| abstract |
An improved aqueous base coating for paper substrates to be vacuum metallized consists essentially of an aqueous emulsion containing a film-forming polymer prepared by emulsion copolymerizing an acrylate monomer having a Tg of -55° to -70°C (e.g., butyl or 2-ethylhexyl acrylate) with selected vinyl polymerizable monomers having aTg of about +50° to +110 °C (e.g. methyl methacrylate, isobutyl methacrylate, styrene, or vinyl toluene) to give a polymer having a theoretical Tg of above -10° to +45 °C. The polymerization is carried out in the presence of about 25-40 wt.% of a water-soluble colloid polymer having a Tg of + 14 to + 80 °C. The colloid polymer is the ammonium salt of an acid-containing polymer having a molecular weight of about 2000-10000 which consists essentially of about 10-40% acrylic and/or methacrylic acid and about 60-90% of selected vinyl polymerizable monomers other than the acid monomer (e.g. styrene, butyl (meth)acrylate, isobutyl (meth) acrylate, methyl methacrylate and/or ethylene). |