Title: Hydrogenated copolymer
Abstract: Disclosed is a hydrogenated copolymer obtained by hydrogenating an unhydrogenated copolymer comprising conjugated diene monomer units and vinyl aromatic monomer units, the unhydrogenated copolymer having at least one polymer block (H) of vinyl aromatic monomer units, wherein the hydrogenated copolymer has the following characteristics (1) to (5): (1) a content of the vinyl aromatic monomer units of from more than 60% by weight to less than 90% by weight, based on the weight of the hydrogenated copolymer; (2) a content of the polymer block (H) of from 1 to 40% by weight, based on the weight of the unhydrogenated copolymer; (3) a weight average molecular weight of from more than 100,000 to 1,000,000; (4) a hydrogenation ratio of 85% or more, as measured with respect to the double bonds in the conjugated diene monomer units; and (5) substantially no crystallization peak observed at -50 to 100.degree. C. in a differential scanning calorimetry (DSC) chart obtained with respect to the hydrogenated copolymer.
Patent Number: 6,852,806 Issued on 02/08/2005 to Sasagawa, et al.
| Inventors:
|
Sasagawa; Masahiro (Yokohama, JP);
Takayama; Shigeki (Tokyo, JP);
Sasaki; Shigeru (Yokohama, JP);
Hisasue; Takahiro (Yokohama, JP);
Suzuki; Katsumi (Kawasaki, JP);
Nakajima; Shigeo (Fujisawa, JP)
|
| Assignee:
|
Asahi Kasei Kabushiki Kaisha (Osaka, JP)
|
| Appl. No.:
|
432194 |
| Filed:
|
May 20, 2003 |
| PCT Filed:
|
October 23, 2002
|
| PCT NO:
|
PCT/JP02/10973
|
| 371 Date:
|
May 20, 2003
|
| 102(e) Date:
|
May 20, 2003
|
| PCT PUB.NO.:
|
WO03/03570 |
| PCT PUB. Date:
|
May 1, 2003 |
Foreign Application Priority Data
| Oct 23, 2001[JP] | 2001-325476 |
| Mar 01, 2002[JP] | 2002-055388 |
| Jun 28, 2002[JP] | 2002-189562 |
| Jul 15, 2002[JP] | 2002-205350 |
| Current U.S. Class: |
525/332.9; 428/500; 521/148; 525/98; 525/314; 525/338 |
| Intern'l Class: |
C08F 008/04 |
| Field of Search: |
525/98,314,332.9,338
521/148
428/500
|
References Cited [Referenced By]
U.S. Patent Documents
| 4226952 | Oct., 1980 | Halasa et al.
| |
| 4501857 | Feb., 1985 | Kishimoto et al. | 525/338.
|
| 4673714 | Jun., 1987 | Kishimoto et al.
| |
| 5109069 | Apr., 1992 | Shibata et al.
| |
| 5331058 | Jul., 1994 | Shepherd et al.
| |
| 5527753 | Jun., 1996 | Engel et al.
| |
| 5702810 | Dec., 1997 | Koseki et al.
| |
| 5708092 | Jan., 1998 | Schwindeman et al.
| |
| Foreign Patent Documents |
| 42-8704 | Apr., 1967 | JP.
| |
| 3-185058 | Aug., 1991 | JP.
| |
| 3-188114 | Aug., 1991 | JP.
| |
| 6-287365 | Oct., 1994 | JP.
| |
| 6-287229 | Nov., 1994 | JP.
| |
| 8-109219 | Apr., 1996 | JP.
| |
| 2000-297183 | Oct., 2000 | JP.
| |
| WO98/12240 | Mar., 1998 | WO.
| |
Primary Examiner: Teskin; Fred
Attorney, Agent or Firm: Birch, Stewart, Kolasch & Birch, LLP
Parent Case Text
This application is the national phase under 35 U.S.C. .sctn.371 of PCT
International Application No. PCT/JP02/10973 which has an International
filing date of Oct. 23, 2002, which designated the United States of
America.
Claims
What is claimed is:
1. A hydrogenated copolymer obtained by hydrogenating an unhydrogenated
copolymer comprising conjugated diene monomer units and vinyl aromatic
monomer units, said unhydrogenated copolymer having at least one polymer
block (H) of vinyl aromatic monomer units,
said hydrogenated copolymer having the following characteristics (1) to
(5):
(1) a content of said vinyl aromatic monomer units of from more than 60% by
weight to less than 90% by weight, based on the weight of said
hydrogenated copolymer,
(2) a content of said polymer block (H) of from 1 to 40% by weight, based
on the weight of said unhydrogenated copolymer,
(3) a weight average molecular weight of from more than 100,000 to
1,000,000,
(4) a hydrogenation ratio of 85% or more, as measured with respect to the
double bonds in said conjugated diene monomer units, and
(5) substantially no crystallization peak observed at -50 to 100.degree. C.
in a differential scanning calorimetry (DSC) chart obtained with respect
to said hydrogenated copolymer.
2. The hydrogenated copolymer according to claim 1, wherein said
unhydrogenated copolymer is a block copolymer selected from the group
consisting of block copolymers which are, respectively, represented by the
following formulae:
S--H (1),
S--H--S (2),
(S--H).sub.m --X (3) and
(S--H).sub.n --X--(H).sub.p (4),
wherein each S independently represents a random copolymer block comprised
of said conjugated diene monomer units and said vinyl aromatic monomer
units, each H independently represents a polymer block of vinyl aromatic
monomer units, each X independently represents a residue of a coupling
agent, m represents an integer of 2 or more, and each of n and p
independently represents an integer of 1 or more.
3. The hydrogenated copolymer according to claim 2, wherein said
unhydrogenated copolymer is a block copolymer represented by said formula
(1).
4. The hydrogenated copolymer according to any one of claims 1 to 3, which
is a foam.
5. The hydrogenated copolymer according to any one of claims 1 to 3, which
is a shaped article.
6. The hydrogenated copolymer according to claim 5, which is a multilayer
film or a multilayer sheet.
7. The hydrogenated copolymer according to claim 5, which is a shaped
article produced by a method selected from the group consisting of an
extrusion molding, an injection molding, a blow molding, air-pressure
molding, a vacuum molding, a foam molding, a multilayer extrusion molding,
a multilayer injection molding, a high frequency weld molding and a slush
molding.
8. The hydrogenated copolymer according to any one of claims 1 to 3, which
is a building material, a vibration damping, soundproofing material or an
electric wire coating material.
9. A crosslinked hydrogenated copolymer obtained by subjecting the
hydrogenated copolymer of any one of claims 1 to 3 to a crosslinking
reaction in the presence of a vulcanizing agent.
10. A hydrogenated copolymer composition comprising:
1 to 99 parts by weight of the hydrogenated copolymer (a) of claim 1, and
99 to 1 part by weight of at least one polymer (b) selected from the group
consisting of a thermoplastic resin other than the hydrogenated copolymer
(a) and a rubbery polymer other than the hydrogenated copolymer (a).
11. The hydrogenated copolymer composition according to claim 10, which is
a foam.
12. The hydrogenated copolymer composition according to claim 10, which is
a shaped article.
13. The hydrogenated copolymer composition according to claim 12, which is
a multilayer film or a multilayer sheet.
14. The hydrogenated copolymer composition according to claim 12, which is
a shaped article produced by a method selected from the group consisting
of an extrusion molding, an injection molding, a blow molding,
air-pressure molding, a vacuum molding, a foam molding, a multilayer
extrusion molding, a multilayer injection molding, a high frequency weld
molding and a slush molding.
15. The hydrogenated copolymer composition according to claim 10, which is
a building material, a vibration damping, soundproofing material or an
electric wire coating material.
16. A crosslinked hydrogenated copolymer composition obtained by subjecting
the hydrogenated copolymer composition of claim 10 to a crosslinking
reaction in the presence of a vulcanizing agent.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hydrogenated copolymer. More
particularly, the present invention is concerned with a hydrogenated
copolymer obtained by hydrogenating an unhydrogenated copolymer comprising
conjugated diene monomer units and vinyl aromatic monomer units, the
unhydrogenated copolymer having at least one polymer block (H) of vinyl
aromatic monomer units, wherein the content of the vinyl aromatic monomer
units, content of the polymer block (H), weight average molecular weight,
and hydrogenation ratio (as measured with respect to the double bonds in
the conjugated diene monomer units) of the hydrogenated copolymer are,
respectively, within specific ranges, and substantially no crystallization
peak is observed at -50 to 100.degree. C. in a differential scanning
calorimetry (DSC) chart obtained with respect to the hydrogenated
copolymer. The hydrogenated copolymer of the present invention not only
has excellent flexibility, impact resilience and scratch resistance, but
also has excellent handling property (anti-blocking property). The
"anti-blocking property" means a resistance to adhesion phenomena (which
is generally referred to as "blocking") wherein when, for example, stacked
resin shaped articles or a rolled resin film (which have or has resin
surfaces which are in contact with each other) are or is stored for a long
time, unfavorably strong adhesion occurs between the resin surfaces, so
that it becomes difficult to separate the resin surfaces from each other.
Further, the present invention also relates to a hydrogenated copolymer
composition comprising the above-mentioned hydrogenated copolymer (a), and
at least one polymer (b) selected from the group consisting of a
thermoplastic resin other than the hydrogenated copolymer (a) and a
rubbery polymer other than the hydrogenated copolymer (a). The
hydrogenated copolymer composition comprising the excellent hydrogenated
copolymer of the present invention exhibits excellent properties, such as
high impact resistance, moldability and abrasion resistance. Each of the
hydrogenated copolymer and hydrogenated copolymer composition of the
present invention can be advantageously used as a foam, various shaped
articles, a building material, a vibration damping, soundproofing
material, an electric wire coating material and the like.
2. Prior Art
A copolymer comprising a conjugated diene and a vinyl aromatic hydrocarbon
(hereinafter, frequently referred to as a "conjugated diene/vinyl aromatic
hydrocarbon copolymer") has unsaturated double bonds, so that such a
copolymer have poor thermal stability, weatherability and ozone
resistance. As a method for improving these properties of the conjugated
diene/vinyl aromatic hydrocarbon copolymer, there has long been known a
method in which the unsaturated double bonds of the copolymer are
hydrogenated. Such a method is disclosed in, for example, Unexamined
Japanese Patent Application Laid-Open Specification No. Sho 56-30447 and
Unexamined Japanese Patent Application Laid-Open Specification No. Hei
2-36244.
On the other hand, a hydrogenation product of a conjugated diene/vinyl
aromatic hydrocarbon block copolymer exhibits, even if not vulcanized, not
only excellent elasticity at room temperature, which is comparable to that
of a conventional vulcanized natural or synthetic rubber, but also
excellent processibility at high temperatures, which is comparable to that
of a conventional thermoplactic resin. Therefore, the hydrogenated block
copolymer is widely used in various fields, such as modifiers for
plastics, adhesive agents, automobile parts, and parts for medical
equipment. In recent years, it has been attempted to obtain a random
copolymer of a conjugated diene and a vinyl aromatic hydrocarbon, which
has characteristics similar to those of the hydrogenated block copolymer
as mentioned above.
For example, Unexamined Japanese Patent Application Laid-Open Specification
No. Hei 2-158643 (corresponding to U.S. Pat. No. 5,109,069) discloses a
composition containing a hydrogenated diene copolymer and a polypropylene
resin, wherein the hydrogenated diene copolymer is obtained by
hydrogenating a random copolymer of a conjugated diene and a vinyl
aromatic hydrocarbon, which random copolymer has a vinyl aromatic
hydrocarbon content of 3 to 50% by weight, a molecular weight distribution
(weight average molecular weight (Mw)/number average molecular weight
(Mn)) of 10 or less, and a vinyl bond content of 10 to 90% as measured
with respect to the conjugated diene monomer units in the copolymer.
Further, Unexamined Japanese Panent Application Laid-Open Specification
No. Hei 6-287365 discloses a composition containing a hydrogenated diene
copolymer and a polypropylene resin, wherein the hydrogenated diene
polymer is obtained by hydrogenating a random copolymer of a conjugated
diene and a vinyl aromatic hydrocarbon, which random copolymer has a vinyl
aromatic hydrocarbon content of 5 to 60% by weight, and a vinyl bond
content of 60% or more as measured with respect to the conjugated diene
monomer units in the copolymer.
With respect to the above-mentioned hydrogenated diene copolymers, it has
been attempted to use the copolymers as substitutes for a flexible vinyl
chloride resin. The flexible vinyl chloride resin causes environmental
problems, such as generation of halogen gas when the resin is on fire, and
generation of enrivonmental hormones due to the plasticizer used in the
resin. Therefore, there is a pressing need for development of a substitute
material for the flexible vinyl chloride resin. However, the
above-mentioned hydrogenated diene copolymers are unsatisfactory with
resepct to the properies (such as impact resilience, and scratch
resistance) which are needed for a material used as a substitute for the
flexible vinyl chloride resin.
Further, with respect to molding materials containing the above-mentioned
hydrogenated diene copolymer in combination with vairous theremoplastic
resins or rubbers, it has been desired to improve the mechanical strength
and moldability of the hydrogenated diene copolymer.
WO98/12240 discloses a molding material composed mainly of, as a polymer
similar to the vinyl chloride resin, a hydrogenated block copolymer
comprising a polymer block composed mainly of styrene and a polymer block
composed mainly of butadiene and styrene. Further, Unexamined Japanese
Patent Application Laid-Open Specification No. Hei 3-185058 discloses a
resin composition comprising a polyphenylene ether resin, a polyolefin
resin, and a hydrogenation product of a vinyl aromatic
hydrocarbon/conjugated diene copolymer, wherein the same hydrogenated
block copolymer as used in the above-mentioned WO98/12240 is used as the
hydrogenation product of a vinyl aromatic hydrocarbon/conjugated diene
copolymer. However, the hydrogenated copolymer used in each of the
above-mentioned patent documents is a crystalline polymer and, hence, has
poor flexibility and is not suitable for use as a substitute for the
flexible vinyl chloride resin.
Thus, although there has been a pressing need for development of a
substitute material for the flexible vinyl chloride resin, a material
having excellent properties (such as flexibility and scratch resistance)
which are comparable to those of the flexible vinyl chloride resin has not
yet been obtained.
SUMMARY OF THE INVENTION
In this situation, the present inventors have made extensive and intensive
studies with a view toward solving the above-mentioned problems
accompanying the prior art. As a result, it has unexpectedly been found
that the above-menitoned problem can be solved by a hydrogenated copolymer
obtained by hydrogenating an unhydrogenated copolymer comprising
conjugated diene monomer units and vinyl aromatic monomer units, the
unhydrogenated copolymer having at least one polymer block (H) of vinyl
aromatic monomer units, wherein the content of the vinyl aromatic monomer
units, content of the polymer block (H), weight average molecular weight
and hydrogenation ratio (as measured with respect to the double bonds in
the conjugated diene monomer units) of the hydrogenated copolymer are,
respectively, within specific ranges, and substantially no crystallization
peak is observed at -50 to 100.degree. C. in a differential scanning
calorimetry (DSC) chart obtained with respect to the hydrogenated
copolymer.
Accordingly, it is an object of the present invention to provide a
hydrogenated copolymer which not only has excellent flexibility, impact
resilience and scratch resistance, but also has excellent handling
property (anti-blocking property).
It is another object of the present invention to provide a hydrogenated
copolymer composition obtained by blending the above-mentioned
hydrogenated copolymer with a thermoplastic resin and/or rubbery polymer
which are/is other than the hydrogenated copolymer, which composition has
excellent properties, such as high impact resistance, tensile strength,
moldability and abrasion resistance.
The foregoing and other objects, features and advantages of the present
invention will be apparent from the following detailed description and
appended claims taken in connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a chart showing a dynamic viscoelastic spectrum of the
composition obtained in Example 18;
FIG. 2(a) is an explanatroy diagrammatic front view of a powder feeding box
used in Examples 35 and 36 for conducting a slush molding;
FIG. 2(b) is an explanatroy diagrammatic side view of the powder feeding
box of FIG. 2(a);
FIG. 2(c) is an explanatroy diagrammatic view of the powder feeding box of
FIG. 2(a) as viewed from above the powder feeding box;
FIG. 2(d) is an explanatory diagrammatic side view of the powder feeding
box of FIG. 2(a) which contains a powder of the hydrogenated copolymer
composition, and which has attached thereto an electroformed nickel mold
having a granulated inner surface, shown with a partly broken wall of the
box in order to show the interior of the box; and
FIG. 3 is an explanatory diagramatic cross-sectional view of a powder slush
molded article.
DESCRIPTION OF REFERENCE NUMERALS
1. Single-shaft rotation handle
2. Revolution shaft
3. Powder feeding box
4. Electroformed nickel mold having a granulated inner surface
5. Hydrogenated copolymer composition powder
6. Flat portion of the powder slush molded article
7. Undercut portion of the powder slush molded article
DETAILED DESCRIPTION OF THE INVENTION
In one aspect of the present invention, there is provided a hydrogenated
copolymer obtained by hydrogenating an unhydrogenated copolymer comprising
conjugated diene monomer units and vinyl aromatic monomer units, the
unhydrogenated copolymer having at least one polymer block (H) of vinyl
aromatic monomer units,
the hydrogenated copolymer having the following characteristics (1) to (5):
(1) a content of the vinyl aromatic monomer units of from more than 60% by
weight to less than 90% by weight, based on the weight of the hydrogenated
copolymer,
(2) a content of the polymer block (H) of from 1 to 40% by weight, based on
the weight of the unhydrogenated copolymer,
(3) a weight average molecular weight of from more than 100,000 to
1,000,000,
(4) a hydrogenation ratio of 85% or more, as measured with respect to the
double bonds in the conjugated diene monomer units, and
(5) substantially no crystallization peak observed at -50 to 100.degree. C.
in a differential scanning calorimetry (DSC) chart obtained with respect
to the hydrogenated copolymer.
For easy understanding of the present invention, the essential features and
various preferred embodiments of the present invention are enumerated
below.
1. A hydrogenated copolymer obtained by hydrogenating an unhydrogenated
copolymer comprising conjugated diene monomer units and vinyl aromatic
monomer units, the unhydrogenated copolymer having at least one polymer
block (H) of vinyl aromatic monomer units,
the hydrogenated copolymer having the following characteristics (1) to (5):
(1) a content of the vinyl aromatic monomer units of from more than 60% by
weight to less than 90% by weight, based on the weight of the hydrogenated
copolymer,
(2) a content of the polymer block (H) of from 1 to 40% by weight, based on
the weight of the unhydrogenated copolymer,
(3) a weight average molecular weight of from more than 100,000 to
1,000,000,
(4) a hydrogenation ratio of 85% or more, as measured with respect to the
double bonds in the conjugated diene monomer units, and
(5) substantially no crystallization peak observed at -50 to 100.degree. C.
in a differential scanning calorimetry (DSC) chart obtained with respect
to the hydrogenated copolymer.
2. The hydrogenated copolymer according to item 1 above, wherein the
unhydrogenated copolymer is a block copolymer selected from the group
consisting of block copolymers which are, respectively, represented by the
following formulae:
S--H (1),
S--H--S (2),
(S--H).sub.m --X (3)
and
(S--H).sub.n --X--(H).sub.p (4),
wherein each S independently represents a random copolymer block comprised
of conjugated diene monomer units and vinyl aromatic monomer units, each H
independently represents a polymer block of vinyl aromatic monomer units,
each X independently represents a residue of a coupling agent, m
represents an integer of 2 or more, and each of n and p independently
represents an integer of 1 or more.
3. The hydrogenated copolymer according to item 2 above, wherein the
unhydrogenated copolymer is a block copolymer represented by the formula
(1).
4. The hydrogenated copolymer according to any one of items 1 to 3 above,
which is a foam.
5. The hydrogenated copolymer according to any one of items 1 to 3 above,
which is a shaped article.
6. The hydrogenated copolymer according to item 5 above, which is a
multilayer film or a multilayer sheet.
7. The hydrogenated copolymer according to item 5 above, which is a shaped
article produced by a method selected from the group consisting of an
extrusion molding, an injection molding, a blow molding, air-pressure
molding, a vacuum molding, a foam molding, a multilayer extrusion molding,
a multilayer injection molding, a high frequency weld molding and a slush
molding.
8. The hydrogenated copolymer according to any one of items 1 to 3 above,
which is a building material, a vibration damping, soundproofing material
or an electric wire coating material.
9. A crosslinked, hydrogenated copolymer obtained by subjecting the
hydrogenated copolymer of any one of items 1 to 3 above to a crosslinking
reaction in the presence of a vulcanizing agent.
10. A hydrogenated copolymer composition comprising:
1 to 99 parts by weight of the hydrogenated copolymer (a) of item 1 above,
and
99 to 1 part by weight of at least one polymer (b) selected from the group
consisting of a thermoplastic resin other than the hydrogenated copolymer
(a) and a rubbery polymer other than the hydrogenated copolymer (a).
11. The hydrogenated copolymer composition according to item 10 above,
which is a foam.
12. The hydrogenated copolymer composition according to item 10 above,
which is a shaped article.
13. The hydrogenated copolymer composition according to item 12 above,
which is a multilayer film or a multilayer sheet.
14. The hydrogenated copolymer composition according to item 12 above,
which is a shaped article produced by a method selected from the group
consisting of an extrusion molding, an injection molding, a blow molding,
air-pressure molding, a vacuum molding, a foam molding, a multilayer
extrusion molding, a multilayer injection molding, a high frequency weld
molding and a slush molding.
15. The hydrogenated copolymer composition according to item 10 above,
which is a building material, a vibration damping, soundproofing material
or an electric wire coating material.
16. A crosslinked, hydrogenated copolymer composition obtained by
subjecting the hydrogenated copolymer composition of item 10 above to a
crosslinking reaction in the presence of a vulcanizing agent.
Hereinbelow, the present invention is described in detail.
In the present invention, the monomer units of the polymer are named in
accordance with a nomenclature wherein the names of the original monomers
from which the monomer units are derived are used with the term "unit"
attached thereto. For example, the term "vinyl aromatic monomer unit"
means a monomer unit which is formed in a polymer obtained by the
polymerization of the vinyl aromatic monomer. The vinyl aromatic monomer
unit has a molecular structure wherein the two carbon atoms of a
substituted ethylene group derived from a substituted vinyl group
respectively form linkages to adjacent vinyl aromatic monomer units.
Similarly, the term "conjugated diene monomer unit" means a monomer unit
which is formed in a polymer obtained by the polymerization of the
conjugated diene monomer. The conjugated diene monomer unit has a
molecular structure wherein the two carbon atoms of an olefin
corresponding to the conjugated diene monomer respectively form linkages
to adjacent conjugated diene monomer units.
The hydrogenated copolymer of the present invention is obtained by
hydrogenating an unhydrogenated copolymer comprising conjugated diene
monomer units and vinyl aromatic monomer units, and has at least one
polymer block (H) of vinyl aromatic monomer units. The hydrogenated
copolymer of the present invention has a content of the vinyl aromatic
monomer units of from more than 60% by weight to less than 90% by weight,
based on the weight of the hydrogenated copolymer. When the content of the
vinyl aromatic monomer units is more than 60% by weight, the hydrogenated
block copolymer exhibits excellent anti-blocking property (handling
property) and scratch resistance. When the content of the vinyl aromatic
monomer units is less than 90% by weight, the hydrogenated copolymer is
advantageous not only in that it exhibits excellent flexibility and impact
resilience, but also in that a resin composition containing such a
hydrogenated copolymer exhibits excellent impact resistance. The content
of the vinyl aromatic monomer units is preferably in the range of from 62
to 88% by weight, more preferably from 64 to 86% by weight, still more
preferably from 65 to 80% by weight. The content of the vinyl aromatic
monomer units can be measured by means of an ultraviolet
spectrophotometer. In the present invention, the content of the vinyl
aromatic monomers in the copolymer prior to the hydrogenation (i.e.,
unhydrogenated copolymer) may be used as the content of the vinyl aromatic
monomer units in the hydrogenated copolymer of the present invention.
In the hydrogenated copolymer of the present invention, the content of the
polymer block (H) of vinyl aromatic monomer units (hereinafter, frequently
referred to as "vinyl aromatic polymer block (H)) is in the range of from
1 to 40% by weight, based on the weight of the unhydrogenated copolymer.
When the content of the vinyl aromatic polymer block (H) is 1% by weight
or more, the hydrogenated copolymer exhibits excellent anti-blocking
property and impact resilience. When the content of the vinyl aromatic
polymer block (H) is 40% by weight or less, the hydrogenated copolymer
exhibits excellent scratch resistance. In the present invention, the
content of the vinyl aromatic polymer block (H) is preferably in the range
of from 5 to 35% by weight, more preferably from 10 to 30% by weight,
still more preferably from 13 to 20% by weight. In the present invention,
the content of the vinyl aromatic polymer block (H) can be measured by the
following method. The weight of the vinyl aromatic polymer block (H) is
obtained by a method in which the unhydrogenated copolymer is subjected to
oxidative degradation in the presence of osmium tetraoxide as a catalyst
using tert-butyl hydroperoxide (i.e., method described in I. M. KOLTHOFF,
et al., J. Polym. Sci. 1, 429 (1946)) (hereinafter, frequently referred to
as "osmium tetraoxide degradation method"). Using the obtained weight of
the vinyl aromatic polymer block (H), the content of the vinyl aromatic
polymer block (H) in the hydrogenated copolymer is calculated by the
following formula, with the proviso that, among the polymer chains (formed
by the oxidative degradation) corresponding to the vinyl aromatic polymer
blocks (H), the polymer chains having an average polymerization degree of
30 or less are not taken into consideration in the measurement of the
content of the vinyl aromatic polymer block (H).
Content of the vinyl aromatic polymer block (H) (% by weight)=(weight of
the vinyl aromatic polymer block (H) in the copolymer prior to the
hydrogenation/weight of the copolymer prior to the hydrogenation)
.times.100.
In the present invention, the vinyl aromatic polymer block (H) of the
hydrogenated copolymer content can also be measured by a method using a
nuclear magnetic resonance (NMR) apparatus (i.e., NMR method which is
described in Y. Tanaka et al., "RUBBER CHEMISTRY and TECHNOLOGY 54", 685
(1981), published by American Chemical Society, Inc., U.S.A.). However, in
the present invention, the vinyl aromatic polymer block (H) content
measured by the above-mentioned osmium tetraoxide degradation method
(which is simpler than the NMR method) is used as the vinyl aromatic
polymer block (H) content of the hydrogenated copolymer. There is a
correlation between the vinyl aromatic polymer block (H) content
(hereinafter, referred to as an "Os value") obtained by the osmium
tetraoxide degradation method and the vinyl aromatic polymer block (H)
content (hereinafter, referred to as an "Ns value") obtained by the NMR
method. More specifically, as a result of the studies made with respect to
various copolymers having different contents of vinyl aromatic polymer
block (H), it has been found that the above-mentioned correlation is
represented by the following formula:
Os value=-0.012(Ns value).sup.2 +1.8(Ns value)-13.0
In the present invention, when the vinyl aromatic polymer block (H) content
is obtained by the NMR method, the obtained Ns value is converted into the
Os value, utilizing the above-mentioned formula representing the
correlationship between the Os value and the Ns value.
The hydrogenated copolymer of the present invention has a weight average
molecular weight of more than 100,000 and 1,000,000 or less. When the
weight average molecular weight is more than 100,000, the hydrogenated
copolymer exhibits excellent impact resilience and scratch resistance.
When the weight average molecular weight is 1,000,000 or less, the
hydrogenated copolymer exhibits excellent moldability. The weight average
molecular weight of the hydrogenated copolymer is preferably in the range
of from 130,000 to 800,000, more preferably from 150,000 to 500,000. The
weight average molecular weight can be measured by gel permeation
chromatography (GPC) using a calibration curve obtained using a
chromatogram of standard polystyrene samples commercially available (the
calibration curve is obtained by the use of the peak molecular weights of
the standard polystyrene samples).
With respect to the molecular weight distribution of the hydrogenated
copolymer, from the viewpoint of moldability thereof, the molecular weight
distribution is preferably in the range of from 1.5 to 5.0, more
preferably from 1.6 to 4.5, still more preferably from 1.8 to 4.0. The
molecular weight distribution can also be obtained by GPC as in the case
of the measurement of the weight average molecular weight, in terms of a
ratio (Mw/Mn) of the weight average molecular weight (Mw) to the number
average molecular weight (Mn).
In the hydrogenated copolymer of the present invention, the hydrogenation
ratio is 85% or more, as measured with respect to the double bonds in the
conjugated diene monomer units in the hydrogenated copolymer. Due to such
a high hydrogenation ratio of the double bonds of the conjugated diene
monomer units, the hydrogenated copolymer of the present invention
exhibits excellent anti-blocking property and scratch resistance. In the
present invention, the hydrogenation ratio is preferably 90% or more, more
preferably 92% or more, still more preferably 95% or more. With respect to
the copolymer (unhydrogenated copolymer) prior to the hydrogenation, the
vinyl bond content of the conjugated diene monomer units can be measured
by a method (Hampton method) using an infrared spectrometer. The
hydrogenation ratio of the hydrogenated copolymer can be measured by means
of a nuclear magnetic resonance (NMR) apparatus.
The hydrogenated copolymer of the present invention has a characteristic
that substantially no crystallization peak is observed at -50 to
100.degree. C. in a differential scanning calorimetry (DSC) chart obtained
with respect to the hydrogenated copolymer. In the present invention,
"substantially no crystallization peak is observed at -50 to 100.degree.
C." means that no peak indicating the occurrence of crystallization (i.e.,
crystallization peak) is observed within the above-mentioned temperature
range, or that a crystallization peak is observed within the
above-mentioned temperature range but the quantity of heat at the
crystallization peak is less than 3 J/g, preferably less than 2 J/g, more
preferably less than 1 J/g. In the present invention, it is most preferred
that no crystallization peak is observed within the above-mentioned
temperature range. When a hydrogenated copolymer has a crystallization
peak within the above-mentioned temperature range, such a hydrogenated
copolymer has markedly poor flexibility and, hence, is not suitable as a
substitute material for a flexible vinyl chloride resin, which substitute
material is aimed at in the present invention. The hydrogenated copolymer
exhibiting substantially no crystallization peak at -50 to 100.degree. C.
can be obtained by the use of an unhydrogenated copolymer which is
obtained by a polymerization reaction conducted using the below-described
vinyl bond formation-controlling agent under the below-described
conditions.
It is one of the characteristic features of the hydrogenated copolymer of
the present invention that the hydrogenated copolymer exhibits excellent
flexibility, so that the hydrogenated copolymer exhibits an advantageously
low value with respect to the 100% modulus in a tensile test. It is
recommended that the 100% modulus of the hydrogenated polymer of the
present invention is 120 kg/cm.sup.2 or less, preferably 90 kg/cm.sup.2 or
less, more preferably 60 kg/cm.sup.2 or less.
With respect to the structure of the hydrogenated copolymer of the present
invention, there is no particular limitation, and the hydrogenation
copolymer may have any structure. However, as the unhydrogenated copolymer
used in the present invention, it is preferred to use at least one block
copolymer selected from the group consisting of block copolymers
represented by the following formulae (1) to (4):
S--H (1),
S--H--S (2),
(S--H).sub.m --X (3) and
(S--H).sub.n --X--(H).sub.p (4),
wherein each S independently represents a random copolymer block comprised
of conjugated diene monomer units and vinyl aromatic monomer units, each H
independently represents a polymer block of vinyl aromatic monomer units,
each X independently represents a residue of a coupling agent, m
represents an integer of 2 or more, and each of n and p independently
represents an integer of 1 or more.
From the viewpoint of productivity and flexibility of the hydrogenated
copolymer, it is especially preferred to use the block copolymer of the
above-mentioned formula (1).
In the present invention, the hydrogenated copolymer may be in the form of
a mixture of hydrogenated products of at least two block copolymers
selected from the group consisting of the above-mentioned block copolymer
of formulae (1) to (4). Further, the hydrogenated copolymer of the present
invention may be in the form of a mixture thereof with a vinyl aromatic
polymer.
With respect to each of the block copolymers of the above formulae (1) to
(4), there is no particular limitation with respect to the distribution of
the vinyl aromatic monomer units in the random copolymer block S. For
example, the vinyl aromatic monomer units may be uniformly distributed or
may be distributed in a tapered configuration in the random copolymer
block S. The random block copolymer S may have a plurality of segments in
which the vinyl aromatic monomer units are uniformly distributed and/or
may have a plurality of segments in which the vinyl aromatic monomer units
are distributed in a tapered configuration. Further, the random copolymer
block S may have a plurality of segments having different vinyl aromatic
monomer unit contents. In the above-mentioned formula (3), m represents an
integer of 2 or more, more preferably from 2 to 10. In the above-mentioned
formula (4), each of n and p independently represents an integer of 1 or
more, preferably from 1 to 10.
In the present invention, the conjugated diene monomer is a diolefin having
a pair of conjugated double bonds. Examples of conjugated diene monomers
include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene),
2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene and
1,3-hexadiene. Of these, especially preferred are 1,3-butadiene and
isoprene. The above conjugated diene monomer can be used individually or
in combination. Examples of vinyl aromatic monomers include styrene,
.alpha.-methylstyrene, p-methylstyrene, divinylbenzene,
1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene and
N,N-diethyl-p-aminoethylstyrene. These vinyl aromatic monomers can be used
individually or in combination.
In the present invention, the microstructure (including the amounts of a
cis bond, a trans bond, and a vinyl bond) of the conjugated diene monomer
units in the copolymer prior to the hydrogenation can be appropriately
controlled by using the below-described polar compound and the like. When
1,3-butadiene (which is addition-polymerized through a cis-1,4 bond, a
trans-1,4 bond or a 1,2-vinyl bond) is used as the conjugated diene
monomer, it is generally recommended that the 1,2-vinyl bond content is in
the range of from 5 to 80 mol % preferably from 10 to 60 mol %, still more
preferably from 12 to 50 mol %, based on the total molar amount of the
cis-1,4 bond, trans-1,4 bond and 1,2-vinyl bond. For obtaining a copolymer
having excellent flexibility, it is preferred that the 1,2-vinyl bond
content is 12 mol % or more. When isoprene is used as the conjugated diene
monomer, it is generally recommended that the total content of the
1,2-vinyl bond and 3,4-vinyl bond is in the range of from 3 to 75 mol %,
preferably from 5 to 60%, based on the total molar amount of the cis-1,4
bond, trans-1,4 bond, 1,2-vinyl bond and 3,4-vinyl bond. In the present
invention, the total content of the 1,2-vinyl bond and 3,4-vinyl bond (or
the content of the 1,2-vinyl bond in the case where 1,3-butadiene is used
as the conjugated diene monomer) is defined as the vinyl bond content.
Further, in the present invention, from the viewpoint of the desired impact
resilience of the hydrogenated copolymer, it is recommended that the
difference between the maximum value and minimum value of the vinyl bond
content of the unhydrogenated copolymer is 10 mol % or less, preferably 8
mol % or less, more preferably 6 mol % or less. The difference between the
maximum value and minimum value of the vinyl bond content of the
unhydrogenated copolymer can be obtained by the following method. For
example, in the case where the production of the unhydrogenated copolymer
is conducted in a batchwise manner in which monomers are stepwise fed to
the reactor, a sample of the copolymer is taken just before each of the
monomer feeding steps, and the vinyl bond content is measured with respect
to each of the obtained samples. With respect to the obtained values of
the vinyl bond content, the difference between the maximum value and the
minimum value is calculated. In the unhydrogenated copolymer, the vinyl
bonds may be uniformly distributed or may be distributed in a tapered
configuration. The difference in the vinyl bond content between the
above-mentioned samples is caused by the influence of polymerization
conditions, such as the type and amount of the vinyl bond
formation-controlling agent (such as a tertiary amine compound or an ether
compound) and polymerization reaction temperature. Therefore, the
difference between the maximum value and minimum value of the vinyl bond
content of the unhydrogenated copolymer can be controlled by, for example,
adjusting the polymerization reaction temperature. When the type and
amount of the vinyl bond formation-controlling agent (such as a tertiary
amine or an ether compound) are not changed during the polymerization
reaction, the amount of the vinyl bonds formed in the resultant copolymer
is influenced only by the polymerization reaction temperature. Therefore,
in this case, when the polymerization reaction is conducted at a constant
polymerization reaction temperature, the vinyl bonds are uniformly
distributed in the resultant copolymer. On the other hand, when the
polymerization is conducted while elevating the polymerization reaction
temperature, the resultant copolymer has a non-uniform distribution with
respect to the vinyl bonds, wherein a portion of the copolymer which is
formed at an early stage of the polymerization (where the polymerization
reaction temperature is low) has a high vinyl bond content and a portion
of the copolymer which is formed at a late stage of the polymerization
(where the polymerization reaction temperature is high) has a low vinyl
bond content. Therefore, in the present invention, it is recommended that
the change in the reaction temperature during the polymerization is
suppressed as much as possible, and that, more specifically, the
difference between the highest reaction temperature and the lowest
reaction temperature is 20.degree. C. or less, preferably 15.degree. C. or
less, more preferably 10.degree. C. or less.
The copolymer prior to the hydrogenation (i.e., unhydrogenated copolymer)
can be produced, for example, by a living anionic polymerization conducted
in a hydrocarbon solvent using a polymerization initiator, such as an
organic alkali metal compound. Examples of hydrocarbon solvents include
aliphatic hydrocarbons, such as n-butane, isobutane, n-pentane, n-hexane,
n-heptane and n-octane; alicyclic hydrocarbons, such as cyclohexane.
cycloheptane and methylcycloheptane; and aromatic hydrocarbons, such as
benzene, toluene, xylene and ethylbenzene.
As the polymerization initiator, it is possible to use aliphatic
hydrocarbon-alkali metal compounds, aromatic hydrocarbon-alkali metal
compounds, organic amino-alkali metal compounds, which are generally known
to have a living anionic polymerization activity with respect to a
conjugated diene and a vinyl aromatic compound. Examples of alkali metals
include lithium, sodium and potassium. As preferred examples of organic
alkali metal compounds, there can be mentioned lithium compounds having at
least one lithium atom in a molecule of a C.sub.1 -C.sub.20 aliphatic or
aromatic hydrocarbons (such as a dilithium compound, a trilithium compound
and a tetralithium compound). Specific examples of lithium compounds
include n-propyllithium, n-butyllithium, sec-butyllithium,
tert-butyllithium, a reaction product of diisopropenylbenzene and
sec-butyllithium, and a reaction product obtained by reacting
divinylbenzene, sec-butyllithium and a small amount of 1,3-butadiene.
Further, it is also possible to use any of the organic alkali metal
compounds described in U.S. Pat. No. 5,708,092, GB Patent No. 2,241,239
and U.S. Pat. No. 5,527,753.
In the present invention, when the copolymerization of a conjugated diene
monomer and a vinyl aromatic monomer is performed in the presence of the
organic alkali metal compound as a polymerization initiator, it is
possible to use a tertiary amine compound or an ether compound as a vinyl
bond formation-controlling agent, which is used for controlling the amount
of vinyl bonds (i.e., a 1,2-vinyl bond and a 3,4-vinyl bond) formed by the
conjugated diene monomers, and for controlling the occurrence of a random
copolymerization of a conjugated diene and a vinyl aromatic compound. As
the tertiary amine compound, it is possible to use a compound represented
by the formula: R.sup.1 R.sup.2 R.sup.3 N, wherein each of R.sup.1,
R.sup.2 and R.sup.3 independently represents a C.sub.1 -C.sub.20
hydrocarbon group or a C.sub.1 -C.sub.20 hydrocarbon group substituted
with a tertiary amino group. Specific examples of tertiary amine compounds
include N,N-dimethylaniline, N-ethylpiperidine, N-methylpyrrolidine,
N,N,N',N'-tetramethylethylenediamine,
N,N,N',N'-tetramethylethylenediamine, 1,2-dipiperidinoethane,
trimethylaminoethylpiperazine, N,N,N',N",N"-pentamethylethylenetriamine
and N,N'-dioctyl-p-phenylenediamine.
As the above-mentioned ether compound, it is possible to use a linear ether
compound and a cyclic ether compound. Examples of linear ether compounds
include dimethyl ether; diethyl ether; diphenyl ether; ethylene glycol
dialkyl ethers, such as ethylene glycol dimethyl ether, ethylene glycol
diethyl ether and ethylene glycol dibutyl ether; and diethylene glycol
dialkyl ethers, such as diethylene glycol dimethyl ether, diethylene
glycol diethyl ether and diethylene glycol dibutyl ether. Examples of
cyclic ether compounds include tetrahydrofuran, dioxane,
2,5-dimethyloxolane, 2,2,5,5-tetramethyloxolane,
2,2-bis(2-oxolanyl)propane and an alkyl ether of a furfuryl alcohol.
In the present invention, the copolymerization of a conjugated diene
monomer and a vinyl aromatic monomer in the presence of the organic alkali
metal compound as a polymerization initiator can be conducted either in a
bacthwise manner or in a continuous manner. Further, the copolymerization
may be conducted in a manner wherein a batchwise operation and a
continuous operation are used in combination. For achieving a molecular
weight distribution suitable for improving the processability of the
hydrogenated copolymer, it is preferred to conduct the copolymerization in
a continuous manner. The reaction temperature for the copolymerization is
generally in the range of from 0 to 180.degree. C., preferably from 30 to
150.degree. C. The reaction time for the copolymerization varies depending
on other conditions, but is generally within 48 hours, preferably in the
range of from 0.1 to 10 hours. It is preferred that the atmosphere of the
copolymerization reaction system is an atmosphere of an inert gas, such as
nitrogen gas. With respect to the polymerization reaction pressure, there
is no particular limitation so long as the pressure is sufficient for
maintaining each of the monomers and the solvent in a liquid state.
Further, care must be taken to prevent the intrusion of impurities (such
as water, oxygen and carbon dioxide), which deactivate the catalyst and/or
the living polymer, into the polymerization reaction system.
In the production of the hydrogenated copolymer of the present invention,
after completion of the copolymerization reaction, a multifunctional
coupling agent may be added to the polymerization reaction mixture to
perform a coupling reaction. As a bifunctional coupling agent, any of the
conventional coupling agents can be used. Specific examples of
bifunctional coupling agents include dihalides, such as
dimethyldichlorosilane and dimethyldibromosilane; and acid esters, such as
methyl benzoate, ethyl benzoate, phenyl benzoate and a phthalic ester.
Also as a tri- or more-functional coupling agent, any of the conventional
coupling agents can be used. Specific examples of tri- or more-functional
coupling agents include tri- or more-valent polyols; multivalent epoxy
compounds, such as epoxydized soy bean oil and diglycidylbisphenol A;
polyhalogenated compounds, such as a halogenated silicon compound
represented by the formula: R.sub.4-n SiX.sub.n, wherein each R
independently represents a C.sub.1 -C.sub.20 hydrocarbon group, X
represents a halogen atom, and n represents an integer of 3 or 4, and a
halogenated tin compound represented by the formula: R.sub.4-n SnX.sub.n,
wherein each R independently represents a C.sub.1 -C.sub.20 hydrocarbon
group, X represents a halogen atom, and n represents an integer of 3 or 4.
Specific examples of the above-mentioned halogenated silicon compound
include methylsilyl trichloride, t-butylsilyl trichloride, silicon
tetrachloride and brominated products thereof. Specific examples of the
above-mentioned halogenated tin compound include methyltin trichloride,
t-butyltin trichloride and tin tetrachloride. Also, dimethyl carbonate or
diethyl carbonate can be used as a multifunctional coupling agent.
By hydrogenating the thus obtained copolymer (unhydrogenated copolymer) in
the presence of a hydrogenation catalyst, the hydrogenated copolymer of
the present invention can be produced. With respect to the hydrogenation
catalyst, there is no particular limitation, and any of the conventional
hydrogenation catalysts can be used. Examples of hydrogenation catalysts
include:
(1) a carried, heterogeneous hydrogenation catalyst comprising a carrier
(such as carbon, silica, alumina or diatomaceous earth) having carried
thereon a metal, such as Ni, Pt, Pd or Ru;
(2) the so-called Ziegler type hydrogenation catalyst which uses a
transition metal salt (such as an organic acid salt or acetylacetone salt
of a metal, such as Ni, Co, Fe or Cr) in combination with a reducing
agent, such as an organoaluminum; and
(3) a homogeneous hydrogenation catalyst, such as the so-called
oraganometal complex of an organometal compound containing a metal, such
as Ti, Ru, Rh or Zr.
Specific examples of hydrogenation catalysts include those which are
described in Examined Japanese Patent Publication Nos. Sho 42-8704 and Hei
1-37970. As preferred examples of hydrogenation catalysts, there can be
mentioned a titanocene compound and a mixture of a titanocene compound and
a reductive organometal compound.
Examples of titanocene compounds include those which are described in
Unexamined Japanese Patent Application Laid-Open Specification No. Hei
8-109219. As specific examples of titanocene compounds, there can be
mentioned compounds, each independently having at least one ligand (e.g.,
biscyclopentadienyltitanium dichloride and
monopentamethylcyclopentadienyltitanium trichloride) having a
(substituted) cyclopentadienyl skeleton, an indenyl skeleton or a
fluorenyl skeleton. Examples of reductive organometal compounds include
organic alkali metal compounds, such as an organolithium compound; an
organomagnesium compound; an organoaluminum compound; an organoboron
compound; and an organozinc compound.
The hydrogenation reaction for producing the hydrogenated copolymer of the
present invention is generally conducted at 0 to 200.degree. C.,
preferably 30 to 150.degree. C. The hydrogen pressure in the hydrogenation
reaction is generally in the range of from 0.1 to 15 MPa, preferably from
0.2 to 10 MPa, more preferably from 0.3 to 5 MPa. The hydrogenation
reaction time is generally in the range of from 3 minutes to 10 hours,
preferably from 10 minutes to 5 hours. The hydrogenation reaction may be
performed either in a batchwise manner or in a continuous manner. Further,
the hydrogenation reaction may be performed in a manner wherein a
batchwise operation and a continuous operation are used in combination.
By the hydrogenation reaction of the unhydrogenated copolymer, a solution
of a hydrogenated copolymer in a solvent used is obtained. From the
obtained solution, the hydrogenated copolymer is separated. If desired,
before the separation of the hydrogenated copolymer, a catalyst residue
may be separated from the solution. Examples of methods for separating the
hydrogenated copolymer from the solution include a method in which a polar
solvent (which is a poor solvent for the hydrogenated copolymer) is added
to the solution containing the hydrogenated copolymer, thereby
precipitating the hydrogenated copolymer, followed by recovery of the
hydrogenated copolymer; a method in which the solution containing the
hydrogenated copolymer is added to hot water, while stirring, followed by
removal of the solvent by steam stripping; and a method in which the
solution containing the hydrogenated copolymer is directly heated to
evaporate the solvent.
The hydrogenated copolymer of the present invention may further contain any
of the conventional stabilizers, such as phenol type stabilizers,
phosphorus type stabilizers, sulfur type stabilizers and amine type
stabilizers.
The hydrogenated copolymer of the present invention may be graft-modified
using an .alpha.,.beta.-unsaturated carboxylic acid or a derivative (such
as an anhydride, an ester or an amide) thereof. The thus obtained
graft-modified product can also be used in the below-described composition
of the present invention.
