	US 11,997,916 B2
	Polyester film and use thereof
Shotaro Nishio, Tsuruga (JP); Kiwamu Kawai, Tsuruga (JP); Akira Shimizu, Tsuruga (JP); and Katsuya Ito, Osaka (JP)
Assigned to TOYOBO CO., LTD., Osaka (JP)
Appl. No. 17/429,119
Filed by TOYOBO CO., LTD., Osaka (JP)
PCT Filed Jan. 15, 2020, PCT No. PCT/JP2020/001043 § 371(c)(1), (2) Date Aug. 6, 2021, PCT Pub. No. WO2020/162119, PCT Pub. Date Aug. 13, 2020.
Claims priority of application No. 2019-021187 (JP), filed on Feb. 8, 2019; application No. 2019-083808 (JP), filed on Apr. 25, 2019; application No. 2019-090528 (JP), filed on May 13, 2019; application No. 2019-099158 (JP), filed on May 28, 2019; and application No. 2019-130038 (JP), filed on Jul. 12, 2019.
Prior Publication US 2022/0085307 A1, Mar. 17, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. H10K 77/10 (2023.01); B32B 7/023 (2019.01); B32B 7/12 (2006.01); B32B 27/34 (2006.01); H10K 102/00 (2023.01)

CPC H10K 77/111 (2023.02) [B32B 7/023 (2019.01); B32B 7/12 (2013.01); B32B 27/34 (2013.01); B32B 2255/10 (2013.01); B32B 2457/20 (2013.01); H10K 2102/311 (2023.02)]

19 Claims

1. A hard coating film for a foldable display, comprising

(a) a polyester film for a foldable display, which polyester film comprises an easy-to-adhere layer on at least one surface thereof, and

(b) a hard coating layer having a thickness of 1 to 50 μm on the easy-to-adhere layer on at least one surface of the polyester film,

wherein

(1) the polyester film is a biaxially stretched polyethylene terephthalate film having a thickness of 10 to 80 μm,

(2) the polyester film has a refractive index in the bending direction of 1.591 to 1.606,

(3) the polyester film has a refractive index in the direction of a folding portion of 1.670 to 1.700,

(4) the polyester film has a refractive index in the thickness direction of 1.520 or less, and

(5) the polyester film has a density of 1.380 g/cm³or more,

wherein the bending direction refers to a direction orthogonal to the folding portion of the polyester film to be folded.