Bottles and jars – End wall structure – One-piece side and end wall
Patent
1996-08-28
1998-02-03
McDonald, Christopher J.
Bottles and jars
End wall structure
One-piece side and end wall
425525, B65D 102
Patent
active
057134804
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a molded plastics bottle, designed in particular to contain still or non-aerated water, or some other non-aerated liquid. It also relates to a mold for making said bottle.
Bottles of this type are made of a plastics material such as, for example, PET (polyethylene terephthalate), PVC (polyvinyl chloride) or other material, by using well known injection blow-molding or extrusion blow-molding techniques. The bottles generally include a neck, designed to receive a closure cap, a cylindrical wall having transverse fluting, and a bottom having a shape designed to impart a certain amount of strength thereto.
It is known in particular to form a rounded indented central portion in the bottom of a bottle of this type, which portion connects with the cylindrical side wall of the bottle via a convex annular surface for standing on the ground which includes radial stiffening grooves or ribs (as described for example in French patents 2 219 077 and 2 300 707).
However, such bottoms always constitute the weak point of the bottles. In particular, vertical drop tests of full bottles demonstrate that the breakage or rupture rate of the bottom is about 70% for a bottle made of PVC falling on its bottom from a height of one meter.
Another drawback of such known bottoms is their low resistance to raised internal pressure, as can result from an increase in the storage temperature of full bottles and/or from shrinkage of the plastics material of the bottles during the two or three weeks following their manufacture and filling. The raised internal pressure in a hermetically sealed bottle results in the bottom becoming deformed and in the bottle becoming unstable.
Furthermore, at present, bottles of this type are packaged and transported in stacked and palletized loads, such that the bottoms of the bottles of the upper layers of a load rest on the tops of the bottles of the lower layers and are subjected by the lower layers to denting and puncturing stresses, which can lead to the bottoms rupturing or becoming permanently deformed, to bottles tilting in the load, and to the palletized loads becoming unstable.
A particular object of the invention is to avoid or at least reduce these drawbacks.
The invention provides a molded plastics bottle having a bottom which presents improved stability and improved resistance to denting.
To this end, the invention proposes a molded plastics bottle, comprising a neck designed to receive a top, a substantially cylindrical side wall and a bottom formed with a concave or indented central portion and a convex peripheral surface which includes radial grooves and which connects with the concave central portion of the bottom via a substantially plane annular surface, the bottle being characterized in that the bottom of each radial groove connects substantially tangentially with said plane annular surface.
In the present description, the curvature of a surface is always defined from the inside to the outside of the bottle, a concave surface thus having its concave face facing towards the outside of the bottle, a convex surface having its convex face facing towards the outside of the bottle.
It has been observed, in surprising manner, that a bottle bottom presenting the above-defined configuration has both stability and resistance to increased internal pressure and to puncturing stresses that are considerably greater than can be obtained in the prior art.
It is particularly because the grooves connect tangentially with the plane surface of the bottom that it is possible to prevent or considerably reduce deformation of the bottom under the effect of pressure variations inside the bottle, thereby guaranteeing its stability.
Advantageously, the radial width of said plane annular surface is greater than the radius of the concave central portion of the bottom of the bottle, and the diameter of said concave central portion of the bottom is less than the diameter of the top which is provided on the neck of the bottle.
In a preferred embodiment of the invent
REFERENCES:
patent: 4850493 (1989-07-01), Howard, Jr.
patent: 4978015 (1990-12-01), Walker
patent: 5198248 (1993-03-01), Krishnakumar et al.
patent: 5287978 (1994-02-01), Young et al.
patent: 5353954 (1994-10-01), Steward et al.
Colloud Alain
Petre Jean-Marie
McDonald Christopher J.
Societe Anonyme Des Eaux Minerales D'Evian
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