JP2023169089A - Sizing agent composition for fiber and sizing agent solution for fiber - Google Patents

Abstract

To provide a fiber sizing agent that exhibits superior sizing properties and ensures superior adhesion between fiber and matrix resin.SOLUTION: A sizing agent composition for fiber contains a bisphenol type epoxy resin (A) represented by the general formula (1), and a nonionic surfactant (B). The bisphenol type epoxy resin (A) includes at least an epoxy resin (A1), where n in the general formula (1) is 0 or 1, and an epoxy resin (A2), where n in the general formula (1) is 2 or more. For each molecule of the bisphenol type epoxy resin (A), n in the general formula (1) is 20 or less. When the total weight of the epoxy resin (A1), where n in the general formula (1) is 0 or 1, is defined as W1, and the total weight of the epoxy resin (A2), where n in the general formula (1) is 2 or more, is defined as W2, the ratio between them (W1/W2) is 15/85-90/10.SELECTED DRAWING: None

Description

The present invention relates to a sizing agent composition for fibers and a sizing agent solution for fibers.

In recent years, composite materials of matrix resins such as unsaturated polyester resins, phenolic resins, epoxy resins, and polypropylene resins and various fibers have been widely used in fields such as sports equipment, leisure goods, and aircraft. In these composite materials, fibers such as glass fibers, carbon fibers, ceramic fibers, metal fibers, mineral fibers, rock fibers, and slag fibers are used. A sizing agent is usually added to these fibers during the processing step to form the composite material (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2013-249562

In order to improve the physical properties of composite materials, it is important to have high adhesion between the fibers and the matrix resin in order to make effective use of the characteristics of the fibers, and to have excellent cohesiveness in terms of the ease of handling the fiber bundles.
However, conventional techniques have not been able to sufficiently improve the above-mentioned characteristics, and there is still room for improvement.

An object of the present invention is to provide a sizing agent for fibers that has excellent sizing properties and excellent adhesiveness between fibers and matrix resin.

The present inventor has arrived at the present invention as a result of studies to achieve the above object.
That is, the present invention provides a sizing agent composition for fibers containing a bisphenol-type epoxy resin (A) represented by the following general formula (1) and a nonionic surfactant (B), The resin (A) contains at least an epoxy resin (A1) in which n in the following general formula (1) is 0 or 1, and an epoxy resin (A2) in which n in the following general formula (1) is 2 or more. , n in the following general formula (1) per molecule of bisphenol type epoxy resin (A) is 20 or less, and the total weight W1 of the epoxy resin (A1) in which n in the following general formula (1) is 0 or 1. and a fiber sizing agent composition in which the ratio (W1/W2) of the epoxy resin (A2) in which n in the following general formula (1) is 2 or more to the total weight W2 is 15/85 to 90/10; This is a sizing agent solution for fibers in which a sizing agent composition for fibers is dissolved or dispersed in a solvent containing one or more selected from the group consisting of water and an organic solvent.

［式中、Ｒ^１はそれぞれ独立に水素原子、炭素原子数１～４のアルキル基または炭素原子数１～４のアルコキシ基であり、Ｒ^２はそれぞれ独立にメチレン基又はイソプロピリデン基のいずれかで表される構造部位であり、ｎは０以上の整数である。］

[In the formula, R ¹ is each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R ² is each independently a methylene group or an isopropylidene group. is a structural site represented by , where n is an integer of 0 or more. ]

According to the present invention, it is possible to provide a sizing agent for fibers that has excellent sizing properties and excellent adhesiveness between fibers and matrix resin.

<Fiber sizing agent composition>
The fiber sizing agent composition of the present invention contains a bisphenol-type epoxy resin (A) represented by the following general formula (1) and a nonionic surfactant (B).

In the general formula (1), R ¹ is each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a straight-chain or branched propyl group, and a straight-chain or branched butyl group. Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, a straight-chain or branched propoxy group, and a straight-chain or branched butoxy group. Preferably, R ¹ is a hydrogen atom.

In general formula (1), R ² is a structural moiety each independently represented by either a methylene group or an isopropylidene group. R ² is preferably a methylene group.

n in general formula (1) is the number of groups in parentheses in general formula (1), and is an integer of 0 or more. n in general formula (1) per molecule of bisphenol type epoxy resin (A) is 20 or less.

In the present invention, the bisphenol type epoxy resin (A) includes at least an epoxy resin (A1) in which n in the general formula (1) is 0 or 1, and an epoxy resin (A1) in which n in the following general formula (1) is 2 or more ( A2). Further, in the present invention, the ratio (W1/W2) of the total weight W1 of the epoxy resin (A1) to the total weight W2 of the epoxy resin (A2) is 15/85 to 90/10. In the following, "bisphenol type epoxy resin (A)" is also referred to as "component (A)."

By containing the epoxy resin (A1) and the epoxy resin (A2) in a weight ratio (W1/W2) of 15/85 to 90/10, component (A) has excellent focusing properties and Adhesion between fibers and matrix resin can be sufficiently improved.
If the weight ratio (W1/W2) of the epoxy resin (A1) and the epoxy resin (A2) in component (A) is less than 15/85, the adhesiveness between the fiber and the matrix resin will be insufficient. If the weight ratio exceeds 90/10, the convergence may become insufficient.

The weight ratio (W1/W2) of the epoxy resin (A1) and the epoxy resin (A2) in component (A) is preferably 20/80 or more, from the viewpoint of adhesiveness between the fibers and the matrix resin. More preferably, it is 25/75 or more, and from the viewpoint of convergence, it is preferably 89/11 or less, and more preferably 75/25 or less.

From the viewpoint of having excellent focusing properties, component (A) contains an epoxy resin in which the epoxy resin (A1) is 0 in the general formula (1), and the epoxy resin (A2) is in the general formula (1). A preferred embodiment includes an epoxy resin in which n is 2 and an epoxy resin in which n in the general formula (1) is 4 or more. In other words, the bisphenol type epoxy resin (A) includes an epoxy resin in which n in the general formula (1) is 0, an epoxy resin in which n in the general formula (1) is 2, and an epoxy resin in which n in the general formula (1) is 2. An embodiment containing four or more epoxy resins is preferred.

In the present invention, the bisphenol-type epoxy resin (A) is preferably an epoxy resin formed by condensing diglycidyl ether of a bisphenol compound (for example, bisphenol A, bisphenol F, bisphenol S, etc.) and epihalohydrin (for example, epichlorohydrin, etc.). More preferably, it is a bisphenol A type epoxy resin formed by condensing bisphenol A and epichlorohydrin.

The bisphenol-type epoxy resin (A) preferably contains a bisphenol-type epoxy resin (Ax) having an Mn of 350 to 1200 from the viewpoint of suppressing fluffing of the fiber bundle. When the bisphenol-type epoxy resin (A) contains a bisphenol-type epoxy resin (Ax) with Mn of 350 to 1200, the total weight of the bisphenol-type epoxy resin with Mn of 350 to 1200 is based on the total weight of the bisphenol-type epoxy resin (A). It is preferably 60% by weight or more, more preferably 65% by weight or more.

The number average molecular weight (Mn) of the bisphenol type epoxy resin (A) can be measured at 40°C by gel permeation chromatography (hereinafter referred to as GPC).
GPC measurement conditions can be set as follows, for example.
(GPC measurement conditions)
Model: Alliance (liquid chromatograph manufactured by Nippon Waters Co., Ltd.)
Column: Guardcolumn Super HL
+TSK gel Super H4000
+TSK gel Super H3000
+TSK gel Super H2000
(Both manufactured by Tosoh Corporation)
Column temperature: 40℃
Detector: RI (Refractive Index)
Eluent: Tetrahydrofuran Eluent flow rate: 0.6ml/min Sample concentration: 0.25% by weight
Injection volume: 10μl
Standard material:
Molecular weight = 228 (Idemitsu Kosan Co., Ltd.; bisphenol A)
Molecular weight = 340 (manufactured by Mitsui Chemicals Fine Co., Ltd.; Epomic R139S)
Molecular weight = 370 (manufactured by Mitsubishi Chemical Corporation; jER828)
Molecular weight = 470 (manufactured by Mitsubishi Chemical Corporation; jER834)
Molecular weight = 900 (manufactured by Mitsubishi Chemical Corporation; jER1001)
Molecular weight = 1200 (manufactured by Mitsubishi Chemical Corporation; jER1002)

The bisphenol type epoxy resin (A) includes, for example, an epoxy resin (A1) in which n in the general formula (1) is 0 or 1, and an epoxy resin (A2) in which n in the general formula (1) is 2 or more. can be produced by a method of blending and mixing so that the weight ratio (W1/W2) is 15/85 to 90/10.

The epoxy resin (A1) and the epoxy resin (A2) are prepared by mixing a resin containing the epoxy resin (A1) and the epoxy resin (A2) (for example, epoxy resin "jER1001" manufactured by Mitsubishi Chemical) with a solvent (for example, tetrahydrofuran, etc.). ), and fractionated according to molecular weight using a GPC fractionator [for example, recycle preparative HPLC, "LC-9130NEXT" manufactured by Japan Analytical Industry Co., Ltd.].

The epoxy resin (A1) and the epoxy resin (A2) may be manufactured using various bisphenol compounds, epihalohydrin, and the like. Specific production methods include, for example, a method in which a diglycidyl ether compound obtained by reacting a bisphenol compound and epihalohydrin is further reacted with a bisphenol compound (Method 1), and a method in which a bisphenol compound and epihalohydrin are reacted directly. Examples include a method (method 2) for obtaining the target epoxy resin. Method 1 is preferred because the reaction is easy to adjust and n [the number of groups in parentheses in general formula (1)] of the resulting epoxy resin can be easily adjusted.

As the bisphenol compound used in method 1 or 2, for example, a compound represented by the following general formula (1a) can be used. As the epihalohydrin, epichlorohydrin or the like can be used.

In formula (1a), R ¹ and R ² are respectively the same as R ¹ and R ² in general formula (1). The compound represented by the general formula (1a) can be selected depending on the type of the target bisphenol-type epoxy resin [the compound represented by the general formula (1)].

In the present invention, nonionic surfactants (B) include, for example, alkylene oxide (AO) adducts (Mn = 158 to 200,000) of aliphatic monohydric alcohols (8 to 18 carbon atoms), polyvalent ( AO adducts (Mn 500-100,000) of divalent (2-8) alcohols (2-6 carbon atoms; ethylene glycol, propylene glycol, glycerin, pentaerythritol, sorbitan, etc.), AO of higher fatty acids (12-24 carbon atoms) Adducts (Mn = 158 to 200,000), AO adducts of alkylphenols (carbon numbers 10 to 20) (Mn 500 to 5,000), AO adducts of arylalkylphenols (carbon numbers 14 to 62; styrenated phenols, etc.) Adduct (Mn 500-5,000), AO adduct (Mn 500-5,000) of styrenated cumylphenol or styrenated cresol (total number of carbon atoms 15-61), polyalkylene glycol (Mn 150-6,000) ) with a fatty acid having 12 to 24 carbon atoms, polyhydric (bivalent to octavalent, or more) alcohol (carbon number 2 to 32, such as ethylene glycol, propylene glycol, glycerin, pentaerythritol, sorbitan) etc.) and fatty acids having 12 to 24 carbon atoms (e.g. lauric acid, stearic acid), AO adducts of esters (Mn 350 to 10,000), AO adducts of fatty acid amides having 12 to 24 carbon atoms (Mn 200 to 30, 000), polyvalent (divalent to octavalent or more) alcohol alkyl (carbon number 8 to 60) ether adduct (Mn 220 to 30,000), and the like.
Examples of alkylene oxide (AO) include ethylene oxide (EO), propylene oxide (PO), and butylene oxide (BO). PO and BO may be linear or branched. AO may be used alone or in combination of two or more. Examples of AO adducts that are a combination of two or more types include random adducts, block adducts, and mixed adducts thereof.

Among the nonionic surfactants (B), from the viewpoint of focusing properties, arylalkylphenols {styrenated phenol (14 to 62 carbon atoms), styrenated cumylphenol, and styrenated cresol (15 to 61 carbon atoms) are preferable. AO adducts of styrenated phenols (Mn 500 to 5,000), more preferably AO adducts of arylalkylphenols, more preferably AO adducts of styrenated phenols, particularly preferably PO and styrenated phenols. It is an EO adduct.
The nonionic surfactants (B) may be used alone or in combination of two or more.

The method for measuring Mn of the nonionic surfactant (B) is the same as the method for measuring Mn of the bisphenol type epoxy resin (A) described above, except that polyethylene glycol is used as the standard substance.

In the fiber sizing agent composition of the present invention, the ratio (Wb/Wa) to the weight Wa of the bisphenol-type epoxy resin (A) to the weight Wb of the nonionic surfactant (B) is determined by the fuzzing suppressing effect and the adhesion improving effect. From the viewpoint of coexistence, the ratio is preferably 5/95 to 50/50, more preferably 10/90 to 30/70, and even more preferably 20/80 to 35/65.

The content of the bisphenol-type epoxy resin (A) in the sizing agent composition for fibers of the present invention is determined by the weight of the solid content contained in the sizing agent composition for fibers, from the viewpoint of achieving both a fluffing suppressing effect and an effect of improving adhesiveness. Based on the above, 50 to 95% by weight is preferred, and 70 to 90% by weight is more preferred. Here, the solid content is the residue after heating and drying 1 g of the sample at 130° C. for 45 minutes in a circulating dryer.

The content of the nonionic surfactant (B) in the sizing agent composition for fibers of the present invention is determined based on the solid content of the sizing agent composition for fibers, from the viewpoint of achieving both a fluffing suppressing effect and an effect of improving adhesiveness. Based on weight, 5 to 50% by weight is preferred, and 10 to 30% by weight is more preferred.

The fiber sizing agent composition of the present invention may contain components other than the bisphenol-type epoxy resin (A) and the nonionic surfactant (B). Other components include surfactants (C) other than nonionic surfactants, smoothing agents, preservatives, antioxidants, and the like.

Surfactants (C) other than nonionic surfactants include known surfactants such as anionic surfactants, cationic surfactants, and amphoteric surfactants (for example, JP 2006-124877A, WO 2003/37964). (mentioned in the No. 1 publication), etc.
Smoothing agents include waxes (polyethylene, polypropylene, polyethylene oxide, polypropylene oxide, modified polyethylene, modified polypropylene, etc.), higher fatty acid alkyl (1 to 24 carbon atoms) esters (methyl stearate, ethyl stearate, proprustearate, etc.). stearate, butyl stearate, octyl stearate, stearyl stearate, etc.), higher fatty acids (myristic acid, palmitic acid, stearic acid, etc.), natural fats and oils (coconut oil, beef tallow, olive oil, rapeseed oil, etc.), and liquid paraffin. It will be done.
Examples of preservatives include benzoic acids, salicylic acids, sorbic acids, quaternary ammonium salts, imidazoles, and the like.
Examples of antioxidants include phenols (2,6-di-t-butyl-p-cresol, etc.), thiodipropionates (dilauryl 3,3'-thiodipropionate, etc.), and phosphites (triphenyl phosphite, etc.).

The content of other components in the sizing agent composition for fibers of the present invention is preferably 0 to 5% by weight based on the weight of solid content contained in the sizing agent composition for fibers from the viewpoint of excellent sizing properties. , more preferably 0 to 2% by weight.

Although there are no particular limitations on the method for producing the fiber sizing agent composition of the present invention, for example, a bisphenol-type epoxy resin (A) and a nonionic surfactant (B), as well as the components to be used as necessary (as described above), are placed in a mixing container. Examples include a method in which the mixture is stirred until homogeneous, preferably at 20 to 150°C, more preferably at 50 to 120°C. There is no particular restriction on the order in which the components [(A), (B) and other components] constituting the composition are added.

<Fiber sizing agent solution>
The fiber sizing agent solution of the present invention is obtained by dissolving or dispersing the fiber sizing agent composition of the present invention in a solvent containing one or more types selected from the group consisting of water and an organic solvent.
By dissolving or dispersing the fiber sizing agent composition of the present invention in a solvent, it becomes easy to control the amount of the fiber sizing agent composition attached to the fiber bundle in an appropriate amount.

Examples of the solvent include water and organic solvents.
Examples of organic solvents include monohydric alcohols having 1 to 4 carbon atoms (methanol, ethanol, isopropanol, etc.), ketones having 3 to 6 carbon atoms (acetone, ethyl methyl ketone, methyl isobutyl ketone, etc.), and 2 to 4 carbon atoms. 6 glycol (ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, etc.), its mono-lower alkyl (alkyl has 1 to 4 carbon atoms) ether, dimethylformamide, aromatic hydrocarbon (toluene, xylene, etc.), carbon number Examples include 3 to 5 acetic acid alkyl esters (methyl acetate, ethyl acetate, etc.).
The above-mentioned solvents may be used alone or in combination of two or more. Among the above-mentioned solvents, water and water-miscible organic solvents (mixed uniformly with water at a volume ratio of 1:1 at 25°C) are preferable from the viewpoint of fire safety, etc. A mixed solvent of water and an organic solvent that can be used is water, and water is more preferred.

From the viewpoint of cost and the like, the fiber sizing agent solution of the present invention preferably has a high concentration during distribution and a low concentration during production of fiber bundles. That is, by distributing the fibers at a high concentration, transportation costs, storage costs, etc. can be reduced, and by processing the fibers at a low concentration, it is possible to manufacture fiber bundles that have both excellent bundling and opening properties.
The concentration (weight ratio of components other than the solvent) of the fiber sizing agent solution during distribution is preferably 30 to 80% by weight, more preferably 40 to 70% by weight, from the viewpoint of storage stability and the like.
The concentration of the fiber sizing agent solution during production of the fiber bundle is preferably 0.5 to 15% by weight, from the viewpoint that the amount of the fiber sizing agent deposited can be set to an appropriate amount during production of the fiber bundle. More preferably, it is 1 to 10% by weight.

Although there are no particular limitations on the method for producing the fiber sizing agent solution of the present invention, for example, a solvent may be added to the fiber sizing agent composition of the present invention to dissolve or emulsify and disperse the fiber sizing agent composition in the solvent. One example is how to
The temperature at which the fiber sizing agent composition is dissolved or emulsified in a solvent is preferably 20 to 90°C, more preferably 40 to 90°C, from the viewpoint of ease of mixing. The time for dissolving or emulsifying and dispersing the fiber sizing agent composition in a solvent is preferably 1 to 20 hours, more preferably 1 to 10 hours.
When dissolving or emulsifying and dispersing the fiber sizing agent composition in a solvent, known mixing devices, dissolving devices, and emulsifying and dispersing devices can be used. and three-stage paddle, etc.), Nauta mixer [manufactured by Hosokawa Micron Co., Ltd., etc.], ribbon mixer, conical blender, mortar mixer, universal mixer {universal mixer "5DM-L" [manufactured by Sanei Seisakusho Co., Ltd.], etc. }, a Henschel mixer [Nippon Coke Industry Co., Ltd., etc.], an autoclave, etc. can be used.

The fibers to which the fiber sizing agent composition or fiber sizing agent solution of the present invention can be applied include inorganic fibers (carbon fibers, glass fibers, ceramic fibers, metal fibers, mineral fibers, slag fibers, etc.) and organic fibers (aramid fibers, etc.). etc.). From the viewpoint of the strength of the fiber sizing agent composition and the composite material molded body using the fibers, carbon fibers are preferred among these.

Examples of methods for treating fibers with the fiber sizing agent composition or fiber sizing agent solution of the present invention include a spray method and a dipping method. The amount of the fiber sizing agent composition deposited on the fiber is preferably 0.05 to 5% by weight, more preferably 0.2 to 2.5% by weight, based on the weight of the fiber, from the viewpoint of sizing property. Weight%.

A fiber bundle obtained by treating the fibers with the fiber sizing agent composition or fiber sizing agent solution of the present invention may be processed into a textile product. Textile products include woven fabrics, knitted fabrics, nonwoven fabrics (felt, mats, paper, etc.), chopped fibers, milled fibers, and the like.

The fiber bundle and/or textile product obtained by treatment with the fiber sizing agent composition or fiber sizing agent solution of the present invention may be combined with a matrix resin to form a composite material.
Matrix resins include thermoplastic resins (polypropylene, polyamide, polyethylene terephthalate, polycarbonate, polyphenylene sulfide, etc.), thermosetting resins [similar to epoxy resins, unsaturated polyester resins, and vinyl ester resins], and phenolic resins (patent No. No. 3,723,462, etc.), etc.).

In the composite material, the weight ratio between the matrix resin and the fiber bundle (matrix resin/fiber bundle) is preferably 10/90 to 90/10, more preferably 20 /80 to 70/30, particularly preferably 30/70 to 60/40. The composite material may also include a catalyst.

The composite material is made by combining a matrix resin that has been thermally melted (preferably melting temperature: 60 to 350°C) or diluted with a solvent (acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, ethyl acetate, etc.) to fiber bundles and/or matrix resin. Alternatively, it can be manufactured by impregnating textile products. When a solvent is used, it is preferable to dry the prepreg to remove the solvent.

When the matrix resin constituting the composite material is a thermoplastic resin, a molded article can be obtained by heat-molding the prepreg and solidifying it at room temperature.
When the matrix resin constituting the composite material is a thermosetting resin, a molded article can be obtained by heat-molding the prepreg and curing it.
Although these resins do not need to be completely cured, they are preferably cured to an extent that the molded article can maintain its shape. After molding, it may be further heated to be completely cured.
The method of thermoforming is not particularly limited, and may be a known method, such as a filament winding method (a method of winding a rotating mandrel while applying tension and heat forming), a press molding method (a method of laminating prepreg sheets and heat forming them). ), an autoclave method (a method in which a prepreg sheet is heated and molded by pressing it against a mold), and a method in which chopped fibers or milled fibers are mixed with a matrix resin and injection molded.

The present invention will be further explained below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Hereinafter, parts refer to parts by weight unless otherwise specified.
In this example, Mn of the epoxy resin was measured by the following method.

<Method for measuring Mn of epoxy resin>
Mn of the epoxy resin was measured by GPC at 40°C using the following standard substance.
The GPC measurement conditions are as follows.
(GPC measurement conditions)
Model: Alliance (liquid chromatograph manufactured by Nippon Waters Co., Ltd.)
Column: Guardcolumn Super HL
+TSK gel Super H4000
+TSK gel Super H3000
+TSK gel Super H2000
(Both manufactured by Tosoh Corporation)
Column temperature: 40℃
Detector: RI (Refractive Index)
Eluent: Tetrahydrofuran Eluent flow rate: 0.6ml/min Sample concentration: 0.25% by weight
Injection volume: 10μl
Standard material:
Molecular weight = 228 (Idemitsu Kosan Co., Ltd.; bisphenol A)
Molecular weight = 340 (manufactured by Mitsui Chemicals Fine Co., Ltd.; Epomic R139S)
Molecular weight = 370 (manufactured by Mitsubishi Chemical Corporation; jER828)
Molecular weight = 470 (manufactured by Mitsubishi Chemical Corporation; jER834)
Molecular weight = 900 (manufactured by Mitsubishi Chemical Corporation; jER1001)
Molecular weight = 1200 (manufactured by Mitsubishi Chemical Corporation; jER1002)

<Production Example 1: Production of bisphenol type epoxy resin>
400 g of Mitsubishi Chemical's epoxy resin "jER1001" was dissolved in tetrahydrofuran to a solid content concentration of 2%, and the mixture was dissolved using a GPC preparative device [recycle preparative HPLC, "LC-9130NEXT" manufactured by Japan Analytical Industry Co., Ltd.]. The epoxy resin was fractionated according to molecular weight. Thereafter, each fractionated liquid was charged into a reaction vessel equipped with a heating/cooling device and a stirring device, and the pressure was gradually reduced to 20 mmHg at 90°C to remove tetrahydrofuran. Epoxy resin (A-1) (molecular weight 340), bisphenol epoxy resin (A-2) (molecular weight 624) where n is 1, bisphenol epoxy resin (A-3) where n is 2 (molecular weight 908), A bisphenol-type epoxy resin (A-4) of No. 3 (molecular weight 1192) and a bisphenol-type epoxy resin (A-5) with n of 4 or more and 10 or less (Mn of 1476 or more) were obtained. Epoxy resins (A-1) to (A-5) are each a compound in which R ¹ in the general formula (1) is a hydrogen atom and R ² is an isopropylidene group.

<Examples 1 to 7, Comparative Examples 1 to 7>
Epoxy resin (A) and nonionic surfactant (B-1) of the type and amount (parts by weight) listed in Table 1 [propylene oxide ethylene oxide adduct of styrenated phenol [trade name "Soprophor 796/P"] Solvay Nicca Co., Ltd.] was uniformly dissolved for 30 minutes in a universal mixer [all-purpose mixer, manufactured by Sanei Seisakusho Co., Ltd.] while controlling the temperature at 60°C, and then water was poured there for 6 hours. The sizing agent solutions for fibers (Y-1) to (Y-7) of Examples with a solid content concentration of 40% by weight and the sizing agent solutions for fibers of Comparative Examples (Y'-1) to (Y' -7) were obtained, 25 parts each.

Using the fiber sizing agent solutions (Y-1) to (Y-7) and (Y'-1) to (Y'-7) of Examples and Comparative Examples, carbon fiber bundles were produced by the following method, The focusing properties and interfacial shear strength were evaluated. The results are shown in Table 1.

<Manufacture of carbon fiber bundles for evaluation tests>
Water is added to the fiber sizing agent solution of each example to make a dispersion liquid so that the solid content concentration is 1.5% by weight, and untreated carbon fibers (12,000 filaments) are immersed in the fiber sizing agent solution. and impregnated with a dispersion of the agent composition. Thereafter, the carbon fibers were taken out from the dispersion of the fiber sizing agent composition and dried with hot air at 180° C. for 3 minutes to obtain a carbon fiber bundle. The carbon fiber bundles were prepared such that the amount of solid content contained in the dispersion of the fiber sizing agent composition attached to the fibers (percentage based on the weight of carbon fibers before dipping) was 1.5% by weight. . The carbon fiber bundle was subjected to evaluation tests for cohesiveness and interfacial shear strength.

<Convergence evaluation test>
Using a carbon fiber bundle for testing, the focusing property was evaluated according to JIS L1096-2010 8.21.1 A method (45° cantilever method). The carbon fiber bundles obtained under the processing conditions specified by JIS were evaluated using a cantilever. The larger the measured value (cm), the better the focusing ability. The convergence value measured by this evaluation method is preferably 13 cm or more.

<Evaluation test of interfacial shear strength>
Interfacial shear strength was evaluated by microdroplet test.
A single yarn was taken out from the carbon fiber bundle and set in a sample holder. As the matrix resin, an epoxy resin [jER828 (product name) manufactured by Mitsubishi Chemical Corporation] was used, and 100 parts by mass of the resin and 45 parts by mass of a curing agent [amine-based curing agent Jeffermine T-403 (product name) manufactured by Huntsman Co., Ltd.] were used. A sample for measurement was obtained by coating the mixture on carbon fiber single yarn to form a drop and curing at 80° C. for 180 minutes. The measurement was carried out using a composite material interface property evaluation device HM410 [manufactured by Toei Sangyo Co., Ltd.], and the maximum pulling load F was measured when a drop was pulled out from a single yarn by running at a speed of 0.12 mm/min. The interfacial shear strength τ was calculated using the following formula, and the interfacial shear strength between the single fiber and the matrix resin was evaluated. The larger the value of the interfacial shear strength, the better the adhesion between the fiber and the matrix resin. The interfacial shear strength is preferably 55 MPa or more.
Interfacial shear strength τ (unit: MPa) = F/πdl
(F: Maximum pulling load, d: Single yarn diameter, l: Particle diameter in the drop pulling direction)

As shown in Table 1, it was found that when the fiber sizing agent solution of the example was used, excellent sizing properties and interfacial shear strength could be obtained. This shows that, according to the present invention, it is possible to provide a sizing agent for fibers that has excellent sizing properties and excellent adhesiveness between fibers and matrix resin.

The present invention will be further explained below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Hereinafter, parts refer to parts by weight unless otherwise specified.
In this example, Mn of the epoxy resin was measured by the following method. Note that Examples 1, 2, 3, 4, and 7 are Reference Examples 1, 2, 3, 4, and 5, respectively.

Claims (4)

A fiber sizing agent composition containing a bisphenol-type epoxy resin (A) represented by the following general formula (1) and a nonionic surfactant (B),
The bisphenol type epoxy resin (A) is at least an epoxy resin (A1) in which n in the following general formula (1) is 0 or 1, and an epoxy resin (A2) in which n in the following general formula (1) is 2 or more. n in the following general formula (1) per molecule of bisphenol type epoxy resin (A) is 20 or less,
Ratio of the total weight W1 of the epoxy resin (A1) in which n is 0 or 1 in the following general formula (1) to the total weight W2 of the epoxy resin (A2) in which n is 2 or more in the following general formula (1) A sizing agent composition for fibers having a ratio (W1/W2) of 15/85 to 90/10.

[In the formula, R ¹ is each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and R ² is each independently a methylene group or an isopropylidene group. is a structural site represented by , where n is an integer of 0 or more. ] The bisphenol type epoxy resin (A) includes an epoxy resin in which n in the general formula (1) is 0, an epoxy resin in which n in the general formula (1) is 2, and an epoxy resin in which n in the general formula (1) is 4. The sizing agent composition for fibers according to claim 1, comprising the above epoxy resin. Claim 1 or 2, wherein the total weight of the bisphenol epoxy resins having a number average molecular weight of 350 to 1200 in the bisphenol epoxy resin (A) is 60% by weight or more based on the total weight of the bisphenol epoxy resin (A). The fiber sizing agent composition described above. A sizing agent solution for fibers, which is obtained by dissolving or dispersing the sizing agent composition for fibers according to claim 1 or 2 in a solvent containing one or more types selected from water and organic solvents.