Description
Title of Invention: RAILROAD RAIL TRACK PAD AND CROSSLINKED
FOAM
Technical Field
[0001]
The present invention relates to a railroad rail track pad composed of a
crosslinked material or a crosslinked foam, and the crosslinked foam per se.
More particularly, the present invention relates to a railroad rail track pad and a
crosslinked foam obtained from a rubber composition exhibiting sufficiently
high foaming properties. Further particularly, the present invention relates to
a railroad rail track pad composed of a crosslinked material or a crosslinked
foam made of a low specific gravity rubber molded product of which physical
properties (including weather resistance), such as a moderate elastic modulus,
high tensile strength and elongation, and small compression set, are required
and which further also has excellent processability, and the crosslinked form.
Background Art
[0002]
As a vibration isolator for reducing vibration and noise that occur
during the running of a train, a railroad pad is used in the track (rail) of a
railroad. This railroad pad encompasses a resilient sleeper pad inserted
between a rail and a tie, a tie pad laid under a tie, a track slab vibration isolator
laid under a slab of a slab track, and the like.
[0003]
Conventionally, as a material used for a railroad pad, an SBR-based

non-foamed rubber has been used. In addition, the use of a foamed
polyurethane elastomer is also proposed (Patent Document 1). However,
when an SBR-based non-foamed rubber or a foamed polyurethane elastomer
is used for a track pad, the weather resistance tends to be poor.
[0004]
On the other hand, an ethylene-propylene-diene copolymer rubber
(EPDM) has no double bond in the main chain of its molecular structure and,
therefore, exhibits excellent heat aging resistance, weather resistance, and
ozone resistance as compared with general-purpose conjugated diene rubber
(Patent Document 2). However, when such an EPDM is used for a track pad,
the weather resistance is good because EPDM contains no diene in the main
chain, but foaming properties and a balance of the physical properties are
insufficient.
[0005]
Patent Document 3 proposes the provision of a rubber composition
exhibiting flame retardancy and having sufficient foaming properties, and
proposes a rubber molded product having excellent low specific gravity and
surface smoothness obtained by crosslinking and foaming the rubber
composition.
Prior art documents
Patent Document
[0006]
Patent Document 1: JP-2007-284625 A
Patent Document 2: U.S. Patent No. 5738279
Patent Document 3: JP-2011-195656 A

Summary of Invention
Problems to be Solved by the Invention
[0007]
For a railroad rail track pad composition, physical properties (including
weather resistance), such as a moderate elastic modulus, high tensile strength
and elongation, and small compression set, are required, and further also
excellent processability is desired. It is an object of the present invention to
provide a railroad rail track pad composed of a crosslinked material or a
crosslinked foam having such physical properties and moreover also having
excellent processability, and a crosslinked foam suitable for an application for
this railroad rail track pad.
Means for Solving the Problems
[0008]
The present inventors have studied diligently over and over in order to
achieve the above object, and, as a result, found that using a particular
ethylene-a-olefin-non-conjugated diene random copolymer is very suitable for
railroad rail track pad applications, leading to the completion of the present
invention.
[0009]
Specifically, the present invention relates to a railroad rail track pad
obtained by crosslinking a composition including an
ethylene-a-olefin-non-conjugated polyene random copolymer including
structural units derived from ethylene [A], an a-olefin [B] having 3 to 20 carbon
atoms, a non-conjugated polyene [C-1], in which only one partial structure
represented by the following general formula (I) or (II) is presented in one

molecule,
[0010]
[Formula 1]

with the proviso that (!) is a partial structure of a cyclic olefin,
[0011]
[Formula 2]

[0012]
and a non-conjugated polyene [C-2], in which two or more partial structures
selected from a group consisting of the formula (I) and (II) are presented in
total in one molecule, wherein the copolymer satisfies conditions of the
following (1)to(6):
[0013]
(1) the structural units derived from the a-olefin [B] having 3 to 20 carbon
atoms constitute 10 to 50 mole% in 100 mole% of the total structural units,
(2) a sum of the mole% of the structural units derived from the
non-conjugated polyene [C-1] and the mole% of the structural units derived
from the non-conjugated polyene [C-2] is 1.0 to 6.0 mole%,
(3) a ratio of [C-1]/[C-2] in the mole% of the structural unit derived from the
non-conjugated polyene [C-1] to the mole% of the structural unit derived from
the non-conjugated polyene [C-2] is 75/25 to 99.5/0.5,

(4) Mooney viscosity measured at 100°C as [ML1+4 (100°C)] is 10 to 90,
(5) an apparent iodine value (I V) of the structural unit derived from the
non-conjugated polyene [C-2] is 0.1 to 3.0 g/100g, and
(6) the following expression (i) is satisfied:
[0014]
50 > activation energy (Ea) of fluidization [kJ/mol] >35 ••• (i).
Further, the present invention relates to a crosslinked foam obtained by
crosslinking and foaming a composition containing an
ethylene-a-olefin-non-conjugated polyene random copolymer, wherein
(a) specific gravity of the crosslinked foam is 0.75 or less, and
(b) an elastic modulus of the crosslinked foam is 3.0 N/mm2 or more.
[0015]
In addition, the present invention relates to a crosslinked foam
obtained by crosslinking and foaming a composition containing an
ethylene-a-olefin-non-conjugated polyene random copolymer, wherein
(a) specific gravity of the crosslinked foam is 0.75 or less, and
(c) an average value of diameters of voids from a maximum diameter
void to a 10th largest diameter void among voids observed in a fixed area (2.2
cm2) of a cross section of a molded product is 80 µm or less.
Advantages of the Invention
[0016]
According to the present invention, it is possible to provide a railroad
rail track pad composed of a crosslinked material or a crosslinked foam having
required physical properties (including weather resistance), such as a

moderate elastic modulus, high tensile strength and elongation, and small
compression set, and moreover also having excellent processability, and a
crosslinked foam suitable for an application for this railroad rail track pad.
Embodiments for Carrying Out the Invention
[0017]
A composition used for a railroad rail track pad according to the
present invention will be specifically described below.
[0018]

A copolymer used in the present invention is an
ethylene-a-olefin-non-conjugated polyene random copolymer including
structural units derived from ethylene [A], an a-olefin [B] having 3 to 20 carbon
atoms, a non-conjugated polyene [C-1], in which only one partial structure
represented by the above-described general formula (I) or (II) is presented in
one molecule, and a non-conjugated polyene [C-2], in which two or more
partial structures selected from a group consisting of the formula (I) and (II) are
presented in total in one molecule, wherein the copolymer satisfies the
conditions of the above-described (1) to (6). In the present specification, the
above-described (1) to (6) may be referred to as requirements (1) to (6),
respectively.
[0019]

Specific examples of the above-described a-olefin [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 them, in particular,
α-olefins having 3 to 8 carbon atoms, e.g., propylene, 1-butene, 1-hexane, and
1-octene, are preferable. Such a-olefins are favorable because the raw
material costs are relatively low and the resulting copolymers exhibit excellent
mechanical properties.
[0020]
In this regard, the copolymer used in the present invention includes
structural units derived from at least one type of the α-olefin [B] having 3 to 20
carbon atoms and may include structural units derived from at least two types
of the a-olefin [B] having 3 to 20 carbon atoms.
[0021]

Examples of the above-described non-conjugated polyene [C-1], in
which only one partial structure represented by the above-described general
formula (I) or (II) is presented in one molecule, do not include chain polyenes,
in which both terminals are vinyl groups (CH2=CH-). Examples of component
[C-1] include aliphatic polyenes and alicyclic polyenes, as described below.
[0022]
Specific examples of the above-described aliphatic polyenes include
1,4-hexadiene, 1,5-heptadiene, 1,6-octadiene, 1,7-nonadiene, 1,8-decadiene,
1,12-tetradecadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene,
5-methyl-1,4-hexadiene, 4-ethyl-1,4-hexadiene, 3,3-dimethyl-1,4-hexadiene,
5-methyl-1,4-heptadiene, 5-ethyl-1,4-heptadiene, 5-methyl-1,5-heptadiene,
6-methyl-1,5-heptadiene, 5-ethyl-1,5-heptadiene, 4-methyl-1,4-octadiene,
5-methyl-1,4-octadiene, 4-ethyl-1,4-octadiene, 5-ethyl-1,4-octadiene,
5-methyl-1,5-octadiene, 6-methyl-1,5-octadiene, 5-ethyl-1,5-octadiene,

6-ethyl-1,5-octadiene, 6-methyl-1,6-octadiene, 7-methyl-1,6-octadiene,
6-ethyl-1,6-octadiene, 6-propyl-1,6-octadiene, 6-butyl-1,6-octadiene,
7-methyl-1,6-octadiene, 4-methyl-1,4-nonadiene, 5-methyl-1,4-nonadiene,
4-ethyl-1,4-nonadiene, 5-ethyl-1,4-nonadiene, 5-methyl-1,5-nonadiene,
6-methyl-1,5-nonadiene, 5-ethyl-1,5-nonadiene, 6-ethyl-1,5-nonadiene,
6-methyl-1,6-nonadiene, 7-methyl-1,6-nonadiene, 6-ethyl-1,6-nonadiene,
7-ethyl-1,6-nonadiene, 7-methyl-1,7-nonadiene, 8-methyl-1,7-nonadiene,
7-ethyl-1,7-nonadiene, 5-methyl-1,4-decadiene, 5-ethyl-1,4-decadiene,
5-methyl-1,5-decadiene, 6-methyl-1,5-decadiene, 5-ethyl-1,5-decadiene,
6-ethyl-1,5-decadiene, 6-methyl-1,6-decadiene, 6-ethyl-1,6-decadiene,
7-methyl-1,6-decadiene, 7-ethyl-1,6-decadiene, 7-methyl-1,7-decadiene,
8-methyl-1,7-decadiene, 7-ethyl-1,7-decadiene, 8-ethyl-1,7-decadiene,
8-methyl-1,8-decadiene, 9-methyl-1,8-decadiene, 8-ethyl-1,8-decadiene,
6-methyl-1,6-undecadiene, and 9-methyl-1,8-undecadiene. In the present
invention, at least one type of these aliphatic polyenes can be used alone or in
combination. Preferably, 7-methyl-1,6-octadiene and the like are used.
[0023]
Examples of the above-described alicyclic polyenes include polyenes
composed of an alicyclic portion having one carbon-carbon double bond
(unsaturated bond) and a chain portion (e.g., ethylidene and propylidene)
bonded to a carbon atom constituting the alicyclic portion by a carbon-carbon
double bond. Specific examples include 5-ethylidene-2-norbornene (ENB),
5-propylidene-2-norbornene, and 5-butylidene-2-norbornene. Among them,
5-ethylidene-2-norbornene (ENB) is preferable. Examples of other alicyclic
polyenes include 2-methyl-2,5-norbomadiene and 2-ethyl-2,5-norbornadiene.
[0024]

In this regard, the copolymer used in the present invention includes at
least one type of structural units derived from the component [C-1] and may
include at least two types of structural units derived from the component [C-1].
[0025]

Examples of the above-described non-conjugated polyene [C-2], in
which two or more partial structures selected from a group consisting of the
formula (I) and (II) are presented in total in one molecule, include alicyclic
polyenes composed of an alicyclic portion having one carbon-carbon double
bond (unsaturated bond) and a chain portion that bonds to a carbon atom
constituting the alicyclic portion and contains a vinyl group, and aliphatic
polyenes, in which both terminals are vinyl groups. Specific examples include
5-alkenyl-2-norbornene, e.g., 5-vinyl-2-norbornene (VNB) and
5-allyl-2-norbornene; alicyclic polyenes, such as 2,5-norbornadiene,
dicyclopentadiene (DCPD), and tetracyclo[4,4,0,12-5,17'10] deca-3,8-diene; and
oc,co-dienes, such as 1,7-octadiene and 1,9-decadiene.
[0026]
Among them, 5-vinyl-2-norbornene (VNB), 5-alkenyl-2-norbornene,
dicyclopentadiene, 2,5-norbornadiene, 1,7-octadiene and 1,9-decadiene are
preferable, and 5-vinyl-2-norbornene (VNB) is particularly preferable.
[0027]
In this regard, the copolymer used in the present invention includes at
least one type of structural units derived from the component [C-2] and may
include at least two types of structural units derived from the component [C-2].
[0028]

In the copolymer used in the present invention, the structural units
derived from the α-olefin [B] having 3 to 20 carbon atoms constitute 10 to 50
mole%, and preferably 25 to 45 mole% in 100 mole% of the total structural
units. It is favorable that the structural units (mole%) derived from the
component [B] is within the above-described range, from the viewpoint of a
flexibility and mechanical characteristics at low temperatures of the crosslinked
foam produced from the rubber composition including the copolymer. The
above-described molar ratio can be determined on the basis of 13C-NMR.
[0029]

In the copolymer used in the present invention, the sum of the mole%
of the structural units derived from the non-conjugated polyene [C-1] and the
non-conjugated polyene [C-2] is 1.0 to 6.0 mole%. Preferably, the
above-described sum of mole% is 1.0 to 5.0 mole%. It is preferable that the
above-described sum of mole% is within the above-described range because
the vulcanization reaction rate can be controlled relatively easily. The
above-described sum of mole% can be determined by summing the molar
amounts of ENB and VNB determined on the basis of 13C-NMR.
[0030]

In the copolymer used in the present invention, the ratio ([C-1]/[C-2]) of
the mole% of the structural units derived from the non-conjugated polyene
[C-1] to the mole% of the structural units derived from the non-conjugated
polyene [C-2] is 75/25 to 99.5/0.5, preferably 78/22 to 97/3. It is preferable
that the above-described ratio of the mole% is within the above-described
range because an excellent balance between the vulcanization reactivity and

the gas-retaining property during a foaming reaction. The ratio of the mole%
can be determined on the basis of 13C-NMR.
[0031]
Herein below, a method for determining the requirements (1) to (3) will
be specifically described with referring a copolymer produced from ethylene,
propylene, 5-ethylidene-2-norbornene (ENB), and 5-vinyl-2-norbomene (VNB)
as an example.
[0032]
In this regard, the structural (compositional) analysis of the copolymer
made of ethylene, propylene and ENB through the use of 13C-NMR was
conducted on the basis of C. J. Carman, R. A. Harrington, and C. E. Wilkes,
"Macromolecules", Vol. 10, p. 536-544 (1977); Masahiro Kakugo, Yukio Naito,
Kooji Mizunuma, and Tatsuya Miyatake,"Macromolecules", Vol. 15, p.
1150-1152 (1982); and G. Van derVelden, "Macromolecules", Vol. 16, p. 85-89
(1983). The structural analysis of the VNB-based copolymer was conducted
on the basis of Harri Lasarov, Tuula T. Pakkanen, "Macromol. Rapid Commun.",
Vol. 20, p. 356-360 (1999) and Harri Lasarov*, Tuula T. Pakkanen, "Macromol.
Rapid Commun.", Vol. 22, p. 434-438 (2001).
[0033]
Initially, the integral values of individual peaks based on ethylene,
propylene, ENB, and VNB were determined through the use of 13C-NMR.
[0034]
1) Ethylene; [integral value of a peak based on ethylene chain + {integral value
of a peak based on ethylene-propylene chain}/2]
2) Propylene; [integral value of a peak based on propylene chain + {integral
value of the peak based on ethylene-propylene chain}/2]

3) ENB; integral value of a peak based on ENB-position 3
4) VNB; integral value of a peak based on VNB-position 7
[0035]
Chemical formulae of structures (E-isomer, Z-isomer) derived from
ENB and chemical formulae of structures (endo (n), exo (x)) derived from VNB
in the copolymer used in the present invention are described below.


[0038]
The mole% of the structural units derived from ENB and VNB were
calculated from the resulting integral values. In this regard, conversion to %
by weight was conducted on the assumption that the molecular weight of
ethylene was 28.05, the molecular weight of propylene was 42.08, and the
molecular weights of ENB and VNB were 120.2.
[0039]

In the copolymer used in the present invention, the Mooney viscosity
measured at 100°C as [ML1+4 (100°C)] is 10 to 90. The Mooney viscosity is
preferably 10 to 80.
[0040]
It is preferable that the Mooney viscosity is within the above-described
range because the viscosity of a rubber compound serving as a foaming
medium can be set at a low level relatively easily and a formulation excellent in
kneadability can be designed.
[0041]
In this regard, the above-described Mooney viscosity can be measured
by using a Mooney viscometer (Model SMV202 manufactured by SHIMADZU
CORPORATION) in conformity with JIS K 6300.
[0042]

In the copolymer used in the present invention, the apparent iodine
value (I V) of the structural units derived from the non-conjugated polyene [C-2]
is 0.1 to 3.0 g/100 g. The apparent iodine value of the component [C-2] is
preferably 0.4 to 3.0 g/100 g, and more preferably 0.5 to 3.0 g/100 g.

[0043]
The copolymer having activation energy of fluidization satisfying below
described requirement (6) can be obtained by adjusting the iodine value. It is
preferable that the apparent iodine value of the non-conjugated polyene [C-2]
is within the above-described range because excellent foaming ability and
excellent kneading stability are exhibited.
[0044]
In this regard, the apparent iodine value of the above-described
component [C-2] can be determined on the basis of 1H-NMR and 13C-NMR.
[0045]
A method for determining the apparent iodine value based on
5-vinyl-2-norbornene (VNB) (molecular weight: 120.2) will be described below
with referring a copolymer obtained from ethylene, propylene,
5-ethylidene-2-norbornene (ENB) and VNB, that is the copolymer used in the
present invention, as an example.
[0046]
Initially, the % by weight of each structural unit included in the
copolymer rubber was determined on the basis of the 13C-NMR as defined
above. Subsequently, the integral value of the peak based on ENB and the
integral value of the peak based on a vinyl group of VNB were determined by
1H-NMR spectrometer, as described below.
[0047]
1) [Integral value of the peak based on ENB]: (a), {(total of integral values
of a plurality of peaks in the vicinity of 4.7 to 5.3 ppm) - 2x (c)}
Since a plurality of peaks in the vicinity of 4.7 to 5.3 ppm includes both
peak (a) and peak (b), (a) is calculated from the above expression.

[0048]
2) [Integral value of the peak based on vinyl group of VNB]: (c), total of
integral values of peaks in the vicinity of 5.5 to 6.0 ppm
In this regard, the (a), (b) and (c) in the expressions 1) and 2) indicate
(a), (b) and (c) in the following formulae (X) and (Y), respectively.
[0049]
[Formula 5]

[0050]
The apparent iodine value based on VNB (molecular weight 120.2) is
calculated by the following equation using the obtained integral value ratio.
The molecular weight of iodine is 253.81.
[0051]
The apparent iodine value based on VNB = [the integral value of a
peak based on the vinyl group of VNB]/[the integral value of a peak based on
ENB] x [% by weight of ENB found from 13C-NMR spectrometer] x
253.81/120.2
[0052]

The copolymer used in the present invention satisfies the following
expression (i), and preferably satisfies the following expression (i1):
[0053]
50 > activation energy (Ea) of fluidization [kJ/mol] >35 ••• (i)
50 > activation energy (Ea) of fluidization [kJ/mol] >37 ••• (i')
[0054]
It is known that generally, the viscosity of a polymer melt decreases
with temperature increase like the viscosity of a Theologically simple liquid, and
at high temperature (Tg; glass transition temperature + 100°C), the
temperature dependence of the viscosity follows an Arrhenius type equation
represented by the following equation (A):
[0055]
viscosity (η0) = Aexp (Ea/RT) ... (A)
R; gas constant, A; frequency factor, Ea; activation energy of
fluidization, T; absolute temperature
[0056]
The above-described activation energy of fluidization is independent of
the molecular weight and the molecular weight distribution and is influenced by
only the molecular structure. Therefore, the activation energy of fluidization is
assumed to be a useful indicator, which represents structural information of a
polymer.
[0057]
Regarding an olefin-based polymer produced by using a Ziegler
catalyst, it is difficult to control the molecular structure accurately, so that the
activation energy of fluidization including various types of structural information

has been calculated. In recent years, the metallocene catalyst has been
discovered and, production technology has progressed and, thereby, the
molecular weight distribution, and even an extent of branching of short chain,
the composition distribution and an extent of branching of long chain can be
controlled. Consequently, up to now, it has been made clear that the
activation energy of fluidization of a high density polyethylene (HDPE) is about
27 kJ/mol and the activation energy of fluidization of low-density polyethylene
(LDPE) is about 56 kJ/mol. Incidentally, it is believed that a difference in
activation energy of fluidization results from long chain branching, and analysis
of long chain branching has been evaluated by NMR and light scattering.
However, accurate results are not always obtained. Consequently, intensive
research has been still conducted taking note of the rheological characteristics
(Reference 1: Masayuki Yamaguchi, "Seikei-Kakou", Vol. 20, No. 7, p.400-404
(2008); and Reference 2: F. J. Stadler, C. Gabriel, and H. Munstedt,
"Macromolecular Chemistry and Physics", Vol. 208, p. 2449-2454 (2007)).
[0058]
On the other hand, it has been reported that in EPDM produced by
using the metallocene catalyst, copolymerized diene components are uniformly
distributed in the molecular structure of the EPDM (Reference 3: B. A.
Harrington and M. G. Williams, "American Chemical Society Rubber Division
Technical Meeting", October 2003, p. 14-17).
[0059]
That is, it becomes possible to control the molecular structure of the
EPDM accurately by using the metallocene catalyst and, at the same time, it
becomes possible to level the crosslinking activity. As a result, the
relationship between the activation energy of fluidization and the properties of

the rubber composition, and the cross-linked foam can be grasped, so that it is
possible to clarify a structural region that exhibits an excellent performance in
high foaming regions.
[0060]
In general, in order to prepare a crosslinked foam by crosslinking
foaming of a composition including an ethylene-propylene'diene copolymer
rubber (EPDM), it is important to control the vulcanization reaction and the
foaming reaction, as well as the properties of the composition.
[0061]
For example, if the viscosity of the composition is too low, the foaming
gas-retaining property becomes poor and, thereby, the specific gravity cannot
be reduced so as to cause deterioration in appearance. Conversely, if the
viscosity of the composition is too high, foaming is not effected. Furthermore,
network formation due to the crosslinking reaction of the EPDM is mentioned
as one of the factors having an influence on the viscosity of the composition,
and it is also important to control the crosslinking reaction.
[0062]
In the past, in order to improve the foaming gas-retaining property
under the condition, in which the viscosity of the composition is reduced, it has
been investigated to improve the gas-retaining property by conducting a
molecular design in such a way as to expand the molecular weight distribution
of the EPDM and introducing a high molecular weight component. In this
regard, it is well known that the gas-retaining property is improved by
introducing a long chain branch into a polymer. However, regarding the
conventional EPDM through the use of the Ziegler catalyst, the introduction in
itself of the long chain branch is difficult. Moreover, as described above, the

diene component is not distributed uniformly in the polymer, so that the
crosslinking reaction is unevenly distributed and, as a result, it is difficult to
obtain an adequately highly foamed product.
[0063]
Therefore, the copolymer used in the present invention is preferably
synthesized using a metallocene catalyst to uniformly introduce the diene
component into the polymer to control the crosslinking reaction. In addition,
the component [C-2], such as 5-vinyl-2-norbornene (VNB), is copolymerized as
one diene component to introduce more long chain branching. Its structural
properties are specified by the activation energy of fluidization. With a
crosslinked and foamed product obtained by crosslinking and foaming a
composition including the above copolymer in which the activation energy of
fluidization satisfies the above expression (i), it becomes possible to easily and
stably perform the preparation of a highly foamed product, which has so far
been difficult to achieve. In addition, the crosslinked foam obtained with the
composition including the above copolymer exhibits significantly excellent
surface smoothness.
[0064]
The activation energy (Ea) of fluidization of the copolymer used in the
present invention is a numerical value calculated by an Arrhenius type
equation from a shift factor (aT) in preparing a master curve that indicates the
dependence of the melt complex viscosity (unit: Pa-sec) at 190°C on the
frequency (unit: Hz), on the basis of the temperature-time superposition
principle. The Ea is determined by the following method:
[0065]
That is, each melt complex viscosity-frequency curve (unit of the melt

complex viscosity; Pa/sec, unit of frequency; Hz) of the copolymer at each
temperature (T, unit: °C) of 170°C and 210°C is superposed on the melt
complex viscosity-frequency curve of the copolymer at 190°C on the basis of
the temperature-time superposition principle so as to determine a shift factor
(aT) at each temperature (T). From each temperature (T) and the shift factor
(aT) at each temperature (T), a linear approximate equation (the following
equation (I)) of [In(aT)] and [1/(T+273.16)] is calculated by the method of least
squares. Next, the Ea is determined from a slope m in the linear approximate
equation and the following equation (II):
[0066]
In(aT) = m(1 /(T + 273.16)) + n (I)
Ea = [0.008314 x m] (II)
aT: shift factor, Ea: activation energy of fluidization (unit: kJ/mol)
T: temperature (unit: °C), n: intercept.
[0067]
The above calculation can be conducted by using a commercially
available calculation software and RSI Orchestrator VER. 6.6.3: released from
TA Instruments Japan Inc. is exemplified as the calculation software.
[0068]
In this regard, the shift factor (aT) is the amount of movement in the
case where the logarithmic curve of the melt complex viscosity-frequency at
each temperature (T) is moved in a log(Y) = -log(X) axis direction (where the Y
axis indicates the melt complex viscosity and the X axis indicates the
frequency) and is superposed on the melt complex viscosity-frequency curve
at 190°C. In the superposing, the logarithmic curve of the melt complex
viscosity-frequency at each temperature (T) is moved in such a way that the

frequency is multiplied by a factor of aT and the melt complex viscosity is
multiplied by a factor of 1/aT. In this connection, in determination of the
equation (I) obtained from the shift factors (aT) and the temperature (T) by the
method of least squares at three temperatures of 170°C, 190°C and 210°C, the
correlation coefficient is usually 0.99 or more.
[0069]
The measurement of melt complex viscosity-frequency curve was
conducted by using a viscoelasticity measuring apparatus (e.g., viscoelasticity
measuring apparatus (Type: RDS-2) manufactured by Rheometrics, Inc.).
Concretely, as for a test piece, a piece having a disk shape of 25 mm-diameter
x 2 mm-thick prepared from a sheet of 2 mm-thick prepared by pressing a
copolymer at 190°C was used and the measurement was carried out with the
following conditions. In this regard, RSI Orchestrator VER. 6.6.3: released
from TA Instruments Japan Inc. was used as a data-processing software. In
addition, an appropriate amount (for example, about 1,000 ppm) of antioxidant
is preferably added previously in the test piece.
[0070]
Geometry: parallel plate
Measurement temperature: 170°C, 190°C, and 210°C
Frequency: 0.5 to 79.577 Hz
Rate of strain: 1.0%.
The frequency dependence of the viscosity was measured under the
above-described condition, and the activation energy of fluidization was
calculated by leading the above-described Arrhenius plots.
[0071]
As described above, the copolymer used in the present invention is a

copolymer synthesized through the use of the metallocene catalyst. As for
the metallocene catalyst, a catalyst represented by the following formula (I), (II),
or (III) is preferable.
[0072]
The compounds represented by the formula (I) will be described.
[0073]
[Formula 6]

[0074]
In the formula (I), each R represents independently a group selected
from hydrocarbyl, halohydrocarbyl, silyl, germyl, and combinations thereof or a
hydrogen atom, and the number of atoms included in the group is 20 or less
excluding hydrogen.
[0075]
M represents titanium, zirconium, or hafnium.
[0076]
Y represents -O-, -S-, -NR*-, or -PR*-.
[0077]
R* represents a hydrogen atom, a hydrocarbyl group, a hydrocarbyloxy
group, a silyl group, a halogenated alkyl group, or a halogenated aryl group,
and in the case where R* is not hydrogen, R* includes 20 or less of atoms
excluding hydrogen.

[0078]
Z represents a divalent group including boron or a group 14 element
and, in addition, containing nitrogen, phosphorus, sulfur, or oxygen, and the
number of atoms included in the divalent group is 60 or less excluding
hydrogen.
[0079]
X, independently in the case where a plurality of Xs is present,
represents an anionic ligand having the number of atoms of 60 or less (where a
cyclic ligand, in which π electrons are delocalized, is excluded.).
[0080]
X', independently in the case where a plurality of X's is present,
represents a neutral linked compound having the number of atoms of 20 or
less.
[0081]
The letter p represents 0, 1, or 2.
[0082]
The letter q represents 0 or 1.
[0083]
With the proviso that, in the case where p is 2 and q is 0, M is in an
oxidized state of +4, X is an anionic ligand selected from the group consisting
of halides, hydrocarbyl, hydrocarbyloxy, di(hydrocarbyl)amide,
di(hydrocarbyl)phosphide, hydrocarbyl sulfide, silyl group, halo-substituted
derivatives thereof, di(hydrocarbyl)amino-substituted derivatives thereof,
hydrocarbyloxy-substituted derivatives thereof, and
di(hydrocarbyl)phosphine-substituted derivatives thereof, and the number of
atoms of X is 20 or less excluding hydrogen. Furthermore, in the case where

p is 1 and q is 0, M is in an oxidized state of +3 and X is an anionic stabilizing
ligand selected from the group consisting of allyl,
2-(N,N'-dimethylaminomethyl)phenyl, and 2-(N,N'-dimethyl)aminobenzyl or M
is in an oxidized state of +4, and X is a divalent conjugated diene derivative
and forms metallacyclopentene with M. Alternatively, in the case where p is 0
and q is 1, M is in an oxidized state of +2, and X' is a neutral conjugated or
non-conjugated diene, which may be substituted with at least one hydrocarbyl
group, which has the number of carbon atoms of 40 or less, and which forms a
71 complex with M.
[0084]
The compounds represented by the formula (II) will be described.
[0085]
[Formula 7]

[0086]
In the formula (II), R1 and R2 represent independently a hydrogen atom
or an alkyl group having 1 to 6 carbon atoms, and at least one of R1 and R2 is
not a hydrogen atom.
R3 to R6 represent independently a hydrogen atom or an alkyl group having 1
to 6 carbon atoms.
In addition, R1 to R6 may be bonded to each other so as to form a ring.
M represents titanium.

Y represents -0-, -S-, -NR*-, or -PR*-.
Z* represents SiR*2, CR*2, SiR*2SiR*2, CR*2CR*2, CR*=CR*, CR*2SiR*2, or
GeR*2.
[0087]
Each R* represents independently a hydrogen atom, a hydrocarbyl
group, a hydrocarbyloxy group, a silyl group, a halogenated alkyl group, or a
halogenated aryl group, and in the case where R* is not hydrogen, R* includes
20 or less of atoms excluding hydrogen. Two R*s (in the case where R* is not
hydrogen) bonded to Z* may form a ring, or one R* bonded to Z* and one R*
bonded to Y may form a ring.
The letter p represents 0, 1, or 2.
The letter q represents 0 or 1.
With the proviso that, in the case where p takes on 2, q is 0, M is in an oxidized
state of +4, each X represents independently a methyl group or a benzyl group.
Alternatively, in the case where p takes on 1, q is 0, M is in an oxidized state of
+3, and X is a 2-(N,N'-dimethyl)aminobenzyl group or q is 0, M is in an oxidized
state of +4, and X is 1,3-butadienyl. Alternatively, in the case where p takes
on 0, q is 1, M is in an oxidized state of+2, and X' is 1,4-diphenyl-1,3-butadiene,
2,4-hexadiene, or 1,3-pentadiene.
[0088]
The compounds represented by the formula (III) will be described.
[0089]

[Formula 8]

[0090]
In the formula (III), R' represents a hydrogen atom, a hydrocarbyl
group, a di(hydrocarbylamino) group, or a hydrocarbyleneamino group, and in
the case where R' described above has carbon atoms, the number of carbon
atoms is 20 or less.
In the formula (III), R" represents a hydrocarbyl group having 1 to 20 carbon
atoms or a hydrogen atom.
In the formula (III), M represents titanium.
In the formula (III), Y represents -0-, -S-, -NR*-, -PR*-, -NR*2, or -PR*2.
In the formula (III), Z* represents -SiRV, -CRV, -SiR*2SiR*2-, -CR*2CR*2-,
-CR*=CR*-, -CR*2SiR*2-, or -GeR*2-
R*, independently in the case where a plurality of R*s described above is
present, represents a hydrogen atom or a group containing at least one group
selected from the group consisting of hydrocarbyl, hydrocarbyloxy, silyl,
halogenated alkyl, and halogenated aryl, R* described above includes an atom
of the atomic number of 2 to 20, and two R*s (in the case where R* is not a
hydrogen atom) optionally included in Z* may form a ring, or one R* in Z* and
one R* in Y may form a ring.
[0091]
In the formula (III), X represents a monovalent anionic ligand having

the number of atoms of 60 or less excluding cyclic ligands, in which n electrons
are delocalized. X' represents a neutral linked group having the number of
atoms of 20 or less. X" represents a divalent anionic ligand having the
number of atoms of 60 or less. The letter p represents 0, 1, or 2. The letter q
represents 0 or 1. The letter r represents 0 or 1.
[0092]
In the case where p takes on 2, q and r are 0, M is in an oxidized state
of +4 (where the case, in which Y is -NR*2 or -PR*2, is excluded) or M is in an
oxidized state of +3 (where Y is -NR*2 or -PR*2), and X is an anionic ligand
selected from the group consisting of a halide group, a hydrocarbyl group, a
hydrocarbyloxy group, a di(hydracarbyl)amide group, a
di(hydrocarbyl)phosphide group, a hydrocarbyl sulfide group, a silyl group,
halogen-substituted groups of these groups, di(hydrocarbyl)amino-substituted
groups of these groups, hydrocarbyloxy-substituted groups of these groups,
and di(hydrocarbyl)phosphino-substituted groups of these groups while the
above-described groups include atoms of the atomic number of 2 to 30.
[0093]
In the case where r takes on 1, p and q are 0, M is in an oxidized state
of +4, X" is a dianionic ligand selected from the group consisting of a
hydrocarbazyl group, an oxyhydrocarbyl group, and a hydrocarbylenedioxy
group, and X" described above includes atoms of the atomic number of 2 to 30.
In the case where p takes on 1, q and r are 0, M is in an oxidized state of +3,
and X is an anionic stabilizing ligand selected from the group consisting of allyl,
2-(N,N-dimethylamino)phenyl, 2-(N,N-dimethylaminomethyl)phenyl, and
2-(N,N-dimethylamino)benzyl. In the case where p and rtake on 0, q is 1, M
is in an oxidized state of +2, X' is a neutral conjugated diene or a neutral

diconjugated diene substituted with at least one hydrocarbyl group optionally,
and X" described above has the number of carbon atoms of 40 or less and
forms a bond with M through n-n interaction.
[0094]
As for more preferable embodiments, in the case where p takes on 2
and q and rtake on 0 in the formula (III), M is in an oxidized state of +4, and
each of X is independently methyl, benzyl, or halide. In the case where p and
q take on 0, r is 1, M is in an oxidized state of +4, and X" is a 1,4-butadienyl
group, which forms a metallacyclopentene ring with M. In the case where p
takes on 1, q and r are 0, M is in an oxidized state of +3, and X is
2-(N,N-dimethylamino)benzyl. In the case where p and r take on 0, q is 1, M
is in an oxidized state of +2, and X' is 1,4-diphenyl-1,3-butadiene or
1,3-pentadiene.
[0095]
The compounds represented by the following formula (III') among the
formula (III) are particularly preferable.
[0096]
[Formula 9]

[0097]
In the above-described formula (III'), R' represents a hydrogen atom or
a hydrocarbyl group having 1 to 20 carbon atoms, R" represents a hydrocarbyl

group having 1 to 20 carbon atoms or a hydrogen atom, M represents titanium,
Y represents -NR*-, Z* represents -SiR*2-, each R* described above represents
independently a hydrogen atom or a hydrocarbyl group having 1 to 20 carbon
atoms, one of p and q is 0 and the other is 1. In the case where p takes on 0
and q takes on 1, M is in an oxidized state of +2 and X' is
1,4-diphenyl-1,3-butadiene or 1,3-pentadiene. In the case where p takes on 1
and q takes on 0, M is in an oxidized state of +3, and X is
2-(N,N-dimethylamino)benzyl.
[0098]
Examples of hydrocarbyl groups having 1 to 20 carbon atoms include
linear alkyl groups, such as methyl group, ethyl group, and butyl group, and
branched alkyl groups, such as t-butyl group and neopentyl group. Examples
of hydrocarbyloxy groups include linear alkyloxy groups, such as methyloxy
group, ethyloxy group, and butyloxy group, and branched alkyloxy groups,
such as t-butyloxy group and neopentyloxy group. Examples of halogenated
alkyl groups include groups produced by chlorinating, brominating, or
fluorinating the above-described linear or branched alkyl groups.
Furthermore, examples of halogenated aryl groups include chlorinated phenyl
groups and chlorinated naphthyl groups.
In the above-described formula (III'), it is preferable that R" is a hydrogen atom
or methyl and the case of methyl is particularly preferable.
[0099]
Particularly preferable catalysts include:
(t-butylamide)dimethyl(η5-2-methyl-s-indacen-1-yl)silane-titanium(ll)
2,4-hexadiene (formula (IV)),
(t-butylamide)dimethyl(ri5-2-methyl-s-indacen-1-yl)silane-titanium(IV)

dimethyl (formula (V)),
(t-butylamide)dimethyl(η5-2,3-dimethylindenyl)silane-titanium(ll)
1,4-diphenyl-1,3-butadiene (formula (VI)),
(t-butylamide)dimethyl (η5-2,3-dimethyl-s-indacen-1-yl)
silane-titanium(IV) dimethyl (formula (VII)), and
(t-butylamide)dimethyl(η5-2-methyl-s-indacen-1-yl)silane-titanium(ll)
1,3-pentadiene (formula (VIII)).
Among them, (t-butylamide)dimethyl(r)5-2-methyl-s-indacen-1-yl)
silane-titanium(ll) 1,3-pentadiene (formula (VIII)) is particularly preferable.
[0100]



[0102]
Particularly, if the catalyst having a structure represented by the
above-described formula (VIM) is used, the polymerization reaction for
obtaining the copolymer used in the present invention is excellent in
copolymerizability of non-conjugated polyenes (component [C-1] and

component [C-2]). For example, the double bond at a VNB terminal is taken
in efficiently and long chain branches can be introduced at a high proportion.
Furthermore, the molecular weight distribution and the composition distribution
of the resulting copolymer are narrow and the copolymer having a very uniform
molecular structure can be prepared. Therefore, formation of gel-like blobs,
which is feared accompanying with generation of long chain branches, on a
surface of a rubber molding product is suppressed significantly. Consequently,
excellent appearance of the surface thereof is exhibited, and a shape-retaining
property is excellent, so that good production stability is exhibited.
[0103]
These catalysts can be prepared by using a known synthesis method,
such as a method disclosed in WO 98/49212 .
[0104]

When the copolymer used in the present invention is synthesized, a
metallocene catalyst, preferably a catalyst having a structure illustrated above,
is used. More particular examples include a continuous method or a batch
method using the above catalyst as a main catalyst, a boron compound and/or
an organo-aluminum compound, such as a trialkylated compound, as a
cocatalyst, an aliphatic hydrocarbon, such as hexane, as a solvent, and a
reactor with an agitator.
[0105]
Examples of boron compounds include:
trimethylammonium tetrakis(pentafluorophenyl)borate,
di(hydrogenated-tallowalkyl)methylammonium
tetrakis(pentafluorophenyl)borate,

triethylammonium tetrakis(pentafluorophenyl)borate,
tripropylammonium tetrakis(pentafluorophenyl)borate,
tri(n-butyl)ammonium tetrakis(pentafluorophenyl)borate,
tri(sec-butyl)ammonium tetrakis(pentafluorophenyl)borate,
N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate,
N,N-dimethylanilinium n-butyltris(pentafluorophenyl)borate,
N.N-dimethylanilinium benzyltris(pentafluorophenyl)borate,
N,N-dimethylanilinium tetrakis(4-(t-butyldimethylsilyl)-2,3,5,6-
tetrafluorophenyl)borate,
N,N-dimethylanilinium tetrakis(4-(triisopropylsilyl)2,3,5,6-
tetrafluorophenyl)borate,
N,N-dimethylanilinium pentafluorophenoxytris(pentafluoro-
phenyl)borate,
N,N-diethylanilinium tetrakis(pentafluorophenyl)borate,
N,N-dimethyl-2,4,6-trimethylanilinium tetrakis(pentafluoro-
phenyl)borate,
trimethylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate,
triethylammonium tetrakis(2,3,4,6-tetrafluoropheny!)borate,
tripropylammonium tetrakis(2,3,4,6-tetrafluorophenyl)borate,
N,N-dimethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate,
N,N-diethylanilinium tetrakis(2,3,4,6-tetrafluorophenyl)borate, and
N,N-dimethyl-2,4,6-trimethylanilinium tetrakis(2,3,4,6-tetrafluoro-
phenyl)borate;
dialkylammonium salts, e.g., di-(i-propyl)ammonium tetrakis-
(pentafluorophenyl)borate, tri(n-butyl)ammonium tetrakis(2,3,4,6-tetrafluoro-
phenyl)borate, dimethyl (t-butyl) ammonium tetrakis(2,3,4,6-tetrafluoro-

phenyl)borate, and dicyclohexylammonium tetrakis(pentafluorophenyl)borate;
trisubstituted phosphonium salts, e.g., triphenylphosphonium tetrakis-
(pentafluorophenyl)borate, tri(o-tolyl)phosphonium tetrakis(pentafluoro-
phenyl)borate, and tri(2,6-dimethylphenyl)phosphonium tetrakis(pentafluoro-
phenyl)borate;
disubstituted oxonium salts, e.g., diphenyloxonium tetrakis-
(pentafluorophenyl)borate, di-(o-tolyl)oxonium tetrakis(pentafluoro-
phenyl)borate, and di(2,6-dimethylphenyl)oxonium tetrakis(pentafluoro-
phenyl)borate; and
disubstituted sulfonium salts, e.g., diphenylsulfonium tetrakis-
(pentafluorophenyl)borate, di(o-tolyl)sulfonium tetrakis(pentafluoro-
phenyl)borate, and bis(2,6-dimethylphenyl)sulfonium tetrakis(pentafluoro-
phenyl)borate.
[0106]
As for the organo-aluminum compound, tri-isobutyl aluminum
(hereinafter also referred to as "TIBA") is mentioned. The reaction
temperature can be raised to 100°C because the catalyst is not deactivated
even at high temperatures. The polymerization pressure is usually within the
range of from more than 0 MPa, to 8 MPa (gauge pressure), and preferably
from more than 0 MPa to 5 MPa (gauge pressure). In addition, the reaction
time (average retention time when copolymerization is carried out by the
continuous method) is usually 0.5 minutes to 5 hours, preferably 10 minutes to
3 hours, though different depending on conditions, such as catalyst
concentration and polymerization temperature. Furthermore, a molecular
weight modifier, e.g., hydrogen, can be used in copolymerization.
[0107]

The molar ratio (of charge) ([A]/[B]) of ethylene [A] to a-olefin [B] is
25/75 to 80/20, and preferably 30/70 to 70/30.
[0108]
The molar ratio (of charge) ([C-1]/[C-2J) of the non-conjugated polyene
[C-1] to the non-conjugated polyene [C-2] is 60/40 to 99.5/0.5, and preferably
65/35 to 99/1.
[0109]
The molar ratio (of charge) ([A]/[C-1]) of ethylene [A] to the
non-conjugated polyene [C-1] is 70/30 to 99/1, and preferably 80/20 to 98/2.
[0110]
The molar ratio (of charge) ([A]/[C-2]) of ethylene [A] to the
non-conjugated polyene [C-2] is 70/30 to 99.9/0.1, and preferably 80/20 to
99.5/0.5.
[0111]
It is preferable that the polymerization is conducted by using the
above-described catalyst because the non-conjugated polyenes having a
double bond and the like are copolymerized in high conversion and an
appropriate amount of long chain branches can be introduced in the resulting
copolymer.
[0112]
The thus obtained copolymer used in the present invention includes 10
to 50 mole%, and preferably 25 to 45 mole% of the structural units derived
from the a-olefin [B] having 3 to 20 carbon atoms in 100 mole% of the total
structural units. Moreover, the sum of the mole% of the structural units
derived from the non-conjugated polyene [C-1], in which among carbon-carbon
double bonds, only one carbon-carbon double bond polymerizable with the

metallocene catalyst is present in one molecule, and the mole% of the
structural units derived from the non-conjugated polyene [C-2], in which among
the carbon-carbon double bonds, two carbon-carbon double bonds
polymerizable with the metallocene catalyst are present in one molecule, is 1.0
to 6.0 mole%, and preferably 1.0 to 5.0 mole%. The ratio ([C-1]/[C-2]) of the
mole% of the structural units derived from the non-conjugated polyene [C-1], in
which among carbon-carbon double bonds, only one carbon-carbon double
bond polymerizable with the metallocene catalyst is present in one molecule, to
the mole% of the structural units derived from the non-conjugated polyene
[C-2], in which among the carbon-carbon double bonds, two carbon-carbon
double bonds polymerizable with the metallocene catalyst are present in one
molecule, is 75/25 to 99.5/0.5, and preferably 78/22 to 97/3.
[0113]
It is preferable that the polymerization is conducted by using the
above-described catalyst because the non-conjugated polyenes having a
double bond and the like are copolymerized in high conversion and an
appropriate amount of long chain branches can be introduced in the resulting
copolymer.
[0114]

A rubber composition used in the present invention should include the
above copolymer [I] and can preferably include, but not particularly limited, for
example, a reinforcing agent such as carbon black, a softening agent such as
an oil, a vulcanizing agent and a vulcanization aid, and a foaming agent and a
foaming aid. The content of the above copolymer (I) in the entire rubber
composition is preferably 20% by weight or more.

[0115]

Carbon black is used in the proportion of 30 to 300 parts by weight,
preferably 50 to 200 parts by weight, further preferably 61 to 200 parts by
weight, and most preferably 70 to 200 parts by weight, based on 100 parts by
weight of the ethylene-ct-olefin-non-conjugated polyene copolymer rubber [I] in
order to obtain a rubber composition that can provide a vulcanized rubber
molded product by extrusion molding with sufficient mechanical strength. In
addition, the carbon black is used in the proportion of 30 to 300 parts by weight,
preferably 50 to 200 parts by weight, further preferably 61 to 200 parts by
weight, and most preferably 80 to 200 parts by weight, based on 100 parts by
weight of the ethylene-α-olefin-non-conjugated polyene copolymer rubber [I] in
order to obtain a rubber composition that can provide a vulcanized rubber
compact having sufficient mechanical strength.
[0116]
As the carbon black, SRF, GPF, FEF, MAF, HAF, ISAF, SAF, FT, MT,
and the like can be used. In addition, as a commercial product, FEF carbon
black (Asahi #60G manufactured by ASAHl CARBON CO., LTD) is preferred.
The carbon black preferably has a nitrogen adsorption specific surface area of
10 to 100 m2/g in order to obtain a rubber composition that can provide a
vulcanized rubber molded product having good mechanical strength and a
good product skin.
[0117]

Conventionally known additives, such as rubber-reinforcing agents
other than carbon black (B), inorganic fillers, softening agents, anti-aging

agents, processing aids, foaming agents, foaming aids, vulcanization
accelerators, organic peroxides, vulcanization aids, coloring agents,
dispersants, and flame retardants, can be blended into the rubber composition
used in the present invention according to the intended application of the
vulcanizate, and the like in a range that does not impair the object of the
present invention.
[0118]
The above rubber-reinforcing agent is effective in increasing the
mechanical properties, such as tensile strength, tear strength, and wear
resistance, of a crosslinked (vulcanized) rubber. Specific examples of such
rubber-reinforcing agents include fine powder silicic acid, and silica. These
may be previously subjected to silane coupling treatment.
[0119]
Specific examples of the silica include aerosol silica and precipitated
silica. These silicas may be surface-treated with a reactive silane, such as
mercaptosilanes, aminosilanes, hexamethyldisilazane, chlorosilanes and
alkoxysilanes, a low molecular weight siloxane, or the like.
[0120]
A type and a blending amount of these rubber-reinforcing agents can
be appropriately selected according to the application. The blending amount
of the rubber-reinforcing agent (excluding carbon black) is usually 150 parts by
weight at the maximum, preferably 100 parts by weight at the maximum, based
on 100 parts by weight of the ethylene α-olefin-non-conjugated polyene
copolymer rubber [I].
[0121]

Specific examples of the above inorganic fillers include precipitated
calcium carbonate, heavy calcium carbonate, talc, and clay.
[0122]
A type and a blending amount of these inorganic fillers can be
appropriately selected according to the application. The blending amount of
the inorganic filler is usually 300 parts by weight at the maximum, preferably
200 parts by weight at the maximum, based on 100 parts by weight of the
ethylene-α-olefin-non-conjugated polyene copolymer rubber [I].
[0123]

As the above softening agent, softening agents conventionally used in
rubbers can be used. Specific examples of the softening agents include
petroleum-based softening agents, such as process oils, lubricating oils,
paraffin oils, liquid paraffin, petroleum asphalts and Vaseline; coal tar-based
softening agents, such as coal tars and coal tar pitches; fatty oil-based
softening agents, such as castor oil, linseed oil, rapeseed oil, soybean oil and
coconut oil; tall oil; Rubber Substitutes (factice); waxes, such as bees wax,
carnauba wax and lanolin; fatty acids and fatty acid salts, such as ricinoleic
acid, palmitic acid, stearic acid, barium stearate, calcium stearate and zinc
laurate; naphthenic acid; pine oil, rosin, or derivatives thereof; synthetic
polymeric substances, such as terpene resins, petroleum resins, atactic
polypropylene and coumarone-indene resins; ester-based softening agents,
such as dioctyl phthalate, dioctyl adipate and dioctyl sebacate; microcrystalline
waxes, liquid polybutadiene, modified liquid polybutadiene, liquid Thiokol, and
hydrocarbon-based synthetic lubricating oils. Among them, petroleum-based
softening agents, particularly process oils, are preferably used. A blending

amount of these softening agents is appropriately selected according to the
application of the vulcanizate.
[0124]

Examples of the above anti-aging agents include amine-based,
hindered phenol-based, or sulfur-based anti-aging agents. These anti-aging
agents are used in a range that does not impair the object of the present
invention, as described above. Examples of the amine-based anti-aging
agents include diphenylamines and phenylenediamines. As the sulfur-based
anti-aging agents, sulfur-based anti-aging agents conventionally used in
rubbers are used.
[0125]

As the above processing aid, processing aids used in usual rubber
processing can be used. Specific examples of the processing aids include
higher fatty acids, such as linoleic acid, ricinoleic acid, stearic acid, palmitic
acid, and lauric acid; salts of higher fatty acids, such as barium stearate, zinc
stearate, and calcium stearate; and esters of the above higher fatty acids.
Such a processing aid is usually used in the proportion of 10 parts by weight or
less, preferably 5 parts by weight or less, based on 100 parts by weight of the
ethylene α-olefin-non-conjugated polyene copolymer rubber [I]. It is desired
to appropriately determine the optimum amount according to the required
physical property values.
[0126]

Specific examples of the foaming agents include inorganic foaming

agents, such as sodium bicarbonate (baking soda), sodium carbonate,
ammonium bicarbonate, ammonium carbonate, and ammonium nitrite; nitroso
compounds, such as N,N'-dimethyl-N,N'-dinitrosoterephthalamide and
N.N'-dinitrosopentamethylenetetramine (DPT); azo compounds, such as
azodicarbonamide (ADCA), azobisisobutyronitrile (AZBN),
azobiscyclohexylnitrile, azodiaminobenzene, and barium azodicarboxylate;
sulfonyl hydrazide compounds, such as benzenesulfonyl hydrazide (BSH),
toluenesulfonyl hydrazide (TSH), p,p'-oxybis(benzenesulfonyl hydrazide)
(OBSH), and diphenyl sulfone-3,3'-disulfonyl hydrazide; and azide compounds,
such as calcium azide, 4,4'-diphenyldisulfonyl azide, and p-toluenesulfonyl
azide.
[0127]
These foaming agents are usually used in the proportion of 0.5 to 30
parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by
weight of the ethylene α-olefin-non-conjugated polyene copolymer rubber [I].
[0128]

In addition, a foaming aid may be used in combination with the foaming
agent, as required. The foaming aid has the functions of decreasing the
decomposition temperature of the foaming agent, accelerating decomposition,
uniform void formation, and the like. Examples of the foaming aids include
organic acids, such as salicylic acid, phthalic acid, stearic acid, and oxalic acid,
urea, or derivatives thereof. These foaming aids are usually used in the
proportion of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight,
based on 100 parts by weight of the ethylene α-olefin-non-conjugated polyene
copolymer rubber [I]. It is desired to appropriately determine the optimum

amount according to the required physical property values.
[0129]

In addition, known other rubbers can be blended into the crosslinkable
rubber composition used in the present invention in a range that does not
impair the object of the present invention for use. Examples of such other
rubbers can include natural rubbers (NR), isoprene-based rubbers, such as
isoprene rubbers (IR), and conjugated diene-based rubbers, such as butadiene
rubbers (BR), styrene-butadiene rubbers (SBR), acrylonitrile-butadiene
rubbers (NBR), and chloroprene rubbers (CR).
[0130]

Examples of the vulcanizing agents used for vulcanization include
sulfur and sulfur compounds. Specific examples of the sulfur include
powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and
insoluble sulfur. Specific examples of the sulfur compounds include sulfur
chloride, sulfur dichloride, polymeric polysulfides, and sulfur compounds that
release active sulfur for vulcanization at vulcanization temperature, for
example, morpholine disulfide, alkylphenol disulfide, tetramethylthiuram
disulfide, dipentamethylenethiuram tetrasulfide, and selenium
dimethyldithiocarbamate. Among them, sulfur is preferred. The sulfur or the
sulfur compound is usually used in the proportion of 0.1 to 10 parts by weight,
preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the above
copolymer rubber [I].
[0131]

The vulcanization aid can be appropriately selected according to the
application. A vulcanization aid can be used alone, or two or more
vulcanization aids can be mixed and used. Specific examples of the
vulcanization aids include magnesium oxide and zinc flower (zinc oxide, for
example, "META-Z102" (trade name; manufactured by Inoue Calcium
Corporation)). The amount of the vulcanization aid blended is usually 1 to 20
parts by weight based on 100 parts by weight of the copolymer. Examples of
other vulcanization aids include quinone dioxime-based aids, such as
p-quinone dioxime; acrylic aids, such as ethylene glycol dimethacrylate and
trimethylolpropane trimethacrylate; allyl-based aids, such as diallyl phthalate
and triallyl isocyanurate; additional maleimide-based aids; and divinylbenzene.
[0133]
Preparation of Rubber Composition and Vulcanized Rubber Molded
Product Thereof>
The rubber composition used in the present invention can be prepared
by kneading the ethylene-a-olefinnon-conjugated polyene copolymer rubber [I]
and additives, such as carbon black, a rubber-reinforcing agent, an inorganic
filler, and a softening agent, by an internal mixer (closed mixer) such as a
Banbury mixer, a kneader, or Intermix at a temperature of 80 to 170°C for 2 to
20 minutes. The mixture is then kneaded with mixing sulfur, additionally

mixing as required, a vulcanization accelerator, a vulcanization aid, a foaming
agent and a foaming aid, at a roll temperature of 40 to 80°C for 5 to 30 minutes
using a roll such as an open roll or a kneader, and then sheeting the kneaded
material to prepare the rubber composition.
[0134]

Acrosslinked rubber used in the present invention is characterized by
being obtained by crosslinking the above rubber composition. Examples of
methods for crosslinking the rubber composition include the following two
methods. A first method (i) includes premolding into the desired shape the
rubber composition in which the above vulcanizing agent is blended, usually by
various molding methods using, such as, an extrusion machine, a calender roll,
a press machine, an injection molding machine, a transfer molding machine,
and a heating vessel in the form of heating, such as hot air, a glass bead
fluidized bed, UHF (ultrahigh frequency electromagnetic wave) and steam, e.g.,
LCM (hot molten salt vessel), and heating simultaneously with the premolding
or after introducing the molded material into a vulcanization vessel. A second
method (ii) includes premolding the above rubber composition by the above
molding methods and irradiating the premolded rubber composition with an
electron beam.
[0135]
In the case of (i), the above vulcanizing agent is used, and the above
vulcanization accelerator and/or the above vulcanization aid can also be used
in combination as required. In addition, the temperature in heating is
generally 100 to 300°C, preferably 120 to 270°C, and further preferably 120 to
250°C, and it is desired to perform heating for 0.5 to 30 minutes, preferably 0.5

to 20 minutes, and further preferably 0.5 to 15 minutes.
[0136]
The molding and vulcanization of the above rubber composition can be
carried out by using a mold or no mold. When the mold is not used, the
rubber composition is usually continuously molded and vulcanized.
[0137]
When the rubber composition used in the present invention is
subjected to the above molding method (ii) of premolding the rubber
composition and irradiating with an electron beam, the electron beam having
an energy of 0.1 to 10 MeV can irradiate to the premolded rubber composition
so as to be the absorbed dose of 0.5 to 35 Mrad, preferably 0.5 to 20 Mrad,
and more preferably 1 to 10 Mrad.
[0138]

A crosslinked foam used in the present invention is a crosslinked and
foamed product obtained by crosslinking and foam-molding the above rubber
composition (hereinafter referred to as a "crosslinked foam (1)."). The
crosslinking and foam-molding the above rubber composition is usually
performed by using a rubber composition containing a foaming agent, and
crosslinking and foaming thereof. One example of the crosslinking and
foam-molding includes a method of filling a mold having a predetermined
shape with the rubber composition and crosslinking and foaming the rubber
composition by a hot press to obtain a track pad. The type of the track pad
includes those mentioned in JIS E 1117 but, of course, is not limited to these.
[0139]
On the other hand, the crosslinked foam of the present invention is

crosslinked foams (2) and (3) having the following particular physical
properties.
[0140]
The crosslinked foam (2) of the present invention is a crosslinked and
foamed product obtained by crosslinking and foaming a composition containing
an ethylene α-olefin-non-conjugated polyene random copolymer, wherein
(a) the specific gravity thereof is 0.75 or less, and
(b) the elastic modulus thereof is 3.0 N/mm2 or more.
[0141]
The crosslinked foam (3) of the present invention is a crosslinked and
foamed product obtained by crosslinking and foaming a composition containing
an ethylene α-olefin-non-conjugated polyene random copolymer, wherein
(a) the specific gravity thereof is 0.75 or less, and
(c) an average value of diameters of voids from a maximum diameter
void to a 10th largest diameter void among voids observed in a fixed area (2.2
cm2) of a cross section of a molded product is 80 µm or less.
[0142]
The above crosslinked foams (2) and (3) of the present invention are
not necessarily limited to crosslinked foams obtained using the rubber
composition described above. The above crosslinked foams (2) and (3) may
be crosslinked foams obtained using a composition other than the rubber
composition described above as long as they are crosslinked foams satisfying
the above requirements (a) and (b) or requirements (a) and (c). However, the
crosslinked foams (2) and (3) are also preferably obtained using the rubber
composition described above.
[0143]

In the crosslinked foams (2) and (3) of the present invention, their
specific gravity is 0.75 or less, preferably 0.70 or less, more preferably 0.03 to
0.7, and particularly preferably 0.1 to 0.7. This specific gravity is a value
measured according to JIS Z 8807.
[0144]
In the crosslinked foam (2) of the present invention, its elastic modulus
is 3.0 N/mm2 or more, preferably 3.0 to 5.0 N/mm2. This elastic modulus is a
value measured according to JIS E 1117.
[0145]
In the crosslinked foam (3) of the present invention, the average value
of the diameters of voids in the above requirement (c) is 80 µm or less,
preferably 50 to 80 µm.
[0146]
In addition, in the crosslinked foam (1), its specific gravity is preferably
0.03 to 0.9, more preferably 0.1 to 0.8, particularly preferably 0.1 to 0.75, and
most preferably 0.1 to 0.7, its elastic modulus is preferably 3.0 N/mm2 or more,
more preferably 3.0 to 5.0 N/mm2, and the average value of the diameters of
voids in the above requirement (c) is preferably 80 µm or less, more preferably
50 to 80 µm.
[0147]

The railroad rail track pad of the present invention is a molded product
obtained by crosslinking the rubber composition described above, or a molded
product obtained by crosslinking and foaming the rubber composition
described above. In addition, an excellent railroad rail track pad can also be
obtained not only with the crosslinked foam (1) described above but also with

the crosslinked foams (2) and (3) having the particular physical properties
described above.
[0148]
The "railroad rail track pad" means molded products, for example, 1) a
track pad as a railroad component, 2) a rubber sheet used as a track pad, 3) a
rubber crosslinked product used as a track pad, and 4) a rubber crosslinked
foam as a track pad, used for a railroad rail.
Examples
[0149]
The present invention will be described in detail with reference to the
examples. However, the present invention is not limited to these examples.
[0150]

Compositions shown in Table 1 were prepared using the following
copolymers 1 and 2. Using a mold with a size of 125 mm x 140 mm x 10 mmt,
the mold was filled with each composition in Table 1 at a volume filling rate of
100%, and the composition was subjected to primary crosslinking and foaming
under the conditions of 130°C x 15 minutes. Then, using a mold with a size of
200 mm x 200 mm x 1 mmt, the mold was filled with the crosslinked foam
obtained by the primary crosslinking and foaming, and the crosslinked foam
was subjected to secondary crosslinking and foaming under the conditions of
170°C x 10 minutes to produce a foamed and crosslinked product rubber for a
railroad rail track pad. Physical properties were evaluated.
[0151]
(Copolymer 1)

An ethylene-a-olefin-non-conjugated polyene random copolymer
produced by a method similar to that of Example 1 in WO2010/064574 (the
molar ratio difference was adjusted by the amount of feed)
[C-1] = ENB
[C-2] = VNB
Requirement (1): [B] = 36.8 mole%
Requirement (2): [C-1] + [C-2] = 2.91 mole%
Requirement (3): [C-1]/[C-2] = 96/4
Requirement (4): ML1+4 (100°C) = 32
Requirement (5): I V = 0.8 g/100 g
Requirement (6): Ea = 43.0 kJ/mol
[0152]
(Copolymer 2)
An ethylene α-olefin-non-conjugated polyene random copolymer
produced by a method similar to that of Example 1 in WO2010/064574 (the
molar ratio difference was adjusted by the amount of feed)
Ethylene α-olefin-non-conjugated polyene random copolymer
[C-1] = ENB
[C-2] = VNB
Requirement (1): [B] = 40.3 mole%
Requirement (2): [C-1] + [C-2] = 4.47 mole%
Requirement (3): [C-1]/[C-2] = 99/1
Requirement (4): ML1+4 (100°C) = 81
Requirement (5): IV = 0.32 g/100 g
Requirement (6): Ea = 38 kJ/mol
[0153]

Physical properties were evaluated using the urethane rubber of
Example 1 in JP2007-284625A.
[0154]

A composition shown in Table 1 was prepared using the following
copolymer 3. A foamed and crosslinked product rubber for a railroad rail track
pad was produced in the same manner as in Examples 1 and 2. Physical
properties were evaluated.
[0155]
[Copolymer 3]
An ethylene α-olefin-non-conjugated polyene random copolymer
produced by a method similar to that of Comparative Example 4 in
WO2010/064574 (the molar ratio difference was adjusted by the amount of
feed).
[C-1] = ENB (2.3 mole %)
[C-2] = 0 mole %
Requirement (1): [B] = 40.8 mole%
Requirement (2): [C-1] + [C-2] = 2.3 mole%
Requirement (3): [C-1]/[C-2] = 100/0
Requirement (4): ML1+4 (100°C) = 45
Requirement (5): I V = 0 g/100 g
Requirement (6): Ea = 15 kJ/mol
[0156]

(1) The density and specific gravity in the Examples and the

Comparative Examples were measured in conformity to JIS Z 8807. The
elastic modulus was measured in conformity to JIS E 1117. The tensile
strength and elongation were measured in conformity to JIS K 6251. The
compression set was measured in conformity to ASTM D395.
[0157]
(2) Average Value of Diameters of Voids
Each of the samples obtained in the Examples and the Comparative
Examples was cut to an appropriate size, and a cross section of the sample
was observed and photographed at 200x magnification using Digital
Microscope VHX-1000 (manufactured by KEYENCE). Among voids
observed in a fixed area (2.2 cm2) of the cross section of this sample, voids
from a void (cell) having the maximum diameter to a void having the 10th
largest diameter were selected, and the average value of the diameters of
these 10 voids was obtained.
[0158]
The evaluation results are shown in the following Table 1.
[0159]


The numerical values of the compositions in Table 1 are parts by mass.
Active zinc flower: META-ZL40, Lime Industries Co. Ltd. [sic]
FEF carbon black: Asahi #60G, ASAHI CARBON CO., LTD
Silane coupling agent: Si69, Evonik Degussa GmbH
MBT: SANCELER M, SANSHIN CHEMICAL INDUSTRY CO., LTD.
ZBDC: SANCELER BZ, SANSHIN CHEMICAL INDUSTRY CO., LTD.

TMTD: SANCELERTT, SANSHIN CHEMICAL INDUSTRY CO., LTD.
TETD: SANCELER TET-G, SANSHIN CHEMICAL INDUSTRY CO.,
LTD.
ADCA foaming agent: VINYFORAC#3, EIWA CHEMICAL IND. CO.,
LTD.
Foaming aid: CELLPASTE 101, EIWA CHEMICAL IND. CO., LTD.
[0161]

JIS E1117 standard regulates elastic modulus of 3 to 5 N/mm2, tensile
strength of 12 N/mm2 or more, elongation of 250% or more, and compression
set (70°C, 48 h) of 30% or less. Examples 1 and 2 satisfied the standard and
moreover were superior in tensile strength and elongation to Comparative
Example 1 and superior in tensile strength, elongation, and compression set to
Comparative Example 2. Moreover, Examples 1 and 2 also have excellent
processability and therefore are very suitable for railroad rail track pad
applications. Further, in Examples 1 and 2, the average value of the
diameters of voids was smaller than in Comparative Example 2.
[0162]
It is known that generally, when an ethylene α-olefin-non-conjugated
polyene random copolymer with much long chain branching is used, the elastic
modulus tends to decrease. In contrast, in the present invention, on the
contrary, it can be obtained a result that the various properties including an
elastic modulus are improved, due to improve the foaming properties by the
presence of long chain branching. Such a result is an unexpected result for
those skilled in the art.

Industrial Applicability
[0163]
The crosslinked foam of the present invention has a large expansion
ratio, and has required physical properties (including weather resistance), such
as a moderate elastic modulus, high tensile strength and elongation, and small
compression set, and also has excellent processability. Therefore the
crosslinked foam is very suitable for railroad rail track pad applications.

We Claim:
[Claim 1]
A railroad rail track pad obtained by crosslinking a composition
comprising an ethylene α-olefin non-conjugated polyene random copolymer
including structural units derived from ethylene [A], an a-olefin [B] having 3 to
20 carbon atoms, a non-conjugated polyene [C-1], in which only one partial
structure represented by the following general formula (I) or (II) is presented in
one molecule,
[Formula 1]

with the proviso that (I) is a partial structure of a cyclic olefin,
[Formula 2]

and a non-conjugated polyene [C-2], in which two or more partial structures
selected from a group consisting of the formula (I) and (II) are presented in
total in one molecule, wherein the copolymer satisfies conditions of the
following (1)to(6):
(1) the structural units derived from the a-olefin [B] having 3 to 20 carbon
atoms constitute 10 to 50 mole% in 100 mole% of the total structural units,
(2) a sum of the mole% of the structural units derived from the
non-conjugated polyene [C-1] and the mole% of the structural units derived

from the non-conjugated polyene [C-2] is 1.0 to 6.0 mole%,
(3) a ratio of [C-1]/[C-2] in the mole% of the structural unit derived from the
non-conjugated polyene [C-1] to the mole% of the structural unit derived from
the non-conjugated polyene [C-2] is 75/25 to 99.5/0.5,
(4) Mooney viscosity measured at 100°C as [ML1+4 (100°C)] is 10 to 90,
(5) an apparent iodine value (I V) of the structural unit derived from the
non-conjugated polyene [C-2] is 0.1 to 3.0g/100g, and
(6) the following expression (i) is satisfied:
50 > activation energy (Ea) of fluidization [kJ/mol] >35 ••• (i).
[Claim 2]
The railroad rail track pad according to claim 1, wherein the
ethylene α-olefin-non-conjugated polyene random copolymer is synthesized
using a metallocene catalyst.
[Claim 3]
The railroad rail track pad according to claim 1, wherein the
non-conjugated polyene [C-1] is 5-ethylidene-2-norbornene (ENB), and the
non-conjugated polyene [C-2] is 5-vinyl-2-norbomene (VNB).
[Claim 4]
The railroad rail track pad according to claim 1, wherein the
composition is crosslinked with a crosslinking agent.
[Claim 5]
The railroad rail track pad according to claim 1, wherein the
composition is further foamed.
[Claim 6]
The track pad according to claim 1, comprising as a component a
crosslinked foam, wherein

(a) specific gravity of the crosslinked foam is 0.75 or less, and
(b) an elastic modulus of the crosslinked foam is 3.0 N/mm2 or more.
[Claim 7]
The track pad according to claim 1 comprising as a component a
crosslinked foam, wherein
(a) specific gravity of the crosslinked foam is 0.75 or less, and
(c) an average value of diameters of voids from a void having a
maximum diameter to a void having a 10th largest diameter among voids
observed in a fixed area of 2.2 cm2 of a cross section of a molded product is 80
µm or less.
[Claim 8]
A crosslinked foam obtained by crosslinking and foaming a
composition comprising an ethylene α-olefin non-conjugated polyene random
copolymer, wherein
(a) specific gravity of the crosslinked foam is 0.75 or less, and
(b) an elastic modulus of the crosslinked foam is 3.0 N/mm2 or more.
[Claim 9]
A crosslinked foam obtained by crosslinking and foaming a
composition comprising an ethylene α-olefin non-conjugated polyene random
copolymer, wherein
(a) specific gravity of the crosslinked foam is 0.75 or less, and
(c) an average value of diameters of voids from a void having a
maximum diameter to a void having a 10th largest diameter among voids
observed in a fixed area of 2.2 cm2 of a cross section of a molded product is 80
µm or less.