Adhesive composition
Provided are a pressure sensitive adhesive composition, a protective film, an optical film and a display device. The pressure sensitive adhesive composition shows appropriate low-speed and high-speed peel strengths after formation of a cross-linked structure, and has a superior balance between the two. Accordingly, when the pressure sensitive adhesive composition is applied to a protective film, for example, a superior protection effect as well as easy peel-off upon high-speed peeling, which is advantageous for a high-speed process, are shown, and in addition, a superior antistatic property may be obtained during the process.
1. A pressure sensitive adhesive composition, comprising:
a polymer that comprises, as polymerized units, a first monomer which is represented by the following Chemical Formula 1 and in which the total number of carbon atoms in the A and B of Chemical Formula 1 is not less than 1 and less than 3; a second monomer which is represented by the following Chemical Formula 1 and in which the total number of carbon atoms in the A and B of Chemical Formula 1 is not less than 3; and a compound represented by the following Chemical Formula 2, and that satisfies the General Formulae 1 to 3; and
a cross-linking agent including both an aliphatic cyclic isocyanate compound and an aliphatic acyclic isocyanate compound,
wherein the pressure sensitive adhesive composition includes the cross-linking agent in an amount of 4.5 to 10 parts by weight relative to 100 parts by weight of the polymer,
wherein a peel strength of the pressure sensitive adhesive composition, measured at a peel angle of 180 degrees and a peel rate of 30 m/min with respect to an adherent whose surface energy is 30 mN/m or less under a state where a crosslinking structure is formed is from 10 gf/25 mm to 150 gf/25 mm:
wherein Q is hydrogen or an alkyl group, A and B are each independently an alkylene group or an alkylidene group, and n is a number from 0 to 10,
wherein Q is hydrogen or an alkyl group, U is an alkylene group or an alkylidene group, Z is an alkyl group or an aryl group, and m is a number from 1 to 20,
2 ≦O/P≦ 5 [General Formula 1]
O+P≦X [General Formula 2]
1 weight %≦ O+P+X≦ 18 weight % [General Formula 3]
wherein O is an amount by weight % of the first monomer in the polymer, P is an amount by weight % of the second monomer in the polymer, and X is an amount by weight % of the compound of Chemical Formula 2 in the polymer.
2. The pressure sensitive adhesive composition of claim 1 , wherein the number m in the Chemical Formula 2 is from 4 to 8.
3. The pressure sensitive adhesive composition of claim 1 , wherein the Q in the Chemical Formula 2 is an alkyl group having 1 to 4 carbon atoms.
4. The pressure sensitive adhesive composition of claim 1 , wherein the aliphatic cyclic isocyanate compound is an isocyanate compound that is at least one selected from the group consisting of isophorone diisocyanate, methylene dicyclohexyl diisocyanate and cyclohexane diisocyanate; or a dimer or trimer of the isocyanate compound; or a reaction product of the isocyanate compound with a polyol.
5. The pressure sensitive adhesive composition of claim 1 , wherein the aliphatic acyclic isocyanate compound is an alkylene diisocyanate compound having 1 to 20 carbon atoms; a dimer or trimer of the isocyanate compound; or a reaction product of the isocyanate compound with a polyol.
6. The pressure sensitive adhesive composition of claim 1 , further comprising a metal salt.
7. The pressure sensitive adhesive composition of claim 1 , of which a peel strength measured at a peel angle of 180 degrees and a peel rate of 0.3 m/min with respect to an adherent whose surface energy is 30 mN/m or less under a state where a crosslinking structure is formed is from 1 gf/25 mm to 40 gf/25 mm.
8. The pressure sensitive adhesive composition of claim 1 , of which a peel-off constant voltage measured at a peel angle of 180 degrees and a peel rate of 40 m/min with respect to an adherent whose surface energy is 30 mN/m or less under a state where a crosslinking structure is formed is 0.5 kV or less.
9. A protective film, comprising:
a base film for surface protection; and
a pressure sensitive adhesive layer that is formed on one surface of the base film and that comprises a cross-linked product of the pressure sensitive adhesive composition of claim 1 .
10. An optical film, comprising:
an optical device and
the protective film of claim 9 attached to a surface of the optical device.
11. The optical film of claim 10 , wherein a surface-treatment layer whose surface energy is 30 mN/m or less is formed on a surface of the optical device, and the pressure sensitive adhesive layer of the protective film is attached on the surface-treatment layer.
12. The optical film of claim 11 , wherein the surface-treatment layer is a high hardness layer, an anti-glare layer or a low reflection layer.
13. A display device comprising a liquid crystal panel on which the optical film of claim 10 is attached.