JPS591724A - Preparation of carbon fiber - Google Patents

Abstract

PURPOSE:To obtain easily filamentary carbon yarns, by melt spinning a pitch type material, applying a liquid to the resultant carbon filaments, collecting the filaments, taking off the collected filaments with two or more rolls, oxidizing the resultant filamentary yarns with air, and carbonizing the resultant heat- infusible yarns in an atmosphere of an inert gas. CONSTITUTION:A coal or petroleum type pitch raw material is melt spun, and a liquid, e.g. water, an aqueous oiling agent or nonaqueous oiling agent sprayed from a liquid spray nozzle 2, is applied directly to the resultant filaments, which are collected and passed through at least two rolls 3 and 4 and taken off by an air sucker 5. The resultant filamentary yarn is then oxidized with air, made infusible by heat, e.g. heated at 0.5-7 deg.C/min heating rate to a temperature 20- 150 deg.C higher than the softening temperature of the raw material pitch under no tension, and carbonized in an atmosphere of an inert gas preferably under heating at 900-1,300 deg.C to give the aimed filamentary carbon yarn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing long carbon fibers.

In the past, pitches were consumed as starting materials for coke and carbon materials, and it was devised to use this raw material to produce carbon fibers, which are now being produced industrially. Gradual fibers can be roughly divided into two methods: one is made from acrylonitrile-based synthetic IAM, and the other is made from melt-spun pitch-based raw materials. The manufacturing process involves continuous processing of endless fibers, and the standard shape of the product is that of long fibers. On the face of it, pitch-based carbon fibers are in the form of so-called chopped 7A I/<- (short fibers), or they are fiber products processed into AT material, such as already twisted yarn, felt, cloth, paper, etc. As a product that is aligned in the longitudinal direction, it is at best a sliver shape. This is because when melt-spinning pitch-based raw materials to obtain yarn for carbon fibers, the temperature dependence of the melt viscosity of the raw materials is too steep, so the safe operating temperature range without yarn breakage during spinning changes. Due to narrow, slight temperature control irregularities, or factors such as unavoidable fluctuations in the spinning work area, such as minute changes in air flow, there is a risk of yarn slipping, and therefore, actual removal of acrylonitrile It is difficult to collect long fibers in an endless state, such as synthetic fibers produced by melt spinning, such as nylon and polyester fibers. 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, even though it is desired to produce carbon fibers in the form of long fibers, the reality is that carbon fibers are often produced in the form of short fibers. The most common manufacturing method currently in use is to turn the pitch-based raw material discharged from a spinning nozzle in a molten state into fibers and wind it onto the rotating bobbin E, but as mentioned above, the raw yarn itself is fragile. Unable to make the so-called original paper, the thread is rolled thinly and then the bobbin is put away as appropriate.The resulting thinly wound raw yarn is cut into two parts, for example, to form a sliver, and then the thread is rolled in a normal pitch type. After undergoing infusibility treatment through so-called heating oxidation, which is carried out in the carbon fiber manufacturing process, carbonization treatment is performed in an inert gas atmosphere, and the fibers are cut to the desired fiber length to produce products. If at all, the chopping step to produce this final product is carried out before or after infusibility.

Pitch-based carbon fibers can be broadly divided into low-strength, low-elasticity so-called low grade, and high-strength, high-elasticity Noi-blade.
The latter is made using Menface's liquid crystal spinning method.

If a final product can be obtained in the form of any type of co-attached filament, it will greatly contribute to expanding the range of uses and eliminating waste by increasing product yield in the manufacturing process. For example, in the field of asbestos substitute materials, which have a large potential demand for low-grade products, and their use in vehicle structural materials, especially automobiles, if roving, which is a typical product form of glass fiber, can be produced, it would be possible to improve the manufacturing process. Not only will it be more rational, but it will also be possible to use a wide range of processing techniques that utilize all pitch-based carbon fibers.

The present inventors completed the present invention as a result of research aimed at obtaining long-fiber carbon edge l# from pitch-based raw materials.

The purpose of the present invention is to form long-fiber carbon fibers. It is to offer. Another object of the present invention is to provide a method for industrially and easily manufacturing fibers such as #-1Pfr.

In the method of the present invention, immediately after melt-spinning pitch-based raw materials, a liquid is applied to the pitch-based raw materials to make them converge, and the threads taken through an air sucker through at least two rollers are oxidized in the air to make them thermally infusible, and then placed in an inert gas atmosphere. The entire feature is that it is heated and carbonized.

Pitch-based raw materials that can be applied to the present invention include not only the black carbonaceous solid residue obtained when blackening the cool obtained from an organic material such as coal, but also 13
Examples include solids purified by solvent during lime liquefaction process or tar extraction process called 1c, and heat-treated products of petroleum asphalt.

In melt-spinning pitch-based raw materials, the spun yarn is fragile and cannot be wound thickly onto a bobbin like the usual melt-spinning synthetic fibers. It is passed through an air sucker through two rollers and stored in a 7-inch cup.The typical material used for the Ro 2 used here is metal Roku with a mirror finish or satin finish, but the surface is covered with rubber and the sides are It is also possible to use Ilb-lined products.It is usually preferable to install one roller below the spinneret in a vertical line, and position the other rollers as appropriate depending on the working situation. On the other hand, one of the other rollers is used for picking up and storing it in the fiber dancer.The 7-eye parkance is made of a perforated cylinder and may be rotated eccentrically on the floor as necessary. be.

The pitch base material P1#-i is hydrophobic due to its constituent components, and the raw yarn discharged by melting it does not exhibit moisture or water absorption at all. Therefore, in the process of passing through at least two rollers and an air sacker after leaving the spinning nozzle, the fibers generate a considerable amount of static electricity due to the running contact between the fibers and other materials. If you continue to work in that charged state, it will get wrapped around the rollers and cause fiber breakage, and even if you can deliver it to 71 Ipercence via an air sucker, you will not be able to collect it as a fiber bundle. , each of the 41 fibers becomes entangled and becomes the following]1
It is completely impossible to transfer the fibers in the form of threads.

In order to remove static electricity and focus the filaments, oiling methods such as those used in conventional synthetic fibers, such as bringing the running fiber into contact with the surface of a rotating roller with an oil film on the surface, are used to remove the spinning material. Xiaomi does not use it because the thread is extremely fragile. Due to the resistance that the spun yarn receives when it passes through layers made of various oil agents, stress is transmitted to most of the yarn t directly below the spinning nozzle, and most of the filaments are broken at that point.

However, in the method of the present invention, water, a water-based oil, and also a non-aqueous oil are sprayed along the running direction of the #i yarn, from the spinning nozzle side in the 10-2- direction, so that the yarn is not cut. Instead, the filaments of the macro-multiple tree are focused by the adhesion of the liquid. The phenomenon of lint occurs when the fiber surface is simply knitted without the pitch fiber absorbing these liquids at all due to its woody nature.
By attracting each other and converging. As a result, it is stored in the 71 IPerguns through the air sucker through the 1st to 20th rollers in a wet state, so if water, water-based oil, or non-aqueous oil containing an antistatic agent is used, the fibers and No static electricity is generated due to running contact with other materials, and the long fiber state remains focused. In this case, the liquid is of course supplied by spraying from a spray nozzle, but it is also called a lubrication nozzle that forms a thin film of liquid in a certain area of the V-shaped recess, and the inside of the film is used to feed the spinning raw material. Although it is possible to use the fiber table 111J1 depending on the method by which the thread penetrates, the spraying method is most suitable.

The raw yarn wetted with liquid is shaken considerably while passing through at least two rotating rollers and the air thermal force, and although the liquid itself may spill into the space, the liquid is still is stored in the 71 Ipercence with several layers on the fiber surface. Since this yarn is hydrophobic, there is no deterioration in the physical properties of the fiber due to twisting. The raw yarn stored in IL4 is then held for a while without applying any tension.
When moving to the next step, which is thermal infusibility treatment by heating oxidation, the liquid attached to the surface of the fiber 81 causes an outer layer to be removed from the raw yarn.
Selection of liquid type and liquid adhesion, *f: must be controlled so that acid finish supply from x++ is not obstructed,
No matter what kind of liquid is used, it is not impossible to make it thermally infusible, and since a VC difference will occur to that extent, the oxidation conditions should be adjusted accordingly. Basically, it vaporizes and disappears in the heating infusibility process, or
Alternatively, it is preferable to carry out thermal decomposition and vaporization at as low a temperature as possible. To that extent, it is most ideal to use water alone, but most of the attached water is multiplied by the air jetted through the air sucker, and this may occur if the stored long fibers do not have sufficient cohesiveness. . In that case, an aqueous oil agent or a non-aqueous oil agent is used, and the former includes mineral oil (Red Hood 100 seconds or less), ethylene oxide adduct of higher alcohol,
Higher alcohol phosphate ester salts, alkyl esters of fatty acids (higher alcohols, higher fatty acids are charcoal: A number of 12 to 18, such as cucryl, cetyl, stearyl, oleyl, etc.) as appropriate. A typical oil agent is a mixture of selected Ik compounds mixed with water.
A known substance known as an antistatic agent for synthetic fibers may be added to this. In this case, the oil component concentration #''i is preferably 50% by weight or more F%, particularly 20% or less.

Zero Hatsuri 1 does not contain metal ions. Furthermore, a water-based oil agent that does not contain high-temperature decomposable organic compounds is obtained, which is optimal in that it does not impair the physical properties of carbon fibers.As a non-aqueous oil agent, mineral oil (with a V-temperature of 100 seconds or less) alone and synthetic fibers can be used. It can also be used by mixing and dissolving it in antistatic agent 1, which is known for commercial use.

If the Red Hood number of the mineral oil is 100 seconds or more, the liquid viscosity is high, so the resistance that the raw yarn receives during running increases, and yarn breakage is likely to occur during spinning, so a temperature of 80 seconds or more is particularly preferable.

When using any liquid, the amount of adhesion varies depending on the composition of the liquid, but in the case of water alone, it is 2 to 5 times, M%.
In the case of water-based oil agents, the range is preferably 1 to 4%, and in the case of non-aqueous IFI agents, the range is preferably 2 to 2%, regardless of whether the liquid is supplied using a cloth or injection nozzle. Adjust the amount of liquid sprayed and the supply m of one nozzle so that the amount of adhesion is within the above range.

An example of spinning and drawing in 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 housed in a spinning device, and the raw material pitch is heated and melted and discharged into the air from this nozzle at a spinning speed of 1110 to +500 m.
/- to spin. 2 is a liquid spray nozzle, 3 is a take-up roller, 4 is a final take-off row 1-15i, T air sucker, 6 is a cylindrical 7-eye percanth, 7Fi static electricity remover, and 8 is a stored long fiber raw yarn. Show each.

2 is used to apply liquid to the running fibers discharged from the nozzle, and the liquid is guided to the rotating rollers in 3.4, and 1 is subtracted by the air sunker in 5, and stored in 6. Ru. In this case, the air sucker to be used is appropriately selected according to the total number of yarns, the spinning speed, its suction hole diameter, length, etc., and the compressed air pressure, air volume, etc. for the air sucker are also selected as appropriate. Is the thread material air sucker in this process? 6) It is possible to install a static electricity eliminator ff shown at 7 after exiting, or after exiting the writer's board 1, to contain and eliminate the static electricity 1 that has been positively charged.

In this way, the desired amount of the long fiber raw yarn 8 stored in the 7-eyeperdance 6 is secured, and the end yarn is transferred onto a mesh or perforated plate, and then moved in a heated atmosphere where air is present. Therefore, by proceeding with oxidation from the surface of the filament filament, it is eventually changed to a heat-infusible state.

Thermal infusibility is achieved by passing the long fibrous yarn in a heated atmosphere in the presence of air onto a prickly or perforated metal conveyor in a single layer without overlapping the yarns for more than 2N and loosely. Place it under tension-free condition and move it. The temperature gradient during the movement is set at 0.5-b, and the temperature is reached 20-15 degrees higher than the softening temperature of the raw material pitch, and furthermore, within the maximum temperature range, 5-5 degrees higher than the softening temperature of the raw pitch.
It will be moved for 60 minutes.

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

After the infusibility treatment, the filamentous filament is introduced into a heating chamber under an inert gas atmosphere, where it is heated and carbonized to form a filamentous filament. In the case of knit, the movement of the long edge weft threads is possible either under no tension or under tension, and the temperature gradient during the transfer is 3 to 20 degrees Celsius above room temperature, with a maximum temperature of 900 to 1600 degrees Celsius. It is moved under conditions where the holding time is 5 to 30 minutes, and carbonization treatment is performed. The treated fibers are carbon fibers with sufficient tensile strength, which can be wound into rovings, for example, in accordance with conventional w&fiber handling methods.

The present invention focuses each single fiber by applying liquid to the surface of the spun yarn, which is made brittle and has no heat absorption or water absorption properties.
As a result, we avoided the problem of yarn breakage during the running of spun fibers, and by carbonizing the yarn collected in the form of long fibers without winding the yarn on homogeneous VC using the forced suction effect of a single gas flow, we were able to avoid the problem of yarn breakage when the spun fiber runs. This method enables the production of long-fiber carbon fibers that could not be obtained from raw materials, and has a wide range of applications.

Although it will be specifically explained below in Examples, the zero starting point j is limited to this.

*Male side 1゜Coal tar pitch with average molecular weight 600 and softening point 220℃ Filled in a full vessel type Merck, heated from the outside under nitrogen gas to bring the internal temperature to 250℃, and melted coal cool pitch using a gear pump. Quantitative liquid delivery / pore diameter 0.5
The yarn was discharged from a spinning nozzle with 62 holes and introduced into an air sucker via two rollers rotating at a surface speed of 300 m/wk.

Pour 500 d of tap water at room temperature on the roller directly below the nozzle.
The spun yarn was sprayed from a spray nozzle at a flow rate of /-, and the surface of the yarn was moistened with 4% of the fiber layer. The fibrous yarn was made up of 8 pieces and stored in a 7-eye space. After 60 minutes of spinning (continuation time), the continuous yarn is cut and the end yarns are placed in a heating furnace maintained at a maximum temperature of 500°C. I passed it. In this case, the yarn transfer temperature gradient is
/-, the holding time at 300°C was set to 20 minutes ◇The yarn taken from the heating furnace remained in an infusible state even when exposed to a flame trap. This infusible yarn was also placed in a 7-eye container, and then the 7 yarn end yarns 1-* were guided and placed on a stainless wire mesh without tension, and the center temperature was 1000°C and nitrogen gas was applied. The raw gold was moved in an electric furnace. In this case, temperature gradient is 5℃/return, maximum temperature is 1000℃
The long fibrous yarn was carbonized under conditions such that it remained open for 10 minutes when held. In this way, long-fiber carbon fibers were collected using coal cool pitch as a raw material. The physical properties of this fiber are a fiber diameter of 16μ, a tensile strength of 730 kli/d, and a tensile modulus of 2.
It was 900kQ/-.

As a comparative experiment, spinning was carried out under the same conditions except that the tap water was not completely removed from the fumarole, and the yarn wound around the rotating roller just below the nozzle, and for a while, most of the gold yarn was cut off at the nozzle discharge surface, resulting in a long fiber-like raw yarn. O could not be detected Example 2 Solvent-refined coal (abbreviated as EIR (!) with an average molecular track of 800 and a softening point of 245°C was charged into the same spinning device as in Example 1, and the inner atmosphere under nitrogen was heated to 270°C. and melted 11,25 m
Discharge from a nozzle with 28 diameter holes, surface speed 50
0? ? The air sucker IC was guided through two rollers rotating at 1/-.

Note 1) A II nozzle is installed between the nozzle and the 10th roller,
By injecting mineral oil (Red Hood 40 seconds) 41 into the V-shaped slit installed in it, an oil film is formed by injecting mineral oil (Red Hood 40 seconds) from the nozzle pore, and the spun raw yarn is passed through the oil film to be applied to the surface based on the weight of the fiber. One part of 91% of the adhesion was applied, passed through a single rotation roller, and sucked into an air sucker having the same shape as in Example 1. At the exit of the air sucker, a corona discharge type static electricity eliminator (Eliminostat manufactured by Shishido Kyukai Co., Ltd.) was installed. )1?R
After the static electricity charged on the long fiber yarn was removed, it was stored in a fiber cage. The floated m-fibers were bundled with oil IW1, which was scooped out for each single fiber, and in that state, it was possible to hold and transfer the fibers.

The stored long fiber yarn 1 was first moved in the same manner as in Example 1. When heated to a maximum temperature of 270℃ in air, Koui Iima's glue became infusible, and furthermore, the maximum temperature was 950℃.
When carbonized at ℃, the fiber diameter was 14μ and the tensile strength was 72.
Long fibrous carbon fibers with a CQ/d and a tensile modulus of 2500/- were obtained.

In this case, when we did not install a discharge-type electrostatic dehulling machine and used only an oil to remove the spinning yarn, there was no problem with the yarn getting wrapped around the rotating roller. The long fibrous yarn was handled violently on the riverboat due to the turbulence of the W yarn attachment.

In fact, four O7:7 tubes were filled with blown asphalt at a temperature of 3° softened A + 5°C, and while the internal temperature was maintained at 280°C, nitrogen gas was blown in and the low boiling point fraction was distilled off, and the carbon content was reduced to 87. 49
5 with a softening point of 185°C 74)' Sfaldo pitch was cut out and heated to an internal temperature of 260°C using the same spinning device as in Example 1.
While holding the water at Hood 40 seconds
++ζ, secondary acid methyl ester 4571 (,9FM
+000 polyoxyethylene-polyoxyglobylene block copolymer 20 parts, oleic acid jetanolamine salt 5 parts total solid content 15 parts, water 100 weight M,
2. Apply the emulsified oil to the low temperature directly below the nozzle.
00m$/- was sprayed from a spray nozzle toward the spun raw yarn, and with the surface of the raw yarn moistened by 1.5% per fiber weight, using an air sucker with the same shape as in Example 1. The mixture was vacuumed and stored in a 1-in-1 can as a long fibrous yarn.

The obtained woven fabric #a is a bundled long fiber yarn that can be handled, and a heat-infusible yarn can be obtained by passing it through a heating furnace maintained at a maximum temperature of 250°C in the presence of air. Fibrous carbon fibers with a fiber diameter of 12μ and a tensile strength of Strength 9
It had physical properties of 0kQ/-1 and tensile modulus of 3200k ('/-).

In this 194 example, when the emulsified oil was not sprayed, the spun yarn wound around two rollers, causing single yarn ν) to curl on the nozzle surface, and the number of yarn breaks gradually increased. The number of long fibers continued to increase, making it impossible to collect long fibers. .

[Brief explanation of the drawing]

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

Claims (1)

[Scope of Claims] (1) Immediately after melt-spinning pitch-based raw materials, a liquid is applied to the pitch-based raw materials to make them converge, and the pitch-based raw materials are spun by air through at least two rollers.
- A method for producing a long-fiber carbon woven material, which comprises air-oxidizing the yarn taken through a sucker, making it infusible by heat, and then carbonizing it by heating in an inert gas atmosphere. (2) The method according to claim 1, wherein the pitch-based raw material is coal-based or petroleum-based. (6) The method according to claim 1, wherein the liquid is water, aqueous oil, or Fi non-aqueous oil. (4) The method according to claim 1, wherein the method is applied using a liquid tvtuit. (5) Thermal infusibility is 20 to 20 degrees higher than the softening temperature of the pitch raw material.
Heating without tension at a temperature 150℃ higher! F#Irf The method according to claim 1. (6) The method according to claim 1, wherein thermal infusibility is 0.5 to b. (7) Heating carbonization at a temperature of 900-1600℃ 7
A method according to claims gsI.