High purity heterophasic propylene copolymers

Process for producing high purity heterophasic polypropylene copolymers comprising

• (A) 73 to 98 wt % of a propylene homo- or copolymer matrix with an MFR2 in accordance with ISO 1133 (230° C., 2.16 kg load) of 45 g/10 min and
• (B) 2 to 27 wt % of an elastomeric copolymer, comprising propylene in an amount of at least 50 wt % of component (B) and at least ethylene and/or one other C4 to C10 alpha olefin in an amount of up to 50 wt % of component (B),
• said process comprises the steps of:
• producing a polypropylene polymer matrix (A) using a catalyst system, comprising a Ziegler-Natta procatalyst (i) which contains a trans-esterification product of lower alcohol and a phthalic ester, an external donor (iii) represented by formula (I) Si(OCH2CH3)3(NR1R2) wherein R1 and R2 can be the same or different a represent a hydrocarbon group having 1 to 12 carbon atoms, and optionally an organometallic cocatalyst (ii) in a first slurry reactor and optionally in a second slurry reactor, both slurry reactors using the same polymerization conditions,
• transferring the slurry reactor product into a 1st GPR
• producing an ethylene/propylene-copolymer in the polymer matrix in the presence of the catalyst system in said 1st GPR
• optionally transferring the 1st GPR product into a 2nd GPR and producing a second ethylene/propylene-copolymer in the polymer matrix in the presence of the catalyst system in said 2nd GPR, said 1st and 2nd ethylene/propylene mixtures may have the same or different composition ratios and
• recovering the polymer product for further processing.

High purity heterophasic polypropylene copolymers having an MFR2 in accordance with ISO 1133 (230° C., 2.16 kg load) of above 35 g/10 min, said copolymers comprise

• (A) 73 to 98 wt % of a propylene homo- or copolymer matrix with an MFR2 in accordance with ISO 1133 (230° C., 2.16 kg load) of ≧45 g/10 min and
• (B) 2 to 27 wt % of an elastomeric copolymer, comprising propylene in an amount of at least 50 wt % of component (B) and at least ethylene and/or one other C4 to C10 alpha olefin in an amount of up to 50 wt % of component (B),
• the heterophasic polypropylene copolymers being obtainable by a multistage polymerization process in the presence of a catalyst system comprising
• (i) a Ziegler-Natta procatalyst which contains a trans-esterification product of a lower alcohol and a phthalic ester and
• (ii) optionally an organometallic cocatalyst and
• (iii) an external donor represented by formula (I)
• Si(OCH2CH3)3(NR1R2)
• wherein R1 and R2 can be the same or different a represent a hydrocarbon group having 1 to 12 carbon atoms.

Method for improving purity of heterophasic polypropylene copolymer resin articles, the method comprising providing an article moulded from a heterophasic polypropylene copolymer having an MFR2 in accordance with ISO 1133 (230° C., 2.16 kg load) of above 35 g/10 min, said copolymer comprising

• A 73 to 98 wt % of a propylene homo- or copolymer matrix with an MFR2 in accordance with ISO 1133 (230° C., 2.16 kg load) of ≧45 g/10 min and
• (B) 2 to 27 wt % of an elastomeric copolymer, comprising propylene in an amount of at least 50 wt % of component (B) and at least ethylene and/or one other C4 to C10 alpha olefin in an amount of up to 50 wt % of component (B),
• the heterophasic polypropylene copolymers being obtainable by a multistage polymerization process in the presence of a catalyst system comprising
• (i) a Ziegler-Natta procatalyst which contains a trans-esterification product of a lower alcohol and a phthalic ester and
• (ii) optionally an organometallic cocatalyst and
• (iii) an external donor represented by formula (I)
• Si(OCH2CH3)3(NR1R2)
• wherein R1 and R2 can be the same or different a represent a hydrocarbon group having 1 to 12 carbon atoms.

Articles produced from a heterophasic polypropylene copolymer, wherein said heterophasic polypropylene copolymer has an MFR2 in accordance with ISO 1133 (230° C., 2.16 kg load) of above 35 g/10 min, said copolymer comprising

• (A) 73 to 98 wt % of a propylene homo- or copolymer matrix with an MFR2 in accordance with ISO 1133 (230° C., 2.16 kg load) of 45 g/10 min and
• (B) 2 to 27 wt % of an elastomeric copolymer, comprising propylene in an amount of at least 50 wt % of component (B) and at least ethylene and/or one other C4 to C10 al ha olefin in an amount of up to 50 wt % of component (B),
• the heterophasic polypropylene copolymers being obtainable by a multistage polymerization process in the presence of a catalyst system comprising
• (iv) a Ziegler-Natta procatalyst which contains a trans-esterification product of a lower alcohol and a phthalic ester and
• (v) optionally an organometallic cocatalyst and
• (vi) an external donor represented by formula (I)
• Si(OCH2CH3)3(NR1R2)
• wherein R1 and R2 can be the same or different a represent a hydrocarbon group having 1 to 12 carbon atoms.