Polyethylene pipe resins

Pressure pipe resin comprising from 90 to 99.9 wt %, based on the total weight of the resin, of a polyethylene comprising from 35 to 60 wt % of a high molecular weight fraction having a density of up to 0.930 g/cm3 and from 40 to 65 wt % of a low molecular weight fraction having a density of at least 0.965 g/cm3, and from 0.1 to 10 wt %, based on the total weight of the resin, of an ionomer, which resin has an extrapolated 20° C./50 years stress at a 97.5% confidence level of at least 10 MPa (PE 100) according to ISO 9080.