FIELD: polymers.
SUBSTANCE: present invention relates to a polyethylene-based adhesive composition for use as an adhesive layer in multilayer products. Adhesive composition characterized by adhesive strength to steel from 40 to 65 N/mm at 23°C, from 30 to 45 N/mm at 60°C, and from 10 to 25 N/mm at 80°C, containing in relation to the total mass of the composition the following components: A) from 59 to 82% wt. of linear low density polyethylene (LLDPE) having a density in the range of 0.915 to 0.925 g/cm3 and characterized by a branched hydrocarbon chain with side branches containing at least 4 carbon atoms; B) from 15 to 20% wt. of high-density polyethylene (HDPE) grafted with a functional monomer - maleic anhydride, having a density of not less than 0.960 g/cm3, characterized by a molecular weight distribution value of not less than 5.9 and weight average molecular weights in the range from 65,000 to 7,0000 g/mol; C) from 3 to 20% wt. elastomer, which is a copolymer of ethylene with α-olefins and/or copolymers of ethylene with esters of unsaturated carboxylic acids; D) optional additives - up to 100%, while LLDPE and HDPE are characterized by an MFR190/2.16 in the range from 0.8 to 1.2 g/10 min, and the ratios of MFR of polyethylenes: LLDPE and HDPE grafted with a functional monomer is close to or equal to 1. The composition is obtained by mixing and processing components into a homogeneous hot melt using mixing equipment and an extruder. The resulting adhesive composition has high values of adhesive strength, including at elevated temperatures. The invention also relates to the use of an adhesive composition based on polyethylene as an adhesive layer in multilayer coatings, in particular as a multilayer insulation of pipes intended for the construction of gas and oil pipelines.
EFFECT: improving the adhesive strength of the composition based on polyethylene, in particular, improving the adhesion strength to steel at 23°C to values from 41 to 62 N/mm, at 60°C to values from 20 to 45 N/mm, at 80°C to values from 15 to 25 N/mm, as well as in reducing the concentration of polyethylene used in the composition, grafted with a functional monomer, which is attractive in terms of economic indicators.
56 cl, 3 tbl, 30 ex
