ES2667023T3 - Method for manufacturing adjustable drawstring bags and adjustable drawstring bag - Google Patents

Abstract

Method for manufacturing adjustable drawstring bags comprising the steps of: providing a plastic material, extruding the plastic material to a longitudinal tubular sheet (2), cutting (104) longitudinally at least two strips (10, 11) of said sheet tubular (2), thus providing a U-shaped sheet (3) having two legs with an inner side (16), an outer side (17) and a free cut edge (18), carrying (106) the at least two strips (10, 11) on one of said sides (16, 17) of said legs adjacent to the free cut edge (18), folding (108) the sheet adjacent to the free cut edges over said strips to form hems (8) and sealing the hems to form tubular channels (19) in which the strips extend, thereby forming drawcords (9), sealing (110) transversely the U-shaped sheet to provide a plurality of bags, and subjecting a portion of said sheet tubular (2) to a reinforcement treatment to provide strip s reinforced (10, 11) and thus form reinforced adjustable cords (9), wherein said reinforcing treatment comprises one or more longitudinal sealing of said strips (10, 11) to form tubular adjustable cords (9) and provide a part of said tubular sheet (2) and / or the strips (10, 11) with one or more substantially longitudinal, transverse and / or inclined welds to provide the reinforcement of the adjustable cord (9).

Description

Method for manufacturing adjustable drawstring bags and adjustable drawstring bag

The present invention relates to a method for manufacturing adjustable drawstring bags, in particular, adjustable drawstring garbage bags, with reinforced adjustable laces. The present invention also relates to an adjustable drawstring bag of this type.

This method is known from US 3,196,757, in which hems are formed with adjustable cord access means in the margins that form the mouth of the bag, the hems being sealed with the body of the bag to form tubular channels that enclose continuous adjustable cords, usually in the form of tapes of a suitable material. In a particular embodiment according to US 3,196,757 the adjustable cords can be formed by cutting thin ribbons of the fabric material from the mouth of the bag. In this embodiment, a tubular sheet with a W-shaped fold is cut to form a folded fabric with a hem at each edge by cutting a lower portion of the W-shaped fold, and an adjustable cord is formed with a profile in the form of U from said lower portion.

These known methods are, however, disadvantageous in that the adjustable cord formed in such a way can be easily broken or deformed, such that it is effectively useless, during use.

An attempt has been made to overcome this problem in US 5,057,065, in which the extrusion of the sheet is carried out by means of two extruders that supply a first and a second molten resin to a special port in a die. Thus, a blown sheet is provided comprising two different resins and a longitudinal region, which is substantially thicker than the rest of the sheet, and which is subsequently used to form traction ropes. However, this method is inconvenient since it requires the use of additional material for the adjustable cords, which makes the resulting bags more expensive to produce. Another attempt of this type is known from EP 0348823 A2, on which the preamble of claim 9 is based, and on which, starting from a flat sheet, the hems for the adjustable cords can be formed by folding the edges of the flat sheet on strips cut from the sheet in an inward or outward direction, and in which the adjustable cords can be reinforced by doubling their thickness during folding.

Therefore, the object of the present invention is to provide a method for manufacturing adjustable drawstring bags which method provides an adjustable drawstring that is more robust against breakage and deformation using a minimum of material.

This object is according to the invention achieved by a method of the type mentioned above, whose method comprises the steps of providing a plastic material and extrusion of the plastic material for a longitudinal tubular sheet, longitudinally cutting at least two strips of said tubular sheet, thus providing a U-profiled sheet having two legs with an inner side, an outer side and a free cut edge, which carries at least two strips to one of said sides of said legs adjacent to the free cut edge, folding the adjacent sheet when cutting the free edges on said strips to form hems and seal the hems to form tubular channels in which the strips extend, thus forming adjustable cords, transversely sealing the U-shaped sheet to provide a plurality of bags and subjecting a portion of the sheet to a reinforcement treatment to provide reinforced strips and thus form esti cords Reinforced rationing in which the reinforcing treatment comprises any one or more of the longitudinal sealing of said strips to form tubular stretch cords and provide a part of the tubular sheet and / or the strips with one or more substantially longitudinal, transverse and / or welds. or inclined to provide reinforcement of the adjustable cords.

Such a method provides for adjustable drawstring bags that comprise stronger adjustable cords that are considerably less prone to breakage or deformation and therefore are considerably easier to handle. Furthermore, said method provides the achievement of such adjustable cords without the addition of any additional material to the sheet, thus keeping the amount of material used to a minimum. In other words, the method according to the invention is of conservation of mass since it provides reinforced adjustable cords while maintaining the mass of the adjustable cords substantially constant.

By subjecting a part of the sheet to a reinforcement treatment comprising one or more of sealing said strips to form tubular adjustable cords and providing a part of the tubular sheet and / or the strips with one or more substantially longitudinal, transverse and / or layers inclined welds to provide reinforcement of the adjustable cords, the adjustable cords thus formed are provided with additional strength, and therefore work best when a bag is closed.

According to another embodiment of the method according to the invention, the sealing of the strips is carried out by reducing the strips with a sealing knife, whereby the cutting and sealing of the strips can be performed simultaneously.

According to another embodiment of the method according to the invention, the welds are provided by carrying a heated wheel through a part of the tubular sheet and / or through all or a part of the strips, to provide said both welds in a particularly simple and direct way.

According to another preferred embodiment of the invention, the method further comprises the step of drilling at least one hole or at least one perforation in the sheet material, to provide for stretching of the adjustable cord when a bag is closed, which provides easy Access to the adjustable cord when you want to close a bag.

According to a preferred embodiment of the method the plastic material is a polyolefin, such as a polypropylene or a polyethylene, this material being particularly convenient and easy to handle in a process according to the invention.

According to a particularly preferred embodiment of the method according to the invention, a continuous line of adjustable drawstring bags is produced, each two bags being separated by a weakened line, thereby providing a method that results in a row of bags that can be rolled to form rolls of bags that contain a desired amount of bags and are ready for shipment.

According to another particularly preferred embodiment of the invention, the method is performed as an in-line method, thereby providing a particularly convenient saving method and time for the production of adjustable drawstring bags.

According to another preferred embodiment of the invention, the method further comprises the step of applying a coloring agent of a different color than that of the adjustable cord sheet. In this way, the adjustable cord becomes immediately visible to the user, and thus an adjustable cord bag is provided that is easier to use. For example, the coloring agent and the color of the sheet can be mutually contrasting colors.

Furthermore, according to the invention, an adjustable drawstring bag is provided comprising a U-shaped plastic sheet that provides a closed bottom, an open end and two sealed sides, a hem formed by folding and sealing the sheet at the end. open on it, and an adjustable cord placed at the hem, the adjustable cord being formed by at least two strips of the U-shaped plastic sheet material, in which the adjustable cord sheet has been subjected to a treatment of reinforcement, and the reinforcement treatment is one

or more of which the adjustable cord is a tubular cord formed by the longitudinal seal of said strips and that the adjustable cord comprises one or more substantially longitudinal, transverse and / or inclined welds that extend over all or a portion of the same cord .

This provides an adjustable drawstring bag that includes stronger adjustable strands that are considerably less prone to breakage or deformation and, therefore, are considerably easier to handle, the bag is produced using a minimum of material.

The result of the reinforcement treatment is one or more that the adjustable cord is a tubular adjustable cord and that the adjustable cord comprises one or more substantially longitudinal, transverse and / or inclined welds that extend over all or part of the adjustable cord . In this way, the adjustable cord is provided with additional resistance and, therefore, behaves better when closing the bag.

According to a preferred embodiment, the bag further comprises at least one hole or at least one hole in the sheet material, the hole or the hole being adapted to pull the adjustable cord when closing a bag, thereby providing a bag with Easy access to the adjustable cord when you want to close it, so the bag is more comfortable to use for the end user.

According to another preferred embodiment, the tubular plastic sheet is a polyolefin, such as a polypropylene or a polyethylene, this material providing bags that work particularly well.

According to another preferred embodiment, the adjustable cord comprises a coloring agent of a different color than that of the sheet, thereby providing an immediately visible adjustable cord.

The invention will now be described in more detail based on a non-limiting embodiment, and with reference to the schematic drawings. In the drawings,

Figure 1 shows a section of longitudinal tubular sheet with four step indication of the method. Figures 2A-2E, where Figures 2B-2E do not illustrate the present invention, show a cross-sectional view of the sheet in Figure 1 as indicated by lines IIa-IIa to IIe-IIe, respectively, showing the Result of different stages of the method, Figures 3A and 3B are views similar to Figure 2E, but showing two other embodiments of the adjustable drawstring of a bag, where Figure 3A is an embodiment according to the invention and Figure 3B does not it is, and

Figures 4-6 show schematic side views of three different bags according to the invention.

With reference to Figure 1, an embodiment of a method for manufacturing adjustable drawstring bags, and particularly garbage bags of adjustable drawstring, according to the invention is shown. The illustration shows the main stages of the method according to the invention.

In the manufacture of an adjustable drawstring bag using the method of the invention the following steps are carried out. First, a plastic material is provided, generally in the form of granules. This stage is not shown in the figures. In principle, any suitable plastic material that is suitable for processing on a thin, flexible and strong sheet can be used. Preferably, the plastic material may be heat welded. Preferably, the plastic material is a polyolefin, such as a polypropylene or a polyethylene, where suitable polyethylenes comprise high density polyethylene (HD), low density polyethylene (LD) and linear low density polyethylene (LLD). Alternatively, the material can be a biologically degradable plastic or a bioplastic. Next, the plastic material is extruded into a thin sheet of tubular plastic 2 through the use of a suitable extrusion process. Such extrusion processes are as such well known in the art. An illustrative cross section of an extruded tubular sheet is shown in Figure 2A showing the flattened tubular sheet as would be the case during the manufacturing process. In step 104, see Figure 2B, at least two strips 10, 11 are cut longitudinally, that is, parallel to the direction of advance indicated by arrow 15 in Figure 1 of the sheet, from the tubular sheet 2, whereby a U-profiled sheet 3 is provided having two legs each comprising an inner side 16, an outer side 17 and a free cutting edge 18 - see Figure 2C.

The cutting process of step 104 is preferably performed using a sealing knife, such as a so-called slit sealer, which is a knife that can be heated on one or both sides to perform simultaneous cutting and sealing of a plastic sheet. Referring to Figure 2B, two sealing blades are used in a method that is not in accordance with the invention. The sealing blades are represented by lines indicating a first sealing blade 21 and a second sealing blade respectively. In the method steps indicated in FIGS. 2A-2E, the first sealing blade 20 is insulated on the side facing the strip 11 and heated on the side facing the strip 10, while the second sealing blade 21 is insulated on both sides (hence the second sealing blade 21 can in this principle method be replaced by a suitable ordinary blade), thus providing the adjustable cord 9 shown in Figure 2C and 2D having a U-shaped cross section Alternatively, in one embodiment according to the invention, the first sealing blade 20 is heated on both sides, while the second sealing blade 21 is heated on the side facing the strip 10 and is isolated on the side opposite the strip 10. This configuration provides an adjustable cord 9 with a tubular cross section as shown in Figure 3A. Said adjustable cord has the advantage of greater resistance compared to the adjustable cord described above with a U-shaped cross section. It should be noted that, in principle, any combination of heated and insulated sides of the two sealing blades 20, 21 it is feasible provided that a condition is met, namely that the side of the second sealing blade 21 in front of the rope 10 must always be insulated to ensure that the opening formed between the free cutting edges 18 of the bag is not sealed.

In an alternative embodiment of the adjustable cord 9, it can comprise one or more substantially longitudinal, reinforcing welds (not shown) that are preferably placed at a distance to form the edge of the adjustable cord. Such reinforcement welding can be, for example, punctual, linear with interruptions or continuous, and is preferably provided by means of a heated wheel that is driven through the strips 10, 11 or a longitudinal section of the tubular sheet 2 which is it subsequently cuts the strips 10, 11 into shape 104, such a wheel, which can be heated, can also be used as an alternative to the sealing blades mentioned above, particularly when the wheel is further adapted to be able to cut. Alternatively, the reinforcement welds can be transverse or extend inclined or diagonally through the strips 10, 11 or a longitudinal section of the tubular sheet 2 that is subsequently cut in step 104 to form the strips 10, 11. The welds of reinforcement can join together the legs of the U-shaped adjustable cord, thus providing the adjustable cord with areas that are substantially twice the thickness of the tubular sheet material.

Next, in step 106 the two strips 10, 11 are conducted on one of the sides, for example each outer side 17 or any of the inner sides, of the legs of the profiled sheet of U 3 adjacent to the cutting edges free 18 (see figure 2C).

Another adjustable cord configuration, which, however, is not an embodiment of the present invention, is shown in Figure 3B with a twisted adjustable cord 9. The twist of the adjustable cord 9 can, advantageously, if the adjustable cord 9 is tubular or U-shaped in cross section, be made by twisting the two strips 10, 11 during step 106 as part of the guiding stage of the strips 10, 11 on one of the sides, for example, either the outer side 17 or either the inner side of the legs of the U-shaped sheet 3. Such twisting is another way of increasing the strength of the adjustable cord 9.

After step 106 of the adjacent sheet the free cutting edge 18 is, in step 108, see also Figure 2D, folded over the strips 10, 11 to form hems 8. The hems 8 are subsequently in step 110, see also Figure 2E, sealed to form tubular channels 19 in which the strips 10, 11 extend, forming the strands of the adjustable cords 9.

During or, preferably, before step 104 of the tubular sheet 2 is as shown in Figure 1 provided with holes 12 for, during use of the final bag, to stretch the adjustable cord when it is desired to close the bag. Said holes 12 are generally drilled in the sheet along its longitudinal axis, that is, the direction indicated by arrow 15 of Figure 1, of the sheet at regular intervals, thus providing at least one hole for each drawstring bag. adjustable end. As an alternative to such holes 12, the sheet 2 may be provided with perforations (not shown) that serve the same general purpose facilitating access to the adjustable cord. Such perforations may, in principle, be provided to the plastic sheet at any point in the manufacturing process, but preferably they are provided before or during step 104 or alternatively at some time during or after step 110.

Finally, in a stage not illustrated, the profiled sheet of U 3 is sealed transversely, that is, substantially perpendicular to the feed direction indicated by arrow 15 in Figure 1, at suitable intervals to provide a plurality of bags of a width wanted. Therefore, the depth of the bags is consequently determined by the diameter of the initially extruded tubular plastic sheet 2. In addition, the transverse seal can be provided with a weakened line, such as, for example, a row of perforations, which separates each of the two bags, so that a continuous line of adjustable drawstring bags can be produced.

The method according to the invention can be carried out as an off-line method, that is, the realization of the initial extrusion and subsequent profiling of the extruded sheet (steps 104-110, plus the final stages mentioned above) separately, for example, by rolling the extruded sheet into a roll and providing a profiling machine with the sheet roll thus produced. However, in the most preferred embodiment, the method is carried out as an in-line method, thus carrying out the complete manufacture from extrusion to final bags in a production line.

Turning to Figures 4, 5 and 6, three different configurations of adjustable drawstring bags 1, preferably adjustable drawstring garbage bags, according to the invention are shown. Each of the bags 1 comprises a U-shaped plastic sheet 3 with a closed bottom 4, an open end 5 and two sealed sides 6, 7. Each bag 1 further comprises a hem 8 that is being formed by bending and sealing the sheet 3 on itself at the open end 5. An adjustable cord 9 is placed on the hem 8 of each bag 1. The hem 8 is placed externally on the U-shaped plastic sheet 3, and the adjustable cord 9 is formed by at least two strips of the material of said U-shaped plastic sheet 3. The adjustable bead 9 may, as described above in preferred embodiments, be tubular and / or comprise one or more reinforcement welds. Finally, each bag comprises at least one hole 12 adjacent to the open end 5 intended to stretch the adjustable cord 9 when the end user wishes to close the bag 1.

In an alternative embodiment the hem 8 can be placed internally on the U-shaped plastic sheet 3.

The difference between the bags 1 shown in Figures 4, 5 and 6 is in the positioning of the holes 12. The bag 1 shown in Figure 4 comprises a hole 12 positioned substantially midway between the sealed sides 6, 7. This embodiment is the least preferred of the embodiments shown. The bag 1 shown in Figure 5 also comprises a hole 12, but in this embodiment the hole is positioned adjacent to the sealed side 7 so that the hole 12 is intended to extend with a part, preferably half, of its cross-section over the bag 1 shown in Figure 5 and the other part, preferably the other half, in a bag adjacent to the bag 1 on the sealed side 7. Obviously, the hole 12 could also have been placed adjacent to the opposite sealed side 6. In the third embodiment shown in Figure 6, the hole 12 in the bag 1 is placed similar to that of Figure 5, only one hole 12 is provided on each sealed side 6, 7.

In an alternative, the hole 12 can be placed at a distance from the open end 5, such that a piece, for example, 0.5 to 1.5 cm, of the sealing strip 6 or 7 separates the hole 12 and the open end 5. This provides an improved guide of the adjustable cord 9 through the hole 12 when stretching the adjustable cord 9.

In all three cases, but particularly in the embodiments of Figures 5 and 6, the hole or holes 12 may replace the perforations that serve the same purpose as the hole (s) 12 allowing the area delimited by the perforations be torn off to provide access to the adjustable cord 9 to close the bag

1. Such perforations may be, for example, a row of straight or curved perforations.

As another possibility, although less preferred, also the adjustable cord 9 can be perforated along the same lines as the perforations replacing the holes 12, thus allowing the available

perforations during or after step 110 mentioned above (for example, simultaneously with the supply of the above-mentioned transverse seal with a weakened line) of the method according to the invention. In this way, the part of the adjustable cord 9 that extends within the area bounded by the row of perforations can also be torn off when said area bounded by the perforations. This

The last possibility can be used mainly in the embodiments shown in Figures 5 and 6.

It should be noted that the above description of the preferred embodiments is merely an example, and that one skilled in the art would know that numerous variations are possible without departing from the scope of the claims.

Claims (12)

1. Method for manufacturing adjustable drawstring bags comprising the stages of: providing a plastic material, extruding the plastic material to a longitudinal tubular sheet (2), cutting (104) longitudinally at least two strips (10, 11) of said tubular sheet (2), thus providing a U-shaped sheet (3) having two legs with an inner side (16), an outer side (17) and a free cut edge (18), carry (106) the at least two strips (10, 11) on one of said sides (16, 17 ) of said legs adjacent to the free cut edge (18), bend (108) the sheet adjacent to the free cut edges on said strips to form hems (8) and seal the hems to form tubular channels (19) in which they extend the strips, thus forming adjustable cords (9), seal (110) transversely the U-shaped sheet to provide a plurality of bags, and subject a portion of said tubular sheet (2) to a reinforcement treatment to provide reinforced strips (10 , 11) and thus form reinforced adjustable cords (9), in d where said reinforcement treatment comprises one or more of longitudinal sealing of said strips (10, 11) to form tubular adjustable cords (9) and to provide a portion of said tubular sheet (2) and / or the strips (10, 11) with one or more substantially longitudinal welds, transverse and / or inclined to provide adjustable cord reinforcement (9).

2.

 Method according to claim 1, characterized in that said sealing of said strips (10, 11) is performed by cutting said strips with a sealing blade (20, 21).

3.

Method according to claim 1, characterized in that said welds are provided by guiding a heated wheel through said part of said tubular sheet (2) and / or through all or a part of said strips (10, 11).

Four.

Method according to any one of the preceding claims, characterized in that it further comprises the step of drilling at least one hole (12) or at least one perforation in the material of said sheet to provide traction of said adjustable cord (9) when closing a bag.

5.

Method according to any of the preceding claims, characterized in that said plastic material is a polyolefin, such as a polypropylene or a polyethylene.

6.

Method according to any of the preceding claims, characterized in that a continuous line of adjustable drawstring bags is produced, each two bags being separated by a weakened line.

7.

Method according to any of the preceding claims, characterized in that it is performed as an online method.

8.

Method according to any of the preceding claims, characterized in that it further comprises the step of applying a coloring agent of a different color to that of the sheet (2 or 3) to said adjustable cord (9).

9.

An adjustable drawstring bag (1) comprising a U-shaped plastic sheet (3) that provides a closed bottom (4), an open end (5) and two sealed sides (6, 7), a hem (8 ) formed by folding and sealing the sheet at said open end on itself, and an adjustable cord (9) placed on said hem, said adjustable cord (9) being formed by at least two strips (10, 11) of the material of said U-shaped plastic sheet (3), where the sheet of said adjustable cord (9) has been subjected to a reinforcement treatment, characterized in that the result of the reinforcement treatment is one or more of the adjustable cord (9) is an adjustable tubular bead formed by longitudinally sealing said strips (10, 11) and that the adjustable bead (9) comprises one or more substantially longitudinal, transverse and / or inclined welds that extend over all or a portion of the adjustable bead (9 ).

10.

Bag according to claim 9, characterized in that it further comprises at least one hole (12) or at least one perforation in the material of said sheet, said hole or said perforation being adapted to stretch said adjustable cord (9) when closing a bag (one).

eleven.

Bag according to any of claims 9 to 10, characterized in that the tubular plastic sheet (2) is a polyolefin, such as a polypropylene or a polyethylene.

12.

Bag according to any of claims 9 to 11, characterized in that said adjustable cord (9) comprises a coloring agent of a different color from that of the sheet (3).