Method for manufacturing precursor fiber bundle, method for manufacturing carbon fiber bundle, and carbon fiber bundle

A method for manufacturing a precursor fiber bundle, the method comprising:

• spinning by extruding a spinning solution through a spinneret to produce a coagulated fiber bundle;
• applying an oil agent to the coagulated fiber bundle to produce an oiled coagulated fiber bundle;
• drying and densifying the oiled coagulated fiber bundle to produce a dried and densified coagulated fiber bundle;
• steam stretching the dried and densified coagulated fiber bundle to produce a steam-stretched coagulated fiber bundle;
• applying water to the steam-stretched coagulated fiber bundle to obtain a water-applied coagulated fiber bundle having a moisture content in a range of 25˜50%;
• and
• interlacing the water-applied coagulated fiber bundle by applying a fluid onto the water-applied coagulated fiber bundle.