ADHESIVE FILM, OPTICAL MEMBER INCLUDING THE SAME, AND OPTICAL DISPLAY INCLUDING THE SAME
An adhesive film has a glass transition temperature of about −10° C. or less. The adhesive film includes a first region and a second region, the second region being coplanar with the first region. The second region has a higher modulus than the first region at about −20° C. The first region has a modulus of about 0.01 MPa to about 1.5 MPa at about −20° C. The second region has a modulus of about 0.1 MPa to about 50 MPa at about −20° C.
1 . An adhesive film having a glass transition temperature of about −10° C. or lower, the adhesive film including a first region and a second region, the second region being coplanar with the first region, wherein:
the second region has a higher modulus than the first region at about −20° C.,
the first region has a modulus of about 0.01 MPa to about 1.5 MPa at about −20° C., and
the second region has a modulus of about 0.1 MPa to about 50 MPa at about −20° C.
2 . The adhesive film as claimed in claim 1 , wherein the adhesive film has a modulus of about 0.05 MPa to about 5 MPa at about −20° C. and a modulus of about 0.01 MPa to about 1 MPa at about 80° C.
3 . The adhesive film as claimed in claim 1 , wherein the adhesive film has a peel strength ratio of about 1.1 or more, as calculated by Equation 1:
Peel strength ratio= B/A, [Equation 1]
wherein A is peel strength of the adhesive film at 25° C. and B is peel strength of the adhesive film at 60° C.
4 . The adhesive film as claimed in claim 1 , wherein the adhesive film is formed from an adhesive composition including a (meth)acrylic copolymer, a monofunctional (meth)acrylic monomer, a polyfunctional (meth)acrylic monomer, and an initiator.
5 . The adhesive film as claimed in claim 4 , wherein each of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer has a boiling point of about 200° C. or more.
6 . The adhesive film as claimed in claim 4 , wherein each of the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer is a non-urethane based (meth)acrylic monomer.
7 . The adhesive film as claimed in claim 4 , wherein the monofunctional (meth)acrylic monomer includes at least one of isobornyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, stearyl (meth)acrylate, 3-trimethoxysilylpropyl (meth)acrylate, diacetone (meth)acrylamide, (meth)acrylamide, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, ethylene glycolphenylether(meth)acrylate, isodecyl (meth)acrylate, 2-((meth)acryloyloxy)ethyl succinate, isostearyl(meth)acrylate, caprolactone (meth)acrylate, N,N-dimethyl (meth)acrylamide, octyl (meth)acrylate, octadecyl (meth)acrylate, t-butyl (meth)acrylate, hydroxybutyl (meth)acrylate, di cyclopentadiene (meth)acrylate, and an aromatic acrylate.
8 . The adhesive film as claimed in claim 4 , wherein the monofunctional (meth)acrylic monomer is a mixture including a first monofunctional (meth)acrylic monomer, a second monofunctional (meth)acrylic monomer, and a third monofunctional (meth)acrylic monomer in a weight ratio of about 10 to 20:2 to 8:1.
9 . The adhesive film as claimed in claim 8 , wherein:
the first monofunctional (meth)acrylic monomer is at least one of 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, octadecyl acrylate, lauryl acrylate, and t-butyl acrylate;
the second monofunctional (meth)acrylic monomer is at least one of hydroxypropyl (meth)acrylate, hydroxybutyl acrylate, and hydroxyethyl methacrylate; and
the third monofunctional (meth)acrylic monomer is at least one of isobornyl (meth)acrylate, dicyclopentadiene (meth)acrylate, and an aromatic acrylate.
10 . The adhesive film as claimed in claim 4 , wherein the polyfunctional (meth)acrylic monomer includes two to six (meth)acrylate groups.
11 . The adhesive film as claimed in claim 4 , wherein the monofunctional (meth)acrylic monomer and the polyfunctional (meth)acrylic monomer are present in a weight ratio of about 1:1 to 5:1.
12 . The adhesive film as claimed in claim 4 , wherein the (meth)acrylic copolymer is a copolymer of a hydroxyl group-containing (meth)acrylic monomer and an alkyl group-containing (meth)acrylic monomer.
13 . The adhesive film as claimed in claim 4 , wherein the (meth)acrylic copolymer is a copolymer of a hydroxyl group-containing (meth)acrylic monomer, an alkyl group-containing (meth)acrylic monomer, an ethylene glycol unit-containing (meth)acrylate, and a carboxylic acid group-containing monomer.
14 . The adhesive film as claimed in claim 1 , wherein the adhesive film has a peel strength at 25° C. of about 500 gf/in or more with respect to a polyethylene terephthalate film subjected to corona treatment.
15 . The adhesive film as claimed in claim 1 , wherein the adhesive film has a haze of about 1% or less in the visible region.
16 . The adhesive film as claimed in claim I wherein the adhesive film has a total light transmittance of about 90% or more in the visible region.
17 . The adhesive film as claimed in claim 1 , wherein the adhesive film has a number of folding cycles of 50,000 or more at about −20° C. and a radius of curvature of about 5 mm or less.
18 . The adhesive film as claimed in claim 1 , wherein a difference in modulus at about −20° C. between the first region and the second region is about 0.05 MPa or more.
19 . An optical member comprising an optical film and an adhesive film formed on the optical film, wherein the adhesive film includes the adhesive film as claimed in claim 1 .
20 . An optical display comprising the adhesive film as claimed in claim 1 .