Thermoplastic polyolefins with high flowability and excellent surface quality produced by a multistage process

Abstract

Reactor grade thermoplastic polyolefins with high flowability and excellent surface quality comprising (A) 40-90 wt % of a propylene homo- or copolymer matrix with an MFR in accordance with ISO 1 133 (230° C., 2.16 kg load) of >200 g/10 min and (B) 2-30 wt % of an elastomeric ethylene-propylene copolymer having an intrinsic viscosity IV (according to ISO 1628 with decalin as solvent) of ≦2.8 dl/g and an ethylene content of >50 to 80 wt % and (C) 8-30 wt % of an elastomeric ethylene-propylene copolymer having an intrinsic viscosity IV (according to ISO 1628 with decalin as solvent) of 3.0-6.5 dl/g and an propylene content of 50 to 80 wt %, the reactor grade thermoplastic polyolefins being obtainable by a multistage polymerization process with at least 3 polymerization steps 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) an organometallic cocatalyst and (iii) external donor represented by formula (I) Si(OCH 2 CH 3 ) 3 (NR 1 R 2 ) wherein R 1 and R 2 can be the same or different a represent a hydrocarbon group having 1 to 12 carbon atoms, as well as the use of these reactor grade thermoplastic polyolefins and molded articles produced from them.

1 . Reactor grade thermoplastic polyolefins with high flowability and excellent surface quality comprising
 (A) 40-90 wt % of a propylene homo- or copolymer matrix with an MFR in accordance with ISO 1133 (230° C., 2.16 kg load) of ≧200 g/10 min and   (B) 2-30 wt % of an elastomeric ethylene-propylene copolymer having an intrinsic viscosity IV (according to ISO 1628 with decalin as solvent) of ≦2.8 dl/g and an ethylene content of >50 to 80 wt % and   (C) 8-30 wt % of an elastomeric ethylene-propylene copolymer having an intrinsic viscosity IV (according to ISO 1628 with decalin as solvent) of 3.0-6.5 dl/g and a propylene content of 50 to 80 wt %,   
       the reactor grade thermoplastic polyolefins being obtainable by a multistage polymerization process with at least 3 polymerization steps 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) an organometallic cocatalyst and   (iii) external donor represented by the formula
   Si(OCH 2 CH 3 ) 3 (N x R y ) 
   
 
       wherein R x  and R y  can be the same or different and represent a hydrocarbon group having 1 to 12 carbon atoms. 
     
     
         2 . Reactor grade thermoplastic polyolefins according to  claim 1 , wherein the propylene matrix (A) is a propylene homopolymer. 
     
     
         3 . Reactor grade thermoplastic polyolefins according to  claim 1 , further comprising
 a) 5 to 15 wt % based on the weight of the polymer composition of an inorganic filler or   b) 1 to 15 wt % based on the weight of the polymer composition of an elastomer or   c) 0.05 to 3 wt % based on the weight of the polymer composition of alpha-nucleating agents   
       or mixtures therefrom. 
     
     
         4 . Reactor grade thermoplastic polyolefins according to  claim 1 , wherein the MFR (230° C., 2.16 kg load) according to ISO 1133 of the reactor grade thermoplastic polyolefin is above 20 g/10 min. 
     
     
         5 . A catalyst system for the production of reactor grade thermoplastic polyolefins in a multistage polymerization process with at least 3 polymerization steps, said catalyst system comprises
 (i) a Ziegler-Natta procatalyst which contains a trans-esterification product of a lower alcohol and a phthalic ester and   (ii) an organometallic cocatalyst and   (iii) external donor represented by the formula
   Si(OCH 2 CH 3 ) 3 (N x R y ) 
   
       wherein R x  and R y  can be the same or different a represent a hydrocarbon group having 1 to 12 carbon atoms, 
       said reactor grade thermoplastic polyolefins have high flowability and excellent surface quality and comprise
 (A) 40-90 wt % of a propylene homo- or copolymer matrix with an MFR 2  in accordance with ISO 1133 (230° C., 2.16 kg load) of 200 g/10 min and 
 (B) 2-30 wt % of an elastomeric ethylene-propylene copolymer having an intrinsic viscosity IV (according to ISO 1628 with decalin as solvent) of ≦2.8 dl/g and an ethylene content of >50 to 80 wt % and 
 (C) 8-30 wt % of an elastomeric ethylene-propylene copolymer having an intrinsic viscosity IV (according to ISO 1628 with decalin as solvent) of 3.0-6.5 dl/g and an propylene content of 50 to 80 wt %. 
 
     
     
         6 . The catalyst system according to  claim 5 , wherein the procatalyst (i) has been prepared by
 a) reacting a spray crystallized or emulsion solidified adduct of MgCl 2  and a C 1 -C 2  alcohol with TiCl 4      b) reacting the product of stage a) with a dialkylphthalate of formula (I)   
       
         
           
           
               
               
           
         
         
           wherein R 1 ′ and R 2 ′ are independently at least a C 5  alkyl 
           under conditions where a transesterification between said C 1  to C 2  alcohol and said dialkylphthalate of formula (I) takes place to form the internal donor 
         
         c) washing the product of stage b) or 
         d) optionally reacting the product of step c) with TiCl 4 . 
       
     
     
         7 . The catalyst system according to  claim 6 , wherein the dialkylphthalate of formula (I) is dioctylphthalate and that the C 1  to C 2  alcohol is ethanol. 
     
     
         8 . The catalyst system according to  claim 5 , wherein the Ziegler-Natta procatalyst (i) is used in the presence of an organometallic cocatalyst (ii) select from the group consisting of trialkylaluminium, dialkyl aluminium chloride and alkyl aluminium sesquichloride. 
     
     
         9 . The catalyst system according to  claim 8 , wherein the cocatalyst is triethylaluminium. 
     
     
         10 . The catalyst system according to  claim 5 , wherein the Ziegler-Natta procatalyst is used in the presence of diethylaminotriethoxysilane as external donor. 
     
     
         11 . Process for producing reactor grade thermoplastic polyolefins with high flowability and excellent surface quality, wherein the process is a multistage process with at least 3 polymerization steps in the presence of a catalyst system, said process comprises either a combination of one loop and two or three gas phase reactors or a combination of two loops and two gas phase reactors, said catalyst system comprises
 (i) a Ziegler-Natta procatalyst which contains a trans-esterification product of a lower alcohol and a phthalic ester and   (ii) an organometallic cocatalyst and   (iii) external donor represented by the formula
   Si(OCH 2 CH 3 ) 3 (NR x R y ) 
   wherein R x  and R y  can be the same or different a represent a hydrocarbon group having 1 to 12 carbon atoms,   and wherein further said reactor grad thermoplastic polyolefins comprises   (A) 40-90 wt % of a propylene homo- or copolymer matrix with an MFR in accordance with ISO 1133 (230° C., 2.16 kg load) of ≧200 g/10 min and   (B) 2-30 wt % of an elastomeric ethylene-propylene copolymer having an intrinsic viscosity IV (according to ISO 1628 with decalin as solvent) of ≦2.8 dl/g and an ethylene content of >50 to 80 wt % and   (C) 8-30 wt % of an elastomeric ethylene-propylene copolymer having an intrinsic viscosity IV (according to ISO 1628 with decalin as solvent) of 3.0-6.5 dl/g and a propylene content of 50 to 80 wt %.   
     
     
         12 . Process according to  claim 11 , comprising the steps of:
 producing a polypropylene polymer matrix (A) using the catalyst system in at least one slurry reactor   transferring the slurry reactor product into a gas phase reactor   producing a first ethylene/propylene-copolymer in the polymer matrix in the presence of the catalyst system in said first gas phase reactor   transferring the first gas phase reactor product into a 2 nd  gas phase reactor   producing a second ethylene/propylene-copolymer in the polymer matrix in the presence of the catalyst system in said 2 nd  GPR   recovering the polymer product for further processing,   
       said 1 st  and 2 nd  ethylene/propylene mixtures having different composition ratios, so that a bimodal rubber composition is obtained. 
     
     
         13 . Process according to  claim 11 , comprising the steps of:
 producing a polypropylene polymer matrix (A) using the catalyst system in at least one slurry reactor   transferring the slurry reactor product into a first gas phase reactor   wherein the slurry reactor product is further polymerized in the presence of the catalyst system in said first GPR   transferring the first GPR product into a 2 nd  GPR   producing a ethylene/propylene-copolymer in the polymer matrix in the presence of the catalyst system in said 2 nd  GPR   transferring the 2 nd  GPR product into a 3 rd  GPR and producing a second ethylene/propylene-copolymer in the polymer matrix in the presence of the catalyst system in said 3 rd  GPR and   recovering the polymer product for further processing,   
       said 1 st  and 2 nd  ethylene/propylene mixtures having different ethylene content and intrinsic viscosities, so that a bimodal rubber composition is obtained. 
     
     
         14 . The reactor grade thermoplastic polyolefins with high flowability and excellent surface quality according to  claim 1  used for the production of injection molded articles for automotive parts, wherein a product produced from said reactor wade thermoplastic polyolefins is an injection molded automotive part. 
     
     
         15 . Reactor grade thermoplastic polyolefins according to  claim 1  used in the production of molded articles, wherein a product produced from said reactor grade thermoplastic polyolefins is a molded article.