JPH07207526A - Hollow formed material and its production - Google Patents

Abstract

PURPOSE:To obtain a polycyanoarylether hollow formed material having a good mechanical property, heat resistance, chemical resistance, bio-compatibility, and light weight property, and not having an outer diameter change and deformation, and to provide its production method with a stability and a good productivity. CONSTITUTION:A polycyanoarylether having a repeating unit expressed by the formula (Ar is a 6-20C divalent group containing an aromatic ring in its main chain) and its reduced viscosity of 0.5-3.0dl/g in a solution of 0.2 g/dl in para-chlorophenol as a solvent at 60 'C, is formed by an extrusion to a hollow formed material through a ring shaped nozzle, while blowing a nitrogen gas in an inner tube of the ring shaped nozzle at a pressure of 3-50mm H2O, at a temperature range of its melting point (Tm)-Tm+50 deg.C, and is drawn in order to make its diameter (an outer diameter) smaller than an inner diameter of an outer tube of the ring shaped nozzle at a drawing ratio of 2-1000. Further, it is adjusted that a ratio of a viscosity (poise) at a formation of polycyanoarylether and the outer diameter (mum) of the hollow formed material after the formation is 4-40, the outer diameter of the formed material is 500-4000mum, and a ratio of the inner and outer diameter is 0.7-0.98.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow molded article and a method for producing the same, and more specifically, it is excellent in mechanical properties, heat resistance, chemical resistance, biocompatibility and light weight, and has improved dimensional accuracy. TECHNICAL FIELD The present invention relates to a hollow molded article made of cyanoaryl ether and a method for stably producing the molded article, which does not cause fluctuations in outer diameter or deformation.

[0002]

2. Description of the Related Art In recent years, hollow moldings such as hollow fibers and tubes have been widely used in many fields. For example, hollow fibers are used for clothing and separation membranes, as well as in the medical field and chemical industry, and tubes are used as separation media, heat transfer tubes,
It is used as a transfer pipe in the chemical industry field, medical field, electrical field, mechanical field, and the like. Recently, high performance of products has been required in all fields,
What is excellent in strength, heat resistance, and chemical resistance is desired. As such a hollow molded article, a method for producing a fluororesin tube has been disclosed (Japanese Patent Laid-Open No. 53-13281).
3 gazette). This technique is characterized in that in order to manufacture a uniform tube, a metal wire is coated with fluororesin and then the metal wire is pulled out, and the operation is extremely complicated and costly. . Further, the fluororesin has problems in moldability and mechanical strength. Under these circumstances, hollow moldings of Super Engineering Plastics are expected, but tube-shaped moldings of Super Engineering Plastics are rarely manufactured because it is difficult to handle at high temperature during molding. . Therefore, no research has been conducted on the instability (draw resonance) of the molding of the super engineering plastics tube. Further, hollow fibers for clothing have been disclosed (Japanese Patent Laid-Open No. 49-8162).
No. 0) has a low hollow ratio, and fibers and tubes for separation membranes (Japanese Patent Publication No. 4-19890) have been proposed, but this has poor productivity in wet spinning. In addition, the heat resistance, chemical resistance, and strength are not sufficient in all cases, and in reality, the required characteristics are not satisfied.

The group of the present inventors previously applied for a hollow molded body and a method for producing the same (Japanese Patent Application No. 5-30).
3664). However, in this case, instability (draw resonance) at the time of molding is not mentioned. That is, there is no description about the relationship between the molded product size and the molding viscosity, which has a great influence on the moldability, and the pressure condition of the blowing gas. When actually molding, it is difficult to obtain a good molded product unless these factors are specified. By the way, as described in "Latest Technology of Plastic Extrusion Molding" (1993, Keiji Sawada, published by Rubber Digest), when a tube is extruded, the sizing device is generally used to define the inner diameter and the outer diameter. Is used. However, this method can be applied only to a comparatively thick tube, and since it is extruded at a low speed of several tens of meters / minute or less, it is several meters like the present invention.
It is unsuitable for forming a tube having a diameter of about m and extruding at a relatively high speed.

[0004]

Under the above circumstances, the present invention is excellent in mechanical properties, heat resistance, chemical resistance, biocompatibility and light weight, and has a hollow shape with improved dimensional accuracy. The object of the present invention is to provide a molded product and a method for producing the molded product with good productivity, in particular, without causing fluctuations in outer diameter and deformation, and stably.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a hollow molded article made of polycyanoaryl ether having a specific reduced viscosity has mechanical properties, It has excellent heat resistance, chemical resistance, biocompatibility, and light weight, and also has good dimensional accuracy. It uses an annular nozzle and uses the above polycyanoaryl ether as a gas in the annular nozzle at a specific temperature. It was found that the product can be obtained with good productivity by extrusion-molding at a specific stretch ratio while blowing. In particular, the outer diameter is in a predetermined range, and the hollow molded body made of polycyanoaryl ether having a ratio of the outer diameter to the inner diameter in a predetermined range,
It has been found that by setting the ratio of the viscosity and the outer diameter of the hollow molded body and the gas blowing pressure at the time of molding within the respective specific ranges, it is possible to obtain a stable shape without causing fluctuations in outer diameter or deformation. The present invention has been completed based on such findings.

That is, according to the present invention, (1) the reduced viscosity (η _sp / c) at 60 ° C. of a solution containing p-chlorophenol at a concentration of 0.2 g / deciliter is 0.5 to 3.0 deciliter / a hollow molded article composed of polycyanoaryl ether of g, and (2) as a particularly preferred embodiment
The hollow molded body according to the above (1), wherein the hollow molded body has an outer diameter of 500 to 4000 μm and an inner diameter to outer diameter ratio of 0.7 to 0.98. In addition, a polycyanoaryl ether having a reduced viscosity (η _sp / c) of a solution of 0.2 g / deciliter in a solvent of p-chlorophenol at 60 ° C. of 0.5 to 3.0 deciliter / g,
The above-mentioned (1), which is characterized in that the polycyanoaryl ether is extruded at a stretching ratio of 2 to 1000 while blowing a gas into the annular nozzle at a temperature in the range of melting point (Tm) to Tm + 50 ° C. of the polycyanoaryl ether using the annular nozzle In the method for producing a hollow molded article, and in the above production method, the ratio of the viscosity (poise) during molding of the polycyanoaryl ether to the outer diameter (μm) of the hollow molded article after molding is 4 to 40, Further, the present invention also provides the method for producing a hollow molded article according to (2) above, wherein the gas blowing pressure is 3 to 50 mmH ₂ O.

The hollow molded article of the present invention has a reduced viscosity (η _sp
/ C) is 0.5 to 3.0 deciliters / g, preferably 0.6
.About.2.0 deciliter / g of polycyanoaryl ether. This reduced viscosity (η _sp / c)
Is the value at 60 ° C. of a solution having a concentration of 0.2 g / deciliter using p-chlorophenol as a solvent. When the reduced viscosity (η _sp / c) is less than 0.5 deciliter / g, the average molecular weight is small and excellent mechanical strength and heat resistance cannot be obtained.
On the other hand, if it exceeds 3.0 deciliter / g, the melt viscosity becomes high and the molding process becomes difficult. The polycyanoaryl ether used here is not limited to one kind as long as it satisfies the condition of the reduced viscosity (η _sp / c), and two or more kinds of polycyanoaryl ether can be used in combination. Suitable examples of the polycyano aryl ether include those represented by the general formula (I)

[0008]

[Chemical 3]

(In the formula, Ar represents a divalent group having 6 to 20 carbon atoms and an aromatic ring in the main chain.

[0010]

[Chemical 4]

Is shown. The compound which has the repeating unit represented by these can be mentioned.

Among the polycyanoaryl ethers having the repeating unit of the general formula (I), Ar is represented by the formula

[0013]

[Chemical 5]

Those represented by the formula

[0015]

[Chemical 6]

In the general formula (II)

[0017]

[Chemical 7]

Those containing 80 mol% or more of the repeating unit represented by

In the polycyanoaryl ether having such characteristics, the repeating unit represented by the general formula (I) is
It is composed of a chaotic or ordered linear chain, and its ends are hydrogen, halogen or

[0020]

[Chemical 8]

(Wherein, X represents a halogen atom) and is blocked by a terminal group.

Of the above polycyanoaryl ethers, for example, polycyanoaryl ethers (polyether nitrile) having the repeating unit of the general formula (II) can be produced as follows. That is, the general formula (III)

[0023]

[Chemical 9]

A dihalogenobenzonitrile represented by the formula (wherein X represents a halogen atom) and the general formula (IV)

[0025]

[Chemical 10]

(In the formula, M represents an alkali metal atom.)
And an alkali metal salt of resorcin represented by the formula (1) and, if necessary, an alkali metal salt of a divalent phenol having Ar in the general formula (I) as an aromatic skeleton in a neutral polar solvent. Those are preferable. Here, as the dihalogenobenzonitrile represented by the general formula (III), for example, 2,4-dichlorobenzonitrile; 2,4
-Difluorobenzonitrile; 2,6-dichlorobenzonitrile; 2,6-difluorobenzonitrile and the like are preferably used. In the reaction, one kind or a combination of two or more kinds of these compounds may be used. Further, as the alkali metal salt of resorcin represented by the general formula (IV) and the alkali metal salt of the above divalent phenol, sodium salt or potassium salt is preferably used. The polycyanoaryl ether thus obtained has the repeating unit represented by the general formula (II) and satisfies the above-mentioned conditions of reduced viscosity (η _sp / c).

The hollow molded body of the present invention may be a hollow fiber molded body or an annular molded body (tube-shaped molded body), but a tubular molded body is preferable. Those having a diameter in the range of 500 to 4000 μm are preferable. Here, if the outer diameter is less than 500 μm, molding may be difficult, and if it exceeds 4000 μm, the efficiency of extrusion molding tends to deteriorate. Further, in the present invention, the purpose is to manufacture a relatively thin tube having a film thickness of about 10 to 500 μm, but this film thickness varies depending on the diameter, and a tube having a smaller diameter generally produces a thinner tube. The ratio of the tube inner diameter to the outer diameter is not particularly limited, but is preferably in the range of 0.7 to 0.98. This ratio is 0.
If it is less than 7, it is unfavorable in terms of efficiency, and if it exceeds 0.98, the strength is lowered, which is not preferable. From the viewpoint of efficiency and strength, the preferable ratio of the inner diameter to the outer diameter of the tube is in the range of 0.8 to 0.97. The hollow molded article of the present invention can be produced by various methods, but can be produced with good productivity by adopting the method of the present invention using an annular nozzle. This annular nozzle has a polymer (polycyanoaryl ether) flow path and a gas (gas) flow path, and the gas flow path is provided in the center of the cross section of the polymer flow path. According to the method of the present invention, the melting point of the polycyanoaryl ether used is 50 ° C. or higher than the melting point.
In a high temperature range, a desired hollow molded body can be obtained by extrusion molding at a draw ratio of 2 to 1000 while blowing gas in the annular nozzle, that is, in the gas flow path. Here, if the molding temperature is lower than the melting point, molding is impossible, and if it exceeds 50 ° C. higher than the melting point, the polycyanoaryl ether is thermally decomposed or gelled, and stable molding cannot be performed for a long time.

In order to adjust the nozzle temperature within the above temperature range and perform molding, a heating device may be attached to the nozzle and molding may be performed while controlling the temperature. Of course, a molded product can be obtained without attaching a heating device to the nozzle, but in this case, the temperature other than the nozzle needs to be high, which may cause thermal deterioration of the polymer. Therefore, it may not be possible to perform stable molding for a long time. Further, the precise temperature control of the nozzle cannot be performed, which causes nonuniformity of the diameter of the obtained molded body. The gas blown into the nozzle is not particularly limited, and an inert gas or air can be used, but from the viewpoint of preventing deterioration of the polycyanoaryl ether, it is preferable to use an inert gas such as nitrogen.
The temperature of the gas at that time is preferably heated so as to approach the molding temperature of the polycyanoaryl ether used.

Further, if the stretching ratio (polymer tension rate / polymer flow rate in the nozzle) is less than 2, the dimensional stability of the obtained molded article is poor, and if it exceeds 1000, the strain rate increases and fracture occurs in the molded article. Molding becomes difficult. The annular nozzle used in the method for producing the hollow molded body has an outer tube inner diameter of 0.5 to 20 mm, preferably 1 to 10 mm.
mm, and the ratio of the outer diameter of the inner pipe to the inner diameter of the outer pipe is 0.5
Those in the range of to 0.98, preferably 0.6 to 0.95 are suitable. According to the method of the present invention as described above, it is possible to produce a hollow molded body having a diameter [diameter (outer diameter)] larger than the inner diameter of the outer tube of the annular nozzle. From this point of view, it is preferable to manufacture a hollow molded body having a diameter [diameter (outer diameter)] smaller than the inner diameter of the outer tube of the annular nozzle. Among the hollow moldings of the present invention, as described above,
A tubular molded body having an outer diameter in the range of 500 to 4000 μm and a ratio of the inner diameter to the outer diameter in the range of 0.7 to 0.98 is preferable, and a tubular molded body having such a shape is
According to the method of the present invention, it can be manufactured as follows.

The viscosity at the time of molding (hereinafter simply referred to as molding viscosity) tends to be relatively high when the tube diameter after molding (hereinafter simply referred to as tube diameter) is large. Therefore, it is advantageous to use the ratio of the molding viscosity (poise) to the tube diameter (μm) as a parameter representing the molding conditions. In order to produce a tubular molded body of the above shape, the molding viscosity / tube diameter ratio is 4-40.
Is preferred. If this ratio is less than 4, it means that the viscosity is small relative to the tube diameter, and the tube breaks,
There is a risk of breakage, and when it exceeds 40, the viscosity is too high to make extrusion difficult, and there is a problem of melt fracture, and it is not possible to increase the draw ratio, and low productivity is preferable. The tube diameter ratio is in the range of 5-30.

The molding viscosity (η) (poise) is calculated from the following equation, assuming Poiseuille flow of an annular pipe.

[0032]

[Equation 1]

[Wherein ΔP: pressure difference (Pa), R: outer pipe inner diameter (m), L: pipe length (m), Q: flow rate (m ³ / s)
ec), outer diameter ratio of inner tube to κ: R].

The stretching ratio (polymer tension rate / polymer flow rate in the nozzle) can be arbitrarily selected, but is preferably 2 to 400. If the stretching ratio is too small, it means that the productivity is low. In addition, as the effect of stretching, the product discharged from the nozzle is also stretched to flatten the surface irregularities. Therefore, the larger the draw ratio is, the more preferable it is. However, if the draw ratio is too large, the strain rate also increases, which causes draw resonance or breaks of the molded product. When the outer diameter is less than 500 μm, the stretching ratio is 2
It is preferable that the outer diameter is 500 to 40
At 00 μm, a draw ratio of 2 to 400 is advantageous.

Further, the gas blowing pressure into the tube needs to be a positive pressure, and the gas blowing pressure is 3 to.
It is 50 mmH ₂ O. If this pressure is too low, the product tube may be crushed or deformed during molding. On the contrary, if the pressure is high, the tube diameter can be controlled to be large even if the nozzle diameter is small, but a slight disturbance may cause non-uniform deformation or draw resonance, so it is necessary to strictly control the tube diameter. This pressure is more preferably 4 to 40 mmH ₂ O. In a more preferable range, a stable product can be obtained. In this way, the tubular molded body having an outer diameter in the range of 500 to 4000 μm and a ratio of the inner diameter to the outer diameter of the tube in the range of 0.7 to 0.98 is subject to outer diameter fluctuation and deformation. It is stable and can be obtained with good productivity.

[0036]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. Example 1 (molding a tube) The polycyanoaryl ether used was of the formula

[0037]

[Chemical 11]

A polymer compound having a repeating unit represented by the formula: reduced viscosity (η _sp / c) 1.0 deciliter /
g, melting point 340 ° C. The nozzle used for extrusion molding is an annular monohole nozzle having an outer tube inner diameter of 2 mmφ and an inner tube outer diameter of 1.2 mmφ. 1 and 2 show a longitudinal sectional view and a lateral sectional view of the annular nozzle, respectively. In the figure, P is a polymer, G is an inert gas, Di is the outer diameter of the inner tube of the annular nozzle, and Do is the inner diameter of the outer tube of the annular nozzle. While blowing nitrogen gas into the inner tube of this annular mono-hole nozzle, a tube was molded from the annular portion at a flow rate of 33 cc / min and a pulling speed of 80 m / min. The resulting tube had an outer diameter of 1000 μm and an inner diameter of 6
90 μm, stretch ratio 4.9, amorphous state, thickness variation is 1
It was within 0 μm. Similarly, the above polycyanoaryl ether was fed from the cyclic portion at a flow rate of 33 cc / min and a pulling rate of 8
The tube molded at 00 m / min was in an amorphous state with an outer diameter of 250 μm × inner diameter of 100 μm and a stretching ratio of 49. As a result of tensile test of the latter tube, tensile strength was 1350 kg /
cm ² , tensile elastic modulus 3.42 × 10 ⁴ kg / cm ² , elongation 148%, no distortion into an ellipse, and thickness variation of 5μ
It was within m. The hollow rate was 48%.

Example 2 (molding of hollow fiber) The polycyanoaryl ether used had the same structure as in Example 1 and had a reduced viscosity (η _sp / c) of 0.83 deciliter / g and a melting point of 340 ° C. is there. For extrusion molding,
An extruder equipped with a die having 24 annular nozzles, each nozzle being an annular monohole nozzle having an outer tube inner diameter of 0.36 mmφ and an inner tube outer diameter of 0.14 mmφ. While blowing nitrogen gas into the inner tubes of these annular nozzles, hollow fibers were molded from the annular portion at a flow rate of 0.85 cc / min per nozzle and a pulling rate of 1200 m / min (drawing ratio 120). The obtained hollow fiber was continuously stretched at 200 ° C. to 4.20 times and further heat-treated at 240 ° C. The obtained hollow fiber was subjected to a tensile test. As a result, the thickness was 1.9 denier, the tensile strength was 7.5 g / denier, the tensile elastic modulus was 1.40 × 10 ⁵ kg / cm ² , and the elongation was 1.
The tensile strength at 150 ° C. was 5.1 g / denier. The hollow rate was 35%.

Example 3 (Molding of tube) A polycyanoaryl ether having a reduced viscosity (η _sp / c) of 1.45 deciliter / g and a structure similar to that of Example 1 was used. A tube was formed in the same manner as in Example 1 except that a nozzle having a diameter of 10.2 mmφ was used and the flow rate was 57 cc / min and the pulling speed was 25 m / min. The obtained tube has an outer diameter of 5 mm and an inner diameter of 4.7 m.
It was in an amorphous state with mφ, wall thickness of 150 μm, and stretching ratio of 14. As a result of tensile test of this tube, the tensile strength was 123.
0 kg / cm ² , tensile elastic modulus 3.10 × 10 ⁴ kg / cm
² , the elongation was 155%, there was no distortion into an ellipse, and the thickness variation was within 10 μm. In addition, the surface of the molded body was smooth and no seams were observed by microscopic observation. The hollow rate was 88%.

Comparative Example 1 (Molding of Tube) A slit speed nozzle shown in FIG.
A hollow molded body was produced in the same manner as in Example 1 except that m / min was set. In FIG. 3, A is the inner diameter of the nozzle, which is 1.5.
mm, B is the outer diameter of the nozzle is 2.0 mm, and C is the width of the slit is 0.2 mm. In the obtained hollow molded article, the thickness of the fused portion was non-uniform, and vertical streaks were observed in the longitudinal direction.
The hollow rate was 18%, which was extremely low.

Comparative Example 2 (Molding of Tube) A hollow molded body was produced in the same manner as in Example 1 except that the stretch ratio was 1.2. The obtained hollow molded article was difficult to uniformly cool the solidification zone near the nozzle, the thickness variation was 50 μm or more, and a tube having a constant diameter could not be obtained.

Example 4 and Comparative Examples 3 and 4 (tube molding) Reduced viscosity (η _sp / c) 1.0 deciliter / g, melting point 34
Tube molding was performed using a polycyanoaryl ether having the same structure as in Example 1 at 0 ° C. The nozzle attached to the die was a concentric annular nozzle, and nitrogen gas was blown from the center. The nozzle used is an outer tube inner diameter of 6 mm
φ, the outer diameter of the inner tube is 5 mmφ. An experiment was conducted under the conditions shown in Table 1, and the results shown in the table were obtained.

Example 5 and Comparative Example 5 (tube molding) Reduced viscosity (η _sp / c) 1.4 deciliter / g, melting point 34
An experiment was performed in the same manner as in Example 1 using a polycyanoaryl ether having the same structure as in Example 1 at 3 ° C. In this case, an experiment was conducted by using a nozzle having an outer tube inner diameter of 10 mmφ and an inner tube outer diameter of 7.6 mmφ and changing the temperature to a low temperature side. An experiment was conducted under the conditions shown in Table 1, and the results shown in the table were obtained.

Example 6 and Comparative Example 6 (Tube molding) Reduced viscosity (η _sp / c) 0.83 deciliter / g, melting point 3
Experiments were conducted using a relatively low molecular weight polymer of polycyanoaryl ether having the same structure as in Example 1 at 40 ° C. In this case, the outer diameter is 7.0mmφ and the inner diameter is 5.6.
A mmφ nozzle was used. An experiment was conducted under the conditions shown in Table 1, and the results shown in the table were obtained.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

Industrial Applicability The hollow molded article of the present invention has mechanical properties,
In addition to excellent heat resistance, chemical resistance, biocompatibility and light weight,
Good dimensional accuracy. Further, according to the method of the present invention, this product can be stably manufactured with high productivity and without causing fluctuations in outer diameter or deformation. The hollow molded article of the present invention is a clothing, a separation medium, a heat insulating material, a filler, an adsorbent (carrier), a liquid / gas transport pipe requiring heat resistance and chemical resistance, and a chemical resistance heat exchanger tube. It can be effectively used for a catheter tube, a separation hollow tube, and the like.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an annular nozzle used in Examples and Comparative Examples.

FIG. 2 is a cross-sectional view of annular nozzles used in Examples and Comparative Examples.

FIG. 3 is a transverse cross-sectional view of a slit-shaped nozzle used in Comparative Example 1.

[Explanation of symbols]

 P: Polymer G: Inert gas Di: Outer tube outer diameter of annular nozzle Do: Outer tube inner diameter of annular nozzle A: Nozzle inner diameter 1.5 mm φ B: Nozzle outer diameter 2.0 mm φ C: Slit width 0.2 mm 1: Polymer flow path 2: Gas flow path

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location D01F 6/00 B

Claims (8)

[Claims] 1. 0.2 as a solvent using p-chlorophenol
A hollow molded article made of polycyanoaryl ether having a reduced viscosity (η _sp / c) of a solution having a concentration of g / deciliter at 60 ° C of 0.5 to 3.0 deciliter / g. 2. A polycyanoaryl ether has the general formula (I): [In the formula, Ar represents a divalent group having 6 to 20 carbon atoms and an aromatic ring in the main chain. ] The hollow molded article according to claim 1, which has a repeating unit represented by the following formula. 3. The ratio of the inner diameter to the outer diameter of the hollow molded body is 0.7.
The hollow molded body according to claim 1, wherein the hollow molded body has a density of about 0.98. 4. The hollow molded body has an outer diameter of 500 to 4000.
The hollow molded body according to claim 1, wherein the hollow molded body has a diameter of 0.1 μm and a ratio of inner diameter to outer diameter of 0.7 to 0.98. 5. 0.2 as a solvent using p-chlorophenol
A polycyanoaryl ether having a reduced viscosity (η _sp / c) of 0.5 to 3.0 deciliters / g at 60 ° C. in a solution having a concentration of g / decyl is 0.5 to 3.0, and a melting point of the polycyanoaryl ether ( Tm) to Tm + 50 ° C
A method for producing a hollow molded article, which comprises extruding at a draw ratio of 2 to 1000 while blowing gas into the annular nozzle at a temperature in the range. 6. The polycyanoaryl ether has the general formula (I): [In formula, Ar is the same as the above. ] The manufacturing method of Claim 5 which has a repeating unit represented by these. 7. The diameter (outer diameter) of the hollow molded body to be manufactured
Is smaller than the inner diameter of the outer tube of the annular nozzle.
The manufacturing method described. 8. The ratio of the viscosity (poise) during molding of the polycyanoaryl ether to the outer diameter (μm) of the hollow molded body after molding is set to 4 to 40, and the gas blowing pressure is set to ₃ to 50 mmH _2. Outer diameter 500 to 4000 under the condition of O
The manufacturing method according to claim 5, wherein a hollow molded body having a diameter of μm and an inner diameter / outer diameter ratio of 0.7 to 0.98 is manufactured.