WO2003062681A1

WO2003062681A1 - Seal for rotating shaft and method for manufacture thereof

Info

Publication number: WO2003062681A1
Application number: PCT/JP2002/013758
Authority: WO
Inventors: Hitoshi Shimoura; Masanori Fujii; Hiromi Obata; Takeshi Baba
Original assignee: Mitsubishi Cable Industries, Ltd.
Priority date: 2001-12-28
Filing date: 2002-12-27
Publication date: 2003-07-31

Abstract

A seal for a rotating shaft wherein a sealing element containing PTFE as a main component is housed in a metal case, characterized in that the sealing element is adhered to the metal case via a layer of a fluororesin having a hydroxyl group in its molecule so as to be integrated with the metal case; and a method for manufacturing the seal, wherein a laminate comprised of the sealing element, the metal case and, sandwiched between them, the fluororesin is subjected to heating and compression, and then the laminate is cooled under the application of a load. The seal has the sealing element fixed firmly to the metal case, and thus is extremely low in possibility of the occurrence of a critical path and highly reliable, without the use of a metal part or a rubbery elastomer specially made therefor and with a simple constitution. Further, the adhesion between a sealing element and a metal case has high durability also against the change of temperature, which results in the retention of good sealing performance capabilities against the temperature change in the circumstance for use. The manufacturing method, which is simple, allows the significant reduction of the time required for the manufacture relative to that in the case of a conventional seal of cramp type, does not need a heating operation for a long time which is required in the case wherein use is made of an epoxy resin based adhesive known as a heat-resistant adhesive usable also for a metal, and is free form complexities associated with the management of work conditions and facilities for application of an adhesive, which lead to the commercial production of a seal with good efficiency.

Description

Specification

Rotary shaft seal and method of manufacturing the same

Technical field

The present invention relates to a rotary shaft seal and a method for manufacturing the same, and more particularly, to a rotary shaft seal using a seal element mainly containing polytetrafluoroethylene and a method for manufacturing the same.

Background art

Conventionally, a seal used for an automobile engine shaft has been a combination of a rubber seal element and a metal case (annular metal fittings). However, in recent years, high-speed rotation of the engine shaft has been required in order to further increase the durability of the seal due to an increase in the operating temperature of the shaft. Therefore, polytetraflus having high heat resistance and low frictional resistance as a seal element have been developed. Polyethylene (hereinafter, also referred to as PTFE) is being used. However, the sealing element made of rubber (fluororubber) can be integrated with the metal case by molding rubber (fluororubber) so as to cover the metal case, but the seal element made of PTFE uses PTFE as the metal. Since it cannot be molded so as to cover the case, in general, a fixing bracket is used separately from the metal case, and a sealing element is sandwiched between the metal case and the fixing bracket. It is fixed by bending (force crimping). At this time, the rubber elastic body is sandwiched together with the seal element made of PTFE to prevent the movement and rotation of the seal element. However, since the fixing of the seal element is due to the mechanical compression force, it is difficult to say that the fixing force is sufficiently high. Particularly, when the assembling accuracy is poor, the deformation of the metal parts and the seal element, the position of the rubber elastic body The seal element moves due to misalignment, swelling, etc., creating an unnecessary gap, and the critical path through which liquid and gas pass through from the part other than the contact part (seal part) of the seal lip with the rotating shaft. May occur. In addition, the need for metal parts and rubber elastic bodies to sandwich the sealing element in addition to the metal case requires a large number of parts, requires time-consuming assembly (manufacturing time is long), and manages manufacturing equipment. Complex and low productivity.

Therefore, the present inventors have developed a PTFE seal element using an epoxy resin-based adhesive. We tried to fix the adhesive to the metal case. However, compared to other resins, fluororesins such as PTFE have low surface free energy, are inert on the surface, and require a sodium treatment on the surface of the sealing element to obtain good adhesion. After immersion in a sodium solution, exposure to air to introduce hydroxyl groups, etc.) or plasma treatment to modify the surface of the seal element is required. Since these surface treatment methods use special gases and solvents, special equipment and working environments are indispensable, and equipment and management costs increase. Epoxy resin adhesives are liquid at room temperature, and the work conditions for applying the adhesive to the metal case (ambient temperature, discharge pressure, time, measurement, prevention of dripping / clogging), etc., are controlled. There is a problem of complexity. Therefore, to apply it to mass production (industrial production), the number of processes is large, the equipment is complicated, work management in each process is not easy, and the production time is long. I can't say. In addition, the rotary shaft seal obtained by such a method has a metal case and a seal element adhered to each other with a certain high adhesive strength. However, the heat seal between the epoxy resin adhesive and the polytetrafluoroethylene is not sufficient. Due to the difference in the expansion coefficient, the adhesive force between the metal case and the sealing element is reduced in use in a high-temperature environment, and there is a possibility that sealing fluid leaks from portions other than the shaft seal portion. In view of the circumstances described above, the present invention has a simple configuration without using a dedicated metal part or rubber elastic body, and has a seal element mainly composed of PTFE firmly fixed to a metal case. It is an object of the present invention to provide a highly reliable rotating shaft seal in which a critical path is extremely unlikely to occur.

In addition, with a small number of processes, easy management of each process, and simple manufacturing equipment, a rotary shaft seal with a PTFE-based seal element firmly fixed to a metal case can be manufactured efficiently and in a short time. O to provide a method of manufacturing a rotary shaft seal o

Disclosure of the invention

In order to achieve the above object, the present invention has the following features.

That is, the present invention

(1) A rotary shaft seal having a structure in which a metal case contains a seal element mainly composed of polytetrafluoroethylene, A rotary shaft seal, wherein a seal element mainly composed of polytetrafluoroethylene is adhered to and integrated with a metal case through a layer of a fluororesin having a hydroxyl group in a molecule;

(2) An annular shape in which a metal case protrudes a flange portion from one axial end of the cylindrical peripheral wall portion toward the internal space, and forms a circular through-hole through which the rotation shaft passes. Metal case,

The seal element has a ring shape, and is bonded to a flange of the annular metal case via a layer of a fluororesin having a hydroxyl group in a molecule.

The fluororesin layer having a hydroxyl group in the molecule is provided so that the terminal portion on the rotating shaft side does not protrude into the through hole from the terminal portion on the rotating shaft side of the flange portion. The rotary shaft seal described in (1) above,

(3) The rotary shaft seal according to the above (2), wherein a layer of a fluororesin having a hydroxyl group in the molecule is provided so as to cover an area of 20 to 100% of the surface to be bonded of the flange portion. '

(4) The above-mentioned (2), wherein a fluororesin having a hydroxyl group in a molecule is not present in a ring-shaped region having a width of 0.1 m or more around a circular through-hole on a surface to be bonded of a flange portion. ) Rotary shaft seal

(5) The rotary shaft seal according to any one of (1) to (4), wherein the thickness of the layer of the fluororesin having a hydroxyl group in the molecule is 5 to 1001m.

(6) A method for manufacturing a rotary shaft seal in which a seal element mainly composed of polytetrafluoroethylene is integrated with a metal case, comprising:-a seal element mainly composed of polytetrafluoroethylene and a metal; A fluororesin having a hydroxyl group in the molecule and having a melting point lower than the melting point of polytetrafluoroethylene constituting the sealing element is sandwiched between the case and the obtained stack. After heating and compressing, the stack is cooled under a load, and the fluororesin having a hydroxyl group in the molecule is melted and solidified.

(7) The method for producing a rotary shaft seal according to the above (6), wherein the fluororesin having a hydroxyl group in a molecule is a molded product molded into a film.

(8) The melting point of the fluororesin having a hydroxyl group in the molecule and the poly (6) The method for producing a self-mounted rotary shaft seal, wherein the difference from the melting point of tetrafluoroethylene is 10 ° C. or more.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram schematically illustrating a rotary shaft seal according to one embodiment of the present invention, and is a radial cross-sectional view of a metal case in a state where the metal case is mounted between a housing and a rotary shaft.

FIG. 2 is a simplified view of a rotary shaft seal according to one embodiment of the present invention. FIG. 2 is a radial cross-sectional view of the metal case before being mounted between the housing and the rotary shaft. (A)) and a plan view (Fig. (B)).

FIG. 3 is a view for explaining an operation of sandwiching a fluororesin having a hydroxyl group in a molecule between a metal case and a seal element in the method of manufacturing a rotary shaft seal according to the present invention, and FIG. The arrangement of the seal element and the fluorine resin (film) having a hydroxyl group in the molecule is shown in Fig. (B). The metal case, the seal element and the fluorine resin (hydroxyl) having the hydroxyl group in the molecule after the work are shown in Fig. (B). Shows the arrangement state of.

FIG. 4 is a cross-sectional view of a step of heating and compressing a stack in which a fluorine resin having a hydroxyl group in a molecule is sandwiched between a metal case and a seal element in the method of manufacturing a rotary shaft seal according to the present invention.

FIG. 5 is a cross-sectional view schematically showing a jig for measuring a shearing-off torque.

FIG. 6 is a cross-sectional view schematically showing a conventional clamp type rotary shaft seal.

The symbols in the drawings will be briefly described. 1 in FIGS. 1 to 3 is a rotating shaft seal, 2 is a metal case, 3 is a sealing element, and 10 in FIGS. 1 and 2 is A layer of a fluororesin having a hydroxyl group is shown, and 1OA in FIG. 3 indicates a circular ring-shaped film made of a fluororesin having a hydroxyl group in a molecule. Also, in FIGS. 3 and 4, reference numeral 20 denotes a stack, 15 A and 15 B in FIG. 4 denote press plates, 17 denotes a thermostat, and 21 denotes a compression jig.

Detailed description of the invention

In the rotating shaft seal of the present invention, a metal case accommodates a sealing element containing polytetrafluoroethylene (PTFE) as a main component, and the sealing element is interposed through a layer of a fluororesin having a hydroxyl group in a molecule. It is bonded and integrated into the case, engine shaft, In order to prevent leakage of fluid sealed around the rotating shaft from one side in the longitudinal direction of the rotating shaft to the other side in air conditioner compressors, super jars, evening jars, etc. It is used by inserting it into a rotating shaft.

The seal element containing PTFE as the main component used in the present invention has excellent mechanical properties even under the high temperature operating environment of the rotating shaft due to the excellent heat resistance, oil resistance, chemical resistance and low friction of PTFE. (Strength and elongation) are hardly deteriorated and the frictional resistance is small.

In the rotary shaft seal of the present invention, a layer of a fluororesin having a hydroxyl group in a molecule interposed between a seal element mainly composed of PTFE and a metal case is formed on both the seal element and the metal case. It fuses with high adhesive strength, and as a result, the sealing element mainly composed of PTFE is firmly bonded and integrated with the metal case. Therefore, not only at room temperature (25 ° C) but also at high temperature (150 ° C or more, specifically 150-180 ° C) or extremely low temperature (-40 ° C or less, specifically -40-170 ° C). (° C), the sealing element mainly composed of PTFE is firmly fixed to the metal varnish, and has sufficient resistance to rotational torque caused by contact with the axis of the sealing element. Therefore, peeling of the seal element is unlikely to occur, and the occurrence of a critical path is extremely unlikely to occur. In addition, since the seal element and the metal case are integrated by bonding, the metal case is bent (forced) using the conventional fixing bracket and rubber elastic body, thereby forming the seal element into the metal case. The manufacturing operation is extremely simple compared to a rotating shaft seal that is mechanically fixed to the shaft (hereinafter, also referred to as a “clamp-type rotating shaft seal”). The “sea element mainly composed of polytetrafluoroethylene (PTFE)” used in the present invention is a seal element formed by molding PTFE alone, or a composition obtained by combining PTFE with a filler or the like. Means a sealing element formed from an object. In addition, “polytetrafluoroethylene (PTFE)” used for the seal element includes modified PTFE (polybutafluoroethylene) obtained by copolymerizing a small amount of perfluoroalkylvinyl ether with polytetrafluoroethylene. Content of 99.0 mol% or more). Examples of perfluoroalkyl vinyl ethers in such modified PTF E include perfluoromethyl, no ^ -fluoroethyl, perfluoropropyl, perfluorobutyl, and perfluoropentene. Chill, perfluorohexyl and the like.

The “PTFE-based sealing element” used in the present invention includes, for example, PT FE processed into a desired shape, or PTFE, a filler, and other additives to be combined as necessary. A mixture obtained by mixing with a known mixing device such as Henschel mixer and processed into a desired shape is used. The processing method is not particularly limited, but a method through compression molding, sintering, and cutting is preferable. A commercially available sealing element can also be used.

Examples of the filler to be mixed with PTFE include inorganic fibers, solid lubricants, hard copper alloy powder, and the like.

Inorganic fibers are effective for improving the abrasion resistance of the sealing element.For example, glass fibers such as soda glass, alkali-free glass and silica glass, ceramic fibers such as rock wool, steel, iron, aluminum, nickel, copper, etc. Metal fibers, whisks such as potassium titanate, carbon fibers, and carbon graphite fibers. Of these, glass fibers such as non-alkali glass are preferred. The inorganic fibers preferably have a single fiber tensile strength of 20 OkgfZmm ² or more, and more preferably have a single fiber tensile strength of 30 OkgfZmm ² or more. Further, those having an average fiber diameter of 50 m or less are preferable, and those having an average fiber diameter of 1 Ozm or less are more preferable. The average length of the inorganic fiber is preferably 10 m to 1000 m, and 50 m! ~ 15 O zm is particularly preferred. Further, the aspect ratio is preferably from 1 to 80, and particularly preferably from 5 to 50.

The solid lubricant can be used without limitation as long as it is a compound capable of imparting a known lubricating property. Among them, stone, mica, stone, stone, zinc white, molybdenum-based compounds and the like are preferable, and molybdenum is particularly preferable. It is a system compound.

Hard copper alloy powder is effective for improving the creep property (load deformation resistance) of the seal element, and examples thereof include powders of various copper alloys such as bronze, brass, phosphor bronze, nickel silver, and lead bronze. Among them, bronze powder is preferable.

The above-mentioned hard copper alloy powder and solid lubricant are both used in the form of fine powder or fine powder. It is particularly preferable that the particles pass 100% through the same sieve 200 mesh.

Additives that can be added to PTFE as needed include, for example, heat-resistant resin powders and pigments. Examples of the heat-resistant resin powder include powders such as polyphenylene sulfide (PPS), polyimide resin (P1), and aromatic polyester resin (LCP). Examples of the pigment include bengara, conoretable, titanium oxide, and the like.

The present inventors have found that the use of a sealing element composed of a composition in which a filler is mixed with PTFE enables higher adhesion to a fluororesin having a hydroxyl group in the molecule to be obtained. This is probably because the sealing element containing the filler has minute irregularities on its surface, and the fluorine resin having a hydroxyl group enters the minute irregularities, thereby providing an anchor effect. . In particular, based on 100 parts by weight of PTFE, 3 to 30 parts by weight of inorganic fiber, 2 to 5 parts by weight of solid lubricant, or 1 to 50 parts by weight of hard copper alloy powder A higher adhesive strength can be obtained by using a sealing element composed of the composition or a composition containing any two or three of these fillers in the above-described predetermined amount. . Of these, the combination of inorganic fibers and solid lubricant is the most preferred embodiment.

In the present invention, the thickness of the seal element containing PTFE as a main component is not particularly limited, but is generally about 0.2 to 1.5 mm, preferably about 0.4 to 1.2 mm.

The fluororesin having a hydroxyl group in the molecule used in the present invention is a fluororesin having no hydroxyl group in the molecule known per se, and one or more kinds of a fluorine-containing ethylene monomer having a hydroxyl group. Are further copolymerized.

Examples of the fluorine-containing ethylene monomer having a hydroxyl group include compounds represented by the following general formula (I).

Formula (D CX ^ CX ¹ -R _f — CH ₂ OH

(Wherein X and X ¹ may be the same or different and each represents a hydrogen atom or a fluorine atom, R _f is a divalent alkylene group having 1 to 40 carbon atoms, and a fluorine-containing 1 to 40 carbon atoms. An alkoxyalkylene group, a fluorine-containing alkylene group having an ether bond having 1 to 40 carbon atoms. Or a fluorine-containing oxyalkylene group containing an ether bond having 1 to 40 carbon atoms. Specific examples of the compound represented by the general formula (I) include the following compounds a to p. a: CF ₂ = CFOCF ₂ CF ₂ CH ₂ OH, b: CF ₂ = CFO (CF ₂ ) ₃ CH ₂ OH, c: CF ₂ = CFOCF ₂ CFOCF ₂ CF ₂ CH ₂ OH, d: CF ₂ = CFCF ₂ CH ₂ OH,

CF ₃ e: CF ₂ = CFCF ₂ CF ₂ CH ₂ OH, f: CF ₂ = CFCF ₂ OCF ₂ CF ₂ CF ₂ CH ₂ OH,

g: CF ₂ = CFCF ₂ OCF ₂ CFCH ₂ OH ヽ h: CH ₂ = CFCF ₂ CF ₂ CH ₂ CH ₂ OH ヽ

CF ₃ i: CH ₂ = CFCF ₂ CF ₂ CH ₂ OH, j: CH ₂ = CF (CF ₂ ) ₄ CH ₂ CH ₂ OH ヽ k: CH ₂ = CFCF ₂ OCFCH ₂ OH _> l: CH ₂ = CFCF ₂ OCFCF ₂ OCFCH ₂ OH,

CF ₃ CF ₃ CF ₃ m: CH ₂ = CHCF ₂ CF ₂ CH ₂ CH ₂ OH _s n: CH ₂ = CH (CF ₂ ) ₄ CH ₂ CH ₂ CH ₂ 0¾

o: CH ₂ = CH (CF ₂ ) ₆ CH ₂ CH ₂ OH, p: CH ₂ = CHCH ₂ COH

Three

Among them, compound 1 (1,1-, 9,9-tetrahydro-1,2,5-bistrifluoromethyl-3,6-dioxal 8-nonenol) is particularly preferred.

Examples of the fluororesin having no hydroxyl group in the molecule include tetrafluoroethylene, perfluoroalkyl vinyl ether, black trifluoroethylene, and vinylidyl fluoride. Polymers having at least one fluorine-containing ethylene monomer selected from the group consisting of denene and hexafluoropropylene as a constitutional unit (homopolymers, copolymers), or the at least one Copolymers containing a fluorine-containing ethylene monomer and ethylene as constituent units are exemplified.

The fluororesin having a hydroxyl group in the molecule includes a fluorine-containing ethylene monomer having a hydroxyl group and a fluorine-containing ethylene monomer having no hydroxyl group (a conventionally known fluorine-containing monomer having no hydroxyl group in the molecule). And a monomer constituting the resin) by a known polymerization method. The polymerization mechanism in such copolymerization is preferably radical polymerization. As the radical polymerization initiator, a known radical polymerization initiator that generates radicals by heat, light or ionizing radiation can be used. The polymerization method is not particularly limited, and solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization and the like can be used without limitation. Also, the copolymer to be produced

The molecular weight of the (fluorine resin having a hydroxyl group in the molecule) is controlled by the concentration of the monomer, the concentration of the polymerization initiator, the concentration of the chain transfer agent, the temperature, etc., and the resulting copolymer (having a hydroxyl group in the molecule) The composition of (fluororesin) can be controlled by the composition of the charged monomers. As the fluororesin having a hydroxyl group in the molecule in the present invention, the fluororesin having a hydroxyl group in the molecule described in the publication of International Publication No.WO 97/21779 can be suitably used, and among them, Tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer (PFA) obtained by further copolymerizing a fluorine-containing ethylene-based monomer having a hydroxyl group, tetrafluoroethylene-hexafluoro Propylene copolymer (FEP) is obtained by further copolymerizing a fluorinated ethylenic monomer having a hydroxyl group, and ethylene-tetrafluoroethylene copolymer (ETFE) is obtained by further copolymerizing a fluorinated ethylene monomer having a hydroxyl group. Copolymers and the like are preferable, and those obtained by further copolymerizing PFA with a fluorine-containing ethylene monomer having a hydroxyl group (hereinafter referred to as “hydroxyl-containing PFA”) Is particularly preferred.

In the fluororesin having a hydroxyl group in the molecule used in the present invention, the copolymerization amount of the fluorine-containing ethylene monomer having a hydroxyl group is usually from 0.05 to 5% per the whole polymer (resin).

It is 30 mol%, preferably 0.1 to 10 mol%. If the copolymerization amount of the fluorinated ethylene monomer is less than 0.05 mol%, the amount of the sealant and the metal case may be reduced. If it exceeds 30 mol%, its heat resistance will decrease, and its melting and solidification will cause coloring, foaming, etc., and its adhesion will decrease. In addition, as described later, when a molded product formed into a film is used, coloring, foaming, decomposition, and the like occur during the molding, and the adhesiveness of the molded product (film) tends to decrease. Not preferred.

In the present invention, the fluororesin having a hydroxyl group in the molecule may be used as a composition in which various additives such as a filler and a pigment are blended as long as the adhesiveness, heat resistance and the like are not impaired.

1 and 2 are simplified views of a specific example of a rotary shaft seal according to the present invention. FIG. 1 is a radial cross-sectional view of a metal case, in which a housing and a rotary shaft are actually connected. It shows a radial portion with respect to the shaft in a state where the seal element is mounted and pressed against the seal element. The figure shows a radial portion on one side contacting the shaft of the seal, and the other radial portion contacting the shaft (not shown) has the same configuration. Fig. 2 shows the rotating shaft seal before it is mounted between the housing and the rotating shaft. Fig. (A) is a radial cross section of the metal case, and Fig. (B) is a plan view of the metal case. It is.

In the rotary shaft seal 1, a layer 10 of a fluororesin having a hydroxyl group in the molecule is fused to the metal case 2 and the circular ring-shaped seal element 3, whereby the seal element 3 and the metal case 2 are fused. Are firmly adhered to each other. The metal case 2 has a cylindrical peripheral wall portion 4 and a flange portion 5 protruding from one axial end of the peripheral wall portion 4 toward the internal space of the peripheral wall portion. The flange portion 5 is formed at the one end portion over the entire circumferential direction of the peripheral wall portion 4, thereby forming a circular through hole 1.1 through which the shaft (rotating shaft) 12 is inserted. . One end of the circular ring-shaped element 3 is adhered to the other surface in the axial direction of the flange portion 5 through a fluororesin layer 10 having a hydroxyl group in a molecule, and a seal lip portion 8 is attached to the shaft 12. The other end is bent to the sealed fluid R side so as to press against the seal fluid R, and in such a state, the seal 1 is mounted between the housing 13 and the shaft 12. As described above, the seal lip 8 of the seal element 3 is pressed against the shaft 12 to prevent leakage of fluid from the contact surface with the shaft 12. In addition, in the rotating shaft seal 1, the seal 1 is attached (closely fitted) between the shaft 12 and the housing 13. For this purpose, a sealant 15 is provided on the outer peripheral side (back side) of the metal case 2. The sealant 15 is formed by, for example, a method of pressure-molding rubber such as acrylic rubber or fluorine rubber, or applying and drying a paste made with a solvent.

In the rotary shaft seal according to the present invention, the metal case is a member for holding and fixing the seal element so that the seal element comes into contact with the rotary shaft in a predetermined pressing state. For example, iron, aluminum, stainless steel, steel ( It can be obtained by appropriately processing a metal material such as carbon steel or special steel) into a shape and size according to the purpose by a metal press or the like. An annular metal, shown in FIGS. 1 and 2, in which a flange 5 projects from one end in the axial direction of the cylindrical peripheral wall 4 toward the inner space over the entire circumference of the peripheral wall 4. Case 2 is a particularly preferable configuration because it has good retention of the seal element and good mounting of the seal between the shaft and the housing, and requires a small number of processing steps.

Further, in the present invention, the surface to be bonded (the surface 5 A on the inner side of the case of the flange portion 5 in the case shown in FIG. 1) to which the fluororesin layer having a hydroxyl group in the molecule of the metal case is fused (bonded) The surface may be roughened by a known method such as sand plasting, sanding, and acid Z cleaning, and the surface of the metal case (including the surface to be adhered) may be subjected to a surface protection treatment by a known method. May be applied. The surface treatment applied to the metal case preferably has heat resistance at the heating temperature at the time of fusing the fluororesin having a hydroxyl group.

Since the rotary shaft seal of the present invention has a configuration in which the seal element is bonded to the metal case via a layer of a fluororesin having a hydroxyl group in the molecule, the fluorine element having a hydroxyl group in the molecule forming the adhesive layer is used. If the resin protrudes from the shaft-side end of the metal case into the shaft insertion through-hole, the fluororesin layer comes into contact with the rotating shaft, and the fluororesin falls off from the contact portion, which causes foreign matter to be removed. It may enter between the shaft and the sealing surface. Even when the fluororesin does not come into contact with the shaft, there is a concern that the state of contact of the seal element with the shaft fluctuates due to adhesion to the protruding fluororesin, thereby deteriorating the sealing performance. Thus, the fluororesin layer having a hydroxyl group in the molecule (fused layer) obtained by melting and solidifying between the sealing element and the metal case has a shaft end at the shaft end of the metal case. It is preferable that the end is not protruded from the end into the through hole for shaft insertion. The end on the shaft side is provided so as to be located deeper in the case than the end on the shaft side of the metal case. Is particularly preferred.

Therefore, for example, in the rotary shaft seal 1 using the annular metal case 2 and the circular ring-shaped seal element 3 shown in FIGS. 1 and 2, the circular through hole 1 in the surface 5 A to be bonded of the flange 5 is provided. A ring-shaped region around which the fluororesin having a hydroxyl group in the molecule does not exist (i.e., the circular through hole of the flange 5 on the surface 5A to be bonded of the flange 5 shown in FIG. 2 (b) 1 1 It is preferable to provide a region T 1) between the terminal portion 5a on the side and the circular through-hole 11 of the fluororesin layer 10 having a hydroxyl group in the molecule 10 between the terminal portion 10a on the side of FIG. D 3) in the above is preferably not less than 0.1 mm. However, if the width of the ring-shaped region (D3 in Fig. 2 (b)) in which the fluorine resin having a hydroxyl group in the molecule does not exist exceeds 3 mm, the circular ring-shaped seal element 3 is attached to the shaft 2 On the other hand, it is difficult to make contact with a sufficiently high pressing force, so that the width is preferably 3 mm or less.

Further, from the viewpoint of the adhesive force between the seal element 3 and the metal case 2, the layer 10 of the fluororesin having a hydroxyl group in the molecule has an area of 20 to 100% of the surface 5 A to be bonded of the flange 5. Preferably, it is provided so as to cover the area (in the case of 100%, the axial end of the fluororesin layer having a hydroxyl group in the molecule coincides with the axial end of the metal case). More preferably, it is provided so as to cover 70% of the area. ―

Also, in the rotary shaft seal 1 using the annular metal case 2 and the circular ring-shaped seal element 3 shown in FIGS. 1 and 2, usually, the circular through hole 1 of the flange 5 of the annular metal case 2 is used. The distance (D 1 in FIG. 1) between the end 5 a on the first side and the shaft 12 is preferably about 0.7 to 3.0 mm, and the circular shape of the flange 5 in the circular ring-shaped seal element 3. The amount of protrusion (D2 in FIG. 2 (A)) from the end portion 5a of the through hole 11 to the shaft 12 is preferably about 210 mm. .

In the rotary shaft seal of the present invention, the thickness of the fluororesin layer having a hydroxyl group in the molecule is also important, and the thickness is preferably 5 to 100 μm, more preferably 10 to 70 / im. If the thickness is less than, sufficient adhesive strength cannot be obtained, and the workability deteriorates.If the thickness exceeds 100 111, the fluororesin layer having a hydroxyl group in the molecule itself is broken, and the adhesiveness may be reduced. This is not preferred.

The rotating shaft seal of the present invention has a structure in which hydroxyl is contained in the molecule between the metal case and the seal element. The fluororesin having a hydroxyl group in the molecule is melted and solidified by sandwiching a fluororesin having a group, heating and pressurizing such a stack, and then cooling. That is, a seal element containing PTFE as a main component is used as it is without being subjected to a special surface treatment (an activation treatment such as a plasma treatment or a metal sodium treatment). A fluorine resin having a hydroxyl group in the molecule is sandwiched between the case and the case (first step), and the stacked material is heated and compressed (second step), and then cooled under a load (third step). Through the first to third steps, the fluororesin having a hydroxyl group in the molecule is melted and solidified, and is fused to the metal case and the seal element. As a result, a rotary shaft seal is obtained in which the seal element is integrally formed via a fusion layer of a fluororesin having a hydroxyl group in the molecule.

In the present invention, it is preferable that the melting point of the fluororesin having a hydroxyl group in the molecule is lower than the melting point of PTFE (320 to 360 ° C) constituting the seal element. As described above, in the rotating shaft seal of the present invention, a fluorine resin having a hydroxyl group in a molecule is sandwiched between a metal case and a seal element, and the stack is heated and compressed to obtain a fluorine resin having a hydroxyl group in a molecule. It is produced by melting and solidifying the resin.If the melting point of the fluororesin having a hydroxyl group in the molecule is equal to or higher than the melting point of the PTFE constituting the sealing element, a hydroxyl group is formed in the molecule. If the heating is performed so that the fluorine resin contained therein is sufficiently melted, the heat deformation of the sealing element becomes large, and the sealing performance of the obtained rotary shaft seal decreases. In addition, if a fluororesin having a hydroxyl group in the molecule is used, the melting point of which is lower than the melting point of PTFE (320 to 360 ° C) constituting the sealing element, the hydroxyl group in the molecule is increased. In a cooling process after sandwiching a fluororesin with a resin between the metal case and the seal element and heating and compressing, the polytetrafluoroethylene constituting the seal element has hydroxyl groups in the molecule before it solidifies. The fluororesin solidifies first to fix the seal element, thereby suppressing heat shrinkage of the seal element. If the present inventors cannot sufficiently suppress the thermal shrinkage of the seal element, residual strain will occur in the seal element portion of the manufactured rotary shaft seal, causing unintended deformation (such as waving) or adhesive force. It has been found that problems such as peeling occur even with a slight rise in the operating environment temperature. Yotsu In order to sufficiently exhibit the effect of suppressing heat shrinkage of the seal element, a fluororesin having a hydroxyl group in the molecule must have a melting point that is at least 10 ° C lower than the melting point of the polytetrafluoroethylene constituting the sealing element used. It is preferable to use a compound having a temperature lower by 15 ° C. or more. If the melting point of the fluororesin having a hydroxyl group in the molecule is too low, the heat resistance of the resin itself becomes insufficient, so that the high-temperature environment of the rotating shaft seal (specifically, at 150 ° C or more) In use, there is a danger that the adhesive strength will be reduced, the sealing element will peel off, and the sealing fluid will leak out.Therefore, fluoropolymers having a hydroxyl group in the molecule have a melting point of 260 ° C or higher. Preferably, one is used.

In the present invention, the fluororesin having a hydroxyl group in the molecule may be in the form of a powder, a pellet, a rod, a film, or the like. From the viewpoint of handling (handling) at the time of sandwiching work between the sealant and the metal case, it is preferably formed into a rod shape or a film shape, and particularly preferably formed into a film shape. . In addition, if it is formed into a film, the uniformity of the properties of the fusion layer obtained by melting and solidifying is excellent, and the metal case and the seal element are more firmly adhered. Further, the setting of the fusion region with respect to the seal element is advantageous because it can be easily performed only by changing the shape and size of the film. Therefore, the fusion layer obtained by melting and solidification is formed in a state protruding from the axial end of the metal case (periphery of the circular through hole through which the shaft is inserted), and the contact state of the sealing surface changes, '' The problem of deteriorating the sealing performance can be avoided. When a fluororesin having a hydroxyl group in a molecule is formed into a film, the fluororesin may be formed by a hot-melt method; an extrusion method; a cutting method; a solvent casting; and an aqueous or organic solvent-based dispersion (dispersion). The film may be formed according to a known resin film forming method such as a method of coating a base material to form a continuous film and peeling the film from the substrate.

In the present invention, a stack in which a fluorine resin having a hydroxyl group in a molecule is sandwiched between a seal element and a metal case is heated and compressed.In this case, in order to obtain a high adhesive force, At the boundary between (the layer of) the seal element and the fluororesin having a hydroxyl group in the molecule, the PTFE in the seal element and the fluororesin having the hydroxyl group in the molecule are dissolved together to form a fused part. preferable. Therefore, during heating and compression of the stack The heating temperature is preferably a temperature higher than the melting point of PTFE constituting the sealing element to be used, more preferably a temperature higher than the melting point of the PTFE by 5 ° C or more, and more preferably 30 ° C than the melting point of the PTFE. It is particularly preferable to set the temperature higher than C. When the heating temperature is 400 ° C or higher, the PTFE constituting the seal element is thermally decomposed. Therefore, the heating temperature is preferably set to less than 400 ° C.

The compressive force (load) during heating and compression is usually 0.01 to 10 MPa, preferably 0.01 to 5 MPa, and particularly preferably 0.05 to 1 MPa. The heating / compression time varies depending on the heating temperature, compression force (load), etc., but is generally about 30 seconds to 30 minutes, preferably 5 to 30 minutes, and more preferably about 5 to 15 minutes.

Further, in the present invention, it is preferable to cool the stack as it is (that is, cool it under load) after heating and compressing the stack in order to achieve high adhesive strength. . By cooling while applying the compressive force (load) during such heating and compression, the adhesive force is further improved. The load at the time of cooling is usually 0.01 to 10 MPa, preferably 0.01 to 5 MPa, and particularly preferably 0.05 to LMPa. Hereinafter, a specific example of a method of manufacturing the rotating shaft seal of the present invention will be described in detail with reference to a manufacturing example of the rotating shaft seal 1 illustrated in FIG.

First, as shown in FIG. 3 (a), a cylindrical peripheral wall portion 4 and a flange portion 5 projecting from one axial end of the peripheral wall portion 4 to the internal space side of the peripheral wall portion (the flange portion 5 is An annular metal case 2 formed over the entire area in the circumferential direction of the peripheral wall portion 4), formed from a fluororesin having a hydroxyl group in the molecule by molding and processing, and made of a fluororesin having a hydroxyl group in the molecule. A circular ring-shaped sealing element 3 made of a circular ring-shaped film 10A and PTFE (or PTFE composition) is prepared. (In Fig. 1, the sealant is placed on the back side of the annular metal case 2. The layers are shown, but are not shown here.) The members are aligned so that the centers of the circular through holes of these members overlap on the same axis.

Next, as shown in FIG. 3 (b), a circular ring-shaped film 1OA made of a fluororesin having a hydroxyl group in the molecule is placed on the inner surface 5A of the flange 5 of the annular metal case 2 on the case. It is made of fluororesin having a hydroxyl group in the molecule between the metal case 2 and the circular ring-shaped seal element 3. A stack 20 is made by sandwiching the circular ring-shaped film 1 OA.

Next, as shown in FIG. 4, a thermostatic chamber 17 in which a pair of upper and lower press plates 15 As 15 B with their flat surfaces facing each other in parallel was prepared, and the thermostatic chamber 17 was previously prepared. A cylindrical compression jig 21 is heated to the same temperature as the melting point of the PTFE that forms the seal element 3 inside the thermostat, and the temperature is set to the same temperature as the melting point of the PTFE that forms the seal element. Into 17, the above-mentioned stack 20 is put, and a columnar compression jig 21 is placed on the circular ring-shaped seal element 3 of the stack 20, and then the inside of the thermostat is cooled. The compression jig 21 is mounted on the press plates 15A and 15B by setting the temperature to a desired temperature within the range of not less than the melting point of PTFE constituting the seal element 3 and less than 400 ° C. Heating / compression is performed by sandwiching the piled product 20 and holding it for a predetermined time. Here, the press plates 15A and 15B are connected to means (not shown) for moving them by, for example, hydraulic pressure, pneumatic pressure, or the like. The columnar compression jig 21 is used so that the pressure by the press plates 15A and 15B is transmitted uniformly (particularly to the seal element) to the stack 20. Usually, the outer diameter is smaller than the inner diameter of the cylindrical peripheral wall 4 of the metal case 2 and is obtained by processing a metal such as steel or aluminum, and a circular ring-shaped seal is used. An element larger than the outer diameter of element 3 is used.

Next, with the compression jig 21 and the stack 20 sandwiched between the press plates 15A and 15B, the stacked structures (press plates 15A and 15 B. Take out the compression jig 21 and the stack 20) from the thermostatic chamber 17 and leave it naturally (air cooling), or contact the stack with a cooling jig such as a metal plate. Or forced cooling such as water cooling of the stacked structure. The cooling is performed until the temperature becomes lower than the melting point of the fluororesin having a hydroxyl group in the molecule. This is because the heat shrinkage of the seal element is fixed by sufficiently cooling and solidifying the fluororesin having a hydroxyl group in the molecule. If the forced cooling is performed, the cooling time can be shortened, which is more effective in shortening the manufacturing time.

Thereafter, when the press plates 15A and 15B and the compression jig 21 are removed, the circular ring-shaped seal element 3 is attached to the ring-shaped metal case 2 to melt the fluorine resin having a hydroxyl group in the molecule. The rotating shaft seal 1 adhered and fixed by the adhesion layer is obtained.

In FIGS. 1 to 4, the inner surface 5 of the flange 5 of the annular metal case 2 A shows a seal having a configuration in which a seal element 3 having a seal lip portion is adhered, but when another seal element having a dust lip portion or the like is attached, the outer surface 5 B of the flange portion 5 (surface 5 (The opposite side to A) also forms a stack with another seal element stacked with a fluorine resin having a hydroxyl group in the molecule (a film) interposed therebetween, and heats and compresses the stack. , And cooling may be applied.

Here, the heating and compression of the stack were performed by pressing (compressing) the stack in a constant temperature bath. However, the stack was heated and compressed by using a known hot press apparatus having a heating plate. It may be carried out by hot pressing heavy materials.

In the rotary shaft seal according to the present invention, the shear peeling torque measured between the seal element and the metal case by a method described later is 80 O kgf · cm or more at room temperature (25 ° C.) and 150 ° C. (° C or higher) and 300 kgf'cm or more at cryogenic temperatures (−40 ° C or less).

The use of the rotary shaft seal of the present invention is not particularly limited, but is used for an engine shaft (sealing fluid: engine oil), for a compressor of an air conditioner (sealing fluid: lubricating oil and refrigerant), for a supercharger (sealing fluid: Suitable for high temperature and high pressure gas), turbocharger (sealed fluid: high temperature and high pressure gas), etc. In particular, since the fluororesin layer having a hydroxyl group in the molecule has excellent oil resistance, the rotary shaft seal of the present invention is particularly suitable for engine shafts. It has sufficient resistance to engine oil, which is a sealing fluid when used for engine shafts, especially high-temperature engine oil, and maintains its excellent adhesion to metal cases and seal elements for a long time.

In the present specification, the melting point of PTF E. and the melting point of the fluororesin having a hydroxyl group in the molecule are values obtained by DSC (differential scanning calorimetry) analysis.

Example

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. It should be noted that the present invention is not limited by the embodiments described below.

Example 1

Using a fluororesin film containing hydroxyl groups in the molecule, the manufacturing procedure shown in Figures 3 and 4 In this way, a steel shaft and a PTFE seal element were bonded together to produce a rotary shaft seal integrally formed.

The steel case is annular and has an inner diameter (D4 in Fig. 3 (a)) of 58.5 mm0 and an inner diameter of a circular through-hole (Fig. 3 (a)). D5) is 46.5mm0, wall thickness (D6 in Fig. 3 (a)) is 0.8mm, and the height of the cylindrical peripheral wall (D7 in Fig. 3 (a)) is 7.0mm did.

The PTFE sealing element is made of PTFE compound (per 100 parts by weight of PTFE, contains 5 parts by weight of molybdenum disulfide (solid lubricant) and 5 parts by weight of glass fiber), and has a thickness (Fig. 3 (a)). D 8) 0.8mmx outer diameter (D 9 in Fig. 3 (a)) 58.

A circular ring-shaped sheet (without surface treatment) of 45 mm x inside diameter (D 10 in Fig. 3 (a)) 35. πιπι was used. The melting point of PTFE in the PTFE sealing element (JI

According to 5 K7121, DSC analysis (temperature rise 10 ° C / min) is 327 ° C.

For a fluororesin film having a hydroxyl group in the molecule, a hydroxyl group-containing PFA (melting point: 310 ° C) manufactured by Daikin Industries, Ltd. is formed into a film and the thickness (D in Fig. 3 (a)) 1 1) 85 / mx outer diameter (D 12 in Fig. 3 (a)) 56. 50mm x inner diameter (D 13 in Fig. 3 (a)) 50.5 Omm0 .

The compression jig used was a cylinder made of steel with a height of 15 mm and an outer diameter of 58.4 mm and weighing 500 g.

When aligning the metal case and the hydroxyl group-containing PFA film, the size (area) of the hydroxyl group-containing PFA film is 50.

9%, the width around the circular through hole on the surface to be bonded of the flange 2. The hydroxyl group-containing PFA film was not overlapped in the area of Qmm.

Heating and compression were performed at 360 ° C. O. 06 MP ax for 30 minutes. For cooling after heating and compression, the press plate and the compression jig were left as they were, and the air was cooled for about 5 minutes until the compression jig reached approximately 250 ° C. The bonded surface of the flange of the metal case in the finished product (ie

In Fig. 3 (b), the size (area) of the fused area of the hydroxyl group-containing PFA to the inner surface 5A) of the flange 5 was 98.0%. In addition, around the through-hole on the surface to be bonded, a region (ring-shaped region) with a width of 0.1 mm where no hydroxyl group-containing PFA is present is formed. Had been. The thickness of the hydroxyl group-containing PFA layer was 15 to 40 zm.

The shearing and peeling torque between the metal case and the seal element of the completed rotary shaft seal was measured at room temperature (20 ° C) using the jig shown in Fig. 5. As a result, the jig slipped off the seal element before the seal element peeled from the metal case. Since the torque when this slip occurred was 800 kgf · cm, the shear peeling torque between the metal case and the seal element was determined to be 800 kgf′cm or more. The jig for measuring the shear-peeling torque shown in FIG. 5 includes an outer jig 31 for fixing the metal case, jigs 32 and 33 for tightening and rotating the seal element, and a tightening bolt 34. That is, the outer jig 31 has a cylindrical shape large enough to fit the metal case 2, and the metal case 2 is fitted into the outer jig 31 and fixed with a vice, etc. 1 is fixed. Tightening the seal element 'The jigs 32 and 33 for rotation are mounted on the disc-shaped substrate 33 a whose outer diameter is slightly smaller than the inner diameter of the outer jig 31 for fixing the metal case. A cylindrical projection 33b large enough to be inserted into the through hole of the metal case 2 (larger than the through hole of the seal element 3) is provided, and further inserted into the through hole of the seal element 3 on the projection 33b. The upper jig 32 is provided with a protrusion 33 c having a size smaller than the inner diameter of the cylindrical peripheral wall portion 4 of the metal case 2. Although the through-hole is large, the through-hole of the metal case 2 is also formed with a small cylindrical projection 32b. The tightening bolt 34 is adapted to be screwed into a screw hole formed in the axis of the upper jig 32 and the lower jig 33. Only the seal element 3 is clamped (tightened) by the cylindrical projection 32b of the upper jig 32 and the cylindrical projection 33b of the lower jig 33, and a rotational torque is generated.

Example 2

The steel case (the inner diameter of the cylindrical peripheral wall (D 4 in Fig. 3 (a)) whose surface is sanded is 99.6mm0, and the inner diameter of the circular through hole defined by the flange (Fig. 3 (a) D5) in the figure is 88.2mm0, otherwise it is an annular case with the same dimensions as the steel case of Example 1) and thickness (D8) in figure 3 (a) 0.8mmx outer diameter ( D 9 in Fig. 3 (a) 99.5 mm0x inside diameter (D 10 in Fig. 3 (a)) 76. Omm ^ PTFE compound (actual The same sheet as in Example 1) and the same hydroxyl group-containing PFA (melting point: 310 ° C) as in Example 1 were formed into a film, and the thickness (D 1 1) in Figure 3 (a) 85 mx Outer diameter (D 12 in Fig. 3 (a)) 98.0mm <2ix Inner diameter (D 13 in Fig. 3 (a)) 92. Process into a circular ring of πίπι This was carried out at 360 ° C. under a pressure of 0.06 MPa for 30 minutes. After heating and pressurization, the mixture was air-cooled while maintaining the pressurized state to produce a rotary shaft seal.

When aligning the metal case with the hydroxyl group-containing PFA film, the size (area) of the hydroxyl group-containing PFA film was 53.2% of the total area of the bonded surface of the flange portion of the metal case. The hydroxyl group-containing PFA film was not overlapped on the 1.9 mm wide area around the through hole on the surface to be bonded.

In the finished product after bonding, the area of the hydroxyl group-containing PFA layer is 99.1% of the area of the entire bonded surface of the flange of the metal case. Existence An area (ring-shaped area) with a width of 0.2 mm without PFA was formed. In addition, the thickness of the layer of hydroxyl group-containing PFA was 10 to 60 / m.

The shear peeling torque between the metal case and the seal element of the completed rotary shaft seal was measured in the same manner as in Example 1.The jig was removed from the seal element before the seal element was peeled from the metal case. I slipped. Since the torque when this slip occurred was 80 Okgf · cm, the shear peeling torque between the metal case and the sealing element was determined to be 80 Okgf · cm or more.

Example 3

A rotary shaft seal was produced in the same manner as in Example 1 except that a ring-shaped steel case (the dimensions were the same as in Example 1) whose surface was sanded was used. The size (area) of the fused area of the hydroxyl group-containing PFA on the bonded surface of the flange of the metal case in the finished product was 98.0%. The shear peeling torque between the metal case and the seal element of the completed rotary shaft seal was measured in the same manner as in Example 1.The jig slipped from the seal element before the seal element peeled from the metal case. I have. Since the torque when this slip occurred was 80 Okgf · cm, the shear peeling torque between the metal case and the sealing element was determined to be 800 kgf · cm or more. Example 4

The rotary shaft seal was replaced in the same manner as in Example 1 except that the annular case was replaced with an aluminum case with the same dimensions as the steel case used in Example 1 but without surface treatment (as is). Produced. The size (area) of the fused area of the hydroxyl-containing PFA to the surface to be bonded of the flange of the metal case in the finished product was 98.0%.

The shear peeling torque between the metal case and the seal element of the completed rotary shaft seal was measured in the same manner as in Example 1.The jig was removed from the seal element before the seal element was peeled from the metal case. I slipped. Since the torque when this slip occurred was 800 kgf · cm, the shear peeling torque between the metal case and the sealing element was judged to be 80 Okgf · cm or more.

Comparative Example 1

A PTFE sheet treated with metallic sodium (the PTFE sheet used in Example 1 treated with metallic sodium) was used, and the same metal case as in Example 1 was used. Laminate via adhesive (BANI-620T (Maruzen Petrochemical Co., Ltd.)), heat at 170 ° C x O.06MP ax for 5 minutes, compress and then further at 170 ° C for 15 hours Reheated.

The metal PTFE treatment of the PTFE sheet was performed by immersing the PTFE sheet in tetra-etch (manufactured by Junye Co.) for 30 seconds, followed by washing with acetone and then water. When the shear-peeling torque between the metal case and the seal element of the completed rotary shaft seal was measured in the same manner as in Example 1, only the seal element rotated at 500 kgf · cm.

Comparative Example 2

As shown in Fig. 5, the inner case 41 made of steel and rubber elastic body 42 made of acrylic rubber are used. The metal case 2 and the seal element 3 are the same as in the first embodiment, and the clamp type rotary shaft is used. A seal was made. When the shear peeling torque between the metal case and the seal element of the completed rotary shaft seal was measured in the same manner as in Example 1, only the seal element rotated at 250 kgf · cm.

Next, the rotating shaft seals of Examples 3 and 4 and Comparative Example 1 produced above were Heat resistance test and cold resistance test

[Heat resistance test]

The rotating shaft seal was subjected to the same shearing and peeling test as described above under an atmosphere of 150 ° C., and the peeling torque was measured.

[Cold resistance test]

The rotating shaft seal was subjected to the same shearing and peeling test as described above under an atmosphere of 140 ° C., and the peeling torque was measured.

The above test results are shown in Table 1 below.

Table 1 Shear peeling torque

(20 ° C)

[kgf'cmj 800≤ 800≤ 800≤ 800≤ 500 250 Heat resistance test

(Under 150 ° C atmosphere

No peeling at the time Not performed Not performed 300 ≤ 300 ≤ 200 Not performed Torque)

[kgf 'cmj

Cold resistance test

(Under -40 C atmosphere

Peeling at

Not implemented Not implemented 1000 ≤ 1000 ≤ 650 Not implemented Torque)

[kgf -cm]

Industrial applicability

As is apparent from the above description, according to the present invention, a simple structure is used without using a dedicated metal part or rubber elastic body, and the seal element mainly composed of PTFE is firmly attached to the metal case. It is possible to obtain a highly reliable rotating shaft seal that is fixed and has a very low possibility of occurrence of a critical path. In addition, since the rotating shaft seal of the present invention has a high resistance to the temperature change in the adhesive force between the seal element and the metal case, the sealing performance hardly changes even when the temperature of the use environment changes. High reliability is obtained. Also, since the sealing element can be fixed to the metal case with a small number of steps, the manufacturing time can be greatly reduced as compared with the conventional clamp type seal. Also, unlike the use of epoxy resin-based adhesives, which are generally known as heat-resistant adhesives that adhere to metals, they do not require long-time heating, and work for applying adhesives Since there is no complexity such as complicated management of conditions and equipment, the rotary shaft seal of the present invention can perform industrial production extremely efficiently.

This application is based on Japanese Patent Application No. 200-410-588 and Japanese Patent Application No. 200-410-237, the contents of which are incorporated in full herein. Is done.

Claims

The scope of the claims

1. A rotating shaft seal with a structure in which a sealing element mainly containing polytetrafluoroethylene is contained in a metal case,

A rotary shaft seal, wherein a seal element mainly composed of polytetrafluoroethylene is adhered and integrated with a metal case via a layer of a fluororesin having a hydroxyl group in a molecule.

2. An annular metal case in which a metal case has a flange portion protruding from one axial end of the cylindrical peripheral wall portion toward the internal space, and a circular through-hole through which the rotation shaft is inserted is inserted into the flange portion. And

The seal element has a ring shape, and is bonded to a flange of the annular metal case via a layer of a fluororesin having a hydroxyl group in a molecule,

The fluororesin layer having a hydroxyl group in the molecule is provided so that the terminal portion on the rotating shaft side does not protrude into the through hole from the terminal portion on the rotating shaft side of the flange portion. The rotary shaft seal according to claim 1, wherein:

3. The layer of a fluororesin having a hydroxyl group in the molecule is provided so as to cover an area of 20 to 100% of the surface to be bonded of the flange portion. The rotating shaft seal described in item 2.

4. The fluororesin having a hydroxyl group in a molecule is not present in a ring-shaped region having a width of 0.1 mm or more around a circular through-hole on a surface to be bonded of a flange portion. Rotary shaft seal according to item 2.

5. The rotary shaft seal according to any one of claims 1 to 4, wherein the thickness of the fluororesin layer having a hydroxyl group in the molecule is 5 to 100 m.

6. A method for producing a rotary shaft seal in which a seal element mainly composed of polytetrafluoroethylene is integrally formed with a metal case,

A fluorine resin having a hydroxyl group in the molecule between the seal element mainly composed of polytetrafluoroethylene and the metal case, the melting point of which is the melting point of polytetrafluoroethylene that constitutes the seal element After heating and compressing the obtained stack, the stack is cooled under a load, and the hydroxyl group is contained in the molecule. A method for producing a rotary shaft seal, comprising melting and solidifying a fluororesin having the following characteristics.

7. The method for producing a rotary shaft seal according to claim 6, wherein the fluororesin having a hydroxyl group in a molecule is a molded product molded into a film.

8. The range of claim 6, wherein the difference between the melting point of the fluororesin having a hydroxyl group in the molecule and the melting point of polytetrafluoroethylene constituting the sealerment is 1 ° C or more. A manufacturing method of the rotating shaft seal according to the above.