Photochromic polyurethane laminate
View Patent ↗A photochromic polyurethane laminate wherein the photochromic polyurethane layer of the laminate has been crosslinked with a 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 method of making a photochromic polyurethane laminate comprising:
providing a polyurethane;
preparing a solution from said polyurethane;
adding an isocyanate prepolymer into said solution;
introducing di(trimethylolpropane) as a crosslinking agent into said solution;
introducing at least one photochromic dye into said solution;
forming a crosslinked photochromic polyurethane layer from said solution;
placing said crosslinked photochromic polyurethane layer between a first and a second resin sheet to form a multilayer laminate; and
curing said laminate.
2. A method according to claim 1 wherein said step of forming a crosslinked photochromic polyurethane layer from said solution comprises reacting at least three functional groups of said crosslinking agent with functional isocyanate groups of said isocyanate prepolymer.
3. A method according to claim 1 , wherein said step of forming a crosslinked photochromic polyurethane layer from said solution comprises reacting at least three functional groups of said crosslinking agent with functional hydroxyl groups of said polyurethane.
4. A method according to claim 1 , wherein the step of providing a polyurethane comprises providing a thermoplastic polyurethane.
5. A method according to claim 1 , wherein the step of providing a polyurethane comprises providing a polyurethane formed from polyester polyols.
6. A method according to claim 1 , wherein the step of adding an isocyanate prepolymer comprises providing an isocyanate prepolymer formed from an aliphatic diisocyanate.
7. A method according to claim 1 , further comprising placing said crosslinked photochromic polyurethane layer between a first polycarbonate sheet and a second polycarbonate sheet.
8. A method according to claim 1 , wherein the step of forming a crosslinked photochromic polyurethane layer from said solution comprises casting said solution on a surface of a substrate to form a film.
9. A method of making a photochromic polyurethane laminate comprising:
forming a polyurethane by reaction of a prepolymer with a chain extender;
preparing a solution of said polyurethane;
adding an isocyanate prepolymer to said solution;
adding di(trimethylolpropane) as a crosslinking agent to said solution;
adding at least one photochromic dye into said solution;
forming a crosslinked photochromic polyurethane layer from said solution;
interposing said crosslinked photochromic polyurethane layer between a first and a second resin layer to form a multilayer laminate; and
curing said laminate.
10. A method according to claim 9 , wherein said step of forming a crosslinked photochromic polyurethane layer from said solution comprises reacting at least three functional groups of said crosslinking agent with functional isocyanate groups of said isocyanate prepolymer.
11. A method according to claim 9 , wherein said step of forming a crosslinked photochromic polyurethane layer from said solution comprises reacting at least three functional groups of said crosslinking agent with functional hydroxyl groups of said polyurethane.
12. A method according to claim 9 , wherein the step of forming a polyurethane by reaction of a prepolymer with a chain extender comprises forming said polyurethane from a mixture comprising a polyester polyol.
13. A method according to claim 9 , wherein the step of interposing said crosslinked photochromic polyurethane layer between a first and second resin layer to form a multilayer laminate comprises interposing said crosslinked photochromic polyurethane layer between a first polycarbonate sheet and a second polycarbonate sheet.
14. A method according to claim 9 , wherein the step of forming a crosslinked photochromic polyurethane layer from said solution comprises casting said solution on a surface of a substrate to form a film.