KR20160077322A - A carbon-fiber for filament winding bundle - Google Patents

Abstract

The present invention provides a carbon fiber bundle for filament winding, which is high in the strength conversion ratio of a raw carbon fiber thread, in other words, improved in strength of final composite materials. The present invention relates to a carbon fiber sizing agent and the carbon fiber bundle coated on the surface of the carbon fiber with the sizing agent, wherein the carbon fiber sizing agent includes: resin composed of 75-90 mass% of epoxy resin, 5-25 mass% of ester resin, and 3-5 mass% of phenoxy resin with respect to 100 mass% of resin; and 2-10 mass% of an emulsifying agent and 0.5-3 mass% of a leveling agent with respect to 100 mass% of the resin. In addition, when the carbon fiber bundle wound around a bobbin is unwound and measured, the carbon fiber bundle which has the filament number of 12,000 or more to 48,000 or less has fiber width uniformity (CV%) of 11% or lower, a fiber width maintenance rate of 80% or higher, a gap-filling ratio of 0.3 or lower, and the strength conversion ratio (%) of 85% or higher.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a carbon fiber bundle for filament winding,

The present invention relates to a carbon fiber bundle for a filament winding (FW), particularly a carbon fiber bundle having a high strength conversion ratio of a carbon fiber yarn.

Carbon fibers are widely used in aerospace applications, leisure applications, and general industrial applications because of their excellent mechanical properties, in particular, their high specific strength and nonelasticity. Particularly, the filament winding (FW) molding method exhibits a high performance of a composite material and is used for a fuel pressure vessel (bomb) for an aircraft structural member requiring high strength, a natural gas vehicle, a hydrogen fuel cell vehicle, Carbon fiber is formed as a reinforcing fiber by a filament winding forming method, and the demand for carbon fiber suitable for FW molding is increasing day by day.

As the properties of the reinforcing fiber required by the FW molding method, there is a high processability, which is typified by high process operability, resistance to abrasion and fiber breakage, (For example, Japanese Examined Patent Publication Nos. 57-49675, 62-299580, 1-46636, 7-310240, and 8-158163) Etc. have been proposed so far.

Particularly, Japanese Patent Laid-Open Publication No. 7-310240 (Patent No. 3047731) discloses carbon fiber for filament winding molding and a method for producing the same, wherein the strand tensile strength is 400 Kgf / m 2 or more, g / D or more and a strand strength of 100 Kgf / mm < 2 > or more, and an acrylic fiber having a monofilament fineness of 0.8 d or less and a lightness difference (? L) At a temperature of 230 ° C or higher and 280 ° C or lower and at a stretching ratio of 0.80 or more and 1.00 or less and then continuously cooled in an inert atmosphere at a maximum temperature of 1,100 ° C or more and 2,000 ° C or less at a temperature range from 1,000 ° C to a maximum temperature , The carbon fiber is subjected to a surface treatment, a sizing treatment with an epoxy resin or the like, and a method of producing carbon fiber for filament winding molding is described It is.

Japanese Unexamined Patent Application, First Publication No. Hei 8-158163 discloses a carbon fiber bundle and a method for producing the carbon fiber bundle. The carbon fiber bundle and the method for producing the carbon fiber bundle are disclosed in Japanese Patent Application Laid-Open No. 8-158163. The bundle is a substantially unleaded carbon fiber bundle having a yarn split ratio of 40% And a carbon fiber bundle obtained by winding and winding an epoxy resin or the like with a sizing agent, characterized in that the number of filaments of the fiber bundle of the constituent unit is 6,000 or more.

However, these have not been specifically proposed other than to increase the strength of the carbon fiber yarn in order to improve the performance of the pressure vessel. Therefore, there is a problem in that, in the conventional FW forming method, the yarn strength of the carbon fiber is maximally expressed and the characteristics capable of achieving high performance are not sufficiently reflected.

Japanese Patent Publication No. 57-49675 (Announcement of 23 March, 1982) Japanese Unexamined Patent Application No. 62-299580 (published on December 26, 1987) Japanese Patent Office No. 1-46636 (September 10, 1989 announcement) Japanese Patent Application Laid-Open No. 7-310240 (published on November 28, 1995) Japanese Patent Application Laid-Open No. 8-158163 (published on June 18, 1996)

Accordingly, it is an object of the present invention to provide a carbon fiber bundle in which the strength conversion of carbon fiber yarn, that is, the final composite material strength, is improved in filament winding (FW) molding.

Generally, although the strength of the carbon fiber yarn is excellent, if the width of the carbon fiber is not constant during the filament winding forming, or when twist or warping occurs during the running, the volume of the composite material is laminated unevenly, The strength of the composite material is lowered and the strength of the carbon fiber yarn is not maximized.

The present invention is characterized in that, during the filament winding molding, when the carbon fiber is impregnated in the matrix resin, the carbon fiber is not easily deformed. To the carbon fiber.

According to the present invention, it is possible to provide a carbon fiber bundle excellent in moldability and excellent in strength conversion ratio in filament winding (FW) molding. As a result, it is possible to provide a carbon fiber bundle having a high fog ratio the strength conversion ratio of the carbon fiber was improved when the plies ratio (number of plies filled / total plies number) was low, so that a carbon bundle for filament winding capable of producing a high-performance pressure vessel was obtained.

Fig. 1 is a schematic view of a filament winding apparatus according to the present invention, which is a device for evaluating the characteristics of carbon fiber, the strength of a composite material, and the conversion rate of a carbon fiber, and it is determined whether or not a carbon fiber is deformed . (This is because it is difficult to evaluate the warpage and characteristics of composite materials when evaluating the warpage by the carbon fiber itself wound after the sizing agent is applied.)
Fig. 2 is a photograph showing the appearance after the filament winding curing (A) and the appearance after the filament winding specimen ring burst test (B) by carrying out the ring burst strength test after cutting with the ring specimen.

The present invention provides a carbon fiber bundle with improved strength,

An object of the present invention is to provide a carbon fiber bundle for filament winding having a filament winding uniformity (CV%) of 11% or less when the bundle of carbon fiber wound on a bobbin is measured and measured, The ratio of the number of plies of the carbon fiber bundle for the filament winding to the number of plies of the filament winding / total plies number is 0.3 or less (%) Of 85 or more, and the number of filaments of the carbon fiber bundles for filament winding is 12,000 or more and 48,000 or less.

In the filament winding forming process of the present invention, a sizing agent having the following composition is adhered to the carbon fiber so that the carbon fiber is not easily deformed when the carbon fiber is impregnated into the matrix resin. In the sizing agent used in the present invention, , 2 to 10% by mass of an emulsifier and 0.5 to 3% by mass of a smoothing agent. The resin of the sizing agent is characterized by comprising 75 to 90 mass% of an epoxy resin, 5 to 25 mass% of an ester resin, and 3 to 5 mass% of a phenoxy resin.

As the epoxy resin in the resin of the sizing agent, there is a liquid or solid phase type epoxy as a main component, bisphenol A type epoxy (diglycidyl ether of bisphenol A type (DGEBA) Epoxy) Specific examples of the A type epoxy resin (diglycidyl ether bisphenol A type epoxy (DGEBA) Epoxy) include YD-011 (EEW 450 to 500 g / eq.) Of Kukdo Chemical Co., Specific examples of the liquid bisphenol A type epoxy resin include YD-112 (EEW 170-185 g / eq.), YD-128 (EEW 184 to 190 g / eq.).

In the present invention, an ester resin and a phenoxy resin were added in addition to the epoxy resin alone in order to increase the insufficient strength and drape.

The ester resin may be an aliphatic ester compound having no aromatic ring, an aromatic ester compound, a vinyl ester compound, or a mixture of two or more thereof.

When an aromatic ester compound is used, the handling property of the sizing agent-coated carbon fiber is improved. Examples of the unsaturated ester resin include those obtained by dissolving an unsaturated polyester obtained by reacting an acid component containing an?,? - unsaturated dicarboxylic acid with an alcohol in a polymerizable unsaturated monomer. Specific examples of the unsaturated polyester resin include, For example, a condensate of fumaric acid or maleic acid with an adduct of ethylene oxide (abbreviated as EO) of bisphenol A, a condensate of fumaric acid or maleic acid with adduct of propylene oxide (abbreviated as PO) of bisphenol A and fumaric acid Or condensates of maleic acid and bisphenol A with EO and PO adducts. Specific examples of the unsaturated polyester resin include DCPD (registered trademark) of Dow Chemical, Nippon U-Pica U-Pica < (R) >).

Examples of the vinyl ester resin include epoxy (meth) acrylates obtained by esterifying the epoxy compound and an?,? - unsaturated monocarboxylic acid. Examples of the?,? - unsaturated monocarboxylic acid include acrylic acid and methacrylic acid. Specific examples of the vinyl ester resin include bisphenol type epoxy compound (meth) acrylate modified products (epoxy compound of bisphenol A type epoxy compound And a terminal (meth) acrylate-modified resin obtained by reacting a carboxyl group of (meth) acrylic acid, and the like. These modified substances may be dissolved in a monomer such as styrene, if necessary. Specific examples of the vinyl ester resin include DICLITE® of DIC and Vipel® of AOC resin.

The phenoxy resin may be selected from the group consisting of polyoxy (2-hydroxy-1,3-propanediyl) oxy-1,4-phenylene (1-methylidene) -1,3-propanediyl) oxy-1,4-phenylene (1-methylethylidene) -1,4-phenylene), and N, N-diglycidyl 4- (4-methylphenoxy) aniline , N, N-diglycidyl-4- (4-tert-butylphenoxy) aniline and N, N-diglycidyl-4- (4-phenoxy) aniline, Can be obtained by cyclization with an alkali compound. In the present invention, an aqueous dispersion which is easy to handle from the viewpoint of handling is added and used. As a specific example of the phenoxy resin, Hydrosize hp3-02 from Michelman, PKHW-35 from Inchem can be used as a solution dispersed in water.

In the resin composition of the sizing agent, as the epoxy resin component, the solid epoxy resin component is preferably 50 to 100% by mass and is preferably of the emulsion type. If the epoxy resin component ratio is less than 70% by mass, the adhesive strength with the FW matrix resin may be insufficient, and the physical properties of the composite material may be deteriorated. On the other hand, if it exceeds 95% by mass, wettability with the matrix resin is improved, but the morphological stability of the carbon fiber is lowered, and deformation is likely to occur during FW molding, resulting in deterioration of the physical properties of the composite material.

When the amount of the ester resin is 25 mass% or more, compatibility with the matrix resin is lowered and the adhesive strength may be lowered. When the content is less than 3 mass%, the aggregation property and handleability of the carbon fiber may be deteriorated.

 When the water-dispersed phenoxy resin dispersion is not less than 8% by mass based on the total resin, the viscosity becomes too high, and when the carbon fiber sizing agent is adhered, it is lost in rigidity and flexibility, resulting in deterioration of the higher order formability. It does not affect the property of the house.

More preferably, the sizing agent is a composition comprising 80 to 90% by mass of an epoxy resin, 5 to 20% by mass of an ester resin, 3% by mass of a phenoxy resin, 3 to 5% by mass of an emulsifier and 1 to 3% by mass of a smoothing agent.

In the sizing agent of the present invention, an emulsifier is contained in an amount of 2-10 mass%, and if it is a very small amount, a surfactant may be contained, but since it tends to inhibit the adhesion, it is preferably 10 mass% or less. At this time, as the surfactant to be contained, a low molecular weight nonionic surfactant is preferable, and a nonionic surfactant such as a polyoxyethylene alkylphenyl ether, a polyoxyethylene (poly) styrylphenyl ether, a polyoxyethylene (poly) A polyoxyethylene-substituted phenyl ether having a substituted phenyl group, and the like can be appropriately selected. Among these, polyoxyethylene (poly) styrylphenyl ether is preferable. Usually, the surfactant is used to stabilize the sizing agent component in the sizing treatment liquid, but it is preferable that the surfactant is not volatilized in the drying step after the sizing liquid is finally added at the stage of the carbon fiber bundle.

In the case of the smoothing agent of the present invention, it is used to prevent abrasion of the carbon fiber during FW molding. Since it tends to reduce the aggregate property, it is preferable to use a small amount of 3% by mass or less.

In addition, the smoothing agent included can be appropriately selected from polyalkylene ether glycols, esters of aliphatic monohydric alcohols with aliphatic monocarboxylic acids, polyalkylene ether derivatives, and polyoxyalkylene alkyl ethers. Of these, polyalkyl Rhenether glycol is preferred.

The sizing agent is prepared by mixing a solution of a liquid phase epoxy resin, an ester resin, an emulsifier or a smoothing agent and a solid phase phenoxy resin dispersed in water, and then dipping the carbon fiber into a bath containing the liquid sizing agent Passed through a contact roll, dried, and attached with a sizing agent to prepare a bundle of carbon fiber for filament winding.

The sizing agent adhesion amount is preferably in the range of 0.1 to 10 parts by mass, more preferably 0.2 to 2 parts by mass with respect to 100 parts by mass of the carbon fiber. When the adhesion amount of the sizing agent is 0.1 parts by mass or more, the carbon fiber can withstand the friction by the metal guide or the like when filament winding, and the occurrence of fluff is suppressed, and the quality of the carbon fiber sheet is excellent such as smoothness. On the other hand, when the adhesion amount of the sizing agent is 10 parts by mass or less, a matrix resin such as epoxy resin is impregnated into the carbon fiber bundle without being inhibited by the sizing film around the bundles of carbon fibers, The composite material is excellent in durability and mechanical properties at the same time.

The viscosity of the sizing agents of the present invention is that the viscosity at 80 ℃ based on solids after removal of the water 4ⅹ10 ⁴ ~ 8ⅹ10 ⁵ cP, preferably in the 6ⅹ10 ⁴ ~ 4ⅹ10 ⁵ cP. If the viscosity of the solid content of more than 1ⅹ10 ⁶ cP sizing is, FW molded a friction force of the FW molding process increases the time of manufacture to the scratch and last poor, easy to all occurs, the viscosity is less than 1ⅹ10 ⁴ cP , There is a lack of the aggregate property of the fibers, and a gap is formed during the FW molding, resulting in a decrease in the strength of the composite material.

The degree of deformation of the carbon fiber was measured by measuring the sagittal width before and after impregnation with the matrix resin, calculating the variation ratio, and expressing the sagittal retention ratio (= width x 100 / width after resin impregnation after resin impregnation).

The plastic softening resin composition using the carbon fiber bundle according to the present invention and the molded article obtained by molding the resin composition are also within the protection scope of the present invention.

Examples of the present invention and comparative examples will be described below.

Example

The sizing agent was prepared by mixing a liquid phenolic resin, an ester resin, an emulsifier and a smoothing agent with a solid phenoxy resin on a water basis in accordance with the composition and amount (mass%) of the Comparative Examples and Examples described in Table 1 below . The carbon fibers were dipped in a bath containing the liquid sizing agent, passed through a contact roll, dried, and then attached with a sizing agent to prepare a carbon fiber bundle for filament wind.

The viscosity (cP, 80 캜) of the sizing agent during the course of the reactions of the comparative examples and the examples was measured and described in Table 1 together.

The sizing agent is applied to the carbon fiber bundle in a liquid state in which the resin component, the emulsifier and the smoothing agent are emulsified. The viscosity of the sizing agent is adjusted by using a rheometer (Anton Paar MCR-301) After removing excess water and solvent from the treatment liquid (emulsion), the shear rate was measured at a rate of 5 占 폚 / min.

Table 1. Sizing composition and viscosity of carbon fiber

Sizing agent (main component)
Emulsifier

Smoothing agent
Viscosity
(cPat 80 ° C) CF strand
Strength (GPa)
Epoxy ester Phenoxy Comparative Example 1 95 5 - 5 2 1.2 x 10 ⁴ 5.70 Example 1 90 5 5 5 3 8.5 × 10 ⁴ 5.40 Example 2 85 10 5 5 3 1.3 x 10 ⁵ 5.73 Example 3 83 14 3 4 2 6.9 × 10 ⁵ 6.05 Example 4 80 16 4 3 One 3.8 × 10 ⁵ 6.18

Experimental Example

(CV%), a haze maintenance ratio (%), a haze holding ratio uniformity (CV%), and a frying rate (%) in a hoop direction with respect to a tow of a carbon fiber bundle produced according to the above Comparative Examples and Examples And the intensity conversion rate (%) was calculated by evaluating the ring burst strength. The ILSS (MPa) was measured and the results are shown in Table 2 below.

Table 2. Filament winding process evaluation and ring burst strength evaluation with attached carbon fiber (Same for all SPUs at 1.0%)

Haze Haze
CV% (%)
( Resin impregnated after-warp width x 100 resin impregnated transfer width) Uniformity ratio
(CV%) Crevice plies
Whole plies Strength Conversion Rate (%)
( Ring burst strength × 100 CF strand strength) ILSS
(MPa) Comparative Example 1 7.2 10.1 78.0 12.5% 0.80 80.4 79.8 Example 1 7.3 9.2 88.0 11.0% 0.30 87.5 85.4 Example 2 6.5 6.8 93.0 5.7% 0.30 89.2 87.4 Example 3 5.5 5.1 93.0 4.6% 0.28 90.8 89.5 Example 4 6.3 4.5 95.0 3.5% 0.25 93.7 91.2

* Total plies: the number of laminations (number of winding) to produce the filament winding specimen

* Gap fill plies: the number of laminations at which filaments are wound,

* ILSS (interlaminar shear strength)

(Measured according to ASTM D2344)

According to the present invention, the strength conversion ratio of the carbon fiber is improved,

A carbon bundle for filament winding that can be manufactured was obtained.

Claims (15)

A carbon fiber bundle attached to a carbon fiber surface with a sizing agent, and a bundle of carbon fiber bundles for a filament winding having a filament winding uniformity (CV%) of 11% or less when the bundle of carbon fibers wound on a bobbin is measured. The carbon fiber bundle according to claim 1, wherein the filament retention ratio of the carbon fiber bundle for filament winding (filament width after resin impregnation x 100 / resin impregnated filament width) is 80% or more. The carbon fiber bundle according to claim 1, wherein the ratio of void filling plies / total plies of the carbon fiber bundle for filament winding is 0.3 or less and the strength conversion ratio (%) is 85 or more. The carbon fiber bundle according to claim 1, wherein the number of filaments of the carbon fiber bundles for filament winding is 12,000 or more and 48,000 or less. 3 to 5 mass% of a solid phenoxy resin is added to the water phase in which 75 to 90 mass% of liquid epoxy resin, 5 to 25 mass% of ester resin, 2 to 10 mass% of emulsifier and 0.5 to 3 mass% of smoothing agent are mixed, To obtain a sizing agent in a liquid phase, then dipping and passing carbon fibers into a bath, passing through a contact roll, and drying to attach a sizing agent. 6. The epoxy resin composition according to claim 5, wherein the epoxy resin is a diglycidyl ether bisphenol A type epoxy resin; The ester resin may be a condensate of fumaric acid or maleic acid with an ethylene oxide adduct of bisphenol A, a condensate of fumaric acid or maleic acid with a propylene oxide adduct of bisphenol A, ethylene oxide of propylene oxide or maleic acid and bisphenol A, An unsaturated polyester resin or bisphenol A-type epoxy compound (meth) acrylate modified product selected from condensates with a seed adduct; Characterized in that the phenoxy resin is polyoxy (2-hydroxy-1,3-propanediyl) oxy-1,4-phenylene (1-methylidene) A method for producing a fiber bundle. The method according to claim 5, wherein the emulsifier is a surfactant selected from the group consisting of polyoxyethylene alkyl phenyl ether, polyoxyethylene (poly) styryl phenyl ether, and polyoxyethylene (poly) benzyl phenyl ether. The method for producing a carbon fiber bundle according to claim 7, wherein the surfactant is polyoxyethylene (poly) styryl phenyl ether. The method according to claim 5, wherein the smoothing agent is selected from the group consisting of a polyalkylene ether glycol, an ester of an aliphatic monohydric alcohol with an aliphatic monocarboxylic acid and a polyalkylene ether derivative, and a polyoxyalkylene alkyl ether group. The method for producing a carbon fiber bundle according to claim 9, wherein the smoothing agent is a polyalkylene ether glycol. The method for producing a carbon fiber bundle according to claim 5, wherein the sizing agent has a viscosity of ⁴ x ¹⁰ < ⁴ > to 8 x ¹⁰ < ⁵ > cP at 80 DEG C based on the solid content after removal of water The method for producing a carbon fiber bundle according to claim 11, wherein the viscosity of the sizing agent is 6 x 10 ⁴ to ⁴ x 10 ⁵ cP. 6. The carbon fiber bundle according to claim 5, wherein the carbon fiber bundle wound on the bobbin of the obtained carbon fiber bundle is subjected to measurement to have a haze uniformity (CV%) of 11% or less and a haze retentivity (haze width after resin impregnation x 100 / Wherein the carbon fiber bundle has a physical property of 80% or more, a void filling plies / total plies ratio of 0.3 or less, an intensity conversion ratio (%) of 85 or more, and a filament count of 12,000 or more to 48,000 or less. A thermosetting resin composition comprising the carbon fiber bundle of any one of claims 1 to 4. A molded article obtained by molding the resin composition of claim 14.

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