Receptacles – End wall structure – One-piece side and end wall
Patent
1994-07-22
1995-11-28
Moy, Joseph Man-Fu
Receptacles
End wall structure
One-piece side and end wall
220608, 215373, B65D 638
Patent
active
054699843
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a container of thermoplastic material for containing liquids, the container having a side wall and a base connected to the side wall, the base generally extending transverse to the side wall, the base comprising a curved section connected to the sidewall, a ring-shaped section connected to the curved section , the ring-shaped section having an inclination with respect to a plane perpendicular to a longitudinal axis of the container and a central dome-shaped section connected to the curved section.
BACKGROUND OF THE INVENTION
Such a container is known from the European Patent EP-A-002082.
In this patent a bottle is described which is made of oriented thermoplastic material, such as vinyl chloride-based resins, polymers and co-polymers of acrylic acid or polyesters such as polytherephtalate of ethyleneglycol. In order for the known bottle to have a better resistance to deformation due to build-up of internal pressures and to lateral shocks, such as occur when the bottle is dropped during transportation, the central dome-shaped part has a certain minimum diameter, preferably less than 40% of the total diameter of the bottle.
After blow-moulding of bottles of thermoplastic material, it is for fast production of the bottles required that they release easily from the mould. To reduce the production cycle time, the bottles are released from the mould at the limiting condition of the bottles, and especially the base, being solid but still hot. Bottles having a central dome-shaped part of too small a diameter will, upon opening of the mould, release with difficulty and require removal from the mould by mechanical loosening means or by hand.
Bottles of thermoplastic material that are optimized according to strength, i.e. having relatively thick walls, rather than by using a minimum amount of material, have as a disadvantage that during blow moulding of the bottles, the cooling of the bottles takes longer, such that production rates will be lowered.
It is also known to reinforce the base of bottles of thermoplastic material by, instead of forming a central dome-shaped part, providing the base with a reinforcement rim, or by providing the base with a number of reinforcing depressions. It was found that for bottles containing products such as a bleach containing for example 2% of chlorine were still subject to outward bulging of the base despite reinforcement thereof at elevated temperatures (50.degree. C. and higher) due to large internal pressure build-up. This makes the bottles unstable in the upright position, causing them to fall off shelves or toppling over in kitchen cabinets.
OBJECTS OF THE INVENTION
It is an object of the invention to provide for a container of thermoplastic material that has a large resistance against deformation due to build-up of internal pressure, especially at elevated temperatures.
It is another object of the invention to provide for a container that has a minimum thickness, such that material costs will be as low as possible.
It is again another object of the invention to provide for a container of thermoplastic material that can easily and efficiently be manufactured at high speeds.
SUMMARY OF THE INVENTION
A container of thermoplastic material is thereto characterized in that the central dome-shaped section has in the plane of a cross-section perpendicular to the base, the plane comprising a central, longitudinal axis of the container, a dimension that is larger than 60% of a dimension, d.sub.c, of the container along the cross section, both dimensions being measured in a direction perpendicular to the central, longitudinal axis, the central dome-shaped section comprising a lateral wall of radius of curvature r.sub.1 such that 0.03 d.sub.c <r.sub.1 <0.22 d.sub.c and a cap of radius of curvature r.sub.2 such that 0.3 d.sub.c <r.sub.2 <1.6 d.sub.c.
By the container according to the invention, that is preferably of generally cylindrical shape, but that can be of ellipsoidal or square shape, and at a wall thickness of 1
REFERENCES:
patent: 3727783 (1973-04-01), Carmichael
patent: 4108324 (1978-08-01), Krishnakumar et al.
patent: 4174782 (1979-11-01), Obsomer
patent: 4231483 (1980-11-01), Dechenne et al.
patent: 4978015 (1990-12-01), Walker
patent: 4997692 (1991-03-01), Yoshino
Garner Dean L.
Man-Fu Moy Joseph
The Procter & Gamble & Company
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