The present invention relates to a thermoplastic elastomer
composition and a production process for the same. More particularly,
the present invention relates to a thermoplastic elastomer composition
10 capable of efficiently producing a molded product having excellent
mechanical properties such as rubber elasticity and excellent
appearance, and a production process for the composition.
Background Art
15 [0002)
A thermoplastic elastomer composition obtained by dynamically
heat-treating a rubber and a polyolefin-based resin in the presence
of a crosslinking agent generally has a structure wherein the rubber
component constitutes a soft segment (soft phase) which imparts
20 flexibility, the polyolefin-based resin constitutes a hard segment
(hard phase) which provides a pseudo crosslinked structure, and the
phase composed of the soft segment (referred to as an "island phase"
hereinafter) is dispersed in the phase composed of the hard segment
(referred to as a "sea phase" hereinafter) . Since the thermoplastic
SF-3059
2
elastomer composition has such a structure, it can exhibit excellent
mechanical properties such as rubber elasticity and tensile strength.
[0003]
The thermoplastic elastomer composition is produced mainly by
5 the use of a twin-screw extruder. However, when the twin-screw
extruder is used, dispersing of the island phase is not necessarily
sufficient, and therefore, a composition having excellent mechanical
properties and appearance has not been obtained in many cases. For
example, in patent literatures 1 to 4, a production process for a
10 thermoplastic elastomer composition using a twin-screw extruder is
disclosed. In the resulting thermoplastic elastomer composition,
however, dispersibility of the island phase is not necessarily
satisfactory, and development of a production process for a
thermoplastic elastomer composition in which further improvement in
15 dispersibility of the island phase is realized and which can produce
a molded product having more excellent mechanical properties and
appearance has been desired. A molded product is usually produced
by extrusion molding, and from the viewpoint of production efficiency,
higher extruder output is being desired.
20
Citation List
Patent Literature
[0004]
Patent literature 1: Japanese Patent Laid-Open Publication No.
SF-3059
3
2009-191138
Patent 1i terature 2: Japanese Patent Laid-Open Publication No.
2009-173927
Patent literature 3: Japanese Patent Laid-Open Publication No.
5 2003-147133
Patent literature 4: Japanese Patent Laid-Open Publication No.
2002-201313
Summary of Invention
10 Technical Problem
[0005)
It is an object of the present invention to provide a
thermoplastic elastomer composition capable of efficiently producing
a molded product having excellent mechanical properties such as rubber
15 elasticity and excellent appearance, and a production process for
a thermoplastic elastomer composition, by which such a thermoplastic
elastomer composition as above can be obtained.
Solution to Problem
20 [0006)
The present inventor has found that the above problem can be
solved by kneading the components under the specific conditions using
a batch mixer, and has completed the thermoplastic elastomer
composition of the present invention and a production process for
5
10
SF-3059
4
the composition.
[0007]
That is to say, the thermoplastic elastomer composition of the
present invention is obtained by dynamically crosslinking
an ethylene/a-olefin/non-conjugated polyene copolymer (A),
a polyolefin resin (B),
a softener (C) in an amount of 1 to 200 parts by mass per 100
parts by mass of the total of the copolymer (A) and the resin (B),
and
a crosslinking agent (D),
by the use of a batch mixer under the conditions satisfying
the following requirements (1) to (4):
(1) 50~P1~300
wherein P1 is defined by the following formula (i):
15 [0008]
20
[Math. 1]
P1 = yave.xLog(t1) (i)
wherein the residence time (sec) after the introduction of the
crosslinking agent (D) is denoted as t1 sec, and the average rate
(sec-1
) of shear rates y in the t1 is denoted as yave.
(2) 900~P2~1450
wherein P2 is defined by the following formula (ii):
[0009]
[Math. 2]
SF-3059
5
P2 = (Tave.+273)xLog(t1) (ii)
wherein the average resin temperature ('C) after the introduction
of the crosslinking agent (D) is denoted as Tave. ·c, and the residence
time (sec) after the introduction of the crosslinking agent (D) is
5 denoted as t1 sec,
10
( 3) -2. 5~P3~1. 5
wherein P3 is defined by the following formula (iii):
[0010]
[Math. 3]
P3 = Log(t1/t2) (iii)
wherein the residence time (sec) after the introduction of the
cross linking agent (D) is denoted as t1 sec, and the time (sec) required
for the residual amount of the crosslinking agent (D) to become not
more than 1 ppm of the introduction amount thereof at the average
15 resin temperature Tave. after the introduction of the crosslinking
agent (D) is denoted as t2 sec, and
(4) the crosslinking agent (D) is introduced into the batch
mixer after the ethylene/a-olefin/non-conjugated polyene copolymer
(A), the polyolefin resin (B) and the softener (C) have been introduced.
20 [0011]
In the thermoplastic elastomer composition, it is preferable
that the ethylene/a-olefin/non-conjugated polyene copolymer (A) and
the polyolefin resin (B) are contained in a mass ratio ((A) I (B)) of
90/10 to 10/90.
SF-3059
6
[0012]
In thermoplastic elastomer composition, it is preferable that
the crosslinking agent (D) is an organic peroxide and the amount of
the crosslinking agent (D) compounded is 0.01 to 3.0 parts by mass
5 per 100 parts by mass of the total of the copolymer (A) and the resin
(B) •
[0013]
In the thermoplastic elastomer composition, it is preferable
that the batch mixer is an intermeshing mixer.
10 [0014]
15
20
The production process for a thermoplastic elastomer
composition according to the present invention comprises dynamically
cross linking
an ethylene/a-olefin/non-conjugated polyene copolymer (A),
a polyolefin resin (B),
a softener (C) in an amount of 1 to 200 parts by mass per 100
parts by mass of the total of the copolymer (A) and the resin (B),
and
a crosslinking agent (D),
by the use of a batch mixer under the conditions satisfying
the following requirements (1) to (4):
(1) 50~Pl~300
wherein Pl is defined by the following formula (i):
[0015]
SF-3059
7
[Math. 1]
P1 = yave.xLog(t1) ( i)
wherein the residence time (sec) after the introduction of the
crosslinking agent (D) is denoted as t1 sec, and the average rate
5 (sec-1
) of shear rates y in the t1 is denoted as yave. sec-1
,
10
15
(2) 900~P2~1450
wherein P2 is defined by the following formula (ii):
[0016)
[Math. 2)
P2 = (Tave.+273)xLog(t1) (ii)
wherein the average resin temperature ('C) after the introduction
of the crosslinking agent (D) is denoted as Tave. 'C, and the residence
time (sec) after the introduction of the crosslinking agent (D) is
denoted as t1 sec,
(3) -2. %P3~1. 5
wherein P3 is defined by the following formula (iii):
[0017)
[Math. 3]
P3 = Log(t1/t2) (iii)
20 wherein the residence time (sec) after the introduction of the
crosslinking agent (D) is denoted as t1 sec, and the time (sec) required
for the residual amount of the crosslinking agent (D) to become not
more than 1 ppm of the introduction amount thereof at the average
resin temperature Tave. after the introduction of the crosslinking
SF-3059
8
agent (D) is denoted as t2 sec, and
(4) the crosslinking agent (D) is introduced into the batch
mixer after the ethylene/ex-olefin/non-conjugated polyene copolymer
(A), the polyolefin resin (B) and the softener (C) have been introduced.
5 [0018]
In the production process for a thermoplastic elastomer
composition, it is preferable that the
ethylene/ex-olefin/non-conjugated polyene copolymer (A) and the
polyolefin resin (B) are contained in a mass ratio ((A) I (B)) of 90/10
10 to 10/90.
[0019]
In the production process for a thermoplastic elastomer
composition, it is preferable that the crosslinking agent (D) is an
organic peroxide and the amount of the crosslinking agent (D)
15 compounded is 0. 01 to 3. 0 parts by mass per 100 parts by mass of the
total of the copolymer (A) and the resin (B) .
[0020]
In the production process for a thermoplastic elastomer
composition, it is preferable that the batch mixer is an intermeshing
20 mixer.
Advantageous Effects of Invention
[0021]
According to the thermoplastic elastomer composition of the
SF-3059
9
present invention, a molded product having excellent mechanical
properties such as rubber elasticity and excellent appearance can
be produced, and moreover, melt density and extruder output can be
enhanced, so that improvement in productivity can be accomplished.
5 The production process for a thermoplastic elastomer composition
according to the present invention can efficiently produce the
above-mentioned thermoplastic elastomer composition.
Description of Embodiments
10 [0022]
15
20

The thermoplastic elastomer composition of the present
invention is obtained by dynamically crosslinking
an ethylene/a-olefin/non-conjugated polyene copolymer (A),
a polyolefin resin (B),
a softener (C) in an amount of 1 to 200 parts by mass per 100
parts by mass of the total of the copolymer (A) and the resin (B),
and
a crosslinking agent (D),
by the use of a batch mixer under the conditions satisfying
the following requirements (1) to (4).
[0023]
The batch mixer is not specifically restricted, and it may be
a mixer of any form as far as it is a batch type. Of such mixers,
SF-3059
10
a batch mixer having intermeshing rotors is preferable.
[0024)
The intermeshing rotors are rotors having a structure wherein
biaxial rotors intermesh with each other and carry out kneading not
5 only between a rotor and a chamber wall surface but also between a
rotor and a rotor, and they have characteristics that the rotor
clearance is small and strong shearing is possible. The mixer having
intermeshing rotors is generally called an intermeshing mixer.
10
[ 002 5)
When a batch mixer having intermeshing rotors is used, it becomes
possible to sufficiently carry out dispersing of an island phase while
controlling kneading and dynamic crosslinking, and moreover,
formation of a gel-like substance is inhibited, whereby production
of a thermoplastic elastomer composition having better appearance
15 and having more excellent mechanical properties is realized.
[0026)
The batch mixer having intermeshing rotors is preferably an
internal kneading device.
Such a batch internal kneading device having intermeshing rotors
20 is, for example, an intermeshing mixer manufactured by
Harburg-Freudenberger Maschinenbau GmbH.
[0027)
The requirements (1) to (4) will be described hereinafter.
[0028)
SF-3059
11
Requirement (1) 50~P1~300
Here, P1 is defined by the following formula (i) .
[ 002 9]
[Math. 4)
5 P1 = yave.xLog(t1) ( i)
In the formula (i), the residence time (sec) after the
introduction of the cross linking agent (D) is denoted as t1 sec. That
is to say, the time (sec) for which the above components are being
kneaded in a batch mixer, said time being measured from the time when
10 the crosslinking agent (D) has been introduced into the batch mixer,
is t1 sec.
[0030]
In the formula (i), the average rate (sec-1
) of shear rates
yin the t1 is denoted as yave. sec-1
• That is to say, the average
15 shear rate (sec-1
) in the time for which the above components are being
kneaded in a batch mixer, said time being measured from the time when
the crosslinking agent (D) has been introduced into the batch mixer,
l. s yave. sec -1 .
[0031]
20 The shear rate y is determined by the following formula (iv).
[0032]
[Math. 5]
y = rrxDxN/h (iv)
In the formula (iv), D denotes a mean outside diameter (mm)
SF-3059
12
of the rotor, N denotes a rotational speed (rps) of the rotor, and
h denotes a tip clearance (mm) .
[0033]
If Pl is smaller than 50, the dispersed state of the island
5 phase is bad because of insufficient kneading, and the appearance
of a molded product is deteriorated. If Pl is larger than 300, lowering
of mechanical properties and deterioration of hue of the thermoplastic
elastomer composition take place because of deterioration of the resin.
10
15
20
[0034]
In the thermoplastic elastomer composition of the present
invention, it is more preferable that a requirement of 60~P1~275 is
satisfied, and it is still more preferable that a requirement of
70~P1~250 is satisfied.
[0035]
Requirement (2) 900~P2~1450
Here, P2 is defined by the following formula (ii) .
[0036]
[Math. 6]
P2 = (Tave.+273)xLog(tl) (ii)
In the formula (ii), tl has the same meaning as that of tl in
the formula (i).
[0037]
In the formula (ii), the average resin temperature ( oC) after
the introduction of the crosslinking agent (D) is denoted as Tave.
SF-3059
13
·C. That is to say, the average value of the resin temperatures (·C)
in the t1 is Tave. ·c.
[0038]
If P2 is smaller than 900, the dispersed state of the island
5 phase is bad because of insufficient kneading, and the appearance
of a molded product is deteriorated. Moreover, the progress of the
crosslinking reaction becomes insufficient, and the rubber elasticity
of the thermoplastic elastomer composition is deteriorated. If P2
is larger than 1450, lowering of mechanical properties and
10 deterioration of hue of the thermoplastic elastomer composition take
place because of deterioration of the resin.
[0039]
In the thermoplastic elastomer composition of the present
invention, it is more preferable that a requirement of 950~P2~1400
15 is satisfied, and it is still more preferable that a requirement of
1000~P2~1300 is satisfied.
[ 004 0 l
Requirement (3) -2.5~P3~1.5
Here, P3 is defined by the following formula (iii).
20 [0041]
[Math. 7]
P3 = Log(t1/t2) (iii)
In the formula (iii), t1 has the same meaning as that of t1
in the formula (i) .
SF-3059
14
[0042]
In the formula (iii), the time (sec) required for the residual
amount of the crosslinking agent (D) to become not more than 1 ppm
of the introduction amount thereof at the average resin temperature
5 Tave. after the introduction of the cross linking agent (D) is denoted
as t2 sec. That is to say, when the introduction amount of the
crosslinking agent (D) is denoted as V0 and the residual amount of
the crosslinking agent (D) given when t2 has passed at the average
resin temperature Tave. is denoted as Vt2 , a relationship of
10 Vt2/V0=1/1000000 is established. When the crosslinking agent (D) is
an organic peroxide, t2 can be readily determined by calculation from
the half-life of the crosslinking agent (D) and the data of activation
energy.
15
20
[0043]
The residual amount of the crosslinking agent is determined
by the following formula (v) .
[0044]
[Math. 8]
Residual amount of crosslinking agent (%)
exp(-kdxt2/3600)xl00 (v)
In the formula (v), kd denotes a rate constant and is obtained
by the following formula (vi) .
[ 004 5]
[Math. 9]
SF-3059
15
kd = Aexp(-~E/RT) (vi)
In the formula (vi), A denotes a frequency factor (hr-1
). A
is a numerical value inherent in the cross linking agent. ~E denotes
an activation energy (J/mol). ~E is a numerical value inherent in
5 the crosslinking agent. R denotes a gas constant (8.314 J/mol·K),
and T denotes an absolute temperature (OK).
[0046]
If P3 is smaller than -2.5, the progress of the crosslinking
reaction becomes insufficient, and the rubber elasticity of the
10 thermoplastic elastomer composition is deteriorated. If P3 is larger
than 1. 5, lowering of mechanical properties and deterioration of hue
of the thermoplastic elastomer composition take place because of
deterioration of the resin.
15
20
[ 004 7]
In the thermoplastic elastomer composition of the present
invention, it is more preferable that a requirement of -2.2~P3~1.2
is satisfied, and it is still more preferable that a requirement of
-2.0~P3~1.0 is satisfied.
[0048]
Requirement ( 4) The cross linking agent (D) is introduced into
the batch mixer after the ethylene/a-olefin/non-conjugated polyene
copolymer (A), the polyolefin resin (B) and the softener (C) have
been introduced.
[ 004 9]
SF-3059
16
That is to say, prior to the introduction of the cross linking
agent (D), the softener (C) has been introduced, and the softener
(C) has been kneaded with the ethylene/a-olefin/non-conjugated
polyene copolymer (A) and the polyolefin resin (B) . Thereafter, the
5 crosslinking agent (D) is introduced, and dynamic crosslinking is
carried out.
[0050]
By satisfying the requirement (4), it becomes possible to
sufficiently disperse the island phase.
10 [0051]
Although the interval between the introduction of the
ethylene/a-olefin/non-conjugated polyene copolymer (A), the
polyolefin resin (B) and the softener (C) and the introduction of
the crosslinking agent (D) is not specifically restricted, it is
15 preferable to introduce the crosslinking agent (D) promptly after
the introduction of the softener (C). That is to say, it is preferable
that the crosslinking agent (C) is introduced while the temperature
of the kneadate in the batch mixer is low after the temperature thereof
is lowered by the introduction of softener (C) . Specifically,
20 kneading of the ethylene/a-olefin/non-conjugated polyene copolymer
(A) and the polyolefin resin (B) is carried out at about 175'C in
the batch mixer, and when the temperature of the kneadate is lowered
to not higher than 160'C, preferably not higher than 150'C, more
preferably not higher than 140'C, by the introduction of the softener
SF-3059
17
(C), the crosslinking agent (D) is introduced.
[0052]
The components contained in the thermoplastic elastomer
composition of the present invention will be described hereinafter.
5 [0053]
10
In the thermoplastic elastomer composition of the present
invention, the ethylene/a-olefin/non-conjugated polyene copolymer
(A) forms an island phase.
[0054]
Astheethylene/a-olefin/non-conjugatedpolyenecopolymer(A),
any of well-known various olefin-based copolymer rubbers can be used.
Here, the ethylene/a-olefin/non-conjugated polyene copolymer rubber
is preferably an amorphous random elastomeric copolymer composed of
ethylene, an a-olefin of 3 to 20 carbon atoms and a non-conjugated
15 polyene, and is preferably an olefin-based copolymer rubber which
is decreased in fluidity or loses fluidity when it is mixed with a
peroxide, kneaded under heating and thereby crosslinked.
[0055]
Such an olefin-based copolymer rubber is specifically, for
20 example, an ethylene/a-olefin/non-conjugated diene copolymer rubber
(ethylene/a-olefin (ratio by mol) : about 90/10 to 50/50).
[0056]
Specific examples of the non-conjugated dienes include
non-conjugated dienes, such as dicyclopentadiene, 1,4-hexadiene,
SF-3059
18
cyclooctadiene, methylene norbornene and ethylidene norbornene. Of
such copolymer rubbers, preferable are
ethylene/propylene/non-conjugated diene copolymer rubbers and
ethylene/1-butene/non-conjugated diene copolymer rubbers, and more
5 preferable are ethylene/propylene/non-conjugated diene copolymer
rubbers. Of these, an ethylene/propylene/ethylidene norbonene
copolymer rubber is particularly preferable.
[0057]
Specific examples of the non-conjugated polyenes other than
10 the non-conjugated dienes include non-conjugated trienes, such as
6,10-dimethyl-1,5,9-undecatriene, 5,9-dimethyl-1,4,8-decatriene,
6,9-dimethyl-1,4,8-decatriene, 6,8,9-trimethyl-1,5,8-decatriene,
6-ethyl-10-methyl-1,5,9-undecatriene,
4-ethylidene-1,6-octadiene,7-methyl-4-ethylidene-1,6-octadiene,
15 7-methyl-4-ethylidene-1,6-nonadiene,
7-ethyl-4-ethylidene-1,6-nonadiene,
6,7-dimethyl-4-ethylidene-1,6-octadiene,
6,7-dimethyl-4-ethylidene-1,6-nonadiene,
4-ethylidene-1,6-decadiene, 7-methyl-4-ethylidene-1,6-decadiene,
20 7-methyl-6-propyl-4-ethylidene-1,6-octadiene,
4-ethylidene-1,7-nonadiene, 8-methyl-4-ethylidene-1,7-nonadiene
and 4-ethylidene-1,7-undecadiene.
[0058]
The Mooney viscosity (ML1+4 (100"C)) of the
5
SF-3059
19
ethylene/a-olefin/non-conjugatedpolyenecopolymer (A) ispreferably
in the range of 10 to 250, particularly preferably in the range of
50 to 200.
[ 005 9]
The iodine value of the ethylene/a-olefin/non-conjugated
polyene copolymer (A) is preferably not more than 25. When the iodine
value of the ethylene/a-olefin/non-conjugated polyene copolymer (A)
is in such a range, a thermoplastic elastomer composition having been
partially crosslinked with a good balance is obtained.
10 [0060]
Theethylene/a-olefin/non-conjugatedpolyenecopolymer(A) and
a rubber other than the ethylene/a-olefin/non-conjugated polyene
copolymer (A) can be also used in combination. Examples of such rubbers
other than the ethylene/a-olefin/non-conjugated polyene copolymer
15 (A) include diene-based rubbers, such as styrene-butadiene rubber
(SBR), nitrile rubber (NBR) and natural rubber (NR), and silicon
rubber.
[0061]
The polyolefin resin (B) forms a sea phase in the thermoplastic
20 elastomer composition of the present invention.
[0062]
As the polyolefin resin (B), a polyolefin resin synthesized
from monomers containing an a-olefin as a main component is preferably
used. As the a-olefin, an a-olefin of 3 or more carbon atoms is
SF-3059
20
preferable, and the same ex-olefin as the ex-olefin shown in the copolymer
rubber (A) is more preferable. Above all, an ex-olefin of 3 to 12
carbon atoms is still more preferable. When the total amount of
structural units of the polyolefin resin (B) is 100% by mol, the
5 structural units derived from the ex-olefin are contained preferably
in amounts of not less than 80% by mol, more preferably not less than
90% by mol. The polyolefin resin (B) may be a homopolymer of an ex-olefin,
or may be a copolymer of two or more ex-olefins, or may be a copolymer
of an ex-olefin and a monomer which is not an ex-olefin. Further, the
10 polyolefin resin may be a mixture of two or more different kinds of
these polymers, or may be a mixture of two or more different kinds
of these copolymers, or may be a mixture of such a polymer and such
a copolymer. As the polyolefin resin (B), a commercial product may
be used, or the polyolefin resin (B) may be produced by a well-known
15 process using a Ziegler-Natta catalyst or a metallocene catalyst.
[0063)
The maximum peak temperature of the polyolefin resin (B)
determined by differential scanning calorimetry, that is, melting
point (also referred to as "Tm" simply hereinafter) is preferably
20 not lower than 100oC, more preferably not lower than 120°C. If Tm
is lower than 100 OC, sufficient heat resistance and strength are not
exhibited in some cases. The melt flow rate (at a temperature of
230 OC under a load of 2.16 kg) (referred to as "MFR" simply hereinafter)
is preferably 0.1 to 100 g/10 min, more preferably 0.5 to 80 g/10
SF-3059
21
min. If MFR is less than 0.1 g/10 min, kneading processability and
extrusion processability of the elastomer composition sometimes
become insufficient. On the other hand, if MFR exceeds 100 g/10 min,
strength is sometimes lowered.
5 [0064]
The thermoplastic elastomer composition of the present
invention contains the ethylene/a-olefin/non-conjugated polyene
copolymer (A) and the polyolefin resin (B) preferably in a (A)/(B)
mass ratio of 90/10 to 10/90, more preferably 85/15 to 30/70, still
10 more preferably 80/20 to 40/60. When the mass ratio is in the above
range, the balance between rubber elasticity and mechanical properties
tends to become good.
[0065]
The softener (C) can be used in two embodiments of an embodiment
15 (c1) which is a softener having been dispersed in advance in the
ethylene/a-olefin/non-conjugated polyene copolymer (A) and an
embodiment (c2) which is a softener used together with the polyolefin
resin (B) .
20
[0066]
As the softener (C) for use in the present invention, a softener
usually used for rubbers can be used in any of the above embodiments
(c1) and (c2). Specific examples of such softeners include
petroleum-based substances, such as process oil, lubricating oil,
paraffin, liquid paraffin, petroleum asphalt and vaseline; coal tars,
SF-3059
22
such as coal tar and coal tar pitch; fatty oils, such as castor oil,
linseed oil, rapeseed oil, soybean oil and coconut oil; waxes, such
as tall oil, beeswax, carnauba wax and lanoline; fatty acids or metal
salts thereof, such as ricinolic acid, palmitic acid, stearic acid,
5 barium stearate and calcium stearate; synthetic polymer materials,
such as petroleum resin, coumarone-indene resin and atactic
polypropylene; ester-based plasticizers, such as dioctyl phthalate,
dioctyl adipate and dioctyl sebacate; and other substances, such as
microcrystalline wax, factice, liquid polybutadiene, modified liquid
10 polybutadiene and liquid Thiokol. Of these, preferable are process
oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt,
vaseline, etc. from the viewpoint of affinity for the
ethylene/~-olefin/non-conjugated polyene copolymer rubber.
15
[ 0067]
The amount of the softener (C) (total amount of the softener
used in the embodiment (cl) and the softener used in the embodiment
(c2)) is 1 to 200 parts by mass, preferably 30 to 100 parts by mass,
based on 100 parts by mass of the total of the
ethylene/~-olefin/non-conjugated polyene copolymer (A) and the
20 polyolefin resin (B) . When the softener is used in such an amount
as above, fluidity of the thermoplastic elastomer composition can
be sufficiently improved without lowering sealing properties of a
molded product. As the softener, only a softener in the embodiment
(c2) may be used, or only a softener in the embodiment (cl) may be
SF-3059
23
used, or both of a softener in the embodiment (cl) and a softener
in the embodiment (c2) may be used.
[0068]
Examples of the crosslinking agents (D) include an organic
5 peroxide, sulfur, a sulfur compound, and a phenol-based vulcanizing
agent such as phenolic resin. Of these, an organic peroxide is
preferable.
[0069]
Specific examples of the organic peroxides include dicumyl
10 peroxide, di-tert-butyl peroxide,
2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane,
2,5-dimethyl-2,5-di-(tert-butylperoxy)-3-hexyne,
1,3-bis(tert-butylperoxyisopropyl)benzene,
1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane,
15 n-butyl-4,4-bis(tert-butylperoxy)valerate, benzoyl peroxide,
p-chlorobenzoyl peroxide, 2, 4-dichlorobenzoyl peroxide, tert-butyl
peroxybenzoate, tert-butylperobenzoate, tert-butylperoxyisopropyl
carbonate, diacetyl peroxide, lauroyl peroxide and tert-butyl cumyl
peroxide.
20 [0070]
Of these, 2,5-dimethyl-2,5-di-(tert-butylperoxy)hexane,
2,5-dimethyl-2,5-di-(tert-butylperoxy)-3-hexyne,
1,3-bis(tert-butylperoxyisopropyl)benzene,
1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane and
5
SF-3059
24
n-butyl-4,4-bis(tert-butylperoxy)valerate are preferable from the
viewpoints of odor properties and scorch stability, and of these,
1,3-bis(tert-butylperoxyisopropyl)benzene is most preferable.
[0071]
For the purpose of increasing the degree of crosslinking of
the ethylene/a-olefin/non-conjugated polyene copolymer (A), the
crosslinking agent (D) is used preferably in an amount of 0.01 to
3.0 parts by mass, more preferably 0.03 to 2.0 parts by mass, still
more preferably 0. 05 to 1. 5 parts by mass, based on 100 parts by mass
10 of the total amount of the ethylene/a-olefin/non-conjugated polyene
copolymer (A) and the polyolefin resin (B) .
[ 0072]
The thermoplastic elastomer composition of the present
invention may contain a crosslinking assistant (E) .
15 [0073]
Specific examples of the crosslinking assistants (E) include
assistants for peroxy cross linking, such as sulfur, p-quinonedioxime,
p,p'-dibenzoyl quinonedioxime, N-methyl-N,4-dinitrosoaniline,
nitrosobenzene, diphenylquanidine, bismaleimide and
20 trimethylolpropane-N,N'-m-phenylenedimaleimide; polyfunctional
methacrylate monomers, such as divinylbenzene, triallyl cyanurate,
ethylene glycol dimethacrylate, diethylene glycol dimethacrylate,
polyethylene glycol dimethacrylate, trimethylolpropane
tremethacrylate and ally methacrylate; and polyfuncitonal vinyl
SF-3059
25
monomers, such as vinyl butyrate and vinyl stearate.
[0074]
By using such crosslinking assistants, homogeneous and mild
crosslinking reaction can be expected. Of these crosslinking
5 assistants, preferable are triallyl cyanurate, ethylene glycol
dimethacrylate, di vinylbenzene and bismaleimide. These are easy to
handle and have good compatibility with the
ethylene/a-olefin/non-conjugated polyene copolymer (A) and the
polyolefin resin (B) which are main components of the crosslinking
10 treatment object. Moreover, these crosslinking assistants have an
action to solubilize the organic peroxide and function as dispersing
agents for the organic peroxide, so that the crosslinking effect due
to heat treatment is homogeneous, and an olefin-based thermoplastic
elastomer composition having a good balance between fluidity and other
15 properties is obtained.
[0075]
For the purpose of increasing the degree of crosslinking of
the ethylene/a-olefin/non-conjugated polyene copolymer (A), the
crosslinking assistant (E) is used preferably in an amount of 0.1
20 to 3. 0 parts by mass based on 100 parts by mass of the total amount
of the ethylene/a-olefin/non-conjugated polyene copolymer (A) and
the polyolefin resin (B) . When the amount of the crosslinking
assistant (E) compounded is in the above range, the crosslinking
assistant does not remain in the resulting thermoplastic elastomer
SF-3059
26
composition as an unreacted monomer. Therefore, change of properties
due to heat history does not occur during the molding process, and
moreover, the thermoplastic elastomer composition is excellent in
fluidity.
5 [0076]
The thermoplastic elastomer composition of the present
invention can further contain hitherto known additives, such as heat
stabilizer, weathering stabilizer, anti-aging agent, antistatic
agent, filler and colorant, within limits not detrimental to the object
10 of the present invention.
[0077]
The thermoplastic elastomer composition of the present
invention is obtained by kneading the above components (A) to (D)
by the use of the aforesaid batch mixer and thereby carrying out dynamic
15 crosslinking. This dynamic crosslinking is carried out under the
conditions satisfying the aforesaid requirements (1) to (4).
[0078]
The kneading temperature is usually 125 to 280oC, preferably
145 to 240°C. The kneading time, as measured from the time when the
20 cross linking agent (D) has been introduced, is usually 1 to 30 minutes,
preferably 1 to 20 minutes. In this kneading, it is preferable to
add an antioxidant. The shear force applied in the kneading process
is usually in the range of 1 to 104 sec-1
, preferably 10 to 104 sec-1
,
in terms of shear rate.
SF-3059
27
[0079]
As previously described, prior to the introduction of the
crosslinking agent (D), the softener (C) and the
ethylene/~-olefin/non-conjugated polyene copolymer (A) have been
5 kneaded with each other. Here, the softener (C) may have been kneaded
in advance into the ethylene/~-olefin/non-conjugated polyene
copolymer (A). Further, an ethylene/a-olefin/non-conjugated
polyene copolymer (A') wherein the softener (C) has been kneaded into
the ethylene/~-olefin/non-conjugated polyene copolymer (A) may be
10 used in combination.
[0080]
The thermoplastic elastomer composition of the present
invention is a composition in which the
ethylene/a-olefin/non-conjugated polyene copolymer (A) is
15 microdispersed as an island phase in a sea phase composed of the
polyolefin resin (B) . When dynamic crosslinking is carried out using
a batch mixer under the conditions satisfying the aforesaid
requirements (1) to (4), it is possible to sufficiently carry out
dispersingoftheislandphase,aspreviouslydescribed,andtherefore,
20 the thermoplastic elastomer composition of the present invention
suffers little occurrence of a gel-like substance, has good appearance
andhasexcellentmechanicalproperties. Further,theextruderoutput
can be increased.
[0081]
SF-3059
28
In the present invention, use of a batch mixer makes it possible
to accurately control various kneading parameters shown in the
aforesaid requirements (1) to (3). Moreover, by carrying out
crosslinking after the composition temperature is lowered by the
5 introduction of the softener, a composition in which the island phase
has been microdispersed better than that in the conventional products
is obtained. Since this composition has higher viscosity than the
conventionalproducts,theappearanceofamoldedproductisexcellent,
and the extruder output is increased.
10 [0082]
In the thermoplastic elastomer composition of the present
invention, it is preferable that the average particle diameter dn
of circle equivalents of the island phase, as obtained by image analysis
of a photomicrograph observed with an electron microscope (EM), is
15 not more than 5 ~ and the particle size distribution dv/dn of the
island phase (dv: volume average particle diameter of circle
equivalents of the island phase) is not more than 1. 5. dn is preferably
not more than 4 ~' more preferably not more than 2 pm. dn in this
range is preferable from the viewpoint of improvement in rubber
20 elasticity. The particle size distribution dv /dn of the rubber island
phase is preferably not more than 1. 45, more preferably not more than
1.4. dv/dn in this range is preferable from the viewpoint of
improvement in rubber elasticity.
[0083]
SF-3059
29
From the thermoplastic elastomer composition of the present
invention, molded products can be produced by well-known molding
methods, e.g., various molding methods, such as extrusion molding,
press molding, injection molding, calendering and blow molding.
5 Molded products are used for automotive parts, industrial machine
parts, electrical and electronic parts, civil engineering and
construction parts, medical parts, etc., and can be utilized for
materials requiring flexibility, mechanical strength, shape recovery
properties, impact resilience, etc., and in particular, they can be
10 utilized for skin materials.
15
[ 008 4]
The thermoplastic elastomer produced by the production process
of the present invention can be processed into a foam body by the
use of a known foaming method.
Examples
[ 008 5]
In the following examples and comparative examples, measurement
of properties of the thermoplastic elastomer composition and
20 evaluation of appearance of the molded product were carried out by
the following methods.
[Property measurement]
[Melt flow rate (MFR)]
Melt flow rate was measured at 230oC under a load of 10 kg in
SF-3059
30
accordance with ASTM 01238.
[0086]
[Tensile strength (TB), Elongation (EB)]
The thermoplastic elastomer composition was subjected to press
5 molding at 210'C to prepare a pressed sheet having a length of 200
mm, a width of 200 mm an a thickness of 2 mm, and a dumbbell (JIS
No. 3) specimen was prepared by punching it from this pressed sheet.
Using this specimen, a tensile strength (TB) and an elongation (EB)
were measured at a pulling rate of 500 mm/min in accordance with JIS
10 K6251 (2010).
[0087]
[Compression set (CS)]
A press-molded sheet prepared from the thermoplastic elastomer
composition by the use of a press-molding machine was compressed by
15 25% using a spacer in accordance with JIS K6262 and subjected to heat
treatment at 70'C for 24 hours. After the treatment, the sheet was
allowed to stand for 30 minutes in a constant temperature room at
23'C. Thereafter, the thickness of the sheet was measured, and a
compression set (CS) was determined by the following formula.
20 CS = [(t0-tl)/(t0-t2)]x100
CS: compression set (%)
tO: original thickness (mm) of the press-molded sheet
tl: thickness (mm) of the press-molded sheet after allowed to
stand for 30 minutes
SF-3059
31
t2: thickness (mm) of the press-molded sheet under application
of compression strain
[llMelt density]
Melt density of the thermoplastic elastomer composition was
5 measured at 200'C in accordance with JIS K6262, and using a density
at 23'C, the llmelt density (200'C) was calculated from the following
formula.
10
[0088]
[Math. 10]
llMelt density (200'C) (%) = (melt density (200'C)/density
(23 'C)) xlOO
[Extruder output]
The thermoplastic elastomer composition was fed to a single
screw extruder equipped with a die of 25mmxlmm at the opening and
15 having a full-flighted screw having a screw diameter of 50 mm, L/D
of 31 and a compression ratio of 3. 1, and the thermoplastic elastomer
was extruded for 36 seconds while the temperature of the region from
the introductory part of the extruder to the die exit was set at 160'C
to 200'C. From the weight of the composition extruded, an extruder
20 output per hour was calculated.
[0089]
[Appearance evaluation of molded product]
The number of protrusions with a diameter of not less than 0. 8
mm observed on a surface of a molded product of a flat belt extruded
5
SF-3059
32
from the extruder in the above extruder output test was measured per
m of a length of the molded product, and the appearance of the molded
product was evaluated by the number of the protrusions.
[0090]
[Example 1]
Into an intermeshing mixer (manufactured by
harburg-Freudenberger Maschinenbau GmbH, INTERMIX (registered
trademark) GK45E), 78 parts by mass of an
ethylene/a-olefin/non-conjugated polyene copolymer rubber (EPDM)
10 (trade name: MITSUI EPT 3072EPM (manufactured by Mitsui Chemicals,
Inc. ) , 22 parts by mass of a crystalline polyolefin-based resin ( PP-1)
(tradename: EL-ProP740J (manufacturedbySCGChemicals) and15parts
by mass of a crystalline polyolefin-based resin (PP-2) (trade name:
Polypropylene Resin B241 (Prime Polymer Co., Ltd.) were introduced,
15 and while kneading, the temperature was raised up to 175'C from room
temperature to prepare a resin/rubber composition.
[0091]
Subsequently, 0.2 part by mass of a phenol-based antioxidant
(trade name: Irganox 1010 (manufactured by BASF)) and 32 parts by
20 mass of a softener (trade name: Diana Process Oil PW-100 (manufactured
by Idemi tsu Kosan Co., Lid. ) ) were introduced into the intermeshing
mixer, and while kneading, the temperature was lowered down to 135 'C.
[0092]
Thereafter, 0.40 part by mass of an organic peroxide-based
SF-3059
33
crosslinking agent (trade name: PERHEXA 25B (manufactured by NOF
Corporation)) and 0.16 part by mass of a divinylbenzene-based
crosslinking assistant (trade name: DVB-810 (manufactured by NS
Styrene Monomer Co., Ltd.)) were introduced into the intermeshing
5 mixer and kneaded to obtain a thermoplastic elastomer composition.
[0093]
After the introduction of the crosslinking agent, rotational
speed, kneading time and kneading temperature pattern were determined
so that P1 in the requirement (1) might become 104.9 and the average
10 resin temperature might become 162 oc, and cross linking reaction was
carried out to obtain a thermoplastic elastomer composition. The
kneading time (residence time) after the introduction of the
cross1inking agent was 540 seconds, P2 in the requirement (2) was
1189, and P3 in the requirement (3) was -1.1.
15 [0094]
20
In the above operations, the capacity of the intermeshing mixer
was 49 liters, and the charge weight per batch was 36 kg (filling
ratio: 85%).
[0095]
The results of the property measurement of the resulting
thermoplastic elastomer composition and the evaluation of appearance
of the molded product are set forth in Table 1.
[Example 2]
A thermoplastic elastomer composition was obtained under the
5
SF-3059
34
same conditions as in Example 1, except that PERHEXYNE 25B (trade
name, manufactured by NOF Corporation) was used instead of PERHEXA
25B as the organic peroxide-based crosslinking agent. In this case,
P3was-1.6.
[Comparative Example 1]
A resin/rubber composition was prepared in the same manner as
in Example 1.
[ 0096]
Subsequently, 0.2 part by mass of a phenol-based antioxidant
10 (trade name: Irganox 1010 (manufactured by BASF) ) was introduced into
theintermeshingmixer,andwhilekneading,thetemperaturewaslowered
down to 135'C.
[0097]
Thereafter, 0.40 part by mass of an organic peroxide-based
15 crosslinking agent (trade name: PERHEXA 25B (manufactured by NOF
Corporation)) and 0.16 part by mass of a divinylbenzene-based
crosslinking assistant (trade name: DVB-810 (manufactured by NS
Styrene Monomer Co., Ltd.)) were introduced into the intermeshing
mixer and kneaded.
20 [0098]
Thereafter, 32 parts by mass of a softener (trade name: Diana
Process Oil PW-100 (manufactured by Idemitsu Kosan Co., Lid.)) were
introduced into the intermeshing mixer and kneaded to obtain a
thermoplastic elastomer composition.
SF-3059
35
[0099]
After the introduction of the crosslinking agent, rotational
speed, kneading time and kneading temperature pattern were determined
so that P1 in the requirement (1) might become 106.3 and the average
5 resin temperature might become 161"C, and crosslinking reaction was
carried out to obtain a thermoplastic elastomer composition. The
kneading time (residence time) after the introduction of the
crosslinking agent was 555 seconds, P2 in the requirement (2) was
1191, and P3 in the requirement (3) was -1.1.
10 [0100]
15
In the above operations, the capacity of the intermeshing mixer
was 49 liters, and the charge weight per batch was 36 kg (filling
ratio: 85%).
[0101]
The results of the property measurement of the resulting
thermoplastic elastomer composition and the evaluation of appearance
of the molded product are set forth in Table 1.
[Comparative Examples 2 to 7]
Thermoplastic elastomers were obtained in the same formulation
20 and conditions as in Example 1, except that the kneading conditions
were changed so that the parameters P1, P2 and P3 might become the
numerical values shown in Table 1.
[0102]
The results of the property measurement of the resulting
5
10
15
20
SF-3059
36
thermoplastic elastomer compositions and the evaluation of appearance
of the molded products are set forth in Table 1.
[0103]
[Table 1]
SF-3059
37
Ex. I Ex.2 Comp.Ex. I Comp. Ex. 2 Comp. Ex. 3 Comp. Ex. 4 Comp. Ex. 5 Comp. Ex. 6 Comp.Ex. 7
Timing for introduction of softener (C)
(based on introduction of crosslinking before before after before before before before before before
agent)
Crosslinking agent PERHEXA PERHEXYNE PERHEXA PERHEXA PERHEXA PERHEXA PERHEXA PERHEXA PERHEXA
PI 104.9 105.4 106.3 105.3 107.7 308.6 104.7 103.5 41.1
P2 1189 1195 1191 1408 1503 1266 1003 875 1249
P3 -1.1 -1.6 -1.1 1.7 1.4 0.2 -2.8 -2.0 -0.9
Average resin temperature Tave ("C) 162 163 161 238 220 195 128 !55 162
Kneading time tl (sec) after introduction
540 549 555 570 lllO 510 316 Ill 740
of crosslinking agent
1B (MPa) 4.8 5.1 4.7 4.0 4.0 4.1 4.4 4.4 4.9
EB(%) 500 520 500 380 400 390 480 470 510
CS(%) 42 39 41 40 40 41 56 53 39
MFR 31 33 79 82 81 78 28 21 20
Mfelt density(%) 90.2 90.2 86.8 90.2 90.2 90.2 90.2 90.2 90.2
Extruder output (kg/h) 13.1 13.2 11.5 13 13.1 13.1 13 13.3 12.8
Appearance of molded product
29 24 37 110 38 28 35 98 120
(number of protrusions)
5

CLAIMS
[Claim 1)
A thermoplastic elastomer composition obtained by dynamically
cross linking
an ethylene/a-olefin/non-conjugated polyene copolymer (A),
a polyolefin resin (B),
a softener (C) in an amount of 1 to 200 parts by mass per 100
parts by mass of the total of the copolymer (A) and the resin (B),
and
a crosslinking agent (D),
by the use of a batch mixer under the conditions satisfying
the following requirements (1) to (4):
(1) 50~P1~300
wherein P1 is defined by the following formula (i):
[Math. 1)
P1 = yave.xLog(t1) ( i)
wherein the residence time (sec) after the introduction of the
crosslinking agent (D) is denoted as t1 sec, and the average rate
(sec-1
) of shear rates y in the t1 is denoted as yave. sec-1
,
(2) 900~P2~1450
wherein P2 is defined by the following formula (ii):
[Math. 2)
P2 = (Tave.+273)xLog(t1) (ii)
wherein the average resin temperature ('C) after the introduction
SF-3059
39
of the crosslinking agent (D) is denoted as Tave. ·c, and the residence
time (sec) after the introduction of the crosslinking agent (D) is
denoted as t1 sec,
( 3) -2 . 5:>:P3:>:1. 5
5 wherein P3 is defined by the following formula (iii):
[Math. 3]
P3 = Log(t1/t2) (iii)
wherein the residence time (sec) after the introduction of the
cross linking agent (D) is denoted as t1 sec, and the time (sec) required
10 for the residual amount of the crosslinking agent (D) to become not
more than 1 ppm of the introduction amount thereof at the average
resin temperature Tave. after the introduction of the crosslinking
agent (D) is denoted as t2 sec, and
(4) the crosslinking agent (D) is introduced into the batch
15 mixer after the ethylene/a-olefin/non-conjugated polyene copolymer
(A), the polyolefin resin (B) and the softener (C) have been introduced.
[Claim 2]
The thermoplastic elastomer composition as claimed in claim
20 1, wherein the ethylene/a-olefin/non-conjugated polyene copolymer
(A) and the polyolefin resin (B) are contained in a mass ratio ((A) I (B) )
of 90/10 to 10/90.
[Claim 3]
SF-3059
40
The thermoplastic elastomer composition as claimed in claim
1 or 2, wherein the crosslinking agent (D) is an organic peroxide,
and the amount of the crosslinking agent (D) compounded is 0.01 to
3. 0 parts by mass per 100 parts by mass of the total of the copolymer
5 (A) and the resin (B) •
10
15
20
[Claim 4]
The thermoplastic elastomer composition as claimed in any one
of claims 1 to 3, wherein the batch mixer is an intermeshing mixer.
[Claim 5]
A production process for a thermoplastic elastomer composition,
comprising dynamically crosslinking
an ethylene/a-olefin/non-conjugated polyene copolymer (A),
a polyolefin resin (B),
a softener (C) in an amount of 1 to 200 parts by mass per 100
parts by mass of the total of the copolymer (A) and the resin (B),
and
a crosslinking agent (D),
by the use of a batch mixer under the conditions satisfying
the following requirements (1) to (4):
(1) 50:>:P1~3oo
wherein Pl is defined by the following formula (i):
[Math. 1]
5
SF-3059
41
Pl = yave.xLog(tl) ( i)
wherein the residence time (sec) after the introduction of the
crosslinking agent (D) is denoted as tl sec, and the average rate
(sec-1
) of shear rates y in the tl is denoted as yave. sec-(2) 900:>P2:>1450
wherein P2 is defined by the following formula (ii):
[Math. 2)
P2 = (Tave.+273)xLog(tl) (ii)
wherein the average resin temperature ("C) after the introduction
10 of the cross linking agent (D) is denoted as Tave. ·c, and the residence
time (sec) after the introduction of the crosslinking agent (D) is
denoted as tl sec,
15
(3) -2. 5:>p3:>1. 5
wherein P3 is defined by the following formula (iii):
[Math. 3)
P3 = Log(tl/t2) (iii)
wherein the residence time (sec) after the introduction of the
crosslinking agent (D) is denoted as tl sec, and the time (sec) required
for the residual amount of the crosslinking agent (D) to become not
20 more than 1 ppm of the introduction amount thereof at the average
resin temperature Tave. after the introduction of the crosslinking
agent (D) is denoted as t2 sec, and
(4) the crosslinking agent (D) is introduced into the batch
mixer after the ethylene/e~-olefin/non-conjugated polyene copolymer
/
I
SF-3059
42
(A) 1 the polyolefin resin (B) and the softener (C) have been introduced.
[Claim 6]
The production process for a thermoplastic elastomer
5 composition as claimed in claim 51 wherein the mass ratio ((A) I (B))
10
15
20
of the ethylene/a-olefin/non-conjugated polyene copolymer (A) to the
polyolefin resin (B) is 90/10 to 10/90.
[Claim 7]
The production process for a thermoplastic elastomer
··} ,, p composition as claimed in claim 5 or 61 wherein the crosslinking agent
(D) is an organic peroxide, and the amount of the crosslinking agent
(D) compounded is 0.01 to 3.0 parts by mass per 100 parts by mass
of the total of the copolymer (A) and the resin (B) .
···-· .
[Claim 8]
·-..
The pro¢uction process for a thermoplastic elastomer
composition as claimed in any one of claims 5 to 7 1 wherein the batch
mixer is an intermeshing mixer.