Process for production of fiber-reinforced plastic tubing

A process for the production of fiber-reinforced plastic tubing having plural fiber-reinforced plastic intermediate material layers, comprising the steps of:

• laminating two or more fiber-reinforced plastic intermediate material layers, wherein:
• angles of directions of orientation of adjacent layers are the same order but are reversed where the fibers of one layer have an angle of +15° to +75° and the fibers of the adjacent layer has an angle of −15° to −75° with respect to a cored bar, respectively,
• a resin content is provided in the two or more fiber-reinforced plastic intermediate material layers having angles of directions of orientation that are a combination selected from the angle of +15° to +75° and the angle of −15° to −75°, the resin content being 15 to 33 mass %, and
• the laminating step further includes the step of:
• passing the two or more fiber-reinforced plastic intermediate material layers through a belt-type heat press at a roller pressure of 1 kg/cm2 and a temperature of 30° C.;
• putting the laminated fiber-reinforced plastic intermediate material in a bag-like membrane material;
• sealing the membrane material off;
• depressurizing an inside of the bag-like membrane material to a pressure of 60 to 160 mmHg to remove air cells present at the laminated interface;
• wherein the depressurizing step is carried out after the laminating step;
• removing the intermediate material from the bag-like membrane material;
• and
• winding the material on the cored bar to form fiber-reinforced plastic intermediate material layers prior to curing.