Patent ID: 7112642

Claim:
A process for preparing propylene polymers comprising: 1) a content of isotactic pentads (mmmm), measured by NMR, higher than 97%; 2) a molecular weight distribution, expressed by {overscore (M)} w /{overscore (M)} n ratio, equal to or higher than 6; and 3) a value of {overscore (M)} z /{overscore (M)} w ratio equal to or lower than 5.5; said process comprising only one polymerisation stage conducted in presence of a Ziegler-Natta catalyst comprising: a solid catalyst component comprising Mg, Ti, at least one halogen, and at least two electron donor compounds, wherein said electron donor compounds comprise at least one non-extractable succinate and at least one extractable electron donor compound, wherein said non-extractable succinate is present in an amount from 15 to 50% by mol with respect to a total amount of said electron donor compounds, and said non-extractable succinate is selected from esters of succinic acids which are not extractable by more than 20% by mol; and wherein said extractable electron donor compound is extractable by more than 30% by mol with respect to a total amount of said electron donor compounds; an organo-metal compound; and an outside electron-donor, wherein said outside electron-donor is a highly stereoregulated electron donor compound.