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Flexible container

The present invention relates to a self-emptying, shaped, compressible, flexible container of relatively thick and rigid plastics material, where the container is intended for fluids, e.g. nutrient solutions, infusion solutions, blood etc, whereby the container includes a container body forming a fluid chamber. The container body is disposed with a first end portion with a suspension device protruding therefrom as well as with a second end portion with an emptying device protruding therefrom which is connected to said fluid chamber. The body is formed by two opposing walls that are joined at the end portions and along two longitudinal lateral edges.

In the case of containers intended for storage of fluids of the aforementioned kinds, there are stringent requirements that the containers should collapse completely during emptying so that no space above a fluid surface is formed in the container. Such a space creates the need for a supply of gas e.g. air so that the container will continue to empty or empty completely. Rigid containers of e.g. glass always require such a supply of gas, which is provided by means of e.g. tubular devices or quite simply, by allowing the gas to bubble upwards through the fluid. Supplying a gas however risks a change in the properties of the fluid, e.g. due to oxidation,' or the fluid being contaminated, unless special measures are taken to prevent this. By using containers which are so flexible that they are compressed (collapse) in step with emptying, it is however possible, as has already been stated, to avoid these aforementioned disedvan-tages.

Containers for the above-mentioned purposes are known, where the containers are manufactured from softened plastics material, e.g. PVC. Such containers possess however the disadvantage that the plasti-cisers diffuse into the fluid, thereby impairing its quality, espe-

O PI c ally with long-term storage in the containers.

Collaborating containers for the aforementioned purpose should thus be made of physiological y unobjectionable material, e.g. aluminium foil, polyolefins, PET or other unobjectionable plastics materials or of laminates of different materials, where at least an inner layer of the container wall consists of materials which does not have a negative effect on the fluid which is stored in the container.

Further requirements for the containers are that they have relatively thick walls in order to reduce the risk of them being punctured, the risk of gaseous exchange with the environment and/or the risk that incident light has a negative effect on the product.

A number of proposals for a self-emptying container with relatively thick walls, which is so constructed that it does not collapse of its own accord, have therefore been put forward. However, none of these solutions enables self-emptying of the entire fluid contents of the container, since a partial vacuum is gradually established in the container, whereby the flow of fluid constantly subsides and finally ceases, in so far as a gas and conventionally air is not admitted into the container.

In order to allow as complete emptying as possible, the application of a technique is also known where the fluid does not occupy the entire inner space of the container after it has been filled. A certain volume of gas (air) thus remains in the container, by which means the walls do not need to be drawn together to abutment against one another in order to allow complete emptying of the container. The disadvantage of this technique is the problems which occur during autoclave treatment of the full container, due to e.g. the considerable increase in the volume of the gas. It is thus highly desirable that the required gas quantity be reduced, and preferably eliminated. This requirement coincides with those of making the best possible use of the space available for filling in- the container^ and preventing the fluid from being affected by the enclosed gas.

The German patent application DE-OS 23 30 101 reveals a container consisting of e.g. a polyolefin and where the container is composed of two cup-shaped parts 11,12. The cup-shaped parts are articulately joined to one another along their long sides. At least one of the cup-shaped parts is divided into segments by means of grooves 4. The thickness and rigidity of the material are so selected that without the grooves the container could only be compressed with difficulty. The grooves are disposed in order to comprise fold-lines around which i.e. along which the segments of the cup-shaped parts are folded relative to each other. During folding together a certain deformation of the material in the segments occurs, but the internal tensions thereby created are released in that the segments are allowed to be folded (articulated) relative to each other in the above-mentioned fold-lines. In order to achieve the desired effect it is necessary that the grooves possess sufficient depth, and it is stated in the description that they should have a location inside the surfaces of the sections in the material arcs which are formed in sections at right-angles to the cup edge. At the same time as the grooves form fold-lines for the segments of the container body they comprise those reinforcements which stiffen the container body primarily in its longitudinal direction and make it more difficult for the segments, and thus the container body, to underqo bending movements in relation to the axial direction of the body.

In order to achieve the desired effect the longitudinal edges 3 are moreover designed to form tubular material arcs which comprise longitudinal reinforcements that stiffen the container in its longitudinal direction, at the same time as in the event of a partial vacuum in the container they contribute towards moving one of the cup-shaped parts to abutment against the opposite cup-shaped part, in that the segments of the former are displaced towards the corresponding segments of the latter, and with their shape primarily retained. It is thus evident that the patent specification describes a container where it is required as a condition for the complete compression of the container that a partial vacuum is created therein of an order of magnitude which in the case of a container, completely filled at the onset, is in practise impossible to attain when there is a small residual quantity of fluid in the container.

The purpose of the present invention is to achieve a self-emptying container of the kind described by way of introduction, where the container can not only be completely emptied, but also allows an emptying cycle where the flow quantity is primarily constant, since no resilient forces which have a negative effect on emptying are built up in the walls of the container.

The novelty of the invention consists primarily in that the body of the container displays end sections with primarily flat wall portions which pairwise form an angle with one another and which are joined to one another in end portions primarily shaped as tubular devices, where the primarily flat wall portions prior to be transition to each tubular device are located near one another, and preferably primarily abut one another. The tubular devices thereby form control and holding devices which ensure that as the container is emptied of fluid, the compression of the container is initiated in that the flat wall portions are moved towards one another in the highest located end sec-tion of the container body, i.e. the end section in which the suspension device of the container is found. In the end section which is located lowest during emptying, i.e. the end section in which the emptying device of the container is found, the tubular device ensures that the end section retains its shape, by the device counteracting the pressure forces produced by the fluid.

In accordance with the invention the container body is further disposed with primarily flat lateral portions which pairwise form an angle v/ith one another and are joined to one another along the lateral edges formed by the container between the aforementioned end portions. The pairwise primarily flat lateral portions preferably delimit centrally located wall segments. The container is thus primarily symmetrical around a plane through the tubular devices of the end portions.

The construction described means that during the emptying of the container the walls approach one another, whereby a reversal zone is fo ed in the upper half of the container in the wall which has the lesser rigidity. During continued emptying the reversal zone is dis- placed in a direction towards the emptying device. The reversal zone has an orientation which is in principle at right-angles to the longitudinal axis of the container and to the lateral edges og the container. Variations in the thickness and rigidity of the material in the container wall can however mean that in individual containers the reversal zone in its displacement advances in one of its edge regions, whereby the reversal zone orientation during displacement in the axial direction of the body of the container deviates from the aforementioned right-angle orientation of the axis of the container body.

In certain embodiments of the invention the container is disposed in order to change over the reversal zone to the opposite container wall, when the reversal zone passes central parts of the container body. This causes the empty container to assume an S-shape, which is to be preferred in certain applications with regard to the connection to, for example, a drip chamber that hangs below the container. The desired effect is achieved in that the wall in which the reversal zone is formed and displaced is somewhat less rigid than the opposite wall. This is achieved in certain embodiments by a controlled distribution of material in the manufacture of the container so that
opposite walls receive differing material thicknesses. In other embodiments one of the walls is provided with reinforcements in the form of e.g. one or more grooves or stiffening ribs.

In accordance with the invention it is thus possible to determine in advance the di splace εnt of the reversal zone during the emptying of the container. In those embodiments, where the entire extent of one wall is made more rigid than the opposite wall, the reversal zone is displaced during the entire emptying cycle in the less rigid wall, which thus at the conclusion of emptying bulges inwards and primarily

OMPI WIPO abuts the more rigid wall. A longitudinal section through the empty container has the shape of a crescent. In those embodiments where one wall is more rigid than the other container wall in the first end section of the container body and softer in the second end section of the container body, the previously mentioned S-shape of the empty container is obtained.

In a section through the container aimed primarily at right-angles to the axis of the container, the container wall displays opposing arc--shaped, arching surfaces of sections. A container wall shaped in this manner is self-stretching. However, it happens during the displacement of the reversal zone that the outward-facing arc-shaped material portions are changed to inward -facing arc-shaped material portions, i.e. facing the opposite wall . These reversed inward-facing arc-shaped material portions counteract the efforts of the adjacent outward-facing arc-shaped material portions of the wall to retain the shape of the container, and thereby reduce the pressure differential which is required between the interior and exterior of the container in order to achieve the compression of the container. In certain stages of the compression process even the inward-acting forces are so large that they exceed the outward-acting forces i.e. those forces which seek to maintain the shape of the container. By means of the balance between the inward- and outward-acting forces, an easily reversed container is obtained, whose walls in the final stage of compression are brought primarily to abutment against one another by means of the force which occurs in the reversal zone. This has the effect of completely emptying the container of its fluid contents without emptying requiring any partial vacuum in the container. In reality the container itself presses out the last part of its fluid contents.

The invention is described more closely hereinafter with reference to the drawings, where

fig. 1 shows a self-emptying container in accordance with a preferred embodiment of the invention, whereby the container is shown from the front in position of use,

fig. 2 a shows the container in accordance with fig. 1 viewed from the side,

fig. 2 b-c show a longitudinal section through the container in different stages of an emptying cycle,

figs. 3-5 show the sections III-V in the figures 2 a and 2 b
where the dashed lines have an equivalent to the sections designated by b in- fig. 2 b,

fig. 6 shows the section VI in fig. 1 and especially the end portions of the container body, shaped as tubular

With reference to figs. 1 and 2 a there is shown an embodiment of a shaped compressible fluid container of flexible relatively thick and rigid plastics material, e.g. a polyolefin. The container is shown in an initial position which is equivalent to that it occupies filled with fluid and disposed in order to be emptied. The container includes a body 1 which delimits a closed fluid chamber 2. The body has moreover a first end portion 3, henceforth sometimes termed upper end portion, with a suspension device 6 protruding therefrom, and a second end portion 5, henceforth sometimes termed lower end portion with an emptying device 4 protruding therefrom. In a preferred embodiment the container is shaped in one piece from a hose-shaped blank during sealing of the end portions and shaping of the suspension device and the emptying device respectively. The container is intended to form part of, and be emptied, in a closed system, i.e. in a system where no air is supplied to the interior of the container, in order to compensate for fluid removed from the container.

The end portions are shaped as tubular devices 3,5 which are joined to primarily flat wall portins 14 a,b and 16 a,b respectively of a first upper end section 12 and a second lower end section 13 respec- tively, of the container body 1. Aforementioned wall portions form pairwise an angle with one another and are prior to the transition to each tubular device, located near one another and preferably primarily abutting one another. As a rule the wall portions 14 a,b and 16 asb respectively are disposed in order to form with another an angle
o o in the range 40-120 , and preferably an angle in the range 60-100 .

The tubular devices thereby form mechanically stable control and holding devices which stabilize the shape of the container body in the region of the tubular devices.

The figures show the container body 1 composed of two opposite walls

7,8 which pass into one another during the formation of longitudinal distinct lateral edges in the form of fold-lines 9,10. A distinct lateral edge 9,10 refers therefore to one marked as such which is permanent even after the deformation of the container. In the embodi-ment shown the central parts of the lateral edges are primarily straight and terminate next to the tubular devices 3,5 with parts 9 a,b; 10 a, b angled towards the ax s of the container. At the lateral edges 9,10 the walls form an angle with one another which as a rule is located in the range 20-120 and preferably in the range 40-80 . In fig. 2a there is further marked a centre plane Cl which extends through the lateral edges 9,10 and the tubular devices 3,5 of the end portions. The centre plane divides the container into two primarily symmetrical halves.

The container body 1 consists of an intermediate section 11 which has two opposite primarily flat central wall portions 25,26 which pass into the upper end section 12 and the lower end section 13. The end sections pass in turn into the tubular devices 3 and 5 of said end portions. These, as do the v/al 1 portions 14 and 16, have a transverse extension with regard to a centre plane C2 which is at right-angles to the aforementioned centre plane Cl. The end portions are thus parallel to one another. The central wall portions are also joined to lateral walls 27 a,b and 28 a,b respectively which connect each central v/al 1 portion to longitudinal lateral edges 9,10 of the container body. The lateral walls 27,28 form in the filled container an

At, angle with one another and in a preferred embodiment connect the central wall portions to the longitudinal lateral edges along their entire length.

In other respects the v/al Is are so constructed that they are revers- able from an outer to an inner position in which they abut one another. In displacement to the position where the walls abut one another, only one of the walls changes shape in a first embodiment, in that it is moved past said centre plane Cl and folded around the lateral edges 9,10, which thereby function as hinges. In conjunction with folding around the lateral edges the latter are moved away from one another. In a second embodiment the upper part of one of the walls is moved during emptying past the centre plane to abutment against the upper part of the other wall, while the lower part of the other wall is moved in a correspondi g way past said centre plane Cl to abutment against the lower part of the first wall, whereby the emptied container seen from the side obtains an S-shape. The change in the shape of the container body in conjunction with emptying of the container is described in the following.

By designing opposite walls 7,8 of the container body so that one of them has greater mechanical stability than the other, it is possible to control the change in shape of the container body as it is emptied. When one entire container wall of the two is made more rigid than the other, a crescent shape is obtained during emptying. In those embodiments when an S-shaped final shape is sought, one (the upper) part of the container body is produced with one of the container walls more rigid than the other, while in the other (the lower) part this state of affairs is the reverse. The desired increase in rigidity is obtained e.g. by means of a suitable distribution of material in conjunction with the manufacture of the con-tainer, or by means of reinforcement profiles in the container wall, for example shaped as grooves or bands of thicker material. In certain embodiments the required control of the shape of the empty container is obtained in that at least one of the walls is disposed with an arc-shaped profile facing the opposite wall, in at least one of the pairs of the primarily flat wall portions 14 a,b and 16 a,b respectively.

Fig. 6 shov/s in detail how in certain embodiments each and every one of the tubular devices 3,5 of the end portions is disposed with a mechanically stabilizing and stiffening material accumulation 29 which extends in the longitudinal direction of the device.

The emptying of a container filled with fluid is described in
the following in conjunction with the figures 2-5. Section lines III,

IV and .V are included in figures 2 a,b and correspond to the figures 3-5. Fig. 2 a which shows a stretched container from the side
corresponds to the solid lines in figures 3-5 while fig. 2 b which shows a longitudinal section through a partially emptied container corresponds to the dashed lines in figures 3-5. In order to clarify the figures, fig. 2 b together with its equivalents in figures
3-5 are shov/n with markings for the fluid contents.

In order to empty a filled container it is suspended in the suspension device 6 and connected to a drip chamber, for example. During
the first part of the emptying cycle the primarily flat wall portions 14 a,b of the upper end section 12 approach one another in order to finally assume a position where their upper parts abut one

During the continued emptying cycle increasingly larger parts
of the wall portions are brought to abutment against one another whereby, when the region of abutment begins to approach the inter-mediate section 11, a reversal zone 24 is formed in one of the container walls 8. Tne reversal zone obtains an inward-facing and in principle arc-like shape which seeks to move the wall to abutment against the opposite wall. The pressure from the inclosed fluid and to a certain extent from the in principle outward-facing and arc-like part of the wall, located immediately below, prevents this movement however. As fluid leaves the container the reversal zone is moved in a direction towards the emptying device and thereby has an oπ'enta-

A* tion which is in principle at right-angles to the longitudinal axis of the container and to the lateral edges of the container. Variations in the thickness and rigidity of the material of the wall sometimes cause the reversal zone in the case of an individual container to advance in its displacement in one of its edge regions, whereby the orientation of the reversal zone deviates from that stated in principle above.

It has been shown in practice that during certain parts of the
movement of the reversal zone those forces which seek to compress the container are larger than those forces which counteract the change in shape. This is especially the case in the final stage of the emptying of the container, which ensures that the container is emptied of all its fluid contents. This phenomenon finds a
natural explanation in that the wall no longer has any underlying outward-facing and arc-like part that counteracts the inward-facing forces of the reversal zone.

In those embodiments where the container body is designed in
order to provide the empty container with an S-like shape, the
reversal zone moves from one of the walls to the other as it
passes the intermediate section 11.

In addition to the embodiments described the invention is applicable o a large number of embodiments within the scope of the claims.