US 11,969,974 B2
Surface protection film for flexible display and method of producing thereof
Yutaka Kamada, Hyogo (JP); and Masahiro Yamaguchi, Hyogo (JP)
Assigned to BANDO CHEMICAL INDUSTRIES, LTD., Hyogo (JP)
Appl. No. 17/299,790
Filed by BANDO CHEMICAL INDUSTRIES, LTD., Hyogo (JP)
PCT Filed Nov. 29, 2019, PCT No. PCT/JP2019/046707
§ 371(c)(1), (2) Date Jun. 4, 2021,
PCT Pub. No. WO2020/116334, PCT Pub. Date Jun. 11, 2020.
Claims priority of application No. 2018-227956 (JP), filed on Dec. 5, 2018.
Prior Publication US 2022/0040962 A1, Feb. 10, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. B32B 27/08 (2006.01); B29C 43/24 (2006.01); B29C 43/28 (2006.01); B29C 43/30 (2006.01); B32B 7/06 (2019.01); B32B 27/40 (2006.01); C08J 5/12 (2006.01); C08J 5/18 (2006.01); B29K 75/00 (2006.01)
CPC B32B 27/08 (2013.01) [B29C 43/24 (2013.01); B29C 43/28 (2013.01); B29C 43/305 (2013.01); B32B 7/06 (2013.01); B32B 27/40 (2013.01); C08J 5/128 (2013.01); C08J 5/18 (2013.01); B29K 2075/00 (2013.01); C08J 2375/06 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A surface protection film for a flexible display having a protection layer formed of a polyurethane on an outermost surface of the surface protection film for a flexible display,
the polyurethane is a cured product of a material composition containing a polycarbonate polyol, an isocyanate, and an alcohol-based curing agent,
the polyurethane contains 60 to 80 parts by weight of dihydric alcohol and 20 to 40 parts by weight of trihydric alcohol as the alcohol curing agent,
an α ratio of the material composition is 1.05 or more and 1.3 or less, wherein the α ratio is a ratio of a number of moles of hydroxyl groups (—OH) included in the alcohol-based curing agent to a number of moles of isocyanate groups (—NCO) of the isocyanate,
wherein the tan δ peak temperature of the polyurethane, measured under following setting conditions, is 20° C. or higher and 36.4° C. or less, and
the setting conditions are:
Geometry type: tension/compression mode;
Distance between chucks: 20 mm;
Sample width: 5 mm;
Sample thickness: 150 μm;
Frequency: 10 Hz;
Initial temperature: −40° C.;
End temperature: 100° C.;
Rate of temperature increase: 2° C./min; and
Distortion: 0.03%.