JPH03182306A - Pellet used for manufacture of carbon fiber reinforced plastic and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the strength and the shock resistant property of a molded form by a method wherein the film or the fiber of thermoplastic resin or thermosetting resin is wound around the periphery of a string like material of pitch based carbon fibers, whose diameter is specified. CONSTITUTION:The string like carbon fiber, obtained by carbonizing pitch fiber manufactured through melt-blown spinning, centrifugal spinning or span- bond spinning and having the diameter of 0.5-10mm, is carbonized further if necessary and, thereafter, a tube is formed by fusion-welding or bonding one row to two rows or more of film like material or thread like material of thermosetting resin or thermoplastic resin, for example, the film like material is wound around the tube to stabilize the configuration of the resin by a method wherein the string like material is received into the hollow part thereof or the like, further, the material is cut into proper length whereby pellets are obtained. The pellets are used as material for forcing them into the mold of injection molding, transfer molding or the like of carbon fiber reinforced plastic.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to pellets used in the production of carbon fiber reinforced plastics having excellent strength and impact resistance.

The present invention provides a method for reinforcing plastics with carbon fibers made from pitch fibers produced by melt-blowing, centrifugal spinning, or spunbond methods during injection molding or transfer molding. It is difficult to mix uniformly, and if strong kneading is applied, it will be cut into short pieces, so the strength and impact resistance of molded products cannot be sufficiently improved.

According to the manufacturing method of the present invention, the reinforcing fibers are well dispersed in the matrix resin, and a uniform molded product can be obtained without applying strong shearing, so there is less cutting of the reinforcing fibers.
As a result, an excellent reinforcing effect can be obtained. In addition, since the reinforcing fibers can be produced from pitch fibers produced by melt-blowing, centrifugal spinning, or spunbonding, which are relatively easy to produce, they have the advantage of being low in price.

The pellets of the present invention have almost no fiber damage at the time of manufacture, and are not bulky, so fiber agglomeration (skewing) due to insufficient mixing during molding does not occur. It rarely causes a lack of energy.

The carbon fiber reinforced plastic manufactured by the manufacturing method of the present invention has excellent mechanical properties as well as dimensional stability, low creep,
It has low thermal expansion, high heat distortion temperature, excellent lubricity, fairly high electrical conductivity, antistatic performance, electromagnetic shielding ability, etc., and is suitable for mechanical parts, especially those that require dimensional accuracy, bearings, seals, etc. It can be used in items that require sliding properties such as gas getters and packings, items that require self-lubricating properties, casings for electronic devices, containers with static elimination functions, etc.

(b) Conventional technology Fiber-reinforced plastics with a matrix of thermosetting resin such as unsaturated polyester resin or epoxy resin can be produced using the filament winding method, in which fibers impregnated with thermosetting resin are wound around a mandrel and cured, or by thermosetting. It is formed by a hand lay-up method, etc., in which an appropriate number of cloth impregnated with a synthetic resin is stacked on a mold and left to stand, or hardened by applying pressure.

These molding methods cause less damage to reinforcing fibers,
Although it is possible to provide molded products with excellent strength and impact resistance, the filament winding method has limitations in the shapes that can be molded, and the hand lay-up method has the drawback of requiring labor and low productivity. In addition, both have the disadvantage that processing accuracy cannot be improved so much and thermoplastic resin cannot be used as a matrix.

In order to solve these drawbacks, thermoplastic resin or thermosetting resin is kneaded with chopped or milled reinforcing fibers, then cut into appropriate sizes, which are then used as raw materials for injection molding or transfer. Molding is performed. This method certainly has good productivity and dimensional accuracy, but the amount of reinforcing fibers that can be mixed is much smaller than that of filament winding or hand layup, and the reinforcing fibers are short during kneading. Since it is cut, there is a problem in that it does not have a sufficient reinforcing effect.

In addition, as reinforcing fibers, short fibers of irregular length or long fibers opened into a planar shape, such as glass 1m fibers manufactured by melt-blown method, centrifugal spinning method, or spunbond method, or carbon fibers made from pitch fibers, are used. There are some problems that make it difficult. In the case of glass fibers, the low cost of continuous fibers is not a big problem, but in the case of carbon fibers, the cost difference between continuous fibers and short fibers of irregular length is large, making it difficult to use low-cost short fibers. Something becomes a big problem.

In order to solve such problems, the SMC method and the Bl(C method) are carried out, in which a mat-like material of reinforcing fibers is impregnated with a thermosetting resin and then molded using a powerful molding machine such as a press.

This method certainly has good productivity and good dimensional accuracy, but it requires a powerful molding machine and a durable mold, so it has the disadvantage of high costs unless you produce large quantities of the same molded product. Also, since it is difficult to cause large deformation during molding, there are considerable restrictions on the shape of the molded product. In particular, when the mat-like material is made of short fibers of irregular length or uncut long fibers such as spunbond, there is a problem that the deformation rate can only be kept small.

It has also been known for a long time to mold cloth or paper cut into several squares by mixing it with thermosetting resin, but since the fluidity of the molding material becomes poor, the structure of the cloth or paper during kneading is It has been thought that it is difficult to mix large amounts of fibrous materials by such a method because of the destruction of the fibers and the cutting and crushing of the fibers.

Fiber reinforced plastics whose matrix is thermoplastic resin such as polyamide, polyester, polyolefin, etc.
Conventionally, molding materials have been used such as injection molding and other methods using molding raw materials such as velvet mixed with reinforcing fibers.

Methods for producing molding raw materials include (1) simply mechanically mixing fibers cut into appropriate lengths and powdered or granular resin, (2) dissolving or suspending the resin in a solvent, and then cutting. (3) dissolving or suspending the resin in a solvent;
(4) Mix reinforcing fibers cut into appropriate lengths with powder or granular resin and extrude them using an extruder. (5) A method of plasticizing and melting the resin using an extrusion molding machine, continuously introducing long fibers to the discharge side of the melt, allowing the resin melt to penetrate into the fibers, extruding it, and cutting it. etc. are known.

In all of these methods, when the reinforcing fibers are continuous fibers, the conditions for forming the reinforcing fibers without causing severe damage to the fibers are known. However, when using short fibers of undefined length to form 1m reinforcing fibers, it is generally difficult to form them using methods (1) and (2) due to the bulk of the forming raw material itself, and in many cases, the reinforcing fibers are may aggregate and the expected performance may not be obtained.
Methods (3), (4), and (5) are methods in which it is difficult to use short fibers of indefinite length or long fibers that have already been opened as reinforcing fibers.

In order to solve these problems, Japanese Patent Application Laid-Open No. 43-7448
In this issue, long glass fibers are pre-impregnated with a solution of a matrix resin, and after drying the solvent, they are introduced into the discharge side of the plasticized and molten matrix resin, the fibers are coated with resin, extruded, and cut into pellets. Discloses technology to Although this technique is certainly an excellent method for efficiently producing pellets with good moldability, short fibers of undefined length cannot be used as reinforcing fibers.

Furthermore, Japanese Patent Publication No. 44-25911 discloses a method in which short glass fibers preheated to a temperature higher than the softening temperature of the resin are forcibly fed into a hopper of an extruder using a rotary feeder and kneaded. This method has the advantage of good fiber dispersion and less fiber breakage because the short glass fibers soften the resin pellets and adhere to the surface, but as the fiber content increases, fiber agglomerates suddenly form. This has the disadvantage that it is generally difficult to produce products with a high fiber content.

Furthermore, in JP-A No. 64-26652, a carbon fiber mat of indefinite length is impregnated with a liquid thermosetting resin, and then kneaded and cut using a specially shaped extruder such as a mincing mixer to produce 100 parts of fibers. A technique for obtaining a lump resin in which a resin content of 0.5 to 10 parts by weight is mixed is disclosed. Although this technology can certainly mix fibers and resin uniformly and generally make the fiber length uniform, there is a problem that reducing the amount of resin generally makes the fibers too short, so it is difficult to make the reinforcing fibers of composite materials From the viewpoint of adhesion between the fiber and the matrix resin, it is desirable that the resin content at this stage be 10 parts by weight or less, whereas from the viewpoint of fiber length, it is sufficient that the resin content at this stage is not more than 30 parts by weight. It is difficult to maintain the length of the resin, and when the fiber length is increased, the fibers in the resin mass become too entangled.
There is a problem that the boundaries of the lumps do not disappear even after molding.

Among these problems with conventional technology, fiber cutting, crushing, and agglomeration occur more frequently with carbon fibers than with glass fibers, and this, coupled with the high cost of carbon fibers, makes it difficult to expand its use. This is a strong impeding factor.

(c) Problems to be Solved by the Invention The present invention uses the melt-prone method and the reinforcing fiber when molding carbon fiber-reinforced plastics using high-efficiency, high-precision molding methods such as injection molding and transfer bottom molding. The purpose is to solve the problem that it is difficult to use short fibers of irregular length, such as those produced by centrifugal spinning, or long fibers opened into a sheet shape, such as those produced by spunbond. .

When molding fiber-reinforced plastics, using short fibers of irregular length, such as those produced by melt-blowing or centrifugal spinning, as reinforcing fibers makes it easier to align and supply the fibers in the subsequent process. Because of this difficulty, the resulting fiber aggregate is bulky, making it difficult to mix the reinforcing fibers and the matrix resin, and entanglement occurs between the fibers, causing only the fibers to form an agglomerate, resulting in a poor resin-to-fiber ratio. Since large fluctuations tend to occur, there is a problem that molding methods are extremely limited.

For this reason, in the case of glass fibers, long fibers are cut into fixed lengths to be used as reinforcing fibers, but in the case of carbon fibers, since the cost of long fibers is high, it is considered that it is more valuable to use short fibers with irregular lengths.

(d) Means for Solving the Problems The present invention provides thermoplastic fibers in carbon fibers having a diameter of 0.5 to 10 mm, which are obtained by carbonizing pitch fibers produced by melt-blown spinning, centrifugal spinning, or spunbond spinning. Carbon fiber reinforcement characterized by wrapping a film or thread of resin or thermosetting resin, stabilizing the form of the resin by heat treatment, adhesion, fusing, etc., and then cutting it into appropriate lengths. A plastic pellet for molding and a method for producing the same.

Melt-blown spinning used in the production of pitch fibers in the present invention is a method in which molten pitch is spun into a high-speed air stream through a spinning hole or slit having an outlet.

Melt blown methods include a method in which spinning holes are arranged in a line or a slit is provided in a slit-shaped high-speed airflow discharge hole, and a method in which one or several spinning holes are provided in a thank-you letter high-speed airflow discharge hole. is known, but either method can be used for the present invention.

The pitch used in the present invention is a high softening point pitch that can be melt-spun and infusible. The pitch may be isotropic, but preferably is a mesophase pitch. Carbon fiber obtained from mesoface pitch has strength,
It has a high elastic modulus and exhibits excellent performance as a reinforcing fiber.

As shown in FIG. 1, one embodiment of a method for collecting melt-spun pitch fibers in the form of strings is as shown in FIG.
In this method, when forming a sheet-like III fiber aggregate, the rear end of the point where suction ends is made oblique to the traveling direction of the belt. At this time, as shown in Figure 2 (B), it is also possible to simply move from one side to the other, delaying the position where suction ends, and making it diagonal. HJ can be combined to form a ■ shape as shown in Figure 2 (a), and many of these can be combined to form a third shape.
It can be serrated in shape as shown in the figure.

By slanting the rear end of the suction point from one end of the belt toward the other, it is possible not only to narrow the width of the sheet-like aggregate of pitch fibers, but also to place the sheet-like aggregate on one side of the belt. It can be guided and, if necessary, focused. It is also possible to place the bundled pitch fibers as they are on a belt and send them to the infusibility treatment equipment, or they can be transferred diagonally to the belt, given a weak twist, and wound onto a bobbin, or made into a top shape. It is also possible to store it in a can that can be rolled up.

By making the suction position serrated as shown in FIG. 3, the sheet-like aggregate of pitch fibers can be divided into a plurality of fibers in parallel, and the width thereof can be reduced. For example, by making the sawtooth shape into one inverted square shape, the sheet-like aggregate of pitch fibers can be divided into several pieces and guided in a tow shape on both sides of the belt.

In another embodiment of the present invention, as shown in FIG. 4, the width of the suction point provided on the back surface of the belt in the direction perpendicular to the direction of travel of the belt is gradually narrowed in the direction of travel of the belt. This method reduces the width of the sheet-like aggregate of pitch fibers and guides them to a specific position on the belt.

The method of inducing such a sheet-like material of pitch fibers into a string-like or tow-like shape can be used not only in the melt-blown method but also in the centrifugal spinning method and the spunbond method.

In yet another embodiment of the present invention, a method is used in which pitch fibers are carbonized and then the fibers are aligned using a card machine used for spinning. At this time, it is desirable to use two carding machines, with the first carding machine mainly cutting the fibers and the second carding machine mainly pulling and aligning the pitch fibers. It is preferable to adopt conditions where the elongation of the fibers is large.The fibers drawn by the carding machine may be processed into pellets as they are in the form of slivers, or they may be processed after being thinned by drafting. Good. You can also process it after twisting.

The pitch fiber or carbon fiber string produced in this way is further carbonized if necessary to form a carbon fiber string, and then converted into a film or thread of thermoplastic resin or thermosetting resin. The resin is wound, the shape of the resin is stabilized by heat treatment, adhesion, fusion, etc., and the resin is cut into appropriate lengths to form pellets. These pellets have excellent performance as a material for press-fitting carbon fiber-reinforced plastics into molds such as injection molding and transfer molding. At the time of molding, a resin that will become a matrix component is mixed at the same time or in advance and molded. Preferably, the resin is mixed with the resin that will be a matrix component in advance.

In one specific embodiment of the present invention, a thermoplastic resin or thermosetting resin film or thread-like material is wound around a carbon fiber string-like material, in which the film-like material or thread-like material has a hollow shaft. Wrap it around a bobbin, and while rotating the bobbin while feeding the string-like object through the hollow part of the shaft, the film-like object or thread-like object that is swung away from the bobbin is sent in the same direction from the inlet of the string-like object and wound around the string-like object. There is a way to unwind it.

Although this method has the drawback of not being able to use a film with a large width, it can increase the winding speed and efficiently fix the thermosetting resin or thermoplastic resin to the string-like object.

In another specific embodiment of the present invention, a thermoplastic resin or thermosetting resin film or thread is wound around a carbon fiber string. There is a method in which a tube is formed by fusing or gluing two or more rows of wires, and the string-like material is stored in the hollow portion of the tube.

This method is particularly advantageous when using film materials. Two sheets of #1 slit film are supplied, a string-like object is sandwiched between these films, and both sides of the film are crimped or heat-sealed. Such devices are widely commercially available as packaging machines. The number of films to be supplied is 1
It is also possible to make a sheet, fold it, sandwich a string-like object, and press or heat seal the open side.

In yet another embodiment of the present invention, a thermoplastic resin or thermosetting resin film or thread-like material is wound around a carbon fiber string-like material. After winding, there is a method in which both ends of the film-like material or thread-like material are twisted and fixed, and if necessary, the twisted portions are fused or bonded.

This method is convenient for using threads.

In this method, a molten liquid substance can be used as the filamentous substance. In order to twist the liquid yarn, it is preferable to use false twisting using a gas vortex. A knitting machine can be used as a method of twisting the yarn. It is possible to form a tube by warp mai, and it is possible to form a tube by winding yarn using a weft knitting machine. It is also possible to wind the thread using a mechanism similar to a zigzag sewing machine.

Another embodiment of the method for winding a thread-like material or a film-like material in a liquid state is to wrap a thermoplastic resin or thermosetting resin film or thread-like material around a carbon fiber string-like material. is sent through a die, the liquefied resin is discharged from the discharge hole provided around the die, and the resin solidifies to form a film-like material or thread-like material that is alternately twisted and wound into a string-like material. If necessary, there is a method of fusing and fixing the film-like material or thread-like material. This method has the disadvantage that the equipment is somewhat complicated, but
Suitable for high-speed processing and excellent for industrial production.

In the present invention, the carbon fiber string is preferably obtained by carbonizing melt-blown pitch fibers that are bundled by an air flow when collected on a porous belt.

In the melt spinning of pitch by the melt blown spinning method, the temperature of the molten pitch is preferably 10 to 70°C higher than the softening point of the pitch, and the temperature of the gas spouted from around the spinning hole is preferably the temperature of the molten pitch. The temperature should be approximately the same as or 200°C higher. The gas ejected from around the spinning hole is preferably air, water vapor, or combustion waste gas, and the flow rate is preferably 0.1 to 1 times the speed of sound, as measured at the gas discharge hole.

The spun pitch fibers are subsequently collected on a porous belt-E. It is preferable to collect the fibers by suction from the back side of the belt, and to transfer the fibers to the vicinity of the belt, use gas ejected from around the spinning holes.

At this time, it is also possible to use an aspirator or the like as an aid. When collecting on a porous belt, there is an advantage that it can be formed into a relatively uniform mat-like form, and in particular, it is possible to handle the extremely brittle pitch fibers without applying force. Pitch fibers can be formed into a string shape on a porous belt, and then infusible and carbonized while being placed on the belt.

Melt-blown fibers use simpler spinning equipment than conventional pitch fibers, so they are lower in cost.
In addition, since the fibers are produced in the form of suspended air currents, they have the advantage of being easy to collect in the form of strings.The pellets of the present invention have the advantage that they can be easily collected in the form of strings of pitch fibers by using strings of pitch fibers as raw materials. , it is possible to obtain molded products at lower cost than conventional carbon fiber reinforced plastics.

In the present invention, the melt-blown fibers are preferably not continuous filaments, but are naturally cut during the spinning process. It is a short fiber of irregular length. These short fibers of irregular length generally have a wide fiber length distribution, ranging from a number of fiber lengths to several dozen. In the case of short fibers having an irregular length rather than continuous length fibers, they are less likely to be bundled by airflow and tend to form a structure that allows uniform impregnation during molding.

In the present invention, the carbon fiber string can be made by centrifugal spinning of pitch. In this method, molten pitch is extruded through a die rotating at high speed and formed into a thread. Once the fibers blown away from the die are received on the cylindrical receiver surrounding the die, a second doughnut-shaped receiver that rotates slowly is placed under the cylindrical receiver due to its own weight.
is deposited on the receiver. A scraping guide is provided at one location in the second receiver, and the accumulated fibers are pulled out and made into a string-like material.

This method has the advantage that the equipment is simple and inexpensive, and it is easy to operate, but there is a problem that the scraping guide easily damages the fibers. This method has the advantage of less damaging the fibers and less variation in the thickness of the tow. The collected fiber aggregate can be bundled into a string by making the rear end of the suction area oblique to the traveling direction of the belt.

Another embodiment of the carbon fiber string-like material in the present invention is a sliver made by passing short carbon fibers through a card. The sliver may be made by cutting long fibers of carbon fibers, but since the cost is high, it is preferable to manufacture the sliver from a sheet-like fiber aggregate made by a melt-blown method, a centrifugal spinning method, or a spunbond method. In this case, it is more preferable to use two types of cards, with the first card cutting the fibers and the second card aligning the fibers.

(E) Function The present invention solves the problem of reducing the reinforcing effect due to cutting of carbon fibers when carbon fiber reinforced plastic is molded by injection molding or press-fitting into a mold such as a transfer bottom shape. The purpose is to

Cutting of carbon fibers also occurs during the final molding stage, but the most severe breakage occurs during the production of molding pellets.
This is due to kneading. The strength of kneading required varies greatly depending on the ease with which the molding materials are mixed, and since the pellets of the present invention are easy to mix, this kneading step can be weakened and fiber breakage can be prevented.

The reason why the kneading process can be weakened is that, unlike conventional carbon fibers, carbon fibers manufactured by melt-blown spinning have bends and crimps in the fibers, making it easy for resin to enter the gaps between the fibers. . Therefore, without applying strong shear to the resin, you can simply pour it under high pressure,
It is presumed that this is because the resin and fibers are mixed uniformly simply by removing the air between the fibers using a vacuum.

<Example> Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Using petroleum pitch with a softening point of 285°C and an optical anisotropy fraction of 100% as a raw material, spinning with a diameter of 0.8 and a built-in tubular nozzle for discharging raw material with an inner diameter of 0.3 and an outer diameter of 0.6 mm. Using a spinneret with holes, twisting air was blown out from around the tubular nozzle to pull the molten pitch and perform spinning. Pitch discharge amount, 12g/80H・min, pitch temperature 310°C, mouth temperature 370°C, twisting air flow rate 0.40kg/min, twisting air temperature 370°C, twisting air pressure 1,5 ki
/ cd Q.

The spun fibers were collected on the belt by suction from the back side of a belt made of stainless steel wire gauze having a collection portion of 20 meshes. The shape of the suction port was as shown in FIG. 2 (b), and the pitch fibers deposited in a sheet shape were bundled into a tow shape.

The width of the suction port is 30 m, 1llfi before shrinkage starts.
The length measured in the traveling direction of the belt from the starting point of the small end to the rearmost end of the suction port was 50 cm.

The obtained tow was treated to be infusible by a conventional method and then carbonized at a maximum temperature of 1000° C. to obtain a tow with a thickness of about 120,000 deniers. The fiber performance was an average fiber diameter of 10.5 μm, specific gravity of 1.85, tensile strength of 140 kg f/mf, tensile modulus of elasticity of 12.8×10′ bgf/ml, and elongation of 1.01%. A nylon 6 film having a width of 6 circles and a thickness of 16 μm was wound around this string-like material made of short and irregular length carbon fibers, and after spot welding using ultrasonic waves at one pitch, the string was cut into four lengths. The resin content of the obtained pellets was 4.2%.

70 parts of nylon 6 pellets were mixed with 30 parts of these pellets, and injection molding was performed.

In this mixture, the fibers were sufficiently dispersed by the screw of the molding machine without preliminary kneading, and a molded product with excellent performance was obtained. The printer temperature was 270°C, the screw rotation speed was 6 ORPM, the mold temperature was 82°C, and the molding cycle was 55 seconds. Table 1 shows the results of comparing the performance of the obtained molded products with those not reinforced with fibers and those reinforced with milled fibers.

Table 1 Performance example of carbon fiber reinforced nylon 2 In place of the nylon film of Example 1, a film with a thickness of 20 μm was used.
When the PBT film was used, a molded article with excellent fiber reinforcing effect was obtained as in Example 1.

Example 3 When a polypropylene film or an A8S resin film was used in place of the nylon film of Example 1, a molded article with excellent fiber reinforcing effect as in Example 1 was obtained.

Example 4 Instead of the nylon film of Example 1, thermosetting vinyl ester resin (Showa Kobunshi R3-7030) 100
A mixture of 1 part, 6 parts of epoxy acrylate thickener (Lipoxy L manufactured by Showa Kobunshi Co., Ltd.), 0.5 part of zinc stearate, and 1 part of benzoyl peroxide was poured onto a glass plate and heated at 20°C for 2 hours.
The resulting sheet was left to stand for 4 hours and had a thickness of 50 μm. This sheet-like material was wound around the same carbon fiber string-like material as in Example 1, and cut into 3.5-inch lengths to produce pellets.

To 4◇ parts of these pellets, 60 parts of thermosetting resin pellets having the same composition as the above sheet-like material were mixed, and the mold temperature was 1.
When injection molding was performed at 65°C, it showed good mechanical and electrical properties.

Example 5 In place of the nylon 6 film in Example 1, 100 parts of an epoxy resin monomer (Epicoat 828 manufactured by Shell), 20 parts of a curing agent (Evicure Z manufactured by Shell), and acetone 6□
7 parts of the mixture was poured onto a polyethylene film and dried at room temperature for 5 hours to obtain a film with a thickness of 60 μm. This film was slit together with the polyethylene film, the epoxy resin side was placed in contact with the carbon fiber string, and the two sheets were stacked and pressed together. The film was further cured under pressure at 80°C for 60 minutes, and the polyethylene film was peeled off. , this is 31
The molded phase pellets were cut into 1 Ill length.

When these pellets were mixed with epoxy resin pellets produced in the same manner as above and injection molded at a mold temperature of 150° C., good mechanical and electrical properties were exhibited.

Example 6 When a spunbond spinning machine was used instead of the spinning machine of Example 1, similarly excellent molded phase pellets of carbon fiber reinforced resin were obtained.

Example 7 When a spinning machine using a centrifugal spinning method was used instead of the spinning machine of Example 1, similarly excellent molding pellets of carbon fiber reinforced resin were obtained.

Example 8 A 75 denier polyester filament was used instead of the nylon 6 film of Example 1, and the fiber was wound around a carbon fiber string using a zigzag sewing machine.
It was cut into 4 lengths to make pellets. This pellet has P
When BT@fat pellets or PUT resin pellets were mixed and injection molded, a carbon fiber-reinforced resin molded product with excellent performance was obtained as in Example ρ11.

(G) Effects of the Invention The present invention relates to a method for producing carbon fiber reinforced plastics having excellent strength and impact resistance, and pellets used in the production.

In the case of injection molding or transfer molding, the present invention is reinforced with carbon fibers made from pitch fibers produced by melt-blowing or centrifugal spinning, or spread long-fiber carbon fibers such as spunbond. In conventional methods, it is difficult to mix reinforcing carbon fibers uniformly, and if strong kneading is applied, the carbon fibers are cut into short pieces, so the strength and impact resistance of the molded product cannot be sufficiently improved.

According to the manufacturing method of the present invention, the reinforcing fibers are well dispersed in the matrix resin, and a uniform molded product can be obtained without applying strong shearing, so there is less cutting of the reinforcing fibers.
As a result, an excellent reinforcing effect can be obtained. Furthermore, since the reinforcing fibers are made from pitch fibers produced by the melt-prone method, centrifugal spinning method, or spunbond method, they have the advantage of being low in price.

The pellets of the present invention have almost no fiber damage at the time of production, and are not bulky, so fiber aggregation hardly occurs due to insufficient mixing during molding, and lack of degassing during the molding process. rarely occurs.

The carbon fiber reinforced plastic manufactured by the manufacturing method of the present invention has excellent mechanical properties as well as dimensional stability, low creep,
It has low thermal expansion, high heat distortion temperature, excellent lubricity, fairly high electrical conductivity, flilJ@ performance, electromagnetic shielding ability, etc., and is suitable for mechanical parts, especially those that require dimensional accuracy, bearings, seals, etc. It can be used for things that require sliding properties such as gas getters and packings, things that require self-lubricating properties, gauging equipment for electronic equipment, containers with static elimination functions, etc.

[Brief explanation of drawings]

FIG. 1 is a schematic view of an apparatus for producing carbon fiber strings, which are the raw material for the pellets of the present invention, as viewed obliquely from above. FIG. 2 is a schematic diagram showing the shape of the suction port and the situation in which a string-like object is formed from a sheet. FIG. 3 is a schematic view of a device for dividing and collecting carbon fiber strings, as seen diagonally from above. FIG. 4 is a schematic diagram showing an example of a suction port whose width becomes narrower stepwise in the direction of belt movement, and how a string-like object is formed by the suction port. 1...Spinning machine 2...Suction port 3...Belt 4...Tow and above

Claims (11)

[Claims] (1) Wrap a thermoplastic resin or thermosetting resin film or fiber around a pitch-based carbon fiber string with a diameter of 0.5 to 10 mm, and reduce the carbon fiber content to 8.
A pellet used for manufacturing carbon fiber reinforced plastic, characterized in that the content is 0 to 99.5% by weight. (2) A film-like material of thermoplastic resin or thermosetting resin is added to a carbon fiber string-like material with a diameter of 0.5 to 10 mm obtained by carbonizing pitch fibers produced by melt-blown spinning, centrifugal spinning, or spunbond spinning. Alternatively, a filamentous material is wound around the carbon fiber content of 80 to 99.
1. A method for producing pellets used in the production of carbon fiber reinforced plastics, which comprises stabilizing the form of the resin by heat treatment, adhesion, fusion, etc. to 5% by weight, and then cutting the pellets into appropriate lengths. (3) A pellet for use in producing a carbon fiber reinforced plastic, characterized in that the carbon fiber reinforced plastic according to claims 1 and 2 is molded by press-fitting into a mold. (4) In the molding of the carbon fiber reinforced plastic according to claims 1 to 3, the carbon fiber reinforced plastic is molded by mixing a matrix resin at the same time or in advance when the pellets are press-fitted into the mold. Pellets used in plastic manufacturing. (5) When winding the thermoplastic resin or thermosetting resin film or thread-like material according to claim 2 around the carbon fiber string-like material, the film-like material or thread-like material is wrapped around a bobbin having a hollow shaft. Winding: While rotating the bobbin while feeding the string-like object through the hollow part of the shaft, the film-like object or thread-like object that is swung away from the bobbin is fed into the hollow shaft from the inlet of the string-like object and wound around the string-like object. A method for producing pellets used in the production of carbon fiber reinforced plastics. (6) When winding the thermoplastic resin or thermosetting resin film or thread-like material according to claim 2 around the carbon fiber string-like material, the film-like material or thread-like material is wrapped in one or more rows. 1. A method for producing pellets used in the production of carbon fiber reinforced plastics, comprising forming a tube by fusing or gluing the wires, and storing the string-like material in the hollow part of the tube. (7) When the thermoplastic resin or thermosetting resin film or thread-like material according to claim 2 is wound around the carbon fiber string-like material, the film-like material or thread-like material is wound around the string-like material. After that, both ends of the film-like material or filament-like material are twisted and fixed, and if necessary, the twisted parts are fused or bonded. (8) When winding the thermoplastic resin or thermosetting resin film or thread-like material according to claim 2 around a carbon fiber string-like material, the string-like material is fed through a die and wrapped around the die. The liquefied resin is discharged from the provided discharge hole, and the film-like material or thread-like material formed by solidifying the resin is given alternate twists and wound into a string-like material. A method for producing pellets used in the production of carbon fiber reinforced plastics, which is characterized by fixing objects by fusing them together. (9) The carbon fiber string-like material according to claims 2 to 8 is a carbon fiber string obtained by carbonizing the pitch fibers that are bundled by an air flow when they are collected on a porous belt by melt-blown spinning. 1. A method for producing pellets used for producing carbon fiber reinforced plastic, characterized in that the pellets are shaped like pellets. (10) The carbon fiber string-like material according to claims 1 to 9,
A carbon fiber-reinforced plastic characterized by being a sliver obtained by passing carbon fiber short fibers through a card, a fiber bundle obtained by drafting the sliver, a twisted product of the sliver, or a product obtained by twisting the fiber bundle. A method for producing pellets used in the production of. (11) A method for producing pellets used for producing carbon fiber reinforced plastics, wherein the pitch fibers according to claims 1 to 10 are produced from mesoface pitch.