JPH05222230A - Method of coating tube inside surface - Google Patents

Abstract

PURPOSE:To coat a tube with an organic thin film on its inside surface by setting a tube in which a gas is flowing in a cylindrical reactor, controlling the gas pressures inside and outside the tube and converting an organic compound and a non-polymerizable gas into plasma. CONSTITUTION:A tube 2 is set through the joint 3 to the inside of the cylindrical reactor 1. In the tube 2, pressure difference is made between the both ends of the tube so that the gas flows through the inside. When the organic compound is gaseous, a mixture of the gas and a non-polymerizable gas is introduced into the inside of the tube 2, while the non-polymerizable gas is into the outside of the tube 2. At this time, an electric current is fed from the high-frequency power source 9 through the matching unit 8 to the coil 7, as the pressure on the higher pressure side PH in Torr and the lower side pressure PL in Torr, the pressure outside the tube, and Pout satisfy the conditions represented by the equations I, II and III (R is inner diameter of the reactor; r is inner diameter of the tube; S is total cross section of the tube in mm<2>) through the inlet and outlet of the gas 4, the vacuum evacuator 5 and the gas introducer 6. Thus, the organic compound and the non-polymerizable gas are converted into plasma to coat the inside surface of the tube 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention controls the gas pressure inside and outside the tube in consideration of the inner diameter of the tube and the inner diameter of the reaction tube so that the inner surface of the tube in which a gas having an inner diameter of 0.01 mm to 3 mm is flowing is an organic thin film. The present invention provides a new function to the inner surface of the tube.

[0002]

2. Description of the Related Art An organic thin film coating technique for plasma-polymerizing an organic compound on a flat surface is widely known as a means for imparting a new function to the surface by utilizing plasma together with surface modification of non-polymerizable gas by plasma. There is. In addition, the functions imparted by plasma polymerization are diverse in terms of weather resistance, corrosion resistance, wettability, adhesiveness, substance separability, and many proposals have been made in the past.
The surface coating by plasma polymerization has a basic technique in which an organic compound activated in a relatively wide gas phase space is deposited and polymerized on the surface of a substrate placed in a region where plasma is generated. Therefore, it is not easy to uniformly coat the inner surface of a thin tube having a small gas phase space by this method. For example, if the inner diameter is several mm and the inner diameter is 100
For the purpose of coating the inner surface of a tube with a length more than twice the length with a plasma polymerized film, even if an attempt was made to introduce the plasma generated outside the opening end into the tube using the pressure difference, Since it is deactivated, the polymerized film is formed only near the open end of the tube. When the tube is a hollow fiber separation membrane, the inner diameter is usually 3 mm or less for an ultrafiltration membrane, 0.5 mm to 0.1 mm for a gas separation membrane, and 0.1 mm or less for a dialysis membrane. Special coating is required to coat the inner surface of such a tube having a small inner diameter with a plasma polymerized film, and some methods have been proposed.

Yasuda et al. J. Appl. Polym. Sci, 38, 65 (198
4) shows the method of coating the inner surface of a plastic tube with an inner diameter of 3 mm. The apparatus proposed by this method consisted of two chambers connected by a tube with an inner diameter of 1/2 inch, to which an electrode was attached, and a reaction tube which was kept at 10 ^-3 Torr, and was installed inside it. It consists of a tube winding part. A shaft for winding the tube is installed in each room, and the tube in which the organic gas has flowed is wound from the pre-wound shaft to the other shaft, and the inner diameter where the electrode is attached in the middle Pass through a 1/2 inch tube. A high frequency power source is connected to this electrode, and when the tube passes through this reaction tube portion, plasma is generated only inside the tube to coat the inner surface of the tube. Yasuda et al. Believe that this method enables the practical application of an organic membrane coating on the inner surface of a thin tube, and expects application of the hollow fiber membrane for gas separation as an example to the inner surface coating.

However, such a tube inner surface coating method is limited to flexible polymer tubes, cannot be applied to hard tubes such as ceramics, and can be solved even when the tubes are hollow fiber gas separation membranes having excellent flexibility. There are many challenges to be done. That is, the device becomes complicated and large, such as installing a winder in the reaction tube,
Since the tube to be coated is wound up, tension may be applied to the tube and the tube may be damaged, and it is extremely difficult to introduce the organic gas into the wound thin hollow fiber. Furthermore, the hollow fiber gas separation membrane is put to practical use as a module in which a large number of tens of thousands of tubes are bundled in the case of a large number, and when converted to a length, it becomes enormous. Even if they are collectively sent to the reaction tube, it takes a long time to process the necessary amount. It is also necessary to consider that the plasma polymerized film formation is not a fast reaction process. From the above problems, it is economically desirable for the inner surface treatment of the gas separation membrane to be able to perform the batch treatment after the module is prepared, but the above method cannot perform the batch treatment.

Further, Japanese Patent Application Laid-Open No. 54-56672 discloses a coating method for the inner surface of a polymer tube having an inner diameter of 3-4 mm. To this end, a tube made of a polymer to be treated is installed in the insulating tube, the inside of the insulating tube is kept at a pressure of 1 Torr or more, the inside of the tube is kept at a lower pressure than the inside of the insulating tube, and By applying a voltage, plasma is generated on the inner surface of the tube,
A method of coating the inner surface of the tube with a plasma polymerized film has been proposed.

However, as a preferable pressure range for coating, the inside of the tube to be coated has a pressure of 0.
01 to 10 Torr and 10 to 100 Torr outside, it is necessary to consider the relationship between the mean free path of electrons and plasma generation as described below for plasma generation in a tube having an inner diameter of 3 mm or less, particularly 1 mm or less. is there.

In order to process the inner surface of the tube with plasma, it is a necessary condition to internally generate plasma. For plasma generation, collisions of electrons and molecules must occur frequently enough to sustain the plasma. The mean free path of electrons is about 1/10 mm in 1 Torr of argon, although it depends on the energy of the electrons. Therefore, the frequency of collision with the wall surface of the tube having an inner diameter of 3 mm or more is rare with respect to the frequency of collision with argon atoms, and can be ignored for plasma generation. However, if the inner diameter of the tube is 3 mm or less, especially 1 mm or less, the same 1To
Under the condition of rr, the mean free path of electrons is about the same as the inner diameter of the tube, so the frequency of collision of electrons with the inner wall surface of the tube cannot be ignored, and as a result, plasma is less likely to be generated. Here, since the mean free path of electrons is inversely proportional to the gas pressure, the pressure at which plasma can be generated inside the tube has a lower limit depending on the tube inner diameter. In particular, when the inner diameter is 1 mm or less, there is a lower pressure limit for plasma generation in the vicinity of the pressure range in which coating is usually performed, so it is important to know the relationship dependence of the plasma generation pressure range when performing tube inner surface coating. That is, since the appropriate pressure for coating the inner surface of a tube having an inner diameter of 1 mm or less greatly differs depending on the inner diameter, it is not sufficient to specify the above range of 0.01 to 10 Torr irrelevant to the inner diameter of the tube.

Further, a method of generating plasma only inside the tube by setting the pressure inside the insulating tube higher than the pressure inside the tube is shown, but the relationship between the mean free path of electrons and the plasma generation is described above. From the consideration, it is understood that plasma can be generated only inside the tube by lowering the pressure outside the tube below the pressure inside the tube. Considering the inner surface coating of the hollow fiber separation membrane, it is understood that the pressure outside the hollow fiber is lower than that inside because the membrane has gas permeability. When the pressure on the outside of the hollow fiber is higher than the inside, there is a flow of gas from the outside to the inside through the membrane,
Mixing of different gases may change the internal plasma generation conditions for hollow fiber inner surface coating. When the external pressure is set low, there is no mixing of new gas inside, so coating with good reproducibility can be achieved.

Further, a tube having an inner diameter of usually 1 mm or less, such as a hollow fiber separation membrane, is difficult for gas to flow and has a large pressure loss. However, the larger the pressure loss, the longer it takes to set a constant pressure inside the tube. .. Therefore, even if the gas is introduced into a tube having gas permeability such as a hollow fiber separation membrane and the inside is kept at a constant pressure, the pressure must be increased by the gas permeation through the tube surface until the pressure becomes constant. It will change. Therefore, in order to perform a uniform coating with good reproducibility on the inner surface of a tube such as a hollow fiber separation membrane that has a small inner diameter of the tube and a large pressure loss and has gas permeability, the gas must be flown inside and outside the tube. In this state, it is advantageous to set the external pressure lower than the internal pressure.

[0010]

In order to coat the inner surface of a tube having an inner diameter of 0.01 to 3 mm with plasma, plasma must first be generated inside the tube. For that purpose, the following two conditions must be satisfied at the same time. These conditions are that the mean free path of electrons inside is short enough that collision with the inner wall of the tube is negligible compared with collision with gas molecules, and plasma is not generated inside the tube.

In view of the problems in the prior art as described above, the present invention provides a tube inner diameter and a tube inner portion in a vacuum system capable of independently controlling the pressure inside and outside the tube having an inner diameter of 0.01 to 3 mm. Inside diameter of the reaction tube installed in
By providing a pressure inside the tube, a pressure outside the tube, and the like within a certain range, plasma is generated only inside the tube in which gas is flowing, and the inside surface of the tube is suitably coated with a plasma polymerized film. .. Further, the present invention provides a method for suitably coating the inner surfaces of the bundled and modularized tubes all together with a plasma-polymerized film.

[0012]

According to the present invention, a pressure difference is provided at both ends in consideration of the inner diameter of the tube and the inner diameter of the reaction tube, and the gas pressure inside and outside the tube through which the gas flows is controlled. To solve the problem of.

That is, according to the present invention, a tube having an inner diameter of 0.01 mm to 3 mm or a bundle of the tubes 2 which is installed in a cylindrical reaction tube 1 is installed, and a pressure difference is provided at both ends of the tube. Gas is flowed, and at this time, the reaction tube inner diameter R
(Mm), tube inner diameter r (mm), high pressure side pressure P ^H in (Torr), low pressure side pressure P ^L in (Torr), tube outside pressure P out (Torr), total sum S of tube cross sections (Mm ² ), 4.5 × 10 ⁻² / r <P ^L in <P ^H in <P out or 4.5 × 10 ⁻² / r <P ^L in <P ^H in and Pout <4. Under the condition that any of 5 × 10 ^-2 / (R-2π ^-1/2 S ^1/2 ) is satisfied, the tube is formed by plasmatizing the organic compound and the non-polymerizable gas in the inner space of the tube 2. In this method, the inner surface is coated with an organic plasma polymer. Here, the sum S of the cross-sectional areas of the tubes indicates the cross-sectional area of the module constituted by the bundled tubes, and when the tube is composed of one tube,
Naturally, it is the cross-sectional area of the tube.

In the present invention, when the organic compound polymerized by plasma is a gas, the mixed gas of the organic gas and the non-polymerizable gas is converted into plasma inside the tube to coat the inner surface of the tube. be able to.

When the organic compound polymerized by plasma is non-volatile, the organic compound is applied to the inner surface of the tube in advance, and then the non-polymerizable gas is turned into plasma inside the tube to form a plasma polymerized film on the inner surface of the tube. Can be coated with. In addition, an organic compound that is polymerized after previously treating the inner surface of the tube with plasma of a non-polymerizing gas may be introduced into the tube. Further, the present invention is a hollow fiber membrane in which a tube coated with a plasma polymer has a function of separating molecules by adsorption and diffusion,
Further, the one in which the tubes are bundled and coated on the inner surface at one time is suitable for the case where the hollow fiber membrane is a hollow fiber separation membrane module in which both bundled ends of the hollow fiber membrane are fixed with a resinous substance and hollow holes are opened at both ends. is there.

[0016]

Action The mean free path of electrons in a gas is inversely proportional to the gas pressure. Therefore, the higher the gas pressure is, the shorter the mean free path of electrons is. Therefore, the lower limit of the gas pressure inside the tube required to generate plasma in the tube, which is shown in the above problem, is defined by the tube inner diameter r (mm). Can be decided in consideration. That is, the inner diameter is 0.01 mm to 3 mm,
Preferably At a tube 0.01 mm to 2 mm, determine the relation between the P ^L in the r from the mean free path << Bore conditions of the electron, by obtaining from the coefficient experiment, plasma within the tube Internal high-pressure side pressure P ^H in (Torr) and low-pressure side pressure P ^L
The condition of in (Torr) is 4.5 × 10 ⁻² / r <P ^L in <P ^H in
Is.

On the other hand, there are two methods for satisfying the condition that plasma is not generated outside the tube.
The first method is gas pressure Pout (Torr) outside the tube.
Is higher than the inside. That is, P ^H in <P out. This method is based on the principle of plasma generation, in which the higher the pressure, the shorter the mean free path of electrons, and the less energy is acquired during that time, which requires a large output to generate plasma. Therefore, if the pressure outside the tube becomes high, it becomes difficult for plasma to be generated outside the tube, and if the output is the same, plasma is generated inside the tube where the gas pressure is low. The second method that does not generate plasma outside the tube is to reduce the inner diameter R (mm) of the cylindrical reaction tube 1 in which the tube is installed, or to reduce the gas pressure outside the tube, or both. This is a method in which the average free path of electrons outside the tube is made longer than the characteristic length of the space outside the tube so that the frequency of collisions between electrons and gas molecules is less than or equal to that required to maintain plasma.
That is, the mean free path of the electron >> The characteristic length of the tube outer space, Pout and the characteristic length of the tube outer space, R
-2π ^-1/2 S ^1/2 , and the coefficient is obtained from an experiment, so that Pout <4.5 × 10 ^-2 / (R-2π
^-1/2 S ^1/2 ) should be satisfied.

From the above-mentioned examination result of the plasma generation condition,
The condition for generating plasma only inside the tube in which the gas is flowing is 4.5 × 10 ^-2 / using a vacuum system that can control the pressure inside and outside the tube with an inner diameter of 0.01 to 3 mm independently. r <P ^L in <P ^H in <P out or 4.5 × 10 ⁻² / r <P ^L in <P ^H in and Pout <4.5 × 10 ⁻² / (R−2π ^−1/2 S ^{1 / 2} ) is satisfied.

[0019]

EXAMPLE FIG. 1 shows an inductively coupled plasma polymerization apparatus for carrying out the present invention. An organic gas and a rare gas are introduced into the tube module 2 from the gas introduction device 6, and while the gas is exhausted by the vacuum evacuation device 5, the gas supply amount and the valve on the exhaust side are used to adjust the tube internal pressure to achieve a steady state. Set to the set pressure value with. The external pressure is set through the gas introduction / exhaust unit 4. still,
Actually, the gas introduction / exhaust unit 4 may be one or plural. Module 2 consists of 1 tube
A book or a bundle of a plurality of pieces is fixed with a resin. The module 2 and the joint portion 3 of the reaction tube 1 may be any as long as they maintain hermeticity, and an adhesive, a vacuum packing or the like can be used. Further, the end face of the module may be formed in a flange shape so that it can be easily handled. Furthermore, the plasma generation method is an inductive coupling method, and a current is supplied to the coil 7 from the high frequency power supply 9 through the matching device 8. Here, as a plasma generation method, there are an inductive coupling method in which a high frequency voltage is applied to a coil and a capacitive coupling method in which a high frequency voltage is applied between opposed parallel plates. In the present invention, a tube to be coated is used. It suffices that an electric field is generated in the direction perpendicular to the length direction of the plasma, and any method of generating plasma may be used. The frequency of the power supply for generating plasma is 10kHz or less, and 13.56MHz, 27.12MH
z, 40.68MHz, 2.48GHz, 5.8GHz, 22.1
Any of 25 GHz can be used.

As the non-polymerizable gas flowing inside the tube for generating plasma, a single gas or a mixed gas such as nitrogen can be used in addition to a rare gas such as helium and argon, but helium is easy to generate plasma. Is excellent. In the present invention, since the condition that plasma is not generated outside the tube is satisfied regardless of the type of gas, there is no limitation on the gas introduced into the outside of the tube.

If a polymerizable organic compound is present inside the tube in which plasma is generated, the inner wall of the tube can be covered with a plasma polymerized film, and a new function is added. When the polymerizable organic compound is a gas, a mixed gas of the gaseous organic compound and a non-polymerizable gas that is easily turned into plasma may be flowed inside the tube. When the organic compound is easily turned into plasma, the organic compound gas alone may be used. When plasma-polymerizing a non-volatile organic compound, for example, the organic compound is dissolved in a volatile solvent, the inner wall of the tube is previously coated with a target polymerizable compound by a means such as spreading, and then the non-volatile compound is introduced. A polymerized film may be formed by exciting with plasma of a polymerizing gas. It is also possible to activate the inner wall of the tube with plasma of a non-polymerizable gas alone and then to flow a polymerizable organic gas to form a thin polymer film. Which of these methods is used to coat the inner surface of the tube with the plasma polymerized film is selected depending on the polymerizable organic substance used and the function of the intended polymerized film.

In the tube inner surface coating method of the present invention, if the inner and outer gas pressure conditions of the tube are satisfied, the inner surface of the tube having an inner diameter of 0.01 mm to 3 mm is coated with a plasma-polymerized film regardless of the number of tubes. Can be coated. That is, even in the case of a large number of tube aggregates such as the hollow fiber gas separation membrane module, the inner surface thereof can be coated with the plasma polymerization membrane at once. As a result, it becomes possible to collectively repair defects that have occurred in the spinning process of the hollow fiber membrane or defects that have occurred in the steps from spinning to assembly of the separation membrane module. Also,
As a matter of course, a new function can be added to the hollow fiber separation membrane. As an example, an inner pressure type hollow fiber gas separation membrane can be obtained by plasma-polymerizing an organic silicon compound on the inner wall of the porous hollow fiber membrane. In addition, a hollow fiber gas separation membrane using a polyamide as a raw material obtained by polycondensation of a 4,4-bis (4-aminophenyl) fluorene derivative and phthalic acid chloride, which has been already proposed by the applicants of the present application (for example, Japanese Patent Laid-Open No. Hei 2 −
After making the hollow fiber into a module, the inner surface of the hollow fiber can be coated with a plasma-polymerized membrane by the coating method of the present invention to make the separation membrane highly functional.

The present invention will be described below with reference to specific examples and comparative examples.

Example 1 A plasma polymerization apparatus having the structure shown in FIG.
10 Pyrex tubes with an outer diameter of 1.5 mm and a length of 550 mm bundled with epoxy resin 2 and an inner diameter of 10
It was fixed at the center of a 0 mm cylindrical reaction tube 1 so that the pressure inside and outside the Pyrex tube could be controlled independently. After the inside and outside of the tube were both evacuated to 10 ^-3 Torr, helium gas was introduced into the outside of the tube to keep the external pressure (Pout) at 400 Torr, and the inside of the tube was filled with helium and hexafluorobenzene (C ₆ F). ₆ ) mixed gas (molar ratio, He / C ₆ F ₆ = 10) is introduced, the high pressure side pressure (P ^H in) is 50 Torr, and the low pressure side pressure (P ^L in) is 1
Kept on Torr. In this example, the pressure range of the present invention is 0.
09Torr <P ^L in <P ^H in <P out, or 0.09 Tor
r <a P ^L in <P ^H in and Pout <4.7 × 10 ^-4 Torr, the pressure in this example is in the range of the first condition. Frequency of 13.56 MH in coil 7 wound around the reaction tube
When a current of z was applied, plasma was generated only inside the tube. When the plasma treatment was performed for 1 minute, a uniform film having a thickness of about 30 nm was formed on the inner surface of the tube.

Example 2 A plasma polymerization apparatus having the structure shown in FIG.
10 Pyrex tubes with an outer diameter of 1.5 mm and a length of 550 mm bundled with epoxy resin 2 and an inner diameter of 10
It was fixed at the center of a 0 mm cylindrical reaction tube 1 so that the pressure inside and outside the Pyrex tube could be controlled independently. Keep the tube external pressure (Pout) at 10 ^-6 Torr,
After the inside of the tube was evacuated to 10 ^-3 Torr, the outside of the tube was kept at this pressure, and the inside of the tube was mixed with helium and hexafluorobenzene (C ₆ F ₆ ) gas (molar ratio, He / C ₆ F). ₆ = 10) and the pressure on the high pressure side (P ^H i
n) was maintained at 50 Torr and the low-pressure side pressure (P ^L in) was maintained at 1 Torr. In the case of this example, the pressure range of the present invention is the same as that of the first embodiment, but the pressure is set within the range of the condition where the external pressure is lower than the second internal pressure. When a current having a frequency of 13.56 MHz was applied to the coil 7 wound around the reaction tube, plasma was generated only inside the tube. When the plasma treatment was performed for 1 minute, a uniform film having a thickness of about 30 nm was formed on the inner surface of the tube.

Example 3 A plasma polymerization apparatus having the structure shown in FIG.
A module 2 in which 100 silicon tubes having an outer diameter of 0.5 mm were bundled was prepared and fixed in the center of a reaction tube 1 having an inner diameter of 100 mm using a resin as in Example 1. After the inside and outside of the polymer tube were both evacuated to 10 ^-3 Torr, helium gas was introduced into the outside of the polymer tube to keep the external pressure (Pout) at 300 Torr, and the inside of the tube was filled with helium and hexafluoro. By introducing a mixed gas of benzene (C ₆ F ₆ ) (molar ratio, He / C ₆ F ₆ = 10), the high pressure side pressure (P ^H in) is 50 Torr and the low pressure side pressure (P ^L in) is 1 To.
After maintaining at rr, a current having a frequency of 13.56 MHz was immediately passed through the coil 7 wound around the reaction tube to generate plasma only inside the tube. In this example, the pressure range of the present invention ^{0.15Torr <P L in <P H} in <Pout or 0,.
15 Torr <P ^L in <P ^H in and Pout <4.7 × 10 ⁻⁴ T
orr, and the pressure in this example is set within the range of the first condition. When the plasma treatment was performed for 1 minute, a uniform film having a thickness of about 30 nm was formed on the inner surface of the polymer tube.

COMPARATIVE EXAMPLE A polyamide obtained by polycondensation of 9,9-bis (4-aminophenyl) fluorene of approximately equimolar amount and terephthalic acid chloride in an N, N-dimethylacetamide solution as a raw material has an inner diameter of 0.2 mm. A gas separation hollow fiber membrane having an outer diameter of 0.4 mm was obtained. 200 hollow fiber membranes were bundled and an open end was embedded with an epoxy resin to prepare a gas separation membrane module with an effective length of 90 cm. The permeation rates of oxygen and nitrogen of the obtained gas separation membrane module in a dry state at 25 ° C. and a relative humidity of 40% are shown in the comparative example column of Table 1.

Example 4 In each hollow fiber of the gas separation membrane module 2 similar to the comparative example, 1% acetone of amide oligomer obtained from 9,9-bis (4-aminophenyl) fluorene and a large excess of terephthalic acid chloride. After injecting the solution, the solvent was evaporated at room temperature to attach the amide oligomer to the inner wall of the hollow fiber. The gas separation unit was fixed in the cylindrical reaction tube 1 in the same manner as in Example 3, the outside of the hollow fiber was evacuated, and the external pressure (Pout) was set to 1.
Helium gas was introduced into the hollow fiber at 0 ^-5 Torr and the internal high pressure side pressure (P ^H in) was maintained at 50 Torr and the low pressure side pressure (P ^L in) was maintained at 1 Torr to generate plasma for 1 minute, The amide oligomer was immobilized on the inner wall of the hollow fiber by plasma to make it insoluble. In this case, the pressure range of the present invention is
^{0.23Torr <P L in <P H} in <Pout or 0.2,
3 Torr <P ^L in <P ^H in and Pout <4.8 × 10 ⁻⁴ Tor
r, and the pressure in this example is set within the range of the second condition. The gas permeation performance of the obtained hollow fiber gas separation membrane module 2 is shown in Example 1 of Table 1. This plasma treatment has the effect of improving the oxygen-nitrogen separation rate.

Example 5 Subsequent to the plasma treatment of Example 4, the inside of each hollow fiber of module 2 was replaced with 50 Torr of tetrafluoroethylene,
The reaction was made with the inner wall of the activated hollow fiber for 5 minutes. Furthermore, under the same pressure conditions as in Example 4, that is, the hollow fiber external pressure (Pout)
10 ^-5 Torr, high pressure inside the hollow fiber (P ^H in) 50 Tor
r, repeated low side pressure (P ^L in) 3 times the operation of introducing tetrafluoroethylene hollow fiber interior after the plasma treatment at 1Torr helium environment. The performance of the gas separation membrane module 2 obtained by such treatment is shown in the column of Example 5 in Table 1. This plasma treatment suppresses a decrease in the oxygen-nitrogen separation rate in humidity.

[0030]

[Table 1]

[0031]

By controlling the pressure inside and outside the tube having an inner diameter of 0.1 to 3 mm, plasma can be generated only inside the tube and the inside of the tube can be coated with an organic film. Also, by controlling the pressure, the bundled polymer tubes can be collectively processed.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a schematic configuration of a plasma polymerization apparatus to which the present invention is applied.

[Explanation of symbols] 1 reaction tube 2 tube 3 joint 4 gas introduction / exhaust 5 vacuum evacuation device 6 gas introduction 7 coil 8 matching device 9 high frequency power supply

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location D01D 5/24 B 7199-3B D06M 10/10

Claims (5)

[Claims] 1. An inner diameter of 0.01 mm in a cylindrical reaction tube 1.
~ 3mm tube or bundle of tubes 2
Is installed, and a pressure difference is provided at both ends of the tube to allow gas to flow inside. At this time, the reaction tube inner diameter R (mm) and the tube inner diameter r
(Mm), high pressure side pressure P ^H in (Torr) inside the tube, low pressure side pressure P ^L in (Torr), pressure outside the tube P out (To
rr), and 4.5 × 10 ^-2 / r <P ^L in <P ^H in <P out or 4.5 × 10 ^-2 / r <P ^L between the total cross-sectional area S (mm ² ) of the tube Under the pressure condition satisfying any of in <P ^H in and Pout <4.5 × 10 ⁻² / (R−2π ^−1/2 S ^1/2 ), the organic compound in the space inside the tube 2 is A method of coating the inner surface of the tube with a plasma-polymerized substance of an organic substance by plasma-converting a non-polymerizable gas with a plasma. 2. The tube according to claim 1, wherein the organic compound polymerized by the plasma is a gas, and a mixed gas of the organic gas and the non-polymerizable gas is turned into plasma inside the tube. Inner surface coating method. 3. The tube inner surface coating method according to claim 1, wherein the organic compound that is polymerized by the plasma is applied to the inner surface of the tube in advance, and the non-polymerizable gas is turned into plasma inside the tube. 4. The method for coating an inner surface of a tube according to claim 1, wherein the inner surface of the tube is previously treated with the plasma of the non-polymerizable gas, and then the polymerized organic compound is introduced into the tube. 5. The tube 2 coated with the plasma polymerized material is a hollow fiber membrane having a function of separating molecules by adsorption and diffusion, and the tube 2 is bundled and coated on the inner surface at once. The tube inner surface according to any one of claims 1 to 4, wherein the bundled ends of the hollow fiber membrane are fixed with a resinous substance, and the hollow mouth is a hollow fiber separation membrane module having openings at both ends. Coating method.