Flexible stainless steel foil and flexible light emitting device

Patent metadata

Field	Value
Publication number	US-12460284-B2
Application number	US-202218284260-A
Country	US
Kind code	B2
Filing date	Mar 30, 2022
Priority date	Mar 31, 2021
Publication date	Nov 4, 2025
Grant date	Nov 4, 2025

Abstract

Stainless steel foil with improved durability to repeated bending under the extreme bending conditions demanded of foldable displays and rollable displays. This stainless steel foil is flexible stainless steel foil comprising rolled stainless steel foil with a thickness of 0.1 mm or less, having a tensile strength of 1,800 MPa or more, and having a maximum height roughness of Rz of 0.35 μm or less obtained from a roughness curve of the stainless steel foil surface as measured in the same direction as a tensile direction.

First claim

The invention claimed is:

1 . A flexible stainless steel foil comprising rolled stainless steel foil with a thickness of 0.05 mm or less having a tensile strength of 1,800 MPa or more and a maximum height roughness Rz of 0.35 μm or less obtained from a roughness curve of the stainless steel foil surface measured in the same direction as a tensile direction, wherein, a ratio of a maximum valley depth Rv to the Rz (Rv/Rz) is 0.6 or less, and an elongation at break at the time of measurement of the tensile strength is 1% or more and 2% or less.

2 . A flexible stainless steel foil comprising rolled stainless steel foil with a thickness of 0.1 mm or less having a tensile strength of 1,800 MPa or more and a maximum height roughness Rz of 0.35 μm or less obtained from a roughness curve of the stainless steel foil surface measured in the same direction as a tensile direction, wherein,
when repeatedly bent 180° at a value satisfying R/t=100 (where R is bending radius (mm) and “t” (mm) is thickness) in the same direction as the tensile direction and then back to 0°,
a number of repeated bending operations until a crack with a length of 5 mm or more is formed on a surface of the stainless steel foil is 100,000 or more, and
bending habit is an opened angle of 170° or more.

3 . The flexible stainless steel foil according to claim 1 , wherein,
when repeatedly bent 180° at a value satisfying R/t=100 (where R is bending radius (mm) and “t” (mm) is thickness) in the same direction as the tensile direction and then back to 0°, a number of repeated bending operations until a crack with a length of 5 mm or more is formed on a surface of the stainless steel foil is 100,000 or more, and bending habit is an opened angle of 170° or more.

4 . A flexible stainless steel foil comprising rolled stainless steel foil with a thickness of 0.1 mm or less having a tensile strength of 1,800 MPa or more and a maximum height roughness Rz of 0.30 μm or less obtained from a roughness curve of the stainless steel foil surface measured in the same direction as a tensile direction, wherein
when repeatedly bent 180° at a value satisfying R/t=75 in the same direction as the tensile direction and then back to 0°,
a number of repeated bending operations until a crack with a length of 5 mm or more is formed on a surface of the stainless steel foil is 100,000 or more, and
bending habit is an opened angle of 170° or more when offloading.

5 . The flexible stainless steel foil according to claim 1 , wherein
the Rz is 0.30 μm or less, and, when repeatedly bent 180° at a value satisfying R/t=75 in the same direction as the tensile direction and then back to 0°, a number of repeated bending operations until a crack with a length of 5 mm or more is formed on a surface of the stainless steel foil is 100,000 or more, and bending habit is an opened angle of 170° or more when offloading.

6 . The flexible stainless steel foil according to claim 1 , wherein the stainless steel foil comprising, by mass %, C: 0.15% or less, Si: 1.00% or less, Mn: 2.00% or less, P: 0.045% or less, S: 0.030% or less, Ni: 6.00 to 8.00%, Cr: 16.00 to 18.00%, and N: 0.20% or less, and comprising a martensite phase.

7 . The flexible stainless steel foil according to claim 5 , wherein the stainless steel foil comprising, by mass %, C: 0.15% or less, Si: 1.00% or less, Mn: 2.00% or less, P: 0.045% or less, S: 0.030% or less, Ni: 6.00 to 8.00%, Cr: 16.00 to 18.00%, and N: 0.20% or less, and comprising a martensite phase.

8 . A flexible stainless steel foil comprising rolled stainless steel foil with a thickness of 0.1 mm or less having a tensile strength of 1,800 MPa or more and a maximum height roughness Rz of 0.35 μm or less obtained from a roughness curve of the stainless steel foil surface measured in the same direction as a tensile direction, wherein an area ratio of a martensite phase in a cross-section of the stainless steel foil is 50% or more.

9 . The flexible stainless steel foil according to claim 1 , wherein an area ratio of a martensite phase in a cross-section of the stainless steel foil is 50% or more.

10 . The flexible stainless steel foil according to claim 6 , wherein an area ratio of a martensite phase in a cross-section of the stainless steel foil is 50% or more.

11 . The flexible stainless steel foil according to claim 7 , wherein an area ratio of a martensite phase in a cross-section of the stainless steel foil is 50% or more.

12 . The flexible stainless steel foil according to claim 1 , having a planar shape flexible light emitting electronic element adhered to a surface of the stainless steel foil.

13 . The flexible stainless steel foil according to claim 10 , having a planar shape flexible light emitting electronic element adhered to a surface of the stainless steel foil.

14 . The flexible stainless steel foil according to claim 12 , wherein the flexible light emitting electronic element is an organic EL display element.

15 . A flexible light emitting device comprising the flexible stainless steel foil of claim 1 and a planar shape flexible light emitting electronic element.

Assignees

• Nippon Steel Chemical & Mat Co Ltd

Inventors

• Kimura Keiichi
• Yoshida Yuuki
• Hiraga Takuya
• Fukuda Masahiro
• Kuma Yuji

Classifications

• F21V21/14

  Adjustable mountings · CPC title

• C22C38/40

  with nickel · CPC title

• C22C38/04

  containing manganese · CPC title

• C22C38/02

  containing silicon · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title