Composition and fuel cell gasket

Abstract

To provide a composition comprising an ethylene / α-olefin / non-conjugated polyene copolymer and an organic peroxide, which can form a molded product having excellent cold resistance in spite of a small content of the organic peroxide.SOLUTION: There is provided a composition comprising a specific ethylene / α-olefin / non-conjugated polyene copolymer (A), carbon black (B) and an organic peroxide (C), wherein the content of the carbon back (B) is 5 to 150 pts.mass and the content of the organic peroxide (C) is 0.01 pt.mass or more and 2.0 pts.mass based on 100 pts.mass of the copolymer (A).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composition and a fuel cell gasket.

Background Art

[0002] Ethylene-α-olefin-non-conjugated polyene copolymers such as ethylene-propylene-diene copolymer (EPDM) usually do not have unsaturated bonds in the main chain of their molecular structure. Therefore, compared with general-purpose conjugated diene rubbers, the above copolymers are excellent in, for example, weather resistance. The above copolymers are widely used in applications such as automotive parts, industrial machinery parts, wire materials, electronic and electrical parts, building and civil engineering materials, and industrial material parts (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to improve the physical properties of a molded body obtained from a composition containing an ethylene-α-olefin-non-conjugated polyene copolymer, an organic peroxide may be blended as a crosslinking agent and a crosslinking treatment may be performed. In order to form a molded body having desired physical properties, it may be considered to increase the content of the organic peroxide. However, the price of organic peroxides is generally high. Therefore, a composition having a high content of organic peroxide is costly. On the other hand, a composition containing an ethylene-α-olefin-non-conjugated polyene copolymer and having a low content of organic peroxide tends to have difficulty in forming a molded body excellent in cold resistance.

[0005] An object of the present invention is to provide a composition containing an ethylene·α-olefin·non-conjugated polyene copolymer and an organic peroxide, which can form a molded article having excellent cold resistance despite a low content of the organic peroxide.

Means for Solving the Problems

[0006] The composition according to one aspect of the present invention contains an ethylene·α-olefin·non-conjugated polyene copolymer (A) described below, carbon black (B), and an organic peroxide (C). In the above composition, the content of carbon black (B) is 5 to 150 parts by mass and the content of the organic peroxide (C) is 0.01 part by mass or more and less than 2.0 parts by mass with respect to 100 parts by mass of the copolymer (A).

Effects of the Invention

[0007] According to the present invention, by using a specific copolymer as the ethylene·α-olefin·non-conjugated polyene copolymer, it is possible to provide a composition that can form a molded article having excellent cold resistance despite a low content of the organic peroxide.

Modes for Carrying Out the Invention

[0008] In this specification, the numerical range n1 to n2 means n1 or more and n2 or less when n1 < n2, and means n2 or more and n1 or less when n1 > n2. In this specification, when a lower limit value and an upper limit value are each described a plurality of times in the description of an element, a numerical range formed by combining a value arbitrarily selected from the described lower limit values and a value arbitrarily selected from the described upper limit values is also described.

[0009] [Composition] The composition according to one aspect of the present invention (hereinafter also referred to as "this composition") is an ethylene·α-olefin·non-conjugated polyene copolymer (A), carbon black (B), an organic peroxide (C), and contains.

[0010] <Ethylene·α-olefin·non-conjugated polyene copolymer (A)> Ethylene·α-olefin·non-conjugated polyene copolymer (A) (hereinafter also referred to as "copolymer (A)") has a structural unit derived from ethylene [A1], a structural unit derived from an α-olefin [A2] having 4 to 20 carbon atoms, and a structural unit derived from a non-conjugated polyene [A3]. The non-conjugated polyene [A3] contains two or more partial structures selected from the group consisting of the following formulas (I) and (II) in one molecule in total.

[0011]

Chemical formula

[0012] Copolymer (A) further satisfies the requirements (1) to (4) described below.

[0013] Examples of the α-olefin [A2] having 4 to 20 carbon atoms include α-olefins having a straight-chain structure without a side chain, such as 1-butene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-nonadecene, and 1-eicosene; and α-olefins having a side chain, such as 4-methyl-1-pentene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1-tetradecene.

[0014] The structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms contains a structural unit derived from 1-butene. That is, copolymer (A) has at least a structural unit derived from 1-butene as the structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms. Therefore, at least 1-butene is used as the α-olefin [A2].

[0015] As the α-olefin [A2], 1-butene can be used alone or two or more kinds including 1-butene can be used. When two or more kinds including 1-butene are used as the α-olefin [A2], as the α-olefin used together with 1-butene, α-olefins having 5 to 10 carbon atoms are preferable, and 1-hexene and 1-octene are more preferable.

[0016] Ethylene·propylene·non-conjugated polyene copolymer in which the α-olefin is propylene may have limited applications because its rubber elasticity at low temperatures is insufficient. Since the copolymer (A) has structural units derived from α-olefins [A2] having 4 to 20 carbon atoms, it has excellent rubber elasticity at low temperatures.

[0017] Examples of the non-conjugated polyene [A3] include 5-vinyl-2-norbornene (VNB), norbornadiene, 1,4-hexadiene, and dicyclopentadiene.

[0018] The structural units derived from the non-conjugated polyene [A3] include the structural units derived from 5-vinyl-2-norbornene (VNB). That is, the copolymer (A) has at least the structural units derived from VNB as the structural units derived from the non-conjugated polyene [A3]. Therefore, at least VNB is used as the non-conjugated polyene [A3].

[0019] As the non-conjugated polyene [A3], VNB can be used alone or two or more kinds including VNB can be used. VNB is easily available. The copolymer having the structural units derived from VNB has good crosslinkability with the organic peroxide (C), and the molded article obtained from the above composition tends to have excellent physical properties such as cold resistance and heat resistance. As the non-conjugated polyene [A3], it is preferable to use VNB alone. That is, the copolymer (A) preferably has only the structural units derived from VNB as the structural units derived from the non-conjugated polyene [A3].

[0020] In the copolymer (A), the total content of the structural units derived from the polymerizable monomers is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, even more preferably 95 mol% or more, and particularly preferably 98 mol% or more, based on 100 mol% of the total amount of the structural units derived from the polymerizable monomers. In the present specification, the content of each structural unit in the copolymer (A) can be calculated from the NMR spectrum.

[0021] In addition to the structural units derived from ethylene [A1], the α-olefin having 4 to 20 carbon atoms [A2], and the non-conjugated polyene [A3], the copolymer (A) may further have a structural unit derived from a non-conjugated polyene [A4]. The non-conjugated polyene [A4] contains only one partial structure selected from the group consisting of the above formulas (I) and (II) in one molecule.

[0022] Examples of the non-conjugated polyene [A4] include, for example, 5-ethylidene-2-norbornene (ENB), 5-methylene-2-norbornene, 5-(2-propenyl)-2-norbornene, 5-(3-butenyl)-2-norbornene, 5-(1-methyl-2-propenyl)-2-norbornene, 5-(4-pentenyl)-2-norbornene, 5-(1-methyl-3-butenyl)-2-norbornene, 5-(5-hexenyl)-2-norbornene, 5-(1-methyl-4-pentenyl)-2-norbornene, 5-(2,3-dimethyl-3-butenyl)-2-norbornene, 5-(2-ethyl-3-butenyl)-2-norbornene, 5-(6-heptenyl)-2-norbornene, 5-(3-methyl-5-hexenyl)-2-norbornene, 5-(3,4-dimethyl-4-pentenyl)-2-norbornene, 5-(3-ethyl-4-pentenyl)-2-norbornene, 5-(7-octenyl)-2-norbornene, 5-(2-methyl-6-heptenyl)-2-norbornene, 5-(1,2-dimethyl-5-hexenyl)-2-norbornene, 5-(5-ethyl-5-hexenyl)-2-norbornene, and 5-(1,2,3-trimethyl-4-pentenyl)-2-norbornene.

[0023] ENB is highly available. Copolymers having structural units derived from ENB are easy to control the crosslinking rate during crosslinking with the organic peroxide (C), and the molded article obtained from the above composition tends to have good mechanical properties. Therefore, as the non-conjugated polyene [A4], ENB is preferred. That is, the copolymer (A) may have a structural unit derived from ENB as a structural unit derived from the non-conjugated polyene [A4].

[0024] The non-conjugated polyene [A4] may be one kind or two or more kinds.

[0025] As the ethylene [A1], ethylene derived from biomass may be used. As the α-olefin [A2] having 4 to 20 carbon atoms, α-olefin derived from biomass may be used. As the non-conjugated polyenes [A3] and [A4], non-conjugated polyenes derived from biomass may be used respectively.

[0026] The Mooney viscosity ML(1+4)100°C of the copolymer (A) is preferably 5 to 60, more preferably 20 to 60, still more preferably 20 to 50. A copolymer having a Mooney viscosity ML(1+4)100°C within the above range is excellent in roll processability even in a high-hardness oil-free compounding, and also exhibits good post-treatment (ribbon handling property) and tends to have excellent rubber physical properties. The Mooney viscosity ML(1+4)100°C of the copolymer (A) is measured using a Mooney viscometer in accordance with JIS K 6300-1(2013).

[0027] This composition may contain one or more copolymers (A). The content ratio of the copolymer (A) in this composition is preferably 20 to 90% by mass, more preferably 30 to 80% by mass, still more preferably 40 to 70% by mass in 100% by mass of this composition. Such a composition tends to be able to form a molded article excellent in rubber physical properties such as hardness and flexibility.

[0028] ≪Requirement (1)≫ Requirement (1): The molar ratio ([A1] / [A2]) of the content of the structural unit derived from ethylene [A1] to the content of the structural unit derived from an α-olefin [A2] having 4 to 20 carbon atoms is 40 / 60 to 90 / 10. A copolymer (A) having a molar ratio within this range is excellent in the balance between rubber elasticity at low temperatures and tensile strength at room temperature.

[0029] The lower limit value of the molar ratio ([A1] / [A2]) is preferably 45 / 55, more preferably 50 / 50, still more preferably 55 / 45, even more preferably 60 / 40, particularly preferably 65 / 35. The upper limit value of the molar ratio ([A1] / [A2]) is preferably 80 / 20, more preferably 75 / 25, still more preferably 70 / 30.

[0030] ≪Requirement (2)≫ Requirement (2): When the content ratio of the structural unit derived from the non-conjugated polyene [A3] is 0.1 to 6.0 mol% based on the total content of the structural unit derived from ethylene [A1], the structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms, and the structural unit derived from the non-conjugated polyene [A3] being 100 mol%. The copolymer (A) in which the content ratio is within the above range is excellent in crosslinkability and flexibility.

[0031] The lower limit value of the content ratio of the structural unit derived from the non-conjugated polyene [A3] is preferably 0.2 mol%, more preferably 0.3 mol%. The upper limit value of the content ratio of the structural unit derived from the non-conjugated polyene [A3] is preferably 4.0 mol%, more preferably 3.0 mol%, still more preferably 2.0 mol%, and particularly preferably 0.7 mol%. The copolymer (A) in which the content ratio is within the above range is excellent in crosslinkability, flexibility and low temperature properties.

[0032] ≪Requirement (3)≫ Requirement (3): The B value represented by the following formula (i) is 1.20 or more. B value = ([EX] + 2[Y]) / 〔2×[E]×([X] + [Y])〕 … Formula (i)

[0033] In formula (i), [E] represents the mole fraction of the structural unit derived from ethylene [A1], [X] represents the mole fraction of the structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms, [Y] represents the mole fraction of the structural unit derived from the non-conjugated polyene [A3], and [EX] represents the ethylene [A1] - α-olefin [A2] having 4 to 20 carbon atoms dyad chain fraction. [E], [X], [Y], and [EX] in formula (i) are 13 measured by C-NMR spectrum and can be determined based on the reports of J.C. Randall [Macromolecules, 15, 353 (1982)], J. Ray [Macromolecules, 10, 773 (1977)], etc.

[0034] The B value is an index indicating the randomness of the copolymerization monomer chain distribution in the copolymer (A). Copolymers with a B value of less than 1.20 tend to have a large compression set at low temperatures. Copolymers with a B value of 1.20 or more tend to have a small compression set at low temperatures.

[0035] The B value is preferably from 1.20 to 1.80, more preferably from 1.22 to 1.60, still more preferably from 1.24 to 1.50, and particularly preferably from 1.30 to 1.45. Copolymers with a B value within the above range tend to have an excellent balance between rubber elasticity at low temperatures and tensile strength at room temperature.

[0036] ≪Requirement (4)≫ Requirement (4): The number of branch points BrNo per molecular chain obtained using 3D-gel permeation chromatography (GPC) satisfies the following formula (ii). BrNo ≧ 0.5 … Formula (ii)

[0037] The number of branch points BrNo per molecular chain can be determined by a structural analysis method using 3D-GPC. In this specification, specifically, BrNo is determined by the method described in the Examples section below.

[0038] The copolymer (A) preferably satisfies the following formula (ii-1). BrNo ≧ 0.8 … Formula (ii-1)

[0039] Copolymers in which the number of branch points per molecular chain satisfies formula (ii) or (ii-1) tend to have excellent crosslinking speed even when the amount of the organic peroxide (C) used is small. A crosslinked molded article obtained using such a copolymer tends to have excellent cold resistance and mechanical properties.

[0040] The copolymer (A) more preferably satisfies the following formula (ii-2). 3.0 ≧ BrNo … Formula (ii-2)

[0041] The copolymer in which the number of branch points per molecular chain satisfies the formula (ii-2) has a small compression set at low temperatures and also tends to have an excellent balance between rubber elasticity at low temperatures and tensile strength at room temperature.

[0042] The copolymer (A) preferably satisfies any one or two or more of the following requirements (5) to (8). The copolymer (A) more preferably satisfies any two or more of the requirements (5) to (8), still more preferably satisfies any three or more of the requirements (5) to (8), and most preferably satisfies all of the requirements (5) to (8).

[0043] ≪Requirement (5)≫ Requirement (5): The weight average molecular weight (Mw) of the copolymer (A), the weight fraction of the structural unit derived from the non-conjugated polyene [A3] ([weight fraction of [A3] (mass%)]), and the molecular weight of the non-conjugated polyene [A3] ([molecular weight of [A3]]) satisfy the following formula (iii).

[0044] 4.5 ≦ Mw × weight fraction of [A3] / 100 / molecular weight of [A3] ≦ 80 …Formula (iii)

[0045] The weight average molecular weight (Mw) of the copolymer (A) can be determined as a polystyrene-equivalent value measured by gel permeation chromatography (GPC). In this specification, specifically, Mw is determined by the method described in the Examples section below using 3D-GPC.

[0046] The copolymer (A) more preferably satisfies the following formula (iii-1). 4.5 ≦ Mw × weight fraction of [A3] / 100 / molecular weight of [A3] ≦ 60 …Formula (iii-1)

[0047] When "weight fraction of Mw × [A3] / 100 / molecular weight of [A3]" satisfies formula (iii) or (iii-1), the content of the structural unit derived from non-conjugated polyene [A3] such as VNB is appropriate, and the crosslinking degree tends to be appropriate. Such a copolymer has excellent crosslinking speed, and the molded body after crosslinking has excellent mechanical properties.

[0048] ≪Requirement (6)≫ Requirement (6): Ratio P(η * (ω=0.1) / η * (ω=100) ) and the intrinsic viscosity [η] of copolymer (A) and the weight fraction of the above [A3] satisfy the following formula (iv). η * (ω=0.1) represents the complex viscosity (Pa·sec) at a frequency ω = 0.1 rad / s. η * (ω=100) represents the complex viscosity (Pa·sec) at a frequency ω = 100 rad / s. These complex viscosities are obtained by linear viscoelastic measurement (190 °C) using a rheometer. P / ([η] 2.9 ) ≤ weight fraction of [A3] × 6 … Formula (iv)

[0049] The complex viscosity η * (ω=0.1) and the complex viscosity η * (ω=100) The ratio P(η * (ω=0.1) / η * (ω=100) ) represents the frequency dependence of viscosity. P / ([η] 2.9 ) on the left side of formula (iv) shows a tendency to have a high value when there are many long-chain branches, although it is affected by short-chain branches and molecular weight. Generally, ethylene·α-olefin·non-conjugated polyene copolymers tend to contain more long-chain branches as they contain more structural units derived from non-conjugated polyenes. Copolymer (A) is considered to be able to satisfy formula (iv) because it has fewer long-chain branches than conventionally known ethylene·α-olefin·non-conjugated polyene copolymers.

[0050] Copolymer (A) more preferably satisfies the following formula (iv-1). P / ( [η] 2.9 ) ≤ weight fraction of [A3] × 5.7 … Equation (iv-1)

[0051] The ratio P (P value) was determined by measuring at 190 °C, a strain of 1.0%, and varying the frequency using a viscoelasticity measuring device Ares (manufactured by Rheometric Scientific). The ratio (η * ratio) was obtained from the complex viscosity at 0.1 rad / s and the complex viscosity at 100 rad / s. The P value is preferably 5 to 50, more preferably 5 to 30, still more preferably 10 to 22, even more preferably 13 to 19, and particularly preferably 15 to 17.

[0052] The intrinsic viscosity [η] of the copolymer (A) in Requirement (6) means the value measured in decalin at 135 °C. The intrinsic viscosity [η] of the copolymer (A) is preferably 2.5 dl / g or less, more preferably 2.0 dl / g or less, still more preferably 1.85 dl / g or less, and particularly preferably 1.75 dl / g or less. There is no particular limitation on the lower limit value of the intrinsic viscosity [η] of the copolymer (A). The intrinsic viscosity [η] of the copolymer (A) is, for example, 0.01 dl / g or more.

[0053] ≪Requirement (7)≫ Requirement (7): η * (ω=0.01) and η * (ω=10) and the apparent iodine value derived from the non-conjugated polyene [A3] satisfy the following formula (v). η * (ω=0.01) represents the complex viscosity (Pa·sec) at a frequency ω = 0.01 rad / s. η * (ω=10) represents the complex viscosity (Pa·sec) at a frequency ω = 10 rad / s. These complex viscosities are obtained by linear viscoelasticity measurement (190 °C) using a rheometer. Log{η * (ω=0.01)} / Log{η * (ω=10)} ≤ 0.0753 × {apparent iodine value derived from the non-conjugated polyene [A3]} + 1.42 … Equation (v)

[0054] Complex viscosity η * (ω=0.01) and complex viscosity η * (ω=10) except for the measurement frequency, is the complex viscosity η in requirement (6) * (ω=0.1) and complex viscosity η * (ω=100) and is determined in the same manner as The apparent iodine value derived from the non-conjugated polyene [A3] is determined by the following formula Apparent iodine value derived from [A3] = weight fraction of [A3] × 253.81 / molecular weight of [A3]

[0055] In formula (v), the left side represents the shear rate dependence which is an index of the long-chain branching amount, and the right side represents an index of the content of the non-conjugated polyene [A3] that has not been consumed as long-chain branches during polymerization. When the copolymer (A) satisfies requirement (7) and satisfies formula (v), it is preferable because the degree of long-chain branching is not too high. On the other hand, when the polymer (A) does not satisfy formula (v), it indicates that a large proportion of the copolymerized non-conjugated polyene [A3] has been consumed in the formation of long-chain branches

[0056] ≪Requirement (8)≫ Requirement (8): The glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) is -65°C or lower. The above Tg is preferably -67°C or lower, more preferably -70°C or lower. When Tg is within the above range, the resulting molded article has excellent low-temperature properties Specifically, Tg is determined by the method described in the Examples section below

[0057] ≪Method for producing copolymer (A)≫ The copolymer (A) can be obtained by various known production methods, for example, by a conventionally known production method using a metallocene catalyst containing a metallocene compound as one component of the catalyst. As the metallocene catalyst and the production method using the catalyst, for example, the examples described in International Publication No. 2015 / 122415 (especially paragraphs

[0249] to

[0320] ) can be adopted. Specifically, the copolymer (A) is obtained by copolymerizing at least ethylene [A1], an α-olefin [A2] having 4 to 20 carbon atoms, and a non-conjugated polyene [A3] in the presence of a metallocene catalyst, as described in the Examples section below.

[0058] <Carbon black (B)> Carbon black (B) is a kind of known rubber reinforcing agent compounded in the rubber composition, and is usually an inorganic substance called carbon black. Examples of the carbon black (B) include SRF, GPF, FEF, MAF, HAF, ISAF, SAF, FT, and MT. The surface of the carbon black may be treated with a silane coupling agent. This composition may contain one or more kinds of carbon black (B).

[0059] The content of the carbon black (B) in this composition is preferably 5 to 150 parts by mass, more preferably 5 to 140 parts by mass, still more preferably 10 to 120 parts by mass, particularly preferably 15 to 100 parts by mass, and most preferably 20 to 80 parts by mass with respect to 100 parts by mass of the copolymer (A).

[0060] <Organic peroxide (C)> The organic peroxide (C) is a kind of crosslinking agent. Examples of the organic peroxide (C) include dicumyl peroxide, di-tert-butyl peroxide, 2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and tert-butyl cumyl peroxide.

[0061] Preferred examples of the organic peroxide (C) include dicumyl peroxide, 2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexyne-3, 1,3-bis(tert-butylperoxyisopropyl)benzene, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, and n-butyl-4,4-bis(tert-butylperoxy)valerate. The composition may contain one or more organic peroxides (C).

[0062] The content of the organic peroxide (C) in the composition is 0.01 part by mass or more and less than 2.0 parts by mass with respect to 100 parts by mass of the copolymer (A). Since the composition contains a specific copolymer (A) as an ethylene·α-olefin·non-conjugated polyene copolymer, a molded article excellent in physical properties such as cold resistance can be formed even though the content of the organic peroxide (C) is small. Therefore, the composition can be produced at low cost, for example. The content of the organic peroxide (C) in this composition is preferably 1.9 parts by mass or less, more preferably 1.8 parts by mass or less, still more preferably 1.7 parts by mass or less, and for example, may be less than 1.0 part by mass, based on 100 parts by mass of the copolymer (A). The content of the organic peroxide (C) in this composition is preferably 0.05 part by mass or more, more preferably 0.1 part by mass or more, based on 100 parts by mass of the copolymer (A).

[0063] <Other components> This composition may further contain components other than the above-described components (hereinafter also referred to as "other components") according to the purpose. Examples of other components include polymers other than the copolymer (A), crosslinking aids, vulcanization accelerators, vulcanization aids, softeners, inorganic fillers other than carbon black (B), processing aids, activators, moisture absorbers, antioxidants, heat stabilizers, weather stabilizers, antistatic agents, colorants, lubricants, thickeners, foaming agents, and foaming aids. Each of the other components may be used alone or in combination of two or more.

[0064] ≪Polymer other than copolymer (A)≫ This composition may contain a polymer other than the copolymer (A) (hereinafter also referred to as "other polymer"). Examples of other polymers include other polymers that require crosslinking and other polymers that do not require crosslinking.

[0065] Examples of other polymers that require crosslinking include crosslinkable rubbers. Examples of crosslinkable rubbers include natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, acrylic rubber, silicone rubber, fluorine rubber, and urethane rubber.

[0066] Examples of other polymers that do not require crosslinking include elastomers. Examples of elastomers include styrenic thermoplastic elastomers (TPS) such as block copolymers of styrene and butadiene (SBS), polystyrene-poly(ethylene-butylene)-polystyrene (SEBS), and polystyrene-poly(ethylene-propylene)-polystyrene (SEPS), olefinic thermoplastic elastomers (TPO), vinyl chloride-based elastomers (TPVC), ester-based thermoplastic elastomers (TPC), amide-based thermoplastic elastomers (TPA), urethane-based thermoplastic elastomers (TPU), and other thermoplastic elastomers (TPZ).

[0067] When the composition contains other polymers, the content of the other polymers in the composition is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, based on 100 parts by mass of the copolymer (A).

[0068] ≪Crosslinking Aid≫ The composition may contain a crosslinking aid together with the organic peroxide (C). Examples of the crosslinking aid include sulfur; quinone dioxime-based crosslinking aids such as p-quinone dioxime; (meth)acrylic crosslinking aids such as ethylene glycol di(meth)acrylate and trimethylolpropane tri(meth)acrylate; allyl crosslinking aids such as diallyl phthalate and triallyl isocyanurate; maleimide-based crosslinking aids; divinylbenzene; and metal oxides such as zinc oxide and magnesium oxide. As the crosslinking aid, zinc oxide is preferred, and activated zinc white, which is zinc oxide with a large specific surface area, is more preferred.

[0069] When the composition contains a crosslinking aid, the content of the crosslinking aid in the composition is preferably 0.5 to 100 moles, more preferably 5 to 50 moles, and even more preferably 10 to 30 moles, based on 1 mole of the organic peroxide (C).

[0070] ≪Softening Agent≫ Examples of the softening agent include petroleum-based softening agents such as process oil, lubricating oil, paraffin oil, liquid paraffin, petroleum asphalt, and petrolatum; coal-tar-based softening agents such as coal tar; fatty oil-based softening agents such as castor oil, linseed oil, rapeseed oil, soybean oil, and coconut oil; waxes such as beeswax and carnauba wax; naphthenic acid, pine oil, rosin or its derivatives; synthetic polymer substances such as terpene resin, petroleum resin, and coumarone-indene resin; ester-based softening agents such as dioctyl phthalate and dioctyl adipate; and others such as microcrystalline wax, liquid polybutadiene, modified liquid polybutadiene, hydrocarbon-based synthetic lubricating oil, tall oil, and factice. Among these, petroleum-based softening agents are preferred, and process oil is particularly preferred.

[0071] When the composition contains a softening agent, the content of the softening agent is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, based on 100 parts by mass of the copolymer (A).

[0072] ≪Inorganic filler≫ Examples of the inorganic filler other than carbon black (B) include light calcium carbonate, heavy calcium carbonate, talc, and clay. Among these, heavy calcium carbonate is preferred.

[0073] When the composition contains an inorganic filler other than carbon black (B), the content of the inorganic filler is preferably 2 to 50 parts by mass, more preferably 5 to 50 parts by mass, based on 100 parts by mass of the copolymer (A). A composition having the content of the inorganic filler within the above range can form, for example, a fuel cell gasket excellent in kneading processability and mechanical properties.

[0074] ≪Processing aid≫ As processing aids, for example, those generally compounded with rubber as processing aids can be widely used. Examples of the processing aids include fatty acids such as ricinoleic acid, stearic acid, palmitic acid, and lauric acid; fatty acid salts such as barium stearate, zinc stearate, and calcium stearate; and fatty acid esters. Among these, stearic acid is preferred.

[0075] When the composition contains a processing aid, the content of the processing aid is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, still more preferably 4 parts by mass or less, and particularly preferably 2 parts by mass or less with respect to 100 parts by mass of the copolymer (A).

[0076] ≪Activator≫ Examples of the activator include amines such as di-n-butylamine, dicyclohexylamine, and monoethanolamine; activators such as diethylene glycol, polyethylene glycol, lecithin, triallyl trimellitate, and zinc compounds of aliphatic carboxylic acids or aromatic carboxylic acids; zinc peroxide preparations; and octadecyltrimethylammonium bromide, synthetic hydrotalcite, and special quaternary ammonium compounds.

[0077] When the composition contains an activator, the content of the activator is preferably 0.2 to 10 parts by mass, more preferably 0.3 to 5 parts by mass with respect to 100 parts by mass of the copolymer (A).

[0078] ≪Humectant≫ Examples of the humectant include calcium oxide, silica gel, sodium sulfate, molecular sieve, zeolite, and white carbon. When the composition contains a humectant, the content of the humectant is preferably 0.5 to 15 parts by mass, more preferably 1.0 to 12 parts by mass with respect to 100 parts by mass of the copolymer (A).

[0079] ≪Antioxidant≫ Examples of the anti-aging agent include amine-based anti-aging agents, phenol-based anti-aging agents, thioether-based anti-aging agents, dithiocarbamate-based anti-aging agents, and sulfur-based anti-aging agents. Specifically, as the anti-aging agent, aromatic secondary amine-based anti-aging agents such as phenylbutylamine and N,N-di-2-naphthyl-p-phenylenediamine; phenol-based anti-aging agents such as dibutylhydroxytoluene and tetrakis[methylene(3,5-di-t-butyl-4-hydroxy)hydrocinnamate]methane; thioether-based anti-aging agents such as bis[2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylphenyl]sulfide; dithiocarbamate-based anti-aging agents such as nickel dibutyldithiocarbamate; and sulfur-based anti-aging agents such as 2-mercaptobenzoyl imidazole, 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, dilauryl thiodipropionate, and distearyl thiodipropionate can be mentioned.

[0080] When the composition contains an anti-aging agent, the content of the anti-aging agent is preferably 0.5 to 7 parts by mass, more preferably 0.5 to 6 parts by mass, based on 100 parts by mass of the copolymer (A).

[0081] <<Blowing Agent>> The molded article (e.g., fuel cell gasket) formed using this composition may be a non-foamed body or a foamed body. When the molded article is a foamed body, it is preferable that this composition contains a blowing agent.

[0082] As the foaming agent, any commercially available foaming agent can be preferably used. Examples of the foaming agent include inorganic foaming agents such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, and ammonium nitrite; nitroso compounds such as N,N'-dinitrosoterephthalamide and N,N'-dinitrosopentamethylenetetramine; azo compounds such as azodicarbonamide, azobisisobutyronitrile, azocyclohexylnitrile, azodiaminobenzene, and barium azodicarboxylate; sulfonylhydrazide compounds such as benzenesulfonylhydrazide, toluenesulfonylhydrazide, and p,p'-oxybis(benzenesulfonylhydrazide) diphenylsulfone-3,3'-disulfonylhydrazide; and azide compounds such as calcium azide, 4,4'-diphenyldisulfonyl azide, and paratoluenemalonyl azide. Among these, azo compounds, sulfonylhydrazide compounds, and azide compounds are preferred.

[0083] When the composition contains a foaming agent, the content of the foaming agent is preferably 0.1 to 30 parts by mass, more preferably 0.2 to 20 parts by mass, based on 100 parts by mass of the copolymer (A).

[0084] ≪Foaming Aid≫ The composition may contain a foaming aid together with the foaming agent. The addition of the foaming aid is effective for adjusting the decomposition temperature of the foaming agent and homogenizing the bubbles. Examples of the foaming aid include organic acids such as salicylic acid, phthalic acid, stearic acid, and oxalic acid; urea; and derivatives thereof.

[0085] When the composition contains a foaming aid, the content of the foaming aid is preferably 1 to 100 parts by mass, more preferably 2 to 80 parts by mass, based on 100 parts by mass of the foaming agent.

[0086] <Manufacturing Method of the Composition> This composition can be prepared by kneading a copolymer (A), carbon black (B), an organic peroxide (C), and other components to be compounded as needed, at a desired temperature using a kneader such as a mixer, a kneader, or a roll.

[0087] Specifically, this composition can be prepared as follows. The copolymer (A), carbon black (B), and other components used as needed are kneaded at a predetermined temperature and time, for example, at 80 to 200 °C for 3 to 30 minutes, using a conventionally known kneader such as a mixer or a kneader. To the obtained kneaded product, the organic peroxide (C) and other components used as needed are added, and kneaded at a predetermined temperature and time, for example, at a roll temperature of 30 to 80 °C for 1 to 30 minutes using a roll. In this way, this composition can be prepared.

[0088] <Properties of this composition> Even when the content of the organic peroxide (C) as a crosslinking agent is small, this composition can form a molded article having excellent cold resistance (low-temperature properties, for example, low-temperature resilience (TR) properties). For example, the TR10 of a sheet-like test piece with a thickness of 2 mm obtained by pressing this composition under the conditions of 180 °C for 10 minutes is preferably -60 °C or lower, more preferably -60 to -80 °C, and even more preferably -60 to -70 °C. TR10 is measured in accordance with the TR test (low-temperature resilience test) of JIS K 6261-4 (2017). Details of the measurement conditions are described in the Examples section.

[0089] Even when the content of the organic peroxide (C) as a crosslinking agent is small, this composition can form a molded article having small compression set at high and low temperatures. Even when the content of the organic peroxide (C) as a crosslinking agent is small, this composition can exhibit excellent crosslinkability (for example, crosslinking rate). Therefore, this composition is excellent in the productivity of crosslinked molded articles.

[0090] The Mooney viscosity ML(1+4) at 100 °C of this composition is preferably from 1 to 200, more preferably from 30 to 150, still more preferably from 50 to 120, and particularly preferably from 70 to 100. A composition having a Mooney viscosity ML(1+4) at 100 °C within the above range has good roll processability. The Mooney viscosity is measured using a Mooney viscometer in accordance with JIS K 6300-1 (2013).

[0091] The Mooney viscosity ML(1+4) at 125 °C of this composition is preferably from 1 to 100, more preferably from 20 to 90, still more preferably from 30 to 70, and particularly preferably from 40 to 50. A composition having a Mooney viscosity ML(1+4) at 125 °C within the above range has good roll processability.

[0092] Since this composition has a low content of the organic peroxide (C) as a crosslinking agent, a molded article excellent in tensile stress can be formed. For example, a 2 mm thick sheet obtained by subjecting this composition to press treatment under the conditions of 180 °C for 10 minutes is punched out to prepare dumbbell-shaped No. 3 test pieces described in JIS K 6251 (2023). When a tensile test is performed on the above test piece under the conditions of a measurement temperature of 25 °C and a tensile speed of 500 mm / min in accordance with the method specified in Paragraph 13 of JIS K 6251, the tensile stress (100% modulus (M100)) when the elongation rate is 100% is preferably 5.0 MPa or less, more preferably 4.5 MPa or less, still more preferably 3.5 MPa or less, even more preferably 3.0 MPa or less, and particularly preferably 2.5 MPa or less. The lower limit value of the above M100 is not particularly limited, but may be, for example, 0.1 MPa. Further, when a tensile test is performed on the above test piece under the conditions of a measurement temperature of 25 °C and a tensile speed of 500 mm / min in accordance with the method specified in Paragraph 13 of JIS K 6251, the elongation at break (Eb) is preferably 210% or more, more preferably 230% or more, still more preferably 300% or more, even more preferably 350% or more, and particularly preferably 400% or more. The upper limit value of the above Eb is not particularly limited, but may be, for example, 1000%.

[0093] Since the content of the organic peroxide (C) as a crosslinking agent in this composition is small, a molded article with a low crosslinking density can be formed. For example, the effective network chain density (crosslinking density) ν of a sheet-like test piece with a thickness of 2 mm obtained by pressing this composition under the conditions of 180 °C for 10 minutes is preferably 1.5×10 19 pieces / cm 3 or more and 30×10 19 pieces / cm 3 or less, more preferably 4×10 19 pieces / cm 3 or more and 28×10 19 pieces / cm 3 or less, even more preferably 6×10 19 pieces / cm 3 or more and 25×10 19 pieces / cm 3 or less. The above-mentioned effective network chain density is calculated by the Flory-Rehner equation after swelling the above-mentioned sheet-like test piece by immersing it in toluene at 37 °C for 72 hours in accordance with JIS K 6258 (2016).

[0094] <Use of this composition> This composition is suitable for use as a fuel cell gasket. By using this composition, it is possible to obtain a fuel cell gasket that is excellent in low-temperature flexibility compared to the case of using conventional EPDM, and it is possible to obtain a fuel cell gasket that is excellent in cold resistance compared to the case of using silicone rubber.

[0095] [Molded article] The molded article according to one aspect of the present invention is formed from this composition. The molded article is, for example, a crosslinked molded article or a crosslinked foam. The molded article can be used for various applications.

[0096] Examples of the uses of the above-formed article include, for example, rubber for tires, O-rings, industrial rolls, packings (e.g., capacitor packings), gaskets (e.g., fuel cell gaskets), belts (e.g., heat insulation belts, copier belts), hoses (e.g., water hoses, brake reservoir hoses, radiator hoses), anti-vibration rubbers, sponges (e.g., weatherstrip sponges, heat insulation sponges, protection sponges, micro-foamed sponges), cables (ignition cables, cab tire cables, high-tension cables), wire coating materials (high-voltage wire coating materials, low-voltage wire coating materials, marine wire coating materials), glass run channels, color skin materials, paper feed rolls, roofing sheets, and all-solid-state batteries.

[0097] Examples of the method for manufacturing the above-formed article include, for example, a method of molding this composition (uncrosslinked composition) into a desired shape and simultaneously or after the molding, crosslinking the composition.

[0098] In the above molding, for example, using a molding machine, the present composition is molded into a desired shape. Examples of the molding machine include, for example, an extrusion molding machine, calendar rolls, a press molding machine, an injection molding machine, and a transfer molding machine. The shape of the molded article is not particularly limited, and examples include a sheet shape, a plate shape, and a ring shape.

[0099] Examples of the method for crosslinking the present composition include, for example, a method of crosslinking the present composition by heating, and a method of crosslinking the present composition by irradiating it with an electron beam. In the crosslinking treatment, a mold may or may not be used. When not using a mold, it is preferable to perform the molding and the crosslinking treatment continuously.

[0100] When heat treatment is employed as the crosslinking treatment, the heating temperature is preferably 120 to 270 °C, and the heating time is preferably 1 to 30 minutes. Examples of the heating method include methods using means such as hot air, glass bead fluidized bed, ultra-high frequency electromagnetic wave (UHF), and steam. When electron beam irradiation treatment is employed as the crosslinking treatment, the composition formed into a predetermined shape may be irradiated with an electron beam having an energy of preferably 0.1 to 10 MeV, more preferably 0.3 to 2 MeV. The absorbed dose of the electron beam is preferably 0.5 to 35 Mrad, more preferably 0.5 to 10 Mrad.

[0101] The above-mentioned molded body can be preferably used, for example, as a fuel cell gasket. A fuel cell gasket is a rubber component that suppresses leakage of hydrogen, oxygen, or water, for example, inside a fuel cell (FC) stack. The above-mentioned molded body can be more preferably used as a fuel cell gasket used in a hydrogen line. At a hydrogen station that supplies hydrogen to a fuel cell vehicle (FCV) or the like, there are a large number of hydrogen lines through which hydrogen passes. The above-mentioned fuel cell gasket can be used as a fuel cell gasket used in such a hydrogen line.

[0102] At a hydrogen station, in order to store a large amount of hydrogen, it is necessary to store hydrogen in a compressor at high pressure. When supplying hydrogen from a hydrogen station, it is necessary to send out hydrogen at high pressure and high speed, and at this time, the temperature of hydrogen rises. In order not to raise the temperature inside the hydrogen tank of a fuel cell vehicle or the like too much, it is necessary to store hydrogen at a low temperature (for example, about -40 °C) at a hydrogen station. For this reason, the fuel cell gasket used in a hydrogen line is required to have sealing performance at low temperatures. The fuel cell gasket of the present invention is excellent in, for example, low-temperature characteristics and mechanical properties (strength and elongation) at normal temperature, and can be suitably used for a hydrogen line.

[0103] [Aspect Example] The present invention relates to, for example, the following [1] to [7]. A composition, comprising an ethylene·α-olefin·non-conjugated polyene copolymer (A), carbon black (B), and an organic peroxide (C), wherein the copolymer (A) has structural units derived from ethylene [A1], structural units derived from an α-olefin [A2] having 4 to 20 carbon atoms, and structural units derived from a non-conjugated polyene [A3] containing two or more partial structures selected from the group consisting of the following formulas (I) and (II) in one molecule, and satisfies the following requirements (1) to (4). The structural units derived from the α-olefin [A2] having 4 to 20 carbon atoms include structural units derived from 1-butene, and the structural units derived from the non-conjugated polyene [A3] include structural units derived from 5-vinyl-2-norbornene. In the composition, the content of the carbon black (B) is 5 to 150 parts by mass, and the content of the organic peroxide (C) is 0.01 part by mass or more and less than 2.0 parts by mass, based on 100 parts by mass of the copolymer (A): [Chemical formula] Requirement (1): The molar ratio ([A1] / [A2]) of the content of the structural units derived from ethylene [A1] to the content of the structural units derived from the α-olefin [A2] having 4 to 20 carbon atoms is 40 / 60 to 90 / 10; Requirement (2): The content ratio of the structural units derived from the non-conjugated polyene [A3] is 0.1 to 6.0 mol% when the total content of the structural units derived from [A1], the structural units derived from [A2], and the structural units derived from [A3] is 100 mol%; Requirement (3): The B value represented by the following formula (i) is 1.20 or more; B value = ([EX] + 2[Y]) / [2×[E]×([X] + [Y])] … formula (i) [In formula (i), [E] represents the mole fraction of the structural units derived from ethylene [A1], [X] represents the mole fraction of the structural units derived from the α-olefin [A2] having 4 to 20 carbon atoms, [Y] represents the mole fraction of the structural units derived from the non-conjugated polyene [A3], and [EX] represents the ethylene [A1]-α-olefin [A2] having 4 to 20 carbon atoms dyad chain fraction.] Requirement (4): The number of branch points BrNo per molecular chain obtained using 3D-gel permeation chromatography (GPC) satisfies the following formula (ii). BrNo ≧ 0.5 … Formula (ii) [2] For the sheet-shaped test piece with a thickness of 2 mm obtained by press-treating the composition under the conditions of 180 °C for 10 minutes, the TR10 measured in accordance with the TR test of JIS K 6261-4 (2017) is -60 °C or lower, and the composition described in the above [1]. [3] The composition described in the above [1] or [2], wherein the copolymer (A) satisfies one or more of the following requirements (5) to (8): Requirement (5): The weight-average molecular weight (Mw) of the copolymer (A), the weight fraction of the structural unit derived from the non-conjugated polyene [A3] ([weight fraction of [A3] (mass%)]), and the molecular weight of the non-conjugated polyene [A3] ([molecular weight of [A3]]) satisfy the following formula (iii); 4.5 ≦ Mw × weight fraction of [A3] / 100 / molecular weight of [A3] ≦ 80 … Formula (iii) Requirement (6): The complex viscosity η at a frequency ω = 0.1 rad / s obtained by linear viscoelastic measurement (190 °C) using a rheometer * (ω=0.1) (Pa·sec), and the complex viscosity η at a frequency ω = 100 rad / s * (ω=100) (Pa·sec), and the ratio P (η * (ω=0.1) / η * (ω=100) ) and the intrinsic viscosity [η] of the copolymer (A) and the weight fraction of the above [A3] satisfy the following formula (iv); P / ([η] 2.9 ) ≦ weight fraction of [A3] × 6 … Formula (iv) Requirement (7): The complex viscosity η at a frequency ω = 0.01 rad / s obtained by linear viscoelastic measurement (190 °C) using a rheometer * (ω=0.01) (Pa·sec), and the complex viscosity η at a frequency ω = 10 rad / s * (ω=10)(Pa·sec) and the apparent iodine value derived from the non-conjugated polyene [A3] satisfy the following formula (v); Log{η * (ω=0.01)} / Log{η * (ω=10)} ≤ 0.0753 × {apparent iodine value derived from non-conjugated polyene [A3]} + 1.42 … Formula (v) Requirement (8): The glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) is -65°C or lower. [4] A 2-mm-thick sheet test piece obtained by press-treating the composition under the conditions of 180°C for 10 minutes was immersed in toluene at 37°C for 72 hours for swelling in accordance with JIS K 6258 (2016), and the effective network chain density (crosslink density) ν calculated by the Flory-Rehner formula was 1.5 × 10 19 pieces / cm 3 or more and 30 × 10 19 pieces / cm 3 or less. The composition according to any one of [1] to [3] above. [5] For a dumbbell-shaped No. 3 test piece described in JIS K 6251 (2023) obtained from a 2-mm-thick sheet obtained by press-treating the composition under the conditions of 180°C for 10 minutes, in accordance with the method specified in Article 13 of JIS K 6251, when a tensile test was conducted under the conditions of a measurement temperature of 25°C and a tensile speed of 500 mm / min, the elongation at break (Eb) was 210% or more. The composition according to any one of [1] to [4] above. [6] The composition according to any one of [1] to [5] above, which is a composition for a fuel cell gasket. [7] A fuel cell gasket obtained by using the composition according to [6] above.

Examples

[0104] Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" represents "parts by mass".

[0105] [Structure and physical properties of the copolymer] The structures and physical properties of each copolymer were measured according to the following description. (1) Content ratio (mol%), weight fraction (mass%), and molar ratio of structural units The content ratio (mol%) and weight fraction (mass%) of each structural unit in the copolymer, as well as the molar ratio of each structural unit, 13 were determined from the measurement values by C-NMR. The measurement values were obtained by using an ECX400P type nuclear magnetic resonance apparatus (manufactured by JEOL Ltd.) at a measurement temperature of 120 °C, a measurement solvent of orthodichlorobenzene / deuterated benzene = 4 / 1, and an integration number of 8000 times for the 13 C-NMR spectrum of the copolymer.

[0106] (2) Branching number BrNo The branching number BrNo of the copolymer was calculated by a structural analysis method from the absolute molecular weight distribution and the intrinsic viscosity obtained by using a 3D-high temperature GPC apparatus (PL-GPC220 type, manufactured by Polymer Laboratories). The main measurement conditions are as follows. The dn / dc value required for the determination of the absolute molecular weight was calculated for each sample from the dn / dc value of standard polystyrene (molecular weight 190,000) of 0.053 and the response intensity of the differential refractometer per unit injection mass. · Detector: Differential refractometer / built-in GPC apparatus 2-angle light scattering photometer PD2040 type (manufactured by Precison Detectors) Bridge type viscometer PL-BV400 type (manufactured by Polymer Laboratories) · Column: TSKgel GMH HR -H(S)HT × 2 pieces + TSKgel GMH HR -M(S) × 1 piece (each with an inner diameter of 7.8 mmφ and a length of 300 mm, manufactured by Tosoh Corporation) · Column temperature: 140 °C · Mobile phase: 1,2,4-trichlorobenzene (containing 0.025% BHT) · Injection volume: 0.5 mL · Sample concentration: ca 1.0 mg / mL · Sample filtration: Filtered through a sintered filter with a pore diameter of 1.0 μm

[0107] From the relationship between the intrinsic viscosity obtained from the viscometer and the absolute molecular weight obtained from the light scattering photometer, the long-chain branching parameter g' for each eluted component i was calculated from the following formula (v-1).

[0108]

Equation

[0109] Here, [η]=KM v ; The relational expression of v = 0.725 was applied. This formula is called the Mark-Houwink-Sakurada formula. K indicates the solvent constant. M indicates the average molecular weight. Each average value as g' was calculated from the following formulas (v-2), (v-3) and (v-4), respectively. The Trendline assuming only short-chain branches was determined for each sample.

[0110]

Equation

[0111] g' w Using g', the number of branch points BrNo per molecular chain was calculated. For the calculation of BrNo, the following formula (v-5) of Zimm-Stockmayer was used. g is the long-chain branching parameter obtained from the radius of gyration Rg, and the following simple correlation is made between g and g' obtained from the intrinsic viscosity. g = g' (1 / ε) (ε (structure factor) = 0.5 to 1.5) As ε in the above formula, various values have been proposed according to the shape of the molecule. Here, the calculation was performed assuming ε = 1 (that is, g' = g).

[0112]

Equation

[0113] (3) Intrinsic viscosity [η] The intrinsic viscosity [η] (dl / g) of the copolymer was measured using a fully automatic intrinsic viscometer manufactured by Rigo Co., Ltd. at a temperature of 135° C. and in decalin as a measurement solvent.

[0114] (4) Weight average molecular weight (Mw) The weight average molecular weight (Mw) of the copolymer was determined using a 3D-high temperature GPC apparatus (PL-GPC220, manufactured by Polymer Laboratories) under the same measurement conditions as those for "(2) Number of branch points BrNo" above.

[0115] (5) Mooney viscosity The Mooney viscosity ML(1+4)100°C of the copolymer was measured using a Mooney viscometer (Shimadzu Corporation, SMV-301 model) in accordance with JIS K 6300-1 (2013).

[0116] (6) Complex viscosity η * and P value The rheometer used was the Ares viscoelasticity measuring device (manufactured by Rheometric Scientific), and the complex viscosity η at a frequency of ω = 0.01 rad / s was measured under the conditions of 190°C and 1.0% strain. * (ω=0.01) , complex viscosity η at frequency ω=0.1rad / s * (ω=0.1) , complex viscosity η at frequency ω=10rad / s * (ω=10) , and the complex viscosity η at frequency ω=100rad / s * (ω=100) (All units are Pa sec) were measured. From the results, η * (ω=0.1) and η * (ω=100) The ratio of complex viscosity to * The P-value (η * (ω=0.1) / η * (ω=100) ) was calculated.

[0117] (7) Glass transition temperature (Tg) The glass transition temperature (Tg) of the copolymer was determined by DSC measurement under the following conditions. Using a differential scanning calorimeter (RDC220, manufactured by SII), a sample of approximately 10 mg was heated from 30 °C to 200 °C at a heating rate of 50 °C / min under a nitrogen atmosphere and held at that temperature for 10 minutes. It was then cooled to -100 °C at a cooling rate of 10 °C / min, held at that temperature for 5 minutes, and then heated to 200 °C at a heating rate of 10 °C / min.

[0118] The glass transition temperature (Tg) is detected when the DSC curve bends due to the change in specific heat and the baseline shifts parallel during the second heating. The temperature at the intersection of the tangent line of the baseline below this bend and the tangent line at the point where the slope is maximum in the bent part was defined as the glass transition temperature (Tg).

[0119] [Production Example 1] Using a 300 L polymerization reactor equipped with a stirring blade, the polymerization reaction of ethylene, 1-butene, and 5-vinyl-2-norbornene (VNB) was continuously carried out at 95 °C.

[0120] Using hexane (feed amount: 30.5 L / h) as the polymerization solvent, each component was continuously fed into the polymerization reactor so that the feed amount of ethylene was 5.3 kg / h, the feed amount of 1-butene was 21.5 kg / h, the feed amount of VNB was 566 g / h, and the feed amount of hydrogen was 10 NL / h.

[0121] While maintaining the polymerization pressure at 1.6 MPaG and the polymerization temperature at 95 °C, the feed amount of di(p-tolyl)methylene(cyclopentadienyl)(octamethyl octahydrodibenzofluorenyl)zirconium dichloride as the main catalyst was 0.00903 mmol / h, the feed amount of (C 6 H 5 ) 3 CB(C 6 F 5 ) 4 as the cocatalyst was 0.045 mmol / h, and the feed amount of triisobutylaluminum (TIBA) as the organoaluminum compound was 30 mmol / h, and each component was continuously fed into the polymerization reactor.

[0122] In this way, a solution containing 20% by mass of an ethylene·1-butene·VNB copolymer formed from ethylene, 1-butene, and VNB was obtained. A small amount of methanol was added to the polymerization reaction solution withdrawn from the lower part of the polymerization reactor to terminate the polymerization reaction. After separating the ethylene·1-butene·VNB copolymer from the solvent by steam stripping treatment, it was dried under reduced pressure at 80°C for one day and night.

[0123] By the above operations, an ethylene·1-butene·VNB copolymer (A-1) was obtained at a rate of 8.5 kg per hour. The structure and physical properties of the obtained copolymer (A-1) were measured by the methods described above. The results are shown in Table 1.

[0124] [Production Example 2] According to the description of [Synthesis Example C1] in International Publication No. 2015 / 122415, an ethylene·1-butene·5-ethylidene-2-norbornene (ENB) copolymer (cA-1) was obtained. The structure and physical properties of the obtained copolymer (cA-1) were measured by the methods described above. The results are shown in Table 1.

[0125]

Table 1

[0126] [Example 1] Using a MIXTRON BB MIXER (manufactured by Kobe Steel, Ltd., model BB-4, volume 2.95 L, rotor 4WH), 100 parts of an ethylene·1-butene·VNB copolymer (A-1) and 55 parts of Asahi #60UG (manufactured by Asahi Carbon Co., Ltd., grade: FEF) as carbon black (B) were blended and then kneaded to obtain Blend 1. The kneading conditions were a rotor rotation speed of 50 rpm, a floating weight pressure of 3 kg / cm 2 , a kneading time of 5 minutes, and a kneading discharge temperature of 150°C.

[0127] Next, after confirming that the temperature of Formulation 1 reached 40°C, using a 6-inch roll, 4.1 parts of a masterbatch (trade name: DCP-40C, a product containing 40% by mass of dicumyl peroxide (DCP), manufactured by Kayaku Nurion Co., Ltd.) as an organic peroxide (C) containing product was added to Formulation 1 and kneaded to obtain Formulation 2. The kneading conditions were: roll temperature of front roll / rear roll = 50°C / 50°C, roll peripheral speed of front roll / rear roll = 18 rpm / 15 rpm, roll gap of 3 mm, and the kneaded product was discharged after a kneading time of 5 minutes.

[0128] [Comparative Examples 1-2] It was carried out in the same manner as in Example 1 except that the compounding composition was changed as shown in Table 2.

[0129] [Example 2] Using a MIXTRON BB MIXER (manufactured by Kobe Steel, Ltd., model BB-4, volume 2.95 L, rotor 4WH), 100 parts of ethylene·1-butene·VNB copolymer (A-1), 5 parts of active zinc white (trade name: META-Z 102, manufactured by Inoue Lime Industry Co., Ltd.) as a crosslinking aid, 1 part of stearic acid (manufactured by NOF Corporation, powder stearic acid Sakura) as a processing aid, and 55 parts of Asahi #60UG (manufactured by Asahi Carbon Co., Ltd., grade: FEF) as carbon black (B) were compounded and then kneaded to obtain Formulation 1. The kneading conditions were: rotor rotation speed of 50 rpm, floating weight pressure of 3 kg / cm 2 , kneading time of 5 minutes, and kneading discharge temperature of 150°C.

[0130] Next, after confirming that the temperature of Formulation 1 reached 40°C, using a 6-inch roll, 3.4 parts of a masterbatch (trade name: DCP-40C, a product containing 40% by mass of dicumyl peroxide (DCP), manufactured by Kayaku Nurion Co., Ltd.) as an organic peroxide (C) containing product was added to Formulation 1 and kneaded to obtain Formulation 2. The kneading conditions were: roll temperature of front roll / rear roll = 50°C / 50°C, roll peripheral speed of front roll / rear roll = 18 rpm / 15 rpm, roll gap of 3 mm, and the kneaded product was discharged after a kneading time of 5 minutes.

[0131] [Example 3 and Comparative Example 3] The procedure was the same as in Example 2 except that the compounding composition was changed as described in Table 2.

[0132] [Evaluation of Unvulcanized Rubber Properties] <Vulcanization (Curing) Properties> Using an MDR2000 (manufactured by ALPHA TECHNOLOGIES) as a vulcanization measuring device, the vulcanization rate tc90 of the measurement sample (compound 2) was measured as follows. The torque change was measured under conditions of a constant temperature and a constant shear rate. The difference S'max - S'min between the maximum torque value S'max (dNm) and the minimum torque value S'min (dNm) was determined. When the minimum torque value S'min was taken as 0% and the maximum torque value S'max was taken as 100%, the time tc90 (min) when the torque of the measurement sample reached 90% was determined. The measurement conditions were a temperature of 180 °C and a time of 15 minutes. The smaller tc90 is, the faster the vulcanization rate of the above measurement sample can be judged.

[0133] [Evaluation of Vulcanizate (Cured Product) Physical Properties] For compound 2, a crosslinking treatment was carried out at 180 °C for 10 minutes using a press molding machine to produce a sheet (vulcanizate) with a thickness of 2 mm. For the obtained sheet, a hardness test, a tensile test, a TR test, and a measurement of the effective network chain density were carried out by the following methods.

[0134] <Hardness Test> The hardness (Durometer-A (Shore-A)) of the above sheet was measured in accordance with the description in Section 7, "Hardness Test" of "Physical Test Methods for Thermosetting Polyurethane Elastomer Moldings" in JIS K 7312 (1996) and the description of Test Type A in Section 6, "Durometer Hardness Test" of JIS K 6253 (2006), "Vulcanized Rubber and Thermoplastic Rubber - Method for Determining Hardness".

[0135] <Tensile Test> The modulus, tensile strength at break, and elongation at break of the above sheet were measured by the following method. The above sheet was punched out to produce dumbbell-shaped No. 3 test pieces described in JIS K 6251 (2023). Using this test piece, a tensile test was conducted according to the method specified in Article 13 of JIS K 6251 under the conditions of a measurement temperature of 25°C and a tensile speed of 500 mm / min, and the tensile stress (100% modulus (M100)), tensile strength at break (TSb), and elongation at break (Eb) when the elongation rate was 100% were measured.

[0136] For the above sheet, a TR test was conducted in accordance with "Vulcanized Rubber and Thermoplastic Rubber - Methods for Determining Low-Temperature Properties - Part 4: Low-Temperature Elastic Recovery Test (TR Test)" in JIS K 6261-4 (2017) to measure the cold resistance of the above sheet. In the TR test, a sheet stretched by 50% was frozen, and the temperature was continuously increased to measure the recoverability of the stretched sheet. The temperature at which the length of the sheet shrinks (recovers) by 10% due to the temperature increase (the temperature at which the shrinkage rate becomes 10%) is denoted as TR10. The lower the TR10 (unit: °C), the better the cold resistance of the above sheet can be judged.

[0137] <Effective network chain density> The above sheet was cut into a size of 20 mm × 20 mm × 2 mm to produce test pieces. In accordance with JIS K 6258 (2016), the test pieces were immersed in toluene at 37°C for 72 hours to swell, and the effective network chain density (crosslink density) was calculated using the following formula of Flory-Rehner.

[0138]

Equation

[0139] In the above formula, ν (pieces / cm 3 ) is the effective network chain density (crosslink density), which is the number of effective network chains in 1 cm 3 of pure rubber, V R is the volume fraction of pure rubber in the swollen crosslinked rubber, and V 0is the molecular volume of the solvent, μ is the interaction constant between the rubber and the solvent = 0.49, and A is Avogadro's number.

[0140] <Compression set (CS) test> For Compound 2, using a press molding machine with a cylindrical mold set, molding and cross-linking treatment were carried out at 180 °C for 13 minutes to prepare a straight cylindrical test piece (cross-linked product) with a thickness of 12.7 mm and a diameter of 29 mm. Using the obtained test pieces, in accordance with JIS K 6262 (2013), the compression set (CS) after treatment at 150 °C for 72 hours, 23 °C for 22 hours, -40 °C for 22 hours, and -50 °C for 22 hours was measured respectively.

[0141]

Table 2

[0142] From the above results in Table 2, it can be seen that by using a composition containing the ethylene·1-butene·VNB copolymer (A-1), a molded article with excellent TR10 (no decrease in TR10 can be observed even when the content of the organic peroxide is reduced) can be formed.

Claims

1. A composition comprising: The composition comprises: An ethylene-α-olefin-non-conjugated polyene copolymer (A); Carbon black (B); An organic peroxide (C); And contains: The copolymer (A) has structural units derived from ethylene [A1], structural units derived from an α-olefin [A2] having 4 to 20 carbon atoms, and structural units derived from a non-conjugated polyene [A3] containing two or more partial structures selected from the group consisting of the following formulas (I) and (II) in one molecule, and satisfies the following requirements (1) to (4). The structural units derived from the α-olefin [A2] having 4 to 20 carbon atoms include structural units derived from 1-butene. The structural units derived from the non-conjugated polyene [A3] include structural units derived from 5-vinyl-2-norbornene. In the composition, the content of the carbon black (B) is 5 to 150 parts by mass and the content of the organic peroxide (C) is 0.01 part by mass or more and less than 2.0 parts by mass with respect to 100 parts by mass of the copolymer (A). Composition: 【Chemical 1】 Requirement (1): The molar ratio ([A1] / [A2]) of the content of the structural units derived from ethylene [A1] to the content of the structural units derived from the α-olefin [A2] having 4 to 20 carbon atoms is 40 / 60 to 90 / 10. Requirement (2): The content ratio of the structural units derived from the non-conjugated polyene [A3] is 0.1 to 6.0 mol% when the total content of the structural units derived from [A1], the structural units derived from [A2], and the structural units derived from [A3] is 100 mol%. Requirement (3): The B value represented by the following formula (i) is 1.20 or more. B value = ([EX] + 2[Y]) / [2 × [E] × ([X] + [Y])]... Formula (i) [In formula (i), [E] represents the mole fraction of the structural units derived from ethylene [A1], [X] represents the mole fraction of the structural units derived from the α-olefin [A2] having 4 to 20 carbon atoms, [Y] represents the mole fraction of the structural units derived from the non-conjugated polyene [A3], and [EX] represents the ethylene [A1]-α-olefin [A2] having 4 to 20 carbon atoms dyad chain fraction.] Requirement (4): The number of branch points BrNo per molecular chain obtained using 3D-gel permeation chromatography (GPC) satisfies the following formula (ii). BrNo ≥ 0.5... Formula (ii)

2. The composition according to claim 1, wherein for a sheet-like test piece with a thickness of 2 mm obtained by pressing the composition under the conditions of 180 °C for 10 minutes, the TR10 measured in accordance with the TR test of JIS K 6261-4 (2017) is -60 °C or lower.

3. The composition according to claim 1, wherein the copolymer (A) satisfies one or more of the following requirements (5) to (8): Requirement (5): The weight average molecular weight (Mw) of the copolymer (A), the weight fraction of the structural unit derived from the non-conjugated polyene [A3] (weight fraction of [A3] (mass%)), and the molecular weight of the non-conjugated polyene [A3] (molecular weight of [A3]) satisfy the following formula (iii); 4.5 ≤ Mw × weight fraction of [A3] / 100 / molecular weight of [A3] ≤ 80 …Formula (iii) Requirement (6): The ratio P(η0.1 rad / s / η100 rad / s) of the complex viscosity η (Pa·sec) at a frequency ω = 0.1 rad / s and the complex viscosity η (Pa·sec) at a frequency ω = 100 rad / s, obtained by linear viscoelastic measurement (at 190 °C) using a rheometer, the intrinsic viscosity [η] of the copolymer (A), and the weight fraction of [A3] satisfy the following formula (iv); * (ω=0.1) (Pa·sec), and the ratio P(η * (ω=100) / η * (ω=0.1) ) of the copolymer (A) and the intrinsic viscosity [η] of the copolymer (A) and the weight fraction of [A3] satisfy the following formula (iv); * (ω=100) ) and the intrinsic viscosity [η] of the copolymer (A), and the weight fraction of [A3] satisfy the following formula (iv); P / ([η] 2.9 ) ≤ weight fraction of [A3] × 6 … Equation (iv) Requirement (7): The complex viscosity η at a frequency ω = 0.01 rad / s and the complex viscosity η at a frequency ω = 10 rad / s, obtained by linear viscoelastic measurement (at 190 °C) using a rheometer, and the apparent iodine value derived from the non-conjugated polyene [A3] satisfy the following formula (v); * (ω=0.01) (Pa·sec), and the complex viscosity η at a frequency ω = 10 rad / s * (ω=10) (Pa·sec), and the apparent iodine value derived from the non-conjugated polyene [A3] satisfy the following formula (v); Log{η * (ω=0.01)} / Log{η * (ω=10)} ≤ 0.0753 × {apparent iodine value derived from non-conjugated polyene [A3]} + 1.42... Equation (v) Requirement (8): The glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) is -65 °C or lower.

4. A sheet-shaped test piece with a thickness of 2 mm obtained by pressing the composition under the conditions of 180 °C for 10 minutes was immersed in toluene at 37 °C for 72 hours for swelling in accordance with JIS K 6258 (2016), and the effective network chain density (crosslinking density) ν calculated by the Flory-Rehner equation was 1.5 × 10 19 pieces / cm 3 or more and 30 × 10 19 pieces / cm 3 or less. The composition according to claim 1.

5. The composition according to claim 1, wherein for a dumbbell-shaped No. 3 test piece described in JIS K 6251 (2023) obtained from a sheet with a thickness of 2 mm obtained by pressing the composition under the conditions of 180 °C for 10 minutes, when a tensile test is performed in accordance with the method specified in Article 13 of JIS K 6251 under the conditions of a measurement temperature of 25 °C and a tensile speed of 500 mm / min, the elongation at break (Eb) is 210% or more.

6. The composition according to any one of claims 1 to 5, which is a composition for a fuel cell gasket.

7. A fuel cell gasket obtained by using the composition according to claim 6.

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