The present invention is directed to impact copolymers having an excellent combination of mechanical and optical properties, a method for their manufacture, an article comprising the inventive polymers and the use of the inventive polymers.

Conventional heterophasic polypropylene polymers are based on a matrix phase and a partly amorphous, partly crystalline C3/C2phase. Heterophasic polymers can be formed using heterogeneous Ziegler Natta catalysis and such polymers typically comprise a crystalline PE phase as well as the matrix phase and partially amorphous phase. In contrast, single-site catalyst produced heterophasic copolymers have a matrix phase and largely amorphous EPR phase. These polymers however, suffer from a number of design problems.

One problem is the dispersion of the elastomeric component in the matrix, due in part to the particle size of the elastomeric phase. Problems can also arise due to the viscosity ratio between elastomeric component and matrix (PP) phase, and the compatibility between these two phases. Incompatibility is a result of the compositional differences between the materials. Good compatibility could, in principle, be achieved at high propylene (C3) content (and hence low ethylene (C2) content) in the rubber phase which, however, leads to a higher glass transition temperature (Tg), again limiting the performance at very low temperatures, such as below −10° C.

EP 2 891 667 describes heterophasic polypropylenes having a high ethylene content in the rubber which, in turn, leads to improved mechanical properties. However, the optical properties as well as the brittle-to-ductile transition temperature can still be improved.

It has been surprisingly found that an improved balance of mechanical and optical properties can be achieved by using a rubber having a comparably low ethylene content.

