US 11,939,499 B2
Multilayer film and use of same
Shotaro Nishio, Tsuruga (JP); Kiwamu Kawai, Tsuruga (JP); and Akira Shimizu, Tsuruga (JP)
Assigned to TOYOBO CO., LTD., Osaka (JP)
Appl. No. 17/614,154
Filed by TOYOBO CO., LTD., Osaka (JP)
PCT Filed May 14, 2020, PCT No. PCT/JP2020/019264
§ 371(c)(1), (2) Date Nov. 24, 2021,
PCT Pub. No. WO2020/241278, PCT Pub. Date Dec. 3, 2020.
Claims priority of application No. 2019-099157 (JP), filed on May 28, 2019.
Prior Publication US 2022/0213350 A1, Jul. 7, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. C09J 7/25 (2018.01); C08J 7/046 (2020.01); G02B 1/14 (2015.01); G06F 1/16 (2006.01)
CPC C09J 7/255 (2018.01) [C08J 7/046 (2020.01); G02B 1/14 (2015.01); C08J 2367/00 (2013.01); C09J 2203/318 (2013.01); C09J 2301/312 (2020.08); G06F 1/1652 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A hard coating film for a foldable display, comprising:
a polyester film having a thickness of from 10 μm to 100 μm; and
an adhesive layer formed on at least one surface of the polyester film,
wherein the polyester film satisfies the following conditions:
(1) a refractive index in a bending direction is from 1.591 to 1.606;
(2) a refractive index in a folding portion direction is from 1.670 to 1.700;
(3) a refractive index in a thickness direction is 1.520 or less; and
(4) a density is 1.380 g/cm3 or more,
wherein the bending direction refers to a direction orthogonal to a folding portion of the polyester film at a time when the polyester film is folded,
wherein the adhesive layer has a thickness of from 1 μm to 50 μm,
wherein the polyester film is a biaxially stretched polyethylene terephthalate film, and
wherein the polyester film comprises an easy-to-adhere layer on at least one surface thereof and a hard coating layer having a thickness of from 1 μm to 50 μm arranged on the polyester film at least on an opposite side to a side of the hard coating film having the adhesive layer.