Patent attributes
A blow-molded bottle has a flexible concave perimeter surface extending between an upper peripheral margin projecting outward from the bottle neck and an outwardly protruding ring located above the sidewall upper margin. The flexible concave perimeter surface is specially dimensioned to respond to the presence of a vacuum within the bottle by forming linear segments between the upper peripheral margin and the outwardly protruding ring. The average radius of the vertical mid-point of the concave perimeter surface is generally greater than (3/π) (sin π/3) (R1+R2), and less than (6/π) (sin π/6) (R1+R2), where R1 is the outermost radius of the upper peripheral margin, and R2 is the radius of the outwardly protruding ring. The vertical midpoint radius of the flexible concave perimeter surface measured from the vertical axis can be made to vary by between one and five percent at between three and five positions around the perimeter.
