Polyamide resin composition and molded articles made therefrom, automotive camera parts

Abstract

The present invention provides a polyamide resin composition that allows for the production of molded articles with excellent mechanical properties while also exhibiting excellent dimensional stability in both the flow direction (MD) and the orthogonal direction (TD). [Solution] A resin composition containing 100 parts by mass of semi-aromatic polyamide (A) and 70 to 250 parts by mass of filler (B), wherein the coefficient of linear expansion of the injection-molded article at 80°C in a direction perpendicular to the flow direction of the resin during injection molding is 70 × 10 -6 A polyamide resin composition characterized by having a temperature of (1 / °C) or less.

Description

Technical Field

[0001] The present invention relates to a polyamide resin composition, a molded article made therefrom, and a component for an in-vehicle camera.

Background Art

[0002] In recent years, vehicles are increasingly equipped with in-vehicle cameras to enhance driving safety. Among the components of an in-vehicle camera, resin materials are mainly used for the camera housing and the camera lens barrel. The camera housing is a case component that houses the structural components of the camera device. The camera lens barrel is located inside the camera housing and is a holder component that holds the camera lens. Both components are required to have excellent mechanical properties for protecting and holding the camera and the lens. Also, both components are required to have excellent dimensional stability so that the assembled lens does not distort even when exposed to high temperatures.

[0003] Patent Document 1 discloses that by incorporating a plate-like filler in a polyamide resin at 0.002 to 0.5% by mass based on the total polyamide resin composition, the obtained molded article has a small linear expansion coefficient in the resin flow direction (MD) during molding.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the polyamide resin composition described in Patent Document 1 uses polyamide 66, the obtained molded article has insufficient improvement in dimensional stability, and particularly has a problem that the linear expansion coefficient in the direction (TD) orthogonal to the resin flow direction (MD) during molding is large. In molded articles used for automotive camera components and the like, it is required that the coefficient of thermal expansion is small not only in the direction of resin flow (MD) during molding, but also in the direction perpendicular to it (TD).

[0006] The present invention aims to provide a polyamide resin composition that allows for the production of molded articles with excellent mechanical properties while also exhibiting excellent dimensional stability in both the flow direction (MD) and the orthogonal direction (TD). [Means for solving the problem]

[0007] The inventors of the present invention conducted extensive research to solve the aforementioned problems and, as a result, discovered that the above objective can be achieved by blending a specific amount of filler into a semi-aromatic polyamide, thus arriving at the present invention.

[0008] The polyamide resin composition of the present invention, which contains 100 parts by mass of semi-aromatic polyamide (A) and 70 to 250 parts by mass of filler (B), The coefficient of linear thermal expansion of the injection-molded product at 80°C in a direction perpendicular to the resin flow direction during injection molding is 70 × 10⁻⁶. -6 It is characterized by being (1 / ℃) or less. According to the polyamide resin composition of the present invention, it is preferable that the length of the burr generated in the injection-molded article at a position corresponding to the gas vent portion of the mold during injection molding is 150 μm or less. In the polyamide resin composition of the present invention, it is preferable that the filler (B) consists of a plate-shaped filler and a fibrous filler. According to the polyamide resin composition of the present invention, it is preferable that the mass ratio of plate-shaped filler to fibrous filler (plate-shaped filler / fibrous filler) is 50 / 50 to 90 / 10. According to the polyamide resin composition of the present invention, it is preferable that the plate-like filler is glass flakes and the fibrous filler is glass fibers. According to the polyamide resin composition of the present invention, it is preferable 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 polyphenylene ether (C). The molded article of the present invention is obtained by molding the above-mentioned polyamide resin composition. The component for an in-vehicle camera of the present invention is made of the above-described molded body. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a polyamide resin composition that can produce molded articles with excellent mechanical properties while also exhibiting excellent dimensional stability in both the flow direction (MD) and the orthogonal direction (TD). [Brief explanation of the drawing]

[0010] [Figure 1] This is a diagram illustrating a method for evaluating water vapor transmission. [Modes for carrying out 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 its main component. In this invention, "containing terephthalic acid as its main component" means that the aromatic dicarboxylic acid component contains 90 mol% or more of terephthalic acid. The terephthalic acid content in the aromatic dicarboxylic acid component is preferably 95 mol% or more, and more preferably 100 mol%. If the aromatic dicarboxylic acid component does not contain terephthalic acid as its main component, the resulting molded article may have poor dimensional stability.

[0014] The aromatic dicarboxylic acid component may contain other aromatic dicarboxylic acids other than terephthalic acid. Examples of other aromatic dicarboxylic acids include isophthalic acid and 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 an aliphatic diamine having 8 or more carbon atoms. The content of the aliphatic diamine 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 semi-aromatic polyamide (A) may have reduced processability. Examples of the aliphatic diamine 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 them, 1,10-decanediamine is more preferable because the semi-aromatic polyamide (A) has an excellent balance between heat resistance and processability, and water absorption and moisture permeability are suppressed.

[0016] The aliphatic diamine component may contain other aliphatic diamines other than the aliphatic diamine having 8 or more carbon atoms. Examples of other aliphatic diamines 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, as long as 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, undecanediic acid, and dodecanediic 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] Semi-aromatic polyamide (A) may contain monocarboxylic acid components in addition to dicarboxylic acid and diamine components. Examples of monocarboxylic acid components 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, molar carboxylic acids with a molecular weight of 140 or more are preferred because they improve the moldability of semi-aromatic polyamide (A), and stearic acid is more preferred because of its high versatility. The molecular weight of the monocarboxylic acid is 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 the monomers constituting the semi-aromatic polyamide. When the content of the monocarboxylic acid component is 0.3 to 5.0 mol%, the semi-aromatic polyamide (A) has improved molding processability without significantly reducing the molecular weight.

[0019] The semi-aromatic polyamide (A) can be produced by using conventionally known methods such as the thermal polymerization method or the solution polymerization method. Among them, the thermal polymerization method is preferably used because it is industrially advantageous. Examples of the thermal polymerization method 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] As step (i), for example, there is a method in which dicarboxylic acid powder is heated to a temperature not lower than the melting point of the diamine and not higher than the melting point of the dicarboxylic acid in advance, and the diamine is added to the dicarboxylic acid powder at this temperature so as to keep the dicarboxylic acid powder in a powdery state and substantially free of water. Alternatively, as another method, a suspension composed of molten diamine and solid dicarboxylic acid is stirred and mixed to obtain a mixture, and then, at a temperature lower than the melting point of the finally produced semi-aromatic polyamide, a salt formation reaction by the reaction of the dicarboxylic acid and the diamine and a low polymer formation reaction by the polymerization of the produced salt are carried out to obtain a mixture of the salt and the low polymer. In this case, crushing may be carried out while the reaction is in progress, or the reaction product may be taken out once after the reaction and then crushed. As step (i), the former method, which is easier to control the shape of the reaction product, is preferred.

[0021] As step (ii), for example, there is a method in which the reaction product obtained in step (i) is solid-phase polymerized at a temperature lower than the melting point of the finally produced semi-aromatic polyamide to increase the molecular weight to a predetermined value and obtain a semi-aromatic polyamide. The solid-phase polymerization is preferably carried out in an inert gas stream such as nitrogen at a polymerization temperature of 180 to 270°C and a reaction time of 0.5 to 10 hours.

[0022] 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 carried out in the same apparatus or in different apparatuses.

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

[0024] In the production of semi-aromatic polyamide (A), a polymerization catalyst may be used to increase the polymerization efficiency. Examples of polymerization catalysts include phosphoric acid, phosphorous acid, hypophosphorous acid, or salts thereof. The amount of polymerization catalyst added is usually preferably 2 mol% or less relative to 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 an organic compound or an inorganic compound. Examples of the form of the filler (B) include plate-like, fibrous, granular, and amorphous forms, among which plate-like, fibrous, and granular forms are preferred because they yield molded articles with excellent dimensional stability. The filler (B) may be used alone or in combination of multiple 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 resulting molded article has a reduced coefficient of linear expansion because the shrinkage of the semi-aromatic polyamide due to temperature changes is suppressed, and burrs that occur at the position corresponding to the gas vent of the mold can be suppressed. If the content of filler (B) is less than 70 parts by mass, the resulting molded article has a large coefficient of linear expansion. On the other hand, if the content of filler (B) exceeds 250 parts by mass, melt mixing with the aromatic polyamide resin becomes difficult, and it may not be possible to produce pellets of the resin composition.

[0027] Examples of plate-shaped fillers include glass flakes, talc, mica, and flaky graphite. Examples of mica include muscovite, fluorphlogopite, and tetrasilicate. Among these, glass flakes and mica are preferred due to their high 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 (stainless steel fibers, aluminum oxide fibers, etc.), ceramic fibers, boron whiskers, zinc oxide whiskers, asbestos, wollastonite, potassium titanate whiskers, calcium carbonate whiskers, aluminum borate whiskers, magnesium sulfate whiskers, needle-shaped titanium oxide, sepiolite, xonotlite, milled fibers, and cut fibers. Among these, glass fibers and wollastonite are preferred due to their high versatility. The surface of the fibrous filler is preferably surface-treated with an aminosilane coupling agent or epoxy resin to improve dispersibility in the semi-aromatic polyamide (A), and more preferably with an aminosilane coupling agent 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. Among these, calcium carbonate is preferred due to its high versatility.

[0030] In the present invention, the filler (B) preferably consists of a plate-shaped filler and a fibrous filler. The mass ratio of the plate-shaped filler to the fibrous filler (plate-shaped filler / fibrous unfiller) is preferably 50 / 50 to 90 / 10, and more preferably 55 / 45 to 85 / 15. By having a mass ratio of 50 / 50 to 90 / 10, the resulting molded article can have an even smaller coefficient of thermal expansion, thereby improving its mechanical properties. When the filler (B) is composed of a plate-shaped filler and a fibrous filler, it is preferable to use glass flakes as the plate-shaped filler and glass fibers or carbon fibers as the fibrous filler in terms of improving dimensional stability in both the flow direction (MD) and the orthogonal direction (TD). Furthermore, when part or all of the filler (B) is composed of carbon fibers, the carbon fiber content is preferably less than 100 parts by mass per 100 parts by mass of semi-aromatic polyamide (A). If the polyamide resin composition contains 100 parts by mass or more of carbon fibers, pellets may not be obtained.

[0031] (Polyphenylene ether (C)) The polyamide resin composition of the present invention preferably further contains polyphenylene ether (C). By containing polyphenylene ether (C) in the resin composition, the resulting molded article can have its burr length further shortened at the position corresponding to the gas vent of the mold during injection molding, and the amount of water vapor permeation can also be reduced. When the polyamide resin composition of the present invention contains polyphenylene ether (C), its content is preferably 20 to 110 parts by mass, and more preferably 25 to 100 parts by mass, per 100 parts by mass of semi-aromatic polyamide (A). Examples of commercially available polyphenylene ether (C) include Noryl PPO640 (manufactured by SABIC Corporation) and Yupiace PX-100F (manufactured by Mitsubishi Engineering Plastics Corporation).

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

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

[0034] Furthermore, injection-molded articles obtained from the polyamide resin composition of the present invention exhibit excellent dimensional stability in both the direction of resin flow during injection molding (MD) and the direction perpendicular to it (TD). Therefore, the coefficient of linear expansion at 80°C in either the MD or TD direction is 70 × 10⁻⁶. -6 It can be (1 / ℃) or less, preferably 60 × 10 -6 It can be (1 / ℃) or less, more preferably 45 × 10 -6 It can be (1 / °C) or less. 70 × 10 at 80°C in either the flow direction (MD) or the perpendicular direction (TD). -6A coefficient of linear expansion of 1 / °C or less can be achieved by including plate-like fillers such as glass flakes or mica in the resin composition constituting the molded product, including granular fillers, or including plate-like fillers and fibrous fillers 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 of 180 μm or less at the position corresponding to the gas vent portion of the mold during injection molding, preferably 150 μm or less, and more preferably 135 μm or less. Generally, since the generation of burrs during molding reduces production efficiency, a shorter burr length is preferable.

[0036] Furthermore, the polyamide resin composition of the present invention also exhibits excellent low water absorption and low moisture permeability. Water absorption and moisture permeability greatly affect dimensional stability, and generally, the lower the water absorption and moisture permeability, the better the dimensional stability. Also, when used as a component material for in-vehicle cameras, the lower the water absorption and moisture permeability, the more effectively lens fogging can be suppressed. In the present invention, the amount of water vapor permeated by a plate-shaped molded body formed from the resin composition to a thickness of 1 mm under a 65°C atmosphere can be set 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 preferable to produce it by a melt-kneading method. Examples of melt-kneading methods include using a batch-type kneader such as a Brabender, a Banbury mixer, a Henschel mixer, a helical rotor, rolls, 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 and does not decompose, and is usually preferably (Tm-20℃) to (Tm+50℃), where Tm is the melting point of the semi-aromatic polyamide (A).

[0038] Methods for processing the polyamide resin composition of the present invention include, for example, extruding the molten mixture into strands to form pellets; hot cutting or underwater cutting the molten mixture to form pellets; extruding and cutting into sheets; and extruding into blocks and crushing to form 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 sintering molding. Injection molding is preferred because it offers significant improvements in mechanical properties and moldability. The injection molding machine is not particularly limited, but examples include a screw-in-line injection molding machine or a plunger-type injection molding machine. The polyamide resin composition, heated and melted in the cylinder of the injection molding machine, is measured for each shot, injected into the mold in a molten state, cooled and solidified in a predetermined shape, and then removed from the mold as a molded body. The resin temperature during injection molding is preferably above Tm, where Tm is the melting point of the semi-aromatic polyamide (A), and more preferably below (Tm + 50°C). It is preferable that the polyamide resin composition pellets used when heating and melting the polyamide resin composition are sufficiently dry. If the polyamide resin composition pellets contain a large amount of moisture, the resin may foam in the cylinder of the injection molding machine, making it difficult to obtain an optimal molded body. 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, per 100 parts by mass of the polyamide resin composition.

[0040] Molded articles obtained from the polyamide resin composition of the present invention exhibit excellent mechanical properties while also having excellent dimensional stability in both the flow direction (MD) and the orthogonal direction (TD). Therefore, they can be suitably used for automotive camera components, and are particularly suitable for lens barrels and housings. In addition, they can be used for electrical and electronic connectors, switches, aluminum electrolytic capacitor terminal blocks, actuator components, LED reflectors, sensors, sockets, jacks, fuse holders, relays, coil bobbins, resistors, ICs, LED housings, and the like. [Examples]

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

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

[0044] (3) Bending strength, bending modulus After thoroughly drying the obtained polyamide resin composition pellets, dumbbell pieces were fabricated using a FANUC injection molding machine (α-100iA) under the conditions of cylinder temperature (Tm + 15°C) and mold temperature (Tm - 190°C), with Tm being the melting point of the semi-aromatic polyamide (A) used. The obtained dumbbell pieces were used to measure their bending strength and bending modulus in accordance with ISO 178.

[0045] (4) Coefficient of linear expansion From the center of the dumbbell piece obtained in (3) above, a prismatic test piece (10 mm long × 5 mm wide × 4 mm thick) was cut out so that the length of the test piece was in the direction of resin flow (MD), and a prismatic test piece (10 mm long × 5 mm wide × 4 mm thick) was cut out so that the length of the test piece was in the direction perpendicular to the direction of resin flow (TD). The measurements were taken using a thermomechanical analyzer (TA Instruments "TMA Q400") under a nitrogen atmosphere and the following conditions. Heat from -50°C to 200°C at a heating rate of 5°C / min (1st scan) → Hold at 200°C for 5 minutes → Cool down to -50°C at a heating rate of 5°C / min → Hold at -50°C for 5 minutes → Heat again to 200°C at a heating rate of 5°C / min (2nd scan) The coefficient of linear thermal expansion at 80°C was determined for the second scan.

[0046] (5) Burr length A fully dried resin composition pellet was used to produce disc-shaped test specimens with a diameter of 60 mm and a thickness of 3 mm using a FANUC injection molding machine (α-100iA). The melting point of the semi-aromatic polyamide used was denoted as Tm, and the cylinder temperature was set to Tm + 15°C and the mold temperature to Tm - 190°C. The mold used had a gas vent with a thickness of 50 μm at the flow end. The length of the burrs that formed on the obtained disc-shaped test specimen at the location corresponding to the gas vent of the mold was measured using a microscope.

[0047] (6) Water vapor transmission A plate-shaped test specimen measuring 60 mm in length, 60 mm in width, and 1 mm in thickness was prepared from a fully dried resin composition pellet using a FANUC injection molding machine (α-100iA) under the conditions of cylinder temperature (Tm + 15°C) and mold temperature (Tm - 190°C), with the melting point of the semi-aromatic polyamide used being Tm. Using the obtained plate-shaped test specimens, as shown in Figure 1, the specimens were mounted on the opening of a cup-shaped test fixture containing pure water as the test liquid, with the specimens forming the lid portion with a diameter of 40 mm. After standing for 1000 hours under a nitrogen inflow and 65°C atmosphere, the mass was measured before and after the test, and the amount of water vapor permeation was determined.

[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 components • DDA: 1,10-decanediamine • NDA: 1,9-nonanediamine • MODA: 2-methyl-1,8-octanediamine (3) Monocarboxylic acid components • STA: Stearic acid (4) Polymerization catalyst • SHP: Sodium hypophosphate monohydrate

[0050] (5) Semi-aromatic polyamides • Polyamide 10T [Process (i)] 4560 parts by mass of TPA powder as the dicarbon component, 9 parts by mass of SHP as the polymerization catalyst, and 490 parts by mass of STA as the end-sealing agent were placed in a ribbon blender type reactor and heated to 170°C under nitrogen sealing while stirring at a rotation speed of 30 rpm using a double helical type stirring blade. Then, while maintaining the temperature at 170°C and the rotation speed at 30 rpm, 4950 parts by mass of DDA, which had been heated to 100°C, was continuously added to the TPA powder at a rate of 33 parts by mass / 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 polymerized in the ribbon blender reactor used in step (i) under a nitrogen atmosphere by raising the temperature to 230°C and heating at 230°C for 5 hours to obtain polyamide 10T. The obtained polyamide 10T had a melting point of 317°C and a relative viscosity of 2.25.

[0051] • Polyamide 9T Polyamide 9T was obtained by performing the same procedure as when polyamide 10T was produced, except that the diamine component was changed to an NDA / MODA ratio of 85 / 15 (molar ratio). The obtained 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: MEG160FY-M06 manufactured by Nippon Sheet Glass Co., Ltd., average particle size 0.16 mm, average thickness 0.7 μm • Mica (white mica): Kuraray 300-D • Glass fiber: T-262H manufactured by Nippon Electric Glass Co., Ltd., 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: SH-1250S manufactured by Kinsei Matec, aminosilane treated, fiber diameter 8μm, 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 polyamides • Grivory G21 manufactured by M-Scheme Japan Co., Ltd.

[0055] Example 1 100 parts by mass of semi-aromatic polyamide (polyamide 10T) was supplied to the main feed port of a co-direction twin-screw extruder (Toshiba Machine Co., Ltd. TEM37BS) with a screw diameter of 37 mm and an L / D ratio of 40. 100 parts by mass of plate-shaped filler (glass flake A) was supplied from a side feeder, and melt-mixing was performed. The cylinder temperature was (melting point of polyamide 10T + 10°C), the screw rotation speed was 250 rpm, and the discharge rate was 35 kg / hour. Afterwards, the mixture was taken up in strand form, cooled and solidified in a water bath, and then cut with a pelletizer to obtain polyamide resin composition pellets.

[0056] Examples 2-17, 30-41, Comparative Examples 1-8 Polyamide resin composition pellets were obtained by performing the same procedure as in Example 1, except that the composition of the resin composition was changed as shown in Tables 1 and 2. In Comparative Example 7, pellets could not be obtained because the filler content 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 above mixture was supplied to the main feed port of a coaxial twin-screw extruder (TEM37BS, manufactured by Toshiba Machine Co., Ltd.) with a screw diameter of 37 mm and an L / D ratio of 40. 125 parts by mass of plate-shaped filler (glass flake A) were supplied from the side feeder, and melt-mixing was performed. The cylinder temperature was (melting point of polyamide 10T + 10°C), the screw rotation speed was 250 rpm, and the discharge rate was 35 kg / hour. After that, the mixture was taken up in strand form, cooled and solidified in a water bath, and then cut with a pelletizer to obtain polyamide resin composition pellets.

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

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

[0060] [Table 1]

[0061] [Table 2]

[0062] The polyamide resin compositions of Examples 1 to 41 had a flexural strength of 100 MPa or more, a flexural modulus of elasticity of 10 GPa or more, and excellent mechanical properties. Furthermore, the resulting molded articles had a coefficient of linear expansion at 80°C of 70 × 10⁻¹⁰ in both the flow direction (MD) and the orthogonal direction (TD). -6 The temperature was below (1 / °C), indicating excellent dimensional stability. Furthermore, the burr length was 150 μm or less, demonstrating excellent moldability. On top of that, the water vapor permeability was 150 mg or less, indicating excellent low moisture permeability. By comparing the polyamide resin compositions of Examples 6-9 with the polyamide resin composition of Comparative Example 4, and the polyamide resin compositions of Examples 10-13 with the polyamide resin composition of Comparative Example 5, it can be seen that even with the same filler content, using both plate-shaped and fibrous fillers improves the dimensional stability of the resulting molded articles in both the flow direction (MD) and the orthogonal direction (TD). By comparing Examples 1, 2, 4, 5, 11, 13-17 with Examples 18-27, it can be seen that replacing a portion of polyamide 10T with polyphenylene ether increases flexural strength, improves mechanical properties, lowers the coefficient of thermal expansion, and improves dimensional stability.

[0063] The polyamide resin compositions of Comparative Examples 1-3 and 6 had low filler content, resulting in low flexural strength, a high coefficient of thermal expansion in the molded articles, and long burr lengths. In Comparative Examples 4 and 5, the polyamide resin compositions used only fibrous fillers, resulting in molded articles with a high coefficient of thermal expansion (TD) and long burr lengths. In Comparative Examples 8 and 9, the polyamide resin compositions had a high coefficient of thermal expansion (TD) in the molded articles because the mass ratio of the plate-like filler to the fibrous filler was not within a favorable range. [Explanation of symbols]

[0064] 1 Test specimen 2. Packing 3. Test fixtures 4 Test solution

Claims

1. A resin composition containing 100 parts by mass of semi-aromatic polyamide (A) and 70 to 250 parts by mass of filler (B), The coefficient of linear thermal expansion of the injection-molded product at 80°C in a direction perpendicular to the resin flow direction during injection molding is 70 × 10⁻⁶. －６ A polyamide resin composition characterized by having a temperature of (1 / °C) or less.

2. The polyamide resin composition according to claim 1, characterized in that the length of the burr generated in the injection-molded article at a position corresponding to the gas vent portion of the mold during injection molding is 150 μm or less.

3. The polyamide resin composition according to claim 1 or 2, characterized in that the filler (B) consists of a plate-shaped filler and a fibrous filler.

4. The polyamide resin composition according to claim 3, characterized in that the mass ratio of plate-shaped filler to fibrous filler (plate-shaped filler / fibrous filler) is 50 / 50 to 90 / 10.

5. The polyamide resin composition according to claim 3 or 4, characterized in that the plate-like filler is glass flakes and the fibrous filler is glass fiber.

6. The polyamide resin composition according to claim 3 or 4, characterized in that the plate-like filler is glass flakes and the fibrous filler is carbon fiber.

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

8. A molded article obtained by molding a polyamide resin composition according to any one of claims 1 to 7.

9. A component for an in-vehicle camera, comprising the molded body described in claim 8.

Images