Method for manufacturing a sealing material and sealing 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 Art

[0002] A sealing material in which an annular core material is coated with a fluororesin is known. For example, Patent Document 1 discloses an O-ring in which an annular core material of heat-resistant rubber is coated with a coating of a fluororesin.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] To coat an annular core material with a fluororesin, there is a method of coating a string-shaped core material with a fluororesin and joining both ends.

[0005] To join the connection part, a heating device is generally used. However, since the connection part of an annular sealing material (for example, an O-ring) is relatively small, there is a problem that it cannot be heated efficiently, for example, by a high-temperature press.

[0006] The present invention has been made in view of such points, and an object thereof is to be able to efficiently heat and join both ends of a string-shaped rubber constituting a sealing material.

Means for Solving the Problems

[0007] In order to achieve the above object, in this invention, only the connection part of the string-shaped rubber and its periphery are heated and joined.

[0008] Specifically, in the first invention, Prepare a string-like rubber of a predetermined length, covered with a fluororesin with a thickness of 0.20 mm or less. The joining surfaces of the string-shaped rubber are joined with metal members provided at least at both ends, At least the outer circumference of the bonding surface of the string-like rubber is covered with a fluororesin film made of the same material as the fluororesin, The connection portion covered with the aforementioned fluororesin film and the area surrounding the connection portion are placed near the high-frequency coil. The metal component is heated by a high-frequency coil to melt the fluororesin film and form a fluororesin coating. The system is designed to cool and then extract the annular sealing material.

[0009] According to the above configuration, at least the metal component included in the connection part of the string-shaped rubber is heated by the high-frequency coil, causing the fluororesin film to melt. This eliminates the need for a mold and allows the connection part to be placed as close to the high-frequency coil as possible. Furthermore, since the area heated by high-frequency induction is limited, the range of the effects of heating is limited compared to when the entire structure is heated. As a result, a high-quality sealing material can be obtained. In addition, because the thickness of the coating layer formed of fluororesin covering the string-shaped rubber is 0.20 mm or less, it is more easily deformed than coatings with a thickness greater than 0.20 mm, resulting in a sealing material that can be installed without requiring a large tightening force. The metal component may be embedded in both ends of the string-shaped rubber beforehand, or it may be embedded during connection. "Nearby" means as close as possible to the range reached by the magnetic force of the high-frequency coil 22. In other words, the connection part does not necessarily have to be placed inside the high-frequency coil; it may be placed outside the coil, within the range reached by the magnetic force of the high-frequency coil 22.

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

[0011] With the above configuration, since no mold is required, the connection part can be placed inside the high-frequency coil, allowing for more efficient high-frequency induction heating.

[0012] In the third invention, in the first or second invention, the metal member is made of a metal rod or a metal pipe having the same outer diameter as the string-like rubber, and both ends of the string-like rubber are connected by the metal member.

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

[0014] In the fourth invention, in the first or second invention, the metal member is composed of a metal core wire embedded in the center of the string-like rubber in advance.

[0015] According to the above configuration, a metal member can be arranged at the connection portion of the string-like rubber only by embedding a metal core wire during the molding of the string-like rubber.

[0016] In the fifth invention, in the first or second invention, the metal member is composed of embedded metal pins so as to connect both ends of the string-like rubber.

[0017] <00​​​​​​​​​​​​​​​​​​​​​ The thickness of the coating layer is 0.2 mm or less.

[0021] According to the above configuration, at least the metal member included in the connecting portion of the string-like rubber is heated by the high-frequency coil, so that the fluororesin film melts, eliminating the need for a mold and allowing the connecting portion to be brought as close as possible to the high-frequency coil. And since the portion to be heated by high-frequency induction heating is limited, the range of the influence by heating is limited compared with the case of heating the whole. For this reason, a high-quality sealing material can be obtained. Further, since the thickness of the coating layer formed of a fluororesin for coating the string-like rubber is 0.20 mm or less, it is easier to deform than those having a coating layer thickness larger than 0.20 mm, and a sealing material that can be attached without requiring a large tightening force can be obtained.

[0022] In the eighth invention, in the seventh invention, The metal member is formed of a magnetic material.

[0023] According to the above configuration, since the metal member made of a magnetic material can be efficiently heated by the high-frequency coil, a sealing material with good quality and less influence by heating can be obtained.

[0024] In the ninth invention, in the seventh or eighth invention, The fluororesin includes a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer resin.

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

[0026] In the tenth invention, in any one of the seventh to ninth inventions, The core material is formed of silicone rubber.

[0027] According to the above configuration, since the sealing material has appropriate softness, it is easy to ensure the sealing performance without applying a large tightening force.

[0028] In the 11th invention, in any one of the 7th to 10th inventions, The line load at 25% compression is 3.0 N / mm or less.

[0029] According to the above configuration, a highly marketable sealing material covered with a fluororesin that does not require a large tightening force during installation can be obtained. 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, that is, the sum of the inner diameter and thickness multiplied by pi (π). [Effects of the Invention]

[0030] As described above, according to the present invention, it is possible to efficiently join both ends of a string-shaped rubber while suppressing the effects of heating during joining, thereby obtaining a high-quality sealing material. [Brief explanation of the drawing]

[0031] [Figure 1] This is a cross-sectional view showing an O-ring that is the target of manufacture according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view showing a magnified view of the connection point. [Figure 3] This is a cross-sectional view showing an enlarged view of the connection portion related to Modified Example 1. [Figure 4] This is a cross-sectional view showing an enlarged view of the connection portion related to Modified Example 2. [Figure 5] This is a perspective view showing a heating apparatus related to a method for manufacturing a sealing material according to an embodiment of the present invention. [Figure 6] This flowchart shows a method for manufacturing a sealing material according to an embodiment of the present invention. [Modes for carrying out the invention]

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

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

[0034] The O-ring 10 according to this embodiment comprises an annular core material 11 (string-shaped rubber) and a coating layer 12 covering the core material 11. The coating layer 12 is made of a fluororesin. For this reason, the O-ring 10 can be suitably used 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 embodiment of the O-ring 10, the thickness of the coating layer 12 made of fluororesin that covers the core material 11 is 0.20 mm or less, so it can be installed without requiring a large tightening force. The inventors investigated the reason why a large tightening force is required when installing the O-ring 10 in which the core material 11 is covered with a coating layer 12 of fluororesin, and as a result they focused on the fact that a large repulsive force is generated in the O-ring 10 when compressed, and came up with the idea of ​​controlling this repulsive force by the thickness of the coating layer 12.

[0036] The core material 11 is preferably formed of crosslinked rubber. Examples of rubber used to form the core material 11 include silicone rubber, nitrile rubber, hydrogenated nitrile rubber, fluororubber, ethylene propylene copolymer rubber, ethylene propylene diene terpolymer rubber, and acrylic rubber. From the viewpoint of not requiring a large tightening force during installation, silicone rubber is preferred among these. From the same viewpoint, the hardness of the rubber forming the core material 11 is preferably A40 to A50, and more preferably A43 to A47. This hardness is measured using a Type A durometer based on JIS K6253-3:2023 for the core material 11 before coating with the coating layer 12.

[0037] Examples of fluororesins 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 fluororesin that forms the coating layer 12 preferably contains one or more of these, and it is preferable to include PFA resin from the viewpoint of having 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 for covering 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 the coating layer 12 to the diameter of the 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 the coating layer 12 to the diameter of the O-ring 10 is preferably 0.5% or more, more preferably 1% or more, from the viewpoint of processability for coating the core material 11 with the fluororesin coating layer 12.

[0040] The hardness of the O-ring 10 according to this embodiment is preferably A60 to A80, and more preferably A65 to A77, from the viewpoint of not requiring a large tightening force during installation. This hardness is also measured using 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 linear load of the O-ring 10 when compressed by 25% according to this embodiment is preferably 3.0 N / mm or less, and more preferably 2.0 N / mm or less, from the viewpoint of not requiring a large tightening force during installation. This linear load when compressed by 25% is calculated by dividing the load required to compress the O-ring 10 by 25% in the thickness direction by the average circumference, that is, the sum of the inner diameter and thickness multiplied by pi (π).

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

[0043] First, in the preparation process, a string-like core material 11 is manufactured. The rubber string-like core material 11 can be manufactured, for example, by extrusion molding.

[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 fluororesin coating layer 12 along its length by a so-called coated extrusion molding method, thereby producing a long string-shaped rubber 10'.

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

[0046] Then, an O-ring 10 is manufactured by cutting a predetermined length from the recovered string-like rubber 10' and joining its ends to form a ring. The joining method will be described in detail below.

[0047] As described above, prepare a string-shaped rubber 10' of a predetermined length covered with a fluororesin coating layer 12 having a thickness of 0.20 mm or less.

[0048] Next, in the metal member placement process, as shown in Figure 2, a metal member 16 consisting of a metal rod or metal pipe with the same outer diameter as the string-shaped rubber 10' is placed between the joining surfaces of the string-shaped rubber 10'. The metal rod or metal pipe is made of a magnetic material such as iron or nickel. However, as shown in Figures 3 and 4 described later, the composition of the metal member is not limited to this.

[0049] In this case, for example, a two-part liquid silicone rubber is applied as an adhesive between the string-like rubber 10' and the metal member 16. The adhesive is not limited to this.

[0050] Next, in the fluororesin film winding process shown in step S02 of Figure 6, with the metal member 16 joined, the connecting 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 for example, it can be the same thickness as the coating layer 12. Even if the fluororesin film 15 becomes too thick, it can be ground down after molding, so its thickness can be set to be thicker.

[0051] Next, a connection heating process is performed. In step S03, as shown in Figure 5, the connection part 14 is placed inside the high-frequency coil 22. At this time, since it is not necessary to cover the connection part 14 with a mold, the annular string-shaped rubber 10' can be passed through the gaps between the windings of the high-frequency coil 22. For example, if the gaps between the windings of the high-frequency coil 22 are 5 mm, the string-shaped rubber 10' with a diameter of 3 mm can be passed through without difficulty. If the gaps between the windings of the high-frequency coil 22 are small, the connection part may be placed on the outside of the windings of the high-frequency coil 22, as close as possible to allow for efficient heating.

[0052] Next, in step S04, the connection portion 14 is coated with fluororesin by high-frequency induction heating. For example, only the connection portion 14 and the area around the connection portion 14 covered with the fluororesin film 15 are heated by high-frequency heating using a heating device 20 for 2 minutes, raising the temperature from room temperature to 300°C, and then held for 1 minute. Here, it is not necessary to heat the entire string-shaped rubber 10', so it is not necessary to heat the already coated coating layer 12 over a wide area, and the quality is less likely to deteriorate.

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

[0054] Next, in step S06, the annular O-ring 10 is obtained by removing it from the high-frequency coil 22.

[0055] In some cases, if the fluororesin film 15 portion protrudes more than other outer surfaces, a finishing process such as polishing is performed to ensure that the entire surface is smooth and free of irregularities.

[0056] In this embodiment, since the fluororesin film 15 melts when the metal member 16 included in the connection portion 14 of the string-shaped rubber 10' is heated by the high-frequency coil 22, a mold is not required, and the connection portion 14 can be brought as close to the high-frequency coil 22 as possible. Furthermore, since the portion heated by high-frequency induction is limited, the range of the effect of heating is limited compared to when the entire structure is heated. As a result, a high-quality O-ring 10 can be obtained. In addition, because the thickness of the coating layer 12 formed of fluororesin covering the string-shaped rubber 10' is 0.20 mm or less, it is more easily deformed than those with a coating layer thickness greater than 0.20 mm, and an O-ring 10 that can be installed without requiring a large tightening force can be obtained.

[0057] Furthermore, the high-frequency coil 22 efficiently heats the metal component 16 made of magnetic material, resulting in a high-quality O-ring 10 with minimal effects from heating.

[0058] In this embodiment, by forming the string-shaped rubber 10' from silicone rubber, an O-ring 10 is obtained that has appropriate softness, making it easy to ensure sealing performance without applying a large tightening force.

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

[0060] In this embodiment, the O-ring 10 has a linear 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, it is possible to efficiently join both ends of the string-shaped rubber 10' while suppressing the effects of heating during joining, thereby obtaining a high-quality O-ring 10.

[0062] -Experimental Variation 1- Figure 3 shows a connecting portion 14' according to a modified example 1 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 reference numerals are used for parts that are the same as in Figures 1 and 2, and their detailed descriptions are omitted.

[0063] In other words, in this modified example, the metal member 16' consists of a metal core wire embedded in the center of the string-shaped rubber 10' during extrusion molding. For example, if the diameter of the string-shaped rubber 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 modified example, the metal member 16' is pre-embedded inside the string-like rubber 10', making the joining process easier. Furthermore, 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- Figure 4 shows a connecting portion 14'' according to a modified example 2 of the present invention, which differs from the above embodiment in that the configuration of the metal member 16'' is different.

[0066] In other words, in this modified example, the metal member 16'' consists of a single metal positioning pin. In this modified example as well, the metal member 16'' is preferably made of a flexible magnetic material. It may be pre-bent 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] Then, when joining the string-like rubber 10', insert it into the center of the core material 11 at one end, apply adhesive to the joining surface before or after, and insert the other end of the metal member 16'' into the center of the core material 11 at the other end. After that, cover the connecting part 14'' with a fluororesin film 15. Since the metal member 16'' is located in the center of both ends during bonding, the bonding work is easy. For example, if the diameter of the string-like rubber 10' is 3 mm, the metal positioning pin will have a diameter of 1 mm, but it is not limited to this.

[0068] In this modified example, the joining process is simplified because metal members 16'' can be embedded in both ends of the core material 11 when joining the string-shaped rubber 10'.

[0069] (Other embodiments) The present invention may also have the following configuration in the above embodiment.

[0070] In other words, although the O-ring 10 was shown as an example of a sealing material in the above embodiment, it is not limited to this, and any 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 coating layer 12 by a coating extrusion molding method. However, the invention is not limited to this, and for example, the coating 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 it is coated with the coating layer 12 may be subjected to a surface treatment to improve adhesion with the fluororesin coating layer 12. By performing such a surface treatment on the surface of the string-shaped core material 11 before it is 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 with a thickness of 0.20 mm or less can be suppressed. Examples of such surface treatments include primer treatment, Itro treatment, plasma treatment, etc.

[0073] In the manufacturing method of the O-ring 10 according to the embodiment, plasma treatment may be applied to the surface of the molten fluororesin R that is intended to come into contact with the string-shaped core material 11 before coating the string-shaped core material 11, in order to improve adhesion with the string-shaped core material 11. As a result of applying plasma treatment to the contact surface of the coating layer 12 with the core material 11, the adhesion of the fluororesin coating layer 12 to the core material 11 can be improved, and the occurrence of wrinkles on the surface of the coating layer 12 can be suppressed.

[0074] The embodiments described above 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' String-shaped rubber 10 O-rings (sealants) 11 Core material 12 Covering layer 14,14',14'' connection 15 Fluororesin film 16,16',16'' metal parts 20 Heating device 22 High-frequency coil

Claims

1. Prepare a string-like rubber of a predetermined length, covered with a fluororesin with a thickness of 0.20 mm or less. The joining surfaces of the string-shaped rubber are joined with metal members provided at least at both ends, At least the outer circumference of the bonding surface of the string-shaped rubber is covered with a fluororesin film made of the same material as the fluororesin, The connection portion covered with the aforementioned fluororesin film and the area surrounding the connection portion are placed near the high-frequency coil. The metal component is heated by a high-frequency coil to melt the fluororesin film and form a fluororesin coating. Cool and remove the annular sealant. A method for manufacturing a sealing material characterized by the following:

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

3. The aforementioned metal member consists of a metal rod or metal pipe having the same outer diameter as the aforementioned string-like rubber. The ends of the string-like rubber are connected by the aforementioned metal member. A method for manufacturing a sealing material according to claim 1 or 2, characterized by the above.

4. The aforementioned metal member consists of a metal core wire that has been pre-embedded in the center of the string-shaped rubber. A method for manufacturing a sealing material according to claim 1 or 2, characterized by the above.

5. The aforementioned metal member consists of embedded metal pins that connect both ends of the string-like rubber. A method for manufacturing a sealing material according to claim 1 or 2, characterized by the above.

6. The aforementioned metal member is formed from a magnetic material. A method for manufacturing a sealing material according to claim 1 or 2, characterized by the above.

7. A ring-shaped core material, A coating layer made of a fluororesin covering the core material, It comprises 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. The aforementioned metal member is formed of a magnetic material. A sealing material characterized by the following features.

8. The fluorine-based resin includes a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer resin. The sealing material according to feature 7.

9. An annular core material, A coating layer made of a fluororesin covering the core material, It comprises 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. The core material is formed of silicone rubber. A sealing material characterized by the following features.

10. An annular core material, A coating layer made of a fluororesin covering the core material, It comprises 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. The line load at 25% compression is 3.0 N / mm or less. A sealing material characterized by the following features.

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