Reboundable optical structure
View Patent ↗A reboundable optical structure includes a base layer; and an optical element layer formed with a reboundable polymeric material and attached to the base layer. The optical structure can include a diffuser, fresnel lens, linear prism film, collimating film, lenticular elements, and retroreflective structures. A method for forming a reboundable optical structure includes providing a base layer; and attaching an optical element layer formed with a reboundable polymeric material and attached to the base layer, thereby forming an optical structure.
1. A reboundable optical structure comprising:
a) a base layer; and
b) an optical element layer attached to the base layer, said optical element layer having a microstructured surface resistant to scratches and abrasions by substantially recovering its original configuration and functionality over a period of minutes or hours, and wherein the optical element layer comprises from about 50% to about 90% by weight of a multi-functional terminally unsaturated urethane oligomer, wherein said urethane oligomer is the reaction product of (i) a terminally unsaturated isocyanate-containing polyurethane oligomer with (ii) an alkoxylated polyhydric alcohol;
(iii) from about 1% to about 25% by weight of a modifying monomer selected from one or more di-trimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate and their alkoxylated analogs; and
(iv) from about 0% to about 50% by weight of a reactive diluent.
2. The reboundable optical structure of claim 1 wherein said optical structure is selected from a group consisting of a diffuser, Fresnel lens, linear prism film, retroreflective elements, lenticular elements, and collimating film.
3. The reboundable optical structure of claim 1 wherein said base layer includes a polymer selected from a polyester, polycarbonate, polyacrylate and polyolefin or combination thereof.
4. The reboundable optical structure of claim 1 , wherein said optical element layer includes a diluent selected from a group consisting of monomers that include tetrahydrofurfuryl (meth)acrylate; 2-phenoxyethyl (meth)acrylate; isobornyl (meth)acrylate; 1,6-hexanediol di(meth)acrylate and their alkoxylated analogs.
5. The reboundable optical structure of claim 1 , wherein said optical element layer includes acrylates and methacylates.
6. The reboundable optical structure of claim 1 , wherein said optical element layer has a thickness in the range of between about 0.15 and about 150 micrometers.
7. The reboundable optical structure of claim 1 further including an adhesive coating located between the base layer and the optical element layer.
8. The reboundable optical structure of claim 1 , wherein the optical element layer further comprises a photoinitiator.
9. The reboundable optical structure of claim 1 , wherein the optical element layer further comprises a hindered amine light stabilizer.
10. The reboundable optical structure of claim 1 , wherein the optical element layer further comprises an ultraviolet absorber.
11. The reboundable optical structure of claim 1 , wherein the terminally unsaturated isocyanate-containing polyurethane oligomer is the product of reacting a polyisocyanate with a polyol and a hydroxyl-functional compound having an unsaturated group.
12. The reboundable optical structure of claim 11 , wherein the polyisocyanate is a diisocyanate.
13. The reboundable optical structure of claim 12 , wherein the diisocyanate is 3-isocyanatomethyl-3,5,5-trimethyl cyclohexylisocyanate (IPDI), hexamethylene diisocyanate (HDI), or methylene bis(cyclohexyl isocyanate).
14. The reboundable optical structure of claim 1 , wherein the weight % of the modifying monomer is from about 3% to about 10%.