Sizing agent for carbon fiber, carbon fiber with improved interfacial adhesion, polymerization reaction type carbon fiber-reinforced polymer composite material using same, and production method therefor

1. A carbon fiber, which is surface-treated with a sizing agent for carbon fiber prepared by urethane bond formation between a compound represented by formula 1 below and a hydroxy group of a phenoxy resin:

In Formula 1, X is a C 2 -C 20 aliphatic, aromatic, alicyclic, or aromatic aliphatic hydrocarbon.

2. A carbon fiber according to claim 1 , wherein the sizing agent is prepared according to production method comprising the following steps:

preparing a block isocyanate compound by reacting ε-caprolactam with one of two isocyanate groups of a diisocyanate compound as shown in Reaction Formula 1 below;

In Reaction Formula 1, X is a C 2 -C 20 aliphatic, aromatic, alicyclic, or aromatic aliphatic hydrocarbon; and

preparing a phenoxy resin modified with caprolactam by reacting the remaining isocyanate group of block isocyanate with a hydroxy group of a phenoxy resin.

3. A carbon fiber according to claim 2 , wherein the diisocyanate compound is one or more aliphatic isocyanates selected from the group consisting of ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), octamethylene diisocyanate, nonamethylene diisocyanate, dodecamethylene diisocyanate, 2,2-dimethylpentane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, decamethylene diisocyanate, butane diisocyanate, 1,3-butadiene-1,4-diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatemethylcaproate, bis(2-isocyanateethyl)fumarate, bis(2-isocyanateethyl)carbonate, bis(isocyanatoethyl) carbonate, bis(isocyanatoethyl)ether, 1,4-butyleneglycoldipropylether-ω,ω′-diisocyanate, and lysinediisocyanatomethylester.

4. A carbon fiber according to claim 2 , wherein the diisocyanate compound is one or more aromatic isocyanates selected from the group consisting of 1,3-phenylene diisocyanate (C 6 H 4 (NCO) 2 ), 1,4-phenylene diisocyanate (C 6 H 4 (NCO) 2 ), toluene-2,4-diisocyanate (CH 3 C 6 H 3 (NCO) 2 ), toluene-2,6-diisocyanate (CH 3 C 6 H 3 (NCO) 2 ), toluene-2,5-diisocyanate (CH 3 C 6 H 3 (NCO) 2 ), toluene-3,5-diisocyanate (CH 3 C 6 H 3 (NCO) 2 ), 1,3-dimethylbenzene-2,4-diisocyanate ((CH 3 ) 2 C 6 H 2 (NCO) 2 ), 1,3-methylbenzene-4,6-diisocyanate ((CH 3 ) 2 C 6 H 2 (NCO) 2 ), 1,4-methylbenzene-2,5-diisocyanate ((CH 3 ) 2 C 6 H 2 (NCO) 2 ), 1-ethylbenzene-2,4-diisocyanate (C 2 H 5 .C 6 H 3 (NCO) 2 ), 1-isopropylbenzene-2,4-diisocyanate (i-C 3 H 7 C 6 H 3 (NCO) 2 ), 1-chlorobenzene-2,4-diisocyanate (ClC 6 H 3 (NCO) 2 ), 1-nitrobenzene-2,4-diisocyanate (O 2 NC 6 H 3 (NCO) 2 ), 1-methoxybenzene-2,4-diisocyanate (CH 3 OC 6 H 3 (NCO) 2 ), 1-methoxybenzene-2,5-diisocyanate (CH 3 OC 6 H 3 (NCO) 2 ), 1-ethoxybenzene-2,4-diisocyanate (C 2 H 5 OC 6 H 3 (NCO) 2 ), azobenzene-4,4′-diisocyanate (OCNC 6 H 4 N═NC 6 H 4 NCO), diphenylether-4,4′-diisocyanate (OCNC 6 H 4 OC 6 H 4 NCO), naphthalene-1,4-diisocyanate (C 10 H 6 (NCO) 2 ), naphthalene-1,5-diisocyanate (C 10 H 6 (NCO) 2 ), naphthalene-2,6-diisocyanate (C 10 H 6 (NCO) 2 ), naphthalene-2,7-diisocyanate (C 10 H 6 (NCO) 2 ), biphenyl-4,4′-diisocyanate (OCNC 6 H 4 C 6 H 4 NCO), 3,3′-dimethyl-biphenyl-4,4′-diisocyanate ([OCN(CH 3 )C 6 H 3 —] 2 ), 3,3′-dimethoxybiphenyl-4,4′-diisocyanate ([OCN(CH 3 O)C 6 H 3 —] 2 ), diphenyldimethylmethane-4,4′-diisocyanate ((CH 3 ) 2 C[C 6 H 4 NCO] 2 ), benzophenone-3,3′-diisocyanate (OC[C 6 H 4 NCO] 2 ), fluorene-2,7-diisocyanate (C 13 H 8 (NCO) 2 ), anthraquinone-2,6-diisocyanate (C 14 H 6 O 2 (NCO) 2 ), 9-ethylcarbazole-3,6-diisocyanate (C 14 H 11 N(NCO) 2 ), pyrene-3,8-diisocyanate (C 16 H 8 (NCO) 2 ), and chrysene-2,8-diisocyanate (C 18 H 10 (NCO) 2 ).

5. A carbon fiber reinforced polymer composite material comprising the carbon fiber of claim 1 ; and a polymer matrix containing the carbon fiber above as a reinforcement.

6. The carbon fiber reinforced polymer composite material according to claim 5 , wherein the carbon fiber is in the form of a dispersion comprising multiple monofilaments or a fibrous assembly selected from the group consisting of plain-woven, knit, braid, non-woven, satin, warp sating and twill.

7. The carbon fiber reinforced polymer composite material according to claim 5 , wherein the polymer matrix is polyamide.

8. A production method of a carbon fiber-reinforced polymer composite material comprising the following steps:

surface-treating a carbon fiber with a sizing agent for carbon fiber prepared by urethane bond formation between a compound represented by formula 1 below and a hydroxy group of a phenoxy resin;

In formula 1, X is a C 2 -C 20 aliphatic, aromatic, alicyclic, or aromatic aliphatic hydrocarbon;

impregnating a monomer in which ε-caprolactam is impregnated in the carbon fiber surface-treated with the sizing agent above; and

polymerizing a monomer in which the impregnated ε-caprolactam is polymerized.

9. The production method of a carbon fiber-reinforced polymer composite material according to claim 8 , wherein the step of polymerizing a monomer is accomplished by the sizing agent coated on the surface of the carbon fiber playing a role of an initiator to induce polymerization of ε-caprolactam.

10. The production method of a carbon fiber-reinforced polymer composite material according to claim 8 , wherein the step of polymerizing a monomer is accomplished with ε-caprolactam by using an additional initiator.

11. The production method of a carbon fiber-reinforced polymer composite material according to claim 8 , wherein the carbon fiber is in the form of a dispersion comprising multiple monofilaments or a fibrous assembly selected from the group consisting of plain-woven, knit, braid, non-woven, satin, warp sating and twill.