Achieving LDPE Coating Adhesion to Clay-Coated Board Using Calcium Carbonate Addition, 1997 Polymers, Laminations & Coatings Conference Proceedings

LDPE-based pelleted calcium carbonate (CaCO 3 ) concentrates were used to add 0, 15, & 3Owt.% fine-ground, surface-treated mineral to a 5.0 MI, 0.923r autoclave-process LDPE homopolymer. These dry blends were extrusion coated onto flame-treated clay-coated board. Polymer melt temperature and coating air gap were varied to determine how the addition of CaCO 3 affected adhesion response to variation in these process conditions. The combined flame pretreating of the board plus the addition of 3Owt.% CaCO 3 to the LDPE coating resin yielded adhesion level which prevented coating removal without fiber tear. This adhesion was achieved without major changes in extrusion conditions or web neck in. Reductions of 35% in coating WVTR and 20% poly-to-metal COF were observed at 3Owt.% calcium carbonate addition. The economics of utilizing calcium carbonate concentrates make this technology attractive as a commercial method of promoting LDPE coating adhesion to clay-coated board reducing coating C.O.F., and WVTR.