Flow control valve and method of manufacturing the flow control valve

Abstract

To provide a flow control valve in which cross-linked PTFE having excellent abrasion resistance and capable of reducing a dust-generating amount is used only on a contact portion between a valve body and a valve seat, and to provide a producing method of the flow control valve.SOLUTION: According to a flow control valve 1 of the invention, a flow path-side body 10 and a valve body 40 are made of fluorine-based resin composed of PFA or PTFE, and an annular or circular seal member 81 made of cross-linked PTFE is joined to a valve body-side abutting portion 40a having a valve seat 13 against which the valve body 40 abuts and to a valve seat-side abutting portion 13a of the valve seat 13 against which the valve body 40 abuts.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flow control valve used in cleaning and peeling steps in silicon wafer processing, which often uses highly corrosive chemicals such as strong acids and strong alkalis, and a method for manufacturing the flow control valve. [Background technology]

[0002] Cross-linked PTFE is a material that has the same corrosion resistance and cleanliness as PTFE and PFA, and also has excellent abrasion resistance. Crosslinked PTFE has excellent abrasion resistance because the carbon atoms in the carbon-carbon (C-fluorine) bonds broken by radiation are bonded to other molecules that have been similarly created to form carbon-carbon bonds. However, crosslinked PTFE has the characteristic of having low bending resistance. Bending resistance has the effect of reducing the amount of dust generated from the sealing area between the valve seat and the valve body. If bending resistance is low, dust will be generated from the diaphragm of the control valve. Generally, due to the productivity of semiconductor manufacturing, control valves are required to be compact and have low pressure loss. This leads to increased deformation of the diaphragm of the control valve, and if the material has low bending resistance, cracks will occur when the valve operates, which will result in the generation of dust. Naturally, cracks can cause the diaphragm to break, and because this shortens the product's lifespan, cross-linked PTFE was not used for poppet diaphragms in control valves, which require compact size and low pressure loss. Regarding the valve seat and body, the cross-linking reduces the fluidity, so it was not possible to manufacture sheet material that was 300 mm square, for example. Although round bars can be manufactured by ram extrusion, there is a size limit and the required size cannot be obtained, so this method was not adopted. Even if cross-linked PTFE was used for either the valve body or the valve seat, the cross-linked PTFE would abrade the mating PTFE or PFA, so there was no effect in reducing the amount of dust generated. Patent Document 1 discloses a technique that allows cross-linked PTFE and PFA to be integrally formed. Furthermore, Patent Document 2 describes that there is a demand to eliminate gaps between members and prevent liquid from accumulating. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 221877 [Patent Document 2] Japanese Patent Application Publication No. 2020-200840 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because the insert molding described in Patent Document 1 does not completely melt and bond the parts, the surfactant used in the parts cleaning process for liquid control valve manufacturing can penetrate into gaps in the parts, causing organic matter contained in the surfactant to leach out when used in semiconductor manufacturing. In recent years, such organic contamination has become a problem due to miniaturization.

[0005] Therefore, an object of the present invention is to provide a flow control valve and a method for manufacturing a flow control valve in which cross-linked PTFE, which has excellent wear resistance and can reduce the amount of dust generated, is used only in the contact area between the valve body and the valve seat. [Means for solving the problem]

[0006] The flow control valve of the present invention according to claim 1 has a flow path side body 10 and a drive side body 20, the flow path side body 10 has an inflow flow path 11 through which a controlled fluid flows in, an outflow flow path 12 through which the controlled fluid flows out, and a valve seat 13 located between the inflow flow path 11 and the outflow flow path 12 formed therein, the drive side body 20 has a piston cylindrical space 21 formed therein in which a piston 30 is disposed, a valve element 40 is disposed at one end of the piston 30, an opening 21X is formed at one end of the piston cylindrical space 21 at a position opposite the valve seat 13, and a diaphragm 60 is disposed at the opening 21X. The flow control valves (1, 2, 3, 4, 5, 6) have a piston cylindrical space (21) and the valve seat (13) separated by the diaphragm (60), and the valve element (40) is disposed on the valve seat (13) side of the diaphragm (60), and the flow path side body (10) and the valve element (40) are formed of a fluororesin made of PFA or PTFE, and annular or circular seal members (81, 82, 83, 84, 85) made of cross-linked PTFE are joined to valve element side contact portions (40a, 40b, 40c, 40d) where the valve element (40) contacts the valve seat (13), and to a valve seat side contact portion (13a) of the valve seat (13) where the valve element (40) contacts. The sealing members 81, 82, 83, 84, and 85 are configured by laminating a cross-linked PTFE sheet 80y on one side of a PFA film 80x, and the PFA film 80x is joined to the valve body side contact portions 40a, 40b, 40c, and 40d or the valve seat side contact portion 13a. It is characterized by: Claim 2 The present invention as described is Claim 1 In the flow control valve described above, an annular protrusion 83a is formed on the sealing members 81, 83 that are joined to either the valve body side contact portions 40a, 40b or the valve seat side contact portion 13a, and the annular protrusion 83a is formed by varying the thickness of the PFA film 80x, and the thickness of the cross-linked PTFE sheet 80y is constant. Claim 3 The present invention as described is Claim 1 or Claim 2 In the flow control valve described in , the valve body side abutment portion 40c is formed by an annular surface inclined in the radial direction, and the inner periphery of the annular surface is closer to the valve seat 13 than the outer periphery of the annular surface. Claim 4 The present invention as described is Claim 1 or Claim 2 In the flow control valve described above, the valve body side contact portion 40d is formed by a convex curved surface, and the center of the convex curved surface is closer to the valve seat 13 than the outer periphery of the convex curved surface. Claim 5 The method for manufacturing a flow control valve of the present invention is as follows: Claim 4 a joining step of joining the sealing members 81, 82, 83, 84, 85 to the valve body side contact portions 40a, 40b, 40c, 40d and the valve seat side contact portion 13a, in which the sealing members 81, 82, 83, 84, 85 are placed on the valve body side contact portions 40a, 40b, 40c, 40d or the valve seat side contact portion 13a, and a heating block 100 that is directly heated by resistance heating is pressed against the sealing members 81, 82, 83, 84, 85 from the side of the sealing members 81, 82, 83, 84, 85. Claim 6 The method for manufacturing the flow control valve of the present invention described above includes the steps of: Claim 1 or Claim 2 The method for manufacturing the flow control valve described in the above item 1 is characterized in that the sealing member molding process for molding the sealing members 81, 82, 83, 84, and 85 includes a diffusion bonding process for overlapping and diffusion bonding the PFA film 80x and the cross-linked PTFE sheet 80y, and a die-cutting process for die-cutting the laminated sheet of the PFA film 80x and the cross-linked PTFE sheet 80y diffusion-bonded in the diffusion bonding process into an annular or circular shape. Claim 7 The method for manufacturing the flow control valve of the present invention described above includes the steps of: Claim 2 10. The method for manufacturing the flow control valve according to claim 9, wherein the seal member molding step of molding the seal member 83 comprises: The method is characterized by comprising a diffusion bonding process in which the PFA film 80x and the cross-linked PTFE sheet 80y are stacked and diffusion bonded together, a molding process in which the laminated sheet of the PFA film 80x and the cross-linked PTFE sheet 80y diffusion bonded in the diffusion bonding process is heated and molded to form the annular protrusion 83a, and a die-cutting process in which the laminated sheet molded in the molding process is die-cut into an annular or circular shape. Claim 8 The present invention as described is Claim 6 or Claim 7 In the method for manufacturing a flow control valve described in 1. above, the cross-linked PTFE sheet 80y is formed by orthogonally cutting the outer peripheral surface of a columnar or cylindrical rod material 90. Claim 9 The present invention as described is Claim 6 or Claim 7 In the method for manufacturing a flow control valve described in 1. above, the cross-linked PTFE sheet 80y is formed by orthogonally cutting the end face of the rod material 90. Claim 10 The present invention is characterized in that, in the flow control valve described in claim 1, the sealing members 81, 82, 83, 84, 85 joined to either the valve body side abutment portions 40a, 40b, 40c, 40d or the valve seat side abutment portion 13a are made of cross-linked PFA instead of cross-linked PTFE. Claim 11 The present invention as described is Claim 5 In the method for manufacturing a flow control valve described above, in the joining step, the surfaces of the sealing members 81, 82, 83, 84, and 85 are flattened by the heating block 100. Claim 12 The present invention as described is Claim 5 In the method for manufacturing a flow control valve described in the above, in the bonding step, heating is stopped at a timing when the displacement amount per unit time of the heating block 100 becomes small. Claim 13 The present invention as described is Claim 5 In the method for manufacturing a flow control valve described in the above, in the joining step, heating is stopped at a timing when the displacement amount per unit time of the heating block 100 becomes negative. [Effects of the Invention]

[0007] According to the flow control valve of the present invention, an annular or circular sealing member made of cross-linked PTFE is joined to the valve body side abutment portion where the valve body abuts against the valve seat, and to the valve seat side abutment portion of the valve seat against which the valve body abuts. This allows the use of cross-linked PTFE, which has excellent abrasion resistance and can reduce the amount of dust generated, only at the contact portion between the valve body and the valve seat, and by using a fluororesin made of PFA or PTFE for the valve body and the valve seat, it is possible to obtain a joining strength that exceeds the strength of a frictional joint due to the entanglement of polymers. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a flow control valve according to a first embodiment of the present invention; [Figure 2] 1 is a cross-sectional view showing a flow control valve according to a second embodiment of the present invention; [Figure 3] 1 is an end view showing the configuration and manufacturing process of a circular seal member suitable for a flow control valve according to a first embodiment of the present invention; [Figure 4] 10 is a cross-sectional view showing a flow control valve according to a third embodiment of the present invention. [Figure 5] FIG. 10 is a cross-sectional view showing a flow control valve according to a fourth embodiment of the present invention. [Figure 6] 10A and 10B are end views showing the configuration and manufacturing process of an annular seal member suitable for the flow control valve according to the third and fourth embodiments of the present invention. [Figure 7] FIG. 10 is a cross-sectional view showing a flow control valve according to a fifth embodiment of the present invention. [Figure 8] FIG. 10 is a cross-sectional view showing a flow control valve according to a sixth embodiment of the present invention. [Figure 9] An image showing the method for forming the crosslinked PTFE sheet shown in Figures 2 and 6. [Figure 10] FIG. 1 is a diagram showing the configuration of an apparatus used in a joining step of joining a seal member to a valve body-side contact portion and a valve seat-side contact portion in a manufacturing method of a flow control valve of the present invention. [Figure 11] Figure 10 shows the surface roughness of the sealing material before and after the joining process. [Figure 12] A diagram showing the melting molding process shown in Figure 6(b). [Figure 13] Graph showing timing for ending heating in the bonding process shown in FIG. 10(a) [Figure 14] Graph showing the timing of ending heating in the bonding process shown in FIG. 10(b). DETAILED DESCRIPTION OF THE INVENTION

[0009] In the flow control valve according to the first embodiment of the present invention, the flow path side body and the valve element are formed of a fluororesin made of PFA or PTFE, and an annular or circular seal member made of cross-linked PTFE is joined to the valve element side contact portion where the valve element contacts the valve seat and to the valve seat side contact portion of the valve seat where the valve element contacts. The sealing member is configured by laminating a cross-linked PTFE sheet on one side of a PFA film, and the PFA film is joined to the valve body side contact portion or the valve seat side contact portion. are. According to this embodiment, by joining an annular or circular sealing member made of cross-linked PTFE to the valve body side contact portion where the valve body contacts the valve seat and the valve seat side contact portion of the valve seat against which the valve body contacts, cross-linked PTFE, which has excellent abrasion resistance and can reduce the amount of dust generated, can be used only at the contact portion between the valve body and the valve seat, and by using a fluororesin made of PFA or PTFE for the valve body and the valve seat, it is possible to obtain a joint strength that exceeds the strength of a friction joint due to the entanglement of polymers. Furthermore, by forming the sealing member into a thin sheet using a PFA film and a cross-linked PTFE sheet, variations in melt flow rate are less likely to occur, the shape can be maintained when welding and joining, and uniform joining strength can be obtained.

[0010] The present invention No. 2 The embodiment of the present invention is No. 1 In the flow control valve according to the embodiment, an annular protrusion is formed on the sealing member that is joined to either the valve body side contact portion or the valve seat side contact portion, and the annular protrusion is formed by varying the thickness of the PFA film, and the thickness of the cross-linked PTFE sheet is constant. According to this embodiment, by forming an annular protrusion on the sealing member, the contact area between the valve body and the valve seat can be reduced, thereby reducing the amount of dust generated. The cross-linked PTFE, which is difficult to shape, is made into a sheet of constant thickness, and the annular protrusion is formed by varying the thickness of the PFA film, making it easy to form the annular protrusion.

[0011] The present invention Third The first embodiment of the present invention is or second In the flow control valve according to the embodiment, the valve body side contact portion is formed by an annular surface inclined in the radial direction, and the inner periphery of the annular surface is closer to the valve seat than the outer periphery of the annular surface. According to this embodiment, by forming the valve element side contact portion by an annular surface, the contact area between the valve element and the valve seat can be reduced, thereby reducing the amount of dust generated.

[0012] The present invention FourthThe first embodiment of the present invention is or second In the flow control valve according to the embodiment, the valve body side contact portion is formed by a convex curved surface, and the center of the convex curved surface is closer to the valve seat than the outer periphery of the convex curved surface. According to this embodiment, by forming the valve element side contact portion with a convex curved surface, the contact area between the valve element and the valve seat can be reduced, thereby reducing the amount of dust generated.

[0013] The present invention No. 5 The embodiment of the present invention is 1st to 4th In the method for manufacturing a flow control valve according to any one of the above embodiments, in the joining process for joining the seal member to the valve body side abutment portion and the valve seat side abutment portion, the seal member is placed on the valve body side abutment portion or the valve seat side abutment portion, and a heating block that is directly heated by resistance heating is pressed against the seal member side. According to this embodiment, by directly heating the sealing member made of cross-linked PTFE with a heating block, the cross-linked PTFE is softened or semi-melted, and the contact interface with the sealing member of the valve body side abutting portion or valve seat side abutting portion made of PFA or PTFE is heated and melted by the heat from the sealing member, thereby achieving a strong bond. Furthermore, by using cross-linked PTFE as the sealing member and directly heating the heating block with resistance heating, temperature control at the contact interface can be easily performed, and temperature control with high responsiveness to the melting surface temperature can be achieved.

[0014] The present invention No. 6 The embodiment of the present invention is No. 1 or No. 2 In the method for manufacturing a flow control valve according to the embodiment, the sealing member molding process for molding the sealing member includes a diffusion bonding process for overlapping and diffusion bonding a PFA film and a crosslinked PTFE sheet, and a die-cutting process for die-cutting the laminated sheet of the PFA film and the crosslinked PTFE sheet diffusion-bonded in the diffusion bonding process into an annular or circular shape. According to this embodiment, the seal member can be formed using cross-linked PTFE, which is difficult to shape.

[0015] The present invention Seventh The embodiment of the present invention is No. 2 In the method for manufacturing a flow control valve according to the embodiment, the sealing member molding process for molding the sealing member includes a diffusion bonding process for overlapping and diffusion bonding a PFA film and a crosslinked PTFE sheet, a molding process for hot molding the laminated sheet of the PFA film and the crosslinked PTFE sheet diffusion bonded in the diffusion bonding process to form an annular protrusion, and a die-cutting process for die-cutting the laminated sheet molded in the molding process into an annular or circular shape. According to this embodiment, the annular protrusion can be formed on the seal member using crosslinked PTFE, which is difficult to shape.

[0016] The present invention No. 8 The embodiment of the present invention is No. 6 or Seventh In the method for manufacturing a flow control valve according to this embodiment, the crosslinked PTFE sheet is formed by orthogonally cutting the outer circumferential surface of a columnar or cylindrical rod material. According to this embodiment, a long crosslinked PTFE sheet of a predetermined width can be formed by orthogonally cutting the outer peripheral surface of a columnar or cylindrical rod material.

[0017] The present invention No. 9 The embodiment of the present invention is No. 6 or Seventh In the method for manufacturing a flow control valve according to this embodiment, the cross-linked PTFE sheet is formed by orthogonally cutting the end face of the rod material. According to this embodiment, by orthogonally cutting the end face of the rod material, a crosslinked PTFE sheet having the same size as the end face can be formed.

[0018] The present invention No. 10 In this embodiment, in the flow control valve according to the first embodiment, the seal member joined to either the valve body side contact portion or the valve seat side contact portion is made of cross-linked PFA instead of cross-linked PTFE. According to this embodiment, by joining an annular or circular sealing member made of cross-linked PFA to the valve body side contact portion where the valve body contacts the valve seat and the valve seat side contact portion of the valve seat against which the valve body contacts, cross-linked PFA, which has excellent abrasion resistance and can reduce the amount of dust generated, can be used only at the contact portion between the valve body and the valve seat, and by using a fluororesin made of PFA or PTFE for the valve body and the valve seat, it is possible to obtain a joint strength that exceeds the strength of a friction joint due to the entanglement of polymers.

[0019] The present invention No. 11 The embodiment of the present invention is No. 5 In the method for manufacturing a flow control valve according to the embodiment, the bonding step flattens the surface of the seal member by using a heating block. According to this embodiment, the surface of the sealing member can be flattened by pressing the heating block, which is directly heated by resistance heating, against the sealing member from the sealing member side.

[0020] The present invention No. 12 The embodiment of the present invention is No. 5 In the method for manufacturing a flow control valve according to the embodiment, in the joining step, heating is stopped at a timing when the displacement amount per unit time of the heating block becomes small. According to this embodiment, since the height of the seal member changes as the valve disc or valve seat thermally expands and melts, the timing for stopping heating of the heating block can be determined based on the amount of displacement of the heating block per unit time. Furthermore, if the volume of the valve disc or valve seat is large, thermal expansion continues even after welding of the seal member is complete. Therefore, by stopping heating at a timing when the amount of displacement of the heating block per unit time becomes small, the bonding state between the seal member and the valve disc-side abutting portion or the valve seat-side abutting portion can be controlled to a constant state.

[0021] The present invention 13 The embodiment of the present invention is No. 5 In the method for manufacturing a flow control valve according to the embodiment, in the joining step, heating is stopped at a timing when the displacement amount per unit time of the heating block becomes negative. According to this embodiment, since the height of the seal member changes as the valve disc or valve seat thermally expands and the seal member melts, the timing for stopping heating of the heating block can be determined based on the displacement of the heating block per unit time. Furthermore, when the volume of the valve disc or valve seat is small, the heating block moves upward due to the thermal expansion of the valve disc-side contact portion or the valve seat-side contact portion, and then the thermal expansion saturates and the seal member melts, causing the heating block to move downward. Therefore, by stopping heating when the displacement of the heating block per unit time becomes negative, the bonding state between the seal member and the valve disc-side contact portion or the valve seat-side contact portion can be controlled to be constant. [Example]

[0022] A flow control valve according to an embodiment of the present invention will now be described. FIG. 1 is a cross-sectional view showing a flow control valve according to a first embodiment of the present invention.

[0023] The flow control valve 1 according to this embodiment has a flow path side body 10 and a drive side body 20 . The flow path side body 10 has formed therein an inflow flow path 11 through which the controlled fluid flows in, an outflow flow path 12 through which the controlled fluid flows out, and a valve seat 13 located between the inflow flow path 11 and the outflow flow path 12. The driving side body 20 defines therein a cylindrical space 21 for a piston in which the piston 30 is disposed.

[0024] A valve body 40 is disposed at one end of the piston 30 . The end of the valve element 40 on the valve seat 13 side is a valve element side contact portion 40 a that contacts the valve seat 13 . The end of the valve seat 13 on the valve element 40 side is a valve seat-side contact portion 13a with which the valve element 40 comes into contact. In this embodiment, the valve element side contact portion 40a is formed of a circular flat surface, and the valve seat side contact portion 13a is formed of an annular flat surface. The piston cylindrical space 21 has a piston biasing means 50 that biases the piston 30. The piston biasing means 50 biases the piston 30 in a direction in which the valve body 40 abuts against the valve seat 13. The piston 30 is formed with a piston enlarged portion 31. The piston biasing means 50 biases the piston 30 by pressing the piston enlarged portion 31. The piston biasing means 50 may be, for example, a coil spring. An opening 21x is formed at one end of the cylindrical space 21 for the piston at a position facing the valve seat 13. A diaphragm 60 is disposed in this opening 21x, and the piston cylindrical space 21 and the valve seat 13 are separated by the diaphragm 60. The diaphragm 60 is held by the flow path side body 10 and a diaphragm holder 70. The diaphragm 60 may be held by the flow path side body 10 and the drive side body 20 without providing the diaphragm holder 70. Furthermore, in this embodiment, the diaphragm holder 70 has the function of supporting the piston 30, but the diaphragm holder 70 does not have to have the function of supporting the piston 30.

[0025] The diaphragm 60 is disposed on one end side of the piston 30. One end of the piston 30 is located at the center of the diaphragm 60, and the valve element 40 is disposed on the valve seat 13 side of the diaphragm 60. The diaphragm 60 is deformed as the piston 30 moves. The diaphragm 60 has a thick portion 61 connected to the piston 30, a membrane portion 62 formed on the outer periphery of the thick portion 61, and a fixed portion 63 formed on the outer periphery of the membrane portion 62. The diaphragm 60 is connected to the piston 30 at the center of the thick portion 61, and the membrane portion 62 is the main portion that deforms. In this embodiment, the valve body 40 and the diaphragm 60 are integrally formed from the same material, but the valve body 40 and the diaphragm 60 may be formed as separate members.

[0026] In the flow control valve 1 according to this embodiment, the flow path side body 10 and the valve element 40 are formed from a fluorine-based resin such as PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin) or PTFE (tetrafluoroethylene resin). Furthermore, annular or circular seal members 81, 82 made of cross-linked PTFE are joined to the valve body side contact portion 40a and the valve seat side contact portion 13a. In this embodiment, a circular sealing member 81 is joined to the valve body side abutment portion 40a, and an annular sealing member 82 is joined to the valve seat side abutment portion 13a, but the sealing member 81 joined to the valve body side abutment portion 40a may also be an annular sealing member 82.

[0027] Air flow passages 22 and 23 are formed in the driving-side body 20. The air flow passage 22 communicates with a piston cylindrical space 21a between the diaphragm 60 and the piston expansion portion 31, and the air flow passage 23 communicates with a piston cylindrical space 21b in which the piston biasing means 50 is disposed.

[0028] FIG. 1 shows the valve body 40 in a fully open state. By supplying gas from the air flow passage 22 to the piston cylindrical space 21a, pressure is applied to the piston 30 in a direction opposite to the biasing force of the piston biasing means 50. Therefore, the piston 30 moves in a direction that separates the valve body 40 from the valve seat 13. When the valve element 40 moves away from the valve seat 13, the controlled fluid flows in from the inflow passage 11, and the pressure of the controlled fluid is applied to the diaphragm 60. The gas in the piston cylindrical space 21b is discharged through the air flow passage . To change the valve element 40 from the fully open state to the closed state, gas in the piston cylindrical space 21a is discharged through the air flow passage 22. By discharging the gas from the piston cylindrical space 21a, the pressure in the piston cylindrical space 21a decreases, and the piston 30 is biased by the piston biasing means 50 to move in a direction approaching the valve seat 13. Gas is drawn into the piston cylindrical space 21b through the air flow passage 23. When the valve element 40 is in the closed state, the piston biasing means 50 biases the valve element 40 to abut against the valve seat 13, and the seal member 81 of the valve element abutment portion 40a and the seal member 82 of the valve seat abutment portion 13a come into contact with each other.

[0029] According to this embodiment, annular or circular sealing members 81, 82 made of cross-linked PTFE are joined to the valve body side contact portion 40a where the valve body 40 contacts the valve seat 13, and to the valve seat side contact portion 13a of the valve seat 13 where the valve body 40 contacts, so that cross-linked PTFE, which has excellent abrasion resistance and can reduce the amount of dust generated, can be used only at the contact portion between the valve body 40 and the valve seat 13, and by using a fluororesin made of PFA or PTFE for the valve body 40 and the valve seat 13, it is possible to obtain a joining strength that exceeds the strength of a frictional joint due to the entanglement of polymers.

[0030] 2 is a cross-sectional view showing a flow control valve according to a second embodiment of the present invention. The same components as those in the flow control valve according to the first embodiment are given the same reference numerals and their explanations will be omitted. In the flow control valve 2 according to this embodiment, a convex portion 41 that protrudes toward the valve seat 13 is formed in the center of the end portion of the valve element 40 on the valve seat 13 side, and a valve element side abutment portion 40b that abuts against the valve seat 13 is formed on the outer periphery of the convex portion 41. Therefore, the valve element side abutment portion 40b is formed as an annular flat surface. In this embodiment, an annular seal member 82 is joined to the valve body side contact portion 40b.

[0031] According to this embodiment, an annular sealing member 82 made of cross-linked PTFE is joined to the valve body side contact portion 40b where the valve body 40 contacts the valve seat 13, and to the valve seat side contact portion 13a of the valve seat 13 where the valve body 40 contacts. This allows the use of cross-linked PTFE, which has excellent abrasion resistance and can reduce the amount of dust generated, only at the contact portion between the valve body 40 and the valve seat 13, and by using a fluororesin made of PFA or PTFE for the valve body 40 and the valve seat 13, it is possible to obtain a joining strength that exceeds the strength of a frictional joint due to the entanglement of polymers.

[0032] 3A and 3B are end views showing the configuration and manufacturing process of a circular sealing member suitable for a flow control valve according to a first embodiment of the present invention, where FIG. 3A shows the diffusion bonding process and FIG. 3B shows the die-cutting process. The circular sealing member 81 is constructed by laminating a cross-linked PTFE sheet 80y on one surface of a PFA film 80x. The thickness of the PFA film 80x is preferably 0.3 mm to 0.6 mm, and the thickness of the cross-linked PTFE sheet 80y is preferably 0.05 mm to 0.6 mm. As shown in FIG. 3(a), a PFA film 80x and a cross-linked PTFE sheet 80y are laminated and diffusion bonded. Then, as shown in FIG. 3(b), a circular seal member 81 is formed by die cutting. The annular seal member 82 according to the first and second embodiments is die-cut into an annular shape in the die-cutting step shown in FIG. 3(b). The circular or annular seal members 81, 82 are joined to the valve body 40 or the valve seat 13 by welding the PFA film 80x to the valve body side contact portions 40a, 40b or the valve seat side contact portion 13a.

[0033] In this way, the sealing member molding process for forming the sealing members 81 and 82 includes a diffusion bonding process in which the PFA film 80x and the cross-linked PTFE sheet 80y are stacked and diffusion bonded together, and a die-cutting process in which the laminated sheet of the PFA film 80x and the cross-linked PTFE sheet 80y diffusion-bonded in the diffusion bonding process is die-cut into an annular or circular shape, thereby making it possible to form the sealing members 81 and 82 using cross-linked PTFE, which is difficult to shape. Furthermore, by constructing the circular or annular sealing members 81, 82 in the form of thin sheets using PFA film 80x and cross-linked PTFE sheet 80y, variations in melt flow rate are less likely to occur, the shape can be maintained while welding and joining, and uniform joining strength can be obtained.

[0034] 4 is a cross-sectional view showing a flow control valve according to a third embodiment of the present invention. The same components as those in the flow control valves according to the first and second embodiments are given the same reference numerals and their explanations will be omitted. In the flow control valve 3 according to this embodiment, an annular protrusion 83a is formed on the seal member 83 that is joined to the valve element side contact portion 40b. The valve element side contact portion 40b is formed as an annular flat surface on the outer periphery of the protrusion 41. The annular seal member 83 is joined to the valve element side contact portion 40b that is formed as an annular flat surface.

[0035] According to this embodiment, an annular sealing member 83 made of cross-linked PTFE is joined to the valve body side contact portion 40b where the valve body 40 contacts the valve seat 13, and an annular sealing member 82 made of cross-linked PTFE is joined to the valve seat side contact portion 13a of the valve seat 13 where the valve body 40 contacts. This makes it possible to use cross-linked PTFE, which has excellent abrasion resistance and can reduce the amount of dust generated, only at the contact portion between the valve body 40 and the valve seat 13, and by using a fluororesin made of PFA or PTFE for the valve body 40 and the valve seat 13, it is possible to obtain a joining strength that exceeds the strength of a frictional joint due to polymer entanglement. Furthermore, according to this embodiment, by forming the annular protrusion 83a on the annular seal member 83, the contact area between the valve body 40 and the valve seat 13 can be reduced, thereby reducing the amount of dust generated. The circular seal member 81 may be formed with an annular protrusion 83a.

[0036] 5 is a cross-sectional view showing a flow control valve according to a fourth embodiment of the present invention. The same components as those in the flow control valves according to the first to third embodiments are given the same reference numerals and their explanations will be omitted. In the flow control valve 4 according to this embodiment, an annular protrusion 83a is formed on the seal member 83 that is joined to the valve seat side contact portion 13a.

[0037] According to this embodiment, an annular sealing member 82 made of cross-linked PTFE is joined to the valve body side contact portion 40b where the valve body 40 contacts the valve seat 13, and an annular sealing member 83 made of cross-linked PTFE is joined to the valve seat side contact portion 13a of the valve seat 13 where the valve body 40 contacts.This makes it possible to use cross-linked PTFE, which has excellent wear resistance and can reduce the amount of dust generated, only at the contact portion between the valve body 40 and the valve seat 13, and by using a fluororesin made of PFA or PTFE for the valve body 40 and the valve seat 13, it is possible to obtain a joining strength that exceeds the strength of a frictional joint due to polymer entanglement. Furthermore, according to this embodiment, by forming the annular protrusion 83a on the annular seal member 83, the contact area between the valve body 40 and the valve seat 13 can be reduced, thereby reducing the amount of dust generated.

[0038] 6A and 6B are end views showing the configuration and manufacturing process of an annular sealing member suitable for the flow control valves according to the third and fourth embodiments of the present invention, in which FIG. 6A shows the diffusion bonding process, FIG. 6B shows the melt molding process, and FIG. 6C shows the die-cutting process. The annular sealing member 83 is constructed by laminating a cross-linked PTFE sheet 80y on one surface of a PFA film 80x. The thickness of the PFA film 80x is preferably 0.3 mm to 0.6 mm, and the thickness of the cross-linked PTFE sheet 80y is preferably 0.05 mm to 0.3 mm. As shown in FIG. 6(a), a PFA film 80x and a cross-linked PTFE sheet 80y are laminated and diffusion bonded. 6(b), the PFA film 80x is melted by resistance heating and shaped using a heating block. This shaping process varies the thickness of the PFA film 80x to form the annular protrusions 83a. By setting the heating temperature below the melting point of the cross-linked PTFE, the cross-linked PTFE sheet 80y deforms along the surface of the PFA film 80x while maintaining a constant thickness. Thereafter, as shown in FIG. 6(c), an annular sealing member 83 is formed by die cutting. The circular seal member 81 according to the first embodiment is die-cut into a circular shape in the die-cutting step shown in FIG. 3(b). The circular or annular seal members 81, 82 are joined to the valve body 40 or the valve seat 13 by welding the PFA film 80x to the valve body side contact portions 40a, 40b or the valve seat side contact portion 13a.

[0039] In this way, the sealing member molding process for molding the sealing member 83 includes a diffusion bonding process in which the PFA film 80x and the crosslinked PTFE sheet 80y are stacked and diffusion bonded together, a molding process in which the laminated sheet of the PFA film 80x and the crosslinked PTFE sheet 80y diffusion bonded in the diffusion bonding process is heated and molded to form the annular protrusion 83a, and a die-cutting process in which the laminated sheet molded in the molding process is cut into an annular or circular shape, thereby making it possible to form the annular protrusion 83a on the sealing member 83 using crosslinked PTFE, which is difficult to shape. Furthermore, by forming the sealing member 83 in the form of a thin sheet using the PFA film 80x and the cross-linked PTFE sheet 80y, variations in melt flow rate are less likely to occur, the shape can be maintained when welding and joining, and uniform joining strength can be obtained. Furthermore, the cross-linked PTFE, which is difficult to shape, is made into a sheet of a constant thickness, and the annular protrusion 83a is formed by varying the thickness of the PFA film 80x, thereby making it possible to easily form the annular protrusion 83a.

[0040] 7 is a cross-sectional view showing a flow control valve according to a fifth embodiment of the present invention. The same components as those in the flow control valves according to the first to fourth embodiments are given the same reference numerals and their explanations will be omitted. In the flow control valve 5 according to this embodiment, a convex portion 41 that protrudes toward the valve seat 13 is formed in the center of the end portion of the valve element 40 on the valve seat 13 side, and a valve element side abutment portion 40c that abuts against the valve seat 13 is formed on the outer periphery of the convex portion 41. The valve element side abutment portion 40c is formed by an annular surface that is inclined in the radial direction, and the inner periphery of the annular surface is closer to the valve seat 13 than the outer periphery of the annular surface. The annular seal member 84 is joined to the valve-disk-side contact portion 40c. The annular seal member 84 is preferably configured by laminating a cross-linked PTFE sheet 80y on one side of a PFA film 80x as shown in FIG. 3, and can be manufactured using the manufacturing process shown in FIG. 3. To form the annular seal member 84 into an annular surface that conforms to the valve-disk-side contact portion 40d, the PFA film 80x may be melted by resistance heating and molded in a mold as shown in FIG. 6(b). The annular seal member 84 is molded into an inclined annular surface with a constant thickness of the PFA film 80x.

[0041] According to this embodiment, an annular sealing member 84 made of cross-linked PTFE is joined to the valve body side contact portion 40c where the valve body 40 contacts the valve seat 13, and an annular sealing member 82 made of cross-linked PTFE is joined to the valve seat side contact portion 13a of the valve seat 13 where the valve body 40 contacts. This makes it possible to use cross-linked PTFE, which has excellent abrasion resistance and can reduce the amount of dust generated, only at the contact portion between the valve body 40 and the valve seat 13, and by using a fluororesin made of PFA or PTFE for the valve body 40 and the valve seat 13, it is possible to obtain a joint strength that exceeds the strength of a friction joint due to polymer entanglement. Furthermore, according to this embodiment, the valve element side contact portion 40c is formed by an annular surface, so that the contact area between the valve element 40 and the valve seat 13 can be reduced, thereby reducing the amount of dust generated.

[0042] 8 is a cross-sectional view showing a flow control valve according to a sixth embodiment of the present invention. The same components as those in the flow control valves according to the first to fifth embodiments are given the same reference numerals and their explanations will be omitted. In the flow control valve 6 according to this embodiment, the end of the valve body 40 on the valve seat 13 side is formed by a convex curved surface, and the center of the convex curved surface is closer to the valve seat 13 than the outer periphery of the convex curved surface to form the valve body side abutment portion 40d. The circular seal member 85 is joined to the valve-disk-side contact portion 40d. The circular seal member 85 is preferably configured by laminating a cross-linked PTFE sheet 80y on one side of a PFA film 80x as shown in FIG. 3, and can be manufactured using the manufacturing process shown in FIG. 3. To form the circular seal member 85 into a convex curved surface that conforms to the valve-disk-side contact portion 40d, the PFA film 80x may be melted by resistance heating and molded in a mold as shown in FIG. 6(b). The PFA film 80x of the circular seal member 85 has a constant thickness and is molded into a convex curved surface.

[0043] According to this embodiment, a circular sealing member 85 made of cross-linked PTFE is joined to the valve body side contact portion 40d where the valve body 40 contacts the valve seat 13, and an annular sealing member 82 made of cross-linked PTFE is joined to the valve seat side contact portion 13a of the valve seat 13 where the valve body 40 contacts.This makes it possible to use cross-linked PTFE, which has excellent wear resistance and can reduce the amount of dust generated, only at the contact portion between the valve body 40 and the valve seat 13, and by using a fluororesin made of PFA or PTFE for the valve body 40 and the valve seat 13, it is possible to obtain a joining strength that exceeds the strength of a frictional joint due to polymer entanglement. Furthermore, according to this embodiment, the valve element side contact portion 40d is formed with a convex curved surface, so that the contact area between the valve element 40 and the valve seat 13 can be reduced, thereby reducing the amount of dust generated.

[0044] Figure 9 is an image diagram showing a method for forming the crosslinked PTFE sheet shown in Figure 2 and Figure 6. The arrows in the figure indicate the cutting direction. As shown in FIG. 9(a), the crosslinked PTFE sheet 80y is formed by orthogonally cutting the outer peripheral surface of a columnar or cylindrical rod material 90. In this way, by two-dimensionally cutting the outer peripheral surface of the columnar or cylindrical rod material 90, a long crosslinked PTFE sheet 80y of a predetermined width can be formed. As shown in FIG. 9(b), the cross-linked PTFE sheet 80y is formed by orthogonally cutting the end face of the rod material 90. In this way, the crosslinked PTFE sheet 80y can be formed to the size of the end face by two-dimensionally cutting the end face of the rod material 90. When two-dimensionally cutting the end face, the rod material 90 is not limited to a columnar or cylindrical shape, but may be any columnar or cylindrical shape.

[0045] FIG. 10 is a structural view showing an apparatus used in a joining step of joining a seal member to a valve body-side contact portion and a valve seat-side contact portion in a method for manufacturing a flow control valve of the present invention. FIG. 10(a) shows a joining step for joining the seal member 82 to the valve seat side contact portion 13a. A heater cable 101 is connected to the heating block 100, and power is supplied from the heater cable 101, so that an end 100a of the heating block 100 is directly heated by resistance heating. The heating block 100 is attached to a movable block 102. A welding pressure adjusting weight 103 and a movable block lifting cylinder 104 are attached to the movable block 102. The movable block lifting cylinder 104 is attached to a fixed plate 105, and the fixed plate 105 is supported by a support 106. The movable block 102 is pushed down by a welding pressure adjusting weight 103 and pulled up by a movable block lifting cylinder 104 . A temperature sensor 107 for detecting the temperature of the end 100a is provided at the end 100a of the heating block 100. In addition, a displacement sensor 108 for detecting the displacement of the movable block 102 is provided at the fixed plate 105. In the joining step of joining the seal member 82 to the valve seat contact portion 13a, the seal member 82 is placed on the valve seat contact portion 13a, and a heating block 100 that is directly heated by resistance heating is pressed against the seal member 82 side. By directly heating the sealing member 82 made of cross-linked PTFE with the heating block 100, the cross-linked PTFE is softened or semi-melted, and the valve seat-side abutment portion 13a made of PFA or PTFE is heated and melted at the contact interface with the sealing member 82 by the heat from the sealing member 82, thereby achieving a strong bond. Furthermore, by using cross-linked PTFE as the sealing member 82 and directly heating the heating block 100 by resistance heating, temperature control at the contact interface can be easily performed, and temperature control with high responsiveness to the melting surface temperature can be achieved.

[0046] FIG. 10(b) shows a joining step for joining the seal member 81 to the valve body side contact portion 40a. In the joining step of joining the seal member 81 to the valve body side contact portion 40a, the seal member 81 is placed on the valve body side contact portion 40a, and a heating block 100 that is directly heated by resistance heating is pressed against the seal member 81 side. By directly heating the sealing member 81 made of cross-linked PTFE with the heating block 100, the cross-linked PTFE is softened or semi-melted, and the valve body side abutment portion 40a made of PFA or PTFE is heated and melted at the contact interface with the sealing member 81 by the heat from the sealing member 81, thereby achieving a strong bond. Furthermore, by using cross-linked PTFE as the sealing member 81 and directly heating the heating block 100 by resistance heating, temperature control at the contact interface can be easily performed, and temperature control with high responsiveness to the melting surface temperature can be achieved.

[0047] FIG. 11 is an image diagram of the surface roughness of the sealing member before and after the bonding process shown in FIG. 10, where FIG. 11(a) shows the sealing member before the bonding process and FIG. 11(b) shows the sealing member after the bonding process. 11, the surfaces of the sealing members 81 and 82 can be flattened by pressing a heating block 100, which is directly heated by resistance heating, against the sealing members 81 and 82. The flattening of the surfaces of the sealing members 81 and 82 is mainly achieved by the PFA film 80x.

[0048] Fig. 12 is a diagram showing the melting molding process shown in Fig. 6(b). Note that the device configuration used in the molding process shown in Fig. 10 is the same as the configuration shown in Fig. 10, so the same reference numerals are used and the description will be omitted. In the device shown in FIG. 12, an end 100b of a heating block 100 is formed with an annular recess for forming an annular protrusion 83a. A laminated sheet of a PFA film 80x and a cross-linked PTFE sheet 80y is placed on a jig, and a heating block 100 that is directly heated by resistance heating is pressed against the cross-linked PTFE sheet 80y side. In this way, the annular protrusion 83a shown in FIG. 6(b) can be formed.

[0049] FIG. 13 is a graph showing the timing of ending heating in the bonding step shown in FIG. 10(a). In FIG. 13, the vertical axis represents the temperature of the heating block 100 detected by the temperature sensor 107 and the displacement of the heating block 100 detected by the displacement sensor 108, and the horizontal axis represents time. 10(a), the sealing member 82 is joined to the valve seat-side contact portion 13a, which has a large volume and continues to thermally expand because it is formed on the flow path-side body 10. When the valve seat-side contact portion 13a is heated, the flow path-side body 10 thermally expands, raising the position of the sealing member 82, while melting the sealing member 82 lowers the upper surface of the sealing member 82. That is, in the case of a large volume such as the flow path side body 10, thermal expansion continues even after welding of the sealing member 82 is completed, so the displacement detected by the displacement sensor 108 continues to increase, but the amount of displacement per unit time detected by the displacement sensor 108 decreases due to the melting of the sealing member 82. Therefore, by stopping the heating at a timing when the displacement amount per unit time of the heating block 100 becomes small, the bonding state between the seal member 82 and the valve seat side contact portion 13a can be controlled to be constant. In this way, the height of the sealing member 82 changes as the valve seat 13 thermally expands and the sealing member 82 melts, so the timing for stopping heating of the heating block 100 can be determined from the amount of displacement of the heating block 100 per unit time. Furthermore, when the volume of the valve body 40 is large, the bonding state between the sealing member 81 and the valve body side abutment portion 40b can be controlled to a constant state by stopping heating at a timing when the displacement amount per unit time of the heating block 100 becomes small. After the heating is stopped, the heating block 100 is cooled by blowing air onto it, or it may be cooled naturally.

[0050] FIG. 14 is a graph showing the timing of ending heating in the bonding step shown in FIG. 10(b). In FIG. 14, the vertical axis represents the temperature of the heating block 100 detected by the temperature sensor 107 and the displacement of the heating block 100 detected by the displacement sensor 108, and the horizontal axis represents time. In the joining process shown in FIG. 10(b), the seal member 81 is joined to the valve body side contact portion 40b. Since the valve body side contact portion 40b is formed on the valve body 40, it has a small volume and thermal expansion is saturated. That is, when the volume is small, such as in the case of the valve body 40, the valve body side abutment portion 40b is heated, and the valve body 40 thermally expands, causing the heating block 100 to move upward, and then the thermal expansion saturates and the sealing member 81 melts, causing the heating block 100 to move downward. Therefore, by stopping the heating at the timing when the displacement amount per unit time of the heating block 100 becomes negative, the bonded state between the seal member 81 and the valve body side contact portion 40b can be controlled to be constant. In this way, the valve body side abutment portion 40b thermally expands and the sealing member 81 melts, changing the height of the sealing member 81. Therefore, the timing for stopping heating of the heating block 100 can be determined from the amount of displacement of the heating block 100 per unit time. In addition, when the volume of the valve seat 13 is small, the bonding state between the sealing member 82 and the valve seat side abutment portion 13a can be controlled to a constant state by stopping heating at the timing when the displacement amount per unit time of the heating block 100 becomes negative. After the heating is stopped, the heating block 100 is cooled by blowing air onto it, or it may be cooled naturally.

[0051] The seal members 81, 82, 83, 84, 85 joined to either the valve body side contact portions 40a, 40b, 40c, 40d or the valve seat side contact portion 13a may be made of cross-linked PFA instead of cross-linked PTFE. By joining annular or circular sealing members 81, 82, 83, 84, 85 made of cross-linked PFA to the valve body side abutment portions 40a, 40b, 40c, 40d where the valve body 40 abuts against the valve seat 13, and to the valve seat side abutment portion 13a of the valve seat 13 where the valve body 40 abuts, it is possible to use cross-linked PFA, which has excellent wear resistance and can reduce the amount of dust generated, only at the contact portion between the valve body 40 and the valve seat 13, and by using a fluororesin made of PFA or PTFE for the valve body 40 and the valve seat 13, it is possible to obtain a joining strength that exceeds the strength of a frictional joint due to the entanglement of polymers. [Industrial Applicability]

[0052] The present invention is particularly suitable for a flow control valve used in the cleaning and peeling steps of silicon wafer processes in the field of semiconductor manufacturing. [Explanation of symbols]

[0053] 1, 2, 3, 4, 5 Flow control valve 10 Flow path side body 11 Inlet channel 12 Outlet channel 13 Valve seat 13a Valve seat side contact part 20 Drive side body 21, 21a, 21b Cylindrical space for piston 21X opening 22, 23 Air flow passage 30 pistons 31 Piston expansion section 40 Valve body 40a, 40b, 40c, 40d Valve body side contact portion 41 Convex part 50 Piston biasing means 60 diaphragm 61 Thick part 62 Membrane part 63 Fixed part 70 Diaphragm holder 80x PFA film 80y cross-linked PTFE sheet 81, 82, 83, 84, 85 Seal members 83a Annular protrusion 90 Rod material 100 Heating Block 101 Heating Cable 100a, 10b end 102 Movable Block 103 Welding pressure adjustment weight 104 Movable block lifting cylinder 105 Fixing Plate 106 Post 107 Temperature Sensor 108 Displacement Sensor

Claims

1. It has a flow path side body and a drive side body, the flow path side body has an inflow flow path through which a controlled fluid flows in, an outflow flow path through which the controlled fluid flows out, and a valve seat located between the inflow flow path and the outflow flow path; the driving-side body defines a cylindrical space therein for arranging a piston; A valve body is disposed at one end of the piston, an opening is formed at one end of the piston cylindrical space at a position facing the valve seat; a diaphragm disposed in the opening; The piston cylindrical space and the valve seat are separated by the diaphragm. The valve body is disposed on the valve seat side of the diaphragm. A flow control valve, the flow path side body and the valve body are formed of a fluorine-based resin such as PFA or PTFE, an annular or circular seal member made of cross-linked PTFE is joined to a valve element-side contact portion where the valve element contacts the valve seat and a valve seat-side contact portion of the valve seat where the valve element contacts, The sealing member is configured by laminating a cross-linked PTFE sheet on one surface of a PFA film, The PFA film is bonded to the valve body side contact portion or the valve seat side contact portion. A flow control valve characterized by:

2. an annular protrusion is formed on the seal member that is joined to either the valve body side contact portion or the valve seat side contact portion; The annular protrusion is formed by varying the thickness of the PFA film, The thickness of the crosslinked PTFE sheet was kept constant.

2. The flow control valve according to claim 1.

3. The valve body side contact portion is formed by an annular surface inclined in the radial direction, and the inner periphery of the annular surface is closer to the valve seat than the outer periphery of the annular surface.

3. The flow control valve according to claim 1 or 2.

4. The valve body side contact portion is formed by a convex curved surface, and the center of the convex curved surface is closer to the valve seat than the outer periphery of the convex curved surface.

3. The flow control valve according to claim 1 or 2.

5. A method for manufacturing the flow control valve according to any one of claims 1 to 4, comprising the steps of: In the joining step of joining the seal member to the valve body side contact portion and the valve seat side contact portion, The seal member is placed on the valve body contact portion or the valve seat contact portion, A heating block that is directly heated by resistance heating is pressed against the sealing member side. A method for manufacturing a flow control valve.

6. A method for manufacturing a flow control valve according to claim 1 or claim 2, comprising: In the seal member molding step of molding the seal member, a diffusion bonding step of overlapping and diffusion bonding the PFA film and the cross-linked PTFE sheet; a die-cutting step of die-cutting the laminated sheet of the PFA film and the cross-linked PTFE sheet diffusion-bonded in the diffusion bonding step into an annular or circular shape; have A method for manufacturing a flow control valve.

7. A method for manufacturing a flow control valve according to claim 2, comprising: In the seal member molding step of molding the seal member, a diffusion bonding step of overlapping and diffusion bonding the PFA film and the crosslinked PTFE sheet; a molding step of hot-molding a laminated sheet of the PFA film and the cross-linked PTFE sheet diffusion-bonded in the diffusion bonding step to form the annular protrusion; a die-cutting step of die-cutting the laminated sheet formed in the molding step into an annular or circular shape; have A method for manufacturing a flow control valve.

8. The crosslinked PTFE sheet is formed by two-dimensionally cutting the outer surface of a cylindrical or cylindrical rod material.

8. The method for manufacturing a flow control valve according to claim 6 or 7.

9. The cross-linked PTFE sheet is formed by orthogonally cutting the end surface of a rod material.

8. The method for manufacturing a flow control valve according to claim 6 or 7.

10. The sealing member bonded to either the valve body side contact portion or the valve seat side contact portion is made of cross-linked PFA instead of cross-linked PTFE.

2. The flow control valve according to claim 1.

11. In the bonding step, the surface of the sealing member is flattened by the heating block. The method for manufacturing a flow control valve according to claim 5 .

12. In the bonding step, heating is stopped at a timing when the displacement amount per unit time of the heating block becomes small. The method for manufacturing a flow control valve according to claim 5 .

13. In the bonding step, heating is stopped when the displacement amount per unit time of the heating block becomes negative. The method for manufacturing a flow control valve according to claim 5 .

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