JPS63264918A - Production of carbon fiber - Google Patents

Abstract

PURPOSE:To obtain a carbon fiber capable of preventing napping and surface damaging and simultaneously opening sticking, by preapplying a given amount of a bundling oiling agent to a flameproofed fiber bundle, drying the fiber bundle, feeding the dried fiber bundle to a carbonization furnace and heat- treating the fiber bundle. CONSTITUTION:An acrylonitrile based fiber bundle is flameproofed in an oxidizing atmosphere and an aqueous solution of polyethylene oxide, methyl etherified, ethyl etherified or hydroxyethyl etherified cellulose or/and polyvinyl methyl ether having >=100,000 molecular weight is applied to the flameproofed fiber bundle so as to provide 0.01-0.5wt.% pickup by using a spray or roller, etc. The resultant fiber bundle is then dried at <=250 deg.C temperature, subsequently introduced into a carbonization furnace and continuously heat-treated to afford the aimed fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION In the continuous production of acrylic [J nitrile carbon fibers], a specific amount of a specific chemical substance is attached to a flame-resistant fiber bundle to improve the cohesiveness of the fiber bundle. The present invention relates to a method for producing high-performance carbon fibers by preventing fluff, defibrating agglutination, and preventing surface damage. More specifically, the present invention reduces the fluff and fiber waste that accumulates in the carbonization furnace, prevents narrowing of the yarn path, suppresses the generation of fluff on the fiber bundles passing through, and improves the guide to the furnace. It prevents fluffing and wrapping on rollers, and also defibrates layer adhesion caused in the flame-retardant process, and prevents surface damage to flame-retardant fibers and carbon fibers caused when passing through roller guides, resulting in a high C. This is a method of manufacturing carbon fiber with high performance.

Generally, to produce carbon fibers, acrylonitrile fiber bundles are made flame resistant in an oxidizing atmosphere of about 260° C. to obtain flame-resistant fibers, and then carbonized in an inert atmosphere of about 1300° C. to obtain carbon fibers.

A number of technical problems arise when such manufacturing methods are operated continuously. That is, (1) fluff and fiber waste accumulates in the furnace during carbonization, and the yarn path in the furnace is narrowed by the deposits, which causes fluff on the passing fiber bundles, and also causes damage to the passing rollers. The guide also makes the fiber bundle fluffy.
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■Flame-resistant production of flame-resistant fibers from acrylonitrile fibers■
In culms, n-wearing of fiber M@shi is unavoidable to some extent, but n
If the degree of decomposition is large, the strength of the carbon fiber obtained by carbonization will decrease unless defibration is performed, and high-performance carbon fiber will not be obtained. ■When heat-treating flame-resistant cloth in a carbonization furnace, especially in a two-stage carbonization furnace, to make it coarse with carbon, the fibers are processed by a large number of rollers,
The carbon fiber must pass through the presser roller guide, and at this time some degree of surface loss IB is usually unavoidable, but if there is one surface loss, the strength of the carbon fiber will decrease accordingly, and high-performance carbon fiber will not be obtained. .

The present invention solves all of these problems in the production of charcoal #i fiber at once, and makes it possible to obtain high-quality, high-performance carbon fibers.

Specifically, the present invention is as follows.

Flame-resistant fiber bundles are supplied to a carbonization furnace and continuously heat-treated to produce acrylonitrile-based charcoal*m navy blue. lH
An aqueous solution of polyethylene oquinide with a molecular weight of 100,000 or more, methyl etherified, ]-deletherized or hydroxyethyl etherified hirulose, or polyvinyl methyl ether is applied to the bundle in advance, and the adhesion occurs. Adjust the amount from 0.01 to 0. s! A method for producing carbon fibers, which comprises drying at a temperature of 250° C. or lower, followed by the heat treatment.

According to the present invention, deposits in a carbonization furnace can be significantly reduced, and fluff of the obtained carbon fibers can be significantly reduced. In addition, by defibrating the flame-resistant fibers that stick together during the flame-retardant process, high-strength carbon fibers with less adhesion can be obtained.
High-strength carbon fiber can be obtained by preventing surface damage.

In the present invention, the flame-resistant fiber bundle of the 4JA#i bundle to be treated is separated by 1q from the acrylonitrile fiber bundle. Acrylonitrile-based fibers include at least 9018i% of 7-acrylonitrile components in their polymer components, and have co-! It is a fiber made of a polymer or copolymer that usually contains 0 to 10% by weight of acrylonitrile and a vinyl compound for copolymerization as a fi-coating component.

The 111rN bundle is usually composed of 100 to 30,000 filaments with a single fiber fineness of 0.5 to 1.5 deniers.

Chemical substances (
The sizing agent (hereinafter referred to as "sizing agent") is polyethylene oxide (PEO) with a molecular fi of 100,000 or more, and G? Preferably, the molecular weight is 100,000 to 4.8 million, particularly preferably 100,000 to 110.
It is a PEO of 10,000. When the molecular weight is less than 100,000, the viscosity is low and effects such as prevention of fuzz cannot be sufficiently obtained. P E O
In the case of , if the molecular weight exceeds 1.1 million, the viscosity tends to increase at low concentrations. In this case, acetone, methanol, ethanol, etc. can also be added.

Other sizing agents include methyl-etherified, ethyl-etherified or hydroxyethyl-etherified cellulose, such as methylcellulose, ethylcellulose, human kilooxymethylcellulose, and hydroxyethylpyrus. Another sizing agent is polyvinylmethyl needle 1.

The above-mentioned sizing agents can be used alone or in combination of two or more.

These bundles ~j are made to adhere to the fiber bundle to be treated as a water f11 liquid. Typically, the sizing agent is used as an aqueous solution of 10/g to 209/g. As the solvent, water alone or a mixed solvent of water and acetone, methanol, ethanol, etc. is used. , the use of a mixed solvent is water! 1j When using a single solvent,
It is effective when the solution viscosity is too high to make it difficult to use. When the solution viscosity becomes high, the strands (fiber bundles) tend to stick to each other, causing dry fuzz.

When a mixed solvent is used, an aqueous solution containing 40 to 80% of an organic solvent is used.

The amount of adhesion of the sizing agent needs to be 0.01 to 0.5%. If it is less than o or oi weight%, the effect of suppressing fuzz will not be improved, and if it exceeds 0.5% by weight, the strands will stick to each other and become nil after carbonization. The preferred range is 0.1-0.3'ii1%.

Normally, in order to attach a sizing agent aqueous liquid to the fiber bundle to be treated,
This can be carried out by any method such as passing the fiber bundle by immersing it in an aqueous liquid, spraying the m-fiber bundle with an aqueous liquid, or bringing it into contact with a roller. In order to attach the aqueous sizing agent to the flame-resistant fiber bundle, whichever of the above methods is used, it is preferable to squeeze and dry the sizing agent with a pressing roller after the adhesion. This is because the aqueous sizing agent is attached to the flame-resistant uA411t, which is squeezed with a presser roller while preventing surface damage, and the agglutination that occurs during the flame-proofing process is defibrated, and the moisture content of the fiber bundle after squeezing is reduced using a dry base. 45
This is because if the strands are dried in a state of about 10%, the strands will not stick to each other during drying and drying can be carried out.

After applying the sizing agent, it is dried at a temperature of 250° C. or lower. If the fiber is introduced into the carbonization furnace without drying, the strength of the product fiber will decrease. In addition, when dried at a temperature exceeding 250℃,
rl@ occurs in the fiber bundle and the performance of product 11 fibers deteriorates.

a: The powder preparation and drying are preferably carried out in the state of the strand to be carbonized. Doubling thread, or U state,
1/I rolled or wound on a bobbin.

If this is done, the lands will connect to each other, which is inconvenient.

Tables 1 and 2 below show the amount of sizing agent deposited and the effect of drying once on the flame-resistant fiber braid.

Table 1 (Note) Sizing agent: Bi-molecule MIG to 1.1 million polyethylene oxide (Nide drying temperature: 130°C *; outside the scope of the present invention Table 2 (Note) Sizing agent: Molecule 1i 110 to 1.1 million polyethylene oxide (Nide) Amount of sizing agent deposited: 20.1% by weight *: Outside the scope of the present invention Next, the present invention will be explained with reference to examples, and comparative examples will be shown.

Example 1 Ten acrylonitrile fiber bundles consisting of 0.9 denier 6000 filaments were flame-retardantly treated at 250'C in an oxidizing atmosphere, and the resulting flame-resistant fiber bundles were treated with a sizing agent listed in Table 3 below. The sample was immersed in a 2a/Q aqueous solution, squeezed with a pressure rubber roller, dried at a temperature of about 130°C, and carbonized in a carbonization furnace at 1400°C in a nitrogen stream. After surface treatment, washing with water, drying, and resin adhesion, the amount of fluff accumulated on the guide at the exit of the dryer was measured. In addition, the number of fuzz, number of fuzz, strength, adhesion rate, and elongation of the wound product were measured. The results were as shown in Table 3.

In addition, the conformability of the product and the number of stickiness were measured by the following method.

[Fuzz count measurement method] Soak 6000 filament strands in acetone (6000 filament strands).
After dissolving and removing the sizing agent, the fibers were stretched to a length of about 1.5 m, air-dried with Ahiton, and then opened by blowing air, and the number of fluffs that protruded was counted over a length of 11 m.

[N number of pieces measurement method]

A 6000 filament strand is cut into a length of 3n+a+, placed in acetone and subjected to ultrasonic cleaning to dissolve and remove the sizing agent, and then the thick n-front threads are counted under a microscope under 6.3 magnification.

Table 3 (Note) PEO: Polyethylene A Kylide MC: Methyl cellulose 11 Mc: Hydroxymethyl cellulose PVME: Polyvinyl methyl ether Example 2 Using an aqueous solution of methylcellulose 2 (J/Q) as a sizing agent, the dried tea f listed in Table 4 below was used. [Other than adopting
Carbon fibers were produced in the same manner as in Example 1. The measurement results for the number of fuzz, etc. of the product were as shown in Table 4.

Table 4 (Note) Old M: 0.08%

Claims (1)

[Claims] When supplying the flame-resistant fiber bundle to a carbonization furnace and continuously heat-treating it to produce acrylonitrile-based carbon fiber, the flame-resistant fiber bundle is preliminarily treated with polyethylene oxide having a molecular weight of 100,000 or more,
methyl etherified, ethyl etherified or hydroxyethyl etherified cellulose, or (and)
An aqueous solution of polyvinyl methyl ether was deposited at a deposition amount of 0.01 to 0.5% by weight, and then 250%
A method for producing carbon fibers, comprising drying at a temperature of 0.degree. C. or lower, and then performing the heat treatment.