JP6435666B2 - Fluoro rubber composition - Google Patents

Description

  The present invention relates to a fluororubber composition. More specifically, the present invention relates to a fluororubber composition used as a molding material such as an oil seal.

  Fluororubber has excellent oil resistance and fuel oil resistance, so it is used as a sealing material for O-rings, packing, etc. in a wide range of fields such as automobiles and industrial machines. For example, oil seals are used in automobiles, industrial machines, etc. It is widely used as an important machine part in the field.

  The present applicant has previously proposed a rubber composition containing 1 to 100 parts by weight of an acicular or fibrous filler having an aspect ratio of 8 or more per 100 parts by weight of rubber as a sealing material. Discloses a fluororubber composition in which wollastonite having an aspect ratio of 8 is blended with a vinylidene fluoride (VdF) -hexafluoropropylene (HFP) binary copolymer rubber (Patent Document 1). Further, a fluororubber composition using a vinylidene fluoride (VdF) -hexafluoropropylene (HFP) -tetrafluoroethylene (TFE) terpolymer rubber is also generally used as a sealing material.

  However, fluororubbers vulcanized and molded from these binary or ternary fluororubber compositions are not sufficient in terms of resistance to basic additives contained in lubricating oils. There is a need for improvement in applications where a large amount of lubricating oil is to be sealed. In recent years, there has been a demand for longer life of equipment, and if a fluororubber composition with excellent durability such as heat resistance and wear resistance can be applied to sealing applications containing a large amount of additives such as gear oil, the length of the equipment will be increased. It is possible to contribute to life extension.

JP 2008-64201 A Japanese Patent No. 4,491,547

  The object of the present invention is suitably used as a molding material for a seal such as an oil seal, which has excellent durability such as heat resistance and wear resistance, and can sufficiently satisfy lubricating oil resistance and sealability. The object is to provide a fluororubber composition.

The object of the present invention is to provide diatomaceous earth having an average particle diameter of 6 to 35 μm per 100 parts by weight of fluororubber comprising a quinarypolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-ethylene-perfluoro (alkyl vinyl ether). , A fluororubber composition containing 3 to 60 parts by weight of at least one of wollastonite, talc, graphite and carbon fiber.

  In addition to vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, perfluoro (alkyl vinyl ether) as a fluororubber copolymerization monomer, the fluororubber composition according to the present invention functions as a protective polymer against attack by a base in the polymer main chain. Because of the introduction of ethylene, improved base resistance compared to binary or ternary copolymer fluororubbers that do not use ethylene as a comonomer while maintaining the properties of fluororubber It has an excellent effect of being able to significantly suppress deterioration due to caking.

  Fluoro rubber includes vinylidene fluoride [VdF] -hexafluoropropylene [HFP] -tetrafluoroethylene [TFE] -ethylene [E] -perfluoro (alkyl vinyl ether) [FAVE] terpolymer, preferably VdF- HFP-TFE-E-perfluoro (methyl vinyl ether) [FMVE] terpolymer is used. For example, commercially available Solvey product Thecnoflon BR9151 can be used as it is. Here, in the case of using a fluororubber that is not copolymerized with ethylene, the sealing material that is a vulcanized molded product cannot achieve the durability intended by the present invention. Such a ternary copolymer is preferably crosslinked by a crosslinking system comprising an organic peroxide crosslinking agent-polyfunctional unsaturated compound co-crosslinking agent.

Fluororubber contains diatomite, wollastonite (CaO · SiO ₂ ), talc (Mg ₃ Si ₃ O ₁₀ (OH) ₂ ), graphite, having an average particle size (measured by laser scattering method) of 6 to 35 μm as fillers. , At least one of mica and carbon fiber, preferably diatomaceous earth, wollastonite, talc, graphite and carbon fiber are blended in an amount of 1 to 60 parts by weight, preferably 3 to 50 parts by weight per 100 parts by weight of fluororubber . If the amount of these fillers is used in a smaller proportion, this vulcanized molded product cannot achieve the sealing performance intended by the present invention, whereas if it is used in a proportion higher than this, the composition Becomes too hard, which adversely affects moldability. Here, when the filler is fibrous, the average particle diameter means the average fiber length.

  Patent Document 1 discloses a wollastonite 1 to 100 having an aspect ratio of 8 or more per 100 parts by weight of fluororubber (VdF-HFP copolymer) as a molding material for forward and reverse rotation oil seals for railway vehicles. Although a fluororubber composition prepared by adding parts by weight and kneading them is disclosed, there is no teaching about the ternary copolymer used in the present invention. When the binary copolymer disclosed in this document or the ternary copolymer generally used as a sealing material is used, diatomaceous earth, wollastonite, talc, graphite, having an average fiber diameter of 6 μm or more, Even when at least one of mica and carbon fiber is used, it is difficult to achieve a durability time of, for example, 200 hours or more as shown in Comparative Examples 2 to 3 below.

In Patent Document 2, vinylidene fluoride, tetrafluoroethylene, perfluoro (methyl vinyl ether), CF ₂ = CFO [CF ₂ CF (CF ₃ ) O] nCF ₃ and RfX (Rf is a non-carbon having 2 to 8 carbon atoms). There is disclosed a fluorine-containing elastomer having a copolymer component as a saturated fluorohydrocarbon group, which may have one or more ether bonds in the group, and X is bromine or iodine. However, in this case as well, as in the binary copolymer fluororubber or ternary copolymer fluororubber described in Patent Document 1, for example, a VdF-HFP bond is blocked by a basic additive contained in a lubricating oil or the like. The elimination reaction of hydride occurs and a C = C double bond is generated, and an amine is added to this double bond, resulting in curing deterioration. On the other hand, in the present invention, by selecting a fluororubber using ethylene as a copolymerization component, the VdF content of the polymer main chain or the VdF-HFP bond is reduced, thereby improving the base resistance and curing deterioration. Is significantly different from the known fluororubber composition in that it is possible to remarkably suppress the above.

  To the fluororubber composition comprising the above essential components, various compounding agents required for vulcanization operation, physical properties, and functions are added. For example, polyol-based or organic peroxide used for fluororubber vulcanization -Based vulcanizing agents, vulcanizing aids such as quaternary onium salts, polyfunctional unsaturated compound co-crosslinking agents, reinforcing agents or fillers other than essential components such as carbon black, divalent metal oxides, hydroxides Alternatively, an acid acceptor such as hydrotalcite and other necessary compounding agents are blended, and then the composition is prepared by any kneading means using an open roll, a kneader, and the like, and about 160 to 200 ° C., about 3 It is vulcanized and formed into a sealing material such as an oil seal by performing a heat press for ˜30 minutes and optionally performing secondary vulcanization at about 150 to 250 ° C. for about 0.5 to 24 hours.

  Next, the present invention will be described with reference to examples.

Example 1
Fluoro rubber (VdF-HFP-TFE-E-FMVE ternary copolymer: 100 parts by weight
Solvey product Tecnoflon BR9151)
Diatomaceous earth (central silica product silica 6B; average particle size 6.4μm) 30 〃
N990 carbon black 5 〃
Triallyl isocyanurate (Nippon Kasei products TAIC) 2 〃
Organic peroxides (NIPPON YILLOW PRODUCT PERHEXA 25B-40) 2 〃
The above components are kneaded using a kneader and an open roll, subjected to primary vulcanization at 180 ° C for 10 minutes and secondary vulcanization at 200 ° C for 24 hours, and an oil seal with an inner diameter of 85 mm, an outer diameter of 105 mm, and a width of 13 mm Was vulcanized and molded.

Example 2
In Example 1, the same amount (30 parts by weight) of wollastonite (NYCO Minerals product NYAD400; average fiber diameter 7 μm, average fiber length 35 μm, aspect ratio 5) was used instead of diatomaceous earth.

Example 3
In Example 1, the same amount (30 parts by weight) of talc (Asada Milled Product Talc SW-H; average particle size 14 μm) was used instead of diatomaceous earth.

Example 4
In Example 1, the same amount (30 parts by weight) of graphite (Japanese graphite product CPB6S; average particle size of 12 μm) was used instead of diatomaceous earth.

Example 5
In Example 1, 20 parts by weight of carbon fiber (Osaka Gas Chemical Product DonaCarbo S2404N; average fiber diameter 13 μm) was used instead of diatomaceous earth.

Comparative Example 1
In Example 1, diatomaceous earth was not used, and the amount of N990 carbon black was changed to 35 parts by weight.

Comparative Example 2
In Example 1, the same amount (100 parts by weight) of VdF-HFP binary copolymer (Daikin product DAIEL G-801) was used as the fluororubber.

Comparative Example 3
In Example 1, the same amount (100 parts by weight) of VdF-HFP-TFE terpolymer (Daikin product DAIEL G-9074) was used as the fluororubber.

Using the oil seals obtained in each of the above Examples and Comparative Examples, normal property measurements, immersion tests, and oil seal sealing tests were performed.
Normal state physical properties (hardness Hs): Conforms to JIS K6253: 1997, using type A durometer
Instantaneous hardness measured by immersion test: 150 ° C in industrial gear oil (Royal Purple Product Gear Premium 320)
The elongation before and after immersion for 140 hours was measured and the rate of change was calculated.
Also, bend the specimen after immersion at an angle of 180 ° to
No crack was observed, ○, crack was observed
Oil seal sealing test: An oil seal was set on a rotating test machine and industrial gear oil (G
Yer Premium 320) is sealed around the rotation axis,
Conditions of test temperature 130 ℃, rotation speed 6000rpm (circumferential speed 26.7m / sec)
Ran for 200 hours and checked for oil leaks
If there is no oil leak, it can be said that the sealing effect is clear.

The results obtained in the above examples and comparative examples are shown in the following table.
table
Example comparison example
Measurement / evaluation items 1 2 3 4 5 1 2 3
[Normal properties]
Hardness (Durometer A) 75 75 75 77 75 77 78 81
[Immersion test]
Rate of change in elongation (%) -31 -32 -29 -28 -30 -28 -96 -79
After bending 180 ° ○ ○ ○ ○ ○ ○ × ×
[Oil seal sealing test]
Oil leak No No No No No Yes Yes Yes

Claims (4)

Diatomaceous earth, wollastonite, talc having an average particle size of 6 to 35 μm per 100 parts by weight of fluororubber consisting of quinarypolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-ethylene-perfluoro (alkyl vinyl ether), A fluororubber composition containing 3 to 60 parts by weight of at least one of graphite, mica and carbon fiber.

  The fluororubber composition according to claim 1, wherein the fluororubber comprises a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-ethylene-perfluoro (methyl vinyl ether) ternary copolymer.   A sealing material vulcanized and molded from the fluororubber composition according to claim 1. The sealing material according to claim 3, which is used as an oil seal.