Multilayer Mono-Material Polyethylene (PE) Assembly And Its Use In Food Packaging

A multilayer mono-material PE assembly, comprising at least two layers:

• a first layer consisting of one film of high-density polyethylene (HDPE) having a density value equal to or higher than 0.935 g/cm3, and
• a second layer comprising at least one sublayer comprising a polyethylene (PE) blend, each PE blend comprising with respect to the total amount of each sublayer:
• from 5 to 85 wt % of polyethylene resin having a density value in the range from 0.914 to 0.930 g/cm3,
• at least 15 wt % of a polyethylene component selected from the group consisting of
• i) a very low-density polyethylene (VLDPE) and/or an ultra low-density polyethylene (ULDPE) and having a density value ≤0.912 g/cm3,
• ii) a polyethylene copolymer selected from the group consisting of polyolefin plastomer (POP), ethylene-vinyl acetate (EVA), ethylene acrylic acid (EAA), ethylene n-butyl acrylate (EBA), ethylene ethyl acrylate (EEA), ethylene 2-ethyl hexyl acrylate (EEHA) and ethylene-methacrylic acid (EMAA), wherein the ethylene monomer is higher than or equal to 75 wt % and
• iii) a mixture of i) and ii), and
• wherein the difference of the melting point (ΔTm) of the first layer with respect to the second layer is in the range from 5 to 80° C.

A process for preparing the multilayer mono-material PE assembly according to claim 17 comprising the steps of:

• a) providing a first layer consisting of one film of high-density polyethylene (HDPE) having a density value equal to or higher than 0.935 g/cm3;
• b) providing an extrusion group, said extrusion group comprising at least one extruder, a feed block, an extrusion flat die and a Chill roll-Nip roll unit;
• c) placing the first layer on the Chill roll-Nip roll unit;
• d) loading in the at least one extruder at least one polyethylene (PE) blend, said PE blend comprising
• from 5 to 85 wt % of polyethylene resin having a density value in the range from 0.914 to 0.930 g/cm3,
• at least 15 wt % of a polyethylene component selected from the group consisting of
• i) a very low-density polyethylene (VLDPE) and/or an ultra low-density polyethylene (ULDPE) and having a density value ≤0.912 g/cm3,
• ii) a polyethylene copolymer selected from the group consisting of polyolefin plastomer (POP), ethylene-vinyl acetate (EVA), ethylene acrylic acid (EAA), ethylene n-butyl acrylate (EBA), ethylene ethyl acrylate (EEA), ethylene 2-ethyl hexyl acrylate (EEHA) and ethylene-methacrylic acid (EMAA), wherein the ethylene monomer is higher than or equal to 75% wt and
• iii) a mixture of i) and ii), and
• wherein the difference of the melting point (ΔTm) of the first layer with respect to the second layer is in the range from 5 to 80° C., and
• optional additives;
• e) extruding the at least one PE blend on the first layer through the extrusion flat die of the extrusion group, thus obtaining a mono-material polyethylene multilayer having the second layer comprising at least one sublayer comprising at least one polyethylene blend (PE),
• f) quenching the mono-material polyethylene multilayer, thus obtaining the multilayer mono-material PE assembly,
• wherein the setting parameters of the extrusion group were:
• a line speed of about 50-250 m/min,
• at least one extrusion coating weight of about 5-50 g/m2,
• a temperature profile of the at least one extruder from 170° C. to 300° C. and
• the quenching step is a cooling step from 300° C. to 15° C.