WO2024134929A1 - シートモールディングコンパウンド、及び成形品 - Google Patents

シートモールディングコンパウンド、及び成形品 Download PDF

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WO2024134929A1
WO2024134929A1 PCT/JP2023/023075 JP2023023075W WO2024134929A1 WO 2024134929 A1 WO2024134929 A1 WO 2024134929A1 JP 2023023075 W JP2023023075 W JP 2023023075W WO 2024134929 A1 WO2024134929 A1 WO 2024134929A1
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roll
sheet molding
molding compound
compounds
compound
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French (fr)
Japanese (ja)
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一迅 人見
泰之 村中
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DIC Corp
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DIC Corp
Dainippon Ink and Chemicals Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material

Definitions

  • the present invention relates to a sheet molding compound that has high moldability regardless of the thickness of the molded product, and to molded products made from the compound.
  • Carbon fiber reinforced plastics which are thermosetting resins reinforced with carbon fibers, have attracted attention for their lightweight yet excellent heat resistance and mechanical strength, and their use is expanding in a variety of applications such as automobiles, aircraft, and industrial parts.
  • sheet molding compounds hereinafter sometimes abbreviated as "SMC” that use discontinuous fibers as the carbon fibers can be molded into more complex shapes than when continuous carbon fibers are used, and also have the advantages of high productivity and a wide range of design applications, such as the ability to reuse scraps and insert components made of different materials.
  • sheet molding compounds include those that use a curable composition containing an epoxy resin, its curing agent, and a polyisocyanate compound as the matrix resin (see, for example, Patent Document 1), and those that use a curable composition containing a vinyl ester resin as the matrix resin (see, for example, Patent Document 2).
  • One of the issues with these current sheet molding compounds is molding defects that occur when the molded product has a complex shape or is relatively thick or thin. In particular, with relatively thin molded products, there are issues such as the sheet molding compound not having enough fluidity to be molded into the desired shape, and the strength and homogeneity of the molded product decreasing.
  • the problem that this invention aims to solve is therefore to provide a sheet molding compound that has high moldability regardless of the thickness of the molded product, and a molded product made from the compound.
  • a sheet molding compound containing a curable composition and carbon fiber, with a carbon fiber content of 35 mass% or more and a surface roughness (Sdr) in the range of 0.006 to 0.30 has high moldability regardless of the thickness of the molded product, and thus completed the present invention.
  • the present invention relates to (I) a sheet molding compound that contains a curable composition and carbon fibers, has a carbon fiber content of 35 mass% or more, and has a surface roughness (Sdr) in the range of 0.006 to 0.30.
  • the present invention further relates to (II) the sheet molding compound described in (I) above, in which the air content of the curable composition is in the range of 0.1 to 2.5 volume percent.
  • the present invention further relates to (III) the sheet molding compound described in (I) or (II) above, in which the curable composition is an epoxy resin composition or a vinyl ester resin composition.
  • the present invention further relates to (IV) a molded article made from the sheet molding compound described in any one of (I) to (III).
  • the sheet molding compound of the present invention is lightweight, has high strength, and has high moldability, and can be used to produce various components with complex shapes, making it suitable for use as components for transport equipment such as automobiles, ships, aircraft, etc.
  • it is suitable for use as automobile exterior components such as automobile bonnets, fenders, under covers, trunk lids, pillars, side sills, etc.
  • automobile structural components such as floor panels, engine covers, fender supports, partitions, door inners, and floor tunnels. They are also suitable as components for wind turbines for wind power generation, robots, medical equipment, and the like.
  • the present invention provides a sheet molding compound that has high moldability regardless of the thickness of the molded product, and a molded product made from the same.
  • the sheet molding compound and molded product of the present invention can be suitably used for a variety of applications, such as the exteriors and structures of automobile parts, railway vehicle parts, aerospace equipment parts, ship parts, housing equipment parts, sports parts, light vehicle parts, construction and civil engineering parts, and office equipment.
  • FIG. 1 is a schematic diagram showing an example of a sheet molding compound manufacturing apparatus.
  • FIG. 2 is a schematic diagram of a crown roll.
  • FIG. 3 is a schematic diagram showing a case where each of the two adjacent rolls in FIG. 1 is a concave-convex roll.
  • FIG. 4 is a schematic diagram of a sheet molding compound pressing device.
  • the sheet molding compound of the present invention contains a curable composition and carbon fibers, has a carbon fiber content of 35 mass% or more, and has a surface roughness (Sdr) in the range of 0.006 to 0.30.
  • the surface roughness (Sdr) of the sheet molding compound is a value measured in accordance with ISO 25178.
  • the detailed measurement conditions for the surface roughness (Sdr) in the present invention are as described in the Examples.
  • the surface roughness (Sdr) is a parameter that indicates how much the developed area (surface area) of a defined area increases relative to the area of the defined area, and the surface roughness (Sdr) of a completely flat surface is 0.
  • the sheet molding compound of the present invention has a surface roughness (Sdr) in the range of 0.006 to 0.30, and therefore has high moldability regardless of the thickness of the molded product. If the surface roughness (Sdr) is less than 0.006, it is difficult to peel the film well. If the surface roughness (Sdr) exceeds 0.30, the heat conduction to the sheet molding compound during molding becomes poor, and good molding cannot be performed.
  • the thickness of the sheet molding compound of the present invention can be set as desired depending on the desired properties of the molded product and the application.
  • the sheet molding compound since it has high moldability regardless of the thickness of the molded product, it is preferably 1 mm or more, more preferably 1.2 mm or more, and particularly preferably 1.5 mm or more. It is also preferably 10 mm or less, more preferably 5 mm or less, and particularly preferably 4 mm or less.
  • the sheet molding compound of the present invention contains a curable composition and carbon fiber, and has a carbon fiber content of 35% by mass or more.
  • the carbon fiber content can be set arbitrarily depending on the desired properties of the molded product and the application, but it is more preferable that the carbon fiber content is 40% by mass or more, since this results in a molded product with higher strength. It is also preferable that the carbon fiber content is 80% by mass or less, and more preferably 70% by mass or less.
  • the carbon fibers used in the present invention are not particularly limited and a wide variety of fibers can be used.
  • one type of carbon fiber may be used alone, or two or more types may be used in combination.
  • the carbon fibers include polyacrylonitrile-based fibers, pitch-based fibers, and rayon-based fibers. Among these, polyacrylonitrile-based fibers are preferred because they can produce molded products with higher strength.
  • the length of the carbon fiber is not particularly limited and can be set as desired depending on the desired properties of the molded product and the application. Usually, carbon fiber cut to a length of 2.5 to 50 mm is used, but carbon fiber cut to a length of 5 to 40 mm is more preferable because it has high fluidity in the mold during molding and is excellent in moldability.
  • the number of filaments in the carbon fiber bundle is preferably 1,000 or more, and more preferably 5,000 or more, since this allows for excellent impregnation of the curable composition and results in a molded product with higher strength. Also, the number is preferably 60,000 or less, and more preferably 30,000 or less.
  • the curable composition used in the present invention is not particularly limited and can be selected as desired depending on the desired properties of the molded product, the application, etc. Among them, an epoxy resin composition or a vinyl ester resin composition is preferable because it can produce molded products with higher strength. Details of both resin compositions are described below.
  • the epoxy resin composition is a thermosetting resin composition containing an epoxy group-containing compound and a curing agent or curing accelerator.
  • the epoxy group-containing compound is not particularly limited in its specific structure, and a wide variety of compounds can be used as long as they have an epoxy group in their molecular structure. One type may be used alone, or two or more types may be used in combination. Among them, compounds having two or more epoxy groups in their molecular structure are preferred, as they result in an epoxy resin composition with excellent curing reaction.
  • the proportion of compounds having two or more epoxy groups in the molecular structure of the entire epoxy group-containing compounds is preferably 80% by mass or more, and particularly preferably 90% by mass or more.
  • Examples of the epoxy group-containing compound include diglycidyloxybenzene, diglycidyloxynaphthalene, biphenol-type epoxy resins, bisphenol-type epoxy resins, polyglycidyl ethers of aliphatic polyols, novolac-type epoxy resins, alicyclic epoxy resins, glycidylamine-type epoxy resins, heterocyclic epoxy resins, glycidyl ester-type epoxy resins, triphenolmethane-type epoxy resins, phenol or naphthol aralkyl-type epoxy resins, phenylene or naphthylene ether-type epoxy resins, oxolidone-modified epoxy resins, brominated epoxy resins thereof, and epoxy resins obtained by extending these epoxy group-containing compounds with an extender.
  • the biphenol-type epoxy resin may be, for example, a biphenol compound such as biphenol or tetramethylbiphenol, or one or more alkylene oxide adducts of these biphenol compounds that have been polyglycidyl etherified with epihalohydrin.
  • the bisphenol type epoxy resins include, for example, bisphenol compounds such as bisphenol A, bisphenol F, bisphenol S, bisphenol fluorene, and biscresol fluorene, and polyglycidyl ethers of one or more alkylene oxide adducts of these bisphenol compounds with epihalohydrin.
  • the polyglycidyl ether of the aliphatic polyol may be, for example, a polyglycidyl ether of one or more of various aliphatic polyol compounds or their alkylene oxide adducts with epihalohydrin.
  • Examples of the aliphatic polyol compound include ethylene glycol, propylene glycol, 1,3-propanediol, 2-methylpropanediol, 1,2,2-trimethyl-1,3-propanediol, 2,2-dimethyl-3-isopropyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1, Examples include aliphatic diol compounds such as 6-hexanediol, 1,4-bis(hydroxymethyl)cyclohexane, and 2,2,4-trimethyl-1,3-pentanediol; alicyclic diol compounds such as 2,2-bis(4-hydroxyphenyl)propane; and aliphatic polyol compounds with three or more functional
  • the novolac type epoxy resin may be, for example, a novolac resin made of one or more of various phenolic compounds such as phenol, dihydroxybenzene, cresol, xylenol, naphthol, dihydroxynaphthalene, bisphenol, biphenol, etc., which is polyglycidyl etherified with epihalohydrin.
  • Alicyclic epoxy resins include, for example, those obtained by hydrogenating the biphenol compounds or bisphenol compounds, and those obtained by polyglycidyl etherifying one or more of these alkylene oxide adducts with epihalohydrin, as well as 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, 1-epoxyethyl-3,4-epoxycyclohexane, etc.
  • Examples of the glycidylamine type epoxy resin include N,N-diglycidylaniline, triglycidylaminophenol, tetraglycidylxylenediamine, 4,4'-methylenebis[N,N-diglycidylaniline], etc.
  • heterocyclic epoxy resin examples include 1,3-diglycidyl-5,5-dimethylhydantoin and triglycidyl isocyanurate.
  • Examples of the glycidyl ester type epoxy resin include diglycidyl ester of phthalic acid, diglycidyl ester of tetrahydrophthalic acid, diglycidyl-p-oxybenzoic acid, and glycidyl ester of dimer acid.
  • extenders for epoxy resins include the various biphenol compounds and their hydrogenated products, the various bisphenol compounds and their hydrogenated products, dibasic acid compounds, and acid group-containing polyester resins.
  • the bisphenol type epoxy resin is preferred because it provides excellent strength and carbon fiber impregnation of the molded product, and a bisphenol type epoxy resin having an epoxy equivalent in the range of 160 to 260 g/equivalent is more preferred.
  • the proportion of the bisphenol type epoxy resin in the entire epoxy group-containing compound is preferably 40 mass% or more, more preferably 60 mass% or more, and particularly preferably 70 mass% or more. Furthermore, it is preferably 95 mass% or less, and more preferably 90 mass% or less.
  • polyglycidyl ethers of the aliphatic polyols are preferred, and polyglycidyl ethers of aliphatic polyols having 2 to 6 carbon atoms are more preferred.
  • the proportion of the bisphenol-type epoxy resin in the entire epoxy group-containing compound is preferably 5% by mass or more, and more preferably 10% by mass or more. Furthermore, it is preferably 50% by mass or less, and more preferably 35% by mass or less.
  • the mass ratio of the two (bisphenol-type epoxy resin)/(polyglycidyl ether of the aliphatic polyol) is preferably in the range of 60/40 to 95/5, and more preferably in the range of 70/30 to 85/15.
  • the curing agent or curing accelerator may be any of various compounds that are generally used as curing agents or curing accelerators for epoxy group-containing compounds, without any particular restrictions.
  • the curing agent or curing accelerator may be used alone or in combination of two or more types.
  • curing agent or curing accelerator examples include amine compounds, amide compounds, acid anhydrides, phenolic hydroxyl group-containing compounds, phosphorus compounds, imidazole compounds, imidazoline compounds, urea compounds, organic acid metal salts, Lewis acids, and amine complex salts.
  • the amine compounds include, for example, aliphatic amine compounds such as ethylenediamine, tetramethylethylenediamine, diethylenetriamine, hexamethylenediamine, triethylenetetramine, and guanidine derivatives; alicyclic and heterocyclic amine compounds such as piperidine, piperazine, isophoronediamine, and 1,8-diazabicyclo-[5.4.0]-undecene (DBU); aromatic amine compounds such as phenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, benzylmethylamine, dimethylbenzylamine, xylylenediamine, and pyridine; and boron trifluoride amine complexes.
  • aliphatic amine compounds such as ethylenediamine, tetramethylethylenediamine, diethylenetriamine, hexamethylenediamine, triethylenetetramine, and guanidine derivatives
  • Examples of the amide compound include dicyandiamide and polyamidoamine.
  • Examples of the polyamidoamine include those obtained by reacting an aliphatic dicarboxylic acid such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, or azelaic acid, or a carboxylic acid compound such as a fatty acid or dimer acid, with an aliphatic polyamine or a polyamine having a polyoxyalkylene chain.
  • Examples of the acid anhydride include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.
  • phenolic hydroxyl group-containing resin examples include various novolak resins, dicyclopentadiene-phenol addition type resins, phenol or naphthol aralkyl resins, triphenolmethane resins, phenol or naphthol aralkyl resins, phenylene or naphthylene ether resins, and aminotriazine-modified phenolic resins.
  • Examples of the phosphorus compound include alkyl phosphines such as ethylphosphine and butylphosphine, primary phosphines such as phenylphosphine, dialkyl phosphines such as dimethylphosphine and dipropylphosphine, secondary phosphines such as diphenylphosphine and methylethylphosphine, and tertiary phosphines such as trimethylphosphine, triethylphosphine, and triphenylphosphine.
  • alkyl phosphines such as ethylphosphine and butylphosphine
  • primary phosphines such as phenylphosphine
  • dialkyl phosphines such as dimethylphosphine and dipropylphosphine
  • secondary phosphines such as diphenylphosphine and methylethy
  • the imidazole compound is, for example, imidazole, 1-methylimidazole, 2-methylimidazole, 3-methylimidazole, 4-methylimidazole, 5-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 3-ethylimidazole, 4-ethylimidazole, 5-ethylimidazole, 1-n-propylimidazole, 2-n-propylimidazole, 1-isopropylimidazole, 2- Isopropylimidazole, 1-n-butylimidazole, 2-n-butylimidazole, 1-isobutylimidazole, 2-isobutylimidazole, 2-undecyl-1H-imidazole, 2-heptadecyl-1H-imidazole, 1,2-dimethylimidazole, 1,3-dimethylimidazole, 2,4-dimethylimidazole, 2-e
  • imidazoline compound examples include 2-methylimidazoline and 2-phenylimidazoline.
  • urea compound examples include p-chlorophenyl-N,N-dimethylurea, 3-phenyl-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-N,N-dimethylurea, N-(3-chloro-4-methylphenyl)-N',N'-dimethylurea, and 4,4'-methylenebisphenyldimethylurea.
  • amine compounds, amide compounds, imidazole compounds, and urea compounds are preferred because they cure quickly and produce cured products with excellent strength.
  • the amount of the curing agent or curing accelerator in the epoxy resin composition is preferably in a ratio of 0.5 to 1.2 moles of functional groups or active hydrogen in the curing agent per mole of epoxy group in the epoxy group-containing compound.
  • a phosphorus compound, an imidazole compound, an imidazoline compound, a urea-based compound, or the like it is preferably in a ratio of 0.5 to 20 parts by mass per 100 parts by mass of the epoxy group-containing compound.
  • the epoxy resin composition may contain other components in addition to the epoxy group-containing compound and the curing agent or curing accelerator.
  • other components include curable compounds other than the epoxy group-containing compound, curing agent, or curing accelerator, curing catalysts, water absorbents, thermoplastic resins, inorganic fillers, low shrinkage agents, mold release agents, thickeners, viscosity reducers, pigments, antioxidants, plasticizers, flame retardants, antibacterial agents, UV stabilizers, reinforcing materials, etc.
  • curable compounds other than the epoxy group-containing compound, curing agent, or curing accelerator curing catalysts, water absorbents, thermoplastic resins, inorganic fillers, low shrinkage agents, mold release agents, thickeners, viscosity reducers, pigments, antioxidants, plasticizers, flame retardants, antibacterial agents, UV stabilizers, reinforcing materials, etc.
  • the total mass of the epoxy group-containing compound, the curing agent or curing accelerator, the polyhydroxy compound, and the polyisocyanate compound in the epoxy resin composition is preferably 80 mass% or more, and particularly preferably 90 mass% or more.
  • the polyhydroxy compound may be of any type, and may be of any structure, so long as it has a plurality of hydroxyl groups in its molecular structure.
  • the polyhydroxy compound may be used alone or in combination of two or more types.
  • polyhydroxy compounds having epoxy groups are treated as epoxy group-containing compounds.
  • polyhydroxy compounds examples include aliphatic polyol compounds, dihydroxybenzenes, dihydroxynaphthalenes, trihydroxybenzenes, trihydroxynaphthalenes, triphenol alkanes, biphenol compounds, bisphenol compounds, alicyclic polyol compounds, novolac resins, phenol or naphthol aralkyl resins, phenylene or naphthylene ether resins, and alkylene oxide adducts thereof.
  • the aliphatic polyol compound may be, for example, ethylene glycol, propylene glycol, 1,3-propanediol, 2-methylpropanediol, 1,2,2-trimethyl-1,3-propanediol, 2,2-dimethyl-3-isopropyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol,
  • Examples include aliphatic diol compounds such as 1,6-hexanediol, 1,4-bis(hydroxymethyl)cyclohexane, and 2,2,4-trimethyl-1,3-pentanediol; alicyclic diol compounds such as 2,2-bis(4-hydroxyphenyl)propane; and aliphatic polyol
  • biphenol compound examples include biphenol, tetramethylbiphenol, etc.
  • bisphenol compounds examples include bisphenol A, bisphenol F, bisphenol S, bisphenol fluorene, and biscresol fluorene.
  • alicyclic polyol compounds examples include cyclohexanediol and hydrogenated biphenol compounds and bisphenol compounds.
  • the novolac type resin may be, for example, a novolac resin made of one or more of various phenolic compounds, such as phenol, dihydroxybenzene, cresol, xylenol, naphthol, dihydroxynaphthalene, bisphenol, and biphenol.
  • a polyhydroxy compound having a hydroxyl equivalent in the range of 125 to 600 g/equivalent since this will result in a sheet molding compound with excellent handling properties such as peelability from the carrier film, and the ratio of polyhydroxy compounds having a hydroxyl equivalent in the range of 125 to 600 g/equivalent to the total polyhydroxy compounds is more preferably 70 mass% or more, and particularly preferably 80 mass% or more.
  • the polyhydroxy compound is preferably one having a (poly)alkylene oxide structure in its molecular structure, more preferably an alkylene oxide adduct of the aliphatic polyol compound or the bisphenol compound, and more preferably an aliphatic polyol compound having 2 to 6 carbon atoms. Furthermore, it is more preferable that the hydroxyl equivalent is in the range of 150 to 400 g/equivalent.
  • the amount of the polyhydroxy compound is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more, per 100 parts by mass of the epoxy group-containing compound, in order to provide a sheet molding compound having excellent handleability, such as strength of the molded product and ease of peeling from the carrier film.
  • the amount of the polyhydroxy compound is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more, per 100 parts by mass of the epoxy group-containing compound.
  • the amount is preferably 50 parts by mass or less, and more preferably 30 parts by mass or less.
  • the polyisocyanate compound may have any of a wide variety of structures, as long as it has a plurality of isocyanate groups in its molecular structure.
  • the polyisocyanate compound may be used alone or in combination of two or more. Specific examples include aliphatic diisocyanate compounds such as butane diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and dimer acid diisocyanate; alicyclic diisocyanate compounds such as norbornane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and hydrogenated diphenylmethane diisocyanate; toluene diisocyanate, and xylylene diisocyanate.
  • aliphatic diisocyanate compounds such as butane diisocyanate
  • aromatic diisocyanate compounds such as tetramethylxylylene diisocyanate, tolidine diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, and polymethylene polyphenyl polyisocyanate; modified products of these isocyanate compounds, such as isocyanurate modified products, biuret modified products, allophanate modified products, carbodiimide modified products, and urethane imine modified products, as well as polyol modified products modified with a polyol having a number average molecular weight of 1,000 or less, such as diethylene glycol or dipropylene glycol.
  • aromatic polyisocyanate compounds or various modified products thereof are preferred because they provide sheet molding compounds with excellent handling properties, such as peelability from the carrier film.
  • the isocyanate group content is preferably 15% by mass or more, and more preferably 20% by mass or more. It is also preferred that the isocyanate group content is 40% by mass or less.
  • the amount of the polyisocyanate compound added is preferably such that the number of moles of isocyanate groups in the polyisocyanate compound per mole of hydroxyl groups in the polyhydroxy compound is 0.5 or more, more preferably 0.8 or more, in order to produce a sheet molding compound with excellent handling properties, such as peelability from the carrier film. It is also preferable that the number of moles of isocyanate groups in the polyisocyanate compound is 3.0 or less, more preferably 1.5 or less, and particularly preferably 1.2 or less.
  • a urethane catalyst or a water absorbent may be added as necessary.
  • the urethane catalyst may be used alone or in combination of two or more.
  • the urethane catalyst include amine compounds such as triethylamine, dibutylamine, triethylenediamine, and pyridine; phosphorus compounds such as triphenylphosphine and triethylphosphine; organic tin compounds such as dibutyltin dilaurate, octyltin trilaurate, octyltin diacetate, dibutyltin diacetate, and tin octylate; organic zinc compounds such as zinc amine, zinc carboxylate, zinc stearate, and zinc octylate; organic bismuth compounds such as bismuth carboxylate; organic zirconium compounds such as zirconium acetylacetonate and zirconium t
  • the amount added is preferably in the range of 0.002 to 1 mass % relative to the total mass of the epoxy group-containing compound, the curing agent or curing accelerator, the polyhydroxy compound, and the polyisocyanate compound, and more preferably in the range of 0.01 to 0.8 mass %.
  • the water absorbing agent may be used alone or in combination of two or more kinds.
  • water absorbing agents include silica gel, activated alumina, and molecular sieves. Among these, molecular sieves are preferred because of their excellent water absorption efficiency.
  • the pore size is preferably in the range of 0.1 to 0.5 nm, and more preferably in the range of 0.2 to 0.4 nm.
  • the particle size is preferably 50 um or less, and more preferably 10 um or less.
  • the amount of the water absorbing agent added is preferably in the range of 0.1 to 5 mass% based on the total mass of the epoxy group-containing compound, the curing agent or curing accelerator, the polyhydroxy compound, and the polyisocyanate compound.
  • the epoxy resin composition has excellent carbon fiber impregnation properties, so the viscosity at 25°C is preferably 100 mPa ⁇ s or more, and more preferably 300 mPa ⁇ s or more. It is also preferably 10,000 mPa ⁇ s or less, and more preferably 6,000 mPa ⁇ s or less. In the present invention, the viscosity of the curable composition is measured within 10 minutes after all the ingredients of the curable composition are mixed.
  • the vinyl ester resin composition is a thermosetting resin composition containing a vinyl ester resin.
  • vinyl ester resins include those that use an epoxy group-containing compound and (meth)acrylic acid as reaction raw materials.
  • One type of vinyl ester resin may be used alone, or two or more types may be used in combination.
  • (meth)acrylic acid refers to either or both of acrylic acid and methacrylic acid
  • (meth)acrylate refers to either or both of acrylate and methacrylate.
  • the epoxy group-containing compound that serves as the reaction raw material for the vinyl ester resin includes the various compounds exemplified above as those contained in the epoxy resin composition.
  • the bisphenol type epoxy resin or the epoxy resin obtained by elongating the bisphenol type epoxy resin with an elongating agent is preferred because it provides excellent strength and carbon fiber impregnation of the molded product.
  • the epoxy equivalent of the bisphenol type epoxy resin or the epoxy resin obtained by elongating the bisphenol type epoxy resin with an elongating agent is preferably 160 g/equivalent or more, more preferably 170 g/equivalent or more. It is also preferably 400 g/equivalent or less, more preferably 380 g/equivalent or less.
  • the reaction between the epoxy group-containing compound and (meth)acrylic acid can be carried out by heating at a temperature of about 60 to 140°C in the presence of any esterification catalyst. If necessary, a reaction solvent or a polymerization inhibitor may be added.
  • the reaction ratio of the epoxy group-containing compound and (meth)acrylic acid is preferably such that the molar ratio of the functional groups of both [carboxy group/epoxy group] is in the range of 0.6 to 1.1 in order to obtain a vinyl ester resin with an excellent balance of performance such as impregnation into hardened fibers and hardening properties.
  • multiple epoxy group-containing compounds may be (meth)acrylated together, or each may be (meth)acrylated separately and mixed.
  • the proportion of the vinyl ester resin made from the bisphenol-type epoxy resin or an epoxy resin obtained by elongating the bisphenol-type epoxy resin with an elongator as a reaction raw material in the entire vinyl ester resin is preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more.
  • the vinyl ester resin composition may contain other components in addition to the vinyl ester resin composition.
  • other components include polymerizable unsaturated group-containing compounds other than the vinyl ester resin, polyisocyanate compounds, curing catalysts, water absorbents, thermoplastic resins, inorganic fillers, low shrinkage agents, release agents, thickeners, viscosity reducers, pigments, antioxidants, plasticizers, flame retardants, antibacterial agents, UV stabilizers, reinforcing materials, etc. These other components are added as appropriate depending on the desired performance and applications of the sheet molding compound, and the amount of addition is also optional.
  • a polymerizable unsaturated group-containing compound other than the vinyl ester resin because it provides excellent strength and carbon fiber impregnation of the molded product.
  • the polymerizable unsaturated group-containing compound may be used alone or in combination of two or more types.
  • the ratio of the vinyl ester compound to the total of both is preferably 30% by mass or more, more preferably 40% by mass or more, and particularly preferably 50% by mass or more. It is also preferable that it is 85% by mass or less, and more preferably 70% by mass or less.
  • Examples of the polymerizable unsaturated group-containing compound include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, isotridecyl (meth)acrylate, n-stearyl (meth)acrylate, and ethylene glycol (meth)acrylate alkyl ether.
  • aliphatic mono(meth)acrylate compounds such as alkyl ether and propylene glycol (meth)acrylate alkyl ether
  • alicyclic mono(meth)acrylate compounds such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl mono(meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and dicyclopentanyl methacrylate
  • heterocycle-containing mono(meth)acrylate compounds such as glycidyl (meth)acrylate and tetrahydrofurfuryl acrylate
  • benzyl (meth)acrylate aromatic ring-containing mono(meth)acrylate compounds such as phenyl(meth)acrylate, phenylbenzyl(meth)acrylate, phenoxy(meth)acrylate, phenoxyethyl(meth)acrylate, phenoxyethoxyethyl(meth)acryl
  • aromatic ring-containing (meth)acrylate compounds are preferred, and aromatic ring-containing mono(meth)acrylates are more preferred, as they provide superior strength for molded articles and carbon fiber impregnation.
  • the vinyl ester resin composition preferably contains a polyisocyanate compound, since this results in a sheet molding compound with excellent handling properties, such as peelability from the carrier film.
  • a polyisocyanate compound may be used alone, or two or more types may be used in combination.
  • the amount of polyisocyanate compound added is preferably 5% by mass or more, and more preferably 10% by mass or more, based on the total mass of the vinyl ester resin and the polymerizable unsaturated group-containing compound. Also, it is preferably 40% by mass or less, and more preferably 30% by mass or less.
  • the polyisocyanate compound may be any of the various compounds exemplified as those that may be contained in the epoxy resin composition. Among these, aromatic polyisocyanate compounds or various modified products thereof are preferred, as they provide a sheet molding compound with excellent handling properties, such as peelability from the carrier film. Furthermore, the isocyanate group content is preferably 15% by mass or more, and more preferably 20% by mass or more. It is also preferred that the isocyanate group content is 40% by mass or less.
  • the vinyl ester resin composition may contain a polymerization initiator. Any common polymerization initiator may be used without any particular restrictions, but organic peroxides are particularly preferred. Examples of organic peroxides include diacyl peroxide compounds, peroxyester compounds, hydroperoxide compounds, ketone peroxide compounds, alkyl perester compounds, percarbonate compounds, and peroxyketals. These polymerization initiators may be used alone or in combination of two or more. From the viewpoint of the balance between storage stability and curability, the amount of polymerization initiator added is preferably in the range of 0.3 to 3 mass% based on the total mass of the vinyl ester resin and the polymerizable unsaturated group-containing compound.
  • the vinyl ester resin composition may contain a polymerization initiator.
  • polymerization inhibitors include hydroquinone, trimethylhydroquinone, p-t-butylcatechol, t-butylhydroquinone, toluhydroquinone, p-benzoquinone, naphthoquinone, hydroquinone monomethyl ether, phenothiazine, copper naphthenate, copper chloride, and the like. These may be used alone or in combination of two or more.
  • the amount of polymerization inhibitor added is preferably in the range of 0.01 to 3 mass% based on the total mass of the vinyl ester resin and the polymerizable unsaturated group-containing compound.
  • the vinyl ester resin composition has excellent carbon fiber impregnation properties, so the viscosity at 25°C is preferably 100 mPa ⁇ s or more, and more preferably 300 mPa ⁇ s or more. It is also preferably 10,000 mPa ⁇ s or less, and more preferably 6,000 mPa ⁇ s or less. In the present invention, the viscosity of the curable composition is measured within 10 minutes after all the ingredients of the curable composition are mixed.
  • the air content of the curable composition is preferably 0.1 vol.% or more, more preferably 0.5 vol.% or more, and particularly preferably 0.7 vol.% or more, since this makes it easy to control the surface roughness (Sdr) of the sheet molding compound within the above range. Also, it is preferably 2.5 vol.% or less, and more preferably 1.5 vol.% or less.
  • the air content of the curable composition is a value calculated by the method described in the Examples.
  • the air content of the curable composition can be adjusted by degassing in a vacuum state, using a centrifugal defoamer, blowing in air or nitrogen, or incorporating air by stirring.
  • the air content of the curable composition is measured by mixing all the components contained in the curable composition and then adjusting the air content by any method.
  • the air content of both the curable composition mixed with the components other than the curable composition and the component (polyisocyanate compound, etc.) is measured, and the air content is calculated by adding up the product of the measured value and the blending mass ratio of both.
  • the method for producing the sheet molding compound of the present invention is not particularly limited, and it can be produced by a general method. Specifically, it can be produced by a method including some or all of the following steps: uniformly mixing the curable composition using a mixer such as a mixer, roll mill, kneader, extruder, etc.; applying the curable composition to a carrier film in a uniform thickness; scattering carbon fibers on the resin surface of the obtained carrier film with resin; sandwiching reinforcing fibers with the resin surface of another carrier film with resin; applying pressure with an impregnation roll or impregnation belt to impregnate the carbon fibers with the curable composition (hereinafter referred to as the "impregnation step"); winding the sheet obtained by the impregnation step into a roll or folding it zigzag; and aging at room temperature or under a temperature condition of 20 to 60°C.
  • a mixer such as a mixer, roll mill, kneader, extruder, etc
  • the impregnation roll or impregnation belt used in the impregnation step is not particularly limited and can be of various shapes, but it is preferable to use one or more crown rolls.
  • a crown roll is used for at least one of them, the gas present between the first carrier film and the second carrier film is pushed out toward both ends of the laminate (in other words, in a direction approximately perpendicular to the conveying direction of the laminate), and degassing from the laminate is performed with high accuracy.
  • the surface roughness (Sdr) of the obtained sheet molding compound can be easily adjusted to a range of 0.006 to 0.30, and the air content can also be easily adjusted.
  • the crown roll can also be used in a step subsequent to the impregnation step, for example, before aging.
  • FIG. 1 An example of a sheet molding compound manufacturing apparatus used in the present invention is shown in Figure 1.
  • Figure 1 is merely an example of a manufacturing apparatus, and the manufacturing method of the sheet molding compound of the present invention is not limited to the use of this apparatus.
  • the manufacturing apparatus 1 shown in Figure 1 has a first delivery roll 2, a first application section 3, a carbon fiber supply section 4, a second delivery roll 5, a second application section 6, a conveying section 7, a pressure section 8, and a winding roll 9.
  • the flow direction of the sheet molding compound from the first delivery roll 2 to the winding roll 9 in the manufacturing apparatus 1 is referred to as the conveying direction MD.
  • the first delivery roll 2 is a roll around which the first carrier film F1 is wound, and is located at the most upstream of the manufacturing device 1.
  • the first carrier film F1 is one of the components used in manufacturing SMC, and is pulled out from the conveying section 7.
  • the first carrier film F1 is used as one of the support members for conveying the SMC.
  • the first carrier film F1 may have a single layer structure or a laminated structure. When the first carrier film F1 has a laminated structure, the first carrier film F1 may be a laminate film.
  • the first carrier film F1 is, for example, a polyethylene film, a polypropylene film, a laminated film of polyethylene and polypropylene, polyethylene terephthalate, a nylon film, etc.
  • the first coating section 3 is a section that coats the first curable composition 3a onto the first carrier film F1 during transport, and is located downstream of the first delivery roll 2.
  • a film-like first curable composition (not shown) is provided on the first carrier film F1 that has passed through the first coating section 3.
  • the amount of the first curable composition 3a applied by the first coating section 3 is appropriately adjusted according to the desired thickness and carbon fiber content of the sheet molding compound. In the present invention, the amount is preferably in the range of 0.3 kg/m 2 to 2.0 kg/m 2 , since this makes it easy to adjust the thickness and carbon fiber content of the sheet molding compound to the preferred values described above.
  • the carbon fiber supplying section 4 is a section that supplies cut pieces CC of carbon fiber RF onto the film-like first curable composition 3a to be applied. Therefore, the location where the cut pieces CC are supplied in the carbon fiber supplying section 4 is located downstream of the first application section 3.
  • the carbon fiber supplying section 4 has a pull-out roll 11 that pulls out a bundle of carbon fiber RF (e.g., roving), and a cutting device 12 that cuts the carbon fiber RF.
  • the cutting device 12 produces a plurality of cut pieces CC by cutting the carbon fiber RF to a predetermined dimension.
  • the carbon fiber supply section 4 is located above the first delivery roll 2 and the first application section 3. This allows the cut pieces CC to be spread onto the film-like first curable composition 3a by utilizing gravity. In this case, the cut pieces CC can fall uniformly onto the first curable composition 3a without orientation, which may reduce the likelihood of the sheet molding compound becoming brittle in a specific direction.
  • the second delivery roll 5 is a roll on which the second carrier film F2 is wound.
  • the second carrier film F2 is another member for manufacturing the sheet molding compound and functions as another support member for transporting the sheet molding compound.
  • the second carrier film F2 may have, for example, the same structure as the first carrier film F1.
  • the second coating section 6 is a section that coats the second curable composition 6a onto the second carrier film F2 during transport, and is located downstream of the second delivery roll 5.
  • a film-like second curable composition (not shown) is provided on the second carrier film F2 that has passed through the second coating section 6.
  • the amount of the second curable composition 6a applied by the second coating section 6 is appropriately adjusted according to the desired thickness and carbon fiber content of the sheet molding compound. In the present invention, the amount is preferably in the range of 0.3 kg/m 2 to 2.0 kg/m 2 , since this makes it easy to adjust the thickness and carbon fiber content of the sheet molding compound to the preferred values described above.
  • the transport unit 7 is a device for transporting the first carrier film F1 and the like to the winding roll 9, and is located downstream of the first application unit 3 and the second application unit 6.
  • the transport unit 7 is, for example, a belt conveyor that transports at least the first carrier film F1, but is not limited to this. In this embodiment, the transport unit 7 transports not only the first carrier film F1, but also the second carrier film F2 to the winding roll 9.
  • the pressure unit 8 is a part that pressurizes the first carrier film F1 and the second carrier film F2 that sandwich the first curable composition 3a to which the cut pieces CC are supplied and the second curable composition 6a facing the first curable composition 3a, and is located downstream of the first application unit 3 and the second application unit 6.
  • the pressure unit 8 has a plurality of rolls included in the manufacturing device 1. These multiple rolls may include, for example, a smooth roll with a smooth surface and no change in diameter in the axial direction, an uneven roll with an uneven surface, a crown roll, etc.
  • the pressure unit 8 may also have a receiving roll that is a pair with the above roll. At least a part of the pressure unit 8 overlaps with the conveying unit 7 in the vertical direction. In FIG.
  • the sheet molding compound manufacturing device used in the present invention is not limited to this.
  • various roll configurations are possible, such as those with fewer or more rolls in the pressure section 8, or those without crown rolls.
  • the pair of receiving rolls 21 are members that receive the first carrier film F1 to which the first curable composition 3a is applied, and the second carrier film F2 to which the second curable composition 6a is applied.
  • the pair of receiving rolls 21 has a first smooth roll 21a that contacts the first carrier film F1, and a second smooth roll 21b that contacts the second carrier film F2.
  • a laminate S containing the first curable composition 3a, the second curable composition 6a, and reinforcing fiber RF is provided between the first carrier film F1 and the second carrier film F2 that have passed through the pair of receiving rolls 21.
  • the laminate S is a sheet-like member that will later become a sheet molding compound.
  • FIG. 2 is a schematic diagram of the crown roll.
  • the crown roll 22 is a member extending in the axial direction AD perpendicular to the conveying direction MD.
  • the outer diameter of the crown roll 22 is non-uniform in the axial direction AD, unlike the receiving roll 21, the smooth roll 27, and the smooth receiving rolls 30a to 30f.
  • the outer diameter of the crown roll 22 becomes smaller as it approaches both ends from the center of the crown roll 22 in the axial direction AD. Therefore, in the axial direction AD, the outer diameter OD1 (center diameter) of the center of the crown roll 22 is the largest, and the outer diameter OD2 (end diameter) of the end 22a of the crown roll 22 is the smallest.
  • the outer diameter OD1 is preferably in the range of 100 mm to 200 mm, since this makes it easy to handle as a manufacturing device.
  • the central part of the crown roll 22 in the axial direction AD may have a region where the outer diameter does not change (i.e., a region where no taper is provided, also referred to as a region where the outer diameter is uniform). In other words, a smooth roll region may be provided in the center of the crown roll 22.
  • the dimension of the above region along the axial direction AD is, for example, half or less of the dimension of the crown roll 22 along the axial direction AD.
  • the taper angle of the crown roll 22 is adjusted appropriately depending on the thickness of the sheet molding compound and the carbon fiber content, but since this makes it easy to adjust the surface roughness (Sdr) of the resulting sheet molding compound to a range of 0.006 to 0.30, it is preferably 0.1° or more, and more preferably 0.2° or more. It is also preferably 1.3° or less, and more preferably 0.8° or less.
  • This taper angle corresponds to a multiple of the gradient angle ⁇ of the crown roll 22 shown in Figure 2.
  • the dimension of the crown roll 22 along the axial direction AD is, for example, 1000 mm or more and 2000 mm or less.
  • the dimension may be 1100 mm or more, 1200 mm or more, 1300 mm or more, 1800 mm or less, 1600 mm or less, or 1500 mm or less.
  • the difference between the outer diameter OD1 and the outer diameter OD2 is, for example, 0.5 mm or more and 8 mm or less.
  • the material of the crown roll 22 is not particularly limited, but from the viewpoint of preventing damage to the laminate S, it is silicone, elastomer, nitrile rubber, urethane rubber, etc.
  • the hardness of the crown roll 22 measured in accordance with JIS K 6253-1997 is, for example, 40 or more and 55 or less.
  • a smooth receiving roll 30a is provided below the crown roll 22.
  • the smooth receiving roll 30a is a receiving member corresponding to the crown roll 22 and is spaced apart from the crown roll 22.
  • the dimensions of the smooth receiving roll 30a along the axial direction AD are approximately the same as those of the crown roll 22.
  • the material of the smooth receiving roll 30a is not particularly limited, and may be, for example, metal, alloy such as stainless steel, rubber, plastic, etc.
  • the outer diameter of the smooth receiving roll 30a is not particularly limited, and may be, for example, 50% to 90% of the outer diameter OD1 of the crown roll 22. In the following, the smooth receiving rolls 30a to 30f are assumed to have the same dimensions, but are not limited to this.
  • the gap between the crown roll 22 and the smooth receiving roll 30a is the area through which the laminate S sandwiched between the first carrier film F1 and the second carrier film F2 passes, and is substantially equivalent to the thickness of the sheet molding compound, for example. Therefore, when passing through the gap between the crown roll 22 and the smooth receiving roll 30a, at least a part of the laminate S is pressed by the crown roll 22 and the smooth receiving roll 30a.
  • the gap is the minimum gap between the crown roll 22 and the smooth receiving roll 30a.
  • the smooth receiving roll 30a is provided in the conveying section 7. Therefore, a belt is provided between the crown roll 22 and the smooth receiving roll 30a. Therefore, the minimum gap in this embodiment corresponds to the total thickness of the SMC, the first carrier film F1, the second carrier film F2, and the belt.
  • Each of the rolls 23 to 26 is a member that pressurizes the laminate S to promote the impregnation of the first curable composition 3a and the second curable composition 6a into the reinforcing fiber RF in the laminate S, and is located downstream of the crown roll 22.
  • Each of the rolls 23 to 26 is arranged in order along the conveying direction MD.
  • the rolls 23 to 26 are located on approximately the same plane. Here, “approximately” on the same plane means that the difference between the top and bottom is within ⁇ 10% of the maximum diameter of the rolls 23 to 26.
  • the material of the rolls 23 to 26 is not particularly limited, and may be, for example, metal, alloy such as stainless steel, rubber, plastic, etc.
  • Figure 3 is a schematic diagram of the case where two adjacent rolls 23, 24 in Figure 1 are each an uneven roll.
  • roll 23 (first uneven roll) and roll 24 (second uneven roll) adjacent to each other in the conveying direction MD are positioned in approximately the same plane and extend along the axial direction AD like the crown roll 22.
  • the dimensions of rolls 23, 24 along the axial direction AD are approximately the same as those of the crown roll 22, for example.
  • the surface 23a of the roll 23 is provided with a plurality of convex portions 23b (first convex portions) that are intermittently arranged along the axial direction AD.
  • the surface 24a of the roll 24 is provided with a plurality of convex portions 24b (second convex portions) that are intermittently arranged along the axial direction AD.
  • Each of the convex portions 23b, 24b is a portion that protrudes along the radial direction of the rolls 23, 24.
  • Each of the convex portions 23b, 24b has a ring shape when viewed from the axial direction AD, but is not limited to this.
  • the tips of the convex portions 23b, 24b may or may not be rounded.
  • the convex portions 23b, 24b may have a tapered shape.
  • the multiple convex portions 23b and the multiple convex portions 24b are alternately arranged. Therefore, in the axial direction AD, one of the multiple convex portions 24b can be arranged between two adjacent convex portions 23b among the multiple convex portions 23b. That is, the multiple convex portions 23b, 24b are arranged in a comb shape. This allows the convex portion 23b to contact one part of the laminate S, and the convex portion 24b to contact another part of the laminate S.
  • the roll 25 may have the same shape as the roll 23, and the roll 26 may have the same shape as the roll 24. In this case, in the axial direction AD, the multiple convex portions provided on the roll 25 are alternately arranged with the multiple convex portions 24b of the roll 24, and are alternately arranged with the multiple convex portions of the roll 26.
  • the maximum diameter of the rolls 23, 24 is, for example, 100 mm or more and 200 mm or less.
  • the dimension of the convex portions 23b, 24b along the axial direction AD is, for example, 2 mm or more and 10 mm or less.
  • the gap between two adjacent convex portions 23b and the gap between two adjacent convex portions 24b are, for example, 5 mm or more and 20 mm or less. From the viewpoint of uniform pressure application to the laminate S, the dimension of the convex portions 23b, 24b along the axial direction AD and the above-mentioned gap may be approximately the same.
  • the protrusion amount of the convex portions 23b, 24b is, for example, 5 mm or more and 15 mm or less.
  • the smooth receiving rolls 30b-30e are provided below the rolls 23-26.
  • the smooth receiving rolls 30b-30e are receiving members corresponding to the rolls 23-26, respectively, and are spaced apart from the rolls 23-26.
  • the gap between the roll 23 and the smooth receiving roll 30b is approximately the same as the minimum gap between the crown roll 22 and the smooth receiving roll 30a.
  • each of the smooth receiving rolls 30b-30e is also provided within the conveying section 7.
  • the smooth roll 27 is a member that evenly pressurizes the laminate S to flatten the surface of the laminate S, and is located downstream of the rolls 23 to 26.
  • the smooth roll 27 is located at the most downstream position in the pressing section 8.
  • the dimension of the smooth roll 27 along the axial direction AD is approximately the same as that of the crown roll 22, for example.
  • the material of the smooth roll 27 is not particularly limited, and may be, for example, metal, alloy such as stainless steel, rubber, plastic, etc.
  • the outer diameter of the smooth roll 27 is not particularly limited, and may be, for example, 50% to 90% of the outer diameter OD1 of the crown roll 22.
  • a smooth support roll 30f is provided below the smooth roll 27.
  • the smooth support roll 30f is a support member corresponding to the smooth roll 27 and is spaced apart from the smooth roll 27.
  • the gap between the smooth roll 27 and the smooth support roll 30f is approximately the same as the minimum gap between the crown roll 22 and the smooth support roll 30a.
  • the smooth support roll 30f is also provided within the conveying section 7.
  • the winding roll 9 is a member that winds up the first carrier film F1 and the second carrier film F2 that sandwich the laminate S, and is located at the most downstream position.
  • the winding roll 9 winds up the laminate S that has passed through all the rolls included in the pressure section 8.
  • the winding roll 9 that has wound up the laminate S is transported to a thermostatic machine or the like as necessary. This can promote chemical reactions (e.g., B-stage formation) of the first curable composition 3a and the second curable composition 6a contained in the laminate S.
  • the first curable composition 3a is applied onto the first carrier film F1 during transportation (first step).
  • first step a thin film of the first curable composition 3a is formed on the first carrier film F1.
  • cut pieces CC of carbon fiber RF are supplied onto the first curable composition 3a (second step).
  • the cut pieces CC obtained by the cutting device 12 are scattered in the air.
  • the scattered cut pieces CC land irregularly on the first curable composition 3a.
  • the cut pieces CC are provided uniformly without orientation on the first curable composition 3a.
  • the second curable composition 6a is applied onto the second carrier film F2 during transport (third process).
  • a thin film of the second curable composition 6a is formed on the second carrier film F2.
  • the third process is carried out, for example, in synchronization with the first and second processes. Therefore, the third process does not have to be carried out after the first process, or after the second process.
  • the first carrier film F1 and the second carrier film F2 are brought close to each other to form a laminate S including the first curable composition 3a and the second curable composition 6a to which the cut pieces CC are supplied (fourth step).
  • the first carrier film F1 and the second carrier film F2 are transported to the receiving roll 21 to form the laminate S.
  • the laminate S is pressed by the pressure unit 8 (fifth step).
  • the laminate S is pressed by the receiving roll 21, the crown roll 22, the rolls 23 to 26, the smooth roll 27, and the smooth receiving rolls 30a to 30f. This allows the curable composition to be impregnated into the reinforcing fiber RF, and the laminate S to be flattened.
  • the laminate S sandwiched between the first carrier film F1 and the second carrier film F2 is wound up.
  • the above steps are performed by the manufacturing device 1.
  • the laminate S wound on the winding roll 9 may be heated (aged), for example, by a thermostatic oven. In this case, a sheet molding compound with even better film peelability, etc. is obtained.
  • FIG. 4 is a schematic diagram of a sheet molding compound pressing device, and is an example of a device that can be used when a crown roll is used in the sheet molding compound pressing process.
  • the pressing device 100 shown in FIG. 4 is another part of a sheet molding compound manufacturing device, and is a separate device from the manufacturing device 1 shown in FIG. 1.
  • the pressing device 100 includes a delivery roll 101, a pressing section 102, and a take-up roll 103. Although not shown, the pressing device 100 may further include a smooth roll located between the pressing section 102 and the take-up roll 103.
  • the delivery roll 101 corresponds to, for example, the take-up roll 9 shown in FIG. 1.
  • the pressure applying section 102 is located downstream of the delivery roll 101.
  • the pressure applying section 102 has a crown roll 110 and a smooth receiving roll 30g.
  • the crown roll 110 and the smooth receiving roll 30g are the same as the crown roll 22 and the smooth receiving roll 30a, respectively, in the above embodiment, but are not limited to this.
  • the winding roll 103 is a member that winds up the first carrier film F1 and the second carrier film F2 that sandwich the laminate S1, and is located at the most downstream side of the pressure device 100.
  • the laminate S1 that is wound by the winding roll 103 corresponds to a sheet molding compound.
  • the method for obtaining a molded product from the sheet molding compound of the present invention is not particularly limited, and it can be molded by the same method as that for a general sheet molding compound.
  • One example is hot compression molding, which can be produced by a method including some or all of the following steps: peeling the carrier film from a sheet molding compound having a carrier film on both sides, stacking one or more sheets of the sheet molding compound from which the carrier film has been peeled off, placing the sheet molding compound in a mold, and molding with a compression molding machine.
  • the sheet molding compound of the present invention has little stickiness and excellent film peelability, so that molded products can be obtained efficiently.
  • the temperature of the mold can be set freely, but it is preferably in the range of 110 to 180°C, and it is preferable to heat it to the same temperature in advance.
  • the molding pressure of the compression molding machine can be set freely, but it is preferably in the range of 0.1 to 30 MPa.
  • the molding time can be set freely, but it is preferable to clamp the mold to impart the shape and cure the curable composition over a period of several tens of seconds to several minutes.
  • Air content of the curable compositions produced below was calculated by the following method.
  • Air content (volume%) (1-A/B) x 100
  • Viscosity of Curable Composition The viscosity of the curable composition prepared below was measured at 25° C. using a digital viscometer ("VISCO" manufactured by Atago Co., Ltd. The viscosity measurement was performed within 10 minutes after the preparation of the curable composition.
  • curable compositions (1) and (2) The ingredients other than the polyisocyanate compound were mixed in the ratios shown in Table 1 below and charged into a "stainless open drum KD-200L” manufactured by JFE Container Corporation. Using a “multimixer ST24-GPR(S)-3.7 (HR700 impeller)” manufactured by Satake Multimix Corporation, the mixture was stirred at a liquid temperature of 23°C for 3 minutes, and the air content was measured every minute and adjusted to the desired air content to obtain a pre-composition. Furthermore, the air content of the polyisocyanate compound was measured, and the sum of the products of the air contents of the pre-composition and the polyisocyanate compound and the blending mass ratio was regarded as the air content of the curable composition.
  • Epoxy group-containing compound (1) bisphenol A type epoxy resin, "Epicron 840" manufactured by DIC Corporation, epoxy equivalent 180 g/equivalent, viscosity 10,000 mPa ⁇ s (25° C.)
  • Epoxy group-containing compound (2) 1,4-butanediol diglycidyl ether, "XY-622” manufactured by ANHUI XINYUAN Chemical Co., Ltd., epoxy equivalent 115 g/equivalent, viscosity 14.9 mPa ⁇ s (25° C.)
  • Urethane catalyst zinc amine catalyst, KING INDUSTRIES “K-KAT XK-614"
  • Water absorbent Molecular sieve, "Molecular sieve 4A powder” manufactured by Union Showa Co., Ltd.
  • the flask was heated to 90°C under a gas flow of a 1:1 mixture of nitrogen and air. 0.18 parts by mass of 2-methylimidazole was added, heated to 110°C, and reacted for 10 hours. The reaction was terminated after confirming that the acid value had reached 6 mgKOH/g or less. After cooling to about 60° C., the mixture was removed from the reaction vessel to obtain a vinyl ester resin (2) having a hydroxyl value of 209 mgKOH/g.
  • Comparative Curable Composition (1') Comparative curable composition (1') was obtained in the same manner as in the preparation of curable composition (3), except that after stirring for 3 minutes at a liquid temperature of 23°C, the air content was not adjusted by additional stirring.
  • Example 1 Sheet molding compounds and molded products were produced as follows, and various evaluation tests were carried out. The evaluation results are shown in Table 3.
  • Manufacturing apparatus for sheet molding compound A manufacturing apparatus 1 shown in FIG. 1 was prepared. In the pressurizing section through which the laminate was passed, one crown roll, four uneven rolls, and one smooth roll were installed in that order from before the process. All of the receiving rolls installed under the conveyor belt for each roll were smooth rolls. The four uneven rolls were arranged so that the convex portions of adjacent uneven rolls were alternately positioned with each other in the axial direction. Details of each roll are as follows. Crown roll: center outer diameter 136 mm, both end outer diameter 130 mm, axial length 1300 mm, made of silicone rubber. Uneven roll: maximum shaft diameter 160 mm, directional length 1300 mm, convex width 3 mm, spacing between convex portions 9 mm, convex height 10 mm, made of stainless steel. Smooth roll: diameter 100 mm, axial length 1300 mm, made of stainless steel. Receiving roll: diameter 80 mm, axial length 1300 mm, made of stainless steel.
  • a sheet molding compound was manufactured using the manufacturing apparatus 1.
  • a laminate film of a polyethylene film and a polypropylene film was used as the first carrier film F1 and the second carrier film F2 shown in FIG. 1.
  • the amount of the curable composition applied to the first carrier film F1 and the second carrier film F2 was 860 g/m 2.
  • Carbon fiber roving (“T700SC-12000-50C” manufactured by Toray Industries, Inc.) was used as the carbon fiber RF, and the carbon fiber RF was cut to 12.5 mm by the cutting device 12 to form a cut piece CC. Then, the cut piece CC was dropped from the air so that there was no fiber directionality and the obtained sheet molding compound had a uniform thickness.
  • the cut piece CC was dropped so that the carbon fiber content in the sheet molding compound was 45 mass%.
  • the first carrier film F1 and the second carrier film F2 were brought close to each other to form a laminate S including the first curable composition 3a on which the cut pieces CC of carbon fiber were arranged, and the second curable composition 6a.
  • the laminate S was transported by a transfer belt and passed through a pressure unit 8, and then wound up by a winding roll 9.
  • the wound laminate S was then left to stand for 4 hours in a thermostatic chamber set at 25°C to obtain a sheet molding compound having a thickness of 1.7 mm.
  • the basis weight of the sheet molding compound was 2 kg/ m2 .
  • the surface roughness (Sdr) of the sheet molding compound was measured in accordance with ISO 25178 using a "Digital Microscope VHX-5000" manufactured by Keyence Corporation. Measurement sample: A sample of 80 mm square was cut out from the sheet molding compound, and the central 60 mm square area was used as the measurement area. The surface roughness (Sdr) of 50 samples cut out from random locations of the sheet molding compound was measured, and the arithmetic average was used as the surface roughness (Sdr) of the sheet molding compound.
  • the carrier film was peeled off from the sheet molding compound obtained above, and two pieces were cut to a diameter of 150 mm ⁇ . These were then stacked and placed in a mold set to a thickness of 1.3 mm.
  • the mold was pressed under the conditions of a mold temperature of 150 (upper mold)/140°C (lower mold) and a mold clamping speed of 5.5 mm/sec to obtain molded product 1.
  • the area of the molded product 1 obtained above was measured, and the expansion ratio from the initial area of the sheet molding compound (75 ⁇ 75 ⁇ cm 2 ) was calculated and evaluated according to the following criteria: The higher the expansion ratio, the better the moldability.
  • B Enlargement ratio is 1.3 or more and less than 1.5.
  • C Enlargement ratio is less than 1.3.
  • Example 2 to 6 and Comparative Example 1 Sheet molding compounds and molded products were produced and various evaluation tests were carried out in the same manner as in Example 1, except that various settings were changed as shown in Tables 3 to 5. The evaluation results are shown in Tables 3 to 5.
  • Roll first uneven roll
  • 23 a...surface 23b...protruding portion (first protruding portion), 24...roll (second uneven roll), 24a...surface, 24b...protruding portion (second protruding portion), 27...smooth roll, 30a-30g...smooth receiving roll, 100...deaeration device, 101...delivery roll, 102...deaeration section, 103...winding roll, 110...crown roll, CC...cut piece, F1...first carrier film, F2...second carrier film, OD1...outer diameter (center diameter), OD2...outer diameter (end diameter), RF...reinforcing fiber, S, S1...laminate.

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017078142A1 (ja) * 2015-11-05 2017-05-11 三菱レイヨン株式会社 連続炭素繊維束、シートモールディングコンパウンドおよびそれを用いて成形する繊維強化複合材料
WO2019026724A1 (ja) * 2017-07-31 2019-02-07 東レ株式会社 シートモールディングコンパウンド、プリプレグおよび繊維強化複合材料
WO2019054074A1 (ja) * 2017-09-15 2019-03-21 ウシオ電機株式会社 炭素繊維強化プラスチック構造体および加工装置
JP2021513578A (ja) * 2018-01-31 2021-05-27 東レ株式会社 プリプレグシート、及び低ボイド含有量繊維強化複合材料の製造に有用であるプリプレグスタック
WO2022024773A1 (ja) * 2020-07-30 2022-02-03 Dic株式会社 シートモールディングコンパウンド及び成形品の製造方法
WO2022045329A1 (ja) * 2020-08-31 2022-03-03 東レ株式会社 成形材料および繊維強化複合材料

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017078142A1 (ja) * 2015-11-05 2017-05-11 三菱レイヨン株式会社 連続炭素繊維束、シートモールディングコンパウンドおよびそれを用いて成形する繊維強化複合材料
WO2019026724A1 (ja) * 2017-07-31 2019-02-07 東レ株式会社 シートモールディングコンパウンド、プリプレグおよび繊維強化複合材料
WO2019054074A1 (ja) * 2017-09-15 2019-03-21 ウシオ電機株式会社 炭素繊維強化プラスチック構造体および加工装置
JP2021513578A (ja) * 2018-01-31 2021-05-27 東レ株式会社 プリプレグシート、及び低ボイド含有量繊維強化複合材料の製造に有用であるプリプレグスタック
WO2022024773A1 (ja) * 2020-07-30 2022-02-03 Dic株式会社 シートモールディングコンパウンド及び成形品の製造方法
WO2022045329A1 (ja) * 2020-08-31 2022-03-03 東レ株式会社 成形材料および繊維強化複合材料

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