Polyamide resin composition, molded article made therefrom, and component for in-vehicle camera

Abstract

The present invention provides a polyamide resin composition, which is characterized in that it is a resin composition containing 100 parts by mass of a semi-aromatic polyamide (A) and 70 to 250 parts by mass of a filler (B), and the linear expansion coefficient at 80 °C in the direction orthogonal to the resin flow direction during injection molding of the injection molded body is 70×10 －6 (1 / °C) or less.

Description

Technical Field

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

[0002] In recent years, in order to improve driving safety, most vehicles are provided with in-vehicle cameras. Among the structural components of in-vehicle cameras, resin materials are mainly used for the camera housing and the camera lens barrel. The camera housing is a housing component that houses the structural components of the camera device. In addition, the camera lens barrel is a support component that is present in the camera housing and holds the lens for the camera. Since each component protects and holds the camera and the lens, excellent mechanical properties are required. In addition, it is required that each component has excellent dimensional stability even when exposed to high temperatures, so that the assembled lens does not deform.

[0003] Patent Document 1 discloses that by containing 0.002 to 0.5% by mass of a plate-like filler relative to the entire polyamide resin composition in a polyamide resin, the linear expansion coefficient in the resin flow direction (MD) during molding of the obtained molded article becomes small.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-210544 Summary of the Invention

[0007] However, since the polyamide resin composition described in Patent Document 1 uses polyamide 66, the improvement in the dimensional stability of the obtained molded article is insufficient, and in particular, there is a problem that the linear expansion coefficient in the direction (TD) orthogonal to the resin flow direction (MD) during molding is large.

[0008] In a molded article for use in an in-vehicle camera component or the like, it is required not only that the resin flow direction (MD) during molding is small, but also that the linear expansion coefficient in the orthogonal direction (TD) is small.

[0009] An object of the present invention is to provide a polyamide resin composition capable of obtaining a molded article having excellent mechanical properties and excellent dimensional stability in either the flow direction (MD) or the orthogonal direction (TD).

[0010] The inventors of the present invention repeatedly conducted in-depth studies to solve the above problems, and as a result, found that by blending a specific amount of a filler in a semi-aromatic polyamide, the above object can be achieved, thereby realizing the present invention.

[0011] The polyamide resin composition of the present invention contains 100 parts by mass of semi-aromatic polyamide (A) and 70 to 250 parts by mass of filler (B), and is characterized in that the linear expansion coefficient at 80 °C in the direction orthogonal to the resin flow direction during injection molding of the injection molded body is 70×10 －6 (1 / °C) or less.

[0012] In the polyamide resin composition according to the present invention, it is preferable that the length of the weld line generated at the position corresponding to the gas discharge part of the mold during injection molding of the injection molded body is 150 μm or less.

[0013] In the polyamide resin composition according to the present invention, it is preferable that the filler (B) is composed of a plate-like filler and a fibrous filler.

[0014] In the polyamide resin composition according to the present invention, it is preferable that the mass ratio of the plate-like filler to the fibrous filler (plate-like filler / fibrous filler) is 50 / 50 to 90 / 10.

[0015] In the polyamide resin composition according to the present invention, it is preferable that the plate-like filler is a glass sheet and the fibrous filler is glass fiber.

[0016] In the polyamide resin composition according to the present invention, it is preferable that the plate-like filler is a glass sheet and the fibrous filler is carbon fiber.

[0017] In the polyamide resin composition according to the present invention, it is further preferable to contain 20 to 110 parts by mass of polyphenylene ether (C).

[0018] The molded body of the present invention is a molded body formed by molding the above polyamide resin composition.

[0019] The in-vehicle camera component of the present invention is a component composed of the above molded body.

[0020] According to the present invention, a polyamide resin composition capable of obtaining a molded body having excellent mechanical properties and excellent dimensional stability in any one of the flow direction (MD) and the orthogonal direction (TD) can be provided. Description of the Drawings

[0021] Figure 1 It is an explanatory diagram of a method for evaluating the water vapor transmission rate. Detailed Description

[0022] The polyamide resin composition of the present invention contains semi-aromatic polyamide (A) and filler (B).

[0023] (Semi-aromatic polyamide (A))

[0024] The semi-aromatic polyamide (A) used in the present invention is composed of an aromatic dicarboxylic acid component and an aliphatic diamine component.

[0025] The aromatic dicarboxylic acid component preferably contains terephthalic acid as the main component. In the present invention, "with terephthalic acid as the 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 the main component, the dimensional stability of the obtained molded body deteriorates.

[0026] 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.

[0027] The aliphatic diamine component preferably contains an aliphatic diamine having 8 or more carbon atoms as the main component. In the present invention, "with an aliphatic diamine having 8 or more carbon atoms as the 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, more preferably 100 mol%. If the aliphatic diamine component does not contain an aliphatic diamine having 8 or more carbon atoms as the main component, the processability of the semi-aromatic polyamide (A) sometimes decreases. 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, 1,12-dodecanediamine. Among them, 1,10-decanediamine is more preferred because the balance between heat resistance and processability of the semi-aromatic polyamide (A) is excellent and water absorption and moisture permeability are suppressed.

[0028] 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-ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 2-methyl-1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine.

[0029] The semi-aromatic polyamide (A) may contain dicarboxylic acids other than aromatic dicarboxylic acids, diamines other than aliphatic diamines, lactams, and ω-amino carboxylic acids, as long as the effects of the present invention are not impaired. Examples of the 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 the diamines other than aliphatic diamines include alicyclic diamines such as 1,4-cyclohexanediamine; and aromatic diamines such as m-xylylenediamine and p-xylylenediamine. Examples of the lactams include caprolactam and laurolactam. Examples of the ω-amino carboxylic acids include 6-aminohexanoic acid and 11-aminoundecanoic acid.

[0030] In addition to the dicarboxylic acid component and the diamine component, the semi-aromatic polyamide (A) may also contain a monocarboxylic acid component. Examples of the monocarboxylic acid component include aliphatic monocarboxylic acids such as stearic acid, caprylic acid, pelargonic acid, capric 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 them, due to the improvement of the molding processability of the semi-aromatic polyamide (A), monocarboxylic acids having a molecular weight of 140 or more are preferred, and due to high versatility, stearic acid is more preferred. It should be noted that the molecular weight of the monocarboxylic acid is the molecular weight of the monocarboxylic acid used as the raw material during polymerization.

[0031] The content of the monocarboxylic acid component is preferably 0.3 to 5.0 mol%, more preferably 0.6 to 4.0 mol%, and still more preferably 1.0 to 3.5 mol% based on all the monomers constituting the semi-aromatic polyamide. If 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 even if the molecular weight is not significantly reduced.

[0032] The semi-aromatic polyamide (A) can be produced by using conventionally known methods such as the thermal polymerization method and the solution polymerization method. Among them, due to industrial advantages, the thermal polymerization method is preferably used. Examples of the thermal polymerization method include a method including step (i) of obtaining a reaction product from a dicarboxylic acid component and a diamine component, and step (ii) of polymerizing the obtained reaction product.

[0033] As step (i), for example, a method can be cited in which a dicarboxylic acid powder is preheated to a temperature above the melting point of a diamine and below the melting point of the dicarboxylic acid, and the diamine is added to the dicarboxylic acid powder at this temperature in a manner that actually does not contain water in order to maintain the state of the dicarboxylic acid powder. Or, as another method, a suspension composed of a molten diamine and a solid dicarboxylic acid is stirred and mixed, and after obtaining a mixed solution, a reaction for forming a salt from the dicarboxylic acid and the diamine and a reaction for forming an oligomer by polymerization of the formed salt are carried out at a temperature lower than the melting point of the finally formed semi-aromatic polyamide to obtain a mixture of a salt and an oligomer. In this case, pulverization can be carried out while the reaction is in progress, or it can be temporarily taken out after the reaction and then pulverized. As step (i), the former method in which the shape of the reaction product is easily controlled is preferred.

[0034] As step (ii), for example, a method can be cited in which the reaction product obtained in step (i) is subjected to solid-phase polymerization at a temperature lower than the melting point of the finally formed semi-aromatic polyamide to increase its molecular weight to a specified molecular weight to obtain a semi-aromatic polyamide. The solid-phase polymerization is preferably carried out in a non-reactive gas stream such as nitrogen at a polymerization temperature of 180 to 270°C and a reaction time of 0.5 to 10 hours.

[0035] The reaction apparatuses for steps (i) and (ii) are not particularly limited, and known apparatuses can be used. Steps (i) and (ii) can be carried out using the same apparatus, or different apparatuses can be used.

[0036] The heating method in the heat polymerization method is not particularly limited. For example, a method of heating a reaction vessel using a medium such as water, steam, or heat transfer oil, a method of heating a reaction vessel using an electric heater, and a method of using frictional heat accompanying the movement of the contents such as stirring heat generated by stirring can be cited. In addition, these methods can be combined.

[0037] In the production of the semi-aromatic polyamide (A), a polymerization catalyst can be used to improve the polymerization efficiency. As the polymerization catalyst, for example, phosphoric acid, phosphorous acid, hypophosphorous acid, or their salts can be cited. The addition amount of the polymerization catalyst is usually preferably 2 mol% or less based on all the monomers constituting the semi-aromatic polyamide (A).

[0038] (Filler (B))

[0039] The filler (B) used in the present invention can be composed of an organic compound or an inorganic compound.

[0040] As the form of the filler (B), for example, a plate shape, a fibrous shape, a granular shape, and an amorphous shape can be mentioned. Among them, since a molded article excellent in dimensional stability can be obtained, a plate shape, a fibrous shape, and a granular shape are preferred. The filler (B) can be used alone or in combination of two or more.

[0041] In the resin composition of the present invention, the content of the filler (B) needs to be 70 to 250 parts by mass, preferably 80 to 200 parts by mass, and more preferably 90 to 150 parts by mass with respect to 100 parts by mass of the semi-aromatic polyamide (A). If the content of the filler (B) in the resin composition is 70 to 250 parts by mass, the shrinkage of the obtained molded article due to the temperature change of the semi-aromatic polyamide is suppressed, so that the linear expansion coefficient can be reduced, and further, the seam ridge generated at the position corresponding to the gas discharge part of the mold can be suppressed. If the content of the filler (B) is less than 70 parts by mass, the linear expansion coefficient of the obtained molded article becomes large. On the other hand, if the content of the filler (B) exceeds 250 parts by mass, it is difficult to melt-knead with the semi-aromatic polyamide resin, and sometimes it is impossible to produce the particles of the resin composition.

[0042] As the plate-shaped filler, for example, glass flakes, talc, mica, and flaky graphite can be mentioned. As mica, muscovite, fluorophlogopite, and tetrasilicic mica can be mentioned. Among them, glass flakes and mica are preferred due to their high versatility.

[0043] As the fibrous filler, for example, carbon fiber, glass fiber, silica fiber, silica-alumina fiber, zirconia fiber, alumina fiber, silicon carbide fiber, metal fiber (stainless steel fiber, alumina fiber, etc.), ceramic fiber, boron whisker, zinc oxide whisker, asbestos, wollastonite, potassium titanate whisker, calcium carbonate whisker, aluminum borate whisker, magnesium sulfate whisker, acicular titanium oxide, sepiolite, xonotlite, milled fiber, and chopped fiber can be mentioned. Among them, glass fiber and wollastonite are preferred due to their high versatility. In order to improve the dispersibility in the semi-aromatic polyamide (A), the surface of the fibrous filler is preferably surface-treated with an amino-silane coupling agent or an epoxy resin. Among them, in order to improve the mechanical properties and the adhesiveness to adhesives such as epoxy resin, surface treatment with an amino-silane coupling agent is more preferred.

[0044] As the granular filler, for example, alumina, titanium oxide, boron nitride, silicon carbide, and calcium carbonate can be mentioned. Among them, calcium carbonate is preferred due to its high versatility.

[0045] 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 filler) is preferably 50 / 50 to 90 / 10, more preferably 55 / 45 to 85 / 15. By setting the above mass ratio to 50 / 50 to 90 / 10, the resulting molded article can further reduce the linear expansion coefficient and improve the mechanical properties.

[0046] When the filler (B) consists of a plate-shaped filler and a fibrous filler, from the viewpoint of improving the dimensional stability in either the machine direction (MD) or the transverse direction (TD), it is preferable to use glass flakes as the plate-shaped filler and glass fibers or carbon fibers as the fibrous filler.

[0047] In addition, when a part or all of the filler (B) is composed of carbon fibers, the content of the carbon fibers is preferably less than 100 parts by mass relative to 100 parts by mass of the semi-aromatic polyamide (A). If the content of the carbon fibers is 100 parts by mass or more, it may sometimes be impossible to obtain pellets of the polyamide resin composition.

[0048] (Polyphenylene ether (C))

[0049] The polyamide resin composition of the present invention further preferably contains a polyphenylene ether (C). By containing the polyphenylene ether (C) in the resin composition, the resulting molded article can further shorten the length of the weld line generated at the position corresponding to the gas discharge part of the mold during injection molding, and can also reduce the water vapor transmission rate.

[0050] When the polyamide resin composition of the present invention contains a polyphenylene ether (C), its content is preferably 20 to 110 parts by mass, more preferably 25 to 100 parts by mass, relative to 100 parts by mass of the semi-aromatic polyamide (A).

[0051] Examples of commercially available products of the polyphenylene ether (C) include NORYL PPO640 (manufactured by SABIC) and Iupiace PX-100F (manufactured by Mitsubishi Engineering Plastics Corporation).

[0052] (Additives, other resins)

[0053] The polyamide resin composition of the present invention may contain other fillers other than the filler (B), ultraviolet absorbers, light stabilizers, heat stabilizers, antioxidants, mold release agents, lubricants, colorants, antistatic agents, nucleating agents, etc., as long as the effects of the present invention are not impaired, and other thermoplastic resins such as semi-aromatic polyamide (A) and amorphous polyamide other than polyphenylene ether (C). When additives are contained, the content is preferably 2% by mass or less of the polyamide resin composition. When the above other thermoplastic resins are contained, the content is preferably 50% by mass or less of the polyamide resin composition.

[0054] (Properties)

[0055] Since the polyamide resin composition of the present invention has excellent mechanical properties, the flexural strength of the obtained molded body can be set to 100 MPa or more, preferably 120 MPa or more, more preferably 140 MPa or more. In addition, the flexural modulus of elasticity can be set to 10 GPa or more, preferably 12 GPa or more.

[0056] In addition, since the injection molded body obtained from the polyamide resin composition of the present invention has excellent dimensional stability in any one of the resin flow direction (MD) and the orthogonal direction (TD) during injection molding, the linear expansion coefficient at 80 °C in any one of MD and TD can be set to 70×10 －6 (1 / °C) or less, preferably 60×10 －6 (1 / °C) or less, more preferably 45×10 －6 (1 / °C) or less. By including plate-like fillers such as glass flakes and mica, or granular fillers, or by including plate-like fillers and fibrous fillers in a specific mass ratio in the resin composition constituting the molded body, it is possible to achieve a linear expansion coefficient at 80 °C in any one of the flow direction (MD) and the orthogonal direction (TD) of 70×10 －6 (1 / °C) or less.

[0057] In addition, the length of the weld line generated at the position corresponding to the gas discharge part of the mold during injection molding of the injection molded body obtained from the polyamide resin composition of the present invention can be set to 180 μm or less, preferably 150 μm or less, more preferably 135 μm or less. Generally speaking, if a weld line is generated during molding, the production efficiency becomes low, so the shorter the length of the weld line, the more preferable.

[0058] In addition, the polyamide resin composition of the present invention is also excellent in low water absorption and low moisture permeability. Water absorption and moisture permeability have a great impact on dimensional stability. Generally speaking, the lower the water absorption and moisture permeability, the more excellent the dimensional stability. In addition, when used as a component material for in-vehicle cameras, the lower the water absorption and moisture permeability, the more effectively the fogging of the lens can be suppressed. In the present invention, the amount of water vapor permeation of the resin composition formed into a plate-shaped molded body with a thickness of 1 mm in an atmosphere of 65°C can be 150 mg or less, preferably 130 mg or less, and more preferably 120 mg or less.

[0059] (Manufacturing method)

[0060] In the present invention, the method for manufacturing the resin composition by blending the respective components constituting the resin composition is not particularly limited, and it is preferably manufactured by a melt-kneading method. Examples of the melt-kneading method include methods using batch-type kneaders such as Brabender, Banbury mixers, Henschel mixers, screw rotors, rolls, single-screw extruders, twin-screw extruders, etc. The melt-kneading temperature is selected from the region where the semi-aromatic polyamide (A) melts without decomposition. Generally, the melting point of the semi-aromatic polyamide (A) is set as Tm, and it is preferably (Tm - 20°C) to (Tm + 50°C).

[0061] As a processing method of the polyamide resin composition of the present invention, for example, there can be mentioned a method of extruding the molten mixture into a long strip to form a granular shape; a method of hot-cutting and underwater cutting the molten mixture to form a granular shape; a method of extruding it into a sheet and shearing; a method of extruding it into a block and pulverizing it to form a powder shape.

[0062] (Molded body)

[0063] As a method for molding the polyamide resin composition of the present invention, for example, an injection molding method, an extrusion molding method, a blow molding method, and a sintering molding method can be cited. Since the effect of improving mechanical properties and moldability is great, the injection molding method is preferably used. The injection molding machine is not particularly limited, and for example, a screw in-line injection molding machine or a plunger injection molding machine can be cited. The polyamide resin composition heated and melted in the barrel of the injection molding machine is metered according to the injection amount, injected into the mold in a molten state, cooled and solidified into a specified shape, and then taken out of the mold as a molded body. Let the melting point of the semi-aromatic polyamide (A) be Tm. The resin temperature during injection molding is preferably Tm or higher, and more preferably less than (Tm + 50°C). It should be noted that the polyamide resin composition particles used for heating and melting the polyamide resin composition are preferably sufficiently dried. If the water content in the polyamide resin composition particles is high, the resin foams in the barrel of the injection molding machine, and it is difficult to obtain an optimal molded body. With respect to 100 parts by mass of the polyamide resin composition, the water content rate of the polyamide resin composition particles used in injection molding is preferably less than 0.3 parts by mass, and more preferably less than 0.1 parts by mass.

[0064] The molded body obtained from the polyamide resin composition of the present invention has excellent mechanical properties and excellent dimensional stability in any one of the flow direction (MD) and the orthogonal direction (TD). Therefore, it can be suitably used for components for in-vehicle cameras, and can be suitably used by utilizing a lens barrel and a housing. In addition, it can also be used for electrical and electronic connectors, switches, aluminum electrolytic capacitor terminal boards, actuator components, LED reflectors, sensors, plugs, sockets, fuse holders, relays, coil bobbins, resistors, ICs, LED housings, etc.

[0065] Examples

[0066] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

[0067] A. Measurement method

[0068] (1) Melting point of semi-aromatic polyamide (A)

[0069] The particles of the semi-aromatic polyamide (A) that had been sufficiently dried were cut, and 10 mg of the chips were measured using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer under the following conditions in a nitrogen atmosphere.

[0070] Heated at a heating rate of 20°C / minute to 350°C (first scan) → held at 350°C for 5 minutes → cooled at a cooling rate of 20°C / minute to 25°C → held at 25°C for 5 minutes → heated again at a heating rate of 20°C / minute (second scan)

[0071] Set the peak of the endothermic peak in the second scan as the melting point (Tm).

[0072] (2) Relative viscosity of semi-aromatic polyamide (A)

[0073] The chips obtained in (1) above were dissolved in 96 mass% sulfuric acid and measured under the conditions of a concentration of 1 g / dL and 25 °C.

[0074] (3) Flexural strength, flexural modulus

[0075] After sufficiently drying the particles of the obtained polyamide resin composition, using an injection molding machine (α-100iA) manufactured by FANUC Corporation, with the melting point of the semi-aromatic polyamide (A) used set as Tm, dumbbell-shaped specimens were prepared under the conditions of a barrel temperature (Tm + 15 °C) and a mold temperature (Tm - 190 °C).

[0076] Using the obtained dumbbell-shaped specimens, the flexural strength and flexural modulus were measured based on ISO178.

[0077] (4) Coefficient of linear expansion

[0078] From the central part of the dumbbell-shaped specimens obtained in (3) above, prismatic specimens (length 10 mm × width 5 mm × thickness 4 mm) were cut out in such a way that the length direction of the test piece was the resin flow direction (MD), and in addition, prismatic specimens (length 10 mm × width 5 mm × thickness 4 mm) were cut out in such a way that the length direction of the test piece was the direction (TD) orthogonal to the resin flow direction (MD).

[0079] Using a thermomechanical analysis device ("TMA Q400" manufactured by TA INSTRUMENTS), the measurement was carried out under the following conditions in a nitrogen atmosphere.

[0080] At a heating rate of 5 °C / minute, heat from -50 °C to 200 °C (first scan) → hold at 200 °C for 5 minutes → cool to -50 °C at a cooling rate of 5 °C / minute → hold at -50 °C for 5 minutes → heat to 200 °C again at a heating rate of 5 °C / minute (second scan)

[0081] Determine the coefficient of linear expansion at 80 °C in the second scan.

[0082] (5) Weld line length

[0083] For the particles of the sufficiently dried resin composition, using an injection molding machine (α-100iA) manufactured by FANUC Corporation, setting the melting point of the semi-aromatic polyamide used as Tm, under the conditions of barrel temperature (Tm + 15 °C) and mold temperature (Tm - 190 °C), a disc-shaped test piece with a diameter of 60 mm and a thickness of 3 mm was made. A mold with an exhaust port having a thickness of 50 μm at the flow end was used.

[0084] The length of the seam ridge generated at the position corresponding to the gas discharge part of the mold on the disc-shaped test piece measured using a microscope.

[0085] (6) Water vapor transmission rate

[0086] For the particles of the sufficiently dried resin composition, using an injection molding machine (α-100iA) manufactured by FANUC Corporation, setting the melting point of the semi-aromatic polyamide used as Tm, under the conditions of barrel temperature (Tm + 15 °C) and mold temperature (Tm - 190 °C), a plate-shaped test piece with a length of 60 mm, a width of 60 mm, and a thickness of 1 mm was made.

[0087] Using the obtained plate-shaped test piece, as Figure 1 shown, the test piece was installed to be a lid part with a diameter of 40 mm at the opening of a cup-shaped test fixture filled with pure water as the test liquid, nitrogen was introduced, and after standing for 1000 hours in a 65 °C atmosphere, the mass before and after the test was measured to obtain the water vapor transmission rate.

[0088] B. Raw materials

[0089] The raw materials used in the examples and comparative examples are shown below.

[0090] (1) Dicarboxylic acid component

[0091] · TPA: Terephthalic acid

[0092] (2) Diamine component

[0093] · DDA: 1,10-Decanediamine

[0094] · NDA: 1,9-Nonanediamine

[0095] · MODA: 2-Methyl-1,8-octanediamine

[0096] (3) Monocarboxylic acid component

[0097] · STA: Stearic acid

[0098] (4) Polymerization catalyst

[0099] · SHP: Sodium hypophosphite monohydrate

[0100] (5) Semi-aromatic polyamide

[0101] · Polyamide 10T

[0102] [Step (i)]

[0103] Add 4560 parts by mass of TPA powder as the dicarboxylic acid component, 9 parts by mass of SHP as the polymerization catalyst, and 490 parts by mass of STA as the end-capping agent to a belt-type stirrer reaction apparatus. Under nitrogen sealing, use a double-helix type stirring blade and stir at a rotation speed of 30 rpm while heating to 170°C. Then, while maintaining the temperature at 170°C and the rotation speed at 30 rpm, use a liquid injection device to continuously add 4950 parts by mass of DDA heated to 100°C to the TPA powder at a rate of 33 parts by mass per minute over 2.5 hours (continuous liquid injection method) to obtain a reaction product. The molar ratio of the raw material monomers is DDA:TPA:STA = 49.6:47.4:3.0 (the equivalent ratio of the end groups of the raw material monomers is DDA:TPA:STA = 50.4:48.1:1.5).

[0104] [Step (ii)]

[0105] For the reaction product obtained in Step (i), then in the belt-type stirrer reaction apparatus used in Step (i), under a nitrogen stream, raise the temperature to 230°C and heat and polymerize at 230°C for 5 hours to obtain polyamide 10T.

[0106] The obtained polyamide 10T has a melting point of 317°C and a relative viscosity of 2.25.

[0107] · Polyamide 9T

[0108] Change the diamine component to NDA / MODA = 85 / 15 (molar ratio), and except for this, perform the same operations as in the case of manufacturing polyamide 10T to obtain polyamide 9T.

[0109] The obtained polyamide 9T has a melting point of 300°C and a relative viscosity of 2.31.

[0110] (6) Filler (B)

[0111] · Glass sheet A: REFG-315 manufactured by Nippon Sheet Glass Co., Ltd., average particle size 0.5 mm, average thickness 5 μm

[0112] · Glass sheet B: MEG160FY-M06 manufactured by Nippon Sheet Glass Co., Ltd., average particle size 0.16 mm, average thickness 0.7 μm

[0113] · Mica (muscovite): 300-D manufactured by Kuraray Co., Ltd.

[0114] · Glass fiber: T-262H manufactured by Nippon Electric Glass Co., Ltd., amino-silane treated product, fiber diameter 11 μm × fiber length 3 mm

[0115] · Carbon fiber: TR06NLB5K manufactured by Mitsubishi Chemical Corporation, fiber diameter 7 μm × fiber length 6 mm

[0116] · Wollastonite: SH-1250S manufactured by KINSEI MATEC Co., Ltd., amino-silane treated product, fiber diameter 8 μm, aspect ratio 15

[0117] · Calcium carbonate: P-70 manufactured by TOKYOFINE Chemical Co., Ltd.

[0118] (7) Polyphenylene ether (C)

[0119] · PPE PPO640 manufactured by SABIC

[0120] (8) Amorphous polyamide

[0121] · Grivory G21 manufactured by EMS-CHEMIE Japan

[0122] Example 1

[0123] 100 parts by mass of semi-aromatic polyamide (polyamide 10T) was supplied to the main supply port of a co-rotating twin-screw extruder (TEM37BS manufactured by Toshiba Machine Co., Ltd.) with a screw diameter of 37 mm and L / D of 40, and 100 parts by mass of a plate-shaped filler (glass sheet A) was supplied from the side feeder, followed by melt-kneading. The barrel temperature was (the melting point of polyamide 10T + 10 °C), the screw rotation speed was 250 rpm, and the discharge amount was 35 kg / hour. Then, it was taken out in a long strip shape and cooled and solidified through a water bath, and cut by a granulator to obtain polyamide resin composition particles.

[0124] Examples 2 to 17, 30 to 41, Comparative Examples 1 to 8

[0125] As shown in Tables 1 and 2, the composition of the resin composition was changed, and otherwise, the same operations as in Example 1 were carried out to obtain polyamide resin composition particles.

[0126] It should be noted that in Comparative Example 7, particles could not be obtained due to the large content of the filler.

[0127] Example 18

[0128] 100 parts by mass of semi-aromatic polyamide (polyamide 10T) and 25 parts by mass of polyphenylene ether were dry-blended to obtain a mixture.

[0129] The above mixture 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 of 40, and 125 parts by mass of a plate-shaped filler (glass sheet A) was fed from a side feeder, followed by melt-kneading. The barrel temperature was (the melting point of polyamide 10T + 10 °C), the screw rotation speed was 250 rpm, and the discharge rate was 35 kg / h. Then, it was taken out in a long strip shape, cooled and solidified in a water bath, and cut by a pelletizer to obtain polyamide resin composition pellets.

[0130] Examples 19 to 29, Comparative Example 9

[0131] As shown in Table 1, the resin composition was changed, and otherwise, the same operations as in Example 18 were carried out to obtain polyamide resin composition pellets.

[0132] The resin compositions and their characteristic values of the polyamide resin compositions obtained in the examples and comparative examples are shown in Tables 1 and 2.

[0133]

[0134]

[0135] The flexural strength of the polyamide resin compositions of Examples 1 to 41 was 100 MPa or more, the flexural modulus of elasticity was 10 GPa or more, and the mechanical properties were excellent. In addition, the linear expansion coefficient at 80 °C in either the flow direction (MD) or the orthogonal direction (TD) of the obtained molded body was 70×10 －6 (1 / °C) or less, and the dimensional stability was excellent. Furthermore, the weld line length was also 150 μm or less, and the moldability was excellent. Moreover, the water vapor transmission rate was also 150 mg or less, and the low moisture permeability was excellent.

[0136] 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 was found that even if the content of the filler was the same, if a plate-shaped filler and a fibrous filler were used in combination, the dimensional stability of the obtained molded body in either the flow direction (MD) or the orthogonal direction (TD) was improved.

[0137] By comparing Examples 1, 2, 4, 5, 11, 13 to 17 and Examples 18 to 27, it was found that if a part of polyamide 10T was changed to polyphenylene ether, the flexural strength became higher, the mechanical properties were improved, the linear expansion coefficient became lower, and the dimensional stability was improved.

[0138] The polyamide resin compositions of Comparative Examples 1 to 3 and 6 had low flexural strength, high linear expansion coefficient of the molded body, and long weld line length due to the low content of the filler.

[0139] In Comparative Examples 4 to 5, since only fibrous filler was used in the polyamide resin composition, the linear expansion coefficient in the TD direction of the molded body was high and the weld line length was long.

[0140] In Comparative Examples 8 and 9, since the mass ratio of the plate-like filler to the fibrous filler was not within the preferred range in the polyamide resin composition, the linear expansion coefficient in the TD direction of the molded body was high.

[0141] Symbol Explanation

[0142] 1: Test piece

[0143] 2: Filler

[0144] 3: Test fixture

[0145] 4: Test liquid.

Claims

1. A polyamide resin composition, characterized in that, it contains a semi-aromatic polyamide (A) and a plate-shaped filler and a fibrous filler as the filler (B), the total content of the plate-shaped filler and the fibrous filler is 100 to 250 parts by mass relative to 100 parts by mass of the semi-aromatic polyamide (A), and the mass ratio of the plate-shaped filler to the fibrous filler is 67 / 33 to 90 / 10, The linear expansion coefficient at 80 °C in the direction orthogonal to the resin flow direction during injection molding of the injection molded body is 60×10 －6 (1 / °C) or less.

2. A polyamide resin composition, characterized in that, it contains a semi-aromatic polyamide (A) and a filler (B), and the filler (B) is only a plate-shaped filler, the content of the plate-shaped filler is 100 to 250 parts by mass relative to 100 parts by mass of the semi-aromatic polyamide (A), The linear expansion coefficient at 80 °C in the direction orthogonal to the resin flow direction during injection molding of the injection molded body is 60×10 －6 (1 / °C) or less.

3. The polyamide resin composition according to claim 1 or 2, characterized in that, the length of the seam ridge generated at the position corresponding to the gas discharge part of the mold during injection molding in the injection molded body is 150 μm or less.

4. The polyamide resin composition according to claim 1, characterized in that, the plate-shaped filler is a glass sheet and the fibrous filler is glass fiber.

5. The polyamide resin composition according to claim 1, characterized in that, the plate-shaped filler is a glass sheet and the fibrous filler is carbon fiber.

6. The polyamide resin composition according to claim 1 or 2, characterized in that, the plate-shaped filler is a glass sheet.

7. The polyamide resin composition according to claim 1 or 2, characterized in that, it further contains 20 to 110 parts by mass of polyphenylene ether (C).

8. A molded body formed by molding the polyamide resin composition according to any one of claims 1 to 7.

9. A component for an in-vehicle camera, which is composed of the molded body according to claim 8.

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