JP7534867B2 - Press molding materials, moldings and tanks - Google Patents

Description

The present invention relates to a press molding material, a molded product, and a tank, and more specifically to a press molding material, a molded product containing a cured product of the press molding material, and a tank containing the molded product.

Conventionally, molded products made from molding materials containing reinforcing fibers (especially SMC (sheet molding compound)) have been useful as structures such as tanks, due to their excellent appearance, mechanical properties, and water resistance.

As such a molding material, for example, a sheet molding material containing an unsaturated polyester resin composition and glass has been proposed (see, for example, Patent Document 1 below).

Japanese Patent Application Publication No. 10-265660

On the other hand, during natural disasters such as earthquakes, excessive forces may be applied to molded products, so molded products are required to have even higher pressure resistance.

The present invention provides a press molding material for obtaining molded products with excellent pressure resistance, a molded product containing a cured product of the press molding material, and a tank containing the molded product.

The present invention [1] is a press molding material that includes a resin composition containing a double bond-containing curable polymer and reinforcing fibers, the reinforcing fibers including first reinforcing fibers having a fiber length of 46 mm or more and 56 mm or less.

The present invention [2] further includes the press molding material described in [1] above, in which the reinforcing fibers include second reinforcing fibers having a fiber length of 20 mm or more and 30 mm or less, and the blending ratio of the first reinforcing fibers is 10 mass % or more and 70 mass % or less with respect to the total amount of the first reinforcing fibers and the second reinforcing fibers.

The present invention [3] includes a molded article that contains a cured product of the molding material described in [1] or [2] above.

The present invention [4] includes a tank containing the molded article described in [3] above.

The press molding material of the present invention contains reinforcing fibers including first reinforcing fibers having a fiber length of 46 mm or more and 56 mm or less. Therefore, molded products obtained using this press molding material have excellent pressure resistance.

The molded article of the present invention contains a cured product of the press molding material of the present invention. Therefore, this molded article has excellent pressure resistance.

The tank of the present invention contains the molded article of the present invention. Therefore, the tank has excellent pressure resistance.

The press molding material of the present invention contains a resin composition and reinforcing fibers.

The resin composition includes a resin component that includes a double bond-containing curable polymer and a polymerizable monomer.

Examples of double bond-containing curable polymers include unsaturated polyesters and vinyl esters, with unsaturated polyesters being preferred.

Unsaturated polyesters are the polymerization products of polybasic acids and polyhydric alcohols.

The polybasic acid includes a polybasic acid having an ethylenically unsaturated double bond as an essential component (hereinafter referred to as an ethylenically unsaturated bond-containing polybasic acid) and a polybasic acid not having an ethylenically unsaturated double bond as an optional component (hereinafter referred to as an ethylenically unsaturated bond-free polybasic acid).

Examples of ethylenically unsaturated bond-containing polybasic acids include ethylenically unsaturated aliphatic dibasic acids such as maleic acid, fumaric acid, itaconic acid, and dihydromuconic acid, as well as halides of these acids, such as alkyl esters of these acids.

The ethylenically unsaturated bond-containing polybasic acid also includes acid anhydrides derived from the above ethylenically unsaturated aliphatic dibasic acids, such as maleic anhydride.

Preferred examples of the ethylenically unsaturated bond-containing polybasic acid include maleic anhydride and fumaric acid.

Examples of polybasic acids not containing ethylenically unsaturated bonds include saturated aliphatic polybasic acids, saturated alicyclic polybasic acids, aromatic polybasic acids, halides of these acids, and alkyl esters of these acids.

Examples of saturated aliphatic polybasic acids include saturated aliphatic dibasic acids such as oxalic acid, malonic acid, succinic acid, methylsuccinic acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, hexylsuccinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, 2,2-dimethylglutaric acid, 3,3-dimethylsuccinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

Saturated aliphatic polybasic acids also include acid anhydrides derived from the above-mentioned saturated aliphatic dibasic acids, such as oxalic anhydride and succinic anhydride.

Examples of saturated alicyclic polybasic acids include saturated alicyclic dibasic acids such as HET acid, 1,2-hexahydrophthalic acid, 1,1-cyclobutanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid (cis- or trans-1,4-cyclohexanedicarboxylic acid or a mixture thereof), and dimer acid.

The saturated alicyclic polybasic acid includes anhydrides derived from the above-mentioned saturated alicyclic dibasic acids, such as HET anhydride.

Examples of aromatic polybasic acids include aromatic dibasic acids such as phthalic acid (orthophthalic acid, isophthalic acid, terephthalic acid), trimellitic acid, and pyromellitic acid.

Aromatic polybasic acids also include acid anhydrides derived from the above aromatic dibasic acids, such as phthalic anhydride.

The polybasic acid not containing an ethylenically unsaturated bond is preferably an aromatic polybasic acid, more preferably an aromatic dibasic acid, even more preferably phthalic acid, and particularly preferably isophthalic acid.

Polybasic acids can be used alone or in combination of two or more types.

When an ethylenically unsaturated bond-containing polybasic acid and an ethylenically unsaturated bond-free polybasic acid are used in combination, the blending ratio of the ethylenically unsaturated bond-containing polybasic acid to the polybasic acid is, for example, 50 mol % or more and, for example, 90 mol % or less.

Examples of polyhydric alcohols include alkane diols such as ethylene glycol, propylene glycol (1,2- or 1,3-propanediol or a mixture thereof), butylene glycol (1,2-, 1,3-, or 1,4-butylene glycol or a mixture thereof), 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,2-trimethylpentanediol, and 3,3-dimethylolheptane; aliphatic diols such as ether diols such as diethylene glycol, triethylene glycol, and dipropylene glycol; cyclohexanediol (1,2-, 1,3-, or 1,4-cyclohexanediol or a mixture thereof), cyclohexanedimethanol (1,2-, 1,3-, or 1,4-cyclohexanedimethanol or a mixture thereof); Examples of suitable alcohols include cyclohexanediethanol (1,2- or 1,3- or 1,4-cyclohexanediethanol or a mixture thereof), alicyclic diols such as hydrogenated bisphenol A, aromatic diols such as bisphenol A, ethylene oxide adducts of bisphenol A, and propylene oxide adducts of bisphenol A, trihydric alcohols such as glycerin, trimethylolpropane, and triisopropanolamine, tetrahydric alcohols such as tetramethylolmethane (pentaerythritol) and diglycerin, pentahydric alcohols such as xylitol, and hexahydric alcohols such as sorbitol, mannitol, allitol, iditol, dulcitol, altritol, inositol, and dipentaerythritol. Dihydric alcohols are preferred, aliphatic diols are more preferred, and alkanediols are even more preferred. Propylene glycol and neopentyl glycol are particularly preferred.

Polyhydric alcohols can be used alone or in combination of two or more types.

Unsaturated polyesters are obtained by polycondensation (condensation polymerization) of polybasic acids and polyhydric alcohols.

To polycondense (condensation polymerize) a polybasic acid and a polyhydric alcohol, they are mixed so that the equivalent ratio of the polyhydric alcohol to the polybasic acid (hydroxyl groups of the polyhydric alcohol/carboxyl groups of the polybasic acid) is, for example, 0.9 or more, preferably 0.95 or more, and, for example, 1.2 or less, preferably 1.1 or less, and stirred under normal pressure in a nitrogen atmosphere.

The reaction temperature is, for example, 150°C or higher, preferably 190°C or higher, and, for example, 250°C or lower, preferably 230°C or lower.

The reaction time is, for example, 8 hours or more and, for example, 30 hours or less.

In addition, in the above reaction, known solvents and known catalysts can be added as necessary.

This results in unsaturated polyester.

The acid value of the unsaturated polyester (measurement method: in accordance with JIS K6901 (2008)) is, for example, 20 mgKOH/g or more, preferably 25 mgKOH/g or more, and, for example, less than 40 mgKOH/g, preferably 30 mgKOH/g or less.

The double bond-containing curable polymers can be used alone or in combination of two or more types.

The blending ratio of the double bond-containing curable polymer is, for example, 25 parts by mass or more and, for example, 55 parts by mass or less per 100 parts by mass of the resin component.

The polymerizable monomer is a solvent for dissolving the double bond-containing curable polymer, and is 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 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, t-butyl (meth)acrylate, isobutyl (meth)acrylate; and 2-ethyl (meth)acrylate. (meth)acrylic acid alkyl esters such as (meth)acrylic acid allyl esters such as (meth)acrylic acid allyl esters such as (meth)acrylic acid allyl esters such as (meth)acrylic acid allyl esters such as (meth)acrylic acid allyl esters such as (meth)acrylic acid allyl esters such as (meth)acrylic acid cyclohexyl esters, (meth)acrylic acid benzyl esters, (meth)acrylic acid isobornyl esters, (meth)acrylic acid glycidyl esters, (meth)acrylic acid tetrahydrofurfuryl esters, (meth)acrylic acid dicyclopentenyl esters, (meth)acrylic acid dicyclopentanyl esters, (meth)acrylic acid dicyclopentenyl esters, (meth)acrylic acid dicyclopentenyloxyethyl esters such as (meth)acrylic acid ) (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl 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 such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate and chloride salts thereof; (meth)acrylic acid fluoroalkyl esters such as trifluoroethyl (meth)acrylate and heptadecafluorodecyl (meth)acrylate; Examples of suitable monomers include polyfunctional (meth)acrylic acid esters such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; and allyl monomers such as glycerin monoallyl ether, pentaerythritol diallyl ether, pentaerythritol monoallyl ether, and trimethylolpropane monoallyl ether. Preferred are styrene monomers, and more preferably styrene.

The polymerizable monomers can be used alone or in combination of two or more types.

The blending ratio of the polymerizable monomer is, for example, 20 parts by mass or more and, for example, 70 parts by mass or less, preferably 60 parts by mass or less, per 100 parts by mass of the resin component.

The resin component preferably also contains a shrinkage reducing agent.

When a molded article (described below) is obtained using this molding material, a low-shrinkage agent is added to suppress cure shrinkage and thermal shrinkage of the molded article (described below).

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

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.).

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.

The shrinkage reducing agent is preferably polystyrene.

Shrinkage reducing agents can be used alone or in combination of two or more types.

The proportion of the shrinkage reducing agent is, for example, 1 part by mass or more, preferably 3 parts by mass or more, and, for example, 30 parts by mass or less, preferably 20 parts by mass or less, per 100 parts by mass of the resin component.

The resin composition can be obtained by mixing the resin components, specifically the double bond-containing curable polymer, the polymerizable monomer, and the shrinkage reducing agent, which is added as needed, in the mixing ratios described above.

This results in a resin composition.

Additives such as polymerization inhibitors, curing agents, curing accelerators, wetting and dispersing agents, separation inhibitors, release agents, fillers, colorants, and thickeners can be added to the resin composition as needed. These additives can be used alone or in combination of two or more.

Examples of polymerization inhibitors 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-4-yl)succinic acid ester, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipate ester bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) n-butyl malonate, 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) Examples of N-oxyl compounds include 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)dodecylsuccinimide, 2,4,6-tris-[N-butyl-N-(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)]-s-triazine, and 1-oxyl-2,2,6,6-tetramethylpiperidin-4-one. Benzoquinone compounds are preferred, and p-benzoquinone is more preferred.

The mixing ratio of the polymerization inhibitor 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, per 100 parts by mass of the resin component.

Examples of curing agents include peroxides such as 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, t-hexylperoxybenzoate, and t-hexylperoxyacetate. Preferred are peroxyisopropyl monocarbonates such as t-butylperoxyisopropyl monocarbonate, t-amylperoxyisopropyl monocarbonate, t-hexylperoxyisopropyl monocarbonate, and t-butylperoxybenzoate. Preferred is t-butylperoxyisopropyl monocarbonate.

The mixing ratio of the hardener 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, per 100 parts by mass of the resin component.

Hardeners can be used alone or in combination of two or more types.

A curing accelerator can also be used in combination with the curing agent.

The curing accelerator is mixed with the above curing agent, and examples of such accelerators include organometallic compounds of cobalt, copper, and manganese, or their octoates, naphthenates, and acetylacetonates.

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

Cure accelerators can be used alone or in combination of two or more types.

Wetting and dispersing agents are added to improve the wettability of the resin components and reinforcing fibers, and examples of such agents include known wetting and dispersing agents such as polyester phosphate. Commercially available wetting and dispersing agents can also be used, such as BYK-W996 (manufactured by BYK-Chemie).

The mixing ratio of the wetting dispersant 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, per 100 parts by mass of the resin component.

Wetting and dispersing agents can be used alone or in combination of two or more types.

The separation prevention agent is added to prevent separation of the resin composition, and examples of such agents include block copolymers of styrene and vinyl acetate. Commercially available separation prevention agents can be used, such as BYK-W972 (manufactured by BYK-Chemie).

The mixing ratio of the separation prevention agent 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, per 100 parts by mass of the resin component.

Separation prevention agents can be used alone or in combination of two or more types.

Examples of release agents 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 alkyl ammonium salts, with fatty acid metal salts being preferred, and zinc stearate being more preferred.

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

Release agents can be used alone or in combination of two or more types.

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 fibers, conductive particles, and conductive fillers such as carbon nanotubes, and preferably carbonates, more preferably calcium carbonate.

The mixing ratio of the filler is, for example, 1 part by mass or more, preferably 10 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 80 parts by mass or more, and is, for example, 300 parts by mass or less, preferably 200 parts by mass or less, per 100 parts by mass of the resin component.

Fillers can be used alone or in combination of two or more types.

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

The blending ratio of the colorant is not particularly limited and is appropriately set depending on the application of the molded product. For example, it is 20 parts by mass or less, preferably 10 parts by mass or less, per 100 parts by mass of the resin component. In addition, in applications where design is required, it is preferable to contain a colorant.
For 100 parts by mass of the resin component, the amount is, for example, 1 part by mass or more, preferably 3 parts by mass or more, and for example, 20 parts by mass or less, preferably 10 parts by mass or less.

Colorants can be used alone or in combination of two or more types.

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 the reinforcing fibers (described below). 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), and preferably alkaline earth metal oxides, and more preferably magnesium oxide.

The mixing ratio of the thickener 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, per 100 parts by mass of the resin component.

Thickeners can be used alone or in combination of two or more types.

Additives such as pattern materials, flame retardants, antibacterial agents, hydrophilic agents, photocatalysts, UV absorbers, UV stabilizers, silane coupling agents, antistatic agents, thixotropic agents, thixotropic stabilizers, and polymerization accelerators can be blended into the resin composition as needed, provided that the effects of the present invention are not impaired. These additives can be used alone or in combination of two or more.

In the above explanation, the double bond-containing curable polymer, the polymerizable monomer, the low shrinkage agent that is added as needed, and the additives that are added as needed are mixed to obtain a resin composition. However, it is also possible to first prepare a double bond-containing curable resin by dissolving the double bond-containing curable polymer in the polymerizable monomer, and then mix the obtained double bond-containing curable resin with the polymerizable monomer, the low shrinkage agent that is added as needed, and the additives that are added as needed.

In preparing the double bond-containing curable polymer, the double bond-containing curable polymer and the polymerizable monomer are mixed, and the above-mentioned additives can also be mixed as necessary.

Examples of reinforcing fibers include inorganic fibers such as glass fibers, carbon fibers, metal fibers, and ceramic fibers; organic fibers such as polyvinyl alcohol fibers, polyester fibers, polyamide fibers, fluororesin fibers, and phenolic fibers; and natural fibers such as hemp and kenaf. Inorganic fibers are preferred, and from the viewpoint of flexural modulus, carbon fibers are more preferred, and from the viewpoint of pressure resistance, glass fibers are preferred.

These reinforcing fibers may have the following shapes: cloth-like fibers such as roving cloth; mat-like fibers such as chopped strand mat, preformable mat, continuous strand mat, and surfacing mat; strand-like fibers such as chopped strand; roving-like fibers; nonwoven fabric-like fibers; and paper-like fibers, preferably roving-like fibers.

And the reinforcing fibers have a predetermined fiber length.

The fiber length can be determined in accordance with the test item "chopped strand length" in the general test method for glass fibers (JIS R3420 (2013)).

Specifically, the reinforcing fibers include first reinforcing fibers having a fiber length of 46 mm or more, preferably 48 mm or more, and 56 mm or less, preferably 54 mm or less.

If the reinforcing fibers include the first reinforcing fibers, the molded product (described below) obtained using this press molding material has excellent pressure resistance.

On the other hand, if the reinforcing fibers do not contain the first reinforcing fibers, the pressure resistance of the molded product (described below) obtained using this press molding material will decrease.

In addition, the reinforcing fibers preferably include, together with the first reinforcing fibers, second reinforcing fibers having a fiber length of 20 mm or more, preferably 22 mm or more, and 30 mm or less, preferably 28 mm or less.

If the reinforcing fibers include a second reinforcing fiber, the molded product (described below) obtained using this press molding material will have even greater pressure resistance.

When the reinforcing fibers include a second reinforcing fiber (i.e., when the reinforcing fibers include a first reinforcing fiber and a second reinforcing fiber), the mixing ratio of the first reinforcing fiber is, for example, 5% by mass or more, preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 30% by mass or more, particularly preferably 40% by mass or more, and, for example, 90% by mass or less, preferably 70% by mass or less, more preferably 60% by mass or less, based on the total amount of the first reinforcing fiber and the second reinforcing fiber.

If the blending ratio of the first reinforcing fiber is equal to or greater than the lower limit, the molded product (described below) obtained using this press molding material will have even better pressure resistance.

In addition, if the blending ratio of the first reinforcing fiber is equal to or less than the above upper limit, the molded product (described below) obtained using this press molding material will have even better pressure resistance.

The reinforcing fibers preferably consist only of the first reinforcing fibers and the second reinforcing fibers.

The press molding material is obtained by blending reinforcing fibers into the resin composition.

Specifically, the press molding material is obtained, for example, in the form of a sheet, by impregnating reinforcing fibers with a resin composition.

Methods for preparing press molding materials include known methods, such as SMC (sheet molding compound), TMC (thick molding compound), and BMC (bulk molding compound), with SMC being preferred.

The content of reinforcing fibers in the press molding material is, for example, 20% by mass or more, preferably 30% by mass or more, and, for example, 50% by mass or less.

This results in a press molding material containing the resin composition and reinforcing fibers.

Then, in order to thicken such press molding material so that it can be subjected to hot compression molding (described later), it is preferably aged, for example, at a temperature of 20°C or higher and 50°C or lower, for 8 hours or longer and 120 hours or shorter.

This allows the press molding material to be held in a shape, for example, a sheet. In other words, the press molding material has a sheet shape.

Such press molding materials are then molded using a press molding method.

The press molding method is a heat compression molding method in which the press molding material is heated and pressurized in a mold equipped with a hydraulic press to form the material.

The conditions for the press molding method 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 3 MPa or higher, and for example, 20 MPa or lower, preferably 15 MPa or lower.

This causes the press molding material to harden and form.

This results in a molded product containing the hardened press molding material.

This molded product has excellent pressure resistance because it contains the hardened press molding material.

Specifically, the pressure resistance of the molded product is, for example, 0.7 kgf/ ^cm2 or more, preferably 0.76 kgf/ ^cm2 or more, more preferably 0.79 kgf/ ^cm2 or more, even more preferably 0.85 kgf/ ^cm2 or more, particularly preferably 0.89 kgf/ ^cm2 or more, and most preferably 0.91 kgf/ ^cm2 or more, and is, for example, 1.2 kgf/ ^cm2 or less.

The method for measuring the pressure resistance will be described in detail in the examples below.

The flexural strength of the molded product (based on JIS K7074 (1988)) is, for example, 200 MPa or more, preferably 230 MPa or more, more preferably 245 MPa or more, even more preferably 250 MPa or more, particularly preferably 255 MPa or more, and most preferably 260 MPa or more, and is, for example, 400 MPa or less.

The flexural modulus of the molded product (based on JIS K7074 (1988)) is, for example, 10 GPa or more, preferably 13 GPa or more, more preferably 14 GPa or more, and is, for example, 30 GPa or less.

The Izod impact value (based on JIS K7062 (1992)) of the molded article is, for example, 30 kJ/ ^m2 or more, preferably 50 kJ/ ^m2 or more, more preferably 65 kJ/ ^m2 or more, and even more preferably 70 kJ/ ^m2 or more, and is, for example, 100 kJ/m2 or ^less .

The thickness of the molded product is, for example, 3 mm or more, preferably 5 mm or more, and, for example, 30 mm or less, preferably 15 mm or less.

These molded products can be used for a wide range of applications, including building materials, housings, casting materials, machine parts, electronic and electrical parts, vehicles, ships, aircraft, tanks, and more.

In particular, such molded products have excellent pressure resistance and are therefore suitable for use in tanks.

Since such tanks contain the above-mentioned molded products, they have excellent pressure resistance.

Specific numerical values of the blending ratio (content ratio), physical property values, parameters, etc. used in the following description can be replaced with the upper limit values (numerical values defined as "not more than" or "less than") or lower limit values (numerical values defined as "not less than" or "exceeding") of the corresponding blending ratio (content ratio), physical property values, parameters, etc. described in the above "Description of the Invention." In addition, unless otherwise specified in the following description, "parts" and "%" are based on mass.
1. Preparation of Unsaturated Polyester Resin Synthesis Example 1
A flask equipped with a thermometer, a nitrogen gas inlet tube, a reflux condenser, and a stirrer was used as a reactor. 2.0 mol of isophthalic acid, 5.5 mol of propylene glycol, and 5.0 mol of neopentyl glycol were charged into this reactor, and polycondensation reaction was carried out at a temperature of 200 to 210°C while stirring under a nitrogen gas atmosphere. When the acid value reached 10 mgKOH/g, the mixture was cooled to 150°C, 8.0 mol of maleic anhydride was charged, and the reaction was carried out again at 210 to 220°C to obtain an unsaturated polyester with an acid value of 27.0 mgKOH/g.

Next, 43 parts by mass of the obtained unsaturated polyester was mixed with 47 parts by mass of styrene to obtain an unsaturated polyester resin.
2. Preparation of press molding material
Comparative Example 6
A resin composition was obtained by mixing 90 parts by mass of the unsaturated polyester resin of Synthesis Example 1 (i.e., 43 parts by mass of unsaturated polyester, 47 parts by mass of styrene), 10 parts by mass of polystyrene powder, 0.05 parts of p-benzoquinone as a polymerization inhibitor, 1.0 part of t-butylperoxyisopropyl monocarbonate as a curing agent, 5 parts of zinc stearate as a release agent, 5 parts of polyester toner (a pigment containing titanium oxide dispersed in an unsaturated polyester resin, ivory color) as a colorant, and 110 parts of calcium carbonate as a filler.

Next, 1.0 part of magnesium oxide was added to the resin composition as a thickener, and then the reinforcing fiber roving was added in such a ratio that the reinforcing fiber content when cut continuously to 25 mm was 3 mass % and the reinforcing fiber content when cut to 51 mm was 35 mass %. A press molding material (SMC) with a thickness of 2 mm was prepared using a known SMC impregnation machine.

Examples 2 to 7 and Comparative Examples 1 to 7
Except for changing the compounding formulation according to the description in Table 1, the same treatment as in Comparative Example 6 was carried out to obtain a press molding material.
3. Evaluation <Evaluation>
(Moldability (mini-tank type filling ability))
Each press molding material (SMC sheet) of each Example and Comparative Example was cut to a size of 300 mm x 450 mm, and 14 sheets were stacked and put into a mini-tank mold, and a mini-tank molded product with a length of 350 mm, a width of 600 mm, and a height of 300 mm was obtained under the conditions of molding temperature upper mold/lower mold = 145 ° C./140 ° C., keeping time of 360 seconds, and molding pressure of 4 MPa. The appearance of the mini-tank molded product was then confirmed, and moldability was evaluated according to the following criteria. The results are shown in Table 1.
○: No filling defects were observed.
×: Not completely filled.

(Flexural strength, flexural modulus)
From each press molding material of each Example and Comparative Example, a flat mold (300mm x 300mm) was used to obtain a flat molded product (300mm x 300mm) under the conditions of molding temperature upper mold / lower mold = 145 ° C / 130 ° C, keep time 360 seconds, molding pressure surface pressure 10 MPa. Then, a test piece (length 80mm, width 10mm) was cut out from the flat molded product, and the bending strength and bending modulus were measured in accordance with JIS K6911 (1995). The results are shown in Table 1.

(Izod impact test)
In the same manner as in the bending strength and bending modulus measurements, flat plate molded products (300 mm x 300 mm) were obtained from the press molding materials of each Example and Comparative Example. Then, test pieces (length 65 mm, width 10 mm) were cut out from the flat plate molded products, and Izod impact tests were carried out in accordance with JIS K7062 (1992). The tests were carried out under the conditions of flatwise and without notches. The results are shown in Table 1.

(Compression resistance)
Three sheets of the press molding material (SMC sheet) of each Example and Comparative Example cut to a size of 280 mm x 280 mm and one sheet of continuous strand mat (weight per unit area 300 g/m ² ) cut to a size of 300 mm x 300 mm were stacked and put into a flat plate mold (300 mm x 300 mm), and a flat plate molded product (300 mm x 300 mm) was obtained under the conditions of molding temperature upper mold/lower mold = 145 ° C / 140 ° C, keep time 360 seconds, and molding pressure surface pressure 4 MPa. Meanwhile, an iron container was prepared with dimensions of 300 mm x 300 mm (opening 270 mm) and 100 mm deep, only the top surface was open, water could be introduced from the bottom, and a water pressure gauge was attached at a depth of 50 mm. The flat plate molded product (300 mm x 300 mm) was fixed to the outer periphery of the top surface of the container via a rubber packing, and the inner surface of the container was completely sealed. Then, water was poured into the container until it was full, and when it was full, it was left for 5 minutes. After that, water was poured in so that the water pressure increased at a rate of 0.05 kgf/ ^cm2 min, and the water pressure at which the molded product broke was measured. This breaking water pressure was taken as the pressure resistance strength.

Claims (4)

A press molding material comprising a resin composition containing a double bond-containing curable polymer and reinforcing fibers,
the double bond-containing curable polymer is an unsaturated polyester and/or a vinyl ester;
The reinforcing fibers include first reinforcing fibers having a fiber length of 46 mm or more and 56 mm or less, and second reinforcing fibers having a fiber length of 20 mm or more and 30 mm or less,
The blending ratio of the reinforcing fibers is 30% by mass or more and 50% by mass or less with respect to the press molding material,
A press molding material, characterized in that the blending ratio of the first reinforcing fibers is 10% by mass or more and 72% by mass or less with respect to the total amount of the first reinforcing fibers and the second reinforcing fibers . The press molding material according to claim 1, characterized in that the blending ratio of the first reinforcing fiber is 10% by mass or more and 70% by mass or less with respect to the total amount of the first reinforcing fiber and the second reinforcing fiber. A molded article comprising a cured product of the molding material according to claim 1 or 2. A tank comprising the molded article according to claim 3.