An LDPE-based pelleted calcium carbonate (CaCO_3) concentrate was used to add 30wt.percnet fine-ground, surface-treated mineral to a 5.0 MI, 0.923rho autoclave-process LDPE homopolymer. This dry blend was extrusion coated onto flame-treated clay-coated board. Conventional aqueous-based polyethylenimine (PEI) primer coating of the board was used as the control. The combined flame pretreating of the board plus the addition of 30wt.percent CaCO_)3 to the LDPE coating resin yielded fiber-tear adhesion equivalent to that achieved with primer coating. This adhesion was achieved without major changes in extrusion conditions or web neck in. Calcium carbonate addition allowed polymer melt temperature to be reduced to as low as 570 deg F before loss in fiber-tear adhesion.
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