gasket

Abstract

The present application provides a gasket having excellent vibration-damping and vibration-proof properties. A gasket having an elastic portion comprising a rubber having a dynamic spring constant Kd and a static spring constant Kst ratio, i.e., a dynamic ratio Kd / Kst, of 2.5 or less. The dynamic spring constant Kd represents a constant measured under the conditions of 23±2°C, 100 Hz, and a strain amplitude of 0.1% as described in JIS K6394:2007, and the static spring constant Kst represents a constant measured under the conditions of 23±2°C and a strain amplitude of 0.1% as described in JIS K6394:2007.

Description

TECHNICAL FIELD

[0001] The present application relates to a gasket. BACKGROUND

[0002] Nowadays, in various fields such as automobiles, a gasket in which a rubber and a metal are stacked is used. The gasket is required to have high sealing property, and therefore, researches for improving compression set resistance (CS), stress relaxation property, and rubber hardness are conducted. Patent Literature 1 (International Publication No. 2011 / 024812) discloses a metal gasket in which a metal sheet and a plurality of sealing members composed of an elastomer are stacked (claim 1, paragraph

[0044] ).

[0003] In recent years, hybridization and electrification of automobiles are promoted, and development of environmentally friendly automobiles such as fuel cell vehicles is conducted. In these automobiles, a seal for an electric motor, a seal for a battery such as a secondary battery and a fuel cell, and a seal for a power control unit are used. Since an electric motor is used in hybrid automobiles, electric automobiles, fuel cell vehicles, and the like, vibration is generated at the time of driving the electric motor. Therefore, it is desired to suppress the vibration generated in these environmentally friendly automobiles. In addition, it is desired to suppress the vibration originating from a vibration source such as an electric motor in devices other than environmentally friendly automobiles.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: International Publication No. 2011 / 024812 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The gasket of Patent Literature 1 has high sealing property, but it is desired to further improve the vibration damping and vibration prevention effects. The present application has been achieved in view of the above circumstances, and provides a gasket having excellent vibration damping property and vibration prevention property.

[0009] MEANS OF SOLVING THE PROBLEMS

[0010] Each embodiment of the present application is as follows.

[0011] [1] A gasket having an elastic portion, the elastic portion containing a rubber having a dynamic spring constant Kd to static spring constant Kst ratio, that is, a dynamic ratio Kd / Kst of 2.5 or less.

[0012] (the dynamic spring constant Kd represents a constant measured under conditions of 23 ± 2°C, 100 Hz, and a strain amplitude of 0.1% as described in JIS K6394:2007,

[0013] Static spring constant Kst represents a constant measured at 23 ± 2°C, a strain amplitude of 0.1% according to JIS K6394:2007)

[0014] [2] The gasket according to the above [1], wherein the hardness of the rubber is 90 or less.

[0015] [3] The gasket according to the above [1] or [2], wherein the gasket has:

[0016] a metal plate; and

[0017] the elastic portion on one surface or both surfaces of the metal plate.

[0018] [4] The gasket according to any one of the above [1] to [3], wherein the rubber is nitrile rubber.

[0019] [5] The gasket according to any one of the above [1] to [4], wherein the gasket is a gasket for an electric motor.

[0020] [6] The gasket according to any one of the above [1] to [4], wherein the gasket is a gasket for an inverter housing.

[0021] Effects of Invention

[0022] The present application can provide a gasket having excellent vibration-damping properties and vibration-proof properties. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is an exploded perspective view of a case which is an example of a gasket to which an embodiment of the present application is applied. DETAILED DESCRIPTION

[0024] The sealing gasket of the present application has an elastic portion that contains a rubber having a ratio of dynamic spring constant Kd to static spring constant Kst, i.e., dynamic modulus Kd / Kst, of 2.5 or less. Here, the dynamic spring constant Kd represents a constant measured under the conditions of 23 ± 2°C, 100 Hz, and a strain amplitude of 0.1% as described in JIS K6394:2007. In addition, the static spring constant Kst represents a constant measured under the conditions of 23 ± 2°C and a strain amplitude of 0.1% as described in JIS K6394:2007. By making the dynamic modulus Kd / Kst of the rubber 2.5 or less, vibration from a vibration source is less likely to be transmitted to the sealing gasket. In addition, even in the case where vibration is transmitted from the vibration source to the elastic portion, the vibration is easily converted to thermal energy within the elastic portion. As a result, the sealing gasket can have excellent vibration damping and vibration prevention characteristics, and the sealing gasket can effectively prevent vibration from being transmitted from the vibration source to other members. In addition, the sealing gasket suppresses vibration from the vibration source, and thus can reduce noise resulting from the vibration and can improve the quietness of an apparatus having the sealing gasket. Typically, the elastic portion is composed of a rubber having a dynamic modulus Kd / Kst of 2.5 or less. For example, the sealing gasket can be used for a motor and an inverter housing, and can reduce vibration and noise generated from these apparatuses. In addition, the sealing gasket can be used inside a machine or apparatus, such as a motor vehicle, a robot, a household appliance, and the like, equipped with a motor or an inverter housing. In the case where the sealing gasket of the present application is used in a motor vehicle, vibration and noise can be reduced, and thus the vehicle can be driven in a comfortable state.

[0025] The dynamic spring constant Kd and the static spring constant Kst of the rubber constituting the elastic portion are measured as follows. The vulcanization rate of the rubber composition for the elastic portion is measured in advance based on JIS K6300-2, and the T c (90) (90% vulcanization time). Next, the dynamic modulus Kd / Kst of the rubber is measured by passing the rubber through a dynamic viscoelasticity measuring device (Rheology cThe rubber composition for the elastic portion was pressurized and vulcanized under the conditions of (90) to prepare a rubber sheet. Thereafter, the dynamic spring constant was measured by a tensile method under the conditions of 23 ± 2°C, 100 Hz, and a strain amplitude of 0.1% according to the forced vibration non-resonance method described in JIS K6394:2007. In addition, the static spring constant was measured by a tensile method under the conditions of 23 ± 2°C and a strain amplitude of 0.1% according to JIS K6394:2007. In addition, the dynamic ratio Kd / Kst was able to be calculated by dividing the static spring constant Kst by the dynamic spring constant Kd thus measured. As a measuring device for the dynamic spring constant and the static spring constant, for example, Rheogel-E4000 manufactured by UBM Co., Ltd. can be used. The dynamic ratio Kd / Kst is preferably 2.5 or less, more preferably 2.0 or less, and even more preferably 1.8 or less. In addition, the dynamic ratio Kd / Kst is preferably 0.5 or more, more preferably 1.0 or more. By making the value of the dynamic ratio within the above range, the gasket is able to have higher vibration-damping properties and vibration-proof properties. The dynamic spring constant is preferably 1.5 g / μm or less, more preferably 1.2 g / μm or less, and even more preferably 0.8 g / μm or less. By making the value of the dynamic spring constant within the above range, both excellent vibration-damping properties and vibration-proof properties and sealing properties of the gasket are able to be achieved.

[0026] The hardness of the rubber contained in the elastic portion (durometer A hardness) is preferably 90 or less, more preferably 85 or less, and even more preferably 80 or less. By making the hardness of the rubber within the above range, the gasket is able to have higher sealing performance and vibration-damping and vibration-proof properties. Note that the hardness of the rubber can be measured by a method based on JIS K6253.

[0027] The gasket of one embodiment has a metal plate and an elastic portion on one surface or both surfaces of the metal plate, the elastic portion containing a rubber having a dynamic modulus Kd / Kst of 2.5 or less. As the material of the metal plate, there is no particular limitation, and iron, aluminum, copper, or the like or an alloy thereof or the like, for example, SPCC (cold-rolled steel sheet), SPFC (cold-rolled high-tension steel sheet), mild steel, stainless steel sheet, aluminum, aluminum die cast, can be used. As the stainless steel sheet, SUS301, SUS301H, SUS304, SUS430, or the like can be used. The thickness of the metal plate is not particularly limited, and is preferably 100 to 2000 μm, more preferably 200 to 1000 μm. The metal plate can be used in a degreased state, and the metal surface can be roughened by shot blasting, scotch blast, hairline, dull finish, or the like as needed. The elastic portion can be bonded to the metal plate by containing an adhesive component or by providing an adhesive layer between the elastic portion and the metal plate. As the adhesive component and the component of the adhesive layer, there is no particular limitation as long as the adhesion of the metal plate and the elastic portion can be improved, and a resin-based vulcanization adhesive such as a phenolic resin, an epoxy resin, or the like can be used. As the phenolic resin, any thermosetting phenolic resin such as a cresol novolac type phenolic resin, a cresol resol type phenolic resin, an alkyl-modified phenolic resin, or the like can be given. In addition, as the epoxy resin, a cresol novolac type epoxy resin can be given, in which case a bisphenol novolac type phenolic resin is used as a curing agent, and an imidazole compound is used as a curing catalyst.

[0028] The rubber constituting the elastic portion is preferably nitrile rubber (NBR). Nitrile rubber is a copolymer of butadiene and acrylonitrile. The nitrile rubber (NBR) can be hydrogenated or not. As the nitrile rubber, various NBRs of very high nitrile content (nitrile content of 43% or more), high nitrile content (nitrile content of 36 to 42%), middle high nitrile content (nitrile content of 31 to 35%), middle nitrile content (nitrile content of 25 to 30%), and low nitrile content (nitrile content of 24% or less) can be used.

[0029] The rubber can further include carbon black, silica, a filler, a plasticizer, an additive, an antioxidant, a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, or the like. The type of carbon black can be appropriately selected according to the purpose of the gasket, and for example, SAF carbon black, ISAF carbon black, HAF carbon black, EPC carbon black, XCF carbon black, FEF carbon black, GPF carbon black, HMF carbon black, SR carbon black, FT carbon black, MT carbon black, or the like can be used. As the additive, calcium metasilicate, calcium carbonate, zinc oxide, stearic acid, paraffin wax, or the like can be given. Further, as the vulcanizing agent, there is no particular limitation as long as it is a vulcanizing agent used for rubber, and for example, a sulfur-based vulcanizing agent, an organic peroxide-based vulcanizing agent, or the like can be given.

[0030] As the sulfur-based vulcanizing agent, for example, powdered sulfur, flower of sulfur, precipitated sulfur, colloidal sulfur, high-dispersibility sulfur, insoluble sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, dibenzothiazole disulfide, N,N'-dithio-bis(hexahydro-2H-azepin-2-one), phosphorus-containing polysulfide, high-molecular polysulfide, or the like can be given. As the organic peroxide-based vulcanizing agent, ketone peroxide, peroxide ester, diacyl peroxide, dialkyl peroxide, or the like can be given. Further, a vulcanization accelerator, a vulcanization aid, or the like can be used as needed.

[0031] Figure 1 An exploded perspective view of a case showing an example of a gasket to which one embodiment is applied. Figure 1 The case 100 shown is composed of two members, a housing member 200 and a cover member 300. The housing member 200 and the cover member 300 integrally have flange portions 201, 301 around the respective opening portions. A single gasket 1 is disposed between the opposing abutting surfaces 202, 302 of the flange portions 201, 301. The abutting surfaces 202, 302 of the flange portions 201, 301 are formed in a band shape with a certain width so as to surround the outer periphery of the opening portions of the housing member 200 and the cover member 300. The portions where bolt holes 203, 303 are formed partially project to the side.

[0032] The gasket 1 has a ring-shaped portion la and projecting portions lb. The ring-shaped portion la is formed in a certain width that is the same as the abutting surfaces 202, 302 of the flange portions 201, 301 of the housing member 200 and the cover member 300. The projecting portions lb partially project to the side in a manner that they are connected from the ring-shaped portion la by a smooth curve at positions corresponding to the respective bolt holes 203, 303 of the flange portions 201, 301. In each of the projecting portions lb, a bolt hole 11 corresponding to the respective bolt holes 203, 303 of the flange portions 201, 301 is formed.

[0033] Further, the case 100 is fastened by inserting and passing the bolt 400 through the bolt holes 203, 303, 11, thereby fastening the three of the housing member 200, the lid member 300, and the gasket 1 as one. The abutting surfaces 202, 302 of the flange portions 201, 301 are sealed by the gasket 1 sandwiched between the flange portions 201, 301.

[0034] The gasket 1 is not particularly limited as long as it has the above-described structure. In the above description, an example is shown in which the gasket 1 of one embodiment is used as a sealing member between the flange portions 201, 301 of the housing member 200 and the lid member 300 of the case 100. However, the gasket 1 of one embodiment is not limited to application to such a case 100, and can be widely applied to cases in which the abutting surfaces of two members are sealed.

[0035] The gasket is preferably a gasket for an electric motor.

[0036] Further, the gasket is preferably a gasket for an inverter housing.

[0037] In the production method of the gasket of one embodiment, for example, after a solution containing a rubber composition for the elastic portion is dropped and applied on a substrate such as a metal plate, the solution is heated, dried, and vulcanized, thereby producing the elastic portion. As the solution containing the rubber composition for the elastic portion, there is no particular limitation, and methyl ethyl ketone, toluene, ethyl acetate, or the like can be used.

[0038] Example

[0039] Hereinafter, a preferred embodiment of the present application will be specifically described on the basis of examples and comparative examples, but the present application is not limited to these examples.

[0040] (Examples 1 to 14 and Comparative Examples 1 to 5)

[0041] Each material was mixed using a pressurized kneader (manufactured by Japan SPINDLE Co., Ltd.) and an open roll (manufactured by Kansai Roll Co., Ltd.) and in a blend ratio shown in Table 1 below, thereby producing a rubber composition.

[0042] (Evaluation)

[0043] The following measurements were performed using the rubber composition obtained as described above.

[0044] (a) Measurement of hardness, tensile strength, and elongation of the elastic portion

[0045] The vulcanization rate of the rubber composition was measured in advance on the basis of JIS K6300-2, and T c (90) (90% vulcanization time). Next, the T cThe rubber composition was pressurized-vulcanized under the same conditions as in (a) above to prepare test pieces. For the test pieces, the hardness (durometer A hardness) based on JIS K6253 was measured, and the tensile strength and elongation based on JIS K6251 were measured.

[0046] (b) Measurement of Dynamic Spring Constant Kd

[0047] The rubber composition was pressurized-vulcanized under the same conditions as in (a) above to prepare test pieces having a thickness of 2 mm, a width of 4 mm, and a length of 20 mm. Next, the dynamic spring constant of the test pieces was measured by a tensile method using Rheogel-E4000 manufactured by UBM Co., Ltd. based on the forced vibration non-resonance method described in JIS K6394:2007 under conditions of 23 ± 2°C, 100 Hz, and a strain amplitude of 0.1%.

[0048] (c) Measurement of Static Spring Constant Kst

[0049] The rubber composition was pressurized-vulcanized under the same conditions as in (a) above to prepare test pieces having a thickness of 2 mm, a width of 4 mm, and a length of 20 mm. Next, the static spring constant of the test pieces was measured by a tensile method using Rheogel-E4000 manufactured by UBM Co., Ltd. based on JIS K6394:2007 under conditions of 23 ± 2°C and a strain amplitude of 0.1%.

[0050] (d) Calculation of Dynamic Magnification Kd / Kst

[0051] Based on the dynamic spring constant Kd and the static spring constant Kst measured using (b) and (c) above, the dynamic magnification Kd / Kst was calculated by the following equation.

[0052] Dynamic Magnification Kd / Kst = (Dynamic Spring Constant Kd) / (Static Spring Constant Kst)

[0053] (e) Measurement of Loss Coefficient of Gasket

[0054] The surface of a SPCC steel sheet having a thickness of 400 μm was treated with zinc phosphate. Thereafter, after the SPCC steel sheet was coated with methyl ethyl ketone (MEK) in which a phenolic resin (Thixon 715 (trade name)) was dissolved, it was dried. Next, the rubber composition prepared in each example was dissolved in methyl ethyl ketone (MEK). Thereafter, on the SPCC steel sheet on which the MEK solution containing the phenolic resin was coated, the MEK in which the rubber composition was dissolved was coated, and then the rubber composition was vulcanized in an oven at 200°C for 3 minutes, whereby an elastic portion having a thickness of 120 μm was formed on the SPCC steel sheet (metal sheet). As a result, a gasket having an elastic portion on the SPCC steel sheet (metal sheet) and having a width of 17 mm and a length of 250 mm was obtained. The gasket thus obtained was attached to a SUS301 sheet having a thickness of 250 μm, a width of 17 mm, and a length of 250 mm via a cyanoacrylate-based adhesive, whereby a sample for loss tangent measurement was obtained. Note that it was confirmed through a preliminary experiment in advance that as long as an adhesive that can attach the gasket to the SUS301 sheet is used, the type of the adhesive does not affect the value of the loss tangent.

[0055] Next, using an AS14PA5 (cantilever beam type) manufactured by Rion Co., Ltd., the loss tangent was measured based on JIS K7391:2008 using the half-value width method at a measurement temperature of 23 ± 2°C and at a resonance frequency of 2 times in a measurement range of 0 to 1 kHz. Furthermore, when the loss tangent was 0.03 or greater, it was determined that the damping and vibration-proof characteristics were good, and was evaluated as "O", and when the loss tangent was less than 0.03, it was determined that the damping and vibration-proof characteristics were poor, and was evaluated as "X". The composition of the rubber composition and the evaluation results of the damping and vibration-proof characteristics are shown in Table 1 below.

[0056]

[0057] The names of each material in Table 1 are shown below.

[0058] Nitrile rubber A: Nipol (registered trademark) DN3350 (ZEON Corporation, Japan)

[0059] Nitrile rubber B: JSR N237 (JSR Corporation)

[0060] Nitrile rubber C: JSR N220S (JSR Corporation)

[0061] Carbon black A (MT carbon black): THERMAX (registered trademark) N990LSR (Cancarb Corporation)

[0062] Carbon black B (SRF carbon black): HTC#SS (Shin Nittoku Carbon Co., Ltd.)

[0063] Carbon black C (SRF carbon black): ASAHI #50HG (Asahi Carbon Co., Ltd.)

[0064] Carbon black D (FEF carbon black): Seast (registered trademark) SO (Tokai Carbon Co., Ltd.)

[0065] Carbon black E (HAF carbon black): SHOBLACK (registered trademark) N330L (Cabot Japan K.K.)

[0066] Silica: Nipsil (registered trademark) LP (Dkshin Co., Ltd.)

[0067] Filling agent A: ActiGin VM56 (Hoffmann Mineral)

[0068] Filling agent B: Nyad (registered trademark) 400 (NYCO Minerals, Inc.)

[0069] Filling agent C: Baiyanhua (registered trademark) CC (Bai Shi Industry Co., Ltd.)

[0070] Plasticizer: ADEKACIZER (registered trademark) RS107 (ADEKA Co., Ltd.)

[0071] Additive A: Zinc oxide (Shouzheng Chemical Industry Co., Ltd.)

[0072] Additive B: DTST (Miyoshi Oil & Fat Co., Ltd.)

[0073] Additive C: NOCRAC 810-NA (Ouchi Shinko Chemical Industrial Co., Ltd.)

[0074] Additive D: SUNTIGHT (registered trademark) R (Seiko Chemical Co., Ltd.)

[0075] Sulfurizing agent A: Colloidal sulfur A (Tsurumi Chemical Industry Co., Ltd.)

[0076] Sulfurizing agent B: VULNOC (registered trademark) R (Ouchi Shinko Chemical Industrial Co., Ltd.)

[0077] Sulfurizing agent C: Peroxymon (registered trademark) F-40 (Nippon Oil Co., Ltd.)

[0078] Vulcanization accelerator A: NOCCELER (registered trademark) TBZTD (Ouchi Shinko Chemical Industrial Co., Ltd.)

[0079] Vulcanization accelerator B: NOCCELER (registered trademark) -CZ-P (Ouchi Shinko Chemical Industrial Co., Ltd.)

[0080] Vulcanization aid: TAIC (registered trademark) M60S (Mitsubishi Chemical Corporation)

[0081] According to the results of Table 1, it was found that by making the dynamic ratio Kd / Kst of the rubber constituting the elastic portion 2.5 or less, a gasket having a loss coefficient of 0.03 or more and excellent damping and vibration-proof characteristics can be obtained.

[0082] Explanation of Reference Signs

[0083] 1 Gasket

[0084] 1a Annular portion

[0085] 1b Protruding portion

[0086] 11 Bolt hole

[0087] 100 Box body

[0088] 200 Shell member

[0089] 201, 301 Flange portion

[0090] 202, 302 Butt surface

[0091] 203, 303 Bolt hole

[0092] 300 Cover member

[0093] 400 Bolt

Claims

1. A gasket having an elastic portion, the elastic portion comprising a rubber having a ratio of a dynamic spring constant Kd to a static spring constant Kst, that is, a dynamic ratio Kd / Kst, of 2.5 or less, the dynamic spring constant Kd is 1.0 g / μm to 1.5 g / μm, the dynamic spring constant Kd represents a constant measured under conditions of 23 ± 2°C, 100 Hz, and a strain amplitude of 0.1% as described in JIS K6394:2007, the static spring constant Kst represents a constant measured under conditions of 23 ± 2°C and a strain amplitude of 0.1% as described in JIS K6394:2007.

2. A gasket having an elastic portion, the elastic portion comprising a rubber having a ratio of a dynamic spring constant Kd to a static spring constant Kst, that is, a dynamic ratio Kd / Kst, of 2.5 or less, the dynamic spring constant Kd is 0.208 g / μm to 1.437 g / μm, the static spring constant Kst is 0.148 g / μm to 0.584 g / μm, the dynamic spring constant Kd represents a constant measured under conditions of 23 ± 2°C, 100 Hz, and a strain amplitude of 0.1% as described in JIS K6394:2007, the static spring constant Kst represents a constant measured under conditions of 23 ± 2°C and a strain amplitude of 0.1% as described in JIS K6394:2007.

3. The gasket of claim 1 or 2, wherein, the rubber has a hardness of 90 or less.

4. The gasket of claim 1 or 2, wherein, the gasket has: a metal plate; and the elastic portion on one surface or both surfaces of the metal plate.

5. The gasket of claim 1 or 2, wherein, the rubber is nitrile rubber.

6. The gasket of claim 1 or 2, wherein, the gasket is a gasket for an electric motor.

7. The gasket of claim 1 or 2, wherein, the gasket is a gasket for an inverter housing. the gasket is a gasket for an inverter housing.

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