Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D1/00—Containers having bodies formed in one piece, e.g. by casting metallic material, by moulding plastics, by blowing vitreous material, by throwing ceramic material, by moulding pulped fibrous material, by deep-drawing operations performed on sheet material
  • B65D1/02—Bottles or similar containers with necks or like restricted apertures, designed for pouring contents
  • B65D1/0223—Bottles or similar containers with necks or like restricted apertures, designed for pouring contents characterised by shape
  • B65D1/0261—Bottom construction
  • B65D1/0284—Bottom construction having a discontinuous contact surface, e.g. discrete feet

Definitions

• This invention relates to a plastics bottle for carbonated beverages which has a so-called "petaloid” or "footed” base.
• the base was formed in a domed shape and a separate base cup was used to provide stability to the bottle.
• the base design evolved into a so-called "champagne" base and the now popular petaloid base which typically has up to 7 feet separated by ribs. It is known that such footed bases must meet a number of criteria which in some situations may be at odds with each other. For example, it is essential to minimise stress concentrations so as avoid failure of the base which arises when stress cracks are initiated, particularly when the bottle is filled with a carbonated beverage.
• the base must also be readily blow moulded and should be stable when filled, even when internal pressure changes due to temperature variations for example.
• US-4785949 proposes a design which is said to limit stress levels by maximising the cross sectional areas of the ribs and avoiding sharp transitions between the ribs and feet. This design has a maximum of five feet separated by wide ribs.
• the present invention seeks to provide a container having a base which provides improved stability whilst still ensuring efficient and easy blow moulding of the container .
• a plastics bottle for carbonated drinks including an integral base, the base comprising: a plurality of circumferentially spaced feet separated by valleys which are substantially inverted U shaped and have side walls which are at an angle of 25° or less to each other; and in which each foot has a flat pad, the radially outer edge of which is substantially arcuate, the foot pads together making up a standing surface for the bottle; and the total length of the outer edges of the foot pads is at least 35% of the circumference of the outer edge of the standing surface.
• the base of the bottle of the present invention thus has relatively sharp angled valley side walls in comparison with known bottle base designs and proportionately wide feet.
• the base of the present invention has been found to give excellent stability but also, surprisingly given the large foot pad size, the base is easily moulded and has good stress crack resistance .
• the size of the foot pads will clearly vary according to the number of feet used for a specific base. In order to maintain ease of mouldability, however, it is preferred that the total length of the outer edges of the foot pads is less than 65% of the circumference of the outer edge of the standing surface.
• the length of the outer edge of a foot pad should preferably be between 2 and 4.25 times the width of the narrowest part of a valley, at the base of the inverted U.
• the valleys may be ideally positioned around a substantially hemispherical dome having a central region which comprises an externally convex region surrounded by an externally concave first annulus and an externally convex second annulus which tapers into a foot on one side and blends into the hemispherical valley on the opposite side.
• a blow forming mould has a mould wall which is complementary in shape to the bottle to be formed so that the central convex region of a mould designed to form the bottle of the present invention will receive a preform gate.
• the annuli increase initial stretching of the preform away from its centre, thus keeping the preform away from the mould for as long as possible and limiting stress concentrations in the centre of the final bottle base .
• the bottle base includes five feet.
• the angular extent of a foot pad i.e. the angle which the foot pads subtend at the longitudinal axis of the bottle, may be at least 25°.
• the foot pad is blended into the side wall of the adjacent valley by a radius which, for a five footed base, may be at least 3 mm, but is preferably at least 5 mm.
• Figure 1 is a side view of a bottle according to the invention.
• Figure 2 is a schematic underplan view of the bottle of figure 1;
• Figure 3 is a longitudinal section through the line III-III showing a foot and opposing valley;
• Figure 4 is a developed side section through the section IV-IV which is the standing circumference of the bottle of figures 1 to 3 and shows the foot and valley profile;
• Figure 5 is a similar profile to that of figure 4 for a prior art bottle.
• Figure 1 shows a bottle 1 comprising a neck 2, cylindrical body having side wall 3 and base 5.
• the neck and cylindrical side wall are typical of known PET bottles designed for carbonated soft drinks.
• the novel base 5 of this invention is shown in more detail in figures 2 to 4.
• a preferred embodiment of the invention which is particularly suitable for half litre bottles comprises five feet 10 having a "petaloid" configuration as can be clearly seen in figure 2.
• the feet are equispaced around the base and are separated from each other by valleys 20.
• the base of each foot 10 includes a flat pad 12 such that when the bottle is standing upright the five pads 12 will be in contact with a shelf or table. The five pads thus make up a standing or support surface for the bottle.
• each pad 12 is arcuate in shape so each pad comprises a segment of the support surface.
• the width of the pads themselves may not seem large when compared with the circumference of the standing surface, the side walls 22 of the valleys are sharply inclined, the angle ⁇ between the side walls being less than 25°. As a result, the foot pads 12 are much wider than the bases 24 of the inverted U shaped valleys .
• the angle ⁇ is the angle for the profile of the base which results from a developed (i.e. opened out) section through IV-IV, i.e. the standing circumference of the bottle as shown in figure 3.
• the value of ⁇ is maintained more or less constant radially inwards of the section shown in figure 4 but may open out as the valley blends into the bottle side wall 3 where stiffness is not so critical .
• the width of foot pads 12 is determined by the length of their arcuate outer edges, i.e. If. Although the base 24 of each valley 20 is curved, by treating radius R v as a fillet radius, the width w v of the narrowest part of the valley can be determined. In accordance with the teaching of the present invention, the width of the foot pad w f is ideally between 2 and 4.25 times the valley width w v .
• the foot pads 12 are blended into the valley side walls 22 by a radius Rf which is selected to ensure ease of blowing in spite of the large foot size and narrow valleys .
• Figure 3 shows the configuration at the centre of a five footed bottle base 5.
• the section III-III passes through a hemispherical valley 20 and foot 10.
• an externally convex protrusion 32 In the centre 30 of the base there is an externally convex protrusion 32, surrounded by concave and convex annuli 34 and 36 respectively.
• This shape is selected so that the gate of a preform 4 (shown in dotted lines in figure 1) will not contact the mould until late in the blowing process. This ensures that stress concentrations at the gate region are kept to a minimum.
• the concentric annuli 34, 36 serve to protect the gate region further.
• the bottle shown in figure 1 to 4 has five feet which is suitable for bottles of half and one litre capacity.
• the number of feet may be varied according to the bottle diameter and/or capacity.
• a half litre capacity bottle could conceivably have only four feet, it may be necessary to increase the number of feet to, say, seven for larger bottles. It will be appreciated that the number of feet is therefore not essential to the present invention since it may need to be varied if the criteria which we have found to be critical for combining stability with ease of blowing and minimum stress concentrations are to be met.
• the angular extent ⁇ of each foot pad will also change.
• this angle ⁇ should be at least 25° for optimum stability.
• the radius R f should be at least 3 mm, preferably at least 5 mm.
• the standing diameter D s of the bottle of figures 1 to 4 is at least 70% of the bottle side wall diameter D b .
• Example 1 A five footed bottle similar to that shown in figures 1 to 4 and having a half litre capacity, was blow moulded.
• the critical parameters according to the present invention were as follows:
• the total length of the outer edges of the foot pads is 60 mm which is 39% of the circumference of the standing surface (154 mm) .
• Figure 5 shows a fifth part of a prior art half litre bottle base having five feet. Comparable parameters with those shown in figure 4 have been given like references and differentiated by a dash.
• a and E are the centres of adjacent feet. Thus the distance AE corresponds to the foot spacing F s ' .
• B and D are the radial edges of the flat pads so that AB and DE represent half the width of the pad outer edges.
• C is the centre of the valley.
• the prior art bottle design thus has the following parameters which can be compared with those of the bottle of example 1: Foot pad width l f ' 7.32 mm
• the values given for the bottle of comparative example 1 are typical of prior art five footed bases.
• the angle ⁇ ' would typically be between 50° and 70° and the proportion of foot pad width to standing circumference would generally be between 20 and 25%.
• the bottles of the present invention have been found to provide excellent stability in a wide range of environmental conditions. Furthermore, the bases exhibit fully acceptable stress crack resistance and blowability as required by manufacturers and fillers.

Landscapes

• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Mechanical Engineering (AREA)
• Containers Having Bodies Formed In One Piece (AREA)
• Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
• Laminated Bodies (AREA)
• Cosmetics (AREA)
• Medicines That Contain Protein Lipid Enzymes And Other Medicines (AREA)

Applications Claiming Priority (3)

Publications (2)

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ID=10816919

Family Applications (1)

Country Status (10)

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• 1997
  • 1997-08-05 GB GBGB9716422.2A patent/GB9716422D0/en not_active Ceased
• 1998
  • 1998-07-31 HU HU0003466A patent/HUP0003466A3/hu unknown
  • 1998-07-31 WO PCT/GB1998/002296 patent/WO1999007607A1/en active IP Right Grant
  • 1998-07-31 PL PL98338512A patent/PL338512A1/xx unknown
  • 1998-07-31 AT AT98936563T patent/ATE226167T1/de not_active IP Right Cessation
  • 1998-07-31 EP EP98936563A patent/EP1001902B1/de not_active Expired - Lifetime
  • 1998-07-31 DE DE69808775T patent/DE69808775D1/de not_active Expired - Lifetime
  • 1998-07-31 CA CA002297033A patent/CA2297033A1/en not_active Abandoned
  • 1998-07-31 AU AU85525/98A patent/AU8552598A/en not_active Abandoned
  • 1998-07-31 TR TR2000/00285T patent/TR200000285T2/xx unknown

Non-Patent Citations (1)

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