Sizing agent for fibers and application thereof

Abstract

Provided is a sizing agent for fibers, which is capable of suppressing hardening of fiber bundles over time. A sizing agent for fibers, which contains an epoxy resin (A) and a surfactant (B), and wherein the complex viscosity of the non-volatile matter of the sizing agent at 25 DEG C, a strain of 0.005, and a frequency of 1 Hz is 1 * 102 to 1 * 104 Pa.s, and the loss modulus of the non-volatile matter of the sizing agent at 120 DEG C, a strain of 1, and a frequency of 1 Hz is 1 to 15 Pa. In the sizing agent for fibers in the technical scheme 1 requested to be protected preferably, the epoxy resin (A) contains a compound (a1) shown in the following general formula (1).

Description

Technical Field

[0001] The present invention relates to a fiber sizing agent and its use, and more particularly to a fiber sizing agent, a fiber strand using the fiber sizing agent, and a fiber-reinforced composite material. Background Art

[0002] Fiber-reinforced composite materials that are reinforced with various synthetic fibers to form plastic materials (also called matrix resins) are widely used in automotive, aviation and aerospace applications, sports and leisure applications, and general industrial applications. Fibers used in these composite materials include various inorganic fibers such as carbon fibers, glass fibers, and ceramic fibers, and various organic fibers such as aramid fibers, polyamide fibers, and polyethylene fibers. These various fibers are usually manufactured in the form of filaments and then used after various high-order processing steps. The high-order processing step refers to processing into a sheet-like intermediate material called a unidirectional prepreg by a hot melt method, a drum winding method, etc., or processing by a filament winding method, or processing into a woven fabric or a short fiber (chopped fiber) shape as appropriate.

[0003] Epoxy resin is widely used as the matrix resin of fiber reinforced composite materials. In addition to epoxy resin, unsaturated polyester resin, vinyl ester resin, acrylic resin, etc. are also used as the matrix resin of free radical polymerization system.

[0004] In order to improve the mechanical strength of fiber-reinforced composite materials, the wettability and adhesion between the matrix resin and the fibers are very important, and sizing agents that can improve the wettability and adhesion between the fibers and the epoxy resin and free radical polymerization matrix resins have been proposed.

[0005] In various high-order processing steps, various fibers require bundling properties to prevent the degradation of various physical properties and quality caused by breakage and fuzzing. In addition, in order to produce high-quality composites, fiber opening properties that can expand the width of the strands uniformly without gaps while maintaining the shape are required.

[0006] The sizing agents described in Patent Document 1 or Patent Document 2 can improve the bundling property by suppressing the reduction of various physical properties and quality due to fiber breakage and fuzzing. However, fiber bundles to which these sizing agents are attached do not cause any problems immediately after the sizing agents are applied, but when fiber bundles stored for a certain period of time are used, the fiber opening property is reduced, and a high-quality composite cannot be obtained.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2015-190067

[0010] Patent Document 2: Japanese Patent Application Publication No. 2016-89276 Summary of the invention

[0011] Problems to be solved by the invention

[0012] The present inventors investigated the cause of this problem and found that the fiber bundle to which the sizing agent adhered hardened over time, thereby reducing the fiber openability.

[0013] An object of the present invention is to provide a fiber sizing agent capable of suppressing the time-dependent hardening of a fiber bundle to which the sizing agent is attached, and a fiber strand and a fiber-reinforced composite material using the fiber sizing agent.

[0014] Means to solve the problem

[0015] The present inventors have conducted intensive studies to solve the above problems and have found that a fiber sizing agent containing an epoxy resin (A) and a surfactant and having a complex viscosity and a loss modulus of specific values ​​can solve the above problems.

[0016] That is, the sizing agent for fibers of the present invention includes the following aspects.

[0017] <1> A fiber sizing agent comprising an epoxy resin (A) and a surfactant (B), wherein the complex viscosity of the non-volatile matter of the sizing agent at 25°C, a strain of 0.005, and a frequency of 1 Hz is 1×10 2 Up to 1×10 4 Pa·s, and the loss modulus of the non-volatile matter of the sizing agent at 120° C., strain 1, and frequency 1 Hz is 1 to 15 Pa.

[0018] <2> like <1> In the fiber sizing agent, the epoxy resin (A) contains a compound (a1) represented by the following general formula (1).

[0019] (1)

[0020] (In formula (1), R 1 , R 2 , R 3 and R 4 Each independently represents a hydrogen atom or a methyl group. n is an integer greater than 0.

[0021] <3> like <2> In the fiber sizing agent, the weight ratio of the epoxy resin (A) in the non-volatile matter of the sizing agent is 20 weight % or more, and the compound (a1) contains a compound wherein n is 2 or more.

[0022] <4> like <2> to <3> The fiber sizing agent according to any one of the preceding claims, wherein the compound (a1) contains the R 1 , R 2 , R3 and R 4 A compound containing hydrogen atoms.

[0023] <5> like <1> to <4> The fiber sizing agent described in any one of the preceding claims, wherein the total content of the vinyl ester resin, the saturated polyester resin, the unsaturated polyester resin and the rosin ester resin in the non-volatile matter of the sizing agent is 20 wt % or less.

[0024] <6> A fiber thread material having <1> to <5> The fiber sizing agent according to any one of the above.

[0025] <7> A fiber-reinforced composite material comprising a matrix resin and <6> The fiber line material.

[0026] <8> like <7> In the fiber-reinforced composite material, the matrix resin is a thermosetting resin.

[0027] Effects of the Invention

[0028] The fiber sizing agent of the present invention can suppress the hardening of the fiber bundle over time. By using the reinforcing fiber strand of the present invention, a reinforced fiber composite material having excellent physical properties can be obtained. DETAILED DESCRIPTION

[0029] Each component of the fiber sizing agent of the present invention is described in detail.

[0030] [Epoxy resin (A)]

[0031] The epoxy resin (A) is a component of the fiber sizing agent of the present invention.

[0032] Examples of the epoxy resin include bisphenol epoxy resins, bisphenol novolac epoxy resins, amine epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, resorcinol epoxy resins, phenol aralkyl epoxy resins, naphthol aralkyl epoxy resins, dicyclopentadiene epoxy resins, epoxy resins having a biphenyl skeleton, isocyanate-modified epoxy resins, tetraphenylethane epoxy resins, triphenylmethane epoxy resins, and the like.

[0033] Here, the bisphenol epoxy resin refers to a substance in which two phenolic hydroxyl groups of a bisphenol compound are glycidylated, and examples thereof include bisphenol A type, bisphenol F type, bisphenol AD ​​type, bisphenol S type, or halogenated products, alkyl substituted products, acid-modified products, hydrides of these bisphenols, etc. In addition, it is not limited to monomers, and high molecular weight products having multiple repeating units can also be used.

[0034] Examples of the amine type epoxy resin include tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, triglycidylaminocresol, tetraglycidylxylenediamine, and halides, alkynol-substituted products, and hydrides thereof.

[0035] From the viewpoint of inhibiting time-dependent curing, the epoxy equivalent of the epoxy resin (A) is preferably 100 to 2500 g / eq. The upper limit of the epoxy equivalent is more preferably 2000 g / eq, and more preferably 1600 g / eq. On the other hand, the lower limit of the epoxy equivalent is more preferably 200 g / eq, and more preferably 300 g / eq. In addition, the epoxy equivalent is a value obtained according to JIS-K-7236. In addition, for example, it is more preferably 200 to 2000 g / eq, and more preferably 300 to 1600 g / eq.

[0036] From the viewpoint of heat resistance and the range that easily satisfies the complex viscosity and loss modulus of the present invention described later, the weight average molecular weight of the epoxy resin (A) is preferably 100 to 10000. The upper limit of the average molecular weight is more preferably 8000, and further preferably 6000. On the other hand, the lower limit of the average molecular weight is more preferably 400, and further preferably 600. In addition, for example, it is more preferably 400 to 8000, and further preferably 600 to 6000.

[0037] From the viewpoint of improving the adhesion between the reinforcing fiber and the matrix resin, the epoxy resin is preferably an aromatic epoxy resin having an aromatic ring in its molecular structure.

[0038] The above-mentioned aromatic epoxy resins can include polyglycidyl ether compounds of mononuclear polyphenol compounds such as hydroquinone, resorcinol, and catechol; polyglycidyl ether compounds of polynuclear polyphenol compounds such as dihydroxynaphthalene, biphenol, bisphenol F, bisphenol A, phenol phenolic acid, o-cresol phenolic acid, resorcinol phenolic acid, bisphenol F phenolic acid, bisphenol A phenolic acid, dicyclopentadiene-modified phenol, triphenylmethane, and tetraphenylethane; etc.

[0039] Among these aromatic epoxy resins, it is more preferable to contain the compound (a1) represented by the following general formula (1) from the viewpoint of the effect of the present application.

[0040] (1)

[0041] (In formula (1), R 1 , R 2 , R 3 and R 4 Each independently represents a hydrogen atom or a methyl group. n is an integer greater than 0.

[0042] In addition, in the compound (a1), it is preferred to contain R 1 , R 2 , R 3 and R 4 The bisphenol F epoxy resin containing R 1 , R 2 , R 3 and R 4 The bisphenol A type epoxy resin having each of methyl groups preferably contains at least one selected from bisphenol F type epoxy resin and bisphenol A type epoxy resin from the viewpoint of suppressing curing over time.

[0043] From the viewpoint of suppressing the change over time and easily satisfying the ranges of the complex viscosity and loss modulus of the present invention described later, the compound (a1) preferably contains a compound in which n is 2 or more, and more preferably contains a compound in which n is 3 or more in the general formula (1).

[0044] The method for producing the epoxy resin is not particularly limited, and a known method can be used. In addition, the epoxy resin is generally a commercially available product, and these commercially available epoxy resins can be used in the fiber sizing agent of the present invention.

[0045] [Surfactant (B)]

[0046] The surfactant (B) is used together with the epoxy resin (A) to facilitate dispersion of the epoxy resin (A) in water, thereby improving the handleability and long-term stability of the fiber sizing agent.

[0047] The surfactant (B) is not particularly limited, and a known surfactant can be appropriately selected from nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. The surfactant (B) preferably contains at least one selected from nonionic surfactants and anionic surfactants, and more preferably contains a nonionic surfactant. The surfactant can be used alone or in combination of two or more.

[0048] Nonionic surfactants are organic compounds having a hydrophilic group and a hydrophobic group. Examples of the hydrophilic group include polyoxyethylene and polyoxyethylene / polyoxypropylene random copolymer groups. Examples of the hydrophobic group include alkyl, alkenyl, aryl, alkylaryl, polycyclic aromatic, and polyoxypropylene groups.

[0049] Examples of nonionic surfactants include oxyalkylene-added nonionic surfactants (substances obtained by adding oxyalkylene oxides such as ethylene oxide and propylene oxide to higher alcohols, higher fatty acids, alkylphenols, styrenated phenols, benzylphenols, bisphenols, sorbitan, sorbitan esters, castor oil, hydrogenated castor oil, etc. (two or more kinds may be used in combination)), substances obtained by adding higher fatty acids to polyalkylene glycols, ethylene oxide / propylene oxide copolymers, etc. Among nonionic surfactants, nonionic surfactants having polyoxyethylene groups at multiple terminals are preferred from the viewpoint of exerting the effects of the present application. Nonionic surfactants having polyoxyethylene groups at multiple terminals include substances obtained by adding ethylene oxide to sorbitan, sorbitan esters, castor oil, hydrogenated castor oil, substances obtained by adding ethylene oxide to polypropylene glycol (i.e., Pluronic (registered trademark) type surfactants), etc.

[0050] The alkyl or alkenyl group constituting the hydrophobic group may be methyl, ethyl, propyl, butyl, hexyl, 2-ethylhexyl, decyl, lauryl, isodecyl, tridecyl, hexadecyl, stearyl, oleyl, behenyl, etc., and may be primary, secondary, or tertiary, and may be a straight chain or have a branched structure.

[0051] Examples of the alkylaryl group constituting the hydrophobic group include tolyl, xylyl, cumyl, octylphenyl, 2-ethylhexylphenyl, nonylphenyl, decylphenyl, and methylnaphthyl. The position and number of the alkyl group are not limited.

[0052] Examples of the polycyclic aromatic group constituting the hydrophobic group include styrylphenyl, styrylmethylphenyl, styrylnonylphenyl, alkylstyrylphenyl, distyrylphenyl, distyrylmethylphenyl, tristyrylphenyl, benzylphenyl, dibenzylphenyl, alkyldiphenyl, diphenyl, cumylphenyl, naphthyl, and bisphenol groups, and the position and number of the substituents are not limited.

[0053] Examples of the higher fatty acids include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, octacosic acid, oleic acid, linoleic acid, linolenic acid, eleostearic acid, ricinoleic acid, erucic acid, coconut oil fatty acid, palm oil fatty acid, palm kernel oil fatty acid, tallow fatty acid, castor oil fatty acid, and rapeseed oil fatty acid.

[0054] From the viewpoint of exerting the effects of the present application, the nonionic surfactant preferably contains an ethylene oxide / propylene oxide copolymer. From the viewpoint of shape retention, the average molecular weight of the nonionic surfactant is preferably 2,000 to 18,000, more preferably 3,000 to 6,000.

[0055] The weight average molecular weight in the present invention is calculated by injecting a sample at a concentration of 3 mg / cc into a separation column KF-402HQ or KF-403HQ manufactured by Showa Denko K.K. using a high-speed gel permeation chromatography apparatus HLC-8220GPC manufactured by TOSOH Co., Ltd. and measuring the peak using a differential refractive index detector.

[0056] Examples of the anionic surfactant include organic carboxylic acids (salts), sulfuric acid ester salts of higher alcohols / higher alcohol ethers, organic sulfonic acid salts, phosphoric acid ester salts of higher alcohols / higher alcohol ethers, etc. Organic sulfuric acid ester salts and organic phosphoric acid ester salts are preferred.

[0057] Specific examples thereof include alkyl sulfates, alkylaryl sulfates, polycyclic aryl sulfates, polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkyl aryl ether sulfates (polyoxyalkylene nonylphenyl ether sulfates, etc.), polyoxyalkylene polycyclic aryl sulfates (polyoxyalkylene tristyryl phenyl ether sulfates, polyoxyalkylene distyryl phenyl ether sulfates, polyoxyalkylene styryl phenyl ether sulfates, polyoxyalkylene styryl phenyl ether sulfates, polyoxyalkylene styryl methyl phenyl ether sulfates, polyoxyalkylene distyryl methyl phenyl ether sulfates, polyoxyalkylene tristyryl methyl phenyl ether sulfates, polyoxyalkylene benzyl phenyl ether sulfates, polyoxyalkylene dibenzyl phenyl ether sulfates, polyoxyalkylene isopropyl phenyl ether sulfates, polyoxyalkylene diisopropyl phenyl ether sulfates, polyoxyalkylene naphthyl ether sulfates, etc.), polyoxyalkylene alkyl polyol ether sulfates Ester salts, alkyl sulfonate salts, α-olefin sulfonate salts, alkyl aryl sulfonate salts, alkyl aryl disulfonate salts (alkyl diphenyl disulfonate salts, etc.), bis (polyoxyalkylene styryl phenyl ether) succinate sulfonate salts, alkyl sulfosuccinate salts, alkyl phosphate ester salts, alkyl aryl phosphate ester salts, polyoxyalkylene alkyl ether phosphate ester salts, polyoxyalkylene alkyl aryl ether phosphate ester salts, polycyclic aryl ether phosphate ester salts, polyoxyalkylene polycyclic aryl ether phosphate ester salts, polyoxyalkylene alkyl polyol ether phosphate ester salts, aromatic sulfonates (alkyl naphthalene sulfonates, naphthalene sulfonates, etc.), aromatic sulfonic acid formaldehyde condensate salts (alkyl naphthalene sulfonic acid formaldehyde condensate salts, naphthalene sulfonic acid formaldehyde condensate salts, creosote sulfonate-based formaldehyde condensates, etc.), melamine sulfonate condensates, bisphenol sulfonate-based condensates, alkyl carboxylate ester salts, polyoxyalkylene alkyl ether carboxylate ester salts, polycarbonate salts, Turkey red oil, lignin sulfonate, etc.

[0058] When the above-mentioned anionic surfactant is a salt, it can be an alkali metal salt, an alkaline earth metal salt, an ammonium salt, an organic amine salt, a quaternary ammonium salt, etc. Alkali metals can be sodium, potassium, lithium, etc. Alkaline earth metals can be magnesium, calcium, barium, etc. Organic amines can be alkylamines (trimethylamine, triethylamine, monomethylamine, dimethylamine, etc.), alkanolamines (monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, dimethylethanolamine, diethylethanolamine, etc.). Quaternary ammonium can be tetramethylammonium, tetraethylammonium, tetramethanolammonium, tetraethanolammonium, etc. These anionic surfactants can be used alone or in combination of two or more.

[0059] Ammonium salts, organic amine salts, and quaternary ammonium salts are preferred because of their excellent affinity with the substrate.

[0060] Examples of the cationic surfactant include quaternary ammonium salt type cationic surfactants (lauryltrimethylammonium chloride, oleylmethylethylammonium ethylsulfate, etc.), amine salt type cationic surfactants (polyoxyethylene laurylamine lactate, etc.), and the like.

[0061] Examples of the amphoteric surfactant include amino acid-based amphoteric surfactants (such as sodium lauryl aminopropionate), betaine-based amphoteric surfactants (such as stearyl dimethyl betaine and lauryl dihydroxyethyl betaine), and the like.

[0062] [Other resins]

[0063] The fiber sizing agent of the present invention may contain at least one selected from the group consisting of vinyl ester resin, saturated polyester resin, unsaturated polyester resin and rosin ester resin. If the total weight ratio of these resins in the non-volatile matter of the sizing agent is less than 20% by weight, the change over time can be suppressed, so it is preferred. The upper limit of the weight ratio is more preferably less than 15% by weight, further preferably less than 10% by weight, and particularly preferably less than 5% by weight. On the other hand, the lower limit of the weight ratio is preferably 0% by weight.

[0064] A resin having a polymerizable double bond in its structure is more preferred because it has excellent shape retention and can improve affinity with the matrix resin. Examples thereof include vinyl ester resins, unsaturated polyester resins, and rosin ester resins.

[0065] Examples of the vinyl ester resin include epoxy (meth) acrylates obtained by esterifying the epoxy resin with an α, β-unsaturated monocarboxylic acid. Examples of the α, β-unsaturated monocarboxylic acid include acrylic acid, methacrylic acid, crotonic acid, tiglic acid, and cinnamic acid, and two or more of these may be used in combination. Specific examples of the vinyl ester resin include bisphenol-type epoxy resin (meth) acrylate-modified products (terminal (meth) acrylate-modified resins obtained by reacting the epoxy group of bisphenol A-type epoxy resin with the carboxyl group of (meth) acrylic acid).

[0066] Examples of the saturated polyester resin include aliphatic polyester resins, aromatic polyester resins, etc. Usually, an aromatic polyester resin such as a polyalkylene arylate resin or a saturated aromatic polyester resin is used.

[0067] Aromatic polyester resins include C2-4 alkylene terephthalates such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); C2-4 alkylene naphthalates corresponding to the alkylene terephthalates (e.g., polyethylene naphthalate); 1,4-cyclohexyldimethyl terephthalate (PCT), etc. Aromatic polyester resins may be copolyesters containing alkylene arylate units as main components (e.g., 50% by weight or more), and the copolymer components may include C2-6 alkylene glycols such as ethylene glycol, propylene glycol, butanediol, and hexanediol, polyoxy C2-4 alkylene glycols, asymmetric aromatic dicarboxylic acids such as phthalic acid and isophthalic acid or their anhydrides, and aliphatic dicarboxylic acids such as adipic acid. Furthermore, a small amount of polyols and / or polycarboxylic acids may be used to introduce a branched structure into the linear polyester. Furthermore, a modified polyester-based resin modified with a modifying compound (for example, an aromatic polyester resin having at least one selected from an amino group and an oxyalkylene group) may also be used. Examples of the modified compound include polyamines (aliphatic diamines such as linear or branched alkylenediamines having about 2 to 10 carbon atoms such as ethylenediamine, trimethylenediamine, propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, trimethylhexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, etc.; alicyclic diamines such as isophoronediamine, bis(4-amino-3-methylcyclohexyl)methane, bis(aminomethyl)cyclohexane, etc.; aromatic diamines such as phenylenediamine, phenylenediamine, diaminodiphenylmethane, etc.), polyols (such as (poly)oxyethylene glycol, (poly)oxytrimethylene glycol, (poly)oxypropylene glycol, (poly)oxytetramethylene glycol, etc.), etc. The modification can be carried out, for example, by heating and mixing the polyester resin and the modified compound and utilizing amidation, esterification, or transesterification reaction.

[0068] The weight average molecular weight of the saturated polyester resin is preferably 3000 to 12000, more preferably 6000 to 11000. The acid value is preferably 5 mgKOH / g or less. The weight of the saturated polyester resin in the non-volatile matter of the sizing agent is preferably less than 20%.

[0069] Unsaturated polyester resins include unsaturated polyesters obtained by reacting an acid component containing an α,β-unsaturated dicarboxylic acid with an alcohol. Examples of α,β-unsaturated dicarboxylic acids include maleic acid, fumaric acid, itaconic acid, and their derivatives such as anhydrides, and two or more of them may be used in combination. In addition, as necessary, α,β-unsaturated dicarboxylic acids may be used in combination with saturated dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, adipic acid, sebacic acid, and their derivatives such as anhydrides as acid components other than α,β-unsaturated dicarboxylic acids. Examples of the alcohol include aliphatic diols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,2-propylene glycol, 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol, alicyclic diols such as cyclopentanediol and cyclohexanediol, hydrogenated bisphenol A, bisphenol A propylene oxide (1 to 100 mol) adducts, aromatic diols such as xylene glycol, and polyols such as trimethylolpropane and pentaerythritol. Two or more of these may be used in combination.

[0070] Specific examples of the unsaturated polyester resin include condensates of fumaric acid or maleic acid and an ethylene oxide (hereinafter referred to as EO) adduct of bisphenol A, condensates of fumaric acid or maleic acid and a propylene oxide (hereinafter referred to as PO) adduct of bisphenol A, and condensates of fumaric acid or maleic acid and EO and PO adducts of bisphenol A (the addition of EO and PO may be random or blocky).

[0071] The weight average molecular weight of the unsaturated polyester resin is preferably 3000 to 12000, more preferably 3000 to 8000. The acid value is preferably 5 mgKOH / g or less. The weight of the unsaturated polyester resin in the non-volatile matter of the sizing agent is preferably less than 20%.

[0072] The rosin ester resin is an esterified product derived from rosin, and examples thereof include a compound obtained by esterifying rosin with a hydroxyl group-containing compound.

[0073] Rosin is a natural resin obtained from pine trees and is a mixture containing abietic acid and its isomers in various proportions. Examples of substances other than abietic acid include dehydroabietic acid, dihydroabietic acid, neoabietic acid, pimaric acid, isopimaric acid, levopimaric acid, and palustric acid.

[0074] The above-mentioned hydroxyl group-containing compound is not particularly limited, and examples thereof include compounds having two hydroxyl groups such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, neopentyl glycol, pentylene glycol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, octanediol, dipropylene glycol and bisphenol A, compounds having three hydroxyl groups such as glycerol, trimethylolethane and trimethylolpropane, compounds having four hydroxyl groups such as pentaerythritol, sorbitan and diglycerol, and compounds having six hydroxyl groups such as sorbitol and dipentaerythritol.

[0075] Rosin esters can also be used as compounds obtained by further adding oxyalkylene oxides such as ethylene oxide or propylene oxide to the above esterified products. The addition of these oxyalkylene oxides can be carried out according to conventional methods. The weight of the rosin ester resin in the non-volatile matter of the sizing agent is preferably less than 20%.

[0076] [Other ingredients]

[0077] From the viewpoint of maintaining the performance of the sizing agent and improving the impartability to the fiber, the fiber sizing agent of the present invention may contain water or an organic solvent, a smoothing agent, an antioxidant, a preservative, etc. as other components within a range that does not hinder the effects of the present invention.

[0078] The water content in the fiber sizing agent of the present invention is not particularly limited, but preferably contains 50 to 95% by weight of water in order to achieve excellent stability and handling properties. The upper limit of the water content in the fiber sizing agent of the present invention is more preferably 75% by weight, and more preferably 70% by weight. On the other hand, the lower limit of the content is more preferably 55% by weight, and more preferably 60% by weight. In addition, for example, it is more preferably 55 to 75% by weight, and more preferably 60 to 70% by weight.

[0079] From the viewpoints of human safety during operation, prevention of disasters such as fire, and prevention of pollution to the natural environment, the fiber sizing agent of the present invention can use organic solvents such as alcohols (methanol, ethanol, isopropanol, etc.), glycols (ethylene glycol, diethylene glycol, propylene glycol, butyl glycol, butyl diglycol, isopropyl glycol, etc.), acetone, and methyl ethyl ketone within the range that does not impair the effects of the present invention.

[0080] In order to improve the handling property of the yarn to which the sizing agent is attached, the fiber sizing agent of the present invention may contain a smoothing agent. Examples of the smoothing agent include esters of higher fatty acids and higher alcohols, natural oils and fats (coconut oil, beef tallow, olive oil, rapeseed oil, etc.), liquid paraffin, wax, etc. Examples of higher fatty acids are shown above. Examples of alkyl groups of higher alcohols are alkyl groups constituting hydrophobic groups shown above. Examples of waxes include polyethylene, polypropylene, oxidized polyethylene, oxidized polypropylene, modified polyethylene, modified polypropylene, paraffin, candelilla wax, carnauba wax, rice bran wax, beeswax, etc.

[0081] The amount of the smoothing agent is preferably 0.1 to 20% by weight, more preferably 1 to 10% by weight, based on the nonvolatile content of the fiber sizing agent.

[0082] From the viewpoint of shape retention and product stability, the lubricant preferably contains fatty acids and / or alcohols having 30 or more carbon atoms, and esters thereof, such as candelilla wax and carnauba wax.

[0083] [Sizing agent for fiber]

[0084] The fiber sizing agent of the present invention contains an epoxy resin (A) and a surfactant (B), and can suppress the hardening of the fiber bundle over time by setting the complex viscosity and loss modulus of the nonvolatile matter of the sizing agent described below within specific ranges.

[0085] The reason why the hardening of the fiber bundle over time can be suppressed is considered to be as follows: by controlling the complex viscosity and loss modulus within specific ranges, the reaction and crosslinking of the epoxy resin (A) alone or with the surfactant (B) and other components are suppressed, the change in the storage modulus and loss modulus over time is moderated, and the increase in the complex viscosity is suppressed, thereby suppressing the hardening over time.

[0086] The fiber sizing agent of the present invention has a complex viscosity of non-volatile matter of 1×10 2 Up to 1×10 4 Pa·s. The upper limit of the complex viscosity is preferably 9×10 3 Pa·s, more preferably 7×10 3 Pa·s, more preferably 5×10 3 Pa·s, particularly preferably 3.0×10 3 Pa·s, the most preferred is 1.0×10 3 On the other hand, the lower limit of the complex viscosity is preferably 1.5×10 2 Pa·s, more preferably 3×10 2 Pa·s, more preferably 5×10 2Pa·s. For example, 1.5×10 2 Up to 9×10 3 Pa·s, more preferably 1.5×10 2 Up to 5×10 3 Pa·s, more preferably 3×10 2 Up to 1×10 3 Pa·s. Less than 1×10 2 Pa·s, the bundling property is insufficient and cannot function as a sizing agent. If it exceeds 1×10 4 Pa·s is too high, and thus the fiber opening property after hardening over time is deteriorated.

[0087] In addition, the non-volatile matter in the present invention is obtained by the method described in the Examples.

[0088] Regarding the fiber sizing agent of the present invention, the loss modulus of the non-volatile matter of the sizing agent at 120°C, strain 1, and frequency 1Hz is 1 to 15Pa. The upper limit of the loss modulus is preferably 14Pa, more preferably 12Pa, further preferably 10Pa, particularly preferably 8Pa, and most preferably 6Pa. On the other hand, the lower limit of the loss modulus is preferably 1.5Pa, more preferably 2Pa, and particularly preferably 2.5Pa. In addition, for example, it is preferably 1.5 to 14Pa, more preferably 2 to 10Pa, and further preferably 2.5 to 6Pa. When it is less than 1Pa, the bundling is insufficient. If it exceeds 15Pa, the fluidity of the sizing agent during drying is low, so the sizing agent is unevenly attached to the carbon fiber, and it is easy to produce local hardening over time, which makes the fiber opening insufficient. In addition, the complex viscosity and loss modulus are measured using a rheometer and the method described in the embodiments.

[0089] From the perspective of composite material properties and the range of complex viscosity and loss modulus of the present invention, the weight ratio of epoxy resin (A) in the non-volatile matter of the fiber sizing agent of the present invention is preferably 20% by weight or more. The lower limit of the weight ratio is more preferably 30% by weight, and more preferably 40% by weight. On the other hand, the upper limit of the weight ratio is preferably 90% by weight, more preferably 80% by weight, and more preferably 70% by weight. In addition, for example, it is preferably 20 to 90% by weight, more preferably 30 to 80% by weight, and more preferably 40 to 70% by weight.

[0090] From the viewpoint of suppressing hardening over time, R in the general formula (1) 1 , R 2 , R 3 and R 4The weight ratio of the bisphenol F type epoxy resin of hydrogen atoms in the non-volatile matter of the fiber sizing agent of the present invention is preferably more than 5 weight %. The lower limit of this weight ratio is more preferably 10 weight %, and more preferably 20 weight %. On the other hand, the upper limit of this weight ratio is preferably 90 weight %, more preferably 80 weight %, and more preferably 70 weight %. In addition, for example, it is preferably 5 to 90 weight %, more preferably 10 to 80 weight %, and more preferably 20 to 70 weight %.

[0091] From the viewpoint of stability of the treatment agent and the viewpoint of easily satisfying the range of complex viscosity and loss modulus of the present invention, the weight ratio of the surfactant (B) in the non-volatile matter of the fiber sizing agent of the present invention is preferably 10% by weight or more. The lower limit of the weight ratio is more preferably 15% by weight, and more preferably 20% by weight. On the other hand, the upper limit of the weight ratio is preferably 40% by weight, more preferably 35% by weight, and more preferably 30% by weight. In addition, for example, it is preferably 10 to 40% by weight, more preferably 15 to 35% by weight, and more preferably 20 to 30% by weight.

[0092] From the viewpoint of stability of the treatment agent, the weight ratio of the surfactant (B) relative to 100 parts by weight of the epoxy resin (A) is preferably 20 to 100 parts by weight. The lower limit of the weight ratio is more preferably 25 parts by weight, and further preferably 30 parts by weight. On the other hand, the upper limit of the weight ratio is preferably 90 parts by weight, more preferably 80 parts by weight, and further preferably 70 parts by weight. In addition, for example, it is more preferably 25 to 90 parts by weight, and further preferably 30 to 80 parts by weight.

[0093] The method for manufacturing the fiber sizing agent of the present invention is not particularly limited, and a known method can be used. Examples include a method of adding the components constituting the sizing agent into water under stirring to form an aqueous solution, an emulsion or an aqueous dispersion; a method of forming an aqueous solution, an emulsion or an aqueous dispersion when manufacturing the components constituting the sizing agent; a method of adding the components constituting the sizing agent into water with a surfactant added under stirring and emulsifying or dispersing the components; a method of mixing the components constituting the sizing agent with a pre-emulsified and dispersed emulsified dispersion; a method of mixing the components constituting the sizing agent and heating the resulting mixture to a temperature above the softening point, and then gradually adding water and performing phase inversion emulsification while applying mechanical shear force using a homogenizer, a homomixer, a ball mill, etc.; a method of mixing the emulsified and dispersed emulsified dispersion in an oil bath for applying the sizing agent, etc.

[0094] The fiber sizing agent of the present invention is self-emulsified and / or emulsified and dispersed in water. The average particle size of the sizing agent is not particularly limited, but is preferably 10 μm or less, more preferably 0.01 to 1 μm, and further preferably 0.01 to 0.5 μm from the viewpoint of shape retention. In addition, the average particle size referred to in the present invention refers to the arithmetic mean value calculated from the particle size distribution measured by a laser diffraction / scattering particle size distribution measuring device (LA-920 manufactured by Horiba).

[0095] The concentration of nonvolatile matter in the fiber sizing agent of the present invention is not particularly limited, but is preferably 5 to 50% by weight, more preferably 10 to 45% by weight, and even more preferably 15 to 40% by weight from the viewpoint of ease of handling.

[0096] Spread 2.0 to 3.0 g of the fiber sizing agent on an aluminum sheet and dry it at 110°C under infrared lamp. When the fluctuation range of the volatile matter in 150 seconds reaches 0.15%, accurately weigh the weight of the residual matter on the aluminum sheet and calculate the ratio (percentage) of the residual weight after heating to the weight before heating, thereby obtaining the non-volatile matter concentration.

[0097] The viscosity of the fiber sizing agent of the present invention at 25° C. is preferably 10 to 100,000 mPa·s, more preferably 10 to 5,000 mPa·s from the viewpoint of handling properties. The viscosity can be measured at a constant temperature of 25° C. using a BL type viscometer.

[0098] From the viewpoint of compounding stability, the pH of the fiber sizing agent of the present invention is preferably 2 to 12, more preferably 4 to 10. The pH can be measured at a constant temperature of 25°C using a pH meter.

[0099] From the viewpoint of cost, etc., the fiber sizing agent of the present invention is preferably circulated at the above-mentioned high concentration, and is circulated at a low concentration (e.g., 0.05 to 5% by weight) when manufacturing a fiber bundle. That is, the transportation cost and storage cost are reduced by circulating at a high concentration, and the fiber is treated at a low concentration, thereby manufacturing a fiber bundle that imparts excellent molded body strength.

[0100] [Fiber yarn]

[0101] The fiber strands of the present invention are obtained by attaching the above-mentioned fiber sizing agent to the raw fiber strands, and are fibers for reinforcing a thermosetting resin or a thermoplastic matrix resin.

[0102] The method for producing a fiber strand of the present invention includes a sizing treatment step of attaching the fiber sizing agent to a raw fiber strand and drying the attached product.

[0103] The method for attaching the fiber sizing agent to the raw fiber strands to obtain the attached product is not particularly limited, and the fiber sizing agent may be attached to the raw fiber strands by a contact roll method, a roll dipping method, a spray method, or other known methods. Among these methods, the roll dipping method is preferred because it can uniformly attach the fiber sizing agent to the raw fiber strands.

[0104] The method for drying the obtained adhered material is not particularly limited, and the adhered material may be dried by heating with, for example, a heating roll, hot air, a hot plate, etc. The drying temperature is not particularly limited, and is, for example, 100 to 250°C.

[0105] In addition, when the fiber sizing agent of the present invention is attached to the raw material fiber strand, all the constituent components of the fiber sizing agent may be mixed and then attached, or the constituent components may be attached in two or more stages. In addition, within the range that does not hinder the effect of the present invention, thermosetting resins such as epoxy resins, vinyl ester resins, and phenolic resins and / or thermoplastic resins such as polyolefin resins other than the polymer component of the present invention, nylon resins, polycarbonate resins, polyester resins, polyacetal resins, ABS resins, phenoxy resins, polymethyl methacrylate resins, polyphenylene sulfide resins, polyetherimide resins, and polyetherketone resins may be attached to the raw material synthetic fiber strand.

[0106] The reinforcing fiber strands of the present invention can be used as reinforcing fibers of composite materials using various thermosetting resins or various thermoplastic resins as matrix resins, and can be used in the form of continuous fibers or cut into specific lengths.

[0107] The amount of nonvolatile matter of the fiber sizing agent attached to the raw fiber strands can be appropriately selected as long as it is an amount necessary for the synthetic fiber strands to have the desired function, but the amount attached is preferably 0.1 to 20% by weight relative to the raw fiber strands. In the fiber strands in the form of continuous fibers, the amount attached is more preferably 0.1 to 10% by weight, and further preferably 0.5 to 5% by weight relative to the raw fiber strands. In addition, in the strands cut to a specific length, the amount attached is more preferably 0.5 to 20% by weight, and further preferably 1 to 10% by weight.

[0108] If the amount of the fiber sizing agent applied is too small, the effect of the present invention related to shape retention is difficult to obtain, and the fiber strands may not be sufficiently bundled, which may result in poor handling. If the amount of the fiber sizing agent applied is too large, the fiber strands may become too rigid, which may result in poor shape retention or poor resin impregnation during composite molding, which is not preferred.

[0109] The fiber of the (raw material) fiber strand to which the fiber sizing agent of the present invention can be applied includes various inorganic fibers such as carbon fiber, glass fiber, ceramic fiber, aramid fiber, polyethylene fiber, polyethylene terephthalate fiber, polybutylene terephthalate fiber, polyethylene naphthalate fiber, polyarylate fiber, polyacetal fiber, PBO fiber, polyphenylene sulfide fiber, polyketone fiber and various organic fibers. From the viewpoint of the physical properties of the obtained fiber-reinforced composite material, it is preferably at least one selected from carbon fiber, aramid fiber, polyethylene fiber, polyethylene terephthalate fiber, polybutylene terephthalate fiber, polyethylene naphthalate fiber, polyarylate fiber, polyacetal fiber, PBO fiber, polyphenylene sulfide fiber and polyketone fiber. More preferably, carbon fiber is used.

[0110] The fiber strands of the present invention are fiber bundles obtained by bundling 3,000 to 100,000 single yarns (filaments) of at least one type selected from the group consisting of these fibers. From the viewpoint of handling and shape retention, it is preferably 10,000 or more, and more preferably 20,000 or more. The synthetic fiber strands of the present invention are sometimes subjected to a fiber opening step to expand the strand width. The fiber opening method may be, for example, friction with a metal surface. The temperature during the fiber opening step is, for example, 20 to 100°C.

[0111] [Fiber-reinforced composite materials]

[0112] The fiber-reinforced composite material of the present invention contains a thermosetting matrix resin or a thermoplastic matrix resin and the above-mentioned reinforcing fiber strands. The reinforcing fiber strands are treated with the fiber sizing agent of the present invention, so the affinity with the reinforcing fiber strands and the matrix resin is good, and a fiber-reinforced composite material with excellent adhesion can be formed.

[0113] The fiber-reinforced composite material of the present invention contains a matrix resin and the above-mentioned fiber strands. The fiber strands are treated with a sizing agent for the fiber of the present invention, the sizing agent is uniformly attached, and has good affinity with the fiber strands and the matrix resin, and can form a fiber-reinforced composite material with excellent adhesion. Furthermore, the thermal decomposition of the sizing agent during high-temperature treatment can be suppressed, and the adhesion hindrance with the matrix resin caused by thermal decomposition can be suppressed. Here, the matrix resin refers to a matrix resin containing a thermosetting resin or a thermoplastic resin, and may contain one or more than two kinds. There is no particular limitation on the thermosetting resin, and epoxy resins, phenolic resins, unsaturated polyester resins, vinyl ester resins, cyanate resins, polyimide resins, etc. can be cited. There is no particular limitation on the thermoplastic resin, and polyolefin resins, polyamide resins, polycarbonate resins, polyester resins, polyacetal resins, ABS resins, phenoxy resins, polymethyl methacrylate resins, polyphenylene sulfide resins, polyetherimide resins, polyether ketone resins, etc. can be cited. Among them, from the viewpoint of a higher adhesiveness-improving effect of the sizing agent for fibers of the present invention, thermosetting resins are preferred, and epoxy resins and vinyl ester resins are more preferred.

[0114] For the purpose of further improving the adhesiveness with the reinforcing fiber strands, these matrix resins may be partially or entirely modified resins.

[0115] The method for producing the fiber-reinforced composite material is not particularly limited, and known methods such as plastic injection molding using short fibers, long fiber pellets, etc., press molding using UD sheets, woven fabric sheets, etc., and other filament winding molding can be used.

[0116] The content of the fiber strands in the fiber-reinforced composite material is not particularly limited and may be appropriately selected depending on the type and morphology of the fibers, the type of the thermoplastic matrix resin, etc., but is preferably 5 to 70% by weight, more preferably 20 to 60% by weight, based on the obtained fiber-reinforced composite material.

[0117] Example

[0118] The present invention is specifically described below by way of examples, but the present invention is not limited to the examples described herein. In addition, the percentages (%) and parts shown in the following examples represent "weight %" and "weight parts" unless otherwise specified. The measurement of each characteristic value is carried out according to the method shown below.

[0119] <Clustering>

[0120] The sizing agent-treated carbon fiber strands were cut into short fibers of about 5 mm using stainless steel scissors, and the bundled state (degree of looseness) at this time was visually determined according to the following criteria.

[0121] ○: Almost the same state as before the staple fibers were cut, and the bundling properties were excellent.

[0122] ×: The short fibers are widely scattered or broken, and the bundling property is poor.

[0123] <Evaluation of fiber opening properties (before aging)>

[0124] The fiber opening property of the sizing agent treated carbon fiber strand (length: about 50 cm) was measured using a texture tester (HANDLE-O-METERHOM-2, manufactured by Daiei Kagaku Seiki Manufacturing Co., Ltd., slit width 5 mm). The measurement was performed 10 times, and the smaller the average value, the better the fiber opening property.

[0125] (Judgment criteria)

[0126] ◎: 50 g or less. The carbon fiber yarn is very soft and has very good fiber opening properties.

[0127] ○: More than 50 g and 60 g or less, the carbon fiber strands are soft and have good fiber opening properties.

[0128] ×: More than 60 g, the carbon fiber yarn is hard and the fiber opening property is poor.

[0129] <Evaluation of fiber opening properties (after time)>

[0130] The sizing agent treated carbon fiber strands (length: about 50 cm) were placed in a thermostat (perfectoven PV-110, manufactured by Tabai ESPEC Co., Ltd.) at 50°C for 1 month and then evaluated using the above fiber opening property measurement method and criteria. In addition, a sizing agent with good fiber opening property after time indicates that the fiber bundle can be prevented from hardening over time.

[0131] <Preparation of Non-volatile Sample of Fiber Sizing Agent>

[0132] 2.0 to 3.0 g of the fiber sizing agent is spread on an aluminum sheet and dried at 110° C. under infrared lamp irradiation. When the fluctuation range of the volatile matter in 150 seconds reaches 0.15%, the residue on the aluminum sheet is taken as the non-volatile matter of the fiber sizing agent.

[0133] <Complex viscosity and loss modulus>

[0134] The complex viscosity and loss modulus of the fiber sizing agent obtained by the above method were measured under the following conditions using a rheometer (HAAKEM ARS40, manufactured by ThermoFisher SCIENTIFIC) as a measurement sample.

[0135] Complex viscosity: sample temperature 25°C, frequency 1 Hz, strain 0.005.

[0136] Loss modulus: After the sample temperature is maintained at 120°C for 1 minute, the sample temperature is 120°C, the frequency is 1 Hz, and the strain is 1.

[0137] The ingredients used in the examples are as follows.

[0138] [Epoxy resin (A)]

[0139] (A1-1): jER (registered trademark) 807 (manufactured by Mitsubishi Chemical Corporation) bisphenol F type epoxy resin (epoxy equivalent: 160 to 175 g / eq)

[0140] (A1-2): Epotohto (registered trademark) YD-128 (manufactured by NIPPON STEEL Chemical & Material Co., Ltd.) bisphenol A type epoxy resin (epoxy equivalent: 184 to 194 g / eq)

[0141] (A1-3): Epotohto (registered trademark) YD-011 (NIPPON STEEL Chemical & Material Co., Ltd.) bisphenol A type epoxy resin (epoxy equivalent: 440 to 510 g / eq)

[0142] (A1-4): DER664U (manufactured by Olin Corporation) bisphenol A type epoxy resin (epoxy equivalent: 875 to 955 g / eq)

[0143] (A1-5): jER (registered trademark) 4005P (manufactured by Mitsubishi Chemical Co., Ltd.) bisphenol F type epoxy resin (epoxy equivalent: 950 to 1200 g / eq)

[0144] (A1-6): jER (registered trademark) 4007P (manufactured by Mitsubishi Chemical Co., Ltd.) bisphenol F type epoxy resin (epoxy equivalent: 2000 to 2500 g / eq)

[0145] (A2): jER (registered trademark) 157S70 (manufactured by Mitsubishi Chemical Co., Ltd.) bisphenol A novolac type epoxy resin (epoxy equivalent: 200 to 220 g / eq)

[0146] (A3): jER (registered trademark) 872 (manufactured by Mitsubishi Chemical Corporation) dimer acid type semi-solid epoxy resin (epoxy equivalent: 600 to 700 g / eq)

[0147] [Surfactant (B)]

[0148] (B-1): Pluronic (registered trademark) P-85 (manufactured by ADEKA Co., Ltd.) POEO polyether

[0149] (B-2): Pluronic (registered trademark) L-121 (manufactured by ADEKA Co., Ltd.) POEO polyether

[0150] (B-3): Pluronic (registered trademark) P-103 (manufactured by ADEKA Co., Ltd.) POEO polyether

[0151] (B-4): Pluronic (registered trademark) F-108 (manufactured by ADEKA Co., Ltd.) POEO polyether

[0152] (B-5): EMULGEN (registered trademark) A-500 (manufactured by Kao Corporation) POE distyrenated phenyl ether

[0153] (B-6): POE hydrogenated castor oil ether (EO50 mol)

[0154] In addition, POEO means polyoxypropylene polyoxyethylene.

[0155] [Other resins]

[0156] (C-1): Unsaturated polyester resin (C-1) shown below

[0157] (C-2): The following saturated polyester resin (C-2)

[0158] (C-3): Unsaturated polyester resin (C-3) shown below

[0159] (C-4): The following saturated polyester resin (C-4)

[0160] (C-5): Ripoxy (registered trademark) VR-60 (manufactured by Showa Denko Co., Ltd.) vinyl ester resin

[0161] (D-1): A compound in which 1 mol of propylene oxide is added to both ends of bisphenol A

[0162] (D-2): 2-Ethylhexyl Stearate

[0163] [Synthesis of unsaturated polyester (C-1)]

[0164] The reactor was purged with nitrogen, 88 parts of maleic anhydride and 404 parts of 4 mol ethylene oxide adduct of bisphenol A were added, reacted at 140°C for 5 hours, and water was distilled off to obtain an unsaturated polyester (C-1) with an acid value of 2.5 mgKOH / g. The weight average molecular weight Mw was 3550.

[0165] [Synthesis of saturated polyester resin (C-2)]

[0166] The reactor was purged with nitrogen, 890 parts of dimethyl isophthalate, 118 parts of dimethyl 5-sulfonate sodium isophthalate, 530 parts of diethylene glycol, 0.5 parts of zinc acetate and 0.5 parts of antimony trioxide were added, reacted at 140 to 220° C. for 5 hours, and diethylene glycol was distilled off at 240 to 270° C. to obtain a saturated polyester resin (C-2) with an acid value of 3.4 mgKOH / g. The weight average molecular weight Mw was 10300.

[0167] [Synthesis of unsaturated polyester resin (C-3)]

[0168] The reactor was purged with nitrogen, 690 parts of 4 mol ethylene oxide adduct of bisphenol A, 154 parts of fumaric acid and 0.3 parts of tetrabutoxy titanate were added, reacted at 170°C for 8 hours, and water was distilled off to obtain an unsaturated polyester (C-3) with an acid value of 3.9 mgKOH / g. The weight average molecular weight Mw was 2120.

[0169] [Synthesis of saturated polyester resin (C-4)]

[0170] The reactor was purged with nitrogen, and 200 parts of terephthalic acid, 490 parts of 4-mol ethylene oxide adduct of bisphenol A, 80 parts of diethylene glycol, 370 parts of polyethylene glycol (average molecular weight 2000), 0.5 parts of zinc acetate and 0.5 parts of antimony trioxide were added and reacted at 140 to 180° C. for 10 hours to obtain a saturated polyester resin (C-4) having an acid value of 8.4 mgKOH / g. The weight average molecular weight Mw was 3300.

[0171] The components other than water shown in Tables 1 to 6 are put into an emulsifying device, slowly added under stirring at 60°C and phase inversion emulsification is performed to obtain a sizing agent aqueous dispersion with a non-volatile concentration of 40% by weight. The obtained sizing agent aqueous dispersion is diluted with water to prepare a sizing agent dilution with a non-volatile concentration of 3% by weight, and the carbon fiber strands (average diameter 8μm, number of filaments 24,000) untreated with the sizing agent are impregnated and impregnated, and then hot-air dried at 120°C for 5 minutes to obtain a sizing agent treated carbon fiber strand with a theoretical attachment amount of 1.0%. The various characteristic values ​​of the present sizing agent and the present strands are evaluated by the above method. The results are shown in Tables 1 to 6.

[0172]

[0173]

[0174]

[0175]

[0176]

[0177]

[0178] As shown in Tables 1 to 6, the fiber sizing agents of Examples 1 to 40 contain epoxy resin (A) and surfactant (B), and the complex viscosity of the non-volatile matter of the sizing agents at 25°C, strain 0.005, and frequency 1 Hz is 1×10 2 Up to 1×10 4 The loss modulus of the nonvolatile matter of the sizing agent at 120° C., strain 1, and frequency 1 Hz is 1 to 15 Pa, so that the hardening of the fiber bundle over time can be suppressed.

[0179] On the other hand, since the complex viscosity is not 1×10 2 Up to 1×10 4 When the viscosity is within the range of Pa·s (Comparative Examples 3 and 9 to 11), when the loss modulus is not within the range of 1 to 15 Pa (Comparative Examples 2, 7 and 8), when both the complex viscosity and the loss modulus are not within the range (Comparative Examples 1, 4 to 6), and when the epoxy resin (A) is not contained (Comparative Examples 12 and 13), the bundling property is insufficient and it cannot be used as a sizing agent, and the problem of suppressing the hardening of the fiber bundle over time cannot be solved.

[0180] Industrial Applicability

[0181] Fiber-reinforced composite materials in which a matrix resin is reinforced with reinforcing fibers can be used for automotive applications, aviation and aerospace applications, sports and leisure applications, general industrial applications, etc. Examples of reinforcing fibers include various inorganic fibers such as carbon fibers, glass fibers, and ceramic fibers, and various organic fibers such as aramid fibers, polyamide fibers, and polyethylene fibers.

Claims

1. A fiber sizing agent comprising an epoxy resin (A) and a surfactant (B), The complex viscosity of the non-volatile matter of the sizing agent at 25°C, strain 0.005, and frequency 1 Hz is 1×10 2 Pa·s to 1×10 4 Pa·s, The loss modulus of the non-volatile matter of the sizing agent at 120° C., strain 1, and frequency 1 Hz is 1 Pa to 15 Pa.

2. The fiber sizing agent according to claim 1, wherein The epoxy resin (A) contains a compound (a1) represented by the following general formula (1): (1) In formula (1), R 1 , R 2 , R 3 and R 4 Each independently represents a hydrogen atom or a methyl group, and n is an integer greater than 0.

3. The fiber sizing agent according to claim 2, wherein The weight ratio of the epoxy resin (A) in the non-volatile matter of the sizing agent is 20 weight % or more, and the compound (a1) contains a compound in which n is 2 or more.

4. The fiber sizing agent according to claim 2 or 3, wherein The compound (a1) contains the R 1 , R 2 , R 3 and R 4 A compound containing hydrogen atoms.

5. The fiber sizing agent according to any one of claims 1 to 4, wherein The total content of the vinyl ester resin, the saturated polyester resin, the unsaturated polyester resin and the rosin ester resin in the non-volatile matter of the sizing agent is 20% by weight or less. 6 . A fiber strand material to which the fiber sizing agent according to claim 1 is attached.

7. A fiber-reinforced composite material comprising a matrix resin and the fiber strands according to claim 6.

8. The fiber-reinforced composite material according to claim 7, wherein: The matrix resin is a thermosetting resin.

Images