Polyurethane synthesis
A method is disclosed for producing a polyurethane film including the steps of depositing a prepolymer composition, drying the prepolymer composition, and crosslinking the propolymer composition.
1. A composition for producing a polyurethane comprising:
a prepolymer comprising carboxyl groups; and
a solvent, wherein the prepolymer and solvent together have a viscosity in the range of from about 1,000 to about 50,000 Pa-s; and
a polyaziridine compound;
wherein the composition is free of isocyanates and the composition has an elongation greater than about 100% and less than about 150%.
2. The composition of claim 1 , having a solids content of at least 40%.
3. The composition of claim 1 , having a solids content of at least 50%.
4. The composition of claim 1 , wherein the carboxyl groups are end groups.
5. The composition of claim 1 , wherein the carboxyl groups are not end groups.
6. The composition of claim 1 , wherein the polyurethane is an aliphatic polyurethane.
7. The composition of claim 1 , wherein the prepolymer comprises a plurality of silane moieties.
8. A graphic film, comprising:
the composition of claim 1 that is dried and crosslinked;
an adhesive layer; and
an optional release liner.
9. The graphic film of claim 8 , further comprising:
pigment or colorant.
10. The graphic film of claim 8 , further comprising:
a plasticizer.
11. The graphic film of claim 8 , further comprising:
at least one additional film layer.
12. The graphic film of claim 11 ,
wherein the at least one additional film layer provides at least one property selected from the group consisting of antigraffiti, self-healing, coloring, and weathering durability.