Flexible device
The present application may provide a flexible device comprising a pressure-sensitive adhesive layer comprising at least first and second regions having different physical properties, wherein the difference in physical properties, such as an elastic modulus or creep strain rate, which are advantageous as the difference in physical properties between the regions increases, is maintained relatively large for each region, and the difference in physical properties, such as a peel force or recovery rate, which are advantageous as the difference in physical properties between the regions decreases, is maintained relatively small for each region.
1. A flexible device, comprising:
a display panel configured to be foldable or rollable through one or more folding axes or rolling axes; and
a pressure-sensitive adhesive layer on one side or both sides of the display panel,
wherein the pressure-sensitive adhesive layer comprises a first region and a second region having different creep strain rates or storage elastic moduli from each other, and
wherein the second region of the pressure-sensitive adhesive layer overlaps the folding axis or the rolling axis,
wherein an absolute value of a difference in storage elastic moduli of the first and second regions according to Equation 5 below is 10% or more, and wherein an absolute value of a difference in peel forces of the first and second regions according to Equation 8 below is 40% or less:
DM 60=100×( M 60.1 −M 60.2)/ M 60.2 [Equation 5]
DPG =100×( PG. 1 −PG. 2)/ PG. 2 [Equation 8]
wherein, D M60 is the difference in the storage elastic moduli, M 60.1 is a storage elastic modulus of the first region at 60° C., and M 60.2 is a storage elastic modulus of the second region at 60° C.; and D PG is the difference in the peel force, P G.1 is a peel force of the first region to a glass, and P G.2 is a peel force of the second region to a glass.
2. The flexible device according to claim 1 , wherein an absolute value of a difference in storage elastic moduli of the first and second regions according to Equation 6 below is 3% or more:
DM 30=100×( M 30.1− M 30.2)/ M 30.2 [Equation 6]
wherein, D M30 is the difference in the storage elastic moduli, M 30.1 is a storage elastic modulus of the first region at 30° C., and M 30.2 is a storage elastic modulus of the second region at 30° C.
3. The flexible device according to claim 1 , wherein an absolute value of a difference in storage elastic moduli of the first and second regions according to Equation 7 below is 1% or more:
D M 20=100×( M 20.1− M 20.2)/ M 20.2 [Equation 7]
wherein, D M20 is the difference in the storage elastic moduli, M 20.1 is a storage elastic modulus of the first region at −20° C., and M 20.2 is a storage elastic modulus of the second region at −20° C.
4. The flexible device according to claim 1 , wherein an absolute value of a difference in peel forces of the first and second regions according to Equation 9 below is 50% or less:
DPI= 100×( PL 1− PL 2)/ PL 2 [Equation 9]
wherein, D PI is the difference in the peel force, P L1 is a peel force of the first region to a polyimide film, and P L2 is a peel force of the second region to a polyimide film.
5. The flexible device according to claim 1 , wherein an absolute value of a difference in creep strain rates of the first and second regions according to Equation 1 below is 20% or more, and an absolute value of the difference in recovery rates of the first and second regions according to Equation 2 below is 15% or less:
DC 60=100×( C 60.1− C 60.2)/ C 60.2 [Equation 1]
DR 60=100×( R 60.1− R 60.2)/ R 60.2 [Equation 2]
wherein, D C60 is the difference in the creep strain rates, C 60.1 is a creep strain rate of the first region at 60° C., and C 60.2 is a creep strain rate of the second region at 60° C.; and D R60 is the difference in the recovery rates, R 60.1 is a recovery rate of the first region at 60° C., and R 60.2 is a recovery rate of the second region at 60° C.
6. The flexible device according to claim 1 , wherein an absolute value of a difference in creep strain rates according to Equation 3 below is 5% or more:
DCM 20=100×( CM 20.1− CM 20.2)/ CM 20.2 [Equation 3]
wherein, D CM20 is the difference in the creep strain rates, C M20.1 is a creep strain rate of the first region at −20° C., and C M20.2 is a creep strain rate of the second region at −20° C.
7. The flexible device according to claim 1 , wherein an absolute value of a difference in recovery rates according to Equation 4 below is 20% or less:
DRM 20=100×( RM 20.1− RM 20.2)/ RM 20.2 [Equation 4]
wherein, D RM20 is the difference in the recovery rates, R M20.1 is a recovery rate of the first region at −20° C., and R M20.2 is a recovery rate of the second region at −20° C.
8. The flexible device according to claim 1 , wherein the pressure-sensitive adhesive layer comprises a crystalline acrylic copolymer.
9. The flexible device according to claim 1 , wherein the pressure-sensitive adhesive layer comprises an acrylic copolymer having a melting point of −20° C. or less.
10. The flexible device according to claim 1 , wherein the storage elastic modulus of the second region at 60° C. is 50,000 Pa or less.
11. The flexible device according to claim 2 , wherein the storage elastic modulus of the second region at 60° C. is 50,000 Pa or less.
12. The flexible device according to claim 3 , wherein the storage elastic modulus of the second region at −20° C. is 500,000 Pa or less.
13. The flexible device according to claim 1 , wherein the peel force of the first region to a glass is at least 500 gf/inch.
14. The flexible device according to claim 4 , wherein the peel force of the first region to a polyimide film is at least 500 gf/inch.