Food or edible material: processes – compositions – and products – Packaged or wrapped product – Having consumer oriented diverse utility
Reexamination Certificate
1998-12-31
2003-08-26
Bhat, Nina (Department: 1761)
Food or edible material: processes, compositions, and products
Packaged or wrapped product
Having consumer oriented diverse utility
C426S123000, C426S127000, C383S207000, C383S208000
Reexamination Certificate
active
06610338
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to bags, packages or packaging material which can easily be torn, without the need for scissors, for instance. In particular, although not exclusively, the invention relates to sealable plastic bags for the containment of food or beverages. However the invention is not limited in its application to food packages and may have application to other industries such as pharmaceuticals
2. Background to the Invention
The waterproof, air-tight and durable nature of plastic bags means that they are widely used for packaging goods. Various ways for facilitating the opening of such bags are known. The simplest approach is to print a line on the bag to indicate where an opening should be cut. This cut might open directly onto the contents of the package (eg
FIG. 1
) or it might open onto a spout integrated into the package (eg
FIG. 2
; see also U.S. Pat. Nos. 4,491,245, 4,793,121 & 4,935,283 and the “Ampac™ spout-pack”). Such a spout also makes a convenient opening for the insertion of a drinking straw.
Bags are also available which can be opened without the need for scissors. Whilst this can be achieved very easily by simply perforating the intended opening, this is not suitable where the package must be kept air-tight (eg liquids or perishable goods). To overcome this difficulty, it is known to integrate a guide wire or string into a package which, when pulled, opens the package (eg FIG.
3
). Another system incorporates two strong parallel tracks into the plastic which define a channel between them (eg FIG.
4
). The end of this channel typically contains a nick in the plastic. When tearing begins at his nick, the two tracks guide the tear down the channel, giving a straight tear.
U.S. Pat. No. 5,552,202 describes an arrangement for guiding a tear which utilises bonded strips of materials which differ in stiffness. This difference assists the breaking of the bond between the strips and guides a tear along the bond.
GB patent 1,147,846 describes how a thin strip incorporated in the body of a sheet can provide a guide for tearing. The thin strip may be either weaker or stronger than the body of the sheet. In the former case, the strip provides a weaker path through the film than the surrounding body, along which a tear is guided; where the strip is stronger, the strip can be easily torn out of the body of the sheet, thereby separating the sheet in two.
In GB patent 1,335,036, a tear is guided by incorporating a flexible reinforcement across a sheet of material. This reinforcement itself contains a localised line of weakness and a tear along the line of weakness is trotted to the attached sheet of material.
These tearing systems can also be integrated into re-sealable bags. Once the tear has been made, the bag can still be re-sealed by means of a ziplock for instance (eg FIG.
5
). This gives a tamper-proof re-sealable bag.
It is an object of the invention to provide further means for facilitating the tearing of a sheet of packaging material. It is a further object of at least a preferred embodiment of the invention to provide various types of packages which can be opened easily, and also to provide easy-tear materials and packages which can be manufactured at relatively low cost.
SUMMARY OF INVENTION
In accordance with a first aspect of the present invention, there is provided a bag formed of one or more sheets of flexible material wherein at least one of the sheets is multi layered including an inner layer and an outer layer relative to the interior of the bag, the inner layer having at least one line of weakness with the outer layer being substantially intact along the line of weakness and tearable along the line of weakness, wherein the line of weakness extends from a first edge of the bag.
It will be understood that the bag may comprise one or more sheets. Where the invention comprises two sheets, one or both of them may be multilayered with a line of weakness present in the respective inner layers. The following references to “sheet(s)” therefore may apply to either one sheet having the multilayered construction defined above or both sheets having this multilayered construction.
The line of weakness in the inner layer of the sheet(s) of flexible material acts as a natural guide during tearing of the material (“tearing line”), and can take various forms.
For example, the line of weakness may be a perforated line in the inner layer. In such a case, the individual perforations in the inner layer need not be circular in shape. It might, for instance, be a dot-dash perforation, or any interruption in the inner layer which substantially disconnects the two portions on either side of the line of weakness. As an alternative, the line of weakness may be a zone which is thinner and/or weaker than the rest of the inner layer. Furthermore, the line of weakness in the inner layer may be the interface between two pieces of material with their edges in substantial abutment. (eg see WO98/16382).
It will be apparent that, where a perforated or thin line is used to form the line of weakness, the inner layer will typically be formed from a single piece of material. Where essentially abutting pieces are used, however, the inner layer may be formed from pieces of different materials which together form the inner layer.
In preferred embodiments, the line of weakness is substantially straight.
In order to facilitate the initiation of a tear, preferred embodiments include a small opening, break, nick, notch or the like along the first edge of the bag. Suitably, the tearing line extends from the first edge of the bag to a second opposite edge. In this case, the nick may be disposed at or adjacent one end or both ends of the tearing line. Furthermore, the tearing line may be visibly indicated on the bag, for example by printing a dotted line at the relevant position.
Being situated in the inner layer, rather than the outer layer, the tearing line is less likely to break or split due to any internal pressure exerted by contents of the package. In addition, the tearing line is protected from external damage such as rubbing.
The inner layer of the flexible sheet(s) is preferably attached to the outer layer of the flexible sheet adjacent to the tearing line for substantially the length of the line of weakness.
The outer layer of the sheet(s) of flexible material can be formed from anything that can be torn. It can thus be formed from, for instance, plastic, paper, metallic film etc.
The inner and outer layers are preferably of the same size or area. The layers may extend across the whole area of the sheet(s) of flexible material.
The sheet(s) of flexible material may, however, comprise additional layers. For example, the outer layer of the sheet(s) of flexible material need not be the outermost layer of the package; nor need the inner layer be the innermost layer of the package.
Indeed, it may be desirable to ensure that the tearing line is not exposed to the contents of the package, for instance by adding a further layer to the sheet(s) of flexible material. Furthermore, if the sheet of flexible material is to be thermally bonded to another sheet of material ie laminated, it is preferred that it includes an additional layer which protects the tearing line from being sealed itself. This additional layer could, for instance, be heat-sealable at a temperature substantially below that required to melt the inner layer of material containing the line of weakness.
Sheet(s) of flexible material for use in the manufacture of bags or packages according to the invention can be produced in a number of ways. Where tie line of weakness in the inner layer is a perforated line, the sheet(s) can be formed simply by bonding two layers, one of which contains a perforated line. Alternatively, a thin band of material containing a perforation could be attached to a sheet(s) of flexible material to define the line of weakness.
Similarly, where the line of weakness is a thin zone in the inner layer, the material can be formed by bonding two layers of flexible
Bhat Nina
Ostrolenk Faber Gerb & Soffen, LLP
Teckson International Limited
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