JP7702297B2 - Ethylene copolymer composition for fuel cell gasket, and fuel cell gasket made of said composition - Google Patents

Description

The present invention relates to an ethylene copolymer composition for fuel cell gaskets and its use.

Ethylene-α-olefin copolymer elastomers such as ethylene-propylene copolymers (EPM, EPR) and ethylene-propylene-diene copolymers (EPDM) have no unsaturated bonds in the main chain of their molecular structure, and therefore have superior heat aging resistance, weather resistance, and ozone resistance compared to general-purpose conjugated diene rubbers, and are widely used in applications such as automotive parts, electrical wire materials, electronic and electrical parts, construction and civil engineering materials, and industrial parts.

It is known that rubber moldings for sealing can be obtained using EPDM (for example, see Patent Document 1). Seal packings, which are rubber moldings for sealing, are used in a variety of applications, such as automobiles, industrial machinery, and electronic components. However, because automobiles and industrial machinery are also used in cold regions, seal packings are required to have low-temperature properties in addition to mechanical strength at room temperature.

Patent Document 2 proposes an ethylene copolymer composition for fuel cell gaskets that can form a seal packing that combines low-temperature properties and mechanical strength (strength and elongation), the composition containing an ethylene-α-olefin-non-conjugated polyene copolymer that includes a structural unit derived from ethylene [A] having a B value of 1.20 or more, a structural unit derived from an α-olefin [B] having 4 to 20 carbon atoms, and a structural unit derived from a non-conjugated polyene [C].

WO 2000/59962 JP 2017-075293 A

Fuel cell gaskets for fuel cell vehicles (FCVs) are rubber parts that prevent hydrogen, oxygen, and water leakage from within the FC stack, and require excellent durability in addition to low-temperature properties. There is also a demand for fuel cell gasket compositions that can improve fluidity and shorten vulcanization times to further increase productivity.

The object of the present invention is to obtain an ethylene copolymer composition for fuel cell gaskets that has improved fluidity, vulcanization speed, and durability, such as heat aging resistance.

The present invention relates to a polymerizable composition comprising an ethylene/α-olefin/non-conjugated polyene copolymer (S) having structural units derived from ethylene (A), an α-olefin (B) having 3 to 20 carbon atoms, and a non-conjugated polyene (C) containing in the molecule two or more partial structures selected from the group consisting of the following general formulas (I) and (II), and satisfying the following requirements (i) to (vi):
The present invention relates to an ethylene copolymer composition for a fuel cell gasket, characterized in that it contains 0 to 80 parts by mass of an ethylene-α-olefin-non-conjugated polyene copolymer (A) having 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], and satisfying the following requirements (1) to (3) (wherein the total of the copolymer (S) and the copolymer (A) is 100 parts by mass).).

[Requirements for ethylene-α-olefin-non-conjugated polyene copolymer (S)]
(i) the molar ratio of the structural units derived from ethylene (A) to the structural units derived from an α-olefin (B) [(A)/(B)] is 40/60 to 99.9/0.1;
(ii) the mass fraction of the constitutional unit derived from the non-conjugated polyene (C) is 0.07% by mass to 10% by mass in 100% by mass of the copolymer (S);
(iii) the weight average molecular weight (Mw) of the copolymer (S), the weight fraction of the constitutional unit derived from the non-conjugated polyene (C) (weight fraction (wt%) of (C)), and the molecular weight of the non-conjugated polyene (C) (molecular weight of (C)) satisfy the following formula (1);
4.5≦Mw×mass fraction of (C)/100/molecular weight of (C)≦40...Equation (1)
(iv) the ratio P(η*(ω=0.1)/η*(ω=100)) of the complex viscosity η*(ω=0.1) (Pa sec) at a frequency ω=0.1 rad/s to the complex viscosity η*(ω=100) (Pa sec) at a frequency ω=100 rad/s, which are obtained by linear viscoelasticity measurement (190° C.) using a rheometer, the intrinsic viscosity [η], and the mass fraction of the constituent unit derived from the non-conjugated polyene (C) (mass fraction of (C)) satisfy the following formula (2);
P/([η] ^2.9 )≦mass fraction of (C)×6 (2)
(v) the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (molecular weight distribution; Mw/Mn) measured by gel permeation chromatography (GPC) is in the range of 4 to 80;
(vi) The number average molecular weight (Mn) is 30,000 or less.

[Requirements for the ethylene/α-olefin/non-conjugated polyene copolymer (A)]
(1) the molar ratio [[A1]/[A2]] of the structural unit derived from ethylene [A1] to the structural unit derived from an α-olefin [A2] having 4 to 20 carbon atoms is 40/60 to 90/10;
(2) the content of the structural unit derived from the non-conjugated polyene [A3] is 0.1 to 6.0 mol % relative to 100 mol % of the total of the structural units derived from [A1], [A2] and [A3];
(3) The B value represented by the following formula (i) is 1.20 or more.
B value = ([EX]+2[Y])/[2×[E]×([X]+[Y])]...(i)
[Here, [E], [X] and [Y] respectively represent the molar fractions of structural units derived from ethylene [A1], an α-olefin having 4 to 20 carbon atoms [A2] and a non-conjugated polyene [A3], and [EX] represents the ethylene [A1]-α-olefin having 4 to 20 carbon atoms [A2] dyad chain fraction.]

The ethylene copolymer composition for fuel cell gaskets of the present invention has a fast crosslinking rate (vulcanization rate) and good fluidity, and the fuel cell gasket obtained by crosslinking the copolymer composition has excellent compression set and heat aging resistance, which can improve the productivity when manufacturing fuel cell gaskets and the durability (long life) of the product.

<Ethylene-α-olefin-non-conjugated polyene copolymer (S)>
The ethylene-α-olefin-non-conjugated polyene copolymer (S) (hereinafter sometimes abbreviated as "copolymer (S)"), which is the main component of the ethylene copolymer composition for a fuel cell gasket of the present invention, is an ethylene-α-olefin-non-conjugated polyene copolymer having constitutional units derived from ethylene (A), an α-olefin (B) having 3 to 20 carbon atoms, and a non-conjugated polyene (C) containing in the molecule a total of two or more partial structures selected from the group consisting of the following general formulas (I) and (II), and satisfying the following requirements (i) to (vi):

(i) the molar ratio of the structural units derived from ethylene (A) to the structural units derived from an α-olefin (B) [(A)/(B)] is 40/60 to 99.9/0.1;
(ii) the mass fraction of the constitutional unit derived from the non-conjugated polyene (C) is 0.07% by mass to 10% by mass in 100% by mass of the copolymer (S);
(iii) the weight average molecular weight (Mw) of the copolymer (S), the weight fraction of the constitutional unit derived from the non-conjugated polyene (C) (weight fraction (wt%) of (C)), and the molecular weight of the non-conjugated polyene (C) (molecular weight of (C)) satisfy the following formula (1);
4.5≦Mw×mass fraction of (C)/100/molecular weight of (C)≦40...Equation (1)
(iv) the ratio P(η*(ω=0.1)/η*(ω=100)) of the complex viscosity η*(ω=0.1) (Pa sec) at a frequency ω=0.1 rad/s to the complex viscosity η*(ω=100) (Pa sec) at a frequency ω=100 rad/s, which are obtained by linear viscoelasticity measurement (190° C.) using a rheometer, the intrinsic viscosity [η], and the mass fraction of the constituent unit derived from the non-conjugated polyene (C) (mass fraction of (C)) satisfy the following formula (2);
P/([η] ^2.9 )≦mass fraction of (C)×6 (2)
(v) the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (molecular weight distribution; Mw/Mn) measured by gel permeation chromatography (GPC) is in the range of 4 to 80;
(vi) The number average molecular weight (Mn) is 30,000 or less.

The copolymer (S) according to the present invention may have, in addition to the structural units derived from the above (A), (B), and (C), a structural unit derived from a non-conjugated polyene (D) containing only one partial structure selected from the group consisting of the above general formulas (I) and (II) in the molecule.

Examples of α-olefins (B) having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-eicosene. Among these, α-olefins having 3 to 8 carbon atoms such as propylene, 1-butene, 1-hexene, and 1-octene are preferred, and propylene is particularly preferred. Such α-olefins are preferred because the raw material costs are relatively low, the resulting ethylene-α-olefin-non-conjugated polyene copolymers exhibit excellent mechanical properties, and molded articles having rubber elasticity can be obtained. These α-olefins may be used alone or in combination.

The copolymer (S) according to the present invention contains structural units derived from at least one type of α-olefin (B) having 3 to 20 carbon atoms, and may contain structural units derived from two or more types of α-olefins (B) having 3 to 20 carbon atoms.

Examples of the non-conjugated polyene (C) containing two or more partial structures selected from the group consisting of the above general formulas (I) and (II) in the molecule in total include 5-vinyl-2-norbornene (VNB), norbornadiene, 1,4-hexadiene, dicyclopentadiene, etc. Among these, it is preferable that the non-conjugated polyene (C) contains VNB, and it is more preferable that the non-conjugated polyene (C) is VNB, since it is highly available, has good hydrosilyl crosslinking, and is likely to improve the heat resistance of the polymer composition. The non-conjugated polyene (C) may be used alone or in combination of two or more kinds.

The copolymer (S) according to the present invention may contain, in addition to the structural units derived from ethylene (A), the α-olefin (B) having 3 to 20 carbon atoms, and the non-conjugated polyene (C), a structural unit derived from a non-conjugated polyene (D) containing only one partial structure selected from the group consisting of the general formulas (I) and (II) in the molecule.

Examples of such non-conjugated polyenes (D) include 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, Examples of such compounds include 5-(1,2-dimethyl-5-hexenyl)-2-norbornene, 5-(1,2-dimethyl-5-hexenyl)-2-norbornene, 5-(1,2-ethyl-5-hexenyl)-2-norbornene, and 5-(1,2,3-trimethyl-4-pentenyl)-2-norbornene. Among these, ENB is preferred because it is easily available, the crosslinking rate during hydrosilyl crosslinking is easily controlled, and good mechanical properties are easily obtained. The non-conjugated polyene (D) may be used alone or in combination of two or more.

When the copolymer (S) according to the present invention contains a structural unit derived from a non-conjugated polyene (D) containing only one partial structure selected from the group consisting of the general formulas (I) and (II) in the molecule, the proportion is not particularly limited as long as it does not impair the object of the present invention, but is usually contained in a mass fraction of about 0 to 20 mass%, preferably 0 to 8 mass%, and more preferably 0.01 to 8 mass% (where the sum of the weight fractions of (A), (B), (C), and (D) is taken as 100 mass%).

<Requirement (i)>
Requirement (i) specifies that the molar ratio of ethylene/α-olefin in the copolymer (S) according to the present invention satisfies 40/60 to 99.9/0.1, and this molar ratio preferably satisfies 50/50 to 90/10, more preferably 55/45 to 85/15, and even more preferably 55/45 to 78/22. A fuel cell gasket obtained by crosslinking an ethylene copolymer composition for a fuel cell gasket containing the ethylene/α-olefin/non-conjugated polyene copolymer (S) according to the present invention exhibits excellent rubber elasticity and is excellent in mechanical strength and heat aging resistance, which is preferable.

The ethylene amount (content of constituent units derived from ethylene (A)) and the α-olefin amount (content of constituent units derived from α-olefin (B)) in the ethylene-α-olefin-non-conjugated polyene copolymer (S) can be determined by ¹³ C-NMR.

<Requirement (ii)>
Requirement (ii) specifies that in the ethylene-α-olefin-non-conjugated polyene copolymer (S) of the present invention, the mass fraction of the structural units derived from the non-conjugated polyene (C) is in the range of 0.07 to 10 mass% in 100 mass% of the ethylene-α-olefin-non-conjugated polyene copolymer (S) (i.e., in the total mass fraction of all structural units, 100 mass%). The mass fraction of the structural units derived from the non-conjugated polyene (C) is preferably 0.1 to 8.0 mass%, more preferably 0.5 to 5.0 mass%.

When the copolymer (S) according to the present invention satisfies the requirement (ii), the ethylene copolymer composition for a fuel cell gasket according to the present invention has good fluidity and vulcanization speed, and the resulting fuel cell gasket exhibits excellent rubber elasticity and is excellent in mechanical strength and heat aging resistance, which is preferable.
The amount of non-conjugated polyene (C) in the copolymer (S) (the content of structural units derived from non-conjugated polyene (C)) can be determined by ¹³ C-NMR.

<Requirement (iii)>
The requirement (iii) specifies that in the copolymer (S) according to the present invention, the weight average molecular weight (Mw) of the ethylene-α-olefin-non-conjugated polyene copolymer, the mass fraction of the constituent unit derived from the non-conjugated polyene (C) in the copolymer (mass fraction of (C): mass %), and the molecular weight of the non-conjugated polyene (C) (molecular weight of (C)) satisfy the following relational formula (1).
4.5≦Mw×mass fraction of (C)/100/molecular weight of (C)≦40...Equation (1)

When the copolymer (S) according to the present invention satisfies the requirement (iii), the content of structural units derived from the non-conjugated polyene (C) such as VNB is appropriate, and when a fuel cell gasket is produced using the ethylene copolymer composition for a fuel cell gasket according to the present invention, the crosslinking speed is excellent and the fuel cell gasket after crosslinking exhibits excellent mechanical properties, which is preferable.

It is more preferable that the copolymer (S) according to the present invention satisfies the following relational formula (1').
4.5≦Mw×mass fraction of (C)/100/molecular weight of (C)≦35...formula (1′)
The weight average molecular weight (Mw) of the copolymer (S) can be determined as a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

When the "Mw x mass fraction of (C)/100/molecular weight of (C)" of the copolymer (S) according to the present invention satisfies the above formula (1) or (1'), the degree of crosslinking is appropriate, and by using this, a fuel cell gasket having a good balance of mechanical properties and heat aging resistance can be manufactured. If the "Mw x mass fraction of (C)/100/molecular weight of (C)" is too low, the crosslinking may be insufficient, resulting in a slow crosslinking rate, and if it is too high, excessive crosslinking may occur, resulting in deterioration of the mechanical properties of the resulting fuel cell gasket.

<Requirement (iv)>
Requirement (iv) specifies that the ratio P(η*(ω=0.1)/η*(ω=100)) of the complex viscosity η ^* ₍ ω _=0.1) (Pa sec) at a frequency ω=0.1 rad/s to the complex viscosity η ^* ₍ ω ₌₁₀₀₎ (Pa sec) at a frequency ω=100 rad/s, which are obtained by linear viscoelastic measurement _{( 190 °} C.) using a rheometer, the intrinsic viscosity [ ^{η ]} , and the mass fraction of the constitutional unit derived from the non-conjugated polyene (C) (mass fraction of (C): mass %) of the copolymer _(S ) according to the present invention satisfy the following formula (2):
P/([η] ^2.9 )≦mass fraction of (C)×6 (2)

Here, the ratio P(η ^* ₍ ω _{=0.1)/η*(ω=100)) of the complex viscosity η*( ω=0.1)} ^at _a frequency ω ₌ 0.1 rad/s to the complex viscosity ^{η* (} _{ω =100)} at a frequency ω=100 rad/s represents the frequency dependency of the viscosity, and P/([η] ^2.9 ) on the left side of formula (2) tends to show a high value when there are many long chain branches, although it is affected by short chain branches and molecular weight. Generally, in an ethylene-α-olefin-non-conjugated polyene copolymer, the more structural units derived from non-conjugated polyenes are contained, the more long chain branches are contained. However, the copolymer (S) according to the present invention has less long chain branches than the conventionally known ethylene-α-olefin-non-conjugated polyene copolymers, and is therefore considered to be able to satisfy the above formula (2). In the present invention, the P value is the ratio (η* ratio) of the complex viscosity at 0.1 rad/s and the complex viscosity at 100 rad/s, which are measured at 190°C, a strain of 1.0%, and various frequencies using a viscoelasticity measuring device Ares (manufactured by Rheometric Scientific).

The copolymer (S) according to the present invention preferably satisfies the following formula (2').
P/([η] ^2.9 )≦mass fraction of (C)×5.7...Equation (2')
The intrinsic viscosity [η] means a value measured in decalin at 135° C.

<Requirement (v)>
The copolymer (S) according to the present invention has a ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (molecular weight distribution; Mw/Mn) measured by gel permeation chromatography (GPC) in the range of 4 to 80, preferably 3 to 70.

<Requirement (vi)>
The copolymer (S) according to the present invention has a number average molecular weight (Mn) of 30,000 or less, preferably in the range of 200 to 28,000.

The copolymer (S) according to the present invention preferably has an intrinsic viscosity [η] of 0.1 to 5 dL/g, more preferably 0.5 to 5.0 dL/g, and even more preferably 0.7 to 4.0 dL/g.

<Production of Ethylene-α-Olefin-Non-Conjugated Polyene Copolymer (S)>
The ethylene-α-olefin-non-conjugated polyene copolymer (S) according to the present invention is a copolymer obtained by copolymerizing monomers consisting of ethylene (A), an α-olefin (B) having 3 to 20 carbon atoms, a non-conjugated polyene (C) containing in the molecule a total of two or more partial structures selected from the group consisting of the general formulae (I) and (II), and, as necessary, a non-conjugated polyene (D) containing in the molecule only one partial structure selected from the group consisting of the general formulae (I) and (II).

The copolymer (S) according to the present invention may be prepared by any method as long as it satisfies the above requirements (i) and (ii), preferably (iii) to (v). However, it is preferable that the copolymer (S) is obtained by copolymerizing monomers in the presence of a metallocene compound, and more preferably, the copolymer (S) is obtained by copolymerizing monomers in the presence of a catalyst system containing a metallocene compound.

Specifically, the copolymer (S) according to the present invention can be produced, for example, by employing the method using a metallocene catalyst described in WO 2015/122495.

<Ethylene/α-olefin/non-conjugated polyene copolymer (A)>
The ethylene-α-olefin-non-conjugated polyene copolymer (A) (hereinafter, sometimes abbreviated as "copolymer (A)"), which is a minor component of the ethylene copolymer composition for a fuel cell gasket of the present invention, contains a structural unit derived from ethylene [A], a structural unit derived from at least one kind of α-olefin [B] having 4 to 20 carbon atoms, and a structural unit derived from at least one kind of non-conjugated polyene [C], and satisfies the following requirements (1) to (4).

<Requirement (1)>
the molar ratio [[A]/[B]] of the structural unit derived from ethylene [A] to the structural unit derived from an α-olefin [B] is 40/60 to 90/10;
<Requirement (2)>
the content of the structural unit derived from the non-conjugated polyene [C] is 0.1 to 6.0 mol % relative to 100 mol % of the total of the structural units [A], [B] and [C];
<Requirement (3)>
The B value represented by the following formula (i) is 1.20 or more.
B value = ([EX] + 2[Y]) / [2 x [E] x ([X] + [Y])]... (i)
[Here, [E], [X] and [Y] respectively represent the molar fractions of ethylene [A], α-olefin [B] having 4 to 20 carbon atoms, and non-conjugated polyene [C], and [EX] represents the ethylene [A]-α-olefin [B] having 4 to 20 carbon atoms dyad chain fraction.]

Examples of α-olefins [B] having 4 to 20 carbon atoms include 1-butene having 4 carbon atoms, which has a straight-chain structure without side chains, through 1-nonene having 9 carbon atoms and 1-decene having 10 carbon atoms, 1-nonadecene having 19 carbon atoms, 1-eicosene having 20 carbon atoms, and 4-methyl-1-pentene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene, etc., which have side chains.

These α-olefins [B] can be used alone or in combination of two or more. Among these, α-olefins having 4 to 10 carbon atoms are preferred, with 1-butene, 1-hexene, and 1-octene being particularly preferred, and 1-butene being particularly preferred.

Ethylene-propylene-non-conjugated polyene copolymers in which the α-olefin is propylene have insufficient rubber elasticity at low temperatures, so their applications may be limited. On the other hand, ethylene-α-olefin-non-conjugated polyene copolymers (A) have structural units derived from α-olefins [B] with 4 to 20 carbon atoms, and therefore have excellent rubber elasticity at low temperatures.

Specific examples of non-conjugated polyenes [C] include linear non-conjugated dienes such as 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, and 7-methyl-1,6-octadiene; cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, and 5-isopropylidene-2-norbornene. cyclic non-conjugated dienes such as norbornene and 6-chloromethyl-5-isopropenyl-2-norbornene; trienes such as 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,5-norbornadiene, 1,3,7-octatriene, 1,4,9-decatriene, 4,8-dimethyl-1,4,8-decatriene, and 4-ethylidene-8-methyl-1,7-nonadiene.

These non-conjugated polyenes [C] can be used alone or in combination of two or more kinds.
Among these, linear non-conjugated dienes such as 1,4-hexadiene, and cyclic non-conjugated dienes such as 5-ethylidene-2-norbornene, 5-ethylidene-2-norbornene, and 5-vinyl-2-norbornene are preferred, and among these, cyclic non-conjugated dienes are preferred, with 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene being particularly preferred.

Examples of the ethylene/α-olefin/non-conjugated polyene copolymer (A) according to the present invention include the following.
Ethylene/1-butene/1,4-hexadiene copolymer,
Ethylene/1-pentene/1,4-hexadiene copolymer,
Ethylene/1-hexene/1,4-hexadiene copolymer,
Ethylene/1-heptene/1,4-hexadiene copolymer,
Ethylene/1-octene/1,4-hexadiene copolymer,
ethylene/1-nonene/1,4-hexadiene copolymer,
Ethylene/1-decene/1,4-hexadiene copolymer,
Ethylene/1-butene/1-octene/1,4-hexadiene copolymer,
Ethylene/1-butene/5-ethylidene-2-norbornene copolymer,
Ethylene/1-pentene/5-ethylidene-2-norbornene copolymer,
Ethylene/1-hexene/5-ethylidene-2-norbornene copolymer,
Ethylene/1-heptene/5-ethylidene-2-norbornene copolymer,
Ethylene/1-octene/5-ethylidene-2-norbornene copolymer,
Ethylene/1-nonene/5-ethylidene-2-norbornene copolymer,
Ethylene/1-decene/5-ethylidene-2-norbornene copolymer,
Ethylene/1-butene/1-octene/5-ethylidene-2-norbornene copolymer,
Ethylene/1-butene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymer,
Ethylene/1-pentene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymer,
Ethylene/1-hexene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymer,
Ethylene/1-heptene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymer,
Ethylene/1-octene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymer,
Ethylene/1-nonene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymer,
Ethylene/1-decene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymer,
Ethylene/1-butene/1-octene/5-ethylidene-2-norbornene/5-vinyl-2-norbornene copolymer.

One or more types of ethylene-α-olefin-non-conjugated polyene copolymer (A) may be used as necessary.

<Requirement (1)>
The molar ratio [A]/[B] of the structural units derived from ethylene [A] to the structural units derived from α-olefin [B] is in the range of 40/60 to 90/10, preferably 40/60 to 80/20, more preferably 45/55 to 70/30, and particularly preferably 50/50 to 70/30.
When the molar ratio of the structural units derived from ethylene [A] to the structural units derived from α-olefin [B] is within the above range, an ethylene-based copolymer having an excellent balance between rubber elasticity at low temperatures and tensile strength at room temperature can be obtained.

<Requirement (2)>
The content of the structural unit derived from the non-conjugated polyene [C] is in the range of 0.1 to 6.0 mol %, preferably 0.1 to 4.0 mol %, and more preferably 0.5 to 3.0 mol %, relative to 100 mol % of the total of the structural units [A], [B] and [C].
When the structural unit derived from the non-conjugated polyene [C] is within the above range, an ethylene copolymer having sufficient crosslinkability and flexibility can be obtained.

<Requirement (3)>
The B value is 1.20 or more, preferably 1.20 to 1.80, and particularly preferably 1.22 to 1.40.
An ethylene copolymer having a B value of less than 1.20 has a large compression set at low temperatures, and there is a risk that an ethylene copolymer having an excellent balance between rubber elasticity at low temperatures and tensile strength at room temperature cannot be obtained.

The B value is an index showing the randomness of the copolymerization monomer sequence distribution in the copolymer, and [E], [X], [Y], and [EX] in the above formula (i) can be determined by measuring a ¹³ C-NMR spectrum based on the reports of J. C. Randall [Macromolecules, 15, 353 (1982)] and J. Ray [Macromolecules, 10, 773 (1977)].

The ethylene/α-olefin/non-conjugated polyene copolymer (A) according to the present invention preferably has a Mooney viscosity at 100° C. ML ₍₁₊₄₎ 100° C. in the range of 5 to 100, more preferably 10 to 90, and particularly preferably 10 to 70.

When the Mooney viscosity is within the above range, an ethylene-α-olefin-non-conjugated polyene copolymer (A) is obtained that exhibits good post-processing (ribbon handling properties) and has excellent rubber properties.

<<Method for producing ethylene/α-olefin/non-conjugated polyene copolymer (A)>>
The copolymer (A) according to the present invention can be obtained by the following production method.
Specifically, the polymerizable compound can be produced by copolymerizing ethylene, an α-olefin having 4 to 20 carbon atoms, and a non-conjugated polyene in the presence of an olefin polymerization catalyst containing (a) a transition metal compound represented by the following general formula [I] (hereinafter also referred to as a "bridged metallocene compound"), and (b) at least one compound selected from (b-1) an organometallic compound, (b-2) an organoaluminum oxy compound, and (b-3) a compound that reacts with the transition metal compound (a) to form an ion pair.

(In formula [I], Y is selected from a carbon atom, a silicon atom, a germanium atom, and a tin atom;
M is a titanium atom, a zirconium atom, or a hafnium atom;
R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are atoms or substituents selected from a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an aryl group, a substituted aryl group, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen atom and a halogen-containing group, and may be the same or different;
Adjacent substituents of R ¹ to R ⁶ may be bonded to each other to form a ring;
Q is selected from the group consisting of halogen atoms, hydrocarbon groups having 1 to 20 carbon atoms, anionic ligands, and neutral ligands capable of coordinating with lone electron pairs, and may be the same or different in combination;
n is an integer from 1 to 4,
j is an integer from 1 to 4.

<Bridged Metallocene Compound (a)>
The bridged metallocene compound (a) is represented by the above general formula [I]. Y, M, R ¹ to R ⁶ , Q and j in formula [I] will be explained below.

(Y, M, R ¹ to R ⁶ , Q, n and j)
Y is selected from a carbon atom, a silicon atom, a germanium atom and a tin atom, and is preferably a carbon atom.

M is a titanium atom, a zirconium atom or a hafnium atom, preferably a hafnium atom.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are atoms or substituents selected from a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an aryl group, a substituted aryl group, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen atom and a halogen-containing group, and may be the same or different. Adjacent substituents from R ¹ to R ⁶ may be bonded to each other to form a ring, or may not be bonded to each other.

Here, examples of the hydrocarbon group having 1 to 20 carbon atoms include an alkyl group having 1 to 20 carbon atoms, a cyclic saturated hydrocarbon group having 3 to 20 carbon atoms, a linear unsaturated hydrocarbon group having 2 to 20 carbon atoms, and a cyclic unsaturated hydrocarbon group having 3 to 20 carbon atoms. In addition, in cases where adjacent substituents ^R1 to ^R6 are bonded to each other to form a ring, examples include an alkylene group having 1 to 20 carbon atoms and an arylene group having 6 to 20 carbon atoms.

Examples of alkyl groups having 1 to 20 carbon atoms include linear saturated hydrocarbon groups such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decanyl, and branched saturated hydrocarbon groups such as isopropyl, isobutyl, s-butyl, t-butyl, t-amyl, neopentyl, 3-methylpentyl, 1,1-diethylpropyl, 1,1-dimethylbutyl, 1-methyl-1-propylbutyl, 1,1-dipropylbutyl, 1,1-dimethyl-2-methylpropyl, 1-methyl-1-isopropyl-2-methylpropyl, and cyclopropylmethyl. The number of carbon atoms in the alkyl group is preferably 1 to 6.

Examples of cyclic saturated hydrocarbon groups having 3 to 20 carbon atoms include cyclic saturated hydrocarbon groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, norbornenyl, 1-adamantyl, and 2-adamantyl, and groups in which the hydrogen atoms of cyclic saturated hydrocarbon groups are replaced with hydrocarbon groups having 1 to 17 carbon atoms such as 3-methylcyclopentyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 4-cyclohexylcyclohexyl, and 4-phenylcyclohexyl. The number of carbon atoms in the cyclic saturated hydrocarbon group is preferably 5 to 11.

Examples of linear unsaturated hydrocarbon groups having 2 to 20 carbon atoms include alkenyl groups such as ethenyl (vinyl), 1-propenyl, 2-propenyl (allyl), and 1-methylethenyl (isopropenyl), and alkynyl groups such as ethynyl, 1-propynyl, and 2-propynyl (propargyl). The number of carbon atoms in the linear unsaturated hydrocarbon group is preferably 2 to 4.

Examples of cyclic unsaturated hydrocarbon groups having 3 to 20 carbon atoms include cyclic unsaturated hydrocarbon groups such as cyclopentadienyl, norbornyl, phenyl, naphthyl, indenyl, azulenyl, phenanthryl, and anthracenyl; groups in which hydrogen atoms of cyclic unsaturated hydrocarbon groups are replaced with hydrocarbon groups having 1 to 15 carbon atoms, such as 3-methylphenyl (m-tolyl), 4-methylphenyl (p-tolyl), 4-ethylphenyl, 4-t-butylphenyl, 4-cyclohexylphenyl, biphenylyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, and 2,4,6-trimethylphenyl (mesityl); and groups in which hydrogen atoms of linear or branched saturated hydrocarbon groups are replaced with cyclic saturated or unsaturated hydrocarbon groups having 3 to 19 carbon atoms, such as benzyl and cumyl. The number of carbon atoms in the cyclic unsaturated hydrocarbon group is preferably 6 to 10.

Examples of alkylene groups having 1 to 20 carbon atoms include methylene, ethylene, dimethylmethylene (isopropylidene), ethylmethylene, 1-methylethylene, 2-methylethylene, 1,1-dimethylethylene, 1,2-dimethylethylene, and n-propylene. The number of carbon atoms in the alkylene group is preferably 1 to 6.

Examples of the arylene group having 6 to 20 carbon atoms include an o-phenylene group, an m-phenylene group, a p-phenylene group, a 4,4'-biphenylylene group, etc. The number of carbon atoms of the arylene group is preferably 6 to 12.

The aryl group partially overlaps with the examples of the cyclic unsaturated hydrocarbon group having 3 to 20 carbon atoms described above, but examples include substituents derived from aromatic compounds, such as phenyl, 1-naphthyl, 2-naphthyl, anthracenyl, phenanthrenyl, tetracenyl, chrysenyl, pyrenyl, indenyl, azulenyl, pyrrolyl, pyridyl, furanyl, and thiophenyl. As the aryl group, a phenyl group or a 2-naphthyl group is preferred.

Examples of the aromatic compounds include aromatic hydrocarbons and heterocyclic aromatic compounds such as benzene, naphthalene, anthracene, phenanthrene, tetracene, chrysene, pyrene, indene, azulene, pyrrole, pyridine, furan, and thiophene.

Substituted aryl groups partially overlap with the examples of the cyclic unsaturated hydrocarbon groups having 3 to 20 carbon atoms described above, but examples include groups in which one or more hydrogen atoms of the aryl group are substituted with a substituent selected from a hydrocarbon group having 1 to 20 carbon atoms, an aryl group, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen atom, and a halogen-containing group. Specific examples include a 3-methylphenyl group (m-tolyl group), a 4-methylphenyl group (p-tolyl group), a 3-ethylphenyl group, a 4-ethylphenyl group, a 3,4-dimethylphenyl group, a 3,5-dimethylphenyl group, a biphenylyl group, a 4-(trimethylsilyl)phenyl group, a 4-aminophenyl group, a Examples of the aryl group include a 4-(dimethylamino)phenyl group, a 4-(diethylamino)phenyl group, a 4-morpholinylphenyl group, a 4-methoxyphenyl group, a 4-ethoxyphenyl group, a 4-phenoxyphenyl group, a 3,4-dimethoxyphenyl group, a 3,5-dimethoxyphenyl group, a 3-methyl-4-methoxyphenyl group, a 3,5-dimethyl-4-methoxyphenyl group, a 3-(trifluoromethyl)phenyl group, a 4-(trifluoromethyl)phenyl group, a 3-chlorophenyl group, a 4-chlorophenyl group, a 3-fluorophenyl group, a 4-fluorophenyl group, a 5-methylnaphthyl group, and a 2-(6-methyl)pyridyl group. Examples of the substituted aryl group include the "electron-donating group-containing substituted aryl group" described later.

Examples of silicon-containing groups include alkylsilyl groups such as trimethylsilyl, triethylsilyl, t-butyldimethylsilyl, and triisopropylsilyl, which are hydrocarbon groups having 1 to 20 carbon atoms in which carbon atoms have been replaced with silicon atoms, arylsilyl groups such as dimethylphenylsilyl, methyldiphenylsilyl, and t-butyldiphenylsilyl, pentamethyldisilanyl, and trimethylsilylmethyl groups. The number of carbon atoms in the alkylsilyl group is preferably 1 to 10, and the number of carbon atoms in the arylsilyl group is preferably 6 to 18.

Examples of the nitrogen-containing group include an amino group, a nitro group, an N-morpholinyl group, and a dimethylamino group, a diethylamino group, a dimethylaminomethyl group, a cyano group, a pyrrolidinyl group, a piperidinyl group, a pyridinyl _group , and the like, which are groups in which the =CH- structural unit in the above-mentioned hydrocarbon group having 1 to 20 carbon atoms or silicon-containing group is replaced with a nitrogen atom, a group in which the _-CH2- structural unit is replaced with a nitrogen atom to which a hydrocarbon group having 1 to 20 carbon atoms is bonded, or a group in which the -CH3 structural unit is replaced with a nitrogen atom to which a hydrocarbon group having 1 to 20 carbon atoms is bonded or a nitrile group. As the nitrogen-containing group, a dimethylamino group or an N-morpholinyl group is preferred.

The oxygen-containing group includes a hydroxyl group, the above-mentioned hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group or a nitrogen-containing group in which the --CH ₂ -- structural unit is replaced with an oxygen atom or a carbonyl group, or --CH _Examples of the oxygen-containing group include a methoxy group, an ethoxy group, a t-butoxy group, a phenoxy group, a trimethylsiloxy group, a methoxyethoxy group, a hydroxymethyl group, a methoxymethyl group, an ethoxymethyl group, a t-butoxymethyl group, a 1-hydroxyethyl group, a 1-methoxyethyl group, a 1-ethoxyethyl group, a 2-hydroxyethyl group, a 2-methoxyethyl group, a 2-ethoxyethyl group, a n-2-oxabutylene group, a n-2-oxapentylene group, a n-3-oxapentylene group, an aldehyde group, an acetyl group, a propionyl group, a benzoyl group, a trimethylsilylcarbonyl group, a carbamoyl group, a methylaminocarbonyl group, a carboxy group, a methoxycarbonyl group, a carboxymethyl group, an ethoxycarboxymethyl group, a carbamoylmethyl group, a furanyl group, and a pyranyl group, each of which has three structural units replaced with an oxygen atom bonded to a hydrocarbon group having 1 to 20 carbon atoms. As the oxygen-containing group, a methoxy group is preferable.

Examples of halogen atoms include Group 17 elements such as fluorine, chlorine, bromine, and iodine.
Examples of the halogen-containing group include a trifluoromethyl group, a tribromomethyl group, a pentafluoroethyl group, a pentafluorophenyl group, and the like, which are groups in which a hydrogen atom in the above-mentioned hydrocarbon group having 1 to 20 carbon atoms, silicon-containing group, nitrogen-containing group, or oxygen-containing group is substituted with a halogen atom.

Q may be the same or different and selected from a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an anionic ligand, and a neutral ligand capable of coordinating with a lone electron pair.
Details of the halogen atom and the hydrocarbon group having 1 to 20 carbon atoms are as described above. When Q is a halogen atom, it is preferably a chlorine atom. When Q is a hydrocarbon group having 1 to 20 carbon atoms, it is preferable that the number of carbon atoms in the hydrocarbon group is 1 to 7.

Examples of anionic ligands include alkoxy groups such as methoxy, t-butoxy, and phenoxy groups, carboxylate groups such as acetate and benzoate, and sulfonate groups such as mesylate and tosylate.

Examples of neutral ligands that can be coordinated with lone electron pairs include organic phosphorus compounds such as trimethylphosphine, triethylphosphine, triphenylphosphine, and diphenylmethylphosphine, and ether compounds such as tetrahydrofuran, diethyl ether, dioxane, and 1,2-dimethoxyethane.

n is an integer from 1 to 4.
j is an integer of 1 to 4, preferably 2.
The above examples regarding formula [I] are similarly applied to the following description.

The 2,3,6,7-tetramethylfluorenyl group contained in the bridged metallocene compound (a) represented by the above general formula [I] has four substituents at the 2, 3, 6 and 7 positions, and therefore has a large electronic effect, which is presumed to produce a high molecular weight ethylene-α-olefin-non-conjugated polyene copolymer (A) with high polymerization activity. On the other hand, since non-conjugated polyenes are generally bulkier than α-olefins, it is presumed that the copolymerization performance of non-conjugated polyenes is improved if the polymerization catalyst that polymerizes them, particularly the vicinity of the central metal of the metallocene compound that serves as the polymerization active site, is not bulky. The four methyl groups contained in the 2,3,6,7-tetramethylfluorenyl group are not bulky compared to other hydrocarbon groups, and this is thought to contribute to the high non-conjugated polyene copolymerization performance. From the above, it is speculated that the bridged metallocene compound represented by the above general formula [I], which contains a 2,3,6,7-tetramethylfluorenyl group, achieves a high level of balance between a high molecular weight, high non-conjugated polyene copolymerization performance, and high polymerization activity of the resulting ethylene-α-olefin-non-conjugated polyene copolymer (A).

In the bridged metallocene compound (a) represented by the above general formula [I], n is preferably 1. Such a bridged metallocene compound (a-1) is represented by the following general formula [V].

(In formula [V], the definitions of Y, M, ^R1 , ^R2 , ^R3 , ^R4 , ^R5 , ^R6 , Q and j are as described above.)

Compared to the compound in the above general formula [I] in which n is an integer of 2 to 4, the bridged metallocene compound (a-1) has the advantage that the production process is simplified and the production cost is reduced, and thus the use of this bridged metallocene compound reduces the production cost of the ethylene-α-olefin-non-conjugated polyene copolymer (A). Furthermore, when ethylene, an α-olefin having 4 or more carbon atoms, and a non-conjugated polyene are copolymerized in the presence of an olefin polymerization catalyst containing the bridged metallocene compound (a-1), the resulting ethylene-α-olefin-non-conjugated polyene copolymer (A) has the advantage of having a high molecular weight.

In the bridged metallocene compound (a-1) represented by the above general formula [I], it is preferable that R ¹ , R ² , R ³ and R ⁴ are all hydrogen atoms. Such a bridged metallocene compound (a-2) is represented by the following general formula [VI].

(In formula [VI], the definitions of Y, M, R ⁵ , R ⁶ , Q and j are as described above.)

The bridged metallocene compound (a-2) has the advantage that the production process is simplified and the production cost is reduced, and thus the production cost of the ethylene ^/ α ^- olefin/non-conjugated polyene copolymer is reduced, as compared with a compound in which any one or more of R 1 , R ² , R 3 and R ⁴ in the above general formula [V] are substituted with a substituent other than a hydrogen atom. Furthermore, when ethylene, an α-olefin having 4 or more carbon atoms and a non-conjugated polyene are copolymerized in the presence of an olefin polymerization catalyst containing the bridged metallocene compound (a-2), the polymerization activity is improved and the molecular weight of the resulting ethylene/α-olefin/non-conjugated polyene copolymer (A) is increased. At the same time, the copolymerization performance of the non-conjugated polyene is improved.

In the bridged metallocene compound (a-2) represented by the above general formula [VI], Y is more preferably a carbon atom. Such a bridged metallocene compound (a-3) is represented by the following general formula [VII].

(In formula [VII], the definitions of M, R ⁵ , R ⁶ , Q and j are as described above.)
The bridged metallocene compound (a-3) can be synthesized by a simple method such as that shown in the following formula [VIII].

(In formula [VIII], the definitions of M, R ⁵ , and R ⁶ are as described above.)

In the above formula [VIII], ^R5 and ^R6 are atoms or substituents selected from hydrogen atoms, hydrocarbon groups having 1 to 20 carbon atoms, aryl groups, substituted aryl groups, silicon-containing groups, nitrogen-containing groups, oxygen-containing groups, halogen atoms and halogen-containing groups, and may be the same or different and may be bonded to each other to form a ring. Various ketones satisfying these conditions, represented by the general formula ^R5 -C(=O) ^-R6 , are commercially available from general reagent manufacturers, so that the raw materials for the bridged metallocene compound (a-3) are easily available. Even if such ketones are not commercially available, they can be easily synthesized, for example, by the method by Olah et al. [Heterocycles, 40, 79 (1995)]. Thus, the bridged metallocene compound (a-3) has a simpler and easier production process than a compound in which Y in the above general formula [V] is selected from a silicon atom, a germanium atom and a tin atom, and the production cost is further reduced, and thus the use of this bridged metallocene compound has the advantage of reducing the production cost of an ethylene copolymer. Furthermore, when ethylene, an α-olefin having 4 or more carbon atoms and a non-conjugated polyene are copolymerized in the presence of an olefin polymerization catalyst containing the bridged metallocene compound (a-3), the resulting ethylene-α-olefin-non-conjugated polyene copolymer (A) has a further higher molecular weight.

In the bridged metallocene compound (a-3) represented by the above general formula [VII], ^R5 and ^R6 are preferably groups selected from an aryl group and a substituted aryl group. When ethylene, an α-olefin having 4 or more carbon atoms, and a non-conjugated polyene are copolymerized in the presence of an olefin polymerization catalyst containing the bridged metallocene compound, the advantages of further improving the polymerization activity and further increasing the molecular weight of the resulting ethylene-α-olefin-non-conjugated polyene copolymer (A) are obtained. At the same time, the advantages of improving the copolymerization performance of the non-conjugated polyene are also obtained.

In the bridged metallocene compound (a-3) represented by the above general formula [VII], ^R5 and ^R6 are more preferably the same group selected from an aryl group and a substituted aryl group. By selecting ^R5 and ^R6 in this way, the synthesis process of the bridged metallocene compound is simplified, and the production cost is reduced, and the use of this bridged metallocene compound has the advantage of reducing the production cost of the ethylene copolymer.

In the bridged metallocene compound (a-3) represented by the above general formula [VII], ^R5 and ^R6 are more preferably the same substituted aryl group. When ethylene, an α-olefin having 4 or more carbon atoms, and a non-conjugated polyene are copolymerized in the presence of an olefin polymerization catalyst containing the bridged metallocene compound, the resulting ethylene-α-olefin-non-conjugated polyene copolymer (A) has an advantage of having a higher molecular weight.

In the bridged metallocene compound (a-3) represented by the above general formula [VII], R ⁵ and R ⁶ are substituted aryl groups in which one or more hydrogen atoms of the aryl group are substituted with an electron-donating substituent having a Hammett's rule substituent constant σ of -0.2 or less, and when the aryl group has a plurality of electron-donating substituents, the respective electron-donating substituents may be the same or different, and may have a substituent selected from a hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen atom, and a halogen-containing group other than the electron-donating substituent, and when the aryl group has a plurality of substituents, the respective substituents may be the same or different (hereinafter also referred to as "electron-donating group-containing substituted aryl group"). When ethylene, an α-olefin having 4 or more carbon atoms, and a non-conjugated polyene are copolymerized in the presence of an olefin polymerization catalyst containing the bridged metallocene compound, the resulting ethylene-α-olefin-non-conjugated polyene copolymer (A) has an advantage of further increasing its molecular weight.

Electron-donating groups with a Hammett's rule substituent constant σ of -0.2 or less are defined and exemplified as follows. The Hammett's rule is an empirical rule proposed by L. P. Hammett in 1935 to quantitatively discuss the effect of substituents on the reaction or equilibrium of benzene derivatives, and is now widely recognized as valid. The substituent constants obtained by the Hammett's rule include σp when substituted at the para position of the benzene ring and σm when substituted at the meta position, and these values can be found in many general literature. For example, the literature by Hansch and Taft [Chem. Rev., 91, 165 (1991)] provides detailed descriptions of a very wide range of substituents. However, the values of σp and σm described in these literatures may differ slightly depending on the literature, even for the same substituent. In the present invention, in order to avoid confusion caused by such a situation, the literature by Hansch and Taft [Chem. Rev. , 91, 165 (1991)], Table 1 (pp. 168-175) are defined as the substituent constants σp and σm of the Hammett rule. In the present invention, an electron donating group having a Hammett rule substituent constant σ of -0.2 or less is an electron donating group having a σp of -0.2 or less when the electron donating group is substituted at the para position (4th position) of a phenyl group, and an electron donating group having a σm of -0.2 or less when the electron donating group is substituted at the meta position (3rd position) of a phenyl group. In addition, when the electron donating group is substituted at the ortho position (2nd position) of a phenyl group or at any position of an aryl group other than a phenyl group, it is an electron donating group having a σp of -0.2 or less.

Examples of electron-donating substituents having a Hammett's rule substituent constant σp or σm of -0.2 or less include nitrogen-containing groups such as p-amino group (4-amino group), p-dimethylamino group (4-dimethylamino group), p-diethylamino group (4-diethylamino group), and m-diethylamino group (3-diethylamino group), oxygen-containing groups such as p-methoxy group (4-methoxy group) and p-ethoxy group (4-ethoxy group), tertiary hydrocarbon groups such as p-t-butyl group (4-t-butyl group), and silicon-containing groups such as p-trimethylsiloxy group (4-trimethylsiloxy group). The electron-donating substituents having a Hammett's rule substituent constant σp or σm of -0.2 or less as defined in the present invention are described in the literature by Hansch and Taft [Chem. Rev. , 91, 165 (1991)], Table 1 (pp. 168-175). Substituents not described in the document, whose substituent constants σp or σm would fall within that range when measured based on Hammett's rule, are included in the electron-donating groups whose Hammett's rule substituent constants σp or σm are −0.2 or less as defined in the present invention. Examples of such substituents include p-N-morpholinyl groups (4-N-morpholinyl groups) and m-N-morpholinyl groups (3-N-morpholinyl groups).

In an electron-donating group-containing substituted aryl group, when a plurality of electron-donating substituents are substituted, the respective electron-donating substituents may be the same or different, and in addition to the electron-donating substituents, the aryl group may be substituted with a substituent selected from a hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen atom, and a halogen-containing group. When a plurality of substituents are substituted, the respective substituents may be the same or different, but it is preferable that the sum of the substituent constants σ of the Hammett's rule of the electron-donating substituents and the respective substituents contained in one substituted aryl group is -0.15 or less. Examples of such substituted aryl groups include m,p-dimethoxyphenyl group (3,4-dimethoxyphenyl group), p-(dimethylamino)-m-methoxyphenyl group (4-(dimethylamino)-3-methoxyphenyl group), p-(dimethylamino)-m-methylphenyl group (4-(dimethylamino)-3-methylphenyl group), p-methoxy-m-methylphenyl group (4-methoxy-3-methylphenyl group), and p-methoxy-m,m-dimethylphenyl group (4-methoxy-3,5-dimethylphenyl group).

The electron-donating group-containing substituted aryl group may have a hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen atom, and a halogen-containing group, examples of which include the above-mentioned atoms and substituents.

The applicant has conducted extensive studies on various bridged metallocene compounds (a) and has found that when R ⁵ and R ⁶ in the bridged metallocene compound (a-3) represented by the above general formula [VII] are, in particular, an electron-donating group-containing substituted aryl group substituted with one or more electron-donating substituents having a Hammett's rule substituent constant σ of -0.2 or less, the molecular weight of the resulting ethylene-α-olefin-non-conjugated polyene copolymer (A) becomes higher when ethylene, an α-olefin having 4 or more carbon atoms, and a non-conjugated polyene are copolymerized in the presence of an olefin polymerization catalyst containing the bridged metallocene compound (a-3).

In the coordination polymerization of olefins using an organometallic complex catalyst such as the bridged metallocene compound (a-3), it is known that the molecular chain of the olefin polymer containing the ethylene-α-olefin-non-conjugated polyene copolymer (A) produced grows (growth reaction) as the olefin polymer repeatedly polymerizes on the central metal of the catalyst, and the molecular weight of the olefin polymer increases. On the other hand, it is also known that in a reaction called chain transfer, the molecular chain of the olefin polymer dissociates from the central metal of the catalyst, and the growth reaction of the molecular chain stops, and therefore the increase in the molecular weight of the olefin polymer also stops. From the above, the molecular weight of an olefin polymer is characterized by the ratio of the frequency of the propagation reaction to the frequency of the chain transfer reaction, which is specific to the organometallic complex catalyst that produces it. That is, the higher the ratio of the frequency of the propagation reaction to the frequency of the chain transfer reaction, the higher the molecular weight of the olefin polymer produced, and conversely, the lower the ratio, the lower the molecular weight. Here, the frequency of each reaction can be estimated from the activation energy of each reaction, and it is considered that a reaction with a low activation energy has a high frequency, and a reaction with a high activation energy has a low frequency. In general, it is known that the frequency of the propagation reaction in olefin polymerization is sufficiently higher than the frequency of the chain transfer reaction, that is, the activation energy of the propagation reaction is sufficiently lower than the activation energy of the chain transfer reaction. Therefore, the value obtained by subtracting the activation energy of the propagation reaction from the activation energy of the chain transfer reaction (hereinafter, ΔE _C ) is positive, and it is estimated that the larger this value is, the higher the frequency of the propagation reaction is compared to the frequency of the chain transfer reaction, and the higher the molecular weight of the resulting olefin polymer. The validity of the estimation of the molecular weight of the olefin polymer performed in this manner is also supported by the calculation results of, for example, Laine et al. [Organometallics, 30, 1350 (2011)].

In the bridged metallocene compound (a-3) represented by the above general formula [VII], when R ⁵ and R ⁶ are, in particular, an electron-donating group-containing substituted aryl group substituted with one or more electron-donating substituents having a Hammett's rule substituent constant σ of -0.2 or less, it is presumed that the above ΔE _C increases, and when ethylene, an α-olefin having 4 or more carbon atoms, and a non-conjugated polyene are copolymerized in the presence of an olefin polymerization catalyst containing the bridged metallocene compound (a-3), the molecular weight of the produced ethylene-α-olefin-non-conjugated polyene copolymer (A) increases.

In the bridged metallocene compound (a-3) represented by the above general formula [VII], the electron-donating substituents contained in R ⁵ and R ⁶ are more preferably groups selected from nitrogen-containing groups and oxygen-containing groups.

In the bridged metallocene compound (a-3) represented by the above general formula [VII], ^R5 and ^R6 are more preferably substituted phenyl groups containing a group selected from a nitrogen-containing group and an oxygen-containing group as the electron-donating substituent. For example, when synthesizing according to the method of the above formula [VIII], various benzophenones as raw materials are commercially available from general reagent manufacturers, so that raw materials are easily available, the production process is simplified, and the production cost is reduced. In addition, the use of this bridged metallocene compound has the advantage of reducing the production cost of the ethylene-α-olefin-non-conjugated polyene copolymer (A).

Here, examples of the substituted phenyl group containing a group selected from the nitrogen-containing group and the oxygen-containing group as the electron-donating substituent include an o-aminophenyl group (2-aminophenyl group), a p-aminophenyl group (4-aminophenyl group), an o-(dimethylamino)phenyl group (2-(dimethylamino)phenyl group), a p-(dimethylamino)phenyl group (4-(dimethylamino)phenyl group), an o-(diethylamino)phenyl group (2-(diethylamino)phenyl group), a p-(diethylamino)phenyl group (4-(diethylamino)phenyl group), a m-(diethylamino)phenyl group (3-(diethylamino)phenyl group), an o-methoxyphenyl group (2-methoxyphenyl group), a p-methoxyphenyl group (4-methoxyphenyl group), an o-ethoxyphenyl group (2-ethoxyphenyl group), a p-ethoxyphenyl group (4 -ethoxyphenyl group), o-N-morpholinylphenyl group (2-N-morpholinylphenyl group), p-N-morpholinylphenyl group (4-N-morpholinylphenyl group), m-N-morpholinylphenyl group (3-N-morpholinylphenyl group), o,p-dimethoxyphenyl group (2,4-dimethoxyphenyl group), m,p-dimethoxyphenyl group (3,4-dimethoxyphenyl group), p-(dimethylamino)-m-methoxyphenyl group (4-(dimethylamino)-3-methoxyphenyl group), p-(dimethylamino)-m-methylphenyl group (4-(dimethylamino)-3-methylphenyl group), p-methoxy-m-methylphenyl group (4-methoxy-3-methylphenyl group), p-methoxy-m,m-dimethylphenyl group (4-methoxy-3,5-dimethylphenyl group), etc. are examples.

In the bridged metallocene compound (a-3) represented by the above general formula [VII], ^R5 and ^R6 are more preferably substituted phenyl groups containing a group selected from a nitrogen-containing group and an oxygen-containing group as the electron-donating substituent at the meta-position and/or para-position with respect to the bond to the carbon atom represented by Y. For example, when synthesis is performed according to the method of the above formula [VIII], synthesis is easier than when the group is substituted at the ortho-position, the production process is simplified, and further the production cost is reduced, and thus the use of this bridged metallocene compound has the advantage of reducing the production cost of the ethylene copolymer.

In the bridged metallocene compound (a-3) represented by the above general formula [VII], when ^R5 and ^R6 are substituted phenyl groups containing a nitrogen-containing group as the electron-donating substituent at the meta-position and/or para-position with respect to the bond to the carbon atom represented by Y, it is more preferable that the nitrogen-containing group is a group represented by the following general formula [II].

(In formula [II], R ⁷ and R ⁸ are atoms or substituents selected from a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, an oxygen-containing group and a halogen-containing group, and may be the same or different and may be bonded to each other to form a ring, and the line drawn to the right of N represents a bond to a phenyl group.)

Examples of the hydrocarbon group having 1 to 20 carbon atoms, the silicon-containing group, the oxygen-containing group and the halogen-containing group represented by R ⁷ and R ⁸ include the specific examples of these substituents mentioned above.
Such a bridged metallocene compound (a-4) is represented by the following general formula [IX].

(In formula [IX], the definitions of M, Q and j are as described above. R ⁷ , R ⁸ and R ¹⁰ are substituents selected from a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen atom and a halogen-containing group, and may be the same or different, adjacent substituents among R ⁷ , R ⁸ and R ¹⁰ may be bonded to each other to form a ring, NR ⁷ R ⁸ is a nitrogen-containing group having a Hammett's substituent constant σ of −0.2 or less, and when a plurality of nitrogen-containing groups are present, the respective nitrogen-containing groups may be the same or different, n is an integer of 1 to 3, and m is an integer of 0 to 4.)

In the bridged metallocene compound (a-3) represented by the above general formula [VII], when ^R5 and ^R6 are substituted phenyl groups containing an oxygen-containing group as the electron-donating substituent at the meta-position and/or para-position with respect to the bond to the carbon atom represented by Y, it is more preferable that the oxygen-containing group is a group represented by the following general formula [III].

(In formula [III], R ⁹ is an atom or a substituent selected from a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a nitrogen-containing group and a halogen-containing group, and the line drawn to the right of O represents a bond to a phenyl group.)

Examples of the hydrocarbon group having 1 to 20 carbon atoms, the silicon-containing group, the nitrogen-containing group and the halogen-containing group as R ⁹ include the specific examples of these substituents mentioned above.
Such a bridged metallocene compound (a-5) is represented by the following general formula [X].

(In formula [X], the definitions of M, Q and j are as described above. R ⁹ and R ¹⁰ are atoms or substituents selected from a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a nitrogen-containing group, an oxygen-containing group, a halogen atom and a halogen-containing group, and may be the same or different, adjacent substituents of R ¹⁰ may be bonded to each other to form a ring, OR ⁹ is an oxygen-containing group having a Hammett's rule substituent constant of σ-0.2 or less, and when a plurality of oxygen-containing groups are present, the respective oxygen-containing groups may be the same or different, n is an integer of 1 to 3, and m is an integer of 0 to 4.)

In the bridged metallocene compound (a) represented by the above general formula [I], the bridged metallocene compound (a-1) represented by the above general formula [V], the bridged metallocene compound (a-2) represented by the above general formula [VI], the bridged metallocene compound (a-3) represented by the above general formula [VII], the bridged metallocene compound (a-4) represented by the above general formula [IX], or the bridged metallocene compound (a-5) represented by the above general formula [X], M is more preferably a hafnium atom. When ethylene, an α-olefin having 4 or more carbon atoms, and a non-conjugated polyene are copolymerized in the presence of an olefin polymerization catalyst containing the above bridged metallocene compound in which M is a hafnium atom, the resulting ethylene-α-olefin-non-conjugated polyene copolymer (A) has the advantage of having a higher molecular weight and improving the copolymerization performance of the non-conjugated polyene.

(Examples of bridged metallocene compound (a))
Examples of such bridged metallocene compounds (a) include
[dimethylmethylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [diethylmethylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [di-n-butylmethylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [dicyclopentylmethylene(η ^{5 -cyclopentadienyl)(η 5} -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [dicyclohexylmethylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride ^,
[cyclopentylidene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [cyclohexylidene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride,
[diphenylmethylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [di-1-naphthylmethylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [di-2-naphthylmethylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride,
[bis(3-methylphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-methylphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(3,4-dimethylphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-n-hexylphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-cyclohexylphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-t-butylphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride,
[bis(3-methoxyphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-methoxyphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(3,4-dimethoxyphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-methoxy-3-methylphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-methoxy-3,4-dimethylphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-ethoxyphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-phenoxyphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis{4-(trimethylsiloxy)phenyl}methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride,
[bis{3-(dimethylamino)phenyl}methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis{4-(dimethylamino)phenyl}methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-N-morpholinylphenyl)(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride,
[bis{4-(trimethylsilyl)phenyl}methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride,
[bis(3-chlorophenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-chlorophenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(3-fluorophenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis(4-fluorophenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis{3-(trifluoromethyl)phenyl}methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [bis{4-(trifluoromethyl)phenyl}methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride,
[methylphenylmethylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [methyl(4-methylphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [methyl(4-methoxyphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [methyl{4-(dimethylamino)phenyl}methylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [methyl(4-N-morpholinylphenyl)methylene(η ⁵ -cyclopentadienyl)(η ⁵ (-2,3,6,7-tetramethylfluorenyl)hafnium dichloride,
[dimethylsilylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [diethylsilylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [dicyclohexylsilylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [diphenylsilylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [di(4-methylphenyl)silylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride,
[dimethylgermylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride, [diphenylgermylene(η ⁵ -cyclopentadienyl)(η ⁵ -2,3,6,7-tetramethylfluorenyl)]hafnium dichloride,
[1-(η ⁵ -cyclopentadienyl)-2-(η ⁵ -2,3,6,7-tetramethylfluorenyl)ethylene]hafnium dichloride, [1-(η ⁵ -cyclopentadienyl)-3-(η ⁵ -2,3,6,7-tetramethylfluorenyl)propylene]hafnium dichloride, [1-(η ⁵ -cyclopentadienyl)-2-(η ⁵ -2,3,6,7-tetramethylfluorenyl)-1,1,2,2-tetramethylsilylene]hafnium dichloride, [1-(η ⁵ -cyclopentadienyl)-2-(η ⁵ [0033] Examples of the bridged metallocene compound (a) include [0033] hafnium dichloride, and compounds in which the hafnium atom of these compounds is replaced with a zirconium atom, or compounds in which the chloro ligand is replaced with a methyl group, but the bridged metallocene compound (a) is not limited to these examples.

<Method for Producing Bridged Metallocene Compound>
The bridged metallocene compound can be produced by a known method, and the production method is not particularly limited. For example, the bridged metallocene compound can be produced by the methods described in J. Organomet. Chem., 63,509 (1996), WO2006/123759, WO01/27124, JP-A-2004-168744, JP-A-2004-175759, JP-A-2000-212194, etc., which are publications related to applications filed by the present applicant.

<Preferable form when the bridged metallocene compound is used as a catalyst for the ethylene/α-olefin/non-conjugated polyene copolymer (A)>
Next, a preferred embodiment in which the above-mentioned bridged metallocene compound is used as a catalyst for the ethylene/α-olefin/non-conjugated polyene copolymer (A) (olefin polymerization catalyst) will be described.

When a bridged metallocene compound is used as an olefin polymerization catalyst component, the catalyst is
(a) a bridged metallocene compound represented by the general formula [I];
(b) at least one compound selected from (b-1) an organometallic compound, (b-2) an organoaluminum oxy compound, and (b-3) a compound that reacts with the bridged metallocene compound (a) to form an ion pair;
Furthermore, if necessary,
(c) A particulate carrier.

Each component will be specifically described below.
<(b-1) Organometallic compound>
As the organometallic compound (b-1) used in the present invention, specifically, organometallic compounds of Groups 1, 2, 12 and 13 of the periodic table, such as those represented by the following general formulas [VII] to [IX], are used.

(b-1a) General formula R ^a _m Al (OR ^b ) _n H _p X _q ... [VII]

(in formula [VII], R ^a and R ^b may be the same or different and each represent a hydrocarbon group having 1 to 15, preferably 1 to 4, carbon atoms; X represents a halogen atom; m is 0<m≦3, n is 0≦n<3, p is 0≦p<3, q is a number that satisfies 0≦q<3, and m+n+p+q=3).

Examples of such compounds include trialkylaluminums such as trimethylaluminum, triethylaluminum, triisobutylaluminum, and tri-n-octylaluminum, tricycloalkylaluminums, isobutylaluminum dichloride, diethylaluminum chloride, ethylaluminum dichloride, ethylaluminum sesquichloride, methylaluminum dichloride, dimethylaluminum chloride, and diisobutylaluminum hydride.

(b-1b) General formula M ² AlR ^a ₄ ...[VIII]

(In the formula [VIII], ^M2 represents Li, Na or K, and R ^a represents a hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms.) A complex alkylation product of aluminum and a metal of Group 1 of the periodic table.

Examples of such compounds include LiAl(C ₂ H ₅ ) ₄ and LiAl(C ₇ H ₁₅ ) ₄ .

(b-1c) General formula R ^a R ^b M ³ ...[IX]

(In formula [IX], R ^a and R ^b may be the same or different and represent a hydrocarbon group having 1 to 15, preferably 1 to 4, carbon atoms, and M ³ is Mg, Zn, or Cd.) A dialkyl compound having a metal of Group 2 or Group 12 of the Periodic Table.

Among the above organometallic compounds (b-1), organoaluminum compounds such as triethylaluminum, triisobutylaluminum, and tri-n-octylaluminum are preferred. Furthermore, such organometallic compounds (b-1) may be used alone or in combination of two or more.

(b-2) Organoaluminum Oxy Compound
The organoaluminum oxy compound (b-2) used in the present invention may be a conventionally known aluminoxane, or may be a benzene-insoluble organoaluminum oxy compound such as those exemplified in JP-A-2-78687.

Conventionally known aluminoxanes can be produced, for example, by the following method, and are usually obtained as a solution in a hydrocarbon solvent.
(1) A method in which an organoaluminum compound such as trialkylaluminum is added to a hydrocarbon medium suspension of a compound containing adsorbed water or a salt containing water of crystallization, such as magnesium chloride hydrate, copper sulfate hydrate, aluminum sulfate hydrate, nickel sulfate hydrate, or cerous chloride hydrate, to react the adsorbed water or the water of crystallization with the organoaluminum compound.
(2) A method in which water, ice or water vapor is allowed to directly act on an organoaluminum compound such as trialkylaluminum in a medium such as benzene, toluene, ethyl ether or tetrahydrofuran.
(3) A method in which an organoaluminum compound such as trialkylaluminum is reacted with an organotin oxide such as dimethyltin oxide or dibutyltin oxide in a medium such as decane, benzene or toluene.

The aluminoxane may contain a small amount of an organometallic component. After the solvent or unreacted organoaluminum compound is removed by distillation from the recovered aluminoxane solution, the aluminoxane may be redissolved in a solvent or suspended in a poor solvent for the aluminoxane.

Specific examples of organoaluminum compounds used in preparing aluminoxanes include the same organoaluminum compounds as those exemplified as organoaluminum compounds belonging to (b-1a) above.

Of these, trialkylaluminum and tricycloalkylaluminum are preferred, and among these, trimethylaluminum and triisobutylaluminum are particularly preferred.
The above organoaluminum compounds may be used singly or in combination of two or more.

The benzene-insoluble organoaluminum oxy-compound (b-2), which is one embodiment of the organoaluminum oxy-compound used in the present invention, is preferably one in which the Al component soluble in benzene at 60°C is usually 10% by weight or less, preferably 5% by weight or less, and particularly preferably 2% by weight or less, calculated as Al atoms, relative to 100% by weight of benzene, i.e., one which is insoluble or poorly soluble in benzene.

The organoaluminum oxy compound (b-2) used in the present invention may also be an organoaluminum oxy compound containing boron represented by the following general formula [X].

(In formula [X], R ¹ represents a hydrocarbon group having 1 to 10 carbon atoms, and R ² to R ⁵ may be the same or different and represent a hydrogen atom, a halogen atom, or a hydrocarbon group having 1 to 10 carbon atoms.)

The organoaluminum oxy compound containing boron represented by the general formula [X] is a compound obtained by mixing an alkylboronic acid represented by the following general formula [XI] with
R ¹ -B(OH) ₂ ... [XI]
(In formula [XI], R ¹ represents the same group as R ¹ in general formula [X].)
The compound can be produced by reacting the compound with an organoaluminum compound in an inert solvent under an inert gas atmosphere at a temperature of from -80°C to room temperature for 1 minute to 24 hours.

Specific examples of the alkylboronic acid represented by the general formula [XI] include methylboronic acid, ethylboronic acid, isopropylboronic acid, n-propylboronic acid, n-butylboronic acid, isobutylboronic acid, n-hexylboronic acid, cyclohexylboronic acid, phenylboronic acid, 3,5-difluorophenylboronic acid, pentafluorophenylboronic acid, and 3,5-bis(trifluoromethyl)phenylboronic acid.

Among these, methylboronic acid, n-butylboronic acid, isobutylboronic acid, 3,5-difluorophenylboronic acid, and pentafluorophenylboronic acid are preferred. These may be used alone or in combination of two or more.

Specific examples of organoaluminum compounds to be reacted with such alkylboronic acids include the same organoaluminum compounds as those exemplified as the organoaluminum compounds belonging to (b-1a) above.

Of these, trialkylaluminum and tricycloalkylaluminum are preferred, and trimethylaluminum, triethylaluminum and triisobutylaluminum are particularly preferred. These may be used alone or in combination of two or more. The organoaluminum oxy compounds (b-2) as described above may be used alone or in combination of two or more.

<(b-3) Compound that reacts with transition metal compound (a) to form an ion pair>
Examples of the compound (b-3) (hereinafter referred to as "ionizing ionic compound") that reacts with the bridged metallocene compound (a) to form an ion pair include Lewis acids, ionic compounds, borane compounds, and carborane compounds described in JP-T-1-501950, JP-T-1-502036, JP-A-3-179005, JP-A-3-179006, JP-A-3-207703, JP-A-3-207704, and USP-5321106. Further examples include heteropoly compounds and isopoly compounds. Such ionizing ionic compounds (b-3) may be used alone or in combination of two or more.

Specifically, Lewis acids include compounds represented by _BR3 (R is fluorine or a phenyl group which may have a substituent such as fluorine, a methyl group or a trifluoromethyl group), such as trifluoroboron, triphenylboron, tris(4-fluorophenyl)boron, tris(3,5-difluorophenyl)boron, tris(4-fluoromethylphenyl)boron, tris(pentafluorophenyl)boron, tris(p-tolyl)boron, tris(o-tolyl)boron, and tris(3,5-dimethylphenyl)boron.

An example of an ionic compound is a compound represented by the following general formula [XII].

(In formula [XII], R ¹⁺ includes H ⁺ , a carbonium cation, an oxonium cation, an ammonium cation, a phosphonium cation, a cycloheptyltrienyl cation, a ferrocenium cation having a transition metal, and the like. R ² to R ⁵ may be the same or different and each represents an organic group, preferably an aryl group or a substituted aryl group.)

Specific examples of the carbonium cation include tri-substituted carbonium cations such as triphenylcarbonium cation, tri(methylphenyl)carbonium cation, and tri(dimethylphenyl)carbonium cation.

Specific examples of the ammonium cation include trialkylammonium cations such as trimethylammonium cation, triethylammonium cation, tripropylammonium cation, tributylammonium cation, and tri(n-butyl)ammonium cation;
N,N-dialkylanilinium cations such as N,N-dimethylanilinium cation, N,N-diethylanilinium cation, and N,N,2,4,6-pentamethylanilinium cation;
Examples of the cation include dialkylammonium cations such as di(isopropyl)ammonium cation and dicyclohexylammonium cation.

Specific examples of the phosphonium cation include triarylphosphonium cations such as triphenylphosphonium cation, tri(methylphenyl)phosphonium cation, and tri(dimethylphenyl)phosphonium cation.

As R ¹⁺ , a carbonium cation, an ammonium cation, etc. are preferred, and a triphenylcarbonium cation, an N,N-dimethylanilinium cation, or an N,N-diethylanilinium cation is particularly preferred.

Other examples of ionic compounds include trialkyl-substituted ammonium salts, N,N-dialkylanilinium salts, dialkylammonium salts, and triarylphosphonium salts.

Specific examples of trialkyl-substituted ammonium salts include triethylammonium tetra(phenyl)boron, tripropylammonium tetra(phenyl)boron, tri(n-butyl)ammonium tetra(phenyl)boron, trimethylammonium tetra(p-tolyl)boron, trimethylammonium tetra(o-tolyl)boron, tri(n-butyl)ammonium tetra(pentafluorophenyl)boron, tripropylammonium tetra(o,p-dimethylphenyl)boron, tri(n-butyl)ammonium tetra(N,N-dimethylphenyl)boron, tri(n-butyl)ammonium tetra(p-trifluoromethylphenyl)boron, tri(n-butyl)ammonium tetra(3,5-ditrifluoromethylphenyl)boron, and tri(n-butyl)ammonium tetra(o-tolyl)boron.

Specific examples of N,N-dialkylanilinium salts include N,N-dimethylanilinium tetra(phenyl)boron, N,N-diethylanilinium tetra(phenyl)boron, and N,N,2,4,6-pentamethylanilinium tetra(phenyl)boron.

Specific examples of dialkylammonium salts include di(1-propyl)ammonium tetra(pentafluorophenyl)boron and dicyclohexylammonium tetra(phenyl)boron.

Further examples of ionic compounds include triphenylcarbenium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, ferrocenium tetra(pentafluorophenyl)borate, triphenylcarbenium pentaphenylcyclopentadienyl complex, N,N-diethylanilinium pentaphenylcyclopentadienyl complex, and boron compounds represented by the following formula [XIII] or [XIV].

（式中、Ｅｔはエチル基を示す。）

(In the formula, Et represents an ethyl group.)

（式中、Ｅｔはエチル基を示す。）

(In the formula, Et represents an ethyl group.)

Specific examples of the borane compound include decaborane;
Salts of anions such as bis[tri(n-butyl)ammonium]nonaborate, bis[tri(n-butyl)ammonium]decaborate, bis[tri(n-butyl)ammonium]undecaborate, bis[tri(n-butyl)ammonium]dodecaborate, bis[tri(n-butyl)ammonium]decachlorodecaborate, and bis[tri(n-butyl)ammonium]dodecachlorododecaborate;
Examples of the salt include salts of metal borane anions such as tri(n-butyl)ammonium bis(dodecahydride dodecaborate) cobaltate (III) and bis[tri(n-butyl)ammonium]bis(dodecahydride dodecaborate) nickelate (III).

Specific examples of the carborane compound include 4-carbanonaborane, 1,3-dicarbanonaborane, 6,9-dicarbadecaborane, dodecahydride-1-phenyl-1,3-dicarbanonaborane, dodecahydride-1-methyl-1,3-dicarbanonaborane, undecahydride-1,3-dimethyl-1,3-dicarbanonaborane, 7,8-dicarbaundecaborane, 2,7-dicarbaundecaborane, and undecahydride-7,8-dimethyl-7,8- Dicarbaundecaborane, dodecahydride-11-methyl-2,7-dicarbaundecaborane, tri(n-butyl)ammonium 1-carbadecaborate, tri(n-butyl)ammonium-1-carbaundecaborate, tri(n-butyl)ammonium-1-carbadodecaborate, tri(n-butyl)ammonium-1-trimethylsilyl-1-carbadecaborate, tri(n-butyl)ammonium bromo-1-carbadodecaborate, tri(n-butyl) Ammonium-6-carbadecaborate, tri(n-butyl)ammonium-7-carboundecaborate, tri(n-butyl)ammonium-7,8-dicarboxaborate, tri(n-butyl)ammonium-2,9-dicarboxaborate, tri(n-butyl)ammonium dodecahydride-8-methyl-7,9-dicarboxaborate, tri(n-butyl)ammonium undecahydride-8-ethyl-7,9-dicarboxaborate , tri(n-butyl)ammonium undecahydride-8-butyl-7,9-dicarboxaundecaborate, tri(n-butyl)ammonium undecahydride-8-allyl-7,9-dicarboxaundecaborate, tri(n-butyl)ammonium undecahydride-9-trimethylsilyl-7,8-dicarboxaundecaborate, tri(n-butyl)ammonium undecahydride-4,6-dibromo-7-carbaundecaborate, and other anionic salts;
Tri(n-butyl)ammonium bis(nonahydride-1,3-dicarbanonaborate)cobaltate(III), tri(n-butyl)ammonium bis(undecahydride-7,8-dicarbandecaborate)ferrate(III), tri(n-butyl)ammonium bis(undecahydride-7,8-dicarbandecaborate)cobaltate(III), tri(n-butyl)ammonium bis(undecahydride-7,8-dicarbandecaborate)nickelate(III), tri(n-butyl)ammonium bis(undecahydride-7,8-dicarbandecaborate)cuprate(III), tri(n-butyl)ammonium bis(undecahydride-7,8-dicarbandecaborate)aurate(III), tri(n-butyl)ammonium bis(nonahydride-7,8-dimethyl-7,8-dicarbandecaborate)ferrate salt (III), tri(n-butyl)ammonium bis(nonahydride-7,8-dimethyl-7,8-dicarboxecaporate)chromate (III), tri(n-butyl)ammonium bis(tribromooctahydride-7,8-dicarboxecaporate)cobaltate (III), tris[tri(n-butyl)ammonium]bis(undecahydride-7-carbowndecaborate)chromate (III), bis[tri(n-butyl)ammonium]bis(undecahydride-7-carbowndecaborate)manganate (IV), bis[tri(n-butyl)ammonium]bis(undecahydride-7-carbowndecaborate)cobaltate (III), and bis[tri(n-butyl)ammonium]bis(undecahydride-7-carbowndecaborate)nickelate (IV).

The heteropoly compound is composed of atoms selected from silicon, phosphorus, titanium, germanium, arsenic and tin, and one or more atoms selected from vanadium, niobium, molybdenum and tungsten. Specifically, phosphovanadic acid, germanovanadic acid, arsenic vanadic acid, phosphoniobic acid, germanoniobic acid, siliconomolybdic acid, phosphomolybdic acid, titanomolybdic acid, germanomolybdic acid, arsenic molybdic acid, tinmolybdic acid, phosphotungstic acid, germanotungstic acid, tintungstic acid, phosphomolybdovanadic acid, phosphotungstovanadic acid, germanotungstovanadic acid, phosphomolybdotungstovanadic acid, germanomolybdotungstovanadic acid, phosphomolybdotungstic acid, phosphomolybdoniobic acid, and salts of these acids, such as salts with metals of Group 1 or 2 of the periodic table, specifically, lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, etc., and organic salts such as triphenylethyl salts can be used, but are not limited to these.

Of the ionizing ionic compounds (b-3), the above-mentioned ionic compounds are preferred, and among them, triphenylcarbenium tetrakis(pentafluorophenyl)borate and N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate are more preferred.
The ionizing ionic compounds (b-3) may be used singly or in combination of two or more.

When the transition metal compound (a) represented by the above general formula [I] is used as a catalyst, it shows extremely high polymerization activity in the production of ethylene-α-olefin-non-conjugated polyene copolymers when used in combination with an organometallic compound (b-1) such as triisobutylaluminum, an organoaluminum oxy compound (b-2) such as methylaluminoxane, or an ionizing ionic compound (b-3) such as triphenylcarbenium tetrakis(pentafluorophenyl)borate.

The olefin polymerization catalyst may also contain the transition metal compound (a) and at least one compound (b) selected from (b-1) an organometallic compound, (b-2) an organoaluminum oxy compound, and (b-3) an ionizing ionic compound, and, if necessary, a carrier (c).

(c) Carrier
In the present invention, the carrier (c) used as necessary is an inorganic or organic compound, and is a granular or fine particle solid.

Of these, the inorganic compound is preferably a porous oxide, an inorganic halide, a clay, a clay mineral or an ion-exchangeable layered compound.
As the porous oxide, specifically, _SiO2 , _Al2O3 , _MgO , ZrO, _TiO2 , _B2O3 , CaO, ZnO, BaO, _ThO2, etc., or _a composite or mixture containing these, such _as natural or synthetic zeolite, SiO2 _- MgO, SiO2- _Al2O3 , SiO2 _{- TiO2} , _{SiO2 - V2O5} , SiO2 _{- Cr2O3} , SiO2 _{- TiO2 - MgO} , etc., can be used. Among these, those containing _SiO2 and/or _Al2O3 as _the main component are preferred. The properties of such porous oxides vary depending on the type and production method, but the carriers preferably used in the present invention have a particle size of 10 to 300 μm, preferably 20 to 200 μm, a specific surface area of 50 to 1000 m ² /g, preferably 100 to 700 ^{m 2} /g, and a pore volume of 0.3 to 3.0 cm ³ /g. Such carriers are calcined at 100 to 1000° C., preferably 150 to 700° C., if necessary, before use.

Examples of inorganic halides that can be used include _MgCl2 , _MgBr2 , _MnCl2 , and _MnBr2 . The inorganic halides may be used as they are, or may be used after being pulverized by a ball mill or a vibration mill. Alternatively, the inorganic halides may be dissolved in a solvent such as alcohol, and then precipitated into fine particles using a precipitating agent.
Clay is usually composed mainly of clay minerals. An ion-exchangeable layered compound is a compound having a crystal structure in which the planes formed by ionic bonds are stacked in parallel with each other with weak bonding force, and the ions contained therein are exchangeable. Most clay minerals are ion-exchangeable layered compounds. These clays, clay minerals, and ion-exchangeable layered compounds are not limited to natural products, and artificial synthetic products can also be used.

Examples of clay, clay minerals, or ion-exchangeable layered compounds include clay, clay minerals, and ionic crystalline compounds having layered crystal structures such as hexagonal close packing type, antimony type, _CdCl2 type, and _CdI2 type. Examples of such clays and clay minerals include kaolin, bentonite, kibushi clay, gairome clay, allophane, hisingerite, pyrophyllite, unmo group, montmorillonite group, vermiculite, ryokudeite group, palygorskite, kaolinite, nacrite, dickite, halloysite, and the like. Examples of ion-exchangeable layered compounds include α-Zr(HAsO ₄ ) _{2.H 2 O} , α-Zr(HPO ₄ ) ₂ , α-Zr(KPO ₄ ) _{2.3H 2} O, α-Ti(HPO ₄ ) ₂ , α-Ti(HAsO ₄ ) _{2.H 2} O, α-Sn(HPO ₄ ) _{2.H 2 O} , γ-Zr(HPO ₄ ) ₂ , γ-Ti(HPO ₄ ) ₂ and crystalline acid salts of polyvalent metals such as γ-Ti(NH ₄ PO ₄ ) ₂ ·H ₂ O.

Such clays, clay minerals, or ion-exchangeable layered compounds preferably have a pore volume of 0.1 cc/g or more, particularly preferably 0.3 to 5 cc/g, having a radius of 20 Å or more, as measured by mercury intrusion porosimetry. Here, the pore volume is measured for a pore radius range of 20 to 30,000 Å by mercury intrusion porosimetry using a mercury porosimeter.
When a carrier having a pore volume of less than 0.1 cc/g and a radius of 20 Å or more is used, it tends to be difficult to obtain high polymerization activity.

It is also preferable to subject clay and clay minerals to chemical treatment. Any of the following chemical treatments can be used: surface treatment to remove impurities adhering to the surface, and treatment to affect the clay's crystal structure. Specific examples of chemical treatments include acid treatment, alkali treatment, salt treatment, and organic treatment. Acid treatment removes surface impurities and increases the surface area by dissolving cations such as Al, Fe, and Mg in the crystal structure. Alkaline treatment destroys the clay's crystal structure, resulting in a change in the clay's structure. Salt treatment and organic treatment also form ion complexes, molecular complexes, and organic derivatives, which can change the surface area and interlayer distance.

The ion-exchangeable layered compound may be a layered compound in which the space between layers is expanded by exchanging the exchangeable ions between layers with other large bulky ions by utilizing the ion exchangeability. Such bulky ions play a role of supporting the layered structure and are usually called pillars. The introduction of another substance between layers of a layered compound in this way is called intercalation. Examples of guest compounds to be intercalated include cationic inorganic compounds such as TiCl ₄ and ZrCl ₄ , metal alkoxides such as Ti(OR) ₄ , Zr(OR) ₄ , PO(OR) ₃ and B(OR) ₃ (R is a hydrocarbon group, etc.), and metal hydroxide ions such as [Al ₁₃ O ₄ (OH) ₂₄ ] ⁷⁺ , [Zr ₄ (OH) ₁₄ ] ²⁺ and [Fe ₃ O(OCOCH ₃ ) ₆ ] ⁺ . These compounds may be used alone or in combination of two or more. In addition, when intercalating these compounds, polymers obtained by hydrolysis of metal alkoxides (R is a hydrocarbon group, etc.) such as Si(OR) ₄ , Al(OR) ₃ , and Ge(OR) ₄ , and colloidal inorganic compounds such as SiO ₂ can be coexisted. Examples of pillars include oxides generated by intercalating the above metal hydroxide ions between layers and then dehydrating them with heat.

The clay, clay minerals, and ion-exchangeable layered compounds may be used as is, or after treatment such as ball milling or sieving. They may also be used after adding and adsorbing new water, or after heat dehydration treatment. Furthermore, they may be used alone or in combination of two or more kinds.

Of these, clay or clay minerals are preferred, and montmorillonite, vermiculite, hectorite, taeniolite and synthetic mica are particularly preferred.
The organic compound may be a granular or particulate solid having a particle size in the range of 10 to 300 μm. Specifically, examples include (co)polymers produced mainly from α-olefins having 2 to 14 carbon atoms, such as ethylene, propylene, 1-butene, and 4-methyl-1-pentene, or (co)polymers produced mainly from vinylcyclohexane and styrene, and modified products thereof.

The olefin polymerization catalyst used in the present invention may contain a bridged metallocene compound (a), at least one compound (b) selected from (b-1) an organometallic compound, (b-2) an organoaluminum oxy compound, and (b-3) an ionizing ionic compound, and a carrier (c) that is used as needed.

<Method for polymerizing monomers in the presence of a catalyst for ethylene-α-olefin-non-conjugated polyene copolymer>
When ethylene, an α-olefin having 4 to 20 carbon atoms, and a non-conjugated polyene are copolymerized, the method of using each component constituting the polymerization catalyst and the order of addition may be arbitrarily selected, but the following method is exemplified.
(1) The compound (a) is added alone to a polymerization reactor.
(2) The compound (a) and the compound (b) are added to a polymerization vessel in any order.
(3) A method in which the catalyst component in which the compound (a) is supported on the carrier (c) and the compound (b) are added to a polymerization vessel in any order.
(4) A method in which the catalyst component in which the compound (b) is supported on the carrier (c) and the compound (a) are added to a polymerization vessel in any order.
(5) A method in which a catalyst component in which the compound (a) and the compound (b) are supported on the carrier (c) is added to a polymerization vessel.

In each of the above methods (2) to (5), at least two of compound (a), compound (b), and carrier (c) may be in contact with each other in advance.

In the above methods (4) and (5) in which the compound (b) is supported, the unsupported compound (b) may be added in any order as necessary. In this case, the compound (b) may be the same as or different from the compound (b) supported on the carrier (c).

In addition, the solid catalyst component in which the compound (a) is supported on the support (c) and the solid catalyst component in which the compound (a) and the compound (b) are supported on the support (c) may be prepolymerized with an olefin, or a catalyst component may be further supported on the prepolymerized solid catalyst component.

In the method for producing the ethylene-α-olefin-non-conjugated polyene copolymer (A), the ethylene-α-olefin-non-conjugated polyene copolymer (A) can be produced by copolymerizing ethylene, an α-olefin having 4 to 20 carbon atoms, and a non-conjugated polyene in the presence of the above-mentioned catalyst for the ethylene-α-olefin-non-conjugated polyene copolymer.

The present invention can be carried out using either a liquid phase polymerization method such as solution (dissolution) polymerization or suspension polymerization, or a gas phase polymerization method.

Specific examples of inert hydrocarbon media used in liquid phase polymerization include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; aromatic hydrocarbons such as benzene, toluene, and xylene; and halogenated hydrocarbons such as ethylene chloride, chlorobenzene, and dichloromethane. These can be used alone or in combination of two or more. Olefins themselves can also be used as the solvent.

When ethylene or the like is polymerized using the above-mentioned copolymerization catalyst, the compound (a) is used in an amount of usually 10 ⁻¹² to 10 ⁻² mol, preferably 10 ⁻¹⁰ to 10 ⁻⁸ mol, per liter of reaction volume.

Compound (b-1) is used in an amount such that the molar ratio [(b-1)/M] of compound (b-1) to the total transition metal atoms (M) in compound (a) is usually 0.01 to 50,000, preferably 0.05 to 10,000. Compound (b-2) is used in an amount such that the molar ratio [(b-2)/M] of aluminum atoms in compound (b-2) to the total transition metal atoms (M) in compound (a) is usually 10 to 50,000, preferably 20 to 10,000. Compound (b-3) is used in an amount such that the molar ratio [(b-3)/M] of compound (b-3) to the transition metal atoms (M) in compound (a) is usually 1 to 20, preferably 1 to 15.

The polymerization temperature for ethylene and other polymers using such copolymer catalysts is usually in the range of -50 to +200°C, preferably 0 to +200°C, and more preferably +80 to +200°C. From the viewpoint of productivity, a higher temperature (+80°C or higher) is desirable, depending on the molecular weight and polymerization activity of the copolymer catalyst system used.

The polymerization pressure is usually between normal pressure and 10 MPa gauge pressure, preferably between normal pressure and 5 MPa gauge pressure, and the polymerization reaction can be carried out in any of batch, semi-continuous, and continuous systems. Furthermore, the polymerization can be carried out in two or more stages with different reaction conditions.

The molecular weight of the resulting ethylene polymer can be adjusted by making hydrogen present in the polymerization system or by changing the polymerization temperature. It can also be adjusted by the amount of compound (b) used. Specific examples include triisobutylaluminum, methylaluminoxane, and diethylzinc. When hydrogen is added, the appropriate amount is about 0.001 to 100 NL per kg of olefin.

<Ethylene copolymer composition for fuel cell gasket>
The ethylene copolymer composition for fuel cell gaskets of the present invention contains 100 to 20 parts by mass, preferably 95 to 50 parts by mass, of the ethylene/α-olefin/non-conjugated polyene copolymer (S) and 0 to 80 parts by mass, preferably 5 to 50 parts by mass, of the ethylene/α-olefin/non-conjugated polyene copolymer (A) (wherein the total of the copolymer (S) and the copolymer (A) is 100 parts by mass).

When the ethylene copolymer composition for fuel cell gaskets of the present invention is composed solely of the copolymer (S), it has good fluidity and a fast vulcanization rate (crosslinking rate), which allows the vulcanization time (crosslinking time) to be shortened, and the fuel cell gasket obtained by crosslinking the composition has good durability, such as compression set and heat aging resistance.

On the other hand, when the ethylene copolymer composition for fuel cell gaskets of the present invention contains the above-mentioned copolymer (A), the fluidity and vulcanization rate (crosslinking rate) are somewhat decreased, but the fuel cell gasket obtained by crosslinking the composition has better mechanical strength and low-temperature properties while maintaining the same durability.

The ethylene copolymer composition for fuel cell gaskets of the present invention may contain other polymers in addition to the copolymer (S) and the copolymer (A). Examples of other polymers that require crosslinking include crosslinkable rubbers such as natural rubber, isoprene rubber, butadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, acrylic rubber, silicone rubber, fluororubber, and urethane rubber. Examples of other polymers that do not require crosslinking include block copolymers of styrene and butadiene (SBS), styrene-based thermoplastic elastomers (TPS) such as polystyrene-poly(ethylene-butylene)-polystyrene (SEBS) and polystyrene-poly(ethylene-propylene)-polystyrene (SEPS), olefin-based 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). The other polymer can be blended in an amount of usually 100 parts by mass or less, preferably 80 parts by mass or less, per 100 parts by mass of the total amount of the ethylene-α-olefin-non-conjugated polyene copolymer (S) and the ethylene-α-olefin-non-conjugated polyene copolymer (A).

The ethylene copolymer composition for fuel cell gaskets of the present invention may contain other additives according to the purpose, such as at least one selected from a crosslinking aid, a vulcanization accelerator, a vulcanization aid, a softener, a reinforcing agent, an antiaging agent, an inorganic filler, a processing aid, an activator, a moisture absorbent, a heat stabilizer, a weather stabilizer, an antistatic agent, a colorant, a lubricant, a thickener, a foaming agent, and a foaming aid. In addition, each additive may be used alone or in combination of two or more kinds.

The ethylene copolymer composition for fuel cell gaskets of the present invention can be prepared by kneading the above-mentioned copolymer (S) and the above-mentioned copolymer (A) with other components that are blended as necessary at a desired temperature using a kneading machine such as a mixer, kneader, or roll.

Specifically, the copolymer (S) and the copolymer (A) and other components as required are kneaded at a predetermined temperature and time, for example, at 80 to 200°C for 3 to 30 minutes using a conventionally known kneading machine such as a mixer or kneader, and then other components used as required, such as a crosslinking agent, are added to the kneaded mixture obtained as required, and the mixture is kneaded using a roll at a predetermined temperature and time, for example, at a roll temperature of 30 to 80°C for 1 to 30 minutes, to prepare the ethylene copolymer composition for fuel cell gaskets of the present invention.

<Crosslinking Agent, Crosslinking Coagent, Vulcanization Accelerator, and Vulcanization Coagent>
Examples of the crosslinking agent include crosslinking agents generally used when crosslinking rubber, such as organic peroxides, phenolic resins, sulfur-based compounds, hydrosilicone-based compounds, amino resins, quinone or its derivatives, amine-based compounds, azo-based compounds, epoxy-based compounds, isocyanate-based compounds, etc. Among these, organic peroxides and sulfur-based compounds (hereinafter also referred to as "vulcanizing agents") are preferred.

Examples of organic peroxides include dicumyl peroxide (DCP), 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-butylperoxybenzoate, ert-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and tert-butylcumyl peroxide.

When an organic peroxide is used as a crosslinking agent, the amount of the organic peroxide in the ethylene copolymer composition for fuel cell gaskets is generally 0.1 to 20 parts by mass, preferably 0.2 to 15 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the total of the copolymer (S) and the copolymer (A) and other polymers (such as crosslinkable rubber) that require crosslinking and are added as necessary. When the amount of the organic peroxide is within the above range, the ethylene copolymer composition for fuel cell gaskets exhibits excellent crosslinking properties without blooming on the surface of the resulting fuel cell gasket, which is preferable.

When an organic peroxide is used as the crosslinking agent, it is preferable to use a crosslinking assistant in combination. Examples of crosslinking assistants include sulfur; quinone dioxime-based crosslinking assistants such as p-quinone dioxime; acrylic crosslinking assistants such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate; allyl crosslinking assistants such as diallyl phthalate and triallyl isocyanurate; maleimide-based crosslinking assistants; divinylbenzene; and metal oxides such as zinc oxide (e.g., ZnO#1 and zinc oxide type 2 (JIS standard (K-1410)), manufactured by Hakusui Tech Co., Ltd.), magnesium oxide, and activated zinc oxide (e.g., zinc oxide such as "META-Z102" (trade name; manufactured by Inoue Seki Kogyo Co., Ltd.)).

When a cross-linking aid is used, the amount of the cross-linking aid in the ethylene copolymer composition for fuel cell gaskets is usually 0.5 to 10 moles, preferably 0.5 to 7 moles, and more preferably 1 to 6 moles per mole of organic peroxide.

Examples of sulfur-based compounds (vulcanizing agents) include sulfur, sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram disulfide, and selenium dithiocarbamate.

When a sulfur-based compound is used as the crosslinking agent, the amount of the compound in the ethylene copolymer composition for fuel cell gaskets is usually 0.3 to 10 parts by mass, preferably 0.5 to 7.0 parts by mass, and more preferably 0.7 to 5.0 parts by mass, per 100 parts by mass of the total of the copolymer (S) and the polymer (A) and other polymers (such as crosslinkable rubber) that require crosslinking and are added as necessary. When the amount of the sulfur-based compound is within the above range, there is no blooming on the surface of the resulting fuel cell gasket, and the ethylene copolymer composition for fuel cell gaskets exhibits excellent crosslinking properties.

When a sulfur-based compound is used as the crosslinking agent, it is preferable to use a vulcanization accelerator in combination.
Examples of the vulcanization accelerator include N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, N,N'-diisopropyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole (e.g., Suncerer M (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), 2-(4-morpholinodithio)benzothiazole (e.g., Noccelaer MDB-P (trade name; manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-dinitrophenyl)mercaptobenzothiazole, Thiazole-based vulcanization accelerators such as ethyl-4-morpholinothio)benzothiazole and dibenzothiazyl disulfide (for example, Sancerer DM (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)); guanidine-based vulcanization accelerators such as diphenyl guanidine, triphenyl guanidine and diorthotolyl guanidine; aldehyde amine-based vulcanization accelerators such as acetaldehyde-aniline condensate and butyraldehyde-aniline condensate; imidazoline-based vulcanization accelerators such as 2-mercaptoimidazoline; tetramethylthiuram monosulfide (for example, Sancerer DM (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)); thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (e.g., Sancerer TS (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), tetramethylthiuram disulfide (e.g., Sancerer TT (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), tetraethylthiuram disulfide (e.g., Sancerer TET (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), tetrabutylthiuram disulfide (e.g., Sancerer TBT (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)) and dipentamethylenethiuram tetrasulfide (e.g., Sancerer TRA (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)); zinc dimethyldithiocarbamate, diethyldithio Examples of the vulcanization accelerator include dithioacid salt vulcanization accelerators such as zinc carbamate, zinc dibutyldithiocarbamate (for example, Sanseller PZ, Sanseller BZ, and Sanseller EZ (trade names; manufactured by Sanshin Chemical Industry Co., Ltd.)) and tellurium diethyldithiocarbamate; thiourea vulcanization accelerators such as ethylenethiourea (for example, Sanseller BUR (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.), Sanseller 22-C (trade name; manufactured by Sanshin Chemical Industry Co., Ltd.)), N,N'-diethylthiourea, and N,N'-dibutylthiourea; and xanthate vulcanization accelerators such as zinc dibutylxatogenate.

When a vulcanization accelerator is used, the blending amount of the vulcanization accelerator in the ethylene copolymer composition for fuel cell gasket is generally 0.1 to 20 parts by mass, preferably 0.2 to 15 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the total of the above-mentioned copolymer (S) and the above-mentioned copolymer (A) and other polymers (such as crosslinkable rubber) that require crosslinking and are blended as necessary. When the blending amount of the vulcanization accelerator is within the above range, the ethylene copolymer composition for fuel cell gasket exhibits excellent crosslinking properties without blooming on the surface of the obtained fuel cell gasket.

When a sulfur-based compound is used as the crosslinking agent, a vulcanization aid can be used in combination.
Examples of the vulcanization aid include zinc oxide (e.g., ZnO#1 and zinc oxide type 2, manufactured by Hakusui Tech Co., Ltd.), magnesium oxide, and activated zinc oxide (e.g., zinc oxide such as "META-Z102" (trade name; manufactured by Inoue Seki Kogyo Co., Ltd.)).

When a vulcanization aid is used, the amount of vulcanization aid blended in the ethylene copolymer composition for fuel cell gaskets is usually 1 to 20 parts by mass per 100 parts by mass of the total of the copolymer (S) and the copolymer (A) and other polymers that require crosslinking (such as crosslinkable rubber) that are blended as necessary.

<Softener>
Examples of softeners include petroleum-based softeners such as process oil, lubricating oil, paraffin oil, liquid paraffin, petroleum asphalt, and Vaseline; coal tar-based softeners such as coal tar; fatty oil-based softeners 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 derivatives thereof; synthetic polymeric substances such as terpene resins, petroleum resins, and coumarone-indene resins; ester-based softeners such as dioctyl phthalate and dioctyl adipate; and other softeners such as microcrystalline wax, liquid polybutadiene, modified liquid polybutadiene, hydrocarbon-based synthetic lubricating oils, tall oil, and sub (factice). Of these, petroleum-based softeners are preferred, and process oil is particularly preferred.

When the ethylene copolymer composition for fuel cell gaskets contains a softener, the amount of the softener is generally 0 to 100 parts by mass, preferably 0 to 80 parts by mass, per 100 parts by mass of the total of the copolymer (S) and the copolymer (A) and other polymer components (elastomer, crosslinkable rubber, etc.) that are blended as necessary.

<Reinforcing agent>
Examples of reinforcing agents include carbon black, carbon black surface-treated with a silane coupling agent, silica, calcium carbonate, activated calcium carbonate, finely divided talc, and differential silicic acid.

When the ethylene copolymer composition for fuel cell gaskets contains a reinforcing agent, the amount of the reinforcing agent is generally 5 to 150 parts by mass, preferably 5 to 100 parts by mass, per 100 parts by mass of the total of the copolymer (S) and the copolymer (A) and other polymers (elastomers, crosslinkable rubbers, etc.) that are blended as necessary.

<Anti-aging agent (stabilizer)>
By blending an antioxidant (stabilizer) with the ethylene copolymer composition for fuel cell gaskets of the present invention, the life of the fuel cell gasket formed therefrom can be extended. Examples of such antioxidants include conventionally known antioxidants, such as amine-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants.

Examples of antioxidants include aromatic secondary amine antioxidants such as phenylbutylamine and N,N-di-2-naphthyl-p-phenylenediamine; phenolic antioxidants such as dibutylhydroxytoluene and tetrakis[methylene(3,5-di-t-butyl-4-hydroxy)hydrocinnamate]methane; thioether antioxidants such as bis[2-methyl-4-(3-n-alkylthiopropionyloxy)-5-t-butylphenyl]sulfide; dithiocarbamate antioxidants such as nickel dibutyldithiocarbamate; and sulfur-based antioxidants such as 2-mercaptobenzoylimidazole, 2-mercaptobenzimidazole, zinc salt of 2-mercaptobenzimidazole, dilaurylthiodipropionate, and distearylthiodipropionate.

When the ethylene copolymer composition for fuel cell gaskets contains an antioxidant, the amount of the antioxidant is usually 0.3 to 10 parts by mass, preferably 0.5 to 7.0 parts by mass, per 100 parts by mass of the total of the copolymer (S) and the copolymer (A) and other polymers (elastomers, crosslinkable rubbers, etc.) that are blended as necessary. When the amount of the antioxidant is within the above range, there is no bloom on the surface of the resulting fuel cell gasket, and furthermore, the occurrence of vulcanization inhibition can be suppressed.

<Inorganic fillers>
Examples of inorganic fillers include light calcium carbonate, heavy calcium carbonate, talc, clay, and the like. Of these, heavy calcium carbonate such as "Whiten SB" (product name; Shiraishi Calcium Co., Ltd.) is preferred.

When the ethylene copolymer composition for fuel cell gaskets contains an inorganic filler, the amount of inorganic filler is usually 2 to 50 parts by mass, preferably 5 to 50 parts by mass, per 100 parts by mass of the total of the copolymer (S) and the copolymer (A) and other polymers (elastomers, crosslinkable rubbers, etc.) that are blended as necessary. When the amount of inorganic filler is within the above range, the ethylene copolymer composition for fuel cell gaskets has excellent kneading processability, and a fuel cell gasket with excellent mechanical properties can be obtained.

<Processing aids>
As the processing aid, for example, a wide variety of processing aids that are generally compounded with rubber can be used.

Specific examples of 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 esters. Of these, stearic acid is preferred.

When the ethylene copolymer composition for fuel cell gaskets contains a processing aid, the amount of the processing aid is usually 10 parts by mass or less, preferably 8.0 parts by mass or less, per 100 parts by mass of the total of the copolymer (S) and the copolymer (A) and other polymers (elastomers, crosslinkable rubbers, etc.) that are blended as necessary.

<Activator>
Examples of the activator include amines such as di-n-butylamine, dicyclohexylamine, and monoethanolamine; activators such as diethylene glycol, polyethylene glycol, lecithin, triaryl methylate, and zinc compounds of aliphatic or aromatic carboxylic acids; zinc peroxide preparations; octadecyltrimethylammonium bromide, synthetic hydrotalcite, and special quaternary ammonium compounds.

When the ethylene copolymer composition for fuel cell gaskets contains an activator, the amount of the activator is usually 0.2 to 10 parts by mass, preferably 0.3 to 5 parts by mass, per 100 parts by mass of the total of the copolymer (S) and the copolymer (A) and other polymers (elastomers, crosslinkable rubbers, etc.) that are blended as necessary.

Moisture absorbent
Examples of moisture absorbents include calcium oxide, silica gel, sodium sulfate, molecular sieves, zeolite, and white carbon.

When the ethylene copolymer composition for fuel cell gaskets contains a moisture absorbent, the amount of the moisture absorbent is usually 0.5 to 15 parts by mass, preferably 1.0 to 12 parts by mass, per 100 parts by mass of the total of the copolymer (S) and the copolymer (A) and other polymers (elastomers, crosslinkable rubbers, etc.) that are blended as necessary.

<Foaming agent and foaming assistant>
The seal packing formed using the ethylene copolymer composition for a fuel cell gasket of the present invention may be a non-foamed product or a foamed product. When the fuel cell gasket is a foamed product, the ethylene copolymer composition for a fuel cell gasket preferably contains a foaming agent.

As the foaming agent, any of commercially available foaming agents can be suitably used. Examples of such foaming agents 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; sulfonyl hydrazide compounds such as benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, and p,p'-oxybis(benzenesulfonyl hydrazide)diphenylsulfone-3,3'-disulfonyl hydrazide; and azide compounds such as calcium azide, 4,4'-diphenyldisulfonyl azide, and paratoluenemalonyl azide. Among these, azo compounds, sulfonyl hydrazide compounds, and azide compounds are preferably used.

When the ethylene copolymer composition for fuel cell gaskets contains a foaming agent, the amount of foaming agent is appropriately selected depending on the performance required for the fuel cell gasket produced from the ethylene copolymer composition for fuel cell gaskets, but is usually used in a ratio of 0.1 to 30 parts by mass, preferably 0.2 to 20 parts by mass, per 100 parts by mass of the total of the copolymer (S) and the copolymer (A) and other polymers (elastomers, crosslinkable rubbers, etc.) that are blended as necessary.

If necessary, a foaming assistant may be used in combination with the foaming agent. The addition of a foaming assistant is effective in adjusting the decomposition temperature of the foaming agent and uniformizing the bubbles. Specific examples of foaming assistants include organic acids such as salicylic acid, phthalic acid, stearic acid, and oxalic acid, as well as urea and its derivatives.

When the ethylene copolymer composition for fuel cell gaskets contains a foaming aid, the foaming aid is usually used in an amount of 1 to 100 parts by mass, preferably 2 to 80 parts by mass, per 100 parts by mass of the foaming agent.

By using the ethylene copolymer composition for fuel cell gaskets of the present invention, it is possible to obtain a fuel cell gasket that is superior in low-temperature flexibility compared to when conventional EPDM is used, and it is possible to obtain a fuel cell gasket that is superior in cold resistance compared to when silicone rubber is used.

<Fuel cell gasket>
The fuel cell gasket of the present invention is formed from the above-mentioned ethylene copolymer composition for a fuel cell gasket.

As a method for producing a fuel cell gasket from the ethylene copolymer composition for fuel cell gaskets of the present invention, for example, a method can be mentioned in which the ethylene copolymer composition for fuel cell gaskets is molded into a desired fuel cell gasket shape, and the composition is crosslinked simultaneously with or after this molding.

Examples of methods for crosslinking include a method in which a composition containing a crosslinking agent is used as the ethylene copolymer composition for fuel cell gaskets and crosslinked by heating, and a method in which the ethylene copolymer composition for fuel cell gaskets is crosslinked by irradiating it with an electron beam.

That is, the fuel cell gasket of the present invention can be prepared by molding the ethylene copolymer composition for fuel cell gaskets into the intended shape using a molding machine such as an extrusion molding machine, a calendar roll, a press, an injection molding machine, or a transfer molding machine, and crosslinking the composition by heating at 120 to 270°C for 1 to 30 minutes at the same time as molding, or by introducing the molded product into a vulcanization tank and heating the product at 120 to 270°C for 1 to 30 minutes, or by irradiating the product with electron beams.

Crosslinking may be performed using a mold, or without a mold. When a mold is not used, the molding and crosslinking steps are usually performed continuously. Heating methods in the vulcanization tank can include hot air, a glass bead fluidized bed, UHF (ultra-high frequency electromagnetic waves), steam, etc.

When an electron beam is used as the cross-linking method without using a cross-linking agent, the ethylene copolymer composition for fuel cell gaskets molded into a predetermined shape is irradiated with an electron beam having an energy of typically 0.1 to 10 MeV, preferably 0.3 to 2 MeV, so that the absorbed dose is typically 0.5 to 35 Mrad, preferably 0.5 to 10 Mrad.

The fuel cell gasket of the present invention is a fuel cell gasket used in a hydrogen line. At hydrogen stations that supply hydrogen to fuel cell vehicles and the like, there are many hydrogen lines through which hydrogen passes. The fuel cell gasket of the present invention is used as a fuel cell gasket for use in such hydrogen lines.

Hydrogen stations store large amounts of hydrogen, so it must be stored in a compressor at high pressure. In addition, when hydrogen is supplied from a hydrogen station, it must be sent out at high pressure and high speed, which causes the temperature of the hydrogen to rise. In order to prevent the temperature inside the hydrogen tank of a fuel cell vehicle or the like from rising too high, hydrogen stations must store hydrogen at low temperatures, for example, around -40°C. For this reason, fuel cell gaskets used in hydrogen lines are required to have sealing properties at low temperatures. The fuel cell gasket of the present invention combines low-temperature properties with mechanical strength (strength and elongation), making it suitable for use in hydrogen lines.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" refers to "parts by mass".
In the examples and comparative examples, the following copolymers were used.

[Ethylene-α-olefin-non-conjugated polyene copolymer (S)]
Production of Copolymer (S-1) <Production of Ethylene-Propylene-VNB Copolymer>
In the method for producing an ethylene-propylene-VNB copolymer described in Example 1 ([0386] to [0391]) of WO 2019/180802, the amount of hydrogen fed was adjusted to produce the ethylene-propylene-VNB copolymer (S-1) shown in Table 1 below.

<Molar amounts of structural units derived from ethylene, structural units derived from α-olefins, and structural units derived from non-conjugated polyenes>
The molar amount was determined by intensity measurement using ^{a 1} H-NMR spectrometer. Details of the measurement conditions are described in WO 2015/122415.

<Mooney Viscosity>
The Mooney viscosity (ML(1+4) 100° C.) was measured using a Mooney viscometer (Shimadzu Corporation, SMV202 type) in accordance with JIS K6300 (1994).

<B value>
Using o-dichlorobenzene-d4/benzene-d6 (4/1 [v/v]) as the measurement solvent, ¹³ C-NMR spectrum (100 MHz, JEOL ECX400P) was measured at a measurement temperature of 120° C., and calculation was made based on the following formula (i).
B value = ([EX]+2[Y])/[2×[E]×([X]+[Y])]...(i)
[Here, [E], [X] and [Y] respectively represent the molar fractions of structural units derived from ethylene [A1], an α-olefin having 3 to 20 carbon atoms [A2] and a non-conjugated polyene [A3], and [EX] represents the ethylene [A1]-α-olefin having 3 to 20 carbon atoms [A2] dyad chain fraction.]

As the ethylene/α-olefin/non-conjugated polyene copolymer (A), the following ethylene/α-olefin/non-conjugated polyene copolymer [copolymer (A-1)] was used.
According to the description of [Synthesis Example C1] of WO 2015/122415, an ethylene/1-butene/5-ethylidene-2-norbornene (ENB) copolymer having the following physical properties was obtained. Hereinafter, this is referred to as "copolymer (A-1)".

The constitution and physical properties of the copolymer (A-1) are as follows:
Structural units derived from ethylene: 67.7 mol%
Structural units derived from 1-butene: 30.0 mol%
Structural units derived from ENB: 2.3 mol%
Mooney Viscosity ML(1+4) 100℃: 30
B value: 1.3

[Example 1]
Ethylene copolymer composition for fuel cell gasket
Using a MIXTRON BB MIXER (manufactured by Kobe Steel, Ltd., BB-4 type, volume 2.95 L, rotor 4WH), 25 parts of copolymer (S-1) and 75 parts of copolymer (A-1) [copolymer (S-1) + copolymer (A-1) = 100 parts] were mixed with 5 parts of active zinc oxide (trade name META Z-102, manufactured by Inoue Lime Industry Co., Ltd.), 1 part of stearic acid, 50 parts of carbon black "Asahi #60UG" (trade name; manufactured by Asahi Carbon Co., Ltd.), 6 parts of Sandant MB (2-mercaptobenzimidazole, manufactured by Sanshin Chemical Industry Co., Ltd.) as an antiaging agent, Irganox 1010 (dibutylhydroxytoluene, tetrakis [methylene (3,5-di-t-butyl-4-hydroxy) hydrocinnamate] methane, BASF: 3 parts of the above-mentioned polyurethane foam were mixed and 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.
Next, after confirming that the temperature of Compound 1 had reached 40°C, a 6-inch roll was used to add and knead Compound 1 with 7.3 parts of 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane (product name: Perhexa 25B, manufactured by Nippon Oil & Fats Co., Ltd.) and Kayacumyl D-40C (dicumyl peroxide 40% by mass, manufactured by Kayaku Akzo Co., Ltd.) as a crosslinking agent (vulcanizing agent), to obtain Compound 2.

The kneading conditions were roll temperature front roll/rear roll = 50°C/50°C, roll peripheral speed front roll/rear roll = 18 rpm/15 rpm, roll gap 3 mm, and kneading time 8 minutes to obtain compound 2.

[Unvulcanized physical property test 1: Mooney viscosity]
The Mooney viscosity ML ₍₁₊₄₎ 100°C of Blend 2 was measured using a Mooney viscometer (Shimadzu Corporation, Model SMV202) in accordance with JIS K6300 (1994).

[Unvulcanized Physical Properties Test 2: Evaluation of Vulcanized Properties]
The vulcanization rate (tC90): 180°C of Compound 2 was measured using a vulcanization measuring device: MDR2000 (manufactured by ALPHA TECHNOLOGIES) as follows.

The torque change obtained under conditions of constant temperature and constant shear rate was measured.
The time required to reach 90% of the difference between the maximum torque (S'Max) and the minimum torque (S'Min) was defined as TC90 (min). The measurement conditions were a temperature of 180°C and a time of 15 minutes. The smaller the TC90, the faster the vulcanization rate (crosslinking rate).

Evaluation of vulcanized (crosslinked) products
Compound 2 was crosslinked at 180° C. for 10 minutes using a press molding machine to prepare a sheet (vulcanizate) having a thickness of 2 mm.

The obtained sheet was subjected to a hardness test, a tensile test, a heat aging resistance test, and a TR test by the following methods.
Compound 2 was vulcanized at 180°C for 13 minutes using a press molding machine equipped with a cylindrical mold to prepare a right cylindrical test piece having a thickness of 12.7 mm and a diameter of 29 mm, and a test piece (vulcanizate) for compression set (CS) test was obtained.
The compression set (CS) test specimen thus obtained was used to evaluate the compression set by the following method.
The results are shown in Table 2.

[Hardness test: Hardness (Durometer-A)]
The hardness of the sheet was measured in accordance with the description of "Hardness test" in item 7 of JIS K7312 (1996) "Physical test methods for thermosetting polyurethane elastomer moldings" and the description of test type A of "Durometer hardness test" in item 6 of JIS K6253 (2006) "Vulcanized rubber and thermoplastic rubber -- Determination of hardness".

[Tensile test: modulus, tensile stress at break, tensile elongation at break]
The modulus, tensile stress at break, and tensile elongation at break of the sheet were measured by the following methods.
The sheet was punched out to prepare No. 3 dumbbell test pieces described in JIS K6251 (1993). Using these test pieces, a tensile test was carried out according to the method specified in JIS K6251, section 3, at a measurement temperature of 25°C and a tensile speed of 500 mm/min, and the tensile stress when the elongation rate was 25% (25% modulus (M25)), the tensile stress when the elongation rate was 50% (50% modulus (M50)), the tensile stress when the elongation rate was 100% (100% modulus (M100)), the tensile stress at break (TB) and the tensile elongation at break (EB) were measured.

[Heat aging resistance test]
The sheet was subjected to a heat aging test in which the sheet was held at 180° C. for 168 hours in accordance with JIS K6257. The hardness, tensile stress at break, and tensile elongation at break of the sheet after the heat aging test were measured in the same manner as in the above items [Hardness (Durometer-A)] and [Modulus, tensile stress at break, and tensile elongation at break].

AH (Duro-A) was calculated from the difference in hardness before and after the heat aging test, and Ac(TB) and Ac(EB) were calculated as the rate of change after the test from the values before the heat aging test based on the tensile stress at break (TB) and tensile elongation at break (EB) before and after the heat aging test, respectively.

[TR test (low temperature elastic recovery test)]
The sheet was subjected to a TR test (low temperature elastic recovery test) in accordance with JIS K6261 to measure cold resistance.

In this test, the stretched sheet is frozen and the temperature is continuously raised to measure the recovery of the stretched sheet. (The temperatures at which the length of the test piece shrinks (recovers) by 10% and 65% due to heating are designated TR-10 and TR-65, respectively.) The lower the TR-10 (unit: °C), the better the cold resistance.

[Examples 2 to 4]
The same procedure as in Example 1 was repeated, except that the amounts of copolymer (S-1) and copolymer (A-1) used in Example 1 were changed to the amounts shown in Table ◯.
The results are shown in Table 2.

[Comparative Example 1]
The same procedure as in Example 1 was repeated, except that the mixture of copolymer (S-1) and copolymer (A-1) used in Example 1 was replaced by copolymer (A-1) alone.
The results are shown in Table 2.

As is clear from Table 2, the composition consisting of 100 parts by mass of copolymer (S-1) (Example 4) has a lower Mooney viscosity, better fluidity, and a faster vulcanization rate than the composition consisting of 100 parts by mass of copolymer (A-1) (Comparative Example 1), and the resulting vulcanizate has better durability, such as heat aging resistance and compression set.

The compositions (Examples 1 to 3) containing copolymer (A-1) have slightly lower fluidity and vulcanization speed than Example 4, but are superior in fluidity and vulcanization speed to Comparative Example 1. Furthermore, the resulting vulcanizates have better mechanical strength and low-temperature properties than Example 4 while maintaining the same durability.

The compositions obtained in Examples 1 and 2 have a good balance between fluidity, vulcanization speed, and durability, mechanical strength, and low-temperature properties of the resulting vulcanizates.

Claims (6)

100 to 20 parts by mass of an ethylene/α-olefin/non-conjugated polyene copolymer (S) having structural units derived from ethylene (A), an α-olefin (B) having 3 to 20 carbon atoms, and a non-conjugated polyene (C) containing in the molecule a total of two or more partial structures selected from the group consisting of the following general formulas (I) and (II), and satisfying the following requirements (i) to (vi);
An ethylene copolymer composition for a fuel cell gasket, comprising: 0 to 80 parts by mass of an ethylene/α-olefin/non-conjugated polyene copolymer (A) having 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], and satisfying the following requirements (1) to (3) (wherein the total of the copolymer (S) and the copolymer (A) is 100 parts by mass):
[Requirements for ethylene-α-olefin-non-conjugated polyene copolymer (S)]
(i) the molar ratio of the structural units derived from ethylene (A) to the structural units derived from an α-olefin (B) [(A)/(B)] is 40/60 to 99.9/0.1;
(ii) the mass fraction of the constitutional unit derived from the non-conjugated polyene (C) is 0.07% by mass to 10% by mass in 100% by mass of the copolymer (S);
(iii) the weight average molecular weight (Mw) of the copolymer (S), the weight fraction of the constitutional unit derived from the non-conjugated polyene (C) (weight fraction (wt%) of (C)), and the molecular weight of the non-conjugated polyene (C) (molecular weight of (C)) satisfy the following formula (1);
4.5≦Mw×mass fraction of (C)/100/molecular weight of (C)≦40...Equation (1)
(iv) the ratio P(η*(ω=0.1)/η*(ω=100)) of the complex viscosity η*(ω=0.1) (Pa sec) at a frequency ω=0.1 rad/s to the complex viscosity η*(ω=100) (Pa sec) at a frequency ω=100 rad/s, which are obtained by linear viscoelasticity measurement (190° C.) using a rheometer, the intrinsic viscosity [η], and the mass fraction of the constituent unit derived from the non-conjugated polyene (C) (mass fraction of (C)) satisfy the following formula (2);
P/([η] ^2.9 )≦mass fraction of (C)×6 (2)
(v) the ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (molecular weight distribution; Mw/Mn) measured by gel permeation chromatography (GPC) is in the range of 4 to 80;
(vi) The number average molecular weight (Mn) is 30,000 or less.
[Requirements for the ethylene/α-olefin/non-conjugated polyene copolymer (A)]
(1) the molar ratio [[A1]/[A2]] of the structural unit derived from ethylene [A1] to the structural unit derived from an α-olefin [A2] having 4 to 20 carbon atoms is 40/60 to 90/10;
(2) the content of the structural unit derived from the non-conjugated polyene [A3] is 0.1 to 6.0 mol % relative to 100 mol % of the total of the structural units derived from [A1], [A2] and [A3];
(3) The B value represented by the following formula (i) is 1.20 or more.
B value = ([EX]+2[Y])/[2×[E]×([X]+[Y])]...(i)
[Here, [E], [X] and [Y] respectively represent the molar fractions of structural units derived from ethylene [A1], an α-olefin having 4 to 20 carbon atoms [A2] and a non-conjugated polyene [A3], and [EX] represents the ethylene [A1]-α-olefin having 4 to 20 carbon atoms [A2] dyad chain fraction.] 2. The ethylene copolymer composition for a fuel cell gasket according to claim 1, wherein the structural unit derived from the α-olefin [A2] having 4 to 20 carbon atoms in the copolymer (A) contains a structural unit derived from 1-butene. 3. The ethylene copolymer composition for fuel cell gaskets according to claim 1, wherein the non-conjugated polyene (C) in the copolymer (S) contains a structural unit derived from 5-vinyl-2-norbornene. The ethylene copolymer composition for a fuel cell gasket according to any one of claims 1 to 3, further comprising 1 to 30 parts by mass of an organic peroxide per 100 parts by mass of the total of the copolymer (S) and the copolymer (A). A gasket for a fuel cell obtained by using the ethylene copolymer composition for a fuel cell gasket according to any one of claims 1 to 4. The fuel cell gasket according to claim 5, wherein the fuel cell gasket is a cross-linked body.