RU98116125A

RU98116125A - METHOD FOR PRODUCING COMPOSITION OF ETHYLENE POLYMERS

Info

Publication number: RU98116125A
Application number: RU98116125/04A
Authority: RU
Inventors: Промель Мишель; Моенс Брюно
Original assignee: Солвей Полиолефин Юроп-Бельджем
Priority date: 1997-08-20
Filing date: 1998-08-19
Publication date: 2000-05-20

Claims

1. A method of obtaining an ethylene polymer composition in at least two polymerization reactors connected in series, in which ethylene is polymerized in suspension in a first reactor in a medium comprising a diluent, hydrogen, a transition metal catalyst and cocatalyst to obtain 30 - 70 .% by weight relative to the total weight of the composition, of an ethylene homopolymer (a) with a flow index MI ₂ 5 - 1000 g / 10 min is recovered from said reactor the medium containing the homopolymer (a) and subjected to throttling at least a portion of orod, then the indicated at least partially degassed medium containing homopolymer (A), as well as ethylene and 1-hexene and possibly at least one other α-olefin, is introduced into the next reactor and the suspension is polymerized to obtain 30 - 70 wt.%, In relation to the total weight of the composition, a copolymer of ethylene and hexene (B) with a yield index MI _{5 of} 0.1 - 2 g / 10 min.

2. The method according to claim 1, characterized in that containing hexene in the copolymer (B) is not less than 0.4% and not more than 10 wt.%.

3. The method according to p. 1 or 2, characterized in that the copolymer (B) consists mainly of monomer units - derivatives of ethylene and 1-hexene.

4. The method according to one of claims 1 to 3, characterized in that the homopolymer (A) has MI _{2 of} not less than 50 and not more than 700 g / 10 min, and the copolymer (B) has MI _{5 of} not less than 0.015 and not more than 0 1 g / 10 min.

5. The method according to one of claims 1 to 4, characterized in that the diluent is isobutane.

6. The method according to one of claims 1 to 5, characterized in that the amount of hydrogen introduced into the first reactor is controlled so as to obtain a molar ratio of hydrogen to ethylene of 0.05 - 1 in the diluent.

7. The method according to one of claims 1 to 6, characterized in that the ratio of the concentration of hydrogen in the first reactor to the concentration of hydrogen in the next polymerization reactor is at least 20.

8. The method according to one of claims 1 to 7, characterized in that the amount of 1-hexene introduced into the next polymerization reactor is such that in this reactor the hexene / ethylene molar ratio in the diluent is 0.05 - 3.

9. The method according to one of claims 1 to 8, characterized in that the catalyst contains 10 to 30 wt.% Transition metal, 0.5 to 20 wt.% Magnesium, 20 to 60 wt.% Halogen and 0.1 to 10 wt.% aluminum.

10. The composition of ethylene polymers containing 30 - 70 wt.%, Relative to the total weight of the composition, ethylene homopolymer (A) with a yield index MI ₂ 5 - 1000 g / 10 min and 30 - 70 wt.%, Relative to the total the weight of the composition, a copolymer of ethylene and hexene (B) with a yield index MI _{5 of} 0.01 - 2 g / 10 min, which was obtained by the method according to one of claims 1 to 8.

11. The composition according to p. 10, characterized in that it has an MI _{5 of} not less than 0.07 and not more than 10 g / 10 min and an HLMI / MI ₅ ratio of more than 10.

12. The composition according to p. 10 or 11, characterized in that it is used for the manufacture of films and hoses.

13. Hoses obtained by extruding the composition of claim 10 or 11.