Rubber composition and vulcanized product

Abstract

The present invention relates to a rubber composition, which comprises an ethylene-butene-diene terpolymer, a CTAB with a specific surface area of ​​30 m 2 / g and above and 150m 2 / g or less of silica, a silane coupling agent and a crosslinking agent, wherein the content of the silica is greater than 25 parts by weight and less than 90 parts by weight relative to 100 parts by weight of the ethylene-butene-diene terpolymer.

Description

Technical Field

[0001] The present invention relates to a rubber composition and a vulcanized molded product using the rubber composition. Background Art

[0002] In the past, rubber materials such as nitrile rubber (NBR), fluororubber (FKM), and acrylic rubber (ACM) have been widely used as materials for various rubber molded products (such as sealing parts, electrical insulators, vibration-proof rubber, sound-proof rubber, general industrial rubber, etc.) due to their properties. However, these materials have the problem of not being able to fully exert their rubber properties in low-temperature environments (such as below -40°C), and there is an urgent need to use rubber materials with excellent cold resistance.

[0003] As such a rubber material, ethylene-propylene-diene terpolymer (hereinafter also referred to as "EPDM") is widely known. EPDM has better cold resistance than the above rubber materials and can fully exert rubber properties even in low temperature environments, so it can be effectively used as a rubber material for cold-resistant sealing parts. On the other hand, in recent years, there is sometimes a need for sealing parts to have better cold resistance, and there is a problem that even EPDM cannot fully exert rubber properties.

[0004] As a rubber material to replace EPDM, ethylene-butene-diene terpolymer (EBDM) has attracted much attention. Patent Document 1 discloses the following: a sealing component for high-pressure hydrogen equipment manufactured using a rubber composition has excellent low-temperature sealing and blistering resistance, and the rubber composition contains ethylene-butene-ethylidene norbornene terpolymer (EBENB) as an ethylene-butene-diene terpolymer and fillers such as carbon black, silicic acid, and silicates. Patent Document 2 discloses the following: by using a rubber composition containing EBENB, carbon black, a hardness modifier, and a crosslinking agent, a rubber molded product having the same level of hardness as a rubber product using conventional EPDM and excellent low-temperature sealing can be obtained.

[0005] On the other hand, recent sealing products are required to have not only high sealing properties in low temperature environments but also electrical insulation properties from the viewpoint of corrosion prevention. In addition, since the copolymer of EBENB has very high adhesion and adheres to the surface of a kneading machine, especially an open roll kneading machine, it is expected to improve the productivity (kneading processability) of the rubber composition in the kneading process.

[0006] Patent Documents 1 and 2 teach that, for example, a rubber composition containing EBENB and carbon black can be used to impart excellent low-temperature sealing properties to a rubber molded product (sealing component), but do not mention electrical insulation and kneading processability. Therefore, it is desirable to develop a rubber composition that can impart both low-temperature sealing properties and electrical insulation properties to a sealing component and has excellent kneading processability. In addition, since a sealing product may be partially permanently deformed (deformed) during long-term use, thereby reducing the sealing performance, it is also desirable to have good compression set characteristics when the rubber composition is used for sealing purposes.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: International Publication No. 2017-170189

[0010] Patent Document 2: International Publication No. 2017-170190 Summary of the invention

[0011] Problems to be solved by the invention

[0012] The present invention provides a rubber composition which has excellent kneading processability and is suitable for producing a vulcanized molded product having good compression set characteristics and excellent low-temperature characteristics and electrical insulation properties.

[0013] Technical means to solve problems

[0014] The rubber composition according to the embodiment of the present invention comprises an ethylene-butene-diene terpolymer, a CTAB having a specific surface area of ​​30 m 2 / g and above and 150m 2 / g or less of silica, a silane coupling agent, and a crosslinking agent, wherein the content of the silica is 25 parts by weight or more and 90 parts by weight or less based on 100 parts by weight of the ethylene-butene-diene terpolymer.

[0015] In one embodiment of the present invention, the ethylene-butene-diene terpolymer is an ethylene-butene-ethylidene norbornene terpolymer.

[0016] In one embodiment of the present invention, the iodine value of the ethylene-butene-diene terpolymer is 3 or more and 20 or less.

[0017] In one embodiment of the present invention, the content of the silane coupling agent is 0.5 parts by weight or more and 3.0 parts by weight or less based on 100 parts by weight of the ethylene-butene-diene terpolymer.

[0018] In one embodiment of the present invention, the cross-linking agent is an organic peroxide.

[0019] The vulcanized molded product according to the embodiment of the present invention is obtained by vulcanizing and molding the above-mentioned rubber composition.

[0020] In one embodiment of the vulcanized molded article of the present invention, the value of TR-70 measured in accordance with JIS K6261:2006 is -40°C or less.

[0021] In one embodiment of the vulcanized molded article of the present invention, the volume resistivity measured in accordance with JIS K6271-1:2015 is 1×10 12 Ω·cm or more.

[0022] In one embodiment of the vulcanized molded article of the present invention, the compression set rate measured under the conditions of 130° C. and 70 hours in accordance with JIS K6262:2013 is 20% or less.

[0023] In one embodiment of the present invention, the vulcanized molded product is a sealing component.

[0024] Effects of the Invention

[0025] According to the present invention, there can be provided a rubber composition which is excellent in kneading processability and is suitable for producing a vulcanized molded product having good compression set characteristics and excellent low-temperature characteristics and electrical insulation properties. DETAILED DESCRIPTION

[0026] The following is an explanation of the embodiment of the present invention. The rubber composition involved in this embodiment contains ethylene-butene-diene terpolymer (hereinafter also referred to as "EBDM") as a rubber component, silica as a filler, a silane coupling agent and a crosslinking agent. The silica used has a 30 m 2 / g and above and 150m 2 / g or less CTAB specific surface area, and, in the rubber composition, relative to 100 weight parts of ethylene-butene-diene terpolymer, the content of silicon dioxide is more than 25 weight parts and less than 90 weight parts. In the rubber composition containing EBDM that the present embodiment relates to, by coordinating silicon dioxide with a specified CTAB specific surface area within a specified content range, a rubber composition of a vulcanized molded product having excellent mixing processability and being suitable for manufacturing low-temperature characteristics and electrical insulation properties can be obtained. In addition, by adding a silane coupling agent, the obtained vulcanized molded product can be given good compression set characteristics. And then, because the vulcanized molded product shows excellent low-temperature characteristics, the sealing component as an example of the use form of this vulcanized molded product can play an excellent sealing performance under low temperature environment. Below, each component constituting the rubber composition that the present embodiment relates to is described in detail.

[0027] <Rubber ingredients>

[0028] In the present embodiment, the rubber composition contains EBDM as the main component (rubber component) for vulcanized molded products. As ethylene-butene-diene terpolymer, for example, ethylene-butene-ethylidene norbornene terpolymer (hereinafter also referred to as "EBENB") is preferred. The characteristics of rubber materials such as EBENB and EPDM have a great impact on the overall material cost and production efficiency of the rubber composition (or vulcanized molded product). In addition, since the softness of EBDM is better than EPDM, it is excellent in cold resistance (low temperature characteristics), and the processability such as kneading property, dispersibility, and moldability are excellent, and the production efficiency is greatly improved, so the cost reduction of the production process can be achieved. In this way, the rubber composition involved in the present embodiment using EBDM, especially EBENB, is excellent in low temperature characteristics compared with the previous rubber composition using EPDM. In addition, from the viewpoint of material cost and production efficiency, the production cost of vulcanized molded products can be reduced.

[0029] As EBDM, any EBDM obtained by copolymerizing various diene components in ethylene and butene can be used. When EBENB is used as EBDM, EBENB is not particularly limited as long as it is a copolymer obtained by copolymerizing ethylidene norbornene in ethylene and butene. As EBDM, a copolymer prepared by synthesizing various monomer components can be used, or various commercially available products such as "EBT K-9330M" manufactured by Mitsui Chemicals can be used directly.

[0030] The iodine value (g / 100g) of EBDM is preferably 3 or more and 20 or less, more preferably 5 or more and 18 or less. By making the iodine value range from 3 or more to 20 or less, excellent heat aging resistance and weather resistance can be given to the vulcanized product, and degradation of the vulcanized product can be prevented. In addition, even in a low temperature environment, the molecular state of EBDM can be maintained stably, and the low temperature characteristics can be improved.

[0031] Compared with EPDM, EBDM has a Mooney viscosity of ML 1+4 The polymer viscosity expressed at (100°C) is low and is also excellent in processability (such as kneading and molding properties). Therefore, by using EBDM instead of EPDM, productivity such as molding efficiency is improved and production costs can be reduced. The Mooney viscosity ML of this EBDM 1+4 (100°C) is preferably 10 or more and 45 or less, more preferably 15 or more and 35 or less. 1+4 (100°C) is 10 or more, which can prevent the compression set of the vulcanized product from becoming too large and provide appropriate tensile strength. 1+4(100°C) is 45 or less, which can prevent the processability of the rubber composition from being reduced. 1+4 (100° C.) can be measured in accordance with the provisions of JIS K6300-1:2013.

[0032] The content of the ethylene component in EBDM is preferably 60 mol % or more and 80 mol % or less, more preferably 65 mol % or more and 75 mol % or less. By making the content of the ethylene component be the scope of 60 mol % or more and 80 mol % or less, the glass transition temperature Tg of EBDM is shown as a minimum value, and cold resistance is improved.

[0033] In the rubber composition, the EBDM constituting the rubber component may be used alone or in combination of two or more. In addition, as other rubber components, ethylene-propylene-diene terpolymer (EPDM) and the like may be used in combination.

[0034] <Filling Agent>

[0035] In this embodiment, the rubber composition contains CTAB (cetyltrimethylammonium bromide) with a specific surface area of ​​30 m 2 / g and above and 150m 2 / g or less of silica. By including silica in the rubber composition as a filler, the mechanical strength and compression set of the resulting vulcanized molded product can be improved while maintaining the original electrical insulation of the polymer. In addition, by making the CTAB specific surface area of ​​silica 30m 2 / g and above and 150m 2 / g or less, thereby preventing the rubber composition from adhering to the mixing mill, especially the roller surface of the roller mixing mill, during the mixing process of the rubber composition, thereby improving the mixing processability. As a result, the workability of the mixing process can be improved and the productivity can be increased. Furthermore, by using CTAB with a specific surface area of ​​150 m 2 / g or less of silica, thereby optimizing the dispersibility of silica and improving the compression set characteristics. 2 / g and above and 150m 2 / g or less of silica can provide a rubber composition that has excellent kneading processability and can produce vulcanized molded products with excellent electrical insulation and improved compression set characteristics. The CTAB specific surface area of ​​silica is particularly preferably 30 m 2 / g or more and 100m 2 The range of CTAB specific surface area is not more than 100 / g, and by using silica having a CTAB specific surface area in such a range, the compression set characteristics can be further improved.

[0036] As commercially available silica, for example, "Nipsil E74P" (CTAB specific surface area: 33 m 2 / g), "Carplex (registered trademark) #101" manufactured by Evonik (CTAB specific surface area: 50 m 2 / g), "Ultrasil (registered trademark) 360" manufactured by Evonik (CTAB specific surface area: 55 m 2 / g), "Carplex (registered trademark) #1120" manufactured by Evonik (CTAB specific surface area: 85 m 2 / g), "Nipsil ER" manufactured by Tosoh Silica Co., Ltd. (CTAB specific surface area: 115 m 2 / g), and "Carplex (registered trademark) #67" manufactured by Evonik (CTAB specific surface area: 140 m 2 / g) etc. Silica may be used alone or in combination of two or more.

[0037] For the content of silicon dioxide contained in rubber combination, be preferably more than 30 weight parts and below 90 weight parts relative to EBDM 100 weight parts, more preferably more than 30 weight parts and below 70 weight parts.By making this content be more than 30 weight parts and below 90 weight parts, thereby rubber combination demonstrates excellent mixing processability, and can give the low temperature characteristics of vulcanized molded product excellence.Like this, by making the content of silicon dioxide be more than 30 weight parts and below 90 weight parts relative to EBDM 100 weight parts, can provide the rubber combination of excellent mixing processability and can manufacture the vulcanized molded product of low temperature characteristics excellence.The content of silicon dioxide is preferably more than 30 weight parts and below 70 weight parts particularly, by strictly controlling the content of silicon dioxide according to required hardness, can further improve compression set characteristics.

[0038] In the rubber composition, fillers other than silica can be further mixed. In the case of using other fillers other than silica in combination, if the content of silica is within the above range, the type and amount of other fillers can be arbitrarily determined according to its purpose. As such other fillers, carbon black, calcium carbonate, clay, talc, etc., which are usually used as reinforcing materials added to the rubber composition, can be appropriately added to obtain the desired physical properties. It should be noted that, in the case of combining fillers such as carbon black that show conductivity for coloring, it can be appropriately adjusted within the range where the vulcanized molded product shows the desired electrical insulation.

[0039] <Silane coupling agent>

[0040] The rubber composition involved in the present embodiment also contains a silane coupling agent. As the silane coupling agent, for example: vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tri (2-methoxyethoxy) silane and other vinyl-containing alkoxy silane; γ-aminopropyl triethoxysilane, γ-aminopropyl trimethoxysilane, N-β-aminoethyl-γ-aminopropyl trimethoxysilane, N-β-aminoethyl-γ-aminopropyl triethoxysilane and other amino-containing alkoxy silanes, etc. Silane coupling agents can be used alone or in combination of two or more. The amount of silane coupling agent is not particularly limited, and is 0.5 parts by weight or more and 3.0 parts by weight or less relative to 100 parts by weight of EBDM, preferably 0.5 parts by weight or more and 1.5 parts by weight or less. By adding a proper amount of silane coupling agent, the adhesion between rubber and silica can be improved, and the compression set characteristics as a vulcanized molded product can be improved.

[0041] <Crosslinking agent>

[0042] The rubber composition also contains a cross-linking agent for forming a cross-linked EBDM. As a cross-linking agent, an organic peroxide is mainly preferred. As an organic peroxide, for example, dialkyl peroxides, peroxyketals, diacyl peroxides, peroxyesters, etc. can be cited. Specifically, di-tert-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(tert-butyl peroxy)hexane, 2,5-dimethyl-2,5-di(tert-butyl peroxy)-3-hexyne, tert-butyl cumyl peroxide, 1,3-di(tert-butyl peroxyisopropyl)benzene, 2,5-dimethyl-2,5-di(benzoyl peroxy)hexane, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, 4,4-di(tert-butyl peroxy) valeric acid n-butyl ester, etc. The cross-linking agent can be used alone or in combination of two or more.

[0043] The amount of the crosslinking agent is preferably 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight, relative to 100 parts by weight of EBDM. By making the amount of the crosslinking agent in the range of 0.5 to 10 parts by weight, it is possible to prevent the rubber composition from foaming during EBDM vulcanization and preventing vulcanization molding, and because the crosslinking density is good, it is easy to manufacture a vulcanized molded product showing sufficient physical properties.

[0044] Such a crosslinking agent may be a commercially available product as it is, or a masterbatch containing the above-mentioned organic peroxide may be used. A masterbatch is preferred because it can improve kneading properties and dispersibility when preparing a rubber composition.

[0045] <Other additives>

[0046] The rubber composition involved in the present embodiment can also contain a crosslinking accelerator as needed. As a crosslinking accelerator, triallyl isocyanurate (TAC), triallyl cyanate (TAC), liquid polybutadiene, N,N'-m-phenylene bismaleimide, trimethylol trimethacrylate, etc. can be used. One type of crosslinking accelerator can be used alone, or two or more types can be used in combination. The amount of the crosslinking accelerator is not particularly limited, and is preferably more than 0.5 weight parts and less than 3.0 weight parts relative to 100 weight parts of EBDM. By adding a suitable amount of a crosslinking accelerator, the crosslinking efficiency is improved, and the heat resistance and mechanical properties are improved, so the stability as a vulcanized molded product can also be improved.

[0047] The rubber composition involved in the present embodiment may further contain a plasticizer as needed. As the plasticizer, process oils with aliphatic hydrocarbons as the main component can be cited, for example: "Diana Process Oil PW-380" manufactured by Idemitsu Kosan Co., Ltd., "Diana Process Oil PW-220" manufactured by Idemitsu Kosan Co., Ltd., etc. The plasticizer can be used alone or in combination of two or more. In particular, compared with paraffin wax having a similar chemical structure, process oil is a low molecular weight, so process oil is more preferred in terms of exerting a unique effect that cannot be achieved when paraffin wax is added. The amount of plasticizer added is not particularly limited, and is preferably more than 1.0 weight part and less than 30 weight parts relative to 100 weight parts of EBDM.

[0048] The rubber composition involved in this embodiment may further contain a lubricant as needed. As a lubricant, a lubricant having a melting point near the surface temperature of the mixer, i.e., 50°C to 100°C, is preferably a fatty acid lubricant. As a fatty acid lubricant, for example, fatty acid amide, fatty acid zinc, fatty acid ester, etc. can be cited. As fatty acid amide, saturated fatty acid amide and unsaturated fatty acid amide can be cited, and according to the structure, it can be a monoamide, a substituted amide, a bisamide, and a hydroxymethylamide. As fatty acid zinc, saturated fatty acid zinc, unsaturated fatty acid zinc, their derivatives, and mixtures thereof can be cited. As fatty acid esters, esters of lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, etc. can be cited. In addition to fatty acid lubricants, non-zinc lubricants and silicone lubricants can also be used. The amount of lubricant is not particularly limited, and is preferably 0.5 parts by weight or more and 3.0 parts by weight or less relative to 100 parts by weight of EBDM. By adding a proper amount of lubricant, the mixing processability is improved, and oil leakage can also be prevented.

[0049] In addition to the above components, rubber compounding agents commonly used in the rubber industry such as acid absorbents and antioxidants may be appropriately added to the rubber composition as needed. The total amount of the rubber compounding agents is preferably 300 parts by weight or less per 100 parts by weight of EBDM.

[0050] <Method for producing rubber composition>

[0051] The method for producing the rubber composition according to the present embodiment is not particularly limited, and the rubber composition can be produced by appropriately mixing the above-described EBDM, silica, silane coupling agent, and crosslinking agent, and any various additives as required, in a predetermined ratio, and then kneading them using a kneading machine such as a single-screw extruder, a twin-screw extruder, a roll, a Banbury mixer, a kneader, or a high-shear mixer. It should be noted that pre-mixing can be performed as required before kneading.

[0052] <Vulcanized products>

[0053] The vulcanized molded product can be manufactured by vulcanization molding of the rubber composition involved in the present embodiment. Using an injection molding machine, a compression molding machine, etc., the rubber composition is vulcanized by pressurization for about 0.5 minutes to 30 minutes at about 150°C to 230°C. In addition, after implementing such a primary vulcanization (pressurization vulcanization), in order to reliably vulcanize the inside of the vulcanized molded product, a secondary vulcanization can be performed as needed. The secondary vulcanization can usually be performed by baking and heating at about 150°C to 250°C for about 0.5 hours to 24 hours.

[0054] The vulcanized molded product obtained by vulcanizing the rubber composition according to the present embodiment shows excellent low temperature properties even at -40°C or below, and is particularly suitable for use in a low temperature environment (e.g., -40°C to -60°C). As the low temperature properties of such a vulcanized molded product, for example, the value of TR-70 measured in accordance with JIS K6261:2006 is preferably -40°C or below.

[0055] In addition, the vulcanized molded product obtained by vulcanizing the rubber composition according to the present embodiment exhibits excellent electrical insulation. As the electrical insulation of such a vulcanized molded product, for example, the volume resistivity measured in accordance with JIS K6271-1:2015 is preferably 1×10 12 Ω·cm or more.

[0056] In addition, it is preferred that the compression set characteristics of the vulcanized product obtained by vulcanizing the rubber composition involved in the present embodiment are good. As the compression set characteristics of such a vulcanized product, for example, the compression set rate measured under the conditions of 130° C. and 70 hours according to JIS K6262: 2013 is preferably 20% or less, and more preferably 15% or less.

[0057] The vulcanized molded product of this embodiment shows good compression set characteristics, and has excellent low temperature characteristics and electrical insulation, and is therefore suitable for use as, for example, a sealing component or an insulator. In particular, when the vulcanized molded product is a sealing component, such a sealing component exhibits excellent sealing performance in a low temperature environment. Among them, as a sealing component requiring sealing and electrical insulation in a low temperature environment, it is suitable for use as a sealing gasket for electric vehicles (e-Mobility).

[0058] The shape of the vulcanized product is not particularly limited, and can be made into various shapes according to the purpose. For example, when the vulcanized product is used as a sealing component, the shape of the sealing component can include an O-ring, a gasket, a packing, a sheet, etc. In addition, the use of the vulcanized product is not limited to the above-mentioned sealing components, and it is also suitable as other industrial sealing components such as insulating seals and cold-use seals.

[0059] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, but includes all aspects included in the concept of the present invention and the claims, and various modifications can be made within the scope of the present invention.

[0060] Example

[0061] Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples unless the scope of the present invention is exceeded.

[0062] (Example 1)

[0063] 100 parts by weight of EBDM (iodine value: 16 (g / 100g), trade name "EBT K-9330M", manufactured by Mitsui Chemicals), 30 parts by weight of silica A (trade name "Nipsil E74P", manufactured by Tosoh Silica Co., Ltd.), 1 part by weight of a silane coupling agent (trade name "A171", manufactured by Momentive), 3 parts by weight of a crosslinking agent (trade name "ParkMill D", manufactured by NOF Corporation) and 1 part by weight of a lubricant (trade name "Diamid0-200T", manufactured by Nippon Chemical Co., Ltd.) were kneaded by an open roll mixer to prepare a rubber composition.

[0064] <Mixed Processability>

[0065] The obtained rubber composition was evaluated for kneading processability based on its adhesion to the kneading machine surface. If it could be stably kneaded, it was evaluated as "○", and if the rubber composition was severely adhered to the kneading machine surface and could not be continuously kneaded, it was evaluated as "×". The results are shown in Table 1.

[0066] <Low temperature characteristics>

[0067] For the obtained rubber composition, a sheet mold was used to perform press vulcanization (primary vulcanization) at 180°C for 10 minutes and open vulcanization (secondary vulcanization) at 150°C for 24 hours, and a sheet-shaped vulcanized product with a thickness of 2 mm was prepared as a test piece. For the test piece of the obtained vulcanized product, the temperature of TR-70 was measured according to JIS K6261:2006. TR-70 is the temperature at which the shrinkage rate reaches 70% when the elastic modulus is restored after the test piece is stretched 50% and frozen and then heated up. The lower the temperature measured by TR-70, the better the rubber elasticity has been restored at low temperature and the lower the low temperature characteristics. In a sealing component that is given sealing properties by rubber elasticity, the lower the temperature, the better. It can be seen that this material property shows a preferred sealing performance from the perspective of rubber elasticity. If TR-70 is below -40°C, it is evaluated as "○", and if TR-70 exceeds -40°C, it is evaluated as "×". The results are shown in Table 1.

[0068] <Electrical insulation>

[0069] For the test piece of the obtained vulcanized molded product, 500V was applied between the electrodes and the volume resistivity was measured after 1 minute according to JIS K6271-1:2015. The higher the volume resistivity, the better the electrical insulation. If the volume resistivity is 1×10 12 Ω·cm or more, it is rated as "○", and if the volume resistivity is less than 1×10 12 The results are shown in Table 1.

[0070] <Compression set characteristics>

[0071] The test piece of the vulcanized molded product obtained by stacking 3 sheets was measured for the compression set rate after 70 hours at 130°C in air according to JIS K6262:2013. The lower the compression set rate, the better the compression set characteristics. If the compression set rate is less than 15%, it is evaluated as "○", if the compression set rate is less than 20%, it is evaluated as "△", and if the compression set rate exceeds 20%, it is evaluated as "×". "△" or above is evaluated as reaching the qualified level. The results are shown in Table 1.

[0072] (Example 2)

[0073] A rubber composition and a vulcanized molded product thereof were prepared in the same manner as in Example 1 except that the blending amount of silica A was changed to 60 parts by weight, and the above-mentioned measurements and evaluations were performed.

[0074] (Example 3)

[0075] A rubber composition and a vulcanized product thereof were prepared in the same manner as in Example 1 except that the blending amount of silica A was changed to 90 parts by weight, and the above-mentioned measurements and evaluations were performed.

[0076] (Example 4)

[0077] A rubber composition and a vulcanized molded product thereof were prepared in the same manner as in Example 1, except that silica B (trade name: "Carplex (registered trademark) #101", manufactured by Evonik) was used instead of silica A, and the above-mentioned measurements and evaluations were performed.

[0078] (Example 5)

[0079] A rubber composition and a vulcanized molded product thereof were prepared in the same manner as in Example 1, except that silica C (trade name: "Ultrasil (registered trademark) 360", manufactured by Evonik) was used instead of silica A, and the above-mentioned measurements and evaluations were performed.

[0080] (Example 6)

[0081] A rubber composition and a vulcanized molded product thereof were prepared in the same manner as in Example 1, except that silica D (trade name: "Carplex (registered trademark) #1120", manufactured by Evonik) was used instead of silica A, and the above-mentioned measurements and evaluations were performed.

[0082] (Example 7)

[0083] A rubber composition and a vulcanized product thereof were prepared in the same manner as in Example 1 except that silica E (trade name: "Nipsil ER", manufactured by Tosoh Silica Co., Ltd.) was used instead of silica A, and the above-mentioned measurements and evaluations were performed. The results are shown in Table 1.

[0084] (Example 8)

[0085] A rubber composition and a vulcanized molded product thereof were prepared in the same manner as in Example 1, except that silica F (trade name: "Carplex (registered trademark) #67", manufactured by Evonik) was used instead of silica A, and the above-mentioned measurements and evaluations were performed. The results are shown in Table 1.

[0086] (Comparative Example 1)

[0087] A rubber composition and a vulcanized molded product thereof were prepared in the same manner as in Example 1 except that the blending amount of silica A was changed to 20 parts by weight, and the above-mentioned measurements and evaluations were performed.

[0088] (Comparative Example 2)

[0089] A rubber composition and a vulcanized molded product thereof were prepared in the same manner as in Example 1 except that the blending amount of silica A was changed to 100 parts by weight, and the above-mentioned measurements and evaluations were performed.

[0090] (Comparative Example 3)

[0091] A rubber composition and a vulcanized product thereof were prepared in the same manner as in Example 1 except that 30 parts by weight of silica G (trade name: "Nippil LP", manufactured by Tosoh Silica Co., Ltd.) was added instead of silica A, and the above-mentioned measurements and evaluations were performed.

[0092] (Comparative Example 4)

[0093] A rubber composition and a vulcanized product thereof were prepared in the same manner as in Example 1 except that 20 parts by weight of silica H (trade name: "Ultrasil (registered trademark) 9500GR", manufactured by Evonik) was added instead of silica A, and the above-mentioned measurements and evaluations were performed. The results are shown in Table 1.

[0094] (Comparative Example 5)

[0095] A rubber composition and a vulcanized molded product thereof were prepared in the same manner as in Example 1, and the above-mentioned measurements and evaluations were performed, except that 80 parts by weight of carbon black (ISAF: Intermediate Super Abrasion Furnace) carbon black: trade name "Show Black N220", manufactured by Cabot Japan) was added instead of silica A and no silane coupling agent was included. The results are shown in Table 1.

[0096] (Comparative Example 6)

[0097] A rubber composition and a vulcanized molded product thereof were prepared in the same manner as in Example 1 except that the silane coupling agent was not contained, and the above-mentioned measurements and evaluations were performed. The results are shown in Table 1.

[0098] (Comparative Example 7)

[0099] A rubber composition and a vulcanized product thereof were prepared in the same manner as in Example 1 except that EPDM (trade name: "EP33", manufactured by JSR Corporation) was added instead of EBDM, and the above-mentioned measurements and evaluations were performed.

[0100]

[0101] The components shown in Table 1 above are as follows.

[0102] EBDM: Ethylene-butene-diene terpolymer (iodine value: 16 (g / 100g), trade name "EBT K-9330M", manufactured by Mitsui Chemicals, Inc.)

[0103] EPDM: Ethylene-propylene-diene terpolymer (trade name "EP33", manufactured by JSR Corporation)

[0104] Silica A: trade name "Nipsil E74P", manufactured by Tosoh Silica Co., Ltd. (CTAB specific surface area: 33 m 2 / g)

[0105] Silica B: trade name "Carplex (registered trademark) #101", manufactured by Evonik (CTAB specific surface area: 50 m 2 / g)

[0106] Silica C: trade name "Ultrasil (registered trademark) 360", manufactured by Evonik (CTAB specific surface area: 55 m 2 / g)

[0107] Silica D: trade name "Carplex (registered trademark) #1120", manufactured by Evonik (CTAB specific surface area: 85 m 2 / g)

[0108] Silica E: trade name "Nipsil ER", manufactured by Tosoh Silica Co., Ltd. (CTAB specific surface area: 115 m 2 / g)

[0109] Silica F: trade name "Carplex (registered trademark) #67", manufactured by Evonik (CTAB specific surface area: 140 m2 / g)

[0110] Silica G: trade name "Nipsil LP", manufactured by Tosoh Silica Co., Ltd. (CTAB specific surface area: 154 m 2 / g)

[0111] Silica H: trade name "Ultrasil (registered trademark) 9500GR", manufactured by Evonik (CTAB specific surface area: 220 m 2 / g)

[0112] Silane coupling agent: Trade name "A171", manufactured by Momentive

[0113] · Cross-linking agent: Trade name "Park Mill D", manufactured by Nippon Oil & Fats Co., Ltd.

[0114] Lubricant: Trade name "Diamid 0-200T", manufactured by Nippon Chemical Industry Co., Ltd.

[0115] Carbon black: Intermediate Super Abrasion Furnace (ISAF) carbon black (trade name "Show Black N220", manufactured by Cabot Japan)

[0116] In addition, the values ​​of the above-mentioned components in the above-mentioned Table 1 represent "parts by weight".

[0117] As shown in Table 1, in Examples 1 to 8 (the rubber composition containing EBDM is blended with CTAB in an amount of 25 parts by weight or more and 90 parts by weight or less relative to 100 parts by weight of EBDM) with a specific surface area of ​​30 m 2 / g and above and 150m 2 / g or less of silica and a silane coupling agent (in the case of the rubber compositions of Examples 1 to 8), the rubber compositions did not adhere to the surface of the mixer and could be stably mixed, with excellent mixing processability. In addition, in the vulcanized molded articles made using the rubber compositions of Examples 1 to 8, TR-70 was below -40°C and the volume resistivity was 1×10 12 Furthermore, in the vulcanized products made using the rubber compositions of Examples 1 to 8, the compression set ratio was 20% or less, and thus good compression set characteristics were exhibited, and in particular, Examples 1 to 2 and 4 to 6 exhibited excellent compression set characteristics.

[0118] On the other hand, in Comparative Example 1 (CTAB specific surface area is 30 m2 relative to 100 parts by weight of EBDM), 2 / g and above and 150m 2 / g or less and the content of silica is less than 30 parts by weight), the rubber composition adheres to the surface of the mixer and cannot be continuously kneaded, resulting in poor kneading processability.

[0119] In Comparative Example 2 (relative to 100 parts by weight of EBDM, the specific surface area of ​​CTAB is 30 m 2 / g and above and 150m 2 / g or less and the content of silica exceeds 90 parts by weight), the TR-70 of a vulcanized molded product produced using the rubber composition exceeds -40°C, and the low-temperature characteristics are poor.

[0120] In Comparative Examples 3 and 4 (CTAB with a specific surface area of ​​more than 150 m 2 / g of silica), the rubber composition adhered to the surface of the mixer, and continuous mixing could not be performed, resulting in poor mixing processability. In addition, the compression set rate exceeded 20%, and the compression set characteristics were also poor.

[0121] In Comparative Example 5 (using carbon black instead of CTAB with a specific surface area of ​​30 m 2 / g and above and 150m 2 / g or less of silica), a vulcanized molded article made using the rubber composition exhibits a TR-70 exceeding -40°C and a volume resistivity of less than 1×10 12 Ω·cm, thus failing to impart excellent low temperature properties and electrical insulation to the vulcanized molded product. In addition, since no silane coupling agent was used, the compression set rate exceeded 20%, and the compression set properties were also poor.

[0122] In Comparative Example 6 (no silane coupling agent was used), the vulcanized molded article produced using the rubber composition showed a compression set ratio exceeding 20%, and good compression set characteristics could not be imparted to the vulcanized molded article.

[0123] In Comparative Example 7 (using EPDM instead of EBDM as the rubber component), the vulcanized molded product produced using the rubber composition showed a TR-70 exceeding -40°C, and excellent low-temperature properties could not be imparted to the vulcanized molded product.

[0124] From the above results, it can be seen that by mixing the rubber composition containing EBDM in an amount of 25 parts by weight or more and 90 parts by weight or less relative to 100 parts by weight of EBDM, the specific surface area of ​​30 m 2 / g and above and 150m 2 / g or less of silica can provide a rubber composition that has excellent kneading processability and is suitable for manufacturing vulcanized molded products that have good compression set characteristics and excellent low-temperature characteristics and electrical insulation. Therefore, for example, when the vulcanized molded product is a sealing component, such a sealing component can exhibit excellent sealing performance in a low-temperature environment and is particularly suitable for use as a sealing gasket for e-Mobility.

Claims

1. A rubber composition comprising an ethylene-butene-diene terpolymer, a CTAB having a specific surface area of ​​30 m 2 / g and above and 150m 2 / g or less of silica, silane coupling agent and crosslinking agent, The content of the silicon dioxide is 25 parts by weight or more and 90 parts by weight or less relative to 100 parts by weight of the ethylene-butene-diene terpolymer, The content of ethylene component in the ethylene-butene-diene terpolymer is 60 mol% or more and 80 mol% or less, The ethylene-butene-diene terpolymer is an ethylene-butene-ethylidene norbornene terpolymer, The vulcanized molded article obtained by press-vulcanizing the rubber composition at 150° C. to 230° C. for 0.5 to 30 minutes and then baking and heating at 150° C. to 250° C. for 0.5 to 24 hours has a TR-70 value of -40° C. or less as measured in accordance with JIS K6261:2006.

2. The rubber composition according to claim 1, wherein The ethylene-butene-diene terpolymer has an iodine value of 3 or more and 20 or less.

3. The rubber composition according to claim 1 or 2, wherein: The content of the silane coupling agent is 0.5 parts by weight or more and 3.0 parts by weight or less relative to 100 parts by weight of the ethylene-butene-diene terpolymer.

4. The rubber composition according to claim 1 or 2, wherein The cross-linking agent is an organic peroxide. 5 . A vulcanized molded article obtained by vulcanizing the rubber composition according to claim 1 , wherein the value of TR-70 measured in accordance with JIS K6261:2006 is −40° C. or less.

6. The vulcanized molded article according to claim 5, wherein The volume resistivity measured according to JIS K6271-1:2015 is 1×10 12 Ω·cm or more.

7. The vulcanized molded article according to claim 5, wherein The compression set rate measured under the conditions of 130° C. and 70 hours in accordance with JIS K6262:2013 is 20% or less.

8. The vulcanized molded article according to claim 5, wherein The vulcanized molded product is a sealing component.

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