PIPE CONTAINING POLYETHYLENE OF INCREASED RESISTANCE TO SLOW GROWTH OF CRACKS Russian patent published in 2011 - IPC F16L9/12 F16L47/00 C08L23/06 C08L23/04 C08L23/08 

FIELD: machine building.

SUBSTANCE: composition includes basic resin containing (A) first ethylene homo- or copolymer fraction and (b) second ethylene homo- or copolymer fraction. Also, fraction (A) has flow rate of melt MFR₂ within the range from 300 to 600 g/10 min and lower average molecular weight, than fraction (B). Basic resin has density within the range from 0.945 to 0.949 kg/cm³, flow rate of melt MFR₅ within the range from 0.2 to 0.4 g/10 min, contents of alpha-olefine co-monomer 2.0-6.0 wt % and index of reduction of viscosity at shear SRV (2.7/210) within the range from 66 to 90.

EFFECT: manufactured pipes and additional items for pipes have good balance of processability, impact resilience, modulus of elasticity, resistance to rapid growth of cracks and values of calculated stress.

15 cl, 1 tbl, 2 ex