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Patent Searching and Data


Title:
MULTI-STAGE PROCESS FOR PRODUCING POLYETHENE
Document Type and Number:
WIPO Patent Application WO/2001/000690
Kind Code:
A2
Abstract:
The invention relates to a multi-stage process for producing ethene homo or copolymer, which multi-stage process comprises, in any order, at least a liquid-phase polymerisation step (a) and a gas-phase polymerisation step (b). The process is characterised in that the polymerisation is carried out in the presence of a chromium catalyst. According to an embodiment of the invention, the molar masses and/or melt flow rates of the ethene homo or copolymers produced in steps (a) and (b) are essentially identical.

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Inventors:
ALMQVIST VIDAR (NO)
FOLLESTAD ARILD (NO)
Application Number:
PCT/FI2000/000580
Publication Date:
January 04, 2001
Filing Date:
June 28, 2000
Export Citation:
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Assignee:
BOREALIS TECH OY (FI)
ALMQVIST VIDAR (NO)
FOLLESTAD ARILD (NO)
International Classes:
C08F10/02; C08F255/00; C08F255/02; C08F297/08; C08F210/16; (IPC1-7): C08F10/00
Domestic Patent References:
WO1997027225A11997-07-31
WO1992012182A11992-07-23
Foreign References:
EP0829495A11998-03-18
Attorney, Agent or Firm:
BERGGREN OY AB (P.O. Box 16 Helsinki, FI)
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Claims:
Claims
1. Multistage process for producing ethene homo or copolymer, which multi stage process comprises, in any order, at least a liquidphase polymerisation step (a) and a gasphase polymerisation step (b), characterised in that the polymerisation is carried out in the presence of a chromium catalyst.
2. A process according to claim 1, characterised in that the process comprises a liquidphase polymerisation step (a) and a subsequent gasphase polymerisation step (b).
3. A process according to claim 1, characterised in that ethene homo or copolymer is produced in said liquidphase polymerisation step (a), and ethene homo or copolymer having essentially identical molar mass and/or melt flow rate than the ethene homo or copolymer produced in step (a), is produced in said one or more gasphase polymerisation step (b).
4. A process according to claim 3, characterised in that the difference between the melt flow rates at a load of 21,6 kg of the polymers produced in step (a) and in step (b) is at most 100%, preferably at most 50% of the melt flow rate of the final product.
5. A process according to claim 1, characterised in that the density of the ethene homo or copolymer produced in step (a) is at least 10 kg/m3, more preferably at least 15 kg/m3, most preferably at least 20 kg/m3 lower or higher than the density of the ethene homo or copolymer produced in step (b).
6. A process according to claim 1, characterised in that the density of the ethene homo or copolymer produced in the polymerisation step (a) is higher than the density of the ethene homo or copolymer produced in the polymerisation step (b).
7. A process according to claim 1, characterised in that the density of the final product is 915965 kg/m3.
8. A process according to claim 1, characterised in that the melt flow rate at a load of 21.6 kg of the final product is 2.5200 g/10 min.
9. A process according to claim 1, characterised in that the ratio of the amount of polyethene produced in the polymerisation step (a) to the amount of the poly ethene produced in the polymerisation step (b) is 30/7070/30, preferably 40/60 60/40.
10. A process according to claim 1, characterised in that said chromium catalyst comprises 0.55.0 wt% of a chromium compound and a carrier.
11. A process according to claim 1, characterised in that the polymerisation step (a) is carried out in a loop reactor.
12. A process according to claim 11, characterised in that the polymerisation step (a) is carried out in a reaction medium which is preferably a nonpolar hydro carbon, more preferably selected from the group consisting of propane, ibutane, n butane, pentane, hexane, heptane and the mixture of at least two of them, most preferably said medium is propane.
13. A process according to claim 11, characterised in that polymerisation step (a) is carried out in supercritical conditions, whereby the polymerisation temperature and pressure are above the corresponding critical points of the reaction mixture formed by reaction medium, monomer, hydrogen and optional comonomer and the polymerisation temperature is lower than the melting point of the polymer formed.
14. A process according to claim 1, characterised in that the polymerisation step (b) is carried out in one or more fluidised bed reactors.
15. A process according to claim 1, characterised in that at least one comonomer is used in the polymerisation step (b).
16. A process according to claim 15, characterised in that said comonomer is selected from the group consisting of C3C12 aolefins and their mixtures.
17. A process according to claim 15, characterised in that the reaction temperature in the polymerisation step (b) is 75110 °C, preferably 85105 °C.
18. A process according to claim 15, characterised in that the reaction pressure in the polymerisation step (b) is 550 bar, preferably 1030 bar.
19. A process according to claim 1, characterised in that it comprises one or more liquidphase polymerisation steps (a) and one or more gasphase polymerisation steps (b).
20. Ethene homo or copolymer, characterised in that it has been prepared according to any of claims 119.
21. Ethene homo or copolymer, characterised in that it comprises at least two fractions, which fractions have essentially the same molar mass and/or melt flow rate and essentially different densities.
22. Ethene homo or copolymer according to claim 21, characterised in that the difference between the melt flow rates at a load of 21.6 kg of the first and second fractions is at most 100%, preferably at most 50% of the melt flow rate of the final product.
23. Ethene homo or copolymer according to claim 21, characterised in that the difference of density of the at least two fractions is at least 10 kg/m3, more prefer ably at least 15 kg/m3, most preferably at least 20 kg/m3.
24. Ethene homo or copolymer according to any of claims 2123, characterised in that it has been prepared in a multistage polymerisation process.
Description:
I rational application No. INTERNATIONAL SEARCH REPORT PCT/FI 00/00580 Box I Observations where certain claims were found unsearchable (Continuation of item 1 of first sheet) This International Search Report has not been established in respect of certain claims under Article 17 (2) (a) for the following reasons: 1. J Claims Nos. : because they relate to subject matter not required to be searched by this Authority, namely: 2. jj Claims Nos.: because they relate to parts of the International Application that do not comply with the prescribed requirements to such an extent that no meaningful International Search can be carried out, specifically: 3. F-I Claims Nos.: because they are dependent claims and are not drafted in accordance with the second and third sentences of Rule 6.4 (a). Box 11 Observations where unity of invention is lacking (Continuation of item 2 of first sheet) This International Searching Authority found multiple inventions in this international application, as follows : see additional sheet 1 As all required additional search fees were timely paid by the applicant, this International Search Report covers all searchable claims. 2. As a) t searchable claims could be searched without effort justifying an additional fee, this Authority did not invite payment of any additional fee. 3. i As only some of the required additional search fees were timely paid by the applicant, this International Search Report covers only those claims for which fees were paid, specifically claims Nos.: 4. No required additional search fees were timely paid by the applicant. Consequently, this International Search Report is restricted to the invention first mentioned in the claims; it is covered by claims Nos.: 1-20 Remark on Protest The additional search fees were accompanied by the applicant's protes. nô protest accompanied the payment of additional search fees. u FURTHER INFORMATION CONTINUED FROM PCT/ISA/210 This International Searching Authority found multiple (groups of) inventions in this international application, as follows: 1. Claims: 1-20 relate to a process and an ethylene homo-or copolymer prepared thereof 2. Claims : 21-24 relate to a ethylene homo-or copolymer. INTERNATIONAL SEARCH REPORT Inter ional Application No formation on patent family members PC2/FI OO/OiAi580 Patent document Publication Patent family Publication cited in search report date member (s) date WO 9727225 A 31-07-1997 NO 300220 B 28-04-1997 AU 1677597 A 20-08-1997 BR 9707179 A 23-03-1999 CN 1209814 A 03-03-1999 EP 0876406 A 11-11-1998 WO 9212182 A 23-07-1992 FI 906428 A 29-06-1992 AT 130316 T 15-12-1995 DE 69114696 D 21-12-1995 DE 69114696 T 11-04-1996 DE 517868 T 22-07-1993 DK 517868 T 18-03-1996 EP 0517868 A 16-12-1992 ES 2079844 T 16-01-1996 GR 3018786 T 30-04-1996 JP 2529923 B 04-09-1996 JP 5504786 T 22-07-1993 NO 179286 B 03-06-1996 US 5326835 A 05-07-1994 EP 0829495 A 18-03-1998 EP 0832905 A 01-04-1998 US 6063878 A 16-05-2000



 
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