PROTECTIVE POLYMER COATING Russian patent published in 2015 - IPC F16L13/02 B05D7/14 B29C41/20 B29C65/44 C09D123/06 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of joining pipes with a polymer coating, which includes steps of obtaining pipe segments with a polymer coating but without coating at both ends; steps of welding the pipe segments with a polymer coating; applying a curable polymer (A) on the uncoated area of the welded pipe segments to obtain a first coating layer; and applying a polymer composition (B) on the first coating layer to obtain a top coating layer with thickness of 0.5-10 mm, wherein the polymer composition (B) has a melt flow rate MFR2 in the range of 1.0-6.0 g/10 min, measured according to ISO 1133 at temperature 190°C and a 2.16 kg load, and includes, as the basic component, a polymer consisting of (B-1) non-elastomeric polyethylene in amount of 60-85 wt % of the total weight of the composition, which is obtained using a catalyst with a single polymerisation centre, and (B-2) an elastomer which includes a copolymer of ethylene and at least one polar comonomer, wherein component (B-1) or components (B-1) and (B-2) are grafted using an acid grafting agent. The invention also relates to the use of the composition (B) as a top coating layer with thickness of 0.5-10 mm, which is used to coat a steel pipe in the welded joint area, as well as to a method of coating a steel pipe and using the polymer composition (B) to coat the welded joint area of a steel pipe or steel pipes themselves.

EFFECT: coating has strong surface adhesion and has good mechanical properties.

17 cl, 1 tbl