Foldable backplate film and method for manufacturing foldable backplate film

1. A foldable back plate film comprising:

a foldable back plate comprising a polyimide (PI) substrate, a first adhesive layer provided on an surface of the polyimide substrate, and a second adhesive layer provided on a surface opposite side of the surface of the polyimide substrate in contact with the first adhesive layer;

a first release film provided on a surface opposite side of the surface of the first adhesive layer in contact with the polyimide substrate; and

a second release film provided on a surface opposite side of the surface of the second adhesive layer in contact with the polyimide substrate,

wherein at least one width of the foldable back plate is smaller than a width of each of the first release film and the second release film, the width being a length in a direction perpendicular to the lamination direction of the foldable back plate film, and

wherein a storage modulus at −30° C. of the first adhesive layer and the second adhesive layer is G2, a storage modulus at 60° C. of the first adhesive layer and the second adhesive layer is G3, and G2 and G3 satisfy the following Equations 2 and 3

1×10 4 Pa≤ G 2≤1×10 6 Pa   [Equation 2]

1×10 4 Pa≤ G 3≤1×10 6 Pa.   [Equation 3]

2. The foldable back plate film of claim 1 , wherein a storage modulus (G1) at 20° C. of the polyimide substrate satisfies Equation 1, and

wherein a peel force at 23° C. of the second release film from the second adhesive layer is 20 gf/inch or less, and

a peel force at 23° C. of the first release film from the first adhesive layer is lower than the peel force of the second release film from the second adhesive layer

1 GPa≤G1≤5 GPa.   [Equation 1]

3. The foldable back plate film of claim 1 , wherein an initial adhesive force (gf/inch) of each surface of the first adhesive layer and the second adhesive layer in contact with the polyimide substrate after standing at 23° C. and humidity 50% for 2 hours is A1, and a late adhesive force (gf/inch) of the each surface after standing at 60° C. and humidity 90% for 20 days is A2, and

A1 and A2 satisfy Equation 4:

A 1×0.8≤ A 2.   [Equation 4]

4. The foldable back plate film of claim 1 , wherein an elongation at break at 20° C. of the polyimide substrate is 20% or more and 200% or less.

5. The foldable back plate film of claim 1 , wherein a heat shrinkage at 200° C. of the polyimide substrate is 0.1% or less.

6. The foldable back plate film of claim 1 , wherein a peel force at 23° C. of the first release film from the first adhesive layer is 12 gf/inch or less.

7. The foldable back plate film of claim 1 , wherein the polyimide substrate has a thickness of 20 μm or more and 120 μm or less.

8. The foldable back plate film of claim 1 , wherein each of the first adhesive layer and the second adhesive layer has a thickness of 10 μm or more and 100 μm or less.

9. The foldable back plate film of claim 1 , wherein at least one width of the foldable back plate is R1,

the width of each of the first release film and the second release film is R2, and

R1 and R2 satisfy Equation 5:

1 mm≤ R 2− R 1≤20 mm.   [Equation 5]

10. The foldable back plate film of claim 1 , wherein the first release film and the second release film are each a silicone-based film.

11. The foldable back plate film of claim 1 , wherein each of the first release film and the second release film has a surface resistance of 10 10 Ω/sq or less at 500V or less.