JPS602407B2 - Continuous production method of carbon fiber - Google Patents

Description

[Detailed description of the invention] The present invention relates to a continuous method for producing carbon fibers.

Carbon fiber is an organic polymer fiber such as polyacrylonitrile (
200-260 in an atmosphere containing oxygen (raw material fiber)
It is manufactured by heating to about qo to perform flameproofing treatment, and then heating to about 1000 to 1500°C in an oxygen-free atmosphere to perform carbonization treatment. When manufacturing carbon fiber continuously for a long time, it is necessary to tie the tail end of the raw material fiber wound on one bobbin to the head end of the raw material fiber wound on another bobbin. It won't happen.

Also, raw fibers and cut pieces must be tied together. That is, it becomes necessary to join the ends of the organic polymer fibers together. By the way, in the process of flame-retardant treatment mentioned above, the raw material fibers undergo oxidation and generate heat, but the fiber east is tightly compressed at the knots of the raw material fibers, making it difficult to dissipate the reaction heat, so heat accumulates. As a result, a more severe oxidation reaction takes place and the knot becomes even hotter, eventually causing the fibers to fuse and break. Conventionally, in order to prevent such troubles, Tokukan Sho 49-11 Suji No. 29 discloses a technique for wrapping a covering yarn in a spiral around the fibers when joining fiber bundles, and Hakama Seki Sho 50-15232. The publication discloses a technique of wrapping a metal thread around the cut portion or knot of the raw material fiber.

However, these techniques require considerably complicated work, and there are doubts about their applicability.Moreover, the latter technique involves flame-retardant treatment in a special atmosphere, such as a halogen gas atmosphere, and the metal threads are oxidized and cut, resulting in raw material fibers. Even the objective of continuously passing through a heating furnace may not be achieved. As a result of intensive research into a simple method for joining raw material fibers that does not require complicated operations as in the above-mentioned conventional technology, the present inventor has discovered that carbon fibers or organic polymers that have already been flame-retardant can be used without directly joining raw material fibers together. It has been found that if the fibers are joined indirectly through the fibers, the heat of reaction is well dissipated, and the raw fibers at the joint do not break due to stranding, and have thus come up with the present invention.

That is, the present invention is a method for producing carbon fibers, which is characterized in that the weave portions of two raw material fibers are indirectly joined via carbon fibers or organic polymer fibers that have already been flame-resistant treated to make them flame-resistant.

The present invention will be explained in detail below.

The organic polymer fibers used in the present invention include polyacrylonitrile fibers, cellulose fibers, polyamide fibers, pitch fibers, etc., but are not particularly limited thereto. In the present invention, carbon fibers or organic polymer fibers that have already been flame-resistant treated (hereinafter abbreviated as carbon fibers, etc.) to be interposed between two bundles of raw material fibers reliably connect the two bundles of raw material fibers. At the same time, it serves to prevent the fusion and breakage at knots as seen in the past.

That is, as shown in the drawing, the carbon fiber east 2 is interposed between the raw fiber east 1 and 1', and the end of the raw fiber east 1 and one end of the carbon fiber east 2 are connected, and the end of the raw fiber east 1' is connected to the end of the raw fiber east 1'. If the carbon fiber East 2 is connected to the pond end, the raw fiber East 1 and 1' will be indirectly connected, and since the carbon fiber East 2 does not generate as much reaction heat as the raw material fiber during flameproofing treatment, the raw material fiber East 1 and 1' will be indirectly connected. No heat of reaction accumulates in the knot formed between the fibers 1, 1' and the carbon fiber 2, and therefore this knot is not fused or broken. The same applies to the case where an organic polymer fiber which has already been subjected to flame-retardant treatment is used in place of the carbon fiber. These carbon fibers and the like need not be particularly limited as long as they can withstand the heat shrinkage force generated in the raw material fibers during flame-retardant treatment. Organic polymer woven ropes that have already been flame-retardantly treated, such as carbon fibers, do not necessarily have to have undergone sufficient flame-retardant treatment, and in some cases may have undergone insufficient flame-retardant treatment. , those that have undergone sufficient flame-retardant treatment are preferable because they generate less heat. When carrying out the manufacturing method of the present invention, carbon fibers or the like are joined between both cut ends of the raw material fiber or between the tail of the raw material fiber of one bobbin and the head of the raw material fiber of another bobbin,
Next, it is introduced into a heating furnace and subjected to flameproofing treatment.

Therefore, the method of the present invention is extremely simple, and even if the raw fiber is cut during flameproofing treatment, the method of the present invention can be applied immediately as long as it is outside the heating furnace, so the device can be operated continuously without stopping. can be ensured.

The present invention will be explained in more detail below using Examples and Comparative Examples.

Comparative example 450 plates/300 capes of polyacrylonitrile fiber 5k
After tying together both ends of the cut fibers that occurred on the outer surface of the g-wound bobbin, the fibers were passed into a heating furnace in an air atmosphere with a maximum temperature of 25 pi○ at a fiber running speed of 25 skins/min.
This fiber was cut at the above-mentioned knot midway through the furnace.

Example 1 The polyacrylonitrile fiber of the above comparative example was applied to both cut ends of the fiber of the above comparative example in advance in the heating furnace of the same comparative example for 25 times a day.
When the raw fibers were indirectly connected by tying both ends of a 1-length fiber that had been flame-retardantly treated at min. Ta.

Example 2 In place of the one-length fiber that had been flame-resistant treated in advance in Example 1, this fiber was further heated to a maximum temperature of 1400 pm.
Example 1 was carried out in exactly the same manner as in Example 1 except that a length of carbon fiber obtained by carbonization in a hydrogen chloride atmosphere was used, and the knot was not cut.

As is clear from the above detailed explanation, the manufacturing method of the present invention involves joining two bundles of raw material fibers to perform flame-retardant treatment. Since they are bonded, heat dissipation at the bonded portion is good, and therefore flame-retardant treatment can be performed without causing the fusion breakage at knots that has conventionally been seen.

In addition, the manufacturing method of the present invention is an extremely simple method that only involves joining the raw material fibers through carbon fibers, etc., so even if the raw material fibers are cut during the flameproofing treatment, if they are outside the heating furnace, they can be immediately repaired. The method of the invention can therefore be carried out, thus ensuring continuous operation at all times without stopping the device. ``The simple illustration of the drawing shows an example of indirect bonding of raw fibers in the method of the present invention.

1,1'...Raw fiber, 2...Carbon fiber East.

Claims (1)

[Claims] 1. A method for continuously producing carbon fibers from organic polymer fibers, characterized in that the ends of the organic polymer fibers are indirectly joined together via carbon fibers or flame-retardant fibers to make them flame-retardant. Continuous continuous production method of carbon fiber.