Crosslinkable elastomer composition and fluororubber molded article

Abstract

To provide a crosslinkable elastomer composition having a low weight reduction percentage and a small amount of generated particles after plasma irradiation under specific conditions as well as a small compression set at high temperatures.SOLUTION: The invention relates to a crosslinkable elastomer composition including a crosslinkable elastomer and a surface-oxidized non-oxide ceramic filler. Preferably the non-oxide ceramic filler is silicon carbide, and the non-oxide ceramic filler has an average particle size of 0.1 μm or less. Preferably the crosslinkable elastomer is a copolymer of tetrafluoroethylene and perfluoro (alkyl vinyl ether).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a crosslinkable elastomer composition and a fluororubber molded article.

Background Art

[0002] Members used in semiconductor manufacturing apparatuses such as CVD and Ercher need to have resistance to NF3 plasma treatment and O2 treatment to which they are exposed in the manufacturing process. As a composition constituting such a member, Patent Document 1 discloses a composition containing a crosslinkable fluorine-containing elastomer and SiO2. Further, Patent Document 2 discloses a composition containing a crosslinkable fluorine-containing elastomer and silicon carbide particles having a bulk density of 0.15 g / cm 3 The following silicon carbide particles are known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a crosslinkable elastomer composition having a small weight loss rate and particle generation amount after plasma irradiation under specific conditions, and a small compression set at high temperature.

Means for Solving the Problems

[0005] The inventors of the present invention have conducted various studies on the weight loss rate and particle generation amount after plasma irradiation under specific conditions, and the compression set at high temperature, and have found that it can be improved by using a non-oxide ceramic filler whose surface is oxidized, thereby completing the present invention.

[0006] That is, the present invention relates to a crosslinkable elastomer composition containing a crosslinkable elastomer and a non-oxide ceramic filler whose surface is oxidized.

[0007] The non-oxide ceramic filler is preferably silicon carbide.

[0008] The average particle diameter of the non-oxide ceramic filler is preferably 0.1 μm or less.

[0009] The crosslinkable elastomer is preferably a copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether).

[0010] The present invention also relates to a fluororubber molded article having a weight loss rate of 2.5% by mass or less and a particle generation amount of 0.05% by mass or less after O2 plasma irradiation under the following conditions, a weight loss rate of 1.8% by mass or less and a particle generation amount of 0.05% by mass or less after NF3 plasma irradiation, and a compression set of 50% or less at 300 °C for 70 hours. Note Sample: O-ring (AS-568A-214) Measurement method: (1) O2 plasma Plasma irradiation apparatus: ICP high-density plasma apparatus (MODEL RIE-101iPH manufactured by Samco Inc.) Irradiation conditions Gas flow rate: 16 SCCM RF output: 400 Wh Pressure: 2.66 Pa Etching time: 30 minutes Temperature: 100 °C Conditions corresponding to an etching rate of perfluoroelastomer (non-filler) of 12,000 Å / min. (2) NF3 plasma Plasma irradiation apparatus: ICP high-density plasma apparatus (MODEL RIE-101iPH manufactured by Samco Inc.) Irradiation conditions Gas flow rate: 16 SCCM RF output: 400 Wh Pressure: 10 Pa Etching time: 4 hours Temperature: 200 °C Conditions under which the etching rate of the thermal oxide film (SiO2) on the silicon wafer corresponds to 90 Å / min.

Advantages of the Invention

[0011] The crosslinkable elastomer composition of the present invention contains a non-oxide ceramic filler whose surface is oxidized. Therefore, both the weight loss rate after plasma irradiation and the amount of particle generation are small (plasma resistance), and the compression set at high temperature is small (heat resistance).

Embodiments for Carrying Out the Invention

[0012] The crosslinkable elastomer composition of the present invention is characterized by containing a crosslinkable elastomer and a non-oxide ceramic filler whose surface is oxidized. It is not necessary for the entire surface to be oxidized, and a part may be oxidized. The oxidation state of the surface can be confirmed by ESCA (Electron Spectroscopy for Chemical Analysis). In ESCA, elemental analysis of about 3 to 5 nm on the particle surface is possible, so it is possible to confirm whether the surface is oxidized.

[0013] The non-oxide ceramic filler is not particularly limited, and examples thereof include carbides, silicides, sulfides, fluorides, and the like. Examples of the carbide include titanium carbide, boron carbide, zirconium carbide, hafnium carbide, tantalum carbide, tungsten carbide, niobium carbide, silicon carbide, and the like. Examples of the silicide include titanium silicide, molybdenum silicide, zirconium silicide, and the like. Examples of the sulfide include tungsten sulfide, molybdenum disulfide, and the like. Examples of the fluoride include aluminum fluoride, yttrium fluoride, barium fluoride, and the like. Among them, silicon carbide is preferable in that it can achieve both a small weight loss rate and a small amount of particle generation after plasma irradiation (plasma resistance), and a small compression set at high temperature (heat resistance). For example, when using hydrophobic silica, although the compression set can be improved, the weight loss rate with respect to NF3 plasma is large and it does not have sufficient plasma resistance. On the other hand, when using silicon carbide with an unoxidized surface, although the weight loss rate and the amount of particle generation after plasma irradiation can be reduced, the compression set at high temperature is large and the heat resistance is not sufficient.

[0014] For example, in the case of silicon carbide, the surface is oxidized and changed to SiO2. When measured by ESCA, peaks derived from SiO2 and peaks derived from SiC can be observed. The ratio of the peaks derived from SiO2 to the peaks derived from SiC is preferably SiO2:SiC = 1:9 to 9:1, and more preferably 3:7 to 6:4. When the peak ratio is less than 1:9, the surface oxidation is insufficient and a sufficient improvement effect is not exhibited. When it exceeds 9:1, the oxidation is excessive and a sufficient improvement effect also tends not to be exhibited.

[0015] Non-oxide ceramics are preferably made into powder by a pulverization method using a pulverizer such as a jet mill, or a method of forming powder by nucleation and growth from atoms or molecules. In the latter case, it is classified into a gas phase method, a liquid phase method, and a solid phase method depending on the state of the starting material. If the purity of the obtained non-oxide ceramic powder is sufficiently high, the powder production method is not particularly limited. Among non-oxide ceramics, the purity of silicon carbide is preferably 95% or more from the viewpoint of excellent plasma resistance.

[0016] The shape of the non-oxide ceramic filler is not particularly limited, and powder form, particle form, fiber form, whisker form, etc. can be used. From the viewpoint of processability, it is preferably in particle form, and its average particle diameter is preferably 10 μm or less, more preferably 0.1 μm or less. When the average particle diameter exceeds 10 μm, the reinforcing property is poor, it is necessary to increase the compounding amount into the compound, and the performance as a sealing material for the molded body is deteriorated. Furthermore, when used as a sealing material for a semiconductor device, the average particle diameter is preferably 0.1 μm or less, preferably 0.01 to 0.1 μm, because the generation of particles is less. The lower limit of the average particle diameter is not particularly limited.

[0017] Among 100% by mass of the non-oxide ceramic filler, the ratio of the filler whose surface is oxidized by 2 nm or more is not particularly limited, but 10 to 100% by mass is preferable, and 30 to 100% by mass is more preferable.

[0018] The content of the non-oxide ceramic filler is not particularly limited, but it is preferably 1 to 40 parts by mass, more preferably 5 to 25 parts by mass of the non-oxide ceramic filler with respect to 100 parts by mass of the crosslinkable elastomer.

[0019] The preferred content of the non-oxide ceramic filler varies depending on the average particle size of the non-oxide ceramic filler. With respect to 100 parts by mass of the crosslinkable elastomer, when the average particle size is 0.01 to 0.1 μm, it is more preferable to contain 1 to 40 parts by mass of the non-oxide ceramic filler, and even more preferable to contain 5 to 25 parts by mass. When the average particle size is 0.1 to 10 μm, it is more preferable to contain 5 to 50 parts by mass of the non-oxide ceramic filler, and even more preferable to contain 10 to 30 parts by mass.

[0020] The method for oxidizing the surface of the non-oxide ceramic filler is not particularly limited, and examples include heat treatment in air, acid treatment, ozone treatment, oxygen plasma treatment, and the like.

[0021] The heat treatment conditions are not particularly limited, but the heat treatment temperature is preferably 500 to 1000 °C, and more preferably 700 to 900 °C. Below 500 °C, surface oxidation is less likely to occur, and when exceeding 1000 °C, the surface oxidation rate is fast and it is difficult to control the oxide layer thickness, and there is a tendency for oxidation to reach the inside of the particles. The heat treatment time is preferably 0.1 to 24 hours, and more preferably 0.2 to 4 hours.

[0022] The acid used for the acid treatment is not particularly limited, and examples include sulfuric acid aqueous solution, hydrogen peroxide water, nitric acid, and mixed acids thereof. The treatment conditions are not particularly limited, but the treatment temperature is preferably 20 °C to 100 °C, and the treatment time is preferably 0.1 to 24 hours, and more preferably 0.2 to 4 hours.

[0023] The ozone treatment conditions are not particularly limited, but the ozone concentration is preferably 100 to 300 g / N·m 3 , Discharge 40 to 80%, cell pressure 0.1 to 0.3 MPa, O2 flow rate 2 to 5 L / min, N2 flow rate 3 to 10 cc / min, and temperature 100 to 200 °C.

[0024] The oxygen plasma treatment conditions are not particularly limited, but the power is preferably 200 W to 1000 W, the O2 flow rate is preferably 10 to 30 sccm, the pressure is preferably 1 to 5 Pa, the irradiation temperature is 20 to 200 °C, and the irradiation time is 0.1 to 1 hour.

[0025] As the crosslinkable elastomer, fluorine-based elastomers, silicone-based elastomers, etc. can be used, but fluorine-containing elastomers are preferred in terms of heat resistance and resistance to any plasma.

[0026] There is no particular limitation on the fluorine-containing elastomer used in the present invention as long as it has been conventionally used for sealing materials, particularly for sealing materials of semiconductor manufacturing apparatuses.

[0027] Examples of the fluorine-containing elastomer include fluororubber (a), thermoplastic fluororubber (b), and rubber compositions composed of these fluororubbers.

[0028] Examples of the fluororubber (a) include non-perfluorinated fluororubber (a-1) and perfluorinated fluororubber (a-2).

[0029] Examples of the thermoplastic fluororubber (b) include a fluorinated multi-segmented polymer (b-1) composed of an elastomeric fluoropolymer chain segment and a non-elastomeric fluoropolymer chain segment, where 90 mol% or more of the constitutional units of each of the elastomeric fluoropolymer chain segment and the non-elastomeric fluoropolymer chain segment are perhaloolefins; a fluorinated multi-segmented polymer (b-2) composed of an elastomeric fluoropolymer chain segment and a non-elastomeric fluoropolymer chain segment, where 90 mol% or more of the constitutional units of the elastomeric fluoropolymer chain segment are perhaloolefins and the non-elastomeric fluoropolymer chain segment contains less than 90 mol% of perhaloolefins as constitutional units; and a fluorinated multi-segmented polymer (b-3) composed of an elastomeric fluoropolymer chain segment and a non-elastomeric fluoropolymer chain segment, where the elastomeric fluoropolymer chain segment contains less than 90 mol% of perhaloolefins as constitutional units and 90 mol% or more of the constitutional units of the non-elastomeric fluoropolymer chain segment are perhaloolefins or the non-elastomeric fluoropolymer chain segment contains less than 90 mol% of perhaloolefins as constitutional units.

[0030] Examples of the non-perfluorinated fluororubber (a-1) include vinylidene fluoride (VdF)-based fluororubbers, tetrafluoroethylene (TFE) / propylene-based fluororubbers, tetrafluoroethylene (TFE) / propylene / vinylidene fluoride (VdF)-based fluororubbers, ethylene / hexaf luoroethylene (HFP)-based fluororubbers, ethylene / hexaf luoroethylene (HFP) / vinylidene fluoride (VdF)-based fluororubbers, ethylene / hexaf luoropropylene (HFP) / tetrafluoroethylene (TFE)-based fluororubbers, fluorosilicone-based fluororubbers, or fluorophosphazene-based fluororubbers. These can be used alone or in any combination within a range that does not impair the effects of the present invention.

[0031] The vinylidene fluoride-based fluororubber refers to a fluorine-containing elastic copolymer composed of 45 to 85 mol% of vinylidene fluoride and 55 to 15 mol% of at least one other monomer copolymerizable with vinylidene fluoride. Preferably, it refers to a fluorine-containing elastic copolymer composed of 50 to 80 mol% of vinylidene fluoride and 50 to 20 mol% of at least one other monomer copolymerizable with vinylidene fluoride.

[0032] Examples of at least one other monomer copolymerizable with vinylidene fluoride include fluorine-containing monomers such as tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), trifluoroethylene, hexafluoropropylene (HFP), trifluoropropylene, tetrafluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, perfluoro(alkyl vinyl ether) (PAVE), and vinyl fluoride, and non-fluorine monomers such as ethylene, propylene, and alkyl vinyl ether. These can be used alone or in any combination. Among these, it is preferable to use tetrafluoroethylene, hexafluoropropylene, and perfluoro(alkyl vinyl ether).

[0033] Specific rubbers include VdF-HFP-based rubber, VdF-HFP-TFE-based rubber, VdF-CTFE-based rubber, VdF-CTFE-TFE-based rubber, etc.

[0034] The vinylidene fluoride-based fluororubber can be obtained by a conventional method.

[0035] The tetrafluoroethylene / propylene-based fluororubber refers to a fluorine-containing elastic copolymer composed of 45 to 70 mol% of tetrafluoroethylene, 55 to 30 mol% of propylene, and 0 to 5 mol% of a monomer providing a crosslinking site.

[0036] Examples of the monomer that provides the crosslinking site include iodine-containing monomers such as perfluoro(6,6-dihydro-6-iodo-3-oxa-1-hexene) and perfluoro(5-iodo-3-oxa-1-pentene) as described in Japanese Patent Publication No. 5-63482 and Japanese Unexamined Patent Application Publication No. 7-316234, bromine-containing monomers as described in Japanese Unexamined Patent Application Publication No. 4-505341, nitrile group-containing monomers, carboxyl group-containing monomers, and alkoxycarbonyl groups as described in Japanese Unexamined Patent Application Publication No. 4-505345 and Japanese Unexamined Patent Application Publication No. 5-500070.

[0037] Tetrafluoroethylene / propylene-based fluororubbers can also be obtained by a conventional method.

[0038] These non-perfluorinated fluororubbers (a-1) can be produced by a conventional method. Examples of commercially available non-perfluorinated fluororubbers (a-1) include the Dai-El G-800 series and G-900 series manufactured by Daikin Industries, Ltd.

[0039] As the perfluorinated fluororubber (a-2), a copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether) is preferred. For example, a fluorine-containing elastomeric copolymer composed of tetrafluoroethylene / perfluoro(alkyl vinyl ether) / monomer that provides the crosslinking site can be mentioned. The composition is preferably 45-90 / 10-50 / 0-5 (mol%), more preferably 45-80 / 20-50 / 0-5, and even more preferably 53-70 / 30-45 / 0-2. If outside these composition ranges, the properties as a rubber elastomer are lost and tend to become resin-like properties.

[0040] Examples of the perfluoro(alkyl vinyl ether) in this case include perfluoro(methyl vinyl ether) and perfluoro(propyl vinyl ether), and these can be used alone or in any combination within a range that does not impair the effects of the present invention.

[0041] Examples of the monomer that provides the crosslinked portion include, for example, the general formula: CY 1 2=CY 2 R f 2 X 3 (wherein Y 1 and Y 2 are H, F or CH3; R f 2 may have one or more ether-bonding oxygen atoms and may have an aromatic ring, and is a linear or branched fluorine-containing alkylene group in which some or all of the hydrogen atoms are substituted with fluorine atoms; X 3 is an iodine group, a bromine group, a nitrile group, a carboxyl group, an alkoxycarbonyl group, an azide group, an alkyne group). Specific examples include the general formula (1): CX2=CX-RfCHRI (wherein X is H, F or CH3, Rf is a fluoroalkylene group, a perfluoroalkylene group, a fluoropolyoxyalkylene group or a perfluoropolyoxyalkylene group, and R is H or CH3), an iodine-containing monomer represented by the general formula (2): CF2=CF(OCF2CF(CF3)) m -O-(CF2) n -X (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, and X is a nitrile group, a carboxyl group, an alkoxycarbonyl group, a bromine group, an azide group, an alkyne group), and the like. These can be used alone or in any combination within a range that does not impair the effects of the present invention.

[0042] This iodine or nitrile group can function as a crosslinking point.

[0043] The perfluorofluoro rubber (a-2) can be produced by a conventional method.

[0044] Specific examples of such perfluorofluoro rubber (a-2) include fluororubbers described in WO97 / 24381, JP-B-61-57324, JP-B-4-81608, JP-B-5-13961, and the like.

[0045] Next, a fluorine-containing multi-segmented polymer (b-1) which is a thermoplastic fluororubber (b) and is composed of an elastomeric fluoropolymer chain segment and a non-elastomeric fluoropolymer chain segment, and in which 90 mol% or more of each constitutional unit of the elastomeric fluoropolymer chain segment and the non-elastomeric fluoropolymer chain segment is a perhaloolefin, will be described.

[0046] First, the elastomeric fluoropolymer chain segment will be described. The elastomeric fluoropolymer chain segment imparts flexibility to the polymer and has a glass transition temperature of 25°C or lower, preferably 0°C or lower. Examples of the perhaloolefin constituting 90 mol% or more of its constitutional units include tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, and the general formula (3): CF2=CFO(CF2CFYO) p -(CF2CF2CF2O) q -Rf (wherein Y is F or CF3, Rf is a perfluoroalkyl group having 1 to 5 carbon atoms, p is an integer of 0 to 5, and q is an integer of 0 to 5), and fluorovinyl ethers represented thereby, and the like.

[0047] Examples of the constitutional units other than the perhaloolefin constituting the elastomeric fluoropolymer chain segment may include fluorine-containing monomers such as vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, trifluoropropylene, tetrafluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, and vinyl fluoride, and non-fluorine monomers such as ethylene, propylene, and alkyl vinyl ether.

[0048] Preferred examples of the elastomeric fluoropolymer chain segment include an elastomeric polymer chain composed of tetrafluoroethylene / perfluoro(alkyl vinyl ether) / a monomer providing a crosslinking site. The composition is preferably 50 to 85 / 50 to 15 / 0 to 5 (mol%).

[0049] Examples of the monomer providing a crosslinking site include, for example, the general formula: CY 1 2=CY 2 R f 2 X 3 (wherein Y 1 、Y 2 is H, F or CH3; R f 2 may have one or more ether-bonding oxygen atoms and may have an aromatic ring, and is a linear or branched fluorinated alkylene group in which some or all of the hydrogen atoms are substituted with fluorine atoms; X 3 is an iodine group, a bromine group, a nitrile group, a carboxyl group, an alkoxycarbonyl group, an azide group, an alkyne group). Specifically, the general formula (4): CX2=CX-RfCHRX 1 (wherein X is H, F or CH3, Rf is a fluoroalkylene group, a perfluoroalkylene group, a fluoropolyoxyalkylene group or a perfluoropolyoxyalkylene group, R is H or CH3, X 1 is iodine or bromine), an iodine-containing monomer represented by the general formula (5): CF2=CF(OCF2CF(CF3)) m -O-(CF2) n -X (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, and X is a nitrile group, a carboxyl group, an alkoxycarbonyl group, a bromine group, an azide group, an alkyne group), and the like.

[0050] This iodine, bromine, and nitrile group, carboxyl group, alkoxycarbonyl group can function as crosslinking points.

[0051] Next, the non-elastomeric fluorine-containing polymer chain segment will be described. Examples of perhaloolefins that constitute 90 mol% or more of the structural units of the non-elastomeric fluorine-containing polymer chain segment include tetrafluoroethylene, chlorotrifluoroethylene, perfluoro(alkyl vinyl ether), hexafluoropropylene, general formula (6): CF2=CF(CF2) p X (wherein p is an integer of 1 to 10, and X is F or Cl), and perhaloolefins such as perfluoro-2-butene.

[0052] Examples of the structural units other than perhaloolefins that constitute the non-elastomeric fluorine-containing polymer chain segment may be, for example, fluorine-containing monomers such as vinylidene fluoride, trifluoroethylene, tetrafluoroethylene, trifluoropropylene, tetrafluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, vinyl fluoride, and non-fluorine monomers such as ethylene, propylene, and alkyl vinyl ether.

[0053] Preferred examples of the non-elastomeric fluorine-containing polymer chain segment include an inelastic polymer chain composed of 85 to 100 mol% of tetrafluoroethylene and 0 to 15 mol% represented by general formula (7): CF2=CF-Rf (wherein Rf is Rf 1 or -ORf 1 and Rf 1 is a perfluoroalkyl group having 1 to 5 carbon atoms).

[0054] Further, from the viewpoint of the heat resistance of the resulting thermoplastic fluororubber (fluorine-containing multi-segmented polymer), the crystal melting point of the non-elastomeric fluorine-containing polymer chain segment is preferably 150°C or higher, more preferably 200 to 360°C.

[0055] That is, it is important that the fluorine-containing multi-segmented polymer (b-1) is a fluorine-containing multi-segmented polymer in which an elastomeric fluorine-containing polymer chain segment and a non-elastomeric fluorine-containing polymer chain segment are bonded in the form of blocks or grafts in one molecule.

[0056] Therefore, as a method for producing the fluorine-containing multi-segmented polymer (b-1), various known methods can be adopted to connect an elastomeric segment and a non-elastomeric segment in the form of blocks or grafts to form a fluorine-containing multi-segmented polymer. Among them, the production method of the block-type fluorine-containing multi-segmented polymer shown in Japanese Patent Publication No. 58-4728 and the production method of the graft-type fluorine-containing multi-segmented polymer shown in Japanese Patent Application Laid-Open No. 62-34324 can be preferably adopted.

[0057] In particular, since the segmentalization rate (blocking rate) is high and a homogeneous and regular segmented polymer can be obtained, the block-type fluorine-containing multi-segmented polymer synthesized by the so-called iodine transfer polymerization method described in Japanese Patent Publication No. 58-4728 and Polymer Journal (Vol. 49, No. 10, 1992) is preferable.

[0058] On the other hand, when a simple mixture of an elastomeric fluorine-containing polymer and a non-elastomeric fluorine-containing polymer is used, it varies depending on the types, miscibility, and compatibility of the respective polymers to be mixed. Generally, the mechanical properties (especially at high temperatures) become insufficient, the wear resistance decreases, the flexibility decreases, and the durability decreases.

[0059] In contrast, by bonding an elastomeric segment and a non-elastomeric segment with blocks or grafts to form a multi-segmented polymer, the heat resistance, mechanical properties (especially at high temperatures), etc. are improved compared to simply mixing the above-mentioned elastomeric fluorine-containing polymer and non-elastomeric fluorine-containing polymer.

[0060] The elastomeric segment can be produced by the iodine transfer polymerization method known as a method for producing fluororubber (Japanese Patent Publication No. 58-4728, Japanese Unexamined Patent Publication No. 62-12734). For example, in a substantially oxygen-free state, in an aqueous medium, in the presence of an iodine compound, preferably a diiodine compound, the perhaloolefin and, if necessary, a monomer that provides a curing site are emulsified and polymerized under pressure while stirring in the presence of a radical initiator. A method can be given. Representative examples of the diiodine compound to be used include, for example, 1,3-diiodoperfluoropropane, 1,4-diiodoperfluorobutane, 1,3-diiodo-2-chloroperfluoropropane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, and 1,16-diiodoperfluorohexadecane, diiodomethane, and 1,2-diiodoethane. These compounds may be used alone or in combination with each other. Among them, 1,4-diiodoperfluorobutane is preferred. The amount of the diiodine compound is 0.01 to 1% by mass based on the total mass of the elastomeric segment.

[0061] The terminal portion of the elastomeric segment thus obtained is of a perhalo type and has an iodine atom that serves as a starting point for the block copolymerization of the non-elastomeric segment.

[0062] The radical polymerization initiator used in the production of the elastomeric segment in the present invention may be the same as those conventionally used in the polymerization of fluorine-based elastomers. These initiators include organic and inorganic peroxides and azo compounds. Typical initiators include persulfates, peroxycarbonates, peroxy esters, etc., and ammonium persulfate (APS) can be mentioned as a preferred initiator. APS may be used alone or in combination with a reducing agent such as sulfites and sulfites.

[0063] The elastomeric segment thus obtained, having a number average molecular weight of 5,000 to 750,000, particularly 20,000 to 400,000, is preferable from the viewpoints of imparting flexibility, elasticity, and mechanical properties to the entire fluorine-containing multi-segmented polymer obtained.

[0064] Subsequently, the block copolymerization of the non-elastomeric segment can be carried out by changing the monomer for the non-elastomeric segment following the emulsion polymerization of the elastomeric segment.

[0065] The number average molecular weight of the non-elastomeric segment can be adjusted within a wide range of 1,000 to 1,200,000, preferably 3,000 to 600,000.

[0066] The fluorine-containing multi-segmented polymer (b-1) thus obtained mainly consists of polymer molecules having non-elastomeric segments bonded to both sides of the elastomeric segment and polymer molecules having non-elastomeric segments bonded to one side of the elastomeric segment. The polymer molecules consisting only of the elastomeric segment without the bonded non-elastomeric segment are 20% by mass or less, preferably 10% by mass or less, based on the total amount of the segments and polymer molecules in the fluorine-containing multi-segmented polymer.

[0067] Next, a fluorine-containing multi-segmented polymer (b-2) composed of an elastomeric fluorine-containing polymer chain segment and a non-elastomeric fluorine-containing polymer chain segment, wherein 90 mol% or more of the constitutional units of the elastomeric fluorine-containing polymer chain segment are perhaloolefins, and the non-elastomeric fluorine-containing polymer chain segment contains less than 90 mol% of perhaloolefins as constitutional units, will be described.

[0068] The elastomeric fluorine-containing polymer chain segment in this case may be the same as that described for the fluorine-containing multi-segmented polymer (b-1).

[0069] The non-elastomeric fluorine-containing polymer chain segment is a polymer chain having a crystal melting point of 150 °C or higher, preferably 200 to 360 °C.

[0070] Examples of the structural unit of the non-elastomeric fluorine-containing polymer chain segment include vinylidene fluoride, vinyl fluoride, trifluoroethylene, and the general formula (8): CH2=CX-(CF2) q -X (wherein X is H or F, and q is an integer of 1 to 10), and partially fluorinated olefins such as CH2=C(CF3)2.

[0071] In addition, monomers such as ethylene, propylene, vinyl chloride, vinyl ether, vinyl carboxylate, and acrylic acid that are copolymerizable with these monomers can also be used as copolymer components.

[0072] Also, the fluorine-containing multi-segment polymer (b-2) can be produced in the same manner as the fluorine-containing multi-segment polymer (b-1).

[0073] Next, a fluorine-containing multi-segment polymer (b-3) composed of an elastomeric fluorine-containing polymer chain segment and a non-elastomeric fluorine-containing polymer chain segment, wherein the elastomeric fluorine-containing polymer chain segment contains less than 90 mol% of perhaloolefin as a structural unit, and 90 mol% or more of the structural units of the non-elastomeric fluorine-containing polymer chain segment are perhaloolefins or contain less than 90 mol% of perhaloolefin as a structural unit will be described.

[0074] The elastomeric fluorine-containing polymer chain segment in the fluorine-containing multi-segment polymer (b-3) is a polymer chain having a glass transition point of 25 °C or lower, preferably 0 °C or lower.

[0075] Further, the elastomeric fluoropolymer chain segment contains less than 90 mol% of perhaloolefin as a constitutional unit. As the constitutional units other than the perhaloolefin in this case, those described for the vinylidene fluoride-based fluororubber of the non-perfluorinated fluororubber (a-1) may be the same.

[0076] The non-elastomeric fluoropolymer chain segment in the fluorinated multi-segmented polymer (b-3) may be the same as the non-elastomeric fluoropolymer chain segment in the fluorinated multi-segmented polymers (b-1) or (b-2) described above. In particular, it may be the same as the non-elastomeric fluoropolymer chain segment in (b-2).

[0077] Further, the fluorinated multi-segmented polymer (b-3) consists of 40 to 95% by mass of an elastomeric fluoropolymer chain segment and 5 to 60% by mass of a non-elastomeric fluoropolymer chain segment.

[0078] Such a fluorinated multi-segmented polymer (b-3) can be produced in the same manner as the fluorinated multi-segmented polymers (b-1) and (b-2).

[0079] Specific examples of the fluorinated multi-segmented polymer (b-3) include, for example, Dai-El Thermo T-530, T-550, T-630 manufactured by Daikin Industries, Ltd., and Cephal Soft manufactured by Central Glass Co., Ltd.

[0080] In the present invention, a composition comprising the above-described fluororubber (a) and thermoplastic fluororubber (b) can also be used.

[0081] As the first fluororubber composition comprising a non-perfluorinated fluororubber (a-1) and a fluorine-containing multi-segmented polymer (b-1), the non-perfluorinated fluororubber (a-1) and the fluorine-containing multi-segmented polymer (b-1) obtained as described above can be mixed at an arbitrary ratio by mixing in a dispersion state or dry blending by an open roll or the like.

[0082] Further, for the purpose of improving the mold release property during molding and the like, additives such as internal mold release agents can be appropriately blended within a range not impairing the effects of the present invention.

[0083] The second fluororubber composition comprising a non-perfluorinated fluororubber (a-1) and a fluorine-containing multi-segmented polymer (b-2) is obtained in the same manner as the first fluororubber composition.

[0084] In this case, the above-described additives can be appropriately blended within a range not impairing the effects of the present invention, and a crosslinking agent can also be blended according to the type of crosslinking method described later.

[0085] The third fluororubber composition comprising a perfluorinated fluororubber (a-2) and a fluorine-containing multi-segmented polymer (b-3) is obtained in the same manner as the first fluororubber composition.

[0086] Further, the above-described additives can be appropriately blended within a range not impairing the effects of the present invention, and a crosslinking agent can also be blended according to the type of crosslinking method described later.

[0087] The fourth fluororubber composition comprising a perfluorinated fluororubber (a-2) and a fluorine-containing multi-segmented polymer (b-1) is obtained in the same manner as the first fluororubber composition.

[0088] Both the perfluorofluoro rubber (a-2) and the fluorine-containing multi-segmented polymer (b-1) are inferior in the efficiency of radiation crosslinking and cannot be substantially radiation crosslinked. Therefore, when crosslinking, a crosslinking site such as peroxide crosslinking must be introduced into at least one of the rubbers for crosslinking.

[0089] As the fluorine rubber into which a crosslinking site is introduced, a fluorine rubber in which iodine or bromine is introduced at the end of the polymer is preferable. When this fluorine rubber is produced by polymerization, a compound represented by the general formula (9): RI x Br y (In the formula, R is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, x and y are each an integer of 0 to 2, and 1 ≤ x + y ≤ 2) is obtained by the presence of a compound represented by. The iodine or bromine thus introduced functions as a crosslinking point.

[0090] General formula (9): RI x Br y (In the formula, R is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, x and y are each an integer of 0 to 2, and 1 ≦ x + y ≦ 2). Examples of the compound represented thereby include 1,3-diiodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, CF2Br2, BrCF2CF2Br, CF3CFBrCF2Br, CFClBr2, BrCF2CFClBr, CFBrClCFClBr, BrCF2CF2CF2Br, BrCF2CFBrOCF3, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo substitution products of benzene, diiodomonobromo substitution products, and (2-iodoethyl) and (2-bromoethyl) substitution products, etc.

[0091] Among these, from the viewpoints of polymerization reactivity, crosslinking reactivity, availability, etc., it is preferable to use 1,4-diiodoperfluorobutane, diiodomethane, etc.

[0092] General formula (9): RI x Br y (In the formula, R is a saturated or unsaturated fluorohydrocarbon group or chlorofluorohydrocarbon group having 1 to 16 carbon atoms, or a hydrocarbon group having 1 to 3 carbon atoms, x and y are each an integer of 0 to 2, and 1 ≦ x + y ≦ 2). The addition amount of the compound represented thereby may be 0.0001 to 5% by mass of the total mass of the resulting fluororubber, and more preferably 0.01 to 1% by mass.

[0093] As another method for introducing the crosslinked portion, there is a method of copolymerizing a small amount of a monomer that provides the crosslinked portion.

[0094] Examples of such monomers include iodine-containing monomers such as perfluoro(6,6-dihydro-6-iodo-3-oxa-1-hexene) and perfluoro(5-iodo-3-oxa-1-pentene) as described in Japanese Patent Publication No. 5-63482 and Japanese Unexamined Patent Application Publication No. 7-316234, bromine-containing monomers as described in Japanese Unexamined Patent Application Publication No. 4-505341, nitrile group-containing monomers as described in Japanese Unexamined Patent Application Publication No. 4-505345 and Japanese Unexamined Patent Application Publication No. 5-500070, carboxyl groups, alkoxycarbonyl groups, etc., which are suitable.

[0095] The fifth fluororubber composition comprising the perfluorofluororubber (a-2) and the fluorine-containing multi-segmented polymer (b-2) is obtained in the same manner as the first fluororubber composition.

[0096] In this case, the above-described additives can be appropriately blended within a range that does not impair the effects of the present invention, and a crosslinking agent can also be blended according to the type of crosslinking method described later.

[0097] The monomer mixed gas used in the present invention has explosiveness as described by Kalb, G.H. et al., Advances in Chemistry Series. 129, 13 (1973), so it is necessary to devise the polymerization apparatus so that no sparks or the like that serve as ignition sources are generated. Also, in that sense, it is preferable to keep the polymerization pressure as low as possible.

[0098] The polymerization pressure can be varied within a wide range. Generally, it is in the range of 0.5 to 5 MPa. Since the polymerization rate increases as the polymerization pressure increases, from the viewpoint of improving productivity, it is preferably 0.8 MPa or more.

[0099] Some of the polymerization products thus obtained may not contain free carboxyl groups depending on the polymerization conditions, but they can also be converted into free carboxyl groups by subjecting them to the following acid treatment.

[0100] In addition, examples of the silicone-based elastomer used in the present invention include silicone rubber and fluorosilicone rubber.

[0101] Among the crosslinkable elastomers thus obtained, the fluorine-containing elastomer used in the present invention is preferably a copolymer composed of tetrafluoroethylene / perfluoro(alkyl vinyl ether) / a monomer having a crosslinkable reactive group from the viewpoints of heat resistance and chemical resistance.

[0102] Examples of the perfluoro(alkyl vinyl ether) include perfluoro(methyl vinyl ether) (PMVE), perfluoro(ethyl vinyl ether) (PEVE), perfluoro(propyl vinyl ether) (PPVE), etc., and PMVE is preferred from the viewpoint of excellent cold resistance.

[0103] In addition, the monomer for introducing the crosslinking point is preferably an iodine-containing monomer, a nitrile group-containing monomer, a carboxyl group-containing monomer, or an alkoxycarbonyl group-containing monomer in terms of copolymerization reactivity. Further, a nitrile group-containing monomer is more preferred in terms of crosslinking reactivity and the heat resistance of the crosslinked structure formed by the crosslinking reaction.

[0104] Examples of the method for introducing a carboxyl group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or a sulfonic acid group into the polymer terminal group of the crosslinkable elastomer include the acid treatment method described later.

[0105] The crosslinkable elastomer can be produced by a polymerization method such as an emulsion polymerization method, a suspension polymerization method, or a solution polymerization method.

[0106] As the emulsifier used in emulsion polymerization, a wide range of emulsifiers can be used. However, from the viewpoint of suppressing the chain transfer reaction to the emulsifier molecules during polymerization, salts of carboxylic acids having a fluorocarbon chain or a fluoropolyether chain are desirable. The amount of the emulsifier used is preferably about 0.05 to 2% by mass, more preferably 0.2 to 1.5% by mass, based on the added water.

[0107] As the polymerization initiator used for the polymerization of the crosslinkable elastomer, those that can preferably have a carboxyl group or a group capable of generating a carboxyl group (for example, acid fluoride, acid chloride, CF2OH. All of these generate a carboxyl group in the presence of water) at the elastomer terminal are used. Specific examples include ammonium persulfate (APS), potassium persulfate (KPS), and the like.

[0108] Also, a chain transfer agent usually used for adjusting the molecular weight may be used. However, since the ratio of the group capable of generating a carboxyl group or an alkoxycarbonyl group introduced at the terminal decreases, it is better not to use it as much as possible. However, this is not the case if the chain transfer agent can cause the above group to be present at the elastomer terminal. When the chain transfer agent is not used, the molecular weight can be adjusted by carrying out the polymerization at a low pressure, for example, less than 2 MPa·G, preferably 1 MPa·G or less. Other polymerization conditions are not particularly limited. However, in order to obtain a polymerization product having a carboxyl group at the terminal and / or in the branched chain without undergoing the acid treatment described later, it is preferable to make the pH of the polymerization system strongly acidic at 3 or less.

[0109] The crosslinkable elastomer used in the present invention preferably converts groups such as metal salts and ammonium salts of carboxylic acids present in the polymerization product into carboxyl groups by subjecting the polymerization product to an acid treatment. As the acid treatment method, for example, washing with hydrochloric acid, sulfuric acid, nitric acid, etc., or a method of adjusting the pH of the mixture system after the polymerization reaction to 3 or less with these acids is appropriate.

[0110] This acid treatment is preferably applied as a coagulation means for isolating the polymerization product from the polymerization reaction mixture by coagulation in terms of process simplification. Alternatively, the polymerization mixture may be acid-treated, and then the polymerization product may be isolated by means such as freeze-drying. Furthermore, methods such as coagulation by ultrasonic waves or coagulation by mechanical force can also be employed.

[0111] Also, a crosslinkable elastomer containing iodine or bromine can be oxidized with fuming nitric acid to introduce a carboxyl group.

[0112] The curing agent used in the present invention can be carried out with curing agents such as peroxide crosslinking systems, polyol crosslinking systems, polyamine crosslinking systems, triazine crosslinking systems, oxazole crosslinking systems, imidazole crosslinking systems, thiazole crosslinking systems, radiation crosslinking systems, and the like.

[0113] The curing agent used in peroxide crosslinking may be any organic peroxide that can easily generate peroxy radicals in the presence of heat or a redox system. Specifically, for example, 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroperoxide, di-t-butyl peroxide (Perbutyl D), t-butyl cumyl peroxide (Perbutyl C), dicumyl peroxide (Perkyl D, Perkyl D-40, Perkyl D-40MB(T)), α,α-bis(t-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (Perhexa 25B, Perhexa 25B-40), 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3 (Perhexyne 25B, Perhexyne 25B-40), benzoyl peroxide, t-butyl peroxybenzene, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane (Perhexa 25Z), t-butyl peroxymaleic acid (t-butyl MA), t-butyl peroxyisopropyl carbonate (Perbutyl I-75), methyl ethyl ketone peroxide (Permek D (DR), Permek H (HR, HY), Permek N (NR, NY), Permek S (SR), Permek F (FR), Permek G (GR, GY)), cyclohexanone peroxide (Perhexa H), acetylacetone peroxide (Perkure AH, AL), 1,1-di(t-hexylperoxy)-3,3,5-trimethylcyclohexane (Perhexa TMH), 1,1-di(t-hexylperoxy)cyclohexane (Perhexa HC), 1,1-di(t-butylperoxy)-2-methylcyclohexane (Perhexa MC), 1,1-di(t-butylperoxy)cyclohexane (Perhexa C-80(S), Perhexa C-75(EB), Perhexa C(C), Perhexa C-40, Perhexa C-40MB(S)), 2,2-di(t-butylperoxy)butane (Perhexa 22), butyl 4,4-di-(t-butylperoxy)pentanoate (Perhexa V, Perhexa V-40(F)), 2,2-di(4,4-Di-(t-butylperoxy)cyclohexyl)propane (Per-Tetra A), p-menthane hydroperoxide (Per-Menth H), diisopropylbenzene hydroperoxide (Per-Cumyl P), 1,1,3,3-tetramethylbutyl hydroperoxide (Per-Octa H), cumene hydroperoxide (Per-Cumyl H-80), t-butyl hydroperoxide (Per-Butyl H-69), di(2-t-butylperoxyisopropyl)benzene (Per-Butyl P, Per-Butyl P-40, Peroximon F-40, Per-Butyl P-40MB(K)), di-t-hexyl peroxide (Per-Hexyl D), diisobutyryl peroxide (Per-Loyl IB), di(3,5,5-trimethylhexanoyl) peroxide (Per-Loyl 355(S)), dilauroyl peroxide (Per-Loyl L), disuccinic peroxide (Per-Loyl SA), di-(3-methylbenzoyl) peroxide, benzoyl(3-methylbenzoyl) peroxide, and a mixture of dibenzoyl peroxide (Naiper BMT-K40, Naiper BMT-M), dibenzoyl peroxide (Naiper BW, Naiper BO, Naiper FF, Naiper BS, Naiper E, Naiper NS), di(4-methylbenzoyl) peroxide (Naiper PMB), di-n-propyl peroxydicarbonate (Per-Loyl NPP-50M), diisopropyl peroxydicarbonate (Per-Loyl IPP-50, Per-Loyl IPP-27), di(4-t-butylcyclohexyl) peroxydicarbonate (Per-Loyl TCP), di(2-ethylhexyl) peroxydicarbonate (Per-Loyl OPP), di-sec-butyl peroxydicarbonate (Per-Loyl SBP), cumyl peroxypivalate (Per-Cumyl ND, Per-Cumyl ND-50E), 1,1,3,3-Tetramethylbutyl peroxyneodecanoate (Perocta ND, Perocta ND-50E), t-hexyl peroxyneodecanoate (Perhexyl ND, Perhexyl ND-50E), t-butyl peroxyneodecanoate (Perbutyl ND, Perbutyl ND-50E), t-butyl peroxyneoheptanoate (Perbutyl NHP), t-hexyl peroxypivalate (Perhexyl PV, Perhexyl PV-50E), t-butyl peroxypivalate (Perbutyl PV, Perbutyl PV-40E), 1,1,3,3-Tetramethylbutyl peroxy-2-ethylhexanoate (Perocta O), 2,5-Dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane (Perhex25O), t-hexyl peroxy-2-ethylhexanoate (Perhexyl O, Perkure HO(N)), t-butyl peroxy-2-ethylhexanoate (Perbutyl O, Perkure O), t-hexyl peroxyisopropyl monocarbonate (Perhexyl I), t-butyl peroxy-3,5,5-trimethylhexanoate (Perbutyl 355), t-butyl peroxylaurate (Perbutyl L), t-butyl peroxy-2-ethylhexyl monocarbonate (Perbutyl E), t-hexyl peroxybenzoate (Perhexyl Z), t-butyl peroxyacetate (Perbutyl A), A mixture of t-butyl peroxy-3-methylbenzoate and t-butyl peroxybenzoate (Perbutyl ZT), t-butyl peroxybenzoate (Perbutyl Z), t-butyl peroxyallyl monocarbonate (Peromer AC), 3,3’,4,4’-Tetra(t-butylperoxycarbonyl)benzophenone (BTTB-25), 2,3-Dimethyl-2,3-diphenylbutane (Nofmer BC-90), etc. can be mentioned. Among them, the preferred ones are those of the dialkyl type. Further, 2,5-Dimethyl-2,5-di(t-butylperoxy)hexane is particularly preferred. Generally, the type and amount of the organic peroxide are selected in consideration of the amount of active -O-O-, decomposition temperature, etc.,

[0114] In addition, as the curing aid that can be used in this case, any compound having reactivity with peroxy radicals and polymer radicals may be used. For example, polyfunctional compounds having functional groups such as CH2=CH-, CH2=CHCH2-, CF2=CF-, CF2=C(CF3)-, CF2=C(CH3)-, CF(CF3)=CF-, CF(CH3)=CF-, CF2=C(C6H5)-, CF(C6H5)=CF-, CF2=CH-, CHF=CF-, CHF=C(CF3)-, CH(CF3)=CF-, CF(CF3)=CH- etc. can be mentioned (in each formula, "C6H5" represents a phenyl group). Specifically, for example, triallyl cyanurate, triallyl isocyanurate (TAIC), triacryl formal, triallyl trimellitate, N,N'-n-phenylene bismaleimide, dipropynyl terephthalate, diallyl phthalate, tetraallyl terephthalamide, triallyl phosphate, bismaleimide, fluorinated triallyl isocyanurate (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-diallyl acrylamide, 1,6-divinyldodecafluorhexane, general formula (I): [Chemical formula] (wherein R1, R2, R3, R4, R5 and R6, which may be the same as or different from each other, are H, halogen, or an optionally halogenated group optionally containing one or more oxygen groups; Z is a linear or branched optionally halogenated alkylene group or cycloalkylene group, arylene group, or (per)fluoropolyoxyalkylene group optionally containing a hetero atom) and the like can be mentioned. As the compound represented by general formula (I), formula (II): [Chemical formula] (wherein A IIis a single bond, a heteroatom-containing group, a linear or branched alkylene group, a cycloalkylene group, or an arylene group, and these groups may be partially or completely fluorinated. R II1 is an alkyl group. R II2 , R II3 are each independently a hydrogen atom, a fluorine atom, an alkyl group, a fluoroalkyl group, or a substituted or unsubstituted aryl group. A plurality of R II1 may be the same or different. A plurality of R II2 may be the same or different. A plurality of R II3 may be the same or different. Provided that R II2 , R II3 at least one of is a fluorine atom or a group containing a fluorine atom. n is an integer from 1 to 5, respectively. The hydrogen of the benzene ring may be substituted. A compound represented by the formula (III):

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0115] (wherein R VI1 to R VI3 are independently a hydrogen atom, a fluorine atom, an alkyl group, a fluorinated alkyl group, or a substituted or unsubstituted aryl group, and at least one of R VI1 to R VI3 is a fluorine atom or a group containing a fluorine atom. m is an integer from 1 to 5. When m is 2 or more, the m R VI1 to R VI3 may be the same or different from each other. The hydrogen atoms of the benzene ring may be substituted. Compounds having at least one structure represented by formula (VI) etc. are exemplified. When m is 1, it is preferable to have two or more of the structures. The heteroatom-containing group is a group containing a heteroatom other than a carbon atom. Examples of the heteroatom include an oxygen atom, a nitrogen atom, a sulfur atom, etc. Examples of the heteroatom-containing group include, for example, -O-, -S-, -SO2-, -CO-, etc.

[0116] Examples of the compound having the structure represented by the general formula (VI) include the general formula: [Chemical formula]

[0117] (wherein, R VI1 ~R VI3 are as described above. p is an integer from 0 to 2, and n is an integer from 2 to 6.) Examples thereof include compounds represented by the formula.

[0118] Examples of the curing agent used for polyol crosslinking include polyhydric alcohol compounds such as bisphenol A and bisphenol AF.

[0119] Examples of the curing agent used for polyamine crosslinking include polyvalent amine compounds such as hexamethylene diamine carbamate, N,N'-dicyclohexylidene-1,6-hexanediamine, and 4,4'-bis(aminocyclohexyl)methane carbamate.

[0120] Examples of the curing agent used for triazine crosslinking include organotin compounds such as tetraphenyltin and triphenyltin. Further, in order to cause a cyanide group in a fluorine-containing elastomer to undergo a cyclotrimerization reaction to advance a triazine crosslinking reaction, a non-oxide filler such as silicon nitride can also be blended.

[0121] Examples of the curing agent used for oxazole crosslinking system, imidazole crosslinking system, and thiazole crosslinking system include, for example, general formula (10): [Chemical formula] (wherein, R 1 is -SO2-, -O-, -CO-, an alkylene group having 1 to 6 carbon atoms, a perfluoroalkylene group having 1 to 10 carbon atoms, or a single bond, and R 2 and R 3 are such that one is -NH2 and the other is -NH2, -OH, or -SH, preferably R 2 and R 3A bis-diaminophenyl curing agent, bis-aminophenol curing agent, bis-aminothiophenol curing agent, all represented by -NH2), general formula (11): [Chemical formula] A bis-amidrazone curing agent represented by general formula (12) or general formula (13): [Chemical formula] (wherein, R f is a perfluoroalkylene group having 1 to 10 carbon atoms), [Chemical formula] A bis-amidoxime curing agent represented by (wherein, n is an integer from 1 to 10), formula (VI): R VI1 N=CR VI2 R VI3 (VI) (wherein, R VI1 is H, R VI2 is selected from the group consisting of H, NH2, and NR VI4 R VI5 , R VI3 is selected from the group consisting of Ph, SO2H, NR VI6 R VI7 , 2-pyridine, and CH2CONH2, R VI4 is H, R VI5 is selected from the group consisting of Ph, NH2, and CN, R VI6 is selected from the group consisting of H, NHPh, CCONH2, C 1 ~C 8 linear alkyl groups, and C 1 ~C 8 branched alkyl groups, and R VI7 is selected from the group consisting of Ph, COOC(CH3)3, NH2, CH2COOH, CSNH2, CNHNH3 + Cl-, p-phenyl CN, COPh, [Chemical formula] Compounds represented by (selected from the group consisting of) etc. can be mentioned. These bisaminophenol-based curing agents, bisaminothiophenol-based curing agents, bisdiaminophenyl-based curing agents, etc. were conventionally used in crosslinking systems having nitrile groups as crosslinking points, but they also react with carboxyl groups and alkoxycarbonyl groups to form oxazole rings, thiazole rings, and imidazole rings, giving crosslinked products.

[0122] Among these curing agents, those having particularly excellent heat resistance, good crosslinking reactivity, and relatively easy synthesis are more preferable as curing agents. The general formula (14):

Chemical formula

[0123] Furthermore, more preferable curing agents include those represented by the general formula (15):

Chemical formula

[0124] The substituent R in the crosslinkable reaction group 6 is a monovalent organic group other than hydrogen or a fluorine atom, and particularly a substituent that forms an N-R 6 bond having higher oxidation resistance than the N-H bond is preferable. Here, the "substituent that forms an N-R 6 bond having higher oxidation resistance than the N-H bond" refers to a substituent that forms an N-R 6 bond present in a compound that is more difficult to oxidize than a compound having an N-H bond when an imidazole ring is formed.

[0125] Such R 6Examples include, but are not limited to, an optionally substituted aliphatic hydrocarbon group, an optionally substituted phenyl group or benzyl group.

[0126] Specific examples include, for example, when at least one of R 6 is a lower alkyl group having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms such as -CH3, -C2H5, -C3H7; a fluorine atom-containing lower alkyl group having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms such as -CF3, -C2F5, -CH2F, -CH2CF3, -CH2C2F5; a phenyl group; a benzyl group; a phenyl group or benzyl group in which 1 to 5 hydrogen atoms are substituted with fluorine atoms such as -C6F5, -CH2C6F5; -C6H5-n(CF3) n , -CH2C6H5-n(CF3) n (n is an integer from 1 to 5), and a phenyl group or benzyl group in which 1 to 5 hydrogen atoms are substituted with -CF3 such as etc.

[0127] Among these, a phenyl group and -CH3 are preferred because of their particularly excellent heat resistance, good crosslinking reactivity, and relatively easy synthesis.

[0128] In the compound of general formula (15), R 7 is -SO2-, -O-, -CO-, an optionally substituted alkylene group,

Chemical formula

[0129] R 7 Preferred specific examples of the optionally substituted alkylene group of include, but are not limited to, for example, an unsubstituted alkylene group having 1 to 6 carbon atoms or a perfluoroalkylene group having 1 to 10 carbon atoms. Examples of the perfluoroalkylene group include

Chemical formula

[0130] R 7 In either of the left and right benzene rings, it may be bonded at any position. However, since synthesis is easy and the crosslinking reaction proceeds easily, it is preferably bonded so that either the NH2 group or the NHR 7 group is in the para position.

[0131] Particularly preferred curing agents include those represented by the general formula (16):

Chemical formula

[0132] Although not limited, for example, 2,2-bis-[3-amino-4-(N-methylamino)phenyl]hexafluoropropane, 2,2-bis-[3-amino-4-(N-ethylamino)phenyl]hexafluoropropane, 2,2-bis-[3-amino-4-(N-propylamino)phenyl]hexafluoropropane, 2,2-bis-[3-amino-4-(N-phenylamino)phenyl]hexafluoropropane, 2,2-bis-[3-amino-4-(N-perfluorophenylamino)phenyl]hexafluoropropane, 2,2-bis-[3-amino-4-(N-benzylamino)phenyl]hexafluoropropane, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (common name: bis(aminophenol) AF), 2,2-bis(3-amino-4-mercaptophenyl)hexafluoropropane, tetraaminobenzene, bis-3,4-diaminophenylmethane, bis-3,4-diaminophenylether, 2,2-bis(3,4-diaminophenyl)hexafluoropropane, etc. can be mentioned.

[0133] The curing agent described above is excellent in mechanical strength, heat resistance, and chemical resistance, and provides a crosslinked product that is particularly excellent in heat resistance and chemical resistance with good balance.

[0134] The curing agent for the crosslinkable elastomer is preferably 0.05 to 10 parts by mass, more preferably 1 to 5 parts by mass, based on 100 parts by mass of the crosslinkable elastomer. If the curing agent is less than 0.05 parts by mass, the crosslinkable elastomer tends not to be sufficiently crosslinked, and if it exceeds 10 parts by mass, the physical properties of the crosslinked product tend to deteriorate.

[0135] The crosslinkable elastomer composition of the present invention may further contain an organic basic compound.

[0136] Examples of the organic basic compound include octadecylamine of the formula CH3(CH2) 17 -NH2; erucamide of the formula H2N-C(O)-(CH2) 11 -CH=CH-(CH2)7CH3; oleamide of the formula H2N-C(O)-(CH2)7-CH=CH-(CH2)7CH3; hexamethylenediamine of the formula H2N-(CH2)6-NH2 Formula:

Chemical formula

[0137] The crosslinkable elastomer composition of the present invention and the crosslinkable elastomer are preferably produced substantially in the absence of a metal compound as a raw material. The metal content of the crosslinkable elastomer composition is preferably 100 ppm or less, more preferably 50 ppm or less, and still more preferably 10 ppm or less. When the metal content of the crosslinkable elastomer composition is extremely low, a molded product that can be used in a semiconductor manufacturing process or a pharmaceutical manufacturing process where contamination by a metal component should be avoided can be obtained, which is preferable. The metal content can be measured by flameless atomic absorption spectrometry or high-frequency inductively coupled plasma optical emission spectrometry. The metal content in the present invention is the total metal content of Fe, Cr, Ni, Cu, Al, Na, Mg, Ca, Zn, Ba, and K. The metal content of the crosslinkable elastomer composition may be such that the total content of these metals and metals other than these metals is within the above range.

[0138] The crosslinkable elastomer composition of the present invention can be prepared by mixing the above components using a conventional processing machine for elastomers, such as an open roll, a Banbury mixer, a kneader, etc. In addition, it can also be prepared by a method using a closed mixer or a method of co-precipitation from emulsion mixing.

[0139] The method for obtaining a preform from the above composition may be a conventional method, and can be carried out by known methods such as a method of heating and compressing with a mold, a method of press-fitting into a heated mold, a method of extruding with an extruder, etc. In the case of an extruded product such as a hose or an electric wire, since the shape can be maintained even after extrusion, a preform extruded without using a crosslinking agent can be used as it is. Of course, it is also possible to use a preform that has been heat-crosslinked with steam or the like using a crosslinking agent. Also, in the case of a molded product such as an O-ring, where it is difficult to maintain the shape even after demolding in the uncrosslinked state, it can be carried out by using a preform that has been crosslinked in advance using a crosslinking agent.

[0140] When performing peroxide crosslinking, it can be carried out under the crosslinking conditions of ordinary crosslinkable elastomers. For example, by putting it into a mold and holding it at 120 to 200 °C for 1 to 60 minutes under pressure to perform press crosslinking, and then holding it in a furnace at 120 to 250 °C for 0 to 48 hours to perform oven crosslinking, a crosslinked product can be obtained.

[0141] When performing oxazole crosslinking using a crosslinking agent such as bisaminophenol, it can be carried out under the crosslinking conditions of ordinary crosslinkable elastomers. For example, by putting it into a mold and holding it at 120 to 250 °C for 1 to 60 minutes under pressure to perform press crosslinking, and then holding it in a furnace at 120 to 320 °C for 0 to 48 hours to perform oven crosslinking, a crosslinked product can be obtained. Also, a known crosslinking method for crosslinkable elastomers, for example, adding bis(aminophenol) AF, etc. to polyamine crosslinking, polyol crosslinking, peroxide crosslinking formulations and performing combined crosslinking can also be done.

[0142] Imidazole crosslinking that crosslinks carboxyl groups with bisdiaminophenyl-based crosslinking agents is most suitable for carboxyl-containing polymers having carboxyl groups other than at the terminals, and gives a crosslinked product having good physical properties at a relatively low crosslinking temperature (for example, 150 to 230 °C, preferably 170 to 200 °C).

[0143] In addition, the fluororubber molded product of the present invention has a weight loss rate of 2.5 mass% or less after O2 irradiation under the following conditions, a particle generation amount of 0.05 mass% or less, a weight loss rate of 1.8 mass% or less after NF3 plasma irradiation, a particle generation amount of 0.05 mass% or less, and a compression set of 50% or less at 300 °C for 70 hours. Note Sample: O-ring (AS-568A-214) Measurement method: (1) O2 plasma Plasma irradiation device: ICP high-density plasma device (MODEL RIE-101iPH manufactured by Samco Inc.) Irradiation conditions Gas flow rate: 16 SCCM RF output: 400 Wh Pressure: 2.66 Pa Etching time: 30 minutes Temperature: 100 °C Conditions corresponding to an etching rate of perfluoroelastomer (non - filler) of 12000 Å / min. (2) NF3 plasma Plasma irradiation device: ICP high - density plasma device (MODEL RIE - 101iPH manufactured by Samco Inc.) Irradiation conditions Gas flow rate: 16 SCCM RF output: 400 Wh Pressure: 10 Pa Etching time: 4 hours Temperature: 200 °C Conditions corresponding to an etching rate of silicon wafer thermal oxide film (SiO2) of 90 Å / min.

[0144] Such a fluororubber molded product of the present invention can be produced from the cross - linkable elastomer composition of the present invention described above.

[0145] The weight loss rate after O2 plasma irradiation is 2.5 mass% or less, preferably 1.5 mass% or less. Since the lower the weight loss rate, the better, the lower limit is not particularly limited. The particle generation amount is 0.05 mass% or less, preferably 0.03 mass% or less. Since the lower the particle generation amount, the better, the lower limit is not particularly limited. When the weight loss rate is 2.5 mass% or less, when used as a sealing material, the life against O2 plasma becomes longer and the long - term durability is improved. Also, when the particle generation amount is 0.05 mass% or less, it becomes difficult for particles to adhere to the device even when irradiated with O2 plasma, so that contamination of the device can be prevented. Further, particle adhesion to the device can be reduced and deterioration of the device manufacturing yield can be suppressed.

[0146] The weight loss rate after NF3 plasma irradiation is 1.8 mass% or less, preferably 1.5 mass% or less. Since the lower the weight loss rate, the better, the lower limit is not particularly limited. The amount of particle generation is 0.05 mass% or less, preferably 0.03 mass% or less. Since the lower the amount of particle generation, the better, the lower limit is not particularly limited. When the weight loss rate is 1.8 mass% or less, the life of the sealing material against NF3 plasma becomes longer and the long-term durability is improved. When the amount of particle generation is small, it is difficult for particles to adhere to the device even when irradiated with NF3 plasma, so that contamination of the device can be prevented. Also, particle adhesion to the device can be reduced and deterioration of the yield of device manufacturing can be suppressed.

[0147] The compression set at 300 °C for 70 hours is 50% or less, preferably 45% or less, more preferably 40% or less. When the compression set is small, the life of the sealing material becomes longer and the long-term durability is improved.

[0148] The plasma resistance to O2 and NF3 can be achieved by using specific non-oxide ceramic filler species. On the other hand, the compression set at high temperature can be achieved by oxidizing the surface of the non-oxide ceramic filler.

[0149] Such molded products can be suitably used as sealing materials for semiconductor manufacturing apparatuses that particularly require a high degree of cleanliness, especially semiconductor manufacturing apparatuses where high-density plasma irradiation is performed. Examples of the above sealing materials include O-rings, square-rings, gaskets, packings, oil seals, bearing seals, lip seals, etc. In addition, they can also be used as various polymer products used in semiconductor manufacturing apparatuses, such as diaphragms, tubes, hoses, various rubber rolls, belts, etc. Further, they can also be used as coating materials and lining materials.

[0150] Note that the semiconductor manufacturing apparatus referred to in the present invention is not particularly limited to an apparatus for manufacturing semiconductors, but broadly includes all manufacturing apparatuses used in the semiconductor field that requires a high degree of cleanliness, such as apparatuses for manufacturing liquid crystal panels and plasma panels. For example, the following can be mentioned.

[0151] (1) Etching apparatus Dry etching apparatus, plasma etching apparatus, reactive ion etching apparatus, reactive ion beam etching apparatus, sputter etching apparatus, ion beam etching apparatus Wet etching apparatus, ashing apparatus (2) Cleaning apparatus Dry etching cleaning apparatus, UV / O3 cleaning apparatus, ion beam cleaning apparatus, laser beam cleaning apparatus, plasma cleaning apparatus, gas etching cleaning apparatus, extraction cleaning apparatus, Soxhlet extraction cleaning apparatus, high-temperature high-pressure extraction cleaning apparatus, microwave extraction cleaning apparatus, supercritical extraction cleaning apparatus (3) Exposure apparatus Stepper, coater / developer (4) Polishing apparatus CMP apparatus (5) Film forming apparatus CVD apparatus, sputtering apparatus (6) Diffusion / ion implantation apparatus Oxidation diffusion apparatus, ion implantation apparatus

[0152] The molded article of the present invention exhibits excellent performance as a sealing material for, for example, a CVD apparatus, a plasma etching apparatus, a reactive ion etching apparatus, an ashing apparatus, or an excimer laser exposure machine.

Example

[0153] Next, the present invention will be described with reference to examples, but the present invention is not limited to such examples only.

[0154] Production Example 1 (Heat treatment) Silicon carbide (NM-SiC manufactured by Nanomakers Co., Ltd., average particle size 30 nm) was heat-treated in a muffle furnace at 800 °C for 1 hour in the atmosphere to obtain silicon carbide with an oxidized surface.

[0155] <Measurement of surface oxidation state> The non-oxide ceramics obtained by the surface oxidation treatment were measured by ESCA under the conditions of an X-ray source of Mg, 8 kV - 10 mA. In the silicon carbide prepared in Production Example 1, it was confirmed that 40% of SiC in the surface layer of 3 - 5 nm decreased and migrated to SiO2, and 60% remained as SiC (the ratio of the peak derived from SiO2 to the peak derived from SiC was 2:3).

[0156] Examples 1 - 5, Comparative Examples 1 - 10 According to the compounding composition described in Table 1, non-oxide ceramics and a cross-linking agent were added to a fluorine-containing elastomer (TFE / PMVE / CNVE (CF2=CFOCF2CF(CF3)OCF2CF2CN) = 59.4 / 40.1 / 0.5 (molar ratio)), and the mixture was kneaded with an open roll to prepare a cross-linkable fluororubber composition. NphAF used 2,2-bis[3-amino-4-(N-phenylamino)phenyl]hexafluoropropane. As the heat-treated silicon carbide, the one heat-treated in Production Example 1 was used. As the silicon oxide used in Comparative Example 7, 50 manufactured by Nippon Aerosil Co., Ltd. was used, and as the surface-treated silicon oxide in Comparative Examples 8 and 9, RX50 manufactured by Nippon Aerosil Co., Ltd. was used.

[0157] The fluororubber compositions obtained in Examples 1, 3, Comparative Examples 1, 3, 6 - 8, 10 were pressed at 180 °C for 30 minutes for cross-linking, and then further subjected to oven cross-linking at 290 °C for 18 hours in an oven to produce molded articles of cross-linked products with a thickness of 2 mm and molded articles of O-rings (AS-568A-214 size). Also, the fluororubber compositions obtained in Examples 2, 4, 5, Comparative Examples 2, 4, 5, 9 were pressed at 180 °C for 30 minutes for cross-linking, and then further subjected to oven cross-linking at 200 - 290 °C for 18 hours in an oven to produce molded articles of cross-linked products with a thickness of 2 mm and molded articles of O-rings (AS-568A-214 size). Using the obtained molded product, the hardness, compression set, weight loss rate after plasma irradiation, and particle generation amount were measured according to the methods shown below. The results are shown in Table 1.

[0158] <Hardness> The hardness was measured according to JIS K 6301.

[0159] <Compression Set> An O-ring (AS-568A-214) was molded, and the compression set after 70 hours and 168 hours at 300 °C was measured according to JIS K6262.

[0160] <Plasma Resistance> The molded product of the O-ring (P-24 size) was subjected to plasma irradiation treatment under the following conditions, and the weight change before and after irradiation was measured.

[0161] (1) O2 Plasma Plasma irradiation apparatus: ICP high-density plasma apparatus (MODEL RIE-101iPH manufactured by Samco Inc.) Irradiation conditions Gas flow rate: 16 SCCM RF output: 400 Wh Pressure: 2.66 Pa Etching time: 30 minutes Temperature: 100 °C Conditions corresponding to an etching rate of perfluoroelastomer (non-filler) of 12000 Å / min.

[0162] (2) NF3 Plasma Plasma irradiation apparatus: ICP high-density plasma apparatus (MODEL RIE-101iPH manufactured by Samco Inc.) Irradiation conditions Gas flow rate: 16 SCCM RF output: 400 Wh Pressure: 10 Pa Etching time: 4 hours Temperature: 200 °C Conditions corresponding to an etching rate of silicon wafer thermal oxide film (SiO2) of 90 Å / min.

[0163] An electronic analytical balance was used to measure up to 0.01 mg and round off to the nearest 0.01 mg. Three samples were used for each type, and the average value of the weight loss rate was calculated.

[0164] A film was pressed against the O-ring after plasma irradiation, and the presence or absence of transfer to the film was visually confirmed.

[0165] [Table 1]

Claims

1. A crosslinkable elastomer composition is prepared by mixing a crosslinkable elastomer and a non-oxide ceramic filler whose surface is oxidized by heat treatment, acid treatment, ozone treatment, or oxygen plasma treatment in air. Among 100% by mass of the non-oxide ceramic filler, the proportion of the filler whose surface is oxidized by 2 nm or more is 10 to 100% by mass. A method for producing a crosslinkable elastomer composition, which comprises obtaining a crosslinkable elastomer composition wherein the non-oxide ceramic filler is silicon carbide.

2. The method for producing a crosslinkable elastomer composition according to claim 1, wherein the average particle diameter of the non-oxide ceramic filler is 0.1 μm or less.

3. The method for producing a crosslinkable elastomer composition according to claim 1 or 2, wherein the crosslinkable elastomer is a copolymer of tetrafluoroethylene and perfluoro(alkyl vinyl ether).

4. A method for producing a fluororubber molded article, which comprises producing a fluororubber molded article having a compression set at 300 °C for 70 hours of 50% or less from the crosslinkable elastomer composition obtained by the production method according to any one of claims 1 to 3. O under the following conditions ２ The weight loss rate after plasma irradiation is 2.5 mass% or less, and the amount of particle generation is 0.05 mass% or less, NF ３ The weight loss rate after plasma irradiation is 1.8 mass% or less, and the amount of particle generation is 0.05 mass% or less, Sample: O-ring (AS-568A-214) Measurement method: Plasma irradiation apparatus: ICP high-density plasma apparatus (MODEL RIE-101iPH manufactured by Samco Inc.) (1) O ２ Plasma Irradiation conditions Gas flow rate: 16 SCCM RF output: 400 Wh Pressure: 2.66 Pa Etching time: 30 minutes Temperature: 100 °C Conditions corresponding to an etching rate of perfluoroelastomer (non-filler) of 12,000 Å / min. Plasma irradiation apparatus: ICP high-density plasma apparatus (MODEL RIE-101iPH manufactured by Samco Inc.) (2)NF ３ Plasma Irradiation conditions Gas flow rate: 16 SCCM RF output: 400 Wh Pressure: 10 Pa Etching time: 4 hours Temperature: 200 °C ​ Conditions where the etching rate of a silicon wafer thermal oxide film (SiO ２ ) corresponds to 90 Å / min.

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