Optical film
Provided are a pressure-sensitive adhesive optical film, a crosslinkable composition, and a display device. A pressure-sensitive adhesive layer using a polymer component exhibiting excellent crosslinking efficiency even at a low molecular weight to exhibit excellent workability, durability and dimension stability, and the optical film to which such a pressure-sensitive adhesive layer is applied may be provided.
1. A pressure-sensitive adhesive optical film, comprising:
an optical member; and
a pressure-sensitive adhesive layer formed on at least one surface of the optical member,
wherein the pressure-sensitive adhesive layer includes a crosslinked product of a crosslinkable composition including a block copolymer including a first block and a second block having a lower glass transition temperature than the first block, and a branched structure in either the first block or the second block.
2. The optical film according to claim 1 , wherein the block copolymer in the pressure-sensitive adhesive layer is realized in at least one structure selected from the group consisting of a sphere structure, a cylinder structure, a gyroid structure and a lamella structure.
3. The optical film according to claim 1 , wherein the glass transition temperature of the first block is in the range of 30 to 200° C.
4. The optical film according to claim 1 , wherein the glass transition temperature of the second block is in the range of −80 to 0° C.
5. The optical film according to claim 1 , wherein the block copolymer includes the first block in the range of 5 to 25 parts by weight and the second block in the range of 75 to 95 parts by weight.
6. The optical film according to claim 1 , wherein the first block includes a polymerization unit of an alkyl methacrylate as a main component.
7. The optical film according to claim 1 , wherein the second block includes a polymerization unit of an alkyl acrylate as a main component.
8. The optical film according to claim 1 , wherein the first block or the second block formed in the branched structure includes a polymerization unit of a (meth)acrylic acid ester monomer and a polymerization unit of a branch-forming monomer.
9. The optical film according to claim 8 , wherein the branch-forming monomer is represented by Formula 1:
where Y is an alkenyl group, an acryloyloxy group, a methacryloyloxy group, an acryloyloxyalkyl group, a methacryloyloxyalkyl group or a haloalkyl group, X is an n valent residue derived from a hydrocarbon group including or not including an oxygen atom, and n is a number in the range of 2 to 6.
10. The optical film according to claim 8 , wherein the branch-forming monomer is represented by any one of Formulas 2 to 5:
where Y 1 and Y 2 are each independently an alkenyl group, an acryloyloxy group, a methacryloyloxy group, an acryloyloxyalkyl group, a methacryloyloxyalkyl group or a haloalkyl group, P and R are each independently an alkylene group or a single bond, Q is an oxygen atom or a single bond, and m is a number in the range of 1 to 10, and
R 1 to R 6 are each independently a hydrogen atom, an alkyl group, an alkenyl group, an acryloyloxy group, a methacryloyloxy group, an acryloyloxyalkyl group, a methacryloyloxyalkyl group or a haloalkyl group, and at least two of R 1 to R 6 are an alkenyl group, an acryloyloxy group, a methacryloyloxy group, an acryloyloxyalkyl group, a methacryloyloxyalkyl group or a haloalkyl group,
where R 7 and R 10 are each independently a hydrogen atom, an alkyl group, an alkenyl group, an acryloyloxy group, a methacryloyloxy group, an acryloyloxyalkyl group, a methacryloyloxyalkyl group or a haloalkyl group, and at least three of R 7 to R 10 are an alkenyl group, an acryloyloxy group, a methacryloyloxy group, an acryloyloxyalkyl group, a methacryloyloxyalkyl group or a haloalkyl group; and
where Y 3 and Y 4 are each independently an alkenyl group, an acryloyloxy group, a methacryloyloxy group, an acryloyloxyalkyl group, a methacryloyloxyalkyl group or a haloalkyl group, and P is an alkylene group.
11. The optical film according to claim 8 , wherein the first block or the second block formed in the branched structure includes 0.01 to 10 mol% of a branch-forming monomer based on a total number of moles of monomers included in the block.
12. The optical film according to claim 1 , wherein the second block is formed in the branched structure.
13. The optical film according to claim 1 , wherein the second block includes a crosslinkable functional group.
14. The optical film according to claim 1 , wherein the second block includes a polymerization unit of an acrylic acid alkyl ester, a polymerization unit of a branch-forming monomer, and a polymerization unit of a copolymerizable monomer having a crosslinkable functional group.
15. The optical film according to claim 14 , wherein a ratio of the number of moles of the second block includes a polymerization unit of an acrylic acid alkyl ester, a polymerization unit of a branch-forming monomer, and a polymerization unit of a copolymerizable monomer having a crosslinkable functional group with respect to a total number of moles of monomers included in the second block.
16. The optical film according to claim 1 , wherein the crosslinkable composition further includes a crosslinking agent.
17. The optical film according to claim 1 , wherein the optical member is a polarizer.
18. A crosslinkable composition, comprising:
a block copolymer including a first block and a second block having a lower glass transition temperature than the first block,
wherein the first block includes a polymerization unit of an alkyl methacrylate as a main component,
wherein the second block includes a polymerization unit of an alkyl acrylate as a main component, and
wherein a branched structure is formed in the second block, and
wherein the second block includes a polymerization unit of a branch-forming monomer represented by Formula 1 below:
wherein Formula 1, Y is an alkenyl group, an acryloyloxy group, a methacryloyloxy group, an acryloyloxyalkyl group, a methacryloyloxyalkyl group or a haloalkyl group, X is an n valent residue derived from a hydrocarbon group including or not including an oxygen atom, and n is a number in the range of 2 to 6,
wherein the second block further includes a polymerization unit of a monomer having a crosslinkable functional group, wherein the crosslinkable functional group is a hydroxyl group, a carboxyl group, an isocyanate group, or an amine group.
19. A display device, comprising:
the optical film of claim 1 .
20. The device according to claim 19 , which comprises a display panel, wherein the pressure-sensitive adhesive optical film is attached to the display panel by means of a pressure-sensitive adhesive layer.