Thermoplastic resin composition and molded article

Abstract

To provide a thermoplastic resin composition containing recycled carbon fibers, which has excellent productivity and impact resistance even though the recycled carbon fibers are used, and to provide a compact.SOLUTION: A thermoplastic resin composition for carbon fiber reinforcement contains recycled carbon fibers (A) and a thermoplastic resin (B). In the recycled carbon fibers (A), an oxygen content is 5.0 mass% or more. The thermoplastic resin (B) has an average solubility parameter of 9-15 and contains at least one of acrylic resin (B1) and styrenic resin (B2), where the acrylic resin (B1) and / or styrenic resin (B2) has a glass transition temperature of 0°C or higher.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermoplastic resin composition containing recycled carbon fibers and a molded article using the same. [Background technology]

[0002] Carbon fiber reinforced plastics (hereinafter referred to as CFRP) reinforced with carbon fiber (hereinafter referred to as CF) are used in a wide range of industrial applications, including sporting goods and aircraft parts. Wind turbine rotor blades, which have traditionally used glass fiber composite materials, are now being replaced with lightweight, high-strength CFRP in order to achieve improved efficiency and larger size.

[0003] Used CFRP waste and scraps (prepreg, sheet molding compound, etc.) generated during the CFRP manufacturing process have traditionally been crushed and then disposed of in landfills, but a technology has been proposed to reuse them as recycled carbon fiber (hereinafter sometimes referred to as r-CF). Patent Document 1 discloses two methods for recovering r-CF: one in which CFPR is crushed into flakes and then dry distilled in a substantially non-oxidizing atmosphere at a temperature range of 300 to 1,000°C, and the other in which CFPR is dry distilled in a substantially non-oxidizing atmosphere at a temperature range of 300 to 1,000°C, and then dry distilled into flakes. Patent Document 2 also discloses a method for producing r-CF from carbon fiber reinforced plastic (CFRP) containing CF and a matrix resin, in which the carbon fiber reinforced resin is heated to pyrolyze the matrix resin, resulting in a heat-treated product with a resin residue content of 0.01 to 30.0% by mass, and the heat-treated product is then cut.

[0004] However, r-CF has poor compatibility with plastics, and even when trying to incorporate it into resin, extrusion is unstable. Therefore, recycled carbon fiber reinforced plastics (hereinafter sometimes referred to as r-CFRP) reinforced with r-CF have issues with productivity and mechanical strength.

[0005] To address these issues, Patent Document 3 discloses a resin composition obtained using a resin and recycled carbon fibers that have a fiber length variation coefficient of 20% or more and do not contain a sizing agent. However, the physical properties of the r-CFRP obtained using this technology are insufficient. Patent Document 4 also discloses a polyolefin resin composition containing recycled carbon fibers, a polyolefin resin, and a dispersant having a basic group. The recycled carbon fibers have an average fiber length of 0.05 to 15.0 mm, and the amount of recycled carbon fibers mixed is 1 to 50 mass% per 100 mass% of the thermoplastic resin composition. However, there is a market demand for the development of r-CFRPs with high physical properties using resins other than polyolefins. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 7-118440 [Patent Document 2] Japanese Patent Publication No. 2020-075493 [Patent Document 3] Japanese Patent Application Publication No. 2019-163354 [Patent Document 4] Japanese Patent Publication No. 2020-176244 Summary of the Invention [Problem to be solved by the invention]

[0007] In the manufacturing process of CFRP for automobiles and aircraft, where safety is a major concern, there is a large amount of scrap material from intermediate products. Since the lifespan of CFRP in machine parts is estimated to be about 20 years, CFRP waste will increase in the future. For this reason, there is a strong demand for the development of r-CFRP with excellent properties, which is made from recycled carbon fiber (hereinafter sometimes referred to as r-CF) recovered from CFRP waste.

[0008] The present invention has been made in view of the above background, and aims to provide a thermoplastic resin composition containing recycled carbon fiber and a molded article that are excellent in productivity and impact resistance, even when recycled carbon fiber is used. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have found that the problems of the present invention can be solved by the following aspects, and have thus completed the present invention. [1]: A thermoplastic resin composition for carbon fiber reinforcement containing recycled carbon fibers (A) and a thermoplastic resin (B), The oxygen content in the recycled carbon fiber (A) is 5.0% by mass or more, the thermoplastic resin (B) has an average solubility parameter of 9 to 15 and contains at least one of an acrylic resin and a styrene resin; The acrylic resin (B1) and the styrene resin (B2) have a glass transition temperature of 0°C or higher. Thermoplastic resin composition. (Note that the oxygen content is a value measured using an energy dispersive X-ray spectrometer attached to a scanning electron microscope (SEM) at an acceleration voltage of 15 kV and a field magnification of 3000 times.) The average solubility parameter is a value calculated by the following formula (1). Equation (1): SP value = √(Ev / v) = √(ΣΔei / ΣΔvi) (where Ev: evaporation energy (cal / mol), v: molar volume (cm 3 / mol), Δei: evaporation energy of each atom or atomic group, Δvi: molar volume of each atom or atomic group. [2]: The thermoplastic resin composition according to [1], characterized in that the intensity ratio I1 / I2 of the diffraction intensity I1 at a Bragg angle 2θ=25° and the diffraction intensity I2 at 2θ=44° observed by X-ray diffraction of the recycled carbon fiber (A) is less than 6. [3]: The bulk density of the recycled carbon fiber (A) is 0.03 to 1.0 g / cm 3 The thermoplastic resin composition according to [1] or [2], wherein (However, the bulk density is a value obtained in accordance with JIS K5101.) [4]: The thermoplastic resin composition according to any one of [1] to [3], wherein the thermoplastic resin (B) contains an acid-modified thermoplastic elastomer (b-1). [5]: A molded article obtained by molding the thermoplastic resin composition according to any one of [1] to [4]. [Effects of the Invention]

[0010] According to the present invention, even when recycled carbon fibers are used, the excellent effect of being able to provide a thermoplastic resin composition and a molded article containing recycled carbon fibers that are excellent in productivity and impact resistance can be achieved. DETAILED DESCRIPTION OF THE INVENTION

[0011] An example of an embodiment to which the present invention is applied will be described below. Note that other embodiments are also included in the scope of the present invention as long as they conform to the spirit of the present invention. Furthermore, in this specification, a numerical range specified using "to" includes the numerical values ​​written before and after "to". Furthermore, in this specification, recycled carbon fiber will be referred to as r-CF, and carbon fiber (i.e., non-recycled carbon fiber) will be referred to as CF, and recycled carbon fiber reinforced plastic will be referred to as r-CFRP, and carbon fiber reinforced plastic (i.e., non-recycled carbon fiber reinforced plastic) will be referred to as CFRP. "Film" and "sheet" will not be distinguished by thickness. In this specification, "(meth)acrylic" means "acrylic and / or methacrylic", and "(meth)acrylate" means "acrylate and / or methacrylate". Unless otherwise noted, the various components appearing in this specification may be used independently, either singly or in combination of two or more. The numerical values ​​specified in this specification are values ​​determined by the methods disclosed in the Examples.

[0012] 《Thermoplastic resin composition》 The carbon fiber reinforced thermoplastic resin composition (hereinafter referred to as "thermoplastic resin composition") of this embodiment contains recycled carbon fibers (A) (hereinafter also referred to as "r-CF(A)") and a thermoplastic resin (B). The r-CF(A) has an oxygen content of 5.0 mass% or more, and the thermoplastic resin (B) contains at least one of an acrylic resin (B1) and a styrene resin (B2) having a solubility parameter of 9 to 15 and a glass transition temperature of 0°C or higher.

[0013] As a result of extensive research, the inventors have found that by combining r-CF (A) having an oxygen content of 5.0 mass% or more with a thermoplastic resin (B) containing at least one of an acrylic resin (B1) and a styrene resin (B2) having a solubility parameter of 9 to 15 and a glass transition temperature of 0°C or higher, the compatibility of the resin and the recycled carbon fiber is significantly improved, and the adhesion between the resin and the recycled carbon fiber can be improved. The thermoplastic resin composition of this embodiment improves impact strength, productivity, and elastic modulus. Furthermore, the excellent compatibility between the resin and recycled carbon fiber can suppress deposits on the die of manufacturing equipment. By suppressing deposits, problems such as deposits being mixed into the product or deposits clogging the die holes, resulting in poor material discharge, can be suppressed, thereby improving productivity. Furthermore, the improved adhesion between the thermoplastic resin (B) and the r-CF (A) can increase the elastic modulus. As a result, it is expected that parts that have previously used metal materials can be replaced with r-CFRP, which has excellent lightweight properties. Each component is described in detail below.

[0014] <Recycled carbon fiber (A)> r-CF (recycled carbon fiber) is carbon fiber recovered by recycling CFRP (carbon fiber reinforced plastic) scraps or CFRP waste. CFRP, the raw material for r-CF, contains CF (carbon fiber) and a matrix resin, and includes not only molded products but also intermediate products before molding (prepreg, towpreg, sheet molding compound, stampable sheet, bulk molding compound, etc.). There are no particular limitations on the shape of the CFRP or the form of the CF contained therein. Thermosetting resins, thermoplastic resins, etc. are used as the matrix resin for CFRP.

[0015] The r-CF(A) of this embodiment has an oxygen content of 5.0% by mass or more. The oxygen content in this specification refers to a value obtained by measurement described in the Examples below. The contents of other elements can be determined by similar methods. As described above, r-CF(A) is a carbon fiber obtained by subjecting scraps, CFRP waste, etc. to heat treatment and / or heated steam treatment to pyrolyze (gasify, carbonize, etc.) the matrix resin. By adjusting the oxidizing atmosphere during the heating process, r-CF(A) with an oxygen content of 5.0% by mass or more can be obtained.

[0016] By combining r-CF (A) with a thermoplastic resin (B) having a solubility parameter of 9 to 15 (described below) and at least one of an acrylic resin and a styrene resin (excluding thermoplastic elastomers) and an oxygen content of 5.0% by mass or more, the mutual compatibility can be significantly improved. The upper limit of the oxygen content of r-CF (A) is preferably 20.0% by mass or less, from the viewpoint of maintaining good strength of the thermoplastic resin composition. A more preferred range is 5.0 to 15.0% by mass.

[0017] The carbon content of r-CF(A) is set to 95.0 mass% or less. From the viewpoint of maintaining good strength of the thermoplastic resin composition containing r-CF(A), the lower limit of the carbon content of r-CF(A) is preferably set to 80 mass% or more. Note that r-CF(A) may contain other elements such as nitrogen, silicon, sodium, and sulfur as long as the effects of the present invention are not affected.

[0018] The fiber length of r-CF(A) is preferably 0.05 mm or more from the viewpoint of improving impact resistance and elastic modulus. Although there is no particular upper limit, a length of 20 mm or less is preferable in consideration of availability.

[0019] Commercially available r-CF(A) products include, for example, the CARBISO MF series (average fiber length 0.08 to 0.1 mm, oxygen content 6%) and the CARBISO C series (average fiber length 3 to 10 mm, oxygen content 5%).

[0020] From the viewpoint of improving the adhesion between the r-CF (A) and the thermoplastic resin (B), it is preferable that the intensity ratio I1 / I2 between the diffraction intensity I1 at a Bragg angle 2θ=25° and the diffraction intensity I2 at 2θ=44° observed by X-ray diffraction of the r-CF (A) is less than 6. -2θ=25° in CF(A) represents diffraction from the (002) plane, and 44° represents diffraction from the (10) plane.

[0021] In the heat treatment step in the recycling production process from CFRP, an oxidizing atmosphere is used, generating oxygen-derived functional groups on a portion of the surface of the r-CF(A). The introduction of these oxygen-derived functional groups reduces the diffraction intensity of the (002) plane of the r-CF(A). By reducing the diffraction intensity of the (002) plane of the r-CF(A), adhesion to the thermoplastic resin (B) can be improved. Meanwhile, considering the mechanical strength of the resulting thermoplastic resin composition, it is desirable that the diffraction intensity of the (10) plane of the r-CF(A) be as high as possible. The lower limit of the intensity ratio I1 / I2 is preferably 3 or greater, from the viewpoint of achieving excellent mechanical strength in the resulting thermoplastic resin composition. The intensity ratio I1 / I2 is more preferably in the range of 3 to 5.9, and even more preferably 4 to 5.9. The analytical intensity of I2 is preferably 500 to 1,000, and more preferably 600 to 900. By adjusting the treatment time in an oxidizing atmosphere, it is possible to obtain r-CF(A) in which the intensity ratio I1 / I2 between the diffraction intensity I1 at a Bragg angle 2θ=25° and the diffraction intensity I2 at 2θ=44° observed by X-ray diffraction is less than 6.

[0022] From the viewpoint of further increasing the productivity of the thermoplastic resin composition of this embodiment, the bulk density of r-CF(A) is 0.03 to 1.0 g / cm 3 By using r-CF(A) having a bulk density in this range, it is possible to effectively prevent fibers from remaining at the supply port when supplying r-CF(A) to production equipment in the production of a thermoplastic resin composition, thereby improving productivity. A more preferred range for the bulk density of r-CF(A) is 0.05 to 1.0 g / cm. 3 and a more preferred range is 0.1 to 1.0 g / cm 3 By adjusting the rotation speed of the grinder rotary blade and the opening of the classification mesh, a bulk density of 0.05 to 1.0 g / cm3 can be achieved. 3 can be obtained.

[0023] The amount of r-CF(A) blended is preferably 10 to 40 mass%, more preferably 15 to 35 mass%, and even more preferably 20 to 30 mass%, based on 100 mass% of the thermoplastic resin composition, from the viewpoint of achieving a balance between mechanical properties, processability, and productivity.

[0024] <Thermoplastic resin (B)> A thermoplastic resin is a resin that softens and becomes plastic when heated to an appropriate temperature and solidifies when cooled, and the thermoplastic resin (B) according to this embodiment has an average solubility parameter of 9 to 15. The thermoplastic resin (B) can be used alone or in combination of two or more, and includes at least one of an acrylic resin (B1) having a glass transition temperature of 0°C or higher and a styrene resin (B2) having a glass transition temperature of 0°C or higher.

[0025] When two or more thermoplastic resins are used, it is not necessary for the solubility parameter of each thermoplastic resin to be in the range of 9 to 15; it is sufficient that the average solubility parameter of the thermoplastic resins used when blended is in the range of 9 to 15.

[0026] As used herein, the average solubility parameter refers to a value calculated by the Fedor method, and is determined by the method described in the Examples section below. By combining a thermoplastic resin (B) containing at least one of an acrylic resin (B1) and a styrene resin (B2) having an average solubility parameter of 9 to 15 and a glass transition temperature of 0°C or higher with r-CF (A) having an oxygen content of 5.0 mass% or higher, the compatibility between the r-CF (A) and the thermoplastic resin (B) can be significantly improved, resulting in improved adhesion. As a result, impact resistance can be improved. The solubility parameter of the thermoplastic resin (B) is more preferably in the range of 9 to 12.

[0027] From the viewpoint of more effectively increasing impact resistance, it is more preferable that the solubility parameter of each resin used in the thermoplastic resin (B) is 9 to 15.

[0028] The thermoplastic resin (B) may be used in combination with a resin other than the acrylic resin (B1) or the styrene resin (B2) having a solubility parameter of 9 to 15, provided that the effects of the present invention are not impaired. However, it is preferable that at least one of the acrylic resin (B1) and the styrene resin (B2) is the main component. If the average solubility parameter is within this range, other thermoplastic resins such as acrylic resins other than the acrylic resin (B1) and the styrene resin (B2), or styrene resins may be used in combination. The main component refers to the thermoplastic resin that is contained in the largest amount among the components that make up the thermoplastic resin (B).

[0029] Even when recycled carbon fibers (A) are used, from the viewpoint of being able to obtain a thermoplastic resin composition having excellent productivity and excellent impact resistance, the content of the acrylic resin (B1) or the styrene resin (B2) in 100% by mass of the thermoplastic resin (B) is preferably 52 to 95% by mass, more preferably 55 to 100% by mass, and even more preferably 60 to 90% by mass. When both the acrylic resin (B1) and the styrene resin (B2) are contained, the total content is the total content.

[0030] The acrylic resin (B1) and the styrene resin (B2) have a glass transition temperature of 0°C or higher, preferably 0°C or higher and 140°C or lower, and more preferably 25 to 130°C. This makes it possible to achieve high productivity and satisfactory mechanical properties. The glass transition temperature in the present invention is a value determined using a differential scanning calorimeter (DSC) in accordance with JIS K7121:2012.

[0031] The solubility parameter of the acrylic resin (B1) or styrene resin (B2) contained in the thermoplastic resin (B) is preferably 9 to 15, more preferably 9 to 12, from the viewpoints of high productivity and mechanical properties.

[0032] The average MFR of the thermoplastic resin (B) is preferably 10 g / min or more, more preferably 20 g / min or more. This reduces the melt viscosity when r-CF (A) and thermoplastic resin (B) are kneaded, and prevents the r-CF (A) from breaking, resulting in high mechanical properties. The upper limit of the average MFR of thermoplastic resin (B) is not particularly limited, but is usually 200 g / min or less from the viewpoint of availability.

[0033] [Acrylic resin (B1)] The acrylic resin (B1) is an acrylic resin having a glass transition temperature of 0°C or higher, and can be obtained by polymerizing a (meth)acrylic monomer. Examples of the monomer include (meth)acrylic monomers having an alkyl group, (meth)acrylic monomers having a hydroxyl group, (meth)acrylic monomers having a carboxyl group, (meth)acrylic monomers having a glycidyl group, and acrylic monomers having a vinyl ester group such as vinyl acetate or vinyl propionate. Among these, polymethyl methacrylate (PMMA) resin, which is a polymer of methyl methacrylate, is preferred because it can achieve a high elastic modulus.

[0034] Specific examples of the acrylic resin (B1) include ACRYPET TF-9 (manufactured by Mitsubishi Chemical Corporation, solubility parameter: 9.2, MFR 20 g / 10 min).

[0035] [Styrene-based resin (B2)] The styrene-based resin (B2) is an acrylic resin having a glass transition temperature of 0° C. or higher, and is a resin containing a styrene-based monomer as a monomer. In addition to homopolymers of styrene-based monomers, styrene-based resins obtained by copolymerizing other vinyl monomers copolymerizable with these, or rubbery polymers, etc., as necessary, can be mentioned. Examples of the styrene-based monomer include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, vinylxylene, ethylstyrene, dimethylstyrene, p-tert-butylstyrene, vinylnaphthalene, methoxystyrene, monobromostyrene, dibromostyrene, fluorostyrene, and tribromostyrene, and from the viewpoint of excellent moldability, styrene is particularly preferred.

[0036] Examples of other vinyl monomers copolymerizable with styrene-based monomers include vinyl cyanide compounds such as acrylonitrile and methacrylonitrile, aryl esters of acrylic acid such as phenyl acrylate and benzyl acrylate, alkyl esters of acrylic acid such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, cyclohexyl acrylate, and dodecyl acrylate, aryl esters of methacrylic acid such as phenyl methacrylate and benzyl methacrylate, and methyl methacrylate. Examples of methacrylic acid alkyl esters include methacrylic acid alkyl esters such as acrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, cyclohexyl methacrylate, and dodecyl methacrylate; epoxy group-containing methacrylic acid esters such as glycidyl methacrylate; maleimide-based monomers such as maleimide, N-methylmaleimide, and N-phenylmaleimide; and α,β-unsaturated carboxylic acids and anhydrides thereof such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, phthalic acid, and itaconic acid.

[0037] Examples of rubbery polymers copolymerizable with styrene monomers include diene copolymers such as polybutadiene, polyisoprene, random and block copolymers of styrene and butadiene, acrylonitrile and butadiene copolymers, copolymers of alkyl acrylates or alkyl methacrylates and butadiene, and butadiene and isoprene copolymers; copolymers of ethylene and α-olefins such as ethylene and propylene random and block copolymers and ethylene and butene random and block copolymers; copolymers of ethylene and unsaturated carboxylic acid esters such as ethylene and methyl methacrylate copolymers and ethylene and butyl acrylate copolymers; copolymers of ethylene and aliphatic vinyls such as ethylene and vinyl acetate copolymers; terpolymers of ethylene, propylene, and non-conjugated dienes such as ethylene, propylene, and hexadiene copolymers; acrylic rubbers such as polybutyl acrylate; and composite rubbers in which the polyorganosiloxane rubber component and the polyalkyl(meth)acrylate rubber component are intertwined so that they cannot be separated.

[0038] Examples of styrene-based resins composed of these monomers include polystyrene, styrene-butadiene-styrene copolymer (SBS), high impact polystyrene (HIPS), acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), methyl methacrylate-butadiene-styrene copolymer (MBS resin), methyl methacrylate-acrylonitrile-butadiene-styrene copolymer (MABS resin), acrylonitrile-acrylic rubber-styrene copolymer (AAS resin), acrylonitrile-ethylene propylene rubber-styrene copolymer (AES resin), and styrene-IPN type rubber copolymer, or mixtures of these.

[0039] Furthermore, rubbery polymers copolymerizable with styrene-based monomers include polymers made of polybutadiene or polyisoprene whose unsaturated bonds have been hydrogenated. Specific examples of such polymers include hydrogenated styrene-butadiene-styrene copolymer (hydrogenated SBS) and hydrogenated styrene-isoprene-styrene copolymer (hydrogenated SEPS). Among these, acrylonitrile-styrene copolymer (AS resin) or acrylonitrile-butadiene-styrene copolymer (ABS resin) is preferred due to its good compatibility with r-CF(A), and acrylonitrile-butadiene-styrene copolymer (ABS resin) is even more preferred due to its good impact resistance.

[0040] A specific example of the AS resin is Cevian 090SF (manufactured by Daicel Miraizu Co., Ltd., solubility parameter MFR 23 g / 10 min), etc. A specific example of the ABS resin is Cevian T-500SF (manufactured by Daicel Miraizu Co., Ltd., MFR 25 g / 10 min), etc.

[0041] [Acid-modified thermoplastic elastomer (b-1)] The thermoplastic resin (B) may contain an acid-modified thermoplastic elastomer (b-1). In this specification, the term "thermoplastic elastomer" refers to a polymer that softens and becomes plastic when heated to an appropriate temperature, exhibits elasticity when cooled, and does not exhibit a melting point as determined by the DSC method. By combining r-CF (A) with the thermoplastic resin (B) and further including the acid-modified thermoplastic elastomer (b-1) as the thermoplastic resin (B), compatibility is significantly improved, enabling the production of a thermoplastic resin composition with high impact resistance. An "acid-modified thermoplastic elastomer" refers to a thermoplastic elastomer into which an acidic functional group has been introduced by graft polymerization or the like. Suitable examples of acid-modified thermoplastic elastomers include acid-modified styrene-based elastomers and acid-modified olefin-based elastomers. Acid modification refers to the introduction of cyclic acid anhydride groups or carboxylic acid groups into the copolymer side chains using, for example, cyclic acid anhydrides such as succinic anhydride, maleic anhydride, glutaric anhydride, or phthalic anhydride.

[0042] The glass transition temperature of the acid-modified thermoplastic elastomer (b-1) is preferably lower than 0° C. The glass transition temperature in the present invention is a value determined using a differential scanning calorimeter (DSC) in accordance with JIS K7121:2012.

[0043] Examples of the styrene-based elastomer include block copolymers composed of polystyrene blocks and polyolefin elastomer blocks, such as styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-ethylene-butylene-styrene block copolymer (SEPS), styrene-butylene-styrene block copolymer (SBS), hydrogenated styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-butadiene-isoprene-styrene block copolymer (SBIS), and hydrogenated styrene-butadiene-isoprene-styrene block copolymer (SEEPS).

[0044] Examples of the olefin-based elastomer include ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylate copolymer, ethylene-propylene-diene terpolymer, isoprene rubber, nitrile rubber, and polybutene rubber.

[0045] Commercially available products include, for example, maleic anhydride-modified isoprene rubber such as LIR-403 (manufactured by Kuraray Co., Ltd.); modified isoprene rubber such as LIR-410 (manufactured by Kuraray Co., Ltd.); carboxy-modified nitrile rubber such as Krynac 110, 221, and 231 (manufactured by Polycer Corporation); maleic anhydride-modified polybutene such as Nisseki Polybutene (manufactured by Nippon Oil Corporation); ethylene methacrylic acid copolymer such as Nucrel (manufactured by DuPont-Mitsui Polychemicals Co., Ltd.); ethylene methacrylic acid copolymer such as Yukalon (manufactured by Mitsubishi Chemical Corporation); maleic anhydride-modified ethylene-propylene rubber such as Tafmer M (MA8510 (manufactured by Mitsui Chemicals Co., Ltd.)) and TX-1215 (manufactured by Mitsui Chemicals Co., Ltd.); maleic anhydride-modified ethylene-butene rubber such as Tafmer M (MH7020 (manufactured by Mitsui Chemicals Co., Ltd.)); and HPR series (maleic anhydride-modified EEA ( Examples of maleic anhydride-modified polyethylenes include maleic anhydride-modified polyethylenes (manufactured by DuPont-Mitsui Polychemicals), Bondine (maleic anhydride-modified EEA (manufactured by Atofina)), Tuftec (maleic anhydride-modified SEBS, M1943 (manufactured by Asahi Kasei Corporation)), Kraton (maleic anhydride-modified SEBS, FG1901X (manufactured by Kraton Polymers)), Tufprene (maleic anhydride-modified SBS, 912 (manufactured by Asahi Kasei Corporation)), Septon (maleic anhydride-modified SEPS (manufactured by Kuraray Co., Ltd.)), Rexpearl (maleic anhydride-modified EEA, ET-182G, 224M, 234M (manufactured by Japan Polyolefins Co., Ltd.)), and Aurouren (maleic anhydride-modified EEA, 200S, 250S (manufactured by Nippon Paper Chemicals Co., Ltd.)); and maleic anhydride-modified polypropylenes (manufactured by Admer, QB550, LF128 (manufactured by Mitsui Chemicals, Inc.)).

[0046] A particularly suitable example of the acid-modified thermoplastic elastomer (b-1) is a maleic anhydride-modified styrene-ethylene-butadiene-styrene copolymer. Commercially available acid-modified styrene-ethylene-butylene-styrene block copolymers include Tuftec M1911 (manufactured by Asahi Kasei Chemicals Corporation) with an acid value of 2 mg CHONa / g and a MFR of 4.5 g / 10 min, Tuftec M1913 (manufactured by Asahi Kasei Chemicals Corporation) with an acid value of 10 mg CHONa / g and a MFR of 5.0 g / 10 min, and Tuftec M1943 (manufactured by Asahi Kasei Chemicals Corporation) with an acid value of 10 mg CHONa / g and a MFR of 8.0 g / 10 min.

[0047] The acid-modified thermoplastic elastomer (b-1) increases the impact strength of the resulting r-CFRP. The Charpy impact strength measured in accordance with JIS K7111-1 is 20 kJ / m 2 It is preferable that the concentration is 30 kJ / m or more. 2 The upper limit of the Charpy impact strength of the acid-modified thermoplastic elastomer (b-1) is not particularly limited, and any elastomer that does not break can be suitably used.

[0048] The average MFR of the acid-modified thermoplastic elastomer (b-1) is preferably 1.0 g / 10 min or more, more preferably 5.0 g / 10 min or more. When the average MFR of the acid-modified thermoplastic elastomer (b-1) is within the above range, the melt viscosity during processing is reduced, fiber breakage of the r-CF (A) during processing can be suppressed, and high physical properties can be achieved.

[0049] The amount of the acid-modified thermoplastic elastomer (b-1) is preferably 5 to 20 mass%, more preferably 5 to 15 mass parts, and even more preferably 5 to 10 mass%, based on 100 mass% of the thermoplastic resin composition, from the viewpoint of further improving both the elastic modulus and the impact strength.

[0050] When the acid-modified thermoplastic elastomer (b-1) is used, since both the elastic modulus and impact strength can be achieved, the content of the acid-modified thermoplastic elastomer (b-1) in 100% by mass of the thermoplastic resin (B) is preferably 3 to 40% by mass, more preferably 5 to 35% by mass, and even more preferably 7 to 30% by mass.

[0051] The acid value of the acid-modified thermoplastic elastomer (b-1) is preferably 0.5 to 40 mg CH3ONa / g, more preferably 1 to 30 mg CH3ONa / g. When the acid value of the acid-modified thermoplastic elastomer (b-1) is in the range of 0.5 to 40 mg CH3ONa / g, the interfacial adhesion between the r-CF (A) and the thermoplastic resin (B) can be improved.

[0052] <Optional ingredients> The thermoplastic resin composition of this embodiment may contain an inorganic filler as an optional component. Examples of inorganic fillers include silica, heat-dissipating fillers, talc, calcium silicate, wollastonite, montmorillonite, and hydrotalcite. Furthermore, if necessary, other additives conventionally used to modify resins may be added, such as weathering stabilizers, light resistance stabilizers, antioxidants, antioxidants, softeners, dispersants, fillers, colorants, lubricants, heat stabilizers, antistatic agents, UV absorbers, and flame retardants such as halogen-based, phosphorus-based, or metal oxide flame retardants. Metal soaps of alkali metals, alkaline earth metals, or zinc, nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants may also be added.

[0053] <Method of producing thermoplastic resin composition> The thermoplastic resin composition can be obtained by kneading the ingredients at a temperature at which the thermoplastic resin (B) melts. For example, r-CF (A), thermoplastic resin (B), and, if necessary, various additives and colorants can be added and kneaded using a batch mixer such as a kneader, roll mill, super mixer, high-speed mixer, ball mill, sand mill, attritor, or Banbury mixer, a single-screw extruder, a twin-screw extruder, or a rotor-type twin-screw mixer to produce a resin composition in the form of pellets, powder, granules, or beads. The method of pelletizing using a twin-screw extruder is preferred because of its strong kneading power and ease of subsequent molding.

[0054] The thermoplastic resin composition can be used as a masterbatch by diluting it with a molding resin during molding. Alternatively, a required amount of r-CF (A) may be blended with a thermoplastic resin (B) to form a compound that can be molded directly without diluting it with a molding resin.

[0055] The amount of r-CF(A) in 100% by mass of the masterbatch is 41 to 70% by mass, and more preferably 50 to 65% by mass. By setting the amount of r-CF(A) in the above range, the productivity and mechanical properties of the masterbatch can be improved. In the masterbatch, the resin used for dilution during molding can be any of those exemplified as the thermoplastic resin (B) described above. Because of its excellent compatibility, it is preferable to use the same resin as the thermoplastic resin (B) used to disperse the r-CF(A). The thermoplastic resin composition of this embodiment has excellent dispersibility of r-CF(A), and therefore can be stably formed even when made into a high-concentration resin composition such as a masterbatch. It can be shaped.

[0056] When the thermoplastic resin composition of this embodiment is made into a compound, the amount of r-CF(A) in 100% by mass of the compound is preferably 10 to 40% by mass, more preferably 15 to 35% by mass. By setting the amount of r-CF(A) in the above range, both productivity and moldability of the compound can be achieved.

[0057] <<Molded body>> The molded article according to this embodiment is obtained by molding the thermoplastic resin composition according to this embodiment. The molding method is not particularly limited, and the molded article can be produced by, for example, extrusion molding, injection molding, blow molding, etc. The thermoplastic resin composition according to this embodiment has excellent strength and moldability, and is therefore suitable for molding injection-molded articles such as automobile parts having complex shapes. [Example]

[0058] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. Items without numerical values ​​in the tables indicate that the element is not contained.

[0059] 《Measurement method》 The physical properties of each raw material, Examples, Reference Examples and Comparative Examples (hereinafter referred to as Examples, etc.) were measured by the following methods. 1) Measurement of oxygen content in recycled carbon fiber The oxygen content of r-CF(A) was measured at an acceleration voltage of 15 kV and a field magnification of 3000 times using an energy dispersive X-ray spectrometer attached to a scanning electron microscope (SEM). 2) Measurement of the average solubility parameter of the thermoplastic resin (B), etc. The solubility parameter of the thermoplastic resin was calculated by Fedor's method. Specifically, it was calculated by the following formula (1) in accordance with the description in Polym. Eng. Sci., vol. 14, p. 147 (1974). Formula (1): SP value = √(Ev / v) = √(ΣΔei / ΣΔvi) (In the formula, Ev: evaporation energy (cal / mol), v: molar volume (cm 3 / mol), Δei: evaporation energy of each atom or atomic group, Δvi: molar volume of each atom or atomic group) 3) Measurement of the diffraction intensity I1 (2θ = 25°) and diffraction intensity I2 (2θ = 44°) of r-CF(A), etc. Using XRD (X-ray Diometer) with Cu-Kα as the radiation source, the diffraction intensity of pulverized and powdered r-CF in the range of 5° < 2θ < 110° was measured. 4) Measurement of the bulk density of r-CF(A), etc. The bulk density of r-CF(A), etc. was measured in accordance with JIS K5101. 5) Measurement of the average MFR of the thermoplastic resin (B), etc. The MFR of the thermoplastic resin (B), etc. was measured in accordance with JIS K7210-1. 6) Measurement of the Charpy impact strength of the thermoplastic resin (B), etc. and the molded body The Charpy impact strength of the acid-modified thermoplastic elastomer (b-1) and the molded body was measured in accordance with JIS K7111-1. 7) Measurement of the glass transition temperature of the thermoplastic resin (B), etc. In accordance with JIS K7121:2012, the glass transition temperature of the thermoplastic resin (B), etc. was measured using a differential scanning calorimeter (DSC).

[0060] <Production of r-CF> 《Production Example 1》 The CFRP derived from aircraft end materials was heat-treated at 750 °C in a steam atmosphere for 4 hours hours hours. Subsequently, it was heat-treated at 550 °C for 6 hours in air to obtain a regenerated carbon fiber mass. After crushing the obtained regenerated carbon fiber mass with a cutting machine, fibers of 4 - 15 mm were recovered, thereby obtaining the regenerated carbon fiber r-CF-A according to Production Example 1.

[0061] 《Production Example 2》 The regenerated carbon fiber r-CF-B according to Production Example 2 was obtained by the same method as in Production Example 1, except that the CFRP derived from aircraft end materials was changed to CFRP derived from automotive part waste materials.

[0062] 《Production Example 3》 The regenerated carbon fiber r-CF-C according to Production Example 3 was obtained by the same materials and production method as in Production Example 1, except that the step of crushing with a cutting machine was not performed and a step of pulverizing with a pulverizer was performed.

[0063] 《Raw Materials》 The raw materials used in the examples, etc. are shown below. <r-CF(A) etc.> · A-I: r-CF-A (oxygen content 6 mass%, I1 / I2 = 5.8, bulk density 0.25 g / cm 3 ) · A-II: r-CF-B (oxygen content 6 mass%, I1 / I2 = 5.0, bulk density 0.10 g / cm 3 ) · A-III: r-CF-C (oxygen content 6 mass%, I1 / I2 = 5.9, bulk density 0.0 3 g / cm 3 ) · A’-IV: v-CF-A (manufactured by Mitsubishi Chemical Corporation, oxygen content 0 mass%, I1 / I2 = 6 .9, bulk density 0.53 g / cm 3 ) <Thermoplastic Resin (B) etc.> · B1-I: Acrypet TF-9 (PMMA resin, manufactured by Mitsubishi Chemical Corporation, solubility parameter: 9.2, glass transition temperature: 90 °C, MFR 20 g / 10 min) B1-II: ACRYPET VH-3F (PMMA resin, manufactured by Mitsubishi Chemical Corporation, solubility parameter: 9.5, glass transition temperature: 90°C, MFR 1.8g / 10min) B2a-I: Cevian T-500SF (ABS resin, manufactured by Daicel Miraize Co., Ltd., solubility parameter: 9.6, glass transition temperature: 80°C, MFR: 25g / 10min) B2a-II: Cevian 466MD (ABS resin, manufactured by Daicel Miraize Co., Ltd., solubility parameter: 9.9, glass transition temperature: 95°C, MFR: 4.0g / 10min) B2b-I: Cevian 090SF (AS resin, manufactured by Daicel Miraize Co., Ltd., solubility parameter: 10.0, glass transition temperature: 100°C, MFR: 23g / 10min) B2b-II: Sunrex SAN-H (AS resin, manufactured by Techno UMG, solubility parameter: 10.7, glass transition temperature: 105°C, MFR 5.0g / 10min) B'-III: PP, PMA60Z (PP resin, manufactured by SunAllomer, solubility parameter 9.3, glass transition temperature: 0°C, MFR 45g / 10min) [Acid-modified thermoplastic elastomer (b-1), etc.] b-1-I: Acid-modified SEBS, Tuftec M1943 (manufactured by Asahi Kasei Chemicals Corporation, acid value 10 mg CH3ONa / g, glass transition temperature: -40°C, MFR 8.0 g / 10 min) b'-1-II: SEBS, Tuftec H1221 (Asahi Kasei Chemicals Corporation, MFR 5g / 10min, glass transition temperature: -42°C, not acid-modified)

[0064] <Production of Thermoplastic Resin Composition> Example 1 20 parts by mass of A-1 as r-CF (A) and 80 parts by mass of thermoplastic resin (B1-1) (ACRYPET TF-9 (PMMA resin, manufactured by Mitsubishi Chemical Corporation, solubility parameter: 9.2, glass transition temperature: 90°C, MFR 20 g / 10 min)) as thermoplastic resin (B) were extruded at 250°C in a twin-screw extruder (manufactured by The Japan Steel Works, Ltd.) and granulated to obtain a thermoplastic resin composition (D-1) (see Table 1).

[0065] (Examples 2 to 36, Reference Examples 1 to 3, Comparative Example 1) Thermoplastic resin compositions were obtained in the same manner as in Example 1, except that the materials and blending amounts (parts by mass) were changed to those shown in Tables 1 to 3. Tables 4 to 6 show the physical properties of the r-CF (A) and thermoplastic resin (B) in each example.

[0066] [Table 1]

[0067] [Table 2]

[0068] [Table 3]

[0069] [Table 4]

[0070] [Table 5]

[0071] [Table 6]

[0072] <Evaluation of Thermoplastic Resin Composition> The thermoplastic resin compositions according to the respective Examples were evaluated as follows. The results are shown in Table 3. α) Evaluation of productivity (deposits on the die tip) When 2 kg of the thermoplastic resin composition of each example was produced at a discharge rate of 20 kg / h, The amount of deposits generated on the end dies was evaluated according to the following criteria. +++: The weight of the deposit is less than 1g. Productivity is particularly good. ++: The weight of the deposit is between 1g and 3g. Productivity is good. +: The weight of the deposit is between 3g and 5g. Productivity is possible. NG: Weight of deposit is 5g or more. Productivity is poor. β) Evaluation of productivity (fiber retention) Similarly, regarding the fiber supplyability during extrusion processing of the thermoplastic resin compositions of each Example, the degree of fiber retention at the raw material supply port when the fibers were supplied at a discharge rate of 6 kg / h using a gravimetric feeder with a hopper capacity of 25 L was visually evaluated. +++: No retention occurs. Productivity is particularly good. ++: Slight retention occurs. Productivity is good. +: Retention occurs to a degree that does not affect extrusion processing. Productivity is possible. NG: Fiber is not supplied to the extruder due to retention. Productivity is poor.

[0073] <Production of Molded Product> The thermoplastic resin compositions of the respective Examples were molded using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) to obtain multipurpose test pieces measuring 80 mm in length, 10 mm in width, and 4 mm in thickness.

[0074] <Evaluation of molded products> The molded articles according to the respective Examples were evaluated as follows. The results are shown in Table 3. γ) Evaluation of elastic modulus The obtained multipurpose test pieces of each example were used to measure the flexural modulus in accordance with JIS K7171:2016. The higher the measured value, the better the strength. The evaluation criteria for the modulus were as follows: +++: 10,000 MPa or more. Excellent. ++: 8000 MPa or more and less than 10000 MPa. Good. +: 5000 MPa or more, but less than 8000 MPa. Practical range. NG: Less than 5000MPa. Poor. δ) Evaluation of Charpy impact strength The notched Charpy impact strength was measured according to JIS K7111-1:2012 using the obtained multipurpose test specimens of each Example, etc. Evaluation criteria were as follows. +++:15kJ / m 2 That's it. Excellent. ++7kJ / m 2 More than 15kJ / m 2 Less than. Good. +:5kJ / m 2 More than 7kJ / m 2 Less than. Practical range. NG: 5kJ / m 2 less than. For applications requiring high strength such as automotive parts, a Charpy impact strength of 7kJ / m 2 It is preferable that this is equal to or greater than this.

[0075] [Table 7]

[0076] [Table 8]

[0077] [Table 9]

[0078] Molded articles formed from thermoplastic resin compositions combining r-CF (A) having an oxygen content of 5.0 mass% or more and thermoplastic resin (B) having a solubility parameter of 9 to 15 are excellent in productivity, elastic modulus, and impact strength, as shown in the examples in Table 3. It was confirmed that the molded article of Reference Example 1, which was formed from a thermoplastic resin composition in which the plastic resin (B) was combined, exhibited excellent effects equivalent to those of the molded article of Reference Example 1.

Claims

1. A thermoplastic resin composition for carbon fiber reinforcement containing recycled carbon fibers (A) and a thermoplastic resin (B), The oxygen content in the recycled carbon fiber (A) is 5.0% by mass or more, the thermoplastic resin (B) has an average solubility parameter of 9 to 15 and contains at least one of an acrylic resin (B1) and a styrene resin (B2); The acrylic resin (B1) and the styrene resin (B2) have a glass transition temperature of 0°C or higher, The amount of recycled carbon fiber (A) is 10 to 40% by mass based on 100% by mass of the thermoplastic resin composition. Thermoplastic resin composition. (Note that the oxygen content is a value measured using an energy dispersive X-ray spectrometer attached to a scanning electron microscope (SEM) at an acceleration voltage of 15 kV and a visual field magnification of 3000 times.) The average solubility parameter is a value calculated by the following formula (1). Equation (1): SP value = √(Ev / v) = √(ΣΔei / ΣΔvi) (Wherein, Ev: evaporation energy (cal / mol), v: molar volume (cm ３ / mol), Δei: evaporation energy of each atom or atomic group, Δvi: molar volume of each atom or atomic group.

2. Diffraction intensity I at Bragg angle 2θ = 25° observed by X-ray diffraction of recycled carbon fiber (A) １ and the diffraction intensity I at 2θ=44° ２ Intensity ratio I １ / I ２ is less than 6 The thermoplastic resin composition according to claim 1, characterized by:

3. The bulk density of the recycled carbon fiber (A) is 0.03 to 1.0 g / cm ３ 3. The thermoplastic resin composition according to claim 1, wherein (However, the bulk density is a value obtained in accordance with JIS K5101.)

4. The thermoplastic resin composition according to any one of claims 1 to 3, wherein the thermoplastic resin (B) contains an acid-modified thermoplastic elastomer (b-1).

5. A molded article obtained by molding the thermoplastic resin composition according to any one of claims 1 to 4.

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