The present invention relates to a method of continuously producing filled disposable containers wherein a plastic in granular form is fed into an extruder from which a substantially tubular container material is extruded and caught by two symmetrical continuous conveyors located opposite each other and comprising mould-halves moving con¬ tinuously and synchronously, thereby forming moulds to shape said disposable containers. This method is suitable for packaging numerous types of substances, such as liquids in the pharmaceutical and food industries, pills and powder in the pharmaceutical industry and creams and ointments in the light chemicals industry.

Expedient packaging has become increasingly important in achieving more economic production. Transport, storage and otherwise dealing with empty packages constitute a considerable portion of the total production costs, both for the producer and the user of packages. The volume of the empty package consists to a great extent of air and reduces the freight capacity.

More and more producers are starting to make their own packages. Milk cartons are one example. Another is to manufacture containers from granular plastic, the containers being filled and sealed in integrated operations. Several of these operations follow each other chronologi¬ cally, thus extending the total production cycle. Optimum hygiene is of the utmost importance in the food and pharmaceutical industries, for instance, and the integration of manufacture and packing greatly improves the prospects in this respect. Furthermore, the manufacture can adjust production security to his own requirements. However, current processes entail a number of drawbacks, one being that manufacture and packaging cannot be carried out continuously.

US-A-3,913,299, for example, describes a method of manufacturing plastic containers by means of extrusion, filling and sealing. However, this necessitates heat treatment in three chambers in order to ensure an acceptable product. US-A-3,269,079 describes a method of producing a disposable container in which a tube is sealed at a lower end, filled and sealed at an upper end. This is not a continuous process either.

According to the present invention it has been found that disposable plastic containers filled with liquid, powder, granular or other solid products, can be produced using the method described in the introduction, characterised in that each disposable container produced is filled individually while in its mould and the container is thereafter sealed.

According to a preferred embodiment of the invention, moulding is effected with the aid of partial vacuum in the mould formed by the two halves. The pressure difference thus arising between the inside and the outside of the container material thus ensures that the plastic fills out the mould completely. Evacuation is preferably effected with the aid of a vacuum pump via narrow channels drilled in the mould.

According to one embodiment of the invention, an over-pressure is applied on the inside of the container material to further ensure that the container material completely fills out the mould.

According to another embodiment of the invention a tubular container material is extruded. This material is penetrated during the moulding process, and then filled through the opening formed.

According to another embodiment of the invention, a bubble is produced during the moulding process and penetration is effected in this bubble. This is advantageous when the container is subsequently sealed.

According to an alternative embodiment of the invention a tube provided with slits is extruded, thus eliminating the need for penetration.

Additional advantages and features of the present invention will be revealed in the following detailed description.

The container is filled through a nozzle moving synchronously with the conveyor carrying the mould-halves. The construction of the nozzles is dependent on the shape of the extruded container material, to be discussed below.

When filling is complete the nozzles are lifted from the containers and the mould-halves then opened. The finished packages continue along the same line and are separated either individually or in the form of multiple packages.

According to the invention, inert plastics such as polythene or poly- propene are preferably used for the containers. The inherent advantage of these plastics is that they contain no injurious components which can leak out into the contents being packaged. The containers can also be produced in several layers by means of co-extrusion with the object of improving the properties. The thickness of the extruded plastic is preferably 0.15-1.5 mm, depending on the size of the containe and its intended use. If desired, the wall thickness can be varied in each container by forming thicker or thinner portions during the extrusion. This can be achieved by extruding more plastic at certain portions of the nozzle, or by stretching the plastic to a varying extent during moulding.

The minimum inner dimension of the containers according to the invention is 5 mm and the maximum dimension is 400 mm. The cross section may vary and may be circular, oval, square, rectangular or polygonal. The length of the container may vary from 20 to 500 mm, the wall thickness from 0.10 to 2.0 mm, and the container may hold between 1 ml and 10 liter.

^• For special purposes an orifice, handle, transfer cannula or the like may attached by means of lamination through pre-heating, glueing or shrinkage against the plastic wall during moulding. The part to be attached can be pre-heated and the cooling effect of the mould-half be reduced in order to facilitate attachment. The mould-halves may ^• be designed so that a hanging means is stamped on the side opposite to the opening of the container.

The invention will be described in the following with reference to embodiments of an installation for performing the method according to the invention, with reference to the accompanying drawings in which

Fig. 1A - 1C show schematically an installation for continuously producing filled disposable containers in accordance with the present invention,

Fig.2A - 2B show schematically a cross section along the lines IIA - IIA and IIB - IIB in Figure 1 , and

Figure 3 shows schematically the design of a nozzle for tubular container material, provided with means for penetrating the container material during the mould process.

Figures 1A - 1C show schematically an installation for continuously producing containers in accordance with the present invention. The installation comprises an extruder for horizontal extrusion of a sub¬ stantially tubular container material 1. "Substantially" tubular shall include container material provided with slits which may be said to have V or U shaped profile. The extrude comprises a nozzle 2 of suitable dimension and form, with an outer portion 3 and an inner portion 4. The nozzle may be circular or oval, in which case the extruded tube can be cut outside the opening of the nozzle, or a V or U shaped profile may be produced.

Two symmetrical continuous conveyors 5A and 5B with mould-halves move synchronously, are combined at 6 and, forming a mould, continue along the line X - X. According to the present invention, the containers are moulded and filled in these moulds produced by the two mould-halves. The mould-halves are designed to give an aperture 7 through which the containers can be filled.

The mould-halves are evacuated so that a pressure difference arises between the inside and the outside of the container, the extruded material thus assuming the same shape as the mould. This occurs imme¬ diately the two halves have been combined.

Equipment 9A - 9B is provided to perforate the material joining the containers together in a continuous strip, or to separate them from each other, following sealing equipment, not shown in detail. A con¬ tinuous conveyor 12A is also provided for dosing the product, and

is located in the immediate vicinity of the continuous conveyors 5A, 5B and operates synchronously therewith. This superimposed conveyor 12A is designed to carry dosing equipment and units indicated at 13 for evacuation of air enclosed in the mould-halves. Another conveyor may be superimposed on the conveyor 5B, either having the same function or for applying a cap on the containers produced (not shown).

In the embodiment shown in Figure 1A, the conveyors 5A, 5B are driven by chains and linked with spindles such as the spindle 14. The conveyor 5A, 5B are driven by drive wheels 16A, 16B by means of suitable motors (now shown). The direction of rotation of the wheels is indicated by arrows 15A, 15B. The operational speed is adjusted to the capacity of the extruder.

Figures 2A and 2B show mould-halves before and after being combined to a mould. Channels 8 to evacuate air from the mould are form in these halves, their orifices opening into an upper space 20 in the dosing nozzle. The evacuated air flows along tubes 13 and 17 to a vacuum chamber 18 forming a part of the dosing equipment 12A, and on to a vacuum pump. The dosing nozzle 19 is shown before and after dosing, respectively, if a tube with slits is used as container material

Figure 3 shows a portion of the dosing equipment intended for insertion into the mould if the container material is tubular and must therefore be perforated to enable filling. This portion comprises a plug section 21 fitting an upper opening in the mould and provided with evacuation channels 22, 23 to produce a partial vacuum in the mould. A perforation cannula 24 with a sharp, inclined edge 25 is provided centrally in the plug to cut an opening in the container material. According to an advantageous embodiment, the edge section 25 of the perforation cannula 24 is not sharp and thus leaves behind a "hinge" or lid for the part punched out. A filling or dosing cannula 27 is sheathed in the perforation cannula and is lowered into the container (not shown) after perforation. Perforation is preferably effected during moulding by the perforation cannula being lowered into the mould imme¬ diately the plug portion has been applied, so that while the container material is filling the mould, it is pressed against the cannula and thus perforated. According to an advantageous embodiment, air or some other gaseous medium may be supplied in a gap 28 between the two cannulae to further improve moulding.

Naturally this dosing equipment be provided, like that in Figures 2A and 2B, with a space so that a raised bubble is formed in the container.

Perforation is then effected in the bubble. Subsequent sealing of the container, suitably effected by welding, is thus facilitated.

According to another advantageous embodiment, this space is circular and provided with screw threading around the bubble, thus enabling the opening to be closed by a screw lid.

Modifications and further developments are of course possible within the scope of the present invention. One such development is the produc- tion of two or more containers joined together, i.e. a container with several compartments, enabling the contents to be mixed without, for instance, jeopardizing its sterility. In this case the containers can be made in different sizes, alternate moulds being made a different size. The contents in such cases is generally a liquid, but might also be a powder or the like which is to be mixed with liquid. In this case the containers are provided with a means for mixing the contents without the normal opening of the container having to be opened, thus guaranteeing that the contents remains sterile.

Several dosing systems are of course necessary for the latter case. According to one embodiment, one of the containers is left empty and is then filled outside the continuous system. Alternatively a second filling system can be connected in synchronization with the first and reversed with respect thereto.