Sizing agent for carbon fibers

Abstract

A sizing agent for carbon fibers includes 2 to 30 parts by weight of a resin main agent (A) having at least one epoxy compound, 2 to 30 parts by weight of a resin main agent (B) having at least one acrylate compound, 0.5 to 15 parts by weight of a surfactant (C), 0.01 to 0.5 parts by weight of a hindered phenol agent (D), and a balance of a solvent, in which a particle diameter of the sizing agent is in a range from 0.01 to 0.5 μm.

What is claimed is: 
     
         1 . A sizing agent for carbon fibers, based on an amount of the sizing agent as 100 parts by weight, wherein the sizing agent comprises:
 2 to 30 parts by weight of a resin main agent (A) having at least one epoxy compound;   2 to 30 parts by weight of a resin main agent (B) having at least one acrylate compound;   0.5 to 15 parts by weight of a surfactant (C);   0.01 to 0.5 parts by weight of a hindered phenol agent (D); and   a balance of a solvent, wherein a particle diameter of the sizing agent is in a range from 0.01 to 0.5 μm.   
     
     
         2 . The sizing agent for the carbon fibers of  claim 1 , wherein the resin main agent (A) having at least one epoxy compound comprises a bisphenol A type epoxy compound, a bisphenol F type epoxy compound, a bisphenol S type epoxy compound, novolac epoxy, or combinations thereof. 
     
     
         3 . The sizing agent for the carbon fibers of  claim 1 , wherein the resin main agent (A) having at least one epoxy compound accounts for 10 to 25 parts by weight. 
     
     
         4 . The sizing agent for the carbon fibers of  claim 1 , wherein an epoxy equivalent of the resin main agent (A) having at least one epoxy compound is in a range from about 100 g/eq to about 1500 g/eq. 
     
     
         5 . The sizing agent for the carbon fibers of  claim 1 , wherein the resin main agent (B) having at least one acrylate compound comprises acrylate having an oxyalkylene group in a molecule, methacrylate having an oxyalkylene group in a molecule, acrylate having an oxyalkyl group in a molecule, methacrylate having an oxyalkyl group in a molecule, acrylate excluding an oxyalkylene group in a molecule, methacrylate excluding an oxyalkylene group in a molecule, acrylate excluding an oxyalkyl group in a molecule, methacrylate excluding an oxyalkyl group in a molecule, or combinations thereof. 
     
     
         6 . The sizing agent for the carbon fibers of  claim 1 , wherein the resin main agent (B) having at least one acrylate compound accounts for 10 to 25 parts by weight. 
     
     
         7 . The sizing agent for the carbon fibers of  claim 1 , wherein the surfactant (C) comprises a non-ionic surfactant, an anionic surfactant, a cationic surfactant, or combinations thereof. 
     
     
         8 . The sizing agent for the carbon fibers of  claim 7 , wherein the non-ionic surfactant comprises an alcohol ethylene oxide additive, polyol polyoxyethylene ether, C16-18 alcohol polyethylene glycol ether, alkyl polyoxyethylene ether, or polyethylene glycol fatty acid ester. 
     
     
         9 . The sizing agent for the carbon fibers of  claim 7 , wherein the non-ionic surfactant comprises polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, or polyethylene glycol bisphenol A derivatives. 
     
     
         10 . The sizing agent for the carbon fibers of  claim 7 , wherein the anionic surfactant comprises alcohol sulfate, alkyl polyethylene glycol ether sulfate, polycyclic phenyl ether polyethylene glycol ether sulfate, alkybenzoyl sulfonate, polycyclic phenyl ether sulfonate, alkyl sulfonate, dialkyl sulfonic succinate, polyoxyethylene nonylphenyl phosphate, triethanolamine polyoxyethylene alkylphenyl ether phosphate, or polyoxyethylene styrenated aryl ether phosphate. 
     
     
         11 . The sizing agent for the carbon fibers of  claim 7 , wherein the cationic surfactant comprises alkyl dimethylphenyl quaternary ammonium salt, alkyl trimethyl quaternary ammonium salt, dialkyl dimethyl quaternary ammonium salt, ester quaternary ammonium salt, imidazoline quaternary ammonium salt. 
     
     
         12 . The sizing agent for the carbon fibers of  claim 1 , wherein the surfactant (C) accounts for 5 to 12.5 parts by weight. 
     
     
         13 . The sizing agent for the carbon fibers of  claim 1 , wherein an amount of the resin main agent (B) having at least one acrylate compound is the same as an amount of the surfactant (C). 
     
     
         14 . The sizing agent for the carbon fibers of  claim 1 , wherein the hindered phenol agent (D) has a structural formula represented by following formula (II): 
       
         
           
           
               
               
           
         
         where R represents long-chain ester. 
       
     
     
         15 . The sizing agent for the carbon fibers of  claim 1 , wherein the hindered phenol agent (D) has a structural formula represented by following formula (II-1): 
       
         
           
           
               
               
           
         
         where n is in a range from 7 to 9. 
       
     
     
         16 . The sizing agent for the carbon fibers of  claim 1 , wherein the hindered phenol agent (D) has a structural formula represented by following formula (II-2). 
       
         
           
           
               
               
           
         
       
     
     
         17 . The sizing agent for the carbon fibers of  claim 1 , wherein the hindered phenol agent (D) accounts for 0.05 to 0.1 parts by weight. 
     
     
         18 . The sizing agent for the carbon fibers of  claim 1 , wherein the solvent is deionized water. 
     
     
         19 . Carbon fibers applied with the sizing agent of  claim 1 , wherein a sizing ratio of the carbon fibers is in a range from 0.1 to 5 weight percent. 
     
     
         20 . Carbon fibers applied with the sizing agent of  claim 1 , wherein an increasing of a hardness of the carbon fibers is less than 100% after 14 days of an age-hardening test.