JPH0457974A - Polycyanoaryl ether-coated carbon fiber and its production - Google Patents

Abstract

PURPOSE:To obtain the title carbon fiber excellent in flexibility, handleability and molding processability by coating carbon fiber with a specific polycyanoaryl ether resin. CONSTITUTION:The objective carbon fiber excellent in flexibility, handleability and molding processability can be obtained by immersing carbon fiber in an N-methylpyrrolidone solution of a ultra heat-resistant resin consisting of a polycyanoaryl ether with >=0.2dl/g in intrinsic viscosity having recurring unit of formula I (Ar is of formula II, III or IV). When the yarns of the present carbon fiber are made into a prepreg, this prepreg will be excellent in ply separation strength. It is preferable that the carbon fiber to be used be put, in advance, to oxidative treatment of its surface through e.g. electrolytic oxidation process so as to come to 0.1-0.5 in O/C value and <0.01 in N/C value.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides polycyanoaryl ether-coated carbon fiber suitable for use in robes, building materials, industrial structural materials, nets, automobile materials, OA equipment materials, sliding materials, etc. and its efficient manufacturing method.

[Prior art and problems to be solved by the invention] When producing complex-shaped products such as deep-drawn products using a composite material made of carbon fiber and super heat-resistant thermoplastic resin, commingle has traditionally been used. This is done by producing yarn or preform yarn, making it into cloth, laminating it, molding it, heating it, and pressing it.

However, in these methods, the resin does not satisfactorily impregnate the carbon fiber bundles, and as a result, the physical properties of the resulting product remain far from theoretical values and remain unreliable. This means that polyetheretherketone (PEEK)
The main reason for this was that the solution impregnation method could not be used because ultra-heat-resistant thermoplastic resins, such as those represented by (), do not dissolve at all in general-purpose organic solvents.

The method for manufacturing the above-mentioned commingle yarn is disclosed in, for example, Japanese Patent Application Laid-open No. 1983
It is disclosed in the publication No.-209033.

This method creates a yarn that is a blend of carbon fiber and thermoplastic resin fiber, and then crosses it.
This method is used to create objects with complex shapes, but because it involves winding a mixture of two types of yarn, carbon fiber and thermoplastic resin fiber, with different elongations and strengths, it is difficult to unwind from the bobbin. , tends to lint and is extremely difficult to handle.

In addition, because there are places where the carbon fiber bundles and resin fibers are clumped together, the carbon fibers and resin fibers are not dispersed well, and as a result, the strength of the molded product is only unreliable. Moreover, the appearance was also bad.

In addition, the manufacturing method of preform yarn is, for example,
It is disclosed in Japanese Patent No. 0-36156.

In this method, thermoplastic resin powder is placed between the carbon fiber bundles, and then the surrounding area is coated with resin to create a powder-filled carbon fiber coated yarn, which is then cross-shaped to create objects with complex shapes. Is it something to be manufactured?1
However, the powder is not uniformly distributed among the carbon fibers, and the carbon fibers and resin cannot be well dispersed.

Furthermore, both the commingling yarn and the preform yarn described above have the disadvantage that they require many steps and are expensive.

[Means to solve the problem]

As a result of intensive research aimed at solving these conventional problems, the present inventors found that certain polycyanoaryl ethers, which are a type of ultra-heat-resistant thermoplastic resin, work well in certain organic solvents. It has been discovered that it can be dissolved and uniformly impregnated between carbon fiber bundles, and based on this knowledge, the present invention has been completed.

That is, the present invention has a repeating unit represented by the general formula on the surface of the carbon fiber, and has an intrinsic viscosity of 0.
2 dl/g or more, preferably 0.3 to 2.0 dl/g
The present invention provides a polycyanoaryl ether-coated carbon fiber characterized by being coated with polycyanoaryl ether.

Such a polycyanoaryl ether-coated carbon fiber of the present invention can be produced, for example, by the method of the present invention shown below.

That is, the carbon fiber has a repeating unit represented by the general formula CI) and has an intrinsic viscosity of 0.2 dl/g.
This is a method of contact treatment with a solution of polycyanoaryl ether in N-methylpyrrolidone.

As the carbon fibers used in the method of the present invention, pitch-based or polyacrylonitrile (PAN)-based carbon fibers can be used, and pitch-based carbon fibers are particularly preferably used.

Such pitch-based carbon fibers use mesophase pitch containing a mesophase, which is an optically anisotropic phase, or optically isotropic pitch, for example, as pitch for spinning. These pitches are spun, and the fibrous pitch (pizziti fiber) is placed in the air at a temperature of usually 150 to 350°C.
After infusibility treatment at a temperature in the range of 350 to 1.000
Primary carbonization at 1,000-1.800°C
Examples include those obtained by secondary carbonization with C.

The carbon fiber used in the method of the present invention has a tensile strength of 20C1 to 500kg/am2. elastic modulus or 10
It is preferable that the amount is in the range of ~50 t/mm2. If the tensile strength is less than 200 kg/cm', the final strength of the polycyanoaryl ether coated fiber will be insufficient.

Furthermore, carbon fibers usually have a fiber diameter of 1 to 13 μm.
m1 is preferably in the range of 7 to 10 μm, and the number of filaments is 500 to 1 million, especially 2,000.
Preferably, the fiber bundle consists of ~24,000 fiber bundles.

In the method of the present invention, the surface of the raw carbon fiber as described above is
It is preferable to carry out oxidation treatment in advance if necessary.

Here, there are no particular restrictions on the method of surface oxidation treatment of carbon fibers, and commonly used methods such as electrolytic oxidation, gas phase oxidation, and chemical oxidation may be used. Moreover, it is industrially advantageous because various surface states can be obtained by changing the amount of power supplied, electrolyte, concentration, etc.

In this way, the surface of the carbon fiber is oxidized as necessary, but the oxygen atom/carbon atom (0/C
) is preferably in the range of 0.1 to 0.5, particularly 0.15 to 0.25, on the surface of the carbon fiber. Here, the value of oxygen atom/carbon atom (0/C) is 0
．． If it is less than 1, the adhesion with the resin will be poor; on the other hand, if it is 0.5
Exceeding this is not preferable because the strength of the carbon fiber decreases.

Similarly, nitrogen atoms/carbon atoms (N/
It is preferable to oxidize the surface of the carbon fiber so that the value of C) is less than 0.01. This is because some electrolytes, such as HNO, contain nitrogen atoms, and if they are not thoroughly cleaned, the nitrogen atoms will remain and have an adverse effect on the resin.

Furthermore, in the method of the present invention, the specific surface area is 0.05
It is preferable to use carbon fibers in the range of ~o, sOm/g. Here, the specific surface area of carbon fiber is 0.05 m/g
If it is less than 0.80 m, the adhesion with the resin will be poor.
/g, the strength of the carbon fiber decreases.

In the method of the present invention, as described above, carbon fibers whose surfaces have been oxidized as necessary have repeating units represented by the general formula CI) and have an intrinsic viscosity of 0.2 d.
A contact treatment is carried out with a solution of polycyanoaryl ether in N-methylpyrrolidone at a concentration of 1/g or more.

That is, a polycyanoaryl ether having a repeating unit represented by the general formula CI) and having an intrinsic viscosity of 0.2 dl/g or more is dissolved in an N-methylpyrrolidone solvent, and the above-mentioned polycyanoaryl ether is dissolved in an N-methylpyrrolidone solvent. If necessary, carbon fibers whose surfaces have been oxidized may be impregnated.

In the method of the present invention, as described above, a repeating unit represented by the general formula CI) and an intrinsic viscosity of 0.2
A polycyanoaryl ether of di/g or more is used.

The polycyanoaryl ether used in the method of the present invention has an intrinsic viscosity [η] of 0.2 dl/g or more at 60°C using p-chlorophenol as a solvent, preferably 0.3 to 2.0 dl/g. It is something.

If the intrinsic viscosity [η] is 0.2 dl/g, the amount of adhesion to the carbon fiber surface is small, uneven adhesion tends to occur, and the strength and heat resistance are also poor. A relatively large intrinsic viscosity [η] is advantageous because it increases strength and heat resistance, but if it exceeds 2.0 dl/g, moldability deteriorates.

Such polycyanoaryl ether preferably has a melting point of about 340°C, a glass transition point of about 145°C,
It is a super heat-resistant thermoplastic resin with a heat distortion temperature of about 165°C.

Specific examples of such polycyanoaryl ethers include the following formulas, and they can be produced, for example, by the following method.

Examples include homopolymers having repeating units such as or copolymers in arbitrary combinations.

These polymers can be produced by various methods. In the present invention, a solution of polycyanoaryl ether as described above in N-methylpyrrolidone is used. This solution may be prepared, for example, as follows: A powdery polycyanoaryl ether is used. Here, as the polycyanoaryl ether, one having a powder particle size of usually 1 to 100 μm, preferably 30 to 50 μm is used.

Powder of polycyanoaryl ether like this,
N-methylpyrrolidone (NMP) in a proportion of 1 to 25% by weight, preferably 10 to 25% by weight, and 180% by weight.
The temperature is raised to ~205°C, preferably 195-205°C. At that time, if the solution is stirred with a mixer, the solution can be obtained efficiently. Note that when the concentration of the solution is in the range of 20 to 25% by weight, it is better to use not only a mixer for stirring but also a homogenizer. Also, the temperature when raised is 18
If the temperature is below 0°C, the polycyanoaryl ether is difficult to dissolve, which is not preferable. On the other hand, if the temperature exceeds 205°C, NM
This is not preferred because evaporation of P is significant.

In the method of the present invention, carbon fibers as described above are impregnated in an N-methylpyrrolidone solution in which the polycyanoaryl ether obtained in this manner is uniformly dissolved, and the carbon fibers are coated with polycyanoaryl ether. Cover with ether (hereinafter sometimes simply referred to as resin).

The amount of resin coated on the carbon fibers varies depending on the impregnation speed of the carbon fiber bundle (2 hours), take-up tension, concentration of the solution, temperature, number of impregnations, etc., so the optimum conditions should be selected depending on the purpose. .

Generally, the amount of resin coated is usually 0.1 to 50% by weight, preferably 35 to 45% by weight of the total. If the coating amount of the resin is less than 0.1% by weight, the coating amount will be too small and the resin will not sufficiently penetrate between the carbon fiber bundles, resulting in uneven coating.

Furthermore, it is necessary to increase the number of times of impregnation.
Work efficiency decreases.

On the other hand, if the amount of resin coating exceeds 50% by weight, the yarn will have poor flexibility and will have poor moldability. Furthermore, since the content of the carbon fiber itself is reduced, the physical properties of the coated fiber are also reduced. Furthermore, it is necessary to slow down the impregnation rate, which reduces work efficiency.

When impregnating a carbon fiber as described above into an N-methylpyrrolidone solution of polycyanoaryl ether, the number of carbon fibers may be one, but usually 2,000 to 12.0 carbon fibers are used.
Used in bundles of 00 pieces. In addition, the impregnation rate is 0.1 to 2
m/min is appropriate, and the impregnation time is 30 seconds to 1
It is preferable to set it to 0 minutes.

Note that the take-up tension is suitably 5 to 100 g, and a flow may be applied to the liquid or ultrasonic waves may be applied so as to open the fibers in the impregnation tank. The number of times of impregnation is suitably 1 to 5 times, and may be carried out as appropriate depending on the amount of resin coating.

In the manner described above, the polycyanoaryl ether-coated carbon fiber of the present invention, in which the surface of the carbon fiber is coated with polycyanoaryl ether, can be produced.

The polycyanoaryl ether-coated carbon fiber of the present invention thus obtained can be further processed and used as composite materials such as sheet laminates and deep-drawn products.

Processing is carried out based on this polycyanoaryl ether coated carbon fiber yarn, but in this case,
The amount of resin coating is changed depending on the processing method. When processing yarns into yarns where flexibility is important, yarns with a small amount of resin coating are used, and yarns with a large amount of resin coating are used to improve material properties.

For example, to obtain a prepreg sheet, there are two methods: (1) producing resin-impregnated yarn with a carbon fiber content of 50 to 70% by weight, aligning it in one direction, heating, and pressing it, and (2) producing a carbon fiber yarn. A resin-impregnated yarn having a proportion of 90 to 99% by weight is prepared, stretched in one direction, sandwiched between polycyanoaryl ether films from both sides, and heated.

There is a method of obtaining it by pressing.

Moreover, a laminate can be obtained by laminating a plurality of prepreg sheets obtained in this way, molding them, and then heating and pressurizing them in an autoclave or hot press.

Furthermore, for deep-drawn products such as hemispherical objects, resin-impregnated yarn with a carbon fiber ratio of 50 to 90% by weight is prepared, this is made into a cloth, and molded using a matte die method, or a carbon fiber ratio of 50 to 90% is produced. It can be obtained by a method such as making a yarn impregnated with a resin in an amount of up to 90% by weight, sandwiching it between resin films, and performing diaphragm forming.

〔Example〕

Next, the present invention will be explained in detail with reference to examples.

Example 1 A bundle of 3,000 carbon fibers with a fiber diameter of 10 μm and a tensile strength of 230 kg/mm was used as an anode, a platinum plate was used as a cathode, and a nitric acid aqueous solution with a concentration of 0.01 mol/j' was used as an electrolyte. , continuous electrolytic oxidation by applying a voltage of 9 V to both electrodes, the specific surface area was 0.35 ttf/g, the surface oxygen atom/carbon atom (0/C) value was 0.24, and Nitrogen atom/carbon atom (N/C) value is 0.01
less carbon fiber was obtained. In addition, oxygen atom/carbon atom (
0/C) value and the nitrogen atom/carbon atom (N/C) value were both measured using an X-ray photoelectron spectroscopy (XPS) device.

Using this carbon fiber, polycyanoaryl ether/
Impregnation treatment was carried out continuously in N-methylpyrrolidone solution (concentration 25% by weight). The processing speed is 0.5m/
I did it in minutes.

In addition, the polycyanoaryl ether in this case has a repeating unit represented by, and its intrinsic viscosity [η
] is 1.20 di/g, and the glass transition temperature is 145
The °C1 melting point was 340°C. In addition, the polycyanoaryl ether/N-methylpyrrolidone solution (concentration 25% by weight) was obtained by dissolving 500 g of the above polycyanoaryl ether in N-methylpyrrolidone No. 21, and the impregnation was maintained at 200°C. I did it.

After the impregnation treatment, the solvent N-methylpyrrolidone was removed at 250°C to obtain a carbon fiber/polycyanoarylether yarn.

By repeating the above operation twice, a continuous yarn of carbon fiber/polycyanoaryl ether=60% by weight/40% by weight was obtained. This was pulled in one direction, heated to 370° C., and pressed at 40 kg/al to obtain a prepreg sheet with a thickness of 0.125 mm.

20 of these prepreg sheets were laminated and then heated to 370"C again.
, 40 kg/Ci to prepare a test piece, and the interlaminar shear strength (ILSS) was measured. This ILSS
The measurement shows the interfacial adhesive strength between carbon fiber and resin (polycyanoaryl ether), and is based on ASTM D
The test was carried out in accordance with 2344.

ILSS was 1189 kg/ad, which was very excellent.

Example 2 In Example 1, the fiber diameter was 9 μm and the tensile strength was 370
kg/at, specific surface area is 0.30rd/g, surface oxygen atom/carbon atom (0/C) value is 0.17, nitrogen atom/carbon atom (N/C) value is less than 0.01. An experiment was conducted in the same manner as in Example 1 except that a bundle of 3,000 carbon fibers was used.

The ILSS measurement result was 1295 kg/cd, which was very excellent.

Reference Example 1 In Example 1, polyether ether ketone (manufactured by IC1, V
ICTREX PEEK 380P, Kurts transition temperature 45°C, melting point 345°C] powder was placed in N-methylpyrrolidone and stirred at 200°C, but the polyetheretherketone powder did not dissolve.

Example 3 Experiments were conducted in the same manner as in Example 1, except that polycyanoaryl ether having a repeating unit represented by the following formula (intrinsic viscosity: 1.5 dl/g) was used as the polycyanoaryl ether. I did this.

The ILSS measurement result was 1052 kg/car, which was very excellent.

Example 4 In Example 1, polycyanoaryl ether 100
g, 2I! Dissolved in N-methylpyrrolidone solution of 2
Example 1 except that it was processed once at a processing speed of m/min.
A carbon fiber/polycyanoaryl ether yarn was obtained in the same manner as above.

When a plain weave cloth was made using the yarn obtained in this way, no fuzzing of the carbon fibers was observed.
A good loss was made.

Example 5 In Example 1, except that the number of impregnations was one time,
A carbon fiber/polycyanoaryl ether yarn was obtained in the same manner as in Example 1.

A plain weave cloth was made from the yarn thus obtained. Place this into a hemispherical brass mold with a radius of 5 cm.
The sheets were laminated, heated (370°C), and pressed (100 kg/car) using a matte die method.

As a result, a hemispherical deep-drawn product with excellent moldability and appearance was obtained.

〔Effect of the invention〕

According to the method of the present invention, the bundles of carbon fibers can be uniformly and completely impregnated with polycyanoaryl ether, which is a super heat-resistant thermoplastic resin.

Therefore, the yarn obtained by processing the polycyanoaryl ether-coated carbon fiber obtained by the method of the present invention has excellent flexibility, handleability, and molding processability, and has a simple process and is economically superior.

Furthermore, when this yarn is made into a prepreg, it has excellent interlayer peel strength (ILSS), and furthermore, by forming it into a cloth, deep drawing can be performed.

Claims (2)

[Claims] (1) On the carbon fiber surface, there are general formulas▲mathematical formulas, chemical formulas, tables, etc.▼……[I] [In the formula, Ar is▲mathematical formulas, chemical formulas, tables, etc.▼, ▲mathematical formulas, chemical formulas, tables, etc. Indicates ▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼. ] It has a repeating unit represented by and has an intrinsic viscosity of 0.
A polycyanoaryl ether-coated carbon fiber characterized by being coated with 2 dl/g or more of polycyanoaryl ether. (2) Carbon fiber, general formula▲There are mathematical formulas, chemical formulas, tables, etc.▼……[I] [Ar in the formula▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Or ▲There are mathematical formulas, chemical formulas, tables, etc.▼. ] It has a repeating unit represented by and has an intrinsic viscosity of 0.
2. The method for producing polycyanoaryl ether-coated carbon fibers according to claim 1, wherein the polycyanoaryl ether is contacted with a solution of 2 dl/g or more of polycyanoaryl ether in N-methylpyrrolidone.