STACK OF FLEXIBLE BAGS, METHOD AND MACHINE FOR PRODUCING SAID STACK

Abstract

Bags are made, with which a stack is formed. To do this, a tube is formed with a strip of flexible material, a portion of tube is separated at the front of the tube forming a first flap at the rear of the portion of tube, the first flap prolonging the first wall of the portion beyond the end of the second wall adjacent to the first wall, a bag is formed with each portion of tube, and a stack of bags is formed, the first wall of the first of the bags being against the second wall of the adjacent second bag. An anti-adhesive coating is applied on to the first wall of the first bag and a coat of adhesive is applied on to the second wall of the second bag ensuring the temporary attachment with the anti-adhesive coating.

Claims

1. A stack of flexible bags, each bag including a first flexible wall prolonged by a first flap at the first end of the bag and a second flexible wall adjacent to the first wall from which protrudes the first flap, the stack being characterised by the fact it includes means of attachment between each bag, the means of attachment including an anti-adhesive coating on the first wall of a first bag and a coat of adhesive ensuring a temporary attachment to the anti-adhesive coating and which also adheres to the second wall of the bag adjacent to the first bag, the coat of adhesive being able to adhere to the first flap on the second wall after the bag has been detached from the stack.

2. The stack according to claim 1, in which the anti-adhesive coating is supported by a strip added on to the first wall.

3. The stack according to claim 1, in which the anti-adhesive coating extends over the whole surface of the first wall.

4. The stack according to claim 1, wherein the stack includes separators separating a pre-determined number of bags.

5. The stack according to claim 1, in which the coat of adhesive is made with a repositionable adhesive.

6. A bag manufacturing process for forming a stack whereby a tube is made with a strip of flexible material, a portion of tube is separated at the front of the tube forming a first flap at the rear of the portion of tube, the first flap prolonging the first wall of the portion beyond the end of the second wall adjacent to the first wall, a bag is formed with each portion of tube by closing the front of the portion of tube, and a stack of bags is formed, the first wall of the first of the bags being against the second wall of the adjacent second bag attached to the first bag by means of attachment, characterised by the fact that an anti-adhesive coating is applied to the first wall of the first bag and a coat of adhesive is applied to the second wall of the second bag ensuring a temporary attachment with the anti-adhesive coating and thus forming the means of attachment, the coat of adhesive being able to bond the first flap on to the second wall after the bag has been detached from the stack.

7. The process according to claim 6 whereby the bag is closed by bonding a second flap protruding from the second wall on to the first wall, the coat of adhesive is applied to the anti-adhesive coating before the formation of the stack, and the coat of adhesive is transferred on to the second wall of the adjacent bag when the stack is formed.

8. The process according to claim 7 whereby a strip comprising an attachment layer, a substrate, the anti-adhesive coating and the coat of adhesive, is applied to the first wall, the strip being applied on to the first wall on the attachment coating side.

9. The process according to claim 7 whereby a strip comprising an attachment layer, a substrate and the anti-adhesive coating, is applied to the first wall, and in the next step the coat of adhesive is applied on to the anti-adhesive coating.

10. The process according to claim 6 whereby the bag is closed by bonding a second flap extending from the first wall on to the second wall, the coat of adhesive is applied on to the second wall and the anti-adhesive coating is applied on to the first wall, the coat of adhesive and the anti-adhesive coating being joined when the stack is formed.

11. The process according to claims 6 whereby the coat of adhesive is applied downstream of the closing of the bottom of the bag.

12. A machine for manufacturing flexible bags including a tube-forming device for forming a tube from a strip of flexible material , a separation device for separating a portion of tube at the front of the tube while forming a first flap to the rear of the portion of tube, the first flap prolonging the first wall of the portion beyond the end of the second wall adjacent to the first wall, a bag-bottom forming device for forming a bag with each portion of tube by closing the front of the portion of tube, and a stacking device for forming a stack of bags, the first wall of the first of the bags being against the second wall of the adjacent second bag, the machine being characterised by the fact it includes a first means of application for applying an anti-adhesive coating on to the first wall of the first bag, and a second means of application for applying a coat of adhesive on to the second wall of the second bag in such a way that the coat of adhesive is facing the anti-adhesive coating when the bags are stacked.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0030] Other advantages may well become apparent to an expert in the field on reading the examples below, illustrated by the appended figures, given as an illustration, amongst which:

[0031] FIG. 1 is a perspective view of a stack of bags conforming to a first accomplishment method using the invention;

[0032] FIG. 2 is a view similar to FIG. 1 of a stack of bags conforming to a second accomplishment method;

[0033] FIG. 3 is a view of a bag taken from the stack in FIG. 1, seen from the first face side;

[0034] FIG. 4 is a view of the bag in FIG. 3, seen from the second face side;

[0035] FIG. 5 is a schematic view of a machine for manufacturing a stack of bags conforming to the invention's first accomplishment method;

[0036] FIG. 6 is a partial section view of the stack in FIG. 1;

[0037] FIG. 7 is a view similar to FIG. 5 of a machine for manufacturing a stack of bags conforming to the invention's second accomplishment method.

DETAILED DESCRIPTION

[0038] A stack P of 10 flexible bags as per a first accomplishment method of the invention, is shown in FIG. 1. As shown in FIGS. 3 and 4, each bag 10 in stack P comprises a first flexible wall 11 prolonged by a first flap 13 at the first end 101 of the bag 10 and a second flexible wall 12 adjacent to the first wall 11 and from which protrudes the first flap 13. Bag 10 also comprises a second flap 14 extending from the second wall 12 folded and bonded on to the first wall 11 to close the bag 10 at the second end 102, opposite the first end 101, as shown in FIG. 3.

[0039] Stack P comprises means of attachment 9 between each bag 10. These attachment means 9 comprise an anti-adhesive coating 91 on the first wall 11 of the first bag 10, such as shown in FIG. 3, and a coat of adhesive 92 ensuring a temporary attachment with the anti-adhesive coating 91 and which also adheres to the second wall 12 of the bag 10 adjacent to the first bag 10, as shown in FIG. 4. The coat of adhesive 92 is able to bond to the first flap 13 on the second wall 12 after the bag 10 has been detached from stack P in order to close the first end 101 of bag 10.

[0040] The anti-adhesive coating 91 is, for example, supported by a strip added to the first wall 11, as shown in FIG. 6.

[0041] In a second accomplishment method of the invention, the stack P includes separators S separating a predetermined number of bags 10, as shown in FIG. 2. Each separator is attached by bonding on to one of the bags next to it. In this example, the bags 10 are envelope bags, that is to say the first 13 and second flaps 14 extend from the first wall, with only the second wall 12 being visible in FIG. 2.

[0042] The coat of adhesive 92 can be made with a repositionable adhesive or a permanent adhesive.

[0043] A machine for making stacks P of bags 10, such as shown in FIG. 5, includes in a manner known per se a station 4 for forming a tube 1 from a strip of flexible material la such as raw or pre-printed paper, an aluminium or plastic film or equivalent, or a combination of these materials. The strip of material la is unreeled from a reel on to a spool, not shown. It can be printed beforehand or at the output from the spool. The tube 1 is formed with or without bellows, but this characteristic does not have any impact on the invention. The machine then successively includes, in the tube 1 conveyance direction shown by arrow Fl, a pair of gripping rollers 3, a pair of tear-off rollers 6, a bag-bottom forming station 7 and then a stacking station 8 for forming the stack P of bags 10.

[0044] In order to specifically implement a process as per the invention, the machine also includes a first means of application 2 for applying the anti-adhesive coating 91 and a second means of application 5. The first means of application 2 may, for example, be provided to apply a strip 93 of self-adhesive silicon-coated paper, that is to say including an attachment coat 930 which is brought into contact with the tube 1 to be applied to it. In an example not shown, some adhesive is first of all applied to the tube, then the silicon-coated strip 93 is applied to the adhesive-coated area so it can adhere to it, the anti-adhesive face 91 remaining visible. Document GB390455 shows an example of a process for applying a paper reinforcement to a tube that can be used here for applying the anti-adhesive strip.

[0045] For example, the strip 93 includes the attachment coating 930, a substrate 931 and the anti-adhesive coating 91, the strip 93 being applied to the first wall 11 on the same side as the attachment coating 930.

[0046] The second means of application 5 is provided to apply a coat of adhesive 92 to the silicon-coated strip, that is to say to the anti-adhesive coating 91.

[0047] The functioning of the machine has now been broadly outlined, the detail of manufacturing a bag 10 already being known. The strip of flexible material la, including transversal lines of perforations at regular intervals, is unreeled then formed into a tube 1. The tube 1 receives the anti-adhesive coating 91 by the first means of application 2 on a first wall 11 of the tube and is then separated into sections lb at the front of the tube 1 by the combined action of the pairs of gripping rollers 3 and tear-off rollers 6, in a manner known per se. The separation is made along the lines of perforations that have been made in such a way that the first flexible wall 11 of the tube 1, in the upper part, is prolonged by a first flap 13 at the first end 101 of the bag 10 towards the back of the section, and a second flap 14 prolongs the second wall 12, in the lower part of the tube at the second end 102 towards the front of the section. A coat of adhesive 92 is applied to the anti-adhesive coating 91 by the second means of application 5. In a manner known per se, the second flap 14 is folded on to the first wall 11 and bonded to close the bag 10 by the bag-bottom forming device 7. Finally, the bags 10 arrive at the stacking station 8 where they are stopped in the upright position, the first wall 11 of bag 10 that arrives placing itself along the second wall 12 of the preceding bag 10. When the bags 10 are thus side by side, the coat of adhesive 92 carried by the anti-adhesive coating 91 comes into contact with the second wall 12 of the preceding bag 10 and adheres to it. As per the invention, the stack P is thus formed.

[0048] In a second accomplishment method of the invention, the bags 10 are of the envelope type, also called pouch bags, that is to say that both the flaps prolong the first wall, as shown in FIG. 2. In the manufacturing process known for this type of bag 10, the first wall is in the lower position, and the second wall 12 in the upper position. The machine, as shown in FIG. 7, is modified by the insertion of an additional pair of rollers 6 between the pairs of gripping rollers 3 and of tear-off rollers 6, and an additional tear-off step removes the waste at the first end 101 of the section of tube lb in order to form the first flap 13 prolonging the first wall in the lower position.

[0049] In this configuration, the first means of application 2 acts on the first wall, in the lower position therefore, to apply the anti-adhesive coating 91, whereas the second means of application 5 still acts on the upper part, to apply the coat of adhesive 92 on the second wall 12. When the bag 10 arrives at the packing station, the preceding bag 10 presents its first wall 11, with the anti-adhesive coating 91 applied, which assembles with the coat of adhesive 92 on the second wall 12 of the bag 10 which arrives to form the means of attachment 9. The separators S are deposited intermittently on the bag downstream of the bag-bottom forming device 7 by a third means of application 50.

[0050] The invention is not limited to the accomplishment modes that have been described to serve as examples. The second means of application could be integrated in the bag-bottom forming device 7 in order to apply the coat of adhesive 92 at the latest possible time in the progression of bag 10. Likewise, the first means of application 2 could be placed after the tear-off rollers 6 or also integrated in the bag-bottom forming device 7. In this case, the strip that is applied to the first wall 11 may include the attachment coating 930, the substrate 931, the anti-adhesive coating 91 and the coat of adhesive 92, the strip being applied to the first wall 11 on the attachment coating side. In order to make it possible to handle the strip, the latter is protected by a protection sheet that is removed after application of the strip on to the tube section. The bags presented are flat, but they could just as well have side bellows, formed when the tube is formed.