Large-pole polyolefin, a method for its production and a procatalyst containing a transesterification product of a lower alcohol and a phthalic acid ester

A procatalyst composition suitable for preparing polyolefins having a median pore diameter of at least 15 .mu.m, said composition being produced by a process which comprises:

• a) contacting and mixing together (i) a solid MgCl.sub.2 carrier selected from the group consisting of solid MgCl.sub.2 and MgCl.sub.2 impregnated on silica, (ii) a lower alcohol R.sub.1 OH wherein R.sub.1 is a C.sub.1 -C.sub.4 -alkyl group, (iii) a titanium compound, and (iv) a first alkyl ester of phthalic acid, wherein the alkyl moiety of said first alkyl ester of phthalic acid has at least 6 carbon atoms, to form a composition comprising a contacting product;
• b) heating said composition comprising contacting product to a temperature of between 130.degree. C. and 140.degree. C. to transesterify said lower alcohol and said first alkyl ester of phthalic acid and form a transesterification product comprising a second alkyl ester of phthalic acid, wherein the alkyl moiety of said second alkyl ester of phthalic acid is said C.sub.1 -C.sub.4 -alkyl group, R.sub.1 ;
• c) separating and washing said transesterification product;
• and
• d) recovering said transesterification product as said procatalyst composition.

A method for preparing polyolefins having a median pore diameter of at least 15 .mu.m, comprising:

• (A) a polymerizing step, comprising contacting olefins with a procatalyst composition, wherein said procatalyst composition has been prepared by a process comprising:
• (a) contacting and mixing together (i) a solid MgCl.sub.2 carrier selected from the group consisting of solid MgCl.sub.2 and MgCl.sub.2 impregnated on silica, a (ii) lower alcohol R.sub.1 OH wherein R.sub.1 is a C.sub.1 -C.sub.4 -alkyl group, (iii) and a titanium compound to form a composition comprising a first reaction product, and reacting said composition comprising a first reaction product with a first alkyl ester of phthalic acid, wherein the alkyl moiety of said first alkyl ester of phthalic acid has at least 6 carbon atoms, to form a composition comprising a contacting product;
• (b) heating said composition comprising contacting product to a temperature of between 130.degree. C. and 140.degree. C. thereby transesterifying said lower alcohol and said first alkyl ester of phthalic acid into a transesterification product comprising a second alkyl ester of phthalic acid, wherein the alkyl moiety of said second alkyl ester of phthalic acid is said C.sub.1 -C.sub.4 -alkyl group, R.sub.1 ;
• (c) separating and washing said transesterification product;
• and
• (d) recovering the washed transesterification product as said procatalyst composition;
• and
• (B) recovering the polyolefin prepared with said procatalyst composition.