TWI869372B - Carbon fiber reinforced polyamide resin composition and molded product thereof - Google Patents

Abstract

The present invention is a carbon fiber reinforced polyamide resin composition, which has excellent strength, appearance of molded products, and strength retention rate after water absorption, and has little poor dispersion and agglomeration of foreign matter. The carbon fiber reinforced polyamide resin composition contains 50 to 90 parts by weight of polyamide resin (A) and 10 to 50 parts by weight of carbon fiber (B); the polyamide resin (A) contains terephthalic acid A carbon fiber reinforced polyamide resin composition is injection molded with 70-99 mass % of a semi-aromatic crystalline polyamide resin (A1) and 1-30 mass % of a non-crystalline polyamide resin (A2) as constituent components, and the number of poorly dispersed agglomerated foreign particles in a flat test piece having a length of 100 mm, a width of 100 mm, and a thickness of 1 mm is 15 or less.

Description

Carbon fiber reinforced polyamide resin composition and molded product thereof

The present invention relates to a 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, and is light and strong. In particular, the present invention relates to a polyamide resin composition with a very low water absorption rate and a small drop in the glass transition temperature when absorbing water, so that the strength of the molded product does not decrease even if it absorbs water, and the molded product has excellent appearance and toughness. The polyamide resin composition of the present invention can be suitably used as parts that were previously made of metal, such as housings of electronic and electrical parts, vehicle parts used in automobile interior and exterior, or sports and leisure parts.

Polyamide resins are reinforced by kneading carbon fibers with an extruder, which not only exhibits high strength and rigidity, but also high load flexibility. Therefore, carbon fiber reinforced polyamide resin compositions are widely used in electronic and electrical equipment or in the fields of automobiles, motorcycles, bicycles, and other vehicles as internal and external components. In recent years, especially considering the thinning of electronic and electrical components, the miniaturization of vehicle parts, and the lightweighting brought about by metal substitutes, there is a higher demand for lighter and stronger ones, and a thermoplastic resin composition with higher specific strength expressed by strength/specific gravity is sought. However, polyamide resin compositions generally have a high water absorption rate, and if they absorb water, their strength and elastic modulus will decrease. Therefore, for example, glass fiber reinforced polyamide resin compositions based on polyamide 6 and polyamide 66 components have the disadvantage of reduced strength when absorbing water. In addition, although the water absorption rate is low depending on the type of polyamide, if the amount of carbon fiber filling increases, the fiber destruction and short fiberization will be intense during melt kneading. Although the specific gravity (density) becomes higher, the strength is insufficient, and the appearance of the molded product is also worse than the amount of carbon fiber added, so the quality is poor. In addition, although the water absorption rate is low, there are many types of polyamides whose glass transition temperature drops greatly when absorbing water, causing a decrease in strength and elastic modulus. Therefore, their use as housings for electronic and electrical parts, automotive parts used in automobile interiors and exteriors, or sports and leisure parts is limited.

In addition, in recent years, especially in the installation of electrical and electronic parts, the surface mounting method (flow soldering method, reflow soldering method) has been rapidly and widely used because of the miniaturization of parts, high density of mounting, simplification of steps or cost reduction along with the miniaturization of product size. In the surface mounting method, considering that the step environment temperature is above the melting temperature of solder (240~260℃), the resin used must also be heat-resistant at the above-mentioned environment temperature. In addition, in the surface mounting step, there is also the problem of swelling and deformation of the mounted parts due to water absorption of the resin, and the resin used is required to have low water absorption. Resins satisfying these characteristics include 6T polyamide and 9T polyamide. For example, Patent Document 1 or Patent Document 2 discloses that these aromatic polyamides can be used in surface-mounted electrical and electronic components.

Patent document 3 proposes a method of adding specific carbon fibers to polyamide 6 for the purpose of weight reduction and high rigidity. However, polyamide 6 has a problem that its elastic modulus or strength decreases significantly due to water absorption.

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

In Patent Document 5, a carbon fiber reinforced polyamide resin composition is proposed, which has excellent mechanical properties and appearance by combining a specific polyamide resin and a specific carbon fiber in a relatively small range of specific addition amounts. However, there is no proposal for a high-filled carbon fiber reinforced polyamide resin composition that is free of poorly dispersed agglomerated foreign matter, is sufficiently strong and light, and has high physical properties even after absorbing water. [Prior Technical Document] [Patent Document]

Patent document 1: Japanese Patent Publication No. 3-88846 Patent document 2: Japanese Patent Publication No. 3474246 Patent document 3: Japanese Patent Publication No. 2006-1964 Patent document 4: Japanese Patent Publication No. 2012-255063 Patent document 5: Japanese Patent Publication No. 6210217

[The problem that the invention wants to solve]

When making carbon fiber reinforced polyamide resin compositions, carbon fibers are more difficult to disperse and defibrinate evenly than glass fibers, and it is difficult to ensure a stable dispersion state. Poor fiber dispersion makes it difficult to obtain a good surface state of the molded product. In addition, if excessive mixing is performed to obtain a good surface state of the molded product, the fiber will be destroyed and short-fibered, and sufficient strength cannot be obtained. Therefore, it is an important issue to have both uniform dispersion and strength of carbon fibers. The present invention was created in view of the current state of the above-mentioned prior art. The subject is to provide a polyamide resin composition that has no poor dispersion 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 has a high carbon fiber filling amount. [Means for solving the problem]

As a result of in-depth research to achieve this purpose, the inventors of this case discovered that by using specific crystalline polyamide resins and non-crystalline polyamide resins among various polyamide resins, adding a certain range of carbon fibers and performing melt kneading, and then side feeding from the upstream side, a carbon fiber reinforced polyamide resin composition with good appearance, sufficient strength and lightness, and high physical properties even after absorbing water can be obtained.

That is, the present invention adopts the following (1) to (6) structures. (1) 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 carbon fiber (B); the polyamide resin (A) comprises 70 to 99% by mass of a semi-aromatic crystalline polyamide resin (A1) having terephthalic acid as a constituent and 1 to 30% by mass of a non-crystalline polyamide resin (A2); and the number of poorly dispersed agglomerated foreign matters in a flat plate 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) A carbon fiber reinforced polyamide resin composition as described in (1), wherein the terminal carboxyl concentration (CEG) of the semi-aromatic crystalline polyamide resin (A1) containing terephthalic acid as a component is 40 eq/ton or more. (3) A carbon fiber reinforced polyamide resin composition as described in (1) or (2), further comprising an antioxidant (C) in an amount of 0.01 to 2.0 parts by weight relative to 100 parts by weight of the total of the polyamide resin (A) and the carbon fiber (B). (4) A carbon fiber reinforced polyamide resin composition as described in any one of (1) to (3), further comprising a copper compound (D) in an amount of 0.01 to 0.5 parts by weight relative to 100 parts by weight of the total of the polyamide resin (A) and the carbon fiber (B). (5) A molded article, comprising a carbon fiber reinforced polyamide resin composition as described in any one of (1) to (4). [Effect of the invention]

The carbon fiber reinforced polyamide resin composition of the present invention specifies the types and amounts of polyamide resin and carbon fiber as specific types and amounts, and when adding a certain range of carbon fiber for melt kneading, the side feeding is performed from the upstream side compared to the standard feeding position of fiber-based reinforcing materials such as glass fiber, thereby forming a molded product with good appearance, strong and light, extremely low water absorption, and extremely little strength reduction caused by water absorption. It is very useful as a housing for electronic and electrical parts, vehicle parts used in automobile interior and exterior, or sports and leisure parts.

The carbon fiber reinforced polyamide resin composition of the present invention contains a polyamide resin (A) and a carbon fiber (B). The content (blending amount) of each component in the carbon fiber reinforced polyamide resin composition, unless otherwise specified, represents the amount when the total of the polyamide resin (A) and the carbon fiber (B) is 100 parts by mass. The polyamide resin (A) contains a semi-aromatic crystalline polyamide resin (A1) containing terephthalic acid as a component and a non-crystalline polyamide resin (A2), and the content ratio (blending ratio) of (A1) and (A2) is the ratio (mass %) when the polyamide resin (A) is 100 mass % unless otherwise specified. In the present invention, a non-crystalline polyamide resin is a polyamide resin that does not show a clear melting point peak when the polyamide resin is subjected to DSC measurement at a heating rate of 20°C/min in accordance with JIS K7121:2012. On the contrary, a polyamide resin that shows a clear melting point peak is a crystalline polyamide resin. In the present invention, the blending amount (blending ratio) of each component is the content (content ratio) in the carbon fiber reinforced polyamide resin composition.

The carbon fiber reinforced polyamide resin composition of the present invention contains 50-90 parts by weight of polyamide resin (A). The content of polyamide resin (A) is preferably 55-85 parts by weight. When the content of polyamide resin (A) is within the above range, the molded product not only exhibits high strength and excellent molded product appearance, but also reduces the number of poorly dispersed agglomerated foreign matter, which is more ideal.

The semi-aromatic crystalline polyamide resin (A1) used in the present invention has no particular limitation except that it is composed of terephthalic acid, and is a semi-aromatic polyamide having an amide bond (-CONH-) in the molecule. As an example of the semi-aromatic crystalline polyamide resin (A1) having terephthalic acid as a component (hereinafter sometimes referred to as the semi-aromatic crystalline polyamide resin (A1)), there can be mentioned 6T series polyamides (e.g., polyamide 6T6I composed of terephthalic acid/isophthalic acid/hexamethylenediamine, polyamide 6T66 composed of terephthalic acid/adipic acid/hexamethylenediamine, polyamide 6T6I66 composed of terephthalic acid/isophthalic acid/adipic acid/hexamethylenediamine, polyamide 6T6I66 composed of terephthalic acid/hexamethylenediamine The polyamides include polyamide 6T/M-5T composed of terephthalic acid/hexamethylenediamine/2-methyl-1,5-pentamethylenediamine, polyamide 6T6 composed of terephthalic acid/hexamethylenediamine/ε-caprolactam, polyamide 6T/4T composed of terephthalic acid/hexamethylenediamine/tetramethylenediamine), 9T series polyamide (terephthalic acid/1,9-nonanediamine/2-methyl-1,8-octanediamine), 10T series polyamide (terephthalic acid/1,10-decanediamine), 12T series polyamide (terephthalic acid/1,12-dodecanediamine), etc.

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 addition, in order to significantly demonstrate the effect of the present invention, CEG is more preferably 40 eq/ton or more, further preferably 50 eq/ton or more, and particularly preferably 60 eq/ton or more. When CEG is lower than the above lower limit, the compatibility with carbon fibers is reduced, resulting in a tendency to reduce strength or poor dispersion of carbon fibers. Although there is no particular upper limit for CEG, it is preferably 200 eq/ton or less, more preferably 190 eq/ton or less, and further preferably 180 eq/ton or less from the viewpoint of manufacturing stability.

The semi-aromatic crystalline polyamide resin (A1) used in the present invention preferably has a DSC melting peak temperature (Tm) of 280°C or more on the lowest temperature side measured by the method described in the items of the following embodiments. In addition, it is more preferably 290°C or more, and further preferably 300°C or more. In the case where Tm is lower than the above lower limit, there is a possibility that the formed body will melt or deform when the formed body of the present invention is processed by the solder reflow step. As for the upper limit of Tm, it is preferably below 340°C, more preferably below 330°C, and further preferably below 320°C. When Tm exceeds the above upper limit, there is a possibility that the processing temperature during the forming process is extremely high, and the resin may be decomposed due to heat.

The semi-aromatic crystalline polyamide resin (A1) used in the present invention is preferably the following semi-aromatic polyamide resin from the viewpoint of melting point (Tm) and glass transition temperature (Tg). 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 more than 10 carbon atoms; more preferably a semi-aromatic polyamide resin containing 50 to 90 mol% of repeating units consisting of a diamine having 6 to 12 carbon atoms and terephthalic acid. 8 mol%, a semi-aromatic polyamide resin containing 2-50 mol% of repeating units composed of aminocarboxylic acid or lactam with more than 10 carbon atoms; preferably, a semi-aromatic polyamide resin containing 55-98 mol% of repeating units composed of diamine with 6-12 carbon atoms and terephthalic acid, and 2-45 mol% of repeating units composed of aminocarboxylic acid or lactam with more than 10 carbon atoms. When the ratio of the repeating units composed 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%, the moldability decreases along with the decrease in crystallinity, and there is a possibility that problems may arise, such as melting or deformation of the molded body in the solder reflow step due to the decrease in Tm, and softening of the molded body in the use environment due to the decrease in Tg. On the other hand, it is more desirable to set the ratio of the repeating units composed 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, because Tm and Tg can be appropriately improved.

As the diamine component having 6 to 12 carbon atoms constituting the semiaromatic polyamide resin (A1), there can be mentioned 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 2-methyl-1,8-octamethylenediamine, 1,10-decamethylenediamine, 1,11-undemethylenediamine, and 1,12-dodecamethylenediamine. These can be used alone or in combination.

The aminocarboxylic acid having 10 or more carbon atoms or the lactam having 10 or more carbon atoms constituting the semiaromatic crystalline polyamide resin (A1) is preferably an aminocarboxylic acid or lactam having 11 to 18 carbon atoms. Among them, 11-aminoundecanoic acid, undecanoyl lactam, 12-aminododecanoic acid, and 12-lauryl lactam are preferred.

The semi-aromatic crystalline polyamide resin (A1) used in the present invention may be copolymerized with other components in an amount of 50% or less of the constituent 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 piperidine, cyclohexanediamine, bis(3-methyl-4-aminohexyl)methane, bis(4,4'-aminocyclohexyl)methane, 1,3-bisaminomethylcyclohexane, and isophoronediamine; aromatic diamines such as meta-phenylenediamine, para-phenylenediamine, para-phenylenediamine, and meta-phenylenediamine, and their hydrogenated products.

As for the copolymerizable acid component, there can be mentioned aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, 1,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 4,4'-diphenyl dicarboxylic acid, 2,2'-diphenyl dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 5-sodium sulfonate of isophthalic acid, 5-hydroxyisophthalic acid; fumaric acid, maleic acid, succinic acid, isophthalic acid, and 1,2-diisophthalic acid. aliphatic or alicyclic dicarboxylic acids such as conic 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, dimer acid, etc. In addition, as copolymerizable components, ε-caprolactam, etc. can be listed.

Among the above components, in view of Tm and Tg, as the copolymerization component, one or more of aminocarboxylic acid having 11 to 18 carbon atoms or lactam having 11 to 18 carbon atoms are preferably copolymerized.

The semi-aromatic crystalline polyamide resin (A1) used in the present invention is preferably a semi-aromatic polyamide resin containing 50-100 mol% of repeating units composed of hexamethylenediamine and terephthalic acid and 0-50 mol% of repeating units composed of aminoundecanoic acid or undecanoic acid amide; more preferably a semi-aromatic polyamide resin containing 50-98 mol% of repeating units composed of hexamethylenediamine and terephthalic acid and 2-50 mol% of repeating units composed of aminoundecanoic acid or undecanoic acid amide. Aromatic polyamide resin; preferably, a semi-aromatic polyamide resin containing 55-80 mol% of repeating units composed of hexamethylenediamine and terephthalic acid, and 20-45 mol% of repeating units composed of aminoundecanoic acid or undecanoic acid; particularly preferably, a semi-aromatic polyamide resin containing 60-70 mol% of repeating units composed of hexamethylenediamine and terephthalic acid, and 30-40 mol% of repeating units composed of aminoundecanoic acid or undecanoic acid. When the ratio of the repeating units composed of hexamethylenediamine and terephthalic acid in the semi-aromatic crystalline polyamide resin (A1) is less than 50 mol%, the moldability decreases along with the decrease in crystallinity, and there is a possibility that problems may arise due to the melting or deformation of the molded body in the solder reflow step due to the decrease in Tm, and the softening of the molded body in the use environment due to the decrease in Tg. On the other hand, it is more desirable to set the ratio of the repeating units composed of hexamethylenediamine and terephthalic acid in the semi-aromatic crystalline polyamide resin (A1) to 55-80 mol%, thereby controlling the crystallinity and molecular mobility of the semi-aromatic crystalline polyamide resin (A1), and appropriately improving Tm and Tg. Furthermore, by setting the ratio of the repeating units composed of hexamethylenediamine and terephthalic acid in the semi-aromatic crystalline polyamide resin (A1) to 60-70 mol%, Tm can be made 300°C-320°C and Tg can be made 70-100°C, which is not only easy to form but also more ideal in terms of the stability of the formed body in the solder reflow step or in the use environment.

As catalysts used in the production of the semi-aromatic crystalline polyamide resin (A1), phosphoric acid, phosphorous acid, hypophosphorous acid or their metal salts or ammonium salts, esters can be cited. As metal types of metal salts, specifically, potassium, sodium, magnesium, vanadium, calcium, zinc, cobalt, manganese, tin, tungsten, germanium, titanium, antimony, etc. can be cited. As esters, ethyl ester, isopropyl ester, butyl ester, hexyl ester, isodecyl ester, octadecyl ester, decyl ester, stearic acid ester, phenyl ester, etc. can be cited. In addition, from the viewpoint of improving melt retention stability, alkali compounds such as sodium hydroxide, potassium hydroxide, and magnesium hydroxide are preferably added.

The relative viscosity (RV) of the semi-aromatic crystalline polyamide resin (A1) measured in 96% concentrated sulfuric acid at 20°C is preferably 0.4-4.0, more preferably 1.0-3.0, and further preferably 1.5-2.8. As for the method of making the relative viscosity of the polyamide within a certain range, the method of adjusting the molecular weight can be listed.

The semi-aromatic crystalline polyamide resin (A1) can be prepared by adjusting the molar ratio of the amine group to the carboxyl group by polycondensation or by adding a capping agent to adjust the terminal group amount and molecular weight of the polyamide.

The time of adding the end-capping agent may be when adding the raw materials, when the polymerization starts, in the late stage of the polymerization, or when the polymerization ends. The end-capping agent is not particularly limited as long as it is a monofunctional compound reactive with the amino group or carboxyl group at the end of the polyamide, and monocarboxylic acids or monoamines, anhydrides such as phthalic anhydride, monoisocyanates, monoacid halides, monoesters, monoalcohols, etc. may be used. As for the end-capping agent, there may be mentioned, for example, 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, trimethylacetic acid, isobutyric acid, etc.; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid, etc.; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthoic acid, β-naphthoic acid, methylnaphthoic acid, phenylacetic acid, etc.; anhydrides such as maleic anhydride, phthalic anhydride, hexahydrophthalic anhydride, etc.; aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, etc.; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine, etc.; aromatic monoamines such as aniline, toluidine, diphenylamine, naphthylamine, etc., etc.

The semi-aromatic crystalline polyamide resin (A1) can be produced by a conventionally known method, for example, it can be easily synthesized by co-condensing raw material monomers. The order of the co-condensation polymerization reaction is not particularly limited, and all raw material monomers can be reacted at once, or a part of the raw material monomers can be reacted first, and then the remaining raw material monomers can be reacted. In addition, the polymerization method is not particularly limited, and it can be carried out in a continuous step from adding raw materials to preparing polymers. It is also possible to use a method in which oligomers are first prepared and then polymerized by an extruder in another step, or the oligomers are subjected to high molecular weight by solid phase polymerization. By adjusting the addition ratio of the raw material monomers, the ratio of each constituent unit in the synthesized copolymer polyamide can be controlled.

The non-crystalline polyamide resin (A2) used in the present invention preferably has a Tg of 100°C to 200°C. In addition, the Tg is more preferably 120°C to 180°C, and further preferably 120°C to 160°C. When the Tg of the non-crystalline polyamide resin (A2) is lower than the above lower limit, the rigidity of the resin may decrease depending on the use environment, which may cause problems as a product. In addition, when the Tg exceeds the above 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 or poor filling.

As an example of the non-crystalline polyamide resin (A2), there can be cited PA6T6I composed of hexamethylenediamine, terephthalic acid and isophthalic acid, PAMACMT composed of bis(3-methyl-4-aminocyclohexyl)methane and terephthalic acid, PAMACMI composed of bis(3-methyl-4-aminocyclohexyl)methane and isophthalic acid, PA12/MACMI composed of bis(3-methyl-4-aminocyclohexyl)methane, isophthalic acid and 12-aminododecanoic acid, PAMACM12 composed of bis(3-methyl-4-aminocyclohexyl)methane and dodecanedioic acid, and PAMACM14 composed of bis(3-methyl-4-aminocyclohexyl)methane and tetradecanedioic acid. These polyamides may be used alone or in combination of two or more.

The non-crystalline polyamide resin (A2) is preferably PA6T6I. PA6T6I is a non-crystalline polyamide resin with a Tg of 125°C. The mold temperature during injection molding rarely interferes with the flow of the resin, and molding processing can be easily performed, and a good appearance of the molded product can be obtained.

The relative viscosity (RV) of the non-crystalline polyamide resin (A2) used in the present invention in a 96% sulfuric acid solution at 20°C is preferably 1.4 to 3.0. Furthermore, it is more preferably 1.6 to 2.8, and further preferably 1.8 to 2.6.

The polyamide resin (A) contains 70 to 99 mass% of a semi-aromatic crystalline polyamide resin (A1) and 1 to 30 mass% of a non-crystalline polyamide resin (A2). Preferably, the semi-aromatic crystalline polyamide resin (A1) is 73 to 98 mass% and the non-crystalline polyamide resin (A2) is 2 to 27 mass%, and more preferably, the semi-aromatic polyamide resin (A1) is 75 to 97 mass% and the non-crystalline polyamide resin (A2) is 3 to 25 mass%. When the amount of the non-crystalline polyamide resin (A2) is less than the above lower limit, the appearance of the molded product deteriorates, which is not ideal. In addition, when the amount of the non-crystalline polyamide resin (A2) exceeds the upper limit, it may cause a decrease in rigidity under the use environment, which is not preferable.

The carbon fiber (B) used in the present invention has no particular restrictions as long as the fiber diameter is 3 to 10 μm and the tensile strength is 3.0 GPa or more. There is no particular restriction on the manufacturing method as long as it is a generally disclosed method. In order to improve the mechanical properties, PAN-based carbon fibers are preferred. More preferably, the carbon fiber has a strength of 4.5 GPa or more and a fiber diameter of 4.5 to 7.5 μm. There is no particular restriction on the upper limit of the strength of the carbon fiber, and it is more ideal to use a carbon fiber with a strength of 6.0 GPa or less.

For the purpose of improving the wettability of the carbon fiber (B) with the resin and improving the operability, a coupling agent or a sizing agent can also be used on the surface of the carbon fiber (B). As an example of a coupling agent, aminosilane, epoxysilane, and butylsilane can be listed. For polyamide, an aminosilane coupling agent is preferably used. In addition, for the sizing agent, a urethane or acrylic acid system is preferably used. As for the treatment amount of the above-mentioned coupling agent and sizing agent, it is preferably 0.1 to 5 parts by mass relative to 100 parts by mass of the carbon fiber, but there is no special restriction. When kneading with polyamide, the carbon fiber is preferably a chopped strand mat obtained by shearing the fiber bundle treated with the coupling agent and sizing agent into 3-8 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. When the content of carbon fiber (B) is within the above range, the molded product can exhibit high strength and excellent molded product appearance, and the number of poorly dispersed agglomerated foreign matter can be reduced, so it is more ideal.

The carbon fiber reinforced polyamide resin composition of the present invention preferably contains 0.01 to 2.0 parts by mass of an antioxidant (C). In addition, it is more preferably 0.05 to 1.5 parts by mass, and further preferably 0.1 to 1.2 parts by mass. When the amount of the antioxidant (C) is lower than the above range, there is a possibility that the desired effect of improving heat aging resistance cannot be obtained. In addition, when the amount of the antioxidant (C) exceeds the above upper limit, there is a possibility that the appearance of the molded product deteriorates due to leakage or outgassing during molding increases.

As the antioxidant (C), there can be mentioned phenolic antioxidants, phosphorus antioxidants, amine antioxidants, and sulfur 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 the copper compound (D). In addition, it is more preferably 0.01 to 0.4 parts by mass, and further preferably 0.02 to 0.3 parts by mass. Even if the copper compound (D) is not contained, the carbon fiber reinforced polyamide resin composition still has a certain degree of heat aging resistance, but in the case where heat aging resistance is particularly required, the copper compound (D) is preferably added. On the other hand, when the amount of the copper compound (D) exceeds the above upper limit, there is a possibility that the mechanical properties will be reduced.

Examples of the copper compound (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 may be blended with other components (E) within the range that does not impair the characteristics of the present invention. For example, various additives selected from stabilizers including halogenated alkali compounds, inorganic fillers, impact modifiers, sliding materials, weather resistance modifiers including carbon black, mold release agents, nucleating agents, lubricants, flame retardants, antistatic agents, pigments, dyes, etc. may be listed. The total amount of various additives may be contained (blended) in a maximum amount of 20 parts by mass relative to 100 parts by mass of the total of the polyamide resin (A) and the carbon fiber (B). In the carbon fiber reinforced polyamide resin composition of the present invention, the total amount of the essential components polyamide resin (A) and carbon fiber (B) preferably accounts for 80 mass % or more, more preferably 90 mass % or more, and further preferably 95 mass % or more.

The number of poorly dispersed agglomerated foreign bodies of the carbon fiber reinforced polyamide resin composition of the present invention is measured by the method described in the following embodiment. In order to produce a good molded product, the number of poorly dispersed agglomerated foreign bodies needs to be 15 or less. In addition, it is preferably 10 or less, more preferably 5 or less, and further preferably 1 or less. When the number of poorly dispersed agglomerated foreign bodies exceeds the above upper limit, the appearance of the molded product will deteriorate and be less ideal. If the number of poorly dispersed agglomerated foreign bodies is 5 or less, it can be determined that there are very few agglomerated foreign bodies in the molded product.

There is no particular limitation on the method for producing the carbon fiber reinforced polyamide resin composition of the present invention, and the components can be obtained by melt kneading using a conventional kneading method. There is no particular limitation on the specific kneading device, and examples thereof include a single-axis or double-axis extruder, a kneading machine, a kneading machine, etc., and a double-axis extruder is particularly ideal in terms of productivity. However, in order to disperse the components more evenly and produce a carbon fiber reinforced polyamide resin composition with no poorly dispersed agglomerated foreign bodies, when the length of the barrel from the main feed position of the kneading device to the die head is 100, and the main feed at the most upstream is taken as the starting position of kneading and is 0, it is advisable to feed the carbon fiber (B) from the barrel position 30 to 45 upstream of the standard feeding method described later, and melt-knead in more than two kneading zones, rather than the standard feeding method for fiber-based reinforcement materials such as glass fibers, that is, feeding from the barrel position 50 to 80 by side feeding and only performing melt-kneading in one kneading zone. In terms of a specific method, a semi-aromatic crystalline polyamide resin (A1), a non-crystalline polyamide resin (A2), an antioxidant (C), a copper compound (D), and other additives (E) are pre-mixed in a mixer, and then fed from a hopper into a single-axis or double-axis extruder. When at least a portion of (A1) and (A2) is molten, the carbon fiber (B) is fed into the single-axis or double-axis extruder through a feeder at the above barrel position, and after melt kneading, the mixture is ejected into a strand shape, and then cooled and sheared.

The carbon fiber reinforced polyamide resin composition of the present invention can be formed by extrusion molding, injection molding, compression molding and other conventionally known methods. The formed molded products are excellent in strength, appearance, strength retention after water absorption, and low coagulation and foreign matter properties, and can be used for various purposes. Specifically, various electrical and electronic parts such as connectors or switches, housing parts, automobile parts, sports parts, etc. can be listed, but are not limited to these.

The carbon fiber reinforced polyamide resin composition of the present invention can provide excellent strength, appearance, and strength retention after water absorption, and can suppress the number of poorly dispersed agglomerated foreign matter, thus producing a molded product that meets user needs to a high degree. [Example]

The present invention is described in more detail below by way of examples, but the present invention is not limited to these examples. In addition, the measured values recorded in the examples are measured by the following methods.

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

(2) Terminal carboxyl group concentration (CEG) The semi-aromatic polyamide resin (A1) was dissolved in a solvent of deuterated chloroform (CDCl ₃ )/hexafluoroisopropanol (HFIP) = 1/1 (volume ratio), and deuterated formic acid was added dropwise. 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 pot (manufactured by SII NanoTechnology Inc., model 170421S) and sealed with an aluminum lid (manufactured by SII NanoTechnology Inc., model 170420) to prepare a test sample. The temperature was raised from room temperature at 20°C/min using a high-sensitivity differential scanning calorimeter DSC7020 (manufactured by SII NanoTechnology Inc.) and maintained at 350°C for 3 minutes. The test sample pot was taken out and immersed in liquid nitrogen for rapid cooling. After that, the sample was taken out of the liquid nitrogen and placed at room temperature for 30 minutes, and then the temperature was raised again from room temperature at 20°C/min using a high-sensitivity differential scanning calorimeter DSC7020 (manufactured by SII NanoTechnology Inc.) and maintained at 350°C for 3 minutes. The peak temperature of the endothermic absorption due to melting during the temperature increase was set as the melting point (Tm).

(4) Glass transition temperature (Tg) 10 mg of polyamide resin (A) dried under reduced pressure at 105°C for 15 hours was weighed into an aluminum pot (manufactured by SII NanoTechnology Inc., model 170421S), and the pot was sealed with an aluminum lid (manufactured by SII NanoTechnology Inc., model 170420) to prepare a test sample. The temperature was raised from room temperature at 20°C/min using a high-sensitivity differential scanning calorimeter DSC7020 (manufactured by SII NanoTechnology Inc.), and maintained at 350°C for 3 minutes. The test sample pot was taken out and immersed in liquid nitrogen for rapid cooling. After that, the sample was taken out of the liquid nitrogen and placed at room temperature for 30 minutes. Then, the temperature was raised again from room temperature at 20°C/min using a high-sensitivity differential scanning calorimeter DSC7020 (manufactured by SII NanoTechnology Inc.) and maintained at 350°C for 3 minutes. The turning point of the baseline during the temperature increase was taken as the glass transition temperature (Tg).

(5) Flexural strength, flexural strength retention rate when absorbing water Using an injection molding machine IS-80 manufactured by Toshiba Machinery, the cylinder temperature was set to the melting point of the semi-aromatic crystalline polyamide resin (A1) + 20°C, and the mold temperature was set to 140°C. In accordance with ISO-178, test pieces for evaluation were made, and the results of the physical property evaluation were used as the flexural strength when absolutely dry. In addition, after the test pieces were placed in an environment of 80°C and 95%RH (relative humidity) for 1000 hours, the results of the flexural physical property evaluation in accordance with ISO-178 were used as the flexural strength when saturated with water. In addition, the flexural strength retention rate when absorbing water was obtained by the following formula. Bending strength maintenance rate when absorbing water (%) = (bending strength when saturated with water/bending strength when absolutely dry) × 100

(6) Surface appearance of molded products A Toshiba Machinery IS-80 injection molding machine was used. 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 the injection speed was set to 40%. Test pieces with a length of 100 mm, a width of 100 mm, and a thickness of 2 mm were produced by injection molding. The appearance of the test pieces was visually evaluated. Those without fiber-like appearance were judged as ○, and those with fiber-like appearance were judged as ×.

(7) Number of poorly dispersed agglomerated foreign matter in molded products A Toshiba Machinery injection molding machine IS-80 was used. 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 holding pressure was set to 25%, the injection holding time was set to 10 seconds, and the cooling time was set to 12 seconds. Test specimens with a length of 100 mm, a width of 100 mm, and a thickness of 1 mm were produced by injection molding. Ten test specimens were used to count the number of poorly dispersed agglomerated foreign matter. The number of poorly dispersed agglomerated foreign matter is the number per 10 test specimens. In addition, if there is a case where poorly dispersed agglomerated foreign matter is mixed in, it can be seen floating on the surface of the molded product because the size is 0.5 mm or more, so it can be visually confirmed.

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

[Table 1] Semi-aromatic crystalline polyamide resin A1-1 A1-2 A1-3 Constituent monomer Terephthalic acid (mol%) 65.1 64.8 64.9 1,6-Hexamethylenediamine (mol%) 65.1 64.8 64.9 11-aminoundecanoic acid (mol%) 34.9 35.2 35.1 Relative viscosity (RV) 2.1 2.1 2.1 Melting point (Tm) (℃) 314 315 315 Terminal carboxyl concentration (CEG) (eq/ton) 140 30 70

>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 modifier, and 16.20 kg of ion exchange water were added to a 50-liter autoclave, pressurized from normal pressure to 0.05 MPa with _N2 , and released to return to normal pressure. This operation was performed 3 times, and after _N2 replacement, it was uniformly dissolved at 135°C and 0.3 MPa under stirring. After that, the solution was continuously supplied by a liquid delivery pump, and the temperature was raised to 240°C in the heating pipe, and heat was applied for 1 hour. The reaction mixture was then supplied to a pressure reactor, heated to 290°C, and the pressure in the reactor was maintained at 3 MPa to allow a portion of the water to be distilled out, thereby obtaining a low-order condensate. The low-order condensate was then directly supplied to a two-screw extruder (screw diameter 37 mm, L/D = 60) while being maintained in a molten state, and polymerized in a molten state while the resin temperature reached 335°C and water was discharged from three ports, thereby obtaining a semi-aromatic crystalline polyamide resin (A1-1). The obtained semi-aromatic crystalline polyamide resin (A1-1) is composed of 65.1 mol% of constituent units composed of 1,6-hexamethylenediamine and terephthalic acid, and 34.9 mol% of constituent units composed of 11-aminoundecanoic acid. The relative viscosity is 2.1, the melting point is 314°C, and the AEG (terminal amine concentration) analyzed by ¹ H-NMR is 20 eq/ton, and the CEG is 140 eq/ton.

>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, the sodium hypophosphite as a catalyst was changed to 9 g, the acetic acid as a capping agent was changed to 330 g and the ion exchange water was changed 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) is composed of 64.8 mol% of constituent units composed of 1,6-hexamethylenediamine and terephthalic acid, and 35.2 mol% of constituent units composed of 11-aminoundecanoic acid. The relative viscosity is 2.1, the melting point is 315°C, and the AEG=30eq/ton and CEG=30eq/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, the sodium hypophosphite as a catalyst was changed to 9 g, the acetic acid as a capping agent was changed to 255 g and the ion exchange water was changed 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) is composed of 64.9 mol% of constituent units composed of 1,6-hexamethylenediamine and terephthalic acid, and 35.1 mol% of constituent units composed of 11-aminoundecanoic acid. The relative viscosity is 2.1, the melting point is 315°C, and the AEG is 30 eq/ton and the CEG is 70 eq/ton as analyzed by ¹ H-NMR.

The following raw materials are used in this embodiment and comparative example. Semi-aromatic crystalline polyamide resin (A1-1): Semi-aromatic crystalline polyamide resin prepared according to the above-mentioned synthesis example 1 Semi-aromatic crystalline polyamide resin (A1-2): Semi-aromatic crystalline polyamide resin prepared according to the above-mentioned synthesis example 2 Semi-aromatic crystalline polyamide resin (A1-3): Semi-aromatic crystalline polyamide resin prepared according to the above-mentioned synthesis example 3 Non-crystalline polyamide resin (A2-1): PA6T6I, "Grivory (R) G21" manufactured by EMS, Tg125℃ Non-crystalline polyamide resin (A2-2): PA12/MACMI, "Grilamide (R) TR55", Tg160℃ Polyamide resin (A3): PAMXD6 (poly(m-xylene hexamethylenediamide), "Toyobo Nylon(R) T600" manufactured by Toyobo Co., Ltd., Tm237℃, Tg80℃ Carbon fiber (B-1): "CFUW-LC-HS" manufactured by Nippon Polymer Industries, Ltd., fiber diameter 5.5μm, shear length 6mm, tensile strength 5.5GPa Carbon fiber (B-2): "CFUW-MC" manufactured by Nippon Polymer Industries, Ltd., fiber diameter 7μm, shear length 6mm, tensile strength 4.9GPa Antioxidant (C): "Irganox(R) 1010", pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] Copper compound (D): copper (II) bromide Mold release agent (E): magnesium stearate Glass fiber (F): glass fiber "T-275H" manufactured by Nippon Electric Glass Co., Ltd., fiber diameter 11μm

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

[Table 2]

As can be seen from Table 2, the carbon fiber reinforced polyamide resin composition of Examples 1 to 10 is a blend of a semi-aromatic crystalline polyamide resin (A1) and a non-crystalline polyamide resin (A2), and the supply position of the carbon fiber (B) in the manufacturing step is adjusted, thereby improving the strength retention rate after saturated water absorption, the surface appearance of the molded product, and the carbon fiber poorly dispersed agglomerates. In addition, in Examples 9 and 10, the number of poorly dispersed agglomerates is 12 and 5, respectively. By changing the CEG of the semi-aromatic crystalline polyamide resin (A1), the number of poorly dispersed agglomerates can be suppressed as in Example 1.

>Comparative Examples 1 and 2> Ingredients other than carbon fiber (B) were dry-blended at the blending ratio shown in Table 3, and melt-mixed using an exhaust two-screw extruder "STS35mm" (barrel 12-block structure) manufactured by Coperion Corporation, with the barrel temperature set to Tm+15°C of the semi-aromatic crystalline polyamide resin (A1) and the screw speed set to 250rpm. Then, carbon fiber (B) was fed by side feeding at a position of 67 from the upstream side when the barrel length from the main feeding position to the die head was 100, and melt-mixed. The strands extruded from the two-screw extruder were rapidly cooled and pelletized using a strand shear. The pellets were dried at 100°C for 12 hours and then molded into various test specimens using an injection molding machine (IS-80 manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of Tm of the semi-aromatic crystalline polyamide resin (A1) + 20°C and a mold temperature of 140°C for evaluation.

>Comparative Examples 3~5> Ingredients other than carbon fiber (B) were dry-blended according to the blending ratio shown in Table 3, and melt-mixed using an exhaust two-screw extruder "STS35mm" (barrel 12-block structure) manufactured by Coperion Corporation, with the barrel temperature set to Tm+15°C of the semi-aromatic crystalline polyamide resin (A1) and the screw speed set to 250rpm. Then, carbon fiber (B) was fed to the position 42 from the upstream side by side feeding, and melt-mixed when the barrel length from the main feeding position to the die head was 100. The strands extruded from the two-screw extruder were rapidly cooled and pelletized using a strand shear. The pellets were dried at 100°C for 12 hours and then molded into various test specimens using an injection molding machine (IS-80 manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of Tm of the semi-aromatic crystalline polyamide resin (A1) + 20°C and a mold temperature of 140°C for evaluation.

>Reference Examples 1, 2> Ingredients other than glass fiber (F) were dry-blended according to the blending ratio shown in Table 3, and melt-mixed using an exhaust double-screw extruder "STS35mm" (barrel 12-block structure) manufactured by Coperion Corporation, with the barrel temperature set to Tm+15°C of the semi-aromatic crystalline polyamide resin (A1) and the screw speed set to 250rpm. Then, glass fiber (F) was fed by side feeding at a position of 67 (Reference Example 1) or 42 (Reference Example 2) from the upstream side when the barrel length from the main feeding position to the die head was 100, and melt-mixed. The strands extruded from the two-axis extruder were rapidly cooled and made into pellets using a strand shear. The pellets were dried at 100°C for 12 hours and then formed into various test specimens by an injection molding machine (IS-80, manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of Tm+20°C of the semi-aromatic crystalline polyamide resin (A1) and a mold temperature of 140°C for evaluation.

[Table 3] Comparison Example 1 Comparison Example 2 Comparison Example 3 Comparison Example 4 Comparison Example 5 Reference Example 1 Reference Example 2 Composition A1-1 Quality 72 63 70 60 54 65 65 A2-1 Quality 8 A2-2 Quality 7 A3 Quality 6 B-1 Quality 20 40 40 B-2 Quality 30 30 C Quality 0.2 0.2 0.2 0.2 0.2 0.2 0.2 D Quality 0.02 0.02 0.02 0.02 0.02 0.02 0.02 E Quality 0.3 0.3 0.3 0.3 0.3 0.3 0.3 F Quality 35 35 Supply position of carbon fiber (B) during the extrusion step of manufacturing 67 67 42 42 42 The feeding position of glass fiber (F) in the manufacturing extrusion step 67 42 Bending strength when absolutely dry (MPa) 382 359 357 488 521 283 244 Bending strength when fully absorbed water (MPa) 343 328 318 435 377 259 226 Strength retention rate after water absorption (%) 90 91 89 89 72 92 93 Surface appearance ○ ○ × × ○ ○ ○ Poorly dispersed aggregated foreign matter number (pieces/10 tablets) 39 59 0 0 0 0 0

In Comparative Examples 1 and 2, since the feeding position of the carbon fiber (B) in the manufacturing step is inappropriate, a large amount of poorly dispersed carbon fiber agglomerates are generated, and the carbon fiber reinforced polyamide resin composition is not satisfactory. In Comparative Examples 3 and 4, since the non-crystalline polyamide resin (A2) is not mixed, the surface appearance deteriorates, and the carbon fiber reinforced polyamide resin composition is not satisfactory. In Comparative Example 5, since the non-crystalline polyamide resin (A2) is changed to the polyamide resin (A3), the strength retention rate after saturated water absorption is reduced, and the carbon fiber reinforced polyamide resin composition is not satisfactory.

As can be seen from Reference Examples 1 and 2, when glass fiber (F) is used, no matter which of the two supply positions is used, poorly dispersed agglomerates will not be generated. [Industrial Applicability]

The carbon fiber reinforced polyamide resin composition of the present invention is excellent in strength, appearance, strength retention rate after water absorption, and the number of poorly dispersed foreign matter aggregation. The molded product using the carbon fiber reinforced polyamide resin composition can be appropriately used as a housing for electronic and electrical parts, vehicle parts used for automobile interior and exterior, and sports and leisure parts.

without

Claims (5)

A carbon fiber reinforced polyamide resin composition comprises: 50-90 parts by weight of polyamide resin (A) and 10-50 parts by weight of carbon fiber (B); the polyamide resin (A) comprises 70-99% by weight of a semi-aromatic crystalline polyamide resin (A1) containing terephthalic acid as a component and 1-30% by weight of a non-crystalline polyamide resin (A2); the semi-aromatic crystalline polyamide resin (A1) comprises a carbon fiber having a carbon number of 6 to A semi-aromatic polyamide resin comprising 50 to 100 mol% of repeating units composed of diamine with 12 moles and terephthalic acid, and 0 to 50 mol% of repeating units composed of aminocarboxylic acid or lactam with a carbon number of 10 or more, wherein the semi-aromatic crystalline polyamide resin (A1) has a terminal carboxyl group concentration (CEG) of 40 eq/ton or more, and the non-crystalline polyamide resin (A2) is selected from hexamethylenediamine, terephthalic acid and isophthalic acid. PA6T6I, PAMACMT composed of bis(3-methyl-4-aminocyclohexyl)methane and terephthalic acid, PAMACMI composed of bis(3-methyl-4-aminocyclohexyl)methane and isophthalic acid, PA12/MACMI composed of bis(3-methyl-4-aminocyclohexyl)methane, isophthalic acid and 12-aminododecanoic acid, and PA12/MACMI composed of bis(3-methyl-4-aminocyclohexyl)methane and dodecanediol. The polyamide PAMACM12 composed of bis(3-methyl-4-aminocyclohexyl)methane and tetradecanedioic acid and PAMACM14 composed of bis(3-methyl-4-aminocyclohexyl)methane and tetradecanedioic acid can be used alone or in combination of two or more. The number of poorly dispersed agglomerated foreign particles in a flat plate test piece with 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 less than 10. The carbon fiber reinforced polyamide resin composition of claim 1 further contains an antioxidant (C) in an amount of 0.01 to 2.0 parts by weight relative to 100 parts by weight of the total of the polyamide resin (A) and the carbon fiber (B). The carbon fiber reinforced polyamide resin composition of claim 1 further contains a copper compound (D) in an amount of 0.01 to 0.5 parts by mass relative to 100 parts by mass of the total of the polyamide resin (A) and the carbon fiber (B). The carbon fiber reinforced polyamide resin composition of claim 2 further contains a copper compound (D) in an amount of 0.01 to 0.5 parts by mass relative to 100 parts by mass of the total of the polyamide resin (A) and the carbon fiber (B). A molded article is composed of the carbon fiber reinforced polyamide resin composition as described in any one of claims 1 to 4.