Hot fill plastic container with invertible vacuum collapse surfaces in the hand grips

Claim 1

A thin walled plastic container formed by blow molding and adapted to be filled with liquid at a temperature elevated above room temperature, said container comprising an upper portion which includes a sealable closure, a lower base portion closing the bottom of the container and a sidewall portion of generally tubular shape formed integral with and extending between said upper and lower portions, said sidewall portion as formed by blow molding including a substantially diametrically opposed pair of hand grip portions being substantial deviations inward from said generally tubular shape of said sidewall portion and enabling the sidewall portion to be grasped between the thumb and fingers of one hand after the container has been filled with a liquid at an elevated temperature which has cooled to room temperature, said hand grip portions in the container as formed by blow molding and prior to filling with a liquid at an elevated temperature each including an irregularly shaped outwardly bulged surface having an outside edge, and hinge means connected to and extending between said outside edge and the adjacent sidewall portion to enable said bulged surface to invert and thereby accommodate internal forces tending to collapse said sidewall portion inwardly due to filling of the container with said liquid at an elevated temperature and subsequent cooling of the liquid.