| 摘要 |
The present invention is concerned with a polypropylene composition comprising a polypropylene base resin, the polypropylene composition having
- a XHU content of less than 1.25 wt.-%;
- a F30 melt strength of at least 30 cN, determined in the Rheotens test at 200°C; and
- a melt extensibility v30 of at least 200 m/s, determined in the Rheotens test at 200°C. In another aspect the present invention is concerned with a polypropylene composition having an MFR (2.16 kg, 230 °C, ISO 1133) of 1.0 to 5.0 g/10 min comprising a polypropylene base resin, the polypropylene base resin being obtainable by
producing an intermediate polypropylene having an MFR (2.16 kg, 230 °C, ISO 1133) of 0.5 to 2.5 g/10 min in the presence of an asymmetric catalyst;
mixing the intermediate polypropylene with peroxide and at least one diene at a temperature of 20 to 90 °C for at least 2 minutes to form a pre-mixed material;
melt mixing the pre-mixed material in a melt mixing device at a barrel temperature in the range of 180 to 300 °C, whereby the melt mixing device is a melt mixing device includes a feed zone, a kneading zone and a die zone, whereby an initial barrel temperature T1 is maintained in the feed zone, a barrel temperature T2 is maintained in the kneading zone and a die barrel temperature T3 is maintained in the die zone, whereby the barrel temperatures T1, T2, and T3 satisfy the following relation: T1 < T3 < T2. In yet another aspect the present invention is concerned with a process for the production of a polypropylene composition having
- a XHU content of less than 1.25 wt.-%;
- a F30 melt strength of at least 30 cN, determined in the Rheotens test at 200°C; and
- a meit extensibility v30 of at least 200 m/s, determined in the Rheotens test at 200°C
whereby an asymmetric catalyst derived intermediate polypropylene having an MFR (2.16 kg, 230 °C, ISO 1133) of 0.5 to 2.5 g/10 min is mixed with peroxide and at least one diene at a temperature of 20 to 90 °C for at least 2 minutes to form a pre-mixed material; and the pre-mixed material is melt mixed in a melt mixing device at a barrel temperature in the range of 180 to 300 °C. In yet another aspect the present invention is concerned with foam comprising the polypropylene composition according to the present invention. The present invention is further concerned with the use of the polypropylene composition for producing foamed articles. |
