Method of forming dual-cure nanostructure transfer film
A method of forming a transfer film is described. The transfer film includes a template layer having a first major surface and an opposing second major surface. The second major surface includes a structured non-planar release surface. A backfill layer is disposed upon and conforms to the non-planar structured surface. The backfill layer includes a first cross-linked polymer and a plurality of multifunctional monomers, which cure via different and independent curing mechanisms.
1. A method of forming a transfer film comprising:
coating a backfill composition onto a structured non-planar template layer to form a backfill layer conforming to the structured non-planar template layer, the backfill composition comprising:
multifunctional epoxy monomers; and
from 40 wt-% to 90 wt-% multifunctional acrylate monomers, each multifunctional acrylate monomer having multiple acrylate functionalities; and
selectively curing the multifunctional epoxy monomers without curing the multifunctional acrylate monomers to form a transfer film from the backfill layer, the transfer film comprising a cross-linked epoxy polymer with the multifunctional acrylate monomers dispersed therein, wherein the transfer film adheres to the structured non-planar template layer, and wherein the transfer film has a glass transition temperature value that is less than 30 degrees centigrade.
2. The method according to claim 1 , further comprising applying a release liner onto a planar major surface of the transfer film wherein the transfer film is between the release liner and the structured non-planar template layer.
3. The method according to claim 1 , wherein the backfill composition additionally comprises a compatibilizer molecule having acrylate and epoxy functionalities.
4. The method according to claim 1 , wherein the transfer film has a glass transition temperature value that is less than 25 degrees centigrade.
5. The method according to claim 1 , wherein the cross-linked epoxy polymer comprises cycloaliphatic multifunctional epoxy groups.
6. The method according to claim 1 , wherein the multifunctional acrylate monomers comprise cycloaliphatic multifunctional acrylate groups.
7. The method according to claim 1 , wherein the curing step comprises cationic curing of the multifunctional epoxy monomers to form the cross-linked epoxy polymer without curing the multifunctional acrylate monomers.
8. The method according to claim 1 , wherein the curing step comprises thermally initiated cationic curing of the multifunctional epoxy monomers to form the cross-linked epoxy polymer without curing the multifunctional acrylate monomers.
9. The method according to claim 1 , wherein the curing step comprises photo-initiated cationic curing of the multifunctional epoxy monomers to form the cross-linked epoxy polymer without curing the multifunctional acrylate monomers.
10. A method comprising:
forming a transfer film according to the method of claim 1 ;
laminating the transfer film onto a receptor substrate; and
curing the multifunctional acrylate monomers to form a cross-linked acrylate polymer interpenetrating the cross-linked epoxy polymer defining a fully cured light transmission layer from the transfer film.
11. The method according to claim 10 , wherein the cross-linked epoxy polymer is cured via a cationic mechanism and the multifunctional acrylate monomers is cured via a free-radical mechanism.
12. The method according to claim 10 , further comprising removing the structured non-planar template layer from the fully cured light transmission layer.
13. The method according to claim 12 , wherein the fully cured light transmission layer has a haze value of less than 2% and a visible light transmission greater than 85% and a decomposition temperature greater than 250 degrees centigrade.
14. The method according to claim 10 , wherein the curing the multifunctional acrylate monomers step comprises thermally initiated free-radical curing of the multifunctional acrylate monomers to form the cross-linked acrylate polymer interpenetrating the cross-linked epoxy polymer.
15. The method according to claim 10 , wherein the curing the multifunctional acrylate monomers step comprises photo-initiated free-radical curing of the multifunctional acrylate monomers to form the cross-linked acrylate polymer interpenetrating the cross-linked epoxy polymer.