WO2011092962A1

WO2011092962A1 - Sizing agent for carbon fiber, carbon fiber, method for producing carbon fiber, and molding material and molded article each containing carbon fiber

Info

Publication number: WO2011092962A1
Application number: PCT/JP2010/072547
Authority: WO
Inventors: 重明大角; 英彦友國
Original assignee: ディーエイチ・マテリアル株式会社
Priority date: 2010-01-28
Filing date: 2010-12-15
Publication date: 2011-08-04
Also published as: JP4856292B2; JPWO2011092962A1

Abstract

Disclosed are: a sizing agent for a carbon fiber, which is applicable to various molding methods and can be used for the production of a molded article that has a good balance between excellent strength and weight reduction; a carbon fiber which is surface-treated with the sizing agent; a method for producing the carbon fiber; and a molding material and a molded article, which contain the carbon fiber. Specifically disclosed are: a sizing agent for a carbon fiber, which contains a moisture curable polyurethane (A); a surface-treated carbon fiber (C) which has, on the surface of a carbon fiber (c), a coating film that is formed by moisture curing the moisture curable polyurethane (A) contained in the sizing agent for a carbon fiber; a method for producing a surface-treated carbon fiber (C); a molding material which is characterized by containing a curable resin (D), a polymerizable unsaturated monomer (E) and the carbon fiber (C); and a molded article which is obtained by molding the molding material.

Description

Sizing agent for carbon fiber, carbon fiber, method for producing the same, and molding material and molded article containing carbon fiber

The present invention relates to a carbon fiber sizing agent that can be used in various molding materials including carbon fiber reinforced plastic, a carbon fiber that has been surface-treated using the sizing agent, a method for producing the carbon fiber, and The present invention also relates to a molding material containing the carbon fiber and a molded product obtained by molding the molding material.

As fiber reinforced plastics (FRP), for example, those containing thermosetting resins such as unsaturated polyester resins, vinyl ester resins, epoxy resins, phenol resins and glass fibers as fiber reinforcing materials are generally known. Yes. In particular, FRP consisting of unsaturated polyester resin or vinyl ester resin and glass fiber makes it easy to control viscosity and curing characteristics by using a polymerizable unsaturated monomer such as styrene in combination. Therefore, it is most widely used in FRP.

On the other hand, in the aerospace field, the sports field, and the automobile field, there is a demand for the development of a member that achieves both high strength and light weight. In the FRP, various measures are required to achieve both high strength and light weight. Studies are underway.
For example, a carbon fiber reinforced plastic using carbon fibers instead of conventional glass fibers as a fiber reinforcing material has been studied. Carbon fiber is a fiber with a fine graphite crystal structure that is made by converting polyacrylonitrile resin, organic matter such as pitch from petroleum and coal into fibers, and then undergoing a special heat treatment process. Is light and high in strength.
Therefore, the fiber reinforced plastic obtained by using the carbon fiber and the epoxy resin has remarkably superior strength as compared with the conventional product, and further achieves a weight reduction of about 25% or more of the conventional product. It was a thing.
However, the epoxy resin generally has a high viscosity, and it is difficult to adjust the viscosity by using a polymerizable unsaturated monomer such as the unsaturated polyester or vinyl ester. Since it takes time to cure, there are many restrictions in terms of molding method and molding conditions.
On the other hand, even if the carbon fiber is used in combination with the unsaturated polyester or vinyl ester other than the epoxy resin, sufficient interfacial adhesion cannot be maintained between the unsaturated polyester or the like and the carbon fiber. It was difficult to obtain a carbon fiber reinforced plastic having high strength.

Examples of the FRP containing the vinyl ester, unsaturated polyester and carbon fiber are impregnated with a specific epoxy group-containing vinyl ester resin, a radical polymerizable monomer, a curing agent, and 0.5 to 5% by mass of the vinyl ester resin. A carbon fiber reinforced resin composite material obtained by curing a composition containing carbon fiber is known (see, for example, Patent Document 1).

However, although the carbon fiber reinforced resin composite material has been sufficiently reduced in weight, it may not be practically sufficient in terms of strength.

International Publication WO 2004/067612 Pamphlet

The problem to be solved by the present invention is to provide a sizing agent for carbon fiber that can be applied to various molding methods and can be used for the production of a molded product having both excellent strength and light weight. .
Further, the problem to be solved by the present invention is to provide a carbon fiber subjected to surface treatment using the sizing agent, a method for producing the carbon fiber, and a molding material and a molded product containing the carbon fiber. It is.

As the inventors proceeded to obtain carbon fibers that can be used in combination with curable resins such as vinyl esters and unsaturated polyesters, moisture curable polyurethane was used as a sizing agent for the carbon fibers. It was found that carbon fiber reinforced plastic formed on the surface can form high-strength carbon fiber reinforced plastic when used in combination with a curable resin such as vinyl ester or unsaturated polyester. .

That is, this invention relates to the sizing agent for carbon fiber characterized by containing moisture hardening type polyurethane (A).
Further, the present invention is characterized in that the surface of the carbon fiber (c) has a film formed by the moisture curing reaction of the moisture curable polyurethane (A) contained in the carbon fiber sizing agent. It is related with the carbon fiber (C) to which surface treatment was performed.
In the present invention, the carbon fiber (c) is impregnated with the carbon fiber sizing agent, and when the organic solvent (B) is contained in the carbon fiber sizing agent, the organic solvent (B) is dried. After the removal, the moisture curable polyurethane (A) contained in the sizing agent for carbon fiber was subjected to a moisture curing reaction, whereby the moisture curable polyurethane (A) was moisture cured on the surface of the carbon fiber (c). The present invention relates to a method for producing a surface-treated carbon fiber (C) characterized by forming a film.
Moreover, this invention contains 1 or more types of resin (D) chosen from the group which consists of vinyl ester, vinyl urethane, and unsaturated polyester, a polymerizable unsaturated monomer (E), and the said carbon fiber (C). The present invention relates to a molding material characterized by the above and a molded product obtained by molding the molding material.

If carbon fiber is surface treated using the sizing agent for carbon fiber of the present invention, it can be used in combination with various curable resins such as unsaturated polyester, vinyl ester, and vinyl urethane. Thus, a high-strength molded product that is lighter than that can be obtained. Such molded products can be used in parts such as automobiles and aircraft, industrial members, industrial members, infrastructure members, and medical fields.

It is a 45-times electron micrograph of the fracture surface of the fiber reinforced plastic of Example 3. 2 is an electron micrograph of a fracture surface of the fiber-reinforced plastic of Example 3 at a magnification of 2,000. It is a 45-times electron micrograph of the fracture surface of the fiber reinforced plastic of Comparative Example 6. 4 is an electron micrograph of a fracture surface of a fiber reinforced plastic of Comparative Example 6 at a magnification of 2,000.

The sizing agent for carbon fiber of the present invention forms a film on the surface of carbon fiber used when producing a carbon fiber reinforced plastic, increases the affinity with the curable resin, and improves the strength of the resulting molded product. Can be used for. Moreover, the sizing agent for carbon fibers of the present invention can also be used for bundling carbon fibers.
The sizing agent for carbon fiber of the present invention contains moisture-curable polyurethane (A) and other additives as required.
The sizing agent for carbon fiber of the present invention may be a solventless type that does not contain a solvent such as an organic solvent. However, from the viewpoint of improving the handleability and the efficiency of the surface treatment of carbon fiber, the moisture curable polyurethane ( A) is preferably dissolved or dispersed in the organic solvent (B).
The carbon fiber sizing agent has a mass ratio [(A) / (B)] of the moisture-curable polyurethane (A) and the organic solvent (B) of 0.1 / 99.9 to 5.0 / 95. 0.0 is preferable from the viewpoint of improving the handleability and efficiency of the surface treatment of the carbon fiber, and more preferably 0.1 / 99.9 to 1.0 / 99.0.
The moisture curable polyurethane (A) used in the sizing agent for carbon fiber of the present invention has a functional group that reacts with moisture and moisture in the air to advance a crosslinking reaction. Examples of such a functional group include an isocyanate group and a hydrolyzable silyl group, but vinyl esters and unsaturated polyesters are generally used because a very polar urea bond can be formed and a film having excellent solvent resistance can be formed. It is preferably an isocyanate group because it is difficult to dissolve in a polymerizable unsaturated monomer (E) such as styrene used in combination with the curable resin (D) such as styrene, and can prevent a decrease in strength over time. .

The isocyanate group is preferably present in the range of 5 to 25% by mass with respect to the total amount of the moisture-curable polyurethane (A) in order to prevent the strength from being deteriorated over time.

The moisture curable polyurethane (A) advances the crosslinking reaction of the isocyanate group or the like under the influence of moisture in the atmosphere while adhering to the surface of the carbon fiber (c), and moisture cures on the surface of the carbon fiber (c). A cured film containing the resulting polyurethane is formed. Since such a cured film is difficult to dissolve in a polymerizable unsaturated monomer (E) such as styrene described later, carbon fiber (C) subjected to surface treatment with the cured film and a curable resin (such as vinyl ester) D) is improved in adhesion, and as a result, a carbon fiber reinforced plastic having excellent strength can be obtained.

Here, instead of the moisture-curing polyurethane (A), when a water-based sizing agent in which a high molecular weight thermoplastic urethane resin is emulsified and dispersed in water or a two-component sizing agent containing polyurethane and a curing agent is used. The film formed on the surface of the carbon fiber (c) may dissolve in the polymerizable unsaturated monomer (E) such as styrene, and as a result, a molded article having excellent strength can be obtained. May not be possible.

As said moisture hardening type polyurethane (A), what is obtained by making polyisocyanate (a1) and polyol (a2) react can be used, for example.
Examples of the polyisocyanate (a1) include aromatic polyisocyanates such as 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate. Alternatively, aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, or polyisocyanates having an alicyclic structure can be used. Among these, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate are used from the viewpoint of increasing the crosslink density of the film formed by the sizing agent and forming a film excellent in solvent resistance. It is preferable to use aromatic polyisocyanates such as tolylene diisocyanate and naphthalene diisocyanate.

In addition, as the polyol (a2) that reacts with the polyisocyanate (a1), a polyol having two or more hydroxyl groups is used from the viewpoint of increasing the cross-linking density of the coating film to be formed, and further improving the solvent resistance with high strength. It is preferable to use those having 3 to 6 hydroxyl groups. Further, as the polyol (a2), those having a number average molecular weight of 200 to 5,000 are preferably used, and those having 300 to 2,000 are more preferably used.
As said polyol (a2), polyether polyol, polycarbonate polyol, polyester polyol etc. can be used, for example. Among these, it is preferable to use a polyether polyol, more preferably an aliphatic polyether polyol, in order to obtain a molded article having a high strength.

As the polyether polyol, for example, one obtained by addition polymerization of alkylene oxide to one or more compounds having two or more active hydrogen atoms can be used.

Examples of the compound having two or more active hydrogen atoms include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, and 1,6-hexanediol. Neopentyl glycol, glycerin, trimethylol ethane, trimethylol propane, and the like can be used.

Further, as the alkylene oxide, for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, or the like can be used.

Further, as the polycarbonate polyol, for example, those obtained by reacting a carbonic acid ester and a polyol, or those obtained by reacting phosgene with bisphenol A or the like can be used.

As the carbonate ester, methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate and the like can be used.

Examples of the polyol capable of reacting with the carbonate ester include ethylene glycol, diethylene glycol, 1,2-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5- Relatively low molecular weight dihydroxy compounds such as pentanediol, neopentyl glycol and 1,4-cyclohexanediol, polyethylene glycol, polypropylene glycol, polyester polyols such as polyhexamethylene adipate, and the like can be used.

Examples of the polyester polyol include those obtained by esterifying low molecular weight polyols and polycarboxylic acids, polyesters obtained by ring-opening polymerization reaction of cyclic ester compounds such as ε-caprolactone, and the like. Copolyester of the above can be used.

As the low molecular weight polyol, for example, ethylene glycol, propylene glycol and the like can be used.

As the polycarboxylic acid, for example, succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, and anhydrides or ester-forming derivatives thereof can be used.

The moisture-curable polyurethane (A) can be produced by a known and usual method. For example, it can be produced by a method in which the polyol (a2) from which water has been removed is dropped to the polyisocyanate (a1) in the reaction vessel and then heated until the hydroxyl group of the polyol (a2) is substantially eliminated. it can. The moisture-curable polyurethane (A) can be usually produced without a solvent, but may be produced by reacting in an organic solvent (B) as described later. When reacting in the organic solvent (B), organic compounds such as toluene, xylene, ethyl acetate, methyl ethyl ketone, cellosolve acetate, normal hexane, vinyl group-containing styrene, vinyl toluene, ethyl acrylate, methyl methacrylate, etc. that do not inhibit the reaction. Solvents can be used.

When producing the moisture curable polyurethane (A), a urethanization catalyst can be used as necessary. The urethanization catalyst can be appropriately added at any stage of the reaction.

Examples of the urethanization catalyst include nitrogen-containing compounds such as triethylamine, triethylenediamine and N-methylmorpholine; metal salts such as potassium acetate, zinc stearate and tin octylate; and organometallic compounds such as dibutyltin dilaurate. Can do.

In the reaction of the polyisocyanate (a1) and the polyol (a2), the equivalent ratio of the isocyanate group of the polyisocyanate (a1) to the hydroxyl group of the polyol (a2) [isocyanate group / hydroxyl group] is 1.1 to 10. The reaction is preferably performed in the range of 1.5 to 10, and the reaction is preferably performed in the range of 1.5 to 10.

The moisture curable polyurethane (A) obtained by the above method preferably has a number average molecular weight of 300 to 5,000.

Moreover, it is preferable to use what has a polymerizable unsaturated double bond other than the said isocyanate group as said moisture hardening type polyurethane (A). By using the moisture curable polyurethane (A) having a polymerizable unsaturated double bond, when the curable resin (D) described later is radically polymerized and cured, the moisture curable polyurethane (A) is moisture cured. Since the polymerizable unsaturated double bond derived from the moisture curable polyurethane (A) in the coated film is radically polymerized together, the curable resin (D) and the moisture curable polyurethane (A) are contained. Interfacial adhesion with the carbon fiber (C) surface-treated with the sizing agent for carbon fiber can be further improved.
The polymerizable unsaturated double bond preferably has a double bond titer of 200 to 5,000, preferably 400 to 1,600, based on the total amount of the moisture-curable polyurethane (A). It is more preferable to improve the interfacial adhesion between the curable resin (D) and the carbon fiber (C), which will be described later, and to ensure the solvent resistance of the film made of the sizing agent of the present invention.
The double bond titer is a value obtained by dividing the mass of the moisture curable polyurethane (A) by the number of double bonds present in the moisture curable polyurethane (A) of the mass.
As a method for introducing a polymerizable unsaturated double bond into the moisture-curable polyurethane (A), for example, a polyol (a2) from which water has been removed is added to the polyisocyanate (a1) in the absence of a solvent or an organic solvent. After the dropping, the mixture is heated and reacted until the hydroxyl group of the polyol (a2) substantially disappears to produce a polyurethane having an isocyanate group in the molecule, and then a part of the isocyanate group of the polyurethane and the hydroxyl group And a method of reacting with a compound having a polymerizable unsaturated double bond.
Examples of the hydroxyl group and polymerizable unsaturated double bond-containing compound include hydroxyalkyl (meth) such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 3-hydroxybutyl (meth) acrylate. Acrylates; mono (meth) acrylates of alcohols having two hydroxyl groups such as polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, etc .; di (meth) acrylates of tris (hydroxyethyl) isocyanuric acid, Examples include partial (meth) acrylates of alcohols having three or more hydroxyl groups, such as pentaerythritol tri (meth) acrylate.

The carbon fiber sizing agent of the present invention can be produced, for example, by reacting the polyisocyanate (a1) and the polyol (a2) in the organic solvent (B). When the reaction between the polyisocyanate (a1) and the polyol (a2) is carried out in the absence of a solvent, the resulting moisture-curable polyurethane (A) and the organic solvent (B) are mixed, The carbon fiber sizing agent of the present invention can be obtained by heating or the like as necessary.

The sizing agent for carbon fibers of the present invention may contain other additives as required in addition to the moisture-curable polyurethane (A).
As said additive, surfactant for ensuring the texture according to the use of carbon fiber other than a silane coupling agent, an antifoamer, an antistatic agent, etc. can be used, for example.
The said additive can be mixed with the sizing agent for carbon fibers previously manufactured by the above-mentioned method.

Next, the carbon fiber (c) that can be used in the present invention will be described.
As the carbon fiber (c) used in the present invention, carbon fibers generally known as polyacrylonitrile-based, pitch-based, etc. can be used.
Commercially available products of the polyacrylonitrile-based carbon fiber include, for example, trade names manufactured by Toray Industries, Inc .; “Torayca” series, product names manufactured by Toho Tenax Co., Ltd .; “Tenax” series, manufactured by Mitsubishi Rayon Co., Ltd. Product name; "Pyrofil" series can be used.
Commercially available pitch-based carbon fibers include, for example, trade names manufactured by Mitsubishi Plastics Chemical Co., Ltd .; “DIALEAD” series, trade names manufactured by Kureha Co., Ltd .; “Kureka” series, Osaka Gas Chemical ( “Donna Carbo” series, product name manufactured by Nippon Graphite Fiber Co., Ltd .; “Granock” series can be used.
As the carbon fiber (c), it is preferable to use a polyacrylonitrile-based carbon fiber from the viewpoint of imparting more excellent strength to the molded product.
In addition, as the carbon fiber (c), it is preferable to use one having a fineness from the viewpoint of obtaining a molded product having further excellent strength and the like, and one having a single yarn diameter of 1 μm to 20 μm is used. It is preferable to use one having a thickness of 4 μm or more and 10 μm or less.
The carbon fiber (c) preferably has a strand strength of 3,500 MPa or more, more preferably 4,000 MPa or more.
Moreover, as said carbon fiber (c), it is preferable to use a thing with an elasticity modulus of 220 GPa or more.
The strand strength and the elastic modulus can be measured according to the test method described in JIS R 7608.

The carbon fiber (c) used in the present invention may be, for example, a twisted yarn, a spun yarn, a spun yarn, or a non-woven fabric. Specifically, the filament, yarn, roving, strand, chopped strand, felt, needle punch , Cloth, roving cloth, milled fiber and the like.

Next, the surface of the carbon fiber (c) is surface-treated using the sizing agent for carbon fiber, so that the moisture-curable polyurethane (A) is moisture-cured on the surface of the carbon fiber (c). The carbon fiber (C) in which is formed will be described.
For example, the carbon fiber (C) is impregnated with the carbon fiber sizing agent of the present invention into the carbon fiber (c) which has not been subjected to surface treatment (sizing treatment). In the case of containing B), the moisture-curable polyurethane is removed by drying the carbon fiber (c) adhered and impregnated with B) to remove the organic solvent (B) and then leaving it at room temperature. It can be produced by advancing the moisture curing reaction of (A).
As described above, the surface of the carbon fiber (c) may be impregnated with the carbon fiber sizing agent in the carbon fiber (c), as described above. Moreover, you may apply | coat to the surface of the said carbon fiber (c) using spray application | coating, a brush, etc.
When the carbon fiber sizing agent contains the organic solvent (B), for example, the organic solvent (B) is allowed to stand for a certain period of time in a temperature environment of about room temperature to 150 ° C, preferably 50 ° C to 100 ° C. Can be removed.
In addition, the moisture curing reaction can be allowed to proceed sufficiently, for example, by leaving it for a certain period of time under normal conditions of indoor humidity and room temperature.

The mass of the moisture-cured polyurethane (A) contained in the coating film is moisture-cured in a range of 0.1 to 5.0% by mass with respect to the total mass of the carbon fiber (c). Is preferred.

The surface-treated carbon fiber (C) obtained by the above method is lightened by using it in combination with a curable resin (D) and a polymerizable unsaturated monomer (E) described later. It can be used for the production of strong molded products.

As said curable resin (D), it is suitable to use unsaturated polyester resin, vinyl ester, vinyl urethane, polyester (meth) acrylate etc., for example, unsaturated polyester resin, vinyl ester, and vinyl urethane. More preferably, it is at least one selected from the group consisting of:
As the curable resin (D), when the polymerizable unsaturated monomer (E) is used, a number average molecular weight of 300 or more is adjusted from the viewpoint of adjusting the viscosity so as not to impair the moldability and workability. It is preferable to use what has, and it is more preferable to use the thing of 450 or more.

The unsaturated polyester resin can be obtained, for example, by a condensation reaction of an α, β-unsaturated dibasic acid and a dibasic acid containing a saturated dibasic acid and a polyhydric alcohol, and if necessary, a dicyclopentadiene compound. Things can be used. In the condensation reaction, a polymerization inhibitor or the like may be used together. Examples of the polymerization inhibitor include the same polymerization inhibitors as described later.

Examples of the α, β-unsaturated dibasic acid include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride and the like. The saturated dibasic acids include phthalic acid, phthalic anhydride, halogenated phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, hexahydroterephthalic acid. Acid, hexahydroisophthalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, sebacic acid, 1,12-dodecanedioic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 2,3- Examples thereof include naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid anhydride, 4,4′-biphenyldicarboxylic acid, and dialkyl esters thereof.

Examples of the polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, and 2-methyl. 1,3-propanediol, 1,3-butanediol, neopentyl glycol, hydrogenated bisphenol A, 1,4-butanediol, bisphenol A and propylene oxide or ethylene oxide Adduct, 1,2,3,4-tetrahydroxybutane, glycerin, trimethylolpropane, 1,3-propanediol, 1,2-cyclohexane glycol, 1,3-cyclohexane glycol, 1, 4-cyclohexane glycol, 1,4-cyclohexane dimethanol, para-xylene glycol Bicyclohexyl-4,4' Geo - le, 2,6-decalin glycolate - le, 2,7-decalin glyco - can be used Le like.

Further, as the vinyl ester that can be used for the curable resin (D), for example, epoxy (meth) acrylate is preferably used. As said epoxy (meth) acrylate, what is obtained by making an epoxy resin and unsaturated monobasic acid react in presence of an esterification catalyst can be used. For example, bisphenol type epoxy resin, novolac type epoxy resin, 1,6-naphthalene type epoxy resin di (meth) acrylate, and the like can be mentioned. Of these, those using an epoxy resin having an average epoxy equivalent of 150 to 450 are preferable.

Examples of the bisphenol type epoxy resin include di (meth) acrylate of bisphenol A type epoxy resin, di (meth) acrylate of hydrogenated bisphenol A type epoxy resin, and di (meth) of bisphenol A ethylene oxide addition type epoxy resin. Examples include acrylate, di (meth) acrylate of bisphenol A propylene oxide addition type epoxy resin, di (meth) acrylate of bisphenol F type epoxy resin, di (meth) acrylate of 1,6-naphthalene type epoxy resin, and the like.

As the above-mentioned novolak type epoxy resin, for example, an epoxy resin obtained by a reaction of phenol novolak or cresol novolak with epichlorohydrin or methyl epichlorohydrin can be mentioned.

Further, examples of the unsaturated monobasic acid include acrylic acid, methacrylic acid, cinnamic acid, crotonic acid, sorbic acid, monomethyl malate, monopropyl malate, monobutyl malate, or mono (2-ethylhexyl) malate. Etc.

The reaction between the epoxy resin and the unsaturated monobasic acid is preferably carried out using an esterification catalyst at a temperature in the range of 60 to 140 ° C., particularly preferably in the range of 80 to 120 ° C.
Moreover, you may use a polymerization inhibitor etc. together for reaction of an epoxy resin and unsaturated monobasic acid. Examples of the polymerization inhibitor include the same polymerization inhibitors as described later.

As the esterification catalyst, known and commonly used compounds can be used as they are, but various tertiary amines such as triethylamine, N, N-dimethylbenzylamine, N, N-dimethylaniline or diazabicyclooctane; or Examples thereof include diethylamine hydrochloride.

The number average molecular weight of the epoxy (meth) acrylate is preferably in the range of 450 to 2,500, particularly preferably 500 to 2,200. If the number average molecular weight is 450 to 2,500, the obtained cured product will not be sticky, the strength physical properties will not decrease, the curing time will not be prolonged, and the productivity will not be inferior.

As the vinyl urethane used in the present invention, for example, urethane (meth) acrylate can be used. The urethane (meth) acrylate can be obtained by reacting a polyol, a polyisocyanate, and a hydroxyl group-containing (meth) acrylic compound.

Examples of such polyols include polyether polyols such as polypropylene oxide, polyethylene oxide, polytetramethylene glycol, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, polybutadiene diol, polyisoprene diol, polyester ether polyol, polyester polyol and the like. Is mentioned.

Examples of polyisocyanates include 2,4-tolylene diisocyanate and its isomers or a mixture of isomers (hereinafter abbreviated as TDI), diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane. Examples thereof include diisocyanate, tolidine diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. Of these polyisocyanates, diisocyanates are preferred, and TDI is particularly preferred. These can be used alone or in combination of two or more. Commercially available polyisocyanates include Barnock D-750, Crisbon NX (DIC Corporation product), Death Module L (Sumitomo Bayer Co., Ltd. product), Coronate L (Nippon Polyurethane product), Takenate D102 (Takeda) Yakuhin Kogyo Co., Ltd. product), isonate 143L (manufactured by Mitsubishi Chemical Corporation), and the like.

As the hydroxyl group-containing (meth) acrylic compound, a hydroxyl group-containing (meth) acrylic acid ester is preferable. Examples of the hydroxyl group-containing (meth) acrylic acid ester include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 3-hydroxybutyl (meth) acrylate; polyethylene Mono (meth) acrylates of alcohols having two hydroxyl groups such as glycol mono (meth) acrylate and polypropylene glycol mono (meth) acrylate; adducts of α-olefin epoxide and (meth) acrylic acid, carboxylic acid glycidyl ester And (meth) acrylic acid adducts; a portion of an alcohol having three or more hydroxyl groups such as di (meth) acrylate of tris (hydroxyethyl) isocyanuric acid, pentaerythritol tri (meth) acrylate, etc. ( Data) acrylates and the like.

Further, it is also possible to use those obtained by substituting a part of the hydroxyl group-containing (meth) acrylic compound with a compound such as a hydroxyl group-containing aryl ether or a higher alcohol as long as the effects of the present invention are not impaired.

As a method for producing the urethane (meth) acrylate used in the present invention, a polyether polyol and a polyisocyanate are first reacted in an equivalent ratio [isocyanate group / hydroxyl group] in the range of 1.5 to 2 to contain a terminal isocyanate group. There is a method in which a urethane prepolymer is produced, and then a hydroxyl group-containing (meth) acrylic compound is reacted with the isocyanate group of the prepolymer so that the hydroxyl group is approximately equivalent.

As another method, there may be mentioned a method in which a hydroxyl group-containing (meth) acrylic compound and a polyisocyanate are reacted first, and then the resulting isocyanate group-containing compound and a polyether polyol are reacted.

The molecular weight of the urethane (meth) acrylate used in the present invention is preferably 500 to 30,000 in terms of number average molecular weight, and more preferably 700 to 5,000.

As said polyester (meth) acrylate, the thing obtained by making polyester polyol obtained by making polycarboxylic acid and polyol react, acrylic acid, etc. can be used, for example. Examples of the polycarboxylic acid include phthalic anhydride, terephthalic acid, isophthalic acid, orthophthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, 1,2-hexahydrophthalic acid, 1,3-hexahydrophthalic acid Fumaric acid, maleic acid, itaconic acid and the like can be used. Examples of the polyol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, and 1,3-propanediol. , Diethylene glycol, dipropylene glycol and the like can be used.

Examples of the polymerizable unsaturated monomer (E) used in the present invention include styrene, α-methylstyrene, chlorostyrene, dichlorostyrene, divinylbenzene, t-butylstyrene, vinyltoluene, vinyl acetate, and diaryl. Phthalates, triaryl cyanurates, acrylic esters, methacrylic esters, etc .; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, ( T-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, stearyl (meth) acrylate, (meth) acrylic acid Tridecyl, dicyclopentenyloxyethyl (meth) acrylate , Ethylene glycol monomethyl ether (meth) acrylate, ethylene glycol monoethyl ether (meth) acrylate, ethylene glycol monobutyl ether (meth) acrylate, ethylene glycol monohexyl ether (meth) acrylate, ethylene glycol mono 2-ethylhexyl ether (meth) acrylate , Diethylene glycol monomethyl ether (meth) acrylate, diethylene glycol monoethyl ether (meth) acrylate, diethylene glycol monobutyl ether (meth) acrylate, diethylene glycol monohexyl ether (meth) acrylate, diethylene glycol mono 2-ethylhexyl ether (meth) acrylate, dipropylene glycol monomethyl Ether (meta ) Acrylate, dipropylene glycol monoethyl ether (meth) acrylate, dipropylene glycol monobutyl ether (meth) acrylate, dipropylene glycol monohexyl ether (meth) acrylate, dipropylene glycol mono 2-ethylhexyl ether (meth) acrylate, diethylene glycol di (Meth) acrylate, dipropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, PTMG dimethacrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol di ( (Meth) acrylate, 2-hydroxy 1,3-dimethacryloxypropane, 2,2-bis [4- (methacryloxyethoxy) phenyl] propane, 2,2-bis [ -(Methacryloxy / diethoxy) phenyl] propane, 2,2-bis [4- (methacryloxy / polyethoxy) phenyl] propane, tetraethylene glycol diacrylate, bisphenol AEO modified (n = 2) diacrylate, isocyanuric acid EO modified (n = 3) Diacrylate, pentaerythritol diacrylate monostearate and the like.
Among these, the polymerizable unsaturated monomer (E) of the present invention is preferably at least one selected from the group consisting of styrene and 2-hydroxyethyl (meth) acrylate.

The molding material of the present invention contains the curable resin (D), the polymerizable unsaturated monomer (E), and the carbon fiber (C).
As the molding material of the present invention, for example, a prepreg or a sheet molding compound (SMC) can be used. The molding material can be produced, for example, by impregnating the carbon fiber (C) with a resin composition containing the curable resin (D) and the polymerizable unsaturated monomer (E). it can.
If necessary, the molding material can be used in combination with a radical polymerization initiator, a radical polymerization accelerator or the like.

As the radical polymerization initiator, for example, a thermosetting agent or a photocuring agent can be used.
Examples of the thermosetting agent include diacyl peroxide-based, peroxyester-based, hydroperoxide-based, dialkyl peroxide-based, ketone peroxide-based, peroxyketal-based, alkylperester-based, and percarbonate-based organic peroxides. Oxides can be used.
The amount of the thermosetting agent used is not particularly limited as long as the object of the present invention can be achieved, but is 0.5 to 5 with respect to 100 parts by mass of the curable resin (D). It is preferable to use parts by mass.
As the photocuring agent, for example, benzoin alkyl ether, benzophenone, benzyl, methyl orthobenzoyl benzoate, benzyl dimethyl ketal, 2,2-diethoxyacetophenone, 2-hydroxy-2-methylpropiophenone, etc. can be used. .

Examples of the radical polymerization accelerator include metal soaps such as cobalt naphthenate, cobalt octylate, zinc octylate, vanadium octylate, copper naphthenate, and barium naphthenate; vanadium acetyl acetate, cobalt acetyl acetate, iron acetylacetate Metal chelates such as nate; aniline, N, N-dimethylaniline, N, N-diethylaniline, p-toluidine, N, N-dimethyl-p-toluidine, N, N-bis (2-hydroxyethyl) -p -Toluidine, 4- (N, N-dimethylamino) benzaldehyde, 4- [N, N-bis (2-hydroxyethyl) amino] benzaldehyde, 4- (N-methyl-N-hydroxyethylamino) benzaldehyde, N, N-bis (2-hydroxypropyl) -p-toluigi N, N-substituted anilines such as N-ethyl-m-toluidine, triethanolamine, m-toluidine, diethylenetriamine, pyridine, phenylmorpholine, piperidine, N, N-bis (hydroxyethyl) aniline, diethanolaniline; , N-substituted-p-toluidine, 4- (N, N-substituted amino) benzaldehyde and other amines can be used, and the amines and metal soap systems are preferably used.
The radical polymerization accelerator may be mixed in advance with the curable resin (D) or the like, but the carbon fiber (C), the curable resin (D), the polymerizable unsaturated monomer ( You may use together, when mixing E).
The radical polymerization accelerator is preferably used in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the curable resin (D).

In the molding material of the present invention, a polymerization inhibitor or the like can be used to adjust the curing rate.
Examples of the polymerization inhibitor include trihydrobenzene, toluhydroquinone, 1,4-naphthoquinone, parabenzoquinone, hydroquinone, benzoquinone, hydroquinone monomethyl ether, p-tert-butylcatechol, catechol, 2,6-di-tert-butyl- 4-methylphenol and the like can be mentioned. The addition amount of the polymerization inhibitor is preferably 10 to 1000 ppm, more preferably 50 to 200 ppm, based on the resin used in the present invention.

The molding material of the present invention includes, for example, a hand lay-up method, a spray-up method, an FRP lining method, a resin transfer molding method (RTM method), a resin injection method (RI method), a vacuum assist resin transfer molding method (VARTM method), A molded article having high hardness can be obtained by molding by various molding methods such as an infusion molding method, a press molding method, an autoclave molding method, a filament winding method, and a pultrusion molding method.
The molding material of this invention can adjust the viscosity of a molding material easily, without impairing sclerosis | hardenability etc. by using the said polymerizable unsaturated monomer (E). Therefore, with the molding material of the present invention, a desired molded product can be easily produced by a molding method such as an infusion molding method that can be applied when the molding material has a relatively low viscosity.
By adopting such an infusion molding method, it is possible to increase the volume content of carbon fibers in the obtained molded product and to obtain a molded product with even better strength.
Curing of the molding material proceeds by radical polymerization by heating or light irradiation, for example, under pressure or normal pressure.
The radical polymerization proceeds between the polymerizable unsaturated double bond of the curable resin (D) and the polymerizable unsaturated double bond of the polymerizable unsaturated monomer (E). When a polymerizable unsaturated double bond-containing moisture-curable polyurethane is used as the sizing agent of the invention, the polymerizable unsaturated double bond of the polyurethane also contributes to the radical polymerization reaction. Thereby, the interface adhesive force of curable resin (D) and carbon fiber (C) improves, and it becomes possible to obtain a highly strong molded article.

The molded article of the present invention obtained by the above method is, for example, a blade for wind power generation, an automobile outer plate, a vehicle platform member, a boat, a water bike, a railway vehicle member, a pipe, an aircraft member, a building member for seismic reinforcement, an industry It can be used for industrial robots.

[Example 1] <Preparation of carbon fiber sizing agent (S-1)>
282 parts by mass of Millionate MR-200 (manufactured by Nippon Polyurethane Industry Co., Ltd .: Crude MDI (crude diphenylmethane diisocyanate)) in a 2-liter four-necked flask equipped with a thermometer, stirrer, inert gas inlet, and reflux condenser , 91 parts by mass of propylene oxide adduct of glycerin (Sanix GP-400 manufactured by Sanyo Chemical Industries Co., Ltd.), 300 parts by mass of dried xylene and 350 parts by mass of dried ethyl acetate are charged and reacted at 50 to 70 ° C. Thus, an organic solvent solution of moisture curable polyurethane was obtained (appearance: brown liquid, free NCO%: 5.9%, viscosity: 30 CPS (20 ° C.), nonvolatile content: 36% by mass).
Next, 10 parts by mass of the moisture-curable polyurethane organic solvent solution and 990 parts by mass of dried acetone were mixed to obtain a sizing agent for carbon fiber (S-1) having a nonvolatile content of 0.36% by mass.

<Production of carbon fiber cloth not subjected to sizing treatment>
Pyrofil TR3110M (Mitsubishi Rayon Co., Ltd., 200 g / m ² , single yarn diameter 7 μm, strand strength 4,400 MPa, elastic modulus 235 GPa, polyacrylonitrile carbon fiber cloth subjected to sizing treatment (surface treatment)) at room temperature A test piece having a size of about 300 mm × 300 mm obtained by cutting was dipped in acetone having a mass of about 30 times the mass part of the test piece and left for 12 hours.
After the immersion, the test piece is dried for 2 hours using a dryer at 60 ° C. to remove the resin and the like attached to the surface of the carbon fiber, and carbon in a state where sizing treatment (surface treatment) is not performed. A test piece made of fiber cloth was obtained.

<Production of carbon fiber cloth that has been sized by the sizing agent of the present invention>
The test piece not subjected to sizing treatment prepared by the above method was sufficiently immersed in the sizing agent for carbon fiber (S-1) obtained in Example 1, and then dried in a dryer adjusted to 60 ° C. for 2 hours. By proceeding with moisture curing, carbon fiber cloth (CF-1) subjected to sizing treatment was produced. At this time, the mass of the moisture-cured polyurethane contained in the coating formed on the surface of the test piece by the carbon fiber sizing agent (S-1) was 0.34% by mass with respect to the total mass of the test piece. there were.

[Example 2] <Preparation of carbon fiber sizing agent (S-2)>
352 parts by mass of Millionate MR-200 (manufactured by Nippon Polyurethane Industry Co., Ltd .: Crude MDI) in a 2 liter four-necked flask equipped with a thermometer, stirrer, inert gas inlet, and reflux condenser, propylene oxide of glycerin 122 parts by weight of an adduct (Exenol # 430 manufactured by Asahi Glass Co., Ltd.) and 197 parts by weight of dried xylene were charged and reacted at 50 to 70 ° C. to obtain a first stage reaction solution.
Subsequently, 197 parts by weight of dried xylene, 602 parts by weight of dried ethyl acetate, 49 parts by weight of 2-hydroxyethyl methacrylate, Millionate MR-200 (manufactured by Nippon Polyurethane Co., Ltd .: Crude) MDI) 81 parts by weight were charged and reacted at 50 to 70 ° C. to obtain an organic solvent solution of moisture-curable polyurethane (appearance: brown liquid, free NCO%: 5.7, viscosity: 35 CPS (20 ° C.), Nonvolatile content: 38% by mass).
Next, 9.5 parts by mass of the moisture-curable polyurethane organic solvent solution and 990 parts by mass of dried acetone are mixed to obtain a carbon fiber sizing agent (S-2) having a nonvolatile content of 0.36% by mass. It was.
Further, carbon fiber subjected to sizing treatment by the same method as described above except that the sizing agent for carbon fiber (S-2) is used instead of the sizing agent for carbon fiber (S-1). A cloth (CF-2) was produced.

[Comparative Example 1] <Preparation of carbon fiber sizing agent (S-3)>
100 parts by mass of a polyester polyol obtained by reacting neopentyl glycol, 1,6-hexanediol and adipic acid in a nitrogen-substituted container equipped with a thermometer, a nitrogen gas introduction tube, and a stirrer; 2-Methylolpropionic acid 13 parts by mass, 1,4-cyclohexanedimethanol 21 parts by mass, dicyclohexylmethane diisocyanate 43 parts by mass, isophorone diisocyanate 36 parts by mass in a mixed solvent of methyl ethyl ketone 59 parts by mass and methylpyrrolidone 119 parts by mass To obtain an organic solvent solution of a urethane prepolymer having an isocyanate group at the molecular end.
Next, 10 parts by mass of triethylamine is added to the organic solvent solution of the urethane prepolymer to neutralize part or all of the carboxyl groups of the urethane prepolymer, and 300 parts by mass of water is further added and sufficiently stirred. As a result, an aqueous dispersion of urethane resin was obtained.
Next, 8 parts by mass of a 25% by mass ethylenediamine aqueous solution is added to the aqueous dispersion, and the resulting urethane resin is chain-extended by stirring, followed by aging and desolvation, thereby having a non-volatile content of 35% by mass. A urethane resin composition was obtained.
Next, 10 parts by mass of the urethane resin composition and 90 parts by mass of water were mixed to obtain a carbon fiber sizing agent (S-3) having a nonvolatile content of 0.35% by mass.
Further, carbon fiber subjected to sizing treatment by the same method as described above except that the sizing agent for carbon fiber (S-3) is used instead of the sizing agent for carbon fiber (S-1). A cloth (CF-3) was produced.

[Comparative Example 2] <Preparation of carbon fiber sizing agent (S-4)>
Takenate D-140N (manufactured by Mitsui Takeda Chemical Co., Ltd., trimethylolpropane adduct of isophorone diisocyanate) in a nitrogen purged vessel equipped with a thermometer, nitrogen gas inlet tube, stirrer, dropping funnel, and cooling tube : Ethyl acetate solution having a non-volatile content of 75% by mass) 616 parts by mass and 39 parts by mass of 3-methoxy-n-butyl acetate were mixed, and then 145 parts by mass of methyl ethyl ketoxime was added dropwise to the mixture. A blocked isocyanate compound in which all isocyanate groups are blocked with methyl ethyl ketoxime by reacting for a period of time (nonvolatile content: 75% by mass; when the methyl ethyl ketoxime is dissociated to form an isocyanate group, the effective isocyanate group content is 8. 3% by mass) was obtained.
Next, 113 parts by mass of the blocked isocyanate compound, 75 parts by mass of a polyester polyol (manufactured by DIC Corporation, Vernock D-161) and 0.8 part by mass of dibutyltin diacetate as a dissociation catalyst were mixed, and nonionic surface activity was further obtained. By adding 8 parts by mass of polyoxyethylene polyoxypropylene glycol (Pluronic F-108 manufactured by Adeka Co., Ltd.) as an agent and adding 132 parts by mass of ion-exchanged water gradually while mixing vigorously with a homogenizer, the mixture is non-volatile. A polyurethane emulsion having a content of 50% by weight was obtained.
Next, 70 parts by mass of the urethane emulsion and 930 parts by mass of water were mixed to obtain a carbon fiber sizing agent (S-4) having a nonvolatile content of 0.35% by mass.
Further, carbon fiber subjected to sizing treatment by the same method as described above except that the sizing agent for carbon fiber (S-4) is used instead of the sizing agent for carbon fiber (S-1). A cloth (CF-4) was produced.

[Preparation of resin composition]
[Preparation Example 1] <Preparation of vinyl ester resin (VE-1)>
Into a 5 L four-necked flask equipped with a thermometer, a stirrer, and a reflux condenser, Epicron 850 (DIC phenol bisphenol A epoxy resin, epoxy equivalent: 187) 1460 parts by mass, methacrylic acid 644 parts by mass Parts, hydroquinone 0.47 parts by mass and triethylamine 3.5 parts by mass were charged to 100 ± 10 ° C. and reacted at the same temperature for 8 hours to obtain epoxy methacrylate having a number average molecular weight of 550. Thereafter, 1133 parts by mass of styrene monomer and 0.18 parts by mass of hydroquinone were further added and mixed to obtain a vinyl ester resin solution (VE-1) having a nonvolatile content of 65.0% by mass and an acid value of 4.6.

[Preparation Example 2] <Preparation of unsaturated polyester resin (UP-1)>
A 2 L 4-neck flask equipped with a thermometer, stirrer, and reflux condenser was charged with 350 parts by weight of propylene glycol and 382 parts by weight of isophthalic acid, heated to 200 ° C., and subsequently solid acid value at 210 ± 10 ° C. The reaction was continued until 2 or less.
Next, 221 parts by mass of propylene glycol, 534 parts by mass of fumaric acid, and 0.1 parts by mass of hydroquinone were charged into the reaction mixture, and the temperature was raised to 210 ° C. and reacted at the same temperature until the solid acid value reached 18. An unsaturated polyester resin having a number average molecular weight of 2,500 was obtained.
After completion of the reaction, the mixture was cooled to 180 ° C., and further charged with 800 parts by mass of a styrene monomer in which 0.12 parts by mass of catechol was previously dissolved, and then cooled to 25 ° C., thereby unsaturated polyester resin (UP -1) was obtained.

[Example 3] <Production of carbon fiber reinforced plastic>
A mixture of 100 parts by mass of the vinyl ester resin solution (VE-1) and 0.5 parts by mass of 6% by mass cobalt naphthenate and 1.0 part by mass of Permec N (methyl ethyl ketone peroxide manufactured by NOF Corporation). Was laminated on the sizing-treated carbon fiber cloth obtained in Example 1 on a 350 mm × 350 mm glass plate subjected to a release treatment by a hand lay-up molding method (8 ply). After curing at room temperature (25 ° C.) for 12 hours and further curing at 60 ° C. for 3 hours, a carbon fiber reinforced plastic (carbon fiber content: 50% by volume) was obtained.

[Examples 4 to 6, Comparative Examples 3 to 7]
A carbon fiber reinforced plastic was obtained in the same manner as in Example 3 except that the carbon fiber cloth or glass fiber cloth and resin composition described in Tables 1 to 3 below were used.

[Comparative Example 8]
A mixture of 90 parts by mass of Epicron 850 (epoxy resin manufactured by DIC Corporation) and 10 parts by mass of TETA (triethyltetramon manufactured by Tosoh Corporation) on a 350 mm × 350 mm glass plate subjected to release treatment. Laminated by hand lay-up molding method (8 ply) on carbon fiber cloth that has been sized by “Pyrofil TR3110M” manufactured by Mitsubishi Rayon Co., Ltd., and cured at room temperature (25 ° C.) for 12 hours. Then, the mixture was further cured at 60 ° C. for 3 hours to obtain a carbon fiber reinforced plastic (carbon fiber content: 50% by volume).

[Strength Evaluation Method 1]
The strength of the carbon fiber reinforced plastic and glass fiber reinforced plastic obtained above was evaluated by bending strength described later and visual observation of the cross section of the fiber reinforced plastic.
[Bending strength]
The evaluation was based on the measurement result of “bending strength” performed according to JIS K 7074 “Bending test method of carbon fiber reinforced plastic”.

[Strength Evaluation Method 2]
<Observation of fracture surface of carbon fiber reinforced plastic>
The fracture surface of the fiber reinforced plastic formed by the bending test was observed at 45 times and 2,000 times using an electron microscope (JSM-5900LV, manufactured by JEOL Ltd.). Evaluated as “good” when the fractured carbon fiber and curable resin are broken together, and the fiber is exposed from the fractured surface in a sagittal manner, breaking at the interface between the fiber and the curable resin It was evaluated as “bad”. The fracture surface of the carbon fiber reinforced plastic of Example 3 is shown in FIGS. 1 and 2, and the fracture surface of the carbon fiber reinforced plastic of Comparative Example 6 is shown in FIGS.

Explanation of abbreviations in the table: “WF350”: Nittobo Co., Ltd. surface-treated glass fiber cloth (350 g / m ² )
"Pyrofil TR3110M": polyacrylonitrile-based carbon fiber cloth for epoxy resin (200 g / m ² ) subjected to surface treatment manufactured by Mitsubishi Rayon Co., Ltd.- "Pyrofil TR3110MS": surface manufactured by Mitsubishi Rayon Co., Ltd. Treated polyacrylonitrile-based carbon fiber cloth (200 g / m ² ) for vinyl ester resin

[Method for evaluating moldability]
<Production of molded product by infusion molding method>
Chemlyse PMR (silicon mold release agent manufactured by CHEMREASE) was applied to the surface of a 100 cm × 100 cm glass plate to perform a mold release treatment.
Next, the same carbon fiber cloth as used in Example 3 was cut into a size of 500 mm × 700 mm, and 8 plies were placed in the center of the glass plate. Next, BLEEDER LEASE B (peel ply manufactured by AIRTECH) cut to 600 mm × 900 mm was aligned on the previous carbon fiber cloth and placed in the center of the glass plate.
Next, a polyethylene spiral tube (SE-13 inner diameter 10 mm manufactured by Morimiya Electric Co., Ltd.) having the same length as the peel ply short side was placed under both ends of the peel ply on the short side. A polyethylene tube having an outer diameter of 10 mm was connected to one end of each spiral tube to form a resin injection line and a vacuum degassing line, respectively. Next, the entire surface of the glass was covered with a bagging film (IPPLON DP-1000 nylon 25 μm thickness manufactured by AIRTECH), and the peripheral edge of the glass was bonded to the bagging film with a sealant tape (A800-G3 manufactured by AIRTECH). At that time, the gap between the resin injection line, the vacuum degassing line, the peripheral edge of the glass and the bagging film was also filled with a sealant tape to ensure the airtightness between the film and the glass plate.
Next, a polyethylene pump hose used as a vacuum degassing line is connected to a vacuum pump via a resin trap equipped with a vacuum gauge. On the other hand, a polyethylene hose used as a resin injection line is closed at the middle with a clamp. It installed in the bottom face of the resin compounding tank.
Next, the vacuum pump was operated, and vacuum deaeration and airtightness were ensured in order to maintain the degree of vacuum in the path and between the bagging film glass plates at -700 to -760 mmHg.
Next, 100 parts by mass of the vinyl ester resin solution (VE-1) was mixed with 0.5 parts by mass of 6% by mass cobalt naphthenate and 1.0 part by mass of Permec N (methyl ethyl ketone peroxide manufactured by NOF Corporation). The mixture (Z-1) thus prepared was charged into a resin compounding tank, the clamp was released, and resin injection was started. After confirming that the resin reached the entire surface of the carbon fiber cloth, the resin injection line was clamped again. The injection time at this time was 15 minutes. After the injection, the molded product (R-1) was obtained by sufficiently curing at room temperature.
On the other hand, instead of the mixture (Z-1), a mixture (Z-) containing 90 parts by mass of Epiclone 850 (epoxy resin manufactured by DIC Corporation) and 10 parts by mass of TETA (triethyltetramine manufactured by Tosoh Corporation). 2; using the same composition as that used in Comparative Example 8 and using the commercially available Pyrofil TR3110M as the carbon fiber cloth, the molded product (R- 2) was obtained.
The molded product (R-1) was such that the mixture (Z-1) was spread over the entire surface of the carbon fiber cloth without causing defects such as residual bubbles after an injection time of 15 minutes. On the other hand, in the molded product (R-2), the mixture (Z-2) which is the molding material used has a high viscosity, and it is difficult to adjust the viscosity using a polymerizable unsaturated monomer. For this reason, even if the injection time is 30 minutes, the resin does not reach the entire surface of the carbon fiber cloth, resulting in a molded product including air bubbles as a whole, and does not have a practically sufficient strength.

Claims

A carbon fiber sizing agent characterized by containing a moisture-curing polyurethane (A).
The carbon fiber sizing agent according to claim 1, wherein the moisture-curable polyurethane (A) has an isocyanate group in the molecule.
The moisture curable polyurethane (A) is obtained by reacting a polyisocyanate (a1) and a polyol (a2), the polyisocyanate (a1) contains an aromatic polyisocyanate, and the polyol (a2) The sizing agent for carbon fibers according to claim 1, comprising an aliphatic polyether polyol.
The sizing agent for carbon fiber according to any one of claims 1 to 3, wherein the moisture-curable urethane (A) has an isocyanate group and a polymerizable unsaturated double bond in the molecule.
The carbon fiber sizing agent according to any one of claims 1 to 4, further comprising an organic solvent (B).
The mass ratio [(A) / (B)] of the moisture-curable polyurethane (A) and the organic solvent (B) is 0.1 / 99.9 to 5.0 / 95.0. The sizing agent for carbon fibers described in 1.
A coating formed on the surface of the carbon fiber (c) by the moisture curing reaction of the moisture curable polyurethane (A) contained in the sizing agent for carbon fiber according to any one of claims 1 to 6. A carbon fiber (C) subjected to a surface treatment.
When the carbon fiber (c) is impregnated with the carbon fiber sizing agent according to any one of claims 1 to 6, and the organic solvent (B) is contained in the carbon fiber sizing agent, the organic solvent (B ) Is removed by drying, and then the moisture curable polyurethane (A) contained in the sizing agent for carbon fiber is subjected to a moisture curing reaction on the surface of the carbon fiber (c). A method for producing a surface-treated carbon fiber (C), wherein the film is moisture-cured.
The mass of the moisture-cured polyurethane (A) contained in the film is moisture-curing polyurethane is in the range of 0.1 to 5.0% by mass with respect to the total mass of the carbon fiber (c). The manufacturing method according to claim 8.
A molding material comprising a curable resin (D), a polymerizable unsaturated monomer (E), and the carbon fiber (C) according to claim 7.
The molding material according to claim 10, wherein the curable resin (D) is at least one selected from the group consisting of vinyl esters, vinyl urethanes and unsaturated polyester resins.
The molding material according to claim 10, wherein the polymerizable unsaturated monomer (E) is at least one selected from the group consisting of styrene and 2-hydroxyethyl (meth) acrylate.
The molding according to claim 10, wherein a mass ratio [(D) / (E)] of the curable resin (D) and the polymerizable unsaturated monomer (E) is 20/80 to 80/20. material.
A molded product obtained by molding the molding material according to any one of claims 10 to 13.