WO1998029314A1

WO1998029314A1 - Polymer bottle closed by crown cap or such like

Info

Publication number: WO1998029314A1
Application number: PCT/DK1997/000599
Authority: WO
Inventors: Jan Noerager Rasmussen; Eigil Holdt
Original assignee: Carlsberg A/S
Priority date: 1996-12-30
Filing date: 1997-12-29
Publication date: 1998-07-09
Also published as: AU5312098A

Abstract

There is provided a bottle-shaped container for carbonated beverages including beer. The container has a shape which imparts a high degree of mechanical stability permitting the container to be filled on a conventional filling line for glass bottles. The container is made of a thermoplastic polymer material such as PEN and it comprises a non-threaded neck portion, preferably with a wide mouth opening, to engage a closure element, e.g. a metal foil cap. The container has a fall angle which is at least 12°.

Description

POLYMER BOTTLE CLOSED BY CROWN CAP OR SUCH LIKE

FIELD OF INVENTION

The present invention relates to new bottle-shaped polymer beverage containers of a shape and configuration which confer to the containers improved stability against tipping over on a filling process line and which at the same time render the handling and the use of the containers highly convenient for the consumers .

TECHNICAL BACKGROUND

Over the last decade, beverage containers made of thermoplastic polymer materials such as polyesters have gained increasing importance in packaging and distribution of beverages and other liquids. A particularly significant development has been the provision of refillable, i.e recyclable plastic bottles which can resist repeated washing steps in heated, strongly alkaline cleansing liquids. At present there are several types of polyester materials which have the physical properties required for the purpose of producing refillable containers . Such polymers include polyethylene terephthalate (PET) , acrylonitrile, polyacryla- tes and polycarbonate .

A typical polymeric beverage container, such as the one disclosed in EP 0 445 465, is a blow moulded member of a polyester material formed from a suitable preform and the container typically includes a threaded neck portion for receiving a screw cap closure, a shoulder portion, an elongated container body portion and a container base portion terminating in a chime forming a contact diameter radius which defines a container base area e.g. having an downwardly opening dome configuration. The provision of suitable polyester containers for carbonated beverages involves several difficulties, in particular with respect to selecting polyester materials which form good barriers against carbon dioxide to secure a sufficiently long shelf life of the beverages.

In the context of packaging of carbonated beverages, beer represents a particularly difficult type of beverage, since the sensory quality of beer will deteriorate rapidly if the container material does not exclude permeation of oxygen, carbon dioxide, odours, flavours and/or aroma compounds from the beer through the packaging material or into the beer from the environment .

The above polyester materials are less useful as packaging materials for beer, primarily because they do not have suffi- ciently high barrier properties against permeation of gases, in particular oxygen and carbon dioxide, and against odours, flavours and aroma. Therefore, most beer is presently packaged in metal foil cans or in glass bottles. Recently, however, beer containers which are made from PVC/PVdC copolymer- coated PET have been introduced. From a consideration of surface area to volume relationships and the oxygen permeability of the bottle material, most brewers have tended to use the larger sized bottles, typically 2 L, so as to obtain a satisfactory shelf life of the beer.

Recently, however, new polymer materials have become available which possess improved gas, odour, flavour and/or aroma permeation barrier properties and which at the same time have physical properties which make it possible to provide containers for carbonated beverages including beer which can be refilled or recycled and which permits in-container pasteurization. Such useful polymer materials include polyethylene naphthalate (PEN) , polyketones such as ethylene carbon monoxide copolymer and liquid crystal polymers (LCP) which can be used alone or mixed with other polymers such as e.g. PET. Additionally, with these new materials it has become possible to provide also relatively small containers for carbonated beverages including beer which have a larger surface area to volume ratio than it has hitherto been possible.

It can be envisaged that the availability of such high barrier polymer materials, although these materials are still relatively costly, will stimulate the commercial interest in providing to the marketplace refillable or returnable bottles for carbonated beverages including beer.

However, it is presently a significant problem that plastic bottles due to their low weight and inappropriate shapes that result in a low mechanical stability require a filling line which is specifically adapted to the new containers.

Accordingly, when developing and designing polymer containers which are to replace a conventional type of packaging such as glass bottles for beer, several considerations must be made. Thus, one economically very important aspect is the adaptability of such containers to the conventional process of filling and closing the containers bearing in mind that the weight of a polymer container is much less than that of a glass bottle of the same cubic content for which reason polymer containers generally have significantly less stability against tilting.

Evidently, it is highly advantageous that a plastic bottle can be filled on the same process line as that used for glass containers. Therefore it is one important objective of the invention to provide bottle-shaped polymer containers which are immediately suitable for packaging of carbonated beverages including beer in that they can be filled on existing process lines used for packaging in glass bottles. It has been found that this can be achieved by selecting an appropriate shape and configuration of the polymer container which implies a good stability against tipping over on a conventional glass bottle filling line. Additionally, when shifting from a traditional container type for a particular beverage product such as a glass bottle or a can, it is important from a consumer compliance point of view that the function and design of the bottle is attractive as compared to the conventional packaging type. Thus, it is contemplated that the consumer will be inclined to look for features which are well-known from conventional packagings such as the type of closure element. Thus, as an example, a plastic container for beer having a conventional thread engaged screw cap closure may be less attractive than a container provided with a closure which is not thread engaged. In this connection, consideration must also be given to consumer convenience. Therefore, it is a further objective of the invention to provide a polymer beverage container which has a high consumer compliance.

Thus, it is believed that it is a significant convenience factor that the polymer container has a good stability against tipping over, not only during filling but also in its empty condition, e.g. when the container is handled on retur- ning it to the retail store. Additionally, the container should preferably have a closure which is easy to remove and a neck configuration and a mouth dimension which makes it convenient to consume the beverage directly from the bottle.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a new bottle- shaped container which is particularly useful for packaging of carbonated beverages including beer. The container is a blow-moulded member of a thermoplastic polymer material formed from a preform, said container including (i) a non- threaded neck portion ending in a mouth portion for receiving a closure element, (ii) a shoulder portion, (iii) an elongated container body portion and extending downwardly from the body portion (iv) a container base portion, said base portion terminating in a chime forming a contact diameter radius, the contact diameter radius defining a substantially circular base area having a downwardly opening dome configuration, the quotient between the diameter of said circular base area and the diameter of the container body portion at its transition to the base portion being at least 0.80, characterized in that the fall angle of the container is at least 12°.

DETAILED DISCLOSURE OF THE INVENTION

Thus, the present invention provides a polymer container which is useful for the packaging of carbonated beverages including beer and which is made of a polymer material which has a low permeability for gases, flavour, odour and aroma compounds, which is reusable or recyclable, which permits in- container pasteurization, which has a shape and configuration imparting a high stability against tipping over i.a. permitting it to be filled on a conventional glass bottle filling line, and which has a^' high consumer compliance.

In accordance with the invention the container is typically a blow moulded member of a thermoplastic polymer material formed from a preform by a conventional one or two step blow moulding process during which the material is given a biaxial stretch resulting in an orientation of the material which is adequate to impart on the container (i) the desired permeability properties and (ii) a desired low shrinkage of the material when exposed to heat and detergents during the washing process.

The degree of the biaxial stretch is determined by the type of material and the dimension and the configuration of the preform and that of the resulting container and will for any given preform and container pair vary, also according to the portion of the container. Preferably, however, the biaxial stretch will be at least 1.5 at any point of the container. Typically, the stretch of the polymer material at the transi- tion between the shoulder portion and the body portion is in the range of 5-15, such as in the range of 7-12.

As it is mentioned above, the container according to the invention includes (i) a non-threaded neck portion ending in a mouth portion for receiving a closure element, (ii) a shoulder portion, (iii) an elongated container body portion and extending downwardly from the body portion (iv) a container base portion.

In preferred embodiments, the neck portion is provided with a mouth portion formed so as to receive a closure member, the configuration of the mouth portion depending on the type of closure. In useful embodiments the mouth portion has a toroidal shape and is provided with a contact surface for engaging the closure element. At least part of such a contact surface may be substantially planar.

Presently preferred types of closures include lug caps, spin- on, crimp-on or roll-on closures. However, it is envisaged that crown cork closures can be used as well. In certain preferred embodiments, the container neck portion is provided with a lug or recess to engage the closure skirt. It is preferred that the closure is of a type and configuration which permits it to be fixed to the container on a conventional filling line.

In accordance with the invention, the closure member can be made from metal such as from sheets of tinplate or aluminum, generally with a thickness of about 0.25 mm. The sheets can be coated with lacquers to prevent the metal from reacting with the contents of the container. Alternatively, the closures can be made from a polymer material which e.g. can be compression or injection moulded elements, the former typically being made from urea-formaldehyde or phenolic-formaldehyde resins and the latter from a variety of thermoplastic polymers including polystyrene, low and high density polyethylene, polypropylene and poly (vinyl) chloride. Prefer- ably, the closures are provided with a sealing component or a liner, typically consisting of a cushioning material (a wad) with a facing material, the purpose of which is to isolate the contents of the container from contact with the wad. The wad can e.g. be made from composition cork or pulpboard and faced with either a coated paper, a paper faced with plastic film, a plain metal foil, a lacquered metal foil, or a metal foil faced with a plastic film or coated with a layer of wax material .

The inner face of the closure or the lining material may advantageously be provided with oxygen absorbing or oxygen scavenging compounds to remove headspace oxygen, such as an oxidoreductase, e.g. glucose oxidase which may be entrapped in a microporous gel.

In preferred embodiments, the closure element is provided with a pulling element for convenient removal of the closure. Such an element can form an integrated part of the closure element or it can be a separate element which is firmly attached to the closure. Advantageously, the pulling element has an annular configuration with dimensions permitting it to be removed readily by a finger. The pulling element may be of the same material as the closure element or it may be of a different material.

Additionally, the neck portion of the container may be pro- vided with one or more annular protrusions or flanges to facilitate handling of the container.

It has been found that a wide mouth of the container according to the invention is a factor which plays a significant role for consumer compliance, since drinking directly from the container becomes more convenient. Thus, it may be preferred that the mouth orifice has an inner diameter of at least 20 mm, such as at least 23 mm including at least 25 mm or even at least 28 mm such as at least 30 mm. The container according to the invention has typically a largest outer diameter of the mouth portion which is in the range of 24 to 40 mm such as at least 27 mm including at least 30 mm, e.g. at least 33 or at least 35 mm.

The elongated container body portion can be cylindrical to the whole of its extent, i.e. having essentially parallel side walls. Alternatively, at least part of the container body may have a frustoconical configuration, the remaining part of the body portion being cylindrical. In typical embodiments, the frustoconical part of the container body consti- tutes 50 to 90% of the length of the body portion. The angle between the vertical and the sidewalls of the frustoconical part, if present, may vary but is typically in the range of 5 to 25° such as at the most 10° including an angle of at the most 15°.

The body portion of the container may be provided with one or more annular protrusion or beads with the aims of imparting on the container an improved stability during handling and filling.

The body portion of the container extends into the container base portion, the transition preferably being relatively sharp and terminating in a chime forming a contact diameter radius, the contact diameter radius defining a substantially circular base area having an downwardly opening dome con- figuration (see Figure 1) .

It is an important feature of the container according to the invention that the base portion is capable of resisting a high internal pressure which e.g. occurs during pasteurization of the beverage. Preferably, the container base should have a material dimension and a configuration which permits the internal pressure to be up till 20 bars without any deformation of the base. Additionally, the container should be able to resist negative pressure which occurs during filling of the beverage where vacuum is applied to the con- tainer, e.g. up till about 40% vacuum, such as up till about 50% or even up till about 75% vacuum.

This deformation resistance is achieved partly by providing a relatively large base area and a relatively deep dome con- figuration and partly by having a relatively large wall thickness of the base area. As an example, a container having a cubic content of 0.4 L as illustrated in Figure 1 typically has a wall thickness in the neck portion, the shoulder portion and the body portion which is in the range of 0.3 to 0.6 mm, whereas the material of the base area may have a thickness in the range of 0.5-3 mm, such as in the range of 1-2 mm, e.g. a thickness of at least 1 mm including one of at least 1.5 mm.

As it is described in details in the following, an essential feature of the container according to the invention is its stability against tipping over. This stability characteristic is i.a. provided by forming the base area so that the quotient between the diameter of the circular base area and the diameter of the container body portion at its transition to the base portion is at least 0.80. In preferred embodiments, the quotient is at least 0.85 such as at least 0.90.

An important mechanical characteristic of a polymer bottle, whether filled or empty, is its stability towards tipping over when tilted. Such a tip over stability of the container can e.g. be expressed in terms of the "fall angle", i.e. the minimum angle of inclination (or angle of tilt) at which the bottle tips over, the expressions "angle of inclination" and "angle of tilt" being defined herein as the angle ( ) between the supporting surface and the base of the bottle. The mini- mum angle of inclination at which a bottle will tip over is determined by the radius of the circular base area of the bottle (r) and the height of the centre of gravity (h_G) . Accordingly, the angle of inclination at which a bottle tips over can be calculated according to the following equation: r/h_G = tan a ; a = tan a^{' 1}

It will appear from this equation that a good tip over stability of a bottle can be obtained by increasing the circular base area and/or by lowering the height of the centre of gravity.

Preferably, the bottle shaped container according to the invention has a stability defined as the minimum angle of inclination at which the bottle, when it is placed on a supporting surface of polished stainless steel, tips over which is in the range of 10 to 20° such as in the range of 12 to 18°, e.g. in the range of 13 to 15°. Thus, in advantageous embodiments the container according to the invention has a fall angle of at least 12°, such as at least 13° including at least 14°, e.g. at least 15°.

Generally, a filled bottle-shaped container will have a higher stability against tipping over than has the same bottle in its empty condition. However, the container according to the present invention has a high stability also in the empty condition. Preferably, the difference in angle of inclination at which the bottle tips over when filled and empty, respectively is at the most 2°, more preferably at the most 1° such as at the most 0.5°.

As it is mentioned above, the height of the centre of gravity (h_G) is a factor which is of importance for obtaining a good mechanical stability of the container of the invention. It is preferred that the centre of gravity is located within the body portion of the container, e.g. at a height which is below half the total height of the container.

The container according to the invention may be made from any polymer material which is suitable for packaging of a given particular beverage, the choice of material also depending on whether the container is disposable or is a returnable container, in which latter case the material must have pro- perties permitting the container to resist heat treatment and cleansing substances without unacceptable shrinkage or damages. For carbonated non-beer beverages, the material should also have good gas permeation properties to avoid loss of carbon dioxide. The skilled artisan will, based on his general knowledge, be able to select appropriate available polymer materials for providing a container according to the invention which is suitable for packaging of non-beer beverages. Such well-known polymers include the previously men- tioned polyethylene terephthalate (PET) , acrylonitrile, polyacrylates and polycarbonate and mixtures and copolymers hereof and the more recently introduced PVC/PVdC copolymer- coated PET, the latter material being one example of a multi- layered polymer material which is useful in the present invention. Other known types of such multi-layered or composite polymer materials for the production of containers, including any of the above materials which have been coated with polymer materials conferring a high barrier effect with respect to gases or aroma compounds such as EVOH, are encompassed by the invention.

However, the choice of a suitable material for containers intended for beer packaging is more difficult, since presently relatively few materials suitable for such a purpose is commercially available. Such materials include those men- tioned above including polyethylene naphthalate (PEN) , poly- ketones such as ethylene carbon monoxide copolymer and liquid crystal polymers (LCP) which can be used alone or mixed with other polymers such as e.g. PET. It has also been suggested to use conventionally used polymer materials such as those mentioned above, but coated on one or both faces with high barrier polymers such as e.g. EVOH, for beer containers. A container according to the invention which is useful for packaging of beer and made of such a multi-layered or composite material is also encompassed by the present invention.

In accordance with the invention, a presently preferred polyester material for containers for beer is PEN which may be used alone or optionally in admixture with other polymeric materials such as PET. Thus, a mixture consisting of PEN and up till about 10 wt% of PET may be used. PEN provides desirable characteristics with respect to low permeation rates for oxygen, carbon dioxide, aroma/flavour compounds and odour compounds. Additionally, containers according to the invention made of PEN can be recycled and show only a low shrinkage when subjected to heat treatment. In preferred embodiments, a colouring agent is added to the PEN polymeric material used for beer containers with the objective of protecting against deterioration of the content by light and of improving consumer compliance. The colour of such materials can e.g. be green, amber or brown.

The size of the container can be selected in accordance with consumer demands. Thus, a container according to the invention can have a size of e.g. 0,375 L, 0.4 L, 0.5 L, 0.75 L, 1.0 L or larger such as 1.5 L, 2.0 L or 5.0 L.

In a preferred embodiment of the invention the container is a returnable (refillable) beer bottle made from coloured PEN having a cubic content of about 0.4 L and a weight which is in the range of 35-40 g. It has been found that beer packaged in such a bottle has a shelf life of at least 3 months. Such an embodiment of the present invention will now be described by way of example only with reference to the accompanying drawing in which:

Fig. 1 is a vertical sectional view taken through a container of a configuration to which this invention relates, and

Fig. 2a is a vertical sectional view taken through another container of a configuration to which this invention relates,

Fig. 2b is a sectional view through the section of the neck portion which is encircled on Fig. 2a. The containers shown in Figs . 1 and 2 have a cubic content of about 0.4 L. The total height of the container is 206 mm including non-threaded neck portion provided with a mouth portion defined by an annular toroidal protrusion to receive a closure element as described above and ending in a lug element to hold the closure in position. The neck portion ends in a circumferential flange protrusion. Extending from the ending of the neck portion is a shoulder portion. Beneath the shoulder portion is a body portion which comprises two segments: an upper cylindrical portion and beneath this portion a frustoconical segment which terminates in the base of the dome type as described above . The dome which is defined by a circular arc having a radius of 35 mm is provided with a centrally located projection. The diameter of the circular base area is 47.75 and that of the container body portion at its transition to the base portion is 55 mm, i.e. the quotient between those two diameters is about 0.87.

Claims

1. A bottle-shaped container which is a blow moulded member of a thermoplastic polymer material formed from a preform, said container including (i) a non-threaded neck portion ending in a mouth portion for receiving a closure element, (ii) a shoulder portion, (iii) an elongated container body portion and extending downwardly from the body portion (iv) a container base portion, said base portion terminating in a chime forming a contact diameter radius, the contact diameter radius defining a substantially circular base area having a downwardly opening dome configuration, the quotient between the diameter of said circular base area and the diameter of the container body portion at its transition to the base portion being at least 0.80, characterized in that the fall angle of the container is at least 12°.

2. A container according to claim 1 wherein the quotient between the diameter of said circular base area and the diameter of the container body portion at its transition to the base portion is at least 0.85.

3. A container according to claim 2 wherein the quotient between the diameter of said circular base area and the diameter of the container body portion at its transition to the base portion is at least 0.90.

4. A container according to claim 1 which has a fall angle of at least 13°.

5. A container according to claim 4 which has a fall angle of at least 15°.

6. A container according to claim 4 or 5 wherein the diffe- rence in fall angle of the container in filled and empty condition is at the most 1°.

7. A container according to claim 1 which is made of a polymer material selected from the group consisting of PET, PEN and a mixture of PET and PEN.

8. A container according to claim 7 wherein the polymer material is a mixture of PET and up till 10 wt% PEN.

9. A container according to claim 1 wherein the polymer material comprises a colouring agent.

10. A container according to any of claims 1-9 wherein at least part of the container body portion has a frustoconical configuration.

11. A container according to claim 10 wherein at least part of the container body portion is cylindrical.

12. A container according to any of claims 1-11 wherein the polymer material at the transition between the shoulder portion and the body portion has been given a biaxial stretch in the range of 5-15.

13. A container according to claim 1-12 which can resist an internal pressure of up till 20 bars substantially without any deformation.

14. A container according to claim 1 wherein the container base portion has a wall thickness in the range of 1 to 5 mm.

15. A container according to claim 1 wherein the centre of gravity is located at a height which is below half the height of the entire container.

16. A container according to claim any of claims 1-15 which is provided with a cap closure.

17. A container according to claim 16 wherein the cap closure is provided with a pulling element for removing the closure.

18. A container according to claim 16 wherein the closure is made from a polyester or a metal .

19. A container according to any of claims 1-18 which is a beer bottle made of 100% PEN.

20. A container according to claim 19 which has a volume of about 0.4 L and a weight which in the range of 35-40 g.

21. A container according to claim 1 wherein the mouth portion has an inner opening diameter which is at least 20 mm.

22. A container according to claim 21 wherein the diameter of the opening is at least 25 mm.

23. A container according to claim 1 wherein the mouth portion is torus-shaped and provided with a contact surface for engaging the closure element.

24. A container according to any of claims 21-23 wherein the largest outer diameter of the mouth portion is in the range of 24 to 40 mm.