Process for the Nucleation of Polypropylene Resins

A process for nucleating polypropylene resins comprising the steps:

• (a) mixing in the molten state a polyolefin composition comprising:
• (1) from 95 to 99.9 wt % of a polypropylene resin having a Polydispersity Index value P.I.(1);
• and
• (2) from 0.1 to 5 wt % of at least one propylene polymer having a Polydispersity Index value (P.I.(2)) of at least 15,
• wherein the P.I.(1) and P.I.(2) values fulfill the equation P.I.(2)−P.I.(1)≧10, thereby forming a molten blend;
• and
• (b) cooling the molten blend.

A nucleated polypropylene resin obtained from a process comprising:

• (a) mixing in the molten state a polyolefin composition comprising:
• (1) from 95 to 99.9 wt % of a polypropylene resin having a Polydispersity Index value P.I.(1) and a crystallization temperature Tc(1);
• and
• (2) from 0.1 to 5 wt % of at least one propylene polymer having a Polydispersity Index value (P.I.(2)) of at least 15,
• wherein the P.I.(1) and P.I.(2) values fulfill the equation P.I.(2)−P.I.(1)≧10, thereby forming a molten blend;
• and
• (b) cooling the molten blend, wherein the nucleated polypropylene resin comprises a crystallization temperature Tc(1)I which is at least 5° C. higher than the crystallization temperature Tc(1) of the polypropylene resin (1).

Articles comprising a nucleated polypropylene resin obtained from a process comprising:

• (a) mixing in the molten state a polyolefin composition comprising:
• (1) from 95 to 99.9 wt % of a polypropylene resin having a Polydispersity Index value P.I.(1) and a crystallization temperature Tc(1);
• and
• (2) from 0.1 to 5 wt % of at least one propylene polymer having a Polydispersity Index value (P.I.(2)) of at least 15,
• wherein the P.I.(1) and P.I.(2) values fulfill the equation P.I.(2)−P.I.(1)≧10, thereby forming a molten blend;
• and
• (b) cooling the molten blend, wherein the nucleated polypropylene resin comprises a crystallization temperature Tc(1)I which is at least 5° C. higher than the crystallization temperature Tc(1) of the polypropylene resin (1).

A polyolefin composition comprising:

• (1) 95-99.9 wt % of a polypropylene resin having a Polydispersity Index value P.I.(1), said resin being selected from
• (i) propylene homopolymers having a solubility in xylene lower than 10 wt %,
• (ii) propylene copolymers containing from 0.05 to 20 wt %, with respect to the weight of the copolymer, of alpha-olefin units having from 2 to 10 carbon atoms other than propylene, said propylene copolymers having solubility in xylene lower than 15 wt %,
• (iii) mixtures of propylene homopolymers of item (i) and propylene copolymers of item (ii), and
• (iv) heterophasic compositions comprising (1) a propylene polymer selected among propylene polymers of item (i), (ii) and (iii), and (2) up to about 40 wt %, with respect to the weight of the heterophasic composition, of an elastomeric propylene copolymer containing up to about 50 wt %, with respect to the elastomeric fraction, of at least one comonomer unit selected from alpha-olefins having from 2 to 10 carbon atoms other than propylene;
• and
• (2) 0.1-5 wt % of a propylene polymer having a Polydispersity Index value P.I.(2) of at least 15, said propylene polymer being selected from propylene homopolymers, propylene copolymers containing up to 5.0 wt %, with respect to the weight of the copolymer, of alpha-olefin units having from 2 to 8 carbon atoms other than propylene or mixtures thereof,
• wherein the P.I.(1) and P.I.(2) values fulfill the equation P.I.(2)−P.I.(1)≧10.