Method for manufacturing seal material, and seal material

Abstract

To provide a method for manufacturing seal material in which a product having a stable finished dimension can be obtained by making both ends of a string-like rubber easier to be bonded.SOLUTION: A string-like rubber 10' of a predetermined length which is covered by fluorine-based resin having the thickness of 0.20 mm or less is prepared, bonding surfaces of the string-like rubber are bonded in the state where metal members are provided at least at both ends, at least the outer periphery of the bonding surfaces is covered by a fluororesin film 15 of the same material as fluorine-based resin coating, a connection part 14 covered by the fluororesin film and only the periphery of the connection part are arranged inside or in the vicinity of a high-frequency coil 22, the metal member is heated by the high-frequency coil to fuse the fluororesin film to form fluororesin coating, and the coating is cooled to take out an O-ring 10.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a sealing material and a sealing material. [Background technology]

[0002] Sealing materials in which an annular core material is coated with a fluororesin are known. For example, Patent Document 1 discloses an O-ring in which an annular core material made of heat-resistant rubber is coated with a fluororesin coating. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5339620 Summary of the Invention [Problem to be solved by the invention]

[0004] To coat a ring-shaped core material with a fluororesin, there is a method in which a string-shaped core material is coated with the fluororesin and both ends are joined together.

[0005] Heating equipment is generally used to join the connection parts, but the connection parts of annular sealing materials (such as O-rings) are relatively small, so there is a problem that they cannot be heated efficiently using a high-temperature press, for example.

[0006] The present invention has been made in view of the above points, and its object is to make it possible to efficiently heat and bond both ends of a string-shaped rubber that constitutes a sealing material. [Means for solving the problem]

[0007] In order to achieve the above object, in this invention, only the connecting portion of the rubber string and its surrounding area are heated and joined.

[0008] Specifically, in the first invention, A rubber string of a predetermined length covered with a fluorine-based resin having a thickness of 0.20 mm or less is prepared. The joining surfaces of the rubber strings are joined together with metal members provided at least at both ends thereof, At least the outer periphery of the joining surface of the rubber string is covered with a fluororesin film made of the same material as the fluororesin, Only the connection portion covered with the fluororesin film and the periphery of the connection portion are disposed near a high-frequency coil, a high-frequency coil is used to heat the metal member, thereby melting the fluororesin film and forming a fluororesin coating; The annular sealing material is then cooled and removed.

[0009] According to the above configuration, the metal member included in at least the connecting portion of the rubber string is heated by the high-frequency coil, melting the fluororesin film, eliminating the need for a mold and allowing the connecting portion to be as close to the high-frequency coil as possible. Furthermore, because the area subjected to high-frequency induction heating is limited, the extent of the heating effect is limited compared to when the entire portion is heated. This results in a high-quality sealing material. Furthermore, since the thickness of the fluororesin coating layer covering the rubber string is 0.20 mm or less, the sealing material is more easily deformed than coating layers with thicknesses greater than 0.20 mm, allowing it to be installed without requiring a large tightening force. The metal members may be embedded in both ends of the rubber string in advance or may be embedded during connection. "Very close" means as close as possible to the range of reach of the magnetic force of the high-frequency coil 22. In other words, the connecting portion does not necessarily have to be located inside the high-frequency coil; it may be located outside the coil within the reach of the magnetic force of the high-frequency coil 22.

[0010] In the second invention, in the first invention, When high-frequency induction heating is performed, the connection portion is disposed inside the high-frequency coil.

[0011] According to the above configuration, no mold is required, and the connection portion can be disposed inside the high-frequency coil, thereby enabling high-frequency induction heating to be performed more efficiently.

[0012] In a third aspect of the present invention, in the first or second aspect of the present invention, the metal member is a metal rod or metal pipe having the same outer diameter as the rubber string, The metal member connects both ends of the rubber string.

[0013] According to the above configuration, the metal member can be disposed at the connection portion of the rubber string with a simple configuration.

[0014] In a fourth aspect of the present invention, in the first or second aspect of the present invention, The metal member is made of a metal core wire that is embedded in the center of the rubber string in advance.

[0015] According to the above configuration, the metal member can be disposed at the connection portion of the rubber string simply by embedding the metal core wire when molding the rubber string.

[0016] In a fifth aspect of the present invention, in the first or second aspect of the present invention, The metal member is made of a metal pin embedded in the rubber string so as to connect both ends of the rubber string.

[0017] According to the above configuration, the metal member can be easily arranged by simply embedding the metal pins into both ends of the rubber string when joining the rubber string.

[0018] In a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, The metal member is made of a magnetic material.

[0019] According to the above-mentioned configuration, the metal member made of a magnetic material can be efficiently heated by the high frequency coil, so that a high-quality sealing material that is less affected by heating can be obtained.

[0020] The sealing material of the seventh invention is An annular core material; a coating layer formed of a fluorine-based resin that coats the core material; a metal member embedded in at least a portion of the circumferential direction, The thickness of the coating layer is 0.2 mm or less.

[0021] According to the above configuration, the metal member included in at least the connecting portion of the rubber string is heated by the high-frequency coil, melting the fluororesin film, eliminating the need for a mold and allowing the connecting portion to be as close to the high-frequency coil as possible. Furthermore, because the portion subjected to high-frequency induction heating is limited, the range of the heating effect is limited compared to when the entire portion is heated. This results in a high-quality sealing material. Furthermore, because the thickness of the coating layer made of fluororesin that covers the rubber string is 0.20 mm or less, the sealing material is more easily deformed than those with coating layers thicker than 0.20 mm, and can be installed without requiring a large tightening force.

[0022] In an eighth aspect of the present invention, in the seventh aspect of the present invention, The metal member is made of a magnetic material.

[0023] According to the above-mentioned configuration, the metal member made of a magnetic material can be efficiently heated by the high frequency coil, so that a high-quality sealing material that is less affected by heating can be obtained.

[0024] In a ninth aspect of the present invention, in the seventh or eighth aspect of the present invention, The fluorine-based resin includes a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer resin.

[0025] According to the above-mentioned configuration, a sealing material can be obtained that can be suitably used as a sealing means in applications requiring plasma resistance or chemical resistance.

[0026] In a tenth aspect of the present invention, in any one of the seventh to ninth aspects of the present invention, The core material is made of silicone rubber.

[0027] According to the above configuration, the sealing material has an appropriate softness, so that sealing performance can be easily ensured without applying a large tightening force.

[0028] In an eleventh aspect of the present invention, in any one of the seventh to tenth aspects of the present invention, The line load at 25% compression is 3.0 N / mm or less.

[0029] The above configuration provides a highly marketable sealing material coated with a fluororesin that does not require a large tightening force during installation. The "linear load at 25% compression" is calculated by dividing the load required to compress the O-ring 10 by 25% in the thickness direction by the average circumference, i.e., the sum of the inner diameter and thickness, multiplied by pi. [Effects of the Invention]

[0030] As described above, according to the present invention, both ends of a rubber string can be efficiently joined while suppressing the influence of heat during joining, thereby obtaining a high-quality sealing material. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a cross-sectional view showing an O-ring to be manufactured according to an embodiment of the present invention. [Figure 2] FIG. 4 is an enlarged cross-sectional view showing a connection portion. [Figure 3] 10 is an enlarged cross-sectional view showing a connection portion according to Modification 1. FIG. [Figure 4] FIG. 10 is an enlarged cross-sectional view showing a connection portion according to Modification 2. [Figure 5] 1 is a perspective view showing a heating device used in a method for manufacturing a sealing material according to an embodiment of the present invention. [Figure 6] 3 is a flowchart showing a method for manufacturing a sealing material according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] The embodiments will be described in detail below.

[0033] 1 shows an O-ring 10 as a sealing material according to an embodiment. The shape of the O-ring 10 is specified in JIS B2401-1:2012, and is, for example, an inner diameter of 30 mm to 500 mm and a thickness of 2 mm to 10 mm.

[0034] The O-ring 10 according to the embodiment includes a ring-shaped core material 11 (a rubber string) and a coating layer 12 that coats the core material 11. The coating layer 12 is made of a fluororesin. This makes the O-ring 10 suitable for use as a sealing means in applications requiring plasma resistance or chemical resistance, such as semiconductor manufacturing equipment. The thickness of the coating layer 12 is 0.20 mm or less.

[0035] According to the O-ring 10 of this embodiment, the thickness of the coating layer 12 formed of a fluororesin that coats the core material 11 is 0.20 mm or less, so that it can be attached without requiring a large tightening force. The inventors studied the reason why a large tightening force is required when attaching the O-ring 10, whose core material 11 is coated with the fluororesin coating layer 12, and as a result, they focused on the fact that a large repulsive force is generated in the O-ring 10 when compressed, and arrived at the idea of ​​controlling this repulsive force by the thickness of the coating layer 12.

[0036] The core 11 is preferably made of cross-linked rubber. Examples of rubbers that can be used to form the core 11 include silicone rubber, nitrile rubber, hydrogenated nitrile rubber, fluororubber, ethylene propylene copolymer rubber, ethylene propylene diene terpolymer rubber, and acrylic rubber. Of these, silicone rubber is preferred as the rubber used to form the core 11, as it does not require a large tightening force during installation. From the same perspective, the hardness of the rubber that forms the core 11 is preferably A40 or more and A50 or less, more preferably A43 or more and A47 or less. This hardness is measured using a Type A durometer based on JIS K6253-3:2023 on the core 11 before it is coated with the coating layer 12.

[0037] Examples of fluorine-based resins that form the coating layer 12 include thermoplastic resins such as tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA) resin, polytetrafluoroethylene (PTFE) resin, tetrafluoroethylene hexafluoropropylene copolymer (FEP) resin, and ethylene tetrafluoroethylene copolymer (ETFE) resin. The fluorine-based resin that forms the coating layer 12 preferably contains one or more of these, and preferably contains PFA resin from the viewpoints of excellent plasma resistance and not requiring a large tightening force during installation.

[0038] The thickness of the coating layer 12 is 0.20 mm or less, but from the viewpoint of not requiring a large tightening force during installation, it is preferably 0.15 mm or less, more preferably 0.10 mm or less, and even more preferably 0.06 mm or less. On the other hand, from the viewpoint of processability of coating the core material 11 with the fluororesin coating layer 12, the thickness of the coating layer 12 is preferably 0.02 mm or more, and more preferably 0.03 mm or more.

[0039] The ratio of the thickness of coating layer 12 to the diameter of O-ring 10 is preferably 7% or less, more preferably 6% or less, even more preferably 4% or less, and even more preferably 2% or less, from the viewpoint of not requiring a large tightening force during installation. The ratio of the thickness of coating layer 12 to the diameter of O-ring 10 is preferably 0.5% or more, more preferably 1% or more, from the viewpoint of processability of coating core material 11 with fluororesin coating layer 12.

[0040] The hardness of the O-ring 10 according to the embodiment is preferably A60 to A80, more preferably A65 to A77, from the viewpoint of not requiring a large tightening force during installation. This hardness is also measured by a type A durometer in accordance with JIS K6253-3:2023 for the O-ring 10 after coating with the coating layer 12.

[0041] The line load at 25% compression of the O-ring 10 according to the embodiment is preferably 3.0 N / mm or less, and more preferably 2.0 N / mm or less, from the viewpoint that a large tightening force is not required during installation. This line load at 25% compression is calculated by dividing the load required to compress the O-ring 10 by 25% in the thickness direction by the average circumferential length, that is, the sum of the inner diameter and thickness multiplied by pi.

[0042] Next, a method for manufacturing the O-ring 10 according to the embodiment will be described.

[0043] First, in a preparation step, a string-like core material 11 is produced. The string-like core material 11 made of rubber can be produced by extrusion molding, for example.

[0044] Then, as shown in step S01 of Figure 6, although not shown in detail, the string-shaped core material 11 (rubber string) is passed through a head attached to an extrusion molding machine, and the surface of the core material 11 is coated with a coating layer 12 of fluorine-based resin along its length by a so-called coating extrusion molding method, thereby producing a long string-shaped rubber 10'.

[0045] When the string-shaped core material 11 is coated with the fluororesin coating layer 12, the string-shaped core material 11 is inserted into a nipple and moved forward (downstream) along its length at a constant speed. Also, molten fluororesin is supplied to the die from the extrusion molding machine.

[0046] A predetermined length is then cut from the collected rubber string 10', and both ends are joined to form a ring, thereby producing the O-ring 10. The joining method will be described in detail below.

[0047] As described above, a rubber string 10' having a predetermined length and covered with a fluorine-based resin coating layer 12 having a thickness of 0.20 mm or less is prepared.

[0048] Next, in the metal member placement step, a metal member 16 made of a metal rod or metal pipe with the same outer diameter as the rubber strings 10' is placed between the joining surfaces of the rubber strings 10', as shown in Fig. 2. The metal rod or metal pipe is made of a magnetic material such as iron or nickel. However, as shown in Figs. 3 and 4 described below, the configuration of the metal member is not limited to this.

[0049] At this time, for example, a two-component curing liquid silicone rubber is applied as an adhesive between the rubber strings 10' and the metal member 16. The adhesive is not limited to this.

[0050] Next, in the fluororesin film winding step shown in step S02 of Fig. 6, with the metal member 16 joined, the connection portion 14, including at least the joining surface including the metal member 16, is covered with a fluororesin film 15 made of the same material as the resin coating. The thickness of the fluororesin film 15 is not particularly limited, but may be the same as that of the coating layer 12, for example. Even if the fluororesin film 15 becomes too thick, it can be ground off after molding, so the thickness can be set to be relatively large.

[0051] Next, a connection portion heating step is performed. In step S03, as shown in FIG. 5, the connection portion 14 is placed inside the high-frequency coil 22. At this time, since there is no need to cover the connection portion 14 with a mold, the rubber string 10' in a ring-like state can be passed through the gap between the windings of the high-frequency coil 22. For example, if the gap between the windings of the high-frequency coil 22 is 5 mm, the rubber string 10' can easily pass through if it has a diameter of 3 mm. Note that if the gap between the windings of the high-frequency coil 22 is small, the rubber string 10' may be placed as close as possible to the outside of the windings of the high-frequency coil 22, where it can be heated efficiently.

[0052] Next, in step S04, the connection portions 14 are coated with a fluororesin by high-frequency induction heating. For example, only the connection portions 14 and the periphery of the connection portions 14 covered with the fluororesin film 15 are heated from room temperature to 300°C by high-frequency heating using the heating device 20 for 2 minutes, and then held at that temperature for 1 minute. Here, it is not necessary to heat the entire rubber string 10', so there is no need to heat the already coated coating layer 12 over a wide area, and quality is less likely to deteriorate.

[0053] Next, in the cooling step of step S05, the connection portion 14 is cooled. In this embodiment, the connection portion 14 is cooled by natural cooling. In addition to natural cooling, the cooling step can also be performed by air cooling using a fan or cooling with a liquid such as distilled water.

[0054] Next, in the removal step of step S06, the O-ring 10 is removed from the high frequency coil 22, thereby obtaining the annular O-ring 10.

[0055] In some cases, if the fluororesin film 15 portion protrudes more than the other outer surfaces, a finishing process such as polishing is carried out so that the entire surface is smooth.

[0056] In this embodiment, the metal member 16 included in at least the connecting portion 14 of the rubber string 10' is heated by the high-frequency coil 22, melting the fluororesin film 15. This eliminates the need for a mold and allows the connecting portion 14 to be as close to the high-frequency coil 22 as possible. Since the portion that is subjected to high-frequency induction heating is limited, the range of the heating effect is more limited than when the entire ring is heated. This results in a high-quality O-ring 10. Furthermore, since the thickness of the coating layer 12 formed of a fluororesin that coats the rubber string 10' is 0.20 mm or less, the O-ring 10 is more easily deformed than an O-ring with a coating layer thickness greater than 0.20 mm, and thus can be attached without requiring a large tightening force.

[0057] Furthermore, since the metal member 16 made of a magnetic material can be heated extremely efficiently by the high frequency coil 22, a high quality O-ring 10 that is less affected by heating can be obtained.

[0058] In this embodiment, the rubber strings 10' are made of silicone rubber, which provides a moderate degree of softness, and therefore the O-ring 10 can easily ensure sealing performance without applying a large tightening force.

[0059] In this embodiment, the fluororesin contains tetrafluoroethylene perfluoroalkyl vinyl ether copolymer resin, so the O-ring 10 can be suitably used as a sealing means in applications requiring plasma resistance or chemical resistance.

[0060] The O-ring 10 of this embodiment has a line load of 3.0 N / mm or less when compressed by 25%, so it can exhibit sealing performance without requiring a large tightening force.

[0061] As described above, according to the present invention, both ends of the rubber string 10' can be efficiently joined while suppressing the influence of heat during joining, thereby obtaining a high-quality O-ring 10.

[0062] -Variation 1- 3 shows a connection portion 14' according to a first modified example of the embodiment of the present invention, which differs from the above embodiment in that the configuration of the metal member 16' is different. In the following modified examples, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0063] That is, in this modification, the metal member 16' is made of a metal core wire embedded in the center of the rubber string 10' when it is extruded. For example, if the diameter of the rubber string 10' is 3 mm, the metal core wire has a diameter of 1 mm, but is not limited to this. The metal core wire is made of a magnetic material such as iron wire or nickel wire.

[0064] In this modification, the metal member 16' is embedded in advance inside the rubber string 10', making the joining process easy. Also, since the metal core wire is embedded around the entire circumference, the reaction force of the O-ring 10 is almost constant around the entire circumference, making it easy to handle.

[0065] -Variation 2- FIG. 4 shows a connection portion 14'' according to a second modification of the embodiment of the present invention, which differs from the above embodiment in that the configuration of a metal member 16'' is different.

[0066] That is, in this modified example, the metal member 16'' is made of a single metal positioning pin. In this modified example, the metal member 16'' is preferably made of a flexible magnetic material. It may be bent in advance into an arc shape to match the diameter of the O-ring 10. The metal positioning pin is made of a magnetic material such as iron wire or nickel wire.

[0067] When joining the rubber string 10', it is inserted into the center of the core material 11 on one end side, and then or before that, adhesive is applied to the joining surface, and the other end of the metal member 16'' is inserted into the center of the core material 11 on the other end side. The connection part 14'' is then covered with a fluororesin film 15. Since the metal member 16'' is present in the center of both ends during joining, the joining work is easy. For example, if the diameter of the rubber string 10' is 3 mm, the diameter of the metal positioning pin should be 1 mm, but this is not limited to this.

[0068] In this modification, the metal members 16'' are simply embedded in both ends of the core material 11 when joining the rubber strings 10', making the joining work easy.

[0069] (Other embodiments) The present invention may be configured as follows in relation to the above embodiment.

[0070] That is, in the above embodiment, the O-ring 10 is shown as an example of the sealing material, but it is not particularly limited to this, and any other annular sealing material may be used.

[0071] In the above embodiment, the surface of the string-shaped core material 11 is covered with a fluororesin covering layer 12 by a covering extrusion molding method, but this is not particularly limited to this, and for example, the covering layer 12 may be formed by applying a fluororesin coating to the surface of the string-shaped core material 11.

[0072] In the manufacturing method of the O-ring 10 according to the embodiment, the surface of the string-shaped core material 11 before being coated with the coating layer 12 may be subjected to a surface treatment to improve adhesion to the fluororesin coating layer 12. By performing such a surface treatment on the surface of the string-shaped core material 11 before being coated with the coating layer 12, the adhesion of the core material 11 to the fluororesin coating layer 12 is improved, and as a result, the occurrence of wrinkles on the surface of the thin coating layer 12 having a thickness of 0.20 mm or less can be suppressed. Examples of such surface treatments include a primer treatment, an Itro treatment, and a plasma treatment.

[0073] In the manufacturing method of the O-ring 10 according to the embodiment, before coating the string-shaped core material 11, the surface of the molten fluororesin R that is to come into contact with the string-shaped core material 11 may be subjected to plasma treatment in order to improve adhesion to the string-shaped core material 11. As a result of this, the surface of the coating layer 12 that comes into contact with the core material 11 is subjected to plasma treatment, which not only improves the adhesion of the fluororesin coating layer 12 to the core material 11 but also suppresses the occurrence of wrinkles on the surface of the coating layer 12.

[0074] It should be noted that the above-described embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or uses. [Explanation of symbols]

[0075] 10' Rubber String 10 O-ring (sealing material) 11 Core material 12 Covering layer 14,14',14'' connection 15 Fluorine resin film 16,16',16'' Metal parts 20 Heating device 22 High frequency coil

Claims

1. A string-shaped rubber of a predetermined length covered with a fluorine-based resin having a thickness of 0.20 mm or less is prepared, The joining surfaces of the rubber strings are joined together with metal members provided at least at both ends thereof, At least the outer periphery of the joining surface of the rubber string is covered with a fluororesin film made of the same material as the fluororesin, Only the connection portion covered with the fluororesin film and the periphery of the connection portion are disposed near a high-frequency coil, a high-frequency coil is used to heat the metal member, thereby melting the fluororesin film and forming a fluororesin coating; Cool and remove the annular seal A method for producing a sealing material comprising the steps of:

2. When high-frequency induction heating is performed, the connection portion is disposed inside the high-frequency coil. The method for manufacturing a sealing material according to claim 1 .

3. the metal member is a metal rod or metal pipe having the same outer diameter as the rubber string, The metal member connects both ends of the rubber string.

3. The method for manufacturing a sealing material according to claim 1 or 2.

4. The metal member is made of a metal core wire that is embedded in the center of the rubber string in advance.

3. The method for manufacturing a sealing material according to claim 1 or 2.

5. The metal member is made of an embedded metal pin that connects both ends of the rubber string.

3. The method for manufacturing a sealing material according to claim 1 or 2.

6. The metal member is made of a magnetic material.

3. The method for manufacturing a sealing material according to claim 1 or 2.

7. An annular core material; a coating layer formed of a fluorine-based resin that coats the core material; a metal member embedded in at least a portion of the circumferential direction, The thickness of the coating layer is 0.2 mm or less. A sealing material characterized by:

8. The metal member is made of a magnetic material. The sealing material according to claim 7 .

9. The fluorine-based resin contains a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer resin. The sealing material according to claim 7 or 8.

10. The core material is made of silicone rubber The sealing material according to claim 7 or 8.

11. The line load at 25% compression is 3.0 N / mm or less The sealing material according to claim 7 or 8.

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