Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-06-23
2002-10-08
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C324S319000, C324S322000, C526S172000, C526S160000
Reexamination Certificate
active
06462136
ABSTRACT:
This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/JP99/05734 which has an International filing date of Oct. 18, 1999, which designated the United States of America.
1. Technical Field
The present invention relates to an ethylene copolymer, uses thereof and a process for preparing an ethylene copolymer. The present invention also relates to a resin composition containing the ethylene copolymer and uses thereof.
2. Background Art
Ethylene copolymers such as ethylene/&agr;-olefin copolymers are used for, for example, hollow containers, pipes, films, foamed articles and rubbers. The ethylene copolymers are required to be excellent in extrusion properties and bubble stability in the inflation molding and to have such an excellent moldability (flowability) that they can be expanded in a high expansion ratio in the expansion molding. Moreover, in the use of the ethylene copolymers as resin modifiers, they are required to exhibit excellent effects of improving mechanical properties such as break strength and impact resistance of molded products.
On this account, some proposals to obtain ethylene copolymers having excellent moldability and capable of providing molded products having excellent mechanical properties have been made so far.
For example, a method of blending an ethylene copolymer of high molecular weight with low-density polyethylene produced by a high-pressure polymerization process can improve moldability, but there is a problem that the resulting molded product becomes rigid or turbid to cause bad feeling.
A method of irradiating-an ethylene copolymer with electron rays or adding thereto an organic peroxide to partially-crosslink the ethylene copolymer and thereby form long-chain branches can improve moldability, but there is a problem of production of a gel.
A method of widening the molecular weight of an ethylene copolymer can improve moldability such as film moldability, but the content of a low molecular weight component increases, and as a result, the mechanical properties are lowered, or the molded article has a sticky surface. For this reason, an attempt to blend an ethylene/&agr;-olefin copolymer having a narrow molecular weight distribution and a low molecular weight with an ethylene/&agr;-olefin copolymer having a high molecular weight has been made. However, an ethylene/&agr;-olefin copolymer having a high molecular weight and a high content of an &agr;-olefin, particularly an ethylene/&agr;-olefin copolymer having excellent impact resistance, a high content of an &agr;-olefin, a high molecular weight and rubber-like properties, has not been obtained by a process using a conventional catalyst such as a vanadium catalyst, a metallocene catalyst or a Ziegler-Natta catalyst. Accordingly, development of an ethylene/&agr;-olefin copolymer having a wide molecular weight distribution, excellent moldability, a high content of an &agr;-olefin and excellent impact resistance and a process for preparing the copolymer has been desired.
The present invention has been made under such circumstances as described above, and it is an object of the invention to provide an ethylene copolymer which is excellent in extrusion properties and bubble stability in the inflation molding, has such an excellent moldability that it can be expanded in a high expansion ratio in the expansion molding and is capable of producing a molded product having excellent mechanical properties such as high break strength and high impact resistance, and uses thereof. It is another object of the invention to provide a process for preparing the ethylene copolymer. It is a further object of the invention to provide a resin composition containing the ethylene copolymer and uses thereof.
DISCLOSURE OP THE INVENTION
The ethylene copolymer (a) according to the invention is obtained from ethylene and an &agr;-olefin of 3 to 20 carbon atoms and satisfies the following requirements (i) to (v):
(i) said copolymer comprises 90 to 99% by mol of recurring units derived from ethylene (sometimes referred to as “ethylene units” hereinafter) and 1 to 60% by mol of recurring units derived from an &agr;-olefin of 3 to 20 carbon atoms (sometimes referred to as “C
3-20
&agr;-olefin units” hereinafter),
(ii) the ratio (Mz/Mw) of a 2 average molecular weight (Mz) to a weight-average molecular weight (Mw), each molecular weight being measured by gel permeation chromatography, is in the range of 10 to 30, and said ratio (Mz/Mw) and the ratio (Mw/Mn) of a weight-average molecular weight (Mw) to a number-average molecular weight (Mn), each molecular weight being measured by gel permeation chromatography, satisfy the following relation
(Mz/Mw)>(Mw/Mn),
(iii) the intrinsic viscosity, as measured in decalin at 135° C., is in the range of 0.5 to 4 dl/g,
(iv) the ratio (&eegr;
0.01
/&eegr;*
8
) of a melt viscosity (&eegr;*
0.01
) at a shear rate of 0.01 rad/sec, as measured at 190° C., to a melt viscosity (n*
8
) at a shear rate of 8 rad/sec, as measured at 190° C., and the intrinsic viscosity (&eegr;) satisfy the following relation (1)
(&eegr;*
0.01
/&eegr;*
8
)≧0.843×(&eegr;)+1.0 (1),
and
(v) the absolute value of an activation energy (E
a
) of a shift factor of melt viscoelasticity is not more than 4×10
9
J/mol.K.
The ethylene copolymer (a) according to the invention is, for example, an ethylene copolymer comprising:
an ethylene/&agr;-olefin copolymer (b) which comprises 40 to 99% by mol of recurring units derived from ethylene and 1 to 60% by mol of recurring units derived from an &agr;-olefin of 3 to 20 carbon atoms and has a value of Mw/Mn, as measured by gel permeation chromatography (GPC), of 1.8 to 3.0 and an intrinsic viscosity of not less than 10 dl/q, and
an ethylene/&agr;-olefin copolymer (c) which comprises 40 to 99% by mol of recurring units derived from ethylene and 1 to 60% by mol of recurring units derived from an &agr;-olefin of 3 to 20 carbon atoms and has a value of Mw/Mn, as measured by GPC, of 1.5 to 3.0 and an intrinsic viscosity of 0.3 to 3 dl/g;
wherein the weight ratio ((b)/(c)) of the ethylene/&agr;-olefin copolymer (b) to the ethylene/&agr;-olefin copolymer (c) is in the range of 0.1/99.9 to 30/70.
The ethylene/&agr;-olefin copolymer (b) is obtained by, for example, copolymerizing ethylene and an &agr;-olefin of 3 to 20 carbon atoms in the presence of a transition metal imine catalyst comprising:
(A) a transition metal imine compound represented by the following formula (I), and
(B) at least one compound selected from the group consisting of:
(B-1) an organometallic compound,
(B-2) an organoaluminum oxy-compound, and
(B-3) a compound which reacts with the transition metal imine compound (A) to form an ion pair;
wherein M is a transition metal atom of Group 3 to Group 11 of the periodic table,
m is an integer of 1 to 6,
R
1
to R
6
may be the same or different, they are each a hydrogen atom, a halogen atom, a hydrocarbon group, a heterocyclic compound residual group, an oxygen-containing group, a nitrogen-containing group, a boron-containing group, a sulfur-containing group, a phosphorus-containing group, a silicon-containing group, a germanium-containing group or a tin-containing group, two or more of them may be bonded to each other to form a ring, and when m is 2 or greater, one group of R
1
to R
6
contained in one ligand and one group of R
1
to R
6
contained in another ligand may be bonded to each other, and R
1
s, R
2
s, R
3
s, R
4
s, R
5
s or R
6
s among the ligands may be the same or different,
n is a number satisfying a valence of M,
X is a hydrogen atom, a halogen atom, a hydrocarbon group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a boron-containing group, an aluminum-containing group, a phosphorus-containing group; a halogen-containing group, a heterocyclic compound residual group, a silicon-containing group, a germanium-containing group or a tin-containing group, and when n is 2 or greater, plural groups indicated by X may be the same or different and plural group
Fujita Terunori
Mitani Makoto
Morizono Kenichi
Okada Keiji
Saito Junji
Birch & Stewart Kolasch & Birch, LLP
Lu Caixia
Mitsui Chemicals Inc.
Wu David W.
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