HIGH-EFFICIENCY METHOD OF APPLYING COATING ON TUBE USING MULTIMODAL ETHYLENE COPOLYMER AND TUBES WITH COATING OBTAINED USING SAID METHOD Russian patent published in 2012 - IPC C09D123/06 C09D123/08 F16L58/10 

FIELD: chemistry.

SUBSTANCE: invention relates to tubes with a coating, having a high-mechanical strength layer of multimodal polyethylene. The tube has an inner surface, an outer surface layer (A) and a coating layer (B) covering said outer surface layer (A). The coating layer (B) contains a coating composition (B-2) which contains 80-100 wt % multimodal ethylene copolymer (B-1), having shear thinning index SHI_2.7/210 from 10 to 100, where SHI_2.7/210 is determined by shear frequency experiments in linear viscosity stress interval at frequencies from 0.05 to 300 rad/s according to ISO 6721-1 as a ratio of complex viscosity values η(2.7 kPa)/η(210 kPa), containing a multimodal ethylene copolymer (B-1), which is a copolymer of ethylene and one or more alpha-olefin comonomers, having 4-10 carbon atoms. The multimodal ethylene copolymer (B-1) also contains (B-1-1) 49-59 wt % low-molecular weight ethylene homopolymer component with respect to weight of the multimodal ethylene copolymer (B-1), wherein said component (B-1-1) has weight-average molecular weight from 5000 g/mol to 70000 g/mol and (B-1-2) from 51 to 41 wt % high-molecular weight ethylene copolymer component with respect to the weight of the multimodal ethylene copolymer (B-1), wherein said component (B-1-2) has weight-average molecular weight from 100000 g/mol to 700000 g/mol and the multimodal ethylene copolymer (B-1) has weight-average molecular weight from 70000 g/mol to 250000 g/mol and flow melt index MFR₂, determined according to ISO 1133 at 190°C under a 2.16 kg load, from 0.05 g/10 min to 5 g/10 min, flow melt index MFR₅, determined according to ISO 1133 at 190°C under a 5 kg load, from 0.5 g/10 min to 10 g/10 min, and density from 930 kg/m³ to 955 kg/m³; and ratio of weight-average molecular weight to number-average molecular weight Mw/Mn from 24 to 50. Said high-molecular weight ethylene copolymer component has weight-average molecular weight from 100000 g/mol to 700000 g/mol. The multimodal ethylene copolymer (B-1) has weight-average molecular weight from 70000 g/mol to 250000 g/mol and flow melt index MFR₂, determined according to ISO 1133 at 190°C under a 2.16 kg load, from 0.05 g/10 min to 5 g/10 min, flow melt index MFR₅, determined according to ISO 1133 at 190°C under a 5 kg load, from 0.5 g/10 min to 10 g/10 min, and density from 930 kg/m³ to 955 kg/m³, and ratio of weight-average molecular weight to number-average molecular weight Mw/Mn from 24 to 50.

EFFECT: coating can be applied on tubes with high output and cost-effectiveness; coating has good mechanical properties.

26 cl, 1 dwg, 2 tbl