GB2314316A - Facilitating opening of plastics bags; closing bag mouths - Google Patents

Abstract

A plastic carrier bag has a pair of elongated tabs (13) which can be tied together to close the opening of the bag, and which also have a roughened surface (17) to help overcome the bag walls' tendency to cling together when initially opening the bag. Surface (17) is roughened by knurling, stippling or perforating so as to enhance friction when gripped by a user's fingers to open the bag.

Description

BAGS The present invention relates to plastic bags.

Plastic bags are nowadays used in a huge variety of applications, and on an enormous scale. One such application is in supermarkets and other food retail outlets where cheap, light bags are employed both to package individual items of food, such as fruit and vegetables, and at the check-out to package all of a customer's purchases. Advances in polymer technology have enabled plastic shopping bags to be formed from sheets as thin as 20 um or thinner while retaining the requisite strength. This decreases the cost of the bags as well as making them more environmentally-friendly.

One problem associated with such bags, however, is that their opposing walls tend to adhere together. This may arise due to static charges induced in the bags during their manufacture, in which case the phenomenon is known as "static cling". Our GB2271756 addresses this problem by proposing that carrier bags including sheet walls and a top opening are provided with a patch of roughness, for example on one of the walls. In use this patch enables a user to develop sufficient friction between his fingers and the bag to draw the walls apart.

The provision of such patches is thus worthwhile despite the overriding requirement that plastic bags are produced as simply as possible for mass production.

The present invention seeks to provide a plastic bag which is yet easier to use, while retaining its suitability for mass production.

In its most general terms the present invention proposes that the walls of the bag are provided with mutually connectable tabs, so that by connecting those tabs the top opening can be at least partly restricted, thus retaining within the bag any items which have been placed there. This feature hinders unwanted escape of items. It may be especially useful, for example, to a customer who wishes to transport shopping home in the boot of a car.

In a more specific aspect the present invention proposes a bag formed from plastics sheet material, and having a top opening and opposed side walls, each of the side walls including a tab which extends outwardly from the top edge of the wall, at least one at the tabs including an enhanced friction location. The tabs are suitable for connection together so as to permit the top opening of the bag to be at least partially restricted; for example the tabs may each be long enough to be tied together.

The friction enhancing location on the or each tab improves manual grip and thereby assists manual separation of the side walls. It has been found that by providing a friction enhancing location there, rather than (or in addition to) a friction enhancing location on the main area of the sidewalls, the ease of separating the walls is much enhanced.

Preferably, the tabs are provided opposing on the two sides of the bag. In this case the bags will usually be provided to the user with the tabs adhered together for example by static cling.

The user may conveniently separate the tabs by rubbing the pair of tabs in his hand, with his thumb touching one of the tabs and his fingers touching the other.

Preferably each of the tabs is formed as part of the same sheet as its respective wall, i.e. the tab is formed by shaping of the top edge of the wall. The thickness of the plastic sheets is typically less than 100 urn, and preferably less than 50cm. In the specific application of so-called "vest carriers" (shopping bags for use at check-outs of supermarkets) the thickness of each wall is typically between 15 and 25um. Such layers are typically formed of high-density polyolefin plastics, but any suitable plastics material may be used.

The friction-enhancing location may be made by forming physical roughness of the plastics material, for example by knurling, stippling, perforating or some other appropriate process. One suitable method of producing this roughening is described in detail in GB2271756, namely by impression of a rough element, such as a roller.

Preferably the bags are made by a continuous process utilising a single, continuous, original supply of bag material e.g. a roll of extruded plastics film which may be tubular. The method of producing such bags constitutes another aspect of the invention.

An embodiment of the invention is now described by way of example, with reference to the accompanying figures in which: Fig 1 is a front view of a vest carrier bag according to the invention; and Fig 2 is a perspective view of this bag in an open condition.

The bag shown in Fig. 1 is made from high-density polymer (e.g HDPE) film with a thickness of 20cm. It includes a rectangular front wall 1 with a corresponding back wall 3 (not shown in this figure). The two walls are connected by a straight seal 5 along the bottom and gusseted seals 7 down the sides to increase the useful volume of the bag. The walls extend up to loops 9,11 forming handles; top seals 12 close the tops of the loops.

A tab 13 extends from the top edge of the front wall 1, and a corresponding tab 15 (not visible on this figure) extends from the back wall 3. The tabs 13,15 are formed as part of the same sheet as the respective walls 1,3 of the bag. A portion 17 of the surface of each tab 13, 15 is roughened, as indicated by the hatching on Fig.

1. In the embodiment shown, the roughening extends over all of the tab except an outermost tip portion. It may extend onto the bag wall, e.g. as shown.

In the closed state illustrated in Fig 1 the front and rear walls 1,3 of the bag lie closely against one another and tend to be held together by static charges accumulated during manufacture. A user may, however, separate them by rubbing the pair of tabs 13,15 between the thumb and fingers of one hand. Each of the tabs is easily movable, compared to a portion of the corresponding wall, because it is not supported by plastics material to either side. The roughened surface provides good frictional engagement between the hand and the tab so that the tabs may be separated conveniently.

Subsequently, the two walls can easily be drawn apart by pulling the tabs apart.

Turning to figure 2, the bag of figure 1 is illustrated in an open condition ready to receive an item.

Once the bag has been filled, for example with shopping, the top opening between the walls can be restricted by connecting the tabs, for example by tying them together. For this reason the tabs are at least 5cm long, and in this embodiment are each about 10cm long.

In order to have sufficient strength to hold the walls together, while being easy to tie, each tab preferably has a width of from lcm to 4cm, and in this embodiment about 3cm. Each tab is formed as a substantially rectangular strip extending normally from the top edge of the wall, but the intersection between each edge of the tab and the top edge of the wall is rounded to reduce the stresses in that region.

Although only a single embodiment is shown, many variations are possible within the scope of the invention as will be clear to one skilled in the art. For example, it is possible, although not preferable, to form the two tabs displaced apart from each other along the top edge of their respective walls.

Claims (9)

1. A plastic bag having opposed side walls of plastics sheet material and a top opening, said walls having respective tabs which extend from their top edges and are connectable together to restrict the top opening, at least one of the tabs having an enhanced-friction surface.

2. A plastic bag according to claim 1 in which the tabs are elongate so that they can be tied together.

3. A plastic bag according to claim 1 or claim 2 in which both tabs have a said enhanced-friction surface.

4. A plastic bag according to any one of the preceding claims in which the plastics sheet material forming the walls and tabs is less than 50m thick.

5. A plastic bag according to any one of the preceding claims which is a vest carrier bag having handle loops.

6. A plastic bag according to any one of the preceding claims in which the enhanced-friction surface is provided by physical roughening of the plastics sheet material

7. A plastic bag according to claim 6 in which the enhanced-friction surface is knurled, stippled or perforated.

8. A method of making a plastic bag as defined in claim 6 or claim 7 comprising shaping and joining the plastics sheet material to form the bag having the tabs, and including subjecting the sheet material to the impress of a rough element to produce the enhanced-friction surface.

9. A plastic bag substantially as described herein with reference to the drawings.