The present invention finds its application in the food industry for packaging of the beverages, particularly gaseous beverages .

Packaging of the beverages is one of the main problems food industry is facing. There are three main types of the packages: made of glass, cardboard and plastics, e.g. PET type. The packages made of glass despite their unquestionable advantages such as: being ecological and insolubility have also disadvantages such as breakability and high weight. Packages made of cardboard are free from these disadvantages, however due to low rigidity are not suitable for packaging of the gaseous beverages, moreover for the sake of complex structure are difficult to recycle. It seems that least of disadvantages have packages PET type, because they are non- breakable, lightweight and sufficiently resistant to effect of pressure of gaseous beverages. Appropriate utilisation and sorting allow reusing of used packages PET type. In the case of gaseous beverages or hermetically packaged leakproof closure is required. It is provided by screwed closures or bail closures, which are characterised by quick closing and opening, and high leakproofness . The European patent application EP1129958 discloses bottle PET type that is closed with the bail closure. High stresses, to which walls of the bottle have to oppose to, made authors of mentioned application to produce bottles with as thick walls as glass bottles have. This operation has unfavourably affected on the weight of the bottles, their appearance and costs of production. Polish patent application PL363595 discloses preform for manufacture of plastics bottles PET type comprising a body (4) with arcwise convex bottom, characterised in that the body (4) has a shape of opened from the top cone, that is directed with the rounded vertex downward. The body (4) passages from the top to cylindrical crowning (2) , upper part of which forms bent to the outside ring-shaped flange (3) ended with shaped contour. Preferably, inner surface flare angle (a) of the body (4) with the shape opened from the top cone is larger than the outer surface flare angle (β) of the body (4) , walls thickness (g2) of the cylindrical crowning (2) is lesser than thickness (g3) of the bottom. This type of preform is characterised by complexity of the structure and little universality and disposability of the closure. Similar structure has preform disclosed in polish patent application PL371237.

Concerning the above there is a need for the manufacture of such preform, which enables producing of the bottle PET type suitable to store gaseous beverages closed with bail closure. Unexpectedly the present problem is solved by the present invention.

The present invention refers to the preform of container made of plastics closed with bail closure, particularly for the food products, comprising a body closed at one side for blow moulding during formation of the container, and opened at the other side and ended with a supporting ring, below which there are symmetrically disposed notches, which are arranged over lower ring, characterised in that the angle between tangent to an upper edges of the supporting ring and tangent to a side edges of the supporting ring is ranged from 10° to 40°, and the ratio of the sealing ring height to its width is ranged from 0,13 to 6,5, while maximal height of the sealing ring is 1,5 mm and minimal height is 0,2 mm and maximal width is 1,3 mm and minimal width is 0,2 mm. Equally preferably, the preform according to the invention is characterised in that said angle is in the range from 18° to 22° and the ratio between width of the sealing ring to its height is 0,83, and preferably width is 0,5 mm and height is 0 , 6 mm .

The second object of the present invention is the process for the production of plastics bottles closed with bail closure, characterised in that it comprises the steps of:

a) conditioning of a raw material;

b) plasticization of the raw material;

c) injection of the molten granulate to the mould;

d) moulding of the material into preform having angle a between tangent to the upper edges of the supporting ring and tangent to the side edges of the supporting ring ranged from 10° to 40°, and the ratio of the inner ring height to its width is ranged from 0,13 to 6,5, while maximal height is 1,5 mm and minimal height is 0,2 mm, and maximal width is 1,3 mm and minimal width is 0,2 mm;

e) cooling of the preform;

f) blow moulding of the preform into bottles.

The third object of the present invention is a bottle obtainable by process definied in the invention.

Thus, designed preform and formed on its basis bottle are characterised by high resistance to high pressure. New form of the preform guarantees that the bottle formed on the basis of this preform is characterised by the leakproofness to 10 bars. Specific structure further provides high resistance to shocks and displacement of the bottles formed on the basis of the present preform. Suitably sloped supporting ring carries the stopper of the bail closure deposited on the borders thus preventing to tilting, deviating that stopper during side thrust at the time of transportation. When the package is closed, the stopper of the bail closure, in phase I is arranged on the sealing ring. In a very short time, deposited stopper of the bail closure due to driving into rubber of the stopper resting on the inner ring, is lowering to further deposit with its borders on the supporting ring, further sealing the closure. The arrangement of the two rings results in bottles with bail closure with durable, stable leakproofness , while the preforms are characterised by lower weight in comparison to the previously known preforms. Examples of the embodiments according to the present invention are shown in the appended drawings, in which fig. 1 shows cross-section of the preform neck, fig 2 shows isometric view of the preform neck, fig 3 shows in details cross-section of the sealing ring, fig. 4 shows the perform and fig. 5 and 6 shows bottle obtainable by process definied in presented invention.

Example 1

The preform for blow moulding of bottles consists of cylindrical body 1 at one side closed to blow moulding, and opened at the other side, which forms the neck of the next bottle. At opened end, there is the supporting ring 2 that is sloped at angle 20° to tangent to the borders of the opened end of the body 1. Closer to the axis of the cylinder is arranged the sealing ring 5 with height 0,5 mm and width 0,6 mm. Below, there are notches 4, which are positioned above the lower ring 3.

Example 2

There is provided primary granulate PET, then it is dried in the dryers and plasticized by using heated extruder with warm. Subsequently, the molten granulate is injected to the mould by the system of hot channels provided in the mould by using injection seats. Then, there is formed a material for the preform, which is cooled with the cooling channels. Afterwards, the material is transported to the machine, in which by blowing-out with compressed air, after previous heating of the preform, is shaped into blown forms of the bottle. The bottle maintains identical neck like the preform. Heating and blow moulding with compressed air is subjected only to a part of the preform that is below the lower flange.

Example 3

Leakage test after completing the carbonated beverages at a pressure of 10 bar showed sufficient tightness. Obtained a bottle of the present invention is shown in Figure 5 and 6.