Copolymer, process for production thereof, and molded...

Details Copolymer, process for production thereof, and molded... Copolymer, process for production thereof, and molded...

1999-07-09

2001-02-13

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S347100, C526S161000, C526S943000, C502S152000

Reexamination Certificate

active

06187889

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a copolymer suitable for a stretch film and a wrap film in particular, a process for producing said copolymer, and a molded article of said copolymer.
2. Description of the Related Arts
In general, an elastic recoverability, transparency and mechanical strength found in a polyvinyl chloride are required for a copolymer to be used as a stretch film, a shrink film or a wrap film. However, the polyvinyl chloride comes in question concerning environmental pollution because of the possibility of generation of harmful substances in incineration. Various kind of polymers are presently considered as a replacement for the polyvinyl chloride, but it is a status quo that none of them being satisfactory from the viewpoints of viscoelastic properties and transparency has been obtained.
Since copolymerization of an &agr;-olefin represented by propylene with an alkenyl aromatic hydrocarbon represented by styrene was carried out using a Solvay type titanium trichloride catalyst, studies using various solid catalysts have been carried out. For example, polymerization processes which use a solid catalyst using titanium tetrachloride and an electron donor are disclosed in Japanese Patent Publication (Kokai) Nos. 60-26011 and 4-318006. However, in both of those processes, the polymerization activity is low and a homopolymer is formed as a by-product. Further, the obtained copolymer has a low amount of copolymerized styrene and possesses some crystallinity, and is not adequate from the viewpoints of elastic recoverability, flexibility and transparency.
Japanese Patent Publication (Kokai) No. 8-269134 discloses a process for producing a copolymer of propylene with styrene which has syndiotactic propylene sequences using a so-called homogeneous Ziegler-Natta catalyst which uses a specific transition metal compound and an organoaluminum compound. However, the copolymer obtained by the process, has also a low styrene content and a crystallinity, and is insufficient from the viewpoints of elastic recoverability, flexibility and transparency.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a novel copolymer of an &agr;-olefin with an alkenyl aromatic hydrocarbon having a transparency and excellent elastic recoverability and flexibility, and not containing a halogen which may be pointed out as a cause for environmental pollution. Another object of the present invention is to provide a process for producing said copolymer at high polymerization activity, and a molded article of said copolymer which is excellent in mechanical strength, flexibility and anti-scratch property, and further has a transparency and good elastic recoverability.
In order to attain the above-mentioned objects, the present inventors have intensively studied about a copolymer of an &agr;-olefin with an alkenyl aromatic hydrocarbon which is based on a production process using a transition metal compound represented by a metallocene as a catalyst component, and have completed the present invention.
The present invention relates to a copolymer of an &agr;-olefin with an alkenyl aromatic hydrocarbon wherein the copolymer has a structure in which tertiary carbon atoms are mutually separated by two successive methylene groups in the backbone of the copolymer; a process for producing said copolymer which comprises copolymerizing an &agr;-olefin with an alkenyl aromatic hydrocarbon in the presence of a catalyst using (A) and [(B) and/or (C)] described below; and a molded article of said copolymer.
(A): a transition metal complex represented by the following general formula [I]:
(wherein M
1
represents a transition metal atom of the Group IV of the Periodic Table of the Elements; A represents an atom of the Group XVI of the Periodic Table of the Elements; J represents an atom of the Group XIV of the Periodic Table of the Elements; Cp
1
represents a group having a cyclopentadiene type anion skeleton; X
1
, X
2
, R
1
, R
2
, R
3
, R
4
, R
5
and R
6
independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an aryl group, a substituted silyl group, an alkoxy group, an aralkyloxy group, an aryloxy group or a di-substituted amino group; and R
1
, R
2
, R
3
, R
4
, R
5
and R
6
may be optionally combined with each other to form a ring);
(B): one or more aluminum compounds selected from the following (B1) to (B3);
(B1) an organoaluminum compound represented by the general formula E
1
a
AlZ
3−a
,
(B2) a cyclic aluminoxane having a structure represented by the general formula {—Al(E
2
)—O—}
b
, and
(B3) a linear aluminoxane having a structure represented by the general formula E
3
{—Al(E
3
)—O—}
c
AlE
3
2
(wherein E
1
, E
2
and E
3
respectively represent a hydrocarbon group, all of E
1
, all of E
2
and all of E
3
may be the same or different; Z represents a hydrogen atom or a halogen atom, and all of Z may be the same or different; a represents a number satisfying the expression 0<a≦3; b represents an integer of 2 or more and c represents an integer of 1 or more); and
(C): a boron compound of any one of the following (C1) to (C3);
(C1) a boron compound represented by the general formula BQ
1
Q
2
Q
3
,
(C2) a boron compound represented by the general formula G
+
(BQ
1
Q
2
Q
3
Q
4
)
−
, and
(C3) a boron compound represented by the general formula (L-H)
+
(BQ
1
Q
2
Q
3
Q
4
)
−
(wherein B represents a boron atom in the trivalent valence state; Q
1
to Q
4
may be the same or different and respectively represent a halogen atom, a hydrocarbon group, a halogenated hydrocarbon group, a substituted silyl group, an alkoxy group or a di-substituted amino group; G
+
represents an inorganic or organic cation; L represents a neutral Lewis base; and (L-H)
+
represents a Brønsted acid).


REFERENCES:
patent: 5866659 (1999-02-01), Chung et al.
patent: 0416815A2 (1991-03-01), None
patent: 0842955A2 (1998-05-01), None
patent: 60-26011 (1985-02-01), None
patent: 4318006 (1992-11-01), None
patent: 08269134 (1996-10-01), None
patent: 8269134 (1996-10-01), None
patent: WO9809999A2 (1998-03-01), None
Wu, Qing et al.Macromol. Chem. Phys.vol. 199, pp. 1715-1720, (1998).

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