sealant

Abstract

The present invention provides a sealing material in which the uncrosslinked rubber composition exhibits excellent crosslinking properties, and the rubber composition after crosslinking exhibits low compression set. [Solution] The sealing material is formed from a rubber composition obtained by crosslinking an uncrosslinked rubber composition. The uncrosslinked rubber composition contains FKM, peroxide, an acidic to neutral reinforcing filler, and a basic filler.

Description

Technical Field

[0001] The present invention relates to a sealing material.

Background Art

[0002] A sealing material formed of a rubber composition in which silica is blended with FKM is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0008] The sealing material according to this embodiment is formed of a rubber composition X obtained by heating and crosslinking an uncrosslinked rubber composition X'. The uncrosslinked rubber composition X' contains FKM, peroxide, an acidic to neutral reinforcing filler, and a basic filler.

[0009] According to the embodiment of the sealing material, the uncrosslinked rubber composition X' before crosslinking the rubber composition X that forms it contains FKM, peroxide, an acidic to neutral reinforcing filler, and a basic filler, thereby enabling excellent crosslinkability of the uncrosslinked rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X that forms the sealing material.

[0010] In this application, "FKM" refers to a copolymer containing one or more monomers from among vinylidene fluoride (VdF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), and perfluoromethyl vinyl ether (PMVE). Examples of FKM include binary FKMs such as the binary copolymer of vinylidene fluoride (VdF) and hexafluoropropylene (HFP), ternary FKMs such as the ternary copolymer of vinylidene fluoride (VdF), hexafluoropropylene (HFP), and tetrapolymers such as the quaternary FKMs such as the quaternary copolymer of 4-bromide-3,3,4,4-tetrafluoro-1-butene, ethylene (E), tetrafluoroethylene (TFE), and perfluoromethyl vinyl ether (PMVE). The FKM preferably includes one or more of the binary FKM, ternary FKM, and quaternary FKM, and more preferably includes binary FKM from the viewpoint of obtaining excellent crosslinking properties of the uncrosslinked rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X that forms the sealing material.

[0011] Examples of peroxides include dialkyl peroxides, peroxyketals, and peroxyesters. Examples of dialkyl peroxides include dicumyl peroxide, 1,3-di(t-butylperoxy)diisopropylbenzene, 1,4-di(t-butylperoxy)diisopropylbenzene, t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane-3. Examples of peroxyketals include 1,1-di(t-hexylperoxy)cyclohexane, 1,1-di(t-butylperoxy)cyclohexane, and n-butyl-4,4-di(t-butylperoxy)valerate. Examples of peroxyesters include 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-hexylperoxybenzoate, and t-butylperoxybenzoate. The peroxide preferably contains one or more of these, and more preferably contains dialkyl peroxide and / or peroxyester, and even more preferably contains 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and / or t-butylperoxybenzoate, from the viewpoint of obtaining excellent crosslinking properties of the uncrosslinked rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X that forms the sealing material.

[0012] The peroxide content A in the uncrosslinked rubber composition X' is preferably 0.5 to 3 parts by mass, more preferably 1 to 2 parts by mass, per 100 parts by mass of FKM, from the viewpoint of obtaining excellent crosslinkability of the uncrosslinked rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X that forms the sealing material.

[0013] The reinforcing filler is acidic to neutral. "Acidic to neutral" means that the pH of the dispersion obtained by dispersing the reinforcing filler in water is 7 or less. Examples of reinforcing fillers include acidic to neutral fumed silica, acidic to neutral carbon black, and acidic to neutral resin powder. Examples of acidic to neutral fumed silica include untreated hydrophilic fumed silica, hydrophobic fumed silica surface-treated with dimethyldichlorosilane, hydrophobic fumed silica surface-modified with trimethylsilyl groups, hydrophobic fumed silica surface-treated with octylsilane, and hydrophobic fumed silica surface-treated with dimethyl silicone oil. The reinforcing filler preferably contains one or more of these types, and more preferably contains acidic to neutral fumed silica, and even more preferably contains hydrophobic fumed silica surface-treated with dimethyldichlorosilane, from the viewpoint of obtaining excellent crosslinkability of the uncrosslinked rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X that forms the sealing material. The average particle size of the reinforcing filler is, for example, 10 μm to 20 μm. In the case of acidic to neutral fumed silica, its specific surface area by the BET method is, for example, 70 m². 2 / g or more 150m 2 It is / g.

[0014] The amount of reinforcing filler B in the uncrosslinked rubber composition X' is preferably 3 to 25 parts by mass, more preferably 5 to 15 parts by mass, and even more preferably 10 to 12 parts by mass, per 100 parts by mass of FKM, from the viewpoint of obtaining excellent crosslinkability of the uncrosslinked rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X that forms the sealing material.

[0015] Basic fillers are basic. This "basicity" means that the pH of the dispersion obtained by dispersing the basic filler in water is greater than 7. Examples of basic fillers include hydrophobic fumed silica surface-modified with basic groups such as amino groups, basic wet silica, basic phenolic resin powder, metal oxide powder, and powdered metal hydroxide. It is preferable that the basic filler contains one or more of these, and it is more preferable to include hydrophobic fumed silica and / or basic wet silica surface-modified with basic groups, from the viewpoint of obtaining excellent crosslinkability of the uncrosslinked rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X that forms the sealing material. The average particle size of the basic filler is, for example, 5 μm to 15 μm. In the case of hydrophobic fumed silica and basic wet silica surface-modified with basic groups, their specific surface area by the BET method is, for example, 100 m². 2 / g or more 200m 2 It is less than / g.

[0016] The basic filler content C in the uncrosslinked rubber composition X' is preferably 0.1 parts by mass or more and 3 parts by mass or less, more preferably 0.3 parts by mass or more and 1.5 parts by mass or less, and even more preferably 0.5 parts by mass or more and 1 part by mass or less, per 100 parts by mass of FKM, from the viewpoint of obtaining excellent crosslinkability of the uncrosslinked rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X that forms the sealing material.

[0017] The content B of the reinforcing filler in the uncrosslinked rubber composition X' is preferably greater than the content C of the basic filler, from the viewpoint of obtaining excellent crosslinkability of the uncrosslinked rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X that forms the sealing material. From the same viewpoint, the mass ratio of the reinforcing filler content B to the basic filler content C in the uncrosslinked rubber composition X' is preferably 4 to 50, more preferably 5 to 40, and even more preferably 10 to 25.

[0018] The sum of the reinforcing filler content B and the basic filler content C in the uncrosslinked rubber composition X' is preferably 3 to 30 parts by mass, more preferably 5 to 20 parts by mass, and even more preferably 10 to 15 parts by mass, per 100 parts by mass of FKM, from the viewpoint of obtaining excellent crosslinkability of the uncrosslinked rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X that forms the sealing material.

[0019] The uncrosslinked rubber composition X' may further contain a crosslinking aid. Examples of crosslinking aids include triallyl cyanurate, trimethyl isocyanurate, triallyl isocyanurate, triacrylic formal, triallyl trimellitate, N,N'-m-phenylene bismaleimide, dipropagyl terephthalate, diallyl phthalate, tetraallyl terephthalate amide, triallyl phosphate, bismaleimide, and fluorinated triallyl isocyanurate (1,3,5-tris(2,3,3-trifluoro-2-propenyl)-1,3,5-triazine). Examples include (-2,4,6-trione), tris(diallylamine)-S-triazine, triallyl phosphite, N,N-diallylcrylamide, 1,6-divindodecafluorohexane, hexaarylphosphoramide, N,N,N',N'-tetraallylphthalamide, N,N,N',N'-tetraallylmalonamide, trivinyl isocyanurate, 2,4,6-trivinylmethyltrisiloxane, tri(5-norbornene-2-methylene)cyanurate, and triallyl phosphite. The crosslinking aid preferably contains one or more of these, and more preferably contains triallyl isocyanurate from the viewpoint of obtaining excellent crosslinkability of the uncrosslinked rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X that forms the sealing material.

[0020] The content D of the crosslinking aid in the unvulcanized rubber composition is preferably 1 to 10 parts by mass, more preferably 3 to 5 parts by mass, per 100 parts by mass of FKM, from the viewpoint of obtaining excellent crosslinkability of the unvulcanized rubber composition X' and reducing the compression set CS of the crosslinked rubber composition X forming the sealing material.

[0021] The unvulcanized rubber composition X' may contain, among other things, rubber components other than FKM, plasticizers, processing aids, vulcanization accelerators, antioxidants, surfactants, etc.

[0022] Based on JIS K6300-2:2001 of the unvulcanized rubber composition X', by the die vulcanization test A method using a torsional vibration type flat die vulcanization tester (for example, Curemeter (registered trademark) manufactured by ENEOS MATERIAL TRADING CO., LTD.), the time (t90) from the start of vulcanization until 90% of the maximum torque is obtained from the vulcanization curve obtained with the heating temperature (primary crosslinking temperature) of the unvulcanized rubber composition X' as the test temperature is preferably 7 minutes or less, more preferably 5 minutes or less, and still more preferably 3 minutes or less, from the viewpoint of obtaining excellent crosslinkability of the unvulcanized rubber composition X'.

[0023] The sealing material according to the embodiment can be produced by molding the unvulcanized rubber composition X' into the shape of a sealing material and heating and crosslinking it to obtain the rubber composition X.

[0024] Specifically, first, an uncrosslinked rubber composition X' is prepared by kneading using an open-type rubber kneader such as an open roll kneader, or a closed-type rubber kneader such as a kneader. Next, a predetermined amount of the uncrosslinked rubber composition X' is filled into a cavity shaped like a seal material in a preheated mold and the mold is clamped. In this state, primary crosslinking is performed by heating while maintaining a predetermined temperature and pressure for a predetermined time. This primary crosslinking may be performed by press molding or by injection molding. The primary crosslinking temperature is, for example, 150°C to 180°C. The primary crosslinking pressure is, for example, 0.1 MPa to 25 MPa. The primary crosslinking time is, for example, 3 minutes to 20 minutes. Then, the mold is opened and the seal material formed from the crosslinked rubber composition X is demolded and removed from the inside.

[0025] Alternatively, the sealing material of the molded product, after being demolded from the mold, may be placed in a preheated oven and heated at a predetermined temperature for a predetermined time to induce secondary crosslinking. The secondary crosslinking temperature is higher than the primary crosslinking temperature, for example, between 190°C and 210°C. The secondary crosslinking time is longer than the primary crosslinking time, for example, between 3 hours and 5 hours.

[0026] Furthermore, post-crosslinking may be performed by irradiating the sealing material with radiation after primary or secondary crosslinking. In this case, examples of radiation include alpha rays, beta rays, gamma rays, electron beams, and ions. Of these, electron beams or gamma rays are preferred. The radiation dose is, for example, 20 kGy or more and 100 kGy or less.

[0027] The hardness HA of the rubber composition X forming the sealing material according to the embodiment is preferably A65 or more and A75 or less, more preferably A68 or more and A72 or less. This hardness HA is measured using a Type A durometer in accordance with JIS K6253-3:2012.

[0028] The tensile strength Tb at break of rubber composition X is preferably 15 MPa or more, more preferably 25 MPa or more. The elongation Eb at break is preferably 400% or more, more preferably 500% or more. The 100% modulus S100 (tensile stress at 100% elongation) is preferably 1.5 MPa or more and 3 MPa or less, more preferably 2 MPa or more and 2.5 MPa or less. These tensile strength Tb at break, elongation Eb at break, and 100% modulus S100 are measured by a tensile test based on JIS K6251:2023.

[0029] The compression set CS of the rubber composition X is preferably 30% or less, more preferably 20% or less, and even more preferably 15% or less. This compression set CS is measured according to JIS K6262:2013 with a test time of 72 hours and a test temperature of 200°C.

[0030] The sealing material according to the embodiment preferably has a surface color that is not black, such as beige, brown, or dark brown. [Examples]

[0031] (Uncrosslinked rubber composition) The following crosslinked rubber compositions were prepared as examples and comparative examples. Their respective compositions are also shown in Tables 1 to 5.

[0032] <Example 1-1> 100 parts by mass of binary FKM (Daiel® G801, manufactured by Daikin Corporation), 1.5 parts by mass of peroxide 1 (2,5-dimethyl-2,5-di(t-butylperoxy)hexane) (Perhexa® 25B, manufactured by NOF Corporation), and hydrophobic fumed silica (Aerosil® R972, manufactured by Nippon Aerosil Co., Ltd., specific surface area by BET method: 90-130 m²) surface-treated with dimethyldichlorosilane as a reinforcing filler. 2 / g, average particle size (primary): 16 μm) 11.7 parts by mass, wet silica (Carplex® #1120, manufactured by DSL Japan, with basic filler 1, specific surface area by BET method: 120 m²) 2An uncrosslinked rubber composition was prepared by mixing 0.3 parts by mass of (average particle size (primary): 12 μm) and 4 parts by mass of triallyl isocyanurate (TAIC®, manufactured by Mitsubishi Chemical Corporation) as a crosslinking aid, and kneading the mixture. This was designated as Example 1-1.

[0033] <Examples 1-2 to 1-4 and Comparative Example 1> An uncrosslinked rubber composition was prepared in the same manner as in Example 1-1, except that the amounts of reinforcing filler and basic filler 1 were 11.5 parts by mass and 0.5 parts by mass, respectively, per 100 parts by mass of binary FKM, and this was designated as Example 1-2.

[0034] An uncrosslinked rubber composition was prepared in the same manner as in Example 1-1, except that the amounts of reinforcing filler and basic filler 1 were 11.3 parts by mass and 0.7 parts by mass, respectively, per 100 parts by mass of binary FKM, and this was designated as Example 1-3.

[0035] An uncrosslinked rubber composition was prepared in the same manner as in Example 1-1, except that the amounts of reinforcing filler and basic filler 1 were 11.0 parts by mass and 1.0 part by mass, respectively, per 100 parts by mass of binary FKM, and this was designated as Example 1-4.

[0036] An uncrosslinked rubber composition was prepared in the same manner as in Example 1-1, except that basic filler 1 was not included and the amount of reinforcing filler was 12.0 parts by mass per 100 parts by mass of binary FKM, and this was designated as Comparative Example 1.

[0037] [Table 1]

[0038] <Examples 2-1 to 2-5 and Comparative Example 2> Hydrophobic fumed silica (Aerosil® R504, manufactured by Nippon Aerosil Co., Ltd., with surface modification of amino and trimethylsilyl groups of basic filler 2 instead of basic filler 1; specific surface area by BET method: 125-175 m²) 2An uncrosslinked rubber composition was prepared in the same manner as in Example 1-1, except that the amount of reinforcing filler and basic filler 2 was 11.5 parts by mass and 0.5 parts by mass, respectively, per 100 parts by mass of binary FKM, using ( / g, average particle size (primary): 12 μm), and this was designated as Example 2-1.

[0039] An uncrosslinked rubber composition was prepared in the same manner as in Example 2-1, except that the amounts of reinforcing filler and basic filler 2 were 11.0 parts by mass and 1.0 part by mass, respectively, per 100 parts by mass of binary FKM, and this was designated as Example 2-2.

[0040] An uncrosslinked rubber composition was prepared in the same manner as in Example 2-1, except that the amounts of reinforcing filler and basic filler 2 were 10.5 parts by mass and 1.5 parts by mass, respectively, per 100 parts by mass of binary FKM, and this was designated as Example 2-3.

[0041] An uncrosslinked rubber composition was prepared in the same manner as in Example 2-2, except that t-butyl peroxybenzoate (Perbutyl® Z, manufactured by NOF Corporation), which is peroxide 2, was used instead of peroxide 1, and the amount of peroxide used was 1 part by mass per 100 parts by mass of the binary FKM. This was designated as Example 2-4.

[0042] An uncrosslinked rubber composition was prepared in the same manner as in Example 2-3, except that peroxide 2 was used instead of peroxide 1, and its amount was 1 part by mass per 100 parts by mass of binary FKM. This was designated as Example 2-5.

[0043] An uncrosslinked rubber composition was prepared in the same manner as in Example 2-1, except that no reinforcing filler was added and the amount of basic filler 2 was set to 10.0 parts by mass per 100 parts by mass of binary FKM. This was designated as Comparative Example 2-1.

[0044] [Table 2]

[0045] <Examples 3-1 to 3-3> An uncrosslinked rubber composition was prepared in the same manner as in Example 1-1, except that basic phenol resin powder (Bellpearl® R200, manufactured by Air Water Performance Chemicals, average particle size: 6 μm) of basic filler 1 was used instead of basic filler 1, and the amounts of reinforcing filler and basic filler 3 were set to 11.5 parts by mass and 0.5 parts by mass, respectively, per 100 parts by mass of binary FKM. This was designated as Example 3-1.

[0046] An uncrosslinked rubber composition was prepared in the same manner as in Example 3-1, except that the amounts of reinforcing filler and basic filler 3 were 11.0 parts by mass and 1.0 part by mass, respectively, per 100 parts by mass of binary FKM, and this was designated as Example 3-2.

[0047] An uncrosslinked rubber composition was prepared in the same manner as in Example 3-1, except that the amounts of reinforcing filler and basic filler 3 were 10.5 parts by mass and 1.5 parts by mass, respectively, per 100 parts by mass of binary FKM, and this was designated as Example 3-3.

[0048] [Table 3]

[0049] <Examples 4-1 to 4-4 and Comparative Examples 4-1 to 4-2> An uncrosslinked rubber composition was prepared in the same manner as in Example 2-1, except that a ternary FKM (Solvay® PX989S, manufactured by Solvay Japan) was used instead of a binary FKM, and the amounts of reinforcing filler and basic filler 2 were set to 9.0 parts by mass and 1.0 part by mass, respectively, per 100 parts by mass of ternary FKM. This was designated as Example 4-1.

[0050] An uncrosslinked rubber composition was prepared in the same manner as in Example 4-1, except that the amounts of reinforcing filler and basic filler 2 were 8.5 parts by mass and 1.5 parts by mass, respectively, per 100 parts by mass of ternary FKM, and this was designated as Example 4-2.

[0051] An uncrosslinked rubber composition was prepared in the same manner as in Example 4-1, except that peroxide 2 was used instead of peroxide 1, and its amount was 1 part by mass per 100 parts by mass of ternary FKM. This was designated as Example 4-3.

[0052] An uncrosslinked rubber composition was prepared in the same manner as in Example 4-2, except that peroxide 2 was used instead of peroxide 1, and its amount was 1 part by mass per 100 parts by mass of ternary FKM. This was designated as Example 4-4.

[0053] An uncrosslinked rubber composition was prepared in the same manner as in Example 4-1, except that basic filler 2 was not included and the amount of reinforcing filler was 10.0 parts by mass per 100 parts by mass of ternary FKM. This was designated as Comparative Example 4-1.

[0054] An uncrosslinked rubber composition was prepared in the same manner as in Example 4-3, except that basic filler 2 was not included and the amount of reinforcing filler was 10.0 parts by mass per 100 parts by mass of ternary FKM. This was designated as Comparative Example 4-2.

[0055] [Table 4]

[0056] <Examples 5-1 to 5-2 and Comparative Example 5> An uncrosslinked rubber composition was prepared in the same manner as in Example 2-4, except that a quaternary FKM (Viton® VTR9213, manufactured by Chemours) was used instead of a binary FKM, and the amounts of reinforcing filler and basic filler 2 were set to 8.5 parts by mass and 1.5 parts by mass, respectively, per 100 parts by mass of quaternary FKM. This was designated as Example 5-1.

[0057] An uncrosslinked rubber composition was prepared in the same manner as in Example 5-1, except that the amounts of reinforcing filler and basic filler 2 were 8.0 parts by mass and 2.0 parts by mass, respectively, per 100 parts by mass of quaternary FKM, and this was designated as Example 5-2.

[0058] An uncrosslinked rubber composition was prepared in the same manner as in Example 5-1, except that basic filler 2 was not included and the amount of reinforcing filler was 10.0 parts by mass per 100 parts by mass of quaternary FKM. This was designated as Comparative Example 5.

[0059] [Table 5]

[0060] (Rubber sheets for test specimens and test specimens for compression set testing) For each of the uncrosslinked rubber compositions in the above examples and comparative examples, primary crosslinking was performed by placing them in a mold for rubber sheet molding, setting them in a press molding machine, and heating and pressurizing them. The primary crosslinking temperature was 165°C for those using peroxide 1 and 155°C for those using peroxide 2. The primary crosslinking time was 10 minutes. The primary crosslinked material was demolded from the mold and heated in an oven at a temperature of 200°C for 4 hours to induce secondary crosslinking, thereby producing rubber sheets for test specimens. Similarly, test specimens for compression set testing were prepared.

[0061] (Test methods and results) The following tests were performed on the uncrosslinked rubber compositions of the above examples and comparative examples, as well as on the rubber sheets and compression set test specimens prepared by crosslinking them. The test results are shown in Tables 1 to 5. In Comparative Example 4-1, the crosslinking of the uncrosslinked rubber composition did not proceed, and a crosslinked rubber composition could not be obtained.

[0062] <t90> For each of the uncrosslinked rubber compositions in the above examples and comparative examples, the time (t90) from the start of vulcanization to obtaining 90% of the maximum torque was determined from the vulcanization curve obtained by die vulcanization test method A using a torsional vibration type flat plate die vulcanization tester (Curlastometer®, manufactured by ENEOS Material Trading Co., Ltd.) in accordance with JIS K6300-2:2001. The test temperature was 165°C for those using peroxide 1 and 155°C for those using peroxide 2.

[0063] <Hardness> Test specimens were prepared by crosslinking each of the uncrosslinked rubber compositions of the above examples and comparative examples, and the rubber sheets were stacked to form test specimens. The hardness was measured using a Type A durometer in accordance with JIS K6253-3:2012.

[0064] <density> Test specimens were cut from rubber sheets prepared by crosslinking each of the uncrosslinked rubber compositions of the above examples and comparative examples, and their density was measured according to JIS K6268:1998.

[0065] <Tensile properties> Test specimens were cut from rubber sheets prepared by crosslinking each of the uncrosslinked rubber compositions of the above examples and comparative examples, and the tensile strength Tb at break, elongation Eb at break, and 100% modulus S100 (tensile stress at 100% elongation) were measured according to JIS K6251:2023.

[0066] <Compression set> For the compression set test specimens prepared by crosslinking each of the uncrosslinked rubber compositions of the above examples and comparative examples, the compression set CS was measured according to JIS K6262:2013, with a test time of 72 hours and a test temperature of 200°C.

[0067] <Surface color tone> The surface color of the test specimen rubber sheets, prepared by crosslinking each of the uncrosslinked rubber compositions described in Examples 1-1 to 1-4, Comparative Example 1, Examples 2-1 to 2-3, Comparative Example 2, and Examples 3-1 to 3-3, was evaluated visually. [Industrial applicability]

[0068] This invention is useful in the field of sealing materials.

Claims

1. A sealing material formed from a rubber composition that is crosslinked by heating an uncrosslinked rubber composition, The aforementioned uncrosslinked rubber composition is a sealing material containing FKM, peroxide, an acidic to neutral reinforcing filler, and a basic filler.

2. In the sealing material described in claim 1, The aforementioned FKM is a sealing material containing a binary FKM.

3. In the sealing material described in claim 1, The sealant comprises 2,5-dimethyl-2,5-di(t-butylperoxy)hexane and / or t-butylperoxybenzoate as the peroxide.

4. In the sealing material described in claim 1, The aforementioned reinforcing filler is a sealing material containing acidic to neutral fumed silica.

5. In the sealing material described in claim 1, The basic filler comprises one or more of the following: fumed silica, basic wet silica, and basic phenolic resin powder, all of which are surface-modified with basic groups.

6. In the sealing material described in claim 1, A sealing material wherein the content of the basic filler in the uncrosslinked rubber composition is 3 parts by mass or less per 100 parts by mass of the FKM.

7. In the sealing material described in claim 1, A sealing material in which the time from the start of vulcanization to obtaining 90% of the maximum torque, as determined from the vulcanization curve obtained by die vulcanization test method A based on JIS K6300-2:2001 for the uncrosslinked rubber composition, is 7 minutes or less.

8. In the sealing material described in claim 1, A sealing material having a hardness of A65 or more and A75 or less as measured by a Type A durometer according to JIS K6253-3:2012 for the rubber composition.

9. In the sealing material described in claim 1, A sealing material having a compression set of 30% or less, measured according to JIS K6262:2013 for a test period of 72 hours and a test temperature of 200°C for the rubber composition.

10. In the sealing material described in claim 1, A sealing material having a non-black surface color.

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