Hollow molded article and method of producing the same

A hollow molded article having a joining site where two or more split objects are welded by plastic welding and comes into contact with pressurized hydrogen,

• wherein said hollow molded article is composed of a polyamide resin composition,
• said the polyamide resin composition is obtained by blending 0.01 to 10 parts by weight of an amide wax (B) with 100 parts by weight of a polyamide 6 resin (A),
• said the amide wax (B) is an amide compound obtained by reacting a higher aliphatic monocarboxylic acid, a polybasic acid and a diamine,
• said plastic welding is a welding method selected from the group consisting of infrared-ray welding and infrared-ray/vibration welding in which vibration welding is carried out after a welded portion is warmed by infrared rays,
• an average spherulite size in a portion which is 500 μm deep inside from a surface of said hollow molded article is 20 μm or less, and a tensile strength of a test piece containing said joining site of said hollow molded article is 90% or more based on a tensile strength of a test piece not containing said joining site of said hollow molded article, and
• the tensile strength of a test piece containing said joining site of said hollow molded article and the tensile strength of a test piece not containing said joining site of said hollow molded article is measured by:
• welding two or more split objects by plastic welding, a rectangular test piece is cut out from the hollow molded article, a test piece with a short side of 10 mm is prepared such that the joining site welded by plastic welding is positioned at a center in a direction of a long side and perpendicularly to the direction of the long side of the test piece, the tensile strength of a test piece not containing said joining site by plastic welding, a rectangular test piece not containing a site welded by plastic welding and having a short side of 10 mm is prepared such that a tensile test on the hollow molded article can be performed in a same tensile direction as in the tensile test of a test piece of the hollow molded article containing the joining site welded by plastic welding, and after a humidity adjustment under conditions of 23° C./50% RH for 30 minutes, the test pieces are measured for the tensile strength at a tensile speed of 10 mm/min and confirmed.