Process for producing thermoplastic resin hollow molded article

A process for producing a thermoplastic resin hollow molded article, comprising the steps of:

• (a) providing a molding machine comprising first and second mold halves having respective mold surfaces and collectively defining a mold cavity, at least one of the mold halves being movable relative to the other mold half to permit the mold surfaces to be moved both away from each other from a closed state to an unclosed state along a direction of movement and towards each other from the unclosed state to the closed state, at least the first mold half comprising a body and having incorporated therein at least one slidable block, the body and slidable block having respective surfaces that collectively provide the mold surface of the first mold half, the slidable block being movable independently of the body from a first position to a second position, wherein the surface of the slidable block is at a greater distance from the other mold half surface than the surface of the body, to permit expansion of the cavity while the mold halves are maintained in the closed state, the molding machine having means for supplying compressed gas into the cavity;
• (b) supplying a thermoplastic resin in a molten state between the mold surfaces of the first and second mold halves while the mold halves are in the unclosed state;
• (c) moving at least one of the mold halves relative to the other mold half to press and spread the thermoplastic resin so that the cavity is filled with the thermoplastic resin;
• (d) injecting compressed gas into the thermoplastic resin located in the cavity with the supplying means;
• (e) moving the slidable block from the first position to the second position along the direction of movement;
• and
• (f) moving at least one of the mold halves relative to the other mold half to open the mold cavity and removing the thermoplastic resin hollow molded article from the mold cavity.