EP0156627A2

EP0156627A2 - Vacuum bag fluid flow guide

Info

Publication number: EP0156627A2
Application number: EP85301956A
Authority: EP
Inventors: William T. Lloyd-Davies; William R. Scholle
Original assignee: Scholle Corp
Current assignee: Scholle IPN Corp
Priority date: 1984-03-22
Filing date: 1985-03-21
Publication date: 1985-10-02
Also published as: AU569942B2; AU4014485A; EP0156627A3

Abstract

An elongated strip of plastics in a flexible bag guides liquid in the bag to the bag outlet when a vacuum is applied to the outlet. The flow guide has structure which forms a plurality of interconnected spaces that in turn form flow paths in combination with the bag collapsing walls. The guide can take many forms including a net-like configuration, a pattern of alternate recesses and projections on each face of a strip, woven material, open cell sponge like material bouched randomly oriented fibres, material having spaced air bubbles between strips of plastic, or other such structures that can form flow paths in combination with bag wall Also disclosed is a stretched flexible tube havmg a spiral slot formed therein to serve as a flow guide Methods of making the bags and guides are further disclosed

Description

This invention relates to flexible bags used as containers for liquid, and more particularly to flexible bags having improved arrangements for withdrawing the bag contents.
Flexible bags confined within a box having come into widespread use in recent years for containing a large variety of liquids, particularly liquid food products. Such constructions offer a number of advantages and conveniences. As liquid is withdrawn from the bag, the bag collapses around the remaining contents, and air does not displace the liquid. This is desirable in that the absence of air helps maintain freshness and'delays spoilage of the bag contents.
With the dispensing outlet of the bag located in the bottom of the bag or in the lower portion of a side wall of the bag, the emptying action is very simple in that the remaining liquid in the bag is always around the dispensing outlet. However, in some operations, it is desirable to have the bag outlet near its upper end and the bag contents withdrawn by a suction pump. An example of this is when the bag contains syrup for soft drinks. In such a situation, the collapsing upper portions of the flexible bag are adjacent to the outlet with the result that, as the contents are withdrawn, the side walls of the bag can collapse against each other and seal the lower portion of the bag from the outlet, so that the bag cannot be emptied.
A suction tube can be attached to the dispenser pump and extend downwardly into the bag in an attempt to overcome this problem; however, the lower end of this suction tube can also be blocked by a wall of the bag being sucked into it. Further, pockets of liquid in the upper portion of the bag can be sealed from the lower end. As a further step for resolving this problem, a dip tube has been developed that has a plurality of slits extending axially in the side walls of the tube, with a rigid support ,.tructure within the tube to prevent the tube from collapsing. This construction which is shown in U.S.A. 4,286,636, prevents the walls of the bag from sealing off all inlets to the tube in that there is some portion of the tube open at all times to the liquid in the bag. A tube made by a coil spring having spaced coils, as shown in U.S.A. 4,138,036, is also useful in this regard. However, the relatively rigid tube approaches have some manufacturing and use disadvantages.
One of the features contributing to the low cost of flexible bags, as opposed to rigid containers, is that the bags can be made in a continuous interconnected strip of bags and then separated from the strip when the bag is to be placed into a box. Typically, the strip of bags is folded into a container for shipment to a customer, and the bags are then withdrawn from the container, and separated from the strip when they are to be used. Thus, when a relatively rigid suction tube is to be added, it is necessary that this operation be a separate manual step, which adds to the complexity and expense of use by the customer. Because of the high volume usage of such products, any cost saving in the manufacture or use of the bags can be quite significant.
Accordingly, a need exists for improving the system ensuring that the contents of the flexible bag container are properly emptied, while minimizing manufacturing costs of the structure utilized.
.According to the present invention there is provided a container comprising a bag for liquid, the bag having an outlet through which the liquid may be withdrawn from the container by means of a pressure differential between the interior and exterior of the bag, the flexible walls being unsupported internally so that they collapse against the remaining liquid when liquid is withdrawn from the bag, and means, extending from or near the bag outlet into the bag to a point remote from the outlet, for restricting the bag walls from collapsing to block the flow of liquid to the outlet characterized in that the said means comprises a flexible flow guide which has an elongated, generally strip-like configuration and which includes a structure which defines interconnected spaces throughout the guide forming paths leading towards the bag outlet, the size of the spaces and material of the guide being such that the guide prevents the collapsing bag wall from blocking said paths.
According to the present invention there is further provided a container comprising a bag for liquid, the bag having an outlet through which the liquid may be withdrawn from the container by means of a pressure differential between the interior and exterior of the bag, the flexible walls being unsupported internally so that they collapse against the remaining liquid when liquid is withdrawn from the bag, and means, extending from or near the bag outlet into the bag to a point remote from the outlet, for restricting the bag walls from collapsing to block the flow of liquid to the outlet, characterised in that the means comprises an elongated, plastics, fluid flow guide having a stretched tubular configuration with a spiral slot formed in its side wall, the size of the slot and material of the guide being such that the guide prevents the collapsing bag wall from blocking said slot.
According to the present invention there is further provided a method of making a plastics bag for containing liquid, with the bag having a flow guide positioned therein to help facilitate removal of the liquid when the bag walls commence to collapse against the flow guide as liquid is withdrawn from the bag, comprising forming the bags of thin, flexible plastic utilizing a strip-like plastics element as the flow guide, the flow guide having a structure forming a plurality of interconnected spaces that define flow paths leading to the outlet, characterized in that an end of the strip is heat sealed to the bag as an end seam of the bag is being formed by such heat sealing.
According to the present invention there is further provided a method of making flexible plastic bags with a flow guide in each bag for preventing the bag walls from blocking flow from the bag comprising:

extending an elongated layer of thin, flexible plastic material;
forming liquid outlet holes at spaced intervals in said layer;
inserting and attaching a nozzle to each of said holes;
extending a second layer of thin, flexible material coextensive with the first layer with said guide positioned between the layers;
securing the edges of said layers to each other to form side seams of a strip of bags; and
forming spaced bag end seams across said layers between the side seams with an end seam being located between a nozzle and said other end of the adjacent guide to thereby form a strip of interconnected, flexible bags with each having a flow guide therein,
characterised in that one end of an elongated flexible flow guide is attached to said nozzle with the other end of the guide extending away from the nozzle adjacent said layer before the two layers are brought together.

According to the present invention there is further provided a method of making flexible plastic bags with a flow guide in each bag for preventing the bag walls from blocking flow from the bag comprising:

extending an elongated layer of thin, flexible plastic material;
attaching elongated, flexible flow guides to said strip at spaced intervals so that there will eventually be one strip in each bag;
extending a second layer of thin, flexible material coextensive with the first layer with said guides positioned between the layers;
securing the edges of said layers to each other to form side seams of a strip of bags; and
forming spaced bag end seams across said layers between the side seams with an end seam being located between an attached end of one guide and said other end of the adjacent guide to thereby form a strip of interconnected, flexible bags with each having a flow guide therein;
characterised in that one end of the guide is attached at a location that a liquid port is to be formed in the strip with the other end of the guide extending away from the port.

In one embodiment of the invention, the guide has a net-like construction wherein a plurality of strands intersect in a manner to define tortuous paths to the container outlet. In one form of this embodiment, a first group of spaced strands cross a second group of spaced strands and are connected at the intersection. The strands of one group define a plurality of separated spaces which interconnect with a second group of separated spaces defined by the second group of spaced strands to define tortuous paths to the outlet. The spacing between the strands is coordinated and selected with respect to the flexibility of the bag walls so that the bag walls will not be drawn into the spaces so far as to prevent interconnection between one group of spaces and the other group of spaces. In another net-like construction, strands are woven in a manner to form interconnected spaces.
In another form of the invention, the guide strip has on each face a pattern of raised portions and interconnected recesses which define on each face continuous flow paths leading to the outlet. A similar structure has spaced/ plastic walled air bubbles between sheets of plastic forming the flow paths.
In yet another version of the invention, the flow guide is formed by randomly oriented, bunched fibres which are self adhering or interconnected by suitable material. A somewhat related structure is formed by plastic hook-like elements attached to a backing layer, or by loop-like elements attached to a layer. Such strips are similar to that used in the well-known fastener material, sold under the trademark Velcro.
The flow guide strips may be made as thick as needed to obtain the desired capacity and performances. In a preferred approach the thickness is obtained by stacking two strips with a slight space formed in the area between the strip edges. This is accomplished by joining one edge of one strip to the adjacent edge of a second strip stacked on the first, and then bending or rolling the stacked strips about the strip longitudinal axis, about 90°, before the other edges of the strips are joined. When released from the bent position, the flexible strips return to a generally flat position, but the strip that formed the outer layer when the strips were bent is slightly bowed between its edges, thus creating the desired gap.
A major advantage of the flow guides of the invention is that they are relatively flexible and relatively thin such that they can lie flat within a flattened bag. This eliminates the need for a separate step to insert a guide element after the bag is formed. Also, the flat strip-like guide can accommodate some folding of a strip of flexible bags, which is advantageous for handling and shipment. In a preferred approach, the guide is attached to the outlet in one wall of a flat bag before the wal: is joined to the other wall of the bag. The end of the giide remote from the outlet may also be attached to a bag well.
The invention is further described, by way of example, with reference to the accompanying drawings, in which:-

Fig1l is a cross-sectional view of a container of the invention with the flexible bag filled with liquid.
Fig. 2 is a view similar to that of Fig. 1, with a large portion of the liquid removed such that the bag walls have collapsed against the flow guide in the bag.
Fig.3 is an enlarged perspective view of the flow guide of Fig. 1 and a portion of the bag.
Fig. 4 is an enlarged perspective view of a section of the flow guide of Fig. 1.
Fig. 5 is a cross-sectional view on line 5-5 of Fig. 4.
Fig. 6 is a cross-sectional view on line 6-6 of Fig. 4.
Fig. 7 is a perspective view of an interconnected series of flow guide strips.
Fig. 8 is a perspective view of a series of flattened containers of the invention illustrating the manner in which the flow guides may be secured to the bags.
Fig. 9 is an enlarged cross-sectional view on line 9-9 of Fig. 8.
Fig. 10 is a plan view of a portion of another flow guide according to the present invention.
Fig. 11 is a cross-sectional view on line 11-11 of Fig. 10.
Fig. 12 is a perspective view of a woven flow guide construction according to the present invention.
Fig. 13 is a perspective view of yet another flow guide according to the present invention.
Fig. 14 is a schematic, fragmentary, perspective view of a flexible, multi-layered bag construction.
Fig. 15 is an end view of a flow guide made of two layers of the flow guide material illustrated in Figs. 3 and 4 with the layers joined so that a gap exists between their central portions.
Fig. 16 is a schematic, fragmentary, perspective view of a strip of open celled foam used as a flow guide.
Fig. 17 is a schematic, fragmentary, perspective view of flow guide material having air filled plastic bubbles between flexible plastic sheets.
Fig. 18 illustrates a schematic, framentary, perspective view of strips of a fastener material which may be used as a guide according to the present invention.
Fig. 19 shows a schematic, fragmentary, perspective view of woven material that may be used as a flow guide of the present invention.
Fig. 20 illustrates a schematic, framentary, perspective view of a bunched fibre material to be used as a flow guide according to the present invention.
Fig. 21 illustrates a cross section of a corrugated flow guide.
Fig. 22 is a schematic illustration of a method of making a strip of interconnected flexible bags each having a flow guide positioned therein during the manufacturing process.

Referring to Fig. 1, a container comprises a box 10 having a bag 12 confined therein, with the bag having thin, flexible, liquid impervious walls and being almost completely filled with liquid 13, such that the bag basically conforms to the shape of the box. The container includes a bag outlet 14 and an elongated flow guide 18 having one end connected to the outlet in some suitable manner and having its outer end extending downwardly into the bag to a point remote from the outlet, near the bottom of the bag. The flow guide 18 has a strip-like, generally flat configuration and is quite flexible. It normally extends in roughly a single plane, but it may undulate or twist somewhat if unsupported at its lower end. It is illustrated in Fig. 1 in a twisted configuration merely to illustrate that it has a relatively wide front and back face, but is quite thin.
When the contents of the bag are to be withdrawn, a vacuum pump, or other means for applying suction to the bag is applied through the outlet. If the box were to be oriented so that the outlet 14 is at the lower end of the bag, the liquid would flow out by gravity. As the liquid is withdrawn, the flexible walls of the bag are drawn inwardly and thus air does not displace the liquid. The bag might take the shape illustrated in Fig. 2 when there is not much liquid 13 left in the bag. As can be visualized from Fig. 2, the bag walls would actually be drawn against each other if the flow guide 18 were not provided and such action would seal the outlet from the liquid in the lower end of the bag. The presence of the flow guide enables liquid to be withdrawn from the outlet even though the bag walls are pressed against the sides of the flow guide. In accordance with the invention, the flow guide is constructed such that it forms a plurality·of interconnected spaces which define flow paths leading to the outlet so long as any significant portion of the flow guide strip is in contact with the liquid.
Referring to Fig. 3, it may be seen that the flow guide 18 has a net-like configuration formed by a large number of individual strands or elements creating a repeating, diamond-shaped pattern. More specifically, there is a plurality of spaced parallel strands 20 that extend at an angle with respect to the direction to the outlet 14, or at an angle with respect to vertical, as viewed in Figs. 1-3, and a plurality of spaced parallel strands 22 that is positioned behind the strands 20, as viewed in Fig. 3, or beneath the strands 20, as viewed in Figs. 4-6. The strands 22 extend at an angle with respect to vertical approximately the same as that of the strands 20, but intersecting the strands 20. In the fabrication of the net material, the groups of strands engage each other in a heated, softened state such that, when cooled, the strands are joined at the intersections 24.
Although the strands are joined at the intersections 24, they are not pressed together so as to be all in a single plane. The strands are somewhat merged at the intersections, but the centre lines of the upper strands form an approximate plane which is spaced from and parallel to a lower approximate plane formed by the centrelines of the lower strands 22. Stated differently, the upper strands 20 form an upper face of the guide strip and the lower strands form a lower face, recognizing that the guide can be in any orientation such that the terms "upper" and "lower" are merely used for reference purposes.
Thus, the upper strands 20, as viewed in Fig. 6, define a plurality of spaces 26, open to one face of the strip, while the lower strands 22, as viewed in Fig. 5, define a plurality of spaces 28 open to the other face. The spaces 26 and 28 are all open to the side edges of the strip. Also, the spaces are offset with respect to each other but are open to each other at each diamond-shaped space 27, defined by two segments of the upper strands 20 and two segments of the lower strands 22. That is, each space 27 is formed by portions of the spaces 26 and 28. Consequently, even when the bag walls 12 are compressed against the strip as illustrated in Figs. 5 and 6, fluid may flow through the netting spaces. That is, it can be seen from Fig. 5 that the spaces 28 are not closed off by the bag wall 12. Similarly, as seen in Fig. 6, the spaces 26 are not closed by the bag wall 12. Consequently, even with the bag walls pressed against the flow guide, the flow guide structure defines a plurality of tortuous paths as indicated by the arrows 30 in Figure 4. That is, liquid flowing in the spaces 28 defined by the strands 22 flows under the strands 20, but such liquid can flow into the spaces 26 over the strands 22 at any of the diamond-shaped spaces 27. Such tortous flow paths can lead to the bag outlet.
The actual dimensions and spacing of the flow guide strands are selected or coordinated with the flexibility of the material forming the bag walls. If the strands are too widely spaced, the bag material can be drawn into the space between the strands such that seals could be formed by the opposite bag walls engaging across the spaces 26 and 28, that is, through the spaces 27. Of course, the bag walls will extend inwardly to some extent into the spaces between strands, and thus the strand diameters cannot be made too small or else the bag walls could seal or the flow passages would be too small. In the arrangement illustrated, the spaces between the strands are about twice as large as the strand diameters. In a successful prototype product, a net having strands of about 0.045 inch (0.1143 cm) were used making a net strip thickness of about 0.085 inch (0.2159 cm).
The width of the guide itself should also be coordinated with the size of the strands and the spaces to provide the desired combined flow path. In a workable embodiment of the invention, the flow guide strip was about two inches (5.08 cm) in width. Wider or narrower strips may be employed, or a plurality of strips may be utilized. Also, multiple layers of strands can be used. Preferably, the length of the strip should be about equal to the height of the box 10 which surrounds the bag 12. This will ensure that the flow guide is always exposed to liquid, even when the liquid level is quite low.
The flow guide strip must be selected from material which is compatible with the liquid to be contained in the bag. Further, the material is preferably heat sealable and is relatively inexpensive inasmuch as the containers are disposable. It is also desirable that the material be relatively flexible and that it not be so rigid as to puncture the bag. On the other hand, it should not be so flexible that it will simply float in the liquid.
Referring to Fig. 7, one of the advantages of using heat sealable, flexible material is that the flow guide may be made as a continuous strip 32 of flow guides 18 with sections 36 between flow guides 18 being compressed so that they are not much thicker than the bag wall material. With this arrangement, the flow guide strips may be heat sealed to the flexible bag, with one end of the flow guide being heat sealed to one end seam of the bag and the other end of the flow guide being heat sealed to the seam formed at the opposite end of the bag. This can be done in a variety of ways. In a preferred arrangement, the bags are formed in a continuous strip as shown in Fig. 8 and a continuous strip of flow guides is inserted in the bags, properly located so that the flattened sections are aligned with the locations at which the bag inseams are to be formed. Thus, the bag end seams 38 and 40 may be heat sealed at the same time that the ends of the flow guides are heat sealed into the seam, as illustrated in Figs. 8 and 9.
Alternatively, the flow guide strip 32 of Fig. 7 can be severed at sections 36, and each guide individually heat sealed to a single bag 12 as the end seams 38 and 40 in the bag are formed.
In yet another approach, an individual flow guide 18 may be heat sealed to the bag walls at. some location near to, but spaced from the end seams of the bag, or one end attached to the outlet 14.
It should be noted that for any of the foregoing methods, one end of the strip should be attached to or positioned in close proximity to the bag outlet so as to make sure that the flow guide strip is in communication with the outlet. That is, the bag walls should not be able to seal between the flow guide and the bag outlet.
It should be recognized from the foregoing that elongated strip-like, generally flat, flow guides can be formed with a variety of structures and patterns. A common requirement is that the flow guide must have structure which forms a plurality of interconnected spaces that form, in combination with the bag walls one or more paths leading to the bag outlet. Thus, netting having any number of different patterns may be employed with the structure having a plurality of spaced strands somewhat like that described above. Further, the strands can be in a woven configuration, so lonq as they continue to define spaces that are interconnected and not blockable by the bag walls.
One example of this is shown in Fig. 12, wherein a plurality of strands 58 extending at one angle are woven with a plurality of strands 59 into a configuration forming spaces 57 between the strands. The strands are interconnected at their intersections so that the spaces are permanent. Since the strands extend alternately over and under each other, the spaces 57 are interconnected to form flow paths. It should be recognized from Fig. 12 that merely two strands could be woven into a repeating figure eight configuration with the strands alternating under and over each other. Further, interconnecting a group of such figure eight lengths in side by side relation would increase flow capacity. Of course, weaves or braids of three or more strands could also be used.
Figs. 10 and 11 illustrate another suitable embodiment of the present invention wherein a flat strip 50 made of suitable plastic is formed with a plurality of rows of raised portions or projections 52 alternately arranged with a plurality of recesses 54. In this embodiment each projection 52 is surrounded by a portion of the planar strip 50 and is further surrounded by four of the recesses 54 as well as two of the other projections 52. Thus, there is space 56 around each of the projections into which liquid may flow even when the bag wall 12 engages the projections as illustrated in Fig. 11. Further, the recesses 54, open to the space 56, provide additional flow path area through which liquid may flow.
One of the other major advantages of this construction, as observed from Fig. 11, is that the strip surface forming a projection 52 on one face of the strip forms a recess 54 on the other face of the strip. Similarly, each recess 54 on one face of the strip forms a projection 52 on the other face of the strip. This construction minimizes the material required while maximizing the flow space. Reducing the material required reduces cost and minimizes the amount of plastic that may absorb some of the liquid. A pattern of this nature can of course be made very inexpensively through a stamping or rolling operation. Further, if desired, holes may be formed through the strip to provide intercommunication between both faces of the strip. A variety of different patterns and a variety of different shapes for the projections and recesses may be employed. Further, a construction with only projections extending from a flat sheet may be employed.
In the arrangement of Fig. 13, a flow guide is formed by utilizing a plastics tube 60 which is formed with one or more slits in its wall, and the tube is then stretched beyond its memory to form one or more slots or gaps 62. Preferably the slot is in the range of 0.015 to 0.030 inch (0.0381 - 0.0762 cm) in width. In the form illustrated, the slot 62 has a continuous spiral configuration. As indicated above, the size of the spaces and the flow paths within the various flow guide constructions must be coordinated with the flexibility and thickness of the bag walls. Such bags are made of a variety of materials of different thicknesses and often the wall has more than one layer. A better understanding of this relationship may be realized by considering one type of bag wall construction currently used, illustrated in Fig. 14, having four layers of material, including an upper layer 66 which represents the inner wall of a bag, a middle layer 68 having an aluminized surface coating 70, and a bottom or outer layer 72. The layers 66, 68 and 72 are thin flexible sheets of plastics such a:i polyethylene or polyester. In one example, the inner layer 66 is made of polyethylene and is one mil thick, i.e. 0.001 inch (0.00254 cm) the middle layer 68 is made of polyester 0.0015 inch (0.00381 cm) in thickness, with the aluminium coating being very, very thin, and the outer layer 72 being a polyester film 0.001 inch (0.00254 cm) thick. Thus, the total bag wall thickness is only slightly more than 0.0035 inch (0.00889 cm). In other examples, the total wall thickness may be 0.004 or 0.0045 inch (0.01016 or 0.01143 cm). The layers are not usually bonded together throughout their entire surface but instead only on the edges or spaced intervals. Thus it is really the inner layer 66 which must receive the primary consideration with regard to cooperating with the flow guide. A film of polyethylene one mil (0.00254 cm) thick is very flexible and is also quite stretchable or extendable such that it can be drawn into small spaces by fluid pressure. Accordingly, in selecting the proper flow guide structure it is critical that the construction be such that the thin inner layer of the bag wall cannot be drawn so far into the flow guide structure, by the pressure differential applied to the bag during emptying, that the wall on one side of the flow guide can seal against the wall on the other side of the flow guide so as to block the flow.
Another flow guide structure that has been found to be particularly useful with very thin bag walls is that illustrated in Fig. 15. Shown is a two layer flow guide 74 having a lower layer 76 and an upper layer 78. Each layer is made of material like that shown in Figs. 3 and 4, but, of course, the layered approach can also be employed with the other flow guide structures described herein. The upper and lower layers are joined at their longitudinal edges 79 and 80 in a manner such that a slight gap 82 is formed between the layers. The gap is exaggerated in Fig. 15 for purposes of illustration. The advantage of the gap is that the pressure applied to the bag walls, in relation to the stiffness of the flow guide, is such that the layers 76 and 78 cannot be completely pressed together. This, coupled with the double thickness and with proper spacing between the strands of the flow guide, prevents even the most flexible inner bag w ls from being drawn so far inwardly that they seal the flow paths.
In another aspect of the invention, the flow guide 74 of Fig. 15 may be conveniently formed by first joining one longitudinal edge 79 of the upper and lower layers 76 and 78. The edges are preferably joined by heat sealing. The two layers, while stacked, are then bent or rolled into an arc of about 90° and held in that position while the other edges 80 of the upper and lower strips are joined. When the structure is then released, it will return to a generally flat configuration as illustrated in Fig. 15, but with the gap 82 being established.
Another suitable flow guide material that has been found to be successful is open celled foam 84, which is schematically illustrated in Fig. 16. The material is formed from a thermo-plastics and comes in a variety of densities and porosities. Typically, an open cell foam is made of thermo-plastics bubbles filled with gas which is allowed to expand and break during the manufacturing process. When the bubbles break, the bubble walls at the inter-engaging surfaces of the bubbles remain to form an open, net-like structure that has sufficient strength or stiffness, but the material remains flexible and resilient. The open nature of the cells forms a large number of flow paths through which liquid can flow even when resilient flexible bag walls are pressing against the surfaces of a flow guide made of such open cell material.
As indicated, the open celled foam comes in many varieties, typically being made of polyester or other suitable thermo plastics. In one satisfactory arrangement, the material has a porosity of approximately twenty holes per inch and a density of only three percent of solid. That is, the flow guide only displaced three percent of the liquid that would be displaced by a completely solid element. An example of such material is sold by Scott Paper Company of Chester, Pennsylvania, for a variety of uses, one being to be positioned beneath vegetables on display tables in supermarkets.
Fig. 17 illustrates another structure 86 that has been found to be practical as a flow guide. That structure includes a plurality of spaced, vertically extending, cylindrically shaped hollow elements 88 made of plastics and positioned between a lower film layer 90 and an upper layer 92. Spaces 94 are created between each of the hollow elements 88. A material of this nature is commonly utilized as cushioning material for packing breakable items. One example of such material is sold by Sealed Air Corporation under the trademark Bubble Pak. The "bubbles" or hollow elements 88, can be made in a variety of configurations, such as completely spherical or flattened spheres, as well as the cylinders illustrated. Also, the hollow elements may be made of different sizes and have differing spacing between them. One type of packaging. material has about three bubbles per inch. However, for use as a flow guide it is preferred that there be about fifteen bubbles per inch. This provides a plurality of small passages such that thin bag walls cannot be drawn very far into them. The liquid flow is, of course, through the spaces 94 formed between the hollow elements 88 and the upper and lower films 90 and 92.
Another readily available material, useful as a flow guide, is the well known fastener material sold under the trademark Velcro. Such material is illustrated in Fig. 18 comprising a lower layer 96 of thermo plastics material having a plurality of upwardly extending finger-like elements 98, and an upper layer of material 100 having a plurality of flexible loops 102 extending therefrom. Either material by itself is useful as a flow guide and the two layers may be used when fastened together in face to face relation. The fingers 98 actually have hooks on the end but fingers without hooks are also satisfactory.
Fig. 19 illustrates another suitable flow guide 104 having a knitted construction formed of continuous inter-engaging loops. Such structure is preferably made in a manner that the loops are permanently interconnected at their points of intersection, but the structure also functions as a flow guide if the loops are loosely connected, so long as the loops are sufficiently stiff to continue to create a plurality of interconnected spaces that can define fluid flow paths when the flexible walls of a bag engage the guide.
Fig. 20 illustrates yet another suitable flow guide structure 106 which is formed of a plurality of randomly oriented fibres that define a plurality of interconnected spaces to form flow paths even when under some compressive force trom the collapsing walls of a flexible bag. Again, the randomly oriented fibres are preferably permanently interconnected at their intersection points, and many materials are commercially available now that have such structure. They are typically made of thermo-plastics material, wherein the fibres are connected at their intersecting points during the manufacturing process. One example of such material is that used for air filters for furnaces. However, if the fibres have sufficient stiffness and friction they will not totally compress even if they are not actually interconected at their intersection points. The material will compress to some extent but will still maintain spacing between the fibres.
Fig. 21 illustrates the cross section of yet another elongated strip 107 forming a flow guide. As can be seen, the strip is a generally corrugated configuration wherein the strip forms with the bag walls a plurality of flow paths 109.
Referring to Fig 7, one of the advantages of using heat sealable, flexible material, is that the flow guide may be made as a continuous strip 32 of flow guides 18 with sections 36 between flow QUldes 18 being compressed so that they are not much thicker than the bag wall material. With this arrangement, the flow guide strips may be heat sealed to the flexible bag, with one end of the flow guide being heat sealed to one end seam of the bag and the other end of the flow guide being heat sealed to the seam formed at the opposite end of the bag. This can be done in a variety of ways. In a preferred arrangement, the bags are formed in a continuous strip, as shown in Fig. 8, and a continuous strip of flow guides is inserted in the bags properly located so that the flattened sections are aligned with the locations at which the bag inseams are to be formed. Thus, the bag end seams 38 and 40 may be heat sealed at the same time that the ends of the flow guides are heat sealed into the seam, as illustrated in Figs. 8 and 9.
Alternatively, the flow guide strip 32 of Fig. 7 can be severed at sections 36, and each guide individually heat sealed to a single bag 12 as the end seams 38 and 40 in the bag are formed.
In yet another approach, an individual flow guide 18 may be heat sealed to the bag walls at some location near to, but spaced from the end seams of the bag, or one end attached to the outlet 14.
It should be noted that for any of the foregoing methods, one end of the strip should be attached to or positioned in close proximity to the bag outlet so as to make sure that the flow guide strip is in communication with the outlet. That is, the bag walls should not be able to seal between the flow guide and the bag outlet.
Fig. 22 schematically illustrates another manner in which flow guides may be inserted into flexible bags formed in continuous strip form. An upper layer of film 110 is shown extending between a pair of rollers 112 together with a lower layer of material 111. These two layers form one wall 113 of a flexible bag. Spaced holes 114 are formed by a suitable punch 116 in wall 113, and a suitable spout or nozzle ll₈ is positioned in earn note and attached to the wall. The bottom bag wall 119 is also shown being formed of multi-layers 120 and 122, which are fed from supply rolls between suitable forming rollers 124. Before the bottom wall is mated with the upper wall 9, flow guide strip 126, which has been cut from a roll 128 of flow guide material, is secured by heat sealing or other suitable means to the flange of nozzle 118 which is in the interior of the bag. The flow guide lies flat and extends away from the nozzle, but its length is less than the distance between adjacent nozzles. The end remote from the nozzle, can be attached to the bag if desired. The upper and lower bag walls are then joined along their side edges by heat sealing of other suitable means, with the flow guide being thereby confined between the bag walls.
The flat tubular strip of bag material is then heat sealed transversely across the strip at spaced intervals to form end seams of a series of interconnected bags. The bag end seams are formed between the nozzle of one bag and the adjacent end of the flow guide which is attached to the nozzle of the adjacent bag. That is, the flow guide does not extend into the bag seams. As explained above, in one method of manufacture, the flow guide can intersect the seam. However, the thickness of the material of some flow guides make it desirable that the flow guide strip does not intersect the end seam, to not disrupt the sealing of the end seam. The strip of bags can be conveniently folded and shipped and stored in a box until use. The user thus does not need to take any assembly steps for inserting a flow guide into each bag.
Some strips of bags are formed wtihout having nozzles or holes for nozzles formed in the bags. Instead, all edges of the bags are sealed and a liquid inlet or outlet port is formed by a probe or other such element inserted into the bag when the bag is to be filled. In that situation, the flow guide should be attached to the bag at or near the location that the outlet is to be formed.
In one embodiment the guide structure has a net-like configuration which is formed of material compatible with the liquid to be placed in the bag.
Preferably the net-like structure includes spaces which extend through the guide, opening to both faces of the strip and extending between side edges of the guide.
Preferably the net structure is formed by a first group of spaced strands, and a second group of spaced strands which intersect the strands of the first group and are interconnected at the intersections so that a plurality of spaces are formed between the strands.
More preferably when the strip is laid flat, the centre lines of the first group of strands define an approximate plane and the centre lines of the second group of strands define an approximate second plane spaced from and parallel to the first plane so that when the flexible bag walls are pressed against the guide, the spaces between the groups of strands remain interconnected.
Most preferably the strands of the first group and/or the second group of strands extend at an angle with respect to the direction of the paths leading to the outlet such that the spaces (26) between the strands of said first group and/or second group open to the liquid in the container at the guide edges as well as at the spaces of the strip between the edges.
In a further embodiment the guide is formed of a plastic and is heat sealed to the bag when a heat sealed seam (38, 40) is formed in the end of the bag.
In another embodiment of the invention the guide has projections on one face and said projections are hollow.
Preferably the guide comprises a second layer of material spaced from the first layer and attached to said projections so that the flow paths are between said layers and around the projections.
In another embodiment of the invention the guide comprises two layers joined along their edges with a gap in between the layers.
Preferably one of said layers is curved relative to the other layer to form the gap.
In another embodiment of the invention the guide is formed of woven material.

Claims

1. A container comprising a bag (12) for liquid (13), the bag (12) having an outlet (14) through which the liquid (13) may be withdrawn from the container by means of a pressure differential between the interior and exterior of the bag (12), the flexible walls being unsupported internally so that they collapse against the remaining liquid when liquid is withdrawn from the bag (12), and means, extending from or near the bag outlet (14) into the bag (12) to a point remote from the outlet (14), for restricting the bag walls from collapsing to block the flow of liquid (13) to the outlet (14) characterised in that the said means comprises a flexible flow guide (18) which has an elongated, generally strip-like configuration and which includes a structure which defines interconnected spaces (26,28) throughout the guide (18) forming paths leading towards the bag outlet (14), the size of the spaces (28,26) and material of the guide (18) being such that the guide (18) prevents the collapsing bag wall from blocking said paths.

2. A container as claimed in claim 1, characterised in that said spaces (26,28) open directly to the liquid (13) in the bag (12) so that they can form inlets for said paths.

3. A container as claimed in claim 1 or 2, characterised in that said spaces (26,28) are not directly aligned, but instead are offset with respect to each other such that the paths formed are tortuous.

4. A container as claimed in any one of the preceding claims, characterised in that the guide (18) is formed of plastics and is heat sealed to the bag (12) when a heat sealed seam (38,40) is formed in the end of the bag (12).

5. A container as claimed in any of the preceding claims, characterised in that the guide (18) extends throughout the length of the bag (12) and the ends of the guide (18) are heat sealed to the ends of the bag (12).

6. A container as claimed in any of the preceding claims, characterised in that the guide (18) has one end secured to the outlet (14) or a location sufficiently close to the outlet (14) to prevent the bag walls from sealing together between said guide end and the outlet (14).

7. A container as claimed in any one of the preceding claims, characterised in that said guide (18) structure has a net-like configuration which is formed of material compatible with the liquid to be placed in the bag (12).

8. A container as claimed in claim 7, characterised in that said guide (18) includes a pair of strands (58,59) that are in a woven configuration that defines interconnecting spaces (57) between the strands.

9. A container as claimed in any of claims 1 to 6, characterised in that said guide structure (18) is formed by a planar strip (50) of plastics which has a series of portions or projections (52) formed in at least one of its planar faces surrounded by spaces (56) interconnected to form said flow paths.

10. A container as claimed in claim 9, characterised in that the guide (18) includes a pattern of recesses (54) around said projections (52) open to said spaces (56). -

11. A container as claimed in claim 10, characterised in that a recess (54) on one strip face forms a projection (52) on the opposite face.

12. A container as claimed in any one of claims 1 to 6, characterised in that said flow guide (18) is formed of an open celled foam material and said spaces (26,28) and flow paths are formed by the foam material.

13. A container as claimed in any one of claims 1 to 6, characterised in that said flow guide (18) is formed of woven material.

14. A container as claimed in any one of claims 1 to 6, characterised in that said flow guide (18) is made of randomly oriented bunched fibres.

15. A container as claimed in claim 14, characterised in that said fibres are interconnected at a plurality of intersections.

16. A container as claimed in any of claims 1 to 6, characterised in that said guide (18) includes a plurality of spaced loops attached to a backing sheet.

17. A container as claimed in claims 1 to 6, characterised in that the guide (74) comprises two or more layers (76,78) joined at their edges (79,80) with a slight gap (82) between the layers (76,78), said layers (76,78) being made of material which defines a multitude of interconnected spaces forming a plurality of fluid paths extending along the length of the strip.

18. A method of making the fluid flow guide as claimed in claim 17, comprising stacking two elongated, generally flat strips (76,78) made of flexible but somewhat stiff material, with one longitudinal edge of one strip (78) being joined to a longitudinal edge of the other strip (76), bending the two strips (78,76) into a curved configuration about a line substantially parallel to the longitudinal edges, joining the other two longitudinal edges while the strips (78,76) are bent, and releasing the strips from being bent, the strip material being such that the strips (78,76) will tend to return to the generally flat, unbent position, but the strip (78) that formed the outer layer of the bent configuration remains somewhat bowed, providing a gap (82) between the strips.

19. A container as claimed in any of claims 1 to 6, characterised in that said guide comprises a corrugated cross-section.

20. A container comprising a bag (12) for liquid (13), the bag (12) having an outlet (14) through which the liquid (13) may be withdrawn from the container by means of a pressure differential between the interior and exterior of the bag (12), the flexible walls being unsupported internally so that they collapse against the remaining liquid when liquid is withdrawn from the bag (12), and means, extending from or near the bag outlet (14) into the bag (12) to a point remote from the outlet (14), for restricting the bag walls from collapsing to block the flow of liquid to the outlet (14), characterised in that the means comprises an elongated, plastics, fluid flow guide (60) having a stretched tubular configuration with a spiral slot (62) formed in its side wall, the size of the slot (62) and material of the guide (60) being such that the guide (60) prevents the collapsing bag wall from blocking said slot.

21. A method of making a flow guide as claimed in claim 20, comprising cutting a spiral slit into a plastic tube (60) and stretching the tube (60) beyond its memory so that the slit forms a permanent spiral slot (62).

22. A method of making a plastics bag (12) for containing liquid (13), with the bag (12) having a flow guide (18) positioned therein to help facilitate removal of the liquid (13) when the bag walls commence to collapse against the flow guide as liquid (13) is withdrawn from the bag, comprising forming the bags of thin, flexible plastic utilizing a strip-like plastics element as the flow guide (18), the flow guide (18) having a structure forming a plurality of interconnected spaces (26,28) that define flow paths leading to the outlet, characterised in that an end of the strip is heat sealed to the bag (12) as an end seam (40) of the bag (12) is being formed by such heat sealing.

23. A method of making flexible plastic bags with a flow guide (18) in each bag (12) for preventing the bag walls from blocking flow from the bag (12) comprising:

extending an elongated layer of thin, flexible plastic material (113);

forming liquid outlet holes (114) at spaced intervals in said layer (113);

inserting and attaching a nozzle (116) to each of said holes (114);

extending a second layer (119) of thin, flexible material coextensive with the first layer (113) with said guide (126) positioned between the layers (113,119);

securing the edges of said layers (113,119) to each other to form side seams of a strip of bags; and

forming spaced bag end seams across said layers between the side seams with an end seam being located between a nozzle (116) and said other end of the adjacent guide (126) to thereby form a strip of interconnected, flexible bags with each having a flow guide (126) therein,

characterised in that one end of an elongated flexible flow guide (126) is attached to said nozzle (116) with the other end of the guide (126) extending away from the nozzle (116) adjacent said layer (113) before the two layers (119,113) are brought together.

24. A method of making flexible plastic bags with a flow guide (18) in each bag (12) for preventing the bag walls from blocking flow from the bag (12) comprising:

extending an elongated layer of thin, flexible plastic material (113);

attaching elongated, flexible flow guides (126) to said strip at spaced intervals so that there will eventually be one strip in each bag;

extending a second layer of thin, flexible material (119) coextensive with the first layer (113) with said guides (126) positioned between the layers;

forming spaced bag end seams across said layers between the side seams with an end seam being located between an attached end of one guide and said other end of the adjacent guide to thereby form a strip of interconnected, flexible bags with each having a flow guide (126) therein;

characterised in that one end of the guide is attached at a location that a liquid port is to be formed in the strip with the other end of the guide extending away from the port.