Waterborne adhesives for reduced basis weight multilayer substrates and use thereof

A multilayer substrate package comprising:

• (a) a first substrate, which is a substantially flat, having a first and a second side;
• (b) a second substrate, which is a substantially flat, having a first and a second side;
• and
• (c) an adhesive composition, sandwiched between the first substrate and the second substrate, comprising (i) an emulsion-based polymer selected from the group consisting of vinyl acetate ethylene dispersion, polyvinyl acetate, polyvinyl acetate polyvinyl alcohol, dextrin stabilized polyvinyl acetate, polyvinyl acetate copolymers, vinyl acetate—ethylene copolymers, vinylacrylic, styrene acrylic, acrylic, styrene butyl rubber, polyurethane and mixtures thereof;
• (ii) a plurality of expandable microspheres, wherein the microspheres is present in the adhesive composition in a volume of about 10 V/V % to about 50 V/V %;
• wherein the adhesive composition is partially set, coalesced onto the first and the second substrates, and contains greater than 10% moisture content;
• and
• wherein the expandable microspheres in the adhesive composition expand upon exposure to heat and/or radiation and the adhesive composition fully sets upon exposure to heat and/or radiation.