Perfluoroelastomer composition and perfluoroelastomer crosslinked product

Abstract

To provide a perfluoroelastomer that can give a crosslinked product having excellent permanent compression set properties and excellent transparency, and a perfluoroelastomer crosslinked product having excellent permanent compression set properties and excellent transparency.SOLUTION: Provided is a perfluoroelastomer composition that contains: a nitrile-group-containing perfluoroelastomer (A); a nitrile-group-free, iodine- or bromine-containing perfluoroelastomer (B); and at least one compound (C) selected from the group consisting of inorganic nitrides and ammonia-generating compounds.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a perfluoroelastomer composition and a perfluoroelastomer crosslinked product. [Background technology]

[0002] Patent Document 1 describes a perfluoropolymer having randomly copolymerized units of tetrafluoroethylene, perfluoro(alkyl vinyl) ether, and a nitrile group-containing fluorinated cure site monomer, which further contains iodine moieties present in an amount of at least about 0.05% by weight of the perfluoropolymer.

[0003] Patent Document 2 describes a curable composition comprising a perfluoroelastomer and a curing agent, in which the perfluoroelastomer comprises copolymerized units of (1) tetrafluoroethylene, (2) a perfluorovinyl ether selected from the group consisting of perfluoro(alkyl vinyl) ethers, perfluoro(alkoxy vinyl) ethers, and mixtures thereof, and (3) a cure site monomer selected from the group consisting of nitrile-containing fluorinated olefins and nitrile-containing fluorinated vinyl ethers, and the curing agent is selected from the group consisting of diaminobisphenol AF, organic peroxides, and compounds other than ammonium salts of organic or inorganic acids that decompose at temperatures of 40°C to 330°C to generate ammonia. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 05-500070 [Patent Document 2] Special Publication No. 2004-532902 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a perfluoroelastomer composition capable of giving a crosslinked product having excellent compression set properties and excellent transparency, and a perfluoroelastomer crosslinked product having excellent compression set properties and excellent transparency. [Means for solving the problem]

[0006] According to the present disclosure, there is provided a perfluoroelastomer composition containing a nitrile group-containing perfluoroelastomer (A), an iodine- or bromine-containing perfluoroelastomer not containing a nitrile group (B), and at least one compound (C) selected from the group consisting of inorganic nitrides and ammonia-generating compounds.

[0007] In the perfluoroelastomer composition of the present disclosure, the content of the iodine- or bromine-containing perfluoroelastomer (B) is preferably 0.5 to 10 parts by mass based on 100 parts by mass of the nitrile group-containing perfluoroelastomer (A). In the perfluoroelastomer composition of the present disclosure, compound (C) is preferably silicon nitride.

[0008] The present disclosure also provides a perfluoroelastomer crosslinked product obtained by crosslinking the above perfluoroelastomer composition.

[0009] Furthermore, the present disclosure provides a perfluoroelastomer crosslinked product having a haze value of 95% or less and a compression set of 25 to 40%.

[0010] The perfluoroelastomer crosslinked product of the present disclosure preferably has a total light transmittance of 85% or more. The perfluoroelastomer crosslinked product of the present disclosure preferably contains a triazine ring. The perfluoroelastomer crosslinked product of the present disclosure preferably contains iodine atoms or bromine atoms. The perfluoroelastomer crosslinked product of the present disclosure preferably contains silicon atoms. Effect of the Invention

[0011] According to the present disclosure, it is possible to provide a perfluoroelastomer composition that can give a crosslinked product having excellent compression set properties and excellent transparency, and a perfluoroelastomer crosslinked product having excellent compression set properties and excellent transparency. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

[0013] The perfluoroelastomer composition of the present disclosure contains a nitrile group-containing perfluoroelastomer (A), a nitrile group-free iodine- or bromine-containing perfluoroelastomer (B), and at least one compound (C) selected from the group consisting of inorganic nitrides and ammonia-generating compounds.

[0014] Patent Document 1 describes that the above-mentioned perfluoropolymer reacts with a peroxide curing agent and a crosslinking coagent to produce a unique polymer network structure in which crosslinks occur both at random points along the polymer chain and at the chain ends. It further describes that such perfluoropolymer has excellent strength and compression set properties, as well as good processing properties.

[0015] However, when the perfluoropolymer described in Patent Document 1 is crosslinked using a peroxide curing agent and a crosslinking auxiliary, there is a problem that excellent compression set properties cannot be obtained.

[0016] Patent Document 2 describes that it is beneficial to have a perfluoroelastomer article that is translucent or transparent, light-colored or colorless, and contains a very low amount of metal while maintaining good tensile properties and low compression set.However, the crosslinked product obtained from the curable composition described in Patent Document 2 also has a problem that it cannot fully achieve both compression set property and transparency.

[0017] As a result of intensive research into the means for solving these problems, it was found that by adding a nitrile-group-free iodine- or bromine-containing perfluoroelastomer (B) and a compound (C) to a nitrile-group-containing perfluoroelastomer (A), the transparency of the crosslinked product obtained can be improved without significantly deteriorating the compression set properties of the crosslinked product obtained. The reason for this is not clear, but it is presumed that the action of the compound (C) causes the nitrile-group-containing perfluoroelastomer (A) to form a crosslinked perfluoroelastomer, while the iodine- or bromine-containing perfluoroelastomer (B) can move freely in the crosslinked product without crosslinking, thereby filling in slight defects that cause cloudiness of the crosslinked product. The perfluoroelastomer composition and the perfluoroelastomer crosslinked product of the present disclosure were completed based on such findings.

[0018] The perfluoroelastomer composition of the present disclosure contains at least perfluoroelastomers (A) and (B) as perfluoroelastomers. In the present disclosure, the perfluoroelastomer is a fluoropolymer having a perfluoromonomer unit content of 90 mol% or more, preferably 91 mol% or more, relative to the total polymerized units, a glass transition temperature of 20°C or less, a melting peak (ΔH) of 4.5 J / g or less, and a concentration of fluorine atoms contained in the fluoropolymer of 71 mass% or more, preferably 71.5 mass% or more. In the present disclosure, the concentration of fluorine atoms contained in the fluoropolymer is calculated from the type and content of each monomer constituting the fluoropolymer to determine the concentration of fluorine atoms (mass%) contained in the fluoropolymer.

[0019] In the present disclosure, a perfluoromonomer is a monomer that does not contain a carbon atom-hydrogen atom bond in the molecule. The perfluoromonomer may be a monomer in which some of the fluorine atoms bonded to the carbon atom are replaced with chlorine atoms, in addition to carbon atoms and fluorine atoms, and may also have nitrogen atoms, oxygen atoms, sulfur atoms, phosphorus atoms, boron atoms, or silicon atoms in addition to carbon atoms. The perfluoromonomer is preferably a monomer in which all hydrogen atoms are replaced with fluorine atoms. The perfluoromonomer does not include a monomer that provides a crosslinking site.

[0020] The monomer that provides a crosslinking site is a monomer (cure site monomer) having a crosslinkable group that provides a crosslinking site for forming a crosslink to the perfluoroelastomer.

[0021] In the present disclosure, the content of each monomer constituting the perfluoroelastomer can be calculated by an appropriate combination of NMR, FT-IR, elemental analysis, X-ray fluorescence analysis, and other known methods depending on the type of monomer.

[0022] Perfluoromonomers that provide perfluoromonomer units constituting the perfluoroelastomer include: Tetrafluoroethylene (TFE), Hexafluoropropylene (HFP), General formula (13): CF2=CF-ORf 13 (In the formula, Rf 13 represents a perfluoroalkyl group having 1 to 8 carbon atoms; General formula (14): CF2=CFOCF2ORf 14 (In the formula, Rf 14 is a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, a cyclic perfluoroalkyl group having 5 to 6 carbon atoms, or a linear or branched perfluorooxyalkyl group having 2 to 6 carbon atoms and containing 1 to 3 oxygen atoms), and General formula (15): CF2=CFO(CF2CF(Y 15 )O) m (CF2) n F (In the formula, Y 15 represents a fluorine atom or a trifluoromethyl group; m is an integer of 1 to 4; and n is an integer of 1 to 4. At least one selected from the group consisting of is preferred.

[0023] Each component contained in the perfluoroelastomer composition of the present disclosure will now be described in more detail.

[0024] (Nitrile group-containing perfluoroelastomer (A)) The perfluoroelastomer (A) contains a nitrile group (-CN group). The nitrile group-containing perfluoroelastomer (A) can be crosslinked by forming a triazine ring through cyclotrimerization of the nitrile group, and can impart excellent compression set properties and heat resistance to the crosslinked product.

[0025] The nitrile group-containing perfluoroelastomer (A) preferably has a nitrile group (-CN group) at the main chain terminal and / or in a side chain.

[0026] The nitrile group-containing perfluoroelastomer (A) preferably contains a monomer unit having a nitrile group. The monomer having a nitrile group is preferably: Formula:CX 4 2=CX 5 R f 2 -CN (In the formula, X 4 , X 5 are each independently H, F or an alkyl group having 1 to 5 carbon atoms, and R f 2 is a linear or branched alkylene group or oxyalkylene group in which some or all of the hydrogen atoms may be substituted with fluorine atoms, which may have one or more ether-bonded oxygen atoms and which may have an aromatic ring.

[0027] Examples of monomers having a nitrile group include: Formula:CY 1 2=CY 1 (CF2) n -CN (In the formula, Y 1 are each independently a hydrogen atom or a fluorine atom, and n is an integer of 1 to 8. Formula: CF2=CFCF2Rf 8 -CN (In the formula, Rf 8 Ha-(OCF2) n -or-(OCF(CF3)) n -, and n is an integer from 0 to 5. Formula: CF2 = CFCF2(OCF(CF3)CF2) m (OCH2CF2CF2) n OCH2CF2-CN (In the formula, m is an integer of 0 to 5, and n is an integer of 0 to 5.) Formula: CF2=CFCF2(OCH2CF2CF2) m (OCF(CF3)CF2) n OCF(CF3)-CN (In the formula, m is an integer of 0 to 5, and n is an integer of 0 to 5.) Formula: CF2 = CF(OCF2CF(CF3))m O(CF2) n -CN (In the formula, m is an integer of 0 to 5, and n is an integer of 1 to 8.) Formula: CF2 = CF(OCF2CF(CF3)) m -CN (wherein m is an integer of 1 to 5). Formula: CF2 = CFOCF2(CF(CF3)OCF2) n CF(-CN)CF3 (wherein n is an integer of 1 to 4). Formula: CF2 = CFO(CF2) n OCF(CF3)-CN (wherein n is an integer of 2 to 5). Formula: CF2 = CFO(CF2) n -(C6H4)-CN (wherein n is an integer of 1 to 6). Formula: CF2 = CF(OCF2CF(CF3)) n OCF2CF(CF3)-CN (wherein n is an integer of 1 to 2). Formula: CH2=CFCF2O(CF(CF3)CF2O) n CF(CF3)-CN (wherein n is an integer of 0 to 5). Formula: CF2 = CFO(CF2CF(CF3)O) m (CF2) n -CN (In the formula, m is an integer of 0 to 5, and n is an integer of 1 to 3.) Formula: CH2=CFCF2OCF(CF3)OCF(CF3)-CN Formula:CH2=CFCF2OCH2CF2-CN Formula: CF2 = CFO(CF2CF(CF3)O) m CF2CF(CF3)-CN (wherein m is an integer of 0 or more) Formula: CF2 = CFOCF(CF3)CF2O(CF2) n -CN (wherein n is an integer of 1 or more) Formula: CF2=CFOCF2OCF2CF(CF3)OCF2-CN These can be used alone or in any combination.

[0028] Among the monomers having a nitrile group (-CN group), there are Formula: CF2 = CF(OCF2CF(CF3)) m O(CF2) n -CN (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8), and CF2=CFOCF2CF(CF3)OCF2CF2CN is more preferred.

[0029] The nitrile group-containing perfluoroelastomer (A) may be a copolymer of TFE / fluoromonomer represented by general formula (13), (14) or (15) / monomer having a nitrile group. In this case, the content of the monomer unit having a nitrile group may be 0.1 to 5 mol % or 0.3 to 3 mol % based on the total amount of the TFE unit and the fluoromonomer unit represented by general formula (13), (14) or (15) from the viewpoint of good crosslinking properties and heat resistance.

[0030] When the nitrile group-containing perfluoroelastomer (A) is a copolymer of TFE / perfluoro(methyl vinyl ether) (PMVE) / a monomer having a nitrile group, the composition (mol %) of the nitrile group-containing perfluoroelastomer (A) is preferably 45-89.9 / 10-54.9 / 0.01-4, more preferably 55-77.9 / 20-49.9 / 0.1-3.5, still more preferably 55-69.8 / 30-44.8 / 0.2-3, and most preferably 55.3-69.5 / 30.3-44.5 / 0.2-2.8.

[0031] When the nitrile group-containing perfluoroelastomer (A) is a copolymer of TFE / fluoromonomer having 4 to 12 carbon atoms represented by general formula (13), (14) or (15) / monomer having a nitrile group, the composition (mol %) of the nitrile group-containing perfluoroelastomer (A) is preferably 50-89.9 / 10-49.9 / 0.01-4, more preferably 60-87.9 / 12-39.9 / 0.1-3.5, still more preferably 65-84.8 / 15-34.8 / 0.2-3, and most preferably 66-84.3 / 15.5-33.8 / 0.2-2.8. Outside these composition ranges, the rubber elastic properties are lost and the properties tend to become more like those of a resin.

[0032] The nitrile group-containing perfluoroelastomer (A) is preferably at least one selected from the group consisting of a TFE / fluoromonomer represented by general formula (15) / monomer copolymer having a nitrile group and a TFE / fluoromonomer represented by general formula (13) / monomer copolymer having a nitrile group.

[0033] The nitrile group-containing perfluoroelastomer (A) may have polar end groups. By end groups is meant any group present on the polymer backbone or any long or short end present. Polar end groups include carboxylate (-COO - ) group or sulfonate (-OSO3 - ) group, and non-ionic groups such as alcohol (-CH2OH), acyl fluoride (-COF), and amide (-CONH2). Polar end groups can be introduced into elastomers by using inorganic peroxides as polymerization initiators when producing perfluoroelastomers by polymerizing monomers. The presence or absence of polar end groups can be confirmed by Fourier transform infrared spectroscopy (FTIR).

[0034] The nitrile group-containing perfluoroelastomer (A) has a glass transition temperature of preferably −70° C. or higher, more preferably −60° C. or higher, and even more preferably −50° C. or higher, from the viewpoint of excellent compression set characteristics at high temperatures. Also, from the viewpoint of good cold resistance, the glass transition temperature is preferably 5° C. or lower, more preferably 0° C. or lower, and even more preferably −3° C. or lower.

[0035] The glass transition temperature can be determined by obtaining a DSC curve using a differential scanning calorimeter (DSC822e, manufactured by Mettler Toledo) by heating 10 mg of a sample at a rate of 10°C / min, and by determining the temperature that indicates the midpoint between the two intersection points of an extension of the baseline before and after the second-order transition of the DSC curve and a tangent to the inflection point of the DSC curve.

[0036] The nitrile group-containing perfluoroelastomer (A) preferably has a Mooney viscosity ML(1+20) at 170°C of 30 or more, more preferably 40 or more, and even more preferably 50 or more, in terms of good heat resistance. Also, in terms of good processability, it is preferably 150 or less, more preferably 120 or less, and even more preferably 110 or less.

[0037] The Mooney viscosity can be measured at 170° C. in accordance with JIS K6300 using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES.

[0038] The nitrile group-containing perfluoroelastomer (A) can be produced by a conventional method.

[0039] (Iodine- or bromine-containing perfluoroelastomer (B) not containing nitrile groups) The perfluoroelastomer (B) contains iodine or bromine atoms. The perfluoroelastomer (B) does not contain a nitrile group, and in this respect it is different from the perfluoroelastomer (A). The perfluoroelastomer (B) exists in the crosslinked product without crosslinking even in the presence of the compound (C), and is presumed to impart excellent transparency to the crosslinked product without impairing the excellent compression set property of the crosslinked product. Furthermore, the iodine- or bromine-containing perfluoroelastomer (B) does not volatilize upon heating and continues to exist in the crosslinked product, and is also excellent in compatibility with the nitrile group-containing perfluoroelastomer (A), so it is presumed to be able to impart excellent compression set property and excellent transparency to the crosslinked product. Moreover, the iodine- or bromine-containing perfluoroelastomer (B) can be produced by iodine transfer polymerization, so that the molecular weight can be easily adjusted. Therefore, since it is possible to easily produce an elastomer (B) having an appropriate molecular weight according to the physical properties of the nitrile group-containing perfluoroelastomer (A), the use of the elastomer (B) is advantageous in that it is possible to easily improve the transparency while maintaining the compression set properties of the crosslinked product.

[0040] The iodine- or bromine-containing perfluoroelastomer (B) preferably has an iodine atom or a bromine atom at the main chain terminal and / or in a side chain.

[0041] The iodine- or bromine-containing perfluoroelastomer (B) is preferably at least one selected from the group consisting of perfluoroelastomers containing a monomer unit having an iodine atom or a bromine atom, perfluoroelastomers having an iodine atom or a bromine atom at a main chain terminal, and perfluoroelastomers having an iodine atom or a bromine atom at a main chain terminal and containing a monomer unit having an iodine atom or a bromine atom.

[0042] Examples of the monomer having an iodine atom or a bromine atom include: Formula:CX 4 2=CX 5 R f2 -X (In the formula, X 4 , X 5 are each independently H, F or an alkyl group having 1 to 5 carbon atoms, and R f 2 is a linear or branched alkylene group or oxyalkylene group which may have one or more ether-bonded oxygen atoms and which may have an aromatic ring, in which some or all of the hydrogen atoms may be substituted with fluorine atoms, and X is an iodine atom or a bromine atom).

[0043] Examples of the monomer having an iodine atom or a bromine atom include Formula:CX 16 2=CX 16 -Rf 16 CHR 16 X (In the formula, X 16 Each independently represents a hydrogen atom, a fluorine atom, or CH3, Rf 16 represents a fluoroalkylene group, a perfluoroalkylene group, a fluoro(poly)oxyalkylene group or a perfluoro(poly)oxyalkylene group; R 16 is a hydrogen atom or CH3, and X is an iodine atom or a bromine atom), Formula:CX 16 2=CX 16 -Rf 17 X (In the formula, X 16 Each independently represents a hydrogen atom, a fluorine atom, or CH3, Rf 17 is a fluoroalkylene group, a perfluoroalkylene group, a fluoro(poly)oxyalkylene group or a perfluoro(poly)oxyalkylene group, and X is an iodine atom or a bromine atom, Formula: CF2 = CFO(CF2CF(CF3)O) m (CF2) n -X (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, and X is an iodine atom, a bromine atom, or -CHI), Formula: CH2=CFCF2O(CF(CF3)CF2O) m (CF(CF3)) n -X (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, and X is an iodine atom or a bromine atom), and the like, which can be used alone or in any combination.

[0044] X 16 is preferably a fluorine atom. 16 and Rf 17 R is preferably a perfluoroalkylene group having 1 to 5 carbon atoms. 16 is preferably a hydrogen atom.

[0045] The monomer having an iodine atom or a bromine atom is preferably at least one selected from the group consisting of CF2=CFOCF2CF(CF3)OCF2CF2CH2I, CF2=CFOCF2CF2CH2I, and CH2=CHCF2CF2I, and more preferably CF2=CFOCF2CF2CH2I.

[0046] A perfluoroelastomer having an iodine atom or a bromine atom at the main chain end can be produced by using an iodine compound or a bromine compound as a chain transfer agent when producing a perfluoroelastomer by polymerizing a monomer. An example of a polymerization method using an iodine compound or a bromine compound is a method in which emulsion polymerization is carried out in an aqueous medium under pressure in the presence of an iodine compound or a bromine compound in a substantially oxygen-free state (iodine transfer polymerization method). Representative examples of the iodine compound or bromine compound that can be used include compounds represented by the general formula: R 21 I x Br y (In the formula, x and y are each an integer of 0 to 2, and 1≦x+y≦2 is satisfied; R 21is 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, which may contain an oxygen atom).

[0047] Examples of iodine compounds and bromine compounds include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 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, BrCF Examples of the iodoperfluoroalkyl group include 2CFClBr, 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-substituted benzene, diiodomonobromo-substituted benzene, and (2-iodoethyl) and (2-bromoethyl)-substituted benzene. These compounds may be used alone or in combination with each other.

[0048] Among these, it is preferable to use 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane in terms of polymerization reactivity, crosslinking reactivity, availability, and the like.

[0049] The content of iodine atoms and bromine atoms in the iodine- or bromine-containing perfluoroelastomer (B) is preferably 0.001 to 10% by mass, more preferably 0.01% by mass or more, even more preferably 0.1% by mass or more, and more preferably 5% by mass or less. If the content of iodine atoms and bromine atoms is too low, the haze value becomes large, and it may be difficult to obtain a crosslinked product that exhibits excellent transparency. The content of iodine atoms and bromine atoms can be measured by elemental analysis.

[0050] The iodine- or bromine-containing perfluoroelastomer (B) is preferably at least one selected from the group consisting of iodine- or bromine-containing perfluoroelastomer (B) containing a TFE unit, for example, a TFE / fluoromonomer copolymer represented by general formula (13), (14) or (15), and a TFE / fluoromonomer copolymer represented by general formula (13), (14) or (15) / monomer having an iodine atom or a bromine atom.

[0051] When the iodine- or bromine-containing perfluoroelastomer (B) is a TFE / perfluoro(methyl vinyl ether) (PMVE) copolymer, the composition (mol %) of the iodine- or bromine-containing perfluoroelastomer (B) is preferably 45-90 / 10-55, more preferably 55-80 / 20-45, further preferably 55-70 / 30-45, and most preferably 56-69.5 / 30.5-44.

[0052] When the iodine- or bromine-containing perfluoroelastomer (B) is a copolymer of TFE / PMVE / a monomer having an iodine atom or a bromine atom, the composition (mol %) of the iodine- or bromine-containing perfluoroelastomer (B) is preferably 45-89.9 / 10-54.9 / 0.01-4, more preferably 55-77.9 / 20-49.9 / 0.01-3.5, still more preferably 55-69.8 / 30-44.8 / 0.03-3.0, and most preferably 55.3-69.5 / 30.3-44.5 / 0.05-2.5.

[0053] When the iodine- or bromine-containing perfluoroelastomer (B) is a TFE / fluoromonomer copolymer having 4 to 12 carbon atoms and represented by general formula (13), (14) or (15), the composition (mol %) of the iodine- or bromine-containing perfluoroelastomer (B) is preferably 50-90 / 10-50, more preferably 60-88 / 12-40, still more preferably 65-85 / 15-35, and most preferably 66-84 / 16-34.

[0054] When the iodine- or bromine-containing perfluoroelastomer (B) is a copolymer of TFE / fluoromonomer having 4 to 12 carbon atoms represented by general formula (13), (14) or (15) / monomer having an iodine atom or a bromine atom, the composition (mol %) of the iodine- or bromine-containing perfluoroelastomer (B) is preferably 50-89.9 / 10-49.9 / 0.01-4, more preferably 60-87.9 / 12-39.9 / 0.1-3.5, still more preferably 65-84.8 / 15-34.8 / 0.2-3.0, and most preferably 66-84.3 / 15.5-33.8 / 0.2-2.0. Outside these composition ranges, the rubber elastic properties are lost and the properties tend to become more like those of a resin.

[0055] The iodine- or bromine-containing perfluoroelastomer (B) is preferably at least one selected from the group consisting of TFE / fluoromonomer copolymer represented by general formula (13), TFE / fluoromonomer copolymer represented by general formula (13) / monomer having an iodine atom or a bromine atom, TFE / fluoromonomer copolymer represented by general formula (15), and TFE / fluoromonomer copolymer represented by general formula (15) / monomer having an iodine atom or a bromine atom.

[0056] The iodine- or bromine-containing perfluoroelastomer (B) has a glass transition temperature of preferably −70° C. or higher, more preferably −60° C. or higher, and even more preferably −50° C. or higher, from the viewpoint of excellent compression set characteristics at high temperatures. Also, from the viewpoint of good cold resistance, the glass transition temperature is preferably 5° C. or lower, more preferably 0° C. or lower, and even more preferably −3° C. or lower.

[0057] The glass transition temperature can be determined by obtaining a DSC curve using a differential scanning calorimeter (DSC822e, manufactured by Mettler Toledo) by heating 10 mg of a sample at a rate of 10°C / min, and by determining the temperature that indicates the midpoint between the two intersection points of an extension of the baseline before and after the second-order transition of the DSC curve and a tangent to the inflection point of the DSC curve.

[0058] The iodine- or bromine-containing perfluoroelastomer (B) preferably has a Mooney viscosity ML(1+10) at 100° C. of 10 or more, more preferably 20 or more, and even more preferably 25 or more, in terms of good heat resistance. Also, in terms of good processability, it is preferably 120 or less, more preferably 100 or less, and even more preferably 80 or less.

[0059] The Mooney viscosity can be measured at 100° C. in accordance with JIS K6300 using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES.

[0060] The perfluoroelastomer (B) can be produced by a conventional method.

[0061] The content of the iodine- or bromine-containing perfluoroelastomer (B) is preferably 0.5 to 10 parts by mass, more preferably 1.0 part by mass or more, even more preferably 2.0 parts by mass or more, particularly preferably 3.0 parts by mass or more, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, based on 100 parts by mass of the nitrile group-containing perfluoroelastomer (A). If the content of the iodine- or bromine-containing perfluoroelastomer (B) is too high, a crosslinked product exhibiting excellent compression set properties may not be obtained, and crushing (cracks) may occur during compression. If the content of the iodine- or bromine-containing perfluoroelastomer (B) is too low, the haze value may be large, and a crosslinked product exhibiting excellent transparency may not be obtained.

[0062] (Compound (C)) The perfluoroelastomer composition of the present disclosure contains at least one compound (C) selected from the group consisting of inorganic nitrides and ammonia-generating compounds. By containing the compound (C), the nitrile groups of the nitrile group-containing perfluoroelastomer (A) can be cyclized and trimerized to form triazine rings, thereby crosslinking the nitrile group-containing perfluoroelastomer (A). On the other hand, the iodine- or bromine-containing perfluoroelastomer (B) that does not contain a nitrile group is not crosslinked even in the presence of the compound (C), and exists in an uncrosslinked state in the obtained crosslinked product. It is presumed that the iodine- or bromine-containing perfluoroelastomer (B) that exists in an uncrosslinked state in the obtained crosslinked product imparts excellent transparency to the crosslinked product without impairing the excellent compression set properties of the crosslinked product.

[0063] Examples of inorganic nitrides include, but are not limited to, silicon nitride (Si3N4), lithium nitride, titanium nitride, aluminum nitride, boron nitride, vanadium nitride, zirconium nitride, etc. Among these, silicon nitride is preferred because nano-sized particles can be supplied.

[0064] As the compound that generates ammonia, a compound that generates ammonia at 40 to 330°C is preferable.

[0065] The ammonia-generating compound is preferably urea or its derivatives, or an ammonium salt, more preferably urea or an ammonium salt, and even more preferably urea. The ammonium salt may be an organic ammonium salt or an inorganic ammonium salt. The ammonia-generating compound may also be one that reacts with a small amount of water to generate ammonia.

[0066] Examples of urea derivatives include biurea, thiourea, urea hydrochloride, and biuret.

[0067] Examples of the organic ammonium salt include ammonium salts of non-fluorine-based carboxylic acids or sulfonic acids, such as ammonium benzoate, ammonium adipate, and ammonium phthalate.

[0068] Examples of inorganic ammonium salts include the compounds described in JP-A-9-111081, such as ammonium sulfate, ammonium carbonate, ammonium nitrate, and ammonium phosphate.

[0069] Further, examples of the ammonia generating compound include acetaldehyde ammonia, hexamethylenetetramine, formamidine, formamidine hydrochloride, formamidine acetate, t-butyl carbamate, benzyl carbamate, and phthalamide.

[0070] As the compound (C), at least one selected from the group consisting of urea, urea derivatives, and inorganic nitrides is preferable, inorganic nitrides are more preferable, and silicon nitride is even more preferable, because excellent compression set properties and excellent transparency can be simultaneously achieved at a high level.

[0071] The content of the compound (C) is preferably 0.05 to 10 parts by mass, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, more preferably 5 parts by mass or less, even more preferably 3 parts by mass or less, particularly preferably 1.0 parts by mass or less, and most preferably 0.5 parts by mass or less, based on 100 parts by mass of the nitrile group-containing perfluoroelastomer (A). If the content of the compound (C) is too high, scorching may occur, and if the content of the compound (C) is too low, crosslinking of the nitrile group-containing perfluoroelastomer (A) may be insufficient, and a crosslinked product showing excellent compression set properties may not be obtained.

[0072] (Other Ingredients) The perfluoroelastomer composition may further contain a filler. In one embodiment of the perfluoroelastomer composition, from the viewpoint of further improving the transparency of the obtained crosslinked product, the composition does not substantially contain a filler, for example, contains less than 0.01 parts by mass of a filler per 100 parts by mass of the nitrile group-containing perfluoroelastomer (A).

[0073] Examples of the filler include imide-based fillers having an imide structure, such as polyimide, polyamideimide, and polyetherimide; organic fillers made of engineering plastics, such as polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyetherketone, and polyoxybenzoate; metal oxide fillers, such as silicon oxide, aluminum oxide, and yttrium oxide; metal carbides, such as silicon carbide and aluminum carbide; metal nitride fillers, such as aluminum nitride; and inorganic fillers, such as carbon black, aluminum fluoride, and carbon fluoride.

[0074] Among these, carbon black, aluminum oxide, silicon oxide, yttrium oxide, silicon carbide, polyimide, and carbon fluoride are preferred from the viewpoint of shielding effect against various plasmas.

[0075] The above fillers may be used alone or in combination of two or more.

[0076] In particular, in fields where high purity and non-staining properties are not required, ordinary additives that are blended into compositions, such as processing aids, plasticizers, colorants, etc., may be blended as necessary, and one or more commonly used crosslinking agents or crosslinking assistants different from those described above may also be blended.

[0077] The composition may contain an organic basic compound. The organic basic compound may be a compound represented by the formula: CH3(CH2) 17 -Octadecylamine in NH2; Formula:H2N-C(O)-(CH2) 11 -CH=CH-(CH2)7CH3 erucamide; Oleamide of formula: H2N-C(O)-(CH2)7-CH=CH-(CH2)7CH3; Hexamethylenediamine of formula H2N-(CH2)6-NH2 formula: [ka] Examples of such aryl ethers include 1,8-diazabicycloundec-7-ene (DBU).

[0078] The perfluoroelastomer composition can be prepared by mixing the above-mentioned components using a general polymer processing machine, such as an open roll, a Banbury mixer, a kneader, etc. Alternatively, it can be prepared by a method using an internal mixer. The perfluoroelastomer composition can be suitably used as a molding material for obtaining a crosslinked product by crosslinking molding.

[0079] (Crosslinked product) By crosslinking the perfluoroelastomer composition, a perfluoroelastomer crosslinked product can be obtained. The perfluoroelastomer crosslinked product of the present disclosure has excellent compression set properties and excellent transparency.

[0080] The perfluoroelastomer crosslinked product according to one embodiment has a haze value of 95% or less and a compression set of 25 to 40%. The perfluoroelastomer crosslinked product according to this embodiment exhibits excellent compression set properties even at high temperatures and also exhibits excellent transparency, and can therefore be used as a sealing material in fields that require excellent heat resistance and high cleanliness. The perfluoroelastomer crosslinked product according to this embodiment is preferably obtained by crosslinking the perfluoroelastomer composition of the present disclosure.

[0081] The haze value of the perfluoroelastomer crosslinked product is preferably 95% or less, more preferably 90% or less, and even more preferably 80% or less. The lower the haze value of the perfluoroelastomer crosslinked product, the more preferable it is, but the lower limit of the haze value may be, for example, 50% or more. The haze value can be measured for a crosslinked product of any thickness in accordance with ASTM D1003.

[0082] The compression set of the perfluoroelastomer crosslinked product is preferably 50% or less, more preferably 40% or less, and further preferably 30% or less.

[0083] The compression set of the crosslinked perfluoroelastomer is measured by leaving the crosslinked product at 300°C for 72 hours at a compression rate of 25%. The compression set can be calculated by leaving the crosslinked product compressed at 25% compression rate at 300°C for 72 hours, releasing the compression, leaving the product at 23°C for 30 minutes, and then measuring the thickness of the crosslinked product before and after compression.

[0084] The total light transmittance of the perfluoroelastomer crosslinked product is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more. The higher the total light transmittance of the perfluoroelastomer crosslinked product, the more preferable it is, but the upper limit of the total light transmittance may be, for example, 95% or less. The total light transmittance can be measured for a crosslinked product of any thickness in accordance with ASTM D1003.

[0085] The perfluoroelastomer crosslinked product preferably contains a triazine ring. The triazine ring imparts excellent high-temperature compression set properties to the crosslinked product without impairing the transparency of the crosslinked product. The presence or absence of a triazine ring in the perfluoroelastomer crosslinked product can be confirmed by Fourier transform infrared spectroscopy (FT-IR).

[0086] The content of triazine rings in the perfluoroelastomer crosslinked product is preferably 0.04 or more, more preferably 0.05 or more. In the present disclosure, the content of triazine rings in the perfluoroelastomer crosslinked product is represented by the ratio of the content of triazine rings to the content of C-F bonds in the perfluoroelastomer crosslinked product. The content of triazine rings in the perfluoroelastomer crosslinked product can be measured by Fourier transform infrared spectroscopy (FT-IR). The infrared spectrum of the crosslinked product is obtained using a Fourier transform infrared spectrophotometer (FT-IR), and the overtone vibration peaks of the C-F bonds that appear in the infrared spectrum (2360 cm -1 ) versus the triazine ring peak (1555 cm -1 The triazine ring content can be determined by calculating the absorbance ratio (A1555 / A2360) of these two compounds.

[0087] The perfluoroelastomer crosslinked product preferably contains iodine atoms or bromine atoms. The iodine atoms or bromine atoms impart excellent transparency to the crosslinked product without impairing the compression set properties of the crosslinked product. The presence or absence of iodine atoms or bromine atoms in the perfluoroelastomer crosslinked product can be confirmed by elemental analysis by ion chromatography of the ashed product obtained by ashing the crosslinked product.

[0088] The content of iodine atoms and bromine atoms in the perfluoroelastomer crosslinked product is preferably 0.0001% by mass or more, more preferably 0.0005% by mass or more, even more preferably 0.0008% by mass or more, preferably 0.010% by mass or less, more preferably 0.005% by mass or less, and even more preferably 0.002% by mass or less. The content of iodine atoms and bromine atoms can be measured by elemental analysis using ion chromatography of the ashed product obtained by ashing the crosslinked product.

[0089] The perfluoroelastomer crosslinked product preferably contains silicon atoms. Silicon atoms impart both excellent compression set properties and excellent transparency to the crosslinked product at high levels. The presence or absence of silicon atoms in the perfluoroelastomer crosslinked product can be confirmed by energy dispersive X-ray analysis (EDX).

[0090] The content of silicon atoms in the perfluoroelastomer crosslinked product is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and preferably 1.0% by mass or less, and further preferably 0.5% by mass or less. The content of silicon atoms can be measured by energy dispersive X-ray analysis (EDX).

[0091] The method for obtaining a perfluoroelastomer crosslinked product from a perfluoroelastomer composition includes a method of obtaining a preform by molding the perfluoroelastomer composition as a molding material, and then crosslinking the preform. The method for obtaining a preform from a perfluoroelastomer composition may be a conventional method, and may be a known method such as a method of heating and compressing in a mold, a method of pressing into a heated mold, or a method of extruding with an extruder. In the case of extrusion products such as hoses and electric wires, a perfluoroelastomer crosslinked product can be obtained by performing heat crosslinking with steam or the like after extrusion.

[0092] The crosslinking can be carried out in the order of primary crosslinking and secondary crosslinking. The primary crosslinking is preferably carried out at 150 to 250° C. for 5 to 120 minutes, and more preferably at 170 to 200° C. for 5 to 60 minutes. As the crosslinking means, a known crosslinking means may be used, and an example of the crosslinking means is press crosslinking.

[0093] The secondary crosslinking is preferably carried out at 180 to 320° C. for 2 to 48 hours, more preferably at 200 to 310° C. for 5 to 24 hours. The temperature may be changed within this temperature range. As the crosslinking means, a known crosslinking means may be used, for example, oven crosslinking.

[0094] The perfluoroelastomer crosslinked product of the present disclosure can be suitably used as a seal material for semiconductor manufacturing equipment that requires heat resistance, particularly for semiconductor manufacturing equipment that is exposed to high-density plasma. Examples of the seal material include O-rings, square rings, gaskets, packing, oil seals, bearing seals, and lip seals.

[0095] In addition, it can be used for various polymer products used in semiconductor manufacturing equipment, such as diaphragms, tubes, hoses, various rubber rolls, belts, etc. It can also be used as a coating material or a lining material.

[0096] It should be noted that the semiconductor manufacturing equipment referred to in this disclosure is not limited to equipment specifically for manufacturing semiconductors, but broadly includes all manufacturing equipment used in the semiconductor field that requires a high degree of cleanliness, such as equipment for manufacturing liquid crystal panels and plasma panels, and examples of such equipment include the following:

[0097] (1) Etching equipment Dry Etching Equipment Plasma Etching Equipment Reactive Ion Etching Equipment Reactive Ion Beam Etching Equipment Sputter Etching Equipment Ion Beam Etching Equipment Wet Etching Equipment Ashing device (2) Cleaning equipment: Dry etching cleaning equipment UV / O3 cleaning equipment Ion Beam Cleaning Equipment Laser Beam Cleaning Equipment Plasma Cleaning Equipment Gas Etching Cleaning Equipment Extraction and Cleaning Equipment Soxhlet Extraction and Cleaning Apparatus High-temperature and high-pressure extraction and cleaning equipment Microwave Extraction Cleaning Equipment Supercritical Extraction Cleaning Equipment (3) Exposure equipment Stepper Coater Developer (4) Polishing equipment CMP equipment (5) Film deposition equipment CVD equipment Sputtering Equipment (6) Diffusion and ion implantation equipment Oxidation Diffusion Device Ion implantation equipment

[0098] The perfluoroelastomer crosslinked product of the present disclosure 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 apparatus.

[0099] Although the embodiments have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. EXAMPLES

[0100] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to these examples.

[0101] The values ​​in the examples were measured by the following methods.

[0102] (Perfluoroelastomer composition) 19 It was determined by F-NMR analysis.

[0103] (Iodine atom content of perfluoroelastomer) 20 ml of pure water was placed in a quartz flask, and 30 mg of a 1:1 (weight ratio) mixture of Na2CO3 and K2CO3 was added to 12 mg of perfluoroelastomer in a platinum basket. The mixture was burned in oxygen in the quartz flask, left for 30 minutes, and then 5 mg of Na2SO3 was added and shaken to dissolve the generated combustion gas in the liquid in the quartz flask. The concentration of iodine ions in the resulting solution was measured using a Shimadzu 20A ion chromatograph. The iodine content of the perfluoroelastomer was determined using a calibration curve created using a KI standard solution containing 0.5 ppm iodine ions and a KI standard solution containing 1.0 ppm iodine ions.

[0104] (Mooney Viscosity of Perfluoroelastomer) Measurements were performed using a Mooney viscometer MV2000E manufactured by ALPHA TECHNOLOGIES at 170°C or 100°C in accordance with JIS K6300.

[0105] (Triazine ring content in crosslinked product) The infrared spectrum of the crosslinked product was obtained using a Fourier transform infrared spectrophotometer (FT-IR), and the overtone vibration peak of the C–F bond (2360 cm -1 ) versus the triazine ring peak (1555 cm -1 The absorbance ratio (A1555 / A2360) of these two compounds was calculated, and the calculated absorbance ratio was regarded as the content of triazine rings in the crosslinked product.

[0106] (Iodine atom content in crosslinked product) The crosslinked product was subjected to an ashing treatment, and the ashed product was subjected to elemental analysis by ion chromatography.

[0107] (Silicon atom content in crosslinked product) The content of silicon atoms in the crosslinked product was calculated from the composition of the composition used to prepare the crosslinked product. The presence or absence and content of silicon atoms in the crosslinked product can also be measured by energy dispersive X-ray analysis (EDX) of the crosslinked product. In Table 1, the case where silicon atoms were detected in the crosslinked product by EDX is recorded as "present", and the case where silicon atoms were not detected in the crosslinked product by EDX is recorded as "absent".

[0108] (Total light transmittance, haze value) The measurement was carried out using a cross-linked product having a thickness of 2 mm in accordance with ASTM D1003, using Hazeguard II (product name) (manufactured by Toyo Seiki Seisakusho, Ltd.).

[0109] (Compression set rate) The compression set rate was measured according to the method described in ASTM D395 or JIS K6262. The O-rings produced in the examples and comparative examples were compressed to a compression rate of 25% at room temperature using a compression device (an O-ring with a thickness (wire diameter) of 3.5 mm was compressed to a thickness of 2.625 mm). Next, the compression device with the compressed O-ring fixed thereto was placed in an electric furnace and left at 300°C for 72 hours, after which the compression device was removed from the electric furnace. The O-ring was removed from the compression device and left in a constant temperature room at 23°C for 30 minutes, and the thickness (t2) of the O-ring was measured. The compression set was calculated using the following formula. Compression set rate (%) = (t0-t2) / (t0-t1) x 100 t0: original thickness of O-ring (mm) t1: Spacer thickness (mm) t2: Thickness of the O-ring after compression test (mm) In the above test, t0=3.5 mm and t1=2.625 mm.

[0110] (Normal physical properties) Using a crosslinked product having a thickness of 2 mm, the tensile strength at break (MPa), 100% modulus (MPa) and elongation at break (%) were measured in accordance with JIS-K6251.

[0111] (Hardness (ShoreA) Peak) Using a cross-linked product having a thickness of 2 mm, the hardness (Shore A) was measured (peak value) in accordance with JIS-K6253.

[0112] The following materials were used in the examples and comparative examples.

[0113] <Nitrile group-containing perfluoroelastomer (A)> Elastomer (a1) Composition: TFE / PMVE / CF2=CFOCF2CF(CF3)OCF2CF2CN=59.4 / 40.1 / 0.5 (mol%) Mooney Viscosity (ML1+20(170℃)):80 It has a polar end group (carboxylate group).

[0114] <Iodine- or bromine-containing perfluoroelastomer (B) not containing nitrile groups> Elastomer (b1) Composition: TFE / PMVE / CF2=CFOCF2CF2CH2I=66.7 / 33.2 / 0.1 (mol%) Mooney Viscosity (ML1+10(100℃)): 65 Iodine atom content: 0.40wt% Elastomer (b2) Composition: TFE / CF2=CF(OCF2CF(CF3)2OCF2CF2CF3 / CF2=CFOCF2CF2CH2I=79.6 / 20.0 / 0.4 (mol%) Mooney Viscosity (ML1+10(100℃)):27 Iodine atom content: 0.20wt% Elastomer (b3) Composition: TFE / PMVE=62 / 38 (mol%) Mooney Viscosity (ML1+10(100℃)):50 Iodine atom content: 0.24wt%

[0115] <Compound (C)> Compound (c1): Silicon nitride (Si3N4) Compound (c2): Biuret Compound (c3): Urea

[0116] Comparative Example 1 0.25 phr of silicon nitride (Si3N4) (SN-A00 manufactured by Ube Industries, Ltd.) was added to the elastomer (a1) and kneaded with an open roll to prepare a crosslinkable fluororubber composition. The obtained fluororubber composition was pressed at 180°C for 20 minutes to crosslink, and then subjected to oven crosslinking at 200 to 290°C for 18 hours in an oven to produce a molded product of a crosslinked product having a thickness of 2 mm and a molded product of an O-ring (AS-568A-214 size). The obtained molded product was used to measure the total light transmittance, haze value, compression set rate, and normal physical properties according to the method described above. The results are shown in Table 1.

[0117] Comparative Example 2 A fluororubber composition and a molded article were prepared in the same manner as in Comparative Example 1, except that biuret (manufactured by Kanto Chemical Co., Ltd.) was used instead of silicon nitride, and various evaluations were carried out.

[0118] Comparative Example 3 A fluororubber composition and a molded article were prepared in the same manner as in Comparative Example 1, except that urea (manufactured by Kanto Chemical Co., Ltd.) was used instead of silicon nitride, and various evaluations were carried out.

[0119] Examples 1 to 4 According to the compounding composition shown in Table 1, silicon nitride (SN-A00 manufactured by Ube Industries, Ltd.) and elastomer (b1) were added to elastomer (a1) and kneaded with an open roll to prepare a crosslinkable fluororubber composition. The obtained fluororubber composition was pressed at 180°C for 20 minutes to crosslink, and then further subjected to oven crosslinking at 200 to 290°C for 18 hours in an oven to produce a molded product of a crosslinked product having a thickness of 2 mm and a molded product of an O-ring (AS-568A-214 size). The obtained molded product was used to measure the total light transmittance, haze value, compression set rate, and normal physical properties according to the methods shown above.

[0120] Example 5 A fluororubber composition and a molded article were prepared in the same manner as in Example 3, except that the elastomer (b2) was used instead of the elastomer (b1), and various evaluations were carried out.

[0121] Example 6 A fluororubber composition and a molded article were prepared in the same manner as in Example 3, except that the elastomer (b3) was used instead of the elastomer (b1), and various evaluations were carried out.

[0122] The above results are shown in Table 1.

[0123] [Table 1]

Claims

1. A nitrile group-containing perfluoroelastomer (A), an iodine- or bromine-containing perfluoroelastomer (B) that does not contain nitrile groups, and A perfluoroelastomer composition containing silicon nitride (C) is crosslinked, A perfluoroelastomer crosslinked product having a haze value of 95% or less and a compression set of 25 to 40%, The compression set is a compression set measured by leaving the material at 300° C. for 72 hours at a compression rate of 25%. The perfluoroelastomer crosslinked product has an iodine atom and bromine atom content of 0.0001% by mass or more and 0.010% by mass or less.

2. The perfluoroelastomer crosslinked product according to claim 1, which has a total light transmittance of 85% or more.

3. The perfluoroelastomer crosslinked product according to claim 1 or 2, which contains a triazine ring.

4. 3. The perfluoroelastomer crosslinked product according to claim 1, which contains silicon atoms.

Images