Production of polyolefins having improved properties
View Patent ↗A process for producing polypropylene having increased melt strength, the process comprising (i) homopolymerising polypropylene or copolymerising propylene with one or more comonomers selected from ethylene and C4 to C101-olefins to produce a polypropylene homopolymer or copolymer respectively having a double bond concentration of at least 0.1 per 10,000 carbon atoms, (11) irradiating the polypropylene with an electron beam having an energy of at least 5 MeV and at radiation dose of at least 5 kGray, and (iii) melting and mechanically processing the melt of polypropylene to form long chain branches on the polypropylene molecules.
1. A process for producing a propylene polymer having increased melt strength, the process comprising (i) homopolymerising polypropylene or copolymerizing propylene with at least one comonomer selected from the group consisting of ethylene and C 4 to C 10 1-olefin to produce a polypropylene homopolymer or copolymer respectively having a double bond concentration of at least 0.1 per 10,000 carbon atoms, (ii) irradiating the propylene polymer with an electron beam having an energy of at least 5 MeV and at a radiation dose of at least 5 kGray, and (iii) melting the propylene polymer and mechanically processing the melt of said propylene polymer to form long chain branches on the propylene polymer molecules.
2. A process according to claim 1 wherein the propylene polymer is polymerised using a single site catalyst.
3. A process according to claim 1 wherein the electron beam has an energy of at least 10 MeV.
4. A process according to claim 1 wherein the electron beam has an energy within the range of 10–25 MeV.
5. A process according to claim 1 wherein the power of the electron beam is from 50 to 500 kW.
6. A process according to claim 1 wherein the power of the electron beam is from 120 to 250 kW.
7. A process according to claim 1 wherein the radiation dose is at least 10 kGray.
8. A process according to claim 6 wherein the radiation dose is within the range of 10–60 kGray.
9. A process according to claim 6 wherein the radiation dose is within the range of 20–40 kGray.
10. A process for producing polypropylene having increased melt strength, the process comprising irradiating polypropylene which has been polymerised using a metallocene catalyst with an electron beam having an energy of at least 5 MeV and a radiation dose of at least 5 kGray and melting the polypropylene and mechanically processing the melt of the irradiated polypropylene to form long chain branches on the polypropylene molecules.
11. A process according to claim 10 wherein the electron beam has an energy of at least 10 MeV.
12. A process according to claim 10 wherein the power of the electron beam is from 50 to 500 kW.
13. A process according to claim 10 wherein the power of the electron beam is from 120 to 250 kW.
14. A process according to claim 10 wherein the radiation dose is at least 10 kGray.
15. A process according to claim 14 wherein the radiation dose is within the range of 10–60 kGray.
16. A process according to claim 15 wherein the radiation dose is within the range of 20–40 kGray.