Adhesive composition

1. A two-part adhesive composition comprising: (A) a first part comprising the following components (a1) to (a5); and (B) a second part comprising the following components (b1) and (b2), based on the total weight of the adhesive composition:

(a1) 30 to 70% by weight of an alkyl(meth)acrylate;

(a2) 1 to 10% by weight of an acrylate containing one or more hydroxy groups in the molecule;

(a3) 20 to 40% by weight of a toughening agent;

(a4) 1 to 10% by weight of a filler, and

(a5) 0.01 to 1% by weight of a carbon nanotube,

(b1) 1 to 10% by weight of an epoxy resin, and

(b2) 1 to 5% by weight of an initiator.

2. The two-part adhesive composition of claim 1 , wherein the (a1) alkyl(meth)acrylate is a (meth)acrylate containing a linear or branched alkyl group having 1 to 20 carbon atoms.

3. The two-part adhesive composition of claim 1 , wherein the (a1) alkyl(meth)acrylate is selected from the group consisting of methyl methacrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, isopropyl(meth)acrylate, n-butyl(meth)acrylate, t-butyl(meth)acrylate, sec-butyl(meth)acrylate, pentyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, isononyl(meth)acrylate, lauryl(meth)acrylate and tetradecyl(meth)acrylate.

4. The two-part adhesive composition of claim 1 , wherein the (a2) acrylate containing one or more hydroxy groups in the molecule is selected from the group consisting of 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 4-hydroxybutyl(meth) acrylate, 2-hydroxyethyleneglycol(meth)acrylate, and 2-hydroxypropyleneglycol(meth)acrylate.

5. The two-part adhesive composition of claim 1 , wherein the (a3) toughening agent comprises any one or a mixture of two or more of those selected from the group consisting of a rubber, a rubber copolymer and a rubber derivative.

6. The two-part adhesive composition of claim 1 , wherein the (a3) toughening agent comprises any one or a mixture of two or more of those selected from the group consisting of vinyl terminated butadiene rubber, chlorinated butadiene rubber, chlorosulfonated butadiene rubber, nitrile butadiene rubber, styrene butadiene rubber, silicone rubber, styrene-butadiene-polymethylmethacrylate triblock copolymer, acrylonitrile-butadiene-styrene copolymer and styrene-butadiene-styrene copolymer.

7. The two-part adhesive comp of claim 1 , wherein the (a4) filler comprises any one or a mixture of two or more of those selected from the group consisting of a silica, a fumed silica and a nanoclay.

8. The two-part adhesive composition of claim 1 , wherein (a5) carbon nanotube has an aspect ratio of 1×10 2 to 1×10 5 .

9. The two-part adhesive composition of claim 1 , wherein the (a5) carbon nanotube has a diameter of 1 to 50 nm and a length of 10 to 120 μm.

10. The two-part adhesive composition of claim 1 , wherein the (a5) carbon nanotube has a BET specific surface area of 150 m 2 /g or more.

11. The two-part adhesive composition of claim 1 , wherein the (a5) carbon nanotube comprises any one or more selected from the group consisting of a single-walled carbon nanotube, a double-walled carbon nanotube and a multi-walled carbon nanotube.

12. The two-part adhesive composition of claim 1 , wherein the (a5) carbon nanotube is present in an amount of 10 to 40 parts by weight based on 100 parts by weight of the (a3) toughening agent.

13. The two-part adhesive composition of claim 1 , wherein a composite is formed by physical bonding between the (a3) toughening agent and the (a5) carbon nanotubes.

14. The two-part adhesive composition of claim 13 , wherein the (a3) toughening agent comprises vinyl terminated butadiene rubber, chlorosulfonated polyethylene, styrene-butadiene-styrene copolymer and acrylonitrile-butadiene-styrene copolymer, and the vinyl terminated butadiene rubber is comprised in an amount of 10 to 30% by weight based on the total weight of the toughening agent; and

the (a5) carbon nanotube is a multi-walled carbon nanotube having an aspect ratio of 5×10 2 to 5×10 4 , a diameter of 5 to 20 nm, a length of 10 to 100 μm, and a specific surface area of 200 m 2 /g to 500 m 2 /g.

15. The two-part adhesive composition of claim 1 , wherein the (b1) expoxy resin is selected from the group consisting of cycloaliphatic epoxide, epoxy novolac resin, bisphenol-A epoxy resin, bisphenol-F epoxy resin, bisphenol-A epichlorohydrin epoxy resin, alkyl epoxide, dicyclopentadiene phenol addition reaction based epoxy resin, limonene dioxide and polyepoxide.

16. The two-part adhesive composition of claim 1 , wherein the (b2) initiator comprises any one or a mixture of two or more of those selected from the group consisting of hydrogen peroxide, alkyl peroxide, alkyl hydroperoxide, arylalkyl peroxide and peroxy ester.

17. The two-part adhesive composition of claim 1 , wherein the (B) second part further comprises a toughening agent in an amount of 50 to 100 parts by weight based on 100 parts by weight of the (b1) epoxy resin.

18. The two-part adhesive composition of claim 1 , further comprising one or more types of additives selected from the group consisting of a polymerizable monomer compound, an adhesion promotor, an inhibitor, an accelerator, an antioxidant, a lubricant, an initiator, an oil, a curing agent, and a curing accelerator.