Method for producing a tube skirt decorated with an aesthetic lateral weld

Abstract

A method for producing a tube skirt for a flexible tube, said tube skirt being manufactured from a flat strip 1 comprising a decorative film 15 superimposed on a primary film 16, said primary film 16 comprising a sealable inner layer 14 at the lower surface 20 of the strip 1 as well as two stabilizing layers 11, 13, said decorative film 15 comprising a sealable outer layer 7 at the upper surface 19 of the strip 1, and a decorative layer 8, 9. This method comprises the following steps: winding the flat strip 1 into the form of a sleeve to shape the tube skirt; superimposing a first side border 2 of the strip 1 on a second side border 2 of the strip 1 to form an overlapping area 3, the sealable inner layer 14 of the primary film 16 of the first side border 2 overlapping the sealable outer layer 7 of the decorative film 15 of the second side border 2; applying a heating temperature T2 to the inside of the tube skirt at the inner face 22 of the overlapping area 3 to produce the side weld of the tube skirt; simultaneously with the application of the heating temperature T2, applying compression between the outer 21 and inner 22 faces of the overlapping area 3 so as to finalize the side weld of the tube skirt.

Claims

1. A method for producing a tube skirt for a flexible tube, said tube skirt being manufactured from a flat strip comprising a decorative film superimposed on a primary film, said primary film comprising a sealable inner layer at the lower surface of the strip as well as two stabilizing layers which import rigidity to a seam area and act as a reinforcement, said decorative film comprising a sealable outer layer at the upper surface of the strip, and a decorative layer, said method comprising: winding the flat strip into a form of a sleeve to shape the tube skirt; superimposing a first side border of the strip on a second side border 2 of the strip to form an overlapping area, the sealable inner layer of the primary film of the first side border overlapping the sealable outer layer 7 of the decorative film 15 of the second side border 2; applying a heating temperature to the inside of the tube skirt at the inner face of the overlapping area to produce the side weld of the tube skirt; simultaneously with the application of the heating temperature, applying compression between the outer and inner faces of the overlapping area so as to finalize the side weld of the tube skirt, wherein a different heating temperature is applied, simultaneously with the heating temperature applied to the inside of the tube skirt, on the outer face of the overlapping area, the different heating temperature being lower than the heating temperature applied to the inside of the tube skirt.

2. The method according to claim 1, wherein the heating temperature is higher than a melting temperature of the sealable inner layer of the primary film and the sealable outer layer of the decorative film, and lower than a melting temperature of the decorative layer of the decorative film and the two stabilizing layers of the primary film.

3. The method according to claim 1, wherein the different heating temperature is lower than a melting temperature of material making up the sealable outer layer.

4. The method according to claim 3, wherein the material making up the sealable outer layer comprises polyethylene, and wherein the melting temperature of the material is above 120 C., and the different heating temperature is lower than 120 C.

5. The method according to claim 4, wherein the different heating temperature is less than 100 C.

6. The method according to claim 1, further comprising preheating the overlapping area before superimposing the side borders.

7. The method according to claim 6, wherein the preheating comprises blowing hot air into an interstitial space separating the first side border from the second side border 2 before the superimposition of the first side border on the second side border.

8. The method according to claim 1, further comprising cooling the overlapping area after the application of the compression.

9. The method according to claim 8, wherein the cooling comprises cooling the inner face of the overlapping area.

10. The method according to claim 1, wherein the overlapping area has a width between 1.5 and 2.5 mm.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The invention will be better understood, and other aims, details, features and advantages thereof will appear more clearly, during the following explanatory detailed description done of at least one embodiment of the invention, provided solely as an illustrative and non-limiting example, in reference to the appended diagrammatic drawings.

(2) In these drawings:

(3) FIG. 1 is a top view of a strip according to the invention;

(4) FIG. 2 is a cross-sectional view of the strip of FIG. 1;

(5) FIG. 3 is a cross-sectional view of a tube skirt formed from the strip of FIG. 1;

(6) FIG. 4 lists the different layers at the overlapping area of the tube skirt of FIG. 3;

(7) FIG. 5 shows the overlapping area of the tube skirt of FIG. 3 before producing the side weld, according to a first embodiment;

(8) FIG. 6 shows the overlapping area of the tube skirt of FIG. 3 before producing the side weld, according to a second embodiment;

(9) FIG. 7 shows the overlapping area of the tube skirt of FIG. 3 after producing the side weld, for the first and second embodiments;

(10) FIG. 8 is a perspective view of part of the tooling needed to produce the side weld of the tube skirt of FIG. 3;

(11) FIG. 9 is an exploded view of the cooling device belonging to the tooling of FIG. 8;

(12) FIG. 10 shows the details of the small cooling strip of the cooling device of FIG. 9;

(13) FIG. 11 is a detailed view of the heating device belonging to the tooling of FIG. 8.

DETAILED DESCRIPTION

(14) The terms outer and outside are used to indicate that a layer is oriented toward the outside of the tube skirt thus formed. Likewise, the terms inner and inside are used to indicate that a layer is oriented toward the inside of the tube skirt thus formed.

(15) In reference to FIGS. 1 and 2, a segment of a flat strip 1 according to the invention is shown, which will next be wound to form a tube skirt.

(16) This strip 1 includes a central area 4 bordered by first 2 and second 2 side borders.

(17) It is known to obtain such a strip 1 by using multilayer films obtained by extrusion or by rolling-gluing.

(18) The flat strip 1 according to the invention includes a series of layers.

(19) Concretely, it is made up of a decorative film 15 topping a primary film 16.

(20) In each embodiment, the decorative film 15 comprises a sealable outer layer 7 situated at the upper surface 19 of the strip 1, and a decorative layer 8, 9 made up of a PET base 9 situated below the sealable outer layer 7.

(21) The decorative layer 8, 9 is applied over the entire surface of the decorative film 15 and is situated below the sealable outer layer 7. In other words, there are no areas belonging to the decorative film 15 that are not covered by both the decorative layer 8, 9 and the sealable outer layer 7.

(22) This decorative layer 8, 9 may contain a metallic or holographic film 8, or the like, depending on the selected type of decoration. It makes up the background of the decoration of the tube that will subsequently be formed.

(23) Preferably, this film 8 is applied on the top of the PET base 9, so that it is oriented toward the upper surface 19 of the strip 1. In another possible configuration, this film 8 could be applied on the bottom of the PET base 9. The PET base consists of a high-density layer, which plays a reinforcing role during the formation of the tube skirt. This layer 9 is crosshatched in FIG. 2.

(24) The decorative layer 8, 9 of the decorative film 15 has a thickness comprised between 5 and 50 m, preferably between 10 and 30 m.

(25) In all cases, the sealable outer layer 7 is situated above the decorative layer 8, 9 and therefore protects the latter against impacts/scratches related to futures handling of the tube skirt thus formed. The sealable outer layer 7 is preferably transparent, such that the decoration can be clearly visible from outside the tube that will be formed.

(26) This sealable outer layer 7 is made from PE, and may also have multiple layers. Preferably, the sealable outer layer 7 is made up of three layers of PE. Preferably, the material chosen for the three layers will be MDPE, owing to its technical characteristics.

(27) In general, the sealable outer layer 7 of the decorative film 15 has a thickness comprised between 5 and 90 m, preferably between 5 and 80 m.

(28) Optionally, on top of the decorative layer 8, 9, the decorative film 15 can be printed directly on the sealable outer layer 7, in order to add decoration. Thus, an additional printed layer 6, as well as a protective layer 5 (varnish type), can extend over part of the outer surface of the decorative film 8, 9. More specifically, these two printed 6 and protective 5 layers extend over the central area 4 and the first side border 2 of the strip 1. In other words, the two printed 6 and protective 5 layers extend over the entire surface area of the strip 1, aside from the second side border 2 (see crosshatched area in FIG. 1). This is the side border 2 that will be covered by the first side border 2 during formation of the tube skirt. Since the ink and the varnish are not sealable, it is mandatory that none be placed on the second border 2 that will be overlapped to produce the side weld.

(29) The primary film 16 is a multilayer film that comprises a sealable inner layer 14 situated at the lower surface 20 of the strip 1, as well as two stabilizing layers 11, 13 distributed symmetrically in the primary film 16 relative to its median plane X and crosshatched in FIG. 2 to show their reinforcing role.

(30) The primary film 16 may comprise up to 22 layers.

(31) At least one layer consists of a barrier layer making it possible to seal against humidity and preserve aromas relative to the product that will be poured inside the tube thus formed by the wound strip 1.

(32) The other layers may be chosen from among polyethylenes, for example a low-density polyethylene (LDPE), a linear low-density polyethylene (LLDPE), a medium-density polyethylene (MDPE), a high-density polyethylene (HDPE), or a mixture of these polyethylenes, or ethylene vinyl acetate (EVA). Between these different layers, a bonding layer and/or an adhesive coating can be applied in order to improve the adherence between the layers.

(33) The primary film 16 has a thickness comprised between 100 and 500 m, preferably between 200 and 350 m.

(34) The primary film 16 can be a blown film, in order to have symmetry between its various layers.

(35) In this case, the double central layer 12 will preferably be made up of EVA, which has a good ability to stick to itself during flattening of the blown sheath. The two stabilizing layers 11, 13 are distributed symmetrically on either side of the median plane X of the film 16 made by the double layer of EVA 12. These stabilizing layers 11, 13 are made up of EVOH. EVOH has also proven to be a material capable of serving as a sealing barrier. Consequently, the two layers of EVOH 11, 13 perform the dual function of reinforcing and sealing within the primary film 16. Lastly, the sealable inner layer 14 also has its liner, situated symmetrically in the primary film 16, corresponding to a sealable outer layer 10 of the primary film 16, and which is therefore in contact with the lower layer of the decorative film 15. The two sealable layers 10, 14 of the primary film 16 are made up of MDPE, in order to correspond to the sealable outer layer 7 of the decorative film 15.

(36) Below are detailed examples of structures forming the strip 1 according to the invention.

EXAMPLE 1

(37) TABLE-US-00001 Density thickness Layer Material (g/cm3) (m) Correspondence with FIGS. 1 and 2 1 MDPE 0.934 15 Sealable outer layer 7 Decorative 2 MDPE 0.934 22 film 15 3 MDPE 0.934 13 4 Adhesive 4 Adhesive layer coating 5 PET + 1.417 12 Decorative layer 8, 9 metallic film (toward the bottom) 6 Adhesive 4 Adhesive layer coating 7 MDPE 0.934 109 Sealable outer layer 10 Primary 8 Resin 0.91 7 Adhesive layer film 16 9 EVOH 1.17 10 Stabilizing layer 11 10 Resin 0.92 7 Adhesive layer 11 EVA 0.941 17 2 Central layer 12 12 Resin 0.92 7 Adhesive layer 13 EVOH 1.17 10 Stabilizing layer 13 14 Resin 0.91 7 Adhesive layer 15 MDPE 0.934 109 Sealable inner layer 14

EXAMPLE 2

(38) TABLE-US-00002 Thickness Correspondence with Layer Material (m) FIGS. 1 and 2 1 MDPE 15 Sealable outer layer 7 Decorative 2 MDPE 22 film 15 3 MDPE 13 4 Adhesive Adhesive layer coating 5 metallic film 12 Decorative layer 8, 9 (toward the top) + PET 6 Adhesive coating Adhesive layer 7 MDPE 72 Sealable outer layer 10 Primary 8 Resin 7 Adhesive layer film 16 9 EVOH 7 Stabilizing layer 11 10 Resin 7 Adhesive layer 11 MDPE 40 12 EVA 17.3 2 Central layer 12 13 MDPE 40 14 Resin 7 Adhesive layer 15 EVOH 7 Stabilizing layer 13 16 Resin 7 Adhesive layer 17 MDPE 72 Sealable inner layer 14

(39) During the formation of the tube skirt, by winding the strip 1, the first side border 2 overlaps the second side border 2, as illustrated in FIG. 3.

(40) FIG. 4 shows the series of layers in the overlapping area 3.

(41) For better clarity, the layers situated at the second side border 2 have a numbering corresponding to the layers situated at the first side border 2, since they are the same layers, but are numbered with an additional prime to differentiate them.

(42) In order, from the outside of the tube skirt toward the inside of the tube skirt, the layers are as follows: 5: the protective layer of the first side border 6: the printed layer of the first side border 7: the sealable outer layer of the decorative film of the first side border 8: the metallic coating of the decorative film of the first side border 9: the PET layer bearing the metallic coating of the decorative film of the first side border 10: the sealable outer layer of the primary film of the first side border 11: the stabilizing EVOH layer of the primary film of the first side border 12: the central layer of the primary film of the first side border 13: the stabilizing EVOH layer of the primary film of the first side border 14: the sealable inner layer of the primary film of the first side border 7: the sealable outer layer of the decorative film of the second side border 8: the metallic coating of the decorative film of the second side border 9: the PET layer bearing the metallic coating of the decorative film of the second side border 10: the sealable outer layer of the primary film of the second side border 11: the stabilizing EVOH layer of the primary film of the second side border 12: the central layer of the primary film of the second side border 13: the stabilizing EVOH layer of the primary film of the second side border 14: the sealable inner layer of the primary film of the second side border

(43) The adhesive intermediate layers are not shown for greater clarity.

(44) It should be noted that the sealable inner layer 14 of the primary film 16 of the first side border 2 is indeed situated directly on the sealable outer layer 7 of the decorative film 15 of the second side border 2. These two sealable MDPE layers 14, 7 will melt and fuse during the side welding, thereby allowing the two side borders 2, 2 to be welded to one another.

(45) FIG. 5 precisely shows the overlapping done to form the tube skirt, before producing the side weld, and according to a first embodiment. In this case, a heating temperature T2 comprised between 125 C. and 180 C. is applied on the inner surface 22 of the tube skirt, more specifically on the sealable inner layer 14 of the primary film 16 of the second MDPE side border 2.

(46) At the same time, a heating temperature T1, much lower than the heating temperature T2 and below 120 C., is applied on the outer surface 21 of the tube skirt, more specifically on the sealable outer layer 7 of the decorative film 15 of the first MDPE side border 2.

(47) At the same time as the heating, the overlapping area 3 is compressed at both its outer 21 and inner 22 faces in order to help the melting layers mix and adhere to one another so as to produce the side weld of the tube skirt.

(48) Concretely, the following layers will melt owing to the heating temperature T2:

(49) 14: the sealable inner layer of the primary film of the first side border

(50) 7: the sealable outer layer of the decorative film of the second side border

(51) 10: the sealable outer layer of the primary film of the second side border

(52) 12: the central layer of the primary film of the second side border

(53) 14: the sealable inner layer of the primary film of the second side border

(54) The intermediate bonding layers will also melt.

(55) The stabilizing layers 11, 11, 13, 13 and the decorative metallic PET layers 8, 9, 8, 9 will not melt and will not mix with the other layers, thereby making it possible to preserve order in the layers during welding and after welding, and to retain stability in the heated structure.

(56) The two stabilizing EVOH layers 11, 13 of the primary film 16 of the first side border 2 also make it possible to protect the decorative metallic PET layer 8, 9 from heating coming from the heating temperature T2, since the metallic PET layer is sensitive to heating and becomes fragile.

(57) This is particularly visible in FIG. 7, where the deformations of the different layers are shown after producing the side weld. It is clearly visible that the stabilizing layers 11, 11, 13, 13 and the decorative metallic PET layers 8, 9, 8, 9 are not mixed with the other layers and have simply been deformed under the action of the compression. The layers upstream from, downstream from, and between the stabilizing layers have been mixed and fused. The weld seam is indeed located inside the tube skirt.

(58) It should be noted that the metallic PET layer 8, 9 of the second side border 2 has also been protected against heating by two stabilizing EVOH layers 11, 13 of the second side border 2, in particular in the new junction area 17 between the two side borders 2, 2 on the surface area of the tube skirt.

(59) This junction area 17 is very narrow, the two borders 2, 2 being very close, and the discontinuity of the printed layer 6 on the tube skirt is thus minimal. The tube skirt thus formed is aesthetically pleasing, and has a robust weld.

(60) In a second embodiment, instead of applying a heating temperature T1 on the outer surface 21 of the tube skirt, it is possible to preheat the overlapping area 3 by blowing hot air 18 into the interstitial space separating the first side border 2 from the second side border 2 before they are superimposed, as illustrated in FIG. 6.

(61) The goal is to soften the layers beforehand that are intended to melt during the side welding, in particular the layers oriented toward the outside of the tube skirt, in order to obtain a weld with a uniform appearance from the outside of the tube skirt.

(62) The end result is similar to that of the first embodiment, and corresponds to that shown in FIG. 7.

(63) FIG. 8 shows tooling suitable for carrying out the manufacturing method as previously described.

(64) This tooling primarily involves a cylindrical mandrel 30 extending longitudinally along an axis Y, and able to be fastened on a frame (not shown). This mandrel 30 is made up of a first end segment 31, an inner heating segment 32, an inner cooling segment 33, and a second end segment 34.

(65) The flexible strip (not shown) is guided so as to wind around the mandrel 30, and such that a first side border of the strip overlaps a second side border of the strip, thus forming an overlapping area situated in the upper part of the mandrel 30. The part of the device allowing winding of the strip will not be described, since it has been known and widely used for many years.

(66) The overlapping area of the tube skirt thus formed first arrives at the inner heating segment 32 of the mandrel 30, more specifically shown in FIG. 11. This segment 32 comprises a slot 35 formed in the upper part of the mandrel 30, in which an insulating part 36 is housed able to accommodate a heating part 37 that will be in contact with the inner face of the overlapping area to produce the side weld.

(67) The slot 35 has a parallelepiped shape. The insulating part 36 is U-shaped with its angular outer walls marrying the shape of the slot 35 of the mandrel 30.

(68) The heating part 37 consists of a cylinder whereof the lower 38 and upper 39 parts comprise a flat respectively allowing it to be positioned correctly at the bottom of the insulating part 36 with planar contact, and to have an upper planar surface 39 with a width L1 that corresponds at least to that of the overlapping area. This heating part 37 thus positioned can heat the inner face of the overlapping area to the heating temperature T2, in order to produce the side weld. In parallel, a movable metal strip (not shown) presses on the outer face of the overlapping area in order to exert compression on the overlapping area and help the various melting layers mix and ensure that there is no setback at the overlapping area, i.e., that the outer surface of the tube skirt is linear over its entire circumference. This compression also makes it possible to reduce the ultimate thickness of the side weld.

(69) Optionally, an outside heating means (not shown) located across from the mandrel 30 can be provided on the device to heat the outer face of the overlapping area to the heating temperature T1. This heating means can be associated with the movable strip.

(70) When the side weld is produced, the tube skirt, in particular driven via the movable metal strip, arrives at the central part of the mandrel 30 where casters 40 are arranged having a traditional compression and shaping function of the tube skirt at the overlapping area.

(71) Then the tube skirt arrives at the cooling segment 33 of the mandrel 30, shown in more detail in FIG. 9. This segment 33 also includes a slot 41 formed at the upper surface of the mandrel 30. This slot 41 forms a hollow parallelepiped space.

(72) Within this slot 41, a small cooling strip 42, also parallelepiped, is housed. The dimensions of the small strip 42 and the slot 41 coincide in order to ensure optimal positioning in one another. The small strip 42 is therefore fixed within the mandrel 30.

(73) This small strip 42 comprises a flat upper wall 43 that is arranged and able to come directly into contact with the inner face of the overlapping area. The latter will therefore be cooled via this planar contact with the flat wall 43 of the small strip 42. The cooling temperature is therefore regulated from the temperature measured on the surface of the flat wall 43. This upper wall 43 has a width L2 at least as large as that of the overlapping area so as to cool the entire side seam well.

(74) Below this flat wall 43 is a channel 44 inside which a coolant circulates. In the present example, this channel 44 has a crenulated shape, as illustrated in FIG. 10. Indeed, a plurality of fins 45 extend perpendicular to the flat wall 43 of the small strip 42 toward the central axis Y of the mandrel 30. These fins 45 form two longitudinal rows 46, 47 developing along an axis parallel to the axis Y of the mandrel 30, and are arranged in staggered rows so as to form the crenulation. The coolant thus circulates between the fins 45, following the crenulated path 44, as illustrated by the arrows. This path 44 forces the fluid to cross, and thus spend more time within, the small strip 42 in order to favor heat exchanges.

(75) The fins 45 make it possible to increase the heat exchange surface between the overlapping area, still hot after the welding, on the one hand, and the cold coolant, on the other hand. By increasing the exchange surface in this way, the cooling performance is also increased. Thus, the length of the cooling segment 33 of the mandrel 30 according to the invention can be greatly reduced while obtaining optimal cooling results relative to a cooling device without fins 45, and/or having a rectilinear cooling channel 44. The mandrel 30 according to the invention therefore has the advantage of being compact.

(76) Preferably, the fins 45 consist of rectangular tongues. However, they could have other advantageous shapes.

(77) The same is true for the cooling channel 44, which may assume other advantageous forms.

(78) During the cooling step, the overlapping area preferably continues to be compressed via the movable strip.