Sizing agent applying process for producing carbon fibers, the sizing agent applied carbon fibers, process for producing a carbon fiber reinforced composite material and carbon fiber reinforced composite material

The carbon fiber composition ratio of oxygen to all the elements of 4% or more layers are present in 10nm or more thickness carbon fiber surface, including (A) ~ (C) 80 wt% or more based on the sizing agent total amount combined a sizing agent coating the carbon fiber sizing agent is formed by coating, if implemented 3 times ultrasonic treatment for 10 minutes with acetone solvent, the remaining sizing agent to the sizing agent coated carbon fibers 100 parts by 0. 1 part by mass or more, or less 0.25 mass parts. (A) polyimide, polyetherimide, and at least one member selected from the group consisting of polysulfone (B) a compound having a terminal unsaturated group and polar group in the molecule (C) an epoxy equivalent is less than or equal 250 g / eq , polyether aliphatic epoxy compound having 2 or more epoxy groups in one molecule and / or polyol aliphatic epoxy compound