (Semi-aromatic polyamide (A)) The semi-aromatic polyamide (A) used in the present invention is composed of an aromatic dicarboxylic acid component and an aliphatic diamine component.

[0013] The aromatic dicarboxylic acid component preferably contains terephthalic acid as a main component. In the present invention, "containing terephthalic acid as a main component" means that the aromatic dicarboxylic acid component contains 90 mol% or more of terephthalic acid. The content of terephthalic acid in the aromatic dicarboxylic acid component is preferably 95 mol% or more, more preferably 100 mol%. If the aromatic dicarboxylic acid component does not contain terephthalic acid as a main component, the resulting molded article may have poor dimensional stability.

[0014] The aromatic dicarboxylic acid component may contain an aromatic dicarboxylic acid other than terephthalic acid, such as isophthalic acid or naphthalenedicarboxylic acid.

[0015] The aliphatic diamine component preferably contains an aliphatic diamine having 8 or more carbon atoms as a main component. In the present invention, "containing an aliphatic diamine having 8 or more carbon atoms as a main component" means that the aliphatic diamine component contains 90 mol % or more of aliphatic diamines having 8 or more carbon atoms. The content of aliphatic diamines having 8 or more carbon atoms in the aliphatic diamine component is preferably 95 mol % or more, and more preferably 100 mol %. If the aliphatic diamine component does not contain an aliphatic diamine having 8 or more carbon atoms as a main component, the processability of the semi-aromatic polyamide (A) may be reduced. Examples of aliphatic diamines having 8 or more carbon atoms include 1,8-octanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, 1,10-decanediamine, and 1,12-undecanediamine. Among these, 1,10-decanediamine is more preferred because the semi-aromatic polyamide (A) has an excellent balance between heat resistance and processability and has reduced water absorption and moisture permeability.

[0016] The aliphatic diamine component may contain an aliphatic diamine other than the aliphatic diamine having 8 or more carbon atoms. Examples of the other aliphatic diamine include 1,2-ethanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 2-methyl-1,5-pentanediamine, 1,6-hexanediamine, and 1,7-heptanediamine.

[0017] The semi-aromatic polyamide (A) may contain dicarboxylic acids other than aromatic dicarboxylic acids; diamines other than aliphatic diamines; lactams; and ω-aminocarboxylic acids, provided that the effects of the present invention are not impaired. Examples of dicarboxylic acids other than aromatic dicarboxylic acids include 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 1,4-cyclohexanedicarboxylic acid. Examples of diamines other than aliphatic diamines include alicyclic diamines such as 1,4-cyclohexanediamine; and aromatic diamines such as metaxylylenediamine and paraxylylenediamine. Examples of lactams include caprolactam and laurolactam. Examples of ω-aminocarboxylic acids include aminocaproic acid and 11-aminoundecanoic acid.

[0018] The semi-aromatic polyamide (A) may contain a monocarboxylic acid component in addition to the dicarboxylic acid component and diamine component. Examples of the monocarboxylic acid component include aliphatic monocarboxylic acids such as stearic acid, octanoic acid, nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, and behenic acid; alicyclic monocarboxylic acids such as 4-ethylcyclohexanecarboxylic acid, 4-hexylcyclohexanecarboxylic acid, and 4-laurylcyclohexanecarboxylic acid; and aromatic monocarboxylic acids such as 4-ethylbenzoic acid, 4-hexylbenzoic acid, 4-laurylbenzoic acid, alkylbenzoic acids, 1-naphthoic acid, and 2-naphthoic acid. Among these, monocarboxylic acids having a molecular weight of 140 or more are preferred because they improve the molding processability of the semi-aromatic polyamide (A), and stearic acid is more preferred because of its high versatility. The molecular weight of the monocarboxylic acid refers to the molecular weight of the monocarboxylic acid used as a raw material during polymerization. The content of the monocarboxylic acid component is preferably 0.3 to 5.0 mol %, more preferably 0.6 to 4.0 mol %, and even more preferably 1.0 to 3.5 mol %, based on all monomers constituting the semi-aromatic polyamide. When the content of the monocarboxylic acid component is 0.3 to 5.0 mol %, the molding processability of the semi-aromatic polyamide (A) is improved without significantly reducing the molecular weight.

[0019] The semi-aromatic polyamide (A) can be produced by conventionally known methods such as thermal polymerization and solution polymerization. Among these, thermal polymerization is preferred because of its industrial advantages. Examples of thermal polymerization include a method comprising a step (i) of obtaining a reaction product from a dicarboxylic acid component and a diamine component, and a step (ii) of polymerizing the obtained reaction product.

[0020] Step (i) can be achieved, for example, by first heating a dicarboxylic acid powder 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 at this temperature, substantially without adding water, so as to maintain the dicarboxylic acid powder 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 and the diamine 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 semi-aromatic polyamide to be ultimately produced, thereby obtaining a mixture of the salt and the oligomer. In this case, crushing can be carried out 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.

[0021] In step (ii), for example, the reaction product obtained in step (i) is polymerized in a solid state at a temperature below the melting point of the resulting semi-aromatic polyamide to obtain a semi-aromatic polyamide. The solid state polymerization is preferably carried out at a polymerization temperature of 180 to 270°C for a reaction time of 0.5 to 10 hours in a stream of an inert gas such as nitrogen.

[0022] The reaction apparatus for step (i) and step (ii) is not particularly limited, and any known apparatus may be used. Step (i) and step (ii) may be performed in the same apparatus or in different apparatuses.

[0023] The heating method in the thermal polymerization method is not particularly limited, but examples thereof include a method of heating a reaction vessel with a medium such as water, steam, or thermal oil, a method of heating a reaction vessel with an electric heater, and a method of utilizing frictional heat accompanying the movement of the contents, such as heat generated by stirring. These methods may also be combined.

[0024] In the production of the semi-aromatic polyamide (A), a polymerization catalyst may be used to increase the efficiency of polymerization. Examples of the polymerization catalyst include phosphoric acid, phosphorous acid, hypophosphorous acid, and salts thereof. The amount of the polymerization catalyst added is usually preferably 2 mol % or less based on the total monomers constituting the semi-aromatic polyamide (A).

[0025] (Filling material (B)) The filler (B) used in the present invention may be made of either an organic compound or an inorganic compound. The filler (B) may be in the form of, for example, a plate, fiber, granule, or amorphous shape, and among these, the plate, fiber, or granule shapes are preferred because they provide a molded product with excellent dimensional stability. The filler (B) may be used alone or in combination of two or more types.

[0026] In the resin composition of the present invention, the content of filler (B) must be 70 to 250 parts by mass, preferably 80 to 200 parts by mass, and more preferably 90 to 150 parts by mass, per 100 parts by mass of semi-aromatic polyamide (A). When the content of filler (B) in the resin composition is 70 to 250 parts by mass, the shrinkage of the semi-aromatic polyamide due to temperature changes is suppressed, thereby reducing the linear expansion coefficient of the resulting molded article and further suppressing the generation of flash in the position corresponding to the gas vent of the mold. When the content of filler (B) is less than 70 parts by mass, the linear expansion coefficient of the resulting molded article is high. On the other hand, when the content of filler (B) exceeds 250 parts by mass, melt-kneading with the aromatic polyamide resin becomes difficult, and pellets of the resin composition may not be produced.

[0027] Examples of the plate-like filler include glass flakes, talc, mica, and scaly graphite. Examples of mica include muscovite, fluorphlogopite, and tetrasilicic mica. Among these, glass flakes and mica are preferred because of their versatility.

[0028] Examples of fibrous fillers include carbon fibers, glass fibers, silica fibers, silica-alumina fibers, zirconia fibers, alumina fibers, silicon carbide fibers, metal fibers (such as stainless steel fibers and aluminum oxide fibers), ceramic fibers, boron whiskers, zinc oxide whiskers, asbestos, wollastonite, potassium titanate whiskers, calcium carbonate whiskers, aluminum borate whiskers, magnesium sulfate whiskers, acicular titanium oxide, sepiolite, xonotlite, milled fibers, and cut fibers. Among these, glass fibers and wollastonite are preferred due to their versatility. The surface of the fibrous filler is preferably treated with an aminosilane coupling agent or epoxy resin to improve dispersibility in the semi-aromatic polyamide (A). In particular, surface treatment with an aminosilane coupling agent is more preferred to improve mechanical properties and adhesion to adhesives such as epoxy resins.

[0029] Examples of granular fillers include alumina, titanium oxide, boron nitride, silicon carbide, and calcium carbonate, with calcium carbonate being preferred due to its versatility.

[0030] In the present invention, the filler (B) preferably comprises a plate-like filler and a fibrous filler. The mass ratio of the plate-like filler to the fibrous filler (plate-like filler / fibrous non-filler) is preferably 50 / 50 to 90 / 10, and more preferably 55 / 45 to 85 / 15. By having the mass ratio be 50 / 50 to 90 / 10, the linear expansion coefficient of the obtained molded article can be further reduced, and the mechanical properties can be improved. When the filler (B) is composed of a plate-like filler and a fibrous filler, it is preferable to use glass flakes as the plate-like filler and glass fiber or carbon fiber as the fibrous filler, in terms of improving dimensional stability in both the flow direction (MD) and the transverse direction (TD). When the filler (B) is partially or entirely composed of carbon fiber, the carbon fiber content is preferably less than 100 parts by mass per 100 parts by mass of the semi-aromatic polyamide (A). If the carbon fiber content of the polyamide resin composition is 100 parts by mass or more, pellets may not be obtained.

[0031] (Polyphenylene ether (C)) The polyamide resin composition of the present invention preferably further contains a polyphenylene ether (C). By containing the polyphenylene ether (C) in the resin composition, the length of flash generated at a position corresponding to the gas vent of the mold during injection molding can be further shortened in the obtained molded article, and the water vapor permeation rate can also be reduced. When the polyamide resin composition of the present invention contains polyphenylene ether (C), the content thereof is preferably 20 to 110 parts by mass, more preferably 25 to 100 parts by mass, per 100 parts by mass of the semi-aromatic polyamide (A). Commercially available polyphenylene ethers (C) include, for example, Noryl PPO640 (manufactured by SABIC) and Iupiace PX-100F (manufactured by Mitsubishi Engineering Plastics Corporation).

[0032] (additives, other resins) The polyamide resin composition of the present invention may contain additives such as fillers other than the filler (B), ultraviolet absorbers, light stabilizers, heat stabilizers, antioxidants, release agents, lubricants, colorants, antistatic agents, and crystal nucleating agents, as well as other thermoplastic resins such as amorphous polyamides other than the semi-aromatic polyamide (A) and polyphenylene ether (C), as long as the effects of the present invention are not impaired. When an additive is contained, the content thereof is preferably 2% by mass or less of the polyamide resin composition. When the other thermoplastic resin is contained, the content thereof is preferably 50% by mass or less of the polyamide resin composition.

[0033] (characteristic) The polyamide resin composition of the present invention has excellent mechanical properties, and therefore the resulting molded article can have a bending strength of 100 MPa or more, preferably 120 MPa or more, and more preferably 140 MPa or more, and a bending modulus of elasticity of 10 GPa or more, and preferably 12 GPa or more.

[0034] Furthermore, the injection-molded article obtained from the polyamide resin composition of the present invention has excellent dimensional stability in both the flow direction (MD) of the resin during injection molding and the direction perpendicular thereto (TD). Therefore, the linear expansion coefficient at 80°C in both the MD and TD directions is 70 × 10 -6 (1 / °C) or less, and preferably 60 × 10 -6 (1 / °C) or less, and more preferably 45 × 10 -6 (1 / °C) or less. At 80°C in either the flow direction (MD) or the transverse direction (TD), -6A linear expansion coefficient of (1 / °C) or less can be achieved by the resin composition constituting the molded body containing a plate-like filler such as glass flakes or mica, a granular filler, or a plate-like filler and a fibrous filler in a specific mass ratio.

[0035] Furthermore, the injection-molded article obtained from the polyamide resin composition of the present invention can have a burr length generated at a position corresponding to a gas vent portion of a mold during injection molding of 180 μm or less, preferably 150 μm or less, and more preferably 135 μm or less. Generally, the generation of burrs during molding reduces production efficiency, so a shorter burr length is preferred.

[0036] The polyamide resin composition of the present invention also has excellent low water absorption and low moisture permeability. Water absorption and moisture permeability have a significant effect on dimensional stability, and generally, the lower the water absorption and moisture permeability, the better the dimensional stability. Furthermore, when used as a component material for an in-vehicle camera, the lower the water absorption and moisture permeability, the more effectively the lens fogging can be suppressed. In the present invention, the resin composition is molded into a plate-shaped molded product having a thickness of 1 mm, and the amount of water vapor permeated in an atmosphere at 65°C can be reduced to 150 mg or less, preferably 130 mg or less, and more preferably 120 mg or less.

[0037] (Manufacturing method) In the present invention, the method for producing the resin composition by blending the components constituting the resin composition is not particularly limited, but it is preferably produced by a melt-kneading method. Examples of the melt-kneading method include methods using a batch kneader such as a Brabender, a Banbury mixer, a Henschel mixer, a helical rotor, a roll, a single-screw extruder, a twin-screw extruder, etc. The melt-kneading temperature is selected from a range in which the semi-aromatic polyamide (A) melts but does not decompose, and is usually preferably (Tm-20°C) to (Tm+50°C), where Tm is the melting point of the semi-aromatic polyamide (A).

[0038] Examples of methods for processing the polyamide resin composition of the present invention include a method in which the molten mixture is extruded into strands and then pelletized; a method in which the molten mixture is hot-cut or underwater-cut into pellets; a method in which the molten mixture is extruded into a sheet and then cut; and a method in which the molten mixture is extruded into a block and then crushed into a powder.

[0039] (Molded body) Methods for molding the polyamide resin composition of the present invention include, for example, injection molding, extrusion molding, blow molding, and sinter molding. Injection molding is preferred due to its significant improvement in mechanical properties and moldability. The injection molding machine is not particularly limited, but examples include a screw-inline injection molding machine or a plunger injection molding machine. The polyamide resin composition is heated and melted in the cylinder of the injection molding machine, measured for each shot, injected into a mold in a molten state, cooled and solidified into a predetermined shape, and then removed from the mold as a molded product. The resin temperature during injection molding is preferably equal to or higher than Tm, and more preferably lower than (Tm + 50°C), where Tm is the melting point of the semi-aromatic polyamide (A). It is preferable that the polyamide resin composition pellets used for heating and melting the polyamide resin composition are sufficiently dried. If the polyamide resin composition pellets contain a high moisture content, the resin may foam in the cylinder of the injection molding machine, making it difficult to obtain an optimal molded product. The moisture content of the polyamide resin composition pellets used in injection molding is preferably less than 0.3 parts by mass, and more preferably less than 0.1 parts by mass, based on 100 parts by mass of the polyamide resin composition.

[0040] The molded articles obtained from the polyamide resin composition of the present invention have excellent mechanical properties and dimensional stability in both the flow direction (MD) and the transverse direction (TD), and therefore can be suitably used for vehicle-mounted camera parts, particularly lens barrels and housings. They can also be used for electrical and electronic connectors, switches, aluminum electrolytic capacitor terminal blocks, actuator parts, LED reflectors, sensors, sockets, jacks, fuse holders, relays, coil bobbins, resistors, IC and LED housings, etc. [Example]

[0041] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0042] A.Measurement method (1) Melting point of semi-aromatic polyamide (A) A pellet of the thoroughly dried semi-aromatic polyamide (A) was shaved, and 10 mg of the shavings were measured using a PerkinElmer DSC-7 differential scanning calorimeter under a nitrogen atmosphere under the following conditions. Heat up to 350°C at a rate of 20°C / min (1st scan) → Hold at 350°C for 5 minutes → Cool down to 25°C at a rate of 20°C / min → Hold at 25°C for 5 minutes → Heat up again at a rate of 20°C / min (2nd scan) The top of the endothermic peak in the second scan was taken as the melting point (Tm).

[0043] (2) Relative viscosity of semi-aromatic polyamide (A) The shavings obtained in (1) above were dissolved in 96% by mass sulfuric acid, and the measurement was carried out at a concentration of 1 g / dL and at 25°C.

[0044] (3) Flexural strength and flexural modulus After thoroughly drying the obtained pellets of the polyamide resin composition, dumbbell pieces were produced using an injection molding machine (α-100iA) manufactured by FANUC Corporation under the conditions of a cylinder temperature of (Tm+15°C) and a mold temperature of (Tm-190°C), where Tm is the melting point of the semi-aromatic polyamide (A) used. The resulting dumbbell specimens were used to measure the bending strength and bending modulus in accordance with ISO178.

[0045] (4) Linear expansion coefficient A rectangular columnar test piece (length 10 mm x width 5 mm x thickness 4 mm) was cut out from the center of the dumbbell specimen obtained in (3) above, so that the length direction of the test piece was the resin flow direction (MD), and another rectangular columnar test piece (length 10 mm x width 5 mm x thickness 4 mm) was cut out so that the length direction of the test piece was the direction (TD) perpendicular to the resin flow direction (MD). Measurement was carried out under the following conditions in a nitrogen atmosphere using a thermomechanical analyzer ("TMA Q400" manufactured by TA Instruments). Heat from -50°C to 200°C at a rate of 5°C / min (1st scan) → Hold at 200°C for 5 minutes → Cool to -50°C at a rate of 5°C / min → Hold at -50°C for 5 minutes → Heat again to 200°C at a rate of 5°C / min (2nd scan) The linear expansion coefficient at 80°C was determined in the second scan.

[0046] (5) Burr length The thoroughly dried pellets of the resin composition were used in an injection molding machine (α-100iA) manufactured by FANUC Corporation to prepare disc-shaped test pieces with a diameter of 60 mm and a thickness of 3 mm under the conditions of a cylinder temperature of (Tm+15°C) and a mold temperature of (Tm-190°C), where Tm is the melting point of the semi-aromatic polyamide used. The mold used had a gas vent with a thickness of 50 μm at the end of the flow. The length of the burr generated in the obtained disc-shaped test piece at the position corresponding to the gas vent portion of the mold was measured using a microscope.

[0047] (6) Water vapor permeability The thoroughly dried pellets of the resin composition were used in an injection molding machine (α-100iA) manufactured by FANUC Corporation to produce plate-shaped test pieces measuring 60 mm in length, 60 mm in width, and 1 mm in thickness under the conditions of a cylinder temperature of (Tm+15°C) and a mold temperature of (Tm-190°C), where Tm is the melting point of the semi-aromatic polyamide used. The obtained plate-shaped test piece was attached to the opening of a cup-shaped test jig containing pure water as the test liquid, so that it would form a 40 mm diameter lid, as shown in Figure 1. The test piece was then left to stand for 1000 hours in an atmosphere of 65°C with nitrogen flow, and the mass was measured before and after the test to determine the water vapor transmission rate.

[0048] B. Raw materials The raw materials used in the examples and comparative examples are shown below.

[0049] (1) Dicarboxylic acid component TPA: Terephthalic acid (2) Diamine component DDA: 1,10-decanediamine NDA: 1,9-nonanediamine MODA: 2-methyl-1,8-octanediamine (3) Monocarboxylic acid component STA: Stearic acid (4) Polymerization catalyst SHP: Sodium hypophosphite monohydrate

[0050] (5) Semi-aromatic polyamide Polyamide 10T [Step (i)] 4560 parts by weight of TPA powder as a dicarboxylic acid component, 9 parts by weight of SHP as a polymerization catalyst, and 490 parts by weight of STA as an end-capping agent were placed in a ribbon blender-type reactor and heated to 170 °C while stirring at 30 rpm using a double helical stirring blade under nitrogen sealing. Then, while maintaining the temperature at 170 °C and the rotation speed at 30 rpm, 4950 parts by weight of DDA heated to 100 °C was added to the TPA powder continuously (continuous injection method) at a rate of 33 parts by weight / min over 2.5 hours using a liquid injection device to obtain the reaction product. The molar ratio of the raw material monomers was DDA:TPA:STA = 49.6:47.4:3.0 (the equivalent ratio of the end groups of the raw material monomers was DDA:TPA:STA = 50.4:48.1:1.5). [Step (ii)] The reaction product obtained in step (i) was subsequently heated to 230°C under a nitrogen stream in the ribbon blender-type reaction apparatus used in step (i), and polymerized by heating at 230°C for 5 hours to obtain polyamide 10T. The resulting polyamide 10T had a melting point of 317°C and a relative viscosity of 2.25.

[0051] Polyamide 9T Polyamide 9T was obtained by carrying out the same procedure as in the production of polyamide 10T, except that the diamine components were changed to NDA / MODA=85 / 15 (molar ratio). The resulting polyamide 9T had a melting point of 300°C and a relative viscosity of 2.31.

[0052] (6) Filler (B) Glass flake A: REFG-315 manufactured by Nippon Sheet Glass Co., Ltd., average particle size 0.5 mm, average thickness 5 μm Glass flake B: Nippon Sheet Glass MEG160FY-M06, average particle size 0.16 mm, average thickness 0.7 μm Mica (muscovite): Kuraray 300-D Glass fiber: Nippon Electric Glass T-262H, aminosilane treated, fiber diameter 11 μm x fiber length 3 mm Carbon fiber: Mitsubishi Chemical Corporation TR06NLB5K, fiber diameter 7μm x fiber length 6mm Wollastonite: Kinseimatec SH-1250S, aminosilane treated, fiber diameter 8 μm, aspect ratio 15 Calcium carbonate: P-70 manufactured by Toyo Fine Chemical Co., Ltd.

[0053] (7) Polyphenylene ether (C) SABIC PPE PPO640

[0054] (8) Amorphous polyamide Grivory G21 manufactured by MSChemie Japan

[0055] Example 1 100 parts by mass of semi-aromatic polyamide (Polyamide 10T) was fed into the main feed port of a co-rotating twin-screw extruder (TEM37BS manufactured by Toshiba Machine Co., Ltd.) with a screw diameter of 37 mm and an L / D ratio of 40. 100 parts by mass of a plate-shaped filler (glass flake A) was fed from a side feeder and melt-kneaded. The cylinder temperature was (melting point of Polyamide 10T + 10°C), the screw rotation speed was 250 rpm, and the output rate was 35 kg / h. The strand was then drawn off and passed through a water bath to cool and solidify. The strand was then cut into pellets using a pelletizer to obtain polyamide resin composition pellets.

[0056] Examples 2 to 17, 30 to 41 (Examples 6, 7, 31 to 33 are reference examples.) , Comparative Examples 1 to 8 Polyamide resin composition pellets were obtained in the same manner as in Example 1, except that the formulation of the resin composition was changed as shown in Tables 1 and 2. In Comparative Example 7, pellets could not be obtained because the content of the filler was too high.

[0057] Example 18 A mixture was obtained by dry blending 100 parts by mass of semi-aromatic polyamide (polyamide 10T) and 25 parts by mass of polyphenylene ether. The mixture was fed into the main feed port of a 37mm screw diameter, 40L / D twin-screw extruder (Toshiba Machine Co., Ltd., TEM37BS), and 125 parts by mass of a plate-like filler (glass flake A) was fed from a side feeder, followed by melt-kneading. The cylinder temperature was (Polyamide 10T melting point + 10°C), the screw rotation speed was 250 rpm, and the output was 35 kg / h. The mixture was then taken up in the form of a strand, passed through a water bath to cool and solidify, and cut with a pelletizer to obtain polyamide resin composition pellets.

[0058] Examples 19 to 29, Comparative Example 9 Polyamide resin composition pellets were obtained in the same manner as in Example 18, except that the resin composition was changed as shown in Table 1.

[0059] The resin compositions and characteristic values ​​of the polyamide resin compositions obtained in the examples and comparative examples are shown in Tables 1 and 2.

[0060] [Table 1]

[0061] [Table 2]

[0062] The polyamide resin compositions of Examples 1 to 41 had excellent mechanical properties, with a flexural strength of 100 MPa or more and a flexural modulus of 10 GPa or more. The obtained molded articles also had a linear expansion coefficient of 70×10 at 80°C in both the flow direction (MD) and the transverse direction (TD). -6 (1 / ℃) or less, showing excellent dimensional stability. Furthermore, the burr length was 150 μm or less, showing excellent formability. Furthermore, the water vapor permeation amount was 150 mg or less, showing excellent low moisture permeability. By comparing the polyamide resin compositions of Examples 6 to 9 with the polyamide resin composition of Comparative Example 4, and the polyamide resin compositions of Examples 10 to 13 with the polyamide resin composition of Comparative Example 5, it can be seen that even if the filler content is the same, when a plate-like filler and a fibrous filler are used in combination, the dimensional stability of the resulting molded body is improved in both the flow direction (MD) and the transverse direction (TD). Comparing Examples 1, 2, 4, 5, 11, 13 to 17 with Examples 18 to 27, it can be seen that when part of the polyamide 10T is replaced with polyphenylene ether, the bending strength increases, the mechanical properties improve, the linear expansion coefficient decreases, and the dimensional stability improves.

[0063] The polyamide resin compositions of Comparative Examples 1 to 3 and 6 had a low filler content, and therefore had low bending strength, and the molded articles had a high linear expansion coefficient and long burrs. In the polyamide resin compositions of Comparative Examples 4 and 5, only a fibrous filler was used, and therefore the molded articles had a high TD linear expansion coefficient and long burr lengths. In the polyamide resin compositions of Comparative Examples 8 and 9, the mass ratio of the plate-like filler to the fibrous filler was not within a preferred range, and therefore the molded articles had a high TD linear expansion coefficient. [Explanation of symbols]

[0064] 1 test piece 2 Gasket 3 Test fixture 4 Test Solution

Claims

1. A resin composition containing a semi-aromatic polyamide (A) and a filler (B), The filler (B) contains a plate-like filler and a fibrous filler, the plate-like filler is at least one selected from glass flakes and mica, the fibrous filler is at least one selected from glass fiber, carbon fiber, and wollastonite; the total content of the plate-like filler and the fibrous filler is 100 to 250 parts by mass per 100 parts by mass of the semi-aromatic polyamide (A), the mass ratio of the plate-like filler to the fibrous filler (plate-like filler / fibrous filler) is 67 / 33 to 90 / 10; The linear expansion coefficient of the injection-molded body at 80°C in the direction perpendicular to the flow direction of the resin during injection molding is 60 x 10 －６ (1 / °C) or less.

2. A resin composition containing a semi-aromatic polyamide (A) and a filler (B), The filler (B) contains only a plate-like filler, the plate-like filler is at least one selected from glass flakes and mica, the content of the plate-like filler is 100 to 250 parts by mass per 100 parts by mass of the semi-aromatic polyamide (A), The linear expansion coefficient of the injection-molded body at 80°C in the direction perpendicular to the flow direction of the resin during injection molding is 60 x 10 －６ (1 / °C) or less.

3. 3. The polyamide resin composition according to claim 1, wherein the semi-aromatic polyamide (A) is composed of an aromatic dicarboxylic acid component and an aliphatic diamine component, and the aliphatic diamine component includes an aliphatic diamine having 8 or more carbon atoms.

4. The polyamide resin composition according to any one of claims 1 to 3, wherein the water vapor permeation amount determined by the following measurement method is 150 mg or less. Water vapor transmission measurement method: The polyamide resin composition (melting point: Tm) is thoroughly dried, and a test piece measuring 60 mm in length, 60 mm in width, and 1 mm in thickness is prepared under the conditions of a cylinder temperature of Tm+15°C and a mold temperature of Tm-190°C. The obtained test piece is attached to a cup-shaped test jig having a diameter of 40 mm and containing pure water so as to serve as a lid, and left to stand for 1000 hours in a nitrogen-infused, 65°C atmosphere. The difference in mass of the test jig before and after the test is taken as the water vapor permeation amount.

5. The polyamide resin composition according to any one of claims 1 to 4, characterized in that the length of burrs generated in an injection-molded article at a position corresponding to a gas vent portion of a mold during injection molding is 150 μm or less.

6. The polyamide resin composition according to any one of claims 1 to 5, further comprising 20 to 110 parts by mass of a polyphenylene ether (C).

7. A polyamide resin composition described in any one of claims 1 to 6, having a bending strength of 100 MPa or more as determined by the following measurement method. Bending strength measurement method: After the polyamide resin composition is thoroughly dried, dumbbell pieces are prepared under the conditions of a cylinder temperature of (Tm'+15°C) and a mold temperature of (Tm'-190°C), where Tm' is the melting point of the semi-aromatic polyamide (A) used, and the flexural strength of the obtained dumbbell pieces is measured in accordance with ISO 178.

8. A polyamide resin composition described in any one of claims 1 to 7, having a flexural modulus of elasticity of 10 GPa or more as determined by the following measurement method. Flexural modulus measurement method: After the polyamide resin composition is thoroughly dried, dumbbell pieces are prepared under the conditions of a cylinder temperature of (Tm'+15°C) and a mold temperature of (Tm'-190°C), where Tm' is the melting point of the semi-aromatic polyamide (A) used, and the flexural modulus of elasticity is measured using the obtained dumbbell pieces in accordance with ISO 178.

9. A molded article obtained by molding the polyamide resin composition according to any one of claims 1 to 8.

10. A vehicle-mounted camera part comprising the molded article according to claim 9.

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