Optical Film Having Reverse Wavelength Dispersion and Display Device Including the Same (As Amended)

Patent metadata

Field	Value
Publication number	US-2016200851-A1
Application number	US-201414911706-A
Country	US
Kind code	A1
Filing date	Aug 18, 2014
Priority date	Aug 19, 2013
Publication date	Jul 14, 2016
Grant date	—

Abstract

An optical film having reverse wavelength dispersion and a display device including the same are provided. The optical film according to the present invention has a thin thickness and excellent reverse wavelength dispersion, and thus it can be suitably applied to a λ/2 wave plate, a λ/4 wave plate, a protection film, and an anti-reflection film of a display device using liquid crystals or OLEDs.

First claim

1 . An optical film comprising a copolymer including a repeating unit derived from polymerization of 80 to 99.99% by weight of a compound represented by the following Chemical Formula 1 and 0.01 to 20% by weight of an acrylate-based compound and satisfying the following Equation I and Equation II:

wherein R 1 is hydrogen or a methyl group; and
R 2 is an aromatic hydrocarbon group having 5 to 20 carbon atoms or a heteroaromatic hydrocarbon group having 5 to 20 carbon atoms, and at least one hydrogen atom included in the aromatic hydrocarbon group and the heteroaromatic hydrocarbon group is substituted by a hydroxyl group, a carboxyl group, a halogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 5 to 12 carbon atoms, an arylalkyl group having 7 to 12 carbon atoms, or an acyl group having 2 to 4 carbon atoms;
[Equation I]
Δn (450 nm) /Δn (550 nm) <1.0

[Equation II]
Δn (650 nm) /Δn (550 nm) >1.0

wherein Δn(λ) means a specific birefringent index at the wavelength λ.

2 . The optical film of claim 1 , wherein the compound represented by Chemical Formula 1 is one or more compounds selected from the group consisting of N-vinylcarbazole, N-vinylindole, 1-vinylnaphthalene, 1-vinylanthracene, and N-vinylphthalimide.

3 . The optical film of claim 1 , wherein the acrylate-based compound is a compound represented by the following Chemical Formula 2:

wherein R 3 is hydrogen or a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms,
R 4 is a single bond, linear or branched alkylene having 1 to 20 carbon atoms, a linear or branched alkenylene having 2 to 20 carbon atoms, or a linear or branched alkynylene having 2 to 20 carbon atoms, and
R 5 is hydrogen, a carboxyl group, or an epoxy group.

4 . The optical film of claim 1 , wherein the copolymer has a weight average molecular weight (Mw) of 10,000 to 3,000,000.

5 . The optical film of claim 1 , wherein the copolymer has a glass transition temperature (Tg) of 100 to 300° C.

6 . A method of preparing the optical film of claim 1 , the method comprising the steps of:
preparing a copolymer including a repeating unit derived from polymerization of 80 to 99.99% by weight of a compound represented by the following Chemical Formula 1 and 0.01 to 20% by weight of an acrylate-based compound; forming a film including the copolymer; and drawing the film:

wherein R 1 is hydrogen or a methyl group; and
R 2 is an aromatic hydrocarbon group having 5 to 20 carbon atoms or a heteroaromatic hydrocarbon group having 5 to 20 carbon atoms, and at least one hydrogen atom included in the aromatic hydrocarbon group and the heteroaromatic hydrocarbon group is substituted by a hydroxyl group, a carboxyl group, a halogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryl group having 5 to 12 carbon atoms, an arylalkyl group having 7 to 12 carbon atoms, or an acyl group having 2 to 4 carbon atoms.

7 . The method of claim 6 , wherein the film including the copolymer is formed on a substrate film including a cellulose triacetate film, a polyethylene terephthalate film, a cyclo olefin polymer film, a polycarbonate film, or a polynorbornene film.

8 . A display device comprising the optical film of claim 1 .

Assignees

• Lg Chemical Ltd

Inventors

• Lee Sung Kyoung
• Choi Dai Seung
• Park Eun Seok
• Chun Sung-Ho

Classifications

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title

• C08J2339/04

  Homopolymers or copolymers of monomers containing heterocyclic rings having nitrogen as ring member · CPC title

• C08F226/12 Primary

  N-Vinylcarbazole · CPC title

• B29C55/00

  Shaping by stretching, e.g. drawing through a die; Apparatus therefor (B29C61/08 takes precedence) · CPC title

• C08F220/10

  Esters · CPC title