Functional rubber component

Abstract

To provide a functional rubber component that exhibits superior operability in reciprocating motion and sealability in reciprocating motion under a low-temperature environment without causing deterioration in mechanical strength and elongation properties at room temperature.SOLUTION: A functional rubber component is formed from a rubber composition comprising an oil-extended ethylene-butene-diene rubber having an ethylene content of 42 mass% or more and 59 mass% or less and a diene content of 2.0 mass% or more and 13 mass% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a functional rubber part, and more particularly to a functional rubber part that has excellent properties in a low-temperature environment without impairing mechanical strength and elongation properties at room temperature. [Background technology]

[0002] Automobiles and other devices are sometimes equipped with rubber parts that undergo reciprocating motion, such as release valves, check valves, diaphragm pumps, etc. Furthermore, because automobiles and other devices may be used not only in warm regions but also in cold regions, rubber parts that undergo reciprocating motion and are installed in automobiles and other devices are required to maintain their reciprocating motion and sealing properties even in low-temperature environments.

[0003] However, materials that have traditionally been used for rubber parts, such as ethylene propylene diene rubber, acrylonitrile-butadiene copolymer rubber, hydrogenated nitrile rubber, and fluororubber, have problems in that, for example, the balance between elongation and strength deteriorates in low-temperature environments, resulting in a decline in the properties required for rubber parts, such as reciprocating motion operability and sealing ability.

[0004] Therefore, a rubber composition has been proposed in which 2.5 to 7.5 parts by mass of an ethylene-α-olefin copolymer having a melting point of 100°C or higher and a glass transition temperature of -55°C or lower is used per 100 parts by mass of ethylene-butene-diene copolymer rubber (Patent Document 1).The rubber composition in Patent Document 1 claims that adding a predetermined amount of hydrocarbon polymer oil to the ethylene-butene-diene copolymer rubber makes it possible to obtain rubber parts with excellent sealing properties in low-temperature environments.

[0005] However, rubber parts molded from the rubber composition containing the hydrocarbon polymer oil of Patent Document 1 still exhibit reduced properties required of rubber parts, such as reciprocating motion operability and sealing performance during reciprocating motion, in extremely low-temperature environments such as -40°C, and there was a need to improve low-temperature properties. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2019 / 216311 Summary of the Invention [Problem to be solved by the invention]

[0007] In view of the above circumstances, an object of the present invention is to provide a functional rubber part that has excellent reciprocating motion operability and sealing properties in a low-temperature environment without compromising mechanical strength and elongation characteristics at room temperature. [Means for solving the problem]

[0008] The gist of the configuration of the functional rubber part of the present invention is as follows. [1] A functional rubber part molded from a rubber composition containing oil-extended ethylene butene diene rubber having an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less. [2] The functional rubber part according to [1], which is used as a check valve, an elastic diaphragm, a bellows, or a sealing member. [3] The functional rubber part according to [2], wherein the check valve is an umbrella valve. [4] The functional rubber part according to [2], wherein the elastic diaphragm is a diaphragm of a diaphragm pump. [5] The functional rubber part according to [2], wherein the sealing member is an O-ring. [6] The functional rubber part according to [1], wherein the rubber composition further contains non-oil-extended ethylene butene diene rubber. [7] The functional rubber part according to [6], wherein the non-oil-extended ethylene butene diene rubber has an ethylene content of 42% by mass or more and 59% by mass or less, and a diene content of 2.0% by mass or more and 13% by mass or less. [8] A functional rubber part according to [6] or [7], containing 1.0 part by mass or more and 2500 parts by mass or less of the non-oil-extended ethylene butene diene rubber per 100 parts by mass of the rubber component of the oil-extended ethylene butene diene rubber. [9] The functional rubber part according to [1], wherein the rubber composition further contains carbon black.

[10] The functional rubber part according to [1], wherein the rubber composition further contains 10 parts by mass or more and 100 parts by mass or less of carbon black per 100 parts by mass of the rubber component of the oil-extended ethylene butene diene rubber.

[11] The functional rubber part according to [6] or [7], further comprising 10 parts by mass or more and 80 parts by mass or less of carbon black per 100 parts by mass of the rubber component of the oil-extended ethylene butene diene rubber and the non-oil-extended ethylene butene diene rubber.

[12] The functional rubber part according to [9], wherein the carbon black has an arithmetic mean particle size of 20 nm or more and 50 nm or less. [Effects of the Invention]

[0009] According to an embodiment of the functional rubber part of the present invention, the functional rubber part is molded from a rubber composition containing oil-extended ethylene butene diene rubber having an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less. This makes it possible to obtain a functional rubber part that has excellent reciprocating motion operability and sealing ability during reciprocating motion in low-temperature environments without compromising mechanical strength and elongation properties in room-temperature environments.

[0010] According to an aspect of the functional rubber part of the present invention, when the part is used as a check valve, an elastic diaphragm, a bellows, or a sealing member, it is possible to obtain a check valve, an elastic diaphragm, a bellows, or a sealing member that has excellent reciprocating motion operability and sealing property in a low-temperature environment without compromising the mechanical strength and elongation characteristics in a room-temperature environment.

[0011] According to an aspect of the functional rubber part of the present invention, the check valve is an umbrella valve, so that an umbrella valve having excellent reciprocating motion operability and sealing properties in a low-temperature environment can be obtained without compromising the mechanical strength and elongation characteristics in a room-temperature environment.

[0012] According to an aspect of the functional rubber part of the present invention, the rubber composition further contains non-oil-extended ethylene butene diene rubber, whereby a functional rubber part can be obtained in which the operability during reciprocating motion and the sealing property during reciprocating motion in a low-temperature environment are reliably improved.

[0013] According to an embodiment of the functional rubber part of the present invention, the ethylene content of the un-oil-extended ethylene butene diene rubber is 42% by mass or more and 59% by mass or less, and the diene content is 2.0% by mass or more and 13% by mass or less, thereby making it possible to obtain a functional rubber part with further improved reciprocating motion operability and sealing performance during reciprocating motion in low-temperature environments.

[0014] According to an embodiment of the functional rubber part of the present invention, by containing 1.0 part by mass or more and 2500 parts by mass or less of the non-oil-extended ethylene butene diene rubber per 100 parts by mass of the rubber component of the oil-extended ethylene butene diene rubber, it is possible to obtain a functional rubber part with more reliably improved operability in reciprocating motion and sealing performance during reciprocating motion in a low-temperature environment.

[0015] According to an aspect of the functional rubber part of the present invention, the rubber composition further contains carbon black, so that mechanical strength in a room temperature environment can be more reliably obtained.

[0016] According to an aspect of the functional rubber part of the present invention, the rubber composition further contains 10 parts by mass or more and 100 parts by mass or less of carbon black per 100 parts by mass of the oil-extended ethylene butene diene rubber rubber component, thereby making it possible to more reliably obtain mechanical strength in a room temperature environment.

[0017] According to one aspect of the functional rubber part of the present invention, the rubber component further contains 10 parts by mass or more and 80 parts by mass or less of carbon black relative to a total of 100 parts by mass of the rubber component of the oil-extended ethylene butene diene rubber and the non-oil-extended ethylene butene diene rubber. This reliably improves the operability and sealing performance during reciprocating motion in low-temperature environments, while also more reliably achieving mechanical strength in room-temperature environments.

[0018] According to one aspect of the functional rubber part of the present invention, the arithmetic mean particle diameter of the carbon black is 20 nm or more and 50 nm or less, which reliably improves the operability of reciprocating motion and the sealing performance during reciprocating motion in a low-temperature environment, while more reliably obtaining mechanical strength in a room-temperature environment. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view of an umbrella valve, which is a functional rubber part of the present invention. [Figure 2] FIG. 1 is a side view of an umbrella valve, which is a functional rubber part of the present invention. [Figure 3] 1 is a side cross-sectional view showing a check valve device for an air pump equipped with an umbrella valve, which is a functional rubber part of the present invention. [Figure 4] 1 is a side cross-sectional view showing an open state of a check valve device for an air pump equipped with an umbrella valve, which is a functional rubber part of the present invention. [Figure 5] 1 is an enlarged side cross-sectional view showing an open state of a check valve device for an air pump equipped with an umbrella valve, which is a functional rubber part of the present invention. FIG. [Figure 6] 1 is a side cross-sectional view showing a check valve device for an air pump equipped with an umbrella valve, which is a functional rubber part of the present invention, in a closed state. [Figure 7] FIG. 10 is a side cross-sectional view showing another embodiment of an umbrella valve that is a functional rubber part of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The functional rubber part of the present invention will be described in detail below.

[0021] The functional rubber part of the present invention is molded from a rubber composition containing oil-extended ethylene butene diene rubber having an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less. According to an embodiment of the functional rubber part of the present invention, by molding from a rubber composition containing oil-extended ethylene butene diene rubber having an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less, it is possible to obtain a functional rubber part that has excellent reciprocating motion operability and sealing property in reciprocating motion in a low-temperature environment without impairing mechanical strength and elongation properties in a room-temperature environment.

[0022] The structure of the functional rubber part of the present invention will be described below. Here, the structure of the functional rubber part will be described using as an example a case where the functional rubber part is used as a check valve and the check valve is an umbrella valve. Note that Fig. 1 is a perspective view of an umbrella valve, which is a functional rubber part of the present invention. Fig. 2 is a side view of an umbrella valve, which is a functional rubber part of the present invention.

[0023] <Umbrella Valve> 1 and 2, umbrella valve 1, which is a functional rubber part of the present invention, has an umbrella-shaped portion 11 and a stem portion 13 extending vertically from a center portion 14 of umbrella-shaped portion 11. An expanded diameter portion 12 is formed in the middle of stem portion 13 to prevent umbrella valve 1 from coming off a check valve device equipped with umbrella valve 1.

[0024] The height T of the umbrella valve 1 is, for example, 5 mm to 20 mm, and preferably 7 mm to 17 mm. The diameter D of the umbrella-shaped portion 11 is, for example, 3 mm to 70 mm, and preferably 5.5 mm to 54 mm.

[0025] <Check valve device> Next, a check valve device equipped with an umbrella valve 1 will be described. Fig. 3 is a side cross-sectional view showing a check valve device for an air pump equipped with an umbrella valve, which is a functional rubber part of the present invention. Fig. 4 is a side cross-sectional view showing an open state of a check valve device for an air pump equipped with an umbrella valve, which is a functional rubber part of the present invention. Fig. 5 is a side cross-sectional view showing an enlarged open state of a check valve device for an air pump equipped with an umbrella valve, which is a functional rubber part of the present invention. Fig. 6 is a side cross-sectional view showing a closed state of a check valve device for an air pump equipped with an umbrella valve, which is a functional rubber part of the present invention.

[0026] 3, the check valve device 100 is installed between the pump space S1 and the exhaust chamber S2 and allows gas to flow only from the pump space S1 to the exhaust chamber S2. The check valve device 100 includes a partition wall 20 that separates the pump space S1 from the exhaust chamber S2, and an umbrella valve 1 provided on the partition wall 20.

[0027] The partition wall 20 has a plurality of flow path holes 21 formed therein, which communicate between the pump space S1 and the exhaust chamber S2. The diameter d of the flow path holes 21 is, for example, 0.5 mm to 22 mm, and preferably 0.5 mm to 16 mm. The number of flow path holes 21 provided may be, for example, 2 to 8. In addition, in order to increase the gas flow rate, the area of ​​the flow path holes 21 may be increased by connecting the plurality of flow path holes 21. The umbrella valve 1 is provided so that the umbrella-shaped portion 11 can close the flow path holes 21 formed in the partition wall 20.

[0028] As shown in Figures 4 and 5, when the pressure in the pump space S1 becomes higher than the pressure in the exhaust chamber S2 and the pressure difference reaches the set pressure, the umbrella-shaped portion 11 of the umbrella valve 1 moves away from the opening of the flow path hole 21 to enter the open state, and the gas in the pump space S1 flows into the exhaust chamber S2, ensuring a normal flow.

[0029] On the other hand, as shown in FIG. 6, when the pressure in the pump space S1 becomes lower than the pressure in the exhaust chamber S2, the umbrella-shaped portion 11 blocks the flow path hole 21, so that the gas in the exhaust chamber S2 does not flow (backflow) into the pump space S1.

[0030] The set pressure of the check valve device 100 is not particularly limited, and may be, for example, 0.1 KPa to 15 KPa.

[0031] When a check valve device is used in an extremely low temperature environment, such as -40°C, the properties required of rubber parts, such as the operability of the reciprocating motion of the umbrella valve (i.e., the operability of the repeated movement between the open and closed states) and the sealing property during reciprocating motion (sealing property when the valve is closed), are reduced, and there was a need to improve the low-temperature properties. Therefore, the functional rubber part of the present invention (umbrella valve 1 in Figures 1 to 6) is important in that, in the check valve device 100, it has excellent operability during reciprocating motion and sealing property during reciprocating motion in a low-temperature environment without compromising the mechanical strength and elongation properties at room temperature (e.g., 25°C).

[0032] 1 to 6, the umbrella valve 1 has a flat tip 15 of the umbrella-shaped portion 11, and is assembled to the check valve device 100 by press-fitting the tip 15 or by pulling the stem portion 13. Also, as shown in Fig. 7, instead of the umbrella valve 1 that is assembled to the check valve device 100 by press-fitting the tip 15 or by pulling the stem portion 13, an umbrella valve 2 may be used in which a hole 16 is formed in the tip 15 of the umbrella-shaped portion 11 and the hole 16 is pressed to assemble it to the check valve device 100. Fig. 7 is a side cross-sectional view showing another embodiment of an umbrella valve that is a functional rubber part of the present invention.

[0033] According to an embodiment of the functional rubber part of the present invention, the check valve is molded from a rubber composition containing an oil-extended ethylene butene diene rubber having an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less, so that a check valve having excellent reciprocating operability and sealing ability during reciprocating motion in a low-temperature environment can be obtained without compromising the mechanical strength and elongation characteristics in a room-temperature environment.Furthermore, when the check valve is an umbrella valve 1 or 2, the umbrella valve 1 or 2 having excellent reciprocating operability and sealing ability during reciprocating motion in a low-temperature environment can be obtained without compromising the mechanical strength and elongation characteristics in a room-temperature environment.

[0034] The functional rubber part of the present invention can also be used as a duckbill check valve. By using a duckbill as the check valve, it is possible to obtain a duckbill that has excellent reciprocating motion operability and sealing properties in a low-temperature environment without compromising the mechanical strength and elongation characteristics in a room-temperature environment.

[0035] The functional rubber part of the present invention may also be used as an elastic diaphragm, such as a diaphragm for a diaphragm pump.

[0036] According to an embodiment of the functional rubber part of the present invention, the elastic diaphragm is molded from a rubber composition containing an oil-extended ethylene butene diene rubber having an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less, so that an elastic diaphragm having excellent reciprocating motion operability and sealing ability during reciprocating motion in a low-temperature environment can be obtained without compromising the mechanical strength and elongation properties at room temperature.Furthermore, when the elastic diaphragm is the diaphragm of a diaphragm pump, a diaphragm having excellent reciprocating motion operability and sealing ability during reciprocating motion in a low-temperature environment can be obtained without compromising the mechanical strength and elongation properties at room temperature.

[0037] The functional rubber part of the present invention may also be used as a bellows (bellows). According to one aspect of the functional rubber part of the present invention, the bellows is molded from a rubber composition containing an oil-extended ethylene butene diene rubber having an ethylene content of 42% by mass to 59% by mass and a diene content of 2.0% by mass to 13% by mass, thereby providing a bellows with excellent sealing properties in low-temperature environments without sacrificing mechanical strength and elongation properties in room-temperature environments. The functional rubber part of the present invention may also be used as a sealing member such as an O-ring. According to one aspect of the functional rubber part of the present invention, the O-ring is molded from a rubber composition containing an oil-extended ethylene butene diene rubber having an ethylene content of 42% by mass to 59% by mass and a diene content of 2.0% by mass to 13% by mass, thereby providing a sealing member such as an O-ring with excellent sealing properties in low-temperature environments without sacrificing mechanical strength and elongation properties in room-temperature environments.

[0038] Hereinafter, each component of the rubber composition, which is the raw material for the functional rubber part of the present invention, will be described in detail.

[0039] <Oil-extended ethylene butene diene rubber (oil-extended EBDM)> The rubber composition, which is the raw material for the functional rubber part of the present invention, contains an oil-extended ethylene butene diene rubber having an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less. That is, the rubber component of the oil-extended ethylene butene diene rubber is an ethylene butene diene rubber having an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less.

[0040] The ethylene content of the ethylene butenediene rubber is not particularly limited as long as it is in the range of 42% by mass or more and 59% by mass or less, but the lower limit is preferably 45% by mass, and particularly preferably 47% by mass, from the viewpoint of reliably improving the reciprocating motion operability and sealing performance in low-temperature environments while maintaining the mechanical strength and elongation properties of the functional rubber part of the present invention at room temperature. On the other hand, the upper limit of the ethylene content of the ethylene butenediene rubber is preferably 57% by mass, and particularly preferably 55% by mass, from the viewpoint of reliably improving the reciprocating motion operability and sealing performance in low-temperature environments while maintaining the mechanical strength and elongation properties of the functional rubber part of the present invention at room temperature.

[0041] The diene content of the ethylene butene diene rubber is not particularly limited as long as it is in the range of 2.0% by mass or more and 13% by mass or less. However, from the viewpoint of reliably improving the reciprocating motion operability and sealing performance of the functional rubber part of the present invention in a low-temperature environment, the diene content is preferably 2.5% by mass or more and 10% by mass or less, and particularly preferably 3.0% by mass or more and 8.0% by mass or less.

[0042] The amount of oil extension (phr) of the oil-extended ethylene butene diene rubber is not particularly limited, but from the viewpoint of reliably improving the operability of the functional rubber part of the present invention in reciprocating motion and the sealing performance during reciprocating motion in a low-temperature environment while obtaining the mechanical strength and elongation characteristics in a room temperature environment, the amount of oil extension is preferably 10 parts by mass or more and 50 parts by mass or less, and particularly preferably 20 parts by mass or more and 40 parts by mass or less, per 100 parts by mass of the ethylene butene diene rubber.

[0043] Mooney viscosity (ML) of oil-extended ethylene butene diene rubber 1+4 , 125°C) is not particularly limited, but the lower limit is preferably 30, and particularly preferably 40, from the viewpoint of reliably improving the mechanical strength and elongation properties of the functional rubber part of the present invention under a room temperature environment. On the other hand, the Mooney viscosity (ML 1+4 , 125°C) is preferably 65, particularly preferably 55, from the viewpoint of processability when molding the functional rubber part of the present invention from the rubber composition. 1+4, 125°C) are values ​​measured in accordance with JIS K-6300-1.

[0044] Examples of the oil type of the oil component of the oil-extended ethylene butene diene rubber include mineral oil.

[0045] <Non-oil-extended ethylene butene diene rubber (non-oil-extended EBDM)> The rubber composition, which is the raw material for the functional rubber part of the present invention, may further contain non-oil-extended ethylene butene diene rubber in addition to the oil-extended ethylene butene diene rubber, as necessary. By including the non-oil-extended ethylene butene diene rubber, it is possible to obtain a functional rubber part that reliably improves the operability and sealing performance during reciprocating motion in a low-temperature environment.

[0046] The ethylene content of the non-oil-extended ethylene butenediene rubber is not particularly limited, but the lower limit is preferably 42% by mass, more preferably 45% by mass, and particularly preferably 47% by mass, from the viewpoint of further improving the reciprocating operability and sealing performance during reciprocating motion in low-temperature environments while maintaining the mechanical strength and elongation properties of the functional rubber part of the present invention at room temperature. On the other hand, the upper limit of the ethylene content of the non-oil-extended ethylene butenediene rubber is preferably 59% by mass, more preferably 57% by mass, and particularly preferably 55% by mass, from the viewpoint of further improving the reciprocating operability and sealing performance during reciprocating motion in low-temperature environments while maintaining the mechanical strength and elongation properties of the functional rubber part of the present invention at room temperature.

[0047] The diene content of the non-oil-extended ethylene butene diene rubber is not particularly limited, but from the viewpoint of further reliably improving the reciprocating motion operability and sealing performance of the functional rubber part of the present invention in a low-temperature environment, it is preferably from 2.0% by mass to 13% by mass, more preferably from 2.5% by mass to 10% by mass, and particularly preferably from 3.0% by mass to 8.0% by mass.

[0048] Mooney viscosity (ML) of ethylene butene diene rubber 1+4, 100°C) is not particularly limited, but the lower limit is preferably 15, and particularly preferably 20, from the viewpoint of reliably improving the mechanical strength and elongation properties of the functional rubber part of the present invention under room temperature conditions. 1+4 , 100°C) is preferably 50, particularly preferably 40, from the viewpoint of processability when molding the functional rubber part of the present invention from the rubber composition.

[0049] The amount of non-oil-extended ethylene butene diene rubber is not particularly limited, but the lower limit is preferably 1.0 part by mass, more preferably 5.0 parts by mass, and even more preferably 20 parts by mass, per 100 parts by mass of the rubber component of oil-extended ethylene butene diene rubber, from the viewpoint of improving the mechanical strength of the functional rubber part of the present invention in a room temperature environment while more reliably improving the operability of the functional rubber part of the present invention in a reciprocating motion and the sealing performance during reciprocating motion in a low temperature environment, and 50 parts by mass is particularly preferred from the viewpoint of improving the operability of the functional rubber part of the present invention in a reciprocating motion in a low temperature environment in a balanced manner. On the other hand, the upper limit of the amount of non-oil-extended ethylene butene diene rubber per 100 parts by mass of the rubber component of oil-extended ethylene butene diene rubber is preferably 2500 parts by mass, from the viewpoint of more reliably improving the reciprocating operability and sealing performance during reciprocating motion of the functional rubber part of the present invention in a low-temperature environment; 1000 parts by mass is more preferable, from the viewpoint of further improving the mechanical strength and elongation properties of the functional rubber part of the present invention while reliably improving the reciprocating operability and sealing performance during reciprocating motion of the functional rubber part of the present invention in a low-temperature environment; 500 parts by mass is even more preferable, from the viewpoint of further improving the reciprocating operability of the functional rubber part of the present invention in a low-temperature environment; and 90 parts by mass is particularly preferable, from the viewpoint of balanced improvement in the reciprocating operability and sealing performance during reciprocating motion of the functional rubber part of the present invention in a low-temperature environment.

[0050] <Carbon black> The rubber composition, which is the raw material for the functional rubber part of the present invention, may further contain carbon black in addition to the oil-extended ethylene butene diene rubber, as necessary. By including carbon black, the functional rubber part of the present invention can more reliably obtain mechanical strength at room temperature.

[0051] The amount of carbon black is not particularly limited, but for example, when the non-oil-extended ethylene butenediene rubber is not required, the lower limit is preferably 10 parts by mass per 100 parts by mass of the rubber component of oil-extended ethylene butenediene rubber from the viewpoint of more reliably obtaining the mechanical strength of the functional rubber part of the present invention at room temperature, and 26 parts by mass is particularly preferred from the viewpoint of further improving the mechanical strength and elongation properties of the functional rubber part of the present invention at room temperature. On the other hand, when the non-oil-extended ethylene butenediene rubber is not required, the upper limit of the amount of carbon black is preferably 100 parts by mass, more preferably 70 parts by mass, and particularly preferably 60 parts by mass per 100 parts by mass of the rubber component of oil-extended ethylene butenediene rubber from the viewpoint of reliably improving the reciprocating motion operability and sealing performance of the functional rubber part of the present invention at low temperature.

[0052] Furthermore, when a non-oil-extended ethylene butenediene rubber is further contained, the amount of carbon black is not particularly limited, but the lower limit is preferably 10 parts by mass per 100 parts by mass of the rubber component of the oil-extended ethylene butenediene rubber and the non-oil-extended ethylene butenediene rubber in order to more reliably obtain the mechanical strength of the functional rubber part of the present invention at room temperature, and 26 parts by mass is particularly preferred in order to further improve the mechanical strength and elongation properties of the functional rubber part of the present invention at room temperature. On the other hand, when a non-oil-extended ethylene butenediene rubber is further contained, the upper limit of the amount of carbon black is preferably 80 parts by mass per 100 parts by mass of the rubber component of the oil-extended ethylene butenediene rubber and the non-oil-extended ethylene butenediene rubber in order to reliably improve the reciprocating motion operability and sealing performance during reciprocating motion of the functional rubber part of the present invention at low temperature. The rubber composition that is the raw material for the functional rubber part of the present invention further contains non-oil-extended ethylene butene diene rubber, which allows it to obtain excellent tensile strength in the normal state even when the amount of carbon black blended is reduced. As a result, the functional rubber part of the present invention reliably improves the operability of reciprocating motion and the sealing performance during reciprocating motion in low-temperature environments.

[0053] The arithmetic mean particle size of the carbon black is not particularly limited, but is preferably 20 nm or more and 50 nm or less, and particularly preferably 22 nm or more and 45 nm or less, from the viewpoint of reliably improving the operability and sealing performance during reciprocating motion of the functional rubber part of the present invention in a low-temperature environment while more reliably obtaining mechanical strength in a room-temperature environment.

[0054] <Various additives> The rubber composition, which is the raw material for the functional rubber part of the present invention, may contain various additives as needed, such as processing aids, co-crosslinking agents, and peroxide vulcanizing agents.

[0055] Examples of co-crosslinking agents include ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, triallyl isocyanurate, 1,2-polybutadiene, N,N'-m-phenylene bismaleimide, etc. Examples of peroxide vulcanizing agents include dicumyl peroxide, tert-butyl peroxide, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, 2,5-dimethyl-2,5-di-tert-butylperoxyhexyne-3, tert-butylcumyl peroxide, 1,3-di-tert-butylperoxyisopropylbenzene, 2,5-dimethyl-2,5-dibenzoylperoxyhexane, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxyester, peroxydicarbonate, etc.

[0056] Furthermore, the rubber composition, which is the raw material for the functional rubber part of the present invention, may contain various additives other than the processing aid, co-crosslinking agent, and peroxide vulcanizing agent, such as a crosslinking accelerator, antiaging agent, plasticizer, antioxidant, and flame retardant, as needed.

[0057] Next, a method for preparing the rubber composition, which is the raw material for the functional rubber part of the present invention, will be described. Examples of methods for preparing the rubber composition include mixing and melt-kneading the above-mentioned components using a mixing / kneading means such as a single-screw extruder, twin-screw extruder, kneader, roll mixer, Banbury mixer, tumbler mixer, or Brabender. Furthermore, if necessary, the above-mentioned components may be pre-kneaded before mixing and melt-kneading.

[0058] Next, a method for producing the functional rubber part of the present invention using the above rubber composition as a raw material will be described. The method for producing the functional rubber part of the present invention is not particularly limited, and for example, the rubber composition prepared as described above can be molded into a predetermined shape using a known molding method such as extrusion molding, injection molding, injection compression molding, melt flow molding, inflation molding, compression molding, transfer molding, or cast molding to produce the functional rubber part of the present invention. [Example]

[0059] Next, examples of the present invention will be described, but the present invention is not limited to these examples as long as the spirit of the present invention is not exceeded.

[0060] Examples 1 to 11, Comparative Examples 1 to 6 The components shown in Table 1 below were blended in the blending ratios shown in Table 1 below and kneaded using a kneader for 40 minutes to prepare rubber compositions that are raw materials for functional rubber parts used in Examples 1 to 11 and Comparative Examples 1 to 6. The numbers in Table 1 below indicate parts by mass.

[0061] Details of each component in Table 1 are as follows:

[0062] Non-oil exhibition EBDM K-9330M: Ethylene content 50% by mass, diene content 7.1% by mass, Mooney viscosity (ML 1+4 , 100℃)30, oil extension amount 0 mass%, Mitsui Chemicals, Inc. EPDM EPT-9090M: Non-oil extended ethylene propylene diene rubber, ethylene content 41% by mass, diene content 14% by mass, Mooney viscosity (ML 1+4 , 125℃)58, Mitsui Chemicals, Inc. oil exhibition ebdm K-8370EM: Ethylene content 51% by mass, diene content 4.7% by mass, Mooney viscosity (ML 1+4 , 125℃) 50, oil extension amount 30 mass%, Mitsui Chemicals, Inc.

[0063] carbon black · SEAT G-116 carbon: arithmetic mean particle size 38nm, Tokai Carbon Co., Ltd. · SEAT 6: Arithmetic mean particle size 22nm, Tokai Carbon Co., Ltd.

[0064] polymer oil Lucant LX-004: Ethylene and α-olefin co-oligomer (hydrocarbon polymer oil), Mitsui Chemicals, Inc.

[0065] Peroxide vulcanizing agent · Percumyl D-40: Dicumyl peroxide, NOF Corporation.

[0066] The evaluation items are as follows: (1) Normal tension test (normal tension) Tests were conducted in accordance with JIS K6251, and the tensile strength (mechanical strength) and elongation at room temperature were evaluated using the obtained tensile strength and elongation at break results according to the following criteria. Evaluation criteria for tensile strength at room temperature ×: Less than 10.0 MPa △: 10.0 MPa or more and less than 12.0 MPa 〇: 12.0 MPa or more and less than 16.0 MPa ◎: 16MPa or more Evaluation criteria for elongation at room temperature ×: Less than 200% △: 200% or more but less than 300% ○: 300% or more but less than 400% ◎: 400% or more

[0067] (2) Gehman torsion test Gehman torsion tests were conducted in accordance with JIS K 6261-3. Specifically, test specimens were prepared based on JIS K 6250, and the temperatures T2 (°C) and T10 (°C) corresponding to the torsion angle at 23±2°C and the torsion angles corresponding to moduli 2 and 10 times the torsion angle were measured. Using the T2 (°C) results, the operability in low-temperature environments was evaluated according to the following criteria. Evaluation criteria for operation in low temperature environments ×: Over -45.0℃ 〇: -50.0℃ or more -45.0℃ or less ◎: Less than -50℃

[0068] (3) TR test (low-temperature elastic recovery test) A TR test was conducted in accordance with JIS K 6261-4. Specifically, a test specimen was prepared based on JIS K 6250, and the resulting test specimen was cooled to -70°C while elongated by 50%, and then the temperature was increased to measure the temperature (TR10: unit °C) at which the specimen contracted 10% from the 50% elongation length (i.e., a 10% contraction rate). Using the results of T10 (°C) and TR10 (°C) from the Gehman torsion test, the sealing ability in a low-temperature environment was evaluated according to the following criteria. Note that the lower of the T10 and TR10 evaluation results was used to evaluate the sealing ability in a low-temperature environment. Evaluation criteria for sealing performance in low temperature environments T10 evaluation criteria ×: Over -56.5℃ 〇: -60.0℃ or more -56.5℃ or less ◎: Less than -60.0℃ TR10 evaluation criteria ×: Over -57.0℃ 〇: -60.0℃ or more -57.0℃ or less ◎: Less than -60.0℃

[0069] The measurement results are shown in Table 2 below, and the evaluation results are shown in Table 3 below.

[0070] [Table 1]

[0071] [Table 2]

[0072] [Table 3]

[0073] As shown in Tables 1 to 3, Examples 1 to 11, which are rubber members molded from rubber compositions containing oil-extended ethylene butene diene rubber having an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less, had excellent tensile strength and elongation in the normal state, and also had excellent operability and sealing properties in low-temperature environments. From the above, the rubber members of Examples 1 to 11 had excellent tensile strength and elongation in room-temperature environments, and also had excellent low-temperature properties.

[0074] In particular, in Examples 3 to 11, which are rubber members molded from a rubber composition containing oil-extended ethylene butene diene rubber and non-oil-extended ethylene butene diene rubber, each having an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less, it was found that even when the amount of carbon black compounded was reduced compared to the rubber members of Examples 1 and 2, which did not contain non-oil-extended ethylene butene diene rubber, excellent tensile strength could be obtained in the normal state, and as a result, operability and sealing performance in low-temperature environments were reliably improved.

[0075] Furthermore, a comparison between Examples 3 to 10 and Example 11 shows that the rubber member molded from the rubber composition containing 900 parts by mass or less of non-oil-extended ethylene butene diene rubber per 100 parts by mass of the rubber component of oil-extended ethylene butene diene rubber reliably exhibits improved operability and sealing performance in low-temperature environments, while also exhibiting further improved mechanical strength and elongation properties in room-temperature environments.

[0076] Furthermore, Examples 3 to 10, which are rubber members molded from a rubber composition containing 27 parts by mass or more and 53 parts by mass or less of carbon black per 100 parts by mass of the total of the oil-extended ethylene butenediene rubber rubber component and the non-oil-extended ethylene butenediene rubber, showed further improved mechanical strength and elongation properties at room temperature compared to Example 11, which is a rubber member molded from a rubber composition containing 25 parts by mass of carbon black per 100 parts by mass of the total of the oil-extended ethylene butenediene rubber rubber component and the non-oil-extended ethylene butenediene rubber.

[0077] On the other hand, in Comparative Examples 2 to 6, which are rubber members molded from rubber compositions that do not contain oil-extended ethylene butenediene rubber, it was not possible to achieve both operability in low-temperature environments and sealing performance in low-temperature environments, and low-temperature properties were not obtained.Furthermore, in Comparative Examples 1 and 4, which are rubber members molded from rubber compositions that do not contain oil-extended ethylene butenediene rubber and have a reduced amount of carbon black, it was not possible to obtain mechanical strength in a room-temperature environment. [Industrial Applicability]

[0078] The functional rubber part of the present invention has excellent reciprocating motion operability and sealing properties in low-temperature environments without compromising mechanical strength and elongation properties in room-temperature environments. Therefore, it is highly useful in the field of rubber parts that require reciprocating motion operability and sealing properties during reciprocating motion in extremely low-temperature environments such as -40°C. [Explanation of symbols]

[0079] 1, 2 Umbrella valve 11 Umbrella-shaped part

Claims

1. A functional rubber part molded from a rubber composition containing oil-extended ethylene butene diene rubber having an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less.

2. The functional rubber part according to claim 1, which is used as a check valve, an elastic diaphragm, a bellows, or a sealing member.

3. The functional rubber part according to claim 2, wherein the check valve is an umbrella valve.

4. 3. The functional rubber part according to claim 2, wherein the elastic diaphragm is a diaphragm of a diaphragm pump.

5. 3. The functional rubber part according to claim 2, wherein the sealing member is an O-ring.

6. The functional rubber part according to claim 1, wherein the rubber composition further comprises a non-oil-extended ethylene butene diene rubber.

7. The functional rubber part according to claim 6, wherein the non-oil-extended ethylene butene diene rubber has an ethylene content of 42% by mass or more and 59% by mass or less and a diene content of 2.0% by mass or more and 13% by mass or less.

8. The functional rubber part according to claim 6 or 7, comprising 1.0 part by mass or more and 2500 parts by mass or less of the non-oil-extended ethylene butene diene rubber per 100 parts by mass of the rubber component of the oil-extended ethylene butene diene rubber.

9. The functional rubber part according to claim 1 , wherein the rubber composition further contains carbon black.

10. The functional rubber part according to claim 1, wherein the rubber composition further contains 10 parts by mass or more and 100 parts by mass or less of carbon black per 100 parts by mass of the rubber component of the oil-extended ethylene butene diene rubber.

11. The functional rubber part according to claim 6 or 7, further comprising 10 parts by mass or more and 80 parts by mass or less of carbon black per 100 parts by mass of the rubber component of the oil-extended ethylene butene diene rubber and the non-oil-extended ethylene butene diene rubber combined.

12. The functional rubber part according to claim 9, wherein the carbon black has an arithmetic mean particle size of 20 nm or more and 50 nm or less.

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