SF-2464 1
DESCRIPTION
Title of Invention:
FOAMING AGENT AND MANUFACTURING METHOD-FORMING AGENT THEREFOR,
5 RUBBER COMPOSITION, CROSS-LINKED FOAM AND MANUFACTURING
METHOD THEREFOR, AND RUBBER MOLDED ARTICLE
Technical Field
[0001]
10 The present invention relates to a foaming agent, a
method for manufacturing a foaming agent and a forming agent
for the foaming agent, a rubber composition, a cross-linked
foam and a manufacturing method therefor, and a rubber molded
article (example: an automobile weather strip sponge, an
15 automobile cushioning material, and an automobile heat
insulating material).
Background Art
[0002]
Hitherto, various foamed materials have been
20 industrially widely produced and sold. Typical examples of
foamed materials include foamed materials of rubber having
both the flexibility and sealing properties. Production of a
foamed material of rubber usually includes a step of crosslinking
and foaming a raw material rubber composition.
SF-2464 2
[0003]
1^ In the above-described foaming, a chemical decomposition
type foaming agent, which generates a gas by decomposition
due to heating, has been used. Known examples of various
5 foaming agents include azodicarbonamide (ADCA), N,N'-
dinitrosopentamethylenetetramine (DPT), and 4,4'-
oxybis(benzenesulfonyl hydrazide) (OBSH) (refer to PTL 1 and
PTL 2, for example).
[0004]
10 However, the chemical decomposition type foaming agent
has problems, such as, inhibition of cross-linking resulting
from a foaming agent, and mold pollution and environmental
pollution caused by a foaming agent residue. In particular,
DPT is a substance which in itself has a risk of explosion or
15 fire and which is suspected of having a possibility of
becoming a mutagen and, therefore, has a drawback that the
safety for a human body is poor. Consequently, development
of an excellent foaming agent which does not have the abovedescribed
problems and which can be used as an alternative to
20 the chemical decomposition type foaming agent has been
desired.
[0005]
Meanwhile, a method for manufacturing a foamed material
of a thermoplastic elastomer by using water as a foaming
SF-2464 3
agent has been known (refer to PTL 3 and PTL 4, for example).
Mb^n these Patent Literatures, the subject of foaming is a
thermoplastic elastomer, and a predetermined foam-molded
material is prepared by pressing water serving as a foaming
5 agent into an extruder.
Citation List
Patent Literature
[0006]
PTL 1: JPA 2000-336337
10 PTL 2: JPA 2001-049020
PTL 3: JPA 1996-216220
PTL 4: JPA 1994-507128
Summary of Invention
Technical Problem
15 [0007]
The present inventors have studied on use of water as a
foaming agent for rubber foaming. However, it was found that
water was not able to be used alone as a foaming agent for
rubber foaming because the uniform dispersibility of water in
20 a raw material rubber composition (unvulcanized rubber) of a
cross-linked rubber material was very low.
[0008]
A first issue of the present invention is to provide an
excellent water foaming agent which does not have problems.
SF-2464 4
such as, risks of handling and operation (example: risk of
l^xplosion or fire) and inhibition of cross-linking resulting
from a foaming agent, and mold pollution and environmental
pollution caused by a foaming agent residue, which has
5 excellent uniform dispersibility in a subject of foaming
(example: raw material rubber composition of cross-linked
rubber material), and which can be used as an alternative to
a chemical decomposition type foaming agent. The issue is
also to provide a rubber composition in which the water
10 foaming agent is uniformly dispersed and which can be foammolded.
[0009]
In this regard, in the case where water is used as the
foaming agent, water has a large evaporation rate, so that it
15 is difficult to control the foaming rate and, in many cases,
outgassing may occur during foaming. (1) For example, in the
case of extrusion foam molding, outgassing from a surface
layer of a molded material occurs easily and, as a result,
the appearance of a cross-linked foam tends to become worse.
20 (2) For example, in the case of in-mold foam molding, rapid
evaporation of water (foaming) occurs easily nearby a mold
and, thereby, it may become difficult to reduce the specific
gravity of the resulting molded material sufficiently
(example: 0.7 or less). (3) For example, in the case of
SF-2464 5
molding, excellent fluidity is required of a rubber
J^composition from the viewpoints of precision moldability and
productivity.
[0010]
5 A second issue of the present invention is to further
improve various performances of a rubber composition
including the water foaming agent in foam molding, e.g.,
extrusion foam molding, the appearance of the resulting
molded material, and the like.
10 [0011]
A third issue of the present invention is to further
improve various performances of a rubber composition
including the water foaming agent in foam molding, e.g., inmold
foam molding, the lightweightness of the resulting
15 molded material, and the like.
[0012]
A fourth issue of the present invention is to further
improve various performances of a rubber composition
including the water foaming agent in molding and the like
20 (example: fluidity in injection and foamability in foam
molding), the appearance of the resulting molded material,
and the like.
Solution to Problem
[0013]
SF-2464 6
The present inventors performed intensive research to
^^olve the above-described issues on the basis of the abovedescribed
findings. As a result, the present inventors have
found that a water foaming agent having the following
5 configuration has excellent uniform dispersibility in a
subject of foaming (example: raw material rubber composition
of cross-linked rubber material) and, therefore, the first
issue is able to be solved. Consequently the present
invention has been completed.
10 [0014]
In addition, the present inventors have found that
rubber compositions having the configurations according to
the items [9] to [11], [12] to [14], and [15] to [17] are,
respectively, able to be favorably subjected to the extrusion
15 foam molding, the in-mold foam molding, the molding, and the
like and, therefore, the second issue, the third issue, and
the fourth issue are able to be solved. Consequently the
present inventions have been completed.
[0015]
20 [1] A foaming agent formed from at least (A) a high
molecular compound having a saturated water absorption of 10
to 1,000 g/g in ion-exchanged water (25°C) and (B) water,
wherein a storage modulus (G') of the agent, determined on
the basis of a viscoelasticity measurement at a temperature
SF-2464 7
of 20°C, is 8.0 X 10^ to 1.0 x 10^ Pa at a frequency of 5
l^rad/s.
[0016]
[2] The foaming agent according to the item [1], wherein
5 the high molecular compound (A) has a saturated water
absorption of 250 to 1,000 g/g in ion-exchanged water (25°C).
[0017]
[3] The foaming agent according to the item [1] or item
[2], which is a foaming agent for rubber foaming.
10 [0018]
[4] The foaming agent according to any one of the items
[1] to [3], wherein the high molecular compound (A) is a
carboxyl group-containing high molecular compound exhibiting
a hydrogel-forming property.
15 [0019]
[5] The foaming agent according to any one of the items
[1] to [4], wherein the water content is 99.85 to 70 percent
by mass.
[0020]
20 [6] A method for manufacturing the foaming agent
according to the item [1], the method including the step of
mixing (A) a high molecular compound having a saturated water
absorption of 10 to 1,000 g/g in ion-exchanged water (25°C)
and (B) water.
SF-2464 8
[0021]
f^ [7] A forming agent for the foaming agent according to
the item [1], including (A) a high molecular compound having
a saturated water absorption of 10 to 1,000 g/g in ion-
5 exchanged water (25°C).
[0022]
[8] A rubber composition including 100 parts by mass of
(I) at least one type of rubber component selected from
natural rubber and synthetic rubber and 0.5 to 300 parts by
10 mass of (II) the foaming agent according to any one of the
items [1] to [5].
[0023]
[9] A rubber composition including 100 parts by mass of
(I-l) an ethylene-a-olefin-nonconjugated polyene random
15 copolymer and 0.5 to 300 parts by mass of (II) the foaming
agent according to any one of the items [1] to [5],
wherein 50 percent by mass or more of the copolymer (I-
1) is a copolymer (X) containing structural units [A] derived
from ethylene, structural units [B] derived from an a-olefin
20 having the carbon number of 3 to 20, structural units [C-1]
derived from a nonconjugated polyene, in which among
carbon*carbon double bonds, only one carbon-carbon double
bond polymerizable with a metallocene catalyst is present in
one molecule, and structural units [C-2] derived from a
SF-2464 9
nonconjugated polyene, in which among the carbon*carbon
J^double bonds, two carbon'carbon double bonds polymerizable
with a metallocene catalyst are present in one molecule, and
satisfying the following requirements (1) to (3),
5 (1) the content of the structural units [B] is 10 to 50
percent by mole in 100 percent by mole of the total
structural units of the copolymer (X),
(2) the total content of the structural units [C-1] and
the structural units [C-2] is 1.0 to 6.0 percent by mole in
10 100 percent by mole of the total structural units of the
copolymer (X), and
(3) the limiting viscosity [TI] measured in a decalin
solution at 135°C is 2.0 to 4.0 dL/g.
[0024]
15 [10] The rubber composition according to the item [9],
wherein in the copolymer (X), at least part of the structural
units [C-1] are structural units derived from 5-ethylidene-2-
norbornene (ENB) and the content of structural units derived
from ENB is 1 to 5 percent by mole in 100 percent by mole of
20 the total structural units of the copolymer (X), and at least
part of the structural units [C-2] are structural units
derived from 5-vinyl-2-norbornene (VNB) and the content of
structural units derived from VNB is 0.01 to 0.45 percent by
mole in 100 percent by mole of the total structural units of
SF-2464 10
the copolymer (X).
||^[0025]
[11] The rubber composition according to the item [9] or
item [10], which is a rubber composition for extrusion foam
5 molding.
[0026]
[12] A rubber composition including 100 parts by mass of
(I-l) an ethylene-a-olefin-nonconjugated polyene random
copolymer and 0.5 to 300 parts by mass of (II) the foaming
10 agent according to any one of the items [1] to [5],
wherein 50 percent by mass or more of the copolymer (I-
1) is a copolymer (Y) containing structural units [A']
derived from ethylene, structural units [B'] derived from an
a-olefin having the carbon number of 3 to 20, structural
15 units [C-1'] derived from a nonconjugated polyene, in which
among carbon-carbon double bonds, only one carbon-carbon
double bond polymerizable with a metallocene catalyst is
present in one molecule, and structural units [C-2'] derived
from a nonconjugated polyene, in which among the
20 carbon-carbon double bonds, two carbon-carbon double bonds
polymerizable with a metallocene catalyst are present in one
molecule, and satisfying the following requirements (4) to
(6),
(4) the content of the structural units [B'] is 10 to 50
SF-2464 11
percent by mole in 100 percent by mole of the total
i^structural units of the copolymer (Y) ,
(5) the total content of the structural units [C-1'] and
the structural units [C-2'] is 1.0 to 6.0 percent by mole in
5 100 percent by mole of the total structural units of the
copolymer (Y), and
(6) the limiting viscosity [r\] measured in a decalin
solution at 135°C is 0.8 to 1,8 dL/g.
[0027]
10 [13] The rubber composition according to the item [12],
wherein in the copolymer (Y), at least part of the structural
units [C-1'] are structural units derived from 5-ethylidene-
2-norbornene (ENB) and the content of structural units
derived from ENB is 1 to 5 percent by mole in 100 percent by
15 mole of the total structural units of the copolymer (Y), and
at least part of the structural units [C-2'] are structural
units derived from 5-vinyl-2-norbornene (VNB) and the content
of structural units derived from VNB is 0.01 to 0.45 percent
by mole in 100 percent by mole of the total structural units
20 of the copolymer (Y).
[0028]
[14] The rubber composition according to the item [12]
or item [13], which is a rubber composition for in-mold foam
molding.
SF-2464 12
[0029]
^. [15] A rubber composition including 100 parts by mass of
(I-l) an ethylene-a-olefin-nonconjugated polyene random
copolymer and 0.5 to 300 parts by mass of (II) the foaming
5 agent according to any one of the items [1] to [5],
wherein 10 to 50 percent by mass of the copolymer (I-l)
is a copolymer (X) containing structural units [A] derived
from ethylene, structural units [B] derived from an a-olefin
having the carbon number of 3 to 20, structural units [C-1]
10 derived from a nonconjugated polyene, in which among
carbon*carbon double bonds, only one carbon-carbon double
bond polymerizable with a metallocene catalyst is present in
one molecule, and structural units [C-2] derived from a
nonconjugated polyene, in which among the carbon-carbon
15 double bonds, two carbon-carbon double bonds polymerizable
with a metallocene catalyst are present in one molecule, and
satisfying the following requirements (1) to (3), and
wherein 90 to 50 percent by mass of the copolymer (I-l)
is a copolymer (Y) containing structural units [A'] derived
20 from ethylene, structural units [B'] derived from an a-olefin
having the carbon number of 3 to 20, structural units [C-1']
derived from a nonconjugated polyene, in which among
carbon-carbon double bonds, only one carbon-carbon double
bond polymerizable with a metallocene catalyst is present in
SF-2464 13
one molecule, and structural units [C-2'] derived from a
Jfci. nonconjugated polyene, in which among the carbon-carbon
double bonds, two carbon-carbon double bonds polymerizable
with a metallocene catalyst are present in one molecule, and
5 satisfying the following requirements (4) to (6),
(1) the content of the structural units [B] is 10 to 50
percent by mole in 100 percent by mole of the total
structural units of the copolymer (X),
(2) the total content of the structural units [C-1] and
10 the structural units [C-2] is 1,0 to 6.0 percent by mole in
100 percent by mole of the total structural units of the
copolymer (X),
(3) the limiting viscosity [r\] measured in a decalin
solution at 135°C is 2.0 to 4.0 dL/g,
15 (4) the content of the structural units [B'] is 10 to 50
percent by mole in 100 percent by mole of the total
structural units of the copolymer (Y),
(5) the total content of the structural units [C-1'] and
the structural units [C-2'] is 1.0 to 6.0 percent by mole in
20 100 percent by mole of the total structural units of the
copolymer (Y), and
(6) the limiting viscosity [r\] measured in a decalin
solution at 135°C is 0.8 to 1.8 dL/g.
[0030]
SF-2464 14
[16] The rubber composition according to the item [15],
A^wherein in the copolymer (X), at least part of the structural
units [C-1] are structural units derived from 5-ethylidene-2-
norbornene (ENB) and the content of structural units derived
5 from ENB is 1 to 5 percent by mole in 100 percent by mole of
the total structural units of the copolymer (X), and at least
part of the structural units [C-2] are structural units
derived from 5-vinyl-2-norbornene (VNB) and the content of
structural units derived from VNB is 0.01 to 0.45 percent by
10 mole in 100 percent by mole of the total structural units of
the copolymer (X), and in the copolymer (Y), at least part of
the structural units [C-1'] are structural units derived from
5-ethylidene-2-norbornene (ENB) and the content of structural
units derived from ENB is 1 to 5 percent by mole in 100
15 percent by mole of the total structural units of the
copolymer (Y), and at least part of the structural units [C-
2'] are structural units derived from 5-vinyl-2-norbornene
(VNB) and the content of structural units derived from VNB is
0.01 to 0.45 percent by mole in 100 percent by mole of the
20 total structural units of the copolymer (Y).
[0031]
[17] The rubber composition according to the item [15]
or item [16], which is a rubber composition for molding.
[0032]
SF-2464 15
[18] The rubber composition according to any one of the
A items [8] to [17], further including a cross-linking agent.
[0033]
[19] A cross-linked foam produced by cross-linking foam
5 molding the rubber composition according to any one of the
items [8] to [18].
[0034]
[20] A rubber molded article including the cross-linked
foam according to the item [19].
10 [0035]
[21] An automobile weather strip sponge, an automobile
cushioning material, or an automobile heat insulating
material including the cross-linked foam according to the
item [19].
15 [0036]
[22] A method for manufacturing a cross-linked foam,
including the steps of extruding the rubber composition
according to any one of the items [9] to [11] by an extrusion
molding method and heating the resulting extrusion molded
20 material to induce cross-linking and foaming.
[0037]
[23] A method for manufacturing a cross-linked foam,
including a first foaming step to fill the rubber composition
according to any one of the items [12] to [14] into a primary
SF-2464 16
mold, perform heating under pressure and, subsequently,
•^ reduce the pressure to induce foaming and a second foaming
step to put the primary foamed material obtained by the first
foaming step into a secondary mold and perform heating at
5 normal pressure to induce foaming.
[0038]
[24] A method for manufacturing a cross-linked foam
including the steps of injecting the rubber composition
according to any one of the items [15] to [17] into a mold by
10 a molding method and performing heating in the mold to induce
cross-linking and foaming.
Advantageous Effects of Invention
[0039]
According to the present invention, it is possible to
15 provide an excellent water foaming agent which does not have
problems, such as, risks of handling and operation (example:
risk of explosion or fire) and inhibition of cross-linking
resulting from a foaming agent, and mold pollution and
environmental pollution caused by a foaming agent residue,
20 which has excellent uniform dispersibility in a subject of
foaming (example: raw material rubber composition of crosslinked
rubber material), and which can be used as an
alternative to the chemical decomposition type foaming agent.
It is also possible to provide a rubber composition in which
SF-2464 17
the water foaming agent is uniformly dispersed and which can
^ be foam-molded.
[0040]
According to the items [9] to [11] of the present
5 invention, it is possible to provide a rubber composition
including a specific water foaming agent, wherein even in the
case of, for example, extrusion foam molding, outgassing from
a surface layer of a molded material is suppressed and a
cross-linked foam having excellent appearance can be obtained,
10 [0041]
According to the items [12] to [14] of the present
invention, it is possible to provide a rubber composition
including a specific water foaming agent, wherein in the case
of, for example, in-mold foam molding, outgassing is
15 suppressed during foaming, and a cross-linked foam having a
sufficiently small specific gravity (example: 0.7 or less)
can be obtained.
[0042]
According to the items [15] to [17] of the present
20 invention, it is possible to provide a rubber composition
including a specific water foaming agent, wherein excellent
fluidity is exhibited, and in the case of, for example,
molding, cross-linked foam exhibiting excellent appearance of
an end portion surface can be obtained, while outgassing is
SF-2464 18
suppressed during foaming.
gi| Brief Description of Drawings
[0043]
[Fig. 1] Fig. 1 is a schematic diagram of a mold used in
5 production of a tube-shaped sponge in an example.
Description of Embodiments
[0044]
The present invention will be described below in detail.
[0045]
10 [Foaming agent]
A foaming agent according to the present invention is
formed from at least (A) a high molecular compound having a
saturated water absorption of 10 to 1,000 g/g in ionexchanged
water (25°C) and (B) water and has a specific
15 storage modulus (G'). In this regard, hereafter the foaming
agent according to the present invention may be referred to
as "Foaming agent A", and the individual components may be
referred to as "High molecular compound (A)" and "Water (B)",
respectively.
20 [0046]
The storage modulus (G') at a frequency of 5 rad/s of
Foaming agent A determined on the basis of a viscoelasticity
measurement at a temperature of 20°C is 8.0 x lO'"' to 1.0 x 10^
Pa, preferably 8.0 x 10^ to 8.0 x 10^ Pa, and more preferably
SF-2464 19
1.0 X 10^ to 5,0 X 10^ Pa. The detailed measurement condition
^ of the storage modulus (C) is as described in the examples.
[0047]
The storage modulus (C) of Foaming agent A falls within
5 the range. Therefore, Foaming agent A has excellent uniform
dispersibility in a raw material rubber composition of a
cross-linked rubber material. If the storage modulus (C)
exceeds the range, the foaming agent becomes a foreign matter
in the raw material rubber composition and may cause
10 significant degradation in the appearance. If the storage
modulus (C) is less than the range, the foaming agent is not
easily uniformly dispersed into the raw material rubber
composition and defective foaming (irregular foaming or the
like) may be induced.
15 [0048]
In the present invention, a term "cross-linked rubber"
refers to rubber which has been cross-linked. A term "raw
material rubber composition of a cross-linked rubber
material" refers to a crude rubber composition before being
20 cross-linked, which exhibits rubber elasticity after being
cross-linked, and may be simply referred to as "rubber
composition".
[0049]
The water content of Foaming agent A is preferably 99.85
SF-2464 20
to 70 percent by mass, more preferably 99.8 to 75 percent by
^ mass, further preferably 99.8 to 80 percent by mass,
particularly preferably 99.8 to 90.0 percent by mass, and
most preferably 99.8 to 99.0 percent by mass. The water
5 content is determined from, for example, a blending ratio of
High molecular compound (A) to Water (B), and details thereof
are as described in the examples.
[0050]
In the case where the water content is within the range,
10 the balance between the handleability of the foaming agent
and the amount of generation of gas is excellent. If the
water content is more than the range, the amount of
generation of gas is small in relation to the mass, large
amounts of foaming agent is required, and degradation in the
15 properties may be induced. If the water content is less than
the range, the handleability of the foaming agent in itself
may be degraded.
[0051]
In Foaming agent A according to the present invention,
20 High molecular compound (A) is usually in the state of gel
because of Water (B). Therefore, Foaming agent A usually has
a hydrogel type structure.
[0052]
According to the studies of the preset inventors, water
SF-2464 21
is hardly dispersed into the raw material rubber composition
g^ of a cross-linked rubber material and it has been very
difficult to use water as a foaming agent for rubber foaming.
[0053]
5 However, in the present invention, water is used in a
special state, that is, a form of the above-described foaming
agent. The present inventors have found that the foaming
agent concerned has excellent uniform dispersibility in the
raw material rubber composition of a cross-linked rubber
10 material and, as a result, the uniform dispersibility of
water in the raw material rubber composition of a crosslinked
rubber material is improved considerably.
[0054]
Therefore, Foaming agent A (water contained in A
15 concerned) is very suitable for the foaming agent for rubber
foaming. Examples of advantages thereof include that (1)
there is no risk of explosion or fire in handling and
operation, (2) a foamed material having excellent properties
(example: compressive stress) is obtained because there is no
20 inhibition of cross-linking resulting from a foaming agent,
and (3) there is no mold pollution and environmental
pollution caused by a foaming agent residue because water
having no staining property is used as a foaming agent and
use of a chemical decomposition type foaming agent can be
SF-2464 22
reduced,
y [0055]
Meanwhile, the shape of Foaming agent A is not
specifically limited and may be selected appropriately in
5 accordance with the use thereof (example: uses of rubber
composition including Foaming agent A) and the production
condition. For example, a massive shape is mentioned.
[0056]

10 The saturated water absorption of High molecular
compound (A) in ion-exchanged water (25°C) is 10 to 1,000 g/g,
preferably 20 to 1,000 g/g, more preferably 50 to 1,000 g/g,
further preferably 250 to 1,000 g/g, and most preferably 300
to 1,000 g/g. The detailed measurement condition of the
15 saturated water absorption is as described in the examples.
[0057]
In the case where the saturated water absorption of High
molecular compound (A) is within the range. Foaming agent A
exhibits excellent water retentivity. Consequently, when the
20 foaming agent concerned is dispersed into the raw material
rubber composition of a cross-linked rubber material,
favorably, water is not released. In particular, it is
favorable that the saturated water absorption of High
molecular compound (A) is 250 g/g or more because the
SF-2464 23
dispersibility of the foaming agent in the raw material
Jg rubber composition of a cross-linked rubber material is
improved.
[0058]
5 The shape of High molecular compound (A) in preparation
of Foaming agent A is not specifically limited and may be
selected appropriately in accordance with the use of the
foaming agent. For example, particulate shapes are mentioned,
Among them, particles having a weight average particle
10 diameter of 200 to 10,000 |jjn are preferable.
Examples of High molecular compounds (A) include high
molecular compounds having a cross-linked structure and/or a
network structure and having a property capable of forming
hydrogel by holding water on the basis of the structure
15 concerned (in the inside thereof), that is, high molecular
compounds exhibiting a hydrogel-forming property. The term
"hydrogel" refers to gel including at least a cross-linked
structure and/or a network structure formed from a high
molecular compound and water supported and/or held in the
20 structure concerned.
[0059]
The water is not specifically limited insofar as the
water is supported and/or held as a liquid (liquid
dispersion), which contains water as a primary component, in
SF-2464 24
a cross-linked structure and/or a network structure.
Ac Examples of liquid dispersion include water in itself
(example: pure water, e.g., distilled water and ion-exchanged
water, and service water), aqueous solutions, and water-
5 containing liquids (example: mixed liquids of water and
monohydric or polyhydric alcohol and the like).
[0060]
As for High molecular compound (A), from the viewpoint
of water solubility or hydrophilicity, preferably high
10 molecular compounds having an acid group and/or a salt
thereof are mentioned, more preferably high molecular
compounds having at least one type of functional group
selected from a carboxyl group, an acid anhydride group, a
sulfo group, a phosphate group and salts thereof (example:
15 alkali metal salts, e.g., Na salts and K salts, and ammonium
salts) are mentioned, and further preferably carboxyl groupcontaining
high molecular compounds are mentioned.
[0061]
In this regard, if the acidity of High molecular
20 compound (A) is too high, inhibition of cross-linking may
occur. Therefore, the pH of High molecular compound (A) (1 g
of High molecular compound (A) is dispersed into 100 mL of
ion-exchanged water, and a measurement is performed after
standing for 1 hour) is preferably 4 to 9, more preferably
SF-2464 25
4.5 to 8.5, and further preferably 5 to 8.
^ [0062]
Examples of methods for preparing High molecular
compound (A) include (1) a method which includes polymerizing
5 a polymerizable monomer in the presence of a copolymerizable
cross-linking agent, so as to introduce a cross-linked
structure, and (2) a method which includes subjecting a
polymer obtained by polymerizing the polymerizable monomer or
a known water-soluble or hydrophilic high molecular compound
10 is subjected to a post-cross-linking treatment, so as to
introduce a cross-linked structure. The method (1) is
preferable as the method for preparing High molecular
compound (A) because of ease in controlling the degree of
polymerization and cross-linking density thereof. In
15 addition, polysaccharide, polyvinyl alcohol, or the like can
also be used as High molecular compound (A).
[0063]
«Method (1)»
Examples of polymerizable monomers (where
20 copolymerizable cross-linking agents described later are not
included in the polymerizable monomers) include polymerizable
monomers having an acid group. As for the polymerizable
monomers, polymerizable monomers other than the polymerizable
monomers having an acid group can also be mentioned.
SF-2464 26
[0064]
^^ Examples of polymerizable monomers having an acid group
include polymerizable monomers having a carboxyl group, e.g.,
(meth)acrylic acid, crotonic acid, sorbic acid, maleic acid,
5 itaconic acid, and cinnamic acid; polymerizable monomers
having an acid anhydride group, e.g., maleic anhydride;
polymerizable monomers having a sulfo group, e.g., vinyl
sulfonic acid, allyl sulfonic acid, styrene sulfonic acid,
vinyltoluene sulfonic acid, 2-(meth)acrylamide-2-
10 methylpropane sulfonic acid, 2-(meth)acryloylethane sulfonic
acid, and 2-(meth)acryloylpropane sulfonic acid; and
polymerizable monomers having a phosphate group, e.g., 2-
hydroxyethylacryloyl phosphate, 2-hydroxyethylmethacryloyl
phosphate, phenyl-2-acryloyloxyethyl phosphate, and vinyl
15 phosphoric acid. Among them, from the viewpoints of
polymerizability and neutralizability, polymerizable monomers
having a carboxyl group and polymerizable monomers having a
sulfo group are preferable, polymerizable monomers having a
carboxyl group are more preferable, and acrylic acid is
20 particularly preferable.
[0065]
One type of the polymerizable monomers having an acid
group may be used alone, or at least two types may be used in
combination. The polymerizable monomers having an acid group
SF-2464 27
may be polymerized in the form of a salt thereof (example:
^1^ alkali metal salts, e.g., Na salts and K salts, and ammonium
salts), or a salt may be produced by neutralizing acid groups
partly after polymerization.
5 [0066]
Examples of other polymerizable monomers include alkyl
or alkylene oxide ester of unsaturated carboxylic acids
(example: (meth)acrylic acid, crotonic acid, sorbic acid,
maleic acid, itaconic acid, and cinnamic acid), e.g., methyl
10 (meth)acrylate, ethyl (meth)acrylate, methoxypolyethylene
glycol (meth)acrylate, and polyethylene glycol
mono(meth)acrylate; aromatic vinyl hydrocarbons, e.g.,
styrene; aliphatic vinyl hydrocarbons, e.g., ethylene,
propylene, and butene; unsaturated nitrile compounds, e.g.,
15 acrylonitrile; and unsaturated amide compounds, e.g.,
acrylamide, methacrylamide, N-isopropylacrylamide, and Nvinylacetamide.
[0067]
One type of the other polymerizable monomers may be used
20 alone, or at least two types may be used in combination.
[0068]
Examples of copolymerizable cross-linking agents include
(1) compounds having at least two polymerizable double bonds
(Copolymerizable cross-linking agent (1)) and (2) compounds
SF-2464 28
having at least one polymerizable double bond and at least
^^ one functional group capable of reacting with the functional
group (example: acid group) of the polymerizable monomer
(Copolymerizable cross-linking agent (2)).
5 [0069]
Examples of Copolymerizable cross-linking agents (1)
include N,N'-methylenebis(meth)acrylamide, N,N'-
ethylenebis(meth)acrylamide, ethylene glycol di(meth)acrylate,
polyethylene glycol di(meth)acrylate, propylene glycol
10 di(meth)acrylate, polypropylene glycol di(meth)acrylate,
trimethylolpropane di(meth)acrylate, trimethylolpropane
tri(meth)acrylate, ethylene oxide-modified trimethylolpropane
tri(meth)acrylate, glycerol acrylate methacrylate, glycerol
tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,
15 dipentaerythritol hexa(meth)acrylate, triallyl cyanurate,
triallyl isocyanurate, triallyl phosphate, triallylamine,
poly(meth)allyloxyalkane, divinylbenzene, divinyltoluene,
divinylxylene, divinylnaphthalene, divinyl ether, divinyl
ketone, trivinylbenzene, tolylene diisocyanate, and
20 hexamethylene diisocyanate.
[0070]
Examples of Copolymerizable cross-linking agents (2)
include compounds having an epoxy group and a polymerizable
double bond in the molecule, e.g., glycidyl (meth)acrylate;
SF-2464 29
compounds having a hydroxy group and a polymerizable double
^^bond in the molecule, e.g., N-methylol (meth)acrylamide; and
primary to quaternary amino group-containing unsaturated
compounds, e.g., N,N,N-trimethyl-N-
5 (meth)acryloyloxyethyltrimethylammonium chloride, N,N,Ntriethyl-
N-(meth)acryloyloxyethyltrimethylammonium chloride,
dimethylaminoethyl (meth)acrylate, diethylaminoethyl
(meth)acrylate, allylamine, and vinyl pyridine.
[0071]
10 Among the copolymerizable cross-linking agents, N,N'-
methylenebisacrylamide is preferable.
[0072]
Copolymerizable cross-linking agents may be used alone,
or at least two types may be used in combination.
15 [0073]
The usage of the copolymerizable cross-linking agent is
usually 0.01 to 10 parts by mass, and preferably 0.1 to 5
parts by mass relative to 100 parts by mass of the
polymerizable monomer. If the usage of the copolymerizable
20 cross-linking agent is less than the range, the mechanical
strength of High molecular compound (A) may become low and
handling may become difficult. If the usage is more than the
range, the saturated water absorption may be reduced.
[0074]
SF-2464 30
«Method (2)»
^^ Examples of methods usable as the method of the item (2)
include a method in which a cross-linked structure is
introduced in between polymer molecules by a heat treatment;
5 a method in which a cross-linked structure is introduced in
between polymer molecules by application of light, electron
beams, y^^ys? or the like; and a method in which a crosslinked
structure is introduced in between the polymer
molecules by using a polyfunctional molecule having in the
10 molecule a plurality of functional groups (example: epoxy
group, hydroxyl group, and amino group), which can react with
the functional group (example: acid group) in the polymer, as
a cross-linking agent.
[0075]
15 Examples of polyfunctional molecules include
polyethylene glycol diglycidyl ether, glycerol diglycidyl
ether, ethylene glycol, polyethylene glycol, propylene glycol,
glycerin, pentaerythritol, ethylenediamine, polyethyleneimine,
and ethylene carbonate.
20 [0076]
Examples of polymers obtained by polymerizing the
polymerizable monomers include polymers obtained by
polymerizing the polymerizable monomers described in the
above-described «Method (1)» as examples, specifically.
SF-2464 31
polyacrylic acid, polymethacrylic acid, polyvinyl sulfonic
Jm, acid, polystyrene sulfonic acid, and salts thereof (example:
alkali metal salts, e.g., Na salts and K salts, and ammonium
salts).
5 [0077]
Examples of water-soluble or hydrophilic high molecular
compounds include polysaccharides, e.g., methyl cellulose,
dextran; polyethylene oxide, polypropylene oxide, polyvinyl
alcohol, polyN-vinylpyrrolidone, polyN-vinylacetamide,
10 polyvinylpyridine, polyacrylamide, polymethacrylamide, poly-
N-acryloylpiperidine, poly-N-n-propyl methacrylamide, poly-Nisopropylacrylamide,
poly-N,N-diethylacrylamide, poly-Nisopropyl
methacrylamide, poly-N-cyclopropylacrylamide, poly-
N-acryloylpyrrolidine, poly-N,N-ethylmethylacrylamide, poly-
15 N-cyclopropyl methacrylamide, poly-N-ethylacrylamide, poly-Nmethylacrylamide,
polyhydroxymethyl acrylate; polyN,Ndimethylaminoethyl
methacrylate, polyN,N-diethylaminoethyl
methacrylate, polyN,N-dimethylaminopropylacrylamide, and
salts thereof.
20 [0078]
«Polymerization method>>
The polymerization method is not specifically limited
and previously known methods are mentioned. Examples include
a solution polymerization method in which the polymerizable
SF-2464 32
monomer, the copolymerizable cross-linking agent, and a
^ polymerization initiator are dissolved into water or an
aqueous liquid (example: water, methanol, ethanol, acetone,
N,N-dimethylformamide, dimethyl sulfoxide, methyl ethyl
5 ketone, and mixtures of at least two types thereof) and the
monomer and the like are polymerized with heat, light,
electron beams, or the like; and a bulk polymerization method
in which in the case where the polymerizable monomer is a
liquid, the copolymerizable cross-linking agent and a
10 polymerization initiator are added to the polymerizable
monomer, and the monomer and the like are bulk-polymerized
with heat, light, electron beams, or the like. In addition,
an emulsion polymerization method, a suspension
polymerization method, a precipitation polymerization method,
15 and the like can be used. The thus obtained polymer is dried
appropriately and, thereby. High molecular compound (A) can
be obtained.
[0079]
As for High molecular compound (A), commercially
20 available products can also be used. Examples of the abovedescribed
commercially available products include Sky Gel
(produced by Mebiol Inc.), SANFRESH (produced by Sanyo
Chemical Industries, Ltd.), ACRYHOPE (produced by NIPPON
SHOKUBAI CO., LTD.), and Fujimihuresshu (in Japanese)
SF-2464 33
(produced by Fujimiryokka Co., Ltd.).
^ [0080]
«Adjustment of saturated water absorption»
The saturated water absorption of High molecular
5 compound (A) can be adjusted by, for example, changing the
type or the cross-linking density of High molecular compound
(A) . The saturated water absorption of High molecular
compound (A) tends to depend on the cross-linked structure,
especially the cross-linking density and, in general, the
10 saturated water absorption tends to increase as the crosslinking
density becomes low.
[0081]
An adjustment to a predetermined cross-linking density
can be performed by, for example, changing the usage of the
15 copolymerizable cross-linking agent in the method according
to the item (1) and by, for example, changing irradiance
level of light, electron beams, y-rays, or the like in the
method according to the item (2).
[0082]
20 «Forming agent for foaming agent»
As described above. High molecular compound (A) is a
forming agent for Foaming agent A. That is, the forming
agent for the foaming agent A includes High molecular
compound (A) . The forming agent for the foaming agent A may
SF-2464 34
include additives, as necessary. Examples of additives
^ include an antioxidant and an antiseptic.
[0083]

5 It is believed that in Foaming agent A, High molecular
compound (A) is made into hydrogel by Water (B). Foaming
agent A usually takes on the form of gel. Water (B) is not
specifically limited insofar as Water (B) is included as a
liquid (liquid dispersion), which contains water as a primary
10 component, in Foaming agent A. Examples of liquid dispersion
include water in itself (example: pure water, e.g., distilled
water and ion-exchanged water, and service water), aqueous
solutions, and water-containing liquids (example: mixed
liquids of water and monohydric or polyhydric alcohol and the
15 like). As for Foaming agent A, Water (B) uniformly dispersed
in a subject is evaporated by heating and, thereby, the
subject is foamed.
[0084]
[Method for manufacturing Foaming agent A]
20 Foaming agent A can be produced by, for example, mixing
High molecular compound (A) and Water (B) at room temperature
(25°C) and standing for about 1 hour while stirring is
performed sometimes. The usage of them is selected
appropriately in such a way that predetermined properties are
SF-2464 35
obtained. In production of Foaming agent A, the amount of
AK blend of Water (B) is usually 200 to 70,000 parts by mass,
preferably 300 to 50,000 parts by mass, more preferably 400
to 50,000 parts by mass, further preferably 900 to 50,000
5 parts by mass, and particularly preferably 10,000 to 50,000
parts by mass relative to 100 parts by mass of High molecular
compound (A), If the amount of blend of Water (B) increases,
the storage modulus (C) usually decreases. If the amount of
blend of Water (B) decreases, the storage modulus (C)
10 usually increases.
[0085]
In production of Foaming agent A, besides High molecular
compound (A) and Water (B), additives may be blended, as
necessary. Examples of additives include an antioxidant and
15 an antiseptic.
[0086]
[Use of Foaming agent A (subject of foaming)]
As described above. Foaming agent A is especially
favorably used as a foaming agent for foaming rubber.
20 Examples of raw material rubber include natural rubber and
synthetic rubber. Examples of synthetic rubber include
ethylene-propylene-diene copolymer rubber (EPDM), nitrile
rubber (NBR), butadiene rubber (BR), styrene-butadiene rubber
(SBR), chloroprene rubber (CR), butyl rubber (IIR),
SF-2464 36
chlorinated butyl rubber (CIIR), brominated butyl rubber
^ (BUR), isoprene rubber (IR), and acrylic rubber (ACM).
Among them, from the viewpoints of foamability and properties
of foamed material, Foaming agent A is favorably used as a
5 foaming agent for natural rubber, EPDM, BR, SBR, CR, and IIR.
[0087]
In addition. Foaming agent A can also be used as a
foaming agent for foaming materials other than rubber.
Examples of subjects of foaming include plastics, such as,
10 vinyl chloride resin, vinyl chloride copolymer resin;
polyolefin copolymer resin, e.g., polyethylene, polypropylene,
ethylene-vinyl acetate copolymer resin; ABS resin, and
polycarbonate resin.
[0088]
15 In this regard, specific uses of Foaming agent A are
referred to an item [Foamed material] described later.
[0089]
The operating temperature (foaming temperature) of
Foaming agent A is not specifically limited insofar as the
20 temperature is higher than or equal to the evaporation
temperature of water. For example, 100°C to 300°C is
preferable at normal pressure from the viewpoint of
proportion to the cross-linking reaction.
[0090]
SF-2464 37
[Rubber composition]
^ The rubber composition according to the present
invention includes (1) at least one type of rubber component
selected from natural rubber and synthetic rubber, (A) a high
5 molecular compound having a saturated water absorption of 10
to 1,000 g/g in ion-exchanged water (25°C), and (B) water.
Hereafter the rubber component may be referred to as "Rubber
component (I)".
[0091]
10 In the rubber composition. Water (B) is uniformly
dispersed in Rubber component (I) because High molecular
compound (A) is present. As described above, it is estimated
that Water (B) forms hydrogel together with High molecular
compound (A) and, thereby, the dispersibility of Water (B) in
15 Rubber component (I) is improved. The rubber composition has
excellent workability in a kneading machine, extrusion
moldability, in-mold moldability, injection moldability, and
the like.
[0092]
20 The rubber composition according to the present
invention is obtained by, for example, mixing Rubber
component (I) and Foaming agent A (hereafter may be referred
to as "Foaming agent (II)") described above. That is,
preferably. High molecular compound (A) and Water (B) are
SF-2464 38
components derived from Foaming agent (II) . That is,
A preferably, the rubber composition according to the present
invention includes Rubber component (I) and Foaming agent
(II) .
5 [0093]
A rubber composition according to a first embodiment of
the present invention includes at least an ethylene-aolefin*
nonconjugated polyene random copolymer (I-l) as Rubber
component (I), wherein 50 percent by mass or more of the
10 copolymer (I-l) is a copolymer (X) described later.
[0094]
A rubber composition according to a second embodiment of
the present invention includes at least an ethylene•aolefin-
nonconjugated polyene random copolymer (I-l) as Rubber
15 component (I), wherein 50 percent by mass or more of the
copolymer (I-l) is a copolymer (Y) described later.
[0095]
A rubber composition according to a third embodiment of
the present invention includes at least an ethylene-a-
20 olefin-nonconjugated polyene random copolymer (I-l) as Rubber
component (I), wherein 10 to 50 percent by mass of the
copolymer (I-l) is a copolymer (X) and 90 to 50 percent by
mass is a copolymer (Y).
[0096]
SF-2464 39
The rubber composition according to the first embodiment
of the present invention has excellent workability in a
kneading machine and extrusion foam moldability. The rubber
composition according to the second embodiment of the present
5 invention has excellent workability in a kneading machine and
in-mold foam moldability. The rubber composition according
to the third embodiment of the present invention has
excellent workability in a kneading machine and moldability.
[0097]
10 Meanwhile, in the case of, for example, extrusion foam
molding, molding is performed under the pressureless
condition and, therefore, even a small amount of evaporation
of water causes outgassing from a surface layer of a molded
material, so as to degrade the appearance. In order to
15 suppress outgassing to stabilize generated foam cells,
formation of an appropriate network structure is effective.
Consequently, it is important to control the primary
structure (in particular branch structure) and the crosslinking
reactivity of the copolymer constituting the network
20 structure in such a way that a good balance is ensured
between the cross-linking rate and the evaporation rate of
water.
[0098]
In the rubber composition according to the first
SF-2464 40
embodiment of the present invention, the ethylene-a-
0^ olefin-nonconjugated polyene random copolymer (I-l),
especially the specific ethylene-a-olefin*nonconjugated
polyene random copolymer (X) is used as the rubber component.
5 Therefore, it is believed that the balance is excellent in
extrusion foam molding and, thereby, a cross-linked foam
having excellent appearance and lightweightness can be
obtained.
[0099]
10 Meanwhile, in the case of, for example, in-mold foam
molding, evaporation (foaming) of water occurs rapidly on the
surface in contact with the mold and a portion nearby the
mold, so as to induce outgassing. As a result, there is a
tendency of the specific gravity of a molded material not to
15 decrease sufficiently. In order to suppress outgassing in
the vicinity of the mold to stabilize generated foam cells,
formation of an appropriate network structure is effective.
Consequently, it is important to control the primary
structure (in particular branch structure) and the cross-
20 linking reactivity of the copolymer constituting the network
structure in such a way that a good balance is ensured
between the cross-linking rate and the evaporation rate of
water,
[0100]
SF-2464 41
In the rubber composition according to the second
t embodiment of the present invention, the ethylene-aolefin-
nonconjugated polyene random copolymer (I-l),
especially the specific ethylene-a-olefin-nonconjugated
5 polyene random copolymer (Y) is used as the rubber component.
Therefore, it is believed that the balance is excellent in
foam molding and, thereby, a cross-linked foam having
excellent lightweightness can be obtained.
[0101]
10 Meanwhile, in the case of, for example, molding, the
fluidity of the rubber composition is important and, in
addition, outgassing from a surface layer of a molded
material is caused by even a small amount of evaporation of
water at a molded material end portion which is a portion
15 relatively not applied with a pressure easily during molding.
As a result, degradation of the appearance is induced and, in
addition, there is a tendency of the specific gravity not to
decrease sufficiently. In order to suppress outgassing to
stabilize generated foam cells, formation of an appropriate
20 network structure is effective. Consequently, it is
important to control the primary structure (in particular
branch structure) and the cross-linking reactivity of the
copolymer constituting the network structure in such a way
that a good balance is ensured between the cross-linking rate
SF-2464 42
and the evaporation rate of water.
m, [0102]
In the rubber composition according to the third
embodiment of the present invention, the ethylene-a-
5 olefin-nonconjugated polyene random copolymer (I-l),
especially the specific ethylene'a-olefin-nonconjugated
polyene random copolymer (X) and copoloymer (Y) are used in
combination as the rubber component. Therefore, it is
believed that the fluidity and the balance is excellent in
10 molding and, thereby, a cross-linked foam having excellent
appearance of the end portion surface and lightweightness can
be obtained.
[0103]

15 Examples of Rubber component (I) include raw material
rubber, e.g., natural rubber and synthetic rubber, that is,
at least one type of rubber selected from the natural rubber
and the synthetic rubber.
[0104]
20 Examples of synthetic rubber include ethylene• aolefin-
nonconjugated polyene random copolymers (I-l), e.g.,
ethylene•propylene•diene copolymer rubber (EPDM), nitrile
rubber (NBR), butadiene rubber (BR), styrene•butadiene rubber
(SBR), chloroprene rubber (CR), butyl rubber (IIR),
SF-2464 43
chlorinated butyl rubber (CIIR), brominated butyl rubber
^ (BUR), isoprene rubber (IR), and acrylic rubber (ACM).
[0105]
Among them, natural rubber, ethylene-a-
5 olefin-nonconjugated polyene random copolymer (I-l), e.g.,
EPDM, BR, SBR, CR, and IIR are preferable from the viewpoints
of foamability and properties of foamed material.
[0106]
The rubber composition according to the present
10 invention includes Rubber component (I), preferably includes
the ethylene-a-olefin*nonconjugated polyene random copolymer
(I-l), and particularly preferably rubber compositions
according to the first to third embodiments including the
following specific copolymer.
15 [0107]
The rubber composition according to the first embodiment
of the present invention includes the ethylene-aolefin*
nonconjugated polyene random copolymer (I-l), and 50
percent by mass or more, preferably 60 percent by mass or
20 more, and particularly preferably 70 percent by mass or more
of the copolymer (I-l) is a specific ethylene-aolefin-
nonconjugated polyene random copolymer (X) described
below. Use of the copolymer (X) within the range exerts an
effect in obtaining an extrusion cross-linked foam exhibiting
SF-2464 44
excellent compression set property and lightweightness and
having small surface roughness and good molded material
appearance.
[0108]
5 The rubber composition according to the second
embodiment of the present invention includes the ethylene-aolefin-
nonconjugated polyene random copolymer (I-l), and 50
percent by mass or more, preferably 60 percent by mass or
more, and particularly preferably 70 percent by mass or more
10 of the copolymer (I-l) is a specific ethylene-aolefin-
nonconjugated polyene random copolymer (Y) described
below. Use of the copolymer (Y) within the range exerts an
effect in obtaining a cross-linked foam exhibiting excellent
lightweightness.
15 [0109]
The rubber composition according to the third embodiment
of the present invention includes the ethylene-aolefin-
nonconjugated polyene random copolymer (I-l), and 10
to 50 percent by mass of the copolymer (I-l) is a specific
20 ethylene-a-olefin*nonconjugated polyene random copolymer (X)
described below and 90 to 50 percent by mass is a specific
ethylene'tt-olefin-nonconjugated polyene random copolymer (Y)
described below. Preferably, 10 to 40 percent by mass of the
copolymer (I-l) is the copolymer (X), and 90 to 60 percent by
SF-2464 45
mass is the copolymer (Y). Here, the total of the copolymer
(X) and the copolymer (Y) is preferably 100 percent by mass.
[0110]
Use of the copolymer (X) and the copolymer (Y) within
5 the range in combination can ensure the kneading workability
(handleability) and the fluidity of the rubber composition
suitable for molding and the mechanical strength of the
resulting cross-linked foam, and the use exerts an effect in
obtaining a cross-linked foam, which has small compression
10 set and surface roughness of the end portion surface and
which exhibits excellent lightweightness.
[0111]
Copolymers (X) and (Y)
The copolymer (X) is a copolymer containing structural
15 units [A] derived from ethylene, structural units [B] derived
from an a-olefin having the carbon number of 3 to 20,
structural units [C-1] derived from a nonconjugated polyene,
in which among carbon*carbon double bonds, only one
carbon-carbon double bond polymerizable with a metallocene
20 catalyst is present in one molecule, and structural units [C-
2] derived from a nonconjugated polyene, in which among the
carbon-carbon double bonds, two carbon-carbon double bonds
polymerizable with a metallocene catalyst are present in one
molecule, and satisfying the following requirements (1) to
SF-2464 46
(3) .
(1) The content of the structural units [B] derived from
an a-olefin having the carbon number of 3 to 20 is 10 to 50
5 percent by mole in 100 percent by mole of the total
structural units of the copolymer (X).
[0113]
(2) The total content of the structural units [C-1]
derived from a nonconjugated polyene, in which among
10 carbon-carbon double bonds, only one carbon-carbon double
bond polymerizable with a metallocene catalyst is present in
one molecule, and the structural units [C-2] derived from a
nonconjugated polyene, in which among the carbon-carbon
double bonds, two carbon-carbon double bonds polymerizable
15 with a metallocene catalyst are present in one molecule, is
1.0 to 6.0 percent by mole in 100 percent by mole of the
total structural units of the copolymer (X).
[0114]
(3) The limiting viscosity [r\] measured in a decalin
20 solution at 135°C is 2.0 to 4.0 dL/g.
[0115]
The copolymer (Y) is a copolymer containing structural
units [A'] derived from ethylene, structural units [B']
derived from an a-olefin having the carbon number of 3 to 20,
SF-2464 47
structural units [C-1'] derived from a nonconjugated polyene,
in which among carbon-carbon double bonds, only one
carbon-carbon double bond polymerizable with a metallocene
catalyst is present in one molecule, and structural units [C-
5 2'] derived from a nonconjugated polyene, in which among the
carbon-carbon double bonds, two carbon-carbon double bonds
polymerizable with a metallocene catalyst are present in one
molecule, and satisfying the following requirements (4) to
(6) .
10 [0116]
(4) The content of the structural units [B'] derived
from an a-olefin having the carbon number of 3 to 20 is 10 to
50 percent by mole in 100 percent by mole of the total
structural units of the copolymer (Y).
15 [0117]
(5) The total content of the structural units [C-1']
derived from a nonconjugated polyene, in which among
carbon-carbon double bonds, only one carbon-carbon double
bond polymerizable with a metallocene catalyst is present in
20 one molecule, and the structural units [C-2'] derived from a
nonconjugated polyene, in which among the carbon-carbon
double bonds, two carbon-carbon double bonds polymerizable
with a metallocene catalyst are present in one molecule, is
1.0 to 6.0 percent by mole in 100 percent by mole of the
SF-2464 48
t o t a l s t r u c t u r a l units of the copolymer (Y).
•
[0118]
(6) The limiting viscosity [r\] measured in a decalin
solution at 135°C is 0.8 to 1.8 dL/g.
5 [0119]
In the present specification, ethylene may be referred
to as Component [A], the a-olefin having the carbon number of
3 to 20 may be referred to as Component [B], the
nonconjugated polyene, in which among carbon*carbon double
10 bonds, only one carbon-carbon double bond polymerizable with
a metallocene catalyst is present in one molecule, may be
referred to as Component [C-1], and the nonconjugated polyene,
in which among the carbon-carbon double bonds, two
carbon-carbon double bonds polymerizable with the metallocene
15 catalyst are present in one molecule, may be referred to as
Component [C-2].
[0120]

The copolymer (X) contains structural units [A] derived
20 from ethylene.
[0121]
The copolymer (Y) contains structural units [A'] derived
from ethylene.
[0122]
SF-2464 49
The content of the structural units [A] in the copolymer
t {X) and the content of the structural units [A'] in the
copolymer (Y) are independently usually 44 to 88 percent by
mole, and preferably 50 to 73 percent by mole in 100 percent
5 by mole of the total structural units. It is preferable that
the contents of the structural units [A] and [A'] be within
the range because a cross-linked foam obtained from the
rubber composition including the copolymer (X) and/or the
copolymer (Y) has excellent flexibility and mechanical
10 characteristics at low temperatures. The content can be
determined on the basis of •'•^C-NMR.
[0123]

15 The copolymer (X) contains structural units [B] derived
from an a-olefin having the carbon number of 3 to 20. The
copolymer (Y) contains structural units [B'] derived from an
a-olefin having the carbon number of 3 to 20.
[0124]
20 The copolymer (X) and the copolymer (Y) independently
contain structural units derived from at least one type of aolefin
having the carbon number of 3 to 20, and may contain
structural units derived from at least two types of a-olefins
having the carbon number of 3 to 20.
SF-2464 50
[0125]
t The content of the structural units [B] in the copolymer
(X) and the content of the structural units [B'] in the
copolymer (Y) are independently 10 to 50 percent by mole, and
5 preferably 25 to 45 percent by mole in 100 percent by mole of
the total structural units. It is preferable that the
contents of the structural units [B] and [B'] be within the
range because a cross-linked foam obtained from the rubber
composition including the copolymer (X) and/or the copolymer
10 (Y) has excellent flexibility and mechanical characteristics
at low temperatures. The content can be determined on the
basis of ^^C-NMR.
[0126]
Examples of a-olefins having the carbon number of 3 to
15 20 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, aolefins
having the carbon number of 3 to 8, e.g., propylene,
1-butene, 1-hexene, and 1-octene, are preferable and
20 propylene is particularly preferable because the raw material
costs are relatively low and the resulting copolymer (X) and
copolymer (Y) exhibit excellent mechanical properties.
[0127]

^ The copolymer (X) contains structural units [C-1] and
structural units [C-2].
[0128]
5 The copolymer (Y) contains structural units [C-1'] and
structural units [C-2'].
[0129]
The copolymer (X) and the copolymer (Y) independently
contain structural units derived from at least one type of
10 Component [C-1], may contain structural units derived from at
least two types of Components [C-1], contain structural units
derived from at least one type of Component [C-2], and may
contain structural units derived from at least two types of
Component [C-2].
15 [0130]
In this regard, the structural units [C-1] and [C-1']
refer to a structural unit in which, in Component [C-1]
concerned, a carbon-carbon double bond polymerizable with a
metallocene catalyst is reacted and which is bonded to the
20 same type or another type of structural unit in that portion.
[0131]
Meanwhile, the structural units [C-2] and [C-2'] include
both a structural unit in which, in Component [C-2] concerned,
one carbon-carbon double bond polymerizable with a
SF-2464 52
#
metallocene catalyst is reacted and which is bonded to the
same type or another type of structural unit in that portion
and the other carbon-carbon double bond polymerizable with a
metallocene catalyst is not reacted and remains (the formula
5 (1) described below), and a structural unit in which one
carbon-carbon double bond polymerizable with a metallocene
catalyst is reacted and which is bonded to the same type or
another type of structural unit in that portion and the other
carbon-carbon double bond polymerizable with a metallocene
10 catalyst is reacted to form a branch structure (the formula
(2) described below). The following formulae (1) and (2)
show the case of 5-vinyl-2-norbornene.
[0132]
15
(1) (2)
«Component [C-1 ] »
Examples of Component [C-1] (nonconjugated polyene, in
SF-2464 53
which among carbon-carbon double bonds, only one
# carbon-carbon double bond polymerizable with a metallocene
catalyst is present in one molecule, preferably nonconjugated
diene) include aliphatic polyenes and alicyclic polyenes.
5 [0133]
Examples of the aliphatic polyenes do not include chain
polyenes, in which both terminals are vinyl groups (CH2=CH-),
but include compounds, in which one of the carbon-carbon
double bonds is present as a vinyl group at a molecular
10 terminal and the other carbon-carbon double bond(s) is/are
present as internal olefin bond(s) in a molecular chain (main
chain or side chain). The internal olefin bond is not
polymerized with a metallocene catalyst or the
polymerizability is poorer than that of the vinyl group.
15 [0134]
Specific examples of the aliphatic polyenes include 1,4-
hexadiene, 1,5-heptadiene, 1,6-octadiene, 1,7-nonadiene, 1,8-
decadiene, 1,12-tetradecadiene, 3-methyl-l,4-hexadiene, 4-
methyl-1,4-hexadiene, 5-methyl-l,4-hexadiene, 4-ethyl-l,4-
20 hexadiene, 3,3-dimethyl-l,4-hexadiene, 5-methyl-l,4-
heptadiene, 5-ethyl-l,4-heptadiene, 5-methyl-l,5-heptadiene,
6-methyl-l,5-heptadiene, 5-ethyl-l,5-heptadiene, 4-methyl-
1,4-octadiene, 5-methyl-l,4-octadiene, 4-ethyl-l,4-octadiene,
5-ethyl-l,4-octadiene, 5-methyl-l,5-octadiene, 6-methyl-l,5-
SF-2464 54
octadiene, 5-ethyl-l,5-octadiene, 6-ethyl-l,5-octadiene, 6-
^ methyl-1,6-octadiene, 7-methyl-l,6-octadiene, 6-ethyl-l,6- P
octadiene, 6-propyl-l,6-octadiene, 6-butyl-l,6-octadiene, 4-
methyl-1,4-nonadiene, 5-methyl-l,4-nonadiene, 4-ethyl-l,4-
5 nonadiene, 5-ethyl-l,4-nonadiene, 5-methyl-l,5-nonadiene, 6-
methyl-1,5-nonadiene, 5-ethyl-l,5-nonadiene, 6-ethyl-l,5-
nonadiene, 6-methyl-l,6-nonadiene, 7-methyl-l,6-nonadiene, 6-
ethyl-1,6-nonadiene, 7-ethyl-l,6-nonadiene, 7-methyl-l,7-
nonadiene, 8-methyl-l,7-nonadiene, 7-ethyl-l,7-nonadiene, 5-
10 methyl-1,4-decadiene, 5-ethyl-l,4-decadiene, 5-methyl-l,5-
decadiene, 6-methyl-l,5-decadiene, 5-ethyl-l,5-decadiene, 6-
ethyl-1,5-decadiene, 6-methyl-l,6-decadiene, 6-ethyl-l,6-
decadiene, 7-methyl-l,6-decadiene, 7-ethyl-l,6-decadiene, 7-
methyl-1,7-decadiene, 8-methyl-l,7-decadiene, 7-ethyl-l,7-
15 decadiene, 8-ethyl-l,7-decadiene, 8-methyl-l,8-decadiene, 9-
methyl-1,8-decadiene, 8-ethyl-l,8-decadiene, 6-methyl-l,6-
undecadiene, 9-methyl-l,8-undecadiene, and 4,8-dimethyl-
1,4,8-decatriene. Among them, 7-methyl-l,6-octadiene is
preferable.
20 [0135]
One type of aliphatic polyene can be used alone or at
least two types can be used in combination.
[0136]
Examples of alicyclic polyenes include compounds
SF-2464 55
composed of an alicyclic portion having one carbon-carbon
j^ double bond polymerizable with a metallocene catalyst and a m
chain portion having an internal olefin bond (carbon-carbon
double bond), e.g., an alkylidene group, which is not
5 polymerized with a metallocene catalyst or the
polymerizability of which is poor. 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
10 polyenes include 2-methyl-2,5-norbornadiene and 2-ethyl-2,5-
norbornadiene.
[0137]
One type of alicyclic polyene can be used alone or at
least two types can be used in combination.
15 [0138]
«Component [C-2]»
Examples of Component [C-2] (nonconjugated polyene, in
which among carbon-carbon double bonds, two carbon-carbon
double bonds polymerizable with a metallocene catalyst are
20 present in one molecule, preferably nonconjugated diene)
include 5-alkenyl-2-norbornene, e.g., 5-vinyl-2-norbornene
(VNB) and 5-allyl-2-norbornene; alicyclic polyenes, e.g.,
2,5-norbornadiene, dicyclopentadiene (DCPD), and
tetracyclo [4, 4, 0,1^-^, l'''^°]deca-3, 8-diene; and a,co-dienes.
SF-2464 56
e.g., 1,7-octadiene and 1,9-decadiene. Among them, 5-vinyl-
^^ 2-norbornene (VNB), dicyclopentadiene (DCPD), 2,5-
norbornadiene, 1,7-octadiene, and 1,9-decadiene are
preferable, and 5-vinyl-2-norbornene (VNB) is particularly
5 preferable.
[0139]
One type of them can be used alone or at least two types
can be used in combination.
[0140]
10 «Contents of structural units [C-1] and [C-2] and
contents of structural units [C-1'] and [C-2']»
The total content of the structural units [C-1] and the
structural units [C-2] in the copolymer (X) and the total
content of the structural units [C-1'] and the structural
15 units [C-2'] in the copolymer (Y) are independently 1.0 to
6.0 percent by mole, and preferably 1.0 to 5.0 percent by
mole in 100 percent by mole of the total structural units.
It is preferable that the total contents of these structural
units be within the range because the network structure can
20 be controlled relatively easily and, thereby, a good balance
can be ensured between the cross-linking rate and the
evaporation rate of water. The total content can be
determined on the basis of ^^C-NMR.
[0141]
SF-2464 57
It is preferable that the copolymer (X) and/or the
^^ copolymer (Y) contain structural units derived from 5-
ethylidene-2-norbornene (ENB). In 100 percent by mole of the
total structural units of the copolymer (X) or in 100 percent
5 by mole of the total structural units of the copolymer (Y),
the contents of the structural units derived from 5-
ethylidene-2-norbornene (ENB) are independently preferably 1
to 5 percent by mole, and more preferably 1 to 4 percent by
mole. It is preferable that the content of the structural
10 units be within the range because the cross-linking
reactivity can be controlled relatively easily and, in
addition, a cross-linked foam obtained from the rubber
composition including the copolymer (X) and/or the copolymer
(Y) has excellent rubber elasticity. The content can be
15 determined on the basis of •'•^C-NMR.
[0142]
It is preferable that the copolymer (X) and/or the
copolymer (Y) contain structural units derived from 5-vinyl-
2-norbornene (VNB). In 100 percent by mass of the total
20 structural units of the copolymer (X) or in 100 percent by
mass of the total structural units of the copolymer (Y), the
contents of the structural units derived from 5-vinyl-2-
norbornene (VNB) are independently preferably 0.01 to 0.45
percent by mole, and more preferably 0.05 to 0.40 percent by
SF-2464 58
mole. It is preferable that the content of the structural
-1^^^ units be within the range because appropriate branch w
structures can be introduced into the copolymer (X) and the
copolymer (Y), outgassing can be suppressed and, thereby, the
5 surface smoothness of the resulting cross-linked foam becomes
good, or the specific gravity of the resulting cross-linked
foam is reduced. The above-described content can be
determined on the basis of •^•^C-NMR.
[0143]
10
The limiting viscosity [r|] of the copolymer (X) measured
in a decalin solution at 135°C is 2.0 to 4.0 dL/g, preferably
2.3 to 4.0 dL/g, and more preferably 2.5 to 4.0 dL/g. The
copolymer (X) is a component contributing to improvements in
15 the kneading workability (handleability) and the mechanical
strength of the cross-linked foam. It is preferable that the
[ri] be within the range because extrusion molding and foam
molding can be performed favorably, and in the case where the
resulting cross-linked foam is used as a weather strip sponge,
20 a good sealing property is obtained.
[0144]
The limiting viscosity [r]] of the copolymer (Y) measured
in a decalin solution at 135°C is 0.8 to 1.8 dL/g, preferably
1.0 to 1.8 dL/g, and more preferably 1.0 to 1.6 dL/g. The
SF-2464 59
copolymer (Y) is a component contributing to an improvement
^ in the fluidity of the rubber composition. It is preferable
that the [r\] be within the range because the rubber
composition exhibits excellent fluidity, in-mold foam molding
5 can be performed favorably, and in the case where the
resulting cross-linked foam is used as an automobile
cushioning material and heat insulating material, good
dynamic characteristics are obtained. In addition, it is
preferable that the [r\] be within the range because molding
10 can be performed favorably, and a rubber molded article
having a shape complicated along with enhancement of
performance and functionality of the individual parts can be
obtained.
[0145]
15
Preferable examples of the copolymers (X) and the
copolymers (Y) include ethylene-a-olefin*5-ethylidene-2-
norbornene (ENB)•5-vinyl-2-norbornene (VNB) quatercopolymer,
ethylene•a-olefin•5-butylidene-2-norbornene•5-vinyl-2-
20 norbornene (VNB) quatercopolymer, and ethylene-a-olefin-4,8-
dimethyl-1,4,8-decatriene•5-vinyl-2-norbornene (VNB)
quatercopolymer. Ethylene•a-olefin•5-ethylidene-2-norbornene
(ENB)•5-vinyl-2-norbornene (VNB) quatercopolymer is
particularly preferable.
SF-2464 60
[0146]
A copolymer produced from ethylene, propylene, 5-
ethylidene-2-norbornene (ENB), and 5-vinyl-2-norbornene (VNB)
will be taken as an example of the copolymer (X) and the
5 copolymer (Y), and a method for measuring the contents of the
individual structural units will be described.
[0147]
The structure (composition) analysis of the abovedescribed
copolymer through the use of •'••^C-NMR can be
10 performed on the basis of "Macromolecules, 1977, Vol. 10, p.
536-544" by C. J. Carman, R. A. Harrington, and C. E. Wilkes,
"Macromolecules, 1982, Vol. 15, p. 1150-1152" by Masahiro
Kakugo, Yukio Naito, Kooji Mizunuma, and Tatsuya Miyatake,
and "Macromolecules, 1983, Vol. 16, p. 85-89" by G. Van der
15 Velden. The structure analysis of the VNB copolymer can be
performed on the basis of "Macromol. Rapid Commun., 1999, Vol
20, p. 356-360" by Harri Lasarov and Tuula T. Pakkanen and
"Macromol. Rapid Commun., 2001, Vol. 22, p. 434-438" by Harri
Lasarov and Tuula T. Pakkanen.
20 [0148]
Initially, the integral values of the individual peaks
derived from ethylene, propylene, ENB, and VNB in the
copolymer (X) and the copolymer (Y) are determined through
the use of •^'^C-NMR on the basis of the following items 1) to
SF-2464 61
^^^^
4) .
[0149]
1) ethylene: [integral of peak derived from ethylene
sequence] + [integral of peak derived from ethylene-propylene
5 sequence]/2
2) propylene: [integral of peak derived from propylene
sequence] + [integral of peak derived from ethylene-propylene
sequence]/2
3) ENB: integral of peak of ENB-position 3
10 4) VNB: integral of peak of VNB-position 7
Chemical formulae of structural units (E-isomer, Zisomer)
derived from ENB and chemical formulae of structural
units (endo (n), exo (x)) derived from VNB in the copolymer
(X) and the copolymer (Y) are described below.
15 [0150]
E isomer • Z isomer
[0151]
SF-2464 62
!^^
e n d o (n) e X o (x)
The percent by mole of the structural units derived from
ethylene, propylene, ENB, and VNB are calculated from the
ratio of the resulting integrals. In this regard, conversion
5 to percent by mole is performed on the assumption that the
molecular weight of ethylene is 28.05, the molecular weight
of propylene is 42.08, and the molecular weights of ENB and
VNB are 120.2.
[0152]
10
Component [A], Component [B], Component [C-1], and
Component [C-2] described above are used as monomers, and the
copolymer (X) and the copolymer (Y) are copolymers containing
15 structural units derived from these raw materials.
[0153]
The copolymer (X) and the copolymer (Y) are polymers
different from each other mainly in the limiting viscosity
[r\] . These limiting viscosities [r|] can be adjusted by, for
SF-2464 63
example, the amount of supply of hydrogen in polymerization.
It is preferable that the copolymer (X) and the
copolymer (Y) are copolymers produced by using a metallocene
5 catalyst represented by Formula (I), Formula (II), or Formula
(III) because the composition in the copolymer can be
controlled relatively easily.
[0155]
In this regard, in the following explanations of each
10 formula, examples of hydrocarbyl having the carbon number of
1 to 20 include linear alkyls, e.g., methyl, ethyl, and
butyl; and branched alkyls, e.g., t-butyl and neopentyl.
Examples of hydrocarbyloxy having the carbon number of 1 to
20 include linear alkyloxy, e.g., methyloxy, ethyloxy, and
15 butyloxy, and branched alkyloxy, e.g., t-butyloxy and
neopentyloxy. Examples of halogenated alkyl having the
carbon number of 1 to 20 include groups produced by
chlorinating, brominating, or fluorinating the linear alkyl
or branched alkyl. Examples of halogenated aryl include
20 chlorophenyl and chloronaphthyl.
[0156]
SF-2464 64
(I)
In Formula (I), each R represents independently a group
selected from hydrocarbyl, halohydrocarbyl, silyl, germyl,
and combinations thereof or a hydrogen atom, and the number
5 of atoms excluding hydrogen, included in the group, is 20 or
less.
[0157]
The letter M represents titanium, zirconium, or hafnium.
[0158]
10 The letter Y represents -0-, -S-, -NR*-, or -PR*-,
[0159]
The letter R* represents a hydrogen atom, hydrocarbyl,
hydrocarbyloxy, silyl, halogenated alkyl, or halogenated aryl,
and in the case where R* is not hydrogen, R* includes 20 or
15 less of atoms excluding hydrogen.
[0160]
The letter Z represents a divalent group including boron
or a group 14 element and, in addition, including nitrogen,
phosphorus, sulfur or oxygen, and the number of atoms
SF-2464 65
excluding hydrogen, included in the divalent group, is 60 or
less.
[0161]
The letter X represents, or in the case where a
5 plurality of X is present, each X represents independently,
an anionic ligand having the number of atoms of 60 or less
(where a cyclic ligand, in which n electrons are delocalized,
is excluded.). The letter X' represents, or in the case
where a plurality of X' is present, each X' represents
10 independently, a neutral linked compound having the number of
atoms of 20 or less.
[0162]
The letter p represents 0, 1, or 2.
[0163]
15 The letter q represents 0 or 1.
[0164]
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,
20 di(hydrocarbyl)amide, di(hydrocarbyl)phosphide, hydrocarbyl
sulfide, silyl, halo-substituted derivatives thereof,
di(hydrocarbyl)amino-substituted derivatives thereof,
hydrocarbyloxy-substituted derivatives thereof, and
di(hydrocarbyl)phosphino-substituted derivatives thereof, and
SF-2464 66
the number of atoms excluding hydrogen of X is 20 or less.
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
5 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 a metallacyclopentene
ring with M.
10 [0166]
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 nonconjugated
diene, which may be substituted with at least one hydrocarbyl,
which has the number of carbon atoms of 40 or less, and which
15 forms a n complex with M.
[0167]
(II)
In Formula (II), R^ and R^ represent independently a
hydrogen atom or an alkyl having the carbon number of 1 to 6,
SF-2464 67
and at least one of R^ and R^ is not a hydrogen atom. The
Letters R"^ to R^ represent independently a hydrogen atom or an
alkyl having the carbon number of 1 to 6. In this regard, R
to R^ may be bonded to each other to form a ring.
5 [0168]
The letter M represents titanium.
[0169]
The letter Y represents -0-, -S-, -NR*-, or -PR*-.
[0170]
10 The letter Z* represents -SiR*2-, -CR*2-A -SiR*2SiR*2-/ "
CR*2CR*2-/ -CR*=CR*-, -CR*2SiR*2-/ or -GeR*2--
[0171]
Each letter R* represents independently a hydrogen atom,
hydrocarbyl, hydrocarbyloxy, silyl, halogenated alkyl, or
15 halogenated aryl, 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) included in Z* may be
bonded to each other to form a ring, or R* in Z* and R* in Y
may be bonded to each other to form a ring.
20 [0172]
The letter p represents 0, 1, or 2.
[0173]
The letter q represents 0 or 1.
[0174]
SF-2464 68
In the case where p is 2; q is 0, M is in an oxidized
state of +4, and each X represents independently methyl or
benzyl. In the case where p is 1; q is 0, M is in an
oxidized state of +3, and X is 2-(N,N'-dimethyl)aminobenzyl
5 or M is in an oxidized state of +4, and X is 1,3-butadienyl.
In the case where p is 0; q is 1, M is in an oxidized state
of +2, and X is 1,4-diphenyl-l,3-butadiene, 2,4-hexadiene or
1,3-pentadiene.
[0175]
10
MXpX'qX'V
( I I I )
In Formula (III), R' represents a hydrogen atom,
hydrocarbyl, di(hydrocarbyl)amino, or hydrocarbyleneamino,
and R' other than a hydrogen atom has the carbon number of 1
to 20.
15 [0176]
The letter R" represents a hydrogen atom or hydrocarbyl
having the carbon number of 1 to 20.
[0177]
The letter M represents titanium.
SF-2464 69
[0178]
The letter Y represents -0-, -S-, -NR*-, -PR*-, -NR2*,
or -PR2*.
[0179]
5 The letter Z* represents -SiR*2-f -CR*2-f -SiR*2SiR*2-f "
CR*2CR*2-/ -CR*=CR*-, -CR*2SiR*2-f or -GeR*2-.
[0180]
Each R* represents independently a hydrogen atom,
hydrocarbyl, hydrocarbyloxy, silyl, halogenated alkyl, or
10 halogenated aryl, R* other than a hydrogen atom 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) included in Z* may be
bonded to each other to form a ring, or R* in Z* and R* in Y
may be bonded to each other to form a ring.
15 [0181]
The letter X represents a monovalent anionic ligand
having the number of atoms of 60 or less excluding cyclic
ligands, in which n electrons are delocalized. The letter X'
represents a neutral linked group having the number of atoms
20 of 20 or less. The letter 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.
[0182]
SF-2464 70
In the case where p is 2; q and r are 0, M is in an
oxidized state of +4 (where the case, in which Y is -NR*2 o^
-PR*2f is excluded) or M is in an oxidized state of +3 (where
y is -NR*2 or -PR*2)/ arid X is an anionic ligand selected
5 from the group consisting of a halide group, a hydrocarbyl
group, a hydrocarbyloxy group, a di(hydrocarbyl)amide group,
a di(hydrocarbyl)phosphide group, a hydrocarbyl sulfide group
and a silyl group, halogen-substituted groups of these groups,
di(hydrocarbyl)amino-substituted groups of these groups,
10 hydrocarbyloxy-substituted groups of these groups, and
di(hydrocarbyl)phosphino-substituted groups of these groups
while the groups include atoms of the atomic number of 2 to
30.
[0183]
15 In the case where r is 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"
includes atoms of the atomic number of 2 to 30. In the case
20 where p is 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 group, 2-(N,N-dimethylamino)phenyl
group, 2-(N,N-dimethylaminomethyl)phenyl group, and 2-(N,Ndimethylamino)
benzyl group. In the case where p and r are 0;
SF-2464 71
q is 1, M is in an oxidized state of +2, X' is a neutral
^ conjugated diene or a neutral nonconjugated diene optionally
substituted with at least one hydrocarbyl group, and X' has
the number of carbon atoms of 40 or less and forms a bond
5 with M through n-n interaction.
[0184]
As for more preferable embodiments, in the case where p
is 2 and q and r are 0 in Formula (III); M is in an oxidized
state of +4, and each of X is independently methyl, benzyl,
10 or halide. In the case where p and q are 0; r is 1, M is in
an oxidized state of +4, and X" is 1,3-butadienyl, which
forms a metallacyclopentene ring with M. In the case where p
is 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
15 are 0; q is 1, M is in an oxidized state of +2, and X' is
1,4-diphenyl-l,3-butadiene or 1,3-pentadiene.

SF-2464 150
CLAIMS
[Claim 1]
^1' A foaming agent formed from at least (A) a high
molecular compound having a saturated water absorption of 10
5 to 1,000 g/g in ion-exchanged water (25°C) and (B) water,
wherein a storage modulus (G') of the agent, determined on
the basis of a viscoelasticity measurement at a temperature
of 20°C, is 8.0 X 10^ to 1.0 x 10^ Pa at a frequency of 5
rad/s.
10 [Claim 2]
The foaming agent according to Claim 1, wherein the high
molecular compound (A) has a saturated water absorption of
250 to 1,000 g/g in ion-exchanged water (25°C).
[Claim 3]
15 The foaming agent according to Claim 1 or Claim 2, which
is a foaming agent for rubber foaming.
[Claim 4]
The foaming agent according to any one of Claims 1 to 3,
wherein the high molecular compound (A) is a carboxyl group-
20 containing high molecular compound exhibiting a hydrogelforming
property.
[Claim 5]
The foaming agent according to any one of Claims 1 to 4,
wherein the water content is 99.85 to 70 percent by mass.
SF-2464 151
[Claim 6]
A method for manufacturing the foaming agent according
to Claim 1, the method comprising the step of mixing (A) a
high molecular compound having a saturated water absorption
5 of 10 to 1,000 g/g in ion-exchanged water (25°C) and (B)
water.
[Claim 7]
A forming agent for the foaming agent according to Claim
1, comprising (A) a high molecular compound having a
10 saturated water absorption of 10 to 1,000 g/g in ionexchanged
water (25°C).
[Claim 8]
A rubber composition comprising:
100 parts by mass of (I) at least one type of rubber
15 component selected from natural rubber and synthetic rubber;
and
0.5 to 300 parts by mass of (II) the foaming agent
according to any one of Claims 1 to 5.
[Claim 9]
20 A rubber composition comprising 100 parts by mass of (I-
1) an ethylene•a-olefin-nonconjugated polyene random
copolymer and 0.5 to 300 parts by mass of (II) the foaming
agent according to any one of Claims 1 to 5,
wherein 50 percent by mass or more of the copolymer (ISF-
2464 152
1) is a copolymer (X) containing structural units [A] derived
from ethylene, structural units [B] derived from an a-olefin
^1* having the carbon number of 3 to 20, structural units [C-1]
derived from a nonconjugated polyene, in which among
5 carbon-carbon double bonds, only one carbon-carbon double
bond polymerizable with a metallocene catalyst is present in
one molecule, and structural units [C-2] derived from a
nonconjugated polyene, in which among the carbon-carbon
double bonds, two carbon-carbon double bonds polymerizable
10 with a metallocene catalyst are present in one molecule, and
satisfying the following requirements (1) to (3),
(1) the content of the structural units [B] is 10 to 50
percent by mole in 100 percent by mole of the total
structural units of the copolymer (X),
15 (2) the total content of the structural units [C-1] and
the structural units [C-2] is 1.0 to 6.0 percent by mole in
100 percent by mole of the total structural units of the
copolymer (X), and
(3) the limiting viscosity [r\] measured in a decalin
20 solution at 135°C is 2.0 to 4.0 dL/g.
[Claim 10]
The rubber composition according to Claim 9,
wherein in the copolymer (X),
at least part of the structural units [C-1] are
SF-2464 153
structural units derived from 5-ethylidene-2-norbornene (ENB)
and the content of structural units derived from ENB is 1 to
5 percent by mole in 100 percent by mole of the total
structural units of the copolymer (X), and
5 at least part of the structural units [C-2] are
structural units derived from 5-vinyl-2-norbornene (VNB) and
the content of structural units derived from VNB is 0.01 to
0.45 percent by mole in 100 percent by mole of the total
structural units of the copolymer (X).
10 [Claim 11]
The rubber composition according to Claim 9 or Claim 10,
which is a rubber composition for extrusion foam molding.
[Claim 12]
A rubber composition comprising 100 parts by mass of (I-
15 1) an ethylene-a-olefin-nonconjugated polyene random
copolymer and 0.5 to 300 parts by mass of (II) the foaming
agent according to any one of Claims 1 to 5,
wherein 50 percent by mass or more of the copolymer (I-
1) is a copolymer (Y) containig structural units [A'] derived
20 from ethylene, structural units [B'] derived from an a-olefin
having the carbon number of 3 to 20, structural units [C-1']
derived from a nonconjugated polyene, in which among
carbon-carbon double bonds, only one carbon-carbon double
bond polymerizable with a metallocene catalyst is present in
SF-2464 154
one molecule, and structural units [C-2'] derived from a
nonconjugated polyene, in which among the carbon-carbon
w double bonds, two carbon-carbon double bonds polymerizable
with a metallocene catalyst are present in one molecule, and
5 satisfying the following requirements (4) to (6),
(4) the content of the structural units [B'] is 10 to 50
percent by mole in 100 percent by mole of the total
structural units of the copolymer (Y),
(5) the total content of the structural units [C-1'] and
10 the structural units [C-2'] is 1.0 to 6.0 percent by mole in
100 percent by mole of the total structural units of the
copolymer (Y), and
(6) the limiting viscosity [T|] measured in a decalin
solution at 135°C is 0.8 to 1.8 dL/g.
15 [Claim 13]
The rubber composition according to Claim 12,
wherein in the copolymer (Y) ,
at least part of the structural units [C-1'] are
structural units derived from 5-ethylidene-2-norbornene (ENB)
20 and the content of structural units derived from ENB is 1 to
5 percent by mole in 100 percent by mole of the total
structural units of the copolymer (Y), and
at least part of the structural units [C-2'] are
structural units derived from 5-vinyl-2-norbornene (VNB) and
SF-2464 155
the content of structural units derived from VNB is 0.01 to
0.45 percent by mole in 100 percent by mole of the total
W structural units of the copolymer (Y).
[Claim 14]
5 The rubber composition according to Claim 12 or Claim 13,
which is a rubber composition for in-mold foam molding.
[Claim 15]
A rubber composition comprising 100 parts by mass of (I-
1) an ethylene-a-olefin-nonconjugated polyene random
10 copolymer and 0.5 to 300 parts by mass of (II) the foaming
agent according to any one of Claims 1 to 5,
wherein 10 to 50 percent by mass of the copolymer (I-l)
is a copolymer (X) containing structural units [A] derived
from ethylene, structural units [B] derived from an a-olefin
15 having the carbon number of 3 to 20, structural units [C-1]
derived from a nonconjugated polyene, in which among
carbon-carbon double bonds, only one carbon-carbon double
bond polymerizable with a metallocene catalyst is present in
one molecule, and structural units [C-2] derived from a
20 nonconjugated polyene, in which among the carbon-carbon
double bonds, two carbon-carbon double bonds polymerizable
with a metallocene catalyst are present in one molecule, and
satisfying the following requirements (1) to (3), and
Wherein 90 to 50 percent by mass of the copolymer (I-l)
SF-2464 156
is a copolymer (Y) containing structural units [A'] derived
from ethylene, structural units [B'j derived from an a-olefin
^ having the carbon number of 3 to 20, structural units [C-1']
derived from a nonconjugated polyene, in which among
5 carbon*carbon double bonds, only one carbon*carbon double
bond polymerizable with a metallocene catalyst is present in
one molecule, and structural units [C-2'] derived from a
nonconjugated polyene, in which among the carbon*carbon
double bonds, two carbon*carbon double bonds polymerizable
10 with a metallocene catalyst are present in one molecule, and
satisfying the following requirements (4) to (6),
(1) the content of the structural units [B] is 10 to 50
percent by mole in 100 percent by mole of the total
structural units of the copolymer (X),
15 (2) the total content of the structural units [C-1] and
the structural units [C-2] is 1.0 to 6.0 percent by mole in
100 percent by mole of the total structural units of the
copolymer (X),
(3) the limiting viscosity [r\] measured in a decalin
20 solution at 135°C is 2.0 to 4.0 dL/g,
(4) the content of the structural units [B'] is 10 to 50
percent by mole in 100 percent by mole of the total
structural units of the copolymer (Y),
(5) the total content of the structural units [C-1'] and
SF-2464 157
the structural units [C-2'] is 1.0 to 6.0 percent by mole in
100 percent by mole of the total structural units of the
^* copolymer (Y), and
(6) the limiting viscosity [r\] measured in a decalin
5 solution at 135°C is 0.8 to 1.8 dL/g.
[Claim 16]
The rubber composition according to Claim 15,
wherein in the copolymer (X),
at least part of the structural units [C-1] are
10 structural units derived from 5-ethylidene-2-norbornene (ENB)
and the content of structural units derived from ENB is 1 to
5 percent by mole in 100 percent by mole of the total
structural units of the copolymer (X), and
at least part of the structural units [C-2] are
15 structural units derived from 5-vinyl-2-norbornene (VNB) and
the content of structural units derived from VNB is 0.01 to
0.45 percent by mole in 100 percent by mole of the total
structural units of the copolymer (X), and
in the copolymer (Y),
20 at least part of the structural units [C-1'] are
structural units derived from 5-ethylidene-2-norbornene (ENB)
and the content of structural units derived from ENB is 1 to
5 percent by mole in 100 percent by mole of the total
structural units of the copolymer (Y), and
SF-2464 158
at least part of the structural units [C-2'] are
structural units derived from 5-vinyl-2-norbornene (VNB) and
^*''' the content of structural units derived from VNB is 0.01 to
0.45 percent by mole in 100 percent by mole of the total
5 structural units of the copolymer (Y).
[Claim 17]
The rubber composition according to Claim 15 or Claim 16,
which is a rubber composition for molding.
[Claim 18]
10 The rubber composition according to any one of Claims 8
to 17, further comprising a cross-linking agent.
[Claim 19]
A cross-linked foam produced by cross-linking foam
molding the rubber composition according to any one of Claims
15 8 to 18.
[Claim 20]
A rubber molded article comprising the cross-linked foam
according to Claim 19.
[Claim 21]
20 An automobile weather strip sponge, an automobile
cushioning material, or an automobile heat insulating
material comprising the cross-linked foam according to Claim
19.
[Claim 22]
SF-2464 159
A method for manufacturing a cross-linked foam,
comprising the steps of extruding the rubber composition
^p'according to any one of Claims 9 to 11 by an extrusion i
molding method and heating the resulting extrusion molded
5 material to induce cross-linking and foaming.
[Claim 23]
A method for manufacturing a cross-linked foam,
comprising a first foaming step to fill the rubber
composition according to any one of Claims 12 to 14 into a
10 primary mold, perform heating under pressure and,
subsequently, reduce the pressure to induce foaming and a ,
second foaming step to put the primary foamed material
obtained by the first foaming step into a secondary mold and
perform heating at normal pressure to induce foaming.
15 [Claim 24]
A method for manufacturing a cross-linked foam
comprising the steps of injecting the rubber composition
according to any one of Claims 15 to 17 into a mold by a
molding method and performing heating in the mold to induce
20 cross-linking and foaming.