Adhesive composition, adhesive film prepared from the same and display member including the same
An adhesive film has an average slope of about −9.9 to about 0, as measured over a temperature range of about −20° C. to about 80° C. in a graph depicting a temperature-dependent storage modulus distribution of the adhesive film where the x-axis represents temperature (° C.) and the y-axis represents storage modulus (kPa). The adhesive film also has a storage modulus at about 80° C. of about 10 kPa to about 1,000 kPa.
1. An adhesive film having an average slope of about −9.9 to about 0, as measured over a temperature range of about −20° C. to about 80° C. in a graph of storage modulus versus temperature in which the x-axis represents temperature (° C.) and the y-axis represents the storage modulus (kPa), and wherein the adhesive film has a storage modulus at about 80° C. of about 10 kPa to about 1,000 kPa,
the adhesive film being formed from an adhesive composition comprising:
organic particles having a core-shell structure in which a core of the core-shell structure consists of a first copolymer, and a shell of the core-shell structure consists of a second copolymer, the second copolymer being different from the first copolymer, the first copolymer of the shell consisting essentially of one or more polyalkyl (meth)acrylates and the second copolymer of the core consisting essentially of one or more polyalkyl ((meth)acrylates; and
a hydroxyl group-containing (meth)acrylic copolymer that is different from both the first and second copolymers of the organic particles, the hydroxyl group-containing (meth)acrylic copolymer being formed from a monomer mixture, and
the organic particles being present in the adhesive composition in an amount of about 0.5 parts by weight to about 15 parts by weight based on 100 parts by weight of the monomer mixture.
2. The adhesive film according to claim 1 , wherein the adhesive film has a T-peel strength of about 200 gf/in to about 3,000 gf/in, as measured at 25° C. with respect to a non-corona-treated polyethylene terephthalate (PET) film, and the adhesive film has a T-peel strength of about 100 gf/in to about 2,000 gf/in, as measured at 60° C. with respect to a non-corona-treated polyethylene terephthalate (PET) film.
3. The adhesive film according to claim 1 , wherein the adhesive film has a T-peel strength of about 400 gf/in to about 4,000 gf/in, as measured at 25° C. with respect to a corona-treated polyethylene terephthalate (PET) film.
4. The adhesive film according to claim 1 , wherein the adhesive film has a T-peel strength of about 200 gf/in to about 2,000 gf/in, as measured at 60° C. with respect to a corona-treated polyethylene terephthalate (PET) film.
5. The adhesive film according to claim 1 , wherein the organic particles have an average particle diameter of about 10 nm to about 400 nm.
6. The adhesive film according to claim 1 , wherein the monomer mixture comprises a hydroxyl group-containing (meth)acrylate monomer and a comonomer.
7. The adhesive film according to claim 1 , wherein the core and the shell of the core-shell structure of the organic particles have glass transition temperatures satisfying Equation 2:
Tg ( c )< Tg ( s ) Equation 2
wherein Tg (c) is the glass transition temperature (° C.) of the core and Tg (s) is the glass transition temperature (° C.) of the shell.
8. The adhesive film according to claim 7 , wherein the one or more polyalkyl (meth)acrylates of the second copolymer of the core has a glass transition temperature of about −150° C. to about 10° C., and the one or more polyalkyl (meth)acrylates of the first copolymer of the shell has a glass transition temperature of about 15° C. to about 150° C.
9. The adhesive film according to claim 1 , wherein a difference in index of refraction between the organic particles and the hydroxyl group-containing (meth)acrylic copolymer is about 0.5 or less.
10. The adhesive film according to claim 6 , wherein the monomer mixture comprises about 5 wt % to about 40 wt % of the hydroxyl group-containing (meth)acrylate monomer and about 60 wt % to about 95 wt % of the comonomer.
11. The adhesive film according to claim 6 , wherein the comonomer is selected from the group consisting of alkyl (meth)acrylate monomers, ethylene oxide-containing monomers, propylene oxide-containing monomers, amine group-containing monomers, amide group-containing monomers, alkoxy group-containing monomers, phosphoric acid group-containing monomers, sulfonic acid group-containing monomers, phenyl group-containing monomers, silane group-containing monomers, and combinations thereof, and a homopolymer of the comonomer has a glass transition temperature (Tg) of about −150° C. to about 0° C.
12. The adhesive film according to claim 6 , wherein the monomer mixture further comprises a carboxyl group-containing monomer.
13. The adhesive film according to claim 1 , wherein the adhesive composition further comprises at least one of an initiator or a crosslinking agent.
14. The adhesive film according to claim 1 , wherein the adhesive film has a thickness of about 100 μm and a haze of about 5% or less.
15. The adhesive film according to claim 1 , wherein the adhesive film has a thickness of about 100 μm and a haze of about 5% or less, as measured after the adhesive film is subjected to about 200% stretching.
16. The adhesive film according to claim 1 , wherein the adhesive film has a recovery rate of about 30% to about 98%, as calculated by Equation 3:
Recovery rate (%)=(1−( X f /X 0 ))×100 Equation 3
wherein X 0 is an initial thickness of the adhesive film and X f is an increased length of the adhesive film after a specimen comprising a first end of a first PET film attached to the adhesive film which is attached to a second end of a second PET film is pulled to a length of 10 times the initial thickness (X 0 ) of the adhesive film at a rate of about 300 mm/min, maintained in that position for 10 seconds, and then recovered at a rate the same as the pulling rate, followed by application of a force of 0 kPa to the adhesive film.
17. The adhesive film according to claim 1 , wherein the adhesive film has a bubble generation area of about 0%, as measured by folding in half an adhesive film specimen comprising a first PET film having a thickness of about 50 μm stacked on one surface of the adhesive film and a second PET film having a thickness of about 100 μm stacked on a second surface of the adhesive film, followed by placing the adhesive film specimen between parallel frames having a gap of about 1 cm, and then aging the adhesive film specimen at about 70° C. and about 93% RH for about 24 hours.
18. A display member comprising:
an optical film; and
the adhesive film according to claim 1 attached to one or both surfaces of the optical film.