CIRCULARLY POLARIZING PLATE

• US 20200136094A1
• Filed: 07/10/2018
• Published: 04/30/2020
• Est. Priority Date: 07/10/2017
• Status: Active Grant

• Current Assignee: LG Chem Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: YOON, Hyuk, LEE, Nam Jeong, PARK, Jong Sung, PARK, Moon Soo, JUNG, Jae Ho, PARK, Ji Sung, MUN, Byoung Jun
• Granted Patent: US 11,411,206 B2
• Time in Patent Office: Days
• CPC Class Codes: C08F 224/00 Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a heterocyclic ring containing oxygen cyclic esters of polyfunctional acids C08F218/00; cyclic anhydrides of unsaturated acids C08F220/00, C08F222/00
• CPC Class Codes: C08L 25/12 with unsaturated nitriles
• CPC Class Codes: C08L 33/12 Homopolymers or copolymers of methyl methacrylate
• CPC Class Codes: C09D 125/12 with unsaturated nitriles
• CPC Class Codes: C09D 133/12 Homopolymers or copolymers of methyl methacrylate
• CPC Class Codes: C09D 137/00 Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a heterocyclic ring containing oxygen based on polymers of cyclic esters of polyfunctional acids C09D131/00; based on polymers of cyclic anhydrides of unsaturated acids C09D135/00; Coating compositions based on derivatives of such polymers
• CPC Class Codes: C09K 19/3497 the heterocyclic ring containing sulfur and nitrogen atoms
• CPC Class Codes: C09K 19/3809 Polyesters; Polyester derivatives, e.g. polyamides
• CPC Class Codes: C09K 2019/0448 the end chain group being a polymerizable end group, e.g. -Sp-P or acrylate
• CPC Class Codes: G02B 5/208 for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: H10K 50/868 Arrangements for polarized light emission H10K50/86 takes precedence
• CPC Class Codes: H10K 59/50 OLEDs integrated with light modulating elements, e.g. with electrochromic elements, photochromic elements or liquid crystal elements
• CPC Class Codes: H10K 59/8791 Arrangements for improving contrast, e.g. preventing reflection of ambient light

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.

Claims

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 0.1 μ

m to 300 μ

m.

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:

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

18. The circularly polarizing plate according to claim 15, wherein the phase difference layer comprises 40 wt % or more of polymerized units of the reverse dispersion polymerizable liquid crystal compound in polymerized units of the entire polymerizable liquid crystal compound.

19. The circularly polarizing plate according to claim 15, wherein the phase difference layer comprises 30 wt % or more of polymerized units of the polymerizable liquid crystal compound having tri-functionality or more in polymerized units of the entire polymerizable liquid crystal compound.

20. An organic light emitting display device comprising a reflective electrode, a transparent electrode, an organic layer interposed between the reflective electrode and the transparent electrode and having a light emitting layer, and the circularly polarizing plate of claim 1, wherein the circularly polarizing plate is present outside the reflective or transparent electrode and the phase difference layer is disposed closer to the reflective or transparent electrode than the polarizer.