Beer container and method of producing same

Abstract

A method of forming a plastic beer drinking container includes providing an injection molding body having a base portion and two enclosing sidewall portions and providing a molding ram configured to be received within the molding body defining a molding cavity therebetween. A plurali ty of spaced base portion pins each extend a prede termined height from the base. Plastic is injected into the cavity to injection mold a container form and then blowing the container form and extending the base pins a predetermined distance into the cavity whereby the pins each leave a corresponding raised nucleation site projecting upwardly within a molded container.

Description

BEER CONTAINER & METHOD OF PRODUCING SAMEField

[0001] The invention relates to containers and, in particular, to a beer container and method of forming same.

[0002] The invention has been developed primarily for use in forming molded plastic beer drinking containers and will be described hereinafter with reference to this application. However, it will be appreciated that the invention is not limited to drinking containers.Background

[0003] Beer glasses are ubiquitous and in more recent times have been desired to be formed of materials that are more resistant to breakage than glass, and that also do not present a sharps hazard when broken. A solution was to provide beer drinking containers formed from plastic materials.

[0004] T he inner surfaces of beer glasses is smooth and when a carbonated beer, or other beverage, is poured into the glass it’s inner surface causes effervescence. This results in a bubbling resulting in a surface foam. Irregularities, known as nucleation sites, in the glass container surface promote the occurrence of bubbling from the dissolved gas.

[0005] In order to promote the bubbling, roughened or etched inner surfaces, typically the base, are provided to act as nucleation sites. Carbonated beers including ales, lagers, pilsners, stouts, etc., are expected to be served in drinking containers that allow generation of bubbles at some rate and to provide a foamy or creamy head. It will be appreciated that an excess bubbling rate is undesirable as this will cause the beer to lose it carbonation and go ‘flat’. In the converse, too little bubbling provides no to little foaming which is also undesirable to consumers.

[0006] It is known to provide a beer drinking container having smooth inner surfaces from plastics such as polycarbonate due to its shatter resistance. This provide little foaming and it is known to include smooth walls and a nucleation site at or near the base to stimulate bubbling. Il ls known larger nucleation site results in a faster release of bubbles but as above there is a limit to the release.

[0007] In practice, molded beer drinking containers are known to be formed from plastics and are often modified to provide the nucleation sites by means of machine stamping on the inside base of the container, and also by means of etching or abrading the base. However, it is believed the stamping of nucleation sites does not provide a reliable foaming rate and etching or abrading causes an additional step in the manufacturing process which are both undesirable.Further, whilst it is known to use coating materials on the inside of plastic beer drinking containers, this is not only an additional step in the manufacturing process it also adds cost for the material to be included in conventional apparatus to be modified to accommodate same.Object of Invention

[0008] The object of the invention is a desire to provide a molded beer container and method of making same that will overcome one or more of the disadvantages of the prior art, or to provide a useful alternative.Summary of Invention

[0009] According to a first aspect of the invention there is provided a method of forming a plastic beer drinking container comprising the steps of: providing an injection molding body having a base portion and two enclosing sidewall portions; providing a molding ram configured to be received within the molding body and configured to define a molding cavity therebetween; disposing a plurality of spaced base portion pins each extending a predetermined distance from the base; injecting plastic into the cavity to injection mold a container form; and blowing the container form and extending the base pins a predetermined distance into the cavity whereby the pins each leave a corresponding raised nucleation site projecting upwardly within a molded container.

[0010] According to another aspect of the invention there is provided a method of forming a plastic beer drinking container comprising the steps of: injection molding a container form; and blowing the container form forcing a plurality of spaced apart pins into the base from a first side of the base to form corresponding raised nucleation sites on a second side of the base.

[0011] It can therefore be seen there is advantageous provided a method of forming a plastic beer drinking container have nucleation sites provided on the inside of base and that are formed from the outside of the base. No additional manufacturing steps such as scratching or abrasion on the base is required, nor is the use of an coating material within the formed container.Brief Description of Drawings

[0012] A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0013] Fig. 1 is a close up side-view of a lower part of a container formed according to the method of the preferred embodiment;

[0014] Fig. 2 is a bottom view of the container of Fig. 1;

[0015] Fig. 3 is a top view of the container of Fig. 1;

[0016] Fig. 4 is a side view of the container of Fig.1 containing beer;

[0017] Fig. 5 shows various views of the Mold used for forming the container of Fig. 1.Description of Embodiments

[0018] Referring to the drawings generally, there is shown a molded plastic beer drinking container and molds used in molding same. In the preferred embodiment, the plastic beer drinking container is formed by providing an injection molding body having a base portion and two enclosing sidewall portions.

[0019] A molding ram is provided to be disposed within the mold base and side wall portions. The ram when inserted forms a defines molding cavity between the ram and the side wall and base portions of the mold. A heated plastic is injected into the cavity to form the container in a conventional manner.

[0020] In the preferred embodiment, the mold body base portion includes a plurality of spaced base portion pins each extending a predetermined height from the base into the mold cavity. When the plastic is injected into the cavity and a container form is created. Whilst still hot, the container form is blown and the pins are moved towards and into the base to each provide a corresponding raised nucleation site on the opposite side (inside) of the base. The base is convex shaped extending into the cavity, and is flat on a lower or outside face of the base.

[0021] That is, the containers or cups are formed from a two step molding process. The first is an injection mold technique which forms a relatively thick and basic form of the container (shown in the preferred embodiment as a 'schooner cup'). The second subsequent step in the process, where the beer container is wider in the middle than at its base or opening and whereby the mold part cannot be extracted and the blow molding technique blows the still soft plastic material formed by the injection process into a second mold to form the final shape. It is during the second step that the base is stamp from below or outside the container to form the nucleation sites on the inside of the base.

[0022] The raised nucleation sites project from the base of the formed container away from the base a predetermined height. In the preferred embodiment, the pins form nucleation sites having a height from the base of 0.75mm to 1.75mm, most preferably 1mm. Further, the nucleation sites in the preferred embodiment have a width of between 0.5mm to 1.75mm and most preferably 1.25mm.

[0023] As best seen in Fig. 5, the base pins of the preferred embodiment are substantially circular in cross-section and extend perpendicularly from the base. It will be appreciated, however, the pins can be polygonal in cross-section or be irregular or not uniform in crosssection. Most preferably, the pins each include a rounded or chamfered end but the pin ends may in some embodiments be substantially right cylindrical.

[0024] The pins are disposed in a substantially regular square array about the mold base portion. Additionally, a line of three pins extend a predetermined distance from each diagonalin the square array. A circular array of pins can alternatively be provided, as can an irregular or unorganized array.

[0025] In the mold of Fig. 5, the base includes approximately 65 pins however it will be appreciated any preferred number of pins can be used. Preferably, between 1 and 150 pins are provided depending on the diameter of the beer container.

[0026] As shown, the array of pins are disposed about a centre of the base and are a predetermined distance therefrom. The array forms an annulus portion over the base about the centre and the pins terminate. This way, the base includes a flat base portion about the centre, and a flat base portion adjacent the circumference.

[0027] In forming the plastic beer drinking container, a copolymer plastic in the form of a combination of dimethyl terephthalate (DMT), cyclohexanedimethanol (CHDM), and 2, 2,4,4- tetramethyl-l,3-cyclobutanediol (CBDO) monomers is injected into the assembled mold. In the preferred embodiment where the body of the container is wider than the base or the top, a sidewall portion is blown or blow molded. The mold base portion pins are then forced from beneath the mold base towards the top of the side wall portion by an amount of the height of the pins.

[0028] The pins to do not break the molded base of the container but instead cause corresponding raised nucleation sites in the container base that extend into the container. The nucleation sites are advantageously provided during the molding process and do not require scratching or abrasion, or the addition of a coating or other treatment to provide nucleation sites.

[0029] It can be seen the nucleation sites are created by pushing mold base pins up through the base of the container as it is being manufactured and while the plastic is still malleable. The container of the preferred embodiment has a base circumference of approximately 55mm and includes approximately 65 raised nucleation sites. The waist of the molded beer container of the preferred embodiment is wider (approximately 80mm) than the base or the opening at the upper end of the side wall. Most preferably, the nucleation sites are disposed about the centre of the base. The height of the container of the preferred embodiment is approximately 145mm with a base thickness between 4 to 15mm.

[0030] It will be appreciated the method of the preferred embodiment pushes or punches pins into the formed container before it is cooled without breaking the surface. This overcomes the problem of creating nucleation sites inside a container manufactured using injection and blow molded plastic. This is because these manufacturing processes force plastic and air from the inside of the container outwardly creating an even, flat internal finish.

[0031] The foregoing describes only one embodiment of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope of the present invention.

[0032] The term “comprising” (and its grammatical variations) as used herein is used in the inclusive sense of “including” or “having” and not in the exclusive sense of “consisting only of’.

Claims

CLAIMS1 . A method of forming a plastic beer drinking container comprising the steps of: providing an injection molding body having a base portion and two enclosing sidewall portions; providing a molding ram configured to be received within the molding body and configured to define a molding cavity therebetween; disposing a plurality of spaced base portion pins each extending a predetermined distance from the base; injecting plastic into the cavity to injection mold a container form; and blowing the container form and extending the base pins a predetermined distance into the cavity whereby the pins each leave a corresponding raised nucleation site projecting upwardly within a molded container.

2. A method according to claim 1 wherein the nucleation sites extend within a molded container 0.75mm to 1.75mm.

3. A method according to claim 1 wherein the nucleation sites have a width of 0.75mm to 1.25mm.

4. A method according to claim 1 wherein the pins are circular or polygonal in crosssection.

5. A method according to claim 1 wherein the pins are substantially disposed in a regular array.

6. A method according to claim 5 wherein the pins are substantially disposed in a substantially square array.

7. A method according to claim 6 including a line of pins extending a predetermined distance from each diagonal in the square array.

8. A method according to claim 1 where in the pins are disposed about an annulus of the base.

9. A method according to claim 1 wherein the base is concave and the pins extend perpendicularly therefrom.

10. A method according to claim 1 wherein the base includes between 10 and 150 pins.

11. A method according to claim 1 wherein the plastic is a copolymer plastic.

12. A method according to claim 11 wherein the plastic copolymer is substantially formed form dimethyl terephthalate (DMT), cyclohexanedimethanol (CHDM), and 2,2,4,4-tetramethyl-I,3 -cyclobutanediol (CBDO).

13. A method of forming a plastic beer drinking container comprising the steps of: injection molding a container form; and blowing the container form forcing a plurality of spaced apart pins into the base from a first side of the base to form corresponding raised nucleation sites on a second side of the base.

14. A method according to claim 1 or 11 wherein the molded container extends a predetermined height from the base terminating at an upper side wall, the molded container having a greatest diameter intermediate the base and upper side wall.

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