Curable resin composition, fiber-reinforced molding material, molded article, polyol, and method for producing the same

Abstract

To provide a curable resin composition, a fiber-reinforced molding material, and a molded article, each employing an amino acid as at least one raw material, and further to provide a polyol compound employing an amino acid as at least one raw material, and a method for producing the same.SOLUTION: A curable resin composition of the present invention comprises a urethane (meth)acrylate resin (A), a (meth)acrylate monomer (B), and a polymerization initiator (C). The urethane (meth)acrylate (A) is a reaction product of a polyisocyanate (a1), a polyol (a2) having an amino acid skeleton, and a hydroxyalkyl (meth)acrylate (a3). The polyol (a2) having an amino acid skeleton is a reaction product of an amino acid and a cyclic carbonate compound.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a curable resin composition, a fiber-reinforced molding material, a molded article, a polyol, and a method for producing the same.

Background Art

[0002] Conventionally, a fiber-reinforced molding material containing a curable resin composition containing a urethane (meth) acrylate resin or the like and reinforcing fibers such as glass fibers and carbon fibers has been known (see, for example, Patent Document 1). Such fiber-reinforced molding materials are attracting attention for their characteristics of being lightweight while having excellent heat resistance, mechanical strength, and durability, and their use in various applications such as structural members for automotive members, housing equipment members, etc., sports members, and housings for OA equipment is expanding.

[0003] In recent years, from the perspective of building a sustainable society, reduction in the use amount of petroleum-derived raw materials, conversion to chemical raw materials via non-petroleum processes, etc. have been demanded. Therefore, it is desired to use an amino acid for which fermentation production technology has been established and which has excellent supply capacity as one raw material of the curable resin composition.

[0004] For example, Non-Patent Document 1 discloses a technique for obtaining an ω-hydroxycarboxylic acid derived from L-phenylalanine and ethylene carbonate. However, in order to use the ω-hydroxycarboxylic acid as one raw material of a curable resin composition containing the above-mentioned urethane (meth) acrylate resin or the like, there is a disadvantage that a step of modifying the carboxyl group of the ω-hydroxycarboxylic acid is further required. In addition, the method disclosed in Non-Patent Document 1 has disadvantages such as the use of a large amount of reagents, a low yield of 17%, and the generation of a large amount of waste, and is not suitable for industrialization.

Prior Art Documents

Patent Documents

[0005] International Publication No. 2021 / 131564

Non-Patent Documents

[0006] [Non-Patent Document 1] Nobuhiro Kihara et al., "Polycondensation of ω-Hydroxy Carboxylic Acid Derived from L-Phenylalanine and Ethylene Carbonate", Journal of Polymer Science Part A: Polymer Chemistry, Volume 34, Issue 9 p. 1819-1822 (1996) [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] The problems to be solved by the present invention are to provide a curable resin composition, a fiber-reinforced molding material, and a molded article using at least one amino acid as a raw material. Further, it is to provide a polyol compound using at least one amino acid as a raw material and a method for producing the same. [Means for Solving the Problems]

[0008] The curable resin composition according to the present invention is a curable resin composition containing a urethane (meth) acrylate resin (A), a (meth) acrylate monomer (B), and a polymerization initiator (C), wherein the urethane (meth) acrylate (A) is a reaction product of a polyisocyanate (a1), a polyol (a2) having an amino acid skeleton, and a hydroxyalkyl (meth) acrylate (a3), and the polyol (a2) having an amino acid skeleton is a reaction product of an amino acid and a cyclic carbonate compound.

[0009] The fiber-reinforced molding material according to the present invention is characterized by containing the above-described curable resin composition and reinforcing fibers.

[0010] The molded article according to the present invention is characterized by using the above-described fiber-reinforced molding material.

[0011] The polyol according to the present invention has an amino acid skeleton and is a reaction product of an amino acid and a cyclic carbonate compound.

[0012] The method for producing a polyol according to the present invention is characterized in that an amino acid and a cyclic carbonate compound are mixed and heated at a temperature of 100 to 150 ° C. without a solvent until the acid value becomes 1 mg KOH / g or less to obtain a polyol having an amino acid skeleton.

Effects of the Invention

[0013] According to the present invention, it is possible to provide a curable resin composition, a fiber-reinforced molding material, and a molded article using at least one amino acid as a raw material. Further, according to the present invention, it is possible to provide a polyol using at least one amino acid as a raw material and a method for producing the same.

Modes for Carrying Out the Invention

[0014] The curable resin composition according to an embodiment of the present invention is a curable resin composition containing a urethane (meth) acrylate resin (A), a (meth) acrylate monomer (B), and a polymerization initiator (C), wherein the urethane (meth) acrylate (A) is a reaction product of a polyisocyanate (a1), a polyol (a2) having an amino acid skeleton, and a hydroxyalkyl (meth) acrylate (a3), and the polyol (a2) having an amino acid skeleton is a reaction product of an amino acid and a cyclic carbonate compound. The curable resin composition may be a thermosetting resin composition or a photocurable resin composition, but is preferably a thermosetting resin composition because a molded article having a freely controllable thickness can be obtained, a molded article having a higher degree of curing can be obtained, and the like.

[0015] The urethane (meth) acrylate resin (A) is a reaction product of a polyisocyanate (a1), the polyol (a2) having an amino acid skeleton, and a hydroxyalkyl (meth) acrylate (a3).

[0016] Since the heat resistance of the molded article is further improved, the polyisocyanate (a1) preferably contains a polyisocyanate having a cyclic skeleton. These polyisocyanates (a1) can be used alone or in combination of two or more.

[0017] Examples of the polyisocyanate (a1) include 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, carbodiimide-modified product of 4,4'-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, nurate-modified product of diphenylmethane diisocyanate, burette-modified product, urethane imine-modified product, polyol-modified product modified with a polyol having a number average molecular weight of 1,000 or less such as diethylene glycol or dipropylene glycol, tolylene diisocyanate (TDI), tolidine diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, tetramethylxylylene diisocyanate and other aromatic polyisocyanates; alicyclic polyisocyanates such as isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, norbornene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, nurate-modified product of hexamethylene diisocyanate, burette-modified product, adduct product, dimer acid diisocyanate and the like. Among these, since the heat resistance of the molded article is further improved, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, carbodiimide-modified product of 4,4'-diphenylmethane diisocyanate, and polymethylene polyphenyl polyisocyanate, norbornene diisocyanate, xylylene diisocyanate, isophorone diisocyanate (IPDI) are preferable. In addition, these polyisocyanates (a1) can be used alone or in combination of two or more.

[0018] The polyol (a2) having an amino acid skeleton is a reaction product of an amino acid and a cyclic carbonate compound.

[0019] An amino acid is an organic compound that has both a carboxyl group and an amino group and further has a side chain. Various amino acids can be mentioned, such as amino acids having a carboxyl group, an amino group, an alkyl group, a hydroxy group, an amide group, an imino group, an aromatic skeleton, etc. in the side chain. The amino acid may be any of α - amino acid, β - amino acid, γ - amino acid, δ - amino acid, and the α - amino acid may be either the L - form or the D - form. The amino acid is not limited to natural amino acids and may be an amino acid derivative in which various groups are introduced into the side chain of natural amino acids.

[0020] The amino acid is preferably at least one amino acid selected from the group consisting of an amino acid having a hydrophobic side chain, an amino acid having a carboxyl group in the side chain and having a protecting group on the carboxyl group of the side chain, an amino acid having an amino group in the side chain and having a protecting group on the amino group of the side chain, an amino acid having an alcoholic hydroxy group in the side chain and having a protecting group on the hydroxy group of the alcoholic hydroxy group, and an amino acid having a phenolic hydroxy group in the side chain and having a protecting group on the hydroxy group of the phenolic hydroxy group. The curable resin composition using these amino acids as raw materials can obtain a molded article having more excellent strength as compared with the curable resin composition using other amino acids as one of the raw materials.

[0021] Among the amino acids having a hydrophobic side chain, examples of α - amino acids include glycine, alanine, valine, norvaline, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan, etc. Examples of β - amino acids include β - alanine, etc. Examples of γ - amino acids include γ - aminobutyric acid (4 - aminobutanoic acid), etc.

[0022] Examples of the amino acid having a carboxyl group in the side chain and a protecting group in the carboxyl group of the side chain include those having a protecting group in the carboxyl group of the side chain of aspartic acid or glutamic acid. The protecting group is not particularly limited, and examples thereof include an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, and an aralkyl group having 7 to 11 carbon atoms. Specifically, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a phenyl group, a benzyl group, a phenacyl group, a cyclohexyl group, etc. can be mentioned. Among them, as the protecting group, an alkyl group having 1 to 4 carbon atoms is more preferable. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group. Further, aspartic acid having the protecting group in the α-carboxyl group may be used as a β-amino acid, and glutamic acid having a similar protecting group may be used as a γ-amino acid.

[0023] Examples of the amino acid having an amino group in the side chain and a protecting group in the amino group of the side chain include those having a protecting group in the amino group of the side chain of lysine or ornithine. The protecting group is not particularly limited, and examples thereof include an acyl group and a urethane-type protecting group. Examples of the acyl group include an acetyl group, a propionyl group, and a butanoyl group. Examples of the urethane-type protecting group include a 9-fluorenylmethyloxycarbonyl group, a benzyloxycarbonyl group, and a t-butoxycarbonyl group. Among them, as the protecting group, an acyl group such as an acetyl group, a propionyl group, or a butanoyl group is more preferable.

[0024] Examples of the amino acid having an alcoholic hydroxy group in the side chain and having a protecting group on the alcoholic hydroxy group include those having a protecting group on the hydroxy group of the alcoholic hydroxy group of serine, threonine, or hydroxyproline. The protecting group is not particularly limited, and examples thereof include an acyl group, an alkoxycarbonyl group, an alkyl group, and an aralkyl group. Examples of the acyl group include acyl groups having 1 to 8 carbon atoms such as an acetyl group, an isobutyroyl group, a pivaloyl group, a benzoyl group, and a 4-toluoyl group. Examples of the alkoxycarbonyl group include a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, a butoxycarbonyl group, and a sec-butoxycarbonyl group. Examples of the alkyl group include alkyl groups having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a t-butyl group. Examples of the aralkyl group include aralkyl groups having 7 to 21 carbon atoms such as a benzyl group and a 4-monomethoxybenzyl group. Other protecting groups include a methoxymethyl group, a methylthiomethyl group, a benzyloxymethyl group, a methoxyethoxymethyl group, and a tetrahydropyranyl group.

[0025] Examples of the amino acid having a phenolic hydroxy group in the side chain and having a protecting group on the phenolic hydroxy group include those having a protecting group on the hydroxy group of the phenolic hydroxy group of tyrosine or dopa. The protecting group is not particularly limited, and examples thereof include an alkyl group and an aralkyl group. For example, alkyl groups having 1 to 4 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a t-butyl group can be mentioned. Examples of the aralkyl group include aralkyl groups having 7 to 21 carbon atoms such as a benzyl group and a 4-monomethoxybenzyl group.

[0026] Among the above-mentioned amino acids, in particular, the amino acids having the hydrophobic side chains are more preferable. As the α-amino acids having the hydrophobic side chains, alanine, valine, norvaline, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan and the like are preferable. β-alanine which is a β-amino acid having the hydrophobic side chain and γ-aminobutyric acid which is a γ-amino acid having the hydrophobic side chain are preferable. When high strength is required for the molded article, it is particularly preferable that the hydrophobic side chain is a short chain, and examples thereof include alanine, valine, norvaline, leucine, isoleucine, phenylalanine, β-alanine, and γ-aminobutyric acid. α-Amino acids having an alkyl group or an aromatic skeleton in the side chain are more preferable, and examples thereof include alanine, valine, norvaline, leucine, isoleucine, and phenylalanine.

[0027] As the cyclic carbonate compound, those having only one cyclic carbonate group in the molecule are preferable, and it is preferable that they are one or more carbonates selected from the group consisting of ethylene carbonate, propylene carbonate, and glycerin carbonate. The curable resin composition containing the polyol compound (a2) obtained by reacting such a cyclic carbonate compound with an amino acid can contain more amino acid skeletons than the case where it contains a polyol (a2) obtained using other cyclic carbonate compounds, and thus a molded article having more excellent strength can be obtained.

[0028] The polyol (a2) having the amino acid skeleton is a reaction product of an amino acid and a cyclic carbonate compound, and can be obtained, for example, by heating and mixing. When performing the heating and mixing, an organic solvent may be used, but since a solvent removal step is required after the heating and mixing, it is preferably performed without a solvent.

[0029] Specifically, an amino acid and a cyclic carbonate compound are placed in a reaction vessel at room temperature. At this time, a catalyst may be added as necessary. Heat gradually and raise the temperature to 100-150 °C. At this time, since carbon dioxide gas is generated with heating, for example, after once holding the temperature at 120 °C and then the generation of gas decreases, the temperature may be raised to a predetermined reaction temperature. Keep heating until the content becomes transparent, and measure the acid value of the content after the content becomes transparent. When the acid value becomes 1 KOHmg / g or less, stop heating, cool to 60 °C, and take out the content.

[0030] By heating the amino acid and the cyclic carbonate compound, a reaction occurs to form a polyol (2) having an amino acid skeleton. Although the reaction mechanism is not clear, the following reactions are considered to occur.

[0031] For example, the case of heating L-valine and ethylene carbonate will be described. (1) By adding ethylene carbonate to the α-amino group of L-valine, N-(2-hydroxyethoxy)carbonyl-L-valine is produced. (2) While the product dissolves in the system, the α-carboxyl group of the remaining L-valine reacts with ethylene carbonate, and an esterification reaction occurs while generating carbon dioxide. As a result, N-(2-hydroxyethoxy)carbonyl-L-valine (2-hydroxyethyl ester), that is, a polyol (2) having an amino acid skeleton is produced.

[0032]

Chemical formula

[0033] The mixing ratio (molar ratio) of the cyclic carbonate compound to the amino acid is preferably 1.9 to 2.4, more preferably 2.0 to 2.3. When the molar ratio is less than 1.9, it takes a long time for the acid value to reach 1 KOH mg / g or less. On the other hand, when the molar ratio exceeds 2.3, unreacted cyclic carbonate compounds may remain, and the strength properties of the molded product may deteriorate. In order to prevent unreacted cyclic carbonate compounds from remaining in the extracted content, after confirming the acid value, the unreacted cyclic carbonate compounds may be removed by decompression treatment.

[0034] As the catalyst, a catalyst for epoxy resin or the like can be used. Specifically, phosphines such as triphenylphosphine, quaternary phosphonium salts such as tetrabutylphosphonium bromide, quaternary ammonium salts such as tetrabutylammonium bromide, carbonates such as potassium carbonate, tertiary amines such as triethylamine and diazabicycloundecene, tin compounds such as dibutyltin oxide and dibutyltin diacetate, zinc compounds such as zinc octylate, titanium compounds such as tetrabutyl titanate, and germanium compounds such as germanium oxide. Among them, quaternary phosphonium which can promote the reaction in a small amount is preferable.

[0035] During the heating, in order to prevent the content from coloring, it is preferable to flow an inert gas such as nitrogen gas, argon gas, or xenon gas into the reaction vessel.

[0036] Examples of the hydroxyalkyl (meth)acrylate (a3) include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxy-n-butyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-n-butyl (meth)acrylate, 3-hydroxy-n-butyl (meth)acrylate, and the like. Among these, 2-hydroxyethyl (meth)acrylate is preferable from the balance of strength properties. These hydroxyalkyl (meth)acrylates (a4) can be used alone or in combination of two or more.

[0037] Further, if necessary, as a raw material of the urethane (meth) acrylate (A), other polyols other than the polyol (a2) having the amino acid skeleton can be used in combination. As the other polyol, polyester polyol, acrylic polyol, polyether polyol, polycarbonate polyol, polyalkylene polyol, etc. can be used.

[0038] The molar ratio (NCO / OH) of the isocyanate group (NCO) of the isocyanate compound, which is a raw material of the urethane (meth) acrylate (A), to the hydroxy group (OH) of the polyol (a2) having an amino acid skeleton and the hydroxyalkyl (meth) acrylate (a3) is preferably 0.7 to 1.3, more preferably 0.8 to 1.1, and even more preferably 0.8 to 1.0, from the balance of heat resistance and strength physical properties.

[0039] As the (meth)acrylate monomer (B), it is desirable to use a compound derived from biomass, but since the types are limited, it is not particularly limited. It is appropriately selected according to the application physical properties. For example, monofunctional (meth)acrylate compounds such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, furfuryl (meth)acrylate, benzyl (meth)acrylate, methylbenzyl (meth)acrylate, phenoxyethyl (meth)acrylate, methylphenoxyethyl (meth)acrylate, etc.; di(meth)acrylate compounds such as ethylene glycol di(meth)acrylate, 1,3-propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, di(meth)acrylate of an ethylene oxide adduct of isosorbide, furan dimethanol di(meth)acrylate, etc.; and glycerin (meth)acrylate compounds such as glycerin (meth)acrylate, glycerin di(meth)acrylate, glycerin tri(meth)acrylate, diglycerin tri(meth)acrylate, diglycerin tetra(meth)acrylate, ethylene oxide-modified products and propylene oxide-modified products thereof, etc. These can be used alone or in combination of two or more.

[0040] Among these, in view of the volatility during use and the handling of dangerous substances, as well as the mechanical strength and heat resistance of the molded body, (meth)acrylates having a molecular weight of 150 to 400 are preferred, and isobornyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, furfuryl (meth)acrylate, phenoxyethyl (meth)acrylate, methylphenoxyethyl (meth)acrylate, benzyl (meth)acrylate, methylbenzyl (meth)acrylate, 1,6 - hexanediol di(meth)acrylate, 1,10 - decanediol di(meth)acrylate, 1,12 - dodecanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, and franj methanol di(meth)acrylate are more preferred.

[0041] In addition, since the balance among the handleability of the (deleted prepreg) resin composition and the molding material, the quality of the molded product, and productivity is further improved, the content of the (meth)acrylate monomer (B) in the total of the urethane (meth)acrylate resin (A) and the (meth)acrylate monomer (B) (hereinafter abbreviated as "content (B)") is preferably 5 to 50% by mass, and more preferably 10 to 40% by mass.

[0042] The polymerization initiator (C) is not particularly limited, but organic peroxides are preferred. Examples include diacyl peroxide compounds, peroxyester compounds, hydroperoxide compounds, ketone peroxide compounds, alkyl perester compounds, percarbonate compounds, peroxyketals, etc., and they can be appropriately selected according to the molding conditions. These polymerization initiators (C) can be used alone or in combination of two or more.

[0043] Among these, for the purpose of shortening the molding time, it is preferable to use a polymerization initiator having a 10-hour half-life at a temperature of 60°C or higher and 110°C or lower. If it is 70°C or higher and 105°C or lower, the life at room temperature of the fiber-reinforced molding material is long, and since it can be cured in a short time (within 5 minutes) by heating, it is preferable. By using it in the fiber-reinforced molding material of the present invention, curability and moldability are more excellent. Examples of such polymerization initiators include 1,6-bis(t-butylperoxycarbonyloxy)hexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-amylperoxy)cyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, t-butylperoxydiethylacetate, t-butylperoxyisopropyl carbonate, t-butylperoxy 2-ethylhexyl carbonate, t-amylperoxyisopropyl carbonate, t-amylperoxy 2-ethylhexyl carbonate, t-hexylperoxyisopropyl carbonate, di-tert-butylperoxyhexahydroterephthalate, t-amylperoxytri-methylhexanoate, t-amylperoxyisononanoate, t-hexylperoxy-2-ethylhexanoate, n-butyl 4,4-di(t-butylperoxy)valerate, and the like. Depending on the molding conditions, an optimum organic peroxide is selected and used.

[0044] Depending on the type of resin used and the shape of the molded article to be produced, a photoinitiator may be used in combination with the polymerization initiator (C). A photoinitiator is a polymerization initiator that generates radicals by light irradiation, and a known photoinitiator can be used without particular limitation. As the photoinitiator, since it is easily available, an alkylphenone-based radical initiator, a benzophenone-based radical initiator, a benzoin-based radical initiator, an acylphosphine oxide-based radical initiator, etc. are preferable. It is also possible to use only a photoinitiator without using an organic peroxide, and it can be appropriately selected.

[0045] As the addition amount of the polymerization initiator (C), a range of 0.5 to 5 parts by mass is preferable with respect to 100 parts by mass in total of the urethane (meth) acrylate resin (A) and the (meth) acrylate monomer (B) because both the curing characteristics and the storage stability are excellent.

[0046] The curable resin composition of the present embodiment can contain components other than the urethane (meth) acrylate resin (A), the (meth) acrylate monomer (B), and the polymerization initiator (C). For example, it can contain a thermosetting resin, a thermoplastic resin, a polymerization inhibitor, a curing accelerator, a filler, a low shrinkage agent, a release agent, a thickener, a viscosity reducer, a pigment, an antioxidant, a plasticizer, a flame retardant, an antibacterial agent, an ultraviolet stabilizer, a reinforcing material, etc.

[0047] Examples of the thermosetting resin include a vinyl ester resin, an unsaturated polyester resin, a phenol resin, a melamine resin, a furan resin, a bismaleimide resin, etc. Further, these thermosetting resins can be used alone or in combination of two or more.

[0048] Examples of the thermoplastic resin include a polyamide resin, a polyethylene terephthalate resin, a polybutylene terephthalate resin, a polycarbonate resin, a polyurethane resin, a polypropylene resin, a polyethylene resin, a polystyrene resin, an acrylic resin, a polybutadiene resin, a polyisoprene resin, and those modified by copolymerization or the like. Among these, a polyamide resin and a polyurethane resin are preferable because of their high effect of improving brittleness. Further, these thermoplastic resins can be used alone or in combination of two or more. Also, the thermoplastic resin can be added and used in a particulate form or melted and mixed for use. When using a particulate thermoplastic resin, from the viewpoint of dispersibility in fibers, the particle size is preferably 30 μm or less, more preferably 5 to 20 μm.

[0049] Examples of the polymerization inhibitor include hydroquinone, trimethylhydroquinone, p-t-butylcatechol, t-butylhydroquinone, toluhydroquinone, p-benzoquinone, naphthoquinone, hydroquinone monomethyl ether, phenothiazine, copper naphthenate, copper chloride, etc. These polymerization inhibitors can be used alone or in combination of two or more.

[0050] Examples of the curing accelerator include metal soaps such as cobalt naphthenate, cobalt octenoate, vanadyl octenoate, copper naphthenate, barium naphthenate, and metal chelate compounds such as vanadyl acetylacetate, cobalt acetylacetate, iron acetylacetonate. Examples of amines include N,N-dimethylamino-p-benzaldehyde, N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethyl-p-toluidine, N-ethyl-m-toluidine, triethanolamine, m-toluidine, diethylenetriamine, pyridine, phenylmorpholine, piperidine, diethanolaniline, etc. These curing accelerators can be used alone or in combination of two or more.

[0051] Examples of the filler include inorganic compounds and organic compounds, which can be used to adjust physical properties such as the strength, elastic modulus, impact strength, and fatigue durability of the molded product.

[0052] Examples of the inorganic compound include calcium carbonate, magnesium carbonate, barium sulfate, mica, talc, kaolin, clay, celite, asbestos, barite, baryta, silica, silica sand, dolomite limestone, gypsum, aluminum fine powder, hollow balloon, alumina, glass powder, aluminum hydroxide, gypsum stone, zirconium oxide, antimony trioxide, titanium oxide, molybdenum dioxide, iron powder, etc.

[0053] Examples of the organic compound include natural polysaccharide powders such as cellulose and chitin, and synthetic resin powders. Examples of the synthetic resin powder include powders of organic substances composed of hard resins, soft rubbers, elastomers or polymers (copolymers), and particles having a multilayer structure such as a core-shell type. Specifically, examples include particles composed of acrylic particles, polyamide particles, butadiene rubber and / or acrylic rubber, urethane rubber, silicone rubber, etc., polyimide resin powder, fluororesin powder, phenol resin powder, etc. These fillers can be used alone or in combination of two or more.

[0054] Examples of the release agent include zinc stearate, calcium stearate, paraffin wax, polyethylene wax, carnauba wax, etc. Preferably, paraffin wax, polyethylene wax, carnauba wax, etc. are mentioned. These release agents can be used alone or in combination of two or more.

[0055] Examples of the thickener include metal oxides and metal hydroxides such as magnesium oxide, magnesium hydroxide, calcium oxide, calcium hydroxide, etc., and acrylic resin-based fine particles, etc., which can be appropriately selected according to the handleability of the fiber-reinforced molding material of the present embodiment. These thickeners can be used alone or in combination of two or more.

[0056] The fiber-reinforced molding material according to the embodiment of the present invention is characterized by containing the above-mentioned curable resin composition and reinforcing fiber (D). The fiber-reinforced molding material is preferably a prepreg.

[0057] Examples of the reinforcing fiber (D) include carbon fiber, glass fiber, basalt fiber, silicon carbide fiber, alumina fiber, boron fiber, metal fiber, aramid fiber, vinylon fiber, tetron fiber, organic fibers such as cellulose fiber, etc. However, since a molded product with higher strength and higher elasticity can be obtained, carbon fiber or glass fiber, basalt fiber is preferable, and carbon fiber is more preferable. These reinforcing fibers (D) can be used alone or in combination of two or more.

[0058] As the carbon fiber, various types such as polyacrylonitrile-based, pitch-based, and rayon-based can be used. Among these, polyacrylonitrile-based carbon fiber is preferred because high-strength carbon fiber can be easily obtained.

[0059] The shape of the reinforcing fiber (D) is not particularly limited, and examples include a reinforcing fiber tow in which reinforcing fiber filaments are converged, a unidirectional material in which reinforcing fiber tows are aligned in one direction, a woven fabric, a reinforcing fiber cut short, or a non-woven fabric or paper made of a reinforcing fiber cut short. However, it is preferable to use a unidirectional material as the reinforcing fiber because high mechanical properties can be obtained by laminating and molding.

[0060] When using a reinforcing fiber cut short, it is preferable to use carbon fiber cut to 2.5 to 50 mm because the fluidity in the mold during molding and the appearance of the molded product are further improved.

[0061] In the case of a woven fabric, examples include a plain weave, twill weave, damask weave, or a stitching sheet stitched so as not to loosen a sheet in which fiber bundles are aligned in one direction or a sheet laminated at an angle, such as a non-crimp fabric.

[0062] The basis weight (weight per 1 m 2 of fiber) of the reinforcing fiber is not particularly limited, but 10 g / m 2 to 650 g / m2 is preferable. A basis weight of 10 g / m 2 or more is preferable because the unevenness in fiber width is small and the mechanical properties are good. A basis weight of 650 g / m 2 or less is preferable because the impregnation of the resin is good. This basis weight is more preferably 50 to 500 g / m 2 and particularly preferably 50 to 300 g / m 2 .

[0063] In the fiber-reinforced molding material of the present embodiment, the content of the reinforcing fiber (D) is preferably in the range of 20 to 85% by mass, more preferably in the range of 40 to 80% by mass, since the mechanical strength of the obtained molded product is further improved.

[0064] The fiber-reinforced molding material of the present embodiment can be obtained, for example, by impregnating the reinforcing fiber (D) with a resin solution obtained by mixing the polyisocyanate (a1), the polyol (a2) having an amino acid skeleton, the hydroxyalkyl (meth)acrylate (a3), the (meth)acrylate monomer (B), and the polymerization initiator (C) using a known mixer such as a planetary mixer or a kneader.

[0065] Specifically, first, using a known mixer such as a planetary mixer or a kneader, A composition obtained by mixing the polyisocyanate (a1), the polyol (a2) having an amino acid skeleton, the hydroxyalkyl (meth)acrylate (a3), the (meth)acrylate monomer (B), and the polymerization initiator (C) is prepared. The composition immediately after mixing is applied onto the upper surface of a polyethylene terephthalate film subjected to a release treatment (hereinafter abbreviated as "release PET film"). After impregnating the composition into the reinforcing fiber (D), another release PET film is placed on its upper surface and sandwiched, and then rolled by a rolling mill to obtain a sheet (Step 1). The obtained sheet is allowed to stand at room temperature to 50°C to react the isocyanate group of the polyisocyanate (a1) with the hydroxy group of the polyol (a2) having an amino acid skeleton and the hydroxyalkyl (meth)acrylate (a3) (urethane-forming reaction) to produce a urethane (meth)acrylate (A) (Step 2), whereby the fiber-reinforced molding material of the present embodiment can be obtained. In Step 1, a resin solution in which the polyisocyanate (a1), the polyol (a2) having an amino acid skeleton, and the hydroxyalkyl (meth)acrylate (a3) are partially reacted in advance may be used as long as the impregnability to the reinforcing fiber (D) is not impaired.

[0066] The thickness of the fiber-reinforced molding material of this embodiment is preferably 0.02 to 1.0 mm. A thickness of 0.02 mm or more is preferable because it facilitates handling for lamination, and a thickness of 1 mm or less is preferable because resin impregnation is good. More preferably, it is 0.05 to 0.5 mm.

[0067] As a method for obtaining a molded product from the fiber-reinforced molding material obtained above, for example, the fiber-reinforced molding material is peeled from the release PET film, 8 to 30 sheets of the fiber-reinforced molding material are laminated, and then it is put into a mold preheated to 110°C to 160°C, the mold is clamped with a compression molding machine, the fiber-reinforced molding material is shaped, and the fiber-reinforced molding material is cured by maintaining a molding pressure of 0.1 to 10 MPa, and then the molded product is taken out to obtain a molded product. At this time, a manufacturing method of heat compression molding while maintaining a molding pressure of 1 to 8 MPa for a specified time of 1 to 3 minutes per 1 mm of the thickness of the molded product at a mold temperature of 130°C to 160°C in a mold having a shear edge is preferable.

[0068] The molded product obtained from the fiber-reinforced molding material of this embodiment is excellent in flexural strength, interlaminar shear strength, etc., and thus can be suitably used for automotive members, railway vehicle members, aerospace members, ship members, housing equipment members, sports members, light vehicle members, architectural civil engineering members, housings of OA equipment, etc.

Examples

[0069] The present invention will be described in more detail below with specific examples.

[0070] (Synthesis Example 1: Production of polyol (a2-1) having an amino acid skeleton) In a 0.5 L flask equipped with a thermometer, a nitrogen inlet tube, and a stirrer, 117 g of L-valine, 185 g of ethylene carbonate, and 0.3 g of tetrabutylphosphonium bromide were placed, and the temperature was raised from room temperature to 80 °C by heating. After confirming that they had dissolved, stirring was started. After raising the temperature to 120 °C while paying attention to foaming, it was held for 2 hours. Then, after raising the temperature to 130 °C, it was held for 24 hours. After confirming that the contents in the flask became transparent and there was no solid matter, the acid value was measured and it was 0 KOH mg / g. Then, it was cooled to 60 °C and the contents were taken out. The obtained compound was liquid at room temperature, and the hydroxyl value was 561 mg KOH / g. The yield was 86% based on the theoretical yield. From the above yield, it is clear that the amount of waste is less compared to the production method described in Non-Patent Document 1 above.

[0071] (Synthesis Example 2: Production of polyol (a2-2) having an amino acid skeleton) 165 g of L-phenylalanine, 185 g of ethylene carbonate, and 0.35 g of tetrabutylphosphonium bromide were placed in the 0.5 L flask, and the temperature was raised from room temperature to 80 °C by heating. After confirming that they had dissolved, stirring was started. After raising the temperature to 120 °C while paying attention to foaming, it was held for 2 hours. Then, after raising the temperature to 130 °C, it was held for 18 hours. After confirming that the contents in the flask became transparent and there was no solid matter, the acid value was measured and it was 0.5 KOH mg / g. Then, it was cooled to 60 °C and the contents were taken out. The obtained compound was liquid at room temperature, and the hydroxyl value was 426 mg KOH / g. The yield was 91% based on the theoretical yield.

[0072] (Synthesis Example 3: Production of polyol (a2-3) having an amino acid skeleton) 131 g of L-leucine, 185 g of ethylene carbonate, and 0.32 g of tetrabutylphosphonium bromide were placed in the 0.5 L flask By heating, the temperature was raised from room temperature to 80 °C. After confirming that they had dissolved, stirring was started. While paying attention to foaming, the temperature was raised to 120 °C and then held for 2 hours. Then, after raising the temperature to 130 °C, it was held for 21 hours. After confirming that the contents in the flask had become transparent and there was no solid matter, the acid value was measured and it was 0.8 KOHmg / g. Then, it was cooled to 60 °C and the contents were taken out. The obtained compound was liquid at room temperature and had a hydroxyl value of 510 mgKOH / g. The yield was 85% based on the theoretical yield.

[0073] (Synthesis Example 4: Production of polyol (a2-4) having an amino acid skeleton) To the 0.5 L flask, 103 g of 4-aminobutyric acid, 185 g of ethylene carbonate, and 0.29 g of tetrabutylphosphonium bromide were heated to raise the temperature from room temperature to 80 °C. After confirming that they had dissolved, stirring was started. While paying attention to foaming, the temperature was raised to 120 °C and then held for 2 hours. Then, after raising the temperature to 130 °C, it was held for 6 hours. After confirming that the contents in the flask had become transparent and there was no solid matter, the acid value was measured and it was 0 KOHmg / g. Then, it was cooled to 60 °C and the contents were taken out. The obtained compound was liquid at room temperature and had a hydroxyl value of 561 mgKOH / g. The yield was 90% based on the theoretical yield.

[0074] (Example 1: Production and evaluation of resin composition and prepreg (1)) 20 parts by mass of polyol (a2-1) having an amino acid skeleton obtained in Synthesis Example 1 (reaction product of L-valine and ethylene carbonate, hydroxyl equivalent 100), 26 parts by mass of 2-hydroxyethyl (meth)acrylate (a3-1), 15 parts by mass of (meth)acrylate monomer (B-1) (isobornyl methacrylate), 0.04 part by mass of parabenzoquinone, and 1 part by mass of polymerization initiator (C-1) ("Trigonox 122-C80" manufactured by Kayaku Akzo Co., Ltd., organic peroxide) were mixed. Then, 50 parts by mass of polyisocyanate (a1-1) (2,4'-diphenylmethane diisocyanate) was mixed to prepare a resin composition (X-1).

[0075] After applying the obtained resin composition (X-1) to one side of a release PET film, carbon fiber (D-1) (manufactured by Mitsubishi Rayon Co., Ltd., "TRK979PQRW") was placed on the resin composition (X-1), impregnated so that the carbon fiber content became 60% by mass, and then another release PET film was placed on and sandwiched over its upper surface. After that, it was heated at 45 °C for 24 hours and then left standing at room temperature for 3 days for storage to obtain a prepreg (1) as a fiber-reinforced molding material. The thickness of the obtained prepreg (1) was 0.25 mm.

[0076] [Fabrication of Molded Product] After cutting the obtained prepreg (1) into a width of 298 mm and a length of 218 mm, it was peeled off from the release PET film, and 8 sheets were stacked so that the fiber directions were the same to obtain a laminate. The obtained laminate was filled in the center of a flat sheet metal mold coated with a release agent once, and compression molding was performed with a compression molding machine under the conditions of a pressure of 4 MPa, an upper mold temperature of 140 °C, a lower mold temperature of 135 °C, and a molding time of 3 minutes. After opening the mold, a rubber suction cup with a diameter of 100 mm was used for demolding by air blowing into the mold. After performing a cleaning operation, it was sandwiched between stainless steel plates weighing 5 kg and cooled. Thus, a flat plate-shaped molded product (1) with a width of 300 mm, a length of 220 mm, and a thickness of 2 mm was obtained. For the release agent, a 10-fold dilution of Daifree GW-251 (manufactured by Daikin) with distilled water was used.

[0077] [Evaluation of Flexural Strength] From the obtained molded product (1), test pieces with a width of 15 mm and a length of 100 mm were cut out, and the flexural strength was measured according to JIS K7074 and evaluated according to the following criteria. 〇: 1300 MPa or more △: 1200 MPa or more and less than 1300 MPa ×: Less than 1200 MPa [Evaluation of Interlaminar Shear Strength] From the obtained molded product (1), test pieces with a width of 10 mm and a length of 22 mm were cut out, and for these test pieces, the interlaminar shear strength was measured according to JIS K7078 and evaluated according to the following criteria. 〇: 80 MPa or more △: Above 70 MPa and less than 80 MPa ×: Less than 70 MPa [Evaluation of heat resistance] From the obtained molded product (1), a test piece with a width of 10 mm and a length of 55 mm was cut out, and using "RSA-G2" manufactured by TA Instruments, the dynamic viscoelasticity was measured in the temperature range of 10 to 200 °C at a measurement frequency of 1 Hz, a heating rate of 5 °C / min, and a three-point bending mode. In the storage modulus E', the intersection of the approximate straight line in the glass region and the tangent line in the transition region was defined as the glass transition temperature (Tg), and the heat resistance was evaluated according to the following criteria. ○: 100 °C or higher △: 90 °C or higher and less than 100 °C ×: Less than 90 °C

[0078] (Example 2: Production and evaluation of resin composition and prepreg (2)) In this example, a resin composition (X-2) was prepared in the same manner as in Example 1, except that 26 parts by mass of the polyol (a2-2) having an amino acid skeleton obtained in Synthesis Example 2 was used instead of 20 parts by mass of the polyol (a2-1) having an amino acid skeleton. Then, a prepreg (2) and a molded product (2) were produced in the same manner as in Example 1, except that the obtained resin composition (X-2) was used, and the above evaluation was performed.

[0079] (Example 3: Production and evaluation of resin composition and prepreg (3)) In this example, a resin composition (X-3) was prepared in the same manner as in Example 1, except that 22 parts by mass of the polyol (a2-3) having an amino acid skeleton obtained in Synthesis Example 3 was used instead of 20 parts by mass of the polyol (a2-1) having an amino acid skeleton. Then, a prepreg (3) and a molded product (3) were produced in the same manner as in Example 1, except that the obtained resin composition (X-3) was used, and the above evaluation was performed.

[0080] (Example 4: Production and evaluation of resin composition and prepreg (4)) In this example, a resin composition (X-4) was prepared in the same manner as in Example 1, except that 20 parts by mass of the polyol (a2-4) having an amino acid skeleton obtained in Synthesis Example 4 was used instead of 20 parts by mass of the polyol (a2-1) having an amino acid skeleton. Then, a prepreg (4) and a molded article (4) were produced in the same manner as in Example 1, except that the obtained resin composition (X-4) was used, and the above evaluations were performed.

[0081] (Comparative Example 1: Preparation and Evaluation of Resin Composition (R1) and Prepreg (RX1)) In this comparative example, a polyol (ar-1) having no amino acid skeleton (Nippon Emulsion Co., Ltd. "BA-3U", ethylene oxide adduct of bisphenol A, hydroxyl equivalent 178) was used instead of the polyols (a2-1) to (a2-4) having an amino acid skeleton. 26 parts by mass of the polyol (ar-1) having no amino acid skeleton and 20 parts by mass of 2-hydroxyethyl (meth)acrylate (a3-1) were premixed at 80°C and cooled to room temperature. To the resulting solution, 15 parts by mass of ethylenically unsaturated monomer (B-1), 0.03 parts by mass of parabenzoquinone, and 1.0 part by mass of polymerization initiator (C-1) were mixed, and then 38 parts by mass of polyisocyanate (a1-1) was mixed to prepare a resin composition (RX-1). Then, a prepreg (R1) and a molded article (R1) were produced in the same manner as in Example 1, except that the obtained resin composition (RX-1) was used, and the above evaluations were performed.

[0082] The above evaluation results for the obtained molded articles (1) to (4) and (R1) are shown in Table 1.

[0083]

Table 1

[0084] The molded articles (1) to (4) of Examples 1 to 4 are all molded articles produced using a prepreg containing a curable resin composition using at least one amino acid as a raw material and reinforcing fibers. As shown in Table 1, the molded articles (1) to (4) of Examples 1 to 4 are excellent in heat resistance and are excellent in flexural strength and interlaminar shear strength as compared with the molded article (RX-1) of Comparative Example 1. Further, the molded articles (3) of Examples 1 to 3 are more excellent in interlaminar shear strength than the molded article (4) of Example 4.

Claims

1. A curable resin composition containing a urethane (meth)acrylate resin (A), a (meth)acrylate monomer (B), and a polymerization initiator (C), wherein the urethane (meth)acrylate (A) is a reaction product of a polyisocyanate (a1), a polyol (a2) having an amino acid skeleton, and a hydroxyalkyl (meth)acrylate (a3), the polyol (a2) having an amino acid skeleton is a reaction product of an amino acid and a cyclic carbonate compound. A curable resin composition characterized by this.

2. The curable resin composition according to claim 1, wherein the amino acid is one or more amino acids selected from the group consisting of an amino acid having a hydrophobic side chain, an amino acid having a carboxyl group in the side chain and a protecting group in the carboxyl group of the side chain, an amino acid having an amino group in the side chain and a protecting group in the amino group of the side chain, an amino acid having an alcoholic hydroxy group in the side chain and a protecting group in the hydroxy group of the alcoholic hydroxy group, and an amino acid having a phenolic hydroxy group in the side chain and a protecting group in the hydroxy group of the phenolic hydroxy group.

3. The amino acid is the amino acid having the hydrophobic side chain, The curable resin composition according to claim 2, wherein the amino acid having the hydrophobic side chain is an α-amino acid having an alkyl group or an aromatic skeleton in the side chain.

4. The curable resin composition according to claim 1 or 2, wherein the cyclic carbonate compound is one or more carbonate compounds selected from the group consisting of ethylene carbonate, propylene carbonate, and glycerin carbonate.

5. A fiber-reinforced molding material characterized by containing the curable resin composition according to claim 1 or 2 and a reinforcing fiber (D).

6. A molded article characterized by using the fiber-reinforced molding material according to claim 5.

7. A polyol having an amino acid skeleton and being a reaction product of an amino acid and a cyclic carbonate compound.

8. A method for producing a polyol, wherein an amino acid and a cyclic carbonate compound are mixed and heated at a temperature of 100 to 150 ° C. under solvent-free conditions until the acid value becomes 1 KOH mg / g or less to obtain a polyol having an amino acid skeleton.

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