Molding materials and molded products

Abstract

To provide a molding material excellent in the impregnation of a fiber bundle of carbon fibers with respect to a resin component and excellent in the fillability with respect to a mold, and to provide a molded article containing a cured product of the molding material.SOLUTION: A molding material comprises a resin composition containing a resin component and a fiber bundle of carbon fibers. A median X and a standard deviation Y measured by testing the fiber bundle of the carbon fibers have a predetermined relation.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a molding material and a molded article, and more particularly to a molding material and a molded article containing a cured product of the molding material. [Background technology]

[0002] Conventionally, molded articles made from molding materials containing carbon fiber have been used in various fields such as aircraft, automobiles, and sports applications because of their excellent specific strength and specific modulus of elasticity.

[0003] Among molding materials containing carbon fiber, SMC (sheet molding compound) in particular uses short, discontinuous fibers, which generally poses the problem of lower mechanical properties of fiber-reinforced resin structures compared to molded products that use continuous fibers. However, because the material is made to flow and fill the mold, it is suitable for forming complex shapes with fine irregularities that are difficult to achieve with autoclave molding or RTM molding. Furthermore, because the material is made to flow, the time required for material layering can be reduced and the molding cycle is also short, leading to accelerating adoption in a variety of fields.

[0004] As such a molding material, for example, a carbon fiber reinforced sheet-shaped molding material containing a thermosetting polymer, a vinyl monomer, a thermoplastic polymer, and carbon fiber has been proposed (see, for example, Patent Document 1 below).

[0005] The carbon fibers blended in the molding material are fiber bundles of carbon fibers that have been opened and then separated by passing them through a circular blade at equal intervals (see, for example, Example 12 of Patent Document 1 below). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-197295 Summary of the Invention [Problem to be solved by the invention]

[0007] In Example 12 of Patent Document 1, fiber bundles of carbon fibers that have been split at equal intervals after fiber-opening processing are used, so the widths of the carbon fiber bundles are uniform. As a result, such carbon fiber bundles are localized in the molding material, and when the carbon fiber bundles overlap, it becomes impossible to ensure appropriate gaps between the carbon fiber bundles. As a result, there is a problem in that the impregnation of the carbon fiber bundles with the resin component (thermosetting polymer) is reduced.

[0008] Furthermore, when such a molding material is molded in a mold, it is necessary to improve the filling ability of the molding material into the mold. However, in the method described in Example 12 of Patent Document 1, the carbon fibers are separated into fiber bundles of uniform width, and therefore, when the material flows during molding, the carbon fibers become entangled with each other, reducing the fluidity.

[0009] An object of the present invention is to provide a molding material that exhibits excellent impregnation of carbon fiber bundles into a resin component and excellent mold filling properties, and to provide a molded article containing a cured product of the molding material. [Means for solving the problem]

[0010] The present invention [1] is a molding material comprising a resin composition containing a resin component and a fiber bundle of carbon fiber, wherein the median X and standard deviation Y of the fiber bundle of the carbon fiber measured by the following test satisfy the relationships of the following formulas (1) to (4): Y>0.5X (1) Y<0.5X+4000 (2) X>2000 (3) X<8000 (4) Test: Using a defibrator, the carbon fiber bundle is defibrated, and 100 defibrated carbon fiber bundles are randomly extracted from the defibrated carbon fiber bundle. The mass (m) of each extracted carbon fiber bundle and the fiber length (l) of each carbon fiber bundle are measured, and the number of bundled fibers (n) of the defibrated carbon fiber bundle is calculated from the obtained mass (m) and fiber length (l) based on the following formula (5), and the median and standard deviation of these bundled fibers are calculated. n = (m × N × 1000) / (M × l) (5) (In the formula, n represents the number of fibers (K) in the carbon fiber bundle after defibration, m represents the mass (mg) of the carbon fiber bundle after defibration, N represents the number of fibers (K) in the carbon fiber bundle before defibration, M represents the fiber weight (g / 1000m) of the carbon fiber bundle before defibration, and 1 represents the fiber length (mm) of the carbon fiber bundle after defibration.) The present invention [2] includes the molding material according to the above [1], in which the bulk density of the fiber bundle of the carbon fiber is 0.15 g / ml or more and 0.3 g / ml or less.

[0011] The present invention [3] includes the molding material according to the above [1] or [2], in which the resin component includes a reaction product of a vinyl ester and an acid anhydride, and the resin composition includes a thickener.

[0012] The present invention [4] includes the molding material according to the above [3], in which the thickener is magnesium oxide.

[0013] The present invention [5] includes the molding material according to the above [3] or [4], in which the compounding ratio of the acid anhydride is 0.6 mol or more and 1.4 mol or less per 1 mol of the vinyl ester.

[0014] The present invention [6] includes the molding material according to any one of the above [3] to [5], wherein the vinyl ester is a reaction product of an epoxy resin and an unsaturated monobasic acid, and the epoxy equivalent of the epoxy resin is 200 or more and 500 or less.

[0015] The present invention [7] comprises the molding material according to any one of the above [1] to [6], wherein the blending ratio of the carbon fiber bundles is 40 mass% or more and 65 mass% or less with respect to the total amount of the resin composition and the carbon fiber bundles.

[0016] The present invention [8] includes a molded article containing a cured product of the molding material according to any one of the above [1] to [7]. [Effects of the Invention]

[0017] The molding material of the present invention contains fiber bundles of carbon fibers, and the median X and standard deviation Y of the fiber bundles of carbon fibers measured by a predetermined test have a predetermined relationship.

[0018] Therefore, this molding material has excellent impregnation properties of the carbon fiber bundles into the resin component and excellent filling properties into a mold.

[0019] The molded article of the present invention contains a cured product of the molding material of the present invention, and therefore has excellent surface smoothness and is suppressed from warping. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a graph showing the relationship between the median X and the standard deviation Y. [Figure 2] FIG. 2 is a graph showing the relationship between the median X and the standard deviation Y in Examples 1, 3, 5, 7, 8, 9, 12, and 15, as well as Comparative Examples 1 to 4 and 7 to 13. DETAILED DESCRIPTION OF THE INVENTION

[0021] The molding material of the present invention comprises a resin composition containing a resin component, and fiber bundles of carbon fibers having a predetermined median and a predetermined standard deviation measured in a test (described later).

[0022] The resin component includes a double bond-containing curable polymer and a polymerizable monomer.

[0023] Examples of the double bond-containing curable polymer include vinyl esters and unsaturated polyesters, and preferably vinyl esters.

[0024] Vinyl esters are the reaction products of epoxy resins and unsaturated monobasic acids.

[0025] Examples of epoxy resins include bisphenol-type epoxy resins and novolac-type epoxy resins, and preferably bisphenol-type epoxy resins.

[0026] The bisphenol-type epoxy resin is represented by the following general formula (1).

[0027] [ka] (In the formula, Y 1 represents any one of -C(CH3)2-, -CH2-, -O-, -S-, and -(O=S=O)-, and n represents an integer of 0 to 5. Examples of such bisphenol type epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, and bisphenol S type epoxy resins, and preferably bisphenol A type epoxy resins.

[0028] The epoxy resin can also be modified with a phenolic compound such as bisphenol A, bisphenol F, or bisphenol S.

[0029] To modify an epoxy resin with a phenolic compound, the epoxy resin is reacted with the phenolic compound.

[0030] The mixing ratio of the phenol compound relative to 1 mole of the epoxy resin is, for example, 0.1 mole or more, preferably 0.3 mole or more, and for example, 0.6 mole or less, preferably 0.5 mole or less.

[0031] In the above reaction, the reaction temperature is, for example, 100°C or higher, preferably 130°C or higher, and for example, 200°C or lower, and the reaction time is, for example, 1 hour or higher, preferably 2 hours or higher, and for example, 10 hours or lower.

[0032] In the above reaction, a catalyst may be added, if necessary.

[0033] Examples of the catalyst include amines such as triethylamine and benzyldimethylamine, ammonium salts such as tetramethylammonium chloride and triethylbenzylammonium chloride, imidazoles such as 2-ethyl-4-imidazole, amides, pyridines, phosphines such as triphenylphosphine, phosphonium salts such as tetraphenylphosphonium bromide and ethyltriphenylphosphonium bromide, sulfonium salts, sulfonic acids, and organic metal salts such as zinc octoate, and preferably ammonium salts, and more preferably triethylbenzylammonium chloride.

[0034] The catalysts can be used alone or in combination of two or more.

[0035] The mixing ratio of the catalyst relative to 100 parts by mass of the epoxy resin is, for example, 0.01 parts by mass or more, and for example, 2.0 parts by mass or less, preferably 1.5 parts by mass or less.

[0036] This allows the epoxy resin to be modified with the phenol compound.

[0037] As the epoxy resin, preferably, an epoxy resin modified with a phenol compound is used, and more preferably, a bisphenol A type epoxy resin modified with bisphenol A is used.

[0038] The epoxy resins can be used alone or in combination of two or more.

[0039] The epoxy equivalent of the epoxy resin is, for example, 150 or more, preferably 200 or more, more preferably 250 or more, from the viewpoint of improving the bending strength of a molded article (described later), and is, for example, 600 or less, preferably 500 or less, more preferably 450 or less, from the viewpoint of improving heat resistance.

[0040] When two types of epoxy resins are used in combination, the above-mentioned epoxy equivalent weight is the epoxy equivalent weight of all epoxy resins obtained by multiplying the epoxy equivalent weight of each epoxy resin by the mass ratio of each epoxy resin to the total amount of epoxy resins and adding them together.

[0041] Examples of unsaturated monobasic acids include monocarboxylic acids such as (meth)acrylic acid, crotonic acid, cinnamic acid, and sorbic acid, and reaction products of dibasic acid anhydrides with alcohols having at least one unsaturated group in the molecule. Note that (meth)acrylic is synonymous with methacrylic and / or acrylic.

[0042] Examples of dibasic acid anhydrides include maleic anhydride, succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride.

[0043] Examples of alcohols having an unsaturated group include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, pentaerythritol tri(meth)acrylate, and glycerin di(meth)acrylate.

[0044] The unsaturated monobasic acids can be used alone or in combination of two or more kinds.

[0045] As the unsaturated monobasic acid, preferably, a monocarboxylic acid is used, more preferably, (meth)acrylic acid is used, and further preferably, methacrylic acid is used.

[0046] To obtain the vinyl ester, an epoxy resin is reacted with an unsaturated monobasic acid.

[0047] In the above reaction, an addition reaction occurs between the epoxy group of the epoxy resin and the unsaturated monobasic acid.

[0048] In the above reaction, the equivalent weight of the carboxyl group of the unsaturated monobasic acid relative to the epoxy group of the epoxy resin is, for example, 0.8 or more, preferably 0.9 or more, and for example, 1.5 or less, preferably 1.1 or less.

[0049] In the above reaction, the reaction temperature is, for example, 80°C or higher, preferably 100°C or higher, and for example, 150°C or lower, preferably 130°C or lower, and the reaction time is, for example, 1 hour or higher, preferably 2 hours or higher, and for example, 10 hours or lower.

[0050] In the above reaction, the above-mentioned catalyst (preferably an ammonium salt, more preferably triethylbenzylammonium chloride) can be added, if necessary.

[0051] The catalyst is mixed in an amount of, for example, 0.01 part by mass or more, preferably 0.03 part by mass or more, and for example, 0.5 part by mass or less, preferably 0.1 part by mass or less, per 100 parts by mass of the epoxy resin.

[0052] In the above reaction, a polymerization inhibitor may be added, if necessary.

[0053] Examples of the polymerization inhibitor include hydroquinone compounds such as hydroquinone, methylhydroquinone, and t-butylhydroquinone; benzoquinone compounds such as p-benzoquinone and methyl-p-benzoquinone; catechol compounds such as t-butylcatechol; phenol compounds such as 2,6-di-t-butyl-4-methylphenol and 4-methoxyphenol; and 1-oxyl-2,2,6,6-tetramethylpiperidine, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-ol, 4-hydroxy-2,2, 6,6-tetrapiperidine-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-acetate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-2-ethylhexanoate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-stearate, 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-4-t-butylbenzoate, bis(1-oxyl-2,2,6,6-tetramethylpiperidin) Bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) succinate, Bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipate, Bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, Bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butylmalonate, Bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) phthalate, Bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) isophthalate, Bis(1-oxyl-2,2,6 ,6-tetramethylpiperidin-4-yl) terephthalate, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) hexahydroterephthalate, N,N'-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) adipamide, N-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) caprolactam, N-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) dodecyl succinimide, 2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,Examples of the N-oxyl compounds include N-oxyl compounds such as 1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)-s-triazine and 1-oxyl-2,2,6,6-tetramethylpiperidin-4-one, and preferably hydroquinone compounds, more preferably hydroquinone.

[0054] The polymerization inhibitors can be used alone or in combination of two or more.

[0055] The mixing ratio of the polymerization inhibitor relative to 100 parts by mass of the epoxy resin is, for example, 0.01 part by mass or more, preferably 0.03 part by mass or more, and for example, 0.5 part by mass or less, preferably 0.1 part by mass or less.

[0056] This gives a vinyl ester.

[0057] Such vinyl esters can also be modified with acid anhydrides.

[0058] That is, examples of vinyl esters include vinyl esters modified with acid anhydrides (hereinafter referred to as acid-modified vinyl esters) and vinyl esters not modified with acid anhydrides (hereinafter referred to as unmodified vinyl esters).

[0059] Acid-modified vinyl esters are reaction products of vinyl esters and acid anhydrides.

[0060] Examples of acid anhydrides include maleic anhydride, succinic anhydride, and phthalic anhydride, with maleic anhydride being preferred.

[0061] To obtain an acid-modified vinyl ester, a vinyl ester is reacted with an acid anhydride.

[0062] In the above reaction, the mixing ratio of the acid anhydride relative to 1 mole of the vinyl ester is, for example, 0.6 moles or more, preferably 0.8 moles or more, and for example, 1.4 moles or less, preferably 1.2 moles or less.

[0063] When the blending ratio of the acid anhydride is equal to or greater than the above lower limit, the viscosity of the resin composition can be increased to a level suitable for heat compression molding.

[0064] When the blending ratio of the acid anhydride is equal to or less than the upper limit, the storage stability is excellent.

[0065] In the above reaction, the reaction temperature is, for example, 60°C or higher and, for example, 100°C or lower, and the reaction time is, for example, 1 hour or higher and, for example, 12 hours or lower, preferably 6 hours or lower.

[0066] This gives an acid-modified vinyl ester.

[0067] The acid value of the acid-modified vinyl ester (measurement method: in accordance with JIS K6901 (2008), the same applies below) is, for example, 40 mgKOH / g or more, preferably 50 mgKOH / g or more, and for example, 100 mgKOH / g or less, preferably 90 mgKOH / g or less.

[0068] The acid value of the unmodified vinyl ester is, for example, 1 mgKOH / g or more, preferably 5 mgKOH / g or more, and for example, 20 mgKOH / g or less, preferably 10 mgKOH / g or less.

[0069] Of these vinyl esters, acid-modified vinyl esters are preferred.

[0070] That is, the resin component preferably contains an acid-modified vinyl ester.

[0071] The mixing ratio of the double bond-containing curable polymer relative to 100 parts by mass of the polymerizable monomer is, for example, 80 parts by mass or more, or preferably 120 parts by mass or more, and for example, 200 parts by mass or less.

[0072] The mixing ratio of the double bond-containing curable polymer relative to 100 parts by mass of the resin component is, for example, 30 parts by mass or more, preferably 40 parts by mass or more, and for example, 65 parts by mass or less.

[0073] When the blending ratio of the double bond-containing curable polymer is equal to or greater than the above lower limit, the viscosity of the resin composition can be increased to a level suitable for heat compression molding.

[0074] When the blending ratio of the double bond-containing curable polymer is equal to or less than the above upper limit, the impregnation of the carbon fiber bundle with the resin component can be improved.

[0075] The polymerizable monomer is a solvent for dissolving the double bond-containing curable polymer, and is also a crosslinkable monomer (reactive diluent) that can crosslink with the double bond-containing curable polymer when the double bond-containing curable resin (described later) is cured. Examples of the polymerizable monomer include styrene-based monomers such as styrene, α-methylstyrene, α-ethylstyrene, vinyltoluene, t-butylstyrene, and chlorostyrene; methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, n-butyl (meth)acrylate; (Meth)acrylic acid alkyl esters such as t-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate; (meth)acrylic acid allyl esters such as allyl (meth)acrylate; (meth)acrylic acid allyl esters such as cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate; ) ring-structure-containing (meth)acrylic acid esters such as dicyclopentenyl acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate; (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; (meth)acrylic acid alkoxyalkyl esters such as 2-methoxyethyl (meth)acrylate and 2-ethoxyethyl (meth)acrylate; (meth)acrylic acid aminoalkyl esters and chloride salts thereof such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate; (meth)acrylic acid fluoroalkyl esters such as trifluoroethyl (meth)acrylate and heptadecafluorodecyl (meth)acrylate; (meth)acrylic acid ester-based monomers such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and pentaerythritol tetra(meth)acrylate;Examples of suitable monomers include polyfunctional (meth)acrylic acid esters such as dipentaerythritol hexa(meth)acrylate, and allyl monomers such as glycerin monoallyl ether, pentaerythritol diallyl ether, pentaerythritol monoallyl ether, and trimethylolpropane monoallyl ether. Preferred examples include styrene-based monomers and ring-containing (meth)acrylic acid esters, and more preferred examples include styrene and benzyl methacrylate.

[0076] The polymerizable monomers can be used alone or in combination of two or more kinds.

[0077] The mixing ratio of the polymerizable monomer relative to 100 parts by mass of the resin component is, for example, 20 parts by mass or more and, for example, 70 parts by mass or less.

[0078] The resin component preferably also contains a low-profile agent.

[0079] When a molded article (described later) is obtained using this molding material, the low-profile agent is blended to suppress cure shrinkage and heat shrinkage of the molded article (described later).

[0080] Examples of low shrinkage agents include polyethylene, polystyrene, styrene-based thermoplastic elastomers, crosslinked polystyrene, polyvinyl acetate-polystyrene block copolymers, polyvinyl acetate, polymethyl methacrylate, saturated polyester resins, and the like.

[0081] Examples of styrene-based thermoplastic elastomers include styrene-butadiene block copolymer elastomers, styrene-isoprene block copolymer elastomers, styrene-ethylene / butylene block copolymer elastomers, and styrene-ethylene / propylene-styrene block copolymer elastomers, and preferably styrene-ethylene / propylene-styrene block copolymer elastomers. Commercially available styrene-based thermoplastic elastomers include D1101, D1102, D1155, DKX405, DKX410, DKX415, D1192, D1161, D1171, G1651, G1652, G1654, G1701, and G1730 (all manufactured by Kraton Elastomers), Asaprene T411, Asaprene T432, Tufprene A, Tufprene 125, Tufprene 126S, Tufprene 315, Tufprene 912, Tuftec H1141, Tuftec H1041, Tuftec H1043, and Tuftec H1052 (all manufactured by Asahi Kasei Corporation), and Septon 1001 and 1201 (all manufactured by Kuraray Co., Ltd.).

[0082] The styrene content in the styrene-based thermoplastic elastomer is, for example, 5% by mass or more and, for example, 50% by mass or less.

[0083] As the low shrinkage agent, preferably, styrene-based thermoplastic elastomer, saturated polyester resin, and polyvinyl acetate are used.

[0084] The low profile agents can be used alone or in combination of two or more.

[0085] The mixing ratio of the low profile agent relative to 100 parts by mass of the resin component is, for example, 1 part by mass or more, or preferably 3 parts by mass or more, and for example, 30 parts by mass or less, or preferably 20 parts by mass or less.

[0086] When the blending ratio of the low shrinkage agent is equal to or greater than the above lower limit, it is possible to suppress cure shrinkage and heat shrinkage of the molded article (described later).

[0087] If the blending ratio of the low profile agent is equal to or less than the above upper limit, separation of the resin components can be suppressed, and as a result, a molded product (described later) with a good appearance can be obtained.

[0088] The resin composition can be obtained by blending the respective components of the resin component, specifically, the double bond-containing curable polymer, the polymerizable monomer, and the low shrinkage agent which is blended as needed, in the blending ratios described above.

[0089] This gives a resin composition.

[0090] If necessary, the resin composition may contain additives such as a polymerization inhibitor, a polymerization initiator, a wetting and dispersing agent, a separation prevention agent, a mold release agent, a filler, a thickener, a colorant, a flame retardant, etc. These additives may be used alone or in combination of two or more.

[0091] The polymerization inhibitor is not particularly limited, and examples thereof include PBQ (parabenzoquinone), MTBHQ (mono t-butylhydroquinone), BHT (di t-butylhydroxytoluene or 2,5-di t-butyl-4-methylphenol), HQ (hydroquinone), TBC (t-butylcatechol), and 4-hydroxy-2,2,6,6-tetramethyl-4-oxopiperidine-1-oxyl free radical, and preferably PBQ (parabenzoquinone).

[0092] The polymerization inhibitors can be used alone or in combination of two or more.

[0093] The mixing ratio of the polymerization inhibitor relative to 100 parts by mass of the resin component is, for example, 0.01 parts by mass or more, and for example, 5 parts by mass or less, preferably 1 part by mass or less.

[0094] Examples of the polymerization initiator include benzoyl peroxide, t-butylperoxyisopropyl monocarbonate, t-amylperoxyisopropyl monocarbonate, t-hexylperoxyisopropyl monocarbonate, 1,1-bis(t-butylperoxy)cyclohexane, t-butylperoxy-2-ethylhexanoate, amylperoxy-2-ethylhexanoate, 2-ethylhexylperoxy-2-ethylhexanoate, t-butylperoxybenzoate, and t-hexyl Examples of the peroxide include peroxybenzoate and t-hexyl peroxyacetate, and preferred examples include peroxyisopropyl monocarbonate such as t-butylperoxyisopropyl monocarbonate, t-amylperoxyisopropyl monocarbonate, t-hexylperoxyisopropyl monocarbonate, and t-butyl peroxybenzoate, and preferred examples include t-butylperoxyisopropyl monocarbonate and t-butyl peroxybenzoate.

[0095] The mixing ratio of the polymerization initiator relative to 100 parts by mass of the resin component is, for example, 0.5 parts by mass or more, preferably 0.7 parts by mass or more, and for example, 5 parts by mass or less, preferably 3 parts by mass or less.

[0096] The polymerization initiators can be used alone or in combination of two or more.

[0097] A known curing accelerator may also be used in combination with the polymerization initiator.

[0098] Examples of the curing accelerator include organometallic compounds of cobalt, copper, and manganese, such as the octoates, naphthenates, and acetylacetonates of the respective compounds.

[0099] The mixing ratio of the curing accelerator relative to 100 parts by mass of the resin component is, for example, 0.01 part by mass or more and, for example, 1 part by mass or less.

[0100] The curing accelerators can be used alone or in combination of two or more.

[0101] The wetting and dispersing agent is blended to improve the wettability of the resin component with the reinforcing fiber or filler, and examples of the wetting and dispersing agent include known wetting and dispersing agents such as phosphate polyester. In addition, commercially available wetting and dispersing agents can be used, specifically, BYK-W996 (manufactured by BYK-Chemie) and the like.

[0102] The mixing ratio of the wetting and dispersing agent relative to 100 parts by mass of the resin component is, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and for example, 10 parts by mass or less, preferably 3 parts by mass or less.

[0103] The wetting and dispersing agents can be used alone or in combination of two or more.

[0104] The anti-separation agent is blended to prevent separation of the resin composition, and examples thereof include a block copolymer of styrene and vinyl acetate. Commercially available anti-separation agents can be used, specifically, BYK-W972 (manufactured by BYK-Chemie).

[0105] The mixing ratio of the separation preventing agent relative to 100 parts by mass of the resin component is, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and for example, 10 parts by mass or less, preferably 3 parts by mass or less.

[0106] The anti-separation agents can be used alone or in combination of two or more.

[0107] Examples of the release agent include fatty acids such as stearic acid and lauric acid, fatty acid metal salts such as zinc stearate and calcium stearate, and compounds such as paraffin, liquid wax, fluoropolymers, silicon-based polymers, and alkylammonium salts, and preferably fatty acid metal salts, and more preferably zinc stearate.

[0108] The mixing ratio of the release agent relative to 100 parts by mass of the resin component is, for example, 1 part by mass or more, or preferably 3 parts by mass or more, and for example, 10 parts by mass or less.

[0109] The release agents can be used alone or in combination of two or more.

[0110] Examples of fillers include oxides such as alumina and titania, hydroxides such as magnesium hydroxide and aluminum hydroxide, carbonates such as calcium carbonate, sulfates such as barium sulfate, silica (e.g., crystalline silica, fused silica, fumed silica, dry silica (Aerosil), etc.), glass powder, hollow fillers such as glass balloons, silica balloons, and alumina balloons, silicates such as silica sand, diatomaceous earth, mica, clay, kaolin, and talc, fluorides such as fluorite, phosphates such as calcium phosphate, inorganic fillers such as clay minerals such as smectite, conductive fibers such as milled carbon fiber, conductive particles, and conductive fillers such as carbon nanotubes. Preferably, carbonates, hollow fillers, and conductive fillers are used. More preferably, calcium carbonate, glass balloons, and milled carbon fiber are used.

[0111] The blending ratio of the filler is, for example, 1 part by mass or more, preferably 10 parts by mass or more, and for example, 100 parts by mass or less, preferably 50 parts by mass or less, more preferably 30 parts by mass or less, per 100 parts by mass of the resin component.

[0112] The fillers can be used alone or in combination of two or more.

[0113] The thickener is blended to thicken the resin composition to a viscosity suitable for heat compression molding, and is preferably blended before (preferably immediately before) impregnating the resin composition into reinforcing fibers (described later). Examples of thickeners include alkaline earth metal oxides such as magnesium oxide, alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide, and polyisocyanate compounds such as diphenylmethane diisocyanate (MDI).

[0114] The thickener is selected depending on the type of double bond-containing curable polymer. For example, when the double bond-containing curable polymer is an unmodified vinyl ester, a diisocyanate such as diphenylmethane diisocyanate is selected as the thickener. Also, for example, when the double bond-containing curable polymer is an acid-modified vinyl ester, magnesium oxide is selected as the thickener.

[0115] When the double bond-containing curable polymer is an acid-modified vinyl ester and the thickener is magnesium oxide, the composition has excellent handling properties and flowability.

[0116] When the double bond-containing curable polymer is an unmodified vinyl ester and the thickener is diphenylmethane diisocyanate, the blending ratio of the thickener is, for example, 1 part by mass or more, preferably 5 parts by mass or more, and for example, 20 parts by mass or less, preferably 15 parts by mass or less, relative to 100 parts by mass of the resin component. When the double bond-containing curable polymer is an acid-modified vinyl ester and the thickener is magnesium oxide, the blending ratio is, for example, 0.1 part by mass or more, preferably 0.5 parts by mass or more, and for example, 5 parts by mass or less, relative to 100 parts by mass of the resin component.

[0117] The thickeners can be used alone or in combination of two or more.

[0118] The colorant is not particularly limited, and examples thereof include titanium oxide and polyester toner (polyester colorant containing titanium oxide and / or carbon black).

[0119] The mixing ratio of the colorant relative to 100 parts by mass of the resin component is, for example, 1 part by mass or more, or preferably 5 parts by mass or more, and for example, 20 parts by mass or less.

[0120] The colorants can be used alone or in combination of two or more.

[0121] Examples of the flame retardant include halogen-based flame retardants such as bromine-based flame retardants, and non-halogen-based flame retardants such as phosphorus-based flame retardants, inorganic flame retardants, and nitrogen compound-based flame retardants.

[0122] The mixing ratio of the flame retardant relative to 100 parts by mass of the resin component is, for example, 1 part by mass or more, preferably 5 parts by mass or more, and for example, 50 parts by mass or less, preferably 20 parts by mass or less.

[0123] The flame retardants can be used alone or in combination of two or more.

[0124] If necessary, the resin composition may contain additives such as a pattern material, an antibacterial agent, a hydrophilic agent, a photocatalyst, an ultraviolet absorber, an ultraviolet stabilizer, a silane coupling agent, an antistatic agent, a thixotropic agent, a thixotropic stabilizer, and a polymerization accelerator, provided that the effects of the present invention are not impaired. These additives may be used alone or in combination of two or more.

[0125] The viscosity of the resin composition at 25°C is, for example, 0.1 Pa·s or more, preferably 0.5 Pa·s or more, more preferably 0.7 Pa·s or more, and for example, 10 Pa·s or less, preferably 5 Pa·s or less.

[0126] The method for measuring viscosity will be described in detail in the examples below.

[0127] In the above explanation, a resin composition is obtained by blending a double bond-containing curable polymer, a polymerizable monomer, an optional low profile agent, and optional additives. However, it is also possible to first prepare a double bond-containing curable resin by dissolving a double bond-containing curable polymer in a polymerizable monomer, and then blend the obtained double bond-containing curable resin with the polymerizable monomer, an optional low profile agent, and optional additives.

[0128] In preparing the double bond-containing curable polymer, the double bond-containing curable polymer and the polymerizable monomer are blended, and the above-mentioned additives may also be blended as needed.

[0129] The carbon fiber bundle is a fiber bundle formed by bundling a plurality of carbon fibers.

[0130] Furthermore, the carbon fiber bundles are defibrated beforehand when the molding material is impregnated, that is, such carbon fiber bundles are defibrated carbon fiber bundles.

[0131] Specifically, the carbon fiber bundle after defibration is obtained by defibrating the raw material of the carbon fiber bundle (the carbon fiber bundle before defibration) using a known defibrator so that the median and standard deviation, which will be described later, have a predetermined relationship and convergence number.

[0132] The number of fibers in the fiber bundle of the carbon fiber before defibration is, for example, 3,000 or more, preferably 6,000 or more, more preferably 12,000 or more, and for example, 60,000 or less, preferably 50,000 or less.

[0133] If the number of bundles is equal to or greater than the lower limit, when the carbon fiber bundles overlap each other, an appropriate gap can be secured between the carbon fiber bundles, thereby improving the impregnation of the carbon fiber bundles with the resin component. In addition, interference between the carbon fiber bundles can be suppressed, improving the flowability during molding.

[0134] Furthermore, if the number of bundles is equal to or less than the upper limit, the carbon fiber bundles can be prevented from becoming too thick, thereby improving the impregnation of the carbon fiber bundles with the resin component, and improving the bending strength and bending modulus of a molded product (described below) obtained using this molding material.

[0135] An example of the defibrator is the defibrator described in JP 2019-065405 A.

[0136] The number of bundled fibers in the resulting carbon fiber bundle after defibration has a predetermined relationship between the median X and standard deviation Y measured by the test described below.

[0137] In detail, in the test, a defibrator (for example, the defibrator described in JP 2019-065405 A mentioned above) was used to defibrate a carbon fiber bundle, and 100 defibrated carbon fiber bundles were randomly extracted from the defibrated carbon fiber bundle. The mass (m) of each extracted carbon fiber bundle and the fiber length (l) of each carbon fiber bundle were measured, and the number of bundled fibers (n) of the defibrated carbon fiber bundle was calculated from the obtained mass (m) and fiber length (l) based on the following formula (1), and the median and standard deviation of these bundled fibers were calculated. n = (m × N × 1000) / (M × l) (1) (In the formula, n represents the number of fibers (K) in the carbon fiber bundle after defibration, m represents the mass (mg) of the carbon fiber bundle after defibration, N represents the number of fibers (K) in the carbon fiber bundle before defibration, M represents the fiber weight (g / 1000m) of the carbon fiber bundle before defibration, and 1 represents the fiber length (mm) of the carbon fiber bundle after defibration.) When a carbon fiber bundle (a carbon fiber bundle before defibration) is defibrated using the defibration device described in JP 2019-065405 A, the rotation speed of the rotating shaft in the upper defibration mechanism, the rotation speed of the rotating shaft in the middle defibration mechanism, and the rotation speed of the rotating shaft in the lower defibration mechanism are adjusted to 100 rpm or more, preferably 400 rpm or more, more preferably 800 rpm or more, and for example, 3000 rpm or less, preferably 2500 rpm or less.

[0138] If the rotation speed is reduced, the defibration processing efficiency decreases, so the median X and standard deviation Y can be increased, and if the rotation speed is increased, the defibration processing efficiency improves, so the median X and standard deviation Y can be decreased.

[0139] Specifically, the median X and the standard deviation Y satisfy the relationships of the following formulas (2) to (5). Y>0.5X (2) Y<0.5X+4000 (3) X>2000 (4) X<8000 (5) In other words, this means that the median X and standard deviation Y are within the range indicated by the diagonal lines in FIG.

[0140] If the median X and standard deviation Y are within these ranges, localization of the defibrated carbon fiber bundles in the molding material can be suppressed, and when the defibrated carbon fiber bundles overlap each other, appropriate gaps can be secured between the defibrated carbon fiber bundles, thereby improving the impregnation of the defibrated carbon fiber bundles with the resin component. Also, from the viewpoint of entanglement of the carbon fiber bundles, the mold filling ability can be improved.

[0141] On the other hand, if the median X and the standard deviation Y do not satisfy the above formula (2) (more specifically, area A in FIG. 1), the filling ability into the mold decreases in terms of entanglement of the carbon fiber bundles.

[0142] Furthermore, if the median X and standard deviation Y do not satisfy the above formula (3) (more specifically, area B in Figure 1), the fiber bundles of the defibrated carbon fibers will be localized in the molding material, and when the defibrated carbon fiber bundles overlap each other, it will be impossible to ensure appropriate gaps between the defibrated carbon fiber bundles, which will reduce the impregnation of the defibrated carbon fiber bundles with the resin component.

[0143] Furthermore, if the median X does not satisfy the above formula (4) (more specifically, region C in FIG. 1), the filling ability into the mold will decrease from the viewpoint of entanglement of the carbon fiber bundles.

[0144] Furthermore, if the median X does not satisfy the above formula (5) (more specifically, area D in Figure 1), the fiber bundles of the defibrated carbon fibers will be localized in the molding material, and when the fiber bundles of the defibrated carbon fibers overlap each other, it will be impossible to ensure appropriate gaps between the fiber bundles of the defibrated carbon fibers, which will reduce the impregnation of the fiber bundles of the defibrated carbon fibers with the resin component.

[0145] Preferably, the median X and the standard deviation Y satisfy the relationships of the following formulas (6) to (9). Y>0.5X (6) Y<0.5X+2000 (7) X>2000 (8) X<5000 (9) If the median X and the standard deviation Y satisfy the relationships of the above formulas (6) to (9), entanglement of the carbon fiber bundles can be effectively prevented, and in the case where the defibrated carbon fiber bundles are localized in the molding material and overlap with each other, appropriate gaps can be further ensured between the defibrated carbon fiber bundles.

[0146] The bulk density of the carbon fiber bundle is, for example, 0.15 g / ml or more, preferably 0.18 g / ml or more, and for example, 0.3 g / ml or less, preferably 0.25 g / ml or less.

[0147] When the bulk density of the carbon fiber bundle is equal to or greater than the above lower limit, the generation of fluff in the carbon fiber bundle can be suppressed.

[0148] Furthermore, if the bulk density of the carbon fiber bundles is equal to or less than the above upper limit, it is possible to prevent the carbon fiber bundles from being localized in the molding material, and when the carbon fiber bundles overlap each other, it is possible to ensure appropriate gaps between the carbon fiber bundles, thereby improving the impregnation of the carbon fiber bundles with the resin component.

[0149] The method for measuring the bulk density will be described in detail in the Examples below.

[0150] The molding material is obtained by blending fiber bundles of carbon fibers into a resin composition.

[0151] Specifically, the molding material is obtained, for example, as a sheet-like molding material by impregnating a fiber bundle of carbon fibers with a resin composition.

[0152] Methods for preparing the molding material include known methods, such as SMC (sheet molding compound), TMC (thick molding compound), and BMC (bulk molding compound), with SMC being preferred.

[0153] The blending ratio of the carbon fiber bundles relative to the total amount of the resin composition and the carbon fiber bundles is, for example, 40 mass % or more, preferably 50 mass % or more, and for example, 65 mass % or less.

[0154] If the blending ratio of the carbon fiber bundles is equal to or greater than the above lower limit, the specific strength and specific rigidity of the molded article obtained using this molding material can be improved.

[0155] Furthermore, if the blending ratio of the carbon fiber bundles is equal to or less than the above upper limit, the impregnation of the carbon fiber bundles with the resin component can be improved.

[0156] This results in a molding material containing the resin composition and fiber bundles of reinforcing fibers.

[0157] If necessary, reinforcing fibers (excluding fiber bundles of carbon fibers) can also be blended into the molding material.

[0158] Examples of reinforcing fibers (excluding fiber bundles of carbon fibers) include inorganic fibers such as glass fibers, metal fibers, and ceramic fibers; organic fibers such as polyvinyl alcohol fibers, polyester fibers, polyamide fibers, fluororesin fibers, and phenol fibers; and natural fibers such as hemp and kenaf.

[0159] The blending ratio of the reinforcing fibers is, for example, 5 mass% or more, preferably 10 mass% or more, more preferably 20 mass% or more, and for example, 50 mass% or less, preferably 40 mass% or less, relative to the total amount of the resin composition and the reinforcing fibers.

[0160] Next, such a molding material is aged, for example, at 20° C. to 50° C. for 8 hours to 120 hours to increase viscosity so that handling properties for hot compression molding (described later) can be improved.

[0161] As a result, the molding material is maintained in a sheet shape, for example. That is, the molding material has a sheet shape.

[0162] Such a molding material contains fiber bundles of carbon fibers having the above-mentioned median X and the above-mentioned standard deviation Y.

[0163] Therefore, the carbon fiber bundles have excellent impregnation properties with the resin component and excellent filling properties in a mold.

[0164] The molded article can be obtained by subjecting the above molding material to heat compression molding using a known method.

[0165] The conditions for the heat compression molding are set appropriately depending on the purpose and application. Specifically, the molding temperature is, for example, 60°C or higher, preferably 100°C or higher, and for example, 200°C or lower, preferably 180°C or lower; and the molding pressure is, for example, 0.1 MPa or higher, preferably 1 MPa or higher, more preferably 5 MPa or higher, and for example, 20 MPa or lower, preferably 15 MPa or lower.

[0166] This causes the molding material to harden and be molded.

[0167] This results in a molded article containing a cured product of the molding material.

[0168] As described above, the molding material contains fiber bundles of carbon fibers having the above-mentioned median X and standard deviation Y, and therefore localization of the fiber bundles of carbon fibers is suppressed during preparation of the molding material. As a result, a molded article containing a cured product of this molding material has excellent surface smoothness and is suppressed from warping.

[0169] The density of the molded article is, for example, 1.2 g / mL or more, preferably 1.3 g / mL or more, more preferably 1.4 g / mL or more, and for example, 1.7 g / mL or less, preferably 1.6 g / mL or less.

[0170] The method for measuring the density will be described in detail in the Examples below.

[0171] The flexural strength of the molded article (according to JIS K7074 (1988)) is, for example, 250 MPa or more, or preferably 470 MPa or more.

[0172] The molded article has a flexural modulus (according to JIS K7074 (1988)) of, for example, 20 GPa or more, preferably 25 GPa or more, more preferably 30 GPa or more, and still more preferably 35 GPa or more.

[0173] The specific strength of the molded product is, for example, 180 MPa / (g / cm3 ) or more, preferably 250 MPa / (g / cm 3 ) or more, more preferably 300 MPa / (g / cm 3 )That's all.

[0174] The method for measuring the specific strength will be described in detail in the examples below.

[0175] The specific rigidity of the molded product is, for example, 20 (MPa) 1 / 3 / (g / cm 3 ) or more, preferably 22 (MPa) 1 / 3 / (g / cm 3 )That's all.

[0176] The method for measuring the specific strength will be described in detail in the examples below.

[0177] Such molded products can be widely used for building materials, housings, casting materials, machine parts, electronic and electrical parts, and various components for vehicles, ships, aircraft, etc. [Example]

[0178] Specific numerical values ​​of blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the corresponding upper limit values ​​(numeric values ​​defined as "not more than" or "less than") or lower limit values ​​(numeric values ​​defined as "not less than" or "exceeding") of blending ratios (content ratios), physical property values, parameters, etc. described in the above "Description of the Invention." Furthermore, unless otherwise specified in the following description, "parts" and "%" are based on mass. 1.Ingredient details Benzyl methacrylate: Trade name "Light Ester BZ", manufactured by Kyoeisha Chemical Co., Ltd. Polyvinyl acetate: Product name "VINAPAS C501", manufactured by Wacker Polymer Systems Saturated polyester: Trade name "Vylon (registered trademark) 550", manufactured by Toyobo Co., Ltd. Styrene-based thermoplastic elastomer: trade name "Kraton (registered trademark) G1701", styrene-ethylene / propylene-styrene-block copolymer, manufactured by Kraton Polymerization inhibitor: parabenzoquinone Polymerization initiator: trade name "Perbutyl (registered trademark) Z", manufactured by NOF Corporation Wetting and dispersing agent: Product name "BYK-W996", manufactured by BYK-Chemie GmbH Anti-separation agent: product name "BYK-W972", manufactured by BYK-Chemie GmbH Release agent: zinc stearate Calcium carbonate: Product name "NS#400", manufactured by Nitto Funka Kogyo Co., Ltd., average particle size 1.7 μm (catalog value) Milled carbon fiber: Product name "DonaCarbo Milled S-241", manufactured by Osaka Gas Chemicals Co., Ltd. Glass balloons: Product name: Glass Bubbles Filler K-37, manufactured by Sumitomo 3M, true density 0.37 g / cm 3 , pressure resistance 21MPa (catalog value) MgO: Kyowa Mag #100, manufactured by Kyowa Chemical Industry Co., Ltd. MDI: Product name "Cosmonate PH", manufactured by Mitsui Chemicals SKC Polyurethanes Carbon fiber 6K: 6000 carbon fiber bundles (unrefined), product name "TR50S 6L", manufactured by Mitsubishi Chemical Corporation Carbon fiber 12K: A bundle of carbon fibers with 12,000 strands (product name "T700-SC 12K", manufactured by Toray Industries, Inc.) Carbon fiber 24K: A fiber bundle of carbon fiber with 24,000 strands (product name "TC-35R 24K", manufactured by Formosa Plastics) Carbon fiber 48K: A fiber bundle of 48,000 carbon fibers (trade name "Panex35", manufactured by Zolteck) Carbon fiber 60K: A fiber bundle of carbon fiber with 60,000 strands (product name "TRH60M", manufactured by Mitsubishi Chemical Corporation) 2. Preparation of Vinyl Esters Synthesis Example 1 Into a reaction vessel (flask) equipped with a stirrer, a reflux condenser, and a gas inlet tube, 1,850 g of bisphenol A type epoxy resin (epoxy equivalent: 185), 2.0 g of hydroquinone as a polymerization inhibitor, 2.0 g of triethylbenzylammonium chloride as a catalyst, and 882 g of methacrylic acid were added, and the mixture was reacted at 110°C for 8 hours while blowing in air, to obtain an unmodified vinyl ester resin with an acid value of 7.0 mgKOH / g.

[0179] Synthesis Example 2 An unmodified vinyl ester resin was obtained in the same manner as in Synthesis Example 1, and then 490 g of maleic anhydride was added and reacted at 80° C. for 2 hours to obtain an acid-modified vinyl ester resin with an acid value of 94.1 mgKOH / g.

[0180] Synthesis Example 3 A reaction vessel (flask) equipped with a stirrer, reflux condenser, and gas inlet tube was charged with 1850 g of bisphenol A epoxy resin (epoxy equivalent weight 185), 210 g of bisphenol A, and 0.4 g of triethylbenzylammonium chloride as a catalyst. The mixture was reacted at 150°C for 5 hours while blowing in nitrogen to obtain an epoxy resin (bisphenol A-modified bisphenol A epoxy resin) with an epoxy equivalent weight of 252. After cooling to 120°C, 2.0 g of hydroquinone as a polymerization inhibitor, 2.0 g of triethylbenzylammonium chloride as a catalyst, and 719 g of methacrylic acid were added. The mixture was reacted at 110°C for 8 hours while blowing in air to obtain an unmodified vinyl ester resin with an acid value of 7.0 mgKOH / g.

[0181] Synthesis Example 4 An unmodified vinyl ester resin was obtained in the same manner as in Synthesis Example 3, and then 400 g of maleic anhydride was added and reacted at 80° C. for 2 hours to obtain an acid-modified vinyl ester resin with an acid value of 79.0 mgKOH / g.

[0182] Synthesis Examples 5, 7 and 9 An unmodified vinyl ester resin was obtained in the same manner as in Synthesis Example 3, except that the compounding recipe was changed according to Table 1.

[0183] In Synthesis Example 5, the epoxy equivalent of the bisphenol A-type epoxy resin modified with bisphenol A was 400.

[0184] In Synthesis Example 7, the epoxy equivalent of the bisphenol A-type epoxy resin modified with bisphenol A was 467.

[0185] In Synthesis Example 9, the epoxy equivalent of the bisphenol A-type epoxy resin modified with bisphenol A was 522.

[0186] Synthesis Examples 6, 8, and 10 An acid-modified vinyl ester resin was obtained in the same manner as in Synthesis Example 4, except that the compounding formulation was changed according to Table 1.

[0187] In Synthesis Example 6, the epoxy equivalent of the bisphenol A-type epoxy resin modified with bisphenol A was 400.

[0188] In Synthesis Example 8, the epoxy equivalent of the bisphenol A-type epoxy resin modified with bisphenol A was 467.

[0189] In Synthesis Example 10, the epoxy equivalent of the bisphenol A-type epoxy resin modified with bisphenol A was 522. 3. Manufacturing of molding materials Example 1 (Preparation of carbon fiber bundles) Carbon fiber 24K as a raw material for carbon fiber bundles (carbon fiber bundles before defibration) was cut into 1 inch pieces using a rotary cutter, and then defibrated using the defibration device described in JP 2019-065405 A.

[0190] The defibration conditions were as follows: the rotation speed of the rotating shaft in the upper defibration mechanism was 1500 rpm, the rotation speed of the rotating shaft in the middle defibration mechanism was 1500 rpm, and the rotation speed of the rotating shaft in the lower defibration mechanism was 1500 rpm. (Preparation of molding material) Each component was uniformly mixed according to the formulations in Tables 2 to 5 to obtain a resin composition. A thickener was added to the obtained resin composition (paste), and the mixture was stirred for 3 minutes. The mixture was then immediately fed to an SMC impregnation machine (Tsukishima Kikai Co., Ltd.), and carbon fiber 24K (defibrated) was added and thoroughly impregnated. The mixture was then aged for 48 hours to obtain a sheet-shaped molding material.

[0191] In Tables 2 to 5, the blending ratios of components other than the carbon fiber bundles are shown in parts by mass (parts), and the blending ratio of the carbon fiber bundles is shown as a mass ratio (mass%) to the total amount of the resin composition and the carbon fiber bundles.

[0192] Example 3, Example 5, Example 7, Example 8, Example 9, Example 12 and and examples 15. Example 16 Example 32, Comparative Example 1 13 (Preparation of carbon fiber bundles) The fiber bundles of carbon fibers before defibration were defibrated in the same manner as in Example 1, except that the defibration conditions shown in Tables 2 to 5 were followed. (Preparation of molding material) A sheet-shaped molding material was obtained in the same manner as in Example 1, except that the formulations in Tables 2 to 5 were used. 4. Evaluation (Storage stability) Each vinyl ester of each synthesis example was dissolved in styrene to prepare a 40% by mass styrene solution. The styrene solution was then allowed to stand at 25°C for 48 hours, after which the state of the styrene solution was visually inspected. The results are shown in Table 1. (heat deflection temperature) Each vinyl ester of each synthesis example was dissolved in styrene to prepare a 40% by weight styrene solution. Next, 0.5 parts by weight of cobalt octenoate (metal content 8%) and 1 part by weight of Kayamec M (manufactured by Kayaku Akzo Co., Ltd.) were added to 100 parts by weight of each styrene solution and mixed. Cast plates of the cured resin were prepared according to JIS K6919 (1992), and their deflection temperatures under load were measured according to JIS K6911 (1995). The results are shown in Table 1. (median and standard deviation) One hundred defibrated carbon fiber bundles were randomly extracted from the defibrated carbon fiber bundles used in each Example and Comparative Example, and the mass (m) of each extracted carbon fiber bundle and the fiber length (l) of each carbon fiber bundle were measured. From the obtained mass (m) and fiber length (l), the number of bundled fibers (n) of the defibrated carbon fiber bundle was calculated based on the following formula (10), and the median and standard deviation of this number of bundled fibers were calculated. n = (m × N × 1000) / (M × l) (10) (In the formula, n represents the number of fibers (K) in the carbon fiber bundle after defibration, m represents the mass (mg) of the carbon fiber bundle after defibration, N represents the number of fibers (K) in the carbon fiber bundle before defibration, M represents the fiber weight (g / 1000m) of the carbon fiber bundle before defibration, and 1 represents the fiber length (mm) of the carbon fiber bundle after defibration.) The results are shown in Tables 2 to 5. (bulk density) 50 g of the fiber bundle of the defibrated carbon fiber used in each Example and Comparative Example was placed in a 1 L measuring cylinder. The measuring cylinder was then shaken 100 times or more, and the graduations on the measuring cylinder were measured. Then, the bulk density was calculated according to the following formula (11). As a result, are shown in Tables 2 to 5. Bulk density = (mass of carbon fiber bundle (g)) / (reading value of measuring cylinder (mL)) (11) (Fluff) The carbon fiber bundles used in each example and comparative example were cut using the defibrating device described in JP 2019-065405 A, and the ends and sides of the cut carbon fiber bundles were visually observed, and the fluff was evaluated according to the following criteria. The results are shown in Tables 2 to 5. ◯: No fluffing was observed. △: A small amount of fluff was observed. ×: A lot of fluff was observed. (Viscosity of Resin Composition) The viscosity of the resin composition (paste) of each example and each comparative example at 25° C. was measured in accordance with JIS K6901 (2008). The results are shown in Tables 2 to 5. (impregnation) The molding material of each Example and Comparative Example was cut in the width direction, and the cross section was visually observed. The impregnation ability was evaluated according to the following criteria. The results are shown in Tables 2 to 5. Good: No carbon fiber bundles to which resin components were not attached were observed near the center of the thickness of the molding material. ×: Fiber bundles of carbon fibers to which no resin component was attached were observed near the center of the thickness of the molding material. (Seat handling) Two sheets of 200 x 200 mm molding material were cut out from the molding material of each Example and Comparative Example, and these were stacked and stuck together by hand and pressed tightly together, and then the two sheets were peeled off by hand.

[0193] In the above evaluation, the handleability of the sheet was evaluated according to the following criteria. The results are shown in Tables 2 to 5. ◯: When the laminated sheets were peeled off, they peeled off cleanly. △: The laminated sheets could be peeled off, but part of the sheet was stuck to the other sheet. ×: The laminated sheets could not be peeled off. (Fillability) A molding material measuring 106 mm x 106 mm was cut out from the molding material of each Example and Comparative Example, and 12 sheets of this molding material with a sheet thickness of 1 mm or 6 sheets of this molding material with a sheet thickness of 2 mm were stacked together, placed in the center of a 300 mm x 300 mm flat plate molding mold, and heated and pressurized for 5 minutes at 140°C and 5 MPa.

[0194] As a result, a molded product (molded plate) measuring 300 mm x 300 mm x approximately 1.5 mm was obtained.

[0195] In the above molding, the filling property of the molding material into the mold was evaluated according to the following criteria. The results are shown in Tables 2 to 5. 〇: Unfilled area is 0mm 2 It was. △: Unfilled area is 0mm 2 Excess 200mm 2 It was less than. ×: Unfilled area is 200mm 2 That was all. (exterior) A 210 mm x 210 mm molding material was cut out from the molding material of each Example and Comparative Example, and eight sheets of this were stacked in the case of molding material with a sheet thickness of 1 mm, or four sheets in the case of molding material with a sheet thickness of 2 mm, and placed in the center of a 300 mm x 300 mm flat plate molding mold.Then, heating and pressurizing were performed for 5 minutes under conditions of 140°C and 10 MPa.

[0196] As a result, a molded product (molded plate) measuring 300 mm x 300 mm x approximately 4 mm thick was obtained.

[0197] The surface condition of the obtained molded article was visually inspected and the appearance was evaluated according to the following criteria. The results are shown in Tables 2 to 5. ◯: No cracks, blisters or scratches were observed. x: Any of cracks, swelling and fading was observed. (smoothness) The molding materials of each Example and Comparative Example were subjected to heat compression molding using a 300 x 300 mm flat mold to form a 4 mm thick plate-like molded product. Molding was carried out under the following conditions: mold temperature: 145°C on the product surface, 130°C on the back surface, molding pressure: 10 MPa, and mold retention time: 5 minutes. Two straight-tube fluorescent lamps were projected onto the surface of the obtained plate-like molded product from a position 1.5 m above the surface, and the projected image was visually observed to evaluate the surface smoothness of the molded product. Surface smoothness was evaluated according to the following criteria. The results are shown in Tables 2 to 5. ○: The projected image had high linearity and parallelism. △: "Waviness" and distortion were observed in the projected image. ×: A large "waviness" was observed in the projected image, and the distortion was large. (Warpage) For each Example and Comparative Example, the molded article obtained in the above-mentioned filling property evaluation was removed from the mold and then left at 25°C for 24 hours. This molded article was placed on a precision surface plate specified in JIS B7513 (1992), and the gap between each side of the molded article and the precision surface plate was measured. Warpage was evaluated according to the following criteria. The results are shown in Tables 2 to 5. ○: No gaps were found. △: A gap exceeding 0 mm and less than 10 mm was observed. ×: A gap of 10 mm or more was observed. (density) For each of the Examples and Comparative Examples, the density of the molded articles obtained in the above appearance evaluation was determined by Archimedes' method using water at 25° C. The results are shown in Tables 2 to 5. (Flexural properties (flexural strength and flexural modulus)) For each example and each comparative example, a bending test was carried out in accordance with JIS K7074 (1988) using the molded articles obtained in the above appearance evaluation to measure the bending strength and bending modulus. The results are shown in Tables 2 to 5. (specific strength) From the measurement results of bending strength and density, the specific strength was calculated by the following formula (12).

[0198] Specific strength = (flexural strength) / (density) (12) The results are shown in Tables 2 to 5. (specific stiffness) The specific rigidity was calculated from the measurement results of the flexural modulus and density using the following formula (13). The results are shown in Tables 2 to 5.

[0199] Specific stiffness = (flexural modulus) 1 / 3 / (density)(13) 5. Discussion Example 1 , Example 3, Example 5, Example 7, Example 8, Example 9, Example 12 and Example 15, Comparative Examples 1 to 4 and Comparative Examples 7 to 13 Figure 2 shows the relationship between the median X and standard deviation Y in

[0200] In this case, it was found that a molding material that has excellent impregnation of the carbon fiber bundles with the resin component and excellent filling ability into a mold is one in which the median X and the standard deviation Y of the carbon fiber bundles are determined by the relational expressions (Y>0.5X, Y<0.5X+4000, X>2000, X<8000) in FIG. 2 (the shaded portion in FIG. 2).

[0201] In detail, Example 1 included in the above range , Example 3, Example 5, Example 7, Example 8, Example 9, Example 12,Example 15 and Comparative Examples 7 to 13 Compared with Comparative Examples 1 to 4 which are not within the above range, the carbon fiber bundles are excellent in impregnation with the resin component and are excellent in filling properties into a mold.

[0202] [Table 1]

[0203] [Table 2]

[0204] [Table 3]

[0205] [Table 4]

[0206] [Table 5]

Claims

1. A resin composition including a resin component and a fiber bundle of carbon fibers, The bulk density of the carbon fiber bundle is 0.15 g / ml or more and 0.3 g / ml or less, A molding material characterized in that the median X and standard deviation Y of the carbon fiber bundle measured by the following test satisfy the relationships of the following formulas (1) to (4) (excluding X=4620 and Y=3120, X=4430 and Y=3210, X=6750 and Y=3660, and X=5890 and Y=3080). Y>0.5X (1) Y<0.5X+2000 (2) X>2000 (3) X<8000 (4) Test: A carbon fiber bundle is defibrated using a defibrator, 100 defibrated carbon fiber bundles are randomly extracted from the defibrated carbon fiber bundle, the mass (m) of each extracted carbon fiber bundle and the fiber length (l) of each carbon fiber bundle are measured, and the number of bundled fibers (n) of the defibrated carbon fiber bundle is calculated from the obtained mass (m) and fiber length (l) based on the following formula (5), and the median and standard deviation of these bundled fibers are calculated. n=(m×N×1000) / (M×l) (5) (In the formula, n represents the number of fibers (K) in the carbon fiber bundle after defibration, m represents the mass (mg) of the carbon fiber bundle after defibration, N represents the number of fibers (K) in the carbon fiber bundle before defibration, M represents the fiber weight (g / 1000 m) of the carbon fiber bundle before defibration, and 1 represents the fiber length (mm) of the carbon fiber bundle after defibration.)

2. the resin component comprises a reaction product of a vinyl ester and an acid anhydride; The molding material according to claim 1 , wherein the resin composition contains a thickener.

3. 3. The molding material according to claim 2, wherein the thickener is magnesium oxide.

4. 4. The molding material according to claim 2, wherein the acid anhydride is blended in an amount of 0.6 mol or more and 1.4 mol or less per 1 mol of the vinyl ester.

5. The vinyl ester is a reaction product of an epoxy resin and an unsaturated monobasic acid, The molding material according to any one of claims 2 to 4, characterized in that the epoxy equivalent of the epoxy resin is 200 or more and 500 or less.

6. The blending ratio of the carbon fiber bundles with respect to the total amount of the resin composition and the carbon fiber bundles is 40% by mass or more and 65% by mass or less. The molding material according to any one of claims 1 to 5, characterized in that

7. A molded article comprising a cured product of the molding material according to any one of claims 1 to 6.

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