GB2488782A

GB2488782A - Stronger Breaking Line

Info

Publication number: GB2488782A
Application number: GB1103819.7A
Authority: GB
Inventors: Boaz Kristal
Original assignee: L C S TECH Ltd
Current assignee: L C S TECH Ltd
Priority date: 2011-03-07
Filing date: 2011-03-07
Publication date: 2012-09-12
Also published as: GB201103819D0

Abstract

A stronger breaking line 36 for e.g. separating a single wipe 33 from a roll of wipes 34 or removing a portion of a filled bag (figs 3-4) for accessing the contents, comprises a wiggled line of a plurality of perforations. The line of weakness follows a wiggled or sinusoidal path, the pattern cyclically repeating. The amplitude 42 or cycle length (wavelength) 44 may be adjusted to adjust the strength of the breaking line. Where provided for opening a sealed bag the breaking line extends beyond the seams of the bag (64, figure 3) such that a corner or top portion of the bag can be completely removed. A zipper or the like may also be provided so that the bag can be re-sealed.

Description

WIGGLED CLEAVING PERFORATIONS

FIELD OF THE IN VENTION

The present invention relates in general to methods providing for "easy opening" sealed bags or packages and/or "easy cleaving" individual units that are serially connected to each other. In more particular the present invention relates to a method for enhancing the strength of breaking lines normally employed for easily separating individual units of items that are to mutually connected to each other, and/or breaking lines structured across a surface of sealed bags or packages to form a cover to an aperture to be easily opened by the user.

BACKGROUND OF THE INVENTION

A common method providing for easily separating individual units from a bunch of mutually connected units is normally implemented by means of breaking lines separating between any pair of mutually connected units.

Exemplary is a roll of wipes, or paper towels, such as described below with reference to Fig. 1. Roll of wipes 10 has a plurality of serially connected wipes such as wipes 14 and 16. Breaking lines such as line 18 separate between any pair of interconnected wipes disposed along stripe 20. Wipe 14, which is the outermost wipe of roll 10, is easily torn off by longitudinally pulling its free end (in a direction shown by arrow 22 that is substantially aligned along the axis of stripe 20). Breaking line 18, which is schematically shown, is laterally oriented relative to stripe 20.

Common breaking lines are normally implemented by a plurality of perforations or separated cuts structured along the breaking line considered.

Such perforations or cuts are referred hereinafter as perorations. The pores of a breaking line need not be intrusive, namely they need not cut through the sheet of the material from which such mutually connected units are made of.

For example, sealed bags having breaking lines that include a plurality of nonintrusive recesses structured across the surface of a wall of the sealed bag, which provide for cutting open an aperture through which the content of the bag is accessed, are common in the market place. Such niches although do not cut through the body of the sheets considered, are also referred hereinafter as pores or perforations. The introduction of breaking lines having intrusive and/or io nonintrusive perforations generate elongated regions across which the mechanical integrity of the wall of a bag, or the stripe of interconnected wipes or bags, is significantly weakened. By longitudinally pulling the end unit away from an exemplary roll of interconnected units, the component of the force exerted onto each separating piece, which is the piece of integral body that interleave between adjacent perforations reaches a specified level. Therefore when this level somewhat exceeds the respective level of strength the internal structure of the separating pieces (that interleave between adjacent perforations) enclosed within this region collapse. Such collapse starts at the weakest points of a respective separating piece in which the shearing strains are of significant or maximal levels; thereby these separating pieces are torn and the respective end unit is cleaved off the bunch of interconnected units.

Setting the level of strength of common breaking line is accomplished by suitably selecting the geometrical shape of the pores involved; selecting whether these pores are intrusive or nonintrusive, namely are cut trough or just disposed across one face of the sheets considered; selecting the dimensions of the pores and/or their density, namely the width of the separating pieces as well as the number of perforations along a segment of a given length measured along the breaking line considered. Such selection is accomplished in consideration with the width and thickness of the sheets and the material from which they are made of. Namely the level of force by which an individual unit such as the exemplary wipe is to be pulled for tearing it off the exemplary roll of wipes has to somewhat exceed the level of strength of the breaking line adjacent to the wipe considered.

Known methods for setting a level of strength to linear breaking lines that provide for easy cleaving and/or easy opening include any of the following steps: (i) selecting the geometrical shapes of the perforations of the breaking line as well as selecting whether the perforations are intrusive or nonintrusive; (ii) selecting the dimension of the perforations; (iii) selecting the density of perforations namely, the widths of the separating pieces when the dimensions of the perforations are given.

Such selection is experimentally accomplished prior to the manufacturing of the bunch of interconnected units. Succh selection is accomplished in consideration with the material from which the body of sheets to be torn off and/or to be cut open is made of, as well as of their dimensions Is (the widths and thicknesses of these sheets).

A breaking line can be weakened by folding and/or by accidentally tearing its edge. Additionally, cases in which the breaking line considered is too weak happen quite often. For example a single unit is accidentally torn off the bunch of interconnected units even in cases in which an exemplary wipe which is longer compared to the length of the ready made pieces of wipe is desired.

Therefore there is a need for a method providing for enhancing the strength of such breaking lines, such that its level reaches a desired level strength or a level that is included within a predefined range of levels of strengths.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is an isometric view of a common roll of serially connected wipes; Fig. 2 is an isometric view of a roll of wipes having breaking lines according to a a preferred embodiment of the present invention; Fig. 3 is an elevational view of a plastic bag across a surface of which a lateral wiggled breaking line according to a preferred embodiment of the present invention is structured; Fig. 4 is an elevational view of a plastic bag in which a breaking line according to a preferred embodiment of the present invention is structured at a corner of the plastic bag.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

is In accordance with the present invention a method for enhancing the strength of a breaking line such as breaking lines separating an individual unit from a bunch of mutually connected units and/or breaking lines providing for cutting open apertures of sealed plastic bags or packages is provided.

Intrusive perforations or cuts, and/or non-intrusive recesses, pores or niches, cuts that are structured along a breaking line, all these aforementioned terms are referred hereinafter as perforations. Enhancing the strength of a breaking line according to the method of the present invention is accomplished by wiggling and/or curving the line into a predefined geometrical shape. The density of the perforations of a breaking line, according to the present invention is the number of perforation structured along a unit length that is measured along the breaking line considered.

Reference is now made to Fig. 2 in which a roll of interconnected wipes having wiggled breaking lines according to a preferred embodiment of the present invention is shown. Wipes 30 and 32 are disposed at the end of stripe 33 that hangs off roll 34. Wipes according to the present invention are made of paper and/or nonwoven fabric such as normally utilized in the industry.

Wiggled breaking lines of the invention, such as breaking line 36, separate between any pair of interconnected wipes. Outermost edge 38 that is generated by tearing off the outermost wipe of a roll is similarly wiggled such as wiggled breaking line 36. Continuously curving the breaking line is in accordance with the method of the present invention, as is further explained infra. Preferable geometrical shapes of wiggled breaking lines of the invention are cyclically or almost cyclically repeating. Breaking lines having curved corners namely those lines their orientation continuously changes in which the breaking lines do not have sharp corners are preferable. Sinusoidal or almost sinusoidal breaking is lines as shown in Fig. 2 are in accordance with a preferred embodiment of the invention. The direction of the resultant force exerted onto various points along the wiggled breaking line of the invention when the end unit is longitudinally pulled away (in the direction of arrow 40) significantly changes compared to the direction of the normal to the breaking line positioned at the respective point.

Therefore the magnitudes of the normal component of force exerted onto different separating pieces of material may significantly change compared to the level of force respectively exerted in the direction of arrow 40, for tearing off wipe 33. The majority of these separating pieces will experience levels of shear stresses that are lower compared to the level of force exerted onto wipe 33.

Therefore in a case in which the wiggled breaking lines such as breaking line 36 have perforations of the same geometrical shape, dimensions and density such as of a common linear breaking line, the level of force to be exerted onto a respective unit for cleaving it off by pulling it in the direction of arrow 40 will be higher. Namely, the level of force to be exerted onto wipe 33 for tearing it off roll Jo of wipes 34, is of larger magnitude compared to the level of force required for cleaving a respective wipe connected to the a respective roll having linear breaking lines of the same perforations and density.

The levels of two parameters can be varied according to the method of the present invention for further modifying the level of strength of a wiggled breaking line of the invention. These parameters are the level of amplitude 42 of the wiggles and their cycle length 44. Sinusoidal or almost sinusoidal s patterns are more favorable when manufacturing is considered. However, in cases in which the geometrical shape differs from sinusoidal or almost sinusoidal, one can average both above mentioned parameters for deriving effective amplitude and effective cycle length. The following explanation of the method of the present invention similarly applies in cases in which effective amplitude and cycle length are considered. Each of the terms amplitude and/or effective amplitude is referred hereinafter as amplitude. Each of the terms cycle length and/or effective cycle length is referred hereinafter as cycle length.

By increasing amplitude 42 while the density of the perforations of the breaking line considered is retained fixed one increases the length of the breaking line, the number of perforations as well as of the number of separating pieces that interleave between any two adjacent perforations. Therefore the strength of the wiggled breaking line is thereby enhanced. Furthermore, the direction of the normal to the wiggled breaking line associated with the majority of such added separating pieces deviates off the longitudinal or axial direction which is the direction of arrow 40. Namely, the magnitude of the respective normal components of the forces exerted onto such added separating pieces decreases as the respective directions of the respective resultant forces get closer to the respective tangents of the wiggled breaking line. Whereas decreasing amplitude 42 causes the opposite effect which is the decreasing of the level of strength of the wiggled breaking line considered. Alternatively, increasing cycle length 44 results in shortening the length of the breaking line considered a lower number of separating pieces included in the breaking lines considered. This means decreasing the level of the strength involved.

Decreasing cycle length 44 while retaining the density of perforations at a fixed level causes an increase in the level of strength considered due to a greater number of separating pieces that are included in this breaking line. However the number of separating pieces the direction of the normal to the breaking line associated with them is relatively close to the axial direction increases as well.

Therefore the resulting increase in the respective level of strength is moderate compared to the case in which the amplitude is increased. Whereas increasing the cycle length while the density of perforations is retained at a fixed level causes a decrease of the level of strength of the breaking line considered.

Enhancing the level of strength of breaking lines according to the method of the present invention is achieved by continuously curving and/or wiggling a breaking line considered. Further modifying the level of strength of wiggled breaking lines according to the method of the present invention is achieved by: (i) selecting e level for the amplitude or the effective amplitude of the wiggles, and/or (ii) selecting a level for the cycle length, or the effective cycle length of the wiggles.

Is Such selection is experimentally accomplished prior to the manufacturing of the sheets involved, in considerations with the material from which the body of sheets to be torn off and/or to be cut open is made of, as well as of their widths and thicknesses.

EXAMPLE

Breaking lines providing for easy opening of sealed and filled bags or packages are prone to be accidentally torn off due to the weight of the content that stresses the respective sidewalls. By suitably selecting the amplitude and/or the cycle length of the wiggled breaking lines of the invention prior to manufacturing the packaging considered, as described hereinabove, such fine tuning can be achieved. Thereby the risk of accidental opening of a sealed and filled bag is substantially decreased. Reference is now made to Figs 3 -4 in which sealed and fiiled plastic bags having a wiggled breaking line of the invention which is disposed in two different positions across a surface of the respective bag are respectively shown. Plastic bag 60 has a wiggled breaking line laterally disposed across the entire width of the respective sidewalls of bag 60. (One of these sidewall lies behind the plane of the drawing and therefore is not shown. The wiggled breaking line extends from one edge all the way up to the opposite edge such that the breaking line crosses both seams, which are schematically shown by dashed lines 64. Seam 66 need not be the only sealing means providing for sealing bag 60. Bag 60 can be also equipped with a zipper that provides for resealing the bag as known. Such zipper is placed between wiggled breaking line 62 and the opposite side of the bag. Obviously seam 66 may not be present as bag 60 can be manufactured of a folded foil of plastic and/or a tubular sleeve made of foil of plastic. Plastic bag 70 has a wiggled breaking line placed at its corner. Similarly to the description hereinabove the Is wiggled breaking line crosses both seams 74 and continues all the way up to any of both edges of bag 70. The bags or packaging need not be made of plastic resins bags having wiggled breaking lines however made of paper and or tyvek are in accordance with the present invention. (Tyvek(R) is a non-woven fabric made of polyethylene fibers.) For easy opening any of these bags one has first to grip the edge of the respective bag at one of its sides holding it by each hand at a respective side of the breaking line at a close proximity to the breaking line. Then further pull each side of the bag in one of two opposing directions. One of these directions points from the plane of the drawing towards the reader, whereas the other direction points into the drawing. Such puling starts tearing off both sidewalls starting at the very edge and continuing all the way up to the other edge.

Cuffing open any filled and sealed bag or package having a breaking line that structures a cover to an aperture to be cut open by the user is fully equivalent to cleaving the cover of the aperture to be further removed off the bag or package. Therefore both operations easy cleaving" and "easy opening" are simultaneously referred hereinafter as cleaving. The items either bag or package, each of them is referred hereinafter by bag. The cover such structured is equivalent in this sense to a unit interconnected to the bag or package considered. Therefore such cleaving a unit that is interconnected to another unit similarly applies hereinafter to units that are mutually interconnected such as the exemplary wipes described hereinabove.

Furthermore a bunch of interconnected units may include at least two units.

Therefore cleaving a cover off a sealed bag or package for cutting them open, as well as cleaving a wipe off a bunch of interconnected wipes, or cleaving a io unit off a bunch of interconnected units, all these operations are referred hereinafter as cleaving a unit off a bunch of interconnected units.

Claims

CLAIMS1. A method for enhancing a level of strength of a breaking line separating between two interconnected units of a bunch of mutually interconnected said units, wherein said breaking line has a plurality of perforations of a given geometrical shape, dimensions and density, said method comprising continuously wiggling said breaking line such that said breaking line which is a wiggled breaking line comprises cyclically repeating wiggles, wherein said units selected from a group of units consisting of a wipe, a cover to an aperture structured across a* surface of a sealed bag, wherein said aperture intended to be cut open by a user of the content of said bag, a sidewall of a bag and any combination thereof, and wherein said bunch comprises at least two of said units.
2. A method as in claim 1, further comprising modifying said level of strength of said wiggled breaking line by selecting a valUe for the level of the amplitude of said wiggles.
3. A method as in claim 1, further comprising modifying said level of strength of said wiggled breaking line by selecting a value for the level of the cycle length of said wiggles.