WO2006040944A1 - Fluorine rubber composition - Google Patents

Abstract

Disclosed is a fluorine rubber composition exhibiting sealing properties at high temperatures while having adequate cracking resistance and processability at the same time. Also disclosed is a sealing material obtained by vulcanization molding of such a fluorine rubber composition. Further disclosed is a sealing material for oxygen sensors. Specifically disclosed is a rubber composition composed of a fluorine rubber and a vulcanizing agent wherein 0.5-1.7 parts by weight of the vulcanizing agent is contained per 100 parts by weight of the fluorine rubber in the composition and the Mooney viscosity (ML1 + 20, 140˚C) of the fluorine rubber in the composition is 70-150.

Description

 Specification

 Fluoro rubber composition

 Technical field

 [0001] The present invention relates to a fluororubber composition, a sealing material obtained by vulcanization molding the composition, and further a sheath material for an oxygen sensor.

 Background art

 [0002] An oxygen sensor (o) for detecting oxygen concentration, which is one of the uses of the rubber yarn composition of the present invention.

 2 sensor) is used, for example, to detect the oxygen concentration in the exhaust gas generated by the power of an internal combustion engine of an automobile. Although oxygen sensors for automobiles are usually protected by metal or the like, they are attached to high-temperature exhaust pipes, etc., and the inside of the sensor is exposed to a high-temperature exhaust gas stream containing a large amount of oxidizing substances. It must be excellent in chemical properties.

[0003] Oxygen sensors for automobiles are often mounted on the underside of the vehicle body floor, such as those mounted downstream of a catalyst that purifies exhaust gas and those that require detection of catalyst deterioration. In this case, since the oxygen sensor for automobiles is subject to external impacts such as vibration shock from the engine and road surface, stone splashes, and water, it must have mechanical shock resistance, thermal shock resistance, waterproofness, etc. Is also required

[0004] An automobile oxygen sensor is usually cylindrical, and introduces the oxygen concentration detection element at the back of the cylinder to the outside by introducing the oxygen concentration reference air into the oxygen concentration detection section of the oxygen sensor. Several lead wires are built in for removal. The lead wire is arranged so as to penetrate a sealing material called a bush in order to fix the lead wire from the oxygen sensor for automobiles without contacting each other.

 [0005] This sealing material usually has a cylindrical shape as a basic shape. In use, the sealing material has a diameter after passing through a through-hole extending in the height direction of several cylindrical columns provided in advance. Perform caulking to increase pressure in the direction. In the present specification, the radial direction means a direction of the force perpendicular to the center line in the height direction of the cylinder from the side surface of the cylinder.

[0006] It is desirable that this sealing material has elasticity so that it is compressed to some extent by caulking, to securely fix the lead wire, and to exhibit sealing properties such as waterproofness and airtightness. From the installation location, it is desirable to have characteristics such as heat resistance and impact resistance as well as the oxygen sensor body for automobiles. Therefore, as a sealing material, conventionally, a sealing material obtained by vulcanizing and molding a fluororubber composition having these characteristics and also having a fluoro rubber strength has been used.

 [0007] On the other hand, as a sealing material, it is desirable that the compression set is small so as to exhibit excellent sealing characteristics. However, with conventional fluororubber compositions, it has been possible to reduce the compression set of the sealing material by increasing the crosslink density by increasing the amount of vulcanizing agent added. On the other hand, there was a problem that the cracking property caused by was bad. Conversely, it is possible to improve the cracking property of the sealing material by reducing the crosslinking density by reducing the amount of vulcanizing agent, but the compression set of the sealing material increases, so a high-dimensional balance is taken to satisfy both. It was impossible.

 [0008] As a technique for solving these problems, a rubber composition in which the compounding ratio of various additives to be added to the fluororubber is defined (for example, JP-A-9-188793 and JP-A-2001-192482). Issue gazette). However, both were insufficient to satisfy both compression set and crackability at the same time.

 [0009] Further, it comprises a copolymer obtained from a monomer component containing bi-lidene fluoride, tetrafluoroethylene and hexafluoropropylene, and has a weight average molecular weight of 400,000 to 700,000. A sealing material made of a composition containing a certain fluorine-containing elastomer is disclosed (for example, see pamphlet of International Publication No. 03Z074625). However, the processability of fluoroelastomers and fluoroelastomer yarns and composites in which the compression set of the sealant is not sufficient is poor in fluidity, so that the viscosity of the rubber cannot be measured. There was a problem that couldn't be done.

 [0010] Further, in recent years, with higher performance of engines and equipment and higher awareness of environmental protection, more accurate sensor control has been demanded. The sensor mounting position is shifting to the upstream side of the exhaust gas flow, but the exhaust gas flow is hotter toward the upstream side.

[0011] Further, as the interior of an automobile engine room becomes denser, it is desired to reduce the size of the engine in order to expand the indoor living space. The downsizing of the engine contributes to reducing the weight and fuel consumption of automobiles, so the demand for development is high, but the inside of the engine is hot. That Some oxygen sensors are installed in such high-temperature areas.

 Therefore, conventionally, as the temperature becomes higher, the cracking property under high compression and the compression set resistance tend to be deteriorated. Even in the usage environment, it has been demanded that these characteristics are not impaired.

 Disclosure of the invention

 [0013] The present invention provides a fluororubber composition having both high temperature sealability, crackability, and processability, a seal material obtained by vulcanizing the composition, and a seal material for an oxygen sensor.

 [0014] That is, the present invention is a rubber composition having fluororubber and vulcanizing power, and the vulcanizing agent is 0.5 to 1.7 parts by weight with respect to 100 parts by weight of the fluororubber in the composition. And a rubber composition having a Mu-one viscosity (MLl + 20, 140 ° C.) force of 70 to 150 of the fluororubber in the composition.

 [0015] It is preferable that the fluoro rubber has a mu-one viscosity (ML1 + 20, 140 ° C) force of 100 to 150.

 [0016] The fluororubber is preferably a fluororubber containing a bilidene fluoride unit.

[0017] It is preferable that the fluororubber is a binary fluororubber composed of a bilidene fluoride unit and a hexafluoropropylene unit.

[0018] The compounding amount of the vulcanizing agent with respect to 100 parts by weight of fluororubber is X (parts by weight), and the compression set at 25% compression of P-24 · 0 ring at 280 ° CX for 72 hours is Υ (%). Sometimes 20Χ

It is preferable to meet + Υ≤70.

[0019] The vulcanizing agent is preferably a polyhydroxy compound.

 [0020] It is preferable to contain 5 to 30 parts by weight of a bituminous coal filler with respect to 100 parts by weight of the fluororubber.

 [0021] The present invention also relates to a sealing material obtained by vulcanizing the rubber composition.

 [0022] After the vulcanization molding, it is preferable to heat-treat at a temperature of 280 ° C or higher for 1 hour or longer.

 [0023] P—The compression set at 25% compression of the 24 · 0 ring at 280 ° CX for 72 hours is Υ (%), and the cracking rate at 50% compression of the same ring at 280 ° CX for 1 hour is Ζ (% ) And 1

It is preferable to satisfy ΟΥ + Ζ≤500. [0024] The present invention also relates to a sealing material for an oxygen sensor that is also the sealing material.

 [0025] Further, the present invention relates to a sealing material for an oxygen sensor obtained by vulcanizing a rubber composition comprising a fluororubber and a vulcanizing agent. ML1 + 20,

The present invention relates to a sealing material for oxygen sensor whose 140 ° C) is 70 to 150.

 BEST MODE FOR CARRYING OUT THE INVENTION

[0026] The present invention is a rubber composition comprising a fluororubber and a vulcanizing agent,

 The vulcanizing agent is 0.5 to 1.7 parts by weight with respect to 100 parts by weight of the fluororubber in the composition, and the mu-one viscosity (ML1 + 20, 140) of the fluororubber in the composition. ° C) relates to a rubber composition having a force of 0 to 150.

 [0027] Examples of the fluororubber include perfluorofluororubber and non-perfluorofluororubber.

 [0028] Perfluorofluororubber includes tetrafluoroethylene (hereinafter referred to as TFE) Z perfluoro (alkyl butyl ether) (hereinafter referred to as PAVE) copolymer, TFEZ hexafluoropropylene. (Hereinafter referred to as HFP) ZPAVE copolymer and the like.

 [0029] Examples of the non-perfluorofluororubber include a bi-lidene fluoride (hereinafter referred to as VdF) polymer, a TFEZ propylene copolymer, and the like. Any combination can be used within a range without impairing the effects of the invention.

 [0030] In addition, those exemplified as the perfluoro fluororubber and the non-perfluorofluororubber are main monomers, and those obtained by copolymerizing a crosslinking monomer, a modified monomer, and the like can also be suitably used. As the crosslinking monomer or the modifying monomer, a known crosslinking monomer such as an iodine atom, bromine atom, or one containing a double bond, a transfer agent, a modified monomer such as a known ethylenically unsaturated compound, or the like may be used. it can.

[0031] Specific examples of the VdF polymer include a VdFZHFP copolymer, a VdF / TFE ZHFP copolymer, a VdFZTFEZ propylene copolymer, a VdFZ ethylene ZHFP copolymer, and a VdFZTFEZPAVE copolymer. Examples thereof include VdFZPAVE copolymer, VdF Z chlorofluoroethylene (hereinafter referred to as CTFE) copolymer, and the like. More specifically, 25 to 85 mol% of VdF and at least one copolymerizable with VdF More preferably, it is a fluorine-containing copolymer having a strength of 75 to 15 mol% of other monomers, more preferably 50 to 80 mol% of VdF, and at least one other monomer copolymerizable with VdF. This is a fluorine-containing copolymer having a strength of 50 to 20 mol%.

 Here, as at least one other monomer copolymerizable with VdF, for example, TFE, CTFE, trifluoroethylene, HFP, trifluoropropylene, tetrafluoropropylene, penta Examples include fluorine-containing monomers such as fluoropropylene, trifluorobutene, tetrafluoroisobutene, PAVE, and fluorinated butyl, and non-fluorine monomers such as ethylene, propylene, and alkyl butyl ether. These can be used alone or in any combination.

[0033] Among the fluororubbers, from the viewpoint of heat resistance, compression set, workability, and cost, it is preferable to use a fluororubber containing VdF units. From the viewpoint of good compression set, VdF units and HFP More preferably, it is a binary fluororubber having a unit force. Incidentally, the binary fluororubber, be that the sum of VdF unit and HFP unit is 90 mole _^0/0 or more than is preferred instrument 95 mol% or more it is more preferred instrument 100 mol% Particularly preferred.

 [0034] Mu-one viscosity (ML1 + 20, 140.C) of the fluororubber in the rubber composition of the present invention is 70 to 150, and is a force of 80 to 150 S, preferably 90 to 150 The force S is more preferable, and it is more preferably 100 to 150. If the fluoro rubber has a Mu-viscosity of less than 70, it tends to be impossible to provide a good balance between compression set and cracking properties under high temperature and high compression conditions. Above this, molding tends to be difficult. In general, products whose mu-one viscosity is adjusted to 60 are sold and widely used, but fluorine that combines sealing, cracking and workability under high temperature and high compression conditions. This range is insufficient for constituting a rubber composition, and it is necessary to select the Mooney viscosity in the above-mentioned region which is not generally used.

 Here, Mu-one viscosity is a value obtained by measuring using a Mu-one viscosity measuring device (manufactured by MV2000E ALPHA TECHNOLOGIES) in accordance with JIS K 6300 (1994). . The measurement conditions are the values measured using a L-shaped rotor at 140 ° C with a preheating time of 1 minute and a measurement time of 20 minutes.

[0036] In the present invention, the fluororubber in the rubber composition may be one type, or two or more types. It may be combined, but in the case of two or more types, it is only necessary that the mu-one viscosity of the combined fluororubber is within the above predetermined range. Specifically, for example, even when mu-viscosity 60 fluoro rubber and 160 fluoro-rubber are blended to obtain mu-viscosity 110, they are within the scope of the present invention.

 [0037] The rubber composition of the present invention is obtained by blending a vulcanizing agent with the fluororubber. Also, vulcanization accelerators can be used with vulcanizing agents.

 [0038] The vulcanizing agent and the vulcanization accelerator are used for vulcanizing the fluororubber.

 Here, the vulcanization means that the same or different polymer chains of fluororubber are cross-linked by a vulcanizing agent, and the fluororubber is improved in tensile strength by being cross-linked in this way. It can be set as the sealing material of this invention which has elasticity.

 [0039] When the fluorinated rubber contains a crosslinkable group (cure site), the vulcanization system used in the present invention may be appropriately selected depending on the type of cure site or the use of the obtained sealing material. . As the vulcanization system, any of a polyol vulcanization system, a peroxide vulcanization system and a polyamine vulcanization system can be adopted.

 [0040] Here, the vulcanized fluororubber vulcanized by a polyol vulcanization system has a carbon-oxygen bond at the cross-linking point, has a small compression set, a good moldability, and an excellent sealing property. If so, it is suitable for the sealing material of the present invention.

 [0041] Since the vulcanized fluororubber vulcanized by the peroxide vulcanization system has a carbon-carbon bond at the crosslinking point, a polyol vulcanization system having a carbon-oxygen bond at the crosslinking point and a carbon-nitrogen double Excellent chemical resistance and steam resistance compared to polyamine vulcanization systems with bonds! / When you talk! There is a characteristic.

 [0042] A vulcanized fluororubber vulcanized by polyamine vulcanization has a carbon-nitrogen double bond at the cross-linking point and is characterized by excellent dynamic mechanical properties. However, compression set, which is the most important physical property of sealing materials, tends to be larger than vulcanized fluoro rubbers vulcanized using polyol vulcanization system or peroxide vulcanization system vulcanizing agent. .

[0043] Therefore, it is preferable to use a polyol vulcanization or peroxide vulcanization vulcanizing agent as the rubber composition of the present invention. It is more preferable to use an all vulcanizing agent.

 [0044] As the vulcanizing agent in the present invention, polyamine-based, polyol-based and peroxide-based vulcanizing agents generally known for fluoro rubbers can be used.

 [0045] Examples of the polyamine vulcanizing agent include hexamethylenediamine amine carbamate, N, N'-dicinnamylidene 1,6 hexamethylenediamine, 4, 4'-bis (aminocyclohexenole) methane Examples include polyamine compounds such as rubamate. Of these, N, N'-dicinnamylidene 1, 6 hexamethylenediamine is preferred!

 [0046] As the polyol vulcanizing agent, a compound conventionally known as a fluororubber vulcanizing agent can be used. For example, a polyhydroxy compound, particularly, a polyhydroxy hydroxy compound having excellent heat resistance is also used. Aromatic compounds are preferably used.

 [0047] The polyhydroxy aromatic compound is not particularly limited. For example, 2, 2 bis (4 hydroxyphenol) propane (hereinafter referred to as bisphenol A), 2, 2 bis (4 hydroxyphenol). ) Perfluoropropane (hereinafter referred to as bisphenol AF), resorcin, 1,3 dihydroxybenzene, 1,7 dihydroxynaphthalene, 2,7 dihydroxynaphthalene, 1,6 dihydroxynaphthalene, 4,4'-dihydroxydiphenyl 4, 4 'dihydroxystilbene, 2, 6 dihydroxyanthracene, hydroquinone, catechol, 2, 2-bis (4-hydroxyphenol) butane (hereinafter referred to as bisphenol B), 4, 4-bis (4— Hydroxyphenol) Valeric acid, 2, 2 Bis (4 hydroxyphenol) Tetrafluorodiclopropane Propane, 4, 4, Dihydroxydiph Ninoles norephone, 4, 4, -dihydroxydiphenyl ketone, tri (4-hydroxyphenol) methane, 3, 3 ', 5, 5, monotetrachlorobisphenol A, 3, 3', 5, 5, One tetrabromobisphenol A. These polyhydroxy aromatic compounds may be alkali metal salts, alkaline earth metal salts, and the like, but it is preferable that the above metal salts are not used when the copolymer is prayed using an acid. ,.

 [0048] The peroxide vulcanizing agent may be a compound having a reaction activity with respect to a peroxide radical and a polymer radical. For example, CH = CH-, CH =

 twenty two

One example is a polyfunctional compound having a functional group such as CHCH and CF = CF. Concrete

twenty two

For example, triallyl cyanurate, triallyl isocyanurate (TAIC), triali norenore meranole, triarinore trimellitate, N, N '—n-phenylene bismaleimide, dipro Pagyl terephthalate, diallyl phthalate, tetraallyl terephthalate amide, triallyl phosphate, bismaleimide, fluorinated triallyl isocyanurate (1, 3, 5 tris (2, 3, 3, trifluoro 2-probe)) 1, 3, 5 卜 riadin— 2, 4, 6 卜 lion), tris (diallylamine) S triazine, triallyl phosphite, N, N diallyacrylamide, 1, 6 divinyldodecafluor hexane, Xaarylphosphoramide, N, N, N ', N' —tetraaryltetraphthalamide, N, N, N ′, N ′ —tetraarylmalonamide, tributylisocyanurate, 2,4, 6 Tribylmethyltrisiloxane, tri (5 norbornene-2-methylene) cyanurate, triallyl phosphite. Among these, triallyl isocyanurate (TAIC) is preferable from the viewpoint of vulcanizability and physical properties of the vulcanizate.

[0049] Among these vulcanizing agents, the resulting sealant has a small compression set, a good moldability, and an excellent sealing property, so that a polyhydroxy compound is a preferred heat resistance. Since bisphenol AF is more preferable, bisphenol AF is more preferable.

 [0050] The amount of the vulcanizing agent is 0.5 to 1.7 parts by weight and preferably 0.6 to 1.5 parts by weight with respect to 100 parts by weight of the fluororubber. More preferably, it is 0.7 to 1.3 parts by weight. If the vulcanizing agent is less than 0.5 parts by weight, the crosslinking density tends to be low and the compression set tends to be large, and if it exceeds 1.7 parts by weight, the crosslinking density becomes too high. Tend to break easily.

 [0051] In the polyol vulcanization system, a vulcanization accelerator is usually used in combination with the polyol vulcanizing agent. When a vulcanization accelerator is used, the vulcanization reaction can be promoted by promoting the formation of an intramolecular double bond in the dehydrofluorination reaction of the fluororubber main chain.

 [0052] As the vulcanization accelerator for the polyol vulcanization system, a compound having a property that it is difficult to add to the fluororubber main chain is preferred, and an organic compound is generally used. There is no particular limitation on the onium compound, and examples thereof include an ammonium compound such as a quaternary ammonium salt, a phosphonium compound such as a quaternary phosphonium salt, and an oxo-um. Compounds, sulfo-compounds, cyclic amines, monofunctional amine compounds, and the like. Among these, quaternary ammonium salts and quaternary phosphonium salts are preferred.

[0053] The quaternary ammonium salt is not particularly limited. For example, 8-methyl 1,8 dia Zabicyclo [5, 4, 0] —7 Undece-um chloride, 8-Methyl-1,8 Diazabicyclo [5, 4, 0] — 7 Undesse-um iodide, 8-Methyl-1,8 Diazabicyclo [5, 4, 0] — 7 Undesse-um hydroxide, 8-methyl-1,8 diazabicyclo [5,

4, 0] —7undecem methylsulfate, 8 ethyl 1,8 diazabicyclo [

5, 4, 0] — 7 Undecem-bromide, 8 Propyl 1, 8 Diazabicyclo [5, 4, 0] — 7 Undecem-bromide, 8 Dodecyl 1, 8 Diazabicyclo [5, 4, 0]-7 — Undece- Umchloride, 8 dodecyl 1,8 diazabicyclo [5, 4, 0] — 7 und dec-um hydroxide, 8 eicosyl— 1, 8 diazabicyclo [5, 4, 0]-7- undese-um chloride, 8—Tetracosyl 1,8 diazabicyclo [5, 4, 0] — 7 und dec-um chloride, 8 benzyl 1, 1, 8 diazabicyclo [5, 4, 0] — 7 und dec-um chloride (hereinafter referred to as DBU—B) ), 8 Benzyl 1 1,8 Diazabicyclo [5, 4, 0] 7 Undece-um Hydroxide, 8 Phenethyl- 1,8 Diazabicyclo [5, 4

, 0] —7 undecyl-um chloride, 8— (3 propyl) — 1,8 diazabisium [5, 4, 0] —7 undec-um chloride. Among these, DBU-B is preferable from the viewpoint of vulcanizability and physical properties of the vulcanizate.

[0054] The quaternary phospho-um salt is not particularly limited, and examples thereof include tetrabutyl phospho-um chloride, benzyl triphenyl phospho-um chloride (hereinafter referred to as BTPPC), benzyl trimethyl phospho-um chloride, Examples thereof include benzyltributylphosphomethylene chloride, tributylarylphosphonium chloride, tributyl-2-methoxypropylphosphonium chloride, and benzylphenol (dimethylamino) phosphonium chloride. Among these, vulcanizability and physical properties of vulcanizates In view of the above, benzyltriphenylphospho-muchloride (BTPPC) is preferred.

 [0055] Further, as a vulcanization accelerator, a quaternary ammonium salt, a solid solution of a quaternary phosphonium salt and bisphenol AF, chlorine-free disclosed in JP-A-11-147891 Vulcanization accelerators can also be used.

[0056] The peroxide vulcanization accelerator may be any organic peroxide compound that can easily generate a peroxide radical in the presence of heat or a redox system. Bis (t-butylperoxy) -3,5,5 trimethylcyclohexane, 2,5 dimethylhexyl Sun 2,5 dihydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, a, a bis (t-butylperoxy) p-diisopropylbenzene, 2,5 dimethyl-2,5 di (t-butylperoxy) Hexane, 2,5 dimethyl-2,5 di (t-butylperoxy) monohexine-3, benzoyl peroxide, t-butylperoxybenzene, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate, etc. Can give. Among these, 2,5 dimethyl-2,5 di (t-butylperoxy) hexane is preferable.

 [0057] The blending amount of the vulcanization accelerator is 0.1 to 2.0 parts by weight, preferably S, and more preferably 0.1 to 1.5 parts by weight with respect to 100 parts by weight of the fluororubber. More preferred is 1 to 0.7 parts by weight. If the blending amount of the vulcanization accelerator is less than 0.1 parts by weight, the vulcanization speed will be slow and the productivity tends to deteriorate, and if it exceeds 2.0 parts by weight, the vulcanization speed will be too fast. Scorch and molding defects tend to occur.

 [0058] A filler may be added to the rubber composition of the present invention. Any filler that is generally used for fluoro rubber can be used! ,.

 [0059] Examples of the filler include thermal black, furnace black, channel black, bituminous coal filler (mineral black), talc, white carbon, clay, magnesium oxide, calcium oxide, titanium oxide, silicon oxide, and oxide. Metal oxides such as aluminum, metal hydroxides such as magnesium hydroxide, aluminum hydroxide, calcium hydroxide, carbonates such as magnesium carbonate, aluminum carbonate, calcium carbonate, barium carbonate, magnesium silicate, calcium silicate Silicates such as sodium silicate and aluminum silicate, sulfates such as aluminum sulfate, calcium sulfate and barium sulfate, synthetic hydrotalcite, metal sulfides such as molybdenum disulfide, iron sulfide and copper sulfide, diatomaceous earth, asbestos, ritbon (Sulfur Lead Z barium sulfide), graphite, carbon black, carbon fluoride, calcium fluoride, Kotasu and the like.

[0060] The blending amount of the filler is usually 0 to L00 parts by weight, more preferably 0 to 50 parts by weight with respect to 100 parts by weight of the fluororubber, which varies depending on the type of filler. Filler strength S When the amount exceeds 100 parts by weight, the hardness increases, the workability deteriorates and the compression set tends to deteriorate. [0061] Further, in order to achieve both high sealing performance and high cracking performance, it is preferable to use a combination of bituminous coal filler and other fillers. In this case, the blending amount of the bituminous coal filler is preferably 5 to 30 parts by weight, more preferably 5 to 15 parts by weight with respect to 100 parts by weight of the fluororubber. If the blending amount of the bituminous coal filler is less than 5 parts by weight, the compression set tends to be poor, and if it exceeds 30 parts by weight, the hardness of the molded product tends to be hard and the sealing property tends to be poor. Even if the hardness is adjusted by the ratio with other fillers, if the bituminous coal filler exceeds 30 parts by weight, it is preferable because the mechanical strength is lowered and it is easy to break during compression.

 [0062] The rubber composition of the present invention may be added with a metal oxide or a metal hydroxide as an acid acceptor or a vulcanization acceleration aid.

 [0063] Metal oxides are mainly used as acid acceptors, and are used in polyol vulcanization systems and polyamine vulcanization systems to neutralize acidic substances generated during vulcanization.

 [0064] Metal hydroxides are mainly used as vulcanization accelerators, and in polyol vulcanization systems, react with calorific accelerators to activate dehydrofluorination and activate vulcanization accelerators. Thus, the vulcanization reaction can be promoted.

 [0065] Examples of the metal oxide include magnesium oxide, lead oxide, calcium oxide, zinc oxide, iron oxide, titanium oxide, silicon oxide, and aluminum oxide. Of these, magnesium oxide and its surface-treated product are preferred as acid acceptors. In addition to this, synthetic acid and id mouth talcite can also be used as the acid acceptor. In addition, zinc oxide is used for improving heat resistance, iron oxide, titanium oxide, and silicon oxide are used as colorants and fillers, and aluminum oxide is used as a thermal conductivity imparting agent.

 [0066] Examples of the metal hydroxide include calcium hydroxide, magnesium hydroxide, aluminum hydroxide and the like. Among these, calcium hydroxide and its surface-treated product are preferable.

[0067] The addition amount of the metal oxide and the metal hydroxide is preferably 0 to 25 parts by weight, preferably 0 to 10 parts by weight, with respect to 100 parts by weight of the fluororubber. More preferred. If the amount of metal oxide exceeds 25 parts by weight, scorching tends to occur, and if the amount of metal hydroxide exceeds 25 parts by weight, compression set tends to deteriorate. [0068] Further, in the rubber composition of the present invention, a processing aid, a release agent, a colorant, a conductivity imparting agent, a thermal conductivity imparting agent, a surface non-sticking agent, as long as the effects of the present invention are not impaired. Compounding agents such as pressure-sensitive adhesives, adhesives' pressure-sensitive adhesives, flexibility-imparting agents, heat resistance improvers and flame retardants may be added.

 [0069] The rubber composition of the present invention generally uses a fluororubber, a vulcanizing agent, and, if necessary, a vulcanization accelerator, a filler, a metal oxide, a metal hydroxide, and other compounding agents. It can be obtained by kneading using a rubber kneading apparatus. As the rubber kneading apparatus, a roll, a kneader, a Banbury mixer, an internal mixer, a twin screw extruder, or the like can be used.

 [0070] Vulcanizing agents, vulcanization accelerators, fillers, metal oxides, metal hydroxides, and other compounding agents must be uniformly dispersed in the rubber. It tends to cause a decrease in speed, a decrease in mechanical strength, a decrease in elongation, and a poor cracking property during compression.

 [0071] In particular, when a polyhydroxy compound is used as a vulcanizing agent, the melting point of the vulcanizing agent 'vulcanization accelerator is often relatively high. Sulfur agent 'vulcanization accelerator-kneaded while melted at a high temperature of 120 to 200 ° C using a closed kneading device such as a jar, and then filled with filler, metal oxide, metal hydroxide A method of kneading a product or other compounding agent at a relatively low temperature below this is preferable. There is also a method of uniformly dispersing using a solid solution in which a vulcanizing agent and a vulcanization accelerator are melted and a melting point is lowered.

 [0072] Further, after kneading the fluororubber, vulcanizing agent, vulcanization accelerator, filler, metal oxide, metal hydroxide, and other compounding agents, the mixture is allowed to stand at room temperature for 12 hours or more and then kneaded again. By doing so, dispersibility can be further improved.

 [0073] The sealing material of the present invention is obtained by vulcanization molding of the rubber composition of the present invention using a general rubber molding machine. As the rubber molding machine, a compression press, an injection molding machine, an injection molding machine or the like can be used. A rubber composition preformed into a predetermined shape using a roll, an extruder, or a pre-molding machine is used. Perform primary vulcanization by heating at ° C for about 1 to 60 minutes. The method using a compression press is a molding method suitable for fluoro rubber having a higher viscosity than that of other methods, and is preferably used as a method for molding the sealing material of the present invention.

[0074] The sealing material formed by the primary vulcanization is subjected to secondary vulcanization using an air oven. It is desirable. The secondary vulcanization is performed for the purpose of completing the above primary vulcanization reaction, decomposing the vulcanizing agent / vulcanization accelerator remaining without cross-linking reaction, and releasing the gas generated during vulcanization. By performing secondary vulcanization, the mechanical properties such as tensile strength and compression set of the sealing material of the present invention can be improved.

 [0075] The secondary vulcanization conditions usually vary depending on the vulcanization system. The polyamine vulcanization system is 180-220 ° C for about 16-24 hours, and the polyol vulcanization system is 210-260 ° C for about 16-24 hours. The peroxide vulcanization system is generally performed at 160 to 200 ° C for about 2 to 24 hours. In the case of the sealing material of the present invention, the sealing property and cracking property at high temperature and high compression are characteristic, and secondary vulcanization at higher temperature is preferable. In the case of the sealing material of the present invention, it is preferable to carry out secondary vulcanization at a temperature of 280 ° C or higher for 1 hour or longer. At a temperature of 250 ° C or higher, 3 hours or longer, and then at a temperature of 290 ° C or higher. It is more preferable to perform secondary vulcanization for more than an hour. If the secondary vulcanization temperature is low, the compression set is insufficient due to the effect of the residual vulcanizing agent at high temperature and the vulcanization accelerator, and if the secondary vulcanization temperature is too high, the polymer deteriorates.

 [0076] The compounding amount of the vulcanizing agent with respect to 100 parts by weight of the fluororubber in the rubber composition of the present invention is X (parts by weight), 25% compression of 24-24'Ο ring, 280 ° CX compression at 72 hours It is preferable to satisfy 20% + Υ≤70 when the permanent strain is Y (%). It is more preferable to satisfy 20% + Υ≤68, more preferably 20% + Υ≤68. Also, the lower limit of 20Χ + Υ is not particularly limited, but it is preferable to satisfy 1≤20Χ + Υ. It is more preferable to satisfy 30≤ 2ΟΧ + Υ. If 20Χ + Υ exceeds 70, even if the amount of vulcanizing agent is adjusted, it tends to be difficult to achieve both compression set and crackability.

 [0077] Also, 25% compression of 24-24 'ring made by vulcanization molding of the rubber composition of the present invention, compression set at 280 ° CX for 72 hours is Y (%), and 50% compression of the same ring 280 ° CX When the crack rate at 1 hour is Z (%), it is preferable to satisfy 10Y + Z≤500. 10 0 + Υ≤480 is more preferable. It is even better to meet. Further, the lower limit value of 10Y + Z is not particularly limited, but it is preferable to satisfy 100≤10Υ + Ζ. If 10Y + Z exceeds 500, it tends to be difficult to achieve both compression set and crackability.

[0078] The sealing material of the present invention has a sealing property and a cracking property under high temperature and high compression as described above. Therefore, it is possible to apply pressure such as caulking for the purpose of ensuring the sealing performance, and it can be suitably used for applications that require the sealing performance to be maintained for long periods of use at high temperatures.

 [0079] Further, the present invention relates to a sealing material for an oxygen sensor obtained by vulcanizing a rubber composition comprising a fluororubber and a vulcanizing agent. ML1 + 20, 140 ° C) relates to an oxygen sensor sealing material having a temperature of 70 to 150.

 [0080] As the fluororubber and the vulcanizing agent, those described above can be preferably used. Further, the Mooney viscosity of the fluoro rubber, the measuring method of Mooney viscosity, the vulcanization conditions, and the like are the same as described above.

 [0081] The blending amount of the vulcanizing agent is not particularly limited, but the above blending amount can be employed.

 [0082] The use of the sealing material of the present invention is not particularly limited. For example, an engine body of a car engine, a main motion system, a valve system, a lubricant / cooling system, a fuel system, an intake / exhaust system; Transmission system; Chassis steering system; Brake system; Heat-resistant, oil-resistant, fuel oil-resistant, anti-freezing liquid resistance for engine cooling, steam-resistant, such as basic electrical parts of control equipment, control system electrical parts, electrical equipment parts Sealing materials such as gaskets that require high performance and non-contact type and contact type packings (self-seal packing, piston ring, split ring type packing, mechanical seal, oil seal, etc.).

[0083] The sealing material used in the engine body of the automobile engine is not particularly limited. For example, gaskets such as cylinder head gasket, cylinder head cover gasket, oil pan packing, general gasket, O-ring, packing, timing Examples include sealing materials such as belt cover gaskets.

[0084] The seal material used in the main motion system of the automobile engine is not particularly limited, and examples thereof include a shaft seal such as a crankshaft seal and a camshaft seal.

 [0085] The seal material used in the valve train of an automobile engine is not particularly limited, and examples thereof include a valve stem oil seal of an engine valve.

[0086] The lubricant used for the automotive engine's cooling system is particularly limited. For example, a seal gasket for an engine oil cooler can be mentioned.

 [0087] The seal material used in the engine fuel system for automobiles is not particularly limited. For example, a fuel pump connector, a fuel tank filler seal, a tank knocker, etc., a fuel tube connector O-link Injector / cushion ring of fuel injector, injector seal ring, injector O-ring, etc.

 [0088] The sealing material used for the intake and exhaust system of the automobile engine is not particularly limited. For example, the intake manifold seal packing of the hold, the exhaust hold packing, and the throttle throttle Examples include body packing and turbocharged turbine shaft seals.

 [0089] The seal material used in the transmission system of the automobile engine is not particularly limited. For example, a transmission-related bearing seal, an oil seal, an O-ring, a knock, etc., an O-ring of an automatic transmission. , Knockins and the like.

 [0090] The seal material used in the brake system of the automobile engine is not particularly limited. For example, a seal such as an oilless nole, an O-ring, a knocker, a piston cup (rubber cup) of a master cylinder, etc. Parseal, boots, etc.

 [0091] The seal material used in the electrical equipment for the automobile engine is not particularly limited, and examples thereof include an O-ring and a packing of a car air conditioner.

 [0092] Among these, the sealing material of the present invention is particularly suitable for an oxygen sensor, and further suitable for an automotive oxygen sensor.

[0093] Applications other than those for automobiles are not particularly limited. For example, oil-resistant, chemical-resistant, heat-resistant, steam-resistant or weather-resistant knocks, O-rings, and other sealing materials in shipping engines such as ships and aircraft. ; Similar packing, o-rings and seals in engineering plants; Similar packing, o-rings and seals in food plant equipment and food equipment (including household items); Similar packings and o-rings in nuclear plant equipment; Seal materials; similar packing, O-rings, seal materials, etc. for general engineering parts. Example

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

[0095] <Various viscosity>

 The obtained fluororubber is sheeted by passing it through a kneading roll machine (roll gap: approx. Using an L-shaped rotor, the measurement was conducted at 140 ° C with a preheating time of 1 minute and a measurement time of 20 minutes in accordance with JIS K 6300 (1994).

[0096] <Weight average molecular weight (Mw) and number average molecular weight (Mn)>

 Equipment: HLC-8020 (manufactured by Tosohichi Corporation)

 Column: 2 GPC KF-806M (Showa Column)

 GPC KF— 801 (manufactured by Showa Column) 1

 1 GPC KF—802 (Showa Column)

 Detector: RI detector (manufactured by Tosoichi Co., Ltd.)

 Developing solvent: Tetrahydrofuran

 Column temperature: 40 ° C

 Calibration curve temperature: 35 ° C

 Sample concentration: 0.1% by weight

 Standard sample: Various monodisperse polystyrene ((Mw / Mn) = 1. 14 (Max)), TSK standa rd POLYSTYRENE (manufactured by Tosoichi Co., Ltd.)

[0097] Composition analysis>

¹⁹ F-NMR (Bruker AC300P type) was used for measurement. However, the TFE-containing polymer was measured using ¹⁹ F-NMR (FX100 model manufactured by JEOL Ltd.).

[0098] <Hardness>

 Using the vulcanized sheets obtained in Examples and Comparative Examples, measurement was performed according to JIS K6253 (1997) using a type A durometer (trade name: ASKER, manufactured by Kobunshi Keiki Co., Ltd.).

[0099] <Tensile breaking strength and tensile breaking elongation> Using the vulcanized sheets obtained in Examples and Comparative Examples, using a tensile tester (Tensilon, manufactured by Orientec Co., Ltd.), according to JIS K6251 (1993), under the condition of 500 mmZ, Using Dumbbell No. 4, the tensile strength at break and elongation at 23 ° C were measured.

[0100] <Compression set>

 According to ASTM D1313 (1994), the P-24 · O rings obtained in the examples and comparative examples were allowed to stand for 72 hours at a temperature of 280 ° C and a compression deformation of 25% for 72 hours. Strain was measured.

[0101] <Crack ratio>

 The P-24 · O-rings obtained in the examples and comparative examples were charged into a compression device and a spacer preheated to 280 ° C, and the compression rate was 50%, 280 ° C for 1 hour. After holding, it was taken out from the compression device and visually checked for cracks. A total of 10 O-links were examined, and the crack rate was calculated from the following formula.

 Cracking rate (%) = [(Number of broken O-rings) Ζΐο] χ ιοο

[0102] The trade names in the table and specification are as follows.

 BIS-AF: Bisphenol AF

 P-21: Solid solution in which bisphenol AF and BTPPC are mixed at a weight ratio of 2: 1, melted at 180 ° C for 1-2 hours, and cooled and crushed

 N—990: Thermal black from Cancarb

 325—BA: Bituminous coal filler from Key stone Filler & Mfg

 MA-150: Highly active acid magnesium from Kyowa Chemical Industry Co., Ltd.

 CALDIC2000: Calcium hydroxide manufactured by Omi Chemical Co., Ltd.

[0103] Production Example 1 (Production of seed polymer)

As stirrer, the polymerization vessel having an internal volume of 1.8 liters with an electromagnetic induction stirrer, pure water 720 g, 10 weight _^0/0 par full O b octanoic acid ammonium - © anhydrous solution 290 g, and Jechiru malonate 0. 6 g was charged and the inside of the system was sufficiently replaced with nitrogen gas, and then the pressure was reduced. This operation was repeated three times, and VdF20g and HFP51g were charged under reduced pressure, and the temperature was raised to 80 ° C with stirring. Next, persulfate ammonium salt (APS) O. 02g dissolved in pure water 0.6g was added to nitrogen. Polymerization was started by press-fitting with gas. The polymerization pressure was set to 2 MPa, and VdFZHFP mixed monomer (78Z22 (mol%)) was continuously fed to carry out the polymerization with stirring in order to compensate for the pressure drop during the polymerization. By the end of the polymerization, 215 g of monomer was fed into the tank.

[0104] The resulting weight of the emulsion 1233G, the polymer concentration is 1 wt% 18. The number of polymer particles child got emulsion of 1. 2 X 10 ¹⁶ cells / water lg. After 30 minutes, the stirring was stopped, and the polymerization was stopped by releasing the monomer.

 [0105] Production Example 2 (Production of binary fluororubber (BP-1))

 Production Example 1 Internal volume with the same electromagnetic induction stirrer 1. Charge a water tank of 83 liters with 977 g of pure water and 10.2 g of an aqueous dispersion of polymer particles produced in Production Example 1, and nitrogen gas in the system Then, the pressure was reduced. This operation was repeated three times. Under reduced pressure, 142 g of VdF and 449 g of HFP were charged, and the temperature was raised to 80 ° C. with stirring. Next, APSO.08g dissolved in 1.45g of methyl malonate and 15g of pure water was injected with nitrogen gas to start the polymerization, and the polymerization was continued under the conditions of (a) and (b). Stirring was stopped and the monomer was released to stop the polymerization.

 (a) VdFZHFP (78/22 (mol%)) The monomer mixture was continuously fed, and the pressure in the gas phase part was maintained at 6 MPa. By the end of the polymerization, 282 g of monomer was fed into the tank.

 (b) The stirring speed was maintained at 560 rpm.

[0106] The weight of the obtained emulsion was 1376 g, and the polymer concentration was 26.4 wt%. The fluororubber was 363 g, the weight average molecular weight Mw measured by GPC was 510,000, the number average molecular weight Mn was 210,000, and MwZMn was 2.4. Further, the composition of the ¹⁹ F- was determined by NMR the polymer was (1 711? = 78722 (Monore _^0/0).

 [0107] Production Example 3 (Production of binary fluororubber (BP-2))

 Fluoro rubber was polymerized in the same manner as in Production Example 2, except that 1.80 g of methyl malonate and 0.09 g of APS were used.

[0108] The polymerization time is 2.7 hours, the weight of the obtained emulsion 1380 g, the polymer concentration was 26.7 by weight _^0/0. The fluororubber was 368 g, the weight average molecular weight Mw measured by GPC was 460,000, the number average molecular weight Mn was 200,000, and MwZMn was 2.3. ¹⁹ F - composition of the polymer determined by NMR was VdFZHFP = 78Z22 (mol ^_0/0).

[0109] Production Example 4 (Production of binary fluororubber (BP-3))

 Fluorine rubber was polymerized in the same manner as in Production Example 2 except that 2.0 g of jetty malonate and 0.09 g of APS were used.

[0110] The polymerization time is 2.9 hours, the weight of the obtained emulsion 1372 g, the polymer concentration 26. was 4 by weight _^0/0. The fluororubber was 362 g, the weight average molecular weight Mw measured by GPC was 400,000, the number average molecular weight Mn was 170,000, and MwZMn was 2.4. ¹⁹ F

- composition of the polymer determined by NMR was VdFZHFP = 78Z22 (mol ^_0/0).

[0111] Production Example 5 (Production of binary fluororubber (BP-4))

 Fluorine rubber was polymerized in the same manner as in Production Example 2 except that 280 g of decyl malonate and 0.12 g of APS were used.

[0112] The polymerization time was 2.5 hours, the weight of the obtained emulsion was 1364 g, and the polymer concentration was 26.5% by weight. The fluororubber was 361 g, the weight average molecular weight Mw measured by GPC was 290,000, the number average molecular weight Mn was 130,000, and MwZMn was 2.2. ¹⁹ F

- composition of the polymer determined by NMR was VdFZHFP = 78Z22 (mol ^_0/0).

[0113] Production Example 6 (Production of ternary fluororubber (BP-5))

 In a 48 liter stainless steel autoclave with no ignition source, put 29 liters of pure water and 29 g of C F COONH as a milky powder, and thoroughly replace the system with nitrogen gas.

 7 15 4

After that, the temperature inside the system was raised to 60 ° C. While stirring at 200 rpm, a gas mixture of VdF and HFP and TFE, were charged as pressure in VdFZHFPZTFE = 56Z28Zl6 (mol _^0/0) is 15k gf / cm ² G.

[0114] Subsequently, a solution in which 24 g of ammonium persulfate was dissolved in 50 mL of water was injected with nitrogen to initiate the reaction.

[0115] Since the pressure drop with the progress of the polymerization reaction, VdF, a mixed gas of HFP and TFE, VdFZHFPZTFE = 66. 5/16/17. 5 ( mol _^0/0) as internal pressure 15kgfZc m ² G At the same time, isopentane as a chain transfer agent was equally divided into 5 parts with respect to the reaction yield, and a total amount of 2.5 cm ^{3 was} charged. After 326 minutes from the start, the supply is stopped, the autoclave is cooled, the unreacted monomer is released, and the solid content concentration is 20 to 25% by mass. A clear aqueous dispersion was obtained. The resulting aqueous dispersion was Koino by a conventional method, washed dried poly mer obtained by Koino, give VdFZTFEZHFP = 65Z20Zl5 (mol _^0/0) is ternary off Tsu-containing elastomer one white solid It was.

[0116] The polymerization average molecular weight was measured by the method described above, and it was 550,000. Furthermore, ¹⁹ FN composition of the measured polymer in the MR VdFZTFEZHFP = 65Z20Zl5 (mol _^0/0) der ivy o

 Example 1 (Production of Binary Fluororubber Composition)

 While heating the pressure-type one-liter jacket with a volume of 3 liters with a heater to 140 ° C, gradually add 4000 g of the binary fluororubber obtained in Production Example 2, followed by BIS- AF 26 g, 26 g of P-21 was added and kneaded for 12 minutes. Each time kneading for 3 minutes, the rotor was stopped, the pressure lid was released, the top and bottom of the rubber were switched by reverse rotation of the rotor, and the kneading was repeated again. The rubber temperature immediately after kneading was 168 ° C. The number of rotations of the rotor was 33 rpm for the front blade and 22 rpm for the rear blade.

 [0118] The kneaded rubber is cooled and finally sheeted by using a kneading roll machine equipped with two 12 inch diameter rolls, and consists of fluoro rubber, vulcanizing agent and vulcanization accelerator. The composition (S-1) was taken out.

 [0119] Composition (S-1), thermal black (N-990 Cancarb), bituminous coal filler (32 5BA Keystone Filler & Mfg), highly active magnesium oxide (MA-150, manufactured by Kyowa Chemical Industry Co., Ltd.) ), Calcium hydroxide (CALDIC2000 manufactured by Omi Chemical Co., Ltd.) was added so as to have the mixing ratio shown in Table 2, and using a kneading roll machine equipped with two 8-inch rolls in a normal manner, It knead | mixed at 25-70 degreeC. This was left at room temperature for about 20 hours and then kneaded again in the same kneader, finally sheeted to a thickness of about 2 mm, and unvulcanized rubber HG-1) was taken out.

[0120] Next, the unvulcanized rubber sheet (G-1) was subjected to primary vulcanization with a 100-ton compression press at a gauge pressure of 60kgfZcm ² at 170 ° C for 10 minutes to obtain a vulcanized sheet (width: about 140mm, Length: approx. 110mm, thickness: approx. 2mm) and a Ρ-24 'ring (inner diameter: 23.7mm, thickness 3.5mm, exercise O-ring) were molded. Further, the obtained vulcanized sheet and P-24 · 0 ring were subjected to secondary vulcanization at 260 ° C for 5 hours and at 300 ° C for 2 hours. [0121] Examples 2 to 4 and Comparative Examples 1 to 3

 A vulcanized sheet and a P-24 · O ring were obtained in the same manner as in Example 1 except that the fluororubbers obtained in Production Examples 2 to 6 were used and the blending conditions shown in Table 2 were used.

 [0122] In Table 2, X is the compounding amount (parts by weight) of the vulcanizing agent with respect to 100 parts by weight of fluororubber, Y is 25% compression of P-24 · O ring, 280 ° CX compression at 72 hours Permanent strain (%) and Z is the crack rate (%) at 50% compression, 280 ° CX for 1 hour of P-24 · 0 ring.

[0123] [Table 1] Table 1

 The rubber was not collected and measurement was not possible.

[0124] [Table 2]

Table 2

Industrial applicability

The rubber composition of the present invention is a rubber composition comprising a fluoro rubber and a vulcanizing agent, and the vulcanizing agent is 0.5 to 1.7 parts by weight with respect to 100 parts by weight of the fluoro rubber in the composition. In addition, the Mooney viscosity (MLl + 20, 140 ° C) of the fluororubber in the composition is 70 to 150, so that the sealing material obtained by vulcanization molding has high temperature sealing properties. In addition to imparting crackability, the rubber composition also has good processability. Furthermore, the sealing material comprising the rubber composition of the present invention is one that retains its sealing performance when used for a long time at high temperatures.

ll8T0 / S00Zdf / X3d SS OAV

Claims

 The scope of the claims

 [I] A rubber composition having fluororubber and vulcanizing power,

 The vulcanizing agent is 0.5 to 1.7 parts by weight with respect to 100 parts by weight of the fluororubber in the composition, and the mu-one viscosity (ML1 + 20, 140) of the fluororubber in the composition. ° C) A rubber composition with a force ^ 0-150.

 [2] The rubber composition according to [1], which has a Mu-one viscosity (ML1 + 20, 140 ° C) force of fluororubber of 100 to 150.

[3] The rubber composition according to [1] or [2], wherein the fluororubber is a fluororubber containing a biridene fluoride unit.

[4] The rubber composition according to any one of [1] to [3] above, wherein the fluororubber is a binary fluororubber having a biridene fluoride unit and a hexafluoropropylene unit force.

[5] X (parts by weight) of vulcanizing agent with respect to 100 parts by weight of fluororubber, 25% compression of P-24 · 0 ring, and compression set at 280 ° CX for 72 hours as Υ (%) The rubber composition according to any one of claims 1 to 4, which sometimes satisfies 20Χ + Υ≤70.

 [6] The rubber or ancestor according to any one of claims 1 to 5, wherein the vulcanizing agent is a polyhydroxy compound.

 [7] The rubber composition according to any one of [1] to [6], which contains 5 to 30 parts by weight of a bituminous coal filler with respect to 100 parts by weight of the fluororubber.

[8] A seal material obtained by vulcanizing the rubber composition according to any one of claims 1 to 7.

 [9] The sealing material according to claim 8, which is heat-treated at a temperature of 280 ° C or higher for 1 hour or longer after vulcanization molding.

 [10] 25% compression of 24-24'Ο ring, compression set at 280 ° CX for 72 hours is Υ (%), and 50% compression of Ο-ring is 280 ° CX for 1 hour. ), The sealing material according to claim 8 or 9, wherein 10 0 + Υ≤500 is satisfied.

[II] A sealing material for an oxygen sensor that also serves as the sealing material according to any one of claims 8 to 10. A sealing material for an oxygen sensor obtained by vulcanizing a rubber composition having a fluororubber and a vulcanizing power,

A sealing material for an oxygen sensor, wherein the fluororubber in the composition has a mu-one viscosity (ML1 + 20, 140 ° C) of 70 to 150.