DE2850231A1 - CONTAINER FOR BEVERAGES CONTAINING CARBON - Google Patents

Description

The invention relates to containers for carbonated beverages. The containers are for small quantities of beverages intended for individual consumption in contrast to large containers or storage tanks for large quantities of beverages that are dispensed or in quantities for individual consumption should be subdivided.

Large quantities of carbonated drinks, for example Beer or low-alcohol or non-alcoholic beverages are sold in containers around the world; conventionally exist such containers made of glass because of their great strength and good gas tightness to prevent loss the carbon dioxide of the drink before opening the container. The glass containers have the disadvantage that they are easily broken, not easy to remove and that the glass containers occupy a large space. In addition, the empty glass container can easily turn into dangerous or even deadly weapons will.

Because of the disadvantages associated with the use of glass, metal containers or cans have been used for carbonated beverages developed and these cans consist essentially of a metal sleeve to which end parts made of metal are tight are flanged; one of the end portions has a facility for easy opening so that the contents of the can are accessible will. These cans have been introduced so well that there are currently about the same number of cans as there are glass containers in total World are in use.

These cans made of metal also have disadvantages: For example they can also be used as thrown weapons, they are difficult to dispose of and they are expensive.

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Another type of known container for storing carbonated Beverages are blow molded plastic containers. These containers are less dangerous as thrown weapons, however they must be made relatively thick-walled and this makes the production expensive, since expensive manufacturing facilities are necessary and only a relatively low production speed is possible.

For this reason, the decision was made as early as 1969, to provide a carbonated beverage container made from extruded plastic sheet material by conventional methods is generated by thermal deformation.

The advantages obtainable from such a container are considerable. First, the container is made of a relatively thin material with a thickness that of the metal shell of a made of metal is comparable, making the container easier to dispose of and because of its smaller size Empty weights are less dangerous and, secondly, they can be produced easily, cheaply and quickly.

One of the first attempts to thermoform a container from an extruded plastic sheet was a Laminate of a sheet of polystyrene and a layer of high barrier Acrylonitrile polymer in the form of a container, reshaped by the action of heat using a conventional thermoforming process. A high barrier acrylonitrile polymer was used, namely Barex with a thickness of 76.2 µm (= 0.003 ") and that high-impact polystyrene had a thickness of 1.14 mm (= 0.045 "). Basically, the Barex layer gave the gas barrier property of the container, while the polystyrene outer wall gave the container its strength. After manufacture, the container was sealed in that a metal lid with means for easy opening on an upper peripheral flange the plastic container has been flared or rolled up.

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Experiments with containers made in this way, those with carbonated Drinks were filled and then sealed in the manner indicated, presented a number of technical problems. First, hairline cracks developed in some containers as a result of the sealing with the lid, the lack of strength of the plastic material used to manufacture the containers, in particular the polystyrene. Second, it surrendered In the course of time, the beverage in some containers has become carbonated, which can be attributed to imperfections in the barrier layer that could hardly be seen with the naked eye. These problems could be solved by the Strength of both the barrier layer and the impact resistant polystyrene is increased, but increasing the strength goes against the goal of a satisfactory thermoplastic Produce containers at a reasonable cost.

Originally, the underside of the container should be shaped like a hemisphere, so that the container is resistant against creep because it was assumed to be a hemispherical shape is most conducive to the underside of strength. It was intended to keep the inner container under cooling with it Filling carbonated beverage, sealing it and then placing it in an outer container or bowl, with which the container comes into frictional engagement in that the chilled beverage is warmed to ambient temperature and so that about carbon dioxide gas is released from the solution, so that the internal pressure in the container rises and the inner container up to in the frictional engagement with the outer container is stretched. There were packs made in this way, the containers and Contained servings or cups and they appeared from the market to be accepted; the ones with the hairline cracks and the ones with the escape of the carbonic acid gas related problems mentioned were not completely solved, even if the inner containers satisfactory by friction with the external

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Shells came into engagement until the inner containers were opened, allowing the internal pressure to escape and the Containers could be separated from the shells. The bowls could then be used as drinking vessels.

The outer shells and inner containers were made of high impact strength Made of polystyrene; the quadrupling of the oil price in the years 1973 to 1975 lowered the cost of the Packaging become too large and a "one-piece" container was immediately sought, which basically consists of one Plastic container and a metal lid. In pursuing this goal, it turned out that the hemispherical Design of the container bottom had to be modified so that the container can stand freely. Even the first manufactured "one-piece" containers consisted of laminates, which were constructed from impact-resistant polystyrene and a barrier layer, but this container also had the disadvantages of Hairline cracks and carbon dioxide loss. In the next stage of development a "one-piece" container was investigated, the consisted only of Barex of adequate strength and it turned out that the gas tightness was ok as Barex a much better gas barrier property than the high impact resistant one Owns polystyrene.

The exclusive use of Barex again resulted in its own problems, since Barex "creeps" under load and accordingly the filled and sealed Barex containers bulge unacceptably in the wall area over time and / or the bottom part deformed in such a way that stability could no longer be achieved. There were either containers that are standing could, but wiggled back and forth between different positions when they were nudged, or it surrendered Containers that could no longer stand free at all.

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There have been developments in the construction of the bottom part of the Barex containers made to prevent deformation of the bottom part in the manner mentioned and in a market test 25,000 one-piece Barex containers filled with beer were carried out. Because of the beer filling it was necessary that the container after filling and sealing had to be pasteurized. Since heating must be carried out during pasteurization and consequently More carbon dioxide goes out of solution in the drink, which increases the internal pressure in the container during pasteurization increased, it was necessary for the pasteurization to be carried out after filling and sealing with containers inserted in metal jackets became.

The market test with the 25,000 containers mentioned was * found to be satisfactory from the customer side, but the containers themselves were not completely satisfactory from the manufacturing side. A small proportion of the containers suffered cracks or developed hairline cracks on the top during sealing and the burst strength of the containers was not great enough that some containers burst under an internal overpressure of only 3.8 bar (= 55 psi). Of course, the rupture problem could be eliminated by reinforcing the container wall, but this would make the problem of tearing during sealing even worse, since the container flange and the lid flange are crimped together during the sealing process and the container must have sufficient flexibility so that the crimping without crimping Appearance of cracks is going on.

It was made with two other types of a polymer-containing acrylonitrile experimented, namely the material Cycopac 920 and, Cycopac 930 from Borg Warner; these materials proved proved to be less resistant to the occurrence of cracks during sealing than the Barex material, and how the Barex containers also had to be made from the materials mentioned

manufactured containers are held in metal outer molds during pasteurization.

Despite these difficulties, the usefulness of thermoformed containers for carbonated beverages has continued to expand believed possible and a material was investigated which is not usually thermoformed from extruded sheets is, namely polyester. It has been known that polyester has been used as a film material for flexible packages and in the investigation of the gas barrier properties showed encouraging results. The experiments carried out concerned two mainly used polyester materials, namely polyethylene terephthalate and polybutylene terephthalate. Polyethylene terephthalate showed the better gas barrier properties and it was made with a number of different types of commercially available polyester experimented that are not actually recommended as sheet extrusion materials; it is the the following materials:

1. Vestadur 2271 from Hüls,

2. APV 4000 from Hoechst,

3. types of polyester with low viscosity, type 42 and type 49 from Hoechst,

4. Polyester types type S and type 0 from I.C.I.,

5. Polyester type A 200 from Akzo, in particular that of Akzo with A04 / 102/307 designated varieties.

Vestadur 2271 was satisfactorily extruded in sheet form, however, the material did not flow evenly enough during the subsequent heat transformation into containers, to achieve satisfactory results.

The APV 4000 material performed satisfactorily during extrusion and heat forming, but Hoechst the production of this material ceased. The varieties 42

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and 49 had unsatisfactory extrusion properties on.

The polyester types S and O from I.C.I. Applicants did not extrude satisfactorily, however I.C.I. provided some extruded sheet material of types S and O, which are used in the subsequent heat forming Gave containers unsatisfactory because of the occurrence of cracks.

Akzo's A04 / 102/307 material was found to be good extrudable and satisfactorily thermoformable; a number of containers were made from it, filled and sealed and proved encouraging when tested.

The analysis and testing of the various materials examined showed that as a raw material for carbonated beverage containers thermoformed from sheet material, highly viscous polyester material with a high molecular weight is extremely suitable.

Accordingly, the present invention provides a plastic container Created for carbonated beverages, made from a high-viscosity polyester material extruded in sheet form is thermoformed with a high molecular weight and is designed to have a flanged or rolled-on metal lid provided with a device for easy opening can be closed.

The invention also includes the use of such a container closed with such a metal lid as Liquid packaging.

By using a high-viscosity polyester material with a high molecular weight, the following advantages are achieved:

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a) There is a material that can be satisfactorily extruded,

b) the material can be satisfactorily thermoformed,

c) the material allows a metal lid to be rolled up or flared without the formation of hairline cracks,

d) the material creeps very little, if at all, after filling the carbonated beverage and sealing,

e) the material has good gas barrier properties and

f) the MaLerial has good strength properties, so that results in a high burst resistance;

all of these advantages are achieved with a material thickness equivalent to that of conventional thermoformed containers.

Such containers are extremely suitable for holding carbonated beverages that do not need to be pasteurized; However, even when looking at containers made of such material that are filled, sealed and then pasteurized, the resistance of the thermoformed container at elevated temperature can be increased by causing the relatively amorphous polyester to partially crystallize by causing the relatively amorphous sheet material is thermoformed in a tool brought ^{to a temperature between 140 0} C and 180 ^{0 C by oil or in a similar manner.} The temperature at which the containers produced in this way deteriorate is raised from about 75 C to more than 200 ° C, which increases the possibility of pasteurization and sterilization of liquids in the crystallized or partially crystallized containers.

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With the characteristics of "high viscosity and high." Molecular weight "the relationship is established with a polyester material, its average molecular weight ranges from 37,000 to 55,000 inclusive.

Preferably the container is generally frustoconical in shape and the top diameter to depth ratio is in the range from 4: 8 up to and including 6: 8.

In addition, a stacking ring is formed at the top of the container and the height of the stacking ring is with respect to FIG half the cone-tip angle of the container and the material thickness designed so that the containers fit into each other before filling can be stacked and mechanically and precisely separated from one another.

The containers can be held with a flanged or rolled up Metal cover can be closed by means of a plastic cover, as described, for example, in GB-PS 1,477,828 is and this plastic cover can either also be flanged or otherwise brought into tight connection.

During the thermoforming of the container, the sheet material is preferably in a concentrically surrounding the mold cavity annular area clamped and the annular area has an inner diameter that is at least 1.5 times Has the value of the upper diameter of the mold cavity and preferably in the range of 1.5 to 2 times this value lies. This clamping of the material in place creates a flange on the top of the container formed between the top of the mold cavity and the clamped area. This flange is used for flanging or Roll the metal lid to the top of the container.

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With containers in which carbonated orange drink with a carbonic acid content of 2.5 times the volume value was filled and stored at a temperature of 30 ° C, creep tests were carried out which showed that the containers were not harmful for a period of at least 2 months Crawling showed. Similar tests at 35 C showed that a se]
did not occur for 48 hours.

at 35 C showed that there was harmful creep within

The bursting ability was tested by the internal pressure by. Injection of compressed air at ambient temperature increased became; it was found that the containers withstood a pressure of 7.6 to 8.3 bar (= 110 to 120 psi) to burst and that the lid is blown off sooner than the container comes to burst.

Because of the advantage described that the container in the If the flaring or sealing does not show any cracks, there may be a greater tolerance with regard to the thickness deviation of the flange section to be flanged at the top of the container. As a result of the fact that the material can creep less the design of the container bottom can be simplified.

The invention also provides a method of making containers which consists in making the highly viscous polyester material high molecular weight extruded in sheet form and then the containers are thermoformed from the sheet.

The invention is illustrated below with reference to the drawing, for example explained in more detail; in the drawing shows:

Figure 1 is a side view of a container thermoformed from the extruded sheet material described ,

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FIG. 2 is a perspective view of the container from FIG. 1 viewed obliquely from below,

Fig. 3. A plan view of the container according to Fig. 1 and Fig. 2,

Fig. 4 is a sectional view of the upper edge and the lower portion of the container according to Figs. 1 to 3 on an enlarged scale,

FIGS. 5, 6 and 7 representations corresponding to FIG. 1,2 and 3 a container closed by a metal lid, and

Figures 8 and 9. two intermediate stages in flanging the metal lid to the top of the container.

In the drawing, a container is shown, which is preferably made of polyethylene terephthalate. It is an embodiment shown which is suitable for storing carbonated beverages, especially soft drinks that are not need to be pasteurized.

The container shown in Figures 1 to 3 is formed by conventional thermoforming processes made of extruded sheet material, preferably polyethylene terephthalate. For example, the container by deep drawing, blow molding or a combination of these processes with or without an internal mold will. The container is generally frustoconical in shape Wall 10, at the top of which a stacking ring 12 and an outwardly protruding fastening flange 14 is formed on the upper edge thereof. The bottom portion 16 of the container is designed so that six downwardly protruding, sepal-like feet are formed, as shown in the plan view

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Fig. 3 can be seen. According to the illustration in FIG. 4, these feet 18 are essentially of a spherical shape Lower surface 20 in front. The feet 18 can either be viewed as protruding from the section 20, or the feet can be said to be separated from one another by curved strips leading to a central region 22 to lead. It should be noted that the central region of the curved strips is stronger than the rest of these strips and also stronger than the container wall is otherwise. This is due to the fact that the central area during the thermoforming of the container is not stretched and also from the fact that the central area is on a relatively cold section in the bottom area of the mold cavity. In any case, it is The structure shown designed so that a deformation of the floor area is so far resisted that the area 22 bulges further downwards than the areas of the feet 18 on which the container stands up. The bottom section can of course also be interpreted in a different way, if only the principle just explained is observed. It is However, it is necessary that the floor area has certain structural properties that are necessary from the point of view of strength because the container is intended to hold carbonated beverages in particular and therefore before consumption the contents of the container is subjected to internal pressure.

In Fig. 5, 6 and 7, the container according to Fig. 1, 2 and 3 is shown, after which a metal cover 24 of conventional construction has been closed with a tear ring 26. If on that Tear ring 26 is pulled, the teardrop-shaped section 28 is torn open and that contained in the container Drink can be taken out. Metal lids 24 with tear rings 26 and tear areas 28 are common in the beverage industry known.

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The container is filled with the carbonated beverage before the lid 24 is placed on the top of the container will. Usually the drinks are chilled when they are filled and the lid is put on as quickly as possible after the filling process to keep the carbonic acid gas in the drink in solution. If the locked one The container with its contents and the closure lid 24 is transported or stored before the contents of the container are used up, the temperature of the contents will rise to ambient temperature and the internal pressure in the container will rise accordingly raise. The level of the internal pressure depends on the ambient temperature in which the sealed container is located; According to the regulations in force in Great Britain, the containers should have an internal overpressure of 7.6 to 8.3 bar (= 110 to 120 psi). Containers that met this requirement could be made of a polyester material of the type described and a thickness of 1.4 mm (= 0.055 ") when a carbonated orange beverage filling is made with a Carbon dioxide addition of 2.5 times the volume and a seal with a metal lid is required. Furthermore Such containers have good gas barrier properties that a result in only a slight loss of carbon dioxide during storage for 6 months.

According to Fig. 8, the metal cover 24 has in the manufactured Way a flange 30, and this is by curling or flanging with a flange 14 on the top edge of the container tied together. FIG. 8 shows the state when the metal cover is in place and FIG. 9 shows the state after it has taken place Flanging in which there is a good seal between the metal ceiling! and container edge has set. The flange 30 according to FIG. 8 contacts the flange 14 without an intermediate layer; it may be necessary or be advantageous to insert a ring of sealing material between the flanges 14 and 30 before crimping, and it

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It may also be advantageous to crimp the crimped flanges as shown by arrows X-X in FIG is.

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Claims (8)

Claims f 1.! Plastic containers for carbonated beverages, V / characterized in that the container by Thermoforming made from an extruded sheet of high viscosity, high molecular weight polyester material and for closing with an attached by edge rollers, provided with an easy-to-open closure Metal lid is designed. 2. Container according to claim 1, characterized in that that the container material is heated to a temperature between 140 ° C and 180 ° C by forming in a Thermoforming form is partially crystallized. & 0-9823 / 061 « MANlTZ · FINSTERWALD · HEYN · MORGAN ■ 8000 MUNICH 22 · ROBERT-KOCH-STRASSE 1 · TEL. (0B9) 2242 11 TELEX 05-29672 PATMF ORiOlNAL INSPECTED 3. A container according to claim 1 or 2, characterized in that the container is generally frustoconical with a top diameter to depth ratio in the range of 4: 8 to 6: 8 inclusive. 4. Container according to one of claims 1 to 3, characterized in that at the upper end of the container a stacking ring is formed, the height of which in relation to half the cone-tip angle of the container and the Material thickness is set so that the containers can be stacked one inside the other and mechanically before filling are exactly separable. 5. Container according to one of the preceding claims, characterized characterized in that the container is concentric by clamping the sheet material in a mold cavity resulting annular area is held and that the annular area has an inner diameter of at least 1.5 times the size of the upper diameter of the mold cavity, preferably in the range from 1.5 to 2 times of the top diameter of the mold cavity. 6. Container according to one of the preceding claims, characterized characterized in that the container is made of polyethylene terephthalate. 7. Use of a container according to one of claims 1 to 6 for a beverage packaging with a metal closure lid with facility for easy opening. 8. A method for the production of containers according to any one of claims 1 to 6, characterized in that that high molecular weight, high viscosity polyester material is extruded in sheet form and then the Containers are made from the sheet material by thermoforming. 909823/0616