Resin compositions, fiber materials, and molding materials

Abstract

To provide a resin composition from which a molding material excellent in adhesion and mechanical strength such as bending strength can be obtained, a fiber material, and a molding material.SOLUTION: A resin composition contains an epoxy resin, and a maleic anhydride-acrylic copolymer, where the epoxy equivalent of the epoxy resin is 150-300 g / eq. and the acid value of the maleic anhydride-acrylic copolymer is 100-500 mgKOH / g, and a content ratio (mass ratio) of the epoxy resin to the maleic anhydride-acrylic copolymer is 20 / 80 to 80 / 20.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition, a fiber material, and a molding material.

Background Art

[0002] Carbon fiber is lightweight and excellent in strength and modulus of elasticity. Therefore, as a composite material combined with various matrix resins, it is used in many fields such as aircraft members, spacecraft members, automobile members, ship members, civil engineering and construction materials, and sports goods.

[0003] As a typical form of a composite material using carbon fiber, there is a molded product obtained by press molding (a molding method of defoaming and shaping under pressure) a preform obtained by laminating prepregs. This prepreg is generally manufactured by impregnating a resin into a carbon fiber base material in which continuous carbon fibers are arranged in one direction.

[0004] On the other hand, although carbon fiber composite materials using discontinuous carbon fibers (chopped, web, etc.) that are excellent in shape followability to complex shapes and can be molded in a short time have been proposed, in terms of mechanical properties such as specific strength and specific rigidity and stability of properties, the practical performance as a structural material is superior to that of prepregs.

[0005] In recent years, as carbon fiber composite materials, molding materials excellent in molding properties, handling properties, and mechanical properties of the obtained molded products have been required. Furthermore, industrially, higher economic efficiency and productivity have become necessary. In order to meet these requirements, the development of prepregs using thermoplastic resins as matrix resins has been promoted.

[0006] To take advantage of the excellent properties of carbon fibers, it is important to improve the adhesion between the carbon fibers and the matrix resin. To improve the interfacial adhesion between the carbon fiber bundle and the matrix resin, methods such as gas-phase oxidation or liquid-phase oxidation are usually performed on the carbon fiber bundle to introduce oxygen-containing functional groups to the carbon fiber surface. For example, Patent Document 1 proposes a method to improve the interlaminar shear strength, which is an indicator of interfacial adhesion, by subjecting the carbon fiber bundle to electrolytic treatment.

[0007] Furthermore, if sufficient interfacial adhesion cannot be obtained by surface modification of the carbon fibers as described above, attempts are made to add sizing treatment. For example, Patent Documents 2 to 4 propose a method to improve interfacial adhesion by using a compound having an epoxy group as a sizing agent. In addition, Patent Documents 3 and 4 propose a method to improve the compatibility between carbon fibers coated with a sizing agent and the thermoplastic resin matrix resin by using a sizing agent having an amino group or amide group.

[0008] Furthermore, Patent Document 5 discloses that carbon fibers coated with a sizing agent, in which a layer of 10 nm or more exists in a cross section perpendicular to the longitudinal direction of the carbon fiber, in which the composition ratio of oxygen to all elements is 2% or more, and which has amino groups, amide groups, and more than three-functional epoxy groups, and which has a specific weight-average molecular weight, exhibit excellent adhesion to thermoplastic resins. However, even with the sizing agent coated carbon fibers, the adhesion (flexural strength in physical property evaluation) to polyamide resins, which exhibit excellent mechanical properties as thermoplastic resins, was not sufficient. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 04-361619 [Patent Document 2] Special Publication No. 63-14114 [Patent Document 3] Japanese Patent Publication No. 2013-166922 [Patent Document 4] Japanese Patent Publication No. 2006-89734 [Patent Document 5] Japanese Patent Publication No. 2019-65441 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] Therefore, the problem that the present invention aims to solve is to provide a resin composition, a fiber material, and a molding material that can be obtained that have excellent adhesive properties and excellent mechanical strength such as bending strength. [Means for solving the problem]

[0011] As a result of diligent research, the inventors have discovered that by using a resin composition containing an epoxy resin having a specific epoxy equivalent and a maleic anhydride-acrylic copolymer having a specific acid value, it is possible to obtain a molding material that can be used as a sizing agent for reinforcing fibers, exhibits excellent adhesion between the fibrous material obtained using the resin composition and thermoplastic resin, and has excellent mechanical strength such as flexural strength, thus completing the present invention.

[0012] In other words, the present invention relates to a resin composition containing an epoxy resin and a maleic anhydride-acrylic copolymer, wherein the epoxy equivalent of the epoxy resin is 150 to 300 g / eq, the acid value of the maleic anhydride-acrylic copolymer is 100 to 500 mg KOH / g, and the content ratio (mass ratio) of the epoxy resin and the maleic anhydride-acrylic copolymer is 20 / 80 to 80 / 20.

[0013] The present invention relates to the resin composition and a fibrous material containing reinforcing fibers.

[0014] In the present invention, it is preferable that the reinforcing fiber of the fibrous material is a carbon fiber.

[0015] The present invention relates to a molding material containing the aforementioned fiber material and a thermoplastic resin.

[0016] In the molding material of the present invention, it is preferable that the thermoplastic resin is a polyamide resin.

[0017] The molding material of the present invention preferably has a bending strength of 60 MPa or more. [Effects of the Invention]

[0018] By using the resin composition of the present invention as a sizing agent, the resulting fiber material (sized reinforced fiber) has excellent adhesion to the thermoplastic resin used as the matrix resin. As a result, the resulting molded material has excellent mechanical strength, such as bending strength, and can be used in fields requiring high mechanical strength, such as aircraft components, spacecraft components, and automotive components, making it very useful. [Modes for carrying out the invention]

[0019] [Epoxy resin] The resin composition of the present invention is a resin composition containing an epoxy resin and a maleic anhydride-acrylic copolymer, characterized in that the epoxy equivalent of the epoxy resin is 150 to 300 g / eq. Having an epoxy equivalent within the above range of epoxy resins results in high reactivity between the resin composition containing the epoxy resin as a sizing agent, the resulting fiber material (sized reinforcing fiber) containing reinforcing fibers, and the thermoplastic resin, such as a polyamide resin, described later, and the epoxy resin, improving adhesion and enabling the resulting molded material to exhibit excellent mechanical strength, making it useful.

[0020] Examples of the epoxy resin include an epoxy resin having a glycidyloxyaryl structure in the molecular structure obtained by glycidyl etherifying a polyhydric phenol compound or a phenol resin, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, etc., which are bisphenol type epoxy resins; cresol novolak type epoxy resins such as orthocresol novolak type epoxy resin, phenol novolak type epoxy resin, naphthol novolak type epoxy resin, bisphenol A novolak type epoxy resin, brominated phenol novolak type epoxy resin, alkylphenol novolak type epoxy resin, bisphenol S novolak type epoxy resin, alkoxy group-containing novolak type epoxy resin, brominated phenol novolak type epoxy resin, etc., which are novolak type epoxy resins; other difunctional epoxy resins such as phenol aralkyl type epoxy resin (epoxidized product of general name zylock resin), diglycidyl ether of resorcin, diglycidyl ether of hydroquinone, diglycidyl ether of catechol, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, sulfur-containing epoxy resin, stilbene type epoxy resin, etc., triglycidyl isocyanurate, triphenylmethane type epoxy resin, tetraphenyl ethane type epoxy resin, dicyclopentadiene-phenol addition reaction type epoxy resin, biphenyl-modified novolak type epoxy resin (epoxidized product of polyhydric phenol resin in which phenol nuclei are linked by bismethylene groups), alkoxy group-containing novolak type epoxy resin, alkoxy group-containing phenol aralkyl resin, tetrabromobisphenol A type epoxy resin, brominated phenol novolak type epoxy resin, etc. Among them, from the viewpoint of imparting heat resistance, phenol novolak type epoxy resin, cresol bonolak type epoxy resin, etc. are preferable. These may be used alone or in combination of two or more kinds.

[0021] The epoxy equivalent of the epoxy resin is 150 to 300 g / eq, preferably 160 to 280 g / eq, and more preferably 170 to 250 g / eq. When the epoxy equivalent is within the above range, the adhesion between the fiber material and the thermoplastic resin is good, which is preferable.

[0022] [Maleic anhydride·acrylic copolymer] The resin composition of the present invention is a resin composition containing an epoxy resin and a maleic anhydride·acrylic copolymer, and is characterized in that the acid value of the maleic anhydride·acrylic copolymer is 100 to 500 mgKOH / g. The maleic anhydride·acrylic copolymer (hereinafter, may be simply referred to as "copolymer") has a function as a curing agent (crosslinking agent) with respect to the epoxy resin, and further, the resin composition containing the copolymer as a sizing agent and a fiber material (sized reinforcing fiber) that may contain a reinforcing fiber, and the adhesion between the resin composition and a polyamide resin or the like which is a thermoplastic resin described later is improved, and the obtained molding material can exhibit excellent mechanical strength and is useful.

[0023] As the maleic anhydride·acrylic copolymer, maleic anhydride which is an unsaturated carboxylic acid is used. By using the maleic anhydride, the reactivity between a polyamide resin or the like which is a thermoplastic resin described later and the resin composition containing the copolymer is high, the adhesion is improved, and it is useful.

[0024] Furthermore, in the synthesis of the maleic anhydride-acrylic copolymer, in addition to maleic anhydride, usable acrylic monomers include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, ( (Meth)acrylic acid esters such as 2-hydroxybutyl meth)acrylate, benzyl (meth)acrylate, glycidyl (meth)acrylate, (meth)acrylic acid, (di)ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glyceryl di(meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and acrylamide can be used. In particular, (meth)acrylic monomers having linear or branched alkyl groups with 1 to 12 carbon atoms are preferred from the viewpoint of viscosity reduction, heat resistance of the resulting molded material, and adhesion between the fiber material and the thermoplastic resin, for example methyl (meth)acrylate, butyl (meth)acrylate, and lauryl (meth)acrylate. From the viewpoint of improving the wettability (fiber wettability) of the maleic anhydride-acrylic copolymer to the reinforcing fibers, (meth)acrylic monomers having linear or branched alkyl groups with 4 to 12 carbon atoms are more preferred, for example butyl (meth)acrylate and lauryl (meth)acrylate. These may be used alone or in combination of two or more.

[0025] The content ratio (mass ratio) of maleic anhydride and acrylic monomer constituting the maleic anhydride-acrylic copolymer is preferably 25 / 75 to 75 / 25, and more preferably 30 / 70 to 70 / 30, from the viewpoint of adhesion between the fiber material and the thermoplastic resin.

[0026] In addition to the maleic anhydride and acrylic monomers that constitute the maleic anhydride-acrylic copolymer, polymerizable monomers containing unsaturated double bonds, such as styrene, can be used as other monomer components as needed.

[0027] Regarding the content ratio of maleic anhydride and acrylic monomer constituting the maleic anhydride-acrylic copolymer, from the viewpoint of improving wettability to reinforcing fibers (fiber wettability), 70 to 100% by mass is preferred, and 80 to 100% by mass is more preferred, based on 100% by mass of the total amount of monomer components.

[0028] The maleic anhydride-acrylic copolymer can be obtained by polymerizing maleic anhydride, acrylic monomers, etc., in combination as appropriate according to the desired properties. Furthermore, the maleic anhydride-acrylic copolymer may include random copolymers, block copolymers, graft copolymers, etc.

[0029] (Polymerization method) Any suitable method can be used to polymerize the maleic anhydride-acrylic copolymer, including, for example, solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerization methods. Among these, solution polymerization is preferred from the viewpoint of ease of handling.

[0030] (Radical polymerization initiator) The maleic anhydride-acrylic copolymer may contain a radical polymerization initiator, for example, when undergoing radical polymerization. The radical polymerization initiator may be, for example, a thermal polymerization initiator that generates free radicals when heated. These may be used individually or in combination of two or more.

[0031] Examples of the radical polymerization initiators include peroxide-based radical polymerization initiators and azo-based radical polymerization initiators. Among these, peroxide-based radical polymerization initiators are preferred.

[0032] Examples of the peroxide-based radical polymerization initiators include: hydroperoxide compounds such as 1,1,3,3-tetramethylbutyl hydroperoxide; dialkylperoxide compounds such as tert-butylcumyl peroxide, di-tert-butyl peroxide, di-tert-hexyl peroxide, dicumyl peroxide, 1,4-bis(1-tert-butylperoxy-1-methylethyl)benzene, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; diacyl peroxide compounds such as dilauroyl peroxide, didecanoyl peroxide, dicyclohexyl peroxydicarbonate, and bis(4-tert-butylcyclohexyl) peroxydicarbonate; and tert-butylperoxydicarbonate. Examples include peroxyester compounds such as oxyacetate, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxy-2-ethylhexanoate, tert-hexyl peroxy-2-ethylhexanoate, tert-butyl peroxyneodecanoate, tert-hexyl peroxyisopropyl monocarbonate, tert-butyl peroxylaurate, (1,1-dimethylpropyl)2-ethyl perhexanoate, tert-butyl 2-ethyl perhexanoate, tert-butyl 3,5,5-trimethyl perhexanoate, tert-butyl peroxy-2-ethylhexyl monocarbonate, and tert-butyl peroxymaleic acid.

[0033] Examples of the azo radical polymerization initiators include azonitrile compounds such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitride), 1-[(1-cyano-1-methylethyl)azo]formamide, and 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile; 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide], and 2,2'-azobis[2-methyl-N-[1,1-bis(hydroxymethyl) Examples include azoamide compounds such as [(2-methyl)ethyl]propionamide], 2,2'-azobis[2-methyl-N-[2-(1-hydroxybutyl)]-propionamide], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)-propionamide], 2,2'-azobis(2-methylpropionamide) dihydrate, 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2'-azobis(N-butyl-2-methylpropionamide), and 2,2'-azobis(N-cyclohexyl-2-methylpropionamide); and alkylazo compounds such as 2,2'-azobis(2,4,4-trimethylpentane) and 2,2'-azobis(2-methylpropane).

[0034] Examples of commercially available radical polymerization initiators include NOF Corporation's "Perbutyl C," "Perbutyl A," "Perbutyl P," "Perbutyl L," "Perbutyl O," "Perbutyl ND," "Perbutyl Z," "Perbutyl I," "Permil P," "Permil D," "Perhexyl D," "Perhexyl A," "Perhexyl I," "Perhexyl Z," "Perhexyl ND," "Perhexyl O," "Perhexyl PV," and "Perhexyl O."

[0035] The amount of polymerization initiator used can be any amount used in the usual manner. For example, it can be selected from a range of about 0.005 to 1 part by mass per 100 parts by mass of the total amount of monomers constituting the maleic anhydride-acrylic copolymer, and preferably 0.01 to 0.8 parts by mass.

[0036] The polymerization temperature and polymerization time can be appropriately selected depending on the type of monomer used, the type of polymerization initiator, etc. For example, the polymerization temperature can be set to about 20 to 150°C, and the polymerization time can be set to about 2 to 240 hours.

[0037] (Chain transfer agent) Furthermore, various conventionally known chain transfer agents (molecular weight modifiers or degree of polymerization modifiers) can be used for polymerization as needed. Examples of such chain transfer agents include mercaptans such as n-lauryl mercaptan, t-lauryl mercaptan, glycidyl mercaptan, and 2-mercaptoethanol, with t-lauryl mercaptan being preferred. These may be used individually or in combination of two or more.

[0038] The amount of the chain transfer agent used can be any amount that is used normally. For example, it can be about 0.001 to 0.5 parts by mass, preferably about 0.02 to 0.15 parts by mass, based on 100 parts by mass of the total amount of monomers constituting the maleic anhydride-acrylic copolymer.

[0039] The acid value of the maleic anhydride-acrylic copolymer is 100 to 500 mg KOH / g, preferably 150 to 480 mg KOH / g, and more preferably 250 to 460 mg KOH / g. When the pre-acid value is within the above range, polymerization is facilitated and useful.

[0040] [Resin composition] The resin composition of the present invention is characterized in that the content ratio (mass ratio) of the epoxy resin and the maleic anhydride-acrylic copolymer is 20 / 80 to 80 / 20. Having the content ratio (mass ratio) within the above range is preferable because it results in good adhesion between the fiber material and the thermoplastic resin. The mass ratio of the epoxy resin and the maleic anhydride-acrylic copolymer is preferably 25 / 75 to 75 / 25, more preferably 30 / 70 to 70 / 30, and even more preferably 35 / 65 to 65 / 35.

[0041] (Hardening agent (crosslinking agent)) In addition to the epoxy resin and the maleic anhydride-acrylic copolymer, the resin composition may further contain a curing agent (crosslinking agent) as needed. The crosslinking agent is not particularly limited, but examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, metal chelate-based crosslinking agents, carbodiimide-based crosslinking agents, etc. The crosslinking agent can be used as appropriate depending on the type of functional group contained in the resin composition used. These may be used alone or in combination of two or more.

[0042] A curing catalyst can be used in the resin composition from the viewpoint of promoting the curing reaction. Examples of curing catalysts include amines such as triethylamine, N,N-benzylmethylamine, N,N-dimethylphenylamine, and N,N-dimethylaniline; imidazoles such as methylimidazole, 1,2-dimethylimidazole, and 2-methyl-4-methylimidazole; and phosphines such as triphenylphosphine and tributylphosphine.

[0043] (Other additives) The resin composition may optionally contain other additives. Examples of such additives include silane coupling agents, lubricants, fillers, thixotropic agents, tackifiers, waxes, heat stabilizers, light stabilizers, fluorescent whitening agents, foaming agents, pH adjusters, leveling agents, gelation inhibitors, dispersion stabilizers, antioxidants, radical scavengers, heat resistance modifiers, inorganic fillers, organic fillers, plasticizers, reinforcing agents, catalysts, antibacterial agents, antifungal agents, rust inhibitors, thermoplastic resins, thermosetting resins, pigments, dyes, conductivity modifiers, antistatic agents, moisture permeability enhancers, water repellents, oil repellents, hollow foams, water-containing compounds, flame retardants, water absorbents, moisture absorbents, deodorants, foam stabilizers, defoamers, antifungal agents, preservatives, antialgal agents, pigment dispersants, blocking inhibitors, and hydrolysis inhibitors. The amounts of these additives are not particularly limited and can be selected as appropriate.

[0044] (solvent) The resin composition may contain a solvent as needed. Examples of the solvent include acetone, diethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, tetrahydrofuran, dioxane, ethyl acetate, butyl acetate, propyl acetate, n-pentane, n-hexane, cyclohexane, n-heptane, benzene, toluene, xylene, carbon tetrachloride, dichloromethane, chloroform, trichloroethane, dimethylformamide, N-methylpyrrolidone, acetonitrile, and the like. Within the range of the above usage amount, it is effective in reducing viscosity, makes it easy to apply and impregnate the reinforcing fibers with the resin composition (varnish), and is preferable due to its excellent workability.

[0045] The resin composition can form cured products such as films hardened by a crosslinking reaction between the epoxy resin and the maleic anhydride-acrylic copolymer. Specifically, by applying and impregnating reinforcing fibers with the resin composition, which is a mixture of the epoxy resin and the maleic anhydride-acrylic copolymer, and then heating, the epoxy resin contained in the resin composition reacts with the maleic anhydride-acrylic copolymer to form cured products such as films. The resulting fiber material and the molding material obtained using the fiber material can exhibit excellent adhesion and bundling properties.

[0046] [Textile materials] The fibrous material of the present invention is characterized by containing the resin composition and reinforcing fibers. By using the resin composition and the reinforcing fibers, a cured product such as a film can be formed on the surface of the reinforcing fibers. Furthermore, by coating and impregnating with a thermoplastic resin such as a polyamide resin, the adhesion between these materials is excellent, and the resulting molded material has excellent mechanical strength, such as bending strength, which is preferable.

[0047] (Reinforced fiber) Examples of the reinforcing fibers include carbon fibers, glass fibers, silicon carbide fibers, alumina fibers, boron fibers, metal fibers, aramid fibers, vinylon fibers, and tetron fibers, but carbon fibers or glass fibers are preferred, and carbon fibers are more preferred, as they yield molded products with higher strength and elasticity. These reinforcing fibers can be used individually or in combination of two or more types.

[0048] As the aforementioned glass fibers, for example, those obtained from alkali-containing glass, low-alkali glass, alkali-free glass, etc., can be used, but it is preferable to use alkali-free glass (E glass), which has less deterioration over time and stable mechanical properties.

[0049] Various types of carbon fibers can be used, such as polyacrylonitrile-based, pitch-based, and rayon-based fibers. Among these, polyacrylonitrile-based fibers are preferred because they allow for easy acquisition of high-strength carbon fibers.

[0050] As the reinforcing fibers, for example, those that have been twisted, spun, processed into spinning, or nonwoven can be used. Furthermore, as the carbon fibers, the following forms can be used: filaments, yarns, rovings, strands, chopped strands, felts, needle-punched materials, cloths, roving cloths, milled fibers, nanofibers, and the like.

[0051] A method for forming a fibrous material by forming a film on the surface of the reinforcing fibers using the resin composition includes, for example, a method in which the resin composition is uniformly applied to the surface of the reinforcing fibers by a known method such as a kiss coater, roller, impregnation, spray, or brush, and then cured at room temperature or under heating. If the resin composition contains an organic solvent as a solvent, it is preferable to heat-dry it after application using a heating roller, hot air, or hot plate.

[0052] Furthermore, when the curing is performed, for example, to form a cured film by a crosslinking reaction of the resin composition, it is preferable to heat to approximately 200-300°C, more preferably 250-290°C, and even more preferably 260-280°C from the viewpoint of excellent mechanical properties (flexural strength) of the molded material.

[0053] The content of the reinforcing fibers in the components of the fiber material of the present invention is preferably in the range of 1 to 40% by mass, and more preferably in the range of 3 to 20% by mass, since this further improves the mechanical strength of the resulting molded material.

[0054] [Molding material] The molding material of the present invention is characterized by containing the fiber material and a thermoplastic resin. When the fiber material (sized reinforced fiber) surface-treated with the resin composition is used in combination with a thermoplastic resin, which is a matrix resin, to form a molding material, the adhesion (tightness) of the interface between the fiber material and the thermoplastic resin can be significantly improved, thereby improving the mechanical strength, such as the bending strength, of the molding material.

[0055] (thermoplastic resin) Examples of thermoplastic resins that can be used include polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyolefin resins such as polypropylene, polystyrene, polycarbonate, polyphenylene sulfide, and polyphenylene oxide, polyamide resins such as nylon 6 and nylon 6,6, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, and polyacetal. Among these, polyamide resins are preferred from the viewpoint of the mechanical properties of the molded product.

[0056] Examples of molding materials comprising the surface-treated fiber material (sized reinforced fiber) and the thermoplastic resin (and polymerizable monomers, etc., as needed) include prepregs and sheet molding compounds (SMC).

[0057] As an example of the prepreg, one method involves applying the thermoplastic resin onto a release paper, placing a surface-treated fiber material on the applied surface, and pressing and impregnating it using a roller or the like as needed.

[0058] Furthermore, the sheet molding compound can be manufactured, for example, by thoroughly impregnating the surface-treated fiber material with the thermoplastic resin and processing it into a sheet.

[0059] The curing of the molding material can be advanced, for example, by radical polymerization under pressure (e.g., 1-5 MPa) or atmospheric pressure, heating (e.g., 200-300°C), or light irradiation. In such cases, known thermosetting agents, photocuring agents, etc., can be used in combination.

[0060] [Application] The resin composition of the present invention has excellent adhesive and fiber bundling properties, and yields a high-strength molding material. Therefore, it can be used in a wide range of applications, including coatings, adhesives, molding materials, reinforcing fiber bundling agents (sizing agents), paper processing agents, cement admixtures, sealants, waterproofing agents, and other building materials, as well as aircraft components, spacecraft components, automobile components, ship components, civil engineering and construction materials, and sporting goods. [Examples]

[0061] The present invention will be described in more detail below with reference to examples, but the present invention shall not be construed as being limited to the following examples unless it exceeds the gist of the invention.

[0062] (Measurement of acid value) Based on the amount used, the theoretical acid value of the resulting copolymer was calculated using the following formula. In the formula below, "acid-functional group-containing monomer" refers to maleic anhydride or other acid-functional group-containing monomers (e.g., acrylic acid). Theoretical acid value of copolymer (mgKOH / g) = [(Mass of acid-functional group-containing monomer / Mass of total monomers) × 100 / Molecular weight of acid-functional group-containing monomer] × Number of functional groups in acid-functional group-containing monomer × 561

[0063] (Viscosity measurement) Measurements (mPa·s) were taken using a Type B viscometer under the conditions of rotor No. 3 or No. 4 and a rotation speed of 60 rpm. Furthermore, from the viewpoint of workability and wettability to fibers (fiber wettability), a viscosity of 1 to 10,000 mPa·s is preferred, and 1,000 to 50,000 mPa·s is more preferred.

[0064] [Synthesis Example 1] (Preparation of maleic anhydride-acrylic copolymer) In a 2.0 L reaction vessel equipped with a stirrer, thermometer, condenser, and nitrogen blower, 98.4 parts by mass of maleic anhydride and 200.0 parts by mass of methyl isobutyl ketone were charged and heated to 120°C. Then, 147.6 parts by mass of methyl acrylate, 1.0 part by mass of polymerization initiator (Perhexyl O, manufactured by NOF Corporation, t-hexylperoxy-2-ethylhexanoate), and 50.0 parts by mass of methyl isobutyl ketone were added dropwise over 3 hours. After holding for 2 hours following the dropwise addition, the mixture was cooled to obtain a maleic anhydride-acrylic copolymer with a theoretical acid value of approximately 460. The copolymer content in the solution containing the obtained copolymer (hereinafter referred to as "non-volatile content of the copolymer") was 49.5% by mass, and the viscosity was 1900 mPa·s.

[0065] [Synthesis Example 2] (Preparation of maleic anhydride-acrylic copolymer) In a 2.0 L reaction vessel equipped with a stirrer, thermometer, condenser, and nitrogen blower, 98.4 parts by mass of maleic anhydride and 200.0 parts by mass of methyl isobutyl ketone were charged and heated to 80°C. Then, 140.2 parts by mass of butyl methacrylate, 4.9 parts by mass of methacrylic acid, 2.5 parts of styrene, 1.0 part by mass of polymerization initiator (Perhexyl O, manufactured by NOF Corporation, t-hexylperoxy-2-ethylhexanoate), and 50.0 parts by mass of methyl isobutyl ketone were added dropwise over 3 hours. After holding for 2 hours following the dropwise addition, the mixture was cooled to obtain a maleic anhydride-acrylic copolymer with a theoretical acid value of approximately 460. The non-volatile content of the copolymer was 50.3% by mass, and the viscosity was 4950 mPa·s.

[0066] [Synthesis Example 3] (Preparation of acrylic acid and acrylic copolymers) In a 2.0 L reaction vessel equipped with a stirrer, thermometer, condenser, and nitrogen blower, 200.0 parts by mass of methyl isobutyl ketone were charged and heated to 120°C. Then, 145.0 parts by mass of acrylic acid, 101.0 parts by mass of methyl acrylate, 1.0 part by mass of polymerization initiator (Perhexyl O, manufactured by NOF Corporation, t-hexylperoxy-2-ethylhexanoate), and 50.0 parts by mass of methyl isobutyl ketone were added dropwise over 3 hours. After holding for 2 hours following the dropwise addition, the mixture was cooled to obtain an acrylic acid-acrylic copolymer with a theoretical acid value of approximately 460. The non-volatile content of the copolymer was 49.7% by mass, and the viscosity was 1150 mPa·s.

[0067] [Example 1] (Preparation of fiber materials) A resin composition was prepared by mixing and dissolving 75.0 parts by mass of the copolymer obtained in Synthesis Example 1, 25.0 parts by mass of phenol novolac type epoxy resin (Epiclon N-770, manufactured by DIC Corporation, epoxy equivalent 180-200 g / eq), and 1900.0 parts by mass of methyl ethyl ketone. Next, a 170mm x 170mm test cloth weighing approximately 6g was dipped in 20g of the resin composition per cloth. After processing, the cloth was dried in a fume hood to evaporate the solvent. After evaporation, the obtained test cloth was sandwiched between a Teflon woven sheet (EBM, product name: Thick Baking Sheet, thickness 0.1mm) and a 2mm thick stainless steel metal plate, and heated in a hot press set to 270°C under a pressure of 2MPa for 3 minutes to obtain a fibrous material.

[0068] [Example 2] (Preparation of fiber materials) A resin composition was prepared by mixing and dissolving 50.0 parts by mass of the copolymer obtained in Synthesis Example 1, 50.0 parts by mass of phenol novolac type epoxy resin (Epiclon N-770, manufactured by DIC Corporation, epoxy equivalent 180-200 g / eq), and 1900.0 parts by mass of methyl ethyl ketone. Next, a 170mm x 170mm test cloth weighing approximately 6g was dipped in 20g of the resin composition per cloth. After processing, the cloth was dried in a fume hood to evaporate the solvent. After evaporation, the obtained test cloth was sandwiched between a Teflon woven sheet (EBM, product name: Thick Baking Sheet, thickness 0.1mm) and a 2mm thick stainless steel metal plate, and heated in a hot press set to 270°C under a pressure of 2MPa for 3 minutes to obtain a fibrous material.

[0069] [Example 3] (Preparation of fiber materials) A resin composition was prepared by mixing and dissolving 50.0 parts by mass of the copolymer obtained in Synthesis Example 2, 50.0 parts by mass of phenol novolac type epoxy resin (Epiclon N-770, manufactured by DIC Corporation, epoxy equivalent 180-200 g / eq), and 1900.0 parts by mass of methyl ethyl ketone. Next, a 170mm x 170mm test cloth weighing approximately 6g was dipped in 20g of the resin composition per cloth. After processing, the cloth was dried in a fume hood to evaporate the solvent. After evaporation, the obtained test cloth was sandwiched between a Teflon woven sheet (EBM, product name: Thick Baking Sheet, thickness 0.1mm) and a 2mm thick stainless steel metal plate, and heated in a hot press set to 270°C under a pressure of 2MPa for 3 minutes to obtain a fibrous material.

[0070] [Comparative Example 1] (Preparation of fiber materials) A 170mm x 170mm test cloth weighing approximately 6g was sandwiched between a Teflon woven sheet (EBM, product name: Thick Baking Sheet, thickness 0.1mm) and a 2mm thick stainless steel metal plate. This was then heat-treated for 3 minutes under a pressure of 2MPa using a hot press set to 270°C to obtain a fibrous material that was not dipped in a resin composition.

[0071] [Comparative Example 2] (Preparation of fiber materials) A resin composition was prepared by mixing and dissolving 50.0 parts by mass of the copolymer obtained in Synthesis Example 3, 50.0 parts by mass of phenol novolac type epoxy resin (Epiclon N-770, manufactured by DIC Corporation, epoxy equivalent 180-200 g / eq), and 1900.0 parts by mass of methyl ethyl ketone. A 170mm x 170mm test cloth weighing approximately 6g was dipped in 20g of the resin composition. After processing, the cloth was dried in a fume hood to evaporate the solvent. After evaporation, the obtained test cloth was sandwiched between a Teflon woven sheet (EBM, product name: Thick Baking Sheet, thickness 0.1mm) and a 2mm thick stainless steel metal plate, and heated in a hot press set to 270°C under a pressure of 2MPa for 3 minutes to obtain a fibrous material.

[0072] [Comparative Example 3] (Preparation of fiber materials) A resin composition was prepared by mixing and dissolving 100.0 parts by mass of the copolymer obtained in Synthesis Example 1 and 1900.0 parts by mass of methyl ethyl ketone. Next, a 170mm x 170mm test cloth weighing approximately 6g was dipped in 20g of the resin composition per cloth. After processing, the cloth was dried in a fume hood to evaporate the solvent. After evaporation, the obtained test cloth was sandwiched between a Teflon woven sheet (EBM, product name: Thick Baking Sheet, thickness 0.1mm) and a 2mm thick stainless steel metal plate, and heated in a hot press set to 270°C under a pressure of 2MPa for 3 minutes to obtain a fibrous material.

[0073] [Comparative Example 4] (Preparation of fiber materials) A resin composition was prepared by mixing and dissolving 100.0 parts by mass of the copolymer obtained in Synthesis Example 2 and 1900.0 parts by mass of methyl ethyl ketone. Next, a 170mm x 170mm test cloth weighing approximately 6g was dipped in 20g of the resin composition per cloth. After processing, the cloth was dried in a fume hood to evaporate the solvent. After evaporation, the obtained test cloth was sandwiched between a Teflon woven sheet (EBM, product name: Thick Baking Sheet, thickness 0.1mm) and a 2mm thick stainless steel metal plate, and heated in a hot press set to 270°C under a pressure of 2MPa for 3 minutes to obtain a fibrous material.

[0074] [Comparative Example 5] (Preparation of fiber materials) A resin composition was prepared by mixing and dissolving 100.0 parts by mass of phenol novolac type epoxy resin (Epiclon N-770, manufactured by DIC Corporation, epoxy equivalent 180-200 g / eq) and 1900.0 parts by mass of methyl ethyl ketone. Next, a 170mm x 170mm test cloth weighing approximately 6g was dipped in 20g of the resin composition per cloth. After processing, the cloth was dried in a fume hood to evaporate the solvent. After evaporation, the obtained test cloth was sandwiched between a Teflon woven sheet (EBM, product name: Thick Baking Sheet, thickness 0.1mm) and a 2mm thick stainless steel metal plate, and heated in a hot press set to 270°C under a pressure of 2MPa for 3 minutes to obtain a fibrous material.

[0075] [Evaluation of bending strength] A resin solution was prepared by dissolving polyamide resin in methyl ethyl ketone to a solid content of 5% by mass. Approximately 6g of the fiber material obtained in the examples and comparative examples was cut into this solution and dipped in 40g of the polyamide resin solution. The sheet was then air-dried to obtain a processed sheet. Two of these processed sheets were stacked together and heat-treated at 270°C under a pressure of 2MPa for 3 minutes to obtain a plate-shaped molded material. Using the obtained molding material, test specimens were cut to a width of 20 mm and a length of 85 mm in accordance with JIS K-7171 (ISO178). The bending strength (MPa) of these test specimens was measured under conditions of a span of 26 mm and a speed of 0.8 mm / min. The evaluation results are shown in Table 1 (hot press at 270°C). Furthermore, the bending strength is preferably 60 MPa or higher, more preferably 80 MPa or higher, even more preferably 100 MPa or higher, and particularly preferably between 100 MPa and 150 MPa. When the bending strength is within the above range, it is possible to satisfy the mechanical properties (mechanical strength) required for applications such as automobiles, which is preferable.

[0076] [Table 1]

[0077] Based on the evaluation results above, it was confirmed that in all examples, the flexural strength was high, and by preparing the fiber material using a resin composition as a sizing agent, the adhesion between the polyamide resin and the fiber material was high, resulting in excellent mechanical strength. In particular, in Examples 1 to 3, it was confirmed that setting the heating temperature to a high 270°C when preparing the fiber material resulted in improved wettability of the sizing agent to the surface of the test fabric during drying, and thus improved flexural strength.

[0078] On the other hand, the evaluation results above confirmed that in Comparative Example 1, the flexural strength was significantly inferior because the molding material was prepared by dipping a polyamide resin into a fiber material that did not use a resin composition and was not subjected to dipping with a resin composition. Furthermore, in Comparative Example 2, an acrylic acid-acrylic copolymer was used instead of maleic anhydride-acrylic copolymer, in Comparative Examples 3 and 4, epoxy resin was not used, and in Comparative Example 5, epoxy resin was used but maleic anhydride-acrylic copolymer was not used. As a result, it was confirmed that Comparative Examples 2 to 5 had lower flexural strength and inferior mechanical strength compared to the Examples.

Claims

1. A resin composition containing epoxy resin and maleic anhydride / acrylic copolymer, The epoxy resin is an epoxy resin having a glycidyloxyaryl structure in its molecular structure. The epoxy equivalent of the epoxy resin is 150 to 300 g / eq. The maleic anhydride-acrylic copolymer is a copolymer in which the content ratio of maleic anhydride and acrylic monomers is 70 to 100% by mass, relative to 100% by mass of the total amount of monomer components. The acid value of the maleic anhydride-acrylic copolymer is 100 to 500 mg KOH / g. A resin composition in which the content ratio (mass ratio) of the epoxy resin and the maleic anhydride / acrylic copolymer is 20 / 80 to 80 / 20.

2. A resin composition according to claim 1, and a fiber material containing reinforcing fibers.

3. The fiber material according to claim 2, wherein the reinforcing fiber is a carbon fiber.

4. A molding material comprising the fibrous material described in claim 2 or 3 and a thermoplastic resin.

5. The molding material according to claim 4, wherein the thermoplastic resin is a polyamide resin.

6. The molding material according to claim 5, wherein the bending strength is 60 MPa or more.

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