Extrusion coated article
An extrusion coated article and process to extrusion coat a substrate are disclosed. A blend of LDPE having a MI 2 greater than 5 dg/min and m-LLDPE having a MI 2 less than 5 dg/min and, by differential scanning calorimetry, at least two melting points is used. Suitable substrates include paper, cardboard, metallized film, and metal foil. The polyolefin layer has a thickness within the range of 2 to 12 microns. A good combination of drawdown, seal strength, and hot tack strength is obtained.
1 . An extrusion coated article comprising a substrate and a polyolefin layer coated on the substrate, wherein the polyolefin layer has a thickness within the range of 2 to 12 microns and comprises a blend comprising: (a) from 60 to 90 wt. % of a low density polyethylene (LDPE) having a MI 2 greater than 5 dg/min; and (b) from 10 to 40 wt. % of a single-site based linear low density polyethylene (m-LLDPE) having a MI 2 less than 5 dg/min and, by differential scanning calorimetry (DSC), at least two melting points.
2 . The article of claim 1 having a seal strength, measured according to ASTM D882/F88, greater than 3.0 lbs. when sealed at 110° C. and tested at room temperature.
3 . The article of claim 1 having a coat weight of less than 7 lbs./ream.
4 . The article of claim 1 having a hot tack strength at 110° C., as measured by ASTM F1921, of greater than 0.7 lbs.
5 . The article of claim 1 wherein the substrate is selected from the group consisting of paper, cardboard, metallized film, and metal foil.
6 . The article of claim 1 wherein the m-LLDPE is a copolymer of ethylene with a C 6 -C 12 α-olefin.
7 . The article of claim 1 wherein the m-LLDPE has a density from 0.910 to 0.925 g/cm 3 .
8 . A multilayer article comprising a substrate, an inner polymer layer, and an outer polyolefin layer wherein the inner and outer layers are coextruded on the substrate and wherein the outer polyolefin layer has a thickness within the range of 2 to 12 microns and comprises a blend comprising: (a) from 60 to 90 wt. % of a LDPE having a MI 2 greater than 5 dg/min; and (b) from 10 to 40 wt. % of a m-LLDPE having a MI 2 less than 5 dg/min and, by DSC, at least two melting points.
9 . A process which comprises extrusion coating a substrate with a molten polyolefin layer to produce the article of claim 1 .
10 . A process which comprises coextruding onto a substrate a coating comprising a molten inner polymer layer and a molten outer polyolefin layer to produce the multilayer article of claim 8 .