KR101412644B1 - Gas exhaust pump system and gas exhaust method - Google Patents

Abstract

Provided is a gas exhaust system capable of suppressing the incorporation of seal gas into the process gas and reducing the amount of seal gas used. The gas exhaust pump system according to the present invention has a body pump and a sub-pump. The main body pump includes a screw shaft, a rotation shaft engaged rotatably with the rotation driving means for rotating the screw rotor, pinching means for pinching the rotational shaft so as to be rotatable, lubricating oil supply path having a lubricant port for the pinching means, A seal member which is bridged between the rotary shaft and the seal housing over the entire circumference of the rotary shaft, and a seal member which is provided between the rotary shaft and the seal housing, A seal gas supply path having a supply port for supplying a seal gas and a seal gas exhaust path having a seal gas suction port for exhausting the seal gas from the gap to the outside of the main pump. The sub-pump is a pump for reducing the pressure of the seal gas exhaust passage.

Description

TECHNICAL FIELD [0001] The present invention relates to a gas exhaust pump system and a gas exhaust method,

The present invention relates to a manufacturing apparatus for an electronic device (hereinafter referred to as " semiconductor application electronic device ") using a semiconductor related technology such as a semiconductor device and a liquid crystal display device, a solar cell, an organic EL device, , And a gas exhausting pump system and a gas exhausting method used in an apparatus for manufacturing electronic parts for electronic devices.

BACKGROUND ART [0002] Conventionally, as a gas exhaust pump capable of continuous operation at a high speed and a long time, for example, a volume transfer type screw pump having a pair of screw rotors in a housing is known (see Non-Patent Document 1). Among them, since it is possible to exhaust a wide range from a molecular watershed to a viscous watershed, has a uniform exhaust velocity without selecting a gas type, and has a high arrival pressure, a low- We are waiting for the establishment of mass production technology for anger and commercialization by it.

On the other hand, in a manufacturing apparatus or a production system for manufacturing functional devices such as a semiconductor device, a display device using a liquid crystal or an organic EL, or a solar battery device, a variety of pumps Many are used. Since the pump has a wide application range of the reduced pressure and the exhaust performance does not depend on the type of the exhaust gas, for example, the pump is changed for each gas type, and the pump is arranged corresponding to the change of the pressure condition. There is no need to prepare a suitable pump for each discharge position in the production system. If it does not depend on the exhaust speed, the same kind of pump can be used, and there is no inconvenience of selecting a pump for each exhausting position. If the low-cost pump is commercialized in the above-mentioned type, the degree of diffusion becomes remarkable, and it is expected to contribute greatly to the development of industry.

1 is a schematic explanatory diagram of an example of the pump. 1 includes a female screw rotor 101 and a male screw rotor 102 having an unequal lead / uneven angle of inclination. Both screw rotors 101 and 102 form a screw-and-male fixture engaging portion 104 by engaging teeth and grooves by providing a desired clearance for obtaining a safe and smooth rotational motion. When the male and female screw rotors 101 and 102 are fixed to the respective rotary shafts (the rotary shaft of the female screw rotor is not shown in the drawing and the rotary shaft of the male screw rotor is fixed to the female rotary shaft 105), the engaged state is maintained. Both rotors 101 and 102 are accommodated in the stator 106 by making a predetermined gap between the tip of the jig and the inner wall of the stator 106. [

The rotary shaft 105 is rotatably supported on the bearing body 116 via a nipping means, for example, specifically, an angular bearing 107 (four of 107a, 107b, 107c and 107d are shown for convenience) Respectively. The male screw rotor 102 is attached to the rotating shaft 105 and rotates by the rotation of the rotating shaft 105. A lubricating oil supply path 109 is provided in the rotary shaft 105. The lubricating oil 111 is stored in the lubricating oil storage portion 112 provided at a predetermined position below the base plate 110. When the rotary shaft 105 is rotated by a rotation force of a motor (not shown) via a rotary gear (not shown), the lubricating oil 111 sucks up the lubricating oil supply path 109 by the centrifugal force due to the rotation, And poured into the angular bearing 107.

The oil seal member 113 for preventing the lubricant oil from diffusing through the gap between the rotary shaft 105 and the seal housing 108 so as not to diffuse to a portion other than the angular bearing 107, And is provided around the entire circumference of the rotary shaft 105 to seal the gap between the rotary shaft 105 and the seal housing 108. The seal gas such as N ₂ is supplied to the gap between the rotary shaft 105 and the seal housing 108 through the seal gas supply passage 114 because the oil seal member 113 alone is assumed to be insufficient. The lubricating oil itself or its vapor is prevented from diffusing to the upstream side of the vacuum system. The seal gas is supplied from the seal gas supply path 114 and is exhausted to the outside from a discharge path (not shown) together with a gas used in a semiconductor process such as film formation or etching through a predetermined flow path.

Nowadays, in view of environmental restoration and reuse of resources, exhausted gas is sent to a reuse treatment system of the gas resources and reused.

The screw pump shown in Fig. 1 has a pair of (twin) screw rotors. However, when there is one screw rotor and a gap is provided between the end face of the teeth of the screw rotor and the inner wall surface of the stator, (See Japanese Patent Application Laid-Open No. 2001-3258). The screw pump of the single screw rotor performs exhausting by rotating the screw pump. In this type of pump, a sealing gas is used to prevent the diffusion of lubricating oil for continuously and continuously rotating the rotary shaft at high speed.

Japanese Patent Application Laid-Open No. 6-81788

"Innovative Manufacturing Technology in Semiconductor and Display Industry (Award)", Technology Alliance Group, pp.443-447

However, since a pressure difference is generated between the upstream side and the downstream side of the seal gas passage along the oil seal member 113 as a boundary, the seal gas is divided by the pressure difference between the upstream side and the downstream side As the pressure difference increases, the amount of gas flowing into the upstream side increases accordingly. When the downstream side is communicated with the external atmospheric pressure at the portion of the discharge passage 115, the pressure difference becomes maximum, and the seal gas amount flowing into the upstream side with a low pressure is also maximized. That is, the mixing ratio of the seal gas to the process gas in the pump is maximized. Of course, the higher the degree of vacuum on the upstream side, the larger the value of the mixing ratio.

As one of the methods for reducing the amount of seal gas flowing on the upstream side, a gap between the rotary shaft 105 and the seal housing 108 is narrowed so as to reduce the conductance of the gap space, I have an idea to have a car.

However, the width of the clearance between the rotary shaft 105 and the seal housing 108 needs to be secured to a certain extent or more in terms of the safety of rotation in terms of machining accuracy and expansion due to heat generated during operation . In order to secure the safety of the rotation by the width of the gap, a margin is required for the width of the gap as the rotation speed of the rotation shaft 105 increases. If the width of the gap is widened, the flow rate of seal gas per unit time increases, and the amount of seal gas flowing into the screw pump increases. In this case, the recovery efficiency of the reusing treatment of the expensive gas resources used in the process is lowered and the production cost is increased, which leads to an increase in the cost of the entire production system of the semiconductor device or the functional device.

Particularly, when the production system includes the rare gas reuse system such as Xe and Kr gas, the reuse cost is remarkably increased. From this point, the above-described method does not solve the appropriate problem in order to further reduce the amount of seal gas flowing into the screw pump.

An object of the present invention is to provide a gas exhaust pump system and a gas exhaust method capable of suppressing mixing of a seal gas into a process gas and reducing the use amount thereof .

In order to achieve the above object, a first aspect of a gas exhaust pump system according to the present invention is a gas exhaust pump system having a main body pump and a sub pump, wherein the main body pump includes a screw rotor, A rotating shaft which is formed integrally with the screw rotor or which is rotatably engaged with the rotation driving means for rotating the screw rotor, a holding means for holding the rotating shaft so as to be rotatable, A seal housing which covers a periphery of a portion of the rotating shaft which is not held by the holding means with a predetermined gap between the outer peripheral surface of the rotating shaft and the lubricating oil supply passage,

A seal member which is bridged between the rotary shaft and the seal housing over the entire circumference of the rotary shaft to prevent the lubricating oil poured into the holding means from intruding into the exhaust system space of the main pump through the gap; And a seal gas exhaust path having a seal gas intake port for exhausting seal gas supplied to the gap from the gap to the outside of the main body pump, And the pump is a pump for reducing the pressure of the seal gas exhaust passage.

In a second aspect of the present invention, there is provided a gas exhaust pump system according to the first aspect, wherein at least one of the outer circumferential surface of the rotary shaft and the inner circumferential surface of the seal housing has a perfluoroalkoxyalkane ( Hereinafter referred to as " PFA ").

[Number 1]

(구조식1)

(Structural formula 1)

Rf: perfluoroalkyl group,

m and n are positive integers.

That is, the PFA of the present invention is a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether including the structure as shown in the structural formula (1). Examples of Rf include an alkyl group having two or more fluorine atoms, for example, a fully fluorinated alkyl group. The carbon number of Rf is not particularly limited, but is 1 or more, preferably 2 or more, usually 12 or less, preferably 6 or less. The weight average molecular weight of the PFA of the present invention is not particularly limited, but preferably satisfies the melting point and density characteristics as described later.

The third aspect of the gas exhaust pump system according to the present invention is a gas exhaust pump system having a main pump and a sub pump, wherein the main pump includes a rotor and a rotor, A rotating shaft for rotatably engaging with the rotary driving means for rotating the rotor; a holding means for holding the rotating shaft so as to be rotatable; and a gas supply port for lubricating the holding means at one end A sealing housing which covers a periphery of a portion of the rotating shaft not held by the holding means with a predetermined gap between the rotating shaft and the outer peripheral surface of the rotating shaft; And a lubricating oil that is bridged with the housing and poured into the nipping means is discharged through the gap A seal gas supply passage having a supply port for supplying a seal gas to the gap, a seal gas for discharging the seal gas supplied to the gap from the gap to the outside of the main pump, And a seal gas exhaust passage having a gas suction port, wherein the sub pump is a pump for reducing the pressure of the seal gas exhaust passage.

A fourth embodiment of the gas exhaust pump system according to the present invention is characterized in that in the third embodiment, at least one of the outer circumferential surface of the rotary shaft and the inner circumferential surface of the seal housing has a PFA film of the structural formula 1 .

A first aspect of the gas exhaust method according to the present invention is a gas exhaust method using a gas exhaust pump system having a main pump and a sub pump, wherein the main pump is capable of reducing the pressure in the process chamber to atmospheric pressure or less A rotary shaft which is engaged with the screw rotor or integrally formed with the screw rotor and which is rotatably engaged with a rotary drive means for rotating the screw rotor, A lubricating oil supply path having a lubricating oil supply port for lubricating the lubricating oil at one end thereof and a lubricating oil supply path for lubricating the lubricating oil supply path at a predetermined gap with respect to the outer circumferential surface of the rotating shaft, A seal housing covering a periphery of a portion not held by the shaft, A seal member bridged between the rotary shaft and the seal housing to prevent the lubricating oil poured into the holding means from intruding into the exhaust system space of the main pump through the gap; A seal gas supply passage having a sphere on the upstream side of the seal member and a seal gas suction port for discharging a seal gas supplied to the gap from the gap to the outside of the main pump on the downstream side of the seal member, Wherein the sub-pump is in a connection relation with the seal gas exhaust passage for reducing the seal gas exhaust passage, and when the gas exhaust pump system is operated, the exhaust operation of the main pump and the sub- And a step of interlocking the decompression operation of the pump.

The second aspect of the gas exhausting method according to the present invention is a gas exhausting method using a gas exhaust pump system having a main pump and a sub pump, wherein the main pump is capable of reducing the pressure in the process chamber to atmospheric pressure or less A rotary shaft which is rotatably engaged with a rotary drive means for rotating the rotor, the rotary shaft being connected to the process chamber and having a rotor, a rotary shaft integrally formed with the rotor or integrally formed with the rotor, A lubricating oil supply path having a lubricating oil supply port at one end for lubricating the lubricating oil in the holding means and a lubricating oil supply path which is not sandwiched by the holding means of the rotating shaft at a predetermined gap with the outer circumferential surface of the rotating shaft A seal housing covering the periphery of the rotary shaft and the seal housing, A sealing member bridged between the sealing member and the sealing member to prevent the lubricating oil poured into the holding means from intruding into the exhaust system space of the main pump through the gap; And a seal gas exhaust passage having a seal gas suction port on the downstream side of the seal member for exhausting a seal gas supplied to the gap from the gap to the outside of the main pump, The sub-pump is in a connection relationship with the seal gas exhaust passage for reducing the seal gas exhaust passage, and when the gas exhaust pump system is operated, the exhaust operation of the main pump and the decompression operation of the sub- And a step of controlling the display device.

According to the present invention, it is possible to suppress the incorporation of the seal gas into the process gas and to reduce the amount of the seal gas. Therefore, it is possible to improve the gas recovery efficiency in the gas resource re- The cost of the entire production system can be reduced.

1 is a schematic view for explaining an example of a screw pump according to the present invention.
2 is a schematic explanatory diagram of an example of a pump system for gas exhaust for explaining the present invention.
Fig. 3 is a diagram showing a measurement area of smoothness in Experiment 1. Fig.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

2 is a schematic explanatory diagram of an example of a gas exhaust pump system for explaining the present invention. The screw pump (body pump) shown in Fig. 2 is essentially the same as the screw pump shown in Fig. 1, so that parts common to those of Fig. 1 are assigned the same numbers. The uni-lead / uneven-angle screw gas exhaust pump (main pump) 100 shown in Fig. 1 has a male screw rotor 101 and a male screw rotor 102 having a unequal lead / unequal inclination angle. Both screw rotors 101 and 102 are provided with a desired clearance for the purpose of obtaining a safe and smooth rotational motion and engage the fixture to form the screw-male fixture engaging portion 104. When the male and female screw rotors 101 and 102 are fixed to the respective rotary shafts (the rotary shaft of the female screw rotor is not shown in the drawing, and the rotary shaft of the male screw rotor is fixed at 105), the engaged state is maintained. Both rotors 101 and 102 are accommodated in the stator 106 by forming a predetermined gap 117 between the tip of the jig and the inner wall of the stator 106.

The rotary shaft 105 is held so as to be rotatable by the holding means. In the body pump 100 shown in Fig. 2, the holding means includes, for example, an angular bearing 107 (four of 107a, 107b, 107c, and 107d are shown for convenience) and a bearing body 116 ). The male screw rotor 102 is attached to the rotating shaft 105 and rotates by the rotation of the rotating shaft 105.

A lubricating oil supply path (oil supply path) 109 having a lubricating oil port 213 for lubricating the angular bearing 107 is provided in the rotary shaft 105. The lubricating oil 111 is stored in the lubricating oil storage portion 112 provided at a predetermined position below the base plate 110. When the rotary shaft 105 is rotated by a rotation force of a motor (not shown) via a rotary gear (not shown), the lubricating oil 111 sucks up the lubricating oil supply path 109 by the centrifugal force due to the rotation, And poured into the angular bearing 107.

The oil seal member 113 for preventing lubricant diffusion prevents the lubricating oil 111 from diffusing to a portion other than the angular bearing 107 through the gap 117 between the rotary shaft 105 and the seal housing 108, Is provided around the entire circumference of the rotary shaft 105 to seal between the rotary shaft 105 and the seal housing 108 as shown in Fig. That is, the seal member 113 is located above the oil port 213 in order to prevent the component of the lubricating oil poured into the holding means from penetrating into the exhaust system space (screw side exhaust system space) of the pump body through the gap 117 And is bridged between the rotary shaft 105 and the seal housing 108 over the entire circumference of the rotary shaft 105.

The sealing gas such as N ₂ gas is supplied to the gap between the rotary shaft 105 and the seal housing 108 through the seal gas supply passage 114 as shown by the arrows in the figure because the oil seal member 113 alone is assumed to be insufficient. The lubricating oil itself or its vapor is prevented from diffusing from the upstream side (upstream side from the screw side exhaust system space) of the vacuum system.

The supply of the seal gas to the gap 117 and the discharge of the seal gas from the gap 117 are performed by supplying the seal gas supply port 215 for supplying the seal gas to the gap 117 from the seal member 113 upstream And a seal gas inlet 214 at the downstream side of the seal member 113 for exhausting the seal gas supplied to the gap 117 to the outside of the pump body. It can be done through the exhaust path.

The seal gas supplied from the seal gas supply passage 114 and flowing to the upstream side of the gap 117 flows through a predetermined flow path (a screw side exhaust system space of the main pump 100) (Not shown) together with the gas to be used. The seal gas supplied from the seal gas supply passage 114 and flowing to the downstream side of the gap 117 is sent to the exhaust system (not shown) from the exhaust port 208 after passing through the seal gas exhaust path 201 .

The screw pump 100 is provided at the downstream side of the seal gas discharge path 115 with a sealing gas exhausting mechanism having an exhaust port 208 at the end thereof, which is made of, for example, stainless steel pipe, And is connected to the path 201.

A valve 204 composed of a sub-pump 202, a pressure gauge 203, a needle valve or the like, a flow meter 205, a pressure gauge 206 And an oil trap 207 are provided. The exhaust port 208 is connected to an exhaust gas treatment system.

The oil trap 207 traps the component of the lubricating oil that invades the seal gas exhaust passage 201 through the seal gas discharge passage 115 when the stopper 209 is not present, Thereby preventing the components of the lubricating oil from flowing. Therefore, the components of the lubricating oil are not mixed with the exhaust gas exhausted to the exhaust gas processing system, and the exhaust gas can be smoothly separated. In the presence of the cap 209, the oil trap 207 is essentially not required.

The stopper 209 allows the downstream side of the seal gas discharge path 115 to pass through the original exhaust path space of the pump 100 (the screw side exhaust system space of the body pump 100) The pressure difference between the upstream side and the downstream side of the upstream side and the downstream side. When the plug 209 is opened, the lubricating oil enters the seal gas discharge path 115 and mixes with the discharged seal gas. Normally, the plug 209 is in a closed state.

The gas exhaust pump system shown in Fig. 2 can adjust the pressure difference between the upstream side and the downstream side of the seal member 113 by adjusting the displacement of the screw pump 100 and the sub-pump 202. The pressure difference between the upstream side and the downstream side of the seal member 113 can be made small and the seal member 113 can be made compact. The amount of the seal gas flowing on the upstream side of the seal gas can be relatively reduced.

As one of the methods for reducing the amount of seal gas flowing on the upstream side, a gap between the rotary shaft 105 and the seal housing 108 is narrowed so as to reduce the conductance of the gap space, Although the idea of having a car is described first in terms of machining precision, it is difficult to realize it, but a solution to the problem solved by the present applicant as a separate solution totally different from that by machining precision has been proposed in the previous application. By combining this solution with the present invention, the effect of the present invention can be further enhanced. This point will be described below.

The configuration of the shaft sealing mechanism of the gas exhaust pump system according to the present invention will be described below with reference to FIG. The shaft seal mechanism according to the present invention comprises a rotary shaft 105 and a seal housing 108. The rotary shaft 105 and the seal housing 108 are installed by making a predetermined gap 117. A PFA film is provided on the outer surface (outer wall surface 211) of the rotary shaft 105 or / and the inner surface (inner wall surface 210) of the seal housing 108 (in FIGS. 1 and 2, An example in which the PFA film 212 is provided on the inner surface is shown).

The PFA film 212 provided on the surface of at least one of the rotary shaft 105 and the seal housing 108 (both of which are referred to as " shaft sealing mechanism constituent members ") has at least a shaft seal mechanism member After the PFA is coated on the wall surface forming the gap 117, it is formed by the process of melting and re-melting so that a high smoothness is given to the free surface.

The PFA employed in the present invention is manufactured and sold by many companies. Among them, PFA having a melting point of 298 to 310 캜 and a density of 2.12 to 2.17 is preferably used in the present invention. When it is necessary to consider the use at a high temperature, it is preferable that the maximum continuous use temperature is preferably at least 260 캜.

When it is necessary to consider heat radiation such as an exothermic reaction, it is preferable that the thermal conductivity is, for example, 0.25 W / m · k or more.

The melt viscosity of PFA is an important factor for forming a film having high surface smoothness and no bending. If the melt viscosity is too high, it becomes difficult to obtain high surface smoothness and bending easily occurs. The melt viscosity of the PFA in the present invention is preferably 10 g / 10 min or more, and more preferably 20 g / 10 min or more, in accordance with ASTM D3307. Of course, if the coating is made uniform and the melting time is sufficiently taken, a PFA film having high surface smoothness without bending can be obtained even with a somewhat high melt viscosity.

Specifically, the following PFA is preferably employed.

(1) Manufactured by Daikin Industries, Ltd.

AC-5539 (Electrostatic paint thick powder)

Examples of the AC series include AC-5600, ACX-21, ACX-31, ACX-31WH, ACX-34 and ACX-41.

In addition, AD-2CRE (coating film thickness: 10 to 15 占 퐉) and AW-5000L (coating film thickness: 30 to 40 占 퐉) can be used. The manufacturer recommends that AD-2CRE be painted with wire mesh of 100 to 150 mesh and AW-5000L with painted wire mesh of 60 to 80 mesh after filtration. The coating condition of the AD-2CRE is preferably an air spray condition of a spray gun having a nozzle diameter of 1.0 mm and a fogging pressure of 0.2 MPa. The coating condition of the AW-5000L is preferably an air spraying condition of a spray gun having a nozzle diameter of 1.0 to 1.2 mm and a fogging pressure of 0.2 to 0.4 MPa.

Examples of the primer which is preferably used in the present invention include those listed below. As the primers of the aqueous system, TC-1509M1, EK-1909S21L, EK-1909S21L, EK-1959S21L, EK-1983S21L, EK-1208M1L, EK-1209BKEL, EK-1209M1OL and EK- , TC-1559M2, and TC-11000.

For example, when the primer is EK-1909S21L, these primers are roughened with Tosa Emery Extra # 80 / # 100 = 50 · 50 manufactured by UJI electrochemicalsystem, It is painted with air spray. A PFA film is provided thereon.

The coating conditions of the primer coating are, for example, 1.0 to 1.2 mm in nozzle diameter of spray gun, 0.2 to 0.4 MPa in fogging pressure, 1.0 to 1.5 mm in nozzle diameter of spray gun, and 0.2 to 0.3 MPa in fogging pressure. Drying is carried out, for example, at a temperature of 80 to 90 ° C and a time of 10 to 15 minutes.

(2) Mitsui & DuPont Fluro Chemical Co.

EM-500CL (for water-based topcoat), EM-500GN (for aqueous topcoat), EM-700CL (for aqueous topcoat), EM-700GN , And these are suitable for articles which can not be electrostatically coated because of their complicated shape.

In addition, MP-102 (micro powder, top coat), MP-103 (micro powder, top coat), MP-300 (fluorinated powder, top coat) MP-622 (conductive powder), MP-620 (conductive powder), MP-620 (high thermal conductivity), MP-621 MP-502 (suitable for articles that can not be electrostatically coated because of complex shapes), MP-501 (suitable for articles that can not be electrostatically coated because of complex shapes), MP-502 , SL-800BK (including carbon filler), SL-800LT (including glass filler), and the like.

Of these, MP-103, MP-300 and MP-310 are preferred in the present invention because the resulting film is excellent in plane smoothness. Especially, MP-310 is particularly preferable because it is excellent in control of the Chinese New Year, about 5 占 퐉 and micro-uniformity.

SL-800BK is preferable in the present invention in terms of heat dissipation because it has good thermal conductivity and excellent heat dissipation. MP-630 and 642 (conductive micropowder) are also preferable PFA materials in the present invention in terms of good thermal conductivity and excellent heat dissipation.

Among these PFAs of Mitsui Dupont Fluoro Chemicals Ltd., particularly preferred are those wherein Rf in the structural formula 1 is a PFA of -CF 2 CF 2 CF 3, the molecular weight is several hundred thousand to one million, the melting point is 300 to 1,000,000, 310 ° C, viscosity: 104 to 105 poise (380 ° C), and maximum continuous operating temperature: 260 ° C.

As the primer, a PFA primer PL-902 series sold as a general aqueous general purpose primer and a PFA primer PL-910 series sold as a primer having excellent heat resistance and corrosion resistance are preferable. Specifically, they are sold under the trade names of PL-902YL, PL-902BN, PL-902AL, PL-910YL, PL-910BN, PL-910AL and PL-914AL.

(3) Packing Land Co., Ltd.

(Lubricating, antistatic, standard film thickness 100, 300 占 퐉, heat resistance temperature 260 占 폚), NK-013 and 013C (lubricity, standard film thickness 50 占 퐉, heat resistance temperature 260 占 폚) Abrasion, standard film thickness 300 mu m, heat-resistant temperature 150 DEG C).

(4) Made by Japan Fluorine Industry Co., Ltd.

NF-015 (standard film thickness 50 탆), NF-015EC (standard film thickness 40 탆, antistatic) and NF-020AC (standard film thickness 600 탆, antistatic).

As the base material to be processed in the shaft sealing mechanism member in the present invention, preferably, a metal such as an aluminum-based metal such as stainless steel, aluminum, or an aluminum alloy, which has good thermal conductivity and is suitable for processing, Basic materials are employed.

In the screw pump according to the present invention, the rotary shaft and the seal housing are engaged with the rotary shaft through the angular bearing so as to be rotatable. However, when high-speed rotation is maintained for a long time, frictional heat is generated between the rotary shaft and the angular bearing, It is preferable to select a base material having a good thermal conductivity in order to further increase the heat dissipation effect of the housing.

As the base material, it is preferable to select an aluminum-based metal from a lightweight material, but it is preferable to select one having a hardness and a small thermal expansion coefficient as much as possible. As a base material made of aluminum, an aluminum alloy containing pure metals and other metals is employed in the present invention.

The aluminum alloy in the present invention is made of a metal mainly composed of aluminum. The metal containing aluminum as a main component is a metal containing aluminum in an amount of usually 50 mass% or more, preferably, the metal contains 80 mass% or more of aluminum, more preferably 90 mass% or more, It is preferable that the content of the binder is 94 mass% or more.

As a preferable metal contained in the aluminum alloy, there may be mentioned at least one or more metals selected from the group consisting of magnesium, titanium and zirconium. Among them, magnesium is particularly preferable because it has the advantage of improving the strength of the aluminum alloy.

In the present invention, the aluminum alloy may be a metal whose main component is high-purity aluminum whose content of specific elements (iron, copper, manganese, zinc, chromium) is suppressed. The total content of these specific elements is preferably 1.0 mass% or less, more preferably 0.5 mass% or less, further preferably 0.3 mass% or less.

The aluminum alloy containing high-purity aluminum as a main component may contain at least one kind of other metal capable of forming an alloy with aluminum, if necessary. Such a metal is not particularly limited as long as it is other than the above-mentioned specific elements, and preferable metals include at least one kind of metal selected from the group consisting of magnesium, titanium and zirconium. Among them, magnesium is particularly preferable because it has the advantage of improving the strength of the aluminum alloy. The magnesium concentration is not particularly limited as long as it is in a range capable of forming an alloy with aluminum, but it is usually 0.5 mass% or more, preferably 1.0 mass% or more, more preferably 1.5 mass% or more do. In order to form a uniform solid solution with aluminum, it is preferably 6.5 mass% or less, more preferably 5.0 mass%, further preferably 4.5 mass% or less, and most preferably 3 mass% or less.

The aluminum alloy in the present invention may contain other metal components as other crystal adjustment agents of the above-mentioned metals. Is not particularly limited as long as it has a sufficient effect on crystal control, but zirconium and the like can be preferably used.

In the present invention, the content of each metal other than aluminum positively contained in the aluminum alloy is usually 0.01 mass% or more, preferably 0.05 mass% or more, more preferably 0.05 mass% or more, , And 0.1 mass% or more. The lower limit of this content is necessary for sufficiently expressing the characteristics of the contained metal. However, it is usually 20 mass% or less, preferably 10 mass% or less, more preferably 6 mass% or less, particularly preferably 4.5 mass% or less, and most preferably 3 mass% or less. This upper limit is necessary for the metal components other than aluminum and aluminum to become a uniform solid solution and to maintain good material properties.

As a base material made of stainless steel, SUS316 is preferable for the corrosion resistance, SUS316L for the low carbon steel, and SUS316L-EP whose surface is mirror finished beforehand by electrolytic polishing, It is not limited to these basic materials. For example, when hardness is important, iron-based materials such as SCM and S45C are also used.

The base material (also referred to as a " processed member ") that is processed as a shaft sealing mechanism member for a screw pump according to the present invention has a PFA film for forming a wall surface constituting a passage of seal gas, The mounting surface is preferably subjected to smoothing by means of electrolytic polishing, mechanical polishing, or both polishing so as to give a desired smoothness. It is preferable that the smoothness of the polishing surface at this stage is preferably not more than the average particle size of the PFA powder when the powder of PFA is electrostatically coated on the polishing surface. However, the case where the PFA film is not directly provided on the polishing surface of the base material is not limited to this.

In order to facilitate and secure the smoothness and the film quality of the free surface of the PFA film to be formed, a film made of Al ₂ O ₃ or Ni or NiF ₂ (referred to as a "base film" It is preferable to install the film on the mounting surface.

Since the effect of suppressing pyrolysis of PFA is great when a film composed of Ni or NiF ₂ is provided on the PFA film surface of the base material in advance and then the PFA film provided thereon is melted or remelted, A film having good quality can be obtained even if the melting temperature is set higher.

Further, since the Ni film has high corrosion resistance and high adhesiveness to the PFA film, it is preferable as the base film of the PFA film. In order to arrange the Ni film on the PFA film surface of the base material (the member to be processed), for example, electroless nickel plating and plasma sputtering in which Ni is sputtered are used. Otherwise, MOCVD using an organic complex of Ni It can also be adopted. In the electroless nickel plating method, the plating solution contains a reducing agent, but P (phosphorus) or B (boron) may be contained in the resulting Ni film by the reducing agent to be used. When hypophosphite is used as the reducing agent, P (phosphorus) can be contained in the Ni film to be obtained, and B (boron) can be contained in the Ni film by using dimethylamine borane (DMAB). When B (boron) is contained in the Ni film, the hardness of the film can be increased and the electrical resistance of the film can be lowered as compared with the case where P (phosphorus) is contained in the Ni film, . The use of hydrazone as a reducing agent is advantageous because hydrogen gas is not generated during the reaction, unlike hypophosphorous acid or DMAB.

The amount of P (phosphorus) contained in the Ni film is appropriately determined depending on the use of the reaction vessel, but it is preferably from 83 to 98% of Ni, from 2 to 15% of P, %.

In the case of B (boron), in terms of chemical composition, it is preferable that Ni: 97 to 99.7%, B: 0.3 to 3%, and others: 0 to 2.7%.

Since the electroless nickel plating solution itself is commercially available and can be combined with itself, it may be performed by itself, but the object of the present invention can be achieved by processing the third electroless nickel plating solution by a third party. Commercially available electroless nickel plating solutions are manufactured or sold, for example, from Tool System Co., Ltd., World Metal Co., Ltd., Metal Processing Technology Research Institute Co., Ltd., Okuno Pharmaceutical Industry Co., Ltd., Uemura Industry Co., have. Examples of companies that conduct electroless nickel plating processing include Kanigen Co., Ltd., Hitachi Sengyo Engineering Co., Ltd., Sanwa Plating Industry Co., Ltd., Kodama Co., Ltd., Shimizu Chuo Metal Co., Ltd., Yamato Electric Industrial Co., Ltd., Nishina Industrial Co., Ltd., and Tohma Refining Co., Ltd., and the like.

In order to provide the NiF ₂ film on the PFA film mounting surface of the member to be processed, the free surface of the Ni film provided on the PFA film mounting surface of the member to be processed may be fluorinated. In the fluorination treatment, for example, a base material provided with a Ni film on its surface is set in a vacuum container, and after reaching a predetermined degree of vacuum, F ₂ gas is supplied into the vacuum container to expose the surface of the Ni film to F ₂ gas. In this case, the entire Ni film may be formed into a NiF ₂ film by controlling the time to be exposed to the F ₂ gas, or a two-layer structure in which the Ni film is formed at the bottom and the NiF ₂ film is formed at the top. Alternatively, it is possible to change the distribution of F atoms in the thickness direction of the film. For example, it is also possible to continuously reduce the distribution amount of the F atoms in the film from the free surface toward the lower side of the film. In this case, the adhesion to the base material and the adhesion to the PFA film can be further strengthened. Of course, as described above, the NiF ₂ film obtained by fluorinating an Ni film containing P (phosphorus) or B (boron) has P (phosphorus) or B (boron) Needless to say.

When the Ni film and the Ni film are provided as a base film, the electroless plating process is followed by annealing for a desired time at a desired temperature in an atmosphere such as a rare gas or a nitrogen gas, Since the adhesion and hardness can be greatly increased, this method is the preferred bottom film post-treatment method in the present invention.

In the present invention, it is preferable to carry out annealing for about 1 hour in a temperature range of 260 to 350 캜 in a nitrogen atmosphere, for example.

Even when an Al ₂ O ₃ film is provided as a base film on the PFA film-mounting surface of a member to be processed made of an aluminum alloy, an anodic oxidation method capable of forming a non-porous Al ₂ O ₃ film is preferable. The film formed by the anodic oxidation method is formed at least on the PFA film surface of the member to be processed by the anodic oxidation method described later. The Al ₂ O ₃ anodic oxide film is a film made of an oxide of a metal containing aluminum as a main component and can easily form a film having a thickness of 10 nm or more. Since this film is a passive film, it is formed on a predetermined surface of the aluminum alloy shaft seal mechanism constituting member and exhibits high performance as a protective film.

The film thickness of the Al ₂ O ₃ anodic oxide film is preferably 100 탆 or less. If the film thickness is large, cracks tend to occur, and outgas is easily released. Therefore, the thickness of the Al ₂ O ₃ anodic oxide film is more preferably 10 μm or less, more preferably 1 μm or less, still more preferably 0.8 μm or less, particularly preferably 0.6 μm or less. The lower limit of the film thickness is preferably 10 nm or more. If the film thickness is too thin, sufficient corrosion resistance can not be obtained. The film thickness of the Al ₂ O ₃ anodic oxide film is more preferably 20 nm or more, and still more preferably 30 nm or more.

The non-porous Al ₂ O ₃ film in the present invention is a thin film and excellent in corrosion resistance with respect to a porous Al ₂ O ₃ film having a porous structure that has been conventionally used and has no or little pores or pores (Since they do not have substantially), there is an advantage that they are not adsorbed or hardly adsorbed.

The Al ₂ O ₃ anodic oxide film is obtained by anodizing a predetermined surface of an aluminum alloy shaft seal mechanism component using a chemical solution having a pH of 4 to 10. According to this method, there is an advantage that a dense, non-porous anodic oxidation film can be easily obtained.

Further, this method has a function of restoring defects due to nonuniformity of the metal surface, and thus has an advantage that a dense and smooth anodic oxide film can be formed. The lower limit of the pH value of the chemical liquid is preferably 4 or more as described above, but is preferably 5 or more, and more preferably 6 or more. The upper limit of the pH value of the chemical liquid is usually 10 or less, preferably 9 or less, and more preferably 8 or less. In order to reliably prevent dissolution of the Al ₂ O ₃ anodic oxide film formed by the anodic oxidation into the chemical solution, it is preferable to set the pH value to a pH value close to neutral or neutral or a pH value as close as possible to neutrality Do.

In the present invention, the chemical liquid is preferably in the range of pH 4 to 10 in order to buffer the concentration fluctuation of various substances in the anodic oxidation to maintain the pH within a predetermined range (buffering action). Therefore, it is preferable to include a compound such as an acid or a salt which exhibits a buffering action (hereinafter sometimes referred to as " compound (A) "). The kind of such a compound is not particularly limited, but is preferably at least one member selected from the group consisting of boric acid, phosphoric acid and organic carboxylic acid and salts thereof from the viewpoint of high solubility in a chemical liquid and good solubility stability. More preferably, it is an organic carboxylic acid or a salt thereof having little residual boron and phosphorus elements in the anodic oxidation film.

The concentration of these compounds (A) may be suitably selected in accordance with the intended use, but is generally 0.01% by mass or more, preferably 0.1% by mass or more, and more preferably 1% by mass or more based on the entire chemical conversion liquid. It is preferable to increase the electric conductivity so as to sufficiently form the anodic oxide film. However, it is usually 30 mass% or less, preferably 15 mass% or less, and more preferably 10 mass% or less. In order to keep the performance of the anodic oxide film high, or to suppress the cost, 10 mass% or less is preferable.

The chemical liquid in the present invention preferably contains a non-aqueous solvent. The use of a chemical liquid containing a non-aqueous solvent has an advantage of being able to be processed with a high throughput because the time required for the constant current is shortened as compared with the chemical liquid in the aqueous system. In addition, when an aqueous solution is used as a chemical conversion solution, it is preferable to use a main solvent having a small dielectric constant capable of suppressing electrolysis of water, since OH ions generated by electrolysis of water are etched to make the anodic oxide film porous.

The nonaqueous solvent is not particularly limited as long as it is capable of anodic oxidation well and has sufficient solubility to the solute. However, it is preferable to use a solvent having at least one alcoholic hydroxyl group and / or at least one phenolic hydroxyl group or an aprotic organic solvent . Among them, a solvent having an alcoholic hydroxyl group is preferable from the viewpoint of storage stability.

Examples of the compound having an alcoholic hydroxyl group include monohydric alcohols such as methanol, ethanol, propanol, isopropanol, 1-butanol, 2-ethyl-1-hexanol and cyclohexanol; Dihydric alcohols such as ethylene glycol, propylene glycol, butane-1, 4-diol, diethylene glycol, triethylene glycol and tetraethylene glycol; Trihydric or higher polyhydric alcohols such as glycerin, pentaerythritol and the like can be used. A solvent having a functional group other than an alcoholic hydroxyl group in the molecule can also be used. Among them, those having two or more alcoholic hydroxyl groups in terms of miscibility with water and a vapor pressure are preferable, and dihydric alcohol and trihydric alcohol are more preferable, and ethylene glycol, propylene glycol and diethylene glycol are particularly preferable.

These compounds having an alcoholic hydroxyl group and / or a phenolic hydroxyl group may further contain other functional groups in the molecule. For example, a solvent having an alkoxy group together with an alcoholic hydroxyl group such as methyl cellosolve or cellosolve can also be used.

As the aprotic organic solvent, any one of a polar solvent and a non-polar solvent may be used.

Examples of the polar solvent include, but are not limited to, cyclic carboxylic acid esters such as? -Butyrolactone,? -Valerolactone and? -Valerolactone; Chain carboxylic acid esters such as methyl acetate, ethyl acetate and methyl propionate; Cyclic carbonate esters such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate; Examples of the solvent include chain type carbonate esters such as dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate, aliphatic amines such as N-methylformamide, N-ethylformamide, N, N-dimethylformamide, Amides such as amide, N, N-dimethylacetamide and N-methylpyrrolidone, nitriles such as acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile and 3-methoxypropionitrile; And phosphate esters such as trimethyl phosphate and triethyl phosphate.

The nonpolar solvent is not particularly limited, and examples thereof include hexane, toluene, and silicone oil.

These solvents may be used singly or in combination of two or more kinds. Particularly preferable as the non-aqueous solvent of the chemical liquid used for forming the anodic oxide film is ethylene glycol, propylene glycol, or diethylene glycol, either singly or in combination. In addition, if a non-aqueous solvent is contained, water may be contained.

The non-aqueous solvent is contained in an amount of usually not less than 10% by mass, preferably not less than 30% by mass, more preferably not less than 50% by mass, particularly preferably not less than 55% by mass, Preferably 90% by mass or less, particularly preferably 85% by mass or less.

When the chemical liquid includes water in addition to the nonaqueous solvent, the content thereof is usually 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, , Particularly preferably not less than 15 mass%, and the upper limit value is usually not more than 85 mass%, preferably not more than 50 mass%, particularly preferably not more than 40 mass%.

The ratio of water to the nonaqueous solvent is preferably 1% by mass or more, preferably 5% by mass or more, further preferably 7% by mass or more, particularly preferably 10% by mass or more, , And the upper limit is usually 90 mass% or less, preferably 60 mass% or less, more preferably 50 mass% or less, particularly preferably 40 mass% or less.

The chemical liquid may contain other additives as required. For example, an additive for improving the film forming property and the film property of the anodic oxide film may be contained. The additive is not particularly limited, and one or more kinds of materials selected from additives used in known chemical liquids and other materials may be added and used. At this time, there is no particular restriction on the amount of the additive to be added, and it may be an appropriate amount considering the effect and cost.

The electrolytic process for the anodic oxidation is not particularly limited. As the current waveform, for example, a pulse method in which an applied voltage is periodically interrupted, a PR method in which polarity is reversed, a modulation current such as other alternating current or alternating current direct current superimposition, incomplete rectification, triangular wave, Preferably, a direct current is used.

The method of controlling the current and voltage of the anodic oxidation is not particularly limited, and the conditions under which the oxide film is formed on the inner surface of the aluminum alloy container main body 1 can be appropriately combined. Normally, anodic oxidation treatment is preferably performed with a constant current and a constant voltage. In other words, it is preferable to perform conversion to a constant current up to a predetermined ignition voltage Vf, and to carry out anodic oxidation after reaching the ignition voltage for a predetermined time.

At this time, in order to form efficiently the oxide film, the current density is typically in the 0.001mA / cm ² or more, and in preferably, 0.01mA / cm ² or more. However, in order to obtain an oxide film having a good surface flatness, the current density is usually 100 mA / cm ² or less, preferably 10 mA / cm ² or less.

The harmonic voltage Vf is usually set to 3 V or more, preferably 10 V or more, and more preferably 20 V or more. Since the obtained oxide film thickness is related to the ignition voltage Vf, it is preferable to apply the above voltage or more in order to give a constant thickness to the oxide film. However, it is usually 1000 V or less, preferably 700 V or less, and more preferably 500 V or less. Since the obtained oxide film has high insulation property, it is preferable that the oxide film is formed under the above voltage in order to form a good quality oxide film without causing high insulation breakdown.

Alternatively, a method may be used in which an alternating current having a constant peak current value is used instead of the direct current power until reaching the harmonic voltage, and the voltage is changed to the direct voltage at the point where the harmonic voltage is reached and held for a predetermined time.

Other conditions of the anodic oxidation are not particularly limited. However, the temperature at the time of the anodic oxidation is within the temperature range in which the chemical liquid stably exists as a liquid. It is usually -20 占 폚 or higher, preferably 5 占 폚 or higher, and more preferably 10 占 폚 or higher. In view of production and energy efficiency at the time of anodic oxidation, it is preferable to carry out treatment at the above temperature or higher. However, it is usually 150 占 폚 or lower, preferably 100 占 폚 or lower, and more preferably 80 占 폚 or lower. In order to maintain the composition of the chemical liquid and perform uniform anodic oxidation, it is preferable to carry out the treatment at the temperature or lower.

Wherein the anodic oxidation includes a first step of disposing a predetermined surface of the aluminum alloy shaft seal mechanism component and an opposite electrode (for example, platinum) in the chemical solution, A second step of applying a constant current to the electrode for a predetermined time by applying a negative voltage to the electrode and a second step of applying a constant voltage between the aluminum alloy shaft seal mechanism constituent member and the electrode for a predetermined time 3 < / RTI > The predetermined period of time in the second step is a period of time until the voltage between the aluminum alloy shaft seal mechanism component and the predetermined electrode reaches a predetermined value (for example, when ethylene glycol is used, ) Is preferable.

It is preferable that the predetermined period of time in the third step is preferably performed until the current between the aluminum alloy shaft seal mechanism component and the predetermined electrode reaches a predetermined value. The current value decreases sharply after the voltage becomes the above-mentioned predetermined value and gradually decreases with time (hereinafter referred to as " residual current "), but in order to be equal to or smaller than the predetermined current value at the end of the constant- , It takes 24 hours. However, the film quality of the obtained Al ₂ O ₃ anodic oxide film is equivalent to that obtained by heat treatment. Further, the smaller the residual current, the better the film quality of the Al ₂ O ₃ anodized film. Taking these into consideration, in order to increase the productivity, it is preferable to stop the constant-voltage treatment at an appropriate time, and conduct heat treatment (annealing) in the next step. The heat treatment is preferably performed at 150 占 폚 or higher, and more preferably at about 300 占 폚 for 0.5 to 1 hour. However, if the remaining time of the residual current is not so long, the constant-voltage treatment may be continuously performed, and if it is long, the heat treatment may be performed.

In the second step, a current of 0.01 to 100 mA, preferably 0.1 to 10 mA, more preferably 0.5 to 2 mA is flowed per square cm, usually.

As mentioned above, in the third step, the voltage is a voltage at which the chemical liquid does not cause electrolysis.

Although not limited to any theory, from the knowledge obtained by the inventors of the present invention, the non-porous Al ₂ O ₃ anodic oxide film formed at the conversion treatment has an amorphous structure as a whole film, do. Further, by adding a compound having a more buffering effect or using a non-aqueous solvent as a solvent, a slight amount of carbon components are received in the anodic oxide film, and the bonding strength of Al-O is weakened, It is presumed that it is stabilized.

The Al ₂ O ₃ anodic oxide film produced as described above is preferably subjected to a heat treatment for the purpose of completely removing moisture in the film. Particularly, an Al anodic oxide film formed on an aluminum alloy base material containing high purity aluminum as a main component and containing substantially no such specific elements has high thermal stability and difficulty in forming voids and gas pools . Therefore, even if the annealing process is performed at a temperature of about 300 ° C or higher, almost no seam appears in the anodic oxide film of Al, so that the elution of aluminum into the reaction liquid due to the generation of particles and the exposure of aluminum can be suppressed .

The temperature of the heat treatment is not particularly limited, but is usually 100 ° C or higher, preferably 200 ° C or higher, and more preferably 250 ° C or higher. In order to sufficiently remove moisture on the surface and inside of the Al ₂ O ₃ anodic oxide film by the heat treatment, it is preferable to treat the film at a temperature equal to or higher than the above-mentioned temperature. However, it is usually 600 ° C or lower, preferably 550 ° C or lower, and more preferably 500 ° C or lower. It is preferable to treat at the above-mentioned temperature in order to maintain the amorphous structure of the Al ₂ O ₃ anodic oxide film and to maintain the flatness of the surface.

The time for the heat treatment is not particularly limited, but may be appropriately set in consideration of the surface roughness and the productivity due to heat treatment, but is usually 1 minute or longer, preferably 5 minutes or longer, particularly preferably 15 minutes Or more. In order to sufficiently remove moisture on the surface and inside of the Al ₂ O ₃ anodic oxide film, it is preferable to perform the treatment at the above-mentioned time or more. However, it is usually 180 minutes or less, preferably 120 minutes or less, and more preferably 60 minutes. In order to maintain the Al ₂ O ₃ anodic oxide film structure and surface flatness, it is preferable to perform the treatment within the above-mentioned time.

The in-furnace gas atmosphere at the time of the annealing is not particularly limited, but usually nitrogen, oxygen or a mixed gas thereof can be suitably used. Among them, an oxygen concentration of 18 vol% or more is preferable, a condition of 20 vol% or more is more preferable, and an oxygen concentration of 100 vol% is most preferable.

It is preferable that a primer treatment of PFA is performed on the backing surface on which the PFA film is directly provided when the PFA film is provided in order to improve the adhesion with the base surface.

In the present invention, the thickness of the undercoat film is preferably in the range of the smoothness of the PFA film-attached surface of the base material, the average particle size of the PFA powder used, or the PFA dispersed in the PFA paint so that the smoothness of the surface on which the PFA film is provided can be adequately secured as desired. The average particle size of the particles, and the like.

In the present invention, it is preferably 0.1 to 30 占 퐉, more preferably 1 to 20 占 퐉, still more preferably 2 to 15 占 퐉.

In order to provide the PFA film on the PFA film mounting surface or the base film surface (both of them are referred to as " PFA film forming surface ") of the member to be processed, they are also described in Experiments 1 and 2 and Examples described later. .

The PFA prepared to form the PFA film may be in the form of a fine powder for electrostatic charging, or a liquid such as a general paint. In the present invention, even if there is a somewhat complicated uneven shape in the shape of the member to be processed, it is preferable to use a fine powder for electrostatic chucking because it is easy to coat with a uniform thickness.

As for the coating method, it is preferable that the coating is performed by spray coating in the case of a liquid coating material such as a general coating material. However, depending on the base material, it may be coated by dip coating, dip spin coating, roll coating, Processing is also suitably employed. The powder coating material is preferably coated by electrostatic powder coating or electrostatic flow dipping.

Then, the PFA paint painted in this way is baked on the PFA film-formed surface of the member to be processed, but at that time, a process of melting and re-melting is given, and finally a PFA coating film having a desired smoothing performance is obtained.

The method of processing the coated film on the PFA film-formed surface of the member to be processed varies depending on the kind of the base material, the application, and the kind of the selected coating material, but it is preferable to carry out the processing described below.

(2) degreasing or color baking (3) roughening treatment (blast treatment) and / or base film formation (4) cleaning (1) preparation of metal base material (painted material) 5) primer coating → (6) preliminary drying → (7) top coat (PFA) coating → (8) preliminary drying → (9) primary firing (melting) → (10) (11) Second firing (re-melting) (12) When a topcoat layer having a second cooling (room temperature) thickness is provided, (8) Preliminary drying → (9) First firing (melting) "is repeated to form a topcoat layer having a desired thickness. In this case, the coating thickness per one time is appropriately determined depending on the type of the PFA to be used (powder or coating), the viscosity at the time of the melting treatment, the dispersion concentration and the particle diameter of the PFA in the case of the paint and the particle diameter of the powder in the case of the powder .

In the case of the present invention, the coating thickness per coating is preferably 1 to 100 mu m.

In the case of a plurality of coatings, the first firing temperature in the first coating is set as the intermediate first firing temperature, and the first firing temperature in the last coating is set as the final first firing temperature.

Although the intermediate primary sintering temperature and the final primary sintering temperature are set to the same temperature depending on the kind of PFA and the number of coatings, preferably, the intermediate primary sintering temperature is higher than the final primary sintering temperature Is set to be low.

(3), (5), and (6) are omitted in some cases. For example, even if the topcoat is directly provided on the surface of the member to be processed, the processing of (3), (5), and (6) is omitted if there is sufficient adhesive force between the surface of the member to be processed and the topcoat surface If the primer is firmly adhered to the base material and the top coat by performing the primer coating, the processing of (3) can be omitted.

The temperature and the time of the first firing in the present invention are determined by measuring the amount of impurities contained in the PFA material (which can be obtained in a powder form or a paint form) by the first firing (a low molecular weight component, A component having an end group, a product in a synthesis step, and an additive such as a surfactant, etc.) to the outside of the membrane. The upper limit of the temperature for the first firing is a temperature (referred to as " PFA decomposition temperature ") at which the PFA having a molecular weight necessary for constituting the PFA film giving a high level of smoothness ) Is preferable. Th is determined in relation to the holding time of the PFA coating film at that temperature in the first firing.

Th in the present invention is preferably set to 30 to 70 DEG C higher than the melting point of the PFA to be used. If the set temperature is too low, sufficient smoothness may not be obtained in the secondary firing, and if it is excessively high, decomposition of PFA may be promoted. More preferably 35 to 60 占 폚, and still more preferably 40 to 50 占 폚.

The first firing time in the present invention is a time for raising the temperature to the first firing temperature (first firing temperature rise time) and a time for maintaining the first firing temperature (first firing temperature holding time). In the first firing temperature rise time, the temperature rise speed is controlled by the control device so that the entire heat is transmitted to any portion of the PFA paint film so that the PFA paint film is uniformly fired. The first firing temperature holding time is a time to ensure that the entire free surface of the PFA paint film is uniformly melted so that the nonuniformity of the position is not visually deteriorated.

In the present invention, the first firing temperature holding time depends on the thickness and the size of the PFA coating film, and therefore, it is appropriately determined depending on the thickness and size of the PFA coating film, but preferably 10 to 50 minutes , It is preferable to set it to 15 to 40 minutes.

Since the smoothness of the film obtained after the second firing is determined according to the setting of the heating speed at the firing temperature and the firing temperature and the holding time at the firing temperature in the first firing, The holding time at the heating temperature and the firing temperature to the firing temperature is appropriately determined in consideration of the thickness and the size of the base material, the PAF, and the PFA paint film.

In the first firing, the impurities contained in the PFA material (which can be obtained in powder form or in the form of a paint) (an intermediate formed in the course of polymerisation, an unreacted or unreacted material, Material, etc.) is decomposed and removed from the PFA film. Unnecessary impurities are excluded from the PFA film in the first firing, so that the smoothness of the PFA film subjected to the second firing is improved. In addition, it is considered that the first firing is not only removal of impurities but also leveling (bonding state of molten particles) that affects smoothing in secondary firing.

It has been experimentally confirmed that if the first firing according to the present invention is omitted, this leveling is not appropriately performed and a desired smoothness can not be obtained.

In the present invention, the first firing is performed in a gas atmosphere in which rare gas is mixed with oxygen, such as ₂₀ vol% O ₂ / Ar gas atmosphere.

The atmospheric gas for the first firing is preferably a rare gas-oxygen mixed gas, but the present invention is not limited to this, and may be an oxygen gas alone or a nitrogen-oxygen mixed gas.

At the completion of the first firing, the sample is cooled to a temperature lower than the melting point of the PFA to be used (referred to as " Tl ") and solidified (primary cooling and solidification). The temperature Tl below the melting point is preferably lower than the melting point of the PFA to be used by preferably 5 to 60 占 폚, more preferably 10 to 50 占 폚, still more preferably 20 to 50 占 폚 Do. When the melting point has a width due to the molecular weight distribution of PFA, the mixing of a plurality of PFA having different molecular weights, etc., the first firing temperature is suitably selected within the above-mentioned range with respect to the lowest temperature in the temperature range of the width .

If the width of the temperature lower than the melting point of PFA is too small, smooth solidification can not be expected. If it is too large, the time required for re-melting is too much, and the production efficiency lowers.

The holding time at the temperature elevation speed and the second firing temperature for raising the temperature from the above-mentioned temperature (primary cooling / solidification temperature) Tl to the second firing temperature is secondly cooled to room temperature, and the smoothness of the free surface of the obtained PFA film It is set to be sufficiently secured.

The second firing temperature is a temperature for remelting the first solidified PFA film through the first firing process and the smoothing at the time of solidification after the first firing paint film is cooled down to room temperature to be performed next It is the promoting temperature.

The secondary firing is preferably carried out at a melting point of the PFA to be used or at a temperature higher than the melting point by 15 ° C or less. It is more preferable that the temperature is set at a temperature slightly different from the melting point of the PFA to be used or the melting point before and after the melting point.

Next, an example of a process of melting and remelting will be described below. When the Rf in the structural formula 1 is "-CF ₂ CF ₂ CF ₃ " (melting point is 310 ° C.), for example, the PFA fine powder on the PFA film formation side of the member to be processed is electrostatically coated to a predetermined thickness , Heated to 345 DEG C at a programmed heating rate, and maintained at 345 DEG C for 30 minutes (melting step). This melting process is performed in an atmosphere of ₂₀ vol% O ₂ / Ar gas. Subsequently, the atmosphere is changed to an argon atmosphere of 100 vol%, the temperature is lowered to 280 deg. C at a predetermined rate, and when the temperature is 280 deg. C, the temperature is maintained for 30 min. Subsequently, it is heated again to a temperature of 310 DEG C at a predetermined speed (a remelting step), and this temperature is maintained for 30 minutes. After holding for 30 minutes, the heating is stopped, and the temperature is allowed to fall to room temperature by allowing it to stand still. By this process, a PFA film having a very smooth free surface can be formed.

When Rf is PFA of "-CF ₂ CF ₂ CF ₃ ", the melting point is said to be 310 ° C., but the melting is already started between 295 ° C. and 305 ° C. Therefore, as the temperature of the remelting process, a temperature in the range of 295 DEG C to 315 DEG C can be selected. Preferably, a temperature in the range of 305 ° C to 315 ° C is selected.

The temperature at which the smoothness is most favorable is a temperature slightly differing from the melting point of 310 ° C or around, but in order to obtain a smoothness suitable for the purpose of the present invention, it is preferable to remelted at a temperature in the range of 305 ° C to 315 ° C desirable.

In the above description, the main pump of the present invention is a screw pump. However, the present invention is not limited to this screw pump, but is a type that supplies lubricating oil to the rotating mechanism. The present invention can be applied as long as it is a pump that prevents the steam from entering by using seal gas.

Experiment 1: Experiment and Smoothness Measurement of PFA Melting and Re-melting

After mirror-polishing process, subjected to a predetermined washing treatment of the SUS board-shaped base material: 2 a ^{(SUS316L-EP 10 × lOmm 2} , thickness 2mm) (base material 1 and 2), were prepared. The surface smoothness of the mirror-finished surface of these base materials was measured with a commercially available surface roughness tester (dektak 6M, Veeco Co.), and the surface roughness Ra was 0.006 占 퐉.

On one surface (base material 1) of the surface of which the surface smoothness was measured, a Ni film (thickness: 2 m) was formed by electroless plating. Conditions for electroless plating are described below.

Electroless plating solution (A): Nickel sulfate 26.3 g / l

Sodium hypophosphite · · · · · · 21.2 g / l

Citric acid ················· 25.0 g / l

Acetic acid 12.5 g / l

Rochelle salt · · · · · · · · · · 16.0 g / l

Element · · · · · · · · · · 12.5 g / l

pH ··········· 6.0

Bathing · · · · · · · · · · · 80 ℃

The mirror-finished surface of the base material 1 was subjected to the following treatment, and then immersed in the bath of the electroless plating solution (A) to form an Ni film.

Base material 1 was immersed in a commercially available degreasing agent (OPC-370 Condiclean M (trademark), manufactured by Okuno Pharmaceutical Co., Ltd.) at 60 ° C for 5 minutes. Then, the mirror-finished surface was sufficiently cleaned with ultrapure water for semiconductors by pulling up from the degreasing agent. Thereafter, it was immersed in a commercially available catalyst-imparting agent (OPC-80 Catalyst (trademark), manufactured by Okuno Pharmaceutical Co., Ltd.) at 25 ° C for 5 minutes. Then, the mirror-finished surface was sufficiently cleaned with ultra-pure water for semiconductors by being pulled up from the catalyst-imparting agent. After this washing, it was immersed in a commercially available activated solution (OPC-505 Accelerator (trademark), manufactured by Okuno Pharmaceutical Co., Ltd.) at 35 ° C for 5 minutes. Then, the mirror-finished surface was sufficiently cleaned with ultrapure water for semiconductor by lifting it from the activation liquid.

The base material 1 thus treated was immersed in the electroless plating solution (A) for 70 minutes. Subsequently, it was pulled up from the electroless plating solution (A) and sufficiently washed with ultra-pure water for semiconductor. Observed at night, the Ni film was uniformly formed on the entire mirror-finished surface, and the free surface was very smooth when touched with a finger.

The smoothness of the free surface of the Ni film was measured by the above-mentioned commercially available apparatus, and Ra was 0.006 탆 and the surface was not changed to the mirror-finished surface of the base material.

As described above, the base material 1 and the base material 2 provided with the Ni film were immersed in a commercially available degreasing agent (0PC-370 Condiclean M (trademark), manufactured by Okuno Pharmaceutical Co., Ltd.) at 60 ° C for 5 minutes to perform degreasing treatment did. Then, it was pulled up from the degreasing agent and sufficiently washed with ultra-pure water for semiconductors.

A precoat material (primer) was applied to the surface (the free surface of the Ni film) of the base material 1 subjected to such treatment and the surface (mirror-finished surface) on which the smoothness of the base material 2 was measured under the following conditions And dried.

Precoat material (primer): EK-1908S21L (manufactured by Daikin Industries, Ltd.)

Coating condition: Nozzle diameter of spray gun: 1.2mmφ

Fogging pressure ...... 0.3 MPa

Drying conditions: 85 占 폚, 15 minutes

Subsequently, a film of PFA powder was deposited to a thickness of 20 mu m by electrostatic coating on the pretreatment-treated surface of the base materials 1 and 2 under the following conditions, and then the base material was placed in a quartz (Quartz vessel).

Topcoat material: AC-5600 (manufactured by Daikin Industries, Ltd.)

Electrostatic painting device (manufactured by Ransburg Co., Ltd.): Hand gun --- REA 90 / L

High pressure controller ... 9040

The number of overlapping application · · · 3 times

Coating amount per one time ... 120 ± 10㎛

Intermediate firing between paints ··································· 340

In the infrared heating furnace used in this experiment, 100% argon was always flown at a flow rate of 1 l / min to the inside of the quartz container even when it was not used to maintain the cleanliness of the inside.

The infrared ray heating furnace has a configuration in which a thermocouple is attached to the outer periphery of a quartz container and the output of the infrared light source is controlled by a warmer so as to be at a programmed temperature based on temperature information from the thermocouple.

In the quartz container, a gas pipe for introducing gas from the outside is provided. For example, a gas such as argon mixed with 100 vol% argon and 20 vol% oxygen is introduced into the furnace to adjust the inside of the furnace to a desired atmosphere .

The two basic materials 1 and 2 coated with PFA were placed in a quartz container, and the opening and closing doors were closed to shut off the atmosphere, and 20 vol% O ₂ / Ar gas was supplied into the infrared heating furnace at a flow rate of 1 l / min . This state was maintained to wait for the atmosphere temperature in the space near the quartz container installation and the temperature of the quartz container to become constant. After the temperature was fixed, the infrared light source was turned on. The temperature of the quartz vessel just before the infrared light source ON was 25 占 폚. Subsequently, the output of the infrared light source was gradually increased, and the temperature was elevated linearly from 1 hour to 345 ° C. Subsequently, the state at 345 DEG C was maintained for 30 minutes. Thereafter, the gas was changed to Ar1OOvoL% gas, and this gas was flowed at a flow rate of 5 l / min for 10 minutes to set the temperature of the quartz container to 280 deg. I kept this state for 30 minutes. When the PFA treated surfaces of the basic materials 1 and 2 were visually observed, unevenness of the surface was observed. After maintaining the temperature for 30 minutes, the flow rate of Ar1OOvoL% gas was set to 1 l / min and the temperature was raised from 280 deg. C to 310 deg. C for 6 minutes. At the stage where the temperature became 310 ° C, the output of the infrared light source was controlled and the state was maintained for 30 minutes. Thereafter, the quartz container was taken out to the outside, and the base materials 1 and 2 were housed in a desiccator and naturally cooled.

When the PFA-treated surface of the base materials 1 and 2 at this time was visually observed, it was close to the mirror surface.

After the base materials 1 and 2 were sufficiently cooled naturally until the temperature reached room temperature, they were set in the surface roughness measuring apparatus and the smoothness of the PFA surface was measured. Hereinafter, for convenience, the PFA film on the base material 1 is referred to as a sample 1-1 and the PFA film on the base material 2 is referred to as a sample 1-2. The measurement was carried out by dividing the free surface of the PFA film of each material into 5 segments parallel to one side every 2 cm (for convenience, referred to as the X axis direction), and each divided surface was measured linearly from the end to the end of the sample. Then, the smoothness of the perpendicular direction (for convenience, referred to as the Y axis direction) to the above straight line was also measured in each of the divided areas by dividing the free surface of the PFA film of each material into 2 cm intervals (see FIG. 3).

The measurement results are shown in Table 1.

[Table 1]

Experiment 2

Each base material was subjected to Ni treatment and PFA treatment in the same manner as in Experiment 1 except that the planar base material in Experiment 1 was replaced with a semi-cylindrical base material having a cylindrical concave surface (radius of curvature: 5 cm) To thereby obtain a sample 2-1 (subjected to Ni treatment) and 2-2 (no Ni treatment) for smoothness measurement. The smoothness was measured in the same manner as in Experiment 1 with respect to these. The results are shown in Tables 2-1 and 2-2.

[Table 2-1 (Sample 2-1)]

[Table 2-2 (Sample 2-2)]

Experiment 3  : PFA Experiments on the re-melting of membranes and measurement of smoothness

Two sheets (Samples 3-1 and 3-2) of a planar SUS substrate (SUS316L-EP: 2 cm x 5 cm) having a mirror-polished surface were prepared and an Ni film was provided on the polished surface of the SUS substrate in the same manner as in Experiment 1 did. As in Experiment 1, the surface roughness of the mirror polished surface and the Ni film surface of the two SUS substrates were measured, and the same results as those of Experiment 1 were obtained.

PFA was coated on the Ni film of the SUS substrate provided with the Ni film on the surfaces of the two sheets according to the specifications by external commissioning.

Contractor: Japan Fluorine Industry Co., Ltd.

Topcoat material: ACX-31 (manufactured by Daikin Industries, Ltd.)

Painting: electrostatic painting

PFA paint thickness: 20㎛

Subsequently, the two SUS substrates coated with PFA were subjected to sintering treatment in the following steps. The furnace used was the same furnace as used in Experiment 1.

Two samples were placed in a quartz container provided with a SUS substrate to which PFA powder was electrostatically coated on a quartz glass tube, and firing was carried out in the following procedure.

(1) 20% 0 ₂ / Ar is flowed at a flow rate of 1 l / min and the temperature is raised from room temperature to 345 ° C for 1 hour.

(2) Keep the atmosphere at 345 캜 for 30 minutes.

(3) Ar 100% is flowed at a flow rate of 5 l / min and then lowered to 280 캜 for 10 minutes. In this step, the sample 3-2 is moved to the non-heated position so as to prevent the subsequent heating history (re-melting) from occurring.

(4) The atmosphere is kept at 280 占 폚 for 30 minutes.

(5) The atmosphere is changed to a flow rate of 1 l / min of Ar of 100%, and the temperature is raised from 280 DEG C to 310 DEG C in 6 minutes.

(6) The atmosphere is maintained at 310 ° C for 30 minutes.

(7) The heating is turned off, and the quartz burs (sample 3-1) is moved to the non-heated position, and natural cooling is performed.

The temperature program is shown below.

[Table 3]

The smoothness of the free surface of the PFA film of the sample 3-1 (with the re-melting history) and the sample 3-2 (without the re-melting history) in which the PFA film was formed was measured in the same manner as in Experiment 1. As a result, Sample 3-1 had very good smoothness and no bending was observed at all.

Sample 3-1: Ra = 0.061 탆, PV = 0.302 탆

Sample 3-2: Ra = 0.354 占 퐉, PV = 2.141 占 퐉

Experiment 4: Variation experiment of PFA

The PFA film was provided on the polished surface of the planar SUS base material in the same manner as in Experiment 1 except that the topcoat material was changed and the conditions were set forth in Table 4. The smoothness of the surface of the PFA film was measured in the same manner as in Experiment 1. The results are shown in Table 4.

Top coat material

MP-310 (Mitsui & DuPont Fluoro Chemicals)

EM-500CL (Mitsui & DuPont Fluoro Chemicals)

EM-700CL (Mitsui & DuPont Fluoro Chemicals)

AW-5000L (Daikin Industries, Ltd.)

[Table 4]

Example

As the main pump, a diaphragm pump having a maximum exhaust speed of 20,000 l / min, an unequal lead and an inclination angle of a screw gas exhausting pump, and a sub pump with a maximum exhaust speed of 12 l / min was prepared. Of the gas exhaust system of the present invention. A vacuum processing chamber was connected to the upstream side of the main pump.

The main pump was provided with a common pump except that the width of the gap 117 was 40 mu m, 30 mu m, 20 mu m, and 10 mu m by replacing the rotating shaft with a predetermined one. A pump having a width of 20 mu m and 10 mu m in width of the gap 117 formed a predetermined thickness of the PFA film on the outer peripheral surface of the rotating shaft to secure a predetermined gap.

The seal gas was supplied to the seal gas supply path 114 at a predetermined amount (X 1 / min) while the exhaust speed of the sub-pump 202 was adjusted so that the pressure of the pressure gauge 203 became 500 torr. The amount (Y l / min) of seal gas flowing through the seal gas exhaust path 201 at that time was measured by the flow meter 205. The results are shown in Table 5. From the measurement results, it shows the value obtained by calculating the seal gas flow rate (ml / min) flowing on the screw side (the exhaust system space of the main pump) and the drive meter (sub pump side).

[Table 5]

The pump according to the present invention can significantly reduce the consumption of the seal gas, so that the gas treatment cost for reusing the gas used in the treatment process can be remarkably reduced. In addition, it can greatly contribute to the reuse of valuable and expensive gases such as Kr and Xe, and is employed as a high efficiency pump in a resource circulation type system.

100 · · · · screw pump (body pump)
101 ···· Female screw rotor
102 ... male screw rotor
103 .... Screw fixture
104 ·················································································
105:
106:
107 ···· Angular contact bearings
108 · · · Seal housing
109 .... Lubricant supply path
110 .... Base plate
111 .... lubricating oil
112 ... lubricating oil storage portion
113 ......... seal member
114 ... seal gas supply path
115 · · · · seal gas discharge path
116 ···· Bearing body
117 .... Gap
201 · · · seal gas exhaust path
202 ···· Diaphragm pump (sub-pump)
203 ···· Pressure gauge
204 .... Needle valve
205 ··· Flowmeter
206 ···· Pressure gauge
207 .... Oil trap
208:
209 ··· Plug
210 ································································
211 ......... outer surface of the rotary shaft
212 PFA film
213 ....
214 ..... Seal gas inlet
215 · · · seal gas supply port

Claims (6)

1. A gas exhaust pump system having a body pump and a sub-pump,
The main pump includes:
A screw rotor,
A rotating shaft which is formed integrally with the screw rotor or integrally formed with the screw rotor and which is rotatably engaged with rotation driving means for rotating the screw rotor,
A holding means for holding the rotating shaft rotatably,
A lubricating oil supply path having at one end a lubricating oil for lubricating the holding means,
A seal housing covering a periphery of a portion of the rotating shaft not held by the holding means with a predetermined gap from an outer peripheral surface of the rotating shaft;
A seal member which is bridged between the rotary shaft and the seal housing over the entire circumference of the rotary shaft to prevent the lubricating oil poured into the holding means from intruding into the exhaust system space of the main pump through the gap;
A seal gas supply passage having a supply port for supplying a seal gas to the gap,
And a seal gas exhaust passage having a seal gas intake port for exhausting a seal gas supplied to the gap from the gap to the outside of the main pump,
The sub-pump is a pump for reducing the pressure of the seal gas exhaust passage,
And a membrane of a perfluoroalkoxyalkane represented by the structural formula (1) is provided on at least one of the outer peripheral surface of the rotary shaft and the inner peripheral surface of the seal housing.

(Structural formula 1)
Rf: perfluoroalkyl group,
m and n are positive integers.
1. A gas exhaust pump system having a body pump and a sub-pump,
The main pump includes:
A rotor,
A rotary shaft which is mounted on the rotor or integrally formed with the rotor and which is rotatably engaged with rotation driving means for rotating the rotor,
A holding means for holding the rotating shaft rotatably,
A lubricating oil supply path having at one end a lubricating oil for lubricating the holding means,
A seal housing covering a periphery of a portion of the rotating shaft not held by the holding means with a predetermined gap from an outer peripheral surface of the rotating shaft;
A seal member which is bridged between the rotary shaft and the seal housing over the entire circumference of the rotary shaft to prevent the lubricating oil poured into the holding means from intruding into the exhaust system space of the main pump through the gap;
A seal gas supply passage having a supply port for supplying a seal gas to the gap,
And a seal gas exhaust passage having a seal gas intake port for exhausting a seal gas supplied to the gap from the gap to the outside of the main pump,
The sub-pump is a pump for reducing the pressure of the seal gas exhaust passage,
And a membrane of a perfluoroalkoxyalkane represented by the structural formula (1) is provided on at least one of the outer peripheral surface of the rotary shaft and the inner peripheral surface of the seal housing.

(Structural formula 1)
Rf: perfluoroalkyl group,
m and n are positive integers.
A gas exhaust method using a gas exhaust pump system having a body pump and a sub-pump,
Wherein the body pump is in connection with the process chamber so as to reduce the pressure within the process chamber to below atmospheric pressure,
A screw rotor,
A rotating shaft which is formed integrally with the screw rotor or integrally formed with the screw rotor and which is rotatably engaged with rotation driving means for rotating the screw rotor,
A holding means for holding the rotating shaft rotatably,
A lubricating oil supply path having at one end a lubricating oil for lubricating the holding means,
A seal housing covering a periphery of a portion of the rotating shaft not held by the holding means with a predetermined gap from an outer peripheral surface of the rotating shaft;
A seal member which is bridged between the rotary shaft and the seal housing over the entire circumference of the rotary shaft to prevent the lubricating oil poured into the holding means from intruding into the exhaust system space of the main pump through the gap;
A seal gas supply passage having a supply port for supplying a seal gas to the gap upstream of the seal member;
And a seal gas exhaust passage having a seal gas intake port for exhausting the seal gas supplied to the gap from the gap to the outside of the body pump on the downstream side of the seal member,
The sub-pump is in a connection relationship with the seal gas exhaust passage for reducing the seal gas exhaust passage,
A membrane of a perfluoroalkoxyalkane represented by the structural formula (1) is provided on at least one of the outer circumferential surface of the rotating shaft and the inner circumferential surface of the seal housing,
And a step of interlocking the exhaust operation of the main pump and the decompression operation of the sub pump when the gas exhaust pump system is operated.

(Structural formula 1)
Rf: perfluoroalkyl group,
m and n are positive integers.
A gas exhaust method using a gas exhaust pump system having a body pump and a sub-pump,
Wherein the body pump is in connection with the process chamber so as to reduce the pressure within the process chamber to below atmospheric pressure,
A rotor,
A rotary shaft which is mounted on the rotor or integrally formed with the rotor and which is rotatably engaged with rotation driving means for rotating the rotor,
A holding means for holding the rotating shaft rotatably,
A lubricating oil supply path having at one end a lubricating oil for lubricating the holding means,
A seal housing covering a periphery of a portion of the rotating shaft not held by the holding means with a predetermined gap from an outer peripheral surface of the rotating shaft;
A seal member which is bridged between the rotary shaft and the seal housing over the entire circumference of the rotary shaft to prevent the lubricating oil poured into the holding means from intruding into the exhaust system space of the main pump through the gap;
A seal gas supply passage having a supply port for supplying a seal gas to the gap upstream of the seal member;
And a seal gas exhaust passage having a seal gas intake port for exhausting the seal gas supplied to the gap from the gap to the outside of the body pump on the downstream side of the seal member,
The sub-pump is in a connection relationship with the seal gas exhaust passage for reducing the seal gas exhaust passage,
A membrane of a perfluoroalkoxyalkane represented by the structural formula (1) is provided on at least one of the outer circumferential surface of the rotating shaft and the inner circumferential surface of the seal housing,
And a step of interlocking the exhaust operation of the main pump and the decompression operation of the sub pump when the gas exhaust pump system is operated.

(Structural formula 1)
Rf: perfluoroalkyl group,
m and n are positive integers. delete delete

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