ADHESIVE COMPOSITION, ADHESIVE FILM, AND FOLDABLE DISPLAY DEVICE COMPRISING SAME
The present invention relates to an adhesive composition including an acrylic polymer having a glass transition temperature of −40° C. or less and a citric acid ester-based compound whose ends are substituted with hydrogen or an alkyl group, an adhesive film, and a foldable display device.
1 . An adhesive composition comprising:
an acrylic polymer having a glass transition temperature of −40° C. or less; and
a citric acid ester-based compound having a hydrogen or an alkyl group at its end.
2 . The adhesive composition of claim 1 , wherein the citric acid ester-based compound has a weight average molecular weight of 1,000 g/mol or less.
3 . The adhesive composition of claim 1 , wherein the alkyl group is an alkyl group having 1 to 10 carbon atoms.
4 . The adhesive composition of claim 1 , wherein the citric acid ester-based compound is comprised in an amount of 5 parts by weight to 30 parts by weight based on 100 parts by weight of the entire acrylic polymer.
5 . The adhesive composition of claim 1 , wherein the acrylic polymer is composed of a polymerization unit of a (meth)acrylic acid ester monomer and a polymerizable monomer having a cross-linkable functional group.
6 . The adhesive composition of claim 5 , wherein the (meth)acrylic acid ester monomer is alkyl(meth)acrylate.
7 . The adhesive composition of claim 5 , wherein the cross-linkable functional group is any one or more selected from the group consisting of a hydroxyl group, an isocyanate group, a glycidyl group, an epoxy group, an amine group, and a carboxyl group.
8 . The adhesive composition of claim 5 , wherein the acrylic polymer is composed of a polymerization unit of 90 to 99.5 parts by weight of a (meth)acrylic acid ester monomer and 0.5 to 10 parts by weight of a polymerizable monomer having a cross-linkable functional group.
9 . The adhesive composition of claim 1 , further comprising a cross-linking agent for the acrylic polymer.
10 . The adhesive composition of claim 9 , wherein the cross-linking agent is comprised in an amount of 0.001 to 5 parts by weight based on 100 parts by weight of the acrylic polymer.
11 . An adhesive film comprising a dried or cured product of the adhesive composition of claim 1 ,
wherein the adhesive film satisfies the following Equations 1 and 2:
1×10 4 ≤G 1′≤1×10 6 [Equation 1]
1×10 4 ≤G 2′≤1×10 5 [Equation 2]
in the Equations 1 and 2,
G1′ is a storage elastic modulus (Pa) at −20° C., and
G2′ is a storage elastic modulus (Pa) at 90° C.
12 . The adhesive film of claim 11 , wherein the adhesive film satisfies the following Equation 3:
Log( G 1′/ G 2′)≤1 [Equation 3]
in the Equation 3,
G1′ is a storage elastic modulus (Pa) at −20° C., and
G2′ is a storage elastic modulus (Pa) at 90° C.
13 . The adhesive film of claim 11 , wherein the adhesive film has a haze of 3% or less at a thickness of 25 μm.
14 . The adhesive film of claim 11 , further comprising any one or more of a release film and a base film provided on one surface or both surfaces of a dried or cured product of the adhesive composition.
15 . A foldable display device comprising the adhesive film of claim 11 .
16 . The adhesive composition of claim 1 , wherein the citric acid ester-based compound is triethyl citrate, acetyl triethyl citrate, tributyl citrate, acetyl tributyl citrate (ATBC), or acetyl trioctyl citrate.