Method of desizing carbon fiber and method of manufacturing gas diffusion layer of fuel cell thereby

The present invention is characterized in that the carbon fiber in the form of a single fiber with a sizing agent is heat treated at 350 to 900 ° C for 30 to 90 minutes to remove the sizing agent attached to the carbon fiber. In addition， the present invention (i) a process for producing a carbon fiber paper by a wet papermaking method， (ii) a carbon fiber paper impregnated with a thermosetting resin， followed by carbonization and graphitization to produce a gas diffusion layer medium (GDM) and ( Iv) When preparing a gas diffusion layer for a fuel cell through the process of forming a microporous layer by sequentially coating a suspension (Slurry) containing carbon black， a hydrophobic fluorine resin and a solvent on the gas diffusion layer medium (GDM)， the carbon In the process of manufacturing the fiber paper， before dispersing the short-fiber type carbon fiber in a solvent， the short-fiber type carbon fiber is heat-treated at 350-900 ° C. for 30-90 minutes to obtain a sizing agent attached to the carbon fiber. It is characterized by desizing. The present invention can reduce the energy required to remove the sizing agent attached to the carbon fiber and shorten the process time， so it is possible to efficiently remove the sizing agent attached to the carbon fiber. In addition， the present invention can improve the dispersibility of the carbon fiber in a solvent when manufacturing the carbon fiber paper by the papermaking wet method， thereby significantly improving the physical properties and uniformity of the carbon fiber paper， thereby for the fuel cell containing the carbon fiber paper It also improves the physical properties of the gas diffusion layer.