JPH10131052A - Sized carbon fiber strand and prepreg using the carbon fiber as reinforced fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the opening property and abrasion resistance of carbon fiber strand and impregnation ability of a resin on the production of prepreg by sizing with a sizing agent containing a polyester resin and a polyether resin as essential components. SOLUTION: A sizing agent containing (A) a polyester resin (preferably, polyethylene terephthalate) and (B) a polyester resin of the formula R1 O(CH2 CH2 O)m R2 [R1 is a 1-30C alkyl, bisphenol A or phenyl; R2 is H or glycidyl: (m) is an integer of 1-66] [e.g. polyoxyethylene (m) lauryl glycidyl ether] as essential components at a weight ratio of (60-90):(40-10).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber strand having excellent spreadability and abrasion resistance, and a prepreg using the carbon fiber strand as a reinforcing fiber. More specifically, the present invention relates to a carbon fiber strand which generates less fluff due to abrasion in a prepreg manufacturing process, is excellent in handleability, and is excellent in fiber opening during resin impregnation, and a prepreg using the carbon fiber strand as a reinforcing fiber. .

[0002]

2. Description of the Related Art Carbon fiber has been widely used in leisure and sports fields as a composite material using various resin compositions as a matrix, taking advantage of its excellent characteristics. I have.

[0003] The carbon fiber is impregnated with a resin composition in a state where the carbon fiber is generally aligned in one direction as a strand (a fiber bundle composed of thousands to tens of thousands of filaments), and is unidirectionally oriented prepreg ( (UD so-called prepreg) or impregnated with a resin composition in a woven state, and formed into a woven prepreg in the next step, and is often used as a composite material. In these processing steps,
Since carbon fiber strands are liable to fluff due to rubbing with a guide or the like, and handling properties are deteriorated, usually, the surface of the carbon fiber strands is coated with a sizing agent to enhance the convergence of the fibers, to improve the abrasion resistance and handling. The processing for improving the performance is performed.

[0004] Regarding this sizing agent, since most of the matrix resin used for the composite material is an epoxy resin,
A sizing agent based on an epoxy resin represented by bisphenol A glycidyl ether type epoxy resin has been proposed. For example, Japanese Patent Application Laid-Open No. 7-197381 discloses that a bisphenol A type epoxy resin (component A) which is liquid at room temperature, a bisphenol A type epoxy resin which is solid at room temperature (component B), and an unsaturated polyester resin (component C) are applied to carbon fiber strands. A sizing agent for carbon fiber strands containing stearic acid (D component) as an essential component has been proposed. The carbon fiber strand treated with the sizing agent described in the publication has good abrasion resistance, and the prepreg produced from the carbon fiber strand has good surface smoothness, and the adhesion between the prepregs is improved. It has been shown to be excellent. However, in order to use a prepreg to form a molded article having more excellent durability, there is a demand for a prepreg capable of imparting a higher interlayer shear strength or a carbon fiber strand as a material thereof. Furthermore, intermediates of liquid epoxy resin are designated as carcinogenic substances by the Ministry of Labor Safety Standards Bureau (new mutagenic substance No. 2
12-2) Therefore, a non-epoxy resin sizing agent has been demanded in consideration of the effect on the human body during handling. It is desired that the sizing agent is in the form of an aqueous solution or an aqueous dispersion from the viewpoint of a safe environment.

[0005] Non-epoxy resin sizing agents include, for example, JP-A-62-299573 and JP-A-63-92.
No. 780 discloses a sizing agent using a polyester resin as a carbon fiber suitable for a matrix such as an unsaturated polyester or vinyl ester. However, according to the experiment of the inventor, although the carbon fiber strand sized with the sizing agent described above has an effect of suppressing fluff and yarn breakage, the fiber opening property is reduced, and the matrix resin is sufficient for the carbon fiber strand. Has a problem that it is not impregnated.

[0006] As a sizing agent having excellent opening properties, Japanese Patent Application Laid-Open No. 60-246872 discloses a sizing agent using a polyether resin. However,
According to the experiment of the inventor, carbon fiber strands sized with the sizing agent described in JP-A-60-246872 have good spreadability but have reduced abrasion resistance, and fluff is generated on the carbon fiber strands. There's a problem. Further, a sizing agent using the same polyether resin is disclosed in
No. 57974 is disclosed, but there is a problem that the sizing agent can be used only in a solution dissolved in N-methylpyrrolidone.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention eliminates the drawbacks of the above-mentioned prior art, and provides both excellent carbon fiber strand openability and abrasion resistance during prepreg production and resin impregnation into carbon fiber strands. It is an object of the present invention to provide a carbon fiber strand which improves the above, and a prepreg using the carbon fiber strand as a reinforcing fiber. It is another object of the present invention to reduce the effect on the human body when handling the sizing agent.

[0008]

In order to solve the above problems, the carbon fiber strand of the present invention is characterized in that it is sized with a sizing agent containing polyester resin and polyether resin as essential components. The polyester resin used in the present invention is characterized by being represented by the following chemical formula (1), and the polyether resin is represented by the following chemical formula (1).

[0009]

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(Wherein R 1 represents an alkyl group having 1 to 30 carbon atoms, bisphenol A or phenyl group, R 2 represents hydrogen or glycidyl group, and m represents an integer of 1 to 60). The amount of the polyester resin and the polyether resin is 60 to
It is characterized by 90% by weight and 10-40% by weight of polyether resin. Further, in the carbon fiber strand of the present invention, the sizing agent contains 5 to 2 higher fatty acid esters.
It is characterized by containing 0% by weight.

By adopting the above constitution, the present invention solves the problems of the conventional sizing agent, and since the carbon fiber strands are excellent in opening property during prepreg production, the surface smoothness and impregnation of the prepreg are good. Moreover, since the carbon fiber strands are excellent in abrasion resistance, there is no generation of fluff or yarn breakage due to contact with a roller or a guide, and a carbon fiber strand having excellent handling properties can be obtained.

Hereinafter, the present invention will be described in detail. For the carbon fiber strand to which the carbon fiber strand of the present invention is applied, a fiber bundle in which thousands to tens of thousands of well-known carbon fiber filaments such as acrylonitrile, rayon, and pitch are bundled is preferably used. The fibers also include graphite fibers.

In the present invention, the polyester resin used as a sizing agent is formed by a polycondensate of a polybasic acid and a polyhydric alcohol. Polybasic acids include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, sebacic acid, tetrahydrophthalic acid, hexahydrophthalic acid, tetrachlorophthalic acid,
And succinic acid and acid anhydrides thereof. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, butane-1,3-diol, butane-1,4-diol and higher homologues thereof, and dihydric alcohols such as neopentyl glycol and polyethylene glycol. Examples thereof include alcohols, trihydric or higher alcohols such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

The polyester resin used in the present invention comprises:
What is necessary is just what was produced by the above-mentioned polycondensation product of the polybasic acid and the polyhydric alcohol. In particular, polyethylene terephthalate obtained by the polycondensation reaction of terephthalic acid and ethylene glycol can be suitably used. Such polyester resins include Nichigo Polyester XWR9
30, XWR950, XWR901, XWR961 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), Eastman WD, WL
P (manufactured by Eastman Kodak Company) and the like.

In the present invention, the polyether resin used as a sizing agent is represented by the following chemical formula.

[0016]

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(In the formula, R1 represents an alkyl group having 1 to 30 carbon atoms, bisphenol A or phenyl group, R2 represents hydrogen or glycidyl group, and m represents an integer of 1 to 60). Ethylene (m) lauryl glycidyl ether, polyoxyethylene (m) lauryl ether, ethylene oxide (m) adduct of bisphenol A, polyoxyethylene (m) phenyl glycidyl ether, polyoxyethylene (m) phenyl ether, and the like. .

In the present invention, the combination of the polyester resin and the polyether resin described above is not limited, but the polyester resin is polyethylene terephthalate, and the polyether resin is polyoxyethylene (m) lauryl glycidyl ether, or ethylene oxide of bisphenol A ( m) Combinations of adducts are particularly preferred.

In the present invention, when the total amount of the polyester resin and the polyether resin used as the sizing agent is 100% by weight, the polyester resin is 60 to 90% by weight and the polyether resin is 10 to 10% by weight.
The range is 40% by weight. If the blending amount of the polyester resin is less than 60% by weight, the scratch resistance is reduced, and fluff is generated. If the blending amount of the polyester resin exceeds 90% by weight, the spreadability is deteriorated, and the impregnation of the carbon fiber strand with the matrix resin is reduced.

The sizing agent used in the present invention is a resin composition in which a polyester resin and a polyether resin are mixed as essential components, but may contain a higher fatty acid ester as a third component. Specific examples include methyl stearate, ethyl stearate, propyl stearate, butyl stearate, octyl stearate, stearic acid esters such as stearyl stearate, and oleic acid esters such as isopropyl palmitate.

In the present invention, the blending amount of the higher fatty acid as the third component is in the range of 5 to 20% by weight when the whole sizing agent is 100% by weight. When the blending amount of the higher fatty acid exceeds 20% by weight, the composite physical properties of the molded article are deteriorated.

The carbon fiber strand of the present invention has a sizing agent adhering amount to the carbon fiber strand of 0.1 to 0.1%.
3.0% by weight, preferably 0.2 to 1.0% by weight
It is. If the amount of the sizing agent is less than 0.1% by weight, good scratch resistance cannot be obtained. If the amount of the sizing agent is more than 3.0% by weight, the carbon fiber strand becomes firm and the fiber-opening property is reduced, so that the impregnating property of the carbon fiber strand with the matrix resin is reduced.

In the present invention, as a method for adhering a sizing agent to the carbon fiber strand, a commonly used dipping method, roller transfer method, spray method and the like are applied. The amount of the sizing agent attached to the carbon fiber strands is adjusted by adjusting the concentration of the sizing agent solution, a squeezing roller, strand tension, and the like.

When the sizing agent used in the present invention is attached to the carbon fiber strand, the form may be an aqueous solution,
An aqueous dispersion, a solution dissolved in an organic solvent, or the like is used, but an aqueous solution or an aqueous dispersion is preferable in consideration of a safe environment.

After the sizing agent is applied, the carbon fiber strand is dried. The drying means is not particularly limited,
Drying means generally used such as hot air drying, far-infrared drying, and drying with a hot roller may be used.

In order to produce a prepreg by applying a matrix resin to the carbon fiber strand of the present invention,
An ordinary hot melt method or a solvent method can be applied. The production of the prepreg by the hot melt method includes, for example, a method in which carbon fiber strands are aligned and arranged on a resin film to be a matrix resin, and a method of impregnating the strands with a roller or a method of supplying a resin from a slit to impregnate the strands is exemplified. , Is not particularly limited. The impregnation ratio of the matrix resin in the prepreg is usually 30 to 50% by weight.

The matrix resin used in the prepreg using the carbon fiber strand of the present invention as a reinforcing material includes:
Usually, a resin used as a matrix resin of a composite material using carbon fiber as a reinforcing material, for example, an epoxy resin, an unsaturated polyester resin, a polyimide resin, a bismaleimide-triazine resin, and the like are exemplified. It is preferable from the viewpoint of solubility and adhesiveness.

As the epoxy resin, bisphenol A
Type epoxy resin, polyfunctional epoxy resin such as tetraglycidylamine and triglycidylamine, and phenol novolak type epoxy resin. As curing agents and curing accelerators for these epoxy resins, commonly used amine curing agents such as disiamine diamide, diaminodimethyl urea, diamino diphenyl sulfone, imidazole curing agents, and acid anhydride curing agents are used. Is done.

The carbon fiber strand of the present invention has a sizing property,
Excellent spreadability and scratch resistance. A prepreg using this carbon fiber strand as a reinforcing material and a thermosetting resin as a matrix resin has good surface smoothness and impregnation. For this reason, the prepregs have the advantages of excellent adhesion to each other and easy lamination, and the composite material obtained by lamination has excellent mechanical properties (particularly, interlaminar shear strength).

[0030]

The present invention will be described below in more detail with reference to examples. In the examples, the rubbing amount, opening property, UD prepreg surface smoothness, impregnation property, and interlayer shear strength of the composite of the carbon fiber strand were based on the following methods.

(1) Scuffing amount of carbon fiber strands Five chrome-plated stainless steel rods each having a diameter of 2 mm are arranged at intervals of 15 mm, and the sized carbon fiber strands are arranged at an angle of 120 ° to the stainless steel rods. They were arranged in zigzag so that they could pass while contacting at a contact angle. The sized carbon fiber strands were zigzag between the stainless steel bars, and the tension was set at 200 g for unwinding the carbon fiber strands from the bobbin. The rubbed carbon fiber strand is coated with a urethane sponge (dimensions 32 mm x 64 mm x 10 mm, weight about 0.25
g) sandwiched between two pieces, put a weight of 125 g on the entire surface of the urethane sponge, and scrape the weight of the fluff attached to the sponge when the carbon fiber strand is passed at a speed of 15 m / min for 2 minutes. The amount of fluff was taken.

(2) Spreadability of Carbon Fiber Strand As shown in FIG. 1, a chrome-plated stainless steel rod 1 having a diameter of 15 mm and a width measuring device 2 are arranged. Next, the sized carbon fiber strand 3 is passed through the yarn path as shown in the figure at a speed of 5 m / min. The strand tension is set so as to be 200 g when passing through the width measuring device 2. The spread width of the carbon fiber strand passed between the stainless steel bars in this way is measured by the width measuring device 2. The measurement time was 30 seconds, and the average value during that time was measured.

(3) UD prepreg surface smoothness 70 parts by weight of EPN1138 (trade name: phenol novolak type epoxy resin) manufactured by Ciba Geigy Co., Ltd., 12 parts by weight of Epicoat 834 (trade name: bisphenol A type epoxy resin) manufactured by Yuka Shell Epoxy Co. , Epicoat 10
02 (trade name: bisphenol A type epoxy resin) 18
A curing agent and an accelerator were further added to the resin composition mixed in parts by weight to prepare a resin composition for prepreg. This resin composition was applied on release paper with a film coater to obtain a resin film. After arranging the carbon fiber strands sized on the resin film at equal intervals, the resin is impregnated into the carbon fiber strands by heating, and the UD having a carbon fiber weight of 150 g / m2 and a resin impregnation rate of 37% by weight is obtained. A prepreg was prepared. This UD prepreg was evaluated visually and tactilely.

(4) Impregnating property of UD prepreg In order to evaluate the impregnating property of carbon fiber strand with matrix resin (impregnating property of prepreg), the above-mentioned (3) was used.
The UD prepreg prepared in the above was cut into a size of 20 cm × 20 cm, and the prepreg was kept in a state in which release paper was stuck on one side, and used as a test piece for an evaluation test of the impregnation property of the prepreg. FIG. 2 is a simplified measuring device for evaluating the impregnating property of a prepreg. A prepreg test piece 6 cut so that the fibers are oriented in the circumferential direction of the half cylinder 5 is arranged on the inner wall surface of the half cylinder 5 having a radius of curvature of 16 cm, and the release paper side of the prepreg test piece 6 is placed in the half cylinder 5. Pasted. 5
After a lapse of minutes, remove the optional prepreg (5
(excluding cm), the number of voids generated in a square measuring area 7 of 5 cm × 5 cm was visually counted. This was measured at three different places, and the average value was evaluated as the impregnating property of the prepreg.

(5) Interlaminar shear strength of composite (abbreviation: ILSS) The UD prepreg produced in the above (3) is laminated so as to have a thickness of 3 mm after molding, put in a mold, and placed at 180 ° C. for 2 hours. At a pressure of 7 kg / cm 2 to produce a unidirectional carbon fiber reinforced molded plate (CFRP plate). This CFRP
The ILSS of the plate was measured at room temperature in accordance with ASTM-D-2344.

[0036]

Examples 1-3, Comparative Examples 1-4 Nichigo Polyester XWR930 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) as a polyester resin, and polyoxyethylene (15) lauryl represented by the following structural formula (2) as a polyether resin. Using glycidyl ether (POE (15) LGE: manufactured by Matsumoto Yushi Seiyaku Co., Ltd.), a resin composition having the compounding amount shown in Table 1 below was dissolved in water to prepare a sizing agent solution having a concentration of 15 g / l.

[0037]

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An unsized carbon fiber strand (Vesfight: registered trademark, manufactured by Toho Rayon Co., Ltd., 12,000 filaments, tensile strength 400 kgf / mm 2, tensile modulus 2450) was placed in a bath of this sizing solution.
0 kgf / mm2), the excess water was removed with a roller, and dried at 140 ° C for 3 minutes to continuously size the carbon fiber strand. The carbon fiber strand obtained in this manner has a fuzz amount, openability, U
The results obtained by measuring the surface smoothness, impregnating property, and ILSS of the composite according to the above-described method are shown in Table 1 below.
Shown in

[0039]

[Table 1]

[0040]

Examples 4 and 5, Comparative Example 5 Nichigo Polyester XWR 930 and Nichigo Polyester XWR 950 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) as polyester resins, and ethylene of bisphenol A represented by the following structural formula (3) as polyether resin. Oxide (10) adduct (PO
E (10) bisA) and polyoxyethylene (15) lauryl glycidyl ether (POE (15) LGE: manufactured by Matsumoto Yushi Seiyaku Co., Ltd.), dissolved in water, and isopropyl palmitate (Kao Corporation) as a third component. Exexel IPP) and octyl stearate (Negerbu OS, manufactured by Shin Nippon Rika Co., Ltd.) were added to prepare a water emulsion sizing agent for a resin composition having the compounding amount shown in Table 1.

[0041]

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Here, the emulsification of the third component is carried out in a ratio of 70 parts by weight of the third component, 10 parts by weight of polyoxyethylene (3) alkyl ether and 20 parts by weight of polyoxyethylene (8) alkyl ether. Mix to form an emulsion. The obtained water emulsion sizing agent was diluted with water so that the active ingredient concentration became 15 g / l, to prepare a sizing agent. In the bath of the water emulsion sizing agent, an unsized carbon fiber strand (Vesfight: registered trademark, manufactured by Toho Rayon Co., Ltd., 12,0
00 filament, tensile strength 400 kgf / mm2,
After immersion in a tensile elasticity of 24,500 kgf / mm2), excess water was removed with a roller, dried at 140 ° C. for 3 minutes, and the carbon fiber strand was continuously sized. Table 1 shows the results obtained by measuring the amount of fluff, the opening property, the UD prepreg surface smoothness, the impregnation property, and the composite ILSS of the carbon fiber strands thus obtained by the above-described methods.

[0043]

When a prepreg is produced using the sized carbon fiber strand of the present invention, the sized carbon fiber strand has good abrasion resistance and spreadability and is produced. The prepreg has good surface smoothness and impregnation, and a molded article formed using the prepreg has excellent composite physical properties. Also, the sizing agent can be used in the form of an aqueous solution or an aqueous dispersion and does not contain an epoxy resin component, so that the effect on the human body is reduced.

[Brief description of the drawings]

FIG. 1 is a simplified measuring device for evaluating the spreadability of a carbon fiber strand.

FIG. 2 is a simplified measuring device for evaluating the impregnation property of a prepreg.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stainless steel rod 2 Width measuring device 3 Carbon fiber strand 4 Carbon fiber strand package 5 Half cylinder 6 Prepreg test piece 7 Measurement area 8 Void

Claims (10)

[Claims] 1. A carbon fiber strand sized with a sizing agent containing a polyester resin and a polyether resin as essential components. 2. The sized carbon fiber strand according to claim 1, wherein the polyester resin is polyethylene terephthalate. 3. The sized carbon fiber strand according to claim 1, wherein the polyether resin is represented by the following chemical formula (1). Embedded image (In the formula, R1 represents an alkyl group having 1 to 30 carbon atoms, bisphenol A and a phenyl group, R2 represents hydrogen or a glycidyl group, and m represents an integer of 1 to 60.) 4. The polyester resin is polyethylene terephthalate, and the polyether resin is polyoxyethylene (m) lauryl glycidyl ether, or an ethylene oxide (m) adduct of bisphenol A (m).
Is an integer of 1 to 60). The sized carbon fiber strand according to any one of claims 1 to 3, wherein 5. The compounding amount of the sizing agent is 60 to 90% by weight for the polyester resin and 1 for the polyether resin.
The sized carbon fiber strand according to any one of claims 1 to 4, wherein the carbon fiber strand is 0 to 40% by weight. 6. The sized carbon fiber strand according to claim 1, wherein the amount of the sizing agent attached to the carbon fiber strand is 0.1 to 3.0% by weight. 7. The sized carbon fiber strand according to claim 1, wherein the sizing agent contains a higher fatty acid ester. 8. The sized carbon fiber strand according to claim 7, wherein the higher fatty acid ester is octyl stearate or isopropyl palmitate. 9. The sizing agent contains 5 to 20% by weight of a higher fatty acid ester.
And a sized carbon fiber strand according to claim 8. 10. The sized carbon fiber strand according to claim 1 is a reinforcing fiber, and
A prepreg characterized by using a thermosetting resin as a matrix.