Prepreg means preimpregnated materials. It is sheet type product of reinforced
fiber-immersed matrix and is a kind of intermediate material for composite material
product. Mainly, carbon fiber, grass fiber and aramid fiber are used as reinforced fiber,
and epoxy resin, polyester resin and thermoplastic resin are used as binder.
  There are variety of prepreg products depending on the type of fiber,
the array type of fiber, and the type of binder used. Lately, the composite material using prepreg is widely
used in aerospace industry, general industry, sports and leasure industry because of its improved
characteristics concerning strength, stiffness, corrosion resistance, fatigue, wear resistance,
impact resistance, weight reduction etc.

Carbon fiber is a high strength fiber utilizing the crystal structure of carbon and is most
widely used reinforced fiber in composite material product. Carbon fiber is divided into
PAN series and Pitch series depending on the precursor, and PAN series carbon fiber is
mainly used.