Rubber composition, fluorine-containing elastomer and sealing material

Abstract

To provide: a new rubber composition for producing a fluorine-containing elastomer having well-balanced characteristics; and a sealing material including a fluorine-containing elastomer.SOLUTION: A rubber composition is provided which includes (a) crosslinking reactive fluorine rubber, (b) crosslinking reactive perfluoro rubber, (c) a fluorine oligomer having a perfluoro skeleton, and (d) a composition represented by the following expression (d-1). In the formula, A is a single bond, -O-, -S-, a hetero atom-containing group, a linear or branched alkylene group, a cycloalkylene group or an arylene group, and in these groups, R1, R2, R3 and R4 are each independently H, F, an alkyl group, a fluoroalkyl group or an aryl group. At least one of R1, R2 and R3 is a fluorine atom or a group including a fluorine atom. m is an integer of 1 to 5. n is an integer of 1 to 5.SELECTED DRAWING: None

Description

Technical Field

[0001] The disclosure in the present application relates to a sealing material used in a site where plasma resistance is required, a rubber composition for forming the sealing material, and a fluorine-containing elastomer.

Background Art

[0002] Mainly fluorine-containing elastomers are used as the sealing material where plasma resistance is required. While the sealing material is required to have plasma resistance, it is also required to have a predetermined hardness. Patent Document 1 discloses that by using (a) a crosslinkable fluorine rubber or (b) a crosslinkable perfluororubber as a rubber component, and combining it with (c) one or more selected from the group consisting of a reactive compound having a perfluoro skeleton or a siloxane skeleton and a fluorine oligomer, and (d) a compound represented by the following formula (d-1), a sealing material having a predetermined hardness while maintaining plasma resistance can be provided.

Chemical Formula

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when using a fluorine-containing elastomer obtained by crosslinking fluororubber for applications such as sealing materials, it is necessary to achieve well-balanced properties such as hardness, plasma resistance, and tensile strength. Also, industrially, it is necessary to manufacture products homogeneously. However, when the present inventors investigated in more detail the properties of the fluorine-containing elastomer described in Patent Document 1, they newly discovered that the fluorine-containing elastomer described in Patent Document 1 has a problem of a short crack-in time with respect to plasma resistance.

[0005] The disclosure in the present application was made to solve the above problems. As a result of intensive research, the present inventors have found that by crosslinking a rubber composition obtained by combining (a) a crosslinkable fluororubber, (b) a crosslinkable perfluororubber, (c) a fluorine oligomer having a perfluorinated skeleton, and (d) a compound represented by the above formula (d-1), the crack-in time can be prolonged, and a fluorine-containing elastomer having well-balanced properties can be obtained, and it has been newly found that the above problems can be solved.

[0006] That is, the object of the disclosure of the present application is to provide a new rubber composition for producing a fluorine-containing elastomer having well-balanced properties and a sealing material containing the fluorine-containing elastomer.

Means for Solving the Problems

[0007] The disclosure in the present application relates to a rubber composition, a fluorine-containing elastomer, and a sealing material shown below.

[0008] (1) (a) A crosslinkable fluororubber, (b) A crosslinkable perfluororubber, (c) A fluorine oligomer having a perfluorinated skeleton, (d) A compound represented by the following formula (d-1),

Chemical formula

Advantages of the Invention

[0009] By using the rubber composition disclosed in the present application, a fluorine-containing elastomer having well-balanced properties and a sealing material containing the fluorine-containing elastomer can be obtained.

Modes for Carrying Out the Invention

[0010] Hereinafter, the rubber composition, fluorine-containing elastomer, and sealing material disclosed in the present application will be described in detail.

[0011] In this specification, a numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value. Further, in this specification, numerical values, numerical ranges, and qualitative expressions (for example, expressions such as "identical" and "the same") are to be interpreted as indicating numerical values, numerical ranges, and properties including generally acceptable errors in the technical field.

[0012] (Embodiment of the Rubber Composition) The rubber composition according to the embodiment contains (a) a crosslinkable fluororubber, (b) a crosslinkable perfluororubber, (c) a fluorine oligomer having a perfluoroskeleton, and (d) a compound represented by the formula (d-1).

[0013] <Regarding Components (a) and (b)>[ First, the crosslinkable fluororubber as component (a) (hereinafter, may be referred to as "FKM") and the crosslinkable perfluororubber as component (b) (hereinafter, may be referred to as "FFKM") will be described. When FKM and FFKM are grouped together, they may simply be referred to as "fluorine-containing crosslinkable rubber".

[0014] "Crosslinking reactivity" means a fluorine-containing rubber that can be crosslinked by a crosslinking reaction. The fluorine-containing crosslinking-reactive rubber can contain, for example, repeating units derived from a fluorine-containing monomer. The fluorine-containing crosslinking-reactive rubber can contain repeating units derived from one or more fluorine-containing monomers.

[0015] Examples of the fluorine-containing monomer include tetrafluoroethylene (TFE) represented by the following formula (a-1), hexafluoropropylene (HFP) represented by the following formula (a-2), and the like. CF 2 =CF 2 (a-1) CF 2 =CFCF 3 (a-2)

[0016] In addition, examples of the fluorine-containing monomer include, for example, perfluoroolefins having one ethylenic unsaturated bond preferably at the terminal position. Specific examples include perfluoroalkyl vinyl ether (PAVE) represented by the following formula (a-3), perfluorooxyalkyl vinyl ether represented by the following formula (a-4), perfluorovinyl ether represented by the following formula (a-5), and the like.

[0017] CF 2 =CFOR f1 (a-3) (In formula (a-3), R f1 is a perfluoroalkyl having 1 to 6 carbon atoms, such as trifluoromethyl or pentafluoropropyl.)

[0018] CF 2 =CFOR f2 (a-4) (In formula (a-4), R f2 is a perfluorooxyalkyl having 1 to 12 carbon atoms containing one or more ether groups, such as perfluoro-2-propoxypropyl.)

[0019] CF 2 =CFOCF 2 OR f3(a-5) (In formula (a-5), R f3 is a linear or branched perfluoroalkyl having 2 to 6 carbon atoms, a cyclic perfluoroalkyl having 5 or 6 carbon atoms, or a linear or branched perfluorooxyalkyl having 2 to 6 carbon atoms and containing 1 to 3 oxygen atoms.)

[0020] In one embodiment, the perfluorovinyl ether represented by formula (a-5) is represented by the following formula (a-6) or formula (a-7). The perfluorovinyl ether represented by formula (a-6) may be referred to as "MOVE1", and the perfluorovinyl ether represented by formula (a-7) may be referred to as "MOVE2".

[0021] CF 2 =CFOCF 2 OCF 2 CF 3 (a-6) CF 2 =CFOCF 2 OCF 2 CF 2 OCF 3 (a-7) In one embodiment, the fluorine-containing crosslinkable rubber can be a copolymer containing repeating units derived from one or more fluorine-containing monomers selected from the group consisting of formula (a-1) and formula (a-2), and repeating units derived from one or more fluorine-containing monomers (comonomers) selected from the group consisting of formula (a-3) to formula (a-5).

[0022] The composition (molar ratio) of the fluorine-containing monomers used for producing the fluorine-containing crosslinkable rubber is not particularly limited.

[0023] In one embodiment, the fluorine-containing crosslinkable rubber is produced using 50 to 85 mol% of one or more fluorine-containing monomers selected from the group consisting of formula (a-1) and formula (a-2), and 15 to 50 mol% of one or more fluorine-containing monomers selected from the group consisting of formula (a-3) to formula (a-5).

[0024] In one embodiment, the fluorine-containing crosslinkable rubber is produced using 50 to 85 mol% of TFE and 15 to 50 mol% of PAVE.

[0025] In one embodiment, the fluorine-containing crosslinkable rubber is produced using 50 to 85 mol% of TFE and 15 to 50 mol% of MOVE. Here, "MOVE" is one or more selected from the group consisting of MOVE1 and MOVE2.

[0026] In one embodiment, the fluorine-containing crosslinkable rubber contains or does not contain units derived from vinylidene fluoride.

[0027] As used herein, FKM means a rubber containing hydrogen in its chemical structure among the above-mentioned fluorine-containing crosslinkable rubbers. FKM includes, for example, vinylidene fluoride / hexafluoropropylene copolymer (binary FKM), vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene copolymer (ternary FKM), vinylidene fluoride / hexafluoropropylene / perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene / propylene copolymer, hexafluoropropylene / ethylene copolymer, tetrafluoroethylene / ethylene / perfluoroalkyl vinyl ether copolymer, fluorine rubbers (FKM) such as vinylidene fluoride / 2,3,3,3-tetrafluoropropylene, etc., but is not limited thereto.

[0028] As used herein, FFKM means a rubber containing no hydrogen in its chemical structure among the above-mentioned fluorine-containing crosslinkable rubbers. FFKM includes, for example, perfluororubbers such as tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (FFKM), etc., but is not limited thereto.

[0029] FKM is inexpensive and has a certain degree of plasma resistance and heat resistance. When higher plasma resistance is required, it is used in mixture with FFKM. In the rubber composition according to the embodiment, FKM and FFKM are included as essential components. Note that FKM and FFKM are incompatible. Therefore, FKM and FFKM form a phase separation structure such as a sea-island structure or a co-continuous structure according to the blending ratio.

[0030] As described above, FKM contains hydrogen in its chemical structure. On the other hand, FFKM does not contain hydrogen in its chemical structure and contains more fluorine than FKM. Therefore, FFKM is superior to FKM in plasma resistance. Also, FKM and FFKM are not compatible due to the difference in characteristics based on the difference in chemical structure, and form a phase separation structure as described above. The larger the proportion of FFKM among the rubber components (FKM and FFKM) contained in the fluorine-containing elastomer, the more the plasma resistance and heat resistance are improved. However, since FFKM is more expensive than FKM, the cost increases. The proportions of FKM and FFKM in the fluorine-containing crosslinkable rubber may be appropriately set in consideration of the characteristics and cost required for the fluorine-containing elastomer. Although not limited, for example, the proportion of FKM relative to 100 phr of the fluorine-containing crosslinkable rubber may be 0.1 to 99.9. From the perspective of cost rather than the technical perspective, the proportion of FKM relative to 100 phr of the fluorine-containing crosslinkable rubber may be 50.1 to 99.9. Although the description of specific numerical ranges is omitted, any number with one decimal place included in the range of 0.1 to 99.9 may be selected, and the range may be specified as a to b.

[0031] In one embodiment, the fluorine-containing crosslinkable rubber may or may not contain units derived from fluoroolefins having 3 to 8 carbon atoms containing iodine and / or bromine. When the fluorine-containing crosslinkable rubber contains the above units, iodine and / or bromine, more preferably iodine, is preferably contained as a radical attack site during crosslinking (curing). The fluorine-containing crosslinkable rubber curable with a peroxide is described, for example, in JP-A-2006-9010. When the fluorine-containing crosslinkable rubber contains the above units, generally, it contains iodine in an amount of 0.001% by mass to 5% by mass, preferably 0.01% by mass to 2.5% by mass, based on the total polymer mass. The iodine atoms may be present along the chain and / or at the terminal positions of the fluorine-containing crosslinkable rubber.

[0032] <Regarding component (c)> Next, a perfluorinated oligomer of a perfluorinated skeleton as component (c) (hereinafter sometimes referred to as "PFPE") will be described. PFPE has a function of improving the plasma resistance of the fluorine-containing elastomer and also has a function of reducing the hardness. PFPE is an oligomer composed of the elements C, F, and O (in which all hydrogens of hydrocarbons are replaced with fluorine), and examples thereof include fluorine oligomers (c-1) to (c-8) containing the following basic skeletons.

[0033]

Chemical formula

[0034]

Chemical formula

[0035] The PFPEs represented by the above formulas (c-1) to (c-8) have different molecular weights depending on the numbers of n and m, and generally, the higher the molecular weight, the higher the viscosity and boiling point. For the PFPE containing the above basic skeleton, a synthesized one may be used, or a commercially available one as a fluorine-based solvent (oil, grease) may be used. Commercially available PFPEs are known to have various grades with different properties such as viscosity depending on the numbers of n and m. For example, Krytox (registered trademark) series manufactured by DuPont; Fomblin (registered trademark) series, Galden (registered trademark) series of Solvay; Demnum series manufactured by Daikin; and the like. It should be noted that the above products and skeletons are merely examples, and other skeletons and products may be used as long as they do not contain hydrogen. Also, as shown in the above formulas (c-1) to (c-8), PFPE contains an ether bond in the basic skeleton, and PFPEs do not bond (crosslink) with each other during the crosslinking (curing) of the rubber composition. PFPE can be used alone or in combination of two or more of the above-described types.

[0036] In the rubber composition according to the embodiment, non-reactive PFPE is used as the component (c). Alternatively, it may be a reactive compound by bonding a group having reactivity to the perfluoro skeleton.

[0037] The term "reactive" compound means that the reactive compounds can react with each other during the crosslinking (curing) of the rubber composition. By this reaction, the reactive compounds can bond to each other. Also, the reactive compound can react with both the components (a) and (b). By this reaction, the reactive compound can bond to the components (a) and (b). The reactive compound preferably contains an alkenyl group as a group (reactive group) that imparts such reactivity.

[0038] Examples of the alkenyl group include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, and the like. Among these, the vinyl group is preferred as the alkenyl group.

[0039] The reactive compound preferably has two or more alkenyl groups in the molecule. The two or more alkenyl groups may be the same or different.

[0040] In one embodiment, the reactive compound is a compound having a perfluoro skeleton with an alkenyl group. The compound having a perfluoro skeleton with an alkenyl group in the molecule may have, for example, a divalent perfluoropolyether structure or a divalent perfluoroalkylene structure.

[0041] In one embodiment, the reactive compound has a divalent perfluoropolyether structure or a divalent perfluoroalkylene structure and has two or more alkenyl groups at the terminals or side chains. Such reactive compounds can be those similar to, for example, the fluorine-based elastomers described in

[0016] to

[0022] of JP-A-2003-183402, the perfluorocompounds described in JP-A-11-116684 or JP-A-11-116685

[0006] to

[0014] .

[0042] In one embodiment, the reactive compound is represented by the following formula (c-9). CH 2 =CH-(X) p -(R f -Q) a -R f -(X) p -CH=CH 2 (c-9) In formula (c-9), the two Xs are each independently -CH 2 -, -CH 2 O-, CH 2 OCH 2 -, -Y-NR 1 SO 2 - or -Y-NR 1 -CO- (where Y is -CH 2 - or -Si(CH 3 ) 2 -Ph- (Ph: phenylene group)). R 1 is a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group). Rf is a divalent perfluoroalkylene group or a divalent perfluoropolyether group. The two p's are each independently 0 or 1. a is an integer of 0 or more. Also, Q is a divalent group represented by any one of the following formulas (c-10) to (c-12).

[0043]

Chemical formula

[0044] In formulas (c-10) to (c-12), X, p, R 1 are as defined in formula (c-9). R 3 is a substituted or unsubstituted divalent hydrocarbon group. R 4 is a substituted or unsubstituted divalent hydrocarbon group which may have one or more oxygen atoms, nitrogen atoms, silicon atoms and sulfur atoms intervening in the middle of the bond, or a functional group represented by the following formula (c-13) or (c-14).

[0045]

Chemical formula

[0046] In formulas (c-13) and (c-14), R 5 is a substituted or unsubstituted monovalent hydrocarbon group, R 6 is a group containing one or more of carbon atoms, oxygen atoms, nitrogen atoms, silicon atoms and sulfur atoms in the main chain structure.

[0047] In one embodiment, a = 0 in formula (c-9). In this case, formula (c-9) is represented by the following formula (c-15). CH 2 =CH-(X) p -R f -(X) p -CH=CH 2 (c-15) In formula (c-15), X, p, Rf is as defined by formula (c-9).

[0048] R f Specific examples of R include the following groups. -C m F 2n -(m, n: integers of 1 or more) -[CF(CF 3 )OCF 2 p -(CF 2 ) r -[CF 2 OCF(CF 3 )] q - -CF 2 CF 2 -[OCF 2 CF 2 CF 2 w -OCF 2 CF 2 -

[0049] In addition to those exemplified above, the reactive compound may be a compound having a siloxane skeleton with an alkenyl group. Examples of the compound having a siloxane skeleton with an alkenyl group in the molecule include polymers of methylvinylsiloxane, polymers of dimethylsiloxane, copolymers of dimethylsiloxane and methylvinylsiloxane, copolymers of dimethylsiloxane, methylvinylsiloxane and methylphenylsiloxane, and the like. Other examples include organopolysiloxanes containing an alkenyl group in the molecule, which are addition-curable liquid silicone rubbers.

[0050] The reactive compound is also available as a commercial product. Examples thereof include "SIFEL" (registered trademark) manufactured by Shin-Etsu Chemical Co., Ltd.

[0051] ​​As described above, by adding a fluorine oligomer having a perfluoro skeleton and a reactive compound that can be alternatively used (hereinafter, the fluorine oligomer having a perfluoro skeleton and the reactive compound may be collectively referred to as "Compound C"), while the plasma resistance of the fluorine-containing elastomer crosslinked with FKM and FFKM can be significantly improved, when a large amount of Compound C is added, the hardness of the fluorine-containing elastomer becomes low. Further, since Compound C is a liquid lubricating oil having fluidity, it is difficult to knead and mix a large amount of Compound C with FKM and FFKM which are rubber components. Therefore, the lower limit of the Compound C component with respect to 100 phr of the FKM component and the FFKM component which are rubber components is, for example, 0.1 phr or more, 0.2 phr or more, 0.3 phr or more, 0.4 phr or more, 0.5 phr or more, 0.6 phr or more, 0.7 phr or more, 0.8 phr or more, 0.9 phr or more, 1.0 phr or more, 1.1 phr or more, 1.2 phr or more, 1.3 phr or more, 1.4 phr or more, 1.5 phr or more, 1.6 phr or more, 1.7 phr or more, 1.8 phr or more, 1.9 phr or more, 2.0 phr or more. On the other hand, the upper limit of the Compound C component is, for example, 40 phr or less, 39 phr or less, 38 phr or less, 37 phr or less, 36 phr or less, 35 phr or less, 34 phr or less, 33 phr or less, 32 phr or less, 31 phr or less, 30 phr or less, 29 phr or less, 28 phr or less, 27 phr or less, 26 phr or less, 25 phr or less, 24 phr or less, 23 phr or less, 22 phr or less, 21 phr or less, 20 phr or less.

[0052] <Regarding component (d)> Next, the compound represented by the following formula (d-1) which is component (d) will be described. [Chemical formula]

[0053] In formula (d-1), A is a single bond, -O-, -S-, a heteroatom-containing group, a linear or branched alkylene group, a cycloalkylene group, or an arylene group, and in these groups, the hydrogen atoms are not substituted with fluorine atoms, or some or all of the hydrogen atoms are substituted with fluorine atoms. R 1 , R 2 , R 3 and R 4 are each independently a hydrogen atom, a fluorine atom, an alkyl group, a fluorinated alkyl group, or a substituted or unsubstituted aryl group. A plurality of R 1 are the same or different. A plurality of R 2 are the same or different. A plurality of R 3 are the same or different. A plurality of R 4 are the same or different. R 1 , R 2 and R 3 at least one of which is a fluorine atom or a group containing a fluorine atom. m is an integer from 1 to 5. n is an integer from 1 to 5.

[0054] Note that formula (d-1) is the same as formula (b-1) described in the above Patent Document 1 (International Publication No. 2021 / 230231). Therefore, a detailed description of formula (d-1) regarding specific compounds and the like included in formula (d-1) is omitted. The description of formula (d-1) is included in this specification by reference after reading "b" in the description of formula (b-1) described in International Publication No. 2021 / 230231 as "d".

[0055] The compound represented by formula (d-1) functions as a co-crosslinking agent for the rubber components (a) FKM component and (b) FFKM component. Therefore, the (d) component may be added within a range where the rubber components can be suitably crosslinked. Although not limited, the lower limit of the (d) component with respect to 100 phr of the FKM component and FFKM component which are rubber components is, for example, 0.1 phr or more, 0.2 phr or more, 0.3 phr or more, 0.4 phr or more, 0.5 phr or more, 0.6 phr or more, 0.7 phr or more, 0.8 phr or more, 0.9 phr or more, 1.0 phr or more, 1.1 phr or more, 1.2 phr or more, 1.3 phr or more, 1.4 phr or more, 1.5 phr or more, 1.6 phr or more, 1.7 phr or more, 1.8 phr or more, 1.9 phr or more, 2.0 phr or more. On the other hand, the upper limit of the (d) component is, for example, 30 phr or less, 29 phr or less, 28 phr or less, 27 phr or less, 26 phr or less, 25 phr or less, 24 phr or less, 23 phr or less, 22 phr or less, 21 phr or less, 20 phr or less.

[0056] <Regarding the (e) component> Next, the compound represented by the following formula (e-1) which is the (e) component will be described. The rubber composition may optionally contain the (e) component which is a co-crosslinking agent.

Chemical formula

[0057] In formula (e-1), n and m are each 0 or 1. t is an integer of 2 or more. Z is a t-valent linking group.

[0058] Note that formula (e-1) is the same as formula (c-1) described in the above Patent Document 1 (International Publication No. 2021 / 230231). Therefore, a detailed description of formula (e-1) regarding specific compounds and the like included in formula (e-1) will be omitted. The description regarding formula (e-1) is incorporated herein by reference after reading “c” in the description matters regarding formula (c-1) described in International Publication No. 2021 / 230231 as “e”.

[0059] <Regarding component (f)> Next, the organic peroxide which is component (f) will be described. The rubber composition may optionally contain an organic peroxide. When component (f) is included, crosslinking of the rubber composition can proceed suitably. As the organic peroxide, known ones for crosslinking fluorine-based elastomers can be used. Although not limited, for example, dicumyl peroxide, di-t-butylperoxydiisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and the like can be mentioned.

[0060] In addition to the essential components described in (a) to (d) above, and components (e) and (f) which are optional additional components, the rubber composition may contain, for example, a filler, a thickener, a pigment, a coupling agent, an antioxidant, a stabilizer and the like.

[0061] Examples of the filler include fluororesin, carbon black, silica and the like.

[0062] (Embodiment of fluorine-containing elastomer) The fluorine-containing elastomer according to the embodiment can be produced by crosslinking the rubber composition of any embodiment disclosed in the present application. The conditions (crosslinking conditions) during crosslinking of the rubber composition are not particularly limited. For example, the rubber composition may be heated at 100 to 250 ° C for 10 minutes to 5 hours. Usually, as the primary crosslinking, the raw material (rubber composition) is put into a mold and crosslinked while performing press working. The primary crosslinking is, for example, heating at 150 to 200 ° C for 5 to 60 minutes. Then, it is taken out of the mold and subjected to secondary crosslinking in air or an inert gas atmosphere. The secondary crosslinking is, for example, heating at 150 to 300 ° C for 1 to 100 hours. Crosslinking can be carried out using an electric furnace or the like. By giving a heat history in the secondary crosslinking, deformation during use and the like can be prevented. Radiation treatment is not necessarily required during crosslinking, and it is preferable to omit the radiation treatment. The hardness of the fluorine-containing elastomer is not limited, but is, for example, 62 or more or 63 or more. The upper limit of the hardness is also not limited, but for example, 90 or less can be mentioned.

[0063] (Embodiment of sealing material) The sealing material according to the embodiment contains a fluorine-containing elastomer according to any of the embodiments disclosed in the present application. The form of the sealing material is not particularly limited, and examples thereof include molded articles such as gaskets or seal rings. The use of the sealing material is not particularly limited and can be widely applied to various devices. However, since the sealing material disclosed in the present application is excellent in plasma resistance and can have a relatively high hardness, it is suitable as a sealing material for semiconductor manufacturing devices, for example. Examples of semiconductor manufacturing devices include plasma devices, etching devices, plasma CVD devices, and the like.

[0064] Examples are given below to specifically describe the embodiments disclosed in the present application. However, these examples are merely for the purpose of explaining the embodiments and do not represent any limitation or restriction on the scope of the invention disclosed in the present application.

Example

[0065] <Material> The components used in the examples and comparative examples are as follows. Component (a): FKM, Dai-El G912, manufactured by Daikin Industries, Ltd. Component (b): FFKM, AFLAS (registered trademark) FFKM PM3000, manufactured by AGC Inc. Component (c): Compound C (PFPE), Krytox VPF16256, manufactured by DuPont Component (d): Compound represented by the following (d-5)

Chemical formula

Chemical formula

[0066] [Examples 1 to 3, Comparative Examples 1 to 6] The rubber composition having the composition (weight ratio) shown in Table 1 was kneaded on an open roll, then put into a mold and heat-treated in the air at a temperature of 170 °C for 15 minutes, and subjected to primary cross-linking while press-molding. Next, it was taken out of the mold and subjected to secondary cross-linking at 200 °C for 10 hours in the air. In this way, a molded body of the fluorine-containing elastomer was obtained. The shape of the molded body was an O-ring (AS568-214; inner diameter 24.99 mm, thickness 3.53 mm).

[0067] The following evaluations were made on the obtained fluorine-containing elastomer. (1) Hardness The molded body (O-ring) was placed on a BAREISS micro rubber hardness meter (model: HPEII shore AM / M) to measure the hardness.

[0068] (2) Compression set (CS) [%] The molded body (O-ring) was compressed by 25% and treated at 150 °C for 72 hours and 200 °C for 72 hours, then released and left at room temperature for 30 minutes. In accordance with JIS K 6262, the thickness before and after the test was measured, and the compression set was calculated by the following formula. Compression set [%] = 100 × [(thickness before test) - (thickness after test)] / [(thickness before test) - (thickness of spacer)]

[0069] (3) Plasma resistance (3-1) Weight loss rate [%] The molded body (O-ring) was exposed to plasma under the following conditions, and the weight loss rate of the molded body before and after the exposure was calculated. · Equipment: Surface wave plasma etching equipment manufactured by Shinko Seiki Co., Ltd. · Gas: O 2 (2000 sccm) + CF 4 (40 sccm) · Processing pressure: 133 Pa · Output: 3 kW · Exposure time: 2 hours · Weight loss rate [%] = [(weight before plasma exposure) - (weight immediately after plasma exposure)] / (weight before plasma exposure) × 100

[0070] (3-2) Crack-in time An extended molded body (O-ring, elongation rate 15%) was exposed to plasma under the following conditions, and the time until cracks occurred at the extended portion was measured. · Equipment: Surface wave plasma etching equipment manufactured by Shinko Seiki Co., Ltd. · Gas: O 2 (2000 sccm) + CF 4 (40 sccm) · Processing pressure: 133 Pa · Output: 3 kW · Exposure time: Exposed at 10-minute intervals up to 60 minutes, and then at 20-minute intervals.

[0071] (3 - 3) Particles The presence or absence of particle generation associated with the above plasma exposure was visually observed.

[0072] (4) Tensile properties Using a desktop precision universal testing machine (manufactured by Shimadzu Corporation, model: Autograph AGS-500NX), the tensile strength [MPa], elongation at break [%], and M100 [MPa] of the molded body (O-ring) were measured at room temperature of 25 ± 2 °C and a tensile speed of 300 mm / min.

[0073] The above results are shown in Table 1.

Table 1

[0074] As is clear from Table 1, the fluorine-containing elastomer obtained by crosslinking the rubber composition containing each component described in (a) to (d) had a crack-in time of 40 minutes or more. In addition, the fluorine-containing elastomers prepared in Examples 1 to 3 also had an excellent balance of hardness, tensile properties, compression set, and plasma resistance. On the other hand, as shown in Comparative Examples 3 and 4, when only the crack-in time was considered, it was not necessarily necessary to contain each component described in (a) to (d), but it was difficult to uniformly mix FKM and PFPE when kneading the rubber composition.

Industrial Applicability

[0075] By using the rubber composition disclosed in the present application, a fluorine-containing elastomer and a sealing material having good manufacturing processes and balanced properties can be obtained. Therefore, it is useful for the sealing material industry and the semiconductor industry such as plasma processing apparatuses and semiconductor manufacturing apparatuses that use the sealing material.

Claims

1. (a) a crosslinkable fluororubber; (b) a crosslinkable perfluororubber; (c) a fluorooligomer having a perfluoroskeleton; (d) a compound represented by the following formula (d-1); 【Chemical 1】 (In formula (d-1), A is a single bond, -O-, -S-, a heteroatom-containing group, a linear or branched alkylene group, a cycloalkylene group, or an arylene group. In these groups, the hydrogen atoms are not substituted with fluorine atoms, or some or all of the hydrogen atoms are substituted with fluorine atoms. R １ , R ２ , R ３ and R ４ are each independently a hydrogen atom, a fluorine atom, an alkyl group, a fluorinated alkyl group, or a substituted or unsubstituted aryl group. A plurality of R １ are the same or different. A plurality of R ２ are the same or different. A plurality of R ３ are the same or different. A plurality of R ４ are the same or different. R １ , R ２ and R ３ At least one of is a fluorine atom or a group containing a fluorine atom. m is an integer from 1 to 5. n is an integer from 1 to 5.). A rubber composition comprising:

2. (e) a compound represented by the following formula (e-1) (In formula (e-1), n and m are each 0 or 1. t is an integer of 2 or more. Z is a t-valent linking group.) The rubber composition according to claim 1, further comprising:

3. The rubber composition according to claim 1, further comprising: (f) an organic peroxide.

4. The rubber composition according to claim 1, wherein component (c) is contained in an amount of 0.1 phr or more and 40 phr or less per 100 phr of components (a) and (b) which are rubber components.

5. The rubber composition according to claim 1, wherein component (d) is contained in an amount of 0.1 phr or more and 30 phr or less per 100 phr of components (a) and (b) which are rubber components.

6. The rubber composition according to claim 1, wherein the weight ratio of component (b) / component (c) is 0.1 or more and 10 or less.

7. A fluorine-containing elastomer obtained by crosslinking the rubber composition according to any one of claims 1 to 6.

8. A sealing material comprising the fluorine-containing elastomer according to claim 7.

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