JPH0735611B2 - Pitch-based carbon fiber continuous centrifugal spinning device with annular fiber recovery channel - Google Patents

Description

The present invention relates to a pitch-based carbon fiber centrifugal spinning apparatus.

In particular, the present invention relates to a continuous centrifugal spinning apparatus for pitch-based carbon fibers, which is provided with an annular fiber recovery channel that can be smoothly conveyed and recovered by being carried on an air flow without cutting and damaging the spun fiber yarn.

(Prior Art and Problems) Conventionally, as a centrifugal spinning device for pitch-based carbon fibers, a centrifugal spinning device in which a rotation axis of a rotary nozzle is vertical and a raw fiber yarn is discharged in a horizontal direction has been widely used.

This centrifugal spinning device spins a raw fiber yarn by discharging a melt pitch from a spinning nozzle port by a centrifugal force generated by high-speed rotation of a rotary nozzle.

At this time, if the air around the rotary nozzle does not flow smoothly, there is a necking phenomenon in which the yarn diameter of the raw fiber yarn becomes uneven in the longitudinal direction due to slack in the spinning process due to a decrease in air flow velocity, turbulence, etc. Occurs.

Further, even if the fiber raw yarn in which the necking phenomenon has occurred is infusibilized and carbonized and fired, high-strength carbon fibers cannot be obtained.

In the prior art, the control of the air flow in the spinning process is insufficient, and further, if the air blowing amount is increased to prevent the decrease of the air flow velocity, the turbulence of the air flow is likely to occur, so that the necking phenomenon occurs. Was difficult to prevent.

Therefore, the present applicant has filed Japanese Patent Application No. 60-242717 (Japanese Patent Laid-Open No. 62-242717).
No. 104922) proposes a centrifugal spinning device for pitch-based carbon fibers, which can prevent the occurrence of necking phenomenon in the spinning process.

This centrifugal spinning device is equipped with air blowing nozzles or slits above and below the outer circumference of a rotary nozzle, and further provided with upper and lower air blocking plates on its outer circumference so that the distance between the upper and lower air blocking plates becomes smaller toward the outer circumference. Is configured.

In this centrifugal spinning device, the velocity of the air blown from the air blowing nozzle or the slit into the spinning path defined by the upper and lower air blocking plates is constant or accelerated toward the outer periphery, so Necking phenomenon does not occur, because the speed is not reduced or disturbed.

Moreover, since the air blowing amount is not increased, energy is not wasted.

However, this device relates to the improvement of the spinning process, and does not improve the prior art in the process of transporting and collecting the fiber raw yarn after the spinning is completed.

The present invention is directed to the above-mentioned Japanese Patent Application No. 60-242717 (JP-A-62-104922).
No.) is used as a base,
This is an improved collection process.

In a conventionally known collecting device used in a centrifugal spinning device, a rotating collecting arm is installed around the entire circumference of a rotating nozzle or a part thereof to collect spun fibers.

The spun fiber is conveyed to the rotary collection arm by centrifugal force generated by the rotation of the rotary nozzle or air flow generated by the rotation.

The same applies to the method for conveying and collecting the pitch-based carbon fiber raw yarn.

By the way, the yarn immediately after spinning the pitch has a characteristic of extremely low strength.

For this reason, if handled by mechanical means, the fiber raw yarn may be easily cut or the surface of the fiber raw yarn may be damaged, resulting in high strength carbon even after proceeding to the infusibilization process and the carbonization process after the spinning process. The fiber cannot be manufactured.

Further, since the centrifugal force generated by the rotation of the rotary nozzle is relatively weak, the fiber raw yarn may be caught in the gap between the rotary nozzle and the heater installed below it, and the rotary nozzle may stop.

An air flow is used as a method for transporting spun fibers, and means for smoothing this air flow include, for example, JP-A-60-167908.
And JP-A-59-150106.

Japanese Patent Laid-Open No. 60-167908 discloses a device for conveying spun fibers,
Between the rotary spinning tray (rotary nozzle) and the fiber collecting means,
It is disclosed to install a "ringed air soccer".

This "ring-shaped air sucker" is composed of a pair of upper and lower "hollow air rings" having an air inlet and an air discharge slit, and is arranged concentrically with the rotary spinning tray and radially outside thereof. .

Then, the spun fibers transported by the transport air of the "ring-shaped air sucker" are collected by a container arranged outside thereof and a conventionally known collecting arm.

However, since the conveyed spun fiber is collected while colliding with the container and the collecting arm, in the case of pitch-based carbon fiber raw yarn, it is easily cut or the surface of the fiber raw yarn is damaged. Will be lost.

Further, in this device, slits inclined toward the outer side in the radial direction of the rotary spinning tray are provided on the opposite surfaces of the "hollow air ring", and the air pressure, the width and the angle of the slit of the "hollow air ring" are selected. This makes it possible to arbitrarily change the flight direction, speed, and strength of the spun fiber.

However, in the case of pitch-based carbon fiber raw yarn, if the conveying air is increased, the fiber raw yarn is severely cut and damaged in the collecting stage.

In JP-A-59-150106, in order to collect the spun yarn,
It has been proposed that the upper and lower "guide plates" be installed horizontally around the perforated cup (rotary nozzle) in the rotational direction, and the spun filaments are conveyed while being aligned in the filament axial direction by a smooth conveying air. .

Then, the conveyed spun yarn form is supplemented by a lattice-shaped wall surface provided at an outer end portion of the conveying passage defined by the "guide plate" at a substantially right angle to the passage.

Since the spun yarn-like collection according to this proposal is carried out on a lattice-like wall surface that allows free ventilation, in the case of pitch-based carbon fiber raw yarn, the collection is performed in the same manner as in JP-A-60-167908. At times, the fiber yarn is cut or damaged.

Examples of means for collecting the fiber raw yarn include, for example, JP-A-60-1731.
There is No. 10.

JP-A-60-173110 has a structure in which a fixed outer peripheral wall is provided on the outer peripheral portion of a rotary spinning tray (rotary nozzle), and the spinning fiber rotating along the fixed outer peripheral wall is collected by a collecting arm.
The feature is that the fixed outer peripheral wall is formed by punching metal.

The use of punching metal prevents heat from staying on the fixed outer peripheral wall and prevents spun fibers from adhering to the fixed outer peripheral wall.

Therefore, also in this proposal, the spun fiber collides with the fixed outer peripheral wall and then collides with the collection arm to be collected.
Cutting and damage during collection are unavoidable.

It is an object of the present invention to prevent a pitch-based carbon fiber raw yarn having extremely weak strength from being cut or damaged during the transportation / collection process.

(Means for Solving Problems) The inventors of the present invention have described the above-mentioned JP-A-60-2427 regarding the spinning process.
Based on No. 17 (Japanese Patent Laid-Open No. 62-104922), the process of feeding and collecting fiber raw yarn was improved, and cutting of pitch-based carbon fiber raw yarn at the time of feeding and collecting, which was difficult with the prior art, was difficult. , Succeeded in preventing damage.

The configuration of the present invention is as follows.

The rotation axis of the rotary nozzle is vertical and the discharge direction of the fiber raw yarn is horizontal, and air blowing nozzles or slits are provided above and below the outer circumference of the rotary nozzle, and upper and lower air blocking plates are provided on this outer circumference, and In the pitch-based carbon fiber centrifugal spinning device formed such that the distance between the upper and lower air blocking plates becomes smaller toward the outer circumference, an annular fiber recovery channel is installed over almost one circumference of the outer circumference of the air blocking plate. . The annular fiber recovery channel communicates with the spinning path defined by the upper and lower air blocking plates and has an outlet opening at one end thereof.

The cross-sectional area of the annular fiber recovery channel is formed so as to gradually increase in the direction toward the outlet opening provided at one end thereof.

Note that punching plates may be provided above and below the upper and lower air blocking plates, and the annular fiber recovery channel may be connected to the outer peripheral side end portions of the upper and lower punching plates.

Further, if a belt conveyor evacuated from the back side is arranged near the outlet opening of the annular fiber recovery channel, the fiber raw yarn can be automatically recovered in a sheet form.

(Function) The raw yarn discharged from the spinning nozzle hole of the rotary nozzle and spun into a yarn diameter of 10 to 20 microns was defined by the upper and lower air blocking plates by the air flow from the air blowing nozzle or the slit. It becomes the carbon fiber raw yarn in the spinning route.

Then, this fiber raw yarn is carried by the action of centrifugal force and the air flow in the annular fiber recovery channel formed over the outer periphery of the air-blocking plate over the entire circumference, and the outlet opening of the annular fiber recovery channel It is continuously collected from the department.

The fiber recovery channel is annular, and since the cross-sectional area is formed so as to gradually increase in the direction toward the outlet opening, the velocity of the air flow flowing in the annular fiber recovery channel becomes constant, Smooth air flow.

As a result, the fiber raw yarn is smoothly conveyed along the inner peripheral wall of the annular fiber recovery flow channel without strongly contacting the inner peripheral wall,
It can be recovered from the outlet opening of the annular fiber recovery channel, and is not cut or damaged during the transportation and recovery processes.

Further, the transport amount of the fiber raw yarn gradually increases toward the outlet opening of the annular fiber recovery channel, but since it is formed so that the cross-sectional area of the annular fiber recovery channel gradually increases, it continues smoothly. Can be transported and collected.

(Examples) Examples of the present invention will be described below, but the present invention is not limited thereto.

Embodiment 1 An explanation will be given based on FIG. 1 and FIG.

The rotary shaft of the rotary nozzle 1 (the number of nozzle holes: 100 holes) is vertical, and a spinning nozzle hole 2 is formed at the tip of the rotary nozzle 1.

The raw material pitch is discharged in the horizontal direction from the spinning nozzle hole 2 as a raw yarn.

Air blowing slits 3 and 4 are provided above and below the outer circumference of the rotary nozzle 1.

Upper and lower air blocking plates 5 and 6 are installed on the outer circumferences of the air blowing slits 3 and 4.

The distance between the air blocking plate (upper) 5 and the air blocking plate (lower) 6 is
As shown in FIG. 1, it is formed so as to become smaller toward the outer circumference.

Punching plates 8 and 9 are provided above and below the outside of the air blocking plates 5 and 6, respectively.

Then, at the outer peripheral side end portions of the upper and lower punching plates 8 and 9, the outer circumferences of the upper and lower air blocking plates 5 and 6 and the punching plates 8 and 9 are substantially circled to form an annular fiber recovery channel 10.
Is installed.

An outlet opening 11 is provided below the end of the annular fiber recovery channel 10.
Are formed.

A belt conveyor 12 is arranged below the outlet opening 11.

While introducing the heated nitrogen gas into the rotary nozzle 1,
When the raw material pitch is supplied, the temperature of the spinning nozzle hole 2 is controlled to 390 ° C., and the spinning is carried out under the condition of the number of revolutions of 3500 rpm, the raw yarn is continuously taken out from the outlet opening 11 of the annular fiber recovery channel 10. I was able to.

The obtained raw yarn was oxidized with air to make it infusible, and further carbonized at 1000 ° C. in a nitrogen atmosphere to produce carbon fiber.

The strength of this carbon fiber was 17.5 Ton / cm ² .

Comparative Example 1 By a method similar to that of JP-A-60-173110, spinning was carried out under the same temperature and number of revolutions as in Example 1, and recovered manually.

The obtained raw yarn was oxidized with air to make it infusible, and further carbonized at 1000 ° C. in a nitrogen atmosphere to produce carbon fiber.

The strength of this carbon fiber was 8.5 Ton / cm ² .

(Effects of the Invention) The present invention is capable of smoothly spinning a pitch-based carbon fiber raw yarn having excellent properties, as described in Japanese Patent Application No. 60-242717 (JP-A-62-1049).
No. 22) is a base for improving the transport and collection process of the fiber raw yarn according to the conventional technology.

According to the present invention, an annular fiber recovery flow path is installed on the outer peripheral portion of the device of Japanese Patent Application No. 60-242717 so as to make a complete circle.

Along the inner peripheral wall of the annular fiber recovery channel, the fiber raw yarn conveyed along with the air flow at a constant velocity is conveyed without making strong contact with the inner peripheral wall of the annular fiber recovery channel, and continues from the outlet opening. Then it is recovered smoothly.

Therefore, unlike the prior art, the fiber raw yarn is not cut or damaged by colliding with the collecting arm or the like.

Therefore, by using the device of the present invention, a high-strength carbon fiber raw yarn can be obtained.

Moreover, since the annular fiber recovery flow channel serves both as a transport means for the fiber raw yarn and as a collecting means, it is not necessary to separately provide a collecting arm as in the prior art.

Further, the structure is simple, and the conventional device can be easily installed without complicating it.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a pitch-based carbon fiber continuous centrifugal spinning device with a circular fiber recovery channel of the present invention. FIG. 2 is a plan view of FIG. 1 ... Rotating nozzle 2 ... Spinning nozzle hole 3 ... Air blowing slit (top) 4 ... Air blowing slit (bottom) 5 ... Air blocking plate (top) 6 ... Air blocking plate (bottom) 7 ... Straightening layer 8 …… Punching plate (top) 9 …… Punching plate (bottom) 10 …… Circular fiber recovery channel 11 …… Circular fiber recovery channel outlet opening 12 …… Belt conveyor

Claims (2)

[Claims] 1. A rotary nozzle has a vertical axis of rotation and a raw fiber yarn is discharged in a horizontal direction. Air nozzles or slits are provided above and below the outer circumference of the rotary nozzle, and the upper and lower outer circumferences of the air nozzle are provided. A pitch-based carbon fiber centrifugal spinning device in which air barrier plates are provided, and the distance between the upper and lower air barrier plates is reduced toward the outer periphery, in which the outer periphery of the air barrier plate is covered over substantially one round. Is provided,
Communicating with the space defined by the upper and lower air blocking plates,
It has an outlet opening at one end, and is provided with an annular fiber recovery channel formed so that the cross-sectional area gradually increases in the direction toward the outlet opening. Pitch-based carbon fiber continuous centrifugal spinning device with annular fiber recovery channel. 2. A punching plate is provided above and below the upper and lower air blocking plates, and an annular fiber recovery passage is connected to outer peripheral side end portions of the upper and lower punching plates. A pitch-based carbon fiber continuous centrifugal spinning device with an annular fiber recovery channel according to claim 1.