Photochromic polyurethane laminate
A photochromic polyurethane laminate wherein the photochromic polyurethane layer of the laminate has been crosslinked with an isocyanate-active prepolymer using a crosslinking agent. The crosslinking agent is formulated to have at least three functional groups that are reactive with functional groups of the polyurethane or of the isocyanate-active prepolymer. A method of making the photochromic polyurethane laminate includes steps of causing the crosslinking.
1. A photochromic polyurethane laminate comprising:
a crosslinked photochromic polyurethane layer prepared from a composition comprising:
a polyurethane;
an isocyanate prepolymer;
a crosslinking agent comprising a (hydroxyalkyl)urea compound having one functional urea group and two functional hydroxyl groups; and
a photochromic agent;
a first resin layer attached to a first side of the crosslinked photochromic polyurethane layer; and
a second resin layer attached to a second side of the crosslinked photochromic polyurethane layer.
2. The photochromic polyurethane laminate according to claim 1 , wherein the polyurethane is formed from a polycaprolactone diol.
3. A photochromic polyurethane laminate comprising:
a first resin layer;
a second resin layer; and
a crosslinked photochromic polyurethane layer disposed between the first and the second resin layers, the crosslinked photochromic polyurethane layer formed of a composition comprising:
a polyurethane;
an isocyanate prepolymer;
a crosslinking agent having at least three functional groups that react with hydroxyl groups of the polyurethane and isocyanate groups of the isocyanate prepolymer; and
at least one photochromic compound.
4. The photochromic polyurethane laminate according to claim 3 , wherein the crosslinking agent having said at least three functional groups is a (hydroxyalkyl)urea compound comprising one functional urea group and at least two functional hydroxyl groups.
5. The photochromic polyurethane laminate according to claim 4 , wherein said one functional urea group of said (hydroxyalkyl)urea compound reacts with said hydroxyl groups of the polyurethane.
6. The photochromic polyurethane laminate according to claim 4 , wherein said at least two functional hydroxyl groups of said (hydroxyalkyl)urea compound reacts with said isocyanate groups of the isocyanate prepolymer.