POLYETHYLENE PIPE RESIN WITH HIGH RESISTANCE TO SLOW CRACK GROWTH

摘要

The present invention relates to a polyethylene composition comprising a base resin which comprises (A) a first ethylene homo- or copolymer fraction, and (B) a second ethylene-hexene-1 copolymer fraction, wherein fraction (A) has a lower molecular weight than fraction (B) and wherein fraction (B) is present in an amount of from 51.0 to 58.5 wt.%, preferably 52.0 to 57.5 wt.%, more preferably 53.0 to 57.0 wt.% based on the total weight of the base resin, wherein fraction (B) of the base resin has a content of units derived from hexene- 1 from 0.80 to 1.45 mol%, preferably of from 0.82 to 1.35 mol% and more preferably of from 0.85 to 1.30 mol%, wherein the base resin has a number average molecular weight Mn of 8,500 g/mol or higher, and wherein the polyethylene composition has a melt flow rate MFRs from 0.10 to 0.30 g/10min, preferably from 0.15 to 0.28, and still more preferably from 0.16 to 0.25 g/10min, to a process for producing the polyethylene composition, to an article, especially a pipe comprising the polyethylene composition and to the use of the polyethylene composition for the production of an article, especially a pipe.