KR102150732B1 - A carbon-fiber for filament winding bundle - Google Patents

Abstract

With respect to 100% by mass of the resin, 2 to 10% by mass of an emulsifier and 0.5% by mass of a leveling agent for 100% by mass of the resin containing 75 to 90% by mass of the epoxy resin, 5 to 25% by mass of the ester resin, and 3 to 5% by mass of the phenoxy resin. It relates to a carbon fiber sizing agent containing 3% by mass and a carbon fiber bundle in which the sizing agent is attached to the surface of carbon fibers, and the yarn width uniformity (CV%) is 11% or less when measured by spinning a carbon fiber bundle wound around a bobbin. And, the yarn width retention rate is 80% or more, the gap filling ratio is 0.3 or less, and the strength conversion rate (%) is 85 or more, and the number of filaments is 12,000 or more to 48,000 or less.

Description

Carbon fiber bundle for filament winding {A CARBON-FIBER FOR FILAMENT WINDING BUNDLE}

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

Carbon fiber is widely used in aerospace, leisure, and general industrial applications because of its excellent mechanical properties, especially specific strength and high inelastic modulus. In particular, the filament winding (FW) molding method is used for fuel pressure vessels (cylinders) such as aircraft structural materials, natural gas vehicles, hydrogen fuel cell vehicles, etc., which require high strength due to the high performance of composite materials. In order to increase the performance and performance, carbon fibers are molded as reinforcing fibers by a filament winding molding method, and the demand for carbon fibers suitable for FW molding is increasing day by day.

As a characteristic of the reinforcing fiber required by the FW molding method, there is a high process passability, such as high process operability, abrasion resistance, and fiber breakage, which are typical of fluff resistance, and a sizing agent for carbon fiber as a method to improve such performance. (For example, Japanese Patent Publication No. 57-49675, Japanese Patent Publication No. 62-299580, Japanese Patent Publication No. Hei 1-46636, Japanese Patent Publication No. Hei 7-310240, and Japanese Patent Publication No. 8-158163) Etc. have been proposed so far.

Among them, Japanese Unexamined Patent Application Publication No. 7-310240 (Patent No. 3047731) introduces a carbon fiber for filament winding molding and its manufacturing method. The strand tensile strength is 400 Kgf/㎡ or more, and the thread breakage limit tension is 0.2. Carbonic acid fiber for filament winding molding, characterized in that g/D or more and strand strength is 100 Kgf/mm 2 or more, and acrylic fiber having a single fiber fineness of 0.8 d or less and a lightness difference (ΔL) of 50 or less by the urea bonding method As a raw material, it is flame-resistant in air with a temperature of 230 ℃ or more and 280 ℃ or less, and a draw ratio of 0.80 or more and 1.00 or less, and then in an inert atmosphere with a maximum temperature of 1,100 ℃ or more and 2,000 ℃ or less, from 1,000 ℃ to the maximum temperature. In this regard, a method for producing a carbon fiber for filament winding molding, characterized in that the draw ratio is 0.98 or less, is carbonized, and then subjected to surface treatment and sizing with an epoxy resin, has been introduced.

In addition, Japanese Patent Application Laid-Open No. 8-158163 introduces a bundle of carbon fibers and a method for manufacturing the same, which is a bundle of substantially lead-free carbon fibers having a yarn splitting rate of 40% or less, and the bundle is a bobbin or cheese bundle. A carbon fiber bundle, characterized by being wound around a carbon fiber bundle, and a carbon fiber bundle wound with an epoxy resin or the like as a sizing agent, characterized in that the number of filaments in the fiber bundle of a constituent unit is 6,000 or more are introduced.

However, these are characteristics for improving the performance of the pressure vessel, and there is no particular proposal other than the high strength of the carbon fiber yarn. Therefore, in the conventional FW molding method, there is a problem in that the characteristics of the carbon fiber yarn strength to be maximized and high performance are not sufficiently reflected.

Japanese special agency 57-49675 (announcement on October 23, 1982) Japanese special agency No. 62-299580 (published on December 26, 1987) Japanese Special Publication No. 1-46636 (announcement on October 9, 1989) Japanese Patent Publication No. 7-310240 (published on November 28, 1995) Japanese Patent Publication No. 8-158163 (published on June 18, 1996)

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

In general, even though the carbon fiber yarn has excellent strength, if the yarn width of the carbon fiber is not constant during filament winding molding, or when yarn twisting or twisting occurs during driving, the volume of the composite material is not uniformly stacked. In this case, defects such as gaps or voids are generated, resulting in a decrease in the strength of the composite material, and a problem in that the strength of the carbon fiber yarn is not expressed to the maximum.

In the present invention, during filament winding molding, when the carbon fiber is impregnated with a matrix resin, it is characterized in that the carbon fiber has a property that it is not easy to deform, and this property is a sizing agent having the following composition of the present invention. Was solved by attaching to the carbon fiber.

According to the present invention, in filament winding (FW) molding, it was possible to provide a bundle of carbon fibers with excellent formability and excellent strength conversion rate.The ratio of ply filled with high yarn width during the FW process was high. When the (plies ratio; number of plies filled in the gap/number of total plies) was low, the strength conversion rate of carbon fiber was improved, and thus a carbon bundle for filament winding was obtained that enables the manufacture of high-performance pressure vessels.

1 is a schematic diagram of a filament winding device of the present invention, which is a device for evaluating the properties of carbon fiber, strength of a composite material, and conversion rate of carbon fiber strength, and determining whether the carbon fiber is deformed (thread width retention rate) after applying a sizing agent. It is to do. (This is because it is difficult to determine the yarn width or characteristics when manufacturing composite materials by evaluating the yarn width with the wound carbon fiber itself after the sizing agent is applied.)
Figure 2 is a product of Example 4, after cutting into a ring specimen and performing a ring burst strength test, and shows a picture after the filament winding hardening (A) and the filament winding specimen after the ring burst test (B).

The present invention is to provide a carbon fiber bundle with improved strength,

It is an object of the present invention to provide a bundle of carbon fibers for filament winding having a yarn width uniformity (CV%) of 11% or less when measured by spinning a bundle of carbon fibers wound around a bobbin, and for the filament winding The yarn width retention rate of the carbon fiber bundle (the yarn width after resin impregnation × 100/the yarn width before resin impregnation) is 80% or more, and the ratio of the number of plies/total plies to the number of plies for filament winding is 0.3 or less. It is to provide a carbon fiber bundle, characterized in that the strength conversion rate (%) is 85 or more, and the number of filaments of the carbon fiber bundle for filament winding is 12,000 or more and 48,000 or less.

During the filament winding molding of the present invention, when the carbon fiber is impregnated with the matrix resin, a sizing agent having the following composition is attached to the carbon fiber so that the carbon fiber is not easily deformed, and the sizing agent used in the present invention is 100% by mass of the resin. About 2 to 10 mass% of emulsifier and 0.5 to 3 mass% of leveling agent are contained. The resin of the sizing agent is characterized by consisting of 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.

Among the resins of the sizing agent, there are two types of epoxy resins, such as bisphenol A type epoxy (Diglycidyl ether of bisphenol A type (DGEBA) Epoxy) as a main component, and liquid and solid type epoxy. A specific example of the type A epoxy resin (diglycidyl ether of bisphenol A type (DGEBA) Epoxy) is YD-011 (EEW 450-500 g/eq. ), YD-014 (EEW 900-1000 g/eq.), and specific examples of the liquid bisphenol A epoxy resin include YD-112 (EEW 170-185 g/eq.), YD-128 (EEW 184-190 g/eq.) etc. are mentioned.

In the present invention, an ester resin and a phenoxy resin were added and added in order to increase binding and drape, which is insufficient with only the epoxy resin.

The ester resin may be an aliphatic ester compound that does not have an aromatic ring, may be an aromatic ester compound, may be a vinyl ester compound, or may be used in combination of two or more.

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

As a vinyl ester resin, an epoxy (meth)acrylate obtained by esterifying the said epoxy compound and an α,β-unsaturated monocarboxylic acid can be mentioned. Examples of the α,β-unsaturated monocarboxylic acid include acrylic acid, methacrylic acid, and the like. As a specific example of the vinyl ester resin, for example, a bisphenol type epoxy compound (meth)acrylate modified product (the epoxy group of the bisphenol A type epoxy compound And terminal (meth)acrylate-modified resins obtained by reacting with the carboxyl group of (meth)acrylic acid), and the like, and these modified products may be dissolved in a monomer such as styrene, if necessary. Specific examples of the vinyl ester resin include DICLITE ® from DIC, Vipel ® from AOC resin, and the like.

Phenoxy resin is polyoxy (2-hydroxy-1,3-propanyldiyl) oxy-1,4-phenylene (1-methyldiene) -1,4-phenylene) (Polyoxy (2-hydroxy It is a compound called -1,3-propanediyl)oxy-1,4-phenylene(1-methylethylidene)-1,4-phenylene), which is N,N-diglycidyl-4-(4-methylphenoxy)aniline. , Epichlorohydrin was added to N,N-diglycidyl-4-(4-tert-butylphenoxy)aniline and N,N-diglycidyl-4-(4-phenoxy)aniline, It can be obtained by cyclization with an alkali compound. In the present invention, it was added and used as an easy-to-handle aqueous dispersion in terms of handling properties. As a specific example of the phenoxy resin, among them, Michelman's Hydrosize hp3-02, Inchem's PKHW-35, and the like can be used as a solution dispersed in water.

Of the resin composition of the sizing agent, the epoxy resin component is preferably an emulsion type with a solid epoxy resin component of 50 to 100% by mass. 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 composite material properties may be deteriorated. In addition, when it exceeds 95% by mass, the wettability with the matrix resin is improved, but the morphological stability of the carbon fiber is lowered, and deformation tends to occur during FW molding, and the composite material properties are deteriorated.

When the amount of the ester resin is 25% by mass or more, compatibility with the matrix resin may be lowered, resulting in a decrease in adhesive strength, and when the amount is 3% by mass or less, the binding properties and handling properties of the carbon fibers may decrease.

If the water-dispersed phenoxy resin dispersion is more than 8% by mass with respect to the total resin, the viscosity becomes too high, and when the carbon fiber sizing agent is attached, it loses its rigidity and flexibility, resulting in a problem of deteriorating high-order processability. If it does, it does not affect the focus.

A more preferable sizing agent is a composition in the range of 80 to 90% by mass of an epoxy resin, 5 to 20% by mass of an ester resin, 3% by weight of a phenoxy resin, 3 to 5% by mass of an emulsifier, and 1 to 3% by mass of a leveling agent.

In the sizing agent of the present invention, the emulsifier is composed of 2-10% by mass, and a surfactant may be included in a small amount, but a small amount of 10% by mass or less is preferable because it tends to impair adhesion. At this time, as the surfactant to be included, a low molecular weight nonionic surfactant is preferable, and a hydrocarbon group such as polyoxyethylene alkyl phenyl ether, polyoxyethylene (poly) styryl phenyl ether, and polyoxyethylene (poly) benzyl phenyl ether is used. Polyoxyethylene substituted phenyl ethers having a substituted phenyl group and the like can be appropriately selected. Among these, polyoxyethylene (poly) styryl phenyl ether is preferred. 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 present in the final stage of the carbon fiber bundle by volatilization in the drying step after the sizing liquid is applied.

In the case of the leveling agent of the present invention, it is used to prevent abrasion of carbon fibers during FW molding, but it is preferable to use a small amount of 3% by mass or less because it tends to reduce the binding property.

In addition, the leveling agent to be included can be appropriately selected from polyalkylene ether glycol, esters of aliphatic monohydric alcohols and aliphatic monocarboxylic acids or polyalkylene ether derivatives, polyoxyalkylene alkyl ethers, and the like. Rene ether glycol is preferred.

The sizing agent is prepared by mixing a liquid epoxy resin, ester resin and a solution in which a solid phenoxy resin is dispersed in water in a water phase with an emulsifier or leveling agent, and then dipping carbon fibers in a bath containing such a liquid sizing agent. After passing through, passing through a contact roll, drying, and attaching a sizing agent to prepare a carbon fiber bundle for filament winding.

The amount of sizing agent adhered is preferably in the range of 0.1 to 10 parts by mass, more preferably 0.2 to 2 parts by mass per 100 parts by mass of the carbon fiber. When the amount of the sizing agent adhered is 0.1 parts by mass or more, the carbon fiber can withstand friction by a metal guide or the like when the filament is wound, and fluff is suppressed, so that the smoothness of the carbon fiber sheet is excellent. On the other hand, when the adhesion amount of the sizing agent is 10 parts by mass or less, the sizing film formation around the carbon fiber bundle is not impaired, and a matrix resin such as an epoxy resin is impregnated into the carbon fiber bundle, and void formation in the resulting composite material is suppressed, The quality of the composite material is excellent, and at the same time, the mechanical properties are excellent.

The viscosity of the sizing agent 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. When the viscosity of the solid content of the sizing agent exceeds 1×10 ⁶ cP, the friction force in the FW molding process increases at the time of manufacturing the FW molded product, resulting in poor abrasion resistance, all easily occurring, and the viscosity is less than 1×10 ⁴ cP. In this case, due to insufficient fiber binding, a gap is generated during FW molding, resulting in a decrease in the strength of the composite material.

The degree of deformation of the carbon fiber was expressed by measuring the yarn width before and after impregnating the matrix resin and calculating the variation rate, and the yarn width retention rate (= yarn width after resin impregnation x100 / yarn width before resin impregnation).

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

Hereinafter, an experimental example will be described along with the examples and comparative examples of the present invention.

Example

The sizing agent contains a liquid epoxy resin, an ester resin, an emulsifier, and a leveling agent in a water-phase solid phenoxy resin according to the composition components and usage (% by mass) of Comparative Examples and Examples as shown in Table 1 below. It was prepared by dissolving. Carbon fiber was dipped in the bath containing the liquid sizing agent, passed through it, passed through a contact roll, dried, and then a sizing agent was attached to prepare a carbon fiber bundle for filament winding.

The viscosity (cP, 80° C.) of the sizing agent during the reaction of Comparative Examples and Examples was measured and described together in Table 1.

The sizing agent is given to the carbon fiber bundle in a liquid state in which a resin component, an emulsifier, and a leveling agent are emulsified, and the viscosity of the sizing agent is removed by drying water in the liquid state, using a rheometer (Anton Paar's MCR-301). Then, excess moisture or solvent was removed from the treatment liquid (emulsion), and then the shear rate was measured at 5°C/min.

Table 1. Composition and viscosity of sizing agent attached to carbon fiber

Sizing agent resin (main component)
Emulsifier

Leveling agent
Viscosity
(cPat80℃) CF strand
Strength (GPa)
Epoxy ester Phenoxy Comparative Example 1 95 5 - 5 2 1.2×10 ⁴ 5.70 Example 1 90 5 5 5 3 8.5×10 ⁴ 5.40 Example 2 85 10 5 5 3 1.3×10 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

The yarn width (CV%), yarn width retention rate (%), yarn width retention rate uniformity (CV%), fly when filament winding in the hoop direction with respect to the carbon fiber bundle 1 tow prepared according to the Comparative Examples and Examples The ratio was measured, the strength conversion rate (%) was calculated through the ring burst strength evaluation, and 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 carbon fiber with sizing agent attached (however, all SPUs are equal to 1.0%)

Sapok Sapok
CV% Death width maintenance rate (%)
( Width after resin impregnation × 100 width after resin impregnation) Uniformity of death width maintenance rate
(CV%) Crevice plies
Full 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: Number of stacks (number of windings) to prepare filament winding specimens

*Gap filling plies: The number of stacks that the gap disappears when winding the filament (winding number)

*ILSS (Interlaminate shear strength)

(Measured based on measurement standard ASTM D2344)

According to the present invention, the strength conversion rate of carbon fiber is improved, and a high-performance pressure vessel

A fabricable filament winding carbon bundle could be obtained.

Claims (15)

A carbon fiber bundle with a sizing agent attached to the surface of the carbon fiber, when measured by spinning the carbon fiber bundle wound around a bobbin, the yarn width uniformity (CV%) is 11% or less, and the yarn width retention rate (thread width after resin impregnation × 100/resin) A bundle of carbon fibers for filament winding with a settling yarn width of 80% or more.

delete The method according to claim 1, wherein the number of gap-filled plies/number of total plies of the filament winding carbon fiber bundle is 0.3 or less, and the strength conversion rate (%) is 85 or more, wherein, the total number of plies is filament winding. It means the number of stacks (winding number) for manufacturing the specimen, and the number of plies filled with gaps means the number of stacks (winding number) at which the gap disappears during filament winding. The carbon fiber bundle according to claim 1, wherein the number of filaments in the carbon fiber bundle for filament winding is 12,000 or more to 48,000 or less. 3 to 5 mass% of a solid phenoxy resin in a water phase in which 75 to 90 mass% of a liquid epoxy resin, 5 to 25 mass% of an ester resin, 2 to 10 mass% of an emulsifier, and 0.5 to 3 mass% of a leveling agent are mixed To obtain a liquid sizing agent, and then dip the carbon fiber through the bathtub, pass it through a contact roll, dry it, and attach the sizing agent. CV%) is 11% or less, and the yarn width retention rate (the yarn width after resin impregnation × 100/the yarn width before resin impregnation) is 80% or more. The method according to claim 5, wherein the epoxy resin is a diglycidyl ether bisphenol A type epoxy resin; Ester resins are fumaric acid or a condensate of maleic acid and an ethylene oxide adduct of bisphenol A, fumaric acid or a condensation product of maleic acid and a propylene oxide adduct of bisphenol A, fumaric acid or maleic acid and bisphenol A ethylene oxide and propylene oxide One type of unsaturated polyester resin or bisphenol A epoxy compound (meth)acrylate modified product selected from condensation products with seed adducts; The phenoxy resin is a carbon, characterized in that polyoxy (2-hydroxy-1,3-propanyldiyl) oxy-1,4-phenylene (1-methyldiene)-1,4-phenylene) Method for producing a fiber bundle. The method of claim 5, wherein the emulsifier is a surfactant, polyoxyethylene alkyl phenyl ether, polyoxyethylene (poly) styryl phenyl ether, or polyoxyethylene (poly) benzyl phenyl ether. The method of claim 7, wherein the surfactant is polyoxyethylene (poly) styryl phenyl ether. The method of claim 5, wherein the leveling agent is a polyalkylene ether glycol, an ester of an aliphatic monohydric alcohol and an aliphatic monocarboxylic acid or a polyalkylene ether derivative, and a polyoxyalkylene alkyl ether group. The method of claim 9, wherein the leveling agent is a polyalkylene ether glycol. The method for producing a carbon fiber bundle according to claim 5, wherein the viscosity of the sizing agent is 4x10 ⁴ ~ 8x10 ⁵ cP at 80 °C based on the solid content after water is removed. The method of claim 11, wherein the sizing agent has a viscosity of 6x10 ⁴ to 4x10 ⁵ cP. The method according to claim 5, wherein when the carbon fiber bundle wound in the bobbin shape of the obtained carbon fiber bundle is seamed and measured, the yarn width uniformity (CV%) is 11% or less, and the yarn width retention rate (the yarn width after resin impregnation x100/the yarn width before resin impregnation) is 80. % Or more, and the ratio of the number of plies filled/total plies is 0.3 or less, the strength conversion ratio (%) is 85 or more, and the number of filaments is 12,000 or more to 48,000 or less.In the above, the total number of plies is filament winding A method of manufacturing a carbon fiber bundle, which means the number of stacks (winding number) for manufacturing a specimen, and the number of gap-filled plies means the number of layers (winding number) at which the gap disappears during filament winding. A thermosetting resin composition comprising the carbon fiber bundle according to any one of claims 1, 3, and 4. A molded article obtained by molding the thermosetting resin composition of claim 14.

Images