JP2019065307A - Sealing material and manufacturing method thereof - Google Patents

Abstract

To provide a sealant having excellent plasma resistance.SOLUTION: A sealant is formed of a rubber composition in which a hydrogen-containing fluorine rubber is crosslinked with a heat crosslinker, and after a carbon-hydrogen bond of the hydrogen-containing fluorine rubber is cut, the remaining carbon is bound to a hydrogen site protectant.SELECTED DRAWING: None

Description

  The present invention relates to a sealing material and a method of manufacturing the same.

  Silicone rubber is known as a rubber component having high resistance to oxygen plasma but low resistance to fluorine plasma. Vinylidene fluoride-based fluororubber (hereinafter referred to as "FKM") is known as a rubber component having high resistance to fluorine plasma, but low resistance to oxygen plasma. Tetrafluoroethylene-perfluorovinyl ether-based fluororubber (hereinafter referred to as "FFKM") is known as an expensive rubber component as compared to silicone rubber and FKM, although both of oxygen plasma resistance and fluorine plasma resistance are high. ing. Therefore, it has been proposed to mix and use these rubber components. For example, Patent Document 1 discloses that a silicone rubber and an FFKM are mixed and used, and that an FKM and an FFKM are mixed and used. Patent Document 2 discloses that FKM and FFKM are mixed and used. Patent Document 3 discloses mixing and using silicone rubber and FKM.

  Further, as a technique for improving plasma resistance, Patent Documents 4 and 5 disclose that a reactive fluorine-based compound is added to FKM. Furthermore, in Patent Document 6, in addition to adding an excess cross-linking coagent to FKM and heating the FKM to crosslink with the cross-linking coagent, it is irradiated with radiation and further cross-linked with an excess cross-linking coagent, It is disclosed that the physical properties of rubber itself are improved by increasing the crosslink density accordingly.

Patent No. 4778782 Patent No. 4628814 gazette JP 2001-348462 A Patent No. 4675907 Patent No. 5189728 gazette Patent No. 4381087

  An object of the present invention is to provide a sealing material excellent in plasma resistance.

  The present invention relates to a hydrogen-containing fluoro rubber, a thermal cross-linking agent for crosslinking the hydrogen-containing fluoro rubber when heated to a predetermined temperature, and carbon-hydrogen of the hydrogen-containing fluoro rubber when irradiated with radiation. The hydrogen site protecting agent which bonds to a radical of carbon which is generated by breaking the bond, and the hydrogen containing fluorine is interposed between molecules of the hydrogen containing fluorine rubber when the hydrogen containing fluorine rubber is crosslinked by the thermal crosslinking agent. Manufactured using an uncrosslinked rubber composition which contains a crosslinking assistant to be bonded to a fluororubber, and the ratio of the content of the crosslinking assistant to the content of the thermal crosslinking agent is 2.0 or more and 3.0 or less The hydrogen site protecting agent is carbon after the hydrogen-containing fluororubber is crosslinked by the thermal crosslinking agent and the carbon-hydrogen bond of the hydrogen-containing fluororubber is cut. It is formed of a combined rubber composition.

  The present invention relates to a hydrogen-containing fluoro rubber, a thermal cross-linking agent for crosslinking the hydrogen-containing fluoro rubber when heated to a predetermined temperature, and carbon-hydrogen of the hydrogen-containing fluoro rubber when irradiated with radiation. The hydrogen site protecting agent which bonds to a radical of carbon which is generated by breaking the bond, and the hydrogen containing fluorine is interposed between molecules of the hydrogen containing fluorine rubber when the hydrogen containing fluorine rubber is crosslinked by the thermal crosslinking agent. The uncrosslinked rubber composition which contains a crosslinking assistant to be bonded to a fluororubber, and the ratio of the content of the crosslinking assistant to the content of the thermal crosslinking agent is 2.0 or more and 3.0 or less, at a predetermined temperature The hydrogen-containing fluororubber is heated by heating to crosslink it with the thermal crosslinking agent, and then irradiated with radiation to break the carbon-hydrogen bond of the hydrogen-containing fluororubber, thereby forming a radical of carbon generated by the radical. Method for producing a sealing material which binds the protective agent.

  According to the present invention, the hydrogen site of the hydrogen-containing fluororubber, which is a site with low plasma resistance, breaks the bond between carbon and hydrogen when irradiated with radiation to generate a carbon radical, and the carbon radical Since the hydrogen site protecting agent is protected by bonding to the above, excellent plasma resistance can be obtained.

  Hereinafter, the embodiment will be described in detail.

  The non-crosslinked rubber composition according to the embodiment is a rubber product, particularly, for example, a sealing material such as an O-ring excellent in plasma resistance used in an apparatus using plasma such as a semiconductor etching apparatus or plasma CVD apparatus. And a hydrogen-containing fluoro rubber as a rubber component, a thermal crosslinking agent, and a hydrogen site protecting agent.

  The “hydrogen-containing fluororubber” in the present application is a fluororubber containing carbon in which hydrogen is bonded to the main chain of a polymer. The hydrogen-containing fluororubber preferably contains, for example, vinylidene fluoride (VDF), propylene (Pr), ethylene (E) or the like as a monomer.

  As the hydrogen-containing fluororubber, for example, a polymer of vinylidene fluoride (VDF) (PVDF), a copolymer of vinylidene fluoride (VDF) and hexafluoropropylene (HFP), vinylidene fluoride (VDF) and hexafluorocarbon Copolymer of propylene (HFP) and tetrafluoroethylene (TFE), copolymer of tetrafluoroethylene (TFE) and propylene (Pr) (FEP), vinylidene fluoride (VDF) and propylene (Pr) and tetra Copolymer with fluoroethylene (TFE), copolymer with ethylene (E) and tetrafluoroethylene (TFE) (ETFE), ethylene (E) with tetrafluoroethylene (TFE) and perfluoromethylvinylether (PMVE) Copolymer with vinylidene fluoride Copolymer (VDF) and tetrafluoroethylene (TFE) and perfluoromethylvinylether (PMVE), copolymer of vinylidene fluoride and (VDF) and perfluoromethylvinylether (PMVE) and the like. As the hydrogen-containing fluororubber, it is preferable to use one or two or more of these.

  The thermal crosslinking agent is a compound that crosslinks the hydrogen-containing fluororubber when heated to a predetermined temperature. Examples of the thermal crosslinking agent include peroxides, polyols, polyamines, triazines and the like. As the thermal crosslinking agent, it is preferable to use a peroxide of these from the viewpoint that it is not necessary to use an acid acceptor that causes generation of particles in a plasma atmosphere. As the peroxide, for example, 1,1-bis (t-butylperoxy) -3,5,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroperoxide, di-t-butylperoxide Oxide, t-butylcumyl peroxide, dicumyl peroxide, α, α-bis (t-butylperoxy) -p-diisopropylbenzene, 2,5-dimethyl-2,5-di (t-butylperoxy) Hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexyne-3, benzoyl peroxide, t-butylperoxybenzene, t-butylperoxymaleic acid, t-butylperoxyisopropyl Carbonate, t-butylperoxybenzoate and the like can be mentioned. It is preferable to use 1 type, or 2 or more types in these of a thermal crosslinking agent, and it is more preferable to use 2, 5- dimethyl- 2, 5- di (t- butylperoxy) hexane. The content (A) of the thermal crosslinking agent is preferably 0.5 parts by mass or more with respect to 100 parts by mass of the hydrogen-containing fluororubber from the viewpoint of promoting crosslinking sufficiently and obtaining good physical properties as a sealing material. It is 5 parts by mass or less, more preferably 0.5 parts by mass or more and 2.0 parts by mass or less.

  The hydrogen site protecting agent is a compound which bonds to a radical of carbon which is generated by breaking a carbon-hydrogen bond of a hydrogen-containing fluororubber when irradiated with radiation. Here, the “hydrogen site” in the present application refers to a carbon-bonded portion in the main chain of the polymer constituting the hydrogen-containing fluororubber. Specifically, for example, a CH binding site in the VDF component. The hydrogen site protecting agent is a compound of a perfluoro skeleton having an alkenyl group bonded to a carbon radical of hydrogen-containing fluororubber in the molecule, and / or an alkenyl group bonded to a carbon radical of hydrogen-containing fluororubber in the molecule It is preferable to include a compound having a siloxane skeleton having

  As an alkenyl group, a vinyl group, an allyl group, a butenyl group, pentenyl group, a hexenyl group, heptenyl group etc. are mentioned, for example. The alkenyl group is preferably a vinyl group among them.

  Examples of the compound having a perfluoro skeleton having an alkenyl group in the molecule include a compound having a perfluoropolyether structure, a compound having a perfluoroalkylene structure, and the like.

  Examples of the siloxane skeleton compound having an alkenyl group in the molecule include a polymer of methylvinylsiloxane, a polymer of dimethylsiloxane, a copolymer of dimethylsiloxane and methylvinylsiloxane, dimethylsiloxane, methylvinylsiloxane and methylphenyl Copolymers with siloxane and the like can be mentioned. Other examples include organopolysiloxanes containing alkenyl groups in the molecule, which are liquid silicone rubbers of addition polymerization.

  The compound of the perfluoro skeleton or the compound of the siloxane skeleton preferably has two or more alkenyl groups in the molecule. Two or more alkenyl groups may be the same or different. If the hydrogen site protecting agent has two or more alkenyl groups in the molecule, it can function as a crosslinking aid for crosslinking hydrogen-containing fluororubbers in addition to the protection of hydrogen sites.

  As the hydrogen site protecting agent, it is preferable to use one or more of these, and it is more preferable to use a compound having a perfluoropolyether structure having an alkenyl group in the molecule, and it is preferable to use an alkenyl group in the molecule. It is more preferable to use a compound having a perfluoropolyether structure having more than one.

  The hydrogen site protective agent is preferably a one-pack liquid material. In that case, the viscosity at 23 ° C. of the hydrogen site protecting agent is preferably 30 Pa · s or more and 100 Pa · s or less, more preferably 40 Pa · s or more and 70 Pa · s or less in the case of a compound having a perfluoro skeleton. In the case of a compound, it is preferably 100 Pa · s or more and 150 Pa · s or less, more preferably 120 Pa · s or more and 140 Pa · s or less.

  The content (B) of the hydrogen site protecting agent is preferably 1 part by mass or more and 20 parts by mass or less, more preferably 5 parts by mass or more, with respect to 100 parts by mass of the hydrogen-containing fluororubber, from the viewpoint of enhancing plasma resistance. It is below a mass part. The content (B) of the hydrogen site protective agent is preferably greater than the content (A) of the thermal crosslinking agent from the viewpoint of enhancing the plasma resistance. The ratio (B / A) of the content (B) of the hydrogen site protecting agent to the content (A) of the thermal crosslinking agent is preferably 2.5 or more and 30 or less, more preferably 5 or more from the viewpoint of enhancing plasma resistance. .0 or more and 10 or less.

  The uncrosslinked rubber composition according to the embodiment may further contain a crosslinking aid. The crosslinking aid is a compound which bonds to the hydrogen-containing fluororubber so as to be interposed between molecules of the hydrogen-containing fluororubber when the hydrogen-containing fluororubber is crosslinked by the thermal crosslinking agent.

  Examples of crosslinking assistants include triallyl cyanurate, trimethallyl isocyanurate, triallyl isocyanurate, triacrylic formal, triallyl trimellitate, N, N'-m-phenylene bismaleimide, dipropargyl terephthalate, diallyl. Phthalate, tetraallyl terephthalate amide, triallyl phosphate, bismaleimide, fluorinated triallylisocyanurate (1,3,5-tris (2,3,3-trifluoro-2-propenyl) -1,3,5-triazine -2,4,6-trione), tris (diallylamine) -S-triazine, triallyl phosphite, N, N-diallylacrylamide, 1,6-divinyldodecafluorohexane, hexaallylphosphoramide, N, N, N ', N'-tetraallyl phthalate Amide, N, N, N ', N'-tetraallylmalonamide, trivinyl isocyanurate, 2,4,6-trivinylmethyltrisiloxane, tri (5-norbornene-2-methylene) cyanurate, triallyl phosphite Etc. It is preferable to use 1 type, or 2 or more types of these crosslinking adjuvants, and it is more preferable to use triallyl isocyanurate.

  The content (C) of the crosslinking assistant is preferably 1 to 10 parts by mass, more preferably 2 to 1 part by mass from the viewpoint of obtaining good physical properties as a sealing material with respect to 100 parts by mass of the hydrogen-containing fluororubber. It is 5 parts by mass or less. The content (C) of the crosslinking assistant is preferably larger than the content (A) of the thermal crosslinking agent from the viewpoint of enhancing the plasma resistance. The ratio (C / A) of the content (C) of the crosslinking aid to the content (A) of the thermal crosslinking agent is that the crosslinking aid is reacted without excess and deficiency to obtain good physical properties as a sealing material, Preferably it is 1.0 or more and less than 4.0, More preferably, it is 2.0 or more and 3.0 or less.

  If the content of the uncrosslinked rubber composition according to the embodiment is less than the content of the hydrogen-containing fluororubber, the non-crosslinked rubber composition may be a silicone rubber as a rubber component other than the hydrogen-containing fluororubber or a copolymer of tetrafluoroethylene and praurovinylether. May contain a fluororubber which does not contain carbon bonded to hydrogen in the main chain of the polymer. The uncrosslinked rubber composition according to the embodiment may contain a reinforcing material such as carbon black or silica, a plasticizer, a processing aid, a vulcanization accelerator, an antioxidant, etc. depending on the rubber product to be produced. . However, when used in the production of rubber products where generation of particles in a plasma atmosphere is a problem, the content of powdery inorganic fillers such as carbon black, silica, metal oxides, etc. The amount is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, and most preferably 0 parts by mass with respect to 100 parts by mass of the fluororubber. In the case of a hydrogen-containing fluorocarbon resin powder such as PVDF or ETFE, the powdery organic filler can be expected to improve physical properties by crosslinking with a hydrogen-containing fluororubber at the time of irradiation with radiation described later.

  The uncrosslinked rubber composition according to the embodiment can be manufactured using an open rubber kneader such as an open roll or a closed rubber kneader such as a kneader.

  Next, a method of producing a rubber product using the uncrosslinked rubber composition according to the embodiment will be described.

  In the method for producing a rubber product, first, a predetermined amount of the non-crosslinked rubber composition according to the embodiment is filled in the cavity of the preheated mold, and then clamped, and in that state, a predetermined molding temperature and a predetermined The molding pressure is maintained for a predetermined molding time. At this time, the uncrosslinked rubber composition according to the embodiment is molded into the shape of a cavity, and the hydrogen-containing fluorocarbon rubber is crosslinked by the thermal crosslinking agent to lose its plasticity. This molding may be press molding or may be injection molding. The molding temperature is, for example, 150 ° C. or more and 180 ° C. or less. The molding pressure is, for example, 0.1 MPa or more and 25 MPa or less. The molding time is, for example, 3 minutes or more and 20 minutes or less.

  Then, the mold is opened, the molded product is taken out from the inside and cooled, and then the molded product is irradiated with radiation. At this time, radiation is applied to cut the carbon-hydrogen bond at the hydrogen site of the hydrogen-containing fluororubber to generate a carbon radical, and the hydrogen site protecting agent is bonded to the carbon radical. Examples of radiation include α rays, β rays, γ rays, electron beams, ions and the like. As the radiation, it is preferable to use an electron beam or γ ray among them. The irradiation dose of radiation is preferably 10 kGy or more and 100 kGy or less, more preferably 30 kGy or more and 80 kGy or less, from the viewpoint of enhancing plasma resistance.

  From the above, from the uncrosslinked rubber composition according to the embodiment, the hydrogen-containing fluororubber is crosslinked by the thermal crosslinking agent, and the hydrogen site protecting agent on carbon after the carbon-hydrogen bond of the hydrogen-containing fluororubber is cut A rubber product is obtained which is formed of a rubber composition in which

  According to the uncrosslinked rubber composition according to the embodiment of the above configuration, the hydrogen site of the hydrogen-containing fluororubber, which is a portion with low plasma resistance, is broken in the carbon-hydrogen bond when it is irradiated with radiation. The carbon site is protected by bonding the hydrogen site protecting agent to the carbon radical, so that a rubber product having excellent plasma resistance can be produced by using this carbon site. In addition, since the hydrogen site protecting agent reacts with the hydrogen-containing fluororubber, bleed out does not become a problem.

(Rubber composition)
The rubber compositions of Examples 1 to 2 and Comparative Examples 1 to 3 below were prepared. Each configuration is also shown in Table 1.

Example 1
A peroxide containing a thermal crosslinking agent based on 100 parts by mass of the hydrogen-containing fluororubber contained in a hydrogen-containing fluororubber (made by Daiel G912 Daikin Industries, Ltd.) consisting of a copolymer of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene 1.5 parts by mass of 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (Perhexa 25B, manufactured by Nippon Oil and Fats Co., Ltd.) which is 10 parts by mass of a compound having a perfluoro group having a vinyl group (SIFEL 3590-N, manufactured by Shin-Etsu Chemical Co., Ltd., viscosity (23 ° C.): 50 Pa · s), and triallyl isocyanurate as a crosslinking assistant (TYK, manufactured by Nippon Kasei Co., Ltd.) An uncrosslinked rubber composition was prepared by blending and kneading 4 parts by mass. Subsequently, the uncrosslinked rubber composition is press-formed at a molding temperature of 165 ° C., a molding pressure of 5 MPa, and a molding time of 15 minutes, and then heat treated at a heating temperature of 200 ° C. and a heating time of 4 hours to form a sheet-like rubber composition. I got Then, the sheet-like rubber composition was irradiated with γ-rays of an irradiation dose of 30 kGy. The sheet-like rubber composition irradiated with this γ-ray was referred to as Example 1.

Example 2
As a hydrogen site protecting agent, a compound having a vinyl group in its molecule (KE-1830, Shin-Etsu Chemical Co., Ltd., viscosity (23 ° C.): 130 Pa · s), which is a one-pack type liquid material A sheet-like rubber composition produced in the same manner as in Example 1 except for the above was taken as Example 2.

Comparative Example 1
A sheet-like rubber composition produced in the same manner as Example 1 except that the hydrogen site protective agent was not blended was taken as Comparative Example 1.

Comparative Example 2
The same as Example 1 except that 20 parts by mass of silicone rubber (KE-941-U manufactured by Shin-Etsu Chemical Co., Ltd.) was compounded with 100 parts by mass of hydrogen-containing fluororubber without compounding a hydrogen site protective agent. The sheet-like rubber composition produced was used as Comparative Example 2.

Comparative Example 3
Except that no hydrogen site protecting agent is blended, 20 parts by mass of a copolymer of tetrafluoroethylene and perfluorovinyl ether (FFKM: AFLASP Remium PM1100 manufactured by Asahi Glass Co., Ltd.) is blended with 100 parts by mass of hydrogen-containing fluororubber A sheet-like rubber composition produced in the same manner as in Example 1 was taken as Comparative Example 3.

(Test method)
<Plasma resistance>
For each of Examples 1 to 2 and Comparative Examples 1 to 3, an O ₂ plasma irradiation test and a CF ₄ plasma irradiation test are performed using a microwave plasma generator at an elongation rate of 10%, and weight loss, presence or absence of cracks And the presence or absence of generation of particles were examined. In the test, O ₂ and CF ₄ were used as reaction gases, their flow ratio was 50: 1 in the O ₂ plasma irradiation test, and their flow ratio was 1: 50 in the CF ₄ plasma irradiation test. The reaction pressure was 100 Pa and the plasma irradiation time was 60 minutes.

<Tensile characteristics>
A tensile test is performed based on JIS K6251 for each of Examples 1 to 2 and Comparative Examples 1 to 3, and 100% modulus (M ₁₀₀ : tensile stress at 100% elongation), tensile strength (TB), and cutting. The time elongation (EB) was measured.

<Compression set>
For each of Examples 1 to 2 and Comparative Examples 1 to 3, measurement of compression set was performed at a test time of 72 hours and a test temperature of 200 ° C. based on JIS K6262: 2013.

(Test results)
The test results are shown in Table 1.

According to Table 1, it can be seen that Examples 1 and 2 using a hydrogen site protective agent have excellent plasma resistance against both O ₂ plasma and CF ₄ plasma. On the other hand, in Comparative Examples 1 to 3 in which no hydrogen site protective agent is used, although there is no generation of particles with respect to the O ₂ plasma, the mass loss is large (particularly, Comparative Example 1) and cracks are generated. I understand. In addition, for CF ₄ plasma, although Comparative Examples 1 and 3 have excellent plasma resistance, Comparative Example 2 has a large mass loss even though no particle is generated, and a crack is generated. I understand. In addition, about the tensile property and the compression set, the superiority or inferiority between Example 1-2 and Comparative Examples 1-3 was not recognized.

  The present invention is useful in the technical field of a sealing material and a method of manufacturing the same.

Claims (7)

A hydrogen-containing fluororubber, a thermal crosslinking agent for crosslinking the hydrogen-containing fluororubber when heated to a predetermined temperature, and a carbon-hydrogen bond of the hydrogen-containing fluororubber are cut when irradiated with radiation And a hydrogen site protecting agent that bonds to a radical of carbon, and the hydrogen-containing fluororubber is bonded so as to be interposed between molecules of the hydrogen-containing fluororubber when the hydrogen-containing fluororubber is crosslinked by the thermal crosslinking agent A sealing material manufactured using an uncrosslinked rubber composition which contains a crosslinking aid and the ratio of the content of the crosslinking aid to the content of the thermal crosslinking agent is 2.0 or more and 3.0 or less There,
The hydrogen-containing fluororubber is formed by a rubber composition in which the hydrogen site protective agent is bonded to carbon after being crosslinked by the thermal crosslinking agent and at the same time the carbon-hydrogen bond of the hydrogen-containing fluororubber is cut. Sealing material. In the sealing material according to claim 1,
The hydrogen site protecting agent may be a compound of a perfluoro skeleton having an alkenyl group bonded to the carbon radical in the molecule and / or a compound of a siloxane skeleton having an alkenyl group bonded to the carbon radical in the molecule. Containing sealing material. In the sealing material according to claim 2,
The sealing material, wherein the hydrogen site protective agent has two or more alkenyl groups in the molecule. In the sealing material according to any one of claims 1 to 3,
The sealing material wherein the content of the hydrogen site protective agent is 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the hydrogen-containing fluororubber. The sealing material according to any one of claims 1 to 4
The sealing material whose content of an inorganic filler is 5 mass parts or less with respect to 100 mass parts of said hydrogen-containing fluororubber. The sealing material according to any one of claims 1 to 5,
Sealant used in equipment that uses plasma.   A hydrogen-containing fluororubber, a thermal crosslinking agent for crosslinking the hydrogen-containing fluororubber when heated to a predetermined temperature, and a carbon-hydrogen bond of the hydrogen-containing fluororubber are cut when irradiated with radiation And a hydrogen site protecting agent that bonds to a radical of carbon, and the hydrogen-containing fluororubber is bonded so as to be interposed between molecules of the hydrogen-containing fluororubber when the hydrogen-containing fluororubber is crosslinked by the thermal crosslinking agent By heating an uncrosslinked rubber composition containing a crosslinking aid and having a ratio of the content of the crosslinking aid to the content of the thermal crosslinking agent of 2.0 or more and 3.0 or less to a predetermined temperature After the hydrogen-containing fluororubber is crosslinked by the thermal crosslinking agent, the hydrogen site protecting agent is formed of carbon radicals generated by irradiation of radiation to cut the carbon-hydrogen bond of the hydrogen-containing fluororubber. Method for manufacturing a seal material engaged.