Flexible polyolefin thermal insulation foam and use thereof, and a method for producing a flexible polyolefin thermal insulation foam

A flexible non-crosslinked polyolefin thermal insulation foam having a percentage of open cells of less than 10% based on the total cells in the foam, and which is obtain by extruding a mixture comprising:

• i) an ethylene/α-olefin block copolymer, which comprises blocks of:
• A) crystalline or semi-crystalline blocks comprising ethylene in an amount of higher than 95 weight %;
• and
• B) elastomeric blocks comprising ethylene in an amount of 95 weight % or less and a comonomer content of 5 weight % or higher;
• wherein the ethylene/α-olefin block copolymer comprises alternating blocks of crystalline blocks of linear medium-density polyethylene, wherein medium-density is defined by a density range of 0.926-0.940 g/cm3, and elastomeric blocks of ethylene/1-octene;
• ii) one or more random polymers with a density of between 0.880 g/cm3 and 0.960 g/cm3, selected from the group of a metallocene polyethylene and/or a polyethylene;
• and
• iii) a cell stabilizer;
• wherein the mixture comprises between 20 and 75 weight % of said ethylene/α-olefin block copolymer under i);
• in a process comprising the steps of
• a) melting said mixture in the melting zone(s) of the extruder adjusted to temperatures of 160 to 220° C., at a pressure increasing from 1 bar up to 400 bar,
• b) injecting said physical blowing agent at an injection temperature of 140 to 220° C. and an injection pressure of 30 to 300 bar,
• c) cooling the molten mixture in one or more cooling zones adjusted to temperatures of 85 to 115° C., and
• d) extruding the mixture through an extrusion nozzle adjusted to a temperature of 85 to 115° C. and a pressure sufficiently high to keep any gas present in the mixture dissolved in the mixture.