MULTILAYER OPTICAL FILM STRUCTURES HAVING IMPROVED PROPERTIES AND THE USE THEREOF

• US 20090310222A1
• Filed: 06/09/2009
• Published: 12/17/2009
• Est. Priority Date: 06/11/2008
• Status: Abandoned Application

• Current Assignee: Covestro Deutschland AG
• Original Assignee: Bayer Materialscience AG (Covestro AG)
• Inventors: Meyer, Klaus, Pudleiner, Heinz, Braun, Hans, Nickel, Joerg
• Application Number:
  US12/481,162
• Publication Number:
  US 20090310222A1
• Time in Patent Office: Days
• US Class Current: 359/599
• CPC Class Codes: B32B 2250/40 Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
• CPC Class Codes: B32B 2270/00 Resin or rubber layer containing a blend of at least two different polymers
• CPC Class Codes: B32B 2307/412 Transparent
• CPC Class Codes: B32B 2307/416 Reflective
• CPC Class Codes: B32B 2307/584 Scratch resistance
• CPC Class Codes: B32B 2457/202 LCD, i.e. liquid crystal displays
• CPC Class Codes: B32B 2551/00 Optical elements
• CPC Class Codes: B32B 27/08 of synthetic resin
• CPC Class Codes: B32B 27/18 characterised by the use of special additives
• CPC Class Codes: B32B 27/286 comprising polysulphones; polysulfides
• CPC Class Codes: B32B 27/302 comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
• CPC Class Codes: B32B 27/308 comprising acrylic (co)polymers
• CPC Class Codes: B32B 27/32 comprising polyolefins comprising vinyl (co)polymers or acrylic (co)polymers B32B27/30
• CPC Class Codes: B32B 27/36 comprising polyesters
• CPC Class Codes: B32B 27/365 comprising polycarbonates
• CPC Class Codes: B32B 7/022 Mechanical properties
• CPC Class Codes: G02B 5/02 Diffusing elements; Afocal elements
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects

Abstract

The present invention relates to an optical film structure having improved properties and comprising at least one prism film and/or diffuser film as well as a multilayer optical film, wherein the multilayer optical film has at least one top film having an outer layer directed towards the prism film and/or diffuser film and made from a plastics composition containing a transparent thermoplastic and at least one quaternary ammonium salt of a perfluoroalkylsulfonic acid as lubricant additive. According to the invention the outer layer has at least one coefficient of sliding friction of <0.30 relative to the prism film and/or diffuser film measured in accordance with ASTM D 1894-06, with a roughness R3z of >5 μm (R3z in accordance with ISO 4288). The invention also provides a backlight unit containing the improved film structure and the use of the optical film structure according to the invention for liquid crystal screens.

Claims

1. A film structure comprising at least one prism film and/or diffuser film and a multilayer optical film, wherein said multilayer optical film comprises at least one top film having an outer layer which is directed towards said at least one prism film and/or diffuser film and is prepared from a plastics composition comprising a transparent thermoplastic and at least one quaternary ammonium salt of a perfluoroalkylsulfonic acid as lubricant additive, wherein said outer layer has at least one coefficient of sliding friction of less than 0.30 relative to said at least one prism film and/or diffuser film measured in accordance with ASTM D 1894-06, with a roughness R3z of greater than 5 μ

m measured in accordance with ISO 4288.

2. The film structure of claim 1, wherein said at least one prism film has a prism structure oriented towards said multilayer optical film and the outer layer of said multilayer optical film has a coefficient of sliding friction of less than or equal to 0.25 parallel to said prism structure of said at least one prism film and a coefficient of sliding friction of less than or equal to 0.30 transversely to said prism structure of said at least one prism film, measured in each case in accordance with ASTM D 1894-06, with a roughness R3z of greater than 5 μ

m (R3z in accordance with ISO

     4288).

3. The film structure of claim 1, wherein said multilayer optical film comprises an optical base film comprising a multilayer consisting of naphthalene dicarboxylic acid and/or terephthalic acid polyester.

4. The film structure of claim 1, wherein said plastics composition contains from 96 to 99.89 weight % of a transparent thermoplastic and from 0.001 to 4.0 weight % of quaternary ammonium salts of perfluoroalkylsulfonic acids as lubricant additive, wherein the total weight % of these components equals 100 weight %.

5. The film structure of claim 1, wherein said transparent thermoplastic is selected from the group consisting of polyacrylates, polymethacrylates, cycloolefin copolymers, polysulfones, polystyrenes, poly-alpha-methyl styrenes, polyesters, polycarbonates, polycarbonate/polyester blends, polycarbonate/polycyclohexyl methanol cyclohexane dicarboxylate, and polycarbonate/PBT.

6. The film structure of claim 1, wherein one or more of said at least one quaternary ammonium salt of a perfluoroalkylsulfonic acid is of formula (I)

R—

SO₃NR′

R″

R′

″

R″

″

 

 

(I)

is used as the lubricant additive, wherein

R is perfluorinated cyclic or linear, branched or unbranched carbon chains having 1 to 30 carbon atoms;

R′

is unsubstituted or halogen-, hydroxy-, cycloalkyl-, or alkyl-substituted, cyclic or linear, branched or unbranched carbon chains having 1 to 30 carbon atoms; and

R″

, R′

″

, and R″

″

are, independent of each other, cyclic or linear, branched or unbranched carbon chains having 1 to 30 carbon atoms optionally substituted with halogen, hydroxy, cycloalkyl, or alkyl.

7. The film structure of claim 1, wherein said at least one quaternary ammonium salt of a perfluoroalkylsulfonic acid is selected from the group consisting of:

perfluorooctanesulfonic acid tetrapropylammonium salt,

perfluorobutanesulfonic acid tetrapropylammonium salt,

perfluorooctanesulfonic acid tetrabutylammonium salt,

perfluorobutanesulfonic acid tetrabutylammonium salt,

perfluorooctanesulfonic acid tetrapentylammonium salt,

perfluorobutanesulfonic acid tetrapentylammonium salt,

perfluorooctanesulfonic acid tetrahexylammonium salt,

perfluorobutanesulfonic acid tetrahexylammonium salt,

perfluorobutanesulfonic acid trimethyl neopentylammonium salt,

perfluorooctanesulfonic acid dimethyl diisopropylammonium salt,

perfluorooctanesulfonic acid trimethyl neopentylammonium salt,

perfluorobutanesulfonic acid dimethyl dineopentylammonium salt,

perfluorooctanesulfonic acid dimethyl dineopentylammonium salt,

N-methyl tripropylammonium perfluorobutyl sulfonate,

N-ethyl tripropylammonium perfluorobutyl sulfonate,

tetrapropylammonium perfluorobutyl sulfonate,

dimethyl diisopropylammonium perfluorobutyl sulfonate,

N-methyl tributylammonium perfluorooctyl sulfonate,

cyclohexyldiethylmethylammonium perfluorooctyl sulfonate, and

cyclohexyltrimethylammonium perfluorooctyl sulfonate.

8. The film structure of claim 1, wherein said at least one quaternary ammonium salt of a perfluoroalkylsulfonic acid is diisopropyl dimethylammonium perfluorobutyl sulfonate.

9. The film structure of claim 1, wherein said multilayer optical film has a thickness of from 50 μ

m to 1000 μ

m.

10. The film structure of claim 1, wherein said outer layer of said multilayer optical film has a thickness of from 1 μ

m to 150 μ

m.

11. The film structure of claim 1, wherein said top film comprises at least one coextruded layer in addition to said outer layer.

12. The film structure of claim 11, wherein said coextruded layer has a thickness of from 10 μ

m to 100 μ

m.

13. A backlight unit for a liquid crystal screen comprising the film structure of claim 1.

14. An optical film set for a flat screen comprising the film structure of claim 1.