Production of polypropylene having improved properties
View Patent ↗A process for producing polypropylene having increased melt strength, the process comprising irradiating polypropylene which has been polymerised using a Ziegler-Natta catalyst with an electron beam having an energy of at least 5 MeV and a radiation dose of at least 10 kGray and mechanically processing the irradiated polypropylene to form long chain branches on the polypropylene molecules, whereby the polypropylene has a melt flow index (MFI) of at least 25 dg/min.
1. A process for producing a propylene polymer having increased melt strength, the process comprising irradiating a propylene polymer which has been polymerized using a Ziegler-Natta catalyst with an electron beam having an energy of at least 5 MeV and a radiation dose of at least 10 kGray and mechanically processing a melt of the irradiated propylene polymer to form long chain branches on the propylene polymer molecules, whereby the irradiated propylene polymer has a melt flow index (MFI) of at least 25 dg/min.
2. A process according to claim 1 wherein the electron beam has an energy of at least 10 MeV.
3. A process according to claim 1 wherein the electron beam has an energy within the range of 10–25 MeV.
4. A process according to claim 1 wherein the power of the electron beam is from 50 to 500 kW.
5. A process according to claim 1 wherein the power of the electron beam is from 120–250 kW.
6. A process according to claim 1 wherein the radiation dose is within the range of 10–60 kGray.
7. A process according to claim 1 wherein said propylene polymer is a polypropylene homopolymer.
8. A method of claim 1 wherein said pro;ylene polymer is a copolymer of propylene and at least one alpha olefin selected from a group consisting of ethylene and C 4 –C 10 1-olefins.
9. A process accorded to claim 1 wherein said propylene polymer is isotactic polypropylene.