A pressure cylinder made of thin-walled welded stainless steel vessel fitted with a composite shell and a neck with an external and/or internal thread, where the neck is attached to the thin-walled vessel by a circular welded seam with a hermetic seal and containing a flange which is fitted circumferentially with a pair of tapered grooves on its outer surface whose adjacent sides meet on an annular ridge on which there are locking teeth in the direction of the longitudinal axis of the neck and composite fibers are placed in inter-tooth spaces. The method of producing a pressure cylinder includes the welding of a neck to the thin-walled vessel with a hermetic seal, whereupon composite fibers with stress less than the total force acting on the fiber bundle are wound into additional grooves between the teeth and further winding of the fiber around the neck is carried out while simultaneously moving bilaterally along the axis of the shell to position the fiber between the teeth, whereupon fibers with a nominal stress value are wound and final winding of the reinforced composite shell is carried out.

A thermosetting resin composition containing a component (A) that is an epoxy resin, a component (B) that is a (meth)acrylate compound, a component (C) that is an epoxy resin curing agent, and a component (D) that is a thermal radical polymerization initiator, wherein the component (B) contains a component (B1) that is a poly(butadiene-CO-acrylonitrile) having an acryloyloxy group each at both termini and a component (B2) that is a polyfunctional (meth)acrylate other than the component (B1), and the component (C) contains a boron amine complex; a cured product of the thermosetting resin composition; a prepreg; a fiber-reinforced composite material; and a high-pressure gas container containing the fiber-reinforced composite material.