Peroxide-crosslinked fluororubber composition, method for producing same, and rubber molded article

Abstract

This peroxide-crosslinked fluororubber composition is characterized by containing (a) a perfluoropolyether-based fluororubber mixture and (b) an organopolysiloxane and having a volume ratio (a):(b) of the component (a) to the component (b) of 95:5 to 99:1, and gives a cured product which is excellent in terms of heat resistance, chemical resistance, solvent resistance, low-temperature characteristics, and the like, and has excellent roll processability.

Description

Peroxide-crosslinkable fluororubber composition, its manufacturing method, and rubber molded product

[0001] The present invention relates to a peroxide-crosslinkable fluororubber composition that gives a cured product excellent in heat resistance, chemical resistance, solvent resistance, low-temperature properties, etc., and also has excellent roll processability; a method for producing the composition; and a rubber molded article obtained by curing the composition.

[0002] Patent Document 1 (JP 2003-201401 A) discloses a perfluoropolyether-based fluororubber composition that is excellent in heat resistance, chemical resistance, solvent resistance, low-temperature properties, etc. However, its roll processability is insufficient.

[0003] Therefore, in order to improve the roll processability, Patent Document 2 (JP 2006-161032 A) proposes mixing silicone rubber with such a perfluoropolyether-based fluororubber composition. However, although the perfluoropolyether-based fluororubber composition described in Patent Document 2 improves the roll processability, it also reduces solvent resistance, leaving room for improvement.

[0004] JP 2003-201401 A JP 2006-161032 A

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a peroxide-crosslinkable fluororubber composition which gives a cured product excellent in heat resistance, chemical resistance, solvent resistance, low-temperature properties, etc. and which also has excellent roll processability, a method for producing the composition, and a rubber molded article obtained by curing the composition.

[0006] As a result of extensive research into achieving the above object, the present inventors have found that a peroxide-crosslinkable fluororubber composition containing (a) a perfluoropolyether-based fluororubber mixture and (b) an organopolysiloxane, wherein the volume ratio of components (a) to (b) is (a):(b) = 95:5 to 99:1, gives a cured product that is excellent in heat resistance, chemical resistance, solvent resistance, low-temperature properties, etc., and also has excellent roll processability, which has led to the present invention.

[0007] Accordingly, the present invention provides the following peroxide-crosslinkable fluororubber composition, its production method, and rubber molded article. [1] A peroxide-crosslinkable fluororubber composition comprising (a) a perfluoropolyether-based fluororubber mixture, and (b) an organopolysiloxane, wherein the volume ratio of components (a):(b) is (a):(b)=95:5 to 99:1. [2] The peroxide-crosslinkable fluororubber composition according to [1], wherein the (a) perfluoropolyether-based fluororubber mixture comprises: (A) an addition reaction product of a perfluoro compound (I) having at least two alkenyl groups in the molecule and having a perfluoroalkylene group or a divalent perfluoropolyether group in the main chain, and an organosilicon compound (II) having at least two SiH groups in the molecule, and (B) a reinforcing filler. [3] The (b) organopolysiloxane is a peroxide-crosslinkable fluororubber composition represented by the following average composition formula (1) (R 11 ) x SiO (4-x) / 2 (1) (wherein, R 11 [4] The peroxide-crosslinkable fluororubber composition according to [1] or [2], wherein component (I) is an organopolysiloxane represented by the following general formula (2): Rf[-U-Z(-Y-X) β ]2 (2) (wherein Rf is a perfluoroalkylene group or a divalent perfluoropolyether group; U is independently a single bond, a carbonyl bond, or a divalent organic group; Z is independently a single bond, a nitrogen atom, a silicon atom, a carbon atom, a phosphorus atom, or a trivalent to octavalent organic group; Y is independently a single bond or a divalent organic group; X is independently an alkenyl group; and β is an integer of 1 to 7, provided that U and Z are not simultaneously single bonds). [5] The peroxide-crosslinkable fluororubber composition according to [2] or [3], wherein Rf in formula (2) is -C a F 2aThe peroxide-crosslinkable fluororubber composition according to [4], which contains one or more repeating units (perfluorooxyalkylene units) represented by the following general formula (3): (In the formula, R 4 are independently unsubstituted or substituted monovalent hydrocarbon groups containing no aliphatic unsaturated bonds; and W is a divalent organic group. [7] The peroxide-crosslinkable fluororubber composition according to any one of [2] to [5], wherein W in formula (3) is an organosilicon compound represented by any one of formulas (i) to (iii): [wherein Rf″ is a perfluoroalkylene group or a divalent perfluoropolyether group, R 5 are independently an oxygen atom or an unsubstituted or substituted divalent hydrocarbon group, R 6 are independently unsubstituted or substituted monovalent hydrocarbon groups, R 7 is an unsubstituted or substituted monovalent hydrocarbon group or a dimethylsiloxy group, and D is independently —CH—, —CHO—, —CHOCH—, or —E-NR 8 SO2- or -E-NR 8 -CO- (wherein E is -CH2- or the following formula (wherein Me is a methyl group), and R 8is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group.), Rf' is a monovalent perfluoropolyether group or perfluoroalkyl group, and z is independently 0 or 1.] [8] The peroxide-crosslinkable fluororubber composition according to any of [2] to [7], wherein the (B) reinforcing filler is a silica-based reinforcing filler, quartz powder, fused quartz powder, diatomaceous earth, or calcium carbonate. [9] A rubber molded article obtained by curing the peroxide-crosslinkable fluororubber composition according to any of [1] to [8].

[10] A method for producing the peroxide-crosslinkable fluororubber composition according to any of [1] to [8], comprising kneading component (a) and component (b) in an internal kneader.

[11] The method for producing a peroxide-crosslinkable fluororubber composition according to

[10] , wherein the internal kneader is a pressure kneader or a Banbury mixer.

[0008] According to the peroxide-crosslinkable fluororubber composition of the present invention, it is possible to provide a peroxide-crosslinkable fluororubber composition which is excellent in heat resistance, chemical resistance, solvent resistance, low-temperature properties, etc., and also has excellent roll processability.

[0009] In the present invention, the "roll processability" refers to the ease of processing (workability) when a fluororubber composition is subjected to roll processing such as kneading using processing rolls such as two rolls, and the degree of adhesion of the fluororubber composition to the processing rolls during roll processing serves as a guide.

[0010] The present invention is described in detail below. The peroxide-crosslinkable fluororubber composition of the present invention is characterized by containing (a) a perfluoropolyether-based fluororubber mixture, and (b) an organopolysiloxane, and the volume ratio of components (a) and (b) is (a):(b) = 95:5 to 99:1.

[0011] [Component (a): Perfluoropolyether-based fluororubber mixture] The perfluoropolyether-based fluororubber mixture of component (a) comprises: (A) an addition reaction product of a perfluoro compound (I) having at least two alkenyl groups in the molecule and having a perfluoroalkylene group or a divalent perfluoropolyether group in the main chain, with an organosilicon compound (II) having at least two SiH groups in the molecule; and (B) a reinforcing filler.

[0012] [Component (A)] Component (A) is an addition reaction product of a perfluoro compound (I) having at least two alkenyl groups in the molecule and having a perfluoroalkylene group or a divalent perfluoropolyether group in the main chain, and an organosilicon compound (II) having at least two SiH groups in the molecule.The addition reaction product of component (A) is preferably a high molecular weight polymer, and is a non-liquid (raw rubber-like) perfluoropolyether fluororubber that does not have self-flowability (high viscosity) at room temperature (25°C±15°C).

[0013] <(I): Perfluoro Compound Having at Least Two Alkenyl Groups in the Molecule and a Perfluoroalkylene Group or a Divalent Perfluoropolyether Group in the Main Chain> Component (I) is a perfluoro compound having at least two alkenyl groups in the molecule and a perfluoroalkylene group or a divalent perfluoropolyether group in the main chain. The perfluoro compound of component (I) is a compound that is technically difficult to synthesize into a high molecular weight polymer such as a resin or rubber by itself, and has at least two (e.g., 2 to 14), preferably 2 to 6, and particularly preferably 2, alkenyl groups in the molecule and a perfluoroalkylene group or a divalent perfluoropolyether group in the main chain, and preferably has a kinematic viscosity at 25°C of 25 to 1,000,000 mm 2 It is a linear perfluoro compound having the formula:

[0014] Such component (I) is preferably a perfluoro compound represented by the following general formula (2): Rf[-U-Z(-Y-X) β]2 (2) (In the formula, Rf is a perfluoroalkylene group or a divalent perfluoropolyether group; U is independently a single bond, a carbonyl bond, or a divalent organic group; Z is independently a single bond, a nitrogen atom, a silicon atom, a carbon atom, a phosphorus atom, or a trivalent to octavalent organic group; Y is independently a single bond or a divalent organic group; X is independently an alkenyl group; and β is an integer of 1 to 7, provided that U and Z are not simultaneously single bonds.)

[0015] In the above formula (2), Rf is a perfluoroalkylene group or a divalent perfluoropolyether group, and is preferably a divalent perfluoropolyether group.

[0016] The perfluoroalkylene group includes C n F 2n (n is an integer of 1 to 6, preferably an integer of 2 to 4), and the following can be exemplified: -CF2- -CF2CF2- -CF2CF2CF2- -CF2CF2CF2CF2- -CF2CF2CF2CF2CF2CF2- -CF2CF2CF2CF2CF2CF2-

[0017] The divalent perfluoropolyether group may be a group represented by the following formula -C a F 2a O- (wherein a is an integer of 1 to 6), and examples thereof include those represented by the following general formula (4): -(C a F 2a O) b - (4) (wherein a is an integer of 1 to 6, and b is an integer of 1 to 300, preferably an integer of 1 to 200.)

[0018] Above-C a F 2aExamples of the repeating unit represented by O- include units represented by the following formulas: -CF2O- -CF2CF2O- -CF2CF2CF2O- -CF(CF3)CF2O- -CF(CF3)OCF2- -CF2OCF(CF3)- -CF2CF2CF2CF2CF2O- -CF2CF2CF2CF2CF2CF2O- -CF2CF2CF2CF2CF2CF2CF2O- -C(CF3)2O-

[0019] Among these, the repeating units represented by the following formulae are particularly preferred: -CF2O- -CF2CF2O- -CF2CF2CF2O- -CF(CF3)CF2O- -CF(CF3)OCF2- -CF2OCF(CF3)-

[0020] The divalent perfluoropolyether group may be composed of one of the above repeating units or a combination of two or more of them.

[0021] As Rf, for example, a group represented by the following formula is preferable. (In the formula, p', q', r', s', r2', and r3' each represent an integer of 1 or more, and the sum of p', q', r', s', r2', and r3' is 2 to 300. e is an integer of 0 to 6. In addition, the repeating units shown in parentheses with p', q', r', and s' may be bonded randomly.)

[0022] In the above formula (2), U is independently a single bond, a carbonyl bond, or a divalent organic group. The divalent organic group is preferably an unsubstituted or substituted divalent hydrocarbon group having 2 to 12 carbon atoms, such as an alkylene group such as an ethylene group, a propylene group (a trimethylene group, a methylethylene group), a butylene group (a tetramethylene group, a methylpropylene group), a hexamethylene group, or an octamethylene group, an arylene group such as a phenylene group, or a combination of two or more of these groups (e.g., an alkylene-arylene group). The divalent hydrocarbon group having 2 to 12 carbon atoms includes an amide bond, an ether bond, a carbonyl bond, an ester bond, a diorganosilylene group such as a dimethylsilylene group, and —Si[OH][(CH2) fSi(CH3)3]- (f is an integer of 2 to 4), or may be a group in which some or all of the hydrogen atoms bonded to carbon atoms have been substituted with halogen atoms such as fluorine or iodine. The number of carbon atoms in a divalent hydrocarbon group having 2 to 12 carbon atoms that is preferred as a divalent organic group is the number of carbon atoms in the unsubstituted divalent hydrocarbon group; for example, when the divalent hydrocarbon group contains the above structure such as a dimethylsilylene group, the number of carbon atoms in the above structure is not counted.

[0023] Examples of U include groups represented by the following structures: In the following structures, it is preferred that the left bond is bonded to Rf and the right bond is bonded to Z: —(CH) u —O—(CH2) v - -CF2- -OCF2- -OCF(CF3)- (In the formula, f is an integer of 2 to 4, h is an integer of 2 to 6, preferably an integer of 2 to 4, u and v each independently is an integer of 1 to 4, g is an integer of 2 to 4, and Me is a methyl group.)

[0024] In the above formula (2), Z is independently a single bond, a nitrogen atom, a silicon atom, a carbon atom, a phosphorus atom, or a trivalent to octavalent organic group, and the trivalent to octavalent (the above (β+1) valent) organic group may contain at least one of a nitrogen atom, an oxygen atom, a silicon atom, a carbon atom, and a phosphorus atom. Specific examples of Z include a single bond, a trivalent group represented by -N=, a trivalent group represented by -P=, a trivalent group represented by -PO=, a -R 1 a trivalent group represented by C=, -R 3 Examples include a group selected from a trivalent group represented by Si=, a tetravalent group represented by -C≡, a tetravalent group represented by -O-C≡, and a tetravalent group represented by -Si≡, or a trivalent to octavalent siloxane residue. Note that U and Z cannot simultaneously be single bonds.

[0025] In the above, R 1are each independently preferably a group having a repeating unit of an alkyl group having 1 to 3 carbon atoms, a hydroxyl group, or an oxyalkylene group having 1 to 3 carbon atoms which may be interrupted by a diorganosiloxane structure having 2 to 51 silicon atoms, or R 2 3SiO- is a silyl ether group, and R 2 are each independently a hydrogen atom, an alkyl group preferably having 1 to 3 carbon atoms, an aryl group such as a phenyl group, or an alkoxy group having 1 to 3 carbon atoms. 3 are each independently preferably an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 or 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a hydroxyl group, or a chloro group. When Z is a siloxane residue, it preferably has a linear, branched, or cyclic organopolysiloxane structure having 2 to 51 silicon atoms, preferably 2 to 13 silicon atoms, more preferably 2 to 11 silicon atoms, and even more preferably 2 to 5 silicon atoms. The organopolysiloxane preferably has an unsubstituted or fluorine-substituted alkyl group or phenyl group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, such as methyl, ethyl, propyl, butyl, or C3F7-C3H6-. In addition, a silalkylene structure in which two silicon atoms are bonded by an alkylene group, i.e., Si-(CH2) h In the above formula, h is an integer of 2 to 6, preferably an integer of 2 to 4.

[0026] Examples of such Z include the following: In the following structure, it is preferred that the bond on the left side is bonded to U, and the other bond is bonded to Y. (In the formula, i is an integer of 1 to 20, k is an integer of 1 to 50, and Me is a methyl group.)

[0027] In the above formula (2), Y is independently a single bond or a divalent organic group, and the divalent organic group is preferably a linking group consisting of one or more structures selected from the group consisting of -C(=O)-NR'- (R' is a hydrogen atom, a methyl group, or a phenyl group), an ether bond, a carbonyl bond, an ester bond, and a diorganosilylene group such as a dimethylsilylene group, which may contain an unsubstituted or substituted divalent hydrocarbon group having 2 to 12 carbon atoms. Examples of the unsubstituted or substituted divalent hydrocarbon group having 2 to 12 carbon atoms include alkylene groups such as ethylene, propylene (trimethylene, methylethylene), butylene (tetramethylene, methylpropylene), hexamethylene, and octamethylene, arylene groups such as phenylene, and combinations of two or more of these groups (e.g., alkylene-arylene groups). When Z is a single bond, Y is preferably a single bond.

[0028] Examples of Y include groups represented by the following structures: In the following structures, it is preferred that the left bond is bonded to Z and the right bond is bonded to X. (In the formula, f is an integer of 2 to 4, u is an integer of 1 to 4, g is an integer of 2 to 4, and Me is a methyl group.)

[0029] In the above formula (2), X is independently an alkenyl group, preferably having 2 to 8 carbon atoms, particularly 2 to 6 carbon atoms, and having a CH═CH— structure. Examples include a vinyl group, an allyl group, a propenyl group, an isopropenyl group, a butenyl group, and a hexenyl group, and among these, a vinyl group and an allyl group are particularly preferred.

[0030] In the above formula (2), β is an integer of 1 to 7, preferably an integer of 1 to 3, and more preferably 1.

[0031] Examples of the perfluoro compound represented by the above formula (2) include the following.

[0032] (In the formula, p1, q1, r1, and s1 each independently represent an integer of 1 to 200, and the total of p1, q1, r1, and s1 is 3 to 300, and the repeating units shown in parentheses may be bonded randomly. Me is a methyl group.)

[0033] (In the formula, c1 and d1 each represent an integer of 1 to 150, and the sum of c1 and d1 is 2 to 300, and the repeating units shown in parentheses may be bonded randomly. Me represents a methyl group, and Et represents an ethyl group.)

[0034] (In the formula, c2 and d2 each represent an integer of 1 to 150, and the sum of c2 and d2 is 2 to 300, and the repeating units shown in parentheses may be bonded randomly. Me represents a methyl group.)

[0035] The perfluoro compound (I) has a kinematic viscosity at 25°C of 25 to 1,000,000 mm 2 / s, and 100 to 100,000 mm 2 It is more preferable that the kinematic viscosity is 25 mm / s. 2 If the viscosity is less than 1,000,000 mm / s, the component (A) may not be obtained as a crude rubber. 2 If the kinematic viscosity exceeds 1 / s, the handling properties during preparation of component (A) may be significantly impaired. The kinematic viscosity is a value measured using a Cannon-Fenske viscometer according to the method described in JIS Z8803:2011.

[0036] The component (I) may be used alone or in combination of two or more types.

[0037] <(II): Organosilicon Compound Having at Least Two SiH Groups in the Molecule> The component (II) is an organosilicon compound having at least two SiH groups in the molecule, and is preferably an organosilicon compound represented by the following general formula (3): (In the formula, R 4 are independently unsubstituted or substituted monovalent hydrocarbon groups containing no aliphatic unsaturated bonds; and W is a divalent organic group.

[0038] In the above formula (3), R 4 are independently unsubstituted or substituted monovalent hydrocarbon groups that do not contain aliphatic unsaturated bonds, preferably having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms. Specific examples include alkyl groups such as methyl, ethyl, propyl, and butyl; aryl groups such as phenyl and tolyl; aralkyl groups such as benzyl; and trifluoropropyl groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms or the like. Of these, methyl is preferred.

[0039] In the above formula (3), W is a divalent organic group, and is preferably any of the groups represented by the following formulae (i) to (iii). [wherein Rf″ is a perfluoroalkylene group or a divalent perfluoropolyether group, R 5 are independently an oxygen atom or an unsubstituted or substituted divalent hydrocarbon group, R 6 are independently unsubstituted or substituted monovalent hydrocarbon groups, R 7 is an unsubstituted or substituted monovalent hydrocarbon group or a dimethylsiloxy group, and D is independently —CH—, —CHO—, —CHOCH—, or —E-NR 8 SO2- or -E-NR 8 -CO- (wherein E is -CH2- or the following formula (wherein Me is a methyl group), and R 8 is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, Rf′ is a monovalent perfluoropolyether group or perfluoroalkyl group, and z is independently 0 or 1.

[0040] In the above formula (i), R5 are independently an oxygen atom or an unsubstituted or substituted divalent hydrocarbon group, and the unsubstituted or substituted divalent hydrocarbon group is preferably one having 1 to 8 carbon atoms, and examples thereof include alkylene groups such as methylene, ethylene, propylene (trimethylene, methylethylene), butylene (tetramethylene, methylpropylene), hexamethylene, and octamethylene; cycloalkylene groups such as cyclopropylene, cyclobutylene, cyclopentylene, cyclohexylene, cyclooctylene, cyclononylene, and cyclodecylene; arylene groups such as phenylene; combinations of two or more of these groups (e.g., alkylene-arylene groups); and groups in which some of the hydrogen atoms of these groups have been substituted with halogen atoms or the like. 5 is preferably an oxygen atom or a methylene group.

[0041] In the above formula (i), R 6 are independently an unsubstituted or substituted monovalent hydrocarbon group, preferably having 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms. Specific examples include alkyl groups such as methyl, ethyl, propyl, and butyl; alkenyl groups such as vinyl and allyl; aryl groups such as phenyl and tolyl; aralkyl groups such as benzyl; and groups in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms or the like, such as trifluoropropyl, C3F7C2H4-, C4F9C2H4-, CH2=CHC3F6C2H4-, or CH2=CHC4F8C2H4-, of which preferred are methyl, C4F9C2H4-, and CH2=CHC4F8C2H4-.

[0042] In the above formula (ii), Rf" is a perfluoroalkylene group or a divalent perfluoropolyether group, and examples thereof include those similar to Rf in the above formula (2). Rf" is preferably a perfluoroalkylene group, and particularly preferably a -CFCFCFCFCF- group.

[0043] In the above formulas (ii) and (iii), R 7 is an unsubstituted or substituted monovalent hydrocarbon group or a dimethylsiloxy group, and the unsubstituted or substituted monovalent hydrocarbon group is the same as R6 Examples of the unsubstituted or substituted monovalent hydrocarbon groups are the same as those of R 7 is preferably a methyl group, a C4F9C2H4- group or a CH2=CHC4F8C2H4- group.

[0044] In the above formulas (ii) and (iii), D independently represents -CH2-, -CH2O-, -CH2OCH2-, or -E-NR 8 SO2- or -E-NR 8 -CO- (wherein E is -CH2- or the following formula (wherein Me is a methyl group), and R 8 is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group.

[0045] Here, R 8 is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group, and the unsubstituted or substituted monovalent hydrocarbon group is the same as R 6 Examples of the unsubstituted or substituted monovalent hydrocarbon groups are the same as those of R 8 As the alkyl group, a methyl group, an ethyl group, a trifluoromethyl group, a trifluoroethyl group, a pentafluoroethyl group, a phenyl group, and a pentafluorophenyl group are preferred.

[0046] In the above formulas (ii) and (iii), z is independently 0 or 1, and is preferably 0.

[0047] In the above formula (iii), Rf' is a monovalent perfluoropolyether group or a perfluoroalkyl group, and is preferably a perfluoroalkyl group.

[0048] As the monovalent perfluoropolyether group, for example, a group represented by the following formula is preferred. (In the formula, p', q', r', and s' each represent an integer of 1 or more, and the total of p', q', r', and s' is 2 to 300. In addition, each repeating unit shown in parentheses with p', q', r', and s' may be bonded randomly.)

[0049] The perfluoroalkyl group may be C n F 2n+1(n is an integer of 1 to 6, preferably an integer of 2 to 4), and the following can be exemplified: CF3- CF3CF2- CF3CF2CF2- CF3CF2CF2CF2- CF3CF2CF2CF2CF2- CF3CF2CF2CF2CF2CF2-

[0050] Specific examples of organosilicon compounds represented by formula (3) in which W is formula (i) include the compounds shown below. (In the formula, Me is a methyl group.)

[0051] Specific examples of organosilicon compounds represented by formula (3) in which W is formula (ii) include the compounds shown below. (In the formula, Me is a methyl group.)

[0052] Specific examples of organosilicon compounds represented by formula (3) in which W is formula (iii) include the compounds shown below. (In the formula, Me is a methyl group.)

[0053] The component (II) may be used alone or in combination of two or more. It is preferable to use a component (II) having an alkenyl group in the molecule, and it is more preferable to use a combination of a component (II) having an alkenyl group in the molecule and a component (II) not having an alkenyl group in the molecule. When a component (II) having an alkenyl group in the molecule and a component (II) not having an alkenyl group in the molecule are used in combination, the amounts used are preferably such that the molar ratio of the component (II) having an alkenyl group to the component (II) not having an alkenyl group is 99:1 to 1:99, particularly 80:20 to 20:80.

[0054] <(A): Preparation of Addition Reaction Product> The addition reaction product of component (A) is obtained by an addition reaction (hydrosilylation reaction) between the alkenyl groups in component (I) and the SiH groups in component (II). Specifically, the addition reaction product of component (A) can be prepared by adding a hydrosilylation reaction catalyst to a mixture of components (I) and (II) and causing the hydrosilylation reaction.

[0055] The reaction ratio of component (I) and component (II) is preferably such that the number of SiH groups in component (II) is 1.00 to 2.00 mol per 1 mol of alkenyl groups in component (I), and more preferably 1.01 to 1.50 mol. If the reaction ratio is less than 1.00 mol, the resulting component (A) may not be in the form of a crude rubber, while if the reaction ratio exceeds 2.00 mol, the heat resistance of the resulting cured composition may decrease.

[0056] Hydrosilylation reaction catalysts are generally noble metals (particularly platinum group metals) or compounds thereof, and because they are expensive, platinum or platinum compounds are often used because they are relatively easy to obtain.

[0057] Examples of platinum compounds include chloroplatinic acid, complexes of chloroplatinic acid with olefins such as ethylene, complexes of chloroplatinic acid with alcohols or vinylsiloxanes, and metallic platinum supported on silica, alumina, carbon, etc. Hydrosilylation reaction catalysts other than platinum or platinum compounds also include rhodium, ruthenium, iridium, and palladium compounds, such as RhCl(PPh), RhCl(CO)(PPh), and Ru(CO). 12 , IrCl(CO)(PPh3)2, Pd(PPh3)4, etc. In the above formula, Ph is a phenyl group.

[0058] When using these catalysts, if they are solid catalysts, they can be used in a solid state. However, in order to obtain a more uniform cured product, it is preferable to use chloroplatinic acid or a complex dissolved in a suitable solvent such as toluene or ethanol.

[0059] These hydrosilylation reaction catalysts may be used alone or in combination of two or more. The amount of these catalysts used is not particularly limited, and the desired curing rate can be obtained with any catalytic amount, but from an economical standpoint or to obtain a good cured product, the amount is usually 0.1 to 2,000 ppm, preferably 0.1 to 500 ppm, and particularly preferably 0.5 to 200 ppm (calculated as the mass of platinum group metal atoms) relative to the total mass of components (I) and (II), and this amount can be increased or decreased as appropriate depending on the desired curing rate.

[0060] The conditions for the addition reaction (hydrosilylation reaction) can be appropriately selected, and the reaction may be carried out at room temperature, but to accelerate the reaction, it can be carried out by heating at 50 to 200° C. The reaction time can be 10 minutes to 12 hours, and particularly 1 to 2 hours.

[0061] The addition reaction product of component (A) obtained by the above method preferably has alkenyl groups derived from component (II) in the molecule. The amount of these alkenyl groups is preferably 5.0×10 -5 ~1.2 × 10 -2 mol / 100g, and preferably 1.0 x 10 -4 ~1.0 x 10 -2 If the amount of alkenyl groups is too small, the heat resistance of the cured product of the composition obtained may decrease, whereas if the amount of alkenyl groups is too large, the roll processability of the composition obtained may be significantly deteriorated. 1 It can be measured by H-NMR, FT-IR, etc.

[0062] The addition reaction product of component (A) obtained by the above method has a kinematic viscosity of 1 to 100 mm when dissolved in 10% by mass HFE-7200 (Novec (registered trademark), manufactured by 3M Co.) at 25°C. 2 / s, and 5 to 50 mm 2 / s is more preferable. If the solution kinematic viscosity is too low, the roll processability of the resulting composition may be significantly impaired, whereas if it is too high, the dispersibility of component (B) in component (A) may be poor. The solution kinematic viscosity can be measured using a Cannon-Fenske viscometer according to the method described in JIS Z8803:2011. Because the addition reaction product of component (A) has a gummy appearance, viscosity measurement using a rotational viscometer or the like may be difficult, and measurement using solution kinematic viscosity is therefore preferred.

[0063] [Component (B)] Component (B) is a reinforcing filler. Examples of reinforcing fillers include silica-based reinforcing fillers, quartz powder, fused quartz powder, diatomaceous earth, calcium carbonate, and other reinforcing or semi-reinforcing fillers. Examples of silica-based reinforcing fillers include silica powders such as fumed silica (fumed silica or dry silica), precipitated silica (wet silica), spherical silica (fused silica), sol-gel silica, and silica aerogel, as well as silica powders (surface-treated silica powders) obtained by treating the surface of the silica powder with various organochlorosilanes, organodisilazanes, cyclic organopolysilazanes, and the like. Furthermore, the silica-based reinforcing filler may be a silica powder obtained by re-treating the surface-treated silica powder with an organosilane or organosiloxane having a monovalent perfluoroalkyl group or a monovalent perfluorooxyalkyl group. Of these, fumed silica is particularly preferred as component (B) from the viewpoints of improving the mechanical strength of the resulting cured product and improving the dispersion stability of each component, and fumed silica treated with a silicon compound-based surface treatment agent such as silane is preferred from the viewpoint of improving dispersibility.

[0064] Examples of silicon compound surface treatment agents include organochlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane, vinyldimethylchlorosilane, divinylmethylchlorosilane, and trivinylchlorosilane; silane compounds having a hydrolyzable group such as organoalkoxysilanes such as dimethyldimethoxysilane, trimethylmethoxysilane, methyltrimethoxysilane, vinyldimethylmethoxysilane, divinylmethylmethoxysilane, trivinylmethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, methyltriethoxysilane, vinyldimethylethoxysilane, divinylmethylethoxysilane, and trivinylethoxysilane; and hexamethyldisilane. and organodisilazanes such as 1,3-divinyl-1,1,3,3-tetramethyldisilazane, 1,3-diphenyl-1,1,3,3-tetramethyldisilazane, heptamethyldisilazane, and 1,3-bis(chloromethyl)-1,1,3,3-tetramethyldisilazane; and cyclic organopolysilazanes such as 1,3,5-trimethyl-1,3,5-trivinylcyclotrisilazane and 1,1,3,3,5,5-hexamethylcyclotrisilazane. Of these, silicon compounds having a hydrolyzable group, such as dimethyldichlorosilane and organochlorosilanes such as trimethylchlorosilane, silazane compounds such as hexamethyldisilazane, and cyclic silazanes such as hexamethylcyclotrisilazane are particularly preferred.

[0065] In this hydrophobic treatment, the silica powder whose surface has been treated with a surface treatment agent is preferably one that has been treated directly in the powder state in advance, and the usual treatment method can be a well-known technique, for example, by placing the untreated silica powder and the treatment agent in a mechanical kneading device sealed at atmospheric pressure or in a fluidized bed, mixing them at room temperature or by heat treatment in the presence of an inert gas as needed, optionally using a catalyst and water to promote hydrolysis, and then drying to prepare the resulting mixture. The amount of the surface treatment agent to be added should be equal to or greater than the amount calculated from the area that the surface treatment agent can cover on the surface of the silica powder.

[0066] The specific surface area of ​​the silica powder measured by the BET method is 50 m 2 / g or more, and further, since the viscosity increases significantly when the silica powder is blended into the composition, making blending difficult, it is preferable that the silica powder content is 300 m / g or more. 2 / g or less is preferable.

[0067] The component (B) may be used alone or in combination of two or more types.

[0068] In the present invention, the reinforcing filler of component (B) preferably has a bulk density of 30 to 180 g / L, particularly 40 to 150 g / L. If the bulk density of the hydrophobic silica powder is less than 30 g / L, the viscosity of the resulting composition increases, making it difficult to blend, while if it exceeds 180 g / L, a sufficient reinforcing effect may not be achieved. In the present invention, the bulk density is a value measured by a tapping method or the like.

[0069] Furthermore, when this reinforcing filler is subjected to a hydrophobic treatment, the degree of hydrophobic treatment is preferably in the range of 0.1 to 20 mass% and more preferably 0.5 to 10 mass% in terms of the amount of surface carbon (carbon content: mass%) in the entire hydrophobic silica powder after treatment. If the surface carbon amount is less than 0.1 mass%, uniform kneading with component (A) may be difficult, while if the surface carbon amount exceeds 20 mass%, the resulting composition may not have sufficient mechanical strength in its cured form. In the present invention, the surface carbon amount is a value measured by a known elemental analysis method.

[0070] In addition, when the reinforcing filler of component (B) has alkenyl groups in the surface carbon after treatment, the amount of the surface alkenyl groups is 1.0 × 10 -3 ~2.0 x 10 -2 mol / 100g, and preferably in the range of 1.5×10 -3 ~1.5 x 10 -2 It is more preferable that the amount of surface alkenyl groups is in the range of 2.0×10 -2 If the amount exceeds 100 mol / 100 g, it may be difficult to uniformly knead the component (A). In the present invention, the amount of surface alkenyl groups is a value measured by FT-IR.

[0071] The amount of this reinforcing filler added is preferably 10 to 60 parts by mass, and more preferably 15 to 50 parts by mass, per 100 parts by mass of component (A). If the amount is less than 10 parts by mass, the resulting cured product may have insufficient mechanical strength, while if the amount is more than 60 parts by mass, the cured product may become brittle and have reduced mechanical strength.

[0072] (a) The perfluoropolyether-based fluororubber mixture can be obtained by mixing the above-mentioned components (A) and (B) in predetermined amounts in accordance with a conventional method.

[0073] [Component (b): Organopolysiloxane] The organopolysiloxane of component (b) acts as a roll processability improver in the peroxide-crosslinked fluororubber composition of the present invention, and is preferably represented by the following average composition formula (1): (R 11 ) x SiO (4-x) / 2 (1) (wherein, R 11 represents an unsubstituted or substituted monovalent hydrocarbon group, and x is a number satisfying the relationship 1.85<x<2.10.

[0074] In the above formula (1), R 11 is an unsubstituted or substituted monovalent hydrocarbon group, preferably having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and specific examples include alkyl groups such as methyl, ethyl, propyl, and butyl, alkenyl groups such as vinyl and allyl, aryl groups such as phenyl and tolyl, aralkyl groups such as benzyl, and trifluoropropyl groups in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms or the like, with methyl and vinyl being preferred among these. Furthermore, the organopolysiloxane of component (b) may have hydroxyl groups bonded to silicon atoms at the molecular chain terminals.

[0075] In the above formula (1), x is a number that satisfies 1.85<x<2.10.

[0076] In the present invention, the degree of polymerization of the organopolysiloxane of component (b) is not particularly limited, but is, for example, from 2 to 10,000. In the present invention, the degree of polymerization (or molecular weight) can be determined, for example, as the polystyrene-equivalent number average degree of polymerization (or number average molecular weight) in gel permeation chromatography (GPC) analysis using toluene, tetrahydrofuran (THF), or the like as a developing solvent.

[0077] The viscosity of the organopolysiloxane of component (b) is not particularly limited, but it is preferable that the viscosity of a 30% by weight toluene solution (viscosity of a solution in which 30% by weight of the organopolysiloxane is dissolved in toluene) at 25° C. is 1 to 100,000 mPa s. In the present invention, the viscosity is a value measured using a rotational viscometer according to the method described in JIS Z8803:2011.

[0078] Specific examples of organopolysiloxanes of component (b) include compounds represented by the following general formula: (In the formula, d' is an integer of 1 or more, preferably an integer of 1,000 or more, more preferably an integer of 2,000 or more, and particularly preferably an integer of 3,000 to 10,000. 12 may be the same or different and are a methyl group, a vinyl group, or a hydroxyl group. Me is a methyl group. (In the formula, c' is an integer of 1 or more, d' is an integer of 1 or more, and c'+d' is preferably an integer of 1,000 or more, more preferably an integer of 2,000 or more, and particularly preferably an integer of 3,000 to 10,000. However, c' and d' are numerical values ​​such that the proportion of -CH=CH2 groups in all organic groups bonded to silicon atoms is 0.01 to 15 mol %. 12 may be the same or different and are a methyl group, a vinyl group, or a hydroxyl group. Me is a methyl group. (In the formula, e' is an integer of 1 or more, f' is an integer of 1 or more, g' is an integer of 1 or more, and e' + f' + g' is preferably an integer of 1,000 or more, more preferably an integer of 2,000 or more, and particularly preferably an integer of 3,000 to 10,000. However, e', f', and g' are numerical values ​​such that the proportion of -CH=CH2 groups in all organic groups bonded to silicon atoms is 0.01 to 15 mol %. 13 may be the same or different and are a methyl group, a vinyl group, a 3,3,3-trifluoropropyl group, or a hydroxyl group. Me is a methyl group. (In the formula, e' is an integer of 1 or more, f' is an integer of 1 or more, g' is an integer of 1 or more, and e' + f' + g' is preferably an integer of 1,000 or more, more preferably an integer of 2,000 or more, and particularly preferably an integer of 3,000 to 10,000. However, e', f', and g' are numerical values ​​such that the proportion of -CH=CH2 groups in all organic groups bonded to silicon atoms is 0.01 to 15 mol %. 14 may be the same or different and are a methyl group, a vinyl group, a phenyl group, or a hydroxyl group. Me is a methyl group.

[0079] The organopolysiloxane of component (b) can be produced by known methods, for example, by ring-opening polymerization in the presence of a basic catalyst or an acidic catalyst of a cyclic polysiloxane (a siloxane trimer or tetramer) obtained by (co)hydrolyzing one or more organohalosilanes.

[0080] In the present invention, the mixing ratio of component (a) to component (b) is, in volume ratio, (a):(b)=95:5 to 99:1, preferably 95.1:4.9 to 98.8:1.2, and more preferably 95.5:4.5 to 98.5:1.5. If the volume ratio of component (a) is less than 95, chemical resistance and solvent resistance are insufficient. Furthermore, if the volume ratio of component (a) exceeds 99, roll processability is insufficient. The volume ratio can be determined from the densities of component (a) and component (b) calculated by the method described in JIS K6249:2003.

[0081] [Peroxide Crosslinking Agent] A peroxide crosslinking agent can be used to cure the peroxide-crosslinkable fluororubber composition of the present invention. The peroxide crosslinking agent is not particularly limited, and examples thereof include dibenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butylperoxyisopropyl monocarbonate, and 2,5-dimethyl-2,5-di-t-butylperoxyhexane. From the viewpoints of storage stability and scorch prevention, 2,5-dimethyl-2,5-di-t-butylperoxyhexane is preferred.

[0082] The amount of the peroxide crosslinking agent added may be an amount sufficient to cure the peroxide-crosslinkable fluororubber composition component of the present invention, but when component (A) or component (b) contains an alkenyl group, the amount is preferably 0.1 to 10 parts by mass, particularly 0.5 to 5 parts by mass, per 100 parts by mass of the total of components (A) and (b). If the amount is less than 0.1 part by mass, crosslinking may be insufficient or slow, and if the amount exceeds 10 parts by mass, physical properties may be adversely affected.

[0083] [Other Components] In addition to the components (a) and (b), the peroxide-crosslinkable fluororubber composition of the present invention may optionally contain, in order to enhance its practical utility, fillers other than the reinforcing filler (B), adhesion promoters, plasticizers, viscosity modifiers, flexibility promoters, inorganic pigments such as titanium oxide, iron oxide, carbon black, and cobalt aluminate, heat resistance improvers such as titanium oxide, iron oxide, carbon black, cerium oxide, cerium hydroxide, zinc carbonate, magnesium carbonate, and manganese carbonate, thermal conductivity promoters such as alumina, boron nitride, silicon carbide, and metal powder, and conductivity promoters such as carbon black, silver powder, and conductive zinc oxide. The amounts of these additives may be arbitrarily determined as long as the object of the present invention is not impaired.

[0084] As the plasticizer, viscosity modifier, and flexibility-imparting agent, a non-reactive (non-functional) linear polyfluoro compound represented by the following general formulas (5) and (6), which does not have functional groups (alkenyl groups and hydrosilyl groups) involved in the hydrosilylation reaction in the molecule, can be used.

[0085] F-(CF2CF2CF2O) v' -J (5) (wherein J is C w’ F 2w’+1 -(w' is an integer of 1 to 3), and v' is an integer of 1 to 500, preferably an integer of 2 to 300.

[0086] J-{(OCF(CF3)CF2) x' -(OCF2CF2) y' -(OCF2) z'}-O-J (6) (wherein J is the same as above, x' and y' each represent an integer of 0 to 300, preferably an integer of 0 to 150, except when both x' and y' are 0. In addition, z' represents an integer of 1 to 300, preferably an integer of 1 to 150. The repeating units may be bonded to each other randomly.)

[0087] Specific examples of the linear polyfluoro compound represented by the general formula (5) or (6) include the following: F—(CF2CF2CF2O) v" -CF2CF3 (v" is an integer from 1 to 200) CF3-{(OCF(CF3)CF2) x" -(OCF2) z"}-O-CF3 (x" is an integer of 1 to 200, and z" is an integer of 1 to 200. The repeating units may be bonded to each other randomly.) CF3-{(OCF2CF2) y" -(OCF2) z"}-O-CF3 (wherein y" is an integer of 1 to 200, and z" is an integer of 1 to 200. The repeating units may be bonded randomly.)

[0088] The linear polyfluoro compounds represented by the above general formula (5) or (6) may be used singly or in combination of two or more kinds.

[0089] The peroxide-crosslinkable fluororubber composition of the present invention can be obtained by uniformly kneading the above-mentioned components (a) and (b), and, if necessary, the peroxide crosslinking agent and other components in predetermined amounts. Regarding the kneading method, a two-roll mill, kneader, pressure kneader, Banbury mixer, or the like, which are commonly used in rubber mixing, can be used. Among these, from the viewpoints of workability and productivity, internal kneaders such as pressure kneaders and Banbury mixers are preferred. A particularly preferred kneading method is to knead components (a) and (b) in an internal kneader, and then mix the peroxide crosslinking agent using a two-roll mill.

[0090] The method for molding the peroxide-crosslinkable fluororubber composition of the present invention is not particularly limited, and examples include press molding, compression molding, and injection molding. Curing conditions can be appropriately selected so that the crosslinking reaction is completed. Curing conditions can be set at 100 to 200°C, particularly 120 to 170°C, for 1 minute to 2 hours, particularly 5 minutes to 1 hour. To stabilize the physical properties of the composition, secondary curing is preferably performed by heat treatment at 100 to 230°C for 1 to 24 hours. Secondary curing is less effective at temperatures below 100°C, while temperatures above 230°C may result in thermal decomposition. Curing at 150 to 200°C for 1 to 20 hours is even more preferable.

[0091] The peroxide-crosslinkable fluororubber composition of the present invention has excellent roll processability, and the resulting cured product has excellent heat resistance, chemical resistance, solvent resistance, low-temperature properties, and the like.

[0092] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, the kinematic viscosity of a 10% by mass HFE-7200 (Novec (registered trademark), manufactured by 3M) solution of component (A) is a value measured at 25°C using a Cannon-Fenske viscometer according to the method described in JIS Z8803:2011 using an HFE-7200 (manufactured by 3M) solution. The surface carbon amount of component (B) is a value measured by a known elemental analysis method, the surface alkenyl group amount is a value measured by FT-IR, and the bulk density is a value measured by the tapping method. The viscosity of component (b) is a value measured at 25°C using a 30% by mass toluene solution using a rotational viscometer according to the method described in JIS Z8803:2011, and the degree of polymerization is 1 The amounts of alkenyl groups (vinyl groups) in components (A), (I), and (b) are values ​​measured by H-NMR. 1 The amount of SiH groups in component (II) is a value calculated from the results of analysis such as H-NMR. 1 The values ​​were calculated from the results of analysis such as H-NMR. The room temperature was 25°C. Me in the formula is a methyl group.

[0093] [Examples 1 to 5, Comparative Examples 1 to 3] Components of the compositions used in the examples and comparative examples [Component (a)] (a-1): A perfluoropolyether-based fluororubber mixture prepared by blending 30 parts by mass of the following component (B) with 100 parts by mass of the following component (A-1). (a-2): A perfluoropolyether-based fluororubber mixture prepared by blending 30 parts by mass of the following component (B) with 100 parts by mass of the following component (A-2).

[0094] [Component (A)] (A-1): Addition reaction product obtained by the following method: 100 g of the following component (I-1), 0.94 g of the following component (II-1), and 2.24 g of the following component (II-2) were placed in a 1-liter beaker and thoroughly mixed by hand using a stirring rod at room temperature for 10 minutes. After that, 0.2 g (platinum content 0.2% by mass) of a hydrosilylation reaction catalyst (trade name: CAT-PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was further mixed for 15 minutes. Thereafter, the mixture was heated at 100°C for 1 hour to obtain an addition reaction product (10% by mass HFE-7200 (Novec (registered trademark), manufactured by 3M) solution with a kinematic viscosity of 10 mm 2 / s, alkenyl group content: 4.1 × 10 -3 mol / 100g) was obtained.

[0095] (A-2): Polymer obtained by the following method: 100 g of the following component (I-2), 0.94 g of the following component (II-1), and 2.24 g of the following component (II-2) were placed in a 1-liter beaker and thoroughly mixed by hand using a stirring rod at room temperature for 10 minutes. Then, 0.2 g (platinum content: 0.2% by mass) of a hydrosilylation reaction catalyst (product name: CAT-PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was further mixed for 15 minutes. The mixture was then heated at 100°C for 1 hour to obtain an addition reaction product (10% by mass HFE-7200 (Novec (registered trademark), manufactured by 3M) solution with a kinematic viscosity of 9.8 mm 2 / s, alkenyl group content: 4.0 × 10 -3 mol / 100g) was obtained.

[0096] <Component (I)> (I-1): Perfluoropolyether polymer having alkenyl groups at both ends, represented by the following formula (c+d=90, alkenyl group content: 0.012 mol / 100 g): (I-2): Perfluoropolyether polymer having alkenyl groups at both ends, represented by the following formula (c+d=90, alkenyl group content: 0.012 mol / 100 g)

[0097] <Component (II)> (II-1): Compound represented by the following formula (SiH group content: 4.6×10 -3 mol / g) (II-2): Compound represented by the following formula (SiH group content: 4.6 × 10 -3 mol / g)

[0098] [Component (B)] Hydrophobic fumed silica (BET specific surface area: approximately 200 m) obtained by subjecting A-130 (a hydrophilic fumed silica manufactured by Nippon Aerosil Co., Ltd.) to a surface hydrophobic treatment with a mixed treatment agent of hexamethyldisilazane and 1,3-divinyl-1,1,3,3-tetramethyldisilazane. 2 / g, surface carbon content (carbon content): about 5.0 mass%, surface vinyl group content: 3.00 × 10 -3 mol / 100g, bulk density: approximately 50g / L)

[0099] [Component (b)] (b-1): A rubber-like dimethylpolysiloxane having a 30% by weight toluene solution viscosity (viscosity of a solution in which 30% by weight of organopolysiloxane is dissolved in toluene) of 14,000 mPa·s. (b-2): An oil-like dimethylpolysiloxane having vinyl groups only at both ends of the molecular chain ("VF-600" manufactured by Shin-Etsu Chemical Co., Ltd., degree of polymerization: approximately 180, proportion of vinyl groups in all organic groups bonded to silicon atoms: 0.6 mol%).

[0100] [Peroxide crosslinking agent] 2,5-dimethyl-2,5-di-t-butylperoxyhexane

[0101] Composition Kneading and Molding Conditions (1) Components (a) and (b) were kneaded in a pressure kneader in the amounts shown in the table below to obtain a base compound. (2) A peroxide crosslinking agent was added to the base compound using a 3.5-inch rubber twin roll mill to obtain a final composition. The roll processability during this process was evaluated using the following method. (3) The final composition was crosslinked using a 75-ton rubber press at 150°C for 15 minutes, followed by post-curing at 200°C for 4 hours to obtain a rubber sheet. (4) Using the rubber sheet, normal physical properties were measured in accordance with JIS K 6249. (5) Using the rubber sheet, the rubber sheet was immersed in toluene at 23°C for 72 hours, and the volume swelling ratio was measured in accordance with JIS K 6258.

[0102] [Roll processability evaluation method] 200 g of material was used on two 3.5-inch rubber rolls, and the roll workability was evaluated after 20 minutes of continuous mixing. ◎: No adhesion to the rolls, good roll workability ○: Some adhesion to the rolls is felt, but work can be done without stopping the roll rotation △: Adhesion increases with mixing time, but the material can be peeled off if the roll rotation is stopped ×: Adhesion increases with mixing time, making it difficult to remove the material even when the roll rotation is stopped

[0103]

[0104] From the above results, it can be seen that Examples 1 to 5 exhibited low volume swelling ratios and good roll processability while maintaining good solvent resistance. On the other hand, Comparative Examples 1 and 3, which contained a low or no organopolysiloxane content, exhibited good solvent resistance but poor roll processability. Furthermore, when the organopolysiloxane content in the composition exceeded a certain level, as in Comparative Example 2, roll processability was good, but the volume swelling ratio was high and solvent resistance was poor.

Claims

1. A peroxide-crosslinked fluororubber composition comprising (a) a perfluoropolyether-based fluororubber mixture and (b) an organopolysiloxane, wherein the volume ratio of components (a) and (b) is (a):(b) = 95:5 to 99:

1.

2. The peroxide-crosslinked fluororubber composition according to claim 1, wherein the (a) perfluoropolyether-based fluororubber mixture comprises an addition reaction product of (A) a perfluorinated compound (I) having at least two alkenyl groups in the molecule and a perfluoroalkylene group or a divalent perfluoropolyether group in the main chain, and (II) an organosilicon compound having at least two SiH groups in the molecule, and (B) a reinforcing filler.

3. The (b) organopolysiloxane is an organopolysiloxane represented by the following average composition formula (1) (R 11 ), x SiO (4-x) / 2 (1) (In the formula, R 11 is an unsubstituted or substituted monovalent hydrocarbon group, and x is a number satisfying 1.85 < x < 2.10.) The peroxide-crosslinkable fluororubber composition according to claim 1, which is an organopolysiloxane represented by the formula.

4. The component (I) is represented by the following general formula (2): Rf[−U−Z(−Y−X) β 2 (2) (In the formula, Rf is a perfluoroalkylene group or a divalent perfluoropolyether group, U is independently a single bond, a carbonyl bond, or a divalent organic group, Z is independently a single bond, a nitrogen atom, a silicon atom, a carbon atom, a phosphorus atom, or a trivalent to octavalent organic group, Y is independently a single bond or a divalent organic group, X is independently an alkenyl group, and β is an integer of 1 to 7. However, U and Z are not simultaneously single bonds.) The peroxide crosslinkable fluororubber composition according to claim 2, which is a perfluorinated compound represented by the formula.

5. In the formula (2), Rf is - C a F 2a O - (wherein a is an integer of 1 to 6). The peroxide crosslinkable fluororubber composition according to claim 4, which contains one or more repeating units (perfluorooxyalkylene units) represented by this formula.

6. The component (II) is represented by the following general formula (3): (In the formula, R 4 each independently represents an unsubstituted or substituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond. W represents a divalent organic group.) The peroxide-crosslinkable fluororubber composition according to claim 2, which is an organosilicon compound represented by the formula.

7. In the formula (3), W is a group represented by any of the formulas (i) to (iii). [In the formula, Rf” is a perfluoroalkylene group or a divalent perfluoropolyether group, and R 5 is independently an oxygen atom, or an unsubstituted or substituted divalent hydrocarbon group, and R 6 is independently an unsubstituted or substituted monovalent hydrocarbon group, and R 7 is an unsubstituted or substituted monovalent hydrocarbon group, or a dimethylsiloxy group, D is independently -CH2-, -CH2O-, -CH2OCH2-, -E-NR 8 SO2- or -E-NR 8 -CO- (wherein E is -CH2- or a group represented by the following formula (wherein Me is a methyl group), and R 8 is a hydrogen atom or an unsubstituted or substituted monovalent hydrocarbon group). Rf’ is a monovalent perfluoropolyether group or a perfluoroalkyl group, and z is independently 0 or 1. ] The peroxide crosslinkable fluororubber composition according to claim 6, which is a group represented by any of the above.

8. The peroxide-crosslinked fluororubber composition according to claim 2, wherein the (B) reinforcing filler is a silica-based reinforcing filler, quartz powder, fused quartz powder, diatomaceous earth, or calcium carbonate.

9. A rubber molded article obtained by curing the peroxide-crosslinked fluororubber composition according to any one of claims 1 to 8.

10. A method for producing a peroxide-crosslinked fluororubber composition according to any one of claims 1 to 8, characterized in that components (a) and (b) are kneaded in a closed kneader.

11. The method for producing a peroxide-crosslinked fluororubber composition according to claim 10, wherein the closed kneader is a pressure kneader or a Banbury mixer.

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