Back to results
US 12,613,552 B2Granted
Surface protection film for flexible display and method of producing thereof
AssigneeBando Chemical Industries, Ltd.
InventorsYutaka Kamada, Masahiro Yamaguchi
Life of this patent
Estimating the term…
Abstract
The present invention addresses the problem of providing a surface protection film for a flexible display in which creases are unlikely to remain. As a solution, provided is the surface protection film for a flexible display that has a protection layer made of polyurethane as an outermost surface thereof, the polyurethane having a stress relaxation rate of 30% or less after 300 seconds at an elongation of 50%.
Claims7
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 polycarbonate-based polyurethane that is a cured product of a material composition containing a polycarbonate polyol, an isocyanate, and an alcohol-based curing agent, wherein in the material composition, an α ratio which is a ratio of the 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 (—OH/—NCO) is 1.05 or more and 1.3 or less,
- a number-average molecular weight of the polycarbonate polyol is 800 or more and 3,000 or less,
- the alcohol-based curing agent contains 1,4-butanediol in a range of 60 to 80 parts by weight, and trimethylolpropane in a range of 20 to 40 parts by weight,
- wherein the stress relaxation rate of the polyurethane after 300 seconds at an elongation of 50% is 30% or less.
1 more element
Dependencies are inferred from the claim text.