WO2013111643A1 - 自動車用オイルシール - Google Patents
自動車用オイルシール Download PDFInfo
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- WO2013111643A1 WO2013111643A1 PCT/JP2013/050632 JP2013050632W WO2013111643A1 WO 2013111643 A1 WO2013111643 A1 WO 2013111643A1 JP 2013050632 W JP2013050632 W JP 2013050632W WO 2013111643 A1 WO2013111643 A1 WO 2013111643A1
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- WIPO (PCT)
- Prior art keywords
- oil seal
- fluororesin
- seal
- automobiles
- lip portion
- Prior art date
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/32—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings
- F16J15/3204—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings with at least one lip
- F16J15/3208—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings with at least one lip provided with tension elements, e.g. elastic rings
- F16J15/3212—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings with at least one lip provided with tension elements, e.g. elastic rings with metal springs
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/32—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings
- F16J15/3204—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings with at least one lip
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/16—Sealings between relatively-moving surfaces
- F16J15/32—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings
- F16J15/3284—Sealings between relatively-moving surfaces with elastic sealings, e.g. O-rings characterised by their structure; Selection of materials
Definitions
- the present invention relates to an oil seal for automobiles.
- oil seals are used to prevent fluids such as engine oil from leaking.
- Examples of the oil seal for an automobile include an engine oil seal used in contact with an engine crankshaft, an oil seal used for a transmission, a valve stem seal used for a valve stem, and the like.
- Patent Document 1 As an oil seal for automobiles, for example, in Patent Document 1, as an engine oil seal, acrylic rubber (ACM), fluorine rubber (FKM), nitrile rubber (NBR), urethane rubber (U), silicone rubber, hydrogenated An oil seal having a lip portion for sealing constituted by an elastomer composition composed of an elastomer such as nitrile rubber and a blend thereof and a silicate compound is disclosed.
- ACM and FKM are preferable as the elastomer.
- Patent Document 2 discloses an oil seal used in an engine in which a rubber lip portion is made of silicone rubber or fluorine rubber.
- Patent Document 3 proposes a method of forming a fluororesin coating film on the surface of rubber for the purpose of reducing the sliding resistance of the seal lip portion of the oil seal.
- Patent Document 4 is an automotive engine oil seal provided with an elastic member having a seal lip portion provided with at least a main lip portion, and the elastic member is made of a composition containing fluororubber and fluororesin, And it has a convex part on the surface of the said main lip part at least, and the said convex part consists of the fluororesin substantially contained in the said composition, and the said fluororesin is based on the polymerization unit based on ethylene, and tetrafluoroethylene
- An automotive engine oil seal is disclosed which is a copolymer including polymerized units, and the fluororubber is a polymer including polymerized units based on vinylidene fluoride.
- Patent Document 5 discloses a seal member made of an elastic body such as nitrile rubber, acrylic rubber, silicone rubber, or fluororubber and having a seal lip.
- Patent Document 6 is an automotive transmission oil seal provided with an elastic member having a seal lip portion provided with at least a main lip portion, and the elastic member is made of a composition containing fluororubber and fluororesin, And it has a convex part on the surface of the said main lip part at least, and the said convex part consists of the fluororesin substantially contained in the said composition, and the said fluororesin is based on the polymerization unit based on ethylene, and tetrafluoroethylene
- a transmission oil seal for automobiles is disclosed, which is a copolymer including polymerized units, and the fluororubber is a polymer including polymerized units based on vinylidene fluoride.
- Patent Document 7 As a valve stem seal, for example, in Patent Document 7, a diamond-like hard carbon film is formed on the inner peripheral surface of a seal member that is externally fitted to the valve stem for the purpose of reducing sliding resistance between the seal member and the valve stem.
- a sliding part structure for forming a film layer is disclosed.
- Patent Literature 8 discloses a valve stem seal having a fluororesin film on the inner sliding surface of the seal lip portion.
- a part or the whole including a sliding surface of a valve stem oil seal material is made of thermoplastic fluororesin, fluororubber and low molecular weight fluoropolymer.
- Patent Document 10 discloses a valve stem seal for an automobile including an elastic member that is disposed at an end of a valve stem guide and has a seal lip portion that is slidably in close contact with an engine valve stem, and the elastic member includes: It consists of a composition containing fluororubber and fluororesin, and has a convex part on at least the surface of the seal lip part, and the convex part consists essentially of a fluororesin contained in the composition,
- An automotive valve stem seal is disclosed, which is a copolymer including a polymerization unit based on ethylene and a polymerization unit based on tetrafluoroethylene, and the fluororubber is a polymer including a polymerization unit based on vinylidene fluoride. Yes.
- Patent Document 11 includes fluororubber and fluororesin, and the fluororubber and fluororesin are obtained by co-coagulation of fluororubber and fluororesin, and a crosslinkable fluororubber composition, and A fluororubber molded product obtained by crosslinking the crosslinkable fluororubber composition is disclosed.
- Patent Document 11 does not describe that an oil seal for automobiles is specifically manufactured.
- Patent Documents 4, 6 and 10 have a convex portion substantially made of a fluororesin on the surface of the seal lip portion, and the fluororesin includes a polymer unit based on ethylene and a polymer unit based on tetrafluoroethylene.
- An automotive engine oil seal or the like, which is a copolymer, is disclosed, and it is described that excellent sliding characteristics can be obtained by having this convex portion.
- further improvement in sliding characteristics has been demanded for oil seals for automobiles.
- An object of this invention is to provide the oil seal for motor vehicles which is excellent in low slidability as well as sealing performance.
- the present invention is an oil seal for automobiles provided with an elastic member having a seal lip portion, wherein the elastic member is made of a composition containing fluororubber and fluororesin, and protrudes at least on the surface of the seal lip portion. And the convex part is made of a fluororesin substantially contained in the composition, and the fluororesin is a copolymer containing a polymer unit based on tetrafluoroethylene and a polymer unit based on hexafluoropropylene.
- An oil seal for automobiles is provided.
- oil seal for automobiles of the present invention has the above-described configuration, it has excellent low sliding properties as well as sealing properties.
- FIG. 3 is a perspective view of the automobile engine oil seal shown in FIG. 2.
- FIG. 10 is a cross-sectional view of the automotive valve stem seal of the present invention shown in FIG. 9. It is sectional drawing which shows the usage aspect of the valve stem seal for motor vehicles typically, and is an enlarged view of the B area
- the automotive oil seal of the present invention is an automotive oil seal provided with an elastic member having a seal lip portion, and the elastic member is made of a composition containing fluororubber and fluororesin, and at least the seal lip
- the surface of the part has a convex part, and the convex part is made of a fluororesin substantially contained in the composition, and the fluororesin comprises a polymer unit based on tetrafluoroethylene and a polymer unit based on hexafluoropropylene. It is a copolymer containing.
- the oil seal for automobiles of the present invention has a convex portion made of the specific fluororesin on the surface of the seal lip portion, in the sliding portion where the seal lip portion closely contacts the crankshaft, the axle, the engine valve stem, etc.
- the oil trap effect of lubricating oil is promoted. Therefore, it becomes an oil seal for automobiles having an extremely excellent low slidability in the sliding portion.
- the automobile oil seal of the present invention is used as an automobile engine oil seal or an automobile transmission oil seal, the rotational torque can be made extremely small. Further, when used as a valve stem seal for automobiles, the stroke load can be reduced.
- each component of the oil seal for automobiles of the present invention will be described in detail.
- Fluoro rubber is usually made of an amorphous polymer having fluorine atoms bonded to carbon atoms constituting the main chain and having rubber elasticity.
- the fluororubber may be composed of one kind of polymer or may be composed of two or more kinds of polymers.
- Fluorororubber is vinylidene fluoride (VdF) / hexafluoropropylene (HFP) copolymer, VdF / HFP / tetrafluoroethylene (TFE) copolymer, TFE / propylene copolymer, TFE / propylene / VdF copolymer.
- Ethylene / HFP copolymer Ethylene / HFP copolymer, ethylene / HFP / VdF copolymer, ethylene / HFP / TFE copolymer, VdF / TFE / perfluoro (alkyl vinyl ether) (PAVE) copolymer, and VdF / chlorotrifluoro It is preferably at least one selected from the group consisting of ethylene (CTFE) copolymers.
- CTFE ethylene
- a fluororubber made of a copolymer containing VdF units is more preferable because it provides an excellent oil seal for automobiles with low slidability.
- VdF-based fluororubber made of a copolymer containing the vinylidene fluoride (VdF) unit will be described.
- the VdF-based fluororubber is a fluororubber containing at least polymerized units derived from VdF.
- the copolymer containing a VdF unit is preferably a copolymer containing a VdF unit and a copolymer unit derived from a fluorine-containing ethylenic monomer (excluding the VdF unit).
- the copolymer containing a VdF unit preferably further contains a copolymer unit derived from a monomer copolymerizable with VdF and a fluorine-containing ethylenic monomer.
- the copolymer containing VdF units preferably contains 30 to 90 mol% of VdF units and 70 to 10 mol% of copolymerized units derived from a fluorine-containing ethylenic monomer, and 30 to 85 mol% of VdF units. More preferably, it contains 30 to 15 mol% of a copolymerized unit derived from a fluorine-containing ethylenic monomer, and 30 to 80 mol% of a VdF unit and 70 to 20 mol% of a fluorine-containing ethylenic monomer.
- the copolymerized unit derived from the monomer copolymerizable with VdF and the fluorine-containing ethylenic monomer is 0 to 10 mol based on the total amount of the VdF unit and the copolymerized unit derived from the fluorine-containing ethylenic monomer. % Is preferred.
- a fluoroalkyl group having 1 to 6 carbon atoms which may contain 1 to 2 carbon atoms, or 1 to 2 atoms selected from the group consisting of H, Cl, Br and I
- a fluorine-containing monomer such as a fluorovinyl ether represented by (C) represents a cyclic fluoroalkyl group having 5 or 6 carbon atoms.
- at least one selected from the group consisting of fluorovinyl ether represented by formula (1), TFE, HFP and PAVE is preferable, and at least selected from the group consisting of TFE, HFP and PAVE One type is more preferable.
- CF 2 CFO (CF 2 CFY 1 O) p - (CF 2 CF 2 CF 2 O) q -Rf (2) (Wherein Y 1 represents F or CF 3 , Rf represents a perfluoroalkyl group having 1 to 5 carbon atoms, p represents an integer of 0 to 5, and q represents an integer of 0 to 5) It is preferable that
- the PAVE is preferably perfluoro (methyl vinyl ether) or perfluoro (propyl vinyl ether), and more preferably perfluoro (methyl vinyl ether). These can be used alone or in any combination.
- Examples of the monomer copolymerizable with VdF and the fluorine-containing ethylenic monomer include ethylene, propylene, and alkyl vinyl ether.
- a copolymer containing such a VdF unit is a copolymer containing a polymer unit based on VdF and a polymer unit based on at least one monomer selected from the group consisting of TFE, HFP, and PAVE. It is preferably a coalescence. Specifically, VdF / HFP copolymer, VdF / HFP / TFE copolymer, VdF / CTFE copolymer, VdF / CTFE / TFE copolymer, VdF / PFE copolymer, VdF / TFE / PAVE copolymer.
- At least one copolymer selected from the group consisting of a polymer, a VdF / HFP / PAVE copolymer, and a VdF / HFP / TFE / PAVE copolymer is preferred.
- these copolymers containing VdF units at least one copolymer selected from the group consisting of VdF / HFP copolymers and VdF / HFP / TFE copolymers from the viewpoint of heat resistance. Is particularly preferred. It is preferable that the copolymer containing these VdF units satisfies the composition ratio of the above-described VdF units and copolymer units derived from a fluorine-containing ethylenic monomer.
- the VdF / HFP copolymer preferably has a VdF / HFP molar ratio of 45 to 85/55 to 15, more preferably 50 to 80/50 to 20, and still more preferably 60 to 80/40. ⁇ 20.
- the VdF / HFP / TFE copolymer preferably has a VdF / HFP / TFE molar ratio of 40 to 80/10 to 35/10 to 35.
- VdF / PAVE copolymer As the VdF / PAVE copolymer, a VdF / PAVE molar ratio of 65 to 90/10 to 35 is preferable.
- VdF / TFE / PAVE copolymer As the VdF / TFE / PAVE copolymer, a VdF / TFE / PAVE molar ratio of 40 to 80/3 to 40/15 to 35 is preferable.
- VdF / HFP / PAVE copolymer those having a molar ratio of VdF / HFP / PAVE of 65 to 90/3 to 25/3 to 25 are preferable.
- the VdF / HFP / TFE / PAVE copolymer preferably has a VdF / HFP / TFE / PAVE molar ratio of 40 to 90/0 to 25/0 to 40/3 to 35, more preferably 40 to 80/3 to 25/3 to 40/3 to 25.
- the fluororubber is made of a copolymer containing a copolymer unit derived from a monomer that provides a crosslinking site.
- the monomer that gives a crosslinking site include perfluoro (6,6-dihydro-6-iodo-3-oxa-1-) described in JP-B-5-63482 and JP-A-7-316234.
- Hexene) and perfluoro (5-iodo-3-oxa-1-pentene) -containing monomers bromine-containing monomers described in JP-A-4-505341, JP-A-4-505345, Examples include cyano group-containing monomers, carboxyl group-containing monomers, and alkoxycarbonyl group-containing monomers as described in JP-T-5-500070.
- the fluororubber is also preferably a fluororubber having an iodine atom or a bromine atom at the end of the main chain.
- Fluororubber having iodine atom or bromine atom at the main chain end is produced by adding a radical initiator in the presence of a halogen compound in an aqueous medium in the absence of oxygen and performing emulsion polymerization of the monomer. it can.
- halogen compound used include, for example, the general formula: R 2 I x Br y (Wherein x and y are each an integer of 0 to 2 and satisfy 1 ⁇ x + y ⁇ 2, and R 2 is a saturated or unsaturated fluorohydrocarbon group having 1 to 16 carbon atoms, carbon A saturated or unsaturated chlorofluorohydrocarbon group having 1 to 16 carbon atoms, a hydrocarbon group having 1 to 3 carbon atoms, or a cyclic hydrocarbon group having 3 to 10 carbon atoms which may be substituted with an iodine atom or a bromine atom And these may contain an oxygen atom).
- halogen compound examples include 1,3-diiodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4- Dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2 - diiodoethane, 1,3-diiodo -n- propane, CF 2 Br 2, BrCF 2 CF 2 Br, CF 3 CFBrCF 2 Br, CFClBr 2, BrCF 2 CFClBr, CFBrClCFClBr, BrCF 2 CF 2 CF
- 1,4-diiodoperfluorobutane or diiodomethane from the viewpoint of polymerization reactivity, crosslinking reactivity, availability, and the like.
- the fluororubber has a Mooney viscosity (ML 1 + 10 (100 ° C.)) of preferably from 5 to 140, more preferably from 10 to 120, and even more preferably from 20 to 100, from the viewpoint of good processability. preferable.
- Mooney viscosity can be measured according to ASTM-D1646. Measuring equipment: ALPHA2000 TECHNOLOGIES MV2000E rotor speed: 2 rpm Measurement temperature: 100 ° C
- compounding agents incorporated in the fluororubber for example, fillers, processing aids, plasticizers, colorants, stabilizers, adhesion aids, mold release agents, imparting conductivity.
- Various additives such as an agent, a thermal conductivity imparting agent, a surface non-adhesive agent, a flexibility imparting agent, a heat resistance improving agent, and a flame retardant may be blended. What is necessary is just to use these additives and a compounding agent in the range which does not impair the effect of this invention.
- Fluororesin A fluororesin is a copolymer (hereinafter also referred to as “FEP”) including polymerized units based on tetrafluoroethylene (TFE) and polymerized units based on hexafluoropropylene (HFP).
- FEP a copolymer
- TFE tetrafluoroethylene
- HFP hexafluoropropylene
- the fluororesin is preferably a perfluorofluororesin because it becomes an oil seal for automobiles having a lower slidability.
- the FEP is preferably a copolymer comprising 70 to 99 mol% of TFE units and 1 to 30 mol% of HFP units, and a copolymer comprising 80 to 97 mol% of TFE units and 3 to 20 mol% of HFP units. It is more preferable that If the TFE unit is less than 70 mol%, the mechanical properties tend to decrease, and if it exceeds 99 mol%, the melting point becomes too high and the moldability tends to decrease.
- FEP may be a copolymer comprising TFE, HFP, and a monomer copolymerizable with TFE and HFP.
- CF 2 CF-ORf 6 (wherein Rf 6 represents a perfluoroalkyl group having 1 to 5 carbon atoms.) Perfluoro (alkyl vinyl ether) [PAVE]
- the PAVE is selected from the group consisting of perfluoro (methyl vinyl ether) [PMVE], perfluoro (ethyl vinyl ether) [PEVE], perfluoro (propyl vinyl ether) [PPVE], and perfluoro (butyl vinyl ether). It is preferably at least one, and more preferably at least one selected from the group consisting of PMVE, PEVE and PPVE.
- alkyl perfluorovinyl ether derivative those in which Rf 7 is a perfluoroalkyl group having 1 to 3 carbon atoms are preferable, and CF 2 ⁇ CF—OCH 2 —CF 2 CF 3 is more preferable.
- the monomer units derived from monomers copolymerizable with TFE and HFP are 0.1 to 10 mol. It is preferable that the total of TFE units and HFP units is 90 to 99.9 mol%. If the copolymerizable monomer unit is less than 0.1 mol%, the moldability, environmental stress crack resistance and stress crack resistance tend to be inferior, and if it exceeds 10 mol%, heat resistance, mechanical properties and productivity. Tend to be inferior.
- the monomer units derived from monomers copolymerizable with TFE and HFP are 0.1 to 9 mol%. More preferably, the total of TFE units and HFP units is 91 to 99.9 mol%.
- the melting point of the fluororesin is preferably equal to or higher than the crosslinking temperature of the fluorororubber. As long as the melting point of the fluororesin is equal to or higher than the crosslinking temperature of the fluororubber, a preferable range varies depending on the type of the fluororubber, but is preferably 150 ° C or higher, and more preferably 180 ° C or higher. The upper limit is not particularly limited, but may be 300 ° C.
- the melting point of the fluororesin is preferably 230 ° C. or lower and more preferably 220 ° C. or lower because a lower oil sliding oil seal can be obtained.
- the fluororesin melts at the time of cross-linking molding, and there is a possibility that a desired shape oil seal for automobiles cannot be obtained. Moreover, there is a possibility that an automobile oil seal having a sufficient number of convex portions on the surface of the seal lip portion cannot be obtained.
- the fluororesin preferably has a melt flow rate [MFR] at 327 ° C. of 0.3 to 100 g / 10 min. If the MFR is too small, it may be difficult to have sufficient protrusions on the surface and the low slidability may be poor, and if the MFR is too large, molding may be difficult.
- the MFR is a value obtained by measuring at a temperature of 327 ° C. and a load of 5 kg in accordance with ASTM D3307-1. When the melting point of the fluororesin is less than 200 ° C., the MFR is measured at 280 ° C. In that case, the fluororesin preferably has an MFR at 280 ° C. of 0.3 to 100 g / 10 min.
- the MFR is a value obtained by measuring at a temperature of 280 ° C. and a load of 5 kg in accordance with ASTM D3307-1.
- the oil seal for automobiles preferably has a small compression set to prevent the oil seal from coming off from the housing.
- the fluororesin is preferably at least one selected from the group consisting of fluororesins (B1) and (B2) having the following specific composition.
- the fluororesins (B1) and (B2) are copolymers composed of tetrafluoroethylene (TFE) units and hexafluoropropylene (HFP) units having a specific composition.
- the fluororesin (B1) or (B2) having a specific composition By using the fluororesin (B1) or (B2) having a specific composition, the low slidability of the automotive oil seal of the present invention can be further improved, and at the same time, the low compression set of the automotive oil seal Can be improved.
- the fluororesins (B1) and (B2) are preferable from the viewpoint of excellent compatibility with fluororubber and the heat resistance of the oil seal for automobiles.
- the fluororesin (B1) is a polymer composed of only the TFE unit (a) and the HFP unit (b), and the TFE unit (a) / HFP unit (b) has a molar ratio of 80.0 to 87.3 / It is a copolymer of 12.7 to 20.0.
- the fluororesin (B1) having the composition in the specific range is used, the compression set of the oil seal for automobiles is significantly reduced.
- the fluororesin (B1) has a molar ratio of (8) to 87.0 / 13.0 in terms of (a) / (b) from the viewpoint of further reducing the compression set and improving the mechanical properties. 13.0 to 18.0, preferably 83.0 to 86.5 / 13.5 to 17.0, more preferably 83.0 to 86.0 / 14.0 to 17.0. Is more preferable. If (a) / (b) is too large, the compression set of the oil seal for automobiles may not be sufficiently reduced. If (a) / (b) is too small, the mechanical properties tend to decrease.
- the fluororesin (B2) is a copolymer comprising a tetrafluoroethylene unit (a), a hexafluoropropylene unit (b), and a polymer unit (c) based on a monomer copolymerizable with tetrafluoroethylene and hexafluoropropylene.
- the fluororesin (B2) has a molar ratio of (8) to 88.0 / 12 in terms of (a) / (b) from the viewpoint of further reducing the compression set and improving the mechanical properties. It is preferably from 0.0 to 18.0, more preferably from 84.0 to 88.0 / 12.0 to 16.0. If the TFE unit (a) / HFP unit (b) is too large, the compression set of the oil seal for automobiles may not be sufficiently reduced. Further, the melting point becomes too high, and the moldability tends to decrease. If the TFE unit (a) / HFP unit (b) is too small, the mechanical properties tend to decrease.
- (c) / ⁇ (a) + (b) ⁇ is preferably 0.3 to 8.0 / 92.0 to 99.7 in terms of molar ratio.
- the polymerized unit (c) based on the monomer copolymerizable with TFE and HFP is preferably a PAVE unit.
- the fluororesin (B2) is more preferably a copolymer composed only of TFE units, HFP units, and PAVE units.
- the fluororesins (B1) and (B2) preferably have a melting point of 210 ° C. or lower.
- the melting point is more preferably 130 to 210 ° C., further preferably 150 to 200 ° C., and particularly preferably 160 to 190 ° C. If the melting point of the fluororesin is less than 130 ° C., bleeding may occur at the time of cross-linking molding, and sufficient low slidability may not be obtained. If it exceeds 210 ° C., the storage elastic modulus of the fluororesin increases, and the low compression set of the oil seal for automobiles may be impaired.
- the fluororesins (B1) and (B2) preferably have a storage elastic modulus (E ′) at 70 ° C. by dynamic viscoelasticity measurement of 10 to 160 MPa from the viewpoint of reducing the compression set of the oil seal for automobiles.
- the storage elastic modulus is a value measured at 70 ° C. by dynamic viscoelasticity measurement. More specifically, a sample having a length of 30 mm, a width of 5 mm, and a thickness of 0.5 mm was pulled in a tensile mode, a grip width of 20 mm, and a measurement temperature of 25 ° C. to 200 ° C. It is a value measured under conditions of a speed of 2 ° C./min and a frequency of 1 Hz.
- a preferable storage elastic modulus (E ′) at 70 ° C. is 10 to 160 MPa, a more preferable storage elastic modulus (E ′) is 20 to 140 MPa, and a further preferable storage elastic modulus (E ′) is 30 to 100 MPa.
- the elastic member is made of a composition containing fluororubber and fluororesin, and has a convex portion at least on the surface of the seal lip portion, and the convex portion is made of a fluororesin substantially contained in the composition. Since the convex portion exists on the surface of the seal lip portion, the oil seal for automobiles of the present invention has an excellent low sliding property.
- a convex part consists of a fluororesin substantially contained in the said composition.
- a convex part can be formed by depositing the fluororesin contained in the crosslinkable composition obtained by the mixing process (I) mentioned later on the surface, for example with the manufacturing method of the oil seal for cars mentioned below.
- the convex part does not have a clear interface with the seal lip part, and the convex part and the seal lip part are integrally configured, and the convex part is unlikely to drop off or be lost. The effect can be enjoyed more reliably.
- 1 (a) is the shape of the convex portion seal lip portion having a perspective view schematically showing, (b) it is a plane including the straight line B 1 and the line B 2 perpendicular to the surface of (a) a sectional view of the convex portion 11 is a sectional view taken along a plane including the (c) linear C 1 and the line C 2 surface parallel of (a).
- 1A to 1C schematically depict a minute region on the surface of the seal lip portion. As shown in FIGS. 1A to 1C, for example, a substantially conical (cone-shaped) convex portion 11 is formed on the surface of the seal lip portion.
- the height of the convex portion 11 refers to the height of the portion protruding from the surface of the seal lip portion (see H in FIG. 1B). Further, the bottom cross-sectional area of the projections 11, the projections 11 of the convex portion 11 is observed in the cut surface with a sealing lip of the plane parallel to the surface (straight line C 1 and the line C 2 and the plane including) (Refer to FIG. 1C).
- the area ratio (occupation ratio of the convex portion) of the region having the convex portion occupying the surface of the seal lip portion is 0.06 (6%) or more.
- a more preferable area ratio is 0.15 (15%) or more, further preferably 0.20 (20%) or more, particularly preferably 0.25 (25%) or more, and most preferably 0.8. 30 (30%) or more.
- region which has the convex part which occupies for the surface of the said seal lip part says the ratio of the area which a convex part occupies in the cut surface which evaluates the bottom part cross-sectional area of the said convex part.
- the volume ratio of the fluororesin is preferably 0.05 to 0.45 (5 to 45% by volume) with respect to the seal lip part.
- the lower limit of the volume ratio is more preferably 0.10 (10% by volume), still more preferably 0.15 (15% by volume), and particularly preferably 0.20 (20% by volume).
- the upper limit of the volume ratio is more preferably 0.40 (40% by volume), still more preferably 0.35 (35% by volume), and particularly preferably 0.30 (30% by volume).
- the fluororesin is a copolymer comprising polymerized units based on tetrafluoroethylene and polymerized units based on hexafluoropropylene, and has excellent heat resistance.
- the volume ratio of the fluororesin in the seal lip portion is regarded as the same as the volume ratio of the fluororesin contained in the cross-linkable composition described later. Can do.
- the area ratio of the region having the convex portion occupying the surface of the seal lip portion is a volume ratio of the fluororesin occupying the seal lip portion, that is, a composition containing fluororubber and fluororesin. It is preferably 1.2 times or more and more preferably 1.3 times or more of the volume ratio of the fluororesin occupied. This is because the ratio of the region having the convex portion on the surface of the seal lip portion is higher than the volume ratio of the fluororesin in the seal lip portion, that is, the volume ratio of the fluororesin to the composition containing the fluororubber and the fluororesin. Means higher than that.
- the oil seal for automobiles of the present invention improves the low slidability, which was a disadvantage of fluororubber, even when the mixing ratio of fluororesin is small, and the elasticity that is an advantage of fluororubber is impaired.
- region which has the said convex part is achieved in the seal lip part, the effect of this invention will be fully show
- the convex portion preferably has a height of 0.1 to 30.0 ⁇ m.
- the height is more preferably 0.3 to 20.0 ⁇ m, still more preferably 0.5 to 10.0 ⁇ m.
- the convex part preferably has a bottom sectional area of 0.1 to 2000 ⁇ m 2 .
- the oil seal for automobiles of the present invention is more excellent in low slidability.
- a more preferable bottom cross-sectional area is 0.3 to 1500 ⁇ m 2
- a still more preferable bottom cross-sectional area is 0.5 to 1000 ⁇ m 2 .
- the seal lip portion preferably has a standard deviation of the height of the convex portion of 0.300 or less. Within this range, the oil seal for automobiles of the present invention is more excellent in low slidability.
- the number of convex portions of the seal lip portion is preferably 500 to 60000 pieces / mm 2 .
- a more preferable lower limit is 2000 pieces / mm 2
- a further preferable lower limit is 4000 pieces / mm 2 .
- the oil seal for automobiles of the present invention is more excellent in low slidability.
- the area ratio, the height of the convex portion, the sectional area of the bottom portion of the convex portion, the number of convex portions, etc. for example, manufactured by Keyence Corporation, using a color 3D laser microscope (VK-9700) as analysis software WinRooF Ver. It can be calculated using 6.4.0.
- the area ratio of the region having the convex part is obtained as the ratio of the total cross-sectional area to the total cross-sectional area value obtained by calculating the bottom cross-sectional area of the convex part.
- the number of convex portions is obtained by converting the number of convex portions in the measurement region into a number per 1 mm 2 .
- Examples of the oil seal for automobiles of the present invention include an engine oil seal for automobiles, a transmission oil seal for automobiles, and a valve stem seal for automobiles.
- the oil seal for automobiles of the present invention is an engine oil seal for automobiles, wherein the elastic member is provided with at least a main lip portion at a seal lip portion, and has a convex portion at least on the surface of the main lip portion. It is preferable.
- improvement in sliding characteristics of automobile engine oil seals has been desired. There is a need for improved sliding characteristics over the entire range of low to high engine speeds.
- the oil seal for automobiles of the present invention has the above-described configuration, it has excellent sliding characteristics over the entire range from the low rotation range to the high rotation range of the engine. For this reason, it is suitable for an engine oil seal for automobiles where torque during rotation is very small and low fuel consumption is desired. Accordingly, the oil seal for automobiles of the present invention is particularly preferably an engine oil seal for automobiles.
- FIG. 2 is a cross-sectional view schematically showing how the engine oil seal for automobiles is used, and is an enlarged view of region A shown in FIG. 3 is a cross-sectional view schematically showing an engine using the automotive engine oil seal and automotive valve stem seal of the present invention, and FIG. 4 is a perspective view of the automotive engine oil seal shown in FIG. is there.
- the automobile engine oil seal of FIG. 2 is a drawing of a cross section taken along line AA of FIG.
- the engine oil seal 21 for automobiles has an annular structure having a substantially U-shaped radial cross section, and is made of an elastic composition made of a composition containing a fluororesin and a fluororubber.
- a member 22, an annular metal ring 26 and a ring spring 27 are provided.
- the elastic member 22 is in close contact with the housing 20 and a seal lip portion provided with a main lip portion 23 having a wedge-shaped radial cross section that abuts against the crankshaft 29 and a sub lip portion 25 projecting inward along the circumferential direction.
- a fitting portion 24 is provided.
- the metal ring 26 is built in the elastic member 22, and thereby serves to reinforce the automobile engine oil seal 21.
- the ring spring 27 is disposed on the outer peripheral surface side of the main lip portion 23, and the main lip portion 23 comes into contact with the crankshaft 29 by the urging force of the ring spring 27.
- the engine oil seal 21 for an automobile has a main lip portion 23 slidably abutting against a crankshaft 29 of the engine 30 with the main lip portion 23 positioned on the inner side of the engine 30 and the sub lip portion 25 positioned on the outer side.
- the fitting portion 24 is press fitted into the gap between the crankshaft 29 and the housing 20 so that the fitting portion 24 is in close contact with the housing 20.
- 32 is a crank pulley
- 33 is a connecting rod
- 34 is a piston
- 35 is a valve.
- the engine oil seal 21 for an automobile is formed of a composition in which the elastic member 22 includes fluororesin and fluororubber, and a convex portion (see FIG. 5) is formed on the surface of the seal lip portion having the main lip portion 23 and the sub lip portion 25. 1). That is, the automobile engine oil seal 21 has a convex portion at the contact portion with the crankshaft 29.
- the material of the main lip 23 of the engine oil seal 21 for automobiles is a composition containing the specific fluororesin and fluororubber. Therefore, the sliding characteristics are superior to those of other conventionally known automotive engine oil seal materials, such as nitrile rubber, acrylic rubber, and fluororubber containing no fluororesin.
- the automobile engine oil seal 21 has a convex portion made of the above composition.
- the seal lip portion since the deformation of the seal lip portion follows the rotation of the crankshaft, the seal lip portion is also easily deformed when the crankshaft is rotating at a high rotational speed, and oil enters between the two. It becomes easy.
- the seal lip portion when the rotation speed of the crankshaft is low, the seal lip portion is less likely to be deformed than when the rotation speed is high, and as a result, there is oil between the crankshaft and the seal lip portion. It becomes difficult to intervene. For this reason, when the rotation speed of the crankshaft is low, the sliding characteristics tend to be inferior to those when the rotation speed is high, and in the engine oil seal for automobiles, the rotation speed of the crankshaft is particularly low. Improvement of sliding characteristics in the case of numbers is desired.
- the engine oil seal for automobiles of the present invention has a convex portion made of the specific fluororesin on the surface of the seal lip portion. Microscopically, there is a very small gap between the seal lip and the crankshaft while ensuring the essential function of preventing leakage, and it is easy to deform following the rotation of the crankshaft. It will have a structure. Therefore, in the engine oil seal for automobiles of the present invention, oil is likely to intervene between the engine oil seal for automobiles and the crankshaft, and the entire range from low to high rpm is obtained regardless of the rpm of the crankshaft. Therefore, it has excellent sliding characteristics.
- the use location of the engine oil seal for automobiles of the present invention is not limited to the crankshaft. For example, when the engine includes a cam shaft, the engine oil seal for automobiles that slides with the cam shaft should also be used. Can do.
- the oil seal for automobiles of the present invention is a transmission oil seal for automobiles, and the elastic member is provided with at least a main lip portion at a seal lip portion, and has at least a convex portion on the surface of the main lip portion. Is preferred.
- transmission oil seals for automobiles are used at low to high speeds. There is a need for improved sliding characteristics over the entire area.
- the oil seal for automobiles of the present invention Since the oil seal for automobiles of the present invention has the above-described configuration, it has excellent sliding characteristics over the entire region from low speed traveling to high speed traveling. Therefore, it is suitable for a transmission oil seal for automobiles in which torque during rotation is very small and low fuel consumption is desired. Therefore, the oil seal for automobiles of the present invention is particularly preferably a transmission oil seal for automobiles.
- FIG. 5 is a cross-sectional view schematically showing how the transmission oil seal for automobiles is used, and is an enlarged view of region C shown in FIG. 6 is a cross-sectional view schematically showing a transmission using an automobile transmission oil seal, and FIG. 7 is a perspective view of the automobile transmission oil seal shown in FIG.
- the automobile transmission oil seal in FIG. 5 is a drawing of a cross section taken along line BB in FIG.
- the automobile transmission oil seal 51 has an annular structure having a substantially U-shaped radial cross section, and is made of a composition containing a fluororesin and a fluororubber.
- a member 52, an annular metal ring 56, and a ring spring 57 are provided.
- the elastic member 52 has a seal lip portion provided with a main lip portion 53 having a wedge-shaped radial cross section in contact with the axle 59 on the inner peripheral side, and a fitting portion 54 that is in close contact with the housing 50 on the outer peripheral side.
- the metal ring 56 is incorporated in the elastic member 52, and thereby plays a role of reinforcing the automobile transmission oil seal 51.
- the ring spring 57 is disposed on the outer peripheral surface side of the main lip portion 53, and the main lip portion 53 comes into contact with the axle 59 by the urging force of the ring spring 57.
- the transmission oil seal 51 for an automobile is arranged so that the ring spring 57 is exposed to the inside of the transmission 60, the main lip portion 53 is slidably contacted with the axle 59 of the transmission 60, and the fitting portion 54 is in close contact with the housing 50.
- 62 is a main shaft (input shaft) connected to the crankshaft
- 63 is a counter shaft (output shaft) arranged in parallel with the main shaft.
- the transmission oil seal 51 for automobiles is slidably disposed not only on the axle 59 but also on the main shaft 62 and the counter shaft 63 as shown in FIG.
- the elastic member 52 is made of a composition containing fluororesin and fluororubber, and the surface of the seal lip portion having the main lip portion 53 has a convex portion (see FIG. 1). is doing. That is, the automobile transmission oil seal 51 has a convex portion at the contact portion with the axle 59.
- the transmission oil seal 51 for motor vehicles has the said convex part, a friction coefficient between shafts (an axle, a main shaft, a counter shaft) is small, and it is excellent in a sliding characteristic.
- shaft simply includes an axle, a main shaft, and a counter shaft. The effect of being excellent in the sliding characteristics can be exerted over the entire range from the low rotational speed to the high rotational speed regardless of the rotational speed of the shaft. I will explain this in more detail.
- the material of the main lip portion 53 of the automobile transmission oil seal 51 is a composition containing fluororesin and fluororubber.
- the transmission oil seal 51 for automobiles has a convex portion made of the above composition.
- oil is interposed (an oil film is formed) between the automobile transmission oil seal and the shaft. And it is thought that this oil functions as a lubricant between both.
- the transmission oil seal for automobiles can be slid with a low frictional resistance due to the presence of oil.
- the seal lip portion is in contact with the shaft without any gap. Therefore, in order for oil to intervene between the transmission oil seal for automobiles and the shaft from this state, the seal lip portion is deformed, and oil can enter between the seal lip portion and the shaft following this deformation. Necessary.
- the deformation of the seal lip portion follows the rotation of the shaft, the seal lip portion is also easily deformed when the shaft is rotating at a high rotation speed, and oil easily enters between the two. .
- the transmission oil seal for automobiles of the present invention has a convex portion made of the specific fluororesin on the surface of the seal lip portion.
- the oil seal for automobiles of the present invention is an automobile valve stem seal disposed at the end of the valve stem guide of the engine, and the seal lip portion may be slidably in close contact with the valve stem of the engine. preferable.
- it has been desired to improve the sliding characteristics of automotive valve stem seals. Improvement is demanded.
- it is also required to have excellent wear resistance.
- the oil seal for automobiles of the present invention Since the oil seal for automobiles of the present invention has the above-described configuration, it has excellent low slidability and further excellent wear resistance. Therefore, it is suitable for the valve stem seal for automobiles. Therefore, the oil seal for automobiles of the present invention is particularly preferably an automobile valve stem seal.
- an embodiment of an automotive valve stem seal of the present invention will be described with reference to the drawings.
- FIG. 9 is a cross-sectional view schematically showing how the automotive valve stem seal of the present invention is used, and is an enlarged view of region B shown in FIG.
- FIG. 3 is a cross-sectional view schematically showing an engine using the automotive valve stem seal of the present invention
- FIG. 8 is a cross-sectional view of the automotive valve stem seal shown in FIG.
- the automotive valve stem seal 81 of the present invention is provided with a mounting ring 87 so as to be attached to one end (see FIG. 9) of the valve stem guide 83 in the axial direction.
- An elastic member 86 made of a composition containing a fluororesin and fluororubber is bonded to the ring 87.
- the elastic member 86 includes a seal lip portion 86 a that is in close contact with the outer peripheral surface of the valve stem 82, and a stationary seal portion 86 b that is in close contact with the outer peripheral surface of the valve stem guide 83.
- a tension force is applied to the valve stem 82 by a spring spring 88 provided around the seal lip portion 86a.
- the elastic member can be obtained by crosslinking a crosslinkable composition containing uncrosslinked fluororubber and fluororesin.
- the oil seal for automobiles of the present invention is preferably obtained by a production method described later.
- the oil seal for automobiles of the present invention is (I) a step of mixing a fluororesin and uncrosslinked fluororubber,
- An elastic member having a predetermined shape is formed by a method including (II) a molding crosslinking step for molding and crosslinking the obtained mixture, and (III) a heat treatment step for heating the obtained crosslinked molding to a temperature equal to or higher than the melting point of the fluororesin.
- the uncrosslinked fluororubber is a fluororubber before crosslinking.
- the method for obtaining the crosslinkable composition is not particularly limited as long as a method capable of uniformly mixing the uncrosslinked fluororubber and the fluororesin is used.
- a method capable of uniformly mixing the uncrosslinked fluorororubber and the fluororesin is used.
- each of the uncrosslinked fluororubber and the fluororesin is obtained. It can be obtained by a method of mixing powders coagulated alone, a method of melt-kneading uncrosslinked fluororubber and fluororesin, a method of coaggregating uncrosslinked fluororubber and fluororesin, or the like.
- melt-kneading uncrosslinked fluororubber and fluororesin a method of melt-kneading uncrosslinked fluororubber and fluororesin or a method of co-coagulating uncrosslinked fluororubber and fluororesin is preferable.
- melt-kneading and co-coagulation will be described.
- melt-kneading The melt-kneading is performed with the uncrosslinked fluororubber and the fluororesin at a temperature that is at least 5 ° C. lower than the melting point of the fluororesin, preferably at a temperature that is equal to or higher than the melting point of the fluororesin.
- the upper limit of the heating temperature is less than the lower thermal decomposition temperature of uncrosslinked fluororubber or fluororesin.
- melt-kneading is not performed under conditions that cause crosslinking at that temperature (in the presence of a crosslinking agent, crosslinking accelerator, and acid acceptor, etc.), but crosslinking is caused at a melt-kneading temperature that is 5 ° C lower than the melting point of the fluororesin. If there are no components (for example, only a specific crosslinking agent, only a combination of a crosslinking agent and a crosslinking accelerator, etc.), they may be added and mixed during melt-kneading. Examples of conditions that cause crosslinking include a combination of a polyol crosslinking agent, a crosslinking accelerator, and an acid acceptor.
- melt-kneading uncrosslinked fluororubber and fluororesin are melt-kneaded to prepare a pre-compound (preliminary mixture), and then other additives and compounding agents are kneaded at a temperature lower than the crosslinking temperature.
- a two-stage kneading method using a compound (crosslinkable composition) is preferred.
- a method of kneading all the components at a temperature lower than the crosslinking temperature of the crosslinking agent may be used.
- Melt-kneading is performed by kneading with fluororubber at a temperature of 5 ° C. lower than the melting point of the fluororesin, for example, 180 ° C. or higher, usually 220 to 300 ° C., using a Banbury mixer, pressure kneader, extruder or the like. It can be carried out. Among these, it is preferable to use an extruder such as a pressure kneader or a twin screw extruder because a high shear force can be applied.
- full compounding in the two-stage kneading method can be performed using an open roll, a Banbury mixer, a pressure kneader, or the like at a temperature lower than the crosslinking temperature, for example, 100 ° C. or lower.
- Dynamic crosslinking is a method in which uncrosslinked rubber is blended in a matrix of thermoplastic resin, the uncrosslinked rubber is crosslinked while kneading, and the crosslinked rubber is dispersed microscopically in the matrix.
- the mixing step is preferably to obtain a crosslinkable composition containing the coagulated product after coaggregating the uncrosslinked fluororubber and the fluororesin to obtain a coagulated product.
- the crosslinkable composition containing the agglomerates By using the crosslinkable composition containing the agglomerates, the convex portions formed on the surface of the seal lip portion can be formed more uniformly and finely, and the area ratio (occupancy ratio) of the region having the convex portions ) Can be made sufficiently higher. As a result, an oil seal for automobiles having better low slidability can be obtained.
- the crosslinkable composition contains a coagulated product obtained by co-coagulation of uncrosslinked fluororubber and fluororesin, the uncrosslinked fluororubber and fluororesin are uniformly in the crosslinkable composition. Expected to be dispersed. It is considered that the automobile oil seal of the present invention having excellent low slidability can be obtained by cross-linking and heat-treating such a cross-linkable composition.
- Examples of the co-coagulation method include (i) a method in which an aqueous dispersion of uncrosslinked fluororubber and an aqueous dispersion of fluororesin are mixed and then coagulated, and (ii) a powder of uncrosslinked fluororubber is used. And (iii) a method of coagulating after adding the fluororesin powder to an aqueous dispersion of uncrosslinked fluororubber.
- the method (i) is preferable in that both the uncrosslinked fluororubber and the fluororesin are easily dispersed uniformly.
- the coagulation in the coagulation methods (i) to (iii) can be performed using, for example, a flocculant.
- a flocculant is not particularly limited, but examples thereof include aluminum salts such as aluminum sulfate and alum, calcium salts such as calcium sulfate, magnesium salts such as magnesium sulfate and magnesium chloride, sodium chloride and potassium chloride.
- known aggregating agents such as monovalent cation salts.
- the pH may be adjusted by adding an acid or an alkali in order to promote aggregation.
- the coagulated product obtained by co-coagulation of the uncrosslinked fluororubber and the fluororesin is coagulated after mixing, for example, an aqueous dispersion of uncrosslinked fluororubber and an aqueous dispersion of fluororesin,
- the coagulum can then be recovered and optionally obtained by drying.
- a crosslinking agent may be necessary.
- a composition may be obtained.
- the crosslinkable composition may contain a crosslinking agent used in each crosslinking system.
- the above-mentioned various additives may be included.
- the coagulated product and the crosslinking agent are mixed. The mixing can be performed at a temperature lower than the melting point of the fluororesin by, for example, a normal mixing method using a kneader or the like.
- the crosslinking system of the uncrosslinked fluororubber is preferably at least one selected from the group consisting of a peroxide crosslinking system and a polyol crosslinking system, for example. From the viewpoint of chemical resistance, a peroxide crosslinking system is preferred, and from the viewpoint of heat resistance, a polyol crosslinking system is preferred. Therefore, the crosslinking agent is preferably at least one crosslinking agent selected from the group consisting of polyol crosslinking agents and peroxide crosslinking agents. The amount of the crosslinking agent may be appropriately selected depending on the type of the crosslinking agent and the like, but is preferably 0.2 to 5.0 parts by mass, more preferably 0. 3 to 3.0 parts by mass.
- Peroxide crosslinking can be performed by using peroxide-crosslinkable uncrosslinked fluororubber and an organic peroxide as a crosslinking agent.
- the uncrosslinked fluorororubber capable of peroxide crosslinking is not particularly limited as long as it is an uncrosslinked fluororubber having a site capable of peroxide crosslinking.
- the site capable of peroxide crosslinking is not particularly limited, and examples thereof include a site having an iodine atom and a site having a bromine atom.
- the organic peroxide may be an organic peroxide that can easily generate a peroxy radical in the presence of heat or a redox system.
- 1,1-bis (t-butylperoxy) -3 5,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, ⁇ , ⁇ -bis (t- Butylperoxy) -p-diisopropylbenzene, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexyne -3, benzoyl peroxide, t-butyl peroxybenzene, t-butyl peroxymaleic acid, t-butyl peroxyisopropyl carbonate
- 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 2,5-dimethyl-2,5-di (t-butylperoxy) -hexyne-3 are preferable.
- the blending amount of the organic peroxide is preferably 0.1 to 15 parts by mass, more preferably 0.3 to 5 parts by mass with respect to 100 parts by mass of the uncrosslinked fluororubber.
- the cross-linkable composition preferably further contains a cross-linking aid.
- the crosslinking aid include triallyl cyanurate, triallyl isocyanurate (TAIC), triacryl formal, triallyl trimellitate, N, N′-m-phenylenebismaleimide, dipropargyl terephthalate, diallyl phthalate, Tetraallyl terephthalate amide, triallyl phosphate, bismaleimide, fluorinated triallyl isocyanurate (1,3,5-tris (2,3,3-trifluoro-2-propenyl) -1,3,5-triazine-2 , 4,6-trione), tris (diallylamine) -S-triazine, N, N-diallylacrylamide, 1,6-divinyldodecafluorohexane, hexaallylphosphoramide, N, N, N ′, N′-tetra Allyl
- the amount of the crosslinking aid is preferably 0.01 to 10 parts by weight, more preferably 0.01 to 7.0 parts by weight, even more preferably 100 parts by weight of uncrosslinked fluororubber. 0.1 to 5.0 parts by mass.
- the crosslinking aid is less than 0.01 parts by mass, the mechanical properties are deteriorated and the sealing property is inferior, and when it exceeds 10 parts by mass, the heat resistance is inferior and the durability of the oil seal for automobiles tends to be reduced. .
- Polyol crosslinking can be performed by using an uncrosslinked fluororubber capable of polyol crosslinking and a polyhydroxy compound as a crosslinking agent.
- the blending amount of the polyhydroxy compound in the polyol crosslinking system is preferably 0.01 to 8 parts by mass with respect to 100 parts by mass of the uncrosslinked fluororubber capable of polyol crosslinking.
- the polyol crosslinking can be sufficiently advanced. More preferably, it is 0.02 to 5 parts by mass.
- the uncrosslinked fluororubber capable of crosslinking with polyol is not particularly limited as long as it is an uncrosslinked fluororubber having a polyol crosslinkable portion.
- the polyol-crosslinkable site is not particularly limited, and examples thereof include a site having a vinylidene fluoride (VdF) unit.
- Examples of the method for introducing the cross-linked site include a method of copolymerizing a monomer that gives a cross-linked site during polymerization of uncrosslinked fluororubber.
- polyhydroxy compound a polyhydroxy aromatic compound is preferably used from the viewpoint of excellent heat resistance.
- the polyhydroxy aromatic compound is not particularly limited, and examples thereof include 2,2-bis (4-hydroxyphenyl) propane (hereinafter referred to as bisphenol A), 2,2-bis (4-hydroxyphenyl) 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-hydroxyphenyl) butane (hereinafter referred to as bisphenol B), 4,4-bis (4-hydroxyphenyl) valeric acid, , 2-Bis (4-hydroxyphenyl) Trafluorodichloropropane, 4,4′-dihydroxydiphenyl sulfone, 4,4′-dihydroxydip
- polyhydroxy aromatic compounds may be an alkali metal salt, an alkaline earth metal salt or the like, but when the copolymer is coagulated using an acid, it is preferable not to use the metal salt.
- the compounding amount of the polyhydroxy aromatic compound is 0.1 to 15 parts by mass, preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the uncrosslinked fluororubber.
- the cross-linkable composition preferably further contains a cross-linking accelerator.
- a crosslinking accelerator accelerates
- crosslinking accelerator examples include onium compounds.
- onium compounds ammonium compounds such as quaternary ammonium salts, phosphonium compounds such as quaternary phosphonium salts, oxonium compounds, sulfonium compounds, cyclic amines, and 1 It is preferably at least one selected from the group consisting of functional amine compounds, and more preferably at least one selected from the group consisting of quaternary ammonium salts and quaternary phosphonium salts.
- the quaternary ammonium salt is not particularly limited.
- the quaternary phosphonium salt is not particularly limited.
- tetrabutylphosphonium chloride benzyltriphenylphosphonium chloride (hereinafter referred to as BTPPC), benzyltributylphosphonium chloride, benzyltributylphosphonium chloride, tributylallylphosphonium chloride, tributyl.
- BTPPC benzyltriphenylphosphonium chloride
- BTPPC benzyltriphenylphosphonium chloride
- BTPPC benzyltriphenylphosphonium chloride
- crosslinking accelerator a solid solution of a quaternary ammonium salt and bisphenol AF, a solid solution of a quaternary phosphonium salt and bisphenol AF, or a chlorine-free crosslinking accelerator disclosed in JP-A-11-147891 is used. You can also.
- the blending amount of the crosslinking accelerator is preferably 0.01 to 8 parts by mass, more preferably 0.02 to 5 parts by mass with respect to 100 parts by mass of the uncrosslinked fluororubber.
- the crosslinking accelerator is less than 0.01 part by mass, the crosslinking of the uncrosslinked fluororubber does not proceed sufficiently, and the heat resistance and the like of the resulting oil seal for automobiles may be lowered.
- the amount exceeds 8 parts by mass, the moldability of the crosslinkable composition may decrease, the elongation in mechanical properties may decrease, and the sealing property tends to decrease.
- the crosslinkable composition may contain at least one polyfunctional compound.
- the polyfunctional compound is a compound having two or more functional groups having the same or different structures in one molecule.
- the functional groups possessed by the polyfunctional compound include carbonyl groups, carboxyl groups, haloformyl groups, amide groups, olefin groups, amino groups, isocyanate groups, hydroxy groups, epoxy groups, etc., which are generally known to have reactivity. Any group can be used.
- the compound having these functional groups not only has high affinity with uncrosslinked fluororubber, but also reacts with functional groups known to have reactivity possessed by fluororesins, and further improves compatibility. Is also expected.
- the crosslinkable composition containing the uncrosslinked fluororubber and the fluororesin has a volume ratio of uncrosslinked fluororubber and fluororesin (uncrosslinked fluororubber) / (fluororesin) of 60/40 to 95/5. preferable. If the amount of the fluororesin is too small, there is a possibility that sufficient low slidability may not be obtained in the oil seal for automobiles of the present invention. On the other hand, if the amount of the fluororesin is too large, the rubber elasticity may be impaired.
- (Uncrosslinked fluorororubber) / (fluororesin) is 65/35 to 95/5 because both the flexibility resulting from the fluororubber and the low slidability resulting from the fluororesin are good. More preferably, it is 70/30 to 90/10.
- the above-mentioned crosslinkable composition is a usual additive blended in the uncrosslinked fluororubber as necessary, for example, a filler, a processing aid, a plasticizer, a colorant, a stabilizer, an adhesion aid, a release agent, Various additives such as a conductivity imparting agent, a thermal conductivity imparting agent, a surface non-adhesive agent, a flexibility imparting agent, a heat resistance improving agent, and a flame retardant can be blended, and these additives are the effects of the present invention. May be used within a range that does not impair it.
- Molding and cross-linking step This step is a step for producing a cross-linked molded product having substantially the same shape as the elastic member to be produced by forming and cross-linking the mixture obtained in the mixing step.
- the order of molding and crosslinking is not limited, and may be crosslinked after molding, may be molded after crosslinking, or may be molded and crosslinked simultaneously.
- Examples of the molding method include, but are not limited to, a pressure molding method using a mold and the like, and an injection molding method.
- cross-linking method a steam cross-linking method, a normal method in which a cross-linking reaction is started by heating, a radiation cross-linking method, or the like can be adopted, and among them, a cross-linking reaction by heating is preferable.
- a crosslinking reaction by heating is preferable from the viewpoint that the fluororesin smoothly moves to the surface layer of the crosslinkable composition.
- the temperature at which the crosslinking is performed is not less than the crosslinking temperature of the uncrosslinked fluororubber and is preferably less than the melting point of the fluororesin. If the crosslinking is performed at a melting point or higher of the fluororesin, a molded product having a large number of convex portions may not be obtained. In addition, the temperature at which the crosslinking is performed is more preferably 5 ° C. or less lower than the melting point of the fluororesin from the viewpoint that a convex portion made of the fluororesin can be formed on the surface of the crosslinked molded product in the heat treatment step described later. .
- crosslinking conditions is the bridge
- Specific crosslinking conditions that are not limited may be determined as appropriate depending on the type of the crosslinking agent to be used, usually within a temperature range of 150 to 250 ° C. and a crosslinking time of 1 minute to 24 hours.
- the molding and crosslinking methods and conditions may be within the range of known methods and conditions for the molding and crosslinking employed. Further, the molding and the crosslinking may be performed in any order, or may be performed in parallel at the same time.
- a post-treatment step called secondary crosslinking may be performed after the first crosslinking treatment (referred to as primary crosslinking), which will be described in the next heat treatment step (III).
- primary crosslinking the first crosslinking treatment
- the conventional secondary crosslinking step is different from the molding crosslinking step (II) and the heat treatment step (III) of the present invention.
- a metal ring is previously placed in a mold and integrated. Molding may be performed.
- an attachment ring may be arranged in advance in the mold and integrally molded.
- the heat treatment step (III) in the present invention is a treatment step performed to increase the ratio of the fluororesin on the surface of the cross-linked molded product. A temperature below the pyrolysis temperature is employed.
- the heating temperature When the heating temperature is lower than the melting point of the fluororesin, sufficient convex portions cannot be formed on the surface of the crosslinked molded product, and the fluororesin ratio is not sufficiently high.
- the heating temperature In order to avoid thermal decomposition of the fluororubber and the fluororesin, the heating temperature must be lower than the thermal decomposition temperature of the fluororubber or the thermal decomposition temperature of the fluororesin, whichever is lower.
- a preferable heating temperature is a temperature that is higher by 5 ° C. or more than the melting point of the fluororesin from the viewpoint of easily reducing friction in a short time.
- the heating temperature is closely related to the heating time.
- the heating temperature is relatively close to the lower limit, the heating is performed for a relatively long time, and when the heating temperature is relatively close to the upper limit, the heating is relatively short. It is preferable to employ time.
- the heating time may be appropriately set in relation to the heating temperature.
- the fluororubber may be thermally deteriorated. It is practically up to 96 hours excluding the case where is used.
- the heat treatment time is preferably 1 minute to 72 hours, more preferably 1 minute to 48 hours, and further preferably 1 minute to 24 hours from the viewpoint of good productivity. From the standpoint of obtaining an oil seal for use, it is preferably 12 hours or longer.
- the elastic member manufactured through the steps (I) to (III) has a convex portion formed on the entire surface.
- at least the seal lip portion is formed.
- a convex portion is formed on the surface, there may be no convex portion on the surface other than the seal lip portion of the elastic member.
- the conventional secondary cross-linking completely decomposes the cross-linking agent remaining at the end of the primary cross-linking to complete the cross-linking of the fluororubber, thereby improving the mechanical properties and compression set properties of the cross-linked molded product. This is a process to be performed.
- the conventional secondary cross-linking conditions that do not assume the coexistence of fluororesin are the factors for setting the cross-linking conditions in the secondary cross-linking even if the cross-linking conditions coincide with the heating conditions of the heat treatment step.
- the heating condition within the range of the purpose of completing the crosslinking of the uncrosslinked fluororubber (completely decomposing the crosslinking agent) is adopted without considering it as a rubber cross-linked product (rubber It is not an uncrosslinked product), and the conditions for heat softening or melting the fluororesin cannot be derived.
- secondary crosslinking may be performed in order to complete crosslinking of the uncrosslinked fluororubber (to completely decompose the crosslinking agent).
- the remaining crosslinking agent may be decomposed and the crosslinking of the uncrosslinked fluororubber may be completed.
- the crosslinking of the uncrosslinked fluororubber in the heat treatment step (III) is only a secondary effect. It is only an effect.
- the mixture obtained in the mixing step (I) has a structure in which the uncrosslinked fluororubber forms a continuous phase and the fluororesin forms a dispersed phase, or the uncrosslinked fluororubber and the fluororesin form a continuous phase together.
- This structure is presumed to be taken, and by forming such a structure, the cross-linking reaction in the forming cross-linking step (II) can be performed smoothly, and the cross-linked state of the resulting cross-linked product is also uniform.
- the surface transition phenomenon of the fluororesin in the heat treatment step (III) occurs smoothly and a surface with an increased fluororesin ratio can be obtained.
- the heat treatment at the melting point of the fluororesin is particularly excellent in the heat treatment step.
- the state in which the fluororesin ratio in the surface region of the oil seal for automobiles is increased can be verified by chemically analyzing the surface of the elastic member by ESCA or IR.
- atomic groups having a depth of about 10 nm from the surface of the oil seal for automobiles can be identified, but after heat treatment, a peak of binding energy derived from fluororubber (P ESCA 1) and a peak derived from fluororesin (P ESCA 1)
- P ESCA 1 / P ESCA 2 The ratio of P ESCA 2) is smaller than that before heat treatment, that is, the atomic group of the fluororesin is increased.
- IR analysis can identify atomic groups with a depth of about 0.5 to 1.2 ⁇ m from the surface of automobile oil seals. However, after heat treatment, the characteristic absorption due to fluororubber at a depth of 0.5 ⁇ m can be identified.
- the ratio of the peak (P IR0.5 1) to the peak derived from the fluororesin ( PIR0.52 ) ( PIR0.51 / PIR0.52 ) is smaller than that before the heat treatment, that is, the fluororesin There are many atomic groups.
- the characteristic protrusions of the oil seal for automobiles of the present invention are not observed on the surface, so that the inside of the composition as in the present invention.
- the oil seal for automobiles provided with a convex portion on which the specific fluororesin is deposited on the surface is a novel automobile oil seal that has not existed before.
- MFR Melt flow rate of fluororesin [MFR] MFR conforms to ASTM D3307-01 and uses a melt indexer (manufactured by Toyo Seiki Co., Ltd.) to flow out from a nozzle with an inner diameter of 2 mm and a length of 8 mm under a load of 280 ° C. or 327 ° C. and 5 kg per 10 minutes.
- the mass (g / 10 min) was defined as MFR.
- the storage elastic modulus is a value measured at 70 ° C. by dynamic viscoelasticity measurement.
- a sample having a length of 30 mm, a width of 5 mm, and a thickness of 0.25 mm is pulled in a tensile mode using a dynamic viscoelastic device DVA220 manufactured by IT-Measurement Control Co., Ltd.
- the measurement was performed under the conditions of a grip width of 20 mm, a measurement temperature of 25 ° C. to 200 ° C., a temperature increase rate of 2 ° C./min, and a frequency of 1 Hz.
- Tb Tensile strength at break
- FIG. 10 is a schematic diagram of the used oil seal torque tester.
- the shaft 114 is rotatably disposed in the housing 119 via the bearing 113.
- An oil chamber 112 is provided on the distal end side (right side in FIG. 10) of the shaft 114, and an oil seal holding member 117 is attached.
- the measurement oil seal 111 is slidably fixed to the oil seal holding member 117 in a gap between the oil chamber 112 and the oil seal holding member 117.
- a load cell 116 is connected to the oil chamber 112.
- reference numeral 115 denotes an oil seal.
- the oil chamber temperature (oil temperature) is set to a predetermined temperature, and the shaft 114 is rotated at a predetermined rotation by a motor (not shown) to hold the oil seal.
- the member 117 rotates integrally with the shaft 114 and slides relative to the measurement oil seal 111.
- the load of the measurement oil seal 111 is measured by the load cell 116, and the torque is multiplied by the rotation radius. Convert.
- the measurement conditions were that the oil temperature (test temperature) was normal temperature, and the rotation speed of the shaft 114 was 2000 rpm or 5000 rpm.
- FIG. 11 is a schematic diagram of a stroke load measuring and testing machine used in the examples.
- a valve guide 124 is installed on the shaker 123.
- a measurement valve stem seal 121 is slidably fixed to the valve stem shaft 127 at the distal end side of the valve guide 124.
- the valve stem shaft 127 is fixed to the gantry 128 via a load cell 126.
- the measurement valve stem seal 121 reciprocates in close contact with the valve stem shaft 127, and the valve stem shaft 127 at this time is applied.
- the load (stroke load) is measured with the load cell 126.
- the measurement conditions were normal temperature and the reciprocating speed of the shaker 123 was 9.6 cpm or 350 cpm.
- Crosslinking aid MgO magnesium oxide, MA150 manufactured by Kyowa Chemical Industry Co., Ltd.
- Calcium hydroxide CALDIC2000, manufactured by Omi Chemical Co., Ltd.
- Carbon black filler (MT carbon manufactured by Cancarb: N990)
- NEOFLON ETFE Et / TFE copolymer, trade name: EP-610 manufactured by Daikin Industries, Ltd.
- a fluororesin dispersion (B1) and a fluororubber dispersion (A) are mixed in a solution in which 500 ml of water and 4 g of magnesium chloride are mixed in advance in a 1 L mixer, and the solid content is 75/25 (fluororubber / 400 ml of a solution previously mixed so as to be a fluororesin was added, mixed for 5 minutes with a mixer, and co-coagulated. After co-coagulation, the solid content was taken out and dried in a drying oven at 120 ° C. for 24 hours, and then the predetermined composition shown in Table 1 was mixed with an open roll to prepare a crosslinkable composition 1.
- a crosslinkable composition 2 was prepared by the same method as Preparation 1 of the crosslinkable composition except that the fluororesin dispersion (B2) was used instead of the fluororesin dispersion (B1).
- the fluororesin (C) was added so that the volume ratio was 75/25, and kneaded until the material temperature (fluororubber and fluororesin) reached 230 ° C. to prepare a compound. Thereafter, the compound shown in Table 1 was mixed with an open roll to prepare a crosslinkable composition 3.
- Example 1-1 Forming and cross-linking process A metal ring is disposed on the mold of an engine oil seal for automobiles, the cross-linkable composition 1 is introduced, pressurized to 8 MPa, vulcanized at 180 ° C. for 5 minutes, (Shaft diameter 80 mm, outer diameter 98 mm, width 8 mm).
- the crosslinked molded product obtained in the heat treatment step is placed in a heating furnace maintained at 230 ° C. for 24 hours, subjected to heat treatment, and then provided with a ring spring, and an automobile engine oil seal having a structure as shown in FIG. Got.
- a heating furnace maintained at 230 ° C. for 24 hours
- a ring spring for 24 hours
- an automobile engine oil seal having a structure as shown in FIG. Got.
- the number of convex portions, the bottom cross-sectional area, the height, and the area ratio of the regions having the convex portions were measured.
- the rotational torque of the engine oil seal for automobiles was measured. The results are shown in Table 1.
- Example 1-2 Except for using the crosslinkable composition 2 instead of the crosslinkable composition 1, an automobile engine oil seal was obtained in the same manner as in Example 1-1, and various measurements were performed.
- Comparative Example 1 Except for using the crosslinkable composition 3 instead of the crosslinkable composition 1, an automobile engine oil seal was obtained in the same manner as in Example 1-1, and various measurements were performed.
- Example 2-1 Forming and cross-linking process A metal ring is arranged on the mold of the transmission oil seal for automobiles, the cross-linkable composition 1 is introduced, pressurized to 8 MPa, vulcanized at 180 ° C. for 5 minutes, (Shaft diameter 80 mm, outer diameter 98 mm, width 8 mm).
- the crosslinked molded article obtained in the heat treatment step was placed in a heating furnace maintained at 230 ° C. for 24 hours and subjected to a heat treatment to obtain an automobile transmission oil seal having a structure as shown in FIG.
- Using the obtained automobile transmission oil seal the number of convex portions, the bottom cross-sectional area, the height, and the area ratio of the regions having the convex portions were measured.
- the rotational torque of the automobile transmission oil seal was measured. The results are shown in Table 1.
- Example 2-2 Except for using the crosslinkable composition 2 instead of the crosslinkable composition 1, an automobile transmission oil seal was obtained in the same manner as in Example 2-1, and various measurements were performed.
- Comparative Example 2 Except for using the crosslinkable composition 3 instead of the crosslinkable composition 1, an automobile transmission oil seal was obtained in the same manner as in Example 2-1, and various measurements were performed.
- Example 3-1 Forming and cross-linking process A mounting ring is disposed on the mold of the valve stem seal for automobiles, a full compound is introduced, pressurized to 8 MPa, vulcanized at 180 ° C. for 5 minutes, and a cross-linked molded product (lip inner diameter 4. 9 mm, outer diameter 12.8 mm, height 10.1 mm).
- the crosslinked molded product obtained in the heat treatment step was placed in a heating furnace maintained at 230 ° C. for 24 hours and subjected to heat treatment to obtain a valve stem seal for an automobile having a structure as shown in FIG.
- a heating furnace maintained at 230 ° C. for 24 hours and subjected to heat treatment to obtain a valve stem seal for an automobile having a structure as shown in FIG.
- the number of convex portions, the bottom cross-sectional area, the height, and the area ratio of the regions having the convex portions were measured.
- the stroke load of the valve stem seal for automobiles was measured. The results are shown in Table 1.
- Example 3-2 Except for using the crosslinkable composition 2 instead of the crosslinkable composition 1, an automotive valve stem seal was obtained in the same manner as in Example 3-1, and various measurements were performed.
- Comparative Example 3 Except for using the crosslinkable composition 3 instead of the crosslinkable composition 1, an automotive valve stem seal was obtained in the same manner as in Example 3-1, and various measurements were performed.
- the oil seal for automobiles of the present invention is suitable for various oil seals for automobiles because it has an excellent low sliding property as well as a sealing property. Especially, since the rotational torque is small, it is suitable for an engine oil seal for automobiles and a transmission oil seal for automobiles. Moreover, since the stroke load is small, it is also suitable as a valve stem seal for automobiles.
Abstract
Description
特許文献2には、ゴム性のリップ部がシリコーンゴムやフッ素ゴムで構成されたエンジンに使用するオイルシールが開示されている。
特許文献3には、オイルシールのシールリップ部の摺動抵抗の低減を目的として、ゴムの表面にフッ素樹脂の塗膜を形成する方法が提案されている。
特許文献4には、少なくとも主リップ部が設けられたシールリップ部を有する弾性部材を備えた自動車用エンジンオイルシールであって、前記弾性部材は、フッ素ゴム及びフッ素樹脂を含む組成物からなり、かつ、少なくとも前記主リップ部の表面に凸部を有するとともに、前記凸部が実質的に前記組成物に含まれるフッ素樹脂からなり、前記フッ素樹脂は、エチレンに基づく重合単位とテトラフルオロエチレンに基づく重合単位とを含む共重合体であり、前記フッ素ゴムは、ビニリデンフルオライドに基づく重合単位を含む重合体である自動車用エンジンオイルシールが開示されている。
特許文献6には、少なくとも主リップ部が設けられたシールリップ部を有する弾性部材を備えた自動車用トランスミッションオイルシールであって、前記弾性部材は、フッ素ゴム及びフッ素樹脂を含む組成物からなり、かつ、少なくとも前記主リップ部の表面に凸部を有するとともに、前記凸部が実質的に前記組成物に含まれるフッ素樹脂からなり、前記フッ素樹脂は、エチレンに基づく重合単位とテトラフルオロエチレンに基づく重合単位とを含む共重合体であり、前記フッ素ゴムは、ビニリデンフルオライドに基づく重合単位を含む重合体である自動車用トランスミッションオイルシールが開示されている。
特許文献8には、シールリップ部の内周の摺動面にフッ素樹脂膜を有するバルブステムシールが開示されている。
特許文献9には、耐久性及びシール性の向上を目的として、バルブステムオイルシール材の摺動面を含む一部又は全体を熱可塑性フルオロ樹脂、フッ素ゴム及び低分子量含フッ素重合体とする配合からなる潤滑性ゴム組成物で形成することが開示されている。
特許文献10には、バルブステムガイドの末端に配置され、エンジンのバルブステムと摺動自在に密接するシールリップ部を有する弾性部材を備えた自動車用バルブステムシールであって、前記弾性部材は、フッ素ゴム及びフッ素樹脂を含む組成物からなり、かつ、少なくとも前記シールリップ部の表面に凸部を有するとともに、前記凸部が実質的に前記組成物に含まれるフッ素樹脂からなり、前記フッ素樹脂は、エチレンに基づく重合単位とテトラフルオロエチレンに基づく重合単位とを含む共重合体であり、前記フッ素ゴムは、ビニリデンフルオライドに基づく重合単位を含む重合体である自動車用バルブステムシールが開示されている。
従来提案されていたフッ素ゴムやシリコーンゴムを用いた自動車用オイルシールは、アクリルゴムやニトリルゴムを用いた自動車用オイルシールに比べて摺動特性に優れる傾向にある。また、特許文献4、6及び10には、シールリップ部の表面に実質的にフッ素樹脂からなる凸部を有し、該フッ素樹脂がエチレンに基づく重合単位とテトラフルオロエチレンに基づく重合単位とを含む共重合体である自動車用エンジンオイルシール等が開示されており、この凸部を有することにより優れた摺動特性が得られることが記載されている。
しかしながら、上記要求のもと、自動車用オイルシールには、さらなる摺動特性の向上が求められていた。
本発明の自動車用オイルシールは、シールリップ部の表面に上記特定のフッ素樹脂からなる凸部を有するため、クランクシャフト、車軸、エンジンのバルブステム等とシールリップ部とが密接する摺動部において、潤滑油のオイルトラップ効果が促進される。そのため、摺動部において極めて優れた低摺動性を有する自動車用オイルシールとなる。
例えば、自動車用エンジンオイルシール又は自動車用トランスミッションオイルシールとして本発明の自動車用オイルシールを用いる場合、回転トルクを極めて小さくすることができる。また、自動車用バルブステムシールとして用いる場合、ストローク荷重を小さくすることができる。
以下、本発明の自動車用オイルシールの各成分について詳述する。
フッ素ゴムは、通常、主鎖を構成する炭素原子に結合しているフッ素原子を有し、且つゴム弾性を有する非晶質の重合体からなる。上記フッ素ゴムは、1種の重合体からなるものであってもよいし、2種以上の重合体からなるものであってもよい。
CFX=CXOCF2OR1 (1)
(式中、Xは、同一又は異なり、H、F又はCF3を表し、R1は、直鎖又は分岐した、H、Cl、Br及びIからなる群より選択される少なくとも1種の原子を1~2個含んでいてもよい炭素数が1~6のフルオロアルキル基、若しくは、H、Cl、Br及びIからなる群より選択される少なくとも1種の原子を1~2個含んでいてもよい炭素数が5又は6の環状フルオロアルキル基を表す。)で表されるフルオロビニルエーテルなどの含フッ素単量体が挙げられる。これらのなかでも、式(1)で表されるフルオロビニルエーテル、TFE、HFP及びPAVEからなる群より選択される少なくとも1種であることが好ましく、TFE、HFP及びPAVEからなる群より選択される少なくとも1種であることがより好ましい。
CF2=CFO(CF2CFY1O)p-(CF2CF2CF2O)q-Rf (2)
(式中、Y1はF又はCF3を表し、Rfは炭素数1~5のパーフルオロアルキル基を表す。pは0~5の整数を表し、qは0~5の整数を表す。)であることが好ましい。
R2IxBry
(式中、x及びyはそれぞれ0~2の整数であり、かつ1≦x+y≦2を満たすものであり、R2は、炭素数1~16の飽和若しくは不飽和のフルオロ炭化水素基、炭素数1~16の飽和若しくは不飽和のクロロフルオロ炭化水素基、炭素数1~3の炭化水素基、又は、ヨウ素原子若しくは臭素原子で置換されていてもよい炭素数3~10の環状炭化水素基であり、これらは酸素原子を含んでいてもよい)で表される化合物が挙げられる。
ムーニー粘度は、ASTM-D1646に準拠して測定することができる。
測定機器:ALPHA TECHNOLOGIES社製のMV2000E型
ローター回転数:2rpm
測定温度:100℃
フッ素樹脂は、テトラフルオロエチレン(TFE)に基づく重合単位とヘキサフルオロプロピレン(HFP)に基づく重合単位とを含む共重合体(以下、「FEP」ともいう。)である。上記FEPを用いることによって、本発明の自動車用オイルシールは、極めて優れた低摺動性を有する。FEPは、自動車用オイルシールの耐熱性及び耐油性が優れたものとなる点でも好ましい。
融点が低すぎると、架橋成形時にフッ素樹脂が溶融し、所望する形状の自動車用オイルシールが得られないおそれがある。また、シールリップ部の表面に充分な数の凸部を有する自動車用オイルシールが得られないおそれがある。
また、フッ素樹脂の融点が200℃未満である場合には、MFRの測定は280℃で行う。その場合、フッ素樹脂は、280℃におけるMFRが0.3~100g/10分であることが好ましい。上記MFRは、ASTM D3307-1に準拠し、温度280℃、荷重5kgで測定して得られる値である。
フッ素樹脂(B1)及び(B2)は、特定の組成を有するテトラフルオロエチレン(TFE)単位及びヘキサフルオロプロピレン(HFP)単位からなる共重合体である。特定の組成を有するフッ素樹脂(B1)又は(B2)を用いることで、本発明の自動車用オイルシールの低摺動性をより向上させることができ、同時に、自動車用オイルシールの低圧縮永久歪性を向上させることができる。
フッ素樹脂(B1)及び(B2)は、フッ素ゴムとの相溶性に優れる点、自動車用オイルシールの耐熱性が優れたものとなる点からも好ましい。
上記貯蔵弾性率は、動的粘弾性測定により70℃で測定する値である。より具体的には、アイティ-計測制御社製動的粘弾性装置DVA220で長さ30mm、巾5mm、厚み0.5mmのサンプルを引張モード、つかみ幅20mm、測定温度25℃から200℃、昇温速度2℃/min、周波数1Hzの条件で測定する値である。70℃における好ましい貯蔵弾性率(E’)は10~160MPaであり、より好ましい貯蔵弾性率(E’)は20~140MPaであり、更に好ましい貯蔵弾性率(E’)は30~100MPaである。
図1(a)は、シールリップ部が有する凸部の形状を模式的に示す斜視図であり、(b)は(a)の表面に垂直な直線B1と直線B2とを含む平面で凸部11を切断した断面図であり、(c)は(a)の表面と平行な直線C1と直線C2とを含む平面で切断した断面図である。そして、図1(a)~(c)には、シールリップ部の表面の微小領域を模式的に描画している。シールリップ部の表面には、図1(a)~(c)に示すように、例えば、略円錐形状(コーン形状)の凸部11が形成されている。
上記フッ素樹脂はテトラフルオロエチレンに基づく重合単位とヘキサフルオロプロピレンに基づく重合単位とからなる共重合体であり、優れた耐熱性を有する。従って、後述する成形架橋工程や熱処理工程によって分解することがないので、上記シールリップ部に占めるフッ素樹脂の体積比は、後述する架橋性組成物に含まれるフッ素樹脂の体積割合と同一とみなすことができる。
本発明の自動車用オイルシールは、この特徴によりフッ素樹脂の混合割合が小さくても、フッ素ゴムの欠点であった低摺動性が改善され、また、フッ素ゴムの利点である弾性が損なわれることもない。
なお、上記凸部を有する領域の面積比は、シールリップ部において達成されていれば、本発明の効果は十分に奏される。
近年、自動車エンジンの高性能化(高回転化)や低燃費化への要求に伴い、自動車用エンジンオイルシールの摺動特性の向上が望まれており、特に、自動車用エンジンオイルシールには、自動車エンジンの低回転域から高回転域の全域に渡って摺動特性の向上が求められている。
従って、本発明の自動車用オイルシールは、自動車用エンジンオイルシールであることが特に好ましい。
弾性部材22は、クランクシャフト29に当接する径方向断面楔状の主リップ部23及び周方向に沿って内周側に突出する副リップ部25が設けられたシールリップ部、並びに、ハウジング20に密着するはめあい部24を有している。金属環26は弾性部材22に内蔵されており、これにより自動車用エンジンオイルシール21の補強の役割を果たしている。リングスプリング27は、主リップ部23の外周面側に配設されており、主リップ部23はリングスプリング27の付勢力によりクランクシャフト29に当接されることとなる。
この摺動特性に優れるとの効果は、エンジンの回転数を問わず、低回転数から高回転数の全域に渡って奏することができる。これについてもう少し詳しく説明する。
自動車用エンジンオイルシール21の主リップ部23の材質は、上記特定のフッ素樹脂及びフッ素ゴムを含む組成物である。そのため、従来公知の他の自動車用エンジンオイルシールの材質、例えば、ニトリルゴムやアクリルゴム、上記フッ素樹脂を含有しないフッ素ゴム等に比べて摺動特性に優れている。
そのうえで、自動車用エンジンオイルシール21は、上記組成物からなる凸部を有している。
自動車用エンジンオイルシールがクランクシャフトに対して摺動している場合、自動車用エンジンオイルシールとクランクシャフトとの間にはオイルが介在している(油膜が形成されている)ことが知られている。そして、このオイルが両者の間で潤滑剤として機能すると考えられている。即ち、オイルが介在することにより、自動車用エンジンオイルシールは低い摩擦抵抗で摺動することができる。
一方、自動車用エンジンオイルシールは、シール材として機能することが大前提のため、そのシールリップ部はクランクシャフトに隙間無く当接される。そのため、この状態から自動車用エンジンオイルシールとクランクシャフトとの間にオイルが介在するには、シールリップ部が変形し、この変形に追従してオイルがシールリップ部とクランクシャフトとの間に入り込むことが必要となる。ここで、シールリップ部の変形は、クランクシャフトの回転に追従して生じるため、クランクシャフトが高回転数で回転している際にはシールリップ部も変形しやすく、両者の間にオイルが入り込みやすくなる。これに対してクランクシャフトの回転数が低回転数の場合には、高回転数の場合に比べてシールリップ部が変形しにくく、その結果、クランクシャフトとシールリップ部との間にはオイルが介在しにくくなる。
そのため、クランクシャフトの回転数が低回転数の場合は、高回転数の場合に比べて摺動特性が劣る傾向にあり、自動車用エンジンオイルシールにおいては、特に、クランクシャフトの回転数が低回転数の場合における摺動特性の向上が望まれている。
これに対して、本発明の自動車用エンジンオイルシールは、上述したように、シールリップ部の表面に上記特定のフッ素樹脂からなる凸部を有しており、このため、オイルのエンジン外への漏れを防止するという本質的な機能は確保しつつ、微視的にはシールリップ部とクランクシャフトとの間に極微小な空隙を有し、かつ、クランクシャフトの回転に追従して変形しやすい構造を備えていることとなる。
そのため、本発明の自動車用エンジンオイルシールでは、自動車用エンジンオイルシールとクランクシャフトとの間にオイルが介在しやすく、クランクシャフトの回転数を問わず、低回転数から高回転数の全域に渡って摺動特性に優れることとなる。
なお、本発明の自動車用エンジンオイルシールの使用箇所は、クランクシャフトに限定されず、例えば、エンジンがカム軸を備える場合には、カム軸と摺動する自動車用エンジンオイルシールとしても使用することができる。
近年、エンジンの高性能化や低燃費化への要求に伴い、自動車用トランスミッションオイルシールの摺動特性の向上が望まれており、特に、自動車用トランスミッションオイルシールには低速走行時から高速走行時の全域に渡って摺動特性の向上が求められている。
従って、本発明の自動車用オイルシールは、自動車用トランスミッションオイルシールであることが特に好ましい。
弾性部材52は、内周側に車軸59に当接する径方向断面楔状の主リップ部53が設けられたシールリップ部を、外周側にハウジング50に密着するはめあい部54を有している。金属環56は弾性部材52に内蔵されており、これにより自動車用トランスミッションオイルシール51の補強の役割を果たしている。リングスプリング57は、主リップ部53の外周面側に配設されており、主リップ部53はリングスプリング57の付勢力により車軸59に当接されることとなる。
以下、本明細書において、単にシャフトと表記した場合、車軸、メインシャフト及びカウンターシャフトを含むこととする。
この摺動特性に優れるとの効果は、シャフトの回転数を問わず、低回転数から高回転数の全域に渡って奏することができる。これについてもう少し詳しく説明する。
自動車用トランスミッションオイルシール51の主リップ部53の材質は、フッ素樹脂及びフッ素ゴムを含む組成物である。そのため、従来公知の他の自動車用トランスミッションオイルシールの材質、例えば、ニトリルゴムやアクリルゴム、上記特定のフッ素樹脂を含有しないフッ素ゴム等に比べて摺動特性に優れている。
そのうえで、自動車用トランスミッションオイルシール51は、上記組成物からなる凸部を有している。
自動車用トランスミッションオイルシールがシャフトに対して摺動している場合、自動車用トランスミッションオイルシールとシャフトとの間にはオイルが介在している(油膜が形成されている)ことが知られている。そして、このオイルが両者の間で潤滑剤として機能すると考えられている。即ち、オイルが介在することにより、自動車用トランスミッションオイルシールは低い摩擦抵抗で摺動することができる。
一方、自動車用トランスミッションオイルシールは、シール材として機能することが大前提のため、そのシールリップ部はシャフトに隙間無く当接される。そのため、この状態から自動車用トランスミッションオイルシールとシャフトとの間にオイルが介在するには、シールリップ部が変形し、この変形に追従してオイルがシールリップ部とシャフトとの間に入り込むことが必要となる。ここで、シールリップ部の変形は、シャフトの回転に追従して生じるため、シャフトが高回転数で回転している際にはシールリップ部も変形しやすく、両者の間にオイルが入り込みやすくなる。これに対してシャフトの回転数が低回転数の場合には、高回転数の場合に比べてシールリップ部が変形しにくく、その結果、シャフトとシールリップ部との間にはオイルが介在しにくくなる。
そのため、シャフトの回転数が低回転数の場合は、高回転数の場合に比べて摺動特性が劣る傾向にあり、自動車用トランスミッションオイルシールにおいては、特に、シャフトの回転数が低回転数の場合における摺動特性の向上が望まれている。
これに対して、本発明の自動車用トランスミッションオイルシールは、上述したように、シールリップ部の表面に上記特定のフッ素樹脂からなる凸部を有しており、このため、オイルのトランスミッション外への漏れを防止するという本質的な機能は確保しつつ、微視的にはシールリップ部とシャフトとの間に極微小な空隙を有し、かつ、シャフトの回転に追従して変形しやすい構造を備えていることとなる。
そのため、本発明の自動車用トランスミッションオイルシールでは、自動車用トランスミッションオイルシールとシャフトとの間にオイルが介在しやすく、シャフトの回転数を問わず、低回転数から高回転数の全域に渡って摺動特性に優れることとなる。
近年、エンジンの高性能化(高回転化)や低燃費化への要求に伴い、自動車用バルブステムシールの摺動特性の向上が望まれており、自動車用バルブステムシールにはさらなる摺動特性の向上が求められている。また、微小リーク下での耐久性向上のため、耐摩耗性に優れることも要求される。
以下、図面を参照しながら本発明の自動車用バルブステムシールの実施形態について説明する。
弾性部材86は、バルブステム82の外周面に密接するシールリップ部86a、及び、バルブステムガイド83の外周面に密接する静止シール部86bを有している。シールリップ部86aの周囲に設けられたスプリングばね88によって、バルブステム82に対して緊迫力が付与される。
(I)フッ素樹脂と未架橋フッ素ゴムとを混合する工程、
(II)得られた混合物を成形架橋する成形架橋工程、及び
(III)得られた架橋成形品をフッ素樹脂の融点以上の温度に加熱する熱処理工程
を含む方法により、所定の形状の弾性部材を製造し、
更に、必要に応じて、金属環、取付環等を内蔵させたり、リングスプリングを配設することにより製造することができる。
上記架橋性組成物を得る方法は、未架橋フッ素ゴムとフッ素樹脂とを均一に混合できる方法を用いれば特に制限はないが、例えば、未架橋フッ素ゴムとフッ素樹脂の各々を単独で凝析した粉末を粉末混合する方法、未架橋フッ素ゴムとフッ素樹脂を溶融混練する方法、未架橋フッ素ゴムとフッ素樹脂とを共凝析する方法等により得ることができる。中でも、未架橋フッ素ゴムとフッ素樹脂とを溶融混練する方法、又は、未架橋フッ素ゴムとフッ素樹脂とを共凝析する方法が好ましい。
以下に、溶融混練と共凝析について説明する。
溶融混練は、未架橋フッ素ゴムとフッ素樹脂とを、フッ素樹脂の融点より5℃低い温度以上の温度、好ましくはフッ素樹脂の融点以上の温度で行う。加熱温度の上限は、未架橋フッ素ゴム又はフッ素樹脂のいずれか低い方の熱分解温度未満である。
上記混合工程は、未架橋フッ素ゴムとフッ素樹脂とを共凝析して凝析物を得た後、該凝析物を含む架橋性組成物を得るものであることが好ましい。
上記凝析物を含む架橋性組成物を用いることによって、シールリップ部の表面に形成される凸部をより均一かつ微細に形成することができるし、凸部を有する領域の面積比(占有率)をより十分に高くすることもできる。その結果、より優れた低摺動性を有する自動車用オイルシールが得られる。
上記架橋性組成物が、未架橋フッ素ゴムとフッ素樹脂とを共凝析することによって得られる凝析物を含む場合には、未架橋フッ素ゴムとフッ素樹脂とが架橋性組成物中で均一に分散していると予想される。このような架橋性組成物を架橋し、熱処理することにより、低摺動性に優れる本発明の自動車用オイルシールが得られるものと考えられる。
未架橋フッ素ゴムの架橋系によっては架橋剤が必要であるので、未架橋フッ素ゴムとフッ素樹脂とを共凝析して凝析物を得た後、凝析物に架橋剤を添加して架橋性組成物を得てもよい。上記架橋性組成物は、それぞれの架橋系において使用される架橋剤を含むものであってよい。また、上述した各種添加剤等を含むものであってもよい。
通常は、上記凝析物に架橋剤を添加した後、凝析物と架橋剤とを混合する。上記混合は、例えば、ニーダー等を用いた通常の混合方法により、フッ素樹脂の融点未満の温度で混合することができる。
従って、上記架橋剤としては、ポリオール架橋剤、及び、パーオキサイド架橋剤からなる群より選択される少なくとも1種の架橋剤が好ましい。
架橋剤の配合量は、架橋剤の種類等によって適宜選択すればよいが、未架橋フッ素ゴム100質量部に対して0.2~5.0質量部であることが好ましく、より好ましくは0.3~3.0質量部である。
有機過酸化物の配合量は、未架橋フッ素ゴム100質量部に対して0.1~15質量部が好ましく、より好ましくは0.3~5質量部である。
なお、架橋促進剤は、更に、酸化マグネシウム等の受酸剤や、水酸化カルシウム等の架橋助剤と組み合わせて用いてもよい。
これらの官能基を有する化合物は、未架橋フッ素ゴムとの親和性が高いだけではなく、フッ素樹脂が持つ反応性を有することが知られている官能基とも反応し、更に相溶性が向上することも期待される。
この工程は、混合工程で得られた混合物を成形し架橋し、製造する弾性部材と略同形状の架橋成形品を製造する工程である。
成形及び架橋の順序は限定されず、成形した後架橋してもよいし、架橋した後成形してもよいし、成形と架橋とを同時に行ってもよい。
本発明においては、フッ素樹脂が架橋性組成物の表面層へスムーズに移行する点から、加熱による架橋反応が好適である。
また、架橋を行う温度は、後述する熱処理工程において、架橋成形品表面にフッ素樹脂からなる凸部を形成させることができる点から、より好ましくはフッ素樹脂の融点より5℃以上低い温度以下である。また、架橋条件における温度の下限は、未架橋フッ素ゴムの架橋温度である。
限定されない具体的な架橋条件としては、通常、150~250℃の温度範囲、1分間~24時間の架橋時間内で、使用する架橋剤などの種類により適宜決めればよい。
この熱処理工程(III)では、得られた架橋成形品をフッ素樹脂の融点以上の温度に加熱する。熱処理工程(III)を経ることにより、製造する弾性部材の表面に、(主にフッ素樹脂からなる)凸部を形成することができる。
このように加熱時間は加熱温度との関係で適宜設定すればよいが、加熱処理をあまり長時間行うとフッ素ゴムが熱劣化することがあるので、加熱処理時間は、耐熱性に優れたフッ素ゴムを使用する場合を除いて実用上96時間までである。
通常、加熱処理時間は1分間~72時間が好ましく、1分間~48時間がより好ましく、生産性が良好な点から1分間~24時間が更に好ましいが、より優れた低摺動性を有する自動車用オイルシールを得る観点からは、12時間以上であることが好ましい。
核磁気共鳴装置AC300(Bruker-Biospin社製)を用い、測定温度を(ポリマーの融点+50)℃として19F-NMR測定を行い求めた。
示差走査熱量計RDC220(Seiko Instruments社製)を用い、ASTM D-4591に準拠して、昇温速度10℃/分にて熱測定を行い、一度融点ピークの吸熱終了温度+30℃になったら、降温速度-10℃/分で50℃まで降温させ、再度昇温速度10℃/分で吸熱終了温度+30℃まで昇温させ、得られた吸熱曲線のピークから融点を求めた。
MFRは、ASTM D3307-01に準拠し、メルトインデクサー(東洋精機社製)を用いて、280℃又は327℃、5kg荷重下で内径2mm、長さ8mmのノズルから10分間あたりに流出するポリマーの質量(g/10分)をMFRとした。
貯蔵弾性率は、動的粘弾性測定により70℃で測定する値であり、アイティ-計測制御社製動的粘弾性装置DVA220で長さ30mm、巾5mm、厚み0.25mmのサンプルを引張モード、つかみ幅20mm、測定温度25℃から200℃、昇温速度2℃/min、周波数1Hzの条件で測定した。
キュラストメーターII型(JSR(株)製)にて最低トルク(ML)、最高トルク(MH)、誘導時間(T10)及び最適加硫時間(T90)を測定した。
JIS K6251に準じて測定した。
JIS K6251に準じて測定した。
JIS K6251に準じて測定した。
JIS K6253に準じ、デュロメータ タイプAにて測定した(ピーク値)。
JIS K6262に準じて200℃×70h後の圧縮永久歪を測定した。
凸部を有する領域の面積比、凸部の高さ、凸部の底部断面積、凸部の個数等は、キーエンス社製、カラー3Dレーザー顕微鏡(VK-9700)を用い、解析ソフトとして三谷商事株式会社製のWinRooF Ver.6.4.0を用いて算出した。凸部を有する領域の面積比は、凸部の底部断面積を求め、断面積合計の値が、測定全領域面積に占める割合として求められる。凸部の個数は、測定領域中の凸部の個数を1mm2当たりの数に換算したものである。
以下に示す方法で自動車用オイルシールの回転トルクを測定した。
図10は、使用したオイルシールトルク試験機の模式図である。
図10に示すオイルシールトルク試験機110では、シャフト114が軸受113を介してハウジング119内に回転自在に配設されている。シャフト114の先端側(図10中、右側)には、油室112が設けられるとともに、オイルシール保持部材117が取り付けられている。測定用オイルシール111は、油室112とオイルシール保持部材117との間隙にオイルシール保持部材117に対して摺動可能に固定される。また、油室112にはロードセル116が接続されている。なお、図10中、115はオイルシールである。
そして、測定用オイルシール111を取り付けた状態で、油室の温度(油温)を所定の温度に設定し、シャフト114をモータ(図示せず)により所定の回転で回転させると、オイルシール保持部材117がシャフト114と一体的に回転し、かつ、測定用オイルシール111に対して摺動し、このときの測定用オイルシール111の荷重をロードセル116にて測定し、回転半径を乗じてトルク換算する。
ここで、測定条件は、油温(試験温度)を常温とし、シャフト114の回転数を2000rpm又は5000rpmとした。
以下に示す方法で自動車用バルブステムシールのストローク荷重を測定した。
図11は、実施例で使用したストローク荷重測定試験機の模式図である。
図11に示すストローク荷重測定試験機120では、バルブガイド124が加振機123に設置されている。バルブガイド124の先端側には測定用バルブステムシール121がバルブステム軸127に摺動可能に固定される。また、バルブステム軸127は架台128にロードセル126を介して固定されている。
そして、バルブガイド124を加振機123により所定の往復速度で往復運動させると、測定用バルブステムシール121がバルブステム軸127に密接した状態で往復運動し、このときのバルブステム軸127にかかる荷重(ストローク荷重)をロードセル126で測定する。
ここで、測定条件は、常温で、加振機123の往復速度を9.6cpm又は350cpmとした。
ビスフェノールAF 特級試薬(和光純薬工業(株)製)
BTPPC 特級試薬(和光純薬工業(株)製)
MgO(酸化マグネシウム、協和化学工業(株)製 MA150)
水酸化カルシウム(近江化学工業(株)製 CALDIC2000)
カーボンブラック(Cancarb社製のMTカーボン:N990)
ダイキン工業(株)製 2元フッ素ゴム水性ディスパージョン(固形分濃度26質量%、フッ素ゴム:VdF/HFP共重合体、VdF/HFP=78/22(モル比))(フッ素ゴムディスパージョン(A))
ダイキン工業(株)製 ネオフロンFEP(TFE/HFP共重合体)水性ディスパージョン(固形分濃度21質量%、MFR31.7g/10min(327℃、5kg測定)、融点215℃、貯蔵弾性率(E’)167MPa、TFE/HFP=87.9/12.1(モル比))(フッ素樹脂ディスパージョン(B1))
ダイキン工業(株)製 ネオフロンFEP(TFE/HFP共重合体)水性ディスパージョン(固形分濃度20.1質量%、MFR7.5g/10min(280℃、5kg測定)、融点186℃、貯蔵弾性率(E’)59MPa、TFE/HFP=84.7/15.3(モル比))(フッ素樹脂ディスパージョン(B2))
ダイキン工業(株)製 ネオフロンETFE(Et/TFE共重合体、商品名:EP-610)
容量1Lのミキサー内に、水500mlと塩化マグネシウム4gをあらかじめ混合した溶液にフッ素樹脂ディスパージョン(B1)とフッ素ゴムディスパージョン(A)とを、固形分が体積比で75/25(フッ素ゴム/フッ素樹脂)となるようにあらかじめ混合した溶液400mlを投入し、ミキサーにて5分間混合し、共凝析した。
共凝析後、固形分を取り出し、120℃×24時間乾燥炉で乾燥させた後、オープンロールにて表1に示す所定の配合物を混合して、架橋性組成物1を調製した。
フッ素樹脂ディスパージョン(B1)の代わりにフッ素樹脂ディスパージョン(B2)を用いた以外は、架橋性組成物の調製1と同じ方法で架橋性組成物2を調製した。
容量1Lのミキサー内に、水500mlと塩化マグネシウム4gをあらかじめ混合した溶液にフッ素ゴムディスパージョン(A)400mlを投入し、ミキサーにて5分間混合し、凝析した。凝析後、固形分を取り出し、120℃×24時間乾燥炉で乾燥させた後、内容量3Lの加圧ニーダーに体積充填率が85%になるように凝析後のフッ素ゴム(A)とフッ素樹脂(C)を体積比で75/25となるように投入し、材料温度(フッ素ゴムとフッ素樹脂)が230℃になるまで練り、コンパウンドを調製した。その後コンパウンドをオープンロールにて表1に示す所定の配合物を混合して、架橋性組成物3を調製した。
成形架橋工程
自動車用エンジンオイルシールの金型に金属環を配設し、架橋性組成物1を投入して、8MPaに加圧して、180℃で5分間加硫させて、架橋成形品(適応軸径80mm、外径98mm、幅8mm)を得た。
得られた架橋成形品を230℃に維持された加熱炉中に24時間入れ、加熱処理をした後、リングスプリングを配設し、図4に示すような構造を有する自動車用エンジンオイルシールを得た。得られた自動車用エンジンオイルシールを用いて、凸部の数、底部断面積、高さ、凸部を有する領域の面積比を測定した。また、自動車用エンジンオイルシールの回転トルクを測定した。結果を表1に示す。
架橋性組成物1の代わりに架橋性組成物2を用いたこと以外は、実施例1-1と同じ方法で自動車用エンジンオイルシールを得て、各種測定を行った。
架橋性組成物1の代わりに架橋性組成物3を用いたこと以外は、実施例1-1と同じ方法で自動車用エンジンオイルシールを得て、各種測定を行った。
成形架橋工程
自動車用トランスミッションオイルシールの金型に金属環を配設し、架橋性組成物1を投入して、8MPaに加圧して、180℃で5分間加硫させて、架橋成形品(適応軸径80mm、外径98mm、幅8mm)を得た。
得られた架橋成形品を230℃に維持された加熱炉中に24時間入れ、加熱処理をし、図7に示すような構造を有する自動車用トランスミッションオイルシールを得た。得られた自動車用トランスミッションオイルシールを用いて、凸部の数、底部断面積、高さ、凸部を有する領域の面積比を測定した。また、自動車用トランスミッションオイルシールの回転トルクを測定した。結果を表1に示す。
架橋性組成物1の代わりに架橋性組成物2を用いたこと以外は、実施例2-1と同じ方法で自動車用トランスミッションオイルシールを得て、各種測定を行った。
架橋性組成物1の代わりに架橋性組成物3を用いたこと以外は、実施例2-1と同じ方法で自動車用トランスミッションオイルシールを得て、各種測定を行った。
成形架橋工程
自動車用バルブステムシールの金型に取付環を配設し、フルコンパウンドを投入して、8MPaに加圧して、180℃で5分間加硫させて、架橋成形品(リップ内径4.9mm、外径12.8mm、高さ10.1mm)を得た。
得られた架橋成形品を230℃に維持された加熱炉中に24時間入れ、加熱処理をし、図8に示すような構造を有する自動車用バルブステムシールを得た。
得られた自動車用バルブステムシールを用いて、凸部の数、底部断面積、高さ、凸部を有する領域の面積比を測定した。また、自動車用バルブステムシールのストローク荷重を測定した。結果を表1に示す。
架橋性組成物1の代わりに架橋性組成物2を用いたこと以外は、実施例3-1と同じ方法で自動車用バルブステムシールを得て、各種測定を行った。
架橋性組成物1の代わりに架橋性組成物3を用いたこと以外は、実施例3-1と同じ方法で自動車用バルブステムシールを得て、各種測定を行った。
11:凸部
20、50、119:ハウジング
21:自動車用エンジンオイルシール
22、52、86:弾性部材
23、53:主リップ部
24、54:はめあい部
25:副リップ部
26、56:金属環
27、57:リングスプリング
29:クランクシャフト
30:エンジン
32:クランクプーリー
33:コンロッド
34:ピストン
35:バルブ
51:自動車用トランスミッションオイルシール
59:車軸
60:トランスミッション
62:メインシャフト(入力シャフト)
63:カウンターシャフト(出力シャフト)
81:自動車用バルブステムシール
82:バルブステム
83:バルブステムガイド
86a:シールリップ部
86b:静止シール部
87:取付環
88:スプリングばね
95:エンジンバルブ
110:オイルシールトルク試験機
111:測定用オイルシール
112:油室
113:軸受
114:シャフト
115:オイルシール
116、126:ロードセル
117:オイルシール保持部材
120:ストローク荷重測定試験機
121:測定用バルブステムシール
123:加振機
124:バルブガイド
127:バルブステム軸
128:架台
Claims (8)
- シールリップ部を有する弾性部材を備えた自動車用オイルシールであって、
前記弾性部材は、フッ素ゴム及びフッ素樹脂を含む組成物からなり、かつ、少なくとも前記シールリップ部の表面に凸部を有するとともに、前記凸部が実質的に前記組成物に含まれるフッ素樹脂からなり、
前記フッ素樹脂は、テトラフルオロエチレンに基づく重合単位とヘキサフルオロプロピレンに基づく重合単位とを含む共重合体である
ことを特徴とする自動車用オイルシール。 - フッ素ゴムは、
ビニリデンフルオライドに基づく重合単位と、
テトラフルオロエチレン、ヘキサフルオロプロピレン、及び、パーフルオロ(アルキルビニルエーテル)からなる群より選択される少なくとも1種の単量体に基づく重合単位と、
を含む共重合体である請求項1記載の自動車用オイルシール。 - シールリップ部に占めるフッ素樹脂の体積比が0.05~0.45であり、
シールリップ部の表面に占める凸部を有する領域の面積比が0.06以上であり、
シールリップ部の表面に占める凸部を有する領域の面積比が、シールリップ部に占めるフッ素樹脂の体積比の1.2倍以上である
請求項1又は2記載の自動車用オイルシール。 - 凸部は、高さが0.1~30.0μmである
請求項1、2又は3記載の自動車用オイルシール。 - 凸部は、底部断面積が0.1~2000μm2である
請求項1、2、3又は4記載の自動車用オイルシール。 - 自動車用エンジンオイルシールであって、
弾性部材は、シールリップ部に少なくとも主リップ部が設けられ、少なくとも前記主リップ部の表面に凸部を有する
請求項1、2、3、4又は5記載の自動車用オイルシール。 - 自動車用トランスミッションオイルシールであって、
弾性部材は、シールリップ部に少なくとも主リップ部が設けられ、少なくとも前記主リップ部の表面に凸部を有する
請求項1、2、3、4又は5記載の自動車用オイルシール。 - エンジンのバルブステムガイドの末端に配置される自動車用バルブステムシールであって、
シールリップ部は、エンジンのバルブステムと摺動自在に密接するものである
請求項1、2、3、4又は5記載の自動車用オイルシール。
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JP2013555222A JP5786967B2 (ja) | 2012-01-23 | 2013-01-16 | 自動車用オイルシール |
KR1020147021778A KR20140110046A (ko) | 2012-01-23 | 2013-01-16 | 자동차용 오일 시일 |
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US10377932B2 (en) | 2015-08-18 | 2019-08-13 | Jtekt Corporation | Sealing rubber composition and seal member |
Also Published As
Publication number | Publication date |
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CN104067036B (zh) | 2016-09-28 |
US20150014941A1 (en) | 2015-01-15 |
JPWO2013111643A1 (ja) | 2015-05-11 |
EP2808585A4 (en) | 2015-10-07 |
CN104067036A (zh) | 2014-09-24 |
EP2808585A1 (en) | 2014-12-03 |
JP5786967B2 (ja) | 2015-09-30 |
KR20140110046A (ko) | 2014-09-16 |
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