Polyamide resin composition, molded article, molded article coating method, and article

Abstract

The purpose of the present invention is to provide a polyamide resin composition having excellent rigidity and impact resistance after absorbing water. This purpose is achieved by means of a polyamide resin composition containing (A) a crystalline semi-aromatic polyamide resin and (B) an aliphatic polyamide resin which comprises a diamine unit and a dicarboxylic acid unit and in which the ratio (C / N) of the number of carbon atoms (C) to the number of nitrogen atoms (N) included in a repeating unit is at least 7.0 and at most 10.0.

Description

Polyamide resin composition, molded article, method for coating a molded article, and article

[0001] The present invention relates to a polyamide resin composition, a molded article, a method for coating a molded article, and an article.

[0002] Plastic parts made from reinforced thermoplastic resins are widely used in automotive applications and electrical and electronic component applications. Among the plastic parts used in these applications, polyamide resins having excellent performance in terms of heat resistance, chemical resistance, mechanical strength, abrasion resistance, moldability, etc. are particularly widely used.

[0003] In recent years, in addition to the applications that have been widely used so far, plastic parts as metal substitutes have attracted attention in sports goods for the purpose of weight reduction.

[0004] For example, as sports goods, bicycles, tennis rackets, etc. are assumed to be instantaneously stressed, so high rigidity and high impact resistance are required for the plastic resin used. In addition, since many sports goods are used regardless of the climate, a resin that exhibits high mechanical strength in a wide range of use environments is desired.

[0005] Polyamide resins have been used in a wide range of applications from automotive applications and electrical and electronic component applications to sports goods applications because of their high heat resistance and mechanical strength. However, generally, polyamide has many hydrophilic amide groups in the molecule, so it is easy to absorb moisture, and the problems are that the mechanical strength decreases and the dimensional change rate is large after moisture absorption.

[0006] As disclosed in Patent Documents 1 and 2 below, the hygroscopicity is suppressed by using a long-chain polyamide or a copolymer containing a long-chain polyamide component. Also, regarding aromatic polyamides, the hygroscopicity can be relatively suppressed. Furthermore, a method for facilitating the processing of aromatic polyamides has also been disclosed (Patent Document 3).

[0007] JP-A-2009-215514, JP-T-2017-530228, Patent No. 6481181

[0008] However, suppressing hygroscopicity does not necessarily lead to an improvement in the retention of mechanical strength after moisture absorption, particularly in elastic modulus and impact resistance. Therefore, there is a need to develop polyamide resin compositions that improve elastic modulus and impact resistance after moisture absorption for use in a wide range of applications.

[0009] On the other hand, when long-chain polyamides are used to reduce water absorption, there are concerns about a decrease in rigidity. Furthermore, aromatic polyamides with rigid molecular chains have insufficient impact resistance, and a polyamide resin composition that achieves both of these conditions has not yet been found.

[0010] Therefore, the present invention aims to provide a polyamide resin composition and a molded article thereof that exhibits excellent rigidity and mechanical strength after water absorption.

[0011] The inventors of this invention conducted extensive research on polyamide resin compositions and discovered that by combining a crystalline semi-aromatic polyamide resin with a specific aliphatic polyamide resin, it is possible to suppress the decrease in rigidity and mechanical strength (elastic modulus and impact resistance) after water absorption, thus completing the present invention.

[0012] In other words, the present invention is as follows:

[0013] [1] A polyamide resin composition comprising: (A) a crystalline semi-aromatic polyamide resin; and (B) an aliphatic polyamide resin containing diamine units and dicarboxylic acid units, wherein the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in the repeating units (C / N) is 7.0 or more and 10.0 or less.

[0014] [2] The polyamide resin composition according to [1], wherein differential scanning calorimetry (DSC) shows at least two melting peaks, the difference (ΔTm) between the highest melting peak temperature (Tm-high) and the lowest melting peak temperature (Tm-low) among the at least two melting peaks is 90°C or more and 140°C or less, and the ratio [(ΔH-high):(ΔH-low)] of the enthalpy of melting of the melting peak at the highest melting peak temperature (ΔH-high) to the enthalpy of melting of the melting peak at the lowest melting peak temperature (ΔH-low), calculated from the area of ​​the melting peaks, is 5:1 to 2.3:1.

[0015] [3] The polyamide resin composition according to [2], wherein the highest melting peak temperature (Tm-high) among the at least two melting peaks is 325°C or higher.

[0016] [4] The polyamide resin composition according to any one of [1] to [3], wherein when the total mass of the (A) crystalline semi-aromatic polyamide resin and the (B) aliphatic polyamide resin is 100 parts by mass, the content of the (A) crystalline semi-aromatic polyamide resin is 55 parts by mass or more and 90 parts by mass or less.

[0017] [5] The polyamide resin composition according to any one of [1] to [4], wherein 80 mol% or more of the total dicarboxylic acid units constituting the (A) crystalline semi-aromatic polyamide resin are terephthalic acid units.

[0018] [6] The polyamide resin composition according to any one of [1] to [5], wherein the (A) crystalline semi-aromatic polyamide resin comprises an aliphatic diamine unit having 4 to 6 carbon atoms and a terephthalic acid unit.

[0019] [7] The polyamide resin composition according to [6], wherein the (A) crystalline semi-aromatic polyamide resin comprises tetramethylenediamine units and terephthalic acid units.

[0020] [8] The polyamide resin composition according to [2], wherein the lowest melting peak temperature (Tm-low) is 200°C or higher and 250°C or lower, and the melting enthalpy (ΔH-low) of the melting peak at the lowest melting peak temperature is 5 J / g or higher.

[0021] [9] The polyamide resin composition according to any one of [1] to [8], further comprising (C) polyphenylene ether, wherein the content of (C) polyphenylene ether is 5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the total mass of the (A) crystalline semi-aromatic polyamide resin and the (B) aliphatic polyamide resin containing diamine units and dicarboxylic acid units.

[0022]

[10] The polyamide resin composition according to [9], wherein the polyphenylene ether is a maleic anhydride-modified polyphenylene ether.

[0023]

[11] A polyamide resin composition comprising: (A) a crystalline semi-aromatic polyamide resin; (B) an aliphatic polyamide resin containing diamine units and dicarboxylic acid units, wherein the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in the repeating units (C / N) is 7.0 or more and 10.0 or less; and (C) a polyphenylene ether, wherein when the total mass of the crystalline semi-aromatic polyamide resin (A) and the aliphatic polyamide resin (B) is 100 parts by mass, the content of the crystalline semi-aromatic polyamide resin (A) is 50 parts by mass or more and 90 parts by mass or less; the content of the aliphatic polyamide resin (B) is 10 parts by mass or more and 50 parts by mass or less; and the content of the polyphenylene ether (C) is 5 parts by mass or more and 30 parts by mass or less with respect to the total mass of the crystalline semi-aromatic polyamide resin (A) and the aliphatic polyamide resin (B) of 100 parts by mass.

[0024]

[12] The polyamide resin composition according to

[11] , further comprising (D) an olefin copolymer modified with an acid component, wherein the content of the olefin copolymer modified with the acid component (D) is 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the total mass of the (A) crystalline semi-aromatic polyamide resin and the (B) aliphatic polyamide resin.

[0025]

[13] The polyamide resin composition according to

[11] or

[12] , further comprising (E) an inorganic filler, wherein the amount of (E) the inorganic filler is 10 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the total mass of the (A) crystalline semi-aromatic polyamide resin and the (B) aliphatic polyamide resin.

[0026]

[14] A molded article comprising a polyamide resin composition as described in any of

[11] to

[13] , wherein the surface roughness is 3 μm or more and 10 μm or less.

[0027]

[15] A molded article comprising a polyamide resin composition as described in any of

[11] to

[14] , which is used for bicycle frame parts, racket frame parts, or fishing reel parts.

[0028]

[16] An article having a molded article containing a polyamide resin composition according to any one of

[11] to

[15] , and a coating film made of a coated paint.

[0029]

[17] A method for painting a molded article, comprising the step of applying paint to a molded article containing a polyamide resin composition according to any one of

[11] to

[16] .

[0030] According to the present invention, it is possible to provide a polyamide resin composition and a molded article thereof that exhibits excellent flexural modulus and mechanical strength when water is absorbed.

[0031] The following describes in detail embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment"). This embodiment is illustrative for explaining the present invention and is not intended to limit the present invention to the following content. The present invention can be implemented by modifying it as appropriate within the scope of its gist.

[0032] [Definition] In this specification, "polyamide" means a polymer having an amide group (-NHCO-) ​​in its main chain.

[0033] In this specification, "semi-aromatic polyamide" means a polyamide having aliphatic units and aromatic units. Aliphatic units refer to units derived from aliphatic monomers. Aromatic units refer to units derived from aromatic monomers.

[0034] Unless otherwise specified, the materials, components, compounds, resins, and solvents described herein may be used individually or in combination of two or more.

[0035] In this specification, unless otherwise stated, numerical ranges are intended to include the upper and lower limits of that range. For example, 90 to 100 mol% means the range of 90 mol% or more and 100 mol% or less.

[0036] In this specification, the melting peak temperature Tm and the enthalpy of melting ΔH are values ​​measured using a differential scanning calorimeter (DSC) (e.g., a Diamond-DSC manufactured by Perkin-Elmer) with reference to JIS-K 7121. The measurement conditions are as follows: under a nitrogen atmosphere, approximately 10 mg of the polyamide resin composition is heated at a heating rate of 20°C / min to 200°C to 370°C depending on the melting point (Tm) of the sample (during the first heating). The melting peak temperature that appears on the lowest temperature side of the endothermic peak (melting peak) is defined as the lowest melting peak temperature (Tm-low) (°C), and the melting peak temperature that appears on the highest temperature side is defined as the highest melting peak temperature (Tm-high) (°C). The enthalpy of melting ΔH is calculated from the area of ​​these melting peaks.

[0037] In this specification, (A) the tanδ peak temperature of the crystalline semi-aromatic polyamide resin is a value measured using a viscoelasticity analyzer (e.g., Rheology DVE-V4) under the following conditions: (Measurement conditions) Measurement mode: Tensile Measurement Frequency: 8.00 Hz Heating rate: 3°C / min Temperature range: -100°C or higher and 250°C or lower The ratio of the storage modulus E1 and the loss modulus E2 (E2 / E1) measured by the above method is defined as tanδ, and the temperature of the highest tanδ is defined as the tanδ peak temperature.

[0038] In this embodiment, the melting peak temperature of the polyamide resin composition is the value measured by the measurement method described in the example.

[0039] [Polyamide Resin Composition] The polyamide resin composition according to the first embodiment and the polyamide resin composition according to the second embodiment will be described below.

[0040] (Polyamide resin composition according to the first embodiment) The polyamide resin composition according to the first embodiment is characterized by containing (A) a crystalline semi-aromatic polyamide resin and (B) an aliphatic polyamide resin containing diamine units and dicarboxylic acid units, wherein the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in the repeating units (C / N) is 7.0 or more and 10.0 or less (hereinafter sometimes simply referred to as "(B) aliphatic polyamide resin"). The polyamide resin composition according to the first embodiment has excellent rigidity and mechanical strength after water absorption. Furthermore, molded articles with small dimensional changes due to water absorption can be obtained from the polyamide resin composition.

[0041] The polyamide resin composition according to the first embodiment preferably has at least two melting peaks in differential scanning calorimetry (DSC). Of these at least two melting peaks, the temperature of the highest melting peak is referred to as the highest melting peak temperature (Tm-high), and the temperature of the lowest melting peak is referred to as the lowest melting peak temperature (Tm-low).

[0042] Of the melting peaks of the polyamide resin composition according to the first embodiment, the highest melting peak temperature (Tm-high) is preferably 325°C or higher, more preferably 330°C or higher, even more preferably 335°C or higher, and particularly preferably 340°C or higher. The upper limit of Tm-high is not particularly limited, but can be 380°C or lower, 370°C or lower, 360°C or lower, and 350°C or lower. These upper and lower limits can be arbitrarily combined.

[0043] Methods for adjusting the highest melting peak temperature (Tm-high) include, but are not limited to, using a high-melting-point polyamide as the (A) crystalline semi-aromatic polyamide resin, for example, a polyamide with a melting point of 325°C or higher. Specific (A) crystalline semi-aromatic polyamide resins that are preferably used will be described later.

[0044] Among the melting peaks of the polyamide resin composition according to the first embodiment, the lowest melting peak temperature (Tm-low) is preferably 200°C or higher. Further, the lowest melting peak temperature (Tm-low) is preferably 250°C or lower, more preferably 240°C or lower, and even more preferably 230°C or lower. That is, the lowest melting peak temperature (Tm-low) is preferably 200°C or higher and 250°C or lower, more preferably 200°C or higher and 240°C or lower, and even more preferably 200°C or higher and 230°C or lower.

[0045] Among at least two melting peaks of the polyamide resin composition, the difference (ΔTm) between the highest melting peak temperature (Tm-high) and the lowest melting peak temperature (Tm-low) is preferably 90°C or higher and 140°C or lower, more preferably 95°C or higher and 138°C or lower, even more preferably 100°C or higher and 135°C or lower, further preferably 105°C or higher and 132°C or lower, and particularly preferably 110°C or higher and 130°C or lower.

[0046] As a method for adjusting the difference (ΔTm) between the highest melting peak temperature (Tm-high) and the lowest melting peak temperature (Tm-low), (A) a crystalline semi-aromatic polyamide resin and (B) an aliphatic polyamide resin can be appropriately selected, but it is not limited thereto. Specific (A) crystalline semi-aromatic polyamide resins and (B) aliphatic polyamide resins containing diamine units and dicarboxylic acid units that are preferably used will be described later.

[0047] Among at least two melting peaks of the polyamide resin composition, the melting enthalpy (ΔH-low) of the melting peak at the lowest melting peak temperature is preferably 5.0 J / g or higher, and preferably 10.0 J / g or lower, and more preferably 8.0 J / g or lower. These upper and lower limits can be appropriately combined.

[0048] Furthermore, the enthalpy of melting (ΔH-high) of the melting peak at the highest melting peak temperature among the at least two melting peaks of the polyamide resin composition is preferably 10 J / g or more, more preferably 15 J / g or more, preferably 30 J / g or less, and more preferably 25 J / g or less. These upper and lower limits can be combined as appropriate.

[0049] The ratio of the enthalpies of fusion calculated from the area of ​​the melting peaks at the highest melting peak temperature (Tm-high) and the lowest melting peak temperature (Tm-low) among the at least two melting peaks of the polyamide resin composition [(ΔH-high):(ΔH-low)] is preferably 5:1 to 2.3:1, more preferably 4.5:1 to 2.3:1, even more preferably 4.0:1 to 2.4:1, and particularly preferably 3.5:1 to 2.5:1.

[0050] The fact that the melting peak temperature, the difference between the two melting peak temperatures, and the ratio of their respective melting enthalpies are within the above range suggests that each component grows sufficiently as a single-component crystal without inhibiting the crystallization of the others, resulting in a polyamide resin composition with excellent rigidity and impact resistance when water is absorbed.

[0051] Methods for adjusting [(ΔH-high):(ΔH-low)] to within the above range include, but are not limited to, appropriately selecting the content ratio of (A) crystalline semi-aromatic polyamide resin and (B) aliphatic polyamide resin. Specific examples of (A) crystalline semi-aromatic polyamide resin and (B) aliphatic polyamide resin containing diamine units and dicarboxylic acid units that are preferably used will be described later.

[0052] The following describes in detail each component constituting the polyamide resin composition according to the first embodiment.

[0053] <(A) Crystalline semi-aromatic polyamide resin> The (A) crystalline semi-aromatic polyamide resin is not particularly limited as long as it is a crystalline polyamide, but from the viewpoint of appropriately adjusting Tm-high, it is preferable that it has a melting point of 325°C or higher, more preferably 330°C or higher, even more preferably 335°C or higher, and particularly preferably 340°C or higher. The melting point of the (A) crystalline semi-aromatic polyamide resin is determined by performing differential scanning calorimetry with reference to the method described in JIS-K 7121.

[0054] Because the melting point of the crystalline semi-aromatic polyamide resin (A) is above the lower limit, the heat resistance of the molded article obtained from the polyamide resin composition tends to be superior.

[0055] (A) The crystalline semi-aromatic polyamide resin is preferably a semi-aromatic polyamide resin comprising (I) aliphatic diamine units having a linear hydrocarbon chain (including a skeleton with side chains) and (II) dicarboxylic acid units having at least one aromatic ring in the molecule.

[0056] The aliphatic diamine units having a linear hydrocarbon chain (including a skeleton with side chains) preferably include aliphatic diamine units having 4 to 12 carbon atoms, more preferably include aliphatic diamine units having 4 to 10 carbon atoms, and particularly preferably include aliphatic diamine units having 4 to 6 carbon atoms. When the number of carbon atoms of the aliphatic diamine units is within the above range, the retention rate of physical properties when the polyamide resin composition absorbs water tends to be better.

[0057] The aliphatic diamine may be used alone or in combination of two or more types.

[0058] The dicarboxylic acid unit having at least one aromatic ring in the molecule (II) preferably includes a dicarboxylic acid unit having 8 to 14 carbon atoms, and is particularly preferably a terephthalic acid unit. The inclusion of a terephthalic acid unit tends to result in better retention of physical properties of the polyamide resin composition after water absorption.

[0059] The dicarboxylic acid units having at least one aromatic ring within the molecule (II) preferably consist of terephthalic acid units in an amount of 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 100 mol% of the total number of moles of dicarboxylic acid units constituting the crystalline semi-aromatic polyamide resin (A). In other words, of the total dicarboxylic acid units constituting the crystalline semi-aromatic polyamide resin (A), preferably consist of terephthalic acid units in an amount of 50 mol% or more, more preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 100 mol%.

[0060] The dicarboxylic acid unit having at least one aromatic ring in the molecule (II) may include dicarboxylic acid units other than terephthalic acid units, to the extent that its effect is not impaired. The other dicarboxylic acid units are preferably aromatic dicarboxylic acid units, and for example, dicarboxylic acid units having a benzene ring skeleton or a naphthalene skeleton are particularly preferred.

[0061] The aromatic ring portion of the aromatic dicarboxylic acid unit may be unsubstituted or may have substituents. Substituents are not particularly limited, but examples include alkyl groups having 1 to 4 carbon atoms, aryl groups having 6 to 10 carbon atoms, aralkyl groups having 7 to 10 carbon atoms, halogen groups such as chloro and bromo groups, silyl groups having 1 to 6 carbon atoms, sulfonic acid groups and their salts (such as sodium salts).

[0062] The aromatic dicarboxylic acids constituting the aromatic dicarboxylic acid unit may be used individually or in combination of two or more types.

[0063] The (A) crystalline semi-aromatic polyamide resin is preferably a polyamide resin containing aliphatic diamine units having 4 to 12 carbon atoms and dicarboxylic acid units having at least one aromatic ring in the molecule and having 8 to 14 carbon atoms; more preferably a polyamide resin containing aliphatic diamine units having 4 to 6 carbon atoms and dicarboxylic acid units having 8 to 14 carbon atoms; even more preferably a polyamide resin containing aliphatic diamine units having 4 to 6 carbon atoms and terephthalic acid units; and preferably a semi-aromatic polyamide resin containing a polyamide 6T (PA6T) repeating structure mainly composed of hexamethylenediamine and terephthalic acid, or a semi-aromatic polyamide resin containing a polyamide 4T (PA4T) repeating structure mainly composed of tetramethylenediamine and terephthalic acid. Particularly preferred is a semi-aromatic polyamide resin containing a polyamide 4T (PA4T) repeating structure mainly composed of tetramethylenediamine and terephthalic acid, i.e., a polyamide resin containing tetramethylenediamine units and terephthalic acid units.

[0064] The tanδ peak temperature of the crystalline semi-aromatic polyamide resin (A) is preferably 80°C or higher, more preferably 90°C to 160°C, even more preferably 100°C to 155°C, particularly preferably 110°C to 150°C, and most preferably 120°C to 150°C. When the tanδ peak temperature of the crystalline semi-aromatic polyamide resin (A) is above the lower limit, the heat resistance and retention of physical properties when water is absorbed of the molded article obtained from the polyamide resin composition tend to be superior.

[0065] Furthermore, in the polyamide resin composition according to the first embodiment, the content of (A) crystalline semi-aromatic polyamide resin is preferably 50 parts by mass or more and 99 parts by mass or less, more preferably 55 parts by mass or more and 90 parts by mass or less, and particularly preferably 60 parts by mass or more and 85 parts by mass or less, based on 100 parts by mass of the total mass of (A) crystalline semi-aromatic polyamide resin and (B) aliphatic polyamide resin.

[0066] <(B) Aliphatic Polyamide Resin> The polyamide resin composition according to the first embodiment includes an aliphatic polyamide resin comprising (B) diamine units and dicarboxylic acid units, wherein the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in the repeating units (C / N) is 7.0 or more and 10.0 or less. The aliphatic polyamide resin comprising (B) diamine units and dicarboxylic acid units, wherein the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in the repeating units (C / N) is 7.0 or more and 10.0 or less, is not limited to, but is preferably an aliphatic polyamide resin comprising (III) aliphatic diamine units having a linear hydrocarbon chain (including a skeleton with side chains) and (IV) aliphatic dicarboxylic acid units.

[0067] (B) The aliphatic polyamide resin preferably has a melting point 90°C to 140°C lower than the melting point of (A) the crystalline semi-aromatic polyamide, more preferably 95°C to 138°C lower, even more preferably 100°C to 135°C lower, particularly preferably 105°C to 132°C lower, and most preferably 110°C to 130°C lower, from the viewpoint of appropriately adjusting the difference (ΔTm) between Tm-high and Tm-low of the polyamide resin composition.

[0068] The aliphatic diamine unit having a (III) linear hydrocarbon chain (including a skeleton with side chains) preferably includes aliphatic diamine units having 4 to 12 carbon atoms, more preferably includes aliphatic diamine units having 4 to 10 carbon atoms, and particularly preferably includes aliphatic diamine units having 4 to 6 carbon atoms.

[0069] Examples of the (IV) aliphatic dicarboxylic acid units include linear or branched saturated aliphatic dicarboxylic acid units having 3 to 20 carbon atoms, and linear or branched unsaturated aliphatic dicarboxylic acid units having 6 to 20 carbon atoms. Among these, linear saturated aliphatic dicarboxylic acids having 8 to 15 carbon atoms are particularly preferred from the viewpoint of the heat resistance of the polyamide resin composition.

[0070] (B) In the aliphatic polyamide resin, from the viewpoint of heat resistance, impact resistance, and retention of physical properties when water is absorbed, the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) contained in the repeating unit of the polyamide (C / N) is preferably 7.0 to 10.0, more preferably 7.0 to 9.0, and more preferably 7.0 to 8.0.

[0071] (B) The aliphatic polyamide resin is preferably a polyamide containing aliphatic diamine units having 4 to 6 carbon atoms and aliphatic dicarboxylic acid units having 8 to 15 carbon atoms, from the viewpoint of heat resistance, impact resistance, retention of physical properties when water is absorbed and low water absorption dimensional change rate of molded articles, more preferably polyamide 410 (PA410) or polyamide 610 (PA610), and even more preferably PA610.

[0072] Furthermore, the ends of the polyamide resins ((A) crystalline semi-aromatic polyamide resin and (B) aliphatic polyamide resin) contained in the polyamide resin composition may be sealed with a known end-capturing agent.

[0073] In the polyamide resin composition according to the first embodiment, the content of (B) aliphatic polyamide resin is preferably 1 to 50 parts by mass, more preferably 10 to 45 parts by mass, even more preferably 10 to 50 parts by mass, and particularly preferably 15 to 40 parts by mass, based on 100 parts by mass of the total mass of (A) crystalline semi-aromatic polyamide resin and (B) aliphatic polyamide resin.

[0074] <(C) Polyphenylene Ether> The polyamide resin composition according to the first embodiment preferably further contains (C) polyphenylene ether. In the present invention, (C) polyphenylene ether may be modified or unmodified. That is, (C) polyphenylene ether may be modified polyphenylene ether or unmodified polyphenylene ether. Furthermore, (C) polyphenylene ether may be a single type or a combination of two or more types.

[0075] (C) Polyphenylene ether is preferably a modified polyphenylene ether, and more preferably an acid-modified polyphenylene ether modified with an acid. The acid-modified polyphenylene ether is not particularly limited, but those modified with dicarboxylic acids such as maleic acid and itaconic acid, or their anhydrides, are preferred in that they have superior mechanical strength. Specifically, (C) polyphenylene ether is preferably maleic acid-modified polyphenylene ether, itaconic acid-modified polyphenylene ether, maleic anhydride-modified polyphenylene ether, itaconic anhydride-modified polyphenylene ether, or fumaric acid-modified polyphenylene ether. Among these, maleic anhydride-modified polyphenylene ether, which is a polyphenylene ether modified with maleic anhydride, is particularly preferred.

[0076] (C) The polyphenylene ether in polyphenylene ether is not limited, but homopolymers are preferred, for example, poly(2,6-dimethyl-1,4-phenylene ether), poly(2-methyl-6-ethyl-1,4-phenylene ether), poly(2-methyl-6-phenyl-1,4-phenylene ether), poly(2,6-dichloro-1,4-phenylene ether), etc.

[0077] (C) The content of polyphenylene ether is preferably 5 parts by mass or more and 30 parts by mass or less, more preferably 7 parts by mass or more and 25 parts by mass or less, and even more preferably 10 parts by mass or more and 20 parts by mass or less, based on 100 parts by mass of the total mass of (A) crystalline semi-aromatic polyamide resin and (B) aliphatic polyamide resin. When the content of (C) acid-modified polyphenylene ether is within the above range, the rigidity and impact resistance of the polyamide resin composition when it absorbs moisture tend to be better.

[0078] <(D) Olefin copolymer modified by acid component> In addition to the above components, the polyamide resin composition according to the first embodiment may contain an olefin copolymer modified by an acid component (D) that is conventionally used in polyamide resin compositions (hereinafter sometimes referred to as "(D) acid-modified olefin copolymer"), to the extent that it does not impair the effects of the polyamide resin composition.

[0079] As the (D) acid-modified olefin copolymer, those modified with dicarboxylic acids such as maleic acid and itaconic acid, or their anhydrides, are preferred in that they have superior mechanical properties.

[0080] The (D) acid-modified olefin copolymer has at least one component derived from an olefin compound as its constituent elements. The main chain of the olefin copolymer is preferably an unsaturated hydrocarbon structure and / or a saturated hydrocarbon structure obtained by reducing the unsaturated hydrocarbon, and can be represented by CmHn (where m and n are natural numbers).

[0081] The (D) acid-modified copolymer does not have the molecular structure contained in the polyamides of the (A) crystalline semi-aromatic polyamide resin and the (B) aliphatic polyamide resin, and is preferably one that has been modified with maleic anhydride, such as ethylene vinyl acetate (EVA), ethylene acrylate copolymer (EEA), styrene-ethylene butylene-styrene copolymer (SEBS), or styrene-ethylene propylene-styrene copolymer (SEPS). These acid-modified copolymers may be used individually or in combination of two or more.

[0082] Furthermore, if the polyamide resin composition contains the (D) acid-modified olefin copolymer, the content is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 1.0 part by mass or more and 30 parts by mass or less, even more preferably 1.0 part by mass or more and 20 parts by mass or less, particularly preferably 2.0 parts by mass or more and 15 parts by mass or less, and most preferably 3.0 parts by mass or more and 10 parts by mass or less, based on 100 parts by mass of the total mass of the (A) crystalline semi-aromatic polyamide resin and the (B) aliphatic polyamide resin.

[0083] <(E) Inorganic filler> In addition to the above components, the polyamide resin composition according to the first embodiment may contain (E) an inorganic filler, to the extent that it does not impair the effects of the invention.

[0084] (E) The inorganic filler is not particularly limited, but it is preferably a fibrous inorganic filler, and is especially preferably glass fiber or carbon fiber. By including the above-mentioned fibrous inorganic filler, it is possible to obtain a polyamide resin composition with excellent mechanical strength. These inorganic fillers may be used individually or in combination of two or more types.

[0085] The polyamide resin composition may also contain inorganic fillers other than the fibrous inorganic filler. For example, inorganic fillers other than the fibrous inorganic filler are not limited to talc, mica, wollastonite, kaolin, hydrotalcite, glass flakes, calcium carbonate, zinc oxide, silica, alumina, titanium oxide, carbon nanotubes, graphite, aluminum, iron, etc.

[0086] When the polyamide resin composition according to the first embodiment contains the inorganic filler (E), its content is preferably 10 parts by mass or more and 100 parts by mass or less, more preferably 15 parts by mass or more and 80 parts by mass or less, even more preferably 20 parts by mass or more and 70 parts by mass or less, particularly preferably 25 parts by mass or more and 60 parts by mass or less, and most preferably 30 parts by mass or more and 50 parts by mass or less, based on 100 parts by mass of the total mass of the crystalline semi-aromatic polyamide resin (A) and the aliphatic polyamide resin (B). When the content of the inorganic filler (E) is within the above range, it tends to be possible to obtain a polyamide resin composition that achieves both flexural modulus and impact resistance.

[0087] <(F) Other Components> In addition to the components described above, the polyamide resin composition according to the first embodiment may also contain (F) other components that are conventionally used in polyamide resin compositions, to the extent that they do not impair the effects of the present invention.

[0088] Examples of the (F) other components include (A) crystalline semi-aromatic polyamide resins and (B) polyamide resins other than aliphatic polyamide resins, (C) polyphenylene ethers, (D) resin components other than olefin copolymers modified by acid components, moldability improvers, degradation inhibitors, heat stabilizers, nucleating agents, dyes and pigments for coloring, etc.

[0089] Furthermore, if the polyamide resin composition according to the first embodiment contains the other component (F), the content of the other component (F) in the polyamide resin composition of this embodiment varies depending on its type and the intended use of the polyamide resin composition, and is therefore not particularly limited as long as it does not impair the effects of the polyamide resin composition of this embodiment. For example, as individual components, the content can be 0 parts by mass or more and 5 parts by mass or less, 0.1 parts by mass or more and 3.0 parts by mass or less, 0.2 parts by mass or more and 2.0 parts by mass or less, and 0.3 parts by mass or more and 1.0 part by mass or less, based on 100 parts by mass of the total mass of the crystalline semi-aromatic polyamide resin (A) and the aliphatic polyamide resin (B). Furthermore, the total content of (F) other components may be 0 parts by mass or more and 50 parts by mass or less, 0.1 parts by mass or more and 40 parts by mass or less, 0.2 parts by mass or more and 30 parts by mass or less, 0.3 parts by mass or more and 25 parts by mass or less, 0.4 parts by mass or more and 20 parts by mass or less, and 0.5 parts by mass or more and 15 parts by mass or less, based on 100 parts by mass of the total mass of (A) crystalline semi-aromatic polyamide resin and (B) aliphatic polyamide resin.

[0090] (Polyamide resin composition according to the second embodiment) The polyamide resin composition according to the second embodiment contains: (A) a crystalline semi-aromatic polyamide resin; (B) an aliphatic polyamide resin containing diamine units and dicarboxylic acid units, wherein the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in the repeating units (C / N) is 7.0 or more and 10.0 or less; and (C) a polyphenylene ether, wherein when the total mass of the crystalline semi-aromatic polyamide resin (A) and the aliphatic polyamide resin (B) is 100 parts by mass, the content of the crystalline semi-aromatic polyamide resin (A) is 50 parts by mass or more and 90 parts by mass or less; the content of the aliphatic polyamide resin (B) is 10 parts by mass or more and 50 parts by mass or less; and the content of the polyphenylene ether (C) is 5 parts by mass or more and 30 parts by mass or less with respect to the total mass of the crystalline semi-aromatic polyamide resin (A) and the aliphatic polyamide resin (B) is 100 parts by mass or more and 30 parts by mass or less. The polyamide resin composition according to the second embodiment exhibits excellent flexural modulus and mechanical strength when water is absorbed. Furthermore, the polyamide resin composition according to the second embodiment also exhibits excellent paintability when molded into a product.

[0091] The polyamide resin composition according to the second embodiment preferably has at least two melting peaks in differential scanning calorimetry (DSC). Of these at least two melting peaks, the temperature of the highest melting peak is referred to as the highest melting peak temperature (Tm-high), and the temperature of the lowest melting peak is referred to as the lowest melting peak temperature (Tm-low).

[0092] The polyamide resin composition preferably exhibits a highest melting peak temperature (Tm-high) of at least two melting peaks in differential scanning calorimetry (DSC) measurements of 300°C or higher. More preferably, the highest melting peak temperature (Tm-high) is 310°C or higher, even more preferably 320°C or higher, and particularly preferably 330°C or higher. The upper limit of the highest melting peak temperature (Tm-high) is not particularly limited, but can be 380°C or lower, 370°C or lower, 360°C or lower, or 350°C or lower. These upper and lower limits can be combined arbitrarily.

[0093] Methods for adjusting the highest melting peak temperature (Tm-high) include, but are not limited to, using a high-melting-point polyamide as the (A) crystalline semi-aromatic polyamide resin, for example, a polyamide with a melting point of 300°C or higher. Specific (A) crystalline semi-aromatic polyamide resins that are preferably used will be described later.

[0094] In the polyamide resin composition according to the second embodiment, the lowest melting peak temperature (Tm-low) among at least two melting peaks is preferably 200°C or higher and 250°C or lower, more preferably 240°C or lower, and even more preferably 230°C or lower.

[0095] In the polyamide resin composition according to the second embodiment, the difference between the highest melting peak temperature (Tm-high) and the lowest melting peak temperature (Tm-low) among the at least two melting peaks is preferably 80°C to 160°C, more preferably 85°C to 150°C, even more preferably 90°C to 140°C, and particularly preferably 110°C to 130°C. Furthermore, the above difference can be 95°C to 138°C, 100°C to 135°C, or 105°C to 132°C.

[0096] Methods for adjusting the difference between Tm-high and Tm-low include, but are not limited to, appropriately selecting (A) a crystalline semi-aromatic polyamide resin and (B) an aliphatic polyamide resin. Specific examples of (A) semi-aromatic polyamide resins and (B) aliphatic polyamide resins that are preferably used will be described later.

[0097] The polyamide resin composition has at least two melting peaks, and the temperature difference between the highest melting peak temperature (Tm-high) and the lowest melting peak temperature (Tm-low) is within the above range, which suggests that each component can grow sufficiently as a single component crystal without inhibiting the crystallization of the others. As a result, the polyamide resin composition tends to have excellent flexural modulus and impact resistance after water absorption.

[0098] The enthalpy of melting (ΔH-low), calculated from the area of ​​the lowest melting peak temperature (Tm-low) among the at least two melting peaks of the polyamide resin composition, is preferably 3.0 J / g or more, more preferably 3.1 J / g or more, even more preferably 3.2 J / g or more, and particularly preferably 3.3 J / g or more. The upper limit of the enthalpy of melting (ΔH-low), calculated from the area of ​​the lowest melting peak temperature (Tm-low), is not particularly limited, but can be 6 J / g or less, 5.5 J / g or less, and 5 J / g or less. Furthermore, the polyamide resin composition preferably has a minimum melting peak temperature (Tm-low) of 200°C or higher and a melting enthalpy (ΔH-low) calculated from the peak area of ​​250°C or higher, and more preferably has a minimum melting peak temperature (Tm-low) of 200°C or higher and a melting enthalpy (ΔH-low) calculated from the peak area of ​​3.3 J / g or higher.

[0099] The components of the polyamide resin composition according to the second embodiment will be described below.

[0100] <(A) Crystalline semi-aromatic polyamide resin> The (A) crystalline semi-aromatic polyamide resin is not particularly limited as long as it is a crystalline polyamide, but from the viewpoint of appropriately adjusting the highest melting peak temperature (Tm-high), it is preferable to have a melting point of 300°C or higher, more preferably 310°C or higher, even more preferably 325°C or higher, and particularly preferably 330°C or higher. The melting point of the (A) crystalline semi-aromatic polyamide resin can be measured using a differential scanning calorimeter, referring to JIS-K 7121.

[0101] The tanδ peak temperature of the crystalline semi-aromatic polyamide resin (A) is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher.

[0102] Because the melting point and tanδ peak temperature of the crystalline semi-aromatic polyamide resin (A) are within the above temperature range, the molded articles obtained from the polyamide resin composition tend to have better heat resistance and better mechanical properties when humidified.

[0103] The (A) crystalline semi-aromatic polyamide resin of this embodiment is preferably a semi-aromatic polyamide resin comprising (I) aliphatic diamine units having a linear hydrocarbon chain (including a skeleton with side chains) and (II) dicarboxylic acid units having at least one aromatic ring in the molecule. The semi-aromatic polyamide resin comprising (I) aliphatic diamine units having a linear hydrocarbon chain (including a skeleton with side chains) and (II) dicarboxylic acid units having at least one aromatic ring in the molecule is the same as those in the polyamide resin composition of the first embodiment described above, and the explanation in the section on the polyamide resin composition of the first embodiment will be used with reference.

[0104] Furthermore, in the polyamide resin composition of this embodiment, the content of (A) crystalline semi-aromatic polyamide resin is preferably 50 parts by mass or more and 90 parts by mass, more preferably 52 parts by mass or more and 88 parts by mass, more preferably 55 parts by mass or more and 85 parts by mass, and even more preferably 57 parts by mass or more and 80 parts by mass, based on 100 parts by mass of the total mass of (A) crystalline semi-aromatic polyamide resin and (B) aliphatic polyamide resin, from the viewpoint of flexural modulus after water absorption and impact resistance.

[0105] <(B) Aliphatic Polyamide Resin> The polyamide resin composition according to the second embodiment includes an aliphatic polyamide resin comprising (B) diamine units and dicarboxylic acid units, wherein the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in the repeating units (C / N) is 7.0 or more and 10.0 or less. The aliphatic polyamide resin comprising (B) diamine units and dicarboxylic acid units, wherein the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in the repeating units (C / N) is 7.0 or more and 10.0 or less, is not limited to, but is preferably an aliphatic polyamide resin comprising (III) aliphatic diamine units having a linear hydrocarbon chain (including a skeleton with side chains) and (IV) aliphatic dicarboxylic acid units.

[0106] (B) The aliphatic polyamide resin preferably has a melting point 80°C to 160°C lower than the melting point of (A) the crystalline semi-aromatic polyamide, more preferably 85°C to 150°C lower, even more preferably 90°C to 140°C lower, and particularly preferably 110°C to 130°C lower, from the viewpoint of appropriately adjusting the difference between the highest melting peak temperature (Tm-high) and the lowest melting peak temperature (Tm-low). (B) The aliphatic polyamide resin may have a melting point 95°C to 138°C, 100°C to 135°C, or 105°C to 132°C lower than the melting point of (A) the crystalline semi-aromatic polyamide.

[0107] In the polyamide resin composition according to the second embodiment, the content of (B) aliphatic polyamide resin is 10 parts by mass or more and 50 parts by mass or less, preferably 12 parts by mass or more and 48 parts by mass or less, more preferably 15 parts by mass or more and 45 parts by mass or less, and even more preferably 20 parts by mass or more and 43 parts by mass or less, based on 100 parts by mass of the total mass of (A) crystalline semi-aromatic polyamide resin and (B) aliphatic polyamide resin.

[0108] In the polyamide resin composition according to the second embodiment, the (B) aliphatic polyamide resin is the same as the (B) aliphatic polyamide resin in the polyamide resin composition according to the first embodiment described above. The (III) aliphatic diamine units having linear hydrocarbon chains (including a skeleton with side chains), the (IV) aliphatic dicarboxylic acid units, the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in the repeating units of the polyamide (C / N), and preferred examples of the (B) aliphatic polyamide resin are the same as the (B) aliphatic polyamide resin in the polyamide resin composition according to the first embodiment described above. Therefore, the explanation of the (B) aliphatic polyamide resin in the polyamide resin composition according to the first embodiment described above will be used by reference.

[0109] <(C) Polyphenylene Ether> The polyamide resin composition according to the second embodiment contains (C) polyphenylene ether. The content of (C) polyphenylene ether is 5 parts by mass or more and 30 parts by mass or less, preferably 7 parts by mass or more and 25 parts by mass or less, and more preferably 10 parts by mass or more and 20 parts by mass or less, based on 100 parts by mass of the total mass of (A) crystalline semi-aromatic polyamide resin and (B) aliphatic polyamide resin. When the content of (C) polyphenylene ether is within the above range, the rigidity and impact resistance of the polyamide resin composition when it absorbs moisture tend to be better.

[0110] The (C) polyphenylene ether in the polyamide resin composition according to the second embodiment is the same as the (C) polyphenylene ether in the polyamide resin composition according to the first embodiment. Therefore, the explanation of the (C) polyphenylene ether in the polyamide resin composition according to the first embodiment will be used with reference.

[0111] <(D) Olefin copolymer modified by acid component> The polyamide resin composition according to the second embodiment preferably further contains an olefin copolymer modified by an acid component (D). The olefin copolymer modified by an acid component (D) in the polyamide resin composition according to the second embodiment is the same as the olefin copolymer modified by an acid component (D) in the polyamide resin composition according to the first embodiment. Therefore, the description of the olefin copolymer modified by an acid component (D) in the polyamide resin composition according to the first embodiment will be used with reference.

[0112] <(E) Inorganic Filler> The polyamide resin composition according to the second embodiment preferably further contains (E) an inorganic filler. The (E) inorganic filler in the polyamide resin composition according to the second embodiment is the same as the (E) inorganic filler in the polyamide resin composition according to the first embodiment. Therefore, the explanation of the (E) inorganic filler in the polyamide resin composition according to the first embodiment will be used by reference.

[0113] <(F) Other Components> The polyamide resin composition according to the second embodiment preferably further contains (F) other components. The (F) other components in the polyamide resin composition according to the second embodiment are the same as the (F) other components in the polyamide resin composition according to the first embodiment. Therefore, the explanation of the (F) other components in the polyamide resin composition according to the first embodiment will be used by reference.

[0114] [Method for Producing Polyamide Resin Composition] The method for producing the polyamide resin composition according to the first embodiment is not particularly limited, as long as it involves mixing (A) a crystalline semi-aromatic polyamide resin and (B) an aliphatic polyamide resin, and optionally (C) a polyphenylene ether, (D) an olefin copolymer modified with an acid component, (E) an inorganic filler, and (F) other components. The method for producing the polyamide resin composition according to the second embodiment is not particularly limited, as long as it involves mixing (A) a crystalline semi-aromatic polyamide resin, (B) an aliphatic polyamide resin, and (C) a polyphenylene ether, and optionally (D) an olefin copolymer modified with an acid component, (E) an inorganic filler, and (F) other components. As for the method of mixing each of the above components, for example, one method is to mix them using a single-screw or twin-screw extruder and then supply them to a melt kneader for kneading.

[0115] The method for supplying the components constituting the polyamide resin composition to the melt kneader may be to supply all components at once to the same supply port, or to supply each component from different supply ports. The melt kneading temperature is preferably about 10°C to 30°C higher than the melting point of (A) the crystalline semi-aromatic polyamide resin. The shear rate in the kneader is 100 sec. －１ The above is preferable, and the average residence time of the resin composition during kneading is preferably 0.5 minutes or more and 3 minutes or less. The amount of each component used when producing the polyamide resin composition of this embodiment is the same as the amount of each component in the polyamide resin composition described above.

[0116] [Molded Article] The molded article of this embodiment contains the polyamide resin composition of this embodiment described above. The method for obtaining the molded article of this embodiment is not particularly limited, and known molding methods can be used. Examples of known molding methods include extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decorative molding, molding of other materials, gas-assisted injection molding, foam injection molding, low-pressure molding, ultra-thin-wall injection molding (ultra-high-speed injection molding), and in-mold composite molding (insert molding, outsert molding).

[0117] The molded product of this embodiment preferably has a surface roughness of 3 μm to 10 μm. A surface roughness within this range tends to improve paint adhesion and paintability. The surface roughness of the molded product was measured using a KEYENCE one-shot 3D shape measuring machine (VR5000 series).

[0118] The molded products of this embodiment are not limited to the applications of automobile frame parts, racket frame parts, fishing reel parts, robot arms, and electronic device housings.

[0119] The molded article in the preferred embodiment is a molded article of the polyamide resin composition of this embodiment, which is used for a bicycle frame, a racket frame, or a fishing reel. The above molded article has excellent rigidity and mechanical strength after water absorption and a small rate of dimensional change due to water absorption, making it suitable for use in bicycle frame parts, racket frame parts, or fishing reel parts.

[0120] [Method for Painting Molded Articles] The method for painting molded articles according to this embodiment includes a step of applying paint to a molded article containing the polyamide resin composition described above. The method for painting molded articles according to this embodiment is not particularly limited as long as it includes a step of applying paint to a molded article containing the polyamide resin composition described above. A preferred embodiment is one in which the paint is applied by spraying the paint onto the molded article in the paint application step. The paint is not particularly limited, but examples include acrylic paints, urethane paints, silicone paints, and fluorine-based paints. In addition, the paint can be oil-based or water-based. The method for painting molded articles according to this embodiment may include a step of cleaning the molded article before the paint application step.

[0121] [Article] The article of this embodiment includes a molded article containing the polyamide resin composition described above, and a coating film made of paint. The paint used in the article is not particularly limited, but examples include acrylic paints, urethane paints, silicone paints, and fluorine-based paints. The paint can be oil-based or water-based. Specifically, the article of this embodiment includes bicycle frame parts, racket frame parts, and fishing reel parts. The article is obtained by applying paint to a molded article.

[0122] The present invention will be described in detail below with reference to specific examples and comparative examples, but the present invention is not limited to the following examples.

[0123] <Components> The components of the polyamide resin composition used in this example and comparative example are described below.

[0124] ((A) Crystalline semi-aromatic polyamide resin) A-1: ​​Polyamide 4T / 6T copolyamide (indicated as "PA4T / 6T" in the table, synthesized according to Synthesis Example 1 below) A-2: Polyamide 6T / 6I copolyamide (manufactured by Mitsui Chemicals, Arlen A3000) (indicated as "PA6T / 6I" in the table)

[0125] [Synthesis Example 1: Synthesis of (A-1) Polyamide 4T / 6T Copolyamide] Based on the method described in Japanese Patent No. 7043705, (A-1) polyamide 4T / 6T copolyamide was prepared by appropriately adjusting the monomer ratio, reaction time, etc. The proportion of terephthalic acid units in the total dicarboxylic acid units constituting the obtained polyamide 4T / 6T copolyamide was 100 mol%.

[0126] (B) Aliphatic polyamide resins B-1: Polyamide 610 (indicated as "PA610" in the table, synthesized according to Synthesis Example 2 below), melting point = 224°C, glass transition temperature (Tg) = 71°C, C / N = 8 B-2: Polyamide 66 (indicated as "PA66" in the table, synthesized according to Synthesis Example 2 below), melting point = 263°C, glass transition temperature (Tg) = 87°C, C / N = 6 B-3: Polyamide 410 (indicated as "PA410" in the table, synthesized according to Synthesis Example 2 below), melting point = 248°C, glass transition temperature (Tg) = 81°C, C / N = 7 B-4: Polyamide 12 (indicated as "PA12" in the table, manufactured by UBE Corporation, product name "UBESTA"), C / N = 12

[0127] [Synthesis Example 2: Synthesis of Aliphatic Polyamides (PA610, PA66, PA410)] The polymerization reaction of polyamides was carried out by the "thermal fusion polymerization method" as follows. An aqueous solution was prepared by dissolving 1500 g of equimolar salts of the aliphatic diamine compound and the aliphatic dicarboxylic acid compound corresponding to each aliphatic polyamide resin in 1500 g of distilled water. This aqueous solution was placed in an autoclave with an internal volume of 5.4 L and purged with nitrogen. The solution was then gradually concentrated while stirring at a temperature of approximately 110°C to 150°C until the solution concentration reached 70% by mass. The internal temperature was then raised to 220°C and the pressure inside the autoclave was increased to 1.8 MPa. The reaction was allowed to continue for 1 hour, and then the pressure was reduced after 1 hour. The autoclave was then maintained under reduced pressure of 650 torr for 10 minutes using a vacuum device. The mixture was then formed into strands from the bottom spindle, cooled with water, cut, and discharged in pellet form to obtain each (B) aliphatic polyamide.

[0128] ((C) Polyphenylene ether) C-1: Maleic anhydride-modified polyphenylene ether (manufactured by Asahi Kasei, R4919) (indicated as "m-PPE" in the table) C-2: Unmodified polyphenylene ether (2,6-dimethyl-1,4-phenylene ether) (indicated as "unmodified PPE" in the table)

[0129] ((D) Copolymers modified by acid components) D-1: Acid-modified polyolefin resin (manufactured by Mitsui Chemicals, Toughmer MH5020) (indicated as "α-olefin copolymer" in the table) D-2: Acid-modified styrene-ethylenebutylene-styrene copolymer (SEBS) resin (manufactured by Asahi Kasei, ToughTec M1943) (indicated as "m-SEBS" in the table)

[0130] (E) Inorganic filler E-1: Carbon fiber (Teijin Corporation, HTC432)

[0131] <Physical Properties and Evaluation> Various physical properties and moldability were measured and evaluated using the following methods.

[0132] (1) Bending strength and flexural modulus after water absorption For each sample of polyamide resin composition, molded products were manufactured by injection molding, and multipurpose test pieces (Type A) were cut from the molded products to prepare bending test pieces (80 mm × 10 mm × 4 mm strips). The bending strength and flexural modulus were measured in accordance with ASTM D790, using a bending test machine (Toyo Seiki: UTM25) at 23°C and a crosshead speed of 5 mm / min.

[0133] (2) Retention rate of flexural modulus after water absorption Based on the value of flexural modulus measured by the method described in (1) above, the retention rate (%) of flexural modulus was calculated using the following formula: Retention rate of flexural modulus after water absorption (%) = (Flexural modulus of water-absorbing test specimen / Flexural modulus of oven-dried test specimen) × 100 The water absorption of the test specimens was carried out in a high-temperature, high-humidity chamber adjusted to a chamber temperature of 70°C and a chamber humidity of 90%, and the physical properties of the samples were measured using water-absorbing test specimens after being conditioned for 14 days.

[0134] (3) Charpy impact strength (notched) Multipurpose test specimens (Type A) produced by injection molding were machined to create notched test specimens in accordance with ISO 2818. The Charpy impact strength of the obtained notched test specimens was measured in a 23°C environment in accordance with JIS K7111 (JIS ISO 179). A higher value indicated superior impact strength.

[0135] (4) Water absorption dimensional change rate A molded product on a flat plate with dimensions of 90 mm in length, 60 mm in width, and 3 mm in thickness was produced by injection molding, and the water absorption dimensional change rate in the length, width, and thickness directions was measured using the following formula, and the average value of the change rate was taken as the water absorption dimensional change rate of the resin composition shown in each example and comparative example. Water absorption dimensional change rate (length) = [(Ln - L0) / L0] (Ln: length in the length direction after humidity control for n hours (mm) L0: length in the length direction before humidity control (mm)) The dimensional change rate in the width direction and thickness direction was also calculated using the same formula as above.

[0136] (5) Surface roughness (arithmetic mean height Sa of the flat plate surface) A molded product on a flat plate measuring 90 mm in length, 60 mm in width, and 3 mm in thickness was manufactured by injection molding. The surface of the molded product was analyzed using KEYENCE's "VR-5000 analysis application" and "comparative measurement module (VR-H3CA)" to calculate the arithmetic mean height Sa. It is also required that the surface roughness be appropriate and not too rough, so the arithmetic mean height of the flat plate surface was set to 3 μm or more and 10 μm or less.

[0137] (6) Paint Adhesion (Test of Peeling of Paint Film After Painting) After cleaning the surface of the molded product manufactured by injection molding, an oil-based urethane paint was sprayed on, and the presence or absence of peeling between the molded product and the paint film was evaluated. Twenty molded products were painted and evaluated according to the following criteria. (Evaluation Criteria) A: No peeling occurred in any of the samples B: Minor peeling occurred in 1 to 10 samples C: Significant peeling occurred in 1 or more samples, or minor peeling occurred in 10 or more samples

[0138] (7) Melting peak temperature and enthalpy of melting were measured using a differential scanning calorimeter (Diamond-DSC, manufactured by ERKIN-ELMER) in reference to JIS-K 7121. The measurement conditions were as follows: under a nitrogen atmosphere, approximately 10 mg of the polyamide resin composition was heated at a heating rate of 20°C / min to 200°C to 370°C depending on the melting point (Tm) of the sample (during the first heating). The temperature of the melting peak that appeared on the lowest temperature side was defined as the lowest melting peak temperature (Tm-low) (°C), and the temperature of the melting peak that appeared on the highest temperature side was defined as the highest melting peak temperature (Tm-high) (°C). In the table, ΔTm is the difference between the highest melting peak temperature (Tm-high) and the lowest melting peak temperature (Tm-low). Furthermore, the enthalpy of melting for each melting peak was determined from the area of ​​the melting peak.

[0139] <Example 1> Polyamide resin compositions for each example were prepared and evaluated according to the following method.

[0140] (Method for producing polyamide resin composition) Using a twin-screw extruder with 13 barrels, having an upstream feed port on the first barrel from the upstream side and downstream feed ports on the sixth and ninth barrels, (A) crystalline semi-aromatic polyamide resin, (B) aliphatic polyamide resin, and optionally (D) olefin copolymer modified with an acid component were supplied from the upstream feed port. Furthermore, while the resin supplied from the upstream feed port was sufficiently molten, (E) inorganic filler was supplied from the downstream feed port. At this time, (E) inorganic filler could be supplied from either the feed port on the sixth or ninth barrel, and this could be appropriately adjusted depending on the filler used. Furthermore, the twin-screw extruder used in the manufacturing process was equipped with vacuum evaporators in the 5th, 8th, and 12th barrels. When manufacturing the polyamide resin composition of this embodiment using the method described above, the mixture was melted and kneaded under reduced pressure through the vacuum evaporators in the 5th, 8th, and 12th barrels as needed, and the barrel temperature was set to 10°C to 30°C higher than the melting point of (A) crystalline semi-aromatic polyamide resin. Next, the molten mixture extruded from the die head was cooled in strand form and pelletized to obtain pellets of the polyamide resin composition. The types of components used in the production of the polyamide resin composition are as follows, and the amounts of each component are shown in Table 1.

[0141] (Example 1-1) Using a Toshiba Machine Co., Ltd. TEM 35 mm twin-screw extruder (set temperature: 350°C, screw rotation speed: 300 rpm), polyamide was supplied from the top feed port located at the uppermost part of the extruder. In addition, filler was supplied from the side feed port on the downstream side of the extruder (when the resin supplied from the top feed port was sufficiently melted). Next, the molten mixture extruded from the die head was cooled in strand form and pelletized to obtain pellets of the polyamide resin composition. The blending amounts were as shown in Table 1.

[0142] (Examples 1-2 to 1-9, Comparative Examples 1-1 to 1-4) These were manufactured in the same manner as in Example 1-1, except that the compositions were as shown in Table 1.

[0143] Using the polyamide resin compositions obtained in the above examples and comparative examples, molded articles were manufactured by injection molding, and various physical properties were measured and moldability was evaluated. The evaluation results for Examples 1-1 to 1-9 and Comparative Examples 1-1 to 1-4 are shown in Table 1. In Comparative Examples 1-1 and 1-4, only one melting peak was observed.

[0144]

[0145] The results in Table 1 show that the polyamide resin compositions of the examples exhibit excellent bending properties and Charpy impact strength when water is absorbed, and that molded articles obtained from these polyamide resin compositions show small changes in dimensional properties when water is absorbed.

[0146] <Example 2> Polyamide resin compositions for each example were prepared and evaluated according to the following method.

[0147] (Method for producing polyamide resin composition) Using a twin-screw extruder with 13 barrels, having an upstream feed port on the first barrel from the upstream side and downstream feed ports on the sixth and ninth barrels, (A) crystalline semi-aromatic polyamide resin, (B) aliphatic polyamide resin, (C) polyphenylene ether, and optionally (D) olefin copolymer modified with an acid component were supplied from the upstream feed port. Furthermore, while the resin supplied from the upstream feed port was sufficiently molten, (E) inorganic filler was supplied from the downstream feed port. At this time, (E) inorganic filler could be supplied from either the feed port on the sixth or ninth barrel, and this could be appropriately adjusted depending on the filler used. Furthermore, the twin-screw extruder used in the manufacturing process was equipped with vacuum evaporators in the 5th, 8th, and 12th barrels. When manufacturing the polyamide resin composition of this embodiment using the method described above, the mixture was melted and kneaded under reduced pressure through the vacuum evaporators in the 5th, 8th, and 12th barrels as needed, and the barrel temperature was set to 10°C to 30°C higher than the melting point of (A) crystalline semi-aromatic polyamide resin. Next, the molten mixture extruded from the die head was cooled in strand form and pelletized to obtain polyamide composition pellets. The types of components used in the production of the polyamide resin composition are shown in Table 2, and the amounts of each component are shown in Table 2.

[0148] (Example 2-1) Using a Toshiba Machine Co., Ltd. TEM 35 mm twin-screw extruder (set temperature: 350°C, screw rotation speed: 300 rpm), (A) crystalline semi-aromatic polyamide resin, (B) aliphatic polyamide resin, and (C) polyphenylene ether, and (D) an olefin copolymer modified with an acid component were supplied from the top feed port located at the uppermost part of the extruder. In addition, (E) an inorganic filler was supplied from the side feed port on the downstream side of the extruder (when the resin supplied from the top feed port was sufficiently melted). Next, the molten mixture extruded from the die head was cooled in strand form and pelletized to obtain pellets of the polyamide resin composition. The blending amounts are as shown in Table 2.

[0149] (Examples 2-2 to 2-8, Comparative Examples 2-1 to 2-7) These were manufactured in the same manner as in Example 2-1, except that the compositions were as shown in Table 2.

[0150] Using the polyamide resin compositions obtained in the above examples and comparative examples, molded articles were manufactured by injection molding, and various physical properties were measured and evaluated. The evaluation results for Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-7 are shown in Table 2. In Comparative Examples 2-2, 2-3, and 2-5, only one melting peak was observed.

[0151]

[0152] The results in Table 2 show that the polyamide resin compositions of the examples exhibit excellent bending properties and Charpy impact strength when water is absorbed, and that the molded articles obtained from these polyamide resin compositions have a moderately rough surface and excellent paintability.

Claims

1. A polyamide resin composition comprising: (A) a crystalline semi-aromatic polyamide resin; and (B) an aliphatic polyamide resin containing diamine units and dicarboxylic acid units, wherein the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in the repeating units (C / N) is 7.0 or more and 10.0 or less.

2. The polyamide resin composition according to claim 1, wherein the polyamide resin composition has at least two melting peaks in differential scanning calorimetry (DSC), the difference (ΔTm) between the highest melting peak temperature (Tm-high) and the lowest melting peak temperature (Tm-low) among the at least two melting peaks is 90°C or more and 140°C or less, and the ratio [(ΔH-high):(ΔH-low)] of the enthalpy of melting at the highest melting peak temperature (ΔH-high) to the enthalpy of melting at the lowest melting peak temperature (ΔH-low), calculated from the area of ​​the melting peaks, is 5:1 to 2.3:

1.

3. The polyamide resin composition according to claim 2, wherein the highest melting peak temperature (Tm-high) among the at least two melting peaks is 325°C or higher.

4. The polyamide resin composition according to claim 1 or 2, wherein when the total mass of the crystalline semi-aromatic polyamide resin (A) and the aliphatic polyamide resin (B) is 100 parts by mass, the content of the crystalline semi-aromatic polyamide resin (A) is 55 parts by mass or more and 90 parts by mass or less.

5. The polyamide resin composition according to claim 1 or 2, wherein 80 mol% or more of the total dicarboxylic acid units constituting the crystalline semi-aromatic polyamide resin (A) are terephthalic acid units.

6. The polyamide resin composition according to claim 1 or 2, wherein the (A) crystalline semi-aromatic polyamide resin comprises an aliphatic diamine unit having 4 to 6 carbon atoms and a terephthalic acid unit.

7. The polyamide resin composition according to claim 6, wherein the (A) crystalline semi-aromatic polyamide resin comprises tetramethylenediamine units and terephthalic acid units.

8. The polyamide resin composition according to claim 2, wherein the lowest melting peak temperature (Tm-low) is 200°C or higher and 250°C or lower, and the melting enthalpy (ΔH-low) of the melting peak at the lowest melting peak temperature is 5 J / g or higher.

9. The polyamide resin composition according to claim 1 or 2, further comprising (C) polyphenylene ether, wherein the content of (C) polyphenylene ether is 5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the total mass of (A) crystalline semi-aromatic polyamide resin and (B) aliphatic polyamide resin containing diamine units and dicarboxylic acid units.

10. The polyamide resin composition according to claim 9, wherein the polyphenylene ether is a maleic anhydride-modified polyphenylene ether.

11. A polyamide resin composition comprising: (A) a crystalline semi-aromatic polyamide resin; (B) an aliphatic polyamide resin containing diamine units and dicarboxylic acid units, wherein the ratio of the number of carbon atoms (C) to the number of nitrogen atoms (N) in the repeating units (C / N) is 7.0 or more and 10.0 or less; and (C) a polyphenylene ether, wherein when the total mass of the crystalline semi-aromatic polyamide resin (A) and the aliphatic polyamide resin (B) is 100 parts by mass, the content of the crystalline semi-aromatic polyamide resin (A) is 50 parts by mass or more and 90 parts by mass or less; the content of the aliphatic polyamide resin (B) is 10 parts by mass or more and 50 parts by mass or less; and the content of the polyphenylene ether (C) is 5 parts by mass or more and 30 parts by mass or less with respect to the total mass of the crystalline semi-aromatic polyamide resin (A) and the aliphatic polyamide resin (B) of 100 parts by mass.

12. The polyamide resin composition according to claim 11, further comprising (D) an olefin copolymer modified with an acid component, wherein the content of the olefin copolymer modified with the acid component (D) is 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the total mass of the (A) crystalline semi-aromatic polyamide resin and the (B) aliphatic polyamide resin.

13. The polyamide resin composition according to claim 11 or 12, further comprising (E) an inorganic filler, wherein the content of (E) the inorganic filler is 10 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the total mass of (A) the crystalline semi-aromatic polyamide resin and (B) the aliphatic polyamide resin.

14. A molded article comprising the polyamide resin composition described in claim 11 or 12, wherein the surface roughness is 3 μm or more and 10 μm or less.

15. A molded article comprising the polyamide resin composition according to claim 11 or 12, which is used for bicycle frame parts, racket frame parts, or fishing reel parts.

16. An article having a molded article containing the polyamide resin composition according to claim 11 or 12, and a coating film made of a coated paint.

17. A method for painting a molded article, comprising the step of applying a paint to a molded article containing the polyamide resin composition according to claim 11 or 12.

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