JPH02133618A - Production of pitch-based carbon yarn and winder for pitch yarn - Google Patents

Abstract

PURPOSE:To obtain yarn having a few constituent single yarns useful as electroconductive material, electromagnetic wave shielding material, antistatic material, etc., by infusibilizing pitch yarn subjected to melt spinning as a bundle of many single yarns, carbonizing and dividing the bundle into plural yarn bundles. CONSTITUTION:Pitch yarn subjected to melt spinning is infusibilized and carbonized as a bundle of many single yarns and divided into plural single yarns or plural yarn bundles having approximately the same number of constituent yarns to give the aimed yarn. The number of constituent yarns of the divided yarns is preferably one. The diameter of single yarn is preferably >=30mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a yarn having a small number of single fibers constituting carbon fibers. The present invention is particularly directed to a method for producing pitch-based carbon fiber monofilaments or yarns having a small number of monofilaments.

The carbon fibers of the present invention have a small number of constituent single fibers, and the constituent single fibers are generally thick, but the overall system is different.

Carbon fiber composition Yarn with a small number of single fibers is a conductive material (heating element, electrode material), JIM wave shielding material, antistatic material,
Heat-resistant and chemical-resistant materials (filter cloth, work clothes, protective clothing, protective equipment,
used as insulation material), etc. Since conventional carbon fibers are used for m-fiber reinforcement, the number of constituent single fibers is large and the threads are thick, making them inconvenient to handle as raw materials for such materials.

Constituent Carbon Fiber Yarn with a small number of single fibers, especially monofilament, is produced by a CVD method or the like using boron, silicon carbide, silicon nitride, etc., and exhibits excellent performance as a core material for ceramic fibers and the like.

[Conventional technology]

Conventionally, synthetic fiber monofilament has been produced by extruding the spinning solution from a spinneret and assimilating it, then continuously drawing and heat-treating it, and then dividing the fibers into single or several fibers and winding them. It is manufactured from.

Although this method is simple and does not require sophisticated technology, it produces products of high quality and accuracy, and is used for many synthetic resins such as polyamide, polyester, and polyolefin.

In addition, fibers with high strength and elongation, such as polyamide,
A method is also used in which a filament yarn having a relatively large single fiber denier is separated one or two at a time while being untwisted and then wound.

However, in the case of pitch fibers, it is difficult to employ these methods because the strength of the fibers after spinning is extremely low. If these methods were adopted, there would be an extremely large number of yarn breakages, and when a yarn breakage occurs, it would be difficult to re-introduce the yarn without cutting other yarns, which would reduce process utilization and product yield. It causes very little problem.

In the case of pitch fibers, the strength after spinning is extremely low, and the strength gradually increases as processing progresses.
It becomes possible to process the fibers in the same way as ordinary synthetic fibers when the infusibility treatment is completed and carbonization has progressed slightly.

[Problem to be solved by the invention]

Carbon fibers are manufactured by carbonizing various organic fibers.

The process leading to carbonization is generally long, and the reaction proceeds through intervals of various conditions. For this reason, if carbonization is performed with a thin yarn with a small number of constituent single fibers, the processing i will be extremely high.Also, the main use of carbon fiber is to strengthen composite T with village fibers, so it is structured like fibers for clothing. Demand for yarn with a small number of single fibers was extremely low.

However, in recent years, the quality of carbon fiber has improved, and its unique physical properties are attracting attention as a fiber for industrial use. Therefore, there is a tendency for demand for yarns with a thickness similar to that of general synthetic fibers to increase rapidly.

[: Means for Solving Problem 5] The present invention is based on the present invention, in which melt-spun pitch fibers are made into a bundle with a large number of single fibers, and after being subjected to infusibility and carbonization treatment, the number of single fibers or the number of constituent fibers is Approximately equal multiple ′a
This is a method for manufacturing carbon fiber characterized by dividing it into fiber bundles.

Pitch fibers immediately after melt spinning are extremely weak and brittle, so
It is extremely difficult to handle this as one or several single fibers. However, after the pitch fibers are infusible and carbonized, the strength of the fibers increases, the bending becomes less, and it becomes possible to handle a single thread or several threads as ordinary threads. In the present invention, the number of 11 fibers is increased until the pitch fibers are produced and become slightly carbonized and brittle. This method consists of dividing the yarn into a plurality of fiber bundles to produce yarn with a small number of constituent single fibers.

A carbon fiber monofilament can be manufactured by using only one single fiber.

Preferably, it is divided into 10 or more bundles or single fibers.

A small number of fibers means that the bundle of fibers that are handled at a weak and brittle stage is thin as a whole, so that the strength necessary for handling cannot be obtained.

The carbon fiber used in the method of the present invention is a single fiber or 7 to 14μ
Although it may have a normal diameter of about a leap, it is preferable that the single fiber has a diameter of 20 μm or more, most preferably 30 μm or more.
It is composed of single fibers with a diameter of μm or more. The strength tends to increase as the single fiber diameter decreases, but in the case of a yarn with a small number of constituent single fibers, such as the carbon'R fiber of the present invention, processing tends to become difficult because the strength of the yarn decreases. . It also tends to be less resistant to wear. This tendency is particularly noticeable when the single fiber diameter is 20 μm or less.

/lL There is a tendency for the strength to decrease as the fiber diameter increases, but in the case of carbon fibers made from optical anisotropic pitch, this is not the case with other types of carbon fibers.

As the diameter of the single fiber increases, the g resistance improves, so
When the carbon fiber of the present invention is used as a fiber aggregate without being coated with a carbon fiber material, it is preferable that the diameter is large. However, as the diameter of the single fiber increases, the infusibility becomes more difficult, requiring long-term oxidation treatment at low temperatures.Also, pitch fibers tend to become non-uniform during spinning.For these reasons, The diameter of the carbon fiber single wire !1 of the present invention is preferably 250 am or less, most preferably 100 μm or less.

The strength of PAN or rayon-based carbon fibers rapidly decreases as the diameter of the single fiber increases.

The reason for this is said to be that the strength of the fiber depends on whether or not there is a roughness on the surface, and as the diameter increases, the probability of scratches increases. However, pitch-based carbon fiber,
Single m! The surface is made of titanium, which has the advantage that there is little decrease in strength when the diameter of By coating with carbide, silicon carbide, etc., corrosion resistance against substances that strongly corrode carbon, such as molten metal, can be ensured.

The carbon a-fiber monofilament of the present invention has strength, corrosion resistance,
Although it has excellent rigidity and shape retention, when used as a fiber-reinforced material for composite materials, it may have poor flexibility and poor moldability. However, due to the flow of matrix components during molding, disturbances t1 occur in the arrangement and arrangement of the stranded fibers.
This has the advantage of causing fewer defects in the molded product.

In the production of the fibers up to 1 inch of the present invention, -C is preferably formed by forming the pitch f and the fiber into a thin plate shape and winding it up, followed by infusibility and carbonization while maintaining the plate shape. When forming, a glue or a cohesive oil is applied and the thin plate is rolled up to prevent it from turning over or splitting.

During this winding, it is preferable to use a twill guide for the winding machine that has a narrow gap to the extent that the position of the single fibers does not shift. This gap may be formed in the shape of a guide, or may be formed by combining the 1z flattened 2nd position of the fiber bundle and a wide guide. The gap between the twills is preferably smaller than 218 mm of the fiber diameter.

The wound thin plate-shaped fiber bundle is drawn out without turning or splitting, and is made infusible and carbonized. During this time, glue and oil are removed by incineration.

It is also possible to perform continuous processing from the spinning of pitches to the carbonization process without winding.6 However, since there are differences in the preferred processing speed for each step, it is preferable to wind the fibers after pitch spinning. .

The pitch used in the production of the carbon fiber of the present invention is a highly softened pitch that can be melt-spun and made infusible.Although the pitch may be isotropic, it is preferably optically anisotropic. During the infusibility and carbonization process of optically anisotropic pitch fibers, there is no need to apply tension to P as with N-based carbon fibers, and even when processed without tension, high strength can be achieved. , fibers with high elastic modulus can be obtained.

[Effect]

In the present invention, the pitch fibers to be melt-spun are made into a bundle with a large number of single fibers, and after being infusible and spun (1f), a plurality of single fibers or a plurality of fibers having approximately the same number of fibers constituting the fibers are formed. This is a method of dividing into bundles.

Since the pitch fibers immediately after melt spinning are extremely fragile and fragile, it is extremely difficult to handle the pitch fibers in the form of one or several filaments. However, pitch m
After the &lt is infusible and carbonized, the strength of the fiber increases and the brittleness decreases, making it possible to process and handle a system with one or several male constituents as sweat-permeable thread. becomes possible.

In the present invention, from the production of pitch fibers, the process is carried out by increasing the number of single fibers until carbonization progresses slightly and brittleness decreases, and then 'i! This is a method of dividing into i number of single fibers or iFi fiber bundles having approximately the same number of single fibers to produce a yarn with a small number of constituent single fibers.

〔Example〕

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

Actual example 1 A spinneret made of petroleum pitch with a softening point of 285°C and an optical anisotropy fraction of 100% and having a spinning hole with a diameter of 0.08 mm at the narrowest part of the spinning hole and a diameter of 0612ffiII+ at the outlet of the spinning hole. Melt spinning was performed at a spinning temperature of 310°C.

Pitch discharge amount 23.2g78ON・min, winding speed 17
The speed was 5 m/min. The spun bundle of 80 single fibers was oiled with silicone oil, spread on a roller to a width of about 3.2 mm, and wound up to maintain the same width.

The traverse guide of the winder is 0.05mm thick @3
A slit of ゜2+I1m was used as a guide hole, and the thickness of the slit was made smaller than twice the pitch fiber diameter so that the arrangement order of the fibers did not change.

The spun fibers were made infusible by a conventional method and then carbonized at a maximum temperature of 1400°C. During processing, the fiber bundles were placed on a net conveyor to prevent them from turning over or breaking.

After the carbonization treatment, the obtained fibers were separated and wound up into 80 monofilaments. The resulting fiber and neck have a diameter of approximately 3
It is 2 μl thick and has a strength of 205 kg/am.
2. The elastic modulus was 20,000 kg/ram2.

Comparative Example l An attempt was made to immediately wind the pitch fibers spun in Example 1 one by one according to the conventional monofilament manufacturing method, but there were so many yarn breaks that it was impossible to wind them at a practical cost. It was judged possible.

Example 2 Instead of the spinneret of Example 1, a spinneret having 1,000 spinning holes with a diameter of 0.08 mm at the narrowest part and a diameter of 0.12 + nm at the exit of the spinning hole was used, and the same pitch was used. Using this method, pitch fibers were spun at a spinning temperature of 300°C.

Pitch discharge fIL 250g 1 minute, winding speed 150m/
It was a minute.

The spun fibers were bundled using a polyacrylamide sizing agent and wound up as a tape-shaped molded product with a width of 40+++ m. The wound tape was subjected to an infusibility treatment using a conventional method, and was further carbonized at a maximum temperature of 2200°C. During processing, the fiber bundles were prevented from turning over or cracking.

After the carbonization treatment, the obtained fibers were separated and wound into 40 multifilaments.6 The obtained fibers were multifilaments consisting of about 25 single fibers with a diameter of about 32 μm and had excellent processability. The strength is 235kg/1
lIl112, the elastic modulus was 43.800 kg/mm2.

Example 3 Instead of the spinneret of Example 1, the diameter of the narrowest part of the spinning hole was 0.1211111 mm, and the diameter of the outlet of the spinning hole was 0-25 mm.
Melt spinning was performed at a spinning temperature of 300° C. using a spinneret having a spinning hole of 300° C. The pitch used was a petroleum pitch with a softening point of 282° C. and an optical anisotropy fraction of 94%.

Pitch discharge amount 22g 150H・min, winding speed 175m
/minute. After oiling the spun bundle of 50 fibers with silicone oil, it was rolled on a roller for about 3.
It was rolled out to a width of 2 mm and wound up to the same width.

The traverse guide of the winding machine had two small rollers that sandwiched the fiber bundle and traversed it, and the pitch fibers were wound side by side side by side. This fiber bundle was subjected to an infusibility treatment in a conventional manner without changing its flat shape, and was further subjected to a mild carbonization treatment at a maximum temperature of 630° C., and then divided into 50 monofilaments and wound up.

The resulting fibers have a diameter of approximately 50. czn, strength 15J/mm
2. The elongation was 2.4% and the elastic modulus was 625 kg/mm2.

This fiber has excellent kneadability, and by heat-treating it at a high temperature after processing, it was possible to make a carbon fiber with high strength and high elasticity of 58.

〔Effect of the invention〕

The present invention relates to a method for producing a yarn having a small number of carbon fiber constituent single fibers. The present invention particularly relates to a method for producing pitch-based carbon fiber monofilaments or yarns having a small number of monofilaments.

Carbon fiber composition Yarn with a small number of single fibers can be used as conductive materials (heating elements, electrode materials), electromagnetic shielding materials, antistatic materials, heat-resistant and chemical-resistant materials (filtering cloth, work clothes, protective clothing, protective gear, heat insulation materials), etc. used. Since conventional carbon fibers are used for fiber reinforcement, they have a large number of single fibers and are thick, making them difficult to handle as raw materials for such materials.

Yarn with a small number of single fibers, especially monofilament, exhibits excellent performance as a core material for ceramic fibers and the like manufactured by coating boron, silicon carbide, silicon nitride, etc. by CVD method or the like.

that's all

Claims (1)

[Claims] 1. Melt-spun pitch fibers are made into bundles with a large number of single fibers and subjected to infusibility and carbonization treatment, and then divided into a plurality of single fibers or a plurality of fiber bundles having approximately the same number of fibers. A method for producing pitch-based carbon fiber, characterized by: 2. The method for producing a carbon fiber monofilament according to claim 1, wherein the number of fibers constituted by the divided fibers is one. 3. The method for producing carbon fiber according to claim 1, wherein the carbon fiber is divided into 3, 10 or more fibers or fiber bundles. 4. The method for producing carbon fibers according to any one of claims 1 to 3, wherein the carbon fibers are composed of thick single fibers having a diameter of 20 μm or more. 5. Any one of claims 1 to 4, characterized in that the pitch fibers are wound into a thin plate-like bundle, and then infusible and carbonized are performed while maintaining the plate-like bundle shape. The method for manufacturing carbon fiber described in . 6. The method for producing carbon fibers according to claim 5, characterized in that a traversing guide having a gap narrow enough to prevent displacement of the single fibers is used when winding the pitch fibers. 7. Used in the production of carbon fibers according to claims 5 and 6,
A winding device for pitch fibers having a traverse guide with a gap smaller than twice the fiber diameter.