EP0007181A1

EP0007181A1 - Plastic bag having reinforced handle portion

Info

Publication number: EP0007181A1
Application number: EP79301149A
Authority: EP
Inventors: Heikki Samuli Suominen
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-06-15
Filing date: 1979-06-15
Publication date: 1980-01-23
Also published as: FI58469C; NO791990L; FI58469B; DK252379A; FI781908A

Abstract

An improved plastic bag is disclosed in which integral handle portions extending upwardly adjacent the mouth of the bag are provided with reinforcement strips extending laterally across the handles, the lower boundary of the reinforcing strips having an undulating configuration which provides an extended length edge for the joint between the strip and the underlying bag material, thereby improving the overall strength of the bag and handle.

Description

Technical Field

The present invention relates to a type of plastic bag having reinforced handle portions.

Background Art

The invention is an improvement upon that disclosed in applicant's U. S. Patent No. 4,125,220. The bag disclosed in this patent includes integral handle portions which extend upwardly on either side of the mouth of the bag and are configured in a symmetrical waveform about the center line of the bag. Strips of reinforcing material extend across and are secured to the handle portions of the bags disclosed in this patent, the strips as disclosed having an essentially straight lower boundary edge which does not extend to the side seams of the bag.
. While the bags disclosed in applicant's patent have achieved a great measure of success in the marketplace, experience with them has shown that they sometimes will fail along the lower boundary edge of the reinforcing strips of the handle portions, particularly when the bag is required to carry loads approaching its design limitations. Thus, a need has been identified for a means to prevent or minimize this tendency of the bags to fail at this location.
A principle object of the invention is to provide an improved bag structure having reinforced handle portions which greatly reduce or eliminate any tendency of the bag to fail along the boundary edges of the handle reinforcing strips.
Another object of the invention is to provide such an improved bag structure which can be made following the simplified techniques disclosed in applicant's U. _S. patent.
These objects are provided only as examples; thus, those skilled in the art may perceive other desirable objectives and advantages inherently achieved by the disclosed bag structure. Nonetheless, the scope of the invention is to be limited only by the appended claims.

Disclosure of Invention

The above objects and other advantages are achieved by the various embodiments of the present invention in which a pair of opposing bag walls of plastic film materia, are provided, joined to each other to form a bottom edge, a pair of side edges and an open mouth. Integral handle portions extend from the bag walls on either side of the mouth and are provided with reinforcing strips extending across the handle portions, the lower boundary edges of the reinforcing strips having an undulating configuration. The undulating confiruation produces an extended length for the edge or joint between the strips and the underlying bag walls, which results in improved overall strength of the bag and a substantially reduced tendency to fail along the lower boundary edge.

Brief Description of Drawingg

Figure 1 shows a plastic bag of the type disclosed and claimed in applicant's U. S. Patent No. 4,125,220.
Figure 2 shows one embodiment of the present invention in which the reinforcing strips extend from one side edge to the other.
Figure 3 shows another embodiment of the invention in which the reinforcing strips have a single symmetrical undulation on their lower boundary edges, the strips extending only to locations between the bag edges.
Figures 4 and 5 show further embodiments of the invention in which the reinforcing strips have a plurality of undulations on their lower boundary edges.
Figure 6 shows yet another embodiment of the invention in which the reinforcing strips are located only on the handle portions and are narrower in width than the handle portion.
Figure 7 illustrates schematically how the bags of Figures 1 to 6 are manufactured. Best Mode for Carrying Out the Invention

The following is a description of the several embodiments of the invention, reference being made to the drawings in which like reference numerals identify like elements of structure in each of the several figures.
Figure 1 illustrates applicant's-patented bag structure which includes front and rear opposing bag wall portions 2, 4 formed from portions of a plastic film tubing, a bottom edge 6 formed from a portion of the edge of the flattened plastic film tubing from which the bag is made and side seams or edges 8, 10 formed by an appropriate sealing and cutting technique to attach wall portions 2, 4 to each other and to sever the bag from the flattened film tubing. The bottom of the bag may include an inwardly folded portion, not shown, to facilitate expansion of the bag in use.
Extending upwardly from and integral with wall portions.2, 4 are a pair of opposing handle portions 12, 14 which may be provided with a hole 16 to facilitate carrying and hanging the bag. The upper edge of each handle portion is shaped in a wave configuration which is essentially symmetrical about the vertical center line of wall portions 2, 4, as illustrated, with the lowest points of the wave configuration being located adjacent edges 8, 10 and the highest portion being located essentially on the center line. Thus, it is seen that the wavelength of the wave configuration corresponds essentially to the width of the bag at its open mouth.
Each handle portion 12, 14 is provided with a reinforcing strip or band 18 of suitable material which may be adhesively applied to the handle portions. Of course, other application techniques may be used and strips 18 may even be coextruded with the tubing from which the bag is made. The height "hs" of strip 18, as illustrated, is chosen to be somewhat less than the overall height "hw" of the wave configuration of handle portions 12, 14. Also, the strip 18 is located on handle portions 12, 14 between the highest and lowest points of the wave configuration so that no portion of the reinforcement material extends to side seams 8, 10. The strips thus have an essentially straight lower boundary edge 20 and an essentially straight upper boundary edge 22, as illustrated.
Figures 2 to 6 illustrate embodiments of the present improvement invention in which the lower boundary edges 24 of reinforcing strips 26 are provided with undulating configurations, as illustrated. As mentioned previously, bags having reinforcing strips with straight edge boundaries tend to fail under heavy loads. The undulating configurations shown in Figures 2 to 6, however, provide an extended length for the edge or joint between the underlying bag walls and the reinforcing strips. Thus, loads applied along the lower boundary edge apparently are supported by a greater length of material than would be the case with straight edges, which leads to improved load carrying ability. Whatever may be the precise mechanic bags with undulating edge boundaries 24 are stronger than those with straight edge boundaries 20, 22.
In the embodiment of Figure 2, reinforcing strips are provided which are greater in overall vertical height than the overall height of the wave configuration of handle portions 12, 14. This allows the reinforcing strips 26 to extend completely around the mouth of the bag from one side edge to the other. Edge 24 comprises a plurality of essentally sinusoidal undulations of smaller amplitude than the wave configuration of handle portions 12, 14; however, other non-sinusoidal undulations may be used in all embodiments of the invention, so long as the effect is to increase the overall length of lower boundary edge 24. Although smoothly changing undulations are preverred, even triangular undulations will provide some advantage.
In the embodiments of Figures 3, 4 and 5, lower boundary edges 24 having one, two and three undulations are illustrated; however any reasonable number may be used in the invention. In these embodiments the overall width of strips 16 and the wave lengths of the undulations are chosen so that each lower boundary edge 24 extends only to locations on bag walls 2, 4 and handle portions 12, 14 which are between edges 8, 10. That is, as in the case of the bag illustrated in Figure 1, no portion of the reinforcement material extends to side edges 8, 10.
In the embodiment of Figure 6, reinforcing strip 26 is provided with a lower boundary edge 24 and an upper boundary edge 28, each edge being configured in a large number of smaller undulations than those of Figures 3 to 5. Here, as in the bag illustrated in Figure 1, the reinforcing strips are located entirely within the handle portions 12, 14.
Figure 7 illustrates schematically the process by which bags according to the invention may be made. The complete details of such a process are disclosed in copending application serial number 920,613. A tube 30 of suitable plastic film material is flattened, as illustrated, to facilitate the sequential formation of a large number of bags. Reinforcing strips 26 are adhesively secured to either side of the flattened tubing at an essentially axial location. The wave configuration of handle portions 12, 14 is then cut through the tubing and reinforcing strips and holes 16 are at least,partially formed. The severed portions of the flattened tubing are then separated and seams 8, 10 are formed by appropriate heat sealing equipment. The bags are then separated along seams 8, 10. Those skilled in the art will appreciate that this process may be accomplished manually using hand controlled implements, or automatically as disclosed in serial number 920,613.

industrial Applicability -

The bags according to the invention are particularly suited for use as shopping bags and, due to their unique features and resultant durability, are adapted for repeated use by the initial purchaser. The bags may be made in a variety of sizes having a variety of thicknesses of the plastic film material, as necessary to accomodate contents of varying sizes and weights. The handle portions are sufficiently flexible to permit the bags to be hung thereby with contents already in the bag, for display or storage. In some cases, the bag may be hung by one handle only, to permit the contents to be removed for inspection or use without removing the bag from its hanger.

Claims

1. A plastic bag, comprising:

a pair of opposing bag walls of plastic film material joined to each other to form a bottom edge, a pair of side edges and an open mouth for the bag;

a pair of handle portions, one extending upwardly from each of said walls on either side of said mouth;

a pair of strips of material, one extending laterally at least across each of said handle portions, each of said strips being secured to its handle portion and including a lower boundary edge having an undulating configuration.

2. A plastic bag according to Claim 1, wherein each of said handle portions-comprises an integral portion of its associated bag wall and is shaped in a wave configuration symmetrical about a center line disposed substantially equidistant between said side edges of said bag with the lowest points of said wave configuration being located adjacent said side edges and the highest portion of said wave configuration being located substantially on said center line.

3. A plastic bag according to Claim 1, wherein each of said strips extends only to locations on said bag walls between said side edges.

4. A plastic bag according to Claim 1, wherein the width of each of said strips is less than the height of said handle portions, thereby defining an upper boundary edge for said strips, said upper boundary edge also having an undulating configuration.

5. A plastic bag according to Claim 1, wherein said undulating configuration is sinusoidal.

6. A plastic bag according to Claim 1, wherein each of said handle portions includes an opening extending therethrough, said opening being located at least partially within said strip of said handle portion.

7. A plastic bag according to Claim 1, wherein each of said pair of strips extends from one side edge to the other.

8. A plastic bag according to Claim 1, wherein said strips of material are adhesively secured to said handle portions.