JPS5930918A - Preparation of carbon fiber - Google Patents

Abstract

PURPOSE:To obtain carbon fiber in a filament state, by spinning a pitch raw material, sending it through rollers and a static eliminator to an air sucker, providing it with a liquid, bundling it, oxidizing it with air, carbonizing it in an inert gas atmosphere under heating. CONSTITUTION:Preferably a coal or petroleum pitch raw material is dissolved in a spinning device under heating, extruded from the spinning nozzle 1, optionally passed through the collecting guide 2, sent through two or more of the rotary rollers 3 and 4 and one or more of the static eliminators 6 and sucked in the air sucker 5. When the pitch yarn is in the air sucker 5, or immediately after it is passed through the air sucker 5, the yarn is provided with a liquid, collected and put in the fiber can 8. The yarn is then oxidized with air, made infusible, and carbonized in an inert gas atmosphere under heating, to give desired carbon fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing long carbon fibers using pitch-based raw materials.

Conventionally, pitches have been consumed in large quantities as starting materials for coke and carbon materials, but it has been devised to use these raw materials to produce carbon fibers, which are now industrially produced in large quantities. Carbon fiber can be roughly divided into two methods: one is made from acrylonitrile-based synthetic fibers, and the other is made from melt-spinning pitch-based raw materials. The process is endless#
The fibers are processed continuously, and the standard product shape is a long fiber-like rolled shape. However, pitch-based carbon fiber can be used in the form of so-called chopped 7-eyeper (short fiber) or in textile products processed using it as a raw material, such as twisted yarn, felt, etc.
It is cloth, paper, etc., and as a product where the fibers are aligned in the length direction, it is at best in the shape of Tokuka Nuribar. This is because when pitch-based raw materials are melt-spun to obtain yarn for carbon fibers, the temperature dependence of the melt viscosity of the raw materials is so steep that the safe operating temperature range without yarn breakage during spinning is extremely narrow. Slight irregularities in temperature control, or even unavoidable fluctuations in the spinning area, such as minute changes in airflow, can also lead to the risk of yarn breakage, and therefore, in practice, including acrylonitrile fibers, It is difficult to collect long fibers in an endless state like synthetic fibers produced by melt spinning such as nylon and polyester. Furthermore, the spun carbon fiber yarn itself is extremely fragile, and it is no exaggeration to say that it is impossible to handle the fiber in the usual way, such as rewinding it as with general synthetic fibers.

Therefore, despite the desire to produce carbon fibers in the form of long fibers, the reality is that the shape of short fibers has no choice but to be avoided. The most common manufacturing method currently in use is to turn the pitch yarn raw material discharged from a molten corridor spinning nozzle into fibers and wind it onto a rotating bobbin, but as mentioned above, the raw yarn itself is fragile. It cannot be wound thickly, so it is wound very thinly, the bobbin is changed as needed, and the thinly wound raw yarn is cut into two parts, for example, into a squiver shape, and then it is made into a squiver shape. After being subjected to infusibility treatment by so-called heating oxidation, which is carried out in the manufacturing process, carbonization treatment is performed in an inert gas atmosphere, and the product is cut to the desired fiber length. The extent to which the chopping step to form the final product is changed before or after infusibility.

Pitch-based carbon rim m can be roughly divided into low-grade, which has low strength and low elasticity, and high-grade, which has high strength and high elasticity, and the latter is made by mesophene's liquid crystal spinning method. If a final product of any type can be obtained in the form of a filament, it would greatly contribute to expanding the range of uses and eliminating waste by increasing product yield in the manufacturing process.

For example, VC for use in asbestos substitute material waste, which has a large potential demand for low-grade materials, and vehicle structural materials mainly for automobiles.
For example, the production of roving, which is a representative product form of glass fiber, not only streamlines the manufacturing process, but also enables the use of a wide range of processing techniques that use all pitch-based carbon fibers. Become.

As a result of research to obtain long-fiber carbon fibers from pitch-based raw materials, the present inventors have completed the development of tJA gold.

An object of the present invention is to provide pitch-based carbon fibers in the form of long fibers. Another object is to provide a process for producing certain fibers #I industrially and easily.

In the method of the present invention, when melt-spinning a pitch-based raw material, it is taken through an air sucker through at least two rollers and at least one spherical device, and the pitch-based raw material is drawn into the air sucker or immediately after passing through the air sucker. The collected threads are oxidized in the air to make them heat-infusible.
It is then characterized by being heated and carbonized in an inert gas atmosphere.

-5-" Pitch-based raw materials that can be applied to the present invention include not only the black carbonaceous solid residue obtained when distilling tar obtained by dry distillation of organic substances, which are representative of all coal, but also SR.
Examples include solid content that has been solvent-refined in the coal liquefaction process or tar extraction process, referred to as C, and petroleum asphal HXO heat-treated products. Pitches made by thermally decomposing polymers such as polyvinyl chloride and low-molecular organic compounds such as tetoxpenzophenazine, and furthermore, any of these pitches can be heat-treated in an inert atmosphere to form an optically anisotropic structure. It also includes things that have been formed.

In melt spinning of pitch-based raw materials, since the spun raw yarn is fragile, it is possible to collect thick windings on a bobbin such as synthetic am using the usual melt spinning method.Therefore, in the method of the present invention, yarns are collected in the form of long fibers. Therefore, using an air sucker, the fibers are stored in a fiber can without being damaged through the air sucker through at least two rollers and at least one static eliminator with the help of an air flow of 9L. The roller 6 used here is typically made of a metal roller with a mirror-like finish or a satin finish, but rubber-coated or resin-coated rollers can also be used. One roller is usually preferably installed below the vertical line of the spinneret, and the other rollers are positioned as appropriate depending on the working conditions. However, one of the other rollers is used as a pick-up for storage in the 71-year-old. The fiber can may be made of a perforated cylinder and use a strip P18 that rotates eccentrically on the floor surface, if necessary.

The pitch-based raw material is hydrophobic due to its U acid component, and the raw yarn discharged by melting it does not exhibit any moisture or water absorption properties. Therefore, in the process of passing through an air sucker via at least two rollers after leaving the spinning nozzle, the fibers are exposed to static electricity due to the running contact between the fibers as well as between the fibers and other materials. As long as the work is continued in this charged state, the fibers will get wrapped around the fibers, causing fine cuts, and even if they can be stored in a fiber can via an air sucker, they will not be able to be collected in the form of fiber bundles. , each single fiber remains entangled, making it completely impossible to transfer it to the next process in the form of a thread. 4. In order to remove static electricity and focus the filaments, oiling methods such as those used for ordinary synthetic fibers, such as bringing the traveling fiber into contact with the surface of a rotating roller with an oil film attached to the surface, are used in this case. It cannot be used because the thread is extremely fragile. Due to the resistance that the spun yarn receives when passing through a liquid layer made of various oil agents, stress is transmitted to most of the spinning nozzle surface of the yarn, and most of the fikumen In- is cut at that point.

In the method of the present invention, the liquid f is applied and concentrated just before the long fiber yarn is stored in the 7-eye percence through the air sucker, so the yarn discharged from the spinning nozzle enters the hooker. In the process up to this point, the friction between the running fibers, the focusing guide used if necessary, and the static electricity generated during contact with at least a 2g roller accumulates on the fibers, resulting in disordered yarns and damage to the rollers. Undesirable phenomena such as tangles that cause thread breakage occur. [
Quiet? Actively remove XX energy and eliminate the causes of these troubles -1? l, mellow. The static eliminator used in the present invention is usually a corona discharge type static eliminator with a high perspiration current, and is installed facing the threads of the running pitch fiber, depending on the amount of p# electricity generated by the fiber. -i The high-voltage current capacity of the static eliminator, the shape, number, installation position, etc. of the static eliminator may be selected as appropriate depending on the running lip of the fiber, and this is not intended to be completely limiting.

Usually, the static eliminator is preferably installed immediately after the pitch fibers pass through the focusing guide and immediately after each roller passes.

In this way, just before the pitch fibers are introduced into the air sucker and stored in the fiber dancer, the entire liquid is applied to the surface of the pitch fiber yarns by spraying with a spray nozzle or by injecting liquid from the yarn suction hole or air introduction hole of the air sucker. do. Unlike these methods, a thin film of liquid is formed in a certain area of a V-shaped recess called a lubricating nozzle, and the fiber surface is wetted by a method in which the fiber threads penetrate through the thin film. It is also possible. For the purpose of applying liquid to the pitch fiber yarn surface immediately after passing through the air sucker, we do not care about the method.
Any method may be used, but from a practical point of view, a spray method is most suitable.

Pitch fibers whose surfaces are wetted with a liquid do not absorb the liquid, but rather a large number of filaments adhere to the same or each other and converge. The fibers are stored in a 7-eye perdance as long fibrous yarns that remain bundled.

As for the type of liquid to be used here, for example, liquids that dissolve most or part of the pitch fibers, such as quinoline, pyridine, benzene, and toluene, are inappropriate, and the pitch fibers stored in the 71 Iperguns are not suitable for oxidation treatment. Then, carbonization process is performed to create the desired carbon fiber. i! '# Components that remain as ash in an ambient atmosphere, such as -Ha, -K
Liquids containing compounds forming metal salts such as , -Ca, phosphoric acid esters, and certain 10-sulfuric acid esters are not preferred. Basically, any aqueous or non-aqueous liquid containing compounds other than these can be used, but the liquid itself used in the oxidation treatment and carbonization process,
In vI/1, it is necessary to avoid sticking between fibers due to solutes contained in the liquid. In this sense, water alone (including pure water) can be used as an ideal liquid, but in some cases, the adhesion between fibers during wetting with ilt is insufficient, and the yarns stored in the fiber gunne cannot be bundled. Sexual disorder may also occur. It is possible to use an aqueous oil agent or a non-aqueous oil agent as the liquid other than water alone, and the former is particularly preferably a nonionic penetrant. For example, /nyllephenol, or ethylene oxide adduct of octylphenol (number of moles of ethylene oxide added: e.g. 7 to
10), ethylene oxide adduct of intermediate to higher alcohol-I represented by the general formula Rt)(CH,CH,O)n+(where R:C, ~1. alkyl group, n=4~ 15
), ethylene glycol, propylene glycol, and polyethylene oxide alone (average number of molecules 200 to IQ
, neo) is a typical example. The solution concentration of these compounds is preferably in the range of 0.01 to 1.1%, particularly preferably in the range of 0.05 to 0.5%. Furthermore, as the aqueous oil agent, an aqueous solution prepared by diluting an emulsified liquid, which is usually used as a fine spinning oil agent, with water so that the solid content concentration falls within the above-mentioned range can also be used. In either case, if the solid content concentration exceeds 10%, it is not preferable because interfiber adhesion is likely to occur during the oxidation treatment process of pitch fibers. In the case of an aqueous oil agent, a water-soluble oxidizing agent such as hydrogen peroxide can be mixed and added to an aqueous solution of the treatment composition.

Mineral 71+J (Red Hood 100) is a non-aqueous oil.
The use of sub-seconds alone is surrogate. If the Red Hood number of the mineral oil is 100 seconds or more, the liquid viscosity is high, making it difficult to spray, and it is difficult to adhere to the fiber surface as fine droplets, making it difficult to form uniformly bundled threads. It is preferable to use an oil with as low a viscosity as possible as long as the environment in which the tree is cultivated allows.

When using any liquid, the dispersion varies depending on the composition of the liquid, but in the case of water alone, it is 2 to 5% by weight,
In the case of water-based filJ, the range is preferably 1 to 4%, and in the case of non-aqueous oil, it is preferably in the range of 0.2 to 2%.Whether the liquid supply method is spraying or using a spray M nozzle, the fsl ratio is as above. Adjust the supply amount of liquid and oil nozzle so that it is within the range of .

An example of paper cutting and collection according to the method of the present invention will be explained with reference to the drawings, but the present invention is not limited thereto.

That is, in FIG. 1, 1 is a spinning nozzle attached to a spinning device, and the raw material pitch is heated and melted and discharged into the air from this nozzle, and the spinning speed is 100 to 1500.
Spun with. 2-piece focusing guide, 5#i pick-up loco,
4Vi final take-up roller, 5 air sucker, 6 static electricity eliminator, 7 liquid spray nozzle, 8 cylindrical)
1 Ipakunnu, 9Fi did not show much of the stored long fibrous pitch fibers.

The pitch fibers discharged from the nozzle are passed through the focusing guides 2 and 3, 4 as necessary. The liquid is taken up by a rotating roller 13- and is sucked by an air sucker 5, and is stored in 8 while being applied to the surface of the fiber using 7. In this case, the air suction part diameter and length of the air sucker to be used are selected as appropriate depending on the total number of yarns and the spinning speed, and the compressed air pressure and air volume for the air sucker are also selected as appropriate. In this step, the electrostatic charge 9L#-i6 that is charged due to the friction of the running yarn is actively removed by a removal device.

Applying liquid to the fiber surface, for example, for spinning synthetic fibers.
If the process is carried out before the winding roller as shown in FIG. Not enough. Either drop the liquid at the same time at the point where the fiber thread is sucked in at least 5, or transport it by the compressed air blown into 5 to make the liquid into a tw shape and send it into the nozzle of 5, or else the thread will pass through 5. An important requirement of the present invention is to apply it immediately afterward. The long-filament pitch fibers 9 stored in the fiber guns 8 in this way are completely bundled into one thread without any separation of individual threads. It is a phenomenon that the fibers can be collected without any damage to the fibers. The method of spinning an extremely brittle, completely hydrophobic material with a fully focused NTC long fiber-like material was completely unknown in the past, and could actually be carried out for the first time in the method of the present invention. Even more surprising, JITVc is that although the brittleness of each single yarn has not been improved in any way, when many raw silks are bundled into a single thread by the liquid according to the present invention, it is a highly energized fiber. J said that it would be possible to handle the same way. That is, if necessary, the end yarn of 9 stored in 8 can be lifted up and moved to the pond part (2), or it can be wound up into a ``skein'' by passing it through a spinning wheel on a rotating table.

The second-length fibrous pitch fibers stored in the above-mentioned Ipaken 7 are then subjected to oxidation to change them into a heat-infusible state. As for the oxidation treatment, there are two main methods: a dry method using all air, and a method performed in an oxidizing base liquid. Both methods are possible in the present invention, and are not limited thereto. I! The method of heating and oxidizing in air is also simple and convenient.

In addition, when doing this, depending on the holding form of the long pitch fibers, it is a good idea to widen the fission curve area as much as possible and bring it into contact with Souya 1, but that is not the case. As a practical method, 1. ! One method is to transfer the fiber to 1 and proceed with oxidation from the surface of the fiber while moving it in a heated atmosphere where air is present. Alternatively, the fiber can itself is made of wire mesh or a metal perforated tube, and the treated fox yarn is stored in it, and the string is cut at a point to make it an independent loft. ＼′+! One method is to proceed with atmospheric oxidation. In any case, the temperature gradient in the atmosphere during oxidation is set at 03-7°C/MiIl, and the temperature is raised to 20-150°C higher than the softening temperature of the raw material pitch, and the temperature is kept within that temperature range for 5 minutes. Hold for ~1.5 hours.

During this time, the air in the atmosphere may be static, actively stirred, or ventilated.

After the infusibility treatment, the long fibrous pitch fibers are introduced into a heated 011VC under an inert gas atmosphere and heated and carbonized to form long fibrous carbon fibers. In this case, the movement of the yarn during the carbonization process is possible either under tension or under no tension, and the temperature gradient during temperature rise in the heating region is 6.-20°C/-, with a maximum temperature of 900 to 2000°C. The maximum temperature holding time is 5~
The carbonization process is completed in 50 minutes. The treated fibers are carbon fibers with sufficient tensile strength that they can be unwound, for example into rovings, according to conventional fiber handling methods.

In the present invention, a spun yarn that is made brittle and has no Iykm property or water absorption is introduced into an air sucker via a take-up roller, and immediately after that, a liquid is applied to the fiber 2It surface to bundle each single fiber and place it on a bobbin. By carbonizing the collected long fibers without winding them into long fibers, it is possible to produce long fiber carbon fibers, which could not be obtained from conventional pitch-based raw materials.It has a wide range of applications. It goes beyond.

The present invention will be specifically explained below with reference to Examples, but the present invention is not limited thereto.

17- Example 1 Coal cool pitch with an average molecular weight of 600 and a softening point of 220°C was filled into a vessel type Merck, heated from the outside under nitrogen gas to make white mud 250°C, and the molten coal tar pitch was pumped into a gear pump. Quantitatively pump liquid at ＼Kouya 0.
Discharged from a spinning nozzle with a length of 5 m and 32 holes to the outside of the yarn.
2 was guided to the workpiece through two rollers rotating at a surface velocity of 1. In this case, a focusing guide is installed directly below the nozzle, and a corona discharge type static electricity remover is installed between it and the 10th lar, and between the 10th lar and the 20th lar. After removing static electricity from the fibers, the fibers were absorbed into an air sucker. Air soccer #i suction port holder 8m used here
+, Using an empty SL rotating type with a length of 150fi, directly below the nozzle, tap water at room temperature was sprayed at a flow rate of 1i-500sd/- from a spray nozzle or an air sucker to make the yarn sprayed to freshen the yarn surface. The fibers were stored in Ipergunnu 71 in a state where they were soaked with 4% adhering water per fiber weight.

18- After 50 minutes of spinning (continuation time), the continuous yarn was cut once, and the end yarn was held and the long fiber yarn was arranged in a meandering pattern on a wire mesh made of thorn tenle lambda in a heating furnace maintained at a maximum temperature of 500°C. I passed through it. In this case, the yarn transfer temperature gradient is 5
The holding time at 00'C was set to 0 minutes. The yarn taken from the heating furnace remained unmelted even when exposed to flame. This infusible yarn was also placed in a 7-eye parken 7, and the yarn end was further guided and placed on a stainless wire mesh in an untensioned state, and nitrogen gas was introduced at a center temperature of 1000°C. The fluid was transferred through an electric furnace.

In this case, the long fibrous yarn was carbonized under conditions such that the temperature gradient was 5°C/-, the maximum temperature was 1000°C, and the holding time was 10 minutes. In this way, long-fiber carbon fibers were collected using coal tar pitch as a raw material. The physical properties of this fiber are fiber diameter 16μ, tensile strength aokq/d, and tensile modulus 2900.
It was garlic/-.

As a comparative experiment, the fibers were spun under the same conditions except that tap water was not sprayed, and the fibers sprayed from the air sucker caused single filament breakage and entanglement, resulting in partial filament formation. Even if you get rid of the fibrous structure, it will still be lumpy.
However, it was not possible to extract the long fiber-like filament form at all.

Example 2 Solvent refined charcoal (abbreviated as 5RCJ) with a molecular weight ao o of Hei 9 and a softening point of 245° C. was charged into the same spinning neck as in Example 1, and the internal temperature was increased to 270° C. over nitrogen gas to melt it. 0.25
Paper discharge from a nozzle with 28 m-diameter holes, surface speed 5
Low 2-2 rotating at 00m/-? Humiliating air soccer through fc. Two static electricity removers t-1ts were used as in Example 1 while the fiber was running. Then, a pouring ff1l nozzle was installed directly below the nozzle of the air sucker, and mineral oil (
(Lethood 40 seconds) Oil 111 by injecting alone
[Th was stretched, and the sprayed raw yarn was passed through it to deposit a correlation of 1% per fiber weight on the surface.\Fiber Gunnu was stored as a long fiber-like bundled yarn. The obtained fibers could only be lifted and transferred in a bundled state.

The stored long fiber yarns were all the same method as in Example 1 F. First, they were heated in air to a maximum temperature of 270°C using a mobile device, and were thermally infusible without sticking between each fiber, and were further carbonized at a maximum temperature of 950°C. After treatment, fiber diameter 14μ, tensile strength 72 kQ/m
4. Long fibrous carbon fibers with a tensile modulus of 2500/- were obtained.

In this case, when a discharge type static electricity remover was not installed and only the oil was applied using a lubricating nozzle directly below the air sucker nozzle, the pitch fibers discharged from the spinning nozzle generated significant static electricity, making it difficult to run. The yarn spread out every single yarn and wound around the surface of the 10th layer, making it difficult to move the kI fibers to the air sucker position, making it impossible to collect pitch fibers as basolateral long fiber yarns.

Example 5゜Prone Anu 7 Alto with a carbon content of 90.2% by weight and a quinoline soluble fraction was filled into a 4 tube 7 Lanuco, thoroughly stirred under a stream of nitrogen gas, and then kept at an internal temperature of 420°C for 6 hours. Through thermal decomposition and polycondensation, the softening point is 280℃, and the quinoline solubility is 41.
A meso-7 engineer pitch with an optically anisotropic structure of 21% was obtained. This pitch has an internal temperature of 3
The melted material is maintained at 70°C and discharged from a spinning nozzle with 56 holes with a diameter of 0.25 mb while maintaining the nozzle surface temperature at 550"C, and then passed through a focusing guide and a static eliminator at a surface speed of AO.
It was brought into contact with the rotating roller of Oml-, and then passed through a static eliminator, a take-up roller at the same surface speed, and then sucked into an air-length picker nozzle.

On the other hand, 02 of polyethylene oxide with an average molecular weight of 1200
% aqueous solution was injected into the air inlet hole of the engineered τ-sucker, sucked into the nozzle hole, and sprayed onto the surface of the north pitch fibers so that 2% of the fiber weight was deposited, and collected as a bundled yarn in the fiber gun.

Furthermore, as in Example 1, the position M directly below the air sucker nozzle
50 parts of mineral oil, methi oleate/l/xy in VC
20 parts of polyoxyethylene-polyoxypropylene block copolymer of 5 n, molecule filooO,
A dilute emulsified oil with a total solid content of 0.4% consisting of 5 parts of oleic acid jetta/-ruamine salt was sprayed onto the pitch fibers from a spray nozzle at a flow rate of 200-/-, 1% per fiber weight. The long fibrous bundled yarn was deposited at 5% and housed in a Noah Ivercouns.

In either case, the fibers obtained can be handled with a bundled, long fiber-like texture, and can be passed through a heating furnace maintained at a maximum temperature of 240'CK in the presence of air for a maximum temperature retention time of 1 hour. At the very least, it became a heat-infusible yarn, and the filament was further moved in an FC nitrogen gas atmosphere maintaining the maximum temperature of 1500°C to obtain a long carbon fiber. When the fibers were used with any oil agent, they had almost the same physical properties: fiber diameter 15 μ, tensile strength 187 /d, and tensile modulus 15,000 kQ/-.

In this Example 2, spinning was carried out without installing a discharge type static electricity remover and without applying any liquid inside the sucker or directly under the air sucker. , and it was not possible to collect pitch fibers as long filament yarns at all.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a spinning method showing an example of an embodiment of the present invention.

Claims (1)

[Scope of Claims] (1) When melt-spinning a pitch-based raw material, it is taken up through a process τ-sucker through at least two rollers and at least one static eliminator, and placed in an air sucker or an air sucker. A method for producing long-filament carbon fibers, which comprises applying a liquid to the fibers immediately after passing through the fibers to collect the fibers, subjecting them to air oxidation to make them thermally infusible, and then heating and carbonizing them in an inert gas atmosphere. (2) The method described in item 1 of the scope of patent f11i, wherein the pitch-based raw material is coal-based or petroleum-based. (5) Exception [Claim W in which the device is a corona discharge type]
The method described in Section iI. (4) The method according to claim 1, wherein the liquid is water, an aqueous oil, or a non-aqueous oil. (5) The method according to claim 1, wherein the liquid is applied by spraying. (6) Heat infusibility at 20~20°C below the softening temperature of the pitch raw material
1. The method according to claim 1, in which heating is performed without tension at a temperature higher than 150° C.; 1. (8) The method according to claim 1, wherein carbonization is performed by heating at a temperature of 900 to 2000°C.