Fiber-reinforced resin composition and molded article

Abstract

To provide a fiber-reinforced resin composition capable of producing a molded article with high impact resistance.SOLUTION: A fiber-reinforced resin composition comprises a first thermoplastic resin (A) forming a matrix, a second thermoplastic resin (B) different from the first thermoplastic resin (A), and carbon fibers (C). In the fiber-reinforced resin composition, the average thickness of an interfacial resin layer that is present at an interface between the carbon fibers (C) and the matrix and formed by the second thermoplastic resin (B) is from 10.00 nm to 80.00 nm inclusive.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a fiber-reinforced resin composition and a molded article. [Background technology]

[0002] BACKGROUND ART Fiber-reinforced resin compositions, which are resin compositions containing reinforcing fibers, are used in a variety of applications because they can be used to mold lightweight, high-strength molded articles.

[0003] As such a fiber-reinforced resin composition, Patent Document 1 describes a polyamide resin composition in which carbon fibers aligned in the length direction and bundled are impregnated with a polyamide resin that satisfies specific conditions and cut into lengths of 5 to 25 mm. Patent Document 1 also describes that by using a polyamide resin having an amino group concentration of 40 mmol / kg or more and setting the proportion of the polyamide resin to 60 to 95 mass% and the proportion of the carbon fiber to 5 to 40 mass% of the total amount of the polyamide resin and the carbon fiber, the impact resistance of a molded article obtained from the polyamide resin composition can be improved. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-155158 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 describes that a molded article (fiber-reinforced resin) with high impact resistance can be produced from a carbon fiber-reinforced polyamide resin composition having a specific composition. However, while fiber-reinforced resins are often used as various reinforcing materials, molded articles produced from the composition described in Patent Document 1 sometimes have insufficient impact resistance.

[0006] In view of the above problems, an object of the present invention is to provide a fiber-reinforced resin composition that can give a molded article having high impact resistance, and a molded article obtained by molding the fiber-reinforced resin composition. [Means for solving the problem]

[0007] One aspect of the present invention for solving the above problems relates to the following fiber-reinforced resin compositions [1] to

[12] . [1] A first thermoplastic resin (A) constituting a matrix; a second thermoplastic resin (B) which is an acid-modified resin different from the first thermoplastic resin (A); Carbon fiber (C), the average thickness of an interfacial resin layer formed by the second thermoplastic resin (B) and present at the interface between the carbon fiber (C) and the matrix is ​​10.00 nm or more and 80.00 nm or less; Fiber-reinforced resin composition. [2] The carbon fiber (C) has a ratio [O / C] of the number of oxygen (O) atoms to the total number of oxygen atoms (O) and carbon atoms (C) on the surface of the fiber (C) of 15.00 or more and 60.00 or less. [1] The fiber-reinforced resin composition according to the present invention. [3] The carbon fiber (C) has a surface ratio of hydroxyl groups to the total amount of carbon atoms (C), hydroxyl groups (OH), and carboxyl groups (COOH) [OH / (C+OH+COOH)] of 30.00% or more and 80.00% or less. The fiber-reinforced resin composition according to [1] or [2]. [4] The second thermoplastic resin (B) is an acid-modified polyolefin. The fiber-reinforced resin composition according to any one of [1] to [3]. [5] The second thermoplastic resin (B) is a polyolefin modified with maleic acid or maleic anhydride. The fiber-reinforced resin composition according to any one of [1] to [4]. [6] In the fiber-reinforced resin composition, the content of the acid or its derivative used for the acid modification of the second thermoplastic resin (B) is 0.01% by mass or more and 1.00% by mass or less relative to the total mass of the resin components. The fiber-reinforced resin composition according to any one of [1] to [5]. [7] The acid or its derivative used for the acid modification is maleic acid or maleic anhydride. The fiber-reinforced resin composition according to any one of [1] to [6]. [8] The first thermoplastic resin (A) contains a non-acid-modified polyolefin, the second thermoplastic resin (B) contains an acid-modified polyolefin, In the fiber-reinforced resin composition, the mass ratio of the acid or its derivative used for the acid modification of the second thermoplastic resin (B) to the polyolefin is 0.03 or more and 3.00 or less. The fiber-reinforced resin composition according to any one of [1] to [7]. [9] The fiber-reinforced resin composition has a content ratio of the second thermoplastic resin (B) of 0.1% by mass or more and 20% by mass or less relative to the total mass of the resin components. The fiber-reinforced resin composition according to any one of [1] to [8].

[10] The first thermoplastic resin (A) comprises a polyolefin that is not acid-modified. The fiber-reinforced resin composition according to any one of [1] to [9].

[11] The first thermoplastic resin (A) comprises a polyamide. The fiber-reinforced resin composition according to any one of [1] to

[10] .

[12] The carbon fiber (C) has the interfacial resin layer formed in 50% or more of the interface with the matrix. The fiber-reinforced resin composition according to any one of [1] to

[11] .

[0008] Another aspect of the present invention for solving the above problems relates to the following molded article

[13] .

[13] A molded article obtained by molding the fiber-reinforced resin composition according to any one of [1] to

[13] . [Effects of the Invention]

[0009] According to the present invention, there are provided a fiber-reinforced resin composition that can give a molded article having high impact resistance, and a molded article obtained by molding the fiber-reinforced resin composition. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1. Fiber-reinforced resin composition One embodiment of the present invention relates to a fiber-reinforced resin composition comprising a first thermoplastic resin (A), a second thermoplastic resin (B), and carbon fibers (C). The fiber-reinforced resin composition contains carbon fibers in a resin matrix. In this specification, the first thermoplastic resin (A) and the second thermoplastic resin (B) are collectively referred to as the resin component.

[0011] 1-1. First thermoplastic resin (A) The first thermoplastic resin (A) is a resin that impregnates the carbon fibers (C) and constitutes the matrix of the fiber-reinforced resin composition. The first thermoplastic resin (A) may be one type of resin or may contain two or more types of resins.

[0012] The type of the first thermoplastic resin (A) is not limited. Examples of the first thermoplastic resin (A) include polyolefins such as low-density, medium-density, and high-density polyethylene, ultra-high molecular weight polyethylene, high-pressure low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene, poly-1-butene, poly-4-methyl-1-pentene, poly-3-methyl-1-butene, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, 1-butene-α-olefin copolymer, and cyclic olefin copolymer; styrene-based elastomers, ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-methacrylic acid acrylate copolymers, ethylene-acrylic acid acrylate copolymers, ionomers, fluorine-based resins, rosin-based resins, terpene-based resins, and petroleum resins; polyvinyl chloride, chlorinated polyethylene, chlorinated polypropylene, polystyrene, styrene-acrylonitrile copolymers, polyolefins, styrene-acrylonitrile copolymers, and polyolefins. Examples of the polymerizable polymer include triacrylonitrile, polyethylene terephthalate, polybutylene terephthalate, polycyclohexanedimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polylactic acid, polycaprolactone, polybutylene succinate, polyamino acids, polydimethylsiloxane, polytetramethylene glycol, polyhydroxyethyl methacrylate, polyphenylene terephthalamide, polyacrylamide, polyurethane, polyamide, polyoxymethylene, polycarbonate, polyphenylene ether, polyphenylene sulfide, polysulfone, polyether ether ketone, polyether ketone, polyethylene oxide, polymethyl methacrylate, polyimide, liquid crystal polymer, polyamideimide, polyaminobismaleimide, polyarylate, polyetherimide, polyketone, polybenzimidazole, silicone resin, polybutadiene, ABS resin, ACS resin, AES resin, ASA resin, and cellulose resin. Among these, polyolefin and polyamide are preferred, and polyolefin is more preferred. The polyolefin may also be used in combination with a polyamide.These thermoplastic resin materials may be derived from fossil fuels, may be derived from biomass raw materials, or may be a mixture of these.

[0013] The first thermoplastic resin (A) may also contain a thermoplastic elastomer, such as a styrene-based thermoplastic elastomer, such as styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), styrene-ethylene / butylene-styrene copolymer (SEBS), or styrene-ethylene / propylene-styrene copolymer (SEPS). These thermoplastic elastomers may be derived from fossil fuels, biomass materials, or mixtures thereof. When the first thermoplastic resin (A) contains a thermoplastic elastomer, the content of the thermoplastic elastomer is preferably greater than 0% by mass and less than 20% by mass, more preferably greater than 0% by mass and less than 10% by mass, and even more preferably greater than 0% by mass and less than 5% by mass, based on the total mass of the first thermoplastic resin (A).

[0014] Furthermore, from the viewpoint of not localizing the first thermoplastic resin around the carbon fibers (C) but dispersing it widely throughout the matrix, it is preferable that the first thermoplastic resin is a resin that does not have acidic groups, and more specifically, it is preferable that the content of acidic groups such as hydroxyl groups and carboxyl groups relative to the total mass of the first thermoplastic resin is less than 0.1 mass%.

[0015] 1-1-1. Polyolefin (A1) The polyolefin (A1) is preferably an unmodified polyolefin.

[0016] The type of polyolefin (A1) is not limited, and a wide variety of polymers, such as α-olefins, cyclic olefins, non-conjugated dienes, and aromatic olefins, can be used. Among these, polymers containing α-olefins as the main component are preferred. The polymer containing α-olefins as the main component means a polymer in which the proportion of structural units derived from α-olefins relative to all structural units constituting the polymer is 50 mol% or more and 100 mol% or less. The proportion of structural units derived from α-olefins relative to all structural units constituting the polyolefin (A1) is preferably 60 mol% or more and 100 mol% or less, more preferably 70 mol% or more and 100 mol% or less. The proportion of each structural unit constituting the polyolefin (A1) is 13 The carbon content can be measured by C-NMR. The monomer constituting the polyolefin (A1) may be derived from a fossil fuel, may be derived from a biomass raw material, or may be a mixture thereof.

[0017] The α-olefin preferably has 2 or more and 20 or less carbon atoms, more preferably 2 or more and 10 or less carbon atoms, and even more preferably 2 or more and 8 or less carbon atoms. Examples of such α-olefins include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 3-methyl-1-butene, and 4-methyl-1-pentene. These α-olefins may be used alone, or two or more types may be used in combination to form a copolymer.

[0018] Examples of polyolefins (A1) include polyethylenes, which are ethylene homopolymers or copolymers of ethylene and other α-olefins, and polypropylenes, which are propylene homopolymers or copolymers of propylene and other α-olefins. The ratio of ethylene-derived structural units to all structural units and the ratio of propylene-derived structural units to all structural units in these polyethylenes and polypropylenes are preferably 50 mol% or more and 100 mol% or less, more preferably 70 mol% or more and 100 mol% or less, and even more preferably 90 mol% or more and 100 mol% or less. As polyolefins (A1), only one of these polyolefins may be used, or two or more may be used in combination.

[0019] The polyolefin (A1) is preferably polypropylene, more preferably propylene homopolymer, from the viewpoint of improving mechanical properties, heat resistance, and water resistance.

[0020] The polypropylene preferably has a melting point of 130°C or higher and 180°C or lower, more preferably 140°C or higher and 170°C or lower, as measured by a differential scanning calorimeter (DSC) at a temperature rise rate of 10°C / min.

[0021] From the viewpoint of improving the impregnation property into the carbon fiber (C), the polyolefin (A1) preferably has a melt flow rate (MFR) measured under a load of 2.16 kg in accordance with JIS K 7210 of 0.01 g / 10 min to 300 g / 10 min, more preferably 0.1 g / 10 min to 300 g / 10 min, even more preferably 1 g / 10 min to 300 g / 10 min, still more preferably 10 g / 10 min to 300 g / 10 min, and particularly preferably 50 g / 10 min to 300 g / 10 min. The MFR is a value measured at 190°C for polyethylene and at 230°C for polypropylene.

[0022] The polyolefin (A1) has a melt viscosity η at 250°C and a shear rate of 120 / sec in order to enhance the impregnation property into the carbon fiber (C). A The viscosity is preferably 30 Pa·s or more and 160 Pa·s or less, and more preferably 30 Pa·s or more and 100 Pa·s or less.

[0023] 1-1-2. Polyamide (A2) The polyamide (A2) can make it difficult for a molded article formed from the fiber-reinforced resin composition to deform over time due to load, for example, the polyamide (A2) can reduce the tensile creep strain of a molded article formed from the fiber-reinforced resin composition.

[0024] The type of polyamide (A2) is not limited, and a wide variety of compounds having amino and carboxy groups in the molecule (amino acid monomers) or polymers of dehydration condensates thereof, copolymers of diamines and dicarboxylic acids, and copolymers thereof can be used. The monomers constituting polyamide (A2) may be derived from fossil fuels, biomass raw materials, or a mixture thereof.

[0025] The polyamide (A2) preferably has a structural unit derived from a monomer having 10 or more carbon atoms. This increases the affinity between the polyolefin (A1) and the polyamide (A2), making it less likely that interfacial peeling will occur between them. From the above viewpoint, the polyamide (A2) preferably has a structural unit derived from a monomer having a linear or branched alkyl group having 10 or more carbon atoms, and more preferably has a structural unit derived from a monomer having a linear alkyl group having 10 or more carbon atoms.

[0026] Furthermore, in the polyamide (A2), the proportion of the structural units derived from the above-mentioned monomers having 10 or more carbon atoms relative to all structural units constituting the polyamide (A2) is preferably 60 mol% or more and 100 mol% or less, more preferably 70 mol% or more and 100 mol% or less, and even more preferably 90 mol% or more and 100 mol% or less.

[0027] Examples of the amino acid monomer having 10 or more carbon atoms include amino acids such as aminoundecanoic acid and aminododecanoic acid, and lactams such as undecane lactam and ω-lauryllactam. These amino acid monomers may be used alone or in combination to form a copolymer of two or more types.

[0028] Examples of the diamine, which is a monomer having 10 or more carbon atoms, include aliphatic diamines such as 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,13-diaminotridecane, 1,14-diaminotetradecane, 1,15-diaminopentadecane, 1,16-diaminohexadecane, 1,17-diaminoheptadecane, 1,18-diaminooctadecane, 1,19-diaminononadecane, and 1,20-diaminoeicosane, as well as alicyclic diamines such as bis(4-aminocyclohexyl)methane. These diamines may be used alone, or two or more may be used in combination to form a copolymer.

[0029] Examples of the dicarboxylic acid monomer having 10 or more carbon atoms include aliphatic dicarboxylic acids such as sebacic acid, undecanedioic acid, dodecanedioic acid, brassicic acid, tetradecanedioic acid, pentadecanedioic acid, and octadecanedioic acid, as well as aromatic dicarboxylic acids such as naphthalenedicarboxylic acid. These dicarboxylic acids may be used alone or in combination to form a copolymer of two or more types.

[0030] The polyamide (A2) may be a copolymer of these monomers having 10 or more carbon atoms with a monomer having 9 or less carbon atoms. Examples of amino acid monomers having 9 or less carbon atoms include amino acids such as aminocaproic acid and paraaminomethylbenzoic acid, and lactams such as ε-caprolactam. Examples of diamines having 9 or less carbon atoms include aliphatic diamines such as ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 2-methyl-1,5-diaminopentane (2M-5), and 2-methyl-1,8-diaminooctane (2M-8), alicyclic diamines such as cyclohexanediamine, and aromatic diamines such as p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, and m-xylylenediamine. Examples of dicarboxylic acids that are monomers having 9 or less carbon atoms include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and azelaic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, and isophthalic acid. These monomers having 9 or less carbon atoms may be used alone or in combination of two or more.

[0031] Specific examples of polyamides having structural units derived from monomers having 10 or more carbon atoms include polyamide 6 / 10, polyamide 6 / 12, polyamide 6 / 14, polyamide 11, polyamide 12, polyamide 10 / 10, polyamide 10 / 12, polyamide 10 / T, etc. Of these, polyamide 12 is preferred from the viewpoint of improving the water resistance of molded articles. These polyamides may be used alone or in combination of two or more.

[0032] The polyamide (A2) may also be other polyamides such as polyamide 6, polyamide 66, polyamide 6T, polyamide 6I, polyamide 9T, polyamide M5T, polyamide MXD6, polyamide 6T / 66, polyamide 6T / 6I, polyamide 6T / 6I / 66, polyamide 6T / 2M-5T, and polyamide 9T / 2M-8T. These polyamides may also be used in combination with polyamides having structural units derived from monomers having 10 or more carbon atoms. When used in combination, the content of the polyamide having structural units derived from monomers having 10 or more carbon atoms relative to the total mass of polyamide (A2) is preferably 50% by mass or more but less than 100% by mass, more preferably 70% by mass or more but less than 100% by mass, and even more preferably 90% by mass or more but less than 100% by mass.

[0033] From the viewpoint of improving the impregnation ability of the polyamide (A2) into the carbon fiber (C), the melt flow rate (MFR) measured under a load of 2.16 kg in accordance with JIS K 7210 is preferably 1 g / 10 min to 500 g / 10 min, more preferably 5 g / 10 min to 500 g / 10 min, even more preferably 10 g / 10 min to 300 g / 10 min, still more preferably 20 g / 10 min to 300 g / 10 min, and particularly preferably 60 g / 10 min to 100 g / 10 min. For PA12, the MFR is a value measured at 230°C.

[0034] From the viewpoint of improving the impregnation property into the carbon fiber (C), the polyamide (A2) preferably has a melting point of 160°C or more and 260°C or less, more preferably 170°C or more and 220°C or less, as measured by a differential scanning calorimeter (DSC) at a heating rate of 10°C / min.

[0035] 1-2. Second thermoplastic resin (B) The second thermoplastic resin (B) is a resin different from the first thermoplastic resin (A) that has been acid-modified with an acid or its derivative, and is a resin for forming an interfacial resin layer at the interface between the carbon fiber (C) and the matrix. In this embodiment, the second thermoplastic resin (B) forms an interfacial resin layer, which is thought to increase the adhesive strength between the matrix (more specifically, the first thermoplastic resin (A)) and the carbon fiber (C), thereby increasing the impact resistance of the molded body.

[0036] From the viewpoint of facilitating the formation of an interfacial resin layer around the carbon fibers (C), the second thermoplastic resin (B) is preferably a resin having a high affinity for the carbon fibers (C), and more specifically, is more preferably a resin having functional groups such as hydroxyl groups and carboxyl groups as acidic groups.

[0037] In addition, from the viewpoint of improving the adhesion between the interfacial resin layer and the matrix and improving the impact resistance of the molded article, it is preferable that the second thermoplastic resin (B) is the same type of resin as the first thermoplastic resin (A). For example, when the first thermoplastic resin (A) contains a polyolefin, it is preferable that the second thermoplastic resin (B) is an acid-modified polyolefin (B1). Only one type of acid-modified polyolefin (B1) may be used, or two or more types may be used in combination. The monomer constituting the acid-modified polyolefin (B1) may be derived from a fossil fuel, may be derived from a biomass raw material, or may be a mixture thereof.

[0038] In particular, when the first thermoplastic resin (A) contains a polyolefin (A1) and a polyamide (A2), the acid-modified polyolefin (B1) improves the interaction between the polyolefin (A1) and the polyamide (A2) and enhances the dispersibility of the polyamide (A2) in the polyolefin (A1), thereby enabling the acid-modified polyolefin (B1) to further increase the mechanical strength of the molded article and improve the heat distortion resistance of the molded article.

[0039] The acid-modified polyolefin (B1) is preferably a resin obtained by modifying an unmodified polyolefin with an unsaturated carboxylic acid or a derivative thereof.

[0040] The unmodified polyolefin may be any of the various polyolefins exemplified as polyolefin (A1). In this case, it is preferable that the polyolefin (A1) and the unmodified polyolefin used as the raw material for the acid-modified polyolefin (B1) are the same type of resin. For example, when the polyolefin (A1) is polyethylene, the unmodified polyolefin used as the raw material for the acid-modified polyolefin (B1) is also preferably polyethylene, and when the polyolefin (A1) is polypropylene, the unmodified polyolefin used as the raw material for the acid-modified polyolefin (B1) is also preferably polypropylene. These unmodified polyolefins may be used alone or in combination of two or more.

[0041] Examples of unsaturated carboxylic acids used for the modification include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, sorbic acid, and angelic acid, and unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, tetrahydrophthalic acid, norbornene dicarboxylic acid, and bicyclo[2.2.1]hept-2-ene-5,6-dicarboxylic acid.

[0042] Examples of the unsaturated carboxylic acid derivatives used for modification include acid anhydrides, acid halides, esters, amidates, imides, and metal salts of the above-mentioned unsaturated carboxylic acids. Specific examples of the unsaturated carboxylic acid derivatives include unsaturated dicarboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, and bicyclo[2.2.1]hept-2-ene-5,6-dicarboxylic anhydride; unsaturated dicarboxylic acid halides such as malenyl chloride; acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate; methacrylic acid esters such as methyl methacrylate and glycidyl methacrylate; maleic acid esters such as monomethyl maleate, monoethyl maleate, dimethyl maleate, and diethyl maleate; other esters such as diethyl fumarate, dimethyl itaconate, diethyl citraconic acid, dimethyl tetrahydrophthalate, and dimethyl bicyclo[2.2.1]hept-2-ene-5,6-dicarboxylate; acrylamide, maleic acid amide, maleimide, sodium acrylate; and sodium methacrylate.

[0043] Among these, from the viewpoint of increasing the thickness of the interfacial resin layer, unsaturated dicarboxylic acids or derivatives thereof are preferred, unsaturated dicarboxylic acids or anhydrides thereof are more preferred, and maleic acid or maleic anhydride is even more preferred. Alternatively, they may be modified by combining an acrylic acid ester with glycidyl methacrylate. These unsaturated carboxylic acids or derivatives thereof may be used alone or in combination of two or more.

[0044] The acid-modified polyolefin (B1) may have an unsaturated dicarboxylic acid or a derivative thereof grafted to a side chain, or may have an unsaturated dicarboxylic acid or a derivative thereof copolymerized in the main chain.

[0045] In the acid-modified polyolefin (B1), the proportion of structural units derived from unsaturated carboxylic acids or their derivatives is preferably 0.1% by mass or more and 5% by mass or less, more preferably 0.2% by mass or more and 1% by mass or less, based on the total mass of the acid-modified polyolefin (B1). The proportion of structural units derived from unsaturated carboxylic acids or their derivatives can be measured by infrared absorption spectroscopy or the like.

[0046] 1-3. Carbon fiber (C) The type of carbon fiber (C) is not limited, and may be any carbon fiber such as polyacrylonitrile-based, rayon-based, pitch-based, polyvinyl alcohol-based, regenerated cellulose-based, or pitch-based produced from mesophase pitch. The carbon fiber may be a general-purpose fiber or a high-strength fiber. The carbon fiber may also be a recycled fiber. A plurality of carbon fibers may be bundled together with a sizing agent. Only one of these carbon fibers (C) may be used, or two or more types may be used in combination.

[0047] The carbon fibers (C) may be short fibers having an average fiber length of less than 1.0 mm, or long fibers having an average fiber length of 1.0 mm or more. When the carbon fibers (C) are short fibers, they may be chopped fibers (cut fibers) without fibrils (microfibers split in the axial direction and divided into smaller pieces), or pulp-like fibers having fibrils. The carbon fibers (C) may be single fibers or twisted yarns formed by twisting together a plurality of single fibers.

[0048] The average fiber length of the carbon fibers (C) is preferably 0.01 mm or more and 100 mm or less, more preferably 0.1 mm or more and 50 mm or less, and even more preferably 1 mm or more and 30 mm or less. When the average fiber length is within the above range, the mechanical strength of the molded product is easily increased, and from the viewpoint of suppressing the generation of dry fibers due to the detachment of relatively short reinforcing fibers from the fiber-reinforced resin composition, it is preferable that the ratio of the number of reinforcing fibers having a fiber length of less than 0.1 mm to the number of all reinforcing fibers in the carbon fibers (C) is 18% or less.

[0049] The average fiber diameter of the carbon fibers (C) is preferably 1 μm or more and 30 μm or less, more preferably 5 μm or more and 20 μm or less. When the average fiber diameter is within the above range, the mechanical strength (particularly impact resistance and rigidity) and heat resistance of the molded article are easily increased, and the appearance of the molded article is improved. Furthermore, when the average fiber diameter is within the above range, the carbon fibers (C) are easily impregnated with a resin component.

[0050] The average fiber length and average fiber diameter can be determined, for example, by measuring the lengths or diameters of 100 carbon fibers (C) randomly selected from a photograph of carbon fibers (C) taken with an optical microscope, and then calculating the arithmetic mean.

[0051] From the viewpoint of facilitating the formation of the interfacial resin layer and increasing its thickness, the carbon fiber (C) preferably has a large amount of oxygen atoms (O) present on the surface, and also has a large amount of hydroxyl groups (OH) present on the surface.

[0052] Specifically, the carbon fiber (C) preferably has a ratio [O / C] of the number of oxygen (O) atoms to the total number of oxygen atoms (O) and carbon atoms (C) on the surface of 15.00 or more and 60.00 or less, more preferably 25.00 or more and 50.00 or less, and even more preferably 35.00 or more and 45.00 or less.

[0053] Furthermore, the carbon fiber (C) has a surface ratio of hydroxyl groups to the total amount of carbon atoms (C), hydroxyl groups (OH), and carboxyl groups (COOH) [OH / (C+OH+COOH)] of preferably 30.00% or more and 80.00% or less, more preferably 35.00% or more and 78.00% or less, even more preferably 45.00% or more and 75.00% or less, and particularly preferably 60.00% or more and 73.00% or less.

[0054] The number of atoms and the amount of functional groups on the surface of the carbon fiber (C) can be measured by X-ray photomolecular spectroscopy (XPS).

[0055] The number of atoms and the amount of functional groups on the surface of the carbon fiber (C) are not particularly limited. For example, by treating the surface of the carbon fiber with an alkali, the amount of oxygen atoms (O) present on the surface can be increased, or the amount of hydroxyl groups (OH) present on the surface can be increased.

[0056] The carbon fibers (C) may be bundled with a sizing agent. The sizing agent may be any of polyolefin-based sizing agents, urethane-based sizing agents, polyamide-based sizing agents, and epoxy-based sizing agents. Among these, polyolefin-based sizing agents, polyamide-based sizing agents, and epoxy-based sizing agents are preferred from the viewpoint of improving the flexural modulus, flexural strength, and impact resistance of the molded article.

[0057] The mass ratio (ignition loss) of the sizing agent to the carbon fibers (C) is preferably 0.1 mass % or more and 4.0 mass % or less.

[0058] 1-4.Other ingredients The fiber-reinforced resin composition may contain components other than the above-mentioned components (A) to (C). Examples of other components include thermosetting resins, flame retardants, flame retardant auxiliaries, fillers, colorants, antibacterial agents, and antistatic agents. These components may be used alone or in combination of two or more.

[0059] Examples of the flame retardant include halogen-based flame retardants such as halogenated aromatic compounds, phosphorus-based flame retardants such as nitrogen-containing phosphate compounds and phosphoric acid esters, nitrogen-based flame retardants such as guanidine, triazine, melamine and derivatives thereof, inorganic flame retardants such as metal hydroxides, boron-based flame retardants, silicone-based flame retardants, sulfur-based flame retardants, and red phosphorus-based flame retardants.

[0060] Examples of the flame retardant synergist include antimony compounds, metal compounds containing zinc, metal compounds containing bismuth, magnesium hydroxide, and clay silicates.

[0061] Examples of fillers include glass components such as glass beads and glass flakes, silica compounds such as silica, graphite, calcium silicate, aluminum silicate, kaolin, talc, and clay, metal oxides such as iron oxide, titanium oxide, zinc oxide, antimony oxide, and alumina, calcium, magnesium, and metal carbonates or sulfates.

[0062] Examples of colorants include pigments and dyes.

[0063] 1-5. Content of each ingredient The fiber-reinforced resin composition preferably contains 40% by mass or more and 95% by mass or less of the resin component relative to the total amount of the resin components (first thermoplastic resin (A) and second thermoplastic resin (B)) and carbon fiber (C), more preferably 45% by mass or more and 85% by mass or less, and even more preferably 50% by mass or more and 75% by mass or less. The higher the content of the resin component, the easier it is to make the molded body lighter.

[0064] The fiber-reinforced resin composition preferably contains 5% by mass or more and 60% by mass or less of the carbon fibers (C) relative to the total amount of the resin component and the carbon fibers (C). The higher the content of the carbon fibers (C), the easier it is to increase the mechanical strength of the molded product, such as the flexural modulus, flexural strength, tensile modulus, and tensile strength.

[0065] When the first thermoplastic resin (A) contains a polyolefin (A1) and a polyamide (A2), the fiber-reinforced resin composition preferably contains 60% by mass or more and 99% by mass or less of the polyolefin (A1) relative to the total mass of the first thermoplastic resin (A). The greater the amount of polyolefin (A1), the easier it is to make the molded body lighter.

[0066] When the first thermoplastic resin (A) contains a polyolefin (A1) and a polyamide (A2), the fiber-reinforced resin composition preferably contains 1% by mass or more and 40% by mass or less of the polyamide (A2) relative to the total mass of the first thermoplastic resin (A). The higher the content of polyamide (A2), the easier it is to improve the heat resistance of the molded product.

[0067] The fiber-reinforced resin composition preferably contains 80% by mass or more and 99.9% by mass or less of the first thermoplastic resin (A) relative to the total mass of the resin components, more preferably 80% by mass or more and 99% by mass or less, more preferably 80% by mass or more and 95% by mass or less, and particularly preferably 80% by mass or more and 90% by mass or less. The higher the content of the first thermoplastic resin (A), the less likely the viscosity of the fiber-reinforced resin composition to decrease, and the more improved the moldability.

[0068] The fiber-reinforced resin composition preferably contains 0.1% by mass or more and 20% by mass or less of the second thermoplastic resin (B), preferably 1% by mass or more and 20% by mass or less, more preferably 5% by mass or more and 20% by mass or less, and most preferably 10% by mass or more and 20% by mass or less, based on the total mass of the resin components. Increasing the content of the second thermoplastic resin (B) facilitates the formation of a uniform and homogeneous interfacial resin layer around the carbon fibers, thereby enhancing the impact resistance of the molded article. Furthermore, increasing the content of the second thermoplastic resin (B) enhances the impregnation of the resin component into the carbon fibers (C), thereby reducing the risk of exposure of the carbon fibers (C) on the surface of the molded article and the retention (bridging) of the fiber-reinforced resin composition during injection molding. Furthermore, increasing the content of the second thermoplastic resin (B) enhances the adhesion between the resin component and the carbon fibers (C), thereby enhancing the mechanical strength of the molded article.

[0069] 1-6.Interfacial resin layer The fiber-reinforced resin composition has an interfacial resin layer between the matrix and the carbon fibers (C), which has properties (hardness, etc.) different from those of the matrix. The interfacial resin layer is a layer formed by adding the second thermoplastic resin (B) to the resin component, and is probably a layer formed by the second thermoplastic resin (B) being adsorbed onto the carbon fibers.

[0070] The interface resin layer may be a layer consisting of only the second thermoplastic resin (B), or may be contained as part of the first thermoplastic resin (A). The second thermoplastic resin (B) may be entirely contained as the interface resin layer, or may be partly contained in the matrix.

[0071] The presence of an interfacial resin layer can be confirmed by a phase image obtained using an atomic force microscope (AFM). Specifically, 15 observation areas measuring 2 μm × 1 μm are set near the interface between the carbon fiber (C) and the matrix in a cross section of a fiber-reinforced resin composition containing carbon fibers. For each observation area, a 500-nm line analysis is performed from the carbon fiber to the matrix. Based on the measured phase change, the change in hardness along the measurement line is quantified, and a graph (waveform diagram) is obtained showing the cantilever angle at that measurement position relative to the measurement position on the measurement line. This waveform diagram reveals a peak at the boundary between the carbon fiber (C) and the matrix, where the difference in cantilever angle significantly changes. This peak is due to the addition of the second thermoplastic resin (B) to the resin component, and is therefore thought to represent an interfacial resin layer formed by the second thermoplastic resin (B). Therefore, the waveform diagram is differentiated to determine the slope of the waveform for each measurement position, and the distance from the point on the measurement line where the slope changes from positive to negative, indicating the start point of the interface resin layer, to the point where the slope changes from positive to negative, indicating the end point of the interface resin layer, after the slope changes from negative to positive at the apex of the peak, is determined to be the thickness of the interface resin layer.

[0072] The interfacial resin layer does not necessarily occur uniformly around the carbon fiber (C). In other words, there may be areas around the carbon fiber (C) where the interfacial resin layer occurs and areas where the interfacial resin layer does not occur. Therefore, a 2 μm × 1 μm observation area near the interface between the carbon fiber (C) and the matrix when the second thermoplastic resin (B) is not added to the resin component is observed with an atomic force microscope (AFM) to obtain a phase image. The maximum angle difference (the difference between the minimum and maximum angles) of the cantilever angle near the boundary between the carbon fiber and the matrix is ​​then determined. Then, when the above measurement is performed on a fiber-reinforced resin composition that is expected to contain the second thermoplastic resin (B), if an angle difference greater than this angle difference occurs, the observation area is determined to be a region where the interfacial resin layer occurs.

[0073] The average thickness of the interfacial resin layer thus obtained in the region where the interfacial resin layer is formed is preferably 10.00 nm or more and 80.00 nm or less, more preferably 20.00 nm or more and 70.00 nm or less, even more preferably 30.00 nm or more and 60.00 nm or less, and particularly preferably 35.00 nm or more and 50.00 nm or less.

[0074] Furthermore, the ratio of the region where the interfacial resin layer is formed to the interface between the matrix and the carbon fibers (C) is preferably 30% or more and 100% or less, and more preferably 50% or more and 100% or less.

[0075] The average thickness of the interfacial resin layer can be determined by setting a measurement line at a predetermined number (for example, 15 locations), measuring the thickness of the interfacial resin layer as described above, and averaging the thicknesses of the interfacial resin layer obtained for the observation ranges determined to be the regions where the interfacial resin layer is formed. The proportion of the region where the interfacial resin layer is formed at the interface between the matrix and the carbon fiber (C) can be determined by setting a measurement line at a predetermined number (for example, 15 locations), measuring as described above, and calculating the proportion of the observation range where a cantilever angle difference greater than the maximum value when the second thermoplastic resin (B) is not added, relative to the number of measurements.

[0076] According to the findings of the present inventors, the greater the average thickness of the interfacial resin layer in a fiber-reinforced resin composition, the higher the impact resistance of the molded body. Furthermore, the greater the proportion of the region where the interfacial resin layer is formed at the interface between the matrix and the carbon fibers (C) in the fiber-reinforced resin composition, the higher the impact resistance of the molded body. In other words, the greater these values, the thicker the interfacial resin layer is formed around the carbon fibers (C), or the greater the area of ​​the periphery of the carbon fibers (C) where the interfacial resin layer is formed. It is believed that this interfacial resin layer enhances adhesion between the matrix and the carbon fibers (C). Therefore, the greater the above values, the stronger the interaction between the matrix and the carbon fibers (C), making it easier to absorb impact energy at the interface between the matrix and the carbon fibers (C) when an impact is applied, and the less likely the carbon fibers (C) are to slip out of the matrix. As a result, it is believed that the interfacial resin layer enhances the impact resistance of the molded body.

[0077] According to the findings of the present inventors, when the first thermoplastic resin (A) contains a non-polar resin, such as polyolefin, particularly polypropylene, it is possible to increase the average thickness of the interfacial resin layer and the proportion of the region where the interfacial resin layer is formed at the interface between the matrix and the carbon fibers (C). This is thought to be because the non-polar resin is less likely to gather around the carbon fibers (C), and therefore is less likely to inhibit the formation of the interfacial resin layer by the second thermoplastic resin (B).

[0078] From the viewpoint of increasing the average thickness of the interfacial resin layer and the proportion of the area where the interfacial resin layer is formed, the content of the acid or its derivative used for acid-modifying the second thermoplastic resin (B) in the resin component is preferably 0.01 mass% or more and 1.00 mass% or less, more preferably 0.03 mass% or more and 0.80 mass% or less, even more preferably 0.10 mass% or more and 0.60 mass% or less, and particularly preferably 0.30 mass% or more and 0.60 mass% or less.

[0079] Furthermore, from the viewpoint of increasing the average thickness of the interfacial resin layer and the proportion of the area where the interfacial resin layer is formed, the fiber-reinforced resin composition preferably has a mass ratio (acid component / polyolefin) of the acid or its derivative used in the acid-modification of the second thermoplastic resin to the polyolefin, calculated from the peak intensity ratio (acid group / olefin) of the acid group derived from the acid or its derivative used in the acid-modification of the second thermoplastic resin to the olefin component in the polyolefin (the unmodified polyolefin contained in the first thermoplastic resin (A) and the acid-modified polyolefin contained in the second thermoplastic resin (B)) in an infrared spectroscopy (IR) spectrum, of 0.03 or more and 3.00 or less, more preferably 0.05 or more and 2.50 or less, even more preferably 0.10 or more and 1.50 or less, and most preferably 0.50 or more and 1.00 or less.

[0080] The peak ratio can be measured by IR measurement. Specifically, polyolefin components (the unmodified polyolefin contained in the first thermoplastic resin (A) and the acid-modified polyolefin contained in the second thermoplastic resin (B)) are extracted from the fiber-reinforced resin composition using a solvent that dissolves olefins. This extract is then analyzed by infrared spectroscopy (IR), and the ratio of the peak intensity of the acidic group (for example, a carbonyl group if the second thermoplastic resin (B) is a maleic acid-modified resin) to the peak intensity of the olefin-derived structure (acidic group / olefin) is calculated. A mass ratio corresponding to the obtained peak ratio is obtained using a known calibration curve.

[0081] 1-7.Form The form of the fiber-reinforced resin composition is not particularly limited, and may be a composition in a molten state (fluid state) containing each heated and melted resin material, carbon fiber (C), and other components, or the resin material may be cooled and in a solid state such as pellets or sheets.

[0082] The carbon fibers (C) may be dispersed in a random orientation in the fiber-reinforced resin composition, or may be aligned in one direction. For example, the fiber-reinforced resin composition may be a thin-film fiber-reinforced resin (UD sheet) in which a resin component is impregnated into a plurality of carbon fibers (C) aligned in one direction, a thin-film fiber-reinforced resin (cross sheet) in which a resin component is impregnated into a woven fabric of a plurality of reinforcing fibers aligned in one direction, or a pellet-shaped resin composition (compound pellet) in which a resin component is impregnated into a plurality of carbon fibers (C) aligned in one direction or dispersed in one direction. Among these, compound pellets are preferred because they are applicable to injection molding and extrusion molding and have high moldability.

[0083] 2. Manufacturing method The fiber-reinforced resin composition may be prepared by melt-kneading the above-mentioned components, or by impregnating carbon fibers (C) oriented in one direction with a resin component and other components.

[0084] For example, when the carbon fibers (C) are short fibers, the above-mentioned components can be melt-kneaded to obtain a fiber-reinforced resin composition in which the carbon fibers (C) are dispersed and oriented in random directions. The melt-kneading temperature is preferably 5°C to 100°C higher than the melting point of the resin with the highest melting point among the resin components, and more preferably 10°C to 60°C higher. The melt-kneading time is preferably 15 seconds to 15 minutes, and more preferably 30 seconds to 10 minutes.

[0085] For example, the above-mentioned components may be melt-kneaded using a melt-kneader such as a roll mill, a Banbury mixer, or a kneader. Alternatively, the components may be dry-blended using a kneader such as a tumbler blender, a Henschel mixer, or a ribbon mixer, and then melt-kneaded and extruded using an extruder such as a single-screw extruder or a twin-screw extruder. The melt-kneaded fiber-reinforced resin composition in a molten state may be directly injected into a molding machine and molded, or the extruded fiber-reinforced resin composition may be processed into a predetermined shape (e.g., pellets) to form a solid fiber-reinforced resin composition.

[0086] When the carbon fibers (C) are long fibers, the carbon fibers (C) are oriented in one direction and then impregnated with a molten resin component and other components to produce a fiber-reinforced resin composition such as a UD sheet, a cross-seat, or an LFT. The temperature of the molten resin is preferably 5°C to 100°C higher, and more preferably 10°C to 60°C higher, than the melting point of the resin with the highest melting point among the resin components.

[0087] For example, carbon fibers (C) aligned in one direction can be made to travel through an impregnation roll or an impregnation die, and brought into contact with the molten resin component and other components in the impregnation roll or the impregnation die, thereby impregnating them. After impregnation, the resin component is cooled and solidified, and then processed into a predetermined shape (for example, a sheet or pellet) to obtain a solid fiber-reinforced resin composition.

[0088] 3.Applications The fiber-reinforced resin composition can be processed into a molded article by known molding methods such as injection molding, extrusion molding, press molding, etc. The above-mentioned ratios of the components, the average thickness of the interfacial resin layer, and the proportion of the region where the interfacial resin layer is formed are also carried over to the molded article.

[0089] The molded articles can be used in a wide range of applications, from household goods for daily necessities and recreational purposes to general industrial applications and industrial goods. Examples of applications of the molded articles include home appliance material parts, communication device parts, electrical parts, electronic parts, automobile parts, parts for vehicles other than automobiles, ships, aircraft materials, machine mechanism parts, building materials, civil engineering materials, agricultural materials, power tool parts, food containers, films, sheets, and fibers.

[0090] The improved heat resistance of the composite allows it to be used in powertrain components, mechanical components due to its improved tensile creep resistance, and exterior panel components due to its improved bending properties. Examples of the composite can also be used in other applications. Examples of the composite can include intake manifolds, oil pans, cylinder heads, cylinder head covers, engine covers, shrouds, mirror brackets, interior consoles, sunroofs, sunroof frames, front doors, back doors, sliding doors, front-end modules, door modules, fenders, wheel caps, gas tanks, belts, headliners, convertible tops, armrests, door trim, rear package trays, sun visors, wheel covers, mattress covers, airbags, insulation, wire coverings, electrical insulation, coverings, flooring, corner walls, deck panels, covers, plywood, ceiling panels, partition panels, side walls, wallpaper, wall coverings, exterior materials, interior materials, roofing materials, soundproofing panels, and heat insulation panels.

[0091] Examples of home appliance material parts, communication equipment parts, electrical parts, and electronic parts include battery pack parts (covers, trays, module cases), office and OA equipment such as printers, personal computers, word processors, keyboards, personal digital assistants (PDAs), headphone stereos, mobile phones, telephones, facsimiles, copiers, electronic cash registers (ECRs), calculators, electronic organizers, electronic dictionaries, cards, holders, and stationery; home appliances such as washing machines, refrigerators, vacuum cleaners, microwave ovens, lighting fixtures, game consoles, irons, and kotatsu tables; audio-visual equipment such as televisions, video players, cameras, video cameras, boomboxes, tape recorders, minidiscs, CD players, speakers, and liquid crystal displays; connectors, relays, capacitors, switches, printed circuit boards, coil bobbins, semiconductor encapsulating materials, electric wires, cables, transformers, deflection yokes, distribution boards, and clocks.

[0092] Examples of everyday items include plywood, synthetic fiberboard, buckets, containers, bags, cases, goggles, skis, snowboards, rackets, tents, bicycles, fishing tackle, and lifestyle and sporting goods such as musical instruments. [Example]

[0093] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to the descriptions in the examples.

[0094] 1. Prepare ingredients The following materials were prepared:

[0095] 1-1. First thermoplastic resin (A) PP: Unmodified polypropylene Prime Polymer J13B, MFR (JIS K72101-1:2014 compliant, 230°C, 2.16 kg load): 220 g / 10 min PA12: Polyamide 12 UBE Corporation 3012U, MFR (JIS K7210-1:2014 compliant, 200°C, 2.16 kg load): 26 g / 10 min

[0096] 1-2. Second thermoplastic resin (B) 97 parts by weight of unmodified polypropylene (Prime Polymer Co., Ltd., product name J106G, MFR (JIS K72101-1:2014, 230°C, 2.16 kg) = 15 g / 10 min) was premixed with 1 part by weight of dialkyl peroxide (NOF Corporation, Perhexa (Perhexa is a registered trademark of the company) 25B) and 3 parts by weight of powdered maleic anhydride (NOF Corporation, Crystal Man (Crystal Man is a registered trademark of the company)). This mixture was fed into a 30 mm diameter twin-screw extruder temperature-controlled at 190°C and melt-kneaded at 200 rpm. The resulting strand was cooled in a water bath to obtain maleic anhydride-modified polypropylene. To remove residual unmodified maleic anhydride, the maleic anhydride-modified polypropylene was vacuum-dried at 40°C for 2 hours to obtain maleic anhydride-modified polypropylene (PP-MAL). The maleic anhydride-modified polypropylene obtained had a maleic acid content of 3.0% by mass and an MFR (230° C., 2.16 kg) of 800 g / 10 min.

[0097] 1-3. Carbon fiber (C) CF1: Surface-treated long carbon fiber roving coated with epoxy sizing, Toray Industries, Inc., T700GC-31E (24,000 fibers, 7 μm filament diameter) CF2: Surface-treated long carbon fiber roving coated with epoxy sizing, Toray Industries, T700SC-50C (24,000 fibers, 7 μm filament diameter)

[0098] 1-2-1. Carbon fiber surface measurement The amount of atoms and functional groups on the surface of these carbon fibers was measured using an X-ray photomolecular spectroscopy (XPS) device (K-Alpha, manufactured by Thermo Fisher Scientific), and the ratio of the number of oxygen (O) atoms to the total number of oxygen atoms (O) and carbon atoms (C) [O / C], and the ratio of hydroxyl groups to the total number of carbon atoms (C), hydroxyl groups (OH), and carboxyl groups (COOH) [OH / (C+OH+COOH)] were calculated.

[0099] 2. Preparation of fiber-reinforced resin composition and test specimens 2-1. Composition 1 and Test Piece 1 (Example 1) 76 parts by mass of PP, 10 parts by mass of PA12, and 14 parts by mass of PP-MAL were placed in the hopper of a twin-screw melt-kneading extruder (manufactured by The Japan Steel Works, Ltd., TEX30α, L / D=53, D=30 mm) whose temperature was adjusted to 290°C, and melt-kneaded. The maleic acid content (referred to as the M value) in these resin components was 0.42% by mass.

[0100] CF1 was expanded and introduced into the impregnation die. The above-mentioned molten resin component was supplied to the impregnation die, and the above-mentioned resin component was impregnated into CF1 inside the impregnation die. The moving speed of CF1 at this time was adjusted so that the proportion of CF1 in the obtained fiber-reinforced resin composition was 42 mass%. Thereafter, the resin component impregnated into CF1 was cooled and solidified, and CF1 and the resin component were cut into pellets with a strand cutter to a length of 9 mm to obtain a pellet-shaped fiber-reinforced resin composition (composition 1).

[0101] Composition 1 was placed in an injection molding machine (manufactured by The Japan Steel Works, Ltd., J100ADS-180U) and injection molded at a set temperature of 250°C and a mold temperature of 60°C to prepare strip test pieces (length 80 mm x width 10 mm x thickness 4 mm) and dumbbell test pieces (compliant with JIS K7139:2009 (ISO 20753:2008)) for evaluation tests. These were designated as Test Pieces 1.

[0102] 2-2. Composition 2 and Test Piece 2 (Example 2) Composition 2 and Test Piece 2 were prepared in the same manner as in the preparation of Composition 1 and Test Piece 1, except that 88 parts by mass of PP, 10 parts by mass of PA12, and 2 parts by mass of PP-MAL were placed in the hopper of a twin-screw melt kneading extruder.

[0103] 2-3. Composition 3 and Test Piece 3 (Comparative Example 1) Composition 3 and test piece 3 were prepared in the same manner as composition 1 and test piece 1, except that CF2 was used instead of CF1 and the moving speed of CF2 was adjusted so that the proportion of CF2 in the resulting fiber-reinforced resin composition was 41 mass%.

[0104] 3. Evaluation The above test pieces were used to carry out the following evaluations.

[0105] 3-1. Infrared spectroscopy (IR) measurements 1) Sample preparation The measurement sample was pressed at 250°C for 3 minutes to prepare a pressed film with a thickness of 0.1 mm. The polyolefin components (PP and PP-MAL) were extracted from the test piece using xylene as a solvent to dissolve the olefin, and the extracted sample was used for infrared spectroscopy (IR) analysis. 2) Measurement conditions Measurement equipment: JASCO FT / IR4100 infrared spectrophotometer Resolution: 2cm -1 Accumulation count: 16 times 3) Calculation of peak intensity ratio The sample prepared in 1) was measured under the conditions in 2), and the peak derived from the carbonyl group (maleic acid) (1790 cm -1 ) and the peak due to the olefin (PP) main chain (4321 cm -1 ) and the IR peak intensities of the following IR peak intensity ratios were calculated: IR peak intensity ratio = carbonyl group-derived peak / olefin main chain-derived peak 4) Calculation of mass ratio Based on the peak intensity ratio obtained in 3), the mass ratio was calculated according to the following formula using a calibration curve (X-axis is mass ratio, Y-axis is a linear function of IR peak intensity ratio) previously prepared using a standard sample (a mixture of PP and succinic anhydride) with a known mass ratio. Mass ratio = acid component (maleic acid) / polyolefin (total amount of PP and PP-MAL)

[0106] 3-2. Bending test A bending test was performed at 23°C using dumbbell-shaped test specimens in accordance with JIS K7171:2022. The initial slope of the stress-strain curve obtained from the bending test at a test speed of 2 mm / min was used to determine the flexural modulus (GPa). The maximum stress in the stress-strain curve was used as the flexural strength (MPa).

[0107] 3-3. Charpy impact resistance test The dumbbell-shaped test specimen for evaluation test was processed into a shape (Type 1) with a V-shaped notch in accordance with JIS K7111-1:2012, and the impact resistance value (KJ / m) was measured at 23°C with a hammer capacity of 4J in accordance with the JIS K7111-1:2012·1eA standard. 2 ) was sought.

[0108] 3-4.Interfacial resin layer A cross section containing the carbon fiber of each composition was observed using an atomic force microscope (AFM) (Hitachi High-Tech Science Corporation, AFM5300E) to obtain an observation image (phase image) containing the resin component and carbon fiber. Fifteen observation areas measuring 2 μm × 1 μm were set near the interface between the carbon fiber and the matrix, and a 500 nm line analysis was performed for each observation area from the carbon fiber to the matrix. Based on the phase change, the change in hardness along the measurement line was quantified, and a graph (waveform diagram) was obtained showing the cantilever angle at each measurement position relative to the measurement position on the measurement line. The waveform diagram was then differentiated to determine the slope of the waveform for each measurement position. The distance from the point where the slope changes from positive to negative to the point where the slope changes from positive to negative was determined for the peak on the measurement line where the maximum cantilever angle difference was 4.137° or greater, and this was defined as the thickness of the interfacial resin layer.

[0109] When similar measurements were performed on a fiber-reinforced resin composition prepared in the same manner as Composition 1 without adding PP-MAL, the maximum cantilever angle difference near the boundary between the carbon fiber and the matrix was 4.137°. Therefore, for the phase obtained on each measurement line, the phase when the cantilever angle difference was greater than 4.137° was determined to be the measurement result for the area where the interfacial resin layer had formed. The average thickness of the interfacial resin layer for the area where the interfacial resin layer had formed was then calculated.

[0110] In addition, the proportion of the 15 observation areas that were determined to be areas where an interfacial resin layer had formed was calculated, and this was taken as the proportion of the area where an interfacial resin layer had formed at the interface between the carbon fiber and the matrix.

[0111] 4.Results Table 1 shows the composition of the fiber-reinforced resin composition and the evaluation results of the test specimens prepared in each experiment.

[0112] [Table 1]

[0113] As is clear from Table 1, fiber-cured resin compositions in which the average thickness of the interface resin layer formed by the second thermoplastic resin (B) was 10.00 nm or more and 80.00 nm or less provided molded articles with high impact resistance. [Industrial Applicability]

[0114] According to the present invention, a molded article having good impact resistance can be produced.

Claims

1. a first thermoplastic resin (A) constituting a matrix; a second thermoplastic resin (B) which is an acid-modified resin different from the first thermoplastic resin (A); Carbon fiber (C), The average thickness of the interfacial resin layer formed by the second thermoplastic resin (B) and present at the interface between the carbon fiber (C) and the matrix is ​​10.00 nm or more and 80.00 nm or less. Fiber-reinforced resin composition.

2. The carbon fiber (C) has a ratio [O / C] of the number of oxygen (O) atoms to the total amount of oxygen atoms (O) and carbon atoms (C) on the surface of the fiber (C) of 15.00 or more and 60.00 or less. The fiber-reinforced resin composition according to claim 1.

3. The carbon fiber (C) has a surface ratio of hydroxyl groups to the total amount of carbon atoms (C), hydroxyl groups (OH), and carboxyl groups (COOH) [OH / (C+OH+COOH)] of 30.00% or more and 80.00% or less. The fiber-reinforced resin composition according to claim 1.

4. The second thermoplastic resin (B) is an acid-modified polyolefin. The fiber-reinforced resin composition according to claim 1.

5. The second thermoplastic resin (B) is a polyolefin modified with maleic acid or maleic anhydride. The fiber-reinforced resin composition according to claim 1.

6. In the fiber reinforced resin composition, the content of the acid or its derivative used for acid modification of the second thermoplastic resin (B) relative to the total mass of the resin components is 0.01% by mass or more and 1.00% by mass or less, The fiber-reinforced resin composition according to claim 1.

7. The acid or its derivative used for the acid modification is maleic acid or maleic anhydride. The fiber-reinforced resin composition according to claim 6.

8. the first thermoplastic resin (A) contains a polyolefin that is not acid-modified, the second thermoplastic resin (B) contains an acid-modified polyolefin, The fiber reinforced resin composition has a mass ratio of the acid or its derivative used for acid modification of the second thermoplastic resin (B) to the polyolefin of 0.03 or more and 3.00 or less, The fiber-reinforced resin composition according to claim 1.

9. In the fiber reinforced resin composition, the content ratio of the second thermoplastic resin (B) to the total mass of the resin component is 0.1% by mass or more and 20% by mass or less, The fiber-reinforced resin composition according to claim 1.

10. The first thermoplastic resin (A) contains a polyolefin that is not acid-modified, The fiber-reinforced resin composition according to claim 1.

11. The first thermoplastic resin (A) includes a polyamide. The fiber-reinforced resin composition according to claim 1.

12. The carbon fiber (C) has the interfacial resin layer formed in 50% or more of the interface with the matrix. The fiber-reinforced resin composition according to claim 1.

13. A molded article obtained by molding the fiber reinforced resin composition according to any one of claims 1 to 12.

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