Polyurethane hot-melt adhesive with reduced viscosity

United States Patent（美國專利）： 8865842

The invention relates to crosslinking polyurethane adhesives having good initial adhesive strength and low application viscosity, which additionally contain non-crosslinking polyesters. 

Abstract： A reactive melt adhesive containing 30 to 70% of at least one prepolymer having at least two isocyanate groups having a molecular weight below 6000 g/mol, manufactured from polyether polyols and/or polyester polyols reacted with a molar excess of diisocyanates, the prepolymer containing less than 1% monomeric diisocyanate; 30 to 70 wt % of a thermoplastic polyester having a number-average molecular weight (M.sub.N) below 6000 g/mol, which comprises fewer than 1.4 groups reactive with NCO; and up to 30 wt % additives from the group of the catalysts, resins, plasticizers, fillers, pigments, stabilizers, or adhesion promoters.