WO2020213414A1

WO2020213414A1 - Fiber-reinforced molding material and molded article using the same

Info

Publication number: WO2020213414A1
Application number: PCT/JP2020/015167
Authority: WO
Inventors: 佳浩安谷; 健一濱田; 一迅人見
Original assignee: Dic株式会社
Priority date: 2019-04-16
Filing date: 2020-04-02
Publication date: 2020-10-22
Also published as: JPWO2020213414A1

Abstract

A fiber-reinforced molding material having as essential ingredients thereof a vinyl ester resin (A), an unsaturated monomer (B) having a flash point of at least 100°C, a polyisocyanate (C), a polymerization initiator (D), and carbon fiber (E) having a fiber length of 2.5–50 mm. The fiber-reinforced molding material is characterized by the ratio (3,490 cm^-1/3,340 cm^-1) between the transmittance at 3,490 cm^-1 and 3,340 cm^-1 in a FT–IR ATR measurement being 1.01–1.06. This fiber-reinforced molding material has excellent handling and flexibility, including the work environment during molding work, molding material film peeling characteristics, and tackiness, and molded articles having excellent physical properties such as bending strength, etc., can be obtained. As a result, this molding material can be suitably used in automobile members, railway vehicle members, aerospace machinery members, ship members, housing equipment members, sports members, non-motorized vehicle members, construction and civil engineering members, and cases for OA devices, etc.

Description

Fiber reinforced molding material and molded products using it

The present invention relates to a fiber reinforced molding material and a molded product thereof.

Fiber-reinforced resin composite materials reinforced with thermosetting resins such as epoxy resin and unsaturated polyester resin using carbon fiber as reinforced fibers are attracting attention for their excellent heat resistance and mechanical strength while being lightweight. Its use in various structural applications such as bodies and various members is expanding. As a method for molding a material using an epoxy resin in this fiber-reinforced resin composite material, an autoclave method in which a material called prepreg is heated and cured by a pressurable autoclave is known, and an unsaturated polyester resin is used. As a method for molding a material, there is known a method of curing and molding by a method such as press molding or injection molding using an intermediate material called a sheet molding compound (SMC) or a bulk molding compound (BMC). Particularly in recent years, the development of highly productive materials has been actively carried out.

Examples of such molding materials include carbon fiber reinforced sheet-like molding containing unsaturated polyester resin, vinyl monomer, thermoplastic polymer, polyisocyanate, filler, conductive carbon black and wide carbon fiber bundle as essential components. The material is known (see, for example, Patent Document 1). Although a molded product having an excellent appearance can be obtained from this molding material, since a highly volatile styrene monomer is used, the odor is strong and there is a problem in the working environment during the molding work.

In addition, since the film used for manufacturing or packing the molding material needs to be removed from the material at the time of molding, the film is required to be easily peeled off. It is known that a material in which the thickening step of the material is insufficient not only deteriorates the film peeling property but also causes a lot of burrs during molding to deteriorate the moldability. On the other hand, with a material in which the thickening process has progressed excessively, it becomes difficult to install the material along the shape of the mold or the like, and the fluidity of the material in the mold is significantly reduced during press molding or the like. Problems occur. For this reason, there has been a demand for a material that has both film peelability and appropriate flexibility of the molding material.

JP-A-2009-13306

The problem to be solved by the present invention is to obtain a molded product having excellent work environment during molding work, handleability including film peeling property and tackiness of the molding material, flexibility, and various physical properties such as bending strength. It is to provide a fiber-reinforced molding material and a molded product thereof.

The present inventors have specified fiber reinforced plastics containing vinyl ester resin, unsaturated monomer having a flammability of 100 ° C. or higher, polyisocyanate, polymerization initiator, and carbon fiber having a fiber length of 2.5 to 50 mm as essential components. The present invention has been completed by finding that a molded product having excellent working environment, handleability and flexibility, and various physical properties such as bending strength can be obtained as a molding material.

That is, vinyl ester resin (A), unsaturated monomer (B) having a ignition point of 100 ° C. or higher, polyisocyanate (C), polymerization initiator (D), and carbon fiber having a fiber length of 2.5 to 50 mm ( E) the a fiber-reinforced molding material containing, as essential raw materials, the ratio of the transmittance at 3490cm ^-1 and 3340cm ^-1 in ATR measurement of ^{FT-IR (3490cm -1 / 3340cm} -1) is 1.01 to 1 The present invention relates to a fiber-reinforced molding material having a range of .06 and a molded product using the same.

Since the molded product obtained from the fiber-reinforced molding material of the present invention is excellent in bending strength, flexural modulus, etc., automobile members, railroad vehicle members, aerospace machine members, ship members, housing equipment members, sports members, etc. It can be suitably used for light vehicle members, building civil engineering members, housings for OA equipment, and the like.

The fiber-reinforced molding material of the present invention comprises a vinyl ester resin (A), an unsaturated monomer (B) having a flammability of 100 ° C. or higher, a polyisocyanate (C), a polymerization initiator (D), and a fiber length 2. 5 ~ 50 mm carbon fiber of (E) a fiber-reinforced molding material containing, as essential raw materials, the ratio of the transmittance at 3490cm ^-1 and 3340cm ^-1 in ATR measurement of ^{FT-IR (3490cm -1 / 3340cm} -1 ) (Hereinafter, abbreviated as “transmittance ratio α”) is in the range of 1.01 to 1.06.

The transmittance of the FT-IR in the ATR measurement of the present invention is obtained from the peak value of the transmission spectrum. 3490 cm ^-1 is the peak derived from the OH bond, and 3340 cm ^-1 is derived from the NH bond. Is the peak of.

It is important that the transmittance ratio α is in the range of 1.01 to 1.06 from the viewpoint of film peelability and the balance between tackiness and flexibility, but the film peelability and tackiness are further improved. Therefore, it is preferably 1.02 or more, and more preferably 1.05 or less because the flexibility is further improved.

The vinyl ester resin (A) can be obtained by reacting the epoxy resin (a1) with the (meth) acrylic acid (a2), and has the handleability and fluidity such as film peelability and tackiness during molding. The molar ratio (COOH / EP) of the epoxy group (EP) of the epoxy resin (a1) to the carboxyl group (COOH) of the (meth) acrylic acid (a2) is 0.6 to 1 because of its excellent balance. It is preferable to react in the range of 1. From this viewpoint, the epoxy equivalent of the epoxy resin (a1) is preferably in the range of 180 to 370, more preferably in the range of 180 to 250.

In the present invention, "(meth) acrylic acid" means one or both of acrylic acid and methacrylic acid, and "(meth) acrylate" means one or both of acrylate and methacrylate.

Examples of the epoxy resin (a1) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol fluorene type epoxy resin, biscresol fluorene type and other bisphenol type epoxy resins, phenol novolac type epoxy resin, and cresol novolac type epoxy. Novolak type epoxy resin such as resin, oxodoridone modified epoxy resin, phenolic glycidyl ether such as brominated epoxy resin of these resins, dipropylene glycol diglycidyl ether, trimethylpropan triglycidyl ether, alkylene oxide adduct of bisphenol A Diglycidyl ether, glycidyl ether of polyhydric alcohols such as diglycidyl ether of bisphenol A hydride, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, 1-epociethyl- Alicyclic epoxy resin such as 3,4-epoxycyclohexane, phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, diglycidyl-p-oxybenzoic acid, glycidyl ester such as dimer acid glycidyl ester, tetraglycidyldiaminodiphenylmethane, tetra Glycidyl amines such as glycidyl-m-xylene diamine, triglycidyl-p monoaminophenol, N, N-diglycidyl aniline, heterocyclic epoxies such as 1,3-diglycidyl-5,5-dimethylhydantoin, triglycidyl isocyanurate. Examples include resin. Among these, bifunctional aromatic epoxy resins are preferable, and bisphenol A type epoxy resins and bisphenol F type epoxy resins are more preferable because they are superior in the strength of the molded product, the handleability of the molding material, and the fluidity during molding of the molding material. preferable. These epoxy resins may be used alone or in combination of two or more.

Further, the epoxy resin (a1) may be used by increasing the molecular weight with a dibasic acid such as bisphenol A in order to adjust the epoxy equivalent.

The reaction between the epoxy resin and (meth) acrylic acid described above is preferably carried out at 60 to 140 ° C. using an esterification catalyst. Further, a polymerization inhibitor or the like can also be used.

It is important that the unsaturated monomer (B) has a flash point of 100 ° C. or higher. As a result, the odor during the molding work can be suppressed, and the work environment is excellent. Further, since the unsaturated monomer has a high boiling point, it has excellent moldability during high-temperature molding, enables high-temperature single-hour molding, and improves productivity.

The flash point in the present invention is the flash point measured by the Cleveland opening method specified in JIS K2265-4: 2007.

Examples of the unsaturated monomer (B) include benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate alkyl ether, and polypropylene glycol (meth) acrylate. Alkyl ether, 2-ethylhexyl methacrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, isotridecyl (meth) acrylate, n-stearyl (meth) acrylate, tetrahydrofurfuryl methacrylate, isobornyl (meth) acrylate, dicyclopentenyloxyethyl Monofunctional (meth) acrylate compounds such as (meth) acrylate and dicyclopentanyl methacrylate; ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1, 3-Butandiol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, bisphenol di (meth) acrylate, 1,4-cyclohexanedimethanol di (meth) acrylate Di (meth) acrylate compounds such as, diallyl phthalate, divinyl benzene, etc. Among these, unsaturated monomers having an aromatic are preferable because a molding material having higher strength can be obtained, and benzyl methacrylate. , Phenoxyethyl methacrylate is more preferred. In addition, these unsaturated monomers can be used alone or in combination of two or more.

The mass ratio ((A) / (B)) of the vinyl ester resin (A) to the unsaturated monomer (B) is determined by the resin impregnation property, handleability (tack property) and curability of the carbon fibers. The range of 40/60 to 85/15 is preferable, and the range of 50/50 to 70/30 is more preferable, because the balance is further improved.

The viscosity of the mixture of the vinyl ester resin (A) and the unsaturated monomer (B) is
The range of 200 to 8,000 mPa · s (25 ° C.) is preferable because the resin impregnation property of the carbon fiber is further improved.

The polyisocyanate (C) is, for example, a diphenylmethane diisocyanate (4,4'-form, 2,4'-form, or 2,2'-form, or a mixture thereof), a carbodiimide-modified product of diphenylmethane diisocyanate, or a nurate-modified product. Diphenylmethane diisocyanate modified product such as body, bullet modified product, urethane imine modified product, polyol modified product modified with polyol having a number average molecular weight of 1,000 or less such as diethylene glycol and dipropylene glycol, tolylene diisocyanate, trizine diisocyanate, polymethylene poly Aromatic polyisocyanates such as phenyl polyisocyanate, xylylene diisocyanate, 1,5-naphthalenediocyanate, tetramethylxylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, norbornene diisocyanate; Hexamethylene diisocyanate, a nurate-modified product of hexamethylene diisocyanate, a bullet-modified product, an adduct-isocyanate, an aliphatic polyisocyanate such as diisocyanate dimerate, or the like can be used. Among these, aromatic polyisocyanates are preferable because a molding material having excellent handleability (film peelability / tackiness) can be obtained. In addition, these polyisocyanates (C) can be used alone or in combination of 2 or more types.

The molar ratio (NCO / OH) of the isocyanate group (NCO) of the polyisocyanate (C) to the hydroxyl group (OH) of the vinyl ester resin (A) has a transmittance ratio α of 1.01 to 1.06. Since the range can be easily controlled, the range of 0.5 to 0.95 is preferable, and further, the balance between handleability (film peeling property and tackiness) and flexibility is more excellent, so 0.55 to 0. 85 is more preferable.

The polymerization initiator (D) is not particularly limited, but an organic peroxide is preferable, and for example, a diacyl peroxide compound, a peroxy ester compound, a hydroperoxide compound, a ketone peroxide compound, an alkyl perester compound, and a par. Examples thereof include carbonate compounds and peroxyketal, which can be appropriately selected depending on the molding conditions. In addition, these polymerization initiators (D) can be used alone or in combination of two or more.

Among these, it is preferable to use a polymerization initiator having a temperature of 70 ° C. or higher and 110 ° C. or lower for obtaining a 10-hour half-life for the purpose of shortening the molding time. When the temperature is 70 ° C. or higher and 110 ° C. or lower, the life of the fiber-reinforced molding material at room temperature is long, and it can be cured in a short time by heating, which is preferable, and the balance between curability and moldability is more excellent. Examples of such a polymerization initiator include 1,6-bis (t-butylperoxycarbonyloxy) hexane, 1,1-bis (t-butylperoxy) cyclohexane, and 1,1-bis (t-). Amylperoxy) cyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, t-butylperoxydiethylacetate, t-butylperoxyisopropyl carbonate, t-amylperoxyisopropylcarbonate, t-hexylperoxyisopropyl Examples thereof include carbonate, di-tert-butylperoxyhexahydroterephthalate, t-amylperoxytrimethylhexanoate and the like.

The content of the polymerization initiator (D) is 0 with respect to the total amount of the vinyl ester resin (A) and the unsaturated monomer (B) because both the curing characteristics and the storage stability are excellent. The range of 3 to 3% by mass is preferable.

As the carbon fiber (E), a carbon fiber cut to a length of 2.5 to 50 mm is used, but since the fluidity in the mold at the time of molding, the appearance of the molded product and the mechanical properties are further improved. Carbon fibers cut to 5 to 40 mm are more preferable.

As the carbon fiber (E), various types such as polyacrylonitrile-based, pitch-based, rayon-based, etc. can be used, but among these, polyacrylonitrile-based ones because high-strength carbon fibers can be easily obtained. Is preferable.

Further, the number of filaments of the fiber bundle used as the carbon fiber (E) is preferably 1,000 to 60,000 because the resin impregnation property and the mechanical physical properties of the molded product are further improved.

The content of the carbon fiber (E) in the components of the fiber-reinforced molded material of the present invention is preferably in the range of 20 to 80% by mass, preferably 40 to 80%, because the mechanical properties of the obtained molded product are further improved. The range of 70% by mass is more preferable. If the carbon fiber content is low, a high-strength molded product may not be obtained, and if the carbon fiber content is high, the resin impregnation property of the fibers is insufficient, causing swelling of the molded product, which is also high. There is a possibility that a strong molded product cannot be obtained.

Further, the carbon fiber (E) in the fiber-reinforced molding material of the present invention is impregnated with the resin in a state where the fiber direction is random.

The components of the fiber-reinforced molding material of the present invention include the vinyl ester resin (A), the unsaturated monomer (B), the polyisocyanate (C), the polymerization initiator (D), and the carbon fiber (E). ) May be used, for example, a thermosetting resin other than the vinyl ester resin (A), a thermoplastic resin, a polymerization inhibitor, a curing accelerator, a filler, a low shrinkage agent, a mold release agent, etc. It can contain a thickener, a thickener, a pigment, an antioxidant, a plasticizer, a flame retardant, an antibacterial agent, an ultraviolet stabilizer, a reinforcing material, a photocuring agent and the like.

Examples of the thermosetting resin include vinyl urethane resin, unsaturated polyester resin, acrylic resin, epoxy resin, phenol resin, melamine resin, furan resin and the like. In addition, these thermosetting resins can be used alone or in combination of two or more.

Examples of the thermoplastic resin include polyamide resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polycarbonate resin, urethane resin, polypropylene resin, polyethylene resin, polystyrene resin, acrylic resin, polybutadiene resin, polyisoprene resin, and copolymerization thereof. Examples thereof include those modified by the above. In addition, these thermoplastic resins can be used alone or in combination of two or more.

Examples of the polymerization inhibitor include hydroquinone, trimethylhydroquinone, pt-butylcatechol, t-butylhydroquinone, toluhydroquinone, p-benzoquinone, naphthoquinone, hydroquinone monomethyl ether, phenothiazine, copper naphthenate, copper chloride and the like. Be done. These polymerization inhibitors may be used alone or in combination of two or more.

Examples of the curing accelerator include metal soaps such as cobalt naphthenate, cobalt octate, vanazyl octate, copper naphthenate, and barium naphthenate, and metal chelates such as vanadylacetyl acetate, cobalt acetylacetate, and iron acetylacetonate. Examples include compounds. As amines, N, N-dimethylamino-p-benzaldehyde, N, N-dimethylaniline, N, N-diethylaniline, N, N-dimethyl-p-toluidine, N-ethyl-m-toluidine, triethanol Examples include amines, m-toluidine, diethylenetriamine, pyridine, phenylmorpholine, piperidine, diethanolaniline and the like. These curing accelerators can be used alone or in combination of two or more.

The filler includes inorganic compounds and organic compounds, which can be used to adjust physical properties such as strength, elastic modulus, impact strength, and fatigue durability of molded products.

Examples of the inorganic compound include calcium carbonate, magnesium carbonate, barium sulfate, mica, talc, kaolin, clay, celite, asbestos, burlite, baryta, silica, silica sand, dolomite limestone, gypsum, aluminum fine powder, hollow balloon, and the like. Examples thereof include alumina, glass powder, aluminum hydroxide, cold water stone, zirconium oxide, antimony trioxide, titanium oxide, molybdenum dioxide, and iron powder.

Examples of the organic compound include natural polysaccharide powders such as cellulose and chitin, synthetic resin powders, and the like, and synthetic resin powders are composed of hard resins, soft rubbers, elastomers, polymers (copolymers), and the like. Particles having a multilayer structure such as organic powder or core-shell type can be used. Specific examples thereof include particles made of butadiene rubber and / or acrylic rubber, urethane rubber, silicon rubber and the like, polyimide resin powder, fluororesin powder, phenol resin powder and the like. These fillers can be used alone or in combination of two or more.

Examples of the release agent include zinc stearate, calcium stearate, paraffin wax, polyethylene wax, carnauba wax and the like. Preferably, paraffin wax, polyethylene wax, carnauba wax and the like can be mentioned. These release agents may be used alone or in combination of two or more.

Examples of the thickener include metal oxides such as magnesium oxide, magnesium hydroxide, calcium oxide and calcium hydroxide, acrylic resin-based fine particles such as metal hydroxides, and the fiber-reinforced molding material of the present invention. It can be selected as appropriate depending on the handleability of. These thickeners can be used alone or in combination of two or more.

The fiber-reinforced molding material of the present invention is a sheet molding compound (hereinafter abbreviated as "SMC") or a bulk molding compound (hereinafter, "BMC") from the viewpoint of excellent productivity and moldability having design diversity. It is abbreviated as).

As a method for producing the SMC, the vinyl ester resin (A) and the unsaturated monomer (B) are produced by using a mixer such as an ordinary mixer, an intermixer, a planetary mixer, a roll, a kneader, or an extruder. , The polyisocyanate (C), the polymerization initiator (D) and the like are mixed and dispersed, and the obtained resin composition is applied to the carrier films placed on the upper and lower sides so as to have a uniform thickness. , The carbon fiber (E) is sandwiched between the resin compositions on the carrier films installed above and below, and then the whole is passed between the impregnated rolls and pressure is applied to the carbon fiber (E). After impregnating the resin, a method of winding it into a roll or folding it into a zigzag fold can be mentioned. Further, after this, it is preferable to carry out aging at a temperature of 10 to 60 ° C. for 2 to 48 hours.

In the aging step, it is important to control the reaction between the vinyl ester resin (A) and the polyisocyanate (C). For example, by sealing the molding material with a metal-deposited film or the like, moisture or the like can be obtained. The side reaction of the above can be suppressed, and the transmittance ratio α of the molded material after aging can be controlled in the range of 1.01 to 1.06.

As the carrier film, polyethylene film, polypropylene film, polyethylene and polypropylene laminated film, polyethylene terephthalate, nylon and the like can be used.

As the method for producing the BMC, the vinyl ester resin (A) can be produced by using a mixer such as a normal mixer, an intermixer, a planetary mixer, a roll, a kneader, or an extruder, as in the method for producing the SMC. Each component such as the unsaturated monomer (B), the polyisocyanate (C), and the polymerization initiator (D) is mixed and dispersed, and the carbon fiber (E) is mixed with the obtained resin composition. Examples include a method of dispersing. Further, after this, it is preferable to mature in the same manner as SMC.

The molded product of the present invention can be obtained from the fiber-reinforced molding material, but from the viewpoint of excellent productivity and excellent design diversity, heat compression molding of SMC or BMC is preferable as the molding method.

In the heat compression molding, for example, a predetermined amount of a molding material such as SMC or BMC is weighed, put into a mold preheated to 110 to 180 ° C., molded by a compression molding machine, and the molding material is applied. A manufacturing method is used in which a molding material is cured by molding and holding a molding pressure of 0.1 to 30 MPa, and then the molded product is taken out to obtain a molded product. As specific molding conditions, molding conditions in which the molding pressure of 1 to 15 MPa is maintained in the mold at a mold temperature of 120 to 160 ° C. for 1 to 5 minutes per 1 mm of thickness of the molded product is preferable, and the productivity is good. It is more preferable that the molding conditions are such that the molding pressure of 1 to 15 MPa is maintained for 1 to 3 minutes per 1 mm of the thickness of the molded product at a mold temperature of 140 to 160 ° C.

Since the molded product obtained from the fiber-reinforced molded material of the present invention is excellent in appearance, bending strength, flexural modulus, etc., it is an automobile member, a railroad vehicle member, an aerospace machine member, a ship member, a housing equipment member, a sports member. , Light vehicle members, building civil engineering members, housings for OA equipment, etc. can be suitably used.

The present invention will be described in more detail below with specific examples. The hydroxyl value of potassium hydroxide required to neutralize acetic acid produced when 1 g of a resin sample was reacted at a specified temperature and time using an acetylating agent based on the method specified in JIS K-0070. The number of milligrams (mgKOH / g) was measured.

(Synthesis Example 1: Synthesis of Vinyl Ester Resin (A-1))
In a 2L flask equipped with a thermometer, a nitrogen introduction tube, and a stirrer, 725 parts by mass of epoxy resin ("Epiclon 860" manufactured by DIC Corporation, bisphenol A type epoxy resin, epoxy equivalent 220), 284 parts by mass of methacrylic acid, and t. -Butylhydroquinone 0.28 parts by mass was charged, and the temperature was raised to 90 ° C. under a gas flow in which nitrogen and air were mixed 1: 1. When 0.60 parts by mass of 2-methylimidazole was added thereto, the temperature was raised to 110 ° C. and the reaction was carried out for 10 hours, the acid value became 6 or less, and the reaction was terminated. After cooling to around 60 ° C., the mixture was taken out from the reaction vessel to obtain a vinyl ester resin (A-1) having a hydroxyl value of 215 mgKOH / g.

(Synthesis Example 2: Synthesis of Vinyl Ester Resin (A-2))
Epoxy resin ("Epiclon 850" manufactured by DIC Corporation, bisphenol A type epoxy resin, epoxy equivalent 188) 677 parts by mass, 310 parts by mass of methacrylic acid, and t in a 2L flask equipped with a thermometer, a nitrogen introduction tube, and a stirrer. -Butylhydroquinone 0.29 parts by mass was charged, and the temperature was raised to 90 ° C. under a gas flow in which nitrogen and air were mixed 1: 1. When 0.60 parts by mass of 2-methylimidazole was added thereto, the temperature was raised to 110 ° C. and the reaction was carried out for 10 hours, the acid value became 6 or less, and the reaction was terminated. After cooling to around 60 ° C., the mixture was taken out from the reaction vessel to obtain a vinyl ester resin (A-2) having a hydroxyl value of 217 mgKOH / g.

(Synthesis Example 3: Synthesis of Vinyl Ester Resin (A-3))
656 parts by mass of epoxy resin ("Epiclon 850" manufactured by DIC Co., Ltd., bisphenol A type epoxy resin, epoxy equivalent 188), 147 parts by mass of bisphenol A, and 2 in a 2L flask equipped with a thermometer, a nitrogen introduction tube, and a stirrer. -0.4 parts by mass of methylimidazole was charged, the temperature was raised to 120 ° C. and the reaction was carried out for 3 hours, and the epoxy equivalent was measured. After confirming that the epoxy equivalent was 365 as set, after cooling to around 60 ° C., 185 parts by mass of methacrylic acid and 0.29 parts by mass of t-butyl hydroquinone were charged, and nitrogen and air were mixed 1: 1. The temperature was raised to 90 ° C. under the mixed gas flow. When 0.18 parts by mass of 2-methylimidazole was added thereto, the temperature was raised to 110 ° C. and the reaction was carried out for 10 hours, the acid value became 6 or less, and the reaction was terminated. After cooling to around 60 ° C., the mixture was taken out from the reaction vessel to obtain a vinyl ester resin (A-3) having a hydroxyl value of 209 mgKOH / g.

(Example 1: Preparation and evaluation of fiber-reinforced molding material (1))
Polyisocyanate (“Luplanate MI” manufactured by BASF, aromatic polyisocyanate) was added to 100 parts by mass of a resin solution prepared by dissolving 55 parts by mass of the vinyl ester resin (A-1) obtained in Synthesis Example 1 in 45 parts by mass of phenoxyethyl methacrylate. (Hereinafter abbreviated as "polyisocyanate (C-1)") 22.0 parts by mass, and polymerization initiator ("Kayacarboxylic AIC-75" manufactured by Chemical Axo Co., Ltd., organic peroxide; hereinafter, "polymerization" Initiator (D-1) "is abbreviated.) 1.2 parts by mass and 0.035 parts by mass of a polymerization inhibitor (parabenzoquinone; hereinafter abbreviated as polymerization inhibitor (1)) are mixed to form a resin. The composition (X-1) was obtained. The molar ratio (NCO / OH) in this resin composition (X-1) was 0.83.

The resin composition (X-1) obtained above is applied onto a polyethylene and polypropylene laminated film so that the average coating amount is 0.5 kg / m ^2, and carbon fiber roving (Toray Co., Ltd.) is applied thereto. A carbon fiber (hereinafter abbreviated as carbon fiber (E-1)) obtained by cutting a product "T700SC-12000-50C") to 25 mm has a uniform thickness and a carbon fiber content of 50% by mass without fiber directionality. The resin composition (X-1) is similarly dropped from the air so as to be uniform, sandwiched between films coated at 0.5 kg / m ² , carbon fibers are impregnated with resin, and then packed and sealed with an aluminum vapor-deposited film. Then, it was left in a constant temperature machine at 40 ° C. for 20 hours to obtain a sheet-shaped fiber-reinforced molding material (1). The basis weight of this sheet-shaped fiber-reinforced molding material (1) was 2 kg / m ² .

[Transmittance ratio α]
The fiber-reinforced molding material (1) obtained above was cut into a size of 10 mm × 10 mm, and the polyethylene-polypropylene laminate film was peeled off. The surface in contact with this film was used as the measurement surface, and the measurement was performed under the following measurement conditions, and the ratio of the transmittances at 3490 cm ^-1 and 3340 cm ^-1 was calculated.
Measuring device: "FT-IR Spectrometer Frontier T" manufactured by PerkinElmer
ATR measurement unit: "Golden Gate diamond" made by Specac
Measurement method: 1-reflection ATR method Crystal: Type IIIa diamond (2 mm x 2 mm)
ATR penetration depth (n = 1.5, 1000 cm ^-1 ): 2 um
Light source: MIR (8000-30 cm ^-1 )
Incident angle: 45 °
Detector: MIR TGS (15000-370cm ^-1 )
Measuring range: 4000-400 cm ^-1
Resolution: 4 cm ^-1
Accumulation number: 8 times

[Evaluation of handleability (film peelability)]
The peelability of the fiber-reinforced molding material (1) obtained above when peeled from the polyethylene-polypropylene laminate film at 25 ° C. was evaluated according to the following criteria.
◯: The molding material is not sticky and no deposits remain on the film.
Δ: The molding material is sticky, and some deposits remain on the film.
X: The molding material and the film are in close contact with each other, and a large amount of deposits remain on the film.

[Evaluation of handleability (tackability)]
The tackiness of the fiber-reinforced molding material (1) obtained above after being peeled from the polyethylene and polypropylene laminated film at 25 ° C. was evaluated according to the following criteria.
◯: No molding material adhered to the finger △: Molding material adhered slightly to the finger ×: Molding material adhered to the finger

[Manufacturing of molded products]
The sheet-shaped fiber-reinforced molding material (1) obtained above was peeled from the film, three pieces cut into 265 cm × 265 cm were stacked, and set in the center of a 30 × 30 cm ² flat plate mold, and pressed. Molding was performed at a mold temperature of 150 ° C., a pressing time of 5 minutes, and a pressing pressure of 12 MPa to obtain a flat molded product (1) having a thickness of 3 mm.

[Evaluation of flexibility]
◯: Can be easily installed along the shape of the mold during molding.
Δ: Slight elasticity (repulsion) works during molding, but it can be installed along the shape of the mold.
X: Strong elasticity acts during molding, and it cannot be installed along the shape of the mold.

[Evaluation of flexural strength and flexural modulus]
Five samples were cut out from the molded product (1) obtained above in the horizontal and vertical directions, and a three-point bending test was performed in accordance with JIS K7074 to measure the bending strength and flexural modulus.

(Example 2: Preparation and evaluation of fiber-reinforced molding material (2))
Polyisocyanate (“Lupranate M5S” manufactured by BASF, aromatic polyisocyanate) was added to 100 parts by mass of a resin solution prepared by dissolving 55 parts by mass of the vinyl ester resin (A-1) obtained in Synthesis Example 1 in 45 parts by mass of phenoxyethyl methacrylate. In the following, it is abbreviated as "polyisocyanate (C-2)") 17.5 parts by mass, 1.2 parts by mass of polymerization initiator (D-1), and 0.035 parts by mass of polymerization inhibitor (E-1). The parts were mixed to obtain a resin composition (X-2). The molar ratio (NCO / OH) in this resin composition (X-2) was 0.63.

(Example 3: Preparation and evaluation of fiber-reinforced molding material (3))
Polyisocyanate (“Cosmonate LL” manufactured by Mitsui Chemicals SKC Polyurethane Co., Ltd.) was added to 100 parts by mass of a resin solution prepared by dissolving 55 parts by mass of the vinyl ester resin (A-1) obtained in Synthesis Example 1 in 45 parts by mass of phenoxyethyl methacrylate. Aromatic polyisocyanate; hereinafter abbreviated as "polyisocyanate (C-3)") 21 parts by mass, polymerization initiator (D-1) 1.2 parts by mass, and polymerization inhibitor (E-1) 0. 035 parts by mass was mixed to obtain a resin composition (X-3). The molar ratio (NCO / OH) in this resin composition (X-3) was 0.68.

(Example 4: Preparation and evaluation of fiber-reinforced molding material (4))
In 100 parts by mass of a resin solution prepared by dissolving 55 parts by mass of the vinyl ester resin (A-1) obtained in Synthesis Example 1 in 45 parts by mass of phenoxyethyl methacrylate, 24 parts by mass of polyisocyanate (C-1) and a polymerization initiator ( D-1) 1.2 parts by mass and 0.035 parts by mass of the polymerization inhibitor (E-1) were mixed to obtain a resin composition (X-4). The molar ratio (NCO / OH) in this resin composition (X-4) was 0.90.

(Example 5: Preparation and evaluation of fiber-reinforced molding material (5))
In 100 parts by mass of a resin solution prepared by dissolving 55 parts by mass of the vinyl ester resin (A-1) obtained in Synthesis Example 1 in 45 parts by mass of phenoxyethyl methacrylate, 16 parts by mass of polyisocyanate (C-2) and a polymerization initiator ( D-1) 1.2 parts by mass and 0.035 parts by mass of the polymerization inhibitor (E-1) were mixed to obtain a resin composition (X-5). The molar ratio (NCO / OH) in this resin composition (X-5) was 0.57.

(Example 6: Preparation and evaluation of fiber-reinforced molding material (6))
Polymerization of polyisocyanate (C-2) was started in 100 parts by mass of a resin solution prepared by dissolving 58 parts by mass of the vinyl ester resin (A-2) obtained in Synthesis Example 2 in 42 parts by mass of phenoxyethyl methacrylate. 1.2 parts by mass of the agent (D-1) and 0.035 parts by mass of the polymerization inhibitor (E-1) were mixed to obtain a resin composition (X-6). The molar ratio (NCO / OH) in this resin composition (X-6) was 0.73.

(Example 7: Preparation and evaluation of fiber-reinforced molding material (7))
In 100 parts by mass of a resin solution prepared by dissolving 46 parts by mass of the vinyl ester resin (A-3) obtained in Synthesis Example 3 in 54 parts by mass of phenoxyethyl methacrylate, 13 parts by mass of polyisocyanate (C-1) and a polymerization initiator (polymerization initiator). D-1) 1.2 parts by mass and 0.035 parts by mass of the polymerization inhibitor (E-1) were mixed to obtain a resin composition (X-7). The molar ratio (NCO / OH) in this resin composition (X-7) was 0.61.

The same operation as in Example 1 was performed except that the resin composition (X-1) used in Example 1 was changed to the resin compositions (X-2) to (X-7), and the fiber reinforced molding material (2) was operated. )-(7) were prepared and each evaluation was performed.

(Comparative Example 1: Preparation and Evaluation of Fiber Reinforced Molding Material (R1))
In 100 parts by mass of a resin solution prepared by dissolving 55 parts by mass of the vinyl ester resin (A-1) obtained in Synthesis Example 1 in 45 parts by mass of phenoxyethyl methacrylate, 27 parts by mass of polyisocyanate (C-1) and a polymerization initiator (polymerization initiator). D-1) 1.2 parts by mass and 0.035 parts by mass of the polymerization inhibitor (E-1) were mixed to obtain a resin composition (RX-1). The molar ratio (NCO / OH) in this resin composition (RX-1) was 1.00.

(Comparative Example 2: Preparation and Evaluation of Fiber Reinforced Molding Material (R2))
In 100 parts by mass of a resin solution prepared by dissolving 55 parts by mass of the vinyl ester resin (A-1) obtained in Synthesis Example 1 in 45 parts by mass of phenoxyethyl methacrylate, 12 parts by mass of polyisocyanate (C-2) and a polymerization initiator ( D-1) 1.2 parts by mass and 0.035 parts by mass of the polymerization inhibitor (E-1) were mixed to obtain a resin composition (RX-2). The molar ratio (NCO / OH) in this resin composition (RX-2) was 0.43.

The same operation as in Example 1 was performed except that the resin composition (X-1) used in Example 1 was changed to the resin composition (RX-1) or (RX-2), and the fiber reinforced molding material (R1) was operated. ) Or (R2) was prepared and each evaluation was performed. Since the handleability was poor, the bending strength and flexural modulus of the molded product were not evaluated.

Tables 1 and 2 show the evaluation results of the fiber-reinforced molding materials (1) to (7), (R1) and (R2) obtained above.

It was confirmed that the fiber-reinforced molding materials of the present invention of Examples 1 to 7 are excellent in handleability such as film peelability and tackiness, and flexibility, and the obtained molded product is excellent in bending strength and flexural modulus. It was.

On the other hand, Comparative Example 1, although the ratio of the transmittance at 3490cm ^-1 and 3340cm ^-1 in ATR measurement of FT-IR (transmittance ratio alpha) is 1.06 greater example, that flexibility is inferior confirmed.

Comparative Example 2 is an example in which the transmittance ratio α is smaller than 1.01, but it was confirmed that the film peelability and tackiness were inferior.

Claims

Vinyl ester resin (A), unsaturated monomer (B) having a ignition point of 100 ° C. or higher, polyisocyanate (C), polymerization initiator (D), and carbon fiber (E) having a fiber length of 2.5 to 50 mm. the a fiber-reinforced molding material containing, as essential raw materials, the transmittance ratio (3490cm -1 / 3340cm -1) is 1.01 to 1.06 at 3490cm -1 and 3340cm -1 in ATR measurement of FT-IR A fiber-reinforced molding material characterized by being in the range of.
The fiber-reinforced molding material according to claim 1, wherein the vinyl ester resin (A) is a reaction product of an epoxy resin (a1) having an epoxy equivalent in the range of 180 to 370 and (meth) acrylic acid (a2).
The fiber-reinforced molding material according to claim 1 or 2, wherein the polyisocyanate (C) is an aromatic polyisocyanate.
A molded product using the fiber-reinforced molding material according to any one of claims 1 to 3.