US 12,319,801 B2
Hard coating film for foldable display, and application of said film
Yohei Yamaguchi, Otsu (JP); Kokichi Tokuo, Otsu (JP); Shotaro Nishio, Tsuruga (JP); and Kiwamu Kawai, Tsuruga (JP)
Assigned to TOYOBO CO., LTD., Osaka (JP)
Appl. No. 17/625,302
Filed by TOYOBO CO., LTD., Osaka (JP)
PCT Filed Jun. 30, 2020, PCT No. PCT/JP2020/025672
§ 371(c)(1), (2) Date Jan. 6, 2022,
PCT Pub. No. WO2021/010159, PCT Pub. Date Jan. 21, 2021.
Claims priority of application No. 2019-130037 (JP), filed on Jul. 12, 2019.
Prior Publication US 2022/0275159 A1, Sep. 1, 2022
Int. Cl. C08J 7/04 (2020.01); C08J 5/18 (2006.01); C08J 7/043 (2020.01); C09D 5/00 (2006.01); C09D 7/40 (2018.01); C09D 7/45 (2018.01); C09D 7/61 (2018.01); C09D 7/65 (2018.01); C09D 167/02 (2006.01); C09D 175/04 (2006.01); H04M 1/02 (2006.01)
CPC C08J 7/042 (2013.01) [C08J 5/18 (2013.01); C08J 7/043 (2020.01); C09D 5/002 (2013.01); C09D 7/45 (2018.01); C09D 7/61 (2018.01); C09D 7/65 (2018.01); C09D 7/67 (2018.01); C09D 7/68 (2018.01); C09D 167/02 (2013.01); C09D 175/04 (2013.01); H04M 1/0268 (2013.01); C08J 2367/02 (2013.01); C08J 2467/02 (2013.01); C08J 2475/04 (2013.01)] 8 Claims
 
1. A hard coating film for a foldable display, the hard coating film comprising
a polyester film having a thickness of 10 to 80 μm,
an easy-to-adhere resin layer, and
a hard coating layer, the easy-to-adhere resin layer and the hard coating layer being stacked in this order on at least one surface of the polyester film,
wherein
the easy-to-adhere resin layer is a cured product of a composition containing a binder resin and at least one type of particles selected from the group consisting of titanium oxide particles, zirconium oxide particles, and silica particles,
the at least one type of particles have a mean particle size of 5 to 150 nm,
the particles in the easy-to-adhere resin layer are present in a proportion smaller in the direction of the folding portion than in the bending direction, and
the polyester film having the easy-to-adhere resin layer stacked thereon but not yet having the hard coating layer stacked thereon satisfies the following conditions (1) to (4):
(1) the polyester film has a refractive index in the bending direction of 1.590 to 1.620,
(2) the polyester film has a refractive index in the direction of a folding portion of 1.670 to 1.700,
(3) the polyester film has a refractive index in the thickness direction of 1.520 or less, and
(4) the polyester film has a density of 1.380 g/cm3 or more,
wherein the bending direction refers to a direction orthogonal to the folding portion of the polyester film to be folded.