Heat-crosslinked polyurethane adhesives, a polyurethane adhesive film and preparation method therefor

A heat-crosslinked polyurethane adhesive comprising the following components:

• 100 weight parts of a first waterborne resin;
• 8 to 12 weight parts of a first waterborne curing agent;
• 8 to 12 weight parts of a second waterborne resin;
• 4 to 10 weight parts of a second waterborne curing agent;
• 0.04 to 0.1 weight parts of a catalyst;
• 1 to 0.2 weight parts of a water-borne defoaming agent;
• wherein the first water-borne resin is a water-borne polyurethane dispersion, the first water-borne curing agent is a physically blocked isocyanate curing agent, the second water-borne resin is a hydroxy polyurethane dispersion, the second water-borne curing agent is a chemically blocked isocyanate curing agent;
• wherein the heat-crosslinked polyurethane adhesive further comprises a water-based thickener for adjusting its viscosity to 1000-5000 cps;
• the first water-borne resin is a sulfonic anionic water-borne polyurethane dispersion with a thermal activation temperature of 50-70° C., the second water-borne resin is a hydroxy polyurethane dispersion which contains between 1.6 and 2.0% hydroxyl groups by weight of its solid composition;
• the first water-borne curing agent is a microcapsulated isocyanate curing agent, which is a microcapsule dispersion formed by dispersing TDI and amine aqueous solution in an emulsifier under action of microcapsule catalyst.