Synthetic resin blow molded multi-layer container having an annular bulging portion at the upper end of the shoulder portion

摘要

PROBLEM TO BE SOLVED: To provide a synthetic resin-made blow-molding (particularly direct blow-molding) multilayer container capable of stably and surely gripping the container by gripper insertion in conveyance of the container between various processes after molding corresponding to speeding up of container production and capable of maintaining the prescribed attitude state of the container.SOLUTION: A synthetic resin-made blow-molding multilayer container comprises a mouth part, an annular recess, a shoulder, a body and a bottom along the axial direction of the container and is composed by an inner surface layer containing an ethylenic resin, a barrier layer and an outer surface layer containing an ethylenic resin in this order from the inside of the container. The mouth part has an external thread area on an outer peripheral face, and the annular recess is contracted in diameter from the external thread area, and then is expanded in diameter to link to the shoulder. The container has an annular expansion portion formed in the upper end of the shoulder by curving the surface of the container inside in the inner surface layer facing the container outside along the axial direction of the container and then curving facing the container inside, and having the thickness of 20-55% with respect to that of the mouth part.