JP2014210849A - Polyamide resin composition comprising carbon nanofiber, method of producing the same, and molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin composition having excellent fatigue characteristics, mechanical characteristics, and conductivity.SOLUTION: A polyamide resin composition comprises (A) polyamide resin, (B) carbon nanofiber, and (C) fibrous reinforcing material. An aspect ratio (L/D) of the (B) carbon nanofiber in the polyamide resin composition is 40 or more.

Description

  The present invention relates to a polyamide resin composition containing carbon nanofibers, a method for producing the same, and a molded body.

  Polyamide resins are used in various industrial fields by taking advantage of their excellent mechanical properties and heat resistance. In particular, a so-called reinforced polyamide resin in which mechanical properties such as strength and rigidity are further improved by reinforcement with a fibrous reinforcing material such as glass fiber is preferably used. In addition, a polyamide resin to which both a fibrous reinforcing material such as glass fiber and carbon nanofibers are added is expected as a high-performance composite material capable of increasing conductivity, thermal conductivity, and strength.

  In such a composite material, for the purpose of improving mechanical properties by adding a fibrous reinforcing material such as glass fiber and improving conductivity by adding carbon nanofiber, the fibrous reinforcing material such as glass fiber and carbon nanofiber are added. A combination of fibers is being studied. For example, the technique regarding the resin composition which added glass fiber and carbon nanofiber to the polyamide resin is disclosed (for example, patent documents 1).

Japanese Patent Laid-Open No. 2005-171201

  However, the technique disclosed in Patent Document 1 has insufficient long-term fatigue characteristics. Furthermore, further improvement in mechanical strength is demanded. This invention is made | formed in view of such a situation, Comprising: It aims at providing the polyamide resin composition which is excellent in a fatigue characteristic, a mechanical characteristic, and electroconductivity.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by blending a carbon nanofiber having a specific aspect ratio (L / D) and a fibrous reinforcing material into a polyamide resin. The invention has been completed.

That is, the present invention is as follows.
[1]
A polyamide resin composition comprising (A) a polyamide resin, (B) carbon nanofibers, and (C) a fibrous reinforcing material,
The polyamide resin composition whose (B) carbon nanofiber aspect ratio (L / D) in the said polyamide resin composition is 40 or more.
[2]
When the polyamide resin composition is molded into pellets, the pellets are cut into a thickness of 2 μm using a microtome, and observed with an optical microscope (400 ×) at a viewing angle of 200 μm × 200 μm. The polyamide resin composition according to [1], wherein fiber aggregates are observed, and the major axis of the aggregates is less than 10 μm.
[3]
(B) The ratio of the peak area (D) of the band between 1335 and 1365 cm-1 to the peak area (G) of the band between 1565 and 1600 cm-1 of the Raman scattering spectrum of the carbon nanofiber (D / G ) Is 1.0 or more, the polyamide resin composition according to [1] or [2].
[4]
The polyamide resin composition according to any one of [1] to [3], wherein the content of the carbon nanofiber (B) in the polyamide resin composition is 0.1 to 15% by mass.
[5]
The polyamide resin composition according to any one of [1] to [4], wherein the content of the (C) fibrous reinforcing material in the polyamide resin composition is 10 to 50% by mass.
[6]
The polyamide resin composition according to any one of [1] to [5], wherein the (A) polyamide resin is polyamide 66.
[7]
(A) the polyamide resin; (D) the (B) carbon nanofibers and (E) at least one selected from the group consisting of a modified rosin, a styrene resin, an olefin resin, and an acrylic resin. Any one of [1] to [6] obtained by kneading the carbon nanofiber granule satisfying the relationship of the following formulas (1) and (2); and the (C) fibrous reinforcing material 2. The polyamide resin composition according to item 1.

0.01 ≦ P1 ≦ 1 (1)
0 <P1 / P2 ≦ 3.3 (2)

P1: Maximum pore volume (cm ³ / g) at a pore diameter of 2,500 nm to 100,000 nm in pore distribution data measured with a mercury porosimeter
P2: Maximum pore volume (cm ³ / g) at a pore diameter of 6 nm or more and less than 2,500 nm in pore distribution data measured with a mercury porosimeter
[8]
(A) the polyamide resin;
(D) the carbon nanofiber (B) and (E) at least one selected from the group consisting of a modified rosin, a styrene resin, an olefin resin, and an acrylic acid resin, and the following formula (1) And a carbon nanofiber granule satisfying the relationship of formula (2),
(C) fibrous reinforcing material;
The manufacturing method of the polyamide resin composition of any one of [1]-[6] including the process of kneading | mixing.

0.01 ≦ P1 ≦ 1 (1)
0 <P1 / P2 ≦ 3.3 (2)

P1: Maximum pore volume (cm ³ / g) at a pore diameter of 2,500 nm to 100,000 nm in pore distribution data measured with a mercury porosimeter
P2: Maximum pore volume (cm ³ / g) at a pore diameter of 6 nm or more and less than 2,500 nm in pore distribution data measured with a mercury porosimeter
[9]
(D) The method for producing a polyamide resin composition according to [8], wherein the carbon nanofiber granule further satisfies the relationship of the following formula (3).

0.75 ≦ Q2 / (Q1 + Q2) <1 (3)

Q1: Integrated pore volume (cm ³ / g) at a pore diameter of 2,500 nm to 100,000 nm in pore distribution data measured with a mercury polysimeter
Q2: Accumulated void volume (cm ³ / g) at a pore diameter of 6 nm or more and less than 2,500 nm in pore distribution data measured with a mercury polysimeter
[10]
(D) The carbon nanofiber granule having a particle size that passes through a sieve having a nominal opening defined by JIS Z8801-1 in excess of 0.3 mm and not more than 4.75 mm in the total amount of the carbon nanofiber granule. The manufacturing method of the polyamide resin composition of Claim 8 or 9 whose content rate is 90 mass% or more.
[11]
The molded object containing the polyamide resin composition of any one of [1]-[7].

  ADVANTAGE OF THE INVENTION According to this invention, the polyamide resin composition which is excellent in a fatigue characteristic, a mechanical characteristic, and electroconductivity can be provided.

(D) It is a conceptual diagram for demonstrating an example of a carbon nanofiber granulation body. (D) It is a conceptual diagram for demonstrating another example of a carbon nanofiber granulation body.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented with appropriate modifications within the scope of the gist thereof.

  The polyamide resin composition of this embodiment is a polyamide resin composition comprising (A) a polyamide resin, (B) carbon nanofibers, and (C) a fibrous reinforcing material, B) It is a polyamide resin composition whose aspect ratio (L / D) of carbon nanofiber is 40 or more.

[(A) Polyamide component]
In the present embodiment, “(A) polyamide resin” means a polymer having an amide bond (—NHCO—) in the main chain. The polyamide is not particularly limited. For example, polyamide obtained by ring-opening polymerization of lactam, polyamide obtained by self-condensation of ω-aminocarboxylic acid, polyamide obtained by condensation polymerization of diamine and dicarboxylic acid, and these polyamides And a copolymer obtained by copolymerization of two or more types of monomers. These polyamides may be used alone or in combination of two or more.

Hereinafter, the raw material of the polyamide resin will be described.
First, the polyamide obtained by ring-opening polymerization of lactam will be described. The lactam as a monomer which is a constituent component of polyamide is not particularly limited, and examples thereof include pyrrolidone, caprolactam, undecaractam, dodecaractam and the like. A lactam may be used individually by 1 type and may use 2 or more types together.

  Next, the polyamide obtained by self-condensation of ω-aminocarboxylic acid will be described. The raw material ω-aminocarboxylic acid is not particularly limited, and examples thereof include ω-amino fatty acids that are ring-opening compounds of the above lactams with water. The ω-aminocarboxylic acid may be used alone or in combination of two or more.

  Subsequently, the polyamide obtained by condensing diamine and dicarboxylic acid will be described. The diamine monomer is not particularly limited, and examples thereof include linear aliphatic diamines such as tetradiamine, hexamethylenediamine, pentamethylenediamine, nonanediamine, decanediamine, and dodecanediamine; 2-methylpentanediamine, 2- Examples include branched aliphatic diamines such as ethylhexamethylenediamine; aromatic diamines such as p-phenylenediamine and m-phenylenediamine; and alicyclic diamines such as cyclohexanediamine, cyclopentanediamine, and cyclooctanediamine.

  The dicarboxylic acid monomer is not particularly limited, and examples thereof include malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, and 2,2-dimethylglutar. Aliphatic dicarboxylic acids such as acid, 3,3-diethylsuccinic acid, azelaic acid, sebacic acid and suberic acid; alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; Acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, diphen Acid, diphenylmethane-4,4′-dicarboxylic acid, diphenylsulfone-4,4′-dicarboxylic acid 4,4'-biphenyl dicarboxylic acid, MXD (m-xylylenediamine), etc. PXD units derived from an aromatic dicarboxylic acid (parameter xylylenediamine), etc. (unit) and the like. These may be used individually by 1 type and may use 2 or more types together.

  Specific examples of the polyamide are not particularly limited. For example, polyamide 4 (polyα-pyrrolidone), polyamide 6 (polycaproamide), polyamide 11 (polyundecanamide), polyamide 12 (polydodecanamide), polyamide 46 (polytetramethylene adipamide), polyamide 56 (polypentamethylene adipamide), polyamide 66 (polyhexamethylene adipamide), polyamide 610 (polyhexamethylene sebacamide), polyamide 612 (polyhexamethylene dodeca) Amide), polyamide 116 (polyundecamethylene adipamide), polyamide TMHT (trimethylhexamethylene terephthalamide), polyamide 6T (polyhexamethylene terephthalamide), polyamide 2Me-5T (poly-2-methylbenzene) Tamethylene terephthalamide), polyamide 9T (polynonamethylene terephthalamide), 2Me-8T (poly 2-methyloctamethylene terephthalamide), polyamide 6I (polyhexamethylene isophthalamide), polyamide 6C (polyhexamethylenecyclohexanedicarboxamide) , Polyamide 2Me-5C (poly-2-methylpentamethylenecyclohexanedicarboxamide), polyamide 9C (polynonamethylenecyclohexanedicarboxamide), 2Me-8C (poly-2-methyloctamethylenecyclohexanedicarboxamide), polyamide PACM12 (polybis (4- Aminocyclohexyl) methane dodecamide), polyamide dimethyl PACM12 (polybis (3-methyl-aminocyclohexyl) methane dodecamide) , Polyamide MXD6 (polymetaxylylene adipamide), polyamide 10T (polydecamethylene terephthalamide), polyamide 11T (polyundecamethylene terephthalamide), polyamide 12T (polydodecamethylene terephthalamide), polyamide 10C (polydecamethylenecyclohexane) Dicarboxamide), polyamide 11C (polyundecamethylenecyclohexanedicarboxamide), polyamide 12C (polydodecamethylenecyclohexanedicarboxamide) and the like.

  Among these, as the polyamide resin, polyamide 6 (polycaproamide), polyamide 66 (polyhexamethylene adipamide), polyamide 610 (polyhexamethylene sebacamide), polyamide 612 (polyhexamethylene dodecamide), polyamide 6T (polyhexamethylene terephthalamide), polyamide 2Me-5T (poly-2-methylpentamethylene terephthalamide), polyamide 9T (polynonamethylene terephthalamide), 2Me-8T (poly-2-methyloctamethylene terephthalamide), polyamide 6I (Polyhexamethylene isophthalamide), polyamide 6C (polyhexamethylenecyclohexanedicarboxamide), polyamide 2Me-5C (poly-2-methylpentamethylenecyclohexanedicarboxamide) , Polyamide 9C (poly nonamethylene cyclohexane dicarboxamide), 2Me-8C (poly 2-methyl-octamethylene cyclohexane dicarboxamide), polyamide 6I (polyhexamethylene isophthalamide) are preferred.

  The polyamide resin may be a polyamide copolymer obtained by copolymerizing two or more units constituting the above-described polyamide.

  The polyamide copolymer is not particularly limited, and examples thereof include polyamide 66 / 6I, PA66 / 6T, PA6T / 2Me-5T, PA9T / 2Me-8T, PA6C / 2Me-5C, PA9C / 2Me-8C, and the like. Examples include coalescence.

  Among these, the polyamide component is preferably polyamide 6, polyamide 66, polyamide 66/6, polyamide 66 / 6I, polyamide 6C / 2Me-5C, polyamide 2Me-5C, and polyamide 6, polyamide 66, polyamide 66/6, polyamide 66 / 6I is more preferable, and polyamide 66 is more preferable.

  As a raw material for polyamide, an end-capping agent can be further added for molecular weight adjustment and improvement of hot water resistance. For example, when polymerizing polyamide, a known end-capping agent can be further added.

  The end-capping agent is not particularly limited, and examples thereof include monoamines, diamines, monocarboxylic acids, dicarboxylic acids, acid anhydrides such as phthalic anhydride, monoisocyanates, monoacid halides, monoesters, and monoalcohols. Can be mentioned. Among these, monocarboxylic acids and monoamines are preferable from the viewpoint of production cost. These end capping agents may be used alone or in combination of two or more.

  The monoamine is not particularly limited, and examples thereof include aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine. Alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine and naphthylamine, and any mixtures thereof. Among these, butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline are preferable from the viewpoints of reactivity, boiling point, stability of the sealing end, price, and the like. These may be used alone or in combination of two or more.

  As said diamine, the illustration of the diamine mentioned above as a raw material of polyamide can also be cited as it is. These may be used alone or in combination of two or more.

  The monocarboxylic acid is not particularly limited. For example, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecyl acid, myristic acid, palmitic acid, stearic acid, pivalic acid, isobutyl. Aliphatic monocarboxylic acids such as acids; Alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; Aromatics such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid A monocarboxylic acid etc. are mentioned. These may be used alone or in combination of two or more.

  The acid anhydride is not particularly limited, and examples thereof include acid anhydrides such as phthalic anhydride, maleic anhydride, benzoic anhydride, acetic anhydride, and hexahydrophthalic anhydride. These may be used individually by 1 type and may use 2 or more types together.

  The monoisocyanate is not particularly limited, and examples thereof include phenyl isocyanate, tolyl isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, butyl isocyanate, and naphthyl isocyanate. These may be used individually by 1 type and may use 2 or more types together.

  The monoacid halide is not particularly limited, and examples thereof include benzoic acid, diphenylmethane carboxylic acid, diphenyl sulfone carboxylic acid, diphenyl sulfoxide carboxylic acid, diphenyl sulfide carboxylic acid, diphenyl ether carboxylic acid, benzophenone carboxylic acid, biphenyl carboxylic acid, Examples include halogen-substituted monocarboxylic acids such as α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, and monocarboxylic acids such as anthracenecarboxylic acid. These may be used individually by 1 type and may use 2 or more types together.

  The monoester is not particularly limited, and examples thereof include glycerin monopalmitate, glycerin monostearate, glycerin monobehenate, glycerin monomontanate, pentaerythritol monopalmitate, pentaerythritol monostearate, pentaerythritol monobehethe. Nate, pentaerythritol monomontanate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monobehenate, sorbitan monomontanate, sorbitan dimontanate, sorbitan trimontanate, sorbitol monopalmitate, sorbitol monostearate, sorbitol monobetal Examples include henate, sorbitol tribehenate, sorbitol monomontanate, and sorbitol dimontanate. These may be used individually by 1 type and may use 2 or more types together.

  The monoalcohol is not particularly limited, and for example, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, heptanol Decanol, octadecanol, nonadecanol, eicosanol, docosanol, tricosanol, tetracosanol, hexacosanol, heptacosanol, octacosanol, triacontanol (above, linear, branched), oleyl alcohol, behenyl alcohol, phenol, cresol ( o-isomer, m-isomer, p-isomer), biphenol (o-isomer, m-isomer, p-isomer), 1-naphthol, 2-naphthol and the like. These may be used individually by 1 type and may use 2 or more types together.

  It does not specifically limit as a manufacturing method of a polyamide polymer, A well-known method can be used. For example, a method in which an aqueous solution or a suspension of water in a mixture of adipic acid, isophthalic acid, sebacic acid, hexamethylenediamine, and / or other components is heated and polymerized while maintaining a molten state (thermal melt polymerization method) ); Method of increasing the degree of polymerization of the polyamide copolymer obtained by the hot melt polymerization method while maintaining the solid state at a temperature below the melting point (hot melt polymerization / solid phase polymerization method); adipic acid, isophthalic acid, sebacine A method in which an aqueous solution or a suspension of water of a mixture of acid, hexamethylenediamine, and / or other components is heated, and the precipitated prepolymer is melted again with an extruder such as a kneader to increase the degree of polymerization ( Prepolymer / extrusion polymerization method): Add a solution of adipic acid, isophthalic acid, sebacic acid, hexamethylenediamine, and / or a mixture of other components with an aqueous solution or water suspension. A method in which the degree of polymerization is increased while maintaining the solid state at a temperature below the melting point of the polyamide (prepolymer / solid phase polymerization method); adipic acid, isophthalic acid, sebacic acid, hexamethylenediamine, and Examples thereof include a method of polymerizing a mixture with other components, a solid salt or a polycondensate (solid phase polymerization method) while maintaining a solid state.

  The polymerization form is not particularly limited, and may be a batch type or a continuous type. The polymerization apparatus is not particularly limited, and a known apparatus such as an autoclave type reactor, a tumbler type reactor, an extruder type reactor such as a kneader, or the like can be used.

[(B) Carbon nanofiber]
In the polyamide resin composition of this embodiment, the aspect ratio (L / D) of the carbon nanofibers contained is 40 or more. The aspect ratio (L / D) is the ratio (L / D) of the average fiber length (L) of the carbon nanofibers to the average fiber diameter (D) of the carbon nanofibers. Moreover, the aspect ratio here is an aspect ratio of (B) carbon nanofiber contained in the polyamide resin composition, and before kneading with (A) polyamide resin or (C) fibrous reinforcing material. It is not the aspect ratio of carbon nanofibers.

  In addition, the average fiber length here refers to a weight average length. These average fiber diameter and average fiber length can be determined according to the following method. First, the resin composition to be measured is charged into a solvent, and a dispersion solution of the dispersion solution or a residue in which only the resin is thermally decomposed is prepared. The dispersion solution is filtered and dried to obtain a measurement sample. This measurement sample can be obtained by observing with a scanning electron microscope or a transmission electron microscope and statistically analyzing the observed image.

  When the aspect ratio of (B) carbon nanofibers in the polyamide resin composition is less than 40, fatigue properties (tensile creep) and electrical conductivity at high temperatures are insufficient. As a result of intensive studies by the present inventors on conventional polyamide resin compositions containing carbon nanofibers, the aspect ratio of the carbon nanofibers in the resin composition is low, so that desired physical properties cannot be obtained. I thought that. Based on this assumption, the present inventors examined not only the carbon nanofibers as the additive material but also the carbon nanofibers present in the polyamide resin composition in detail. As a result, surprisingly, it has been found that by setting the aspect ratio of the carbon nanofibers present in the polyamide resin composition to 40 or more, the physical properties as the polyamide resin composition are greatly improved. It came to implement | achieve the polyamide resin composition of this embodiment.

  (B) Although the minimum of the aspect-ratio of carbon nanofiber should just be 40 or more, Preferably it is 42 or more, More preferably, it is 45 or more. (B) The upper limit of the aspect ratio of the carbon nanofiber is preferably 1000 or less, more preferably 800 or less, and even more preferably 500 or less. By setting the upper limit of the aspect ratio to the above value, the dispersion state of (B) carbon nanofibers in the polyamide resin composition is further dispersed.

  The aspect ratio here tends to increase by blending (A) a polyamide resin, (C) a fibrous reinforcing material, and a granulated body of (D) carbon nanofibers described later. Also, by reducing the kneading shear force during melt processing and reducing the kneading history, the aspect ratio tends to increase and the dispersibility of (B) carbon nanofibers in the polyamide resin composition Tend to decline. Also, increasing the shearing force during melt processing and increasing the kneading history tend to reduce the aspect ratio and improve the dispersibility of (B) carbon nanofibers in the polyamide resin composition. Tend to. In the polyamide resin composition of the present embodiment, it is possible to achieve both a high aspect ratio and dispersibility at a level that could not be achieved conventionally by being based on such guidelines and the like.

  Regarding the dispersibility (dispersion state) of the carbon nanofibers in the polyamide resin composition, 10 pellets molded from the polyamide resin composition were cut out one by one with a thickness of 2 μm using a microtome, and an optical microscope ( (400 times) at a viewing angle of 200 μm × 200 μm, the long axis of the carbon nanofiber aggregates observed in the observation region of the optical microscope is preferably less than 10 μm. When the carbon nanofibers in the polyamide resin composition take such a dispersed state, the tensile strength and fatigue characteristics (tensile creep) at high temperatures can be improved as a composite material of the polyamide resin and the carbon nanofibers. In addition, the aggregate of carbon nanofibers here refers to an aggregate of a plurality of carbon nanofibers.

  (B) The carbon nanofiber may be either a single layer or a multilayer carbon nanofiber of two or more layers. The layer structure of carbon nanofibers can be selected according to the purpose. From the viewpoint of production cost and dispersibility with respect to the resin, a carbon nanofiber having two or more layers is preferable. Since the carbon nanofibers having two or more layers have good dispersibility in the resin, the strength and the like can be further improved.

  The method for producing the carbon nanofiber is not particularly limited, and any conventionally known method such as a vapor phase growth method using a catalyst, an arc discharge method, a laser evaporation method, and a HiPco method (High-pressure carbon monoxide process). A manufacturing method may be used.

  A method for producing multi-layered carbon nanofibers by vapor deposition is shown below. Specifically, an organic transition metal compound such as ferrocene or nickel sen is used as a metal catalyst, and an organic compound such as hydrocarbon is chemically pyrolyzed by a CVD method to produce a fiber structure (hereinafter referred to as “non-graphitized carbon nanofiber”). And the like, a method of generating carbon nanofibers in a floating state, a method of growing carbon nanofibers on the reaction furnace wall, and the like. Alternatively, carbon nanofibers can be obtained by bringing metal-containing particles previously supported on a refractory support such as alumina or carbon into contact with a carbon-containing compound at a high temperature.

  An example of a method for producing carbon nanofibers from an organic compound will be described. Carbon compounds such as hydrocarbons such as benzene, toluene and xylene, and alcohols such as carbon monoxide and ethanol are used as the organic compound as a raw material for the carbon nanofibers. Among these, it is preferable to use two or more carbon compounds having different decomposition temperatures as the carbon source. In addition, at least 2 or more types of carbon compounds are not only cases where two or more types of organic compounds as raw materials are used, but also cases where one type of organic compound as a raw material is used. In the process of synthesizing carbon nanofibers, for example, a case where a reaction such as hydrogen dealkylation of toluene or xylene occurs and two or more carbon compounds having different decomposition temperatures are generated by the subsequent thermal decomposition reaction is included. . Inert gas such as argon, helium, xenon and hydrogen can be used as the atmospheric gas for pyrolysis, and transition metals such as iron, cobalt and molybdenum or transition metals such as ferrocene and metal acetate are used as catalysts. A mixture of the compound and sulfur or a sulfur compound such as thiophene or iron sulfide can be used.

  Using a commonly used CVD method such as hydrocarbon, the mixture of hydrocarbon and catalyst as raw materials is evaporated, hydrogen gas or the like is introduced into the reactor as a carrier gas, and heated at a temperature of 400 to 1300 ° C. By decomposing, intermediate carbon nanofibers are produced. Through such pyrolysis, sparse carbon nanofibers are formed in which fibers having an outer diameter of about 10 to 500 nm are entangled around an aggregate grown with catalyst particles as nuclei. A plurality of the aggregates are gathered to form an aggregate containing carbon nanofibers of several centimeters to several tens of centimeters.

  The properties of these surface shapes vary depending on various manufacturing methods. In particular, defects are likely to occur when the annealing temperature of the surface of the carbon nanofiber is lowered. In the present embodiment, it is preferable to use non-graphitized carbon nanofibers in consideration of the desired physical properties and use of the polyamide resin composition containing carbon nanofibers. In general, the intermediate carbon nanofibers described above can be obtained by adjusting the annealing temperature of the non-graphitized carbon nanofibers. Specifically, the annealing temperature is preferably adjusted to about 900 to 1500 ° C.

Examples of an index for evaluating the degree of defects on the surface of the carbon nanofiber include a Raman scattering spectrum of the carbon nanofiber. Specifically, a spectrum having at least one peak top between 1565 and 1600 cm ⁻¹ (hereinafter referred to as “spectrum A”) is a spectrum that appears in common in a substance that is graphite, and is 1335 to 1365 cm ^−1. A spectrum having at least one peak top (hereinafter referred to as “spectrum B”) is a spectrum caused by a defect of carbon nanofibers. When there is a point defect in the carbon nanofiber or a defect at the end of the crystal, the intensity of the spectrum B becomes strong, so the relative intensity with the spectrum A is a measure of the degree of defect.

Therefore, the ratio (D / G) of the peak area (D) of the band between 1335 and 1365 cm ⁻¹ to the peak area (G) of the band between 1565 and 1600 cm ^{−1 in} the Raman scattering spectrum of the carbon nanofiber is large. In other words, it can be said that the degree of defects on the surface of the carbon nanofiber is large.

(B) The ratio (D / G) of the peak area (D) of the band between 1335 and 1365 cm ⁻¹ to the peak area (G) of the band between 1565 and 1600 cm ^{−1 in} the Raman scattering spectrum of the carbon nanofiber. Although not particularly limited, it is preferably 1.0 or more, more preferably 1.0 to 1.8, still more preferably 1.0 to 1.6, and still more preferably 1.0 to 1. .4. When the ratio (D / G) of the carbon nanofiber is within the above range, the dispersibility of the carbon nanofiber is improved. Ratio (D / G) here is a ratio of carbon nanofibers before kneading with (A) polyamide resin or (C) fibrous reinforcing material, and is contained in the polyamide resin composition (B) It is not the ratio of carbon nanofibers. This ratio (D / G) can be measured by the method described in Examples described later.

  The carbon nanofiber may be a carbon nanofiber branched to such an extent that a strong aggregate (aggregate in which the fibers are closely entangled) is not formed within the scope of the effect of the present embodiment. The degree of branching of the carbon nanofibers before the surface treatment is preferably smaller. Specifically, the number of fibers branched from one fiber is preferably 5 or less, more preferably 3 or less. .

  (B) The average fiber diameter of carbon nanofiber is 1 nm-500 nm normally, Preferably it is 5 nm-200 nm, More preferably, it is 8 nm-150 nm. By setting the lower limit of the average fiber diameter to the above value, the dispersibility of the carbon nanofibers can be further improved. By setting the upper limit of the average fiber diameter to the above value, the mechanical properties of the polyamide resin composition can be further improved. The average fiber diameter here is measured by a scanning electron microscope. The average fiber diameter here is the average fiber diameter of carbon nanofibers before kneading with (A) polyamide resin or (C) fibrous reinforcing material, and is included in the polyamide resin composition (B) carbon It is not the average fiber diameter of nanofibers.

  (B) The average fiber length of the carbon nanofiber is usually several tens nm to several thousand μm, preferably 0.8 μm to 500 μm, and more preferably 1 to 100 μm. By setting the lower limit of the average fiber length to the above value, the mechanical properties and conductivity of the polyamide resin composition can be further improved. By setting the upper limit of the average fiber length to the above value, the dispersibility of the carbon nanofibers in the polyamide resin composition can be further improved. The average fiber length here is the average fiber diameter of carbon nanofibers before kneading with (A) polyamide resin or (C) fibrous reinforcing material, and is included in the polyamide resin composition (B) carbon It is not the average fiber diameter of nanofibers.

  (B) As an additive that reacts with the carbon nanofibers, for example, an inorganic acid such as hydrogen peroxide or an organic acid such as maleic anhydride may be added. These may be treated in advance with (B) carbon nanofibers, or may be added during kneading of the extruder.

[(C) Fibrous reinforcement]
The (C) fibrous reinforcing material of the present embodiment is not particularly limited, and fibrous reinforcing materials having various materials, fiber diameters, and fiber lengths can be used. (C) Specific examples of the fibrous reinforcing material are not particularly limited, and examples thereof include glass fiber, metal fiber, carbon fiber, and other inorganic fibers. Among these, glass fiber is preferable.

  (C) When the fibrous reinforcing material is a glass fiber, the glass fiber length is preferably 1 to 10 mm and the average glass fiber diameter is 8 to 25 μm from the viewpoint of handling properties when kneading various components. . Moreover, (C) When a fibrous reinforcement is glass fiber, from a reinforcement effect and a dispersible viewpoint, the glass fiber length is 2-7 mm, and the average glass fiber diameter is 8-15 micrometers. Further, from the viewpoint of handling properties during kneading of various components, chopped short fibers are preferable as the glass fibers.

  The above-mentioned glass fiber length and average glass fiber diameter are values of (C) fibrous reinforcing material before kneading with (A) polyamide resin and (B) carbon nanofiber, and are included in the polyamide resin composition. It is not the value of (C) fibrous reinforcement.

  (C) The fibrous reinforcing material is surface-treated with a bundling agent for polyamide resin (this includes a bundling component for so-called sizing and a surface treatment component for adhesion between the polyamide resin). preferable. The sizing agent used here is, for example, at least one selected from the group consisting of a copolymer of maleic anhydride and an unsaturated monomer, a silane coupling agent, an acrylic acid copolymer, and a urethane polymer. And the like whose main constituent is one. Among these, a sizing agent containing a copolymer of maleic anhydride and an unsaturated monomer and an amino group-containing silane coupling agent is particularly preferable from the viewpoint of an effect of improving vibration fatigue characteristics.

  Specific examples of the copolymer of maleic anhydride and unsaturated monomer described above include styrene, α-methylstyrene, butadiene, isoprene, chloroprene, 2,3-dichlorobutadiene, 1,3-pentadiene, cyclohexane. And a copolymer of an unsaturated monomer such as octadiene and maleic anhydride. Among them, a copolymer of butadiene or styrene and maleic anhydride is particularly preferable.

  One type of unsaturated monomer may be used, or two or more types may be used in combination. Alternatively, two or more kinds of copolymers may be blended. For example, a maleic anhydride / butadiene copolymer and a maleic anhydride / styrene copolymer may be blended.

  The average molecular weight of the copolymer of maleic anhydride and unsaturated monomer described above is preferably 2,000 or more. The ratio of maleic anhydride and unsaturated monomer in the copolymer is not particularly limited. Furthermore, in addition to the maleic anhydride copolymer, an acrylic acid copolymer or a urethane polymer may be used in combination.

  As the silane coupling agent described above, any silane coupling agent usually used for surface treatment of glass fibers can be used. Specifically, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane Aminosilane coupling agents such as N-β (aminoethyl) γ-aminopropyltriethoxysilane; γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyl Epoxysilane coupling agents such as triethoxysilane; γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, etc. Metacloxisila System coupling agent; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris vinylsilane coupling agents such as (beta-methoxyethoxy) silane. Two or more of these coupling agents can be used in combination. Among these, aminosilane-based coupling agents are particularly preferable from the viewpoint of affinity with polyamide resin, and among them, γ-aminopropyltriethoxysilane and N-β (aminoethyl) γ-aminopropyltriethoxysilane are more preferable.

  Examples of the acrylic acid-based copolymer include acrylic acid homopolymers, acrylic acid-acrylic acid ester copolymers, acrylic acid-butyl copolymers, acrylic acid-maleic acid copolymers, and modified products thereof. Is mentioned.

  As the above-described urethane-based polymer, any urethane-based polymer that is usually used for surface treatment of glass fibers can be used.

  The content of the (A) polyamide resin in the polyamide resin composition is preferably 60 to 97% by mass, more preferably 65 to 96% by mass, and 70 to 95% from the viewpoint of tensile properties at high temperatures. More preferably, it is mass%.

  The content of (B) carbon nanofibers in the polyamide resin composition is preferably 0.1 to 15% by mass. When the content is 0.1% by mass or more, the fatigue characteristics at high temperatures of the polyamide resin composition are improved, and when the content is 15% by mass or less, stable extrudability can be secured. More preferably, it is 1-10 mass%, More preferably, it is 2-5 mass%.

  The content of the (C) fibrous reinforcing material in the polyamide resin composition is preferably 10 to 50% by mass. The tensile strength of a polyamide resin composition improves by setting it as 10 mass% or more, and the stable extrudability is securable by setting it as 50 mass% or less. More preferably, it is 10-35 mass%, More preferably, it is 10-25 mass%.

  The polyamide resin composition of the present embodiment may further contain an additive as necessary. The additive is not particularly limited, and various additives can be used as long as the object of the present embodiment is not impaired. Specific examples of the additive include a moldability improver, a colorant, a flame retardant, a plasticizer, a stabilizer, an antioxidant, and an ultraviolet absorber.

  The formability improver is not particularly limited, and examples thereof include higher fatty acids, higher fatty acid metal salts, higher fatty acid esters, and higher fatty acid amides.

  Specific examples of the higher fatty acid include stearic acid, palmitic acid, behenic acid, erucic acid, oleic acid, lauric acid, and montanic acid, which are saturated or unsaturated, linear or branched fatty acids having 8 to 40 carbon atoms. Group monocarboxylic acid and the like. Among these, stearic acid and montanic acid are preferable.

  A higher fatty acid metal salt is a metal salt of a higher fatty acid. As the metal element of the metal salt, elements of the first, second and third group of the periodic table, zinc and aluminum are preferable, and first and second group elements such as calcium, sodium, potassium and magnesium. And aluminum are more preferred. Specific examples of the higher fatty acid metal salt include calcium stearate, aluminum stearate, zinc stearate, magnesium stearate, calcium montanate, sodium montanate, calcium palmitate and the like. Among these, sodium montanate, calcium montanate, and calcium stearate are preferable.

  The higher fatty acid ester is an esterified product of a higher fatty acid and an alcohol. Among these, esters of an aliphatic carboxylic acid having 8 to 40 carbon atoms and an aliphatic alcohol having 8 to 40 carbon atoms are preferable. Here, as the higher fatty acid, those described above can be used. Examples of the aliphatic alcohol include stearyl alcohol, behenyl alcohol, and lauryl alcohol. Specific examples of higher fatty acid esters include stearyl stearate and behenyl behenate.

  A higher fatty acid amide is an amide compound of a higher fatty acid. Specific examples of higher fatty acid amides include stearic acid amide, oleic acid amide, erucic acid amide, ethylene bis stearyl amide, ethylene bis oleyl amide, N-stearyl stearyl amide, N-stearyl erucic amide and the like. Among these, stearic acid amide, erucic acid amide, ethylene bisstearyl amide, and N-stearyl erucic acid amide are preferable, and ethylene bisstearyl amide and N-stearyl erucic acid amide are more preferable.

  These higher fatty acids, higher fatty acid metal salts, higher fatty acid esters, and higher fatty acid amides may be used alone or in combination of two or more.

  Specific examples of colorants include dyes such as nigrosine; pigments such as titanium oxide and carbon black; metal particles such as aluminum, colored aluminum, nickel, tin, copper, gold, silver, platinum, iron oxide, stainless steel, and titanium. And mica pearl pigments, colored graphite, colored glass fibers, metallic pigments such as colored glass flakes, and the like.

  The flame retardant is preferably a non-halogen flame retardant or a bromine flame retardant.

  Specific examples of non-halogen flame retardants include phosphorus flame retardants such as red phosphorus, ammonium phosphate, ammonium polyphosphate, aluminum hydroxide, magnesium hydroxide, dolomite, hydrotalcite, calcium hydroxide, barium hydroxide, Metal hydroxides such as basic magnesium carbonate, zirconium hydroxide, tin oxide, zinc stannate, zinc hydroxystannate, or hydrates of inorganic metal compounds, boric acid such as zinc borate, zinc metaborate, barium metaborate Inorganic flame retardants such as compounds, melamine, melam, melem, melon (product of 3 molecules of ammonia released from 3 melem molecules at 300 ° C or higher), melamine cyanurate, melamine phosphate, melamine polyphosphate, Succinoguanamine, adipoguanamine, methylglutalogamine, melamine resin, etc. Triazine-based flame retardant, silicone resin, silicone oil, silicone flame retardants such as silica.

  Examples of the brominated flame retardant include brominated polystyrene, brominated polyphenylene ether, brominated bisphenol type epoxy polymer, brominated crosslinked aromatic polymer, and the like.

  Examples of the plasticizer include aliphatic alcohol, aliphatic amide, aliphatic bisamide, bisurea compound, polyethylene wax, octyl p-oxybenzoate, and N-butylbenzenesulfonamide.

  As the stabilizer, a deterioration inhibitor may be added for the purpose of thermal deterioration, prevention of discoloration during heating, heat aging resistance, and weather resistance. Degradation inhibitors include phenolic stabilizers such as copper compounds such as copper acetate and copper iodide and hindered phenol compounds, phosphite stabilizers, hindered amine stabilizers, triazine stabilizers, sulfur stabilizers, etc. It is done. Among these, an organic phosphorus compound and an inorganic phosphorus compound are preferable, and specifically, a metal salt of hypophosphorous acid is preferable.

  Examples of the antioxidant include alkylphenol, alkylene bisphenol, alkylphenol thioether and the like.

  Examples of the ultraviolet absorber include salicylic acid ester, benzotriazole, and hydroxybenzophenone.

  In addition to the above, a carbodiimide group-containing compound, an inorganic acid, an organic acid, a polymer copolymerized with an organic acid, or the like may be added as an additive that reacts with the polyamide resin or the surface-treated carbon nanofibers. These may be treated in advance with carbon nanofibers, or may be added during kneading of the extruder.

  The polyamide resin composition of the present embodiment may contain a resin other than the polyamide resin and a rubber component as necessary, as long as the object of the present embodiment is not impaired. Specifically, at least one selected from a thermoplastic resin, a thermosetting resin, and a rubber component can be used. Among these, a thermoplastic resin and a rubber component are preferable from the viewpoint that the effect of adding the surface-treated carbon nanofiber is excellent.

  The thermoplastic resin is not particularly limited as long as it can be used in the molding field. For example, polyethylene, polypropylene, polystyrene, ABS resin, polyacetal, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, modified polyphenylene ether, polyphenylene sulfide, Examples thereof include cycloolefin polymers, liquid crystal polymers, polyether imides, polysulfones, polyether sulfones, polyamide imides, thermoplastic polyimides, polyether ketones, polyether ether ketones, fluororesins, and polybenzimidazoles. These may be copolymers or modified products. Moreover, these 1 type may be used individually and may use 2 or more types together.

  The thermosetting resin is not particularly limited as long as it is a resin that can be used in the molding field. For example, epoxy resin, polyurethane, phenol resin, diallyl phthalate resin, unsaturated polyester resin, urea resin, melamine resin, silicone resin, Examples thereof include a polyimide resin and an allyl ester resin. These may be copolymers or modified products. Moreover, these 1 type may be used individually and may use 2 or more types together.

  The rubber component is not particularly limited. For example, natural rubber, polybutadiene, polyisoprene, polyisobutylene, neoprene, polysulfide rubber, thiocol rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber, styrene-butadiene block copolymer Copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene block Copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer ( EPS), styrene-butadiene random copolymer, hydrogenated styrene-butadiene random copolymer, styrene-ethylene-propylene random copolymer, styrene-ethylene-butylene random copolymer, ethylene-propylene copolymer (EPR) , Ethylene- (1-butene) copolymer, ethylene- (1-hexene) copolymer, ethylene- (1-octene) copolymer, ethylene-propylene-diene copolymer (EPDM), butadiene-acrylonitrile -Styrene-core shell rubber (ABS), methyl methacrylate-butadiene-styrene-core shell rubber (MBS), methyl methacrylate-butyl acrylate-styrene-core shell rubber (MAS), octyl acrylate-butadiene-styrene-core shell rubber (MA) S), core-shell type such as alkyl acrylate-butadiene-acrylonitrile-styrene core-shell rubber (ABS), butadiene-styrene-core shell rubber (SBR), siloxane-containing core-shell rubber including methyl methacrylate-butyl acrylate siloxane, silicone elastomer, Nitrile elastomers, butadiene elastomers, urethane elastomers, nylon elastomers, ester elastomers, fluorine elastomers, copolymers thereof, and modified products in which reactive sites (double bonds, anhydrous carboxyl groups, etc.) are introduced into the elastomers Etc. These rubber components may be used alone or in combination of two or more.

  The total amount of the resin and the rubber component other than the polyamide resin in the polyamide resin composition is not particularly limited, but is preferably 20% by mass or less, more preferably 15% by mass or less, and more preferably 10% by mass. More preferably, it is as follows. By making the total content of the resin other than the polyamide resin and the rubber component 20% by mass or less, the effect of adding the surface-treated carbon nanofibers can be further improved, and desired physical properties can be further improved.

Hereinafter, a suitable example of the method for producing the polyamide resin composition of the present embodiment will be described.
The manufacturing method of the polyamide resin composition of this embodiment includes (A) a polyamide resin; (D) (B) carbon nanofibers and (E) a modified rosin, a styrene resin, an olefin resin, and an acrylic acid resin. And a carbon nanofiber granule that contains at least one selected from the group consisting of the following formulas (1) and (2): and (C) a step of kneading the fibrous reinforcing material The method is preferred.

0.01 ≦ P1 ≦ 1 (1)
0 <P1 / P2 ≦ 3.3 (2)

P1: Maximum pore volume (cm ³ / g) at a pore diameter of 2,500 nm to 100,000 nm in pore distribution data measured with a mercury porosimeter
P2: Maximum pore volume (cm ³ / g) at a pore diameter of 6 nm or more and less than 2,500 nm in pore distribution data measured with a mercury porosimeter

  By adopting such a production method, it becomes easy to control the aspect ratio of the (B) carbon nanofiber in the polyamide resin composition. In addition, the dispersibility of (B) carbon nanofibers in the polyamide resin composition is improved.

[(D) Carbon nanofiber granule]
(D) The carbon nanofiber granule includes (B) carbon nanofiber and (E) at least one selected from the group consisting of a modified rosin, a styrene resin, an olefin resin, and an acrylic acid resin. And satisfying the relationship of the above-mentioned formulas (1) and (2). By using such (D) carbon nanofiber granules, the aspect ratio of (B) carbon nanofibers can be increased. In a preferred embodiment, the (D) carbon nanofiber granule using the component (E) preferably contains (B) carbon nanofibers in the form of granules.

  The maximum void volume P1 and the maximum void volume P2 can be measured by using a mercury porosimeter described later. The maximum void volume P1 and the maximum void volume P2 can be obtained by the method described in Examples described later.

  In order to improve the dispersibility of (B) carbon nanofibers in (A) polyamide resin, the present inventors have examined not only the macroscopic structure but also the microscopic structure of carbon nanofibers. We have obtained knowledge on controlling the void structure composed of pore size distribution obtained by porosimeter measurement. Further, (D) the carbon nanofiber granule controlled so as to have a void structure in which the above-described P1 and P2 satisfy the relations of the formulas (1) and (2), and (A) the molten polyamide resin By kneading, (B) the aspect ratio (L / D) of the carbon nanofibers can be increased, and (B) the carbon nanofibers can be well dispersed in the polyamide resin composition. I found it.

  Although it is not certain as these reasons, it is estimated as follows. When the above P1 and P2 have a void structure that satisfies the relationship of the formula (1) and the formula (2), (D) when the carbon nanofiber granule and (A) the polyamide resin are melt-kneaded. Each fiber can be dispersed in (A) the polyamide resin in a state where each fiber is unraveled. Furthermore, the dispersibility can be further improved by applying a shearing force generated during melt kneading. Still further, (D) the carbon nanofiber granule can be melt-kneaded to prevent (B) the carbon nanofiber from breaking and shortening the fiber length during kneading. (B) In order to make a composite material in which carbon nanofibers are highly filled with higher dispersibility, (D) carbon nanofiber granules may be added to (A) polyamide resin, or (D) carbon A master batch in which the nanofiber granulate is added to the (A) polyamide resin at a high concentration may be prepared, and the obtained master batch may be added. They can also be expected to improve various physical properties of the composite material depending on the application (however, the action of the present embodiment is not limited thereto).

  (D) The entangled structure of the carbon nanofiber (B) constituting the carbon nanofiber granulated body is not particularly limited, but preferably has a three-dimensionally assembled structure. The three-dimensionally assembled structure referred to here is a collective structure formed by a plurality of primary aggregates (an entangled structure of one carbon nanofiber) to be described later in contact or entangled. Secondary aggregate structures (secondary aggregate structures); and higher-order aggregate structures such as tertiary aggregate structures (tertiary aggregate structures) further assembled by a plurality of secondary aggregates are included. The dispersion state of the carbon nanofibers of this embodiment can also be observed by the measurement method described in the examples described later.

(D) It is preferable that the carbon nanofiber granule further satisfies the relationship of the following formula (3).

0.75 ≦ Q2 / (Q1 + Q2) <1 (3)

Q1: Integrated pore volume (cm ³ / g) at a pore diameter of 2,500 nm to 100,000 nm in pore distribution data measured with a mercury polysimeter
Q2: Accumulated void volume (cm ³ / g) at a pore diameter of 6 nm or more and less than 2,500 nm in pore distribution data measured with a mercury polysimeter

  The term “integrated void volume” as used herein refers to an integrated value of the volume in each pore diameter region of the pore distribution measured with a mercury porosimeter. The accumulated void volumes Q1 and Q2 can be obtained by the method described in Examples described later.

  Here, a preferred example in the case where the accumulated void volumes Q1 and Q2 satisfy the relationship of the above formula (3) will be described with reference to FIG. FIG. 1 is a conceptual diagram for explaining an example of (D) a carbon nanofiber granulated body. FIG. 1 is a diagram schematically illustrating an example of the structure of a preferred embodiment, and it goes without saying that the structure of (D) the carbon nanofiber granule is not limited to the illustrated contents. (D) In the carbon nanofiber granule, the cumulative void volume Q1 at a pore diameter of 2,500 to 100,000 nm corresponds to a large void formed between the tertiary aggregates shown in FIG. Conceivable. The cumulative void volume Q2 when the pore diameter is 6 nm or more and less than 2,500 nm is (i) voids inside the primary aggregate formed by intertwining one fiber and (ii) a plurality of primary aggregates. It is considered that it corresponds to the voids inside the secondary aggregates constituted by collecting, and (iii) the voids inside the tertiary aggregate constituted by collecting a plurality of secondary aggregates. By controlling the accumulated void volumes Q1 and Q2 so as to satisfy the relationship of the above formula (3), when (D) the carbon nanofiber granule and (A) the polyamide resin are melt-kneaded, (i) primary The melted resin can enter the fine voids such as the voids inside the aggregate and (ii) the voids inside the secondary aggregate, and the dispersibility can be further improved. Conventionally, microstructural control such as such integrated void volume has not been studied, and from this point of view, in this embodiment, various physical property improvements such as dispersibility have been improved to an unprecedented level. It is thought that it can be made excellent (however, the action of this embodiment is not limited to these).

  Further, when the accumulated void volumes Q1 and Q2 satisfy the relationship of the above formula (3), the conductivity of the (D) carbon nanofiber granule is further improved. From the viewpoint of making such a (D) carbon nanofiber granule, the average fiber diameter of the carbon nanofibers as a raw material is preferably 30 nm or less, and more preferably 25 nm or less.

  (D) The carbon nanofiber granule comprises (B) carbon nanofiber and (E) at least one selected from the group consisting of a modified rosin, a styrene resin, an olefin resin, and an acrylic acid resin. Is included. As a method for producing such a (D) carbon nanofiber granulated body, for example, a method in which powdered (B) carbon nanofiber and (E) component are wet mixed and then dried is preferable. According to this method, the void structure can be easily controlled with respect to the entanglement between the carbon nanofibers.

  In the manufacturing method of this embodiment, the aggregate structure and void structure of (B) carbon nanofibers in the polyamide resin composition can be efficiently controlled by using (D) carbon nanofiber granules. At that time, the above-described primary aggregate, secondary aggregate, and tertiary aggregate are controlled to have the configuration exemplified in FIG. 1, thereby exhibiting more excellent physical properties as a polyamide resin composition. However, from the viewpoint of forming and maintaining such a configuration, it is more preferable to take a configuration in which tertiary aggregates are firmly connected by the component (E). An example of such a preferable configuration will be described with reference to FIG.

  Drawing 2 is a key map for explaining the structure of another example of (D) carbon nanofiber granule. FIG. 2 is a diagram schematically illustrating an example of the structure of the preferred embodiment, and it goes without saying that the structure of the (D) carbon nanofiber granule is not limited to the illustrated contents. In FIG. 2, since the tertiary aggregates have a structure that is more strongly connected by the component (E), the specific aggregate structure as described in FIG. 1 and the like can be maintained more firmly. . Furthermore, since the component (E) is arranged only at the boundary of the tertiary aggregate and does not enter a finer void or the like, (i) the void inside the primary aggregate or (ii) the secondary aggregate. The molten resin can enter the fine voids such as the voids inside the aggregate at a higher filling rate. As a result, it is presumed that the dispersibility can be further improved (however, the operation of the present embodiment is not limited thereto).

  As described above, the organic substance such as the component (E) is presumed to play a role of bonding the carbon nanofibers together by chemical bonding or physical bonding. From this viewpoint, it is preferable not to use a component that forms a covalent bond with the component (B) at both ends of the molecular chain as the component (E). For example, the component (E) preferably has substantially no peroxide or azo compound at both ends of the molecular chain.

  The modified rosin is not particularly limited, and examples thereof include those obtained by reacting at least one rosin selected from the group consisting of tall rosin, gum rosin, and wood rosin with a modifying agent. Examples of the modifier include α, β-unsaturated carboxylic acids, polyhydric alcohols, phenols and the like. Among these, α, β-unsaturated carboxylic acids are preferable. These modifiers may be used alone or in combination of two or more. For example, when not only α, β-unsaturated carboxylic acids but also polyhydric alcohols and phenols are used in combination, these may be reacted simultaneously or sequentially.

  The α, β-unsaturated carboxylic acids are not particularly limited, and examples thereof include acrylic acid, methacrylic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, citraconic acid, and citraconic anhydride. It is done.

  Polyhydric alcohols are not particularly limited, and examples thereof include dihydric alcohols such as ethylene glycol, propylene glycol, neopentadiol, tetramethylene glycol, and 1,3-butanediol; trivalents such as glycerin and pentaerythritol. Alcohol; amino alcohols such as triethanolamine and tripropanolamine are listed.

  The styrene-based resin is not particularly limited. For example, polystyrene, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, styrene-maleimide copolymer, styrene-butadiene copolymer, styrene-butadiene- Examples thereof include acrylate copolymers, styrene-butadiene-methacrylate copolymers, and modified products thereof. In the case of a copolymer containing a monomer other than styrene, a copolymer having a styrene content of 50% by mass or more is preferable.

  The olefin resin is not particularly limited, and for example, polyethylene, ethylene-maleic acid copolymer, ethylene-maleic anhydride copolymer, ethylene-maleimide copolymer, ethylene-acrylate copolymer, ethylene-ethyl acrylate. Examples include copolymers, maleic acid-modified polyethylene, maleic anhydride-modified polyethylene, polypropylene, maleic acid-modified polypropylene, maleic anhydride-modified polypropylene, and the like. In addition, in the case of the copolymer containing other monomers other than an olefin, that whose content of olefin is 50 mass% or more in total is preferable.

  The acrylic resin is not particularly limited. For example, acrylic acid homopolymer, acrylic acid-acrylic acid ester copolymer, acrylic acid-butyl copolymer, acrylic acid-maleic acid copolymer, and those Examples include modified products. In addition, in the case of the copolymer containing other monomers other than acrylic acid, the total content of acrylic acid is preferably 50% by mass or more.

  From the viewpoint of (B) granulation of carbon nanofibers and (A) dispersibility of (B) carbon nanofibers with respect to polyamide resin, (B) the content of (E) modified rosin with respect to 100 parts by mass of carbon nanofibers. The total is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 40 parts by mass, and still more preferably 0.5 to 30 parts by mass.

  (E) The modified rosin is preferably emulsified. (E) Since the modified rosin is emulsified, it is presumed that the above-described primary to tertiary aggregates can be more firmly connected. The method of emulsifying the (E) modified rosin is not particularly limited, but a method of emulsifying the (E) modified rosin using a surfactant is preferred. From this point of view, when the modified rosin is used as the component (E), it is preferable to further include not only the (E) modified rosin but also a surfactant.

  The emulsification method is not particularly limited, and examples thereof include a solvent type emulsification method, a solventless type emulsification method, and a phase inversion emulsification method. (D) The carbon nanofiber granulated body is preferably produced, for example, by mixing (wet mixing or the like) (B) carbon nanofiber and (E) an emulsion of modified rosin. As the emulsion of (E) modified rosin, one obtained by emulsifying (E) modified rosin with a surfactant is more preferable.

  The surfactant is not particularly limited, and examples thereof include an anionic surfactant, a nonionic emulsifier, an amphoteric emulsifier, and a synthetic polymer emulsifier.

  The anionic surfactant is not particularly limited, and examples thereof include fatty acids such as sodium stearate, sodium oleate, and sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium dodecyldiphenyl ether disulfonate, and the like.

  The nonionic surfactant is not particularly limited, and examples thereof include polyoxyethylene alkyl (or alkenyl) ethers, polyethylene alkylphenyl ethers, sorbitan higher fatty acid esters, polyoxyethylene higher fatty acid esters, glycerin higher fatty acid esters. And polyoxyethylene-polyoxypropylene block polymers.

  The amphoteric surfactant is not particularly limited, and examples thereof include sulfation / sulfonation of a product condensate of aminocarboxylic acid, imidazoline bentine, carboxybentine, sulfobetaine, (ethylenoxide or polypyrenoxide) and (alkylamine or diamine). Examples include adducts.

  The synthetic polymer surfactant is not particularly limited, and examples thereof include polymerizable monomers (for example, styrene, acrylic acid, acrylate ester, α-methylstyrene, vinyltoluene, maleic acid, acrylamide, vinyl acetate, styrene). A polymer obtained by polymerizing two or more of sulfonic acid, isoprenesulfonic acid, vinylsulfonic acid, allylsulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, etc.) with an alkali (for example, hydroxylated) Examples thereof include water-dispersible polymers which are salt-formed with sodium, potassium hydroxide, ammonia, etc.) and dispersed or solubilized in water.

  (E) From the viewpoint of emulsifying the modified rosin, (D) the carbon nanofiber granule comprises (B) 100 parts by mass of carbon nanofibers, (E) 0.1 to 50 parts by mass of modified rosin, and surface activity. 0.01 to 30 parts by mass of an agent, (B) 100 parts by mass of carbon nanofibers, (E) 0.1 to 40 parts by mass of a modified rosin, and 0.01 to 20 parts by mass of a surfactant. And more preferably. By making the content of (B) carbon nanofiber, (E) modified rosin, and surfactant within the above ranges, (E) particles composed of modified rosin and surfactant are efficiently joined together, and (D) carbon Nanofiber granules can be obtained. Moreover, at the time of melt-kneading (A) polyamide resin and (D) carbon nanofiber granulated material, the molten polyamide resin can further penetrate into the voids of (D) carbon nanofiber granulated material. Furthermore, it is possible to disperse the carbon nanofibers in the polyamide resin in a state where each carbon nanofiber is unwound by applying a shearing force generated during melt-kneading. As a result, it is possible to prevent a decrease in the aspect ratio of the (B) carbon nanofiber during melt-kneading.

  (E) The average particle diameter of the modified rosin emulsion is preferably 0.05 to 5 μm, more preferably 0.1 to 1 μm. In order to obtain such an average particle size, conditions such as the type and amount of the surfactant used when preparing the emulsion and the stirring force of the solution may be appropriately adjusted. The average particle diameter here refers to the volume average particle diameter. The volume average particle diameter can be measured using a laser diffraction / scattering particle size distribution analyzer. (E) The modified rosin emulsion particles are preferably substantially spherical.

  In the present embodiment, for example, the value of P1 in the formula (1) can be further controlled by adjusting the average particle diameter of the emulsion. For example, the use of an emulsion having a small average particle size tends to increase the value of P1, and the use of an emulsion having a large average particle size tends to decrease the value of P1. When the average particle size of the emulsion of component (E) is 5 μm or less, the value of P1 tends to increase, and the particles of the emulsion of component (E) are only present in the voids between the tertiary aggregates of carbon nanofibers. Can be arranged. And the emulsion particle | grains of (E) component will enter into the space | gap formed by the secondary aggregates corresponding to the accumulation space | gap volume Q2, the space | gap formed by primary aggregates, and the space | gap of a primary aggregate. This can be suppressed. As a result, a more preferable spatial arrangement of carbon nanofibers can be realized. Thereby, when the (D) carbon nanofiber granule of this embodiment is melt kneaded with the (A) polyamide resin, the dispersibility of the (B) carbon nanofiber in the (A) polyamide resin is further improved. (However, the operation of the present embodiment is not limited to this).

  And the value of P1 / P2 in Formula (2) can be further controlled by adjusting the average particle diameter of emulsion, the average fiber diameter of (B) carbon nanofiber, and the compounding quantity of (E) component. . For example, the value of P1 / P2 tends to be increased by using an emulsion having a small average particle diameter, and the value of P1 / P2 can be decreased by using an emulsion having a large average particle diameter. There is a tendency. Further, by setting the content of the component (E) to 50 parts by mass or less with respect to 100 parts by mass of the (B) carbon nanofibers, voids formed by secondary aggregates corresponding to the accumulated void volume Q2, primary aggregation It can suppress that the emulsion particle | grains of (E) component enter the space | gap formed by aggregates, and the space | gap of a primary aggregate. As a result, a more preferable spatial arrangement of carbon nanofibers can be realized. Thereby, when (D) the carbon nanofiber granule is melt-kneaded with (A) the polyamide resin, the dispersibility of (B) the carbon nanofiber with respect to (A) the polyamide resin can be further improved (however, The operation of this embodiment is not limited to this.)

  Moreover, the value of Q2 / (Q1 + Q2) in Formula (3) can be further controlled by adjusting the average particle size of the emulsion and the blending amount of the component (E). For example, by using an emulsion having a small average particle size, the value of Q2 / (Q1 + Q2) tends to be increased. By using an emulsion having a large average particle size, the value of Q2 / (Q1 + Q2) is decreased. Tend to be able to. In addition, by setting the content of the component (E) to 50 parts by mass or less with respect to 100 parts by mass of the (B) carbon nanofibers, voids formed by secondary aggregates corresponding to the accumulated void volume Q2 are obtained. It can suppress that (E) component penetrates into the space | gap formed by aggregates, and the space | gap of a primary aggregate. Therefore, the value of Q1 becomes small, and the value of Q2 tends to be maintained at the value of Q2 of the raw carbon nanofibers. Further, when the average particle size of the emulsion is 0.05 μm or more, the value of Q1 tends to be small. Thereby, when (D) the carbon nanofiber granule is melt-kneaded with (A) the polyamide resin, the dispersibility of (B) the carbon nanofiber with respect to (A) the polyamide resin can be further improved (however, The operation of this embodiment is not limited to this.)

  (D) The carbon nanofiber granulated body is preferably produced, for example, by a wet mixing method of carbon nanofibers and an emulsion composed of a modified rosin and a surfactant. Examples of the method for producing a (D) carbon nanofiber granule containing carbon nanofibers, modified rosin and a surfactant include the following methods. High-speed stirrers such as carbon nanofibers, modified rosins and surfactants, Henschel mixers, super mixers, etc .; ball mills; paint shakers; roller kneaders, single screw extruders, multi-screw extruders such as twin screw extruders, etc. Blender; Mixer; Wet mix using media mill or the like. The obtained mixture is granulated and molded by an extrusion molding machine, a compression molding machine, a stirrer, a fluidized bed granulator, etc., and dried by a dryer or a heater (D) to produce a carbon nanofiber granulated body. . In particular, it is preferable to use a mixer capable of obtaining a high shear force, such as a high-speed stirrer such as a Henschel type mixer or a super mixer, and a multi-screw extruder such as a twin screw extruder.

  (D) The carbon nanofiber granulated material has a particle size that passes through a sieve having a nominal opening defined by JIS Z8801-1 in the total amount of more than 0.3 mm and not more than 4.75 mm. It is preferable that the content rate of a body is 90 mass% or more, and it is more preferable that it is 93 mass% or more. Specifically, (D) the carbon nanofiber granule is classified through the sieve described above, and the content of the carbon nanofiber granule having the above particle size is set in the above range, whereby in the polyamide resin composition Dispersibility of carbon nanofibers is further improved. From this point of view, in particular, (B) a carbon nanofiber and (E) a modified rosin component, and (D) a nominal opening defined in JIS Z8801-1 in the total amount of carbon nanofiber aggregates It is more preferable that the content of the carbon nanofiber granule having a particle size passing through a sieve that exceeds 0.3 mm and not more than 4.75 mm is 90% by mass or more.

  In order to obtain a larger aspect ratio (L / D), the manufacturing method of the polyamide resin composition of the present embodiment first includes a step of melt-kneading (D) the carbon nanofiber granule and (A) the polyamide resin. It is preferable to have. As a specific example, after mixing (D) the carbon nanofiber granule and (A) polyamide resin by hand mixing in a mixer or a bag, a kneader; a batch kneader such as a Banbury mixer; Examples thereof include a roll kneader; a single-screw extruder; and a method of heat-melt kneading in a multi-screw extruder such as a twin-screw extruder. In the conventional composite material of carbon nanofibers and polyamide resin, it is difficult to form a good dispersion state of carbon nanofibers in the polyamide resin. However, in this embodiment, surprisingly, (D) carbon By using the nanofiber granulated material, the above-described excellent dispersion state can be constituted only by kneading with a thermoplastic resin by a simple kneading method. As a manufacturing method of the polyamide resin composition of this embodiment, it is preferable to heat-melt-knead using batch type kneaders, such as a kneader, and multi-screw extruders, such as a twin-screw extruder.

  The polyamide resin composition supplies a predetermined amount of (A) polyamide resin from a feed hole (top feed) located on the most upstream side using, for example, a twin screw extruder. And when (A) polyamide resin reaches a molten state, (D) carbon nanofiber granulated material, (C) fibrous reinforcing material, and pellet-shaped new (A) polyamide resin are added by a predetermined amount. It is obtained by side-feeding, forming into a strand shape with a spinning hole attached to the downstream end of the extruder, and then cooling and cutting. By side-feeding the pellet-shaped (A) polyamide resin, the melt viscosity of the molten polyamide resin is increased and the shearing force is increased. This improves the dispersibility of the carbon nanofibers. Moreover, (D) By using the carbon nanofiber granule, the breakage of the carbon nanofiber itself due to melt-kneading is suppressed, and the aspect ratio (L / D) of the carbon nanofiber in the resin composition is maintained. Is possible. In addition, the position to side feed the (D) carbon nanofiber granule and the (C) fibrous reinforcing material is not particularly limited. For the purpose of suppressing fiber breakage of the (C) fibrous reinforcing material, (C) fiber It is preferable to side-feed the reinforcing material from the most downstream side.

  The temperature (melt kneading temperature) for melting and kneading (A) polyamide resin, (B) carbon nanofiber (or (D) carbon nanofiber aggregate), (C) fibrous reinforcing material and other components is not particularly limited. When a polyamide resin having a melting point is used, the melt kneading temperature is preferably equal to or higher than the melting point of the polyamide resin, and more preferably (melting point of polyamide resin + 50) ° C. or lower. When a polyamide resin having no melting point is used, the melt kneading temperature is preferably (polyamide resin glass transition temperature + 50) ° C. or higher, and preferably (polyamide resin glass transition temperature + 150) ° C. or lower. The melting point and glass transition temperature of polyamide can be measured by using a differential scanning calorimetry (DSC) apparatus.

The shear rate of the extruder used when melt-kneading carbon nanofibers, polyamide resin, and other components is usually about 10 to 10000 sec ⁻¹ . The shear history time is usually about 10 to 1200 seconds.

  The polyamide resin composition of the present embodiment can be molded and used as various members. Examples of a method for molding a polyamide resin composition and obtaining a molded body include, for example, extrusion molding, injection molding, vacuum molding, blow molding, injection compression molding, decorative molding, molding of other materials, gas assist injection molding, and firing injection molding. Known molding methods such as low-pressure molding, ultra-thin wall injection molding (ultra-high-speed injection molding), and in-mold composite molding (insert molding, outsert molding) can be used.

  The molded body of the polyamide resin composition can be molded into various shapes depending on the application. For example, it can be formed into various shapes such as pellets, fibers, threads, sheets, films, plates, rods, fibers and the like.

  The molded body of polyamide resin composition is excellent in tensile strength and conductivity, so it can be used in a wide range of applications such as automobile parts, electrical parts, electronic parts, portable electronic equipment parts, mechanical / industrial parts, office equipment parts, aerospace parts, etc. Can be used. Moreover, since it is excellent in fatigue characteristics (tensile creep) at high temperatures, it can be suitably used for applications requiring a long life of parts (for example, automobile parts, aerospace parts, etc.).

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited at all by these Examples. In addition, content is based on a mass reference | standard unless there is particular notice. In this example, the following raw materials were used.

[(A) Polyamide resin]
(A-1) Polyamide 66 (trade name “Leona 1300S” manufactured by Asahi Kasei Chemicals Corporation)

[(B) Carbon nanofiber]
(B-1) Carbon nanofiber (a): average fiber diameter 15 nm, catalytic chemical vapor deposition method, to the peak area of the spectrum (G) having a peak top during 1565～1600Cm ^-1 of 1335～1365Cm ^-1 Ratio of peak area (D) of spectrum having peak top in between (D / G) = 1.2 (made by Showa Denko KK, trade name “VGCF-X”)
(B-2) Carbon nanofiber (b): manufactured by Hyperion Catalysis Co., Ltd., polyamide 66 masterbatch containing 20% by mass of carbon nanofiber (trade name “MB4620-00”) (of which 80% by mass is (A) It is polyamide 66 as a component)
(B-3) Carbon nanofiber (c): an average fiber diameter of 15 nm, catalytic chemical vapor deposition method, to the peak area of the spectrum (G) having a peak top during 1565～1600Cm ^-1 of 1335～1365Cm ^-1 Ratio of peak area (D) of spectrum having peak top in between (D / G) = 0.2 (made by Showa Denko KK, trade name “VGCF-X” graphitized at 2500 ° C. or higher)

[(C) Fibrous reinforcement]
(C-1) Glass fiber: Glass fiber average diameter 10 μm, glass fiber average length 3 mm (manufactured by CPIC, trade name “301HP”)

[(D) Carbon nanofiber granule]
(D-1) Carbon nanofiber granule produced using (B-1) (carbon nanofiber 95% by mass, modified rosin 5% by mass)
(D-3) Carbon nanofiber granule produced using (B-3) (carbon nanofiber 95% by mass, modified rosin 5% by mass)

(Evaluation method)
[(B) Raman scattering spectrum (D / G) of carbon nanofiber before kneading]
A microscopic laser Raman analyzer (manufactured by Thermo Fisher Scientific, “Almega XR”) was used. First, (B) carbon nanofibers before being used for preparation of the polyamide resin composition (before kneading) were dried in a vacuum drying oven at 80 ° C. for 12 hours to obtain a measurement sample. Then, the peak area (D) of the spectrum having a peak top between 1335 and 1365 cm ⁻¹ with respect to the peak area (G) of the spectrum having a peak top between 1565 and 1600 cm ^{−1 in} the measurement sample by Raman scattering spectroscopy. The ratio (D / G) was measured. The peak area was calculated by performing curve fitting of the peak intensity. The measurement was performed 3 times in total, and the arithmetic average value of 3 times was taken as the measured value.

[Aspect ratio (L / D) of (B) carbon nanofibers in polyamide resin composition]
The aspect ratio (L / D) of the carbon nanofibers contained in the polyamide resin composition was measured by the following method. First, 0.1 g of the polyamide resin composition was put into 50 mL of hexafluoroisopropanol (HFIP) and allowed to stand to dissolve the polyamide resin component to obtain a solution.
The resulting solution was stirred with an ultrasonic bath for 20 minutes and then dropped on a 0.025 μm cellulose filter to obtain a residue. The filtrate was naturally dried to obtain a measurement sample. The obtained measurement sample was observed appropriately using a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, “S-4700”) or a transmission electron microscope (manufactured by Hitachi High-Technologies Corporation, “H-600”). The captured image was statistically analyzed using “Image-pro plus” (measurement number 200). And the ratio of the weight average length (L) with respect to the diameter (D) of a carbon nanofiber was calculated | required as an aspect ratio (L / D), the arithmetic average about the measurement number 200 was calculated | required, and it was set as the measured value.

[(B) Dispersibility of carbon nanofibers]
Evaluation was performed using 10 pellets prepared in each Example and each Comparative Example. Ten pellets were cut out one by one with a thickness of 2 μm using a microtome to obtain 10 measurement samples. The measurement sample was observed with an optical microscope (200 μm × 200 μm; magnification 400 times), and the dispersibility was evaluated based on the following criteria.

A: In the observation region of the optical microscope, only carbon nanofiber aggregates having a major axis length of less than 10 μm were observed. (The long axes of the carbon nanofiber aggregates observed in the observation region of the optical microscope were all less than 10 μm.)
B: In the observation region of the optical microscope, the number of carbon nanofiber aggregates having a major axis length of 10 μm or more and less than 30 μm was 10 or less.
C: In the observation region of the optical microscope, the number of carbon nanofiber aggregates having a major axis length of 30 μm or more and less than 50 μm was 5 or less.
D: One or more carbon nanofiber aggregates having a major axis length of 50 μm or more were confirmed in the observation region of the optical microscope.

[Preparation of molded article for physical property evaluation]
A Type 3 dumbbell molded product conforming to ISO 37 was produced and used as a molded product for evaluating physical properties. Specifically, a dumbbell molded body was produced according to the following method.
First, a small injection molding machine jacket (manufactured by DSM, “Xplore”) was connected to the strand outlet of the small laboratory kneader. And the polyamide resin composition melt | dissolved for 2 minutes was inject | poured in the small injection molding machine jacket. When the polyamide resin composition was injected into a small injection molding machine jacket, the jacket temperature was set to 300 ° C.
Next, the small injection molding machine jacket was removed from the small laboratory kneader, and this small injection molding machine jacket was set in a mold of a Type 3 dumbbell conforming to ISO 37. And the resin composition in the inside of a small injection molding machine jacket was extruded in the metal mold | die using the pressure cylinder connected to the small injection molding machine jacket rear part. The injection conditions were as follows. The dumbbell molded body thus obtained was used as a molded body for evaluating physical properties.
-Injection pressure 11 bar, injection time 30 seconds-Mold temperature of polyamide resin composition: 80 ° C

[120 ° C tensile strength at break]
First, a dumbbell test piece of ISO 37 Type 3 (length 16 mm × width 4 mm × thickness 2 mm of a parallel portion at a central portion between dumbbell chucks) was prepared. Using a tensile tester (manufactured by Shimadzu Corporation, “Autograph AG-5000D”), the temperature was raised to 120 ° C., and then a dumbbell was placed therein and left to stand for 30 minutes. The tensile strength and tensile elongation of the dumbbell were measured at a distance between chucks of 25 mm and a tensile speed of 50 mm / min. Further, the tensile elongation was calculated by the ratio of the elongation (displacement) at break to the distance between chucks.

[Fatigue properties (120 ° C tensile creep)]
The temperature was raised to 120 ° C. using a creep tester (manufactured by A & D Co., “CP6-L-250”), and then a dumbbell was placed therein and left to stand for 2 hours. The time (seconds) required until the dumbbell was deformed by 20% under a stress of 25 mm between chucks and 48 MPa was measured.

[Conductivity]
The dumbbell molded body obtained above was frozen and cut, and the cut surface was pasted with a silver paste agent (“Silbest P-255” manufactured by Nissin EM). The volume resistance value of the test piece vacuum-dried at 80 ° C. for 20 minutes was measured to evaluate the conductivity. It arrange | positioned on a shield board, the measurement probe was connected to the resistance measuring device (the product made by Advantest, "R8340A type"), and the volume resistance value was measured by the DC two-terminal method. The measured values were measured at 6 points for each test piece, and the average value was calculated.

[Measurement of void volume (P1, P2, Q1, Q2)]
The void volume (P1, P2, Q1, Q2) of the measurement sample was measured using a mercury porosimeter (manufactured by Quantachrom, PoleMaster PM-33GT). A measurement sample was filled in a cell with a volume of 3 mL, and after deaeration as a pretreatment, measurement was performed.
The number of measurement data was measured at 70 to 75 points in the pore diameter range of 3 to 100,000 nm. The obtained data was analyzed by “Quantachrome Foremaster for Windows (registered trademark) version 3.0” manufactured by Quantachrome.
P1 is the maximum peak value in a region having a pore diameter of 2,500 nm to 100,000 nm. P2 is the maximum peak value in a region having a pore diameter of 6 nm or more and less than 2,500 nm. Q1 is an integrated pore volume in a pore diameter range of 2500 nm to 100,000 nm, and indicates a void volume in this range. Q2 is the cumulative pore volume in the range of the pore diameter of 6 nm or more and less than 2,500 nm, and indicates the void volume in this range.

[Production Example 1] Carbon nanofiber granule (D-1)
100 g of modified rosin (trade name “135GN” manufactured by Harima Chemicals Co., Ltd.) was dissolved in 300 g of toluene to prepare a toluene solution of modified rosin. In addition, 900 mL of an aqueous solution having an active ingredient concentration of 10% by mass in a surfactant (trade name “New Coal 2320-SN” manufactured by Nippon Emulsifier Industry Co., Ltd.) was separately prepared. Then, these were added to a toluene solution, mixed with stirring and emulsified. Furthermore, this was made into the fine emulsion using the high-pressure emulsifier (made by Manton Gaurin). Toluene was removed by heating and vacuum distillation of the obtained fine emulsion under conditions of 100 mmHg to obtain an organic emulsion having a volume average particle size of 0.3 μm. The volume average particle diameter was measured according to the laser diffraction scattering method. Specifically, it was obtained as D50 of the particle size distribution using “SALD-300V” manufactured by Shimadzu Corporation.
Next, 100 g of carbon nanofibers (B-1) and water were added to a 20 L capacity Henschel mixer to make the volume about half that of the Henschel mixer.
To the organic emulsion prepared above, (B-1) the organic emulsion was added at a ratio of 10 parts by mass of the solid content in the organic emulsion with respect to 100 parts by mass of the carbon nanofibers, and 2000 rpm for 2 minutes. Stir and mix at high speed.
The obtained mixture was in the form of a slurry, and this was put into a wet extrusion granulator manufactured by Dalton Co. to obtain a columnar granulated product. The obtained granulated product was dried at 90 ° C. for 2 hours with an air dryer manufactured by Yamato Scientific Co., Ltd. to obtain a carbon nanofiber granulated product. The obtained carbon nanofiber granulated material was classified using a sieve having a nominal aperture of 2.36 mm as defined in JIS Z8801-1. The carbon nanofiber granules passed through the sieve were further classified using a sieve having a nominal opening of 1.18 mm. And the carbon nanofiber granule which remained on this sieve was vacuum-dried at 80 degreeC, and the target (D-1) carbon nanofiber granule was obtained.
When the void volume of the obtained (D-1) carbon nanofiber granule was measured with a mercury porosimeter, P1 was 0.25, P1 / P2 was 2.0, and Q2 / (Q1 + Q2) Was 0.80.

[Production Example 2] Carbon nanofiber granule (D-3)
(D-3) Carbon nanofiber granules were obtained in the same manner as in Production Example 1, except that the carbon nanofiber (B-1) was replaced with the carbon nanofiber (B-3).
When the void volume of the obtained (D-3) carbon nanofiber granule was measured with a mercury porosimeter, P1 was 0.27, P1 / P2 was 2.1, and Q2 / (Q1 + Q2) Was 0.85.

[Example 1]
A polyamide resin composition containing 88% by mass of component (A-1) shown in Table 1, 1.95% by mass of component (B-1), and 10% by mass of component (C-1) was prepared. By using “KZW15” (screw diameter: 15 mm, L / D ratio: 45) manufactured by Technobel, supplied from the feed hole (top feed) located on the upstream side at a ratio of 50% by mass of component (A-1), When the component (A-1) reaches a molten state, (D-1) component 2% by mass obtained above, (C-1) component 10% by mass, and (A-1) component 38% by mass. % Was supplied from the side feed, kneaded at a temperature of 300 ° C. and a rotation speed of 200 rpm to obtain strands, which were cooled with water and cut to obtain polyamide resin composition pellets.
About this pellet, the aspect-ratio (L / D) and dispersibility of (B-1) carbon nanofiber in a resin composition were evaluated. Furthermore, about this pellet, the 120 degreeC tensile test, the 120 degreeC tensile creep test, and the measurement of electroconductivity were implemented. These results are shown in Table 1.

[Example 2]
A pellet of the polyamide resin composition was obtained in the same manner as in Example 1 except that the components (A-1), (D-1), and (C-1) were all supplied from the top feed.
The component composition and physical property evaluation of this pellet are shown in Table 1.

[Comparative Example 1]
(A-1) component 80 mass% of Table 1, (B-2) component 10 mass% (8 mass% (content in resin composition) of this corresponds to (A) component), (C -1) A polyamide resin composition containing 10% by mass of a component was prepared. By using “KZW15” (screw diameter: 15 mm, L / D ratio: 45) manufactured by Technobel, supplied from the feed hole (top feed) located on the upstream side at a ratio of 50% by mass of component (A-1), When the component (A-1) reaches a molten state, the component (B-2) obtained is 10% by mass, the component (C-1) is 10% by mass, and the component (A-1) is 30% by mass. % Was supplied from the side feed and kneaded at a temperature of 300 ° C. and a rotation speed of 200 rpm to obtain a strand, which was cooled with water and cut to obtain a pellet of a polyamide resin composition.
The component composition and physical property evaluation of this pellet are shown in Table 1.

[Example 3]
A polyamide resin composition containing 73% by mass of component (A-1) shown in Table 1, 1.95% by mass of component (B-1), and 25% by mass of component (C-1) was prepared. By using “KZW15” (screw diameter: 15 mm, L / D ratio: 45) manufactured by Technobel, supplied from the feed hole (top feed) located on the upstream side at a ratio of 50% by mass of component (A-1), When the component (A-1) reaches a molten state, the component (D-1) 2% by mass obtained above, the component (C-1) 25% by mass, and the component (A-1) 23% by mass are obtained. % From a side feed, kneaded at a temperature of 300 ° C. and a rotational speed of 200 rpm, a strand is obtained, and this is cooled with water and cut, whereby pellets of the polyamide resin composition having the component composition shown in Table 1 are obtained. Obtained.
The component composition and physical property evaluation of this pellet are shown in Table 1.

[Comparative Example 2]
(A-1) component 73 mass% of Table 1, (B-2) component 10 mass% (Of this, 8 mass% (resin composition content) corresponds to (A) component), (C-1 ) A polyamide resin composition containing 25% by mass of component was prepared. By using “KZW15” (screw diameter: 15 mm, L / D ratio: 45) manufactured by Technobel, supplied from the feed hole (top feed) located on the upstream side at a ratio of 50% by mass of component (A-1), When the component (A-1) reaches a molten state, the component (B-2) obtained above is 10% by mass, the component (C-1) is 25% by mass, and the component (A-1) is 23% by mass. % From a side feed, kneaded at a temperature of 300 ° C. and a rotational speed of 200 rpm, a strand is obtained, and this is cooled with water and cut, whereby pellets of the polyamide resin composition having the component composition shown in Table 1 are obtained. Obtained.
The component composition and physical property evaluation of this pellet are shown in Table 1.

[Example 4]
A polyamide resin composition containing 93% by mass of component (A-1) shown in Table 1, 1.95% by mass of component (B-1), and 5% by mass of component (C-1) was prepared. By using “KZW15” (screw diameter: 15 mm, L / D ratio: 45) manufactured by Technobel, supplied from the feed hole (top feed) located on the upstream side at a ratio of 50% by mass of component (A-1), When the (A-1) component reaches a molten state, (D-1) component 2% by mass, (C-1) component 5% by mass, and (A-1) component 43% by mass obtained above. % From a side feed, kneaded at a temperature of 300 ° C. and a rotational speed of 200 rpm, a strand is obtained, and this is cooled with water and cut, whereby pellets of the polyamide resin composition having the component composition shown in Table 1 are obtained. Obtained.
The component composition and physical property evaluation of this pellet are shown in Table 1.

[Comparative Example 3]
(A-1) component 85 mass% of Table 2, (B-2) component 10 mass% (8 mass% of this (content in a resin composition) corresponds to (A) component), (C -1) A polyamide resin composition containing 5% by mass of the component was prepared. By using “KZW15” (screw diameter: 15 mm, L / D ratio: 45) manufactured by Technobel, supplied from the feed hole (top feed) located on the upstream side at a ratio of (A-1) 50% by mass, When the component (A-1) reaches the molten state, the component (B-2) obtained above is 10% by mass, the component (C-1) is 5% by mass, and the component (A-1) is 35% by mass. Is fed from the side feed at a rate of 300 ° C. and kneaded at a rotational speed of 200 rpm to obtain a strand, which is cooled with water and cut to obtain polyamide resin composition pellets having the composition shown in Table 2. It was.
The component composition and physical property evaluation of this pellet are shown in Table 2.

[Example 5]
A polyamide resin composition containing 72% by mass of component (A-1), 2.85% by mass of component (B-1) and 25% by mass of component (C-1) described in Table 2 was prepared. By using “KZW15” (screw diameter: 15 mm, L / D ratio: 45) manufactured by Technobel, supplied from the feed hole (top feed) located on the upstream side at a ratio of 50% by mass of component (A-1), When the component (A-1) reaches a molten state, (D-1) component 3% by mass, (C-1) component 25% by mass, and (A-1) component 22% by mass obtained above. % From a side feed, kneaded at a temperature of 300 ° C. and a rotation speed of 200 rpm to obtain a strand, which is cooled with water and cut, whereby pellets of the polyamide resin composition having the component composition shown in Table 2 are obtained. Obtained.
The component composition and physical property evaluation of this pellet are shown in Table 2.

[Comparative Example 4]
60% by mass of component (A-1) and 15% by mass of component (B-2) shown in Table 2 (of which 12% by mass (content in the resin composition) corresponds to component (A)), (C -1) A polyamide resin composition containing 25% by mass of component was prepared. By using “KZW15” (screw diameter: 15 mm, L / D ratio: 45) manufactured by Technobel, supplied from the feed hole (top feed) located on the upstream side at a ratio of 50% by mass of component (A-1), When the component (A-1) reaches a molten state, the component (B-2) obtained is 15% by mass, the component (C-1) is 25% by mass, and the component (A-1) is 10% by mass. % From a side feed, kneaded at a temperature of 300 ° C. and a rotation speed of 200 rpm to obtain a strand, which is cooled with water and cut, whereby pellets of the polyamide resin composition having the component composition shown in Table 2 are obtained. Obtained.
The component composition and physical property evaluation of this pellet are shown in Table 2.

[Comparative Example 5]
70% by mass of component (A-1) and 10% by mass of component (B-2) listed in Table 2 (of which 8% by mass (content in the resin composition) corresponds to component (A)), (C -1) A polyamide resin composition containing 20% by mass of a component was prepared. By using “KZW15” (screw diameter: 15 mm, L / D ratio: 45) manufactured by Technobel, supplied from the feed hole (top feed) located on the upstream side at a ratio of 50% by mass of component (A-1), When the component (A-1) reaches a molten state, the component (B-2) obtained is 10% by mass, the component (C-1) is 20% by mass, and the component (A-1) is 20% by mass. % From a side feed, kneaded at a temperature of 300 ° C. and a rotation speed of 200 rpm to obtain a strand, which is cooled with water and cut, whereby pellets of the polyamide resin composition having the component composition shown in Table 2 are obtained. Obtained.
The component composition and physical property evaluation of this pellet are shown in Table 2.

[Example 6]
A polyamide resin composition containing 87% by mass of (A-1) component, 2.85% by mass of (B-1) component, and 10% by mass of (C-1) component described in Table 2 was prepared. By using “KZW15” (screw diameter: 15 mm, L / D ratio: 45) manufactured by Technobel, supplied from the feed hole (top feed) located on the upstream side at a ratio of 50% by mass of component (A-1), When the component (A-1) reaches a molten state, the component (D-1) 3% by mass obtained above, the component (C-1) 10% by mass, and the component (A-1) 37% by mass. % From a side feed, kneaded at a temperature of 300 ° C. and a rotation speed of 200 rpm to obtain a strand, which is cooled with water and cut, whereby pellets of the polyamide resin composition having the component composition shown in Table 2 are obtained. Obtained.
The component composition and physical property evaluation of this pellet are shown in Table 2.

.
[Example 7]
A polyamide resin composition containing 88% by mass of component (A-1) described in Table 2, 1.95% by mass of component (B-1), and 10% by mass of component (C-1) was prepared. By using “KZW15” (screw diameter: 15 mm, L / D ratio: 45) manufactured by Technobel, supplied from the feed hole (top feed) located on the upstream side at a ratio of 50% by mass of component (A-1), When the component (A-1) reaches a molten state, (D-1) component 2% by mass obtained above, (C-1) component 10% by mass, and (A-1) component 38% by mass. % From a side feed, kneaded at a temperature of 300 ° C. and a rotation speed of 200 rpm to obtain a strand, which is cooled with water and cut, whereby pellets of the polyamide resin composition having the component composition shown in Table 2 are obtained. Obtained.
The component composition and physical property evaluation of this pellet are shown in Table 2.

  The polyamide resin composition according to the present invention can be widely used including automobile parts and the like.

Claims (11)

A polyamide resin composition comprising (A) a polyamide resin, (B) carbon nanofibers, and (C) a fibrous reinforcing material,
The polyamide resin composition whose (B) carbon nanofiber aspect ratio (L / D) in the said polyamide resin composition is 40 or more.   When the polyamide resin composition is molded into pellets, the pellets are cut into a thickness of 2 μm using a microtome, and observed with an optical microscope (400 ×) at a viewing angle of 200 μm × 200 μm. The polyamide resin composition according to claim 1, wherein aggregates of fibers are observed, and the major axis of each aggregate is less than 10 μm. The ratio of the peak area (D) of the band between 1335 and 1365 cm ⁻¹ to the peak area (G) of the band between 1565 and 1600 cm ⁻¹ of the Raman scattering spectrum of the (B) carbon nanofiber (D / G ) Is 1.0 or more, the polyamide resin composition according to claim 1 or 2.   The polyamide resin composition according to any one of claims 1 to 3, wherein a content of the (B) carbon nanofiber in the polyamide resin composition is 0.1 to 15% by mass.   The polyamide resin composition according to any one of claims 1 to 4, wherein a content of the (C) fibrous reinforcing material in the polyamide resin composition is 10 to 50% by mass.   The polyamide resin composition according to any one of claims 1 to 5, wherein the (A) polyamide resin is polyamide 66. (A) the polyamide resin; (D) the (B) carbon nanofibers and (E) at least one selected from the group consisting of a modified rosin, a styrene resin, an olefin resin, and an acrylic resin. Any one of Claims 1-6 obtained by knead | mixing the carbon nanofiber granule which satisfy | fills the relationship of following formula (1) and Formula (2), and said (C) fibrous reinforcement. The polyamide resin composition according to item.

0.01 ≦ P1 ≦ 1 (1)
0 <P1 / P2 ≦ 3.3 (2)

P1: Maximum pore volume (cm ³ / g) at a pore diameter of 2,500 nm to 100,000 nm in pore distribution data measured with a mercury porosimeter
P2: Maximum pore volume (cm ³ / g) at a pore diameter of 6 nm or more and less than 2,500 nm in pore distribution data measured with a mercury porosimeter (A) the polyamide resin;
(D) including (B) the carbon nanofiber and (E) at least one selected from the group consisting of a modified rosin, a styrene resin, an olefin resin, and an acrylic acid resin, and the following formula (1) and A carbon nanofiber granule satisfying the relationship of formula (2);
(C) fibrous reinforcing material;
The manufacturing method of the polyamide resin composition of any one of Claims 1-6 including the process of knead | mixing.

0.01 ≦ P1 ≦ 1 (1)
0 <P1 / P2 ≦ 3.3 (2)

P1: Maximum pore volume (cm ³ / g) at a pore diameter of 2,500 nm to 100,000 nm in pore distribution data measured with a mercury porosimeter
P2: Maximum pore volume (cm ³ / g) at a pore diameter of 6 nm or more and less than 2,500 nm in pore distribution data measured with a mercury porosimeter The manufacturing method of the polyamide resin composition of Claim 8 with which the said (D) carbon nanofiber granule further satisfy | fills the relationship of following formula (3).

0.75 ≦ Q2 / (Q1 + Q2) <1 (3)

Q1: Integrated pore volume (cm ³ / g) at a pore diameter of 2,500 nm to 100,000 nm in pore distribution data measured with a mercury polysimeter
Q2: Accumulated void volume (cm ³ / g) at a pore diameter of 6 nm or more and less than 2,500 nm in pore distribution data measured with a mercury polysimeter   (D) The carbon nanofiber granule having a particle size that passes through a sieve having a nominal opening defined by JIS Z8801-1 in excess of 0.3 mm and not more than 4.75 mm in the total amount of the carbon nanofiber granule. The manufacturing method of the polyamide resin composition of Claim 8 or 9 whose content rate is 90 mass% or more.   The molded object containing the polyamide resin composition of any one of Claims 1-7.