JPS63303121A - Production of high-strength and high-modulus carbon fiber and spinneret therefor - Google Patents

Abstract

PURPOSE:To obtain the titled carbon fiber with the sectional orientation controlled so as to be random, by spinning molten pitch using a spinneret where the nozzle introduction part of larger diameter of the spinning nozzle is laminated with thin-layer filter(s) so as to be located just in front of the nozzle part of smaller diameter. CONSTITUTION:The objective carbon fiber can be obtained by spinning molten pitch using a spinneret where the nozzle introduction part of larger diameter 15a of the spinning nozzle is laminated with thin-layer filter(s) 16 so as to be located just in front of the nozzle part of smaller diameter 15b. The outer diameter of said filter 16 is made to be similar to the inner diameter of the nozzle introduction part of larger diameter 15a. Furthermore, the thickness of said filter 16 is made to be 3-300mum.

Description

DETAILED DESCRIPTION OF THE INVENTION - No. 1 The present invention provides carbon edge #I (from pitch to high strength and high modulus of elasticity)
In this specification, the term "carbon fiber" is used to include graphite fiber. ), in more detail,
The present invention relates to a spinneret with an improved structure and a method for producing high strength, high modulus carbon fibers including spinning molten pitch using the spinneret.

In recent years, lightweight, high-strength, high-modulus carbon fibers have been developed and used in various technical fields. In order to produce carbon fibers, molten pitch is usually spun into pitch fibers by forcing it into a spinning nozzle under pressure, and the pitch fibers are made infusible, carbonized, and graphitized to achieve high strength and high elasticity. It is made of carbon fiber.

Conventionally, it has been known that in order to obtain carbon fibers with high strength and high elastic modulus, it is important to control the cross-sectional orientation/axial orientation of the fibers and to produce carbon fibers with a random cross-sectional orientation. There is. The cross-sectional orientation of carbon fibers is determined when spinning pitch fibers, and for this purpose, the structure of the spinneret has been studied, and a porous body is placed in the spinning nozzle formed in the spinneret upstream and away from the entrance of the spinning nozzle hole. A method of inserting a spinning nozzle or providing an insert having a spiral groove in the spinning nozzle hole has been proposed (Japanese Patent Laid-Open No. 59-88909, Japanese Patent Laid-Open No. 61
-201021, JP-A-60-259609, etc.).

Although this method allows for a certain degree of orientation control,
It is still not satisfactory, and there are problems in terms of reproducibility and practical application. In particular, with these methods, when multiple nozzles are used, not only is manufacturing complicated and expensive, and maintenance such as cleaning is difficult, but it is also difficult to make the flow path resistance between the nozzles the same. This results in uneven thread diameter between nozzles, which poses problems in terms of reproducibility and practical application. Therefore, there is a need in the art for a manufacturing method and a spinneret that can be easily and reliably carried out industrially.

In order to solve the above problem, the present inventors, in the process of researching the pitch fiber spinning method and the structure of the spinneret,
By inserting a precisely shaped thin layer filter into the spinning nozzle and spinning, the cross-sectional orientation/axial orientation of the fibers can be easily controlled, and in particular, the cross-sectional orientation can be extremely easily controlled to have a random structure. , and found that the pressure drop during spinning due to filter insertion is significantly reduced.

Furthermore, it has been found that by reducing the pressure drop, the frequency of yarn breakage is reduced, there is no variation in yarn diameter, and no variation is observed in the physical properties, and stable spinning can be achieved.

Furthermore, the present inventors have created a fiber with a thickness of 3 to 300 mm by placing it in the spinning nozzle just before the small diameter nozzle part. At least one am thin layer filter is laminated with a thickness of 0.5 mm or less, the molten pitch is guided from the large diameter nozzle introduction part to the small diameter nozzle part via the thin film filter, and then the small diameter By pushing it into the nozzle part, the temperature drop, especially the pressure drop, can be kept to the minimum, and the yarn is less likely to break, there is no variation in the yarn diameter, and there is no variation in its physical properties, resulting in stable spinning. L! The present invention has been made based on this new knowledge.

One L1 unit The object of the present invention is to provide fibers with a random cross-sectional orientation,
It is an object of the present invention to provide a manufacturing method and a spinneret for manufacturing high-strength, high-modulus carbon fibers that do not generate cracks during firing and have stable physical properties.

Other objects of the present invention are to be able to perform stable spinning, to easily control the yarn diameter, to be able to spin a pitch am with a small yarn diameter at high speed, and to be able to spin carbon ta, m with high strength and high elastic modulus. An object of the present invention is to provide a manufacturing method and a spinneret for manufacturing the invention.

Another object of the present invention is to provide a manufacturing method and a spinneret for manufacturing high-strength, high-modulus carbon fiber that can be extremely easily spun using multiple nozzles.

The above aspects are achieved by the manufacturing method and spinneret for manufacturing high-strength, high-modulus carbon fibers according to the present invention. To summarize, the present invention provides a spinneret having at least one spinning nozzle having at least a large-diameter nozzle introduction part and a small-diameter nozzle part formed in communication with the nozzle introduction part.

The large-diameter nozzle introduction part of the spinning nozzle has a thickness of 3 to 300 A so as to be located immediately in front of the small-diameter nozzle part.
At least one m thin layer filter.

Laminated with a thickness of 0.5 mm or less, the molten pitch is guided from the large diameter nozzle introduction part to the small diameter nozzle part via an 8-layer filter, and then spun by being pushed into the small diameter nozzle part, This is a method for producing high-strength, high-modulus carbon fiber, which is characterized by performing infusibility treatment and carbonization treatment, and further performing graphitization treatment as necessary. Preferably, the pressure drop across the laminar filter is between 0 and 10 kg/cm.

According to another aspect of the present invention, there is provided a spinneret for spinning pitch fibers by feeding molten pitch under pressure, the spinneret comprising at least a large-diameter nozzle introduction section and a nozzle introduction section communicating with the nozzle introduction section. at least one spinning nozzle having a small-diameter nozzle portion formed by a spinning nozzle, and a large-diameter nozzle introducing portion of the spinning nozzle has a thickness of 3. There is provided a spinneret characterized in that at least one thin-layer filter having a thickness of 0.5 mm or less is laminated with a thickness of 0.5 mm or less.

191 cases Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view showing a specific example of a pitch fiber spinning apparatus d used to carry out the method of the present invention.

This spinning apparatus Hto includes a heating cylinder 12 into which molten pitch (especially optically anisotropic pitch) 11 is injected from a pitch pipe (not shown), and a plunger 13 that pressurizes the pitch within the shilling 12. , and a spinneret 14 attached to the bottom side of the heating cylinder 12. The spinneret 14 has one or more spinning nozzles 15 formed therein, and is configured by being removably fixed to the lower side of the heating cylinder 12 with a port 17 and a spinneret holder 18. After passing through the spinning tube 19, the spun pitch fibers are wound onto a winding bobbin 20.

In the method of the present invention, by improving the structure of the spinneret in such a spinning device, in other words, at least one thin layer filter 16 with a thickness of 3 to 300 μm is installed in the spinning nozzle 15, and a thin layer filter 16 with a thickness of 0.5 mm or less is installed in the spinning nozzle 15. By laminating the molten pitch and spinning the molten pitch through the thin layer filter, the temperature drop and especially the pressure drop when the molten pitch 11 passes through the spinning nozzle 15 are suppressed to the minimum, and the physical properties of the fiber, In particular, it prevents variations in yarn diameter and fiber cross-sectional orientation.

To explain in more detail about the spinneret 14 used to carry out the method of the present invention, one embodiment is shown in FIG. 2. According to this embodiment, the spinneret 14 has at least Large diameter nozzle introduction part 15a
and a small-diameter nozzle portion 15b formed in communication with the nozzle introducing portion 15a. Usually, the spinning rod 14 is made of stainless steel, such as 5US304.5US316, and the thickness of the spinning nozzle 15 T) is 2-20mm
(for example, 5 mm), with a large diameter nozzle introduction part 1
5a and the length Tl of the small diameter nozzle part 15b) and (T
2) are each 1 = 18 mm (for example, lf4.
35mm) and 0.5-2mm (e.g. '0.65mm
), and the diameters (Dl) and (D2) of the large-diameter nozzle introduction part 15a and the small-diameter nozzle part 15b are 0.5 to 5 mm (for example, 3 mm) and 0.1 to 0.5 m, respectively.
m (for example, 0.3 mm).Of course, the cross-sectional shape of the nozzle portion 15b in particular may be a polygonal shape such as a star shape, a square shape, a rectangular shape such as a rectangle, etc. in addition to a perfect circle. Further, although only one spinning nozzle 15 is shown in the drawing, a plurality of spinning nozzles 15 may be arranged in a ring shape to form a multi-nozzle, for example.

According to the present invention, the nozzle introduction section 15a includes the nozzle section 1.
A thin layer filter 16 is placed immediately in front of the filter 5b. The outer shape of the thin layer filter 16 is approximately the same as the inner diameter of the large-diameter nozzle introduction part in order to provide mechanical strength. or,
The thin layer filter 16 is a thin layer filter with a thickness of 5 to 200 m, and the thin layer filter 1
6 can be provided by laminating a plurality of sheets. In the case of a plurality of 81 layers, a suitable spacer, for example, an annular ring with a thickness of 30 A m, may be interposed between each filter. Usually, the thin layer filter is as shown in FIG. , one hole with a diameter of 5 to 200) t m (single pore material)
Or, it is assumed that a large number of holes (porous body) are formed. The shape of the hole may be a perfect circle as shown in the figure, but it can also be a non-perfect circle shape such as a star shape or a polygon. Furthermore, when a plurality of sheets are laminated, the total thickness must be 0.5 mm or less. If the thickness exceeds 0.5 mm, the pressure drop will become large, as will be explained in detail later, which is undesirable.
Furthermore, when stacking a plurality of thin-layer filters, the same filters can be stacked on top of each other, but for example, as shown in FIG. It is also possible to stack adjacent thin-layer filters such that the holes partially or completely overlap, thereby forming a curved molten pitch path in the thin-layer filter layer.

In the above description, the thin layer filter 16 is a single-pore or porous filter, but as shown in FIG.
Instead of holes, it is also possible to form elongated slits with a convergence of 5 to 100 μm and a length of lOβm to 3 mm, or a slit-like pattern having a desired shape, such as a bow tie shape, as shown in FIG. It is also possible to form When such a thin layer filter with a slit-like pattern is used, as shown in FIG. By overlapping them with slightly different relative positions, it is possible to form a meandering molten pitch path in a plurality of thin filter layers.

Although the thin layer filter can be manufactured by various methods such as laser scribing, it can be manufactured suitably and at low cost by using photolithography and electroforming techniques. That is, for example, a photoresist layer is formed on a metal plate such as a stainless steel plate, and a hole of a desired shape (single hole, An original plate (electromold) having a pattern consisting of concave portions and convex portions, which is a porous or slit-like pattern, is produced.Next, the electroform is used to produce a thin metal film by electroforming technology. That is, the four parts of the electrical mold are filled with a nonconductor, and electrodeposited metal is formed at an appropriate thickness only on the surfaces of the convex parts by the same method as electroplating. Thereafter, the electrodeposited metal on the surface of the convex portion is separated from the electrode mold. The thin layer of electrodeposited metal becomes a thin layer filter. In addition to stainless steel, thin-layer filters can be made of copper, aluminum, silver, nickel, tungsten, chrome, or brass.

According to the present invention, molten pitch is spun using the spinneret as described above. According to the present invention, when the molten pitch passes through the spinning nozzle formed in the spinneret, it is passed through a thin layer filter. Therefore, the temperature drop when passing through the spinning nozzle is suppressed to the minimum level (3° C. or less), and the pressure drop is kept to 10 kg/cm 2 or less. As a result, the frequency of thread breakage is low, there is no variation in thread diameter, and there is no variation in its physical properties.

According to the present invention, stable spinning is achieved.
The pitch m fibers thus obtained are made infusible and then carbonized or graphitized to convert them into carbon fibers (or graphite am). The methods and conditions for such infusibility, carbonization, or graphitization are well known, and their explanation will be omitted.

Color/Gloss Difference Section When spinning using the method and spinneret structure of the present invention, the following effects were achieved compared to conventional spinning methods.

(1) There is no yarn breakage during spinning of Pisen HIi fiber,
Stable spinning became possible over a long period of time (total pitch amount).

(2) The yarn diameter was stabilized, and therefore pitch fibers with stable physical properties were obtained.

(3) The orientation of the cross-section of the fibers was also stable, resulting in a random structure, and no cracks occurred during firing.

(4) Therefore, the physical properties of carbon 1ata were improved in both strength and elastic modulus.

(5) Even when spinning with multiple nozzles, the spinning operation is easy and good spinning can be achieved without unevenness in yarn diameter between each nozzle.

The present invention will be described in more detail below using examples.
The present invention is not limited to these in any way.

Example 1 A spinneret 14 having the configuration shown in Fig. T52 was attached to the plunger spinning device shown in Fig. 1, and molten pitch was spun at a winding speed of 500 m/min. The spinneret 14 is made of stainless steel (SUS3Q4), and the spinning nozzle 1
The thickness T) of the 5 part is 5 mm, and the length T1 of the large diameter nozzle introduction part 1.5a and the small diameter nozzle part 15b.
) and (T2) are 4.35mm and 0.65m respectively
It was set as m. Further, the diameters (Dl) and (D2) of the large-diameter nozzle introduction section 15a and the small-diameter nozzle section 15b were set to 3 mm and 0.3 mm, respectively. One thin layer filter was placed in the nozzle introduction section.

The 8-layer filter used in this example was manufactured using photolithography and electroforming, and was made of stainless steel (SUS 304
), it had a thickness of 30.4 m and a diameter of 3.0 mm, and as shown in FIG. 3, it had many pores with a diameter of 40 m, and the porosity was 50%.

The pitch used was an optically anisotropic (98%) pitch containing a softening point of 265° C.2 and a quinoline solubility of 29.5Qj1%.

The spinneret temperature was 320°C and the pitch temperature was 320°C, but the pressure drop before and after the thin layer filter was 0.2k.
g/crrf. No yarn breakage occurred over a long period of about 1 hour (total pitch tensioning! i1), and fibers with a stable yarn diameter were obtained. Moreover, the cross-sectional orientation of the obtained pitch fibers had a random structure. The pitch fiber was heated to 1500℃
Characteristics of carbon fiber obtained by carbonization (average of 17 samples)
were as shown in Table 1.

Example 2 The thin layer filter used in this example was manufactured by photolithography and
Manufactured using iltM processing, made of molybdenum with a thickness of 30 mm,
um, and the diameter was 3.0 mm. The filter had a single slit of 101 m x 5001 m as shown in FIG. 4.

Spinning was performed using the same spinneret as in Example 1, the same operation, and the same pitch. No yarn breakage occurred over the 0-turn time, and fibers with a stable yarn diameter were obtained. The spinnability was good, and the pitch fibers had a random cross-sectional orientation.

The properties (average of 17 samples) of the carbon fibers obtained by carbonizing the pitch fibers at 1500° C. were as shown in Table 1.

Example 3 Five thin-layer filters having the shape shown in FIG.
As shown in FIG. 6, spinning was carried out in the same manner as in Example 2, except that the layers were stacked at slightly different positions and placed in the nozzle introduction section, using the same pitch. Thin layer filter 16
The area of the triangular hole lea is 1 mrn', and the short side a
was 1 mm, and the long side was 1.1 mm.

Fibers with stable yarn diameter were obtained without yarn breakage over a long period of time. The spinnability was good, and the pitch fibers had a random cross-sectional orientation.

The properties (average of 17 samples) of the carbon fibers obtained by carbonizing the pitch fibers at 1500° C. were as shown in Table 1.

Example 4 Using a spinneret having a spinning nozzle with lOO holes having the same structure as in Example 1, spinning was carried out in the same manner as in Example 1 using the same pitch.

Fibers with stable yarn diameter were obtained without yarn breakage over a long period of time. In particular, variations in spinnability and orientation in the radial direction of the spinneret were reduced, and the cross-sectional orientation of the m-pitch fibers had a random structure.

Comparative Example 1 Spinning was carried out in the same manner as in Example 1 using the same pitch without disposing the 9-layer filter 16 in the spinneret 14 of Example 1.

The results are shown in Table 1. Yarn breakage occurred twice for about 710 minutes, the spinnability was inferior to Examples 1 to 4, the pitch fiber orientation was a radial structure, and the physical properties after firing were similar to those of Examples 1 to 4. 1
It was lower than ~4.

Table 1 Spinnability thread cutting frequency Tensile strength Tensile modulus/10 minutes Cross-sectional orientation GPa GPa Example 1 O random 3.0 240 Example 2 0 Random 2.9 230 Example 3 0 Random 3.2 235 Example 4 0 Random 3.1 240 Comparative Example 1 2 Radial 2.4 215

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a pitch fiber spinning apparatus for implementing the carbon fiber manufacturing method according to the present invention. FIG. 2 is a partial cross-sectional view of one embodiment of a spinneret according to the present invention. 3, 4 and 5 are plan views of embodiments of zero-layer filters. 6 and 7 are perspective views of embodiments of laminated thin-layer filters. 14: Spinneret 15: Spinning nozzle 15a: Nozzle introduction section 15b: Nozzle section 16: Thin layer filter

Claims (1)

[Scope of Claims] 1) A spinneret having at least one spinning nozzle having at least a large-diameter nozzle introduction part and a small-diameter nozzle part formed in communication with the nozzle introduction part is arranged, At least one thin-layer filter with a thickness of 3 to 300 μm is laminated to the large-diameter nozzle introduction part of the spinning nozzle so as to be located immediately before the small-diameter nozzle part, and the thickness is 0.5 mm or less. The pitch is guided from the large-diameter nozzle introduction part to the small-diameter nozzle part through a thin layer filter, and then spun by being pushed into the small-diameter nozzle part, subjected to infusibility treatment and carbonization treatment, and further as necessary. A method for producing high-strength, high-modulus carbon fiber, characterized by performing graphitization treatment. 2) Pressure drop before and after thin layer filter is 0-10kg/c
The method according to claim 1, wherein m^2. 3) A spinneret for feeding molten pitch under pressure to spin pitch fibers, the spinneret comprising at least a large-diameter nozzle introduction section and a small-diameter nozzle section formed in communication with the nozzle introduction section. at least one spinning nozzle having a thickness of 3 to 300 μm, and a large-diameter nozzle introducing portion of the spinning nozzle is located immediately in front of the small-diameter nozzle portion.
1. A spinneret characterized in that at least one thin-layer filter of m thickness is laminated with a thickness of 0.5 mm or less. 4) The inner diameter of the large diameter nozzle introduction part is 0.5 to 5 mm, the inner diameter of the nozzle part is 0.1 to 0.5 mm, and the outer shape of the thin layer filter is approximately the same as the inner diameter of the large diameter nozzle introduction part. A spinneret according to claim 3. 5) The spinneret according to claim 3 or 4, wherein the thin layer filter is a single or porous body having pores of 5 to 200 μm. 6) The spinneret according to claim 5, wherein the shape of the hole is a perfect circle or a non-perfect circular shape such as a star shape or a polygon. 7) A plurality of thin-layer filters are stacked so that the holes of adjacent thin-layer filters partially or completely overlap, and a curved molten pitch passage is formed in the thin-layer filter layers. The spinneret according to item 5 or 6. 8) The spinneret according to claim 3 or 4, wherein the thin layer filter is formed with a slit pattern having a rectangular or predetermined shape. 9) A plurality of thin-layer filters are stacked on top of each other with slightly different relative positions so that the slit-like patterns of adjacent thin-layer filters partially overlap, and a curved molten pitch path is formed in the thin-layer filter layer. A spinneret according to claim 8. 10) The spinneret according to any one of claims 3 to 9, wherein the thin layer filter is manufactured by photolithography technology and electroforming technology.