Process for preparing polyolefins

Details Process for preparing polyolefins Process for preparing polyolefins

2001-04-27

2002-11-26

Wilson, D. R. (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S124600

Reexamination Certificate

active

06486275

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a process for preparing novel polyolefins. More particularly, the present invention is concerned with a process for preparing polyolefins of good particles having a large average particle diameter and a narrow molecular weight distribution, which process is capable of greatly increasing the polymer yield per solid and that per transition metal, thereby permitting the omission of the step of removing catalyst remaining in the resulting polymer, further capable of increasing the bulk density of the polymer and decreasing a fine particulate portion of the polymer.
Heretofore, in this technical field there have been known many catalysts comprising inorganic magnesium solids as carriers such as magnesium halide, magnesium oxide and magnesium hydroxide and a transition metal compound such as a titanium compound or a vanadium compound supported on the carriers. However, the polyolefins obtained in the prior art are generally low in bulk density, relatively small in average particle diameter and generally wide in particle size distribution so contain a large proportion of fine particles. Besides, when these powdery polymers are subjected to forming, there arise problems such as dusting and lowering of the forming, efficiency. For the reason, improvement has keenly been desired from the standpoint of productivity and polymer handling. Further, still further improvements are considered necessary in order to satisfy the recent keen desire for omitting the pelletizing step and using a powdery polymer directly in a processing machine.
The present inventors have previously found out a novel catalyst component with the above drawbacks remedied and already filed patent applications thereon (see Japanese Patent Publication Nos. 11651/1989 and 12289/1989 and Japanese Patent Laid Open Nos. 149605/1985, 32105/1987 and 207306/1987). The use of this catalyst component can afford a polymer having a high bulk density and a large average particle diameter. However, a further improvement has been considered necessary for omitting the pelletizing step and using a powdery polymer directly in a processing machine.
The present inventors have also proposed a catalyst capable of affording a polymer having a narrow molecular weight distribution and a reduced proportion of low molecular weight components, which is required particularly in the film field (see Japanese Patent Application No. 200348/1989). However, this polymer still cannot be considered satisfactory.
Having made extensive studies for the purpose of remedying such drawbacks and obtaining in an extremely high activity a polymer having a high bulk density, a narrow particle size distribution, an extremely small proportion of fine particles and a narrow molecular weight distribution, the present inventors accomplished the present invention.
SUMMARY OF THE INVENTION
More specifically, the present invention resides in a process for preparing a polyolefin by polymerizing or copolymerizing an olefin or olefins in the presence of a catalyst comprising a solid catalyst component and an organometallic compound, the solid catalyst component being prepared by the reaction of the following components [I], [II] and [III]:
[I] a reaction product obtained by the following components (1), (2) and (3) in the presence of a compound represented by the general formula R
2
OH wherein R
2
is a hydrocarbon radical having 1 to 20 carbon atoms or an organic residue containing such an element as oxygen, nitrogen, sulfur, or chlorine:
(1) a silicon oxide and/or an aluminum oxide;
(2) a reaction product obtained by reacting a magnesium halide and a compound represented by the general formula [Me(OR)
n
X
z-n
] wherein Me represents an element of Groups I to IV in the Periodic Table, z represents the valence of the element Me, n is 0<n≦z, X is a halogen atom, and R is a hydrocarbon residue having 1 to 20 carbon atoms; and
(3) a titanium compound represented by the general formula Ti(OR
1
)
m
X
4-m
wherein R
1
is a hydrocarbon radical having 1 to 20 carbon atoms, X is a halogen atom, and m is 0≦m≦4;
[II] an organoaluminum compound represented by the general formula Al(OR
3
)
p
R
4
q
X
3-(p+q)
wherein R
3
and R
4
, which may be the same or different, are each a hydrocarbon residue having 1 to 24 carbon atoms, X is a halogen atom or hydrogen atom, and p and q are 0≦p<3, and 0≦q≦3, provided 0<p+q≦3; and
[III] a silicon compound represented by the general formula [R
5
a
R
6
b
R
7
c
Si(OR
8
)
d
X
4-(a+b+c+d)
] where R
5
, R
6
, R
7
and R
8
, which may be the same or different, are each a hydrocarbon residue having 1 to 20 carbon atoms, X is a halogen atom, and a, b, c and d are 0≦a<4, 0≦b<4, 0≦c<4 and 0<d≦4, provided 0<a+b+c+d≦4.
By the process of the present invention there is obtained, in extremely high activity, a polyolefin having a relatively large average particle diameter, a narrow particle size distribution, a reduced proportion of fine particles and a narrow molecular weight distribution. Besides, the bulk density and free fluidity of the polyolefin are high. These characteristics are very advantageous to the polymerization operation.
Further, the polyolefin prepared by the process of the present invention can be subjected to forming not only as pellets but also in the form of powder, without causing any trouble.
It is also a characteristic feature of the present invention that the polymer obtained using the catalyst specified in the present invention is extremely narrow in its molecular weight distribution and small in the amount thereof extracted in hexane, and that the amount of low grade polymers by-produced is very small. Therefore, when film is formed using the polyolefin of a narrow molecular weight distribution prepared by the process of the present invention, it has a lot of merits, for example, high strength and transparency, superior anti-blocking property and heat-sealability.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described concretely hereinunder.
The catalyst used in the polyolefin preparing process of the present invention comprises a solid catalyst component and an organometallic compound, the said solid catalyst component being prepared from the following components [I], [II] and [III]:
[I] a reaction product obtained by the following components (1), (2) and (3) in the presence of a compound represented by the general formula R
2
OH wherein R
2
is a hydrocarbon radical having 1 to 20 carbon atoms or an organic residue containing such an element as oxygen, nitrogen, sulfur, or chlorine:
(1) a silicon oxide and/or an aluminum oxide;
(2) a reaction product obtained by reacting a magnesium halide and a compound represented by the general formula [Me(OR)
n
X
z-n
] wherein Me represents an element of Groups I to IV in the Periodic Table, z represents the valence of the element Me, n is 0<n≦z, X is a halogen atom, and R is a hydrocarbon residue having 1 to 20 carbon atoms; and
(3) a titanium compound represented by the general formula Ti(OR
1
)
m
X
4-m
wherein R
1
is a hydrocarbon radical having 1 to 20 carbon atoms, X is a halogen atom, and m is 0≦m≦4;
[II] an organoaluminum compound represented by the general formula Al(OR
3
)
p
R
4
q
X
3-(p+q)
wherein R
3
and R
4
, which may be the same or different, are each a hydrocarbon residue having 1 to 24 carbon atoms, X is a halogen atom or hydrogen atom, and p and q are 0≦p<3, and 0≦q≦3, provided 0<p+q≦3; and
[III] a silicon compound represented by the general formula [R
5
a
R
6
b
R
7
c
Si(OR
8
)
d
X
4-(a+b+c+d)
] where R
5
, R
6
, R
7
and R
8
, which may be the same or different, are each a hydrocarbon residue having 1 to 20 carbon atoms, X is a halogen atom, and a, b, c and d are 0≦a<4, 0≦b<4, 0

Affiliated with

Also associated with

Rating

Process for preparing polyolefins does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for preparing polyolefins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for preparing polyolefins will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2957428