WO2006054089A1

WO2006054089A1 - Method and arrangement for forming a container having an internal wall and container having an internal wall

Info

Publication number: WO2006054089A1
Application number: PCT/GB2005/004441
Authority: WO
Inventors: David Alan Gilbert White; Paul Dean; Steve Davis
Original assignee: Polimoon Packaging Limited
Priority date: 2004-11-17
Filing date: 2005-11-17
Publication date: 2006-05-26
Also published as: GB2420311A; EP1824658A1; GB0425337D0

Abstract

A container (100) comprising at least two container regions (110, 120), the container (100) being formed through the use of a pin (20) comprising a slot (25) in a blown extrusion moulding process. Plastic material formed into the slot (25) is used to form the division between the regions (110, 120) of the container (100).

Description

METHOD AND ARRANGEMENT FOR FORMING A CONTAINER HAVING AN INTERNAL WALL AND CONTAINER HAVING AN INTERNAL WALL

The present invention relates to a container and in particular to a container comprising two or more cavities.

It is well known to form an aggregate container having two compartments from two inter-engaging container components (see for example our earlier application GB 2 388 097). Such containers are of use for storing two different materials that need to be mixed prior to use but cannot be stored together for a prolonged period of time. Whilst these aggregate containers are useful, there is a disadvantage in having to manufacture the two container components and then assembling them to form the aggregate container.

According to a first aspect of the present invention there is provided a method of forming a container, the method comprising the steps of: forming an assembly comprising a pin received within a die, the pin comprising a slot extending partially along the pin; inserting molten plastics material into the aperture formed between the pin and the die, the molten plastics material being inserted under pressure such that a portion of the plastics material is impelled into the slot of the pin; causing the plastics material to conform to the shape of the die; transferring the plastic material from the die to a mould; and applying a source of pressurised gas to a portion of the plastic material to form a container, wherein the plastics material impelled into the slot of the pin forms a wall within the container to form two or more separate container regions.

According to a second aspect of the present invention there is provided a container comprising an internal wall, the internal wall forming at least two separate container regions within the container.

Preferably there are two container regions. Where there are more than two container regions, the upper limit to the total number will be determined by the size of the container (larger containers becoming necessary if several regions are required) and the area of the top of the container as this surface must accommodate the required number of apertures.

The container regions may be of different volumes or of similar volumes. For instance, there may be two regions of substantially equal volume, or a first large region and a second smaller region. This embodiment would be of use where one of the components to be stored within the container is required in a smaller volume than the second. Alternatively, there may be three or more container regions of equal or differing sizes.

In preferred embodiments each container region has at least one aperture to facilitate filling of the bottle and dispensing therefrom. Preferably, there will be two apertures, each of the apertures being associated with each of two separate container regions. The container may be made from any material which is both extrudable and plastically deformable. However, it is preferred that the container be formed from a plastics material, for example polypropylene, polyethylene or polyvinylchloride .

Dependent upon the relative configuration of the pin and die, and shape of the consequent gap between the pin and the die; the parison may be annular, ellipsoid or oval. Typically, the gap between the pin and die will be annular, resulting in the production of an annular parison.

The container may have any shape into which it is possible to make a blow mould. In particular, the container may have, for example, different cross-sectional configurations (e.g. round, square, circular, elliptical, non-uniform); a height which is either greater or smaller than the width and/or depth; tapering to produce cones, pyramids, tetrahedrons or frusto-conical configurations; stepping between different cross-sectional areas; or rotation of the cross-section smoothly around the central vertical axis to produce a 'twisted' appearance to the outer surface of the container. According to a third aspect of the present invention there is provided an arrangement for forming a container the arrangement comprising a pin located within a die, the pin comprising a slot extending into the pin and partially along the height of the pin; and the pin being received within the die such that the pin is separated from the die by a second annular gap.

The slot in the pin may be such that a single internal wall will form in the parison. Where a single internal wall is to be formed, the slot extends across the width of a lower portion of the pin so that the pin comprises a linear slot extending partially along the pin and parallel to the major axis of the pin and the die. The pin may comprise a central member received within a peripheral member, the central member of the pin comprising a slot extending across the width of the pin. Alternatively, the central member and the peripheral member may be a single component.

Alternatively, there may be more than one slot arranged to produce three or more container regions in series. Where this is the case, it is preferred, but not essential, that the walls are substantially parallel. As a further alternative, the slot or slots may be arranged so that they do not extend across the entire width of the pin, but meet in the interior of the pin to form a parison incorporating segments which may be equally or differently sized. Accordingly, there may be any number of segments, providing the container is large enough to accommodate these. Preferably, there will be between two and six container regions, more preferably two or three, most preferably two container regions.

In an alternative aspect of the invention, there is provided a method of forming a container, the method comprising the steps of: forming an assembly comprising a pin received within a die, the pin comprising a linear slot extending partially along the pin and parallel to the major axis of the pin and the die; inserting molten plastics material into the aperture formed between the pin and the die, the molten plastics material being inserted under pressure such that a portion of the plastics material is impelled into the slot of the pin; causing the plastics material to conform to the shape of the die; transferring the plastic material from the die to a mould; and applying a source of pressurised gas to a portion of the plastic material to form a container, wherein the plastics material impelled into the slot of the pin forms a wall within the container to form two separate container regions.

According to a further aspect of the present invention there is provided a container comprising an internal wall, the internal wall forming two separate container regions within the container.

According to a yet further aspect of the present invention there is provided an arrangement for forming a container the arrangement comprising a pin located within a die, the pin comprising a central member received within a peripheral member, the central member of the pin comprising a slot extending across the width of the pin and partially along the height of the pin; and the pin being received within the die such that the pin is separated from the die by a second annular gap.

The invention will now be described, by way of example only, with reference to the following figures in which:

Figure 1 shows a first view of a schematic depiction of an assembly for use in accordance with the present invention;

Figure 2 shows a second view of a schematic depiction of an assembly for use in accordance with, the present invention, the second view being perpendicular to the first view shown in Figure 1 ;

Figures 3 a to 3e show a schematic depiction of an assembly for use in accordance with the present invention; the views being through sections A-A to E- E of Figure 2; and

Figures 4a to 4d shows a schematic depiction of a container made according to the method of the present invention. For avoidance of doubt it should be noted that in this specification reference to 'up', 'down', 'upper', 'lower', 'vertical', 'horizontal', 'top', 'bottom' and related terms refers to the orientation that the components of the apparatus adopt when in normal use, as they are shown in the figures.

Figure 1 shows a first view of a schematic depiction of an assembly 10 for use in accordance with the present invention. The assembly 10 comprises pin 20 which is received within die 30. Pin 20 comprises a central member 22 which is received centrally within annular member 24. The central member 22 comprises a slot 25 that extends across the width of the lower portion of the central member 22 of the pin 20, but only for a portion of the height of the central member 22. The pin 20 further comprises first and second passages 27, 28 that extend along the length of the central member 22. The first and second passages 27, 28 are located on either side of the slot 25. The die 30 comprises an annular member 32 and the pin 20 is received within the die 30 such that there is an annular gap 33 between the annular member 24 of the pin 20 and the annular member 32 of the die 30. Both the pin 20 and die 30 are metallic. In this example the parison 45 is polypropylene.

In an alternative embodiment (shown in Figures 3a - 3e), useful where any number of container regions whether two or more are formed, the pin 20 is of one piece construction with first and second passages 27, 28 passing through and extending along the length of the pin 20. In this embodiment, the central member

22 and annular member 24 are one component (the 'pin' 20) and the first and second passages 27, 28 are aligned with each other in the diametrical plane of the pin 20.

The slot 25 comprises, at the top of the pin 20, two graduated slots 31 at diametrically opposing points around the annular surface of pin 20. The slots 31 become increasingly elongate as shown in Figure 2 and Figures 3 a - 3e, from the top to the bottom along the length of the pin 20. At the distance of approximately one sixth the total length of the pin 20 from the bottom of the pin 20, the slots 31 meet to form a single slot 25. From this point to the bottom of the pin 20, the slot 25 extends across the width of the pin 20 allowing the formation of a single bisecting internal wall 130 in the parison 45 (this internal wall 130 becoming the internal wall 130 of the container 100 upon moulding). The extruded polypropylene is forced into the slot 25 as it passes along the pin 20 from the top to the bottom of the die 30. Where the slot 25 extends across the entire width of the pin 20, the extruded polypropylene meets and forms the internal wall of the parison 130. Figures 3a - 3e illustrate the graduation of the slot 25 from the top to the bottom of the pin 20 and the formation of the internal wall 130 of the parison 45 therein.

The mould is positioned, in this embodiment, below the die 30 so that the extruded parison 45 can pass from the die 30 into the mould for subsequent blow moulding.

Accordingly, the assembly is used in a modified extrusion process, wherein molten plastic is extruded through the assembly 10. The molten plastic is forced under pressure into the annular gap 33 between pin 20 and die 30 from the top of the pin 20 and die 30 arrangement to produce a tube 40 that adopts the shape of the aperture formed between the pin 20 and the die 30. This rube 40 is then extruded out of the bottom of the pin 20 and die 30 arrangement and transferred into a mould. Pressurised gas is used to force the molten plastics material against the interior of the mould, such that the plastics material takes on the shape of the mould.

In an alternative embodiment of the invention, pressurised gas may be passed through first and second passages 27, 28 to reduce the possibility that the tube 40 collapses or separates from the wall of the die 30. Passage 27 supplies air into a space on a first side of the internal wall 130 of the parison 45 and a second passage 28 supplies air into a space on a second side of the internal wall 130 of the parison 45.

Once the tube 40 is formed then it is transferred to the mould and the plastics material is blow moulded as described above. In use, molten plastics material (e.g. polypropylene) is extruded into the annular gap 33, between the pin 20 and the annular member 32 of the die 30. It has been found that due to the viscosity of the molten polymer, the polymer mainly remains within the annular gap 33 and a relatively small amount flows into the slot 25 in the central member 22. If a container 100 comprising a continuous internal wall 130 is to be formed then it is imperative that the slot 25 in the pin 20 is filled with a polymer material.

It has been found that the slot 25 can be suitably filled by reducing the gap 35 on the end face, so that the pressure typically exerted on the plastics material by the extrusion process forces a portion of the plastics material into the slot 25 such that the slot 25 is filled. This causes a tube 40 to be formed having a membrane 130 across its middle.

The extrusion process is then continued so that the parison 45 flows downwards into the mould, which is in fluid engagement with the die 30, thus transferring the plastics material from the die 30 to the mould.

The required length of parison 45 is severed from the continuous extrusion using a knife (not shown), the length is greater than the length of the mould cavity to ensure that when the mould is closed the bottom of the mould grips the distal end of the parison 45, sealing this end so that blow moulding forms a sealed base of the container 100. Similarly, the proximal end of the parison 45 is gripped by the upper edge of the mould cavity, so that an upper surface of the container 100 will be formed. However, at the upper edge of the mould, gaps occur in the sealed parison 45 at the portion of the mould that forms the apertures 115 of the container

100. This ensures a clear passageway into the retained parison 45 for a twin blow pin assembly (not shown) to enter. A container 100 can then be formed from this parison 45 using conventional blown extrusion moulding techniques.

The size of the gap 35 can be determined through experimentation and may vary with the material being used and the weight and the size of the container 100 to be formed. It has been found that the cross-sectional area of the gap 35 should be substantially equal to that of the slot 25.

Figure 2 shows a second view of a schematic depiction of an assembly for use in accordance with the present invention, the second view being perpendicular to the first view, shown in Figure 1. Figure 2 shows in particular a cross-section through the middle of the central member 22 of the pin 20. This central member 22 of the pin 20, which defines the shape of the slot 25 formed within the pin 20, has a V- shape 26.

Figure 4 shows a schematic depiction of a container 100 made according to the method of the present invention, as described above. Figure 4a shows a front view of the container 100. Figure 4b shows a side view of the container 100. Figure 4c shows a top view of the container 100 and Figure 4d shows an underside view of the container 100. The container 100 comprises two container regions 110 and 120 which are separated by internal wall 130. Each of the container regions HO₅ 120 has an associated aperture 115, 125 through which the contents of each container region 110, 120 may be dispensed, hi use, a cap will be received on top of the container 100 that may allow the contents of each container region 110, 120 to be mixed together as they are dispensed from the container 100 or alternatively allows the contents to be dispensed separately.

Figure 4d shows that the two container regions 110, 120 are of substantially equal size, although it will be readily understood that the relative size of each container portion 110, 120 may be varied. Figure 4d also shows that internal wall 130 takes the form of a straight line, essentially parallel to one of the axes of the container 100. It will be understood that the internal wall 130 may be provided at a different angle.

Figures 4a - 4d show that the container 100 (formed by the assembly of Figures 1 and 2) has a cross-section that is substantially rectangular with rounded-corners. It will be understood that other cross-sections may be used, for example square, circular elliptical, etc. The container 100 may be formed from any material compatible with the blown extrusion moulding process, for example and without limitation, high density polyethylene, polyvinylchloride, polypropylene, etc.

Claims

1. A method of forming a container, the method comprising the steps of: forming an assembly comprising a pin received within a die, the pin comprising a slot extending partially along the pin; inserting molten plastics material into the aperture formed between the pin and the die, the molten plastics material being inserted under pressure such that a portion of the plastics material is impelled into the slot of the pin; causing the plastics material to conform to the shape of the die; transferring the plastic material from the die to a mould; and applying a source of pressurised gas to a portion of the plastic material to form a container, wherein the plastics material impelled into the slot of the pin forms a wall within the container to form two or more separate container regions.

2. A method according to Claim 1, wherein the die is configured such that the container is formed having two apertures.

3. A method according to Claim 1 or Claim 2, wherein the molten plastics material is inserted into the aperture formed between the pin and the die using an extruder.

4. A container comprising an internal wall, the internal wall forming two separate container regions within the container.

5. A container according to Claim 4, wherein the container comprises two apertures, each of the apertures being associated with the one of the separate container regions.

6. A container according to Claim 4 or Claim 5, wherein the container has a substantially round, elliptical, square or circular cross-section.

7. An arrangement for forming a container, the arrangement comprising: a pin located within a die; the pin comprising a slot extending through the pin and partially along the height of the pin; and the pin being received within the die such that the pin is separated from the die by an annular gap.

8. An arrangement according to claim 7 wherein the slot extends across the width of the pin.

9. An arrangement according to Claim 7 or Claim 8, wherein, in use, the arrangement is adapted to receive molten plastics material into the annular gap.

10. An arrangement according to any of Claims 7 to 9, wherein, in use, the arrangement is adapted to receive molten plastics material under pressure so as to impel a portion of the molten plastics material into the slot of the pin.

11. A method substantially as described hereinbefore and with reference to the accompanying drawings.

12. A container substantially as described hereinbefore and with reference to the accompanying drawings.

13. An arrangement substantially as described hereinbefore and with reference to the accompanying drawings.