阅读说明：本技术 密封件用橡胶组合物以及使用该密封件用橡胶组合物的密封件 (Rubber composition for sealing member and sealing member using same ) 是由 上田彰 吉田纱也佳 西原亮平 于 2020-03-06 设计创作，主要内容包括：本发明提供一种密封件用橡胶组合物,其包含橡胶成分100质量份、50～140质量份的二氧化硅、1～20质量份的硅烷偶联剂以及15～35质量份的炭黑。橡胶成分优选为乙烯－丙烯－二烯橡胶。(The invention provides a rubber composition for a sealing member, which comprises 100 parts by mass of a rubber component, 50-140 parts by mass of silica, 1-20 parts by mass of a silane coupling agent and 15-35 parts by mass of carbon black. The rubber component is preferably an ethylene-propylene-diene rubber.)

1. A rubber composition for a sealing member, which comprises 100 parts by mass of a rubber component, 50 to 140 parts by mass of silica, 1 to 20 parts by mass of a silane coupling agent, and 15 to 35 parts by mass of carbon black.

2. The rubber composition for a sealer according to claim 1, wherein,

the rubber component is an ethylene-propylene-diene rubber.

3. The rubber composition for a sealer according to claim 2, wherein,

the ethylene-propylene-diene rubber is prepared according to JIS K6300-1: 2013, or 30 to 60 at 100 ℃, wherein the ethylene-propylene-diene rubber contains 45 to 55 mass% of structural units derived from ethylene.

4. The rubber composition for a seal member according to any one of claims 1 to 3, wherein,

the silica is spherical.

5. The rubber composition for a seal member according to any one of claims 1 to 4,

the average particle size of the silicon dioxide is 5 nm-5 mu m.

6. The rubber composition for a seal member according to any one of claims 1 to 5,

no plasticizer is contained.

7. A sealing member comprising a crosslinked product of the rubber composition for sealing members according to any one of claims 1 to 6.

Technical Field

The present invention relates to a rubber composition for a sealing material and a sealing material using the same.

Background

A rubber seal for an apparatus for storing high-pressure hydrogen gas has a problem in that a foaming (blister) phenomenon is easily generated. The foaming phenomenon refers to the following phenomenon: the gas that has permeated into the rubber due to high pressure is affected by rapid decompression at high temperature and expands while remaining in the rubber, resulting in cracking of the rubber material.

International publication No. 2007/145313 (patent document 1) and international publication No. 2008/001625 (patent document 2) disclose rubber compositions in which silica is blended as a reinforcing material in silicone rubber. Further, japanese patent application laid-open publication No. 2015-206002 (patent document 3) discloses a rubber composition in which carbon black is blended into an ethylene-propylene-diene rubber (EPDM). Jp 2015-108104 a (patent document 4) discloses an EPDM O-ring containing carbon black and silica, and international publication 2003/104317 a (patent document 5) discloses an elastomeric compound containing carbon black and silica powder (microsilica).

Documents of the prior art

Patent document

Patent document 1: international publication No. 2007/145313

Patent document 2: international publication No. 2008/001625

Patent document 3: japanese laid-open patent publication (JP 2015-206002)

Patent document 4: japanese patent laid-open publication No. 2015-108104

Patent document 5: international publication No. 2003/104317

Disclosure of Invention

Problems to be solved by the invention

In a high-pressure hydrogen plant, the pressure of hydrogen to be treated is gradually increased, and a seal having more excellent sealing properties at low temperatures and high temperatures is required. However, a composition having excellent blister resistance at high temperatures is poor in low temperature properties (recovery at low temperatures), and a sealing material satisfying both properties has not yet been realized.

The present invention aims to provide a rubber composition for a seal capable of improving the sealing property of high-pressure gas at high temperature and low temperature, and a seal obtained by crosslinking the rubber composition for a seal.

Means for solving the problems

The present invention includes the following rubber composition for a sealing member and a sealing member using the rubber composition for a sealing member.

[1] A rubber composition for a sealing member, which comprises 100 parts by mass of a rubber component, 50 to 140 parts by mass of silica, 1 to 20 parts by mass of a silane coupling agent, and 15 to 35 parts by mass of carbon black.

[2] The rubber composition for a sealer according to [1], wherein the rubber component is an ethylene-propylene-diene rubber.

[3] The rubber composition for a sealer according to [2], wherein the ethylene-propylene-diene rubber is a rubber composition according to JIS K6300-1: 2013, or 30 to 60 at 100 ℃, wherein the ethylene-propylene-diene rubber contains 45 to 55 mass% of structural units derived from ethylene.

[4] The rubber composition for a sealing material according to any one of [1] to [3], wherein the silica is spherical.

[5] The rubber composition for a sealing material according to any one of [1] to [4], wherein the silica has an average particle diameter of 5nm to 5 μm.

[6] The rubber composition for a sealer according to any one of [1] to [5], wherein a plasticizer is not contained.

[7] A sealing material comprising a crosslinked product of the rubber composition for sealing materials according to any one of [1] to [6 ].

Effects of the invention

According to the present invention, a rubber composition for a seal capable of improving the sealing property of high-pressure gas at high and low temperatures, and a seal obtained by crosslinking the rubber composition for a seal can be provided.

Detailed Description

The rubber composition for a sealer comprises [ A ] a rubber component, [ B ] silica, [ C ] a silane coupling agent and [ D ] carbon black. Hereinafter, each component contained in the rubber composition for a gasket and optionally contained components will be described in detail.

[ A ] rubber component

As the rubber component, for example, there can be used: ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPM), nitrile rubber (NBR; acrylonitrile butadiene rubber), hydrogenated nitrile rubber (HNBR; hydrogenated acrylonitrile butadiene rubber), butyl rubber (IIR), fluoro rubber (FKM), silicone rubber (Q), and the like. As the rubber for the seal, EPDM, HNBR, FKM, and the like are preferable from the viewpoint of having good characteristics. The rubber component may be composed of only one kind, or may include two or more kinds.

The rubber composition for a gasket is crosslinked to form a gasket which does not cause foaming or gas leakage in a high-temperature high-pressure cycle test at 100 ℃ and 100MPa, which will be described later. Further, the rubber composition for a gasket does not cause gas leakage in a low-temperature high-pressure cycle test at a temperature of-40 ℃ and a pressure of 100MPa, which will be described later. The leakage gas in a low temperature environment generally occurs due to a decrease in the shape followability and the restorability of the seal. EPDM is a rubber excellent in low temperature properties (recovery at low temperature), chemical resistance, cleaning properties, and the like, and is less expensive than NBR, HNBR, FKM, Q, and the like, and therefore is one of rubber components suitable for sealing material applications.

EPDM is a terpolymer comprising structural units derived from ethylene, structural units derived from propylene, and structural units derived from a diene monomer. In the EPDM, the rubber characteristics can be controlled by adjusting the content ratio of the ethylene-derived structural unit to the propylene-derived structural unit. For example, when the ratio of the structural units derived from ethylene is increased, there is a tendency that the chemical resistance and crystallinity (and thus mechanical strength) of the rubber are increased. On the other hand, when the ratio of the structural units derived from ethylene is decreased, the moldability and flowability of the rubber tend to be decreased. In order to produce a molded article (seal) having better processability and high quality by injection molding, the flowability of the rubber component used is preferably relatively low.

From such a viewpoint, the content of the ethylene-derived structural unit in the EPDM is usually 70% by mass or less, preferably 55% by mass or less, and more preferably 51% by mass or less. When the content of the structural unit derived from ethylene is in the above range, EPDM can be imparted with good fluidity and a seal can be imparted with good low-temperature properties.

On the other hand, when the content of the structural unit derived from ethylene is excessively low, the tensile strength of the resulting seal is insufficient. Therefore, the content of the ethylene-derived structural unit in the EPDM is usually 40 mass% or more, preferably 45 mass% or more, and more preferably 48 mass% or more.

Specific examples of the diene monomer constituting the EPDM include: non-conjugated diene monomers such as 5-ethylidene-2-norbornene (ENB), dicyclopentadiene (DCPD), 1, 4-hexadiene (1, 4-HD), methyltetrahydroindene, 5-methylene-2-norbornene, cyclooctadiene, and bicyclooctadiene. Among them, ENB and 1, 4-HD are preferably used in view of the fact that EPDM exhibits a good crosslinking rate (vulcanization rate) and the heat resistance of the resulting sealing material is also excellent, and ENB is more preferably used in view of the fact that the crosslinking rate is particularly excellent. As the diene monomer, only one kind of monomer may be used, or two or more kinds of monomers may be used in combination.

The content of the structural unit derived from a diene monomer in the EPDM is usually 1 mass% or more, and preferably 2.5 mass% or more, from the viewpoint of improving the crosslinking rate and the moldability of the rubber composition. In addition, in view of the ease of deterioration of the seal material due to a large amount of double bonds remaining after crosslinking, the content of the structural unit derived from the diene monomer in the EPDM is usually 14 mass% or less, preferably 10 mass% or less, and more preferably 5.0 mass% or less.

The rubber component used in the rubber composition for a sealer is measured in accordance with JIS K6300-1: the Mooney viscosity [ ML (1+4)125 ℃ C. ] at 125 ℃ measured in 2013 is preferably 90 or less, more preferably 85 or less. The Mooney viscosity [ ML (1+4)125 ℃ C ] of the rubber component is preferably 40 or more, more preferably 50 or more, and still more preferably 75 or more. When the Mooney viscosity is too high, the processability is sometimes poor.

The rubber component used in the rubber composition for a sealer is measured in accordance with JIS K6300-1: the Mooney viscosity [ ML (1+4)100 ℃ C. ] at 100 ℃ measured in 2013 is preferably 60 or less, more preferably 50 or less. The Mooney viscosity [ ML (1+4)100 ℃ C ] of the rubber component is preferably 30 or more, more preferably 35 or more, and still more preferably 40 or more.

Preferably, EPDM is a rubber composition according to JIS K6300-1: 2013, or 30 to 60 at 100 ℃, and the EPDM contains 45 to 55 mass% of structural units derived from ethylene. When the EPDM is used as the rubber component, a seal excellent in followability in a lower temperature environment can be obtained. Such a seal does not cause leakage of high-pressure gas at-40 ℃ even without using grease. Since the use environment of a seal which is grease-free and has good sealing properties is not limited, the seal has high versatility, and a failure at the time of maintenance (replacement of the seal, etc.) is also reduced. Furthermore, such seals are capable of sealing high pressure gases even at temperatures of-45 ℃.

Specific examples of commercially available products of EPDM include "EPT" manufactured by Mitsui chemical Co., Ltd, "ESPRENE" manufactured by Sumitomo chemical Co., Ltd, "EP" manufactured by JSR, and "KELTAN" manufactured by LANXESS. Preferably, "ESPRENE 5361" or "ESPRENE 501A" manufactured by sumitomo chemical corporation and having excellent low-temperature recovery properties can be used.

[ B ] silica

The sealing member composition is highly filled with silica. Since hydrogen hardly enters the interior of the seal material due to the high silica content, the blister resistance of the seal material can be improved. Silica has lower hydrogen adsorption than carbon black and is therefore more useful for improving blister resistance.

As the silica, silica generally used as a filler which exerts a reinforcing effect in general-purpose rubbers can be used. The silica is not particularly limited, and includes: dry white carbon manufactured by a thermal decomposition method of halogenated silicic acid or an organic silicon compound, a method of oxidizing SiO air gasified by heating and reducing silica sand, or the like; wet white carbon produced by a sodium thermal decomposition method or the like. Dry white carbon is preferably used as silica. As the silica, only one kind of silica may be used, or two or more kinds of silica may be used in combination.

The silica contains at least 70 mass% of a silica component (SiO)₂). The specific surface area of the silicon dioxide is preferably 10-120 m²A concentration of 15 to 40m²/g。

The silica is preferably spherical. Conventionally, there has been an upper limit to the amount of silica that can be blended in a rubber composition for a seal, and it has been difficult to highly fill silica. However, when the silica is spherical, the silica is less rubbed against each other and the dispersibility is improved as compared with silica having other shapes (for example, chain-like), and therefore, the silica can be highly filled in the rubber composition for a seal. Further, when a large amount of silica is contained, the low temperature property of the sealing material may be lowered, but if the silica is spherical, the lowering of the low temperature property is less likely to occur. Therefore, both the blister resistance and the low temperature property of the seal member can be more easily achieved. It should be noted that the "spherical shape" includes not only a true ball but also a somewhat deformed ball.

The average particle diameter of the silica is preferably 5nm to 5 μm, more preferably 10nm to 1 μm, and still more preferably 50nm to 200nm, from the viewpoints of inhibition of aggregation and smoothness. When the average particle diameter of silica is too large, blister resistance and low temperature resistance of the seal member may be reduced. The average particle diameter can be determined, for example, as follows: morphological observation was performed using a microscope, and the particle diameter of silica in the observation field was measured by image analysis, and the average of the measured values was calculated.

The content of silica in the rubber composition for a sealing member is 50 to 140 parts by mass, preferably 80 to 140 parts by mass, per 100 parts by mass of the rubber component. When the content of silica is excessive, the low temperature property of the sealing member may be reduced.

[ C ] silane coupling agent

The rubber composition for a sealer contains a silane coupling agent for highly filling silica. The silane coupling agent has a reactive group chemically bonded to the inorganic material and a reactive group chemically bonded to the organic material in a molecule, and thus functions as a binder for connecting the inorganic material and the organic material, which are generally difficult to bond. When the surface of silica is coated with a silane coupling agent, the surface of silica becomes hydrophobic, and the aggregation of silica can be prevented. This makes it possible to fill the rubber composition for a sealing material with silica in a highly dispersed state, thereby improving the blister resistance of the sealing material. Further, the silane coupling agent increases the bonding force between the silica and the rubber component, thereby also improving the blistering resistance.

The silane coupling agent is not particularly limited, and examples thereof include: vinyl, acrylic, epoxy, mercapto, amino silane coupling agents, and the like.

Examples of the vinyl silane coupling agent include vinyltrichlorosilane, vinyltrimethoxysilane, and vinyltriethoxysilane. Examples of the acrylic silane coupling agent include 3-acryloxypropyltrimethoxysilane. Examples of the epoxy silane coupling agent include 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane. Examples of the methacrylic silane coupling agent include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane. These silane coupling agents may be used alone or in combination of two or more.

The content of the silane coupling agent in the rubber composition for a sealing member is 1 to 20 parts by mass, preferably 1 to 10 parts by mass, per 100 parts by mass of the rubber component. The foaming resistance of the rubber composition for a sealing material is improved by containing a larger amount of the silane coupling agent than before. However, when the silane coupling agent is too much, the elongation is extremely reduced, and therefore, there is a possibility that the product may be broken or the low-temperature property may be reduced during use.

[ D ] carbon Black

The rubber composition for a seal contains carbon black. By containing carbon black, the strength and blister resistance of the seal member can be improved.

The content of the carbon black is 15 to 35 parts by mass per 100 parts by mass of the rubber component. From the viewpoint of maintaining the co-crosslinking agent, the content of carbon black is preferably 20 parts by mass or more per 100 parts by mass of the rubber component. However, since carbon black adsorbs hydrogen, when a large amount of carbon black is blended, the blister resistance may be lowered. The total content of silica and carbon black is preferably 95 to 140 parts by mass per 100 parts by mass of the rubber component. The foaming resistance is improved by highly filling a filler such as silica or carbon black, but when the amount of the filler is too large, the rigidity of the seal is too high, and the low temperature property may be lowered.

Further, the carbon black is preferably spherical. When the carbon black is closer to a true sphere (a small specific surface area), the carbon black is less likely to aggregate, and the low-temperature property of the rubber composition for a gasket is less likely to decrease. From the viewpoint of reinforcement, the particle size of carbon black is preferably small.

Carbon black may be either conductive or nonconductive, and the following are prepared: furnace black, channel black, acetylene black, ketjen black, thermal black, lamp black, and the like. The carbon black may be used singly or in combination of two or more.

As carbon black, for example, SAF, ISAF-HF, ISAF-LS, IISAF-HS, HAF-HS, HAF-LS, MAF, FEF-LS, GPF-HS, GPF-LS, SRF-HS, SRF-LM, FT, MT and the like can be used. Two or more carbon blacks having different particle diameters may be used.

The average particle diameter of carbon black may vary depending on the manufacturing company, but for example, SAF is 19nm, ISAF is 23nm, HAF is 28nm, MAF is 38nm, FEF is 43nm, GPF is 62nm, SRF is 66nm, and FT is 122 nm.

[ E ] Co-crosslinking agent

The rubber composition for a sealer preferably further contains a co-crosslinking agent. Examples of the co-crosslinking agent include: quinone dioxime, ethylene glycol dimethacrylate, divinylbenzene, diallyl phthalate, triallyl isocyanurate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, 1, 2-polybutadiene, metal methacrylate, metal acrylate, and the like. As the co-crosslinking agent, only one kind of co-crosslinking agent may be used, or two or more kinds of co-crosslinking agents may be used in combination.

The content of the co-crosslinking agent in the rubber composition for a sealing material is preferably 1 to 20 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of the rubber component. Within this range, the flowability and processability of the rubber composition for a sealing material can be improved. Within this range, the blister resistance of the crosslinked sealing material can be further improved. When the content of the co-crosslinking agent is too small, the 100% tensile stress of the seal material may be reduced, and when the content of the co-crosslinking agent is too large, the elongation at the time of cutting may be less than 100%, and the low temperature property may be reduced.

Other component (F)

The rubber composition for a gasket may contain other components than the above components as required. Examples of other components to be contained include: fillers other than silica and carbon black (including extender pigments and coloring pigments), surfactants other than silane coupling agents, anti-aging agents, vulcanization accelerators, antioxidants, processing aids (stearic acid and the like), vulcanization aids (zinc oxide and the like), stabilizers, tackifiers, polyols, flame retardants, waxes, lubricants and other additives. As the additive, only one kind of additive may be used, or two or more kinds of additives may be used in combination.

When the rubber composition for a sealing material contains the above-mentioned additives, the content thereof may be an amount generally used in this field.

Examples of the filler include: alumina, zinc oxide, titanium dioxide, clay, talc, diatomaceous earth, barium sulfate, calcium carbonate, magnesium carbonate, calcium oxide, mica, graphite, aluminum hydroxide, aluminum silicate, hydrotalcite, granular or powdery resin, metal powder, glass powder, ceramic powder, and the like.

Examples of the antioxidant include: phenol derivatives, aromatic amine derivatives, amine-ketone condensates, benzimidazole derivatives, dithiocarbamic acid derivatives, thiourea derivatives, and the like.

Examples of the vulcanization accelerator include: thiuram, thiazole, sulfenamide, thiourea, guanidine, dithiocarbamate compounds, and the like.

Examples of the processing aid include thermoplastic resins, liquid rubbers, oils, softeners, internal mold release agents, and tackifiers. For example, in the case where the rubber component is FKM or FFKM, the filler may contain a fluororesin or its particles, and the processing aid may contain a liquid fluororubber. For example, when the rubber component is EPM or EPDM, paraffin oil may be contained as the processing aid. The content of the processing aid is preferably 0.5 to 5 parts by mass, and more preferably 1.0 to 2.5 parts by mass, per 100 parts by mass of the rubber composition for a sealing member.

Examples of the internal mold release agent include higher fatty acids, fatty acid esters, fatty acid amides, fluorine resins, silicone resins, and hydrocarbon resins. From the viewpoint of improving the low-temperature properties, the content of the internal mold release agent is preferably 0.5 to 5 parts by mass, and more preferably 1.0 to 2.5 parts by mass, per 100 parts by mass of the rubber composition for a sealing material. When the content of the internal mold release agent is less than 0.5 part by mass, the mold release effect is small, because there is a risk that the mold is contaminated by adhesion of rubber to the mold. Further, the rubber composition for a seal can improve the low temperature property without lowering the blister resistance by containing an internal mold release agent having a high viscosity.

Examples of the surfactant other than the silane coupling agent include nonionic surfactants, and examples of the nonionic surfactant include higher alcohols and polyhydric alcohols. Specific examples of the polyol include diethylene glycol. In the case of containing a polyol, the hydroxyl group of the silica is suppressed, and the dispersibility and strength of the silica are improved.

As the crosslinking agent, sulfur, an organic sulfur compound, a disulfide, an organic peroxide, or the like can be used. Examples of the organic peroxide used in EPDM and H-NBR include 2, 5-dimethyl-2, 5-di-tert-butyl-hexane-peroxide-3, di-tert-butyl peroxide, 2, 5-dimethyl-2, 5-di-tert-butyl-hexane peroxide, tert-butylcumyl peroxide, 1, 3-bis (tert-butylperoxy-isopropyl) benzene, dicumyl peroxide, 4-di-tert-butylperoxy-butyl valerate, 2-di-tert-butylperoxy-butane, 1-di-tert-butylperoxy-3, 3, 5-trimethylcyclohexane, dibenzoyl peroxide, di (o-methylbenzoyl) peroxide, di (p-methylbenzoyl) peroxide, and tert-butylperoxy-benzilate.

The content of the crosslinking agent in the rubber composition for a sealing material is usually 0.1 to 20 parts by mass, preferably 0.2 to 10 parts by mass, per 100 parts by mass of the rubber component. Within this range, the crosslinking reaction can be sufficiently advanced, and thus a cushioning material having excellent hardness, mechanical strength, compression set resistance, and the like, and excellent impact resistance can be obtained.

When the rubber composition for a sealing material contains an excessive amount of a filler in order to improve blistering resistance, the hardness tends to be increased, the elongation tends to be decreased, and the sealing material tends to become brittle. When a plasticizer is included, these properties are improved and the low temperature property becomes good. However, when a large amount of plasticizer is contained, the plasticizer component is likely to be deposited on the surface of the molded article, or the plasticizer component is likely to be extracted by a lubricant such as grease. As a result, the volume may be reduced, the low temperature and heat resistance may be reduced, and the sealing property may be reduced. From such a viewpoint, the rubber composition for a seal preferably does not contain a plasticizer.

[ method for producing sealing Material ]

The rubber composition for a sealing material can be prepared by uniformly kneading the above-mentioned components. As the kneading machine, conventionally known kneading machines such as a mixing roll (kneading roll), a pressure kneader (kneader), and an internal mixer (banbury mixer) can be used. In this case, components other than the components contributing to the crosslinking reaction (crosslinking accelerator, crosslinking retarder, crosslinking agent, etc.) among the compounding components may be uniformly kneaded in advance, and then the components contributing to the crosslinking reaction may be kneaded. The kneading temperature is, for example, around room temperature.

< seal >

The sealing material is formed from a crosslinked product of the rubber composition for sealing material. The sealing member can be produced by crosslinking (vulcanizing)/molding a rubber composition for a sealing member. The crosslinking/molding method may be a conventionally known method such as injection molding, compression molding, transfer molding, or the like.

The heating temperature (crosslinking temperature) during molding is, for example, about 100 to 200 ℃, and the heating time (crosslinking time) is, for example, about 0.5 to 120 minutes. When HNBR, EPDM, CR, FKM, VMQ are used as the rubber component, it is preferable to carry out vulcanization twice.

The seal may be a gasket (packing), washer (gasket), or the like. The shape of the seal member may be appropriately selected according to the purpose, and a representative example thereof is an O-ring having an O-shape in cross section. The sealing material is excellent in low temperature properties and blistering resistance, and therefore can be preferably used as a sealing material for a storage tank storing high-pressure hydrogen gas at 80MPa, for example. Further, as the high-pressure gas to be stored, not only hydrogen gas but also oxygen gas, nitrogen gas, helium gas, or the like can be preferably used.

Examples

The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[ evaluation of physical Properties of molded article ]

From JIS K6250: 2006A sheet-like sample for physical property evaluation having a thickness of 2mm was prepared, and the thickness was measured in accordance with JIS K6251: 2017, and demolding to obtain the dumbbell-shaped test piece with the size of No. 3. The test piece was stretched at 500 mm/min, and the tensile strength, elongation at cut and 100% tensile stress were measured using a Shopper type tensile tester. Further, according to JIS K6253: 2012, the hardness of the sheet-like sample for physical property evaluation was measured by a type a durometer hardness tester. All of these tests were carried out at a temperature of 25 ℃.

[ high temperature high pressure cycle test of sealing Member ]

The sealing test sample molded into the O-ring was placed on the flange, and a cycle test was performed under the conditions shown in table 1 to evaluate the blistering resistance. After the cycle test, the cross section of the O-ring was observed, and the seal in which breakage was observed was evaluated as "B", and the seal in which no crack was observed was evaluated as "a". Further, the presence or absence of air leakage was detected under the conditions shown in table 1. The seal in which air leakage was detected was evaluated as "B", and the seal in which air leakage was not detected was evaluated as "a".

[ Table 1]

Speed of boost	2MPa/s
		Speed of depressurization	100MPa/s
Highest pressure	100MPa
		Lowest pressure	0MPa
Maximum pressure maintenance	1s
		Minimum pressure maintenance	1s
Number of pressure cycles	50 times
		Temperature of	100℃
Test ofFluid, especially for a motor vehicle	Helium gas

[ Low temperature high pressure cycle test of sealing Member ]

The sealing test sample molded into the O-ring was placed on the flange, and a cycle test was performed under the conditions shown in table 2. After the test, the cross section of the O-ring was observed, and the seal in which breakage was observed was evaluated as "B", and the seal in which no crack was observed was evaluated as "a". Further, the presence or absence of air leakage was detected under the conditions shown in table 2. The test was carried out with or without applying grease (silicone grease, KF-96H-100 ten thousand cSt, manufactured by shin-Etsu chemical Co., Ltd.) to the seal portion. The seal in which air leakage was detected was evaluated as "B", and the seal in which air leakage was not observed was evaluated as "a".

[ Table 2]

Speed of boost	100MPa/s
		Speed of depressurization	100MPa/s
Highest pressure	100MPa
		Lowest pressure	0MPa
Maximum pressure maintenance	1s
		Minimum pressure maintenance	1s
Number of pressure cycles	50 times
		Temperature of	-40℃
Test fluid	Helium gas

[ preparation of rubber composition for sealing Material and production of molded article ]

The respective components described in table 3 were kneaded in a 10L pressure kneader to prepare rubber compositions for a gasket of examples and comparative examples. The obtained rubber composition for a sealing member is put into a mold heated to 160 to 180 ℃, and molded by pressing under pressure. The molding time is 5-20 minutes. Further, secondary vulcanization is carried out at 160 to 180 ℃ for 0.5 to 2 hours to obtain a sample for physical property evaluation and a sample for a seal test.

The normal physical properties of the physical property evaluation sample were measured according to the above evaluation methods. The above cycle test was carried out to evaluate the sealability of the sealing test sample at high and low temperatures. The results are shown in Table 3.

[ Table 3]

Details of the complexes in table 3 are as follows. The unit of the amount blended in the table is part by mass.

[1] rubber component A: ESPRENE 5361 (manufactured by Sumitomo chemical industries, Ltd., EPDM: a structural unit derived from ethylene 49% by mass, a structural unit derived from 5-ethylidene-2-norbornene (ENB) as a diene monomer 3.5% by mass, and Mooney viscosity at 125 [ [ ML (1+4)125 ℃ ] ] measured according to JIS K6300-1 83.)

[2] rubber component B: ESPRENE 501A (manufactured by Sumitomo chemical industries, Ltd., EPDM: a structural unit derived from ethylene 52% by mass, a structural unit derived from 5-ethylidene-2-norbornene (ENB) as a diene monomer 4.0% by mass, and Mooney viscosity at 100 [ [ ML (1+4)100 ℃ ] ] measured according to JIS K6300-1 of 44.)

[3] vulcanization assistant: two kinds of zinc oxide (HAKUSUI TECH products of Kabushiki Kaisha)

[4] antiaging agent: nocrac 224S (2, 2, 4-trimethyl-1, 2-dihydroquinoline copolymer, available from Dainixing chemical industries Co., Ltd.)

[5] processing aid: LUNAC S50V (stearic acid, King of flower Co., Ltd.)

[6] carbon Black: seast GSO (furnace black manufactured by TOKAI CARBON)

[7] silica: sidistar (manufactured by Elkem, spherical silica, BET surface area 20 m)²(g) CTAB adsorption specific surface area 30m²(g), DBP absorption 85g/100g, average particle diameter 150nm)

[ 8 ] silane coupling agent: KBM1003 (manufactured by shin-Etsu chemical Co., Ltd., vinyltrimethoxysilane)

[ 9 ] polyol: diethylene glycol (manufactured by Japan catalyst of Kabushiki Kaisha)

[ 10 ] Co-crosslinking agent: HiCross M (manufactured by Seiko chemical Co., Ltd., trimethylolpropane trimethacrylate)

[ 11 ] crosslinking agent A: sulfur (Crane, chemical Co., Ltd., colloidal sulfur)

[ 12 ] crosslinking agent B: perkadox 14-40 (chemical Akzo Co., Ltd., bis (tert-butylperoxyisopropyl) benzene 40% dilution, organic peroxide)

As shown in Table 3, the seal test samples of examples 1 to 3 obtained by crosslinking the rubber composition for a seal material, which comprises 50 to 140 parts by mass of silica, 1 to 20 parts by mass of a silane coupling agent, and 15 to 35 parts by mass of carbon black based on 100 parts by mass of the rubber component, exhibited no cracks in the cross section of the sample even when exposed to a high-temperature and high-pressure environment, and exhibited excellent blister resistance. Further, since no leakage was observed under a high-temperature and high-pressure environment, the samples for the sealing test of examples 1 to 3 were found to have excellent sealing properties at high temperatures. When the sealing test samples of examples 1 to 3 were tested by applying grease under a low-temperature high-pressure environment, no leakage was observed, and the sealing property at low temperature was excellent. Further, it can be seen that: in the sealing test sample of example 1 using EPDM having more excellent cold resistance, no air leakage was observed even when the grease was not applied at a temperature of-40 ℃, and a sealing material having more excellent low temperature properties than those of examples 2 and 3 was obtained.

On the other hand, the samples for physical property evaluation of comparative examples 1, 2 and 4 had lower 100% tensile stress than those of examples 1 and 2, and the sealing test samples thereof had blisters in the high temperature and high pressure cycle test. The hardness of the sample for physical property evaluation of comparative example 3 increased, the tensile strength and the elongation at cutting decreased, and the sealing test sample thereof was foamed in the high-temperature high-pressure cycle test and also decreased in the low-temperature property.

[ reference example ]

Rubber compositions for a sealing material of reference examples 1 and 2 were prepared in the same manner as in example 1 and in accordance with Table 4, and samples for evaluating physical properties were obtained. The normal physical properties of the physical property evaluation sample were measured according to the above evaluation methods. The results are shown in Table 4.

[ Table 4]

Details of the complexes in table 4 are as follows. The unit of the amount blended in the table is part by mass.

[1] rubber component B: ESPRENE 501A (manufactured by Sumitomo chemical industries, Ltd., EPDM: a structural unit derived from ethylene 52% by mass, a structural unit derived from 5-ethylidene-2-norbornene (ENB) as a diene monomer 4.0% by mass, and Mooney viscosity at 100 [ [ ML (1+4)100 ℃ ] ] measured according to JIS K6300-1 of 44.)

[2] vulcanization assistant: two kinds of zinc oxide (HAKUSUI TECH products of Kabushiki Kaisha)

[3] antiaging agent: nocrac 224S (2, 2, 4-trimethyl-1, 2-dihydroquinoline copolymer, available from Dainixing chemical industries Co., Ltd.)

[4] processing aid: LUNAC S50V (stearic acid, King of flower Co., Ltd.)

[5] carbon Black: seast GSO (furnace black manufactured by TOKAI CARBON)

[6] silica A: sidistar (manufactured by Elkem, spherical silica, BET surface area 20 m)²(g) CTAB adsorption specific surface area 30m²(g), DBP absorption 85g/100g, average particle diameter 150nm)

[7] silica B: AEROSIL 200 (BET surface area 200m, manufactured by AEROSIL, Japan)²(ii)/g, hydrophilic fumed silica, average particle diameter 7 to 40nm)

[ 8 ] silane coupling agent: KBM1003 (manufactured by shin-Etsu chemical Co., Ltd., vinyltrimethoxysilane)

[ 9 ] polyol: diethylene glycol (manufactured by Japan catalyst of Kabushiki Kaisha)

[ 10 ] Co-crosslinking agent A: HiCross M (manufactured by Seiko chemical Co., Ltd., trimethylolpropane trimethacrylate)

[ 11 ] Co-crosslinking agent B: TAIC (triallyl isocyanurate manufactured by Nippon Kasei Co., Ltd.)

[ 12 ] crosslinking agent A: sulfur (Crane, chemical Co., Ltd., colloidal sulfur)

[ 13 ] crosslinking agent B: perkadox 14-40 (chemical Akzo Co., Ltd., bis (tert-butylperoxyisopropyl) benzene 40% dilution, organic peroxide)

The sample for physical property evaluation of reference example 1 containing silica B in place of silica A had an increased hardness, a decreased tensile strength and elongation at break, and a lower blister resistance than those of example 2. Further, the sample for physical property evaluation of reference example 2 containing the co-crosslinking agent B in place of the co-crosslinking agent A was expected to have a reduced 100% tensile stress and inferior blister resistance and low temperature properties as compared with example 2.