JP7323384B2 - Polyvinyl chloride-based carbon fiber reinforced composite material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a carbon fiber reinforced composite material in which a carbon fiber substrate is impregnated with a vinyl chloride resin composition.

Carbon fiber reinforced composite materials (hereinafter sometimes abbreviated as CFRP) composed of carbon fiber and matrix resin have high specific strength and specific modulus, excellent mechanical properties, and highly functional properties such as weather resistance and chemical resistance. have Therefore, CFRP is attracting attention in aircraft structural members, windmill blades, automobile outer panels, and general industrial applications, and its demand is increasing year by year.

As matrix resins, thermosetting resins typified by epoxy resins, which have low viscosity when impregnated with carbon fibers and have excellent adhesion to carbon fibers, have been conventionally known. In recent years, thermoplastic resins such as polyolefins and polyamide-based polymer alloys have been developed as matrix resins due to the demand for improved impact resistance, high productivity, and interest in recycling.

In order to take advantage of the excellent properties of carbon fibers, such as weight reduction and mechanical strength, it is important that the carbon fibers are uniformly dispersed in the matrix resin, and it is necessary that the resin viscosity during impregnation is low. . However, in general, thermoplastic resins tend to undergo thermal decomposition under high-temperature conditions, and many of them have high viscosity even in a molten state, which tends to cause problems such as insufficient resin impregnation.

On the other hand, in order to take advantage of the excellent mechanical properties of carbon fibers, it is also important that the interfacial adhesion between the carbon fibers and the matrix resin is excellent. For example, propylene-based resins have poor interfacial adhesion to carbon fibers, and it is difficult to obtain expected mechanical properties simply by melt-kneading propylene-based resins and carbon fibers. As a method to solve this problem, a modified propylene resin was developed in which maleic anhydride or the like was grafted onto a propylene resin, and by adding this, the interfacial adhesion between the propylene resin and the carbon fiber was improved. is planned.

By solving the above problems in terms of materials and processes, CFRP with a matrix resin such as polyolefin or polyamide-based polymer alloy has been put into practical use. In some cases, poor performance was a problem.

Vinyl chloride resin, which is a general-purpose thermoplastic resin, is excellent in flame retardancy, durability, oil resistance, and chemical resistance. Compared to ethylene-based resins and propylene-based resins, it has extremely low creep deformation and excellent mechanical strength. is known to be

However, vinyl chloride resin has a high melt viscosity among thermoplastic resins, and the processing temperature when impregnating vinyl chloride resin into carbon fiber is close to the thermal decomposition temperature of vinyl chloride resin, so it is difficult to impregnate carbon fiber. It is presumed that it accompanies this, and there is no example of its practical application. In fact, in Patent Literature 1, the amount of vinyl chloride resin is limited to that contained as an auxiliary component, and is only handled as a mixture with a thermosetting resin that dissolves vinyl chloride resin.

Since vinyl chloride resin is a polar polymer having chlorine groups, it is presumed to have better interfacial adhesiveness with carbon fibers than propylene resin, which is a non-polar polymer. However, vinyl chloride resin is prone to thermal decomposition and adhesion to molds during molding. In order to prevent adhesion to the metal surface, it is essential to add a lubricant or the like. Therefore, vinyl chloride resin generally has a higher additive content than other thermoplastic resins. As a result, the current situation is that it is not known how a high content of additives affects the interfacial adhesion between a vinyl chloride resin composition containing a large amount of additives and carbon fibers.

JP 2017-95537 A

As described above, the vinyl chloride resin composition has a high melt viscosity, a low thermal stability, and a high additive content. Therefore, it is presumed that the vinyl chloride-based resin composition is difficult to impregnate into the carbon fiber base material, making it difficult to form a composite. At present, there has not been sufficient investigation and clarification of what kind of vinyl chloride resin composition is suitable for producing CFRP. Therefore, there is still a demand for a vinyl chloride-based resin composition having good impregnating properties into carbon fiber substrates. Further, there is a demand for CFRP in which a carbon fiber base material is impregnated with such a vinyl chloride resin composition.

Means for Solving the Problems As a result of intensive studies, the inventors of the present invention have found that the above problems can be solved by using a vinyl chloride resin composition (A) that satisfies specific conditions. reached. That is, the gist of the present invention is as follows.

[1] A carbon fiber reinforced composite material comprising a vinyl chloride resin composition (A) and a carbon fiber base material (B),
The vinyl chloride resin composition (A) contains a vinyl chloride resin and at least one additive,
The vinyl chloride resin composition (A) has a complex viscosity η of 1<η<1500 at 200° C. and a frequency of 10 Hz,
The average degree of polymerization of the vinyl chloride resin is 400 or more and 1500 or less,
In the vinyl chloride resin composition (A), the content of the heat stabilizer is 0.1 to 30 parts by mass and the content of the internal lubricant is 20 parts by mass with respect to 100 parts by mass of the vinyl chloride resin. A carbon fiber reinforced composite material comprising:
[2] The carbon fiber reinforced composite material according to [1], wherein the vinyl chloride resin composition (A) has a complex viscosity η of 10<η<1000 at 200° C. and a frequency of 10 Hz.
[3] The thermal stabilizer is at least one selected from the group consisting of organotin stabilizers, lead stabilizers, calcium-zinc stabilizers, barium-zinc stabilizers, and barium-cadmium stabilizers. The carbon fiber reinforced composite material according to [1] or [2], which is a seed.
[4] The internal lubricant is at least one selected from the group consisting of butyl stearate, lauryl alcohol, stearyl alcohol, epoxy soybean oil, glycerin monostearate, stearic acid, and bisamide, [1]-[ 3], the carbon fiber reinforced composite material according to any one of the above items.
[5] The carbon fiber reinforcement according to any one of [1] to [4], wherein the external lubricant is at least one selected from the group consisting of paraffin wax, polyolefin wax, ester wax, and montanic acid wax. Composite material.
[6] In the vinyl chloride resin composition (A), the total content of the additives is 70 parts by mass or less with respect to 100 parts by mass of the vinyl chloride resin of [1] to [5]. The carbon fiber reinforced composite material according to any one of the above.
[7] Any one of [1] to [6], wherein the carbon fiber reinforced composite material has an average bending strength of 300 MPa or more in a three-point bending test when the fiber volume fraction (Vf) is 50±2%. of carbon fiber reinforced composites.
[8] A molded body made of the carbon fiber reinforced composite material according to any one of [1] to [7].

In the present invention, by using the vinyl chloride-based resin composition (A) that satisfies specific conditions, it is possible to obtain a CFRP that is excellent in impregnation into the carbon fiber substrate (B) and has good bending strength.

<Carbon fiber reinforced composite material>
A carbon fiber reinforced composite material according to the present invention is a carbon fiber reinforced composite material comprising a vinyl chloride resin composition (A) and a carbon fiber base material (B). Each element constituting the carbon fiber reinforced composite material will be described in detail below.

<Vinyl chloride resin composition (A)>
The vinyl chloride resin composition (A) preferably has excellent impregnating properties into the carbon fiber substrate (B). The vinyl chloride resin composition (A) has a complex viscosity η at 200° C. and a frequency of 10 Hz in the range of 1<η<1500, preferably 10<η<1000 Pa s, and 20<η< It is more preferably 800 Pa·s. When the complex viscosity η is less than 1500 Pa·s, the inside of the carbon fiber filament bundle can be impregnated with the resin, and the excellent mechanical properties of the carbon fiber can be utilized. On the other hand, when the complex viscosity η is more than 1 Pa·s, the mechanical strength of the matrix resin itself can be obtained to such an extent that the mechanical strength as CFRP is not impaired.

The vinyl chloride resin composition (A) should be excellent in interfacial adhesion to the surface of the carbon fiber substrate (B), that is, should have high compatibility.

The vinyl chloride resin used in the vinyl chloride resin composition (A) is not particularly limited, and in addition to homopolymers of vinyl chloride monomers, for example, (1) vinyl chloride monomer and vinyl chloride monomer and (2) a graft copolymer obtained by grafting a vinyl chloride monomer or a vinyl chloride resin to a polymer other than a vinyl chloride resin. Furthermore, chlorinated vinyl chloride resins obtained by chlorinating these vinyl chloride resins are also included. These vinyl chloride resins may be used alone, or two or more of them may be used in combination.

(1) Polymerizable monomers in copolymers of vinyl chloride monomers and polymerizable monomers other than vinyl chloride monomers are not particularly limited, but α-olefins having 2 to 16 carbon atoms ( ethylene, propylene, and butylene); vinyl esters of aliphatic carboxylic acids having 2 to 16 carbon atoms (e.g., vinyl acetate and vinyl propionate); alkyl vinyl ethers having 2 to 16 carbon atoms (e.g., butyl vinyl ether and cetyl vinyl ether); alkyl (meth)acrylates having 1 to 16 carbon atoms (e.g., methyl (meth)acrylate, ethyl (meth)acrylate and butyl acrylate); aryl (meth)acrylates (e.g., phenyl methacrylate); aromatic vinyl (e.g., styrene and α-substituted styrenes (e.g., α-methylstyrene)); vinyl halides (e.g., vinylidene chloride and vinylidene fluoride); and N-substituted maleimides (N-phenylmaleimide and N-cyclohexylmaleimide). mentioned.

(2) Polymers that give graft copolymers together with vinyl chloride monomers or vinyl chloride resins may be homopolymers or copolymers as long as they can be graft-polymerized with vinyl chloride monomers. things are also included. For example, copolymers of α-olefins and vinyl esters (e.g., ethylene-vinyl acetate copolymers); copolymers of α-olefins, vinyl esters, and carbon monoxide (e.g., ethylene-vinyl acetate-monoxide copolymers of α-olefins and alkyl (meth)acrylates (e.g., ethylene-methyl methacrylate copolymers and ethylene-ethyl acrylate copolymers); α-olefins and alkyl (meth)acrylates Copolymers with carbon monoxide (eg, ethylene-butyl acrylate-carbon monoxide copolymers); copolymers of two or more different α-olefins (eg, ethylene-propylene copolymers); unsaturated nitriles and dienes (eg, acrylonitrile-butadiene copolymers); polyurethanes; and chlorinated polyolefins (eg, chlorinated polyethylene and chlorinated polypropylene).

The vinyl chloride resin has an average degree of polymerization of 400 or more and 1500 or less, more preferably 400 or more and 800 or less. When the average degree of polymerization is at least the above lower limit, it is easy to obtain desirable physical properties (for example, toughness) from the vinyl chloride resin. When the average degree of polymerization is equal to or less than the above upper limit, the impregnating property into the carbon fiber base material (B) is improved.

(Additive)
Various additives added to the vinyl chloride resin composition (A) include heat stabilizers, lubricants, processing aids, impact modifiers, heat resistance improvers, antioxidants, ultraviolet absorbers, antistatic agents, light Stabilizers, fillers, pigments, flame retardants, plasticizers, and the like. Only one kind of the additive may be used, or two or more kinds thereof may be used in combination.

The total content of additives contained in the vinyl chloride resin composition (A) is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, with respect to 100 parts by mass of the vinyl chloride resin. It is preferably 50 parts by mass or less, and more preferably 50 parts by mass or less. A smaller amount can reduce the influence of exudation in the vicinity of the interface of the continuous carbon fiber substrate (B), and can suppress deterioration of physical properties such as bending strength of the carbon fiber reinforced composite material.

The heat stabilizer is not particularly limited, and includes heat stabilizers and heat stabilization aids. The heat stabilizer is not particularly limited, and examples thereof include organic tin stabilizers, lead stabilizers, calcium-zinc stabilizers, barium-zinc stabilizers, and barium-cadmium stabilizers.

The organotin stabilizers include dibutyltin mercapto, dioctyltin mercapto, dimethyltin mercapto, dibutyltin mercapto, dibutyltin maleate, dibutyltin maleate polymer, dioctyltin maleate, dioctyltin maleate polymer, dibutyltin laurate, and dibutyltin laurate polymer and the like. Only one of the above stabilizers may be used, or two or more thereof may be used in combination.

The heat stabilization aid is not particularly limited, and examples thereof include epoxidized soybean oil, phosphate ester, polyol, hydrotalcite, and zeolite. Only one type of the heat stabilization aid may be used, or two or more types may be used in combination.

The content of the heat stabilizer contained in the vinyl chloride resin composition (A) is 0.1 parts by mass or more and 30 parts by mass or less and 10 parts by mass or less with respect to 100 parts by mass of the vinyl chloride resin. is preferable, and it is more preferably 5 parts by mass or less. A smaller amount can reduce the influence of exudation in the vicinity of the interface of the continuous carbon fiber substrate (B), and can suppress deterioration of physical properties such as bending strength of the carbon fiber reinforced composite material.

Said lubricants include internal lubricants and external lubricants. The internal lubricant is used for the purpose of reducing the flow viscosity of the molten resin during molding and preventing frictional heat generation. The internal lubricant is not particularly limited, and includes butyl stearate, lauryl alcohol, stearyl alcohol, epoxy soybean oil, glycerin monostearate, stearic acid, bisamide, and the like. Only one type of the lubricant may be used, or two or more types may be used in combination.

The content of the internal lubricant contained in the vinyl chloride resin composition (A) is 20 parts by mass or less, preferably 10 parts by mass or less, and 5 parts by mass with respect to 100 parts by mass of the vinyl chloride resin. The following are more preferable. A smaller amount can reduce the influence of exudation in the vicinity of the interface of the continuous carbon fiber substrate (B), and can suppress deterioration of physical properties such as bending strength of the carbon fiber reinforced composite material.

The external lubricant is used for the purpose of enhancing the sliding effect between the molten resin and the metal surface during molding. The external lubricant is not particularly limited, and includes paraffin wax, polyolefin wax, ester wax, montanic acid wax, and the like. Only one type of the lubricant may be used, or two or more types may be used in combination.

The content of the external lubricant contained in the vinyl chloride resin composition (A) is 10 parts by mass or less, preferably 5 parts by mass or less, and 2 parts by mass with respect to 100 parts by mass of the vinyl chloride resin. The following are more preferable. A smaller amount can reduce the influence of exudation in the vicinity of the interface of the continuous carbon fiber substrate (B), and can suppress deterioration of physical properties such as bending strength of the carbon fiber reinforced composite material.

The processing aid is not particularly limited, and conventionally known processing aids can be used, and homopolymers or copolymers of alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and butyl methacrylate, alkyl methacrylates, and methyl Copolymers of alkyl acrylates such as acrylates, ethyl acrylate and butyl acrylate, copolymers of alkyl methacrylates with aromatic vinyl compounds such as styrene, α-methylstyrene and vinyltoluene, alkyl methacrylates, acrylonitrile and methacrylo Examples thereof include copolymers with vinyl cyanide compounds such as nitrile, and the like, and these can be used singly or in combination of two or more. Among these, alkyl acrylate-alkyl methacrylate copolymers having a weight average molecular weight of 100,000 to 2,000,000 can be preferably used. Specific examples include n-butyl acrylate-methyl methacrylate copolymer and 2-ethylhexyl acrylate-methyl methacrylate-butyl methacrylate copolymer. Only one type of the processing aid may be used, or two or more types may be used in combination.

The impact modifier is not particularly limited, and any conventionally known impact modifier can be used, including polybutadiene, polyisoprene, polychloroprene, chlorinated polyethylene, fluororubber, styrene- Butadiene copolymer rubber, methyl methacrylate-butadiene-styrene copolymer, methyl methacrylate-butadiene-styrene graft copolymer, acrylonitrile-styrene-butadiene copolymer rubber, acrylonitrile-styrene-butadiene graft Copolymer, styrene-butadiene-styrene block copolymer rubber, styrene-isoprene-styrene copolymer rubber, styrene-ethylene-butylene-styrene copolymer rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene Copolymer rubbers (EPDM), silicone-containing acrylic rubbers, silicone/acrylic composite rubber graft copolymers, silicone rubbers, and the like can be mentioned. Only one type of the impact modifier may be used, or two or more types may be used in combination.

The heat resistance improver is not particularly limited, and examples thereof include α-methylstyrene-based and N-phenylmaleimide-based resins. Only one type of the heat resistance improver may be used, or two or more types may be used in combination.

The antioxidant is not particularly limited, and phenolic antioxidants such as 4,4′-butylidenebis-(6-t-butyl-3-methylphenol), tris (mixed mono- and di-nonylphenyl) phosphite Phosphite antioxidants such as phyto, thioether antioxidants such as distearyl thiodipropionate, and the like. Among them, phenolic antioxidants such as 4,4'-butylidenebis-(6-t-butyl-3-methylphenol), which have a low high-temperature decomposition inhibiting function, are particularly preferred. Only one kind of the antioxidant may be used, or two or more kinds thereof may be used in combination.

The ultraviolet absorber is not particularly limited, and includes salicylic acid ester ultraviolet absorbers, benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, and cyanoacrylate ultraviolet absorbers. As for the said ultraviolet absorber, only 1 type may be used and 2 or more types may be used together.

The antistatic agent is not particularly limited, and conventionally known antistatic agents can be used, and anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, etc. are used. can do Examples of anionic surfactants include fatty acid salts, higher alcohol sulfates, liquid fatty oil sulfates, fatty amines, amide sulfates, dibasic fatty acid ester sulfone salts, fatty acid amide sulfonates, alkylaryl Sulfonates, formalin-condensed naphthalene sulfonates, mixtures thereof, and the like can be mentioned. Cationic surfactants include aliphatic amine salts, quaternary ammonium salts, alkylpyridium salts and mixtures thereof. Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol esters, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, mixtures thereof, and the like. be able to. A mixture of a nonionic surfactant and an anionic or cationic surfactant may also be used. Amphoteric surfactants include imidazoline type, higher alkylamino type (betaine type), sulfate ester, phosphate ester type, sulfonic acid type and the like. Only one antistatic agent may be used, or two or more antistatic agents may be used in combination.

The light stabilizer is not particularly limited, and includes hindered amine light stabilizers and the like. As for the said light stabilizer, only 1 type may be used and 2 or more types may be used together.

The filler is not particularly limited, and talc, heavy calcium carbonate, precipitated calcium carbonate, carbonates such as colloidal calcium carbonate, aluminum hydroxide, magnesium hydroxide, titanium oxide, clay, mica, wollastonite, zeolite. , silica, zinc oxide, magnesium oxide, carbon black, graphite, glass beads, glass fibers, carbon fibers, and metal fibers, as well as organic fibers such as polyamide. Only one kind of the filler may be used, or two or more kinds thereof may be used in combination.

The pigment is not particularly limited and includes organic pigments and inorganic pigments. Examples of the organic pigments include azo-based organic pigments, phthalocyanine-based organic pigments, threne-based organic pigments, and dye lake-based organic pigments. Examples of the inorganic pigments include oxide-based inorganic pigments, molybdenum chromate-based inorganic pigments, sulfide/selenide-based inorganic pigments, and ferrocyanine-based inorganic pigments. Only one type of the pigment may be used, or two or more types may be used in combination.

Examples of flame retardants include metal hydroxides, bromine compounds, triazine ring-containing compounds, zinc compounds, phosphorus compounds, halogen flame retardants, silicone flame retardants, intumescent flame retardants, antimony oxide, and the like. These can be used singly or in combination of two or more.

The plasticizer may be added for the purpose of enhancing workability during molding. The plasticizer is not particularly limited, and conventionally known plasticizers can be used. For example, phthalate ester plasticizers and non-phthalate plasticizers can be used. Phthalate plasticizers include dioctyl phthalate (DOP) and the like. Non-phthalate plasticizers include trimellitic acid-based compounds, phosphoric acid-based compounds, adipic acid-based compounds, citric acid-based compounds, ether-based compounds, polyester-based compounds, soybean oil-based compounds, and cyclohexanedicarboxylate. and terephthalic acid-based compounds. Only one type of the plasticizer may be used, or two or more types may be used in combination.

The content of the plasticizer contained in the vinyl chloride resin composition (A) is preferably as small as possible because a large amount of the plasticizer in the vinyl chloride resin composition (A) may impair the mechanical strength of CFRP. Specifically, the content of the plasticizer is 10 parts by mass or less, preferably 5 parts by mass or less, more preferably 1 part by mass or less, with respect to 100 parts by mass of the vinyl chloride resin. It is more preferably 0.1 part by mass or less, and most preferably does not contain the plasticizer.

For example, when an improvement in heat resistance and flame retardancy is expected, it is preferable to select a vinyl chloride resin containing a chlorinated vinyl chloride resin as a main component. In general, a chlorinated vinyl chloride resin composition has a higher melt viscosity than a vinyl chloride resin composition and is more likely to be thermally decomposed, making it difficult to impregnate carbon fibers. Therefore, in the case of using a chlorinated vinyl chloride resin for the vinyl chloride resin composition (A), by using a chlorinated vinyl chloride resin with a low degree of polymerization or by increasing the amount of additives added, the expected CFRP can be obtained that maintains heat resistance, flame retardancy, and mechanical properties.

<Carbon fiber base material (B)>
Definitions of carbon fibers and carbon fiber substrates in the present invention are shown below.
A carbon fiber is a fiber composed of a material containing carbon. It is a concept including the case of using together with other fibers and the case of using alone.
A carbon fiber base material is a carbon fiber fabric having carbon fiber bundles composed of a plurality of carbon fibers as a warp bundle and a weft bundle.
Carbon fiber is a concept including short carbon fiber, long carbon fiber, and continuous carbon fiber.
A short carbon fiber is a carbon fiber having a fiber length of 1 mm or less.
A long carbon fiber is a carbon fiber having a fiber length of 5 cm or less.
Continuous carbon fibers are carbon fibers other than short fibers and long fibers.

(Carbon fiber material)
The carbon fiber material is not particularly limited, and may be carbon fibers such as PAN (polyacrylonitrile)-based carbon fiber and pitch-based carbon fiber, and other fibers; metal fibers such as steel fibers; glass fibers, ceramic fibers, Inorganic fibers such as boron fibers; organic fibers such as aramid, polyester, polyethylene, nylon, vinylon, polyacetal, polyparaphenylene benzoxazole, and high-strength polypropylene; natural fibers such as kenaf and hemp, combined with multiple types may be From the viewpoint of the specific strength, it is preferable to consist only of carbon fibers.

Short carbon fibers, long carbon fibers, and continuous carbon fibers can be appropriately used as the carbon fibers used in the present invention, but continuous carbon fibers are preferable from the viewpoint of the mechanical properties of the obtained CFRP.

(Form and manufacturing method of carbon fiber base material (B))
The form of the fiber is not particularly limited as long as it is a continuous fiber, and for example, a form in which the tow is aligned in one direction and held by auxiliary weft yarns, a form in which the fiber is made into a woven fabric (cloth); A multi-axial warp knit in which a plurality of fiber sheets arranged in one direction are overlapped so that the directions of the fibers are different from each other and stitched with auxiliary yarns. A carbon fiber base material (B) can be obtained by producing carbon fibers by each production method based on the above-described configuration.

Each carbon fiber is generally a single fiber, and a plurality of carbon fibers are gathered to form a carbon fiber bundle. The number of carbon fibers constituting each carbon fiber bundle is preferably 1,000 to 50,000, more preferably 2,000 to 40,000, even more preferably 5,000 to 25,000.

The fiber diameter of the filaments is preferably 3 μm or more, and preferably 12 μm or less. If the fiber diameter is 3 μm or more, sufficient strength can be obtained, and for example, when the filament undergoes lateral movement on the surface of a roll or spool in various processing processes, it suppresses cutting and fuzz accumulation. can. The upper limit is usually about 12 μm for the reason that the carbon fiber can be easily produced.

Although the plurality of carbon fiber bundles is not particularly limited, it is preferable to form a sheet. The basis weight of the sheet-shaped carbon fiber bundle is, for example, preferably 100 g/m ² or more and 600 g/m ^{2 or} less, more preferably 150 g/m ² or more and 500 g/m ^{2 or} less. It is preferable that the basis weight is equal to or higher than the above lower limit in terms of efficiency when secondary processing is performed by laminating the obtained CFRP sheet, and if it is equal to or lower than the above upper limit, it is easy to obtain impregnation. is preferable.

As the carbon fiber base material (B), it is preferable to use a carbon fiber bundle that has undergone a fiber-opening treatment in advance (hereinafter sometimes referred to as a fiber-opened carbon fiber bundle) for the purpose of facilitating resin impregnation. The opening step is not particularly limited, and examples thereof include a method of including spacer particles, a method of squeezing the fibers with a round bar, a method of using an air current, and a method of vibrating the fibers with ultrasonic waves or the like. A preferred method is to include spacer particles. By increasing the inter-fiber distance in this way, even if high tension is applied to the carbon fibers in the manufacturing stage, the inter-fiber distance is widened in advance. , facilitates resin impregnation. Further, even if tension is applied to the fibers, the inter-fiber distance is less likely to narrow.

The spacer particles get between the carbon fibers in each fiber bundle, thereby opening the carbon fiber bundle. It is preferable that the spacer particles that have entered between the carbon fibers bridge the carbon fibers. Here, "crosslinked" means having a structure in which spacer particles interposed between carbon fibers are arranged so as to bridge at least two carbon fibers. Also, the spacer particles are preferably bonded to the carbon fibers via carbon allotropes present on the particle surfaces. The carbon fibers bridge between the carbon fibers, and the spacer particles adhere to the carbon fibers, thereby making it easier to more firmly maintain the open state of the fiber bundle.

The spacer particles are not particularly limited, but may contain, for example, a carbon allotrope. Examples of carbon allotropes in spacer particles include amorphous carbon, graphite, and diamond. Amorphous carbon includes amorphous carbon. Among these, amorphous carbon is preferred, and amorphous carbon is more preferred.

Here, the carbon allotrope is preferably derived from the carbon of the thermosetting resin, that is, the carbon allotrope is preferably obtained by carbonizing the thermosetting resin. Thermosetting resins include, for example, phenolic resins, epoxy resins, melamine resins, urea resins, unsaturated polyester resins, alkyd resins, polyurethanes, oxazine resins, and the like. Oxazine-based resins are preferable from the viewpoint of being able to form a film of. Examples of oxazine-based resins include benzoxazine resin and naphthoxazine resin. Among these resins, naphthoxazine resin is preferable because it is easily carbonized at a lower temperature, and is less likely to be excessively softened even under the conditions of temperature and pressure during CFRP production of the present invention. Therefore, the distance between the fibers is sufficiently secured, and the impregnating property of the resin is further enhanced.

Further, the spacer particles may be carbon allotrope particles composed of a carbon allotrope, or may be coated particles containing a core particle and a carbon allotrope coating the core particle. The spacer particles are preferably coated particles from the viewpoint of resin impregnation. The coated particles may be coated with the carbon allotrope over the entire surface, or may be partially coated with the carbon allotrope. The core particles can be used without any particular limitation as long as they are not deformed or destroyed by the pressure and temperature when the carbon fiber bundle is impregnated with the thermoplastic resin. For example, inorganic particles, organic particles, etc. can be used. can. As the core particles, inorganic particles or organic particles may be used alone, or both may be used in combination.

The average particle size of the spacer particles is preferably 1-20 μm. By using spacer particles having a size within this range, the spacer particles can be easily inserted between the carbon fibers, and the carbon fiber bundle can be spread more widely. The spacer particles preferably have an average particle size of 2 to 20 μm, particularly preferably 4 to 15 μm.

The total adhesion amount of spacer particles in the spread carbon fiber bundle is preferably 0.5 to 20% by mass, more preferably 1 to 10% by mass, based on the spread carbon fiber bundle. The carbon fiber bundle can be properly opened by setting the adhesion amount to be equal to or higher than the lower limit. Further, by setting the adhesion amount to the upper limit or less, it is possible to prevent the spread carbon fiber bundle from containing the spacer particles more than necessary and lowering the mechanical properties.

[Method for producing carbon fiber reinforced composite material]
The carbon fiber reinforced composite material according to the present invention can be produced, for example, by a method including (1) substrate preparation step and (2) resin impregnation step. Each step will be described in detail below.

(1) Substrate preparation step (1) Substrate preparation step is a step of preparing the carbon fiber substrate (B) described above. The carbon fiber substrate (B) is as described above, and for example, an appropriate carbon fiber material, form, and basis weight can be selected. Also, a woven fabric having a desired structure may be produced using commercially available carbon fiber bundles.

The step of preparing the carbon fiber substrate preferably includes a step of opening the carbon fiber bundle. The process of opening the carbon fiber bundle will be described below. Various methods are conceivable for opening the carbon fiber bundle, but as an example, the carbon fiber bundle may be provided with spacer particles arranged between the carbon fibers. By arranging the spacer particles between the carbon fibers, the carbon fiber bundles are opened, and the carbon fiber fabric can be sufficiently impregnated with the thermoplastic resin. In addition, when a treatment such as physical fiber opening is performed, the fiber bundle is horizontally opened, the pitch width of the fabric increases, and the design of the fiber-reinforced composite material may deteriorate. Since the carbon fiber fabric composed of carbon fiber bundles having spacer particles on the carbon fiber surface as described above is not physically opened, it is possible to suppress the deterioration of the design of the fiber reinforced composite material. and the carbon fiber bundles are sufficiently opened by the spacer particles, it is thought that the impregnability of the thermoplastic resin can be improved.

The spread carbon fiber bundle can be produced by contacting the carbon fiber bundle with the spread impregnation liquid and heating. After the carbon fiber bundle is spread, the carbon fiber fabric may be obtained using the spread carbon fiber bundle. Fiber is preferred.

As for the timing of contacting the carbon fiber bundle with the opening impregnation liquid, the carbon fiber bundle may be brought into contact with the opening impregnation liquid in advance before producing the carbon fiber fabric, or the carbon fiber bundle may be used as a warp bundle and a weft bundle. A carbon fiber fabric may be woven, and the resulting carbon fiber fabric may be brought into contact with an opening impregnation liquid to open a carbon fiber bundle.

The contact with the fiber-opening impregnation liquid may be performed by impregnating the carbon fiber bundle with the fiber-opening impregnation liquid. Specifically, the fiber-opening impregnation liquid may be sprayed or applied to the carbon fiber bundle, or the carbon fiber bundle may be immersed in the fiber-opening impregnation liquid. By bringing the carbon fiber bundle into contact with the fiber-opening impregnation liquid, the resin particles enter the gaps between the carbon fibers of the carbon fiber bundle, thereby opening the carbon fiber bundle.

The fiber-opening impregnation liquid used for fiber-opening the carbon fiber bundle contains a monomer capable of forming a thermosetting resin (hereinafter also simply referred to as "monomer"). A monomer becomes a thermosetting resin by reacting with it. As described above, the thermosetting resin is preferably an oxazine-based resin. When the thermosetting resin is an oxazine-based resin, the monomers are, for example, phenols, formaldehyde, and amines. The oxazine-based resin is preferably a naphthoxazine resin, as described above.

(2) Resin impregnation step (2) The resin impregnation step is a step of impregnating the vinyl chloride resin composition (A) into the carbon fiber substrate (B) prepared above. The carbon fiber reinforced composite material according to the present invention can be produced by impregnating the vinyl chloride resin composition (A) into the carbon fiber fabric composed of the above-described spread carbon fiber bundles.

For example, a film made of a vinyl chloride resin composition (A) is superimposed on a carbon fiber substrate (B) composed of an open carbon fiber bundle, and hot press molding is performed, or a The carbon fiber base material (B) can be impregnated with the vinyl chloride resin composition (A) by performing melt extrusion molding of the vinyl chloride resin composition (A). The carbon fiber reinforced composite material may be obtained by stacking a plurality of carbon fiber substrates (B) impregnated with the vinyl chloride resin composition (A), and at this time, the texture direction of each carbon fiber fabric is at a certain angle. By stacking the carbon fiber substrates (B) in a staggered manner, a carbon fiber reinforced composite material having even better mechanical strength can be obtained.

Extrusion molding or press molding can be used for hot pressing, and a carbon fiber reinforced composite material having a desired shape can be obtained by using a mold. The temperature at which the hot press molding is carried out can be carried out above the temperature at which the vinyl chloride resin composition (A) used softens or melts.

(bending strength)
The carbon fiber reinforced composite material according to the present invention has good bending strength. For example, when the fiber volume fraction (Vf) of the carbon fiber reinforced composite material is 50±2%, the bending strength in the three-point bending test is preferably 300 MPa or more, more preferably 400 MPa or more, and 500 MPa or more. It is even more preferable to have If the bending strength is at least the above lower limit, it can be suitably used in applications requiring high strength, such as aircraft structural members, windmill blades, and automobile outer panels. In addition, the three-point bending test conforms to JIS K 7074, and a test piece having a length (l) of 40 ± 1 mm, a width (b) of 15 ± 0.2 mm, and a thickness of h is measured. is a value (MPa) measured at 40 x hmm. In the bending test, a jig indenter with a radius of 5 mm and a width of 2 mm was used.

(Calculation of fiber volume fraction Vf)
The fiber volume fraction (Vf) of the carbon fiber reinforced composite material according to the present invention was calculated as follows.
Vf (%) = 100 x thickness of carbon fiber (mm)/thickness of carbon fiber reinforced composite material (mm)

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

<Resin film creation>
Vinyl chloride resin 1 (SL-P40 manufactured by Tokuyama Sekisui Kogyo Co., Ltd., degree of polymerization: about 400) was dissolved in tetrahydrofuran to a solution concentration of about 10%. Subsequently, 0.5 parts by mass of heat stabilizer 1 (methyltin mercapto, liquid stabilizer, manufactured by Nitto Kasei Co., Ltd.: AT5300) as an additive is added to the solution with respect to 100 parts by mass of the vinyl chloride resin, and sufficient The mixture was stirred to obtain a vinyl chloride resin composition (A). A solution of the vinyl chloride resin composition (A) thus obtained was applied onto a glass plate using a glass rod and allowed to stand still to volatilize the solvent to obtain a resin film. After peeling the obtained resin film from the glass plate, it was further dried in a circulating air oven at 60° C. for about 3 hours to obtain a resin film for CFRP production.

<Preparation of carbon fiber base material (B)>
A monomer consisting of 10 parts by mass of 1,5-dihydroxynaphthalene, 4 parts by mass of a 40% by mass aqueous methylamine solution, and 8 parts by mass of formalin (formaldehyde content: 37% by mass), and ethanol water as a solvent (ethanol content: 50% by mass) and 800 parts by mass were uniformly mixed to prepare a monomer solution in which the monomer was dissolved. Next, 10 parts by mass of particles composed of a divinylbenzene crosslinked polymer (manufactured by Sekisui Chemical Co., Ltd., trade name "Micropearl SP", average particle size 10 μm) were added to the above monomer solution to prepare an opening impregnation liquid. .

Subsequently, a carbon fiber fabric (number of carbon fibers: 3000, average diameter of carbon fibers: 7 μm, basis weight: 200 g/m ² , thickness: 0.19 mm, plain weave) composed of PAN-based carbon fiber bundles was prepared. The carbon fiber fabric was immersed in the fiber-opening impregnation liquid, pulled out, and then heated at 200° C. for 2 minutes. This heating caused a polymerization reaction and carbonization of the naphthoxazine resin, generated amorphous carbon derived from the naphthoxazine resin, and obtained a fabric of open carbon fiber bundles. The total attachment amount of organic particles and carbon allotrope in the spread carbon fiber bundle was 1% by mass. This spread carbon fiber bundle was used as a carbon fiber substrate (B).

(Example 1)
<Press molding of CFRP>
The carbon fiber base material (B) obtained above is sandwiched between the two resin films obtained above from the top and bottom, and the pressure is applied stepwise from 0 to 6 MPa at 200° C. for a total of about 10 minutes. CFRP was thus obtained. The obtained CFRP was used as a sample "Example-1" for evaluating physical properties.

(Example 2)
CFRP was obtained by the same process as in Example 1, except that the amount of heat stabilizer 1 was increased to 2 parts by mass in the preparation of the resin film. The obtained CFRP was used as a sample "Example-2" for evaluating physical properties.

(Example 3)
CFRP was obtained by the same process as in Example 1, except that the heat stabilizer 1 was increased to 10 parts by mass in the resin film preparation. The resulting CFRP was used as a sample "Example-3" for evaluating physical properties.

(Example 4)
CFRP was obtained by the same process as in Example 1, except that the heat stabilizer 1 was increased to 20 parts by mass in the resin film preparation. The obtained CFRP was used as a sample "Example-4" for evaluating physical properties.

(Example 5)
In the preparation of the resin film, the same process as in Example 1 was performed except that heat stabilizer 1 was changed to heat stabilizer 2 (octyl tin mercapto, liquid stabilizer, manufactured by Nitto Kasei Co., Ltd., KK6476) and 10 parts by mass were added. CFRP was obtained by The obtained CFRP was used as a sample "Example-5" for evaluating physical properties.

(Example 6)
CFRP was obtained by the same process as in Example 2 except that vinyl chloride resin 1 was changed to vinyl chloride resin 2 (manufactured by Tokuyama Sekisui Kogyo Co., Ltd., TS-640M, degree of polymerization: about 640). The obtained CFRP was used as a carbon fiber base material sample "Ex-6" for physical property evaluation.

(Example 7)
CFRP was obtained by the same process as in Example 2 except that 0.5 parts by mass of external lubricant 1 (HIWAX220RKT polyethylene wax manufactured by Mitsui Chemicals, Inc.) was added in the resin film preparation. The resulting CFRP was used as a carbon fiber base material sample "Ex-7" for evaluating physical properties.

(Example 8)
CFRP was obtained by the same process as in Example 2, except that 2 parts by mass of the external lubricant 1 was added in the resin film preparation. The obtained CFRP was used as a carbon fiber base material sample "Example-8" for physical property evaluation.

(Example 9)
CFRP was obtained by the same process as in Example 2, except that 5 parts by mass of the external lubricant 1 was added in the resin film preparation. The obtained CFRP was used as a carbon fiber base material sample "Ex-9" for physical property evaluation.

(Example 10)
CFRP was obtained by the same process as in Example 2, except that 5 parts by mass of external lubricant 2 (AC316 oxidized polyethylene wax manufactured by Honeywell) was added to the resin film. The resulting CFRP was used as a carbon fiber base material sample "Ex-10" for evaluating physical properties.

(Example 11)
CFRP was obtained by the same process as in Example 2 except that 5 parts by mass of external lubricant 3 (SG22 ester-based wax manufactured by Riken Vitamin Co., Ltd.) was added in the resin film preparation. The resulting CFRP was used as a carbon fiber base material sample "Ex-11" for evaluating physical properties.

(Example 12)
CFRP was obtained by the same process as in Example 2 except that 10 parts by mass of internal lubricant 1 (LOXIOL G60 glycerin monostearate manufactured by Emery Oleochemical Co., Ltd.) was added in the resin film preparation. The resulting CFRP was used as a carbon fiber base material sample "Ex-12" for evaluating physical properties.

(Example 13)
CFRP was obtained by the same process as in Example 2 except that 0.1 part by mass of plasticizer 1 (dioctyl phthalate manufactured by J-Plus Co., Ltd.) was added to the resin film. The resulting CFRP was used as a carbon fiber base material sample "Ex-13" for evaluating physical properties.

(Comparative example 1)
CFRP was obtained by the same process as in Example 2, except that 25 parts by mass of internal lubricant 1 was added in the resin film preparation. The resulting CFRP was used as a sample "ratio-1" for evaluating physical properties.

(Comparative example 2)
In the preparation of the resin film, vinyl chloride resin 3 (TS-1000R manufactured by Tokuyama Sekisui Kogyo Co., Ltd., degree of polymerization: about 1000 (high degree of polymerization product)) was used instead of vinyl chloride resin 1. CFRP was obtained by the process. The obtained CFRP was used as a carbon fiber base material sample "comparison-2" for evaluating physical properties.

(Comparative Example 3)
CFRP was obtained by the same process as in Example 1, except that 30 parts by mass of plasticizer 1 was added in the resin film preparation. The obtained CFRP was used as a sample "ratio-3" for evaluating physical properties.

<Preparation of sample for viscosity measurement>
The resin film made of the prepared vinyl chloride resin composition (A) was cut into a size of 30 (mm) × 90 (mm), weighed to be about 5 g, and heated at 170 ° C. for about 3 minutes. A sample for viscosity measurement with a thickness of 1 mm was prepared by press molding and cooling for about 1 minute.

<Measurement of complex viscosity η>
The complex viscosity η of the vinyl chloride resin composition (A) used for preparing the resin film was measured by the following method. Table 1 shows the measurement results.
A viscoelasticity measuring device (MCR102 manufactured by Anton Paar) was used for the measurement under the conditions of a parallel plate radius of 25 mm, a distance between parallel plates of 1 mm, a temperature of 200° C. and an angular frequency of 10 Hz to calculate the complex viscosity η.

<Bending strength measurement>
From the samples "actual-1" to "actual-5" and "ratio-1" to "ratio-4" prepared above, as a measurement sample conforming to JIS K 7074, length (l) 40 ± 1 mm, A test piece having a width (b) of 15±0.2 mm and a thickness of h was prepared with a distance between fulcrums (L) of 40×h (mm). The bending strength (MPa) of the prepared test piece was measured by a three-point bending method using a tester (AUTOGRAPH AGS-H manufactured by SHIMADZU). Table 1 shows the measurement results.

(Calculation of bending strength at Vf50%)
Measure the bending strength of a sample with Vf in the range of 50 ± 2% N = 3 or more, perform linear approximation from the measured value, calculate the bending strength at Vf 50%, and evaluate according to the following evaluation criteria. rice field. The evaluation results are shown in Table 1.
(Evaluation criteria)
400 MPa or more: ○
300 MPa or more and less than 400 MPa: △
Less than 300 MPa: ×

Claims (8)

A carbon fiber reinforced composite material comprising a vinyl chloride resin composition (A) and a carbon fiber base material (B),
The vinyl chloride resin composition (A) contains a vinyl chloride resin and at least one additive,
The vinyl chloride resin composition (A) has a complex viscosity η of 1<η<1500 at 200° C. and a frequency of 10 Hz,
The average degree of polymerization of the vinyl chloride resin is 400 or more and 1500 or less,
In the vinyl chloride resin composition (A), the content of the heat stabilizer is 0.1 to 30 parts by mass and the content of the internal lubricant is 20 parts by mass with respect to 100 parts by mass of the vinyl chloride resin. A carbon fiber reinforced composite material comprising: 2. The carbon fiber reinforced composite material according to claim 1, wherein the vinyl chloride resin composition (A) has a complex viscosity η of 10<η<1000 at 200° C. and a frequency of 10 Hz. The thermal stabilizer is at least one selected from the group consisting of organotin-based stabilizers, lead-based stabilizers, calcium-zinc-based stabilizers, barium-zinc-based stabilizers, and barium-cadmium-based stabilizers. , The carbon fiber reinforced composite material according to claim 1 or 2. Any one of claims 1 to 3, wherein the internal lubricant is at least one selected from the group consisting of butyl stearate, lauryl alcohol, stearyl alcohol, epoxy soybean oil, glycerin monostearate, stearic acid, and bisamide. The carbon fiber reinforced composite material according to item 1. The carbon fiber reinforced composite material according to any one of claims 1 to 4, wherein the external lubricant is at least one selected from the group consisting of paraffin wax, polyolefin wax, ester wax, and montanic acid wax. Claims 1 to 5, wherein the total content of the additives in the vinyl chloride resin composition (A) is 0.1 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the vinyl chloride resin. The carbon fiber reinforced composite material according to any one of . The carbon fiber according to any one of claims 1 to 6, wherein the carbon fiber reinforced composite material has an average bending strength of 300 MPa or more in a three-point bending test when the fiber volume fraction (Vf) is 50 ± 2%. Reinforced Composite. A molded body made of the carbon fiber reinforced composite material according to any one of claims 1 to 7.