JP7682815B2 - Polyamide resin composition - Google Patents

Description

The present invention relates to a polyamide resin composition.

Polyamide resin can achieve high rigidity by blending glass fibers. However, glass fibers have the property of being oriented in the flow direction of the resin, which can cause anisotropy in strength and lead to warping. As a technology for achieving low warping, a technology for blending flat cross-section glass fibers has been proposed (see, for example, Patent Documents 1 and 2). As a technology for achieving high vibration resistance, a glass fiber-reinforced polyamide resin composition has been proposed in which aliphatic polyamide and polymetaxylene adipamide are used in combination with glass fibers having a specific cross-sectional area (see, for example, Patent Document 3).

Japanese Patent Application Publication No. 10-219026 International Publication No. 2008/120703 International Publication No. 2014/171363

However, with conventional techniques, it has sometimes been difficult to achieve a good surface appearance when a molded product is formed while maintaining high rigidity and low warpage.
An object of the present invention is to provide a polyamide resin composition that can achieve high rigidity, low warpage and good surface appearance in a molded article.

Specific means for solving the above problems are as follows.
The polyamide resin composition comprises a polyamide resin (A) and glass fibers (B), the polyamide resin (A) comprises one type of crystalline polyamide resin (A-1) and one type of amorphous polyamide resin (A-2), the glass fibers (B) comprise glass fibers (B-1) having a noncircular cross section, and the total content of the glass fibers (B) is 40% by mass or more and 80% by mass or less.

The present invention provides a polyamide resin composition that can achieve high rigidity, low warpage, and good surface appearance in molded products.

In this specification, the content of each component in a composition means the total amount of the multiple substances present in the composition when multiple substances corresponding to each component are present in the composition, unless otherwise specified.

[Polyamide resin composition]
The polyamide resin composition of the present embodiment includes a polyamide resin (A) and a glass fiber (B), the polyamide resin (A) includes a crystalline polyamide resin (A-1) and an amorphous polyamide resin (A-2) having an MVR of 50 ml/10 min or more measured at 275 ° C. and a load of 5 kg according to ISO1133, the glass fiber (B) includes a noncircular cross section glass fiber (B-1), and the total content of the glass fiber (B) is 40% by mass or more and 80% by mass or less. By blending the crystalline polyamide resin (A-1) and the specific amorphous polyamide resin (A-2) with the noncircular cross section glass fiber (B-1) at a specific content, when a molded article is formed, a good surface appearance can be achieved while maintaining high rigidity and low warpage.

Polyamide resin (A)
The polyamide resin composition contains, as polyamide resins, at least one type of crystalline polyamide resin (A-1) and at least one type of amorphous polyamide resin (A-2) having an MVR of 50 ml/10 min or more measured at a temperature of 275° C. and a load of 5 kg according to ISO 1133. By combining the crystalline polyamide resin (A-1) with the amorphous polyamide resin (A-2) having a specific MVR value, it is possible to realize a good surface appearance in a molded article while maintaining high rigidity and low warpage.

Crystalline polyamide resin (A-1)
In this specification, the crystalline polyamide resin (A-1) means a polyamide resin that shows a clear endothermic peak due to melting in a differential scanning calorimeter (DSC) analysis under a temperature increase condition of 10°C/min, specifically, a polyamide resin having a crystalline melting heat of more than 1 cal/g.

Examples of the crystalline polyamide resin (A-1) include aliphatic polyamide resins made of aliphatic diamines and aliphatic dicarboxylic acids, and aliphatic polyamide resins made of lactams or aminocarboxylic acids. The crystalline polyamide resin (A-1) is preferably an aliphatic polyamide resin.

Examples of monomer components constituting aliphatic polyamide resins include a combination of an aliphatic diamine having 2 to 20 carbon atoms, preferably 4 to 12 carbon atoms, and an aliphatic dicarboxylic acid having 2 to 20 carbon atoms, preferably 6 to 12 carbon atoms, and a lactam or aminocarboxylic acid having 6 to 12 carbon atoms.

Examples of aliphatic diamines include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, and eicosanediamine. Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedionic acid, dodecanedionic acid, tridecanedionic acid, tetradecanedionic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and eicosanedionic acid.

Examples of combinations of aliphatic diamines and aliphatic dicarboxylic acids include a combination of hexamethylenediamine and adipic acid, a combination of hexamethylenediamine and sebacic acid, and a combination of hexamethylenediamine and dodecanedioic acid, and the like. Equimolar salts of these combinations are preferably used.

Examples of lactams include ε-caprolactam, enantholactam, undecane lactam, dodecane lactam, α-pyrrolidone, α-piperidone, etc. Examples of aminocarboxylic acids include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. Among these, from the viewpoint of polymerization production, at least one selected from the group consisting of ε-caprolactam, undecane lactam, and dodecane lactam is preferred.

The monomer components constituting the aliphatic polyamide resin may be one type alone or two or more types in combination. Here, a combination of an aliphatic diamine and an aliphatic dicarboxylic acid is considered to be one type of monomer component, with one type of aliphatic diamine and one type of aliphatic dicarboxylic acid being the combination.

From the viewpoint of productivity, the crystalline polyamide resin (A-1) is preferably selected from the group consisting of polyamide 6, polyamide 66, polyamide 6/66, polyamide 6/12, polyamide 610, polyamide 612, polyamide 6/66/12, polyamide 11, and polyamide 12, and more preferably polyamide 6 and/or polyamide 66.
The crystalline polyamide resin (A-1) may be one type alone or two or more types in combination. When two or more types of crystalline polyamide resins are contained, the total content of the other crystalline polyamide resins relative to the crystalline polyamide resin having the largest content is, for example, 25% by mass or less, and preferably 5% by mass or less.

The relative viscosity of the crystalline polyamide resin (A-1) is not particularly limited, but it is preferable that the relative viscosity of the crystalline polyamide resin (A-1) at a concentration of 1% in 98% sulfuric acid measured at 25°C in accordance with JIS K 6810 is 1.8 or more and 5.0 or less.

From the viewpoints of mechanical properties and surface appearance, the content of the crystalline polyamide resin (A-1) in the total amount of the polyamide resin composition is, for example, preferably 20% by mass or more and less than 60% by mass, and more preferably 30% by mass or more and 50% by mass or less.

Amorphous polyamide resin (A-2)
In this specification, the amorphous polyamide resin (A-2) means a polyamide resin which hardly crystallizes or has a very slow crystallization rate. Specifically, it means a polyamide resin which does not show a clear endothermic peak due to melting in a differential scanning calorimeter (DSC) analysis under a temperature increase condition of 10° C./min, and has a crystal fusion heat of 1 cal/g or less.
The amorphous polyamide resin (A-2) has an MVR of 50 ml/10 min or more, preferably 60 ml/10 min or more, measured at 275° C. and a load of 5 kg according to ISO 1133. If the MVR is less than 50 ml/10 min, it may be difficult to achieve a good surface appearance in the molded article. The upper limit of the MVR is, for example, 200 ml/min, preferably 100 ml/min.
When two or more kinds of amorphous polyamide resins are contained, these are mixed and the MVR of the entire amorphous polyamide resin is measured, and when the MVR measured at a temperature of 275°C and a load of 5 kg according to ISO 1133 is 50 ml/10 min or more, the entire amorphous polyamide resin can be called amorphous polyamide resin (A-2). The MVR is preferably measured as described above, but when the MVR of each amorphous polyamide resin and its mixing ratio are known, the average value calculated by multiplying each MVR by the mixing ratio can be calculated as the MVR of the entire amorphous polyamide resin.

The amorphous polyamide resin (A-2) is preferably a polyamide resin having a structure that inhibits crystallization, such as a polyamide having a functional group such as an aliphatic, alicyclic, or aromatic group having a branched structure in the main chain or side chain. From the viewpoint of inhibiting crystallization, it is more preferable that it is a copolymer. The amorphous polyamide resin (A-2) is preferably a copolymer polyamide resin containing at least two aromatic monomer components, and more preferably has a glass transition temperature of 100°C or higher, determined from the peak temperature of the loss modulus in an oven-dry state obtained by measuring the dynamic viscoelasticity. The polymerization method for the amorphous polyamide may be any known method, and is not particularly limited.

Examples of dicarboxylic acids constituting the amorphous polyamide resin (A-2) include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, dibenzoic acid, 4,4'-oxydibenzoic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, and 4,4'-biphenyldicarboxylic acid; and alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid.

Examples of diamines constituting the amorphous polyamide resin (A-2) include alicyclic diamines such as cyclohexanediamine, methylcyclohexanediamine, and isophoronediamine; and aromatic diamines such as p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, and 4,4'-diaminodiphenylether.

Specific examples of the amorphous polyamide resin (A-2) include polycondensates of isophthalic acid/terephthalic acid/hexamethylenediamine/bis(3-methyl-4-aminocyclohexyl)methane, polycondensates of terephthalic acid/2,2,4-trimethylhexamethylenediamine/2,4,4-trimethylhexamethylenediamine, polycondensates of isophthalic acid/bis(3-methyl-4-aminocyclohexyl)methane/ω-laurolactam, and polycondensates of isophthalic acid/terephthalic acid/hexa Examples of the polycondensate include polycondensates of methylenediamine (polyamide 6T/6I), polycondensates of isophthalic acid/2,2,4-trimethylhexamethylenediamine/2,4,4-trimethylhexamethylenediamine, polycondensates of isophthalic acid/terephthalic acid/2,2,4-trimethylhexamethylenediamine/2,4,4-trimethylhexamethylenediamine, and polycondensates of isophthalic acid/bis(3-methyl-4-aminocyclohexyl)methane/ω-laurolactam. Among these, the amorphous polyamide resin (A-2) is preferable because, for example, copolymers having aromatic rings such as polyamide 6T/6I inhibit the crystallization of crystalline polyamide resins.

Specifically, the amorphous polyamide resin (A-2) is preferably one that is composed of 40 to 95 mol % of terephthalic acid component units, 5 to 60 mol % of isophthalic acid component units, and an aliphatic diamine. Preferred combinations of monomer components constituting the amorphous polyamide resin (A-2) include an equimolar salt of hexamethylenediamine and terephthalic acid, and an equimolar salt of hexamethylenediamine and isophthalic acid.
The amorphous polyamide resin (A-2) is preferably a copolymer containing 60% by mass or more and 99% by mass or less of units derived from a monomer component consisting of an aliphatic diamine, isophthalic acid, and terephthalic acid, and containing 1% by mass or more and 40% by mass or less of units of an aliphatic polyamide component.

The relative viscosity of the amorphous polyamide resin (A-2) is not particularly limited, but the relative viscosity measured at 25°C for amorphous polyamide resin (A-2) at a concentration of 1% in 98% sulfuric acid in accordance with JIS K 6810 is preferably 1.5 to 4.0, more preferably 1.8 to 3.0.

From the viewpoints of mechanical properties and surface appearance, the content of the amorphous polyamide resin (A-2) in the total amount of the polyamide resin composition is preferably 0.5% by mass or more and 30% by mass or less, more preferably 0.5% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 25% by mass or less, more preferably 3% by mass or more and 20% by mass or less, and even more preferably 3% by mass or more and 8% by mass or less. The polyamide resin composition may contain one type of amorphous polyamide resin alone or two or more types in combination.

Glass fiber (B)
The polyamide resin composition contains at least glass fibers (B-1) having a noncircular cross section as the glass fibers (B), and the total content of the glass fibers (B) is 40% by mass or more and 80% by mass or less, whereby a molded article can be provided with a good surface appearance while maintaining high rigidity and low warpage.

Glass fiber with non-circular cross section (B-1)
The glass fiber (B-1) with a noncircular cross section is not particularly limited as long as the cross section is noncircular. The noncircular cross section means that in a cross section perpendicular to the longitudinal direction of the glass fiber, a major axis connecting two points on the periphery of the cross section that are the longest distance apart, and a minor axis connecting two points on the line perpendicular to the major axis that are the longest distance apart between two points that intersect with the periphery of the cross section, and the lengths of the major axis and the minor axis are different. The ratio of the major axis to the minor axis of the glass fiber should be greater than 1, and from the viewpoint of mechanical properties, it is, for example, 1.2 or more and 10 or less, preferably 1.5 or more and 6 or less, and more preferably 1.7 or more and 4.5 or less.

The cross-sectional shape of the non-circular cross-section glass fiber (B-1) is usually cocoon-shaped, elliptical, semicircular, arc-shaped, rectangular, parallelogram, or similar shapes. From the viewpoints of fluidity, mechanical properties, and low warpage, cocoon-shaped, elliptical, or rectangular shapes are practically preferred. For specific examples of the cross-sectional shape of the non-circular cross-section glass fiber (B-1), see, for example, JP-A-62-268612.

The thickness of the noncircular cross section glass fiber (B-1) is not particularly limited. The minor axis of the noncircular cross section glass fiber (B-1) is usually 0.5 μm or more and 25 μm or less, and the major axis is 1.25 μm or more and 300 μm or less.
The glass fiber (B-1) having a non-circular cross section generally has a fiber length of 1 mm or more and 15 mm or less, preferably 1.5 mm or more and 12 mm or less, and more preferably 2 mm or more and 6 mm or less.
The aspect ratio, obtained by dividing the fiber length by the average value of the major axis and minor axis of the glass fiber (B-1) having a noncircular cross section, is usually 10 or more, and from the viewpoints of rigidity, mechanical strength, and fluidity, it is preferably 15 to 100.

Examples of the glass constituting the non-circular cross-section glass fiber (B-1) include those composed of A-glass, C-glass, E-glass, etc., and from the viewpoint of the thermal stability of the polyamide resin, E-glass is preferred. The non-circular cross-section glass fiber (B-1) may be surface-treated with a silane coupling agent, a titanium coupling agent, or other polymeric or low molecular surface treatment agent. By being surface-treated, the dispersibility and adhesion in the polyamide resin are improved. The non-circular cross-section glass fiber (B-1) is preferably bound with a binding material from the viewpoint of improving the adhesion with the resin. The binding material is not particularly limited, and from the viewpoint of compatibility with the polyamide resin, it is preferably a urethane resin and/or an acrylic resin.

From the viewpoints of high rigidity, low warpage, and good surface appearance, the content of the noncircular cross-section glass fiber (B-1) in the total amount of the polyamide resin composition is preferably 15% by mass or more and 70% by mass or less, and more preferably 20% by mass or more and 65% by mass or less.

Circular cross-section glass fiber (B-2)
The polyamide resin composition may further contain a circular cross-section glass fiber (B-2) as a glass fiber in addition to the non-circular cross-section glass fiber (B-1). The circular cross-section glass fiber (B-2) is a glass fiber having a circular cross section perpendicular to the longitudinal direction of the glass fiber. The average fiber diameter of the circular cross-section glass fiber (B-2) is, for example, 4 μm or more and 15 μm or less, and more preferably 6 μm or more and 13 μm or less. When the average fiber diameter is within the above range, the mechanical properties and dimensional stability of the molded article tend to be further improved. The average fiber diameter of the circular cross-section glass fiber (B-2) can be measured in accordance with JIS R3420.

The glass fiber (B-2) having a circular cross section usually has a fiber length of 1 mm or more and 15 mm or less, preferably 1.5 mm or more and 12 mm or less, and more preferably 2 mm or more and 6 mm or less.
The aspect ratio, obtained by dividing the fiber length by the average fiber diameter of a glass fiber having a circular cross section, is usually 10 or more, and from the viewpoints of rigidity, mechanical strength, and flowability, is preferably 15 or more and 100 or less.

Glass constituting the circular cross-section glass fiber includes those composed of A glass, C glass, E glass, etc., and E glass is preferred from the viewpoint of thermal stability of polyamide resin. The circular cross-section glass fiber may be surface-treated with a silane coupling agent, a titanium coupling agent, or other polymeric or low molecular surface treatment agent. By being surface-treated, the dispersibility and adhesion in polyamide resin are improved. The circular cross-section glass fiber is preferably bound with a binding material from the viewpoint of improving adhesion with resin. The binding material is not particularly limited, and is preferably a urethane resin and/or an acrylic resin from the viewpoint of compatibility with polyamide resin.

When the polyamide resin composition contains the glass fiber (B-2) having a circular cross section, the content of the glass fiber (B-2) having a circular cross section in the total amount of the polyamide resin composition is preferably 5% by mass or more and less than 40% by mass, and from the viewpoints of high rigidity, low warpage property and good surface appearance, more preferably 10% by mass or more and 35% by mass or less.
The content ratio (B-2/B-1) of the glass fiber having a circular cross section (B-2) to the glass fiber having a noncircular cross section (B-1) is preferably 0.1 or more and 1.2 or less, more preferably 0.3 or more and 1.0 or less, from the viewpoints of high rigidity, low warpage and good surface appearance.

The polyamide resin composition may contain other components, such as plasticizers, impact resistant materials, heat resistant materials, foaming agents, weathering agents, crystal nucleating agents, crystallization accelerators, release agents, lubricants, antistatic agents, flame retardants, flame retardant assistants, pigments, dyes, and other functionality imparting agents, as appropriate, within the scope of the invention.

The polyamide resin composition is produced by melt-kneading a crystalline polyamide resin (A-1), an amorphous polyamide resin (A-2), and a predetermined amount of glass fibers having a noncircular cross section (B-1) in a single-screw or twin-screw extruder, a Banbury mixer, or the like.
The resulting polyamide resin composition can be molded into a desired molded article by a molding method such as extrusion molding, blow molding, or injection molding.

Since molded articles containing the polyamide resin composition of this embodiment have good surface appearance, they are suitable for use in a variety of applications, such as automobile parts, items that require design, and housings. In addition, the gloss (gloss value) of molded articles obtained by injection molding the polyamide resin composition, as measured in accordance with ASTM D-523, is preferably 65% or more, and more preferably 70% or more.

The polyamide resin composition of the present embodiment provides a molded article with high rigidity, low warpage, and good surface appearance.
(Mechanical properties)
In a molded article containing the polyamide resin composition of the present embodiment, the tensile strength measured at 23° C. in accordance with ISO 527-1, 2 is preferably 265 MPa or more.
In a molded article containing the polyamide resin composition of the present embodiment, the tensile modulus measured at 23° C. in accordance with ISO 527-1, 2 is preferably 20 GPa or more.
In a molded article containing the polyamide resin composition of this embodiment, the Charpy impact strength measured at 23°C in accordance with ISO179-1 is preferably 20 kJ/ ^m2 .
The tensile strength and tensile modulus can be measured by the following method. ISO standard TYPE-A test pieces are prepared by injection molding and used to obtain data on mechanical properties. The tensile strength and tensile modulus are measured at 23°C using an Instron tensile tester model 5567 in accordance with ISO 527-1 and 2.
The Charpy impact strength can be measured by the following method. In accordance with ISO179-1, an edgewise impact test is performed at 23°C using a Charpy impact tester No. 258-PC manufactured by Yasuda Seiki Co., Ltd., using a test piece with an A notch and a thickness of 4 mm (n=10).

(Liquidity)
In a molded article containing the polyamide resin composition of the present embodiment, the flow length measured under the following conditions is preferably 85 mm or more.
The flow length is measured from a molded product obtained using a spiral flow type flowability evaluation mold with a cavity size of width w = 15 mm and thickness t = 1 mm, using PS-40E (screw diameter 26 mm, mold clamping force 40 tons) manufactured by Nissei Plastic Industrial Co., Ltd. The molding conditions are a molding temperature of 290°C, a mold temperature of 80°C, and an injection pressure of 100 MPa.

(Surface appearance (glossiness) (gloss))
In a molded article containing the polyamide resin composition of the present embodiment, the gloss (gloss value) measured under the following conditions is preferably 65% or more, and more preferably 70% or more.
A flat plate of 100 mm x 70 mm x 2 mm thickness is prepared using SE100D-C160S (screw diameter 28 mm, mold clamping force 100 tons) manufactured by Sumitomo Heavy Industries, Ltd. The molding conditions are molding temperature 290°C, mold temperature 80°C, injection speed 80 mm/sec, and cooling time 15 seconds. The gloss (gloss value) of the obtained test piece is measured at an incidence angle of 60° using a color computer SM-5-IS-2B manufactured by Suga Test Instruments Co., Ltd. in accordance with ASTM D-523.

(Warpage)
In a molded article containing the polyamide resin composition of the present embodiment, the low warpage property can be evaluated by the following method.
An ISO294-3 D-1 type mold 60 mm x 60 mm x thickness 1 t is prepared using SE100D-C160S (screw diameter 28 mm, mold clamping force 100 ton) manufactured by Sumitomo Heavy Industries, Ltd. The molding conditions are molding temperature 290°C, mold temperature 80°C, injection speed 97 mm/sec, injection pressure 60 MPa, and cooling time 15 seconds. The gate is cut immediately after molding, and the mold is left in a moisture-proof container for 48 hours. A weight is placed on a specified corner on the platen, and the maximum gap with the platen is taken as the amount of warpage deformation. If the obtained deformation amount is 3 mm or more, it is considered that there is warpage deformation, and if it is less than 3 mm, it is considered that there is no warpage deformation.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The methods for evaluating the physical properties of the resins and molded products used in the examples and comparative examples are shown below.

[Mechanical properties]
ISO standard TYPE-A test pieces were prepared by injection molding and used to obtain data on mechanical properties. The tensile strength and tensile modulus were measured at 23°C using an Instron tensile tester, model 5567, in accordance with ISO 527-1 and 2.

[Charpy impact strength]
In accordance with ISO179-1, an edgewise impact test was performed at 23°C using a Charpy impact tester No. 258-PC manufactured by Yasuda Seiki Co., Ltd., using a test piece having an A notch and a thickness of 4 mm (n=10).

[Liquidity]
The flow length was measured from a molded product obtained using a spiral flow type flowability evaluation mold with a cavity size of width w = 15 mm and thickness t = 1 mm, using PS-40E (screw diameter 26 mm, mold clamping force 40 tons) manufactured by Nissei Plastic Industrial Co., Ltd. The molding conditions were a molding temperature of 290°C, a mold temperature of 80°C, and an injection pressure of 100 MPa.

[Glossiness (Gloss)]
A flat plate of 100 mm x 70 mm x 2 mm thickness was prepared using SE100D-C160S (screw diameter 28 mm, mold clamping force 100 tons) manufactured by Sumitomo Heavy Industries, Ltd. The molding conditions were molding temperature 290°C, mold temperature 80°C, injection speed 80 mm/sec, and cooling time 15 seconds. The gloss (gloss value) of the obtained test piece was measured at an incidence angle of 60° using a color computer SM-5-IS-2B manufactured by Suga Test Instruments Co., Ltd. in accordance with ASTM D-523.

[Warpage deformation]
Using SE100D-C160S (screw diameter 28 mm, mold clamping force 100 ton) manufactured by Sumitomo Heavy Industries, Ltd., a D-1 type mold 60 mm x 60 mm x thickness 1 t of ISO294-3 was prepared. The molding conditions were molding temperature 290°C, mold temperature 80°C, injection speed 97 mm/sec, injection pressure 60 MPa, and cooling time 15 seconds. The gate was cut immediately after molding, and the mold was left in a moisture-proof container for 48 hours, after which a weight was placed on a specified corner on the platen, and the maximum gap between the platen and the weight was taken as the amount of warpage deformation. When the obtained deformation amount was 3 mm or more, it was determined that there was warpage deformation, and when it was less than 3 mm, it was determined that there was no warpage deformation.

Polyamide resin (A)
Crystalline polyamide resin (A-1)
PA6-1: A polyamide 6 resin having a relative viscosity of 2.43 to 2.51 measured at 25°C in 96% sulfuric acid at a concentration of 1% in accordance with JIS K 6810, and made of caprolactam having 6 carbon atoms.
PA6-2: A polyamide 6 resin made of caprolactam having 6 carbon atoms, having a relative viscosity of 2.16 to 2.25 as measured at 25°C for a crystalline polyamide resin at a concentration of 1% in 96% sulfuric acid in accordance with JIS K 6810.
Amorphous polyamide resin (A-2) having an MVR of 50 ml/10 min or more measured at 275° C. and a load of 5 kg according to ISO 1133
PA6T/6I-1: Grivory G16 (manufactured by EMS-CHEMIE (Japan)) having an MVR of 100 ml/10 min measured at a temperature of 275° C. and a load of 5 kg according to ISO 1133
PA6T/6I-2: Grivory G21 (manufactured by EMS-CHEMIE (Japan)) having an MVR of 25 ml/10 min measured at a temperature of 275° C. and a load of 5 kg according to ISO 1133

・Glass fiber GF1: Glass fiber with a non-circular cross section (manufactured by Nitto Boseki Co., Ltd., CSG3PA-820S)
Ratio of major axis to minor axis: 4, fiber diameter: 7 x 28 μm
GF2: Glass fiber with a circular cross section (CS 3DE-456S, manufactured by Nitto Boseki Co., Ltd.)
Average fiber diameter: 6 μm
GF3: Glass fiber with a circular cross section (manufactured by Nippon Electric Glass Co., Ltd., ECS 03T-249)
Average fiber diameter: 13 μm

・PA6 Black MB
A black master batch containing dye and pigment components in a polyamide 6 base (UBE NYLON 1013MBC manufactured by Ube Industries, Ltd.)

・Molding aid-2
Pentalyt (manufactured by Koei Chemical Industry Co., Ltd.)
・Molding aid-2
LICOWAX OP POWDER (Clariant Japan Co., Ltd.)

Heat-resistant agent CuI, KI mixture (weight ratio 1:6)
CuI Cuprous iodide F (manufactured by Ise Chemical Industries Co., Ltd.)
KI Powdered potassium iodide (Mitsui Fine Co., Ltd.)

Examples 1 to 9, Comparative Examples 1 to 8
The polyamide resin and glass fiber shown in Table 1 were melt-kneaded in a TEX44HCT twin-screw kneader to prepare pellets of the desired polyamide resin composition.
Next, various test pieces were produced using the obtained pellets, and various physical properties were evaluated. The obtained results are shown in Table 1. In Table 1, "-" means that no compound was added.

As is clear from the results in Table 1, when a molded article is formed using the polyamide resin composition of the present invention, it is possible to achieve high rigidity, low warpage, and good surface appearance.

The disclosure of Japanese Patent Application No. 2016-018653 (filing date: February 3, 2016) is incorporated herein by reference in its entirety.
All publications, patent applications, and standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or standard was specifically and individually indicated to be incorporated by reference.

Claims (7)

Contains a polyamide resin (A) and glass fibers (B),
The polyamide resin (A) comprises a crystalline polyamide resin (A-1) and an amorphous polyamide resin (A-2) having an MVR of 50 ml/10 min or more and 200 ml/min or less , as measured at a temperature of 275° C. and a load of 5 kg according to ISO 1133;
The glass fiber (B) includes a glass fiber (B-1) having a noncircular cross section and a glass fiber (B-2) having a circular cross section,
The total content of the glass fibers (B) is 40% by mass or more and 80% by mass or less based on the total amount of the polyamide resin composition,
the content ratio (B-2/B-1) of the glass fiber having a circular cross section (B-2) to the glass fiber having a noncircular cross section (B-1) is 0.3 or more and 1.0 or less ;
the content of the amorphous polyamide resin (A-2) is 0.5% by mass or more and 8% by mass or less based on the total amount of the polyamide resin composition;
The polyamide resin composition , wherein the amorphous polyamide resin (A-2) contains polyamide 6T/6I . The polyamide resin composition according to claim 1, wherein the ratio of the major axis to the minor axis in the cross section perpendicular to the longitudinal direction of the noncircular cross-section glass fiber (B-1) is 1.2 or more and 10 or less. The polyamide resin composition according to claim 1 or 2, wherein the average fiber diameter of the glass fiber (B-2) having a circular cross section is 4 μm or more and 15 μm or less. The polyamide resin composition according to any one of claims 1 to 3 , wherein the crystalline polyamide resin (A-1) is selected from the group consisting of polyamide 6, polyamide 66, polyamide 6/66, polyamide 6/12, polyamide 610, polyamide 612, polyamide 6/66/12, polyamide 11 and polyamide 12. The polyamide resin composition according to any one of claims 1 to 4, wherein the crystalline polyamide resin (A-1) contains polyamide 6. The polyamide resin composition according to any one of claims 1 to 5 , wherein the content of the non-circular cross-sectional glass fiber (B-1) is 5% by mass or more and 70% by mass or less based on the total amount of the polyamide resin composition. A molded article comprising the polyamide resin composition according to any one of claims 1 to 6 .