JPS62263231A - Production of carbon fiber-reinforced thermosetting resin - Google Patents

Abstract

PURPOSE:To obtain the titled resin improved in electrical conductance and sliding characteristics, suitable as an electromagnetic shielding material, by impregnating a thermosetting resin in a carbon fiber mat prepared by making pitch fiber formed through a spiral flow process infusible followed by carbonization. CONSTITUTION:First, a viscous pitch is delivered through olifice, while blowing high-speed hot gas flow linearly through three or more jet nozzles located at an internal in the circumferential direction around said olifice, to make the pitch into fibrous and spiral form followed by drawing to convert to fiber. The resulting pitch fiber is made infusible followed by carbonization to make a bulky carbon fiber mat with a density 0.008-0.08g/cm<3>. This mat is impregnated with such an amount of thermosetting resin (e.g. epoxy resin) that the resulting content of the carbon fiber falls between 0.5-60wt% to make a sheet. This sheet is then subjected to forming process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing carbon N & male reinforced resins.

Carbon fiber, which is lightweight, has good heat resistance, chemical resistance, and mechanical properties, is being actively researched to reinforce thermosetting resins, and is already being used as a primary and secondary structural material for aircraft and other flying objects. It has also been put into practical use as a component of sports equipment such as tennis rackets, fishing rods, and golf shafts.

On the other hand, research into producing carbon fiber from inexpensive raw materials has become active, particularly in recent years, and research into producing high-performance carbon and fibers with higher strength and higher elasticity than petroleum or coal-based tar pitch has become active.
Alternatively, research is being conducted to produce general-purpose carbon-containing wheat fiber that is economical and versatile, even if it does not have the performance of food.

Carbon fiber obtained from pitch is based on the physical properties of pitch for spinning (
Although the physical properties vary depending on the pitch fiber carbonization temperature (isotropy, anisotropy), melt spinning method, and pitch fiber carbonization temperature, the form of the carbon fiber is determined by the melt spinning method in particular.

Generally, there are three types of pitch melt-fiberization methods.

One method is similar to melt spinning for polyester fibers and polypropylene fibers, but an extruder extrudes the melt into a multi-hole nozzle, and a winder drafts it and continuously winds it as a fine thread. This is the ``continuous spinning method''. Carbon fibers produced in this way take the form of long filaments. Another method is the so-called "centrifugal fiberization method," in which molten pitch is fed to a high-speed rotary body with bored holes and is fiberized into fine threads by centrifugal force. Carbon fibers produced by this method cannot be continuously wound, so there is a limit to their length, and they take the form of relatively long fluff.

Another method is the so-called "vortex fiberization method" in which molten pitch is fed into a nozzle and at the same time vortex gas is blown from the periphery to form fibers (for example, see Japanese Patent Publication No. 58-57374).

Carbon fibers produced by this method cannot be wound continuously, so there is a limit to their length, or they take a fluffy form.

Although the centrifugal fiberization method and the vortex fiberization method can only produce short carbon fibers, the fiberization process is economical, so they are suitable for producing general-purpose carbon fibers.

Of the two methods, the vortex fiberization method has the advantage of being able to fiberize into thinner threads and the fiberization equipment is inexpensive, but it has the disadvantage that it can only produce very short pitch fibers.

Furthermore, due to the characteristics of the method, the fibers obtained by the eddy current method are deposited on a belt conveyor, continuously infusible, and then carbonized, forming a bulky mat-like carbon fiber. The nature produced into J, m is the most technically and economically advantageous.

However, compared to the centrifugal fRa method, only shorter fibers can be spun, so carbon fibers made by the centrifugal fiberization method are spun into a single tow, cut into chops, and then cut into a single tow. The post-carbonization process that involves knitting is technically difficult. Therefore, it is difficult to obtain carbon fiber chops such as those normally used in fiber-reinforced thermoplastics.

The present inventors focused on the superiority of the eddy current fiberization method, and as a result of intensive study on a method that can utilize cotton-like carbon fibers without post-processing, they arrived at the present invention. That is, the present invention relates to the method described in, for example, Japanese Patent Publication No. 58-57374 (in which pitch in a viscous state is caused to flow out from an outflow orifice, and at least three pipes are arranged around the orifice at intervals in the circumferential direction). A high-speed gas stream is blown out in a straight line from a gas jet nozzle, and each of the gas streams has a tangential component along the outer periphery of a cross section that crosses the central axis of the substance, and a component in the tangential direction along the outer circumference of the cross section that crosses the central axis of the substance, and a component in the tangential direction along the outer circumference of the cross section that intersects the central axis of the substance, and a component in the tangential direction along the outer circumference of the cross section that crosses the central axis of the substance, and and a component that gradually approaches the central axis of the substance and then gradually moves away from the central axis, so that the outflow flow of the pitch in the viscous state rotates around the central axis. The pitch fibers are gradually thinned, made into fibers, spun out in a spiral, and stretched to make them into fibers. o, oos~0.08r/cm'
Provided is a method for producing a carbon fiber-reinforced thermosetting resin, which comprises impregnating a bulky carbon fiber mat with a thermosetting resin to form a sheet, followed by molding. In the eddy current method, high pressure air, high pressure steam, gas combustion waste gas, etc. are used as the hot gas flow.

Pitch fibers made by the eddy current method usually have a length of 5u to 50c.
Ms has a diameter of 4 to 20 μm and is deposited, for example, on a mesh belt conveyor. The deposition density and amount can be controlled by changing the speed of the conveyor and the speed of fiberization. In order to continue to infusible and carbonize, the deposit needs to be bulky enough to allow sufficient air and nitrogen gas flow. on the other hand,
Considering the efficiency of the furnace, higher density is preferable, so carbon fiber mat has a density of 0.008 to 0.08 p/crI.
L" is preferred. This bulky carbon fiber mat is optionally surface treated and sized after carbonization. Such mats are generally stored in rolls or continuously removed from a carbonization furnace. The carbon fiber mat is fed to an impregnation machine, dried continuously in some cases, and then rolled up and stored as a sheet.The carbon fiber mat of the present invention is deposited two-dimensionally on a flat surface, so it is compressed from the perpendicular direction of the mat plane. Even if the mat is impregnated with resin, there is little damage from yarn breakage, and compression can be performed up to the 4th position.Compaction can be done before or after impregnating the mat with resin, but it is better to impregnate the mat with resin, which makes the compression operation easier without loss of yarn. It is preferable to use impregnated compressed cotton, which compresses the sheet-like material.The compression operation is preferably performed using a pressure roll.

The process of impregnating the mat of the present invention with resin can be carried out continuously using an impregnating device equipped with a feed roll, a squeezing roll, a dryer, an impregnating bath, a winding roll, etc., if the mat has sufficient breaking strength. .

Only if the breaking strength is insufficient can it be carried out using a similar device by placing it on a carrier film such as plastic.

In addition, as for impregnation methods, there are methods such as immersing in a solution, spraying the required amount from above, and applying from a kiss ring roll.

The thermosetting resin used in the present invention may be any resin that becomes a self-supporting solid when heated in the presence or absence of a crosslinking agent, but generally includes epoxy resin, polyester resin, vinyl resin, etc. These include ester resins, phenolic resins, polyimide resins, or mixtures thereof. A crosslinking agent, a viscosity modifier, or a reinforcing material other than carbon fibers can be blended into this resin. These thermosetting resins are
However, it can also be applied to such carbon fiber mats as a solvent solution. Generally, a sheet-like body with resin attached is stored in a semi-cured state (B stage), and the sheet is cut out at the time of molding, and of course, many sheets are stacked and processed. still,
The blending ratio of thermosetting resin and carbon fiber is 0 for carbon fiber.
．． The carbon fiber referred to in the present invention, which is preferably blended in an amount of 5 to 60% by weight, may be petroleum-based or coal-based.
Moreover, it can be obtained using pitch as a raw material, regardless of whether it is isotropic or anisotropic. The carbonization temperature can vary from 800°C to 2800°C, so that both carbon fibers and graphitized fibers are useful in the present invention.

The sheet-like body of the present invention can be produced by pressure molding, hand lay-up,
It becomes a molded body required for molding methods such as winding.

Carbon fiber serves as a reinforcing material for mechanical properties in the molded body, but since the mat of the present invention is amorphous, it is not reinforced in a fixed direction as in cross prepreg or unidirectional prepreg.
Effective for reinforcing flat surfaces in all directions, such as sheet molding compounds.

Further, the present invention can also improve the electrical conductivity and sliding characteristics of the molded body. In particular, since it has longer fibers than chopped or milled carbon fibers, it has a remarkable electrical conductivity effect and can be used as an electromagnetic shielding material.

Next, the present invention will be specifically explained using examples. Parts mean parts by weight.

Example 1 The isotropic pitch obtained by adjusting the coal tar pitch was made into vortex fibers by the method of Japanese Patent Publication No. 58-57374 (using high-pressure air), deposited on a belt conveyor, continuously infusible, and then Carbonized at 1000℃, height 42cm 1 width 300cm
A bulky mat of ma+ was obtained. The density is 0.02 t/
CR! L", the carbon fiber length is mainly 80mm and the longest is 120mm.
The yarn diameter of the 1u1 carbon fiber and the shortest 50u1 carbon fiber was 7 to 9 μm. Further, the tensile strength of the yarn was 80 kg7m'', and the tensile modulus was 4 Ton/XI''.

This mat was cut into 300 (vertical) x 300 (width) x 42 (height) u, 100 parts of epoxy resin (Epicron 850: Dainippon Ink), 90 parts of methylnadic anhydride, 4 parts of chlorphenylated urea, and 146 parts of acetone. After impregnating this with a resin solution consisting of 1.5 parts, it was squeezed to 1. -After the Japanese wind turn, 11
It was dried at 0°C for 8 minutes to obtain a paper-like sheet. This sheet was pressure-molded at 150°C for 60 minutes using a 20 to 9 cm inch mold to form a plate with a thickness of approximately 2 m/m.The content of carbon fiber was as follows:
It was about 20i1i-%. The bending strength of this molded plate according to JIS-6911 is 15.8 k (il /
It was U”.

Example 2 The bulky carbon fiber mat of Example 1 was
001 Ij, cut to a height of 42 m+, and use epoxy resin [Epicron 850 (Dainippon Ink) 1 100 parts nadic anhydride 90 parts chlorphenylurea 4 parts acetone
After impregnation with a resin solution consisting of 129 parts ≦5
I narrowed it down to. - After drying in the sun, it was dried at 110° C. for 8 minutes to obtain a sheet.

This sheet was heated to 20' to 97cm'' at 150℃ for 60 minutes.
It was press-molded into a plate with a thickness of about 2 m/m. The carbon fiber content was approximately 60% by weight. The bending strength of this molded plate according to JIS-6911 was 28.2 to 9/2.

Example 3 The mat of Example 1 was cut into pieces of 300 m long, 30 mm wide, and 42 Ul high. )] 110
After impregnation with a resin solution consisting of 1 part benzoyl peroxide, 1 part acetone, and 17 parts, the resin solution was reduced to 1/5. - After sun drying, 110℃ x 8
A sheet was obtained by drying for several minutes.

It was press-molded at 130℃XIO minutes at 80 to 9/cIIL'' pressure to form a plate of about 2 m/m.The carbon fiber contains groups of about 4
It was 01i'Ek%. The bending strength of this molded plate according to JIS-6911 was 18.2 kg/msr''.

Example 4 The mat of Example 1 was cut to a length of 300 fIJ1, width of 300 mm, and height of 42 W, and this was impregnated with a resin solution consisting of 1100 parts of phenolic resin [Pryophen 5900 (Inu Nippon Ink)] and 20 parts of acetone. - After drying in the sun, it was dried for 110° C.×10 minutes to obtain a paper-like sheet.

This sheet was pressure-molded at 150° C. for 60 minutes at 20×9/2 pressure to form a plate of about 2 m/m. The carbon fiber content was approximately 35% by weight. JIS-ni-69
The bending strength of this molded product according to 11 is 28゜2kg/II
It was jt.

Example 5 The anisotropic pitch obtained by adjusting the coal tar pitch was turned into vortex fibers in the same manner as in Example 1, deposited on a belt conveyor, continuously infusible, and then carbonized at 1300°C. A bulky mat with a height of 40131% and a width of 300su was obtained. Is the specific gravity 0.03? /an”, carbon fiber length is 40m
The maximum power is 60w, the shortest power is 20+u+, carbon #! II!
The diameter of the fibers was 7 to 9 μm.

The tensile strength of the thread is 9/ILa at 220'! , the tensile modulus was 4TOnΔi. This mat was compressed to a μ size using a pressure roll, impregnated with a resin solution consisting of 1100 parts of a phenolic resin [Priophen 5900 (Dainippon Ink)] and 20 parts of acetone, and further compressed to a μ size.

- After drying in the sun, it was dried at 110°C for 12 minutes to obtain a paper-like sheet. This seat costs 20 kg/crn!
Pressure molded at 150°C for 60 minutes, approximately 2 m /
I made it to a board of m. The carbon fiber content was approximately 40% by weight. The bending strength of this molded product according to JIS-6911 was 28.2 kg/y''.

Patent applicant Dainippon Ink & Chemicals Co., Ltd. Osaka Gas Co., Ltd.

Claims (1)

[Claims] The pitch in a viscous state is caused to flow out of an outflow orifice, and a high velocity stream of hot gas is blown out in a straight line from at least three gas ejection nozzles circumferentially spaced around said orifice, wherein said gas is Each of the flows has a tangential component along the outer periphery of a cross section transverse to the central axis of the pitch, and a component in the outflow direction of the pitch that first gradually approaches the central axis of the pitch and then gradually moves away from the central axis. As a result, the pitch outflow flow in the viscous state gradually narrows while rotating around the central axis, becomes fibrous, is spun out in a spiral, and is stretched. A thermosetting resin is added to a bulky carbon fiber mat with a density of 0.008 to 0.08 g/cm^3, which is made by infusible and carbonized pitch fibers that have been fiberized and deposited using the so-called vortex method. A method for producing a carbon fiber-reinforced thermosetting resin, which comprises impregnating the resin into a sheet, and then molding the resin.