Cellulose ester optical films

Patent metadata

Field	Value
Publication number	US-9796791-B2
Application number	US-201213409747-A
Country	US
Kind code	B2
Filing date	Mar 1, 2012
Priority date	Apr 13, 2011
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

Regioselectively substituted cellulose esters having a plurality of aryl-acyl substituents and a plurality of alkyl-acyl substituents are disclosed along with methods for making the same. Such cellulose esters may be suitable for use in optical films, such as optical films having certain Nz values, −A optical films, and/or +C optical films. Optical films prepared employing such cellulose esters have a variety of commercial applications, such as, for example, as compensation films in liquid crystal displays and/or waveplates in creating circular polarized light used in 3-D technology.

First claim

We claim:

1. A +C optical film comprising a regioselectively substituted cellulose ester, wherein said regioselectively substituted cellulose ester comprises a plurality of alkyl-acyl substituents and a plurality of aryl-acyl substituents,
wherein said regioselectively substituted cellulose ester has an aryl-acyl degree of substitution (“DS aryl ”) in the range of 1.45 to 1.60,
wherein said regioselectively substituted cellulose ester has an alkyl-acyl degree of substitution (“DS alkyl ”) of in the range of 1.20 to 1.35,
wherein said regioselectively substituted cellulose ester has a hydroxyl degree of substitution (“DS OH ”) in the range of 0.10 to 0.30,
wherein the regioselectivity of said regioselectively substituted cellulose ester is such that the sum of the aryl-acyl degrees of substitution at C2 and C3 (“C2DS aryl ” and “C3DS aryl ”) minus the aryl-acyl degree of substitution at C6 (“C6DS aryl ”) is at least 0.25,
wherein said +C optical film has an out-of-plane retardation (“R th ”) in the range of from +50 to +800 nm as measured at a spectral range from 370 to 1000 nm,
wherein said +C optical film has an in-plane retardation (“R e ”) in the range of from −15 to +15 nm as measured at a spectral range from 370 to 1000 nm,
wherein the DS aryl is greater than the DS alkyl ,
wherein said +C optical film has an average thickness in the range of from 40 to 120 μm, and
wherein said aryl-acyl substituents comprise benzoate and said alkyl-acyl substituents comprise propionate.

2. The +C optical film of claim 1 , wherein the regioselectivity of said regioselectively substituted cellulose ester is such that the sum of C2DS aryl and C3DS aryl minus the C6DS aryl is in the range of from 0.50 to 1.10.

3. The +C optical film of claim 1 , wherein said +C optical film has an Rth in the range from +549.5 to +800 nm as measured at a spectral range from 370 to 1000 nm.

4. A liquid crystalline display (“LCD”) comprising a compensation film, wherein said compensation film comprises said +C optical film of claim 1 .

5. The LCD of claim 4 , wherein said LCD operates in in-plane-switching (“IPS”) mode.

6. The LCD of claim 4 , wherein said compensation film comprises at least one additional optical film disposed adjacent to said +C optical film.

7. The LCD of claim 6 , wherein said additional optical film is a +A optical film.

Assignees

• Buchanan Charles Michael
• Donelson Michael Eugene
• Guzman-Morales Elizabeth
• Mackenzie Peter Borden
• Wang Bin
• Eastman Chem Co

Inventors

• Buchanan Charles Michael
• Donelson Michael Eugene
• Guzman-Morales Elizabeth
• Mackenzie Peter Borden
• Wang Bin

Classifications

• B32B2457/202

  LCD, i.e. liquid crystal displays · CPC title

• C08B3/06

  Cellulose acetate {, e.g. mono-acetate, di-acetate or tri-acetate} · CPC title

• G02B1/04

  made of organic materials, e.g. plastics (G02B1/08 takes precedence) · CPC title

• C08B3/00

  Preparation of cellulose esters of organic acids {(rendering cellulose suitable for esterification C08B1/02)} · CPC title

• C08J2301/14

  Mixed esters · CPC title