Microstructured film containing polysulfone polymer
The invention relates to a film comprising microstructures on at least one surface thereof, the film comprising a polysulfone polymer. Such a film exhibits improved heat stability, light recycling capability, and faithful replication.
1 . A film comprising polysulfone polymer-containing light redirecting microstructures on at least one surface thereof.
2 . (canceled)
3 . The film of claim 1 wherein the polysulfone is characterized by having a repeating group represented by Formula (I) below:
wherein each of R and R′ is H or an alkyl group such as methyl or ethyl or a phenyl group; and
each of R 1 through R 4 independently represents hydrogen or one or more independently selected ring substituent groups.
4 . The film of claim 3 wherein R and R′ are methyl groups and each of R 1 through R 4 represents hydrogen.
5 . The film of claim 1 wherein the polysulfone has a weight average molecular weight of less than 27,000.
6 . The film of claim 5 wherein the polysulfone has a weight average molecular weight of from 5,000 to 21,000.
7 . The film of claim 1 wherein the light redirecting microstructures comprise individual elements having a ridgeline.
8 . The film of claim 1 wherein the light redirecting microstructures are linear prismatic structures.
9 . The film of claim 1 comprising a base layer and a microstructured layer comprising microstructures on at least one surface thereof wherein only the microstructured layer comprises a polysulfone polymer.
10 . The film of claim 1 comprising a base layer and a light redirecting layer comprising light redirecting microstructures on at least one surface thereof wherein only the light redirecting layer comprises a polysulfone polymer.
11 . The film of claim 10 wherein the base layer comprises a polymer having a Tg greater than 120° C.
12 . The film of claim 1 further comprising addenda selected from the list comprising a tinting compound, release compound, UV absorber, plasticizer, optical brightener, nanometer sized inorganic materials and fire resistant materials.
13 . The film of claim 1 wherein the microstructures have a height between 5 and 100 micrometers.
14 . The film of claim 1 wherein the film comprises two layers wherein the first layer has a weight average molecular weight less than 21,000 and the second layer has a weight average molecular weight of greater than 35,000.
15 . A method of forming the film of claim 1 comprising continuously melt casting the polysulfone polymer onto a patterned heated roller and cooling the polysulfone polymer while the polysulfone polymer is in contact with the heated roller having a pattern corresponding to the negative of the desired pattern.
16 . The method of claim 15 wherein the polysulfone polymer has an average molecular weight less than 27,000.
17 . The method of claim 15 wherein said heated roller is heated to a temperature greater than 200° C.
18 . The method of claim 15 wherein the patterned heat roller contains individual elements.
19 . The method of claim 15 wherein the patterned heat roller comprises an outermost surface comprising chrome having a hardness greater than 80 Rockwell C.
20 . A back-lit display device comprising a light source and a polysulfone polymeric film according to claim 1 .
21 . The display of claim 20 wherein the display is a liquid crystal display wherein the polysulfone polymeric film is located between the light source and a polarizing film.
22 . A film comprising polysulfone polymer-containing microstructures on at least one surface thereof in which the weight average molecular weight of the polysulfone polymer is less than 27,000.
23 . The film of claim 1 wherein the microstructures are predominantly comprised of a polysulfone polymer.
24 . The film of claim 1 wherein the film is predominantly comprised of a polysulfone polymer.