STEEL PIPES WITH THE POLYOLEFIN COATING Russian patent published in 2006 - IPC B32B1/08 B32B15/08 B32B27/32 F16L9/12 C08F10/06 C08F297/08 C08K5/00 

FIELD: chemical industry; ferrous metallurgy; production of the steel pipes with the polyolefin coating.

SUBSTANCE: the invention is pertaining to the field of polymer chemistry, in particular, to production of the polyolefin coating with the high dynamic resistibility to breaking at the coating of the steel pipes during their breaking and operation. The steel pipes with the polyolefin coatings consist of the core - the steel pipe, the not obligatory present intermediate foamed plastic material and the polyolefin coating; At that the polyolefin coating consists of the propylene block copolymers with the nucleating agents of the crystallization in the β-form, containing from 90.0 up to 99.9 (in mass %) links of propylene and from 0.1 up to 10.0 (in mass %) links α-olefins with 2 or 4-18 atoms of carbon, with the melt indexes within the range from 0.1 up to 8 g/10 minutes at 230°C/2.16 kg, which have IRτ of the propylene homopolymer cluster > 0.98, the coefficient of elasticity of elongation ≥ 1100 MPa and Sharpie impact elasticity at -20°C in the case of usage of the tested samples notched ≥ 6 kJ/m², where the tested polyolefin pipe manufactured out of the propylene copolymer with the nucleating agents of the crystallization in the β-form has the critical pressure > 25 bar and the dynamic resistibility to breaking > 3.5 Mnm^-3/2. The invention also presents the method of production of the steel pipes with the polyolefin coating. The steel pipes with the polyolefin coating may be used for transportation in the coastal area of such products as the crude oil or gas, or in the systems of the district centralized heat supply.

EFFECT: the invention ensures, that the steel pipes with the polyolefin coating may be used for transportation in the coastal area of the crude oil or gas, or in the systems of the district centralized heat supply.

2 dwg, 3 ex, 3 cl