BAG WITH SUPPORT BRACE
A bag formed of plastic film material has first and second side panels with a margin portion at a rear edge of the first side panel joining a margin portion at a rear edge of the second side panel at a rear seam. The rear seam along at least a part of its length is braced by a solid elongate brace of plastic material which is either fixed mechanically to the panels or is thermally welded to them.
This invention relates to a bag having a support brace.
DESCRIPTION OF RELATED ARTPlastic bags are a ubiquitous and highly practical mode of carrying things and there is a whole panoply of shapes and structures of such bags depending on the particular function of the bag. Many bags have handles of some kind or other. These may be merely formations in the material of the bag itself or may include additional elements which are attached to the main carcass of the bag and which provide added strength and convenience.
Of particular interest from the viewpoint of reducing packaging materials are plastic bags that might replace in the marketplace freestanding, relatively thick-walled plastic jugs. Such a replacement is desirable for many reasons. Firstly, the volume of plastic material required in thick-walled plastic jugs is generally much higher in comparison with plastic bags configured to function as jugs. Secondly, placing of graphic materials is much easier on plastic bags where simple printing directly onto a paper-like plastic sheet can be implemented. Conventionally, printing is done on to a ply of the plastic sheet material, a typical ply material being polyester which readily accepts industry standard printing inks. This is in comparison with stiff-walled jugs which generally have some contour in the walls making it difficult for a print head to seat against anything but a very small wall area. This may mandate a relatively expensive process step of attaching labels to the jugs. Finally, prior to filling, thick-walled jugs being stored or shipped take considerable space in comparison with a compact stack of flat plastic bags.
The structure of a handled bag that is to function as a jug should have the strength to hold granular or fluid contents. It should also have a form enabling it to be gripped in one hand, moved from a standing into a pouring position and back again, and, ideally, for the pouring position to be retained as substantially all the contents of the bag are poured from a spout or functionally similar devices. Throughout the use cycle, the bag should substantially retain a jug form and function until the contents have been emptied. Finally, such a structure must be easy to manufacture.
While bags with handles are known that can provide a substitute for jugs made of more rigid materials, further improvements are possible to improve the performance and manufacturability of such bags. Limitations and disadvantages of conventional and traditional approaches to bag-as-jug designs and manufacture thereof will become apparent to one of ordinary skill in the art through comparison of such bags with the present invention.
SUMMARY OF THE INVENTIONAccording to one aspect of the invention, there is provided a bag formed of plastic film material, the bag having a first side panel, a second side panel, a margin portion at a rear edge of the first side panel joining a margin portion at a rear edge of the second side panel at a rear seam, and a brace fixed to the rear seam along at least a part of its length, the brace being a solid plastic member. The plastic member can have a cross-sectional shape which is any of regular polygonal, circular, square, rectangular, elliptic, lamellar, star-shaped or irregular.
The rear seam can be part of a complex of seams and panels defining an interior storage space of the bag. Alternatively, the rear seam can be part of a handle, the bag further comprising a rear gusset extending between respective side seams, the respective side seams formed between the rear gusset and the first and second side panels, the first and second side seams being part of a complex of seams and panels defining an interior storage space of the bag, the handle being on the distal side of the rear gusset from the interior storage space.
The plastic member can be positioned in an elongate pocket formed between the first and second panels at the rear seam. Alternatively, the plastic member can be fixed between the first and second side panels at the rear seam. Alternatively, the plastic member can be fixed against one side of the rear seam. The rear seam can be sandwiched between the plastic member fixed to the rear seam on one side of the bag and a second plastic member fixed to the rear seam on the other side of the bag. The rear seam can include a first plastic member fixed between the side panels at the rear seam, a second plastic member fixed to the rear seam on one side of the bag, and a third plastic member fixed to the rear seam on the other side of the bag. In the two-plastic member and three-plastic member structures, the plastic members can be lamellar and can be joined by a spine portion to form a channel structure embracing a rear part of the rear seam.
The or each plastic member can be attached to the rear seam by rivets or other mechanical fixture device. Alternatively, the plastic member or members can be fixed to the rear seam by adhesive. In a further alternative, the plastic member or members can be fixed to the rear seam by being pinched between elements of a channel section plastic member.
The cross-sectional shape of the plastic member can vary along its length to present a thickened area ergonomically suited to gripping or to provide enhanced support at selected locations. The brace can have a first plastic member part fixed to part of the rear seam, a second plastic member part fixed to another part of the rear seam and an intermediate plastic member part spaced from and not fixed to the rear seam whereby to provide a handle part at the intermediate plastic member part. Such intermediate plastic member part can be bowed or angled outwardly to present a space between the handle part and the contents storage part of the bag.
The bag can further comprise an openable and closeable pouring fixture at the front of the bag.
According to another aspect of the invention, there is provided a bag formed of plastic film material, the bag having a first side panel, a second side panel, a margin portion at a rear edge of the first side panel joining a margin portion at a rear edge of the second side panel at a rear seam, the rear seam along a first part of its length braced by a solid elongate thickened region derived from a starter rod of thermoplastic material welded to the rear seam.
The rear seam can be part of a complex of seams and panels defining an interior storage space of the bag. Alternatively, the rear seam can be part of a handle, the bag further comprising a rear gusset extending between respective side seams between the rear gusset and the first and second side panels, the first and second side seams being part of a complex of seams and panels defining an interior storage space of the bag, the handle being on the distal side of the rear gusset from the interior storage space.
The thickened region can be derived from first and second starter rods thermally welded to opposite sides of the rear seam. The thickened region can alternatively be derived from a trio of starter rods, one welded between the side panels at the rear seam and the other two welded to opposite sides of the rear seam. The or each starter rod can have an initial cross-sectional shape which is any of round, square, rectangular, elliptic, star-shaped, regular polygonal, lamellar and irregular, whereby to obtain a desired cross-sectional profile of the thickened region following thermal welding. The starter rod can have varying cross-sectional shape and size along its length whereby to result in a thickened region at the rear seam which varies along its length.
For simplicity and clarity of illustration, elements illustrated in the following figures are not drawn to a common scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Advantages, features and characteristics of the present invention, as well as methods, operation and functions of related elements of structure, and the combinations of parts and economies of manufacture, will become apparent upon consideration of the following description and claims with reference to the accompanying drawings, all of which form a part of the specification, wherein like reference numerals designate corresponding parts in the various figures, and wherein:
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The material of the starter rod 46 must, in the embodiments of
A starter rod, as an alternative to being of solid, homogeneous plastic material, may have other plies or components which add desired characteristics to the rod material and the bag to which the resulting brace is applied. For example, as previously indicated, especially for a starter rod of rectangular or leaf form, the rod can have a polyester surface layer on the opposite face from a thermoplastic layer in order that the outwardly facing surface of the thickened region of the bag will take a conventional printing ink. Alternatively, or in addition, the starter rod can include a strength ply made, for example, of nylon.
As previously mentioned, the thickened region is advantageously effected at a bag rear seam to provide both a rudimentary handle function and a bracing function. A bag 10 somewhat different from the pouch bags previously illustrated is shown in
While it is normally convenient and advantageous to apply a strengthening brace at the rear seam 16, a strengthening brace can alternatively be applied at other seam positions where local or directional strengthening is desired. For example, as shown in the pouring bag illustrated in
To obtain a high production rate when manufacturing bags, processing operations are typically performed on a continuous web of plastic sheet material. During a production run, the web is fed continuously under tension from an input end where the web is unformed to an output end where, essentially, a complete bag has been produced and is cut from the web leading end. The web is led past a series of processing stations where processing operations are performed including, for example, positioning, stamping, cutting, folding and thermoplastic welding, depending on the stage of manufacture of the bag.
An important step in manufacturing the bag is making the seams. Essentially the parts of the perimeter of each bag panel is sealed to corresponding margin parts of the perimeter of other panels, including gusset panels, with one seam being left open to allow for filling by the customer. In the course of the production process, if the seams are to be thermally welded, then the bag parts to be welded must be made of a thermoplastics material or must have a thermoplastic ply which is brought against another thermoplastic material or ply in the course of the welding process. A hot press tool is used to apply heat and pressure to hot melt the polyethylene. The web may be subjected to several welding steps to form seams at or near the panel edges.
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The embodiments of the invention illustrated describe pouch bags which are generally rectangular in side plan. In such a pouch bag, for efficient use of plastic sheet material and ease of manufacturability, each of the several panels of the bag is generally rectangular, with seam welds along the boundaries of each panel where it joins other panels including some that may be gusset panels. However, any of the bag panels can have a shape that is other that rectangular, provided that adjacent panels have appropriate shapes as needed to make the boundary welds possible. For example, the front and back panels, which are the major panels in terms of determining the overall shape of the bag, may have a generally elliptic or triangular configuration. In addition, bag volume can be increased by adding a gusset elsewhere than at the bottom of the bag as shown by the illustrated embodiments or at the rear of the bag as shown in the
In each of the embodiments of the invention described, the bag is formed from sheet plastic material that is at least partly a heat-sealable thermoplastic material and sealing/welding is effected by heat sealing. Such materials include, by way of example and not limitation, polyolefins such as polyethylene and polypropylene, vinyl polymers, and the like. The materials may be low-, medium- or high-density polymers and may be single or multi-layer composite material. Composite laminated materials may include adhesive layers. Sealing resins such as ethylene vinyl acetate may be used to improve sealing of certain polymer layers and the use of such sealing resins may obviate the use of adhesive tie layers. The invention contemplates the use of thermoplastics films which are made of or which include, a barrier sheet material such as, for example, EVOH or a metal layer which provides a barrier generally preventing the transmission of gases. The thickness of the film material is selected mainly on the basis of the intended weight the bag must carry and generally ranges from about 2 to 20 mils.
The type of thermoplastic sheet material used will depend on the purposes to which the bag is to be put, whether it is easy to handle in manufacturing, whether it can be readily printed upon, whether it is waterproof, whether it is strong enough to resist tearing or bulging, etc.
A particular implementation uses a multi-ply plastic sheet material including a polyethylene layer which makes effective thermoplastic welds/bonds and has high strength, and a layer of polyester which accepts printed indicia very well. In the manipulation of the web portions, generally polyethylene surfaces are brought together where two parts of the sheet material have to be joined so that a bond/weld can be implemented by using thermoplastic heat sealing techniques rather than adhesive bonding. Similarly such manipulation is configured so as generally to present the polyester surfaces outwardly for application of print indicia. It will be understood however, that whereas thermoplastic welding of materials such as polyethylene is preferred, a bag according to this invention can be manufactured with any or all of the welded seams being substituted by adhesive seams.
In one example, the sheet plastic material of the bag has a polyethylene layer 1 to 7 mils thick, an adhesive polymer layer 0.1 to 0.5 mils thick, and a polyester layer 0.5 mils thick, the layers being coextruded or adhesively laminated. The layer thicknesses can be varied depending on desired sheet material characteristics. For example, the polyester layer which is better suited for accepting printed indicia than the polyethylene, can be made somewhat thicker to provided increased stiffness to the bag. This can be quite important where the bag is to function as a pouring bag and will be lodged or stored in an upright position similar to a jug. The multilayer plastic material can include additional layers of material depending on characteristics desired in the finished material. In another example, the plastic sheet material has outer layers of polyethylene so that both surfaces of the material are heat sealable. In yet another example, the plastic sheet material has a layer of nylon for added strength and/or a barrier layer such as metal foil, metallized polyester or EVOH. The selection of ply materials and the number of layers of each material is chosen for the particular properties desired in the bag. Thus, polyethylene has good heat sealing properties and relatively high strength. A copolymer polyethylene with high elastomeric content can be used where a softer material is required. The sheet film material or particular web portions used in the bag construction can be formed from thermoplastic film that has been oriented during manufacture to impart mechanical strength along a particular axis or at a critical stress site. Such oriented strength can be imparted by for example stretching at ambient temperatures, melt orienting during extrusion, etc. Heat sealing and bonding of layers of sheet material is effected by the application of temperature and pressure for a predetermined time at locations where the layers are to be heat sealed. The temperature, pressure and time are selected based on the particular nature of the sheet materials being bonded together. Bonding is typically effected at multiple bonding stations, with the bonded material subsequently being cooled.
Whereas the various welded seams, whether or not they incorporate a strengthening element, are shown as straight lines, other more complex weld shapes can be adopted for functional and aesthetic reasons. Thus, a weld may contribute to any or all of structural shape, strength sealing and “posture” benefits. For effective sealing, both to prevent loss of contents and also to prevent intrusion from outside of contaminants, weld elements must overlap at their junctions. If the weld seams incorporate a strengthening element, then it may be appropriate to use a strengthening element which is non-linear.
There have been described herein various embodiments of a bag structure. Also described in brief detail are particular production process steps involved in manufacturing such bag structures. Such embodiments and processes have features that distinguish the present invention from the prior art. It will be apparent to those skilled in the art that the bags and the manufacture thereof may be modified in numerous ways and may assume many embodiments other than the preferred forms specifically set out and described above. Accordingly, it is intended by the appended claims to cover all modifications of the invention which fall within the scope of the invention.
Claims
1. A bag formed of plastic film material, the bag having a first side panel, a second side panel, a margin portion at a rear edge of the first side panel joining a margin portion at a rear edge of the second side panel at a rear seam, a brace fixed to the rear seam along at least a part of its length.the brace being an elongate solid plastic member.
2. A bag as claimed in claim 1, the rear seam being part of a complex of seams defining an interior storage space of the bag.
3. A bag as claimed in claim 1, the rear seam part being at least part of a handle, the bag further comprising a rear gusset extending between respective side seams, the respective side seams formed between the rear gusset and the first and second side panels, the first and second side seams being part of a complex of seams defining an interior storage space of the bag, the handle being on the distal side of the rear gusset from the interior storage space.
4. A bag as claimed in claim 1, the brace attached to the rear seam by rivets.
5. A bag as claimed in claim 1, the plastic member positioned in an elongate pocket formed between the first and second panels at the rear seam.
6. A bag as claimed in claim 1, the plastic member fixed between the first and second side panels at the rear seam.
7. A bag as claimed in claim 1, the plastic member positioned against the rear seam on one side of the bag, and a second plastic member positioned against the rear seam on the other side of the bag.
8. A bag as claimed in claim 7, further comprising a third plastic member fixed between the first and second side panels at the rear seam.
9. A bag as claimed in claim 7, the rods being lamellar and joined by a spine portion to form a channel structure embracing a rear part of the rear seam.
10. A bag as claimed in claim 1, the plastic member having a cross-section which, along at least a part of its length, is one of round, rectangular, regular polygon, lamellar and star.
11. A bag as claimed in claim 1, the plastic member attached to the rear seam by adhesive.
12. A bag as claimed in claim 9, the channel structure attached to the sides of the rear seam by the rear seam being pinched between the lamellar rods.
13. A bag as claimed in claim 1, the cross-sectional shape of the plastic member varying along its length.
14. A bag as claimed in claim 1, the plastic member fixed to a part of the rear seam, another plastic member fixed to another part of the rear seam, the rods integral with an intermediate handle part extending between the two rods and spaced from a contents storage part of the bag.
15. A bag as claimed in claim 14, the brace bowed or angled outwardly s to present a space between the handle part and the contents storage part of the bag.
16. A bag as claimed in claim 1, further comprising an openable and closeable pouring fixture at the front of the bag.
Type: Application
Filed: Oct 29, 2013
Publication Date: May 1, 2014
Inventor: Michael Reid Martin (Toronto)
Application Number: 14/066,203
International Classification: B65D 33/02 (20060101);