Solvent-free-adhesive polyisocyanate composition, solvent-free adhesive, and method for producing multilayer film using the same

A method for producing a solvent-free adhesive, the solvent-free adhesive comprising a solvent-free-adhesive polyisocyanate composition and a polyol (Y), the method comprising:

• preparing a solvent-free-adhesive polyisocyanate composition comprising a polyisocyanate (A) and an aromatic vinyl-maleic anhydride copolymer (B);
• and
• mixing the solvent-free-adhesive polyisocyanate composition with the polyol (Y) component,
• wherein the polyisocyanate (A) is a reaction product of a polyol component and a polyisocyanate comprising one or more selected from the group consisting of 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, toluene diisocyanate, m-xylene diisocyanate, carbodiimide-modified 4,4′-methylenebisphenyl diisocyanate, hexamethylene diisocyanate allophanate, isophorone diisocyanate, hexanemethylene diisocyanurate, and isocyanurate of isophorone diisocyanate,
• the polyol (Y) is a polyester polyol,
• the copolymer is of an aromatic vinyl and a maleic anhydride, and the copolymer has a molar ratio [aromatic vinyl/maleic anhydride] of raw material monomers of 2/1 to 3/1,
• the aromatic vinyl-maleic anhydride copolymer (B) is a styrene-maleic anhydride copolymer, and
• the solvent-free adhesive polyisocyanate composition is essentially free of propylene carbonate.