JPH075766B2 - Method for producing carbon fiber reinforced thermosetting resin - Google Patents

Description

The present invention relates to a method for producing a resin reinforced with carbon fibers.

Carbon fiber, which is lightweight, has heat resistance, chemical resistance, and has good mechanical properties, has been actively researched to reinforce thermosetting resins, and has already been used as a primary and secondary structural material for aircraft such as aircraft. It has been put to practical use as a part of sports equipment such as golf racks and tennis rackets and fishing gears.

On the other hand, research into producing carbon fiber from inexpensive raw materials has also become popular, and particularly in recent years, research into producing high-performance and high-elasticity carbon fiber with higher strength and elasticity than petroleum or coal-based tarpits, or even if the performance is not so high, is economical. Studies have been conducted to manufacture general-purpose carbon fibers that are general and versatile.

Carbon fibers obtained from pitches have various physical properties depending on the physical properties (isotropic or anisotropic) of the pitch for spinning, the method of solvent spinning, and the carbonization temperature of the pitch fiber, but especially by the method of solvent spinning. The form of carbon fiber is decided.

Generally, there are three types of melt fiberizing methods for pitch. Part 1
One is the same method as that for melt spinning such as polyester fiber and polypropylene fiber, but the melt is extruded into a multi-hole nozzle with an extruder, and this is drafted with a winder and continuously wound as fine yarn. Continuous spinning method "
Is. The carbon fibers produced in this way take the form of long filaments. Further, the first is a so-called "centrifugal fiberizing method" in which a molten pitch is fed to a high-speed rotating body having holes and the fibers are made into fine yarn by centrifugal force. The carbon fiber produced by this method has a limited length because it cannot be wound continuously, and takes a relatively long cotton-like form.

Further, one method is a so-called "vortex fiberizing method" in which a molten pitch is fed to a nozzle and, at the same time, a vortex gas is blown from the periphery and is entrained into fibers (for example, Japanese Patent Publication No.
See 58-57374). Since the carbon fiber produced by this method cannot be wound continuously, it has a limited length and also has a cotton-like shape.

The centrifugal fiberizing method and the vortex fiberizing method can produce only short carbon fibers, but the fiberizing process is economical, and is suitable for producing general-purpose carbon fibers.

Among the two methods, the eddy current fiberizing method has an advantage that it can be fiberized into a finer yarn and the fiberizing device is inexpensive, but has a drawback that only shorter pitch fibers can be obtained.

Furthermore, due to the characteristics of the method, the fibers obtained by the vortex method are deposited on the belt conveyor, continuously infusibilized and then carbonized, and the method of producing carbon fibers in the form of a bulky mat is the most technically and economically possible. It is also advantageous. However, as compared with the centrifugal fiberization method, only shorter fibers can be spun, so it is spun like carbon fiber made by the centrifugal fiberization method into one tow, cut into chops, or braided. The post-carbonization process is technically difficult. Therefore, it is difficult to obtain a carbon fiber chip that is usually used for fiber-reinforced thermoplastics.

The present inventors have arrived at the present invention as a result of earnestly investigating a method in which cottony carbon fibers can be used without post-processing while paying attention to the superiority of the vortex fiberizing method. That is, the present invention relates to, for example, the method described in Japanese Patent Publication No. 58-57374 (at least three pipes that are in a viscous state are discharged from an outflow orifice and are circumferentially spaced around the orifice). A high-speed gas stream is linearly blown out from the gas jet nozzle, wherein each of the gas streams is first directed toward the outflow direction of the substance and the tangential component along the outer periphery of the cross section that crosses the central axis of the substance. A component that gradually approaches the central axis of the substance and then gradually separates from the central axis, whereby the outflow of the pitch in the viscous state rotates about the central axis. It gradually becomes thinner, becomes fibrous, and is ejected in a spiral shape.
The so-called vortex fiberizing method that stretches and fiberizes)
The infusible and carbonized Pitch fibers that have been made fibrous and deposited by the method are impregnated with a thermosetting resin into a bulky carbon fiber mat with a density of 0.008 to 0.08 g / cm ³ to form a sheet, and then molded. Provided is a method for producing a carbon fiber reinforced thermosetting resin characterized by being processed. In the swirl method, high pressure air, high pressure steam, gas combustion waste gas, etc. are used as the hot gas flow.

Pitch fibers made into fibers by the vortex method usually have a length of 5 mm to 50 cm,
It has a diameter of 4 to 20 μm and is deposited on a mesh belt conveyor, for example. The deposition density and amount can be controlled by changing the conveyor speed and the fiberization speed. In order to continuously infusibilize and carbonize, the deposition density must be a bulky deposit so that air and nitrogen gas can sufficiently flow therethrough. On the other hand, considering the efficiency of the furnace, it is preferable that the density is high. Therefore, the density of the carbon fiber mat is preferably 0.008 to 0.08 g / cm ³ . After the carbonization, the bulky carbon fiber mat is optionally surface-treated and then sized. Such mats are generally stored in rolls, or they are continuously fed from a carbonization furnace to an impregnator, optionally dried and stored as a sheet for winding. Since the carbon fiber mat according to the present invention is two-dimensionally accumulated in a plane, even if it is compressed from the direction perpendicular to the mat plane, there is little breakage damage of the yarn, and compression up to 1/15 is possible. The compression may be carried out before or after the mat is impregnated with the resin, but the post-impregnation compression is preferred in which the resin-impregnated sheet-like body which does not cause loss of yarn and facilitates the compression operation is compressed. A pressure roll is preferable for the compression operation.

The step of impregnating the mat of the present invention with a resin can be continuously carried out by an impregnating apparatus equipped with a feed roll, a squeezing roll, a dryer, an impregnation bath, a winding roll and the like when the mat has a sufficient breaking strength. If the breaking strength is insufficient, it can be placed on a carrier film such as a plastic and the like with a similar device. In addition, as the method of impregnation, in addition to the method of immersing in a solution, there are a method of spraying a necessary amount from above, a method of attaching from a kiss ring roll, and the like.

The thermosetting resin referred to in the present invention may be any resin as long as it becomes a solid having self-supporting property when heated in the presence or absence of a cross-linking agent, but generally, epoxy resin, polyester resin, vinyl There are ester resins, phenol resins, polyimide resins or mixtures thereof. A crosslinking agent, a viscosity modifier, or a reinforcing material other than carbon fiber can be blended in this resin. These thermosetting resins can be attached to the carbon fiber mat as it is or as a solvent solution. In general, the sheet-shaped body to which the resin is attached is stored in a semi-cured state (B stage), the sheet is cut out at the time of molding, and, of course, many sheets are stacked and processed. still,
The mixing ratio of thermosetting resin and carbon fiber is 0 for carbon fiber.
It is preferably blended so as to be 5 to 60% by weight.

The carbon fiber referred to in the present invention is obtained from pitch as a raw material regardless of whether it is petroleum-based or coal-based, isotropic or anisotropic. The carbonization temperature can be changed from 800 ° C to 2800 ° C, resulting in
Both carbon fibers and graphitized fibers are useful in the present invention.

The sheet-like body of the present invention includes pressure molding, hand layup,
It becomes the molded body required by molding methods such as winding.

Carbon fiber in the molded body serves as a reinforcing material for mechanical properties, but since the mat of the present invention is an amorphous type, rather than crosswise prepreg, unidirectional prepreg, rather than unidirectional strengthening.
It is effective for strengthening in all directions on a plane like a sheet molding compound.

Further, the present invention can improve the electric conductivity and sliding characteristics of the molded body. In particular, since the fibers are longer than the chopped and milled carbon fibers, the electric conduction effect is remarkable, and it can be used as an electromagnetic shielding material.

Next, the present invention will be specifically described with reference to examples. Parts mean parts by weight.

Example 1 An isotropic pitch obtained by adjusting a coal tar pitch was vortexed into fibers by the method of Japanese Patent Publication No. 58-57374 (using high pressure air), and then deposited on a belt conveyor to continuously make it infusible. Then, it was carbonized at 1000 ° C. to obtain a bulky mat having a height of 42 mm and a width of 300 mm. The density was 0.02 g / cm ³ , the carbon fiber length was 80 mm, the longest length was 120 mm, the shortest length was 50 mm, and the carbon fiber yarn diameter was 7 to 9 μm. The tensile strength of the yarn is 80 kg / mm ² , and the tensile modulus is
It was 4 Ton / mm ² .

This mat is cut into 300 (length) × 300 (width) × 42 (height) mm, and epoxy resin (Epiclon 850: Dainippon Ink) 100
Part, 90 parts of methylnaphthic acid anhydride, 4 parts of chlorophenylated urea and 146 parts of acetone were impregnated into this and then squeezed to 1/5. After a day's breeze, dry at 110 ° C for 8 minutes,
I got a paper-like sheet. This sheet at 20kg / mm ² pressure
It was pressure molded at 150 ° C for 60 minutes to make a plate of about 2 m / m. The carbon fiber content was about 20% by weight. The bending strength of this molded plate according to JIS-K-6911 was 15.8 kg / mm ² .

Example 2 The bulky carbon fiber mat of Example 1 was used, with a length of 300 mm and a width of 300 m.
It was cut into m and height of 42 mm, which was impregnated with a resin solution consisting of epoxy resin [Epiclon 850 (Dainippon Ink)] 100 parts, nadic acid anhydride 90 parts, chlorophenyl urea 4 parts, acetone 129 parts, and then squeezed to 1/15. . After air-drying for one day, it was dried at 110 ° C for 8 minutes to obtain a sheet. This sheet 2
It was pressure-molded at 0 ° C./mm ² pressure at 150 ° C. for 60 minutes to make a plate of about 2 m / m. The carbon fiber content was about 60% by weight. JIS-K
The bending strength of the molded plate according to −6911 was 28.2 kg / mm ² .

Example 3 The mat of Example 1 was cut into a length of 300 mm, a width of 300 mm, and a height of 42 mm, and 100 parts of a vinyl ester resin [Decklite 5210 (Dainippon Ink)] diisocyanate [Millionate MR400 (Nippon Polyurethane)] 10 parts After impregnating with a resin solution consisting of 1 part of catalyst (benzoyl peroxide) and 17 parts of acetone, the solution was squeezed to 1/15. After air-drying for one day, it was dried at 110 ° C for 8 minutes to obtain a sheet. 1 at 80kg / mm ² pressure
It was pressure molded at 30 ° C for 10 minutes to make a plate of about 2 m / m. The carbon fiber content was about 40% by weight. The bending strength of this molded plate according to JIS-K-6911 was 18.2 kg / mm ² .

Example 4 The mat of Example 1 was cut into a length of 300 mm, a width of 300 mm, and a height of 42 mm, and this was impregnated with a resin solution consisting of 100 parts of phenol resin [Priofen 5900 (Dainippon Ink)] and 20 parts of acetone, After air-drying for one day, it was dried at 110 ° C. for 10 minutes to obtain a paper-like sheet. 20kg of this sheet
/ mm ² pressure and pressure molding at 150 ° C. for 60 minutes to make a plate of about 2 m / m. The carbon fiber content was about 35% by weight. JIS-
The bending strength of this molded product according to K-6911 was 28.2 kg / mm ² .

Example 5 Anisotropic pitch obtained by adjusting coal tar pitch was vortex fiberized in the same manner as in Example 1 and then deposited on a belt conveyor, continuously infusibilized, and subsequently carbonized at 1300 ° C. , A bulky mat with a height of 40 mm and a width of 300 mm was obtained. Specific gravity is 0.03g / c
The center of m ³ and the length of the carbon fiber was 40 mm, the maximum length was 60 mm, the minimum length was 20 mm, and the diameter of the carbon fiber was 7 to 9 μm. The tensile strength of the thread is 22
The tensile elastic modulus was 0 kg / mm ² and 4 Ton / mm ² . This mat was compressed to 1/3 by a pressure roll, impregnated with a resin solution consisting of 100 parts of phenol resin [Priofen 5900 (Dainippon Ink)] and 20 parts of acetone, and further squeezed to 1/3. After air-drying for one day, it was dried at 110 ° C for 12 minutes to obtain a paper-like sheet. This sheet was pressure molded at 150 ° C. for 60 minutes at a pressure of 20 kg / cm ² to give a plate of about 2 m / m. The carbon fiber content was about 40% by weight. The bending strength of this molded product according to JIS-K-6911 was 28.2 kg / mm ² .

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location D01F 9/14 7199-3B D04H 1/42 E 7199-3B 1/58 Z 7199-3B // B29C 70/10 (72) Inventor Yuji Matsumura 2-17-611 Rokugen-cho, Nishinomiya-shi, Hyogo Prefecture (72) Inventor Keihachiro Tanaka 4-32-11 Kasugaoka, Itami-shi, Hyogo Prefecture

Claims (1)

[Claims] 1. A viscous pitch is discharged from an outflow orifice, and a high-speed hot gas stream is linearly blown out from at least three gas ejection nozzles arranged at intervals in the circumferential direction around the orifice. , Where each of the gas streams gradually approaches the central axis of the pitch and then gradually approaches the central axis of the pitch in the direction of the tangential component along the outer periphery of the cross-section crossing the central axis of the pitch and the outflow direction of the pitch. It has a component that gradually separates from the axis, whereby the outflow of the pitch in the viscous state gradually turns around the central axis while gradually thinning, becoming fibrous, and jumping out in a spiral shape. Is melted, stretched and fiberized, infusibilized Pitch fibers deposited by the so-called vortex method,
A bulky carbon fiber mat with a density of 0.008 to 0.08 g / cm ³ formed by carbonization is impregnated with a thermosetting resin to form a sheet,
A method for producing a carbon fiber reinforced thermosetting resin, which is characterized by molding.