JPH0641651B2 - Carbon fiber manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing carbon fibers using an organic polymer multifilament as a raw material for carbonization.

[Prior art]

2. Description of the Related Art Conventionally, it has been widely practiced to use an organic polymer filament such as an acrylonitrile polymer fiber (PAN) or a pitch fiber as a raw material for carbonization, and carbonize this to produce a carbon fiber. In this case, the organic polymer filament is once wound into a frame or roll in the form of multifilament. Then, the organic polymer multifilament wound on this frame or roll is, as it is or drawn from here, pretreatment for carbonization, for example, flameproofing treatment in the case of polyacrylonitrile fiber, in the case of pitch fiber After being subjected to the infusibilization treatment, it is sent to a carbonization treatment step, carbonized, and further heat-treated if necessary.

By the way, in the production of such a carbon fiber, as described above, the organic polymer filament is roll-transferred in the form of a multi-filament, and the frame or roll is wound onto or pulled out from the roll, During the winding and the drawing, it is moved in the vertical and horizontal directions by the traveling device. That is, the organic polymer filament undergoes surface friction in various directions before being made into carbon fiber. The surface friction causes inconveniences such as yarn breakage and damage to the filament surface, which deteriorates the quality of the carbon fiber produced.

〔Purpose〕

It is an object of the present invention to solve the above problems found in conventional carbon fiber production.

〔Constitution〕

According to the present invention, there is provided a method for producing a carbon fiber, which comprises using an organic polymer multifilament, which is converged and immobilized using poly (ethyloxazoline), as a raw material for carbonization.

The present invention is characterized by using, as a carbonization raw material, an organic polymer multifilament that is converged and immobilized using poly (ethyloxysazoline).

The poly (ethyloxazoline) used as the convergent fixing agent for the organic polymer multifilament in the present invention is 2-ethyl-2
-Obtained by ring-opening polymerization of oxazoline, having the formula It has a repeating structural unit represented by
Some 100,000 are known. According to the research conducted by the present inventors, when this poly (ethyloxazoline) is used as a convergent fixing agent for an organic polymer multifilament, the obtained convergent multifilament has excellent converging property and has a remarkable surface friction. It has been found to be reduced and very slippery, and the use of this as a raw material for carbonization overcomes the disadvantages found in the prior art.

The organic polymer filaments used in the present invention are conventionally known ones and include acrylonitrile polymer filaments, petroleum or coal pitch filaments, and the like. Such filaments are usually handled in the form of 1000 to 24000 multifilaments and transferred to each processing step as described above.

In the present invention, the convergent immobilization treatment for the multifilaments may be carried out at an appropriate point before the pretreatment step for carbonization, and for example, it is preferably carried out just before winding on a roll or a frame, but from the roll or the frame. It can also be done after withdrawal. This immobilization treatment is carried out by applying a poly (ethyloxazoline) solution to the multifilaments, and its application method includes, for example, a dipping method, a spray method, a roll method, etc., but preferably a roll method is adopted. To be done. As the solvent for poly (ethyloxazoline), water, methanol, methyl ethyl ketone, or the like is used, but usually water or a mixture of water and an organic solvent is used. Poly (ethyloxazoline) in solution
The concentration is 0.01 to 2.0% by weight, preferably 0.05 to 1.0% by weight. The amount of the polymer attached to the multifilament is usually 0.000 with respect to 100 parts by weight of the multifilament.
It is 5 to 0.1 parts by weight, preferably about 0.025 to 0.05 parts by weight. After applying the poly (ethyloxazoline) solution to this multifilament, air dry or 100-250 ℃
Forcible drying is performed to some extent to obtain a convergent immobilization product of multifilaments having a thin layer of poly (ethyloxazoline) on the surface.

When the convergent immobilization of multifilaments is performed using the poly (ethyloxazoline) solution according to the present invention, another polymer, for example, a soluble polymer such as polyvinyl alcohol can also be used in the solution.

The multifilament convergent immobilization product obtained as described above has a very good surface sliding property with significantly reduced surface friction, and the surface of the multifilament is protected from damage due to mechanical friction and at the time of its transfer. The yarn breakage due to friction is prevented. Further, the convergent immobilization of the multifilament according to the present invention is good, and the converged state is not destroyed during transfer, and can be handled in the same manner as a single fiber having good mechanical strength.

The multifilament convergent immobilization product according to the present invention can be subjected to pretreatment and then carbonization treatment into a carbon fiber by a conventional method. Such carbon fiber production technology itself is conventionally known. For example, in the case of producing carbon fibers from a multifilament convergent immobilization product of a polyacrylonitrile-based polymer, first, the multifilament is wound in a frame to about 230 in air. Oxidize by heating to about ℃. Next, remove the multifilament from the frame, heat and carbonize it in a vacuum furnace at about 1000 ° C, then leave it at about 1400 ° C.
Then, it is heated to about 2500 ° C. by an electric current in a carbon tube furnace in an argon stream. On the other hand, in the case of producing carbon fibers from a pitched multifilament convergent immobilization product, the multifilament is heated to a temperature of about 350 to 400 ° C in air to infusibilize it, and then treated in an inert gas. Carbonize by heating to about 1000 ° C.

The poly (ethyloxazoline) used as the multi-filament convergent immobilizing agent in the present invention has excellent heat resistance and does not cause perceptible decomposition up to about 380 ° C in air and about 400 ° C in an inert gas. Therefore, in the case of producing carbon fibers as described above, by performing the pretreatment step for carbonization at a temperature of 380 ° C. or less, there is an advantage that the multifilaments can be transferred to the carbonization step in the converged and fixed state. is there.

[Effect]

The organic polymer multifilament convergently fixed with poly (ethyloxazoline) used as the carbonization raw material in the present invention has good surface slipperiness with small surface friction as described above, and therefore roll transfer is possible. Easy and
It is easy to wind and draw on a frame or roll,
In addition, the surface is not damaged by the contact with the traveling device that moves the multifilament up, down, left, and right during the winding and drawing.

As described above, the poly (ethyloxazoline) according to the present invention
By using the organic polymer multifilament which is converged and immobilized by using, the multifilament can be handled very smoothly in the production of carbon fiber, and the production of carbon fiber can be carried out very efficiently. it can.

〔Example〕

 Next, the present invention will be described in more detail with reference to Examples.

Example A polyacrylonitrile-based polymer (PAN) multifilament (number: 3000) was immersed in a 0.05 wt% aqueous solution of poly (ethyloxazoline) (average molecular weight: about 100,000), and then dried by heating.

It was confirmed that the thus obtained multifilament convergent and immobilized product has a strong bonding force between the filaments and can be handled in the same manner as a single fiber. Further, when the slipperiness of the filament surface was compared with that of an untreated PAN filament, it was confirmed that the one according to the present invention had a smooth surface and had very good slipperiness.

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Claims (1)

[Claims] 1. A method for producing a carbon fiber, which comprises using an organic polymer multifilament, which is converged and immobilized using poly (ethyloxazoline), as a raw material for carbonization.