JP7514449B2 - Carbon fiber reinforced polyamide resin composition and molded article thereof - Google Patents

Description

The present invention relates to a light and strong carbon fiber reinforced polyamide resin composition obtained by adding carbon fiber to a specific polyamide resin with a high melting point and low water absorption. In particular, the present invention relates to a polyamide resin composition that has a very low water absorption rate, a small decrease in glass transition temperature upon water absorption, and a molded product that does not lose strength even when it absorbs water, and has excellent appearance and toughness. The polyamide resin composition of the present invention can be suitably used for parts that have traditionally been made of metal, such as housings for electronic and electrical parts, vehicle parts used in the interior and exterior of automobiles, and sports and leisure parts.

Polyamide resin can exhibit high strength, rigidity, and high load deflection by kneading and reinforcing carbon fiber in an extruder. Therefore, carbon fiber reinforced polyamide resin compositions are widely used as internal and external components in the fields of electronic and electrical equipment, automobiles, motorcycles, bicycles, and other vehicles. In recent years, there has been an increasing demand for lighter and stronger products, particularly in terms of thinner product thickness in electronic and electrical components, and lighter weight due to smaller sizes and replacement of metals in vehicle parts, and thermoplastic resin compositions with higher specific strength, expressed as strength/specific gravity, are in demand. However, polyamide resin compositions generally have a high water absorption rate, which causes a decrease in strength and elasticity when they absorb water, so glass fiber reinforced polyamide resin compositions based on polyamide 6 and polyamide 66 components, for example, have the disadvantage that their strength decreases when they absorb water. In addition, some polyamides have a low water absorption rate, but when the amount of carbon fiber added is large, the fibers are severely broken and shortened during melt mixing, and the strength is insufficient despite the high specific gravity (density). In addition, the appearance of the molded product is also worse than the amount of carbon fiber added, resulting in poor quality. In addition, many polyamides have a low water absorption rate, but the glass transition temperature drops significantly when they absorb water, causing a decrease in strength and elastic modulus. Therefore, their use is limited in electronic and electrical parts housings, vehicle parts used in the interior and exterior of automobiles, and sports and leisure parts.

In recent years, especially in the mounting of electrical and electronic components, surface mounting methods (flow and reflow methods) have rapidly spread due to the miniaturization of components, high density mounting, simplified processes, and reduced costs associated with the miniaturization of product sizes. In surface mounting methods, the process atmosphere temperature is higher than the solder melting temperature (240 to 260°C), so the resin used is inevitably required to be heat resistant at the above atmosphere temperature. In addition, in the surface mounting process, swelling and deformation of the mounted components due to the resin's water absorption can be a problem, so the resin used is required to have low water absorption. Resins that satisfy these characteristics include 6T polyamide and 9T polyamide, and for example, Patent Document 1 and Patent Document 2 indicate that these aromatic polyamides can be used for surface-mounted electrical and electronic components.

Patent Document 3 proposes a method of adding specific carbon fibers to polyamide 6 for the purpose of reducing weight and increasing rigidity. However, polyamide 6 has a problem in that its elastic modulus and strength decrease significantly when it absorbs water.

Patent Document 4 proposes a carbon fiber reinforced polyamide resin composition that is excellent in mechanical properties and appearance by using a specific polyamide resin and a specific carbon fiber. However, the strength exhibited is low compared to the amount of carbon fiber added, and it cannot be said that a sufficiently light and strong carbon fiber reinforced polyamide resin composition has been proposed.

Patent Document 5 proposes a carbon fiber reinforced polyamide resin composition with excellent mechanical properties and appearance by combining a specific polyamide resin with a specific carbon fiber in a relatively small specific amount. However, it has not been possible to propose a highly loaded carbon fiber reinforced polyamide resin composition that is free of poorly dispersed and agglomerated foreign matter, is sufficiently strong and light, and has high physical properties even after absorbing water.

Japanese Patent Application Laid-Open No. 3-88846 Japanese Patent No. 3474246 JP 2006-1964 A JP 2012-255063 A Japanese Patent No. 6210217

When preparing a carbon fiber reinforced polyamide resin composition, it is more difficult to disperse and defibrate carbon fibers uniformly and to ensure a stable dispersion state than glass fibers, and the poor fiber dispersion makes it difficult to obtain a good surface condition of the molded product. In addition, if the kneading is intensified too much to obtain a good surface condition of the molded product, the fibers are broken and shortened, and sufficient strength cannot be obtained. Therefore, it is an important issue to achieve both uniform dispersion of carbon fibers and strength. The present invention was devised in consideration of the current state of the prior art described above, and the object of the present invention is to provide a polyamide resin composition with a high carbon fiber loading that is free of poorly dispersed and agglomerated foreign matter, is sufficiently strong and light, has little deterioration in physical properties when absorbing water, has a good appearance of the molded product, and is free of poorly dispersed and agglomerated foreign matter.

As a result of extensive research into achieving this objective, the inventors have used a specific crystalline polyamide resin and an amorphous polyamide resin from among various polyamide resins, and by adding a certain amount of carbon fiber and melt-kneading it by side-feeding it from the upstream side, have obtained a carbon fiber-reinforced polyamide resin composition which has a good appearance when molded, is sufficiently strong and light, and has high physical properties even after absorbing water.

That is, the present invention employs the following configurations (1) to (6).
(1) A carbon fiber reinforced polyamide resin composition containing 50 to 90 parts by mass of a polyamide resin (A) and 10 to 50 parts by mass of carbon fiber (B), wherein the polyamide resin (A) contains 70 to 99% by mass of a semi-aromatic crystalline polyamide resin (A1) having terephthalic acid as a constituent component and 1 to 30% by mass of an amorphous polyamide resin (A2), and the number of poorly dispersed and agglomerated foreign matter in a flat test piece having a length of 100 mm, a width of 100 mm and a thickness of 1 mm obtained by injection molding the carbon fiber reinforced polyamide resin composition is 15 or less.
(2) The carbon fiber reinforced polyamide resin composition according to (1), wherein the terminal carboxyl group concentration (CEG) of the semi-aromatic crystalline polyamide resin (A1) containing terephthalic acid as a constituent component is 40 eq/ton or more.
(3) The carbon fiber reinforced polyamide resin composition according to (1) or (2), further comprising 0.01 to 2.0 parts by mass of an antioxidant (C) per 100 parts by mass of the total of the polyamide resin (A) and the carbon fiber (B).
(4) The carbon fiber reinforced polyamide resin composition according to any one of (1) to (3), further comprising 0.01 to 0.5 parts by mass of a copper compound (D) per 100 parts by mass of the total of the polyamide resin (A) and the carbon fiber (B).
(5) A molded article made of the carbon fiber reinforced polyamide resin composition according to any one of (1) to (4).

The carbon fiber reinforced polyamide resin composition of the present invention is a carbon fiber reinforced polyamide resin composition in which the type and amount of polyamide resin and carbon fiber are specified to specific types and amounts, and when a certain amount of carbon fiber is added and melt-kneaded, it is side-fed from the upstream side of the standard supply position of fiber-based reinforcing materials such as glass fiber, resulting in a carbon fiber reinforced polyamide resin composition with good molded product appearance, strength and lightness, extremely low water absorption, and extremely little strength loss due to water absorption. It is extremely useful as housings for electronic and electrical parts, vehicle parts used in the interior and exterior of automobiles, and sports and leisure parts.

The carbon fiber reinforced polyamide resin composition of the present invention contains polyamide resin (A) and carbon fiber (B). The content (mixture amount) of each component in the carbon fiber reinforced polyamide resin composition is expressed as the amount when the total of polyamide resin (A) and carbon fiber (B) is 100 parts by mass, unless otherwise specified. Polyamide resin (A) contains semi-aromatic crystalline polyamide resin (A1) and amorphous polyamide resin (A2) containing terephthalic acid as a constituent component, and the content ratio (mixture ratio) of (A1) and (A2) is expressed as the ratio (mass%) when polyamide resin (A) is 100% by mass, unless otherwise specified. In the present invention, the amorphous polyamide resin is a polyamide resin that does not show a clear melting point peak when the polyamide resin is measured by DSC at a heating rate of 20 ° C / min in accordance with JIS K 7121: 2012. Conversely, a crystalline polyamide resin is one that shows a clear melting point peak. In the present invention, the blending amount (blending ratio) of each component directly corresponds to the content (content ratio) in the carbon fiber reinforced polyamide resin composition.

The carbon fiber reinforced polyamide resin composition of the present invention contains 50 to 90 parts by mass of polyamide resin (A). The content of polyamide resin (A) is preferably 55 to 85 parts by mass. The content of polyamide resin (A) in the above range is preferable because it allows the molded product to exhibit high strength and excellent appearance, and also reduces the number of poorly dispersed and agglomerated foreign matter.

The semi-aromatic crystalline polyamide resin (A1) used in the present invention is not particularly limited except that it contains terephthalic acid as a constituent component, and is a semi-aromatic polyamide having an acid amide bond (—CONH—) in the molecule.
Examples of the semi-aromatic crystalline polyamide resin (A1) containing terephthalic acid as a constituent component (hereinafter, may be simply referred to as semi-aromatic crystalline polyamide resin (A1)) include 6T-based polyamides (for example, polyamide 6T6I consisting of terephthalic acid/isophthalic acid/hexamethylenediamine, polyamide 6T66 consisting of terephthalic acid/adipic acid/hexamethylenediamine, polyamide 6T6I66 consisting of terephthalic acid/isophthalic acid/adipic acid/hexamethylenediamine, polyamide 6T6I66 consisting of terephthalic acid/hexamethylenediamine/2-methyl-1, Examples of the polyamides include polyamide 6T/M-5T made of 5-pentamethylenediamine, polyamide 6T6 made of terephthalic acid/hexamethylenediamine/ε-caprolactam, polyamide 6T/4T made of terephthalic acid/hexamethylenediamine/tetramethylenediamine), 9T polyamides (terephthalic acid/1,9-nonanediamine/2-methyl-1,8-octanediamine), 10T polyamides (terephthalic acid/1,10-decanediamine), and 12T polyamides (terephthalic acid/1,12-dodecanediamine).

The semi-aromatic crystalline polyamide resin (A1) used in the present invention preferably has a terminal carboxyl group concentration (CEG) of 20 eq/ton or more. In order to significantly express the effects of the present invention, the CEG is more preferably 40 eq/ton or more, even more preferably 50 eq/ton or more, and particularly preferably 60 eq/ton or more. If the CEG is below the above lower limit, the compatibility with the carbon fiber decreases, and there is a tendency for the strength to decrease and the dispersion of the carbon fiber to be poor. Although there are no particular limitations on the upper limit of CEG, from the viewpoint of manufacturing stability, it is preferably 200 eq/ton or less, more preferably 190 eq/ton or less, and even more preferably 180 eq/ton or less.

The semi-aromatic crystalline polyamide resin (A1) used in the present invention preferably has a DSC melting peak temperature (Tm) at the lowest temperature side measured by the method described in the Examples section below of 280°C or higher. It is more preferably 290°C or higher, and even more preferably 300°C or higher. If Tm is below the above lower limit, when the molded body of the present invention is processed in a solder reflow process, the molded body may melt or deform. The upper limit of Tm is preferably 340°C or lower, more preferably 330°C or lower, and even more preferably 320°C or lower. If Tm exceeds the above upper limit, the processing temperature during molding becomes extremely high, and decomposition of the resin due to heat may occur.

From the viewpoints of melting point (Tm) and glass transition temperature (Tg), the semi-aromatic crystalline polyamide resin (A1) used in the present invention is preferably the following semi-aromatic polyamide resin.
The semi-aromatic crystalline polyamide resin (A1) is preferably a semi-aromatic polyamide resin containing 50 to 100 mol% of repeating units consisting of a diamine having 6 to 12 carbon atoms and terephthalic acid, and 0 to 50 mol% of repeating units consisting of an aminocarboxylic acid or lactam having 10 or more carbon atoms, more preferably a semi-aromatic polyamide resin containing 50 to 98 mol% of repeating units consisting of a diamine having 6 to 12 carbon atoms and terephthalic acid, and 2 to 50 mol% of repeating units consisting of an aminocarboxylic acid or lactam having 10 or more carbon atoms, and even more preferably a semi-aromatic polyamide resin containing 55 to 98 mol% of repeating units consisting of a diamine having 6 to 12 carbon atoms and terephthalic acid, and 2 to 45 mol% of repeating units consisting of an aminocarboxylic acid or lactam having 10 or more carbon atoms.
If the ratio of the repeating units consisting of a diamine having 6 to 12 carbon atoms and terephthalic acid in the semi-aromatic crystalline polyamide resin (A1) is less than 50 mol%, problems may occur due to a decrease in moldability associated with a decrease in crystallinity, melting or deformation of the molded product in a solder reflow process due to a decrease in Tm, and softening of the molded product in the usage environment due to a decrease in Tg. On the other hand, by setting the ratio of the repeating units consisting of a diamine having 6 to 12 carbon atoms and terephthalic acid in the semi-aromatic crystalline polyamide resin (A1) to 55 mol% or more, Tm and Tg can be appropriately improved, which is more preferable.

Examples of diamine components having 6 to 12 carbon atoms that constitute the semi-aromatic polyamide resin (A1) include 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 2-methyl-1,8-octamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, and 1,12-dodecamethylenediamine. These may be used alone or in combination.

As the aminocarboxylic acid having 10 or more carbon atoms or the lactam having 10 or more carbon atoms constituting the semi-aromatic crystalline polyamide resin (A1), an aminocarboxylic acid or lactam having 11 to 18 carbon atoms is preferred. Among these, 11-aminoundecanoic acid, undecane lactam, 12-aminododecanoic acid, and 12-lauryllactam are preferred.

The semi-aromatic crystalline polyamide resin (A1) used in the present invention can be copolymerized with other components in a molar ratio of 50% or less in the structural units. Examples of copolymerizable diamine components include aliphatic diamines such as 1,13-tridecamethylenediamine, 1,16-hexadecamethylenediamine, 1,18-octadecamethylenediamine, and 2,2,4 (or 2,4,4)-trimethylhexamethylenediamine, alicyclic diamines such as piperazine, cyclohexanediamine, bis(3-methyl-4-aminohexyl)methane, bis-(4,4'-aminocyclohexyl)methane, 1,3-bisaminomethylcyclohexane, and isophoronediamine, and aromatic diamines such as metaxylylenediamine, paraxylylenediamine, paraphenylene diamine, and metaphenylene diamine, and hydrogenated versions of these.

Examples of the copolymerizable acid component include aromatic dicarboxylic acids such as isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodium sulfonate isophthalic acid, and 5-hydroxyisophthalic acid; and aliphatic or alicyclic dicarboxylic acids such as fumaric acid, maleic acid, succinic acid, itaconic acid, adipic acid, azelaic acid, sebacic acid, 1,11-undecanedioic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, 1,18-octadecanedioic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, and dimer acid.
Furthermore, examples of copolymerizable components include ε-caprolactam.

Among the above components, from the viewpoint of Tm and Tg, it is preferable that one or more of aminocarboxylic acids having 11 to 18 carbon atoms or lactams having 11 to 18 carbon atoms are copolymerized as the copolymerization components.

The semi-aromatic crystalline polyamide resin (A1) used in the present invention is preferably a semi-aromatic polyamide resin containing 50 to 100 mol % of repeating units consisting of hexamethylenediamine and terephthalic acid and 0 to 50 mol % of repeating units consisting of aminoundecanoic acid or undecane lactam, and more preferably a semi-aromatic polyamide resin containing 50 to 98 mol % of repeating units consisting of hexamethylenediamine and terephthalic acid and 2 to 50 mol % of repeating units consisting of aminoundecanoic acid or undecane lactam. More preferably, it is a semi-aromatic polyamide resin containing 55 to 80 mol % of repeating units composed of hexamethylenediamine and terephthalic acid and 20 to 45 mol % of repeating units composed of aminoundecanoic acid or undecane lactam, and particularly preferably, it is a semi-aromatic polyamide resin containing 60 to 70 mol % of repeating units composed of hexamethylenediamine and terephthalic acid and 30 to 40 mol % of repeating units composed of aminoundecanoic acid or undecane lactam.
If the ratio of the repeating unit consisting of hexamethylenediamine and terephthalic acid in the semi-aromatic crystalline polyamide resin (A1) is less than 50 mol%, problems may occur due to a decrease in moldability associated with a decrease in crystallinity, melting or deformation of the molded body in the solder reflow process due to a decrease in Tm, and softening of the molded body in the usage environment due to a decrease in Tg. On the other hand, by setting the ratio of the repeating unit consisting of hexamethylenediamine and terephthalic acid in the semi-aromatic crystalline polyamide resin (A1) to 55 to 80 mol%, it is possible to control the crystallinity and molecular mobility of the semi-aromatic crystalline polyamide resin (A1), and it is more preferable because it is possible to moderately improve Tm and Tg. Furthermore, by setting the ratio of repeating units consisting of hexamethylenediamine and terephthalic acid in the semi-aromatic crystalline polyamide resin (A1) to 60 to 70 mol %, it is possible to set Tm to 300°C to 320°C and Tg to 70 to 100°C, which not only facilitates molding processing but also leads to stability of the molded product in the solder reflow process and in the usage environment, which is further preferable.

Catalysts used in producing the semi-aromatic crystalline polyamide resin (A1) include phosphoric acid, phosphorous acid, hypophosphorous acid, or their metal salts, ammonium salts, and esters. Specific examples of metal species of metal salts include potassium, sodium, magnesium, vanadium, calcium, zinc, cobalt, manganese, tin, tungsten, germanium, titanium, and antimony. Examples of esters include ethyl ester, isopropyl ester, butyl ester, hexyl ester, isodecyl ester, octadecyl ester, decyl ester, stearyl ester, and phenyl ester. In addition, from the viewpoint of improving melt retention stability, it is preferable to add an alkali compound such as sodium hydroxide, potassium hydroxide, or magnesium hydroxide.

The relative viscosity (RV) of the semi-aromatic crystalline polyamide resin (A1) measured in 96% concentrated sulfuric acid at 20°C is preferably 0.4 to 4.0, more preferably 1.0 to 3.0, and even more preferably 1.5 to 2.8. One method for keeping the relative viscosity of the polyamide within a certain range is to adjust the molecular weight.

The amount of terminal groups and molecular weight of the semi-aromatic crystalline polyamide resin (A1) can be adjusted by adjusting the molar ratio of amino groups to carboxyl groups and polycondensing the polyamide or by adding a terminal blocking agent.

The timing of adding the end-capping agent may include when the raw materials are charged, at the start of polymerization, in the later stages of polymerization, or at the end of polymerization. There are no particular limitations on the end-capping agent, so long as it is a monofunctional compound that is reactive with the amino or carboxyl groups at the polyamide terminals. Examples of the end-capping agent that can be used include monocarboxylic acids or monoamines, acid anhydrides such as phthalic anhydride, monoisocyanates, monoacid halides, monoesters, and monoalcohols. Examples of the end-capping agent include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; acid anhydrides such as maleic anhydride, phthalic anhydride, and hexahydrophthalic anhydride; aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; and aromatic monoamines such as aniline, toluidine, diphenylamine, and naphthylamine.

The semi-aromatic crystalline polyamide resin (A1) can be produced by a conventional method, and can be easily synthesized, for example, by subjecting raw material monomers to a co-condensation reaction. The order of the co-condensation polymerization reaction is not particularly limited, and all raw material monomers may be reacted at once, or some raw material monomers may be reacted first, followed by the remaining raw material monomers. The polymerization method is not particularly limited, and may be a continuous process from raw material charging to polymer production, or an oligomer may be produced once and then polymerized in a separate process using an extruder, or the oligomer may be polymerized by solid-phase polymerization. The ratio of each structural unit in the synthesized copolymerized polyamide can be controlled by adjusting the charging ratio of the raw material monomers.

The amorphous polyamide resin (A2) used in the present invention preferably has a Tg of 100°C to 200°C. The Tg is more preferably 120°C to 180°C, and even more preferably 120°C to 160°C. If the Tg of the amorphous polyamide resin (A2) is below the lower limit, the rigidity of the resin may decrease depending on the usage environment, which may cause defects in the product. If the Tg exceeds the upper limit, the flow of the resin inside the mold during injection molding may be hindered, which may lead to a deterioration in the appearance of the molded product and poor filling.

Examples of amorphous polyamide resins (A2) include PA6T6I, which is made of hexamethylenediamine, terephthalic acid, and isophthalic acid; PAMACMT, which is made of bis(3-methyl-4-aminocyclohexyl)methane and terephthalic acid; PAMACMI, which is made of bis(3-methyl-4-aminocyclohexyl)methane and isophthalic acid; PA12/MACMI, which is made of bis(3-methyl-4-aminocyclohexyl)methane, isophthalic acid, and 12-aminododecanoic acid; PAMACM12, which is made of bis(3-methyl-4-aminocyclohexyl)methane and dodecanedioic acid; and PAMACM14, which is made of bis(3-methyl-4-aminocyclohexyl)methane and tetradecanedioic acid. These polyamides may be used alone, or two or more of them may be used by copolymerization or blending.

As the amorphous polyamide resin (A2), PA6T6I is preferred. PA6T6I is an amorphous polyamide resin with a Tg of 125°C, which does not hinder the flow of the resin at the mold temperature during injection molding, making it easy to mold and producing a molded product with a good appearance.

The amorphous polyamide resin (A2) used in the present invention preferably has a relative viscosity (RV) in a 96% sulfuric acid solution at 20°C of 1.4 to 3.0. It is more preferable that the RV is 1.6 to 2.8, and even more preferable that the RV is 1.8 to 2.6.

In the polyamide resin (A), the semi-aromatic crystalline polyamide resin (A1) is contained in an amount of 70 to 99% by mass, and the amorphous polyamide resin (A2) is contained in an amount of 1 to 30% by mass. The semi-aromatic crystalline polyamide resin (A1) is preferably contained in an amount of 73 to 98% by mass, and the amorphous polyamide resin (A2) is preferably contained in an amount of 2 to 27% by mass, and more preferably, the semi-aromatic polyamide resin (A1) is contained in an amount of 75 to 97% by mass, and the amorphous polyamide resin (A2) is preferably contained in an amount of 3 to 25% by mass. If the amount of the amorphous polyamide resin (A2) is below the lower limit, the appearance of the molded product is deteriorated, which is not preferable. Also, if the amount of the amorphous polyamide resin (A2) exceeds the upper limit, it is not preferable because it may cause a decrease in rigidity in the usage environment.

There are no particular limitations on the carbon fiber (B) used in the present invention, so long as it has a fiber diameter of 3 to 10 μm and a tensile strength of 3.0 GPa or more. There are no particular limitations on the manufacturing method as long as it is a generally disclosed method, but PAN-based carbon fibers are preferred in order to improve mechanical properties. It is more preferable for the carbon fiber to have a strength of 4.5 GPa or more and a fiber diameter of 4.5 to 7.5 μm. There are no particular limitations on the upper limit of the strength of the carbon fiber, but it is preferable to use one with a strength of 6.0 GPa or less.

The carbon fiber (B) may have a coupling agent or a sizing agent attached to its surface in order to improve wettability with the resin and ease of handling. Examples of coupling agents include aminosilane, epoxysilane, and mercaptosilane, but aminosilane coupling agents are preferred for polyamide. Urethane and acrylic sizing agents are preferred. The amount of the coupling agent or sizing agent used is preferably 0.1 to 5 parts by mass per 100 parts by mass of carbon fiber, but is not particularly limited. When kneading with polyamide, the carbon fiber is preferably a chopped strand obtained by cutting a fiber bundle treated with the coupling agent or sizing agent to 3 to 8 mm.

The carbon fiber reinforced polyamide resin composition of the present invention contains 10 to 50 parts by mass of carbon fiber (B). The content of carbon fiber (B) is preferably 15 to 45 parts by mass. The content of carbon fiber (B) in the above range is preferable because it allows the molded product to exhibit high strength and excellent appearance, and also reduces the number of poorly dispersed and agglomerated foreign matter.

The carbon fiber reinforced polyamide resin composition of the present invention preferably contains 0.01 to 2.0 parts by mass of antioxidant (C). It is more preferable that the antioxidant (C) contains 0.05 to 1.5 parts by mass, and even more preferable that the antioxidant (C) contains 0.1 to 1.2 parts by mass. If the amount of antioxidant (C) is below the above lower limit, the desired effect of improving heat aging resistance may not be obtained. If the amount of antioxidant (C) exceeds the above upper limit, there is a possibility of deterioration in the appearance of the molded product due to bleed-out and an increase in outgassing during molding.

Examples of the antioxidant (C) include phenol-based antioxidants, phosphorus-based antioxidants, amine-based antioxidants, and sulfur-based antioxidants. These antioxidants may be used alone or in combination.

The carbon fiber reinforced polyamide resin composition of the present invention preferably contains 0.01 to 0.5 parts by mass of copper compound (D). It is more preferable that the composition contains 0.01 to 0.4 parts by mass, and even more preferable that the composition contains 0.02 to 0.3 parts by mass. Even without the copper compound (D), the carbon fiber reinforced polyamide resin composition has a certain level of heat aging resistance, but when heat aging resistance is particularly required, it is preferable to incorporate copper compound (D). On the other hand, if the amount of copper compound (D) exceeds the above upper limit, this may lead to a decrease in mechanical properties.

Examples of copper compounds (D) include copper chloride, copper bromide, copper iodide, copper acetate, copper acetylacetonate, copper carbonate, copper fluoroborate, copper citrate, copper hydroxide, copper nitrate, copper sulfate, and copper oxalate.

The carbon fiber reinforced polyamide resin composition of the present invention can be blended with other components (E) to the extent that the characteristics of the present invention are not impaired. Examples include various additives selected from stabilizers containing alkali halide compounds, inorganic fillers, impact modifiers, sliding materials, weather resistance modifiers containing carbon black, release agents, crystal nucleating agents, lubricants, flame retardants, antistatic agents, pigments, dyes, etc. The various additives can be contained (blended) in a total amount of up to 20 parts by mass per 100 parts by mass of the polyamide resin (A) and the carbon fiber (B). The carbon fiber reinforced polyamide resin composition of the present invention preferably contains 80% by mass or more of the essential components polyamide resin (A) and carbon fiber (B), more preferably 90% by mass or more, and even more preferably 95% by mass or more.

The number of poorly dispersed and agglomerated foreign particles in the carbon fiber reinforced polyamide resin composition of the present invention is measured by the method described in the Examples section below. In order to produce a good molded product, the number of poorly dispersed and agglomerated foreign particles must be 15 or less. It is also preferable that the number is 10 or less, more preferably 5 or less, and even more preferably 1 or less. If the number of poorly dispersed and agglomerated foreign particles exceeds the above upper limit, this is not preferable as it will lead to a deterioration in the appearance of the molded product. If the number of poorly dispersed and agglomerated foreign particles is 5 or less, it can be determined that there are very few agglomerated foreign particles in the molded product.

The carbon fiber reinforced polyamide resin composition of the present invention is not particularly limited in terms of the manufacturing method, and each component can be melt-kneaded by a conventionally known kneading method. There is no particular limit to the specific kneading device, and examples include single-screw or twin-screw extruders, kneaders, kneaders, etc., but twin-screw extruders are particularly preferred in terms of productivity. However, in order to produce a carbon fiber reinforced polyamide resin composition in which each component is more uniformly dispersed and there is no number of poorly dispersed and agglomerated foreign matter, when the length of the barrel from the main feed position of the kneading device to the die is 100, and the most upstream main feed is set as the kneading start position and is set to 0, it is preferable to melt-knead only in one kneading zone by side feed supply from a barrel position of 50 to 80, which is the standard supply method for fiber-based reinforcing materials such as glass fiber, but to side feed carbon fiber (B) from a barrel position of 30 to 45 on the upstream side and melt-knead in two or more kneading zones. A specific preferred method is to pre-blend the semi-aromatic crystalline polyamide resin (A1), the amorphous polyamide resin (A2), the antioxidant (C), the copper compound (D), and other additive components (E) in a blender, and then feed them from a hopper into a single-screw or twin-screw extruder. Thereafter, while at least a portion of (A1) and (A2) is in a molten state, carbon fiber (B) is fed into the molten mixture by a feeder at the barrel position described above, and the mixture is melt-kneaded and then discharged in the form of a strand, which is then cooled and cut.

The carbon fiber reinforced polyamide resin composition of the present invention can be molded by conventional methods such as extrusion molding, injection molding, and compression molding. The molded products formed have excellent strength, appearance, strength retention after water absorption, and low agglomeration foreign matter, and can be used for various applications. Specific examples include, but are not limited to, various electrical and electronic parts such as connectors and switches, housing parts, automobile parts, and sports parts.

The carbon fiber reinforced polyamide resin composition of the present invention not only has excellent strength, appearance, and strength retention after absorbing water, but also reduces the number of poorly dispersed and agglomerated foreign matter, making it possible to provide molded products that highly satisfy user needs.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The measured values described in the examples were measured by the following methods.

(1) Relative Viscosity (RV)
0.25 g of the polyamide resin was dissolved in 25 ml of 96% sulfuric acid, and the viscosity was measured at 20° C. using an Ostwald viscometer.

(2) Terminal carboxyl group concentration (CEG)
Semi-aromatic polyamide resin (A1) was dissolved in a solvent of deuterated chloroform (CDCl ₃ )/hexafluoroisopropanol (HFIP)=1/1 (volume ratio), polyformic acid was added dropwise, and the terminal carboxyl group concentration was measured by ¹ H-NMR.

(3) Melting point (Tm)
10 mg of semi-aromatic crystalline polyamide resin (A1) dried under reduced pressure at 105 ° C for 15 hours was weighed into an aluminum pan (manufactured by SII Nanotechnology, product number 170421S) and sealed with an aluminum lid (manufactured by SII Nanotechnology, product number 170420) to prepare a measurement sample, and then the sample was heated from room temperature at 20 ° C / min using a high-sensitivity differential scanning calorimeter DSC7020 (manufactured by SII Nanotechnology), held at 350 ° C for 3 minutes, and then the measurement sample pan was taken out and immersed in liquid nitrogen to be rapidly cooled. Thereafter, the sample was taken out of the liquid nitrogen and left at room temperature for 30 minutes, and then again heated from room temperature at 20 ° C / min using a high-sensitivity differential scanning calorimeter DSC7020 (manufactured by SII Nanotechnology), and held at 350 ° C for 3 minutes. The peak temperature of the endothermic heat due to melting during heating was taken as the melting point (Tm).

(4) Glass transition temperature (Tg)
Polyamide resin (A) dried under reduced pressure at 105 ° C for 15 hours was weighed out in an aluminum pan (manufactured by SII Nanotechnology Co., Ltd., product number 170421S) in an amount of 10 mg, and sealed with an aluminum lid (manufactured by SII Nanotechnology Co., Ltd., product number 170420) to prepare a measurement sample, and then heated from room temperature at 20 ° C / min using a high-sensitivity differential scanning calorimeter DSC7020 (manufactured by SII Nanotechnology Co., Ltd.), held at 350 ° C for 3 minutes, and then the measurement sample pan was removed and immersed in liquid nitrogen to be quenched. Thereafter, the sample was removed from the liquid nitrogen, left at room temperature for 30 minutes, and then heated again from room temperature at 20 ° C / min using a high-sensitivity differential scanning calorimeter DSC7020 (manufactured by SII Nanotechnology Co., Ltd.) and held at 350 ° C for 3 minutes. The inflection point of the baseline during heating was taken as the glass transition temperature (Tg).

(5) Flexural strength, flexural strength retention rate when absorbing water Using a Toshiba Machine IS-80 injection molding machine, the cylinder temperature was set to the melting point of the semi-aromatic crystalline polyamide resin (A1) + 20°C, the mold temperature was set to 140°C, and a test piece for evaluation was prepared in accordance with ISO-178. The physical properties were evaluated, and the result was taken as the flexural strength when completely dry. In addition, the test piece was left to stand for 1000 hours in an atmosphere of 80°C and 95% RH (relative humidity), and then the flexural properties were evaluated in accordance with ISO-178. The result was taken as the flexural strength when saturated with water. The flexural strength retention rate when absorbing water was calculated from the following formula.
Bending strength retention rate when absorbing water (%)=(bending strength when saturated with water/bending strength when completely dry)×100

(6) Surface Appearance of Molded Articles Using a Toshiba Machine IS-80 injection molding machine, a test piece having a length of 100 mm, a width of 100 mm, and a thickness of 2 mm was produced by injection molding at a cylinder temperature of the melting point of the semi-aromatic crystalline polyamide resin (A1) + 20°C, a mold temperature of 140°C, and an injection speed of 40%. The appearance of the test piece was evaluated visually, and those without fiber floating were marked with ○, and those with fiber floating were marked with ×.

(7) Number of poorly dispersed and agglomerated foreign matter in molded products Using an injection molding machine IS-80 manufactured by Toshiba Machine, the cylinder temperature was set to the melting point of the semi-aromatic crystalline polyamide resin (A1) + 20°C, the mold temperature was set to 140°C, the injection speed was set to 60%, the dwell pressure was set to 25%, the injection dwell time was set to 10 seconds, and the cooling time was set to 12 seconds, and a test piece for testing with a length of 100 mm, a width of 100 mm, and a thickness of 1 mm was produced by injection molding. Using 10 test pieces for testing, the poorly dispersed and agglomerated foreign matter was counted. The number of poorly dispersed and agglomerated foreign matter is the number per 10 test pieces. In addition, when poorly dispersed and agglomerated foreign matter is mixed in, it is visible on the surface of the molded product with a size of 0.5 mm or more, so it can be confirmed visually.

This example was carried out using the semi-aromatic crystalline polyamide resin (A1) synthesized as shown in the following example. The physical properties of the synthesized semi-aromatic crystalline polyamide resin (A1) are shown in Table 1.

<Semi-aromatic crystalline polyamide resin (A1-1) - Synthesis example 1>
8.55 kg of 1,6-hexamethylenediamine, 12.25 kg of terephthalic acid, 8.00 kg of 11-aminoundecanoic acid, 9 g of sodium hypophosphite as a catalyst, 140 g of acetic acid as a terminal regulator, and 16.20 kg of ion-exchanged water were charged into a 50-liter autoclave, pressurized from normal pressure to 0.05 MPa with _N2 , released, and returned to normal pressure. This operation was performed three times, and after _N2 replacement, the mixture was uniformly dissolved at 135°C and 0.3 MPa under stirring. Thereafter, the solution was continuously supplied by a liquid delivery pump, heated to 240°C by a heating pipe, and heated for 1 hour. The reaction mixture was then supplied to a pressurized reaction vessel, heated to 290°C, and a portion of the water was distilled off so as to maintain the internal pressure of the vessel at 3 MPa, to obtain a low-order condensate. Thereafter, this low-order condensate was directly fed to a twin-screw extruder (screw diameter 37 mm, L/D=60) while maintaining the molten state, and polycondensation was carried out under molten conditions while removing water from three vents at a resin temperature of 335°C, to obtain a semi-aromatic crystalline polyamide resin (A1-1). The obtained semi-aromatic crystalline polyamide resin (A1-1) was composed of 65.1 mol% of structural units consisting of 1,6-hexamethylenediamine and terephthalic acid and 34.9 mol% of structural units consisting of 11-aminoundecanoic acid, had a relative viscosity of 2.1, a melting point of 314°C, and an AEG (terminal amino group concentration) of 20 eq/ton and a CEG of 140 eq/ton as analyzed by ¹ H-NMR.

<Semi-aromatic crystalline polyamide resin (A1-2) - Synthesis example 2>
The amount of 1,6-hexamethylenediamine was changed to 9.20 kg, the amount of terephthalic acid was changed to 12.25 kg, the amount of 11-aminoundecanoic acid was changed to 8.00 kg, sodium hypophosphite was used as a catalyst to 9 g, acetic acid as an end-capping agent to 330 g, and ion-exchanged water to 16.20 kg, and a semi-aromatic crystalline polyamide resin (A1-2) was obtained in the same manner as polyamide (A1-1). The obtained semi-aromatic crystalline polyamide resin (A1-2) was composed of 64.8 mol% of structural units consisting of 1,6-hexamethylenediamine and terephthalic acid, and 35.2 mol% of structural units consisting of 11-aminoundecanoic acid, and had a relative viscosity of 2.1, a melting point of 315°C, and an AEG of 30 eq/ton and a CEG of 30 eq/ton as analyzed by ¹ H-NMR.

<Semi-aromatic crystalline polyamide resin (A1-3) - Synthesis example 3>
The amount of 1,6-hexamethylenediamine was changed to 9.00 kg, the amount of terephthalic acid was changed to 12.25 kg, the amount of 11-aminoundecanoic acid was changed to 8.00 kg, sodium hypophosphite was used as a catalyst to 9 g, acetic acid was used as an end-capping agent to 255 g, and ion-exchanged water was used to 16.20 kg, and a semi-aromatic crystalline polyamide resin (A1-3) was obtained in the same manner as polyamide (A1-1). The obtained semi-aromatic crystalline polyamide resin (A1-3) was composed of 64.9 mol% of structural units consisting of 1,6-hexamethylenediamine and terephthalic acid, and 35.1 mol% of structural units consisting of 11-aminoundecanoic acid, and had a relative viscosity of 2.1, a melting point of 315°C, and an AEG of 30 eq/ton and a CEG of 70 eq/ton as analyzed by ¹ H-NMR.

In the present examples and comparative examples, the following raw materials were used.
Semi-aromatic crystalline polyamide resin (A1-1): Semi-aromatic crystalline polyamide resin prepared according to the above Synthesis Example 1. Semi-aromatic crystalline polyamide resin (A1-2): Semi-aromatic crystalline polyamide resin prepared according to the above Synthesis Example 2. Semi-aromatic crystalline polyamide resin (A1-3): Semi-aromatic crystalline polyamide resin prepared according to the above Synthesis Example 3. Amorphous polyamide resin (A2-1): PA6T6I, EMS "Grivory(R) G21", Tg 125°C.
Amorphous polyamide resin (A2-2): PA12/MACMI, "Grilamide(R) TR55" manufactured by EMS, Tg 160°C
Polyamide resin (A3): PAMXD6 (polymetaxylylene adipamide), Toyobo Nylon (R) T600 manufactured by Toyobo Co., Ltd., Tm 237°C, Tg 80°C
Carbon fiber (B-1): "CFUW-LC-HS" manufactured by Japan Polymer Industries, fiber diameter 5.5 μm, cut length 6 mm, tensile strength 5.5 GPa
Carbon fiber (B-2): "CFUW-MC" manufactured by Nippon Polymer Industries Co., Ltd., fiber diameter 7 μm, cut length 6 mm, tensile strength 4.9 GPa
Antioxidant (C): "Irganox(R) 1010" manufactured by BASF, pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]
Copper compound (D): Copper(II) bromide
Release agent (E): Magnesium stearate Glass fiber (F): Glass fiber "T-275H" manufactured by Nippon Electric Glass Co., Ltd., fiber diameter 11 μm

<Examples 1 to 10>
The components other than carbon fiber (B) were dry blended in the blending ratio shown in Table 2, and melt mixed under the extrusion conditions of a cylinder temperature set to Tm+15°C of the semi-aromatic crystalline polyamide resin (A1) using a vented twin-screw extruder "STS35mm" (barrel 12 block configuration) manufactured by Coperion, and a screw rotation speed of 250 rpm. Then, carbon fiber (B) was fed from the upstream side at a position 42 when the barrel length from the main feed position to the die was set to 100 by a side feed method, and melt kneaded. The strands extruded from the twin-screw extruder were quenched and pelletized using a strand cutter. The obtained pellets were dried at 100°C for 12 hours, and then various test specimens were molded using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., IS-80) at a cylinder temperature of Tm+20°C of the semi-aromatic crystalline polyamide resin (A1) and a mold temperature of 140°C, and subjected to evaluation.

As is clear from Table 2, the carbon fiber reinforced polyamide resin compositions of Examples 1 to 10, by incorporating semi-aromatic crystalline polyamide resin (A1) and amorphous polyamide resin (A2) and by adjusting the position of carbon fiber (B) in the manufacturing process, are excellent in strength retention after saturation water absorption, surface appearance of molded products, and poorly dispersed carbon fiber agglomerates. In addition, in Examples 9 and 10, the number of poorly dispersed agglomerates was 12 and 5, respectively, but by changing the CEG of the semi-aromatic crystalline polyamide resin (A1), the number of poorly dispersed agglomerates could be reduced, as in Example 1.

<Comparative Examples 1 and 2>
The components other than carbon fiber (B) were dry blended in the blending ratio shown in Table 3, and melt mixed under the extrusion conditions of a cylinder temperature set to Tm+15°C of the semi-aromatic crystalline polyamide resin (A1) using a vented twin-screw extruder "STS35mm" (12-block barrel configuration) manufactured by Coperion, and a screw rotation speed of 250 rpm. Then, carbon fiber (B) was fed from the upstream side at position 67 by side feed method when the barrel length from the main feed position to the die was 100, and melt kneaded. The strands extruded from the twin-screw extruder were quenched and pelletized using a strand cutter. The obtained pellets were dried at 100°C for 12 hours, and then various test specimens were molded using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., IS-80) at a cylinder temperature of Tm+20°C of the semi-aromatic crystalline polyamide resin (A1) and a mold temperature of 140°C, and subjected to evaluation.

<Comparative Examples 3 to 5>
The components other than carbon fiber (B) were dry blended in the blending ratio shown in Table 3, and melt mixed under the extrusion conditions of a cylinder temperature set to Tm+15°C of the semi-aromatic crystalline polyamide resin (A1) using a vented twin-screw extruder "STS35mm" (barrel 12 block configuration) manufactured by Coperion, and a screw rotation speed of 250 rpm. Then, carbon fiber (B) was fed from the upstream side at a position 42 by a side feed method when the barrel length from the main feed position to the die was 100, and melt kneaded. The strands extruded from the twin-screw extruder were quenched and pelletized using a strand cutter. The obtained pellets were dried at 100°C for 12 hours, and then various test specimens were molded using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., IS-80) at a cylinder temperature of Tm+20°C of the semi-aromatic crystalline polyamide resin (A1) and a mold temperature of 140°C, and subjected to evaluation.

<Reference Examples 1 and 2>
The components other than the glass fiber (F) were dry-blended in the proportions shown in Table 3, and melt-mixed under the extrusion conditions of a cylinder temperature set to Tm+15°C of the semi-aromatic crystalline polyamide resin (A1) using a vented twin-screw extruder "STS35mm" (12-block barrel configuration) manufactured by Coperion, and a screw rotation speed of 250 rpm. Next, the glass fiber (F) was fed from the upstream side at a position 67 (Reference Example 1) or 42 (Reference Example 2) using a side feed method, when the length of the barrel from the main feed position to the die was 100, and melt-kneaded. The strands extruded from the twin-screw extruder were quenched and pelletized using a strand cutter. The obtained pellets were dried at 100°C for 12 hours, and then various test specimens were molded using an injection molding machine (Toshiba Machine Co., Ltd., IS-80) at a cylinder temperature of Tm+20°C of the semi-aromatic crystalline polyamide resin (A1) and a mold temperature of 140°C, and subjected to evaluation.

In Comparative Examples 1 and 2, the carbon fiber (B) was not supplied to the correct position during the manufacturing process, resulting in a large amount of poorly dispersed carbon fiber aggregates, making the carbon fiber reinforced polyamide resin composition insufficient. In Comparative Examples 3 and 4, the absence of amorphous polyamide resin (A2) resulted in a deterioration in surface appearance, making the carbon fiber reinforced polyamide resin composition insufficient. In Comparative Example 5, the strength retention rate after saturated water absorption was reduced by changing the amorphous polyamide resin (A2) to polyamide resin (A3), making the carbon fiber reinforced polyamide resin composition insufficient.

As can be seen from Reference Examples 1 and 2, when glass fiber (F) is used, no poorly dispersed agglomerates are generated regardless of the supply position.

The carbon fiber reinforced polyamide resin composition of the present invention is excellent in strength, appearance, strength retention after water absorption, and poorly dispersed foreign matter agglomeration number. Molded articles using the carbon fiber reinforced polyamide resin composition can be suitably used as housings for electronic and electrical parts, vehicle parts used in the interior and exterior of automobiles, and sports and leisure parts.

Claims (7)

A carbon fiber reinforced polyamide resin composition comprising 50 to 90 parts by mass of a polyamide resin (A) and 10 to 50 parts by mass of a carbon fiber (B),
the polyamide resin (A) contains 70 to 99 mass% of a semi-aromatic crystalline polyamide resin (A1) having terephthalic acid as a constituent component and 1 to 30 mass% of a non-crystalline polyamide resin (A2);
the semi-aromatic crystalline polyamide resin (A1) is a semi-aromatic polyamide resin containing 50 to 100 mol % of repeating units consisting of a diamine having 6 to 12 carbon atoms and terephthalic acid, and 0 to 50 mol % of repeating units consisting of an aminocarboxylic acid or lactam having 10 or more carbon atoms, and the terminal carboxyl group concentration (CEG) of the semi-aromatic crystalline polyamide resin (A1) is 40 eq/ton or more,
The amorphous polyamide resin (A2) is a polyamide selected from PA6T6I consisting of hexamethylenediamine, terephthalic acid, and isophthalic acid, PAMACMT consisting of bis(3-methyl-4-aminocyclohexyl)methane and terephthalic acid, PAMACMI consisting of bis(3-methyl-4-aminocyclohexyl)methane and isophthalic acid, PA12/MACMI consisting of bis(3-methyl-4-aminocyclohexyl)methane, isophthalic acid, and 12-aminododecanoic acid, PAMACM12 consisting of bis(3-methyl-4-aminocyclohexyl)methane and dodecanedioic acid, and PAMACM14 consisting of bis(3-methyl-4-aminocyclohexyl)methane and tetradecanedioic acid, and may be used alone or in the form of two or more kinds by copolymerization or blending.
The carbon fiber reinforced polyamide resin composition is injection molded to obtain 10 flat plate test pieces each having a length of 100 mm, a width of 100 mm and a thickness of 1 mm. The number of poorly dispersed agglomerated foreign matter particles having a size of 0.5 mm or more and visible on the surface of the flat plate test pieces is 10 or less. The carbon fiber reinforced polyamide resin composition according to claim 1 , further comprising 0.01 to 2.0 parts by mass of an antioxidant (C) relative to a total of 100 parts by mass of the polyamide resin (A) and the carbon fiber (B). The carbon fiber reinforced polyamide resin composition according to claim 1 or 2 , further comprising 0.01 to 0.5 parts by mass of a copper compound (D) relative to a total of 100 parts by mass of the polyamide resin (A) and the carbon fiber (B). A molded article comprising the carbon fiber reinforced polyamide resin composition according to any one of claims 1 to 3 . A method for producing a carbon fiber reinforced polyamide resin composition, comprising the steps of:
The carbon fiber reinforced polyamide resin composition contains 50 to 90 parts by mass of a polyamide resin (A) and 10 to 50 parts by mass of carbon fiber (B),
the polyamide resin (A) contains 70 to 99 mass% of a semi-aromatic crystalline polyamide resin (A1) having terephthalic acid as a constituent component and 1 to 30 mass% of a non-crystalline polyamide resin (A2);
the semi-aromatic crystalline polyamide resin (A1) is a semi-aromatic polyamide resin containing 50 to 100 mol % of repeating units consisting of a diamine having 6 to 12 carbon atoms and terephthalic acid, and 0 to 50 mol % of repeating units consisting of an aminocarboxylic acid or lactam having 10 or more carbon atoms, and the terminal carboxyl group concentration (CEG) of the semi-aromatic crystalline polyamide resin (A1) is 40 eq/ton or more,
The amorphous polyamide resin (A2) is a polyamide selected from PA6T6I consisting of hexamethylenediamine, terephthalic acid, and isophthalic acid, PAMACMT consisting of bis(3-methyl-4-aminocyclohexyl)methane and terephthalic acid, PAMACMI consisting of bis(3-methyl-4-aminocyclohexyl)methane and isophthalic acid, PA12/MACMI consisting of bis(3-methyl-4-aminocyclohexyl)methane, isophthalic acid, and 12-aminododecanoic acid, PAMACM12 consisting of bis(3-methyl-4-aminocyclohexyl)methane and dodecanedioic acid, and PAMACM14 consisting of bis(3-methyl-4-aminocyclohexyl)methane and tetradecanedioic acid, and may be used alone or in the form of two or more kinds by copolymerization or blending.
A method for producing a carbon fiber reinforced polyamide resin composition, characterized in that, in a state in which at least a portion of the semi-aromatic crystalline polyamide resin (A1) and the amorphous polyamide resin (A2) are melted, the carbon fibers (B) are side-fed to the melt from a barrel position 30 to 45 upstream, where the barrel length from the main feed position of a kneading device to a die is 100, and the most upstream main feed is set as the kneading start position and is 0. The carbon fiber reinforced polyamide resin composition further comprises 0.01 to 2.0 parts by mass of an antioxidant (C) relative to a total of 100 parts by mass of the polyamide resin (A) and the carbon fiber (B). The method for producing a carbon fiber reinforced polyamide resin composition according to claim 5 . The carbon fiber reinforced polyamide resin composition further comprises 0.01 to 0.5 parts by mass of a copper compound (D) relative to a total of 100 parts by mass of the polyamide resin (A) and the carbon fiber (B). The method for producing a carbon fiber reinforced polyamide resin composition according to claim 5 or 6 .