Patent Application
20240239556
The invention concerns the continuous manufacture of envelope-type flexible bags from a sheet of flexible material, particularly paper. It also concerns the addition of reinforcement layers providing mechanical and/or thermal characteristics in particular.
Industrial processes for manufacturing bags made of flexible materials such as paper or synthetic material have been known for a long time. For example, document FR 1 270 400 describes a machine and a process in which a strip is unreeled and formed into a tube. The tube is flattened in such a way that it comprises a first and a second wall, then the tube is cut into sections in such a way that at each end of the section there is a tab which prolongs the first or second wall. In a folding step, the tab is folded and bonded while being turned down on to the other wall than the one it extends from. It is thus possible to manufacture bags at a high rate with a large variety of materials and formats.
Document FR 786 579 shows several examples of this technique. In particular, in
In a variant, the tube is formed with bellows linking the first and second walls. Document WO 2016 097310 A1 shows an example of such bags. This document also shows a machine that is used to form an envelope from the tube using two stations each of which comprises a pair of contra-rotary cylinders whose work makes it possible to make the separation into sections and tear off a waste piece to reveal a tab at the front of the section on the same wall as the rear tab. Thus, after folding the tabs, they are applied to the same wall.
Such bags can be used as mail envelopes. In this case, the rear tab has an adhesive coat, for example protected by means of a protection such as a sheet of siliconized paper. This sheet can be removed, revealing the adhesive coat. The rear tab serves as a closure flap which can be folded to bring the adhesive coat against the wall opposite the one that the rear tab extends from, in such a way that the adhesive coat sticks to the wall, sealing the envelope. Thus, the wall that the tabs extend from has a smooth face when the tabs are stuck to the opposite face to close the envelope. When the envelope is received by its addressee, the latter tears the end of the envelope, for example at the level of the flap, to access the latter's content.
When manufacturing the bags, the removal of the waste piece is a limitation: on the one hand, it can be seen this is a limiting factor for the speed of bag manufacturing, and on the other hand the large amount of waste pieces is always a constraint that must be managed. Furthermore, the adjustment of such a machine requires a high level of technical expertise. A great deal of time is required to make the adjustment when changing the format of the bags, particularly in the case of a change of width, because the means of perforation will have to be changed.
The above-mentioned document FR 1 270 400 also describes a manufacturing process that can be used to make envelopes. A continuous sheet of paper is unreeled and then cuts are made on the edges in such a way as to create symmetrical bonding seams with respect to a longitudinal middle of the sheet and extending along an area of the sheet called the first flap. The seams are folded longitudinally on the sheet and coated with adhesive on the upper face, opposite the first flap. The sheet is cut into sections, for example by a clean cut and folded along a transversal crease to delimit the second flap which is folded over the first flap. The second flap is thus bonded to the seams and the container is delimited between the first flap and the second flap. The cut is made in such a way that a tab remains prolonging the first flap opposite the transversal crease.
The fact of making a clean cut instead of tearing gives a bag with a quality that is perceived as being better, the edge being sharper. However, this process also generates waste when making the lateral seams.
Document EP-3564146-A1 shows a bag manufacturing process that is quite similar to that in FR 1 270 400, but differs in that no cut is made in the edge. The flaps folded one on the other are bonded together along the edges. The process therefore does not generate any waste, but the useful width of the bag is reduced by the width of the areas bonded to each other. Furthermore, this type of bonding is more fragile because the constraints for separating one flap from the other are concentrated on the edge of the adhesive area.
Furthermore, there are needs for envelopes comprising reinforcements, either to make them stronger and better protect the content, or to insulate the content thermically or against impacts.
The invention aims to provide a process and a machine for manufacturing at high speed such envelope-type bags, with or without bellows, that does not generate any waste, makes it possible to strengthen the bag and is easy to adjust. The invention also aims to propose a bag produced in this way.
With these goals in view, the object of the invention is a process for manufacturing flexible bags, whereby:
This process makes it possible to produce envelope-type bags without producing waste, so without limitation on the production rate caused by having to manage the removal of such waste. The process uses the principle described in document FR 1 270 400 but without having to cut the edges. Indeed, the edges are folded over their whole length to form the hems and the latter are folded one onto the other after application of adhesive to assemble the two folded flaps one on the other. Cutting can be achieved by a clean-cutting means, that is to say by shearing, which gives a good perceived cutting quality. Cutting could also be achieved with a toothed knife cooperating with a groove to obtain the separation without any prior perforation lines. Cutting could also be obtained by tearing, that is to say by traction on a portion that has perforations initiating a cutting line. The cutting system is the same whatever the width of the bag to be made. It is therefore easy to change the width unlike for the manufacture of pouch-type bags by tearing off a waste piece which requires the installation of a special tool to make the perforations specific to the width. The flexible material could, for example, be paper with varying grammages, for example between 40 and 150 g/m2, synthetic material, textile or a combination of these materials.
As per an improvement,
We have thus produced a bag whose interior wall includes one or more reinforcement panels. The visual appearance of the exterior of the bag remains more or less the same, the reinforcement panels being hidden inside the bag. Each reinforcement panel can be formed by superposing multiple layers. The materials can be varied such as embossed paper to provide a layer of mechanical and thermal protection, a sheet of synthetic foam or including bubbles, or a reflective sheet.
As per an accomplishment mode, the length of the flaps is not the same in the longitudinal direction, in such a way that the second flap comprises a tab that is not covered by the first flap after folding, the tab not being covered by the reinforcement panel. The process makes it possible to manufacture envelope bags with the tab that is used to close the bag by folding over the first flap. As required for envelopes, the second flap remains free.
As per an improvement, a second strip of flexible material is unreeled, a second application of adhesive is made, and the second strip and the first strip are brought together on the internal face of the first strip, so they adhere to each other thanks to the second application of adhesive. This additional strip is used to provide specific properties for the interior of the bag, for example by providing a smooth surface inside the bag in the case where an embossed reinforcement is used or with a rough or adhesive surface. Preferably, it extends over the same length as the first strip.
In a special way, the system with at least one reinforcement panel is taken between the first and the second strip. Thus, the second strip is used to enclose the reinforcement panels.
As per one characteristic, the widths of the first and of the second strips are different in such a way that the hems extend from just one of said strips. This makes it possible to have a strip that serves as a mechanical reinforcement for the other strip, but without hindering the folding of the hems when they are formed.
As per an alternative characteristic, the width of the second strip is identical to that of the first strip. In this case the hems are formed by two layers, which reinforces them mechanically.
As per an accomplishment mode, a cheek is also formed on each edge of the first strip, the cheek being folded against the internal face and extending between the hem and a central part of the strip, in such a way that a stack is formed with, in this order, the central part, the cheek and the hem, the cheeks forming a bellows linking the first and second flap after the bonding of the hems, the system with at least one reinforcement panel not extending over the cheeks when the bag has cheeks. Considering the section of an edge of a flap, the central part, the cheek and the hem form a sort of Z which is flattened during manufacturing but can be deployed when using the bag.
As per an accomplishment mode, the system with at least one reinforcement panel comprises just one panel which extends over the first and the second flap. We enable a reinforcement of the flaps, including at the level of the folding crease.
As per another accomplishment mode, to form the system with at least one reinforcement panel, two reinforcement panels are successively cut out and placed, one on the first flap and the other on the second flap leaving an interval between them at the level of the transversal crease. Although this solution is more demanding, it makes it possible to use highly rigid reinforcement panels, while making it possible to easily make the folding crease.
As per an improvement, an area of closing adhesive is applied and a protection strip is placed on the area of closing adhesive so that they can be seen on the tab when the first flap is visible. This protection strip can be removed by the user before folding the tab onto the first flap and thus bond the tab to close the bag. This area of adhesive and this protection strip can be applied together or successively at different stages of the process. They can be applied, for example, directly after the unreeling of the first strip on the internal face, directly after the unreeling of the second strip where applicable, after cutting or even after the formation of the folding crease.
As per an improvement, the hem is also stuck to the face opposite the seam face solely along either the first flap or the second flap. Thus, considering one of the edges of the manufactured bag, the two hems are superposed and stuck to each other and, in addition, one of them only is stuck to the cheek where applicable, or to the internal face of the flap. It can be noted that this disposition makes it possible to stress the bonding essentially by sliding one hem over the other, whereas without bonding, the constraint is concentrated on the edge of the bonding and tears the bonding more easily.
As per an improvement, separate reinforcement strips are applied on the cheeks. This makes it possible to keep the flexibility of the join between the cheeks and the central part of the flaps while having a reinforcement of the cheeks. This also makes it possible to modulate the stiffness of the reinforcement panels between the central part and the cheeks.
Another object of the invention is a bag made of a flexible material comprising a first and a second flap extending from the same sheet folded along a transversal folding crease towards an internal face and brought together along the edges of the flaps perpendicular to the folding crease, characterised by the fact it comprises a hem formed on each edge, the hem of the first flap being stuck to the hem of the second flap on seam faces. The process such as described previously makes it possible to obtain such bags.
As per an improvement to the bag, the hem is linked to a central part of the flap by means of a cheek folded onto the central part, in such a way that a bellows is formed by two cheeks linked by the hems stuck to each other.
As per an improvement, a system with at least one reinforcement panel extends against the internal face of the flaps.
As per an improvement, a second strip of flexible material is bonded to the internal face of the first strip of flexible material and, in the case of the bag with a system with at least one reinforcement panel, the second strip of flexible material covers the system with at least one reinforcement panel. The second strip makes it possible to reinforce the bag, and give it specific properties that the first strip and the reinforcement panels do not have, for example for liquid-tightness.
As per an improvement, the system with at least one panel comprises several superposed reinforcement panels, the reinforcement panels having decreasing widths, each panel being bonded to either the first or the second strip by the surface not covered by the adjacent panel. Thus, it is not necessary to ensure bonding of the panels superposed over each other. A link to each panel is made with one of the strips, which ensures the positioning of the panels between the strips.
As per an improvement, the first flap is shorter than the second flap and leaves a tab extending from the second flap not covered by the first flap. There is therefore a tab making it possible, in particular, to close the bag by folding the tab onto the first flap, leaving the second flap with a smooth appearance.
The object of the invention is also a machine for manufacturing flexible bags comprising:
The upstream and downstream directions are defined with respect to the unreeling direction of the first strip. Such a machine is able to produce bags continuously such as described previously at a high rate, for example at rate of several hundreds of bags per minute. The hemmer could for example be a guide that causes the edge to fold over during the unreeling of the strip followed by a pair of rollers that grip the edge to mark the crease. The folding means are known, for example in document FR 1 270 400.
As per an improvement, the machine also comprises:
The first strip and reinforcement layer are unreeled in parallel then brought together by the intake means, consisting for example of a pair of contra-rotary rollers. The reinforcement layer is cut beforehand. The adhesive is applied either to the internal face of the first strip, in the area intended to receive the reinforcement layer, or on the panel. If you want to use several reinforcement layers, they are unreeled individually then assembled by other intake means before being presented to the second cutting means. For example, several layers of paper can be passed together through the intake means which also serves as embosser, that is to say which comprises two complementarily textured cylinders, in order to make hollows and bulges on the layers. The embosser is followed by a separator to separate each of the reinforcement layers and offset them with respect to each other so that the bulges are facing the bulges. In this way the stack of layers is made thicker to ensure a cushioning function.
As per an improvement, the machine comprises:
As per an improvement, the machine also comprises a cheek formation station also configured to form a cheek on each edge of the first strip, the cheek being folded against the internal face and extending between the hem and a central part of the strip, in such a way that a stack is made with, in this order, the central part, the cheek and the hem, the cheeks forming a bellows linking the first and second flaps after the bonding of the hems, the system with at least one reinforcement panel, when there is one, not extending over the cheeks. When a second strip is used, its width may be limited so as not to cover the cheeks or, on the contrary, also line the cheeks and possibly the hem.
The invention will be better understood and other features and advantages will appear on reading the following description, the description referring to the attached drawings among which:
A bag 1 envelope as per the invention's first accomplishment mode is shown in
In an accomplishment mode, the bag l′ differs from that of the first accomplishment mode in that the hem 15′ is linked to a central part 110 of the flap 11′, 12′ by means of a cheek 181 folded onto the central part 110, in such a way that a bellows 18 is formed by two cheeks 181 linked by the hems 15′ stuck together.
In a third accomplishment mode for making bag 1″, shown in
In a fourth accomplishment mode, shown in [
A machine 2 as per a first accomplishment mode of the invention enabling the manufacture of bags is shown schematically in [
Optionally, the machine comprises another hemmer 252 for making a hem on the edges of the second strip 1b in the case where the second strip is wider than the first strip and where the hems are only supported by the second strip 1b.
The first and second adhesive application means 211, 212 are, for example, flexographic rollers making it possible to apply adhesive according to a predetermined pattern. The adhesive is applied on the internal face 14 of the strip; that is to say on the face opposite the other strip after assembly.
The intake means 24 is made with a pair of contra-rotary rollers 241 driven by a motor, not shown. They apply a pressure to the strips 1a, 1b to obtain bonding between them and to the reinforcement panels 19a, 19b.
The feed means 22 also comprises intake means 221 for bringing together two reinforcement strips, then the second cutting means 220 for cutting the strips assembled into panels 19a, 19b, as detailed below.
The transport means 26 should preferably be means functioning by suction so as not apply any forces through the thickness of the assembly.
The application means 27 shall, for example, be nozzles injecting adhesive intermittently.
The first cutting means 28 and the folding means 29 are conventional and are not described here. The various parts are driven in rotation either by the same motor and synchronous mechanical transmissions such as cog belts or gears, or by several individual electronically synchronised motors, or a combination of the two solutions.
A machine 2′ conform to a second accomplishment mode, shown in [
In the second accomplishment mode, the width of the strip is subdivided into a central part 110, a cheek 181 and a hem area 15. By passing through the hemmer's application means, not shown, adhesive is applied at intervals on the edge of the hem area 15 over the length represented by the dashed lines 153 corresponding to the first flap 11, on the external face, opposite the internal face 14. The hem 15 is formed when passing through the hemmer 251 by folding over onto the external face and is stuck onto the length extending from the future cutting 111 of the section to the future folding crease 13, along what will be the first flap 11. Downstream of the intake means 24, the first strip 1a passes through the cheek formation station 181 in which the cheeks 181 are folded against the internal face 14 of the first strip 1a. The hem 15 becomes visible again above the first strip 1a, when looking at the internal face 14. After folding the cheek 181 against the internal face 14, the latter extends between the hem 15 and a central part 110 of the strip, in such a way that a stack is formed with, in the following order, the central part 110, the cheek 181 and the hem 15.
In both accomplishment modes, the visible face of the hems 15, also called seam face 150, is coated with adhesive over the same lengths on both sides of the future folding crease 13, then the first strip 1a is cut by the first cutting means 28 into sections, at the level of the cutting line 111. The sections are transferred to the folding means 29 which forms the folding crease 13 and folds the first flap 11 onto the second flap 12. The hems 15 of the first flap 11 then adhere to the hems 15 of the second flap 12 and the bag 1 is formed, as shown in [
[
The invention is not limited to the accomplishment modes which are described as examples only. The protection strip 17 and the coat of adhesive that it protects are optional or could take various forms.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2105064 | May 2021 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/062444 | 5/9/2022 | WO |
