Circularly polarizing plate

Patent metadata

Field	Value
Publication number	US-11411206-B2
Application number	US-201816628640-A
Country	US
Kind code	B2
Filing date	Jul 10, 2018
Priority date	Jul 10, 2017
Publication date	Aug 9, 2022
Grant date	Aug 9, 2022

Abstract

The present application relates to a circularly polarizing plate and a use thereof. The present application can provide a circularly polarizing plate, which can be applied to a display device such as an organic light emitting display device to minimize blocking of light in the visible light region affecting image quality while blocking harmful ultraviolet rays appropriately and also has excellent durability. In addition, the present application can provide a circularly polarizing plate having excellent compensation characteristics at a viewing angle while ensuring process simplification and cost competitiveness.

First claim

The invention claimed is:

1. A circularly polarizing plate comprising a base film, a phase difference layer on the base film, and a polarizer on the phase difference layer,
wherein the base film comprises an acrylic resin and a styrene-based resin,
the base film has a planar phase difference value of 5 nm or less in Equation 1 below and a thickness direction phase difference value of more than 0 nm in Equation 2 below, and
the phase difference layer has ultraviolet absorptivity such that transmittance for light having a wavelength of 385 nm is 3% or less:
Rin=d ×( nx−ny ),  [Equation 1]

Rth=d ×( nz−ny ),  [Equation 2]

wherein, Rin is the planar phase difference, Rth is the thickness direction phase difference, nx, ny and nz are the refractive indexes of the base film in the slow axis direction, in the fast axis direction and in the thickness direction, respectively, and d is the thickness of the base film.

2. The circularly polarizing plate according to claim 1 , wherein the acrylic resin has one or more ring structures selected from the group consisting of a structure formed by copolymerizing N-substituted maleimide in molecular chains, a lactone ring structure and a glutarimide structure.

3. The circularly polarizing plate according to claim 1 , wherein the styrene-based resin comprises a styrene-acrylonitrile copolymer, a styrene-methacrylic acid copolymer or a styrene-maleic anhydride copolymer.

4. The circularly polarizing plate according to claim 1 , wherein the thickness direction phase difference value of the base film is 50 nm to 120 nm.

5. The circularly polarizing plate according to claim 1 , wherein the base film has a thickness of 1 μm to 300 μm.

6. The circularly polarizing plate according to claim 1 , wherein there is no pressure-sensitive adhesive layer or adhesive layer between the phase difference layer and the base film.

7. The circularly polarizing plate according to claim 1 , further comprising a liquid crystal alignment film or a primer layer between the phase difference layer and the base film.

8. The circularly polarizing plate according to claim 1 , wherein the phase difference layer has an absolute value of a phase difference change ratio according to Equation A below of 17% or less:
Phase difference change ratio=100×( Ra−Ri )/ Ri   [Equation A]

wherein, Ri is the initial in-plane phase difference of the phase difference layer for a wavelength of 550 nm, and Ra is the in-plane phase difference of the phase difference layer for a wavelength of 550 nm after an endurance condition, where the endurance condition is a condition that the phase difference layer is allowed to stand at a temperature of 85° C. for 50 hours or more.

9. The circularly polarizing plate according to claim 1 , wherein the phase difference layer does not contain an ultraviolet absorber having a maximum absorption wavelength in a range of 385 nm to 400 nm.

10. The circularly polarizing plate according to claim 1 , wherein the polarizer is a linear polarizer having single transmittance at a wavelength of 390 nm of 20% to 60%.

11. The circularly polarizing plate according to claim 1 , wherein the phase difference layer has transmittance of 15% or less for light having a wavelength of 390 nm.

12. The circularly polarizing plate according to claim 1 , wherein the phase difference layer has transmittance of 40% or less for light having a wavelength of 400 nm.

13. The circularly polarizing plate according to claim 1 , wherein the phase difference layer has a ratio (R (450)/R (550)) of a planar phase difference (R (450)) for light having a wavelength of 450 nm to a planar phase difference (R (550)) for light having a wavelength of 550 nm in a range of 0.6 to 0.99.

14. The circularly polarizing plate according to claim 1 , wherein the phase difference layer has a ratio (R (650)/R (550)) of a planar phase difference (R (650)) for light having a wavelength of 650 nm to a planar phase difference (R (550)) for light having a wavelength of 550 nm in a range of 1.00 to 1.19.

15. The circularly polarizing plate according to claim 1 , wherein the phase difference layer comprises polymerized units of a normal dispersion polymerizable liquid crystal compound and polymerized units of a reverse dispersion polymerizable liquid crystal compound,
wherein the normal dispersion polymerizable liquid crystal compound and the reverse dispersion polymerizable liquid crystal compound have a ratio (R (450)/R (550)) of a planar phase difference (R (450)) for light having a wavelength of 450 nm to a planar phase difference (R (550)) for light having a wavelength of 550 nm of 0.6 to 0.99 and 1.04-1.25, respectively.

16. The circularly polarizing plate according to claim 15 , wherein the normal dispersion polymerizable liquid crystal compound is represented by Formula 6 below:

wherein, A is a single bond, —C(═O)O— or —OC(═O)— and R 1 to R 10 are each independently hydrogen, halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group or a substituent of Formula 7 below, or two neighboring substituents of R 1 to R 5 or two neighboring substituents of R 6 to R 10 are bonded to each other to constitute a benzene ring substituted with -L-A-P, where L is —C(═O)O—, —OC(═O)— or —OC(═O)O—, A is an alkylene group and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group:

wherein, B is a single bond, —C(═O)O— or —OC(═O)— and R 11 to R 15 are each independently hydrogen, halogen, an alkyl group, an alkoxy group, an alkoxycarbonyl group, a cyano group, a nitro group or -L-A-P, or two neighboring substituents of R 11 to R 15 are bonded to each other to constitute a benzene ring substituted with -L-A-P, where L is —C(═O)O—, —OC(═O)— or —OC(═O)O—, A is an alkylene group and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group.

17. The circularly polarizing plate according to claim 15 , wherein the reverse dispersion polymerizable liquid crystal compound is represented by Formula 1 below:

wherein, R 1 is a substituent of Formula 2 or 3 below, and R 2 to R 6 are each independently hydrogen, an alkyl group, an alkoxy group, a cyano group, a substituent of Formula 4 below or a substituent of Formula 5 below: Here, at least two or more or two of R 2 to R 6 are also substituents of Formula 4 below or substituents of Formula 5 below:
-A 1 -L 1 -Cyc-A 2 -L 2 -P  [Formula 2]

wherein, A 1 and A 2 are each independently an oxygen atom or a single bond, L 1 and L 2 are each independently —C(═O)—O—, —O—C(═O)— or an alkylene group, Cyc is an arylene group or a cycloalkylene group, and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group:

wherein, L 3 and L 4 are each an alkylene group, n is a number in a range of 1 to 4, and P is an acryloyl group, a methacryloyl group, an acryloyloxy group or a methacryloyloxy group or a hydrogen atom:
-A 3 -L 5 -Cyc-A 4 -L 6 -P  [Formula 4]

wherein, A 3 and A 4 are an oxygen atom, an alkylene group or a single bond, L 5 and L 6 are each independently —C(═O)

Assignees

• Lg Chemical Ltd

Inventors

• Yoon Hyuk
• Lee Nam Jeong
• Park Jong Sung
• Park Moon Soo
• Jung Jae Ho
• Park Ji Sung
• Mun Byoung Jun

Classifications

• H10K59/80518

  Reflective anodes, e.g. ITO combined with thick metallic layers · CPC title

• H10K59/8793

  Arrangements for polarized light emission (H10K59/8791 takes precedence) · CPC title

• G02B5/3016

  involving passive liquid crystal elements (optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528) · CPC title

• H10K59/8791

  Arrangements for improving contrast, e.g. preventing reflection of ambient light · CPC title

• G02B5/305

  including organic materials, e.g. polymeric layers · CPC title