초록 ▼

A container (30d) of polyethylene terephthalate or similar thermoplastic material has a container body (32d), a mouth portion (37d) and a central bottom part (34d). The central bottom part consists of chiefly amorphous and/or thermocrystallized material and forms a bulge directed towards the interio

A container (30d) of polyethylene terephthalate or similar thermoplastic material has a container body (32d), a mouth portion (37d) and a central bottom part (34d). The central bottom part consists of chiefly amorphous and/or thermocrystallized material and forms a bulge directed towards the interior of the container. A ring-shaped or band-shaped standing surface (36d) is arranged adjacent the transition of the bottom part into the container wall (32d). Adjacent to the standing surface the container has a circumferential area of material (35d) which through stretching and/or reshaping has undergone flow and through heating has acquired built-in stresses which tend to contract it. The surrounding circumferential area of material prevents the inward bulge of the central bottom part from straightening out and/or turning inside out when the pressure in the container is increased and/or when the temperature of the container material is raised. The invention also relates to a method and a device for achieving the container.

대표청구항 ▼

A container of polyethylene terphthalate or similar thermoplastic material comprising a body, a closed bottom portion of curved shape which bulges inwardly into the body, and an annular region joining said bottom portion and said body, said annular region providing a standing surface for the contain

A container of polyethylene terphthalate or similar thermoplastic material comprising a body, a closed bottom portion of curved shape which bulges inwardly into the body, and an annular region joining said bottom portion and said body, said annular region providing a standing surface for the container, the material of said body which is joined to said annular region being substantially monoaxially oriented with an orientation corresponding to that arising in a sheet of material which is stretched mono-axially to cause material flow, said annular region including a ring-shaped region which is constituted of material which is oriented and under internal pre-stress tending to contract said ring-shaped region, said internal pre-stress in said ring-shaped region being produced by reshaping said oriented material of said body, the combination of the orientation and internal pre-stress of said ring-shaped region serving as a means for preventing said inwardly curved bottom portion from straightening out or turning inside-out, said bottom portion of curved shape being uniform in thickness and relatively thick compared to said ring-shape region and having a periphery directly connected to said ring-shaped region substantially at said standing surface, said ring-shaped region directly connecting said relatively thick bottom portion to said body substantially at said standing surface, said material of said body having a thickness substantially less than the thick bottom portion to which it is connected by said ring-shaped region, said ring-shaped region providing stable connection of the body with the bottom portion while preventing the inwardly curved bottom portion from straightening out or turning inside-out.