Optical film having excellent restoring force after folding and display device including same

Patent metadata

Field	Value
Publication number	US-2023100624-A1
Application number	US-202117760325-A
Country	US
Kind code	A1
Filing date	Mar 26, 2021
Priority date	Mar 26, 2020
Publication date	Mar 30, 2023
Grant date	—

Abstract

The present disclosure provides an optical film and a display device including the optical film, the optical film comprising a light-transmissive substrate and a buffer layer, wherein a first folded mark parameter calculated by equation 1 ranges from 0.7 to 7.0.

First claim

1 . An optical film comprising:
a light-transmitting substrate; and a buffer layer, the optical film having a first folding mark parameter calculated by the following Equation 1, of 0.7 to 7.0:
First folding mark parameter=[{(thickness of buffer layer×2.0×refractive index of buffer layer)/(thickness of light-transmitting substrate×refractive index of light-transmitting substrate)}+modulus of optical film]×Δn×1.5   [Equation 1]

wherein Δn represents “refractive index of the light-transmitting substrate—refractive index of the buffer layer”.

2 . The optical film according to claim 1 , wherein the buffer layer comprises a urethane acrylate resin.

3 . The optical film according to claim 1 , wherein the buffer layer comprises a urethane acrylate siloxane resin.

4 . The optical film according to claim 3 , wherein the urethane acrylate siloxane resin comprises:
a urethane acrylate silane compound represented by the following Formula 1; an alkoxysilane compound represented by the following Formula 2; and a diol compound represented by the following Formula 3:

wherein R 1 is a functional group derived from a C1-C8 aliphatic or aromatic hydrocarbon, R 2 and R 3 are each independently a C1-C6 linear, branched, or alicyclic alkylene group, R 4 is an acrylate group or methacrylate group, and n is an integer of 1 to 3,
R 5 m Si(OR 6 ) 4-m   [Equation 2]

wherein R 5 and R 6 are each independently a functional group derived from a C1-C8 aliphatic or aromatic hydrocarbon, and m is an integer of 0 to 3,
HO—R 7 —OH

wherein R 7 is a functional group derived from a C1-C6 aliphatic or aromatic hydrocarbon.

5 . The optical film according to claim 4 , wherein R 4 is an acrylate group including a hydroxyl group (—OH).

6 . The optical film according to claim 4 , wherein R 4 is an acrylate group derived from one of 2-hydroxyethyl acrylate (2-HEA) and 4-hydroxybutyl acrylate (4-HBA).

7 . The optical film according to claim 4 , wherein the alkoxysilane compound comprises tetraalkoxysilane.

8 . The optical film according to claim 4 , wherein the diol compound comprises ethylene glycol.

9 . The optical film according to claim 1 , wherein the buffer layer has a thickness of 10 to 150 μm and a refractive index of 1.50 to 1.52.

10 . The optical film according to claim 1 , wherein the light-transmitting substrate has a thickness of 10 to 100 μm and a refractive index of 1.52 to 1.74.

11 . The optical film according to claim 1 , wherein the optical film has a modulus of 2.0 to 7.0 GPa.

12 . The optical film according to claim 1 , further comprising a hard coating layer, wherein the optical film has a second folding mark parameter calculated by the following Equation 2, of 0.7 to 7.0:
Second folding mark parameter=[{((thickness of buffer layer×2.0×refractive index of buffer layer)+(thickness of hard coating layer×refractive index of hard coating layer))/(thickness of light-transmitting substrate×refractive index of light-transmitting substrate)}+modulus of optical film]×Δn×1.5   [Equation 2]
wherein Δn represents “refractive index of the light-transmitting substrate—refractive index of the buffer layer”.

13 . The optical film according to claim 12 , wherein the hard coating layer has a thickness of 0.1 to 10 μm and a refractive index of 1.48 to 1.52.

14 . The optical film according to claim 1 , wherein the optical film has a variation in gloss (ΔRIQ=RIQ 2 −RIQ 1 ) of −20 or more,
wherein, in a bending test based on one bending axis of a sample having a size of 100 mm×50 mm obtained from the optical film, RIQ 1 is a gloss of the sample measured using RIQ (Rhopoint IQ) before the bending test at a predetermined midpoint of the bending axis, and
RIQ 2 is a gloss of the sample measured after the bending test at the same point as the midpoint of the bending axis where RIQ 1 is measured,
wherein the bending test is performed by repeatedly bending the sample having a size of 100 mm×50 mm 100,000 times at a rate of 60 rpm to a radius of curvature of 2.0 mm (diameter of 4.0 mm) at 25° C./50RH % using a repeated bending tester (YUASA).

15 . A display device comprising:
a display panel; and the optical film according to claim 1 , disposed on the display panel.

Assignees

• Kolon Inc

Inventors

• Jung Hak-Gee
• Ahn Sang-Hyun
• Shin Hyora

Classifications

• C08J2383/08

  containing silicon bound to organic groups containing atoms other than carbon, hydrogen, and oxygen · CPC title

• C08L75/06

  from polyesters · CPC title

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title

• C08J7/046 Primary

  Forming abrasion-resistant coatings; Forming surface-hardening coatings · CPC title

• G02B1/04

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