Diaphragm valve and manufacturing method therefor

Abstract

In order to provide a diaphragm valve that suppresses the production of particles, and a manufacturing method therefor, this diaphragm valve 1A comprises: a diaphragm 3 having a valve body part 3a and a membrane part 3b that extends outward from the valve body part and can deform in a movement axis C direction; and a body 5 having a valve seat part 5a that the valve body part, moving reciprocally in the movement axis direction, comes into contact with and separates from, wherein one of the valve body part and the valve seat part is provided with a rib 31 protruding toward the other, the rib comprises a cross-linked PFA from the tip to the base thereof, and the tertiary carbon concentration M1 (mol%) in the tip and the the tertiary carbon concentration M2 (mol%) in the base satisfy the expressions M1≥0.01, M2≥0.01, and 0.8≤M1 / M2≤1.2. The manufacturing method comprises: a step for obtaining a cut piece of a crosslinked PFA film that results from crosslinking such that the tertiary carbon concentration is 0.01 mol% or greater; a step for reshaping the cut piece to obtain a reshaped product; and a step for obtaining a rib from the reshaped product.

Description

Diaphragm valve and its manufacturing method

[0001] The present invention relates to a diaphragm valve and a manufacturing method thereof, and more particularly to a diaphragm valve equipped with a diaphragm used for fluid control and a manufacturing method thereof.

[0002] Diaphragm valves can be used to control various fluids in a variety of situations, including controlling the flow and flow rate of chemicals used in semiconductor manufacturing. In this case, the diaphragm valve includes a body and a diaphragm formed from a fluororesin, such as polytetrafluoroethylene (PTFE) or perfluoroalkoxyalkane (PFA), due to their excellent chemical resistance and flexural durability. The body includes a valve chamber connected to multiple flow paths, and the diaphragm is reciprocally movable within the valve chamber along its axis of movement. As a result, reciprocating the diaphragm brings a valve element located at the bottom end of the diaphragm into and out of contact with a valve seat provided at the flow path opening within the valve chamber. This contact and separation allows the flow path including the valve seat to be opened or closed, or the size of the flow path to be changed.

[0003] In such diaphragm valves, the challenge is to prevent particle generation due to contact and separation between the valve disc and the valve seat. Specifically, particles can be considered to be particles that are formed by the wear and tear of the materials that make up the diaphragm valve. If particles are generated in the valve disc or valve seat, which are in the liquid-contacting area, they become mixed into the chemical liquid flowing through the diaphragm valve. Therefore, if the above-mentioned chemical liquid is, for example, a cleaning liquid used in semiconductor manufacturing, the cleaning liquid will contain particles, which can cause a problem of reduced cleanliness during cleaning. To address this problem, the technology described in Patent Document 1 below is known.

[0004] JP 2023-034749 A

[0005] The above-mentioned Patent Document 1 discloses a flow control valve in which the flow path side body and the valve disc are formed of a fluororesin made of PFA or PTFE, and annular or circular seal members made of cross-linked PTFE are joined to the valve disc side contact portion and the valve seat side contact portion, with the aim of achieving excellent wear resistance and reducing the amount of dust generation. However, since cross-linked PTFE is harder than non-cross-linked PTFE or PFA, when the valve disc part and the valve seat part, whose surfaces are only made of cross-linked PTFE, are brought into contact with and separated from each other, the non-cross-linked part deforms, creating a sliding area between the surface of the valve disc part and the surface of the valve seat part, resulting in the problem of generating particles in this sliding area.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a diaphragm valve and a manufacturing method thereof that can further suppress particle generation compared to conventional diaphragm valves.

[0007] That is, the present invention includes the following: [1] A diaphragm valve including a valve body portion and a diaphragm having a membrane portion extending outward from the valve body portion and deformable in the direction of the movement axis, and a body having a valve seat portion against which the valve body portion abuts and separates as the membrane portion reciprocates in the direction of the movement axis due to deformation of the membrane portion, wherein a rib protruding toward the other is provided on either the valve body portion or the valve seat portion, and the rib is made of cross-linked PFA from its tip to its base, and the tertiary carbon concentration at the tip is set to M １ (mol %), and the tertiary carbon concentration at the base is M ２ (mol %), M １ ≧0.01, M ２ ≧0.01 and 0.8≦M １ / M ２≦1.2. [2] The diaphragm valve according to [1] above, wherein one of the diaphragm and the body, which has the rib, has a base made of a non-crosslinked fluororesin, and an end portion integral with the base, which has the rib, and which is made of the crosslinked PFA. [3] The diaphragm valve according to [1] or [2] above, wherein the distance between the tip and the base of the rib is 250 μm or more. [4] The diaphragm valve according to any of [1] to [3] above, wherein the other of the valve body and the valve seat has an abutment portion that abuts against the rib provided on the other of the components, the abutment portion being made of a crosslinked fluororesin. [5] The diaphragm valve according to any of [1] to [4] above, wherein the rib is made of a remolded piece of a crosslinked PFA film that has been crosslinked to have a tertiary carbon concentration of 0.01 mol % or more. [6] The diaphragm valve according to [2] above, wherein the one component is cut from a composite material formed by integrating an intermediate material made of a non-crosslinked fluororesin that serves as the base and a re-molded piece of a crosslinked PFA film that has been crosslinked to have a tertiary carbon concentration of 0.01 mol% or more. [7] A method for manufacturing a diaphragm valve according to any of [1] to [6] above, comprising: a cutting step of obtaining a cut piece of a crosslinked PFA film that has been crosslinked to have a tertiary carbon concentration of 0.01 mol% or more; a re-molding step of re-molding the cut piece to obtain a re-molded product; and a forming step of obtaining the rib from the re-molded product. [8] A method for manufacturing a diaphragm valve according to [7] above, comprising an integration step of obtaining a composite material formed by integrating an intermediate material made of a non-crosslinked fluororesin and the re-molded product. [9] A manufacturing method for a diaphragm valve described in [8] above, wherein the integration process includes a cut piece accommodating process for accommodating the cut piece in a cavity provided in the intermediate material, and a firing process for melting the cut piece in the cavity to obtain the re-molded product and integrate the intermediate material and the re-molded product.

[10] A method for manufacturing a diaphragm valve as set forth in [8] or [9] above, wherein the integrating step includes an injection step of injecting a melt of the cut pieces into a cavity formed in the intermediate material to obtain the remolded product within the cavity and integrate the intermediate material with the remolded product.

[11] A method for manufacturing a diaphragm valve as set forth in any of [8] to

[10] above, wherein the integrating step includes a cut piece accommodating step of accommodating the cut pieces in a cavity formed in the intermediate material, and a compression molding step of compressing the cut pieces within the cavity to obtain the remolded product and integrate the intermediate material with the remolded product.

[12] A method for manufacturing a diaphragm valve as set forth in any of [7] to

[11] above, comprising a welding step of obtaining a composite material by welding an intermediate material made of a non-crosslinked fluororesin and the remolded product obtained in advance.

[0008] The diaphragm valve of the present invention can further suppress particle generation compared to conventional diaphragm valves.

[0009] That is, the rib is made of cross-linked PFA from the tip to the base, and the tertiary carbon concentration at the tip is M １ (mol%) and the tertiary carbon concentration at the root M ２ (mol%) and M １ ≧0.01, M ２ ≧0.01 and 0.8≦M １ / M ２ In a diaphragm valve that satisfies the condition of ≦1.2, the ribs are formed from a fully cross-linked PFA from the tip to the base, so deformation of the ribs is prevented when one part having the ribs comes into contact with the other part. １ and M ２ Compared with a diaphragm valve that does not satisfy the relationship above, the diaphragm valve of the present invention can suppress the generation of particles.

[0010] In the above-mentioned diaphragm valve, one of the ribbed components, either the diaphragm or the body, can have a base made of a non-crosslinked fluororesin and an end portion made of crosslinked PFA, which is integrated with the base and has ribs. In this case, a non-crosslinked fluororesin, which has superior flexural durability compared to crosslinked PFA, can be used as the base, thereby making it possible to improve the flexural durability of the membrane portion of the diaphragm in particular. Furthermore, since it is not necessary to form the entire diaphragm or body from crosslinked PFA, the manufacturing cost of the diaphragm valve can be reduced.

[0011] In the above-described diaphragm valve, the rib 31 can have a distance D1 (see FIG. 2) between the tip 31a and the base 31b of 250 μm or more. Normally, cross-linking a thick non-cross-linked PFA from both sides is difficult from the standpoint of radiation transmittance, but this can be achieved by the diaphragm valve manufacturing method described below. Furthermore, by providing a rib with this distance of 250 μm or more, more reliable flow control can be achieved than with a rib with this distance of less than 250 μm.

[0012] In the above-mentioned diaphragm valve, the other of the valve body and the valve seat has an abutment portion that abuts against a rib provided on the other of the components, and the abutment portion can be made of a cross-linked fluororesin. In this case, the cross-linked fluororesin, which has excellent wear resistance, is used as the mating material, resulting in a diaphragm valve with even greater durability.

[0013] In the above-mentioned diaphragm valve, the rib can be made from a remolded piece of a crosslinked PFA film crosslinked to a tertiary carbon concentration of 0.01 mol% or more. In other words, crosslinking a thick non-crosslinked PFA film to a tertiary carbon concentration of 0.01 mol% or more across the entire front and back is difficult from the standpoint of radiation transmittance. However, it is possible to irradiate a non-crosslinked PFA film of a thickness that allows this to be achieved, thereby obtaining a crosslinked PFA film with a tertiary carbon concentration of 0.01 mol% or more across the entire front and back. Furthermore, a crosslinked PFA member made from a remolded piece of this crosslinked PFA film can be made into a crosslinked PFA member that is uniformly crosslinked throughout, regardless of its thickness. Forming the rib from such a crosslinked PFA member with a uniform degree of crosslinking throughout prevents deformation of the rib itself, thereby significantly suppressing particle generation associated with contact and separation between the valve body and the valve seat.

[0014] In the above-mentioned diaphragm valve, one of the components can be cut from a composite material that integrates an intermediate material made of a non-crosslinked fluororesin base and a remolded cut piece of a crosslinked PFA film that has been crosslinked to a tertiary carbon concentration of 0.01 mol% or more. In this case, a non-crosslinked fluororesin that has superior flexural durability compared to crosslinked PFA can be used as the base, thereby improving the flexural durability of the membrane portion of the diaphragm in particular. Furthermore, since it is not necessary to form the entire diaphragm or body from crosslinked PFA, the manufacturing cost of the diaphragm valve can be reduced.

[0015] According to the method for manufacturing a diaphragm valve of the present invention, it is possible to manufacture a diaphragm valve that can further suppress the generation of particles compared to conventional diaphragm valves.

[0016] When a method includes a cutting step of obtaining cut pieces of a crosslinked PFA film crosslinked to a tertiary carbon concentration of 0.01 mol% or more, a remolding step of remolding the cut pieces to obtain a remolded product, and a forming step of obtaining ribs from the remolded product, a crosslinked PFA film uniformly crosslinked to a tertiary carbon concentration of 0.01 mol% or more can be obtained. Then, by remolding the cut pieces of this uniformly crosslinked crosslinked PFA film, a remolded product (crosslinked PFA member) can be obtained, which is made entirely of crosslinked PFA uniformly crosslinked to a tertiary carbon concentration of 0.01 mol% or more. Forming ribs from such a crosslinked PFA member with a uniform degree of crosslinking throughout can prevent deformation of the rib itself, thereby obtaining a diaphragm valve that can significantly suppress particle generation associated with contact and separation between the valve body portion and the valve seat portion.

[0017] The above-mentioned diaphragm valve manufacturing method can include an integration step of obtaining a composite material by integrating an intermediate material made of a non-crosslinked fluororesin with a remolded product. In this case, a non-crosslinked fluororesin having superior flexural durability compared to crosslinked PFA can be used, so that the membrane portion of the diaphragm can be formed from the intermediate material portion of the composite material, thereby improving the flexural durability of the membrane portion. Furthermore, since it is not necessary to form the entire diaphragm or body from crosslinked PFA, the manufacturing cost of the diaphragm valve can be reduced.

[0018] In the above-mentioned method for manufacturing a diaphragm valve, the integration step can include a cut piece accommodation step of accommodating cut pieces in cavities formed in the intermediate material, and a firing step of melting the cut pieces in the cavities to obtain a remolded product and integrating the intermediate material with the remolded product. Furthermore, in the above-mentioned method for manufacturing a diaphragm valve, the integration step can include an injection step of injecting the molten cut pieces into cavities formed in the intermediate material to obtain a remolded product in the cavities and integrating the intermediate material with the remolded product. Furthermore, in the above-mentioned method for manufacturing a diaphragm valve, the integration step can include a cut piece accommodation step of accommodating cut pieces in cavities formed in the intermediate material, and a compression molding step of compressing the cut pieces in the cavities to obtain a remolded product and integrating the intermediate material with the remolded product. Furthermore, the above-mentioned method for manufacturing a diaphragm valve can include a welding step of obtaining a composite material by welding an intermediate material made of a non-crosslinked fluororesin and a previously obtained remolded product. By carrying out these steps, a composite material can be obtained in which the intermediate material made of non-crosslinked fluororesin and the remolded product are integrated, and as a result, as described above, a diaphragm can be obtained that has ribs formed entirely from uniformly crosslinked crosslinked PFA and also has a membrane portion with excellent flexural durability.In addition, since it is not necessary to form the entire diaphragm or body from crosslinked PFA, the manufacturing cost of the diaphragm valve can be reduced.

[0019] The present invention will be further described in the following detailed description, which provides non-limiting examples of exemplary embodiments according to the present invention, and with reference to the mentioned drawings, in which like reference numerals refer to like parts throughout the several views of the drawings.

[0020] FIG. 1 is a longitudinal cross-sectional view of a diaphragm valve of Example 1; FIG. 2 is a longitudinal cross-sectional view of a diaphragm constituting the diaphragm valve; FIG. 3 is a longitudinal cross-sectional view of a body constituting the diaphragm valve; FIG. 4 is an explanatory diagram of the operation of the diaphragm valve, where (a) shows the closed state and (b) shows the open state; FIG. 5 is an explanatory diagram for explaining a manufacturing method of a diaphragm valve, where (a) shows a cross-linked PFA film, (b) shows a cutting process of the cross-linked PFA film, and (c) shows a re-molding process of the cut pieces of the cross-linked PFA film; FIG. 6 is an explanatory diagram for explaining a manufacturing method of a diaphragm valve (integrating process of an intermediate material and a re-molded product), where (a) shows a perspective view of the intermediate material and the re-molded product, and (b) shows a longitudinal cross-sectional view of the re-molded product housed in the cavity of the intermediate material; FIG. 7 is an explanatory diagram for explaining a manufacturing method of a diaphragm valve (rib forming process), where (a) shows a longitudinal cross-sectional view of a composite material, and (b) shows a longitudinal cross-sectional view of a diaphragm obtained by cutting the composite material. 1 is an explanatory diagram for explaining a manufacturing method (rib forming step) of a diaphragm valve of another embodiment, where (a) shows a longitudinal cross-sectional view of a composite material, and (b) shows a longitudinal cross-sectional view of a diaphragm obtained by cutting the composite material. FIG. 2 is an explanatory diagram for explaining a manufacturing method (rib forming step) of a diaphragm valve of yet another embodiment, where (a) shows a longitudinal cross-sectional view of a composite material, and (b) shows a longitudinal cross-sectional view of a diaphragm obtained by cutting the composite material. FIG. 3 is an explanatory diagram for explaining a manufacturing method (rib forming step) of a diaphragm valve of yet another embodiment, where (a) shows a longitudinal cross-sectional view of a composite material, and (b) shows a longitudinal cross-sectional view of a diaphragm obtained by cutting the composite material. FIG. 4 is an explanatory diagram for explaining a manufacturing method (rib forming step) of a diaphragm valve of yet another embodiment, where (a) shows a longitudinal cross-sectional view of a composite material, and (b) shows a longitudinal cross-sectional view of a diaphragm obtained by cutting the composite material. FIG. 5 is an explanatory diagram for explaining a manufacturing method (rib forming step) of a diaphragm valve of yet another embodiment (integration step of an intermediate material and a remolded product). FIG. 6 is a longitudinal cross-sectional view of a diaphragm constituting the diaphragm valve. FIG. 7 is a longitudinal cross-sectional view of a body constituting the diaphragm valve. FIG. 8 is an explanatory diagram for explaining the operation of the diaphragm valve, where (a) shows a closed state, and (b) shows an open state. 1A and 1B are explanatory diagrams for explaining a manufacturing method of a diaphragm valve, in which (a) shows a cross-linked PFA film, (b) shows a cutting process of the cross-linked PFA film, and (c) shows a re-molding process of the cut pieces of the cross-linked PFA film.

[0023] Figure 1 is an explanatory diagram for explaining a manufacturing method of a diaphragm valve (integrating process of an intermediate material and a remolded product), where (a) shows a perspective view of the intermediate material and the remolded product, and (b) shows a longitudinal cross-sectional view of the remolded product contained in the cavity of the intermediate material.

[0024] Figure 2 is an explanatory diagram for explaining a manufacturing method of a diaphragm valve (rib forming process), where (a) shows a longitudinal cross-sectional view of a composite material, and (b) shows a longitudinal cross-sectional view of a body obtained by cutting the composite material.

[0025] Figure 3 is an explanatory diagram for explaining a manufacturing method of a diaphragm valve of another form (rib forming process), where (a) shows a longitudinal cross-sectional view of a composite material, and (b) shows a longitudinal cross-sectional view of a body obtained by cutting the composite material.

[0026] Figure 4 is an explanatory diagram for explaining a manufacturing method of a diaphragm valve of yet another form (rib forming process), where (a) shows a longitudinal cross-sectional view of a composite material, and (b) shows a longitudinal cross-sectional view of a body obtained by cutting the composite material. 1A and 1B are explanatory views for explaining a method for manufacturing a diaphragm valve of yet another embodiment (a rib forming step), in which (a) shows a longitudinal cross-sectional view of a composite material, and (b) shows a longitudinal cross-sectional view of a body obtained by cutting the composite material. 1B are explanatory views for explaining a method for manufacturing a diaphragm valve of yet another embodiment (a rib forming step), in which (a) shows a longitudinal cross-sectional view of a composite material, and (b) shows a longitudinal cross-sectional view of a body obtained by cutting the composite material. 1C are explanatory views for explaining a method for manufacturing a diaphragm valve of yet another embodiment (a rib forming step), in which (a) shows a longitudinal cross-sectional view of a composite material, and (b) shows a longitudinal cross-sectional view of a body obtained by cutting the composite material. 1D are explanatory views for explaining a method for manufacturing a diaphragm valve of yet another embodiment (a rib forming step), in which (b rib forming step)

[0021] The matters set forth herein are for illustrative purposes only and are intended to provide an illustrative description of the embodiments of the present invention, with the aim of providing what is believed to be the most effective and easily understandable explanation of the principles and conceptual features of the present invention. In this regard, it is not intended to show structural details of the present invention beyond the extent necessary for a fundamental understanding of the present invention, and the description, taken together with the drawings, will make clear to those skilled in the art how some forms of the present invention may be actually embodied.

[0022] The present invention will be specifically described below with reference to Examples 1 and 2 with reference to the drawings.

[0023] 1, the diaphragm valve 1A of this embodiment comprises a diaphragm 3 having a valve element portion 3a and a membrane portion 3b that extends outward from the valve element portion 3a and is deformable in the direction of the movement axis C, and a body 5 having a valve seat portion 5a that contacts and separates from the valve element portion 3a, which reciprocates in the direction of the movement axis C due to deformation of the membrane portion 3b (see FIG. 4). Furthermore, the diaphragm valve 1A comprises a drive unit 7 that drives the diaphragm 3.

[0024] The body 5 is formed with a valve chamber 11 at the center of its upper portion, and with first and second flow paths communicating with the valve chamber 11. The body 5 is also formed with an annular valve seat 5a around the opening from the first flow path to the valve chamber 11, with which the diaphragm 3 (specifically, the valve body 3a) comes into and out of contact with. In this embodiment, the first flow path is formed as an inlet flow path 13, which extends from an inlet port 12 formed on one of the opposing side surfaces of the body 5 and opens at the center of the bottom of the valve chamber 11. The valve seat 5a is formed around the opening from the inlet flow path 13 to the valve chamber 11. The second flow path is formed with an outlet flow path 15, which extends from an outlet port 14 formed on the other opposing side surface of the body 5 and opens at the side surface of the valve chamber 11. However, the first and second flow paths are not limited to the above-described configuration, and may be, for example, configured such that a wear portion (dam portion) where a diaphragm contacts and separates between the flow paths is provided between the flow paths, or such that the flow paths are arranged in a straight line. Also, in this embodiment, the first and second flow paths are connected to the valve chamber 11, but the flow paths connected to the valve chamber 11 are not limited to this, and may include three or more flow paths.

[0025] The drive unit 7 is attached to the top of the body 5. The drive unit 7 also includes a drive unit housing 17 having a mechanism accommodating space formed therein, a cover member 18 attached to the top of the drive unit housing 17, a stem 19 connected to the diaphragm 3, and a drive mechanism housed in the mechanism accommodating space and driving the stem 19. In this embodiment, a cylinder portion is formed as the mechanism accommodating space within the drive unit housing 17, and the drive mechanism is composed of a piston 21 housed in the cylinder portion and a coil spring 22 as a biasing member.

[0026] The piston 21 has a piston body 21a slidably housed within the cylinder portion of the drive unit housing 17 and a guide shaft 21b extending upward from the piston body 21a. A stem 19 is connected to the piston body 21a and extends downward from the piston body 21a. The outer peripheral surface of the piston body 21a is in vertically slidable contact with the inner peripheral surface of the cylinder portion, dividing the internal space of the cylinder portion into an upper space S1 surrounded by the upper surface of the piston body 21a, the inner peripheral wall of the cylinder portion, and the ceiling surface of the cylinder portion (i.e., the lower surface of the cover member 18), and a lower space S2 surrounded by the lower surface of the piston body 21a, the inner peripheral wall of the cylinder portion, and the bottom surface of the cylinder portion (i.e., the bottom of the drive unit housing 17). The guide shaft 21b is slidably inserted into a through-hole provided through the cover member 18 and guides the up and down movement of the piston 21. The stem 19 is slidably inserted into a through-hole formed through the bottom of the drive unit housing 17 , extends to the valve chamber 11 , and has its tip connected to the diaphragm 3 .

[0027] The cover member 18 is formed with a vent hole 26 that communicates with the cylinder portion that defines the upper space S1. Ventilation is achieved between the upper space S1 and the outside through the vent hole 26. Furthermore, a working fluid supply port 27 that communicates with the bottom of the cylinder portion that defines the lower space S2 is formed on the side of the drive unit housing 17. Working fluid can be supplied from the working fluid supply port 27 into the lower space S2. Furthermore, a coil spring 22 is disposed in a compressed state between the lower surface of the cover member 18 (i.e., the ceiling surface of the cylinder portion) and the upper surface of the piston body 21a.

[0028] The driving unit 7 is not limited to the above-described configuration in which the diaphragm 3 is driven by using fluid pressure, but may be configured to drive the diaphragm 3 by using an electric actuator including, for example, a motor, a solenoid, etc. Furthermore, the diaphragm 3 may be manually driven.

[0029] The diaphragm 3 is positioned to close the upper opening of the valve chamber 11 and is fixed to the body 5. The diaphragm 3 includes a central valve element 3a, a thin-walled annular membrane 3b that supports the valve element 3a and is easily bent, and an outer peripheral edge 3c located on the outer periphery of the membrane 3b (see FIG. 2). The valve element 3a has a shape resembling a truncated cone connected to a cylinder, i.e., a cone shape with a tapered upper end. The valve element 3a is positioned so that its bottom surface faces the valve seat 5a. The bottom surface of the valve element 3a is provided with an annular rib 31 that protrudes toward the valve seat 5a. The membrane 3b is formed to extend radially outward from the outer periphery of the upper end of the valve element 3a, and the outer periphery of the membrane 3b has a generally circular shape. Furthermore, at least a portion of the outer peripheral edge 3c is sandwiched between the upper surface of the region surrounding the upper opening of the valve chamber 11 of the body 5 and the bottom surface of the actuator housing 17. In this manner, the diaphragm 3 separates the valve chamber 11 from the actuator 7, with the valve body portion 3a supported within the valve chamber 11 via the membrane portion 3b.

[0030] The shapes of the valve seat portion 5a, the valve body portion 3a and the rib 31 are not limited as long as the rib 31 of the valve body portion 3a, which moves back and forth in the direction of the movement axis C due to the deformation of the membrane portion 3b, can approach and separate from the valve seat portion 5a, thereby opening and closing the communication between the first flow path (specifically, the inlet flow path 13) and the second flow path (specifically, the outlet flow path 15).

[0031] A connecting hole 37 that opens upward is provided in the valve body portion 3a of the diaphragm 3. The connecting hole 37 includes a small diameter hole portion 37a located on the side closer to the drive unit 7 and a large diameter hole portion 37b that continues below the small diameter hole portion 37a. A locking portion 19a that is larger than the intermediate portion is provided at the tip (lower end) of the stem 19, and the diaphragm 3 and the stem 19 are connected by press-fitting the locking portion 19a through the small diameter hole portion 37a into the large diameter hole portion 37b, so that the diaphragm 3 (specifically the valve body portion 3a) can move toward and away from the valve seat portion 5a via the stem 19 as the piston 21 moves up and down.

[0032] As shown in FIG. 2 , the diaphragm 3 has a base 33a made of a non-crosslinked fluororesin and an end portion 33b made of crosslinked PFA, which is integrated with the base 33a and has a rib 31. Specifically, the base 33a, including the membrane portion 3b, is made of a non-crosslinked fluororesin, which is less expensive and has higher flexural durability than crosslinked PFA. The end portion 33b (specifically, the bottom of the valve body portion 3a), including the rib 31, is made of crosslinked PFA, which has high abrasion resistance and strength. Furthermore, the diaphragm 3 is cut from a composite material 45, which integrates an intermediate material 44 made of a non-crosslinked fluororesin that forms the base 33a, and a remolded product 43 (remolded product 43 that forms the end portion 33b) of a cut piece 42 of a crosslinked PFA film crosslinked to a tertiary carbon concentration of 0.01 mol % or more (see FIGS. 5 to 7 ).

[0033] The type of fluororesin constituting the non-crosslinked fluororesin is not limited, and may be tetrafluoroethylene [F ２ C=CF ２ ], hexafluoropropene [F ２ C=CF ２ -CF ３ ], difluoroethylene [H ２ C=CF ２ ], chlorotrifluoroethylene [F ２ C=CFCl], perfluoroalkoxyethylene (perfluoromethoxyethylene [F ２ C=CF-O-CF ３ ], perfluoroethoxyethylene [F ２ C=CF-O-CF ２ -CF ２Polymers (homopolymers or copolymers) using fluorine-substituted polymerizable compounds such as ethylene (non-fluorine-substituted ethylene) as monomers can be used. Among these, ethylene (non-fluorine-substituted ethylene) can be used as the copolymer monomer. Specifically, for example, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane, tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin), FEP (tetrafluoroethylene-hexafluoropropene copolymer resin), ETFE (ethylene-tetrafluoroethylene copolymer resin), PVDF (polyvinylidene fluoride, difluoroethylene polymer), PCTFE (polychlorotrifluoroethylene), ECTFE (ethylene-chlorotrifluoroethylene copolymer resin), etc., can be used. These may be used alone or in combination of two or more. Among these, non-crosslinked PTFE is preferred for the base 33a because it is less likely to melt when heated, can maintain its shape by gelation, and can reduce material costs.

[0034] Furthermore, crosslinking in fluororesin refers to the formation of carbon-carbon bonds between different polymer molecules that make up the fluororesin. Therefore, while non-crosslinked PFA typically does not contain tertiary carbon, crosslinked PFA does. Therefore, the presence or absence of tertiary carbon corresponds to the presence or absence of crosslinks within the PFA, and it can be seen that the higher the tertiary carbon concentration, the more crosslinks there are within the PFA. In the present invention, a tertiary carbon concentration of 0.01 mol% or higher is considered crosslinked. The upper limit of this tertiary carbon concentration is not limited, but is typically 0.7 mol% or less. Maintaining a tertiary carbon concentration of 0.7 mol% or less allows the mechanical strength of the crosslinked PFA to be maintained at a high level.

[0035] The tertiary carbon concentration of cross-linked PFA １９ F-NMR measurement (measurement device: solid １９The integral values ​​of the peaks A to G shown in Table 1 below are measured by F-NMR (Bruker Biospin AVANCE III-400WB), measurement conditions: 376 MHz, rotation speed: 27 kHz), and then the tertiary carbon concentration is calculated (based on Peak C) using the following calculation formula (1). The presence of tertiary carbon can be determined by the presence of Peak C and / or Peak G, but as described above, the tertiary carbon concentration is basically calculated according to Calculation Formula (1) using the peak intensity of Peak C. However, if Peak C is not detected and only Peak G is detected, the tertiary carbon concentration is calculated using the following Calculation Formula (2). The tertiary carbon concentration calculated using Calculation Formula (1) and the tertiary carbon concentration calculated using Calculation Formula (2) are usually substantially the same value.

[0036] In addition, [I Ａ／３ ], [I Ｂ／５ ], [I Ｃ／６ ], [I Ｄ／４ ], [I Ｅ／２ ], [I Ｆ／１ ] and [I Ｇ／１ ] are as follows: Ａ／３ ]: Equivalent F contained in the structure of "A" in Table 1 ＊ Since there are three peaks, the peak intensity based on "A" is "I Ａ ", then one F included in "A" ＊ The peak intensity for "I Ａ / 3" and this value is expressed as [I Ａ／３ ] is written as follows. Ｂ／５ ]: Equivalent F contained in the structure of "B" in Table 1 ＊ Since there are five, the peak intensity based on "B" is "I Ｂ ", then one F included in "B" ＊ The peak intensity for "I Ｂ / 5", and this value is Ｂ／５ ] is written as follows. Ｃ／６ ]: Equivalent F contained in the structure of "C" in Table 1 ＊ Since there are six peaks, the peak intensity based on "C" is "I Ｃ ", then one F included in "C" ＊ The peak intensity for "I Ｃ / 6", and this value is Ｃ／６ ] is written as follows. Ｄ／４ ]: Equivalent F contained in the structure of "D" in Table 1 ＊ Since there are four, the peak intensity based on "D" is "I Ｄ ", then one F included in "D" ＊ The peak intensity for "I Ｄ / 4" and this value is Ｄ／４ ] is written as follows. Ｅ／２ ]: Equivalent F contained in the structure of "E" in Table 1 ＊ Since there are two, the peak intensity based on "E" is "I Ｅ ", then one F included in "E" ＊ The peak intensity for "I Ｅ / 2" and this value is Ｅ／２ ] is written as follows. Ｆ／１ ]: Equivalent F included in the structure of "F" in Table 1 ＊ Since there is only one, the peak intensity based on "F" is "I Ｆ ", then one F included in "F" ＊ The peak intensity for "I Ｆ / 1", and this value is Ｆ／１ ] is written as follows. Ｇ／１ ]: Equivalent F contained in the structure of "G" in Table 1 ＊ Since there is only one, the peak intensity based on "G" is "I Ｇ ", then one F included in "G" ＊ The peak intensity for "I Ｇ / 1", and this value is Ｇ／１ ] should be written.

[0037] [Calculation formula (1)] I Ｃ／６ Tertiary carbon concentration based on Tertiary carbon concentration (mol%) = [I Ｃ／６ ] / {[I Ａ／３ ]+[I Ｂ／５ ]+[I Ｄ／４ ]+[I Ｅ／２ ]+[I Ｆ／１ ]+[I Ｇ／１ ]}×100 [Formula (2)] I Ｇ／１ Tertiary carbon concentration based on Tertiary carbon concentration (mol%) = {[I Ｇ／１]-[I Ａ／３ ]} / {[I Ｂ／５ ]+[I Ｃ／６ ]+[I Ｄ／４ ]+[I Ｅ／２ ]+[I Ｆ／１ ]}×100

[0038]

[0039] The rib 31 is made of cross-linked PFA from its tip to its base, and the tertiary carbon concentration at the tip is M １ (mol%), and the tertiary carbon concentration at the base is M ２ (mol %), M １ >0.01, M ２ >0.01 and 0.8≦M １ / M ２ ≦1.2. That is, the rib 31 has a tertiary carbon concentration M １ is more than 0.01 mol %, and at the same time, the tertiary carbon concentration M ２ In addition, these M １ and M ２ Ratio to (M １ / M ２ ) is 0.8 or more and 1.2 or less, and M １ and M ２ Therefore, the rib 31 is formed from a cross-linked PFA that is uniformly cross-linked from its tip to its base. The distance between the tip and base of the rib 31 is approximately 250 to 2000 μm, and is set to be 250 μm or more.

[0040] Ribs 31 made of crosslinked PFA that are uniformly crosslinked from tip to base can be formed in any manner, but can be formed from a remolded product 43 of a cut piece 42 of a crosslinked PFA film crosslinked to a tertiary carbon concentration of 0.01 mol% or more (see Figure 5). That is, for example, a thin film of non-crosslinked PFA less than 250 μm thick can be irradiated with radiation so that it reaches both the front and back of the film. On the other hand, for example, a thick film of non-crosslinked PFA greater than 250 μm thick makes it difficult for radiation to penetrate, resulting in a crosslinked PFA film with different degrees of crosslinking on the front and back. While it is possible to increase the radiation output to penetrate both the front and back of a non-crosslinked PFA film, this can result in different degrees of crosslinking on the front and back due to attenuation during penetration. Furthermore, using high-power radiation leads to a rapid increase in costs, making it difficult to adopt. Therefore, in order to obtain crosslinked PFA at low cost and with a high degree of freedom in shape while ensuring crosslinking, a thin film of non-crosslinked PFA less than 250 μm is irradiated with radiation so that it reaches both the front and back of the film to uniformly crosslink the film, and then the film is cut into pieces 42, which are then remolded to obtain crosslinked PFA with a uniformly crosslinked desired shape. Furthermore, for example, among fluororesins, PTFE is difficult to melt-form, regardless of whether it is crosslinked or not. In contrast, PFA can be melt-formed even after crosslinking, so it is possible to obtain block-shaped crosslinked PFA by remolding the cut pieces 42 of the crosslinked PFA film.

[0041] Meanwhile, the valve seat portion 5a of the body 5 is provided with an abutment portion 39 against which the rib 31 provided on the valve element portion 3a of the diaphragm 3 abuts. The abutment portion 39 is formed of an annular surface. However, the shape of the abutment portion 39 is not limited as long as the rib 31 can abut. As shown in FIG. 3 , the body 5 has a base portion 35a made of a non-crosslinked fluororesin and an end portion 35b integral with the base portion 35a, including the abutment portion 39, and made of a crosslinked fluororesin. That is, the base portion 35a (specifically, the portion of the body 5 having a larger volume than the end portion 35b) is made of non-crosslinked PTFE, which is cheaper than crosslinked fluororesin. The end portion 35b, including the abutment portion 39, is made of a crosslinked fluororesin, which has high wear resistance and strength. The non-crosslinked fluororesin constituting the base portion 35a can be any of the fluororesins described above. As the cross-linked fluororesin constituting the end portion 35b, any of the above-mentioned cross-linked fluororesins can be used, but cross-linked PFA is particularly preferred.

[0042] Next, a method for manufacturing the diaphragm valve 1A having the above-described configuration will be described. First, an intermediate member 44 having a cylindrical cavity 44a is prepared from a non-crosslinked fluororesin. PTFE can be used as this non-crosslinked fluororesin. In the first embodiment, a cup-shaped intermediate member 44 having a recess functioning as the cavity 44a at its upper end, as shown in FIG. 6, is prepared. The intermediate member 44 may be formed by any method, for example, by cutting a recess into the upper end of a rod-shaped body or plate compression-molded from a non-crosslinked fluororesin using a mold by a free baking method or hot molding method. Similarly, the intermediate member 44 may be formed by compression-molding a cup-shaped rod-shaped body or plate having a recess at its upper end using a mold by a free baking method or hot molding method. Furthermore, the intermediate member 44 does not need to be integrally formed. For example, it can be prepared by combining a cylindrical tubular body with a solid rod-shaped body or plate-shaped body (including a sheet-shaped body) disposed adjacent to the lower part of the cylindrical tubular body. In this case, the tubular body and the rod-shaped body or plate-shaped body may be joined by screwing or fitting of recesses and protrusions. Furthermore, when the tubular body and the rod-shaped body or plate-shaped body (including sheet-shaped ones) are integrally formed, they may be produced separately and then joined by welding. Welding can be performed by, for example, laser welding, hot plate welding, hot air welding, heating block welding, diffusion bonding, baking, etc. When the intermediate material 44 is produced from a rod-shaped body of non-crosslinked fluororesin, the rod-shaped body of non-crosslinked fluororesin may be produced by extrusion molding.

[0043] Meanwhile, a remolded product 43 having a shape and size that can be accommodated in the cavity 44a (recess) of the intermediate material 44, as shown in FIG. 6, is produced from the crosslinked PFA (remolding process). The remolded product 43 may be remolded at a location other than the cavity 44a, or may be remolded inside the cavity 44a. When remolding at a location other than the cavity 44a, a rod-shaped body whose outer circumferential shape is complementary to the inner circumferential surface of the cylindrical cavity 44a can be remolded from the crosslinked PFA in the same manner as the intermediate material 44 described above. In this case, a cut piece 42 of a crosslinked PFA film crosslinked to a tertiary carbon concentration of 0.01 mol% or more can be used as the raw material for the crosslinked PFA. That is, for example, as shown in FIG. 5(a), a crosslinked PFA film 41 can be formed by irradiating a film made of non-crosslinked PFA (non-crosslinked PFA film) with radiation. That is, by irradiating radiation to a thin film of non-crosslinked PFA, it is possible to obtain a crosslinked PFA film that is uniformly crosslinked on both sides. More specifically, by irradiating radiation in a temperature environment equal to or higher than the melting point of the non-crosslinked PFA with an acceleration voltage such that the absorbed dose on the back side of the irradiated surface is 20% or more (preferably 60% or more) of the absorbed dose on the front side with respect to the thickness of the non-crosslinked PFA film to be irradiated, it is possible to obtain a crosslinked PFA film having a tertiary carbon concentration of 0.01 mol% or more on both sides of the film.

[0044] Then, as shown in FIG. 5( b), the crosslinked PFA film that has been uniformly crosslinked across its front and back surfaces is cut to obtain cut pieces 42, thereby obtaining a crosslinked PFA material with greater shaping flexibility. Furthermore, as shown in FIG. 5( c), the cut pieces 42 of the crosslinked PFA film are placed in the cavity of a mold 46 having a predetermined shape, heated and melted, and then solidified to obtain a remolded product 43. This remolded product 43 can be shaped by cutting or other methods to fit into the cavity 44a of the intermediate material 44, and then placed in the cavity 44a. Furthermore, for example, from the standpoint of being able to heat-melt it, the height of the remolded product 43 may be approximately equal to or shorter than the depth of the cavity 44a, as long as it does not overflow the cavity 44a when heated and melted. The remolded product 43 can also be produced directly from the crosslinked PFA, for example, by extrusion molding or injection molding using a mold.

[0045] On the other hand, when reforming the remolded product 43 inside the cavity 44a, as shown in FIG. 11, the aforementioned cut pieces 42 of the crosslinked PFA film are placed in the cavity 44a (cut piece placement process) and heated and melted in the cavity 44a, thereby obtaining a remolded product 43 made of crosslinked PFA having a shape complementary to the inner circumferential surface of the cavity 44a. In this case, it is possible to heat and melt only the cut pieces 42 of the crosslinked PFA film placed in the cavity 44a, but it is also possible to heat the cavity 44a as well. That is, for example, the entire intermediate material 44 can be heated. This method is suitable when the intermediate material 44 is made of non-crosslinked PTFE. Non-crosslinked PTFE gels and does not melt even at the temperature at which crosslinked PFA is heated and melted. Therefore, the general shape of the intermediate material 44 and the cavity 44a can be maintained. Then, after the cut piece 42 of the cross-linked PFA film is heated and melted, it is remolded into a shape corresponding to the cavity 44a, and then cooled and solidified, at the same time the cavity 44a is also cooled and solidified, at which point the two (intermediate material 44 and remolded product 43) are integrated, resulting in a composite material 45 (firing process).

[0046] By reforming the remolded product 43 within the cavity 44a in this manner, the production of the remolded product 43 and the integration of the resulting remolded product 43 with the intermediate material 44 can be achieved through a single heating / melting / cooling / solidification process, thereby achieving excellent manufacturing efficiency. Furthermore, since a mold for obtaining the remolded product 43 is not required, diaphragm valves can be manufactured at low cost. Furthermore, when the remolded product 43 is obtained within the cavity 44a while heating the entire intermediate material 44, the occurrence of distortion and residual stress can be suppressed, resulting in excellent bonding strength between the two. This effect can be more pronounced by heating under no pressure (no particular pressure is applied). Furthermore, reforming the remolded product 43 within the cavity 44a allows bonding across the entire contact surface between the cavity 44a and the remolded product 43, resulting in a stronger bond between the intermediate material 44 and the remolded product 43 compared to composite materials with selective bonding locations, such as those formed by laser welding. Furthermore, it is possible to prevent a gap from being generated between the two even when an external force is applied to the composite material 45. As described above, when a rod-shaped composite material 45 obtained by remolding the remolded product 43 inside the cavity 44a was used as a test piece and a tensile test was performed by setting the intermediate material 44 and the remolded product 43 so as to separate them, it was confirmed that the joint between the intermediate material 44 and the remolded product 43 did not break, but broke at a location other than the joint.

[0047] In addition, when obtaining crosslinked PFA, it is possible to select, for example, non-crosslinked PFA powder as the starting material without using a non-crosslinked PFA film. However, when crosslinked PFA powder is obtained from non-crosslinked PFA powder, the crosslinked PFA powder is remolded, which poses the problem of the melt being more likely to contain gas when heated and melted. That is, the melt viscosity of crosslinked PFA is higher than that of non-crosslinked PFA, and the higher the degree of crosslinking, the higher the melt viscosity. Therefore, when prioritizing abrasion resistance, degassing requires effort and cost, so it is preferable to use cut pieces of crosslinked PFA film from the perspective of excellent degassing properties during heat melting. Furthermore, crosslinked PFA film can be pulverized into, for example, powder or fine particles, but cutting into cut pieces is less expensive. Furthermore, it is preferable to use cut pieces from the perspective of more effectively maintaining the mechanical strength obtained by crosslinking.

[0048] As described above, when the entire intermediate material 44 is heated to heat and melt the cut pieces 42 contained in the cavity 44a to obtain the remolded product 43 (firing process), the integration process can be performed simultaneously as the material cools and solidifies. However, the same effect can also be achieved by other methods, such as the following. That is, for example, a melt of the cut pieces 42 of the crosslinked PFA film can be injected into the cavity 44a of the intermediate material 44 to obtain the remolded product 43 within the cavity 44a, and the intermediate material 44 and the remolded product 43 can be integrated using an injection process. Alternatively, the cut pieces 42 of the crosslinked PFA film can be accommodated in the cavity 44a of the intermediate material 44 (cut piece accommodation process), and then the cut pieces 42 can be compressed within the cavity 44a to obtain the remolded product 43 and integrate the intermediate material 44 and the remolded product 43 (compression molding process). Heating can be performed simultaneously during this compression. The heating temperature can be set as required, and for example, the heating may be performed at a temperature lower than the melting point of the cross-linked PFA, or at a temperature higher than the melting point of the cross-linked PFA.

[0049] On the other hand, if the remolded product 43 is obtained separately, an integration step is performed to integrate the intermediate material 44 and the remolded product 43 contained in its cavity 44a (recess) to obtain a composite material 45. The integration may be performed by any method, but for example, the integration can be achieved by simultaneously heating both materials to a temperature equal to or higher than the melting point of the non-crosslinked fluororesin constituting the intermediate material 44 and the melting point of the crosslinked PFA constituting the remolded product 43, whichever is higher. That is, the intermediate material 44 and the remolded product 43 can be joined by melting at least one of them, at least on its surface.

[0050] The intermediate material 44 and the remolded product 43 can also be joined by welding. That is, this can be achieved by providing a welding process for obtaining a composite material in which the intermediate material 44 and the remolded product 43 are welded together. This welding can be performed by, for example, laser welding, hot plate welding, hot air welding, heating block welding, diffusion bonding, etc. Each of these methods can be said to be a method of melting at least a portion of the contact area between the intermediate material 44 and the remolded product 43 to weld them together.

[0051] 7(a) and 7(b) show a method for producing a diaphragm 3 from a composite material 45. By cutting the composite material 45 as shown by the dashed line in FIG. 7(a), a diaphragm 3 as shown in FIG. 7(b) can be produced. The diaphragm 3 shown in FIG. 7(b) is used in the diaphragm valve 1A shown in FIG. 1. In the diaphragm 3, the membrane portion 3b having the base portion 33a in the center is produced from an intermediate material 44 in the composite material 45, which is formed from a non-crosslinked fluororesin. Note that the non-crosslinked fluororesin that constitutes the intermediate material 44 is formed from PTFE, which has high flexural durability.

[0052] The end 33b of the diaphragm 3 is formed from cross-linked PFA, which generates little dust. In the composite material 45, the intermediate material 44 and the remolded material 43 are integrally bonded by sintering (integral melt molding). Therefore, the entire boundary surface (joint surface) between the base 33a and end 33b of the diaphragm 3 is integrally bonded. Therefore, even if the end 33b abuts against the valve seat 5a and is deformed by impact when the valve is closed, no gap is generated at the boundary surface between the base 33a and end 33b, preventing a decrease in strength due to liquid in the valve chamber 11 entering the gap. Furthermore, because both the intermediate material 44 and the remolded material 43 are heated and then cooled overall, thermal strain is suppressed, and a decrease in strength due to thermal strain is also suppressed.

[0053] Note that by cutting out the composite material 45 from an appropriate position, it is possible to change which areas of the component are made from different fluororesins. In other words, in Figures 7(a) and 7(b), only the area near the contact surface that contacts the valve seat portion 5a is made from cross-linked PFA, which has low dust-generating properties. However, as shown in Figures 8(a) and 8(b), by changing the cutting position, it is possible to make the end portion 33b made from cross-linked PFA larger and the base portion 33a made from non-cross-linked fluororesin smaller. On the other hand, as shown in Figures 10(a) and 10(b), it is possible to make only the rib 31 from cross-linked PFA, with the remaining portions made from non-cross-linked fluororesin. Furthermore, as shown in Figures 10(a) and 10(b), if only the rib 31 is made from cross-linked PFA, the size of the remolded product 43 within the composite material 45 can be kept small. Therefore, it is possible to obtain a diaphragm with excellent performance while reducing the amount of cross-linked PFA used, which is more expensive than non-cross-linked fluororesin.

[0054] Next, the operation and effect of the diaphragm valve 1A configured as described above will be described. As shown in FIG. 1 , during normal operation, when no working fluid is supplied to the actuator 7 from the working fluid supply port 27, the piston 21 of the actuator 7 is biased downward by the coil spring 22. As a result, the valve element 3a moves toward the valve seat 5a via the stem 19, and the rib 31 of the valve element 3a is pressed against the valve seat 5a, thereby closing the diaphragm valve 1A (see FIG. 4( a)). Accordingly, the membrane 3b supporting the valve element 3a also deforms away from the actuator 7. When working fluid is supplied to the working fluid supply port 27 of the actuator 7 from this state, the fluid pressure of the working fluid flowing into the lower space S2 of the cylinder acts upward on the piston body 21a, pushing the piston 21 up against the biasing force of the coil spring 22. At this time, air in the upper space S1 is released to the outside through the vent 26. As a result, the valve body 3a is moved away from the valve seat 5a via the stem 19, and the diaphragm valve 1A is placed in an open state (see FIG. 4B). Accordingly, the membrane portion 3b is also deformed in a direction approaching the drive unit 7. When the supply of working fluid to the working fluid supply port 27 is stopped, the piston 21 is again urged downward by the coil spring 22, and the rib 31 of the valve body 3a is pressed against the valve seat 5a, and the valve is again placed in a closed state.

[0055] As described above, in the diaphragm valve 1A of this embodiment, the valve body portion 3a is provided with the rib 31 that protrudes toward the valve seat portion 5a, and the rib 31 is made of cross-linked PFA from its tip to its base, and the tertiary carbon concentration at the tip is set to M １ (mol%), and the tertiary carbon concentration at the base is M ２ (mol %), M １ >0.01, M ２ >0.01 and 0.8≦M １ / M ２≦1.2. As a result, the ribs 31 are formed from cross-linked PFA that is uniformly cross-linked from their tip to base, which increases the wear resistance and strength of the ribs 31. Therefore, when the ribs 31 of the valve body 3a abut against the valve seat 5a when the valve is closed, the ribs 31 are prevented from deforming and rubbing against the valve seat 5a, thereby reducing the amount of particles generated.

[0056] Next, a diaphragm valve 1B of Example 2 will be described, but components that are substantially the same as those of the diaphragm valve 1A of Example 1 will be assigned the same reference numerals and detailed description thereof will be omitted, and only the differences between the two will be described in detail. The main difference between the two is that, while ribs 31 are provided on the valve body portion 3a of the diaphragm 3 in Example 1, ribs 31 are provided on the valve seat portion 5a of the body 5 in Example 2.

[0057] As shown in Figure 12, the diaphragm valve 1B of this embodiment comprises a diaphragm 3 having a valve element portion 3a and a membrane portion 3b that extends outward from the valve element portion 3a and is deformable in the direction of the movement axis C, and a body 5 having a valve seat portion 5a that contacts and separates from the valve element portion 3a, which reciprocates in the direction of the movement axis C due to deformation of the membrane portion 3b (see Figure 15). Furthermore, the diaphragm valve 1B comprises a drive unit 7 that drives the diaphragm 3.

[0058] The body 5 is formed with an annular valve seat 5a (see FIG. 14 ) around the opening from the first flow path to the valve chamber 11, against which the diaphragm 3 (specifically, the valve body 3a) comes into contact and separates. The valve seat 5a is provided with an annular rib 31 that protrudes toward the valve body 3a.

[0059] The shapes of the valve seat portion 5a, the valve body portion 3a and the rib 31 are not limited as long as the valve body portion 3a, which moves back and forth in the direction of the movement axis C due to the deformation of the membrane portion 3b, can approach and separate from the rib 31 of the valve seat portion 5a, thereby opening and closing the communication between the first flow path (specifically, the inlet flow path 13) and the second flow path (specifically, the outlet flow path 15).

[0060] As shown in FIG. 14 , the body 5 has a base 35a made of a non-crosslinked fluororesin and an end portion 35b made of crosslinked PFA, which is integrated with the base 35a and has ribs 31. Specifically, the base 35a (specifically, a portion of the body 5 having a larger volume than the end portion 35b) is made of a non-crosslinked fluororesin, which is less expensive than crosslinked PFA. The end portion 35b, including the ribs 31, is made of crosslinked PFA, which has high abrasion resistance and strength. Furthermore, the body 5 is cut from a composite material 45 that integrates an intermediate material 44 made of a non-crosslinked fluororesin that forms the base 35a and a remolded product 43 (i.e., the remolded product 43 that forms the end portion 35b) of a cut piece 42 of a crosslinked PFA film that has been crosslinked to have a tertiary carbon concentration of 0.01 mol % or more (see FIGS. 16 to 18 ).

[0061] The rib 31 is made of cross-linked PFA from its tip to its base, and the tertiary carbon concentration at the tip is M １ (mol%), and the tertiary carbon concentration at the base is M ２ (mol %), M １ >0.01, M ２ >0.01 and 0.8≦M １ / M ２ Therefore, the rib 31 is formed from cross-linked PFA that is uniformly cross-linked from its tip to its base, and has high abrasion resistance and strength.

[0062] The type of fluororesin constituting the non-crosslinked fluororesin is not limited, and as in Example 1, a polymer (homopolymer or copolymer) using tetrafluoroethylene, hexafluoropropene, difluoroethylene, chlorotrifluoroethylene, perfluoroalkoxyethylene, or the like as a monomer can be used. Specifically, a polymer (homopolymer or copolymer) using a fluorine-substituted polymerizable monomer can be used, and specifically, PTFE, PFA, FEP, ETFE, PVDF, PCTFE, ECTFE, or the like can be used. These may be used alone or in combination of two or more. Of these, non-crosslinked PTFE is preferred for the base 35a from the viewpoints of suppressing melting due to heating, maintaining shape by gelation, and reducing material costs.

[0063] On the other hand, the end portion 35b is formed from a crosslinked PFA having high abrasion resistance and strength, and the tertiary carbon concentration of the crosslinked PFA is preferably 0.01 mol% or more, and although there is no upper limit, it is usually 0.7 mol% or less, as in Example 1. The tertiary carbon concentration is also measured in the same manner as in Example 1.

[0064] In the case where the rib 31 is provided on the body 5, the rib 31 is made of cross-linked PFA from its tip to its base, as in the case of Example 1, and the tertiary carbon concentration at the tip is set to M １ (mol%), and the tertiary carbon concentration at the base is M ２ (mol %), M １ >0.01, M ２ >0.01 and 0.8≦M １ / M ２ ≦1.2. That is, the rib 31 has a tertiary carbon concentration M １ is more than 0.01 mol %, and at the same time, the tertiary carbon concentration M ２ In addition, these M １ and M ２ Ratio to (M １ / M ２ ) is 0.8 or more and 1.2 or less, and M １ and M ２Therefore, the rib 31 is formed from a cross-linked PFA that is uniformly cross-linked from its tip to its base. The distance between the tip and base of the rib 31 is approximately 250 to 2000 μm, and is set to be 250 μm or more.

[0065] The rib 31 made of crosslinked PFA uniformly crosslinked from tip to base can be formed in any manner, but can be formed from a remolded product 43 of a cut piece 42 of a crosslinked PFA film, as in Example 1 (see FIG. 16). In this case, the effects are also the same as in Example 1. That is, as shown in FIG. 16( a), a film made of non-crosslinked PFA (non-crosslinked PFA film) is irradiated with radiation to form a crosslinked PFA film 41. As shown in FIG. 16( b), the crosslinked PFA film uniformly crosslinked on both sides is cut to obtain cut pieces 42. Then, as shown in FIG. 16( c), the cut piece 42 of the crosslinked PFA film is placed in the cavity of a mold 46 having a predetermined shape, heated and melted, and then solidified to obtain a remolded product 43.

[0066] The bottom surface of the valve body portion 3a of the diaphragm 3 is provided with an abutment portion 39 against which a rib 31 provided on the valve seat portion 5a of the body 5 abuts. The abutment portion 39 is composed of an annular surface. However, the shape of the abutment portion 39 is not limited as long as the rib 31 can abut. As shown in FIG. 13 , the diaphragm 3 has a base portion 33a made of non-crosslinked PTFE and an end portion 33b integral with the base portion 33a, which includes the abutment portion 39 and is made of a crosslinked fluororesin such as PTFE or PFA. That is, the base portion 33a including the membrane portion 3b is made of non-crosslinked PTFE, which is cheaper and has higher flexural durability than crosslinked fluororesin. The end portion 33b (specifically, the bottom of the valve body portion 3a) including the abutment portion 39 is made of a crosslinked fluororesin, which has high wear resistance and strength.

[0067] Next, a method for manufacturing the diaphragm valve 1B having the above configuration will be described. First, as shown in Figures 17(a) and 17(b), an intermediate material 44 having a cylindrical cavity 44a is prepared from a non-crosslinked fluororesin, as in Example 1. Separately, as shown in Figures 16(a) to 16(c), a remolded product 43 that can be accommodated in the cavity 44a (recess) is prepared using a cut piece 42 of a crosslinked PFA film crosslinked to have a tertiary carbon concentration of 0.01 mol% or more. The remolded product 43 is then placed in the cavity 44a of the intermediate material 44, and the two are joined together by an appropriate method, as in Example 1, to obtain a composite material in which the intermediate material 44 and the remolded product 43 are integrated.

[0068] On the other hand, when reforming the remolded product 43 inside the cavity 44a, as in Example 1, as shown in FIG. 23, a cut piece 42 of crosslinked PFA film is placed in the cavity 44a (cut piece placement process) and heated and melted in the cavity 44a, thereby obtaining a remolded product 43 made of crosslinked PFA having a shape complementary to the inner circumferential surface of the cavity 44a. In this case, it is possible to heat and melt only the cut piece 42 of crosslinked PFA film placed in the cavity 44a, but it is also possible to heat the cavity 44a as well. That is, for example, the entire intermediate material 44 can be heated. This method is suitable for use when the intermediate material 44 is made of non-crosslinked PTFE. Non-crosslinked PTFE gels and does not melt even at the temperature at which crosslinked PFA is heated and melted. Therefore, the general shape of the intermediate material 44 and the cavity 44a can be maintained. Then, after the cut piece 42 of the cross-linked PFA film is heated and melted, it is remolded into a shape corresponding to the cavity 44a, and then cooled and solidified, at the same time the cavity 44a is also cooled and solidified, at which point the two (intermediate material 44 and remolded product 43) are integrated, resulting in a composite material 45 (firing process).

[0069] By reforming the remolded product 43 within the cavity 44a in this manner, the production of the remolded product 43 and the integration of the resulting remolded product 43 with the intermediate material 44 can be achieved through a single heating / melting / cooling / solidification process, thereby achieving excellent manufacturing efficiency. Furthermore, since a mold for obtaining the remolded product 43 is not required, diaphragm valves can be manufactured at low cost. Furthermore, when the remolded product 43 is obtained within the cavity 44a while heating the entire intermediate material 44, the occurrence of distortion and residual stress can be suppressed, resulting in excellent bonding strength between the two. This effect can be more pronounced by heating under no pressure (no particular pressure is applied). Furthermore, reforming the remolded product 43 within the cavity 44a allows bonding across the entire contact surface between the cavity 44a and the remolded product 43, resulting in a stronger bond between the intermediate material 44 and the remolded product 43 compared to composite materials with selective bonding locations, such as those formed by laser welding. Furthermore, it is possible to prevent a gap from being generated between the two even when an external force is applied to the composite material 45. As described above, when a rod-shaped composite material 45 obtained by remolding the remolded product 43 inside the cavity 44a was used as a test piece and a tensile test was performed by setting the intermediate material 44 and the remolded product 43 so as to separate them, it was confirmed that the joint between the intermediate material 44 and the remolded product 43 did not break, but broke at a location other than the joint.

[0070] FIGS. 18(a) to 18(b) and 19(a) to 19(b) show a method for fabricating a body 5 from a composite material 45. The body 5 shown in FIG. 18(b) can be fabricated by cutting the composite material 45 as indicated by the dashed lines in FIG. 18(a). The body 5 shown in FIG. 18(b) is used in the diaphragm valve 1B shown in FIG. 12. In the body 5, the end portion 35b on which the rib 31 is formed is fabricated from the remolded material 43 in the composite material 45, i.e., formed from a cross-linked PFA with low dust generation. Furthermore, the base portion 35a on which the inlet 12 and outlet 14 of the body 5 are formed is fabricated from the intermediate material 44 in the composite material 45, i.e., formed from a non-cross-linked fluororesin that is less expensive than cross-linked PFA. The inlet flow path 13 and the outlet flow path 15 are machined from the intermediate material 44 to extend from the inlet 12 and the outlet 14 to the valve chamber 11. On the other hand, the rib 31 is machined from the end portion 35b. Therefore, even if the contact portion 39 contacts the valve seat portion 5a when the valve is opened or closed, the generation of particles can be suppressed, and the contamination of the liquid in the valve chamber 11 due to the generated particles can be reduced.

[0071] According to the method shown in FIGS. 18(a) and 18(b), the inlet 12, inlet flow path 13, valve chamber 11, and outlet flow path 15 to outlet 14 are machined from the base 35a, while only the valve seat 5a is machined from the end 35b. This allows the body 5 to be manufactured at low cost while suppressing particle generation compared to the cutting method shown in FIGS. 19(a) and 19(b). Furthermore, as shown in FIGS. 20(a) and 20(b), after forming a remolded product 43 in the cavity 44a of the intermediate material 44, another intermediate material 48 can be formed using another non-crosslinked fluororesin. This method also allows the body 5 to be manufactured at low cost while suppressing particle generation compared to the cutting method shown in FIGS. 19(a) and 19(b). Furthermore, as shown in FIGS. 22(a) and 22(b), only the rib 31 can be made from crosslinked PFA, and the other portions can be made from non-crosslinked fluororesin. 22(a) and 22(b), when only the rib 31 is made of cross-linked PFA, it is possible to particularly reduce the size of the remolded product 43 within the composite material 45. As a result, it is possible to obtain a diaphragm with excellent performance while reducing the amount of cross-linked PFA used, which is more expensive than non-cross-linked fluororesin.

[0072] Furthermore, as shown in FIGS. 21( a) and 21(b), three cavities 44a can be formed in the intermediate material 44, corresponding to the inlet 12, the valve seat 5a, and the outlet 14, respectively. A remolded product 43 and another remolded product 49 made of cross-linked PFA can be formed in each of the three cavities 44a. The valve seat 5a can then be machined out of the remolded product 43, and the joints for the inlet 12 and the outlet 14 can be machined out of the other remolded product 49. In this case, dust generation (particle generation) associated with contact and separation between the abutment portion 39 and the valve seat 5a can be suppressed, while dust generation (particle generation) from the joints to which the tubes for the inlet 12 and the outlet 14 are connected can also be suppressed. At the same time, such a low-dust-generating body 5 can be manufactured at low cost.

[0073] Next, the operation and effect of the diaphragm valve 1B configured as described above will be described. As shown in FIG. 12 , during normal operation when no working fluid is supplied to the actuator 7 from the working fluid supply port 27, the piston 21 of the actuator 7 is biased downward by the coil spring 22. As a result, the valve element 3a moves toward the valve seat 5a via the stem 19 and presses against the rib 31 of the valve seat 5a, thereby closing the diaphragm valve 1B (see FIG. 15( a)). Accordingly, the membrane 3b supporting the valve element 3a also deforms away from the actuator 7. When working fluid is supplied to the working fluid supply port 27 of the actuator 7 from this state, the fluid pressure of the working fluid flowing into the lower space S2 of the cylinder acts upward on the piston body 21a, pushing the piston 21 up against the biasing force of the coil spring 22. At this time, air in the upper space S1 is released to the outside through the vent 26. As a result, the valve body 3a is moved away from the valve seat 5a via the stem 19, and the diaphragm valve 1B is placed in an open state (see FIG. 15(b)). Accordingly, the membrane portion 3b is also deformed in a direction approaching the drive unit 7. When the supply of working fluid to the working fluid supply port 27 is stopped, the piston 21 is again urged downward by the coil spring 22 and pressed down, and the valve body 3a is pressed against the rib 31 of the valve seat 5a, and the valve is again placed in a closed state.

[0074] As described above, in the diaphragm valve 1B of this embodiment, the valve seat 5a is provided with a rib 31 that protrudes toward the valve element 3a. The rib 31 is made of cross-linked PFA from its tip to its base. When the tertiary carbon concentration at the tip is M1 (mol %) and the tertiary carbon concentration at the base is M2 (mol %), the following relationships are satisfied: M1 > 0.01, M2 > 0.01, and 0.8 ≦ M1 / ​​M2 ≦ 1.2. Since the rib 31 is formed from cross-linked PFA that is uniformly cross-linked from its tip to its base, the wear resistance and strength of the rib 31 are enhanced. Therefore, when the valve element 3a abuts against the rib 31 of the valve seat 5a during valve closing, the rib 31 is prevented from deforming and rubbing against the valve element 3a, thereby reducing the amount of particles generated.

[0075] The present invention is widely used as a diaphragm valve having a diaphragm used for fluid control and a manufacturing method thereof.

[0076] 1A, 1B: diaphragm valve; 3: diaphragm; 3a: valve body portion; 3b: membrane portion; 3c: outer peripheral edge portion; 5: body; 5a: valve seat portion; 7: drive portion; 11: valve chamber; 12: inlet port; 13: inlet flow path; 14: outlet port; 15: outlet flow path; 17: drive portion housing; 18: cover member; 19: stem; 19a: locking portion; 21: piston; 21a: piston body; 21b: guide shaft; 26: vent hole; 27: working fluid supply port; 31: rib; 33a: base portion; 33b: end portion; 35a: base portion; 35b: end portion; 37: connecting hole; 37a: small diameter hole portion; 37b: large diameter hole portion; 39: abutment portion; 41: cross-linked PFA film; 42: cut piece of cross-linked PFA film; 43: Reformed product, 44: Intermediate material, 44a: Cavity, 45: Composite material, 46: Mold, 48: Other intermediate material, 49: Other reformed product, C: Movement axis, S1: Upper space, S2: Lower space.

Claims

1. A diaphragm valve comprising a valve body and a diaphragm having a membrane portion extending outward from the valve body and deformable in the direction of the axis of movement, and a body having a valve seat portion against which the valve body abuts and separates as the membrane portion reciprocates in the direction of the axis of movement due to deformation of the valve seat portion, wherein a rib protruding toward the other is provided on either the valve body portion or the valve seat portion, the rib is made of cross-linked PFA from its tip to its base, and the tertiary carbon concentration at the tip is set to M １ (mol%), and the tertiary carbon concentration at the base is M ２ (mol%), M １ ≧0.01, M ２ ≧0.01 and 0.8≦M １ / M ２ A diaphragm valve characterized in that it satisfies ≦1.

2.

2. A diaphragm valve as described in claim 1, wherein one of the diaphragm and the body, which has the rib, has a base made of non-crosslinked fluororesin, and an end portion which is integrated with the base, has the rib, and is made of the crosslinked PFA.

3. A diaphragm valve as set forth in claim 1, wherein the distance between the tip and the base of said rib is 250 μm or more.

4. A diaphragm valve as described in claim 1, wherein the other of the valve body portion and the valve seat portion has an abutment portion that abuts against the rib provided on the other of the components, and the abutment portion is made of cross-linked fluororesin.

5. The diaphragm valve according to claim 1, wherein said rib is made of a remolded cut piece of a crosslinked PFA film that has been crosslinked so that the tertiary carbon concentration is 0.01 mol % or more.

6. A diaphragm valve as described in claim 2, wherein the one of the parts is cut from a composite material that integrates an intermediate material made of non-crosslinked fluororesin that serves as the base and a remolded piece of crosslinked PFA film that has been crosslinked so that the tertiary carbon concentration is 0.01 mol % or more.

7. A method for manufacturing a diaphragm valve as described in any one of claims 1 to 6, comprising: a cutting step for obtaining cut pieces of a crosslinked PFA film crosslinked so that the tertiary carbon concentration is 0.01 mol% or more; a remolding step for remolding the cut pieces to obtain a remolded product; and a forming step for obtaining the ribs from the remolded product.

8. A method for producing a diaphragm valve as set forth in claim 7, further comprising an integration step of obtaining a composite material by integrating an intermediate material made of a non-crosslinked fluororesin with the remolded product.

9. A method for manufacturing a diaphragm valve as described in claim 8, wherein the integration process includes a cut piece accommodating process for accommodating the cut piece in a cavity provided in the intermediate material, and a sintering process for melting the cut piece in the cavity to obtain the remolded product and integrate the intermediate material with the remolded product.

10. A method for manufacturing a diaphragm valve as described in claim 8, wherein the integration process includes an injection process in which a molten material of the cut piece is injected into a cavity formed in the intermediate material to obtain the remolded product within the cavity and integrate the intermediate material with the remolded product.

11. A method for manufacturing a diaphragm valve as described in claim 8, wherein the integration process includes a cut piece accommodating process for accommodating the cut piece in a cavity provided in the intermediate material, and a compression molding process for compressing the cut piece within the cavity to obtain the remolded product and integrate the intermediate material with the remolded product.

12. A method for manufacturing a diaphragm valve as set forth in claim 7, further comprising a welding step of obtaining a composite material by welding an intermediate material made of a non-crosslinked fluororesin and the previously obtained remolded product.

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