Dispensing closure structures

A closure structure having a cap part and a movable part, said cap part having a top shaped so as to include two spaced, aligned bearing means located beneath the upper surface of said top and restricted entrances leading into said bearing means, said restricted entrances leading downwardly to said bearing means from the upper surface of said top, said aligned bearing means having an axis, said movable part extending between said bearing means and including two trunnion means, each of said trunnion means fitting within one of said bearing means, at least said cap part being formed of material sufficiently resilient so that said trunnion means can be snapped into said bearing means, said cap part having an opening extending therethrough, said movable part being movable between a closed position in which it closes off said opening and an open position in which said opening is open in which the improvement comprises:

• said material is a hard, somewhat resilient polymer selected from the group consisting of linear polyethylene and polypropylene,
• each of said trunnion means having the shape of a surface of revolution which decreases in diameter in accordance with the distance from that portion of said movable part located between said bearing means,
• each of said bearing means having a shape which substantially corresponds to the shape of the trunnion means within it,
• each of said entrances decreasing in width in accordance with the distance from the space between said bearing means and tapering downwardly into one of said bearing means,
• the rigidity of said cap part being such that said movable part is positioned against any movement in the direction of said axis during and after assembly of said movable part on said cap part as a result of the shapes of said entrances, said bearing means and said trunnion means,
• said shapes of said entrances, said bearing means and said trunnion means tending to minimize concentrations of stresses and strains and to spread stress and strains radially from the central region of said top during assembly of said movable part on said cap part,
• the lengths of said trunnion means being such so as to fit within said bearing means without exerting stress and strains against the ends of said bearing means of smallest dimension.