A varnish having low viscosity and a cured product thereof having a high degree of cross-linking, exhibiting excellent low dielectric properties and mechanical properties at high temperature, and a low coefficient of linear thermal expansion are provided. A varnish comprising an olefin-aromatic vinyl compound-aromatic polyene copolymerized oligomer satisfying specific conditions, one or more selected from the following (a) to (c), and (d) a solvent: (a) a curing agent; (b) one or a plurality of resins selected from a hydrocarbon-based elastomer, a polyphenylene ether-based resin, an olefin-aromatic vinyl compound-aromatic polyene copolymer, and an aromatic polyene-based resin; and (c) a polar monomer; and a cured product of the varnish.

A film forming aqueous dispersion having utility as heat seal coatings for blister packaging applications comprises a blend of 10-90% by weight of one or more polyurethane dispersions; 90-10% by weight one or more compatible ethylenic copolymer dispersions/emulsions; an anti-blocking additive at 0.1-12 weight % of the total solids; and optional additives including wetting, defoaming, thickener, antifungal additives. The heat seal coating compositions provide enhanced and balanced properties such as a reduction of organic solvents, a tack free coating surface off the press, good press runnability, easy clean-up, antiblocking from ambient temperature to 50 C., heat-activation with no pot life at elevated temperatures, and, heat sealability to various plastic substrates including Virgin Poly(ethylene terephthalate) (PET), recycle PET (RPET), Amorphous PET (APET), PET-Glycol modified (PETG), PETG/APET/PETG (GAG) and Polyvinyl chloride (PVC).

A film forming aqueous dispersion having utility as heat seal coatings for blister packaging applications comprises a blend of 10-90% by weight of one or more polyurethane dispersions; 90-10% by weight one or more compatible ethylenic copolymer dispersions/emulsions; an anti-blocking additive at 0.1-12 weight % of the total solids; and optional additives including wetting, defoaming, thickener, antifungal additives. The heat seal coating compositions provide enhanced and balanced properties such as a reduction of organic solvents, a tack free coating surface off the press, good press runnability, easy clean-up, antiblocking from ambient temperature to 50 C., heat-activation with no pot life at elevated temperatures, and, heat sealability to various plastic substrates including Virgin Poly(ethylene terephthalate) (PET), recycle PET (RPET), Amorphous PET (APET), PET-Glycol modified (PETG), PETG/APET/PETG (GAG) and Polyvinyl chloride (PVC).