Fiber-reinforced thermoplastic resin molded product

Abstract

This fiber-reinforced thermoplastic resin molded article contains a thermoplastic resin [A] and carbon fibers [B], wherein: with respect to a total of 100 parts by weight of the thermoplastic resin [A] and the carbon fibers [B], the content of the thermoplastic resin [A] is 50 to 95 parts by weight and the content of the carbon fibers [B] is 5 to 50 parts by weight; the bending modulus of the molded article is 30 GPA or greater; the interfacial shear strength between the thermoplastic resin [A] and the carbon fibers [B] is 15 MPa or greater; and the logarithmic decrement of the molded article calculated by formula (1) is less than 3. Provided is a thermoplastic resin molded article having excellent acoustic properties as a result of having excellent vibration persistence. Formula (1): Logarithmic decrement δ = (1 / n) × ln(α(1) / α(1+n))

Description

Technical Field

[0001] The present invention relates to a fiber-reinforced thermoplastic resin molded article containing a thermoplastic resin and carbon fibers, and capable of exhibiting excellent vibration sustainability.

Background Art

[0002] Molded articles containing reinforcing fibers and thermoplastic resins are widely used in applications such as electrical and electronic parts, automotive applications, sports goods applications, aerospace applications, and general industrial applications because they are lightweight and have excellent mechanical properties. The reinforcing fibers used in these molded articles reinforce the molded articles in various forms depending on the application. These reinforcing fibers include metal fibers such as aluminum fibers and stainless steel fibers; organic fibers such as aramid fibers and PBO (polyparaphenylene benzoxazole) fibers; inorganic fibers such as silicon carbide fibers, and carbon fibers. Carbon fibers are suitable from the viewpoint of the balance of specific strength, specific rigidity, and light weight, and among them, polyacrylonitrile (PAN)-based carbon fibers are particularly preferably used.

[0003] Since carbon fibers have excellent specific strength and specific rigidity, molded articles reinforced with carbon fibers have excellent mechanical properties, and thus various studies have been conducted as alternative materials for metal materials.

[0004] As a technique for enhancing the mechanical properties of fiber-reinforced thermoplastic resin molded articles, molded articles obtained by blending carbon fibers and polyarylene sulfide resins (see, for example, Patent Documents 1 and 2), and fiber-reinforced resin compositions in which the carbon fiber content is increased for the purpose of increasing the elastic modulus of the molded article (for example, Patent Document 3) have been proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] However, since a carbon fiber reinforced resin molded article has higher vibration damping properties than a metal material, for example, when used in an acoustic device or the like, energy of sound and vibration may be lost inside the material. As a result, the acoustic properties obtained by using the molded article have problems such as insufficient sound pressure, reduction of reverberant sound, and insufficient sound quality in bass and treble, and are not satisfactory acoustic properties as an alternative to metal materials.

[0007] The techniques disclosed in Patent Documents 1 to 3 are intended to improve mechanical properties, and the molded articles obtained by these techniques have insufficient vibration persistence and acoustic properties.

[0008] In view of the problems of the prior art, an object of the present invention is to provide a fiber-reinforced thermoplastic resin molded article having excellent vibration persistence and acoustic properties. [Means for Solving the Problems]

[0009] In order to solve the above problems, the present invention has the following configuration.

[0010] A fiber-reinforced thermoplastic resin molded article containing a thermoplastic resin [A] and carbon fibers [B], wherein, based on a total of 100 parts by weight of the thermoplastic resin [A] and the carbon fibers [B], the thermoplastic resin [A] is 50 to 95 parts by weight and the carbon fibers [B] is 5 to 50 parts by weight, the flexural modulus of the molded article is 30 GPa or more, the interfacial shear strength between the thermoplastic resin [A] and the carbon fibers [B] is 15 MPa or more, and the logarithmic decrement of the molded article represented by the following formula (1) is less than 3. Logarithmic decrement δ = (1 / n) × ln(α (1) / α (1+n)) Equation (1) Here δ: Logarithmic decrement n: Period (n = 100) α (1) : Maximum amplitude value α (1+n) : Amplitude value of the n-th period counted from the period having the maximum amplitude value

Advantages of the Invention

[0011] The fiber-reinforced thermoplastic resin molded article of the present invention is excellent in the vibration persistence of the molded article, and the acoustic characteristics of the molded article are remarkably improved. The fiber-reinforced thermoplastic resin molded article of the present invention is extremely useful for various parts and members such as acoustic devices, electric and electronic devices, OA devices, household electric appliances, automobile parts, interior members, sports parts, and housings.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0013] In the fiber-reinforced thermoplastic resin molded article of the present invention (hereinafter, may be referred to as "molded article"), the blending amount of carbon fiber [B] is 5 parts by weight or more and 50 parts by weight or less with respect to a total of 100 parts by weight of thermoplastic resin [A] and carbon fiber [B]. When the content of carbon fiber [B] is less than 5 parts by weight, the mechanical properties of the molded article, particularly the elastic modulus, decrease. The content of carbon fiber [B] is preferably 20 parts by weight or more, more preferably 30 parts by weight or more, and still more preferably 40 parts by weight or more. Also, when the content of carbon fiber [B] exceeds 50 parts by weight, the dispersibility of carbon fiber [B] in the molded article decreases, often causing a decrease in the mechanical properties of the molded article, particularly the elastic modulus. The content of carbon fiber [B] is preferably 45 parts by weight or less. The blending amount of thermoplastic resin [A] is 50 parts by weight or more and 95 parts by weight or less with respect to a total of 100 parts by weight of thermoplastic resin [A] and carbon fiber [B]. The content of thermoplastic resin [A] is preferably 55 parts by weight or more. Also, the blending amount of thermoplastic resin [A] is preferably 80 parts by weight or less, more preferably 70 parts by weight or less, and still more preferably 60 parts by weight or less.

[0014] The flexural elastic modulus of the molded article of the present invention is 30 GPa or more. When sound or vibration is applied to the molded article, vibration is generated in the molded article by the applied energy. However, when the elastic modulus of the molded article is 30 GPa or more, the molded article is less likely to deform, so the energy loss associated with deformation is small. Therefore, it is considered that the vibration persistence of the molded article is improved. When the flexural elastic modulus of the molded article is less than 30 GPa, the energy loss due to deformation increases, and the vibration persistence is poor. The elastic modulus is preferably 35 GPa or more, more preferably 40 GPa or more, and still more preferably 45 GPa or more. On the other hand, from the viewpoint of the processability of the molded article, the flexural elastic modulus of the molded article is preferably 70 GPa or less. The flexural elastic modulus of the molded article is preferably 65 GPa or less, more preferably 60 GPa or less. In order to make the flexural elastic modulus of the molded article within such a range, it is preferable to adjust the blending amount of carbon fiber [B] in the molded article to the above range. Also, it is preferable to make the tensile elastic modulus of the carbon fiber [B] used 200 GPa or more.

[0015] The flexural modulus of the molded product can be determined by molding an ISO dumbbell test piece from a molding material having the same composition as the molded product to be measured using an injection molding machine, and measuring the test piece in accordance with ISO 178:2010, Amd.1:2013, using a three-point bending test jig (with a roller radius of 5 mm) with a support distance set to 64 mm under test conditions of a test speed of 2 mm / min. As the testing machine to be used here, a commercially available general product may be used. For example, the "Instron" (registered trademark) universal testing machine model 5566 (manufactured by Instron Corporation) may be used as the testing machine.

[0016] In addition, in the molded product of the present invention, the interfacial shear strength between the thermoplastic resin [A] and the carbon fiber [B] is 15 MPa or more. The interfacial shear strength is preferably 17 MPa or more, more preferably 20 MPa or more. On the other hand, the interfacial shear strength is preferably 50 MPa or less. When the interfacial shear strength exceeds 50 MPa, fiber breakage is likely to occur during injection molding, and thus the mechanical properties of the molded product tend to deteriorate.

[0017] The energy of the sound and vibration applied to the molded product propagates through the inside of the molded product, and energy loss occurs, for example, in the gap between the thermoplastic resin [A] and the carbon fiber [B] where the elastic modulus is low, thereby attenuating. At this time, when the carbon fiber [B] having a high elastic modulus is included and the thermoplastic resin [A] and the carbon fiber [B] are firmly adhered, the applied energy can propagate via the carbon fiber [B] having a high elastic modulus, so there is no energy loss and it can be efficiently propagated inside the thermoplastic resin molded product. Therefore, it is considered that the vibration persistence of the molded product can be improved and the acoustic properties of the molded product can be improved. When the interfacial shear strength is less than 15 MPa, the energy applied to the molded product is lost in the gap between the thermoplastic resin molded product [A] and the carbon fiber [B], and it is not preferable because of poor vibration persistence.

[0018] Here, the measurement of the interfacial shear strength between the thermoplastic resin [A] and the carbon fiber [B] can be carried out by the following method. Using the same thermoplastic resin [A] and the same carbon fiber [B] that make up the molded product, the interfacial shear strength between the two is determined modelly. From above the thermoplastic resin [A] heated on the heater, the carbon fiber single filaments of the carbon fiber [B] are lowered, and one end of the carbon fiber is embedded in the resin so that the fiber becomes straight. At this time, the fiber embedding depth in the linear direction is designated as H. The embedding depth is preferably 100 to 3000 μm. The heating temperature is the same as the molding temperature when obtaining the molded product. After cooling the resin in which the carbon fiber single filaments are embedded to room temperature, the end of the carbon fiber single filament that is not embedded in the resin is fixed to a tensile testing machine, and the carbon fiber single filament is pulled out at a speed of 0.1 to 100 μm / second in the linear direction of the fiber and in the direction in which the fiber can be pulled out, and the maximum load F at that time is obtained.

[0019] Based on the following formula (2), the interfacial shear strength τ (MPa) can be obtained by dividing the maximum load F (N) by the product of the embedding depth H (μm) and the fiber circumference (π·df (μm)).

[0020] τ = F / (π·df·H)×10 -6 ···Formula (2) Here, π represents the circumference ratio, and df represents the fiber diameter. The fiber diameter df can be calculated using the average of the fiber diameters at three or more randomly selected points by observing the fiber before the pull-out measurement with an optical microscope (200 to 1000 times magnification). As a method for setting the interfacial shear strength within the above range, for example, adjusting the amount and type of the surface treatment agent adhering to the surface of the carbon fiber [B], or adding a compound having high affinity with the carbon fiber [B] to the thermoplastic resin [A] can be mentioned. As the surface treatment agent (so-called sizing agent) of the carbon fiber [B], those described later can be used.

[0021] Furthermore, the molded article of the present invention has a logarithmic decrement represented by the following formula (1) of less than 3. The logarithmic decrement is a numerical value obtained by taking the natural logarithm of the amplitude ratio over n periods in the free decay vibration waveform obtained when sound energy is applied to the inside of the molded article. In the present invention, using the following formula (1) for obtaining the logarithmic decrement, the logarithmic decrement of the amplitude value at the 100th period counted from the period having the maximum amplitude value with respect to the maximum amplitude value is obtained, and this numerical value is defined as the logarithmic decrement in the present invention.

[0022] The logarithmic decrement of the molded article is obtained by molding a test piece of 12.7 mm × 170 mm × 1 mmt using an injection molding machine from a molding material having the same composition as the molded article to be measured, and subjecting the test piece to a test by the one-end fixed impact method in accordance with JIS G0602:1993 "Test Method for Vibration Damping Characteristics of Vibration Damping Steel Sheets" to obtain a free vibration waveform with the horizontal axis being time and the vertical axis being displacement. Then, the logarithmic decrement can be calculated from the obtained free vibration waveform using the following formula (1), and the logarithmic decrement can be calculated with the period n being the 100th period. As the testing machine to be used here, a commercially available general product may be used. Logarithmic decrement δ = (1 / n) × ln(α (1) / α (1+n) ) Formula (1) δ: Logarithmic decrement n: Period (n = 100) α (1) : Maximum amplitude value α (1+n) : Amplitude value of the nth period counted from the period having the maximum amplitude value.

[0023] By making the logarithmic decrement less than 3, the vibration damping property of the molded product can be suppressed, creating a situation where the energy applied to the molded product is less likely to be lost, thus improving the acoustic properties. For example, when sound is applied to the molded product, the energy loss of the sound and vibration inside the molded product is small, and the sound coming out of the molded product can reverberate longer, enabling the expression of sound closer to that of a metal material. When the logarithmic decrement is greater than 3, the vibration damping property of the molded product becomes high, the energy loss of the sound and vibration inside the molded product becomes high, and the acoustic properties are inferior. The logarithmic decrement is preferably less than 2.5, more preferably less than 2. On the other hand, when the logarithmic decrement is 0, theoretically the molded product will continue to vibrate, that is, the sound inside the molded product will not decay, which is not preferable. The logarithmic decrement is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.5 or more.

[0024] In order to control the logarithmic decrement within the above range, it is important to keep the flexural modulus of the molded product and the interfacial shear strength between the thermoplastic resin [A] and the carbon fiber [B] within the above range. By increasing the flexural modulus of the molded product and the interfacial shear strength between the thermoplastic resin [A] and the carbon fiber [B], the loss of the energy of the sound and vibration applied to the molded product can be reduced, and the logarithmic decrement can be reduced.

[0025] Also, in the molded product of the present invention, the weight average fiber length [L w of the carbon fiber [B] present inside the molded product is preferably greater than 0.5 and 10 mm or less. As described above, when the thermoplastic resin [A] and the carbon fiber [B] have sufficient interfacial shear strength when energy of sound and vibration is applied to the molded product, the energy passing through the inside of the molded product propagates via the carbon fiber [B]. At this time, the longer the carbon fiber [B] remaining inside the molded product, the longer the distance that the energy can pass through the carbon fiber [B], so the energy loss can be suppressed. Therefore, the energy applied to the molded product can pass through a location with less loss, so the logarithmic decrement can be reduced, and it is considered that the vibration persistence of the molded product is improved.

[0026] In the molded article of the present invention, when the weight average fiber length [L w of the carbon fiber [B] is less than 0.5 mm, the energy propagation distance of the carbon fiber [B] in the molded article becomes small, so the vibration persistence decreases. In addition, since the effect of improving the mechanical properties by including the carbon fiber [B] becomes small, the acoustic properties deteriorate. L w When it is larger than 0.5 mm, a decrease in the vibration persistence of the molded article can be suppressed. L w is preferably 0.6 mm or more, more preferably 0.8 mm or more, and even more preferably 1.0 mm or more. The L of the carbon fiber [B] w By setting it to 10 mm or less, the effect of suppressing the entanglement between single filaments of the carbon fibers [B] is improved, and a decrease in dispersibility is suppressed, so a decrease in the vibration persistence of the molded article can be suppressed. L w is preferably 7 mm or less, more preferably 5 mm or less, and even more preferably 2 mm or less. L w When it exceeds 10 mm, the pattern of the carbon fibers on the surface of the molded article is likely to appear prominently, which may cause poor appearance.

[0027] Here, the "weight average fiber length" of the carbon fiber [B] in the present invention refers to the average fiber length calculated from the following formula considering the contribution of the fiber length by applying the calculation method of the weight average molecular weight to the calculation of the fiber length, rather than simply taking the number average. However, the following formula is applicable when the fiber diameter and density of the carbon fiber [B] are constant. Weight average fiber length = Σ(Mi 2 ×Ni) / Σ(Mi×Ni) Mi: Fiber length (mm) Ni: Number of carbon fibers with fiber length Mi.

[0028] The measurement of the above weight average fiber length can be performed by the following method. The molded article is heated while being sandwiched between glass plates on a hot stage set at 200 to 350 °C, and the carbon fiber [B] is uniformly dispersed by forming it into a film in the molded article. The film in which the carbon fiber [B] is uniformly dispersed is observed using an optical microscope (50 to 200 times). The fiber lengths of 1000 randomly selected carbon fibers [B] are measured, and the weight average fiber length [L is calculated from the above formula.w] Calculate it.

[0029] Note that the weight average fiber length [L w of the carbon fiber [B] in the molded product can be adjusted, for example, according to molding conditions and the like. Examples of molding conditions include, for injection molding, pressure conditions such as back pressure, time conditions such as injection time, and temperature conditions such as cylinder temperature and mold temperature. By increasing pressure conditions such as back pressure, the shearing force in the cylinder increases, causing the fibers to break and become shorter. Also, by shortening the injection time, the shearing force during injection increases, resulting in shorter fiber length. Furthermore, regarding temperature conditions, by lowering the temperature, the resin viscosity increases and the shearing force becomes higher, leading to shorter fiber length. By appropriately changing the conditions as described above, the weight average fiber length [L w of the carbon fiber [B] in the molded product can be set within a desired range.

[0030] Next, the constituent components of the molded product of the present invention will be described in detail.

[0031] The thermoplastic resin [A] preferably has a molding temperature (melting temperature) of 200 to 450°C. Specifically, polyolefin resins, polystyrene resins, polyamide resins, vinyl halide resins, polyacetal resins, saturated polyester resins, polycarbonate resins, polyarylsulfone resins, polyarylketone resins, polyarylene ether resins, polyarylene sulfide resins, polyaryl ether ketone resins, polyether sulfone resins, polyarylene sulfide sulfone resins, polyarylate resins, liquid crystal polyesters, fluorine resins, etc. can be mentioned. All of these correspond to electrical insulators. Two or more of these can also be used. These resins may have their end groups blocked or modified.

[0032] Among the above-mentioned thermoplastic resins, when used for applications such as electric and electronic devices and automotive parts, at least one resin selected from the group consisting of polycarbonate resin, polyolefin resin, polyamide resin, and polyarylene sulfide resin, which is lightweight and has an excellent balance of mechanical properties and moldability, is more preferable.

[0033] As the polyolefin resin, polypropylene resin is preferable. The polypropylene resin may be unmodified or modified.

[0034] Specific examples of the unmodified polypropylene resin include a homopolymer of propylene, and a copolymer of propylene and at least one α-olefin, conjugated diene, non-conjugated diene, or other thermoplastic monomer. Examples of the α-olefin include α-olefins having 2 to 12 carbon atoms excluding propylene, such as ethylene, 1-butene, 3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 1-nonene, 1-octene, 1-heptene, 1-hexene, 1-decene, 1-undecene, and 1-dodecene. Examples of the conjugated diene and non-conjugated diene include butadiene, ethylidene norbornene, dicyclopentadiene, 1,5-hexadiene, etc. Two or more of these may be used. The homopolymer of propylene is preferable from the viewpoint of improving the rigidity of the molded product, and the random or block copolymer of propylene and at least one α-olefin, conjugated diene, non-conjugated diene, etc. is preferable from the viewpoint of further improving the mechanical properties of the molded product.

[0035] Further, as the modified polypropylene resin, an acid-modified polypropylene resin is preferable, and an acid-modified polypropylene resin having a carboxylic acid and / or a salt group bonded to the polymer chain is more preferable. The above acid-modified polypropylene resin can be obtained by various methods. For example, it can be obtained by graft-polymerizing a monomer having a carboxylic acid group or a salt or esterified product thereof to an unmodified polypropylene resin.

[0036] Here, examples of the monomer having a carboxylic acid group include ethylenically unsaturated carboxylic acids, their anhydrides, and esterified products thereof. Further, compounds having an unsaturated vinyl group other than olefin are also included.

[0037] Examples of the ethylenically unsaturated carboxylic acid include (meth)acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, etc. Examples of the anhydride thereof include nadic acid TM (endo-cis-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid), maleic anhydride, citraconic anhydride, etc.

[0038] Two or more of these can also be used. Among these, acid anhydrides of ethylenically unsaturated carboxylic acids are preferable, and maleic anhydride is more preferable.

[0039] Here, in order to improve the mechanical properties of the molded article, it is preferable to use both the unmodified polypropylene resin and the modified polypropylene resin. Particularly from the viewpoint of the balance between flame retardancy and mechanical properties, it is preferable to use them such that the weight ratio of the unmodified polypropylene resin to the modified polypropylene resin is 95 / 5 to 75 / 25. More preferably, it is 95 / 5 to 80 / 20, and even more preferably, it is 90 / 10 to 80 / 20.

[0040] In the present invention, the polyamide resin is a resin mainly made from amino acids, lactams, or diamines and dicarboxylic acids. As its main raw materials, for example, amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, para-aminomethylbenzoic acid; lactams such as ε-caprolactam, ω-laurolactam; aliphatic diamines such as tetramethylenediamine, hexamethylenediamine, 2-methylpentamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine; aromatic diamines such as metaxylylenediamine, paraxylylenediamine; alicyclic diamines such as 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane; aliphatic dicarboxylic acids such as adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, etc. Two or more of these may be used.

[0041] From the viewpoint of excellent heat resistance and strength, polyamide resins having a melting point of 200 °C or higher are particularly useful. Specific examples thereof include polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polycaproamide / polyhexamethylene adipamide copolymer (nylon 6 / 66), polytetramethylene adipamide (nylon 46), polyhexamethylene sebacamide (nylon 610), polyhexamethylene dodecamide (nylon 612), polyhexamethylene terephthalamide / polycaproamide copolymer (nylon 6T / 6), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (nylon 66 / 6T), polylaurylamide / polyhexamethylene terephthalamide copolymer (nylon 12 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6I), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T / 6I), polyhexamethylene adipamide / polyhexamethylene isophthalamide / polycaproamide copolymer (nylon 66 / 6I / 6), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 6T / 6I), polyhexamethylene terephthalamide / polydodecaneamide copolymer (nylon 6T / 12), polyhexamethylene terephthalamide / poly(2-methylpentamethylene) terephthalamide copolymer (nylon 6T / M5T), polymetaxylylene adipamide (nylon MXD6), polynonamethylene terephthalamide (nylon 9T), and copolymers thereof. Two or more of these may be used.

[0042] Although there is no particular limitation on the degree of polymerization of the polyamide resin, since it has excellent fluidity during molding and a thin-walled molded product can be easily obtained, the sulfuric acid relative viscosity η measured at 25 °C of a solution obtained by dissolving 0.25 g of the polyamide resin in 25 ml of 98% concentrated sulfuric acid r is preferably in the range of 1.5 to 5.0, more preferably in the range of 2.0 to 3.5. Here, the sulfuric acid relative viscosity η rIt is represented by the viscosity ratio (flow-down second ratio) of the sample solution to 98% sulfuric acid from the flow-down rate measured using an Ostwald viscometer in a constant temperature bath at 25°C for a 98% sulfuric acid solution with a resin concentration of 1 g / 100 ml.

[0043] In the present invention, the polycarbonate resin is obtained by reacting a dihydric phenol with a carbonate precursor. It may also be a copolymer obtained using two or more dihydric phenols or two or more carbonate precursors. As an example of the reaction method, an interfacial polymerization method, a melt transesterification method, a solid-phase transesterification method of a carbonate prepolymer, and a ring-opening polymerization method of a cyclic carbonate compound can be mentioned.

[0044] Examples of the dihydric phenol include 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, bis(4-hydroxyphenyl)alkane (such as bisphenol A), 2,2-bis{(4-hydroxy-3-methyl)phenyl}propane, α,α'-bis(4-hydroxyphenyl)-m-diisopropylbenzene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, and the like. Two or more of these may be used. Among these, bisphenol A is preferable, and a polycarbonate resin having excellent impact strength can be obtained. On the other hand, a copolymer obtained using bisphenol A and another dihydric phenol is excellent in terms of high heat resistance or low water absorption.

[0045] Examples of the carbonate precursor include carbonyl halide, carbonic acid diester, or haloformate. Specifically, phosgene, diphenyl carbonate, or dihaloformate of dihydric phenol can be mentioned.

[0046] When producing a polycarbonate resin from the above dihydric phenol and carbonate precursor, a catalyst, a terminal stopper, an antioxidant for preventing oxidation of the dihydric phenol, etc. may be used as necessary.

[0047] The polycarbonate resin may be a branched polycarbonate resin copolymerized with a polyfunctional aromatic compound having three or more functional groups, or may be a polyester carbonate resin copolymerized with an aromatic or aliphatic (including alicyclic) difunctional carboxylic acid, or may be a copolymerized polycarbonate resin copolymerized with a difunctional alcohol (including alicyclic), or may be a polyester carbonate resin copolymerized with both such a difunctional carboxylic acid and a difunctional alcohol. Also, two or more of these polycarbonate resins may be used.

[0048] The molecular weight of the polycarbonate resin is not specified, but those having a viscosity average molecular weight of 10,000 to 50,000 are preferred. If the viscosity average molecular weight is 10,000 or more, the strength of the molded product can be further improved. More preferably, it is 15,000 or more, and even more preferably, it is 18,000 or more. On the other hand, if the viscosity average molecular weight is 50,000 or less, the moldability is improved. More preferably, it is 40,000 or less, and even more preferably, it is 30,000 or less. When using two or more polycarbonate resins, it is preferable that at least one of the viscosity average molecular weights is within the above range. In this case, as the other polycarbonate resin, it is preferable to use a polycarbonate resin having a viscosity average molecular weight exceeding 50,000, preferably exceeding 80,000. Such a polycarbonate resin has high entropy elasticity and is advantageous when used in combination with gas-assisted molding or the like. In addition, it exhibits characteristics derived from high entropy elasticity (characteristics such as drip prevention characteristics, drawdown characteristics, and characteristics that improve melt characteristics such as jetting improvement).

[0049] The viscosity average molecular weight (M) of the polycarbonate resin is obtained by inserting the specific viscosity (ηsp) determined at 20 °C from a solution prepared by dissolving 0.7 g of the polycarbonate resin in 100 ml of methylene chloride into the following formula. ηsp / c = [η] + 0.45 × [η] 2 c (where [η] is the intrinsic viscosity) [η] = 1.23 × 10 -4 M 0.83 c = 0.7.

[0050] The melt viscosity of the polycarbonate resin is not specified, but preferably it is 10 to 25,000 Pa·s at 200°C. If the melt viscosity at 200°C is 10 Pa·s or more, the strength of the molded product can be further improved. More preferably, it is 20 Pa·s or more, and even more preferably, it is 50 Pa·s or more. On the other hand, if the melt viscosity at 200°C is 25,000 Pa·s or less, the molding processability is improved. More preferably, it is 20,000 Pa·s or less, and even more preferably, it is 15,000 Pa·s or less.

[0051] As the polycarbonate resin, those commercially available such as "Iupilon" (registered trademark), "Novarex" (registered trademark) manufactured by Mitsubishi Engineering-Plastics Corporation, "Panlite" (registered trademark) manufactured by Teijin Chemicals Ltd., and "Tafron" (registered trademark) manufactured by Idemitsu Petrochemical Co., Ltd. can also be used.

[0052] In the present invention, examples of the polyarylene sulfide resin include polyphenylene sulfide (PPS) resin, polyphenylene sulfide sulfone resin, polyphenylene sulfide ketone resin, and random or block copolymers thereof. Two or more of these may be used. Among them, polyphenylene sulfide resin is particularly preferably used.

[0053] The polyarylene sulfide resin can be produced by any method, for example, a method for obtaining a polymer with a relatively low molecular weight described in Japanese Patent Publication No. 45-3368, a method for obtaining a polymer with a relatively high molecular weight described in Japanese Patent Publication No. 52-12240 and Japanese Unexamined Patent Publication No. 61-7332.

[0054] The obtained polyarylene sulfide resin may be subjected to various treatments such as crosslinking / high molecular weightization by heating in air, heat treatment in an inert gas atmosphere such as nitrogen or under reduced pressure, washing with an organic solvent, hot water, an acid aqueous solution, activation with a functional group-containing compound such as an acid anhydride, an amine, an isocyanate, and a functional group-containing disulfide compound.

[0055] The melt viscosity of the polyarylene sulfide resin is preferably 80 Pa·s or less, more preferably 20 Pa·s or less, under the conditions of 310°C and a shear rate of 1000 / second. There is no particular limitation on the lower limit, but it is preferably 5 Pa·s or more. Two or more polyarylene sulfide resins having different melt viscosities may be used in combination. The melt viscosity can be measured using a capillary graph (manufactured by Toyo Seiki Seisaku-sho, Ltd.) apparatus under the conditions of a die length of 10 mm and a die hole diameter of 0.5 to 1.0 mm.

[0056] As the polyarylene sulfide resin, polyphenylene sulfide resins marketed as "Torayna" (registered trademark) manufactured by Toray Industries, Inc., "DIC.PPS" (registered trademark) manufactured by DIC Corporation, "Durafide" (registered trademark) manufactured by Polyplastics Co., Ltd., etc. can also be used.

[0057] Carbon fiber [B] can improve the mechanical properties of the molded product due to the fiber reinforcement effect on the thermoplastic resin [A]. Furthermore, when using carbon fibers excellent in conductivity, heat conduction properties, etc., those properties can be imparted to the molded product. From the viewpoints of improving mechanical properties and the weight reduction effect of the molded product, carbon fibers such as PAN-based, pitch-based, and rayon-based are preferable, and PAN-based carbon fibers are more preferable from the viewpoint of the balance between the strength and elastic modulus of the obtained molded product. Also, for the purpose of imparting conductivity, carbon fibers coated with metals such as nickel, copper, and ytterbium are preferably used.

[0058] As the carbon fiber [B], those having a tensile elastic modulus of 250 GPa or more are preferred, those having a tensile elastic modulus of 290 GPa or more are more preferred, and those having a tensile elastic modulus of 350 GPa or more are even more preferred. When the tensile elastic modulus is 250 GPa or more, the acoustic properties of the molded product are likely to be improved. The upper limit of the tensile elastic modulus is not particularly limited, but it is preferably 650 GPa or less so that the weight average fiber length in the molded product does not become too short. The tensile elastic modulus of the carbon fiber [B] can be evaluated by the resin impregnated strand test method of JIS R7608:2004. In order to control the tensile elastic modulus of the carbon fiber [B], the carbonization temperature and the drawing ratio during the production of the carbon fiber may be adjusted.

[0059] Also, the average fiber diameter of the carbon fiber [B] is not particularly limited, but from the viewpoints of the mechanical properties and the surface appearance of the molded product, it is preferably 6 to 20 μm, more preferably 6 to 15 μm, and even more preferably 6 to 12 μm. Here, the average fiber diameter refers to the average fiber diameter of the single fiber. The number of single fibers in the case of a carbon fiber bundle is not particularly limited, but it is preferably 20,000 to 350,000, and more preferably 20,000 to 100,000 from the viewpoint of productivity.

[0060] For the purpose of improving the adhesiveness between the carbon fiber [B] and the thermoplastic resin [A] which is the matrix resin, the carbon fiber [B] may be surface-treated. Examples of the surface treatment method include electrolytic treatment, ozone treatment, ultraviolet treatment, etc.

[0061] For the purpose of preventing the carbon fiber [B] from fuzzing or improving the adhesiveness between the carbon fiber [B] and the thermoplastic resin [A] which is the matrix resin, the carbon fiber [B] may be coated with a sizing agent. By applying a sizing agent to the carbon fiber [B], the surface characteristics such as functional groups on the carbon fiber surface can be improved, and the adhesiveness and the composite overall characteristics can be improved.

[0062] Examples of sizing agents include, for example, epoxy resins, phenol resins, polyethylene glycols, polyurethanes, polyesters, emulsifiers or surfactants, etc. Two or more of these may be used. The sizing agent is preferably water-soluble or water-dispersible. An epoxy resin having excellent wettability with carbon fiber [B] is preferred, and a polyfunctional epoxy resin is more preferred.

[0063] Examples of polyfunctional epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, aliphatic epoxy resins, phenol novolac type epoxy resins, etc. Among them, an aliphatic epoxy resin that is likely to exhibit adhesiveness with the matrix resin is preferred. Due to its flexible skeleton, the aliphatic epoxy resin is likely to have a highly tough structure even with a high crosslinking density. When present between carbon fiber / matrix resin, it can make the structure flexible and difficult to peel off, thereby further improving the strength of the molded product.

[0064] Examples of polyfunctional aliphatic epoxy resins include, for example, diglycidyl ether compounds, polyglycidyl ether compounds, etc. Examples of diglycidyl ether compounds include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ethers, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, polytetramethylene glycol diglycidyl ethers, polyalkylene glycol diglycidyl ethers, etc. Examples of polyglycidyl ether compounds include glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ethers, sorbitol polyglycidyl ethers, arabitol polyglycidyl ethers, trimethylolpropane polyglycidyl ethers, trimethylolpropane glycidyl ethers, pentaerythritol polyglycidyl ethers, polyglycidyl ethers of aliphatic polyhydric alcohols, etc.

[0065] Among aliphatic epoxy resins, trifunctional or higher aliphatic epoxy resins are preferred, and aliphatic polyglycidyl ether compounds having three or more highly reactive glycidyl groups are more preferred. Aliphatic polyglycidyl ether compounds have a good balance of flexibility, crosslink density, and compatibility with the matrix resin, and can further improve adhesion. Among these, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ethers, polyethylene glycol glycidyl ethers, and polypropylene glycol glycidyl ethers are even more preferred.

[0066] The amount of sizing agent attached is preferably 0.01 to 10% by weight in 100% by weight of the carbon fiber bundle containing the sizing agent and carbon fiber [B]. If the amount of sizing agent attached is 0.01% by weight or more, the adhesion to the thermoplastic resin [A] can be further improved. The amount of sizing agent attached is more preferably 0.05% by weight or more, and even more preferably 0.1% by weight or more. On the other hand, if the amount of sizing agent attached is 10% by weight or less, the physical properties of the thermoplastic resin [A] can be maintained at a higher level. The amount of sizing agent attached is more preferably 5% by weight or less, and even more preferably 2% by weight or less.

[0067] The means for applying the sizing agent is not particularly limited. For example, a sizing treatment liquid in which the sizing agent is dissolved (including dispersion) in a solvent (including the dispersion medium in the case of dispersion) is prepared, and after applying the sizing treatment liquid to the carbon fiber [B], the solvent is dried and vaporized and removed. Examples of the method for applying the sizing treatment liquid to the carbon fiber [B] include a method of immersing the carbon fiber [B] in the sizing treatment liquid through a roller, a method of bringing the carbon fiber [B] into contact with a roller coated with the sizing treatment liquid, and a method of spraying the sizing treatment liquid in a mist form onto the carbon fiber [B]. Also, either a batch type or a continuous type may be used, but a continuous type with good productivity and small variation is preferred. At this time, it is preferable to adjust the sizing treatment liquid concentration, temperature, yarn tension, etc. so that the adhesion amount of the sizing agent to the carbon fiber [B] becomes uniform within an appropriate range. Further, it is more preferable to vibrate the carbon fiber [B] with ultrasonic waves when applying the sizing treatment liquid.

[0068] The molded article of the present invention can further contain a compound [C] having a reactive functional group. The compound [C] can react with the thermoplastic resin [A] by having a reactive functional group. Here, the reactive functional group is preferably at least one functional group selected from a carboxy group, a hydroxy group, an epoxy group, an amino group, an oxazoline group, an isocyanate group, and a carbodiimide group.

[0069] The compound having a carboxy group is not particularly limited, and examples thereof include a method of copolymerizing a vinyl monomer having a carboxy group or an anhydrous carboxy group such as acrylic acid, methacrylic acid, maleic acid, maleic acid monoethyl ester, maleic anhydride, phthalic acid, and itaconic acid, a polymerization initiator having a carboxy group such as γ,γ'-azobis(γ-cyanovaleric acid), α,α'-azobis(α-cyanoethyl)-p-benzoic acid, and succinic peroxide, and / or a method of copolymerizing using a polymerization degree regulator having a carboxy group such as thioglycolic acid, α-mercaptopropionic acid, β-mercaptopropionic acid, α-mercapto-isobutyric acid, and 2,3- or 4-mercaptobenzoic acid, and a method of saponifying a copolymer of a (meth)acrylic acid ester monomer such as methyl methacrylate or methyl acrylate and a predetermined vinyl monomer with an alkali, etc. can be used.

[0070] The compound having a hydroxy group is not particularly limited, and examples thereof include a method of copolymerizing a vinyl monomer having a hydroxyl group such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 2,3,4,5,6-pentahydroxyhexyl acrylate, 2,3,4,5,6-pentahydroxyhexyl methacrylate, 2,3,4,5-tetrahydroxypentyl acrylate, 2,3,4,5-tetrahydroxypentyl methacrylate, 3-hydroxy-1-propene, 4-hydroxy-1-butene, cis-4-hydroxy-2-butene, trans-4-hydroxy-2-butene, 3-hydroxy-2-methyl-1-propene, cis-5-hydroxy-2-pentene, trans-5-hydroxy-2-pentene, 4,4-dihydroxy-2-butene, etc., and a compound having a hydroxy group such as polyethylene glycol can be used.

[0071] The compound having an epoxy group is not particularly limited. For example, a method of copolymerizing a monomer having an epoxy group such as glycidyl acrylate, glycidyl methacrylate, glycidyl ethacrylate, glycidyl itaconate, allyl glycidyl ether, styrene-p-glycidyl ether, and p-glycidylstyrene, or an epoxy resin can be used. Among them, glycidyl ether substituted with an alkyl group is preferably used because it has excellent reactivity with the dendritic polyester and can effectively improve the dispersibility.

[0072] The compound having an amino group is not particularly limited. For example, a method of copolymerizing a monomer having an amino group and its derivatives such as acrylamide, methacrylamide, N-methylacrylamide, butoxymethylacrylamide, N-propylmethacrylamide, aminoethyl acrylate, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, phenylaminoethyl methacrylate, cyclohexylaminoethyl methacrylate, N-vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine, p-aminostyrene can be used.

[0073] The compound having an oxazoline group is not particularly limited. For example, a method of copolymerizing a monomer having an oxazoline group such as 2-isopropenyl-oxazoline, 2-vinyl-oxazoline, 2-acroyl-oxazoline, and 2-styryl-oxazoline can be used.

[0074] The compound having an isocyanate group is not particularly limited, and the same as above, a method of copolymerizing monomers having various functional groups or an organic compound modified with a monomer having a functional group can be used. Examples of the compound having an isocyanate group include 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), 2,4-tolylene diisocyanate and its isomers or a mixture of isomers, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tolidine diisocyanate, naphthalene diisocyanate, polyphenylmethane triisocyanate and other polyisocyanates, and one or more of them can be used.

[0075] Examples of the compound having a carbodiimide group, that is, a carbodiimide compound, include polycarbodiimide, and aliphatic polycarbodiimide and aromatic polycarbodiimide can be mentioned. From the viewpoint of the affinity and reactivity between the thermoplastic resin [A] and the carbon fiber [B], aliphatic polycarbodiimide is preferably used.

[0076] The aliphatic polycarbodiimide compound is a homopolymer or copolymer having a repeating unit represented by the general formula -N=C=N-R 3 - (wherein R 3 represents a divalent organic group of an alicyclic compound such as cyclohexylene, or a divalent organic group of an aliphatic compound such as methylene, ethylene, propylene, or methylethylene) as a main constituent unit, preferably containing 70 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more of the repeating unit.

[0077] As the compound [C], polycarbodiimide is preferably used from the viewpoint of interfacial adhesion between the thermoplastic resin [A] and the carbon fiber [B].

[0078] The addition amount of compound [C] is preferably in the range of 0.1 to 10 parts by weight, more preferably in the range of 0.5 to 8 parts by weight, and still more preferably in the range of 1 to 5 parts by weight, based on 100 parts by weight in total of components [A], [B], and [C]. By setting the addition amount to 0.1 part by weight or more, the adhesiveness between the thermoplastic resin [A] and the carbon fiber [B] can be improved, and it becomes possible to improve the interfacial shear strength and further the vibration persistence. Also, by setting the addition amount to 10 parts by weight or less, it is preferable because the retention stability of the resin composition can be maintained.

[0079] Compound [C] in the present invention is appropriately selected according to the combination with the thermoplastic resin [A] which is the matrix resin. For example, when the thermoplastic resin [A] is a polypropylene resin, a compound having a carboxy group is preferable as compound [C]. When the thermoplastic resin [A] is a polycarbonate resin, a compound having an epoxy group is preferable as compound [C]. When the thermoplastic resin [A] is a polyamide resin, a compound having an epoxy group or a compound having a carboxy group is preferable as compound [C]. When the thermoplastic resin [A] is a polyarylene sulfide resin, a compound having an isocyanate group or a carbodiimide group is preferable as compound [C].

[0080] The molded article of the present invention may contain other components in addition to the above components [A], [B], and [C] as long as the object of the present invention is not impaired. Examples of the other components include a resin [D] having a melt viscosity at 200°C lower than that of the thermoplastic resin [A], a flame retardant [E], a heat conduction filler [F], and carbon black [G]. By containing the resin [D], the dispersibility of the carbon fiber [B] can be improved. By containing the flame retardant [E], the flame retardancy of the molded article can be improved. By containing the heat conduction filler [F], the heat conductivity of the molded article can be improved. By containing the carbon black [G], the conductivity and black color tone of the molded article can be further improved.

[0081] Resin [D] is a resin with a lower melt viscosity at 200 °C than thermoplastic resin [A]. By containing resin [D], the dispersibility of carbon fiber [B] can be further improved and the fluidity during molding can be further improved during the production of the molding material described later or when molding a molded product using the molding material. Thereby, the vibration persistence of the molded product can be further improved.

[0082] The melt viscosity of resin [D] at 200 °C is preferably 0.01 to 10 Pa·s. If the melt viscosity at 200 °C is 0.01 Pa·s or more, the breakage starting from resin [D] can be more suppressed and the mechanical properties of the molded product can be further improved. More preferably, it is 0.05 Pa·s or more, and even more preferably 0.1 Pa·s or more. On the other hand, if the melt viscosity at 200 °C is 10 Pa·s or less, the dispersibility of carbon fiber [B] in the obtained molded product can be further improved. More preferably, it is 5 Pa·s or less, and even more preferably 2 Pa·s or less. Here, the melt viscosity of resin [D] at 200 °C can be measured by a viscoelasticity measuring instrument at 0.5 Hz using a 40 mm parallel plate.

[0083] As resin [D], those with high affinity for thermoplastic resin [A] are preferred. By selecting resin [D] with high affinity for thermoplastic resin [A], in the molded product, since it is efficiently compatible with thermoplastic resin [A], the dispersibility of carbon fiber [B] can be further improved.

[0084] The blending amount of resin [D] is preferably 0.1 to 12 parts by weight with respect to a total of 100 parts by weight of the above components [A] to [C]. If the blending amount of resin [D] is 0.1 part by weight or more, the dispersibility of carbon fiber [B] in the molded product can be further improved. The blending amount of resin [D] is more preferably 2 parts by weight or more. On the other hand, when the blending amount of resin [D] is 12 parts by weight or less, a decrease in the mechanical properties of the molded product can be suppressed. The blending amount of resin [D] is preferably 10 parts by weight or less.

[0085] As the resin [D], at least one resin selected from the group consisting of terpene resins, epoxy resins, phenolic resins, and cyclic polyphenylene sulfide is preferable.

[0086] The resin [D] is appropriately selected according to the combination with the thermoplastic resin [A] which is the matrix resin. For example, if the molding temperature is in the range of 150 to 270°C, a terpene resin is preferably used. If the molding temperature is in the range of 270 to 320°C, an epoxy resin is preferably used. Specifically, when the thermoplastic resin [A] is a polypropylene resin, the resin [D] is preferably a terpene resin. When the thermoplastic resin [A] is a polycarbonate resin or a polyphenylene sulfide resin, the resin [D] is preferably an epoxy resin. When the thermoplastic resin [A] is a polyamide resin, the resin [D] is preferably a terpene phenol resin.

[0087] The epoxy resin preferably used as the resin [D] is a compound having two or more epoxy groups, substantially free of a curing agent, and not undergoing curing by so-called three-dimensional crosslinking even when heated. It is preferable that the epoxy resin has a glycidyl group because it easily interacts with the carbon fiber [B] and is easily impregnated. Further, the dispersibility of the carbon fiber [B] during molding can be further improved.

[0088] Here, examples of the compound having a glycidyl group include glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, and alicyclic epoxy resins. Two or more of these may be used. Among them, glycidyl ether type epoxy resins are preferable, and bisphenol A type epoxy resins and bisphenol F type epoxy resins are more preferable because of their excellent balance between viscosity and heat resistance.

[0089] In addition, the number average molecular weight of the epoxy resin used as the resin [D] is preferably 200 to 5000. If the number average molecular weight of the epoxy resin is 200 or more, the mechanical properties of the molded product can be further improved. More preferably, it is 800 or more, and even more preferably, it is 1000 or more. On the other hand, if the number average molecular weight of the epoxy resin is 5000 or less, it has excellent impregnation properties with the carbon fiber [B] and can further improve the dispersibility of the carbon fiber [B]. More preferably, it is 4000 or less, and even more preferably, it is 3000 or less. The number average molecular weight of the epoxy resin can be measured using gel permeation chromatography (GPC).

[0090] Examples of the terpene resin include polymers or copolymers obtained by polymerizing terpene monomers, optionally together with aromatic monomers or the like, in the presence of a Friedel-Crafts type catalyst in an organic solvent.

[0091] Examples of the terpene monomer include monocyclic monoterpenes such as α-pinene, β-pinene, dipentene, d-limonene, myrcene, alloocimene, ocimene, α-farnesene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol, sabinene, paramethylenedienes, and carenes. Examples of the aromatic monomer include styrene and α-methylstyrene.

[0092] Among them, terpene monomers selected from α-pinene, β-pinene, dipentene, and d-limonene are preferred because of their excellent compatibility with the thermoplastic resin [A]. Furthermore, homopolymers of terpene monomers selected from these are more preferred. In addition, hydrogenated terpene resins obtained by subjecting terpene resins to a hydrogenation treatment are preferred because they have even better compatibility with the thermoplastic resin [A], particularly polypropylene resins.

[0093] Also, the glass transition temperature of the terpene resin is not particularly limited, but is preferably 30 to 100°C. When the glass transition temperature is 30°C or higher, the resin [D] has excellent handleability during molding. Also, when the glass transition temperature is 100°C or lower, the fluidity of the resin [D] during molding can be moderately suppressed, and the moldability can be improved.

[0094] Also, the number average molecular weight of the terpene resin is preferably 200 to 5000. If the number average molecular weight is 200 or more, the flexural strength and tensile strength of the molded product can be further improved. Also, if the number average molecular weight is 5000 or less, the viscosity of the terpene resin is moderately low, so it has excellent impregnability and can further improve the dispersibility of carbon fiber [B] in the molded product. The number average molecular weight of the terpene resin can be measured using gel permeation chromatography (GPC).

[0095] The terpene phenol resin is obtained by reacting a terpene monomer and phenols with a catalyst. Here, as the phenols, those having 1 to 3 alkyl groups, halogen atoms and / or hydroxyl groups on the benzene ring of phenol are preferably used. Specific examples thereof include cresol, xylenol, ethylphenol, butylphenol, t-butylphenol, nonylphenol, 3,4,5-trimethylphenol, chlorophenol, bromophenol, chlorocresol, hydroquinone, resorcinol, orcinol, and the like. Two or more of these may be used. Among these, phenol and cresol are preferred.

[0096] Further, the number average molecular weight of the terpene phenol resin is preferably 200 to 5,000. If the number average molecular weight is 200 or more, the mechanical properties of the molded product can be further improved. Also, if the number average molecular weight is 5,000 or less, the viscosity of the terpene phenol resin is moderately low, so it has excellent impregnation properties and can further improve the dispersibility of carbon fiber [B] in the molded product. The number average molecular weight of the terpene phenol resin can be measured using gel permeation chromatography (GPC).

[0097] As described above, from the viewpoint of improving flame retardancy, the molded product of the present invention can contain a flame retardant [E]. Examples of the type of flame retardant include phosphorus-based flame retardants. The phosphorus-based flame retardant [E] exhibits flame retardancy because it forms a dense char on the surface of the molded product by promoting dehydration carbonization, blocks heat and oxygen, and prevents the propagation of flames.

[0098] Examples of the phosphorus-based flame retardant [E] include phosphate ester compounds such as triphenyl phosphate, tricresyl phosphate, trimethyl phosphate, triethyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, and other aromatic phosphate esters; halogen-containing phosphate ester compounds such as tris(dichloropropyl) phosphate, tris(chloroethyl) phosphate, and tris(chloropropyl) phosphate; condensed phosphate ester compounds, polyphosphates, and red phosphorus-based compounds. These can be used alone or in combination of two or more. Among them, condensed phosphate ester compounds are preferable in terms of the balance between heat resistance and flame retardancy.

[0099] The blending amount of the phosphorus-based flame retardant [E] is preferably 1 to 15 parts by weight with respect to 100 parts by weight in total of components [A] to [C]. If the blending amount is 5 parts by weight or more, the flame retardancy of the molded product increases. The blending amount is preferably 7 parts by weight or more. On the other hand, when the blending amount is 15 parts by weight or less, the mechanical properties of the molded product are improved. The blending amount is preferably 10 parts by weight or less.

[0100] As the heat conductive filler [F], a filler having heat conductive properties other than carbon fiber [B] is selected. Examples of the filler shape include non-fibrous shapes such as plate-like, flaky, granular, irregular, and crushed products. Specifically, mica, talc, kaolin, silica, calcium carbonate, glass beads, glass flakes, glass microballoons, clay, molybdenum disulfide, wollastonite, calcium polyphosphate, graphite, metal powder, metal flakes, metal ribbons, metal oxides (alumina, zinc oxide, titanium oxide, etc.), carbon powder, graphite, carbon flakes, flaky carbon, carbon nanotubes, etc. may be mentioned. Two or more of these may be contained. Specific examples of the metal constituting the metal powder, metal flakes, and metal ribbon include silver, nickel, copper, zinc, aluminum, stainless steel, iron, brass, chromium, tin, etc.

[0101] The blending amount of the heat conductive filler [F] is preferably 1 to 40 parts by weight with respect to 100 parts by weight in total of the components [A] to [C]. If the blending amount is 1 part by weight or more, the heat conductive properties of the molded product will be enhanced. The blending amount is preferably 10 parts by weight or more. On the other hand, if the blending amount is 40 parts by weight or less, the mechanical properties of the molded product will be improved. The blending amount is preferably 30 parts by weight or less.

[0102] The molded product of the present invention may contain carbon black [G] within a range that does not impair the object of the present invention. When carbon black [G] is blended, the conductivity is further improved. The higher the conductivity, the higher the property of reflecting electromagnetic waves, so the electromagnetic wave shielding property is improved. In addition, since carbon black is also a coloring agent, the black color tone on the surface of the molded product can be further enhanced, and the appearance quality of the molded product is improved. Examples of the carbon black [G] include furnace black, acetylene black, thermal black, channel black, ketjen black, etc. Two or more of these may be contained.

[0103] The compounding amount of these carbon blacks [G] is preferably 0.1 part by weight or more and 15 parts by weight or less with respect to 100 parts by weight in total of components [A] to [C]. When the compounding amount is 0.1 part by weight or more, the conductivity, electromagnetic wave shielding property, and black color tone of the molded article are improved. When the compounding amount is 15 parts by weight or less, the generation of aggregation due to the thickening of the resin composition is suppressed, and the decrease in fluidity is suppressed, so that the appearance quality and mechanical properties of the molded article are improved. Preferably, the compounding amount is in the range of 0.5 to 10 parts by weight, and more preferably in the range of 1 to 7 parts by weight.

[0104] Next, a fiber-reinforced thermoplastic resin molding material (hereinafter, may be referred to as "molding material") suitable for obtaining the molded article of the present invention will be described in detail. In the present invention, the "molding material" means a raw material used when obtaining a molded article using injection molding or the like.

[0105] As the molding material, with respect to 100 parts by weight in total of the thermoplastic resin [A] and the carbon fiber [B], the thermoplastic resin [A] is contained in an amount of 50 to 95 parts by weight (50 parts by weight or more and 95 parts by weight or less), and the carbon fiber [B] is contained in an amount of 5 to 50 parts by weight (5 parts by weight or more and 50 parts by weight or less).

[0106] As the form of the molding material, it is preferable that the outside of the fiber bundle [H] in which the resin [D] is impregnated into the carbon fiber [B] is covered with the thermoplastic resin [A] (or a resin composition containing the thermoplastic resin [A]). In the following description, for the sake of simplicity, the resin composition containing the thermoplastic resin [A] is also simply referred to as the thermoplastic resin [A].

[0107] Here, the "covered structure" refers to a structure in which the thermoplastic resin [A] is disposed on the surface of the fiber bundle [H] and the two are adhered. Near the boundary between the fiber bundle [H] and the thermoplastic resin [A], the thermoplastic resin [A] may be in a state of entering a part of the fiber bundle [H]. That is, a state in which a part of the thermoplastic resin [A] is impregnated into the carbon fiber [B] constituting the fiber bundle [H] near the boundary, or a state in which it is compatible with the resin [D] may be sufficient.

[0108] As a method for coating the surface of the fiber bundle [H] with the thermoplastic resin [A], a method of cooling and solidifying the molten thermoplastic resin [A] after arranging it in contact with the surface of the fiber bundle [H] is preferable. Although not particularly limited, more specifically, a method of arranging the thermoplastic resin [A] continuously around the fiber bundle [H] using an extruder and a coating die for an electric wire coating method, or arranging the film-shaped thermoplastic resin [A] melted from one side or both sides of the fiber bundle [H] flattened by a roll or the like using an extruder and a T-die, and integrating them with a roll or the like can be mentioned.

[0109] Figures 2 and 3 are schematic views showing an example of a preferable cross-sectional form of the molding material used in the present invention. Reference numeral 1 indicates the thermoplastic resin [A], reference numeral 2 indicates the carbon fiber [B], reference numeral 3 indicates the compound [C], reference numeral 4 indicates the resin [D], and reference numeral 5 indicates the fiber bundle [H].

[0110] The cross-sectional form of the molding material is not limited to that shown in the figure as long as at least a part outside the fiber bundle [H] is coated with a resin composition containing the thermoplastic resin [A] or a resin composition containing the thermoplastic resin [A].

[0111] As shown in the longitudinal cross-sectional form of FIG. 2, the cross-section of the molding material preferably has a configuration in which the fiber bundle [H] 5 as the core material is sandwiched and arranged in layers by the resin compositions (1, 3) containing the thermoplastic resin [A]. Further, as shown in the cross-sectional form of FIG. 3, a configuration in which the fiber bundle [H] 5 is used as a core structure and the resin compositions (1, 3) containing the thermoplastic resin [A] cover the periphery thereof in a core-sheath structure is also preferable. Also, a configuration in which a plurality of fiber bundles [H] (5) are arranged so as to be covered with the resin compositions (1, 3) containing the thermoplastic resin [A] as shown in FIG. 4 is also preferable. In that case, the number of fiber bundles [H] is preferably about 2 to 6. Further, FIG. 1 is a schematic view showing an example of the cross-sectional form of the fiber bundle [H] in the present invention. In the aspect of FIG. 1, the resin [D] fills the space between the individual single fibers of the carbon fiber [B] in the fiber bundle [H]. That is, it is a state in which each single fiber of the carbon fiber [B] is dispersed like an island in the sea of the resin [D]. Here, the longitudinal cross-section means a cross-section on a plane including the axial direction, and the cross-section means a cross-section on a plane perpendicular to the axial direction. Also, when the molding material is columnar such as a pellet, for example, the axial direction refers to the axis of the column.

[0112] In the molding material, it is preferable that each single fiber of the carbon fiber [B] is arranged substantially in parallel in the axial direction (the same direction) of the molding material. Also, it is preferable that the length of the carbon fiber [B] is substantially the same as the length of the molding material.

[0113] As used herein, "arranged substantially in parallel" means a state in which the axis of the long axis of carbon fiber [B] and the axis of the long axis of the molding material are oriented in the same direction. The angle formed by the axes is preferably 20° or less, more preferably 10° or less, and even more preferably 5° or less. Also, "substantially the same length" means that the carbon fiber [B] is not intentionally cut inside the molding material, and that carbon fiber [B] significantly shorter than the total length of the molding material is not substantially included. In particular, although the amount of carbon fiber [B] shorter than the total length of the molding material is not limited, the content of carbon fiber [B] having a length of 50% or less of the total length of the molding material is preferably 30% by mass or less, and more preferably 20% by mass or less, of the total carbon fiber [B]. When the carbon fiber [B] has substantially the same length as the molding material, the length of the carbon fiber in the resulting molded product can be increased, and the vibration persistence can be further improved. The lengths of the carbon fiber [B] and the molding material are preferably 14 mm or less and 3 mm or more, and more preferably 11 mm or less and 5 mm or more. The molding material preferably maintains a substantially uniform cross-sectional shape in the longitudinal direction and is continuous.

[0114] Next, a method for producing the molding material will be described.

[0115] The method for impregnating the carbon fiber [B] with the resin [D] to obtain the fiber bundle [H] is not particularly limited. For example, the method includes a step (I) of supplying the resin [D] to the carbon fiber [B] and bringing the resin [D] into contact with the carbon fiber [B] in a molten state at 100 to 300°C to adhere the resin [D] to the carbon fiber [B], and a step (II) of heating the carbon fiber [B] to which the resin [D] is adhered to impregnate the carbon fiber [B] with the resin [D].

[0116] In the above step (I), the method of supplying the resin [D] and adhering it to the carbon fiber [B] is not particularly limited. For example, known methods used when applying an oil agent, sizing agent, or matrix resin to the carbon fiber [B] can be used. Among them, dipping or coating is preferably used.

[0117] Here, dipping refers to a method of supplying resin [D] to a melting bath with a pump and passing carbon fiber [B] through the melting bath. By immersing the carbon fiber [B] in the resin [D] within the melting bath, the resin [D] can be surely adhered to the carbon fiber [B]. Further, coating refers to a method of applying resin [D] to the carbon fiber [B] using coating means such as a reverse roll, a forward rotation roll, a kiss roll, a spray, or a curtain. At this time, the resin [D] melted by a pump is supplied to the roll, and the melt of the resin [D] is applied to the carbon fiber [B]. The reverse roll is a method in which two rolls rotate in opposite directions to each other and the melted resin [D] is applied onto the roll, and the forward rotation roll is a method in which two rolls rotate in the same direction and the melted resin [D] is applied onto the roll. Usually, in the reverse roll and the forward rotation roll, a method is used in which the carbon fiber [B] is sandwiched between two rolls, and further rolls are installed to surely adhere the resin [D]. On the other hand, the kiss roll is a method of adhering the resin [D] only by contacting the carbon fiber [B] and the roll. Therefore, the kiss roll is preferably used when the viscosity is relatively low. Whichever roll method is used, a predetermined amount of the heat-melted resin [D] is applied and the carbon fiber [B] is run while being in contact, so that a predetermined amount of the resin [D] can be adhered per unit length of the fiber. The spray utilizes the principle of atomization and is a method of spraying the melted resin [D] in an atomized state onto the carbon fiber [B], and the curtain is a method of applying the melted resin [D] by allowing it to naturally drop from small holes or by overflowing it from a melting tank. Since it is easy to adjust the amount required for coating, the loss of the resin [D] can be reduced.

[0118] Also, the melting temperature (temperature in the melting bath) when supplying the resin [D] is preferably 100 to 300°C. If the melting temperature is 100°C or higher, the viscosity of the resin [D] can be appropriately suppressed, and uneven adhesion can be suppressed. The melting temperature is more preferably 150°C or higher. On the other hand, if the melting temperature is 300°C or lower, thermal decomposition of the resin [D] can be suppressed even when manufactured for a long time. The melting temperature is more preferably 250°C or lower. By bringing the resin [D] into contact with the carbon fiber [B] in a molten state at 100 to 300°C, the resin [D] can be stably supplied.

[0119] Next, the process (process (II)) of heating and impregnating the carbon fiber [B] with the resin [D] obtained in process (I) will be described. Specifically, for the carbon fiber [B] with the resin [D] attached, at the temperature at which the resin [D] melts, operations such as applying tension with a roll or bar, repeating widening, converging, applying pressure or vibration are performed to impregnate the resin [D] into the interior of the carbon fiber [B]. As a more specific example, a method can be mentioned in which the carbon fiber [B] with the resin [D] attached is passed in contact with the surfaces of a plurality of heated rolls or bars to perform widening and the like. Among them, a method of impregnating using a die, a draw roll, a roll press or a double belt press is preferably used. Here, a die is a die whose diameter narrows in the advancing direction, and it is a die that scrapes off the resin [D] adhering excessively while converging the carbon fiber [B] and promotes impregnation at the same time. Also, a draw roll is a roller that applies tension to the carbon fiber [B] with a roller, and at the same time scrapes off the resin [D] adhering excessively and promotes impregnation. Also, a roll press is a device that continuously removes the air inside the carbon fiber [B] with the pressure between two rolls and promotes impregnation at the same time. A double belt press is a device that promotes impregnation by pressing from above and below the carbon fiber [B] through a belt.

[0120] In step (II), it is preferable that 80 to 100% by weight of the supply amount of resin [D] is impregnated into carbon fiber [B]. Since it directly affects the yield, from the viewpoints of economy and productivity, the higher the impregnation amount with respect to the supply amount, the more preferable. The impregnation amount is more preferably 85 to 100% by weight, and even more preferably 90 to 100% by weight. Also, if the impregnation amount is 80% by weight or more, in addition to the economic viewpoint, generation of volatile components due to resin [D] in step (II) can be suppressed, and generation of voids inside fiber bundle [H] can be suppressed.

[0121] In step (II), it is preferable that the maximum temperature of resin [D] is 150 to 400°C. If the maximum temperature is 150°C or higher, resin [D] can be sufficiently melted and impregnated more effectively. The maximum temperature is more preferably 180°C or higher, and even more preferably 200°C or higher. On the other hand, if the maximum temperature is 400°C or lower, undesirable side reactions such as decomposition reaction of resin [D] can be suppressed. The maximum temperature is more preferably 380°C or lower, and even more preferably 350°C or lower.

[0122] The heating method in step (II) is not particularly limited, but specifically, examples can include a method using a heated chamber, a method of simultaneously heating and pressurizing using a hot roller, etc.

[0123] Also, from the viewpoint of suppressing generation of undesirable side reactions such as crosslinking reaction and decomposition reaction of resin [D], it is preferable to heat in a non-oxidizing atmosphere. Here, the non-oxidizing atmosphere refers to an atmosphere with an oxygen concentration of 5% by volume or less, preferably 2% by volume or less, and more preferably an atmosphere containing no oxygen, that is, an inert gas atmosphere such as nitrogen, helium, argon, etc. In particular, from the viewpoints of economy and ease of handling, a nitrogen atmosphere is preferable.

[0124] Also, before the above steps (I) and (II), a step of pre-opening the carbon fiber [B] bundle may be provided. Opening the fiber means an operation of separating the converged carbon fiber bundle, and an effect of further enhancing the impregnation property of the resin [D] can be expected. By opening the fiber, the thickness of the carbon fiber bundle becomes thinner. The width of the carbon fiber bundle before opening is b 1 (mm), the thickness is a 1 (μm), the width of the carbon fiber bundle after opening is b 2 (mm), the thickness is a 2 (μm). When this is the case, the opening ratio = (b 2 / a 2 ) / (b 1 / a 1 ) is preferably 2.0 or more, and more preferably 2.5 or more.

[0125] The method for opening the carbon fiber bundle is not particularly limited. For example, a method of alternately passing through concavo-convex rolls, a method of using a drum-shaped roll, a method of applying a tension fluctuation to an axial vibration, a method of fluctuating the tension of the carbon fiber bundle by two friction bodies reciprocating vertically, a method of blowing air onto the carbon fiber bundle, etc. can be used.

[0126] By coating such a fiber bundle [H] with a thermoplastic resin [A] or a resin composition containing the thermoplastic resin [A], a desired molding material can be obtained.

[0127] The molding material may contain other components in addition to the above components [A] to [D] as long as the object of the present invention is not impaired. Examples of other components include the above-mentioned flame retardant [E], heat conduction filler [F], carbon black [G], etc. Specific examples and preferred blending amounts of components [E] to [G] are the same as those exemplified for the molded article of the present invention.

[0128] When the molding material has a core-sheath structure, the components [E] to [G] may be contained in the core structure, may be contained in the sheath structure, or may be contained in both.

[0129] When obtaining a molding material by coating the surface of a fiber bundle [H] with a thermoplastic resin [A], it is preferable that the thermoplastic resin [A] or a resin composition containing the thermoplastic resin [A] is melt-kneaded at a resin pressure of 1.0 MPa or more. Here, the resin pressure is the value measured by a resin pressure gauge attached to the melt-kneading apparatus, and the gauge pressure is taken as the resin pressure. The resin pressure is not particularly limited as long as it is 1.0 MPa or more, but it is preferably used in the range of 1 to 10 MPa, and more preferably in the range of 1.5 to 7 MPa because the deterioration of the resin is small.

[0130] The method for adjusting the resin pressure during melt-kneading is not particularly limited. For example, improving the resin viscosity by lowering the melt-kneading temperature, selecting a polymer with a molecular weight such that the target resin pressure is achieved, reverse full flight, resin retention by changing the screw arrangement such as introducing a kneading block, increasing the polymer filling rate in the barrel, increasing the screw rotation speed, improving the resin viscosity by mixing an arbitrary additive, and supercritical states such as introducing carbon dioxide gas can be mentioned.

[0131] The above-described molding material is formed into a molded product by a method such as injection molding or press molding. From the viewpoint of the handleability of the molding material, it is preferable that the fiber bundle [H] and the thermoplastic resin [A] or the resin composition containing the thermoplastic resin [A] remain adhered and do not separate until molding, and maintain the shape as described above. In the fiber bundle [H] and the thermoplastic resin [A] or the resin composition containing the thermoplastic resin [A], since the shape (size, aspect ratio), specific gravity, and mass are completely different, classification may occur during the transportation and handling of the material until molding and during the material transfer in the molding process, resulting in variations in the mechanical properties of the molded product, a decrease in fluidity causing mold clogging, or blocking in the molding process. However, in the case of the core-sheath structure arrangement as illustrated in Figure 3, the resin composition containing the thermoplastic resin [A] or the thermoplastic resin [A] restrains the fiber bundle [H], enabling stronger composite formation.

[0132] The formed material may be continuous or cut into a certain length as long as it maintains substantially the same cross-sectional shape in its axial direction. The length of the formed material is preferably cut to a length in the range of 11 mm or less and 5 mm or more. By adjusting to such a length, the fluidity and handleability during forming can be sufficiently enhanced. A particularly preferred embodiment of the formed material cut to an appropriate length is exemplified by long fiber pellets for injection molding.

[0133] The forming method for obtaining the formed product of the present invention is not particularly limited, and examples thereof include forming methods excellent in productivity such as injection molding, autoclave molding, press molding, filament winding molding, and stamping molding. These can also be used in combination. Further, integral molding such as insert molding and outsert molding can also be applied. Among these, a molding method using a mold is preferable, and in particular, a molding method using an injection molding machine can continuously obtain stable formed products. The conditions for injection molding are not particularly defined. For example, injection time: 0.5 seconds to 15 seconds, more preferably 1 second to 10 seconds; back pressure: 0.1 MPa to 20 MPa, more preferably 2 to 15 MPa, still more preferably 3 MPa to 10 MPa; holding pressure: 1 MPa to 150 MPa, more preferably 5 MPa to 100 MPa; holding pressure time: 1 second to 20 seconds, more preferably 5 seconds to 20 seconds; cylinder temperature: 200 °C to 320 °C; mold temperature: 20 °C to 100 °C are preferable. Here, the cylinder temperature indicates the temperature of the part of the injection molding machine that heats and melts the formed material, and the mold temperature indicates the temperature of the mold into which the resin is injected to form a predetermined shape. By appropriately selecting these conditions, particularly the injection time, back pressure, and mold temperature, the weight average fiber length [L w of the carbon fiber [B] in the formed product can be adjusted to the aforementioned preferable range.

[0134] Examples of the uses of the molded article of the present invention include various modules such as instrument panels, door beams, undercovers, lamp housings, pedal housings, radiator supports, spare tire covers, and front ends; cylinder head covers, bearing retainers, intake manifolds, pedals, and other automotive parts and members, and outer panels; landing gear pods, winglets, spoilers, edges, ladders, fairings, ribs, and other aircraft-related parts and members, and outer panels; parts of household and office electrical products such as telephones, facsimile machines, VTRs, copiers, TVs, microwave ovens, toiletries, refrigerators, and air conditioners; members for electric and electronic devices such as casings for personal computers, digital cameras, mobile phones, and keyboard supports that support keyboards inside personal computers; related parts and members and outer panels of acoustic devices such as speakers and microphones; outer wall members of acoustic equipment; bicycle parts, fishing rods for fishing, reels, and heads and shafts of golf clubs, and other sports-related parts and members and exterior parts.

[0135] Since the molded article of the present invention is excellent in vibration persistence and acoustic characteristics, among the above applications, it is suitably used for acoustic devices and acoustic equipment. Also, in some sports-related parts and members such as fishing rods, golf club heads and shafts, there are those in which vibration persistence and acoustic characteristics are useful as added values. For example, for the outer plate of an acoustic device, since it is excellent in vibration persistence, the vibration caused by sound resonates without being impaired by the outer plate, so that the sound does not get trapped inside the outer plate and a clear sound quality can be obtained. Also, for fishing rods and golf club shafts, since they are excellent in vibration persistence, the fine vibrations at the tips of fishing rods and golf clubs can be transmitted to the user's hands without being impaired, so that fishing rods and golf clubs with excellent feeling and added value can be obtained. For golf club heads as well, similar to the outer plate of the acoustic device described above, since it is excellent in vibration persistence, the vibration caused by the hitting sound when hitting the ball is discharged outside without being impaired inside the head, and the hitting sound does not get trapped inside the head, so the acoustic characteristics of the hitting sound are considered to be excellent. Furthermore, in some of electrical / electronic devices, OA devices, household appliances, automotive parts, etc. other than acoustic devices, excellent vibration persistence and acoustic characteristics may be required. The molded article of the present invention can be suitably used for all these applications where excellent vibration persistence and acoustic characteristics are required.

Examples

[0136] Hereinafter, the present invention will be described in detail with reference to examples, but the following examples do not limit the present invention. Note that Examples 1-4, 15-18 are currently reference examples, and Examples 5-14, 19-20 are the examples of the present invention. First, the evaluation methods for various characteristics will be described.

[0137] (1) Weight average fiber length of carbon fiber [B] in the molded article Test pieces with dimensions of 80 mm × 10 mm × 4 mm thick obtained from each example and comparative example were notched with a notch angle of 45° and a depth of 2 mm in accordance with ISO 2818:2018. For the notched test pieces, in accordance with ISO179-1:2010, using a 1.0 J hammer, the broken test pieces were heated while sandwiched between glass plates on a hot stage set at 200 - 300 °C, and the carbon fiber [B] was uniformly dispersed in the molded product in a film form. The film with uniformly dispersed carbon fiber [B] was observed using an optical microscope (50 - 200 times magnification). The fiber lengths of 1000 randomly selected carbon fiber [B] were measured. Since the same carbon fiber was used in each example, the density and diameter of the carbon fiber were the same, and the weight average fiber length (L W ) was calculated from the following formula. Weight average fiber length = Σ(Mi 2 ×Ni) / Σ(Mi×Ni) Mi: Fiber length (mm) Ni: Number of fibers with fiber length Mi.

[0138] (2) Flexural modulus of the molded product For the ISO type dumbbell test pieces obtained from each example and comparative example, in accordance with ISO 178:2010, Amd.1:2013, using a three-point bending test jig (roller radius 5 mm), the fulcrum distance was set to 64 mm, and the flexural modulus was measured under the test conditions of a test speed of 2 mm / min. As the testing machine, an "Instron" (registered trademark) universal testing machine model 5566 (manufactured by Instron Corporation) was used.

[0139] (3) Vibration durability of the molded product For the test pieces with dimensions of 12.7 mm × 170 mm × 1 mm t obtained from each example and comparative example, in accordance with JIS G0602:1993 "Test method for vibration damping characteristics of vibration damping steel plates", the test was carried out by the one-end fixed impact method, and a free vibration waveform with the horizontal axis as time and the vertical axis as displacement was obtained. The logarithmic decrement was calculated from the obtained free vibration waveform using the above formula (1). For the period n, the logarithmic decrement was calculated at the 100th period.

[0140] (4) Acoustic performance evaluation The test pieces of 12.7 mm×170 mm×1 mmt obtained in each example and comparative example were attached to the upper surface of a cantilever beam made of SUS304 (15 mm×15 mm×0.5 mm thickness) with a double-sided tape using an acrylic adhesive. Then, the reverberation length was measured when the position 10 mm from the free-end side was struck with a metal bar made of SUS304 (φ5×200 mm) from a height of 30 mm. When the sound reverberated for 2 seconds or more, it was rated as A; when the sound reverberated for 1.5 seconds or more but less than 2 seconds, it was rated as B; when the sound reverberated for 1 second or more but less than 1.5 seconds, it was rated as C; and when the reverberation was less than 1 second, it was rated as D.

[0141] (5) Interfacial shear strength of thermoplastic resin [A] and carbon fiber [B] <First step> First, carbon fiber single filaments or carbon fiber bundles cut to a manageable length are prepared. In the case of fiber bundles, single filaments are extracted from the fiber bundles. The extracted single filaments are straightly attached to a fixing jig with an adhesive. After the adhesive is cured, the ends of the single filaments are cut so that the length of the single filaments protruding from both ends of the fixing jig becomes 20 mm, and a single filament with a fixing jig from which the single filaments protrude straightly from both ends is obtained. The single filaments attached to the fixing jig are observed using an optical microscope, and the lengths in the fiber diameter direction are measured at three points, and the average is taken as the fiber diameter df.

[0142] <Second step> The single filament with a fixing jig obtained in the first step is lowered from above the thermoplastic resin heated on a heater, and one end of the single filament is embedded in the resin. At this time, the embedding depth was controlled to about 300 μm using a micrometer. After the resin in which the single filament with a fixing jig was embedded was cooled to room temperature, the single filament was cut at a position 15 mm protruding from the resin, and a single filament embedding sample was obtained.

[0143] <Third step> The single filament embedding sample prepared in the second step was fixed to the stage of a vertical pull-out tester using an adhesive, and a pull-out test was performed at a speed of 1 μm / second. The maximum load value at that time was measured, and the interfacial shear strength τ was calculated by the following formula (2).

[0144] τ = F / (π·df·H) × 10 -6 ···(2) τ: Interfacial shear strength at the fiber / thermoplastic resin interface (MPa) F: Maximum load value (N) π: Pi df: Fiber diameter (μm) The embedding depth H (μm) was determined by the following equation (3) using the distance X (μm) from the bottom of the thermoplastic resin at the time of embedding to the tip of the single fiber and the height Y (μm) of the thermoplastic resin after the embedding was completed.

[0145] H = Y - X ···(3).

[0146] (6) Measurement of the tensile elastic modulus of carbon fiber The tensile elastic modulus of carbon fiber is determined according to the following procedure in accordance with the resin-impregnated strand test method of JIS R7608:2004. However, when the carbon fiber bundle has twists, it is untwisted by applying twists in the reverse direction equal to the number of twists before evaluation. As the resin formulation, "Celloxide (registered trademark)" 2021P (manufactured by Daicel Chemical Industries, Ltd.) / boron trifluoride monoethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) / acetone = 100 / 3 / 4 (parts by mass) is used, and as the curing conditions, normal pressure, a temperature of 125°C, and a time of 30 minutes are used. Ten strands of the carbon fiber bundle are measured, and the average value is taken as the strand elastic modulus. The strain range for calculating the strand elastic modulus is 0.1 to 0.6%.

[0147] (Reference Example 1) Preparation of carbon fiber [B-4] A spinning solution containing a polyacrylonitrile copolymer composed of acrylonitrile and itaconic acid was prepared. The spinning solution was once discharged into the air from a spinneret and then introduced into a coagulation bath composed of an aqueous solution of dimethyl sulfoxide by a dry-wet spinning method to obtain a coagulated yarn. After washing the obtained coagulated yarn with water, it was drawn in warm water at 90 °C at a bath draw ratio of 3, a silicone oil agent was applied, and drying was performed using a roller heated to a temperature of 160 °C. Furthermore, pressurized steam drawing was performed at a draw ratio of 4 to obtain a carbon fiber precursor fiber bundle with a single fiber fineness of 1.1 dtex. Next, the obtained precursor fiber bundles were combined into a single fiber number of 24,000, and heat treatment was performed in an oven at an air atmosphere of 230 to 280 °C with a draw ratio of 1.1 to convert them into flame-retardant fiber bundles. The obtained flame-retardant fiber bundles were subjected to a twisting treatment, and pre-carbonization treatment was performed at a draw ratio of 1.0 in a nitrogen atmosphere at a temperature of 300 to 800 °C to obtain pre-carbonized fiber bundles. Then, such pre-carbonized fiber bundles were subjected to carbonization treatment under the conditions of a draw ratio of 1.02 and a carbonization temperature of 1900 °C, and no sizing agent was applied to obtain carbon fiber bundles [B-4].

[0148] (Reference Example 2) Preparation of Fiber Bundle [H] On a roll heated to a coating temperature of 150 °C, a liquid film of the resin [D] shown in each Example and Comparative Example was formed by heating and melting. In order to form a film of a constant thickness on the roll, a reverse roll was used. The carbon fiber [B] bundles shown in each Example and Comparative Example were passed over this roll while being in contact with the roll to adhere the resin [D]. Next, in a chamber heated to an impregnation temperature of 250 °C under a nitrogen atmosphere, it was passed between five sets of roll presses with a diameter of 50 mm. By this operation, the resin [D] was impregnated into the inside of the carbon fiber bundle to form a fiber bundle [H].

[0149] (Reference Example 3) Preparation of Thermoplastic Resin Composition Using a JSW TEX-30α type twin-screw extruder (screw diameter 30 mm, die diameter 5 mm, barrel temperature 260 °C, screw rotation speed 150 rpm), the thermoplastic resin [A] and compound [C] shown in each example and comparative example were dry-blended to the composition ratios shown in each example and comparative example, and the resulting blend was fed from the main hopper. While degassing was carried out from the downstream vacuum vent, the molten resin composition was discharged from the die orifice. After cooling the obtained strands, they were cut with a cutter to obtain pellets of the thermoplastic resin composition.

[0150] The raw materials used in each example and comparative example are shown below.

[0151] Thermoplastic resin [A] [A-1] A polyarylene sulfide resin (manufactured by Toray Industries, Inc., PPS resin ““Torelina (registered trademark) M2888””) was used. [A-2] A polyamide resin (manufactured by Toray Industries, Inc., 6-nylon resin ““Amilan (registered trademark) CM1001””) was used. [A-3] A polyamide resin (manufactured by Toray Industries, Inc., 610-nylon resin ““Amilan (registered trademark) CM2001””) was used. [A-4] A polycarbonate resin (manufactured by Teijin Chemicals Ltd., aromatic polycarbonate resin ““Panlite (registered trademark) L-1225L””) was used.

[0152] Carbon fiber [B] [B-1] As carbon fiber [B-1], TORAYCA (registered trademark) T700S-24000-50E manufactured by Toray Industries, Inc. was used. Also, the value of the tensile modulus of carbon fiber [B-1] measured according to (6) above was 230 GPa, and the diameter was 7 μm.

[0153] [B-2] As carbon fiber [B-2], TORAYCA (registered trademark) M40J-12000-50E manufactured by Toray Industries, Inc. was used. Also, the value of the tensile modulus of carbon fiber [B-2] measured according to (6) above was 377 GPa, and the diameter was 5 μm.

[0154] [B-3] As the carbon fiber [B-3], TORAYCA (registered trademark) T800S-24000-10E manufactured by Toray Industries, Inc. was used. Also, the value of the tensile modulus of elasticity of the carbon fiber [B-3] measured according to the above (6) was 295 GPa, and the diameter was 5 μm.

[0155] [B-4] The carbon fiber produced in Reference Example 1 above was used. Also, the value of the tensile modulus of elasticity of the carbon fiber [B-4] measured according to the above (6) was 390 GPa. Also, the diameter of the obtained carbon fiber was 7 μm.

[0156] [B-5] As the carbon fiber [B-5], TORAYCA (registered trademark) T700S-24000-60E manufactured by Toray Industries, Inc. was used. Also, the value of the tensile modulus of elasticity of the carbon fiber [B-5] measured according to the above (6) was 230 GPa, and the diameter was 7 μm.

[0157] Compound [C] [C-1] As the aliphatic polycarbodiimide, "Carbodilite (registered trademark) HMV-8CA" manufactured by Nisshinbo Chemicals, Inc. was used.

[0158] Resin [D] [D-1] A solid bisphenol A type epoxy resin ("jER" (registered trademark) 1004AF manufactured by Mitsubishi Chemical Corporation) was used. [D-2] A terpene phenol resin ("Mighty Ace (registered trademark) YP-902" manufactured by Yasuhara Chemical Co., Ltd.) was used.

[0159] (Example 1) The resin composition containing [A-1] prepared according to Reference Example 3 was supplied from the main hopper of a TEX-30α type twin-screw extruder (screw diameter 30 mm, L / D = 32) and melt-kneaded. On the other hand, according to Reference Example 2, the fiber bundle [H] obtained by impregnating the carbon fiber [B-1] with the resin [D-1] was passed through a coating die for wire coating installed at the tip of the twin-screw extruder. The resin composition containing [A-1] was discharged into the coating die in a molten state and continuously arranged so as to coat the periphery of the fiber bundle [H]. At this time, the resin pressure measured by the resin pressure gauge attached to the melt-kneading apparatus was 1 MPa. Also, the discharge amount of the resin composition was adjusted so that the blending amounts of the various raw materials were as shown in Table 1 with respect to a total of 100 parts by weight of the thermoplastic resin [A], carbon fiber [B], and compound [C] at this time. After cooling the obtained continuous molding material, it was cut with a cutter to obtain a resin molding material in the form of 7-mm long fiber pellets.

[0160] The obtained long-fiber pellet-shaped molding material was injection-molded using a SE75DUZ-C250 type injection molding machine manufactured by Sumitomo Heavy Industries, Ltd. under the conditions of injection time: 2 seconds, back pressure: 10 MPa, holding pressure time: 10 seconds, cylinder temperature: 280 °C, and mold temperature: 90 °C to produce an ISO type dumbbell test piece (type A1 test piece specified in JIS K 7152-1:1999), a test piece of 12.7 mm × 170 mm × 1 mm thickness, and a test piece of 80 mm × 10 mm × 4 mm thickness. Here, the cylinder temperature indicates the temperature of the part of the injection molding machine that heats and melts the molding material, and the mold temperature indicates the temperature of the mold into which the molding material is injected to form a predetermined shape. The obtained test pieces were allowed to stand in a thermostatic and humidistatic chamber adjusted to a temperature of 23 °C and 50% RH for 24 hours and then evaluated by the above-described method. The evaluation results are shown in Table 1.

[0161] (Examples 2 and 3) Molded products were produced and evaluated in the same manner as in Example 1 except that the contents of [A] to [D] were changed as shown in Table 1. The evaluation results are shown in Table 1.

[0162] (Examples 4, 15, and 16) The molded product was produced and evaluated in the same manner as in Example 1, except that carbon fiber [B-1] was changed to carbon fiber [B-2] and the contents of components [A] to [D] were changed as described in Table 1. The evaluation results are shown in Table 1.

[0163] (Examples 5 and 6) The molded product was produced and evaluated in the same manner as in Example 1, except that carbon fiber [B-1] was changed to carbon fiber [B-3] and the contents of components [A] to [D] were changed as described in Table 1. The evaluation results are shown in Table 1.

[0164] (Examples 7 to 12, 17 and 18) The molded product was produced and evaluated in the same manner as in Example 1, except that carbon fiber [B-1] was changed to carbon fiber [B-4] and the contents of components [A] to [D] were changed as described in Tables 1 to 3. The evaluation results are shown in Tables 1 to 3.

[0165] (Example 13) The molded product was produced and evaluated in the same manner as in Example 1, except that thermoplastic resin [A-1] was changed to thermoplastic resin [A-2], carbon fiber [B-1] was changed to carbon fiber [B-3], and the contents of components [A] to [D] were changed as described in Table 2. The evaluation results are shown in Table 2.

[0166] (Example 14) The molded product was produced and evaluated in the same manner as in Example 1, except that thermoplastic resin [A-1] was changed to thermoplastic resin [A-2], carbon fiber [B-1] was changed to carbon fiber [B-4], and the contents of components [A] to [D] were changed as described in Table 2. The evaluation results are shown in Table 2.

[0167] (Example 19) The molded product was produced and evaluated in the same manner as in Example 1, except that thermoplastic resin [A-1] was changed to thermoplastic resin [A-3], carbon fiber [B-1] was changed to carbon fiber [B-4], resin [D-1] was changed to resin [D-2], and the contents of components [A] to [D] were changed as described in Table 3. The evaluation results are shown in Table 3.

[0168] (Example 20) A molded article was produced and evaluated in the same manner as in Example 1, except that the thermoplastic resin [A-1] was changed to the thermoplastic resin [A-4], the carbon fiber [B-1] was changed to the carbon fiber [B-4], and the contents of components [A] to [D] were changed as described in Table 3. The evaluation results are shown in Table 3.

[0169] (Comparative Examples 1 and 2) A molded article was produced and evaluated in the same manner as in Example 1, except that the contents of [A] to [D] were changed as described in Table 4. The evaluation results are shown in Table 4.

[0170] (Comparative Example 3) A molded article was produced and evaluated in the same manner as in Example 1, except that the carbon fiber [B-1] was changed to the carbon fiber [B-5], and the contents of components [A] to [D] were changed as described in Table 4. The evaluation results are shown in Table 4.

[0171] (Comparative Example 4) Using a TEX-30α type twin-screw extruder manufactured by JSW (screw diameter 30 mm, die diameter 5 mm, barrel temperature 320 °C, screw rotation speed 150 rpm), a dry blend of the thermoplastic resin [A-1], the carbon fiber [B-1], and the component [C-1] in the composition ratio shown in Table 4 was supplied from the main hopper, and melt-kneaded while degassing from the downstream vacuum vent. The molten resin composition was discharged from the die orifice, and the obtained strands were cooled and then cut with a cutter to obtain pellets of the thermoplastic resin composition.

[0172] The obtained pellet-shaped molding material was injection molded using a Sumitomo Heavy Industries, Ltd. SE75DUZ-C250 injection molding machine under the conditions of injection time: 2 seconds, back pressure: 10 MPa, holding pressure time: 10 seconds, cylinder temperature: 280 °C, and mold temperature: 90 °C to produce ISO type dumbbell test pieces (type A1 test pieces specified in JIS K 7152-1:1999), test pieces with dimensions of 12.7 mm × 170 mm × 1 mm thick, and test pieces with dimensions of 80 mm × 10 mm × 4 mm thick. Here, the cylinder temperature indicates the temperature of the part of the injection molding machine that heats and melts the molding material, and the mold temperature indicates the temperature of the mold into which the molding material is injected to form a predetermined shape. The obtained test pieces were left standing in a thermo-hygrostat chamber adjusted to a temperature of 23 °C and 50% RH for 24 hours and then evaluated by the aforementioned method. The evaluation results are shown in Table 4.

[0173] (Comparative Example 5) A molded product was produced and evaluated in the same manner as in Comparative Example 4, except that carbon fiber [B-1] was changed to carbon fiber [B-5] and the contents of components [A] to [D] were changed as described in Table 4. The evaluation results are shown in Table 4.

[0174] (Comparative Example 6) A molded product was produced and evaluated in the same manner as in Comparative Example 4, except that the contents of components [A] to [D] were changed as described in Table 4. The evaluation results are shown in Table 4.

[0175] (Comparative Example 7) A molded product was produced and evaluated in the same manner as in Example 1, except that thermoplastic resin [A-1] was changed to thermoplastic resin [A-2], carbon fiber [B-1] was changed to carbon fiber [B-5], and the contents of components [A] to [D] were changed as described in Table 4. The evaluation results are shown in Table 4.

[0176]

Table 1

[0177]

Table 2

[0178]

Table 3

[0179]

Table 4

[0180] Any of the molded products of Examples 1 to 12 and 15 to 18 showed excellent acoustic properties. When carbon fiber [B] with a higher tensile modulus was used, more excellent acoustic properties were shown. Also, Examples 13, 14, 19, and 20 showed excellent acoustic properties even when the thermoplastic resin was changed.

[0181] On the other hand, in Comparative Examples 1 and 2, since the content of carbon fiber [B] was small, the flexural modulus of the molded product was low, the logarithmic decrement was greater than 3, and the acoustic properties deteriorated. In Comparative Examples 3 and 7, since the interfacial shear strength between thermoplastic resin [A] and carbon fiber [B] was low, the logarithmic decrement increased and the acoustic properties deteriorated. In Comparative Examples 4 and 5, since a molded product was produced using a molding material obtained by melt-kneading, the weight-average fiber length (L w ) of the carbon fiber in the molded product was short, so the logarithmic decrement increased and the acoustic properties deteriorated. In Comparative Example 6, since the content of carbon fiber [B] was large, fiber breakage increased, and the weight-average fiber length (L w ) of carbon fiber [B] in the molded product became short, so the logarithmic decrement increased and the acoustic properties deteriorated.

Explanation of Signs

[0182] 1 Thermoplastic resin [A] 2 Carbon fiber [B] 3 Compound [C] 4 Resin [D] 5 Fiber bundle [H]

Claims

1. A fiber-reinforced thermoplastic resin molded article containing a thermoplastic resin [A] and carbon fibers [B], wherein, based on a total of 100 parts by weight of the thermoplastic resin [A] and the carbon fibers [B], the thermoplastic resin [A] is contained in an amount of 50 to 95 parts by weight and the carbon fibers [B] are contained in an amount of 5 to 50 parts by weight, and the weight-average fiber length (L ｗ ), is 0.5 to 10.0 mm, the tensile elastic modulus of the carbon fibers [B] is 250 GPa or more, the flexural elastic modulus of the molded article is 30 GPa or more, the interfacial shear strength between the thermoplastic resin [A] and the carbon fibers [B] is 15 MPa or more, and the logarithmic decrement of the molded article calculated by the following formula (1) is less than 2.5: A fiber-reinforced thermoplastic resin molded article: Logarithmic decrement δ = (1 / n) × ln(α （１） / α （１＋ｎ） ) Equation (1) δ: logarithmic decrement n: period (n = 100) α （１） : Maximum amplitude value α （１＋ｎ） : The amplitude value of the n-th cycle counted from the cycle having the maximum amplitude value.

2. The fiber-reinforced thermoplastic resin molded article according to claim 1, further containing a compound [C] having a reactive functional group, and containing 0.1 to 10 parts by weight of the compound [C] with respect to 100 parts by weight in total of the thermoplastic resin [A], the carbon fiber [B], and the compound [C].

3. The fiber-reinforced thermoplastic resin molded article according to claim 1 or 2, wherein the thermoplastic resin [A] is a resin containing a polyphenylene sulfide resin.

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